Making Microbiology Even Smaller!
Young, Linda Mull; Motz, Vicki Abrams
2013-01-01
We outline protocols for producing slant-minis (SLINIs) and mini-deeps (MEEPs) and examples of their use in simple microbiology experiments suitable for high school students. The principal benefits of these protocols are decreased cost associated with significantly reduced media use; easier, less expensive disposal of waste; and increased safety…
Chernobyl birds have smaller brains.
Directory of Open Access Journals (Sweden)
Anders Pape Møller
2011-02-01
Full Text Available Animals living in areas contaminated by radioactive material from Chernobyl suffer from increased oxidative stress and low levels of antioxidants. Therefore, normal development of the nervous system is jeopardized as reflected by high frequencies of developmental errors, reduced brain size and impaired cognitive abilities in humans. Alternatively, associations between psychological effects and radiation have been attributed to post-traumatic stress in humans.Here we used an extensive sample of 550 birds belonging to 48 species to test the prediction that even in the absence of post-traumatic stress, there is a negative association between relative brain size and level of background radiation. We found a negative association between brain size as reflected by external head volume and level of background radiation, independent of structural body size and body mass. The observed reduction in brain size in relation to background radiation amounted to 5% across the range of almost a factor 5,000 in radiation level. Species differed significantly in reduction in brain size with increasing background radiation, and brain size was the only morphological character that showed a negative relationship with radiation. Brain size was significantly smaller in yearlings than in older individuals.Low dose radiation can have significant effects on normal brain development as reflected by brain size and therefore potentially cognitive ability. The fact that brain size was smaller in yearlings than in older individuals implies that there was significant directional selection on brain size with individuals with larger brains experiencing a viability advantage.
Ferragut, G.; Liu, T.; Klemperer, S. L.
2017-12-01
In recent years Virtual Deep Seismic Sounding (VDSS) emerged as a novel method to image the Moho, which uses the post-critical reflection P waves at the Moho generated by teleseismic S waves at the free surface near the receivers (SsPmp). However, observed SsPmp sometimes have significantly lower amplitude than predicted, raising doubts among the seismic community on the theoretical basis of the method. With over two decades of continuous digital broadband records and major subduction zones in the range of 30-50 degrees, the Yellowknife Array in northern Canada provides a rich opportunity for observation of post-critical SsPmp. We analyze S wave coda of events with epicenter distances of 30-50°, and pay special attention to earthquakes in a narrow azimuth range that encompasses the Kamchatka Peninsula. Among 21 events with strong direct S energy on the radial components, we observe significant variation of SsPmp energy. After associating the SsPmp energy with the virtual source location of each event, we observe a general trend of decreasing SsPmp energy from NE to SW. As the trend coincides with the transition from exposed basement of the Slave Craton to Paleozoic platform covered by Phanerozoic sediment, we interpret the decreasing SsPmp energy as a result of lower S velocity at the virtual sources, which reduces S-to-P reflection coefficients. We plan to include more events from the Aleutian Islands, the virtual sources of which are primarily located in the Paleozoic platform. This will allow us to further investigate the relationship between SsPmp amplitude and near-surface velocity.
Synchrotron radiation gives insight in smaller and smaller crystals
International Nuclear Information System (INIS)
Hintsches, E.
1983-01-01
Scientists from the ''Max-Planck-Institut fuer Festkoerperforschung'' in Stuttgart have extended the method of X-ray analysis to study the structure of very small crystals. For the first time a crystal with 6 μm linear dimension has been successfully analysed using the synchrotron radiation from the DESY electron synchrotron at Hamburg. Thus this important method of analysis has been demonstrated to be usefull for structural studies of crystals, which are smaller by a factor of 20 than hitherto. (orig.) [de
Collage of Saturn's smaller satellites
1981-01-01
This family portrait shows the smaller satellites of Saturn as viewed by Voyager 2 during its swing through the Saturnian system. The following chart corresponds to this composite photograph (distance from the planet increases from left to right) and lists names, standard numerical designations and approximate dimensions (radii where indicated) in kilometers: 1980S26Outer F-ringshepherd120 X 100 1980S1Leadingco-orbital220 X 160 1980S25TrailingTethys trojanradii: 25 1980S28Outer Ashepherdradii: 20 1980S27Inner F-ringco-orbital145 X 70 1980S3TrailingTethys trojan140 X 100 1980S13LeadingTethys trojanradii: 30 1980S6LeadingDione trojanradii: 30 These images have been scaled to show the satellites in true relative sizes. This set of small objects ranges in size from small asteroidal scales to nearly the size of Saturn's moon Mimas. They are probably fragments of somewhat larger bodies broken up during the bombardment period that followed accretion of the Saturnian system. Scientists believe they may be mostly icy bodies with a mixture of meteorite rock. They are somewhat less reflective than the larger satellites, suggesting that thermal evolution of the larger moons 'cleaned up' their icy surfaces. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.
75 FR 35881 - Smaller Learning Communities Program
2010-06-23
... Part II Department of Education Smaller Learning Communities Program; Notice #0;#0;Federal... EDUCATION Smaller Learning Communities Program Catalog of Federal Domestic Assistance (CFDA) Number: 84.215L. AGENCY: Office of Elementary and Secondary Education, Department of Education. ACTION: Notice of final...
Storm Sewage Dilution in Smaller Streams
DEFF Research Database (Denmark)
Larsen, Torben; Vestergaard, Kristian
1987-01-01
A numerical model has been used to show how dilution in smaller streams can be effected by unsteady hydraulic conditions caused by a storm sewage overflow.......A numerical model has been used to show how dilution in smaller streams can be effected by unsteady hydraulic conditions caused by a storm sewage overflow....
Accommodative Amplitude in School-Age Children
Directory of Open Access Journals (Sweden)
Ikaunieks Gatis
2017-10-01
Full Text Available In children, intensive near-work affects the accommodation system of the eye. Younger children, due to anatomical parameters, read at smaller distance than older children and we can expect that the accommodation system of younger can be affected more than that of older children. We wanted to test this hypothesis. Some authors showed that the norms of amplitude of accommodation (AA developed by Hofstetter (1950 not always could be applied for children. We also wanted to verify these results. A total of 106 (age 7-15 children participated in the study. Distance visual acuity was measured for all children and only data of children with good visual acuity 1.0 or more (dec. units were analysed (73 children. Accommodative amplitude was measured before and after lessons using subjective push-up technique (with RAF Near Point Ruler. The results showed that the amplitude of accommodation reduced significantly (p < 0.05 during the day and decrease of AA was similar in different age groups (about ~0.70 D. Additional measurements are needed to verify that the observed changes in AA were associated with fatigue effect. The results showed lower accommodation values compared to average values calculated according to the Hofstetter equation (p < 0.05.
Unit size limitations in smaller power systems
International Nuclear Information System (INIS)
McConnach, J.S.
1975-01-01
The developing nations have generally found it an economic necessity to accept the minimum commercial size limit of 600 MWe. Smaller reactor sizes tendered as 'one off' specials carry high specific cost penalties which considerably weaken the competitiveness of nuclear versus conventional thermal plants. The revised IAEA market survey for nuclear power in developing countries (1974 edition) which takes account of the recent heavy escalation in oil prices, indicates a reasonable market for smaller size reactors in the range 150 MWe to 400 MWe, but until this market is approached seriously by manufacturers, the commercial availability and economic viability of smaller size reactors remains uncertain. (orig.) [de
Amplitude Variations in Pulsating Red Giants. II. Some Systematics
Percy, J. R.; Laing, J.
2017-12-01
In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.
Smaller sized reactors can be economically attractive
International Nuclear Information System (INIS)
Carelli, M.D.; Petrovic, B.; Mycoff, C.W.; Trucco, P.; Ricotti, M.E.; Locatelli, G.
2007-01-01
Smaller size reactors are going to be an important component of the worldwide nuclear renaissance. However, a misguided interpretation of the economy of scale would label these reactors as not economically competitive with larger plants because of their allegedly higher capital cost (dollar/kWe). Economy of scale does apply only if the considered designs are similar, which is not the case here. This paper identifies and briefly discusses the various factors which, beside size (power produced), contribute to determining the capital cost of smaller reactors and provides a preliminary evaluation for a few of these factors. When they are accounted for, in a set of realistic and comparable configurations, the final capital costs of small and large plants are practically equivalent. The Iris reactor is used as the example of smaller reactors, but the analysis and conclusions are applicable to the whole spectrum of small nuclear plants. (authors)
Do parents leave a smaller carbon footprint?
DEFF Research Database (Denmark)
Nordström, Leif Jonas; Shogren, Jason F.; Thunström, Linda
Do parents leave a smaller carbon footprint? While becoming a parent is transformational as one focuses more on the future, the time constraints are more binding right now. Using a unique data set that allows us to compare CO2 emissions from Swedish two-adult households with and without children......, we find becoming a Swedish parent causes a person to leave a larger carbon ootprint—due to changes in transportation patterns and food consumption choices....
Diphoton generalized distribution amplitudes
International Nuclear Information System (INIS)
El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.
2008-01-01
We calculate the leading order diphoton generalized distribution amplitudes by calculating the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region at the Born order and in the leading logarithmic approximation. As in the case of the anomalous photon structure functions, the γγ generalized distribution amplitudes exhibit a characteristic lnQ 2 behavior and obey inhomogeneous QCD evolution equations.
Is the effect of tinnitus on auditory steady-state response amplitude mediated by attention?
Directory of Open Access Journals (Sweden)
Eugen eDiesch
2012-05-01
Full Text Available Objectives: The amplitude of the auditory steady-state response (ASSR is enhanced in tinnitus. As ASSR ampli¬tude is also enhanced by attention, the effect of tinnitus on ASSR amplitude could be interpreted as an effect of attention mediated by tinnitus. As attention effects on the N1 are signi¬fi¬cantly larger than those on the ASSR, if the effect of tinnitus on ASSR amplitude were due to attention, there should be similar amplitude enhancement effects in tinnitus for the N1 component of the auditory evoked response. Methods: MEG recordings of auditory evoked responses which were previously examined for the ASSR (Diesch et al. 2010 were analysed with respect to the N1m component. Like the ASSR previously, the N1m was analysed in the source domain (source space projection. Stimuli were amplitude-modulated tones with one of three carrier fre¬quen¬cies matching the tinnitus frequency or a surrogate frequency 1½ octaves above the audio¬metric edge frequency in con¬trols, the audiometric edge frequency, and a frequency below the audio¬metric edgeResults: In the earlier ASSR study (Diesch et al., 2010, the ASSR amplitude in tinnitus patients, but not in controls, was significantly larger in the (surrogate tinnitus condition than in the edge condition. In the present study, both tinnitus patients and healthy controls show an N1m-amplitude profile identical to the one of ASSR amplitudes in healthy controls. N1m amplitudes elicited by tonal frequencies located at the audiometric edge and at the (surrogate tinnitus frequency are smaller than N1m amplitudes elicited by sub-edge tones and do not differ among each other.Conclusions: There is no N1-amplitude enhancement effect in tinnitus. The enhancement effect of tinnitus on ASSR amplitude cannot be accounted for in terms of attention induced by tinnitus.
Kaon decay amplitudes using staggered fermions
International Nuclear Information System (INIS)
Sharpe, S.R.
1986-12-01
A status report is given of an attempt, using staggered fermions to calculate the real and imaginary parts of the amplitudes for K → ππ,. Semi-quantitative results are found for the imaginary parts, and these suggest that ε' might be smaller than previously expected in the standard model
Two Photon Distribution Amplitudes
International Nuclear Information System (INIS)
El Beiyad, M.; Pire, B.; Szymanowski, L.; Wallon, S.
2008-01-01
The factorization of the amplitude of the process γ*γ→γγ in the low energy and high photon virtuality region is demonstrated at the Born order and in the leading logarithmic approximation. The leading order two photon (generalized) distribution amplitudes exhibit a characteristic ln Q 2 behaviour and obey new inhomogeneous evolution equations
Amplitudes, acquisition and imaging
Energy Technology Data Exchange (ETDEWEB)
Bloor, Robert
1998-12-31
Accurate seismic amplitude information is important for the successful evaluation of many prospects and the importance of such amplitude information is increasing with the advent of time lapse seismic techniques. It is now widely accepted that the proper treatment of amplitudes requires seismic imaging in the form of either time or depth migration. A key factor in seismic imaging is the spatial sampling of the data and its relationship to the imaging algorithms. This presentation demonstrates that acquisition caused spatial sampling irregularity can affect the seismic imaging and perturb amplitudes. Equalization helps to balance the amplitudes, and the dealing strategy improves the imaging further when there are azimuth variations. Equalization and dealiasing can also help with the acquisition irregularities caused by shot and receiver dislocation or missing traces. 2 refs., 2 figs.
Energy Technology Data Exchange (ETDEWEB)
Broedel, Johannes [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States); Dixon, Lance J. [SLAC National Accelerator Laboratory, Stanford University, Stanford, CA (United States)
2012-07-01
Amplitudes in gauge thoeries obtain contributions from color and kinematics. While these two parts of the amplitude seem to exhibit different symmetry structures, it turns out that they can be reorganized in a way to behave equally, which leads to the so-called color-kinematic dual representations of amplitudes. Astonishingly, the existence of those representations allows squaring to related gravitational theories right away. Contrary to the Kawaii-Levellen-Tye relations, which have been used to relate gauge theories and gravity previously, this method is applicable not only to tree amplitudes but also at loop level. In this talk, the basic technique is introduced followed by a discussion of the existence of color-kinematic dual representations for amplitudes derived from gauge theory actions which are deformed by higher-operator insertions. In addition, it is commented on the implications for deformed gravitational theories.
Economic characteristics of a smaller, simpler reactor
International Nuclear Information System (INIS)
LaBar, M.; Bowers, H.
1988-01-01
Reduced load growth and heightened concern with economic risk has led to an expressed utility preference for smaller capacity additions. The Modular High Temperature Reactor (MHTGR) plant has been developed as a small, simple plant that has limited financial risk and is economically competitive with comparatively sized coal plants. Competitive economics is achieved by the simplifications made possible in a small MHTGR, reduction in the quantity of nuclear grade construction and design standardization and certification. Assessments show the MHTGR plant to have an economic advantage over coal plants for plant sizes from 270 MWe to 1080 MWe. Financial risk is limited by small unit sizes and short lead times that allow incremental deployment. Evaluations show the MHTGR incremental deployment capability to reduce negative cash flows by almost a factor of 2 relative to that required by a single large nuclear plant
Vlasov simulation of the relativistic effect on the breaking of large amplitude plasma waves
International Nuclear Information System (INIS)
Xu Hui; Sheng Zhengming; Zhang Jie
2007-01-01
The influence of relativistic and thermal effects on plasma wave breaking has been studied by solving the coupled Vlasov-Poisson equations. When the relativistic effect is not considered, the wave breaking will not occur, provided the initial perturbation is less than certain value as predicted previously, and the largest amplitude of the plasma wave will decrease with the increase of the initial temperature. When the relativistic effect is considered, wave breaking always occurs during the time evolution, irrespective of the initial perturbation amplitude. Yet the smaller the initial perturbation amplitude is, the longer is the time for wave breaking to occur. With large initial perturbations, wave breaking can always occur with the without the relativistic effect. However, the results are significantly different in the two cases. The thermal effects of electrons decrease the threshold value to initial amplitude for wave breaking and large phase velocity makes the nonlinear phenomenon occur more easily. (authors)
Marketing healthcare: lessons for smaller hospitals.
Chowdhary, N R
2000-02-01
Recently, I have noted ubiquitous trends that lead me to conclude that we are on the brink of a fundamental change in the structure of healthcare delivery. Hospitals are changing. The hospital, that enduring and pervasive organization, which for decades has delivered the vast majority of acute care services is being re-conceptualized. Administrators and executives in today's hospitals are beginning to recognize the disaffection of constituents and the necessity to change from placing their own agenda or that of their profession over the needs of the customer. A lesson that is increasingly being heeded, particularly by the leading hospitals, is that a belief in one's own importance or a feeling of invulnerability represents an anachronistic stance. No hospital today can afford to retain a view that it is more important than the patients it serves, or that it is invulnerable. The external pressures are already clear--the actors, factors and forces in the external environment are forcing hospitals to re-evaluate efficiency, effectiveness and delivery arrangements. The rise to prominence of the outcomes movement is part of this trend. The present study was an attempt to assess the practices and trends in the modern smaller hospitals as a part of their strategy to match the competitive pressures.
Indian Academy of Sciences (India)
IAS Admin
wavelength, they are called shallow water waves. In the ... Deep and intermediate water waves are dispersive as the velocity of these depends on wavelength. This is not the ..... generation processes, the finite amplitude wave theories are very ...
Real topological string amplitudes
Energy Technology Data Exchange (ETDEWEB)
Narain, K.S. [The Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, Trieste, 34151 (Italy); Piazzalunga, N. [Simons Center for Geometry and Physics, State University of New York,Stony Brook, NY, 11794-3636 (United States); International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy); Tanzini, A. [International School for Advanced Studies (SISSA) and INFN, Sez. di Trieste,via Bonomea 265, Trieste, 34136 (Italy)
2017-03-15
We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G{sub χ}, at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g{sup ′}=−χ+1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F{sub g}.
Energy Technology Data Exchange (ETDEWEB)
Gao, Yangyang; Sun, Zhilin [Ocean College, Zhejiang University, Hangzhou 310058 (China); Tan, Danielle S [Maritime Research Centre, Nanyang Technological University, Singapore 639798 (Singapore); Yu, Dingyong [College of Engineering, Ocean University of China, 266100 (China); Tan, Soon Keat, E-mail: yygao@zju.edu.cn [Nanyang Environment and Water Research Institute, Nanyang Technological University, Singapore 639798 (Singapore)
2014-04-01
The flow patterns around a cylinder oscillating freely in the wake of a larger cylinder upstream were investigated using the particle image velocimetry technique. The upstream cylinder was fixed at both ends while the downstream smaller cylinder was held by springs such that it was free to oscillate in the transverse direction. The flow patterns, amplitudes of oscillation and vortex shedding frequencies were compared with those of a single cylinder. In the presence of the upstream cylinder, the three parameters characterizing the oscillation response of the smaller cylinder—amplitude of oscillation, vortex shedding frequency and Reynolds stresses—were greatly reduced. While their magnitude increased with gap ratio, these three parameters were still smaller than the corresponding magnitudes for a single oscillating cylinder. The peak values of turbulence statistics such as Reynolds shear stress and normal stress behind the oscillating downstream cylinder were similarly reduced, and increased with gap ratios. (paper)
Abnormal Selective Attention Normalizes P3 Amplitudes in PDD
Hoeksma, Marco R.; Kemner, Chantal; Kenemans, J. Leon; van Engeland, Herman
2006-01-01
This paper studied whether abnormal P3 amplitudes in PDD are a corollary of abnormalities in ERP components related to selective attention in visual and auditory tasks. Furthermore, this study sought to clarify possible age differences in such abnormalities. Children with PDD showed smaller P3 amplitudes than controls, but no abnormalities in…
Investigating the amplitude of interactive footstep sounds and soundscape reproduction
DEFF Research Database (Denmark)
Turchet, Luca; Serafin, Stefania
2013-01-01
In this paper, we study the perception of amplitude of soundscapes and interactively generated footstep sounds provided both through headphones and a surround sound system. In particular, we investigate whether there exists a value for the amplitude of soundscapes and footstep sounds which...... of soundscapes does not significantly affect the selected amplitude of footstep sounds. Similarly, the perception of the soundscapes amplitude is not significantly affected by the selected amplitude of footstep sounds....
International Nuclear Information System (INIS)
Hansen, J.D.
1976-01-01
This article discusses the partial wave analysis of two, three and four meson systems. The difference between the two approaches, referred to as amplitude and Ascoli analysis is discussed. Some of the results obtained with these methods are shown. (B.R.H.)
Reinforcing Saccadic Amplitude Variability
Paeye, Celine; Madelain, Laurent
2011-01-01
Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we…
Light Meson Distribution Amplitudes
Arthur, R.; Brommel, D.; Donnellan, M.A.; Flynn, J.M.; Juttner, A.; de Lima, H.Pedroso; Rae, T.D.; Sachrajda, C.T.; Samways, B.
2010-01-01
We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.
Effects of strength training on mechanomyographic amplitude
International Nuclear Information System (INIS)
DeFreitas, Jason M; Beck, Travis W; Stock, Matt S
2012-01-01
The aim of the present study was to determine if the patterns of mechanomyographic (MMG) amplitude across force would change with strength training. Twenty-two healthy men completed an 8-week strength training program. During three separate testing visits (pre-test, week 4, and week 8), the MMG signal was detected from the vastus lateralis as the subjects performed isometric step muscle actions of the leg extensors from 10–100% of maximal voluntary contraction (MVC). During pre-testing, the MMG amplitude increased linearly with force to 66% MVC and then plateaued. Conversely, weeks 4 and 8 demonstrated an increase in MMG amplitude up to ∼85% of the subject's original MVC before plateauing. Furthermore, seven of the ten force levels (30–60% and 80–100%) showed a significant decrease in mean MMG amplitude values after training, which consequently led to a decrease in the slope of the MMG amplitude/force relationship. The decreases in MMG amplitude at lower force levels are indicative of hypertrophy, since fewer motor units would be required to produce the same absolute force if the motor units increased in size. However, despite the clear changes in the mean values, analyses of individual subjects revealed that only 55% of the subjects demonstrated a significant decrease in the slope of the MMG amplitude/force relationship. (paper)
Large-amplitude dust acoustic shocklets in non-Maxwellian dusty plasmas
Ali, S.; Naeem, Ismat; Mirza, Arshad M.
2017-10-01
The formation and propagation of fully nonlinear dust-acoustic (DA) waves and shocks are studied in a non-Maxwellian thermal dusty plasma which is composed of Maxwellian electrons and nonthermal energetic ions with a neutralizing background of negatively charged dust grains. For this purpose, we have solved dust dynamical equations along with quasineutrality equation by using a diagonalization matrix technique. A set of two characteristic wave equations is obtained, which admits both analytical and numerical solutions. Taylor expansion in the small-amplitude limit ( Φ ≪ 1 ) leads to nonlinear effective phase and shock speeds accounting for nonthermal energetic ions. It is numerically shown that DA pulses can be developed into DA shocklets involving the negative electrostatic potential, dust fluid velocity, and dust number density. These structures are significantly influenced by the ion-nonthermality, dust thermal correction, and temporal variations. However, the amplitudes of solitary and shock waves are found smaller in case of Cairns-distributed ions as compared to Kappa-distributed ions due to smaller linear and nonlinear effective phase speeds that cause smaller nonlinearity effects. The present results should be useful for understanding the nonlinear characteristics of large-amplitude DA excitations and nonstationary shocklets in a laboratory non-Maxwellian dusty plasma, where nonthermal energetic ions are present in addition to Maxwellian electrons.
Smaller superior temporal gyrus volume specificity in schizotypal personality disorder
Goldstein, Kim E.; Hazlett, Erin A.; New, Antonia S.; Haznedar, M. Mehmet; Newmark, Randall E.; Zelmanova, Yuliya; Passarelli, Vincent; Weinstein, Shauna R.; Canfield, Emily L.; Meyerson, David A.; Tang, Cheuk Y.; Buchsbaum, Monte S.; Siever, Larry J.
2009-01-01
Background Superior temporal gyrus (STG/BA22) volume is reduced in schizophrenia and to a milder degree in schizotypal personality disorder (SPD), representing a less severe disorder in the schizophrenia-spectrum. SPD and Borderline personality disorder (BPD) are severe personality disorders characterized by social and cognitive dysfunction. However, while SPD is characterized by social withdrawal/anhedonia, BPD is marked by hyper-reactivity to interpersonal stimuli and hyper-emotionality. This is the first morphometric study to directly compare SPD and BPD patients in temporal volume. Methods We compared three age-gender- and education-matched groups: 27 unmedicated SPD individuals with no BPD traits, 52 unmedicated BPD individuals with no SPD traits, and 45 healthy controls. We examined gray matter volume of frontal and temporal lobe Brodmann areas (BAs), and dorsal/ventral amygdala from 3T magnetic resonance imaging. Results In the STG, an auditory association area reported to be dysfunctional in SPD and BPD, the SPD patients had significantly smaller volume than healthy controls and BPD patients. No group differences were found between BPD patients and controls. Smaller BA22 volume was associated with greater symptom severity in SPD patients. Reduced STG volume may be an important endophenotype for schizophrenia-spectrum disorders. SPD is distinct from BPD in terms of STG volume abnormalities which may reflect different underlying pathophysiological mechanisms and could help discriminate between them. PMID:19473820
The amplitude of quantum field theory
International Nuclear Information System (INIS)
Medvedev, B.V.; Pavlov, V.P.; Polivanov, M.K.; Sukhanov, A.D.
1989-01-01
General properties of the transition amplitude in axiomatic quantum field theory are discussed. Bogolyubov's axiomatic method is chosen as the variant of the theory. The axioms of this method are analyzed. In particular, the significance of the off-shell extension and of the various forms of the causality condition are examined. A complete proof is given of the existence of a single analytic function whose boundary values are the amplitudes of all channels of a process with given particle number
The Application of Systemic Safety for Smaller Nuclear Installations
International Nuclear Information System (INIS)
Ward, J.
2016-01-01
This paper will provide an outline of ARPANSA’s approach to systemic safety as applied to smaller hazard nuclear installations. It will describe ARPANSA’s effort to enable licence holders to better understand the principles of systemic safety so that they may make improvements for themselves. In regard to human and organizational factors, inspections are more often used to highlight areas where performance can be improved to meet best practice rather than strictly as a compliance tool. This takes account of a graded, risk informed approach and is undertaken in a collaborative way that places a premium on openness, clarity, reliability and efficiency. The paper will discuss the challenges faced by the approach, and how ARPANSA is currently managing these. It will describe ARPANSA’s regulatory guidance and inspection processes. The significant stages in ARPANSA development of the systemic approach are provided briefly in the following paragraphs.
Corrections to the box diagram amplitude due to kaon mass
International Nuclear Information System (INIS)
Datta, A.; Kumbhakar, D.
1985-08-01
The K 0 -anti-K 0 mixing amplitude is calculated without using the standard zero external momentum approximation. The resulting corrections are numerically significant for the real part of the amplitude. In the imaginary part of the amplitude the effects of similar corrections are less important. Implications for Δmsub(k) and epsilon are discussed. (author)
Directory of Open Access Journals (Sweden)
Mónica eLindín
2013-11-01
Full Text Available It has been suggested that changes in some event-related potential (ERP parameters associated with controlled processing of stimuli could be used as biomarkers of amnestic mild cognitive impairment (aMCI. However, data regarding the suitability of ERP components associated with automatic and involuntary processing of stimuli for this purpose are not conclusive. In the present study, we studied the Mismatch Negativity (MMN component, a correlate of the automatic detection of changes in the acoustic environment, in healthy adults and adults with aMCI (age range: 50-87 years. An auditory-visual attention-distraction task, in two evaluations separated by an interval of between 18 and 24 months, was used. In both evaluations, the MMN amplitude was significantly smaller in the aMCI adults than in the control adults. In the first evaluation, such differences were observed for the subgroup of adults between 50 and 64 years of age, but not for the subgroup of 65 years and over. In the aMCI adults, the MMN amplitude was significantly smaller in the second evaluation than in the first evaluation, but no significant changes were observed in the control adult group. The MMN amplitude was found to be a sensitive and specific biomarker of aMCI, in both the first and second evaluation.
Ten Indicators of Vitality in Smaller Academic Libraries
Pappas, David
2009-01-01
This paper provides a means of quickly ascertaining the relative health of smaller academic libraries by presenting a top ten list of vitality indicators. The list is based on an observational convenience sampling of thirty smaller academic libraries across the United States. The indicators making the list were those which appeared most often in…
13 CFR 107.710 - Requirement to finance smaller enterprises.
2010-01-01
... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Requirement to finance smaller enterprises. 107.710 Section 107.710 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL... Small Business for Sbic Financing § 107.710 Requirement to finance smaller enterprises. Your Portfolio...
Designing a Smaller Power Inverter: the Google Littlebox Challenge - Text
Version | Energy Systems Integration Facility | NREL Designing a Smaller Power Inverter: the Google Littlebox Challenge - Text Version er Power Inverter: the Google Littlebox Challenge - Text Version Below is the text version for the Designing a Smaller Power Inverter: the Google Littlebox
Directory of Open Access Journals (Sweden)
Anja S Euser
Full Text Available BACKGROUND: Although P300 amplitude reductions constitute a persistent finding in children of addicted parents, relatively little is known about the specificity of this finding. The major aim of this study was to investigate the association between parental rearing, adverse life events, stress-reactivity, substance use and psychopathology on the one hand, and P300 amplitude in response to both target and novel distracter stimuli on the other hand. Moreover, we assessed whether risk group status (i.e., having a parental history of Substance Use Disorders [SUD] uniquely contributed to P300 amplitude variation above and beyond these other variables. METHODS: Event-related potentials were recorded in high-risk adolescents with a parental history of SUD (HR;n=80 and normal-risk controls (NR;n=100 while performing a visual Novelty Oddball paradigm. Stress-evoked cortisol levels were assessed and parenting, life adversities, substance use and psychopathology were examined by using self-reports. RESULTS: HR adolescents displayed smaller P300 amplitudes in response to novel- and to target stimuli than NR controls, while the latter only approached significance. Interestingly, the effect of having a parental history of SUD on target-P300 disappeared when all other variables were taken into account. Externalizing problem behavior was a powerful predictor of target-P300. In contrast, risk group status uniquely predicted novelty-P300 amplitude reductions above and beyond all other factors. CONCLUSION: Overall, the present findings suggest that the P300 amplitude reduction to novel stimuli might be a more specific endophenotype for SUD than the target-P300 amplitude. This pattern of results underscores the importance of conducting multifactorial assessments when examining important cognitive processes in at-risk adolescents.
Unifying relations for scattering amplitudes
Cheung, Clifford; Shen, Chia-Hsien; Wen, Congkao
2018-02-01
We derive new amplitudes relations revealing a hidden unity among a wideranging variety of theories in arbitrary spacetime dimensions. Our results rely on a set of Lorentz invariant differential operators which transmute physical tree-level scattering amplitudes into new ones. By transmuting the amplitudes of gravity coupled to a dilaton and two-form, we generate all the amplitudes of Einstein-Yang-Mills theory, Dirac-Born-Infield theory, special Galileon, nonlinear sigma model, and biadjoint scalar theory. Transmutation also relates amplitudes in string theory and its variants. As a corollary, celebrated aspects of gluon and graviton scattering like color-kinematics duality, the KLT relations, and the CHY construction are inherited traits of the transmuted amplitudes. Transmutation recasts the Adler zero as a trivial consequence of the Weinberg soft theorem and implies new subleading soft theorems for certain scalar theories.
Hidden beauty in multiloop amplitudes
International Nuclear Information System (INIS)
Cachazo, Freddy; Spradlin, Marcus; Volovich, Anastasia
2006-01-01
Planar L-loop maximally helicity violating amplitudes in N = 4 supersymmetric Yang-Mills theory are believed to possess the remarkable property of satisfying iteration relations in L. We propose a simple new method for studying iteration relations for four-particle amplitudes which involves the use of certain linear differential operators and eliminates the need to fully evaluate any loop integrals. We carry out this procedure in explicit detail for the two-loop amplitude and prove that this method can be applied to any multiloop integral, allowing a conjectured iteration relation for any given amplitude to be tested up to polynomials in logarithms
International Nuclear Information System (INIS)
Bern, Z.
2004-01-01
Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes
International Nuclear Information System (INIS)
Bern, Z.; Dixon, L.J.; Kosower, D.A.
2004-01-01
Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes
Automated Polarimetry with Smaller Aperture Telescopes: The ROVOR Observatory
Directory of Open Access Journals (Sweden)
Joseph Moody
2017-10-01
Full Text Available To better understand possible blazar jet mechanisms and morphologies, brighter prototypical objects are regularly monitored for variability in optical broad-band light. If the monitoring filters are polarized, the position angles and polarization percentages can be measured and their evolution monitored over time. However, building up a statistically significant time base of polarization parameters requires the arduous task of monitoring sources for months or years to catch and follow interesting events such as flares. Fortunately, monitoring an object is easily done using remotely operated or robotic telescopes. The Remote Observatory for Variable Object Research (ROVOR is a small-aperture telescope that has monitored blazars in broad-band Johnson filters since 2009. Calibration data using a set of four plane-polarized filters suggest that it is suitable for polarimetric monitoring as well. We have successfully collected data on CTA 102 and are encouraged at the prospects of monitoring it and other similar objects. Long-term monitoring campaigns are a scientifically and educationally-effective use of underutilized smaller-aperture telescopes.
More, smaller bacteria in response to ocean's warming?
Moran, Xose Anxelu G.
2015-06-10
Heterotrophic bacteria play a major role in organic matter cycling in the ocean. Although the high abundances and relatively fast growth rates of coastal surface bacterioplankton make them suitable sentinels of global change, past analyses have largely overlooked this functional group. Here, time series analysis of a decade of monthly observations in temperate Atlantic coastal waters revealed strong seasonal patterns in the abundance, size and biomass of the ubiquitous flow-cytometric groups of low (LNA) and high nucleic acid (HNA) content bacteria. Over this relatively short period, we also found that bacterioplankton cells were significantly smaller, a trend that is consistent with the hypothesized temperature-driven decrease in body size. Although decadal cell shrinking was observed for both groups, it was only LNA cells that were strongly coherent, with ecological theories linking temperature, abundance and individual size on both the seasonal and interannual scale. We explain this finding because, relative to their HNA counterparts, marine LNA bacteria are less diverse, dominated by members of the SAR11 clade. Temperature manipulation experiments in 2012 confirmed a direct effect of warming on bacterial size. Concurrent with rising temperatures in spring, significant decadal trends of increasing standing stocks (3% per year) accompanied by decreasing mean cell size (-1% per year) suggest a major shift in community structure, with a larger contribution of LNA bacteria to total biomass. The increasing prevalence of these typically oligotrophic taxa may severely impact marine foodwebs and carbon fluxes by an overall decrease in the efficiency of the biological pump. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Direct amplitude detuning measurement with ac dipole
Directory of Open Access Journals (Sweden)
S. White
2013-07-01
Full Text Available In circular machines, nonlinear dynamics can impact parameters such as beam lifetime and could result in limitations on the performance reach of the accelerator. Assessing and understanding these effects in experiments is essential to confirm the accuracy of the magnetic model and improve the machine performance. A direct measurement of the machine nonlinearities can be obtained by characterizing the dependency of the tune as a function of the amplitude of oscillations (usually defined as amplitude detuning. The conventional technique is to excite the beam to large amplitudes with a single kick and derive the tune from turn-by-turn data acquired with beam position monitors. Although this provides a very precise tune measurement it has the significant disadvantage of being destructive. An alternative, nondestructive way of exciting large amplitude oscillations is to use an ac dipole. The perturbation Hamiltonian in the presence of an ac dipole excitation shows a distinct behavior compared to the free oscillations which should be correctly taken into account in the interpretation of experimental data. The use of an ac dipole for direct amplitude detuning measurement requires careful data processing allowing one to observe the natural tune of the machine; the feasibility of such a measurement is demonstrated using experimental data from the Large Hadron Collider. An experimental proof of the theoretical derivations based on measurements performed at injection energy is provided as well as an application of this technique at top energy using a large number of excitations on the same beam.
Energy Technology Data Exchange (ETDEWEB)
Lam, C.S., E-mail: Lam@physics.mcgill.ca [Department of Physics, McGill University, Montreal, Q.C., H3A 2T8 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Yao, York-Peng, E-mail: yyao@umich.edu [Department of Physics, The University of Michigan Ann Arbor, MI 48109 (United States)
2016-06-15
The Cachazo–He–Yuan (CHY) formula for on-shell scattering amplitudes is extended off-shell. The off-shell amplitudes (amputated Green's functions) are Möbius invariant, and have the same momentum poles as the on-shell amplitudes. The working principles which drive the modifications to the scattering equations are mainly Möbius covariance and energy momentum conservation in off-shell kinematics. The same technique is also used to obtain off-shell massive scalars. A simple off-shell extension of the CHY gauge formula which is Möbius invariant is proposed, but its true nature awaits further study.
Multiscalar production amplitudes beyond threshold
Argyres, E N; Kleiss, R H
1993-01-01
We present exact tree-order amplitudes for $H^* \\to n~H$, for final states containing one or two particles with non-zero three-momentum, for various interaction potentials. We show that there are potentials leading to tree amplitudes that satisfy unitarity, not only at threshold but also in the above kinematical configurations and probably beyond. As a by-product, we also calculate $2\\to n$ tree amplitudes at threshold and show that for the unbroken $\\phi^4$ theory they vanish for $n>4~$, for the Standard Model Higgs they vanish for $n\\ge 3~$ and for a model potential, respecting tree-order unitarity, for $n$ even and $n>4~$. Finally, we calculate the imaginary part of the one-loop $1\\to n$ amplitude in both symmetric and spontaneously broken $\\phi^4$ theory.
Scattering amplitudes in gauge theories
Henn, Johannes M
2014-01-01
At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...
Amplitude damping of vortex modes
CSIR Research Space (South Africa)
Dudley, Angela L
2010-09-01
Full Text Available An interferometer, mimicking an amplitude damping channel for vortex modes, is presented. Experimentally the action of the channel is in good agreement with that predicted theoretically. Since we can characterize the action of the channel on orbital...
Motivic amplitudes and cluster coordinates
International Nuclear Information System (INIS)
Golden, J.K.; Goncharov, A.B.; Spradlin, M.; Vergu, C.; Volovich, A.
2014-01-01
In this paper we study motivic amplitudes — objects which contain all of the essential mathematical content of scattering amplitudes in planar SYM theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. We find that the cluster structure on the kinematic configuration space Conf n (ℙ 3 ) underlies the structure of motivic amplitudes. Specifically, we compute explicitly the coproduct of the two-loop seven-particle MHV motivic amplitude A 7,2 M and find that like the previously known six-particle amplitude, it depends only on certain preferred coordinates known in the mathematics literature as cluster X-coordinates on Conf n (ℙ 3 ). We also find intriguing relations between motivic amplitudes and the geometry of generalized associahedrons, to which cluster coordinates have a natural combinatoric connection. For example, the obstruction to A 7,2 M being expressible in terms of classical polylogarithms is most naturally represented by certain quadrilateral faces of the appropriate associahedron. We also find and prove the first known functional equation for the trilogarithm in which all 40 arguments are cluster X-coordinates of a single algebra. In this respect it is similar to Abel’s 5-term dilogarithm identity
Particle Distribution Modification by Low Amplitude Modes
International Nuclear Information System (INIS)
White, R.B.; Gorelenkov, N.; Heidbrink, W.W.; Van Zeeland, M.A.
2009-01-01
Modification of a high energy particle distribution by a spectrum of low amplitude modes is investigated using a guiding center code. Only through resonance are modes effective in modifying the distribution. Diagnostics are used to illustrate the mode-particle interaction and to find which effects are relevant in producing significant resonance, including kinetic Poincare plots and plots showing those orbits with time averaged mode-particle energy transfer. Effects of pitch angle scattering and drag are studied, as well as plasma rotation and time dependence of the equilibrium and mode frequencies. A specific example of changes observed in a DIII-D deuterium beam distribution in the presence of low amplitude experimentally validated Toroidal Alfven (TAE) eigenmodes and Reversed Shear Alfven (RSAE) eigenmodes is examined in detail. Comparison with experimental data shows that multiple low amplitude modes can account for significant modification of high energy beam particle distributions. It is found that there is a stochastic threshold for beam profile modification, and that the experimental amplitudes are only slightly above this threshold.
Trends and patterns in smaller companies: The Danish perspective
DEFF Research Database (Denmark)
Ulhøi, John Parm; Madsen, Henning
2000-01-01
This paper presents the empirical findings of a recent survey of Danish managers, with a special focus on managers in smaller companies. The survey, called the 'Danish Management Barometer', is part of a joint research programme between the Aarhus School of Business and the Danish Association...
The Underreported Use of Integrated Marketing Communication by Smaller Businesses.
Johnson, Ed
This research suggests integrated marketing communication (IMC) is widely used by small business. In a survey of Midwest businesses, it was found that smaller business tend to integrate their marketing communication to the same extent as do larger businesses. Their advertising, P.R., and sales promotion are as likely to present a unified message,…
Healthcare security staffing for smaller facilities: where science meets art.
Warren, Bryan
2013-01-01
Obtaining effective security resourcing and staffing for smaller healthcare facilities presents many difficulties, according to the author In this article, he provides guidance to security practitioners on taking existing data and translating it into a language that administration will understand and appreciate.
Library Homepage Design at Smaller Bachelor of Arts Institutions
Jones, Scott L.; Leonard, Kirsten
2011-01-01
This study examined the homepages of the libraries of 175 smaller bachelor of arts institutions, coding for the presence of 98 design elements. By reporting and examining the frequency of these features, the authors noted what is and is not common practice at these libraries. They found that only fourteen elements were present on at least half of…
Implementation Study of Smaller Learning Communities. Final Report
Bernstein, Lawrence; Millsap, Mary Ann; Schimmenti, Jennifer; Page, Lindsay
2008-01-01
The Smaller Learning Communities (SLC) program was established in response to growing national concerns about students too often lost and alienated in large, impersonal high schools, as well as concerns about school safety and low levels of achievement and graduation for many students. Authorized under the "Elementary and Secondary Education Act,"…
International Nuclear Information System (INIS)
French, J.R.J.; Robinson, P.J.
1982-01-01
Irradiating elm billets with gamma rays had a significant effect in reducing the attractancy of these billets to inflight adults of the smaller elm bark beetle Scolytus multistriatus (Marsham). The temperature at which the fresh billets were stored prior to the beetle exposure had little effect. Irradiated billets, irrespective of storage temperature, had significantly fewer holes than the freshly cut billets. There were significant differences associated with the location of the billets in the field, but these differences were smaller than those associated with irradiation. (orig.) [de
Nonsinglet pentagons and NMHV amplitudes
Directory of Open Access Journals (Sweden)
A.V. Belitsky
2015-07-01
Full Text Available Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.
Nonsinglet pentagons and NMHV amplitudes
Energy Technology Data Exchange (ETDEWEB)
Belitsky, A.V., E-mail: andrei.belitsky@asu.edu
2015-07-15
Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.
Cluster polylogarithms for scattering amplitudes
International Nuclear Information System (INIS)
Golden, John; Paulos, Miguel F; Spradlin, Marcus; Volovich, Anastasia
2014-01-01
Motivated by the cluster structure of two-loop scattering amplitudes in N=4 Yang-Mills theory we define cluster polylogarithm functions. We find that all such functions of weight four are made up of a single simple building block associated with the A 2 cluster algebra. Adding the requirement of locality on generalized Stasheff polytopes, we find that these A 2 building blocks arrange themselves to form a unique function associated with the A 3 cluster algebra. This A 3 function manifests all of the cluster algebraic structure of the two-loop n-particle MHV amplitudes for all n, and we use it to provide an explicit representation for the most complicated part of the n = 7 amplitude as an example. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Cluster algebras in mathematical physics’. (paper)
Topological amplitudes in string theory
International Nuclear Information System (INIS)
Antoniadis, I.; Taylor, T.R.
1993-07-01
We show that certain type II string amplitudes at genus g are given by the topological partition F g discussed recently by Bershadsky, Cecotti, Ooguri and Vafa. These amplitudes give rise to a term in the four-dimensional effective action of the form Σ g F g W 2g , where W is the chiral superfield of N = 2 supergravitational multiplet. The holomorphic anomaly of F g is related to non-localities of the effective action due to the propagation of massless states. This result generalizes the holomorphic anomaly of the one loop case which is known to lead to non-harmonic gravitational couplings. (author). 22 refs, 2 figs
International Nuclear Information System (INIS)
Mandelstam, S.
1986-06-01
Work on the derivation of an explicit perturbation series for string and superstring amplitudes is reviewed. The light-cone approach is emphasized, but some work on the Polyakov approach is also mentioned, and the two methods are compared. The calculation of the measure factor is outlined in the interacting-string picture
Scattering Amplitudes from Intersection Theory.
Mizera, Sebastian
2018-04-06
We use Picard-Lefschetz theory to prove a new formula for intersection numbers of twisted cocycles associated with a given arrangement of hyperplanes. In a special case when this arrangement produces the moduli space of punctured Riemann spheres, intersection numbers become tree-level scattering amplitudes of quantum field theories in the Cachazo-He-Yuan formulation.
Positivity of spin foam amplitudes
International Nuclear Information System (INIS)
Baez, John C; Christensen, J Daniel
2002-01-01
The amplitude for a spin foam in the Barrett-Crane model of Riemannian quantum gravity is given as a product over its vertices, edges and faces, with one factor of the Riemannian 10j symbols appearing for each vertex, and simpler factors for the edges and faces. We prove that these amplitudes are always nonnegative for closed spin foams. As a corollary, all open spin foams going between a fixed pair of spin networks have real amplitudes of the same sign. This means one can use the Metropolis algorithm to compute expectation values of observables in the Riemannian Barrett-Crane model, as in statistical mechanics, even though this theory is based on a real-time (e iS ) rather than imaginary-time e -S path integral. Our proof uses the fact that when the Riemannian 10j symbols are nonzero, their sign is positive or negative depending on whether the sum of the ten spins is an integer or half-integer. For the product of 10j symbols appearing in the amplitude for a closed spin foam, these signs cancel. We conclude with some numerical evidence suggesting that the Lorentzian 10j symbols are always nonnegative, which would imply similar results for the Lorentzian Barrett-Crane model
Employing Helicity Amplitudes for Resummation
Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.
2015-01-01
Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are
Scattering amplitudes in gauge theories
Energy Technology Data Exchange (ETDEWEB)
Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Plefka, Jan C. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik
2014-03-01
First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.
Scattering amplitudes in gauge theories
International Nuclear Information System (INIS)
Henn, Johannes M.; Plefka, Jan C.
2014-01-01
First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.
Employing helicity amplitudes for resummation
International Nuclear Information System (INIS)
Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.
2015-08-01
Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.
Discontinuity formulas for multiparticle amplitudes
International Nuclear Information System (INIS)
Stapp, H.P.
1976-03-01
It is shown how discontinuity formulas for multiparticle scattering amplitudes are derived from unitarity and analyticity. The assumed analyticity property is the normal analytic structure, which was shown to be equivalent to the space-time macrocausality condition. The discontinuity formulas to be derived are the basis of multi-particle fixed-t dispersion relations
Distribution amplitudes of vector mesons
Energy Technology Data Exchange (ETDEWEB)
Braun, V.M. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Broemmel, D. [Deutsches Elektronen-Synchrotron, Hamburg (Germany); Goeckeler, M. [Regensburg Univ. (DE). Inst. fuer Theoretische Physik] (and others)
2007-11-15
Results are presented for the lowest moment of the distribution amplitude for the K{sup *} vector meson. Both longitudinal and transverse moments are investigated. We use two flavours of O(a) improved Wilson fermions, together with a non-perturbative renormalisation of the matrix element. (orig.)
DEFF Research Database (Denmark)
Romanovsky, G.; Xydis, G.; Mutale, J.
2011-01-01
a number of specific historical, technical and economic reasons that significantly influenced the ability of the smaller size RES/DG to participate in the electricity market and in provision of balancing services in accordance with the UK National Grid requirements. This paper discusses some perspectives...
Scruncher phase and amplitude control
International Nuclear Information System (INIS)
DeHaven, R.A.; Morris, C.L.; Johnson, R.; Davis, J.; O'Donnell, J.M.
1992-01-01
The analog controller for phase and amplitude control of a 402.5 MHz super conducting cavity is described in this paper. The cavity is a single cell with niobium explosively bonded to a copper cavity. It is used as an energy compressor for pions at the Clinton P. Anderson Meson Physics Facility (LAMPF). The controller maintains cavity frequency to within 4 degrees in phase of the LAMPF beam frequency. Field amplitude is maintained to within 2 percent. This control is accomplished at critical coupling (Q load of 1 x 10 9 ) with the use of only a 30 watt rf amplifier for accelerating fields of 6 MV/m. The design includes the use of piezoelectric crystals for fast resonance control. Three types of control, self excited, VCO, and a reference frequency driven, were tried on this cavity and we present a comparison of their performance. (Author) 4 figs., ref
SCRUNCHER phase and amplitude control
International Nuclear Information System (INIS)
DeHaven, R.A.; Morris, C.L.; Johnson, R.; Davis, J.; O'Donnell, J.M.
1992-01-01
The analog controller for phase and amplitude control of a 402.5 MHz super conducting cavity is described in this paper. The cavity is a single cell with niobium explosively bonded to a copper cavity. It is used as an energy compressor for pions at the Clinton P. Anderson Meson Physics Facility (LAMPF). The controller maintains cavity frequency to within 4 degrees in phase of the LAMPF beam frequency. Field amplitude is maintained to within 2 percent. This control is accomplished at critical coupling (Q loaded of 1 x 10 9 ) with the use of only a 30 watt rf amplifier for accelerating fields of 6 MV/m. The design includes the use of piezoelectric crystals for fast resonance control. Three types of control, self excited VCO, and a reference frequency driven, were tried on this cavity and we present a comparison of their performance
Periodic instantons and scattering amplitudes
International Nuclear Information System (INIS)
Khlebnikov, S.Yu.; Rubakov, V.A.; Tinyakov, P.G.
1991-04-01
We discuss the role of periodic euclidean solutions with two turning points and zero winding number (periodic instantons) in instanton induced processes below the sphaleron energy E sph . We find that the periodic instantons describe certain multiparticle scattering events leading to the transitions between topologically distinct vacua. Both the semiclassical amplitudes and inital and final states of these transitions are determined by the periodic instantons. Furthermore, the corresponding probabilities are maximal among all states of given energy. We show that at E ≤ E sph , the periodic instantons can be approximated by infinite chains of ordinary instantons and anti-instantons, and they naturally emerge as deformations of the zero energy instanton. In the framework of 2d abelian Higgs model and 4d electroweak theory we show, however, that there is not obvious relation between periodic instantons and two-particle scattering amplitudes. (orig.)
Determination of the scattering amplitude
International Nuclear Information System (INIS)
Gangal, A.D.; Kupsch, J.
1984-01-01
The problem to determine the elastic scattering amplitude from the differential cross-section by the unitarity equation is reexamined. We prove that the solution is unique and can be determined by a convergent iteration if the parameter lambda=sin μ of Newton and Martin is bounded by lambda 2 approx.=0.86. The method is based on a fixed point theorem for holomorphic mappings in a complex Banach space. (orig.)
Pulse amplitude modulated chlorophyll fluorometer
Greenbaum, Elias; Wu, Jie
2015-12-29
Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.
Semiclassical approach to fidelity amplitude
International Nuclear Information System (INIS)
García-Mata, Ignacio; Vallejos, Raúl O; Wisniacki, Diego A
2011-01-01
The fidelity amplitude (FA) is a quantity of paramount importance in echo-type experiments. We use semiclassical theory to study the average FA for quantum chaotic systems under external perturbation. We explain analytically two extreme cases: the random dynamics limit - attained approximately by strongly chaotic systems - and the random perturbation limit, which shows a Lyapunov decay. Numerical simulations help us to bridge the gap between both the extreme cases. (paper)
On the Construction of Scattering Amplitudes for Spinning Massless Particles
Berends, F A
1997-01-01
In this paper the general form of scattering amplitudes for massless particles with equal spins s ($s s \\to s s$) or unequal spins ($s_a s_b \\to s_a s_b$) are derived. The imposed conditions are that the amplitudes should have the lowest possible dimension, have propagators of dimension $m^{-2}$, and obey gauge invariance. It is shown that the number of momenta required for amplitudes involving particles with s > 2 is higher than the number implied by 3-vertices for higher spin particles derived in the literature. Therefore, the dimension of the coupling constants following from the latter 3-vertices has a smaller power of an inverse mass than our results imply. Consequently, the 3-vertices in the literature cannot be the first interaction terms of a gauge-invariant theory. When no spins s > 2 are present in the process the known QCD, QED or (super) gravity amplitudes are obtained from the above general amplitudes.
Time-amplitude converter; Convertisseur temps-amplitude
Energy Technology Data Exchange (ETDEWEB)
Banner, M [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires
1961-07-01
It is normal in high energy physics to measure the time of flight of a particle in order to determine its mass. This can be done by the method which consists in transforming the time measurement into an analysis of amplitude, which is easier; a time-amplitude converter has therefore been built for this purpose. The apparatus here described uses a double grid control tube 6 BN 6 whose resolution time, as measured with a pulse generator, is 5 x 10{sup -11} s. The analysis of the response of a particle counter, made up of a scintillator and a photomultiplier, indicates that a time of resolution of 5 x 10{sup -10} s. can be obtained. A time of this order of magnitude is obtained experimentally with the converter. This converter has been used in the study of the time of flight of particles in a secondary beam of the accelerator Saturne. It has thus been possible to measure the energy spectrum of {pi}-mesons, of protons, and of deutons emitted from a polyethylene target bombarded by 1,4 and 2 GeV protons. (author) [French] Pour determiner la masse d'une particule, il est courant, en physique des hautes energies, de mesurer le temps de vol de cette particule. Cela peut etre fait par la methode qui consiste a transformer la mesure d'un temps en une analyse d'amplitude, plus aisee; aussi a-t-on, a cet effet, cree un convertisseur temps-amplitude. L'appareillage decrit dans cet article utilise un tube a double grille de commande 6 BN 6 dont le temps de resolution mesure avec un generateur d'impulsion est de 5.10{sup -11} s. L'analyse de la reponse d'un compteur de particules, constitue par un scintillateur et un photomultiplicateur, indique qu'un temps de resolution de 5.10{sup -10} s peut etre obtenu. Un temps de cet ordre est atteint experimentalement avec le convertisseur. Ce convertisseur a servi a l'etude du temps de vol des particules dans un faisceau secondaire de l'accelerateur Saturne. On a mesure ainsi le spectre d'energie des mesons {pi}, des protons, des deutons
Energy Technology Data Exchange (ETDEWEB)
Kim, Juntae; Helgeson, Matthew E., E-mail: helgeson@engineering.ucsb.edu [Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California 93106 (United States); Merger, Dimitri; Wilhelm, Manfred [Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany)
2014-09-01
We investigate yielding in a colloidal gel that forms a heterogeneous structure, consisting of a two-phase bicontinuous network of colloid-rich domains of fractal clusters and colloid-poor domains. Combining large amplitude oscillatory shear measurements with simultaneous small and ultra-small angle neutron scattering (rheo-SANS/USANS), we characterize both the nonlinear mechanical processes and strain amplitude-dependent microstructure underlying yielding. We observe a broad, three-stage yielding process that evolves over an order of magnitude in strain amplitude between the onset of nonlinearity and flow. Analyzing the intracycle response as a sequence of physical processes reveals a transition from elastic straining to elastoplastic thinning (which dominates in region I) and eventually yielding (which evolves through region II) and flow (which saturates in region III), and allows quantification of instantaneous nonlinear parameters associated with yielding. These measures exhibit significant strain rate amplitude dependence above a characteristic frequency, which we argue is governed by poroelastic effects. Correlating these results with time-averaged rheo-USANS measurements reveals that the material passes through a cascade of structural breakdown from large to progressively smaller length scales. In region I, compression of the fractal domains leads to the formation of large voids. In regions II and III, cluster-cluster correlations become increasingly homogeneous, suggesting breakage and eventually depercolation of intercluster bonds at the yield point. All significant structural changes occur on the micron-scale, suggesting that large-scale rearrangements of hundreds or thousands of particles, rather than the homogeneous rearrangement of particle-particle bonds, dominate the initial yielding of heterogeneous colloidal gels.
Amplitude modulation reflectometer for FTU
International Nuclear Information System (INIS)
Zerbini, M.; Buratti, P.; Centioli, C.; Amadeo, P.
1995-06-01
Amplitude modulation (AM) reflectometry is a modification of the classical frequency sweep technique which allows to perform unambiguous phase delay measurements. An eight-channel AM reflectometer has been realized for the measurement of density profiles on the FTU tokamak in the range. The characteristics of the instrument have been determined in extensive laboratory tests; particular attention has been devoted to the effect of interference with parasitic reflections. The reflectometer is now operating on FTU. Some examples of the first experimental data are discussed
Superstring amplitudes and contact interactions
International Nuclear Information System (INIS)
Greensite, J.
1987-08-01
We show that scattering amplitudes computed from light-cone superstring field theory are divergent at tree level. The divergences can be eliminated, and supersymmetry restored, by the addition of certain counter terms to the light-cone Hamiltonian. These counter terms have the form of local contact interactions, whose existence we had previously deduced on grounds of vacuum stability, and closure of the super-Poincare algebra. The quartic contact interactions required in Type I and Type IIB superstring theories are constructed in detail. (orig.)
Forward amplitude in pion deuteron
International Nuclear Information System (INIS)
Ferreira, E.M.; Munguia, G.A.P.; Rosa, L.P.; Thome, Z.D.
1979-06-01
The data on total cross section for πd scattering is analysed in terms of a single scattering calculation with Fermi motion dependence, in order to obtain a criterion to fix the value of the energy entering the two body meson nucleon amplitude. It is found that the prescription derived from the non-relativistic three body kinematics gives reasonable results. The introduction of a shift in the energy value, possibly representing nuclear binding effects, leads to a very good fitting of the data. The results are compared with those obtained in direct calculations of Faddeev equations and with the Brueckner model of fixed scatterers. (Author) [pt
Open string topological amplitudes and gaugino masses
International Nuclear Information System (INIS)
Antoniadis, I.; Narain, K.S.; Taylor, T.R.
2005-09-01
We discuss the moduli-dependent couplings of the higher derivative F-terms (TrW 2 ) h-1 , where W is the gauge N =1 chiral superfield. They are determined by the genus zero topological partition function F (0,h) , on a world-sheet with h boundaries. By string duality, these terms are also related to heterotic topological amplitudes studied in the past, with the topological twist applied only in the left-moving supersymmetric sector of the internal N =(2,0) superconformal field theory. The holomorphic anomaly of these couplings relates them to terms of the form Π n (TrW 2 ) h-2 , where Π's represent chiral projections of non-holomorphic functions of chiral superfields. An important property of these couplings is that they violate R-symmetry for h ≥ 3. As a result, once supersymmetry is broken by D-term expectation values, (TrW 2 ) 2 generates gaugino masses that can be hierarchically smaller than the scalar masses, behaving as m 1/2 ∼ m 0 4 in string units. Similarly, ΠTrW 2 generates Dirac masses for non-chiral brane fermions, of the same order of magnitude. This mechanism can be used for instance to obtain fermion masses at the TeV scale for scalar masses as high as m 0 ∼ O (10 13 ) GeV. We present explicit examples in toroidal string compactifications with intersecting D-branes. (author)
Covariant amplitudes in Polyakov string theory
International Nuclear Information System (INIS)
Aoyama, H.; Dhar, A.; Namazie, M.A.
1986-01-01
A manifestly Lorentz-covariant and reparametrization-invariant procedure for computing string amplitudes using Polyakov's formulation is described. Both bosonic and superstring theories are dealt with. The computation of string amplitudes is greatly facilitated by this formalism. (orig.)
Amplitude Modulated Sinusoidal Signal Decomposition for Audio Coding
DEFF Research Database (Denmark)
Christensen, M. G.; Jacobson, A.; Andersen, S. V.
2006-01-01
In this paper, we present a decomposition for sinusoidal coding of audio, based on an amplitude modulation of sinusoids via a linear combination of arbitrary basis vectors. The proposed method, which incorporates a perceptual distortion measure, is based on a relaxation of a nonlinear least......-squares minimization. Rate-distortion curves and listening tests show that, compared to a constant-amplitude sinusoidal coder, the proposed decomposition offers perceptually significant improvements in critical transient signals....
Grassmannian geometry of scattering amplitudes
Arkani-Hamed, Nima; Cachazo, Freddy; Goncharov, Alexander; Postnikov, Alexander; Trnka, Jaroslav
2016-01-01
Outlining a revolutionary reformulation of the foundations of perturbative quantum field theory, this book is a self-contained and authoritative analysis of the application of this new formulation to the case of planar, maximally supersymmetric Yang–Mills theory. The book begins by deriving connections between scattering amplitudes and Grassmannian geometry from first principles before introducing novel physical and mathematical ideas in a systematic manner accessible to both physicists and mathematicians. The principle players in this process are on-shell functions which are closely related to certain sub-strata of Grassmannian manifolds called positroids - in terms of which the classification of on-shell functions and their relations becomes combinatorially manifest. This is an essential introduction to the geometry and combinatorics of the positroid stratification of the Grassmannian and an ideal text for advanced students and researchers working in the areas of field theory, high energy physics, and the...
Determination of backward pion nucleon scattering amplitudes
International Nuclear Information System (INIS)
Pietarinen, E.
1978-04-01
Backward C(sup(+-))πN amplitudes are determined from πN→Nπ and NantiN→2π differential cross sections in such a way that they are consistent with the analyticity properties and information of the unphysical ππ→NantiN amplitudes. Combining the result with forward C(sup(+-)) amplitudes positive and negative parity resonances are extracted. An error analysis of the amplitudes is performed. (author)
Molecular dynamics simulation of amplitude modulation atomic force microscopy
International Nuclear Information System (INIS)
Hu, Xiaoli; Martini, Ashlie; Egberts, Philip; Dong, Yalin
2015-01-01
Molecular dynamics (MD) simulations were used to model amplitude modulation atomic force microscopy (AM-AFM). In this novel simulation, the model AFM tip responds to both tip–substrate interactions and to a sinusoidal excitation signal. The amplitude and phase shift of the tip oscillation observed in the simulation and their variation with tip–sample distance were found to be consistent with previously reported trends from experiments and theory. These simulation results were also fit to an expression enabling estimation of the energy dissipation, which was found to be smaller than that in a corresponding experiment. The difference was analyzed in terms of the effects of tip size and substrate thickness. Development of this model is the first step toward using MD to gain insight into the atomic-scale phenomena that occur during an AM-AFM measurement. (paper)
Ethnic differences in electrocardiographic amplitude measurements
International Nuclear Information System (INIS)
Mansi, Ishak A.; Nash, Ira S.
2004-01-01
There is a controversy regarding ethnic differences in electrocardiographic (ECG) patterns because of the potentially confounding socioeconomic, nutritional, environmental and occupational factors. We reviewed the first 1000 medical files of a multiethnic community, where all individuals shared similar living conditions. Only healthy adults age 15 to 60 years were included. Wave amplitudes were measured manually from the standard 12lead ECG. Minnesota coding was used. ECG from 597 subjects were included in the study: 350 Saudi Arabians, 95 Indians, 17 Sri-Lankans, 39 Filipinos, and 57 Caucasians; 349 were men. the mean +-SD of Sokolow-Lyon voltage (SLV) in men was signifcantly different among ethnic groups (2.9+-0.86, 2.64+-0.79, 2.73+-0.72, 3.23+-0.61, 2.94+-0.6, 2.58+-0.79 mV, P=0.0006, for Saudi's, Indians, Jordanians, Filipinos, Sri-Lankans, and Caucasians, respectively). SLV was similar among ethnic groups in women. The prevalence of early transition pattern was also different among ethnic groups in men but not women (15.8%, 34.6%, 17.9%, 21.7%, 35.3%, 26.8% in Suadi, Indian, Jordanian, Filipino, Sri-Lankan, and Caucasian, respectively, P=0.037). T wave amplitude was significantly different among ethnic groups in selected lead. ECG wave amplitude differs with ethnic region even when other factors are similar. Using SLV of 3.5 mV as a criterion may overestimate the incidence of left ventricular hypertrophy in some ethnic groups. The pattern of high R wave in lead V1is common in healthy adults in certain ethnic groups. T wave height differs with ethnic origin and sex. (author)
Complex amplitude reconstruction by iterative amplitude-phase retrieval algorithm with reference
Shen, Cheng; Guo, Cheng; Tan, Jiubin; Liu, Shutian; Liu, Zhengjun
2018-06-01
Multi-image iterative phase retrieval methods have been successfully applied in plenty of research fields due to their simple but efficient implementation. However, there is a mismatch between the measurement of the first long imaging distance and the sequential interval. In this paper, an amplitude-phase retrieval algorithm with reference is put forward without additional measurements or priori knowledge. It gets rid of measuring the first imaging distance. With a designed update formula, it significantly raises the convergence speed and the reconstruction fidelity, especially in phase retrieval. Its superiority over the original amplitude-phase retrieval (APR) method is validated by numerical analysis and experiments. Furthermore, it provides a conceptual design of a compact holographic image sensor, which can achieve numerical refocusing easily.
High-Arctic butterflies become smaller with rising temperatures
DEFF Research Database (Denmark)
Bowden, Joseph James; Eskildsen, Anne; Hansen, Rikke Reisner
2015-01-01
size but long growing seasons could also increase body size as was recently shown in an Arctic spider species. Here, we present the longest known time series on body size variation in two High-Arctic butterfly species: Boloria chariclea and Colias hecla. We measured wing length of nearly 4500...... individuals collected annually between 1996 and 2013 from Zackenberg, Greenland and found that wing length significantly decreased at a similar rate in both species in response to warmer summers. Body size is strongly related to dispersal capacity and fecundity and our results suggest that these Arctic...
Kepler observations of the high-amplitude δ Scuti star V2367 Cyg
DEFF Research Database (Denmark)
Balona, L. A.; Lenz, P.; Antoci, V.
2012-01-01
We analyse Kepler observations of the high-amplitude δ Scuti (HADS) star V2367 Cyg (KIC 9408694). The variations are dominated by a mode with frequency f1= 5.6611 d−1. Two other independent modes with f2= 7.1490 d−1 and f3= 7.7756 d−1 have amplitudes an order of magnitude smaller than f1. Nearly...... all the light variation is due to these three modes and their combination frequencies, but several hundred other frequencies of very low amplitude are also present. The amplitudes of the principal modes may vary slightly with time. The star has twice the projected rotational velocity of any other HADS...... star, which makes it unusual. We find a correlation between the phases of the combination frequencies and their pulsation frequencies, which is not understood. Since modes of highest amplitude in HADS stars are normally radial modes, we assumed that this would also be true in this star. However...
Haigh, Sarah M; Gupta, Akshat; Barb, Scott M; Glass, Summer A F; Minshew, Nancy J; Dinstein, Ilan; Heeger, David J; Eack, Shaun M; Behrmann, Marlene
2016-08-01
Autism and schizophrenia share multiple phenotypic and genotypic markers, and there is ongoing debate regarding the relationship of these two disorders. To examine whether cortical dynamics are similar across these disorders, we directly compared fMRI responses to visual, somatosensory and auditory stimuli in adults with autism (N=15), with schizophrenia (N=15), and matched controls (N=15). All participants completed a one-back letter detection task presented at fixation (to control attention) while task-irrelevant sensory stimulation was delivered to the different modalities. We focused specifically on the response amplitudes and the variability in sensory fMRI responses of the two groups, given the evidence of greater trial-to-trial variability in adults with autism. Both autism and schizophrenia individuals showed weaker signal-to-noise ratios (SNR) in sensory-evoked responses compared to controls (d>0.42), but for different reasons. For the autism group, the fMRI response amplitudes were indistinguishable from controls but were more variable trial-to-trial (d=0.47). For the schizophrenia group, response amplitudes were smaller compared to autism (d=0.44) and control groups (d=0.74), but were not significantly more variable (dautism and is not a defining characteristic of schizophrenia, and (2) that blunted response amplitudes may be characteristic of schizophrenia. The relationship between the amplitude and the variability of cortical activity might serve as a specific signature differentiating these neurodevelopmental disorders. Identifying the neural basis of these responses and their relationship to the underlying genetic bases may substantially enlighten the understanding of both disorders. Copyright © 2016 Elsevier B.V. All rights reserved.
New Compact Accommodometer to Measure Accommodation Amplitude as a Biomarker.
Ide, Takeshi; Negishi, Kazuno; Yamaguchi, Takefumi; Hara, Shuya; Toda, Ikuko; Tsubota, Kazuo
2012-01-01
This study aimed to evaluate a newly designed compact accommodometer (CA) and compare this with a conventional accommodometer for measuring accommodation as a biomarker for aging and lifestyle. This is an observational case series. Accommodative amplitude was measured using 2 different accommodometers in 114 patients. We obtained the data of the near-point accommodation amplitude. Subsequently, we used smoking habit as an example of lifestyle-related factor to evaluate its effect on the accommodative power. The first part of the study included 60 eyes of 60 men and 54 eyes of 54 women, with a mean (SD) age of 43.8 (12.9) years (range, 18-58 years). There was a consistency within each measuring method despite a significant difference between the 2 devices (P the second part of the study, we found a significant correlation between age and accommodative amplitude both in smokers and in nonsmokers. The accommodative amplitude of the smoker group was significantly lower than that of the nonsmoker group (P the conventional accommodometer for measuring accommodative amplitude as an aging biomarker. Lifestyle factors can affect the magnitude of accommodation, which can be measured by this newly developed CA.
On the singularities of massive superstring amplitudes
International Nuclear Information System (INIS)
Foda, O.
1987-01-01
Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism. (orig.)
On the singularities of massive superstring amplitudes
Energy Technology Data Exchange (ETDEWEB)
Foda, O.
1987-06-04
Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are not terms in the perturbative expansion of physical S-matrix elements: These can be defined only with massless external states. Consistent massive amplitudes repuire an off-shell formalism.
New relations for graviton-matter amplitudes
CERN. Geneva
2018-01-01
I report on recent progress in finding compact expressions for scattering amplitudes involving gravitons and gluons as well as massive scalar and fermionic matter particles. At tree level the single graviton emission amplitudes may be expressed as linear combination of purely non-gravitational ones. At the one-loop level recent results on all four point Einstein-Yang-Mills amplitudes with at most one opposite helicity state using unitarity methods are reported.
Analytical properties of multiple production amplitudes
Energy Technology Data Exchange (ETDEWEB)
Medvedev, B V; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki; AN SSSR, Moscow. Matematicheskij Inst.)
1984-05-01
Local analytical properties of amplitudes 2..-->..3 and 2..-->..4 are studied. The amplitudes are shown to be analytical functions of total and partial energies at fixed momentum transfers in the neighbourhood of any physical point on the energy shell 14 (for the 2..-->..3 case) and 242 (for the 2..-->..4 case) boundary values are expressed through the amplitudes of real processes.
DVCS amplitude with kinematical twist-3 terms
International Nuclear Information System (INIS)
Radyushkin, A.V.; Weiss, C.
2000-01-01
The authors compute the amplitude of deeply virtual Compton scattering (DVCS) using the calculus of QCD string operators in coordinate representation. To restore the electromagnetic gauge invariance (transversality) of the twist-2 amplitude they include the operators of twist-3 which appear as total derivatives of twist-2 operators. The results are equivalent to a Wandzura-Wilczek approximation for twist-3 skewed parton distributions. They find that this approximation gives a finite result for the amplitude of a longitudinally polarized virtual photon, while the amplitude for transverse polarization is divergent, i.e., factorization breaks down in this term
Amplitude structure of off-shell processes
International Nuclear Information System (INIS)
Fearing, H.W.; Goldstein, G.R.; Moravcsik, M.J.
1984-01-01
The structure of M matrices, or scattering amplitudes, and of potentials for off-shell processes is discussed with the objective of determining how one can obtain information on off-shell amplitudes of a process in terms of the physical observables of a larger process in which the first process is embedded. The procedure found is inevitably model dependent, but within a particular model for embedding, a determination of the physically measurable amplitudes of the larger process is able to yield a determination of the off-shell amplitudes of the embedded process
Dispersion relation analysis of the neutral kaon regeneration amplitude in carbon
Angelopoulos, Angelos; Locher, M P; Markushin, V E; Aslanides, Elie; Backenstoss, Gerhard; Bargassa, P; Behnke, O; Benelli, A; Bertin, V; Blanc, F; Bloch, P; Carlson, P J; Carroll, M; Cawley, E; Chertok, M B; Danielsson, M; Dejardin, M; Derré, J; Ealet, A; Eleftheriadis, C; Faravel, L; Festcher, W; Fidecaro, Maria; Filipcic, A; Francis, D; Fry, J; Gabathuler, Erwin; Gamet, R; Gerber, H J; Go, A; Haselden, A; Hayman, P J; Henry-Coüannier, F; Hollander, R W; Jon-And, K; Kettle, P R; Kokkas, P; Kreuger, R; Le Gac, R; Leimgruber, F; Mandic, I; Manthos, N; Marel, Gérard; Mikuz, M; Miller, J; Montanet, François; Müller, A; Nakada, Tatsuya; Pagels, B; Papadopoulos, I M; Pavlopoulos, P; Polivka, G; Rickenbach, R; Roberts, B L; Ruf, T; Schäfer, M; Schaller, L A; Schietinger, T; Schopper, A; Tauscher, Ludwig; Thibault, C; Touchard, F; Touramanis, C; van Eijk, C W E; Vlachos, S; Weber, P; Wigger, O; Wolter, M; Zavrtanik, D; Zimmerman, D
1999-01-01
We apply a forward dispersion relation to the regeneration amplitude for kaon scattering on /sup 12/C using all available data. The CPLEAR data at low energies allow the determination of the net contribution from the subthreshold $9 region which turns out to be much smaller than earlier evaluations, solving a long standing puzzle. (29 refs).
International Nuclear Information System (INIS)
Christoskov, I.D.; Vapirev, E.I.
1990-01-01
An alternative way of presenting the time-dependent amplitudes and intensities of radiation, corresponding to resonant absorption and scattering experiments, is developed. Infinite series of Bessel functions with complex coefficients are replaced by simple for calculation definite integrals and the number of Bessel function calls is reduced to one per a tabulation point. Thus the calculational effort for experimental data processing becomes smaller
Detecting Novelty and Significance
Ferrari, Vera; Bradley, Margaret M.; Codispoti, Maurizio; Lang, Peter J.
2013-01-01
Studies of cognition often use an “oddball” paradigm to study effects of stimulus novelty and significance on information processing. However, an oddball tends to be perceptually more novel than the standard, repeated stimulus as well as more relevant to the ongoing task, making it difficult to disentangle effects due to perceptual novelty and stimulus significance. In the current study, effects of perceptual novelty and significance on ERPs were assessed in a passive viewing context by presenting repeated and novel pictures (natural scenes) that either signaled significant information regarding the current context or not. A fronto-central N2 component was primarily affected by perceptual novelty, whereas a centro-parietal P3 component was modulated by both stimulus significance and novelty. The data support an interpretation that the N2 reflects perceptual fluency and is attenuated when a current stimulus matches an active memory representation and that the amplitude of the P3 reflects stimulus meaning and significance. PMID:19400680
Energy Technology Data Exchange (ETDEWEB)
Saeki, T [Japan National Oil Corporation, Tokyo (Japan). Technology Research Center
1996-10-01
For the seismic reflection method conducted on the ground surface, generator and geophone are set on the surface. The observed waveforms are affected by the ground surface and surface layer. Therefore, it is required for discussing physical properties of the deep underground to remove the influence of surface layer, preliminarily. For the surface consistent amplitude correction, properties of the generator and geophone were removed by assuming that the observed waveforms can be expressed by equations of convolution. This is a correction method to obtain records without affected by the surface conditions. In response to analysis and correction of waveforms, wavelet conversion was examined. Using the amplitude patterns after correction, the significant signal region, noise dominant region, and surface wave dominant region would be separated each other. Since the amplitude values after correction of values in the significant signal region have only small variation, a representative value can be given. This can be used for analyzing the surface consistent amplitude correction. Efficiency of the process can be enhanced by considering the change of frequency. 3 refs., 5 figs.
Howard, J. E.
2014-12-01
This study focusses on improving methods of accounting for atmospheric effects on infrasound amplitudes observed on arrays at regional distances in the southwestern United States. Recordings at ranges of 150 to nearly 300 km from a repeating ground truth source of small HE explosions are used. The explosions range in actual weight from approximately 2000-4000 lbs. and are detonated year-round which provides signals for a wide range of atmospheric conditions. Three methods of correcting the observed amplitudes for atmospheric effects are investigated with the data set. The first corrects amplitudes for upper stratospheric wind as developed by Mutschlecner and Whitaker (1999) and uses the average wind speed between 45-55 km altitudes in the direction of propagation to derive an empirical correction formula. This approach was developed using large chemical and nuclear explosions and is tested with the smaller explosions for which shorter wavelengths cause the energy to be scattered by the smaller scale structure of the atmosphere. The second approach isa semi-empirical method using ray tracing to determine wind speed at ray turning heights where the wind estimates replace the wind values in the existing formula. Finally, parabolic equation (PE) modeling is used to predict the amplitudes at the arrays at 1 Hz. The PE amplitudes are compared to the observed amplitudes with a narrow band filter centered at 1 Hz. An analysis is performed of the conditions under which the empirical and semi-empirical methods fail and full wave methods must be used.
Automation of loop amplitudes in numerical approach
International Nuclear Information System (INIS)
Fujimoto, J.; Ishikawa, T.; Shimizu, Y.; Kato, K.; Nakazawa, N.; Kaneko, T.
1997-01-01
An automatic calculating system GRACE-L1 of one-loop Feynman amplitude is reviewed. This system can be applied to 2 to 2-body one-loop processes. A sample calculation of 2 to 3-body one-loop amplitudes is also presented. (orig.)
On the singularities of massive superstring amplitudes
Foda, O.
1987-01-01
Superstring one-loop amplitudes with massive external states are shown to be in general ill-defined due to internal on-shell propagators. However, we argue that since any massive string state (in the uncompactified theory) has a finite lifetime to decay into massless particles, such amplitudes are
Scattering Amplitudes via Algebraic Geometry Methods
DEFF Research Database (Denmark)
Søgaard, Mads
Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized...
Full amplitude models of 15 day Cepheids
International Nuclear Information System (INIS)
Cogan, B.C.; Cox, A.N.; King, D.S.
1980-01-01
Numerical models of Cepheids have been computed with a range of effective temperatures and compositions. The amplitudes increase if the helium abundance increases or if the effective temperature decreases. The latter effect is contrary to observational data. The models also exhibit velocity amplitudes which are much lower than those observed
Helicity amplitudes for matter-coupled gravity
International Nuclear Information System (INIS)
Aldrovandi, R.; Novaes, S.F.; Spehler, D.
1992-07-01
The Weyl-van der Waerden spinor formalism is applied to the evaluation of helicity invariant amplitudes in the framework of linearized gravitation. The graviton couplings to spin-0, 1 - 2 , 1, and 3 - 2 particles are given, and, to exhibit the reach of this method, the helicity amplitudes for the process electron + positron → photon + graviton are obtained. (author)
New relations for gauge-theory amplitudes
International Nuclear Information System (INIS)
Bern, Z.; Carrasco, J. J. M.; Johansson, H.
2008-01-01
We present an identity satisfied by the kinematic factors of diagrams describing the tree amplitudes of massless gauge theories. This identity is a kinematic analog of the Jacobi identity for color factors. Using this we find new relations between color-ordered partial amplitudes. We discuss applications to multiloop calculations via the unitarity method. In particular, we illustrate the relations between different contributions to a two-loop four-point QCD amplitude. We also use this identity to reorganize gravity tree amplitudes diagram by diagram, offering new insight into the structure of the Kawai-Lewellen-Tye (KLT) relations between gauge and gravity tree amplitudes. This insight leads to similar but novel relations. We expect this to be helpful in higher-loop studies of the ultraviolet properties of gravity theories.
Changes in ENSO amplitude under climate warming and cooling
Wang, Yingying; Luo, Yiyong; Lu, Jian; Liu, Fukai
2018-05-01
The response of ENSO amplitude to climate warming and cooling is investigated using the Community Earth System Model (CESM), in which the warming and cooling scenarios are designed by adding heat fluxes of equal amplitude but opposite sign onto the ocean surface, respectively. Results show that the warming induces an increase of the ENSO amplitude but the cooling gives rise to a decrease of the ENSO amplitude, and these changes are robust in statistics. A mixed layer heat budget analysis finds that the increasing (decreasing) SST tendency under climate warming (cooling) is mainly due to an enhancement (weakening) of dynamical feedback processes over the equatorial Pacific, including zonal advective (ZA) feedback, meridional advective (MA) feedback, thermocline (TH) feedback, and Ekman (EK) feedback. As the climate warms, a wind anomaly of the same magnitude across the equatorial Pacific can induce a stronger zonal current change in the east (i.e., a stronger ZA feedback), which in turn produces a greater weakening of upwelling (i.e., a stronger EK feedback) and thus a larger thermocline change (i.e., a stronger TH feedback). In response to the climate warming, in addition, the MA feedback is also strengthened due to an enhancement of the meridional SST gradient around the equator resulting from a weakening of the subtropical cells (STCs). It should be noted that the weakened STCs itself has a negative contribution to the change of the MA feedback which, however, appears to be secondary. And vice versa for the cooling case. Bjerknes linear stability (BJ) index is also evaluated for the linear stability of ENSO, with remarkably larger (smaller) BJ index found for the warming (cooling) case.
Radiocarbon evidence for a smaller oceanic carbon dioxide sink than previously believed
Hesshaimer, Vago; Heimann, Martin; Levin, Ingeborg
1994-07-01
RADIOCARBON produced naturally in the upper atmosphere or arti-ficially during nuclear weapons testing is the main tracer used to validate models of oceanic carbon cycling, in particular the exchange of carbon dioxide with the atmosphere1-3 and the mixing parameters within the ocean itself4-7. Here we test the overall consistency of exchange fluxes between all relevant compartments in a simple model of the global carbon cycle, using measurements of the long-term tropospheric CO2 concentration8 and radiocarbon composition9-12, the bomb 14C inventory in the stratosphere13,14 and a compilation of bomb detonation dates and strengths15. We find that to balance the budget, we must invoke an extra source to account for 25% of the generally accepted uptake of bomb 14C by the oceans3. The strength of this source decreases from 1970 onwards, with a characteristic timescale similar to that of the ocean uptake. Significant radiocarbon transport from the remote high stratosphere and significantly reduced uptake of bomb 14C by the biosphere can both be ruled out by observational constraints. We therefore conclude that the global oceanic bomb 14C inventory should be revised downwards. A smaller oceanic bomb 14C inventory also implies a smaller oceanic radiocarbon penetration depth16, which in turn implies that the oceans take up 25% less anthropogenic CO2 than had previously been believed.
Radial convection of finite ion temperature, high amplitude plasma blobs
DEFF Research Database (Denmark)
Wiesenberger, M.; Madsen, Jens; Kendl, Alexander
2014-01-01
We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line......-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross...
Light-cone distribution amplitudes of the baryon octet
Energy Technology Data Exchange (ETDEWEB)
Bali, Gunnar S. [Institut für Theoretische Physik, Universität Regensburg,Universitätsstraße 31, D-93040 Regensburg (Germany); Department of Theoretical Physics, Tata Institute of Fundamental Research,Homi Bhabha Road, Mumbai 400005 (India); Braun, Vladimir M.; Göckeler, Meinulf; Gruber, Michael; Hutzler, Fabian; Schäfer, Andreas; Schiel, Rainer W.; Simeth, Jakob; Söldner, Wolfgang [Institut für Theoretische Physik, Universität Regensburg,Universitätsstraße 31, D-93040 Regensburg (Germany); Sternbeck, Andre [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena,Max-Wien-Platz 1, D-07743 Jena (Germany); Wein, Philipp [Institut für Theoretische Physik, Universität Regensburg,Universitätsstraße 31, D-93040 Regensburg (Germany)
2016-02-10
We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using N{sub f}=2+1 flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to 222 MeV. Significant SU(3) flavor symmetry violation effects in the shape of the distribution amplitudes are observed.
Light-cone distribution amplitudes of the baryon octet
International Nuclear Information System (INIS)
Bali, Gunnar S.; Braun, Vladimir M.; Göckeler, Meinulf; Gruber, Michael; Hutzler, Fabian; Schäfer, Andreas; Schiel, Rainer W.; Simeth, Jakob; Söldner, Wolfgang; Sternbeck, Andre; Wein, Philipp
2016-01-01
We present results of the first ab initio lattice QCD calculation of the normalization constants and first moments of the leading twist distribution amplitudes of the full baryon octet, corresponding to the small transverse distance limit of the associated S-wave light-cone wave functions. The P-wave (higher twist) normalization constants are evaluated as well. The calculation is done using N_f=2+1 flavors of dynamical (clover) fermions on lattices of different volumes and pion masses down to 222 MeV. Significant SU(3) flavor symmetry violation effects in the shape of the distribution amplitudes are observed.
Li, Hao; Li, Haowen; Yue, Haiyan; Wang, Wen; Yu, Lanbing; ShuoWang; Cao, Yong; Zhao, Jizong
2017-07-01
As it grows in size, an intracranial aneurysm (IA) is prone to rupture. In this study, we compared two extreme groups of IAs, ruptured IAs (RIAs) smaller than 10 mm and un-ruptured IAs (UIAs) larger than 10 mm, to investigate the genes involved in the facilitation and prevention of IA rupture. The aneurismal walls of 6 smaller saccular RIAs (size smaller than 10 mm), 6 larger saccular UIAs (size larger than 10 mm) and 12 paired control arteries were obtained during surgery. The transcription profiles of these samples were studied by microarray analysis. RT-qPCR was used to confirm the expression of the genes of interest. In addition, functional group analysis of the differentially expressed genes was performed. Between smaller RIAs and larger UIAs, 101 genes and 179 genes were significantly over-expressed, respectively. In addition, functional group analysis demonstrated that the up-regulated genes in smaller RIAs mainly participated in the cellular response to metal ions and inorganic substances, while most of the up-regulated genes in larger UIAs were involved in inflammation and extracellular matrix (ECM) organization. Moreover, compared with control arteries, inflammation was up-regulated and muscle-related biological processes were down-regulated in both smaller RIAs and larger UIAs. The genes involved in the cellular response to metal ions and inorganic substances may facilitate the rupture of IAs. In addition, the healing process, involving inflammation and ECM organization, may protect IAs from rupture.
Amplitude of Accommodation and its Relation to Refractive Errors
Directory of Open Access Journals (Sweden)
Abraham Lekha
2005-01-01
Full Text Available Aims: To evaluate the relationship between amplitude of accommodation and refractive errors in the peri-presbyopic age group. Materials and Methods: Three hundred and sixteen right eyes of 316 consecutive patients in the age group 35-50 years who attended our outpatient clinic were studied. Emmetropes, hypermetropes and myopes with best-corrected visual acuity of 6/6 J1 in both eyes were included. The amplitude of accommodation (AA was calculated by measuring the near point of accommodation (NPA. In patients with more than ± 2 diopter sphere correction for distance, the NPA was also measured using appropriate soft contact lenses. Results: There was a statistically significant difference in AA between myopes and hypermetropes ( P P P P P P >0.5. Conclusion: Our study showed higher amplitude of accommodation among myopes between 35 and 44 years compared to emmetropes and hypermetropes
Holographic corrections to meson scattering amplitudes
Energy Technology Data Exchange (ETDEWEB)
Armoni, Adi; Ireson, Edwin, E-mail: 746616@swansea.ac.uk
2017-06-15
We compute meson scattering amplitudes using the holographic duality between confining gauge theories and string theory, in order to consider holographic corrections to the Veneziano amplitude and associated higher-point functions. The generic nature of such computations is explained, thanks to the well-understood nature of confining string backgrounds, and two different examples of the calculation in given backgrounds are used to illustrate the details. The effect we discover, whilst only qualitative, is re-obtainable in many such examples, in four-point but also higher point amplitudes.
Amplitude-Mode Dynamics of Polariton Condensates
International Nuclear Information System (INIS)
Brierley, R. T.; Littlewood, P. B.; Eastham, P. R.
2011-01-01
We study the stability of collective amplitude excitations in nonequilibrium polariton condensates. These excitations correspond to renormalized upper polaritons and to the collective amplitude modes of atomic gases and superconductors. They would be present following a quantum quench or could be created directly by resonant excitation. We show that uniform amplitude excitations are unstable to the production of excitations at finite wave vectors, leading to the formation of density-modulated phases. The physical processes causing the instabilities can be understood by analogy to optical parametric oscillators and the atomic Bose supernova.
Hidden simplicity of gauge theory amplitudes
Energy Technology Data Exchange (ETDEWEB)
Drummond, J M, E-mail: drummond@lapp.in2p3.f [LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux, Cedex (France)
2010-11-07
These notes were given as lectures at the CERN Winter School on Supergravity, Strings and Gauge Theory 2010. We describe the structure of scattering amplitudes in gauge theories, focussing on the maximally supersymmetric theory to highlight the hidden symmetries which appear. Using the Britto, Cachzo, Feng and Witten (BCFW) recursion relations we solve the tree-level S-matrix in N=4 super Yang-Mills theory and describe how it produces a sum of invariants of a large symmetry algebra. We review amplitudes in the planar theory beyond tree level, describing the connection between amplitudes and Wilson loops, and discuss the implications of the hidden symmetries.
Source-Space Cross-Frequency Amplitude-Amplitude Coupling in Tinnitus
Directory of Open Access Journals (Sweden)
Oliver Zobay
2015-01-01
Full Text Available The thalamocortical dysrhythmia (TCD model has been influential in the development of theoretical explanations for the neurological mechanisms of tinnitus. It asserts that thalamocortical oscillations lock a region in the auditory cortex into an ectopic slow-wave theta rhythm (4–8 Hz. The cortical area surrounding this region is hypothesized to generate abnormal gamma (>30 Hz oscillations (“edge effect” giving rise to the tinnitus percept. Consequently, the model predicts enhanced cross-frequency coherence in a broad range between theta and gamma. In this magnetoencephalography study involving tinnitus and control cohorts, we investigated this prediction. Using beamforming, cross-frequency amplitude-amplitude coupling (AAC was computed within the auditory cortices for frequencies (f1,f2 between 2 and 80 Hz. We find the AAC signal to decompose into two distinct components at low (f1,f230 Hz frequencies, respectively. Studying the correlation of AAC with several key covariates (age, hearing level (HL, tinnitus handicap and duration, and HL at tinnitus frequency, we observe a statistically significant association between age and low-frequency AAC. Contrary to the TCD predictions, however, we do not find any indication of statistical differences in AAC between tinnitus and controls and thus no evidence for the predicted enhancement of cross-frequency coupling in tinnitus.
Analytic continuation of dual Feynman amplitudes
International Nuclear Information System (INIS)
Bleher, P.M.
1981-01-01
A notion of dual Feynman amplitude is introduced and a theorem on the existence of analytic continuation of this amplitude from the convergence domain to the whole complex is proved. The case under consideration corresponds to massless power propagators and the analytic continuation is constructed on the propagators powers. Analytic continuation poles and singular set of external impulses are found explicitly. The proof of the theorem on the existence of analytic continuation is based on the introduction of α-representation for dual Feynman amplitudes. In proving, the so-called ''trees formula'' and ''trees-with-cycles formula'' are established that are dual by formulation to the trees and 2-trees formulae for usual Feynman amplitudes. (Auth.)
Amplitude-Integrated EEG in the Newborn
Directory of Open Access Journals (Sweden)
J Gordon Millichap
2008-11-01
Full Text Available Th value of amplitude-integrated electroencephalography (aEEG in the newborn is explored by researchers at Washington University, St Louis; Wilhelmina Children’s Hospital, Utrecht, Netherlands; and Uppsala University Hospital, Sweden.
Effective string theory and QCD scattering amplitudes
International Nuclear Information System (INIS)
Makeenko, Yuri
2011-01-01
QCD string is formed at distances larger than the confinement scale and can be described by the Polchinski-Strominger effective string theory with a nonpolynomial action, which has nevertheless a well-defined semiclassical expansion around a long-string ground state. We utilize modern ideas about the Wilson-loop/scattering-amplitude duality to calculate scattering amplitudes and show that the expansion parameter in the effective string theory is small in the Regge kinematical regime. For the amplitudes we obtain the Regge behavior with a linear trajectory of the intercept (d-2)/24 in d dimensions, which is computed semiclassically as a momentum-space Luescher term, and discuss an application to meson scattering amplitudes in QCD.
Scattering Amplitudes via Algebraic Geometry Methods
Søgaard, Mads; Damgaard, Poul Henrik
This thesis describes recent progress in the understanding of the mathematical structure of scattering amplitudes in quantum field theory. The primary purpose is to develop an enhanced analytic framework for computing multiloop scattering amplitudes in generic gauge theories including QCD without Feynman diagrams. The study of multiloop scattering amplitudes is crucial for the new era of precision phenomenology at the Large Hadron Collider (LHC) at CERN. Loop-level scattering amplitudes can be reduced to a basis of linearly independent integrals whose coefficients are extracted from generalized unitarity cuts. We take advantage of principles from algebraic geometry in order to extend the notion of maximal cuts to a large class of two- and three-loop integrals. This allows us to derive unique and surprisingly compact formulae for the coefficients of the basis integrals. Our results are expressed in terms of certain linear combinations of multivariate residues and elliptic integrals computed from products of ...
HIGH PERFORMANCE PIAA CORONAGRAPHY WITH COMPLEX AMPLITUDE FOCAL PLANE MASKS
International Nuclear Information System (INIS)
Guyon, Olivier; Martinache, Frantz; Belikov, Ruslan; Soummer, Remi
2010-01-01
We describe a coronagraph approach where the performance of a Phase-Induced Amplitude Apodization (PIAA) coronagraph is improved by using a partially transmissive phase-shifting focal plane mask and a Lyot stop. This approach combines the low inner working angle offered by phase mask coronagraphy, the full throughput and uncompromized angular resolution of the PIAA approach, and the design flexibility of Apodized Pupil Lyot Coronagraph. A PIAA complex mask coronagraph (PIAACMC) is fully described by the focal plane mask size, or, equivalently, its complex transmission which ranges from 0 (opaque) to -1 (phase shifting). For all values of the transmission, the PIAACMC theoretically offers full on-axis extinction and 100% throughput at large angular separations. With a pure phase focal plane mask (complex transmission = -1), the PIAACMC offers 50% throughput at 0.64 λ/D while providing total extinction of an on-axis point source. This performance is very close to the 'fundamental performance limit' of coronagraphy derived from first principles. For very high contrast level, imaging performance with PIAACMC is in practice limited by the angular size of the on-axis target (usually a star). We show that this fundamental limitation must be taken into account when choosing the optimal value of the focal plane mask size in the PIAACMC design. We show that the PIAACMC enables visible imaging of Jupiter-like planets at ∼1.2 λ/D from the host star, and can therefore offer almost three times more targets than a PIAA coronagraph optimized for this type of observation. We find that for visible imaging of Earth-like planets, the PIAACMC gain over a PIAA is probably much smaller, as coronagraphic performance is then strongly constrained by stellar angular size. For observations at 'low' contrast (below ∼ 10 8 ), the PIAACMC offers significant performance enhancement over PIAA. This is especially relevant for ground-based high contrast imaging systems in the near-IR, where
Effective gluon interactions from superstring disk amplitudes
Energy Technology Data Exchange (ETDEWEB)
Oprisa, D.
2006-05-15
In this thesis an efficient method for the calculation of the N-point tree-level string amplitudes is presented. Furthermore it is shown that the six-gluon open-superstring disk amplitude can be expressed by a basis of six triple hypergeometric functions, which encode the full {alpha}' dependence. In this connection material for obtaining the {alpha}' expansion of these functions is derived. Hereby many Euler-Zagier sums are calculated including multiple harmonic series. (HSI)
Effective gluon interactions from superstring disk amplitudes
International Nuclear Information System (INIS)
Oprisa, D.
2006-05-01
In this thesis an efficient method for the calculation of the N-point tree-level string amplitudes is presented. Furthermore it is shown that the six-gluon open-superstring disk amplitude can be expressed by a basis of six triple hypergeometric functions, which encode the full α' dependence. In this connection material for obtaining the α' expansion of these functions is derived. Hereby many Euler-Zagier sums are calculated including multiple harmonic series. (HSI)
Employing helicity amplitudes for resummation in SCET
International Nuclear Information System (INIS)
Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam
2016-05-01
Helicity amplitudes are the fundamental ingredients of many QCD calculations for multi-leg processes. We describe how these can seamlessly be combined with resummation in Soft-Collinear Effective Theory (SCET), by constructing a helicity operator basis for which the Wilson coefficients are directly given in terms of color-ordered helicity amplitudes. This basis is crossing symmetric and has simple transformation properties under discrete symmetries.
The Cepheid bump progression and amplitude equations
International Nuclear Information System (INIS)
Kovacs, G.; Buchler, J.R.
1989-01-01
It is shown that the characteristic and systematic behavior of the low-order Fourier amplitudes and phases of hydrodynamically generated radial velocity and light curves of Cepheid model sequences is very well captured not only qualitatively but also quantitatively by the amplitude equation formalism. The 2:1 resonance between the fundamental and the second overtone plays an essential role in the behavior of the models 8 refs
TouchGrid: Touchpad pointing by recursively mapping taps to smaller display regions
DEFF Research Database (Denmark)
Hertzum, Morten; Hornbæk, Kasper
2005-01-01
Touchpad devices are widely used but lacking in pointing efficiency. The TouchGrid, an instance of what we term cell cursors, replaces moving the cursor through dragging the finger on a touchpad with tapping in different regions of the touchpad. The touchpad regions are recursively mapped...... to smaller display regions and thereby enable high-precision pointing without requiring high tapping precision. In an experiment, six subjects used the TouchGrid and a standard touchpad across different numbers of targets, distances to targets, and target widths. Whereas standard touchpad operation follows...... Fitts law, target selection time with the TouchGrid is a linear function of the required number of taps. The TouchGrid was significantly faster for small targets and for tasks requiring one tap, and marginally faster for two-tap tasks. Error rates tended to be higher with the TouchGrid than...
Amplitude damping for single-qubit system with single-qubit mixed-state environment
International Nuclear Information System (INIS)
Jung, Eylee; Hwang, Mi-Ra; Ju, You Hwan; Park, D K; Kim, Hungsoo; Kim, Min-Soo; Son, Jin-Woo
2008-01-01
We study a generalized amplitude damping channel when environment is initially in the single-qubit mixed state. Representing the affine transformation of the generalized amplitude damping by a three-dimensional volume, we plot explicitly the volume occupied by the channels simulatable by a single-qubit mixed-state environment. As expected, this volume is embedded in the total volume by the channels which is simulated by a two-qubit enviroment. The volume ratio is approximately 0.08 which is much smaller than 3/8, the volume ratio for generalized depolarizing channels
Initial Breakdown Pulse Amplitudes in Intracloud and Cloud-to-Ground Lightning Flashes
Marshall, T. C.; Smith, E. M.; Stolzenburg, M.; Karunarathne, S.; Siedlecki, R. D., II
2017-12-01
This study analyzes the largest initial breakdown (IB) pulse in flashes from three storms in Florida. The study was motivated in part by the possibility that IB pulses of IC flashes may cause of terrestrial gamma-ray flashes (TGFs). The range-normalized, zero-to-peak amplitude of the largest IB pulse within each flash was determined along with its altitude, duration, and occurrence time in the flash. Appropriate data were available for 40 intracloud (IC) and 32 cloud-to-ground (CG) flashes. Histograms of the magnitude of the largest IB pulse amplitude by flash type were similar, with mean (median) values of 1.49 (1.05) V/m for IC flashes and -1.35 (-0.87) V/m for CG flashes. The mean amplitude of the largest IC IB pulses are substantially smaller (roughly an order of magnitude smaller) than the few known pulse amplitudes of TGF events and TGF candidate events. The largest IB pulse in 30 IC flashes showed a weak inverse relation between pulse amplitude and altitude. Amplitude of the largest IB pulse for 25 CG flashes showed no altitude correlation. Duration of the largest IB pulse in ICs averaged twice as long as in CGs (96 μs versus 46 μs); all of the CG durations were <100 μs. Among the ICs, there is a positive relation between largest IB pulse duration and amplitude; the linear correlation coefficient is 0.385 with outliers excluded. The largest IB pulse in IC flashes typically occurred at a longer time after the first IB pulse (average 4.1 ms) than was the case in CG flashes (average 0.6 ms). In both flash types, the largest IB pulse was the first IB pulse in about 30% of the cases.
Scattering amplitudes in open superstring theory
Energy Technology Data Exchange (ETDEWEB)
Schlotterer, Oliver
2011-07-15
The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all
Scattering amplitudes in open superstring theory
International Nuclear Information System (INIS)
Schlotterer, Oliver
2011-01-01
The present thesis deals with the theme field of the scattering amplitudes in theories of open superstrings. Especially two different formalisms for the handling of superstrings are introduced and applied for the calaculation of tree-level amplitudes - the Ramond- Neveu-Schwarz (RNS) and the Pure-Spinor (PS) formalism. The RNS approach is proved as flexible in order to describe compactification of the initially ten flat space-time dimensions to four dimensions. We solve the technical problems, which result from the interacting basing world-sheet theory with conformal symmetry. This is used to calculate phenomenologically relevant scattering amplitudes of gluons and quarks as well as production rates of massive harmonic vibrations, which were already identified as virtual exchange particles on the massless level. In the case of a low string mass scale in the range of some Tev the string-specific signatures in parton collisions can be observed in the near future in the LHC experiment at CERN and indicated as first experimental proof of the string theory. THose string effects occur universally for a wide class of string ground states respectively internal geometries and represent an elegant way to avoid the so-called landscape problem of the string theory. A further theme complex in this thesis is based on the PS formalism, which allows a manifestly supersymmetric treatment of scattering amplitudes in ten space-time dimension with sixteen supercharges. We introduce a family of superfields, which occur in massless amplitudes of the open string and can be naturally identified with diagrams of three-valued knots. Thereby we reach not only a compact superspace representation of the n-point field-theory amplitude but can also write the complete superstring n-point amplitude as minimal linear combination of partial amplitudes of the field theory as well as hypergeometric functions. The latter carry the string effects and are analyzed from different perspectives, above all
Color-Kinematics Duality for QCD Amplitudes
Johansson, Henrik
2016-01-01
We show that color-kinematics duality is present in tree-level amplitudes of quantum chromodynamics with massive flavored quarks. Starting with the color structure of QCD, we work out a new color decomposition for n-point tree amplitudes in a reduced basis of primitive amplitudes. These primitives, with k quark-antiquark pairs and (n-2k) gluons, are taken in the (n-2)!/k! Melia basis, and are independent under the color-algebra Kleiss-Kuijf relations. This generalizes the color decomposition of Del Duca, Dixon, and Maltoni to an arbitrary number of quarks. The color coefficients in the new decomposition are given by compact expressions valid for arbitrary gauge group and representation. Considering the kinematic structure, we show through explicit calculations that color-kinematics duality holds for amplitudes with general configurations of gluons and massive quarks. The new (massive) amplitude relations that follow from the duality can be mapped to a well-defined subset of the familiar BCJ relations for gluo...
Monodromy relations in higher-loop string amplitudes
Directory of Open Access Journals (Sweden)
S. Hohenegger
2017-12-01
Full Text Available New monodromy relations of loop amplitudes are derived in open string theory. We particularly study N-point (planar and non-planar one-loop amplitudes described by a world-sheet cylinder and derive a set of relations between subamplitudes of different color orderings. Various consistency checks are performed by matching Î±â²-expansions of planar and non-planar amplitudes involving elliptic iterated integrals with the resulting periods giving rise to two sets of multiple elliptic zeta values. The latter refer to the two homology cycles on the once-punctured complex elliptic curve and the monodromy equations provide relations between these two sets of multiple elliptic zeta values. Furthermore, our monodromy relations involve new objects for which we present a tentative interpretation in terms of open string scattering amplitudes in the presence of a non-trivial gauge field flux. Finally, we provide an outlook on how to generalize the new monodromy relations to the non-oriented case and beyond the one-loop level. Comparing a subset of our results with recent findings in the literature we find therein several serious issues related to the structure and significance of monodromy phases and the relevance of missed contributions from contour integrations.
Scattering amplitudes in gauge theories with and without supersymmetry
International Nuclear Information System (INIS)
Ochirov, Alexander
2014-01-01
This thesis aims at providing better understanding of the perturbative expansion of gauge theories with and without supersymmetry. At tree level, the BCFW recursion relations are analyzed with respect to their validity for general off-shell objects in Yang-Mills theory, which is a significant step away from their established zone of applicability. Unphysical poles constitute a new potential problem in addition to the boundary behavior issue, common to the on-shell case as well. For an infinite family of massive fermion currents, both obstacles are shown to be avoided under the certain conditions, which provides a natural recursion relation. At one loop, scattering amplitudes can be calculated from unitarity cuts through their expansion into known scalar integrals with free coefficients. A powerful method to obtain these coefficients, namely spinor integration, is discussed and rederived in a somewhat novel form. It is then used to compute analytically the infinite series of one-loop gluon amplitudes in N = 1 super-Yang-Mills theory with exactly three negative helicities. The final part of this thesis concerns the intriguing relationship between gluon and graviton scattering amplitudes, which involves a beautiful duality between the color and kinematic content of gauge theories. This BCJ duality is extended to include particles in the fundamental representation of the gauge group, which is shown to relieve the restriction of the BCJ construction to factorizable gravities and thus give access to amplitudes in generic (super-)gravity theories. (author) [fr
Amplitude Effects on Thrust Production for Undulatory Swimmers
Gater, Brittany; Bayandor, Javid
2017-11-01
Biological systems offer novel and efficient solutions to many engineering applications, including marine propulsion. It is of interest to determine how fish interact with the water around them, and how best to utilize the potential their methods offer. A stingray-like fin was chosen for analysis due to the maneuverability and versatility of stingrays. The stingray fin was modeled in 2D as a sinusoidal wave with an amplitude increasing from zero at the leading edge to a maximum at the trailing edge. Using this model, a parametric study was performed to examine the effects of the fin on surrounding water in CFD simulations. The results were analyzed both qualitatively, in terms of the pressure contours on the fin and vorticity in the trailing wake, and quantitatively, in terms of the resultant forces on the fin. The amplitude was found to have no effect on the average thrust during steady swimming, when the wave speed on the fin was approximately equal to the swimming speed. However, amplitude was shown to have a significant effect on thrust production when the fin was accelerating. This finding suggests that for undulatory swimmers, amplitude is less useful for controlling swimming speed, but can be used to great effect for augmenting thrust during acceleration.
Usefulness of CT-guided automatic needle biopsy of solitary pulmonary nodule smaller than 15 mm
International Nuclear Information System (INIS)
Jin, Gong Yong; Lim, Yeong Su
2004-01-01
To evaluate the usefulness of the CT-guided percutaneous lung biopsy for the solitary pulmonary nodules smaller than 15 mm in diameter. Between April 2002 and May 2003, we evaluated twenty-five patients (11 men, 14 women, mean ages: 52.5 years) who had solitary pulmonary nodules, which we could not discriminate as being benign or malignant on the CT findings. All the subjects had CT-guided percutaenous cutting needle biopsy (PCNB) performed on them at our institution. A definitive diagnosis of benignity or malignancy was established to retrospectively analyze the patient's records. We evaluated the accuracy, sensitivity, specificity and complications of PCNB for the definitive diagnosis of benignity or malignancy. The sensitivity and specificity of PCNB were determined using the Chi-square test, and the correlations with pneumothorax and emphysema after biopsy were analyzed using Spearman's rank correlation coefficient. In two nodules of the twenty-five nodules, no definitive diagnosis could be established. Of the remaining twenty-three nodules, 7 (30.4%) were malignant and 16 (69.6%) were benign. Twenty (87%) of the twenty-three definitively diagnosed nodules were correctly diagnosed with PCNB. Of the twenty nodules, 6 (30%) were malignant and 14 (70%) were benign. The sensitivity and specificity of the malignant nodules were 85.7% (6/7) and 100% (16/16), respectively. The sensitivity and specificity of the benign nodules were 87.5% (14/16) and 85.7% (6/7), respectively. Post-biopsy complication occurred in nine patients (36%): Hemoptysis (n=4, 16%) and pneumothorax (n=5, 20%). However, there was not a statistical significance between pneumothorax and emphysema after biopsy (r=0.3, p=0.15). When CT-guided percutaneous lung biopsy of the solitary pulmonary nodules smaller than 15 mm in diameter was performed without an on-site cytopathologist, we know that PCNB can yield high diagnostic accuracy and very few complications
High energy hadron spin-flip amplitude
International Nuclear Information System (INIS)
Selyugin, O.V.
2016-01-01
The high-energy part of the hadron spin-flip amplitude is examined in the framework of the new high-energy general structure (HEGS) model of the elastic hadron scattering at high energies. The different forms of the hadron spin-flip amplitude are compared in the impact parameter representation. It is shown that the existing experimental data of the proton-proton and proton-antiproton elastic scattering at high energy in the region of the diffraction minimum and at large momentum transfer give support in the presence of the energy-independent part of the hadron spin-flip amplitude with the momentum dependence proposed in the works by Galynskii-Kuraev. [ru
Scaling of saturation amplitudes in baroclinic instability
International Nuclear Information System (INIS)
Shepherd, T.G.
1994-01-01
By using finite-amplitude conservation laws for pseudomomentum and pseudoenergy, rigorous upper bounds have been derived on the saturation amplitudes in baroclinic instability for layered and continuously-stratified quasi-geostrophic models. Bounds have been obtained for both the eddy energy and the eddy potential enstrophy. The bounds apply to conservative (inviscid, unforced) flow, as well as to forced-dissipative flow when the dissipation is proportional to the potential vorticity. This approach provides an efficient way of extracting an analytical estimate of the dynamical scalings of the saturation amplitudes in terms of crucial non-dimensional parameters. A possible use is in constructing eddy parameterization schemes for zonally-averaged climate models. The scaling dependences are summarized, and compared with those derived from weakly-nonlinear theory and from baroclinic-adjustment estimates
Analytic representations of Yang–Mills amplitudes
Energy Technology Data Exchange (ETDEWEB)
Bjerrum-Bohr, N.E.J. [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Bourjaily, Jacob L., E-mail: bourjaily@nbi.ku.dk [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Damgaard, Poul H. [Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø (Denmark); Feng, Bo [Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou City, 310027 (China)
2016-12-15
Scattering amplitudes in Yang–Mills theory can be represented in the formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary projective space—fully localized on the support of the scattering equations. Because solving the scattering equations is difficult and summing over the solutions algebraically complex, a method of directly integrating the terms that appear in this representation has long been sought. We solve this important open problem by first rewriting the terms in a manifestly Möbius-invariant form and then using monodromy relations (inspired by analogy to string theory) to decompose terms into those for which combinatorial rules of integration are known. The result is the foundations of a systematic procedure to obtain analytic, covariant forms of Yang–Mills tree-amplitudes for any number of external legs and in any number of dimensions. As examples, we provide compact analytic expressions for amplitudes involving up to six gluons of arbitrary helicities.
Nonlinear (super)symmetries and amplitudes
Energy Technology Data Exchange (ETDEWEB)
Kallosh, Renata [Physics Department, Stanford University,382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States)
2017-03-07
There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E{sub 7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N≥5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.
Scattering Amplitudes and Worldsheet Models of QFTs
CERN. Geneva
2016-01-01
I will describe recent progress on the study of scattering amplitudes via ambitwistor strings and the scattering equations. Ambitwistor strings are worldsheet models of quantum field theories, inspired by string theory. They naturally lead to a representation of amplitudes based on the scattering equations. While worldsheet models and related ideas have had a wide-ranging impact on the modern study of amplitudes, their direct application at loop level is a very recent success. I will show how a major difficulty in the loop-level story, the technicalities of higher-genus Riemann surfaces, can be avoided by turning the higher-genus surface into a nodal Riemann sphere, with the nodes representing the loop momenta. I will present new formulas for the one-loop integrands of gauge theory and gravity, with or without supersymmetry, and also some two-loop results.
Relativistic amplitudes in terms of wave functions
International Nuclear Information System (INIS)
Karmanov, V.A.
1978-01-01
In the framework of the invariant diagram technique which arises at the formulation of the fueld theory on the light front the question about conditions at which the relativistic amplitudes may be expressed through the wave functions is investigated. The amplitudes obtained depend on four-vector ω, determining the light front surface. The way is shown to find such values of the four-vector ω, at which the contribution of diagrams not expressed through wave functions is minimal. The investigation carried out is equivalent to the study of the dependence of amplitudes of the old-fashioned perturbation theory in the in the infinite momentum frame on direction of the infinite momentum
Multiphoton amplitude in a constant background field
Ahmad, Aftab; Ahmadiniaz, Naser; Corradini, Olindo; Kim, Sang Pyo; Schubert, Christian
2018-01-01
In this contribution, we present our recent compact master formulas for the multiphoton amplitudes of a scalar propagator in a constant background field using the worldline fomulation of quantum field theory. The constant field has been included nonperturbatively, which is crucial for strong external fields. A possible application is the scattering of photons by electrons in a strong magnetic field, a process that has been a subject of great interest since the discovery of astrophysical objects like radio pulsars, which provide evidence that magnetic fields of the order of 1012G are present in nature. The presence of a strong external field leads to a strong deviation from the classical scattering amplitudes. We explicitly work out the Compton scattering amplitude in a magnetic field, which is a process of potential relevance for astrophysics. Our final result is compact and suitable for numerical integration.
International Nuclear Information System (INIS)
Jaeger, R.
1978-12-01
In the development of fast RF amplitude measurement systems the accuracy is limited above all by the statistical errors of measurement. This limitation is smaller in a non-d.c. measurement technique as compared with a d.c. technique and is constituted by the thermal noise of the equivalent resistances. This is the first report on such a measuring system utilizing the non-linear capacity characteristic of a varactor diode to demodulate the RF amplitude. An accuracy of the amplitude measurement of 10 -5 was achieved in the S band (2.7 GHz) at room temperature and a bandwith of 100 kHz. (orig.) [de
Amplitude-modulated fiber-ring laser
DEFF Research Database (Denmark)
Caputo, J. G.; Clausen, Carl A. Balslev; Sørensen, Mads Peter
2000-01-01
Soliton pulses generated by a fiber-ring laser are investigated by numerical simulation and perturbation methods. The mathematical modeling is based on the nonlinear Schrödinger equation with perturbative terms. We show that active mode locking with an amplitude modulator leads to a self......-starting of stable solitonic pulses from small random noise, provided the modulation depth is small. The perturbative analysis leads to a nonlinear coupled return map for the amplitude, phase, and position of the soliton pulses circulating in the fiber-ring laser. We established the validity of this approach...
Amplitude Models for Discrimination and Yield Estimation
Energy Technology Data Exchange (ETDEWEB)
Phillips, William Scott [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-09-01
This seminar presentation describes amplitude models and yield estimations that look at the data in order to inform legislation. The following points were brought forth in the summary: global models that will predict three-component amplitudes (R-T-Z) were produced; Q models match regional geology; corrected source spectra can be used for discrimination and yield estimation; three-component data increase coverage and reduce scatter in source spectral estimates; three-component efforts must include distance-dependent effects; a community effort on instrument calibration is needed.
Singularity Structure of Maximally Supersymmetric Scattering Amplitudes
DEFF Research Database (Denmark)
Arkani-Hamed, Nima; Bourjaily, Jacob L.; Cachazo, Freddy
2014-01-01
We present evidence that loop amplitudes in maximally supersymmetric (N=4) Yang-Mills theory (SYM) beyond the planar limit share some of the remarkable structures of the planar theory. In particular, we show that through two loops, the four-particle amplitude in full N=4 SYM has only logarithmic ...... singularities and is free of any poles at infinity—properties closely related to uniform transcendentality and the UV finiteness of the theory. We also briefly comment on implications for maximal (N=8) supergravity theory (SUGRA)....
Amplitude modulation detection with concurrent frequency modulation.
Nagaraj, Naveen K
2016-09-01
Human speech consists of concomitant temporal modulations in amplitude and frequency that are crucial for speech perception. In this study, amplitude modulation (AM) detection thresholds were measured for 550 and 5000 Hz carriers with and without concurrent frequency modulation (FM), at AM rates crucial for speech perception. Results indicate that adding 40 Hz FM interferes with AM detection, more so for 5000 Hz carrier and for frequency deviations exceeding the critical bandwidth of the carrier frequency. These findings suggest that future cochlear implant processors, encoding speech fine-structures may consider limiting the FM to narrow bandwidth and to low frequencies.
Gluon amplitudes as 2 d conformal correlators
Pasterski, Sabrina; Shao, Shu-Heng; Strominger, Andrew
2017-10-01
Recently, spin-one wave functions in four dimensions that are conformal primaries of the Lorentz group S L (2 ,C ) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wave functions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2 d CFT. The Britto-Cachazo-Feng-Witten (BCFW) recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis.
Precise generator of stability amplitude pulses
International Nuclear Information System (INIS)
Zhuk, N.A.; Zdesenko, Yu.G.; Kuts, V.N.
1989-01-01
A generator of stability amplitude pulses, designed for stabilization of a low-noise semiconducting spectrometer, used in investigations of 76 Ge2β-decay, is described. The generator contains a permanent-voltage source, a storage element and a switch based on a Hg relay. A thermostatic source provides a relative voltage instability less than ±5x10 -6 per 80h (standard deviation). The Hg relay is placed into a separate thermostat. The relative instability of output generator pulse amplitude does not exceed ±1.5x10 -5 per 24h
High energy multi-gluon exchange amplitudes
International Nuclear Information System (INIS)
Jaroszewicz, T.
1980-11-01
We examine perturbative high energy n-gluon exchange amplitudes calculated in the Coulomb gauge. If n exceeds the minimum required by the t-channel quantum numbers, such amplitudes are non-leading in lns. We derive a closed system of coupled integral equations for the corresponding two-particle n-gluon vertices, obtained by summing the leading powers of ln(N μ psup(μ)), where psup(μ) is the incident momentum and Nsup(μ) the gauge-defining vector. Our equations are infra-red finite, provided the external particles are colour singlets. (author)
Amplitude ratios in ρ0 leptoproductions and GPDs
Directory of Open Access Journals (Sweden)
Goloskokov S.V.
2017-01-01
Using the model results we calculate the ratio of different helicity amplitudes for a transversely polarized proton target to the leading twist longitudinal amplitude. Our results are close to the amplitude ratios measured by HERMES.
The Correlation between Electroencephalography Amplitude and Interictal Abnormalities: Audit study
Directory of Open Access Journals (Sweden)
Sami F. Al-Rawas
2014-10-01
Full Text Available Objectives: The aim of this study was to establish the relationship between background amplitude and interictal abnormalities in routine electroencephalography (EEG. Methods: This retrospective audit was conducted between July 2006 and December 2009 at the Department of Clinical Physiology at Sultan Qaboos University Hospital (SQUH in Muscat, Oman. A total of 1,718 electroencephalograms (EEGs were reviewed. All EEGs were from patients who had been referred due to epilepsy, syncope or headaches. EEGs were divided into four groups based on their amplitude: group one ≤20 μV; group two 21–35 μV; group three 36–50 μV, and group four >50 μV. Interictal abnormalities were defined as epileptiform discharges with or without associated slow waves. Abnormalities were identified during periods of resting, hyperventilation and photic stimulation in each group. Results: The mean age ± standard deviation of the patients was 27 ± 12.5 years. Of the 1,718 EEGs, 542 (31.5% were abnormal. Interictal abnormalities increased with amplitude in all four categories and demonstrated a significant association (P <0.05. A total of 56 EEGs (3.3% had amplitudes that were ≤20 μV and none of these showed interictal epileptiform abnormalities. Conclusion: EEG amplitude is an important factor in determining the presence of interictal epileptiform abnormalities in routine EEGs. This should be taken into account when investigating patients for epilepsy. A strong argument is made for considering long-term EEG monitoring in order to identify unexplained seizures which may be secondary to epilepsy. It is recommended that all tertiary institutions provide EEG telemetry services.
Slower gait, slower information processing and smaller prefrontal area in older adults.
Rosano, C.; Studenski, S.A.; Aizenstein, H.J.; Boudreau, R.M.; Longstreth Jr, W.T.; Newman, A.B.
2012-01-01
BACKGROUND: Slower gait in older adults is related to smaller volume of the prefrontal area (PFAv). The pathways underlying this association have not yet been explored. Understanding slowing gait could help improve function in older age. We examine whether the association between smaller PFAv and
Smaller Cigarette Pack as a Commitment to Smoke Less? Insights from Behavioral Economics
Marti, Joachim; Sindelar, Jody
2015-01-01
Cigarettes are commonly sold in packs of 20 units and therefore little is known about the potential impact of pack size on consumption. Using insights from behavioral economics, we suggest that cigarette packs smaller than the standard size may help some smokers cut back and/or quit, consistent with their long-term goals. Results from an online hypothetical purchase experiment conducted in a sample of US smokers reveal that over a third of smokers are willing to pay a price premium to purchase in smaller quantities. Further, a desire to quit smoking and high self-control is associated with preference for a smaller pack. While we provide some preliminary evidence that smaller packs may be beneficial to certain types of smokers, further research should be conducted to assess whether the smaller pack size should be considered in the arsenal of tobacco control policies to help current smokers quit (JEL: I18; I12; D12) PMID:26356844
Smaller Cigarette Pack as a Commitment to Smoke Less? Insights from Behavioral Economics.
Directory of Open Access Journals (Sweden)
Joachim Marti
Full Text Available Cigarettes are commonly sold in packs of 20 units and therefore little is known about the potential impact of pack size on consumption. Using insights from behavioral economics, we suggest that cigarette packs smaller than the standard size may help some smokers cut back and/or quit, consistent with their long-term goals. Results from an online hypothetical purchase experiment conducted in a sample of US smokers reveal that over a third of smokers are willing to pay a price premium to purchase in smaller quantities. Further, a desire to quit smoking and high self-control is associated with preference for a smaller pack. While we provide some preliminary evidence that smaller packs may be beneficial to certain types of smokers, further research should be conducted to assess whether the smaller pack size should be considered in the arsenal of tobacco control policies to help current smokers quit (JEL: I18; I12; D12.
Podmenik, Nadja; Leskošek, Bojan; Erčulj, Frane
2012-01-01
Our study examined whether the introduction of a smaller and lighter basketball (no. 6) affected the accuracy of female basketball players’ shots at the basket. The International Basketball Federation (FIBA) introduced a size 6 ball in the 2004/2005 season to improve the efficiency and accuracy of technical elements, primarily shots at the basket. The sample for this study included 573 European female basketball players who were members of national teams that had qualified for the senior women’s European championships in 2001, 2003, 2005 and 2007. A size 7 (larger and heavier) basketball was used by 286 players in 1,870 matches, and a size 6 basketball was used by 287 players in 1,966 matches. The players were categorised into three playing positions: guards, forwards and centres. The results revealed that statistically significant changes by year occurred only in terms of the percentage of successful free throws. With the size 6 basketball, this percentage decreased. Statistically significant differences between the playing positions were observed in terms of the percentage of field goals worth three points (between guards and forwards) and two points (between guards and centres). The results show that the introduction of the size 6 basketball did not lead to improvement in shooting accuracy (the opposite was found for free throws), although the number of three-point shots increased. PMID:23486286
Explosion Amplitude Reduction due to Fractures in Water-Saturated and Dry Granite
Stroujkova, A. F.; Leidig, M.; Bonner, J. L.
2013-12-01
Empirical observations made at the Semipalatinsk Test Site suggest that nuclear tests in the fracture zones left by previous explosions ('repeat shots') show reduced seismic amplitudes compared to the nuclear tests in virgin rocks. Likely mechanisms for the amplitude reduction in the repeat shots include increased porosity and reduced strength and elastic moduli, leading to pore closing and frictional sliding. Presence of pore water significantly decreases rock compressibility and strength, thus affecting seismic amplitudes. A series of explosion experiments were conducted in order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fracture zones of previously detonated explosions. Explosions in water-saturated granite were conducted in central New Hampshire in 2011 and 2012. Additional explosions in dry granite were detonated in Barre, VT in 2013. The amplitude reduction is different between dry and water-saturated crystalline rocks. Significant reduction in seismic amplitudes (by a factor of 2-3) in water-saturated rocks was achieved only when the repeat shot was detonated in the extensive damage zone created by a significantly larger (by a factor of 5) explosion. In case where the first and the second explosions were similar in yield, the amplitude reduction was relatively modest (5-20%). In dry rocks the amplitude reduction reached a factor of 2 even in less extensive damage zones. In addition there are differences in frequency dependence of the spectral amplitude ratios between explosions in dry and water-saturated rocks. Thus the amplitude reduction is sensitive to the extent of the damage zone as well as the pore water content.
Stora's fine notion of divergent amplitudes
Directory of Open Access Journals (Sweden)
Joseph C. Várilly
2016-11-01
Full Text Available Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.
Connected formulas for amplitudes in standard model
Energy Technology Data Exchange (ETDEWEB)
He, Song [CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Sciences,Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences,No. 19A Yuquan Road, Beijing 100049 (China); Zhang, Yong [Department of Physics, Beijing Normal University,Beijing 100875 (China); CAS Key Laboratory of Theoretical Physics,Institute of Theoretical Physics, Chinese Academy of Sciences,Beijing 100190 (China)
2017-03-17
Witten’s twistor string theory has led to new representations of S-matrix in massless QFT as a single object, including Cachazo-He-Yuan formulas in general and connected formulas in four dimensions. As a first step towards more realistic processes of the standard model, we extend the construction to QCD tree amplitudes with massless quarks and those with a Higgs boson. For both cases, we find connected formulas in four dimensions for all multiplicities which are very similar to the one for Yang-Mills amplitudes. The formula for quark-gluon color-ordered amplitudes differs from the pure-gluon case only by a Jacobian factor that depends on flavors and orderings of the quarks. In the formula for Higgs plus multi-parton amplitudes, the massive Higgs boson is effectively described by two additional massless legs which do not appear in the Parke-Taylor factor. The latter also represents the first twistor-string/connected formula for form factors.
Fatigue Reliability under Multiple-Amplitude Loads
DEFF Research Database (Denmark)
Talreja, R.
1979-01-01
for the initial tensile strength and the fatigue life, the probability distributions for the residual tensile strength in both the crack initiation and the crack propagation stages of fatigue are determined. The method is illustrated for two-amplitude loads by means of experimental results obtained by testing...
Ward identities for amplitudes with reggeized gluons
International Nuclear Information System (INIS)
Bartles, J.; Vacca, G.P.
2012-05-01
Starting from the effective action of high energy QCD we derive Ward identities for Green's functions of reggeized gluons. They follow from the gauge invariance of the effective action, and allow to derive new representations of amplitudes containing physical particles as well as reggeized gluons. We explicitly demonstrate their validity for the BFKL kernel, and we present a new derivation of the kernel.
Scattering amplitudes in super-renormalizable gravity
International Nuclear Information System (INIS)
Donà, Pietro; Giaccari, Stefano; Modesto, Leonardo; Rachwał, Lesław; Zhu, Yiwei
2015-01-01
We explicitly compute the tree-level on-shell four-graviton amplitudes in four, five and six dimensions for local and weakly nonlocal gravitational theories that are quadratic in both, the Ricci and scalar curvature with form factors of the d’Alembertian operator inserted between. More specifically we are interested in renormalizable, super-renormalizable or finite theories. The scattering amplitudes for these theories turn out to be the same as the ones of Einstein gravity regardless of the explicit form of the form factors. As a special case the four-graviton scattering amplitudes in Weyl conformal gravity are identically zero. Using a field redefinition, we prove that the outcome is correct for any number of external gravitons (on-shell n−point functions) and in any dimension for a large class of theories. However, when an operator quadratic in the Riemann tensor is added in any dimension (with the exception of the Gauss-Bonnet term in four dimensions) the result is completely altered, and the scattering amplitudes depend on all the form factors introduced in the action.
Constraints on low energy Compton scattering amplitudes
International Nuclear Information System (INIS)
Raszillier, I.
1979-04-01
We derive the constraints and correlations of fairly general type for Compton scattering amplitudes at energies below photoproduction threshold and fixed momentum transfer, following from (an upper bound on) the corresponding differential cross section above photoproduction threshold. The derivation involves the solution of an extremal problem in a certain space of vector - valued analytic functions. (author)
Analytic properties of many-particle amplitudes
Energy Technology Data Exchange (ETDEWEB)
Medvedev, B V; Pavlov, V P; Polivanov, M K; Sukhanov, A D [Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki; AN SSSR, Moscow. Matematicheskij Inst.)
1982-08-01
In the framework of N. N. Bogolyubov axiomatic approach the complete proof of the existence of an analytic function the boundary values of which are the amplitudes of any channel of n-particle process is given. The one-particle structure of this function is described.
International Nuclear Information System (INIS)
Petrovic, B.; Carelli, M. D.; Sandell, L.; Storrick, G. D.; Cavlina, N.
2008-01-01
Many emerging markets and smaller size countries are considering the nuclear option and the deployment of their first nuclear reactor(s). However, some of their requirements and available infrastructure are quite different from those of larger countries currently employing nuclear power. Specific considerations might include: a small size electrical grid, in some cases on the order of a few GWe; limited financial resources; no nuclear experience; inadequate availability of necessary material and people infrastructure. Large nuclear power plants of 1000 MWe or greater do not provide best fit. The IRIS (International Reactor Innovative and Secure) reactor, under development by an international team of eighteen organizations from nine countries led by Westinghouse specifically addresses these needs. IRIS is an advanced PWR with integral configuration that yields a simple design with enhanced safety. The IRIS size is 335 MWe and may be deployed in single or multiple modules. It can fit almost any grid, or a small utility within a larger grid; moreover, it allows incremental power additions as needed. The capital outlay is of the order of hundreds of millions rather than a few billions dollars. Successive construction and operation of multiple modules significantly reduces the required capital resources and capital at risk with generation income from earlier plants offsetting the construction outlays of subsequent ones. This is highly desirable in both developed and emerging markets, but it may be of critical importance to the latter. IRIS safety characteristics allow for licensing with a significantly reduced size of emergency zone, a critical feature for small countries and when cogeneration is desired. In fact, IRIS is designed to produce steam for district heating, water desalination and bio-fuel generation in addition to electricity. The U.S. Department of Energy (DOE) has announced in February 2008 its intention to contribute to funding the licensing of a 'Grid
Optimisation of amplitude distribution of magnetic Barkhausen noise
Pal'a, Jozef; Jančárik, Vladimír
2017-09-01
The magnetic Barkhausen noise (MBN) measurement method is a widely used non-destructive evaluation technique used for inspection of ferromagnetic materials. Besides other influences, the excitation yoke lift-off is a significant issue of this method deteriorating the measurement accuracy. In this paper, the lift-off effect is analysed mainly on grain oriented Fe-3%Si steel subjected to various heat treatment conditions. Based on investigation of relationship between the amplitude distribution of MBN and lift-off, an approach to suppress the lift-off effect is proposed. Proposed approach utilizes the digital feedback optimising the measurement based on the amplitude distribution of MBN. The results demonstrated that the approach can highly suppress the lift-off effect up to 2 mm.
Directory of Open Access Journals (Sweden)
Yu Gao
Full Text Available BACKGROUND: The human endogenous retroviral family W, Env(C7, member 1 gene (HERVWE1 is thought to participate in trophoblast cell fusion, and its expression is diminished in the placentas of singleton intrauterine growth-retarded pregnancies. However, there is limited information about the role of HERVWE1 in discordant fetal growth in twins. This study was to compare HERVWE1 gene expression between the placentas of discordant monozygotic twins and to identify its regulation by methylation. METHODOLOGY/PRINCIPAL FINDINGS: Fetuses from twenty-one pairs of monozygotic, dichorionic, discordant twins were marked as "smaller" or "larger" according to birth weight. Placental HERVWE1 mRNA and protein expression profiles were analyzed using quantitative RT-PCR and immunohistochemistry (IHC staining. Methylation profiles of the HERVWE1 promoter region were analyzed using a pyrosequencing assay. DNA methyltransferase (DNMT transcript levels were analyzed by RT-PCR. 5-methyl cytosine (5-MC was stained using an immunohistochemical assay. There was a significant negative correlation between HERVWE1 mRNA levels and birth weight in twins (P0.05. The DNMT3b3 mRNA levels in the smaller group were significantly downregulated compared with the larger group in discordant twins(P<0.05, whereas the DNMT3b7 mRNA levels in the smaller group were significantly upregulated compared with the larger group in discordant twins(P<0.05. CONCLUSIONS/SIGNIFICANCE: In discordant, monozygotic, dichorionic twins, HERVWE1 expression was higher in smaller fetuses and lower in larger fetuses. Methylation of the HERVWE1 gene promoter region may participate in the regulation of HERVWE1 gene expression in discordant twin pregnancies.
DETERMINISTIC COMPONENTS IN THE LIGHT CURVE AMPLITUDE OF Y OPH
International Nuclear Information System (INIS)
Pop, Alexandru; Turcu, Vlad; Vamos, Calin
2010-01-01
About two decades after the discovery of the amplitude decline of the light curve of the classical Cepheid Y Oph, its study is resumed using an increased amount of homogenized data and an extended time base. In our approach, the investigation of different time series concerning the light curve amplitude of Y Oph is not only the reason for the present study, but also a stimulus for developing a coherent methodology for studying long- and short-term variability phenomena in variable stars, taking into account the details of concrete observing conditions: amount of data, data sampling, time base, and individual errors of observational data. The statistical significance of this decreasing trend was estimated by assuming its linearity. We approached the decision-making process by formulating adequate null and alternative hypotheses, and testing the value of the regression line slope for different data sets via Monte Carlo simulations. A variability analysis, through various methods, of the original data and of the residuals obtained after removing the linear trend was performed. We also proposed a new statistical test, based on amplitude spectrum analysis and Monte Carlo simulations, intended to evaluate how detectible is a given (linear) trend in well-defined observing conditions: the trend detection probability. The main conclusion of our study on Y Oph is that, even if the false alarm probability is low enough to consider the decreasing trend to be statistically significant, the available data do not allow us to obtain a reasonably powerful test. We are able to confirm the light curve amplitude decline, and the order of magnitude of its slope with a better statistical substantiation. According to the obtained values of the trend detection probability, it seems that the trend we are dealing with is marked by a low detectibility. Our attempt to find signs of possible variability phenomena at shorter timescales ended by emphasizing the relative constancy of our data
Drouin, Héloïse; Davidson, Patrick S R
2015-12-01
It has previously been reported that priming a collectivistic social orientation (compared with an individualistic one) boosts object-location memory (Kühnen & Oyserman, 2002; Oyserman, Sorensen, Reber, & Chen, 2009). We conducted 4 experiments to replicate this reported effect, using the same methods as in those initial reports. In Experiment 1 (n = 145), we found a hint of a priming effect on object-location memory, but also an unanticipated interaction between priming and gender. In Experiment 2 (n = 90), we included gender as a formal factor and doubled the "dosage" of the priming, yet did not see any priming effects on memory. In Experiment 3 (n = 101), we octupled the priming "dosage" and again saw no significant effects on memory. Finally, in Experiment 4 (n = 102), we performed an exact replication of the methods of the original reports and again found no priming effects on memory. Any effects of this type of social orientation priming on object-location memory appear to be smaller and/or less robust than initially thought. (c) 2015 APA, all rights reserved).
Amplitude Modulation of Pulsation Modes in Delta Scuti Stars
Bowman, Dominic M.
2017-10-01
The pulsations in δ Sct stars are excited by a heat engine driving mechanism caused by increased opacity in their surface layers, and have pulsation periods of order a few hours. Space based observations in the last decade have revealed a diverse range of pulsational behaviour in these stars, which is investigated using an ensemble of 983 δ Sct stars observed continuously for 4 yr by the Kepler Space Telescope. A statistical search for amplitude modulation of pulsation modes is carried out and it is shown that 61.3 per cent of the 983 δ Sct stars exhibit significant amplitude modulation in at least a single pulsation mode, and that this is uncorrelated with effective temperature and surface gravity. Hence, the majority of δ Sct stars exhibit amplitude modulation, with time-scales of years and longer demonstrated to be significant in these stars both observationally and theoretically. An archetypal example of amplitude modulation in a δ Sct star is KIC 7106205, which contains only a single pulsation mode that varies significantly in amplitude whilst all other pulsation modes stay constant in amplitude and phase throughout the 4-yr Kepler data set. Therefore, the visible pulsational energy budget in this star, and many others, is not conserved over 4 yr. Models of beating of close-frequency pulsation modes are used to identify δ Sct stars with frequencies that lie closer than 0.001 d^{-1}, which are barely resolved using 4 yr of Kepler observations, and maintain their independent identities over 4 yr. Mode coupling models are used to quantify the strength of coupling and distinguish between non-linearity in the form of combination frequencies and non-linearity in the form of resonant mode coupling for families of pulsation modes in several stars. The changes in stellar structure caused by stellar evolution are investigated for two high amplitude δ Sct (HADS) stars in the Kepler data set, revealing a positive quadratic change in phase for the fundamental and
DEFF Research Database (Denmark)
Sonne, Jesper; Martín González, Ana M.; Maruyama, Pietro K.
2016-01-01
Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographicall...
Veer, I.M.; Oei, N.Y.L.; van Buchem, M.A.; Spinhoven, Ph.; Elzinga, B.M.; Rombouts, S.A.R.B.
2015-01-01
Hippocampus and amygdala volumes in posttraumatic stress disorder (PTSD) related to childhood trauma are relatively understudied, albeit the potential importance to the disorder. Whereas some studies reported smaller hippocampal volumes, little evidence was found for abnormal amygdala volumes. Here
Cascaded Amplitude Modulations in Sound Texture Perception
DEFF Research Database (Denmark)
McWalter, Richard Ian; Dau, Torsten
2017-01-01
. In this study, we investigated the perception of sound textures that contain rhythmic structure, specifically second-order amplitude modulations that arise from the interaction of different modulation rates, previously described as "beating" in the envelope-frequency domain. We developed an auditory texture...... model that utilizes a cascade of modulation filterbanks that capture the structure of simple rhythmic patterns. The model was examined in a series of psychophysical listening experiments using synthetic sound textures-stimuli generated using time-averaged statistics measured from real-world textures....... In a texture identification task, our results indicated that second-order amplitude modulation sensitivity enhanced recognition. Next, we examined the contribution of the second-order modulation analysis in a preference task, where the proposed auditory texture model was preferred over a range of model...
Source amplitudes for active exterior cloaking
International Nuclear Information System (INIS)
Norris, Andrew N; Amirkulova, Feruza A; Parnell, William J
2012-01-01
The active cloak comprises a discrete set of multipole sources that destructively interfere with an incident time harmonic scalar wave to produce zero total field over a finite spatial region. For a given number of sources and their positions in two dimensions it is shown that the multipole amplitudes can be expressed as infinite sums of the coefficients of the incident wave decomposed into regular Bessel functions. The field generated by the active sources vanishes in the infinite region exterior to a set of circles defined by the relative positions of the sources. The results provide a direct solution to the inverse problem of determining the source amplitudes. They also define a broad class of non-radiating discrete sources. (paper)
Constructing QCD one-loop amplitudes
International Nuclear Information System (INIS)
Forde, D
2008-01-01
In the context of constructing one-loop amplitudes using a unitarity bootstrap approach we discuss a general systematic procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted after examining the behavior of the cut integrand as the unconstrained parameters of a specifically chosen parameterization of the cut loop momentum approach infinity. Measurements of new physics at the forthcoming experimental program at CERN's Large Hadron Collider (LHC) will require a precise understanding of processes at next-to-leading order (NLO). This places increased demands for the computation of new one-loop amplitudes. This in turn has spurred recent developments towards improved calculational techniques. Direct calculations using Feynman diagrams are in general inefficient. Developments of more efficient techniques have usually centered around unitarity techniques [1], where tree amplitudes are effectively 'glued' together to form loops. The most straightforward application of this method, in which the cut loop momentum is in D = 4, allows for the computation of 'cut-constructible' terms only, i.e. (poly)logarithmic containing terms and any related constants. QCD amplitudes contain, in addition to such terms, rational pieces which cannot be derived using such cuts. These 'missing' rational parts can be extracted using cut loop momenta in D = 4-2 (var e psilon). The greater difficulty of such calculations has restricted the application of this approach, although recent developments [3, 4] have provided new promise for this technique. Recently the application of on-shell recursion relations [5] to obtaining the 'missing' rational parts of one-loop processes [6] has provided an alternative very promising solution to this problem. In combination with unitarity methods an 'on-shell bootstrap' approach provides an efficient technique for computing complete one-loop QCD amplitudes [7]. Additionally
Differential equations, associators, and recurrences for amplitudes
Directory of Open Access Journals (Sweden)
Georg Puhlfürst
2016-01-01
Full Text Available We provide new methods to straightforwardly obtain compact and analytic expressions for ϵ-expansions of functions appearing in both field and string theory amplitudes. An algebraic method is presented to explicitly solve for recurrence relations connecting different ϵ-orders of a power series solution in ϵ of a differential equation. This strategy generalizes the usual iteration by Picard's method. Our tools are demonstrated for generalized hypergeometric functions. Furthermore, we match the ϵ-expansion of specific generalized hypergeometric functions with the underlying Drinfeld associator with proper Lie algebra and monodromy representations. We also apply our tools for computing ϵ-expansions for solutions to generic first-order Fuchsian equations (Schlesinger system. Finally, we set up our methods to systematically get compact and explicit α′-expansions of tree-level superstring amplitudes to any order in α′.
Unitarity and amplitudes for high energies
International Nuclear Information System (INIS)
Efimov, G.V.
1997-01-01
It is shown that in the quantum field theory of scalar particles with mass m the following inequalities for the upper bound for the amplitude of elastic scattering Μ(s,t) |Μ(s,t)| 0 )s, (|t|≥|t 0 |>0) and for the total cross section of scalar particles σ tot (s)≤C|d/dt ln Im Μ(s,t)| t=0 , (s → ∞) are valid. This result is based on the unitarity of the S-matrix on the mass shell and on a natural assumption that the imaginary part of the elastic scattering Im Μ(s,t) is a differentiable and convex down function in some vicinity of t=0. The locality of the theory and the analyticity of the elastic amplitude in the Martin-Lehmann ellipse are not used in proving these inequalities
Large amplitude waves and fields in plasmas
International Nuclear Information System (INIS)
Angelis, U. de; Naples Univ.
1990-02-01
In this review, based mostly on the results of the recent workshop on ''Large Amplitude Waves and Fields in Plasmas'' held at ICTP (Trieste, Italy) in May 1989 during the Spring College on Plasma Physics, I will mostly concentrate on underdense, cold, homogeneous plasmas, discussing some of the alternative (to fusion) uses of laser-plasma interaction. In Part I an outline of some basic non-linear processes is given, together with some recent experimental results. The processes are chosen because of their relevance to the applications or because new interesting developments have been reported at the ICTP workshop (or both). In Part II the excitation mechanisms and uses of large amplitude plasma waves are presented: these include phase-conjugation in plasmas, plasma based accelerators (beat-wave, plasma wake-field and laser wake-field), plasma lenses and plasma wigglers for Free Electron Lasers. (author)
Integrable spin chains and scattering amplitudes
Energy Technology Data Exchange (ETDEWEB)
Bartels, J.; Prygarin, A. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Lipatov, L.N. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Petersburg Nuclear Physics Institute (Russian Federation); Sankt-Peterburgskij Univ., St. Petersburg (Russian Federation)
2011-04-15
In this review we show that the multi-particle scattering amplitudes in N=4 SYM at large N{sub c} and in the multi-Regge kinematics for some physical regions have the high energy behavior appearing from the contribution of the Mandelstam cuts in the complex angular momentum plane of the corresponding t-channel partial waves. These Mandelstam cuts or Regge cuts are resulting from gluon composite states in the adjoint representation of the gauge group SU(N{sub c}). In the leading logarithmic approximation (LLA) their contribution to the six point amplitude is in full agreement with the known two-loop result. The Hamiltonian for the Mandelstam states constructed from n gluons in LLA coincides with the local Hamiltonian of an integrable open spin chain. We construct the corresponding wave functions using the integrals of motion and the Baxter-Sklyanin approach. (orig.)
Understanding the amplitudes of noise correlation measurements
Tsai, Victor C.
2011-01-01
Cross correlation of ambient seismic noise is known to result in time series from which station-station travel-time measurements can be made. Part of the reason that these cross-correlation travel-time measurements are reliable is that there exists a theoretical framework that quantifies how these travel times depend on the features of the ambient noise. However, corresponding theoretical results do not currently exist to describe how the amplitudes of the cross correlation depend on such features. For example, currently it is not possible to take a given distribution of noise sources and calculate the cross correlation amplitudes one would expect from such a distribution. Here, we provide a ray-theoretical framework for calculating cross correlations. This framework differs from previous work in that it explicitly accounts for attenuation as well as the spatial distribution of sources and therefore can address the issue of quantifying amplitudes in noise correlation measurements. After introducing the general framework, we apply it to two specific problems. First, we show that we can quantify the amplitudes of coherency measurements, and find that the decay of coherency with station-station spacing depends crucially on the distribution of noise sources. We suggest that researchers interested in performing attenuation measurements from noise coherency should first determine how the dominant sources of noise are distributed. Second, we show that we can quantify the signal-to-noise ratio of noise correlations more precisely than previous work, and that these signal-to-noise ratios can be estimated for given situations prior to the deployment of seismometers. It is expected that there are applications of the theoretical framework beyond the two specific cases considered, but these applications await future work.
On the infinities of closed superstring amplitudes
International Nuclear Information System (INIS)
Restuccia, A.; Taylor, J.G.
1988-01-01
The authors present an analysis of possible infinities that may be present in uncompactified multi-loop heterotic and type II superstring amplitudes constructed, without use of the short-string limit, in the light-cone gauge, and with use of a closed [10]-SUSY field theory algebra. Various types of degenerations of the integrand are discussed on the string worldsheet. No infinities are found, modulo (for type II) a particular identity for Green's functions
Deep Inelastic Scattering at the Amplitude Level
International Nuclear Information System (INIS)
Brodsky, Stanley J.
2005-01-01
The deep inelastic lepton scattering and deeply virtual Compton scattering cross sections can be interpreted in terms of the fundamental wavefunctions defined by the light-front Fock expansion, thus allowing tests of QCD at the amplitude level. The AdS/CFT correspondence between gauge theory and string theory provides remarkable new insights into QCD, including a model for hadronic wavefunctions which display conformal scaling at short distances and color confinement at large distances
Multichannel conformal blocks for scattering amplitudes
Belitsky, A. V.
2018-05-01
By performing resummation of small fermion-antifermion pairs within the pentagon form factor program to scattering amplitudes in planar N = 4 superYang-Mills theory, we construct multichannel conformal blocks within the flux-tube picture for N-sided NMHV polygons. This procedure is equivalent to summation of descendants of conformal primaries in the OPE framework. The resulting conformal partial waves are determined by multivariable hypergeometric series of Lauricella-Saran type.
How to calculate the Coulomb scattering amplitude
International Nuclear Information System (INIS)
Grosse, H.; Narnhofer, H.; Thirring, W.
1974-01-01
The derivation of scattering amplitudes for Coulomb scattering is discussed. A derivation of the S-matrix elements for a dense set of states in momentum space is given in the framework of time dependent scattering theory. The convergence of the S-matrix is studied. A purely algebraic derivation of the S-matrix elements and phase shifts is also presented. (HFdV)
Scattering amplitudes from multivariate polynomial division
Energy Technology Data Exchange (ETDEWEB)
Mastrolia, Pierpaolo, E-mail: pierpaolo.mastrolia@cern.ch [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Dipartimento di Fisica e Astronomia, Universita di Padova, Padova (Italy); INFN Sezione di Padova, via Marzolo 8, 35131 Padova (Italy); Mirabella, Edoardo, E-mail: mirabell@mppmu.mpg.de [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Ossola, Giovanni, E-mail: GOssola@citytech.cuny.edu [New York City College of Technology, City University of New York, 300 Jay Street, Brooklyn, NY 11201 (United States); Graduate School and University Center, City University of New York, 365 Fifth Avenue, New York, NY 10016 (United States); Peraro, Tiziano, E-mail: peraro@mppmu.mpg.de [Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany)
2012-11-15
We show that the evaluation of scattering amplitudes can be formulated as a problem of multivariate polynomial division, with the components of the integration-momenta as indeterminates. We present a recurrence relation which, independently of the number of loops, leads to the multi-particle pole decomposition of the integrands of the scattering amplitudes. The recursive algorithm is based on the weak Nullstellensatz theorem and on the division modulo the Groebner basis associated to all possible multi-particle cuts. We apply it to dimensionally regulated one-loop amplitudes, recovering the well-known integrand-decomposition formula. Finally, we focus on the maximum-cut, defined as a system of on-shell conditions constraining the components of all the integration-momenta. By means of the Finiteness Theorem and of the Shape Lemma, we prove that the residue at the maximum-cut is parametrized by a number of coefficients equal to the number of solutions of the cut itself.
Cascaded Amplitude Modulations in Sound Texture Perception
Directory of Open Access Journals (Sweden)
Richard McWalter
2017-09-01
Full Text Available Sound textures, such as crackling fire or chirping crickets, represent a broad class of sounds defined by their homogeneous temporal structure. It has been suggested that the perception of texture is mediated by time-averaged summary statistics measured from early auditory representations. In this study, we investigated the perception of sound textures that contain rhythmic structure, specifically second-order amplitude modulations that arise from the interaction of different modulation rates, previously described as “beating” in the envelope-frequency domain. We developed an auditory texture model that utilizes a cascade of modulation filterbanks that capture the structure of simple rhythmic patterns. The model was examined in a series of psychophysical listening experiments using synthetic sound textures—stimuli generated using time-averaged statistics measured from real-world textures. In a texture identification task, our results indicated that second-order amplitude modulation sensitivity enhanced recognition. Next, we examined the contribution of the second-order modulation analysis in a preference task, where the proposed auditory texture model was preferred over a range of model deviants that lacked second-order modulation rate sensitivity. Lastly, the discriminability of textures that included second-order amplitude modulations appeared to be perceived using a time-averaging process. Overall, our results demonstrate that the inclusion of second-order modulation analysis generates improvements in the perceived quality of synthetic textures compared to the first-order modulation analysis considered in previous approaches.
Transversity Amplitudes in Hypercharge Exchange Processes
International Nuclear Information System (INIS)
Aguilar Benitez de Lugo, M.
1979-01-01
' In this work we present several techniques developed for the extraction of the. Transversity amplitudes governing quasi two-body meson baryon reactions with hypercharge exchange. We review the methods used in processes having a pure spin configuration, as well as the more relevant results obtained with data from K p and Tp interactions at intermediate energies. The predictions of the additive quark model and the ones following from exchange degeneracy and etoxicity are discussed. We present a formalism for amplitude analysis developed for reactions with mixed spin configurations and discuss the methods of parametric estimation of the moduli and phases of the amplitudes, as well as the various tests employed to check the goodness of the fits. The calculation of the generalized joint density matrices is given and we propose a method based on the generalization of the idea of multipole moments, which allows to investigate the structure of the decay angular correlations and establishes the quality of the fits and the validity of the simplifying assumptions currently used in this type of studies. (Author) 43 refs
Charmless B{sub (s)} → VV decays in factorization-assisted topological-amplitude approach
Energy Technology Data Exchange (ETDEWEB)
Wang, Chao; Zhang, Qi-An [CAS, Institute of High Energy Physics, P.O. Box 918, Beijing (China); University of Chinese Academy of Sciences, School of Physics, Beijing (China); Li, Ying [Yantai University, Department of Physics, Yantai (China); CAS, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China); Lue, Cai-Dian [CAS, Institute of High Energy Physics, P.O. Box 918, Beijing (China); University of Chinese Academy of Sciences, School of Physics, Beijing (China); CAS, State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)
2017-05-15
Within the factorization-assisted topological-amplitude approach, we studied the 33 charmless B{sub (s)} → VV decays, where V stands for a light vector meson. According to the flavor flows, the amplitude of each process can be decomposed into eight different topologies. In contrast to the conventional flavor diagrammatic approach, we further factorize each topological amplitude into decay constant, form factors and unknown universal parameters. By χ{sup 2} fitting 46 experimental observables, we extracted 10 theoretical parameters with χ{sup 2} per degree of freedom around 2. Using the fitted parameters, we calculated the branching fractions, polarization fractions, CP asymmetries and relative phases between polarization amplitudes of each decay mode. The decay channels dominated by tree diagram have large branching fractions and large longitudinal polarization fraction. The branching fractions and longitudinal polarization fractions of color-suppressed decays become smaller. Current experimental data of large transverse polarization fractions in the penguin dominant decay channels can be explained by only one transverse amplitude of penguin annihilation diagram. Our predictions of the not yet measured channels can be tested in the ongoing LHCb experiment and the Belle-II experiment in the future. (orig.)
A General Method to Estimate Earthquake Moment and Magnitude using Regional Phase Amplitudes
Energy Technology Data Exchange (ETDEWEB)
Pasyanos, M E
2009-11-19
This paper presents a general method of estimating earthquake magnitude using regional phase amplitudes, called regional M{sub o} or regional M{sub w}. Conceptually, this method uses an earthquake source model along with an attenuation model and geometrical spreading which accounts for the propagation to utilize regional phase amplitudes of any phase and frequency. Amplitudes are corrected to yield a source term from which one can estimate the seismic moment. Moment magnitudes can then be reliably determined with sets of observed phase amplitudes rather than predetermined ones, and afterwards averaged to robustly determine this parameter. We first examine in detail several events to demonstrate the methodology. We then look at various ensembles of phases and frequencies, and compare results to existing regional methods. We find regional M{sub o} to be a stable estimator of earthquake size that has several advantages over other methods. Because of its versatility, it is applicable to many more events, particularly smaller events. We make moment estimates for earthquakes ranging from magnitude 2 to as large as 7. Even with diverse input amplitude sources, we find magnitude estimates to be more robust than typical magnitudes and existing regional methods and might be tuned further to improve upon them. The method yields a more meaningful quantity of seismic moment, which can be recast as M{sub w}. Lastly, it is applied here to the Middle East region using an existing calibration model, but it would be easy to transport to any region with suitable attenuation calibration.
Modeling Small-Amplitude Perturbations in Inertial Confinement Fusion Pellets
Zalesak, Steven; Metzler, N.; Velikovich, A. L.; Gardner, J. H.; Manheimer, W.
2005-10-01
Recent advances in inertial confinement fusion (ICF) technology serve to ensure that imploding laser-driven ICF pellets will spend a significantly larger portion of their time in what is regarded as the ``linear'' portion of their perturbation evolution, i.e., in the presence of small-amplitude but nonetheless evolving perturbations. Since the evolution of these linear perturbations collectively form the initial conditions for the subsequent nonlinear evolution of the pellet, which in turn determines the energy yield of the pellet, the accurate numerical modeling of these small-amplitude perturbations has taken on an increased importance. This modeling is difficult despite the expected linear evolution of the perturbations themselves, because these perturbations are embedded in a highly nonlinear, strongly-shocked, and highly complex flow field which in and of itself stresses numerical computation capabilities, and whose simulation often employs numerical techniques which were not designed with the proper treatment of small-amplitude perturbations in mind. In this paper we will review some of the techniques that we have recently found to be of use toward this end.
Interpretation of second Born amplitudes in electron capture
International Nuclear Information System (INIS)
McGuire, J.H.; Simony, P.R.; Weaver, O.L.; Macek, J.
1982-01-01
Exact sound Born amplitudes for 1s-1s electron capture are presented and interpreted in terms of contributions from intermediate states off the energy shell and on the energy shell. The classical model of Thomas corresponds to two-step scattering via one particular on-shell intermediate state. In the high-velocity limit for 1s-1s capture, this on-shell intermediate state of the Thomas model accounts for one-half of the total cross section, i.e., the second Born cross section. The other half comes from off-energy-shell intermediate states near the on-shell Thomas state. Above 5 MeV both the off-shell and on-shell amplitudes have a simple structure near the Thomas peak. Below 1 MeV, contributions from a broader range of intermediate states are evident in the amplitudes. Although the contribution from the Thomas state is not large below 1 MeV, other second Born effects are significant
Interferometric Imaging Directly with Closure Phases and Closure Amplitudes
Chael, Andrew A.; Johnson, Michael D.; Bouman, Katherine L.; Blackburn, Lindy L.; Akiyama, Kazunori; Narayan, Ramesh
2018-04-01
Interferometric imaging now achieves angular resolutions as fine as ∼10 μas, probing scales that are inaccessible to single telescopes. Traditional synthesis imaging methods require calibrated visibilities; however, interferometric calibration is challenging, especially at high frequencies. Nevertheless, most studies present only a single image of their data after a process of “self-calibration,” an iterative procedure where the initial image and calibration assumptions can significantly influence the final image. We present a method for efficient interferometric imaging directly using only closure amplitudes and closure phases, which are immune to station-based calibration errors. Closure-only imaging provides results that are as noncommittal as possible and allows for reconstructing an image independently from separate amplitude and phase self-calibration. While closure-only imaging eliminates some image information (e.g., the total image flux density and the image centroid), this information can be recovered through a small number of additional constraints. We demonstrate that closure-only imaging can produce high-fidelity results, even for sparse arrays such as the Event Horizon Telescope, and that the resulting images are independent of the level of systematic amplitude error. We apply closure imaging to VLBA and ALMA data and show that it is capable of matching or exceeding the performance of traditional self-calibration and CLEAN for these data sets.
Spectator scattering at NLO in non-leptonic B decays: Leading penguin amplitudes
International Nuclear Information System (INIS)
Beneke, M.; Jaeger, S.
2007-01-01
We complete the computation of the 1-loop (α s 2 ) corrections to hard spectator scattering in non-leptonic B decays at leading power in Λ/m b by evaluating the penguin amplitudes. This extends the knowledge of these next-to-next-to-leading-order contributions in the QCD factorization formula for B decays to a much wider class of final states, including all pseudoscalar-pseudoscalar, pseudoscalar-vector, and longitudinally polarized vector-vector final states, except final states with η or η ' mesons. The new 1-loop correction is significant for the colour-suppressed amplitudes, but turns out to be strongly suppressed for the leading QCD penguin amplitude α 4 p . We provide numerical values of the phenomenological P/T and C/T amplitude ratios for the ππ, πρ and ρρ final states, and discuss corrections to several relations between electroweak penguin and tree amplitudes
One-loop triple collinear splitting amplitudes in QCD
Energy Technology Data Exchange (ETDEWEB)
Badger, Simon; Buciuni, Francesco; Peraro, Tiziano [Higgs Centre for Theoretical Physics, School of Physics and Astronomy, University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom)
2015-09-28
We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic Higgs plus four partons amplitudes. We present compact results for primitive helicity splitting amplitudes making use of super-symmetric decompositions. The universality of the collinear factorisation is checked numerically against the full colour six parton squared matrix elements.
Measurement of smaller colon polyp in CT colonography images using morphological image processing.
Manjunath, K N; Siddalingaswamy, P C; Prabhu, G K
2017-11-01
Automated measurement of the size and shape of colon polyps is one of the challenges in Computed tomography colonography (CTC). The objective of this retrospective study was to improve the sensitivity and specificity of smaller polyp measurement in CTC using image processing techniques. A domain knowledge-based method has been implemented with hybrid method of colon segmentation, morphological image processing operators for detecting the colonic structures, and the decision-making system for delineating the smaller polyp-based on a priori knowledge. The method was applied on 45 CTC dataset. The key finding was that the smaller polyps were accurately measured. In addition to 6-9 mm range, polyps of even processing. It takes [Formula: see text] min for measuring the smaller polyp in a dataset of 500 CTC images. With this method, [Formula: see text] and [Formula: see text] were achieved. The domain-based approach with morphological image processing has given good results. The smaller polyps were measured accurately which helps in making right clinical decisions. Qualitatively and quantitatively the results were acceptable when compared to the ground truth at [Formula: see text].
Yang, Liping; Zhang, Lei; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Wang, Xin; Wang, Linghua
2018-03-01
Multi-order structure functions in the solar wind are reported to display a monofractal scaling when sampled parallel to the local magnetic field and a multifractal scaling when measured perpendicularly. Whether and to what extent will the scaling anisotropy be weakened by the enhancement of turbulence amplitude relative to the background magnetic strength? In this study, based on two runs of the magnetohydrodynamic (MHD) turbulence simulation with different relative levels of turbulence amplitude, we investigate and compare the scaling of multi-order magnetic structure functions and magnetic probability distribution functions (PDFs) as well as their dependence on the direction of the local field. The numerical results show that for the case of large-amplitude MHD turbulence, the multi-order structure functions display a multifractal scaling at all angles to the local magnetic field, with PDFs deviating significantly from the Gaussian distribution and a flatness larger than 3 at all angles. In contrast, for the case of small-amplitude MHD turbulence, the multi-order structure functions and PDFs have different features in the quasi-parallel and quasi-perpendicular directions: a monofractal scaling and Gaussian-like distribution in the former, and a conversion of a monofractal scaling and Gaussian-like distribution into a multifractal scaling and non-Gaussian tail distribution in the latter. These results hint that when intermittencies are abundant and intense, the multifractal scaling in the structure functions can appear even if it is in the quasi-parallel direction; otherwise, the monofractal scaling in the structure functions remains even if it is in the quasi-perpendicular direction.
Fewer but not smaller schools in declining fish and krill populations.
Brierley, Andrew S; Cox, Martin J
2015-01-05
Many pelagic species (species that live in the water column), including herring and krill, aggregate to form schools, shoals, or swarms (hereafter simply "schools," although the words are not synonyms). Schools provide benefits to individual members, including locomotory economy and protection from predators that prey on individuals, but paradoxically make schooling species energetically viable and commercially attractive targets for predators of groups and for fishers. Large schools are easier to find and yield greater prey/catch than small schools, and there is a requirement from fields as diverse as theoretical ecology and fisheries management to understand whether and how aggregation sizes change with changing population size. We collated data from vertical echosounder surveys of taxonomically diverse pelagic stocks from geographically diverse ecosystems. The data contain common significant positive linear stock-biomass to school-number relationships. They show that the numbers of schools in the stocks change with changing stock biomass and suggest that the distributions of school sizes do not change with stock biomass. New data that we collected using a multibeam sonar, which can image entire schools, contained the same stock-biomass to school-number relationship and confirm that the distribution of school sizes is not related to changing stock size: put simply, as stocks decline, individuals are distributed among fewer schools, not smaller schools. Since school characteristics affect catchability (the ease or difficulty with which fishers can capture target species) and availability of prey to predators, our findings have commercial and ecological implications, particularly within the aspirational framework of ecosystem-based management of marine systems. Copyright © 2015 Elsevier Ltd. All rights reserved.
Bilateral preictal signature of phase-amplitude coupling in canine epilepsy.
Gagliano, Laura; Bou Assi, Elie; Nguyen, Dang K; Rihana, Sandy; Sawan, Mohamad
2018-01-01
Seizure forecasting would improve the quality of life of patients with refractory epilepsy. Although early findings were optimistic, no single feature has been found capable of individually characterizing brain dynamics during transition to seizure. Cross-frequency phase amplitude coupling has been recently proposed as a precursor of seizure activity. This work evaluates the existence of a statistically significant difference in mean phase amplitude coupling distribution between the preictal and interictal states of seizures in dogs with bilaterally implanted intracranial electrodes. Results show a statistically significant change (p<0.05) of phase amplitude coupling during the preictal phase. This change is correlated with the position of implanted electrodes and is more significant within high-gamma frequency bands. These findings highlight the potential benefit of bilateral iEEG analysis and the feasibility of seizure forecasting based on slow modulation of high frequency amplitude. Copyright © 2017 Elsevier B.V. All rights reserved.
Loop amplitudes in an extended gravity theory
Dunbar, David C.; Godwin, John H.; Jehu, Guy R.; Perkins, Warren B.
2018-05-01
We extend the S-matrix of gravity by the addition of the minimal three-point amplitude or equivalently adding R3 terms to the Lagrangian. We demonstrate how Unitarity can be used to simply examine the renormalisability of this theory and determine the R4 counter-terms that arise at one-loop. We find that the combination of R4 terms that arise in the extended theory is complementary to the R4 counter-term associated with supersymmetric Lagrangians.
Loop-quantum-gravity vertex amplitude.
Engle, Jonathan; Pereira, Roberto; Rovelli, Carlo
2007-10-19
Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity.
Speech production in amplitude-modulated noise
DEFF Research Database (Denmark)
Macdonald, Ewen N; Raufer, Stefan
2013-01-01
The Lombard effect refers to the phenomenon where talkers automatically increase their level of speech in a noisy environment. While many studies have characterized how the Lombard effect influences different measures of speech production (e.g., F0, spectral tilt, etc.), few have investigated...... the consequences of temporally fluctuating noise. In the present study, 20 talkers produced speech in a variety of noise conditions, including both steady-state and amplitude-modulated white noise. While listening to noise over headphones, talkers produced randomly generated five word sentences. Similar...... of noisy environments and will alter their speech accordingly....
Optical twists in phase and amplitude
DEFF Research Database (Denmark)
Daria, Vincent R.; Palima, Darwin; Glückstad, Jesper
2011-01-01
where both phase and amplitude express a helical profile as the beam propagates in free space. Such a beam can be accurately referred to as an optical twister. We characterize optical twisters and demonstrate their capacity to induce spiral motion on particles trapped along the twisters’ path. Unlike LG...... beams, the far field projection of the twisted optical beam maintains a high photon concentration even at higher values of topological charge. Optical twisters have therefore profound applications to fundamental studies of light and atoms such as in quantum entanglement of the OAM, toroidal traps...
First order correction to quasiclassical scattering amplitude
International Nuclear Information System (INIS)
Kuz'menko, A.V.
1978-01-01
First order (with respect to h) correction to quasiclassical with the aid of scattering amplitude in nonrelativistic quantum mechanics is considered. This correction is represented by two-loop diagrams and includes the double integrals. With the aid of classical equations of motion, the sum of the contributions of the two-loop diagrams is transformed into the expression which includes one-dimensional integrals only. The specific property of the expression obtained is that the integrand does not possess any singularities in the focal points of the classical trajectory. The general formula takes much simpler form in the case of one-dimensional systems
Tomography for amplitudes of hard exclusive processes
International Nuclear Information System (INIS)
Polyakov, M.V.
2008-01-01
We discuss which part of information about hadron structure encoded in the Generalized Parton Distributions (GPDs) [part of total GPD image] can be restored from the known amplitude of a hard exclusive process. The physics content of this partial image is analyzed. Among other things, we show that this partial image contains direct information about how the target hadron responses to the (string) quark-antiquark operator of arbitrary spin J. Explicit equations relating physics content of the partial image of GPDs directly to the data are derived. Also some new results concerning the dual parametrization of GPDs are presented
Inverse amplitude method and Adler zeros
International Nuclear Information System (INIS)
Gomez Nicola, A.; Pelaez, J. R.; Rios, G.
2008-01-01
The inverse amplitude method is a powerful unitarization technique to enlarge the energy applicability region of effective Lagrangians. It has been widely used to describe resonances in hadronic physics, combined with chiral perturbation theory, as well as in the strongly interacting symmetry breaking sector. In this work we show how it can be slightly modified to also account for the subthreshold region, incorporating correctly the Adler zeros required by chiral symmetry and eliminating spurious poles. These improvements produce negligible effects on the physical region.
Survey of vibration amplitudes throughout the linac
International Nuclear Information System (INIS)
Werner, K.L.
1984-01-01
The magnitude of vibrations of the Linac structure due to on site disturbances, such as cooling towers, pumps, generators, Highway 280 overpass traffic, is of interest. CN-263, for example, discusses tolerances of random (i.e., uncorrelated) quad jitter and suggests that amplitudes should not exceed 0.7 microns rms. This note describes the results of a series of measurements carried out in the summer of 1983. In general, the tolerance is not exceeded, but there appears not to be a good safety factor at low frequencies
Ludwig, Kip A.; Langhals, Nicholas B.; Joseph, Mike D.; Richardson-Burns, Sarah M.; Hendricks, Jeffrey L.; Kipke, Daryl R.
2011-02-01
We investigated using poly(3,4-ethylenedioxythiophene) (PEDOT) to lower the impedance of small, gold recording electrodes with initial impedances outside of the effective recording range. Smaller electrode sites enable more densely packed arrays, increasing the number of input and output channels to and from the brain. Moreover, smaller electrode sizes promote smaller probe designs; decreasing the dimensions of the implanted probe has been demonstrated to decrease the inherent immune response, a known contributor to the failure of long-term implants. As expected, chronically implanted control electrodes were unable to record well-isolated unit activity, primarily as a result of a dramatically increased noise floor. Conversely, electrodes coated with PEDOT consistently recorded high-quality neural activity, and exhibited a much lower noise floor than controls. These results demonstrate that PEDOT coatings enable electrode designs 15 µm in diameter.
Energy Technology Data Exchange (ETDEWEB)
Lorentzen, P. (IPL Ingenieurbuero Peter Lorentzen, Frankfurt am Main (Germany))
1999-06-01
The trend to size is escalating into gigantism. The biggest in the branch merge to become the oversized. In view of this situation, the question which arises is what are the survival chances of the smaller players Will they all drop out of the running The answer to this question does not only concern the future order books of smaller companies, but in conjunction therewith and predominately the social security of employees, type and scope of assignments as well as the competitive situation and the consequences of all these on remuneration. (orig.)
Wang, Zilian; Luo, Yanmin; Sun, Hongyu; Zhou, Yi; Huang, Linhuan; Li, Manchao; Fang, Qun; Jiang, Shiwen
2012-01-01
Background The human endogenous retroviral family W, Env(C7), member 1 gene (HERVWE1) is thought to participate in trophoblast cell fusion, and its expression is diminished in the placentas of singleton intrauterine growth-retarded pregnancies. However, there is limited information about the role of HERVWE1 in discordant fetal growth in twins. This study was to compare HERVWE1 gene expression between the placentas of discordant monozygotic twins and to identify its regulation by methylation. Methodology/Principal Findings Fetuses from twenty-one pairs of monozygotic, dichorionic, discordant twins were marked as “smaller” or “larger” according to birth weight. Placental HERVWE1 mRNA and protein expression profiles were analyzed using quantitative RT-PCR and immunohistochemistry (IHC) staining. Methylation profiles of the HERVWE1 promoter region were analyzed using a pyrosequencing assay. DNA methyltransferase (DNMT) transcript levels were analyzed by RT-PCR. 5-methyl cytosine (5-MC) was stained using an immunohistochemical assay. There was a significant negative correlation between HERVWE1 mRNA levels and birth weight in twins (P0.05). The DNMT3b3 mRNA levels in the smaller group were significantly downregulated compared with the larger group in discordant twins(P<0.05), whereas the DNMT3b7 mRNA levels in the smaller group were significantly upregulated compared with the larger group in discordant twins(P<0.05). Conclusions/Significance In discordant, monozygotic, dichorionic twins, HERVWE1 expression was higher in smaller fetuses and lower in larger fetuses. Methylation of the HERVWE1 gene promoter region may participate in the regulation of HERVWE1 gene expression in discordant twin pregnancies. PMID:22457770
Directory of Open Access Journals (Sweden)
Parag Suresh Mahajan
2015-01-01
Full Text Available Purpose. To test if diameter of normal anterior cruciate ligament (ACL can be measured by ultrasound (US, to see if there is a relationship between smaller ACL diameter and ACL injury, and to assess agreement between radiologists in measuring ACL diameter in cases and matched controls. Materials and Methods. In this ethics committee-approved study, maximum diameter of ACL near tibial insertion site was measured by static and dynamic US study in 25 normal contralateral knees of subjects who suffered noncontact ACL injury and in 25 matched control subjects. Results. ACL was visualized as a thick linear hypoechoic band inserted approximately 11 mm caudal to the tibial plateau and the intercondylar eminence. Maximum diameter of contralateral ACL near tibial insertion site among injured subjects was significantly smaller than in noninjured subjects (0.62 ± 0.07 cm versus 0.81 ± 0.06 cm; P<0.0001. In the regression analysis, the diameter of ACL near tibial insertion site was found significantly proportional to body weight and not significantly associated to height, gender, and age. Conclusion. Diameter of normal ACL near tibial insertion site can be measured by US and the maximum diameter is significantly smaller among subjects with noncontact ACL injury. US is a promising modality that can be used as an excellent screening test to detect subjects especially aspiring athletes prone to ACL injury. Very strong agreement was observed between radiologists in measuring ACL diameter.
Multichannel amplitude analyser for nuclear spectrometry
International Nuclear Information System (INIS)
Jankovic, S.; Milovanovic, B.
2003-01-01
A multichannel amplitude analyser with 4096 channels was designed. It is based on a fast 12-bit analog-to-digital converter. The intended purpose of the instrument is recording nuclear spectra by means of scintillation detectors. The computer link is established through an opto-isolated serial connection cable, thus reducing instrument sensitivity to disturbances originating from digital circuitry. Refreshing of the data displayed on the screen occurs on every 2.5 seconds. The impulse peak detection is implemented through the differentiation of the amplified input signal, while the synchronization with the data coming from the converter output is established by taking advantage of the internal 'pipeline' structure of the converter itself. The mode of operation of the built-in microcontroller provides that there are no missed impulses, and the simple logic network prevents the initiation of the amplitude reading sequence for the next impulse in case it appears shortly after its precedent. The solution proposed here demonstrated a good performance at a comparatively low manufacturing cost, and is thus suitable for educational purposes (author)
Getting superstring amplitudes by degenerating Riemann surfaces
International Nuclear Information System (INIS)
Matone, Marco; Volpato, Roberto
2010-01-01
We explicitly show how the chiral superstring amplitudes can be obtained through factorisation of the higher genus chiral measure induced by suitable degenerations of Riemann surfaces. This powerful tool also allows to derive, at any genera, consistency relations involving the amplitudes and the measure. A key point concerns the choice of the local coordinate at the node on degenerate Riemann surfaces that greatly simplifies the computations. As a first application, starting from recent ansaetze for the chiral measure up to genus five, we compute the chiral two-point function for massless Neveu-Schwarz states at genus two, three and four. For genus higher than three, these computations include some new corrections to the conjectural formulae appeared so far in the literature. After GSO projection, the two-point function vanishes at genus two and three, as expected from space-time supersymmetry arguments, but not at genus four. This suggests that the ansatz for the superstring measure should be corrected for genus higher than four.
The Construction of Spin Foam Vertex Amplitudes
Directory of Open Access Journals (Sweden)
Eugenio Bianchi
2013-01-01
Full Text Available Spin foam vertex amplitudes are the key ingredient of spin foam models for quantum gravity. These fall into the realm of discretized path integral, and can be seen as generalized lattice gauge theories. They can be seen as an attempt at a 4-dimensional generalization of the Ponzano-Regge model for 3d quantum gravity. We motivate and review the construction of the vertex amplitudes of recent spin foam models, giving two different and complementary perspectives of this construction. The first proceeds by extracting geometric configurations from a topological theory of the BF type, and can be seen to be in the tradition of the work of Barrett, Crane, Freidel and Krasnov. The second keeps closer contact to the structure of Loop Quantum Gravity and tries to identify an appropriate set of constraints to define a Lorentz-invariant interaction of its quanta of space. This approach is in the tradition of the work of Smolin, Markopoulous, Engle, Pereira, Rovelli and Livine.
Asenov, Asen; Balasubramaniam, R.; Brown, A. R.; Davies, J. H.; Saini, Subhash
2000-01-01
In this paper we use 3D simulations to study the amplitudes of random telegraph signals (RTS) associated with the trapping of a single carrier in interface states in the channel of sub 100 nm (decanano) MOSFETs. Both simulations using continuous doping charge and random discrete dopants in the active region of the MOSFETs are presented. We have studied the dependence of the RTS amplitudes on the position of the trapped charge in the channel and on the device design parameters. We have observed a significant increase in the maximum RTS amplitude when discrete random dopants are employed in the simulations.
International Nuclear Information System (INIS)
Westphal, T; Nijssen, R P L
2014-01-01
The effect of Constant Life Diagram (CLD) formulation on the fatigue life prediction under variable amplitude (VA) loading was investigated based on variable amplitude tests using three different load spectra representative for wind turbine loading. Next to the Wisper and WisperX spectra, the recently developed NewWisper2 spectrum was used. Based on these variable amplitude fatigue results the prediction accuracy of 4 CLD formulations is investigated. In the study a piecewise linear CLD based on the S-N curves for 9 load ratios compares favourably in terms of prediction accuracy and conservativeness. For the specific laminate used in this study Boerstra's Multislope model provides a good alternative at reduced test effort
Westphal, T.; Nijssen, R. P. L.
2014-12-01
The effect of Constant Life Diagram (CLD) formulation on the fatigue life prediction under variable amplitude (VA) loading was investigated based on variable amplitude tests using three different load spectra representative for wind turbine loading. Next to the Wisper and WisperX spectra, the recently developed NewWisper2 spectrum was used. Based on these variable amplitude fatigue results the prediction accuracy of 4 CLD formulations is investigated. In the study a piecewise linear CLD based on the S-N curves for 9 load ratios compares favourably in terms of prediction accuracy and conservativeness. For the specific laminate used in this study Boerstra's Multislope model provides a good alternative at reduced test effort.
Detection of smaller Jc region and damage in YBCO coated conductors by using permanent magnet method
International Nuclear Information System (INIS)
Hattori, K.; Saito, A.; Takano, Y.; Suzuki, T.; Yamada, H.; Takayama, T.; Kamitani, A.; Ohshima, S.
2011-01-01
We developed a non-destructive method for measuring the critical current density (J c ) in YBCO-coated conductors by using a permanent magnet (Sm 2 Co 17 ). J c could be determined from the repulsive force (F r ) generated between a permanent magnet and a coated conductor where shielding current flows. We also examined the influence of damage to the film on the J c distribution. The measured F r when the permanent magnet approached the cut part was smaller than that of the undamaged area. We developed a non-destructive method for measuring the critical current density (J c ) in YBCO-coated conductors by using a permanent magnet (Sm 2 Co 17 ). J c could be determined from the repulsive force (F r ) generated between a permanent magnet and a coated conductor where shielding current flows. We tried to detect a smaller J c region in the coated conductor by using the system. The J c distribution could be determined without influence from the thick copper film on YBCO thin film. We also examined the influence of damage to the film on the J c distribution. The surface of the coated conductors was cut by using a knife. The measured F r when the permanent magnet approached the cut part was smaller than that of the undamaged area. This J c measurement technique will be useful for detecting smaller J c regions and defects in coated conductors.
Fischer, Christopher; Bol, Linda; Pribesh, Shana
2011-01-01
This study investigated the extent to which higher-order thinking skills are promoted in social studies classes in high schools that are implementing smaller learning communities (SLCs). Data collection in this mixed-methods study included classroom observations and in-depth interviews. Findings indicated that higher-order thinking was rarely…
A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle
van Bolhuis, A.I.; Holsheimer, J.; Savelsberg, H.H.C.M.
2001-01-01
Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low
On the Measurements of Particles Smaller than 20 μM by Global Rainbow Refractometry
Saengkaew, S.; Bonin, D.; Gréh, G.
2007-06-01
The measurement of the thermo-chemical characteristics of particles under evaporation or cooling is a challenge. Among others techniques, Global Rainbow Refractometry (GRR) is potentially applicable to a large variety of realistic media. This paper is focused on refractive index measurements of particles smaller than 20 μm which are especially important to extract droplet temperature in spray combustion.
Schuman, Samuel
2011-01-01
This monograph focuses upon areas of special concern to those working with honors at smaller colleges and universities: mission, recruitment, facilities, administration, budget, and curriculum. In each area, the author makes some general suggestions about overall operating principles, note specific issues that can lead to difficulties, and suggest…
DEFF Research Database (Denmark)
Andersen, Thomas B.; Krustrup, Peter; Bendiksen, Mads
2016-01-01
The present study evaluated the effect of a smaller, lighter ball on kicking speed and technical-tactical and physical match performance in high-level adult female footballers. In the laboratory test setting, the peak ball velocity was 6% higher with the new ball (NB) than the standard ball (SB...
Smaller socioeconomic inequalities in health among women: the role of employment status
Stronks, K.; van de Mheen, H.; van den Bos, J.; Mackenbach, J. P.
1995-01-01
Socioeconomic inequalities in health are smaller among women than among men. In this paper, it is hypothesized that this is due to a gender difference in employment status. We used data from the baseline of a Dutch longitudinal study. The socioeconomic indicators were educational level of the
13 CFR 120.215 - What interest rates apply to smaller loans?
2010-01-01
... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What interest rates apply to... BUSINESS LOANS Policies Specific to 7(a) Loans Maturities; Interest Rates; Loan and Guarantee Amounts § 120.215 What interest rates apply to smaller loans? For a loan over $25,000 but not exceeding $50,000, the...
Smaller Is More Personal, and the Personal Gets Results. The Editor Reflects.
Erb, Tom
2001-01-01
Summarizes growing body of evidence relating small school size at elementary and middle grades to positive student outcomes. Notes that positive outcomes associated with small size relate to teacher commitment and effectiveness as well as student attachment, persistence, and performance. Concludes that smaller, more intimate schools are better…
2010-06-30
... DEPARTMENT OF EDUCATION [CFDA No. 84.215L] Office of Elementary and Secondary Education; Smaller...-Marshall, U.S. Department of Education, 400 Maryland Avenue, SW., room 3E308, Washington, DC 20202-6200..., in text or Adobe Portable Document Format (PDF) on the Internet at the following site: http://www.ed...
The role of interpretation in the internationalization of smaller brazilian firms
R.W. Seifert (Ralf); J. Child (John); S.B. Rodrigues (Suzana)
2012-01-01
textabstractAbstract This study considers how decision-makers in smaller firms interpret the means and conditions of internationalization, and how different modes of interpretation are likely to inform action choices in this process. Drawing on 58 qualitative interviews with the leaders of
What Research Tells Us about the Impact and Challenges of Smaller Learning Communities
Levine, Thomas H.
2010-01-01
In the United States, considerable financial and human resources have been devoted to breaking some large high schools into smaller learning communities (SLCs). This article reviews research that compares SLCs to comprehensive high schools on a variety of measures. Extant research neither supports nor refutes the promise of SLCs to improve…
van Rooij, S J H; Kennis, M; Sjouwerman, R; van den Heuvel, M P; Kahn, R S; Geuze, E
2015-01-01
BACKGROUND: Smaller hippocampal volume has often been observed in patients with post-traumatic stress disorder (PTSD). However, there is no consensus whether this is a result of stress/trauma exposure, or constitutes a vulnerability factor for the development of PTSD. Second, it is unclear whether
Human H-reflexes are smaller in difficult beam walking than in normal treadmill walking.
Llewellyn, M; Yang, J F; Prochazka, A
1990-01-01
Hoffman (H) reflexes were elicited from the soleus (SOL) muscle while subjects walked on a treadmill and on a narrow beam (3.5 cm wide, raised 34 cm from the floor). The speed of walking on the treadmill was selected for each subject to match the background activation level of their SOL muscle during beam walking. The normal reciprocal activation pattern of the tibialis anterior and SOL muscles in treadmill walking was replaced by a pattern dominated by co-contraction on the beam. In addition, the step cycle duration was more variable and the time spent in the swing phase was reduced on the beam. The H-reflexes were highly modulated in both tasks, the amplitude being high in the stance phase and low in the swing phase. The H-reflex amplitude was on average 40% lower during beam walking than treadmill walking. The relationship between the H-reflex amplitude and the SOL EMG level was quantified by a regression line relating the two variables. The slope of this line was on average 41% lower in beam walking than treadmill walking. The lower H-reflex gain observed in this study and the high level of fusimotor drive observed in cats performing similar tasks suggest that the two mechanisms which control the excitability of this reflex pathway (i.e. fusimotor action and control of transmission at the muscle spindle to moto-neuron synapse) may be controlled independently.
van Rooij, S J H; Kennis, M; Sjouwerman, R; van den Heuvel, M P; Kahn, R S; Geuze, E
2015-10-01
Smaller hippocampal volume has often been observed in patients with post-traumatic stress disorder (PTSD). However, there is no consensus whether this is a result of stress/trauma exposure, or constitutes a vulnerability factor for the development of PTSD. Second, it is unclear whether hippocampal volume normalizes with successful treatment of PTSD, or whether a smaller hippocampus is a risk factor for the persistence of PTSD. Magnetic resonance imaging (MRI) scans and clinical interviews were collected from 47 war veterans with PTSD, 25 healthy war veterans (combat controls) and 25 healthy non-military controls. All veterans were scanned a second time with a 6- to 8-month interval, during which PTSD patients received trauma-focused therapy. Based on post-treatment PTSD symptoms, patients were divided into a PTSD group who was in remission (n = 22) and a group in whom PTSD symptoms persisted (n = 22). MRI data were analysed with Freesurfer. Smaller left hippocampal volume was observed in PTSD patients compared with both control groups. Hippocampal volume of the combat controls did not differ from healthy controls. Second, pre- and post-treatment analyses of the PTSD patients and combat controls revealed reduced (left) hippocampal volume only in the persistent patients at both time points. Importantly, hippocampal volume did not change with treatment. Our findings suggest that a smaller (left) hippocampus is not the result of stress/trauma exposure. Furthermore, hippocampal volume does not increase with successful treatment. Instead, we demonstrate for the first time that a smaller (left) hippocampus constitutes a risk factor for the persistence of PTSD.
HIV Distal Neuropathic Pain Is Associated with Smaller Ventral Posterior Cingulate Cortex.
Keltner, John R; Connolly, Colm G; Vaida, Florin; Jenkinson, Mark; Fennema-Notestine, Christine; Archibald, Sarah; Akkari, Cherine; Schlein, Alexandra; Lee, Jisu; Wang, Dongzhe; Kim, Sung; Li, Han; Rennels, Austin; Miller, David J; Kesidis, George; Franklin, Donald R; Sanders, Chelsea; Corkran, Stephanie; Grant, Igor; Brown, Gregory G; Atkinson, J Hampton; Ellis, Ronald J
2017-03-01
. Despite modern antiretroviral therapy, HIV-associated neuropathy is one of the most prevalent, disabling and treatment-resistant complications of HIV disease. The presence and intensity of distal neuropathic pain is not fully explained by the degree of peripheral nerve damage. A better understanding of brain structure in HIV distal neuropathic pain may help explain why some patients with HIV neuropathy report pain while the majority does not. Previously, we reported that more intense distal neuropathic pain was associated with smaller total cerebral cortical gray matter volumes. The objective of this study was to determine which parts of the cortex are smaller. . HIV positive individuals with and without distal neuropathic pain enrolled in the multisite (N = 233) CNS HIV Antiretroviral Treatment Effects (CHARTER) study underwent structural brain magnetic resonance imaging. Voxel-based morphometry was used to investigate regional brain volumes in these structural brain images. . Left ventral posterior cingulate cortex was smaller for HIV positive individuals with versus without distal neuropathic pain (peak P = 0.017; peak t = 5.15; MNI coordinates x = -6, y = -54, z = 20). Regional brain volumes within cortical gray matter structures typically associated with pain processing were also smaller for HIV positive individuals having higher intensity ratings of distal neuropathic pain. . The posterior cingulate is thought to be involved in inhibiting the perception of painful stimuli. Mechanistically a smaller posterior cingulate cortex structure may be related to reduced anti-nociception contributing to increased distal neuropathic pain. © 2016 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com
Reproductive cycles in tropical intertidal gastropods are timed around tidal amplitude cycles.
Collin, Rachel; Kerr, Kecia; Contolini, Gina; Ochoa, Isis
2017-08-01
Reproduction in iteroparous marine organisms is often timed with abiotic cycles and may follow lunar, tidal amplitude, or daily cycles. Among intertidal marine invertebrates, decapods are well known to time larval release to coincide with large amplitude nighttime tides, which minimizes the risk of predation. Such bimonthly cycles have been reported for few other intertidal invertebrates. We documented the reproduction of 6 gastropod species from Panama to determine whether they demonstrate reproductive cycles, whether these cycles follow a 2-week cycle, and whether cycles are timed so that larval release occurs during large amplitude tides. Two of the species ( Crepidula cf. marginalis and Nerita scabricosta ) showed nonuniform reproduction, but without clear peaks in timing relative to tidal or lunar cycles. The other 4 species show clear peaks in reproduction occurring every 2 weeks. In 3 of these species ( Cerithideopsis carlifornica var. valida, Littoraria variegata , and Natica chemnitzi ), hatching occurred within 4 days of the maximum amplitude tides. Siphonaria palmata exhibit strong cycles, but reproduction occurred during the neap tides. Strong differences in the intensity of reproduction of Cerithideopsis carlifornica , and in particular, Littoraria variegata , between the larger and smaller spring tides of a lunar month indicate that these species time reproduction with the tidal amplitude cycle rather than the lunar cycle. For those species that reproduce during both the wet and dry seasons, we found that reproductive timing did not differ between seasons despite strong differences in temperature and precipitation. Overall, we found that most (4/6) species have strong reproductive cycles synchronized with the tidal amplitude cycle and that seasonal differences in abiotic factors do not alter these cycles.
Kawamura, Y; Kanegae, R
2016-06-17
Cooling the vibration amplitude of a microcantilever as low as possible is important to improve the sensitivity and resolutions of various types of scanning type microscopes and sensors making use of it. When the vibration amplitude is controlled to be smaller using a feed back control system, it is known that the obtainable minimum amplitude of the vibration is limited by the floor noise level of the detection system. In this study, we demonstrated that the amplitude of the thermal vibration of a microcantilever was suppressed to be about 0.15 pmHz(-1/2), which is the same value with the floor noise level, without the assistance of external cryogenic cooling. We think that one of the reason why we could reach the smaller amplitude at room temperature is due to stiffer spring constant of the lever, which leads to higher natural frequency and consequently lower floor noise level. The other reason is considered to be due to the increase in the laser power for the diagnostics, which lead to the decrease in the signal to noise ratio determined by the optical shot noise.
Cross channel isospin amplitude analysis of the reaction pN→NNπ at 19 GeV/c
International Nuclear Information System (INIS)
Bakken, V.; Gennow, H.; Hansen, J.D.; Lundborg, P.; Maekelae, J.; Pimiae, M.; Sellden, B.; Skjevling, G.; Sundell, E.
1976-10-01
The reaction N 1 N 2 →N 3 (N 4 π) is analysed in terms of three isospin amplitudes Msub(I)sup(Isub(x)) where Isub(x) and I are the isospin of the exchanged particle and the N 4 π combination respectively. The amplitudes are studied as functions of the momentum transfer to and the mass of the N 4 π system. The M 0 sub(1/2) amplitude exhibits the characteristics of diffraction dissociation with a broad low mass enhancement centered around 1.35 GeV. The dsigma/dt' distribution of M 0 sub(1/2) shows a clear break around 0.2 (GeV/c) 2 for masses smaller than 1.36 GeV. For higher masses the break disappears and the slope of the forward peak becomes smaller. The interference between M 0 sub(1/2) and M 1 sub(1/2) is zero for small values of t' and becomes large in magnitude and negative for larger t' values. The other interference terms are consistent with being zero. The hypothesis of factorization is tested for the M 0 sub(1/2) amplitude by comparison with the corresponding amplitude of π +- N reactions. The agreement is excellent over the whole mass range. (Auth.)
Thrombelastography Early Amplitudes in bleeding and coagulopathic trauma patients
DEFF Research Database (Denmark)
Laursen, Thomas Holst; Meyer, Martin A S; Meyer, Anna Sina P
2018-01-01
BACKGROUND: Early amplitudes in the viscoelastic hemostatic assays Thrombelastography (TEG) and Rotation Thromboelastometry (ROTEM) provide fast results, which is critical in resuscitation of bleeding patients. This study investigated associations between TEG early amplitudes and standard TEG var...
Variational principles for the projected breakup amplitude
International Nuclear Information System (INIS)
Hahn, Y.
1976-01-01
Two alternate forms of variational principles for the breakup amplitude describing the two- to three-cluster transition are derived such that all the integrals involved in the intermediate stages are well defined. The first form contains a trial Green's function with which both the initial and final state trial wave functions are constructed. The earlier form of the Kohn-type variational principle derived by Lieber, Rosenberg, and Spruch is recovered, however, when this connection between the trial functions is removed. The second form of the variational principle is derived by projecting out from the trial functions all the open channel components which correspond to the two-cluster structures including the rearrangement channels. The remaining part of the wave functions describes the channels with three-cluster structures, and the integrals involving this part are then mathematically well defined
Single isospin decay amplitude and CP violation
Energy Technology Data Exchange (ETDEWEB)
Deshpande, N.G. [Oregon Univ., Eugene, OR (United States). Inst. of Theoretical Science; He, Xiaogang [Melbourne Univ., Parkville, VIC (Australia). School of Physics; Pakvasa, S. [Hawaii Univ., Honolulu, HI (United States). Dept. of Physics and Astronomy
1996-06-01
While for K meson or hyperon decays, the partial rate asymmetries are always zero if the final states are single isospin states, in B decays the situation is dramatically different and partial rate asymmetries can be non-zero if the final states are single isospin states. Partial rate asymmetries were calculated for several B decays with single isospin amplitude in the finale states using factorization approximation. It was found that more intermediate on-shell states with different Cabbibbo-Kobayashi-Maskawa factors are allowed in B decay and CP violating partial rate asymmetries need not to be zero even if the final state contains only a single isospin state. 17 refs., 4 figs.
Large amplitude parallel propagating electromagnetic oscillitons
International Nuclear Information System (INIS)
Cattaert, Tom; Verheest, Frank
2005-01-01
Earlier systematic nonlinear treatments of parallel propagating electromagnetic waves have been given within a fluid dynamic approach, in a frame where the nonlinear structures are stationary and various constraining first integrals can be obtained. This has lead to the concept of oscillitons that has found application in various space plasmas. The present paper differs in three main aspects from the previous studies: first, the invariants are derived in the plasma frame, as customary in the Sagdeev method, thus retaining in Maxwell's equations all possible effects. Second, a single differential equation is obtained for the parallel fluid velocity, in a form reminiscent of the Sagdeev integrals, hence allowing a fully nonlinear discussion of the oscilliton properties, at such amplitudes as the underlying Mach number restrictions allow. Third, the transition to weakly nonlinear whistler oscillitons is done in an analytical rather than a numerical fashion
Amplitude and phase modulation with waveguide optics
International Nuclear Information System (INIS)
Burkhart, S.C.; Wilcox, R.B.; Browning, D.; Penko, F.A.
1996-01-01
We have developed amplitude and phase modulation systems for glass lasers using integrated electro-optic modulators and solid state high-speed electronics. The present and future generation of lasers for Inertial Confinement Fusion require laser beams with complex temporal and phase shaping to compensate for laser gain saturation, mitigate parametric processes such as transverse stimulated Brillouin scattering in optics, and to provide specialized drive to the fusion targets. These functions can be performed using bulk optoelectronic modulators, however using high-speed electronics to drive low voltage integrated optical modulators has many practical advantages. In particular, we utilize microwave GaAs transistors to perform precision, 250 ps resolution temporal shaping. Optical bandwidth is generated using a microwave oscillator at 3 GHz amplified by a solid state amplifier. This drives an integrated electrooptic modulator to achieve laser bandwidths exceeding 30 GHz
Topological amplitudes in heterotic superstring theory
International Nuclear Information System (INIS)
Antoniadis, I.; Taylor, T.R.
1996-06-01
We show that certain heterotic string amplitudes are given in terms of correlators of the twisted topological (2,0) SCFT, corresponding to the internal sector of the N = 1 spacetime supersymmetric background. The genus g topological partition function F g corresponds to a term in the effective action of the form W 2g , where W is the gauge or gravitational superfield. We study also recursion relations related to holomorphic anomalies, showing that, contrary to the type II case, they involve correlators of anti-chiral superfields. The corresponding terms in the effective action are of the form W 2g II n , where II is a chiral superfield obtained by chiral projection of a general superfield. We observe that the structure of the recursion relations is that of N = 1 spacetime supersymmetry Ward identity. We give also a solution of the tree level recursion relations and discuss orbifold examples. (author). 23 refs, 2 figs
Polynomial structures in one-loop amplitudes
International Nuclear Information System (INIS)
Britto, Ruth; Feng Bo; Yang Gang
2008-01-01
A general one-loop scattering amplitude may be expanded in terms of master integrals. The coefficients of the master integrals can be obtained from tree-level input in a two-step process. First, use known formulas to write the coefficients of (4-2ε)-dimensional master integrals; these formulas depend on an additional variable, u, which encodes the dimensional shift. Second, convert the u-dependent coefficients of (4-2ε)-dimensional master integrals to explicit coefficients of dimensionally shifted master integrals. This procedure requires the initial formulas for coefficients to have polynomial dependence on u. Here, we give a proof of this property in the case of massless propagators. The proof is constructive. Thus, as a byproduct, we produce different algebraic expressions for the scalar integral coefficients, in which the polynomial property is apparent. In these formulas, the box and pentagon contributions are separated explicitly.
Amplitude correlations for inelastic proton scattering from 48Ti
International Nuclear Information System (INIS)
Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.
1981-01-01
The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 45 5/2 + resonances in 49 V. The reduced widths in each channel follow a Porter-Thomas distribution, but extremely large amplitude correlations are observed - for one pair of channel amplitudes the relative sign is positive for 43 of 45 resonances. These results provide the first direct test of the Krieger-Porter reduced width amplitude distribution. (orig.)
Tree-level gluon amplitudes on the celestial sphere
Schreiber, Anders Ø.; Volovich, Anastasia; Zlotnikov, Michael
2018-06-01
Pasterski, Shao and Strominger have recently proposed that massless scattering amplitudes can be mapped to correlators on the celestial sphere at infinity via a Mellin transform. We apply this prescription to arbitrary n-point tree-level gluon amplitudes. The Mellin transforms of MHV amplitudes are given by generalized hypergeometric functions on the Grassmannian Gr (4 , n), while generic non-MHV amplitudes are given by more complicated Gelfand A-hypergeometric functions.
Correlations for reduced-width amplitudes in 49V
International Nuclear Information System (INIS)
Chou, B.H.; Mitchell, G.E.; Bilpuch, E.G.; Westerfeldt, C.R.
1980-01-01
Measurement of the relative sign of inelastic proton-channel amplitudes permits the determination of amplitude correlations. Data were obtained for 45 5/2 + resonances in 49 V. Although the reduced widths in each channel followed a Porter-Thomas distribution, large amplitude correlations were observed. The results are compared with the reduced-width--amplitude distribution of Krieger and Porter. This is the first direct test of the Krieger-Porter distribution
MHV Vertices And Tree Amplitudes In Gauge Theory
International Nuclear Information System (INIS)
Cachazo, Freddy; Svrcek, Peter; Witten, Edward
2004-01-01
As an alternative to the usual Feynman graphs, tree amplitudes in Yang-Mills theory can be constructed from tree graphs in which the vertices are tree level MHV scattering amplitudes, continued off shell in a particular fashion. The formalism leads to new and relatively simple formulas for many amplitudes, and can be heuristically derived from twistor space. (author)
Investigation of a mutual interaction force at different pressure amplitudes in sulfuric acid
International Nuclear Information System (INIS)
Rezaee, Nastaran; Sadighi-Bonabi, Rasoul; Mirheydari, Mona; Ebrahimi, Homa
2011-01-01
This paper investigates the secondary Bjerknes force for two oscillating bubbles in various pressure amplitudes in a concentration of 95% sulfuric acid. The equilibrium radii of the bubbles are assumed to be smaller than 10 μm at a frequency of 37 kHz in various strong driving acoustical fields around 2.0 bars (1 bar=10 5 Pa). The secondary Bjerknes force is investigated in uncoupled and coupled states between the bubbles, with regard to the quasi-adiabatic model for the bubble interior. It finds that the value of the secondary Bjerknes force depends on the driven pressure of sulfuric acid and its amount would be increased by liquid pressure amplitude enhancement. The results show that the repulsion area of the interaction force would be increased by increasing the driven pressure because of nonlinear oscillation of bubbles. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Smith, T.; Arce, A. C.; Ji, C.
2016-12-01
Waveform cross-correlation technique is widely used to improve the detection of small magnitude events induced by hydraulic fracturing. However, when events are detected, assigning a reliable magnitude is a challenging task, especially considering their small signal amplitude and high background noise during injections. In this study, we adopt the Match & Locate algorithm (M&L, Zhang and Wen, 2015) to analyze seven hours of continuous seismic observations from a hydraulic fracturing experiment in Central California. The site of the stimulated region is only 300-400m away from a 16-receiver vertical-borehole array which spans 230 m. The sampling rate is 4000 Hz. Both the injection sites and borehole array are more than 1.7 km below the surface. This dataset has previously been studied by an industry group, producing a catalog of 1134 events with moment magnitudes (Mw) ranging from -3.1 to -0.9. In this study, we select 202 events from this catalog with high signal to noise ratios to use as templates. Our M&L analysis produces a new catalog that contains 2119 events, which is 10 times more detections than the number of templates and about two times the original catalog. Using these two catalogs, we investigate the relationship of moment magnitude difference (ΔMW) and local magnitude difference (ΔML) between the detected event and corresponding template event. ΔML is computed using the peak amplitude ratio between the detected and template event for each channel. Our analysis yields an empirical relationship of ΔMW=0.64-0.65ΔML with an R2 of 0.99. The coefficient of 2/3 suggests that the information of the event's corner frequency is entirely lost (Hanks and Boore, 1984). The cause might not be unique, which implies that Earth's attenuation at this depth range (>1.7 km) is significant; or the 4000 Hz sampling rate is not sufficient. This relationship is crucial to estimate the b-value of the microseismicity induced by hydraulic fracture experiments. The analysis
Desirable airfoil features for smaller-capacity straight-bladed VAWT
Energy Technology Data Exchange (ETDEWEB)
Islam, Mazharul; Ting, D.S.-K.; Fartaj, Amir
2007-05-15
In the small scale wind turbine market, the simple straight-bladed Darrieus type vertical axis wind turbine (SB-VAWT) is very attractive for its simple blade design. A detailed aerodynamic performance analysis was conducted on a smaller capacity fixed-pitch SB-VAWT. Brief analyses of the main aerodynamic challenges of this type of wind turbine were first discussed and subsequently the authors conducted further literature survey and computational analysis to shortlist aerodynamic characteristics of a desirable airfoil for a self-starting and better performing SB-VAWT. The required geometric features of the desirable airfoil to achieve the short listed characteristics were also discussed. It has been found out that conventionally used NACA symmetric airfoils are not suitable for smaller capacity SB-VAWT. Rather, it is advantageous to utilize a high-lift and low-drag asymmetric thick airfoil suitable for low speed operation typically encountered by SB-VAWT. (author)
How food marketers can sell smaller portions: Consumer insights and product innovation.
Riis, J; Fisher, J O; Rowe, S
2016-08-01
Food portion size has been shown to be an important driver of energy intake. Despite the well acknowledged role of portion control in weight management, large portion sizes remain ubiquitous in the marketplace. Moving consumers towards consumption of smaller portion sizes will require changes in consumer behavior as well as changes in products available to consumers in a variety of settings. This special supplement presents cutting edge research aimed at understanding consumer behavior around portion size and innovations in product design that may promote the selection and consumption of smaller portion sizes. We identify further research that will be needed to translate basic behavioral findings into real world settings and to viable product development. Copyright © 2016. Published by Elsevier Ltd.
Effects of a lighter, smaller football on Acute match injuries in adolescent female football
DEFF Research Database (Denmark)
Zebis, Mette K.; Thorborg, Kristian; Andersen, Lars L.
2018-01-01
BACKGROUND: The high injury incidence during match-play in female adolescent football is a major concern. In football, males and females play matches with the same football size. No studies have investigated the effect of football size on injury incidence in female adolescent football. Thus......, the aim of the present study was to investigate the effects of introducing a lighter, smaller football on the injury pattern in female adolescent football. METHODS We conducted a pilot cluster randomized controlled trial including 26 football teams representing 346 adolescent female football players (age...... 15-18 years). The teams were randomized to a new lighter, smaller football (INT, N.=12 teams) or a traditional FIFA size 5 football (CON, N.=14 teams) during a full match-season. Acute time-loss injuries and football-exposure during match-play were reported weekly by text-message questions...
Media bias under direct and indirect government control: when is the bias smaller?
Abhra Roy
2015-01-01
We present an analytical framework to compare media bias under direct and indirect government control. In this context, we show that direct control can lead to a smaller bias and higher welfare than indirect control. We further show that the size of the advertising market affects media bias only under direct control. Media bias, under indirect control, is not affected by the size of the advertising market.
Plant Proteins Are Smaller Because They Are Encoded by Fewer Exons than Animal Proteins.
Ramírez-Sánchez, Obed; Pérez-Rodríguez, Paulino; Delaye, Luis; Tiessen, Axel
2016-12-01
Protein size is an important biochemical feature since longer proteins can harbor more domains and therefore can display more biological functionalities than shorter proteins. We found remarkable differences in protein length, exon structure, and domain count among different phylogenetic lineages. While eukaryotic proteins have an average size of 472 amino acid residues (aa), average protein sizes in plant genomes are smaller than those of animals and fungi. Proteins unique to plants are ∼81aa shorter than plant proteins conserved among other eukaryotic lineages. The smaller average size of plant proteins could neither be explained by endosymbiosis nor subcellular compartmentation nor exon size, but rather due to exon number. Metazoan proteins are encoded on average by ∼10 exons of small size [∼176 nucleotides (nt)]. Streptophyta have on average only ∼5.7 exons of medium size (∼230nt). Multicellular species code for large proteins by increasing the exon number, while most unicellular organisms employ rather larger exons (>400nt). Among subcellular compartments, membrane proteins are the largest (∼520aa), whereas the smallest proteins correspond to the gene ontology group of ribosome (∼240aa). Plant genes are encoded by half the number of exons and also contain fewer domains than animal proteins on average. Interestingly, endosymbiotic proteins that migrated to the plant nucleus became larger than their cyanobacterial orthologs. We thus conclude that plants have proteins larger than bacteria but smaller than animals or fungi. Compared to the average of eukaryotic species, plants have ∼34% more but ∼20% smaller proteins. This suggests that photosynthetic organisms are unique and deserve therefore special attention with regard to the evolutionary forces acting on their genomes and proteomes. Copyright © 2016 The Authors. Production and hosting by Elsevier Ltd.. All rights reserved.
Knowledge acquisition for the internationalization of the smaller firm:Content and sources
Harris, Simon; Fletcher, Margaret
2012-01-01
Internationalization process research emphasizes accumulated experience and networks as sources of knowledge for internationalization. Our understanding, however, as to what this knowledge is in practice for smaller firms, the challenges they face in acquiring it, and how they address those challenges is limited. Integrating organizational learning concepts with our theoretical understanding of the small firm internationalization process, we develop a new framework for understanding knowledge...
Plant Proteins Are Smaller Because They Are Encoded by Fewer Exons than Animal Proteins
Directory of Open Access Journals (Sweden)
Obed Ramírez-Sánchez
2016-12-01
Full Text Available Protein size is an important biochemical feature since longer proteins can harbor more domains and therefore can display more biological functionalities than shorter proteins. We found remarkable differences in protein length, exon structure, and domain count among different phylogenetic lineages. While eukaryotic proteins have an average size of 472 amino acid residues (aa, average protein sizes in plant genomes are smaller than those of animals and fungi. Proteins unique to plants are ∼81 aa shorter than plant proteins conserved among other eukaryotic lineages. The smaller average size of plant proteins could neither be explained by endosymbiosis nor subcellular compartmentation nor exon size, but rather due to exon number. Metazoan proteins are encoded on average by ∼10 exons of small size [∼176 nucleotides (nt]. Streptophyta have on average only ∼5.7 exons of medium size (∼230 nt. Multicellular species code for large proteins by increasing the exon number, while most unicellular organisms employ rather larger exons (>400 nt. Among subcellular compartments, membrane proteins are the largest (∼520 aa, whereas the smallest proteins correspond to the gene ontology group of ribosome (∼240 aa. Plant genes are encoded by half the number of exons and also contain fewer domains than animal proteins on average. Interestingly, endosymbiotic proteins that migrated to the plant nucleus became larger than their cyanobacterial orthologs. We thus conclude that plants have proteins larger than bacteria but smaller than animals or fungi. Compared to the average of eukaryotic species, plants have ∼34% more but ∼20% smaller proteins. This suggests that photosynthetic organisms are unique and deserve therefore special attention with regard to the evolutionary forces acting on their genomes and proteomes.
Trends and patterns in contemporary management in smaller companies: The Danish perspective
Ulhøi, John Parm; Madsen, Henning
2001-01-01
This paper reports empirical findings from a recent survey of Danish managers with a special focus on managers from smaller companies. The survey has been initiated in Denmark and it is called the 'Danish Management Barometer'. The project is a joint research program between the Aarhus School of Business and the Danish Association of Managers and Executives. It is based on a structured, pre-tested questionnaire send out to 1500 pre-notified managers in Denmark aiming at establishing a...
Moran, Kenneth A
2016-06-04
analysis was used to examine the direct and interaction effects between organizational decline, organizational rigidity response, organizational resilience response, and institutional effectiveness, controlling for age of institution and level of endowment. The study validated previous threat-rigidity response findings that organizational decline alone does not adversely impact institutional effectiveness. The direct effect of Goal-Directed Solution Seeking and Role Dependency organizational resilience factors had a positive, significant correlation with the Student Personal Development institutional effectiveness factor. The interactive effect of Goal-Directed Solution Seeking organizational resilience factor during organizational decline had a positive, significant correlation with the Professional Development and Quality of Faculty institutional effectiveness factor. The interactive effect of Avoidance during organizational decline had a positive, significant correlation with the Faculty and Administrator Employment Satisfaction institutional effectiveness factor. The interactive effect of Diminished Innovation, Morale, and Leader Credibility rigidity response factor and Avoidance organizational resilience factor during organizational decline had a positive, significant correlation with the Professional Development and Quality of Faculty institutional effectiveness factor. Lastly, the interactive effect of Increased Scapegoating of Leaders, Interest group Activities, and Conflict rigidity response factor and Avoidance organizational resilience factor during organizational decline had a positive, significant correlation with the Faculty and Administrator Employment Satisfaction institutional effectiveness factor. Factors of organizational resilience were found to have a positive effect among smaller, private non-profit higher educational institutions associated with this study toward sustaining institutional effectiveness during organizational decline. Specifically, the
Non-supersymmetric loop amplitudes and MHV vertices
International Nuclear Information System (INIS)
Bedford, James; Brandhuber, Andreas; Spence, Bill; Travaglini, Gabriele
2005-01-01
We show how the MHV diagram description of Yang-Mills theories can be used to study non-supersymmetric loop amplitudes. In particular, we derive a compact expression for the cut-constructible part of the general one-loop MHV multi-gluon scattering amplitude in pure Yang-Mills theory. We show that in special cases this expression reduces to known amplitudes-the amplitude with adjacent negative-helicity gluons, and the five gluon non-adjacent amplitude. Finally, we briefly discuss the twistor space interpretation of our result
Phase and amplitude detection system for the Stanford Linear Accelerator
International Nuclear Information System (INIS)
Fox, J.D.; Schwarz, H.D.
1983-01-01
A computer controlled phase and amplitude detection system to measure and stabilize the rf power sources in the Stanford Linear Accelerator is described. This system measures the instantaneous phase and amplitude of a 1 microsecond 2856 MHz rf pulse and will be used for phase feedback control and for amplitude and phase jitter detection. This paper discusses the measurement system performance requirements for the operation of the Stanford Linear Collider, and the design and implementation of the phase and amplitude detection system. The fundamental software algorithms used in the measurement are described, as is the performance of the prototype phase and amplitude detector system
Amplitude and phase fluctuations of Van der Pol oscillator under external random forcing
Singh, Aman K.; Yadava, R. D. S.
2018-05-01
The paper presents an analytical study of noise in Van der Pol oscillator output subjected to an external force noise assumed to be characterized by delta function (white noise). The external fluctuations are assumed to be small in comparison to the average response of the noise free system. The autocorrelation function and power spectrum are calculated under the condition of weak nonlinearity. The latter ensures limit cycle oscillations. The total spectral power density is dominated by the contributions from the phase fluctuations. The amplitude fluctuations are at least two orders of magnitude smaller. The analysis is shown to be useful to interpretation microcantilever based biosensing data.
Amplitude modulation in δ Sct stars: statistics from an ensemble of Kepler targets
Bowman, Dominic M.; Kurtz, Donald W.; Breger, Michel; Murphy, Simon J.; Holdsworth, Daniel L.
2017-10-01
The results of a search for amplitude modulation of pulsation modes in 983 δ Sct stars, which have effective temperatures between 6400 ⩽ Teff ⩽ 10 000 K in the Kepler Input Catalogue and were continuously observed by the Kepler Space Telescope for 4 yr, are presented. A total of 603 δ Sct stars (61.3 per cent) are found to exhibit at least one pulsation mode that varies significantly in amplitude over 4 yr. Furthermore, it is found that amplitude modulation is not restricted to a specific region within the classical instability strip in the HR diagram, therefore its cause is not necessarily dependent on stellar parameters such as Teff or log g. On the other hand, many δ Sct stars show constant pulsation amplitudes demonstrating that the cause of pulsational non-linearity in these stars is not well understood.
Flat-Cladding Fiber Bragg Grating Sensors for Large Strain Amplitude Fatigue Tests
Directory of Open Access Journals (Sweden)
Xijia Gu
2010-08-01
Full Text Available We have successfully developed a flat-cladding fiber Bragg grating sensor for large cyclic strain amplitude tests of up to ±8,000 με. The increased contact area between the flat-cladding fiber and substrate, together with the application of a new bonding process, has significantly increased the bonding strength. In the push-pull fatigue tests of an aluminum alloy, the plastic strain amplitudes measured by three optical fiber sensors differ only by 0.43% at a cyclic strain amplitude of ±7,000 με and 1.9% at a cyclic strain amplitude of ±8,000 με. We also applied the sensor on an extruded magnesium alloy for evaluating the peculiar asymmetric hysteresis loops. The results obtained were in good agreement with those measured from the extensometer, a further validation of the sensor.
Leading Wave Amplitude of a Tsunami
Kanoglu, U.
2015-12-01
Okal and Synolakis (EGU General Assembly 2015, Geophysical Research Abstracts-Vol. 17-7622) recently discussed that why the maximum amplitude of a tsunami might not occur for the first wave. Okal and Synolakis list observations from 2011 Japan tsunami, which reached to Papeete, Tahiti with a fourth wave being largest and 72 min later after the first wave; 1960 Chilean tsunami reached Hilo, Hawaii with a maximum wave arriving 1 hour later with a height of 5m, first wave being only 1.2m. Largest later waves is a problem not only for local authorities both in terms of warning to the public and rescue efforts but also mislead the public thinking that it is safe to return shoreline or evacuated site after arrival of the first wave. Okal and Synolakis considered Hammack's (1972, Ph.D. Dissertation, Calif. Inst. Tech., 261 pp., Pasadena) linear dispersive analytical solution with a tsunami generation through an uplifting of a circular plug on the ocean floor. They performed parametric study for the radius of the plug and the depth of the ocean since these are the independent scaling lengths in the problem. They identified transition distance, as the second wave being larger, regarding the parameters of the problem. Here, we extend their analysis to an initial wave field with a finite crest length and, in addition, to a most common tsunami initial wave form of N-wave as presented by Tadepalli and Synolakis (1994, Proc. R. Soc. A: Math. Phys. Eng. Sci., 445, 99-112). We compare our results with non-dispersive linear shallow water wave results as presented by Kanoglu et al. (2013, Proc. R. Soc. A: Math. Phys. Eng. Sci., 469, 20130015), investigating focusing feature. We discuss the results both in terms of leading wave amplitude and tsunami focusing. Acknowledgment: The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no 603839 (Project ASTARTE - Assessment, Strategy and Risk
Effects of amplitude modulation on perception of wind turbine noise
Energy Technology Data Exchange (ETDEWEB)
Yoon, Ki Seop; Lee, Soo Gab; Gwak, Doo Young [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Seong, Yeol Wan [Ammunition Engineering Team, Defense Agency for Technology and Quality, Daejeon (Korea, Republic of); Lee, Seung Hoon [Aerodynamics Research Team, Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Hong, Ji Young [Transportation Environmental Research Team, Green Transport and Logistics Institute, Korea Railroad Research Institute, Uiwang (Korea, Republic of)
2016-10-15
Wind turbine noise is considered to be easily detectable and highly annoying at relatively lower sound levels than other noise sources. Many previous studies attributed this characteristic to amplitude modulation. However, it is unclear whether amplitude modulation is the main cause of these properties of wind turbine noise. Therefore, the aim of the current study is to identify the relationship between amplitude modulation and these two properties of wind turbine noise. For this investigation, two experiments were conducted. In the first experiment, 12 participants determined the detection thresholds of six target sounds in the presence of background noise. In the second experiment, 12 participants matched the loudness of modified sounds without amplitude modulation to that of target sounds with amplitude modulation. The results showed that the detection threshold was lowered as the modulation depth increased; additionally, sounds with amplitude modulation had higher subjective loudness than those without amplitude modulation.
Effects of amplitude modulation on perception of wind turbine noise
International Nuclear Information System (INIS)
Yoon, Ki Seop; Lee, Soo Gab; Gwak, Doo Young; Seong, Yeol Wan; Lee, Seung Hoon; Hong, Ji Young
2016-01-01
Wind turbine noise is considered to be easily detectable and highly annoying at relatively lower sound levels than other noise sources. Many previous studies attributed this characteristic to amplitude modulation. However, it is unclear whether amplitude modulation is the main cause of these properties of wind turbine noise. Therefore, the aim of the current study is to identify the relationship between amplitude modulation and these two properties of wind turbine noise. For this investigation, two experiments were conducted. In the first experiment, 12 participants determined the detection thresholds of six target sounds in the presence of background noise. In the second experiment, 12 participants matched the loudness of modified sounds without amplitude modulation to that of target sounds with amplitude modulation. The results showed that the detection threshold was lowered as the modulation depth increased; additionally, sounds with amplitude modulation had higher subjective loudness than those without amplitude modulation
Reduction in plasmaspheric hiss wave amplitudes during a substorm
Li, H.; Yuan, Z.; Yu, X.; Deng, X.; Tang, R.; Chen, Z.; Zhou, M.; Huang, S.
2017-12-01
Plasmaspheric hiss is an important plasma wave in controlling the overall structure and dynamics of radiation belt electrons, so the distribution and generation mechanism of plasmaspheric hiss waves is worthy of study. Previous studies have found that the amplitude of plasmaspheric hiss waves tends to increase as substorm activity increases. In this study, through analysis of a hiss event observed by the Van Allen Radiation Belt Storm Probes (RBSP), it is found that the intensity of plasmaspheric hiss waves at magnetic local time (MLT) > 1300 (L≈5) is reduced or even disappears during a substorm. After calculating energetic electron trajectories, we suggest that this is because electrons are prevented from entering the plasmasphere at MLT > 1300 (L≈5) by the stronger convection electric field during the substorm. The calculations are consistent with direct observations from the RBSP satellites. The results highlight the significant and complex variability of plasmaspheric hiss waves. The amplitude of these waves on the dayside is not necessarily positively correlated with substorm activity, as negative correlations may be observed on the afternoon side during a substorm.
Tzvi, Elinor; Bauhaus, Leon J; Kessler, Till U; Liebrand, Matthias; Wöstmann, Malte; Krämer, Ulrike M
2018-03-01
Cross-frequency coupling is suggested to serve transfer of information between wide-spread neuronal assemblies and has been shown to underlie many cognitive functions including learning and memory. In previous work, we found that alpha (8-13 Hz) - gamma (30-48 Hz) phase amplitude coupling (αγPAC) is decreased during sequence learning in bilateral frontal cortex and right parietal cortex. We interpreted this to reflect decreased demands for visuo-motor mapping once the sequence has been encoded. In the present study, we put this hypothesis to the test by adding a "simple" condition to the standard serial reaction time task (SRTT) with minimal needs for visuo-motor mapping. The standard SRTT in our paradigm entailed a perceptual sequence allowing for implicit learning of a sequence of colors with randomly assigned motor responses. Sequence learning in this case was thus not associated with reduced demands for visuo-motor mapping. Analysis of oscillatory power revealed a learning-related alpha decrease pointing to a stronger recruitment of occipito-parietal areas when encoding the perceptual sequence. Replicating our previous findings but in contrast to our hypothesis, αγPAC was decreased in sequence compared to random trials over right frontal and parietal cortex. It also tended to be smaller compared to trials requiring a simple motor sequence. We additionally analyzed αγPAC in resting-state data of a separate cohort. PAC in electrodes over right parietal cortex was significantly stronger compared to sequence trials and tended to be higher compared to simple and random trials of the SRTT data. We suggest that αγPAC in right parietal cortex reflects a "default-mode" brain state, which gets perturbed to allow for encoding of visual regularities into memory. Copyright © 2018 Elsevier Inc. All rights reserved.
The pulsed amplitude unit for the SLC
International Nuclear Information System (INIS)
Rolfe, J.; Browne, M.J.; Jobe, R.K.
1987-02-01
There is a recurring requirement in the SLC for the control of devices such as magnets, phase shifters, and attenuators on a beam-by-beam basis. The Pulsed Amplitude Unit (PAU) is a single width CAMAC module developed for this purpose. It provides digitally programmed analog output voltages on a beam-by-beam basis. Up to 32 preprogrammed values of output voltage are available from the single analog output of the module, and any of these values can be associated with any of the 256 possible SLC beam definitions. A 12-bit Analog-to-Digital Converter (ADC) digitizes an analog input signal at the appropriate beam time and stores it in a buffer memory. This feature is normally used to monitor the response of the device being controlled by the PAU at each beam time. Initial application of the PAU is a part of the system that controls the output of Klystrons in the SLC. The PAU combines several different functions in a single module. In order to accommodate these functions in a single width CAMAC module, field programmed logic is used extensively. Field Programmable Logic Arrays, Programmed Array Logic, and a Field Programmable Logic Sequencer are employed
Gearbox Vibration Signal Amplitude and Frequency Modulation
Directory of Open Access Journals (Sweden)
Fakher Chaari
2012-01-01
Full Text Available Gearboxes usually run under fluctuating load conditions during service, however most of papers available in the literature describe models of gearboxes under stationary load conditions. Main task of published papers is fault modeling for their detection. Considering real situation from industry, the assumption of stationarity of load conditions cannot be longer kept. Vibration signals issued from monitoring in maintenance operations differ from mentioned models (due to load non-stationarity and may be difficult to analyze which lead to erroneous diagnosis of the system. The objective of this paper is to study the influence of time varying load conditions on a gearbox dynamic behavior. To investigate this, a simple spur gear system without defects is modeled. It is subjected to a time varying load. The speed-torque characteristic of the driving motor is considered. The load variation induces speed variation, which causes a variation in the gearmesh stiffness period. Computer simulation shows deep amplitude modulations with sidebands that don't differ from those obtained when there is a defective tooth. In order to put in evidence the time varying load effects, Short Time Fourier Transform and then Smoothed Wigner-Ville distribution are used. Results show that the last one is well suited for the studied case.
Electroweak amplitudes in chiral quark models
International Nuclear Information System (INIS)
Fiolhais, Manuel
2004-01-01
After referring to some basic features of chiral models for baryons, with quarks and mesons, we describe how to construct model states representing physical baryons. We consider soliton models such as the Linear Sigma Model or the Chromodielectric Model, and bag models such as the Cloudy Bag Model. These models are solved approximately using variational approaches whose starting point is a mean-field description. We go beyond the mean-field description by introducing quantum fluctuations in the mesonic degrees of freedom. This is achieved, in a first step, by using a quantum state to represent meson clouds and, secondly, by performing an angular momentum and isospin projection from the mean-field state (actually a coherent state). Model states for baryons (nucleon, Delta, Roper) constructed in this way are used to determine several physical properties. I this seminar we paid a particular attention to the nucleon-delta electromagnetic and weak transition, presenting the model predictions for the electromagnetic and axial amplitudes
Nonlinear amplitude dynamics in flagellar beating.
Oriola, David; Gadêlha, Hermes; Casademunt, Jaume
2017-03-01
The physical basis of flagellar and ciliary beating is a major problem in biology which is still far from completely understood. The fundamental cytoskeleton structure of cilia and flagella is the axoneme, a cylindrical array of microtubule doublets connected by passive cross-linkers and dynein motor proteins. The complex interplay of these elements leads to the generation of self-organized bending waves. Although many mathematical models have been proposed to understand this process, few attempts have been made to assess the role of dyneins on the nonlinear nature of the axoneme. Here, we investigate the nonlinear dynamics of flagella by considering an axonemal sliding control mechanism for dynein activity. This approach unveils the nonlinear selection of the oscillation amplitudes, which are typically either missed or prescribed in mathematical models. The explicit set of nonlinear equations are derived and solved numerically. Our analysis reveals the spatio-temporal dynamics of dynein populations and flagellum shape for different regimes of motor activity, medium viscosity and flagellum elasticity. Unstable modes saturate via the coupling of dynein kinetics and flagellum shape without the need of invoking a nonlinear axonemal response. Hence, our work reveals a novel mechanism for the saturation of unstable modes in axonemal beating.
An amplitude modulated radio frequency plasma generator
Lei, Fan; Li, Xiaoping; Liu, Yanming; Liu, Donglin; Yang, Min; Xie, Kai; Yao, Bo
2017-04-01
A glow discharge plasma generator and diagnostic system has been developed to study the effects of rapidly variable plasmas on electromagnetic wave propagation, mimicking the plasma sheath conditions encountered in space vehicle reentry. The plasma chamber is 400 mm in diameter and 240 mm in length, with a 300-mm-diameter unobstructed clear aperture. Electron densities produced are in the mid 1010 electrons/cm3. An 800 W radio frequency (RF) generator is capacitively coupled through an RF matcher to an internally cooled stainless steel electrode to form the plasma. The RF power is amplitude modulated by a waveform generator that operates at different frequencies. The resulting plasma contains electron density modulations caused by the varying power levels. A 10 GHz microwave horn antenna pair situated on opposite sides of the chamber serves as the source and detector of probe radiation. The microwave power feed to the source horn is split and one portion is sent directly to a high-speed recording oscilloscope. On mixing this with the signal from the pickup horn antenna, the plasma-induced phase shift between the two signals gives the path-integrated electron density with its complete time dependent variation. Care is taken to avoid microwave reflections and extensive shielding is in place to minimize electronic pickup. Data clearly show the low frequency modulation of the electron density as well as higher harmonics and plasma fluctuations.
Casimir amplitudes in topological quantum phase transitions.
Griffith, M A; Continentino, M A
2018-01-01
Topological phase transitions constitute a new class of quantum critical phenomena. They cannot be described within the usual framework of the Landau theory since, in general, the different phases cannot be distinguished by an order parameter, neither can they be related to different symmetries. In most cases, however, one can identify a diverging length at these topological transitions. This allows us to describe them using a scaling approach and to introduce a set of critical exponents that characterize their universality class. Here we consider some relevant models of quantum topological transitions associated with well-defined critical exponents that are related by a quantum hyperscaling relation. We extend to these models a finite-size scaling approach based on techniques for calculating the Casimir force in electromagnetism. This procedure allows us to obtain universal Casimir amplitudes at their quantum critical points. Our results verify the validity of finite-size scaling in these systems and confirm the values of the critical exponents obtained previously.
Effective anisotropy through traveltime and amplitude matching
Wang, Hui
2014-08-05
Introducing anisotropy to seismic wave propagation reveals more realistic physics of our Earth\\'s subsurface as compared to the isotropic assumption. However wavefield modeling, the engine of seismic inverse problems, in anisotropic media still suffers from computational burdens, in particular with complex anisotropy such as transversely isotropic (TI) and Orthorhombic anisotropy. We develop effective isotropic velocity and density models to package the effects of anisotropy such that the wave propagation behavior using these effective models approximate those of the original anisotropic model. We build these effective models through the high frequency asymptotic approximation based on the eikonal and transport equations. We match the geometrical behavior of the wave-fields, given by traveltimes, from the anisotropic and isotropic eikonal equations. This matching yields the effective isotropic velocity that approximates the kinematics of the anisotropic wavefield. Equivalently, we calculate the effective densities by equating the anisotropic and isotropic transport equations. The effective velocities and densities are then fed into the isotropic acoustic variable density wave equation to obtain cheaper anisotropic wavefields. We justify our approach by testing it on an elliptical anisotropic model. The numerical results demonstrate a good matching of both traveltime and amplitude between anisotropic and effective isotropic wavefields.
The pulsed amplitude unit for the SLC
International Nuclear Information System (INIS)
Rolfe, J.; Browne, M.J.; Jobe, R.K.
1987-01-01
There is a recurring requirement in the SLC for the control of devices such as magnets, phase shifters, and attenuators on a beam-by-beam basis. The Pulsed Amplitude Unit (PAU) is a single width CAMAC module developed for this purpose. It provides digitally programmed analog output voltages on a beam-by-beam basis. Up to 32 preprogrammed values of output voltage are available from the single analog output of the module, and any of these values can be associated with any of the 256 possible SLC beam definitions. A 12-bit Analog-to-Digital converter (ADC) digitizes an analog input signal at the appropriate beam time and stores it in a buffer memory. This feature is normally used to monitor the response of the device being controlled by the PAU at each beam time. Initial application of the PAU at is as part of the system that controls the output of Klystorns in the SLC. The PAU combines several different functions in a single module. In order to accommodate these functions in a single width CAMAC module, field programmed logic is used extensively. Field Programmable Logic Arrays, Programmed Array Logic, and a Field Programmable Logic Sequencer are employed
Smyrnis, Nikolaos; Protopapa, Foteini; Tsoukas, Evangelos; Balogh, Allison; Siettos, Constantinos I; Evdokimidis, Ioannis
2014-02-01
This study investigated the question whether spatial working memory related to movement plans (motor working memory) and spatial working memory related to spatial attention and perceptual processes (perceptual spatial working memory) share the same neurophysiological substrate or there is evidence for separate motor and perceptual working memory streams of processing. Towards this aim, ten healthy human subjects performed delayed responses to visual targets presented at different spatial locations. Two tasks were attained, one in which the spatial location of the target was the goal for a pointing movement and one in which the spatial location of the target was used for a perceptual (yes or no) change detection. Each task involved two conditions: a memory condition in which the target remained visible only for the first 250 ms of the delay period and a delay condition in which the target location remained visible throughout the delay period. The amplitude spectrum analysis of the EEG revealed that the alpha (8-12 Hz) band signal was smaller, while the beta (13-30 Hz) and gamma (30-45 Hz) band signals were larger in the memory compared to the non-memory condition. The alpha band signal difference was confined to the frontal midline area; the beta band signal difference extended over the right hemisphere and midline central area, and the gamma band signal difference was confined to the right occipitoparietal area. Importantly, both in beta and gamma bands, we observed a significant increase in the movement-related compared to the perceptual-related memory-specific amplitude spectrum signal in the central midline area. This result provides clear evidence for the dissociation of motor and perceptual spatial working memory.
Energy Technology Data Exchange (ETDEWEB)
Aguilar Benitez de Lugo, M.
1979-07-01
In this work we present several techniques developed for the extraction of the. Transversity amplitudes governing quasi two-body meson baryon reactions with hypercharge exchange. We review the methods used In processes having a pure spin configuration, as well as the more relevant results obtained with data from K{sup p} and Tp interactions at intermediate energies. The predictions of the additive quark model and the ones following from exchange degeneracy and etoxicity are discussed. We present a formalism for amplitude analysis developed for reactions with mixed spin configurations and discuss the methods of parametric estimation of the moduli and phases of.the amplitudes, as well as the various tests employed to check the goodness of the fits. The calculation of the generalized joint density matrices is given and we propose a method based on the generalization of the idea of multipole moments, which allows to investigate the structure of the decay angular correlations and establishes the quality of the fits and the validity of the simplifying assumptions currently used in this type of studies. (Author) 43 refs.
Less Daily Computer Use is Related to Smaller Hippocampal Volumes in Cognitively Intact Elderly.
Silbert, Lisa C; Dodge, Hiroko H; Lahna, David; Promjunyakul, Nutta-On; Austin, Daniel; Mattek, Nora; Erten-Lyons, Deniz; Kaye, Jeffrey A
2016-01-01
Computer use is becoming a common activity in the daily life of older individuals and declines over time in those with mild cognitive impairment (MCI). The relationship between daily computer use (DCU) and imaging markers of neurodegeneration is unknown. The objective of this study was to examine the relationship between average DCU and volumetric markers of neurodegeneration on brain MRI. Cognitively intact volunteers enrolled in the Intelligent Systems for Assessing Aging Change study underwent MRI. Total in-home computer use per day was calculated using mouse movement detection and averaged over a one-month period surrounding the MRI. Spearman's rank order correlation (univariate analysis) and linear regression models (multivariate analysis) examined hippocampal, gray matter (GM), white matter hyperintensity (WMH), and ventricular cerebral spinal fluid (vCSF) volumes in relation to DCU. A voxel-based morphometry analysis identified relationships between regional GM density and DCU. Twenty-seven cognitively intact participants used their computer for 51.3 minutes per day on average. Less DCU was associated with smaller hippocampal volumes (r = 0.48, p = 0.01), but not total GM, WMH, or vCSF volumes. After adjusting for age, education, and gender, less DCU remained associated with smaller hippocampal volume (p = 0.01). Voxel-wise analysis demonstrated that less daily computer use was associated with decreased GM density in the bilateral hippocampi and temporal lobes. Less daily computer use is associated with smaller brain volume in regions that are integral to memory function and known to be involved early with Alzheimer's pathology and conversion to dementia. Continuous monitoring of daily computer use may detect signs of preclinical neurodegeneration in older individuals at risk for dementia.
Polymersomes, smaller than you think: ferrocene as a TEM probe to determine core structure
International Nuclear Information System (INIS)
Johnston, A. H.; Dalton, P. D.; Newman, T. A.
2010-01-01
By incorporating ferrocene into the hydrophobic membrane of PEG-b-PCL polymersome nanoparticles it is possible to selectively visualize their core using Transmission Electron Microscopy (TEM). Two different sizes of ferrocene-loaded polymersomes with mean hydrodynamic diameters of approximately 40 and 90 nm were prepared. Image analysis of TEM pictures of these polymersomes found that the mean diameter of the core was 4-5 times smaller than the mean hydrodynamic diameter. The values obtained also allow the surface diameter and internal volume of the core to be calculated.
Trends and patterns in contemporary management in smaller companies: The Danish perspective
DEFF Research Database (Denmark)
Ulhøi, John Parm; Madsen, Henning
2001-01-01
This paper reports empirical findings from a recent survey of Danish managers with a special focus on managers from smaller companies. The survey has been initiated in Denmark and it is called the 'Danish Management Barometer'. The project is a joint research program between the Aarhus School...... of Business and the Danish Association of Managers and Executives. It is based on a structured, pre-tested questionnaire send out to 1500 pre-notified managers in Denmark aiming at establishing a data base to further monitor and identify interesting changes and patterns within a broad range of managerial...
Scattering amplitudes in four- and six-dimensional gauge theories
International Nuclear Information System (INIS)
Schuster, Theodor
2014-01-01
We study scattering amplitudes in quantum chromodynamics (QCD), N=4 super Yang-Mills (SYM) theory and the six-dimensional N=(1,1) SYM theory, focusing on the symmetries of and relations between the tree-level scattering amplitudes in these three gauge theories. We derive the tree level and one-loop color decomposition of an arbitrary QCD amplitude into primitive amplitudes. Furthermore, we derive identities spanning the null space among the primitive amplitudes. We prove that every color ordered tree amplitude of massless QCD can be obtained from gluon-gluino amplitudes of N=4 SYM theory. Furthermore, we derive analytical formulae for all gluon-gluino amplitudes relevant for QCD. We compare the numerical efficiency and accuracy of evaluating these closed analytic formulae for color ordered QCD tree amplitudes to a numerically efficient implementation of the Berends-Giele recursion. We derive the symmetries of massive tree amplitudes on the coulomb branch of N=4 SYM theory, which in turn can be obtained from N=(1,1) SYM theory by dimensional reduction. Furthermore, we investigate the tree amplitudes of N=(1, 1) SYM theory and explain how analytical formulae can be obtained from a numerical implementation of the supersymmetric BCFW recursion relation and investigate a potential uplift of the massless tree amplitudes of N=4 SYM theory. Finally we study an alternative to dimensional regularization of N=4 SYM theory. The infrared divergences are regulated by masses obtained from a Higgs mechanism. The corresponding string theory set-up suggests that the amplitudes have an exact dual conformal symmetry. We confirm this expectation and illustrate the calculational advantages of the massive regulator by explicit calculations.
Svensson, O; Kvarnemo, C
2003-09-01
Both natural selection and sexual selection may act on nest-building. We tested experimentally how different regimes of egg-predation and male-male competition influence nest-building before mating, using the marine fish sand goby, Pomatoschistus minutus. Males with sneaker males present built the smallest nest-openings, smaller than males held alone or with Pomatoschistus microps males (which may predate eggs and compete over nest-sites but not compete over fertilizations). Males with visual access to other nest-building males tended also to build smaller openings than males held alone or with P. microps. Males with egg-predators present built nests with openings not differing significantly from any other treatment. Our results indicate that the small nest-openings found in the sneaker male treatment are sexually selected through protection against sneaking or by female choice. Across treatments, time span before a male started to build his nest also explained variation in nest-opening width; males starting late built larger nest-openings.
Weekday AOD smaller than weekend AOD in eastern China on the basis of the MODIS AOD product
Song, Jingjing; Xia, Xiangao; Zhang, Xiaoling; Che, Huizheng; Li, Xiaojing
2018-05-01
A weekly cycle of surface particulate matter (PM) characterized by smaller values during weekends and larger values during weekdays was reported in eastern China. Whether column-integrated aerosol optical depth (AOD) showed similar weekly cycling as that of PM was debated. The weekly variation of AOD in eastern China was further studied by using the latest MODIS aerosol product (collection 6) with a fine spatial resolution (0.1°) from 2002 to 2015. We used three statistical methods to determine whether the weekly cycle of AOD was significant. AOD during weekdays (Wednesday to Friday) was lower than that during weekends. The maximum and minimum AOD was generally observed on Monday and Wednesday, respectively. This weekly pattern of AOD was in good agreement with previous results based on satellite aerosol products with a coarse spatial resolution, but it was in contrast to that of PM. Further analysis of the AOD weekly variability in 19 provincial cities suggested that AOD during weekdays was smaller than that during weekends in urban regions. Potential causes for the different weekly cycle of PM and AOD in eastern China were discussed.
International Nuclear Information System (INIS)
Adachi, Michito; Sato, Takamichi; Kawaguchi, Etsuko; Shibata, Akiko
2011-01-01
The aim of this study was to determine whether the brain size of young patients with depressive symptoms is smaller than that of healthy controls using magnetic resonance imaging (MRI). We retrospectively evaluated brain size by calculating the ratio of the brain area to that of the skull (the brain-to-skull ratio) on routine MRI scans including the splenium of the corpus callosum obtained from 19 patients <40 years old with depressive symptoms in 2009. The controls were 12 healthy individuals <40 years old who underwent MRI for medical examinations. The mean brain-to-skull ratio of the control group was 0.850±0.022 (range 0.822-0.889), and that of the patient group was 0.819±0.041 (range 0.756-0.878). An unpaired t-test showed a significant difference in the brain-to-skull ratios between these groups (P=0.011). In particular, in 7 of the 19 patients with longer duration of illness and more severe symptoms, the brain-to-skull ratio was 89%-92% of the mean ratio of the control group. The brain size of young patients with depressive symptoms appears to be smaller than that of healthy controls. (author)
Amplitude growth due to random, correlated kicks
International Nuclear Information System (INIS)
Michelotti, L.; Mills, F.
1989-03-01
Historically, stochastic processes, such as gas scattering or stochastic cooling, have been treated by the Fokker-Planck equation. In this approach, usually considered for one dimension only, the equation can be considered as a continuity equation for a variable which would be a constant of the motion in the absence of the stochastic process, for example, the action variable, I = ε/2π for betatron oscillations, where ε is the area of the Courant-Snyder ellipse, or energy in the case of unbunched beams, or the action variable for phase oscillations in case the beam is bunched. A flux, /Phi/, including diffusive terms can be defined, usually to second order. /Phi/ = M 1 F(I) + M 2 ∂F/∂I + /hor ellipsis/. M 1 and M 2 are the expectation values of δI and (δI) 2 due to the individual stochastic kicks over some period of time, long enough that the variance of these quantities is sufficiently small. Then the Fokker-Planck equation is just ∂F/∂I + ∂/Phi//∂I = 0. In many cases those where the beam distribution has already achieved its final shape, it is sufficient to find the rate of increase of by taking simple averages over the Fokker-Planck equation. At the time this work was begun, there was good knowledge of the second moment for general stochastic processes due to stochastic cooling theory, but the form of the first moment was known only for extremely wideband processes. The purposes of this note are to derive an expression relating the expected single particle amplitude growth to the noise autocorrelation function and to obtain, thereby, the form of M 1 for narrow band processes. 4 refs
Amplitude modulation of atomic wave functions. Final report
Energy Technology Data Exchange (ETDEWEB)
NONE
1998-11-01
The major theoretical advance has been to show that one can modulate Rydberg wave functions using either of two methods: (1) the amplitude modulation technique which depends on autoionization to deplete part of the wave function, or (2) a phase modulation method, which uses a change in the core potential to create a localized phase shift in the wave function. Essentially, these two methods can both be seen as using the core potential to change the Rydberg wave function, using the imaginary part of the potential to do amplitude modulation, or using the real part of the potential to do phase modulation. This work will be published as the authors acquire experimental results which show the differences between the two methods. One of the results of this theoretical study is that the initial proposal to study Barium 6snd states had a significant flaw. Neither the autoionization time, nor the quantum defect shifts are very large in these cases. This means that the modulation is relatively small. This shows itself primarily in the difficulty of seeing significant population redistribution into different 6snd states. The authors intend to correct this in the next funding cycle either: (a) by using the more quickly decaying Ba 6pnf states to modulate 6snd states, or (b) by using Sr 5 snd states, as outlined in this report. Their first, low power experiments are complete. These experiments have used two pulses to do a temporal version of the Ramsey separated oscillatory fields excitation. The two pulses are generated by passing the single pulse through a Michelson-Morley interferometer, which is computer controlled to sweep one arm through 2.5 {micro}m in steps of 10 nm. The second pulse`s excitation interferes with that of the first pulse, and so the total excitation has a sinusoidal variation (with a time period equal to the optical period) on top of a constant background. The amplitude of the total variation should decay at half of the rate decay rate of the autoionizing
Probabilistic Amplitude Shaping With Hard Decision Decoding and Staircase Codes
Sheikh, Alireza; Amat, Alexandre Graell i.; Liva, Gianluigi; Steiner, Fabian
2018-05-01
We consider probabilistic amplitude shaping (PAS) as a means of increasing the spectral efficiency of fiber-optic communication systems. In contrast to previous works in the literature, we consider probabilistic shaping with hard decision decoding (HDD). In particular, we apply the PAS recently introduced by B\\"ocherer \\emph{et al.} to a coded modulation (CM) scheme with bit-wise HDD that uses a staircase code as the forward error correction code. We show that the CM scheme with PAS and staircase codes yields significant gains in spectral efficiency with respect to the baseline scheme using a staircase code and a standard constellation with uniformly distributed signal points. Using a single staircase code, the proposed scheme achieves performance within $0.57$--$1.44$ dB of the corresponding achievable information rate for a wide range of spectral efficiencies.
Does Fundus Fluorescein Angiography Procedure Affect Ocular Pulse Amplitude?
Directory of Open Access Journals (Sweden)
Gökhan Pekel
2013-01-01
Full Text Available Purpose. This study examines the effects of fundus fluorescein angiography (FFA procedure on ocular pulse amplitude (OPA and intraocular pressure (IOP. Materials and Methods. Sixty eyes of 30 nonproliferative diabetic retinopathy patients (15 males, 15 females were included in this cross-sectional case series. IOP and OPA were measured with the Pascal dynamic contour tonometer before and after 5 minutes of intravenous fluorescein dye injection. Results. Pre-FFA mean OPA value was mmHg and post-FFA mean OPA value was mmHg (. Pre-FFA mean IOP value was mmHg and post-FFA mean IOP value was mmHg (. Conclusion. Although both mean OPA and IOP values were decreased after FFA procedure, the difference was not statistically significant. This clinical trial is registered with Australian New Zealand Clinical Trials Registry number ACTRN12613000433707.
Phonological awareness and sinusoidal amplitude modulation in phonological dislexia.
Peñaloza-López, Yolanda; Herrera-Rangel, Aline; Pérez-Ruiz, Santiago J; Poblano, Adrián
2016-04-01
Dyslexia is the difficulty of children in learning to read and write as results of neurological deficiencies. The objective was to test the Phonological awareness (PA) and Sinusoidal amplitude modulation (SAM) threshold in children with Phonological dyslexia (PD). We performed a case-control, analytic, cross sectional study. We studied 14 children with PD and 14 control children from 7 to 11 years of age, by means of PA measurement and by SAM test. The mean age of dyslexic children was 8.39 years and in the control group was 8.15. Children with PD exhibited inadequate skills in PA, and SAM. We found significant correlations between PA and SAM at 4 Hertz frequency, and calculated regression equations that predicts between one-fourth and one-third of variance of measurements. Alterations in PA and SAM found can help to explain basis of deficient language processing exhibited by children with PD.
van der Hoeven, Niels V; Lodestijn, Sophie; Nanninga, Stephanie; van Montfrans, Gert A; van den Born, Bert-Jan H
2013-11-01
There are currently few recommendations on how to assess inter-arm blood pressure (BP) differences. The authors compared simultaneous with sequential measurement on mean BP, inter-arm BP differences, and within-visit reproducibility in 240 patients stratified according to age (simultaneous and three sequential BP measurements were taken in each patient. Starting measurement type and starting arm for sequential measurements were randomized. Mean BP and inter-arm BP differences of the first pair and reproducibility of inter-arm BP differences of the first and second pair were compared between both methods. Mean systolic BP was 1.3±7.5 mm Hg lower during sequential compared with simultaneous measurement (Psequential measurement was on average higher than the second, suggesting an order effect. Absolute systolic inter-arm BP differences were smaller on simultaneous (6.2±6.7/3.3±3.5 mm Hg) compared with sequential BP measurement (7.8±7.3/4.6±5.6 mm Hg, PSimultaneous measurement of BP at both arms reduces order effects and results in smaller inter-arm BP differences, thereby potentially reducing unnecessary referral and diagnostic procedures. ©2013 Wiley Periodicals, Inc.
Stawski, Robert S; Almeida, David M; Lachman, Margie E; Tun, Patricia A; Rosnick, Christopher B
2010-06-01
The authors of this study investigated whether fluid cognitive ability predicts exposure and emotional reactivity to daily stressors. A national sample of adults from the Midlife in the United States study and the National Study of Daily Experiences (N = 1,202) who had a mean age of 57 years (SD = 12; 56% women, 44% men) completed positive and negative mood reports as well as a stressor diary on 8 consecutive evenings via telephone. Participants also completed a telephone-based battery of tests measuring fluid cognitive ability. Higher levels of fluid cognitive ability were associated with greater exposure to work- and home-related overload stressors. Possessing higher levels of fluid cognitive ability was associated with smaller stressor-related increases in negative mood, primarily for interpersonal tensions and network stressors, and smaller stressor-related decreases in positive mood for interpersonal tensions. Furthermore, fluid cognitive ability was unrelated to subjective severity ratings of the stressors reported. Discussion focuses on the role of fluid cognitive ability in daily stress processes. (c) 2010 APA, all rights reserved).
Order of Magnitude Smaller Limit on the Electron's Electron Dipole Moment
Gabrielse, Gerald
2014-05-01
Proposed extensions to the Standard Model of particle physics typically predict that the electron would naturally have a small but potentially measurable electric dipole moment (EDM). The Standard Model, known to be incomplete, instead predicts that the electron EDM is much too small to measure. The ACME collaboration used the enormous electric field that electrons experience within a ThO molecule, the unique structure of this molecule, and a cryogenic buffer gas beam of molecules to search for an electron EDM. The new search was sensitive enough to detect an EDM that is ten times smaller than the previously measured upper limit - well within the range of predictions from various proposed extensions to the Standard Model. We did not detect such an EDM, however. Instead, we set a new upper limit on the electron EDM at a 90% confidence limit, | de | < 8 . 7 × 10-29 , making use of the effective electric field calculated for ThO. The new limit stringently constrains the parameters of proposed extensions to the Standard Model to values that predict an electron EDM smaller than the new limit. The TeV energy scale being probed is comparable to that being investigated at CERN's Large Hadron Collider (LHC). Supported by the AMO program of the NSF.
Use of precracked Charpy and smaller specimens to establish the master curve
International Nuclear Information System (INIS)
Sokolov, M.A.; McCabe, D.E.; Nanstad, R.K.; Davidov, Y.A.
1997-01-01
The current provisions used in the U.S. Code of Federal Regulations for the determination of the fracture toughness of reactor pressure vessel steels employs an assumption that there is a direct correlation between K Ic lower-bound toughness and the Charpy V-notch transition curve. Such correlations are subject to scatter from both approaches which weakens the reliability of fracture mechanics-based analyses. In this study, precracked Charpy and smaller size specimens are used in three-point static bend testing to develop fracture mechanics based K k values. The testing is performed under carefully controlled conditions such that the values can be used to predict the fracture toughness performance of large specimens. The concept of a universal transition curve (master curve) is applied. Data scatter that is characteristic of commercial grade steels and their weldments is handled by Weibull statistical modeling. The master curve is developed to describe the median K Jc fracture toughness for 1T size compact specimens. Size effects are modeled using weakest-link theory and are studied for different specimen geometries. It is shown that precracked Charpy specimens when tested within their confined validity limits follow the weakest-link size-adjustment trend and predict the fracture toughness of larger specimens. Specimens of smaller than Charpy sizes (5 mm thick) exhibit some disparities in results relative to weakest-link size adjustment prediction suggesting that application of such adjustment to very small specimens may have some limitations
Nehme, Ziad; Boyle, Malcolm J
2009-02-20
Suboptimal bag ventilation in cardiopulmonary resuscitation (CPR) has demonstrated detrimental physiological outcomes for cardiac arrest patients. In light of recent guideline changes for resuscitation, there is a need to identify the efficacy of bag ventilation by prehospital care providers. The objective of this study was to evaluate bag ventilation in relation to operator ability to achieve guideline consistent ventilation rate, tidal volume and minute volume when using two different capacity self-inflating bags in an undergraduate paramedic cohort. An experimental study using a mechanical lung model and a simulated adult cardiac arrest to assess the ventilation ability of third year Monash University undergraduate paramedic students. Participants were instructed to ventilate using 1600 ml and 1000 ml bags for a length of two minutes at the correct rate and tidal volume for a patient undergoing CPR with an advanced airway. Ventilation rate and tidal volume were recorded using an analogue scale with mean values calculated. Ethics approval was granted. Suboptimal ventilation with the use of conventional 1600 ml bag was common, with 77% and 97% of participants unable to achieve guideline consistent ventilation rates and tidal volumes respectively. Reduced levels of suboptimal ventilation arouse from the use of the smaller bag with a 27% reduction in suboptimal tidal volumes (p = 0.015) and 23% reduction in suboptimal minute volumes (p = 0.045). Smaller self-inflating bags reduce the incidence of suboptimal tidal volumes and minute volumes and produce greater guideline consistent results for cardiac arrest patients.
A nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle.
van Bolhuis, A I; Holsheimer, J; Savelberg, H H
2001-05-30
Electrical stimulation of peripheral nerve results in a motor-unit recruitment order opposite to that attained by natural neural control, i.e. from large, fast-fatiguing to progressively smaller, fatigue-resistant motor-units. Yet animal studies involving physiological exercise protocols of low intensity and long duration require minimal fatigue. The present study sought to apply a nerve stimulation method to selectively recruit smaller motor-units in rat skeletal muscle. Two pulse generators were used, independently supplying short supramaximal cathodal stimulating pulses (0.5 ms) and long subthreshold cathodal inactivating pulses (1.5 s) to the sciatic nerve. Propagation of action potentials was selectively blocked in nerve fibres of different diameter by adjusting the strength of the inactivating current. A tensile-testing machine was used to gauge isometric muscle force of the plantaris and both heads of the gastrocnemius muscle. The order of motor-unit recruitment was estimated from twitch characteristics, i.e. peak force and relaxation time. The results showed prolonged relaxation at lower twitch peak forces as the intensity of the inactivating current increased, indicating a reduction of the number of large motor-units to force production. It is shown that the nerve stimulation method described is effective in mimicking physiological muscle control.
Energy Technology Data Exchange (ETDEWEB)
Saeki, T [Japan National Oil Corp., Tokyo (Japan). Technology Research Center
1997-10-22
Discussions were given on seismic exploration from the ground surface using the reflection method, for surface consistent amplitude correction from among effects imposed from the ground surface and a surface layer. Amplitude distribution on the reflection wave zone is complex. Therefore, items to be considered in making an analysis are multiple, such as estimation of spherical surface divergence effect and exponential attenuation effect, not only amplitude change through the surface layer. If all of these items are taken into consideration, burden of the work becomes excessive. As a method to solve this problem, utilization of amplitude in initial movement of a diffraction wave may be conceived. Distribution of the amplitude in initial movement of the diffraction wave shows a value relatively close to distribution of the vibration transmitting and receiving points. The reason for this is thought because characteristics of the vibration transmitting and receiving points related with waveline paths in the vicinity of the ground surface have no great difference both on the diffraction waves and on the reflection waves. The lecture described in this paper introduces an attempt of improving the efficiency of the surface consistent amplitude correction by utilizing the analysis of amplitude in initial movement of the diffraction wave. 4 refs., 2 figs.
Energy Technology Data Exchange (ETDEWEB)
Navelet-Noualhier, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1967-06-15
Helicity amplitudes are expressed via the spinor amplitudes in terms of the Joos invariant which have been shown by Williams to be free from kinematical singularities. This procedure allows to analyze the kinematical singularities of helicity amplitudes and separate them out, which results into the definition of regularized helicity amplitudes. A crossing matrix for helicity amplitudes, is written down, corresponding to the continuation path used to cross spinor amplitudes. We verify explicitly that the corresponding crossing matrix for regularized helicity amplitudes is uniform as it should be. Kinematical constraints which generalize, to the case of arbitrary spins and masses, relations which must hold between helicity amplitudes at some values of the energy variable in {pi}N {yields} {pi}N, {pi}{pi} {yields} NN-bar and NN-bar {yields} NN-bar reactions, appear as a consequence of the existence of poles in the crossing matrix between regularized helicity amplitudes. An english version of this work has been written with G. Cohen-Tannoudji and A. Morel and submitted for publication to Annals of Physics. (author) [French] Les amplitudes d'helicite pour une reaction a deux corps sont exprimees, par l'intermediaire des amplitudes spinorielles, en fonction d'amplitudes invariantes de Joos qui sont, comme l'a montre Williams, sans singularites cinematiques. Ce procede nous permet d'analyser puis d'eliminer les singularites cinematiques des amplitudes d'helicite. Ceci nous conduit a la definition d'amplitudes d'helicite 'regularisees'. Une relation de 'croisement' entre amplitudes d'helicite est ecrite; elle realise leur prolongement analytique le long du chemin utilise pour 'croiser' les amplitudes spinorielles. Nous verifions que les elements de la matrice de croisement entre amplitudes d'helicite 'regularisees' sont bien uniformes. Les contraintes cinematiques qui generalisent, au cas de masses et de spins arbitraires, les relations obtenues dans les reactions {pi
Eikonal representation of N-body Coulomb scattering amplitudes
International Nuclear Information System (INIS)
Fried, H.M.; Kang, K.; McKellar, B.H.J.
1983-01-01
A new technique for the construction of N-body Coulomb scattering amplitudes is proposed, suggested by the simplest case of N = 2: Calculate the scattering amplitude in eikonal approximation, discard the infinite phase factors which appear upon taking the limit of a Coulomb potential, and treat the remainder as an amplitude whose absolute value squared produces the exact, Coulomb differential cross section. The method easily generalizes to the N-body Coulomb problem for elastic scattering, and for inelastic rearrangement scattering of Coulomb bound states. We give explicit results for N = 3 and 4; in the N = 3 case we extract amplitudes for the processes (12)+3->1+2+3 (breakup), (12)+3->1+(23) (rearrangement), and (12)+3→(12)'+3 (inelastic scattering) as residues at the appropriate poles in the free-free amplitude. The method produces scattering amplitudes f/sub N/ given in terms of explicit quadratures over (N-2) 2 distinct integrands
Expansion of all multitrace tree level EYM amplitudes
Du, Yi-Jian; Feng, Bo; Teng, Fei
2017-12-01
In this paper, we investigate the expansion of tree level multitrace Einstein-Yang-Mills (EYM) amplitudes. First, we propose two types of recursive expansions of tree level EYM amplitudes with an arbitrary number of gluons, gravitons and traces by those amplitudes with fewer traces or/and gravitons. Then we give many support evidence, including proofs using the Cachazo-He-Yuan (CHY) formula and Britto-Cachazo-Feng-Witten (BCFW) recursive relation. As a byproduct, two types of generalized BCJ relations for multitrace EYM are further proposed, which will be useful in the BCFW proof. After one applies the recursive expansions repeatedly, any multitrace EYM amplitudes can be given in the Kleiss-Kuijf (KK) basis of tree level color ordered Yang-Mills (YM) amplitudes. Thus the Bern-Carrasco-Johansson (BCJ) numerators, as the expansion coefficients, for all multitrace EYM amplitudes are naturally constructed.
Tensor exchange amplitudes in K +- N charge exchange reactions
International Nuclear Information System (INIS)
Svec, M.
1979-01-01
Tensor (A 2 ) exchange amplitudes in K +- N charge exchange (CEX) are constructed from the K +- N CEX data supplemented by information on the vector (rho) exchange amplitudes from πN sca tering. We observed new features in the t-structure of A 2 exchange amplitudes which contradict the t-de pendence anticipated by most of the Regge models. The results also provide evidence for violation of weak exchange degeneracy
Loop Amplitudes in Pure Yang-Mills from Generalised Unitarity
Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele
2005-01-01
We show how generalised unitarity cuts in D = 4 - 2 epsilon dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.
Loop amplitudes in pure Yang-Mills from generalised unitarity
International Nuclear Information System (INIS)
Brandhuber, Andreas; McNamara, Simon; Spence, Bill; Travaglini, Gabriele
2005-01-01
We show how generalised unitarity cuts in D = 4-2ε dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions
Loop amplitudes in pure Yang-Mills from generalised unitarity
Energy Technology Data Exchange (ETDEWEB)
Brandhuber, Andreas [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); McNamara, Simon [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Spence, Bill [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom); Travaglini, Gabriele [Department of Physics, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom)
2005-10-15
We show how generalised unitarity cuts in D = 4-2{epsilon} dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational terms in the amplitudes, as well as the cut-constructible parts. We test the validity of our method by re-deriving the one-loop ++++, -+++, --++, -+-+ and +++++ gluon scattering amplitudes using generalised quadruple cuts and triple cuts in D dimensions.
Calculation and modular properties of multiloop superstring amplitudes
International Nuclear Information System (INIS)
Danilov, G. S.
2013-01-01
Multiloop superstring amplitudes are calculated within an extensively used gauge where the two-dimensional gravitino field carries Grassmann moduli. In general, the amplitudes possess, instead of modular symmetry, symmetry with respect to modular transformation supplemented with appropriate transformations of two-dimensional local supersymmetry. If the number of loops is larger than three, the integrationmeasures are notmodular forms, while the expression for the amplitude contains integrals along the boundary of the fundamental region of the modular group.
Efficient analytic computation of higher-order QCD amplitudes
International Nuclear Information System (INIS)
Bern, Z.; Chalmers, G.; Dunbar, D.C.; Kosower, D.A.
1995-01-01
The authors review techniques simplifying the analytic calculation of one-loop QCD amplitudes with many external legs, for use in next-to-leading-order corrections to multi-jet processes. Particularly useful are the constraints imposed by perturbative unitarity, collinear singularities and a supersymmetry-inspired organization of helicity amplitudes. Certain sequences of one-loop helicity amplitudes with an arbitrary number of external gluons have been obtained using these constraints
Improved pion pion scattering amplitude from dispersion relation formalism
International Nuclear Information System (INIS)
Cavalcante, I.P.; Coutinho, Y.A.; Borges, J. Sa
2005-01-01
Pion-pion scattering amplitude is obtained from Chiral Perturbation Theory at one- and two-loop approximations. Dispersion relation formalism provides a more economic method, which was proved to reproduce the analytical structure of that amplitude at both approximation levels. This work extends the use of the formalism in order to compute further unitarity corrections to partial waves, including the D-wave amplitude. (author)
Ambitwistor strings and reggeon amplitudes in N=4 SYM
Directory of Open Access Journals (Sweden)
L.V. Bork
2017-11-01
Full Text Available We consider the description of reggeon amplitudes (Wilson lines form factors in N=4 SYM within the framework of four dimensional ambitwistor string theory. The latter is used to derive scattering equations representation for reggeon amplitudes with multiple reggeized gluons present. It is shown, that corresponding tree-level string correlation function correctly reproduces previously obtained Grassmannian integral representation of reggeon amplitudes in N=4 SYM.
The five-gluon amplitude and one-loop integrals
International Nuclear Information System (INIS)
Bern, Z.; Dixon, L.; Kosower, D.A.
1992-12-01
We review the conventional field theory description of the string motivated technique. This technique is applied to the one-loop five-gluon amplitude. To evaluate the amplitude a general method for computing dimensionally regulated one-loop integrals is outlined including results for one-loop integrals required for the pentagon diagram and beyond. Finally, two five-gluon helicity amplitudes are given
Renormalization in the complete Mellin representation of Feynman amplitudes
International Nuclear Information System (INIS)
Calan, C. de; David, F.; Rivasseau, V.
1981-01-01
The Feynmann amplitudes are renormalized in the formalism of the CM representation. This Mellin-Barnes type integral representation, previously introduced for the study of asymptotic behaviours, is shown to have the following interesting property: in contrast with the usual subtraction procedures, the renormalization leaves the CM intergrand unchanged, and only results into translations of the integration path. The explicit CM representation of the renormalized amplitudes is given. In addition, the dimensional regularization and the extension to spinor amplitudes are sketched. (orig.)
Directory of Open Access Journals (Sweden)
Nathalie Mella
2018-02-01
Full Text Available It is well known that cognitive decline in older adults is of smaller amplitude in longitudinal than in cross-sectional studies. Yet, the measure of interest rests generally with aggregated group data. A focus on individual developmental trajectories is rare, mainly because it is difficult to assess intraindividual change reliably. Individual differences in developmental trajectories may differ quantitatively (e.g., larger or smaller decline or qualitatively (e.g., decline vs improvement, as well as in the degree of heterogeneity of change across different cognitive domains or different tasks. The present paper aims at exploring, within the Geneva Variability Study, individual change across several cognitive domains in 92 older adults (aged 59–89 years at baseline over a maximum of seven years and a half. Two novel, complementary methods were used to explore change in cognitive performance while remaining entirely at the intra-individual level. A bootstrap based confidence interval was estimated, for each participant and for each experimental condition, making it possible to define three patterns: stability, increase or decrease in performance. Within-person ANOVAs were also conducted for each individual on all the tasks. Those two methods allowed quantifying the direction, the amplitude and the heterogeneity of change for each individual. Results show that trajectories differed widely among individuals and that decline is far from being the rule.
Algebraic evaluation of rational polynomials in one-loop amplitudes
International Nuclear Information System (INIS)
Binoth, Thomas; Guillet, Jean-Philippe; Heinrich, Gudrun
2007-01-01
One-loop amplitudes are to a large extent determined by their unitarity cuts in four dimensions. We show that the remaining rational terms can be obtained from the ultraviolet behaviour of the amplitude, and determine universal form factors for these rational parts by applying reduction techniques to the Feynman diagrammatic representation of the amplitude. The method is valid for massless and massive internal particles. We illustrate this method by evaluating the rational terms of the one-loop amplitudes for gg→H, γγ→γγ, gg→gg,γγ→ggg and γγ→γγγγ
Phase and amplitude control system for Stanford Linear Accelerator
International Nuclear Information System (INIS)
Yoo, S.J.
1983-01-01
The computer controlled phase and amplitude detection system measures the instantaneous phase and amplitude of a 1 micro-second 2856 MHz rf pulse at a 180 Hz rate. This will be used for phase feedback control, and also for phase and amplitude jitter measurement. The program, which was originally written by John Fox and Keith Jobe, has been modified to improve the function of the system. The software algorithms used in the measurement are described, as is the performance of the prototype phase and amplitude detector system
New rigorous asymptotic theorems for inverse scattering amplitudes
International Nuclear Information System (INIS)
Lomsadze, Sh.Yu.; Lomsadze, Yu.M.
1984-01-01
The rigorous asymptotic theorems both of integral and local types obtained earlier and establishing logarithmic and in some cases even power correlations aetdeen the real and imaginary parts of scattering amplitudes Fsub(+-) are extended to the inverse amplitudes 1/Fsub(+-). One also succeeds in establishing power correlations of a new type between the real and imaginary parts, both for the amplitudes themselves and for the inverse ones. All the obtained assertions are convenient to be tested in high energy experiments when the amplitudes show asymptotic behaviour
Proof of the fundamental BCJ relations for QCD amplitudes
International Nuclear Information System (INIS)
Cruz, Leonardo de la; Kniss, Alexander; Weinzierl, Stefan
2015-01-01
The fundamental BCJ-relation is a linear relation between primitive tree amplitudes with different cyclic orderings. The cyclic orderings differ by the insertion place of one gluon. The coefficients of the fundamental BCJ-relation are linear in the Lorentz invariants 2p_ip_j. The BCJ-relations are well established for pure gluonic amplitudes as well as for amplitudes in N=4 super-Yang-Mills theory. Recently, it has been conjectured that the BCJ-relations hold also for QCD amplitudes. In this paper we give a proof of this conjecture. The proof is valid for massless and massive quarks.
Amplitude dependent damping in single crystalline high purity molybdenum
International Nuclear Information System (INIS)
Zelada-Lambri, G.I; Lambri, O.A; Garcia, J.A; Lomer, J.N
2004-01-01
Amplitude dependent damping measurements were performed on high purity single crystalline molybdenum at several different constant temperatures between room temperature and 1273K. The employed samples were single crystals with the orientation, having a residual resistivity ratio of about 8000. Previously to the amplitude dependent damping tests, the samples were subjected to different thermomechanical histories. Amplitude dependent damping effects appear only during the first heating run in temperature where the samples have the thermomechanical state of the deformation process at room temperature. In the subsequent run-ups in temperature, i.e, after subsequent annealings, amplitude dependent damping effects were not detected (au)
Analytical structure of the 3. -->. 3 forward scattering amplitude
Energy Technology Data Exchange (ETDEWEB)
Logunov, A A; Medvedev, B V; Muzafarov, L M; Pavlov, V P; Polivanov, M K; Sukhanov, A D [AN SSSR, Moscow. Matematicheskij Inst.
1979-08-01
Analytical properties of the amplitude of 3..-->..3 forward scattering established in the framework of the Bogolyubov axiomatic approach are described. The amplitudes of the different channels of the process are boundary values of a unique analytical function of invariant variables. Crossing-symmetry property of the amplitude is proved. Analysis of the absorptive part of the amplitude is performed and the generalized optical theorem is proved which connects one of the contributions into the absorptive part with the distribution function of the inclusive process.
Generalized unitarity for N=4 super-amplitudes
Energy Technology Data Exchange (ETDEWEB)
Drummond, J.M.; Henn, J. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France); Korchemsky, G.P., E-mail: Gregory.Korchemsky@cea.fr [Institut de Physique Théorique, CEA Saclay, 91191 Gif-sur-Yvette Cedex (France); Sokatchev, E. [LAPTH, Université de Savoie, CNRS B.P. 110, F-74941 Annecy-le-Vieux Cedex (France)
2013-04-21
We develop a manifestly supersymmetric version of the generalized unitarity cut method for calculating scattering amplitudes in N=4 SYM theory. We illustrate the power of this method by computing the one-loop n-point NMHV super-amplitudes. The result confirms two conjectures which we made in Drummond, et al., [1]. Firstly, we derive the compact, manifestly dual superconformally covariant form of the NMHV tree amplitudes for arbitrary number and types of external particles. Secondly, we show that the ratio of the one-loop NMHV to the MHV amplitude is dual conformal invariant.
Tree-level amplitudes and dual superconformal symmetry
Energy Technology Data Exchange (ETDEWEB)
Drummond, J M, E-mail: drummond@lapp.in2p3.fr [PH-TH Division, CERN, CH-1211, Geneva 23 (Switzerland); LAPTH, Universite de Savoie, CNRS, B.P. 110, F-74941 Annecy-le-Vieux Cedex (France)
2011-11-11
We review the structure of gauge theory scattering amplitudes at tree level and describe how a compact expression can be found which encodes all the tree-level amplitudes in the maximally supersymmetric N=4 theory. The expressions for the amplitudes reveal a dual superconformal symmetry. We describe how these ideas can be extended to leading singularities and the loop integrand in the planar theory and discuss the appearance of dual conformal symmetry in higher-dimensional gauge theories. This paper is an invited review for a special issue of Journal of Physics A: Mathematical and Theoretical devoted to 'Scattering amplitudes in gauge theories'. (review)
New relations for Einstein–Yang–Mills amplitudes
International Nuclear Information System (INIS)
Stieberger, Stephan; Taylor, Tomasz R.
2016-01-01
We obtain new relations between Einstein–Yang–Mills (EYM) amplitudes involving N gauge bosons plus a single graviton and pure Yang–Mills amplitudes involving N gauge bosons plus one additional vector boson inserted in a way typical for a gauge boson of a “spectator” group commuting with the group associated to original N gauge bosons. We show that such EYM amplitudes satisfy U(1) decoupling relations similar to Kleiss–Kuijf relations for Yang–Mills amplitudes. We consider a D-brane embedding of EYM amplitudes in the framework of disk amplitudes involving open and closed strings. A new set of monodromy relations is derived for mixed open–closed amplitudes with one closed string inserted on the disk world-sheet and a number of open strings at the boundary. These relations allow expressing the latter in terms of pure open string amplitudes and, in the field-theory limit, they yield the U(1) decoupling relations for EYM amplitudes.
Directory of Open Access Journals (Sweden)
Steven R. Randall
2017-11-01
Full Text Available Sub-Saharan Africa is home to 90% of HIV infected (HIV+ children. Since the advent of antiretroviral therapy (ART, HIV/AIDS has transitioned to a chronic condition where central nervous system (CNS damage may be ongoing. Although, most guidelines recommend early ART to reduce CNS viral reservoirs, the brain may be more vulnerable to potential neurotoxic effects of ART during the rapid development phase in the first years of life. Here we investigate differences in subcortical volumes between 5-year-old HIV+ children who received early ART (before age 18 months and uninfected children using manual tracing of Magnetic Resonance Images. Participants included 61 Xhosa children (43 HIV+/18 uninfected, mean age = 5.4 ± 0.3 years, 25 male from the children with HIV early antiretroviral (CHER trial; 27 children initiated ART before 12 weeks of age (ART-Before12Wks and 16 after 12 weeks (ART-After12Wks. Structural images were acquired on a 3T Allegra MRI in Cape Town and manually traced using MultiTracer. Volumetric group differences (HIV+ vs. uninfected; ART-Before12Wks vs. ART-After12Wks were examined for the caudate, nucleus accumbens (NA, putamen (Pu, globus pallidus (GP, and corpus callosum (CC, as well as associations within infected children of structure volumes with age at ART initiation and CD4/CD8 as a proxy for immune health. HIV+ children had significantly larger NA and Pu volumes bilaterally and left GP volumes than controls, whilst CC was smaller. Bilateral Pu was larger in both treatment groups compared to controls, while left GP and bilateral NA were enlarged only in ART-After12Wks children. CC was smaller in both treatment groups compared to controls, and smaller in ART-After12Wks compared to ART-Before12Wks. Within infected children, delayed ART initiation was associated with larger Pu volumes, effects that remained significant when controlling for sex and duration of treatment interruption (left β = 0.447, p = 0.005; right β = 0
Akbulut, Fatih; Kucuktopcu, Onur; Kandemir, Emre; Sonmezay, Erkan; Simsek, Abdulmuttalip; Ozgor, Faruk; Binbay, Murat; Muslumanoglu, Ahmet Yaser; Gurbuz, Gokhan
2016-01-01
To compare the outcomes of flexible ureterorenoscopy (F-URS) and mini-percutaneous nephrolithotomy (mini-PNL) in the treatment of lower calyceal stones smaller than 2 cm. Patients who underwent F-URS and mini-PNL for the treatment of lower calyceal stones smaller than 2 cm between March 2009 and December 2014 were retrospectively evaluated. Ninety-four patients were divided into two groups by treatment modality: F-URS (Group 1: 63 patients) and mini-PNL (Group 2: 31 patients). All patients were preoperatively diagnosed with intravenous pyelography or computed tomography. Success rates for F-URS and mini-PNL at postoperative first month were 85.7% and 90.3%, respectively. Operation time, fluoroscopy time, and hospitalization time for F-URS and mini-PNL patients were 44.40 min, 2.9 min, 22.4 h, and 91.9 min, 6.4 min, and 63.8 h, respectively. All three parameters were significantly shorter among the F-URS group (p PNL group (0.39 mg/dL vs. 1.15 mg/dL, p = 0.001). A comparison of complications according to the Clavien classification demonstrated significant differences between the groups (p = 0.001). More patients in the F-URS groups require antibiotics due to urinary tract infection, and more patients in the mini-PNL group required ureteral double J catheter insertion under general anesthesia. Although both F-URS and mini-PNL have similar success rates for the treatment of lower calyceal stones, F-URS appears to be more favorable due to shorter fluoroscopy and hospitalization times; and lower hemoglobin drops. Multicenter and studies using higher patient volumes are needed to confirm these findings.
Tsunami Amplitude Estimation from Real-Time GNSS.
Jeffries, C.; MacInnes, B. T.; Melbourne, T. I.
2017-12-01
Tsunami early warning systems currently comprise modeling of observations from the global seismic network, deep-ocean DART buoys, and a global distribution of tide gauges. While these tools work well for tsunamis traveling teleseismic distances, saturation of seismic magnitude estimation in the near field can result in significant underestimation of tsunami excitation for local warning. Moreover, DART buoy and tide gauge observations cannot be used to rectify the underestimation in the available time, typically 10-20 minutes, before local runup occurs. Real-time GNSS measurements of coseismic offsets may be used to estimate finite faulting within 1-2 minutes and, in turn, tsunami excitation for local warning purposes. We describe here a tsunami amplitude estimation algorithm; implemented for the Cascadia subduction zone, that uses continuous GNSS position streams to estimate finite faulting. The system is based on a time-domain convolution of fault slip that uses a pre-computed catalog of hydrodynamic Green's functions generated with the GeoClaw shallow-water wave simulation software and maps seismic slip along each section of the fault to points located off the Cascadia coast in 20m of water depth and relies on the principle of the linearity in tsunami wave propagation. The system draws continuous slip estimates from a message broker, convolves the slip with appropriate Green's functions which are then superimposed to produce wave amplitude at each coastal location. The maximum amplitude and its arrival time are then passed into a database for subsequent monitoring and display. We plan on testing this system using a suite of synthetic earthquakes calculated for Cascadia whose ground motions are simulated at 500 existing Cascadia GPS sites, as well as real earthquakes for which we have continuous GNSS time series and surveyed runup heights, including Maule, Chile 2010 and Tohoku, Japan 2011. This system has been implemented in the CWU Geodesy Lab for the Cascadia
Riis, J
2014-07-01
This paper uses the frameworks and evidence from marketing and behavioral economics to highlight the opportunities and barriers for portion control in food service environments. Applying Kahneman's 'thinking fast and slow' concepts, it describes 10 strategies that can be effective in 'tricking' the consumer's fast cognitive system to make better decisions and in triggering the slow cognitive system to help prevent the fast system from making bad decisions. These strategies include shrinking defaults, elongating packages, increasing the visibility of small portions, offering more mixed virtue options, adding more small sizes, offering 'right-sized' standard portions, using meaningful size labels, adopting linear pricing, using temporal landmarks to push smaller portions and facilitating pre-commitment. For each of these strategies, I discuss the specific cost and revenue barriers that a food service operator would face if the strategy were adopted.
Benefits of research activities incorporation into the core business of smaller TSOs
International Nuclear Information System (INIS)
Rovny, J.
2007-01-01
Much has been done to develop the nuclear safety technology to the current level. Nevertheless, incremental development of this knowledge based on demand-pull innovation only seems not to satisfy the future needs of nuclear industry. In order to cope with technical challenges faced by TSOs in the context of nuclear renaissance, the technology-push innovation has to be done in certain amount as well to ensure that brand-new ideas, technologies and attitudes will be implemented in order to enhance nuclear safety. For the reasons described, the technology-push innovation is accessible mainly for larger organizations. In order to cross the entrance barrier for smaller organizations, a cooperation among several TSOs is needed. Uncertainties related to investments in research can be optimalized by creating a research project portfolio. According to the traditional innovation management theory, technological innovation is a driver of competition and profitability and, therefore, the motivation is supported by economical benefits. (author)
Riis, J
2014-01-01
This paper uses the frameworks and evidence from marketing and behavioral economics to highlight the opportunities and barriers for portion control in food service environments. Applying Kahneman's ‘thinking fast and slow' concepts, it describes 10 strategies that can be effective in ‘tricking' the consumer's fast cognitive system to make better decisions and in triggering the slow cognitive system to help prevent the fast system from making bad decisions. These strategies include shrinking defaults, elongating packages, increasing the visibility of small portions, offering more mixed virtue options, adding more small sizes, offering ‘right-sized' standard portions, using meaningful size labels, adopting linear pricing, using temporal landmarks to push smaller portions and facilitating pre-commitment. For each of these strategies, I discuss the specific cost and revenue barriers that a food service operator would face if the strategy were adopted. PMID:25033960
Economic potential of smaller-sized nuclear plants in today's economy
International Nuclear Information System (INIS)
Behrens, C.E.
1984-01-01
In this study, the cost of producing power was modelled for a utility with specified financial and production parameters. Two reference cases were considered: in one, it was assumed that the utility would build 400-megawatt nuclear units as necessary to meet its growth in load; in the second, that it would meet its load growth by building 1200-MW units. The smaller plants were assumed to cost 12 percent more per kilowatt than the larger units. The object was to see if the lower financing costs of the 400-megawatt units were enough to overcome the larger plants' economies of scale. In addition to the reference cases, the sensitivity of the cost measurement to changes in various parameters was modelled. The parameters tested included interest rates, fuel mix, cost differential between the 400-megawatt and 1200-megawatt plants, and the rate of growth in load. The results of these cases indicate strongly that small nuclear power plants could have a market
An atlas of the smaller maps in orientable and nonorientable surfaces
Jackson, David
2000-01-01
Maps are beguilingly simple structures with deep and ubiquitous properties. They arise in an essential way in many areas of mathematics and mathematical physics, but require considerable time and computational effort to generate. Few collected drawings are available for reference, and little has been written, in book form, about their enumerative aspects. An Atlas of the Smaller Maps in Orientable and Nonorientable Surfaces is the first book to provide complete collections of maps along with their vertex and face partitions, number of rootings, and an index number for cross referencing. It provides an explanation of axiomatization and encoding, and serves as an introduction to maps as a combinatorial structure. The Atlas lists the maps first by genus and number of edges, and gives the embeddings of all graphs with at most five edges in orientable surfaces, thus presenting the genus distribution for each graph. Exemplifying the use of the Atlas, the authors explore two substantial conjectures with origins in ...
The Problem with Big Data: Operating on Smaller Datasets to Bridge the Implementation Gap.
Mann, Richard P; Mushtaq, Faisal; White, Alan D; Mata-Cervantes, Gabriel; Pike, Tom; Coker, Dalton; Murdoch, Stuart; Hiles, Tim; Smith, Clare; Berridge, David; Hinchliffe, Suzanne; Hall, Geoff; Smye, Stephen; Wilkie, Richard M; Lodge, J Peter A; Mon-Williams, Mark
2016-01-01
Big datasets have the potential to revolutionize public health. However, there is a mismatch between the political and scientific optimism surrounding big data and the public's perception of its benefit. We suggest a systematic and concerted emphasis on developing models derived from smaller datasets to illustrate to the public how big data can produce tangible benefits in the long term. In order to highlight the immediate value of a small data approach, we produced a proof-of-concept model predicting hospital length of stay. The results demonstrate that existing small datasets can be used to create models that generate a reasonable prediction, facilitating health-care delivery. We propose that greater attention (and funding) needs to be directed toward the utilization of existing information resources in parallel with current efforts to create and exploit "big data."
New algorithm for detecting smaller retinal blood vessels in fundus images
LeAnder, Robert; Bidari, Praveen I.; Mohammed, Tauseef A.; Das, Moumita; Umbaugh, Scott E.
2010-03-01
About 4.1 million Americans suffer from diabetic retinopathy. To help automatically diagnose various stages of the disease, a new blood-vessel-segmentation algorithm based on spatial high-pass filtering was developed to automatically segment blood vessels, including the smaller ones, with low noise. Methods: Image database: Forty, 584 x 565-pixel images were collected from the DRIVE image database. Preprocessing: Green-band extraction was used to obtain better contrast, which facilitated better visualization of retinal blood vessels. A spatial highpass filter of mask-size 11 was applied. A histogram stretch was performed to enhance contrast. A median filter was applied to mitigate noise. At this point, the gray-scale image was converted to a binary image using a binary thresholding operation. Then, a NOT operation was performed by gray-level value inversion between 0 and 255. Postprocessing: The resulting image was AND-ed with its corresponding ring mask to remove the outer-ring (lens-edge) artifact. At this point, the above algorithm steps had extracted most of the major and minor vessels, with some intersections and bifurcations missing. Vessel segments were reintegrated using the Hough transform. Results: After applying the Hough transform, both the average peak SNR and the RMS error improved by 10%. Pratt's Figure of Merit (PFM) was decreased by 6%. Those averages were better than [1] by 10-30%. Conclusions: The new algorithm successfully preserved the details of smaller blood vessels and should prove successful as a segmentation step for automatically identifying diseases that affect retinal blood vessels.
Directory of Open Access Journals (Sweden)
Boyle Malcolm J
2009-02-01
Full Text Available Abstract Background Suboptimal bag ventilation in cardiopulmonary resuscitation (CPR has demonstrated detrimental physiological outcomes for cardiac arrest patients. In light of recent guideline changes for resuscitation, there is a need to identify the efficacy of bag ventilation by prehospital care providers. The objective of this study was to evaluate bag ventilation in relation to operator ability to achieve guideline consistent ventilation rate, tidal volume and minute volume when using two different capacity self-inflating bags in an undergraduate paramedic cohort. Methods An experimental study using a mechanical lung model and a simulated adult cardiac arrest to assess the ventilation ability of third year Monash University undergraduate paramedic students. Participants were instructed to ventilate using 1600 ml and 1000 ml bags for a length of two minutes at the correct rate and tidal volume for a patient undergoing CPR with an advanced airway. Ventilation rate and tidal volume were recorded using an analogue scale with mean values calculated. Ethics approval was granted. Results Suboptimal ventilation with the use of conventional 1600 ml bag was common, with 77% and 97% of participants unable to achieve guideline consistent ventilation rates and tidal volumes respectively. Reduced levels of suboptimal ventilation arouse from the use of the smaller bag with a 27% reduction in suboptimal tidal volumes (p = 0.015 and 23% reduction in suboptimal minute volumes (p = 0.045. Conclusion Smaller self-inflating bags reduce the incidence of suboptimal tidal volumes and minute volumes and produce greater guideline consistent results for cardiac arrest patients.
Bozic, Marija M; Karadzic, Jelena B; Kovacevic, Igor M; Marjanovic, Ivan S
2017-06-26
To assess the effect of panretinal laser photocoagulation on ocular pulse amplitude (OPA) in normotensive eyes with proliferative diabetic retinopathy. Prospectively, we performed unilateral argon laser panretinal photocoagulation (PRP) in 30 patients with diabetes mellitus type II and previously untreated bilateral proliferative diabetic retinopathy. Before and 7 and 30 days after the treatment, OPA was measured using dynamic contour tonometer. Compared with the untreated contralateral eyes, laser photocoagulation led to a reduction of OPA. Ocular pulse amplitude did not significantly differ in photocoagulated eyes 7 days after the treatment, but there was a significant difference in OPA 30 days after the treatment. The decrease in OPA values was 15% 7 days after PRP and 40% 30 days after PRP. Ocular pulse amplitude reduction after PRP indirectly informs us about choriocapillary closure, already reported in previous studies.
Metabolic and respiratory costs of increasing song amplitude in zebra finches.
Directory of Open Access Journals (Sweden)
Sue Anne Zollinger
Full Text Available Bird song is a widely used model in the study of animal communication and sexual selection, and several song features have been shown to reflect the quality of the singer. Recent studies have demonstrated that song amplitude may be an honest signal of current condition in males and that females prefer high amplitude songs. In addition, birds raise the amplitude of their songs to communicate in noisy environments. Although it is generally assumed that louder song should be more costly to produce, there has been little empirical evidence to support this assumption. We tested the assumption by measuring oxygen consumption and respiratory patterns in adult male zebra finches (Taeniopygia guttata singing at different amplitudes in different background noise conditions. As background noise levels increased, birds significantly increased the sound pressure level of their songs. We found that louder songs required significantly greater subsyringeal air sac pressure than quieter songs. Though increased pressure is probably achieved by increasing respiratory muscle activity, these increases did not correlate with measurable increases in oxygen consumption. In addition, we found that oxygen consumption increased in higher background noise, independent of singing behaviour. This observation supports previous research in mammals showing that high levels of environmental noise can induce physiological stress responses. While our study did not find that increasing vocal amplitude increased metabolic costs, further research is needed to determine whether there are other non-metabolic costs of singing louder or costs associated with chronic noise exposure.
The Association Between P3 Amplitude at Age 11 and Criminal Offending at Age 23
Gao, Yu; Raine, Adrian; Venables, Peter H.; Mednick, Sarnoff A.
2014-01-01
Reduced P3 amplitude to targets is an information-processing deficit associated with adult antisocial behavior and may reflect dysfunction of the temporal-parietal junction. This study aims to examine whether this deficit precedes criminal offending. From a birth cohort of 1,795 children, 73 individuals who become criminal offenders at age 23 and 123 noncriminal individuals were assessed on P3 amplitude. The two groups did not differ on gender, ethnicity, and social adversity. P3 amplitude was measured over the temporal-parietal junction during a visual continuous performance task at age 11, together with antisocial behavior. Criminal convictions were assessed at age 23. Reduced P3 amplitude at age 11 was associated with increased antisocial behavior at age 11. Criminal offenders showed significantly reduced P3 amplitudes to target stimuli compared to controls. Findings remained significant after controlling for antisocial behavior and hyperactivity at age 11 and alcoholism at age 23. P3 deficits at age 11 are associated with adult crime at age 23, suggesting that reduced P3 may be an early neurobiological marker for cognitive and affective processes subserved by the temporal-parietal junction that place a child at risk for adult crime. PMID:22963083
True amplitude wave equation migration arising from true amplitude one-way wave equations
Zhang, Yu; Zhang, Guanquan; Bleistein, Norman
2003-10-01
One-way wave operators are powerful tools for use in forward modelling and inversion. Their implementation, however, involves introduction of the square root of an operator as a pseudo-differential operator. Furthermore, a simple factoring of the wave operator produces one-way wave equations that yield the same travel times as the full wave equation, but do not yield accurate amplitudes except for homogeneous media and for almost all points in heterogeneous media. Here, we present augmented one-way wave equations. We show that these equations yield solutions for which the leading order asymptotic amplitude as well as the travel time satisfy the same differential equations as the corresponding functions for the full wave equation. Exact representations of the square-root operator appearing in these differential equations are elusive, except in cases in which the heterogeneity of the medium is independent of the transverse spatial variables. Here, we address the fully heterogeneous case. Singling out depth as the preferred direction of propagation, we introduce a representation of the square-root operator as an integral in which a rational function of the transverse Laplacian appears in the integrand. This allows us to carry out explicit asymptotic analysis of the resulting one-way wave equations. To do this, we introduce an auxiliary function that satisfies a lower dimensional wave equation in transverse spatial variables only. We prove that ray theory for these one-way wave equations leads to one-way eikonal equations and the correct leading order transport equation for the full wave equation. We then introduce appropriate boundary conditions at z = 0 to generate waves at depth whose quotient leads to a reflector map and an estimate of the ray theoretical reflection coefficient on the reflector. Thus, these true amplitude one-way wave equations lead to a 'true amplitude wave equation migration' (WEM) method. In fact, we prove that applying the WEM imaging condition
Double logarithmic asymptotics of quark amplitudes with flavour exchange
International Nuclear Information System (INIS)
Kirschner, R.
1982-01-01
Results on the quark scattering and annihilation amplitudes in the Regge region are presented. The perturbative contribution to those amplitudes in the double logarithmic approximation are calculated. In the calculations a method based on dispersion relations and gauge invariance is used. (M.F.W.)
Multi-loop string amplitudes and Riemann surfaces
International Nuclear Information System (INIS)
Taylor, J.G.
1986-01-01
The paper was presented at the workshop on 'Supersymmetry and its applications', Cambridge, United Kingdom, 1985. Super-string theory is discussed under the following topic headings: the functional approach to the string amplitude, Rieman surfaces, the determinants Δsub(epsilon)(1) and Δsub(epsilon)(2), Green's functions, total amplitude, and divergence analysis. (U.K.)
Damping and Frequency Shift of Large Amplitude Electron Plasma Waves
DEFF Research Database (Denmark)
Thomsen, Kenneth; Juul Rasmussen, Jens
1983-01-01
The initial evolution of large-amplitude one-dimensional electron waves is investigated by applying a numerical simulation. The initial wave damping is found to be strongly enhanced relative to the linear damping and it increases with increasing amplitude. The temporal evolution of the nonlinear...
Singularities of elastic scattering amplitude by long-range potentials
International Nuclear Information System (INIS)
Kvitsinsky, A.A.; Komarov, I.V.; Merkuriev, S.P.
1982-01-01
The angular peculiarities and the zero energy singularities of the elastic scattering amplitude by a long-range potential are described. The singularities of the elastic (2 → 2) scattering amplitude for a system of three Coulomb particles are considered [ru
Properties of the scattering amplitude for electron-atom collisions
International Nuclear Information System (INIS)
Combes, J.M.; Tip, A.
1983-02-01
For the scattering of an electron by an atom finiteness of the amplitude at non threshold energies is proved in the framework of the N-body Schroedinger equation. It is also shown that both the direct and exchange amplitudes have analytic continuations for complex values of incident momentum, with pole or cut singularities on the imaginary axis
Miracles in Scattering Amplitudes: from QCD to Gravity
Energy Technology Data Exchange (ETDEWEB)
Volovich, Anastasia [Brown Univ., Providence, RI (United States)
2016-10-09
The goal of my research project "Miracles in Scattering Amplitudes: from QCD to Gravity" involves deepening our understanding of gauge and gravity theories by exploring hidden structures in scattering amplitudes and using these rich structures as much as possible to aid practical calculations.
Weak decay amplitudes in large N/sub c/ QCD
International Nuclear Information System (INIS)
Bardeen, W.A.
1988-10-01
A systematic analysis of nonleptonic decay amplitudes is presented using the large N/sub c/ expansion of quantum chromodynamics. In the K-meson system, this analysis is applied to the calculation of the weak decay amplitudes, weak mixing and CP violation. 10 refs., 5 figs., 2 tabs
Multiphoton states and amplitude k-th power squeezing
International Nuclear Information System (INIS)
Buzek, V.; Jex, I.
1991-01-01
On the basis of the work of d'Ariano and coworkers a new type of multiphoton states is introduced. Amplitude k-th power squeezing of the multiphoton states are analysed. In particular, it is shown that even if the multiphoton states do not exhibit ordinary squeezing they can be amplitude k-th power squeezed
Automated force controller for amplitude modulation atomic force microscopy
Energy Technology Data Exchange (ETDEWEB)
Miyagi, Atsushi, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr; Scheuring, Simon, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr [U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille (France)
2016-05-15
Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollable drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed.
Numerical evaluation of one-loop QCD amplitudes
DEFF Research Database (Denmark)
Badger, Simon David; Biedermann, Benedikt; Uwer, Peter
2012-01-01
We present the publicly available program NGluon allowing the numerical evaluation of primitive amplitudes at one-loop order in massless QCD. The program allows the computation of one-loop amplitudes for an arbitrary number of gluons. The focus of the present article is the extension to one-loop ...
Conformal higher spin scattering amplitudes from twistor space
Energy Technology Data Exchange (ETDEWEB)
Adamo, Tim [Blackett Laboratory, Imperial College, London, SW7 2AZ (United Kingdom); Hähnel, Philipp; McLoughlin, Tristan [School of Mathematics, Trinity College Dublin, College Green, Dublin 2 (Ireland)
2017-04-04
We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point (MHV)-bar amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.
Simplicity in the structure of QED and gravity amplitudes
Energy Technology Data Exchange (ETDEWEB)
Badger, Simon [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Bjerrum-Bohr, N.E.J. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Vanhove, Pierre [Institut des Hautes Etudes Scientifiques IHES, Bures sur Yvette (France); CEA, IPhT, CNRS, URA, Gif-sur-Yvette, (France). Inst. de Physique Theorique
2008-11-15
We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED 'no-triangle' property is true for all helicity configurations and has similarities to the 'notriangle' property found in the case of maximal N=8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude. (orig.)
Simplicity in the structure of QED and gravity amplitudes
International Nuclear Information System (INIS)
Badger, Simon; Bjerrum-Bohr, N.E.J.; Vanhove, Pierre; CEA, IPhT, CNRS, URA, Gif-sur-Yvette,
2008-11-01
We investigate generic properties of one-loop amplitudes in unordered gauge theories in four dimensions. For such theories the organisation of amplitudes in manifestly crossing symmetric expressions poses restrictions on their structure and results in remarkable cancellations. We show that one-loop multi-photon amplitudes in QED with at least eight external photons are given only by scalar box integral functions. This QED 'no-triangle' property is true for all helicity configurations and has similarities to the 'notriangle' property found in the case of maximal N=8 supergravity. Results are derived both via a world-line formalism as well as using on-shell unitarity methods. We show that the simple structure of the loop amplitude originates from the extremely good BCFW scaling behaviour of the QED tree-amplitude. (orig.)
High Frequency Amplitude Detector for GMI Magnetic Sensors
Directory of Open Access Journals (Sweden)
Aktham Asfour
2014-12-01
Full Text Available A new concept of a high-frequency amplitude detector and demodulator for Giant-Magneto-Impedance (GMI sensors is presented. This concept combines a half wave rectifier, with outstanding capabilities and high speed, and a feedback approach that ensures the amplitude detection with easily adjustable gain. The developed detector is capable of measuring high-frequency and very low amplitude signals without the use of diode-based active rectifiers or analog multipliers. The performances of this detector are addressed throughout the paper. The full circuitry of the design is given, together with a comprehensive theoretical study of the concept and experimental validation. The detector has been used for the amplitude measurement of both single frequency and pulsed signals and for the demodulation of amplitude-modulated signals. It has also been successfully integrated in a GMI sensor prototype. Magnetic field and electrical current measurements in open- and closed-loop of this sensor have also been conducted.
Conformal higher spin scattering amplitudes from twistor space
International Nuclear Information System (INIS)
Adamo, Tim; Hähnel, Philipp; McLoughlin, Tristan
2017-01-01
We use the formulation of conformal higher spin (CHS) theories in twistor space to study their tree-level scattering amplitudes, finding expressions for all three-point (MHV)-bar amplitudes and all MHV amplitudes involving positive helicity conformal gravity particles and two negative helicity higher spins. This provides the on-shell analogue for the covariant coupling of CHS fields to a conformal gravity background. We discuss the restriction of the theory to a ghost-free unitary subsector, analogous to restricting conformal gravity to general relativity with a cosmological constant. We study the flat-space limit and show that the restricted amplitudes vanish, supporting the conjecture that in the unitary sector the S-matrix of CHS theories is trivial. However, by appropriately rescaling the amplitudes we find non-vanishing results which we compare with chiral flat-space higher spin theories.
Directory of Open Access Journals (Sweden)
Soomaayeh Heysieat-talab
2010-09-01
Full Text Available Objective(sBupropion is an atypical antidepressant that is widely used in smoke cessation under FDA approval. The study of synaptic effects of bupropion can help to finding out its mechanism(s for stopping nicotine dependence. In this study the effects of perinatal bupropion on the population spike (PS amplitude of neonates were investigated. Materials and Methods Hippocampal slices were prepared from 18-25 days old rat pups. The experimental groups included control and bupropion-treated. Bupropion (40 mg/Kg, i.p. was applied daily in perinatal period as pre-treatment. Due to the studying acute effects, bupropion was also added to the perfusion medium (10, 50, 200 μM for 30 min. The evoked PS was recorded from pyramidal layer of CA1 area, following stimulation of Schaffer collaterals. ResultsA concentration of 10 μM bupropion had no significant effects on the PS amplitude. The 50 μM concentration of bupropion reduced the amplitude of responses in 50% of the studied cases. At a concentration of 200 μM, the recorded PS amplitudes were reduced in all slices (n= 22. Amplitude was completely abolished in 8 out of the 22 slices. The decrease of the PS amplitude was found to be more in the non-pre-treated slices than in the pre-treated slices when both were perfused with 200 μM bupropion.Conclusion The results showed the perinatal exposure to bupropion and its acute effects while indicating that at concentrations of 50 and 200 μM bupropion reduced the PS amplitude. It was also found that there was evidence of synaptic adaptation in comparison of bupropion-treated and non-treated slices whereas they were both perfused with 200 µM.
Joint Inversion of Phase and Amplitude Data of Surface Waves for North American Upper Mantle
Hamada, K.; Yoshizawa, K.
2015-12-01
For the reconstruction of the laterally heterogeneous upper-mantle structure using surface waves, we generally use phase delay information of seismograms, which represents the average phase velocity perturbation along a ray path, while the amplitude information has been rarely used in the velocity mapping. Amplitude anomalies of surface waves contain a variety of information such as anelastic attenuation, elastic focusing/defocusing, geometrical spreading, and receiver effects. The effects of elastic focusing/defocusing are dependent on the second derivative of phase velocity across the ray path, and thus, are sensitive to shorter-wavelength structure than the conventional phase data. Therefore, suitably-corrected amplitude data of surface waves can be useful for improving the lateral resolution of phase velocity models. In this study, we collect a large-number of inter-station phase velocity and amplitude ratio data for fundamental-mode surface waves with a non-linear waveform fitting between two stations of USArray. The measured inter-station phase velocity and amplitude ratios are then inverted simultaneously for phase velocity maps and local amplification factor at receiver locations in North America. The synthetic experiments suggest that, while the phase velocity maps derived from phase data only reflect large-scale tectonic features, those from phase and amplitude data tend to exhibit better recovery of the strength of velocity perturbations, which emphasizes local-scale tectonic features with larger lateral velocity gradients; e.g., slow anomalies in Snake River Plain and Rio Grande Rift, where significant local amplification due to elastic focusing are observed. Also, the spatial distribution of receiver amplification factor shows a clear correlation with the velocity structure. Our results indicate that inter-station amplitude-ratio data can be of help in reconstructing shorter-wavelength structures of the upper mantle.
Park, Ki-Hoon; Shin, Dong-Gu; Cho, Kyung-Hyun
2014-07-01
Until now, there has been limited information on the effects of smoking on atherogenesis and senescence in the context of lipoprotein parameters, particularly in young smokers who have smoked fewer than 10 cigarettes per day for 3 years. In this study, lipoprotein profiles and functions were compared between smoker (n = 21) and control groups (n = 20). In the smoking group, ferric ion reduction abilities of serum and high-density lipoprotein (HDL) fractions were significantly reduced, and low-density lipoprotein (LDL) was severely oxidized. All lipoprotein particles from the smoker group showed higher advanced glycated end products with more triglyceride (TG) content compared with the control group. Lipoproteins from smokers showed faster agarose gel electromobility as well as greater smear band intensity in SDS-PAGE due to oxidation and glycation. LDL from smokers was more sensitive to oxidation and promoted foam cell forma-tion in macrophages. Gel filtration column chromatography revealed that the protein and cholesterol peaks of VLDL and LDL were elevated in the smoker group, whereas those of HDL were reduced. Human dermal fibroblast cells from the smoker group showed severe senescence following treatment with HDL2 and HDL3. Although HDL from young smokers showed impaired antioxidant ability, smaller particle size, and increased TG content, cholesteryl ester transfer protein activities were greatly enhanced in the serum and HDL fractions of the smoker group. In conclusion, smoking can cause production of dysfunctional lipoproteins having a smaller particle size that exacerbate senescence and atherogenic progress due to oxidation and glycation. © The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.
Fleet view of electrified transportation reveals smaller potential to reduce GHG emissions
International Nuclear Information System (INIS)
Meinrenken, Christoph J.; Lackner, Klaus S.
2015-01-01
Highlights: • Novel framework compares GHG of plugins vs. hybrids for any vehicle type/performance. • Fleet GHG can be compared without forecasting market penetrations of vehicle sizes. • GHG/km for pure electrics must account for limited range using novel, modified Utility Factor. • Applied to the US, this points to smaller GHG reduction at fleet level than traditional fleet analyses. - Abstract: Plugin and hybrid vehicles have been shown to offer possible reductions in greenhouse gas (GHG) emissions, depending on grid-carbon-intensity, range and thus life-cycle battery emissions and vehicle weight, and on trip patterns. We present a framework that enables GHG comparisons (well-to-wheel plus storage manufacturing) for three drivetrains (pure-electric, gasoline-hybrid, and plugin-hybrid), both for individual vehicles and for fleets. The framework captures effects of grid- versus vehicle-based electricity generation, grid transmission and charging losses, and manufacturing and carrying batteries. In contrast to previous work, GHG comparisons can be obtained for heterogeneous fleets of varying vehicle sizes (cars, vans, buses, trucks) and performances, without requiring forecasting of such vehicle specs and their respective market penetrations. Further, we show how a novel adaptation of the Utility Factor concept from plug-in-hybrids to mixed fleets of battery-only and gasoline-hybrids is crucial to quantifying battery-only-vehicles’ impact on fleet-wide GHG. To account for regional variations and possible future technology improvements, we show scenarios over a wide spectrum of grid-carbon-intensities (50–1200 g CO 2 e/kW h at wall), vehicle range (∼5–500 km), battery energy densities, and battery life-cycle GHG. Model uncertainties are quantified via sensitivity tests. Applying the framework to trip patterns of US passenger transportation, we find that owing to the interplay of GHG/km, battery size, all-electric range, and trip patterns, GHG
Rogers, Mark A; Yamasue, Hidenori; Abe, Osamu; Yamada, Haruyasu; Ohtani, Toshiyuki; Iwanami, Akira; Aoki, Shigeki; Kato, Nobumasa; Kasai, Kiyoto
2009-12-30
Although post-traumatic stress disorder (PTSD) may be seen to represent a failure to extinguish learned fear, significant aspects of the pathophysiology relevant to this hypothesis remain unknown. Both the amygdala and hippocampus are necessary for fear extinction occur, and thus both regions may be abnormal in PTSD. Twenty-five people who experienced the Tokyo subway sarin attack in 1995, nine who later developed PTSD and 16 who did not, underwent magnetic resonance imaging (MRI) with manual tracing to determine bilateral amygdala and hippocampus volumes. At the time of scanning, one had PTSD and eight had a history of PTSD. Results indicated that the group with a history of PTSD had significantly smaller mean bilateral amygdala volume than did the group that did not develop PTSD. Furthermore, left amygdala volume showed a significant negative correlation with severity of PTSD symptomatology as well as reduced gray matter density in the left anterior cingulate cortex. To our knowledge, this is the first observation of an association between PTSD and amygdala volume. Furthermore the apparent interplay between amygdala and anterior cingulate cortex represents support at the level of gross brain morphology for the theory of PTSD as a failure of fear extinction.
Zhang, Ruihua; Ren, Ye; Liu, Chunyan; Xu, Na; Li, Xiaoli; Cong, Fengyu; Ristaniemi, Tapani; Wang, YuPing
2017-09-01
Neural activity of the epileptic human brain contains low- and high-frequency oscillations in different frequency bands, some of which have been used as reliable biomarkers of the epileptogenic brain areas. However, the relationship between the low- and high-frequency oscillations in different cortical areas during the period from pre-seizure to post-seizure has not been completely clarified. We recorded electrocorticogram data from the temporal lobe and hippocampus of seven patients with temporal lobe epilepsy. The modulation index based on the Kullback-Leibler distance and the phase-amplitude coupling co-modulogram were adopted to quantify the coupling strength between the phase of low-frequency oscillations (0.2-10Hz) and the amplitude of high-frequency oscillations (11-400Hz) in different seizure epochs. The time-varying phase-amplitude modulogram was used to analyze the phase-amplitude coupling pattern during the entire period from pre-seizure to post-seizure in both the left and right temporal lobe and hippocampus. Channels with strong modulation index were compared with the seizure onset channels identified by the neurosurgeons and the resection channels in the clinical surgery. The phase-amplitude coupling strength (modulation index) increased significantly in the mid-seizure epoch and decrease significantly in seizure termination and post-seizure epochs (ptemporal cortex and hippocampus. The "fall-max" phase-amplitude modulation pattern, i.e., high-frequency amplitudes were largest in the low-frequency phase range [-π, 0], which corresponded to the falling edges of low-frequency oscillations, appeared in the middle period of the seizures at epileptic focus channels. Channels with strong modulation index appeared on the corresponding left or right temporal cortex of surgical resection and overlapped with the clinical resection zones in all patients. The "fall-max" pattern between the phase of low-frequency oscillation and amplitude of high
Directory of Open Access Journals (Sweden)
Ahmad Asmedi
2016-02-01
Full Text Available ABSTRACT Painful Diabetic Neuropathy (PDN is a common complication of diabetes mellitus (DM. Disruption in presynaptic inhibition in dorsal horn of the spinal cord has been proposed as one of the pathomechanism of PDN. Previous research showed that presynaptic inhibition can be detected by H-reflex examination. The aim of this study was to know whether the reduction of presynaptic inhibition in spinal dorsal horn of PDN patients really exist, and detectable by H-reflex examination. It was cohort prospective involving 141 (58 men, 83 women patients with DM and impaired glucose tolerance (IGT between the ages of 40 and 61 years from several health facilities in Yogyakarta. All patients underwent clinical, laboratory and electrodiagnostic examination. Demographic, clinical and electrodiagnostic data were collected and analyzed. By survival analysis there were 25 new cases of PDN (12.12% cumulative incidence. Using survival Kaplan Meier analysis, the significant hazard ratio for PDN were 12.81 for median motor nerve amplitude, 5.74 for median nerve distal latency, 3.71 for median sensory nerve amplitude, 6.33 for median sensory latency, 3.4 for tibial nerve amplitude, 3.48 for tibial nerve distal latency, 2.29 for sural nerve amplitude, 4.47 for sural nerve latency, 3.99 for H-reflex latency, 5.88 for H-reflex amplitude, and 17.83 for Diabetic Neuropathy (DN status. Using hazard proportional cox analysis, only H amplitude and DN status (DNS score were significantly correlated with PDN (p= 0.026; hazard ratio = 15.450; CI 95%= 1.39 – 171.62 for H amplitude and p= 0.030; hazard ratio = 10.766; CI 95%=1.26 – 92.09 for DN status. This study showed that depression of H-reflex amplitude was correlated with the occurrence of PDN. This result proves that there was presynaptic inhibition process in PDN that manifests as low H-reflex amplitude.
A heterodyne interferometer with periodic nonlinearities smaller than ±10 pm
International Nuclear Information System (INIS)
Weichert, C; Köchert, P; Köning, R; Flügge, J; Andreas, B; Kuetgens, U; Yacoot, A
2012-01-01
The PTB developed a new optical heterodyne interferometer in the context of the European joint research project ‘Nanotrace’. A new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized. Furthermore, the interferometer has the resolution of a double-path interferometer, compensates for possible angle variations between the mirrors and the interferometer optics and offers a minimal path difference between the reference and the measurement arm. Additionally, a new heterodyne phase evaluation based on an analogue to digital converter board with embedded field programmable gate arrays was developed, providing a high-resolving capability in the single-digit picometre range. The nonlinearities were characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods of the optical interferometer. Assuming an error-free x-ray interferometer, the nonlinearities are considered to be the deviation of the measured displacement from a best-fit line. For the proposed interferometer, nonlinearities smaller than ±10 pm were observed without any quadrature fringe correction. (paper)
A heterodyne interferometer with periodic nonlinearities smaller than ±10 pm
Weichert, C.; Köchert, P.; Köning, R.; Flügge, J.; Andreas, B.; Kuetgens, U.; Yacoot, A.
2012-09-01
The PTB developed a new optical heterodyne interferometer in the context of the European joint research project ‘Nanotrace’. A new optical concept using plane-parallel plates and spatially separated input beams to minimize the periodic nonlinearities was realized. Furthermore, the interferometer has the resolution of a double-path interferometer, compensates for possible angle variations between the mirrors and the interferometer optics and offers a minimal path difference between the reference and the measurement arm. Additionally, a new heterodyne phase evaluation based on an analogue to digital converter board with embedded field programmable gate arrays was developed, providing a high-resolving capability in the single-digit picometre range. The nonlinearities were characterized by a comparison with an x-ray interferometer, over a measurement range of 2.2 periods of the optical interferometer. Assuming an error-free x-ray interferometer, the nonlinearities are considered to be the deviation of the measured displacement from a best-fit line. For the proposed interferometer, nonlinearities smaller than ±10 pm were observed without any quadrature fringe correction.
Why droplet dimension can be larger than, equal to, or smaller than the nanowire dimension
Mohammad, S. Noor
2009-11-01
Droplets play central roles in the nanowire (NW) growth by vapor phase mechanisms. These mechanisms include vapor-liquid-solid (VLS), vapor-solid-solid or vapor-solid (VSS), vapor-quasisolid-solid or vapor-quasiliquid-solid (VQS), oxide-assisted growth (OAG), and self-catalytic growth (SCG) mechanisms. Fundamentals of the shape, size, characteristics, and dynamics of droplets and the impacts of them on the NW growth, have been studied. The influence of growth techniques, growth parameters (e.g., growth temperature, partial pressure, gas flow rates, etc.), thermodynamic conditions, surface and interface energy, molar volume, chemical potentials, etc. have been considered on the shapes and sizes of droplets. A model has been presented to explain why droplets can be larger than, equal to, or smaller than the associated NWs. Various growth techniques have been analyzed to understand defects created in NWs. Photoluminescence characteristics have been presented to quantify the roles of droplets in the creation of NW defects. The study highlights the importance of the purity of the droplet material. It attests to the superiority of the SCG mechanism, and clarifies the differences between the VSS, VQS, VLS, and SCG mechanisms. It explains why droplets produced by some mechanisms are visible but droplets produced by some other mechanisms are not visible. It elucidates the formation mechanisms of very large and very small droplets, and discusses the ground rules for droplets creating necked NWs. It puts forth reasons to demonstrate that very large droplets may not behave as droplets.
Multiple Smaller Missions as a Direct Pathway to Mars Sample Return
Niles, P. B.; Draper, D. S.; Evans, C. A.; Gibson, E. K.; Graham, L. D.; Jones, J. H.; Lederer, S. M.; Ming, D.; Seaman, C. H.; Archer, P. D.;
2012-01-01
Recent discoveries by the Mars Exploration Rovers, Mars Express, Mars Odyssey, and Mars Reconnaissance Orbiter spacecraft include multiple, tantalizing astrobiological targets representing both past and present environments on Mars. The most desirable path to Mars Sample Return (MSR) would be to collect and return samples from that site which provides the clearest examples of the variety of rock types considered a high priority for sample return (pristine igneous, sedimentary, and hydrothermal). Here we propose an MSR architecture in which the next steps (potentially launched in 2018) would entail a series of smaller missions, including caching, to multiple landing sites to verify the presence of high priority sample return targets through in situ analyses. This alternative architecture to one flagship-class sample caching mission to a single site would preserve a direct path to MSR as stipulated by the Planetary Decadal Survey, while permitting investigation of diverse deposit types and providing comparison of the site of returned samples to other aqueous environments on early Mars
The Role of Interpretation in the Internationalization of Smaller Brazilian Firms
Directory of Open Access Journals (Sweden)
Rene Eugenio Seifert
2012-10-01
Full Text Available This study considers how decision-makers in smaller firms interpret the means and conditions of internationalization, and how different modes of interpretation are likely to inform action choices in this process. Drawing on 58 qualitative interviews with the leaders of Brazilian small and medium-sized enterprises (SMEsin the clothing industry located in the state of Paraná, the results support the contention that different understandings given to the means/conditions of internationalization are associated with different action choices. More specifically, the results indicate that: (a interpretation changes the criteria and parameters by which rational choices on internationalization are made; (b a comprehensive explanation of internationalization on the basis of situational characteristics is likely to be inconclusive without taking into account decision-makers’ interpretations; (c particular meanings given to internationalization are likely to inform choice in different ways, (d managers act on the basis of their inter-subjectively negotiated, shared and sustained reality; and (e investigative proximity with practitioners is pivotal in order to comprehensively account for their interpretations.
IRIS-50. A 50 MWe advanced PWR design for smaller, regional grids and specialized applications
International Nuclear Information System (INIS)
Petrovic, Bojan; Carelli, Mario; Conway, Larry; Hundal, Rolv; Barbaso, Enrico; Gamba, Federica; Centofante, Mario
2009-01-01
IRIS is an advanced, medium-power (1000 MWt or ∼335 MWe) advanced PWR design of integral configuration, that has gained wide recognition due to its innovative 'safety-by-design' safety approach. In spite of its smaller size compared to large monolithic nuclear power plants, it is economically competitive due to its simplicity and advantages of modular deployment. However, the optimum power level for a class of specific applications (e.g., power generation in small regional isolated grids; water desalination and biodiesel production at remote locations; autonomous power source for special applications, etc.) may be even lower, of the order of tens rather than hundreds of MWe. The simple and robust IRIS 335 MWe design provides a solid basis for establishing a 20-100 MWe design, utilizing the same safety and economics principles, so that it will retain economic attractiveness compared to other alternatives of the same power level. A conceptual 50 MWe design, IRIS-50, was initially developed and then assessed in a 2001 report to the US Congress on small and medium reactors, as a design mature enough to have deployment potential within a decade. In the meantime, while the main efforts have focused on the 335 MWe design completion and licensing, parallel efforts have progressed toward the preliminary design of IRIS-50. This paper summarizes the main IRIS-50 features and presents an update on its design status. (author)
Retinal Nerve Fiber Layer Converges More Convexly on Normal Smaller Optic Nerve Head.
Jung, Kyoung In; Shin, Jeong Ah; Park, Hae-Young Lopilly; Park, Chan Kee
2015-08-01
To investigate retinal nerve fiber layer (RNFL) configuration in the optic nerve head (ONH) and peripapillary area according to disc size and to determine whether it explains cup discrepancy among eyes with different disc sizes. Horizontal and vertical RNFL curvature and mean thickness were measured using confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph) in 63 normal subjects grouped by disc size. Average and quadrant RNFL thickness, disc size, average cup-to-disc ratio (CDR), and convergence angle at the optic disc were also measured using Cirrus HD-optical coherence tomography. The relationships between disc size and RNFL curvature, thickness, angle at optic disc, and CDR were evaluated. RNFL curvature and convergence angle reflects convexity "on" and "into" the optic disc, respectively. CDR was smaller for small discs and was positively correlated with disc size (Poptic disc were positively correlated with disc size (POptic disc area was negatively correlated with mean RNFL thickness at the optic disc margin measured by HRT (P=0.002), but not in the peripapillary area by optical coherence tomography. Using imaging techniques, we demonstrated that the shape of the RNFLs converging "on" and entering "into" the optic disc was more convex for small optic discs compared with large discs. A low CDR for small discs could be mediated by these RNFL profiles at the ONH, which may guide the clinical evaluation of glaucomatous ONH damage.
International Nuclear Information System (INIS)
Suarez Antola, R.
2008-11-01
The cores of nuclear reactors, including its structural parts and cooling fluids, are complex mechanical systems able to vibrate in a set of normal modes and frequencies, if suitable perturbed. The cyclic variations in the strain state of the core materials may produce changes in density. Changes in density modify the reactivity. Changes in reactivity modify thermal power. Modifications in thermal power produce variations in temperature fields. Variations in temperature produce variations in strain due to thermal-elastic effects. If the variation of the temperature field is fast enough and if the Doppler Effect and other stabilizing prompt effects in the fuel are weak enough, a fast oscillatory instability could be produced, coupled with mechanical vibrations of small amplitude. A recently constructed, simple mathematical model of nuclear reactor kinetics, that improves the one due to A.S. Thompson, is reviewed. It was constructed in order to study, in a first approximation, the stability of the reactor: a nonlinear nuclear-thermal oscillator (that corresponds to reactor point kinetics with thermal-elastic feedback and with frozen delayed neutron effects) is coupled nonlinearly with a linear mechanical-thermal oscillator (that corresponds to the first normal mode of mechanical vibrations excited by thermo-elastic effects). This mathematical model is studied here from the standpoint of mechanical vibrations. It is shown how, under certain conditions, a suitable mechanical perturbation could elicit fast and growing oscillatory instabilities in the reactor power. Applying the asymptotic method due to Krylov, Bogoliubov and Mitropolsky, analytical formulae that may be used in the calculation of the time varying amplitude and phase of the mechanical oscillations are given, as functions of the mechanical, thermal and nuclear parameters of the reactor. The consequences for the mechanical integrity of the reactor are assessed. Some conditions, mainly, but not exclusively
DEFF Research Database (Denmark)
Christensen, M. G.; Jensen, Søren Holdt
2006-01-01
A method for amplitude modulated sinusoidal audio coding is presented that has low complexity and low delay. This is based on a subband processing system, where, in each subband, the signal is modeled as an amplitude modulated sum of sinusoids. The envelopes are estimated using frequency......-domain linear prediction and the prediction coefficients are quantized. As a proof of concept, we evaluate different configurations in a subjective listening test, and this shows that the proposed method offers significant improvements in sinusoidal coding. Furthermore, the properties of the frequency...
DEFF Research Database (Denmark)
Ghoreishy, Hoda; Varjani, Ali Yazdian; Mohamadian, Mustafa
2013-01-01
Compared to the conventional selective harmonic elimination-pulse width modulation (SHE-PWM), the selective harmonic elimination-pulse width and amplitude modulation (SHE-PWAM) control strategy results in significant improvements in the performance of CHB inverters. This fact is due to considerin...
Systematic assessment of noise amplitude generated by toys intended for young children.
Mahboubi, Hossein; Oliaei, Sepehr; Badran, Karam W; Ziai, Kasra; Chang, Janice; Zardouz, Shawn; Shahriari, Shawn; Djalilian, Hamid R
2013-06-01
To systematically evaluate the noise generated by toys targeted for children and to compare the results over the course of 4 consecutive holiday shopping seasons. Experimental study. Academic medical center. During 2008-2011, more than 200 toys marketed for children older than 6 months were screened for loudness. The toys with sound output of more than 80 dBA at speaker level were retested in a soundproof audiometry booth. The generated sound amplitude of each toy was measured at speaker level and at 30 cm away from the speaker. Ninety different toys were analyzed. The mean (SD) noise amplitude was 100 (8) dBA (range, 80-121 dBA) at the speaker level and 80 (11) dBA (range, 60-109 dBA) at 30 cm away from the speaker. Eighty-eight (98%) had more than an 85-dBA noise amplitude at speaker level, whereas 19 (26%) had more than an 85-dBA noise amplitude at a 30-cm distance. Only the mean noise amplitude at 30 cm significantly declined during the studied period (P toys specified for different age groups. Our findings demonstrate the persistence of extremely loud toys marketed for very young children. Acoustic trauma from toys remains a potential risk factor for noise-induced hearing loss in this age group, warranting promotion of public awareness and regulatory considerations for manufacture and marketing of toys.
Relativistic effects on large amplitude nonlinear Langmuir waves in a two-fluid plasma
International Nuclear Information System (INIS)
Nejoh, Yasunori
1994-07-01
Large amplitude relativistic nonlinear Langmuir waves are analyzed by the pseudo-potential method. The existence conditions for nonlinear Langmuir waves are confirmed by considering relativistic high-speed electrons in a two-fluid plasma. The significant feature of this investigation is that the propagation of nonlinear Langmuir waves depends on the ratio of the electron streaming velocity to the velocity of light, the normalized potential and the ion mass to electron mass ratio. The constant energy is determined by the specific range of the relativistic effect. In the non-relativistic limit, large amplitude relativistic Langmuir waves do not exist. The present investigation predicts new findings of large amplitude nonlinear Langmuir waves in space plasma phenomena in which relativistic electrons are important. (author)
Smooth Pursuit Saccade Amplitude Modulation During Exposure to Microgravity
Reschke, M. F.; Kozlovskaya, I. B.; Sayenko, D. G.; Sayenko, I.; Somers, J. T.; Paloski, W. H.
2002-01-01
main sequence . This difference in the regression slopes between flight phase, head/eye condition (EO or EH), and pursuit target frequency was observed across all subjects (statistically significant at the ptendency (not significant) for both saccade amplitude and peak velocity to increase during the postflight testing. This tendency had vanished by R+ 1. Of particular interest was the redistribution of saccades during the latter stages of the flight and immediately postflight in the EO condition. At the 1.0 Hz frequency the saccades tended to be clustered near the lowest target velocity. It was also interesting to note that gaze performance (eye in skull + head in space) was consistently better during the EH condition; a finding also observed by our Russian colleagues. As the results of the long duration flight become available we expect that they will not only show that postflight effects will be similar to those observed during the short duration flights, but will also last for a greater period of time following flight. It is not clear what mechanism is responsible for the decreased peak saccadic velocity during flight unless the change is related to the control of retinal slip. For example, it is possible that saccades will tend to initially undershoot their targets by a small percentage and these saccades are then followed, if vision is available, by a small augmenting corrective saccade. It has been postulated that the functional significance of this undershooting tendency is to maintain the spatial representation of the target on the same side of the fovea (as opposedo racing across the fovea) and hence in the same cerebral hemisphere that initiated the primary saccade thus minimizing delays caused by an intra-hemispheric transfer of information . One could also speculate that with saccade velocities greater than normal, additional corrective saccades would be required to bring the target back on the fovea. A less plausible explanation of our findings could be
Large amplitude ion-acoustic solitons in dusty plasmas
International Nuclear Information System (INIS)
Tiwari, R. S.; Jain, S. L.; Mishra, M. K.
2011-01-01
Characteristics of ion-acoustic soliton in dusty plasma, including the dynamics of heavily charged massive dust grains, are investigated following the Sagdeev Potential formalism. Retaining fourth order nonlinearities of electric potential in the expansion of the Sagdeev Potential in the energy equation for a pseudo particle and integrating the resulting energy equation, large amplitude soliton solution is determined. Variation of amplitude (A), half width (W) at half maxima and the product P = AW 2 of the Korteweg-deVries (KdV), dressed and large amplitude soliton as a function of wide range of dust concentration are numerically studied for recently observed parameters of dusty plasmas. We have also presented the region of existence of large amplitude ion-acoustic soliton in the dusty plasma by analyzing the structure of the pseudo potential. It is found that in the presence of positively charged dust grains, system supports only compressive solitons, on the other hand, in the presence of negatively charged dust grains, the system supports compressive solitons up to certain critical concentration of dust grains and above this critical concentration, the system can support rarefactive solitons also. The effects of dust concentration, charge, and mass of the dust grains, on the characteristics of KdV, dressed and large amplitude the soliton, i.e., amplitude (A), half width at half maxima (W), and product of amplitude (A) and half width at half maxima (P = AW 2 ), are discussed in detail
Fringe image analysis based on the amplitude modulation method.
Gai, Shaoyan; Da, Feipeng
2010-05-10
A novel phase-analysis method is proposed. To get the fringe order of a fringe image, the amplitude-modulation fringe pattern is carried out, which is combined with the phase-shift method. The primary phase value is obtained by a phase-shift algorithm, and the fringe-order information is encoded in the amplitude-modulation fringe pattern. Different from other methods, the amplitude-modulation fringe identifies the fringe order by the amplitude of the fringe pattern. In an amplitude-modulation fringe pattern, each fringe has its own amplitude; thus, the order information is integrated in one fringe pattern, and the absolute fringe phase can be calculated correctly and quickly with the amplitude-modulation fringe image. The detailed algorithm is given, and the error analysis of this method is also discussed. Experimental results are presented by a full-field shape measurement system where the data has been processed using the proposed algorithm. (c) 2010 Optical Society of America.
Broadband metasurface holograms: toward complete phase and amplitude engineering.
Wang, Qiu; Zhang, Xueqian; Xu, Yuehong; Gu, Jianqiang; Li, Yanfeng; Tian, Zhen; Singh, Ranjan; Zhang, Shuang; Han, Jiaguang; Zhang, Weili
2016-09-12
As a revolutionary three-dimensional imaging technique, holography has attracted wide attention for its ability to photographically record a light field. However, traditional phase-only or amplitude-only modulation holograms have limited image quality and resolution to reappear both amplitude and phase information required of the objects. Recent advances in metasurfaces have shown tremendous opportunities for using a planar design of artificial meta-atoms to shape the wave front of light by optimal control of both its phase and amplitude. Inspired by the concept of designer metasurfaces, we demonstrate a novel amplitude-phase modulation hologram with simultaneous five-level amplitude modulation and eight-level phase modulation. Such a design approach seeks to turn the perceived disadvantages of the traditional phase or amplitude holograms, and thus enable enhanced performance in resolution, homogeneity of amplitude distribution, precision, and signal-to-noise ratio. In particular, the unique holographic approach exhibits broadband characteristics. The method introduced here delivers more degrees of freedom, and allows for encoding highly complex information into designer metasurfaces, thus having the potential to drive next-generation technological breakthroughs in holography.
Marker, Terry L; Felix, Larry G; Linck, Martin B; Roberts, Michael J
2014-09-23
This invention relates to a process for thermochemically transforming biomass or other oxygenated feedstocks into high quality liquid hydrocarbon fuels. In particular, a catalytic hydropyrolysis reactor, containing a deep bed of fluidized catalyst particles is utilized to accept particles of biomass or other oxygenated feedstocks that are significantly smaller than the particles of catalyst in the fluidized bed. The reactor features an insert or other structure disposed within the reactor vessel that inhibits slugging of the bed and thereby minimizes attrition of the catalyst. Within the bed, the biomass feedstock is converted into a vapor-phase product, containing hydrocarbon molecules and other process vapors, and an entrained solid char product, which is separated from the vapor stream after the vapor stream has been exhausted from the top of the reactor. When the product vapor stream is cooled to ambient temperatures, a significant proportion of the hydrocarbons in the product vapor stream can be recovered as a liquid stream of hydrophobic hydrocarbons, with properties consistent with those of gasoline, kerosene, and diesel fuel. Separate streams of gasoline, kerosene, and diesel fuel may also be obtained, either via selective condensation of each type of fuel, or via later distillation of the combined hydrocarbon liquid.
Schwartz, C E; Kunwar, P S; Hirshfeld-Becker, D R; Henin, A; Vangel, M G; Rauch, S L; Biederman, J; Rosenbaum, J F
2015-01-01
Behavioral inhibition (BI) is a genetically influenced behavioral profile seen in 15–20% of 2-year-old children. Children with BI are timid with people, objects and situations that are novel or unfamiliar, and are more reactive physiologically to these challenges as evidenced by higher heart rate, pupillary dilation, vocal cord tension and higher levels of cortisol. BI predisposes to the later development of anxiety, depression and substance abuse. Reduced hippocampal volumes have been observed in anxiety disorders, depression and posttraumatic stress disorder. Animal models have demonstrated that chronic stress can damage the hippocampal formation and implicated cortisol in these effects. We, therefore, hypothesized that the hippocampi of late adolescents who had been behaviorally inhibited as children would be smaller compared with those who had not been inhibited. Hippocampal volume was measured with high-resolution structural magnetic resonance imaging in 43 females and 40 males at 17 years of age who were determined to be BI+ or BI− based on behaviors observed in the laboratory as young children. BI in childhood predicted reduced hippocampal volumes in the adolescents who were offspring of parents with panic disorder, or panic disorder with comorbid major depression. We discuss genetic and environmental factors emanating from both child and parent that may explain these findings. To the best of our knowledge, this is the first study to demonstrate a relationship between the most extensively studied form of temperamentally based human trait anxiety, BI, and hippocampal structure. The reduction in hippocampal volume, as reported by us, suggests a role for the hippocampus in human trait anxiety and anxiety disorder that warrants further investigation. PMID:26196438
Caravaggio, Fernando; Fervaha, Gagan; Iwata, Yusuke; Plitman, Eric; Chung, Jun Ku; Nakajima, Shinichiro; Mar, Wanna; Gerretsen, Philip; Kim, Julia; Chakravarty, Mallar; Mulsant, Benoit; Pollock, Bruce; Mamo, David; Remington, Gary; Graff-Guerrero, Ariel
2018-01-01
Abstract Background Motivational deficits are prevalent in patients with schizophrenia, persist despite antipsychotic treatment, and predict long‐term outcomes. Evidence suggests that patients with greater amotivation have smaller ventral striatum (VS) volumes. We wished to replicate this finding in a sample of older, chronically medicated patients with schizophrenia. Using structural imaging and positron emission tomography, we examined whether amotivation uniquely predicted VS volumes beyond the effects of striatal dopamine D2/3 receptor (D2/3R) blockade by antipsychotics. Methods Data from 41 older schizophrenia patients (mean age: 60.2 ± 6.7; 11 female) were reanalysed from previously published imaging data. We constructed multivariate linear stepwise regression models with VS volumes as the dependent variable and various sociodemographic and clinical variables as the initial predictors: age, gender, total brain volume, and antipsychotic striatal D2/3R occupancy. Amotivation was included as a subsequent step to determine any unique relationships with VS volumes beyond the contribution of the covariates. In a reduced sample (n = 36), general cognition was also included as a covariate. Results Amotivation uniquely explained 8% and 6% of the variance in right and left VS volumes, respectively (right: β = -.38, t = -2.48, P = .01; left: β = -.31, t = -2.17, P = .03). Considering cognition, amotivation levels uniquely explained 9% of the variance in right VS volumes (β = -.43, t = -0.26, P = .03). Discussion We replicate and extend the finding of reduced VS volumes with greater amotivation. We demonstrate this relationship uniquely beyond the potential contributions of striatal D2/3R blockade by antipsychotics. Elucidating the structural correlates of amotivation in schizophrenia may help develop treatments for this presently irremediable deficit.
Caravaggio, Fernando; Fervaha, Gagan; Iwata, Yusuke; Plitman, Eric; Chung, Jun Ku; Nakajima, Shinichiro; Mar, Wanna; Gerretsen, Philip; Kim, Julia; Chakravarty, M Mallar; Mulsant, Benoit; Pollock, Bruce; Mamo, David; Remington, Gary; Graff-Guerrero, Ariel
2018-03-01
Motivational deficits are prevalent in patients with schizophrenia, persist despite antipsychotic treatment, and predict long-term outcomes. Evidence suggests that patients with greater amotivation have smaller ventral striatum (VS) volumes. We wished to replicate this finding in a sample of older, chronically medicated patients with schizophrenia. Using structural imaging and positron emission tomography, we examined whether amotivation uniquely predicted VS volumes beyond the effects of striatal dopamine D 2/3 receptor (D 2/3 R) blockade by antipsychotics. Data from 41 older schizophrenia patients (mean age: 60.2 ± 6.7; 11 female) were reanalysed from previously published imaging data. We constructed multivariate linear stepwise regression models with VS volumes as the dependent variable and various sociodemographic and clinical variables as the initial predictors: age, gender, total brain volume, and antipsychotic striatal D 2/3 R occupancy. Amotivation was included as a subsequent step to determine any unique relationships with VS volumes beyond the contribution of the covariates. In a reduced sample (n = 36), general cognition was also included as a covariate. Amotivation uniquely explained 8% and 6% of the variance in right and left VS volumes, respectively (right: β = -.38, t = -2.48, P = .01; left: β = -.31, t = -2.17, P = .03). Considering cognition, amotivation levels uniquely explained 9% of the variance in right VS volumes (β = -.43, t = -0.26, P = .03). We replicate and extend the finding of reduced VS volumes with greater amotivation. We demonstrate this relationship uniquely beyond the potential contributions of striatal D 2/3 R blockade by antipsychotics. Elucidating the structural correlates of amotivation in schizophrenia may help develop treatments for this presently irremediable deficit. Copyright © 2017 John Wiley & Sons, Ltd.
Faster diffraction-based overlay measurements with smaller targets using 3D gratings
Li, Jie; Kritsun, Oleg; Liu, Yongdong; Dasari, Prasad; Volkman, Catherine; Hu, Jiangtao
2012-03-01
Diffraction-based overlay (DBO) technologies have been developed to address the overlay metrology challenges for 22nm technology node and beyond. Most DBO technologies require specially designed targets that consist of multiple measurement pads, which consume too much space and increase measurement time. The traditional empirical approach (eDBO) using normal incidence spectroscopic reflectometry (NISR) relies on linear response of the reflectance with respect to overlay displacement within a small range. It offers convenience of quick recipe setup since there is no need to establish a model. However it requires three or four pads per direction (x or y) which adds burden to throughput and target size. Recent advances in modeling capability and computation power enabled mDBO, which allows overlay measurement with reduced number of pads, thus reducing measurement time and DBO target space. In this paper we evaluate the performance of single pad mDBO measurements using two 3D targets that have different grating shapes: squares in boxes and L-shapes in boxes. Good overlay sensitivities are observed for both targets. The correlation to programmed shifts and image-based overlay (IBO) is excellent. Despite the difference in shapes, the mDBO results are comparable for square and L-shape targets. The impact of process variations on overlay measurements is studied using a focus and exposure matrix (FEM) wafer. Although the FEM wafer has larger process variations, the correlation of mDBO results with IBO measurements is as good as the normal process wafer. We demonstrate the feasibility of single pad DBO measurements with faster throughput and smaller target size, which is particularly important in high volume manufacturing environment.
Birds and Roads: Reduced Transit for Smaller Species over Roads within an Urban Environment
Directory of Open Access Journals (Sweden)
Christopher D. Johnson
2017-05-01
important role in determining species presence and crossing likelihood. Dense vegetation is known to benefit smaller species due to the provision of foraging resources and shelter from larger, more aggressive species.
Jump phenomena. [large amplitude responses of nonlinear systems
Reiss, E. L.
1980-01-01
The paper considers jump phenomena composed of large amplitude responses of nonlinear systems caused by small amplitude disturbances. Physical problems where large jumps in the solution amplitude are important features of the response are described, including snap buckling of elastic shells, chemical reactions leading to combustion and explosion, and long-term climatic changes of the earth's atmosphere. A new method of rational functions was then developed which consists of representing the solutions of the jump problems as rational functions of the small disturbance parameter; this method can solve jump problems explicitly.
Elementary amplitudes from full QCD and the stochastic vacuum model
International Nuclear Information System (INIS)
Martini, A.F.; Menon, M.J.
2002-01-01
In a previous work, making use of the gluon gauge-invariant two-point correlation function determined from lattice QCD in the quenched approximation and the stochastic vacuum model, we determined the elementary (parton-parton) scattering amplitude in the momentum transfer space. In this communication we compute the elementary amplitude from new lattice QCD calculations that include the effects of dynamical fermions (full QCD). The main conclusion is that the inclusion of dynamical fermions leads to a normalized elementary amplitude that decreases more quickly with the momentum transfer than that in the quenched approximation. (author)
Renormalization Scale-Fixing for Complex Scattering Amplitudes
Energy Technology Data Exchange (ETDEWEB)
Brodsky, Stanley J.; /SLAC; Llanes-Estrada, Felipe J.; /Madrid U.
2005-12-21
We show how to fix the renormalization scale for hard-scattering exclusive processes such as deeply virtual meson electroproduction by applying the BLM prescription to the imaginary part of the scattering amplitude and employing a fixed-t dispersion relation to obtain the scale-fixed real part. In this way we resolve the ambiguity in BLM renormalization scale-setting for complex scattering amplitudes. We illustrate this by computing the H generalized parton distribution at leading twist in an analytic quark-diquark model for the parton-proton scattering amplitude which can incorporate Regge exchange contributions characteristic of the deep inelastic structure functions.
Calculation and modular properties of multi-loop superstring amplitudes
International Nuclear Information System (INIS)
Danilov, G S
2012-01-01
Multi-loop superstring amplitude is calculated in the conventional gauge where Grassmann moduli are carried by the 2D gravitino field. Generally, instead of the modular symmetry, the amplitudes hold the symmetry under modular transformations added by relevant transformations of the 2D local supersymmetry. If a number of loops are larger than 3, the integration measures are not modular forms. In this case the expression for the amplitude contains an integral over the bound of the fundamental region of the modular group. (paper)
Amplitude Modulation in the δ Sct star KIC 7106205
Directory of Open Access Journals (Sweden)
Bowman Dominic. M.
2015-01-01
Full Text Available The δ Sct star KIC 7106205 showed amplitude modulation in a single p mode, whilst all other p and g modes remained stable in amplitude and phase over 1470 d of the Kepler dataset. The data were divided into 30 time bins of equal length and a series of consecutive Fourier transforms was calculated. A fixed frequency, calculated from a least-squares fit of all data, allowed amplitude and phase for every mode in each time bin to be tracked. The missing p mode energy was not transferred to any other visible modes.
Corrections to the large-angle scattering amplitude
International Nuclear Information System (INIS)
Goloskokov, S.V.; Kudinov, A.V.; Kuleshov, S.P.
1979-01-01
High-energy behaviour of scattering amplitudes is considered within the frames of Logunov-Tavchelidze quasipotential approach. The representation of scattering amplitude of two scalar particles, convenient for the study of its asymptotic properties is given. Obtained are corrections of the main value of scattering amplitude of the first and the second orders in 1/p, where p is the pulse of colliding particles in the system of the inertia centre. An example of the obtained formulas use for a concrete quasipotential is given
Direct Calculation of the Scattering Amplitude Without Partial Wave Analysis
Shertzer, J.; Temkin, A.; Fisher, Richard R. (Technical Monitor)
2001-01-01
Two new developments in scattering theory are reported. We show, in a practical way, how one can calculate the full scattering amplitude without invoking a partial wave expansion. First, the integral expression for the scattering amplitude f(theta) is simplified by an analytic integration over the azimuthal angle. Second, the full scattering wavefunction which appears in the integral expression for f(theta) is obtained by solving the Schrodinger equation with the finite element method (FEM). As an example, we calculate electron scattering from the Hartree potential. With minimal computational effort, we obtain accurate and stable results for the scattering amplitude.
Amplitude-to-frequency converter of radioisotope instruments
International Nuclear Information System (INIS)
Demchenkov, V.P.; Korobkov, I.N.
1988-01-01
An amplitude-to-frequency converter designed for signal processing of radioisotope relay devices is descibed. The basic elements of the converter are a scaling amplifier, an analog-to-digital converter, a code-to-frequency converter, a null-organ, a delay unit and a clock-pulse generator. The designed amplitude-to-frequency converter takes into account a prior information about the signal shape of the energy spectrum. The converter processes input pulses of 0.10 V amplitude and duration more than 2μs. The energy channel number is 64
Gluon cascades and amplitudes in light-front perturbation theory
International Nuclear Information System (INIS)
Cruz-Santiago, C.A.; Staśto, A.M.
2013-01-01
We construct the gluon wave functions, fragmentation functions and scattering amplitudes within the light-front perturbation theory. Recursion relations on the light-front are constructed for the wave functions and fragmentation functions, which in the latter case are the light-front analogs of the Berends–Giele recursion relations. Using general relations between wave functions and scattering amplitudes it is demonstrated how to obtain the maximally-helicity violating amplitudes, and explicit verification of the results is based on simple examples.
Amplitude modulation of charge-density-wave domains in 1T-TaS2 at 300 K
International Nuclear Information System (INIS)
Coleman, R.V.; McNairy, W.W.; Slough, C.G.
1991-01-01
Measurements of the charge-density-wave (CDW) amplitude modulation in 1T-TaS 2 at room temperature have been made using a scanning tunneling microscope (STM) operating in the constant current mode. The amplitude profiles are in good agreement with the profile predicated by the CDW domain model of Nakanishi and Shiba. Interference effects between the atomic and CDW lattices have been analyzed and do not modify these profiles significantly. They represent the true CDW amplitude variation connected with the CDW domain structure
The moving minimum audible angle is smaller during self motion than during source motion.
Directory of Open Access Journals (Sweden)
W. Owen eBrimijoin
2014-09-01
Full Text Available We are rarely perfectly still: our heads rotate in three axes and move in three dimensions, constantly varying the spectral and binaural cues at the ear drums. In spite of this motion, static sound sources in the world are typically perceived as stable objects. This argues that the auditory system – in a manner not unlike the vestibulo-ocular reflex – works to compensate for self motion and stabilize our sensory representation of the world. We tested a prediction arising from this postulate: that self motion should be processed more accurately than source motion.We used an infrared motion tracking system to measure head angle, and real-time interpolation of head related impulse responses to create head-stabilized signals that appeared to remain fixed in space as the head turned. After being presented with pairs of simultaneous signals consisting of a man and a woman speaking a snippet of speech, normal and hearing impaired listeners were asked to report whether the female voice was to the left or the right of the male voice. In this way we measured the moving minimum audible angle (MMAA. This measurement was made while listeners were asked to turn their heads back and forth between ± 15° and the signals were stabilized in space. After this self-motion condition we measured MMAA in a second source-motion condition when listeners remained still and the virtual locations of the signals were moved using the trajectories from the first condition.For both normal and hearing impaired listeners, we found that the MMAA for signals moving relative to the head was ~1-2° smaller when the movement was the result of self motion than when it was the result of source motion, even though the motion with respect to the head was identical. These results as well as the results of past experiments suggest that spatial processing involves an ongoing and highly accurate comparison of spatial acoustic cues with self-motion cues.
A pulse amplitude discriminator with very low-power consuming
International Nuclear Information System (INIS)
Deng Changming; Liu Zhengshan; Zhang Zhiyong; Cheng Chang
2000-01-01
A low-power pulse amplitude discriminator is described. The discriminator circuit is mainly composed of an integrated voltage comparator, MAX921, and owns the characters of very low-power and low operating voltage
Some tree-level string amplitudes in the NSR formalism
International Nuclear Information System (INIS)
Becker, Katrin; Becker, Melanie; Melnikov, Ilarion V.; Robbins, Daniel; Royston, Andrew B.
2015-01-01
We calculate tree level scattering amplitudes for open strings using the NSR formalism. We present a streamlined symmetry-based and pedagogical approach to the computations, which we first develop by checking two-, three-, and four-point functions involving bosons and fermions. We calculate the five-point amplitude for massless gluons and find agreement with an earlier result by Brandt, Machado and Medina. We then compute the five-point amplitudes involving two and four fermions respectively, the general form of which has not been previously obtained in the NSR formalism. The results nicely confirm expectations from the supersymmetric F 4 effective action. Finally we use the prescription of Kawai, Lewellen and Tye (KLT) to compute the amplitudes for the closed string sector.
Amplitude chimeras and chimera death in dynamical networks
International Nuclear Information System (INIS)
Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard
2016-01-01
We find chimera states with respect to amplitude dynamics in a network of Stuart- Landau oscillators. These partially coherent and partially incoherent spatio-temporal patterns appear due to the interplay of nonlocal network topology and symmetry-breaking coupling. As the coupling range is increased, the oscillations are quenched, amplitude chimeras disappear and the network enters a symmetry-breaking stationary state. This particular regime is a novel pattern which we call chimera death. It is characterized by the coexistence of spatially coherent and incoherent inhomogeneous steady states and therefore combines the features of chimera state and oscillation death. Additionally, we show two different transition scenarios from amplitude chimera to chimera death. Moreover, for amplitude chimeras we uncover the mechanism of transition towards in-phase synchronized regime and discuss the role of initial conditions. (paper)
Stora's fine notion of divergent amplitudes
International Nuclear Information System (INIS)
Várilly, Joseph C.; Gracia-Bondía, José M.
2016-01-01
Stora and coworkers refined the notion of divergent quantum amplitude, somewhat upsetting the standard power-counting recipe. This unexpectedly clears the way to new prototypes for free and interacting field theories of bosons of any mass and spin.
Euclidean to Minkowski Bethe-Salpeter amplitude and observables
International Nuclear Information System (INIS)
Carbonell, J.; Frederico, T.; Karmanov, V.A.
2017-01-01
We propose a method to reconstruct the Bethe-Salpeter amplitude in Minkowski space given the Euclidean Bethe-Salpeter amplitude - or alternatively the light-front wave function - as input. The method is based on the numerical inversion of the Nakanishi integral representation and computing the corresponding weight function. This inversion procedure is, in general, rather unstable, and we propose several ways to considerably reduce the instabilities. In terms of the Nakanishi weight function, one can easily compute the BS amplitude, the LF wave function and the electromagnetic form factor. The latter ones are very stable in spite of residual instabilities in the weight function. This procedure allows both, to continue the Euclidean BS solution in the Minkowski space and to obtain a BS amplitude from a LF wave function. (orig.)
Laser beam complex amplitude measurement by phase diversity.
Védrenne, Nicolas; Mugnier, Laurent M; Michau, Vincent; Velluet, Marie-Thérèse; Bierent, Rudolph
2014-02-24
The control of the optical quality of a laser beam requires a complex amplitude measurement able to deal with strong modulus variations and potentially highly perturbed wavefronts. The method proposed here consists in an extension of phase diversity to complex amplitude measurements that is effective for highly perturbed beams. Named camelot for Complex Amplitude MEasurement by a Likelihood Optimization Tool, it relies on the acquisition and processing of few images of the beam section taken along the optical path. The complex amplitude of the beam is retrieved from the images by the minimization of a Maximum a Posteriori error metric between the images and a model of the beam propagation. The analytical formalism of the method and its experimental validation are presented. The modulus of the beam is compared to a measurement of the beam profile, the phase of the beam is compared to a conventional phase diversity estimate. The precision of the experimental measurements is investigated by numerical simulations.
Mimicking an amplitude damping channel for Laguerre Gaussian Modes
CSIR Research Space (South Africa)
Dudley, Angela L
2010-10-01
Full Text Available An amplitude damping channel for Laguerre-Gaussian (LG) modes is presented. Experimentally the action of the channel on LG modes is in good agreement with that predicted theoretically....
Singularities in four-body final-state amplitudes
International Nuclear Information System (INIS)
Adhikari, S.K.
1978-01-01
Like three-body amplitudes, four-body amplitudes have subenergy threshold singularities over and above total-energy singularities. In the four-body problem we encounter a new type of subenergy singularity besides the usual two- and three-body subenergy threshold singularities. This singularity will be referred to as ''independent-pair threshold singularity'' and involves pair-subenergy threshold singularities in each of the two independent pair subenergies in four-body final states. We also study the particularly interesting case of resonant two- and three-body interactions in the four-body isobar model and the rapid (singular) dependence of the isobar amplitudes they generate in the four-body phase space. All these singularities are analyzed in the multiple-scattering formalism and it is shown that they arise from the ''next-to-last'' rescattering and hence may be represented correctly by an approximate amplitude which has that rescattering
Bessel–Gauss resonator with internal amplitude filter
CSIR Research Space (South Africa)
Litvin, IA
2008-05-01
Full Text Available The authors investigate a conventional resonator configuration, using only spherical curvature optical elements, for the generation of Bessel–Gauss beams. This is achieved through the deployment of a suitable amplitude filter at a Fourier plane...
Analytic computations of massive one-loop amplitudes
International Nuclear Information System (INIS)
Badger, Simon; Yundin, Valery; Sattler, Ralf
2010-06-01
We show some new applications of on-shell methods to calculate compact helicity amplitudes for t anti t production through gluon fusion. The rational and mass renormalisation contributions are extracted from two independent Feynman diagram based approaches. (orig.)
Nonlinear Saturation Amplitude in Classical Planar Richtmyer–Meshkov Instability
International Nuclear Information System (INIS)
Liu Wan-Hai; Jiang Hong-Bin; Ma Wen-Fang; Wang Xiang
2016-01-01
The classical planar Richtmyer–Meshkov instability (RMI) at a fluid interface supported by a constant pressure is investigated by a formal perturbation expansion up to the third order, and then according to definition of nonlinear saturation amplitude (NSA) in Rayleigh–Taylor instability (RTI), the NSA in planar RMI is obtained explicitly. It is found that the NSA in planar RMI is affected by the initial perturbation wavelength and the initial amplitude of the interface, while the effect of the initial amplitude of the interface on the NSA is less than that of the initial perturbation wavelength. Without marginal influence of the initial amplitude, the NSA increases linearly with wavelength. The NSA normalized by the wavelength in planar RMI is about 0.11, larger than that corresponding to RTI. (paper)
Euclidean to Minkowski Bethe-Salpeter amplitude and observables
Energy Technology Data Exchange (ETDEWEB)
Carbonell, J. [Universite Paris-Sud, IN2P3-CNRS, Institut de Physique Nucleaire, Orsay Cedex (France); Frederico, T. [Instituto Tecnologico de Aeronautica, DCTA, Sao Jose dos Campos (Brazil); Karmanov, V.A. [Lebedev Physical Institute, Moscow (Russian Federation)
2017-01-15
We propose a method to reconstruct the Bethe-Salpeter amplitude in Minkowski space given the Euclidean Bethe-Salpeter amplitude - or alternatively the light-front wave function - as input. The method is based on the numerical inversion of the Nakanishi integral representation and computing the corresponding weight function. This inversion procedure is, in general, rather unstable, and we propose several ways to considerably reduce the instabilities. In terms of the Nakanishi weight function, one can easily compute the BS amplitude, the LF wave function and the electromagnetic form factor. The latter ones are very stable in spite of residual instabilities in the weight function. This procedure allows both, to continue the Euclidean BS solution in the Minkowski space and to obtain a BS amplitude from a LF wave function. (orig.)
The zerology of kaon-nucleon forward scattering amplitudes
International Nuclear Information System (INIS)
Dumbrajs, O.
1981-01-01
It has been realized for a long time that zeros of the forward kaon-nucleon scattering amplitudes are useful in correlating different low and high-energy scattering parameters and in providing a consistency test of available data. The simplest possibility of exploring zeros is to evaluate the ordinary dispersion relations in the complex energy plane. The more natural way of bringing zeros of amplitudes into play is to consider either one of the more sophisticated forms of dispersion relations: i) phase dispersion relations, ii) inverse-amplitude dispersion relations, iii) logarithmic dispersion relations, or to apply the maximum modulus theorem and a factorization theorem. The author concentrates on the use of logarithmic dispersion relations because this approach seems to be the most convenient one for future extensions to nonforward scattering data analyses based on the zeros of the amplitude. (Auth.)
Aging increases compensatory saccade amplitude in the video head impulse test
Directory of Open Access Journals (Sweden)
Eric R Anson
2016-07-01
Full Text Available Objective: Rotational vestibular function declines with age resulting in saccades as a compensatory mechanism to improve impaired gaze stability. Small reductions in rotational vestibulo-ocular reflex (VOR gain that would be considered clinically normal have been associated with compensatory saccades. We evaluated whether compensatory saccade characteristics varied as a function of age, independent of semicircular canal function as quantified by VOR gain.Methods: Horizontal VOR gain was measured in 243 participants age 27-93 from the Baltimore Longitudinal Study of Aging using video head impulse testing (HIT. Latency and amplitude of the first saccade (either covert – occurring during head impulse, or overt – occurring following head impulse were measured for head impulses with compensatory saccades (n = 2230 head impulses. The relationship between age and saccade latency, as well as the relationship between age and saccade amplitude, were evaluated using regression analyses adjusting for VOR gain, gender, and race.Results: Older adults (mean age 75.9 made significantly larger compensatory saccades relative to younger adults (mean age 45.0. In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory covert saccade (β = 0.015, p = 0.008. In analyses adjusted for VOR gain, there was a significant association between age and amplitude of the first compensatory overt saccade (β = 0.02, p < 0.001. Compensatory saccade latencies did not vary significantly by age. Conclusions: We observed that aging increases the compensatory catch-up saccade amplitude in healthy adults after controlling for VOR gain. Size of compensatory saccades may be useful in addition to VOR gain for characterizing vestibular function in aging adults.
The method of contour rotations and the three particle amplitudes
International Nuclear Information System (INIS)
Brinati, J.R.
1980-01-01
The application of the method of contour rotations to the solution of the Faddeev-Lovelace equations and the calculation of the break-up and stripping amplitudes in a system of three distinct particles is reviewed. A relationship between the masses of the particles is obtained, which permits the break-up amplitude to be calculated from a single iteration of the final integral equation. (Author) [pt
Cosmological constraints on the amplitude of relic gravitational waves
International Nuclear Information System (INIS)
Novosyadlij, B.; Apunevich, S.
2005-01-01
The evolution of the amplitude of relic gravitational waves (RGW) generated in early Universe has been analyzed. The analytical approximation is presented for angular power spectrum of cosmic microwave background anisotropies caused by gravitational waves through Sachs-Wolfe effect. The estimate of the most probable value for this amplitude was obtained on the basis of observation data on cosmic microwave background anisotropies from COBE, WMAP and BOOMERanG experiments along with large-scale structure observations
Multiple pole in the electron--hydrogen-atom scattering amplitude
International Nuclear Information System (INIS)
Amusia, M.Y.; Kuchiev, M.Y.
1982-01-01
It is demonstrated that the amplitude for electron--hydrogen-atom forward scattering has the third-order pole at the point E = -13.6 eV, E being the energy of the incident electron. The coefficients which characterize the pole are calculated exactly. The invalidity of the Born approximation is proved. The contribution of the pole singularity to the dispersion relation for the scattering amplitude is discussed
Examining the time dependence of DAMA's modulation amplitude
Kelso, Chris; Savage, Christopher; Sandick, Pearl; Freese, Katherine; Gondolo, Paolo
2018-03-01
If dark matter is composed of weakly interacting particles, Earth's orbital motion may induce a small annual variation in the rate at which these particles interact in a terrestrial detector. The DAMA collaboration has identified at a 9.3σ confidence level such an annual modulation in their event rate over two detector iterations, DAMA/NaI and DAMA/LIBRA, each with ˜ 7 years of observations. This data is well fit by a constant modulation amplitude for the two iterations of the experiment. We statistically examine the time dependence of the modulation amplitudes, which "by eye" appear to be decreasing with time in certain energy ranges. We perform a chi-squared goodness of fit test of the average modulation amplitudes measured by the two detector iterations which rejects the hypothesis of a consistent modulation amplitude at greater than 80, 96, and 99.6% for the 2-4, 2-5 and 2-6 keVee energy ranges, respectively. We also find that among the 14 annual cycles there are three ≳ 3σ departures from the average in our estimated data in the 5-6 keVee energy range. In addition, we examined several phenomenological models for the time dependence of the modulation amplitude. Using a maximum likelihood test, we find that descriptions of the modulation amplitude as decreasing with time are preferred over a constant modulation amplitude at anywhere between 1σ and 3σ , depending on the phenomenological model for the time dependence and the signal energy range considered. A time dependent modulation amplitude is not expected for a dark matter signal, at least for dark matter halo morphologies consistent with the DAMA signal. New data from DAMA/LIBRA-phase2 will certainly aid in determining whether any apparent time dependence is a real effect or a statistical fluctuation.
Factorization of the six-particle multi-Regge amplitude
International Nuclear Information System (INIS)
Moen, I.O.
1975-01-01
It is shown that factorization of the multi-Regge contribution to the six-particle amplitude follows from the complex-helicity-plane structure, the Steinmann relations, and extended unitarity. The six-particle multi-Regge amplitude also satisfies some new discontinuity relations which are interpreted as resulting from the interplay of singularities required by the Gram-determinant constraint in four-dimensional space-time
Controlling quantum interference in phase space with amplitude
Xue, Yinghong; Li, Tingyu; Kasai, Katsuyuki; Okada-Shudo, Yoshiko; Watanabe, Masayoshi; Zhang, Yun
2017-01-01
We experimentally show a quantum interference in phase space by interrogating photon number probabilities (n?=?2, 3, and 4) of a displaced squeezed state, which is generated by an optical parametric amplifier and whose displacement is controlled by amplitude of injected coherent light. It is found that the probabilities exhibit oscillations of interference effect depending upon the amplitude of the controlling light field. This phenomenon is attributed to quantum interference in phase space a...
Fatigue life assessment under multiaxial variable amplitude loading
International Nuclear Information System (INIS)
Morilhat, P.; Kenmeugne, B.; Vidal-Salle, E.; Robert, J.L.
1996-06-01
A variable amplitude multiaxial fatigue life prediction method is presented in this paper. It is based on a stress as input data are the stress tensor histories which may be calculated by FEM analysis or measured directly on the structure during the service loading. The different steps of he method are first presented then its experimental validation is realized for log and finite fatigue lives through biaxial variable amplitude loading tests using cruciform steel samples. (authors). 9 refs., 7 figs
Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids
Adler, Laszlo; Cantrell, John H.; Yost, William T.
2016-01-01
Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.
Mapping Pn amplitude spreading and attenuation in Asia
Energy Technology Data Exchange (ETDEWEB)
Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory
2010-12-06
Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.
Separation of musical instruments based on amplitude and frequency comodulation
Jacobson, Barry D.; Cauwenberghs, Gert; Quatieri, Thomas F.
2002-05-01
In previous work, amplitude comodulation was investigated as a basis for monaural source separation. Amplitude comodulation refers to similarities in amplitude envelopes of individual spectral components emitted by particular types of sources. In many types of musical instruments, amplitudes of all resonant modes rise/fall, and start/stop together during the course of normal playing. We found that under certain well-defined conditions, a mixture of constant frequency, amplitude comodulated sources can unambiguously be decomposed into its constituents on the basis of these similarities. In this work, system performance was improved by relaxing the constant frequency requirement. String instruments, for example, which are normally played with vibrato, are both amplitude and frequency comodulated sources, and could not be properly tracked under the constant frequency assumption upon which our original algorithm was based. Frequency comodulation refers to similarities in frequency variations of individual harmonics emitted by these types of sources. The analytical difficulty is in defining a representation of the source which properly tracks frequency varying components. A simple, fixed filter bank can only track an individual spectral component for the duration in which it is within the passband of one of the filters. Alternatives are therefore explored which are amenable to real-time implementation.
An Analysis of Fundamental Mode Surface Wave Amplitude Measurements
Schardong, L.; Ferreira, A. M.; van Heijst, H. J.; Ritsema, J.
2014-12-01
Seismic tomography is a powerful tool to decipher the Earth's interior structure at various scales. Traveltimes of seismic waves are widely used to build velocity models, whereas amplitudes are still only seldomly accounted for. This mainly results from our limited ability to separate the various physical effects responsible for observed amplitude variations, such as focussing/defocussing, scattering and source effects. We present new measurements from 50 global earthquakes of fundamental-mode Rayleigh and Love wave amplitude anomalies measured in the period range 35-275 seconds using two different schemes: (i) a standard time-domain amplitude power ratio technique; and (ii) a mode-branch stripping scheme. For minor-arc data, we observe amplitude anomalies with respect to PREM in the range of 0-4, for which the two measurement techniques show a very good overall agreement. We present here a statistical analysis and comparison of these datasets, as well as comparisons with theoretical calculations for a variety of 3-D Earth models. We assess the geographical coherency of the measurements, and investigate the impact of source, path and receiver effects on surface wave amplitudes, as well as their variations with frequency in a wider range than previously studied.
A proposed physical analog for a quantum probability amplitude
Boyd, Jeffrey
What is the physical analog of a probability amplitude? All quantum mathematics, including quantum information, is built on amplitudes. Every other science uses probabilities; QM alone uses their square root. Why? This question has been asked for a century, but no one previously has proposed an answer. We will present cylindrical helices moving toward a particle source, which particles follow backwards. Consider Feynman's book QED. He speaks of amplitudes moving through space like the hand of a spinning clock. His hand is a complex vector. It traces a cylindrical helix in Cartesian space. The Theory of Elementary Waves changes direction so Feynman's clock faces move toward the particle source. Particles follow amplitudes (quantum waves) backwards. This contradicts wave particle duality. We will present empirical evidence that wave particle duality is wrong about the direction of particles versus waves. This involves a paradigm shift; which are always controversial. We believe that our model is the ONLY proposal ever made for the physical foundations of probability amplitudes. We will show that our ``probability amplitudes'' in physical nature form a Hilbert vector space with adjoints, an inner product and support both linear algebra and Dirac notation.
Energy Technology Data Exchange (ETDEWEB)
Andrew H. Stern
2004-12-20
The aim of this research project was to develop a preliminary ''conceptual design'' for a radically smaller, highly adaptive and application-flexible underground coal mining machine, for performing non-production utility work and/or also undertake limited production mining for the recovery of reserves that would otherwise be lost. Whereas historically, mining philosophies have reflected a shift to increasing larger mechanized systems [such as the continuous miner (CM)], specific mining operations that do not benefit from the economy of the large mining equipment are often ignored or addressed with significant inefficiencies. Developing this prototype concept will create a new class of equipment that can provide opportunities to re-think the very structure of the mining system across a broad range of possibilities, not able to be met by existing machinery. The approach involved pooling the collective input from mining professionals, using a structured listing of desired inputs in the form of a questionnaire, which was used to define the range of desired design specifications. From these inputs, a conceptual specification was blended, by the author, to embody the general concurrence of mission concepts for this machine.
Yip, Wilson; Wiessing, Katy R; Budgett, Stephanie; Poppitt, Sally D
2013-10-01
The aim of the study was to determine whether plate size affects ad libitum energy intake (EI) at a buffet-style lunch in overweight, yet unrestrained women. Twenty overweight/obese (BMI=25-40 kg/m(2)) women attended two study visits, and were randomly assigned to small (19.5 cm) or large (26.5 cm) diameter plate size at a free choice lunch meal. At 9 am participants were given a small (0.5 MJ) breakfast, followed at 12 noon by the lunch meal from which they ate ad lib until comfortably full. Mean (SEM) EI at lunch was 3975 (239)kJ and 3901 (249) kJ respectively for small and large plate size. There was no detectable difference in EI between the two plate sizes (P>0.05). When in a raised state of hunger and offered a palatable buffet meal, altering the diameter of the dining plate onto which food was self-served did not significantly alter ad lib EI. We conclude there was no evidence that a smaller plate suppressed EI in a group of unrestrained, overweight women encouraged to eat to appetite from a wide choice of items. Whether plate size is a useful cue for portion size, and hence control of EI, in individuals actively restricting intake however remains possible, and requires investigation. Copyright © 2013 Elsevier Ltd. All rights reserved.
Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats
Andino-Pavlovsky, Victoria; Souza, Annie C.; Scheffer-Teixeira, Robson; Tort, Adriano B. L.; Etchenique, Roberto; Ribeiro, Sidarta
2017-01-01
Dopamine release and phase-amplitude cross-frequency coupling (CFC) have independently been implicated in prefrontal cortex (PFC) functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP) recorded from the medial PFC (mPFC) of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC. PMID:28536507
Constraining lowermost mantle structure with PcP/P amplitude ratios from large aperture arrays
Ventosa, S.; Romanowicz, B. A.
2015-12-01
Observations of weak short-period teleseismic body waves help to resolve lowermost mantle structure at short wavelengths, which is essential for understanding mantle dynamics and the interactions between the mantle and core. Their limited amount and uneven distribution are however major obstacles to solve for volumetric structure of the D" region, topography of the core-mantle boundary (CMB) and D" discontinuity, and the trade-offs among them. While PcP-P differential travel times provide important information, there are trade-offs between velocity structure and core-mantle boundary topography, which PcP/P amplitude ratios can help resolve, as long as lateral variations in attenuation and biases due to focusing are small or can be corrected for. Dense broadband seismic networks help to improve signal-to-noise ratio (SNR) of the target phases and signal-to-interference ratio (SIR) of other mantle phases when the slowness difference is large enough. To improve SIR and SNR of teleseismic PcP data, we have introduced the slant-stacklet transform to define coherent-guided filters able to separate and enhance signals according to their slowness, time of arrival and frequency content. We thus obtain optimal PcP/P amplitude ratios in the least-square sense using two short sliding windows to match the P signal with a candidate PcP signal. This method allows us to dramatically increase the amount of high-quality observations of short-period PcP/P amplitude ratios by allowing for smaller events and wider epicentral distance and depth ranges.We present the results of measurement of PcP/P amplitude ratios, sampling regions around the Pacific using dense arrays in North America and Japan. We observe that short-period P waves traveling through slabs are strongly affected by focusing, in agreement with the bias we have observed and corrected for due to mantle heterogeneities on PcP-P travel time differences. In Central America, this bias is by far the stronger anomaly we observe
Directory of Open Access Journals (Sweden)
Blick, Theo
2004-11-01
Full Text Available book review: Harvey Mark S. (2003: Catalogue of the smaller arachnid orders of the world: Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei and Solifugae. Includes checklists for Europe of: Amblypygi, Uropygi, Schizomida, Palpigradi, Solifugae.
The open superstring 6-point amplitude with manifest symmetries
International Nuclear Information System (INIS)
Barreiro, Luiz Antonio; Medina, Ricardo; Stieberger, Stephan
2011-01-01
Full text: The general tree level amplitude for massless bosons states of open superstrings has been known for a long time ago. It is clear how to obtain this general formula using vertex operators in the Ramond-Neveu-Schwarz formalism. From the beginning of the eighties the explicit expression for this formula has been known in the case of 3 and 4-point amplitudes. In that decade an attempt (with partial success) was done, by Kitazawa, to obtain the corresponding 5-point amplitude. Only in 2002 a complete and correct expression for this amplitude was obtained. Its low energy expansion was compared to the corresponding one from the low energy effective Lagrangian of the open superstring, finding a perfect match. A few years later, in 2005, it was realized that the 5-point formula could be written in a very much compact form, as a sum of two terms: each of them consisting of a momentum factor and a kinematic expression. This constituted a generalization of the 4-point amplitude case, which had been known to be cast in only one momentum factor multiplied by one kinematic expression. For this simplification to happen, known symmetries of the (tree level) scattering amplitudes were implemented in a manifest form. These symmetries are (on-shell) gauge symmetry, cyclic symmetry and twisting symmetry (or world sheet parity). In the recent years it has been realized that the N-point amplitude can be written as a sum of (N - 3)! terms (where N > 3). This result not only agrees with the 3, 4 and 5-point results, but also with the 6-point result which had been obtained by 2005, written as a sum of six terms. The expression that up to now has been obtained for the 6-point amplitude is quite complicated and, besides knowing that it consists of six terms, is not very illuminating. In this work we report on the recent result of writing the 6-point amplitude with gauge, cyclic and twisting symmetries manifest. Not only because of the manifest symmetries this result is important
Wang, Jiali; Byrne, James; Franquiz, Juan; McGoron, Anthony
2007-08-01
develop and validate a PET sorting algorithm based on the respiratory amplitude to correct for abnormal respiratory cycles. using the 4D NCAT phantom model, 3D PET images were simulated in lung and other structures at different times within a respiratory cycle and noise was added. To validate the amplitude binning algorithm, NCAT phantom was used to simulate one case of five different respiratory periods and another case of five respiratory periods alone with five respiratory amplitudes. Comparison was performed for gated and un-gated images and for the new amplitude binning algorithm with the time binning algorithm by calculating the mean number of counts in the ROI (region of interest). an average of 8.87+/-5.10% improvement was reported for total 16 tumors with different tumor sizes and different T/B (tumor to background) ratios using the new sorting algorithm. As both the T/B ratio and tumor size decreases, image degradation due to respiration increases. The greater benefit for smaller diameter tumor and lower T/B ratio indicates a potential improvement in detecting more problematic tumors.
Directory of Open Access Journals (Sweden)
Balla Srinivasa Prasad
2017-02-01
Full Text Available In this paper, a correlation between vibration amplitude and tool wear when in dry turning of AISI 4140 steel using uncoated carbide insert DNMA 432 is analyzed via experiments and finite element simulations. 3D Finite element simulations results are utilized to predict the evolution of cutting forces, vibration displacement amplitudes and tool wear in vibration induced turning. In the present paper, the primary concern is to find the relative vibration and tool wear with the variation of process parameters. These changes lead to accelerated tool wear and even breakage. The cutting forces in the feed direction are also predicted and compared with the experimental trends. A laser Doppler vibrometer is used to detect vibration amplitudes and the usage of Kistler 9272 dynamometer for recording the cutting forces during the cutting process is well demonstrated. A sincere effort is put to investigate the influence of spindle speed, feed rate, depth of cut on vibration amplitude and tool flank wear at different levels of workpiece hardness. Empirical models have been developed using second order polynomial equations for correlating the interaction and higher order influences of various process parameters. Analysis of variance (ANOVA is carried out to identify the significant factors that are affecting the vibration amplitude and tool flank wear. Response surface methodology (RSM is implemented to investigate the progression of flank wear and displacement amplitude based on experimental data. While measuring the displacement amplitude, R-square values for experimental and numerical methods are 98.6 and 97.8. Based on the R-square values of ANOVA it is found that the numerical values show good agreement with the experimental values and are helpful in estimating displacement amplitude. In the case of predicting the tool wear, R-square values were found to be 97.69 and 96.08, respectively for numerical and experimental measures while determining the tool
Energy Technology Data Exchange (ETDEWEB)
Cherkinsky, Alexander, E-mail: acherkin@uga.edu [CENTER FOR APPLIED ISOTOPE STUDIES, University of Georgia, 120 Riverbend Road, Athens, GA 30602 (United States); Ravi Prasad, G.V.; Dvoracek, Doug [CENTER FOR APPLIED ISOTOPE STUDIES, University of Georgia, 120 Riverbend Road, Athens, GA 30602 (United States)
2013-01-15
The center for applied isotope studies has developed a protocol for the measurement of radiocarbon in the range 0.01-0.3 mg of carbon. We analyzed a series of radiocarbon-free and modern standards using the same sample preparation procedure as for unknown samples. We have studied the size dependency of {sup 12}C and {sup 13}C beam currents and {sup 14}C/{sup 13}C ratios from cathodes containing less than 1 mg of carbon. The iron catalyst used for graphite preparation contains some carbon with activity about 60 pMC and the level of contamination varies between batches from the same supplier. The cathodes in the range smaller than 50 {mu}g showed a very significant dependency between current and the sample size. In this range the current increased by about fifteen-fold; between 50 and 100 {mu}g the current increased two-fold. Samples larger than 300 {mu}g have shown negligible current variation. The {sup 14}C/{sup 13}C ratio was significantly affected only for the samples less than 50 {mu}g. Larger samples have shown very little variation in the {sup 14}C/{sup 13}C ratio. For the measurement of ultra-small unknown samples in the range of 10-50 {mu}g, we have found it to be important to use blanks and modern standards with exactly the same amount of carbon, which makes it possible to apply a mass-balanced correction.
Latitudinal amplitude-phase structure of MHD waves: STARE radar observations and modeling
Directory of Open Access Journals (Sweden)
Pilipenko V.
2016-09-01
Full Text Available We have developed a numerical model that yields a steady-state distribution of field components of MHD wave in an inhomogeneous plasma box simulating the realistic magnetosphere. The problem of adequate boundary condition at the ionosphere–magnetosphere interface for coupled MHD mode is considered. To justify the model’s assumptions, we have derived the explicit inequality showing when the ionospheric inductive Hall effect can be neglected upon the consideration of Alfven wave reflection from the ionospheric boundaries. The model predicts a feature of the ULF spatial amplitude/phase distribution that has not been noticed by the field line resonance theory: the existence of a region with opposite phase delays on the source side of the resonance. This theoretical prediction is supported by the amplitude-phase latitudinal structures of Pc5 waves observed by STARE radar and IMAGE magnetometers. A gradual decrease in azimuthal wave number m at smaller L-shells was observed at longitudinally separated radar beams.
Suppression of Subsequent N1m Amplitude When the Masker Frequency is Different from the Signal
Directory of Open Access Journals (Sweden)
Yuka Uratani
2014-01-01
Full Text Available When two tones are presented in a short interval of time, the presentation of the preceding tone (masker suppresses the response evoked by the subsequent tone (signal. To address the processing in forward suppression, we applied 2- and 4-kHz maskers, followed by a 1-kHz signal at varying signal delays (0 to 320 ms and measured the signal-evoked N1m. A two-way analysis of variance revealed a statistically significant effect for signal delay in both masker presentation conditions. The N1m peak amplitude at the signal delay of 320 ms was significantly larger than those of 10, 20, 40, and 80 ms ( p < 0.05. No significant enhancement for the very short signal delay was observed. The results suggest that the enhancement of N1m peak amplitude for short signal delay conditions is maximized when the frequency of the masker is identical to that of the signal.
International Nuclear Information System (INIS)
Bhadelia, R.A.; Bogdan, A.R.; Kaplan, R.F.; Wolpert, S.M.
1997-01-01
Our purpose in this investigation was to explain the heterogeneity in the cerebrospinal fluid (CSF) flow pulsation amplitudes. To this end, we determined the contributions of the cerebral arterial and jugular venous flow pulsations to the amplitude of the CSF pulsation. We examined 21 healthy subjects by cine phase-contrast MRI at the C2-3 disc level to demonstrate the CSF and vascular flows as waveforms. Multiple regression analysis was performed to calculate the contributions of (a) the arterial and venous waveform amplitudes and (b) the delay between the maximum systolic slopes of the arterial and venous waveforms (AV delay), in order to predict the amplitude of the CSF waveform. The contribution of the arterial waveform amplitude was positive (r = 0.61; p 0.003) to the CSF waveform amplitude and that of the venous waveform amplitude was negative (r = -0.50; p = 0.006). Both in combination accounted for 56 % of the variance in predicting the CSF waveform amplitude (p < 0.0006). The contribution of AV delay was not significant. The results show that the variance in the CSF flow pulsation amplitudes can be explained by concurrent evaluation of the CSF and vascular flows. Improvement in the techniques, and controlled experiments, may allow use of CSF flow pulsation amplitudes for clinical applications in the non-invasive assessment of intracranial dynamics by MRI. (orig.). With 3 figs., 2 tabs
Logue, Mark W.; van Rooij, Sanne J.H.; Dennis, Emily L.; Davis, Sarah L.; Hayes, Jasmeet P.; Stevens, Jennifer S.; Densmore, Maria; Haswell, Courtney C.; Ipser, Jonathan; Koch, Saskia B.J.; Korgaonkar, Mayuresh; Lebois, Lauren A.M.; Peverill, Matthew; Baker, Justin T.; Boedhoe, Premika S.W.; Frijling, Jessie L.; Gruber, Staci A.; Harpaz-Rotem, Ilan; Jahanshad, Neda; Koopowitz, Sheri; Levy, Ifat; Nawijn, Laura; O’Connor, Lauren; Olff, Miranda; Salat, David H.; Sheridan, Margaret A.; Spielberg, Jeffrey M.; van Zuiden, Mirjam; Winternitz, Sherry R.; Wolff, Jonathan D.; Wolf, Erika J.; Wang, Xin; Wrocklage, Kristen; Abdallah, Chadi G.; Bryant, Richard A.; Geuze, Elbert; Jovanovic, Tanja; Kaufman, Milissa L.; King, Anthony P.; Krystal, John H.; Lagopoulos, Jim; Bennett, Maxwell; Lanius, Ruth; Liberzon, Israel; McGlinchey, Regina E.; McLaughlin, Katie A.; Milberg, William P.; Miller, Mark W.; Ressler, Kerry J.; Veltman, Dick J.; Stein, Dan J.; Thomaes, Kathleen; Thompson, Paul M.; Morey, Rajendra A.
2018-01-01
BACKGROUND Many studies report smaller hippocampal and amygdala volumes in posttraumatic stress disorder (PTSD), but findings have not always been consistent. Here, we present the results of a large-scale neuroimaging consortium study on PTSD conducted by the Psychiatric Genomics Consortium (PGC)–Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) PTSD Working Group. METHODS We analyzed neuroimaging and clinical data from 1868 subjects (794 PTSD patients) contributed by 16 cohorts, representing the largest neuroimaging study of PTSD to date. We assessed the volumes of eight subcortical structures (nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus, and lateral ventricle). We used a standardized image-analysis and quality-control pipeline established by the ENIGMA consortium. RESULTS In a meta-analysis of all samples, we found significantly smaller hippocampi in subjects with current PTSD compared with trauma-exposed control subjects (Cohen’s d = −0.17, p = .00054), and smaller amygdalae (d = −0.11, p = .025), although the amygdala finding did not survive a significance level that was Bonferroni corrected for multiple subcortical region comparisons (p < .0063). CONCLUSIONS Our study is not subject to the biases of meta-analyses of published data, and it represents an important milestone in an ongoing collaborative effort to examine the neurobiological underpinnings of PTSD and the brain’s response to trauma. PMID:29217296
Zhang, Huiping; Shi, Qiusheng; Gu, Jiying; Jiang, Luying; Bai, Min; Liu, Long; Wu, Ying; Du, Lianfang
2014-02-01
This study aimed to investigate the value of sonographic features including Virtual Touch tissue quantification (VTQ; Siemens Medical Solutions, Mountain View, CA) for differentiating benign and malignant thyroid nodules smaller than 10 mm. Seventy-one thyroid nodules smaller than 10 mm with pathologic diagnoses were included in this study. The conventional sonographic features and quantitative elasticity features (VTQ) were observed and compared between benign and malignant nodules. There were 39 benign and 32 malignant nodules according to histopathologic examination. When compared with benign nodules, malignant nodules were more frequently taller than wide, poorly defined, and markedly hypoechoic (P benign and malignant nodules. The VTQ value for malignant nodules (mean ± SD 3.260 ± 0.725 m/s) was significantly higher than that of benign ones (2.108 ± 0.455 m/s; P benign and malignant thyroid nodules smaller than 10 mm. When VTQ was combined with B-mode sonographic features, the sensitivity was improved significantly.
Logue, Mark W; van Rooij, Sanne J H; Dennis, Emily L; Davis, Sarah L; Hayes, Jasmeet P; Stevens, Jennifer S; Densmore, Maria; Haswell, Courtney C; Ipser, Jonathan; Koch, Saskia B J; Korgaonkar, Mayuresh; Lebois, Lauren A M; Peverill, Matthew; Baker, Justin T; Boedhoe, Premika S W; Frijling, Jessie L; Gruber, Staci A; Harpaz-Rotem, Ilan; Jahanshad, Neda; Koopowitz, Sheri; Levy, Ifat; Nawijn, Laura; O'Connor, Lauren; Olff, Miranda; Salat, David H; Sheridan, Margaret A; Spielberg, Jeffrey M; van Zuiden, Mirjam; Winternitz, Sherry R; Wolff, Jonathan D; Wolf, Erika J; Wang, Xin; Wrocklage, Kristen; Abdallah, Chadi G; Bryant, Richard A; Geuze, Elbert; Jovanovic, Tanja; Kaufman, Milissa L; King, Anthony P; Krystal, John H; Lagopoulos, Jim; Bennett, Maxwell; Lanius, Ruth; Liberzon, Israel; McGlinchey, Regina E; McLaughlin, Katie A; Milberg, William P; Miller, Mark W; Ressler, Kerry J; Veltman, Dick J; Stein, Dan J; Thomaes, Kathleen; Thompson, Paul M; Morey, Rajendra A
2018-02-01
Many studies report smaller hippocampal and amygdala volumes in posttraumatic stress disorder (PTSD), but findings have not always been consistent. Here, we present the results of a large-scale neuroimaging consortium study on PTSD conducted by the Psychiatric Genomics Consortium (PGC)-Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) PTSD Working Group. We analyzed neuroimaging and clinical data from 1868 subjects (794 PTSD patients) contributed by 16 cohorts, representing the largest neuroimaging study of PTSD to date. We assessed the volumes of eight subcortical structures (nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, thalamus, and lateral ventricle). We used a standardized image-analysis and quality-control pipeline established by the ENIGMA consortium. In a meta-analysis of all samples, we found significantly smaller hippocampi in subjects with current PTSD compared with trauma-exposed control subjects (Cohen's d = -0.17, p = .00054), and smaller amygdalae (d = -0.11, p = .025), although the amygdala finding did not survive a significance level that was Bonferroni corrected for multiple subcortical region comparisons (p < .0063). Our study is not subject to the biases of meta-analyses of published data, and it represents an important milestone in an ongoing collaborative effort to examine the neurobiological underpinnings of PTSD and the brain's response to trauma. Published by Elsevier Inc.
LENUS (Irish Health Repository)
Whelan, R
2012-02-01
OBJECTIVE: To quantify latency, amplitude and topographical differences in event-related potential (ERP) components between multiple sclerosis (MS) patients and controls and to compare ERP findings with results from the paced auditory serial addition test (PASAT). METHODS: Fifty-four subjects (17 relapsing remitting (RRMS) patients, 16 secondary progressive (SPMS) patients, and 21 controls) completed visual and auditory oddball tasks while data were recorded from 134 EEG channels. Latency and amplitude differences, calculated using composite mean amplitude measures, were tested using an ANOVA. Topographical differences were tested using statistical parametric mapping (SPM). RESULTS: In the visual modality, P2, P3 amplitudes and N2 latency were significantly different across groups. In the auditory modality, P2, N2, and P3 latencies and N1 amplitude were significantly different across groups. There were no significant differences between RRMS and SPMS patients on any ERP component. There were topographical differences between MS patients and controls for both early and late components for the visual modality, but only in the early components for the auditory modality. PASAT score correlated significantly with auditory P3 latency for MS patients. CONCLUSIONS: There were significant ERP differences between MS patients and controls. SIGNIFICANCE: The present study indicated that both early sensory and later cognitive ERP components are impaired in MS patients relative to controls.
Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li
2016-01-01
Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.
Directory of Open Access Journals (Sweden)
Mo-Zhu Wang
Full Text Available Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.
Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li
2016-01-01
Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions. PMID:26735689
2-vertex Lorentzian spin foam amplitudes for dipole transitions
Sarno, Giorgio; Speziale, Simone; Stagno, Gabriele V.
2018-04-01
We compute transition amplitudes between two spin networks with dipole graphs, using the Lorentzian EPRL model with up to two (non-simplicial) vertices. We find power-law decreasing amplitudes in the large spin limit, decreasing faster as the complexity of the foam increases. There are no oscillations nor asymptotic Regge actions at the order considered, nonetheless the amplitudes still induce non-trivial correlations. Spin correlations between the two dipoles appear only when one internal face is present in the foam. We compute them within a mini-superspace description, finding positive correlations, decreasing in value with the Immirzi parameter. The paper also provides an explicit guide to computing Lorentzian amplitudes using the factorisation property of SL(2,C) Clebsch-Gordan coefficients in terms of SU(2) ones. We discuss some of the difficulties of non-simplicial foams, and provide a specific criterion to partially limit the proliferation of diagrams. We systematically compare the results with the simplified EPRLs model, much faster to evaluate, to learn evidence on when it provides reliable approximations of the full amplitudes. Finally, we comment on implications of our results for the physics of non-simplicial spin foams and their resummation.
Damage accumulation of bovine bone under variable amplitude loads
Directory of Open Access Journals (Sweden)
Abbey M. Campbell
2016-12-01
Full Text Available Stress fractures, a painful injury, are caused by excessive fatigue in bone. This study on damage accumulation in bone sought to determine if the Palmgren-Miner rule (PMR, a well-known linear damage accumulation hypothesis, is predictive of fatigue failure in bone. An electromagnetic shaker apparatus was constructed to conduct cyclic and variable amplitude tests on bovine bone specimens. Three distinct damage regimes were observed following fracture. Fractures due to a low cyclic amplitude loading appeared ductile (4000 μϵ, brittle due to high cyclic amplitude loading (>9000 μϵ, and a combination of ductile and brittle from mid-range cyclic amplitude loading (6500 –6750 μϵ. Brittle and ductile fracture mechanisms were isolated and mixed, in a controlled way, into variable amplitude loading tests. PMR predictions of cycles to failure consistently over-predicted fatigue life when mixing isolated fracture mechanisms. However, PMR was not proven ineffective when used with a single damage mechanism. Keywords: Bone fatigue, Bone fracture, Health system monitoring, Failure prediction
Study of inelastic decay of amplitudes in 49V
International Nuclear Information System (INIS)
Chou, B.H.
1980-01-01
Inelastic decay amplitudes from d-wave resonances in 49 V were obtained for 80 resonances in the proton energy range 2.2 to 3.1 MeV. With the 3 MV Van de Graaff accelerator and high resolution system at the Triangle Universities Nuclear Laboratory, an overall resolution of 350 eV was obtained. The experiment consisted of measurements of the angular distributions of the inelastically scattered protons and the subsequent deexcitation gamma rays. Forty five resonances were assigned J/sup π/ = 5/2 + , while thirty five resonances were assigned 3/2 + . The magnitudes of three inelastic decay amplitudes and the relative signs between these three amplitudes were determined. Large amplitude correlations were observed; the data are in the striking disagreement with the extreme statistical model. The present results provide the first explicit test of the multivariate reduced width amplitude distribution of Krieger and Porter; the agreement is excellent. The physical origin of these channel correlations has not yet been explained
Conformal amplitude hierarchy and the Poincaré disk
Shimada, Hirohiko
2018-02-01
The amplitude for the singlet channels in the 4-point function of the fundamental field in the conformal field theory of the 2d O(n) model is studied as a function of n. For a generic value of n, the 4-point function has infinitely many amplitudes, whose landscape can be very spiky as the higher amplitude changes its sign many times at the simple poles, which generalize the unique pole of the energy operator amplitude at n = 0. In the stadard parameterization of n by angle in unit of π, we find that the zeros and poles happen at the rational angles, forming a hierarchical tree structure inherent in the Poincaré disk. Some relation between the amplitude and the Farey path, a piecewise geodesic that visits these zeros and poles, is suggested. In this hierarchy, the symmetry of the congruence subgroup Γ(2) of SL(2, ℤ) naturally arises from the two clearly distinct even/odd classes of the rational angles, in which one respectively gets the truncated operator algebras and the logarithmic 4-point functions.
DEFF Research Database (Denmark)
Frølich, Simon; Sørensen, Henning Osholm; Hakim, Sepideh Sadat
2015-01-01
The growth and nucleation of biominerals are directed and affected by associated biological molecules. In this paper, we investigate the influence of occluded biomolecules on biogenic calcite from the coccolithophorid Pleurochrysis carterae and from chalk, a rock composed predominantly of fossil....... Two heating cycles allow us to differentiate the effects of thermal agitation and organic molecules. Single peak analysis and Rietveld refinement were combined to show significant differences resulting from the occluded biomolecules on the mineral phase in biogenic calcite in the mollusk shell...
A Smaller Percent of Hispanic Children Have Special Health Care Needs: Is that Possible?
Waldman, H Barry; Wong, Allen; Rojas, Jorge E; Perlman, Steven P
The results from latest study of children with special health care needs indicate at the national and state levels that (except for Asian children) the proportion of Hispanic children with special needs is less than for other child populations. A review of a series of associated factors raises questions of the validity of these general national and state findings. The significant projected increases in the Hispanic population during the next decades points to the necessity of reconsidering the recent survey findings in light of what could be continued increases in the numbers of youngsters with special health care needs and the evolving family cultural adaptation, education and employment opportunities.
Extracorporeal shockwave lithotripsy for lower pole calculi smaller than one centimeter
Directory of Open Access Journals (Sweden)
Christian Chaussy
2008-01-01
When complete stone-free status is the primary goal , follow-up examinations with new radiological technologies like spiral CT show that the stone-free rate of ESWL and endoscopically treated patients (RIRS does not differ significantly. However, in comparison to endoscopic stone removal, shockwave therapy is noninvasive, anesthesia-free and can be performed in an outpatient setup. Therefore, ESWL remains the first choice option for the treatment of lower caliceal stones up to 1 cm. The patient will definitely favour this procedure.
ON MEASURING AMPLITUDES AND PERIODS OF PHYSICAL PENDULUM MICRO-SWINGS WITH ROLLING-CONTACT BEARING
Directory of Open Access Journals (Sweden)
N. N. Riznookaya
2011-01-01
Full Text Available The paper considers a method and an instrument for measuring amplitudes and periods of physical pendulum oscillations with rolling-contact bearing in the regime of micro-swings when the oscillation amplitude is significantly less of an elastic contact angle. It has been established that the main factors limiting a measuring accuracy are noises of the measuring circuit, base vibration and analog-digital conversion. A new measuring methodology based on original algorithms of data processing and application of the well-known methods for statistic processing of a measuring signal is proposed in the paper. The paper contains error estimations for measuring oscillation amplitudes justified by discreteness of a signal conversion in a photoelectric receptor and also by the influence of measuring circuit noise. The paper reveals that the applied methodologies make it possible to ensure measuring of amplitudes with an error of 0.2 second of arc and measuring of a period with an error of 10–4 s. The original measuring instrument including mechanical and optical devices and also an electric circuit of optical-to-electrical measuring signal conversion is described in the paper.
Quantum correlation versus Bell-inequality violation under the amplitude damping channel
Energy Technology Data Exchange (ETDEWEB)
Ma, WenChao; Xu, Shuai; Shi, Jiadong; Ye, Liu, E-mail: yeliu@ahu.edu.cn
2015-11-06
We investigate the quantum correlations including quantum discord and entanglement under the amplitude damping channel. Our analysis results indicate that although the entanglement of initial state is degraded due to decoherence, the distribution trend of entanglement is not to be affected. Moreover, we find that the survival time for entanglement is much longer than for the Bell inequality violation, i.e., as time goes on the Bell inequality violation of final state may be not satisfied while the final state still remains entangled. Especially, although quantum entanglement and quantum discord all decrease under the amplitude damping channel, quantum discord (QD) is reduced significantly slower than entanglement. Therefore, the quantum discord is more robust against amplitude damping in comparison to entanglement measures. Furthermore, we also find that there are mixed states having quantum discord higher than that for pure states for a given degree of Bell's inequality violation. This means that the manipulation of nonclassical correlations via a pure state can result in a larger loss of quantum discord than that via a mixed state. - Highlights: • Entanglement distribution trend is not be affected by the decoherent. • The survival time for entanglement is much longer than for the Bell inequality violation. • The quantum discord is more robust against amplitude damping in comparison entanglement measures.
Source of low frequency modulation of ENSO amplitude in a CGCM
Energy Technology Data Exchange (ETDEWEB)
Moon, Byung-Kwon [Chonbuk National University, Division of Science Education/Institute of Science Education, Jeonju (Korea); Yeh, Sang-Wook [Korea Ocean Research and Development Institute, Ansan (Korea); Dewitte, Boris [Laboratoire d' Etude en Geophysique et Oceanographie Spatiale, Toulouse (France); Jhun, Jong-Ghap [Seoul National University, School of Earth and Environmental Sciences, Seoul (Korea); Kang, In-Sik [Seoul National University, Climate Environment System Research Center (CES), Seoul (Korea)
2007-07-15
We study the relationship between changes in equatorial stratification and low frequency El Nino/Southern Oscillation (ENSO) amplitude modulation in a coupled general circulation model (CGCM) that uses an anomaly coupling strategy to prevent climate drifts in the mean state. The stratification is intensified at upper levels in the western and central equatorial Pacific during periods of high ENSO amplitude. Furthermore, changes in equatorial stratification are connected with subsurface temperature anomalies originating from the central south tropical Pacific. The correlation analysis of ocean temperature anomalies against an index for the ENSO modulation supports the hypothesis of the existence of an oceanic ''tunnel'' that connects the south tropical Pacific to the equatorial wave guide. Further analysis of the wind stress projection coefficient onto the oceanic baroclinic modes suggests that the low frequency modulation of ENSO amplitude is associated with a significant contribution of higher-order modes in the western and central equatorial Pacific. In the light of these results, we suggest that, in the CGCM, change in the baroclinic mode energy distribution associated with low frequency ENSO amplitude modulation have its source in the central south tropical Pacific. (orig.)
Motivation modulates the P300 amplitude during brain-computer interface use.
Kleih, S C; Nijboer, F; Halder, S; Kübler, A
2010-07-01
This study examined the effect of motivation as a possible psychological influencing variable on P300 amplitude and performance in a brain-computer interface (BCI) controlled by event-related potentials (ERP). Participants were instructed to copy spell a sentence by attending to cells of a randomly flashing 7*7 matrix. Motivation was manipulated by monetary reward. In two experimental groups participants received 25 (N=11) or 50 (N=11) Euro cent for each correctly selected character; the control group (N=11) was not rewarded. BCI performance was defined as the overall percentage of correctly selected characters (correct response rate=CRR). Participants performed at an average of 99%. At electrode location Cz the P300 amplitude was positively correlated to self-rated motivation. The P300 amplitude of the most motivated participants was significantly higher than that of the least motivated participants. Highly motivated participants were able to communicate correctly faster with the ERP-BCI than less motivated participants. Motivation modulates the P300 amplitude in an ERP-BCI. Motivation may contribute to variance in BCI performance and should be monitored in BCI settings. Copyright 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.
Available pressure amplitude of linear compressor based on phasor triangle model
Duan, C. X.; Jiang, X.; Zhi, X. Q.; You, X. K.; Qiu, L. M.
2017-12-01
The linear compressor for cryocoolers possess the advantages of long-life operation, high efficiency, low vibration and compact structure. It is significant to study the match mechanisms between the compressor and the cold finger, which determines the working efficiency of the cryocooler. However, the output characteristics of linear compressor are complicated since it is affected by many interacting parameters. The existing matching methods are simplified and mainly focus on the compressor efficiency and output acoustic power, while neglecting the important output parameter of pressure amplitude. In this study, a phasor triangle model basing on analyzing the forces of the piston is proposed. It can be used to predict not only the output acoustic power, the efficiency, but also the pressure amplitude of the linear compressor. Calculated results agree well with the measurement results of the experiment. By this phasor triangle model, the theoretical maximum output pressure amplitude of the linear compressor can be calculated simply based on a known charging pressure and operating frequency. Compared with the mechanical and electrical model of the linear compressor, the new model can provide an intuitionistic understanding on the match mechanism with faster computational process. The model can also explain the experimental phenomenon of the proportional relationship between the output pressure amplitude and the piston displacement in experiments. By further model analysis, such phenomenon is confirmed as an expression of the unmatched design of the compressor. The phasor triangle model may provide an alternative method for the compressor design and matching with the cold finger.
External Ear Resonant Amplitude and Frequency of 3-7 Year Old Children
Directory of Open Access Journals (Sweden)
Amir Hossein Zare
2004-06-01
Full Text Available Objective: To measure external ear resonant amplitude and frequency in children (3-7 years old and to compare with adult measures. Method and materials: The external ear resonance peak amplitude and frequency of 63 children 3-7 years old were recorded. All of the children had normal tympanogram and there was no cerumen in external auditory canal. 20 adult of 21-24 years old (10 male , 10 female were selected in order to compare with children that had normal tympanogram. The tests included : 1-otoscopy 2- tympanometry 3-microphone probe tube test. Results: The average of resonance peak frequency for children and adult is 4200 Hz and 3200 Hz , respectively. The resonance frequency of children had significantly diffrence with average of resonance frequency in adults. The average of resonance peak amplitude for children and adult is 17.70 dB and 17.17 dB , respectively. Conclusion: Resonant frequency and amplitude affect the hearing aid prescription and fitting process and calculating insertion gain; so, this measures seem should be considered in children hearing aid fitting.
Heavy collecting induces smaller and deeper Fritillariae Cirrhosae Bulbus in the wild
Directory of Open Access Journals (Sweden)
Xinhui Li
2017-08-01
Full Text Available Fritillariae Cirrhosae Bulbus is a well-known traditional Chine medicinal herb. However, the demand for this herb is leading to over-collection and its decline in the wild. This study aims to investigate the ecological conditions of Fritillaria cirrhosa under the influence of human disturbance, biotic species interactions and climatic conditions. We established a total of 78 plots at 14 sites of F. cirrhosa in its distribution center, the Hengduan Mountains area. At each site, we estimated the abundance of F. cirrhosa at different distances from roads. The diameter and height of F. cirrhosa fruit and bulbs were measured and compared to underground bulb depth. We then analyzed the effects of environmental conditions and human disturbance on the abundance of F. cirrhosa using variance partitioning. We found that (1 abundance of F. cirrhosa and their underground bulb depth showed a significant linear increase with the distance from the main road; (2 the diameter/height of fruits and the diameter/height of fruits/bulbs showed significantly different responses to the human disturbance; (3 the community associates, climate and spatial conditions can explain 58%, 22% and 27%, respectively, of the variance in the F. cirrhosa abundance. These results highlight the fact that human disturbance and biotic factors have a great influence on the survival of F. cirrhosa, even more than climate conditions.
Calculation of hadronic transition amplitudes in charm physics
International Nuclear Information System (INIS)
Klein, Christoph
2011-01-01
Transitions of charmed hadrons are of significant importance, since they provide possibilities to extract the CKM matrix elements V cd and V cs from experimental data as well as interesting channels to search for new physics effects. However, quarks are bound in hadrons, and it is necessary to describe this effect in a reliable way, to study the underlying flavour dynamics. For this, one has to use nonperturbative tools, to determine the corresponding transition amplitudes. The results of such calculations can furthermore be of use, to test the predictions of QCD and to contribute to a deeper understanding of the structure of hadrons. In this thesis two topics are investigated using the method of QCD light-cone sum rules (LCSRs). The first topic consists in the form factors of the semileptonic decays D → πlν l and D → Klν l , for which new results are calculated using up-to-date input values. Since LCSRs are not applicable in the whole range of kinematics, they are extrapolated by the use of appropriate parametrisations and the results agree well with experimental data. The second topic are the transitions of charmed baryons to a nucleon. Here the corresponding transition form factors and in addition the hadronic Λ c D (*) N and Σ c D (*) N coupling constants are calculated - the latter by the consideration of double dispersion relations. These coupling constants are of special interest for the description of hadronic interactions, like open charm production in proton-antiprotoncollisions. Furthermore there appears the problem, that both parity states of a baryon contribute to the considered functional representation, for which a consistent way to separate them is presented. (orig.)
Tidal Amplitude for a Self-gravitating, Compressible Sphere
Hurford, T. A.; Greenberg, R.
2001-11-01
Most modern evaluations of tidal amplitude derive from the approach presented by Love [1]. Love's analysis for a homogeneous sphere assumed an incompressible material, which required introduction of a non-rigorously justified pressure term. We solve the more general case of arbitrary compressibility, which allows for a more straightforward derivation. We find the h2 love number of a body of radius R, density ρ , and surface gravity g to be h2 = \\Bigg[\\frac{{5}/{2}}{1+\\frac{19 \\mu}{2 \\rho g R}}\\Bigg] \\Bigg\\{ \\frac{2 \\rho g R (35+28\\frac{\\mu}{\\lambda}) + 19 \\mu (35+28\\frac{\\mu}{\\lambda})} {2 \\rho g R (35+31\\frac{\\mu}{\\lambda}) + 19 \\mu (35+{490}/{19}\\frac{\\mu}{\\lambda})}\\Bigg\\} λ the Lamé constant. This h2 is the product of Love's expression for h2 (in square brackets) and a ``compressibility-correction'' factor (in \\{\\} brackets). Unlike Love's expression, this result is valid for any degree of compressibility (i.e. any λ ). For the incompressible case (λ -> ∞ ) the correction factor approaches 1, so that h2 matches the classical form given by Love. In reality, of course, materials are not incompressible and the difference between our solution and Love's is significant. Assuming that the elastic terms dominate over the gravitational contribution (i.e. 19 μ /(2 ρ g R) >> 1), our solution can be ~ 7% percent larger than Love's solution for large μ /λ . If the gravity dominates (i.e. 19 μ /(2 ρ g R) John Wiley & Sons, Inc., 1968
Finite amplitude effects on drop levitation for material properties measurement
Ansari Hosseinzadeh, Vahideh; Holt, R. Glynn
2017-05-01
The method of exciting shape oscillation of drops to extract material properties has a long history, which is most often coupled with the technique of acoustic levitation to achieve non-contact manipulation of the drop sample. We revisit this method with application to the inference of bulk shear viscosity and surface tension. The literature is replete with references to a "10% oscillation amplitude" as a sufficient condition for the application of Lamb's analytical expressions for the shape oscillations of viscous liquids. Our results show that even a 10% oscillation amplitude leads to dynamic effects which render Lamb's results inapplicable. By comparison with samples of known viscosity and surface tension, we illustrate the complicating finite-amplitude effects (mode-splitting and excess dissipation associated with vorticity) that can occur and then show that sufficiently small oscillations allow us to recover the correct material properties using Lamb's formula.
Heptagon amplitude in the multi-Regge regime
International Nuclear Information System (INIS)
Bartels, J.
2014-05-01
As we have shown in previous work, the high energy limit of scattering amplitudes in N=4 supersymmetric Yang-Mills theory corresponds to the infrared limit of the 1-dimensional quantum integrable system that solves minimal area problems in AdS 5 . This insight can be developed into a systematic algorithm to compute the strong coupling limit of amplitudes in the multi-Regge regime through the solution of auxiliary Bethe Ansatz equations. We apply this procedure to compute the scattering amplitude for n=7 external gluons in different multi-Regge regions at infinite 't Hooft coupling. Our formulas are remarkably consistent with the expected form of 7-gluon Regge cut contributions in perturbative gauge theory. A full description of the general algorithm and a derivation of results is given in a forthcoming paper.
PASTA - An RF Phase and Amplitude Scan and Tuning Application
Galambos, J; Deibele, C; Henderson, S
2005-01-01
To assist the beam commissioning in the Spallation Neutron Source (SNS) linac, a general purpose RF tuning application has been written to help set RF phase and amplitude. It follows the signature matching procedure described in Ref.* The method involves varying an upstream Rf cavity amplitude and phase settings and comparing the measured downstream beam phase responses to model predictions. The model input for cavity phase and amplitude calibration and for the beam energy are varied to best match observations. This scheme has advantages over other RF tuning techniques of not requiring intercepting devices (e.g. Faraday Cups), and not being restricted to a small linear response regime near the design values. The application developed here is general and can be applied to different RF structure types in the SNS linac. Example applications in the SNS Drift Tube Linac (DTL) and Coupled Cavity Linac (CCL) structures will be shown.
Top Quark Amplitudes with an Anomolous Magnetic Moment
International Nuclear Information System (INIS)
Larkoski, Andrew
2011-01-01
The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with t(bar t) and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.
Top quark amplitudes with an anomalous magnetic moment
International Nuclear Information System (INIS)
Larkoski, Andrew J.; Peskin, Michael E.
2011-01-01
The anomalous magnetic moment of the top quark may be measured during the first run of the LHC at 7 TeV. For these measurements, it will be useful to have available tree amplitudes with tt and arbitrarily many photons and gluons, including both QED and color anomalous magnetic moments. In this paper, we present a method for computing these amplitudes using the Britto-Cachazo-Feng-Witten recursion formula. Because we deal with an effective theory with higher-dimension couplings, there are roadblocks to a direct computation with the Britto-Cachazo-Feng-Witten method. We evade these by using an auxiliary scalar theory to compute a subset of the amplitudes.
Amplitude saturation of MEMS resonators explained by autoparametric resonance
International Nuclear Information System (INIS)
Van der Avoort, C; Bontemps, J J M; Steeneken, P G; Le Phan, K; Van Beek, J T M; Van der Hout, R; Hulshof, J; Fey, R H B
2010-01-01
This paper describes a phenomenon that limits the power handling of MEMS resonators. It is observed that above a certain driving level, the resonance amplitude becomes independent of the driving level. In contrast to previous studies of power handling of MEMS resonators, it is found that this amplitude saturation cannot be explained by nonlinear terms in the spring constant or electrostatic force. Instead we show that the amplitude in our experiments is limited by nonlinear terms in the equation of motion which couple the in-plane length-extensional resonance mode to one or more out-of-plane (OOP) bending modes. We present experimental evidence for the autoparametric excitation of these OOP modes using a vibrometer. The measurements are compared to a model that can be used to predict a power-handling limit for MEMS resonators
Amplitude saturation of MEMS resonators explained by autoparametric resonance
Energy Technology Data Exchange (ETDEWEB)
Van der Avoort, C; Bontemps, J J M; Steeneken, P G; Le Phan, K; Van Beek, J T M [NXP Research, Eindhoven (Netherlands); Van der Hout, R; Hulshof, J [Department of Mathematics, VU University—Faculty of Sciences, De Boelelaan 1081a, 1081 HV Amsterdam (Netherlands); Fey, R H B, E-mail: cas.van.der.avoort@nxp.com [Department of Mechanical Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven (Netherlands)
2010-10-15
This paper describes a phenomenon that limits the power handling of MEMS resonators. It is observed that above a certain driving level, the resonance amplitude becomes independent of the driving level. In contrast to previous studies of power handling of MEMS resonators, it is found that this amplitude saturation cannot be explained by nonlinear terms in the spring constant or electrostatic force. Instead we show that the amplitude in our experiments is limited by nonlinear terms in the equation of motion which couple the in-plane length-extensional resonance mode to one or more out-of-plane (OOP) bending modes. We present experimental evidence for the autoparametric excitation of these OOP modes using a vibrometer. The measurements are compared to a model that can be used to predict a power-handling limit for MEMS resonators.
String amplitudes: from field theories to number theory
CERN. Geneva
2017-01-01
In a variety of recent developments, scattering amplitudes hint at new symmetries of and unexpected connections between physical theories which are otherwise invisible in their conventional description via Feynman diagrams or Lagrangians. Yet, many of these hidden structures are conveniently accessible to string theory where gauge interactions and gravity arise as the low-energy excitations of open and closed strings. In this talk, I will give an intuitive picture of gravity as a double copy of gauge interactions and extend the web of relations to scalar field theories including chiral Lagrangians for Goldstone bosons. The string corrections to gauge and gravity amplitudes beyond their point-particle limit exhibit elegant mathematical structures and offer a convenient laboratory to explore modern number-theoretic concepts in a simple context. As a common theme with Feynman integrals, string amplitudes introduce a variety of periods and special functions including multiple zeta values and polylogarithms, orga...
One-Loop BPS amplitudes as BPS-state sums
Angelantonj, Carlo; Pioline, Boris
2012-01-01
Recently, we introduced a new procedure for computing a class of one-loop BPS-saturated amplitudes in String Theory, which expresses them as a sum of one-loop contributions of all perturbative BPS states in a manifestly T-duality invariant fashion. In this paper, we extend this procedure to all BPS-saturated amplitudes of the form \\int_F \\Gamma_{d+k,d} {\\Phi}, with {\\Phi} being a weak (almost) holomorphic modular form of weight -k/2. We use the fact that any such {\\Phi} can be expressed as a linear combination of certain absolutely convergent Poincar\\'e series, against which the fundamental domain F can be unfolded. The resulting BPS-state sum neatly exhibits the singularities of the amplitude at points of gauge symmetry enhancement, in a chamber-independent fashion. We illustrate our method with concrete examples of interest in heterotic string compactifications.
Expression of relativistic amplitudes in terms of wave functions
International Nuclear Information System (INIS)
Karmanov, V.A.
1978-01-01
The conditions under which relativistic amplitudes may be expressed in terms of the wave functions are analyzed within the framework of the invariant diagram technique which appears on formulation of field theory on the light front. The amplitudes depend on the 4-vector ω which defines the surface of the light front. A rule is formulated for the determination of those values of the 4-vector ω for which the diagram contribution, which cannot be expressed in terms of the wave functions, is minimum. The present investigation is equivalent to a study of the dependence of the amplitudes of the old fashioned perburbation theory in the infinite momentum depending on the direction of the infinite momentum
On expansion of scattering amplitude at large momentum transfers
International Nuclear Information System (INIS)
Edneral, V.F.; Troshin, S.M.; Tyurin, N.E.
1979-01-01
The aim of the paper is to construct an iterative approximation for hadronic scattering amplitude and to search for the related small parameters. The expansion of the amplitude is obtained. A series is derived where the role of the small parameter is played by the quantity dependent on the momentum transfer. The appearance of the small parameter is directly related to the growth of total cross section. For the case g 2 not equal to 0 in the framework of the strong interaction theory model, based on the solution of three-domensional dynamical equation an expression is obtained for scattering amplitude in the form of a series over the quantity decreasing with the growth of momentum transfer
Amplitude and polarization asymmetries in a ring laser
Campbell, L. L.; Buholz, N. E.
1971-01-01
Asymmetric amplitude effects between the oppositely directed traveling waves in a He-Ne ring laser are analyzed both theoretically and experimentally. These effects make it possible to detect angular orientations of an inner-cavity bar with respect to the plane of the ring cavity. The amplitude asymmetries occur when a birefringent bar is placed in the three-mirror ring cavity, and an axial magnetic field is applied to the active medium. A simplified theoretical analysis is performed by using a first order perturbation theory to derive an expression for the polarization of the active medium, and a set of self-consistent equations are derived to predict threshold conditions. Polarization asymmetries between the oppositely directed waves are also predicted. Amplitude asymmetries similar in nature to those predicted at threshold occur when the laser is operating in 12-15 free-running modes, and polarization asymmetry occurs simultaneously.
arXiv New relations for graviton-matter amplitudes
Plefka, Jan
We present new relations for scattering amplitudes of color ordered gluons, massive quarks and scalars minimally coupled to gravity. Tree-level amplitudes of arbitrary matter and gluon multiplicities involving one graviton are reduced to partial amplitudes in QCD or scalar QCD. The obtained relations are a direct generalization of the recently found Einstein-Yang-Mills relations. The proof of the new relation employs a simple diagrammatic argument trading the graviton-matter couplings to an `upgrade' of a gluon coupling with a color-kinematic replacement rule enforced. The use of the Melia-Johansson-Ochirov color basis is a key element of the reduction. We comment on the generalization to multiple gravitons in the single color trace case.
Einstein-Yang-Mills from pure Yang-Mills amplitudes
Energy Technology Data Exchange (ETDEWEB)
Nandan, Dhritiman; Plefka, Jan [Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin,Zum Großen Windkanal 6, D-12489 Berlin (Germany); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,Am Mühlenberg 1, D-14476 Potsdam (Germany); Wen, Congkao [I.N.F.N. Sezione di Roma Tor Vergata,Via della Ricerca Scientifica, 00133 Roma (Italy)
2016-10-14
We present new relations for scattering amplitudes of color ordered gluons and gravitons in Einstein-Yang-Mills theory. Tree-level amplitudes of arbitrary multiplicities and polarizations involving up to three gravitons and up to two color traces are reduced to partial amplitudes of pure Yang-Mills theory. In fact, the double-trace identities apply to Einstein-Yang-Mills extended by a dilaton and a B-field. Our results generalize recent work of Stieberger and Taylor for the single graviton case with a single color trace. As the derivation is made in the dimension-agnostic Cachazo-He-Yuan formalism, our results are valid for external bosons in any number of spacetime dimensions. Moreover, they generalize to the superamplitudes in theories with 16 supercharges.
Mammalian cycles: internally defined periods and interaction-driven amplitudes
Directory of Open Access Journals (Sweden)
LR Ginzburg
2015-08-01
Full Text Available The cause of mammalian cycles—the rise and fall of populations over a predictable period of time—has remained controversial since these patterns were first observed over a century ago. In spite of extensive work on observable mammalian cycles, the field has remained divided upon what the true cause is, with a majority of opinions attributing it to either predation or to intra-species mechanisms. Here we unite the eigenperiod hypothesis, which describes an internal, maternal effect-based mechanism to explain the cycles’ periods with a recent generalization explaining the amplitude of snowshoe hare cycles in northwestern North America based on initial predator abundance. By explaining the period and the amplitude of the cycle with separate mechanisms, a unified and consistent view of the causation of cycles is reached. Based on our suggested theory, we forecast the next snowshoe hare cycle (predicted peak in 2016 to be of extraordinarily low amplitude.
Measurement of amplitude fluctuations in a rapid response photomultiplier
International Nuclear Information System (INIS)
Raimbault, P.
1961-01-01
In order to measure amplitude fluctuations in a rapid response photomultiplier, two independent random variables are introduced which determine the shape of the anode pulse. The energy of each pulse, which depends directly on the gain and the variance, is the first variable; amplitude fluctuations, functions of the first variable, depend as well on the pulse width which in turn constitutes the second variable. The results obtained on the variations of the maximum impulse, using a steep-edged pulse broadening circuit, and those obtained on the statistical variations of the gain, are compared to show that the variance relative to the maximum amplitude of the signal is greater than that of the gain. Within the limits of these fluctuations are shown the contribution of the secondary emission coefficient of the first dynode, and that of the mean secondary emission coefficient of the multiplier. (author) [fr
Directory of Open Access Journals (Sweden)
Andreas M. Savvides
2018-04-01
Full Text Available The development of technology, like the widely-used off-the-shelf portable photosynthesis systems, for the quantification of leaf gas exchange rates and chlorophyll fluorescence offered photosynthesis research a massive boost. Gas exchange parameters in such photosynthesis systems are calculated as gas exchange rates per unit leaf area. In small chambers (<10 cm2, the leaf area used by the system for these calculations is actually the internal gasket area (AG, provided that the leaf covers the entire AG. In this study, we present two inexpensive and non-destructive techniques that can be used to easily quantify the enclosed leaf area (AL of plant species with leaves of surface area much smaller than the AG, such as that of cereal crops. The AL of the cereal crop species studied has been measured using a standard image-based approach (iAL and estimated using a leaf width-based approach (wAL. iAL and wAL did not show any significant differences between them in maize, barley, hard and soft wheat. Similar results were obtained when the wAL was tested in comparison with iAL in different positions along the leaf in all species studied. The quantification of AL and the subsequent correction of leaf gas exchange parameters for AL provided a precise quantification of net photosynthesis and stomatal conductance especially with decreasing AL. This study provides two practical, inexpensive and non-destructive solutions to researchers dealing with photosynthesis measurements on small-leaf plant species. The image-based technique can be widely used for quantifying AL in many plant species despite their leaf shape. The leaf width-based technique can be securely used for quantifying AL in cereal crop species such as maize, wheat and barley along the leaf. Both techniques can be used for a wide range of gasket shapes and sizes with minor technique-specific adjustments.
Double collinear splitting amplitudes at next-to-leading order
Energy Technology Data Exchange (ETDEWEB)
Sborlini, Germán F.R. [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain); Florian, Daniel de [Departamento de Física and IFIBA, FCEyN, Universidad de Buenos Aires (1428) Pabellón 1 Ciudad Universitaria, Capital Federal (Argentina); Rodrigo, Germán [Instituto de Física Corpuscular, Universitat de València -Consejo Superior de Investigaciones Científicas,Parc Científic, E-46980 Paterna (Valencia) (Spain)
2014-01-07
We compute the next-to-leading order (NLO) QCD corrections to the 1→2 splitting amplitudes in different dimensional regularization (DREG) schemes. Besides recovering previously known results, we explore new DREG schemes and analyze their consistency by comparing the divergent structure with the expected behavior predicted by Catani’s formula. Through the introduction of scalar-gluons, we show the relation among splittings matrices computed using different schemes. Also, we extended this analysis to cover the double collinear limit of scattering amplitudes in the context of QCD+QED.
Numerical construction of 'optimal' nonoscillating amplitude and phase functions
International Nuclear Information System (INIS)
Matzkin, A.; Lombardi, M.
2002-01-01
A numerical recipe for the construction of nonoscillating amplitude and phase functions for potentials with a single minimum is given. We give different examples illustrating the recipe, showing the usefulness of the procedure for the construction of basis functions in bound-state scattering processes, such as those described by quantum defect theory. The resulting amplitude and accumulated phase functions are coined as 'optimal' nonoscillating (as a function of the space and energy variables) because they are the counterpart for the quantum problem of the classical action for the analog semiclassical problem
From magnetized iron bars to amplitude imaging of hadronic reactions
International Nuclear Information System (INIS)
Svec, M.
1989-01-01
Instruments shape research and determine which discoveries are made. Considering spin observables as carriers of information on nonperturbative QCD dynamics in hadronic reactions, we examine the relevance of amplitude analysis for the design goals of high intensity hadron facilities. New instrumental goals emerge: Hadron facility dedicated to continous measurements of spin observables and to cumulative production of computer images of scattering amplitudes over broad kinematic regions. The facility is viewed as a single instrument and termed spinoscope. We stress its connections to frontier developments in computer industries and to studies of nonperturbative states in condensed matter
Asymptotic behaviour of physical amplitudes in a finite field theory
International Nuclear Information System (INIS)
Helayel Neto, J.A.; Rajpoot, S.; Smith, A.W.
1987-01-01
Using the N=4 super-Yang-Mills theory softly broken by supersymmetric N=1 mass terms for matter superfields, we compute the one-loop chiral + chiral → antichiral + antichiral scattering amplitude directly in superspace. By suitable choices of the mass parameters, on can endow the model with a hierarchy of light and heavy particles, and the decoupling of the heavy sector from light-light physical amplitude is studied. We also analyze the high-energy limit of the cross-section for a two physical scalar scattering and find a (logs) behaviour, which then respects the Froissart bound. (author) [pt
Finite Amplitude Electron Plasma Waves in a Cylindrical Waveguide
DEFF Research Database (Denmark)
Juul Rasmussen, Jens
1978-01-01
The nonlinear behaviour of the electron plasma wave propagating in a cylindrical plasma waveguide immersed in an infinite axial magnetic field is investigated using the Krylov-Bogoliubov-Mitropolsky perturbation method, by means of which is deduced the nonlinear Schrodinger equation governing...... the long-time slow modulation of the wave amplitude. From this equation the amplitude-dependent frequency and wavenumber shifts are calculated, and it is found that the electron waves with short wavelengths are modulationally unstable with respect to long-wavelength, low-frequency perturbations...
On tree amplitudes of supersymmetric Einstein-Yang-Mills theory
Energy Technology Data Exchange (ETDEWEB)
Adamo, Tim; Casali, Eduardo; Roehrig, Kai A.; Skinner, David [Department of Applied Mathematics & Theoretical Physics, University of Cambridge,Wilberforce Road, Cambridge, CB3 0WA United Kingdom (United Kingdom)
2015-12-29
We present a new formula for all single trace tree amplitudes in four dimensional super Yang-Mills coupled to Einstein supergravity. Like the Cachazo-He-Yuan formula, our expression is supported on solutions of the scattering equations, but with momenta written in terms of spinor helicity variables. Supersymmetry and parity are both manifest. In the pure gravity and pure Yang-Mills sectors, it reduces to the known twistor-string formulae. We show that the formula behaves correctly under factorization and sketch how these amplitudes may be obtained from a four-dimensional (ambi)twistor string.
RTS amplitudes in decananometer MOSFETs: 3-D simulation study
Asenov, A.; Balasubramaniam, R.; Brown, A.R.; Davies, J.H.
2003-01-01
In this paper we study the amplitudes of random telegraph signals (RTS) associated with the trapping of a single electron in defect states at the Si/SiO/sub 2/ interface of sub-100-nm (decananometer) MOSFETs employing three-dimensional (3-D) "atomistic" simulations. Both continuous doping charge and random discrete dopants in the active region of the MOSFETs are considered in the simulations. The dependence of the RTS amplitudes on the position of the trapped charge in the channel and on devi...
Modulated Source Interferometry with Combined Amplitude and Frequency Modulation
Gutierrez, Roman C. (Inventor)
1998-01-01
An improved interferometer is produced by modifying a conventional interferometer to include amplitude and/or frequency modulation of a coherent light source at radio or higher frequencies. The phase of the modulation signal can be detected in an interfering beam from an interferometer and can be used to determine the actual optical phase of the beam. As such, this improvement can be adapted to virtually any two-beam interferometer, including: Michelson, Mach-Zehnder, and Sagnac interferometers. The use of an amplitude modulated coherent tight source results in an interferometer that combines the wide range advantages of coherent interferometry with the precise distance measurement advantages of white light interferometry.
From maximal to minimal supersymmetry in string loop amplitudes
Energy Technology Data Exchange (ETDEWEB)
Berg, Marcus; Buchberger, Igor [Department of Physics, Karlstad University,651 88 Karlstad (Sweden); Schlotterer, Oliver [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut,14476 Potsdam (Germany)
2017-04-28
We calculate one-loop string amplitudes of open and closed strings with N=1,2,4 supersymmetry in four and six dimensions, by compactification on Calabi-Yau and K3 orbifolds. In particular, we develop a method to combine contributions from all spin structures for arbitrary number of legs at minimal supersymmetry. Each amplitude is cast into a compact form by reorganizing the kinematic building blocks and casting the worldsheet integrals in a basis. Infrared regularization plays an important role to exhibit the expected factorization limits. We comment on implications for the one-loop string effective action.
All-fibre source of amplitude squeezed light pulses
Energy Technology Data Exchange (ETDEWEB)
Meissner, Markus; Marquardt, Christoph; Heersink, Joel; Gaber, Tobias; Wietfeld, Andre; Leuchs, Gerd; Andersen, Ulrik L [Institut fuer Optik, Information und Photonik, Max-Planck Forschungsgruppe Universitaet Erlangen-Nuernberg, Staudtstrasse 7/B2, 91058, Erlangen (Germany)
2004-08-01
An all-fibre source of amplitude squeezed solitons utilizing the self-phase modulation in an asymmetric Sagnac interferometer is experimentally demonstrated. The asymmetry of the interferometer is passively controlled by an integrated fibre coupler, allowing for the optimization of the noise reduction. We have carefully studied the dependence of the amplitude noise on the asymmetry and the power launched into the Sagnac interferometer. Qualitatively, we find good agreement between the experimental results, a semi-classical theory and earlier numerical calculations (Schmitt et al 1998 Phys. Rev. Lett. 81 2446). The stability and flexibility of this all-fibre source makes it particularly well suited to applications in quantum information science.
Enhanced Electroweak Penguin Amplitude in B→VV Decays
International Nuclear Information System (INIS)
Beneke, M.; Rohrer, J.; Yang, D.
2006-01-01
We discuss a novel electromagnetic penguin contribution to the transverse helicity amplitudes in B decays to two vector mesons, which is enhanced by two powers of m B /Λ relative to the standard penguin amplitudes. This leads to unique polarization signatures in penguin-dominated decay modes such as B→ρK* similar to polarization effects in the radiative decay B→K*γ and offers new opportunities to probe the magnitude and chirality of flavor-changing neutral current couplings to photons
Very low luminosity stars with very large amplitude flares
International Nuclear Information System (INIS)
Schaefer, B.E.
1990-01-01
CCD frames of CZ Cnc, KY Cep, the gamma-ray burster optical transient, and NSV 12006 are analyzed. Also studied are 549 archival photographic plates of the CZ Cnc field. These observations are compared with the data of Lovas (1976). Flare events on CZ Cnc are examined. Based on the data it is noted that CZ Cnc is a main-sequence star, has a magnitude of 16.1, a distance of 100 pc, occasional large-amplitude flares, and frequent flares with amplitudes greater than 4 mag. 36 refs
Microscopic theory of dynamical subspace for large amplitude collective motion
International Nuclear Information System (INIS)
Sakata, Fumihiko; Marumori, Toshio; Ogura, Masanori.
1986-01-01
A full quantum theory appropriate for describing large amplitude collective motion is proposed by exploiting the basic idea of the semi-classical theory so far developed within the time-depedent Hartree-Fock theory. A central problem of the quantum theory is how to determine an optimal representation called a dynamical representation specific for the collective subspace where the large amplitude collective motion is replicated as precisely as possible. As an extension of the semi-classical theory where the concept of an approximate integral surface played an important role, the collective subspace is properly characterized by introducing a concept of an approximate invariant subspace of the Hamiltonian. (author)
Photoacoustic microbeam-oscillator with tunable resonance direction and amplitude
Wu, Qingjun; Li, Fanghao; Wang, Bo; Yi, Futing; Jiang, J. Z.; Zhang, Dongxian
2018-01-01
We successfully design one photoacoustic microbeam-oscillator actuated by nanosecond laser, which exhibits tunable resonance direction and amplitude. The mechanism of laser induced oscillation is systematically analyzed. Both simulation and experimental results reveal that the laser induced acoustic wave propagates in a multi-reflected mode, resulting in resonance in the oscillator. This newly-fabricated micrometer-sized beam-oscillator has an excellent actuation function, i.e., by tuning the laser frequency, the direction and amplitude of actuation can be efficiently altered, which will have potential industrial applications.
Improved Modeling and Prediction of Surface Wave Amplitudes
2017-05-31
AFRL-RV-PS- AFRL-RV-PS- TR-2017-0162 TR-2017-0162 IMPROVED MODELING AND PREDICTION OF SURFACE WAVE AMPLITUDES Jeffry L. Stevens, et al. Leidos...data does not license the holder or any other person or corporation; or convey any rights or permission to manufacture, use, or sell any patented...SUBTITLE Improved Modeling and Prediction of Surface Wave Amplitudes 5a. CONTRACT NUMBER FA9453-14-C-0225 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER
International Nuclear Information System (INIS)
Rowland, David R
2013-01-01
Introductory discussions of energy transport due to transverse waves on taut strings universally assume that the effects of longitudinal motion can be neglected, but this assumption is not even approximately valid unless the string is idealized to have a zero relaxed length, a requirement approximately met by the slinky spring. While making this additional idealization is probably the best approach to take when discussing waves on strings at the introductory level, for intermediate to advanced undergraduate classes in continuum mechanics and general wave phenomena where somewhat more realistic models of strings can be investigated, this paper makes the following contributions. First, various approaches to deriving the general energy continuity equation are critiqued and it is argued that the standard continuum mechanics approach to deriving such equations is the best because it leads to a conceptually clear, relatively simple derivation which provides a unique answer of greatest generality. In addition, a straightforward algorithm for calculating the transverse and longitudinal waves generated when a string is driven at one end is presented and used to investigate a cos 2 transverse pulse. This example illustrates much important physics regarding energy transport in strings and allows the ‘attack waves’ observed when strings in musical instruments are struck or plucked to be approximately modelled and analysed algebraically. Regarding the ongoing debate as to whether the potential energy density in a string can be uniquely defined, it is shown by coupling an external energy source to a string that a suggested alternative formula for potential energy density requires an unphysical potential energy to be ascribed to the source for overall energy to be conserved and so cannot be considered to be physically valid. (paper)
Omega-3 fatty acid supplementation and cognitive function: are smaller dosages more beneficial?
Directory of Open Access Journals (Sweden)
Abubakari AR
2014-09-01
Full Text Available Abdul-Razak Abubakari,1 Mohammad-Mahdi Naderali,2 Ebrahim K Naderali3 1School of Health and Life Sciences, Glasgow Caledonian University, London, UK; 2Blue Coat School, Liverpool, UK; 3School of Health Sciences, Liverpool Hope University, Hope Park Campus, Liverpool, UK Abstract: As longevity increases, so does the global prevalence of cognitive dysfunction. Numerous lifestyle and/or dietary interventions such as omega-3 fatty acids have been suggested to improve memory. Therefore, this study examined the consistency and strength of the impact of supplementation of omega-3 fatty acids on overall cognitive function using systematic reviews and meta-analytic methods. Of 905 studies retrieved from all searches, 12 randomized controlled trials were included in the meta-analysis. There were differences between studies reporting outcomes for single memory function parameters. Subgroup analysis of doses used (low versus high indicated that subjects receiving low (<1.73 g/day doses of omega-3 fatty acids had a significant reduction in cognitive decline rate (-0.07, 95% confidence interval -0.01, -0.02 but there was no evidence for beneficial effects at higher doses (+0.04, 95% confidence interval -0.06, +0.14 compared with the placebo group. This study suggests that omega-3 fatty acids may be beneficial in preventing memory decline at lower doses. Keywords: cognitive impairment, Alzheimer's disease, dietary fatty acids, omega-3, docosahexaenoic acid
Distributions of p-values smaller than .05 in psychology: what is going on?
van Aert, Robbie C.M.; Nuijten, Michèle B.; Wicherts, Jelte M.; van Assen, Marcel A.L.M.
2016-01-01
Previous studies provided mixed findings on pecularities in p-value distributions in psychology. This paper examined 258,050 test results across 30,710 articles from eight high impact journals to investigate the existence of a peculiar prevalence of p-values just below .05 (i.e., a bump) in the psychological literature, and a potential increase thereof over time. We indeed found evidence for a bump just below .05 in the distribution of exactly reported p-values in the journals Developmental Psychology, Journal of Applied Psychology, and Journal of Personality and Social Psychology, but the bump did not increase over the years and disappeared when using recalculated p-values. We found clear and direct evidence for the QRP “incorrect rounding of p-value” (John, Loewenstein & Prelec, 2012) in all psychology journals. Finally, we also investigated monotonic excess of p-values, an effect of certain QRPs that has been neglected in previous research, and developed two measures to detect this by modeling the distributions of statistically significant p-values. Using simulations and applying the two measures to the retrieved test results, we argue that, although one of the measures suggests the use of QRPs in psychology, it is difficult to draw general conclusions concerning QRPs based on modeling of p-value distributions. PMID:27077017
Smaller incision size leads to higher predictability in microcoaxial cataract surgery.
Klamann, Matthias K J; Gonnermann, Johannes; Maier, Anna-Karina B; Torun, Necip; Bertelmann, Eckart
2013-01-01
The aim of the study was to compare the clinical outcomes of a 1.8 mm, 2.2 mm, and 2.75 mm microcoaxial cataract surgery system. METHODS. In this retrospective study, 129 eyes of 129 patients were included. Patients underwent phacoemulsification using a Stellaris system or an Infiniti system. The incision size was 1.8 mm, 2.2 mm, or 2.75 mm, respectively. Subjects were examined before surgery and 4 weeks after. The surgically induced astigmatism (SIA) was examined. The SIA in the 1.8 mm group was statistically lower compared to the 2.2 mm group (p=0.046) and the 2.75 mm group (p=0.017). There was no significant difference between the 2.2 mm group and the 2.75 mm group. With the use of appropriate support systems, 1.8 mm incisions appear to result in less SIA than 2.2 mm and 2.75 mm incisions. Advantages may arise from this, especially in the implantation of aspheric, toric, or multifocal lenses.
Directory of Open Access Journals (Sweden)
Kazunori Hirasawa
Full Text Available The aims of this randomized observational case control study were to quantify fixation behavior during standard automated perimetry (SAP with different fixation targets and to evaluate the relationship between fixation behavior and threshold variability at each test point in healthy young participants experienced with perimetry. SAP was performed on the right eyes of 29 participants using the Octopus 900 perimeter, program 32, dynamic strategy. The fixation targets of Point, Cross, and Ring were used for SAP. Fixation behavior was recorded using a wearable eye-tracking glass. All participants underwent SAP twice with each fixation target in a random fashion. Fixation behavior was quantified by calculating the bivariate contour ellipse area (BCEA and the frequency of deviation from the fixation target. The BCEAs (deg2 of Point, Cross, and Ring targets were 1.11, 1.46, and 2.02, respectively. In all cases, BCEA increased significantly with increasing fixation target size (p < 0.05. The logarithmic value of BCEA demonstrated the same tendency (p < 0.05. A positive correlation was identified between fixation behavior and threshold variability for the Point and Cross targets (ρ = 0.413-0.534, p < 0.05. Fixation behavior increased with increasing fixation target size. Moreover, a larger fixation behavior tended to be associated with a higher threshold variability. A small fixation target is recommended during the visual field test.
Marine, Patrick M; Stabin, Michael G; Fernald, Michael J; Brill, Aaron B
2010-05-01
A systematic evaluation has been performed to study how specific absorbed fractions (SAFs) vary with changes in adult body size, for persons of different size but normal body stature. A review of the literature was performed to evaluate how individual organ sizes vary with changes in total body weight of normal-stature individuals. On the basis of this literature review, changes were made to our easily deformable reference adult male and female total-body models. Monte Carlo simulations of radiation transport were performed; SAFs for photons were generated for 10th, 25th, 75th, and 90th percentile adults; and comparisons were made to the reference (50th) percentile SAF values. Differences in SAFs for organs irradiating themselves were between 0.5% and 1.0%/kg difference in body weight, from 15% to 30% overall, for organs within the trunk. Differences in SAFs for organs outside the trunk were not greater than the uncertainties in the data and will not be important enough to change calculated doses. For organs irradiating other organs within the trunk, differences were significant, between 0.3% and 1.1%/kg, or about 8%-33% overall. The differences are interesting and can be used to estimate how different patients' dosimetry might vary from values reported in standard dose tables.
Martinez, Daniel R; Manimala, Neil J; Rafiei, Arash; Hakky, Tariq S; Yang, Chris; Carrion, Rafael
2015-03-01
Aneurysmal dilatation of the corpora cavernosa can occur because of recurrent priapism in the setting of sickle cell disease. We present the first case of a successful implementation of the reduction corporoplasty technique for treatment of a phallus that was "too large for intercourse." We describe the presentation of a 17-year-old male with a history of sickle cell disease with a phallus "too large for intercourse." Patient reported normal erectile function and response with masturbation but also reported inability to penetrate his partner due to the enlarged and disfigured morphology. He had three priapismic episodes since the age of 10 that progressively led to an aneurysmal morphologic deformity of his phallus. Evaluation included a magnetic resonance imaging, which revealed true aneurysmal dilatation of bilateral corpora cavernosa in the middle and distal portions, and diffusely hyperplastic tunica. The main outcome measure is the successful management of phallic disfiguration. Reduction corporoplasty was performed, and the patient reported intact erectile function without aneurysmal recurrence. Patients with significant corporal aneurysmal defects secondary to recurrent priapism can be successfully managed with reduction corporoplasty. © 2014 International Society for Sexual Medicine.
DEFF Research Database (Denmark)
Veje, Christine Wohlfahrt; Andersen, H R; Jensen, Tina Kold
2012-01-01
. The effects were associated with the maternal exposure levels, so that high-exposed boys had smaller genitals than medium-exposed boys, who had smaller genitals than those who were unexposed. Boys of mothers in the high exposure group (n = 23) had 24.7% smaller testes (95% CI: -62.2; -10.1) and 9.4% shorter...... penile length (95% CI: -16.8; -1.1) compared with the unexposed. The testicular volume and penile length at school age could be tracked to measures from the same boys made at 3 months, e.g. those that had small testes at school age also had small testes at 3 months. Pituitary and testicular hormone serum...
Formation region and amplitude of colour superconductivity in an instanton-induced model
Liao Jin Feng
2002-01-01
Colour superconductivity is investigated in the frame of a two flavour instanton-induced model. The ratio of diquark to quark-antiquark coupling constants is restricted to be c/(N sub c -1) with 1 <=c <=2.87 and controls the formation region and amplitude of colour superconductivity. While the finite current quark mass changes the chiral transition significantly, it does not considerably change the colour superconductivity