60,168 research outputs found
Linear Operator Inequality and Null Controllability with Vanishing Energy for Unbounded Control Systems
No full textWe 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
Null Subjects in Northeast English
No full textThis 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
Publication Bias Against Null Results
No full textStudies suggest a bias against the publication of null (p > .05) results. Instead of significance, we advocate reporting effect sizes and confidence intervals, and using replication studies. If statistical tests are used, power tests should accompany them.publication, bias, null results
Object drop in L3 acquisition
No full textThe topic of cross-linguistic differences regarding the overt or null expression of arguments has been considered both in first (L1) and second language (L2) acquisition. There is abundant literature on both subject and object drop with different language pairings but the issue has not been considered in third language (L3) acquisition. The main goal of this article is to analyse the L3 interlanguage of Basque-Spanish bilinguals regarding the acceptability and interpretation of null objects. The three languages involved in the study display different semantic requirements for the target structure, with Basque allowing for a null object option across-the-board, Spanish only under certain semantic conditions, and English disallowing it in the standard variety. Two trilingual, one bilingual and a control group (n = 119) rated experimental items embedded in context, presented in a written and aural format on a computer screen. Findings point to the successful acquisition of the target structure, as well as a clear influence of Spanish in the three experimental groups
Asymptotic null distributions of stationarity and nonstationarity
No full textThe purpose of this paper is to investigate the asymptotic null distribution of stationarity and nonstationarity tests when the distribution of the error term belongs to the normal domain of attraction of a stable law in any finite sample but the error term is an i.i.d. process with finite variance as T " 1. This local-to-finite variance setup is helpful to highlight the behavior of test statistics under the null hypothesis in the borderline or near borderline cases between finite and infinite variance and to assess the robustness of these test statistics to small departures from the standard finite variance context. From an empirical point of view, our analysis can be useful in settings where the (non)-existence of the (second) moments is not clear-cut, such as, for example, in the analysis of financial time series. A Monte Carlo simulation study is performed to improve our understanding of the practical implications of the limi theory we develop. The main purpose of the simulation experiment is to assess the size distortion of the unit root and stationarity tests under investigation.Stable distributions, unit root tests, stationarity tests, asymptotic distributions,local-to-finite variance, size distortion
Null controllability and the algebraic Riccati equation in Banach Spaces
No full textBy a recent result of Priola and Zabczyk, a null controllable linear system [y'(t) = Ay(t) + Bu(t)] in a Hilbert space E is null controllable with vanishing energy if and only if it is null controllable and the only positive self-adjoint solution of the associated algebraic Riccati equation [XA + A* X - XBB* X = 0] is the trivial solution X = 0. In this paper we extend this result to Banach spaces with an elementary proof which uses only reproducing kernel Hilbert space techniques. We also show that null controllability with vanishing energy implies null controllabilityDelft Institute of Applied MathematicsElectrical Engineering, Mathematics and Computer Scienc
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Frequency And Characteristics Of Circulating Cd4(+) Cd28(null) T Cells In Patients With Psoriasis
No full textFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Background Psoriasis is a chronic inflammatory disease that affects the skin. CD4(+) CD28(null) cells are a subset of T lymphocytes associated with systemic inflammation and increased cardiovascular disease risk, and may be involved in the pathogenesis of psoriasis. Objectives To study the features of circulating CD4(+) CD28(null) cells in patients with psoriasis, adjusted for the influence of known cardiovascular disease risk factors. Methods Forty-two patients with psoriasis and 42 controls entered the study. Peripheral blood mononuclear cells were analysed for the frequency of CD4(+) CD28(null) T lymphocytes and their expression of cytotoxic granules and homing receptors. Immunostaining for cutaneous cytotoxic granules was assessed in skin biopsies from 11 patients. Results There were no differences in the frequency of CD4(+) CD28(null) T cells between groups in all situations analysed. However, there was an increased number of cells expressing cytotoxic granules and a decreased number expressing CXCR3 in ex vivo samples of patients with psoriasis. A negative correlation was observed between the frequency of ex vivo CD4(+) CD28(null) cells and psoriasis severity. After clinical remission in nine patients, ex vivo CD4(+) CD28(null) lymphocytes expressing cytotoxic granules decreased. Perforin-, granzyme B- and granulysin- containing cells were found in skin lesions. Patients with psoriasis also had increased plasma levels of C-reactive protein. Conclusions These data suggest that cytotoxic cells, such as CD4(+) CD28(null) lymphocytes, within an inflammatory environment may play a role in the pathogenesis of psoriasis.17349981005Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
Frequency and characteristics of circulating Cd4(+) Cd28(null) T cells in patients with psoriasis
No full textPsoriasis is a chronic inflammatory disease that affects the skin. CD4(+) CD28(null) cells are a subset of T lymphocytes associated with systemic inflammation and increased cardiovascular disease risk, and may be involved in the pathogenesis of psoriasis. To study the features of circulating CD4(+) CD28(null) cells in patients with psoriasis, adjusted for the influence of known cardiovascular disease risk factors. Forty-two patients with psoriasis and 42 controls entered the study. Peripheral blood mononuclear cells were analysed for the frequency of CD4(+) CD28(null) T lymphocytes and their expression of cytotoxic granules and homing receptors. Immunostaining for cutaneous cytotoxic granules was assessed in skin biopsies from 11 patients. There were no differences in the frequency of CD4(+) CD28(null) T cells between groups in all situations analysed. However, there was an increased number of cells expressing cytotoxic granules and a decreased number expressing CXCR3 in ex vivo samples of patients with psoriasis. A negative correlation was observed between the frequency of ex vivo CD4(+) CD28(null) cells and psoriasis severity. After clinical remission in nine patients, ex vivo CD4(+) CD28(null) lymphocytes expressing cytotoxic granules decreased. Perforin-, granzyme B- and granulysin-containing cells were found in skin lesions. Patients with psoriasis also had increased plasma levels of C-reactive protein. These data suggest that cytotoxic cells, such as CD4(+) CD28(null) lymphocytes, within an inflammatory environment may play a role in the pathogenesis of psoriasis.Psoriasis is a chronic inflammatory disease that affects the skin. CD4(+) CD28(null) cells are a subset of T lymphocytes associated with systemic inflammation and increased cardiovascular disease risk, and may be involved in the pathogenesis of psoriasis.17349981005FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO -FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQsem informaçãosem informaçã
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