333,492 research outputs found
Null Subjects in Northeast English
Get PDFThis paper presents data and analysis relating to null subjects in spoken colloquial English.
While English is not a „pro-drop? language (i.e. subjects must usually be overt), a corpus of
speech collected on Tyneside and Wearside in 2007 shows that null subjects are permitted in
finite clauses in certain contexts. This paper analyses these examples and follow-up
questionnaires, and compares the data with the other types of null subject described in the
literature (pro-drop, topic-drop, early null subjects, aphasics? null subjects and „diary-drop?),
ultimately concluding that the colloquial English phenomenon is most closely related to diary-
drop
The appearance, motion, and disappearance of three-dimensional magnetic null points
No full textN.A.M. acknowledges support from NASA grants NNX11AB61G, NNX12AB25G, and NNX15AF43G; NASA contract NNM07AB07C; and NSF SHINE grants AGS-1156076 and AGS-1358342 to SAO. C.E.P. acknowledges support from the St Andrews 2013 STFC Consolidated grant.While theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co-located with a flow stagnation point, the introduction of asymmetry typically leads to non-ideal flows across the null point. To understand this behavior, we present exact expressions for the motion of three-dimensional linear null points. The most general expression shows that linear null points move in the direction along which the magnetic field and its time derivative are antiparallel. Null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non-ideal flows across topological boundaries. Null point motion is described intrinsically by parameters evaluated locally; however, global dynamics help set the local conditions at the null point. During a bifurcation of a degenerate null point into a null-null pair or the reverse, the instantaneous velocity of separation or convergence of the null-null pair will typically be infinite along the null space of the Jacobian matrix of the magnetic field, but with finite components in the directions orthogonal to the null space. Not all bifurcating null-null pairs are connected by a separator. Furthermore, except under special circumstances, there will not exist a straight line separator connecting a bifurcating null-null pair. The motion of separators cannot be described using solely local parameters because the identification of a particular field line as a separator may change as a result of non-ideal behavior elsewhere along the field line.Peer reviewe
Frataxin null mutants of arabidopsis are embryo lethals
No full textFrataxin is a nuclear encoded protein targeted to the mitochondrial matrix. In humans, frataxin deficiency
is associated with Friedreich’s ataxia, a neurodegenerative and cardiac disorder characterized by
accumulation of iron in the mitochondria and a diminished activity of various mitochondrial proteins,
including aconitase. Yeast cells lacking frataxin show a complex respiratory deficient phenotype,
defective in the maturation of mitochondrial Fe/S enzymes, hypersensitivity to oxidative stress, instability
of mtDNA and defects in heme biosynthesis. It has been proposed that frataxin has ferroxidase activity
and iron storage properties which may protect the mitochondria from iron toxicity, and that it also acts as
a chaperone to donate iron to the proteins involved in the two major pathways of iron utilization, Fe/S
cluster assembly and heme synthesis. Recently, an Arabidopsis gene (AtFH) highly similar to the human
frataxin gene and possessing a mitochondrial targeting sequence has been described (Busi et al. 2004):
AtFH is able to complement a yeast frataxin null mutant and in the plant is mainly expressed in flowers.
We identified in the Salk collection two T-DNA insertions in the AtFH gene and characterized genetically
the two mutants. Upon selfing heterozygous plants, we cannot recover in the progeny homozygote null
seeds while homozygous wt and heterozygous seeds were in a ratio 1: 2 (as observed after PCR analysis).
The ratio was consistent with lethality of the homozygous null genotypes during embryogenesis.
Accordingly we analyze the pattern of embryo development in siliques segregating homozygous null
embryos: an early arrest at the 8-16 cells stage was consistently observed
null
No full textEl análisis de la reconocida obra de la música popular cubana titulada Guantanamera, mediante la investigación de las bibliografías, fonogramas y partituras que documentan la génesis de dicha pieza, revela al verdadero autor de la melodía con la que se cantan los versos de José Martí en la mencionada canción y demuestra las causas que provocaron la incertidumbre acerca de la autoría de dicha melodía.Con esta investigación concluyo que la melodía con la que se cantan los versos de José Martí en la pieza Guantanamera es una creación del compositor hispano–cubano Julián Orbón (1925–1991) y no de Joseíto Fernández como se ha repetido acríticamente. Igualmente, concluyo que la melodía de la tonada conocida con el título de Guajira guantanamer, popularizada con textos en décimas improvisadas y adjudicada a Joseíto Fernández, es bien diferente a la melodía utilizada por Orbón y popularizada por Pete Seeger para cantar los versos de Martí. Por causas políticas el Estado Cubano ha difundido el desacierto de que el autor de la melodía con la que se cantan los versos de José Martí en la pieza titulada Guantanamera es Joseíto Fernández y que Julián Orbón solamente adaptó los versos de Martí a la melodía de Fernández.An analysis of bibliography, phonograms and scores documenting the genesis of the well–known Cuban folk song Guantanamera, reveals the identity of its true author, and demonstrates the causes of the uncertainty that surrounds the authorship of the famous setting of José Marti’s poem. The author of this article concludes that the piece is an original creation of the Cuban–Hispanic composer Julián Orbón (1925–1991), rather than Joseíto Fernández, to whom it has been repeatedly attributed.The article concludes as well, that the melody of the tune known as Guajira guantanamera –made famous as a setting of improvised decasyllabic verses, and also attributed to Joseíto Fernández– is completely different from the one used by Orbón, which was the one internationalized by Pete Seeger with Marti’s words.Political causes motivated Cuban government to broadcast (wrongly) that the author of the tune, with words by José Martí, known as Guantanamera is Joseíto Fernández, and that Julián Orbón was responsible only for the setting of Martí’s poem to Fernández melody
Linear Operator Inequality and Null Controllability with Vanishing Energy for Unbounded Control Systems
Get PDFWe consider a linear boundary or point control system on a Hilbert space which is null controllable at some time . To every initial state we associate the minimal ``energy'' needed to transfer to in a time (``energy'' of a control being the square of its norm). Clearly, it decreases with the control time . We shall prove that, under suitable spectral properties of the linear system operator, the minimal energy converges to for $ T\to+\infty
On Einstein null hypersurfaces of -space forms
Get PDFWe show that ascreen null hypersurfaces of an (n+2)-dimensional Lorentzian concircular structure (LCS)_{n+2}-manifold admits an induced Ricci tensor. We, therefore, prove, under some geometric conditions, that an Einstein ascreen null hypersurface is locally a product of null curves and products of spheres
A Panel Test of Purchasing Power Parity Under the Null of Stationarity
No full textPurchasing 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
Null and overt subject biases in Spanish and Italian: a cross-linguistic comparison
No full textOver the last twenty years a great deal of linguistic research has investigated how anaphoric expressions retrieve their antecedents in the discourse showing that a variety of pragmatic factors together with grammatical and cognitive constraints contribute in determining the distribution of different types of expressions. A particularly interesting case for the study of such phenomena is that of Null Subjec
Interpreting null findings from trials of alcohol brief interventions
No full textThe effectiveness of alcohol brief intervention (ABI) has been established by a succession of meta-analyses but, because the effects of ABI are small, null findings from randomized controlled trials are often reported and can sometimes lead to skepticism regarding the benefits of ABI in routine practice. This article first explains why null findings are likely to occur under null hypothesis significance testing (NHST) due to the phenomenon known as ‘the dance of the p-values’. A number of misconceptions about null findings are then described, using as an example the way in which the results of the primary care arm of a recent cluster randomized trial of ABI in England (the SIPS project) have been misunderstood. These misinterpretations include the fallacy of ‘proving the null hypothesis’ that lack of a significant difference between the means of sample groups can be taken as evidence of no difference between their population means, and the possible effects of this and related misunderstandings of the SIPS findings are examined. The mistaken inference that reductions in alcohol consumption seen in control groups from baseline to follow-up are evidence of real effects of control group procedures is then discussed and other possible reasons for such reductions, including regression to the mean, research participation effects, historical trends, and assessment reactivity, are described. From the standpoint of scientific progress, the chief problem about null findings under the conventional NHST approach is that it is not possible to distinguish ‘evidence of absence’ from ‘absence of evidence’. By contrast, under a Bayesian approach, such a distinction is possible and it is explained how this approach could classify ABIs in particular settings or among particular populations as either truly ineffective or as of unknown effectiveness, thus accelerating progress in the field of ABI research
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