High poloidal beta equilibria in TFTR limited by a natural inboard poloidal field null
International Nuclear Information System (INIS)
Sabbagh, S.A.; Gross, R.A.; Mauel, M.E.; Navratil, G.A.; Bell, M.G.; Bell, R.; Bitter, M.; Bretz, N.L.; Budny, R.V.; Bush, C.E.; Chance, M.S.; Efthimion, P.C.; Fredrickson, E.D.; Hatcher, R.; Hawryluk, R.J.; Hirshman, S.P.; Janos, A.C.; Jardin, S.C.; Jassby, D.L.; Manickam, J.; McCune, D.C.; McGuire, K.M.; Medley, S.S.; Mueller, D.; Nagayama, Y.; Owens, D.K.; Okabayashi, M.; Park, H.K.; Ramsey, A.T.; Stratton, B.C.; Synakowski, E.J.; Taylor, G.; Wieland, R.M.; Zarnstorff, M.C.; Kesner, J.; Marmar, E.S.; Terry, J.L.
1991-07-01
Recent operation of the Tokamak Fusion Test Reactor TFTR, has produced plasma equilibria with values of Λ triple-bond β p eq + l i /2 as large as 7, εβ p dia triple-bond 2μ 0 ε /much-lt B p much-gt 2 as large as 1.6, and Troyon normalized diamagnetic beta, β N dia triple-bond 10 8 t perpendicular>aB 0 /I p as large as 4.7. When εβ p dia approx-gt 1.25, a separatrix entered the vacuum chamber, producing a naturally diverted discharge which was sustained for many energy confinement times, τ E . The largest values of εβ p and plasma stored energy were obtained when the plasma current was ramped down prior to neutral beam injection. The measured peak ion and electron temperatures were as large as 24 keV and 8.5 keV, respectively. Plasma stored energy in excess of 2.5 MJ and τ E greater than 130 msec were obtained. Confinement times of greater than 3 times that expected from L-mode predictions have been achieved. The fusion power gain. Q DD , reached a values of 1.3 x 10 -3 in a discharge with I p = 1 MA and εβ p dia = 0.85. A large, sustained negative loop voltage during the steady state portion of the discharge indicates that a substantial non-inductive component of I p exists in these plasmas. Transport code analysis indicates that the bootstrap current constitutes up to 65% of I p . Magnetohydrodynamic (MHD) ballooning stability analysis shows that while these plasmas are near, or at the β p limit, the pressure gradient in the plasma core is in the first region of stability to high-n modes. 24 refs., 10 figs
Directory of Open Access Journals (Sweden)
Jurczyk A
2013-12-01
Full Text Available Agata Jurczyk,1 Philip diIorio,1 Dean Brostowin,1 Linda Leehy,1 Chaoxing Yang,1 Fumihiko Urano,2 David M Harlan,3 Leonard D Shultz,4 Dale L Greiner,1 Rita Bortell1 1Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, 2Department of Medicine, Washington University School of Medicine, St Louis, MO, 3Department of Medicine, University of Massachusetts Medical School, Worcester, MA, 4The Jackson Laboratory, Bar Harbor, ME, USA Purpose: Dipeptidyl-peptidase-4 (DPP-4 inhibitors are known to increase insulin secretion and beta cell proliferation in rodents. To investigate the effects on human beta cells in vivo, we utilize immunodeficient mice transplanted with human islets. The study goal was to determine the efficacy of alogliptin, a DPP-4 inhibitor, to enhance human beta cell function and proliferation in an in vivo context using diabetic immunodeficient mice engrafted with human pancreatic islets. Methods: Streptozotocin-induced diabetic NOD-scid IL2rγnull (NSG mice were transplanted with adult human islets in three separate trials. Transplanted mice were treated daily by gavage with alogliptin (30 mg/kg/day or vehicle control. Islet graft function was compared using glucose tolerance tests and non-fasting plasma levels of human insulin and C-peptide; beta cell proliferation was determined by bromodeoxyuridine (BrdU incorporation. Results: Glucose tolerance tests were significantly improved by alogliptin treatment for mice transplanted with islets from two of the three human islet donors. Islet-engrafted mice treated with alogliptin also had significantly higher plasma levels of human insulin and C-peptide compared to vehicle controls. The percentage of insulin+BrdU+ cells in human islet grafts from alogliptin-treated mice was approximately 10-fold more than from vehicle control mice, consistent with a significant increase in human beta cell proliferation. Conclusion: Human islet-engrafted immunodeficient mice
Sarkar, Sailendra Nath; Bakshi, Sankar; Mokkapati, Sanath K; Roy, Sujit; Sengupta, Dibyendu N
2004-07-16
A single polypeptide with ddNTP-sensitive DNA polymerase activity was purified to near homogeneity from the shoot tips of rice seedlings and analysis of the preparations by SDS-PAGE followed by silver staining showed a polypeptide of 67 kDa size. The DNA polymerase activity was found to be inhibitory by ddNTP in both in vitro DNA polymerase activity assay and activity gel analysis. Aphidicolin, an inhibitor of other types of DNA polymerases, had no effect on plant enzyme. The 67 kDa rice DNA polymerase was found to be recognized by the polyclonal antibody (purified IgG) made against rat DNA polymerase beta (pol beta) both in solution and also on Western blot. The recognition was found to be very specific as the activity of Klenow enzyme was unaffected by the antibody. The ability of rice nuclear extract to correct G:U mismatch of oligo-duplex was observed when oligo-duplex with 32P-labeled lower strand containing U (at 22nd position) was used as substrate. Differential appearance of bands at 21-mer, 22-mer, and 51-mer position in presence of dCTP was visible only with G:U mismatch oligo-duplex, but not with G:C oligo-duplex. While ddCTP or polyclonal antibody against rat-DNA pol beta inhibits base excision repair (BER), aphidicolin had no effect. These results for the first time clearly demonstrate the ability of rice nuclear extract to run BER and the involvement of ddNTP-sensitive pol beta type DNA polymerase. Immunological similarity of the ddNTP-sensitive DNA polymerase beta of rice and rat and its involvement in BER revealed the conservation of structure and function of ddNTP-sensitive DNA pol beta in plant and animal.
Directory of Open Access Journals (Sweden)
Elena K Braithwaite
2010-08-01
Full Text Available Base excision repair (BER is a DNA repair pathway designed to correct small base lesions in genomic DNA. While DNA polymerase beta (pol beta is known to be the main polymerase in the BER pathway, various studies have implicated other DNA polymerases in back-up roles. One such polymerase, DNA polymerase lambda (pol lambda, was shown to be important in BER of oxidative DNA damage. To further explore roles of the X-family DNA polymerases lambda and beta in BER, we prepared a mouse embryonic fibroblast cell line with deletions in the genes for both pol beta and pol lambda. Neutral red viability assays demonstrated that pol lambda and pol beta double null cells were hypersensitive to alkylating and oxidizing DNA damaging agents. In vitro BER assays revealed a modest contribution of pol lambda to single-nucleotide BER of base lesions. Additionally, using co-immunoprecipitation experiments with purified enzymes and whole cell extracts, we found that both pol lambda and pol beta interact with the upstream DNA glycosylases for repair of alkylated and oxidized DNA bases. Such interactions could be important in coordinating roles of these polymerases during BER.
Holmes, Megan C; Abrahamsen, Christian T; French, Karen L; Paterson, Janice M; Mullins, John J; Seckl, Jonathan R
2006-04-05
Low birth weight associates with increased susceptibility to adult cardiometabolic and affective disorders spawning the notion of fetal "programming." Prenatal exposure to excess glucocorticoids may be causal. In support, maternal stress or treatment during pregnancy with dexamethasone (which crosses the placenta) or inhibitors of fetoplacental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the physiological "barrier" to maternal glucocorticoids, reduces birth weight and programs permanent offspring hypertension, hyperglycemia, and anxiety behaviors. It remains uncertain whether such effects are mediated indirectly via altered maternal function or directly on the fetus and its placenta. To dissect this critical issue, we mated 11beta-HSD2(+/-) mice such that each pregnant female produces +/+, +/-, and -/- offspring and compared them with offspring of homozygous wild-type and -/- matings. We show that 11beta-HSD2(-/-) offspring of either +/- or -/- mothers have lower birth weight and exhibit greater anxiety than 11beta-HSD2(+/+) littermates. This provides clear evidence for the key role of fetoplacental 11beta-HSD2 in prenatal glucocorticoid programming.
Yamada, H; Vijayachandra, K; Penner, C; Glick, A
2001-06-01
Inactivation of the transforming growth factor beta (TGFbeta)-signaling pathway and gene silencing through hypermethylation of promoter CpG islands are two frequent alterations in human and experimental cancers. Here we report that nonneoplastic TGFbeta1-/- keratinocyte cell lines exhibit increased sensitivity to cell killing by alkylating agents, and this is due to lack of expression of the DNA repair enzyme O(6)-methylguanine DNA methyltransferase (MGMT). In TGFbeta1-/- but not TGFbeta1+/- cell lines, the CpG dinucleotides in the MGMT promoter are hypermethylated, as measured by restriction enzyme analysis and methylation specific polymerase chain reaction. In one unstable TGFbeta1+/- cell line, loss of the wild type TGFbeta1 allele correlates with the appearance of methylation in the MGMT promoter. Bisulfite sequencing shows that in the KO3 TGFbeta1-/- cell line nearly all of the 28 CpG sites in the MGMT promoter 475 base pairs upstream of the start site of transcription are methylated, whereas most are unmethylated in the H1 TGFbeta1+/- line. Treatment of the TGFbeta1-/- cell lines with 5-azacytidine causes reexpression of MGMT mRNA and demethylation of CpG islands in the promoter. Analysis of the time course of methylation using methylation-specific polymerase chain reaction shows a lack of methylation in primary TGFbeta1-/- keratinocytes and increasing methylation with passage number of immortalized clones. Subcloning of early passage clones reveals a remarkable heterogeneity and instability of the methylation state in the TGFbeta1-/- keratinocytes. Thus, the TGFbeta1-/- genotype does not directly regulate MGMT methylation but predisposes cells to immortalization-associated MGMT hypermethylation.
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.)
Visible Nulling Coronagraph Progress Report
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.
Null lifts and projective dynamics
Energy Technology Data Exchange (ETDEWEB)
Cariglia, Marco, E-mail: marco@iceb.ufop.br
2015-11-15
We describe natural Hamiltonian systems using projective geometry. The null lift procedure endows the tangent bundle with a projective structure where the null Hamiltonian is identified with a projective conic and induces a Weyl geometry. Projective transformations generate a set of known and new dualities between Hamiltonian systems, as for example the phenomenon of coupling-constant metamorphosis. We conclude outlining how this construction can be extended to the quantum case for Eisenhart–Duval lifts.
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.
Bare Quantum Null Energy Condition.
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.
Visible nulling coronagraph testbed results
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.
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.
Gastrointestinal hyperplasia with altered expression of DNA polymerase beta.
Directory of Open Access Journals (Sweden)
Katsuhiko Yoshizawa
2009-08-01
Full Text Available Altered expression of DNA polymerase beta (Pol beta has been documented in a large percentage of human tumors. However, tumor prevalence or predisposition resulting from Pol beta over-expression has not yet been evaluated in a mouse model.We have recently developed a novel transgenic mouse model that over-expresses Pol beta. These mice present with an elevated incidence of spontaneous histologic lesions, including cataracts, hyperplasia of Brunner's gland and mucosal hyperplasia in the duodenum. In addition, osteogenic tumors in mice tails, such as osteoma and osteosarcoma were detected. This is the first report of elevated tumor incidence in a mouse model of Pol beta over-expression. These findings prompted an evaluation of human gastrointestinal tumors with regard to Pol beta expression. We observed elevated expression of Pol beta in stomach adenomas and thyroid follicular carcinomas, but reduced Pol beta expression in esophageal adenocarcinomas and squamous carcinomas.These data support the hypothesis that balanced and proficient base excision repair protein expression and base excision repair capacity is required for genome stability and protection from hyperplasia and tumor formation.
The Importance of Proving the Null
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…
International Nuclear Information System (INIS)
Borovikov, N.V.; Kosinov, G.A.; Fedorov, Yu.N.
1989-01-01
Portable transportable digital beta radiometer providing for measuring beta-decay radionuclide specific activity in the range from 5x10 -9 up to 10 -6 Cu/kg (Cu/l) with error of ±25% is designed and introduced into commercial production for determination of volume and specific water and food radioactivity. The device specifications are given. Experience in the BETA radiometer application under conditions of the Chernobyl' NPP 30-km zone has shown that it is convenient for measuring specific activity of the order of 10 -8 Cu/kg, and application of a set of different beta detectors gives an opportunity to use it for surface contamination measurement in wide range of the measured value
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
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.)
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
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
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
High-contrast Nulling Interferometry Techniques Project
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,...
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
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)
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...
Beta 1 integrin is essential for teratoma growth and angiogenesis
DEFF Research Database (Denmark)
Bloch, W; Forsberg, E; Lentini, S
1997-01-01
Teratomas are benign tumors that form after ectopic injection of embryonic stem (ES) cells into mice and contain derivatives of all primitive germ layers. To study the role of beta 1 integrin during teratoma formation, we compared teratomas induced by normal and beta1-null ES cells. Injection of ...
Genetic analysis of beta1 integrin "activation motifs" in mice
DEFF Research Database (Denmark)
Czuchra, Aleksandra; Meyer, Hannelore; Legate, Kyle R
2006-01-01
-null phenotype in vivo. Surprisingly, neither the substitution of the tyrosines with phenylalanine nor the aspartic acid with alanine resulted in an obvious defect. These data suggest that the NPXY motifs of the beta1 integrin tail are essential for beta1 integrin function, whereas tyrosine phosphorylation...
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.
Supersymmetric null-like holographic cosmologies
International Nuclear Information System (INIS)
Lin Fengli; Wen Wenyu
2006-01-01
We construct a new class of 1/4-BPS time dependent domain-wall solutions with null-like metric and dilaton in type II supergravities, which admit a null-like big bang singularity. Based on the domain-wall/QFT correspondence, these solutions are dual to 1/4-supersymmetric quantum field theories living on a boundary cosmological background with time dependent coupling constant and UV cutoff. In particular we evaluate the holographic c function for the 2-dimensional dual field theory living on the corresponding null-like cosmology. We find that this c function runs in accordance with the c-theorem as the boundary universe evolves, this means that the number of degrees of freedom is divergent at big bang and suggests the possible resolution of big bang singularity
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
Fine art of computing nulling interferometer maps
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.
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
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
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
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.)
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 .
Harrison Hong; David Sraer
2012-01-01
We provide a model for why high beta assets are more prone to speculative overpricing than low beta ones. When investors disagree about the common factor of cash-flows, high beta assets are more sensitive to this macro-disagreement and experience a greater divergence-of-opinion about their payoffs. Short-sales constraints for some investors such as retail mutual funds result in high beta assets being over-priced. When aggregate disagreement is low, expected return increases with beta due to r...
Copani, Agata; Hoozemans, Jeroen J. M.; Caraci, Filippo; Calafiore, Marco; van Haastert, Elise S.; Veerhuis, Robert; Rozemuller, Annemieke J. M.; Aronica, Eleonora; Sortino, Maria Angela; Nicoletti, Ferdinando
2006-01-01
Cultured neurons exposed to synthetic beta-amyloid (Abeta) fragments reenter the cell cycle and initiate a pathway of DNA replication that involves the repair enzyme DNA polymerase-beta (DNA pol-beta) before undergoing apoptotic death. In this study, by performing coimmunoprecipitation experiments
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.
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
Collapse and bounce of null fluids
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)
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;.
DNA polymerase beta participates in mitochondrial DNA repair
DEFF Research Database (Denmark)
Sykora, P; Kanno, S; Akbari, M
2017-01-01
We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments, mitocho......We have detected DNA polymerase beta (Polβ), known as a key nuclear base excision repair (BER) protein, in mitochondrial protein extracts derived from mammalian tissue and cells. Manipulation of the N-terminal sequence affected the amount of Polβ in the mitochondria. Using Polβ fragments......, mitochondrial-specific protein partners were identified, with the interactors mainly functioning in DNA maintenance and mitochondrial import. Of particular interest was the identification of the proteins TWINKLE, SSBP1 and TFAM, all of which are mitochondria specific DNA effectors and are known to function...... in the nucleoid. Polβ directly interacted with, and influenced the activity of, the mitochondrial helicase TWINKLE. Human kidney cells with Polβ knock-out (KO) had higher endogenous mtDNA damage. Mitochondrial extracts derived from heterozygous Polβ mouse tissue and KO cells had lower nucleotide incorporation...
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)
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
Dall-Null tester for spaceborne applications
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.
Averaged null energy condition from causality
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.
Recent developments with the visible nulling coronagraph
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.
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
International Nuclear Information System (INIS)
Dryak, P.; Zderadicka, J.; Plch, J.; Kokta, L.; Novotna, P.
1977-01-01
For the purpose of beta spectrometry, a semiconductor spectrometer with one Si(Li) detector cooled with liquid nitrogen was designed. Geometrical detection efficiency is about 10% 4 sr. The achieved resolution for 624 keV conversion electrons of sup(137m)Ba is 2.6 keV (FWHM). A program was written in the FORTRAN language for the correction of the deformation of the measured spectra by backscattering in the analysis of continuous beta spectra. The method permits the determination of the maximum energy of the beta spectrum with an accuracy of +-5 keV. (author)
... may not work as effectively for people of African heritage and older people, especially when taken without ... conditions/high-blood-pressure/in-depth/beta-blockers/ART-20044522 . Mayo Clinic Footer Legal Conditions and Terms ...
Impaired insulin secretion and glucose intolerance in synaptotagmin-7 null mutant mice
DEFF Research Database (Denmark)
Gustavsson, Natalia; Lao, Ye; Maximov, Anton
2008-01-01
and insulin release. Here, we show that synaptotagmin-7 is required for the maintenance of systemic glucose tolerance and glucose-stimulated insulin secretion. Mutant mice have normal insulin sensitivity, insulin production, islet architecture and ultrastructural organization, and metabolic and calcium...... secretion in pancreatic beta-cells. Of these other synaptotagmins, synaptotagmin-7 is one of the most abundant and is present in pancreatic beta-cells. To determine whether synaptotagmin-7 regulates Ca(2+)-dependent insulin secretion, we analyzed synaptotagmin-7 null mutant mice for glucose tolerance...... responses but exhibit impaired glucose-induced insulin secretion, indicating a calcium-sensing defect during insulin-containing secretory granule exocytosis. Taken together, our findings show that synaptotagmin-7 functions as a positive regulator of insulin secretion and may serve as a calcium sensor...
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.
Technology Advancement of the Visible Nulling Coronagraph
Lyon, Richard G.; Clampin, Mark; Petrone, Peter; Thompson, Patrick; Bolcar, Matt; Madison, Timothy; Woodruff, Robert; Noecker, Charley; Kendrick, Steve
2010-01-01
The critical high contrast imaging technology for the Extrasolar Planetary Imaging Coronagraph (EPIC) mission concept is the visible nulling coronagraph (VNC). EPIC would be capable of imaging jovian planets, dust/debris disks, and potentially super-Earths and contribute to answering how bright the debris disks are for candidate stars. The contrast requirement for EPIC is 10(exp 9) contrast at 125 milli-arseconds inner working angle. To advance the VNC technology NASA/Goddard Space Flight Center, in collaboration with Lockheed-Martin, previously developed a vacuum VNC testbed, and achieved narrowband and broadband suppression of the core of the Airy disk. Recently our group was awarded a NASA Technology Development for Exoplanet Missions to achieve two milestones: (i) 10(exp 8) contrast in narrowband light, and, (ii) 10(ecp 9) contrast in broader band light; one milestone per year, and both at 2 Lambda/D inner working angle. These will be achieved with our 2nd generation testbed known as the visible nulling testbed (VNT). It contains a MEMS based hex-packed segmented deformable mirror known as the multiple mirror array (MMA) and coherent fiber bundle, i.e. a spatial filter array (SFA). The MMA is in one interferometric arm and works to set the wavefront differences between the arms to zero. Each of the MMA segments is optically mapped to a single mode fiber of the SFA, and the SFA passively cleans the sub-aperture wavefront error leaving only piston, tip and tilt error to be controlled. The piston degree of freedom on each segment is used to correct the wavefront errors, while the tip/tilt is used to simultaneously correct the amplitude errors. Thus the VNT controls both amplitude and wavefront errors with a single MMA in closed-loop in a vacuum tank at approx.20 Hz. Herein we will discuss our ongoing progress with the VNT.
[Dilemma of null hypothesis in ecological hypothesis's experiment test.
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.
Broadband Active Segmented Aperture and Radial Shear Nulling
National Aeronautics and Space Administration — The Visible Nulling Coronagraph (VNC) is a starlight suppression system for enabling exoplanet detectionand atmospheric measurement. Conceptual space telescope...
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
Visual and Plastic Arts in Teaching Literacy: Null Curricula?
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…
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 ...
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)
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.
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.
A new dynamic null model for phylogenetic community structure
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
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
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.)
An omnibus test for the global null hypothesis.
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.
The Visible Nulling Coronagraph--Architecture Definition and Technology Development
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;
2005-01-01
This paper describes the advantages of visible direct detection and spectroscopy of Earth-like extrasolar planets using a nulling coronagraph instrument behind a moderately sized single aperture space telescope. Our concept synthesizes a nulling interferometer by shearing the telescope pupil, with the resultant producing a deep null. We describe nulling configurations that also include methods to mitigate stellar leakage, such as spatial filtering by a coherent array of single mode fibers, and post-starlight suppression wavefront sensing and control. With diffraction limited telescope optics and similar quality components in the optical train (lambda/20), suppression of the starlight to 1e-10 is readily achievable. We describe key features of the architecture and analysis, present latest results of laboratory measurements demonstrating achievable null depth and component development, and discuss future key technical milestones.
Wormholes minimally violating the null energy condition
Energy Technology Data Exchange (ETDEWEB)
Bouhmadi-López, Mariam [Departamento de Física, Universidade da Beira Interior, 6200 Covilhã (Portugal); Lobo, Francisco S N; Martín-Moruno, Prado, E-mail: mariam.bouhmadi@ehu.es, E-mail: fslobo@fc.ul.pt, E-mail: pmmoruno@fc.ul.pt [Centro de Astronomia e Astrofísica da Universidade de Lisboa, Campo Grande, Edifício C8, 1749-016 Lisboa (Portugal)
2014-11-01
We consider novel wormhole solutions supported by a matter content that minimally violates the null energy condition. More specifically, we consider an equation of state in which the sum of the energy density and radial pressure is proportional to a constant with a value smaller than that of the inverse area characterising the system, i.e., the area of the wormhole mouth. This approach is motivated by a recently proposed cosmological event, denoted {sup t}he little sibling of the big rip{sup ,} where the Hubble rate and the scale factor blow up but the cosmic derivative of the Hubble rate does not [1]. By using the cut-and-paste approach, we match interior spherically symmetric wormhole solutions to an exterior Schwarzschild geometry, and analyse the stability of the thin-shell to linearized spherically symmetric perturbations around static solutions, by choosing suitable properties for the exotic material residing on the junction interface radius. Furthermore, we also consider an inhomogeneous generalization of the equation of state considered above and analyse the respective stability regions. In particular, we obtain a specific wormhole solution with an asymptotic behaviour corresponding to a global monopole.
Bodyweight Assessment of Enamelin Null Mice
Directory of Open Access Journals (Sweden)
Albert H.-L. Chan
2013-01-01
Full Text Available The Enam null mice appear to be smaller than wild-type mice, which prompted the hypothesis that enamel defects negatively influence nutritional intake and bodyweight gain (BWG. We compared the BWG of Enam−/− and wild-type mice from birth (D0 to Day 42 (D42. Wild-type (WT and Enam−/− (N mice were given either hard chow (HC or soft chow (SC. Four experimental groups were studied: WTHC, WTSC, NHC, and NSC. The mother’s bodyweight (DBW and the average litter bodyweight (ALBW were obtained from D0 to D21. After D21, the pups were separated from the mother and provided the same type of food. Litter bodyweights were measured until D42. ALBW was compared at 7-day intervals using one-way ANOVA, while the influence of DBW on ALBW was analyzed by mixed-model analyses. The ALBW of Enam−/− mice maintained on hard chow (NHC was significantly lower than the two WT groups at D21 and the differences persisted into young adulthood. The ALBW of Enam−/− mice maintained on soft chow (NSC trended lower, but was not significantly different than that of the WT groups. We conclude that genotype, which affects enamel integrity, and food hardness influence bodyweight gain in postnatal and young adult mice.
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
DEFF Research Database (Denmark)
Mulder, Hindrik; Sörhede-Winzell, Maria; Contreras, Juan Antonio
2003-01-01
of increased amounts of insulin. Impaired insulin sensitivity was further indicated by retarded glucose disposal during an insulin tolerance test. A euglycemic hyperinsulinemic clamp revealed that hepatic glucose production was insufficiently blocked by insulin in HSL null mice. In vitro, insulin......-stimulated glucose uptake into soleus muscle, and lipogenesis in adipocytes were moderately reduced, suggesting additional sites of insulin resistance. Morphometric analysis of pancreatic islets revealed a doubling of beta-cell mass in HSL null mice, which is consistent with an adaptation to insulin resistance....... Insulin secretion in vitro, examined by perifusion of isolated islets, was not impacted by HSL deficiency. Thus, HSL deficiency results in a moderate impairment of insulin sensitivity in multiple target tissues of the hormone but is compensated by hyperinsulinemia....
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.
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 ...
Dysregulation of Dicer1 in Beta Cells Impairs Islet Architecture and Glucose Metabolism
Directory of Open Access Journals (Sweden)
Amitai D. Mandelbaum
2012-01-01
Full Text Available microRNAs (miRNAs play important roles in pancreas development and in regulation of insulin expression in the adult. Here we show that loss of miRNAs activity in beta-cells during embryonic development results in lower beta-cell mass and in impaired glucose tolerance. Dicer1-null cells initially constitute a significant portion of the total beta-cell population. However, during postnatal development, Dicer1-null cells are depleted. Furthermore, wild-type beta cells are repopulating the islets in complex compensatory dynamics. Because loss of Dicer1 is also associated with changes in the distribution of membranous E-cadherin, we hypothesized that E-cadherin activity may play a role in beta cell survival or islet architecture. However, genetic loss of E-cadherin function does not impair islet architecture, suggesting that miRNAs likely function through other or redundant effectors in the endocrine pancreas.
Lack of beta1 integrins in enteric neural crest cells leads to a Hirschsprung-like phenotype
DEFF Research Database (Denmark)
Breau, Marie A; Pietri, Thomas; Eder, Olivier
2006-01-01
The enteric nervous system arises mainly from vagal and sacral neural crest cells that colonise the gut between 9.5 and 14 days of development in mice. Using the Cre-LoxP system, we removed beta1 integrins in the neural crest cells when they emerge from the neural tube. beta1-null enteric neural...
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 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.
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
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)
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.)
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.
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)
Metastable beta limit in DIII-D
International Nuclear Information System (INIS)
La Haye, R.J.; Callen, J.D.; Gianakon, T.A.
1997-06-01
The long-pulse, slowly evolving single-null divertor (SND) discharges in DIII-D with H-mode, ELMs, and sawteeth are found to be limited significantly below (factor of 2) the predicted ideal limit β N = 4l i by the onset of tearing modes. The tearing modes are metastable in that they are explained by the neoclassical bootstrap current (high β θ ) destabilization of a seed island which occurs even if Δ' θ , there is a region of the modified Rutherford equation such that dw/dt > 0 for w larger than a threshold value; the plasma is metastable, awaiting the critical perturbation which is then amplified to the much larger saturated island. Experimental results from a large number of tokamaks indicate that the high beta operational envelope of the tokamak is well defined by ideal magnetohydrodynamic (MHD) theory. The highest beta values achieved have historically been obtained in fairly short pulse discharges, often <1-2 sawteeth periods and < 1-2 energy replacement times. The maximum operational beta in single-null divertor (SND), long-pulse discharges in DIII-D with a cross-sectional shape similar to the proposed ITER tokamak is found to be limited significantly below the threshold for ideal instabilities by the onset of resistive MHD instabilities
Nulling Data Reduction and On-Sky Performance of the Large Binocular Telescope Interferometer
Defrere, D.; Hinz, P. M.; Mennesson, B.; Hoffman, W. F.; Millan-Gabet, R.; Skemer, A. J.; Bailey, V.; Danchi, W. C.; Downy, E. C.; Durney, O.;
2016-01-01
The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high angular resolution and high-contrast infrared imaging (1.5-13 micrometers). In this paper, we focus on the mid-infrared (8-13 micrometers) nulling mode and present its theory of operation, data reduction, and on-sky performance as of the end of the commissioning phase in 2015 March. With an interferometric baseline of 14.4 m, the LBTI nuller is specifically tuned to resolve the habitable zone of nearby main-sequence stars, where warm exozodiacal dust emission peaks. Measuring the exozodi luminosity function of nearby main-sequence stars is a key milestone to prepare for future exo-Earth direct imaging instruments. Thanks to recent progress in wavefront control and phase stabilization, as well as in data reduction techniques, the LBTI demonstrated in 2015 February a calibrated null accuracy of 0.05% over a 3 hr long observing sequence on the bright nearby A3V star Beta Leo. This is equivalent to an exozodiacal disk density of 15-30 zodi for a Sun-like star located at 10 pc, depending on the adopted disk model. This result sets a new record for high-contrast mid-infrared interferometric imaging and opens a new window on the study of planetary systems.
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
Evaluation of null-point detection methods on simulation data
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.
Visible nulling coronagraphy testbed development for exoplanet detection
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.
Tolerance analysis of null lenses using an end-use system performance criterion
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.
Null but not void: considerations for hypothesis testing.
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.
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
Unicorns do exist: a tutorial on "proving" the null hypothesis.
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.
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.
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.)
Ideal MHD beta-limits of poloidally asymmetric equilibria
Energy Technology Data Exchange (ETDEWEB)
Todd, A.M.M.; Miller, A.E.; Grimm, R.C.; Okabayashi, M.; Dalhed, H.E. Jr.
1981-05-01
The ideal MHD stability of poloidally asymmetric equilibria, which are typical of a tokamak reactor design with a single-null poloidal divertor is examined. As with symmetric equilibria, stability to non-axisymmetric modes improves with increasing triangularity and ellipticity, and with lower edge safety factor. Pressure profiles optimized with respect to ballooning stability are obtained for an asymmetric shape, resulting in ..beta../sub critical/ approx. = 5.7%. The corresponding value for an equivalent symmetric shape is ..beta../sub critical/ approx. = 6.5%.
Chemical rescue of cleft palate and midline defects in conditional GSK-3beta mice.
Liu, Karen J; Arron, Joseph R; Stankunas, Kryn; Crabtree, Gerald R; Longaker, Michael T
2007-03-01
Glycogen synthase kinase-3beta (GSK-3beta) has integral roles in a variety of biological processes, including development, diabetes, and the progression of Alzheimer's disease. As such, a thorough understanding of GSK-3beta function will have a broad impact on human biology and therapeutics. Because GSK-3beta interacts with many different pathways, its specific developmental roles remain unclear. We have discovered a genetic requirement for GSK-3beta in midline development. Homozygous null mice display cleft palate, incomplete fusion of the ribs at the midline and bifid sternum as well as delayed sternal ossification. Using a chemically regulated allele of GSK-3beta (ref. 6), we have defined requirements for GSK-3beta activity during discrete temporal windows in palatogenesis and skeletogenesis. The rapamycin-dependent allele of GSK-3beta produces GSK-3beta fused to a tag, FRB* (FKBP/rapamycin binding), resulting in a rapidly destabilized chimaeric protein. In the absence of drug, GSK-3beta(FRB)*(/FRB)* mutants appear phenotypically identical to GSK-3beta-/- mutants. In the presence of drug, GSK-3betaFRB* is rapidly stabilized, restoring protein levels and activity. Using this system, mutant phenotypes were rescued by restoring endogenous GSK-3beta activity during two distinct periods in gestation. This technology provides a powerful tool for defining windows of protein function during development.
Beta Emission and Bremsstrahlung
Energy Technology Data Exchange (ETDEWEB)
Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-11-13
Bremsstrahlung is continuous radiation produced by beta particles decelerating in matter; different beta emitters have different endpoint energies; high-energy betas interacting with high-Z materials will more likely produce bremsstrahlung; depending on the data, sometimes all you can say is that a beta emitter is present.
Testing the null hypothesis: the forgotten legacy of Karl Popper?
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.
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 ...
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 ...
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
The Many Null Distributions of Person Fit Indices.
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)
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
Red hair is the null phenotype of MC1R.
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.
On the null distribution of Bayes factors in linear regression
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...
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...
Null point of discrimination in crustacean polarisation vision.
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.
Null Lens Assembly for X-Ray Mirror Segments
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.
Self-Nulling Beam Combiner Using No External Phase Inverter
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.
Visible Nulling Coronagraphy for Exo-Planetary Detection and Characterization
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.
Shaping Up the Practice of Null Hypothesis Significance Testing.
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…
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] ...
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
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
An AP endonuclease 1-DNA polymerase beta complex: theoretical prediction of interacting surfaces.
Directory of Open Access Journals (Sweden)
Alexej Abyzov
2008-04-01
Full Text Available Abasic (AP sites in DNA arise through both endogenous and exogenous mechanisms. Since AP sites can prevent replication and transcription, the cell contains systems for their identification and repair. AP endonuclease (APEX1 cleaves the phosphodiester backbone 5' to the AP site. The cleavage, a key step in the base excision repair pathway, is followed by nucleotide insertion and removal of the downstream deoxyribose moiety, performed most often by DNA polymerase beta (pol-beta. While yeast two-hybrid studies and electrophoretic mobility shift assays provide evidence for interaction of APEX1 and pol-beta, the specifics remain obscure. We describe a theoretical study designed to predict detailed interacting surfaces between APEX1 and pol-beta based on published co-crystal structures of each enzyme bound to DNA. Several potentially interacting complexes were identified by sliding the protein molecules along DNA: two with pol-beta located downstream of APEX1 (3' to the damaged site and three with pol-beta located upstream of APEX1 (5' to the damaged site. Molecular dynamics (MD simulations, ensuring geometrical complementarity of interfaces, enabled us to predict interacting residues and calculate binding energies, which in two cases were sufficient (approximately -10.0 kcal/mol to form a stable complex and in one case a weakly interacting complex. Analysis of interface behavior during MD simulation and visual inspection of interfaces allowed us to conclude that complexes with pol-beta at the 3'-side of APEX1 are those most likely to occur in vivo. Additional multiple sequence analyses of APEX1 and pol-beta in related organisms identified a set of correlated mutations of specific residues at the predicted interfaces. Based on these results, we propose that pol-beta in the open or closed conformation interacts and makes a stable interface with APEX1 bound to a cleaved abasic site on the 3' side. The method described here can be used for analysis in
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
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
Taladriz, Soraya; Hanke, Tobias; Ramiro, María J.; García-Díaz, Miguel; Lacoba, Mario García de; Blanco, Luis; Larraga, Vicente
2001-01-01
We have identified a novel polymerase beta (Pol β)-like enzyme from Leishmania infantum, a parasite protozoon causing disease in humans. This protein, named Li Pol β, shows a nuclear localization that contrasts with the mitochondrial localization of Pol β from Crithidia fasciculata, a closely related parasite, the only polymerase β described so far in Trypanosomatidae. Li Pol β, that belongs to the DNA polymerase X family, displays an evolutionarily conserved Pol β-type DNA polymerase core, in which most of the key residues involved in DNA binding, nucleotide binding, dRPase and polymerization catalysis are conserved. In agreement with this, Li Pol β, overproduced in Escherichia coli, displayed intrinsic DNA polymerase activity. Cell synchronization experiments showed a correlation between both Li Pol β mRNA and protein levels along the parasite cell cycle. Analysis of these parameters at the different growth phases of the parasite, from the proliferative (non-infective) logarithmic phase to the non-dividing (highly infectious) stationary phase, showed high levels of Li Pol β at the infective phase of the parasite. The data suggest a role of Li Pol β in base excision repair in L.infantum, a parasite usually affected by oxygen stress environments into the macrophage host cells. PMID:11557814
Detection of long nulls in PSR B1706-16, a pulsar with large timing irregularities
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.
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
Local modular Hamiltonians from the quantum null energy condition
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 .
Segmented Aperture Interferometric Nulling Testbed (SAINT) II: component systems update
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.
DEFF Research Database (Denmark)
Gimond, C; van Der Flier, A; van Delft, S
1999-01-01
different beta1-null cell lines, epithelial GE11 and fibroblast-like GD25 cells. Expression of beta1A or the cytoplasmic splice variant beta1D, induced the disruption of intercellular adherens junctions and cell scattering in both GE11 and GD25 cells. In GE11 cells, the morphological change correlated...... for a complete morphological transition towards the spindle-shaped fibroblast-like phenotype. The expression of an interleukin-2 receptor (IL2R)-beta1A chimera and its incorporation into focal adhesions also induced the disruption of cadherin-based adhesions and the reorganization of ECM-cell contacts...
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
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.
The quantum null energy condition in curved space
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.
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.
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
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)
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
In Search of the Null: The NCSA 2003 Presidential Address
Directory of Open Access Journals (Sweden)
Beth Davison
2003-10-01
Full Text Available Sociologists usually publish articles where the results show statistically significant differences between two groups of people. Results which show the opposite are generally called 'negative findings,' and are not considered publishable. Davison argues that we really ought to be looking for and encouraging the null finding, especially when social inequality and poverty are the issue. In addition, society as a whole should be working to eliminate poverty and inequality
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.)
The Quantum Focussing Conjecture and Quantum Null Energy Condition
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.)
PERSEE: a nulling interferometer with dynamic correction of external perturbations
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.
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)
"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.
DEFF Research Database (Denmark)
Potocnik, A J; Brakebusch, C; Fässler, R
2000-01-01
hematolymphoid differentiation potential in vitro and in fetal organ cultures but were unable to seed fetal and adult hematopoietic tissues. Adult beta1 integrin null HSCs isolated from mice carrying loxP-tagged beta1 integrin alleles and ablated for beta1 integrin expression by retroviral cre transduction......Homing of hematopoietic stem cells (HSCs) into hematopoietic organs is a prerequisite for the establishment of hematopoiesis during embryogenesis and after bone marrow transplantation. We show that beta1 integrin-deficient HSCs from the para-aortic splanchnopleura and the fetal blood had...
Fernandez, Pablo
2003-01-01
We prove that in a world without leverage cost the relationship between the levered beta ( L) and the unlevered beta ( u) is the No-costs-of-leverage formula: L = u + ( u - d) D (1 - T) / E. We also analyze 6 alternative valuation theories proposed in the literature to estimate the relationship between the levered beta and the unlevered beta (Harris and Pringle (1985), Modigliani and Miller (1963), Damodaran (1994), Myers (1974), Miles and Ezzell (1980), and practitioners) and prove that all ...
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.)
Left cardiac isomerism in the Sonic hedgehog null mouse.
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
Beta Thalassemia (For Parents)
... Safe Videos for Educators Search English Español Beta Thalassemia KidsHealth / For Parents / Beta Thalassemia What's in this ... Symptoms Diagnosis Treatment Print en español Beta talasemia Thalassemias Thalassemias are a group of blood disorders that ...
Searches for massive neutrinos in nuclear beta decay
International Nuclear Information System (INIS)
Jaros, J.A.
1992-10-01
The status of searches for massive neutrinos in nuclear beta decay is reviewed. The claim by an ITEP group that the electron antineutrino mass > 17eV has been disputed by all the subsequent experiments. Current measurements of the tritium beta spectrum limit m bar νe < 10 eV. The status of the 17 keV neutrino is reviewed. The strong null results from INS Tokyo and Argonne, and deficiencies in the experiments which reported positive effects, make it unreasonable to ascribe the spectral distortions seen by Simpson, Hime, and others to a 17keV neutrino. Several new ideas on how to search for massive neutrinos in nuclear beta decay are discussed
International Nuclear Information System (INIS)
Zushi, H.; Hasegawa, M.; Hanada, K.; Idei, H.; Nakamura, K.; Fujisawa, A.; Nagashima, Y.; Matsuoka, K.; Tashima, S.; Ishiguro, M.; Banerjee, S.; Sharma, S.K.; Liu, H.; Nishino, N.; Isobe, M.; Toi, K.; Okamura, S.; Maekawa, T.; Fukuyama, A.; Ejiri, A.; Yamaguchi, T.; Hiratsuka, J.; Takase, Y.; Kikuchi, Mitsuru; Ueda, Y.; Mitarai, O.
2012-11-01
Non-inductive current start-up via relativistic electron cyclotron resonance interaction is investigated for the high ratio (∼10%) of vertical B v to toroidal B t fields and the concave field lines in the QUEST spherical tokamak. In the start-up scenario with an internal poloidal field null (IPN), the fast current start-up rate of 0.3-0.5 MA/sec and correlation with mildly relativistic electrons accelerated due to multiple ECR interaction are observed. In steady state high β p equilibrium characterized by the inboard null (R s ∼ 0.7×R 0 ) and εβ p of 1.5 is achieved, where ε, β p are the inverse aspect ratio and poloidal beta, respectively. Relaxation oscillations in this equilibrium and confinement of the energetic electrons are discussed. (author)
Gómez Trigueros, Isabel María
2015-01-01
En esta unidad aprenderéis a crear vuestros propios polígonos con Google Earth para delimitar un área geográfica. Podréis modificar el tamaño de los polígonos, el color del área y su perímetro, incluso elaborar polígonos en 3D para superponer distintas variables sobre un paisaje concreto.
DEFF Research Database (Denmark)
Christoffersen, Peter; Jacobs, Kris; Vainberg, Gregory
Few issues are more important for finance practice than the computation of market betas. Existing approaches compute market betas using historical data. While these approaches differ in terms of statistical sophistication and the modeling of the time-variation in the betas, they are all backward......-looking. This paper introduces a radically different approach to estimating market betas. Using the tools in Bakshi and Madan (2000) and Bakshi, Kapadia and Madan (2003) we employ the information embedded in the prices of individual stock options and index options to compute our forward-looking market beta...
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
Vacuum Nuller Testbed Performance, Characterization and Null Control
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.
A visualization of null geodesics for the bonnor massive dipole
Directory of Open Access Journals (Sweden)
G. Andree Oliva Mercado
2015-08-01
Full Text Available In this work we simulate null geodesics for the Bonnor massive dipole metric by implementing a symbolic-numerical algorithm in Sage and Python. This program is also capable of visualizing in 3D, in principle, the geodesics for any given metric. Geodesics are launched from a common point, collectively forming a cone of light beams, simulating a solid-angle section of a point source in front of a massive object with a magnetic field. Parallel light beams also were considered, and their bending due to the curvature of the space-time was simulated.
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)
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
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
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.)
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
Directory of Open Access Journals (Sweden)
Gabriel Gatti
2018-03-01
Full Text Available Trabajamos en las tensiones entre dos continentes en permanente disputa: “sangre” y “política”, “realidad” y “dispositivo”, “naturaleza” y “cultura”. Son viejos asuntos, y viejas tensiones, pero que no dejan de actualizarse y que ahora se manifiestan por doquier en cuestiones como la biometría, los mapas genéticos, la identificación de desaparecidos, las políticas de la identidad indígena o de género o de menores o de drogas, la gestación subrogada o la gestión de la marginalidad. Los diez textos recogidos en este número especial discuten desde una mirada interdisciplinaria sobre la presencia de la sangre —en sus distintas declinaciones— en la definición contemporánea de lo que entendemos por identidad, derechos humanos o ciudadanía.
The new null testing method for the special optical window
Huang, Changchun
2009-07-01
The high speed, high precision and wide range specifications are requirement for the modern aircraft, which the traditional hemispherical dome can't achieve now, and the novel conformal window instead can enhance the aerodynamic performance of the aircraft obviously. To reduce the aerodynamic drag and radar cross-section, the window geometry is generally aspheric in shape. As a result, the involved fabrication and testing processes are much more challenging than that of conventional optics and must be mastered before these windows and systems can be implemented at an acceptable cost and risk. Metrology is one of the critical areas required to advance the conformal window technology. But as the surface of these conformal windows is not the traditional sphere lens, the measurement method for it is infeasible with the conventional optics measurement processes. This paper we express the development of testing technology for the special conformal windows in brief, and emphatically introduces one available novel testing method- a new null testing, and here based on the theory of compensation methods, The principle of Offner's refractive null lens has been extended to test the transmission wavefront through conformal window optics and provide feedback during surface fabrication. a compensator system for the was designed for the conformal window is given which parameters are 100mm for its aperture and two parabolic surface as conformal window, the final residual wavefront error(RMS) of which is less than 1/20λ(λ=632.8nm).
Pituitary null cell adenoma in a domestic llama (Lama glama).
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.
Randomizing growing networks with a time-respecting null model
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.
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
Extrasolar Planetary Imaging Coronagraph (EPIC): visible nulling cornagraph testbed results
Lyon, Richard G.; Clampin, Mark; Melnick, Gary; Tolls, Volker; Woodruff, Robert; Vasudevan, Gopal
2008-07-01
The Extrasolar Planetary Imaging Coronagraph (EPIC) is a NASA Astrophysics Strategic Mission Concept under study for the upcoming Exoplanet Probe. EPIC's mission would be to image and characterize extrasolar giant planets, and potential super-Earths, 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 and potentially some transits, determine orbital inclinations and masses, characterize the atmospheres of gas giants around A and F stars, observed the inner spatial structure and colors of inner Spitzer selected debris disks. EPIC would be launched into a heliocentric Earth trailing drift-away orbit, with a 3-year mission lifetime (5 year goal) and will revisit planets at least three times. 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.
Extrasolar Planetary Imaging Coronagraph: Visible Nulling Coronagraph Testbed Results
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,
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).
Plate with a hole obeys the averaged null energy condition
International Nuclear Information System (INIS)
Graham, Noah; Olum, Ken D.
2005-01-01
The negative energy density of Casimir systems appears to violate general relativity energy conditions. However, one cannot test the averaged null energy condition (ANEC) using standard calculations for perfectly reflecting plates, because the null geodesic would have to pass through the plates, where the calculation breaks down. To avoid this problem, we compute the contribution to ANEC for a geodesic that passes through a hole in a single plate. We consider both Dirichlet and Neumann boundary conditions in two and three space dimensions. We use a Babinet's principle argument to reduce the problem to a complementary finite disk correction to the perfect mirror result, which we then compute using scattering theory in elliptical and spheroidal coordinates. In the Dirichlet case, we find that the positive correction due to the hole overwhelms the negative contribution of the infinite plate. In the Neumann case, where the infinite plate gives a positive contribution, the hole contribution is smaller in magnitude, so again ANEC is obeyed. These results can be extended to the case of two plates in the limits of large and small hole radii. This system thus provides another example of a situation where ANEC turns out to be obeyed when one might expect it to be violated
Política, marketing e neoliberalismo
Directory of Open Access Journals (Sweden)
Pedro Roberto Ferreira
2004-07-01
Full Text Available O texto contém uma análise da relação política e sua possível consciência no seu momento específico compreendido pelo processo eleitoral (Londrina - eleições 92. Como este processo eleitoral em nossos dias, nutre-se de algumas técnicas conhecidas como Marketing Político-Eleitoral, e de como estas, contribuem para uma dinâmica de esvaziamento da vida política propriamente dita. Procura ainda, conectar esse esvaziamento político e suas consequências, com o avanço da concepção neoliberal cujo ápice parece fazer coincidir a política como mais uma manifestação de Mercado.
DEFF Research Database (Denmark)
Frazzini, Andrea; Heje Pedersen, Lasse
We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model’s five central predictions: (1) Since constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically for U...... of the BAB factor is low; (4) Increased funding liquidity risk compresses betas toward one; (5) More constrained investors hold riskier assets........S. equities, 20 international equity markets, Treasury bonds, corporate bonds, and futures; (2) A betting-against-beta (BAB) factor, which is long leveraged low beta assets and short high-beta assets, produces significant positive risk-adjusted returns; (3) When funding constraints tighten, the return...
DEFF Research Database (Denmark)
Bollerslev, Tim; Li, Sophia Zhengzi; Todorov, Viktor
-section. An investment strategy that goes long stocks with high jump betas and short stocks with low jump betas produces significant average excess returns. These higher risk premiums for the discontinuous and overnight market betas remain significant after controlling for a long list of other firm characteristics......Motivated by the implications from a stylized equilibrium pricing framework, we investigate empirically how individual equity prices respond to continuous, or \\smooth," and jumpy, or \\rough," market price moves, and how these different market price risks, or betas, are priced in the cross......-section of expected returns. Based on a novel highfrequency dataset of almost one-thousand individual stocks over two decades, we find that the two rough betas associated with intraday discontinuous and overnight returns entail significant risk premiums, while the intraday continuous beta is not priced in the cross...
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.
International Nuclear Information System (INIS)
Helton, F.J.; Miller, R.L.
1982-01-01
ETF (Engineering Test Facility) one-dimensional transport simulations indicate that a volume-average beta of 4% is required for ignition. It is therefore important that theoretical beta limits, determined by requiring equilibria to be stable to all ideal modes, exceed 4%. This paper documents an ideal MHD analysis wherein it is shown that, with appropriate plasma cross-sectional shape and current profile optimization, operation near 5% is possible. The critical beta value, however, depends on the functional form used for ff', which suggests that higher critical betas could be achieved by directly optimizing the safety factor profile. (author)
Beta-energy averaging and beta spectra
International Nuclear Information System (INIS)
Stamatelatos, M.G.; England, T.R.
1976-07-01
A simple yet highly accurate method for approximately calculating spectrum-averaged beta energies and beta spectra for radioactive nuclei is presented. This method should prove useful for users who wish to obtain accurate answers without complicated calculations of Fermi functions, complex gamma functions, and time-consuming numerical integrations as required by the more exact theoretical expressions. Therefore, this method should be a good time-saving alternative for investigators who need to make calculations involving large numbers of nuclei (e.g., fission products) as well as for occasional users interested in restricted number of nuclides. The average beta-energy values calculated by this method differ from those calculated by ''exact'' methods by no more than 1 percent for nuclides with atomic numbers in the 20 to 100 range and which emit betas of energies up to approximately 8 MeV. These include all fission products and the actinides. The beta-energy spectra calculated by the present method are also of the same quality
Directory of Open Access Journals (Sweden)
Antoinette C. van der Kuyl
2011-06-01
Full Text Available Information on endogenous retroviruses fixed in the horse (Equus caballus genome is scarce. The recent availability of a draft sequence of the horse genome enables the detection of such integrated viruses by similarity search. Using translated nucleotide fragments from gamma-, beta-, and delta-retroviral genera for initial searches, a full-length beta-retrovirus genome was retrieved from a horse chromosome 5 contig. The provirus, tentatively named EqERV-beta1 (for the first equine endogenous beta-retrovirus, was 10434 nucleotide (nt in length with the usual retroviral genome structure of 5’LTR-gag-pro-pol-env-3’LTR. The LTRs were 1361 nt long, and differed approximately 1% from each other, suggestive of a relatively recent integration. Coding sequences for gag, pro and pol were present in three different reading-frames, as common for beta-retroviruses, and the reading frames were completely open, except that the env gene was interrupted by a single stopcodon. No reading frame was apparent downstream of the env gene, suggesting that EqERV-beta1 does not encode a superantigen like mouse mammary tumor virus (MMTV. A second proviral genome of EqERV-beta1, with no stopcodon in env, is additionally integrated on chromosome 5 downstream of the first virus. Single EqERV-beta1 LTRs were abundantly present on all chromosomes except chromosome 24. Phylogenetically, EqERV-beta1 most closely resembles an unclassified retroviral sequence from cattle (Bos taurus, and the murine beta-retrovirus MMTV.
Mice null for the deubiquitinase USP18 spontaneously develop leiomyosarcomas
International Nuclear Information System (INIS)
Chinyengetere, Fadzai; Sekula, David J.; Lu, Yun; Giustini, Andrew J.; Sanglikar, Aarti; Kawakami, Masanori; Ma, Tian; Burkett, Sandra S.; Eisenberg, Burton L.; Wells, Wendy A.; Hoopes, Paul J.; Demicco, Elizabeth G.; Lazar, Alexander J; Torres, Keila E.; Memoli, Vincent; Freemantle, Sarah J.; Dmitrovsky, Ethan
2015-01-01
USP18 (ubiquitin-specific protease 18) removes ubiquitin-like modifier interferon stimulated gene 15 (ISG15) from conjugated proteins. USP18 null mice in a FVB/N background develop tumors as early as 2 months of age. These tumors are leiomyosarcomas and thus represent a new murine model for this disease. Heterozygous USP18 +/− FVB/N mice were bred to generate wild-type, heterozygous and homozygous cohorts. Tumors were characterized immunohistochemically and two cell lines were derived from independent tumors. Cell lines were karyotyped and their responses to restoration of USP18 activity assessed. Drug testing and tumorigenic assays were also performed. USP18 immunohistochemical staining in a large series of human leiomyosacomas was examined. USP18 −/− FVB/N mice spontaneously develop tumors predominantly on the back of the neck with most tumors evident between 6–12 months (80 % penetrance). Immunohistochemical characterization of the tumors confirmed they were leiomyosarcomas, which originate from smooth muscle. Restoration of USP18 activity in sarcoma-derived cell lines did not reduce anchorage dependent or independent growth or xenograft tumor formation demonstrating that these cells no longer require USP18 suppression for tumorigenesis. Karyotyping revealed that both tumor-derived cell lines were aneuploid with extra copies of chromosomes 3 and 15. Chromosome 15 contains the Myc locus and MYC is also amplified in human leiomyosarcomas. MYC protein levels were elevated in both murine leiomyosarcoma cell lines. Stabilized P53 protein was detected in a subset of these murine tumors, another feature of human leiomyosarcomas. Immunohistochemical analyses of USP18 in human leiomyosarcomas revealed a range of staining intensities with the highest USP18 expression in normal vascular smooth muscle. USP18 tissue array analysis of primary leiomyosarcomas from 89 patients with a clinical database revealed cases with reduced USP18 levels had a significantly
Directory of Open Access Journals (Sweden)
MANUEL JUSTEL
1992-01-01
Full Text Available En este artículo se analiza la evolución de algunos aspectos de la cultura política y democrática durante los años ochenta: información y competencia política, participación política, actitudes hacia los partidos y orientaciones políticas. Los datos proceden de sendas encuestas realizadas en 1980 y 1989. Mediante análisis de cohortes de edad, controlando sexo y nivel de estudios, se comprueba el grado diferencial de expansión de actitudes democráticas en los grupos de edad, controlando sexo y nivel de estudios, se comprueba el grado diferencial de expansión de actitudes democráticas en los grupos de edad, el efecto homogeneizador que conlleva y el influjo estratégico de la educación. En el marco teórico de la socialización política en edad adulta y de las relaciones entre sistema social y sistema político, se interpretan los cambios de actitudes distinguiendo efectos de ciclo vital, de cohorte y de periodo. Al mismo tiempo, se discuten algunas consecuencias políticas del envejecimiento poblacional y se constata de un grado notable de plasticidad actitudinal y de adhesión creciente a la democracia de las cohortes de edad avanzada.
Radiation Hardened NULL Convention Logic Asynchronous Circuit Design
Directory of Open Access Journals (Sweden)
Liang Zhou
2015-10-01
Full Text Available This paper proposes a radiation hardened NULL Convention Logic (NCL architecture that can recover from a single event latchup (SEL or single event upset (SEU fault without deadlock or any data loss. The proposed architecture is analytically proved to be SEL resistant, and by extension, proved to be SEU resistant. The SEL/SEU resistant version of a 3-stage full-word pipelined NCL 4 × 4 unsigned multiplier was implemented using the IBM cmrf8sf 130 nm 1.2 V process at the transistor level and simulated exhaustively with SEL fault injection to validate the proposed architectures. Compared with the original version, the SEL/SEU resilient version has 1.31× speed overhead, 2.74× area overhead, and 2.79× energy per operation overhead.
The simple map for a single-null divertor tokamak
International Nuclear Information System (INIS)
Punjabi, A.; Verma, A.; Boozer, A.
1996-01-01
We present the simple map for a single-null divertor tokamak. The simple map is an area-preserving map based on the idea that magnetic field lines are a single-degree-of-freedom time-dependent Hamiltonian system, and that the basic features of such systems near the X-point are generic. We obtain the properties of this map and the resulting footprints of field lines on the divertor plate. These include the width of the stochastic layer, the edge safety factor, the area of the footprint and the amount of magnetic flux diverted. We give the safety factor profile, the average and median values of strike angles, lengths and the Liapunov exponents. We describe how the effects of magnetic perturbations can be included in the simple map. We show how the map can be applied to the problem of the determination of heat flux on the divertor plate in tokamaks. (Author)
Status of the Visible Nulling Coronagraph Technology Demonstration Program
Clampin, M.; Lyon, R.
2012-01-01
We report on the development, sensing and control of the Vacuum Nuller Testbed to realize a Visible Nulling Coronagraphy (VNC) for exoplanet detection and characterization. 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 has an established effort to develop VNC technologies, and an incremental sequence of testbeds to advance this approach and its critical technologies. We will highlight results demonstrating the achievement of our TDEM contrast milestones, and highlight the performance of our wavefront sensing and control concept.
Horizons in Matter:. Black Hole Hair Versus Null Big Bang
Bronnikov, K. A.; Zaslavskii, Oleg B.
It is shown that only particular kinds of matter (in terms of the "radial" pressure-to-density ratio w) can coexist with Killing horizons in black hole or cosmological space-times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter (w = -1, i.e. the cosmological constant or its generalization with the same value of w) and matter with certain values of w between 0 and -1, in particular a gas of disordered cosmic strings (w = -1/3). If the cosmological evolution starts from a horizon (the so-called null big bang scenarios), this horizon can coexist with vacuum matter and certain kinds of phantom matter with w ≤ -3. It is concluded that normal matter in such scenarios is entirely created from vacuum.
International Nuclear Information System (INIS)
Dory, R.A.; Berger, D.P.; Charlton, L.A.; Hogan, J.T.; Munro, J.K.; Nelson, D.B.; Peng, Y.K.M.; Sigmar, D.J.; Strickler, D.J.
1978-01-01
MHD equilibrium, stability, and transport calculations are made to study the accessibility and behavior of ''high beta'' tokamak plasmas in the range β approximately 5 to 15 percent. For next generation devices, beta values of at least 8 percent appear to be accessible and stable if there is a conducting surface nearby
G.T. Post (Thierry); P. van Vliet (Pim); S.D. Lansdorp (Simon)
2009-01-01
textabstractDownside risk, when properly defined and estimated, helps to explain the cross-section of US stock returns. Sorting stocks by a proper estimate of downside market beta leads to a substantially larger cross-sectional spread in average returns than sorting on regular market beta. This
DEFF Research Database (Denmark)
Frazzini, Andrea; Heje Pedersen, Lasse
2014-01-01
We present a model with leverage and margin constraints that vary across investors and time. We find evidence consistent with each of the model's five central predictions: (1) Because constrained investors bid up high-beta assets, high beta is associated with low alpha, as we find empirically...
Cadmium modulates adipocyte functions in metallothionein-null mice
Energy Technology Data Exchange (ETDEWEB)
Kawakami, Takashige; Nishiyama, Kaori; Kadota, Yoshito; Sato, Masao; Inoue, Masahisa; Suzuki, Shinya, E-mail: suzukis@ph.bunri-u.ac.jp
2013-11-01
Our previous study has demonstrated that exposure to cadmium (Cd), a toxic heavy metal, causes a reduction of adipocyte size and the modulation of adipokine expression. To further investigate the significance of the Cd action, we studied the effect of Cd on the white adipose tissue (WAT) of metallothionein null (MT{sup −/−}) mice, which cannot form atoxic Cd–MT complexes and are used for evaluating Cd as free ions, and wild type (MT{sup +/+}) mice. Cd administration more significantly reduced the adipocyte size of MT{sup −/−} mice than that of MT{sup +/+} mice. Cd exposure also induced macrophage recruitment to WAT with an increase in the expression level of Ccl2 (MCP-1) in the MT{sup −/−} mice. The in vitro exposure of Cd to adipocytes induce triglyceride release into culture medium, decrease in the expression levels of genes involved in fatty acid synthesis and lipid hydrolysis at 24 h, and at 48 h increase in phosphorylation of the lipid-droplet-associated protein perilipin, which facilitates the degradation of stored lipids in adipocytes. Therefore, the reduction in adipocyte size by Cd may arise from an imbalance between lipid synthesis and lipolysis. In addition, the expression levels of leptin, adiponectin and resistin decreased in adipocytes. Taken together, exposure to Cd may induce unusually small adipocytes and modulate the expression of adipokines differently from the case of physiologically small adipocytes, and may accelerate the risk of developing insulin resistance and type 2 diabetes. - Highlights: • Cd causes a marked reduction in adipocyte size in MT-null mice. • Cd enhances macrophage migration into adipose tissue and disrupt adipokine secretion. • MT gene alleviates Cd-induced adipocyte dysfunctions. • Cd enhances the degradation of stored lipids in adipocytes, mediated by perilipin. • Cd induces unusually small adipocytes and the abnormal expression of adipokines.
Dinucleotide controlled null models for comparative RNA gene prediction
Directory of Open Access Journals (Sweden)
Gesell Tanja
2008-05-01
Full Text Available Abstract Background Comparative prediction of RNA structures can be used to identify functional noncoding RNAs in genomic screens. It was shown recently by Babak et al. [BMC Bioinformatics. 8:33] that RNA gene prediction programs can be biased by the genomic dinucleotide content, in particular those programs using a thermodynamic folding model including stacking energies. As a consequence, there is need for dinucleotide-preserving control strategies to assess the significance of such predictions. While there have been randomization algorithms for single sequences for many years, the problem has remained challenging for multiple alignments and there is currently no algorithm available. Results We present a program called SISSIz that simulates multiple alignments of a given average dinucleotide content. Meeting additional requirements of an accurate null model, the randomized alignments are on average of the same sequence diversity and preserve local conservation and gap patterns. We make use of a phylogenetic substitution model that includes overlapping dependencies and site-specific rates. Using fast heuristics and a distance based approach, a tree is estimated under this model which is used to guide the simulations. The new algorithm is tested on vertebrate genomic alignments and the effect on RNA structure predictions is studied. In addition, we directly combined the new null model with the RNAalifold consensus folding algorithm giving a new variant of a thermodynamic structure based RNA gene finding program that is not biased by the dinucleotide content. Conclusion SISSIz implements an efficient algorithm to randomize multiple alignments preserving dinucleotide content. It can be used to get more accurate estimates of false positive rates of existing programs, to produce negative controls for the training of machine learning based programs, or as standalone RNA gene finding program. Other applications in comparative genomics that require
Dinucleotide controlled null models for comparative RNA gene prediction.
Gesell, Tanja; Washietl, Stefan
2008-05-27
Comparative prediction of RNA structures can be used to identify functional noncoding RNAs in genomic screens. It was shown recently by Babak et al. [BMC Bioinformatics. 8:33] that RNA gene prediction programs can be biased by the genomic dinucleotide content, in particular those programs using a thermodynamic folding model including stacking energies. As a consequence, there is need for dinucleotide-preserving control strategies to assess the significance of such predictions. While there have been randomization algorithms for single sequences for many years, the problem has remained challenging for multiple alignments and there is currently no algorithm available. We present a program called SISSIz that simulates multiple alignments of a given average dinucleotide content. Meeting additional requirements of an accurate null model, the randomized alignments are on average of the same sequence diversity and preserve local conservation and gap patterns. We make use of a phylogenetic substitution model that includes overlapping dependencies and site-specific rates. Using fast heuristics and a distance based approach, a tree is estimated under this model which is used to guide the simulations. The new algorithm is tested on vertebrate genomic alignments and the effect on RNA structure predictions is studied. In addition, we directly combined the new null model with the RNAalifold consensus folding algorithm giving a new variant of a thermodynamic structure based RNA gene finding program that is not biased by the dinucleotide content. SISSIz implements an efficient algorithm to randomize multiple alignments preserving dinucleotide content. It can be used to get more accurate estimates of false positive rates of existing programs, to produce negative controls for the training of machine learning based programs, or as standalone RNA gene finding program. Other applications in comparative genomics that require randomization of multiple alignments can be considered. SISSIz
Does horizon entropy satisfy a quantum null energy conjecture?
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.
3D Solar Null Point Reconnection MHD Simulations
Baumann, G.; Galsgaard, K.; Nordlund, Å.
2013-06-01
Numerical MHD simulations of 3D reconnection events in the solar corona have improved enormously over the last few years, not only in resolution, but also in their complexity, enabling more and more realistic modeling. Various ways to obtain the initial magnetic field, different forms of solar atmospheric models as well as diverse driving speeds and patterns have been employed. This study considers differences between simulations with stratified and non-stratified solar atmospheres, addresses the influence of the driving speed on the plasma flow and energetics, and provides quantitative formulas for mapping electric fields and dissipation levels obtained in numerical simulations to the corresponding solar quantities. The simulations start out from a potential magnetic field containing a null-point, obtained from a Solar and Heliospheric Observatory (SOHO) Michelson Doppler Imager (MDI) magnetogram magnetogram extrapolation approximately 8 hours before a C-class flare was observed. The magnetic field is stressed with a boundary motion pattern similar to - although simpler than - horizontal motions observed by SOHO during the period preceding the flare. The general behavior is nearly independent of the driving speed, and is also very similar in stratified and non-stratified models, provided only that the boundary motions are slow enough. The boundary motions cause a build-up of current sheets, mainly in the fan-plane of the magnetic null-point, but do not result in a flare-like energy release. The additional free energy required for the flare could have been partly present in non-potential form at the initial state, with subsequent additions from magnetic flux emergence or from components of the boundary motion that were not represented by the idealized driving pattern.
Molecular bass for a malic enzyme null mutation
International Nuclear Information System (INIS)
Brown, M.L.; Wise, L.S.; Rubin, C.S.
1987-01-01
Many tissues from normal (wt) mice have cytosolic malic enzyme (ME) activity and express two mRNAs (2 and 3.1 kb) that code for a single ME polypeptide. Mod-1 null (M-n) mice lack cytosolic ME activity, but express 2.5 and 3.6 kb mRNAs that hybridize with wt ME cDNAs. To investigate the basis for the ME deficiency cDNAs corresponding to M-n ME RNA were cloned. A λgt11 library was prepared using M-n liver mRNA as a template. Wt ME cDNA probes hybridized with several recombinant phages and a 2kb insert with an atypical (non-wt) restriction pattern was subcloned in pGEM 1 and sequenced. The M-n ME cDNA contains an internal directly repeated sequence that corresponds to nts 1109-1617 in the coding region of wt ME cDNA. A restriction fragment from M-n ME cDNA that includes the first 204 bp of repeated sequence and 306 bp of contiguous 5' sequence was subcloned into pGEM 1 and used as a template for synthesizing 32 P-labeled anti-sense RNA. After hybridization with M-n liver RNA the 510 nt transcript was resistant to RNA digestion; after hybridization with wt RNA only fragments corresponding to the normally non-contiguous 204 bp and 306 bp segments of the insert were protected. Thus the partial duplication of coding sequence in M-n ME mRNA is confirmed. Analyses of intron-exon organization in the relevant regions of the wt and M-n ME genes will provide further insights into the mechanism underlying the ME null mutation
Surprising structures hiding in Penrose’s future null infinity
Newman, Ezra T.
2017-07-01
Since the late1950s, almost all discussions of asymptotically flat (Einstein-Maxwell) space-times have taken place in the context of Penrose’s null infinity, I+. In addition, almost all calculations have used the Bondi coordinate and tetrad systems. Beginning with a known asymptotically flat solution to the Einstein-Maxwell equations, we show first, that there are other natural coordinate systems, near I+, (analogous to light-cones in flat-space) that are based on (asymptotically) shear-free null geodesic congruences (analogous to the flat-space case). Using these new coordinates and their associated tetrad, we define the complex dipole moment, (the mass dipole plus i times angular momentum), from the l = 1 harmonic coefficient of a component of the asymptotic Weyl tensor. Second, from this definition, from the Bianchi identities and from the Bondi-Sachs mass and linear momentum, we show that there exists a large number of results—identifications and dynamics—identical to those of classical mechanics and electrodynamics. They include, among many others, {P}=M{v}+..., {L}= {r} × {P} , spin, Newton’s second law with the rocket force term (\\dotM v) and radiation reaction, angular momentum conservation and others. All these relations take place in the rather mysterious H-space rather than in space-time. This leads to the enigma: ‘why do these well known relations of classical mechanics take place in H-space?’ and ‘What is the physical meaning of H-space?’
Is PMI the Hypothesis or the Null Hypothesis?
Tarone, Aaron M; Sanford, Michelle R
2017-09-01
Over the past several decades, there have been several strident exchanges regarding whether forensic entomologists estimate the postmortem interval (PMI), minimum PMI, or something else. During that time, there has been a proliferation of terminology reflecting this concern regarding "what we do." This has been a frustrating conversation for some in the community because much of this debate appears to be centered on what assumptions are acknowledged directly and which are embedded within a list of assumptions (or ignored altogether) in the literature and in case reports. An additional component of the conversation centers on a concern that moving away from the use of certain terminology like PMI acknowledges limitations and problems that would make the application of entomology appear less useful in court-a problem for lawyers, but one that should not be problematic for scientists in the forensic entomology community, as uncertainty is part of science that should and can be presented effectively in the courtroom (e.g., population genetic concepts in forensics). Unfortunately, a consequence of the way this conversation is conducted is that even as all involved in the debate acknowledge the concerns of their colleagues, parties continue to talk past one another advocating their preferred terminology. Progress will not be made until the community recognizes that all of the terms under consideration take the form of null hypothesis statements and that thinking about "what we do" as a null hypothesis has useful legal and scientific ramifications that transcend arguments over the usage of preferred terminology. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Observation of a 3D Magnetic Null Point
Energy Technology Data Exchange (ETDEWEB)
Romano, P.; Falco, M. [INAF—Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania (Italy); Guglielmino, S. L.; Murabito, M., E-mail: prom@oact.inaf.it [Dipartimento di Fisica e Astronomia—Sezione Astrofisica, Università di Catania, Via S. Sofia 78, I-95123 Catania (Italy)
2017-03-10
We describe high-resolution observations of a GOES B-class flare characterized by a circular ribbon at the chromospheric level, corresponding to the network at the photospheric level. We interpret the flare as a consequence of a magnetic reconnection event that occurred at a three-dimensional (3D) coronal null point located above the supergranular cell. The potential field extrapolation of the photospheric magnetic field indicates that the circular chromospheric ribbon is cospatial with the fan footpoints, while the ribbons of the inner and outer spines look like compact kernels. We found new interesting observational aspects that need to be explained by models: (1) a loop corresponding to the outer spine became brighter a few minutes before the onset of the flare; (2) the circular ribbon was formed by several adjacent compact kernels characterized by a size of 1″–2″; (3) the kernels with a stronger intensity emission were located at the outer footpoint of the darker filaments, departing radially from the center of the supergranular cell; (4) these kernels started to brighten sequentially in clockwise direction; and (5) the site of the 3D null point and the shape of the outer spine were detected by RHESSI in the low-energy channel between 6.0 and 12.0 keV. Taking into account all these features and the length scales of the magnetic systems involved in the event, we argue that the low intensity of the flare may be ascribed to the low amount of magnetic flux and to its symmetric configuration.
Genetics Home Reference: beta thalassemia
... Facebook Twitter Home Health Conditions Beta thalassemia Beta thalassemia Printable PDF Open All Close All Enable Javascript to view the expand/collapse boxes. Description Beta thalassemia is a blood disorder that reduces the production ...
DEFF Research Database (Denmark)
Grose, Richard; Hutter, Caroline; Bloch, Wilhelm
2002-01-01
of beta 1 integrins in keratinocytes caused a severe defect in wound healing. beta 1-null keratinocytes showed impaired migration and were more densely packed in the hyperproliferative epithelium. Surprisingly, their proliferation rate was not reduced in early wounds and even increased in late wounds....... The failure in re-epithelialisation resulted in a prolonged inflammatory response, leading to dramatic alterations in the expression of important wound-regulated genes. Ultimately, beta 1-deficient epidermis did cover the wound bed, but the epithelial architecture was abnormal. These findings demonstrate...
Rapid synthesis of beta zeolites
Fan, Wei; Chang, Chun -Chih; Dornath, Paul; Wang, Zhuopeng
2015-08-18
The invention provides methods for rapidly synthesizing heteroatom containing zeolites including Sn-Beta, Si-Beta, Ti-Beta, Zr-Beta and Fe-Beta. The methods for synthesizing heteroatom zeolites include using well-crystalline zeolite crystals as seeds and using a fluoride-free, caustic medium in a seeded dry-gel conversion method. The Beta zeolite catalysts made by the methods of the invention catalyze both isomerization and dehydration reactions.
Fuels and Petroleum, Oil & Lubricants (POL) Laboratories
Federal Laboratory Consortium — The Fuels and Lubricants Technology Team operates and maintains the Fuels and POL Labs at TARDEC. Lab experts adhere to standardized American Society for Testing and...
Characterization of an extrapolation chamber in a 90Sr/90Y beta radiation field
International Nuclear Information System (INIS)
Oramas Polo, I.; Tamayo Garcia, J. A.
2015-01-01
The extrapolation chamber is a parallel plate chamber and variable volume based on the Bragg-Gray theory. It determines in absolute mode, with high accuracy the dose absorbed by the extrapolation of the ionization current measured for a null distance between the electrodes. This camera is used for dosimetry of external beta rays for radiation protection. This paper presents the characterization of an extrapolation chamber in a 90 Sr/ 90 Y beta radiation field. The absorbed dose rate to tissue at a depth of 0.07 mm was calculated and is (0.13206±0.0028) μGy. The extrapolation chamber null depth was determined and its value is 60 μm. The influence of temperature, pressure and humidity on the value of the corrected current was also evaluated. Temperature is the parameter that has more influence on this value and the influence of pressure and the humidity is not very significant. Extrapolation curves were obtained. (Author)
Properties of an extrapolation chamber for beta radiation dosimetry
International Nuclear Information System (INIS)
Caldas, L.V.E.
The properties of a commercial extrapolation chamber were studied, and the possibility is shown of its use in beta radiation dosimetry. The chamber calibration factors were determined for several sources ( 90 Sr, 90 Y- 204 Tl and 147 Pm) making known the dependence of its response on the energy of the incident radiation. Extrapolation curves allow to obtain independence on energy for each source. One of such curves, shown for the 90 Sr- 90 Y source at 50 cm from the detector, is obtained through the variation of the chamber window thickness and the extrapolation to the null distance (determined graphically). Different curves shown also: 1) the dependence of the calibration factor on the average energy of beta radiation; 2) the variation of ionization current with the distance between the chamber and the sources; 3) the effect of the collecting electrode area on the value of calibration factors for the different sources. (I.C.R.) [pt
Beta particle measurement fundamentals
International Nuclear Information System (INIS)
Alvarez, J.L.
1986-01-01
The necessary concepts for understanding beta particle behavior are stopping power, range, and scattering. Dose as a consequence of beta particle interaction with tissue can be derived and explained by these concepts. Any calculations of dose, however, assume or require detailed knowledge of the beta spectrum at the tissue depth of calculation. A rudimentary knowledge of the incident spectrum can be of use in estimating dose, interpretating dose measuring devices and designing protection. The stopping power and range based on the csda will give a conservative estimate in cases of protection design, as scattering will reduce the range. Estimates of dose may be low because scattering effects were neglected
Dependence of {beta} {center_dot} {tau} on plasma shape in DIII-D
Energy Technology Data Exchange (ETDEWEB)
Lazarus, E.A. [Oak Ridge National Lab., TN (United States)
1993-12-31
In this paper we discuss the observed variation in plasma performance with plasma shape, in particular, we shall compare single and double null diverted plasmas. The product {beta} {center_dot} {tau} has been used as a figure-of-merit for comparing different toroidal magnetic configurations. Here we shall use it as the figure-of-merit for comparing differing configurations within the DIII-D tokamak. (author) 5 refs., 5 figs.
Qualification of a Null Lens Using Image-Based Phase Retrieval
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.
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.)
de Fiebre, Nancyellen C; de Fiebre, Christopher M
2005-01-03
The alpha7 subtype of nicotinic acetylcholine receptor (nAChR) has been implicated as a potential site of action for two neurotoxins, ethanol and the Alzheimer's disease related peptide, beta-amyloid. Here, we utilized primary neuronal cultures of cerebral cortex from alpha7 nAChR null mutant mice to examine the role of this receptor in modulating the neurotoxic properties of subchronic, "binge" ethanol and beta-amyloid. Knockout of the alpha7 nAChR gene selectively enhanced ethanol-induced neurotoxicity in a gene dosage-related fashion. Susceptibility of cultures to beta-amyloid induced toxicity, however, was unaffected by alpha7 nAChR gene null mutation. Further, beta-amyloid did not inhibit the binding of the highly alpha7-selective radioligand, [(125)I]alpha-bungarotoxin. On the other hand, in studies in Xenopus oocytes ethanol efficaciously inhibited alpha7 nAChR function. These data suggest that alpha7 nAChRs modulate the neurotoxic effects of binge ethanol, but not the neurotoxicity produced by beta-amyloid. It is hypothesized that inhibition of alpha7 nAChRs by ethanol provides partial protection against the neurotoxic properties of subchronic ethanol.
Neutrinoless double beta decay
Indian Academy of Sciences (India)
2012-10-06
Oct 6, 2012 ... Anyhow, the 'multi-isotope' ansatz is needed to compensate for matrix element ... The neccessary half-life requirement to touch this ... site energy depositions (like double beta decay) and multiple site interactions (most of.
... disease (COPD). It is also used to improve memory and muscle strength. Some people use beta-carotene ... to reduce the chance of death and night blindness during pregnancy, as well as diarrhea and fever ...
Double beta decay: experiments
International Nuclear Information System (INIS)
Fiorini, Ettore
2006-01-01
The results obtained so far and those of the running experiments on neutrinoless double beta decay are reviewed. The plans for second generation experiments, the techniques to be adopted and the expected sensitivities are compared and discussed
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.
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.
Nulling interferometry for the darwin mission: laboratory demonstration experiment
Ollivier, Marc; Léger, Alain; Sekulic, Predrag; Labèque, Alain; Michel, Guy
2017-11-01
The DARWIN mission is a project of the European Space Agency that should allow around 2012 the search for extrasolar planets and a spectral analysis of their potential atmosphere in order to evidence gases and particularly tracers of life. The principle of the instrument is based on the Bracewell nulling interferometer. It allows high angular resolution and high dynamic range. However, this concept, proposed more than 20 years ago, has never been experimentally demonstrated in the thermal infrared with high levels of extinction. We present here a laboratory monochromatic experiment dedicated to this goal. A theoretical and numerical approach of the question highlights a strong difficulty: the need for very clean and homogeneous wavefronts, in terms of intensity, phase and polarisation distribution. A classical interferometric approach appears to be insufficient to reach our goals. We have shown theoretically then numerically that this difficulty can be surpassed if we perform an optical filtering of the interfering beams. This technique allows us to decrease strongly the optical requirements and to view very high interferometric contrast measurements with commercial optical pieces. We present here a laboratory interferometer working at 10,6 microns, and implementing several techniques of optical filtering (pinholes and single-mode waveguides), its realisation, and its first promising results. We particularly present measurements that exhibit stable visibility levels better than 99,9% that is to say extinction levels better than 1000.
Constrained Null Space Component Analysis for Semiblind Source Separation Problem.
Hwang, Wen-Liang; Lu, Keng-Shih; Ho, Jinn
2018-02-01
The blind source separation (BSS) problem extracts unknown sources from observations of their unknown mixtures. A current trend in BSS is the semiblind approach, which incorporates prior information on sources or how the sources are mixed. The constrained independent component analysis (ICA) approach has been studied to impose constraints on the famous ICA framework. We introduced an alternative approach based on the null space component (NCA) framework and referred to the approach as the c-NCA approach. We also presented the c-NCA algorithm that uses signal-dependent semidefinite operators, which is a bilinear mapping, as signatures for operator design in the c-NCA approach. Theoretically, we showed that the source estimation of the c-NCA algorithm converges with a convergence rate dependent on the decay of the sequence, obtained by applying the estimated operators on corresponding sources. The c-NCA can be formulated as a deterministic constrained optimization method, and thus, it can take advantage of solvers developed in optimization society for solving the BSS problem. As examples, we demonstrated electroencephalogram interference rejection problems can be solved by the c-NCA with proximal splitting algorithms by incorporating a sparsity-enforcing separation model and considering the case when reference signals are available.
A null relationship between media multitasking and well-being.
Directory of Open Access Journals (Sweden)
Shui-I Shih
Full Text Available There is a rapidly increasing trend in media-media multitasking or MMM (using two or more media concurrently. In a recent conference, scholars from diverse disciplines expressed concerns that indulgence in MMM may compromise well-being and/or cognitive abilities. However, research on MMM's impacts is too sparse to inform the general public and policy makers whether MMM should be encouraged, managed, or minimized. The primary purpose of the present study was to develop an innovative computerized instrument--the Survey of the Previous Day (SPD--to quantify MMM as well as media-nonmedia and nonmedia-nonmedia multitasking and sole-tasking. The secondary purpose was to examine whether these indices could predict a sample of well-being related, psychosocial measures. In the SPD, participants first recalled (typed what they did during each hour of the previous day. In later parts of the SPD, participants analysed activities and their timing and duration for each hour of the previous day, while relevant recall was on display. Participants also completed the Media Use Questionnaire. The results showed non-significant relationship between tasking measures and well-being related measures. Given how little is known about the associations between MMM and well-being, the null results may offer some general reassurance to those who are apprehensive about negative impacts of MMM.
A Null Relationship between Media Multitasking and Well-Being
Shih, Shui-I
2013-01-01
There is a rapidly increasing trend in media-media multitasking or MMM (using two or more media concurrently). In a recent conference, scholars from diverse disciplines expressed concerns that indulgence in MMM may compromise well-being and/or cognitive abilities. However, research on MMM's impacts is too sparse to inform the general public and policy makers whether MMM should be encouraged, managed, or minimized. The primary purpose of the present study was to develop an innovative computerized instrument – the Survey of the Previous Day (SPD) – to quantify MMM as well as media-nonmedia and nonmedia-nonmedia multitasking and sole-tasking. The secondary purpose was to examine whether these indices could predict a sample of well-being related, psychosocial measures. In the SPD, participants first recalled (typed) what they did during each hour of the previous day. In later parts of the SPD, participants analysed activities and their timing and duration for each hour of the previous day, while relevant recall was on display. Participants also completed the Media Use Questionnaire. The results showed non-significant relationship between tasking measures and well-being related measures. Given how little is known about the associations between MMM and well-being, the null results may offer some general reassurance to those who are apprehensive about negative impacts of MMM. PMID:23691236
Conical twist fields and null polygonal Wilson loops
Castro-Alvaredo, Olalla A.; Doyon, Benjamin; Fioravanti, Davide
2018-06-01
Using an extension of the concept of twist field in QFT to space-time (external) symmetries, we study conical twist fields in two-dimensional integrable QFT. These create conical singularities of arbitrary excess angle. We show that, upon appropriate identification between the excess angle and the number of sheets, they have the same conformal dimension as branch-point twist fields commonly used to represent partition functions on Riemann surfaces, and that both fields have closely related form factors. However, we show that conical twist fields are truly different from branch-point twist fields. They generate different operator product expansions (short distance expansions) and form factor expansions (large distance expansions). In fact, we verify in free field theories, by re-summing form factors, that the conical twist fields operator product expansions are correctly reproduced. We propose that conical twist fields are the correct fields in order to understand null polygonal Wilson loops/gluon scattering amplitudes of planar maximally supersymmetric Yang-Mills theory.
Lovelock vacua with a recurrent null vector field
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.
{beta} - amyloid imaging probes
Energy Technology Data Exchange (ETDEWEB)
Jeong, Jae Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)
2007-04-15
Imaging distribution of {beta} - amyloid plaques in Alzheimer's disease is very important for early and accurate diagnosis. Early trial of the {beta} -amyloid plaques includes using radiolabeled peptides which can be only applied for peripheral {beta} - amyloid plaques due to limited penetration through the blood brain barrier (BBB). Congo red or Chrysamine G derivatives were labeled with Tc-99m for imaging {beta} - amyloid plaques of Alzheimer patient's brain without success due to problem with BBB penetration. Thioflavin T derivatives gave breakthrough for {beta} - amyloid imaging in vivo, and a benzothiazole derivative [C-11]6-OH-BTA-1 brought a great success. Many other benzothiazole, benzoxazole, benzofuran, imidazopyridine, and styrylbenzene derivatives have been labeled with F-18 and I-123 to improve the imaging quality. However, [C-11]6-OH-BTA-1 still remains as the best. However, short half-life of C-11 is a limitation of wide distribution of this agent. So, it is still required to develop an Tc-99m, F-18 or I-123 labeled agent for {beta} - amyloid imaging agent.
La carrera política y el capital político
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Manuel Alcántara-Sáez
2017-01-01
Full Text Available Se trata de una propuesta de naturaleza teórica para el estudio de las carreras políticas desde la perspectiva de la existencia de tres momentos diferentes (entrada, desempeño y salida, en conformidad con el uso del capital político que gestionan los políticos. Se abordan teóricamente distintos patrones de capital político así como su impacto sobre las trayectorias políticas seguidas. El peso del tiempo transcurrido y los ingresos recibidos por la actividad política son igualmente considerados. Político es aquella persona que es elegida en un proceso electoral y/o que es nominada en un puesto de confianza por alguien elegido, también lo es quien tiene un cargo orgánico en una institución como un partido político. A ello debe sumarse recibir una remuneración por esa actividad.
International Nuclear Information System (INIS)
Sidorenko, Julia; Jatsenko, Tatjana; Saumaa, Signe; Teras, Riho; Tark-Dame, Mariliis; Horak, Rita; Kivisaar, Maia
2011-01-01
The majority of bacteria possess a different set of specialized DNA polymerases than those identified in the most common model organism Escherichia coli. Here, we have studied the ability of specialized DNA polymerases to substitute Pol I in DNA replication in Pseudomonas putida. Our results revealed that P. putida Pol I-deficient cells have severe growth defects in LB medium, which is accompanied by filamentous cell morphology. However, growth of Pol I-deficient bacteria on solid rich medium can be restored by reduction of reactive oxygen species in cells. Also, mutants with improved growth emerge rapidly. Similarly to the initial Pol I-deficient P. putida, its adapted derivatives express a moderate mutator phenotype, which indicates that DNA replication carried out in the absence of Pol I is erroneous both in the original Pol I-deficient bacteria and the adapted derivatives. Analysis of the spectra of spontaneous Rif r mutations in P. putida strains lacking different DNA polymerases revealed that the presence of specialized DNA polymerases Pol II and Pol IV influences the frequency of certain base substitutions in Pol I-proficient and Pol I-deficient backgrounds in opposite ways. Involvement of another specialized DNA polymerase DnaE2 in DNA replication in Pol I-deficient bacteria is stimulated by UV irradiation of bacteria, implying that DnaE2-provided translesion synthesis partially substitutes the absence of Pol I in cells containing heavily damaged DNA.
Single Null Negative Triangularity Tokamak for Power Handling
Kikuchi, Mitsuru; Medvedev, S.; Takizuka, T.; Sauter, O.; Merle, A.; Coda, S.; Chen, D.; Li, J. X.
2017-10-01
Power and particle control in fusion reactor is challenge and we proposed the negative triangularity tokamak (NTT) to eliminate ELM by operating L-mode edge with improved core confinement. The SN configuration has more flexibility in shaping by adopting rectangular-shaped TF coils. The limiting normalized beta is 3.56 with wall stabilization and 3.14 without wall. The vertical stability is assured under a reasonable control system. The wetted area on the divertor plates becomes wider in proportion to the larger major radius at the divertor strike points due to the NT configuration. In addition to the major-radius effect, the ``Flux Tune Expansion (FTE)'' is adopted to further reduce the heat load on the divertor plate by factor of 2.6 with a coil current 3 MA. L-mode edge also allows further increase in wetted area. The fusion power of 3 GW is deliverable only at normalized beta 2.1. Therefore this reactor may be operable stably against the serious MHD activities. The CD power for SS operation is 175 MW at Q = 17. AC operation is also possible option. A required HH factor is relatively modest H = 1.12.
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®).
Shocks and currents in stratified atmospheres with a magnetic null point
Tarr, Lucas A.; Linton, Mark
2017-08-01
We use the resistive MHD code LARE (Arber et al 2001) to inject a compressive MHD wavepacket into a stratified atmosphere that has a single magnetic null point, as recently described in Tarr et al 2017. The 2.5D simulation represents a slice through a small ephemeral region or area of plage. The strong gradients in field strength and connectivity related to the presence of the null produce substantially different dynamics compared to the more slowly varying fields typically used in simple sunspot models. The wave-null interaction produces a fast mode shock that collapses the null into a current sheet and generates a set of outward propagating (from the null) slow mode shocks confined to field lines near each separatrix. A combination of oscillatory reconnection and shock dissipation ultimately raise the plasma's internal energy at the null and along each separatrix by 25-50% above the background. The resulting pressure gradients must be balanced by Lorentz forces, so that the final state has contact discontinuities along each separatrix and a persistent current at the null. The simulation demonstrates that fast and slow mode waves localize currents to the topologically important locations of the field, just as their Alfvenic counterparts do, and also illustrates the necessity of treating waves and reconnection as coupled phenomena.
Modular Hamiltonians on the null plane and the Markov property of the vacuum state
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.
Mechanical Forces Exacerbate Periodontal Defects in Bsp-null Mice
Soenjaya, Y.; Foster, B.L.; Nociti, F.H.; Ao, M.; Holdsworth, D.W.; Hunter, G.K.; Somerman, M.J.
2015-01-01
Bone sialoprotein (BSP) is an acidic phosphoprotein with collagen-binding, cell attachment, and hydroxyapatite-nucleating properties. BSP expression in mineralized tissues is upregulated at onset of mineralization. Bsp-null (Bsp-/-) mice exhibit reductions in bone mineral density, bone turnover, osteoclast activation, and impaired bone healing. Furthermore, Bsp-/- mice have marked periodontal tissue breakdown, with a lack of acellular cementum leading to periodontal ligament detachment, extensive alveolar bone and tooth root resorption, and incisor malocclusion. We hypothesized that altered mechanical stress from mastication contributes to periodontal destruction observed in Bsp-/- mice. This hypothesis was tested by comparing Bsp-/- and wild-type mice fed with standard hard pellet diet or soft powder diet. Dentoalveolar tissues were analyzed using histology and micro–computed tomography. By 8 wk of age, Bsp-/- mice exhibited molar and incisor malocclusion regardless of diet. Bsp-/- mice with hard pellet diet exhibited high incidence (30%) of severe incisor malocclusion, 10% lower body weight, 3% reduced femur length, and 30% elevated serum alkaline phosphatase activity compared to wild type. Soft powder diet reduced severe incisor malocclusion incidence to 3% in Bsp-/- mice, supporting the hypothesis that occlusal loading contributed to the malocclusion phenotype. Furthermore, Bsp-/- mice in the soft powder diet group featured normal body weight, long bone length, and serum alkaline phosphatase activity, suggesting that tooth dysfunction and malnutrition contribute to growth and skeletal defects reported in Bsp-/- mice. Bsp-/- incisors also erupt at a slower rate, which likely leads to the observed thickened dentin and enhanced mineralization of dentin and enamel toward the apical end. We propose that the decrease in eruption rate is due to a lack of acellular cementum and associated defective periodontal attachment. These data demonstrate the importance of BSP
Lee, Young-Sam; Gregory, Mark T; Yang, Wei
2014-02-25
DNA polymerase ζ (Pol ζ) is a eukaryotic B-family DNA polymerase that specializes in translesion synthesis and is essential for normal embryogenesis. At a minimum, Pol ζ consists of a catalytic subunit Rev3 and an accessory subunit Rev7. Mammalian Rev3 contains >3,000 residues and is twice as large as the yeast homolog. To date, no vertebrate Pol ζ has been purified for biochemical characterization. Here we report purification of a series of human Rev3 deletion constructs expressed in HEK293 cells and identification of a minimally catalytically active human Pol ζ variant. With a tagged form of an active Pol ζ variant, we isolated two additional accessory subunits of human Pol ζ, PolD2 and PolD3. The purified four-subunit Pol ζ4 (Rev3-Rev7-PolD2-PolD3) is much more efficient and more processive at bypassing a 1,2-intrastrand d(GpG)-cisplatin cross-link than the two-subunit Pol ζ2 (Rev3-Rev7). We show that complete bypass of cisplatin lesions requires Pol η to insert dCTP opposite the 3' guanine and Pol ζ4 to extend the primers.
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.
An improved null model for assessing the net effects of multiple stressors on communities.
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
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.
Directory of Open Access Journals (Sweden)
Matthias Schmid
Full Text Available Regression analysis with a bounded outcome is a common problem in applied statistics. Typical examples include regression models for percentage outcomes and the analysis of ratings that are measured on a bounded scale. In this paper, we consider beta regression, which is a generalization of logit models to situations where the response is continuous on the interval (0,1. Consequently, beta regression is a convenient tool for analyzing percentage responses. The classical approach to fit a beta regression model is to use maximum likelihood estimation with subsequent AIC-based variable selection. As an alternative to this established - yet unstable - approach, we propose a new estimation technique called boosted beta regression. With boosted beta regression estimation and variable selection can be carried out simultaneously in a highly efficient way. Additionally, both the mean and the variance of a percentage response can be modeled using flexible nonlinear covariate effects. As a consequence, the new method accounts for common problems such as overdispersion and non-binomial variance structures.
Agendamento de Políticas Públicas
Directory of Open Access Journals (Sweden)
Rosane Rosa
2011-07-01
Full Text Available Aborda-se o conceito de advocacy e contra-agendamento como uma forma de a Sociedade Civil incluir suas causas na mídia, objetivando a tematização e a possibilidade de transformar-se em política pública. Analisa-se a reportagem “Uma conquista longe das ruas”; resultado de um agendamento compartilhado e que, em muitos aspectos, serve de referência para cobertura de políticas públicas sociais.
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
Labelling of. beta. -endorphin (. beta. -END) and. beta. -lipotropin (. beta. -LPH) by /sup 125/I
Energy Technology Data Exchange (ETDEWEB)
Deby-Dupont, G.; Joris, J.; Franchimont, P. (Universite de Liege (Belgique)); Reuter, A.M.; Vrindts-Gevaert, Y. (Institut des Radioelements, Fleurus (Belgique))
1983-01-01
5 ..mu..g of human ..beta..-endorphin were labelled with 2 mCi /sup 125/I by the chloramine T technique. After two gel filtrations on Sephadex G-15 and on Sephadex G-50 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer was obtained with a specific activity about 150 ..mu..Ci/..mu..g.Kept at + 4/sup 0/C, the tracer remained utilizable for 30 days without loss of immunoreactivity. The labelling with lactoperoxydase and the use of another gel filtration method (filtration on Aca 202) gave a /sup 125/I ..beta..-END tracer with the same immunoreactivity. The binding of this tracer to the antibody of an anti-..beta..-END antiserum diluted at 1/8000 was 32% with a non specific binding of 2%. 5 ..mu..g of human ..beta..-lipotropin were labelled with 0.5 mCi /sup 125/I by the lactoperoxydase method. After two gel filtrations on Sephadex G-25 and on Sephadex G-75 in phosphate buffer with EDTA, Trasylol and mercapto-ethanol, a pure tracer with a specific activity of 140 ..mu..Ci/..mu..g was obtained. It remained utilizable for 30 days when kept at + 4/sup 0/C. Gel filtration on Aca 202 did not give good purification, while gel filtration on Aca 54 was good but slower than on Sephadex G-75. The binding to antibody in absence of unlabelled ..beta..-LPH was 32% for an anti-..beta..-LPH antiserum diluted at 1/4000. The non specific binding was 2.5%.
Zhu, Hui; Bhattarai, Hitesh; Yan, Han-Guang; Shuman, Stewart; Glickman, Michael S
2012-12-21
Mycobacteria exploit nonhomologous end-joining (NHEJ) to repair DNA double-strand breaks. The core NHEJ machinery comprises the homodimeric DNA end-binding protein Ku and DNA ligase D (LigD), a modular enzyme composed of a C-terminal ATP-dependent ligase domain (LIG), a central 3'-phosphoesterase domain (PE), and an N-terminal polymerase domain (POL). LigD POL is proficient at adding templated and nontemplated deoxynucleotides and ribonucleotides to DNA ends in vitro and is the catalyst in vivo of unfaithful NHEJ events involving nontemplated single-nucleotide additions to blunt DSB ends. Here, we identify two mycobacterial proteins, PolD1 and PolD2, as stand-alone homologues of the LigD POL domain. Biochemical characterization of PolD1 and PolD2 shows that they resemble LigD POL in their monomeric quaternary structures, their ability to add templated and nontemplated nucleotides to primer-templates and blunt ends, and their preference for rNTPs versus dNTPs. Deletion of polD1, polD2, or both from a Mycobacterium smegmatis strain carrying an inactivating mutation in LigD POL failed to reveal a role for PolD1 or PolD2 in templated nucleotide additions during NHEJ of 5'-overhang DSBs or in clastogen resistance. Whereas our results document the existence and characteristics of new stand-alone members of the LigD POL family of RNA/DNA polymerases, they imply that other polymerases can perform fill-in synthesis during mycobacterial NHEJ.
International Nuclear Information System (INIS)
Amaral, L.B.D.; Pinto, J.C.M.; Linhares, E.; Linhares, Estevao
1981-01-01
There are three important indications for the early diagnosis of pregnancy through the determination of the beta sub-unit of chorionic gonadotrophin using radioimmunoassay: 1) some patient's or doctor's anxiety to discover the problem; 2) when it will be necessary to employ diagnostic or treatment procedures susceptible to affect the ovum; and 3) in the differential diagnosis of amenorrhoea, uterine hemorrhage and abdominal tumors. Other user's are the diagnosis of missed absortion, and the diagnosis and follow-up of chrorioncarcinoma. The AA. studied 200 determinations of plasma beta-HCG, considering the main difficulties occuring in the clinical use of this relevant laboratory tool in actual Obstetrics. (author) [pt
Relation between the 2{nu}{beta}{beta} and 0{nu}{beta}{beta} nuclear matrix elements
Energy Technology Data Exchange (ETDEWEB)
Vogel, Petr [Kellogg Radiation Laboratory, Caltech, Pasadena, CA 91125 (United States); Simkovic, Fedor [Department of Nuclear Physics and Biophysics, Comenius University, Mlynska dolina F1, SK-84248 Bratislava (Slovakia)
2011-12-16
A formal relation between the GT part of the nuclear matrix elements M{sub GT}{sup 0{nu}} of 0{nu}{beta}{beta} decay and the closure matrix elements M{sub cl}{sup 2{nu}} of 2{nu}{beta}{beta} decay is established. This relation is based on the integral representation of these quantities in terms of their dependence on the distance r between the two nucleons undergoing transformation. We also discuss the difficulties in determining the correct values of the closure 2{nu}{beta}{beta} decay matrix elements.
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.
Konijn, Elly A.; van de Schoot, Rens; Winter, Sonja D.; Ferguson, Christopher J.
2015-01-01
The present paper argues that an important cause of publication bias resides in traditional frequentist statistics forcing binary decisions. An alternative approach through Bayesian statistics provides various degrees of support for any hypothesis allowing balanced decisions and proper null
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.
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
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?
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.
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
deHart, Gregory W; Healy, Kevin E; Jones, Jonathan C R
2003-02-01
Analyses of mice with targeted deletions in the genes for alpha3 and beta1 integrin suggest that the alpha3beta1 integrin heterodimer likely determines the organization of the extracellular matrix within the basement membrane of skin. Here we tested this hypothesis using keratinocytes derived from alpha3 integrin-null mice. We have compared the organizational state of laminin-5, a ligand of alpha3beta1 integrin, in the matrix of wild-type keratinocytes with that of laminin-5 in the matrix of alpha3 integrin-null cells. Laminin-5 distributes diffusely in arc structures in the matrix of wild-type mouse keratinocytes, whereas laminin-5 is organized into linear, spike-like arrays by the alpha3 integrin-null cells. The fact that alpha3 integrin-null cells are deficient in their ability to assemble a proper laminin-5 matrix is also shown by their failure to remodel laminin-5 when plated onto surfaces coated with purified laminin-5 protein. In sharp contrast, wild-type keratinocytes organize exogenously added laminin-5 into discrete ring-like organizations. These findings led us next to assess whether differences in laminin-5 organization in the matrix of the wild-type and alpha3 integrin-null cells impact cell behavior. Our results indicate that alpha3 integrin-null cells are more motile than their wild-type counterparts and leave extensive trails of laminin-5 over the surface on which they move. Moreover, HEK 293 cells migrate significantly more on the laminin-5-rich matrix derived from the alpha3 integrin-null cells than on the wild-type keratinocyte laminin-5 matrix. In addition, alpha3 integrin-null cells show low strength of adhesion to surfaces coated with purified laminin-5 compared to wild-type cells although both the wild type and the alpha3 integrin-null keratinocytes adhere equally strongly to laminin-5 that has been organized into arrays by other epithelial cells. These data suggest: (1) that alpha3beta1 integrin plays an important role in determining the
Ingeniero, político, economista, inventor
Directory of Open Access Journals (Sweden)
Jimena Montaña Cuéllar
2001-01-01
Full Text Available Técnica y utopía. Biografía intelectual y política de Alejandro López, 1876-1940. Alberto Mayor Mora. Fondo Editorial Universidad Eafit, colección Cielos de Arena, Medellín, 2001, 621 págs., il.
Directory of Open Access Journals (Sweden)
Alvaro H. Cifuentes G.
2015-04-01
Full Text Available RESUMEN Si un candidato desea ser elegido, las técnicas de marketing aplicadas a la política, le son imprescindibles. El marketing político (Politing es el análisis metódico de los diferentes segmentos que integran el ámbito político de una sociedad y de los factores que puedan modificarlos. Se aplican al candidato, a los votantes, al análisis de la publicidad política, a los simpatizantes, a desconocedores del partido y a los indecisos. Los candidatos colombianos lo están aplicando, y compañías nuestras exportan servicios de asesoría de países suramericanos.Promocionar un candidato implica estructurar una compañía tal como una empresa, aplicando técnicas de ventas, de fijación de cuotas y de planeación estratégica.
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.
International Nuclear Information System (INIS)
Reiss, H.R.
1986-01-01
Certain nuclear beta decay transitions normally inhibited by angular momentum or parity considerations can be induced to occur by the application of an electromagnetic field. Such decays can be useful in the controlled production of power, and in fission waste disposal
Trichoderma .beta.-glucosidase
Dunn-Coleman, Nigel; Goedegebuur, Frits; Ward, Michael; Yao, Jian
2006-01-03
The present invention provides a novel .beta.-glucosidase nucleic acid sequence, designated bgl3, and the corresponding BGL3 amino acid sequence. The invention also provides expression vectors and host cells comprising a nucleic acid sequence encoding BGL3, recombinant BGL3 proteins and methods for producing the same.
International Nuclear Information System (INIS)
Rich, B.L.
1986-01-01
Measurements of beta and/or nonpenetrating exposure results is complicated and past techniques and capabilities have resulted in significant inaccuracies in recorded results. Current developments have resulted in increased capabilities which make the results more accurate and should result in less total exposure to the work force. Continued development of works in progress should provide equivalent future improvements
Directory of Open Access Journals (Sweden)
R Jha
2014-09-01
Full Text Available Thalassemia is a globin gene disorder that results in a diminished rate of synthesis of one or more of the globin chains. About 1.5% of the global population (80 to 90 million people are carriers of beta Thalassemia. More than 200 mutations are described in beta thalassemia. However not all mutations are common in different ethnic groups. The only effective way to reduce burden of thalassemia is to prevent birth of homozygotes. Diagnosis of beta thalassemia can be done by fetal DNA analysis for molecular defects of beta thalassemia or by fetal blood analysis. Hematopoietic stem cell transplantation is the only available curative approach for Thalassemia. Many patients with thalassemia in underdeveloped nations die in childhood or adolescence. Programs that provide acceptable care, including transfusion of safe blood and supportive therapy including chelation must be established.DOI: http://dx.doi.org/10.3126/jpn.v4i8.11609 Journal of Pathology of Nepal; Vol.4,No. 8 (2014 663-671
International Nuclear Information System (INIS)
Piepke, A.
2005-01-01
The experimental observation of neutrino oscillations and thus neutrino mass and mixing gives a first hint at new particle physics. The absolute values of the neutrino mass and the properties of neutrinos under CP-conjugation remain unknown. The experimental investigation of the nuclear double beta decay is one of the key techniques for solving these open problems
Beta cell adaptation in pregnancy
DEFF Research Database (Denmark)
Nielsen, Jens Høiriis
2016-01-01
Pregnancy is associated with a compensatory increase in beta cell mass. It is well established that somatolactogenic hormones contribute to the expansion both indirectly by their insulin antagonistic effects and directly by their mitogenic effects on the beta cells via receptors for prolactin...... and growth hormone expressed in rodent beta cells. However, the beta cell expansion in human pregnancy seems to occur by neogenesis of beta cells from putative progenitor cells rather than by proliferation of existing beta cells. Claes Hellerström has pioneered the research on beta cell growth for decades...... in the expansion of the beta cell mass in human pregnancy, and the relative roles of endocrine factors and nutrients....
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
pyNSMC: A Python Module for Null-Space Monte Carlo Uncertainty Analysis
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.
The data-driven null models for information dissemination tree in social networks
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.
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
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
Directory of Open Access Journals (Sweden)
María Belén Albornoz
2010-05-01
Full Text Available Este artículo problematiza la acepción de lo público en el espacio virtual que surge en la blogosfera política ecuatoriana en el contexto de la Asamblea Nacional Constituyente. A partir del análisis de la extensión de la política a los lugares virtuales, se aborda la blogosfera como proyecto político y la tecnología como formas de ordenamiento del mundo que la sociedad estabiliza. Se considera a la blogosfera política un espacio público regulado con la capacidad de ordenar y clasificar el mundo virtual por medio de dispositivos sociales, políticos y tecnológicos. Finalmente se propone el estudio del nuevo espacio público virtual desde un enfoque tecno-social que dé cuenta del entorno virtual como espacio formador de conductas.This article problematizes the acceptance of the public in the virtual space emerging in the Ecuadorian political blogosphere, in the context of the National Constitutional Assembly. Beginning with an analysis of the spread of politics to virtual spaces, the blogosphere is approached as a political project, and technology as ways of ordering the world that society stabilizes. The political blogosphere is taken to be a regulated public space with the ability to order and classify the virtual world by means of social, political and technological tools. Finally, the study of this new virtual public space from a techno-social focus is proposed, taking into account virtual surroundings as a space in which conducts are formed.
Enhancer SINEs Link Pol III to Pol II Transcription in Neurons
Directory of Open Access Journals (Sweden)
Cristina Policarpi
2017-12-01
Full Text Available Summary: Spatiotemporal regulation of gene expression depends on the cooperation of multiple mechanisms, including the functional interaction of promoters with distally located enhancers. Here, we show that, in cortical neurons, a subset of short interspersed nuclear elements (SINEs located in the proximity of activity-regulated genes bears features of enhancers. Enhancer SINEs (eSINEs recruit the Pol III cofactor complex TFIIIC in a stimulus-dependent manner and are transcribed by Pol III in response to neuronal depolarization. Characterization of an eSINE located in proximity to the Fos gene (FosRSINE1 indicated that the FosRSINE1-encoded transcript interacts with Pol II at the Fos promoter and mediates Fos relocation to Pol II factories, providing an unprecedented molecular link between Pol III and Pol II transcription. Strikingly, knockdown of the FosRSINE1 transcript induces defects of both cortical radial migration in vivo and activity-dependent dendritogenesis in vitro, demonstrating that FosRSINE1 acts as a strong enhancer of Fos expression in diverse physiological contexts. : Spatiotemporal regulation of gene expression requires the interaction between promoters and distally located enhancers. Policarpi et al. identify a subset of SINEs that functions as enhancers for activity-dependent neuronal genes. The enhancer SINE FosRSINE1 regulates Fos transcription and is necessary for both activity-dependent dendritogenesis and proper brain development. Keywords: neuroscience, epigenetics, transcription, enhancers, SINEs, neuronal activity, neuronal development
Misleading Betas: An Educational Example
Chong, James; Halcoussis, Dennis; Phillips, G. Michael
2012-01-01
The dual-beta model is a generalization of the CAPM model. In the dual-beta model, separate beta estimates are provided for up-market and down-market days. This paper uses the historical "Anscombe quartet" results which illustrated how very different datasets can produce the same regression coefficients to motivate a discussion of the…
Subtleties in the beta-function calculation of N = 1 supersymmetric gauge theories
Energy Technology Data Exchange (ETDEWEB)
Cherchiglia, A.L. [ICEx, Universidade Federal de Minas Gerais, Departamento de Fisica, P.O. Box 702, Belo Horizonte, MG (Brazil); Universidad de Granada, Departamento de Fisica Teorica y del Cosmos and CAFPE, Granada (Spain); Sampaio, Marcos [ICEx, Universidade Federal de Minas Gerais, Departamento de Fisica, P.O. Box 702, Belo Horizonte, MG (Brazil); Hiller, B. [CFisUC, Universidade de Coimbra, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, Coimbra (Portugal); Scarpelli, A.P.B. [Setor Tecnico-Cientifico, Departamento de Policia Federal, Sao Paulo (Brazil)
2016-02-15
We investigate some peculiarities in the calculation of the two-loop beta function of N = 1 supersymmetric models which are intimately related to the so-called ''anomaly puzzle''. There is an apparent paradox when the computation is performed in the framework of the covariant derivative background field method. In this formalism, there is obtained a finite two-loop effective action, although a non-null coefficient for the beta function is achieved by means of the renormalized two-point function in the background field. We show that if the standard background field method is used, this two-point function has a divergent part which allows for the calculation of the beta function via the renormalization constants, as usual. Therefore, we conjecture that this paradox has its origin in the covariant supergraph formalism itself, possibly being an artifact of the rescaling anomaly. (orig.)
Subtleties in the beta-function calculation of N = 1 supersymmetric gauge theories
International Nuclear Information System (INIS)
Cherchiglia, A.L.; Sampaio, Marcos; Hiller, B.; Scarpelli, A.P.B.
2016-01-01
We investigate some peculiarities in the calculation of the two-loop beta function of N = 1 supersymmetric models which are intimately related to the so-called ''anomaly puzzle''. There is an apparent paradox when the computation is performed in the framework of the covariant derivative background field method. In this formalism, there is obtained a finite two-loop effective action, although a non-null coefficient for the beta function is achieved by means of the renormalized two-point function in the background field. We show that if the standard background field method is used, this two-point function has a divergent part which allows for the calculation of the beta function via the renormalization constants, as usual. Therefore, we conjecture that this paradox has its origin in the covariant supergraph formalism itself, possibly being an artifact of the rescaling anomaly. (orig.)
Shiina, T; Kawasaki, A; Nagao, T; Kurose, H
2000-09-15
The beta(1)-adrenergic receptor (beta(1)AR) shows the resistance to agonist-induced internalization. As beta-arrestin is important for internalization, we examine the interaction of beta-arrestin with beta(1)AR with three different methods: intracellular trafficking of beta-arrestin, binding of in vitro translated beta-arrestin to intracellular domains of beta(1)- and beta(2)ARs, and inhibition of betaAR-stimulated adenylyl cyclase activities by beta-arrestin. The green fluorescent protein-tagged beta-arrestin 2 translocates to and stays at the plasma membrane by beta(2)AR stimulation. Although green fluorescent protein-tagged beta-arrestin 2 also translocates to the plasma membrane, it returns to the cytoplasm 10-30 min after beta(1)AR stimulation. The binding of in vitro translated beta-arrestin 1 and beta-arrestin 2 to the third intracellular loop and the carboxyl tail of beta(1)AR is lower than that of beta(2)AR. The fusion protein of beta-arrestin 1 with glutathione S-transferase inhibits the beta(1)- and beta(2)AR-stimulated adenylyl cyclase activities, although inhibition of the beta(1)AR-stimulated activity requires a higher concentration of the fusion protein than that of the beta(2)AR-stimulated activity. These results suggest that weak interaction of beta(1)AR with beta-arrestins explains the resistance to agonist-induced internalization. This is further supported by the finding that beta-arrestin can induce internalization of beta(1)AR when beta-arrestin 1 does not dissociate from beta(1)AR by fusing to the carboxyl tail of beta(1)AR.
Políticas activas en las prestaciones por desempleo
Gil Jiménez, Javier
2016-01-01
El presente trabajo explica el tema de las políticas activas y políticas activas en las prestaciones por desempleo, tanto a nivel nacional como internacional. Para explicarlo se definen las políticas activas y sus funciones, tanto de formación, orientación y reinserción laboral. También se hace mención a las reformas llevadas a cabo en las diferentes políticas y el surgimiento de nuevos programas como función de políticas activas encaminadas a la reinserción laboral. Departamento de Derech...
Low-beta investment strategies
Korn, Olaf; Kuntz, Laura-Chloé
2015-01-01
This paper investigates investment strategies that exploit the low-beta anomaly. Although the notion of buying low-beta stocks and selling high-beta stocks is natural, a choice is necessary with respect to the relative weighting of high-beta stocks and low-beta stocks in the investment portfolio. Our empirical results for US large-cap stocks show that this choice is very important for the risk-return characteristics of the resulting portfolios and their sensitivities to common risk factors. W...
Neutrophil beta-2 microglobulin: an inflammatory mediator
DEFF Research Database (Denmark)
Bjerrum, O W; Nissen, Mogens Holst; Borregaard, N
1990-01-01
Beta-2 microglobulin (beta 2m) constitutes the light invariant chain of HLA class I antigen, and is a constituent of mobilizable compartments of neutrophils. Two forms of beta 2m exist: native beta 2m and proteolytically modified beta 2m (Des-Lys58-beta 2m), which shows alpha mobility in crossed ...
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
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
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
Averaged null energy condition and difference inequalities in quantum field theory
International Nuclear Information System (INIS)
Yurtsever, U.
1995-01-01
For a large class of quantum states, all local (pointwise) energy conditions widely used in relativity are violated by the renormalized stress-energy tensor of a quantum field. In contrast, certain nonlocal positivity constraints on the quantum stress-energy tensor might hold quite generally, and this possibility has received considerable attention in recent years. In particular, it is now known that the averaged null energy condition, the condition that the null-null component of the stress-energy tensor integrated along a complete null geodesic is non-negative for all states, holds quite generally in a wide class of spacetimes for a minimally coupled scalar field. Apart from the specific class of spacetimes considered (mainly two-dimensional spacetimes and four-dimensional Minkowski space), the most significant restriction on this result is that the null geodesic over which the average is taken must be achronal. Recently, Ford and Roman have explored this restriction in two-dimensional flat spacetime, and discovered that in a flat cylindrical space, although the stress energy tensor itself fails to satisfy the averaged null energy condition (ANEC) along the (nonachronal) null geodesics, when the ''Casimir-vacuum'' contribution is subtracted from the stress-energy the resulting tensor does satisfy the ANEC inequality. Ford and Roman name this class of constraints on the quantum stress-energy tensor ''difference inequalities.'' Here I give a proof of the difference inequality for a minimally coupled massless scalar field in an arbitrary (globally hyperbolic) two-dimensional spacetime, using the same techniques as those we relied on to prove the ANEC in an earlier paper with Wald. I begin with an overview of averaged energy conditions in quantum field theory
International Nuclear Information System (INIS)
Galindo, A.; Pascual, P.
1967-01-01
These notes represent a series of lectures delivered by the authors in the Junta de Energia Nuclear, during the Spring term of 1965. They were devoted to graduate students interested in the Theory of Elementary Particles. Special emphasis was focussed into the computational problems. Chapter I is a review of basic principles (Dirac equation, transition probabilities, final state interactions.) which will be needed later. In Chapter II the four-fermion punctual Interaction is discussed, Chapter III is devoted to the study of beta-decay; the main emphasis is given to the deduction of the formulae corresponding to electron-antineutrino correlation, electron energy spectrum, lifetimes, asymmetry of electrons emitted from polarized nuclei, electron and neutrino polarization and time reversal invariance in beta decay. In Chapter IV we deal with the decay of polarized muons with radiative corrections. Chapter V is devoted to an introduction to C.V.C. theory. (Author)
Directory of Open Access Journals (Sweden)
Origa Raffaella
2010-05-01
Full Text Available Abstract Beta-thalassemias are a group of hereditary blood disorders characterized by anomalies in the synthesis of the beta chains of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individuals. The total annual incidence of symptomatic individuals is estimated at 1 in 100,000 throughout the world and 1 in 10,000 people in the European Union. Three main forms have been described: thalassemia major, thalassemia intermedia and thalassemia minor. Individuals with thalassemia major usually present within the first two years of life with severe anemia, requiring regular red blood cell (RBC transfusions. Findings in untreated or poorly transfused individuals with thalassemia major, as seen in some developing countries, are growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, development of masses from extramedullary hematopoiesis, and skeletal changes that result from expansion of the bone marrow. Regular transfusion therapy leads to iron overload-related complications including endocrine complication (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands, dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Main clinical features in these patients are hypertrophy of erythroid marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities and typical facial changes, gallstones, painful leg ulcers and increased predisposition to thrombosis. Thalassemia minor is clinically asymptomatic but some subjects may have moderate anemia. Beta-thalassemias are caused by point mutations or, more rarely
DEFF Research Database (Denmark)
Løvborg, Leif; Gaffney, C. F.; Clark, P. A.
1985-01-01
Experimental and/or theoretical estimates are presented concerning, (i) attenuation within the sample of beta and gamma radiation from the soil, (ii) the gamma dose within the sample due to its own radioactivity, and (iii) the soil gamma dose in the proximity of boundaries between regions...... of differing radioactivity. It is confirmed that removal of the outer 2 mm of sample is adequate to remove influence from soil beta dose and estimates are made of the error introduced by non-removal. Other evaluations include variation of the soil gamma dose near the ground surface and it appears...... that the present practice of avoiding samples above a depth of 0.3 m may be over-cautious...
Energy Technology Data Exchange (ETDEWEB)
Galindo, A; Pascual, P
1967-07-01
These notes represent a series of lectures delivered by the authors in the Junta de Energia Nuclear, during the Spring term of 1965. They were devoted to graduate students interested in the Theory of Elementary Particles. Special emphasis was focussed into the computational problems. Chapter I is a review of basic principles (Dirac equation, transition probabilities, final state interactions.) which will be needed later. In Chapter II the four-fermion punctual Interaction is discussed, Chapter III is devoted to the study of beta-decay; the main emphasis is given to the deduction of the formulae corresponding to electron-antineutrino correlation, electron energy spectrum, lifetimes, asymmetry of electrons emitted from polarized nuclei, electron and neutrino polarization and time reversal invariance in beta decay. In Chapter IV we deal with the decay of polarized muons with radiative corrections. Chapter V is devoted to an introduction to C.V.C. theory. (Author)
Regulation of beta cell replication
DEFF Research Database (Denmark)
Lee, Ying C; Nielsen, Jens Høiriis
2008-01-01
Beta cell mass, at any given time, is governed by cell differentiation, neogenesis, increased or decreased cell size (cell hypertrophy or atrophy), cell death (apoptosis), and beta cell proliferation. Nutrients, hormones and growth factors coupled with their signalling intermediates have been...... suggested to play a role in beta cell mass regulation. In addition, genetic mouse model studies have indicated that cyclins and cyclin-dependent kinases that determine cell cycle progression are involved in beta cell replication, and more recently, menin in association with cyclin-dependent kinase...... inhibitors has been demonstrated to be important in beta cell growth. In this review, we consider and highlight some aspects of cell cycle regulation in relation to beta cell replication. The role of cell cycle regulation in beta cell replication is mostly from studies in rodent models, but whether...
International Nuclear Information System (INIS)
Okamura, S.; Matsuoka, K.; Nishimura, K.
1994-09-01
High beta experiments were performed in the low-aspect-ratio helical device CHS with the volume-averaged equilibrium beta up to 2.1 %. These values (highest for helical systems) are obtained for high density plasmas in low magnetic field heated with two tangential neutral beams. Confinement improvement given by means of turning off gas puffing helped significantly to make high betas. Magnetic fluctuations increased with increasing beta, but finally stopped to increase in the beta range > 1 %. The coherent modes appearing in the magnetic hill region showed strong dependence on the beta values. The dynamic poloidal field control was applied to suppress the outward plasma movement with the plasma pressure. Such an operation gave fixed boundary operations of high beta plasmas in helical systems. (author)
International Nuclear Information System (INIS)
Adams, S.F.
1992-01-01
It was over 30 years between the first observation of the enigmatic process of beta decay and the first postulation of the neutrino. It took a further 26 years until the first neutrino was detected and yet another 27 until the electroweak theory was confirmed by the discovery of W and Z particles. This article traces some of the puzzles and paradoxes associated with the history of the neutrino. (author)
DEFF Research Database (Denmark)
Kristensen, Bent Bruun; Madsen, Ole Lehrmann; Møller-Pedersen, Birger
In object-oriented programming, a program execution is viewed as a physical model of some real or imaginary part of the world. A language supporting object-oriented programming must therefore contain comprehensive facilities for modeling phenomena and concepts form the application domain. Many...... applications in the real world consist of objects carrying out sequential processes. Coroutines may be used for modeling objects that alternate between a number of sequential processes. The authors describe coroutines in BETA...
DEFF Research Database (Denmark)
Madsen, Ole Lehrmann
1999-01-01
Component technologies based on binary units of independent production are some of the most important contributions to software architecture and reuse during recent years. Especially the COM technologies and the CORBA standard from the Object Management Group have contributed new and interesting...... principles for software architecture, and proven to be useful in parctice. In this paper ongoing work with component support in the BETA language is described....
LHCb: $2\\beta_s$ measurement at LHCb
Conti, G
2009-01-01
A measurement of $2\\beta_s$, the phase of the $B_s-\\bar{B_s}$ oscillation amplitude with respect to that of the ${\\rm b} \\rightarrow {\\rm c^{+}}{\\rm W^{-}}$ tree decay amplitude, is one of the key goals of the LHCb experiment with first data. In the Standard Model (SM), $2\\beta_s$ is predicted to be $0.0360^{+0.0020}_{-0.0016} \\rm rad$. The current constraints from the Tevatron are: $2\\beta_{s}\\in[0.32 ; 2.82]$ at 68$\\%$CL from the CDF experiment and $2\\beta_{s}=0.57^{+0.24}_{-0.30}$ from the D$\\oslash$ experiment. Although the statistical uncertainties are large, these results hint at the possible contribution of New Physics in the $B_s-\\bar{B_s}$ box diagram. After one year of data taking at LHCb at an average luminosity of $\\mathcal{L}\\sim2\\cdot10^{32}\\rm cm^{-2} \\rm s^{-1}$ (integrated luminosity $\\mathcal{L}_{\\rm int}\\sim 2 \\rm fb^{-1}$), the expected statistical uncertainty on the measurement is $\\sigma(2\\beta_s)\\simeq 0.03$. This uncertainty is similar to the $2\\beta_s$ value predicted by the SM.
Hernando Bernal.
1998-01-01
Este trabajo pretende hacer una serie de consideraciones que apuntan sobre todo a extraer una definición de lo que es «la política» para el psicoanálisis a partir de una observación que hace Jacques Alain Miller en su texto Lógicas de la vida amorosa sobre cómo Freud introduce una «teoría política» a partir de su texto Psicología de las masas y análisis del yo.En dicho texto Freud hace ver el poder ordenador y apaciguador del amor) significante amo) en la medida en que una masa no es más que ...
Liu, Haiyan; Javaheri, Ali; Godar, Rebecca J; Murphy, John; Ma, Xiucui; Rohatgi, Nidhi; Mahadevan, Jana; Hyrc, Krzysztof; Saftig, Paul; Marshall, Connie; McDaniel, Michael L; Remedi, Maria S; Razani, Babak; Urano, Fumihiko; Diwan, Abhinav
2017-01-01
Obesity-induced diabetes is characterized by hyperglycemia, insulin resistance, and progressive beta cell failure. In islets of mice with obesity-induced diabetes, we observe increased beta cell death and impaired autophagic flux. We hypothesized that intermittent fasting, a clinically sustainable therapeutic strategy, stimulates autophagic flux to ameliorate obesity-induced diabetes. Our data show that despite continued high-fat intake, intermittent fasting restores autophagic flux in islets and improves glucose tolerance by enhancing glucose-stimulated insulin secretion, beta cell survival, and nuclear expression of NEUROG3, a marker of pancreatic regeneration. In contrast, intermittent fasting does not rescue beta-cell death or induce NEUROG3 expression in obese mice with lysosomal dysfunction secondary to deficiency of the lysosomal membrane protein, LAMP2 or haplo-insufficiency of BECN1/Beclin 1, a protein critical for autophagosome formation. Moreover, intermittent fasting is sufficient to provoke beta cell death in nonobese lamp2 null mice, attesting to a critical role for lysosome function in beta cell homeostasis under fasting conditions. Beta cells in intermittently-fasted LAMP2- or BECN1-deficient mice exhibit markers of autophagic failure with accumulation of damaged mitochondria and upregulation of oxidative stress. Thus, intermittent fasting preserves organelle quality via the autophagy-lysosome pathway to enhance beta cell survival and stimulates markers of regeneration in obesity-induced diabetes.
Hans Kelsen: pensador político
Directory of Open Access Journals (Sweden)
Sara Lagi
2011-01-01
Full Text Available Hasta la publicación de Sobre la esencia y el valor de la democracia, Hans Kelsen era solo conocido como experto en derecho público. El valor de este artículo de Lagi radica en rescatar de la obra kelseniana un aspecto casi por completo olvidado por la crítica, a saber, sus análisis sobre el significado y las características de la democracia parlamentaria en los Estados modernos. Se aborda la cuestión no solo desde el debate teórico sino también desde su contexto histórico¿político. La teoría política de Kelsen es considerada una parte integral de su doctrina central, presentada en Teoría pura del derecho, su obra más conspicua. Un análisis del trabajo sobre la esencia y el valor de la democracia nos restituye la imagen de un Kelsen como original pensador político. Se analizan las dos ediciones de Sobre la esencia y el valor de la democracia (1920¿1929 con estos propósitos: comprender por qué decidió dedicarse a la teoría de la democracia un teórico que rigurosamente defendió la separación de la esfera jurídica respecto de la historia, la filosofía y la política; y por qué no se limitó a explicar la esencia de la democracia sino que decidió concentrarse en clarificar qué se entiende por valor de la democracia.
Vacuum Nuller Testbed (VNT) Performance, Characterization and Null Control: Progress Report
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.
A Null Space Control of Two Wheels Driven Mobile Manipulator Using Passivity Theory
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.
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
Vacuum nuller testbed (VNT) performance, characterization and null control: progress report
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.
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
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.
Enantioselective synthesis of alpha,beta-disubstituted-beta-amino acids.
Sibi, Mukund P; Prabagaran, Narayanasamy; Ghorpade, Sandeep G; Jasperse, Craig P
2003-10-01
Highly diastereoselective and enantioselective addition of N-benzylhydroxylamine to imides 17 and 20-30 produces alpha,beta-trans-disubstituted N-benzylisoxazolidinones 19 and 31-41. These reactions proceed in 60-96% ee with 93-99% de's using 5 mol % of Mg(NTf2)2 and ligand 18. The product isoxazolidinones can be hydrogenolyzed directly to provide alpha,beta-disubstituted-beta-amino acids.
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)
Maxwell, Yang-Mills, Weyl and eikonal fields defined by any null shear-free congruence
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.
The (2, 0) superalgebra, null M-branes and Hitchin's system
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.
Beta measurement evaluation and upgrade
International Nuclear Information System (INIS)
Swinth, K.L.; Rathbun, L.A.; Roberson, P.L.; Endres, G.W.R.
1986-01-01
This program focuses on the resolution of problems associated with the field measurement of the beta dose component at Department of Energy (DOE) facilities. The change in DOE programs, including increased efforts in improved waste management and decontamination and decommissioning (D and D) of facilities, coupled with beta measurement problems identified at Three Mile Island has increased the need to improve beta measurements. In FY 1982, work was initiated to provide a continuing effort to identify problems associated with beta dose assessment at DOE facilities. The problems identified resulted in the development of this program. The investigation includes (1) an assessment of measurement systems now in use, (2) development of improved calibration systems and procedures, (3) application of innovative beta dosimetry concepts, (4) investigation of new instruments or concepts for monitoring and spectroscopy, and (5) development of recommendations to assure an adequate beta measurement program within DOE facilities
Elecciones 2003: spots políticos y cultura política
Concepción Virriel
2004-01-01
El presente trabajo aborda el tema de las elecciones federales de 2003, en especial el fenómeno del abstencionismo. Para ello se vincula el comportamiento electoral en dichas elecciones con la cultura política, en donde los aspectos básicos son la cultura del fraude heredada de los gobiernos priístas y la redefinición de los partidos políticos ante una nueva coyuntura, y cómo éstos aspectos influyeron en la forma de comunicarse mediante sus spots. El análisis de dichos spots comprende el anál...
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.
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.
Noncolocated Time-Reversal MUSIC: High-SNR Distribution of Null Spectrum
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.
In vivo time-gated diffuse correlation spectroscopy at quasi-null source-detector separation.
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.
Conditional Betas and Investor Uncertainty
Fernando D. Chague
2013-01-01
We derive theoretical expressions for market betas from a rational expectation equilibrium model where the representative investor does not observe if the economy is in a recession or an expansion. Market betas in this economy are time-varying and related to investor uncertainty about the state of the economy. The dynamics of betas will also vary across assets according to the assets' cash-flow structure. In a calibration exercise, we show that value and growth firms have cash-flow structures...
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)
Dynamic returns of beta arbitrage
Nascimento, Mafalda
2017-01-01
This thesis studies the patterns of the abnormal returns of the beta strategy. The topic can be helpful for professional investors, who intend to achieve a better performance in their portfolios. Following the methodology of Lou, Polk, & Huang (2016), the COBAR measure is computed in order to determine the levels of beta arbitrage in the market in each point in time. It is argued that beta arbitrage activity can have impact on the returns of the beta strategy. In fact, it is demonstrated that...
Integration of BETA with Eclipse
DEFF Research Database (Denmark)
Andersen, Peter; Madsen, Ole Lehrmann; Enevoldsen, Mads Brøgger
2004-01-01
This paper presents language interoperability issues appearing in order to implement support for the BETA language in the Java-based Eclipse integrated development environment. One of the challenges is to implement plug-ins in BETA and be able to load them in Eclipse. In order to do this, some fo...... it is possible to implement plug-ins in BETA and even inherit from Java classes. In the paper the two approaches are described together with part of the mapping from BETA to Java class files. http://www.sciencedirect.com/science/journal/15710661...
Simultaneous beta and gamma spectroscopy
Farsoni, Abdollah T.; Hamby, David M.
2010-03-23
A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.
Prototype Theory Based Feature Representation for PolSAR Images
Huang Xiaojing; Yang Xiangli; Huang Pingping; Yang Wen
2016-01-01
This study presents a new feature representation approach for Polarimetric Synthetic Aperture Radar (PolSAR) image based on prototype theory. First, multiple prototype sets are generated using prototype theory. Then, regularized logistic regression is used to predict similarities between a test sample and each prototype set. Finally, the PolSAR image feature representation is obtained by ensemble projection. Experimental results of an unsupervised classification of PolSAR images show that our...
International Nuclear Information System (INIS)
Dayal, A.
2010-01-01
The paralyzed zebrafish strain relaxed carries a null mutation for the skeletal muscle dihydropyridine receptor (DHPR) [beta]1a subunit. The lack of [beta]1a not only impedes functional [alpha]1S membrane expression but also precludes the skeletal muscle-specific ultrastructural arrangement of DHPRs into tetrads opposite ryanodine receptor (RyR1), coherent with the absence of skeletal muscle excitation-contraction (EC) coupling. With the plethora of experimental approaches feasible with zebrafish model organism and importantly with the [beta]1-null mutation having a monogenetic inheritance and because of the survival of the relaxed larvae for some days, we were able to establish the zebrafish relaxed as an expression system. Linking in vitro to in vivo observations, a clear differentiation between the major functional roles of [beta] subunits in EC coupling was feasible. The skeletal muscle [beta]1a subunit was able to restore all parameters of EC coupling upon expression in relaxed myotubes and larvae. Expression of the phylogenetically closest isoform to [beta]1a, the cardiac/neuronal [beta]2a subunit or the most distant neuronal [beta]M from the housefly in relaxed myotubes and larvae was likewise able to fully restore [alpha]1S triad targeting and facilitate charge movement. However, efficient tetrad formation and thus intact DHPR-RyR1 coupling was exclusively promoted by the [beta]1a isoform. Consequently, we postulated a model according to which [beta]1a acts as a unique allosteric modifier of [alpha]1S conformation crucial for skeletal muscle EC coupling. Therefore, unique structural elements in [beta]1a must be present which endow it with this exclusive property. Earlier, a unique hydrophobic heptad repeat motif (LVV) in the [beta]1a C-terminus was postulated by others to be essential for skeletal muscle EC coupling. We wanted to address the question if the proposed [beta]1a heptad repeat motif could be an active element of the DHPR-RyR1 signal transduction
Identification of active anti-inflammatory principles of beta- beta ...
African Journals Online (AJOL)
chromatography. Components of the extracts were identified by thin layer chromatography (TLC) scanner and UV-visible spectroscopy, using scopoletin as standard. Results: ... basic coumarin skeleton ring structure reduce ... Figure 2: Thin-layer chromatogram: (1) Ethanol extract; (2) Dichloromethane fraction; (3) Beta-beta.
Improved limits on beta(-) and beta(-) decays of Ca-48
Czech Academy of Sciences Publication Activity Database
Bakalyarov, A.; Balysh, A.; Barabash, AS.; Beneš, P.; Briancon, C.; Brudanin, V. B.; Čermák, P.; Egorov, V.; Hubert, F.; Hubert, P.; Korolev, NA.; Kosjakov, VN.; Kovalík, Alojz; Lebedev, NA.; Novgorodov, A. F.; Rukhadze, NI.; Štekl, NI.; Timkin, VV.; Veleshko, IE.; Vylov, T.; Umatov, VI.
2002-01-01
Roč. 76, č. 9 (2002), s. 545-547 ISSN 0021-3640 Institutional research plan: CEZ:AV0Z1048901 Keywords : beta decay * double beta decay * Ca-48 Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.483, year: 2002
Desarrollo vocacional y política pública
Watts, Anthony G.
2000-01-01
El trabajo analiza la base para el interés político en los servicios de desarrollo vocacional, y la manera en la cual esta base está siendo fortalecida por las actuales transformaciones en el trabajo y en el desarrollo vocacional. Se exploran los papeles potenciales de la política pública en los servicios de desarrollo vocacional así como las formas en las que dichos servicios pueden influenciar el proceso de la creación de políticas. Se identifican una gama de temas de política relacionados ...
Política, violencia y literatura
Directory of Open Access Journals (Sweden)
Kohut, Karl
2002-06-01
Full Text Available Tomando como punto de partida la opinión general de que América Latina es el continente violento por excelencia y la hipótesis defendida por Ariel Dorfman (1972 se analiza aquí la cuestión de la violencia política, ciñéndose a la literatura de la segunda mitad del siglo XX. Tras discutir las definiciones (divergentes de la violencia propuestas por la filosofía política, se pasa a una fenomenología de la violencia en la literatura, examinando hasta qué punto y en qué sentido ésta sería el carácter distintivo de la literatura latinoamericana. Finalmente, se analiza la metarreflexión sobre la violencia política en la literatura ficcional, centrándose en tres puntos: (1 el (presunto ser violento del mundo latinoamericano, (2 la violencia estatal, y (3 la violencia de la resistencia. Se constata, entre otras cosas, que ha habido una tendencia a atacar la violencia estatal y defender la de la resistencia; tendencia comprensible en tiempos de dictadura, pero que se vuelve problemática bajo una democracia. Dos preguntas cierran este trabajo: hasta qué punto la violencia es un fenómeno de la cultura, que crece en su mismo seno, y no un fenómeno extracultural dirigido contra ella, y hasta dónde la libertad individual y la seguridad cívica pueden ser conciliadas, punto que ha ocupado un lugar central en la discusión internacional después de los acontecimientos del 11 de septiembre.
Lee, I Y; Nissen, S L; Rosazza, J P
1997-01-01
beta-Hydroxy-beta-methylbutyric acid (HMB) has been shown to increase strength and lean mass gains in humans undergoing resistance-exercise training. HMB is currently marketed as a calcium salt of HMB, and thus, environmentally sound and inexpensive methods of manufacture are being sought. This study investigates the microbial conversion of beta-methylbutyric acid (MBA) to HMB by cultures of Galactomyces reessii. Optimal concentrations of MBA were in the range of 5 to 20 g/liter for HMB produ...
Directory of Open Access Journals (Sweden)
Germán Posada
1961-10-01
Full Text Available La polémica empezó con el artículo de Hernando Téllez, hace veinte días. Con el pretexto de defender a los escritores de su propia generación, a quienes, según él, se viene acusando sistemáticamente de producir una literatura desarraigada y ausente de la vida nacional, Téllez se lanzó a combatir las teorías de " nacionalismo literario'' que actualmente se agitan en Colombia.
Directory of Open Access Journals (Sweden)
Marquessuel Dantas de Souza
2017-09-01
Full Text Available A presente resenha se refere ao interessante texto de Simone Weil (Note sur la suppression générale des partis politiques - de 1940, escrito em Londres, traduzido e publicado pela iniciativa audaciosa da Editora Ayiné. Originalmente publicado na coletânea intitulada ÉCRITS DE LONDRES et dernières lettres - Éditions Gallimard (1957, este texto apresenta de forma singular o que significa um partido político; algo de muita importância para e na vida social do homem moderno.
Directory of Open Access Journals (Sweden)
Hernando Bernal.
1998-09-01
Full Text Available Este trabajo pretende hacer una serie de consideraciones que apuntan sobre todo a extraer una definición de lo que es «la política» para el psicoanálisis a partir de una observación que hace Jacques Alain Miller en su texto Lógicas de la vida amorosa sobre cómo Freud introduce una «teoría política» a partir de su texto Psicología de las masas y análisis del yo.En dicho texto Freud hace ver el poder ordenador y apaciguador del amor significante amo en la medida en que una masa no es más que el amor uniendo a muchas personas y reiterado en cada una de ellas. Las fuerzas armadas y la Iglesia son un buen ejemplo de ello.Pero a pesar de la cohesión amorosa de la humanidad por el poder unificante del amor, resta siempre un malestar. El malestar que persiste en la cultura testimonia del fracaso del amor para resolver el empuje del hombre a satisfacerse con el mal. El significante amo no parece entonces solucionar la paradoja del goce. De aquí que preguntarse sobre adónde vaya el goce en el orden social sea también, para el psicoanálisis, una cuestión política. Jacques- Alain Miller observa, en su texto Lógicas de la vida amorosa, cómo, a partir de la Psicología de las masas y análisis del yo, se puede extraer de Freud una «teoría política», que se vincula muy estrechamente con el amor. Esto porque La Psicología de las masas... enseña sobre el poder ordenador y apaciguador del amor, o mejor, del significante «amor» como significante Amo, lo que se puede escribir de la siguiente manera con ayuda de la «teoría de los discursos» o «teoría del vínculo social» de Lacan.
Políticas de reconhecimento uma novidade das políticas sociais do PT?
Directory of Open Access Journals (Sweden)
Krischke, Paulo Jose Duval da Silva
2004-01-01
Full Text Available O presente trabalho levanta a hipótese de que as ações de governo do PT estão inovando significativamente na necessária convergência (cf. Fraser, 1999; Honnetch, 2003 entre as tradicionais políticas de redistribuição sócio-econômica, e uma nova diretriz de reconhecimento das diferenças sócio-políticas e culturais. O argumento retoma a trajetória sindical do PT e os efeitos das políticas participativas, nas mudanças da cultura política em várias partes do país. Entre esses efeitos, o crescente apoio à democracia parece relacionar-se ao reconhecimento do direito à diferença e ao pluralismo - principalmente entre a juventude e naqueles locais onde o PT tem governado na última década
International Nuclear Information System (INIS)
Hadjiloucas, S; Walker, G C; Bowen, J W; Zafiropoulos, A
2009-01-01
The THz water content index of a sample is defined and advantages in using such metric in estimating a sample's relative water content are discussed. The errors from reflectance measurements performed at two different THz frequencies using a quasi-optical null-balance reflectometer are propagated to the errors in estimating the sample water content index.
Partial null astigmatism-compensated interferometry for a concave freeform Zernike mirror
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.
The Harm Done to Reproducibility by the Culture of Null Hypothesis Significance Testing.
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.
High Contrast Vacuum Nuller Testbed (VNT) Contrast, Performance and Null Control
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.
Modelling the electromechanical interactions in a null-flux EDS Maglev system
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
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.
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.
Exact null distributions of quadratic distribution-free statistics for two-way classification
Wiel, van de M.A.
2004-01-01
Abstract We present new techniques for computing exact distributions of `Friedman-type¿ statistics. Representing the null distribution by a generating function allows for the use of general, not necessarily integer-valued rank scores. Moreover, we use symmetry properties of the multivariate
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.
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)
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.
A Coding of Real Null Four-Momenta into World-Sheet Co-ordinates
Fairlie, David B.
2008-01-01
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 co-ordinates on the world sheet. This identification arises consistently from different approaches to the problem.
A Panel Test of Purchasing Power Parity Under the Null of Stationarity
Hunter, J; Simpson, M
2001-01-01
Purchasing Power Parity (PPP) is tested using a sample of real exchange rate data for twelve European countries. Acknowledging that Augmented Dickey Fuller tests have low power, we apply a Panel test that considers the null of stationarity and corrects for serial dependence using a non-parametric kernel based method.
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.
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.
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.
High contrast vacuum nuller testbed (VNT) contrast, performance, and null control
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.
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.
Development of IR single mode optical fibers for DARWIN-nulling interferometry
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
The Need for Nuance in the Null Hypothesis Significance Testing Debate
Häggström, Olle
2017-01-01
Null hypothesis significance testing (NHST) provides an important statistical toolbox, but there are a number of ways in which it is often abused and misinterpreted, with bad consequences for the reliability and progress of science. Parts of contemporary NHST debate, especially in the psychological sciences, is reviewed, and a suggestion is made…
Integrable structures and the quantization of free null initial data for gravity
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.
Reduced infarct size in neuroglobin-null mice after experimental stroke in vivo
DEFF Research Database (Denmark)
Raida, Zindy; Hundahl, Christian Ansgar; Kelsen, Jesper
2012-01-01
Neuroglobin is considered to be a novel important pharmacological target in combating stroke and neurodegenerative disorders, although the mechanism by which this protection is accomplished remains an enigma. We hypothesized that if neuroglobin is directly involved in neuroprotection, then perman......, then permanent cerebral ischemia would lead to larger infarct volumes in neuroglobin-null mice than in wild-type mice....
Interpretation of Chinese Overt and Null Embedded Arguments by English-Speaking Learners
Zhao, Lucy Xia
2012-01-01
It has been proposed that external interfaces are vulnerable to residue optionality, whereas pure syntax and internal interfaces are acquirable in second language (L2) acquisition (Sorace, 2005, 2011; Sorace and Filiaci, 2006). The proposal was tested in this article through the interpretation of overt and null embedded arguments in L2 Chinese…
Simple Fourier optics formalism for high-angular-resolution systems and nulling interferometry.
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.
Hamilton-Jacobi formalism for Podolsky's electromagnetic theory on the null-plane
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.
What Constitutes Science and Scientific Evidence: Roles of Null Hypothesis Testing
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…
Dinâmica Institucional, Políticas Públicas e o Desempenho Político Ambiental Brasileiro
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Diego de Freitas Rodrigues
2011-12-01
Full Text Available Este estudo buscou analisar os efeitos da interdependência entre instituições políticas e modelos de desenvolvimento no desempenho de políticas ambientais no Brasil. A hipótese central do trabalho é que, dada a interdependência entre os organismos responsáveis pelas políticas ambientais e padrões de desenvolvimento pouco responsivos à complexidade ambiental, ocorre uma dispersão de poder decisório incentivando o modelo de desenvolvimento de alto carbono. Além de revisão da literatura em Políticas Públicas e Economia Ecológica, foram operacionalizadas (1 uma análise do desenho político-institucional brasileiro e (2 o quadro de gastos públicos do governo federal brasileiro com meio ambiente. Dois resultados foram observados: 1o o desenho e as competências das instituições políticas responsáveis pela formulação e implementação de políticas públicas interferem na maior eficiência de políticas ambientais; 2o quanto maior a abertura institucional, maior a tendência de paralisia decisória na formulação e implementação de políticas públicas ambientais.
Zou, L.
2006-01-01
The issue of 'best-beta' arises as soon as potential errors in the Sharpe-Lintner-Black capital asset pricing model (CAPM) are acknowledged. By incorporating a target variable into the investor preferences, this study derives a best-beta CAPM (BCAPM) that maintains the CAPM's theoretical appeal and
Borcea, R; Aysto, J; Caurier, E; Dendooven, P; Doring, J; Gierlik, M; Gorska, M; Grawe, H; Hellstrom, M; Janas, Z; Jokinen, A; Karny, M; Kirchner, R; La Commara, M; Langanke, K; Martinez-Pinedo, G; Mayet, P; Nieminen, A; Nowacki, F; Penttila, H; Plochocki, A; Rejmund, M; Roeckl, E; Schlegel, C; Schmidt, K; Schwengner, R; Sawicka, M
2001-01-01
The proton-rich isotope Cu-56 was produced at the GSI On-Line Mass Separator by means of the Si-28(S-32, p3n) fusion-evaporation reaction. Its beta -decay properties were studied by detecting beta -delayed gamma rays and protons. A half-Life of 93 +/- 3 ms was determined for Cu-56. Compared to the
BETA SPECTRA. I. Negatrons spectra
International Nuclear Information System (INIS)
Grau Malonda, A.; Garcia-Torano, E.
1978-01-01
Using the Fermi theory of beta decay, the beta spectra for 62 negatrons emitters have been computed introducing a correction factor for unique forbidden transitions. These spectra are plotted vs. energy, once normal i sed, and tabulated with the related Fermi functions. The average and median energies are calculated. (Author)
International Nuclear Information System (INIS)
Sheffield, J.
1982-01-01
This note lists some of the possible causes of beta limitation in tokamak and discusses what is known and what is involved in investigating them. The motivation for preparing this note is the observed degradation of confinement with increasing beta poloidal β/sub p/ and beam power P/sub b/ in ISX-B
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
International Nuclear Information System (INIS)
Rabiti, Cristian; Alfonsi, Andrea; Cogliati, Joshua Joseph; Mandelli, Diego; Kinoshita, Robert Arthur; Wang, Congjian; Maljovec, Daniel Patrick; Talbot, Paul William
2016-01-01
This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.
Energy Technology Data Exchange (ETDEWEB)
Rabiti, Cristian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Alfonsi, Andrea [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kinoshita, Robert Arthur [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wang, Congjian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Maljovec, Daniel Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Talbot, Paul William [Idaho National Lab. (INL), Idaho Falls, ID (United States)
2016-02-01
This documents the release of the Risk Analysis Virtual Environment (RAVEN) code. A description of the RAVEN code is provided, and discussion of the release process for the M2LW-16IN0704045 milestone. The RAVEN code is a generic software framework to perform parametric and probabilistic analysis based on the response of complex system codes. RAVEN is capable of investigating the system response as well as the input space using Monte Carlo, Grid, or Latin Hyper Cube sampling schemes, but its strength is focused toward system feature discovery, such as limit surfaces, separating regions of the input space leading to system failure, using dynamic supervised learning techniques. RAVEN has now increased in maturity enough for the Beta 1.0 release.
Croce, Gramsci e a "autonomia da política"
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Álvaro Bianchi
2007-11-01
Full Text Available Na reflexão que Gramsci desenvolveu nos Quaderni del carcere, o tema da autonomia da política ocupa uma importante posição. Foi com base nessa reflexão que Gramsci desenvolveu sua pesquisa a respeito de política e da possibilidade de uma ciência política. Segundo Benedetto Croce, cabia a Nicolau Maquiavel o mérito de ter afirmado pela primeira vez a autonomia da política. Para Croce, essa autonomia permitia estabelecer uma distinção radical entre ética e política e entre "filosofia da política" e "ciência empírica da política". Gramsci tomou criticamente a reflexão croceana como ponto de partida de sua leitura de Maquiavel. O reconhecimento da autonomia da política implicava que esta não poderia ser reduzida à religião ou à ética. Como campo do conhecimento e como atividade, a ciência política e a política tinham regras próprias, que as distinguiam de outras formas do conhecimento e da atividade humana. Mas tal "autonomia" não implicava, para o marxista sardo, uma separação radical entre política e moral. Por essa razão, Gramsci encontrava em Maquiavel um precursor da filosofia da práxis em sentido pleno, ou seja, o criador de uma "ciência-ação revolucionária".
Cultura Política na Antiguidade
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José Petrúcio Farias Júnior
2009-06-01
Full Text Available
Pretendemos discutir nesse artigo algumas implicações do termo cultura política na Antiguidade, especificamente, na sociedade romana imperial. Dessa forma, acreditamos que as considerações que apresentaremos a seguir contribuam para reflexão da utilização desse termo, produto das investigações contemporâneas, sobre os estudos das sociedades antigas. Para a historiadora Profa. Dra. Margarida Maria de Carvalho, tais reflexões representam ainda uma lacuna na historiografia concernente a essa temática. Isso posto, discorreremos, inicialmente, sobre o conceito de cultura e seus desdobramentos para, em seguida, refletirmos sobre o viés interpretativo que fundamenta estudos históricos que se desenvolvem sob o beneplácito da linha de pesquisa intitulada História e Cultura Política.
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Manoel Mendonça Filho
2012-01-01
Full Text Available O artigo trata as questões do "Estado" e da "Política" partindo do exemplo concreto do processo de institucionalização, no Brasil, de práticas profissionais em psicologia reconhecidas como Análise Institucional (vertente grupalista francesa consideravelmente difundida nos últimos 20 anos. Trabalho para expor uma face menos visível da judicialização que funciona ao nível das concepções, crenças e valores entre os operadores dos equipamentos onde se materializam as políticas públicas engendradas pelo excesso legalista. Dentre as modalidades desse apego à lei, toma-se em análise aquela mais próxima de nossas práticas de funcionalismo público marcando o índice de grau máximo de sua institucionalização: a aceitação consensual da competência como critério de legitimidade na operação dos "instrumentos da violência institucional".
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Todorov Tzevetan
1998-06-01
Full Text Available ¿Qué es un intelectual? Por lo que a mi respecta, limito el uso de este término de la siguiente manera: es un estudioso o un artista (categoria que incluye a los escritores que no se contenta con realizar trabajos cientificos o con la creación de una obra de arte, que no se contenta, por lo tanto, con una méra búsqueda de lo verdadero y con un méro desarrollo de lo bello, sino que siente asimismo comprometido con la noción de bienestar público, con los valores de la sociedad en la que vive, es alguien que participa en el debate sobre esos mismos valores. El intelectual así entendido se halla muy lejos del artista o del estudioso a quienes no preocupan en absoluto las dimensiones políticas o éticas de sus obras; muy lejos también, del predicador o del político profesional, que no crean obra alguna.
Interactions between two beta-sheets. Energetics of beta/beta packing in proteins.
Chou, K C; Némethy, G; Rumsey, S; Tuttle, R W; Scheraga, H A
1986-04-20
The analysis of the interactions between regularly folded segments of the polypeptide chain contributes to an understanding of the energetics of protein folding. Conformational energy-minimization calculations have been carried out to determine the favorable ways of packing two right-twisted beta-sheets. The packing of two five-stranded beta-sheets was investigated, with the strands having the composition CH3CO-(L-Ile)6-NHCH3 in one beta-sheet and CH3CO-(L-Val)6-NHCH3 in the other. Two distinct classes of low-energy packing arrangements were found. In the class with lowest energies, the strands of the two beta-sheets are aligned nearly parallel (or antiparallel) with each other, with a preference for a negative orientation angle, because this arrangement corresponds to the best complementary packing of the two twisted saddle-shaped beta-sheets. In the second class, with higher interaction energies, the strands of the two beta-sheets are oriented nearly perpendicular to each other. While the surfaces of the two beta-sheets are not complementary in this arrangement, there is good packing between the corner of one beta-sheet and the interior part of the surface of the other, resulting in a favorable energy of packing. Both classes correspond to frequently observed orientations of beta-sheets in proteins. In proteins, the second class of packing is usually observed when the two beta-sheets are covalently linked, i.e. when a polypeptide strand passes from one beta-sheet to the other, but we have shown here that a large contribution to the stabilization of this packing arrangement arises from noncovalent interactions.
Reversing hypomyelination in BACE1-null mice with Akt-DD overexpression.
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.
Orexin Receptor Antagonism Improves Sleep and Reduces Seizures in Kcna1-null Mice.
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
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,
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
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
Derivatives of the Incomplete Beta Function
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Robert J. Boik
1998-03-01
Full Text Available The incomplete beta function is defined as where Beta(p, q is the beta function. Dutka (1981 gave a history of the development and numerical evaluation of this function. In this article, an algorithm for computing first and second derivatives of Ix,p,q with respect to p and q is described. The algorithm is useful, for example, when fitting parameters to a censored beta, truncated beta, or a truncated beta-binomial model.
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.
Human PrimPol activity is enhanced by RPA.
Martínez-Jiménez, María I; Lahera, Antonio; Blanco, Luis
2017-04-10
Human PrimPol is a primase belonging to the AEP superfamily with the unique ability to synthesize DNA primers de novo, and a non-processive DNA polymerase able to bypass certain DNA lesions. PrimPol facilitates both mitochondrial and nuclear replication fork progression either acting as a conventional TLS polymerase, or repriming downstream of blocking lesions. In vivo assays have shown that PrimPol is rapidly recruited to sites of DNA damage by interaction with the human replication protein A (RPA). In agreement with previous findings, we show here that the higher affinity of RPA for ssDNA inhibits PrimPol activities in short ssDNA templates. In contrast, once the amount of ssDNA increases up to a length in which both proteins can simultaneously bind ssDNA, as expected during replicative stress conditions, PrimPol and RPA functionally interact, and their binding capacities are mutually enhanced. When using M13 ssDNA as template, RPA stimulated both the primase and polymerase activities of PrimPol, either alone or in synergy with Polε. These new findings supports the existence of a functional PrimPol/RPA association that allows repriming at the exposed ssDNA regions formed in the leading strand upon replicase stalling.
O conceito de liberdade política em Montesquieu
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Maria Beatriz Nizza da Silva
1969-06-01
Full Text Available O primeiro passo na análise do conceito de liberdade política, tal como êle se nos apresenta em De l'esprit des lois, deverá assina-lar uma diferença, fundamental para Montesquieu, entre "liberdade filosófica" e "liberdade política".
Los spots factor, esencial del marketing político
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María de Jesús Origel Gutiérrez
2000-01-01
Full Text Available EI objetivo del presente trabajo es demostrar que en las elecciones presidenciales de julio de 2000, la forma de hacer política en México se modificó al introducir en las campanas electorales el marketing político y nuevas estrategias de comunicación, en especial los spots televisivos
International Nuclear Information System (INIS)
La Haye, R.J.; Lao, L.L.; Strait, E.J.; Taylor, T.S.
1997-01-01
The maximum operational high beta in single-null divertor (SND) long pulse tokamak discharges in the DIII-D tokamak with a cross-sectional shape similar to the proposed International Thermonuclear Experimental Reactor (ITER) device is found to be limited by the onset of resistive instabilities that have the characteristics of neoclassically destabilized tearing modes. There is a soft limit due to the onset of an m/n=3/2 rotating tearing mode that saturates at low amplitude and a hard limit at slightly higher beta due to the onset of an m/n=2/1 rotating tearing mode that grows, slows down and locks. By operating at higher density and thus collisionality, the practical beta limit due to resistive tearing modes approaches the ideal magnetohydrodynamic (MHD) limit. (author). 15 refs, 4 figs
Development of beta reference radiations
International Nuclear Information System (INIS)
Wan Zhaoyong; Cai Shanyu; Li Yanbo; Yin Wei; Feng Jiamin; Sun Yuhua; Li Yongqiang
1997-09-01
A system of beta reference radiation has been developed, that is composed of 740 MBq 147 Pm beta source, 74 MBq and 740 MBq 90 Sr + 90 Y β sources, compensation filters, a source handling tool, a source jig, spacing bars, a shutter, a control unit and a beta dose meter calibration stand. For 740 MBq 147 Pm and 74 MBq 90 Sr + 90 Y beta reference radiations with compensation filters and 740 MBq 90 Sr + 90 Y beta reference radiation without compensation filter, at 20 cm, 30 cm and 30 cm distance separately; the residual energy of maximum is 0.14 MeV, 1.98 MeV and 2.18 MeV separately; the absorbed dose to tissue D (0.07) is 1.547 mGy/h (1996-05-20), 5.037 mGy/h (1996-05-10) and 93.57 mGy/h (1996-05-15) separately; the total uncertainty is 3.0%, 1.7% and 1.7% separately. For the first and the second beta reference radiation, the dose rate variability in the area of 18 cm diameter in the plane perpendicular to the beta-ray beam axis is within +-6% and +-3% separately. (3 refs., 2 tabs., 8 figs.)
A semiconductor beta ray spectrometer
International Nuclear Information System (INIS)
Bom, V.R.
1987-01-01
Measurement of energy spectra of beta particles emitted from nuclei in beta-decay processes provides information concerning the mass difference of these nuclei between initial and final state. Moreover, experimental beta spectra yield information on the feeding of the levels in the daughter nucleus. Such data are valuable in the construction and checking of the level schemes. This thesis describes the design, construction, testing and usage of a detector for the accurate measurement of the mentioned spectra. In ch. 2 the design and construction of the beta spectrometer, which uses a hyper-pure germanium crystal for energy determination, is described. A simple wire chamber is used to discriminate beta particles from gamma radiation. Disadvantages arise from the large amounts of scattered beta particles deforming the continua. A method is described to minimize the scattering. In ch. 3 some theoretical aspects of data analysis are described and the results of Monte-Carlo simulations of the summation of annihilation radiation are compared with experiments. Ch. 4 comprises the results of the measurements of the beta decay energies of 103-108 In. 87 refs.; 34 figs.; 7 tabs
BETA (Bitter Electromagnet Testing Apparatus)
Bates, Evan M.; Birmingham, William J.; Rivera, William F.; Romero-Talamas, Carlos A.
2017-10-01
The Bitter Electromagnet Testing Apparatus (BETA) is a 1-Tesla (T) prototype of the 10-T Adjustable Long Pulse High-Field Apparatus (ALPHA). These water-cooled resistive magnets use high DC currents to produce strong uniform magnetic fields. Presented here is the successful completion of the BETA project and experimental results validating analytical magnet designing methods developed at the Dusty Plasma Laboratory (DPL). BETA's final design specifications will be highlighted which include electromagnetic, thermal and stress analyses. The magnet core design will be explained which include: Bitter Arcs, helix starters, and clamping annuli. The final version of the magnet's vessel and cooling system are also presented, as well as the electrical system of BETA, which is composed of a unique solid-state breaker circuit. Experimental results presented will show the operation of BETA at 1 T. The results are compared to both analytical design methods and finite element analysis calculations. We also explore the steady state maximums and theoretical limits of BETA's design. The completion of BETA validates the design and manufacturing techniques that will be used in the succeeding magnet, ALPHA.
1985-10-01
Refueling Under Armor ......................... 34 Page i ,t .J APPENDICES A. POL Unit Missions and Capabilities ....................... A-I B. Roster...refueling Open versus closed port refueling Requirement for Refueling Under Armor Robotic refueler V % Page 34 S.< ’p. ". APPgeDI A-"" • " ’ ’ POL " it
A política da Igreja Universal e seus reflexos nos campos religioso e político brasileiros
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Oro Ari Pedro
2003-01-01
Full Text Available Este texto versa sobre a inserção da Igreja Universal do Reino de Deus (IURD na política nacional e seus efeitos nos campos religioso e político. Em razão da eficácia de seu carisma institucional, a Universal procedeu, dentro do próprio grupo religioso, a uma ressemantização do ato de votar em particular e da percepção da política em geral, inscrevendo-os em sua lógica religiosa. Isso é uma importante chave explicativa para o elevado grau de fidelidade de votos e o êxito político cada vez maior constatado nas últimas eleições. Ademais, a prática política da Universal está produzindo um efeito mimético em outra igrejas evangélicas, que tendem a imitar seu modelo de fazer política. Sua inserção política, sobretudo por intermédio do Partido Liberal, não passa despercebida pelos partidos, constituindo-se, assim, em um ator relevante na atual conjuntura política brasileira.
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
Experiments on double beta decay
Energy Technology Data Exchange (ETDEWEB)
Busto, J [Neuchatel Univ. (Switzerland). Inst. de Physique
1996-11-01
The Double Beta Decay, and especially ({beta}{beta}){sub 0{nu}} mode, is an excellent test of Standard Model as well as of neutrino physics. From experimental point of view, a very large number of different techniques are or have been used increasing the sensitivity of this experiments quite a lot (the factor of 10{sup 4} in the last 20 years). In future, in spite of several difficulties, the sensitivity would be increased further, keeping the interest of this very important process. (author) 4 figs., 5 tabs., 21 refs.
Preventive Effects of Beta-Hydroxy-Beta-Methyl Butyrate
N. Ravanbakhsh; N. Torabi; M. Foadoddini
2016-01-01
Aims: One of the major factors in sudden cardiac arrest is the initiation and continuation of deadly arrhythmias during ischemia. It is known that beta-hydroxy-beta-methylbutyrate (HMB) has useful effects such as anti-inflammatory and anti-apoptosis effects in the skeletal muscles. The aim of this study was to investigate the preventive effects of HMB on the ventricular arrhythmias due to the ischemia. Materials & Methods: In the experimental study, 30 Wistar male rats were randomly div...
Dosimetry of {beta} extensive sources; Dosimetria de fuentes {beta} extensas
Energy Technology Data Exchange (ETDEWEB)
Rojas C, E.L.; Lallena R, A.M. [Departamento de Fisica Moderna, Universidad de Granada, E-18071 Granada (Spain)
2002-07-01
In this work, we have been studied, making use of the Penelope Monte Carlo simulation code, the dosimetry of {beta} extensive sources in situations of spherical geometry including interfaces. These configurations are of interest in the treatment of the called cranealfaringyomes of some synovia leisure of knee and other problems of interest in medical physics. Therefore, its application can be extended toward problems of another areas with similar geometric situation and beta sources. (Author)
SOUTH POL: Revealing the Polarized Southern Sky
Magalhaes, Antonio Mario Mario; Ramírez, Edgar; Ribeiro, Nadili; Seriacopi, Daiane; Rubinho, Marcelo; Ferrari, Tiberio; Rodrigues, Claudia; Schoenell, William; Herpich, Fabio; Pereyra, Antonio
2018-01-01
SOUTH POL will be a survey of the Southern sky in optical polarized light. It will use a newly built polarimeter for T80-S, an 84 cm robotic telescope installed at Cerro Tololo (CTIO), Chile. It will initially cover the sky South of declination -15 deg with a polarimetric accuracy Solar System.The polarimeter has just been commissioned in mid-November, 2017. The data reduction pipeline has already been built. We will describe the instrument and the data reduction, as well as a few of the science cases. The survey is expected to begin midway through the 1st semester of 2018. Both catalog data and raw images will be made available.
Cultura e políticas sociais : uma visão a partir da cultura política
Corrêa, Helena Ariane Borges
2008-01-01
A dissertação parte do questionamento de por que fatores culturais não são considerados na formulação de políticas públicas. Para tanto são analisadas e discutidas duas vertentes tradicionalmente separadas na ciência política: culturalismo e institucionalismo, que aqui serão trabalhadas em um nível de análise menos abstrato, relacionando elementos de cultura política com políticas públicas. Com isto o trabalho procura mostrar a relevância do estudo de fatores culturais em políticas sociais e ...
International Nuclear Information System (INIS)
Newman, D.E.
1975-01-01
Describes an experiment to measure beta decays of the sigma particle. Sigmas produced by stopping a K - beam in a liquid hydrogen target decayed in the following reactions: Kp → Σπ; Σ → Neν. The electron and pion were detected by wire spark chambers in a magnetic spectrometer and by plastic scintillators, and were differentiated by a threshold gas Cherenkov counter. The neutron was detected by liquid scintillation counters. The data (n = 3) shell electrons or the highly excited electrons decay first. Instead, it is suggested that when there are two to five electrons in highly excited states immediately after a heavy ion--atom collision the first transitions to occur will be among highly excited Rydberg states in a cascade down to the 4s, 4p, and 3d-subshells. If one of the long lived states becomes occupied by electrons promoted during the collision or by electrons falling from higher levels, it will not decay until after the valence shell decays. LMM rates calculated to test the methods used are compared to previous works. The mixing coefficients are given in terms of the states 4s4p, 45sp+-, and 5s5p. The applicability of Cooper, Fano, and Prats' discussion of the energies and transition rates of doubly excited states is considered
International Nuclear Information System (INIS)
Fiorini, Ettore
2008-01-01
The importance of neutrinoless Double Beta Decay (DBD) is stressed in view of the recent results of experiments on neutrino oscillations which indicate that the difference between the squared masses of two neutrinos of different flavours is finite [For a recent review including neutrino properties and recent results see: Review of Particle Physics, J. of Phys. G: Nuclear and Particle Physics 33, 1]. As a consequence the mass of at least one neutrino has to be different from zero and it becomes imperative to determine its absolute value. The various experimental techniques to search for DBD are discussed together with the difficult problems of the evaluation of the corresponding nuclear matrix elements. The upper limits on neutrino mass coming from the results of the various experiments are reported together with the indication for a non zero value by one of them not confirmed so far. The two presently running experiments on neutrinoless DBD are briefly described together with the already approved or designed second generation searches aiming to reach the values on the absolute neutrino mass indicated by the results on neutrino oscillations
A Polícia e suas Polícias: Clientela, Hierarquia, Soldado e Bandido
Directory of Open Access Journals (Sweden)
Erika Ferreira de Azevedo
Full Text Available Resumo A polícia militar representa um braço do Estado e apresenta-se para a população de forma contundente, ostensiva e, por vezes, brutal, não só para a sociedade como para ela mesma. Através da Análise Institucional do Discurso, a pesquisa aqui relatada teve como objetivo estudar os efeitos de reconhecimento e desconhecimento das relações no trabalho que permeiam o discurso de soldados da polícia militar: como estes falam de seu trabalho e, através desta fala, posicionam-se e posicionam sua clientela, sua hierarquia, seu objeto de trabalho (os “bandidos” e eles próprios. Buscou-se também analisar que lugar a violência ocupou neste discurso. Dez soldados da polícia militar do Estado de São Paulo foram entrevistados e a transcrição destas estrevistas foi analisada. A partir das análises, é possível refletir sobre a dubiedade do verdadeiro objetivo do trabalho policial, deslizando facilmente do cuidado da população desamparada ao cuidado de si, desamparado sob a pressão da farda.
African Journals Online (AJOL)
raoul
Urothelial tumour samples were obtained from all the 86 patients requiring surgical ..... and/or urine beta HCG appears to be an efficient diagnostic marker for the ..... collected all urothelial tumour specimens for storage, cutting and staining.
Czech Academy of Sciences Publication Activity Database
Šíma, Petr; Vannucci, Luca; Větvička, V.
2017-01-01
Roč. 41, č. 4 (2017), s. 1799-1808 ISSN 1107-3756 Institutional support: RVO:61388971 Keywords : cholesterol * beta-glucans * diet Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.341, year: 2016
Radioisotope indicator, type BETA 2
International Nuclear Information System (INIS)
Duszanski, M.; Pankow, A.; Skwarczynski, B.
1975-01-01
The authors describe a radioisotope indicator, type BETA 2, constructed in the ZKMPW Works to be employed in mines for counting, checking, signalling the presence and positioning of cars, as well as monitoring the state of some other equipment. (author)
Null geodesics and wave front singularities in the Gödel space-time
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.
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.
Zirngibl, Ralph A; Senis, Yotis; Greer, Peter A
2002-04-01
The fps/fes proto-oncogene encodes a cytoplasmic protein tyrosine kinase implicated in growth factor and cytokine receptor signaling and thought to be essential for the survival and terminal differentiation of myeloid progenitors. Fps/Fes-null mice were healthy and fertile, displayed slightly reduced numbers of bone marrow myeloid progenitors and circulating mature myeloid cells, and were more sensitive to lipopolysaccharide (LPS). These phenotypes were rescued using a fps/fes transgene. This confirmed that Fps/Fes is involved in, but not required for, myelopoiesis and that it plays a role in regulating the innate immune response. Bone marrow-derived Fps/Fes-null macrophages showed no defects in granulocyte-macrophage colony-stimulating factor-, interleukin 6 (IL-6)-, or IL-3-induced activation of signal transducer and activator of transcription 3 (Stat3) and Stat5A or LPS-induced degradation of I kappa B or activation of p38, Jnk, Erk, or Akt.
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.
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)
Adrian, Mark L.; Wendel, D. E.
2012-01-01
We investigate observations of intense bursts of electromagnetic wave energy in association with the thin current layers of turbulent magnetosheath reconnection. These observed emissions - typically detected in the layers immediately outside of the current layer proper - form two distinct types: (i) broadband emissions that extend continuously to lOs of Hertz; and (ii) structured bursts of emitted energy that occur above 80-Hz, often displaying features reminiscent of absorption bands and are observed near the local minima in the magnetic field. We present detailed analyses of these intense bursts of electromagnetic energy and quantify their proximity to X-IO-nulls and magnetic spine connected null pairs, as well as their correlation - if any - to the amount of magnetic energy converted by the process of magnetic reconnection.
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
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...
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.
A mycobacterial smc null mutant is proficient in DNA repair and long-term survival.
Güthlein, Carolin; Wanner, Roger M; Sander, Peter; Böttger, Erik C; Springer, Burkhard
2008-01-01
SMC (structural maintenance of chromosomes) proteins play fundamental roles in various aspects of chromosome organization and dynamics, including repair of DNA damage. Mutant strains of Mycobacterium smegmatis and Mycobacterium tuberculosis defective in SMC were constructed. Surprisingly, inactivation of smc did not result in recognizable phenotypes in hallmark assays characteristic for the function of these genes. This is in contrast to data for smc null mutants in other species.
A Mycobacterial smc Null Mutant Is Proficient in DNA Repair and Long-Term Survival▿
Güthlein, Carolin; Wanner, Roger M.; Sander, Peter; Böttger, Erik C.; Springer, Burkhard
2007-01-01
SMC (structural maintenance of chromosomes) proteins play fundamental roles in various aspects of chromosome organization and dynamics, including repair of DNA damage. Mutant strains of Mycobacterium smegmatis and Mycobacterium tuberculosis defective in SMC were constructed. Surprisingly, inactivation of smc did not result in recognizable phenotypes in hallmark assays characteristic for the function of these genes. This is in contrast to data for smc null mutants in other species.
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.
Potential of balloon payloads for in flight validation of direct and nulling interferometry concepts
Demangeon, Olivier; Ollivier, Marc; Le Duigou, Jean-Michel; Cassaing, Frédéric; Coudé du Foresto, Vincent; Mourard, Denis; Kern, Pierre; Lam Trong, Tien; Evrard, Jean; Absil, Olivier; Defrere, Denis; Lopez, Bruno
2010-07-01
While the question of low cost / low science precursors is raised to validate the concepts of direct and nulling interferometry space missions, balloon payloads offer a real opportunity thanks to their relatively low cost and reduced development plan. Taking into account the flight capabilities of various balloon types, we propose in this paper, several concepts of payloads associated to their flight plan. We also discuss the pros and cons of each concepts in terms of technological and science demonstration power.
Czech Academy of Sciences Publication Activity Database
Zahradníček, Oldřich; Horáček, I.; Tucker, A. S.
2012-01-01
Roč. 221, č. 3 (2012), s. 195-208 ISSN 0021-8782 R&D Projects: GA ČR(CZ) GAP305/12/1766 Grant - others:GA AV ČR(CZ) KJB601110910 Program:KJ Institutional research plan: CEZ:AV0Z50390703 Institutional support: RVO:68378041 Keywords : cusps * gecko * null generation teeth Subject RIV: EA - Cell Biology Impact factor: 2.357, year: 2012
Vascular Response to Intra-arterial Injury in the Thrombospondin-1 Null Mouse
Budhani, Faisal; Leonard, Katherine A.; Bergdahl, Andreas; Gao, Jimin; Lawler, Jack; Davis, Elaine C.
2007-01-01
Thrombospondin-1 (TSP-1) is a multifunctional, extracellular matrix protein that has been implicated in the regulation of smooth muscle cell proliferation, migration and differentiation during vascular development and injury. Vascular injury in wildtype and TSP-1 null mice was carried out by insertion of a straight spring guidewire into the femoral artery via a muscular arterial branch. Blood flow was restored after the muscular branch was ligated. The injury completely denuded the endotheliu...
Null strings and complex Einstein-Maxwell fields with cosmological constant
International Nuclear Information System (INIS)
Garcia, A.; Plebanski, J.F.; Robinson, I.
1977-01-01
Previous results of Plebanski and Robinson (Phys. Rev. Lett.; 37:493 (1976)) concerning left-degenerate Einstein-flat complex space-times and preliminary results concerning the electromagnetic field, are here generalized and worked out in some detail for the system of Einstein-Maxwell equations with a cosmological constant. On the assumption that there exists a congruence of totally null surfaces, the system is reduced to a pair of equations for the two unknown functions. (author)
The root infinitive stage in a null subject language: Romance in the Balkans
Directory of Open Access Journals (Sweden)
Larisa Avram
2007-01-01
Full Text Available The aim of the present paper is to determine which early non-finite verbal form is the Root Infinitive analogue in Romanian, an Inflection-licensed null subject language. In particular, we investigate whether the RI-analogue is the imperative, as predicted by Salustri and Hyams’s (2003 hypothesis, or whether it is a language specific underspecified form, overused during the early stages of acquisition, as predicted by Wexler et al. (2004.
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.
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.
Null Geodesic Congruences, Asymptotically-Flat Spacetimes and Their Physical Interpretation.
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.
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, inclu...
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.
Congruences of null strings in complex space-times and some Cauchy--Kovalevski-like problems
International Nuclear Information System (INIS)
Robinson, I.; Rozga, K.
1984-01-01
It is shown that a problem of construction of a local congruence of null strings is equivalent to a natural Cauchy--Kovalevski-like problem, related to an equation for a spinor field k/sub A/ defining the congruence. Initial data are specified on two-dimensional submanifolds. In left-conformally-flat spaces, the solution of that problem exists for arbitrary initial data
Chronic Toxoplasma gondii in Nurr1-Null Heterozygous Mice Exacerbates Elevated Open Field Activity
Eells, Jeffrey B.; Varela-Stokes, Andrea; Guo-Ross, Shirley X.; Kummari, Evangel; Smith, Holly M.; Cox, Erin; Lindsay, David S.
2015-01-01
Latent infection with Toxoplasma gondii is common in humans (approximately 30% of the global population) and is a significant risk factor for schizophrenia. Since prevalence of T. gondii infection is far greater than prevalence of schizophrenia (0.5-1%), genetic risk factors are likely also necessary to contribute to schizophrenia. To test this concept in an animal model, Nurr1-null heterozygous (+/-) mice and wild-type (+/+) mice were evaluate using an emergence test, activity in an open fie...
Internalizing Null Extraterrestrial "Signals": An Astrobiological App for a Technological Society
Chaisson, Eric J.
2014-01-01
One of the beneficial outcomes of searching for life in the Universe is that it grants greater awareness of our own problems here on Earth. Lack of contact with alien beings to date might actually comprise a null "signal" pointing humankind toward a viable future. Astrobiology has surprising practical applications to human society; within the larger cosmological context of cosmic evolution, astrobiology clarifies the energetic essence of complex systems throughout the Universe, including tech...
On the dependence of energy confinement on elongation in Single Null divertor plasmas
International Nuclear Information System (INIS)
Weisen, H.; Martin, Y.; Moret, J. M.; Others
2002-03-01
An analysis of the effect of magnetic geometry on heat flux in a wide range of Single Null diverted discharge configurations with 1.5 κ ∼ 74, based on the configurations in the study. This is very close to dependences from the ITER database for discharge conditions, such as ELMy H-modes, obtained from a large number of experiments in various tokamak devices. (author)
Bi-dimensional null model analysis of presence-absence binary matrices.
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
Null Geodesics and Strong Field Gravitational Lensing in a String Cloud Background
International Nuclear Information System (INIS)
Iftikhar, Sehrish; Sharif, M.
2015-01-01
This paper is devoted to studying two interesting issues of a black hole with string cloud background. Firstly, we investigate null geodesics and find unstable orbital motion of particles. Secondly, we calculate deflection angle in strong field limit. We then find positions, magnifications, and observables of relativistic images for supermassive black hole at the galactic center. We conclude that string parameter highly affects the lensing process and results turn out to be quite different from the Schwarzschild black hole
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
On the Penrose inequality for dust null shells in the Minkowski spacetime of arbitrary dimension
International Nuclear Information System (INIS)
Mars, Marc; Soria, Alberto
2012-01-01
A particular, yet relevant, case of the Penrose inequality involves null shells propagating in the Minkowski spacetime. Despite previous claims in the literature, the validity of this inequality remains open. In this paper, we rewrite this inequality in terms of the geometry of the surface obtained by intersecting the past null cone of the original surface S with a constant time hyperplane and the 'time height' function of S over this hyperplane. We also specialize to the case when S lies in the past null cone of a point and show the validity of the corresponding inequality in any dimension (in four dimensions this inequality was proved by Tod (1985 Class. Quantum Grav. 2 L65-8). Exploiting properties of convex hypersurfaces in the Euclidean space, we write down the Penrose inequality in the Minkowski spacetime of an arbitrary dimension n + 2 as an inequality for two smooth functions on the sphere S n . We finally obtain a sufficient condition for the validity of the Penrose inequality in the four-dimensional Minkowski spacetime and show that this condition is satisfied by a large class of surfaces. (paper)
A robust null hypothesis for the potential causes of megadrought in western North America
Ault, T.; St George, S.; Smerdon, J. E.; Coats, S.; Mankin, J. S.; Cruz, C. C.; Cook, B.; Stevenson, S.
2017-12-01
The western United States was affected by several megadroughts during the last 1200 years, most prominently during the Medieval Climate Anomaly (MCA: 800 to 1300 CE). A null hypothesis is developed to test the possibility that, given a sufficiently long period of time, these events are inevitable and occur purely as a consequence of internal climate variability. The null distribution of this hypothesis is populated by a linear inverse model (LIM) constructed from global sea-surface temperature anomalies and self-calibrated Palmer Drought Severity Index data for North America. Despite being trained only on seasonal data from the late 20th century, the LIM produces megadroughts that are comparable in their duration, spatial scale, and magnitude as the most severe events of the last 12 centuries. The null hypothesis therefore cannot be rejected with much confidence when considering these features of megadrought, meaning that similar events are possible today, even without any changes to boundary conditions. In contrast, the observed clustering of megadroughts in the MCA, as well as the change in mean hydroclimate between the MCA and the 1500-2000 period, are more likely to have been caused by either external forcing or by internal climate variability not well sampled during the latter half of the Twentieth Century. Finally, the results demonstrate the LIM is a viable tool for determining whether paleoclimate reconstructions events should be ascribed to external forcings, "out of sample" climate mechanisms, or if they are consistent with the variability observed during the recent period.
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
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.
Percentiles of the null distribution of 2 maximum lod score tests.
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
La memoria social y la memoria política
Lifschitz, Javier Alejandro
2012-01-01
El artículo trata sobre la constitución del campo de la memoria política. Discute inicialmente la perspectiva de la memoria social y aborda, a partir de autores como Bourdieu y Habermas, la idea de un campo de la memoria política. Identifica dos momentos de inflexión en la constitución de ese campo. Un primer momento, en que la memoria política se inscribe en los procesos estatales de construcción de una memoria nacional y un segundo momento, que tiene como referencia principalmente el contex...
Arma del contrapoder: Humor político y medios
César Ulloa Tapia
2008-01-01
El humor político en los medios de comunicación tiene enorme acogida en las audiencias ya que logra lo que pueden editoriales, análisis académicos y demás espacios de opinión. Es la mejor manera de denunciar, advertir, sancionar e incluso develar lo que hace o deja de hacer el poder político. El humor político está considerado como contrapoder. El periodismo que usa el humor es eficaz, tanto en el mensaje como en su efecto, pues describe las situaciones y recurre a comparaciones y símiles....
Parkin protects dopaminergic neurons from excessive Wnt/{beta}-catenin signaling
Energy Technology Data Exchange (ETDEWEB)
Rawal, Nina [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden); Corti, Olga [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Sacchetti, Paola [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden); Ardilla-Osorio, Hector [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Sehat, Bita [Cancer Center Karolinska, Karolinska Institute, S-17177 Stockholm (Sweden); Brice, Alexis [Universite Pierre et Marie Curie-Paris 6, CRICM UMR-S975, Inserm, U975 (France); CNRS, UMR 7225, Paris (France); Department of Genetics and Cytogenetics, AP-HP, Groupe Hospitalier Pitie-Salpetriere, Paris (France); Arenas, Ernest, E-mail: Ernest.Arenas@ki.se [Laboratory of Molecular Neurobiology, MBB, DBRM, Karolinska Institute, S-17177 Stockholm (Sweden)
2009-10-23
Parkinson's disease (PD) is caused by degeneration of the dopaminergic (DA) neurons of the substantia nigra but the molecular mechanisms underlying the degenerative process remain elusive. Several reports suggest that cell cycle deregulation in post-mitotic neurons could lead to neuronal cell death. We now show that Parkin, an E3 ubiquitin ligase linked to familial PD, regulates {beta}-catenin protein levels in vivo. Stabilization of {beta}-catenin in differentiated primary ventral midbrain neurons results in increased levels of cyclin E and proliferation, followed by increased levels of cleaved PARP and loss of DA neurons. Wnt3a signaling also causes death of post-mitotic DA neurons in parkin null animals, suggesting that both increased stabilization and decreased degradation of {beta}-catenin results in DA cell death. These findings demonstrate a novel regulation of Wnt signaling by Parkin and suggest that Parkin protects DA neurons against excessive Wnt signaling and {beta}-catenin-induced cell death.
SQED two-loop beta function in the context of Implicit regularization
International Nuclear Information System (INIS)
Cherchiglia, Adriano Lana; Sampaio, Marcos; Nemes, Maria Carolina
2013-01-01
Full text: In this work we present the state-of-art for Implicit Regularization (IReg) in the context of supersymmetric theories. IReg is a four-dimensional regularization technique in momentum space which disentangles, in a consistent way at arbitrary order, the divergencies, regularization dependent and finite parts of any Feynman amplitude. Since it does not resort to modifications on the physical space-time dimensions of the underlying quantum field theoretical model, it can be consistently applied to supersymmetric theories. First we describe the technique and present previous results for supersymmetric models: the two-loop beta function for the Wess-Zumino model (both in the component and superfield formalism); the two-loop beta function for Super Yang-Mills (in the superfield formalism using the background field technique). After, we present our calculation of the two-loop beta function for massless and massive SQED using the superfield formalism with and without resorting to the background field technique. We find that only in the second case the two-loop divergence cancels out. We argue it is due to an anomalous Jacobian under the rescaling of the fields in the path-integral which is necessary for the application of the supersymmetric background field technique. We find, however, that in both cases the two-loop coefficients of beta function are non-null. Finally we briefly discuss the anomaly puzzle in the context of our technique. (author)
Tables of double beta decay data
Energy Technology Data Exchange (ETDEWEB)
Tretyak, V.I. [AN Ukrainskoj SSR, Kiev (Ukraine)]|[Strasbourg-1 Univ., 67 (France). Centre de Recherches Nucleaires; Zdesenko, Y.G. [AN Ukrainskoj SSR, Kiev (Ukraine)
1995-12-31
A compilation of experimental data on double beta decay is presented. The tables contain the most stringent known experimental limits or positive results of 2{beta} transitions of 69 natural nuclides to ground and excited states of daughter nuclei for different channels (2{beta}{sup -}; 2{beta}{sup +}; {epsilon}{beta}{sup +}; 2{epsilon}) and modes (0{nu}; 2{nu}; 0{nu}M) of decay. (authors). 189 refs., 9 figs., 3 tabs.
Beta Instability and Stochastic Market Weights
David H. Goldenberg
1985-01-01
An argument is given for individual firm beta instability based upon the stochastic character of the market weights defining the market portfolio and the constancy of its beta. This argument is generalized to market weighted portfolios and the form of the stochastic process generating betas is linked to that of the market return process. The implications of this analysis for adequacy of models of beta nonstationarity and estimation of betas are considered in light of the available empirical e...
Multi-Segment Radius Measurement Using an Absolute Distance Meter Through a Null Assembly
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
In-trap decay spectroscopy for {beta}{beta} decays
Energy Technology Data Exchange (ETDEWEB)
Brunner, Thomas
2011-01-18
The presented work describes the implementation of a new technique to measure electron-capture (EC) branching ratios (BRs) of intermediate nuclei in {beta}{beta} decays. This technique has been developed at TRIUMF in Vancouver, Canada. It facilitates one of TRIUMF's Ion Traps for Atomic and Nuclear science (TITAN), the Electron Beam Ion Trap (EBIT) that is used as a spectroscopy Penning trap. Radioactive ions, produced at the radioactive isotope facility ISAC, are injected and stored in the spectroscopy Penning trap while their decays are observed. A key feature of this technique is the use of a strong magnetic field, required for trapping. It radially confines electrons from {beta} decays along the trap axis while X-rays, following an EC, are emitted isotropically. This provides spatial separation of X-ray and {beta} detection with almost no {beta}-induced background at the X-ray detector, allowing weak EC branches to be measured. Furthermore, the combination of several traps allows one to isobarically clean the sample prior to the in-trap decay spectroscopy measurement. This technique has been developed to measure ECBRs of transition nuclei in {beta}{beta} decays. Detailed knowledge of these electron capture branches is crucial for a better understanding of the underlying nuclear physics in {beta}{beta} decays. These branches are typically of the order of 10{sup -5} and therefore difficult to measure. Conventional measurements suffer from isobaric contamination and a dominating {beta} background at theX-ray detector. Additionally, X-rays are attenuated by the material where the radioactive sample is implanted. To overcome these limitations, the technique of in-trap decay spectroscopy has been developed. In this work, the EBIT was connected to the TITAN beam line and has been commissioned. Using the developed beam diagnostics, ions were injected into the Penning trap and systematic studies on injection and storage optimization were performed. Furthermore, Ge
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.
DEFF Research Database (Denmark)
Ross-Hansen, Katrine; Menné, Torkil; Johansen, Jeanne D
2011-01-01
It was recently shown that filaggrin null mutation carrier status was associated with nickel allergy and self-reported intolerance to costume jewellery. Because of the biochemical characteristics of filaggrin, it may show nickel barrier properties in the stratum corneum....
Directory of Open Access Journals (Sweden)
Darío Salinas Figueredo
2000-01-01
Full Text Available Sin desconocer las aproximaciones existentes sobre aspectos fundamentales de la problemática social en América Latina, por ejemplo la pobreza y la índole de política que de manera predominante se formula para encararla, la trayectoria argumental de este trabajo se encamina a mostrar la importancia de trabajar hacia el desarrollo de una perspectiva más amplia. Las referencias empíricas cotejadas no se refieren a hechos puntuales, sino a indicadores que pautan tendencias. Siendo los propósitos aquí reunidos de naturaleza comprensiva, se parte de la premisa según la cual escasamente se problematiza lo social y la propia política social, sus vínculos con la política general, el modelo de desarrollo y el tipo de democracia que la política predominante busca proyectar.
International Nuclear Information System (INIS)
Deen, K.C.; Sweet, R.W.
1986-01-01
Sequences in the human genome with homology to the murine mammary tumor virus (MMTV) pol gene were isolated from a human phage library. Ten clones with extensive pol homology were shown to define five separate loci. These loci share common sequences immediately adjacent to the pol-like segments and, in addition, contain a related repeat element which bounds this region. This organization is suggestive of a proviral structure. The authors estimate that the human genome contains 30 to 40 copies of these pol-related sequences. The pol region of one of the cloned segments (HM16) and the complete MMTV pol gene were sequenced and compared. The nucleotide homology between these pol sequences is 52% and is concentrated in the terminal regions. The MMTV pol gene contains a single long open reading frame encoding 899 amino acids and is demarcated from the partially overlapping putative gag gene by termination codons and a shift in translational reading frame. The pol sequence of HM16 is multiply terminated but does contain open reading frames which encode 370, 105, and 112 amino acids residues in separate reading frames. The authors deduced a composite pol protein sequence for HM16 by aligning it to the MMTV pol gene and then compared these sequences with other retroviral pol protein sequences. Conserved sequences occur in both the amino and carboxyl regions which lie within the polymerase and endonuclease domains of pol, respectively
Directory of Open Access Journals (Sweden)
Manuel Briceño Jáuregui
1982-07-01
Full Text Available Se trata solamente de La Política, una versión reciente que está en proceso de publicación. Aristóteles sostiene que la felicidad completa del individuo no es posible sino en la sociedad, especialmente en la polis, que es la sociedad por excelencia. El individuo no puede por sí mismo satisfacer sus necesidad es materiales ni alcanzar la virtud. Para mostrarlo examina primero los diferentes grupos humanos, a partir de la familia; analiza luego las diversas politeias (constituciones de entonces, algunas de las cuales condena. Distingue siguiendo a su maestro Platón tres politeias (formas de gobierno legítimas monarquía, aristocracia, democracia, que dan lugar a su vez a tres desviaciones de las mismas tiranía , oligarquía y demagogia respectivamente. Termina señalando la importancia humana y cívica de la educación.
Directory of Open Access Journals (Sweden)
Isabel Lillo Villalobos
2011-04-01
Full Text Available En este trabajo se aplican conceptos matemáticos al planteamiento deun problema de competición política. Se desarrolla y se implementaademás un método que usa herramientas relacionadas con la geometríacomputacional para la resolución de dicho problema, probándose dicho método en un ejemplo basado en la política española.
Cultura política y partidos en Jalisco
Directory of Open Access Journals (Sweden)
Carlos Silva Moreno
2000-01-01
Full Text Available El presente trabajo es un intento de análisis y reflexión sobre la cultura política de uno de los componentes de todo sistema político que se precie de ser democrático (al menos formalmente: los partidos políticos. Se estudia la cultura política de los partidos políticos en Jalisco a partir del análisis de las representaciones y valores que los partidos políticos tienen sobre la democracia interna, para después contrastarlas con algunas prácticas referentes al liderazgo, dirección y formas de competencia. Debido a que las dimensiones de la democracia son muy amplias y variadas, nos centramos en dos indicadores: la forma en que se da la competencia por los cargos de dirección interna y el carácter de la dirección y el liderazgo.
Fluctuations of pol I and fibrillarin contents of the nucleoli.
Hornáček, M; Kováčik, L; Mazel, T; Cmarko, D; Bártová, E; Raška, I; Smirnov, E
2017-07-04
Nucleoli are formed on the basis of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). Each NOR contains multiple genes coding for RNAs of the ribosomal particles. The prominent components of the nucleolar ultrastructure, fibrillar centers (FC) and dense fibrillar components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene. In this work, we transfected human-derived cells with GFP-RPA43 (subunit of pol I) and RFP-fibrillarin. Following changes of the fluorescent signals in individual FC/DFC units, we found two kinds of kinetics: 1) the rapid fluctuations with periods of 2-3 min, when the pol I and fibrillarin signals oscillated in anti-phase manner, and the intensities of pol I in the neighboring FC/DFC units did not correlate. 2) fluctuations with periods of 10 to 60 min, in which pol I and fibrillarin signals measured in the same unit did not correlate, but pol I signals in the units belonging to different nucleoli were synchronized. Our data indicate that a complex pulsing activity of transcription as well as early processing is common for ribosomal genes.
Directory of Open Access Journals (Sweden)
Wesley C. Marshall
2011-01-01
Full Text Available El artículo busca resaltar la relevancia de la vida política de Hilferding en el actual contexto de la crisis financiera global y la probablemente alta radicalización de las posiciones políticas de los países dominantes como resultado de aquella. Como se argumenta, había un alto grado de coherencia entre el pensamiento económico de Hilferding y su actuación política. Justamente por el hecho de que el proyecto socialista alemán durante la Republica Weimar no logró sus objetivos, el pensamiento político y económico de su líder intelectual es altamente relevante en el escenario global actual, donde la crisis económica y descomposición social y política que la acompañen reclaman a los principales políticos del mundo un entendimiento económico más amplio y profundo para que las tragedias de Europa central de los años treinta y cuarenta del siglo XX no se reproduzcan.
Directory of Open Access Journals (Sweden)
Martínez de la Escalera, Ana María
2005-06-01
Full Text Available In this paper the act of lying is seen as a necessary component of the political discourse of the polis. Plato and Arendt are examined as the representatives of a line of thought in which the political realm needs the act of lying. The actual problematic of lying in politics is debated.
El texto «Mentir en política» aborda el papel que la mentira ha jugado en el lenguaje de la política y el lugar problemático que la Filosofía política le ha otorgado. Se escogen dos autores, Platón y Arendt, para mostrar la necesidad de incluir el discurso mentiroso como un componente esencial de la vida política de la ciudad. En breve, se trata de analizar los límites que la ciudad impone al discurso de lo político y de la política.
Mitochondrial DNA replication: a PrimPol perspective
Bailey, Laura J.
2017-01-01
PrimPol, (primase–polymerase), the most recently identified eukaryotic polymerase, has roles in both nuclear and mitochondrial DNA maintenance. PrimPol is capable of acting as a DNA polymerase, with the ability to extend primers and also bypass a variety of oxidative and photolesions. In addition, PrimPol also functions as a primase, catalysing the preferential formation of DNA primers in a zinc finger-dependent manner. Although PrimPol's catalytic activities have been uncovered in vitro, we still know little about how and why it is targeted to the mitochondrion and what its key roles are in the maintenance of this multicopy DNA molecule. Unlike nuclear DNA, the mammalian mitochondrial genome is circular and the organelle has many unique proteins essential for its maintenance, presenting a differing environment within which PrimPol must function. Here, we discuss what is currently known about the mechanisms of DNA replication in the mitochondrion, the proteins that carry out these processes and how PrimPol is likely to be involved in assisting this vital cellular process. PMID:28408491
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.
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.
DEFF Research Database (Denmark)
Winther, Kenneth Lillelund; Steenstrup, Søren Resen
2016-01-01
that smart beta investing probably will do better than passive market capitalization investing over time, we believe many are coming to a conclusion too quickly regarding active managers. Institutional investors are able to guide managers through benchmarks and risk frameworks toward the same well......Smart beta has become the flavor of the decade in the investment world with its low fees, easy access to rewarded risk premiums, and appearance of providing good investment results relative to both traditional passive benchmarks and actively managed funds. Although we consider it well documented......-documented smart beta risk premiums and still motivate active managers to avoid value traps, too highly priced small caps, defensives, etc. By constructing the equity portfolios of active managers that resemble the most widely used risk premiums, we show that the returns and risk-adjusted returns measures...
Qu, Qiuhao; Sun, Guoqiang; Li, Wenwu; Yang, Su; Ye, Peng; Zhao, Chunnian; Yu, Ruth T; Gage, Fred H; Evans, Ronald M; Shi, Yanhong
2010-01-01
The nuclear receptor TLX (also known as NR2E1) is essential for adult neural stem cell self-renewal; however, the molecular mechanisms involved remain elusive. Here we show that TLX activates the canonical Wnt/beta-catenin pathway in adult mouse neural stem cells. Furthermore, we demonstrate that Wnt/beta-catenin signalling is important in the proliferation and self-renewal of adult neural stem cells in the presence of epidermal growth factor and fibroblast growth factor. Wnt7a and active beta-catenin promote neural stem cell self-renewal, whereas the deletion of Wnt7a or the lentiviral transduction of axin, a beta-catenin inhibitor, led to decreased cell proliferation in adult neurogenic areas. Lentiviral transduction of active beta-catenin led to increased numbers of type B neural stem cells in the subventricular zone of adult brains, whereas deletion of Wnt7a or TLX resulted in decreased numbers of neural stem cells retaining bromodeoxyuridine label in the adult brain. Both Wnt7a and active beta-catenin significantly rescued a TLX (also known as Nr2e1) short interfering RNA-induced deficiency in neural stem cell proliferation. Lentiviral transduction of an active beta-catenin increased cell proliferation in neurogenic areas of TLX-null adult brains markedly. These results strongly support the hypothesis that TLX acts through the Wnt/beta-catenin pathway to regulate neural stem cell proliferation and self-renewal. Moreover, this study suggests that neural stem cells can promote their own self-renewal by secreting signalling molecules that act in an autocrine/paracrine mode.
International Nuclear Information System (INIS)
Hubert, F.; Dufour, J.P.; Moral, R. del; Fleury, A.; Jean, D.; Pravikoff, M.S.; Delagrange, H.; Geissel, H.; Schmidt, K.H.; Hanelt, E.
1989-01-01
The beta-gamma spectroscopic study of 22 O is presented. This nucleus, produced as a projectile-like fragment from the interaction of a 60 MeV/n 40 Ar beam with a Be target, has been separated by the LISE spectrometer. Several gamma rays from 22 O decay have been observed, from which a half-life of (2.25±0.15) s has been determined. Accurate excitation energies have been deduced for several states in 22 F. A partial beta decay scheme of 22 O has been established. Experimental results have been compared with shell model calculations. (orig.)
Beta-hemolytic Streptococcal Bacteremia
DEFF Research Database (Denmark)
Nielsen, Hans Ulrik; Kolmos, Hans Jørn; Frimodt-Møller, Niels
2002-01-01
Bacteremia with beta-hemolytic Streptococci groups A, B, C and G has a mortality rate of approximately 20%. In this study we analyzed the association of various patient risk factors with mortality. Records from 241 patients with beta-hemolytic streptococcal bacteremia were reviewed with particular...... attention to which predisposing factors were predictors of death. A logistic regression model found age, burns, immunosuppressive treatment and iatrogenic procedures prior to the infection to be significant predictors of death, with odds ratios of 1.7 (per decade), 19.7, 3.6 and 6.8, respectively...
The Beta Transmuted Weibull Distribution
Directory of Open Access Journals (Sweden)
Manisha Pal
2014-06-01
Full Text Available The paper introduces a beta transmuted Weibull distribution, which contains a number ofdistributions as special cases. The properties of the distribution are discussed and explicit expressions are derived for the mean deviations, Bonferroni and Lorenz curves, and reliability. The distribution and moments of order statistics are also studied. Estimation of the model parameters by the method of maximum likelihood is discussed. The log beta transmuted Weibull model is introduced to analyze censored data. Finally, the usefulness of the new distribution in analyzing positive data is illustrated.
Beta activity of enriched uranium
International Nuclear Information System (INIS)
Nambiar, P.P.V.J.; Ramachandran, V.
1975-01-01
Use of enriched uranium as reactor fuel necessitates its handling in various forms. For purposes of planning and organising radiation protection measures in enriched uranium handling facilities, it is necessary to have a basic knowledge of the radiation status of enriched uranium systems. The theoretical variations in beta activity and energy with U 235 enrichment are presented. Depletion is considered separately. Beta activity build up is also studied for two specific enrichments, in respect of which experimental values for specific alpha activity are available. (author)
Numerical simulations of sheared magnetic lines at the solar null line
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
Directory of Open Access Journals (Sweden)
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
A {beta} - {gamma} coincidence; Metodo de coincidencias {beta} - {gamma}
Energy Technology Data Exchange (ETDEWEB)
Agullo, F
1960-07-01
A {beta} - {gamma} coincidence method for absolute counting is given. The fundamental principles are revised and the experimental part is detailed. The results from {sup 1}98 Au irradiated in the JEN 1 Swimming pool reactor are given. The maximal accuracy is 1 per cent. (Author) 11 refs.
Null hypothesis significance tests. A mix-up of two different theories
DEFF Research Database (Denmark)
Schneider, Jesper Wiborg
2015-01-01
criticisms raised against NHST. As practiced, NHST has been characterized as a ‘null ritual’ that is overused and too often misapplied and misinterpreted. NHST is in fact a patchwork of two fundamentally different classical statistical testing models, often blended with some wishful quasi......-Bayesian interpretations. This is undoubtedly a major reason why NHST is very often misunderstood. But NHST also has intrinsic logical problems and the epistemic range of the information provided by such tests is much more limited than most researchers recognize. In this article we introduce to the scientometric community...
Topology and Singularities in Cosmological Spacetimes Obeying the Null Energy Condition
Galloway, Gregory J.; Ling, Eric
2018-06-01
We consider globally hyperbolic spacetimes with compact Cauchy surfaces in a setting compatible with the presence of a positive cosmological constant. More specifically, for 3 + 1 dimensional spacetimes which satisfy the null energy condition and contain a future expanding compact Cauchy surface, we establish a precise connection between the topology of the Cauchy surfaces and the occurrence of past singularities. In addition to the Penrose singularity theorem, the proof makes use of some recent advances in the topology of 3-manifolds and of certain fundamental existence results for minimal surfaces.
Null geodesics in black hole metrics with non-zero cosmological constant
International Nuclear Information System (INIS)
Stuchlik, Z.; Calvani, M.
1990-02-01
We study the radial motion along null geodesics in the Reissner-Nordstroem-de Sitter and Kerr-de Sitter space-times. We analyze the properties of the effective potential and we discuss circular orbits. We find that the radii of circular geodesics in the Reissner-Nordstroem-de Sitter space-time do not depend on the cosmological constant, and we explain this property using the optical reference geometry. In addition, we describe the unusual consequences of the interplay between rotation of the source and cosmological repulsion. (author). 16 refs, 8 figs
Reply to "Comment on `Null weak values and the past of a quantum particle"'
Duprey, Q.; Matzkin, A.
2018-04-01
We discuss the preceding Comment [D. Sokolovski, preceding Comment, Phys. Rev. A 97, 046102 (2018), 10.1103/PhysRevA.97.046102] and conclude that the arguments given there against the relevance of null weak values as representing the absence of a system property are not compelling. We give an example in which the transition matrix elements that make the projector weak values vanish are the same ones that suppress detector clicks in strong measurements. Whether weak values are taken to account for the past of a quantum system or not depend on general interpretational commitments of the quantum formalism itself rather than on peculiarities of the weak measurements framework.
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
The space-time outside a source of gravitational radiation: the axially symmetric null fluid
Energy Technology Data Exchange (ETDEWEB)
Herrera, L. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Universidad de Salamanca, Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain); Di Prisco, A. [Universidad Central de Venezuela, Escuela de Fisica, Facultad de Ciencias, Caracas (Venezuela, Bolivarian Republic of); Ospino, J. [Universidad de Salamanca, Departamento de Matematica Aplicada and Instituto Universitario de Fisica Fundamental y Matematicas, Salamanca (Spain)
2016-11-15
We carry out a study of the exterior of an axially and reflection symmetric source of gravitational radiation. The exterior of such a source is filled with a null fluid produced by the dissipative processes inherent to the emission of gravitational radiation, thereby representing a generalization of the Vaidya metric for axially and reflection symmetric space-times. The role of the vorticity, and its relationship with the presence of gravitational radiation is put in evidence. The spherically symmetric case (Vaidya) is, asymptotically, recovered within the context of the 1 + 3 formalism. (orig.)
Schindler, Michael
2017-08-02
The classification of effects caused by mixtures of agents as synergistic, antagonistic or additive depends critically on the reference model of 'null interaction'. Two main approaches are currently in use, the Additive Dose (ADM) or concentration addition (CA) and the Multiplicative Survival (MSM) or independent action (IA) models. We compare several response surface models to a newly developed Hill response surface, obtained by solving a logistic partial differential equation (PDE). Assuming that a mixture of chemicals with individual Hill-type dose-response curves can be described by an n-dimensional logistic function, Hill's differential equation for pure agents is replaced by a PDE for mixtures whose solution provides Hill surfaces as 'null-interaction' models and relies neither on Bliss independence or Loewe additivity nor uses Chou's unified general theory. An n-dimensional logistic PDE decribing the Hill-type response of n-component mixtures is solved. Appropriate boundary conditions ensure the correct asymptotic behaviour. Mathematica 11 (Wolfram, Mathematica Version 11.0, 2016) is used for the mathematics and graphics presented in this article. The Hill response surface ansatz can be applied to mixtures of compounds with arbitrary Hill parameters. Restrictions which are required when deriving analytical expressions for response surfaces from other principles, are unnecessary. Many approaches based on Loewe additivity turn out be special cases of the Hill approach whose increased flexibility permits a better description of 'null-effect' responses. Missing sham-compliance of Bliss IA, known as Colby's model in agrochemistry, leads to incompatibility with the Hill surface ansatz. Examples of binary and ternary mixtures illustrate the differences between the approaches. For Hill-slopes close to one and doses below the half-maximum effect doses MSM (Colby, Bliss, Finney, Abbott) predicts synergistic effects where the Hill model indicates 'null
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.
The 10-D chiral null model and the relation to 4-D string solutions
International Nuclear Information System (INIS)
Behrndt, K.
1994-12-01
The chiral null model is a generalization of the fundamental string and gravitational wave background. It is an example of a conformally invariant model in all orders in α' and has unbroken supersymmetries. In a Kaluza-Klein approach we start in 10 dimensions and reduce the model down to 4 dimensions without making any restrictions. The 4-D field content is given by the metric, torsion, dilaton, a moduli field and 6 gauge fields. This model is self-dual and near the singularities asymptotically free. The relation to known IWP, Taub-NUT and rotating black hole solutions is discussed. (orig.)
DEFF Research Database (Denmark)
Jones, Allan; Sommerlund, Bo
2007-01-01
The uses of null hypothesis significance testing (NHST) and statistical power analysis within psychological research are critically discussed. The article looks at the problems of relying solely on NHST when dealing with small and large sample sizes. The use of power-analysis in estimating...... the potential error introduced by small and large samples is advocated. Power analysis is not recommended as a replacement to NHST but as an additional source of information about the phenomena under investigation. Moreover, the importance of conceptual analysis in relation to statistical analysis of hypothesis...
Asymptotically shear-free and twist-free null geodesic congruences
International Nuclear Information System (INIS)
Kozameh, Carlos; Newman, Ezra T
2007-01-01
The Robinson-Trautman spacetime is a special case of asymptotically flat spacetimes that possess asymptotically shear-free and twist-free (surface forming) null geodesic congruences. In this paper we show that, although they are rare, a larger class of asymptotically flat spacetimes with this property does exist. In particular, we display the class of spacetimes that possess this dual property and demonstrate how these congruences can be found. In addition, we show that in each case the congruence is isolated in the sense that there are no other neighbouring congruences with this dual property
High-contrast visible nulling coronagraph for segmented and arbitrary telescope apertures
Hicks, Brian A.; Lyon, Richard G.; Bolcar, Matthew R.; Clampin, Mark; Petrone, Peter
2014-08-01
Exoplanet coronagraphy will be driven by the telescope architectures available and thus the system designer must have available one or more suitable coronagraphic instrument choices that spans the set of telescope apertures, including filled (off-axis), obscured (e.g. with secondary mirror spiders and struts), segmented apertures, such as JWST, and interferometric apertures. In this work we present one such choice of coronagraph, known as the visible nulling coronagraph (VNC), that spans all four types of aperture and also employs differential sensing and control.
Testing the null hypothesis of the nonexistence of a preseizure state
International Nuclear Information System (INIS)
Andrzejak, Ralph G.; Kraskov, Alexander; Mormann, Florian; Rieke, Christoph; Kreuz, Thomas; Elger, Christian E.; Lehnertz, Klaus
2003-01-01
A rapidly growing number of studies deals with the prediction of epileptic seizures. For this purpose, various techniques derived from linear and nonlinear time series analysis have been applied to the electroencephalogram of epilepsy patients. In none of these works, however, the performance of the seizure prediction statistics is tested against a null hypothesis, an otherwise ubiquitous concept in science. In consequence, the evaluation of the reported performance values is problematic. Here, we propose the technique of seizure time surrogates based on a Monte Carlo simulation to remedy this deficit
Testing the null hypothesis of the nonexistence of a preseizure state
Energy Technology Data Exchange (ETDEWEB)
Andrzejak, Ralph G; Kraskov, Alexander [John-von-Neumann Institute for Computing, Forschungszentrum Juelich, 52425 Juelich (Germany); Mormann, Florian; Rieke, Christoph [Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn (Germany); Helmholtz Institut fuer Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, 53115 Bonn (Germany); Kreuz, Thomas [John-von-Neumann Institute for Computing, Forschungszentrum Juelich, 52425 Juelich (Germany); Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn (Germany); Elger, Christian E; Lehnertz, Klaus [Department of Epileptology, University of Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn (Germany)
2003-01-01
A rapidly growing number of studies deals with the prediction of epileptic seizures. For this purpose, various techniques derived from linear and nonlinear time series analysis have been applied to the electroencephalogram of epilepsy patients. In none of these works, however, the performance of the seizure prediction statistics is tested against a null hypothesis, an otherwise ubiquitous concept in science. In consequence, the evaluation of the reported performance values is problematic. Here, we propose the technique of seizure time surrogates based on a Monte Carlo simulation to remedy this deficit.
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.
Five-dimensional null-cone structure of big bang singularity
International Nuclear Information System (INIS)
Lauro, S.; Schucking, E.L.
1985-01-01
The Friedmann model PHI of positive space curvature, vanishing pressure and cosmological constant when isometrically imbedded as a hypersurface in five-dimensional Minkowski space M 5 is globally rigid: if F(PHI) and F'(PHI) are isometric embeddings in M 5 there is a motion π of M 5 such that F'=π 0 F. The big bang singularity is the vertex of a null half-cone in M 5 . Global rigidity leads to an invariant characterization of the singularity. The structure of matter at the singularity is governed by the de Sitter group. (author)
Five-dimensional null-cone structure of big bang singularity
Energy Technology Data Exchange (ETDEWEB)
Lauro, S.; Schucking, E.L.
1985-04-01
The Friedmann model PHI of positive space curvature, vanishing pressure and cosmological constant when isometrically imbedded as a hypersurface in five-dimensional Minkowski space MV is globally rigid: if F(PHI) and F'(PHI) are isometric embeddings in MV there is a motion of MV such that F'= F. The big bang singularity is the vertex of a null half-cone in MV. Global rigidity leads to an invariant characterization of the singularity. The structure of matter at the singularity is governed by the de Sitter group.
Dimension shifting operators and null states in 2D conformally invariant field theories
International Nuclear Information System (INIS)
Gervais, J.L.
1986-01-01
We discuss the existence and properties of differential operators which transform covariant operators into covariant operators of different weights in two-dimensional conformally invariant field theories. We relate them to null states and the vanishing of the Kac determinant in representations of the conformal algebra, and to the existence of differential equations for Green functions of covariant operators. In this framework, we rederive the essential features of our earlier work on dual models with shifted intercept, which in euclidean space-time gives explicit solutions of the conformal bootstrap equations where all operators are marginal. (orig.)
Sibi; Liu
2000-10-19
Chiral Lewis acid catalyzed N-benzylhydroxylamine addition to pyrrolidinone-derived enoates afforded beta-aryl-beta-amino acid derivatives in high enantiomeric purity with moderate to very good chemical efficiency.
Raymond Aron ante el maquiavelismo político
Directory of Open Access Journals (Sweden)
Molina Cano, Jerónimo
2008-08-01
Full Text Available It is a simplification of Raymond Aron´s thought to consider him as a mere neo-liberal political thinker. The French sociologist, a well-known political realist, took part in the famous controversy about Machiavellianism that was Aron´s intellectual watershed from the Forties. Starting from that controversy the aim of the present paper is to inquire into his contribution to the so-called “moderate Machiavellianism”, whose Arcanum is that it is not always possible to choose the optimal means to face the right political action. Machiavellianism is not a merely scientific or epistemological question, but something that deeply determines all political actions.
La presentación de Raymond Aron como un escritor político neoliberal constituye una simplificación de su pensamiento. El sociólogo francés, que pertenece a la tradición del realismo político, tuvo una destacada intervención en la famosa polémica sobre el maquiavelismo que marcó un punto de inflexión en su pensamiento. Este artículo examina su contribución a esa inagotable polémica intelectual desde los años 40 y constata, finalmente, su encuadramiento en el denominado “maquiavelismo moderado”, cuyo arcano político es que, en política, no siempre se pueden elegir los medios de la acción. El maquiavelismo no es, en este sentido, un asunto científico o epistemológico, sino que determina profundamente toda acción política.
Electret dosemeter for beta radiation
International Nuclear Information System (INIS)
Campos, L.L.; Caldas, L.V.E.; Mascarenhas, S.
The response characteristics of an electret dosemeter for beta radiation are studied. Experiments were performed using different geometries and walls, and it was verified for which geometry the dosemeter sensitivity is greater. Sources of 90 Sr - 90 Y, 204 Tl and 85 Kr were used in the experiments. (I.C.R.) [pt
Personnel monitoring for beta rays
International Nuclear Information System (INIS)
Piesch, E.; Johns, T.F.
1983-01-01
The practical considerations which have to be taken into account in the design of personnel monitors intended to measure doses resulting from exposure to beta rays are discussed. These include the measurement of doses in situations involving either fairly uniform or non-uniform irradiation and of doses to the male gonads. (UK)
Constraining neutrinoless double beta decay
International Nuclear Information System (INIS)
Dorame, L.; Meloni, D.; Morisi, S.; Peinado, E.; Valle, J.W.F.
2012-01-01
A class of discrete flavor-symmetry-based models predicts constrained neutrino mass matrix schemes that lead to specific neutrino mass sum-rules (MSR). We show how these theories may constrain the absolute scale of neutrino mass, leading in most of the cases to a lower bound on the neutrinoless double beta decay effective amplitude.
DEFF Research Database (Denmark)
Heller, R Scott; Madsen, Ole D; Nielsen, Jens Høiriis
2013-01-01
The very modern Kyoto International Conference Center provided the site for the 8th workshop on Beta cells on April 23-26, 2013. The preceding workshops were held in Boston, USA (1991); Kyoto, Japan (1994); Helsingør, Denmark (1997); Helsinki, Finland (2003); El Perello, Spain (2006); Peebles...
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
Beta calibration and dosimetry at IPEN
International Nuclear Information System (INIS)
Caldas, L.V.E.
1983-01-01
A commercial extrapolation chamber (PTW, Germany) was tested in different beta radiation fields and its properties investigated. Its usefullness for beta radiation calibration and dosimetry was demonstrated. (Author) [pt
Xu, Chunxiao; Yin, Xiao; Lv, Yan; Wu, Changzhe; Zhang, Yuxia; Song, Tao
2012-03-01
The blue light receptor, cryptochrome, has been suggested to act as a magnetoreceptor based on the proposition that photochemical reactions are involved in sensing the geomagnetic field. But the effects of the geomagnetic field on cryptochrome remain unclear. Although the functions of cryptochrome have been well demonstrated for Arabidopsis, the effect of the geomagnetic field on the growth of Arabidopsis and its mechanism of action are poorly understood. We eliminated the local geomagnetic field to grow Arabidopsis in a near-null magnetic field and found that the inhibition of Arabidopsis hypocotyl growth by white light was weakened, and flowering time was delayed. The expressions of three cryptochrome-signaling-related genes, PHYB, CO and FT also changed; the transcript level of PHYB was elevated ca. 40%, and that of CO and FT was reduced ca. 40% and 50%, respectively. These data suggest that the effects of a near-null magnetic field on Arabidopsis are cryptochrome-related, which may be revealed by a modification of the active state of cryptochrome and the subsequent signaling cascade.
Biological and genetic properties of the p53 null preneoplastic mammary epithelium
Medina, Daniel; Kittrell, Frances S.; Shepard, Anne; Stephens, L. Clifton; Jiang, Cheng; Lu, Junxuan; Allred, D. Craig; McCarthy, Maureen; Ullrich, Robert L.
2002-01-01
The absence of the tumor suppressor gene p53 confers an increased tumorigenic risk for mammary epithelial cells. In this report, we describe the biological and genetic properties of the p53 null preneoplastic mouse mammary epithelium in a p53 wild-type environment. Mammary epithelium from p53 null mice was transplanted serially into the cleared mammary fat pads of p53 wild-type BALB/c female to develop stable outgrowth lines. The outgrowth lines were transplanted for 10 generations. The outgrowths were ductal in morphology and progressed through ductal hyperplasia and ductal carcinoma in situ before invasive cancer. The preneoplastic outgrowth lines were immortal and exhibited activated telomerase activity. They are estrogen and progesterone receptor-positive, and aneuploid, and had various levels of tumorigenic potential. The biological and genetic properties of these lines are distinct from those found in most hyperplastic alveolar outgrowth lines, the form of mammary preneoplasia occurring in most traditional models of murine mammary tumorigenesis. These results indicate that the preneoplastic cell populations found in this genetically engineered model are similar in biological properties to a subset of precurser lesions found in human breast cancer and provide a unique model to identify secondary events critical for tumorigenicity and invasiveness.
Telescopes in Near Space: Balloon Exoplanet Nulling Interferometer (BigBENI)
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.
International Nuclear Information System (INIS)
Tian Weiming; Kyriakides, Themis R
2009-01-01
Thrombospondin (TSP)-2 is a matricellular protein that participates in the processes of tissue repair and the foreign body response. In addition, TSP2 has been shown to influence synaptogenesis and recovery of the brain following stroke. In the present study we investigated the response following the implantation of polyvinyl alcohol (PVA) sponges in the brain. PVA sponges were implanted into the brain cortex of wild type and TSP2-null mice for a period of 4 and 8 weeks and the response was analyzed by histochemistry and quantitative immunohistochemistry. TSP2 expression was detected in the interstices of the sponge and co-localized with the extracellular matrix and astrocytes. PVA sponge invasion in TSP2-null mice was characterized by dense deposition of extracellular matrix and increased invasion of reactive astrocytes and macrophages/microglia. Furthermore, the angiogenic response was elevated and the detection of mouse serum albumin (MSA) in the brain cortex indicated excessive vessel leakage, suggesting that TSP2 plays a role in the repair/maintenance of the blood brain barrier. Finally, immunostaining demonstrated an increase in the levels of matrix metalloproteinase (MMP)-2 and MMP-9. Taken together, our observations support a role for TSP2 as critical determinant of the brain response to biomaterials.
Optimized scheduling technique of null subcarriers for peak power control in 3GPP LTE downlink.
Cho, Soobum; Park, Sang Kyu
2014-01-01
Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.
The gravitational exclusion principle and null states in anti-de Sitter space
International Nuclear Information System (INIS)
Castro, Alejandra; Maloney, Alexander; Hartman, Thomas
2011-01-01
The holographic principle implies a vast reduction in the number of degrees of freedom of quantum gravity. This idea can be made precise in AdS 3 , where the the stringy or gravitational exclusion principle asserts that certain perturbative excitations are not present in the exact quantum spectrum. We show that this effect is visible directly in the bulk gravity theory: the norm of the offending linearized state is zero or negative. When the norm is negative, the theory is signalling its own breakdown as an effective field theory; this provides a perturbative bulk explanation for the stringy exclusion principle. When the norm vanishes the bulk state is null rather than physical. This implies that certain non-trivial diffeomorphisms must be regarded as gauge symmetries rather than spectrum-generating elements of the asymptotic symmetry group. This leads to subtle effects in the computation of one-loop determinants for Einstein gravity, higher spin theories and topologically massive gravity in AdS 3 . In particular, heat kernel methods do not capture the correct spectrum of a theory with null states. Communicated by S Ross
Modular Hamiltonians for deformed half-spaces and the averaged null energy condition
Faulkner, Thomas; Leigh, Robert G.; Parrikar, Onkar; Wang, Huajia
2016-09-01
We study modular Hamiltonians corresponding to the vacuum state for deformed half-spaces in relativistic quantum field theories on {{R}}^{1,d-1} . We show that in addition to the usual boost generator, there is a contribution to the modular Hamiltonian at first order in the shape deformation, proportional to the integral of the null components of the stress tensor along the Rindler horizon. We use this fact along with monotonicity of relative entropy to prove the averaged null energy condition in Minkowski space-time. This subsequently gives a new proof of the Hofman-Maldacena bounds on the parameters appearing in CFT three-point functions. Our main technical advance involves adapting newly developed perturbative methods for calculating entanglement entropy to the problem at hand. These methods were recently used to prove certain results on the shape dependence of entanglement in CFTs and here we generalize these results to excited states and real time dynamics. We also discuss the AdS/CFT counterpart of this result, making connection with the recently proposed gravitational dual for modular Hamiltonians in holographic theories.
OEDGE modeling of the DIII-D double null (CH4)-C-13 puffing experiment
International Nuclear Information System (INIS)
Elder, J.D.; Wampler, W.R.; McLean, A.G.; Stangeby, P.C.; Allen, S.L.; Bray, B.D.; Brooks, N.H.; Leonard, A.W.; Unterberg, Ezekial A.; Watkins, J.G.
2011-01-01
Unbalanced double null ELMy H-mode configurations in DIII-D are used to simulate the situation in ITER high triangularity, burning plasma magnetic equilibria, where the second X-point lies close to the top of the vacuum vessel, creating a secondary divertor region at the upper blanket modules. The measured plasma conditions in the outer secondary divertor closely duplicated those projected for ITER. (CH4)-C-13 was injected into the secondary outer divertor to simulate sputtering there. The majority of the C-13 found was in the secondary outer divertor. This material migration pattern is radically different than that observed for main wall (CH4)-C-13 injections into single null configurations where the deposition is primarily at the inner divertor. The implications for tritium codeposition resulting from sputtering at the secondary divertor in ITER are significant since release of tritium from Be co-deposits at the main wall bake temperature for ITER, 240 degrees C, is incomplete. The principal features of the measured C-13 deposition pattern have been replicated by the OEDGE interpretive code.
Barillot, M.; Barthelemy, E.; Bastard, L.; Broquin, J.-E.; Hawkins, G.; Kirschner, V.; Ménard, S.; Parent, G.; Poinsot, C.; Pradel, A.; Vigreux, C.; Zhang, S.; Zhang, X.
2017-11-01
The search for Earth-like exoplanets, orbiting in the habitable zone of stars other than our Sun and showing biological activity, is one of the most exciting and challenging quests of the present time. Nulling interferometry from space, in the thermal infrared, appears as a promising candidate technique for the task of directly observing extra-solar planets. It has been studied for about 10 years by ESA and NASA in the framework of the Darwin and TPF-I missions respectively [1]. Nevertheless, nulling interferometry in the thermal infrared remains a technological challenge at several levels. Among them, the development of the "modal filter" function is mandatory for the filtering of the wavefronts in adequacy with the objective of rejecting the central star flux to an efficiency of about 105. Modal filtering [2] takes benefit of the capability of single-mode waveguides to transmit a single amplitude function, to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible. The modal filter may either be based on single-mode Integrated Optics (IO) and/or Fiber Optics. In this paper, we focus on IO, and more specifically on the progress of the on-going "Integrated Optics" activity of the European Space Agency.
Cdk2-Null Mice Are Resistant to ErbB-2-Induced Mammary Tumorigenesis
Directory of Open Access Journals (Sweden)
Dipankar Ray
2011-05-01
Full Text Available The concept of targeting G1 cyclin-dependent kinases (CDKs in breast cancer treatments is supported by the fact that the genetic ablation of Cdk4 had minimal impacts on normal cell proliferation in majority of cell types, resulting in near-normal mouse development, whereas such loss of Cdk4 completely abrogated ErbB-2/neu-induced mammary tumorigenesis in mice. In most human breast cancer tissues, another G1-regulatory CDK, CDK2, is also hyperactivated by various mechanisms and is believed to be an important therapeutic target. In this report, we provide genetic evidence that CDK2 is essential for proliferation and oncogenesis of murine mammary epithelial cells. We observed that 87% of Cdk2-null mice were protected from ErbB-2-induced mammary tumorigenesis. Mouse embryonic fibroblasts isolated from Cdk2-null mouse showed resistance to various oncogene-induced transformation. Previously, we have reported that hemizygous loss of Cdc25A, the major activator of CDK2, can also protect mice from ErbB-2-induced mammary tumorigenesis [Cancer Res (2007 67(14: 6605–11]. Thus, we propose that CDC25A-CDK2 pathway is critical for the oncogenic action of ErbB-2 in mammary epithelial cells, in a manner similar to Cyclin D1/CDK4 pathway.
Novel Remarks on Point Mass Sources, Firewalls, Null Singularities and Gravitational Entropy
Perelman, Carlos Castro
2016-01-01
A continuous family of static spherically symmetric solutions of Einstein's vacuum field equations with a spatial singularity at the origin r = 0 is found. These solutions are parametrized by a real valued parameter λ (ranging from 0 to 1) and such that the radial horizon's location is displaced continuously towards the singularity ( r = 0 ) as λ increases. In the extreme limit λ = 1, the location of the singularity and horizon merges leading to a null singularity. In this extreme case, any infalling observer hits the null singularity at the very moment he/she crosses the horizon. This fact may have important consequences for the resolution of the fire wall problem and the complementarity controversy in black holes. An heuristic argument is provided how one might avoid the Hawking particle emission process in this extreme case when the singularity and horizon merges. The field equations due to a delta-function point-mass source at r = 0 are solved and the Euclidean gravitational action corresponding to those solutions is evaluated explicitly. It is found that the Euclidean action is precisely equal to the black hole entropy (in Planck area units). This result holds in any dimensions D ≥ 3.
NULLING DATA REDUCTION AND ON-SKY PERFORMANCE OF THE LARGE BINOCULAR TELESCOPE INTERFEROMETER
Energy Technology Data Exchange (ETDEWEB)
Defrère, D.; Hinz, P. M.; Hoffmann, W. F.; Skemer, A. J.; Bailey, V.; Downey, E. C.; Durney, O.; Grenz, P.; McMahon, T. J.; Montoya, M.; Spalding, E.; Vaz, A.; Arbo, P.; Brusa, G. [Steward Observatory, Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Mennesson, B. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States); Millan-Gabet, R. [NASA Exoplanet Science Institute, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Danchi, W. C. [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Code 667, Greenbelt, MD 20771 (United States); Hill, J. M. [Large Binocular Telescope Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Absil, O. [Institut d’Astrophysique et de Géophysique, Université de Liège, 19c Allée du Six Août, B-4000 Sart Tilman (Belgium); Bailey, H., E-mail: ddefrere@email.arizona.edu [Lunar and Planetary Laboratory, University of Arizona, 1541 E, University Boulevard, Tucson, AZ 85721 (United States); and others
2016-06-20
The Large Binocular Telescope Interferometer (LBTI) is a versatile instrument designed for high angular resolution and high-contrast infrared imaging (1.5–13 μ m). In this paper, we focus on the mid-infrared (8–13 μ m) nulling mode and present its theory of operation, data reduction, and on-sky performance as of the end of the commissioning phase in 2015 March. With an interferometric baseline of 14.4 m, the LBTI nuller is specifically tuned to resolve the habitable zone of nearby main-sequence stars, where warm exozodiacal dust emission peaks. Measuring the exozodi luminosity function of nearby main-sequence stars is a key milestone to prepare for future exo-Earth direct imaging instruments. Thanks to recent progress in wavefront control and phase stabilization, as well as in data reduction techniques, the LBTI demonstrated in 2015 February a calibrated null accuracy of 0.05% over a 3 hr long observing sequence on the bright nearby A3V star β Leo. This is equivalent to an exozodiacal disk density of 15–30 zodi for a Sun-like star located at 10 pc, depending on the adopted disk model. This result sets a new record for high-contrast mid-infrared interferometric imaging and opens a new window on the study of planetary systems.
Wildeman, Christopher; Turney, Kristin
2014-06-01
We use data from the Fragile Families and Child Wellbeing Study to consider the effects of maternal incarceration on 21 caregiver- and teacher-reported behavioral problems among 9-year-old children. The results suggest three primary conclusions. First, children of incarcerated mothers are a disadvantaged group that exhibit high levels of caregiver- and teacher-reported behavioral problems. Second, after we adjust for selection, the effects of maternal incarceration on children's behavioral problems are consistently null (for 19 of 21 outcomes) and rarely positive (1 of 21) or negative (1 of 21), suggesting that the poor outcomes of these children are driven by disadvantages preceding maternal incarceration rather than incarceration. These effects, however, vary across race/ethnicity, with maternal incarceration diminishing caregiver-reported behavioral problems among non-Hispanic whites. Finally, in models considering both maternal and paternal incarceration, paternal incarceration is associated with more behavioral problems, which is consistent with previous research and suggests that the null effects of maternal incarceration are not artifacts of our sample or analytic decisions.
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)
Approaches for achieving broadband achromatic phase shifts for visible nulling coronagraphy
Bolcar, Matthew R.; Lyon, Richard G.
2012-07-01
Visible nulling coronagraphy is one of the few approaches to the direct detection and characterization of Jovian and Terrestrial exoplanets that works with segmented aperture telescopes. Jovian and Terrestrial planets require at least 10-9 and 10-10 image plane contrasts, respectively, within the spectral bandpass and thus require a nearly achromatic π-phase difference between the arms of the interferometer. An achromatic π-phase shift can be achieved by several techniques, including sequential angled thick glass plates of varying dispersive materials, distributed thin-film multilayer coatings, or techniques that leverage the polarization-dependent phase shift of total-internal reflections. Herein we describe two implementations of such techniques: sequential thick glass plates and Fresnel rhomb prisms. A viable technique must achieve the achromatic phase shift while simultaneously minimizing the intensity difference, chromatic beam spread and polarization variation between the interferometer arms. In this paper we describe the above implementations and report on the trades associated with each technique that will lead to an implementation of the most promising one in Goddard's Visible Nulling Coronagraph (VNC).
Identifying the null subject: evidence from event-related brain potentials.
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.
Catastrophe in the stochastic layer due to dipole perturbation for a single-null divertor Tokamak
International Nuclear Information System (INIS)
Ali, H.; Watson, M.; Punjabi, A.; Boozer, A.
1996-01-01
We use the method of maps developed by Punjabi and Boozer to investigate the motion of magnetic field lines in stochastic scrape-off layer in the presence of dipole perturbation of a single-null divertor Tokamak. This method is based on the idea that the magnetic field line trajectories in a divertor tokamak are mathematically equivalent to a single degree of freedom, time dependent Hamiltonian System, and that the basic features of motion near a separatrix broadened by asymmetric perturbations are generic for such Hamiltonian and near-Hamiltonian systems. The magnetic topology of a single-null divertor tokamak with the effects on dipole perturbations is represented by the Symmetric Simple Map followed by Dipole Map. We have found that as the amplitude of the dipole perturbation increases, the width of the stochastic layer also increases. At some critical value of the amplitude is reached, there is a catastrophic increase in the width of stochastic layer. This may have significant implications for tokamak divertor physics
Goldstein, Janna; Veitch, John; Sesana, Alberto; Vecchio, Alberto
2018-04-01
Super-massive black hole binaries are expected to produce a gravitational wave (GW) signal in the nano-Hertz frequency band which may be detected by pulsar timing arrays (PTAs) in the coming years. The signal is composed of both stochastic and individually resolvable components. Here we develop a generic Bayesian method for the analysis of resolvable sources based on the construction of `null-streams' which cancel the part of the signal held in common for each pulsar (the Earth-term). For an array of N pulsars there are N - 2 independent null-streams that cancel the GW signal from a particular sky location. This method is applied to the localisation of quasi-circular binaries undergoing adiabatic inspiral. We carry out a systematic investigation of the scaling of the localisation accuracy with signal strength and number of pulsars in the PTA. Additionally, we find that source sky localisation with the International PTA data release one is vastly superior than what is achieved by its constituent regional PTAs.
Seizure phenotypes, periodicity, and sleep-wake pattern of seizures in Kcna-1 null mice.
Wright, Samantha; Wallace, Eli; Hwang, Youngdeok; Maganti, Rama
2016-02-01
This study was undertaken to describe seizure phenotypes, natural progression, sleep-wake patterns, as well as periodicity of seizures in Kcna-1 null mutant mice. These mice were implanted with epidural electroencephalography (EEG) and electromyography (EMG) electrodes, and simultaneous video-EEG recordings were obtained while animals were individually housed under either diurnal (LD) condition or constant darkness (DD) over ten days of recording. The video-EEG data were analyzed to identify electrographic and behavioral phenotypes and natural progression and to examine the periodicity of seizures. Sleep-wake patterns were analyzed to understand the distribution and onset of seizures across the sleep-wake cycle. Four electrographically and behaviorally distinct seizure types were observed. Regardless of lighting condition that animals were housed in, Kcna-1 null mice initially expressed only a few of the most severe seizure types that progressively increased in frequency and decreased in seizure severity. In addition, a circadian periodicity was noted, with seizures peaking in the first 12h of the Zeitgeber time (ZT) cycle, regardless of lighting conditions. Interestingly, seizure onset differed between lighting conditions where more seizures arose out of sleep in LD conditions, whereas under DD conditions, the majority occurred out of the wakeful state. We suggest that this model be used to understand the circadian pattern of seizures as well as the pathophysiological implications of sleep and circadian disturbances in limbic epilepsies. Copyright © 2015 Elsevier Inc. All rights reserved.
Hara, Munetsugu; Takahashi, Tomoyuki; Mitsumasu, Chiaki; Igata, Sachiyo; Takano, Makoto; Minami, Tomoko; Yasukawa, Hideo; Okayama, Satoko; Nakamura, Keiichiro; Okabe, Yasunori; Tanaka, Eiichiro; Takemura, Genzou; Kosai, Ken-ichiro; Yamashita, Yushiro; Matsuishi, Toyojiro
2015-01-01
Methyl-CpG-binding protein 2 (MeCP2) is an epigenetic regulator of gene expression that is essential for normal brain development. Mutations in MeCP2 lead to disrupted neuronal function and can cause Rett syndrome (RTT), a neurodevelopmental disorder. Previous studies reported cardiac dysfunction, including arrhythmias in both RTT patients and animal models of RTT. In addition, recent studies indicate that MeCP2 may be involved in cardiac development and dysfunction, but its role in the developing and adult heart remains unknown. In this study, we found that Mecp2-null ESCs could differentiate into cardiomyocytes, but the development and further differentiation of cardiovascular progenitors were significantly affected in MeCP2 deficiency. In addition, we revealed that loss of MeCP2 led to dysregulation of endogenous cardiac genes and myocardial structural alterations, although Mecp2-null mice did not exhibit obvious cardiac functional abnormalities. Furthermore, we detected methylation of the CpG islands in the Tbx5 locus, and showed that MeCP2 could target these sequences. Taken together, these results suggest that MeCP2 is an important regulator of the gene-expression program responsible for maintaining normal cardiac development and cardiomyocyte structure. PMID:26073556
Canonical theory of spherically symmetric spacetimes with cross-streaming null dusts
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).
Orthoretroviral-like prototype foamy virus gag-pol expression is compatible with viral replication
Directory of Open Access Journals (Sweden)
Reh Juliane
2011-08-01
Full Text Available Abstract Background Foamy viruses (FVs unlike orthoretroviruses express Pol as a separate precursor protein and not as a Gag-Pol fusion protein. A unique packaging strategy, involving recognition of briding viral RNA by both Pol precursor and Gag as well as potential Gag-Pol protein interactions, ensures Pol particle encapsidation. Results Several Prototype FV (PFV Gag-Pol fusion protein constructs were generated to examine whether PFV replication is compatible with an orthoretroviral-like Pol expression. During their analysis, non-particle-associated secreted Pol precursor protein was discovered in extracellular wild type PFV particle preparations of different origin, copurifying in simple virion enrichment protocols. Different analysis methods suggest that extracellular wild type PFV particles contain predominantly mature p85PR-RT and p40IN Pol subunits. Characterization of various PFV Gag-Pol fusion constructs revealed that PFV Pol expression in an orthoretroviral manner is compatible with PFV replication as long as a proteolytic processing between Gag and Pol proteins is possible. PFV Gag-Pol translation by a HIV-1 like ribosomal frameshift signal resulted in production of replication-competent virions, although cell- and particle-associated Pol levels were reduced in comparison to wild type. In-frame fusion of PFV Gag and Pol ORFs led to increased cellular Pol levels, but particle incorporation was only marginally elevated. Unlike that reported for similar orthoretroviral constructs, a full-length in-frame PFV Gag-Pol fusion construct showed wildtype-like particle release and infectivity characteristics. In contrast, in-frame PFV Gag-Pol fusion with C-terminal Gag ORF truncations or non-removable Gag peptide addition to Pol displayed wildtype particle release, but reduced particle infectivity. PFV Gag-Pol precursor fusion proteins with inactivated protease were highly deficient in regular particle release, although coexpression of p71Gag
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)
Khanra, Kalyani; Chakraborty, Anindita; Bhattacharyya, Nandan
2015-01-01
The present study was aimed at determining the effects of alkylating and oxidative stress inducing agents on a newly identified variant of DNA polymerase beta (polβ Δ208-304) specific for ovarian cancer. Pol β Δ208-304 has a deletion of exons 11-13 which lie in the catalytic part of enzyme. We compared the effect of these chemicals on HeLa cells and HeLa cells stably transfected with this variant cloned into in pcDNAI/neo vector by MTT, colony forming and apoptosis assays. Polβ Δ208-304 cells exhibited greater sensitivity to an alkylating agent and less sensitivity towards H2O2 and UV when compared with HeLa cells alone. It has been shown that cell death in Pol β Δ208-304 transfected HeLa cells is mediated by the caspase 9 cascade. Exon 11 has nucleotidyl selection activity, while exons 12 and 13 have dNTP selection activity. Hence deletion of this part may affect polymerizing activity although single strand binding and double strand binding activity may remain same. The lack of this part may adversely affect catalytic activity of DNA polymerase beta so that the variant may act as a dominant negative mutant. This would represent clinical significance if translated into a clinical setting because resistance to radiation or chemotherapy during the relapse of the disease could be potentially overcome by this approach.
High density regimes and beta limits in JET
International Nuclear Information System (INIS)
Smeulders, P.
1990-01-01
Results are first presented on the density limit in JET discharges with graphite (C), Be gettered graphite and Be limiters. There is a clear improvement in the case of Be limiters. The Be gettered phase showed no increase in the gas fueled density limit, except with Ion Cyclotron Resonance Heating (ICRH), but, the limit changed character. During MARFE-formation, any further increase in density was prevented, leading to a soft density limit. The soft density limit was a function of input power and impurity content with a week dependence on q. Helium and pellet fuelled discharges exceeded the gas-fuelled global density limits, but essentially had the same edge limit. In the second part, results are presented of high β operation in low-B Double-Null (DN) X-point configurations with Be-gettered carbon target plates. The Troyon limit was reached during H-mode discharges and toroidal β values of 5.5% were obtained. At high beta, the sawteeth were modified and characterised by very rapid heat-waves and fishbone-like pre- and post-cursors with strongly ballooning character. 17 refs., 5 figs
Por que rir da Filosofia Política?: Abertura
Directory of Open Access Journals (Sweden)
Lessa Renato
1998-01-01
Full Text Available As diferentes intervenções que compuseram este debate têm como referência comum uma reflexão sobre os lugares da Filosofia Política na tradição disciplinar que designamos como Ciência Política. Recusando a perspectiva que dissocia a Filosofia Política da dimensão empiricamente orientada da disciplina, os argumentos apresentados destacam o papel de fertilização de formas de vida cumprido pela primeira. A agenda dos pesquisadores devotados à boa faina da investigação empírica foi, e segue sendo, em grande medida definida e configurada por exercícios prévios de invenção social e política e por decisões de ordem ontológica, epistemológica e retórica. Neste sentido, a distinção entre ciência e filosofia é, além de obscurantista e marcada por enorme otimismo epistemológico, sintoma de um desconhecimento forte com relação à história do conhecimento político.
Polímeros como modificadores asfálticos
Directory of Open Access Journals (Sweden)
Letícia SocaI da Silva
2009-12-01
Full Text Available
Neste trabalho foram preparadas diferentes misturas de ligante asfáltico modificado com polímeros. Foram utilizadas quatro amostras de polímeros, sendo duas de SBS, uma de SEBS e uma de Polietileno Modificado, as quais foram caracterizadas quanto a sua estrutura e propriedades térmicas através de técnicas de Ressonância Magnética Nuclear (RMN, Cromatografia por Permeação a Gel (GPC, Análise Termogravimétrica (TGA e Calorimetria Diferencial de Varredura (DSC. O ligante modificado foi avaliado quanto a sua viscosidade, retorno elástico, comportamento reológico e estabilidade à estocagem. Foram correlacionadas a estrutura química e as transições térmicas dos polímeros com as características do ligante modificado. Os polímeros do tipo SBS foram os melhores modificadores de asfalto, quando comparado com os demais polímeros avaliados.
El Desequilibrio de lo Político en Hegel
Directory of Open Access Journals (Sweden)
Juan Ignacio Arias Krause
2016-07-01
Full Text Available El problema político de la sociedad civil se fundamenta en su doble forma de manifestarse: por un lado, en ella se revela el carácter externo u objetivo del Estado y, por otro, produce una escisión al interior del mismo Estado. Tal problema que aparece como contradictorio (el ser exterior e interior a la vez es presentado en el pensamiento político de Hegel, en vistas a superar las dicotomías que en la teoría política moderna aparecían como insalvables. Esta superación Hegel la realiza mediante una interiorización de aquellos elementos que anteriormente habían sido marginados de la política, como son lo natural y el dominio privado, los que emergerían en la sociedad civil. En este artículo se exponen estos elementos en vistas a mostrar cómo es en este movimiento de interiorización y exteriorización de ellos donde se posibilita el acontecer de lo político.
Directory of Open Access Journals (Sweden)
Shalak V. F.
2011-10-01
Full Text Available Aim. Analyze the interaction between Lysyl-tRNA synthetase (LysRS and HIV-1 GagPol to know whether a particular N-terminal sequence of mitochondrial LysRS triggers a specific recognition with GagPol. Methods. Yeast two-hybrid analysis, immunoprecipitation. Results. We have shown that LysRS associates with the Pol domain of GagPol. Conclusions. A model of the assembly of the LysRS:tRNA3Lys:GagPol packaging complex is proposed.
On Fuzzy {beta}-I-open sets and Fuzzy {beta}-I-continuous functions
Energy Technology Data Exchange (ETDEWEB)
Keskin, Aynur [Department of Mathematics, Faculty of Science and Arts, Selcuk University, Campus, 42075 Konya (Turkey)], E-mail: akeskin@selcuk.edu.tr
2009-11-15
In this paper, first of all we obtain some properties and characterizations of fuzzy {beta}-I-open sets. After that, we also define the notion of {beta}-I-closed sets and obtain some properties. Lastly, we introduce the notions of fuzzy {beta}-I-continuity with the help of fuzzy {beta}-I-open sets to obtain decomposition of fuzzy continuity.
Beta-Catenin Stability in Breast Cancer
National Research Council Canada - National Science Library
Baswaran, Vijay
1999-01-01
.... beta-catenin also binds the adenomatous polyposis coli protein (APC). The tumor suppressor function of APC is suggested to depend in part on its ability to bind beta-catenin and to facilitate beta-catenin degradation by an unknown mechanism...
Beta-lactamases in Enterobacteriaceae in broilers
Dierikx, C.M.
2013-01-01
Resistance to cephalosprins due to the production of extended spectrum beta-lactamases (ESBLs) or plasmid mediated AmpC beta-lactamases is increasingly found in infections in humans outside the hospital. The genes encoding for these beta-lactamases are located on mobile DNA (plasmids), which can be