Code Coupling for Multi-Dimensional Core Transient Analysis

Energy Technology Data Exchange (ETDEWEB)

Park, Jin-Woo; Park, Guen-Tae; Park, Min-Ho; Ryu, Seok-Hee; Um, Kil-Sup; Lee Jae-Il [KEPCO NF, Daejeon (Korea, Republic of)

2015-05-15

After the CEA ejection, the nuclear power of the reactor dramatically increases in an exponential behavior until the Doppler effect becomes important and turns the reactivity balance and power down to lower levels. Although this happens in a very short period of time, only few seconds, the energy generated can be very significant and cause fuel failures. The current safety analysis methodology which is based on overly conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KEPCO Nuclear Fuel(KNF) is developing the multi-dimensional safety analysis methodology to mitigate the consequences of the single CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, sub-channel analysis code THALES, and fuel performance analysis code FROST, which have transient calculation performance, were coupled using message passing interface (MPI). This paper presents the methodology used for code coupling and the preliminary simulation results with the coupled code system (CHASER). Multi-dimensional core transient analysis code system, CHASER, has been developed and it was applied to simulate a single CEA ejection accident. CHASER gave a good prediction of multi-dimensional core transient behaviors during transient. In the near future, the multi-dimension CEA ejection analysis methodology using CHASER is planning to be developed. CHASER is expected to be a useful tool to gain safety margin for reactivity initiated accidents (RIAs), such as a single CEA ejection accident.

Multi-factor authentication

Science.gov (United States)

Hamlet, Jason R; Pierson, Lyndon G

2014-10-21

Detection and deterrence of spoofing of user authentication may be achieved by including a cryptographic fingerprint unit within a hardware device for authenticating a user of the hardware device. The cryptographic fingerprint unit includes an internal physically unclonable function ("PUF") circuit disposed in or on the hardware device, which generates a PUF value. Combining logic is coupled to receive the PUF value, combines the PUF value with one or more other authentication factors to generate a multi-factor authentication value. A key generator is coupled to generate a private key and a public key based on the multi-factor authentication value while a decryptor is coupled to receive an authentication challenge posed to the hardware device and encrypted with the public key and coupled to output a response to the authentication challenge decrypted with the private key.

Multi-Segment Radius Measurement Using an Absolute Distance Meter Through a Null Assembly

Science.gov (United States)

Merle, Cormic; Wick, Eric; Hayden, Joseph

2011-01-01

This system was one of the test methods considered for measuring the radius of curvature of one or more of the 18 segmented mirrors that form the 6.5 m diameter primary mirror (PM) of the James Webb Space Telescope (JWST). The assembled telescope will be tested at cryogenic temperatures in a 17-m diameter by 27-m high vacuum chamber at the Johnson Space Center. This system uses a Leica Absolute Distance Meter (ADM), at a wavelength of 780 nm, combined with beam-steering and beam-shaping optics to make a differential distance measurement between a ring mirror on the reflective null assembly and individual PM segments. The ADM is located inside the same Pressure-Tight Enclosure (PTE) that houses the test interferometer. The PTE maintains the ADM and interferometer at ambient temperature and pressure so that they are not directly exposed to the telescope s harsh cryogenic and vacuum environment. This system takes advantage of the existing achromatic objective and reflective null assembly used by the test interferometer to direct four ADM beamlets to four PM segments through an optical path that is coincident with the interferometer beam. A mask, positioned on a linear slide, contains an array of 1.25 mm diameter circular subapertures that map to each of the 18 PM segments as well as six positions around the ring mirror. A down-collimated 4 mm ADM beam simultaneously covers 4 adjacent PM segment beamlets and one ring mirror beamlet. The radius, or spacing, of all 18 segments can be measured with the addition of two orthogonally-oriented scanning pentaprisms used to steer the ADM beam to any one of six different sub-aperture configurations at the plane of the ring mirror. The interferometer beam, at a wavelength of 687 nm, and the ADM beamlets, at a wavelength of 780 nm, pass through the objective and null so that the rays are normally incident on the parabolic PM surface. After reflecting off the PM, both the ADM and interferometer beams return to their respective

On the null distribution of Bayes factors in linear regression

Science.gov (United States)

We show that under the null, the 2 log (Bayes factor) is asymptotically distributed as a weighted sum of chi-squared random variables with a shifted mean. This claim holds for Bayesian multi-linear regression with a family of conjugate priors, namely, the normal-inverse-gamma prior, the g-prior, and...

Effect of antiferromagnetic interfacial coupling on spin-wave resonance frequency of multi-layer film

Energy Technology Data Exchange (ETDEWEB)

Qiu, Rong-ke, E-mail: rkqiu@163.com; Cai, Wei

2017-08-15

Highlights: • A quantum approach is developed to study the SWR of a bicomponent multi-layer films. • The comparison of the SWR in films with FM and AFM interfacial coupling has been made. • The present results show the method to enhance and adjust the SWR frequency of films. - Abstract: We investigate the spin-wave resonance (SWR) frequency in a bicomponent bilayer and triple-layer films with antiferromagnetic or ferromagnetic interfacial couplings, as function of interfacial coupling, surface anisotropy, interface anisotropy, thickness and external magnetic field, using the linear spin-wave approximation and Green’s function technique. The microwave properties for multi-layer magnetic film with antiferromagnetic interfacial coupling is different from those for multi-layer magnetic film with ferromagnetic interfacial coupling. For the bilayer film with antiferromagnetic interfacial couplings, as the lower (upper) surface anisotropy increases, only the SWR frequencies of the odd (even) number modes increase. The lower (upper) surface anisotropy does not affect the SWR frequencies of the even (odd) number modes{sub .} For the multi-layer film with antiferromagnetic interfacial coupling, the SWR frequency of modes m = 1, 3 and 4 decreases while that of mode m = 2 increases with increasing thickness of the film within a proper parameter region. The present results could be useful in enhancing our fundamental understanding and show the method to enhance and adjust the SWR frequency of bicomponent multi-layer magnetic films with antiferromagnetic or ferromagnetic interfacial coupling.

Coupling between chip based isotachophoresis and multi-collector inductively coupled plasma mass spectrometry for separation and measurement of lanthanides

International Nuclear Information System (INIS)

Vio, Laurent; Cretier, Gerard; Rocca, Jean-Louis; Chartier, Frederic; Geertsen, Valerie; Gourgiotis, Alkiviadis; Isnard, Helene; Morin, Pierre

2012-01-01

This paper presents the conception and fabrication of a micro-system for lanthanides separation and its coupling with a multi-collector inductively coupled plasma mass spectrometer for isotope ratio measurements. The lanthanides separation is based on the isotachophoresis technique and the micro-system conception has been adapted in order to fit with glove box limitations in view of future spent nuclear fuels analysis. The micro-device was tested by using a mixture of standard solutions of natural elements and the separation of 13 lanthanides was successfully performed. The micro-device was then coupled to a multi-collector inductively coupled plasma mass spectrometer for the on-line measurements of Nd and Sm isotope ratios. The isotopes of Nd and Sm were acquired online in multi-collection mode after separation of the two elements with an injection amount of 5 ng. Results obtained on the Nd and Sm isotope ratio measurements on transient signals are presented and discussed. (authors)

RRI-GBT MULTI-BAND RECEIVER: MOTIVATION, DESIGN, AND DEVELOPMENT

International Nuclear Information System (INIS)

Maan, Yogesh; Deshpande, Avinash A.; Chandrashekar, Vinutha; Chennamangalam, Jayanth; Rao, K. B. Raghavendra; Somashekar, R.; Ezhilarasi, M. S.; Sujatha, S.; Kasturi, S.; Sandhya, P.; Duraichelvan, R.; Amiri, Shahram; Aswathappa, H. A.; Sarabagopalan, G.; Ananda, H. M.; Anderson, Gary; Bauserman, Jonah; Beaudet, Carla; Bloss, Marty; Barve, Indrajit V.

2013-01-01

We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive and high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively radio frequency interference free), a common wide-band radio frequency front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Robert C. Byrd Green Bank Telescope using this receiver. The system performance implied by these results and possible improvements are also briefly discussed.

RRI-GBT MULTI-BAND RECEIVER: MOTIVATION, DESIGN, AND DEVELOPMENT

Energy Technology Data Exchange (ETDEWEB)

Maan, Yogesh; Deshpande, Avinash A.; Chandrashekar, Vinutha; Chennamangalam, Jayanth; Rao, K. B. Raghavendra; Somashekar, R.; Ezhilarasi, M. S.; Sujatha, S.; Kasturi, S.; Sandhya, P.; Duraichelvan, R.; Amiri, Shahram; Aswathappa, H. A.; Sarabagopalan, G.; Ananda, H. M. [Raman Research Institute, Bangalore (India); Anderson, Gary; Bauserman, Jonah; Beaudet, Carla; Bloss, Marty [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV (United States); Barve, Indrajit V. [Indian Institute of Astrophysics, Bangalore (India); and others

2013-01-15

We report the design and development of a self-contained multi-band receiver (MBR) system, intended for use with a single large aperture to facilitate sensitive and high time-resolution observations simultaneously in 10 discrete frequency bands sampling a wide spectral span (100-1500 MHz) in a nearly log-periodic fashion. The development of this system was primarily motivated by need for tomographic studies of pulsar polar emission regions. Although the system design is optimized for the primary goal, it is also suited for several other interesting astronomical investigations. The system consists of a dual-polarization multi-band feed (with discrete responses corresponding to the 10 bands pre-selected as relatively radio frequency interference free), a common wide-band radio frequency front-end, and independent back-end receiver chains for the 10 individual sub-bands. The raw voltage time sequences corresponding to 16 MHz bandwidth each for the two linear polarization channels and the 10 bands are recorded at the Nyquist rate simultaneously. We present the preliminary results from the tests and pulsar observations carried out with the Robert C. Byrd Green Bank Telescope using this receiver. The system performance implied by these results and possible improvements are also briefly discussed.

Phenomenological model for coupled multi-axial piezoelectricity

Science.gov (United States)

Wei, Yuchen; Pellegrino, Sergio

2018-03-01

A quantitative calibration of an existing phenomenological model for polycrystalline ferroelectric ceramics is presented. The model relies on remnant strain and polarization as independent variables. Innovative experimental and numerical model identification procedures are developed for the characterization of the coupled electro-mechanical, multi-axial nonlinear constitutive law. Experiments were conducted on thin PZT-5A4E plates subjected to cross-thickness electric field. Unimorph structures with different thickness ratios between PZT-5A4E plate and substrate were tested, to subject the piezo plates to coupled electro-mechanical fields. Material state histories in electric field-strain-polarization space and stress-strain-polarization space were recorded. An optimization procedure is employed for the determination of the model parameters, and the calibrated constitutive law predicts both the uncoupled and coupled experimental observations accurately.

'To give is better than to receive?' Couples massage significantly benefits both partners' wellbeing.

Science.gov (United States)

Naruse, Sayuri M; Cornelissen, Piers L; Moss, Mark

2018-03-01

This experimental study evaluated the differential effects of 'giving' and 'receiving' massage on wellbeing in healthy but stressed couples. Forty-two volunteers started the study and of these, 38 (i.e. 19 couples) completed a 3-week massage course. Emotional stress and mental clarity were assessed before and after mutual massage between each pair of adults belonging to a couple at home. While massage benefitted both parties' wellbeing within a session, critically we found no differences in wellbeing between those 'giving' and 'receiving' massage. These novel findings suggest that home-based massage may be advocated to couples as a 'selves-care', health-promoting behaviour.

Effect of inter-tissue inductive coupling on multi-frequency imaging of intracranial hemorrhage by magnetic induction tomography

Science.gov (United States)

Xiao, Zhili; Tan, Chao; Dong, Feng

2017-08-01

Magnetic induction tomography (MIT) is a promising technique for continuous monitoring of intracranial hemorrhage due to its contactless nature, low cost and capacity to penetrate the high-resistivity skull. The inter-tissue inductive coupling increases with frequency, which may lead to errors in multi-frequency imaging at high frequency. The effect of inter-tissue inductive coupling was investigated to improve the multi-frequency imaging of hemorrhage. An analytical model of inter-tissue inductive coupling based on the equivalent circuit was established. A set of new multi-frequency decomposition equations separating the phase shift of hemorrhage from other brain tissues was derived by employing the coupling information to improve the multi-frequency imaging of intracranial hemorrhage. The decomposition error and imaging error are both decreased after considering the inter-tissue inductive coupling information. The study reveals that the introduction of inter-tissue inductive coupling can reduce the errors of multi-frequency imaging, promoting the development of intracranial hemorrhage monitoring by multi-frequency MIT.

Mitigation Technique for Receiver Performance Variation of Multi-Color Channels in Visible Light Communication

Directory of Open Access Journals (Sweden)

Yeong Min Jang

2011-06-01

Full Text Available “Green” and energy-efficient wireless communication schemes have recently experienced rapid development and garnered much interest. One such scheme is visible light communication (VLC which is being touted as one of the next generation wireless communication systems. VLC allows communication using multi-color channels that provide high data rates and illumination simultaneously. Even though VLC has many advantageous features compared with RF technologies, including visibility, ubiquitousness, high speed, high security, harmlessness for the human body and freedom of RF interference, it suffers from some problems on the receiver side, one of them being photo sensitivity dissimilarity of the receiver. The photo sensitivity characteristics of a VLC receiver such as Si photo-detector depend on the wavelength variation. The performance of the VLC receiver is not uniform towards all channel colors, but it is desirable for receivers to have the same performance on each color channel. In this paper, we propose a mitigation technique for reducing the performance variation of the receiver on multi-color channels. We show received power, SNR, BER, output current, and outage probability in our simulation for different color channels. Simulation results show that, the proposed scheme can reduce the performance variation of the VLC receiver on multi-color channels.

PERSEE: a nulling interferometer with dynamic correction of external perturbations

Science.gov (United States)

Jacquinod, S.; Houairi, K.; Le Duigou, J.-M.; Barillot, M.; Cassaing, F.; Réess, J.-M.; Hénault, F.; Sorrente, B.; Morinaud, G.; Amans, J.-P.; Coudé du Foresto, V.; Ollivier, M.

2017-11-01

Nulling interferometry is one of the direct detection methods assessed to find and characterize extrasolar planets and particularly telluric ones. Several projects such as Darwin [1;2], TPF-I [3;4], PEGASE [5;6] or FKSI [7], are currently considered. One of the main issues is the feasibility of a stable polychromatic null despite the presence of significant disturbances, induced by vibrations, atmospheric turbulence on the ground or satellite drift. Satisfying all these requirements is a great challenge and a key issue of these missions. In the context of the PEGASE mission, it was decided (in 2006), to build a laboratory demonstrator named PERSEE. It is the first laboratory setup which couples deep nulling interferometry with a free flying GNC simulator [8]. It is developed by a consortium composed of CNES, IAS, LESIA, OCA, ONERA, and TAS. In this paper, we detail the main objectives, the set-up and the function of the bench. We describe all the subsystems and we focus particularly on two key points of PERSEE: the beam combiner and the Fringe tracker.

Null half-supersymmetric solutions in five-dimensional supergravity

International Nuclear Information System (INIS)

Grover, Jai; Gutowski, Jan B.; Sabra, Wafic

2008-01-01

We classify half-supersymmetric solutions of gauged N = 2, D = 5 supergravity coupled to an arbitrary number of abelian vector multiplets for which all of the Killing spinors generate null Killing vectors. We show that there are four classes of solutions, and in each class we find the metric, scalars and gauge field strengths. When the scalar manifold is symmetric, the solutions correspond to a class of local near horizon geometries recently found by Kunduri and Lucietti.

Averaged null energy condition from causality

Science.gov (United States)

Hartman, Thomas; Kundu, Sandipan; Tajdini, Amirhossein

2017-07-01

Unitary, Lorentz-invariant quantum field theories in flat spacetime obey mi-crocausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, ∫ duT uu , must be non-negative. This non-local operator appears in the operator product expansion of local operators in the lightcone limit, and therefore contributes to n-point functions. We derive a sum rule that isolates this contribution and is manifestly positive. The argument also applies to certain higher spin operators other than the stress tensor, generating an infinite family of new constraints of the form ∫ duX uuu··· u ≥ 0. These lead to new inequalities for the coupling constants of spinning operators in conformal field theory, which include as special cases (but are generally stronger than) the existing constraints from the lightcone bootstrap, deep inelastic scattering, conformal collider methods, and relative entropy. We also comment on the relation to the recent derivation of the averaged null energy condition from relative entropy, and suggest a more general connection between causality and information-theoretic inequalities in QFT.

Red hair is the null phenotype of MC1R.

Science.gov (United States)

Beaumont, Kimberley A; Shekar, Sri N; Cook, Anthony L; Duffy, David L; Sturm, Richard A

2008-08-01

The Melanocortin-1 Receptor (MC1R) is a G-protein coupled receptor, which is responsible for production of the darker eumelanin pigment and the tanning response. The MC1R gene has many polymorphisms, some of which have been linked to variation in pigmentation phenotypes within human populations. In particular, the p.D84E, p.R151C, p.R160W and p.D294 H alleles have been strongly associated with red hair, fair skin and increased skin cancer risk. These red hair colour (RHC) variants are relatively well described and are thought to result in altered receptor function, while still retaining varying levels of signaling ability in vitro. The mouse Mc1r null phenotype is yellow fur colour, the p.R151C, p.R160W and p.D294 H alleles were able to partially rescue this phenotype, leading to the question of what the true null phenotype of MC1R would be in humans. Due to the rarity of MC1R null alleles in human populations, they have only been found in the heterozygous state until now. We report here the first case of a homozygous MC1R null individual, phenotypic analysis indicates that red hair and fair skin is found in the absence of MC1R function.

A formation control strategy with coupling weights for the multi-robot system

Science.gov (United States)

Liang, Xudong; Wang, Siming; Li, Weijie

2017-12-01

The distributed formation problem of the multi-robot system with general linear dynamic characteristics and directed communication topology is discussed. In order to avoid that the multi-robot system can not maintain the desired formation in the complex communication environment, the distributed cooperative algorithm with coupling weights based on zipf distribution is designed. The asymptotic stability condition for the formation of the multi-robot system is given, and the theory of the graph and the Lyapunov theory are used to prove that the formation can converge to the desired geometry formation and the desired motion rules of the virtual leader under this condition. Nontrivial simulations are performed to validate the effectiveness of the distributed cooperative algorithm with coupling weights.

Multi-Synchronization Caused by Uniform Disorder for Globally Coupled Maps

International Nuclear Information System (INIS)

Jing-Hui, Li

2008-01-01

We investigate the motion of the globally coupled maps (logistic map) driven by uniform disorder. It is shown that this disorder can produce multi-synchronization for the globally coupled chaotic maps studied by us. The disorder determines the synchronized dynamics, leading to the emergence of a wide range of new collective behaviour in which the individual units in isolation are incapable of producing in the absence of the disorder. Our results imply that the disorder can tame the collective motion of the coupled chaotic maps

A Receiver-Initiated Collision-Avoidance Protocol for Multi-Channel Networks

Science.gov (United States)

2001-01-01

00-00-2001 to 00-00-2001 4. TITLE AND SUBTITLE A Receiver-Initiated Collision-Avoidance Protocol for Multi-Channel Netowrks 5a. CONTRACT NUMBER...images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 10 19a. NAME OF RESPONSIBLE

A quasiparticle-based multi-reference coupled-cluster method.

Science.gov (United States)

Rolik, Zoltán; Kállay, Mihály

2014-10-07

The purpose of this paper is to introduce a quasiparticle-based multi-reference coupled-cluster (MRCC) approach. The quasiparticles are introduced via a unitary transformation which allows us to represent a complete active space reference function and other elements of an orthonormal multi-reference (MR) basis in a determinant-like form. The quasiparticle creation and annihilation operators satisfy the fermion anti-commutation relations. On the basis of these quasiparticles, a generalization of the normal-ordered operator products for the MR case can be introduced as an alternative to the approach of Mukherjee and Kutzelnigg [Recent Prog. Many-Body Theor. 4, 127 (1995); Mukherjee and Kutzelnigg, J. Chem. Phys. 107, 432 (1997)]. Based on the new normal ordering any quasiparticle-based theory can be formulated using the well-known diagram techniques. Beyond the general quasiparticle framework we also present a possible realization of the unitary transformation. The suggested transformation has an exponential form where the parameters, holding exclusively active indices, are defined in a form similar to the wave operator of the unitary coupled-cluster approach. The definition of our quasiparticle-based MRCC approach strictly follows the form of the single-reference coupled-cluster method and retains several of its beneficial properties. Test results for small systems are presented using a pilot implementation of the new approach and compared to those obtained by other MR methods.

Lower hybrid wave coupling in Tore Supra through multi junction launchers

International Nuclear Information System (INIS)

Litaudon, X.; Berger By, G.; Bibet, P.; Bizarro, J.P.; Capitain, J.J.; Carrasco, J.; Goniche, M.; Hoang, G.T.; Kupfer, K.; Magne, R.; Moreau, D.; Peysson, Y.; Rax, J.M.; Rey, G.; Rigaud, D.; Tonon, G.

1992-01-01

The TORE SUPRA Lower Hybrid Current Drive experiments (8 MW/3.7GHz) use large phased waveguide arrays, to couple the waves to the plasma. These launchers are based on the multi junction principle. Extensive coupling measurements have been performed in order to study the Radio-Frequency (RF) characteristics of the plasma loaded antennae and are reported. Measurements of the plasma scattering coefficients of the antennae show good agreement with those obtained from the linear coupling theory (SWAN code). Global reflection coefficients of a few percents have been measured in a large range of edge plasma densities or antenna positions, and up to a maximum injected RF power density of 45MW/m 2 . When the plasma is pushed against the inner wall of the chamber, the reflection coefficient was found to remain low up to distances of the order of 10 cm. The coupling measurements allow us to deduce the experimental power spectra radiated by the antennae when all their modules are fed simultaneously with variable phases. An assessment of the multi junction launcher as a viable antenna for high power transmission with good coupling characteristics and spectrum control is thus made

Air-Coupled Ultrasonic Receivers with High Electromechanical Coupling PMN-32%PT Strip-Like Piezoelectric Elements

Directory of Open Access Journals (Sweden)

Rymantas J. Kazys

2017-10-01

Full Text Available For improvement of the efficiency of air-coupled ultrasonic transducers PMN-32%PT piezoelectric crystals which possess very high piezoelectric properties may be used. The electromechanical coupling factor of such crystals for all main vibration modes such as the thickness extension and transverse extension modes is more than 0.9. Operation of ultrasonic transducers with such piezoelectric elements in transmitting and receiving modes is rather different. Therefore, for transmission and reception of ultrasonic signals, separate piezoelectric elements with different dimensions must be used. The objective of this research was development of novel air-coupled ultrasonic receivers with PMN-32%PT strip-like piezoelectric elements vibrating in a transverse-extension mode with electromechanically controlled operation and suitable for applications in ultrasonic arrays. Performance of piezoelectric receivers made of the PMN-32%PT strip-like elements vibrating in this mode may be efficiently controlled by selecting geometry of the electrodes covering side surfaces of the piezoelectric element. It is equivalent to introduction of electromechanical damping which does not require any additional backing element. For this purpose; we have proposed the continuous electrodes to divide into two pairs of electrodes. The one pair is used to pick up the electric signal; another one is exploited for electromechanical damping. Two types of electrodes may be used—rectangular or non-rectangular—with a gap between them directed at some angle, usually 45°. The frequency bandwidth is wider (up to 9 kHz in the case of non-rectangular electrodes. The strip-like acoustic matching element bonded to the tip of the PMN-32%PT crystal may significantly enhance the performance of the ultrasonic receiver. It was proposed to use for this purpose AIREX T10.110 rigid polymer foam, the acoustic impedance of which is close to the optimal value necessary for matching with air. It was

A NEXT GENERATION MULTI-BEAM FOCAL PLANE ARRAY RECEIVER OF TRAO FOR 86-115 GHZ BAND

Directory of Open Access Journals (Sweden)

Moon-Hee Chung

2006-03-01

Full Text Available The noise temperature of existing millimeter-wave receivers is already within two or three times quantum noise limit. One of practical ways to increase the observation speed of single dish radio telescope without longer integration time is use of multi-beam focal plane array receiver as demonstrated in several large single dish radio telescopes. In this context the TRAO (Taeduk Radio Astronomy Observatory, which operates a 143n Cassegrain radio telescope, is planning to develop a 4 x 4 beams focal plane array SIS receiver system for 86-115 GHz band. Even though millimeter-wave HEMT LNA-based receivers approach the noise temperature comparable to the SIS receiver at W-band, it is believed that the receiver based on SIS mixer seems to offer a bit more advantages. The critical part of the multi-beam array receiver will be sideband separating SIS mixers. Employing such a type of SIS mixer makes it possible to simplify the quasi-optics of receiver. Otherwise, an SSB filter should be used in front of the mixer or some sophisticated post-processing of observation data is needed. In this paper we will present a preliminary design concept and components needed for the development of a new 3 mm band multi-beam focal plane array receiver.

Stochastic resonance in multi-stable coupled systems driven by two driving signals

Science.gov (United States)

Xu, Pengfei; Jin, Yanfei

2018-02-01

The stochastic resonance (SR) in multi-stable coupled systems subjected to Gaussian white noises and two different driving signals is investigated in this paper. Using the adiabatic approximation and the perturbation method, the coupled systems with four-well potential are transformed into the master equations and the amplitude of the response is obtained. The signal-to-noise ratio (SNR) is calculated numerically to demonstrate the occurrence of SR. For the case of two driving signals with different amplitudes, the interwell resonance between two wells S1 and S3 emerges for strong coupling. The SR can appear in the subsystem with weaker signal amplitude or even without driving signal with the help of coupling. For the case of two driving signals with different frequencies, the effects of SR in two subsystems driven by high and low frequency signals are both weakened with an increase in coupling strength. The stochastic multi-resonance phenomenon is observed in the subsystem subjected to the low frequency signal. Moreover, an effective scheme for phase suppressing SR is proposed by using a relative phase between two driving signals.

Multi-Destination Cognitive Radio Relay Network with SWIPT and Multiple Primary Receivers

KAUST Repository

Al-Habob, Ahmed A.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

2017-01-01

In this paper, we study the performance of simultaneous wireless information and power transfer (SWIPT) technique in a multi-destination dual-hop underlay cognitive relay network with multiple primary receivers. Information transmission from

On smoothness-asymmetric null infinities

International Nuclear Information System (INIS)

Valiente Kroon, Juan Antonio

2006-01-01

We discuss the existence of asymptotically Euclidean initial data sets for the vacuum Einstein field equations which would give rise (modulo an existence result for the evolution equations near spatial infinity) to developments with a past and a future null infinity of different smoothness. For simplicity, the analysis is restricted to the class of conformally flat, axially symmetric initial data sets. It is shown how the free parameters in the second fundamental form of the data can be used to satisfy certain obstructions to the smoothness of null infinity. The resulting initial data sets could be interpreted as those of some sort of (nonlinearly) distorted Schwarzschild black hole. Their developments would be that they admit a peeling future null infinity, but at the same time have a polyhomogeneous (non-peeling) past null infinity

Null solution of the Yang-Mills equations

International Nuclear Information System (INIS)

Tafel, J.

1986-05-01

We investigate the correspondence between null solutions of the Yang-Mills equations and shearfree geodesic null congruences. We give an example of a non-Abelian null solution with twisting rays. (orig.)

Hierarchies of multi-component mKP equations and theirs integrable couplings

International Nuclear Information System (INIS)

Ji Jie; Yao Yuqin; Zhu Fubo; Chen Dengyuan

2008-01-01

First, a new multi-component modified Kadomtsev-Petviashvill (mKP) spectral problem is constructed by k-constraint imposed on a general pseudo-differential operator. Then, two hierarchies of multi-component mKP equations are derived, including positive non-isospectral mKP hierarchy and negative non-isospectral mKP hierarchy. Moreover, new integrable couplings of the resulting mKP soliton hierarchies are constructed by enlarging the associated matrix spectral problem

Harmonic Coupling Analysis of a Multi-Drive System with Slim DC-link Drive

DEFF Research Database (Denmark)

Yang, Feng; Kwon, Jun Bum; Blaabjerg, Frede

2017-01-01

One of the problems with slim dc-link adjustable speed drive is the difficulties to analyze the harmonic coupling when it is integrated into a multi-drive system. The traditional methods analyze this harmonic issue by neglecting the harmonic coupling, and base on the linear time-invariant methods....... Its disadvantages include the time consumption and large computer memory. This paper proposes to do harmonic analysis by using the harmonic state-space modeling method by using the linear time-periodic theory. By using the proposed model, the harmonic couplings, between dc-link and point of common...... coupling in different drives, are all analyzed in the multi-drive system. In the meantime, the effects of the small film dc-link capacitance and the nonlinear characteristic of the diode rectifier are considered. The detailed modeling procedure, the simulations and the lab experiment on a two-drive system...

Null-strut calculus. II. Dynamics

International Nuclear Information System (INIS)

Kheyfets, A.; LaFave, N.J.; Miller, W.A.

1990-01-01

In this paper, we continue from the preceding paper to develop a fully functional Regge calculus geometrodynamic algorithm from the null-strut-calculus construction. The developments discussed include (a) the identification of the Regge calculus analogue of the constraint and evolution equations on the null-strut lattice, (b) a description of the Minkowski solid geometry for the simplicial blocks of the null-strut lattice, (c) a description of the evolution algorithm for the geometrodynamic scheme and an analysis of its consistency, and (d) a presentation of the dynamical degrees of freedom for a simplicial hypersurface and the description of an initial-value prescription. To demonstrate qualitatively this new approach to geometrodynamics, we present the most simple application of null-strut calculus that we know of---the Friedmann cosmology using the three-boundary of a 600-cell simplicial polytope to model the simplicial hypersurface

Visible Nulling Coronagraph Progress Report

Science.gov (United States)

Lyon, R. G.; Clampin, M.; Woodruff, R. A.; Vasudevan, G.; Thompson, P.; Petrone, P.; Madison, T.; Rizzo, M.; Melnick, G.; Tolls, V.

2010-10-01

We report on recent laboratory results with the NASA Goddard Space Flight Center Visible Nulling Coronagraph (VNC) testbed. We have achieved focal plane contrasts of 108 and approaching 109 at inner working angles of 2 λ/D and 4 λ/D, respectively. Results were obtained with a broadband source and 40 nm filter centered on 630 nm. A null control breadboard (NCB) was also developed to assess and quantify MEMS based deformable mirror technology (DM), and to develop and assess closed-loop null control algorithms. We have demonstrated closed-loop performance at 27 Hz.

Multi-wing hyperchaotic attractors from coupled Lorenz systems

International Nuclear Information System (INIS)

Grassi, Giuseppe; Severance, Frank L.; Miller, Damon A.

2009-01-01

This paper illustrates an approach to generate multi-wing attractors in coupled Lorenz systems. In particular, novel four-wing (eight-wing) hyperchaotic attractors are generated by coupling two (three) identical Lorenz systems. The paper shows that the equilibria of the proposed systems have certain symmetries with respect to specific coordinate planes and the eigenvalues of the associated Jacobian matrices exhibit the property of similarity. In analogy with the original Lorenz system, where the two-wings of the butterfly attractor are located around the two equilibria with the unstable pair of complex-conjugate eigenvalues, this paper shows that the four-wings (eight-wings) of these attractors are located around the four (eight) equilibria with two (three) pairs of unstable complex-conjugate eigenvalues.

Visible nulling coronagraph testbed results

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Thompson, Patrick; Petrone, Peter; Madison, Timothy; Rizzo, Maxime; Melnick, Gary; Tolls, Volker

2009-08-01

We report on our recent laboratory results with the NASA/Goddard Space Flight Center (GSFC) Visible Nulling Coronagraph (VNC) testbed. We have experimentally achieved focal plane contrasts of 1 x 108 and approaching 109 at inner working angles of 2 * wavelength/D and 4 * wavelength/D respectively where D is the aperture diameter. The result was obtained using a broadband source with a narrowband spectral filter of width 10 nm centered on 630 nm. To date this is the deepest nulling result with a visible nulling coronagraph yet obtained. Developed also is a Null Control Breadboard (NCB) to assess and quantify MEMS based segmented deformable mirror technology and develop and assess closed-loop null sensing and control algorithm performance from both the pupil and focal planes. We have demonstrated closed-loop control at 27 Hz in the laboratory environment. Efforts are underway to first bring the contrast to > 109 necessary for the direct detection and characterization of jovian (Jupiter-like) and then to > 1010 necessary for terrestrial (Earth-like) exosolar planets. Short term advancements are expected to both broaden the spectral passband from 10 nm to 100 nm and to increase both the long-term stability to > 2 hours and the extent of the null out to a ~ 10 * wavelength / D via the use of MEMS based segmented deformable mirror technology, a coherent fiber bundle, achromatic phase shifters, all in a vacuum chamber at the GSFC VNC facility. Additionally an extreme stability textbook sized compact VNC is under development.

The quantum null energy condition in curved space

Science.gov (United States)

Fu, Zicao; Koeller, Jason; Marolf, Donald

2017-11-01

The quantum null energy condition (QNEC) is a conjectured bound on components (Tkk = Tab ka k^b) of the stress tensor along a null vector k a at a point p in terms of a second k-derivative of the von Neumann entropy S on one side of a null congruence N through p generated by k a . The conjecture has been established for super-renormalizeable field theories at points p that lie on a bifurcate Killing horizon with null tangent k a and for large-N holographic theories on flat space. While the Koeller-Leichenauer holographic argument clearly yields an inequality for general ( p, k^a) , more conditions are generally required for this inequality to be a useful QNEC. For d≤slant 3 , for arbitrary backgroud metric we show that the QNEC is naturally finite and independent of renormalization scheme when the expansion θ of N at the point p vanishes. This is consistent with the original QNEC conjecture which required θ and the shear σab to satisfy θ \\vert _p= \\dotθ\\vert p =0 , σab\\vert _p=0 . But for d=4, 5 more conditions than even these are required. In particular, we also require the vanishing of additional derivatives and a dominant energy condition. In the above cases the holographic argument does indeed yield a finite QNEC, though for d≥slant6 we argue these properties to fail even for weakly isolated horizons (where all derivatives of θ, σab vanish) that also satisfy a dominant energy condition. On the positive side, a corrollary to our work is that, when coupled to Einstein-Hilbert gravity, d ≤slant 3 holographic theories at large N satisfy the generalized second law (GSL) of thermodynamics at leading order in Newton’s constant G. This is the first GSL proof which does not require the quantum fields to be perturbations to a Killing horizon.

Internal multi-scale multi-physics coupled system for high fidelity simulation of light water reactors

International Nuclear Information System (INIS)

Ivanov, A.; Sanchez, V.; Stieglitz, R.; Ivanov, K.

2014-01-01

Highlights: • The current paper focuses on a optimized method for performing coupled Monte-Carlo/thermal–hydraulics calculations. • Innovative on-the-fly method for supplying the temperature and density distributions is presented. • Convergence acceleration method is presented. It is proven applicable by generalizing the Robbins-Monro theorem. • Tallying is optimized by using collision probability estimator for the power profile estimation. - Abstract: In order to increase the accuracy and the degree of spatial and energy resolution of core design studies, coupled 3D neutronic (multi-group deterministic and continuous energy Monte-Carlo) and 3D thermal–hydraulic (CFD and subchannel) codes are being developed worldwide. At KIT, both deterministic and Monte-Carlo codes were coupled with subchannel codes and applied to predict the safety-related design parameters such as minimal critical power ratio (MCPR), maximal cladding and fuel temperature, departure from nuclide boiling ratio (DNBR). These coupling approaches were revised and considerably improved. Innovative method of internal on-the-fly thermal feedback interchange between the codes was implemented. It no longer relies on explicit material definitions and allows the modeling of temperature and density distributions based on the cell coordinates. In contrast to all existing coupled schemes, this method uses only standard MCNP geometry input and requires only proper definition of the geometrical dimensions. The initial material definition is arbitrary and is determined on-the-fly during the neutron transport by the thermal–hydraulic feedback. Another key issue addressed is the optimal application of parallel computing and the implementation of less time consuming tally estimators. Using multi-processor computer architectures and implementing collision density flux estimator, it is possible to reduce the Monte-Carlo running time and obtain converged results within reasonable time limit. The coupled

Telescopes in Near Space: Balloon Exoplanet Nulling Interferometer (BigBENI)

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Mauk, Robin

2012-01-01

A significant and often overlooked path to advancing both science and technology for direct imaging and spectroscopic characterization of exosolar planets is to fly "near space" missions, i.e. balloon borne exosolar missions. A near space balloon mission with two or more telescopes, coherently combined, is capable of achieving a subset of the mission science goals of a single large space telescope at a small fraction of the cost. Additionally such an approach advances technologies toward flight readiness for space flight. Herein we discuss the feasibility of flying two 1.2 meter telescopes, with a baseline separation of 3.6 meters, operating in visible light, on a composite boom structure coupled to a modified visible nulling coronagraph operating to achieve an inner working angle of 60 milli-arcseconds. We discuss the potential science return, atmospheric residuals at 135,000 feet, pointing control and visible nulling and evaluate the state-or-art of these technologies with regards to balloon missions.

Null structure groups in eleven dimensions

International Nuclear Information System (INIS)

Cariglia, Marco; Mac Conamhna, Oisin A. P.

2006-01-01

We classify all the structure groups which arise as subgroups of the isotropy group (Spin(7)xR 8 )xR, of a single null Killing spinor in 11 dimensions. We construct the spaces of spinors fixed by these groups. We determine the conditions under which structure subgroups of the maximal null structure group (Spin(7)xR 8 )xR may also be embedded in SU(5), and hence the conditions under which a supersymmetric spacetime admits only null, or both timelike and null, Killing spinors. We discuss how this purely algebraic material will facilitate the direct analysis of the Killing spinor equation of 11 dimensional supergravity, and the classification of supersymmetric spacetimes therein

Geometrical exploration of a flux-optimised sodium receiver through multi-objective optimisation

Science.gov (United States)

Asselineau, Charles-Alexis; Corsi, Clothilde; Coventry, Joe; Pye, John

2017-06-01

A stochastic multi-objective optimisation method is used to determine receiver geometries with maximum second law efficiency, minimal average temperature and minimal surface area. The method is able to identify a set of Pareto optimal candidates that show advantageous geometrical features, mainly in being able to maximise the intercepted flux within the geometrical boundaries set. Receivers with first law thermal efficiencies ranging from 87% to 91% are also evaluated using the second law of thermodynamics and found to have similar efficiencies of over 60%, highlighting the influence that the geometry can play in the maximisation of the work output of receivers by influencing the distribution of the flux from the concentrator.

Multi-DSP and FPGA based Multi-channel Direct IF/RF Digital receiver for atmospheric radar

Science.gov (United States)

Yasodha, Polisetti; Jayaraman, Achuthan; Kamaraj, Pandian; Durga rao, Meka; Thriveni, A.

2016-07-01

Modern phased array radars depend highly on digital signal processing (DSP) to extract the echo signal information and to accomplish reliability along with programmability and flexibility. The advent of ASIC technology has made various digital signal processing steps to be realized in one DSP chip, which can be programmed as per the application and can handle high data rates, to be used in the radar receiver to process the received signal. Further, recent days field programmable gate array (FPGA) chips, which can be re-programmed, also present an opportunity to utilize them to process the radar signal. A multi-channel direct IF/RF digital receiver (MCDRx) is developed at NARL, taking the advantage of high speed ADCs and high performance DSP chips/FPGAs, to be used for atmospheric radars working in HF/VHF bands. Multiple channels facilitate the radar t be operated in multi-receiver modes and also to obtain the wind vector with improved time resolution, without switching the antenna beam. MCDRx has six channels, implemented on a custom built digital board, which is realized using six numbers of ADCs for simultaneous processing of the six input signals, Xilinx vertex5 FPGA and Spartan6 FPGA, and two ADSPTS201 DSP chips, each of which performs one phase of processing. MCDRx unit interfaces with the data storage/display computer via two gigabit ethernet (GbE) links. One of the six channels is used for Doppler beam swinging (DBS) mode and the other five channels are used for multi-receiver mode operations, dedicatedly. Each channel has (i) ADC block, to digitize RF/IF signal, (ii) DDC block for digital down conversion of the digitized signal, (iii) decoding block to decode the phase coded signal, and (iv) coherent integration block for integrating the data preserving phase intact. ADC block consists of Analog devices make AD9467 16-bit ADCs, to digitize the input signal at 80 MSPS. The output of ADC is centered around (80 MHz - input frequency). The digitized data is fed

Multi-Destination Cognitive Radio Relay Network with SWIPT and Multiple Primary Receivers

KAUST Repository

Al-Habob, Ahmed A.

2017-05-12

In this paper, we study the performance of simultaneous wireless information and power transfer (SWIPT) technique in a multi-destination dual-hop underlay cognitive relay network with multiple primary receivers. Information transmission from the secondary source to destinations is performed entirely via a decode- and-forward (DF) relay. The relay is assumed to have no embedded power source and to harvest energy from the source signal using a power splitting (PS) protocol and employing opportunistic scheduling to forward the information to the selected destination. We derive analytical expressions for the outage probability assuming Rayleigh fading channels and considering the energy harvesting efficiency at relay, the source maximum transmit power and primary receivers interference constraints. The system performance is also studied at high signal-to-noise ratio (SNR) values where approximate expressions for the outage probability are provided and analyzed in terms of diversity order and coding gain. Monte-Carlo simulations and some numerical examples are provided to validate the derived expressions and to illustrate the effect of various system parameters on the system performance. In contrast to their conventional counterparts where a multi- destination diversity is usually achieved, the results show that the multi-destination cognitive radio relay networks with the SWIPT technique achieve a constant diversity order of one.

Theory and experiment of laterally coupled multi-longitudinal-mode semiconductor lasers

NARCIS (Netherlands)

Lenstra, D.; Yousefi, M.; Barsella, A.; Morthier, G.; Baets, R.G.F.; McMurtry, S.; Vilcot, J.-P.

2003-01-01

This report presents simulations and measurements of multimode dynamics in the twin-stripe laser resulting from complicated gain competition effects. The theory is based on a novel multi-longitudinal rate equations model, while accounting for both coherent and incoherent lateral coupling between the

A 0.8–8 GHz Multi-Section Coupled Line Balun

Directory of Open Access Journals (Sweden)

Srikanth Itapu

2015-04-01

Full Text Available In this work, we propose a wideband multi-section transforming coupled-line balun using near equal length transmission line elements. The resulting design is realized by cascading several coupled-lines with minimal discontinuities. The multi-section Chebyshev matching optimizes bandwidth at the expense of passband ripple. The proposed design delivers good impedance matching and consistent 180° phase shift over 0.8–8 GHz frequency spectrum. Furthermore, the need for vias in conventional balun designs is relaxed by replacing the short-circuited (SC terminal by its equivalent dual open-circuited (OC element. The proposed design is simulated, fabricated, and measured. Both simulated and measured results are in a good agreement, and show an input port matching of below −9.7 dB over the design bandwidth, with a maximum phase and amplitude imbalance of 2.1° and 0.9 dB, respectively.

On the Penrose inequality along null hypersurfaces

International Nuclear Information System (INIS)

Mars, Marc; Soria, Alberto

2016-01-01

The null Penrose inequality, i.e. the Penrose inequality in terms of the Bondi energy, is studied by introducing a functional on surfaces and studying its properties along a null hypersurface Ω extending to past null infinity. We prove a general Penrose-type inequality which involves the limit at infinity of the Hawking energy along a specific class of geodesic foliations called Geodesic Asymptotically Bondi (GAB), which are shown to always exist. Whenever this foliation approaches large spheres, this inequality becomes the null Penrose inequality and we recover the results of Ludvigsen–Vickers (1983 J. Phys. A: Math. Gen. 16 3349–53) and Bergqvist (1997 Class. Quantum Grav. 14 2577–83). By exploiting further properties of the functional along general geodesic foliations, we introduce an approach to the null Penrose inequality called the Renormalized Area Method and find a set of two conditions which imply the validity of the null Penrose inequality. One of the conditions involves a limit at infinity and the other a restriction on the spacetime curvature along the flow. We investigate their range of applicability in two particular but interesting cases, namely the shear-free and vacuum case, where the null Penrose inequality is known to hold from the results by Sauter (2008 PhD Thesis Zürich ETH ), and the case of null shells propagating in the Minkowski spacetime. Finally, a general inequality bounding the area of the quasi-local black hole in terms of an asymptotic quantity intrinsic of Ω is derived. (paper)

Jahn-Teller effect in Rydberg series: A multi-state vibronic coupling problem

International Nuclear Information System (INIS)

Staib, A.; Domcke, W.; Sobolewski, A.L.

1990-01-01

Two simple limiting cases of Jahn-Teller (JT) coupling in Rydberg states of polyatomic molecules are considered, namely (i) JT coupling in Rydberg orbitals as well as in the ionization continuum (nondegenerate ion core, degenerate Rydberg series) and (ii) JT coupling in the ion core (degenerate ion core, nondegenerate Rydberg series). For both models simple and efficient algorithms for the computation of spectra (dynamical JT effect) are developed. The orbital JT effect is shown to represent a novel type of multi-state vibronic coupling, giving rise to interesting spectroscopic phenomena, among them resonant inter-Rydberg perturbations and JT induced autoionization. Particular attention is paid to the demonstration of the characteristic spectroscopic signatures of the two types of JT coupling in Rydberg states. (orig.)

A multi-lateral trading model for coupled gas-heat-power energy networks

International Nuclear Information System (INIS)

Chen, Yue; Wei, Wei; Liu, Feng; Mei, Shengwei

2017-01-01

Highlights: •Optimal energy flows in the gas, heat, and power systems are modeled in detail. •A multi-lateral trading model for the coupled energy markets is proposed. •A two-phase algorithm for computing the market equilibrium. •Case studies demonstrate that market competition pilots reasonable energy prices. -- Abstract: The proliferation of cogeneration technology and the need for more resilient energy utilization inspire the emerging trend of integration of multi-resource energy systems, in which natural gas, heat, and electricity are produced, delivered, converted, and distributed more efficiently and flexibly. The increasing interactions and interdependencies across heterogenous physical networks impose remarkable challenges on the operation and market organization. This paper envisions the market trading scheme in the network-coupled natural gas system, district heating system, and power system. Based on the physical energy flow models of each system and their interdependency, a multi-lateral trading gas-heat-power (MLT-GHP) model is suggested, and a mixed-integer linear programming based two-phase algorithm is developed to find the market equilibrium. Case studies on two testing systems demonstrate the effectiveness of the proposed model and method, showing that the multi-lateral trading essentially results in market competition that orientates reasonable energy prices. Some prospects for future researches are also summarized.

On the null origin of the ambitwistor string

Energy Technology Data Exchange (ETDEWEB)

Casali, Eduardo [Mathematical Institute, University of Oxford,Woodstock Road, Oxford, OX2 6GG (United Kingdom); Tourkine, Piotr [Department of Applied Mathematics and Theoretical Physics,Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

2016-11-07

In this paper we present the null string origin of the ambitwistor string. Classically, the null string is the tensionless limit of string theory, and so too is the ambitwistor string. Both have as constraint algebra the Galilean Conformal Algebra in two dimensions. But something interesting happens in the quantum theory since there is an ambiguity in quantizing the null string. We show that, given a particular choice of quantization scheme and a particular gauge, the null string coincides with the ambitwistor string both classically and quantum mechanically. We also show that the same holds for the spinning versions of the null string and ambitwistor string. With these results we clarify the relationship between the ambitwistor string, the null string, the usual string and the Hohm-Siegel-Zwiebach theory.

[Dilemma of null hypothesis in ecological hypothesis's experiment test.

Science.gov (United States)

Li, Ji

2016-06-01

Experimental test is one of the major test methods of ecological hypothesis, though there are many arguments due to null hypothesis. Quinn and Dunham (1983) analyzed the hypothesis deduction model from Platt (1964) and thus stated that there is no null hypothesis in ecology that can be strictly tested by experiments. Fisher's falsificationism and Neyman-Pearson (N-P)'s non-decisivity inhibit statistical null hypothesis from being strictly tested. Moreover, since the null hypothesis H 0 (α=1, β=0) and alternative hypothesis H 1 '(α'=1, β'=0) in ecological progresses are diffe-rent from classic physics, the ecological null hypothesis can neither be strictly tested experimentally. These dilemmas of null hypothesis could be relieved via the reduction of P value, careful selection of null hypothesis, non-centralization of non-null hypothesis, and two-tailed test. However, the statistical null hypothesis significance testing (NHST) should not to be equivalent to the causality logistical test in ecological hypothesis. Hence, the findings and conclusions about methodological studies and experimental tests based on NHST are not always logically reliable.

Three genes for mitochondrial proteins suppress null-mutations in both Afg3 and Rca1 when over-expressed.

Science.gov (United States)

Rep, M; Nooy, J; Guélin, E; Grivell, L A

1996-08-01

The AFG3 gene of Saccharomyces cerevisiae encodes a mitochondrial inner membrane protein with ATP-dependent protease activity. To gain more insight into the function of this protein, multi-copy suppressors of an afg3-null mutation were isolated. Three genes were found that restored partial growth on non-fermentable carbon sources, all of which affect the biogenesis of respiratory competent mitochondria: PIM1(LON) encodes a matrix-localized ATP-dependent protease involved in the turnover of matrix proteins; OXA1(PET1402) encodes a putative mitochondrial inner membrane protein involved in the biogenesis of the respiratory chain; and MBA1 encodes a mitochondrial protein required for optimal respiratory growth. All three genes also suppressed a null mutation in a related gene, RCA1, as well as in the combination of afg3- and rca1-null.

Integrable couplings of the multi-component Dirac hierarchy and its Hamiltonian structure

International Nuclear Information System (INIS)

Li Zhu; Dong Huanhe

2008-01-01

Integrable couplings of the multi-component Dirac hierarchy is obtained by use of the vector loop algebra G ∼ M , then the Hamiltonian structure of the above system is given by the quadratic-form identity

Coupled Low-thrust Trajectory and System Optimization via Multi-Objective Hybrid Optimal Control

Science.gov (United States)

Vavrina, Matthew A.; Englander, Jacob Aldo; Ghosh, Alexander R.

2015-01-01

The optimization of low-thrust trajectories is tightly coupled with the spacecraft hardware. Trading trajectory characteristics with system parameters ton identify viable solutions and determine mission sensitivities across discrete hardware configurations is labor intensive. Local independent optimization runs can sample the design space, but a global exploration that resolves the relationships between the system variables across multiple objectives enables a full mapping of the optimal solution space. A multi-objective, hybrid optimal control algorithm is formulated using a multi-objective genetic algorithm as an outer loop systems optimizer around a global trajectory optimizer. The coupled problem is solved simultaneously to generate Pareto-optimal solutions in a single execution. The automated approach is demonstrated on two boulder return missions.

Refining multi-model projections of temperature extremes by evaluation against land-atmosphere coupling diagnostics

Science.gov (United States)

Sippel, Sebastian; Zscheischler, Jakob; Mahecha, Miguel D.; Orth, Rene; Reichstein, Markus; Vogel, Martha; Seneviratne, Sonia I.

2017-05-01

The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land-atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land-atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T) and evapotranspiration (ET) benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land-atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5) archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET) are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T-ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T-ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand, the differences between projected

Gravitational collapse of a cylindrical null shell in vacuum

Directory of Open Access Journals (Sweden)

S. Khakshournia

2008-03-01

Full Text Available   Barrabès-Israel null shell formalism is used to study the gravitational collapse of a thin cylindrical null shell in vacuum. In general the lightlike matter shell whose history coincides with a null hypersurface is characterized by a surface energy density. In addition, a gravitational impulsive wave is present on this null hypersurface whose generators admit both the shear and expansion. In the case of imposing the cylindrical flatness the surface energy-momentum tensor of the matter shell on the null hypersurface vanishes and the null hyper- surface is just the history of the gravitational wave .

Bare Quantum Null Energy Condition.

Science.gov (United States)

Fu, Zicao; Marolf, Donald

2018-02-16

The quantum null energy condition (QNEC) is a conjectured relation between a null version of quantum field theory energy and derivatives of quantum field theory von Neumann entropy. In some cases, divergences cancel between these two terms and the QNEC is intrinsically finite. We study the more general case here where they do not and argue that a QNEC can still hold for bare (unrenormalized) quantities. While the original QNEC applied only to locally stationary null congruences in backgrounds that solve semiclassical theories of quantum gravity, at least in the formal perturbation theory at a small Planck length, the quantum focusing conjecture can be viewed as the special case of our bare QNEC for which the metric is on shell.

MAGNETIC NULL POINTS IN KINETIC SIMULATIONS OF SPACE PLASMAS

International Nuclear Information System (INIS)

Olshevsky, Vyacheslav; Innocenti, Maria Elena; Cazzola, Emanuele; Lapenta, Giovanni; Deca, Jan; Divin, Andrey; Peng, Ivy Bo; Markidis, Stefano

2016-01-01

We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind, and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3–9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their cross sections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data

Higgs boson couplings in multi-doublet models with natural flavour conservation

Directory of Open Access Journals (Sweden)

Kei Yagyu

2016-12-01

Full Text Available We investigate the deviation in the couplings of the standard model (SM like Higgs boson (h with a mass of 125 GeV from the prediction of the SM in multi-doublet models within the framework where flavour changing neutral currents at the tree level are naturally forbidden. After we present the general expressions for the modified gauge and Yukawa couplings for h, we show the correlation between the deviation in the Yukawa coupling for the tau lepton hτ+τ− and that for the bottom quark hbb¯ under the assumption of a non-zero deviation in the hVV (V=W,Z couplings in two Higgs doublet models (2HDMs and three Higgs doublet models (3HDMs as simple examples. We clarify the possible allowed prediction of the deviations in the 3HDMs which cannot be explained in the 2HDMs even taking into account the one-loop electroweak corrections to the Yukawa coupling.

Numerical simulation of interior ballistic process of railgun based on the multi-field coupled model

Directory of Open Access Journals (Sweden)

Qinghua Lin

2016-04-01

Full Text Available Railgun launcher design relies on appropriate models. A multi-field coupled model of railgun launcher was presented in this paper. The 3D transient multi-field was composed of electromagnetic field, thermal field and structural field. The magnetic diffusion equations were solved by a finite-element boundary-element coupling method. The thermal diffusion equations and structural equations were solved by a finite element method. A coupled calculation was achieved by the transfer data from the electromagnetic field to the thermal and structural fields. Some characteristics of railgun shot, such as velocity skin effect, melt-wave erosion and magnetic sawing, which are generated under the condition of large-current and high-speed sliding electrical contact, were demonstrated by numerical simulation.

Final report on LDRD project : coupling strategies for multi-physics applications.

Energy Technology Data Exchange (ETDEWEB)

Hopkins, Matthew Morgan; Moffat, Harry K.; Carnes, Brian; Hooper, Russell Warren; Pawlowski, Roger P.

2007-11-01

Many current and future modeling applications at Sandia including ASC milestones will critically depend on the simultaneous solution of vastly different physical phenomena. Issues due to code coupling are often not addressed, understood, or even recognized. The objectives of the LDRD has been both in theory and in code development. We will show that we have provided a fundamental analysis of coupling, i.e., when strong coupling vs. a successive substitution strategy is needed. We have enabled the implementation of tighter coupling strategies through additions to the NOX and Sierra code suites to make coupling strategies available now. We have leveraged existing functionality to do this. Specifically, we have built into NOX the capability to handle fully coupled simulations from multiple codes, and we have also built into NOX the capability to handle Jacobi Free Newton Krylov simulations that link multiple applications. We show how this capability may be accessed from within the Sierra Framework as well as from outside of Sierra. The critical impact from this LDRD is that we have shown how and have delivered strategies for enabling strong Newton-based coupling while respecting the modularity of existing codes. This will facilitate the use of these codes in a coupled manner to solve multi-physic applications.

Refining multi-model projections of temperature extremes by evaluation against land–atmosphere coupling diagnostics

Directory of Open Access Journals (Sweden)

S. Sippel

2017-05-01

Full Text Available The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land–atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land–atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T and evapotranspiration (ET benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land–atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5 archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T–ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T–ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand

Null infinity and extremal horizons in AdS-CFT

International Nuclear Information System (INIS)

Hickling, Andrew; Wiseman, Toby; Lucietti, James

2015-01-01

We consider AdS gravity duals to CFT on background spacetimes with a null infinity. Null infinity on the conformal boundary may extend to an extremal horizon in the bulk. For example it does so for Poincaré–AdS, although does not for planar Schwarzschild–AdS. If null infinity does extend into an extremal horizon in the bulk, we show that the bulk near-horizon geometry is determined by the geometry of the boundary null infinity. Hence the ‘infra-red’ geometry of the bulk is fixed by the large scale behaviour of the CFT spacetime. In addition the boundary stress tensor must have a particular decay at null infinity. As an application, we argue that for CFT on asymptotically flat backgrounds, any static bulk dual containing an extremal horizon extending from the boundary null infinity, must have the near-horizon geometry of Poincaré–AdS. We also discuss a class of boundary null infinity that cannot extend to a bulk extremal horizon, although we give evidence that they can extend to an analogous null surface in the bulk which possesses an associated scale-invariant ‘near-geometry’. (paper)

Estimation and analysis of the short-term variations of multi-GNSS receiver differential code biases using global ionosphere maps

Science.gov (United States)

Li, Min; Yuan, Yunbin; Wang, Ningbo; Liu, Teng; Chen, Yongchang

2017-12-01

Care should be taken to minimize the adverse impact of differential code biases (DCBs) on global navigation satellite systems (GNSS)-derived ionospheric information determinations. For the sake of convenience, satellite and receiver DCB products provided by the International GNSS Service (IGS) are treated as constants over a period of 24 h (Li et al. (2014)). However, if DCB estimates show remarkable intra-day variability, the DCBs estimated as constants over 1-day period will partially account for ionospheric modeling error; in this case DCBs will be required to be estimated over shorter time period. Therefore, it is important to further gain insight into the short-term variation characteristics of receiver DCBs. In this contribution, the IGS combined global ionospheric maps and the German Aerospace Center (DLR)-provided satellite DCBs are used in the improved method to determine the multi-GNSS receiver DCBs with an hourly time resolution. The intra-day stability of the receiver DCBs is thereby analyzed in detail. Based on 1 month of data collected within the multi-GNSS experiment of the IGS, a good agreement within the receiver DCBs is found between the resulting receiver DCB estimates and multi-GNSS DCB products from the DLR at a level of 0.24 ns for GPS, 0.28 ns for GLONASS, 0.28 ns for BDS, and 0.30 ns for Galileo. Although most of the receiver DCBs are relatively stable over a 1-day period, large fluctuations (more than 9 ns between two consecutive hours) within the receiver DCBs can be found. We also demonstrate the impact of the significant short-term variations in receiver DCBs on the extraction of ionospheric total electron content (TEC), at a level of 12.96 TECu (TEC unit). Compared to daily receiver DCB estimates, the hourly DCB estimates obtained from this study can reflect the short-term variations of the DCB estimates more dedicatedly. The main conclusion is that preliminary analysis of characteristics of receiver DCB variations over short

The Importance of Proving the Null

Science.gov (United States)

Gallistel, C. R.

2009-01-01

Null hypotheses are simple, precise, and theoretically important. Conventional statistical analysis cannot support them; Bayesian analysis can. The challenge in a Bayesian analysis is to formulate a suitably vague alternative, because the vaguer the alternative is (the more it spreads out the unit mass of prior probability), the more the null is…

Perturbational treatment of spin-orbit coupling for generally applicable high-level multi-reference methods

International Nuclear Information System (INIS)

Mai, Sebastian; Marquetand, Philipp; González, Leticia; Müller, Thomas; Plasser, Felix; Lischka, Hans

2014-01-01

An efficient perturbational treatment of spin-orbit coupling within the framework of high-level multi-reference techniques has been implemented in the most recent version of the COLUMBUS quantum chemistry package, extending the existing fully variational two-component (2c) multi-reference configuration interaction singles and doubles (MRCISD) method. The proposed scheme follows related implementations of quasi-degenerate perturbation theory (QDPT) model space techniques. Our model space is built either from uncontracted, large-scale scalar relativistic MRCISD wavefunctions or based on the scalar-relativistic solutions of the linear-response-theory-based multi-configurational averaged quadratic coupled cluster method (LRT-MRAQCC). The latter approach allows for a consistent, approximatively size-consistent and size-extensive treatment of spin-orbit coupling. The approach is described in detail and compared to a number of related techniques. The inherent accuracy of the QDPT approach is validated by comparing cuts of the potential energy surfaces of acrolein and its S, Se, and Te analoga with the corresponding data obtained from matching fully variational spin-orbit MRCISD calculations. The conceptual availability of approximate analytic gradients with respect to geometrical displacements is an attractive feature of the 2c-QDPT-MRCISD and 2c-QDPT-LRT-MRAQCC methods for structure optimization and ab inito molecular dynamics simulations

Perturbational treatment of spin-orbit coupling for generally applicable high-level multi-reference methods

Energy Technology Data Exchange (ETDEWEB)

Mai, Sebastian; Marquetand, Philipp; González, Leticia [Institute of Theoretical Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna (Austria); Müller, Thomas, E-mail: th.mueller@fz-juelich.de [Institute for Advanced Simulation, Jülich Supercomputing Centre, Forschungszentrum Jülich, 52425 Jülich (Germany); Plasser, Felix [Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg (Germany); Lischka, Hans [Institute of Theoretical Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna (Austria); Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061 (United States)

2014-08-21

An efficient perturbational treatment of spin-orbit coupling within the framework of high-level multi-reference techniques has been implemented in the most recent version of the COLUMBUS quantum chemistry package, extending the existing fully variational two-component (2c) multi-reference configuration interaction singles and doubles (MRCISD) method. The proposed scheme follows related implementations of quasi-degenerate perturbation theory (QDPT) model space techniques. Our model space is built either from uncontracted, large-scale scalar relativistic MRCISD wavefunctions or based on the scalar-relativistic solutions of the linear-response-theory-based multi-configurational averaged quadratic coupled cluster method (LRT-MRAQCC). The latter approach allows for a consistent, approximatively size-consistent and size-extensive treatment of spin-orbit coupling. The approach is described in detail and compared to a number of related techniques. The inherent accuracy of the QDPT approach is validated by comparing cuts of the potential energy surfaces of acrolein and its S, Se, and Te analoga with the corresponding data obtained from matching fully variational spin-orbit MRCISD calculations. The conceptual availability of approximate analytic gradients with respect to geometrical displacements is an attractive feature of the 2c-QDPT-MRCISD and 2c-QDPT-LRT-MRAQCC methods for structure optimization and ab inito molecular dynamics simulations.

Conformal symmetry inheritance in null fluid spacetimes

International Nuclear Information System (INIS)

Tupper, B O J; Keane, A J; Hall, G S; Coley, A A; Carot, J

2003-01-01

We define inheriting conformal Killing vectors for null fluid spacetimes and find the maximum dimension of the associated inheriting Lie algebra. We show that for non-conformally flat null fluid spacetimes, the maximum dimension of the inheriting algebra is seven and for conformally flat null fluid spacetimes the maximum dimension is eight. In addition, it is shown that there are two distinct classes of non-conformally flat generalized plane wave spacetimes which possess the maximum dimension, and one class in the conformally flat case

Double null X-point operation in JET with NBI and ICRH heating

International Nuclear Information System (INIS)

Tubbing, B.; Bhatnagar, V.

1989-01-01

In this paper we report on a selection of experiments on H-modes, in 3 and 3.5MA discharges, in the double null X-point configuration. The first experiment, section 2, is an attempt to couple ICRH power to H-modes. Here we also report on a rather unique H-mode with a smaller than usual distance between plasma and limiter. The second experiment, section 3, is on H-modes in the low density, hot ion regime. (author) 5 refs., 4 figs

Computational implementation of the multi-mechanism deformation coupled fracture model for salt

International Nuclear Information System (INIS)

Koteras, J.R.; Munson, D.E.

1996-01-01

The Multi-Mechanism Deformation (M-D) model for creep in rock salt has been used in three-dimensional computations for the Waste Isolation Pilot Plant (WIPP), a potential waste, repository. These computational studies are relied upon to make key predictions about long-term behavior of the repository. Recently, the M-D model was extended to include creep-induced damage. The extended model, the Multi-Mechanism Deformation Coupled Fracture (MDCF) model, is considerably more complicated than the M-D model and required a different technology from that of the M-D model for a computational implementation

Nuclear reactor multi-physics simulations with coupled MCNP5 and STAR-CCM+

International Nuclear Information System (INIS)

Cardoni, Jeffrey Neil; Rizwan-uddin

2011-01-01

The MCNP5 Monte Carlo particle transport code has been coupled to the computational fluid dynamics code, STAR-CCM+, to provide a high fidelity multi-physics simulation tool for pressurized water nuclear reactors. The codes are executed separately and coupled externally through a Perl script. The Perl script automates the exchange of temperature, density, and volumetric heating information between the codes using ASCII text data files. Fortran90 and Java utility programs assist job automation with data post-processing and file management. The MCNP5 utility code, MAKXSF, pre-generates temperature dependent cross section libraries for the thermal feedback calculations. The MCNP5–STAR-CCM+ coupled simulation tool, dubbed MULTINUKE, was applied to a steady state, PWR cell model to demonstrate its usage and capabilities. The demonstration calculation showed reasonable results that agree with PWR values typically reported in literature. Temperature and fission reaction rate distributions were realistic and intuitive. Reactivity coefficients were also deemed reasonable in comparison to historically reported data. The demonstration problem consisted of 9,984 CFD cells and 7,489 neutronic cells. MCNP5 tallied fission energy deposition over 3,328 UO_2 cells. The coupled solution converged within eight hours and in three MULTINUKE iterations. The simulation was carried out on a 64 bit, quad core, Intel 2.8 GHz microprocessor with 1 GB RAM. The simulations on a quad core machine indicated that a massively parallelized implementation of MULTINUKE can be used to assess larger multi-million cell models. (author)

Stability of braneworlds with non-minimally coupled multi-scalar fields

Energy Technology Data Exchange (ETDEWEB)

Chen, Feng-Wei; Gu, Bao-Min [Lanzhou University, Institute of Theoretical Physics, Lanzhou (China); Lanzhou University, Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou (China); Liu, Yu-Xiao [Lanzhou University, Research Center of Gravitation, Lanzhou (China)

2018-02-15

Linear stability of braneworld models constructed with multi-scalar fields is very different from that of single-scalar field models. It is well known that both the tensor and the scalar perturbations of the latter are stable at linear level. However, in general there is no effective method to deal with the stability problem of the scalar perturbations for braneworld models constructed with non-minimally coupled multi-scalar fields. In this work we present a systematic covariant approach to deal with the scalar perturbations. By introducing the orthonormal bases in field space and making the Kaluza-Klein decomposition, we get a set of coupled Schroedinger-like equations of the scalar perturbation modes. Using the nodal theorem, we show that the result is model-dependent. For superpotential derived brane models, the scalar perturbations are stable, but there exist normalizable scalar zero modes, which will result in unacceptable fifth force on the brane. We also use this method to analyze the f(R) braneworld model with an explicit solution and find that the scalar perturbations are stable and the scalar zero modes cannot be localized on the brane, which ensures that there is no extra long-range force and the Newtonian potential on the brane can be recovered. (orig.)

Specification of the Advanced Burner Test Reactor Multi-Physics Coupling Demonstration Problem

Energy Technology Data Exchange (ETDEWEB)

Shemon, E. R. [Argonne National Lab. (ANL), Argonne, IL (United States); Grudzinski, J. J. [Argonne National Lab. (ANL), Argonne, IL (United States); Lee, C. H. [Argonne National Lab. (ANL), Argonne, IL (United States); Thomas, J. W. [Argonne National Lab. (ANL), Argonne, IL (United States); Yu, Y. Q. [Argonne National Lab. (ANL), Argonne, IL (United States)

2015-12-21

This document specifies the multi-physics nuclear reactor demonstration problem using the SHARP software package developed by NEAMS. The SHARP toolset simulates the key coupled physics phenomena inside a nuclear reactor. The PROTEUS neutronics code models the neutron transport within the system, the Nek5000 computational fluid dynamics code models the fluid flow and heat transfer, and the DIABLO structural mechanics code models structural and mechanical deformation. The three codes are coupled to the MOAB mesh framework which allows feedback from neutronics, fluid mechanics, and mechanical deformation in a compatible format.

ENERGY DISSIPATION IN MAGNETIC NULL POINTS AT KINETIC SCALES

International Nuclear Information System (INIS)

Olshevsky, Vyacheslav; Lapenta, Giovanni; Divin, Andrey; Eriksson, Elin; Markidis, Stefano

2015-01-01

We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of “intermittent turbulence” within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5–10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as the Magnetospheric Multiscale Mission

Multi-LED parallel transmission for long distance underwater VLC system with one SPAD receiver

Science.gov (United States)

Wang, Chao; Yu, Hong-Yi; Zhu, Yi-Jun; Wang, Tao; Ji, Ya-Wei

2018-03-01

In this paper, a multiple light emitting diode (LED) chips parallel transmission (Multi-LED-PT) scheme for underwater visible light communication system with one photon-counting single photon avalanche diode (SPAD) receiver is proposed. As the lamp always consists of multi-LED chips, the data rate could be improved when we drive these multi-LED chips parallel by using the interleaver-division-multiplexing technique. For each chip, the on-off-keying modulation is used to reduce the influence of clipping. Then a serial successive interference cancellation detection algorithm based on ideal Poisson photon-counting channel by the SPAD is proposed. Finally, compared to the SPAD-based direct current-biased optical orthogonal frequency division multiplexing system, the proposed Multi-LED-PT system could improve the error-rate performance and anti-nonlinearity performance significantly under the effects of absorption, scattering and weak turbulence-induced channel fading together.

An omnibus test for the global null hypothesis.

Science.gov (United States)

Futschik, Andreas; Taus, Thomas; Zehetmayer, Sonja

2018-01-01

Global hypothesis tests are a useful tool in the context of clinical trials, genetic studies, or meta-analyses, when researchers are not interested in testing individual hypotheses, but in testing whether none of the hypotheses is false. There are several possibilities how to test the global null hypothesis when the individual null hypotheses are independent. If it is assumed that many of the individual null hypotheses are false, combination tests have been recommended to maximize power. If, however, it is assumed that only one or a few null hypotheses are false, global tests based on individual test statistics are more powerful (e.g. Bonferroni or Simes test). However, usually there is no a priori knowledge on the number of false individual null hypotheses. We therefore propose an omnibus test based on cumulative sums of the transformed p-values. We show that this test yields an impressive overall performance. The proposed method is implemented in an R-package called omnibus.

Ambitwistor strings at null infinity and (subleading) soft limits

International Nuclear Information System (INIS)

Geyer, Yvonne; Lipstein, Arthur E; Mason, Lionel

2015-01-01

The relationship between BMS symmetries at null infinity and Weinberg's soft theorems for gravitons and photons together with their subleading extensions are developed using ambitwistor string theory. Ambitwistor space is the phase space of complex null geodesics in complexified space-time. We show how it can be canonically identified with the cotangent bundle of complexified null infinity. BMS symmetries of null infinity lift to give a Hamiltonian action on ambitwistor space, both in general dimension and in its twistorial four-dimensional representation. General vertex operators arise from Hamiltonians generating diffeomorphisms of ambitwistor space that determine the scattering from past to future null infinity. When a momentum eigenstate goes soft, the diffeomorphism defined by its leading and its subleading part are extended BMS generators realized in the world sheet conformal field theory of the ambitwistor string. More generally, this gives an explicit perturbative correspondence between the scattering of null geodesics and that of the gravitational field via ambitwistor string theory. (paper)

Null controllability of the viscous Camassa–Holm equation with ...

Indian Academy of Sciences (India)

In this paper, we study the null controllability of the viscous Camassa–. Holm equation on the one-dimensional torus. By using a moving distributed control, we obtain that the system is null controllable for a given data with certain regularity. Keywords. Viscous Camassa–Holm equation; null controllability; moving control;.

Two hierarchies of multi-component Kaup-Newell equations and theirs integrable couplings

International Nuclear Information System (INIS)

Zhu Fubo; Ji Jie; Zhang Jianbin

2008-01-01

Two hierarchies of multi-component Kaup-Newell equations are derived from an arbitrary order matrix spectral problem, including positive non-isospectral Kaup-Newell hierarchy and negative non-isospectral Kaup-Newell hierarchy. Moreover, new integrable couplings of the resulting Kaup-Newell soliton hierarchies are constructed by enlarging the associated matrix spectral problem

Coupling between a multi-physics workflow engine and an optimization framework

Science.gov (United States)

Di Gallo, L.; Reux, C.; Imbeaux, F.; Artaud, J.-F.; Owsiak, M.; Saoutic, B.; Aiello, G.; Bernardi, P.; Ciraolo, G.; Bucalossi, J.; Duchateau, J.-L.; Fausser, C.; Galassi, D.; Hertout, P.; Jaboulay, J.-C.; Li-Puma, A.; Zani, L.

2016-03-01

A generic coupling method between a multi-physics workflow engine and an optimization framework is presented in this paper. The coupling architecture has been developed in order to preserve the integrity of the two frameworks. The objective is to provide the possibility to replace a framework, a workflow or an optimizer by another one without changing the whole coupling procedure or modifying the main content in each framework. The coupling is achieved by using a socket-based communication library for exchanging data between the two frameworks. Among a number of algorithms provided by optimization frameworks, Genetic Algorithms (GAs) have demonstrated their efficiency on single and multiple criteria optimization. Additionally to their robustness, GAs can handle non-valid data which may appear during the optimization. Consequently GAs work on most general cases. A parallelized framework has been developed to reduce the time spent for optimizations and evaluation of large samples. A test has shown a good scaling efficiency of this parallelized framework. This coupling method has been applied to the case of SYCOMORE (SYstem COde for MOdeling tokamak REactor) which is a system code developed in form of a modular workflow for designing magnetic fusion reactors. The coupling of SYCOMORE with the optimization platform URANIE enables design optimization along various figures of merit and constraints.

Null Subjects in European and Brazilian Portuguese

Directory of Open Access Journals (Sweden)

Pilar Barbosa

2005-12-01

Full Text Available The goals of this paper are twofold: a to provide a structural account of the effects of the informal ‘Avoid Pronoun Principle’, proposed in Chomsky (1981: 65 for the Null Subject Languages (NSLs, and b to compare, in European and Brazilian Portuguese (EP and BP, the distribution of the third person pronouns in its full and null forms, to check whether in written corpora BP incorporates signs of the ongoing loss of the null subject, largely attested in its contemporary spoken language. The strong theoretical claim is that in the Romance non-NSLs the pre-verbal subject is sitting in Spec of IP, while in the Romance NSLs it is Clitic Left-Dislocated (or is extracted by A-bar movement if it belongs to a restricted set of non-referential quantified expressions. The paper provides quantitative evidence that BP is losing the properties associated with the Null Subject Parameter. In its qualitative analysis, it shows that the contrasts between EP and BP are easily accounted for if the two derivations are assumed and if the null subjects in the two varieties are considered to be of a different nature: a pronoun in EP and a pronominal anaphor in BP.

Predictive modeling of coupled multi-physics systems: II. Illustrative application to reactor physics

International Nuclear Information System (INIS)

Cacuci, Dan Gabriel; Badea, Madalina Corina

2014-01-01

Highlights: • We applied the PMCMPS methodology to a paradigm neutron diffusion model. • We underscore the main steps in applying PMCMPS to treat very large coupled systems. • PMCMPS reduces the uncertainties in the optimally predicted responses and model parameters. • PMCMPS is for sequentially treating coupled systems that cannot be treated simultaneously. - Abstract: This work presents paradigm applications to reactor physics of the innovative mathematical methodology for “predictive modeling of coupled multi-physics systems (PMCMPS)” developed by Cacuci (2014). This methodology enables the assimilation of experimental and computational information and computes optimally predicted responses and model parameters with reduced predicted uncertainties, taking fully into account the coupling terms between the multi-physics systems, but using only the computational resources that would be needed to perform predictive modeling on each system separately. The paradigm examples presented in this work are based on a simple neutron diffusion model, chosen so as to enable closed-form solutions with clear physical interpretations. These paradigm examples also illustrate the computational efficiency of the PMCMPS, which enables the assimilation of additional experimental information, with a minimal increase in computational resources, to reduce the uncertainties in predicted responses and best-estimate values for uncertain model parameters, thus illustrating how very large systems can be treated without loss of information in a sequential rather than simultaneous manner

Null-strut calculus. I. Kinematics

International Nuclear Information System (INIS)

Kheyfets, A.; LaFave, N.J.; Miller, W.A.

1990-01-01

This paper describes the kinematics of null-strut calculus---a 3+1 Regge calculus approach to general relativity. We show how to model the geometry of spacetime with simplicial spacelike three-geometries (TET's) linked to ''earlier'' and ''later'' momentumlike lattice surfaces (TET * ) entirely by light rays or ''null struts.'' These three-layered lattice spacetime geometries are defined and analyzed using combinatorial formulas for the structure of polytopes. The following paper in this series describes how these three-layered spacetime lattices are used to model spacetimes in full conformity with Einstein's theory of gravity

The EMIR multi-band mm-wave receiver for the IRAM 30-m telescope

Science.gov (United States)

Carter, M.; Lazareff, B.; Maier, D.; Chenu, J.-Y.; Fontana, A.-L.; Bortolotti, Y.; Boucher, C.; Navarrini, A.; Blanchet, S.; Greve, A.; John, D.; Kramer, C.; Morel, F.; Navarro, S.; Peñalver, J.; Schuster, K. F.; Thum, C.

2012-02-01

Aims: The prime motivation of this project was to design and build a state-of-art mm-wave heterodyne receiver system to enhance the observing throughput of the IRAM 30-m radiotelescope. More specifically, the requirements were i) state-of-art noise performance for spectroscopic observations; ii) simultaneous dual polarization and dual-frequency observing; iii) coverage of the atmospheric transmission windows from 83 to 360 GHz; iv) compact footprint and minimal maintenance. Methods: Key elements for low noise performance of heterodyne mixers are the superconducting Niobium junctions, operating at ≃4 K. These junctions are embedded in carefully designed coupling structures; furthermore, since atmospheric radiation is a significant contributor to the system noise budget, all mixers are either sideband separating or sideband rejecting. To achieve low noise, it is also essential to maximize the coupling of the receiver to the astronomical source, and to minimize the coupling to thermal radiation from the ground-based environment; this is achieved through mirror optics that realize a wavelength-independent coupling to the telescope. A flexible configuration of mirrors and frequency selective surfaces permits various combinations of frequency bands, as well as dual-load radiometric calibration. Low noise intermediate frequency amplifiers and bias electronics also play an important role in the system performance. Results: The EMIR receiver in operation at the 30 m telescope offers four frequency bands: B1: 83-117 GHz, B2: 129-174 GHz, B3: 200-267 GHz, and B4: 260-360 GHz. In each band, the two orthogonal polarizations are observed simultaneously. Dual-band combinations B1/2 B1/3, and B2/4 are available. Bands 1 and 4 (also 3 as of Nov.-2011) feature sideband separation. In dual-band configuration, including sideband separation and polarization diplexing, up to eight IF channels are delivered to the spectrometers, totaling up to 64 GHz of signal bandwidth (of which 32

A Coupled Helicopter Rotor/Fuselage Dynamics Model Using Finite Element Multi-body

Directory of Open Access Journals (Sweden)

Cheng Qi-you

2016-01-01

Full Text Available To develop a coupled rotor/flexible fuselage model for vibration reduction studies, the equation of coupled rotor-fuselage is set up based on the theory of multi-body dynamics, and the dynamic analysis model is established with the software MSC.ADMAS and MSC.NASTRAN. The frequencies and vibration acceleration responses of the system are calculated with the model of coupled rotor-fuselage, and the results are compared with those of uncoupled modeling method. Analysis results showed that compared with uncoupled model, the dynamic characteristic obtained by the model of coupled rotor-fuselage are some different. The intrinsic frequency of rotor is increased with the increase of rotational velocities. The results also show that the flying speed has obvious influence on the vibration acceleration responses of the fuselage. The vibration acceleration response in the vertical direction is much higher at the low speed and high speed flight conditions.

Shroud leakage flow models and a multi-dimensional coupling CFD (computational fluid dynamics) method for shrouded turbines

International Nuclear Information System (INIS)

Zou, Zhengping; Liu, Jingyuan; Zhang, Weihao; Wang, Peng

2016-01-01

Multi-dimensional coupling simulation is an effective approach for evaluating the flow and aero-thermal performance of shrouded turbines, which can balance the simulation accuracy and computing cost effectively. In this paper, 1D leakage models are proposed based on classical jet theories and dynamics equations, which can be used to evaluate most of the main features of shroud leakage flow, including the mass flow rate, radial and circumferential momentum, temperature and the jet width. Then, the 1D models are expanded to 2D distributions on the interface by using a multi-dimensional scaling method. Based on the models and multi-dimensional scaling, a multi-dimensional coupling simulation method for shrouded turbines is developed, in which, some boundary source and sink are set on the interface between the shroud and the main flow passage. To verify the precision, some simulations on the design point and off design points of a 1.5 stage turbine are conducted. It is indicated that the models and methods can give predictions with sufficient accuracy for most of the flow field features and will contribute to pursue deeper understanding and better design methods of shrouded axial turbines, which are the important devices in energy engineering. - Highlights: • Free and wall attached jet theories are used to model the leakage flow in shrouds. • Leakage flow rate is modeled by virtual labyrinth number and residual-energy factor. • A scaling method is applied to 1D model to obtain 2D distributions on interfaces. • A multi-dimensional coupling CFD method for shrouded turbines is proposed. • The proposed coupling method can give accurate predictions with low computing cost.

The Visible Nulling Coronagraph--Architecture Definition and Technology Development

Science.gov (United States)

Shao, Michael; Levine, B. Martin; Wallace, J. Kent; Liu, Duncan T.; Schmidtlin, Edouard; Serabyn, Eugene; Mennesson, Bertrand; Green, Joseph J.; Aguayo, Francisco; Fregoso, S. Felipe;

Heat structure coupling of CUPID and MARS for the multi-scale simulation of the passive auxiliary feedwater system

International Nuclear Information System (INIS)

Kyu Cho, Hyoung; Cho, Yun Je; Yoon, Han Young

2014-01-01

Graphical abstract: - Highlights: • PAFS is designed to replace a conventional active auxiliary feedwater system. • Multi-D T/H analysis code, CUPID was coupled with the 1-D system analysis code MARS. • The coupled CUPID and MARS was applied for the multi-scale analysis of the PAFS test facility. • The simulation result showed that the coupled code can reproduce important phenomena in PAFS. - Abstract: For the analysis of transient two-phase flows in nuclear reactor components, a three-dimensional thermal hydraulics code, named CUPID, has been developed. In the present study, the CUPID code was coupled with a system analysis code MARS in order to apply it for the multi-scale thermal-hydraulic analysis of the passive auxiliary feedwater system (PAFS). The PAFS is one of the advanced safety features adopted in the Advanced Power Reactor Plus (APR+), which is intended to completely replace the conventional active auxiliary feedwater system. For verification of the coupling and validation of the coupled code, the PASCAL test facility was simulated, which was constructed with an aim of validating the cooling and operational performance of the PAFS. The two-phase flow phenomena of the steam supply system including the condensation inside the heat exchanger tube were calculated by MARS while the natural circulation and the boil-off in the large water pool that contains the heat exchanger tube were simulated by CUPID. This paper presents the description of the PASCAL facility, the coupling method and the simulation results using the coupled code

On the mass-coupling relation of multi-scale quantum integrable models

Energy Technology Data Exchange (ETDEWEB)

Bajnok, Zoltán; Balog, János [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary); Ito, Katsushi [Department of Physics, Tokyo Institute of Technology,2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Satoh, Yuji [Institute of Physics, University of Tsukuba,1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan); Tóth, Gábor Zsolt [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary)

2016-06-13

We determine exactly the mass-coupling relation for the simplest multi-scale quantum integrable model, the homogenous sine-Gordon model with two independent mass-scales. We first reformulate its perturbed coset CFT description in terms of the perturbation of a projected product of minimal models. This representation enables us to identify conserved tensor currents on the UV side. These UV operators are then mapped via form factor perturbation theory to operators on the IR side, which are characterized by their form factors. The relation between the UV and IR operators is given in terms of the sought-for mass-coupling relation. By generalizing the Θ sum rule Ward identity we are able to derive differential equations for the mass-coupling relation, which we solve in terms of hypergeometric functions. We check these results against the data obtained by numerically solving the thermodynamic Bethe Ansatz equations, and find a complete agreement.

Numerical simulations of sheared magnetic lines at the solar null line

Science.gov (United States)

Kuźma, B.; Murawski, K.; Solov'ev, A.

2015-05-01

Aims: We perform numerical simulations of sheared magnetic lines at the magnetic null line configuration of two magnetic arcades that are settled in a gravitationally stratified and magnetically confined solar corona. Methods: We developed a general analytical model of a 2.5D solar atmospheric structure. As a particular application of this model, we adopted it for the curved magnetic field lines with an inverted Y shape that compose the null line above two magnetic arcades, which are embedded in the solar atmosphere that is specified by the realistic temperature distribution. The physical system is described by 2.5D magnetohydrodynamic equations that are numerically solved by the FLASH code. Results: The magnetic field line shearing, implemented about 200 km below the transition region, results in Alfvén and magnetoacoustic waves that are able to penetrate solar coronal regions above the magnetic null line. As a result of the coupling of these waves, partial reflection from the transition region and scattering from inhomogeneous regions the Alfvén waves experience fast attenuation on time scales comparable to their wave periods, and the physical system relaxes in time. The attenuation time grows with the large amplitude and characteristic growing time of the shearing. Conclusions: By having chosen a different magnetic flux function, the analytical model we devised can be adopted to derive equilibrium conditions for a diversity of 2.5D magnetic structures in the solar atmosphere. Movie associated to Fig. 5 is available in electronic form at http://www.aanda.org

A Comparison of Plasma Performance Between Single-Null and Double-Null Configurations During Elming H-Mode

International Nuclear Information System (INIS)

Petrie, T.W.; Fenstermacher, M.E.; Allen, S.L.; Carlstrom, T.N.; Gohil, P.; Groebner, R.J.; Greenfield, C.M.; Hyatt, A.W.; Lasnier, C.J.; La Haye, R.J.; Leonard, A.W.; Mahdavi, M.A.; Osborne, T.H.; Porter, G.D.; Rhodes, T.L.; Thomas, D.M.; Watkins, J.G.; West, W.P.; Wolf, N.S.

1999-01-01

Tokamak plasma performance generally improves with increased shaping of the plasma cross section, such as higher elongation and higher triangularity. The stronger shaping, especially higher triangularity, leads to changes in the magnetic topology of the divertor. Because there are engineering and divertor physics issues associated with changes in the details of the divertor flux geometry, especially as the configuration transitions from a single-null (SN) divertor to a marginally balanced double-null (DN) divertor, we have undertaken a systematic evaluation of the plasma characteristics as the magnetic geometry is varied, particularly with respect to (1) energy confinement, (2) the response of the plasma to deuterium gas fueling, (3) the operational density range for the ELMing H-mode, and (4) heat flux sharing by the diverters. To quantify the degree of divertor imbalance (or equivalently, to what degree the shape is double-null or single-null), we define a parameter DRSEP. DRSEP is taken as the radial distance between the upper divertor separatrix and the lower divertor separatrix, as determined at the outboard midplane. For example, if DRSEP=O, the configuration is a magnetically balanced DN; if DRSEP = +1.0 cm, the divertor configuration is biased toward the upper divertor. Three examples are shown in Fig. 1. In the following discussions, VB drift is directed toward the lower divertor

Quantum attack-resistent certificateless multi-receiver signcryption scheme.

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Huixian Li

Full Text Available The existing certificateless signcryption schemes were designed mainly based on the traditional public key cryptography, in which the security relies on the hard problems, such as factor decomposition and discrete logarithm. However, these problems will be easily solved by the quantum computing. So the existing certificateless signcryption schemes are vulnerable to the quantum attack. Multivariate public key cryptography (MPKC, which can resist the quantum attack, is one of the alternative solutions to guarantee the security of communications in the post-quantum age. Motivated by these concerns, we proposed a new construction of the certificateless multi-receiver signcryption scheme (CLMSC based on MPKC. The new scheme inherits the security of MPKC, which can withstand the quantum attack. Multivariate quadratic polynomial operations, which have lower computation complexity than bilinear pairing operations, are employed in signcrypting a message for a certain number of receivers in our scheme. Security analysis shows that our scheme is a secure MPKC-based scheme. We proved its security under the hardness of the Multivariate Quadratic (MQ problem and its unforgeability under the Isomorphism of Polynomials (IP assumption in the random oracle model. The analysis results show that our scheme also has the security properties of non-repudiation, perfect forward secrecy, perfect backward secrecy and public verifiability. Compared with the existing schemes in terms of computation complexity and ciphertext length, our scheme is more efficient, which makes it suitable for terminals with low computation capacity like smart cards.

Multi-coupling dynamic model and 3d simulation program for in-situ leaching of uranium mining

International Nuclear Information System (INIS)

Tan Kaixuan; Zeng Sheng; Sang Xiao; Sun Bing

2010-01-01

The in-situ leaching of uranium mining is a very complicated non-linear dynamic system, which involves couplings and positive/negative feedback among many factors and processes. A comprehensive, coupled multi-factors and processes dynamic model and simulation method was established to study the in-situ leaching of uranium mining. The model accounts for most coupling among various processes as following: (1) rock texture mechanics and its evolution, (2)the incremental stress rheology of rock deformation, (3) 3-D viscoelastic/ plastic multi-deformation processes, (4) hydrofracturing, (5) tensorial (anisotropic) fracture and rock permeability, (6) water-rock interactions and mass-transport (both advective and diffusive), (7) dissolution-induced chemical compaction, (8) multi-phase fluid flow. A 3-D simulation program was compiled based on Fortran and C++. An example illustrating the application of this model to simulating acidification, production and terminal stage of in situ leaching of uranium mining is presented for the some mine in Xinjiang, China. This model and program can be used for theoretical study, mine design, production management, the study of contaminant transport and restoration in groundwater of in-situ leaching of uranium mining. (authors)

Contraceptive discontinuation and switching among couples receiving integrated HIV and family planning services in Lusaka, Zambia.

Science.gov (United States)

Haddad, Lisa; Wall, Kristin M; Vwalika, Bellington; Khu, Naw Htee; Brill, Ilene; Kilembe, William; Stephenson, Rob; Chomba, Elwyn; Vwalika, Cheswa; Tichacek, Amanda; Allen, Susan

2013-10-01

To describe predictors of contraceptive method discontinuation and switching behaviours among HIV-positive couples receiving couples' voluntary HIV counselling and testing services in Lusaka, Zambia. Couples were randomized in a factorial design to two-family planning educational intervention videos, received comprehensive family planning services and were assessed every 3 months for contraceptive initiation, discontinuation and switching. We modelled factors associated with contraceptive method upgrading and downgrading via multivariate Andersen-Gill models. Most women continued the initial method selected after randomization. The highest rates of discontinuation/switching were observed for injectable contraceptive and intrauterine device users. Time to discontinuing the more effective contraceptive methods or downgrading to oral contraceptives or condoms was associated with the women's younger age, desire for more children within the next year, heavy menstrual bleeding, bleeding between periods and cystitis/dysuria. Health concerns among women about contraceptive implants and male partners not wanting more children were associated with upgrading from oral contraceptives or condoms. HIV status of the woman or the couple was not predictive of switching or stopping. We found complicated patterns of contraceptive use. The predictors of contraception switching indicate that interventions targeted to younger couples that address common contraception-related misconceptions could improve effective family planning utilization. We recommend these findings be used to increase the uptake and continuation of contraception, especially long-acting reversible contraceptive (LARC) methods, and that fertility goal based, LARC-focused family planning be offered as an integral part of HIV prevention services.

Fine art of computing nulling interferometer maps

Science.gov (United States)

Hénault, F.

2008-07-01

Spaceborne nulling interferometers are often characterized by means of their nulling ratio, which is defined as the deepest possible extinction of one target star supposed to harbor an extra-solar system. Herein is shown that another parameter, which is the transmitting efficiency of nearby bright fringes, is also of prime importance. More generally, "nulling maps" formed by the whole destructive and constructive fringe pattern projected on-sky, are found to be very sensitive on the design of some subsystems constituting the interferometer. In particular, we consider Spatial Filtering (SF) and Achromatic Phase Shifter (APS) devices, both required achieving planet detection and characterization. Consequences of the SF choice (pinhole or single-mode optical fiber) and APS properties (with or without induced pupil-flip) are discussed, for both monochromatic and polychromatic cases. Examples of numerical simulations are provided for single Bracewell interferometer, Angel cross and X-array configurations, demonstrating noticeable differences in the aspect of resulting nulling maps. It is concluded that both FS and APS designs exhibit variable capacities for serendipitous planet discovery.

Detecting the multi-spin interaction of an XY spin chain by the geometric phase of a coupled qubit

International Nuclear Information System (INIS)

Zhang, Xiu-xing; Zhang, Ai-ping; Li, Fu-li

2012-01-01

We investigate geometric phase (GP) of a qubit symmetrically coupled to a XY spin chain with three-spin interaction in a transverse magnetic field. An analytical expression for the GP is found in the weak coupling limit. It is shown that the GP displays a sharp peak or dip around the quantum phase transition point of the spin chain. Without the three-spin interaction, the GP has a peak or dip around the critical point λ=1. If the three-spin interaction exists, the peak or dip position is obviously shifted away from the original position. This result reveals that the GP may be taken as an observable to detect both the existence and strength of multi-spin interaction in a spin chain. -- Highlights: ► Analytical expression for geometric phase (GP) of a qubit coupled to a spin chain is obtained. ► Relation between GP and multi-spin interaction is investigated. ► Detection of multi-spin interaction by means of GP is proposed.

Gap junction mediated intercellular metabolite transfer in the cochlea is compromised in connexin30 null mice.

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Qing Chang

Full Text Available Connexin26 (Cx26 and connexin30 (Cx30 are two major protein subunits that co-assemble to form gap junctions (GJs in the cochlea. Mutations in either one of them are the major cause of non-syndromic prelingual deafness in humans. Because the mechanisms of cochlear pathogenesis caused by Cx mutations are unclear, we investigated effects of Cx30 null mutation on GJ-mediated ionic and metabolic coupling in the cochlea of mice. A novel flattened cochlear preparation was used to directly assess intercellular coupling in the sensory epithelium of the cochlea. Double-electrode patch clamp recordings revealed that the absence of Cx30 did not significantly change GJ conductance among the cochlear supporting cells. The preserved electrical coupling is consistent with immunolabeling data showing extensive Cx26 GJs in the cochlea of the mutant mice. In contrast, dye diffusion assays showed that the rate and extent of intercellular transfer of multiple fluorescent dyes (including a non-metabolizable D-glucose analogue, 2-NBDG among cochlear supporting cells were severely reduced in Cx30 null mice. Since the sensory epithelium in the cochlea is an avascular organ, GJ-facilitated intercellular transfer of nutrient and signaling molecules may play essential roles in cellular homeostasis. To test this possibility, NBDG was used as a tracer to study the contribution of GJs in transporting glucose into the cochlear sensory epithelium when delivered systemically. NBDG uptake in cochlear supporting cells was significantly reduced in Cx30 null mice. The decrease was also observed with GJ blockers or glucose competition, supporting the specificity of our tests. These data indicate that GJs facilitate efficient uptake of glucose in the supporting cells. This study provides the first direct experimental evidence showing that the transfer of metabolically-important molecules in cochlear supporting cells is dependent on the normal function of GJs, thereby suggesting a

Latex allergy and filaggrin null mutations

DEFF Research Database (Denmark)

Carlsen, Berit C; Meldgaard, Michael; Hamann, Dathan

2011-01-01

to aeroallergens and it is possible that filaggrin null mutations also increase the risk of latex allergy. The aim of this paper was to examine the association between filaggrin null mutations and type I latex allergy. Methods Twenty latex allergic and 24 non-latex allergic dentists and dental assistants...... in the cases in this study may not have occurred through direct skin contact but through the respiratory organs via latex proteins that are absorbed in glove powder and aerosolized...

Qualification of a Null Lens Using Image-Based Phase Retrieval

Science.gov (United States)

Bolcar, Matthew R.; Aronstein, David L.; Hill, Peter C.; Smith, J. Scott; Zielinski, Thomas P.

2012-01-01

In measuring the figure error of an aspheric optic using a null lens, the wavefront contribution from the null lens must be independently and accurately characterized in order to isolate the optical performance of the aspheric optic alone. Various techniques can be used to characterize such a null lens, including interferometry, profilometry and image-based methods. Only image-based methods, such as phase retrieval, can measure the null-lens wavefront in situ - in single-pass, and at the same conjugates and in the same alignment state in which the null lens will ultimately be used - with no additional optical components. Due to the intended purpose of a Dull lens (e.g., to null a large aspheric wavefront with a near-equal-but-opposite spherical wavefront), characterizing a null-lens wavefront presents several challenges to image-based phase retrieval: Large wavefront slopes and high-dynamic-range data decrease the capture range of phase-retrieval algorithms, increase the requirements on the fidelity of the forward model of the optical system, and make it difficult to extract diagnostic information (e.g., the system F/#) from the image data. In this paper, we present a study of these effects on phase-retrieval algorithms in the context of a null lens used in component development for the Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission. Approaches for mitigation are also discussed.

Evaluation of null-point detection methods on simulation data

Science.gov (United States)

Olshevsky, Vyacheslav; Fu, Huishan; Vaivads, Andris; Khotyaintsev, Yuri; Lapenta, Giovanni; Markidis, Stefano

2014-05-01

We model the measurements of artificial spacecraft that resemble the configuration of CLUSTER propagating in the particle-in-cell simulation of turbulent magnetic reconnection. The simulation domain contains multiple isolated X-type null-points, but the majority are O-type null-points. Simulations show that current pinches surrounded by twisted fields, analogous to laboratory pinches, are formed along the sequences of O-type nulls. In the simulation, the magnetic reconnection is mainly driven by the kinking of the pinches, at spatial scales of several ion inertial lentghs. We compute the locations of magnetic null-points and detect their type. When the satellites are separated by the fractions of ion inertial length, as it is for CLUSTER, they are able to locate both the isolated null-points, and the pinches. We apply the method to the real CLUSTER data and speculate how common are pinches in the magnetosphere, and whether they play a dominant role in the dissipation of magnetic energy.

Triadin/Junctin double null mouse reveals a differential role for Triadin and Junctin in anchoring CASQ to the jSR and regulating Ca(2+ homeostasis.

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Simona Boncompagni

Full Text Available Triadin (Tdn and Junctin (Jct are structurally related transmembrane proteins thought to be key mediators of structural and functional interactions between calsequestrin (CASQ and ryanodine receptor (RyRs at the junctional sarcoplasmic reticulum (jSR. However, the specific contribution of each protein to the jSR architecture and to excitation-contraction (e-c coupling has not been fully established. Here, using mouse models lacking either Tdn (Tdn-null, Jct (Jct-null or both (Tdn/Jct-null, we identify Tdn as the main component of periodically located anchors connecting CASQ to the RyR-bearing jSR membrane. Both proteins proved to be important for the structural organization of jSR cisternae and retention of CASQ within them, but with different degrees of impact. Our results also suggest that the presence of CASQ is responsible for the wide lumen of the jSR cisternae. Using Ca(2+ imaging and Ca(2+ selective microelectrodes we found that changes in e-c coupling, SR Ca(2+content and resting [Ca(2+] in Jct, Tdn and Tdn/Jct-null muscles are directly correlated to the effect of each deletion on CASQ content and its organization within the jSR. These data suggest that in skeletal muscle the disruption of Tdn/CASQ link has a more profound effect on jSR architecture and myoplasmic Ca(2+ regulation than Jct/CASQ association.

Inhibition of urethane-induced genotoxicity and cell proliferation in CYP2E1-null mice

International Nuclear Information System (INIS)

Hoffler, Undi; Dixon, Darlene; Peddada, Shyamal; Ghanayem, Burhan I.

2005-01-01

Urethane is a multi-site animal carcinogen and was classified as 'reasonably anticipated to be a human carcinogen.' Urethane is a fermentation by-product and found at appreciable levels in alcoholic beverages and foods such as bread and cheese. Recent work in this laboratory demonstrated for the first time that CYP2E1 is the principal enzyme responsible for urethane metabolism. The current studies were undertaken to assess the relationships between CYP2E1-mediated metabolism and urethane-induced genotoxicity and cell proliferation as determined by induction of micronucleated erythrocytes (MN) and expression of Ki-67, respectively, using CYP2E1-null and wild-type mice. Urethane was administered at 0 (vehicle), 1, 10, or 100 mg/kg/day (p.o.), 5 days/week for 6 weeks. A significant dose-dependent increase in MN was observed in wild-type mice; however, a slight increase was measured in the MN-polychromatic erythrocytes in CYP2E1-null mice treated with 100 mg/kg. A significant increase in the expression of Ki-67 was detected in the livers and the lungs (terminal bronchioles, alveoli, and bronchi) of wild-type mice administered 100 mg urethane/kg in comparison to controls. In contrast, CYP2E1-null mice administered this dose exhibited negligible alterations in Ki-67 expression in the livers and lungs compared to controls. Interestingly, while Ki-67 expression in the forestomach decreased in wild-type mice, it increased in CYP2E1-null mice. Subsequent comparative metabolism studies demonstrated that total urethane-derived radioactivity in the plasma, liver, and lung was significantly higher in CYP2E1-null versus wild-type mice and un-metabolized urethane constituted greater than 83% of the radioactivity in CYP2E1-null mice. Un-metabolized urethane was not detectable in the plasma, liver, and lung of wild-type mice. In conclusion, these data demonstrated that CYP2E1-mediated metabolism of urethane, presumably via epoxide formation, is necessary for the induction of

Enhanced direct-modulated bandwidth of 37 GHz by a multi-section laser with a coupled-cavity-injection-grating design

DEFF Research Database (Denmark)

Bach, L.; Kaiser, W.; Reithmaier, J.P.

2003-01-01

Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device.......Using a new multi-section laser concept based on a coupled-cavity-injection-grating design, the material related intrinsic 3 dB modulation bandwidth can be enhanced up to 37 GHz for a 1.5 mm long device....

Phase-space lagrangians for null spinning strings

International Nuclear Information System (INIS)

Barcelos-Neto, J.; Ruiz-Altaba, M.; Ramirez, C.

1990-01-01

The striking fact that normal-ordered null strings have the same critical dimension as their usual non-zero tension siblings can be understood from the observation that one must, in the tensionless case, keep all the conjugate momenta as independent dynamical variables, thus doubling the number of physical degrees of freedom. The fermionic momenta give rise to a second-class constraint which cannot be solved covariantly, but can be successfully incorporated into the first-class constraint algebra after gauge-fixing. The ghost contributions to the anomaly consist of two b-c (and also two β-γ systems in the supersymmetric case), of the single Virasoro sub(super)algebra for the closed null (spinning) string. In the appropriate gauge, the null (super)string is (super)chiral. (orig.)

Transmit/Receive Spatial Smoothing with Improved Effective Array Aperture for Angle and Mutual Coupling Estimation in Bistatic MIMO Radar

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Haomiao Liu

2016-01-01

Full Text Available We proposed a transmit/receive spatial smoothing with improved effective aperture approach for angle and mutual coupling estimation in bistatic MIMO radar. Firstly, the noise in each channel is restrained, by exploiting its independency, in both the spatial domain and temporal domain. Then the augmented transmit and receive spatial smoothing matrices with improved effective aperture are obtained, by exploiting the Vandermonde structure of steering vector with uniform linear array. The DOD and DOA can be estimated by utilizing the unitary ESPRIT algorithm. Finally, the mutual coupling coefficients of both the transmitter and the receiver can be figured out with the estimated angles of DOD and DOA. Numerical examples are presented to verify the effectiveness of the proposed method.

Tensionless branes and the null string critical dimension

International Nuclear Information System (INIS)

Bozhilov, P.

1998-01-01

BRST quantization is carried out for a model of p-branes with second class constraints. After extension of the phase space the constraint algebra coincides with the one of null string when p=1. It is shown that in this case one can or cannot obtain critical dimension for the null string, depending on the choice of the operator ordering and corresponding vacuum states. When p>1, operator orderings leading to critical dimension in the p=1 case are not allowed. Admissible orderings give no restrictions on the dimension of the embedding space-time. Finally, a generalization to supersymmetric null branes is proposed

Anisotropy and multi-band effects in weak-coupling superconductors

International Nuclear Information System (INIS)

Berger, T.L.

1977-01-01

The techniques of second quantization and thermodynamic Green functions are used to investigate energy gap anisotropy and multi-band effects in pure, single-crystal, weak-coupling superconductors. A generalized version of the standard Gorkov factorization is used to linearize the Green functions equations of motion. The effects of lattice periodicity and band structure are taken into account by means of Bloch wave expansions and Bloch transforms. A pairing selection rule is derived which indicates the possibility of pairing between single particle states belonging to different bands, as well as the usual Cooper pairing. It is shown that the interband gap parameter, which is coupled to the usual gap parameter by the Green functions equations of motion, can only contribute indirectly to the tunneling electric current and the thermodynamic potential. In the absence of interband pairing, the equations of motion lead to the usual BCS gap equation. Also, in the absence of interband pairing, the gap parameter is found to be equal to the diagonal matrix element of the superconductor pair potential between electronic Bloch states. An essentially temperature independent anisotropy function which contains all angular dependence of the gap is shown to evolve naturally from this formalism. The overall temperature dependence of the gap is investigated and it is found that with a change of temperature, the magnitude of the gap in different directions changes in the same ration. The ordinary Markowitz-Kadanoff model is shown to be inappropriate for the case of a multi-band superconductor and a generalized version of this model is introduced and discussed. A special case of this model is considered which leads to gap discontinuities at Brillouin zone boundaries

A simultaneous multi-slice selective J-resolved experiment for fully resolved scalar coupling information

Science.gov (United States)

Zeng, Qing; Lin, Liangjie; Chen, Jinyong; Lin, Yanqin; Barker, Peter B.; Chen, Zhong

2017-09-01

Proton-proton scalar coupling plays an important role in molecular structure elucidation. Many methods have been proposed for revealing scalar coupling networks involving chosen protons. However, determining all JHH values within a fully coupled network remains as a tedious process. Here, we propose a method termed as simultaneous multi-slice selective J-resolved spectroscopy (SMS-SEJRES) for simultaneously measuring JHH values out of all coupling networks in a sample within one experiment. In this work, gradient-encoded selective refocusing, PSYCHE decoupling and echo planar spectroscopic imaging (EPSI) detection module are adopted, resulting in different selective J-edited spectra extracted from different spatial positions. The proposed pulse sequence can facilitate the analysis of molecular structures. Therefore, it will interest scientists who would like to efficiently address the structural analysis of molecules.

Circulating CD4+CD28null T Cells May Increase the Risk of an Atherosclerotic Vascular Event Shortly after Kidney Transplantation

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Michiel G. H. Betjes

2013-01-01

Full Text Available Proinflammatory CD4+ T cells without the costimulatory molecule CD28 (CD4+CD28null T cells are expanded in patients with end-stage renal disease (ESRD and associated with atherosclerotic vascular events (AVE. In a prospective study, the number of circulating CD4+CD28null T cells was established in 295 ESRD patients prior to receiving a kidney allograft. Within the first year after transplantation, an AVE occurred in 20 patients. Univariate analysis showed that besides a history of cardiovascular disease (CVDpos, HR 8.1, , age (HR 1.04, , dyslipidaemia (HR 8.8, , and the % of CD4+CD28null T cells (HR 1.04 per % increase, 95% CI 1.00–1.09, were significantly associated with the occurrence of a posttransplantation AVE. In a multivariate analysis, only CVDpos remained a significant risk factor with a significant and positive interaction between the terms CVDpos and the % of CD4+CD28null T cells (HR 1.05, 95% CI 1.03–1.11, . Within the CVDpos group, the incidence of an AVE was 13% in the lowest tertile compared to 25% in the highest tertile of % of CD4+CD28null T cells. In conclusion, the presence of circulating CD4+CD28null T cells is associated with an increased risk for a cardiovascular event shortly after kidney transplantation.

A mathematical model for predicting photo-induced voltage and photostriction of PLZT with coupled multi-physics fields and its application

International Nuclear Information System (INIS)

Huang, J H; Wang, X J; Wang, J

2016-01-01

The primary purpose of this paper is to propose a mathematical model of PLZT ceramic with coupled multi-physics fields, e.g. thermal, electric, mechanical and light field. To this end, the coupling relationships of multi-physics fields and the mechanism of some effects resulting in the photostrictive effect are analyzed theoretically, based on which a mathematical model considering coupled multi-physics fields is established. According to the analysis and experimental results, the mathematical model can explain the hysteresis phenomenon and the variation trend of the photo-induced voltage very well and is in agreement with the experimental curves. In addition, the PLZT bimorph is applied as an energy transducer for a photovoltaic–electrostatic hybrid actuated micromirror, and the relation of the rotation angle and the photo-induced voltage is discussed based on the novel photostrictive mathematical model. (paper)

Resistivity at the field null of the FRC plasma

International Nuclear Information System (INIS)

Gerwin, R.A.

1989-01-01

In the absence of the major destructive instabilities, the configuration time is ultimately determined by particle and flux containment. If the profiles are ''gentle,'' then the anomalous flux-loss rate depends essentially on the anomalous resistivity at the field null. Conventional electrostatic quasi-linear models of anomalous cross-field resistive diffusivity are based upon the use of rvec E x rvec B drift velocities, and hence break down at the magnetic field null. In this paper, an electromagnetic treatment valid at the field null is developed, based upon the presence of flute-parity perturbations. An expression for anomalous resistivity at the field null in the quasi-linear approximation is derived by averaging in the ignorable direction over the random phases of the perturbations. The expression is valid for arbitrary (non-local) radial shapes of the perturbing modes (for example, the eigenfunctions need not be centered at the field null), and for an arbitrary ratio of real frequency to growth rate. The effective resistivity due to flute perturbations of the MHD type will be considered. 1 ref

Ultra-compact coherent receiver with serial interface for pluggable transceiver.

Science.gov (United States)

Itoh, Toshihiro; Nakajima, Fumito; Ohno, Tetsuichiro; Yamanaka, Shogo; Soma, Shunichi; Saida, Takashi; Nosaka, Hideyuki; Murata, Koichi

2014-09-22

An ultra-compact integrated coherent receiver with a volume of 1.3 cc using a quad-channel transimpedance amplifier (TIA)-IC chip with a serial peripheral interface (SPI) is demonstrated for the first time. The TIA with the SPI and photodiode (PD) bias circuits, a miniature dual polarization optical hybrid, an octal-PD and small optical coupling system enabled the realization of the compact receiver. Measured transmission performance with 32 Gbaud dual-polarization quadrature phase shift keying signal is equivalent to that of the conventional multi-source agreement-based integrated coherent receiver with dual channel TIA-ICs. By comparing the bit-error rate (BER) performance with that under continuous SPI access, we also confirmed that there is no BER degradation caused by SPI interface access. Such an ultra-compact receiver is promising for realizing a new generation of pluggable transceivers.

FAST INTEGER AMBIGUITY RESOLUTION IN GPS KINEMATIC POSITIONING USING LEFT NULL SPACE AND MULTI-TIME (INVERSE PAIRED CHOLESKY DECORRELATION

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Rong Duan

Full Text Available Aiming at the problems that huge amount of computation in ambiguity resolution with multiple epochs and high-order matrix inversion occurred in the GPS kinematic relative positioning, a modified algorithm for fast integer ambiguity resolution is proposed. Firstly, Singular Value Decomposition (SVD is applied to construct the left null space matrix in order to eliminate the baselines components, which is able to separate ambiguity parameters from the position parameters efficiently. Kalman filter is applied only to estimate the ambiguity parameters so that the real-time ambiguity float solution is obtained. Then, sorting and multi-time (inverse paired Cholesky decomposition are adopted for decorrelation of ambiguity. After diagonal elements preprocessing and diagonal elements sorting according to the results of Cholesky decomposition, the efficiency of decomposition and decorrelation is improved. Lastly, the integer search algorithm implemented in LAMBDA method is used for searching the integer ambiguity. To verify the validity and efficacy of the proposed algorithm, static and kinematic tests are carried out. Experimental results show that this algorithm has good performance of decorrelation and precision of float solution, with computation speed also increased effectively. The final positioning accuracy result with static baseline error less than 1 cm and kinematic error less than 2 cm, which indicates that it can be used for fast kinematic positioning of high precision carrier.

Coupling biomechanics to a cellular level model: an approach to patient-specific image driven multi-scale and multi-physics tumor simulation.

Science.gov (United States)

May, Christian P; Kolokotroni, Eleni; Stamatakos, Georgios S; Büchler, Philippe

2011-10-01

Modeling of tumor growth has been performed according to various approaches addressing different biocomplexity levels and spatiotemporal scales. Mathematical treatments range from partial differential equation based diffusion models to rule-based cellular level simulators, aiming at both improving our quantitative understanding of the underlying biological processes and, in the mid- and long term, constructing reliable multi-scale predictive platforms to support patient-individualized treatment planning and optimization. The aim of this paper is to establish a multi-scale and multi-physics approach to tumor modeling taking into account both the cellular and the macroscopic mechanical level. Therefore, an already developed biomodel of clinical tumor growth and response to treatment is self-consistently coupled with a biomechanical model. Results are presented for the free growth case of the imageable component of an initially point-like glioblastoma multiforme tumor. The composite model leads to significant tumor shape corrections that are achieved through the utilization of environmental pressure information and the application of biomechanical principles. Using the ratio of smallest to largest moment of inertia of the tumor material to quantify the effect of our coupled approach, we have found a tumor shape correction of 20% by coupling biomechanics to the cellular simulator as compared to a cellular simulation without preferred growth directions. We conclude that the integration of the two models provides additional morphological insight into realistic tumor growth behavior. Therefore, it might be used for the development of an advanced oncosimulator focusing on tumor types for which morphology plays an important role in surgical and/or radio-therapeutic treatment planning. Copyright © 2011 Elsevier Ltd. All rights reserved.

Novel instrument for characterizing comprehensive physical properties under multi-mechanical loads and multi-physical field coupling conditions

Science.gov (United States)

Liu, Changyi; Zhao, Hongwei; Ma, Zhichao; Qiao, Yuansen; Hong, Kun; Ren, Zhuang; Zhang, Jianhai; Pei, Yongmao; Ren, Luquan

2018-02-01

Functional materials represented by ferromagnetics and ferroelectrics are widely used in advanced sensor and precision actuation due to their special characterization under coupling interactions of complex loads and external physical fields. However, the conventional devices for material characterization can only provide a limited type of loads and physical fields and cannot simulate the actual service conditions of materials. A multi-field coupling instrument for characterization has been designed and implemented to overcome this barrier and measure the comprehensive physical properties under complex service conditions. The testing forms include tension, compression, bending, torsion, and fatigue in mechanical loads, as well as different external physical fields, including electric, magnetic, and thermal fields. In order to offer a variety of information to reveal mechanical damage or deformation forms, a series of measurement methods at the microscale are integrated with the instrument including an indentation unit and in situ microimaging module. Finally, several coupling experiments which cover all the loading and measurement functions of the instrument have been implemented. The results illustrate the functions and characteristics of the instrument and then reveal the variety in mechanical and electromagnetic properties of the piezoelectric transducer ceramic, TbDyFe alloy, and carbon fiber reinforced polymer under coupling conditions.

A Two-Dimensional Multiphysics Coupling Model of a Middle and Low Temperature Solar Receiver/Reactor for Methanol Decomposition

Directory of Open Access Journals (Sweden)

Yanjuan Wang

2017-10-01

Full Text Available Abstract: In this paper, the endothermic methanol decomposition reaction is used to obtain syngas by transforming middle and low temperature solar energy into chemical energy. A two-dimensional multiphysics coupling model of a middle and low temperature of 150~300 °C solar receiver/reactor was developed, which couples momentum equation in porous catalyst bed, the governing mass conservation with chemical reaction, and energy conservation incorporating conduction/convection/radiation heat transfer. The complex thermochemical conversion process of the middle and low temperature solar receiver/reactor (MLTSRR system was analyzed. The numerical finite element method (FEM model was validated by comparing it with the experimental data and a good agreement was obtained, revealing that the numerical FEM model is reliable. The characteristics of chemical reaction, coupled heat transfer, the components of reaction products, and the temperature fields in the receiver/reactor were also revealed and discussed. The effects of the annulus vacuum space and the glass tube on the performance of the solar receiver/reactor were further studied. It was revealed that when the direct normal irradiation increases from 200 W/m2 to 800 W/m2, the theoretical efficiency of solar energy transformed into chemical energy can reach 0.14–0.75. When the methanol feeding rate is 13 kg/h, the solar flux increases from 500 W/m2 to 1000 W/m2, methanol conversion can fall by 6.8–8.9% with air in the annulus, and methanol conversion can decrease by 21.8–28.9% when the glass is removed from the receiver/reactor.

Matter sources for a null big bang

International Nuclear Information System (INIS)

Bronnikov, K A; Zaslavskii, O B

2008-01-01

We consider the properties of stress-energy tensors compatible with a null big bang, i.e., cosmological evolution starting from a Killing horizon rather than a singularity. For Kantowski-Sachs cosmologies, it is shown that if matter satisfies the null energy condition, then (i) regular cosmological evolution can only start from a Killing horizon, (ii) matter is absent at the horizon and (iii) matter can only appear in the cosmological region due to interaction with vacuum. The latter is understood phenomenologically as a fluid whose stress tensor is insensitive to boosts in a particular direction. We also argue that matter is absent in a static region beyond the horizon. All this generalizes the observations recently obtained for a mixture of dust and a vacuum fluid. If, however, we admit the existence of phantom matter, its certain special kinds (with the parameter w ≤ -3) are consistent with a null big bang without interaction with vacuum (or without vacuum fluid at all). Then in the static region there is matter with w ≥ -1/3. Alternatively, the evolution can begin from a horizon in an infinitely remote past, leading to a scenario combining the features of a null big bang and an emergent universe

Money and Marriage: Couple's Choices and their Predictors

Directory of Open Access Journals (Sweden)

Lina Coelho

2016-01-01

Full Text Available The ways in which couples in South Europe manage their money has received little attention. This study uses regression analysis to evaluate the allocative systems of Portuguese couples and their predictors. To do this we use a sample of 3,331 households in Portugal with at least one heterosexual couple. Couples' allocative systems were classified based on Pahl's typology. The results confirm what has been found in previous studies regarding the prevalence of joint pooling management and the predictors of the different models for managing money. However, some particularities have been found: decisions taken in multi-generational familes favour partial joint pooling, as the distinctive characteristics of households in South Europe play a role in assigning intra-family resources.

Wilson loop OPE, analytic continuation and multi-Regge limit

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki

2014-05-01

We explore a direct connection between the collinear limit and the multi-Regge limit for scattering amplitudes in the N=4 super Yang-Mills theory. Starting with the collinear expansion for the six-gluon amplitude in the Euclidean kinematic region, we perform an analytic continuation term by term to the so-called Mandelstam region. We find that the result coincides with the collinear expansion of the analytically continued amplitude. We then take the multi-Regge limit, and conjecture that the final result precisely reproduces the one from the BFKL approach. Combining this procedure with the OPE for null polygonal Wilson loops, we explicitly compute the leading contribution in the ''collinear-Regge'' limit up to five loops. Our results agree with all the known results up to four loops. At five-loop, our results up to the next-to-next-to-leading logarithmic approximation (NNLLA) also reproduce the known results, and for the N 3 LLA and the N 4 LLA give non-trivial predictions. We further present an all-loop prediction for the imaginary part of the next-to-double-leading logarithmic approximation. Our procedure has a possibility of an interpolation from weak to strong coupling in the multi-Regge limit with the help of the OPE.

Tolerance analysis of null lenses using an end-use system performance criterion

Science.gov (United States)

Rodgers, J. Michael

2000-07-01

An effective method of assigning tolerances to a null lens is to determine the effects of null-lens fabrication and alignment errors on the end-use system itself, not simply the null lens. This paper describes a method to assign null- lens tolerances based on their effect on any performance parameter of the end-use system.

Generalized coupling resonance modeling, analysis, and active damping of multi-parallel inverters in microgrid operating in grid-connected mode

DEFF Research Database (Denmark)

Chen, Zhiyong; Chen, Yandong; Guerrero, Josep M.

2016-01-01

This paper firstly presents an equivalent coupling circuit modeling of multi-parallel inverters in microgrid operating in grid-connected mode. By using the model, the coupling resonance phenomena are explicitly investigated through the mathematical approach, and the intrinsic and extrinsic...

Multi-regional local anesthetic infiltration during laparoscopic cholecystectomy in patients receiving prophylactic multi-modal analgesia: a randomized, double-blinded, placebo-controlled study

DEFF Research Database (Denmark)

Bisgaard, T; Klarskov, B; Kristiansen, V B

1999-01-01

undergoing elective laparoscopic cholecystectomy. In addition, all patients received multi-modal prophylactic analgesic treatment. Fifty-eight patients were randomized to receive a total of 286 mg (66 mL) ropivacaine or 66 mL saline via periportal and intraperitoneal infiltration. During the first 3...... postoperative h, the use of morphine and antiemetics was registered, and pain and nausea were rated hourly. Daily pain intensity, pain localization, and supplemental analgesic consumption were registered the first postoperative week. Ropivacaine reduced overall pain the first two hours and incisional pain...... for the first three postoperative hours (P ropivacaine group (P

Coupled analysis of multi-impact energy harvesting from low-frequency wind induced vibrations

Science.gov (United States)

Zhu, Jin; Zhang, Wei

2015-04-01

Energy need from off-grid locations has been critical for effective real-time monitoring and control to ensure structural safety and reliability. To harvest energy from ambient environments, the piezoelectric-based energy-harvesting system has been proven very efficient to convert high frequency vibrations into usable electrical energy. However, due to the low frequency nature of the vibrations of civil infrastructures, such as those induced from vehicle impacts, wind, and waves, the application of a traditional piezoelectric-based energy-harvesting system is greatly restrained since the output power drops dramatically with the reduction of vibration frequencies. This paper focuses on the coupled analysis of a proposed piezoelectric multi-impact wind-energy-harvesting device that can effectively up-convert low frequency wind-induced vibrations into high frequency ones. The device consists of an H-shape beam and four bimorph piezoelectric cantilever beams. The H-shape beam, which can be easily triggered to vibrate at a low wind speed, is originated from the first Tacoma Narrows Bridge, which failed at wind speeds of 18.8 m s-1 in 1940. The multi-impact mechanism between the H-shape beam and the bimorph piezoelectric cantilever beams is incorporated to improve the harvesting performance at lower frequencies. During the multi-impact process, a series of sequential impacts between the H-shape beam and the cantilever beams can trigger high frequency vibrations of the cantilever beams and result in high output power with a considerably high efficiency. In the coupled analysis, the coupled structural, aerodynamic, and electrical equations are solved to obtain the dynamic response and the power output of the proposed harvesting device. A parametric study for several parameters in the coupled analysis framework is carried out including the external resistance, wind speed, and the configuration of the H-shape beam. The average harvested power for the piezoelectric cantilever

Premeiotic germ cell defect in seminiferous tubules of Atm-null testis

International Nuclear Information System (INIS)

Takubo, Keiyo; Hirao, Atsushi; Ohmura, Masako; Azuma, Masaki; Arai, Fumio; Nagamatsu, Go; Suda, Toshio

2006-01-01

Lifelong spermatogenesis is maintained by coordinated sequential processes including self-renewal of stem cells, proliferation of spermatogonial cells, meiotic division, and spermiogenesis. It has been shown that ataxia telangiectasia-mutated (ATM) is required for meiotic division of the seminiferous tubules. Here, we show that, in addition to its role in meiosis, ATM has a pivotal role in premeiotic germ cell maintenance. ATM is activated in premeiotic spermatogonial cells and the Atm-null testis shows progressive degeneration. In Atm-null testicular cells, differing from bone marrow cells of Atm-null mice, reactive oxygen species-mediated p16 Ink4a activation does not occur in Atm-null premeiotic germ cells, which suggests the involvement of different signaling pathways from bone marrow defects. Although Atm-null bone marrow undergoes p16 Ink4a -mediated cellular senescence program, Atm-null premeiotic germ cells exhibited cell cycle arrest and apoptotic elimination of premeiotic germ cells, which is different from p16 Ink4a -mediated senescence

Variational principle for gravity with null and non-null boundaries: a unified boundary counter-term

Energy Technology Data Exchange (ETDEWEB)

Parattu, Krishnamohan; Chakraborty, Sumanta; Padmanabhan, T. [IUCAA, Post Bag 4, Pune (India)

2016-03-15

It is common knowledge that the Einstein-Hilbert action does not furnish a well-posed variational principle. The usual solution to this problem is to add an extra boundary term to the action, called a counter-term, so that the variational principle becomes well-posed. When the boundary is spacelike or timelike, the Gibbons-Hawking-York counter-term is the most widely used. For null boundaries, we had proposed a counter-term in a previous paper. In this paper, we extend the previous analysis and propose a counter-term that can be used to eliminate variations of the ''off-the-surface'' derivatives of the metric on any boundary, regardless of its spacelike, timelike or null nature. (orig.)

Null geodesics and shadow of a rotating black hole in extended Chern-Simons modified gravity

International Nuclear Information System (INIS)

Amarilla, Leonardo; Eiroa, Ernesto F.; Giribet, Gaston

2010-01-01

The Chern-Simons modification to general relativity in four dimensions consists of adding to the Einstein-Hilbert term a scalar field that couples to the first-class Pontryagin density. In this theory, which has attracted considerable attention recently, the Schwarzschild metric persists as an exact solution, and this is why this model resists several observational constraints. In contrast, the spinning black hole solution of the theory is not given by the Kerr metric but by a modification of it, so far only known for slow rotation and small coupling constant. In the present paper, we show that, in this approximation, the null geodesic equation can be integrated, and this allows us to investigate the shadow cast by a black hole. We discuss how, in addition to the angular momentum of the solution, the coupling to the Chern-Simons term deforms the shape of the shadow.

Visible nulling coronagraphy testbed development for exoplanet detection

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Thompson, Patrick; Chen, Andrew; Petrone, Peter; Booth, Andrew; Madison, Timothy; Bolcar, Matthew; Noecker, M. Charley; Kendrick, Stephen; Melnick, Gary; Tolls, Volker

2010-07-01

Three of the recently completed NASA Astrophysics Strategic Mission Concept (ASMC) studies addressed the feasibility of using a Visible Nulling Coronagraph (VNC) as the prime instrument for exoplanet science. The VNC approach is one of the few approaches that works with filled, segmented and sparse or diluted aperture telescope systems and thus spans the space of potential ASMC exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies and has developed an incremental sequence of VNC testbeds to advance the this approach and the technologies associated with it. Herein we report on the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under high bandwidth closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible light nulling milestones of sequentially higher contrasts of 108, 109 and 1010 at an inner working angle of 2*λ/D and ultimately culminate in spectrally broadband (>20%) high contrast imaging. Each of the milestones, one per year, is traceable to one or more of the ASMC studies. The VNT uses a modified Mach-Zehnder nulling interferometer, modified with a modified "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. Discussed will be the optical configuration laboratory results, critical technologies and the null sensing and control approach.

Internal null controllability of a linear Schrödinger-KdV system on a bounded interval

Science.gov (United States)

Araruna, Fágner D.; Cerpa, Eduardo; Mercado, Alberto; Santos, Maurício C.

2016-01-01

The control of a linear dispersive system coupling a Schrödinger and a linear Korteweg-de Vries equation is studied in this paper. The system can be viewed as three coupled real-valued equations by taking real and imaginary parts in the Schrödinger equation. The internal null controllability is proven by using either one complex-valued control on the Schrödinger equation or two real-valued controls, one on each equation. Notice that the single Schrödinger equation is not known to be controllable with a real-valued control. The standard duality method is used to reduce the controllability property to an observability inequality, which is obtained by means of a Carleman estimates approach.

Micro-/nanoscale multi-field coupling in nonlinear photonic devices

Science.gov (United States)

Yang, Qing; Wang, Yubo; Tang, Mingwei; Xu, Pengfei; Xu, Yingke; Liu, Xu

2017-08-01

The coupling of mechanics/electronics/photonics may improve the performance of nanophotonic devices not only in the linear region but also in the nonlinear region. This review letter mainly presents the recent advances on multi-field coupling in nonlinear photonic devices. The nonlinear piezoelectric effect and piezo-phototronic effects in quantum wells and fibers show that large second-order nonlinear susceptibilities can be achieved, and second harmonic generation and electro-optic modulation can be enhanced and modulated. Strain engineering can tune the lattice structures and induce second order susceptibilities in central symmetry semiconductors. By combining the absorption-based photoacoustic effect and intensity-dependent photobleaching effect, subdiffraction imaging can be achieved. This review will also discuss possible future applications of these novel effects and the perspective of their research. The review can help us develop a deeper knowledge of the substance of photon-electron-phonon interaction in a micro-/nano- system. Moreover, it can benefit the design of nonlinear optical sensors and imaging devices with a faster response rate, higher efficiency, more sensitivity and higher spatial resolution which could be applied in environmental detection, bio-sensors, medical imaging and so on.

Meterwavelength Single-pulse Polarimetric Emission Survey. III. The Phenomenon of Nulling in Pulsars

Energy Technology Data Exchange (ETDEWEB)

Basu, Rahul; Mitra, Dipanjan; Melikidze, George I., E-mail: rahulbasu.astro@gmail.com [Janusz Gil Institute of Astronomy, University of Zielona Góra, ul. Szafrana 2, 65–516 Zielona Góra (Poland)

2017-09-10

A detailed analysis of nulling was conducted for the pulsars studied in the Meterwavelength Single-pulse Polarimetric Emission Survey. We characterized nulling in 36 pulsars including 17 pulsars where the phenomenon was reported for the first time. The most dominant nulls lasted for a short duration, less than five periods. Longer duration nulls extending to hundreds of periods were also seen in some cases. A careful analysis showed the presence of periodicities in the transition from the null to the burst states in 11 pulsars. In our earlier work, fluctuation spectrum analysis showed multiple periodicities in 6 of these 11 pulsars. We demonstrate that the longer periodicity in each case was associated with nulling. The shorter periodicities usually originate from subpulse drifting. The nulling periodicities were more aligned with the periodic amplitude modulation, indicating a possible common origin for both. The most prevalent nulls last for a single period and can be potentially explained using random variations affecting the plasma processes in the pulsar magnetosphere. On the other hand, longer-duration nulls require changes in the pair-production processes, which need an external triggering mechanism for the changes. The presence of periodic nulling puts an added constraint on the triggering mechanism, which also needs to be periodic.

Comments on correlation functions of large spin operators and null polygonal Wilson loops

Energy Technology Data Exchange (ETDEWEB)

Cardona, Carlos A., E-mail: cargicar@iafe.uba.ar [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA), C.C. 67 - Suc. 28, 1428 Buenos Aires (Argentina); Physics Department, University of Buenos Aires, CONICET, Ciudad Universitaria, 1428 Buenos Aires (Argentina)

2013-02-11

We discuss the relation between correlation functions of twist-two large spin operators and expectation values of Wilson loops along light-like trajectories. After presenting some heuristic field theoretical arguments suggesting this relation, we compute the divergent part of the correlator in the limit of large 't Hooft coupling and large spins, using a semi-classical world-sheet which asymptotically looks like a GKP rotating string. We show this diverges as expected from the expectation value of a null Wilson loop, namely, as (ln{mu}{sup -2}){sup 2}, {mu} being a cut-off of the theory.

Comments on correlation functions of large spin operators and null polygonal Wilson loops

International Nuclear Information System (INIS)

Cardona, Carlos A.

2013-01-01

We discuss the relation between correlation functions of twist-two large spin operators and expectation values of Wilson loops along light-like trajectories. After presenting some heuristic field theoretical arguments suggesting this relation, we compute the divergent part of the correlator in the limit of large 't Hooft coupling and large spins, using a semi-classical world-sheet which asymptotically looks like a GKP rotating string. We show this diverges as expected from the expectation value of a null Wilson loop, namely, as (lnμ −2 ) 2 , μ being a cut-off of the theory.

Emission and null coordinates: geometrical properties and physical construction

International Nuclear Information System (INIS)

Coll, Bartolome; Ferrando, Joan J; Morales-Lladosa, Juan A

2011-01-01

A Relativistic Positioning System is defined by four clocks (emitters) broadcasting their proper time. Then, every event reached by the signals is naturally labeled by these four times which are the emission coordinates of this event. The coordinate hypersurfaces of the emission coordinates are the future light cones based on the emitter trajectories. For this reason the emission coordinates have been also named null coordinates or light coordinates. Nevertheless, other coordinate systems used in different relativistic contexts have the own right to be named null or light coordinates. Here we analyze when one can say that a coordinate is a null coordinate and when one can say that a coordinate system is null. Moreover, we examine the physical construction and the geometrical properties of several n ull coordinate systems : the emission and the reception coordinates, the radar coordinates, and the Bondi-Sachs coordinates, among others.

Magnetoacoustic Waves in a Stratified Atmosphere with a Magnetic Null Point

Energy Technology Data Exchange (ETDEWEB)

Tarr, Lucas A.; Linton, Mark; Leake, James, E-mail: lucas.tarr.ctr@nrl.navy.mil [U.S. Naval Research Laboratory, 4555 Overlook Ave. SW, Washington, DC 20375 (United States)

2017-03-01

We perform nonlinear MHD simulations to study the propagation of magnetoacoustic waves from the photosphere to the low corona. We focus on a 2D system with a gravitationally stratified atmosphere and three photospheric concentrations of magnetic flux that produce a magnetic null point with a magnetic dome topology. We find that a single wavepacket introduced at the lower boundary splits into multiple secondary wavepackets. A portion of the packet refracts toward the null owing to the varying Alfvén speed. Waves incident on the equipartition contour surrounding the null, where the sound and Alfvén speeds coincide, partially transmit, reflect, and mode-convert between branches of the local dispersion relation. Approximately 15.5% of the wavepacket’s initial energy ( E {sub input}) converges on the null, mostly as a fast magnetoacoustic wave. Conversion is very efficient: 70% of the energy incident on the null is converted to slow modes propagating away from the null, 7% leaves as a fast wave, and the remaining 23% (0.036 E {sub input}) is locally dissipated. The acoustic energy leaving the null is strongly concentrated along field lines near each of the null’s four separatrices. The portion of the wavepacket that refracts toward the null, and the amount of current accumulation, depends on the vertical and horizontal wavenumbers and the centroid position of the wavepacket as it crosses the photosphere. Regions that refract toward or away from the null do not simply coincide with regions of open versus closed magnetic field or regions of particular field orientation. We also model wavepacket propagation using a WKB method and find that it agrees qualitatively, though not quantitatively, with the results of the numerical simulation.

A new dynamic null model for phylogenetic community structure

NARCIS (Netherlands)

Pigot, Alex L; Etienne, Rampal S

Phylogenies are increasingly applied to identify the mechanisms structuring ecological communities but progress has been hindered by a reliance on statistical null models that ignore the historical process of community assembly. Here, we address this, and develop a dynamic null model of assembly by

Fiber-Coupled Wide Field of View Optical Receiver for High Speed Space Communication

Science.gov (United States)

Suddath, Shannon N.

Research groups at NASA Glenn Research Center are interested in improving data rates on the International Space Station (ISS) using a free-space optical (FSO) link. However, known flexure of the ISS structure is expected to cause misalignment of the FSO link. Passive-control designs for mitigating misalignment are under investigation, including using a fiber-bundle for improved field of view. The designs must overcome the obstacle of coupling directly to fiber, rather than a photodetector, as NASA will maintain the use of small form-factor pluggable optical transceivers (SFPs) in the ISS network. In this thesis, a bundle-based receiver capable of coupling directly to fiber is designed, simulated, and tested in lab. Two 3-lens systems were evaluated for power performance in the lab, one with a 20 mm focal length aspheric lens and the other with a 50 mm focal length aspheric lens. The maximum output power achieved was 8 muW.

Does horizon entropy satisfy a quantum null energy conjecture?

Science.gov (United States)

Fu, Zicao; Marolf, Donald

2016-12-01

A modern version of the idea that the area of event horizons gives 4G times an entropy is the Hubeny-Rangamani causal holographic information (CHI) proposal for holographic field theories. Given a region R of a holographic QFTs, CHI computes A/4G on a certain cut of an event horizon in the gravitational dual. The result is naturally interpreted as a coarse-grained entropy for the QFT. CHI is known to be finitely greater than the fine-grained Hubeny-Rangamani-Takayanagi (HRT) entropy when \\partial R lies on a Killing horizon of the QFT spacetime, and in this context satisfies other non-trivial properties expected of an entropy. Here we present evidence that it also satisfies the quantum null energy condition (QNEC), which bounds the second derivative of the entropy of a quantum field theory on one side of a non-expanding null surface by the flux of stress-energy across the surface. In particular, we show CHI to satisfy the QNEC in 1  +  1 holographic CFTs when evaluated in states dual to conical defects in AdS3. This surprising result further supports the idea that CHI defines a useful notion of coarse-grained holographic entropy, and suggests unprecedented bounds on the rate at which bulk horizon generators emerge from a caustic. To supplement our motivation, we include an appendix deriving a corresponding coarse-grained generalized second law for 1  +  1 holographic CFTs perturbatively coupled to dilaton gravity.

Continuous development of current sheets near and away from magnetic nulls

International Nuclear Information System (INIS)

Kumar, Sanjay; Bhattacharyya, R.

2016-01-01

The presented computations compare the strength of current sheets which develop near and away from the magnetic nulls. To ensure the spontaneous generation of current sheets, the computations are performed congruently with Parker's magnetostatic theorem. The simulations evince current sheets near two dimensional and three dimensional magnetic nulls as well as away from them. An important finding of this work is in the demonstration of comparative scaling of peak current density with numerical resolution, for these different types of current sheets. The results document current sheets near two dimensional magnetic nulls to have larger strength while exhibiting a stronger scaling than the current sheets close to three dimensional magnetic nulls or away from any magnetic null. The comparative scaling points to a scenario where the magnetic topology near a developing current sheet is important for energetics of the subsequent reconnection.

Null-plane quantization of fermions

International Nuclear Information System (INIS)

Mustaki, D.

1990-01-01

Massive Dirac fermions are canonically quantized on the null plane using the Dirac-Bergmann algorithm. The procedure is carried out in the framework of quantum electrodynamics as an illustration of a rigorous treatment of interacting fermion fields

Calculations of non-adiabatic couplings within equation-of-motion coupled-cluster framework: Theory, implementation, and validation against multi-reference methods

Science.gov (United States)

Faraji, Shirin; Matsika, Spiridoula; Krylov, Anna I.

2018-01-01

We report an implementation of non-adiabatic coupling (NAC) forces within the equation-of-motion coupled-cluster with single and double excitations (EOM-CCSD) framework via the summed-state approach. Using illustrative examples, we compare NAC forces computed with EOM-CCSD and multi-reference (MR) wave functions (for selected cases, we also consider configuration interaction singles). In addition to the magnitude of the NAC vectors, we analyze their direction, which is important for the calculations of the rate of non-adiabatic transitions. Our benchmark set comprises three doublet radical-cations (hexatriene, cyclohexadiene, and uracil), neutral uracil, and sodium-doped ammonia clusters. When the characters of the states agree among different methods, we observe good agreement between the respective NAC vectors, both in the Franck-Condon region and away. In the cases of large discrepancies between the methods, the disagreement can be attributed to the difference in the states' character, which, in some cases, is very sensitive to electron correlation, both within single-reference and multi-reference frameworks. The numeric results confirm that the accuracy of NAC vectors depends critically on the quality of the underlying wave functions. Within their domain of applicability, EOM-CC methods provide a viable alternative to MR approaches.

Spatial layout optimization design of multi-type LEDs lighting source based on photoelectrothermal coupling theory

Science.gov (United States)

Xue, Lingyun; Li, Guang; Chen, Qingguang; Rao, Huanle; Xu, Ping

2018-03-01

Multiple LED-based spectral synthesis technology has been widely used in the fields of solar simulator, color mixing, and artificial lighting of plant factory and so on. Generally, amounts of LEDs are spatially arranged with compact layout to obtain the high power density output. Mutual thermal spreading among LEDs will produce the coupled thermal effect which will additionally increase the junction temperature of LED. Affected by the Photoelectric thermal coupling effect of LED, the spectrum of LED will shift and luminous efficiency will decrease. Correspondingly, the spectral synthesis result will mismatch. Therefore, thermal management of LED spatial layout plays an important role for multi-LEDs light source system. In the paper, the thermal dissipation network topology model considering the mutual thermal spreading effect among the LEDs is proposed for multi-LEDs system with various types of power. The junction temperature increment cased by the thermal coupling has the great relation with the spatial arrangement. To minimize the thermal coupling effect, an optimized method of LED spatial layout for the specific light source structure is presented and analyzed. The results showed that layout of LED with high-power are arranged in the corner and low-power in the center. Finally, according to this method, it is convenient to determine the spatial layout of LEDs in a system having any kind of light source structure, and has the advantages of being universally applicable to facilitate adjustment.

Frequency Splitting Elimination and Cross-Coupling Rejection of Wireless Power Transfer to Multiple Dynamic Receivers

Directory of Open Access Journals (Sweden)

Narayanamoorthi R.

2018-01-01

Full Text Available Simultaneous power transfer to multiple receiver (Rx system is one of the key advantages of wireless power transfer (WPT system using magnetic resonance. However, determining the optimal condition to uniformly transfer the power to a selected Rx at high efficiency is the challenging task under the dynamic environment. The cross-coupling and frequency splitting are the dominant issues present in the multiple Rx dynamic WPT system. The existing analysis is performed by considering any one issue present in the system; on the other hand, the cross coupling and frequency splitting issues are interrelated in dynamic Rx’s, which requires a comprehensive design strategy by considering both the problems. This paper proposes an optimal design of multiple Rx WPT system, which can eliminate cross coupling, frequency splitting issues and increase the power transfer efficiency (PTE of selected Rx. The cross-coupling rejection, uniform power transfer is performed by adding an additional relay coil and independent resonance frequency tuning with capacitive compensation to each Rx unit. The frequency splitting phenomena are eliminated using non-identical transmitter (Tx and Rx coil structure which can maintain the coupling between the coil under the critical coupling limit. The mathematical analysis of the compensation capacitance calculation and optimal Tx coil size identification is performed for the four Rx WPT system. Finite element analysis and experimental investigation are carried out for the proposed design in static and dynamic conditions.

Detection of long nulls in PSR B1706-16, a pulsar with large timing irregularities

Science.gov (United States)

Naidu, Arun; Joshi, Bhal Chandra; Manoharan, P. K.; Krishnakumar, M. A.

2018-04-01

Single pulse observations, characterizing in detail, the nulling behaviour of PSR B1706-16 are being reported for the first time in this paper. Our regular long duration monitoring of this pulsar reveals long nulls of 2-5 h with an overall nulling fraction of 31 ± 2 per cent. The pulsar shows two distinct phases of emission. It is usually in an active phase, characterized by pulsations interspersed with shorter nulls, with a nulling fraction of about 15 per cent, but it also rarely switches to an inactive phase, consisting of long nulls. The nulls in this pulsar are concurrent between 326.5 and 610 MHz. Profile mode changes accompanied by changes in fluctuation properties are seen in this pulsar, which switches from mode A before a null to mode B after the null. The distribution of null durations in this pulsar is bimodal. With its occasional long nulls, PSR B1706-16 joins the small group of intermediate nullers, which lie between the classical nullers and the intermittent pulsars. Similar to other intermediate nullers, PSR B1706-16 shows high timing noise, which could be due to its rare long nulls if one assumes that the slowdown rate during such nulls is different from that during the bursts.

Euclidean null controllability of nonlinear infinite delay systems with ...

African Journals Online (AJOL)

Sufficient conditions for the Euclidean null controllability of non-linear delay systems with time varying multiple delays in the control and implicit derivative are derived. If the uncontrolled system is uniformly asymptotically stable and if the control system is controllable, then the non-linear infinite delay system is Euclidean null ...

Integrated approach for fusion multi-physics coupled analyses based on hybrid CAD and mesh geometries

Energy Technology Data Exchange (ETDEWEB)

Qiu, Yuefeng, E-mail: yuefeng.qiu@kit.edu; Lu, Lei; Fischer, Ulrich

2015-10-15

Highlights: • Integrated approach for neutronics, thermal and structural analyses was developed. • MCNP5/6, TRIPOLI-4 were coupled with CFX, Fluent and ANSYS Workbench. • A novel meshing approach has been proposed for describing MC geometry. - Abstract: Coupled multi-physics analyses on fusion reactor devices require high-fidelity neutronic models, and flexible, accurate data exchanging between various calculation codes. An integrated coupling approach has been developed to enable the conversion of CAD, mesh, or hybrid geometries for Monte Carlo (MC) codes MCNP5/6, TRIPOLI-4, and translation of nuclear heating data for CFD codes Fluent, CFX and structural mechanical software ANSYS Workbench. The coupling approach has been implemented based on SALOME platform with CAD modeling, mesh generation and data visualization capabilities. A novel meshing approach has been developed for generating suitable meshes for MC geometry descriptions. The coupling approach has been concluded to be reliable and efficient after verification calculations of several application cases.

Current bistability in a weakly coupled multi-quantum well structure: a magnetic field induced 'memory effect'

International Nuclear Information System (INIS)

Feu, W H M; Villas-Boas, J M; Cury, L A; Guimaraes, P S S; Vieira, G S; Tanaka, R Y; Passaro, A; Pires, M P; Landi, S M; Souza, P L

2009-01-01

A study of magnetotunnelling in weakly coupled multi-quantum wells reveals a new phenomenon which constitutes a kind of memory effect in the sense that the electrical resistance of the sample after application of the magnetic field is different from before and contains the information that a magnetic field was applied previously. The change in the electric field domain configuration triggered by the magnetic field was compared for two samples, one strictly periodic and another with a thicker quantum well inserted into the periodic structure. For applied biases at which two electric field domains are present in the sample, as the magnetic field is increased a succession of discontinuous reductions in the electrical resistance is observed due to the magnetic field-induced rearrangement of the electric field domains, i.e. the domain boundary jumps from well to well as the magnetic field is changed. The memory effect is revealed for the aperiodic structure as the electric field domain configuration triggered by the magnetic field remains stable after the field is reduced back to zero. This effect is related to the multi-stability in the current-voltage characteristics observed in some weakly coupled multi-quantum well structures.

Visual and Plastic Arts in Teaching Literacy: Null Curricula?

Science.gov (United States)

Wakeland, Robin Gay

2010-01-01

Visual and plastic arts in contemporary literacy instruction equal null curricula. Studies show that painting and sculpture facilitate teaching reading and writing (literacy), yet such pedagogy has not been formally adopted into USA curriculum. An example of null curriculum can be found in late 19th - early 20th century education the USA…

On the Robinson theorem and shearfree geodesic null congruences

International Nuclear Information System (INIS)

Tafel, J.

1985-01-01

Null electromagnetic fields and shearfree geodesic null congruences in curved and flat spacetimes are studied. We point out some mathematical problems connected with the validity of the Robinson theorem. The problem of finding nonanalytic twisting congruences in the Minkowski space is reduced to the construction of holomorphic functions with specific boundary conditions. (orig.)

Information-Theoretic Limits on Broadband Multi-Antenna Systems in the Presence of Mutual Coupling

Science.gov (United States)

Taluja, Pawandeep Singh

2011-12-01

Multiple-input, multiple-output (MIMO) systems have received considerable attention over the last decade due to their ability to provide high throughputs and mitigate multipath fading effects. While most of these benefits are obtained for ideal arrays with large separation between the antennas, practical devices are often constrained in physical dimensions. With smaller inter-element spacings, signal correlation and mutual coupling between the antennas start to degrade the system performance, thereby limiting the deployment of a large number of antennas. Various studies have proposed transceiver designs based on optimal matching networks to compensate for this loss. However, such networks are considered impractical due to their multiport structure and sensitivity to the RF bandwidth of the system. In this dissertation, we investigate two aspects of compact transceiver design. First, we consider simpler architectures that exploit coupling between the antennas, and second, we establish information-theoretic limits of broadband communication systems with closely-spaced antennas. We begin with a receiver model of a diversity antenna selection system and propose novel strategies that make use of inactive elements by virtue of mutual coupling. We then examine the limits on the matching efficiency of a single antenna system using broadband matching theory. Next, we present an extension to this theory for coupled MIMO systems to elucidate the impact of coupling on the RF bandwidth of the system, and derive optimal transceiver designs. Lastly, we summarize the main findings of this dissertation and suggest open problems for future work.

Losses at magnetic nulls in pulsed-power transmission line systems

International Nuclear Information System (INIS)

Mendel, C.W. Jr.; Pointon, T.D.; Savage, M.E.; Seidel, D.B.; Magne, I.; Vezinet, R.

2006-01-01

Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to the magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms of the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds

Current singularities at finitely compressible three-dimensional magnetic null points

International Nuclear Information System (INIS)

Pontin, D.I.; Craig, I.J.D.

2005-01-01

The formation of current singularities at line-tied two- and three-dimensional (2D and 3D, respectively) magnetic null points in a nonresistive magnetohydrodynamic environment is explored. It is shown that, despite the different separatrix structures of 2D and 3D null points, current singularities may be initiated in a formally equivalent manner. This is true no matter whether the collapse is triggered by flux imbalance within closed, line-tied null points or driven by externally imposed velocity fields in open, incompressible geometries. A Lagrangian numerical code is used to investigate the finite amplitude perturbations that lead to singular current sheets in collapsing 2D and 3D null points. The form of the singular current distribution is analyzed as a function of the spatial anisotropy of the null point, and the effects of finite gas pressure are quantified. It is pointed out that the pressure force, while never stopping the formation of the singularity, significantly alters the morphology of the current distribution as well as dramatically weakening its strength. The impact of these findings on 2D and 3D magnetic reconnection models is discussed

Null but not void: considerations for hypothesis testing.

Science.gov (United States)

Shaw, Pamela A; Proschan, Michael A

2013-01-30

Standard statistical theory teaches us that once the null and alternative hypotheses have been defined for a parameter, the choice of the statistical test is clear. Standard theory does not teach us how to choose the null or alternative hypothesis appropriate to the scientific question of interest. Neither does it tell us that in some cases, depending on which alternatives are realistic, we may want to define our null hypothesis differently. Problems in statistical practice are frequently not as pristinely summarized as the classic theory in our textbooks. In this article, we present examples in statistical hypothesis testing in which seemingly simple choices are in fact rich with nuance that, when given full consideration, make the choice of the right hypothesis test much less straightforward. Published 2012. This article is a US Government work and is in the public domain in the USA.

Toll-like receptor 4 mutant and null mice retain morphine-induced tolerance, hyperalgesia, and physical dependence.

Directory of Open Access Journals (Sweden)

Theresa Alexandra Mattioli

Full Text Available The innate immune system modulates opioid-induced effects within the central nervous system and one target that has received considerable attention is the toll-like receptor 4 (TLR4. Here, we examined the contribution of TLR4 in the development of morphine tolerance, hyperalgesia, and physical dependence in two inbred mouse strains: C3H/HeJ mice which have a dominant negative point mutation in the Tlr4 gene rendering the receptor non-functional, and B10ScNJ mice which are TLR4 null mutants. We found that neither acute antinociceptive response to a single dose of morphine, nor the development of analgesic tolerance to repeated morphine treatment, was affected by TLR4 genotype. Likewise, opioid induced hyperalgesia and opioid physical dependence (assessed by naloxone precipitated withdrawal were not altered in TLR4 mutant or null mice. We also examined the behavioural consequence of two stereoisomers of naloxone: (- naloxone, an opioid receptor antagonist, and (+ naloxone, a purported antagonist of TLR4. Both stereoisomers of naloxone suppressed opioid induced hyperalgesia in wild-type control, TLR4 mutant, and TLR4 null mice. Collectively, our data suggest that TLR4 is not required for opioid-induced analgesic tolerance, hyperalgesia, or physical dependence.

Vacuum non-expanding horizons and shear-free null geodesic congruences

International Nuclear Information System (INIS)

Adamo, T M; Newman, E T

2009-01-01

We investigate the geometry of a particular class of null surfaces in spacetime called vacuum non-expanding horizons (NEHs). Using the spin-coefficient equation, we provide a complete description of the horizon geometry, as well as fixing a canonical choice of null tetrad and coordinates on a NEH. By looking for particular classes of null geodesic congruences which live exterior to NEHs but have the special property that their shear vanishes at the intersection with the horizon, a good cut formalism for NEHs is developed which closely mirrors asymptotic theory. In particular, we show that such null geodesic congruences are generated by arbitrary choice of a complex worldline in a complex four-dimensional space, each such choice induces a CR structure on the horizon, and a particular worldline (and hence CR structure) may be chosen by transforming to a privileged tetrad frame.

Modulational instability, beak-shaped rogue waves, multi-dark-dark solitons and dynamics in pair-transition-coupled nonlinear Schrödinger equations.

Science.gov (United States)

Zhang, Guoqiang; Yan, Zhenya; Wen, Xiao-Yong

2017-07-01

The integrable coupled nonlinear Schrödinger equations with four-wave mixing are investigated. We first explore the conditions for modulational instability of continuous waves of this system. Secondly, based on the generalized N -fold Darboux transformation (DT), beak-shaped higher-order rogue waves (RWs) and beak-shaped higher-order rogue wave pairs are derived for the coupled model with attractive interaction in terms of simple determinants. Moreover, we derive the simple multi-dark-dark and kink-shaped multi-dark-dark solitons for the coupled model with repulsive interaction through the generalizing DT. We explore their dynamics and classifications by different kinds of spatial-temporal distribution structures including triangular, pentagonal, 'claw-like' and heptagonal patterns. Finally, we perform the numerical simulations to predict that some dark solitons and RWs are stable enough to develop within a short time. The results would enrich our understanding on nonlinear excitations in many coupled nonlinear wave systems with transition coupling effects.

High-contrast Nulling Interferometry Techniques Project

Data.gov (United States)

National Aeronautics and Space Administration — "We are developing rotating-baseline nulling-interferometry techniques and algorithms on the single-aperture Hale and Keck telescopes at near-infrared wavelengths,...

A model for electron currents near a field null

International Nuclear Information System (INIS)

Stark, R.A.; Miley, G.H.

1987-01-01

The fluid approximation is invalid near a field null, since the local electron orbit size and the magnetic scale length are comparable. To model the electron currents in this region we propose a single equation of motion describing the bulk electron dynamics. The equation applies to the plasma within one thermal orbit size of the null. The region is treated as unmagnetized; electrons are accelerated by the inductive electric field and drag on ions; damping is provided by viscosity due to electrons and collisions with ions. Through variational calculations and a particle tracking code for electrons, the size of the terms in the equation of motion have been estimated. The resulting equation of motion combines with Faraday's Law to produce a governing equation which implicitly contains the self inductive field of the electrons. This governing equation predicts that viscosity prevents complete cancellation of the ion current density by the electrons in the null region. Thus electron dynamics near the field null should not prevent the formation and deepening of field reversal using neutral-beam injection

Low Complexity Receiver Design for MIMO-Radar

KAUST Repository

Ahmed, Sajid

2012-09-08

In this work, an algorithm for the multiple-input multiple-output (MIMO) radar is proposed. It has low computational complexity compared to the available schemes, and relatively low side-lobe-levels in the receive beampattern compared to the phased-array and MIMO-radar. In the proposed algorithm, the received signal vector of MIMO-radar is divided into sub-vectors, and each sub-vector is multiplied with the corresponding weight vector. The number of sub-vectors and weight vectors are optimally found to maximise the received signal power from the target of interest direction. The proposed scheme can be effectively applied in passive radars to minimise the side-lobe levels and place deep nulls for interferers in the receive beampattern. Simulation results show that the proposed scheme has relatively lower side lobe levels and better detection capabilities compared to MIMO-radar and phased-array.

Low Complexity Receiver Design for MIMO-Radar

KAUST Repository

Ahmed, Sajid; Alouini, Mohamed-Slim

2012-01-01

In this work, an algorithm for the multiple-input multiple-output (MIMO) radar is proposed. It has low computational complexity compared to the available schemes, and relatively low side-lobe-levels in the receive beampattern compared to the phased-array and MIMO-radar. In the proposed algorithm, the received signal vector of MIMO-radar is divided into sub-vectors, and each sub-vector is multiplied with the corresponding weight vector. The number of sub-vectors and weight vectors are optimally found to maximise the received signal power from the target of interest direction. The proposed scheme can be effectively applied in passive radars to minimise the side-lobe levels and place deep nulls for interferers in the receive beampattern. Simulation results show that the proposed scheme has relatively lower side lobe levels and better detection capabilities compared to MIMO-radar and phased-array.

ISCO and Principal Null Congruences in Extremal Kerr Spacetime

International Nuclear Information System (INIS)

Pradhan, Parthapratim

2012-01-01

The effective potential in universal like coordinates(U, V, θ, φ), which are smooth across the event horizon is derived and investigated the ISCO(Innermost Stable Circular Orbits) explicitly in these coordinates for extremal Kerr spacetime. Extremization of the effective potential for timelike circular orbit shows that the existence of a stable circular geodesics in the extremal spacetime for direct orbit, precisely on the event horizon in terms of the radial coordinate which coincides with the principal null geodesic congruences of the event horizon. These null geodesic congruences mold themselves to the spacetime curvature in such a way that Weyl conformal tensor and its dual are vanished, that is why they are in-fact doubly degenerate principal null congruences.

Design of multi-energy Helds coupling testing system of vertical axis wind power system

Science.gov (United States)

Chen, Q.; Yang, Z. X.; Li, G. S.; Song, L.; Ma, C.

2016-08-01

The conversion efficiency of wind energy is the focus of researches and concerns as one of the renewable energy. The present methods of enhancing the conversion efficiency are mostly improving the wind rotor structure, optimizing the generator parameters and energy storage controller and so on. Because the conversion process involves in energy conversion of multi-energy fields such as wind energy, mechanical energy and electrical energy, the coupling effect between them will influence the overall conversion efficiency. In this paper, using system integration analysis technology, a testing system based on multi-energy field coupling (MEFC) of vertical axis wind power system is proposed. When the maximum efficiency of wind rotor is satisfied, it can match to the generator function parameters according to the output performance of wind rotor. The voltage controller can transform the unstable electric power to the battery on the basis of optimizing the parameters such as charging times, charging voltage. Through the communication connection and regulation of the upper computer system (UCS), it can make the coupling parameters configure to an optimal state, and it improves the overall conversion efficiency. This method can test the whole wind turbine (WT) performance systematically and evaluate the design parameters effectively. It not only provides a testing method for system structure design and parameter optimization of wind rotor, generator and voltage controller, but also provides a new testing method for the whole performance optimization of vertical axis wind energy conversion system (WECS).

Singular Null Hypersurfaces in General Relativity

International Nuclear Information System (INIS)

Dray, T

2006-01-01

Null hypersurfaces are a mathematical consequence of the Lorentzian signature of general relativity; singularities in mathematical models usually indicate where the interesting physics takes place. This book discusses what happens when you combine these ideas. Right from the preface, this is a no-nonsense book. There are two principal approaches to singular shells, one distributional and the other 'cut and paste'; both are treated in detail. A working knowledge of GR is assumed, including familiarity with null tetrads, differential forms, and 3 + 1 decompositions. Despite my own reasonably extensive, closely related knowledge, there was material unfamiliar to me already in chapter 3, although I was reunited with some old friends in later chapters. The exposition is crisp, with a minimum of transition from chapter to chapter. In fact, my main criticism is that there is no clear statement of the organization of the book, nor is there an index. Everything is here, and the story is compelling if you know what to look for, although it is less easy to follow the story if you are not already familiar with it. But this is really a book for experts, and the authors certainly qualify, having played a significant role in developing and extending the results they describe. It is also entirely appropriate that the book is dedicated to Werner Israel, who pioneered the thin-shell approach to (non-null) singular surfaces and later championed the use of similar methods for analysing null shells. After an introductory chapter on impulsive signals, the authors show how the Bianchi identities can be used to classify spacetimes with singular null hypersurfaces. This approach, due to the authors, generalizes the framework originally proposed by Penrose. While astrophysical applications are discussed only briefly, the authors point out that detailed physical characteristics of signals from isolated sources can be determined in this manner. In particular, they describe the behaviour of

The Research of Regression Method for Forecasting Monthly Electricity Sales Considering Coupled Multi-factor

Science.gov (United States)

Wang, Jiangbo; Liu, Junhui; Li, Tiantian; Yin, Shuo; He, Xinhui

2018-01-01

The monthly electricity sales forecasting is a basic work to ensure the safety of the power system. This paper presented a monthly electricity sales forecasting method which comprehensively considers the coupled multi-factors of temperature, economic growth, electric power replacement and business expansion. The mathematical model is constructed by using regression method. The simulation results show that the proposed method is accurate and effective.

Printed freeform lens arrays on multi-core fibers for highly efficient coupling in astrophotonic systems.

Science.gov (United States)

Dietrich, Philipp-Immanuel; Harris, Robert J; Blaicher, Matthias; Corrigan, Mark K; Morris, Tim M; Freude, Wolfgang; Quirrenbach, Andreas; Koos, Christian

2017-07-24

Coupling of light into multi-core fibers (MCF) for spatially resolved spectroscopy is of great importance to astronomical instrumentation. To achieve high coupling efficiencies along with fill-fractions close to unity, micro-optical elements are required to concentrate the incoming light to the individual cores of the MCF. In this paper we demonstrate facet-attached lens arrays (LA) fabricated by two-photon polymerization. The LA provide close to 100% fill-fraction along with efficiencies of up to 73% (down to 1.4 dB loss) for coupling of light from free space into an MCF core. We show the viability of the concept for astrophotonic applications by integrating an MCF-LA assembly in an adaptive-optics test bed and by assessing its performance as a tip/tilt sensor.

Demonstrating Broadband Billion-to-One Contrast with the Visible Nulling Coronagraph

Science.gov (United States)

Hicks, Brian A.; Lyon, Richard G.; Petrone, Peter, III; Miller, Ian J.; Bolcar, Matthew R.; Clampin, Mark; Helmbrecht, Michael A.; Mallik, Udayan

2015-01-01

The key to broadband operation of the Visible Nulling Coronagraph (VNC) is achieving a condition of quasi- achromatic destructive interference between combined beams. Here we present efforts towards meeting this goal using Fresnel rhombs in each interferometric arm as orthogonally aligned half wave phase retarders. The milestone goal of the demonstration is to achieve 1 × 10-9 contrast at 2/D over a 40 nm bandpass centered at 633 nm. Rhombs have been designed and fabricated, and a multi-step approach to alignment using coarse positioners for each rhomb and pair has been developed to get within range of piezo stages used for fine positioning. The previously demonstrated narrowband VNC sensing and control approach that uses a segmented deformable mirror is being adapted to broadband to include fine positioning of the piezo-mounted rhombs, all demonstrated in a low-pressure environment.

Demonstrating broadband billion-to-one contrast with the Visible Nulling Coronagraph

Science.gov (United States)

Hicks, Brian A.; Lyon, Richard G.; Petrone, Peter; Miller, Ian J.; Bolcar, Matthew R.; Clampin, Mark; Helmbrecht, Michael A.; Mallik, Udayan

2015-09-01

The key to broadband operation of the Visible Nulling Coronagraph (VNC) is achieving a condition of quasi-achromatic destructive interference between combined beams. Here we present efforts towards meeting this goal using Fresnel rhombs in each interferometric arm as orthogonally aligned half wave phase retarders. The milestone goal of the demonstration is to achieve 1 × 10-9 contrast at 2λ/D over a 40 nm bandpass centered at 633 nm. Rhombs have been designed and fabricated, and a multi-step approach to alignment using coarse positioners for each rhomb and pair has been developed to get within range of piezo stages used for fine positioning. The previously demonstrated narrowband VNC sensing and control approach that uses a segmented deformable mirror is being adapted to broadband to include fine positioning of the piezo-mounted rhombs, all demonstrated in a low-pressure environment.

Sequential weak continuity of null Lagrangians at the boundary

Czech Academy of Sciences Publication Activity Database

Kalamajska, A.; Kraemer, S.; Kružík, Martin

2014-01-01

Roč. 49, 3/4 (2014), s. 1263-1278 ISSN 0944-2669 R&D Projects: GA ČR GAP201/10/0357 Institutional support: RVO:67985556 Keywords : null Lagrangians * nonhomogeneous nonlinear mappings * sequential weak/in measure continuity Subject RIV: BA - General Mathematics Impact factor: 1.518, year: 2014 http://library.utia.cas.cz/separaty/2013/MTR/kruzik-sequential weak continuity of null lagrangians at the boundary.pdf

A parameter set for a double-null DEMO reactor

International Nuclear Information System (INIS)

Cooke, P.I.H.

1987-01-01

The present study is aimed at commenting on the reactor-relevance of the design principles and technology being proposed for NET. The authors propose that a double-null device serve as a basis for a NET-based demonstration reactor. Calculations are carried out to determine the parameter set for reactors based on the double-null NET design, and the results are presented in tabular form. (U.K.)

Are eikonal quasinormal modes linked to the unstable circular null geodesics?

Directory of Open Access Journals (Sweden)

R.A. Konoplya

2017-08-01

Full Text Available In Cardoso et al. [6] it was claimed that quasinormal modes which any stationary, spherically symmetric and asymptotically flat black hole emits in the eikonal regime are determined by the parameters of the circular null geodesic: the real and imaginary parts of the quasinormal mode are multiples of the frequency and instability timescale of the circular null geodesics respectively. We shall consider asymptotically flat black hole in the Einstein–Lovelock theory, find analytical expressions for gravitational quasinormal modes in the eikonal regime and analyze the null geodesics. Comparison of the both phenomena shows that the expected link between the null geodesics and quasinormal modes is violated in the Einstein–Lovelock theory. Nevertheless, the correspondence exists for a number of other cases and here we formulate its actual limits.

Are eikonal quasinormal modes linked to the unstable circular null geodesics?

Science.gov (United States)

Konoplya, R. A.; Stuchlík, Z.

2017-08-01

In Cardoso et al. [6] it was claimed that quasinormal modes which any stationary, spherically symmetric and asymptotically flat black hole emits in the eikonal regime are determined by the parameters of the circular null geodesic: the real and imaginary parts of the quasinormal mode are multiples of the frequency and instability timescale of the circular null geodesics respectively. We shall consider asymptotically flat black hole in the Einstein-Lovelock theory, find analytical expressions for gravitational quasinormal modes in the eikonal regime and analyze the null geodesics. Comparison of the both phenomena shows that the expected link between the null geodesics and quasinormal modes is violated in the Einstein-Lovelock theory. Nevertheless, the correspondence exists for a number of other cases and here we formulate its actual limits.

Modular Hamiltonians on the null plane and the Markov property of the vacuum state

Science.gov (United States)

Casini, Horacio; Testé, Eduardo; Torroba, Gonzalo

2017-09-01

We compute the modular Hamiltonians of regions having the future horizon lying on a null plane. For a CFT this is equivalent to regions with a boundary of arbitrary shape lying on the null cone. These Hamiltonians have a local expression on the horizon formed by integrals of the stress tensor. We prove this result in two different ways, and show that the modular Hamiltonians of these regions form an infinite dimensional Lie algebra. The corresponding group of unitary transformations moves the fields on the null surface locally along the null generators with arbitrary null line dependent velocities, but act non-locally outside the null plane. We regain this result in greater generality using more abstract tools on the algebraic quantum field theory. Finally, we show that modular Hamiltonians on the null surface satisfy a Markov property that leads to the saturation of the strong sub-additive inequality for the entropies and to the strong super-additivity of the relative entropy.

sirt1-null mice develop an autoimmune-like condition

International Nuclear Information System (INIS)

Sequeira, Jedon; Boily, Gino; Bazinet, Stephanie; Saliba, Sarah; He Xiaohong; Jardine, Karen; Kennedy, Christopher; Staines, William; Rousseaux, Colin; Mueller, Rudi; McBurney, Michael W.

2008-01-01

The sirt1 gene encodes a protein deacetylase with a broad spectrum of reported substrates. Mice carrying null alleles for sirt1 are viable on outbred genetic backgrounds so we have examined them in detail to identify the biological processes that are dependent on SIRT1. Sera from adult sirt1-null mice contain antibodies that react with nuclear antigens and immune complexes become deposited in the livers and kidneys of these animals. Some of the sirt1-null animals develop a disease resembling diabetes insipidus when they approach 2 years of age although the relationship to the autoimmunity remains unclear. We interpret these observations as consistent with a role for SIRT1 in sustaining normal immune function and in this way delaying the onset of autoimmune disease

Single and multi-band electromagnetic induced transparency-like metamaterials with coupled split ring resonators

Science.gov (United States)

Bagci, Fulya; Akaoglu, Baris

2017-08-01

We present a metamaterial configuration exhibiting single and multi-band electromagnetic induced transparency (EIT)-like properties. The unit cell of the single band EIT-like metamaterial consists of a multi-split ring resonator surrounded by a split ring resonator. The multi-split ring resonator acts as a quasi-dark or dark resonator, depending on the polarization of the incident wave, and the split ring resonator serves as the bright resonator. Combination of these two resonators results in a single band EIT-like transmission inside the stop band. EIT-like transmission phenomenon is also clearly observed in the measured transmission spectrum at almost the same frequencies for vertical and horizontal polarized waves, and the numerical results are verified for normal incidence. Moreover, multi-band transmission windows are created within a wide band by combining the two slightly different single band EIT-like metamaterial unit cells that exhibit two different coupling strengths inside a supercell configuration. Group indices as high as 123 for single band and 488 for tri-band transmission, accompanying with high transmission rates (over 80%), are achieved, rendering the metamaterial very suitable for multi-band slow light applications. It is shown that the group delay of the propagating wave can be increased and dynamically controlled by changing the polarization angle. Multi-band EIT-like transmission is also verified experimentally, and a good agreement with simulations is obtained. The proposed novel methodology for obtaining multi-band EIT, which takes advantage of a supercell configuration by hosting slightly different configured unit cells, can be utilized for easily formation and manipulation of multi-band transmission windows inside a stop band.

A flexible WLAN receiver

NARCIS (Netherlands)

Schiphorst, Roelof; Hoeksema, F.W.; Slump, Cornelis H.

2003-01-01

Flexible radio receivers are also called Software Defined Radios (SDRs) [1], [2]. The focus of our SDR project [3] is on designing the front end, from antenna to demodulation in bits, of a °exible, multi-standard WLAN receiver. We try to combine an instance of a (G)FSK receiver (Bluetooth) with an

Fast and accurate inductance and coupling calculation for a multi-layer Nb process

International Nuclear Information System (INIS)

Fourie, Coenrad J; Takahashi, Akitomo; Yoshikawa, Nobuyuki

2015-01-01

Currently, fabrication processes for superconductive integrated circuits are moving to multiple wiring and shielding layers, some of which are placed below the main ground plane (GP) and device layers. The Advanced Industrial Science and Technology advanced process (ADP2) was the first such multi-layer Nb process with planarized passive transmission line and GP layers below the junction layer, and is at the time of writing still the most developed. This process allows complex circuit designs, and accurate inductance extraction helps to push the boundaries of the layouts possible. We show that the position of ground connections between ground layers influences the inductance of structures for which these GPs act as return path, and that this needs to be accounted for in modelling. However, due to the number of wiring layers and GPs, full layout modelling of large cells causes long calculation times. In this paper we discuss methods with which to reduce model size, and calibrate InductEx calculations using these methods against measured results. We show that model reduction followed by calibration results in fast calculation times while good accuracy is maintained. We also show that InductEx correctly handles coupling between conductors in a multi-layer layout, and how to model layouts to gauge unwanted coupling between power lines and single flux quantum electronics. (paper)

Analytically continued Fock space multi-reference coupled-cluster theory: Application to the shape resonance

International Nuclear Information System (INIS)

Pal, Sourav; Sajeev, Y.; Vaval, Nayana

2006-01-01

The Fock space multi-reference coupled-cluster (FSMRCC) method is used for the study of the shape resonance energy and width in an electron-atom/molecule collision. The procedure is based upon combining a complex absorbing potential (CAP) with FSMRCC theory. Accurate resonance parameters are obtained by solving a small non-Hermitian eigen-value problem. We study the shape resonances in e - -C 2 H 4 and e - -Mg

Null point of discrimination in crustacean polarisation vision.

Science.gov (United States)

How, Martin J; Christy, John; Roberts, Nicholas W; Marshall, N Justin

2014-07-15

The polarisation of light is used by many species of cephalopods and crustaceans to discriminate objects or to communicate. Most visual systems with this ability, such as that of the fiddler crab, include receptors with photopigments that are oriented horizontally and vertically relative to the outside world. Photoreceptors in such an orthogonal array are maximally sensitive to polarised light with the same fixed e-vector orientation. Using opponent neural connections, this two-channel system may produce a single value of polarisation contrast and, consequently, it may suffer from null points of discrimination. Stomatopod crustaceans use a different system for polarisation vision, comprising at least four types of polarisation-sensitive photoreceptor arranged at 0, 45, 90 and 135 deg relative to each other, in conjunction with extensive rotational eye movements. This anatomical arrangement should not suffer from equivalent null points of discrimination. To test whether these two systems were vulnerable to null points, we presented the fiddler crab Uca heteropleura and the stomatopod Haptosquilla trispinosa with polarised looming stimuli on a modified LCD monitor. The fiddler crab was less sensitive to differences in the degree of polarised light when the e-vector was at -45 deg than when the e-vector was horizontal. In comparison, stomatopods showed no difference in sensitivity between the two stimulus types. The results suggest that fiddler crabs suffer from a null point of sensitivity, while stomatopods do not. © 2014. Published by The Company of Biologists Ltd.

Logarithmic corrections to gravitational entropy and the null energy condition

Energy Technology Data Exchange (ETDEWEB)

Parikh, Maulik, E-mail: maulik.parikh@asu.edu; Svesko, Andrew

2016-10-10

Using a relation between the thermodynamics of local horizons and the null energy condition, we consider the effects of quantum corrections to the gravitational entropy. In particular, we find that the geometric form of the null energy condition is not affected by the inclusion of logarithmic corrections to the Bekenstein–Hawking entropy.

An efficient hydro-mechanical model for coupled multi-porosity and discrete fracture porous media

Science.gov (United States)

Yan, Xia; Huang, Zhaoqin; Yao, Jun; Li, Yang; Fan, Dongyan; Zhang, Kai

2018-02-01

In this paper, a numerical model is developed for coupled analysis of deforming fractured porous media with multiscale fractures. In this model, the macro-fractures are modeled explicitly by the embedded discrete fracture model, and the supporting effects of fluid and fillings in these fractures are represented explicitly in the geomechanics model. On the other hand, matrix and micro-fractures are modeled by a multi-porosity model, which aims to accurately describe the transient matrix-fracture fluid exchange process. A stabilized extended finite element method scheme is developed based on the polynomial pressure projection technique to address the displacement oscillation along macro-fracture boundaries. After that, the mixed space discretization and modified fixed stress sequential implicit methods based on non-matching grids are applied to solve the coupling model. Finally, we demonstrate the accuracy and application of the proposed method to capture the coupled hydro-mechanical impacts of multiscale fractures on fractured porous media.

Yang-Mills theory in null path space

International Nuclear Information System (INIS)

Kent, S.L.

1982-01-01

A reformulation of classical GL(n,c) Yang-Mills theory is presented. The reformulation is in terms of a single matrix-valued function G on a six-dimensional subspace of the space of paths in Minkowski space, M. This subspace is defined as the null paths beginning at each point, (X/sup a/), of M and ending at future null infinity. A convenient parametrization of these paths is to give the Minkowski coordinates x/sup a/ of the starting point and the (complex) stereographic coordinates (xi, antixi) on S 2 which label the light cone generators of x/sup a/. A path is thus labeled by (x/sup a/,xi, antixi). The function G(x/sup a/,xi, antixi) is defined by the parallel propagation (with a given connection) of n linearly independent fiber vectors from x/sup a/ to null infinity along the (xi, antixi) generator. From knowledge of G(x/sup a/,xi, antixi) the connection one-form γ/sub a/ at the point x/sup a/ can be obtained is shown. Furthermore how the vacuum Yang-Mills equations can be imposed on the G is shown. This results in a rather complicated integro-differential equation for G which involves the characteristic initial data (essentially the radiation field) acting as the driving term. Two simple special cases are immediately obtainable; in the case of self-dual (or anti-self dual) fields the author obtains a simple derivation of the Sparling equation, namely delta G = -GA, while for Abelian (Maxwell) theories obtained the equation delta anti delta log G = -anti delta A-anti delta A, where A and its conjugate anti A are the characteristic free data given on null infinity. The latter equation is equivalent to the vacuum Maxwell equations

Logarithmic corrections to gravitational entropy and the null energy condition

Directory of Open Access Journals (Sweden)

Maulik Parikh

2016-10-01

Full Text Available Using a relation between the thermodynamics of local horizons and the null energy condition, we consider the effects of quantum corrections to the gravitational entropy. In particular, we find that the geometric form of the null energy condition is not affected by the inclusion of logarithmic corrections to the Bekenstein–Hawking entropy.

Communications receivers principles and design

CERN Document Server

Rohde, Ulrich L; Zahnd, Hans

2017-01-01

This thoroughly updated guide offers comprehensive explanations of the science behind today’s radio receivers along with practical guidance on designing, constructing, and maintaining real-world communications systems. You will explore system planning, antennas and antenna coupling, amplifiers and gain control, filters, mixers, demodulation, digital communication, and the latest software defined radio (SDR) technology. Written by a team of telecommunication experts, Communications Receivers: Principles and Design, Fourth Edition, features technical illustrations, schematic diagrams, and detailed examples. Coverage includes: • Basic radio considerations • Radio receiver characteristics • Receiver system planning • Receiver implementation considerations • RF and baseband techniques for Software-Defined Radios • Transceiver SDR considerations • Antennas and antenna coupling • Mixers • Frequency sources and control • Ancillary receiver circuits • Performance measurement

Maxwell fields and shear-free null geodesic congruences

International Nuclear Information System (INIS)

Newman, Ezra T

2004-01-01

We study and report on the class of vacuum Maxwell fields in Minkowski space that possess a non-degenerate, diverging, principal null vector field (null eigenvector field of the Maxwell tensor) that is tangent to a shear-free null geodesics congruence. These congruences can be either surface forming (the tangent vectors being proportional to gradients) or not, i.e., the twisting congruences. In the non-twisting case, the associated Maxwell fields are precisely the Lienard-Wiechert fields, i.e., those Maxwell fields arising from an electric monopole moving on an arbitrary worldline. The null geodesic congruence is given by the generators of the light-cones with apex on the worldline. The twisting case is much richer, more interesting and far more complicated. In a twisting subcase, where our main interests lie, the following strange interpretation can be given. If we allow the real Minkowski space to be complexified so that the real Minkowski coordinates x a take complex values, i.e., x a → z a = x a + iy a with complex metric g η ab dz a dz b , the real vacuum Maxwell equations can be extended into the complex space and rewritten as curl W=i W radical, div W=0 with W=E+iB. This subcase of Maxwell fields can then be extended into the complex space so as to have as source, a complex analytic worldline, i.e., to now become complex Lienard-Wiechart fields. When viewed as real fields on the real Minkowski space (z a = x a ), they possess a real principal null vector that is shear-free but twisting and diverging. The twist is a measure of how far the complex worldline is from the real 'slice'. Most Maxwell fields in this subcase are asymptotically flat with a time-varying set of electric and magnetic moments, all depending on the complex displacements and the complex velocities

The data-driven null models for information dissemination tree in social networks

Science.gov (United States)

Zhang, Zhiwei; Wang, Zhenyu

2017-10-01

For the purpose of detecting relatedness and co-occurrence between users, as well as the distribution features of nodes in spreading path of a social network, this paper explores topological characteristics of information dissemination trees (IDT) that can be employed indirectly to probe the information dissemination laws within social networks. Hence, three different null models of IDT are presented in this article, including the statistical-constrained 0-order IDT null model, the random-rewire-broken-edge 0-order IDT null model and the random-rewire-broken-edge 2-order IDT null model. These null models firstly generate the corresponding randomized copy of an actual IDT; then the extended significance profile, which is developed by adding the cascade ratio of information dissemination path, is exploited not only to evaluate degree correlation of two nodes associated with an edge, but also to assess the cascade ratio of different length of information dissemination paths. The experimental correspondences of the empirical analysis for several SinaWeibo IDTs and Twitter IDTs indicate that the IDT null models presented in this paper perform well in terms of degree correlation of nodes and dissemination path cascade ratio, which can be better to reveal the features of information dissemination and to fit the situation of real social networks.

Experimental study of directionally solidified ferromagnetic shape memory alloy under multi-field coupling

Energy Technology Data Exchange (ETDEWEB)

Zhu, Yuping, E-mail: zhuyuping@126.com [Institute of Geophysics, China Earthquake Administration, Beijing 100081 (China); Chen, Tao; Teng, Yao [Faculty of Civil Engineering and Mechanics, Jiangsu University, Zhenjiang 212013 (China); Liu, Bingfei [Airport College, Civil Aviation University of China, Tianjin 300300 (China); Xue, Lijun [Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronical System, School of Mechanical Engineering, Tianjin University of Technology, Tianjin 300384 (China)

2016-11-01

Directionally solidified, polycrystalline Ni–Mn–Ga is studied in this paper. The polycrystalline Ni–Mn–Ga samples were cut at different angles to solidification direction. The magnetic field induced strain under constant stress and the temperature-induced strain under constant magnetic field during the loading–unloading cycle were measured. The experimental results show that the mechanical behavior during the loading–unloading cycle of the material is nonlinear and anisotropic. Based on the experimental results, the effects of multi-field coupling factors, such as stress, magnetic field, temperature and cutting angle on the mechanical behaviors were analyzed. Some useful conclusions were obtained, which will provide guidance for practical applications. - Highlights: • The magnetic-induced strains in different directions are tested. • The temperature-induced strains in different directions are tested. • The effects of coupling factors on directional solidification samples are studied.

Dynamic analysis of multiple nuclear-coupled boiling channels based on a multi-point reactor model

International Nuclear Information System (INIS)

Lee, J.D.; Pan Chin

2005-01-01

This work investigates the non-linear dynamics and stabilities of a multiple nuclear-coupled boiling channel system based on a multi-point reactor model using the Galerkin nodal approximation method. The nodal approximation method for the multiple boiling channels developed by Lee and Pan [Lee, J.D., Pan, C., 1999. Dynamics of multiple parallel boiling channel systems with forced flows. Nucl. Eng. Des. 192, 31-44] is extended to address the two-phase flow dynamics in the present study. The multi-point reactor model, modified from Uehiro et al. [Uehiro, M., Rao, Y.F., Fukuda, K., 1996. Linear stability analysis on instabilities of in-phase and out-of-phase modes in boiling water reactors. J. Nucl. Sci. Technol. 33, 628-635], is employed to study a multiple-channel system with unequal steady-state neutron density distribution. Stability maps, non-linear dynamics and effects of major parameters on the multiple nuclear-coupled boiling channel system subject to a constant total flow rate are examined. This study finds that the void-reactivity feedback and neutron interactions among subcores are coupled and their competing effects may influence the system stability under different operating conditions. For those cases with strong neutron interaction conditions, by strengthening the void-reactivity feedback, the nuclear-coupled effect on the non-linear dynamics may induce two unstable oscillation modes, the supercritical Hopf bifurcation and the subcritical Hopf bifurcation. Moreover, for those cases with weak neutron interactions, by quadrupling the void-reactivity feedback coefficient, period-doubling and complex chaotic oscillations may appear in a three-channel system under some specific operating conditions. A unique type of complex chaotic attractor may evolve from the Rossler attractor because of the coupled channel-to-channel thermal-hydraulic and subcore-to-subcore neutron interactions. Such a complex chaotic attractor has the imbedding dimension of 5 and the

Multi-phase induced inflation in theories with non-minimal coupling to gravity

Energy Technology Data Exchange (ETDEWEB)

Artymowski, Michał [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Lalak, Zygmunt; Lewicki, Marek, E-mail: Michal.Artymowski@uj.edu.pl, E-mail: Zygmunt.Lalak@fuw.edu.pl, E-mail: Marek.Lewicki@fuw.edu.pl [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw ul. Hoża 69, 00-681 Warszawa (Poland)

2017-01-01

In this paper we investigate the induced inflation with two flat regions: one Starobinsky-like plateau in strong coupling regime and one shorter plateau around the saddle point of the Einstein frame potential. This multi-phase inflationary scenario can be used to solve problems of classical cosmology as well as the problem of initial conditions for inflation. The inflation at the saddle-point plateau is consistent with the data and can have arbitrarily low scale. The results can be useful in the context of the Higgs-Axion relaxation and in a certain limit they are equivalent to the α-attractors.

Chaos and multi-scroll attractors in RCL-shunted junction coupled Jerk circuit connected by memristor

Science.gov (United States)

Zhou, Ping; Ahmad, Bashir; Ren, Guodong; Wang, Chunni

2018-01-01

In this paper, a new four-variable dynamical system is proposed to set chaotic circuit composed of memristor and Josephson junction, and the dependence of chaotic behaviors on nonlinearity is investigated. A magnetic flux-controlled memristor is used to couple with the RCL-shunted junction circuit, and the dynamical behaviors can be modulated by changing the coupling intensity between the memristor and the RCL-shunted junction. Bifurcation diagram and Lyapunov exponent are calculated to confirm the emergence of chaos in the improved dynamical system. The outputs and dynamical behaviors can be controlled by the initial setting and external stimulus as well. As a result, chaos can be suppressed and spiking occurs in the sampled outputs under negative feedback, while applying positive feedback type via memristor can be effective to trigger chaos. Furthermore, it is found that the number of multi-attractors in the Jerk circuit can be modulated when memristor coupling is applied on the circuit. These results indicate that memristor coupling can be effective to control chaotic circuits and it is also useful to reproduce dynamical behaviors for neuronal activities. PMID:29342178

Chaos and multi-scroll attractors in RCL-shunted junction coupled Jerk circuit connected by memristor.

Science.gov (United States)

Ma, Jun; Zhou, Ping; Ahmad, Bashir; Ren, Guodong; Wang, Chunni

2018-01-01

In this paper, a new four-variable dynamical system is proposed to set chaotic circuit composed of memristor and Josephson junction, and the dependence of chaotic behaviors on nonlinearity is investigated. A magnetic flux-controlled memristor is used to couple with the RCL-shunted junction circuit, and the dynamical behaviors can be modulated by changing the coupling intensity between the memristor and the RCL-shunted junction. Bifurcation diagram and Lyapunov exponent are calculated to confirm the emergence of chaos in the improved dynamical system. The outputs and dynamical behaviors can be controlled by the initial setting and external stimulus as well. As a result, chaos can be suppressed and spiking occurs in the sampled outputs under negative feedback, while applying positive feedback type via memristor can be effective to trigger chaos. Furthermore, it is found that the number of multi-attractors in the Jerk circuit can be modulated when memristor coupling is applied on the circuit. These results indicate that memristor coupling can be effective to control chaotic circuits and it is also useful to reproduce dynamical behaviors for neuronal activities.

On the geometry of null congruences in general relativity

International Nuclear Information System (INIS)

Ahsan, Zafar; Malik, N.P.

1977-01-01

Some theorems for the null congruences within the framework of general theory of relativity are given. These theorems are important in themselves as they illustrate the geometric meaning of the spin coefficients. The newly developed Geroch-Held-Penrose (GHP) formalism has been used throughout the investigations. The salient features of GHP formalism that are necessary for the present work are given and these techniques are applied to a pair of null congruences C(l) and C(n). (author)

pyNSMC: A Python Module for Null-Space Monte Carlo Uncertainty Analysis

Science.gov (United States)

White, J.; Brakefield, L. K.

2015-12-01

The null-space monte carlo technique is a non-linear uncertainty analyses technique that is well-suited to high-dimensional inverse problems. While the technique is powerful, the existing workflow for completing null-space monte carlo is cumbersome, requiring the use of multiple commandline utilities, several sets of intermediate files and even a text editor. pyNSMC is an open-source python module that automates the workflow of null-space monte carlo uncertainty analyses. The module is fully compatible with the PEST and PEST++ software suites and leverages existing functionality of pyEMU, a python framework for linear-based uncertainty analyses. pyNSMC greatly simplifies the existing workflow for null-space monte carlo by taking advantage of object oriented design facilities in python. The core of pyNSMC is the ensemble class, which draws and stores realized random vectors and also provides functionality for exporting and visualizing results. By relieving users of the tedium associated with file handling and command line utility execution, pyNSMC instead focuses the user on the important steps and assumptions of null-space monte carlo analysis. Furthermore, pyNSMC facilitates learning through flow charts and results visualization, which are available at many points in the algorithm. The ease-of-use of the pyNSMC workflow is compared to the existing workflow for null-space monte carlo for a synthetic groundwater model with hundreds of estimable parameters.

Reproducible Analysis and Blindness in a Null Test of Newton's Gravitational Inverse Square Law At Sub-millimeter Scales

Science.gov (United States)

Hagedorn, Charles; Venkateswara, Krishna; Gundlach, Jens

2016-03-01

Proper execution of an experiment is independent of its result. Physicists who test fundamental physical law face the reality that signals for new physics receive more attention and scrutiny than null results. Yet, null results may have greater impact upon the direction of both experiment and theory. Blind experiments and result-blind review are bulwarks against systematic human bias for both experimenters and referees. I'll describe the method that made possible an irreversible public unblinding of our torsion-balance parallel-plate test of gravity at submillimeter scales in 2015. One publicly-available computer procedure generated from blind raw data the analysis, the final result, and the complete documenting thesis. The experiment included an optical ``foil monitor'' to constrain a systematic effect intrinsic to all short-range parallel-plate gravity experiments. I'll describe the experiment, successes, lessons learned, and result. Supported by NSF (PHY-1305726) and DOE support for CENPA.

Testing the null hypothesis: the forgotten legacy of Karl Popper?

Science.gov (United States)

Wilkinson, Mick

2013-01-01

Testing of the null hypothesis is a fundamental aspect of the scientific method and has its basis in the falsification theory of Karl Popper. Null hypothesis testing makes use of deductive reasoning to ensure that the truth of conclusions is irrefutable. In contrast, attempting to demonstrate the new facts on the basis of testing the experimental or research hypothesis makes use of inductive reasoning and is prone to the problem of the Uniformity of Nature assumption described by David Hume in the eighteenth century. Despite this issue and the well documented solution provided by Popper's falsification theory, the majority of publications are still written such that they suggest the research hypothesis is being tested. This is contrary to accepted scientific convention and possibly highlights a poor understanding of the application of conventional significance-based data analysis approaches. Our work should remain driven by conjecture and attempted falsification such that it is always the null hypothesis that is tested. The write up of our studies should make it clear that we are indeed testing the null hypothesis and conforming to the established and accepted philosophical conventions of the scientific method.

Application of the coupled code Athlet-Quabox/Cubbox for the extreme scenarios of the OECD/NRC BWR turbine trip benchmark and its performance on multi-processor computers

International Nuclear Information System (INIS)

Langenbuch, S.; Schmidt, K.D.; Velkov, K.

2003-01-01

The OECD/NRC BWR Turbine Trip (TT) Benchmark is investigated to perform code-to-code comparison of coupled codes including a comparison to measured data which are available from turbine trip experiments at Peach Bottom 2. This Benchmark problem for a BWR over-pressure transient represents a challenging application of coupled codes which integrate 3-dimensional neutron kinetics into thermal-hydraulic system codes for best-estimate simulation of plant transients. This transient represents a typical application of coupled codes which are usually performed on powerful workstations using a single CPU. Nowadays, the availability of multi-CPUs is much easier. Indeed, powerful workstations already provide 4 to 8 CPU, computer centers give access to multi-processor systems with numbers of CPUs in the order of 16 up to several 100. Therefore, the performance of the coupled code Athlet-Quabox/Cubbox on multi-processor systems is studied. Different cases of application lead to changing requirements of the code efficiency, because the amount of computer time spent in different parts of the code is varying. This paper presents main results of the coupled code Athlet-Quabox/Cubbox for the extreme scenarios of the BWR TT Benchmark together with evaluations of the code performance on multi-processor computers. (authors)

Null controllability of a cascade system of Schrodinger equations

Directory of Open Access Journals (Sweden)

Marcos Lopez-Garcia

2016-03-01

Full Text Available This article presents a control problem for a cascade system of two linear N-dimensional Schrodinger equations. We address the problem of null controllability by means of a control supported in a region not satisfying the classical geometrical control condition. The proof is based on the application of a Carleman estimate with degenerate weights to each one of the equations and a careful analysis of the system in order to prove null controllability with only one control force.

Fast digitization and digital receiver technology

International Nuclear Information System (INIS)

Kimball, Ralph C.

2002-01-01

The potentially lucrative wireless market has led to technological advances in mixed signal devices such as high speed, high resolution A/D and D/A converters. This same market has also driven the development of high performance multi-channel digital receiver and digital transmitter ICs. Similarly, advances in semiconductor processes, coupled with the need for reduced time-to-market, has led to the development of large, enhanced performance, in-circuit programmable logic devices. A review of the key characteristics of these mixed-signal, signal processing and programmable logic devices is presented. The application of these devices and technologies to the instrumentation of Accelerators and Storage Rings is discussed and presented by way of examples. Issues relating to the requirements associated with real-time processing, I/O throughput, reconfigurability, reliability, maintainability and packaging requirements are also addressed

A multi-platform investigation of midlatitude sporadic E and its ties to E–F coupling and meteor activity

Directory of Open Access Journals (Sweden)

J. Helmboldt

2016-05-01

Full Text Available This paper describes the results of a multi-platform observing campaign aimed at studying midlatitude sporadic E (Es and associated ionospheric phenomena. The assets used were the digisonde in Boulder, Colorado; the first station of the Long Wavelength Array, LWA1, in New Mexico; the transmitters of the radio station WWV in Colorado; and 61 continuously operating GPS receivers between LWA1 and WWV. The results show that southwestward-directed medium-scale traveling ionospheric disturbances (MSTIDs were substantially more prevalent when Es was detected. The amplitudes of these correlate with a plasma frequency up to about 4.5 MHz. For fp ≳ 5 MHz, the MSTIDs become significantly weaker and basically vanish above  ∼ 6.5 MHz. The prevalence of meteor trail reflections observed with LWA1 also correlates with fp up to about 4.5 MHz; above this limit, the relationship exhibits a significant turnover. The observed intensity of coherent backscatter from Es field-aligned irregularities (FAIs also correlates with inferred plasma frequency. However, this trend continues to higher frequencies with a peak near 6 MHz, followed by a much more subtle turnover. The reflected power from Es structures observed with LWA1 is significantly more correlated on spatial scales between 10 and 40 km. The magnitude of this correlation increases with fp up to  ∼  6 MHz, above which it drops. These results are consistent with the following: (1 southwestward-directed MSTIDs are produced via E–F coupling; (2 this coupling is stronger when the Es layer, seeded by meteor ablation, is more dense; (3 the coupling is substantially diminished for Es layers harboring extremely dense structures (fp ≳ 5 MHz.

THE NATURE OF FLARE RIBBONS IN CORONAL NULL-POINT TOPOLOGY

International Nuclear Information System (INIS)

Masson, S.; Aulanier, G.; Pariat, E.; Schrijver, C. J.

2009-01-01

Flare ribbons are commonly attributed to the low-altitude impact, along the footprints of separatrices or quasi-separatrix layers (QSLs), of particle beams accelerated through magnetic reconnection. If reconnection occurs at a three-dimensional coronal magnetic null point, the footprint of the dome-shaped fan surface would map a closed circular ribbon. This paper addresses the following issues: does the entire circular ribbon brighten simultaneously, as expected because all fan field lines pass through the null point? And since the spine separatrices are singular field lines, do spine-related ribbons look like compact kernels? What can we learn from these observations about current sheet formation and magnetic reconnection in a null-point topology? The present study addresses these questions by analyzing Transition Region and Coronal Explorer and Solar and Heliospheric Observatory/Michelson Doppler Imager observations of a confined flare presenting a circular ribbon. Using a potential field extrapolation, we linked the circular shape of the ribbon with the photospheric mapping of the fan field lines originating from a coronal null point. Observations show that the flare ribbon outlining the fan lines brightens sequentially along the counterclockwise direction and that the spine-related ribbons are elongated. Using the potential field extrapolation as initial condition, we conduct a low-β resistive magnetohydrodynamics simulation of this observed event. We drive the coronal evolution by line-tied diverging boundary motions, so as to emulate the observed photospheric flow pattern associated with some magnetic flux emergence. The numerical analysis allows us to explain several observed features of the confined flare. The vorticity induced in the fan by the prescribed motions causes the spines to tear apart along the fan. This leads to formation of a thin current sheet and induces null-point reconnection. We also find that the null point and its associated topological

The (2, 0) superalgebra, null M-branes and Hitchin's system

Science.gov (United States)

Kucharski, P.; Lambert, N.; Owen, M.

2017-10-01

We present an interacting system of equations with sixteen supersymmetries and an SO(2) × SO(6) R-symmetry where the fields depend on two space and one null dimensions that is derived from a representation of the six-dimensional (2, 0) superalgebra. The system can be viewed as two M5-branes compactified on {S}-^1× T^2 or equivalently as M2-branes on R+× R^2 , where ± refer to null directions. We show that for a particular choice of fields the dynamics can be reduced to motion on the moduli space of solutions to the Hitchin system. We argue that this provides a description of intersecting null M2-branes and is also related by U-duality to a DLCQ description of four-dimensional maximally supersymmetric Yang-Mills.

Vacuum Nuller Testbed (VNT) Performance, Characterization and Null Control: Progress Report

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.; Noecker, M. Charley; Kendrick, Stephen; Helmbrecht, Michael

2011-01-01

Herein we report on the development. sensing and control and our first results with the Vacuum Nuller Testbed to realize a Visible Nulling Coronagraph (VNC) for exoplanet coronagraphy. The VNC is one of the few approaches that works with filled. segmented and sparse or diluted-aperture telescope systems. It thus spans a range of potential future NASA telescopes and could be Hown as a separate instrument on such a future mission. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies. and has developed an incremental sequence of VNC testbeds to advance this approach and the enabling technologies associated with it. We discuss the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). Tbe VNT is an ultra-stable vibration isolated testbed that operates under closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible-light nulling milestones with sequentially higher contrasts of 10(sup 8), 10(sup 9) and ideally 10(sup 10) at an inner working angle of 2*lambda/D. The VNT is based on a modified Mach-Zehnder nulling interferometer, with a "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We discuss the initial laboratory results, the optical configuration, critical technologies and the null sensing and control approach.

Vacuum nuller testbed (VNT) performance, characterization and null control: progress report

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.; Noecker, M. Charley; Kendrick, Stephen; Helmbrecht, Michael

2011-10-01

Herein we report on the development, sensing and control and our first results with the Vacuum Nuller Testbed to realize a Visible Nulling Coronagraph (VNC) for exoplanet coronagraphy. The VNC is one of the few approaches that works with filled, segmented and sparse or diluted-aperture telescope systems. It thus spans a range of potential future NASA telescopes and could be flown as a separate instrument on such a future mission. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop VNC technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and the enabling technologies associated with it. We discuss the continued development of the vacuum Visible Nulling Coronagraph testbed (VNT). The VNT is an ultra-stable vibration isolated testbed that operates under closed-loop control within a vacuum chamber. It will be used to achieve an incremental sequence of three visible-light nulling milestones with sequentially higher contrasts of 108, 109, and ideally 1010 at an inner working angle of 2*λ/D. The VNT is based on a modified Mach-Zehnder nulling interferometer, with a "W" configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We discuss the initial laboratory results, the optical configuration, critical technologies and the null sensing and control approach.

Nulling tomography with weak gravitational lensing

International Nuclear Information System (INIS)

Huterer, Dragan; White, Martin

2005-01-01

We explore several strategies of eliminating (or nulling) the small-scale information in weak lensing convergence power spectrum measurements in order to protect against undesirable effects, for example, the effects of baryonic cooling and pressure forces on the distribution of large-scale structures. We selectively throw out the small-scale information in the convergence power spectrum that is most sensitive to the unwanted bias, while trying to retain most of the sensitivity to cosmological parameters. The strategies are effective in the difficult but realistic situations when we are able to guess the form of the contaminating effect only approximately. However, we also find that the simplest scheme of simply not using information from the largest multipoles works about as well as the proposed techniques in most, although not all, realistic cases. We advocate further exploration of nulling techniques and believe that they will find important applications in the weak lensing data mining

Lovelock vacua with a recurrent null vector field

Science.gov (United States)

Ortaggio, Marcello

2018-02-01

Vacuum solutions of Lovelock gravity in the presence of a recurrent null vector field (a subset of Kundt spacetimes) are studied. We first discuss the general field equations, which constrain both the base space and the profile functions. While choosing a "generic" base space puts stronger constraints on the profile, in special cases there also exist solutions containing arbitrary functions (at least for certain values of the coupling constants). These and other properties (such as the p p - waves subclass and the overlap with VSI, CSI and universal spacetimes) are subsequently analyzed in more detail in lower dimensions n =5 , 6 as well as for particular choices of the base manifold. The obtained solutions describe various classes of nonexpanding gravitational waves propagating, e.g., in Nariai-like backgrounds M2×Σn -2. An Appendix contains some results about general (i.e., not necessarily Kundt) Lovelock vacua of Riemann type III/N and of Weyl and traceless-Ricci type III/N. For example, it is pointed out that for theories admitting a triply degenerate maximally symmetric vacuum, all the (reduced) field equations are satisfied identically, giving rise to large classes of exact solutions.

An improved null model for assessing the net effects of multiple stressors on communities.

Science.gov (United States)

Thompson, Patrick L; MacLennan, Megan M; Vinebrooke, Rolf D

2018-01-01

Ecological stressors (i.e., environmental factors outside their normal range of variation) can mediate each other through their interactions, leading to unexpected combined effects on communities. Determining whether the net effect of stressors is ecologically surprising requires comparing their cumulative impact to a null model that represents the linear combination of their individual effects (i.e., an additive expectation). However, we show that standard additive and multiplicative null models that base their predictions on the effects of single stressors on community properties (e.g., species richness or biomass) do not provide this linear expectation, leading to incorrect interpretations of antagonistic and synergistic responses by communities. We present an alternative, the compositional null model, which instead bases its predictions on the effects of stressors on individual species, and then aggregates them to the community level. Simulations demonstrate the improved ability of the compositional null model to accurately provide a linear expectation of the net effect of stressors. We simulate the response of communities to paired stressors that affect species in a purely additive fashion and compare the relative abilities of the compositional null model and two standard community property null models (additive and multiplicative) to predict these linear changes in species richness and community biomass across different combinations (both positive, negative, or opposite) and intensities of stressors. The compositional model predicts the linear effects of multiple stressors under almost all scenarios, allowing for proper classification of net effects, whereas the standard null models do not. Our findings suggest that current estimates of the prevalence of ecological surprises on communities based on community property null models are unreliable, and should be improved by integrating the responses of individual species to the community level as does our

Multi-chord fiber-coupled interferometry of supersonic plasma jets (invited)

International Nuclear Information System (INIS)

Merritt, Elizabeth C.; Lynn, Alan G.; Gilmore, Mark A.; Thoma, Carsten; Loverich, John; Hsu, Scott C.

2012-01-01

A multi-chord fiber-coupled interferometer is being used to make time-resolved density measurements of supersonic argon plasma jets on the Plasma Liner Experiment. The long coherence length of the laser (>10 m) allows signal and reference path lengths to be mismatched by many meters without signal degradation, making for a greatly simplified optical layout. Measured interferometry phase shifts are consistent with a partially ionized plasma in which both positive and negative phase shift values are observed depending on the ionization fraction. In this case, both free electrons and bound electrons in ions and neutral atoms contribute to the index of refraction. This paper illustrates how the interferometry data, aided by numerical modeling, are used to derive total jet density, jet propagation velocity (∼15–50 km/s), jet length (∼20–100 cm), and 3D expansion.

The supersymmetric configurations of N=2, d=4 supergravity coupled to vector supermultiplets

CERN Document Server

Meessen, P

2006-01-01

We classify all the supersymmetric configurations of ungauged N=2,d=4 supergravity coupled to n vector multiplets and determine under which conditions they are also classical solutions of the equations of motion. The supersymmetric configurations fall into two classes, depending on the timelike or null nature of the Killing vector constructed from Killing spinor bilinears. The timelike class configurations are essentially the ones found by Behrndt, Luest and Sabra, which exhaust this class and are the ones that include supersymmetric black holes. The null class configurations include pp-waves and cosmic strings.

Visible Nulling Coronagraphy for Exo-Planetary Detection and Characterization

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Woodruff, Robert; Vasudevan, Gopal; Shao, Mike; Levine, Martin; Melnick, Gary; Tolls, Volker; Petrone, Peter; Dogoda, Peter; Duval, Julia; Ge, Jian

Visible Nulling Coronagraphy (VNC) is the proposed method of detecting and characterizing exo-solar Jovian planets (null depth 10-9) for the proposed NASA's Extrasolar Planetary Imaging Coronagraph (EPIC) Clampin & Lyon 2004 and is an approach under evaluation for NASA's Terrestrial Planet Finder (TPF) mission. The VNC approach uses a single unobscured filled-aperture telescope and splits, via a 50:50 beamsplitter, its re-imaged pupil into two paths within a Mach-Zender interferometer. An achromatic PI phase shift is imposed onto one beam path and the two paths are laterally sheared with respect to each other. The two beams are recombined at a second 50:50 beamsplitter. The net effect is that the on axis (stellar) light is transmitted out of the bright interferometer arm while the off-axis (planetary) light is transmitted out of the nulled interferometer arm. The bright output is used for fine pointing control and coarse wavefront control. The nulled output is relayed to the science camera for science imagery and fine wavefront control. The actual transmission pattern, projected on the sky, follows a θ^2 pattern for a single shear, θ^4 for a double shear, with the spacing of the successive maxima proportional to the inverse of the relative lateral shear. Combinations of shears and spacecraft rolls build up the spatial frequency content of the sky transmission pattern in the same manner as imaging interferometer builds up the spatial frequency content of the image.

Self-Nulling Beam Combiner Using No External Phase Inverter

Science.gov (United States)

Bloemhof, Eric E.

2010-01-01

A self-nulling beam combiner is proposed that completely eliminates the phase inversion subsystem from the nulling interferometer, and instead uses the intrinsic phase shifts in the beam splitters. Simplifying the flight instrument in this way will be a valuable enhancement of mission reliability. The tighter tolerances on R = T (R being reflection and T being transmission coefficients) required by the self-nulling configuration actually impose no new constraints on the architecture, as two adaptive nullers must be situated between beam splitters to correct small errors in the coatings. The new feature is exploiting the natural phase shifts in beam combiners to achieve the 180 phase inversion necessary for nulling. The advantage over prior art is that an entire subsystem, the field-flipping optics, can be eliminated. For ultimate simplicity in the flight instrument, one might fabricate coatings to very high tolerances and dispense with the adaptive nullers altogether, with all their moving parts, along with the field flipper subsystem. A single adaptive nuller upstream of the beam combiner may be required to correct beam train errors (systematic noise), but in some circumstances phase chopping reduces these errors substantially, and there may be ways to further reduce the chop residuals. Though such coatings are beyond the current state of the art, the mechanical simplicity and robustness of a flight system without field flipper or adaptive nullers would perhaps justify considerable effort on coating fabrication.

Null cone superspace supergravity

International Nuclear Information System (INIS)

Downes-Martin, S.G.

1980-03-01

The null cone formalism is used to derive a 2(N-1) parameter family of constraints for O(N) extended superspace supergravity. The invariance groups of these constraints is analysed and is found to be [subgroup U submanifold] contains GL(4,R) for N = 1, the submanifold being eliminated for N > 1. The invariance group defines non-Weyl rotations on the superbein which combine to form Weyl transformations on the supertangent space metric. The invariance of the supergravity Lagrangian under these transformations is discussed. (Auth.)

High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

2012-01-01

Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal planeregion extending from 14 D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. TheVNC is a hybrid interferometriccoronagraphic approach for exoplanet science. It operates with high Lyot stopefficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential futureNASA flight telescopes. NASAGoddard Space Flight Center (GSFC) has a well-established effort to develop the VNCand its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and itsenabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry tounprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a W configurationto accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters.We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, criticaltechnologies and null sensing and control.

High contrast vacuum nuller testbed (VNT) contrast, performance, and null control

Science.gov (United States)

Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Mallik, Udayan; Madison, Timothy; Bolcar, Matthew R.

2012-09-01

Herein we report on our Visible Nulling Coronagraph high-contrast result of 109 contrast averaged over a focal plane region extending from 1 - 4 λ/D with the Vacuum Nuller Testbed (VNT) in a vibration isolated vacuum chamber. The VNC is a hybrid interferometric/coronagraphic approach for exoplanet science. It operates with high Lyot stop efficiency for filled, segmented and sparse or diluted-aperture telescopes, thereby spanning the range of potential future NASA flight telescopes. NASA/Goddard Space Flight Center (GSFC) has a well-established effort to develop the VNC and its technologies, and has developed an incremental sequence of VNC testbeds to advance this approach and its enabling technologies. These testbeds have enabled advancement of high-contrast, visible light, nulling interferometry to unprecedented levels. The VNC is based on a modified Mach-Zehnder nulling interferometer, with a “W” configuration to accommodate a hex-packed MEMS based deformable mirror, a coherent fiber bundle and achromatic phase shifters. We give an overview of the VNT and discuss the high-contrast laboratory results, the optical configuration, critical technologies and null sensing and control.

Fano resonances in a high-Q terahertz whispering-gallery mode resonator coupled to a multi-mode waveguide.

Science.gov (United States)

Vogt, Dominik Walter; Leonhardt, Rainer

2017-11-01

We report on Fano resonances in a high-quality (Q) whispering-gallery mode (WGM) spherical resonator coupled to a multi-mode waveguide in the terahertz (THz) frequency range. The asymmetric line shape and phase of the Fano resonances detected with coherent continuous-wave (CW) THz spectroscopy measurements are in excellent agreement with the analytical model. A very high Q factor of 1600, and a finesse of 22 at critical coupling is observed around 0.35 THz. To the best of our knowledge this is the highest Q factor ever reported for a THz WGM resonator.

Spatial and null infinity via advanced and retarded conformal factors

International Nuclear Information System (INIS)

Hayward, Sean A.

2003-01-01

A new approach to space-time asymptotics is presented, refining Penrose's idea of conformal transformations with infinity represented by the conformal boundary of space-time. It is proposed that the Penrose conformal factor be a product of advanced and retarded conformal factors, which asymptotically relate physical and conformal null coordinates and vanish at future and past null infinity respectively. A refined definition of asymptotic flatness at both spatial and null infinity is given, including that the conformal boundary is locally a light cone, with spatial infinity as the vertex. It is shown how to choose the conformal factors so that this asymptotic light cone is locally a metric light cone. The theory is implemented in the spin-coefficient (or null-tetrad) formalism by a joint transformation of the spin-metric and spin-basis (or metric and tetrad). Asymptotic regularity conditions are proposed, based on the conformal boundary locally being a smoothly embedded metric light cone. These conditions ensure that the Bondi-Sachs energy-flux integrals of ingoing and outgoing gravitational radiation decay at spatial infinity such that the total radiated energy is finite, and that the Bondi-Sachs energy-momentum has a unique limit at spatial infinity, coinciding with the uniquely rendered ADM energy-momentum

Unicorns do exist: a tutorial on "proving" the null hypothesis.

Science.gov (United States)

Streiner, David L

2003-12-01

Introductory statistics classes teach us that we can never prove the null hypothesis; all we can do is reject or fail to reject it. However, there are times when it is necessary to try to prove the nonexistence of a difference between groups. This most often happens within the context of comparing a new treatment against an established one and showing that the new intervention is not inferior to the standard. This article first outlines the logic of "noninferiority" testing by differentiating between the null hypothesis (that which we are trying to nullify) and the "nill" hypothesis (there is no difference), reversing the role of the null and alternate hypotheses, and defining an interval within which groups are said to be equivalent. We then work through an example and show how to calculate sample sizes for noninferiority studies.

Chaos and multi-scroll attractors in RCL-shunted junction coupled Jerk circuit connected by memristor.

Directory of Open Access Journals (Sweden)

Jun Ma

Full Text Available In this paper, a new four-variable dynamical system is proposed to set chaotic circuit composed of memristor and Josephson junction, and the dependence of chaotic behaviors on nonlinearity is investigated. A magnetic flux-controlled memristor is used to couple with the RCL-shunted junction circuit, and the dynamical behaviors can be modulated by changing the coupling intensity between the memristor and the RCL-shunted junction. Bifurcation diagram and Lyapunov exponent are calculated to confirm the emergence of chaos in the improved dynamical system. The outputs and dynamical behaviors can be controlled by the initial setting and external stimulus as well. As a result, chaos can be suppressed and spiking occurs in the sampled outputs under negative feedback, while applying positive feedback type via memristor can be effective to trigger chaos. Furthermore, it is found that the number of multi-attractors in the Jerk circuit can be modulated when memristor coupling is applied on the circuit. These results indicate that memristor coupling can be effective to control chaotic circuits and it is also useful to reproduce dynamical behaviors for neuronal activities.

Causal null hypotheses of sustained treatment strategies: What can be tested with an instrumental variable?

Science.gov (United States)

Swanson, Sonja A; Labrecque, Jeremy; Hernán, Miguel A

2018-05-02

Sometimes instrumental variable methods are used to test whether a causal effect is null rather than to estimate the magnitude of a causal effect. However, when instrumental variable methods are applied to time-varying exposures, as in many Mendelian randomization studies, it is unclear what causal null hypothesis is tested. Here, we consider different versions of causal null hypotheses for time-varying exposures, show that the instrumental variable conditions alone are insufficient to test some of them, and describe additional assumptions that can be made to test a wider range of causal null hypotheses, including both sharp and average causal null hypotheses. Implications for interpretation and reporting of instrumental variable results are discussed.

Measurement of high-departure aspheres using subaperture stitching with the Variable Optical Null (VON)

Science.gov (United States)

Kulawiec, Andrew; Murphy, Paul; DeMarco, Michael

2010-10-01

Aspheric surfaces are proven to provide significant benefits to a wide variety of optical systems, but the ability to produce high-precision aspheric surfaces has historically been limited by the ability (or lack thereof) to measure them. Traditionally, aspheric measurements have required dedicated null optics, but the cost, lead time, and calibration difficulty of using null optics has made the use of aspheres more challenging and less attractive. In the past three years, QED has developed the Subaperture Stitching Interferometer for Aspheres (SSI-A®) to help address this limitation, providing flexible aspheric measurement capability of up to 200 waves of aspheric departure from best-fit sphere. Some aspheres, however, have thousands of waves of departure. We have recently developed Variable Optical Null (VON) technology that can null much of the aspheric departure in a subaperture. The VON is automatically configurable and is adjusted to nearly null each specific subaperture of an asphere. This ability to nearly null a local subaperture of an asphere provides a significant boost in aspheric measurement capability, enabling aspheres with up to 1000 waves of departure to be measured, without the use of dedicated null optics. We outline the basic principles of subaperture stitching and VON technology, demonstrate the extended capability provided by the VON, and present measurement results from the new Aspheric Stitching Interferometer (ASI®).

Broadband Active Segmented Aperture and Radial Shear Nulling

Data.gov (United States)

National Aeronautics and Space Administration — The Visible Nulling Coronagraph (VNC) is a starlight suppression system for enabling exoplanet detectionand atmospheric measurement. Conceptual space telescope...

Null canonical formalism 1, Maxwell field. [Poisson brackets, boundary conditions

Energy Technology Data Exchange (ETDEWEB)

Wodkiewicz, K [Warsaw Univ. (Poland). Inst. Fizyki Teoretycznej

1975-01-01

The purpose of this paper is to formulate the canonical formalism on null hypersurfaces for the Maxwell electrodynamics. The set of the Poisson brackets relations for null variables of the Maxwell field is obtained. The asymptotic properties of the theory are investigated. The Poisson bracket relations for the news-functions of the Maxwell field are computed. The Hamiltonian form of the asymptotic Maxwell equations in terms of these news-functions is obtained.

Null polygonal Wilson loops and minimal surfaces in Anti-de-Sitter space

International Nuclear Information System (INIS)

Alday, Luis F.; Maldacena, Juan

2009-01-01

We consider minimal surfaces in three dimensional anti-de-Sitter space that end at the AdS boundary on a polygon given by a sequence of null segments. The problem can be reduced to a certain generalized Sinh-Gordon equation and to SU(2) Hitchin equations. We describe in detail the mathematical problem that needs to be solved. This problem is mathematically the same as the one studied by Gaiotto, Moore and Neitzke in the context of the moduli space of certain supersymmetric theories. Using their results we can find the explicit answer for the area of a surface that ends on an eight-sided polygon. Via the gauge/gravity duality this can also be interpreted as a certain eight-gluon scattering amplitude at strong coupling. In addition, we give fairly explicit solutions for regular polygons.

Spherical null geodesics of rotating Kerr black holes

International Nuclear Information System (INIS)

Hod, Shahar

2013-01-01

The non-equatorial spherical null geodesics of rotating Kerr black holes are studied analytically. Unlike the extensively studied equatorial circular orbits whose radii are known analytically, no closed-form formula exists in the literature for the radii of generic (non-equatorial) spherical geodesics. We provide here an approximate formula for the radii r ph (a/M;cosi) of these spherical null geodesics, where a/M is the dimensionless angular momentum of the black hole and cos i is an effective inclination angle (with respect to the black-hole equatorial plane) of the orbit. It is well-known that the equatorial circular geodesics of the Kerr spacetime (the prograde and the retrograde orbits with cosi=±1) are characterized by a monotonic dependence of their radii r ph (a/M;cosi=±1) on the dimensionless spin-parameter a/M of the black hole. We use here our novel analytical formula to reveal that this well-known property of the equatorial circular geodesics is actually not a generic property of the Kerr spacetime. In particular, we find that counter-rotating spherical null orbits in the range (3√(3)−√(59))/4≲cosi ph (a/M;cosi=const) on the dimensionless rotation-parameter a/M of the black hole. Furthermore, it is shown that spherical photon orbits of rapidly-rotating black holes are characterized by a critical inclination angle, cosi=√(4/7), above which the coordinate radii of the orbits approach the black-hole radius in the extremal limit. We prove that this critical inclination angle signals a transition in the physical properties of the spherical null geodesics: in particular, it separates orbits which are characterized by finite proper distances to the black-hole horizon from orbits which are characterized by infinite proper distances to the horizon.

A Null Space Control of Two Wheels Driven Mobile Manipulator Using Passivity Theory

Science.gov (United States)

Shibata, Tsuyoshi; Murakami, Toshiyuki

This paper describes a control strategy of null space motion of a two wheels driven mobile manipulator. Recently, robot is utilized in various industrial fields and it is preferable for the robot manipulator to have multiple degrees of freedom motion. Several studies of kinematics for null space motion have been proposed. However stability analysis of null space motion is not enough. Furthermore, these approaches apply to stable systems, but they do not apply unstable systems. Then, in this research, base of manipulator equips with two wheels driven mobile robot. This robot is called two wheels driven mobile manipulator, which becomes unstable system. In the proposed approach, a control design of null space uses passivity based stabilizing. A proposed controller is decided so that closed-loop system of robot dynamics satisfies passivity. This is passivity based control. Then, control strategy is that stabilizing of the robot system applies to work space observer based approach and null space control while keeping end-effector position. The validity of the proposed approach is verified by simulations and experiments of two wheels driven mobile manipulator.

Standard and Null Weak Values

OpenAIRE

Zilberberg, Oded; Romito, Alessandro; Gefen, Yuval

2013-01-01

Weak value (WV) is a quantum mechanical measurement protocol, proposed by Aharonov, Albert, and Vaidman. It consists of a weak measurement, which is weighed in, conditional on the outcome of a later, strong measurement. Here we define another two-step measurement protocol, null weak value (NVW), and point out its advantages as compared to WV. We present two alternative derivations of NWVs and compare them to the corresponding derivations of WVs.

Anti-optic-null medium: Achieving the optic-null medium effect by enclosing an air region with relatively low-anisotropy media

Science.gov (United States)

Sun, Fei; Liu, Yichao; He, Sailing

2016-07-01

A so-called anti-optic-null medium (anti-ONM), which can be utilized to cancel the optic-null medium (ONM) and create many novel optical illusions, is introduced and designed by transformation optics (TO). Optical separation illusions can be achieved with an anti-ONM. With the help of the anti-ONM, we can achieve the same optical illusions where ONM is required via a shelled structure filled with low anisotropic medium, which is easier to realize for some novel optical devices designed by TO and optical surface transformation. The special function of the anti-ONM will lead to a new way to design optical devices or simplify the material requirements. Overlapping illusions, and wave-front reshapers are designed to demonstrate the function of the proposed method.

Instabilities and the null energy condition

International Nuclear Information System (INIS)

Buniy, Roman V.; Hsu, Stephen D.H.

2006-01-01

We show that violation of the null energy condition implies instability in a broad class of models, including gauge theories with scalar and fermionic matter as well as any perfect fluid. When applied to the dark energy, our results imply that w=p/ρ is unlikely to be less than -1. than -1

A semi-discrete integrable multi-component coherently coupled nonlinear Schrödinger system

International Nuclear Information System (INIS)

Zhao, Hai-qiong; Yuan, Jinyun

2016-01-01

A new integrable semi-discrete version is proposed for the multi-component coherently coupled nonlinear Schrödinger equation. The integrability of the semi-discrete system is confirmed by existence of Lax pair and infinite number of conservation laws. With the aid of gauge transformations, explicit formulas for N -fold Darboux transformations are derived whereby some physically important solutions of the system are presented. Furthermore, the theory of the semi-discrete system including Lax pair, Darboux transformations, exact solutions and infinite number of conservation laws are shown for their continuous counterparts in the continuous limit. (paper)

OBSERVATION OF MAGNETIC RECONNECTION AT A 3D NULL POINT ASSOCIATED WITH A SOLAR ERUPTION

International Nuclear Information System (INIS)

Sun, J. Q.; Yang, K.; Cheng, X.; Ding, M. D.; Zhang, J.

2016-01-01

Magnetic null has long been recognized as a special structure serving as a preferential site for magnetic reconnection (MR). However, the direct observational study of MR at null-points is largely lacking. Here, we show the observations of MR around a magnetic null associated with an eruption that resulted in an M1.7 flare and a coronal mass ejection. The Geostationary Operational Environmental Satellites X-ray profile of the flare exhibited two peaks at ∼02:23 UT and ∼02:40 UT on 2012 November 8, respectively. Based on the imaging observations, we find that the first and also primary X-ray peak was originated from MR in the current sheet (CS) underneath the erupting magnetic flux rope (MFR). On the other hand, the second and also weaker X-ray peak was caused by MR around a null point located above the pre-eruption MFR. The interaction of the null point and the erupting MFR can be described as a two-step process. During the first step, the erupting and fast expanding MFR passed through the null point, resulting in a significant displacement of the magnetic field surrounding the null. During the second step, the displaced magnetic field started to move back, resulting in a converging inflow and subsequently the MR around the null. The null-point reconnection is a different process from the current sheet reconnection in this flare; the latter is the cause of the main peak of the flare, while the former is the cause of the secondary peak of the flare and the conspicuous high-lying cusp structure.

Parallel-propagated frame along null geodesics in higher-dimensional black hole spacetimes

International Nuclear Information System (INIS)

Kubiznak, David; Frolov, Valeri P.; Connell, Patrick; Krtous, Pavel

2009-01-01

In [arXiv:0803.3259] the equations describing the parallel transport of orthonormal frames along timelike (spacelike) geodesics in a spacetime admitting a nondegenerate principal conformal Killing-Yano 2-form h were solved. The construction employed is based on studying the Darboux subspaces of the 2-form F obtained as a projection of h along the geodesic trajectory. In this paper we demonstrate that, although slightly modified, a similar construction is possible also in the case of null geodesics. In particular, we explicitly construct the parallel-transported frames along null geodesics in D=4, 5, 6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport along principal null directions in these spacetimes. Such directions coincide with the eigenvectors of the principal conformal Killing-Yano tensor. Finally, we show how to obtain a parallel-transported frame along null geodesics in the background of the 4D Plebanski-Demianski metric which admits only a conformal generalization of the Killing-Yano tensor.

On the geometry of null cones to infinity under curvature flux bounds

International Nuclear Information System (INIS)

Alexakis, Spyros; Shao, Arick

2014-01-01

The main objective of this paper is to control the geometry of a future outgoing truncated null cone extending smoothly toward infinity in an Einstein-vacuum spacetime. In particular, we wish to do this under minimal regularity assumptions, namely, at the (weighted) L 2 -curvature level. We show that if the curvature flux and the data on an initial sphere of the cone are sufficiently close to the corresponding values in a standard Minkowski or Schwarzschild null cone, then we can obtain quantitative bounds on the geometry of the entire infinite cone. The same bounds also imply the existence of limits at infinity, along the null cone, of naturally scaled geometric quantities. In Alexakis and Shao (2013 Bounds on the Bondi energy by a flux of curvature arXiv:1308.4170), we will apply these results in order to control various physical quantities—e.g., the Bondi energy and (linear and angular) momenta—associated with such infinite null cones in vacuum spacetimes. (paper)

Simple Fourier optics formalism for high-angular-resolution systems and nulling interferometry.

Science.gov (United States)

Hénault, François

2010-03-01

Reviewed are various designs of advanced, multiaperture optical systems dedicated to high-angular-resolution imaging or to the detection of exoplanets by nulling interferometry. A simple Fourier optics formalism applicable to both imaging arrays and nulling interferometers is presented, allowing their basic theoretical relationships to be derived as convolution or cross-correlation products suitable for fast and accurate computation. Several unusual designs, such as a "superresolving telescope" utilizing a mosaicking observation procedure or a free-flying, axially recombined interferometer are examined, and their performance in terms of imaging and nulling capacity are assessed. In all considered cases, it is found that the limiting parameter is the diameter of the individual telescopes. A final section devoted to nulling interferometry shows an apparent superiority of axial versus multiaxial recombining schemes. The entire study is valid only in the framework of first-order geometrical optics and scalar diffraction theory. Furthermore, it is assumed that all entrance subapertures are optically conjugated with their associated exit pupils.

Performance analysis of hybrid ground-coupled heat pump system with multi-functions

International Nuclear Information System (INIS)

You, Tian; Wang, Baolong; Wu, Wei; Shi, Wenxing; Li, Xianting

2015-01-01

Highlights: • The hybrid GCHP system with multi-functions is proposed. • The system maintains the soil temperature and heating reliability steady. • The multi-functional operation of HCUT can save more energy of the system. - Abstract: Underground thermal imbalance is a significant problem for ground-coupled heat pump (GCHP) systems that serve predominately heated buildings in cold regions, which extract more heat from the ground and inject less heat, especially in buildings requiring domestic hot water (DHW). To solve this problem, a previously developed heat compensation unit with thermosyphon (HCUT) is integrated with a GCHP unit to build a hybrid GCHP system. To improve the energy savings of this hybrid GCHP system, the HCUT unit is set to have multiple functions (heat compensation, direct DHW and direct space heating) in this paper. To analyze the improved system performance, a hotel requiring air-conditioning and DHW is selected and simulated in three typical cold cities using the dynamic software DeST and TRNSYS. The results indicate that the hybrid GCHP system can maintain the underground thermal balance while keeping the indoor air temperature within the design range. Furthermore, the HCUT unit efficiently reduces the energy consumption via its multi-functional operations. Compared to the previous system that only used HCUT for heat compensation, adding the direct DHW function further saves 7.5–11.0% energy in heat compensation (HC) and DHW (i.e., 3.6–4.8% of the whole system). Simultaneously adding the direct DHW and space heating functions to the HCUT can save 9.8–12.9% energy in HC and DHW (i.e., 5.1–6.0% of the whole system). The hybrid GCHP system with a multi-functional HCUT provides more energy savings while maintaining the underground thermal balance in cold regions that demand both air-conditioning and DHW

Mode Theory of Multi-Armed Spiral Antennas and Its Application to Electronic Warfare Antennas

Science.gov (United States)

Radway, Matthew J.

Since their invention about 55 years ago, spiral antennas have earned a reputation for providing stable impedance and far-field patterns over multi-decade frequency ranges. For the first few decades these antennas were researched for electronic warfare receiving applications, primarily in the 2-18 GHz range. This research was often done under conditions of secrecy, and often by private contractors who did not readily share their research, and now have been defunct for decades. Even so, the body of literature on the two-armed variant of these antennas is rich, often leading non-specialists to the misconception that these antennas are completely understood. Furthermore, early work was highly experimental in nature, and was conducted before modern data collection and postprocessing capabilities were widespread, which limited the range of the studies. Recent research efforts have focused on extending the application of spirals into new areas, as well as applying exotic materials to `improve' their performance and reduce their size. While interesting results have been obtained, in most instances these were incomplete, often compromising the frequency independent nature of these antennas. This thesis expands the role of the multi-armed spiral outside of its traditional niche of receive-only monopulse direction finding. As a first step, careful study of the spiral-antenna mode theory is undertaken with particular attention paid to the concepts of mode filtering and modal decomposition. A technique for reducing the modal impedance of high arm-count spirals is introduced. The insights gained through this theoretical study are first used to improve the far-field performance of the coiled-arm spiral antenna. Specifically, expanding the number of arms on a coiled arm spiral from two to four while providing proper excitation enables dramatically improved broadside axial ratio and azimuthal pattern uniformity. The multiarming technique is then applied to the design of an antenna

Abnormal Activation of BMP Signaling Causes Myopathy in Fbn2 Null Mice.

Directory of Open Access Journals (Sweden)

Gerhard Sengle

2015-06-01

Full Text Available Fibrillins are large extracellular macromolecules that polymerize to form the backbone structure of connective tissue microfibrils. Mutations in the gene for fibrillin-1 cause the Marfan syndrome, while mutations in the gene for fibrillin-2 cause Congenital Contractural Arachnodactyly. Both are autosomal dominant disorders, and both disorders affect musculoskeletal tissues. Here we show that Fbn2 null mice (on a 129/Sv background are born with reduced muscle mass, abnormal muscle histology, and signs of activated BMP signaling in skeletal muscle. A delay in Myosin Heavy Chain 8, a perinatal myosin, was found in Fbn2 null forelimb muscle tissue, consistent with the notion that muscle defects underlie forelimb contractures in these mice. In addition, white fat accumulated in the forelimbs during the early postnatal period. Adult Fbn2 null mice are already known to demonstrate persistent muscle weakness. Here we measured elevated creatine kinase levels in adult Fbn2 null mice, indicating ongoing cycles of muscle injury. On a C57Bl/6 background, Fbn2 null mice showed severe defects in musculature, leading to neonatal death from respiratory failure. These new findings demonstrate that loss of fibrillin-2 results in phenotypes similar to those found in congenital muscular dystrophies and that FBN2 should be considered as a candidate gene for recessive congenital muscular dystrophy. Both in vivo and in vitro evidence associated muscle abnormalities and accumulation of white fat in Fbn2 null mice with abnormally activated BMP signaling. Genetic rescue of reduced muscle mass and accumulation of white fat in Fbn2 null mice was accomplished by deleting a single allele of Bmp7. In contrast to other reports that activated BMP signaling leads to muscle hypertrophy, our findings demonstrate the exquisite sensitivity of BMP signaling to the fibrillin-2 extracellular environment during early postnatal muscle development. New evidence presented here suggests that

Pattern Nulling of Linear Antenna Arrays Using Backtracking Search Optimization Algorithm

Directory of Open Access Journals (Sweden)

Kerim Guney

2015-01-01

Full Text Available An evolutionary method based on backtracking search optimization algorithm (BSA is proposed for linear antenna array pattern synthesis with prescribed nulls at interference directions. Pattern nulling is obtained by controlling only the amplitude, position, and phase of the antenna array elements. BSA is an innovative metaheuristic technique based on an iterative process. Various numerical examples of linear array patterns with the prescribed single, multiple, and wide nulls are given to illustrate the performance and flexibility of BSA. The results obtained by BSA are compared with the results of the following seventeen algorithms: particle swarm optimization (PSO, genetic algorithm (GA, modified touring ant colony algorithm (MTACO, quadratic programming method (QPM, bacterial foraging algorithm (BFA, bees algorithm (BA, clonal selection algorithm (CLONALG, plant growth simulation algorithm (PGSA, tabu search algorithm (TSA, memetic algorithm (MA, nondominated sorting GA-2 (NSGA-2, multiobjective differential evolution (MODE, decomposition with differential evolution (MOEA/D-DE, comprehensive learning PSO (CLPSO, harmony search algorithm (HSA, seeker optimization algorithm (SOA, and mean variance mapping optimization (MVMO. The simulation results show that the linear antenna array synthesis using BSA provides low side-lobe levels and deep null levels.

Partial null astigmatism-compensated interferometry for a concave freeform Zernike mirror

Science.gov (United States)

Dou, Yimeng; Yuan, Qun; Gao, Zhishan; Yin, Huimin; Chen, Lu; Yao, Yanxia; Cheng, Jinlong

2018-06-01

Partial null interferometry without using any null optics is proposed to measure a concave freeform Zernike mirror. Oblique incidence on the freeform mirror is used to compensate for astigmatism as the main component in its figure, and to constrain the divergence of the test beam as well. The phase demodulated from the partial nulled interferograms is divided into low-frequency phase and high-frequency phase by Zernike polynomial fitting. The low-frequency surface figure error of the freeform mirror represented by the coefficients of Zernike polynomials is reconstructed from the low-frequency phase, applying the reverse optimization reconstruction technology in the accurate model of the interferometric system. The high-frequency surface figure error of the freeform mirror is retrieved from the high-frequency phase adopting back propagating technology, according to the updated model in which the low-frequency surface figure error has been superimposed on the sag of the freeform mirror. Simulations verified that this method is capable of testing a wide variety of astigmatism-dominated freeform mirrors due to the high dynamic range. The experimental result using our proposed method for a concave freeform Zernike mirror is consistent with the null test result employing the computer-generated hologram.

Apoptosis in spermatogonia irradiated P53 null mice

International Nuclear Information System (INIS)

Streit-Bianchi, M.; Hendry, J.H.; Roberts, S.A.; Morris, J.D.; Durgaryan, A.A.

2007-01-01

Complete text of publication follows. The exposure of germ cells to ionizing radiations is of concern both from high-dose therapeutic exposures and from low doses causing deleterious trans-generational mutations. P53 protein plays an important role in cellular damage and is expressed in the testis normally during meiosis, its expression being localised to the preleptotene and early/mid pachytene spermatocytes. P53 null mice, heterozygotes possessing a 129 Sv/C57BL6 genetic background and B6D2F1 mice have been irradiated to 1 and 2 Gy single doses. Fractionated exposures of 1+1 Gy at 4 hours interval were also carried out. Apoptosis induction, spermatogonia and spermatocytes survival were assessed by microscope analysis of histological samples at 4 to 96 hours after irradiation in time-course experiments. The same end-points were also assessed at 72 and 96 hours after irradiation to single doses in the region between 20cGy to 2Gy. A dose dependent level of p53 expression was observed at 4 hours after irradiation to 1 and 2 Gy which returned to normal level by 24 hours. Our data support a two process mode of apoptosis with a first wave around 12 hours followed by a second wave at 2-3 days. The first wave apoptosis is substantially reduced in p53 null mice whereas the second wave is reduced in B6D2F1 mice. The initial increase in apoptosis was delayed in some stages of the of germ cells development which were identified by the spermatids shape. Clear correlation exists between apoptosis and survival assessed in stage XI-XII Tubules 72 hours after irradiation. The data are in agreement with other data in literature indicating that irradiated spermatogonia die through apoptosis. The lack of apoptosis observed in p53 null mice results in a very high survival rate of daughter cells assessed later. Theses spermatocytes and the following progenitor cells are likely to carry mutations as most will not die in the smaller second wave of apoptosis observed 3 days after

Vortical null orbits, repulsive barriers, energy confinement in Kerr metric

Energy Technology Data Exchange (ETDEWEB)

Calvani, M [Padua Univ. (Italy). Ist. di Astronomia; De Felice, F

1978-10-01

The complete analytical description of the null trajectories in the field of a Kerr naked singularity is given. Two peculiar phenomena are described: the existence of repulsive barriers in the r < O world and the existence of null circular bound orbits which surround the singularity in 'shells'. They distribute around the surface at r = m, which is the position of the horizon in the extreme black-hole case; this suggests that a naked singularity 'remembers' the position of the last horizon.

Future null infinity of Robertson-Walker spacetimes

International Nuclear Information System (INIS)

Moreschi, O.M.

1988-08-01

The future null infinity for all non-contracting Robertson-Walker space time is studied systematically. A theorem is proved which establishes the expected relation between the nature of J + and the appearance or absence of cosmic event horizons. (author). 7 refs, 1 tab

Modeling of coupling mechanism of wireless power transfer system and vibration phenomenon of receiver-coil in three-coil system

Directory of Open Access Journals (Sweden)

Suqi Liu

2017-11-01

Full Text Available Wireless power transfer (WPT via coupled magnetic resonances has become a focus recently, but the mechanisms responsible for such work are uncertain. We found that WPT system is a self-organization system by utilizing self-organization theory to judge. Firstly, the circuit model was established and transfer characteristic of a system was researched by utilizing circuit theories. Thus, with the introduction of entropy variable S, the energy equation of state can be established from the energy of the transmitter side and the energy of the receiver side. According to the energy equation of state, this paper obtains two equations when the reactance of the transmitter side and the receiver side equate to zero respectively. The vibration phenomenon of the receiver-coil in a three-coil WPT system was predicted and explained. Our findings illuminate the unusual self-organization in the WPT system and explain the vibration phenomenon of the receiver-coil in a three-coil WPT system.

Modeling of coupling mechanism of wireless power transfer system and vibration phenomenon of receiver-coil in three-coil system

Science.gov (United States)

Liu, Suqi; Tan, Jianping; Wen, Xue

2017-11-01

Wireless power transfer (WPT) via coupled magnetic resonances has become a focus recently, but the mechanisms responsible for such work are uncertain. We found that WPT system is a self-organization system by utilizing self-organization theory to judge. Firstly, the circuit model was established and transfer characteristic of a system was researched by utilizing circuit theories. Thus, with the introduction of entropy variable S, the energy equation of state can be established from the energy of the transmitter side and the energy of the receiver side. According to the energy equation of state, this paper obtains two equations when the reactance of the transmitter side and the receiver side equate to zero respectively. The vibration phenomenon of the receiver-coil in a three-coil WPT system was predicted and explained. Our findings illuminate the unusual self-organization in the WPT system and explain the vibration phenomenon of the receiver-coil in a three-coil WPT system.

Multi-field coupled sensing network for health monitoring of composite bolted joint

Science.gov (United States)

Wang, Yishou; Qing, Xinlin; Dong, Liang; Banerjee, Sourav

2016-04-01

Advanced fiber reinforced composite materials are becoming the main structural materials of next generation of aircraft because of their high strength and stiffness to weight ratios, and excellent designability. As key components of large composite structures, joints play important roles to ensure the integrity of the composite structures. However, it is very difficult to analyze the strength and failure modes of composite joints due to their complex nonlinear coupling factors. Therefore, there is a need to monitor, diagnose, evaluate and predict the structure state of composite joints. This paper proposes a multi-field coupled sensing network for health monitoring of composite bolted joints. Major work of this paper includes: 1) The concept of multifunctional sensor layer integrated with eddy current sensors, Rogowski coil and arrayed piezoelectric sensors; 2) Development of the process for integrating the eddy current sensor foil, Rogowski coil and piezoelectric sensor array in multifunctional sensor layer; 3) A new concept of smart composite joint with multifunctional sensing capability. The challenges for building such a structural state sensing system and some solutions to address the challenges are also discussed in the study.

Multi-State Vibronic Interactions in Fluorinated Benzene Radical Cations.

Science.gov (United States)

Faraji, S.; Köppel, H.

2009-06-01

Conical intersections of potential energy surfaces have emerged as paradigms for signalling strong nonadiabatic coupling effects. An important class of systems where some of these effects have been analyzed in the literature, are the benzene and benzenoid cations, where the electronic structure, spectroscopy, and dynamics have received great attention in the literature. In the present work a brief overview is given over our theoretical treatments of multi-mode and multi-state vibronic interactions in the benzene radical cation and some of its fluorinated derivatives. The fluorobenzene derivatives are of systematic interest for at least two different reasons. (1) The reduction of symmetry by incomplete fluorination leads to a disappearance of the Jahn-Teller effect present in the parent cation. (2) A specific, more chemical effect of fluorination consists in the energetic increase of the lowest σ-type electronic states of the radical cations. The multi-mode multi-state vibronic interactions between the five lowest electronic states of the fluorobenzene radical cations are investigated theoretically, based on ab initio electronic structure data, and employing the well-established linear vibronic coupling model, augmented by quadratic coupling terms for the totally symmetric vibrational modes. Low-energy conical intersections, and strong vibronic couplings are found to prevail within the set of tilde{X}-tilde{A} and tilde{B}-tilde{C}-tilde{D} cationic states, while the interactions between these two sets of states are found to be weaker and depend on the particular isomer. This is attributed to the different location of the minima of the various conical intersections occurring in these systems. Wave-packet dynamical simulations for these coupled potential energy surfaces, utilizing the powerful multi-configuration time-dependent Hartree method are performed. Ultrafast internal conversion processes and the analysis of the MATI and photo-electron spectra shed new light

Influence of choice of null network on small-world parameters of structural correlation networks.

Directory of Open Access Journals (Sweden)

S M Hadi Hosseini

Full Text Available In recent years, coordinated variations in brain morphology (e.g., volume, thickness have been employed as a measure of structural association between brain regions to infer large-scale structural correlation networks. Recent evidence suggests that brain networks constructed in this manner are inherently more clustered than random networks of the same size and degree. Thus, null networks constructed by randomizing topology are not a good choice for benchmarking small-world parameters of these networks. In the present report, we investigated the influence of choice of null networks on small-world parameters of gray matter correlation networks in healthy individuals and survivors of acute lymphoblastic leukemia. Three types of null networks were studied: 1 networks constructed by topology randomization (TOP, 2 networks matched to the distributional properties of the observed covariance matrix (HQS, and 3 networks generated from correlation of randomized input data (COR. The results revealed that the choice of null network not only influences the estimated small-world parameters, it also influences the results of between-group differences in small-world parameters. In addition, at higher network densities, the choice of null network influences the direction of group differences in network measures. Our data suggest that the choice of null network is quite crucial for interpretation of group differences in small-world parameters of structural correlation networks. We argue that none of the available null models is perfect for estimation of small-world parameters for correlation networks and the relative strengths and weaknesses of the selected model should be carefully considered with respect to obtained network measures.

Influence of Choice of Null Network on Small-World Parameters of Structural Correlation Networks

Science.gov (United States)

Hosseini, S. M. Hadi; Kesler, Shelli R.

2013-01-01

In recent years, coordinated variations in brain morphology (e.g., volume, thickness) have been employed as a measure of structural association between brain regions to infer large-scale structural correlation networks. Recent evidence suggests that brain networks constructed in this manner are inherently more clustered than random networks of the same size and degree. Thus, null networks constructed by randomizing topology are not a good choice for benchmarking small-world parameters of these networks. In the present report, we investigated the influence of choice of null networks on small-world parameters of gray matter correlation networks in healthy individuals and survivors of acute lymphoblastic leukemia. Three types of null networks were studied: 1) networks constructed by topology randomization (TOP), 2) networks matched to the distributional properties of the observed covariance matrix (HQS), and 3) networks generated from correlation of randomized input data (COR). The results revealed that the choice of null network not only influences the estimated small-world parameters, it also influences the results of between-group differences in small-world parameters. In addition, at higher network densities, the choice of null network influences the direction of group differences in network measures. Our data suggest that the choice of null network is quite crucial for interpretation of group differences in small-world parameters of structural correlation networks. We argue that none of the available null models is perfect for estimation of small-world parameters for correlation networks and the relative strengths and weaknesses of the selected model should be carefully considered with respect to obtained network measures. PMID:23840672

A full-spectrum analysis of high-speed train interior noise under multi-physical-field coupling excitations

Science.gov (United States)

Zheng, Xu; Hao, Zhiyong; Wang, Xu; Mao, Jie

2016-06-01

High-speed-railway-train interior noise at low, medium, and high frequencies could be simulated by finite element analysis (FEA) or boundary element analysis (BEA), hybrid finite element analysis-statistical energy analysis (FEA-SEA) and statistical energy analysis (SEA), respectively. First, a new method named statistical acoustic energy flow (SAEF) is proposed, which can be applied to the full-spectrum HST interior noise simulation (including low, medium, and high frequencies) with only one model. In an SAEF model, the corresponding multi-physical-field coupling excitations are firstly fully considered and coupled to excite the interior noise. The interior noise attenuated by sound insulation panels of carriage is simulated through modeling the inflow acoustic energy from the exterior excitations into the interior acoustic cavities. Rigid multi-body dynamics, fast multi-pole BEA, and large-eddy simulation with indirect boundary element analysis are first employed to extract the multi-physical-field excitations, which include the wheel-rail interaction forces/secondary suspension forces, the wheel-rail rolling noise, and aerodynamic noise, respectively. All the peak values and their frequency bands of the simulated acoustic excitations are validated with those from the noise source identification test. Besides, the measured equipment noise inside equipment compartment is used as one of the excitation sources which contribute to the interior noise. Second, a full-trimmed FE carriage model is firstly constructed, and the simulated modal shapes and frequencies agree well with the measured ones, which has validated the global FE carriage model as well as the local FE models of the aluminum alloy-trim composite panel. Thus, the sound transmission loss model of any composite panel has indirectly been validated. Finally, the SAEF model of the carriage is constructed based on the accurate FE model and stimulated by the multi-physical-field excitations. The results show

On Bäcklund transformation and vortex filament equation for null Cartan curve in Minkowski 3-space

Energy Technology Data Exchange (ETDEWEB)

Grbović, Milica, E-mail: milica.grbovic@kg.ac.rs; Nešović, Emilija, E-mail: nesovickg@sbb.rs [University of Kragujevac, Faculty of Science, Department of Mathematics and Informatics (Serbia)

2016-12-15

In this paper we introduce Bäcklund transformation of a null Cartan curve in Minkowski 3-space as a transformation which maps a null Cartan helix to another null Cartan helix, congruent to the given one. We also give the sufficient conditions for a transformation between two null Cartan curves in the Minkowski 3-space such that these curves have equal constant torsions. By using the Da Rios vortex filament equation, based on localized induction approximation, we derive the vortex filament equation for a null Cartan curve and obtain evolution equation for it’s torsion. As an application, we show that Cartan’s frame vectors generate new solutions of the Da Rios vortex filament equation.

Left cardiac isomerism in the Sonic hedgehog null mouse.

Science.gov (United States)

Hildreth, Victoria; Webb, Sandra; Chaudhry, Bill; Peat, Jonathan D; Phillips, Helen M; Brown, Nigel; Anderson, Robert H; Henderson, Deborah J

2009-06-01

Sonic hedgehog (Shh) is a secreted morphogen necessary for the production of sidedness in the developing embryo. In this study, we describe the morphology of the atrial chambers and atrioventricular junctions of the Shh null mouse heart. We demonstrate that the essential phenotypic feature is isomerism of the left atrial appendages, in combination with an atrioventricular septal defect and a common atrioventricular junction. These malformations are known to be frequent in humans with left isomerism. To confirm the presence of left isomerism, we show that Pitx2c, a recognized determinant of morphological leftness, is expressed in the Shh null mutants on both the right and left sides of the inflow region, and on both sides of the solitary arterial trunk exiting from the heart. It has been established that derivatives of the second heart field expressing Isl1 are asymmetrically distributed in the developing normal heart. We now show that this population is reduced in the hearts from the Shh null mutants, likely contributing to the defects. To distinguish the consequences of reduced contributions from the second heart field from those of left-right patterning disturbance, we disrupted the movement of second heart field cells into the heart by expressing dominant-negative Rho kinase in the population of cells expressing Isl1. This resulted in absence of the vestibular spine, and presence of atrioventricular septal defects closely resembling those seen in the hearts from the Shh null mutants. The primary atrial septum, however, was well formed, and there was no evidence of isomerism of the atrial appendages, suggesting that these features do not relate to disruption of the contributions made by the second heart field. We demonstrate, therefore, that the Shh null mouse is a model of isomerism of the left atrial appendages, and show that the recognized associated malformations found at the venous pole of the heart in the setting of left isomerism are likely to arise from

Kastor-Traschen black holes, null geodesics and conformal circles

International Nuclear Information System (INIS)

Casey, Stephen

2012-01-01

The Kastor-Traschen metric is a time-dependent solution of the Einstein-Maxwell equations with positive cosmological constant Λ which can be used to describe an arbitrary number of charged dynamical black holes. In this paper, we consider the null geodesic structure of this solution, in particular, focusing on the projection to the space of orbits of the timelike conformal retraction. It is found that these projected light rays arise as integral curves of a system of third-order ordinary differential equations. This system is not uniquely defined, however, and we use the inherent freedom to construct a new system whose integral curves coincide with the projection of distinguished null curves of Kastor-Traschen arising from a magnetic flow. We discuss our results in the one-centre case and demonstrate a link to conformal circles in the limit Λ → 0. We also show how to construct analytic expressions for the projected null geodesics of this metric by exploiting a well-known diffeomorphism between the K-T metric and extremal Reissner-Nordstrom-de Sitter. We make some remarks about the two-centre solution and demonstrate a link with the one-centre case. (paper)

G protein-coupled receptor 39 deficiency is associated with pancreatic islet dysfunction

DEFF Research Database (Denmark)

Holst, Birgitte; Egerod, Kristoffer L; Jin, Chunyu

2009-01-01

G protein-coupled receptor (GPR)-39 is a seven-transmembrane receptor expressed mainly in endocrine and metabolic tissues that acts as a Zn(++) sensor signaling mainly through the G(q) and G(12/13) pathways. The expression of GPR39 is regulated by hepatocyte nuclear factor (HNF)-1alpha and HNF-4...... tolerance both during oral and iv glucose tolerance tests, and Gpr39(-/-) mice had decreased plasma insulin response to oral glucose. Islet architecture was normal in the Gpr39 null mice, but expression of Pdx-1 and Hnf-1alpha was reduced. Isolated, perifused islets from Gpr39 null mice secreted less...

Characterisation of nuclear fuel samples by quadrupole and multi-collector inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Wernli, Beath; Guenther-Leopold, Ines; Kobler Waldis, Judith; Kopajtic, Zlatan

2003-01-01

The characterisation of nuclear fuel cycle materials for trace and minor metallic constituents is of great interest for the nuclear industry and safeguard officials. The main objective of various international programmes dealing with postirradiation examinations is to improve the knowledge of the inventories of actinides, fission and spallation products in spent nuclear fuels. The low detection limits for a large number of elements combined with the ability to analyse the isotopic composition of the elements have established inductively coupled plasma mass spectrometry (ICP-MS) as a powerful multi-element technique in diverse analytical applications for the characterisation of nuclear materials. Because numerous isobaric overlaps restrict the direct determination of many fission products by mass spectrometry, extensive chemical separations are required for these elements. In order to simplify this sample preparation procedure, a high performance liquid chromatography system (HPLC) was online coupled to the mass spectrometer. Since about 10 years a quadrupole based ICP-MS (Q-ICP-MS) combined with an HPLC is used within the Hot Laboratory of the Paul Scherrer Institut for different applications on nuclear fuel samples. Since May 2003 also a new multi-collector ICP-MS (MC-ICP-MS) is used for the mass spectrometric characterisation of nuclear fuel samples, especially for the precise determination of the isotopic vectors of fission products and actinides. Therefore, two complementary analytical systems are now available in the group of 'Isotope and Wet Analytical Chemistry'. A comparison of the analytical performance of both systems (with and without an online coupled HPLC system) for the determination of the isotopic composition and the elemental concentration of different nuclides in nuclear fuel samples, the advantages and limitations of both techniques, the accuracy and precision of the results and typical applications for both methods will be discussed in the

Recent developments with the visible nulling coronagraph

Science.gov (United States)

Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter; Helmbrecht, Michael A.; Howard, Joseph M.; Miller, Ian J.

2016-08-01

A wide array of general astrophysics studies including detecting and characterizing habitable exoplanets could be enabled by a future large segmented telescope with sensitivity in the UV, optical, and infrared bands. When paired with a starshade or coronagraph, such an observatory could enable direct imaging and detailed spectroscopic observations of nearby Earth-like habitable zone planets. Over the past several years, a laboratory-based Visible Nulling Coronagraph (VNC) has evolved to reach requisite contrasts over a 1 nm bandwidth at narrow source angle separation using a segmented deformable mirror in one arm of a Mach-Zehnder layout. More recent efforts targeted broadband performance following the addition of two sets of half-wave Fresnel rhomb achromatic phase shifters (APS) with the goal of reaching 10-9 contrast, at a separation of 2λ/D, using a 40 nm (6%) bandwidth single mode fiber source. Here we present updates on the VNC broadband nulling effort, including approaches to addressing system contrast limitations.

Noncolocated Time-Reversal MUSIC: High-SNR Distribution of Null Spectrum

Science.gov (United States)

Ciuonzo, Domenico; Rossi, Pierluigi Salvo

2017-04-01

We derive the asymptotic distribution of the null spectrum of the well-known Multiple Signal Classification (MUSIC) in its computational Time-Reversal (TR) form. The result pertains to a single-frequency non-colocated multistatic scenario and several TR-MUSIC variants are here investigated. The analysis builds upon the 1st-order perturbation of the singular value decomposition and allows a simple characterization of null-spectrum moments (up to the 2nd order). This enables a comparison in terms of spectrums stability. Finally, a numerical analysis is provided to confirm the theoretical findings.

Super-pixel extraction based on multi-channel pulse coupled neural network

Science.gov (United States)

Xu, GuangZhu; Hu, Song; Zhang, Liu; Zhao, JingJing; Fu, YunXia; Lei, BangJun

2018-04-01

Super-pixel extraction techniques group pixels to form over-segmented image blocks according to the similarity among pixels. Compared with the traditional pixel-based methods, the image descripting method based on super-pixel has advantages of less calculation, being easy to perceive, and has been widely used in image processing and computer vision applications. Pulse coupled neural network (PCNN) is a biologically inspired model, which stems from the phenomenon of synchronous pulse release in the visual cortex of cats. Each PCNN neuron can correspond to a pixel of an input image, and the dynamic firing pattern of each neuron contains both the pixel feature information and its context spatial structural information. In this paper, a new color super-pixel extraction algorithm based on multi-channel pulse coupled neural network (MPCNN) was proposed. The algorithm adopted the block dividing idea of SLIC algorithm, and the image was divided into blocks with same size first. Then, for each image block, the adjacent pixels of each seed with similar color were classified as a group, named a super-pixel. At last, post-processing was adopted for those pixels or pixel blocks which had not been grouped. Experiments show that the proposed method can adjust the number of superpixel and segmentation precision by setting parameters, and has good potential for super-pixel extraction.

Hypersensitivities for acetaldehyde and other agents among cancer cells null for clinically relevant Fanconi anemia genes.

Science.gov (United States)

Ghosh, Soma; Sur, Surojit; Yerram, Sashidhar R; Rago, Carlo; Bhunia, Anil K; Hossain, M Zulfiquer; Paun, Bogdan C; Ren, Yunzhao R; Iacobuzio-Donahue, Christine A; Azad, Nilofer A; Kern, Scott E

2014-01-01

Large-magnitude numerical distinctions (>10-fold) among drug responses of genetically contrasting cancers were crucial for guiding the development of some targeted therapies. Similar strategies brought epidemiological clues and prevention goals for genetic diseases. Such numerical guides, however, were incomplete or low magnitude for Fanconi anemia pathway (FANC) gene mutations relevant to cancer in FANC-mutation carriers (heterozygotes). We generated a four-gene FANC-null cancer panel, including the engineering of new PALB2/FANCN-null cancer cells by homologous recombination. A characteristic matching of FANCC-null, FANCG-null, BRCA2/FANCD1-null, and PALB2/FANCN-null phenotypes was confirmed by uniform tumor regression on single-dose cross-linker therapy in mice and by shared chemical hypersensitivities to various inter-strand cross-linking agents and γ-radiation in vitro. Some compounds, however, had contrasting magnitudes of sensitivity; a strikingly high (19- to 22-fold) hypersensitivity was seen among PALB2-null and BRCA2-null cells for the ethanol metabolite, acetaldehyde, associated with widespread chromosomal breakage at a concentration not producing breaks in parental cells. Because FANC-defective cancer cells can share or differ in their chemical sensitivities, patterns of selective hypersensitivity hold implications for the evolutionary understanding of this pathway. Clinical decisions for cancer-relevant prevention and management of FANC-mutation carriers could be modified by expanded studies of high-magnitude sensitivities. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Dall-Null tester for spaceborne applications

Science.gov (United States)

Wingler, R. L.

1984-12-01

This is a study to design a self correcting primary mirror system for a space telescope. The design is centered around a Dall-Null tester (a Foucault knife-edge tester with compensating lens). An indepth study of the theory of the Foucault test from Foucault's original publications to current work is presented. Also short comings of the diffraction approach are shown. The findings of a simple experiment showed the way to the correct explanation as to the workings of the test. Based on this new explanation, a computer program to find the error in the surface of the mirror from the irradiance pattern provided by the Dall-Null tester was developed. The computer program with a sample run is included in the appendixes A and B. The basic design of an adaptive optic system for a spaceborne application is also presented in the paper. This design has the desired quality of being able to correct the mirror while the telescope is in use. The equations being independent of wavelength allows for the design to be applied to systems working outside of the visible spectrum as well as the systems working in the visible.

Development of a coupled neutronic/thermal-hydraulic tool with multi-scale capabilities and applications to HPLWR core analysis

International Nuclear Information System (INIS)

Monti, Lanfranco; Starflinger, Joerg; Schulenberg, Thomas

2011-01-01

Highlights: → Advanced analysis and design techniques for innovative reactors are addressed. → Detailed investigation of a 3 pass core design with a multi-physics-scales tool. → Coupled 40-group neutron transport/equivalent channels TH core analyses methods. → Multi-scale capabilities: from equivalent channels to sub-channel pin-by-pin study. → High fidelity approach: reduction of conservatism involved in core simulations. - Abstract: The High Performance Light Water Reactor (HPLWR) is a thermal spectrum nuclear reactor cooled and moderated with light water operated at supercritical pressure. It is an innovative reactor concept, which requires developing and applying advanced analysis tools as described in the paper. The relevant water density reduction associated with the heat-up, together with the multi-pass core design, results in a pronounced coupling between neutronic and thermal-hydraulic analyses, which takes into account the strong natural influence of the in-core distribution of power generation and water properties. The neutron flux gradients within the multi-pass core, together with the pronounced dependence of water properties on the temperature, require to consider a fine spatial resolution in which the individual fuel pins are resolved to provide precise evaluation of the clad temperature, currently considered as one of the crucial design criteria. These goals have been achieved considering an advanced analysis method based on the usage of existing codes which have been coupled with developed interfaces. Initially neutronic and thermal-hydraulic full core calculations have been iterated until a consistent solution is found to determine the steady state full power condition of the HPLWR core. Results of few group neutronic analyses might be less reliable in case of HPLWR 3-pass core than for conventional LWRs because of considerable changes of the neutron spectrum within the core, hence 40 groups transport theory has been preferred to the

Null-point titration measurements of free magnesium in stored erythrocytes

International Nuclear Information System (INIS)

Bock, J.L.; Yusuf, Y.; Puntillo, E.

1987-01-01

Free intracellular magnesium concentration (Mg/sub i/) was measured in stored human erythrocytes, using null-point titration with ionophore A23187. For cells stored 31 P NMR spectroscopy, which showed a decrease in Mg/sub i/ with storage. However, the NMR measurements are performed with no pretreatment of the cells, while the null-point method requires an initial washing step, which alters pH/sub i/ and may also alter Mg/sub i/. The titration-measured Mg/sub i/ values are still surprisingly low for long-stored cells, considering that depletion of ATP and 2,3-DPG should release bound Mg. Using the titration-measured Mg/sub i/ values along with measurements of total Mg, ATP, and 2,3-DPG, they estimate that an additional buffer contains about 47% of total Mg in cells stored 21 days. Mg/sub i/ determinations by both 31 P NMR and null-point titration thus indicate that erythrocyte Mg is largely bound to a high-capacity, low-affinity buffer whose relative importance increases during cell storage. Discrepancies between the methods require further investigation

Reversing hypomyelination in BACE1-null mice with Akt-DD overexpression.

Science.gov (United States)

Hu, Xiangyou; Schlanger, Rita; He, Wanxia; Macklin, Wendy B; Yan, Riqiang

2013-05-01

β-Site amyloid precursor protein convertase enzyme 1 (BACE1), a type I transmembrane aspartyl protease required to cleave amyloid precursor protein for releasing a toxic amyloid peptide, also cleaves type I and type III neuregulin-1 (Nrg-1). BACE1 deficiency in mice causes hypomyelination during development and impairs remyelination if injured. In BACE1-null mice, the abolished cleavage of neuregulin-1 by BACE1 is speculated to cause reduced myelin sheath thickness in both the central nervous system and peripheral nervous system because reduced cleavage of Nrg-1 correlates with reduced Akt phosphorylation, a downstream signaling molecule of the Nrg-1/ErbB pathway. Here we tested specifically whether increasing Akt activity alone in oligodendrocytes would be sufficient to reverse the hypomyelination phenotype in BACE1-null mice. BACE1-null mice were bred with transgenic mice expressing constitutively active Akt (Akt-DD; mutations with D(308)T and D(473)S) in oligodendrocytes. Relative to littermate BACE1-null controls, BACE1(-/-)/Akt-DD mice exhibited enhanced expression of myelin basic protein and promoter of proteolipid protein. The elevated expression of myelin proteins correlated with a thicker myelin sheath in optic nerves; comparison of quantified g ratios with statistic significance was used to confirm this reversion. However, it appeared that myelin sheath thickness in the sciatic nerves was not increased in BACE1(-/-)/Akt-DD mice, as the g ratio was not significantly different from the control. Hence, increased Akt activity in BACE1-null myelinating cells only compensates for the loss of BACE1 activity in the central nervous system, which is consistent with the observation that overexpression of Akt-DD in Schwann cells did not induce hypermyelination. Our results suggest that signaling activity other than Akt may also contribute to proper myelination in peripheral nerves.

Multi-scale modelling of the physicochemical-mechanical coupling of fuel behaviour at high temperature in pressurized water reactors

International Nuclear Information System (INIS)

Julien, Jerome

2008-01-01

Within the frame of the problematic of pellet-sheath interaction in a nuclear fuel rod, a good description of the fuel thermo-mechanical behaviour is required. This research thesis reports the coupling of physics-chemistry (simulation of gas transfers between different cavities) and mechanics (assessment of fuel viscoplastic strains). A new micromechanical model is developed which uses a multi-scale approach to describe the evolution of the double population of cavities (cavities with two different scales) while taking internal pressures as well as the fuel macroscopic viscoplastic behaviour into account. The author finally describes how to couple this micromechanical mode to physics-chemistry models [fr

The Quantum Focussing Conjecture and Quantum Null Energy Condition

Science.gov (United States)

Koeller, Jason

Evidence has been gathering over the decades that spacetime and gravity are best understood as emergent phenomenon, especially in the context of a unified description of quantum mechanics and gravity. The Quantum Focussing Conjecture (QFC) and Quantum Null Energy Condition (QNEC) are two recently-proposed relationships between entropy and geometry, and energy and entropy, respectively, which further strengthen this idea. In this thesis, we study the QFC and the QNEC. We prove the QNEC in a variety of contexts, including free field theories on Killing horizons, holographic theories on Killing horizons, and in more general curved spacetimes. We also consider the implications of the QFC and QNEC in asymptotically flat space, where they constrain the information content of gravitational radiation arriving at null infinity, and in AdS/CFT, where they are related to other semiclassical inequalities and properties of boundary-anchored extremal area surfaces. It is shown that the assumption of validity and vacuum-state saturation of the QNEC for regions of flat space defined by smooth cuts of null planes implies a local formula for the modular Hamiltonian of these regions. We also demonstrate that the QFC as originally conjectured can be violated in generic theories in d ≥ 5, which led the way to an improved formulation subsequently suggested by Stefan Leichenauer.

Zero emission city. Preliminary study; Null-Emissions-Stadt. Sondierungsstudie

Energy Technology Data Exchange (ETDEWEB)

Diefenbach, N; Enseling, A; Werner, P; Flade, A; Greiff, R; Hennings, D; Muehlich, E; Wullkopf, U; Sturm, P; Kieslich, W; Born, R; Grossklos, M; Hatteh, R; Mueller, K; Ratschow, A; Valouch-Fornoff, C

2002-10-01

The idea of a 'zero emission city' is investigated by the Institut Wohnen und Umwelt on behalf of the Federal Minister of Education and Research. After describing the current situation and defining the key parameters of a 'zero emission city', settlement structures, power supply, production processes and transportation are analyzed and linked with the communal action level to obtain a framework for research, activities and actions. The study ends with recommendations for a research programme 'zero emission city'. (orig.) [German] Die von den Staedten der Industrielaender ausgehenden Emissionen stellen im Hinblick auf die globalen Belastungen wie z.B. Treibhauseffekt, Ozonabbau und Versauerung das Hauptproblem dar. Aus diesem Grunde bietet es sich an, den Gedanken der 'Null-Emissions-Stadt', der Vision einer moeglichst emissionsfreien Stadt, aufzugreifen und auf seine Tragfaehigkeit fuer innovative Handlungsmodelle forschungsstrategisch zu ueberpruefen. Das Bundesministerium fuer Bildung und Forschung hat das Institut Wohnen und Umwelt beauftragt, in einer Sondierungsstudie dieser Fragestellung nachzugehen. Nach der Festlegung der Ausgangsbedingungen und Eckpunkte der Vision 'Null-Emissions-Stadt' und der Analyse der vier Handlungsfelder Siedlungsstrukturen, Energieversorgung, Produktionsprozesse (Kreislaufwirtschaft) und Verkehr werden diese aufgegriffen und mit der kommunalen Handlungsebene verknuepft und zu einem Forschungs-, Handlungs- und moeglichen Aktionsrahmen zusammengefuegt. Die Studie schliesst mit Hinweisen fuer die Gestaltung eines Forschungsprogramms 'Null-Emissions-Stadt'. (orig.)

Shape Memory Investigation of α-Keratin Fibers as Multi-Coupled Stimuli of Responsive Smart Materials

Directory of Open Access Journals (Sweden)

Xueliang Xiao

2017-03-01

Full Text Available Like the water responsive shape memory (SM effect of β-keratin bird feathers, α-keratin hairs either existing broadly in nature are found responsive to many types of coupled stimuli in SM behaviors. In this article, α-keratin hairs were investigated for the combined stimuli of thermo-solvent, solvent-solvent, and UV (radiation-reductant sensitive SM abilities. The related netpoints and switches from the hair molecular networks were identified. The experimental results showed that α-keratin hairs manifested a higher ability of shape fixation under thermal stimulus followed with the stimuli of solvent and UV-radiation. Shape recovery from the hair with a temporarily fixed shape showed a higher recovery ability using solvent than the stimuli of heat and UV-radiation. The effects of coupled stimuli on hair’s shape fixation and recovery and on variations of the crystal, disulfide, and hydrogen bonds were studied systematically. A structural network model was thereafter proposed to interpret the multi-coupled stimuli sensitive SM of α-keratin hair. This original study is expected to provide inspiration for exploring other natural fibers to reveal related smart functions and for making more types of remarkable adapted synthetic materials.

A class of algebraically general solutions of the Einstein-Maxwell equations for non-null electromagnetic fields

International Nuclear Information System (INIS)

Tupper, B.O.J.

1976-01-01

In a previous article (Gen. Rel. Grav.; 6 : 345 (1975)) the Einstein-Maxwell field equations for non-null electromagnetic fields were studied under the conditions that the null tetrad is parallel-propagated along both principal null congruences. A solution with twist and shear, but no expansion, was found and was conjectured to be the only expansion-free solution. Here it is shown that this conjecture is false; the general expansion-free solution is found to be a family of space-times depending on a single constant parameter which is the ratio of the (constant) twists of the two principal null congruences. (author)

Minimizing coupling loss by selection of twist pitch lengths in multi-stage cable-in-conduit conductors

International Nuclear Information System (INIS)

Rolando, G; Nijhuis, A; Devred, A

2014-01-01

The numerical code JackPot-ACDC (van Lanen et al 2010 Cryogenics 50 139–48, van Lanen et al 2011 IEEE Trans. Appl. Supercond. 21 1926–9, van Lanen et al 2012 Supercond. Sci. Technol. 25 025012) allows fast parametric studies of the electro-magnetic performance of cable-in-conduit conductors (CICCs). In this paper the code is applied to the analysis of the relation between twist pitch length sequence and coupling loss in multi-stage ITER-type CICCs. The code shows that in the analysed conductors the coupling loss is at its minimum when the twist pitches of the successive cabling stages have a length ratio close to one. It is also predicted that by careful selection of the stage-to-stage twist pitch ratio, CICCs cabled according to long twist schemes in the initial stages can achieve lower coupling loss than conductors with shorter pitches. The result is validated by AC loss measurements performed on prototype conductors for the ITER Central Solenoid featuring different twist pitch sequences. (paper)

Spectratyping analysis of the islet-reactive T cell repertoire in diabetic NOD Igμnull mice after polyclonal B cell reconstitution

Directory of Open Access Journals (Sweden)

Sercarz Eli E

2011-07-01

Full Text Available Abstract Background Non Obese Diabetic mice lacking B cells (NOD.Igμnull mice do not develop diabetes despite their susceptible background. Upon reconstitution of B cells using a chimera approach, animals start developing diabetes at 20 weeks of age. Methods We have used the spectratyping technique to follow the T cell receptor (TCR V beta repertoire of NOD.Igμnull mice following B cell reconstitution. This technique provides an unbiased approach to understand the kinetics of TCR expansion. We have also analyzed the TCR repertoire of reconstituted animals receiving cyclophosphamide treatment and following tissue transplants to identify common aggressive clonotypes. Results We found that B cell reconstitution of NOD.Igμnull mice induces a polyclonal TCR repertoire in the pancreas 10 weeks later, gradually diversifying to encompass most BV families. Interestingly, these clonotypic BV expansions are mainly confined to the pancreas and are absent from pancreatic lymph nodes or spleens. Cyclophosphamide-induced diabetes at 10 weeks post-B cell reconstitution reorganized the predominant TCR repertoires by removing potential regulatory clonotypes (BV1, BV8 and BV11 and increasing the frequency of others (BV4, BV5S2, BV9, BV16-20. These same clonotypes are more frequently present in neonatal pancreatic transplants under the kidney capsule of B-cell reconstituted diabetic NOD.Igμnull mice, suggesting their higher invasiveness. Phenotypic analysis of the pancreas-infiltrating lymphocytes during diabetes onset in B cell reconstituted animals show a predominance of CD19+ B cells with a B:T lymphocyte ratio of 4:1. In contrast, in other lymphoid organs (pancreatic lymph nodes and spleens analyzed by FACS, the B:T ratio was 1:1. Lymphocytes infiltrating the pancreas secrete large amounts of IL-6 and are of Th1 phenotype after CD3-CD28 stimulation in vitro. Conclusions Diabetes in NOD.Igμnull mice appears to be caused by a polyclonal repertoire of T cell

IMPROVING INTERFEROMETRIC NULL DEPTH MEASUREMENTS USING STATISTICAL DISTRIBUTIONS: THEORY AND FIRST RESULTS WITH THE PALOMAR FIBER NULLER

International Nuclear Information System (INIS)

Hanot, C.; Riaud, P.; Absil, O.; Mennesson, B.; Martin, S.; Liewer, K.; Loya, F.; Mawet, D.; Serabyn, E.

2011-01-01

A new 'self-calibrated' statistical analysis method has been developed for the reduction of nulling interferometry data. The idea is to use the statistical distributions of the fluctuating null depth and beam intensities to retrieve the astrophysical null depth (or equivalently the object's visibility) in the presence of fast atmospheric fluctuations. The approach yields an accuracy much better (about an order of magnitude) than is presently possible with standard data reduction methods, because the astrophysical null depth accuracy is no longer limited by the magnitude of the instrumental phase and intensity errors but by uncertainties on their probability distributions. This approach was tested on the sky with the two-aperture fiber nulling instrument mounted on the Palomar Hale telescope. Using our new data analysis approach alone-and no observations of calibrators-we find that error bars on the astrophysical null depth as low as a few 10 -4 can be obtained in the near-infrared, which means that null depths lower than 10 -3 can be reliably measured. This statistical analysis is not specific to our instrument and may be applicable to other interferometers.

An equation satisfied by the tangent to a shear-free, geodesic, null congruence

International Nuclear Information System (INIS)

Hogan, P.A.; Dublin Inst. for Advanced Studies

1987-01-01

A tensorial equation satisfied by the tangent to a shear-free geodesic, null congruence is presented. If the congruence is neither twist-free nor expansion-free then the equation defines a second, unique, null direction previously obtained, using the spinor formalism, by Somers. Some further properties of the equation are discussed. (orig.)

ON THE NATURE OF RECONNECTION AT A SOLAR CORONAL NULL POINT ABOVE A SEPARATRIX DOME

International Nuclear Information System (INIS)

Pontin, D. I.; Priest, E. R.; Galsgaard, K.

2013-01-01

Three-dimensional magnetic null points are ubiquitous in the solar corona and in any generic mixed-polarity magnetic field. We consider magnetic reconnection at an isolated coronal null point whose fan field lines form a dome structure. Using analytical and computational models, we demonstrate several features of spine-fan reconnection at such a null, including the fact that substantial magnetic flux transfer from one region of field line connectivity to another can occur. The flux transfer occurs across the current sheet that forms around the null point during spine-fan reconnection, and there is no separator present. Also, flipping of magnetic field lines takes place in a manner similar to that observed in the quasi-separatrix layer or slip-running reconnection

An Evolutionary Approach for Bilevel Multi-objective Problems

Science.gov (United States)

Deb, Kalyanmoy; Sinha, Ankur

Evolutionary multi-objective optimization (EMO) algorithms have been extensively applied to find multiple near Pareto-optimal solutions over the past 15 years or so. However, EMO algorithms for solving bilevel multi-objective optimization problems have not received adequate attention yet. These problems appear in many applications in practice and involve two levels, each comprising of multiple conflicting objectives. These problems require every feasible upper-level solution to satisfy optimality of a lower-level optimization problem, thereby making them difficult to solve. In this paper, we discuss a recently proposed bilevel EMO procedure and show its working principle on a couple of test problems and on a business decision-making problem. This paper should motivate other EMO researchers to engage more into this important optimization task of practical importance.

Estimation of Neutral Density in Edge Plasma with Double Null Configuration in EAST

International Nuclear Information System (INIS)

Zhang Ling; Xu Guosheng; Ding Siye; Gao Wei; Wu Zhenwei; Chen Yingjie; Huang Juan; Liu Xiaoju; Zang Qing; Chang Jiafeng; Zhang Wei; Li Yingying; Qian Jinping

2011-01-01

In this work, population coefficients of hydrogen's n = 3 excited state from the hydrogen collisional-radiative (CR) model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients (PECs) of hydrogen Balmer-α (n = 3 → n = 2) (H α ). The results are compared with the PECs from Atomic Data and Analysis Structure (ADAS) database, and a good agreement is found. A magnetic surface-averaged neutral density profile of typical double-null (DN) plasma in EAST is obtained by using FRANTIC, the 1.5-D fluid transport code. It is found that the sum of integral D α and H α emission intensity calculated via the neutral density agrees with the measured results obtained by using the absolutely calibrated multi-channel poloidal photodiode array systems viewing the lower divertor at the last closed flux surface (LCFS). It is revealed that the typical magnetic surface-averaged neutral density at LCFS is about 3.5 x 10 16 m -3 . (magnetically confined plasma)

Clausius entropy for arbitrary bifurcate null surfaces

International Nuclear Information System (INIS)

Baccetti, Valentina; Visser, Matt

2014-01-01

Jacobson’s thermodynamic derivation of the Einstein equations was originally applied only to local Rindler horizons. But at least some parts of that construction can usefully be extended to give meaningful results for arbitrary bifurcate null surfaces. As presaged in Jacobson’s original article, this more general construction sharply brings into focus the questions: is entropy objectively ‘real’? Or is entropy in some sense subjective and observer-dependent? These innocent questions open a Pandora’s box of often inconclusive debate. A consensus opinion, though certainly not universally held, seems to be that Clausius entropy (thermodynamic entropy, defined via a Clausius relation dS=đQ/T) should be objectively real, but that the ontological status of statistical entropy (Shannon or von Neumann entropy) is much more ambiguous, and much more likely to be observer-dependent. This question is particularly pressing when it comes to understanding Bekenstein entropy (black hole entropy). To perhaps further add to the confusion, we shall argue that even the Clausius entropy can often be observer-dependent. In the current article we shall conclusively demonstrate that one can meaningfully assign a notion of Clausius entropy to arbitrary bifurcate null surfaces—effectively defining a ‘virtual Clausius entropy’ for arbitrary ‘virtual (local) causal horizons’. As an application, we see that we can implement a version of the generalized second law (GSL) for this virtual Clausius entropy. This version of GSL can be related to certain (nonstandard) integral variants of the null energy condition. Because the concepts involved are rather subtle, we take some effort in being careful and explicit in developing our framework. In future work we will apply this construction to generalize Jacobson’s derivation of the Einstein equations. (paper)

Null vectors in superconformal quantum field theory

International Nuclear Information System (INIS)

Huang Chaoshang

1993-01-01

The superspace formulation of the N=1 superconformal field theory and superconformal Ward identities are used to give a precise definition of fusion. Using the fusion procedure, superconformally covariant differential equations are derived and consequently a complete and straightforward algorithm for finding null vectors in Verma modules of the Neveu-Schwarz algebra is given. (orig.)

A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors

Science.gov (United States)

Seo, Jiwon; Chen, Yu-Hsuan; De Lorenzo, David S.; Lo, Sherman; Enge, Per; Akos, Dennis; Lee, Jiyun

2011-01-01

Due to their weak received signal power, Global Positioning System (GPS) signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs). However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR) with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU) coupled with a new generation Graphics Processing Unit (GPU) having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities. PMID:22164116

A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors

Directory of Open Access Journals (Sweden)

Dennis Akos

2011-09-01

Full Text Available Due to their weak received signal power, Global Positioning System (GPS signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs. However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU coupled with a new generation Graphics Processing Unit (GPU having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities.

Multi-frequency modes in superconducting resonators: Bridging frequency gaps in off-resonant couplings

Science.gov (United States)

Andersen, Christian Kraglund; Mølmer, Klaus

2015-03-01

A SQUID inserted in a superconducting waveguide resonator imposes current and voltage boundary conditions that makes it suitable as a tuning element for the resonator modes. If such a SQUID element is subject to a periodically varying magnetic flux, the resonator modes acquire frequency side bands. We calculate the multi-frequency eigenmodes and these can couple resonantly to physical systems with different transition frequencies and this makes the resonator an efficient quantum bus for state transfer and coherent quantum operations in hybrid quantum systems. As an example of the application, we determine their coupling to transmon qubits with different frequencies and we present a bi-chromatic scheme for entanglement and gate operations. In this calculation, we obtain a maximally entangled state with a fidelity F = 95 % . Our proposal is competitive with the achievements of other entanglement-gates with superconducting devices and it may offer some advantages: (i) There is no need for additional control lines and dephasing associated with the conventional frequency tuning of qubits. (ii) When our qubits are idle, they are far detuned with respect to each other and to the resonator, and hence they are immune to cross talk and Purcell-enhanced decay.

Wireless receiver architectures and design antennas, RF, synthesizers, mixed signal, and digital signal processing

CERN Document Server

Rouphael, Tony J

2014-01-01

Wireless Receiver Architectures and Design presents the various designs and architectures of wireless receivers in the context of modern multi-mode and multi-standard devices. This one-stop reference and guide to designing low-cost low-power multi-mode, multi-standard receivers treats analog and digital signal processing simultaneously, with equal detail given to the chosen architecture and modulating waveform. It provides a complete understanding of the receiver's analog front end and the digital backend, and how each affects the other. The book explains the design process in great detail, s

An inductorless multi-mode RF front end for GNSS receiver in 55 nm CMOS

Science.gov (United States)

Yanbin, Luo; Chengyan, Ma; Yebing, Gan; Min, Qian; Tianchun, Ye

2015-10-01

An inductorless multi-mode RF front end for a global navigation satellite system (GNSS) receiver is presented. Unlike the traditional topology of a low noise amplifier (LNA), the inductorless current-mode noise-canceling LNA is applied in this design. The high-impedance-input radio frequency amplifier (RFA) further amplifies the GNSS signals and changes the single-end signal path into fully differential. The passive mixer down-converts the signals to the intermediate frequency (IF) band and conveys the signals to the analogue blocks. The local oscillator (LO) buffer divides the output frequency of the voltage controlled oscillator (VCO) and generates 25%-duty-cycle quadrature square waves to drive the mixer. Our measurement results display that the implemented RF front end achieves good overall performance while consuming only 6.7 mA from 1.2 V supply. The input return loss is better than -26 dB and the ultra low noise figure of 1.43 dB leads to high sensitivity of the GNSS receiver. The input 1 dB compression point is -43 dBm at the high gain of 48 dB. The designed circuit is fabricated in 55 nm CMOS technology and the die area, which is much smaller than traditional circuit, is around 220 × 280 μm2.

Multi-lane Changing Model with Coupling Driving Intention and Inclination

Directory of Open Access Journals (Sweden)

Jiangfeng Wang

2017-04-01

Full Text Available Considering the impact of drivers’ psychology and behaviour, a multi-lane changing model coupling driving intention and inclination is proposed by introducing two quantitative indices of intention: strength of lane changing and risk factor. According to the psychological and behavioural characteristics of aggressive drivers and conservative drivers, the safety conditions for lane changing are designed respectively. The numerical simulations show that the proposed model is suitable for describing the traffic flow with frequent lane changing, which is more consistent with the driving behaviour of drivers in China. Compared with symmetric two-lane cellular automata (STCA model, the proposed model can improve the average speed of vehicles by 1.04% under different traffic demands when aggressive drivers are in a higher proportion (the threshold of risk factor is 0.4. When the risk factor increases, the average speed shows the polarization phenomenon with the average speed slowing down in big traffic demand. The proposed model can reflect the relationship among density, flow, and speed, and the risk factor has a significant impact on density and flow.

Multi-Rate Acquisition for Dead Time Reduction in Magnetic Resonance Receivers: Application to Imaging With Zero Echo Time.

Science.gov (United States)

Marjanovic, Josip; Weiger, Markus; Reber, Jonas; Brunner, David O; Dietrich, Benjamin E; Wilm, Bertram J; Froidevaux, Romain; Pruessmann, Klaas P

2018-02-01

For magnetic resonance imaging of tissues with very short transverse relaxation times, radio-frequency excitation must be immediately followed by data acquisition with fast spatial encoding. In zero-echo-time (ZTE) imaging, excitation is performed while the readout gradient is already on, causing data loss due to an initial dead time. One major dead time contribution is the settling time of the filters involved in signal down-conversion. In this paper, a multi-rate acquisition scheme is proposed to minimize dead time due to filtering. Short filters and high output bandwidth are used initially to minimize settling time. With increasing time since the signal onset, longer filters with better frequency selectivity enable stronger signal decimation. In this way, significant dead time reduction is accomplished at only a slight increase in the overall amount of output data. Multi-rate acquisition was implemented with a two-stage filter cascade in a digital receiver based on a field-programmable gate array. In ZTE imaging in a phantom and in vivo, dead time reduction by multi-rate acquisition is shown to improve image quality and expand the feasible bandwidth while increasing the amount of data collected by only a few percent.

String vacuum backgrounds with covariantly constant null Killing vector and two-dimensional quantum gravity

International Nuclear Information System (INIS)

Tseytlin, A.A.

1993-01-01

We consider a two-dimensional sigma model with a (2+N)-dimensional Minkowski signature target space metric having a covariantly constant null Killing vector. We study solutions of the conformal invariance conditions in 2+N dimensions and find that generic solutions can be represented in terms of the RG flow in N-dimensional 'transverse space' theory. The resulting conformal invariant sigma model is interpreted as a quantum action of the two-dimensional scalar ('dilaton') quantum gravity model coupled to a (non-conformal) 'transverse' sigma model. The conformal factor of the two-dimensional metric is identified with a light-cone coordinate of the (2+N)-dimensional sigma model. We also discuss the case when the transverse theory is conformal (with or without the antisymmetric tensor background) and reproduce in a systematic way the solutions with flat transverse space known before. (orig.)

Average and extreme multi-atom Van der Waals interactions: Strong coupling of multi-atom Van der Waals interactions with covalent bonding

Directory of Open Access Journals (Sweden)

Finkelstein Alexei V

2007-07-01

Full Text Available Abstract Background The prediction of ligand binding or protein structure requires very accurate force field potentials – even small errors in force field potentials can make a 'wrong' structure (from the billions possible more stable than the single, 'correct' one. However, despite huge efforts to optimize them, currently-used all-atom force fields are still not able, in a vast majority of cases, even to keep a protein molecule in its native conformation in the course of molecular dynamics simulations or to bring an approximate, homology-based model of protein structure closer to its native conformation. Results A strict analysis shows that a specific coupling of multi-atom Van der Waals interactions with covalent bonding can, in extreme cases, increase (or decrease the interaction energy by about 20–40% at certain angles between the direction of interaction and the covalent bond. It is also shown that on average multi-body effects decrease the total Van der Waals energy in proportion to the square root of the electronic component of dielectric permittivity corresponding to dipole-dipole interactions at small distances, where Van der Waals interactions take place. Conclusion The study shows that currently-ignored multi-atom Van der Waals interactions can, in certain instances, lead to significant energy effects, comparable to those caused by the replacement of atoms (for instance, C by N in conventional pairwise Van der Waals interactions.

Fully coupled fluid-structure interaction model of reed valves in a multi-cylinder reciprocating piston compressor

Science.gov (United States)

Xie, F.; Nieter, J.; Lifson, A.; Reba, R.; Sishtla, V.

2017-08-01

For years compressor researchers have tried to account for the fluid interaction effect of the working fluid on valve motion in displacement compressors. In recent years, the computing capacities and available CFD and FEA programs have allowed fully coupled interaction of fluids and moving structures to be modelled more comprehensively. This paper describes our experience and results from developing a model of a multi-cylinder reciprocating piston compressor with suction and discharge valve systems that are fully coupled with the pressure pulsation in the adjacent plenum. Valve dynamics are captured by the model that affects compressor performance. The results show that higher running speed causes more discharge valve delay on closing due to higher pressure pulsation in discharge plenum. The acoustic property of the discharge plenum as it relates to valve motion is studied by the developed cost-effective standalone model.

Covariant quantum mechanics on a null plane

International Nuclear Information System (INIS)

Leutwyler, H.; Stern, J.

1977-03-01

Lorentz invariance implies that the null plane wave functions factorize into a kinematical part describing the motion of the system as a whole and an inner wave function that involves the specific dynamical properties of the system - in complete correspondence with the non-relativistic situation. Covariance is equivalent to an angular condition which admits non-trivial solutions

Chemical shift-dependent apparent scalar couplings: An alternative concept of chemical shift monitoring in multi-dimensional NMR experiments

International Nuclear Information System (INIS)

Kwiatkowski, Witek; Riek, Roland

2003-01-01

The paper presents an alternative technique for chemical shift monitoring in a multi-dimensional NMR experiment. The monitored chemical shift is coded in the line-shape of a cross-peak through an apparent residual scalar coupling active during an established evolution period or acquisition. The size of the apparent scalar coupling is manipulated with an off-resonance radio-frequency pulse in order to correlate the size of the coupling with the position of the additional chemical shift. The strength of this concept is that chemical shift information is added without an additional evolution period and accompanying polarization transfer periods. This concept was incorporated into the three-dimensional triple-resonance experiment HNCA, adding the information of 1 H α chemical shifts. The experiment is called HNCA coded HA, since the chemical shift of 1 H α is coded in the line-shape of the cross-peak along the 13 C α dimension

37 GHz Direct-Modulation Bandwidth of Multi-Section InGaAsP/InP DBR-Laser with weakly coupled active grating section

DEFF Research Database (Denmark)

Kaiser, W.; Bach, L.; Reithmaier, J. P.

2003-01-01

37 GHz direct-modulation bandwidth could be obtained by a multi-section design with an integrated weakly coupled DBR grating. The laser shows side mode suppression ratios of 45 dB and output powers exceeding 20 mW....

Multi-elemental analysis of aqueous geological samples by inductively coupled plasma-optical emission spectrometry

Science.gov (United States)

Todorov, Todor I.; Wolf, Ruth E.; Adams, Monique

2014-01-01

Typically, 27 major, minor, and trace elements are determined in natural waters, acid mine drainage, extraction fluids, and leachates of geological and environmental samples by inductively coupled plasma-optical emission spectrometry (ICP-OES). At the discretion of the analyst, additional elements may be determined after suitable method modifications and performance data are established. Samples are preserved in 1–2 percent nitric acid (HNO3) at sample collection or as soon as possible after collection. The aqueous samples are aspirated into the ICP-OES discharge, where the elemental emission signals are measured simultaneously for 27 elements. Calibration is performed with a series of matrix-matched, multi-element solution standards.

Vacuum Nuller Testbed Performance, Characterization and Null Control

Science.gov (United States)

Lyon, R. G.; Clampin, M.; Petrone, P.; Mallik, U.; Madison, T.; Bolcar, M.; Noecker, C.; Kendrick, S.; Helmbrecht, M. A.

2011-01-01

The Visible Nulling Coronagraph (VNC) can detect and characterize exoplanets with filled, segmented and sparse aperture telescopes, thereby spanning the choice of future internal coronagraph exoplanet missions. NASA/Goddard Space Flight Center (GSFC) has developed a Vacuum Nuller Testbed (VNT) to advance this approach, and assess and advance technologies needed to realize a VNC as a flight instrument. The VNT is an ultra-stable testbed operating at 15 Hz in vacuum. It consists of a MachZehnder nulling interferometer; modified with a "W" configuration to accommodate a hexpacked MEMS based deformable mirror (DM), coherent fiber bundle and achromatic phase shifters. The 2-output channels are imaged with a vacuum photon counting camera and conventional camera. Error-sensing and feedback to DM and delay line with control algorithms are implemented in a real-time architecture. The inherent advantage of the VNC is that it is its own interferometer and directly controls its errors by exploiting images from bright and dark channels simultaneously. Conservation of energy requires the sum total of the photon counts be conserved independent of the VNC state. Thus sensing and control bandwidth is limited by the target stars throughput, with the net effect that the higher bandwidth offloads stressing stability tolerances within the telescope. We report our recent progress with the VNT towards achieving an incremental sequence of contrast milestones of 10(exp 8) , 10(exp 9) and 10(exp 10) respectively at inner working angles approaching 2A/D. Discussed will be the optics, lab results, technologies, and null control. Shown will be evidence that the milestones have been achieved.

Collapse and bounce of null fluids

OpenAIRE

Creelman, Bradley; Booth, Ivan

2016-01-01

Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inwards even when non-gravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this p...

Null balance type electrostatic generating voltmeters

International Nuclear Information System (INIS)

Mahant, A.K.; Sidhu, N.P.S.; Gupta, U.C.

1977-01-01

A description is given of a null balance type generating voltmeter for measuring high D.C. voltage upto about 400 kV. The paper discusses the principle of operation, design, calibration and performance of the instrument. Main advantages of the device are: (1) it does not load the high voltage source, (2) no physical connection is required with the H.T. terminal and (3) calibration is independent of the rotor's frequency and amplifier's gain. (author)

Tightly-Coupled Integration of Multi-GNSS Single-Frequency RTK and MEMS-IMU for Enhanced Positioning Performance.

Science.gov (United States)

Li, Tuan; Zhang, Hongping; Niu, Xiaoji; Gao, Zhouzheng

2017-10-27

Dual-frequency Global Positioning System (GPS) Real-time Kinematics (RTK) has been proven in the past few years to be a reliable and efficient technique to obtain high accuracy positioning. However, there are still challenges for GPS single-frequency RTK, such as low reliability and ambiguity resolution (AR) success rate, especially in kinematic environments. Recently, multi-Global Navigation Satellite System (multi-GNSS) has been applied to enhance the RTK performance in terms of availability and reliability of AR. In order to further enhance the multi-GNSS single-frequency RTK performance in terms of reliability, continuity and accuracy, a low-cost micro-electro-mechanical system (MEMS) inertial measurement unit (IMU) is adopted in this contribution. We tightly integrate the single-frequency GPS/BeiDou/GLONASS and MEMS-IMU through the extended Kalman filter (EKF), which directly fuses the ambiguity-fixed double-differenced (DD) carrier phase observables and IMU data. A field vehicular test was carried out to evaluate the impacts of the multi-GNSS and IMU on the AR and positioning performance in different system configurations. Test results indicate that the empirical success rate of single-epoch AR for the tightly-coupled single-frequency multi-GNSS RTK/INS integration is over 99% even at an elevation cut-off angle of 40°, and the corresponding position time series is much more stable in comparison with the GPS solution. Besides, GNSS outage simulations show that continuous positioning with certain accuracy is possible due to the INS bridging capability when GNSS positioning is not available.

Zero emission city. Preliminary study; Null-Emissions-Stadt. Sondierungsstudie

Energy Technology Data Exchange (ETDEWEB)

Diefenbach, N.; Enseling, A.; Werner, P.; Flade, A.; Greiff, R.; Hennings, D.; Muehlich, E.; Wullkopf, U.; Sturm, P.; Kieslich, W.; Born, R.; Grossklos, M.; Hatteh, R.; Mueller, K.; Ratschow, A.; Valouch-Fornoff, C.

2002-10-01

The idea of a 'zero emission city' is investigated by the Institut Wohnen und Umwelt on behalf of the Federal Minister of Education and Research. After describing the current situation and defining the key parameters of a 'zero emission city', settlement structures, power supply, production processes and transportation are analyzed and linked with the communal action level to obtain a framework for research, activities and actions. The study ends with recommendations for a research programme 'zero emission city'. (orig.) [German] Die von den Staedten der Industrielaender ausgehenden Emissionen stellen im Hinblick auf die globalen Belastungen wie z.B. Treibhauseffekt, Ozonabbau und Versauerung das Hauptproblem dar. Aus diesem Grunde bietet es sich an, den Gedanken der 'Null-Emissions-Stadt', der Vision einer moeglichst emissionsfreien Stadt, aufzugreifen und auf seine Tragfaehigkeit fuer innovative Handlungsmodelle forschungsstrategisch zu ueberpruefen. Das Bundesministerium fuer Bildung und Forschung hat das Institut Wohnen und Umwelt beauftragt, in einer Sondierungsstudie dieser Fragestellung nachzugehen. Nach der Festlegung der Ausgangsbedingungen und Eckpunkte der Vision 'Null-Emissions-Stadt' und der Analyse der vier Handlungsfelder Siedlungsstrukturen, Energieversorgung, Produktionsprozesse (Kreislaufwirtschaft) und Verkehr werden diese aufgegriffen und mit der kommunalen Handlungsebene verknuepft und zu einem Forschungs-, Handlungs- und moeglichen Aktionsrahmen zusammengefuegt. Die Studie schliesst mit Hinweisen fuer die Gestaltung eines Forschungsprogramms 'Null-Emissions-Stadt'. (orig.)

A Model of Oxidative Stress Management: Moderation of Carbohydrate Metabolizing Enzymes in SOD1-Null Drosophila melanogaster

Science.gov (United States)

Bernard, Kristine E.; Parkes, Tony L.; Merritt, Thomas J. S.

2011-01-01

The response to oxidative stress involves numerous genes and mutations in these genes often manifest in pleiotropic ways that presumably reflect perturbations in ROS-mediated physiology. The Drosophila melanogaster SOD1-null allele (cSODn108) is proposed to result in oxidative stress by preventing superoxide breakdown. In SOD1-null flies, oxidative stress management is thought to be reliant on the glutathione-dependent antioxidants that utilize NADPH to cycle between reduced and oxidized form. Previous studies suggest that SOD1-null Drosophila rely on lipid catabolism for energy rather than carbohydrate metabolism. We tested these connections by comparing the activity of carbohydrate metabolizing enzymes, lipid and triglyceride concentration, and steady state NADPH:NADP+ in SOD1-null and control transgenic rescue flies. We find a negative shift in the activity of carbohydrate metabolizing enzymes in SOD1-nulls and the NADP+-reducing enzymes were found to have significantly lower activity than the other enzymes assayed. Little evidence for the catabolism of lipids as preferential energy source was found, as the concentration of lipids and triglycerides were not significantly lower in SOD1-nulls compared with controls. Using a starvation assay to impact lipids and triglycerides, we found that lipids were indeed depleted in both genotypes when under starvation stress, suggesting that oxidative damage was not preventing the catabolism of lipids in SOD1-null flies. Remarkably, SOD1-nulls were also found to be relatively resistant to starvation. Age profiles of enzyme activity, triglyceride and lipid concentration indicates that the trends observed are consistent over the average lifespan of the SOD1-nulls. Based on our results, we propose a model of physiological response in which organisms under oxidative stress limit the production of ROS through the down-regulation of carbohydrate metabolism in order to moderate the products exiting the electron transport chain. PMID

Vlasov Fluid stability of a 2-D plasma with a linear magnetic field null

International Nuclear Information System (INIS)

Kim, J.S.

1984-01-01

Vlasov Fluid stability of a 2-dimensional plasma near an O type magnetic null is investigated. Specifically, an elongated Z-pinch is considered, and applied to Field Reversed Configurations at Los Alamos National Laboratory by making a cylindrical approximation of the compact torus. The orbits near an elliptical O type null are found to be very complicated; the orbits are large and some are stochastic. The kinetic corrections to magnetohydrodynamics (MHD) are investigated by evaluating the expectation values of the growth rates of a Vlasov Fluid dispersion functional by using a set of trial functions based on ideal MHD. The dispersion functional involves fluid parts and orbit dependent parts. The latter involves phase integral of two time correlations. The phase integral is replaced by the time integral both for the regular and for the stochastic orbits. Two trial functions are used; one has a large displacement near the null and the other away from the null

Land-Atmosphere Coupling in the Multi-Scale Modelling Framework

Science.gov (United States)

Kraus, P. M.; Denning, S.

2015-12-01

The Multi-Scale Modeling Framework (MMF), in which cloud-resolving models (CRMs) are embedded within general circulation model (GCM) gridcells to serve as the model's cloud parameterization, has offered a number of benefits to GCM simulations. The coupling of these cloud-resolving models directly to land surface model instances, rather than passing averaged atmospheric variables to a single instance of a land surface model, the logical next step in model development, has recently been accomplished. This new configuration offers conspicuous improvements to estimates of precipitation and canopy through-fall, but overall the model exhibits warm surface temperature biases and low productivity.This work presents modifications to a land-surface model that take advantage of the new multi-scale modeling framework, and accommodate the change in spatial scale from a typical GCM range of ~200 km to the CRM grid-scale of 4 km.A parameterization is introduced to apportion modeled surface radiation into direct-beam and diffuse components. The diffuse component is then distributed among the land-surface model instances within each GCM cell domain. This substantially reduces the number excessively low light values provided to the land-surface model when cloudy conditions are modeled in the CRM, associated with its 1-D radiation scheme. The small spatial scale of the CRM, ~4 km, as compared with the typical ~200 km GCM scale, provides much more realistic estimates of precipitation intensity, this permits the elimination of a model parameterization of canopy through-fall. However, runoff at such scales can no longer be considered as an immediate flow to the ocean. Allowing sub-surface water flow between land-surface instances within the GCM domain affords better realism and also reduces temperature and productivity biases.The MMF affords a number of opportunities to land-surface modelers, providing both the advantages of direct simulation at the 4 km scale and a much reduced

Null geodesics and embedding diagrams of the interior Schwarzschild--de Sitter spacetimes with uniform density

International Nuclear Information System (INIS)

Stuchlik, Zdenek; Hledik, Stanislav; Soltes, Jiri; Ostgaard, Erlend

2001-01-01

Null geodesics and embedding diagrams of central planes in the ordinary space geometry and the optical reference geometry of the interior Schwarzschild--de Sitter spacetimes with uniform density are studied. For completeness, both positive and negative values of the cosmological constant are considered. The null geodesics are restricted to the central planes of these spacetimes, and their properties can be reflected by an 'effective potential.' If the interior spacetime is extremely compact, the effective potential has a local maximum corresponding to a stable circular null geodesic around which bound null geodesics are concentrated. The upper limit on the size of the interior spacetimes containing bound null geodesics is R=3M, independently of the value of the cosmological constant. The embedding diagrams of the central planes of the ordinary geometry into three-dimensional Euclidean space are well defined for the complete interior of all spacetimes with a repulsive cosmological constant, but the planes cannot be embedded into the Euclidean space in the case of spacetimes with subcritical values of an attractive cosmological constant. On the other hand, the embedding diagrams of the optical geometry are well defined for all of the spacetimes, and the turning points of these diagrams correspond to the radii of the circular null geodesics. All the embedding diagrams, for both the ordinary and optical geometry, are smoothly matched to the corresponding embedding diagrams of the external vacuum Schwarzschild--de Sitter spacetimes

Nonparametric Regression Estimation for Multivariate Null Recurrent Processes

Directory of Open Access Journals (Sweden)

Biqing Cai

2015-04-01

Full Text Available This paper discusses nonparametric kernel regression with the regressor being a \\(d\\-dimensional \\(\\beta\\-null recurrent process in presence of conditional heteroscedasticity. We show that the mean function estimator is consistent with convergence rate \\(\\sqrt{n(Th^{d}}\\, where \\(n(T\\ is the number of regenerations for a \\(\\beta\\-null recurrent process and the limiting distribution (with proper normalization is normal. Furthermore, we show that the two-step estimator for the volatility function is consistent. The finite sample performance of the estimate is quite reasonable when the leave-one-out cross validation method is used for bandwidth selection. We apply the proposed method to study the relationship of Federal funds rate with 3-month and 5-year T-bill rates and discover the existence of nonlinearity of the relationship. Furthermore, the in-sample and out-of-sample performance of the nonparametric model is far better than the linear model.

Conversation, coupling and complexity

DEFF Research Database (Denmark)

Fusaroli, Riccardo; Abney, Drew; Bahrami, Bahador

We investigate the linguistic co-construction of interpersonal synergies. By applying a measure of coupling between complex systems to an experimentally elicited corpus of joint decision dialogues, we show that interlocutors’ linguistic behavior displays increasing signature of multi-scale coupling......, known as complexity matching, over the course of interaction. Furthermore, we show that stronger coupling corresponds with more effective interaction, as measured by collective task performance....

Asymptotic symmetries of Rindler space at the horizon and null infinity

International Nuclear Information System (INIS)

Chung, Hyeyoun

2010-01-01

We investigate the asymptotic symmetries of Rindler space at null infinity and at the event horizon using both systematic and ad hoc methods. We find that the approaches that yield infinite-dimensional asymptotic symmetry algebras in the case of anti-de Sitter and flat spaces only give a finite-dimensional algebra for Rindler space at null infinity. We calculate the charges corresponding to these symmetries and confirm that they are finite, conserved, and integrable, and that the algebra of charges gives a representation of the asymptotic symmetry algebra. We also use relaxed boundary conditions to find infinite-dimensional asymptotic symmetry algebras for Rindler space at null infinity and at the event horizon. We compute the charges corresponding to these symmetries and confirm that they are finite and integrable. We also determine sufficient conditions for the charges to be conserved on-shell, and for the charge algebra to give a representation of the asymptotic symmetry algebra. In all cases, we find that the central extension of the charge algebra is trivial.

Null Geodesic Congruences, Asymptotically-Flat Spacetimes and Their Physical Interpretation

Directory of Open Access Journals (Sweden)

Timothy M. Adamo

2009-09-01

Full Text Available A priori, there is nothing very special about shear-free or asymptotically shear-free null geodesic congruences. Surprisingly, however, they turn out to possess a large number of fascinating geometric properties and to be closely related, in the context of general relativity, to a variety of physically significant effects. It is the purpose of this paper to try to fully develop these issues. This work starts with a detailed exposition of the theory of shear-free and asymptotically shear-free null geodesic congruences, i.e., congruences with shear that vanishes at future conformal null infinity. A major portion of the exposition lies in the analysis of the space of regular shear-free and asymptotically shear-free null geodesic congruences. This analysis leads to the space of complex analytic curves in complex Minkowski space. They in turn play a dominant role in the applications. The applications center around the problem of extracting interior physical properties of an asymptotically-flat spacetime directly from the asymptotic gravitational (and Maxwell field itself, in analogy with the determination of total charge by an integral over the Maxwell field at infinity or the identification of the interior mass (and its loss by (Bondi’s integrals of the Weyl tensor, also at infinity. More specifically, we will see that the asymptotically shear-free congruences lead us to an asymptotic definition of the center-of-mass and its equations of motion. This includes a kinematic meaning, in terms of the center-of-mass motion, for the Bondi three-momentum. In addition, we obtain insights into intrinsic spin and, in general, angular momentum, including an angular-momentum–conservation law with well-defined flux terms. When a Maxwell field is present, the asymptotically shear-free congruences allow us to determine/define at infinity a center-of-charge world line and intrinsic magnetic dipole moment.

Null Geodesic Congruences, Asymptotically-Flat Spacetimes and Their Physical Interpretation

Directory of Open Access Journals (Sweden)

Timothy M. Adamo

2012-01-01

Full Text Available A priori, there is nothing very special about shear-free or asymptotically shear-free null geodesic congruences. Surprisingly, however, they turn out to possess a large number of fascinating geometric properties and to be closely related, in the context of general relativity, to a variety of physically significant effects. It is the purpose of this paper to try to fully develop these issues. This work starts with a detailed exposition of the theory of shear-free and asymptotically shear-free null geodesic congruences, i.e., congruences with shear that vanishes at future conformal null infinity. A major portion of the exposition lies in the analysis of the space of regular shear-free and asymptotically shear-free null geodesic congruences. This analysis leads to the space of complex analytic curves in an auxiliary four-complex dimensional space, H-space. They in turn play a dominant role in the applications. The applications center around the problem of extracting interior physical properties of an asymptotically-flat spacetime directly from the asymptotic gravitational (and Maxwell field itself, in analogy with the determination of total charge by an integral over the Maxwell field at infinity or the identification of the interior mass (and its loss by (Bondi's integrals of the Weyl tensor, also at infinity. More specifically, we will see that the asymptotically shear-free congruences lead us to an asymptotic definition of the center-of-mass and its equations of motion. This includes a kinematic meaning, in terms of the center-of-mass motion, for the Bondi three-momentum. In addition, we obtain insights into intrinsic spin and, in general, angular momentum, including an angular-momentum--conservation law with well-defined flux terms. When a Maxwell field is present, the asymptotically shear-free congruences allow us to determine/define at infinity a center-of-charge world line and intrinsic magnetic dipole moment.

Null Geodesic Congruences, Asymptotically-Flat Spacetimes and Their Physical Interpretation.

Science.gov (United States)

Adamo, Timothy M; Newman, Ezra T; Kozameh, Carlos

2012-01-01

A priori, there is nothing very special about shear-free or asymptotically shear-free null geodesic congruences. Surprisingly, however, they turn out to possess a large number of fascinating geometric properties and to be closely related, in the context of general relativity, to a variety of physically significant effects. It is the purpose of this paper to try to fully develop these issues. This work starts with a detailed exposition of the theory of shear-free and asymptotically shear-free null geodesic congruences, i.e., congruences with shear that vanishes at future conformal null infinity. A major portion of the exposition lies in the analysis of the space of regular shear-free and asymptotically shear-free null geodesic congruences. This analysis leads to the space of complex analytic curves in an auxiliary four-complex dimensional space, [Formula: see text]-space. They in turn play a dominant role in the applications. The applications center around the problem of extracting interior physical properties of an asymptotically-flat spacetime directly from the asymptotic gravitational (and Maxwell) field itself, in analogy with the determination of total charge by an integral over the Maxwell field at infinity or the identification of the interior mass (and its loss) by (Bondi's) integrals of the Weyl tensor, also at infinity. More specifically, we will see that the asymptotically shear-free congruences lead us to an asymptotic definition of the center-of-mass and its equations of motion. This includes a kinematic meaning, in terms of the center-of-mass motion, for the Bondi three-momentum. In addition, we obtain insights into intrinsic spin and, in general, angular momentum, including an angular-momentum-conservation law with well-defined flux terms. When a Maxwell field is present, the asymptotically shear-free congruences allow us to determine/define at infinity a center-of-charge world line and intrinsic magnetic dipole moment.

Bi-dimensional null model analysis of presence-absence binary matrices.

Science.gov (United States)

Strona, Giovanni; Ulrich, Werner; Gotelli, Nicholas J

2018-01-01

Comparing the structure of presence/absence (i.e., binary) matrices with those of randomized counterparts is a common practice in ecology. However, differences in the randomization procedures (null models) can affect the results of the comparisons, leading matrix structural patterns to appear either "random" or not. Subjectivity in the choice of one particular null model over another makes it often advisable to compare the results obtained using several different approaches. Yet, available algorithms to randomize binary matrices differ substantially in respect to the constraints they impose on the discrepancy between observed and randomized row and column marginal totals, which complicates the interpretation of contrasting patterns. This calls for new strategies both to explore intermediate scenarios of restrictiveness in-between extreme constraint assumptions, and to properly synthesize the resulting information. Here we introduce a new modeling framework based on a flexible matrix randomization algorithm (named the "Tuning Peg" algorithm) that addresses both issues. The algorithm consists of a modified swap procedure in which the discrepancy between the row and column marginal totals of the target matrix and those of its randomized counterpart can be "tuned" in a continuous way by two parameters (controlling, respectively, row and column discrepancy). We show how combining the Tuning Peg with a wise random walk procedure makes it possible to explore the complete null space embraced by existing algorithms. This exploration allows researchers to visualize matrix structural patterns in an innovative bi-dimensional landscape of significance/effect size. We demonstrate the rational and potential of our approach with a set of simulated and real matrices, showing how the simultaneous investigation of a comprehensive and continuous portion of the null space can be extremely informative, and possibly key to resolving longstanding debates in the analysis of ecological

Multi-fluid simulations of the coupled solar wind-magnetosphere-ionsphere system

Science.gov (United States)

Lyon, J.

2011-12-01

This paper will review recent work done with the multi-fluid version of the Lyon-Fedder-Mobarry (MF-LFM) global MHD simulation code. We will concentrate on O+ outflow from the ionosphere and its importance for magnetosphere-ionosphere (MI) coupling and also the importance of ionospheric conditions in determining the outflow. While the predominant method of coupling between the magnetosphere and ionosphere is electrodynamic, it has become apparent the mass flows from the ionosphere into the magnetosphere can have profound effects on both systems. The earliest models to attempt to incorporate this effect used very crude clouds of plasma near the Earth. The earliest MF-LFM results showed that depending on the details of the outflow - where, how much, how fast - very different magnetospheric responses could be found. Two approaches to causally driven models for the outflow have been developed for use in global simulations, the Polar Wind Outflow Model (PWOM), started at the Univ. of Michigan, and the model used by Bill Lotko and co-workers at Dartmouth. We will give a quick review of this model which is based on the empirical relation between outflow fluence and Poynting flux discovered by Strangeway. An additional factor used in this model is the precipitating flux of electrons, which is presumed to correlate with the scale height of the upwelling ions. parameters such as outflow speed and density are constrained by the total fluence. The effects of the outflow depend on the speed. Slower outflow tends to land in the inner magnetosphere increasing the strength of the ring current. Higher speed flow out in the tail. Using this model, simulations have shown that solar wind dynamic pressure has a profound effect on the amount of fluence. The most striking result has been the simulation of magnetospheric sawtooth events. We will discuss future directions for this research, emphasizing the need for better physical models for the outflow process and its coupling to the

Null-polygonal minimal surfaces in AdS4 from perturbed W minimal models

International Nuclear Information System (INIS)

Hatsuda, Yasuyuki; Ito, Katsushi; Satoh, Yuji

2012-11-01

We study the null-polygonal minimal surfaces in AdS 4 , which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4) 4 /U(1) n-5 generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS 3 case.

Slot-coupled CW standing wave accelerating cavity

Energy Technology Data Exchange (ETDEWEB)

Wang, Shaoheng; Rimmer, Robert; Wang, Haipeng

2017-05-16

A slot-coupled CW standing wave multi-cell accelerating cavity. To achieve high efficiency graded beta acceleration, each cell in the multi-cell cavity may include different cell lengths. Alternatively, to achieve high efficiency with acceleration for particles with beta equal to 1, each cell in the multi-cell cavity may include the same cell design. Coupling between the cells is achieved with a plurality of axially aligned kidney-shaped slots on the wall between cells. The slot-coupling method makes the design very compact. The shape of the cell, including the slots and the cone, are optimized to maximize the power efficiency and minimize the peak power density on the surface. The slots are non-resonant, thereby enabling shorter slots and less power loss.

Investigation of reflood models by coupling REFLA-1D and multi-loop system model

International Nuclear Information System (INIS)

Sugimoto, Jun; Murao, Yoshio

1983-09-01

A system analysis code REFLA-1DS was developed by coupling reflood analysis code REFLA-1D and a multi-loop primary system model. The reflood models in the code were investigated for the development of the integral system analysis code. The REFLA-1D, which was developed with the small scale reflood experiment at JAERI, consists of one-dimensional core model and a primary system model with a constant loop resistance. The multi-loop primary system model was developed with the Cylindrical Core Test Facility of JAERI's large scale reflood tests. The components modeled in the code are the upper plenum, the steam generator, the coolant pump, the ECC injection port, the downcomer and the broken cold leg nozzle. The coupling between the two models in REFLA-1DS is accomplished by applying the equivalent flow resistance calculated with the multiloop model to the REFLA-1D. The characteristics of the code is its simplicity of the system model and the solution method which enables the fast running and the easy reflood analysis for the further model development. A fairly good agreement was obtained with the results of the Cylindrical Core Test Facility for the calculated water levels in the downcomer, the core and the upper plenum. A qualitatively good agreement was obtained concerning the parametric effects of the system pressure, the ECC flow rate and the initial clad temperature. Needs for further code improvements of the models, however, were pointed out. These include the problem concerning the generation rate of the steam and water droplets in the core in an early period, the effect of the flow oscillation on the core cooling, the heat release from the downcomer wall, and the stable system calculation. (author)

Coupling analysis of energy conversion in multi-mode vibration structural control using a synchronized switch damping method

International Nuclear Information System (INIS)

Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Inman, Daniel

2012-01-01

Modal coupling is an important issue in the analysis and control of structural systems with multi-degrees of freedom (MDOF). In this paper, modal coupling induced by energy conversion in the structural control of an MDOF system using a synchronized switch damping method is investigated theoretically and validated numerically. In the analysis, it is supposed that the voltage on the piezoelectric actuator is switched at the displacement extrema of a given mode. Two types of coupling in energy conversion are considered. The first is whether the switching action based on one mode induces energy conversion of the other modes. The second is whether the vibration of one mode affects the energy conversion of the other modes. The results indicate that the modal coupling in energy conversion is very complicated. In most cases the switching action based on one mode does induce energy conversion of another mode, but the efficiency depends on the frequency ratio of the two modes. The vibration of one mode affects the energy conversion of another mode only when the frequency ratio of the two modes takes some special values. Discussions are also given on the potential application of the theoretical results in the design of an energy harvesting device. (paper)

An inductorless multi-mode RF front end for GNSS receiver in 55 nm CMOS

International Nuclear Information System (INIS)

Luo Yanbin; Ma Chengyan; Gan Yebing; Qian Min; Ye Tianchun

2015-01-01

An inductorless multi-mode RF front end for a global navigation satellite system (GNSS) receiver is presented. Unlike the traditional topology of a low noise amplifier (LNA), the inductorless current-mode noise-canceling LNA is applied in this design. The high-impedance-input radio frequency amplifier (RFA) further amplifies the GNSS signals and changes the single-end signal path into fully differential. The passive mixer down-converts the signals to the intermediate frequency (IF) band and conveys the signals to the analogue blocks. The local oscillator (LO) buffer divides the output frequency of the voltage controlled oscillator (VCO) and generates 25%-duty-cycle quadrature square waves to drive the mixer. Our measurement results display that the implemented RF front end achieves good overall performance while consuming only 6.7 mA from 1.2 V supply. The input return loss is better than −26 dB and the ultra low noise figure of 1.43 dB leads to high sensitivity of the GNSS receiver. The input 1 dB compression point is −43 dBm at the high gain of 48 dB. The designed circuit is fabricated in 55 nm CMOS technology and the die area, which is much smaller than traditional circuit, is around 220 × 280 μm 2 . (paper)

MULTI-GNSS RECEIVER FOR AEROSPACE NAVIGATION AND POSITIONING APPLICATIONS

Directory of Open Access Journals (Sweden)

T. R. Peres

2014-03-01

Full Text Available The upcoming Galileo system opens a wide range of new opportunities in the Global Navigation Satellite System (GNSS market. However, the characteristics of the future GNSS signals require the development of new GNSS receivers. In the frame of the REAGE project, DEIMOS and ISEL have developed a GNSS receiver targeted for aerospace applications, supporting current and future GPS L1 and Galileo E1 signals, based on commercial (or, in the furthest extent, industrial grade components. Although the REAGE project aimed at space applications, the REAGE receiver is also applicable to many terrestrial applications (ground or airborne, such as Georeferencing and Unmanned Aerial Vehicle (UAV navigation. This paper presents the architecture and features of the REAGE receiver, as well as some results of the validation campaign with GPS L1 and Galileo E1 signals.

Expression Profiling of Differentiating Emerin-Null Myogenic Progenitor Identifies Molecular Pathways Implicated in Their Impaired Differentiation

Directory of Open Access Journals (Sweden)

Ashvin Iyer

2017-10-01

Full Text Available Mutations in the gene encoding emerin cause Emery-Dreifuss muscular dystrophy (EDMD, a disorder causing progressive skeletal muscle wasting, irregular heart rhythms and contractures of major tendons. RNA sequencing was performed on differentiating wildtype and emerin-null myogenic progenitors to identify molecular pathways implicated in EDMD, 340 genes were uniquely differentially expressed during the transition from day 0 to day 1 in wildtype cells. 1605 genes were uniquely expressed in emerin-null cells; 1706 genes were shared among both wildtype and emerin-null cells. One thousand and forty-seven transcripts showed differential expression during the transition from day 1 to day 2. Four hundred and thirty-one transcripts showed altered expression in both wildtype and emerin-null cells. Two hundred and ninety-five transcripts were differentially expressed only in emerin-null cells and 321 transcripts were differentially expressed only in wildtype cells. DAVID, STRING and Ingenuity Pathway Analysis identified pathways implicated in impaired emerin-null differentiation, including cell signaling, cell cycle checkpoints, integrin signaling, YAP/TAZ signaling, stem cell differentiation, and multiple muscle development and myogenic differentiation pathways. Functional enrichment analysis showed biological functions associated with the growth of muscle tissue and myogenesis of skeletal muscle were inhibited. The large number of differentially expressed transcripts upon differentiation induction suggests emerin functions during transcriptional reprograming of progenitors to committed myoblasts.

The Many Null Distributions of Person Fit Indices.

Science.gov (United States)

Molenaar, Ivo W.; Hoijtink, Herbert

1990-01-01

Statistical properties of person fit indices are reviewed as indicators of the extent to which a person's score pattern is in agreement with a measurement model. Distribution of a fit index and ability-free fit evaluation are discussed. The null distribution was simulated for a test of 20 items. (SLD)

Stitching interferometry of high numerical aperture cylindrical optics without using a fringe-nulling routine.

Science.gov (United States)

Peng, Junzheng; Wang, Qingquan; Peng, Xiang; Yu, Yingjie

2015-11-01

Stitching interferometry is a common method for measuring the figure error of high numerical aperture optics. However, subaperture measurement usually requires a fringe-nulling routine, thus making the stitching procedure complex and time-consuming. The challenge when measuring a surface without a fringe-nulling routine is that the rays no longer perpendicularly hit the surface. This violation of the null-test condition can lead to high fringe density and introduce high-order misalignment aberrations into the measurement result. This paper demonstrates that the high-order misalignment aberrations can be characterized by low-order misalignment aberrations; then, an efficient method is proposed to separate the high-order misalignment aberrations from subaperture data. With the proposed method, the fringe-nulling routine is not required. Instead, the subaperture data is measured under a nonzero fringe pattern. Then, all possible misalignment aberrations are removed with the proposed method. Finally, the full aperture map is acquired by connecting all subaperture data together. Experimental results showing the feasibility of the proposed procedure are presented.

Stable C-band fiber laser with switchable multi-wavelength output using coupled microfiber Mach-Zehnder interferometer

Science.gov (United States)

Ahmad, H.; Jasim, A. A.

2017-07-01

A compact coupled microfiber Mach-Zehnder interferometer (CM-MZI) is proposed and experimentally demonstrated for C-band region multi-wavelength tuning and switching in a fiber laser. The CM-MZI is fabricated using a 9 μm single tapered silica optical microfiber fabricated by flame-drawing technique and exploits multi-mode interference to produce spatial mode beating and suppress mode competition of the homogeneous gain medium. The output wavelength spacing is immune to changes in the external environment, but can be changed from 1.5 nm to 1.4 nm by slightly modifying the path-length difference of the CM-MZI. The proposed laser is capable of generating single, dual, triple, quintuple, and sextuple stabilize wavelengths outputs over a range of more than 32 nm using polarization rotation (PR) and macro-bending. The lasers having a 3 dB line-width of less than ∼30 pm and peak-to-floor of about 55 dB at a pump power of 38 mW.

Measurement of guided mode wave vectors by analysis of the transfer matrix obtained with multi-emitters and multi-receivers in contact

Energy Technology Data Exchange (ETDEWEB)

Minonzio, Jean-Gabriel; Talmant, Maryline; Laugier, Pascal, E-mail: jean-gabriel.minonzio@upmc.fr [UPMC Univ Paris 06, UMR 7623, LIP, 15 rue de l' ecole de medecine F-75005, Paris (France)

2011-01-01

Different quantitative ultrasound techniques are currently developed for clinical assessment of human bone status. This paper is dedicated to axial transmission: emitters and receivers are linearly arranged on the same side of the skeletal site, preferentially the forearm. In several clinical studies, the signal velocity of the earliest temporal event has been shown to discriminate osteoporotic patients from healthy subjects. However, a multi parameter approach might be relevant to improve bone diagnosis and this be could be achieved by accurate measurement of guided waves wave vectors. For clinical purposes and easy access to the measurement site, the length probe is limited to about 10 mm. The limited number of acquisition scan points on such a short distance reduces the efficiency of conventional signal processing techniques, such as spatio-temporal Fourier transform. The performance of time-frequency techniques was shown to be moderate in other studies. Thus, optimised signal processing is a critical point for a reliable estimate of guided mode wave vectors. Toward this end, a technique, taking benefit of using both multiple emitters and multiple receivers, is proposed. The guided mode wave vectors are obtained using a projection in the singular vectors basis. Those are determined by the singular values decomposition of the transmission matrix between the two arrays at different frequencies. This technique enables us to recover accurately guided waves wave vectors for moderately large array.

Aeroelastic simulation of multi-MW wind turbines using a free vortex model coupled to a geometrically exact beam model

International Nuclear Information System (INIS)

Saverin, Joseph; Peukert, Juliane; Marten, David; Pechlivanoglou, George; Paschereit, Christian Oliver; Greenblatt, David

2016-01-01

The current paper investigates the aeroelastic modelling of large, flexible multi- MW wind turbine blades. Most current performance prediction tools make use of the Blade Element Momentum (BEM) model, based upon a number of simplifying assumptions that hold only under steady conditions. This is why a lifting line free vortex wake (LLFVW) algorithm is used here to accurately resolve unsteady wind turbine aerodynamics. A coupling to the structural analysis tool BeamDyn, based on geometrically exact beam theory, allows for time-resolved aeroelastic simulations with highly deflected blades including bend-twist, coupling. Predictions of blade loading and deformation for rigid and flexible blades are analysed with reference to different aerodynamic and structural approaches. The emergency shutdown procedure is chosen as an examplary design load case causing large deflections to place emphasis on the influence of structural coupling and demonstrate the necessity of high fidelity structural models. (paper)

One-loop effect of null-like cosmology's holographic dual super-Yang-Mills

International Nuclear Information System (INIS)

Lin, F.-L.; Tomino, Dan

2007-01-01

We calculate the 1-loop effect in super-Yang-Mills which preserves 1/4-supersymmetries and is holographically dual to the null-like cosmology with a big-bang singularity. Though the bosonic and fermionic spectra do not agree precisely, we do obtain vanishing 1-loop vacuum energy for generic warped plane-wave type backgrounds with a big-bang singularity. Moreover, we find that the cosmological 'constant' contributed either by bosons or fermions is time-dependent. The issues about the particle production of some background and about the UV structure are also commented. We argue that the effective higher derivative interactions are suppressed as long as the Fourier transform of the time-dependent coupling is UV-finite. Our result holds for scalar configurations that are BPS but with arbitrary time-dependence. This suggests the existence of non-renormalization theorem for such a new class of time-dependent theories. Altogether, it implies that such a super-Yang-Mills is scale-invariant, and that its dual bulk quantum gravity might behave regularly near the big bang

The Harm Done to Reproducibility by the Culture of Null Hypothesis Significance Testing.

Science.gov (United States)

Lash, Timothy L

2017-09-15

In the last few years, stakeholders in the scientific community have raised alarms about a perceived lack of reproducibility of scientific results. In reaction, guidelines for journals have been promulgated and grant applicants have been asked to address the rigor and reproducibility of their proposed projects. Neither solution addresses a primary culprit, which is the culture of null hypothesis significance testing that dominates statistical analysis and inference. In an innovative research enterprise, selection of results for further evaluation based on null hypothesis significance testing is doomed to yield a low proportion of reproducible results and a high proportion of effects that are initially overestimated. In addition, the culture of null hypothesis significance testing discourages quantitative adjustments to account for systematic errors and quantitative incorporation of prior information. These strategies would otherwise improve reproducibility and have not been previously proposed in the widely cited literature on this topic. Without discarding the culture of null hypothesis significance testing and implementing these alternative methods for statistical analysis and inference, all other strategies for improving reproducibility will yield marginal gains at best. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Calculation of null points in SPAIR, FLAIR, and STIR. Part 2. Application to pelvic diffusion-weighted imaging with SPAIR at 3T

International Nuclear Information System (INIS)

Kita, Miho; Kawano, Kazuhiro; Kometani, Katsuya; Kondo, Toshihiko; Shimamoto, Kazuhiro; Tanaka, Humihiro; Oda, Hideyuki; Kojima, Akihiro; Sato, Morio

2013-01-01

Diffusion-weighted imaging (DWI) requires adequate fat suppression because of its sensitivity to chemical shift artifacts, especially at 3 Tesla (T). We investigated the utility of calculating the inversion time of the null point (TI null ) in pelvic DWI with spectral attenuated inversion recovery (SPAIR) at 3 T for obtaining adequate fat suppression. Thirteen volunteers underwent pelvic SPAIR-DWI using various SPAIR inversion delay times (TI) at 5-ms intervals in the range of the calculated TI null ±25 ms. The degree of fat suppression was evaluated into 3 grades and was compared among the various SPAIR-TIs with the calculated TI null . In 65 cases of prostatic disease, we evaluated the ratio of adequate fat suppression obtained using the calculated TI null . We obtained adequate fat suppression in all 13 volunteers and in 61 (94%) of the 65 patients using the calculated TI null . Fat suppression was best when the calculated TI null was used (P null (P null increased. In conclusion, this method of calculating the TI null may be useful for obtaining adequate fat suppression for pelvic SPAIR-DWI at 3T. (author)

Multi-Directional Environmental Sensors

Science.gov (United States)

Manohara, Harish (Inventor); Del Castillo, Linda Y. (Inventor); Mojarradi, Mohammed M. (Inventor)

2016-01-01

Systems and methods in accordance with embodiments of the invention implement multi-directional environmental sensors. In one embodiment, a multi-directional environmental sensor includes: an inner conductive element that is substantially symmetrical about three orthogonal planes; an outer conductive element that is substantially symmetrical about three orthogonal planes; and a device that measures the electrical characteristics of the multi-directional environmental sensor, the device having a first terminal and a second terminal; where the inner conductive element is substantially enclosed within the outer conductive element; where the inner conductive element is electrically coupled to the first terminal of the device; and where the outer conductive element is electrically coupled to the second terminal of the device.

Segmented Aperture Interferometric Nulling Testbed (SAINT) II: component systems update

Science.gov (United States)

Hicks, Brian A.; Bolcar, Matthew R.; Helmbrecht, Michael A.; Petrone, Peter; Burke, Elliot; Corsetti, James; Dillon, Thomas; Lea, Andrew; Pellicori, Samuel; Sheets, Teresa; Shiri, Ron; Agolli, Jack; DeVries, John; Eberhardt, Andrew; McCabe, Tyler

2017-09-01

This work presents updates to the coronagraph and telescope components of the Segmented Aperture Interferometric Nulling Testbed (SAINT). The project pairs an actively-controlled macro-scale segmented mirror with the Visible Nulling Coronagraph (VNC) towards demonstrating capabilities for the future space observatories needed to directly detect and characterize a significant sample of Earth-sized worlds around nearby stars in the quest for identifying those which may be habitable and possibly harbor life. Efforts to improve the VNC wavefront control optics and mechanisms towards repeating narrowband results are described. A narrative is provided for the design of new optical components aimed at enabling broadband performance. Initial work with the hardware and software interface for controlling the segmented telescope mirror is also presented.

Biological couplings: Classification and characteristic rules

Institute of Scientific and Technical Information of China (English)

无

2009-01-01

The phenomena that biological functions originate from biological coupling are the important biological foundation of multiple bionics and the significant discoveries in the bionic fields. In this paper, the basic concepts related to biological coupling are introduced from the bionic viewpoint. Constitution, classification and characteristic rules of biological coupling are illuminated, the general modes of biological coupling studies are analyzed, and the prospects of multi-coupling bionics are predicted.

Separation of uranium and plutonium isotopes for measurement by multi collector inductively coupled plasma mass spectroscopy

International Nuclear Information System (INIS)

Martinelli, R.E.; Hamilton, T.F.; Kehl, S.R.; Williams, R.W.

2009-01-01

Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with 233 U and 242 Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA R column coupled to a UTEVA R column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of 234 U/ 235 U, 238 U/ 235 U, 236 U/ 235 U, and 240 Pu/ 239 Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment. (author)

FFT Based VLSI Digital One Bit Electronic Warfare Receiver

National Research Council Canada - National Science Library

Chien-In, Henry

1998-01-01

... (1 GHz) digital receiver designed for electronic warfare applications. The receiver can process two simultaneous signals and has the potential for fabrication on a single multi-chip module (MCM...

Integrable structures and the quantization of free null initial data for gravity

Science.gov (United States)

Fuchs, Andreas; Reisenberger, Michael P.

2017-09-01

Variables for constraint free null canonical vacuum general relativity are presented which have simple Poisson brackets that facilitate quantization. Free initial data for vacuum general relativity on a pair of intersecting null hypersurfaces has been known since the 1960s. These consist of the ‘main’ data which are set on the bulk of the two null hypersurfaces, and additional ‘surface’ data set only on their intersection 2-surface. More recently the complete set of Poisson brackets of such data has been obtained. However the complexity of these brackets is an obstacle to their quantization. Part of this difficulty may be overcome using methods from the treatment of cylindrically symmetric gravity. Specializing from general to cylindrically symmetric solutions changes the Poisson algebra of the null initial data surprisingly little, but cylindrically symmetric vacuum general relativity is an integrable system, making powerful tools available. Here a transformation is constructed at the cylindrically symmetric level which maps the main initial data to new data forming a Poisson algebra for which an exact deformation quantization is known. (Although an auxiliary condition on the data has been quantized only in the asymptotically flat case, and a suitable representation of the algebra of quantum data by operators on a Hilbert space has not yet been found.) The definition of the new main data generalizes naturally to arbitrary, symmetryless gravitational fields, with the Poisson brackets retaining their simplicity. The corresponding generalization of the quantization is however ambiguous and requires further analysis.

Percentiles of the null distribution of 2 maximum lod score tests.

Science.gov (United States)

Ulgen, Ayse; Yoo, Yun Joo; Gordon, Derek; Finch, Stephen J; Mendell, Nancy R

2004-01-01

We here consider the null distribution of the maximum lod score (LOD-M) obtained upon maximizing over transmission model parameters (penetrance values, dominance, and allele frequency) as well as the recombination fraction. Also considered is the lod score maximized over a fixed choice of genetic model parameters and recombination-fraction values set prior to the analysis (MMLS) as proposed by Hodge et al. The objective is to fit parametric distributions to MMLS and LOD-M. Our results are based on 3,600 simulations of samples of n = 100 nuclear families ascertained for having one affected member and at least one other sibling available for linkage analysis. Each null distribution is approximately a mixture p(2)(0) + (1 - p)(2)(v). The values of MMLS appear to fit the mixture 0.20(2)(0) + 0.80chi(2)(1.6). The mixture distribution 0.13(2)(0) + 0.87chi(2)(2.8). appears to describe the null distribution of LOD-M. From these results we derive a simple method for obtaining critical values of LOD-M and MMLS. Copyright 2004 S. Karger AG, Basel

Alfvén wave dynamics at the neighborhood of a 2.5D magnetic null-point

Science.gov (United States)

Sabri, S.; Vasheghani Farahani, S.; Ebadi, H.; Hosseinpour, M.; Fazel, Z.

2018-05-01

The aim of the present study is to highlight the energy transfer via the interaction of magnetohydrodynamic waves with a 2.5D magnetic null-point in a finite plasma-β regime of the solar corona. An initially symmetric Alfvén pulse at a specific distance from a magnetic null-point is kicked towards the isothermal null-point. A shock-capturing Godunov-type PLUTO code is used to solve the ideal magnetohydrodynamic set equations in the context of wave-plasma energy transfer. As the Alfvén wave propagates towards the magnetic null-point it experiences speed lowering which ends up in releasing energy along the separatrices. In this line owing to the Alfvén wave, a series of events take place that contribute towards coronal heating. Nonlinear induced waves are by products of the torsional Alfvén interaction with magnetic null-points. The energy of these induced waves which are fast magnetoacoustic (transverse) and slow magnetoacoustic (longitudinal) waves are supplied by the Alfvén wave. The nonlinearly induced density perturbations are proportional to the Alfvén wave energy loss. This supplies energy for the propagation of fast and slow magnetoacoustic waves, where in contrast to the fast wave the slow wave experiences a continuous energy increase. As such, the slow wave may transfer its energy to the medium at later times, maintaining a continuous heating mechanism at the neighborhood of a magnetic null-point.

Limit structure of future null infinity tangent-topology of the event horizon and gravitational wave tail

International Nuclear Information System (INIS)

Tomizawa, Shinya; Siino, Masaru

2006-01-01

We investigated the relation between the behaviour of gravitational waves at late time and the limit structure of future null infinity tangent which will determine the topology of the event horizon far in the future. In the present paper, we mainly consider a spacetime with two black holes. Although in most cases, the black holes coalesce and the event horizon is topologically a single sphere far in the future, there are several possibilities that the black holes never coalesce and such exact solutions as examples. In our formulation, the tangent vector of future null infinity is, under conformal embedding, related to the number of black holes far in the future through the Poincare-Hopf theorem. Under the conformal embedding, the topology of the event horizon far in the future will be affected by the geometrical structure of the future null infinity. In this paper, we relate the behaviour of Weyl curvature to this limit behaviour of the generator vector of the future null infinity. We show if Weyl curvature decays sufficiently slowly at late time in the neighbourhood of future null infinity, two black holes never coalesce

Maxwell, Yang-Mills, Weyl and eikonal fields defined by any null shear-free congruence

Science.gov (United States)

Kassandrov, Vladimir V.; Rizcallah, Joseph A.

We show that (specifically scaled) equations of shear-free null geodesic congruences on the Minkowski space-time possess intrinsic self-dual, restricted gauge and algebraic structures. The complex eikonal, Weyl 2-spinor, SL(2, ℂ) Yang-Mills and complex Maxwell fields, the latter produced by integer-valued electric charges (“elementary” for the Kerr-like congruences), can all be explicitly associated with any shear-free null geodesic congruence. Using twistor variables, we derive the general solution of the equations of the shear-free null geodesic congruence (as a modification of the Kerr theorem) and analyze the corresponding “particle-like” field distributions, with bounded singularities of the associated physical fields. These can be obtained in a straightforward algebraic way and exhibit nontrivial collective dynamics simulating physical interactions.

From GLC to double-null coordinates and illustration with static black holes

Energy Technology Data Exchange (ETDEWEB)

Nugier, Fabien, E-mail: fnugier@ntu.edu.tw [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taipei, 10617 Taiwan (China)

2016-09-01

We present a system of coordinates deriving directly from the so-called Geodesic Light-Cone (GLC) coordinates and made of two null scalars intersecting on a 2-dimensional sphere parameterized by two constant angles along geodesics. These coordinates are shown to be equivalent to the well-known double-null coordinates. As GLC, they present interesting properties for cosmology and astrophysics. We discuss this latter topic for static black holes, showing simple descriptions for the metric or particles and photons trajectories. We also briefly comment on the time of flight of ultra-relativistic particles.

Diversity-Multiplexing-Nulling Trade-Off Analysis of Multiuser MIMO System for Intercell Interference Coordination

Directory of Open Access Journals (Sweden)

Jinwoo Kim

2017-01-01

Full Text Available A fundamental performance trade-off of multicell multiuser multiple-input multiple-output (MU-MIMO systems is explored for achieving intercell and intracell interference-free conditions. In particular, we analyze the three-dimensional diversity-multiplexing-nulling trade-off (DMNT among the diversity order (i.e., the slope of the error performance curve, multiplexing order (i.e., the number of users that are simultaneously served by MU-MIMO, and nulling order (i.e., the number of users with zero interference in a victim cell. This trade-off quantifies the performance of MU-MIMO in terms of its diversity and multiplexing order, while nulling the intercell interference toward the victim cell in the neighbor. First, we design a precoding matrix to mitigate both intercell and intracell interference for a linear precoding-based MU-MIMO system. Then, the trade-off relationship is obtained by analyzing the distribution of the signal-to-noise ratio (SNR at the user terminals. Furthermore, we demonstrate how DMNT can be applied to estimate the long-term throughput for each mobile station, which allows for determining the optimal number of multiplexing order and throughput loss due to the interference nulling.

Null Lens Assembly for X-Ray Mirror Segments

Science.gov (United States)

Robinson, David W.

2011-01-01

A document discusses a null lens assembly that allows laser interferometry of 60 deg. slumped glass mirror segments used in x-ray mirrors. The assembly consists of four lenses in precise alignment to each other, with incorporated piezoelectric nanometer stepping actuators to position the lenses in six degrees of freedom for positioning relative to each other.

L1 Adaptive Control Augmentation System with Application to the X-29 Lateral/Directional Dynamics: A Multi-Input Multi-Output Approach

Science.gov (United States)

Griffin, Brian Joseph; Burken, John J.; Xargay, Enric

2010-01-01

This paper presents an L(sub 1) adaptive control augmentation system design for multi-input multi-output nonlinear systems in the presence of unmatched uncertainties which may exhibit significant cross-coupling effects. A piecewise continuous adaptive law is adopted and extended for applicability to multi-input multi-output systems that explicitly compensates for dynamic cross-coupling. In addition, explicit use of high-fidelity actuator models are added to the L1 architecture to reduce uncertainties in the system. The L(sub 1) multi-input multi-output adaptive control architecture is applied to the X-29 lateral/directional dynamics and results are evaluated against a similar single-input single-output design approach.

Euclidean null controllability of perturbed infinite delay systems with ...

African Journals Online (AJOL)

Euclidean null controllability of perturbed infinite delay systems with limited control. ... Open Access DOWNLOAD FULL TEXT ... The results are established by placing conditions on the perturbation function which guarantee that, if the linear control base system is completely Euclidean controllable, then the perturbed system ...

Magnetic Reconnection at a Three-dimensional Solar Null Point

DEFF Research Database (Denmark)

Frederiksen, Jacob Trier; Baumann, Gisela; Galsgaard, Klaus

2012-01-01

Using a specific solar null point reconnection case studied by Masson et al (2009; ApJ 700, 559) we investigate the dependence of the reconnection rate on boundary driving speed, numerical resolution, type of resistivity (constant or numerical), and assumed stratification (constant density or sol...

Orexin Receptor Antagonism Improves Sleep and Reduces Seizures in Kcna1-null Mice.

Science.gov (United States)

Roundtree, Harrison M; Simeone, Timothy A; Johnson, Chaz; Matthews, Stephanie A; Samson, Kaeli K; Simeone, Kristina A

2016-02-01

Comorbid sleep disorders occur in approximately one-third of people with epilepsy. Seizures and sleep disorders have an interdependent relationship where the occurrence of one can exacerbate the other. Orexin, a wake-promoting neuropeptide, is associated with sleep disorder symptoms. Here, we tested the hypothesis that orexin dysregulation plays a role in the comorbid sleep disorder symptoms in the Kcna1-null mouse model of temporal lobe epilepsy. Rest-activity was assessed using infrared beam actigraphy. Sleep architecture and seizures were assessed using continuous video-electroencephalography-electromyography recordings in Kcna1-null mice treated with vehicle or the dual orexin receptor antagonist, almorexant (100 mg/kg, intraperitoneally). Orexin levels in the lateral hypothalamus/perifornical region (LH/P) and hypothalamic pathology were assessed with immunohistochemistry and oxygen polarography. Kcna1-null mice have increased latency to rapid eye movement (REM) sleep onset, sleep fragmentation, and number of wake epochs. The numbers of REM and non-REM (NREM) sleep epochs are significantly reduced in Kcna1-null mice. Severe seizures propagate to the wake-promoting LH/P where injury is apparent (indicated by astrogliosis, blood-brain barrier permeability, and impaired mitochondrial function). The number of orexin-positive neurons is increased in the LH/P compared to wild-type LH/P. Treatment with a dual orexin receptor antagonist significantly increases the number and duration of NREM sleep epochs and reduces the latency to REM sleep onset. Further, almorexant treatment reduces the incidence of severe seizures and overall seizure burden. Interestingly, we report a significant positive correlation between latency to REM onset and seizure burden in Kcna1-null mice. Dual orexin receptor antagonists may be an effective sleeping aid in epilepsy, and warrants further study on their somnogenic and ant-seizure effects in other epilepsy models. © 2016 Associated

Regional and Large-Scale Climate Influences on Tree-Ring Reconstructed Null Zone Position in San Francisco Bay

Science.gov (United States)

Stahle, D.; Griffin, D.; Cleaveland, M.; Fye, F.; Meko, D.; Cayan, D.; Dettinger, M.; Redmond, K.

2007-05-01

A new network of 36 moisture sensitive tree-ring chronologies has been developed in and near the drainage basins of the Sacramento and San Joaquin Rivers. The network is based entirely on blue oak (Quercus douglasii), which is a California endemic found from the lower forest border up into the mixed conifer zone in the Coast Ranges, Sierra Nevada, and Cascades. These blue oak tree-ring chronologies are highly correlated with winter-spring precipitation totals, Sacramento and San Joaquin streamflow, and with seasonal variations in salinity and null zone position in San Francisco Bay. Null zone is the non-tidal bottom water location where density-driven salinity and river-driven freshwater currents balance (zero flow). It is the area of highest turbidity, water residence time, sediment accumulation, and net primary productivity in the estuary. Null zone position is measured by the distance from the Golden Gate of the 2 per mil bottom water isohaline and is primarily controlled by discharge from the Sacramento and San Joaquin Rivers (and ultimately by winter-spring precipitation). The location of the null zone is an estuarine habitat indicator, a policy variable used for ecosystem management, and can have a major impact on biological resources in the San Francisco estuary. Precipitation-sensitive blue oak chronologies can be used to estimate null zone position based on the strong biogeophysical interaction among terrestrial, aquatic, and estuarine ecosystems, orchestrated by precipitation. The null zone reconstruction is 626-years long and provides a unique long term perspective on the interannual to decadal variability of this important estuarine habitat indicator. Consecutive two-year droughts (or longer) allow the null zone to shrink into the confined upper reaches of Suisun Bay, causing a dramatic reduction in phytoplankton production and favoring colonization of the estuary by marine biota. The reconstruction indicates an approximate 10 year recurrence interval

Null-polygonal minimal surfaces in AdS{sub 4} from perturbed W minimal models

Energy Technology Data Exchange (ETDEWEB)

Hatsuda, Yasuyuki [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ito, Katsushi [Tokyo Institute of Technology (Japan). Dept. of Physics; Satoh, Yuji [Tsukuba Univ., Sakura, Ibaraki (Japan). Inst. of Physics

2012-11-15

We study the null-polygonal minimal surfaces in AdS{sub 4}, which correspond to the gluon scattering amplitudes/Wilson loops in N=4 super Yang-Mills theory at strong coupling. The area of the minimal surfaces with n cusps is characterized by the thermodynamic Bethe ansatz (TBA) integral equations or the Y-system of the homogeneous sine-Gordon model, which is regarded as the SU(n-4){sub 4}/U(1){sup n-5} generalized parafermion theory perturbed by the weight-zero adjoint operators. Based on the relation to the TBA systems of the perturbed W minimal models, we solve the TBA equations by using the conformal perturbation theory, and obtain the analytic expansion of the remainder function around the UV/regular-polygonal limit for n = 6 and 7. We compare the rescaled remainder function for n=6 with the two-loop one, to observe that they are close to each other similarly to the AdS{sub 3} case.

Novel Microstrip Patch Antennas with Frequency Agility, Polarization Reconfigurability, Dual Null Steering Capability and Phased Array Antenna with Beam Steering Performance

Science.gov (United States)

Babakhani, Behrouz

Nowadays the wireless communication technology is playing an important role in our daily life. People use wireless devices not only as a conventional communication device but also as tracking and navigation tool, web browsing tool, data storage and transfer tool and so for many other reasons. Based on the user demand, wireless communication engineers try to accommodate as many as possible wireless systems and applications in a single device and therefore, creates a multifunctional device. Antenna, as an integral part of any wireless communication systems, should also be evolved and adjusted with development of wireless transceiver systems. Therefore multifunctional antennas have been introduced to support and enhance the functionality on modern wireless systems. The main focus and contribution of this thesis is design of novel multifunctional microstrip antennas with frequency agility, polarization reconfigurablity, dual null steering capability and phased array antenna with beam steering performance. In this thesis, first, a wide bandwidth(1.10 GHz to 1.60 GHz) right-handed circularly polarized (RHCP) directional antenna for global positioning system (GPS) satellite receive application has been introduced which covers all the GPS bands starting from L1 to L5. This design consists of two crossed bow-tie dipole antennas fed with sequentially phase rotated feed network backed with an artificial high impedance surface (HIS) structure to generate high gain directional radiation patterns. This design shows good CP gain and axial ratio (AR) and wide beamwidth performance. Although this design has good radiation quality, the size and the weight can be reduced as future study. In the second design, a frequency agile antenna was developed which also covers the L-band (L1 to L5) satellite communication frequencies. This frequency agile antenna was designed and realized by new implementation of varactor diodes in the geometry of a circular patch antenna. Beside wide frequency

Relative controllability and null controllability of linear delay systems ...

African Journals Online (AJOL)

Necessary and sufficient conditions are established for the relative, absolute controllability and null controllability of the generalized linear delay system and its discrete prototype. The paper presents illuminating examples on previous controllability results by Manitius and Olbrot [7] and carries over the results of Onwuatu [8] ...

Local modular Hamiltonians from the quantum null energy condition

Science.gov (United States)

Koeller, Jason; Leichenauer, Stefan; Levine, Adam; Shahbazi-Moghaddam, Arvin

2018-03-01

The vacuum modular Hamiltonian K of the Rindler wedge in any relativistic quantum field theory is given by the boost generator. Here we investigate the modular Hamiltonian for more general half-spaces which are bounded by an arbitrary smooth cut of a null plane. We derive a formula for the second derivative of the modular Hamiltonian with respect to the coordinates of the cut which schematically reads K''=Tv v . This formula can be integrated twice to obtain a simple expression for the modular Hamiltonian. The result naturally generalizes the standard expression for the Rindler modular Hamiltonian to this larger class of regions. Our primary assumptions are the quantum null energy condition—an inequality between the second derivative of the von Neumann entropy of a region and the stress tensor—and its saturation in the vacuum for these regions. We discuss the validity of these assumptions in free theories and holographic theories to all orders in 1 /N .

Analytical solutions for coupling fractional partial differential equations with Dirichlet boundary conditions

Science.gov (United States)

Ding, Xiao-Li; Nieto, Juan J.

2017-11-01

In this paper, we consider the analytical solutions of coupling fractional partial differential equations (FPDEs) with Dirichlet boundary conditions on a finite domain. Firstly, the method of successive approximations is used to obtain the analytical solutions of coupling multi-term time fractional ordinary differential equations. Then, the technique of spectral representation of the fractional Laplacian operator is used to convert the coupling FPDEs to the coupling multi-term time fractional ordinary differential equations. By applying the obtained analytical solutions to the resulting multi-term time fractional ordinary differential equations, the desired analytical solutions of the coupling FPDEs are given. Our results are applied to derive the analytical solutions of some special cases to demonstrate their applicability.

A multi-mode multi-band RF receiver front-end for a TD-SCDMA/LTE/LTE-advanced in 0.18-μm CMOS process

International Nuclear Information System (INIS)

Guo Rui; Zhang Haiying

2012-01-01

A fully integrated multi-mode multi-band directed-conversion radio frequency (RF) receiver front-end for a TD-SCDMA/LTE/LTE-advanced is presented. The front-end employs direct-conversion design, and consists of two differential tunable low noise amplifiers (LNA), a quadrature mixer, and two intermediate frequency (IF) amplifiers. The two independent tunable LNAs are used to cover all the four frequency bands, achieving sufficient low noise and high gain performance with low power consumption. Switched capacitor arrays perform a resonant frequency point calibration for the LNAs. The two LNAs are combined at the driver stage of the mixer, which employs a folded double balanced Gilbert structure, and utilizes PMOS transistors as local oscillator (LO) switches to reduce flicker noise. The front-end has three gain modes to obtain a higher dynamic range. Frequency band selection and mode of configuration is realized by an on-chip serial peripheral interface (SPI) module. The front-end is fabricated in a TSMC 0.18-μm RF CMOS process and occupies an area of 1.3 mm 2 . The measured double-sideband (DSB) noise figure is below 3.5 dB and the conversion gain is over 43 dB at all of the frequency bands. The total current consumption is 31 mA from a 1.8-V supply. (semiconductor integrated circuits)

Inertia coupling analysis of a self-decoupled wheel force transducer under multi-axis acceleration fields.

Directory of Open Access Journals (Sweden)

Lihang Feng

Full Text Available Wheel force transducer (WFT, which measures the three-axis forces and three-axis torques applied to the wheel, is an important instrument in the vehicle testing field and has been extremely promoted by researchers with great interests. The transducer, however, is typically mounted on the wheel of a moving vehicle, especially on a high speed car, when abruptly accelerating or braking, the mass/inertia of the transducer/wheel itself will have an extra effect on the sensor response so that the inertia/mass loads will also be detected and coupled into the signal outputs. The effect which is considered to be inertia coupling problem will decrease the sensor accuracy. In this paper, the inertia coupling of a universal WFT under multi-axis accelerations is investigated. According to the self-decoupling approach of the WFT, inertia load distribution is solved based on the principle of equivalent mass and rotary inertia, thus then inertia impact can be identified with the theoretical derivation. The verification is achieved by FEM simulation and experimental tests. Results show that strains in simulation agree well with the theoretical derivation. The relationship between the applied acceleration and inertia load for both wheel force and moment is the approximate linear, respectively. All the relative errors are less than 5% which are within acceptable and the inertia loads have the maximum impact on the signal output about 1.5% in the measurement range.

Inertia coupling analysis of a self-decoupled wheel force transducer under multi-axis acceleration fields.

Science.gov (United States)

Feng, Lihang; Lin, Guoyu; Zhang, Weigong; Dai, Dong

2015-01-01

Wheel force transducer (WFT), which measures the three-axis forces and three-axis torques applied to the wheel, is an important instrument in the vehicle testing field and has been extremely promoted by researchers with great interests. The transducer, however, is typically mounted on the wheel of a moving vehicle, especially on a high speed car, when abruptly accelerating or braking, the mass/inertia of the transducer/wheel itself will have an extra effect on the sensor response so that the inertia/mass loads will also be detected and coupled into the signal outputs. The effect which is considered to be inertia coupling problem will decrease the sensor accuracy. In this paper, the inertia coupling of a universal WFT under multi-axis accelerations is investigated. According to the self-decoupling approach of the WFT, inertia load distribution is solved based on the principle of equivalent mass and rotary inertia, thus then inertia impact can be identified with the theoretical derivation. The verification is achieved by FEM simulation and experimental tests. Results show that strains in simulation agree well with the theoretical derivation. The relationship between the applied acceleration and inertia load for both wheel force and moment is the approximate linear, respectively. All the relative errors are less than 5% which are within acceptable and the inertia loads have the maximum impact on the signal output about 1.5% in the measurement range.

"Time sweet time": circadian characterization of galectin-1 null mice

Directory of Open Access Journals (Sweden)

Rabinovich Gabriel A

2010-04-01

Full Text Available Abstract Background Recent evidence suggests a two-way interaction between the immune and circadian systems. Circadian control of immune factors, as well as the effect of immunological variables on circadian rhythms, might be key elements in both physiological and pathological responses to the environment. Among these relevant factors, galectin-1 is a member of a family of evolutionarily-conserved glycan-binding proteins with both extracellular and intracellular effects, playing important roles in immune cell processes and inflammatory responses. Many of these actions have been studied through the use of mice with a null mutation in the galectin-1 (Lgals1 gene. To further analyze the role of endogenous galectin-1 in vivo, we aimed to characterize the circadian behavior of galectin-1 null (Lgals1-/- mice. Methods We analyzed wheel-running activity in light-dark conditions, constant darkness, phase responses to light pulses (LP at circadian time 15, and reentrainment to 6 hour shifts in light-dark schedule in wild-type (WT and Lgals1-/- mice. Results We found significant differences in free-running period, which was longer in mutant than in WT mice (24.02 vs 23.57 h, p alpha (14.88 vs. 12.35 circadian h, p Conclusions Given the effect of a null mutation on circadian period and entrainment, we indicate that galectin-1 could be involved in the regulation of murine circadian rhythmicity. This is the first study implicating galectin-1 in the mammalian circadian system.

Relative null controllability of linear systems with multiple delays in ...

African Journals Online (AJOL)

varying multiple delays in state and control are developed. If the uncontrolled system is uniformly asymptotically stable, and if the linear system is controllable, then the linear system is null controllable. Journal of the Nigerian Association of ...

In vivo time-gated diffuse correlation spectroscopy at quasi-null source-detector separation.

Science.gov (United States)

Pagliazzi, M; Sekar, S Konugolu Venkata; Di Sieno, L; Colombo, L; Durduran, T; Contini, D; Torricelli, A; Pifferi, A; Mora, A Dalla

2018-06-01

We demonstrate time domain diffuse correlation spectroscopy at quasi-null source-detector separation by using a fast time-gated single-photon avalanche diode without the need of time-tagging electronics. This approach allows for increased photon collection, simplified real-time instrumentation, and reduced probe dimensions. Depth discriminating, quasi-null distance measurement of blood flow in a human subject is presented. We envision the miniaturization and integration of matrices of optical sensors of increased spatial resolution and the enhancement of the contrast of local blood flow changes.

Abnormal nociception and opiate sensitivity of STOP null mice exhibiting elevated levels of the endogenous alkaloid morphine

Directory of Open Access Journals (Sweden)

Aunis Dominique

2010-12-01

Full Text Available Abstract Background- Mice deficient for the stable tubule only peptide (STOP display altered dopaminergic neurotransmission associated with severe behavioural defects including disorganized locomotor activity. Endogenous morphine, which is present in nervous tissues and synthesized from dopamine, may contribute to these behavioral alterations since it is thought to play a role in normal and pathological neurotransmission. Results- In this study, we showed that STOP null brain structures, including cortex, hippocampus, cerebellum and spinal cord, contain high endogenous morphine amounts. The presence of elevated levels of morphine was associated with the presence of a higher density of mu opioid receptor with a higher affinity for morphine in STOP null brains. Interestingly, STOP null mice exhibited significantly lower nociceptive thresholds to thermal and mechanical stimulations. They also had abnormal behavioural responses to the administration of exogenous morphine and naloxone. Low dose of morphine (1 mg/kg, i.p. produced a significant mechanical antinociception in STOP null mice whereas it has no effect on wild-type mice. High concentration of naloxone (1 mg/kg was pronociceptive for both mice strain, a lower concentration (0.1 mg/kg was found to increase the mean mechanical nociceptive threshold only in the case of STOP null mice. Conclusions- Together, our data show that STOP null mice displayed elevated levels of endogenous morphine, as well as an increase of morphine receptor affinity and density in brain. This was correlated with hypernociception and impaired pharmacological sensitivity to mu opioid receptor ligands.

Twisting null geodesic congruences and the Einstein-Maxwell equations

International Nuclear Information System (INIS)

Newman, Ezra T; Silva-Ortigoza, Gilberto

2006-01-01

In a recent article, we returned to the study of asymptotically flat solutions of the vacuum Einstein equations with a rather unconventional point of view. The essential observation in that work was that from a given asymptotically flat vacuum spacetime with a given Bondi shear, one can find a class of asymptotically shear-free (but, in general, twisting) null geodesic congruences where the class was uniquely given up to the arbitrary choice of a complex analytic 'worldline' in a four-dimensional complex space. By imitating certain terms in the Weyl tensor that are found in the algebraically special type II metrics, this complex worldline could be made unique and given-or assigned-the physical meaning as the complex centre of mass. Equations of motion for this case were found. The purpose of the present work is to extend those results to asymptotically flat solutions of the Einstein-Maxwell equations. Once again, in this case, we get a class of asymptotically shear-free null geodesic congruences depending on a complex worldline in the same four-dimensional complex space. However in this case there will be, in general, two distinct but uniquely chosen worldlines, one of which can be assigned as the complex centre of charge while the other could be called the complex centre of mass. Rather than investigating the situation where there are two distinct complex worldlines, we study instead the special degenerate case where the two worldlines coincide, i.e., where there is a single unique worldline. This mimics the case of algebraically special Einstein-Maxwell fields where the degenerate principle null vector of the Weyl tensor coincides with a Maxwell principle null vector. Again we obtain equations of motion for this worldline-but explicitly found here only in an approximation. Though there are ambiguities in assigning physical meaning to different terms it appears as if reliance on the Kerr and charged Kerr metrics and classical electromagnetic radiation theory helps

Non-equilibrium quantum dynamics of ultra-cold atomic mixtures: the multi-layer multi-configuration time-dependent Hartree method for bosons

International Nuclear Information System (INIS)

Krönke, Sven; Cao, Lushuai; Schmelcher, Peter; Vendrell, Oriol

2013-01-01

We develop and apply the multi-layer multi-configuration time-dependent Hartree method for bosons, which represents an ab initio method for investigating the non-equilibrium quantum dynamics of multi-species bosonic systems. Its multi-layer feature allows for tailoring the wave function ansatz to describe intra- and inter-species correlations accurately and efficiently. To demonstrate the beneficial scaling and efficiency of the method, we explored the correlated tunneling dynamics of two species with repulsive intra- and inter-species interactions, to which a third species with vanishing intra-species interaction was weakly coupled. The population imbalances of the first two species can feature a temporal equilibration and their time evolution significantly depends on the coupling to the third species. Bosons of the first and second species exhibit a bunching tendency, whose strength can be influenced by their coupling to the third species. (paper)

Coupling of THALES and FROST using MPI Method

International Nuclear Information System (INIS)

Park, Jin Woo; Ryu, Seok Hee; Jung, Chan Do; Jung, Jee Hoon; Um, Kil Sup; Lee, Jae Il

2013-01-01

This paper presents the coupling method between THALES and FROST and the simulation results with the coupled code system. In this study, subchannel analysis code THALES and transient fuel performance code FROST were coupled using MPI method as the first stage of the development of the multi-dimensional safety analysis methodology. As a part of the validation, the CEA ejection accident was simulated using the coupled THALES-FROST code and the results were compared with the ShinKori 3 and 4 FSAR. Comparison results revealed that CHASER using MPI method predicts fuel temperatures and heat flux quantitatively well. Thus it was confirmed that the THALES and FROST are properly coupled. In near future, ASTRA, multi-dimensional core neutron kinetics code, will be linked to THALESFROST code for the detailed three-dimensional CEA ejection analysis. The current safety analysis methodology for a CEA ejection accident based on numerous conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KNF is developing the multi-dimensional safety analysis methodology to enhance the consequences of the CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, subchannel analysis code THALES, and transient fuel performance analysis code FROST are being coupled using message passing interface(MPI). For the first step, THALES and FROST are coupled and tested

Design and simulation of a planar micro-optic free-space receiver

Science.gov (United States)

Nadler, Brett R.; Hallas, Justin M.; Karp, Jason H.; Ford, Joseph E.

2017-11-01

We propose a compact directional optical receiver for free-space communications, where a microlens array and micro-optic structures selectively couple light from a narrow incidence angle into a thin slab waveguide and then to an edge-mounted detector. A small lateral translation of the lenslet array controls the coupled input angle, enabling the receiver to select the transmitter source direction. We present the optical design and simulation of a 10mm x 10mm aperture receiver using a 30μm thick silicon waveguide able to couple up to 2.5Gbps modulated input to a 10mm x 30μm wide detector.

Multi-kW high-brightness fiber coupled diode laser based on two dimensional stacked tailored diode bars

Science.gov (United States)

Bayer, Andreas; Unger, Andreas; Köhler, Bernd; Küster, Matthias; Dürsch, Sascha; Kissel, Heiko; Irwin, David A.; Bodem, Christian; Plappert, Nora; Kersten, Maik; Biesenbach, Jens

2016-03-01

The demand for high brightness fiber coupled diode laser devices in the multi kW power region is mainly driven by industrial applications for materials processing, like brazing, cladding and metal welding, which require a beam quality better than 30 mm x mrad and power levels above 3kW. Reliability, modularity, and cost effectiveness are key factors for success in the market. We have developed a scalable and modular diode laser architecture that fulfills these requirements through use of a simple beam shaping concept based on two dimensional stacking of tailored diode bars mounted on specially designed, tap water cooled heat sinks. The base element of the concept is a tailored diode laser bar with an epitaxial and lateral structure designed such that the desired beam quality in slow-axis direction can be realized without using sophisticated beam shaping optics. The optical design concept is based on fast-axis collimator (FAC) and slow-axis collimator (SAC) lenses followed by only one additional focusing optic for efficient coupling into a 400 μm fiber with a numerical aperture (NA) of 0.12. To fulfill the requirements of scalability and modularity, four tailored bars are populated on a reduced size, tap water cooled heat sink. The diodes on these building blocks are collimated simply via FAC and SAC. The building blocks can be stacked vertically resulting in a two-dimensional diode stack, which enables a compact design of the laser source with minimum beam path length. For a single wavelength, up to eight of these building blocks, implying a total of 32 tailored bars, can be stacked into a submodule, polarization multiplexed, and coupled into a 400 μm, 0.12NA fiber. Scalability into the multi kW region is realized by wavelength combining of replaceable submodules in the spectral range from 900 - 1100 nm. We present results of a laser source based on this architecture with an output power of more than 4 kW and a beam quality of 25 mm x mrad.

Lovelock vacua with a recurrent null vector field

Czech Academy of Sciences Publication Activity Database

Ortaggio, Marcello

2018-01-01

Roč. 97, č. 4 (2018), č. článku 044051. ISSN 2470-0010 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : Lovelock gravity * recurrent null vector field Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.568, year: 2016 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.97.044051

Lovelock vacua with a recurrent null vector field

Czech Academy of Sciences Publication Activity Database

Ortaggio, Marcello

2018-01-01

Roč. 97, č. 4 (2018), č. článku 044051. ISSN 2470-0010 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : Lovelock gravity * recurrent null vector field Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.568, year: 2016 https://journals. aps .org/prd/abstract/10.1103/PhysRevD.97.044051

Globally Coupled Chaotic Maps with Constant Force

International Nuclear Information System (INIS)

Li Jinghui

2008-01-01

We investigate the motion of the globally coupled maps (logistic map) with a constant force. It is shown that the constant force can cause multi-synchronization for the globally coupled chaotic maps studied by us.

Coupling of system thermal–hydraulics and Monte-Carlo code: Convergence criteria and quantification of correlation between statistical uncertainty and coupled error

International Nuclear Information System (INIS)

Wu, Xu; Kozlowski, Tomasz

2015-01-01

Highlights: • Coupling of Monte Carlo code Serpent and thermal–hydraulics code RELAP5. • A convergence criterion is developed based on the statistical uncertainty of power. • Correlation between MC statistical uncertainty and coupled error is quantified. • Both UO 2 and MOX single assembly models are used in the coupled simulation. • Validation of coupling results with a multi-group transport code DeCART. - Abstract: Coupled multi-physics approach plays an important role in improving computational accuracy. Compared with deterministic neutronics codes, Monte Carlo codes have the advantage of a higher resolution level. In the present paper, a three-dimensional continuous-energy Monte Carlo reactor physics burnup calculation code, Serpent, is coupled with a thermal–hydraulics safety analysis code, RELAP5. The coupled Serpent/RELAP5 code capability is demonstrated by the improved axial power distribution of UO 2 and MOX single assembly models, based on the OECD-NEA/NRC PWR MOX/UO 2 Core Transient Benchmark. Comparisons of calculation results using the coupled code with those from the deterministic methods, specifically heterogeneous multi-group transport code DeCART, show that the coupling produces more precise results. A new convergence criterion for the coupled simulation is developed based on the statistical uncertainty in power distribution in the Monte Carlo code, rather than ad-hoc criteria used in previous research. The new convergence criterion is shown to be more rigorous, equally convenient to use but requiring a few more coupling steps to converge. Finally, the influence of Monte Carlo statistical uncertainty on the coupled error of power and thermal–hydraulics parameters is quantified. The results are presented such that they can be used to find the statistical uncertainty to use in Monte Carlo in order to achieve a desired precision in coupled simulation

Shaping Up the Practice of Null Hypothesis Significance Testing.

Science.gov (United States)

Wainer, Howard; Robinson, Daniel H.

2003-01-01

Discusses criticisms of null hypothesis significance testing (NHST), suggesting that historical use of NHST was reasonable, and current users should read Sir Ronald Fisher's applied work. Notes that modifications to NHST and interpretations of its outcomes might better suit the needs of modern science. Concludes that NHST is most often useful as…

Luxembourg in the Early Days of the EEC: Null Player or Not?

Directory of Open Access Journals (Sweden)

Alexander Mayer

2018-05-01

Full Text Available Voters whose yes-or-no decision never makes a difference to the outcome in a simple voting game are known as “null players”. Luxembourg’s role in the Council of Ministers during the first period of the European Economic Community (EEC is often cited as a real-world case. The paper contrasts the textbook claim that Luxembourg was a null player with a more comprehensive picture of Luxembourg’s role in EEC’s voting system. The assessment of Luxembourg’s voting power is sensitive to the role played by the European Commission in the decision-making procedure and the measurement concepts underlying power evaluations.

Increased Oocyte Degeneration and Follicular Atresia during the Estrous Cycle in Anti-Müllerian Hormone Null Mice

NARCIS (Netherlands)

Visser, Jenny A.; Durlinger, Alexandra L.L.; Peters, Isolde J.J.; Heuvel, Edwin R. van den; Rose, Ursula M.; Kramer, Piet; Jong, Frank H. de; Themmen, Axel P.N.

2007-01-01

Anti-Müllerian hormone (AMH) plays an important role in folliculogenesis. AMH null mice display an increased recruitment of primordial follicles. Nevertheless, these mice do not have proportionally more preovulatory follicles. Therefore, AMH null mice provide an interesting genetic model to study

Method for Measurement of Multi-Degrees-of-Freedom Motion Parameters Based on Polydimethylsiloxane Cross-Coupling Diffraction Gratings

Science.gov (United States)

Duan, Junping; Zhu, Qiang; Qian, Kun; Guo, Hao; Zhang, Binzhen

2017-08-01

This work presents a multi-degrees-of-freedom motion parameter measurement method based on the use of cross-coupling diffraction gratings that were prepared on the two sides of a polydimethylsiloxane (PDMS) substrate using oxygen plasma processing technology. The laser beam that travels pass the cross-coupling optical grating would be diffracted into a two-dimensional spot array. The displacement and the gap size of the spot-array were functions of the movement of the laser source, as explained by the Fraunhofer diffraction effect. A 480 × 640 pixel charge-coupled device (CCD) was used to acquire images of the two-dimensional spot-array in real time. A proposed algorithm was then used to obtain the motion parameters. Using this method and the CCD described above, the resolutions of the displacement and the deflection angle were 0.18 μm and 0.0075 rad, respectively. Additionally, a CCD with a higher pixel count could improve the resolutions of the displacement and the deflection angle to sub-nanometer and micro-radian scales, respectively. Finally, the dynamic positions of hovering rotorcraft have been tracked and checked using the proposed method, which can be used to correct the craft's position and provide a method for aircraft stabilization in the sky.

Urban Flow and Pollutant Dispersion Simulation with Multi-scale coupling of Meteorological Model with Computational Fluid Dynamic Analysis

Science.gov (United States)

Liu, Yushi; Poh, Hee Joo

2014-11-01

The Computational Fluid Dynamics analysis has become increasingly important in modern urban planning in order to create highly livable city. This paper presents a multi-scale modeling methodology which couples Weather Research and Forecasting (WRF) Model with open source CFD simulation tool, OpenFOAM. This coupling enables the simulation of the wind flow and pollutant dispersion in urban built-up area with high resolution mesh. In this methodology meso-scale model WRF provides the boundary condition for the micro-scale CFD model OpenFOAM. The advantage is that the realistic weather condition is taken into account in the CFD simulation and complexity of building layout can be handled with ease by meshing utility of OpenFOAM. The result is validated against the Joint Urban 2003 Tracer Field Tests in Oklahoma City and there is reasonably good agreement between the CFD simulation and field observation. The coupling of WRF- OpenFOAM provide urban planners with reliable environmental modeling tool in actual urban built-up area; and it can be further extended with consideration of future weather conditions for the scenario studies on climate change impact.

Multi-zone coupling productivity of horizontal well fracturing with complex fracture networks in shale gas reservoirs

Directory of Open Access Journals (Sweden)

Weiyao Zhu

2018-02-01

best. Therefore, it is necessary to control fracturing degree reasonably and optimize fracturing parameters, so as to provide a theoretical support for the optimization design of shale gas reservoir fracturing. Keywords: Shale gas, Reservoir, Fracturing, Horizontal well, Complex fracture network, Multi-zone coupling, Multi-scale, Interference, Productivity capacity

Improved noise-adding radiometer for microwave receivers

Science.gov (United States)

Batelaan, P. D.; Stelzried, C. T.; Goldstein, R. M.

1973-01-01

Use of input switch and noise reference standard is avoided by using noise-adding technique. Excess noise from solid state noise-diode is coupled into receiver through directional coupler and square-wave modulated at low rate. High sensitivity receivers for radioastronomy applications are utilized with greater confidence in stability of radiometer.

Shining LUX on isospin-violating dark matter beyond leading order

DEFF Research Database (Denmark)

Cirigliano, V.; Graesser, M. L.; Ovanesyan, G.

2014-01-01

Isospin-violating dark matter (IVDM) has been proposed as a viable scenario to reconcile conflicting positive and null results from direct detection dark matter experiments. We show that the lowest-order dark matter-nucleus scattering rate can receive large and nucleus-dependent corrections at next......-to-leading order (NLO) in the chiral expansion. The size of these corrections depends on the specific couplings of dark matter to quark flavors and gluons. In general the full NLO dark-matter-nucleus cross-section is not adequately described by just the zero-energy proton and neutron couplings. These statements...... are concretely illustrated in a scenario where the dark matter couples to quarks through scalar operators. We find the canonical IVDM scenario can reconcile the null XENON and LUX results and the recent CDMS-Si findings provided its couplings to second and third generation quarks either lie on a special line...

Pair of null gravitating shells: III. Algebra of Dirac's observables

International Nuclear Information System (INIS)

Kouletsis, I; Hajicek, P

2002-01-01

The study of the two-shell system started in 'pair of null gravitating shells I and II' is continued. The pull back of the Liouville form to the constraint surface, which contains complete information about the Poisson brackets of Dirac observables, is computed in the singular double-null Eddington-Finkelstein (DNEF) gauge. The resulting formula shows that the variables conjugate to the Schwarzschild masses of the intershell spacetimes are simple combinations of the values of the DNEF coordinates on these spacetimes at the shells. The formula is valid for any number of in- and outgoing shells. After applying it to the two-shell system, the symplectic form is calculated for each component of the physical phase space; regular coordinates are found, defining it as a symplectic manifold. The symplectic transformation between the initial and final values of observables for the shell-crossing case is given

Magnetic Nulls and Super-radial Expansion in the Solar Corona

Energy Technology Data Exchange (ETDEWEB)

Gibson, Sarah E.; Dalmasse, Kevin; Tomczyk, Steven; Toma, Giuliana de; Burkepile, Joan; Galloy, Michael [National Center for Atmospheric Research, 3080 Center Green Drive, Boulder, CO 80301 (United States); Rachmeler, Laurel A. [NASA Marshall Space Flight Center, Huntsville, AL 35811 (United States); Rosa, Marc L. De, E-mail: sgibson@ucar.edu [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street B/252, Palo Alto, CA 94304 (United States)

2017-05-10

Magnetic fields in the Sun’s outer atmosphere—the corona—control both solar-wind acceleration and the dynamics of solar eruptions. We present the first clear observational evidence of coronal magnetic nulls in off-limb linearly polarized observations of pseudostreamers, taken by the Coronal Multichannel Polarimeter (CoMP) telescope. These nulls represent regions where magnetic reconnection is likely to act as a catalyst for solar activity. CoMP linear-polarization observations also provide an independent, coronal proxy for magnetic expansion into the solar wind, a quantity often used to parameterize and predict the solar wind speed at Earth. We introduce a new method for explicitly calculating expansion factors from CoMP coronal linear-polarization observations, which does not require photospheric extrapolations. We conclude that linearly polarized light is a powerful new diagnostic of critical coronal magnetic topologies and the expanding magnetic flux tubes that channel the solar wind.

Dynamics of multi-frequency oscillator ensembles with resonant coupling

Science.gov (United States)

Lück, S.; Pikovsky, A.

2011-07-01

We study dynamics of populations of resonantly coupled oscillators having different frequencies. Starting from the coupled van der Pol equations we derive the Kuramoto-type phase model for the situation, where the natural frequencies of two interacting subpopulations are in relation 2:1. Depending on the parameter of coupling, ensembles can demonstrate fully synchronous clusters, partial synchrony (only one subpopulation synchronizes), or asynchrony in both subpopulations. Theoretical description of the dynamics based on the Watanabe-Strogatz approach is developed.

Testing non-minimally coupled inflation with CMB data: a Bayesian analysis

International Nuclear Information System (INIS)

Campista, Marcela; Benetti, Micol; Alcaniz, Jailson

2017-01-01

We use the most recent cosmic microwave background (CMB) data to perform a Bayesian statistical analysis and discuss the observational viability of inflationary models with a non-minimal coupling, ξ, between the inflaton field and the Ricci scalar. We particularize our analysis to two examples of small and large field inflationary models, namely, the Coleman-Weinberg and the chaotic quartic potentials. We find that ( i ) the ξ parameter is closely correlated with the primordial amplitude ; ( ii ) although improving the agreement with the CMB data in the r − n s plane, where r is the tensor-to-scalar ratio and n s the primordial spectral index, a non-null coupling is strongly disfavoured with respect to the minimally coupled standard ΛCDM model, since the upper bounds of the Bayes factor (odds) for ξ parameter are greater than 150:1.

Testing non-minimally coupled inflation with CMB data: a Bayesian analysis

Energy Technology Data Exchange (ETDEWEB)

Campista, Marcela; Benetti, Micol; Alcaniz, Jailson, E-mail: campista@on.br, E-mail: micolbenetti@on.br, E-mail: alcaniz@on.br [Observatório Nacional, Rua General José Cristino 77, Rio de Janeiro, RJ, 20921-400 Brazil (Brazil)

2017-09-01

We use the most recent cosmic microwave background (CMB) data to perform a Bayesian statistical analysis and discuss the observational viability of inflationary models with a non-minimal coupling, ξ, between the inflaton field and the Ricci scalar. We particularize our analysis to two examples of small and large field inflationary models, namely, the Coleman-Weinberg and the chaotic quartic potentials. We find that ( i ) the ξ parameter is closely correlated with the primordial amplitude ; ( ii ) although improving the agreement with the CMB data in the r − n {sub s} plane, where r is the tensor-to-scalar ratio and n {sub s} the primordial spectral index, a non-null coupling is strongly disfavoured with respect to the minimally coupled standard ΛCDM model, since the upper bounds of the Bayes factor (odds) for ξ parameter are greater than 150:1.

Null-plane formulation of Bethe-Salpeter qqq dynamics: Baryon mass spectra

International Nuclear Information System (INIS)

Kulshreshtha, D.S.; Mitra, A.N.

1988-01-01

The Bethe-Salpeter (BS) equation for a qqq system is formulated in the null-plane approximation (NPA) for the BS wave function, as a direct generalization of a corresponding QCD-motivated formalism developed earlier for qq-bar systems. The confinement kernel is assumed vector type (γ/sub μ//sup (1)/γ/sub μ//sup (2)/) for both qq-bar and qq pairs, with identical harmonic structures, and with the spring constant proportional, among other things, to the running coupling constant α/sub s/ (for an explicit QCD motivation). The harmonic kernel is given a suitable Lorentz-invariant definition [not D'Alembertian 2 δ 4 (q)], which is amenable to NPA reduction in a covariant form. The reduced qqq equation in NPA is solved algebraically in a six-dimensional harmonic-oscillator (HO) basis, using the techniques of SO(2,1) algebra interlinked with S 3 symmetry. The results on the nonstrange baryon mass spectra agree well with the data all the way up to N = 6, thus confirming the asymptotic prediction M∼N/sup 2/3/ characteristic of vector confinement in HO form. There are no extra parameters beyond the three basic constants (ω 0 ,C 0 ,m/sub u//sub d/) which were earlier found to provide excellent fits to meson spectra (qq-bar)

Altered extracellular matrix remodeling and angiogenesis in sponge granulomas of thrombospondin 2-null mice.

Science.gov (United States)

Kyriakides, T R; Zhu, Y H; Yang, Z; Huynh, G; Bornstein, P

2001-10-01

The matricellular angiogenesis inhibitor, thrombospondin (TSP) 2, has been shown to be an important modulator of wound healing and the foreign body response. Specifically, TSP2-null mice display improved healing with minimal scarring and form well-vascularized foreign body capsules. In this study we performed subcutaneous implantation of sponges and investigated the resulting angiogenic and fibrogenic responses. Histological and immunohistochemical analysis of sponges, excised at 7, 14, and 21 days after implantation, revealed significant differences between TSP2-null and wild-type mice. Most notably, TSP2-null mice exhibited increased angiogenesis and fibrotic encapsulation of the sponge. However, invasion of dense tissue was compromised, even though its overall density was increased. Furthermore, histomorphometry and biochemical assays demonstrated a significant increase in the extracellular distribution of matrix metalloproteinase (MMP) 2, but no change in the levels of active transforming growth factor-beta(1). The alterations in neovascularization, dense tissue invasion, and MMP2 in TSP2-null mice coincided with the deposition of TSP2 in the extracellular matrix of wild-type animals. These observations support the proposed role of TSP2 as a modulator of angiogenesis and matrix remodeling during tissue repair. In addition, they provide in vivo evidence for a newly proposed function of TSP2 as a modulator of extracellular MMP2 levels.

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon.

Science.gov (United States)

Duggal, K L

2016-01-01

A new technique is used to study a family of time-dependent null horizons, called " Evolving Null Horizons " (ENHs), of generalized Robertson-Walker (GRW) space-time [Formula: see text] such that the metric [Formula: see text] satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n )-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in [Formula: see text]. Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems.

Shearfree congruences of null geodesics and Killing tensors

International Nuclear Information System (INIS)

Dietz, W.; Ruediger, R.

1980-01-01

In this communication, the mutual connections between quantities that are generalizations of the notion of a a Killing vector field are investigated. A classification of these quantities in terms of a complex vector field αsub(a) is given. A common feature of all these quantities is that they imply the existence of a pair of shearfree geodetic null congruences. There are no explicit restrictions posed on the Ricci tensor. (author)

Two-loop string theory on null compactifications

International Nuclear Information System (INIS)

Cove, Henry C.D.; Szabo, Richard J.

2006-01-01

We compute the two-loop contributions to the free energy in the null compactification of perturbative string theory at finite temperature. The cases of bosonic, type II and heterotic strings are all treated. The calculation exploits an explicit reductive parametrization of the moduli space of infinite-momentum frame string worldsheets in terms of branched cover instantons. Various arithmetic and physical properties of the instanton sums are described. Applications to symmetric product orbifold conformal field theories and to the matrix string theory conjecture are also briefly discussed

Generalized frame of reference with null congruence

International Nuclear Information System (INIS)

Ferrarese, G.; Antonelli, R.

2000-01-01

The paper derives the main properties of a generalized frame of reference with a null congruence (light flux), by means of adapted non-holonomic techniques; then it studies the geometry of the space-time in terms of non-orthogonal projection: longitudinal and transverse covariant derivatives and corresponding commutation formulae, decomposition of the Riemann and gravitational tensors, lie derivatives of the Ricci rotation coefficients, transverse Bianchi identity. Application to the (absolute and relative) light flux: kinematical characteristics and screen, Sachs theorems etc. are also given

A new AQP1 null allele identified in a Gypsy woman who developed an anti-CO3 during her first pregnancy.

Science.gov (United States)

Saison, C; Peyrard, T; Landre, C; Ballif, B A; Schlosser, K A; Dettori, I; Chicheportiche, C; Nemeth, P; Cartron, J-P; Arnaud, L

2012-08-01

The Colton blood group antigens are carried by the AQP1 water channel. AQP1(-/-) individuals, also known as Colton-null since they express no Colton antigens, do not suffer any apparent clinical consequence but may develop a clinically significant alloantibody (anti-CO3) induced by transfusion or pregnancy. Identification and transfusion support of Colton-null patients are highly challenging, not only due to the extreme rarity of this phenotype, the lack of appropriate reagents in most laboratories, as well as the possibility of confusing it with the recently described CO:-1,-2,3,-4 phenotype where AQP1 is present. This study investigated a new Colton-null case and evaluated three commercially available anti-AQP1s to identify Colton-null red blood cell samples. The Colton-null phenotype was investigated by standard serological techniques, AQP1 sequencing, immunoblot and flow cytometry analyses. We identified and characterized the Colton-null phenotype in a Gypsy woman who developed an anti-CO3 during her first pregnancy. After developing a simple and robust method to sequence AQP1, we showed that she was apparently homozygous for a new AQP1 null allele, AQP1 601delG, whose product is not expressed in her red blood cells. We also established the Colton specificity of three commercially available anti-AQP1s in immunoblot and/or flow cytometry analyses. This Gypsy woman represents the sixth Colton-null case characterized at the serological, genetic and biochemical levels. The validation here of new reagents and methods should facilitate the identification of Colton-null individuals. © 2012 The Author(s). Vox Sanguinis © 2012 International Society of Blood Transfusion.

The Segmented Aperture Interferometric Nulling Testbed (SAINT) I: overview and air-side system description

Science.gov (United States)

Hicks, Brian A.; Lyon, Richard G.; Petrone, Peter; Ballard, Marlin; Bolcar, Matthew R.; Bolognese, Jeff; Clampin, Mark; Dogoda, Peter; Dworzanski, Daniel; Helmbrecht, Michael A.; Koca, Corina; Shiri, Ron

2016-07-01

This work presents an overview of the Segmented Aperture Interferometric Nulling Testbed (SAINT), a project that will pair an actively-controlled macro-scale segmented mirror with the Visible Nulling Coronagraph (VNC). SAINT will incorporate the VNC's demonstrated wavefront sensing and control system to refine and quantify end-to-end high-contrast starlight suppression performance. This pathfinder testbed will be used as a tool to study and refine approaches to mitigating instabilities and complex diffraction expected from future large segmented aperture telescopes.

Nav 1.8-null mice show stimulus-dependent deficits in spinal neuronal activity

Directory of Open Access Journals (Sweden)

Wood John N

2006-02-01

Full Text Available Abstract Background The voltage gated sodium channel Nav 1.8 has a highly restricted expression pattern to predominantly nociceptive peripheral sensory neurones. Behaviourally Nav 1.8-null mice show an increased acute pain threshold to noxious mechanical pressure and also deficits in inflammatory and visceral, but not neuropathic pain. Here we have made in vivo electrophysiology recordings of dorsal horn neurones in intact anaesthetised Nav 1.8-null mice, in response to a wide range of stimuli to further the understanding of the functional roles of Nav 1.8 in pain transmission from the periphery to the spinal cord. Results Nav 1.8-null mice showed marked deficits in the coding by dorsal horn neurones to mechanical, but not thermal, -evoked responses over the non-noxious and noxious range compared to littermate controls. Additionally, responses evoked to other stimulus modalities were also significantly reduced in Nav 1.8-null mice where the reduction observed to pinch > brush. The occurrence of ongoing spontaneous neuronal activity was significantly less in mice lacking Nav 1.8 compared to control. No difference was observed between groups in the evoked activity to electrical activity of the peripheral receptive field. Conclusion This study demonstrates that deletion of the sodium channel Nav 1.8 results in stimulus-dependent deficits in the dorsal horn neuronal coding to mechanical, but not thermal stimuli applied to the neuronal peripheral receptive field. This implies that Nav 1.8 is either responsible for, or associated with proteins involved in mechanosensation.

Review on study of multi-physics in environment engineering

International Nuclear Information System (INIS)

Liu Shanli; Zhao Jian; Sheng Jinchang

2006-01-01

This paper analyzes some problems on multi-field coupling ones between seepage mechanics and other physical and chemical processes (such as temperature field. stress field, solute transport. chemical action and so on) in environment engineering, it explains the research theory of multi-field coupling, it summarizes the abroad and domestic research about the model of multi-field problem and finally it looks into the future of research tendency in environment engineering. (authors)

Comparative metabolism of methacrylonitrile and acrylonitrile to cyanide using cytochrome P4502E1 and microsomal epoxide hydrolase-null mice

International Nuclear Information System (INIS)

El Hadri, L.; Chanas, B.; Ghanayem, B.I.

2005-01-01

Methacrylonitrile (MAN) and acrylonitrile (AN) are metabolized via glutathione (GSH) conjugation or epoxide formation. We have recently shown that CYP2E1 is essential for AN epoxidation and subsequent cyanide liberation. Current studies were designed to compare the enzymatic basis of MAN vs. AN metabolism to cyanide using wild-type (WT), CYP2E1-, and mEH-null mice. Mice received a single gavage dose of 0.047, 0.095, 0.19, or 0.38 mmol/kg of MAN or AN, and blood cyanide was measured at 1 or 3 h later. Blood cyanide levels in WT mice treated with AN or MAN were dose and time dependent. At equimolar doses, significantly higher levels of cyanide were detected in the blood of MAN- vs. AN-treated mice. Further, while significant reduction in blood cyanide levels occurred in MAN-treated CYP2E1-null vs. WT mice, AN metabolism to cyanide was largely abolished in CYP2E1-null mice. Pretreatment of mice with 1-aminobenzotriazole (ABT, CYP inhibitor) demonstrated that CYPs other than CYP2E1 also contribute to MAN metabolism to cyanide. Blood cyanide levels in mEH-null mice treated with aliphatic nitriles are generally lower than levels in similarly treated WT mice. Western blot analysis showed that expression of sEH was greater in male vs. female mice. The role of various epoxide hydrolases (EHs) in the production of cyanide from aliphatic nitriles is apparently structure and dose dependent. Regardless of genotype, significantly higher levels of cyanide were measured in the blood of male vs. female mice treated with MAN or AN. In conclusion, these data showed that (1) at equimolar doses, higher blood cyanide levels were detected in mice treated with MAN vs. AN; (2) while CYP2E1 is the only enzyme responsible for AN metabolism to cyanide, other CYPs also contribute to MAN metabolism; and (3) significantly higher levels of cyanide were measured in the blood of male vs. female treated with either nitrile. Higher blood cyanide levels in male vs. female mice and in MAN- vs. AN

The Fourier-Kelvin Stellar Interferometer (FKSI) Nulling Testbed II: Closed-loop Path Length Metrology And Control Subsystem

Science.gov (United States)

Frey, B. J.; Barry, R. K.; Danchi, W. C.; Hyde, T. T.; Lee, K. Y.; Martino, A. J.; Zuray, M. S.

2006-01-01

The Fourier-Kelvin Stellar Interferometer (FKSI) is a mission concept for an imaging and nulling interferometer in the near to mid-infrared spectral region (3-8 microns), and will be a scientific and technological pathfinder for upcoming missions including TPF-I/DARWIN, SPECS, and SPIRIT. At NASA's Goddard Space Flight Center, we have constructed a symmetric Mach-Zehnder nulling testbed to demonstrate techniques and algorithms that can be used to establish and maintain the 10(exp 4) null depth that will be required for such a mission. Among the challenges inherent in such a system is the ability to acquire and track the null fringe to the desired depth for timescales on the order of hours in a laboratory environment. In addition, it is desirable to achieve this stability without using conventional dithering techniques. We describe recent testbed metrology and control system developments necessary to achieve these goals and present our preliminary results.

Local differential geometry of null curves in conformally flat space-time

International Nuclear Information System (INIS)

Urbantke, H.

1989-01-01

The conformally invariant differential geometry of null curves in conformally flat space-times is given, using the six-vector formalism which has generalizations to higher dimensions. This is then paralleled by a twistor description, with a twofold merit: firstly, sometimes the description is easier in twistor terms, sometimes in six-vector terms, which leads to a mutual enlightenment of both; and secondly, the case of null curves in timelike pseudospheres or 2+1 Minkowski space we were only able to treat twistorially, making use of an invariant differential found by Fubini and Cech. The result is the expected one: apart from stated exceptional cases there is a conformally invariant parameter and two conformally invariant curvatures which, when specified in terms of this parameter, serve to characterize the curve up to conformal transformations. 12 refs. (Author)

Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling

Energy Technology Data Exchange (ETDEWEB)

Grell, Gilbert; Bokarev, Sergey I., E-mail: sergey.bokarev@uni-rostock.de; Kühn, Oliver [Institut für Physik, Universität Rostock, D-18051 Rostock (Germany); Winter, Bernd; Seidel, Robert [Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Aziz, Emad F. [Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Department of Physics, Freie Universität Berlin, Arnimalle 14, D-14159 Berlin (Germany); Aziz, Saadullah G. [Chemistry Department, Faculty of Science, King Abdulaziz University, 21589 Jeddah (Saudi Arabia)

2015-08-21

X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the restricted active space self-consistent field method including spin-orbit coupling is used to cope with this challenge and to calculate valence- and core-level photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the [Fe(H{sub 2}O){sub 6}]{sup 2+} complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approximation demonstrates distinct deviations from experiments.

Synchrony of sylvatic dengue isolations: a multi-host, multi-vector SIR model of dengue virus transmission in Senegal.

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Benjamin M Althouse

Full Text Available Isolations of sylvatic dengue-2 virus from mosquitoes, humans and non-human primates in Senegal show synchronized multi-annual dynamics over the past 50 years. Host demography has been shown to directly affect the period between epidemics in other pathogen systems, therefore, one might expect unsynchronized multi-annual cycles occurring in hosts with dramatically different birth rates and life spans. However, in Senegal, we observe a single synchronized eight-year cycle across all vector species, suggesting synchronized dynamics in all vertebrate hosts. In the current study, we aim to explore two specific hypotheses: 1 primates with different demographics will experience outbreaks of dengue at different periodicities when observed as isolated systems, and that coupling of these subsystems through mosquito biting will act to synchronize incidence; and 2 the eight-year periodicity of isolations observed across multiple primate species is the result of long-term cycling in population immunity in the host populations. To test these hypotheses, we develop a multi-host, multi-vector Susceptible, Infected, Removed (SIR model to explore the effects of coupling multiple host-vector systems of dengue virus transmission through cross-species biting rates. We find that under small amounts of coupling, incidence in the host species synchronize. Long-period multi-annual dynamics are observed only when prevalence in troughs reaches vanishingly small levels (< 10(-10, suggesting that these dynamics are inconsistent with sustained transmission in this setting, but are consistent with local dengue virus extinctions followed by reintroductions. Inclusion of a constant introduction of infectious individuals into the system causes the multi-annual periods to shrink, while the effects of coupling remain the same. Inclusion of a stochastic rate of introduction allows for multi-annual periods at a cost of reduced synchrony. Thus, we conclude that the eight-year period

Time asymmetric spacetimes near null and spatial infinity: I. Expansions of developments of conformally flat data

International Nuclear Information System (INIS)

Kroon, Juan Antonio Valiente

2004-01-01

The conformal Einstein equations and the representation of spatial infinity as a cylinder introduced by Friedrich are used to analyse the behaviour of the gravitational field near null and spatial infinity for the development of data which are asymptotically Euclidean, conformally flat and time asymmetric. Our analysis allows for initial data whose second fundamental form is more general than the one given by the standard Bowen-York ansatz. The conformal Einstein equations imply, upon evaluation on the cylinder at spatial infinity, a hierarchy of transport equations which can be used to calculate asymptotic expansions for the gravitational field in a recursive way. It is found that the solutions to these transport equations develop logarithmic divergences at the critical sets where null infinity meets spatial infinity. Associated with these, there is a series of quantities expressible in terms of the initial data (obstructions), which if zero, preclude the appearance of some of the logarithmic divergences. The obstructions are, in general, time asymmetric. That is, the obstructions at the intersection of future null infinity with spatial infinity are in general different from those obtained at the intersection of past null infinity with spatial infinity. The latter allows for the possibility of having spacetimes where future and past null infinity have different degrees of smoothness. Finally, it is shown that if both sets of obstructions vanish up to a certain order, then the initial data have to be asymptotically Schwarzschildean in a certain sense

Geometry of extended null supersymmetry in M theory

International Nuclear Information System (INIS)

Conamhna, Oisin A.P. Mac

2006-01-01

For supersymmetric spacetimes in 11 dimensions admitting a null Killing spinor, a set of explicit necessary and sufficient conditions for the existence of any number of arbitrary additional Killing spinors is derived. The necessary and sufficient conditions are comprised of algebraic relationships, linear in the spinorial components, between the spinorial components and their first derivatives, and the components of the spin connection and four-form. The integrability conditions for the Killing spinor equation are also analyzed in detail, to determine which components of the field equations are implied by arbitrary additional supersymmetries and the four-form Bianchi identity. This provides a complete formalism for the systematic and exhaustive investigation of all spacetimes with extended null supersymmetry in 11 dimensions. The formalism is employed to show that the general bosonic solution of 11 dimensional supergravity admitting a G 2 structure defined by four Killing spinors is either locally the direct product of R 1,3 with a seven-manifold of G 2 holonomy, or locally the Freund-Rubin direct product of AdS 4 with a seven-manifold of weak G 2 holonomy. In addition, all supersymmetric spacetimes admitting a (G 2 xR 7 )xR 2 structure are classified

Predicting self-pollution inside school buses using a CFD and multi-zone coupled model

Science.gov (United States)

Li, Fei; Lee, Eon S.; Liu, Junjie; Zhu, Yifang

2015-04-01

The in-cabin environment of a school bus is important for children's health. The pollutants from a bus's own exhaust contribute to children's overall exposure to air pollutants inside the school bus cabin. In this study, we adapted a coupled model originally developed for indoor environment to determine the relative contribution of the bus own exhaust to the in-cabin pollutant concentrations. The coupled model uses CFD (computational fluent dynamics) model to simulate outside concentration and CONTAM (a multi-zone model) for inside the school bus. The model was validated with experimental data in the literature. Using the validated model, we analyzed the effects of vehicle speed and tailpipe location on self-pollution inside the bus cabin. We confirmed that the pollution released from the tailpipe can penetrate into the bus cabin through gaps in the back emergency door. We found the pollution concentration inside school buses was the highest when buses were driven at a medium speed. In addition, locating the tailpipe on the side, behind the rear axle resulted in less self-pollution since there is less time for the suction effect to take place. The developed theoretical framework can be generalized to study other types of buses. These findings can be used in developing policy recommendations for reducing human exposure to air pollution inside buses.

Vacuum solutions admitting a geodesic null congruence with shear proportional to expansion

International Nuclear Information System (INIS)

Kupeli, A.H.

1988-01-01

Algebraically general, nontwisting solutions for the vacuum to vacuum generalized Kerr--Schild (GKS) transformation are obtained. These solutions admit a geodesic null congruence with shear proportional to expansion. In the Newman--Penrose formalism, if l/sup μ/ is chosen to be the null vector of the GKS transformation, this property is stated as σ = arho and Da = 0. It is assumed that a is a constant, and the background is chosen as a pp-wave solution. For generic values of a, the GKS metrics consist of the Kasner solutions. For a = +- (1 +- (2)/sup 1/2/), there are solutions with less symmetries including special cases of the Kota--Perjes and Lukacs solutions

Euclidean null controllability of linear systems with delays in state ...

African Journals Online (AJOL)

Sufficient conditions are developed for the Euclidean controllability of linear systems with delay in state and in control. Namely, if the uncontrolled system is uniformly asymptotically stable and the control equation proper, then the control system is Euclidean null controllable. Journal of the Nigerian Association of ...

A comment on the null geodesic equations in Schwarzschild geometry

International Nuclear Information System (INIS)

Rosa, M.A.F.; Rodrigues Junior, W.A.

1986-01-01

An integration of the null geodesic equations in the Schwarzschild geometry, which is valid to first order in GM/Rc 2 is presented. The solution is compared with others published in the literature and their range of validity is analysed. Some misunderstandings are also clarified. (Author) [pt

Wideband CMOS receivers exploiting simultaneous output balancing and noise/distortion canceling

NARCIS (Netherlands)

Blaakmeer, S.C.; Klumperink, Eric A.M.; Leenaerts, D.M.W.; Nauta, Bram

2008-01-01

Abstract— This paper deals with the problem of realizing wideband receiver front-ends in downscaled CMOSTechnologies, which are highly wanted for multi-standard radio receivers and cognitive radio applications. Instead of using many narrowband inductor based receivers, we prefer the use of one

Argonaute-2-null embryonic stem cells are retarded in self-renewal ...

Indian Academy of Sciences (India)

Present address: Institute of Stem Cells and Regenerative Medicine, Bangalore, India ... [Chandra Shekar P, Naim A, Partha Sarathi D and Kumar S 2011 Argonaute-2-null embryonic stem cells are retarded in self-renewal ..... Research, India.

The null-event method in computer simulation

International Nuclear Information System (INIS)

Lin, S.L.

1978-01-01

The simulation of collisions of ions moving under the influence of an external field through a neutral gas to non-zero temperatures is discussed as an example of computer models of processes in which a probe particle undergoes a series of interactions with an ensemble of other particles, such that the frequency and outcome of the events depends on internal properties of the second particles. The introduction of null events removes the need for much complicated algebra, leads to a more efficient simulation and reduces the likelihood of logical error. (Auth.)

Isolation of two independent allyl alcohol resistant Adh-1 null mutants following selection of pollen and seeds.

NARCIS (Netherlands)

Wisman, E.; Ramanna, M.S.; Zabel, P.

1993-01-01

The Adh-1 null mutant (B15-1-8) isolated previously was used to establish conditions that allow the selection of ADH-deficient pollen grains and seeds of tomato. New Adh-1 null mutants were then selected among the progenies derived from crosses between the genetically unstable tomato lines Yvms,

Exactly solvable spin–glass models with ferromagnetic couplings: The spherical multi-p-spin model in a self-induced field

International Nuclear Information System (INIS)

Crisanti, Andrea; Leuzzi, Luca

2013-01-01

We report some results on the quenched disordered Spherical multi-p-Spin Model in presence of ferromagnetic couplings. In particular, we present the phase diagrams of some representative cases that schematically describe, in the mean-field approximation, the behavior of most known transitions in glassy materials, including dynamic arrest in super-cooled liquids, amorphous–amorphous transitions and spin–glass transitions. A simplified notation is introduced in order to compute systems properties in terms of an effective, self-induced, field encoding the whole ferromagnetic information

Cell therapy of congenital corneal diseases with umbilical mesenchymal stem cells: lumican null mice.

Directory of Open Access Journals (Sweden)

Hongshan Liu

Full Text Available BACKGROUND: Keratoplasty is the most effective treatment for corneal blindness, but suboptimal medical conditions and lack of qualified medical personnel and donated cornea often prevent the performance of corneal transplantation in developing countries. Our study aims to develop alternative treatment regimens for congenital corneal diseases of genetic mutation. METHODOLOGY/PRINCIPAL FINDINGS: Human mesenchymal stem cells isolated from neonatal umbilical cords were transplanted to treat thin and cloudy corneas of lumican null mice. Transplantation of umbilical mesenchymal stem cells significantly improved corneal transparency and increased stromal thickness of lumican null mice, but human umbilical hematopoietic stem cells failed to do the same. Further studies revealed that collagen lamellae were re-organized in corneal stroma of lumican null mice after mesenchymal stem cell transplantation. Transplanted umbilical mesenchymal stem cells survived in the mouse corneal stroma for more than 3 months with little or no graft rejection. In addition, these cells assumed a keratocyte phenotype, e.g., dendritic morphology, quiescence, expression of keratocyte unique keratan sulfated keratocan and lumican, and CD34. Moreover, umbilical mesenchymal stem cell transplantation improved host keratocyte functions, which was verified by enhanced expression of keratocan and aldehyde dehydrogenase class 3A1 in lumican null mice. CONCLUSIONS/SIGNIFICANCE: Umbilical mesenchymal stem cell transplantation is a promising treatment for congenital corneal diseases involving keratocyte dysfunction. Unlike donated corneas, umbilical mesenchymal stem cells are easily isolated, expanded, stored, and can be quickly recovered from liquid nitrogen when a patient is in urgent need.

User's manual for DELSOL2: a computer code for calculating the optical performance and optimal system design for solar-thermal central-receiver plants

Energy Technology Data Exchange (ETDEWEB)

Dellin, T.A.; Fish, M.J.; Yang, C.L.

1981-08-01

DELSOL2 is a revised and substantially extended version of the DELSOL computer program for calculating collector field performance and layout, and optimal system design for solar thermal central receiver plants. The code consists of a detailed model of the optical performance, a simpler model of the non-optical performance, an algorithm for field layout, and a searching algorithm to find the best system design. The latter two features are coupled to a cost model of central receiver components and an economic model for calculating energy costs. The code can handle flat, focused and/or canted heliostats, and external cylindrical, multi-aperture cavity, and flat plate receivers. The program optimizes the tower height, receiver size, field layout, heliostat spacings, and tower position at user specified power levels subject to flux limits on the receiver and land constraints for field layout. The advantages of speed and accuracy characteristic of Version I are maintained in DELSOL2.

GPU Acceleration of DSP for Communication Receivers.

Science.gov (United States)

Gunther, Jake; Gunther, Hyrum; Moon, Todd

2017-09-01

Graphics processing unit (GPU) implementations of signal processing algorithms can outperform CPU-based implementations. This paper describes the GPU implementation of several algorithms encountered in a wide range of high-data rate communication receivers including filters, multirate filters, numerically controlled oscillators, and multi-stage digital down converters. These structures are tested by processing the 20 MHz wide FM radio band (88-108 MHz). Two receiver structures are explored: a single channel receiver and a filter bank channelizer. Both run in real time on NVIDIA GeForce GTX 1080 graphics card.

Likelihood of Null Effects of Large NHLBI Clinical Trials Has Increased over Time.

Directory of Open Access Journals (Sweden)

Robert M Kaplan

Full Text Available We explore whether the number of null results in large National Heart Lung, and Blood Institute (NHLBI funded trials has increased over time.We identified all large NHLBI supported RCTs between 1970 and 2012 evaluating drugs or dietary supplements for the treatment or prevention of cardiovascular disease. Trials were included if direct costs >$500,000/year, participants were adult humans, and the primary outcome was cardiovascular risk, disease or death. The 55 trials meeting these criteria were coded for whether they were published prior to or after the year 2000, whether they registered in clinicaltrials.gov prior to publication, used active or placebo comparator, and whether or not the trial had industry co-sponsorship. We tabulated whether the study reported a positive, negative, or null result on the primary outcome variable and for total mortality.17 of 30 studies (57% published prior to 2000 showed a significant benefit of intervention on the primary outcome in comparison to only 2 among the 25 (8% trials published after 2000 (χ2=12.2,df= 1, p=0.0005. There has been no change in the proportion of trials that compared treatment to placebo versus active comparator. Industry co-sponsorship was unrelated to the probability of reporting a significant benefit. Pre-registration in clinical trials.gov was strongly associated with the trend toward null findings.The number NHLBI trials reporting positive results declined after the year 2000. Prospective declaration of outcomes in RCTs, and the adoption of transparent reporting standards, as required by clinicaltrials.gov, may have contributed to the trend toward null findings.

Population estimators or progeny tests: what is the best method to assess null allele frequencies at SSR loci?

NARCIS (Netherlands)

Oddou-Muratorio, S.; Vendramin, G.G.; Buiteveld, J.; Fady, B.

2009-01-01

Nuclear SSRs are notorious for having relatively high frequencies of null alleles, i.e. alleles that fail to amplify and are thus recessive and undetected in heterozygotes. In this paper, we compare two kinds of approaches for estimating null allele frequencies at seven nuclear microsatellite

MAPK signaling pathways and HDAC3 activity are disrupted during differentiation of emerin-null myogenic progenitor cells

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Carol M. Collins

2017-04-01

Full Text Available Mutations in the gene encoding emerin cause Emery–Dreifuss muscular dystrophy (EDMD. Emerin is an integral inner nuclear membrane protein and a component of the nuclear lamina. EDMD is characterized by skeletal muscle wasting, cardiac conduction defects and tendon contractures. The failure to regenerate skeletal muscle is predicted to contribute to the skeletal muscle pathology of EDMD. We hypothesize that muscle regeneration defects are caused by impaired muscle stem cell differentiation. Myogenic progenitors derived from emerin-null mice were used to confirm their impaired differentiation and analyze selected myogenic molecular pathways. Emerin-null progenitors were delayed in their cell cycle exit, had decreased myosin heavy chain (MyHC expression and formed fewer myotubes. Emerin binds to and activates histone deacetylase 3 (HDAC3. Here, we show that theophylline, an HDAC3-specific activator, improved myotube formation in emerin-null cells. Addition of the HDAC3-specific inhibitor RGFP966 blocked myotube formation and MyHC expression in wild-type and emerin-null myogenic progenitors, but did not affect cell cycle exit. Downregulation of emerin was previously shown to affect the p38 MAPK and ERK/MAPK pathways in C2C12 myoblast differentiation. Using a pure population of myogenic progenitors completely lacking emerin expression, we show that these pathways are also disrupted. ERK inhibition improved MyHC expression in emerin-null cells, but failed to rescue myotube formation or cell cycle exit. Inhibition of p38 MAPK prevented differentiation in both wild-type and emerin-null progenitors. These results show that each of these molecular pathways specifically regulates a particular stage of myogenic differentiation in an emerin-dependent manner. Thus, pharmacological targeting of multiple pathways acting at specific differentiation stages may be a better therapeutic approach in the future to rescue muscle regeneration in vivo.

GST M1-T1 null allele frequency patterns in geographically assorted human populations: a phylogenetic approach.

Directory of Open Access Journals (Sweden)

Senthilkumar Pitchalu Kasthurinaidu

Full Text Available Genetic diversity in drug metabolism and disposition is mainly considered as the outcome of the inter-individual genetic variation in polymorphism of drug-xenobiotic metabolizing enzyme (XME. Among the XMEs, glutathione-S-transferases (GST gene loci are an important candidate for the investigation of diversity in allele frequency, as the deletion mutations in GST M1 and T1 genotypes are associated with various cancers and genetic disorders of all major Population Affiliations (PAs. Therefore, the present population based phylogenetic study was focused to uncover the frequency distribution pattern in GST M1 and T1 null genotypes among 45 Geographically Assorted Human Populations (GAHPs. The frequency distribution pattern for GST M1 and T1 null alleles have been detected in this study using the data derived from literatures representing 44 populations affiliated to Africa, Asia, Europe, South America and the genome of PA from Gujarat, a region in western India. Allele frequency counting for Gujarat PA and scattered plot analysis for geographical distribution among the PAs were performed in SPSS-21. The GST M1 and GST T1 null allele frequencies patterns of the PAs were computed in Seqboot, Gendist program of Phylip software package (3.69 versions and Unweighted Pair Group method with Arithmetic Mean in Mega-6 software. Allele frequencies from South African Xhosa tribe, East African Zimbabwe, East African Ethiopia, North African Egypt, Caucasian, South Asian Afghanistan and South Indian Andhra Pradesh have been identified as the probable seven patterns among the 45 GAHPs investigated in this study for GST M1-T1 null genotypes. The patternized null allele frequencies demonstrated in this study for the first time addresses the missing link in GST M1-T1 null allele frequencies among GAHPs.

The null hypothesis of GSEA, and a novel statistical model for competitive gene set analysis

DEFF Research Database (Denmark)

Debrabant, Birgit

2017-01-01

MOTIVATION: Competitive gene set analysis intends to assess whether a specific set of genes is more associated with a trait than the remaining genes. However, the statistical models assumed to date to underly these methods do not enable a clear cut formulation of the competitive null hypothesis....... This is a major handicap to the interpretation of results obtained from a gene set analysis. RESULTS: This work presents a hierarchical statistical model based on the notion of dependence measures, which overcomes this problem. The two levels of the model naturally reflect the modular structure of many gene set...... analysis methods. We apply the model to show that the popular GSEA method, which recently has been claimed to test the self-contained null hypothesis, actually tests the competitive null if the weight parameter is zero. However, for this result to hold strictly, the choice of the dependence measures...

A few insights into the nature of classical and quantum gravity via null-strut calculus

International Nuclear Information System (INIS)

Kheyfets, Arkady

1989-01-01

Null-strut calculus is a 3 + 1 formulation of standard Regge calculus, wherein the dynamics of 3-geometry is propagated in time along light rays, or 'null struts'. However, just as Regge calculus is a discrete and geometric tool for the description of Einstein's theory of gravitation, so too NSC offers itself as a discrete and geometric tool for the description of Einstein's spacetime as the dynamics of discrete spacelike 3-geometries in time, or discrete geometrodynamics. It has for its objectives to provide a discrete model of a 3 + 1 split of spacetime into space plus time, while in so doing to preserve and illuminate the geometric content of Einstein's theory of gravity. The feature of 'light-cone-produced duality' is central to null-strut calculus. This paper will capitalise on this feature, and will attempt to provide some insights into the nature of classical and quantum gravity. (Author)

Null geodesics and wave front singularities in the Gödel space-time

Science.gov (United States)

Kling, Thomas P.; Roebuck, Kevin; Grotzke, Eric

2018-01-01

We explore wave fronts of null geodesics in the Gödel metric emitted from point sources both at, and away from, the origin. For constant time wave fronts emitted by sources away from the origin, we find cusp ridges as well as blue sky metamorphoses where spatially disconnected portions of the wave front appear, connect to the main wave front, and then later break free and vanish. These blue sky metamorphoses in the constant time wave fronts highlight the non-causal features of the Gödel metric. We introduce a concept of physical distance along the null geodesics, and show that for wave fronts of constant physical distance, the reorganization of the points making up the wave front leads to the removal of cusp ridges.

Kinetic modeling of particle acceleration in a solar null point reconnection region

DEFF Research Database (Denmark)

Baumann, Gisela; Haugbølle, Troels; Nordlund, Åke

2013-01-01

The primary focus of this paper is on the particle acceleration mechanism in solar coronal 3D reconnection null-point regions. Starting from a potential field extrapolation of a SOHO magnetogram taken on 2002 November 16, we first performed MHD simulations with horizontal motions observed by SOHO...... particles and 3.5 billion grid cells of size 17.5\\,km --- these simulations offer a new opportunity to study particle acceleration in solar-like settings....... applied to the photospheric boundary of the computational box. After a build-up of electric current in the fan-plane of the null-point, a sub-section of the evolved MHD data was used as initial and boundary conditions for a kinetic particle-in-cell model of the plasma. We find that sub...

No actual measurement … was required: Maxwell and Cavendish's null method for the inverse square law of electrostatics.

Science.gov (United States)

Falconer, Isobel

In 1877 James Clerk Maxwell and his student Donald MacAlister refined Henry Cavendish's 1773 null experiment demonstrating the absence of electricity inside a charged conductor. This null result was a mathematical prediction of the inverse square law of electrostatics, and both Cavendish and Maxwell took the experiment as verifying the law. However, Maxwell had already expressed absolute conviction in the law, based on results of Michael Faraday's. So, what was the value to him of repeating Cavendish's experiment? After assessing whether the law was as secure as he claimed, this paper explores its central importance to the electrical programme that Maxwell was pursuing. It traces the historical and conceptual re-orderings through which Maxwell established the law by constructing a tradition of null tests and asserting the superior accuracy of the method. Maxwell drew on his developing 'doctrine of method' to identify Cavendish's experiment as a member of a wider class of null methods. By doing so, he appealed to the null practices of telegraph engineers, diverted attention from the flawed logic of the method, and sought to localise issues around the mapping of numbers onto instrumental indications, on the grounds that 'no actual measurement … was required'. Copyright © 2017 Elsevier Ltd. All rights reserved.

Glutathione S-transferase M1 null genotype: lack of association with tumour characteristics and survival in advanced breast cancer

International Nuclear Information System (INIS)

Lizard-Nacol, Sarab; Coudert, Bruno; Colosetti, Pascal; Riedinger, Jean-Marc; Fargeot, Pierre; Brunet-Lecomte, Patrick

1999-01-01

Glutathione S-transferase (GST)M1, a member of the μ class GST gene family, has been shown to be polymorphic because of a partial gene deletion. This results in a failure to express the GSTM1 gene in 50-60% of individuals. Several studies have demonstrated a possible link with the GSTM1-null genotype and susceptibility to cancer. Furthermore, a GSTM1 isoenzyme has been positively associated with protective effect against mutagenic drugs, such as alkylating agents and anthracyclines. To determine whether GSTM1 polymorphisms are associated with tumour characteristics and survival in advanced breast cancer patients, and whether it may constitute a prognostic factor. We genotyped 92 patients receiving primary chemotherapy, which included cyclophosphamide, doxorubicine and 5-fluorouracil. The relationships between allelism at GSTM1 and clinicopathological parameters including age, menopausal status, tumour size, grade hormone receptors, involved nodes and p53 gene mutations were analysed. Of the patients with GSTM1-positive genotype, tissue samples obtained before and after treatment were available from 28 cases, allowing RNA extraction and GSTM1 expression by reverse transcription polymerase chain reaction. Relationships with clinical response to chemotherapy, and disease-free and overall survival were also evaluated. The data obtained was analysed using logistic regression to estimate the odds ratio and 95% confidence interval. Of 92 patients, 57.6% (n = 53) were classified as heritably GSTM1-deficient, and 42.4% (n = 39) were of the GSTM1-positive genotype. There were no statistically significant relationships between GSTM1-null genotype and the clinicopathological parameters analysed. No relationship was observed between GSTM1 RNA expression and objective clinical response to chemotherapy. Objective clinical response to chemotherapy was related only to clinical tumour size (P = 0.0177) and to the absence of intraductal carcinoma (P = 0.0013). GSTM1-null genotype

Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results

Science.gov (United States)

Lyon, Richard G.

2008-01-01

The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched to heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime ( 5 year goal) and will revisit planets at least three times at intervals of 9 months. The starlight suppression approach consists of a visible nulling coronagraph (VNC) that enables high order starlight suppression in broadband light. To demonstrate the VNC approach and advance it's technology readiness the NASA Goddard Space Flight Center and Lockheed-Martin have developed a laboratory VNC and have demonstrated white light nulling. We will discuss our ongoing VNC work and show the latest results from the VNC testbed,

Design And Construction Of Wireless Charging System Using Inductive Coupling

Directory of Open Access Journals (Sweden)

Do Lam Mung

2015-06-01

Full Text Available Abstract Wireless charging system described by using the method of inductive coupling. In this project oscillation circuit converts DC energy to AC energytransmitter coil to transmit magnetic field by passing frequency and then induce the receiver coil. The properties of Induction coupling are wavemagnetic field-wideband rangevery shortcm efficiencyhight and operation frequencyLF-bandseveral handred kHz.The project shows as a small charging for 5V battery of phone in this method. The system bases on coupling magnetic field then designed and constructed as two parts. There are transmitter part and receiver part. The transmitter coil transmitter part transmits coupling magnetic field to receiver coil receiver part by passing frequency at about 1.67MHz. The Amperes law Biot-Savart law and Faraday law are used to calculate the inductive coupling between the transmitter coil and the receiver coil. The calculation of this law shows how many power transfer in receiver part when how many distance between the transmitter coil and the receiver coil. The system is safe for users and neighbouring electronic devices. To get more accurate wireless charging system it needs to change the design of the following keywords.

Intimate Partner Violence in Interracial Couples: A Comparison to White and Ethnic Minority Monoracial Couples

Science.gov (United States)

Fusco, Rachel A.

2010-01-01

The number of interracial couples in the U.S. is growing, but they often receive little support. Although previous studies have explored the relationship between low social support and decreased relationship satisfaction in interracial couples, there are few studies on intimate partner violence (IPV) in these couples. To better understand IPV in…

Expression of extracellular matrix components is disrupted in the immature and adult estrogen receptor β-null mouse ovary.

Directory of Open Access Journals (Sweden)

Alexandra Zalewski

Full Text Available Within the ovary, Estrogen Receptor β (ERβ is localized to the granulosa cells of growing follicles. 17β-estradiol (E2 acting via ERβ augments the actions of follicle stimulating hormone in granulosa cells, leading to granulosa cell differentiation and formation of a preovulatory follicle. Adult ERβ-null females are subfertile and possess ovaries with reduced numbers of growing follicles and corpora lutea. Because the majority of E2 production by granulosa cells occurs once puberty is reached, a role for ERβ in the ovary prior to puberty has not been well examined. We now provide evidence that lack of ERβ disrupts gene expression as early as post-natal day (PND 13, and in particular, we identify a number of genes of the extracellular matrix (ECM that are significantly higher in ERβ-null follicles than in wildtype (WT follicles. Considerable changes occur to the ECM occur during normal folliculogenesis to allow for the dramatic growth, cellular differentiation, and reorganization of the follicle from the primary to preovulatory stage. Using quantitative PCR and immunofluorescence, we now show that several ECM genes are aberrantly overexpressed in ERβ-null follicles. We find that Collagen11a1, a protein highly expressed in cartilage, is significantly higher in ERβ-null follicles than WT follicles as early as PND 13, and this heightened expression continues through PND 23-29 into adulthood. Similarly, Nidogen 2, a highly conserved basement membrane glycoprotein, is elevated in ERβ-null follicles at PND 13 into adulthood, and is elevated specifically in the ERβ-null focimatrix, a basal lamina-like matrix located between granulosa cells. Focimatrix laminin and Collagen IV expression were also higher in ERβ-null ovaries than in WT ovaries at various ages. Our findings suggest two novel observations: a that ERβ regulates granulosa cell gene expression ovary prior to puberty, and b that ERβ regulates expression of ECM components in the

Numerical simulations of coupled problems in engineering

CERN Document Server

2014-01-01

This book presents and discusses mathematical models, numerical methods and computational techniques used for solving coupled problems in science and engineering. It takes a step forward in the formulation and solution of real-life problems with a multidisciplinary vision, accounting for all of the complex couplings involved in the physical description. Simulation of multifaceted physics problems is a common task in applied research and industry. Often a suitable solver is built by connecting together several single-aspect solvers into a network. In this book, research in various fields was selected for consideration: adaptive methodology for multi-physics solvers, multi-physics phenomena and coupled-field solutions, leading to computationally intensive structural analysis. The strategies which are used to keep these problems computationally affordable are of special interest, and make this an essential book.

Hamilton-Jacobi formalism for Podolsky's electromagnetic theory on the null-plane

Science.gov (United States)

Bertin, M. C.; Pimentel, B. M.; Valcárcel, C. E.; Zambrano, G. E. R.

2017-08-01

We develop the Hamilton-Jacobi formalism for Podolsky's electromagnetic theory on the null-plane. The main goal is to build the complete set of Hamiltonian generators of the system as well as to study the canonical and gauge transformations of the theory.

Working memory training in healthy young adults: Support for the null from a randomized comparison to active and passive control groups.

Science.gov (United States)

Clark, Cameron M; Lawlor-Savage, Linette; Goghari, Vina M

2017-01-01

Training of working memory as a method of increasing working memory capacity and fluid intelligence has received much attention in recent years. This burgeoning field remains highly controversial with empirically-backed disagreements at all levels of evidence, including individual studies, systematic reviews, and even meta-analyses. The current study investigated the effect of a randomized six week online working memory intervention on untrained cognitive abilities in a community-recruited sample of healthy young adults, in relation to both a processing speed training active control condition, as well as a no-contact control condition. Results of traditional null hypothesis significance testing, as well as Bayesian factor analyses, revealed support for the null hypothesis across all cognitive tests administered before and after training. Importantly, all three groups were similar at pre-training for a variety of individual variables purported to moderate transfer of training to fluid intelligence, including personality traits, motivation to train, and expectations of cognitive improvement from training. Because these results are consistent with experimental trials of equal or greater methodological rigor, we suggest that future research re-focus on: 1) other promising interventions known to increase memory performance in healthy young adults, and; 2) examining sub-populations or alternative populations in which working memory training may be efficacious.

Microelectrode voltammetry of multi-electron transfers complicated by coupled chemical equilibria: a general theory for the extended square scheme.

Science.gov (United States)

Laborda, Eduardo; Gómez-Gil, José María; Molina, Angela

2017-06-28

A very general and simple theoretical solution is presented for the current-potential-time response of reversible multi-electron transfer processes complicated by homogeneous chemical equilibria (the so-called extended square scheme). The expressions presented here are applicable regardless of the number of electrons transferred and coupled chemical processes, and they are particularized for a wide variety of microelectrode geometries. The voltammetric response of very different systems presenting multi-electron transfers is considered for the most widely-used techniques (namely, cyclic voltammetry, square wave voltammetry, differential pulse voltammetry and steady state voltammetry), studying the influence of the microelectrode geometry and the number and thermodynamics of the (electro)chemical steps. Most appropriate techniques and procedures for the determination of the 'interaction' between successive transfers are discussed. Special attention is paid to those situations where homogeneous chemical processes, such as protonation, complexation or ion association, affect the electrochemical behaviour of the system by different stabilization of the oxidation states.

Spinal cord compression injury in lysophosphatidic acid 1 receptor-null mice promotes maladaptive pronociceptive descending control.

Science.gov (United States)

Suardíaz, M; Galan-Arriero, I; Avila-Martin, G; Estivill-Torrús, G; de Fonseca, F R; Chun, J; Gómez-Soriano, J; Bravo-Esteban, E; Taylor, J

2016-02-01

Although activation of the lysophosphatidic acid receptor 1 (LPA1) is known to mediate pronociceptive effects in peripheral pain models, the role of this receptor in the modulation of spinal nociception following spinal cord injury (SCI) is unknown. In this study, LPA1 regulation of spinal excitability mediated by supraspinal descending antinociceptive control systems was assessed following SCI in both wild-type (WT) and maLPA1-null receptor mice. The effect of a T8 spinal compression in WT and maLPA1-null mice was assessed up to 1 month after SCI using histological, immunohistochemical and behavioural techniques analysis including electrophysiological recording of noxious toes-Tibialis Anterior (TA) stimulus-response reflex activity. The effect of a T3 paraspinal transcutaneous electrical conditioning stimulus on TA noxious reflex temporal summation was also assessed. Histological analysis demonstrated greater dorsolateral funiculus damage after SCI in maLPA1-null mice, without a change in the stimulus-response function of the TA noxious reflex when compared to WT mice. While T3 conditioning stimulation in the WT group inhibited noxious TA reflex temporal summation after SCI, this stimulus strongly excited TA reflex temporal summation in maLPA1-null mice. The functional switch from descending inhibition to maladaptive facilitation of central excitability of spinal nociception demonstrated in maLPA1-null mice after SCI was unrelated to a general change in reflex activity. These data suggest that the LPA1 receptor is necessary for inhibition of temporal summation of noxious reflex activity, partly mediated via long-tract descending modulatory systems acting at the spinal level. © 2015 European Pain Federation - EFIC®

Pituitary null cell adenoma in a domestic llama (Lama glama).

Science.gov (United States)

Chalkley, M D; Kiupel, M; Draper, A C E

2014-07-01

Pituitary gland neoplasia has been reported rarely in camelids. A 12-year-old neutered male llama (Lama glama) presented with lethargy, inappetence and neurological signs. On physical examination, the llama was mentally dull and exhibited compulsive pacing and circling to the left. Complete blood count and serum biochemistry revealed haemoconcentration, mild hypophosphataemia, hyperglycaemia, hypercreatininaemia and hyperalbuminaemia. Humane destruction was elected due to rapid clinical deterioration and poor prognosis. Post-mortem examination revealed a pituitary macroadenoma and bilateral internal hydrocephalus. Microscopically, the pituitary tumour was composed of neoplastic chromophobic pituitary cells. Ultrastructural studies revealed similar neoplastic cells to those previously described in human null cell adenomas. Immunohistochemically, the neoplastic cells were strongly immunoreactive for neuroendocrine markers (synaptophysin and chromogranin A), but did not exhibit immunoreactivity for epithelial, mesenchymal, neuronal and all major pituitary hormone markers (adrenocorticotropic hormone, follicle stimulating hormone, growth hormone, luteinizing hormone, melanocyte-stimulating hormone, prolactin and thyroid stimulating hormone), consistent with the diagnosis of a pituitary null cell adenoma. This is the first report of pituitary neoplasia in a llama. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identifying the null subject: evidence from event-related brain potentials.

Science.gov (United States)

Demestre, J; Meltzer, S; García-Albea, J E; Vigil, A

1999-05-01

Event-related brain potentials (ERPs) were recorded during spoken language comprehension to study the on-line effects of gender agreement violations in controlled infinitival complements. Spanish sentences were constructed in which the complement clause contained a predicate adjective marked for syntactic gender. By manipulating the gender of the antecedent (i.e., the controller) of the implicit subject while holding constant the gender of the adjective, pairs of grammatical and ungrammatical sentences were created. The detection of such a gender agreement violation would indicate that the parser had established the coreference relation between the null subject and its antecedent. The results showed a complex biphasic ERP (i.e., an early negativity with prominence at anterior and central sites, followed by a centroparietal positivity) in the violating condition as compared to the non-violating conditions. The brain reacts to NP-adjective gender agreement violations within a few hundred milliseconds of their occurrence. The data imply that the parser has properly coindexed the null subject of an infinitive clause with its antecedent.

Influence of grain boundary connectivity on the trapped magnetic flux of multi-seeded bulk superconductors

Energy Technology Data Exchange (ETDEWEB)

Deng, Z., E-mail: zgdeng@gmail.com [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan); Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Hara, S.; Uetake, T.; Izumi, M. [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan)

2011-09-15

Four different performance multi-seeded YBCO bulks as representatives. A coupling ratio to reflect the coupling quality of GBs inside multi-seeded bulks. An averaged trapped magnetic flux density parameter was introduced. The top-seeded melt-growth process with multi-seeding technique provides a promising way to fabricate large-sized bulk superconductors in an economical way. To understand the essential characteristics of the multi-seeded bulks, the paper reports the influence of the grain boundary (GB) coupling or connectivity on the total trapped magnetic flux. The coupling ratio, the lowest trapped flux density in the GB area to the averaged top value of the two neighboring peak trapped fields, is introduced to reflect the coupling quality of GBs inside a multi-seeded bulk. By the trapped flux density measurement of four different performance multi-seeded YBCO bulk samples as representatives, it was found that the GB coupling plays an important role for the improvement of the total trapped magnetic flux; moreover, somewhat more significant than the widely used parameter of the peak trapped fields to evaluate the physical performance of bulk samples. This characteristic is different with the case of the well-grown single-grain bulks.

Water jacket for solid particle solar receiver

Science.gov (United States)

Wasyluk, David T.

2018-03-20

A solar receiver includes: water jacket panels each having a light-receiving side and a back side with a watertight sealed plenum defined in-between; light apertures passing through the watertight sealed plenums to receive light from the light-receiving sides of the water jacket panels; a heat transfer medium gap defined between the back sides of the water jacket panels and a cylindrical back plate; and light channeling tubes optically coupled with the light apertures and extending into the heat transfer medium gap. In some embodiments ends of the light apertures at the light receiving side of the water jacket panel are welded together to define at least a portion of the light-receiving side. A cylindrical solar receiver may be constructed using a plurality of such water jacket panels arranged with their light-receiving sides facing outward.

Elements of a compatible optimization theory for coupled systems; Elements d'une theorie de l'optimisation compatible de systemes couples

Energy Technology Data Exchange (ETDEWEB)

Bonnemay, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-07-01

The first theory deals with the compatible optimization in coupled systems. A game theory for two players and with a non-zero sum is first developed. The conclusions are then extended to the case of a game with any finite number of players. After this essentially static study, the dynamic aspect of the problem is applied to the case of games which evolve. By applying PONTRYAGIN maximum principle it is possible to derive a compatible optimisation theorem which constitutes a necessary condition. (author) [French] La premiere these traite de l'optimalisation compatible des systemes couples. Une theorie du jeu a deux joueurs et a somme non nulle est d'abord developpee. Ses conclusions sont etendues ensuite au jeu a un nombre fini quelconque de joueurs. Apres cette etude essentiellement statique, l'aspect dynamique du probleme est introduit dans les jeux evolutifs. L'application du principe du maximum de PONTRYAGIN permet d'enoncer un theoreme d'optimalite compatible qui constitue une condition necessaire. (auteur)

Multi-constituent determination and fingerprint analysis of Scutellaria indica L. using ultra high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Science.gov (United States)

Liang, Xianrui; Zhao, Cui; Su, Weike

2015-11-01

An ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method integrating multi-constituent determination and fingerprint analysis has been established for quality assessment and control of Scutellaria indica L. The optimized method possesses the advantages of speediness, efficiency, and allows multi-constituents determination and fingerprint analysis in one chromatographic run within 11 min. 36 compounds were detected, and 23 of them were unequivocally identified or tentatively assigned. The established fingerprint method was applied to the analysis of ten S. indica samples from different geographic locations. The quality assessment was achieved by using principal component analysis. The proposed method is useful and reliable for the characterization of multi-constituents in a complex chemical system and the overall quality assessment of S. indica. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamics of multi-frequency oscillator ensembles with resonant coupling

International Nuclear Information System (INIS)

Lueck, S.; Pikovsky, A.

2011-01-01

We study dynamics of populations of resonantly coupled oscillators having different frequencies. Starting from the coupled van der Pol equations we derive the Kuramoto-type phase model for the situation, where the natural frequencies of two interacting subpopulations are in relation 2:1. Depending on the parameter of coupling, ensembles can demonstrate fully synchronous clusters, partial synchrony (only one subpopulation synchronizes), or asynchrony in both subpopulations. Theoretical description of the dynamics based on the Watanabe-Strogatz approach is developed. -- Highlights: → Kuramoto model is generalized on the case of resonantly interacting oscillators having frequency ratio 2:1. → Regimes of full and partial synchrony, as well as non-synchronous ones are reported. → Analytical description is developed on the basis of the Watanabe-Strogatz approach.

Dynamics of multi-frequency oscillator ensembles with resonant coupling

Energy Technology Data Exchange (ETDEWEB)

Lueck, S. [Department of Physics and Astronomy, Potsdam University, Karl-Liebknecht-Str. 24-25, 14476 Potsdam (Germany); Pikovsky, A., E-mail: pikovsky@stat.physik.uni-potsdam.de [Department of Physics and Astronomy, Potsdam University, Karl-Liebknecht-Str. 24-25, 14476 Potsdam (Germany)

2011-07-11

We study dynamics of populations of resonantly coupled oscillators having different frequencies. Starting from the coupled van der Pol equations we derive the Kuramoto-type phase model for the situation, where the natural frequencies of two interacting subpopulations are in relation 2:1. Depending on the parameter of coupling, ensembles can demonstrate fully synchronous clusters, partial synchrony (only one subpopulation synchronizes), or asynchrony in both subpopulations. Theoretical description of the dynamics based on the Watanabe-Strogatz approach is developed. -- Highlights: → Kuramoto model is generalized on the case of resonantly interacting oscillators having frequency ratio 2:1. → Regimes of full and partial synchrony, as well as non-synchronous ones are reported. → Analytical description is developed on the basis of the Watanabe-Strogatz approach.

Multi-Hop Link Capacity of Multi-Route Multi-Hop MRC Diversity for a Virtual Cellular Network

Science.gov (United States)

Daou, Imane; Kudoh, Eisuke; Adachi, Fumiyuki

In virtual cellular network (VCN), proposed for high-speed mobile communications, the signal transmitted from a mobile terminal is received by some wireless ports distributed in each virtual cell and relayed to the central port that acts as a gateway to the core network. In this paper, we apply the multi-route MHMRC diversity in order to decrease the transmit power and increase the multi-hop link capacity. The transmit power, the interference power and the link capacity are evaluated for DS-CDMA multi-hop VCN by computer simulation. The multi-route MHMRC diversity can be applied to not only DS-CDMA but also other access schemes (i. e. MC-CDMA, OFDM, etc.).

Vehicle to wireless power transfer coupling coil alignment sensor

Science.gov (United States)

Miller, John M.; Chambon, Paul H.; Jones, Perry T.; White, Clifford P.

2016-02-16

A non-contacting position sensing apparatus includes at least one vehicle-mounted receiver coil that is configured to detect a net flux null when the vehicle is optimally aligned relative to the primary coil in the charging device. Each of the at least one vehicle-mounted receiver coil includes a clockwise winding loop and a counterclockwise winding loop that are substantially symmetrically configured and serially connected to each other. When the non-contacting position sensing apparatus is located directly above the primary coil of the charging device, the electromotive forces from the clockwise winding loop and the counterclockwise region cancel out to provide a zero electromotive force, i.e., a zero voltage reading across the coil that includes the clockwise winding loop and the counterclockwise winding loop.

The Primordial Inflation Explorer (PIXIE): A Nulling Polarimeter for Cosmic Microwave Background Observations

Science.gov (United States)

Kogut, Alan J.; Fixsen, D. J.; Chuss, D. T.; Dotson, J.; Dwek, E.; Halpern, M.; Hinshaw, G. F.; Meyer, S. M.; Moseley, S. H.; Seiffert, M. D.;

The application of a multi-physics tool kit to spatial reactor dynamics

International Nuclear Information System (INIS)

Clifford, I.; Jasak, H.

2009-01-01

Traditionally coupled field nuclear reactor analysis has been carried out using several loosely coupled solvers, each having been developed independently from the others. In the field of multi-physics, the current generation of object-oriented tool kits provides robust close coupling of multiple fields on a single framework. This paper describes the initial results obtained as part of continuing research in the use of the OpenFOAM multi-physics tool kit for reactor dynamics application development. An unstructured, three-dimensional, time-dependent multi-group diffusion code Diffusion FOAM has been developed using the OpenFOAM multi-physics tool kit as a basis. The code is based on the finite-volume methodology and uses a newly developed block-coupled sparse matrix solver for the coupled solution of the multi-group diffusion equations. A description of this code is given with particular emphasis on the newly developed block-coupled solver, along with a selection of results obtained thus far. The code has performed well, indicating that the OpenFOAM tool kit is suited to reactor dynamics applications. This work has shown that the neutronics and simplified thermal-hydraulics of a reactor May be represented and solved for using a common calculation platform, and opens up the possibility for research into robust close-coupling of neutron diffusion and thermal-fluid calculations. This work has further opened up the possibility for research in a number of other areas, including research into three-dimensional unstructured meshes for reactor dynamics applications. (authors)

Optimal Scheduling of Biogas-Solar-Wind Renewable Portfolio for Multi-Carrier Energy Supplies

DEFF Research Database (Denmark)

Zhou, Bin; Xu, Da; Li, Canbing

2018-01-01

the mitigation of renewable intermittency and the efficient utilization of batteries, and a multi-carrier generation scheduling scheme is further presented to dynamically optimize dispatch factors in the coupling matrix for energy-efficient con-version and storage, while different energy demands of end......This paper proposes a multi-source multi-product framework for coupled multi-carrier energy supplies with a biogas-solar-wind hybrid renewable system. In this framework, the biogas-solar-wind complementarities are fully exploited based on digesting thermodynamic effects for the synergetic...... interactions of electricity, gas and heating energy flows, and a coupling matrix is formulated for the modeling of production, conversion, storage, and consumption of different energy carriers. The multi-energy complementarity of biogas-solar-wind renewable portfolio can be utilized to facilitate...

Modelling the electromechanical interactions in a null-flux EDS Maglev system

NARCIS (Netherlands)

Boeij, de J.; Steinbuch, M.; Gutierrez, H.M.; Fair, H.D.

2004-01-01

The fundamental electromechanical interactionsin a passive null-ux EDS maglev system aremediated by the voltages induced in the levita-tion coils by the sled magnets, and by the forcesexerted on the sled as a result of the inducedcurrents. This paper presents a reliable andcompact method to

What Constitutes Science and Scientific Evidence: Roles of Null Hypothesis Testing

Science.gov (United States)

Chang, Mark

2017-01-01

We briefly discuss the philosophical basis of science, causality, and scientific evidence, by introducing the hidden but most fundamental principle of science: the similarity principle. The principle's use in scientific discovery is illustrated with Simpson's paradox and other examples. In discussing the value of null hypothesis statistical…

Frequency of null allele of Human Leukocyte Antigen-G (HLA-G locus in subjects to recurrent miscarriage

Directory of Open Access Journals (Sweden)

Nazila Alizadeh

2016-07-01

Full Text Available Background: Human leukocyte antigen-G (HLA-G is a non-classical class I molecule highly expressed by extravillous cytotrophoblast cells. Due to a single base pair deletion, its function can be compensated by other isoforms. Investigating the frequency of null allele in Recurrent Miscarriage (RM subjects could be useful in understanding the relationship between frequency of this allele and RM in a given population. Objective: This study aimed to determine the frequency of HLA-G*0105N null allele and its potential association with down-regulation of HLA-G in subjects with RM. Materials and Methods: Western blotting was used to assess the level of HLA-G protein expression. For investigating the frequency of HLA-G*0105N null allele in RM subjects, PCR-RFLP method was used. Exon 3 of HLA-G gene was amplified by polymerase chain reaction (PCR. Subsequently, PpuM-1 enzyme was employed to digest the PCR products and fragments were analyzed using gel electrophoresis. Results: Digestion using restriction enzyme showed the presence of heterozygous HLA-G*0105N null allele in 10% of the test population. Western blotting results confirmed the decrease in expression of HLA-G in the placental tissue of subjects with RM compared to subjects who could give normal birth. Conclusion: The frequency of heterozygous HLA-G*0105N null allele was high to some extent in subjects with RM. The mutation rate in subjects suggested that there is a significant association between RM and frequency of mutations in this allele.

Frequency of null allele of Human Leukocyte Antigen-G (HLA-G) locus in subjects to recurrent miscarriage

Science.gov (United States)

Alizadeh, Nazila; Mosaferi, Elnaz; Farzadi, Laya; Majidi, Jafar; Monfaredan, Amir; Yousefi, Bahman; Baradaran, Behzad

2016-01-01

Background: Human leukocyte antigen-G (HLA-G) is a non-classical class I molecule highly expressed by extravillous cytotrophoblast cells. Due to a single base pair deletion, its function can be compensated by other isoforms. Investigating the frequency of null allele in Recurrent Miscarriage (RM) subjects could be useful in understanding the relationship between frequency of this allele and RM in a given population. Objective: This study aimed to determine the frequency of HLA-G*0105N null allele and its potential association with down-regulation of HLA-G in subjects with RM. Materials and Methods: Western blotting was used to assess the level of HLA-G protein expression. For investigating the frequency of HLA-G*0105N null allele in RM subjects, PCR-RFLP method was used. Exon 3 of HLA-G gene was amplified by polymerase chain reaction (PCR). Subsequently, PpuM-1 enzyme was employed to digest the PCR products and fragments were analyzed using gel electrophoresis. Results: Digestion using restriction enzyme showed the presence of heterozygous HLA-G*0105N null allele in 10% of the test population. Western blotting results confirmed the decrease in expression of HLA-G in the placental tissue of subjects with RM compared to subjects who could give normal birth. Conclusion: The frequency of heterozygous HLA-G*0105N null allele was high to some extent in subjects with RM. The mutation rate in subjects suggested that there is a significant association between RM and frequency of mutations in this allele. PMID:27525330

Multi-professional clinical medication reviews in care homes for the elderly: study protocol for a randomised controlled trial with cost effectiveness analysis

Directory of Open Access Journals (Sweden)

Sach Tracey

2011-10-01

Full Text Available Abstract Background Evidence demonstrates that measures are needed to optimise therapy and improve administration of medicines in care homes for older people. The aim of this study is to determine the clinical and cost effectiveness of a novel model of multi-professional medication review. Methods A cluster randomised controlled trial design, involving thirty care homes. In line with current practice in medication reviews, recruitment and consent will be sought from general practitioners and care homes, rather than individual residents. Care homes will be segmented according to size and resident mix and allocated to the intervention arm (15 homes or control arm (15 homes sequentially using minimisation. Intervention homes will receive a multi-professional medication review at baseline and at 6 months, with follow-up at 12 months. Control homes will receive usual care (support they currently receive from the National Health Service, with data collection at baseline and 12 months. The novelty of the intervention is a review of medications by a multi-disciplinary team. Primary outcome measures are number of falls and potentially inappropriate prescribing. Secondary outcome measures include medication costs, health care resource use, hospitalisations and mortality. The null hypothesis proposes no difference in primary outcomes between intervention and control patients. The primary outcome variable (number of falls will be analysed using a linear mixed model, with the intervention specified as a fixed effect and care homes included as a random effect. Analyses will be at the level of the care home. The economic evaluation will estimate the cost-effectiveness of the intervention compared to usual care from a National Health Service and personal social services perspective. The study is not measuring the impact of the intervention on professional working relationships, the medicines culture in care homes or the generic health-related quality of life of

Conformal gravity, the Einstein equations and spaces of complex null geodesics

Energy Technology Data Exchange (ETDEWEB)

Baston, R.J.; Mason, L.J.

1987-07-01

The aim of the paper is to give a twistorial characterisation of the field equations of conformal gravity and of Einstein spacetimes. Strong evidence is provided for a particularly concise characterisation of these equations in terms of 'formal neighbourhoods'of the space of complex null geodesics. Second-order perturbations of the metric of complexified Minkowski space are considered. These correspond to certain infinitesimal deformations of its space of complex null geodesics, PN. PN has a natural codimension one embedding into a larger space. It is shown that deformations extend automatically to the fourth-order embedding (that is, the fourth formal neighbourhood). They extend to the fifth formal neighbourhood if and only if the corresponding perturbation in the metric has vanishing Bach tensor. Finally, deformations which extend to the sixth formal neighbourhood correspond to perturbations in the metric that are conformally related to ones satisfying the Einstein equations. The authors present arguments which suggest that the results will also hold when spacetime is fully curved.

Conformal gravity, the Einstein equations and spaces of complex null geodesics

International Nuclear Information System (INIS)

Baston, R.J.; Mason, L.J.

1987-01-01

The aim of the paper is to give a twistorial characterisation of the field equations of conformal gravity and of Einstein spacetimes. Strong evidence is provided for a particularly concise characterisation of these equations in terms of 'formal neighbourhoods'of the space of complex null geodesics. Second-order perturbations of the metric of complexified Minkowski space are considered. These correspond to certain infinitesimal deformations of its space of complex null geodesics, PN. PN has a natural codimension one embedding into a larger space. It is shown that deformations extend automatically to the fourth-order embedding (that is, the fourth formal neighbourhood). They extend to the fifth formal neighbourhood if and only if the corresponding perturbation in the metric has vanishing Bach tensor. Finally, deformations which extend to the sixth formal neighbourhood correspond to perturbations in the metric that are conformally related to ones satisfying the Einstein equations. The authors present arguments which suggest that the results will also hold when spacetime is fully curved. (author)

Canonical theory of spherically symmetric spacetimes with cross-streaming null dusts

Science.gov (United States)

Bičák, Jiří; Hájíček, Petr

2003-11-01

The Hamiltonian dynamics of two-component spherically symmetric null dust is studied with regard to the quantum theory of gravitational collapse. The components—the ingoing and outgoing dusts—are assumed to interact only through gravitation. Different kinds of singularities, naked or “clothed,” which can form during collapse processes are described. The general canonical formulation of the one-component null-dust dynamics by Bičák and Kuchař is restricted to the spherically symmetric case and used to construct an action for the two components. The transformation from a metric variable to the quasilocal mass is shown to simplify the mathematics. The action is reduced by a choice of gauge and the corresponding true Hamiltonian is written down. Asymptotic coordinates and energy densities of dust shells are shown to form a complete set of Dirac observables. The action of the asymptotic time translation on the observables is defined but it has been calculated explicitly only in the case of one-component dust (Vaidya metric).

Control method for multi-input multi-output non-Gaussian random vibration test with cross spectra consideration

Directory of Open Access Journals (Sweden)

Ronghui ZHENG

2017-12-01

Full Text Available A control method for Multi-Input Multi-Output (MIMO non-Gaussian random vibration test with cross spectra consideration is proposed in the paper. The aim of the proposed control method is to replicate the specified references composed of auto spectral densities, cross spectral densities and kurtoses on the test article in the laboratory. It is found that the cross spectral densities will bring intractable coupling problems and induce difficulty for the control of the multi-output kurtoses. Hence, a sequential phase modification method is put forward to solve the coupling problems in multi-input multi-output non-Gaussian random vibration test. To achieve the specified responses, an improved zero memory nonlinear transformation is utilized first to modify the Fourier phases of the signals with sequential phase modification method to obtain one frame reference response signals which satisfy the reference spectra and reference kurtoses. Then, an inverse system method is used in frequency domain to obtain the continuous stationary drive signals. At the same time, the matrix power control algorithm is utilized to control the spectra and kurtoses of the response signals further. At the end of the paper, a simulation example with a cantilever beam and a vibration shaker test are implemented and the results support the proposed method very well. Keywords: Cross spectra, Kurtosis control, Multi-input multi-output, Non-Gaussian, Random vibration test

Randomizing growing networks with a time-respecting null model

Science.gov (United States)

Ren, Zhuo-Ming; Mariani, Manuel Sebastian; Zhang, Yi-Cheng; Medo, Matúš

2018-05-01

Complex networks are often used to represent systems that are not static but grow with time: People make new friendships, new papers are published and refer to the existing ones, and so forth. To assess the statistical significance of measurements made on such networks, we propose a randomization methodology—a time-respecting null model—that preserves both the network's degree sequence and the time evolution of individual nodes' degree values. By preserving the temporal linking patterns of the analyzed system, the proposed model is able to factor out the effect of the system's temporal patterns on its structure. We apply the model to the citation network of Physical Review scholarly papers and the citation network of US movies. The model reveals that the two data sets are strikingly different with respect to their degree-degree correlations, and we discuss the important implications of this finding on the information provided by paradigmatic node centrality metrics such as indegree and Google's PageRank. The randomization methodology proposed here can be used to assess the significance of any structural property in growing networks, which could bring new insights into the problems where null models play a critical role, such as the detection of communities and network motifs.

Non-dissipative electromagnetic media with two Lorentz null cones

International Nuclear Information System (INIS)

Dahl, Matias F.

2013-01-01

We study Maxwell’s equations on a 4-manifold where the electromagnetic medium is modeled by an antisymmetric (2/2 )-tensor with 21 real coefficients. In this setting the Fresnel surface is a fourth-order polynomial surface that describes the dynamical response of the medium in the geometric optics limit. For example, in an isotropic medium the Fresnel surface is a Lorentz null cone. The contribution of this paper is the pointwise description of all electromagnetic medium tensors κ with real coefficients that satisfy the following three conditions: (i)medium κ is invertible, (ii)medium κ is skewon-free, or non-dissipative, (iii)the Fresnel surface of κ is the union of two distinct Lorentz null cones. We show that there are only three classes of media with these properties and give explicit expressions in local coordinates for each class. - Highlights: ► We find two new electromagnetic media classes for which the Fresnel surface decomposes into two light cones. ► In a suitable setting we classify all electromagnetic media where this is the case. ► We find an electromagnetic medium tensor with three different signal speeds in one direction. ► The work is related to [5], which classifies all media with one light cone (in a suitable setting).

Radar Precoder Design for Spectral Coexistence with Coordinated Multi-point (CoMP) System

OpenAIRE

Mahal, Jasmin A.; Khawar, Awais; Abdelhadi, Ahmed; Clancy, T. Charles

2015-01-01

This paper details the design of precoders for a MIMO radar spectrally coexistent with a MIMO cellular network. We focus on a coordinated multi-point (CoMP) system where a cluster of base stations (BSs) coordinate their transmissions to the intended user. The radar operates in two modes, interference-mitigation mode when it avoids interference with the CoMP system and cooperation mode when it exchanges information with it. Using either the conventional Switched Null Space Projection (SNSP) or...

A Coding of Real Null Four-Momenta into World-Sheet Coordinates

Directory of Open Access Journals (Sweden)

David B. Fairlie

2009-01-01

Full Text Available The results of minimizing the action for string-like systems on a simply connected world sheet are shown to encode the Cartesian components of real null momentum four-vectors into coordinates on the world sheet. This identification arises consistently from different approaches to the problem.

Development of IR single mode optical fibers for DARWIN-nulling interferometry

NARCIS (Netherlands)

Chakkalakkal Abdulla, S.M.; Cheng, L.K.; Bosch, B. van den; Dijkhuizen, N.; Nieuwland, R.A.; Gielesen, W.L.M.; Lucas, J.; Boussard-Plédel, C.; Conseil, C.; Bureau, B.; Carmo, J.P. do

2014-01-01

The DARWIN mission aims to detect weak infra-red emission lines from distant orbiting earth-like planets using nulling interferometry. This requires filtering of wavefront errors using single mode waveguides operating at a wavelength range of 6.5-20 μm. This article describes the optical design of

CD4+CD28null T Cells are related to previous cytomegalovirus infection but not to accelerated atherosclerosis in ANCA-associated vasculitis.

Science.gov (United States)

Slot, Marjan C; Kroon, Abraham A; Damoiseaux, Jan G M C; Theunissen, Ruud; Houben, Alfons J H M; de Leeuw, Peter W; Tervaert, Jan Willem Cohen

2017-05-01

Previous studies have suggested an increased risk for cardiovascular events in antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV). We analyzed the presence of atherosclerotic damage in patients with AAV in relation to the presence of CD4 + CD28 null T cells and antibodies against cytomegalovirus (CMV) and human Heat-Shock Protein 60 (hHSP60). In this cross-sectional study, patients with inactive AAV were compared with healthy controls (HC). Carotid intima-media thickness (IMT) and aortic pulse-wave velocity (PWV) were measured. In addition, CD4 + CD28 null T cells, anti-CMV, and anti-hHSP60 levels were determined. Forty patients with AAV were included. Patients' spouses were recruited as HC (N = 38). CD4 + CD28 null T cells are present in patients with AAV in a higher percentage (median 3.1, range 0.01-85) than in HC (0.28, 0-36, P CD4 + CD28 null T cells (0.33 vs 13.8, P CD4 + CD28 null T cells and/or a previous CMV infection and IMT or PWV. There was no relation between anti-hHSP60 and CD4 + CD28 null T cells. Increased PWV values suggest atherosclerotic damage in patients with AAV. Plaque size, as determined by IMT, did not differ. CD4 + CD28 null T cells are increased in AAV and related to the previous CMV infection.

Multi-Periodic Photonic Crystal Out-Coupling Layers for Flexible OLEDs

DEFF Research Database (Denmark)

Kluge, Christian; Pradana, Arfat; Adam, Jost

2014-01-01

Waveguide mode extraction with multi-periodic photonic crystals is studied in experiment and finite-difference time-domain (FDTD) simulations. Flexible nanostructured organic light-emitting diodes (OLEDs) are fabricated by UV nanoimprint lithography.......Waveguide mode extraction with multi-periodic photonic crystals is studied in experiment and finite-difference time-domain (FDTD) simulations. Flexible nanostructured organic light-emitting diodes (OLEDs) are fabricated by UV nanoimprint lithography....

Null alleles and sequence variations at primer binding sites of STR loci within multiplex typing systems.

Science.gov (United States)

Yao, Yining; Yang, Qinrui; Shao, Chengchen; Liu, Baonian; Zhou, Yuxiang; Xu, Hongmei; Zhou, Yueqin; Tang, Qiqun; Xie, Jianhui

2018-01-01

Rare variants are widely observed in human genome and sequence variations at primer binding sites might impair the process of PCR amplification resulting in dropouts of alleles, named as null alleles. In this study, 5 cases from routine paternity testing using PowerPlex ® 21 System for STR genotyping were considered to harbor null alleles at TH01, FGA, D5S818, D8S1179, and D16S539, respectively. The dropout of alleles was confirmed by using alternative commercial kits AGCU Expressmarker 22 PCR amplification kit and AmpFℓSTR ® . Identifiler ® Plus Kit, and sequencing results revealed a single base variation at the primer binding site of each STR locus. Results from the collection of previous reports show that null alleles at D5S818 were frequently observed in population detected by two PowerPlex ® typing systems and null alleles at D19S433 were mostly observed in Japanese population detected by two AmpFℓSTR™ typing systems. Furthermore, the most popular mutation type appeared the transition from C to T with G to A, which might have a potential relationship with DNA methylation. Altogether, these results can provide helpful information in forensic practice to the elimination of genotyping discrepancy and the development of primer sets. Copyright © 2017 Elsevier B.V. All rights reserved.

No association of GSTM1 null polymorphism with endometriosis in women from central and southern Iran

Directory of Open Access Journals (Sweden)

Razieh Dehghani Firouzabadi

2012-01-01

Full Text Available Background: Endometriosis is one of the most common gynecologic disorders. It is a complex trait and both genetic and environmental factors have been implicated in its pathogenesis. There is growing evidence indicating that exposure to environmental contaminants is a risk factor for endometriosis. Glutathione-S-Transferase M1 (GSTM1 is one of the genes involved in detoxification of endogenous and exogenous compounds. Objective: Several studies have indicated an association between GSTM1 null mutation and endometriosis. In this study, the possible association between the GSTM1 gene null genotype and susceptibility to endometriosis in woman from central and southern Iran was investigated.Materials and Methods: One hundred and one unrelated premenopausal women with endometriosis and 142 unrelated healthy premenopausal women without endometriosis were enrolled in the study. Genomic DNA was extracted from Peripheral blood in all subjects. GSTM1 null genotyping was performed by polymerase chain reaction (PCR.Results: There was no significant difference between frequencies of GSTM1 null genotype in case and control groups (50.5% Vs. 52.1%, p=0.804. Furthermore, this genotype was not associated with severity of endometriosis in our sample (p=0.77. Conclusion: further studies involving gene-environment and gene-gene interactions, particularly combination of GSTM1 and other GST gene family polymorphisms are needed.

Non-minimally coupled tachyon and inflation

International Nuclear Information System (INIS)

Piao Yunsong; Huang Qingguo; Zhang Xinmin; Zhang Yuanzhong

2003-01-01

In this Letter, we consider a model of tachyon with a non-minimal coupling to gravity and study its cosmological effects. Regarding inflation, we show that only for a specific coupling of tachyon to gravity this model satisfies observations and solves various problems which exist in the single and multi tachyon inflation models. But noting in the string theory the coupling coefficient of tachyon to gravity is of order g s , which in general is very small, we can hardly expect that the non-minimally coupling of tachyon to gravity could provide a reasonable tachyon inflation scenario. Our work may be a meaningful try for the cosmological effect of tachyon non-minimally coupled to gravity

A Multi-Actor Dynamic Integrated Assessment Model (MADIAM)

OpenAIRE

Weber, Michael

2004-01-01

The interactions between climate and the socio-economic system are investigated with a Multi-Actor Dynamic Integrated Assessment Model (MADIAM) obtained by coupling a nonlinear impulse response model of the climate sub-system (NICCS) to a multi-actor dynamic economic model (MADEM). The main goal is to initiate a model development that is able to treat the dynamics of the coupled climate socio-economic system, including endogenous technological change, in a non-equilibrium situation, thereby o...

Reconfigurable Bandpass Sigma-Delta Modulator With Programmable NTF for Low-IF Multi-Mode Receivers

DEFF Research Database (Denmark)

Zhang, Ke; Mikkelsen, Jan H.; Shen, Ming

2012-01-01

transfer function of the loop while still maintaining stability. Compared with conventional multi-mode BPSDM, employing cascade structures and multi-bit sub-ADCs, the proposed modulator features many attractive advantages, such as (1) avoiding coefficient mismatch between analog and digital components...

Do electromagnetic waves always propagate along null geodesics?

International Nuclear Information System (INIS)

Asenjo, Felipe A; Hojman, Sergio A

2017-01-01

We find exact solutions to Maxwell equations written in terms of four-vector potentials in non–rotating, as well as in Gödel and Kerr spacetimes. We show that Maxwell equations can be reduced to two uncoupled second-order differential equations for combinations of the components of the four-vector potential. Exact electromagnetic waves solutions are written on given gravitational field backgrounds where they evolve. We find that in non–rotating spherical symmetric spacetimes, electromagnetic waves travel along null geodesics. However, electromagnetic waves on Gödel and Kerr spacetimes do not exhibit that behavior. (paper)

Null geodesic deviation II. Conformally flat space--times

International Nuclear Information System (INIS)

Peters, P.C.

1975-01-01

The equation of geodesic deviation is solved in conformally flat space--time in a covariant manner. The solution is given as an integral equation for general geodesics. The solution is then used to evaluate second derivatives of the world function and derivatives of the parallel propagator, which need to be known in order to find the Green's function for wave equations in curved space--time. A method of null geodesic limits of two-point functions is discussed, and used to find the scalar Green's function as an iterative series

Next generation GNSS single receiver cycle slip reliability

NARCIS (Netherlands)

Teunissen, P.J.G.; De Bakker, P.F.

2009-01-01

In this contribution we study the multi-frequency, carrier-phase slip detection capabilities of a single receiver. Our analysis is based on an analytical expression that we present for themulti-frequencyminimal detectable carrier phase cycle slip.

Multi-year predictability in a coupled general circulation model

Energy Technology Data Exchange (ETDEWEB)

Power, Scott; Colman, Rob [Bureau of Meteorology Research Centre, Melbourne, VIC (Australia)

2006-02-01

Multi-year to decadal variability in a 100-year integration of a BMRC coupled atmosphere-ocean general circulation model (CGCM) is examined. The fractional contribution made by the decadal component generally increases with depth and latitude away from surface waters in the equatorial Indo-Pacific Ocean. The relative importance of decadal variability is enhanced in off-equatorial ''wings'' in the subtropical eastern Pacific. The model and observations exhibit ''ENSO-like'' decadal patterns. Analytic results are derived, which show that the patterns can, in theory, occur in the absence of any predictability beyond ENSO time-scales. In practice, however, modification to this stochastic view is needed to account for robust differences between ENSO-like decadal patterns and their interannual counterparts. An analysis of variability in the CGCM, a wind-forced shallow water model, and a simple mixed layer model together with existing and new theoretical results are used to improve upon this stochastic paradigm and to provide a new theory for the origin of decadal ENSO-like patterns like the Interdecadal Pacific Oscillation and Pacific Decadal Oscillation. In this theory, ENSO-driven wind-stress variability forces internal equatorially-trapped Kelvin waves that propagate towards the eastern boundary. Kelvin waves can excite reflected internal westward propagating equatorially-trapped Rossby waves (RWs) and coastally-trapped waves (CTWs). CTWs have no impact on the off-equatorial sub-surface ocean outside the coastal wave guide, whereas the RWs do. If the frequency of the incident wave is too high, then only CTWs are excited. At lower frequencies, both CTWs and RWs can be excited. The lower the frequency, the greater the fraction of energy transmitted to RWs. This lowers the characteristic frequency of variability off the equator relative to its equatorial counterpart. Both the eastern boundary interactions and the accumulation of

Higher performance and lower cost optical DPSK receiver

Data.gov (United States)

National Aeronautics and Space Administration — To demonstrate (benchtop experiment) a DPSK receiver with a free-space interferometer, showing that fiber-optic coupling, associated adaptive optics, and optical...

Harmonically trapped attractive and repulsive spin–orbit and Rabi coupled Bose–Einstein condensates

International Nuclear Information System (INIS)

Chiquillo, Emerson

2017-01-01

Numerically we investigate the ground state of effective one-dimensional spin–orbit (SO) and Rabi coupled two pseudo-spinor Bose–Einstein condensates (BECs) under the effect of harmonic traps. For both signs of the interaction, density profiles of SO and Rabi coupled BECs in harmonic potentials, which simulate a real experimental situation are obtained. The harmonic trap causes a strong reduction of the multi-peak nature of the condensate and it increases its density. For repulsive interactions, the increase of SO coupling results in an uncompressed less dense condensate and with increased multi-peak nature of the density. The increase of Rabi coupling leads to a density increase with an almost constant number of multi-peaks. For both signs of the interaction and negative values of Rabi coupling, the condensate develops a notch in the central point and it seems to a dark-in-bright soliton. In the case of the attractive nonlinearity, an interesting result is the increase of the collapse threshold under the action of the SO and Rabi couplings. (paper)

High-energy scattering in strongly coupled N=4 super Yang-Mills theory

International Nuclear Information System (INIS)

Sprenger, Martin

2014-11-01