Paolo Guagliardo, Leonid Libkin,
... with marked nulls carry over to SQL, because SQL nulls can be interpreted as Codd nulls, which are ... the same unknown value. For such queries, interpreting SQL nulls as Codd nulls would incorrectly change the semantics ... understand which queries preserve the Codd interpretation of SQL nulls. We show, however, that the class of relational ...
Tópico(s): Semantic Web and Ontologies
2018 - Elsevier BV | Information Systems
... preference to a basic rewriting rule. After introducing SQL-type null values, their impact on the translation is thoroughly ... preference to a basic rewriting rule. After introducing SQL-type null values, their impact on the translation is thoroughly ...
Tópico(s): Semantic Web and Ontologies
1990 - Association for Computing Machinery | ACM Transactions on Database Systems
Abstract We introduce a new diagnostic for the null tests of dynamical dark energy alongside two other combined equivalent diagnostics. These diagnostics are useful, especially when we include anisotropic baryon acoustic oscillation (BAO) data in an analysis, to quantify the deviations from the standard ΛCDM model. We also consider another diagnostic for isotropic BAO observations. These null tests are independent of any late-time dark energy model or parametrization. With these diagnostics, we study ...
Tópico(s): Galaxies: Formation, Evolution, Phenomena
2024 - Institute of Physics | Journal of Cosmology and Astroparticle Physics
Luca Ciambelli, Laurent Freidel, Robert G. Leigh,
A bstract We initiate a study of gravity focusing on generic null hypersurfaces, non-perturbatively in the Newton coupling. We present an off-shell account of the extended phase space of the theory, which includes the expected spin-2 data as well as spin-0, spin-1 and arbitrary matter degrees of freedom. We construct the charges and the corresponding kinematic Poisson brackets, employing a Beltrami parameterization of the spin-2 modes. We explicitly show that the constraint algebra closes, the details ...
Tópico(s): Pulsars and Gravitational Waves Research
2024 - Springer Nature | Journal of High Energy Physics
A bstract Recently, evidence of stochastic gravitational wave background (SGWB) signals observed by pulsar timing array (PTA) collaborations, has prompted investigations into their origins. We explore the compatibility of a proposed inflationary scenario, incorporating an intermediate null energy condition (NEC)-violating phase, with the PTA observations. The NEC violation potentially amplifies the primordial tensor power spectrum, offering a promising explanation for PTA observations. Numerical analyses, ...
Tópico(s): Geophysics and Gravity Measurements
2024 - Springer Nature | Journal of High Energy Physics
Daniel J. Reardon, Andrew Zic, R. M. Shannon, Valentina Di Marco, G. Hobbs, Agastya Kapur, M. E. Lower, Rami Mandow, H. Middleton, Matthew T. Miles, Axl F. Rogers, Jacob Askew, M. Bailes, N. D. R. Bhat, A D Cameron, M. Kerr, Atharva Kulkarni, R. N. Manchester, Rowina S Nathan, Craig Russell, S. Osłowski, X. J. Zhu,
Abstract The noise in millisecond pulsar (MSP) timing data can include contributions from observing instruments, the interstellar medium, the solar wind, solar system ephemeris errors, and the pulsars themselves. The noise environment must be accurately characterized in order to form the null hypothesis from which signal models can be compared, including the signature induced by nanohertz-frequency gravitational waves (GWs). Here we describe the noise models developed for each of the MSPs in the Parkes ...
Tópico(s): Cosmology and Gravitation Theories
2023 - IOP Publishing | The Astrophysical Journal Letters
Mark M. Churchland, Krishna V. Shenoy,
Tópico(s): Neuroscience and Neural Engineering
2024 - Nature Portfolio | Nature reviews. Neuroscience
Abstract Survey experiments often yield intention-to-treat effects that are either statistically and/or practically “non-significant.” There has been a commendable shift toward publishing such results, either to avoid the “file drawer problem” and/or to encourage studies that conclude in favor of the null hypothesis. But how can researchers more confidently adjudicate between true, versus erroneous, nonsignificant results? Guidance on this critically important question has yet to be synthesized into ...
Tópico(s): Social and Intergroup Psychology
2024 - Cambridge University Press | Journal of Experimental Political Science
Feng ZHANG, Yu Pi, Xiaobao LI,
摘要: 运用事件相关电位技术和时间自我参照任务, 通过两个系列实验探讨了大学生的个体时间自我评价和集体时间自我评价。结果显示, 被试采用更多积极词、更少消极词来评价过去、现在和未来的个体自我和集体自我, 个体自我评价在过去、现在和未来维度上存在积极递增效应; 个体自我和集体自我在过去和现在维度上的消极词比积极词诱发了更大LPC波幅, 而未来维度上的积极词和消极词之间的LPC波幅无显著差异。这表明, 中国大学生的个体时间自我评价和集体时间自我评价均具有跨时间的积极偏向。而且, 个体与集体时间自我评价在神经生理水平上都存在负偏向效应。因此, 中国大学生的集体时间自我评价与个体时间自我评价具有相似的认知神经特点, 在一定程度上为依存型自我建构理论提供了支持证据。
Tópico(s): Cognitive Science and Mapping
2024 - Science Press | Acta Psychologica Sinica
In quantum field theory, the Dyson-Schwinger equations are an infinite set of coupled equations relating n-point Green's functions in a self-consistent manner. They have found important applications in nonperturbative studies, ranging from quantum chromodynamics and hadron physics to strongly correlated electron systems. However, they are notoriously formidable to solve. One of the main obstacles is that a finite truncation of the infinite system is underdetermined. Recently, Bender et al. [Phys. ...
Tópico(s): Quantum chaos and dynamical systems
2023 - American Physical Society | Physical Review Letters
Abstract Identification of standard mediated effects such as the natural indirect effect relies on heavy causal assumptions. By circumventing such assumptions, so-called randomised interventional indirect effects have gained popularity in the mediation literature. Here, I introduce properties one might demand of an indirect effect measure in order for it to have a true mediational interpretation. For instance, the sharp null criterion requires an indirect effect measure to be null whenever no individual- ...
Tópico(s): Health Systems, Economic Evaluations, Quality of Life
2023 - Oxford University Press | Journal of the Royal Statistical Society Series B (Statistical Methodology)
Yannis Angelopoulos, Stefanos Aretakis, Dejan Gajic,
In this paper, we prove precise late-time asymptotics for solutions to the wave equation supported on angular frequencies greater or equal to $\ell$ on the domain of outer communications of subextremal Reissner-Nordstr\"om spacetimes up to and including the event horizon. Our asymptotics yield, in particular, sharp upper and lower decay rates which are consistent with Price's law on such backgrounds. We present a theory for inverting the time operator and derive an explicit representation of the leading- ...
Tópico(s): Cosmology and Gravitation Theories
2023 - Birkhäuser | Annales Henri Poincaré
Summary Given a large number of test statistics, a small proportion of which represent departures from the relevant null hypothesis, a simple rule is given for choosing those statistics that are indicative of departure. It is based on fitting by moments a mixture model to the set of test statistics and then deriving an estimated likelihood ratio. Simulation suggests that the procedure has good properties when the departure from an overall null hypothesis is not too small.
Tópico(s): Statistical Methods and Bayesian Inference
2004 - Oxford University Press | Journal of the Royal Statistical Society Series B (Statistical Methodology)
Timothy A. Reinhardt, John D. Lippolis, Gary E. Shull, Ronald L. Horst,
The means by which calcium is transported into the milk produced by mammary glands is a poorly understood process. One hypothesis is that it occurs during exocytosis of secretory products via the Golgi pathway, consistent with the observation that the SPCA1 Ca2+-ATPase, which is expressed in the Golgi, is induced in lactating mammary tissue. However, massive up-regulation of the PMCA2bw plasma membrane Ca2+-ATPase also occurs during lactation and is more strongly correlated with increases in milk ...
Tópico(s): Trace Elements in Health
2004 - Elsevier BV | Journal of Biological Chemistry
Chao Qi, Papreddy Kashireddy, Yiwei Tony Zhu, Sambasiva M. Rao, Yi-Jun Zhu,
To investigate the role of nuclear receptor coactivator peroxisome proliferator-activated receptor-interacting protein (PRIP) in mammary gland development, we generated a conditional null mutation of PRIP in mammary glands. In PRIP-deficient mammary glands, the elongation of ducts during puberty was not affected, but the numbers of ductal branches were decreased, a condition that persisted long after puberty, indicating that the potential of ductal branching was impaired. During pregnancy, PRIP-deficient ...
Tópico(s): Metabolism, Diabetes, and Cancer
2004 - Elsevier BV | Journal of Biological Chemistry
Barbara J. Morley, Jorge F. Rodriguez‐Sierra,
The α7 nicotinic acetylcholine receptor (nAChR) is heavily expressed in the mammalian brain. On a molecular level, the α7 nAChR may have a diversity of functions, but it is not known if these molecular events translate into phenotypes. The null mutant mouse is viable and generally normal. Here, we report a phenotype for the α7 nAChR null mutant mouse. The α7 nAChR is obligatory for the synchronization of an important biological rhythm, the female estrous cycle. The female null mutant mouse has asynchronous ...
Tópico(s): Receptor Mechanisms and Signaling
2004 - Elsevier BV | Brain Research
Produção Nacional
Revisado por pares
Vincent P. Diego, Laura Almasy, Thomas D. Dyer, Júlia Maria Pavan Soler, John Blangero,
Abstract Background Using univariate and multivariate variance components linkage analysis methods, we studied possible genotype × age interaction in cardiovascular phenotypes related to the aging process from the Framingham Heart Study. Results We found evidence for genotype × age interaction for fasting glucose and systolic blood pressure. Conclusions There is polygenic genotype × age interaction for fasting glucose and systolic blood pressure and quantitative trait locus × age interaction for a linkage ...
Tópico(s): Gene Regulatory Network Analysis
2003 - BioMed Central | BMC Genomic Data
Several tests of molecular phylogenies have been proposed over the last decades, but most of them lead to strikingly different P-values. I propose that such discrepancies are principally due to different forms of null hypotheses. To support this hypothesis, two new tests are described. Both consider the composite null hypothesis that all the topologies are equidistant from the true but unknown topology. This composite hypothesis can either be reduced to the simple hypothesis at the least favorable ...
Tópico(s): Chromosomal and Genetic Variations
2003 - Oxford University Press | Systematic Biology
Zhigang Wang, Warren Thorngate,
Two Monte Carlo simulations were developed to investigate the social consequences of balancing sentiment relations among triads of members of a larger group, when balancing one triad can imbalance others. Using assumptions of Balance Theory (Heider, 1958), random starting combinations of liking, disliking and no relations among 9, 16 or 25 people were iteratively adjusted to determine if the relations ever settled to a steady state and what subgroups might emerge. Results show that, regardless of ...
Tópico(s): Cognitive and psychological constructs research
2003 - University of Surrey | Journal of Artificial Societies and Social Simulation
Timothy J. Cole, Nicola M. Solomon, Rosemary van Driel, Julie A. Monk, Anthony D. Bird, Samantha J. Richardson, Rodney J. Dilley, Stuart B. Hooper,
Glucocorticoids provide important signals for maturation of the fetal lung and antenatal glucocorticoids are used to reduce the respiratory insufficiency suffered by preterm infants. To further understand the role of glucocorticoids in fetal lung maturation, we have analyzed mice with a targeted null mutation for the glucocorticoid receptor (GR) gene, which severely retards lung development. The lungs of fetal GR-null mice have increased lung weight and DNA content, are condensed and hypercellular, ...
Tópico(s): Helicobacter pylori-related gastroenterology studies
2003 - American Thoracic Society | American Journal of Respiratory Cell and Molecular Biology
Wei Qu, Bhalchandra A. Diwan, Jie Liu, Robert A. Goyer, Tammy Dawson, John L. Horton, M. George Cherian, Michael P. Waalkes,
Susceptibility to lead toxicity in MT-null mice and cells, lacking the major forms of the metallothionein (MT) gene, was compared to wild-type (WT) mice or cells. Male MT-null and WT mice received lead in the drinking water (0 to 4000 ppm) for 10 to 20 weeks. Lead did not alter body weight in any group. Unlike WT mice, lead-treated MT-null mice showed dose-related nephromegaly. In addition, after lead exposure renal function was significantly diminished in MT-null mice in comparison to WT mice. MT- ...
Tópico(s): Environmental Toxicology and Ecotoxicology
2002 - Elsevier BV | American Journal Of Pathology
Azin Agah, Themis R. Kyriakides, Jack Lawler, Paul Börnstein,
Thrombospondin (TSP) 1 and 2, share the same overall structure and interact with a number of the same cell-surface receptors. In an attempt to elucidate their biological roles more clearly, we generated double-TSP1/TSP2-null animals and compared their phenotype to those of TSP1- and TSP2-null mice. Double-null mice exhibited an apparent phenotype that primarily represented the sum of the abnormalities observed in the single-null mice. However, surprisingly, the wound-healing response in double-null ...
Tópico(s): Lymphatic System and Diseases
2002 - Elsevier BV | American Journal Of Pathology
Given a real random-like time series, the first question to answer is whether the data carry any information over time, i.e. whether the successive samples are correlated. Using standard statistical testing, the least interesting null hypothesis of white noise has to be rejected if the analysis of the time series should be of any use at all. Further, if nonlinear methods are to be used, e.g. a sophisticated nonlinear prediction method instead of a linear autoregressive model, the null hypothesis ...
Tópico(s): Neural Networks and Applications
2002 - Springer Nature | Studies in computational finance
Takako Okuwa, Takahiro Katayama, Akinori Takano, Ken-Ichi Kodaira, Hiroo Yasukawa,
Countin, a cell‐counting factor in Dictyostelium discoideum , is considered to limit the maximum size of the multicellular structure, because a countin null strain forms a huge fruiting body compared to that of the wild‐type. A novel gene, countin2 , that is highly homologous to countin (40% identity in amino acid sequence) was identified in the D. discoideum genome. The countin2 null strain formed a 1.7‐fold higher number of the aggregates, resulting in smaller fruiting bodies compared with those of ...
Tópico(s): Skin and Cellular Biology Research
2001 - Wiley | Development Growth & Differentiation
Akira Ikeda, Miyako Ueguchi‐Tanaka, Yutaka Sonoda, Hidemi Kitano, Masaji Koshioka, Yuzo FUTSUHARA, Makoto Matsuoka, Junji Yamaguchi,
The rice slender mutant (slr1-1) is caused by a single recessive mutation and results in a constitutive gibberellin (GA) response phenotype. The mutant elongates as if saturated with GAs. In this mutant, (1) elongation was unaffected by an inhibitor of GA biosynthesis, (2) GA-inducible α-amylase was produced by the aleurone layers without gibberellic acid application, and (3) endogenous GA content was lower than in the wild-type plant. These results indicate that the product of the SLR1 gene is an intermediate ...
Tópico(s): Polysaccharides and Plant Cell Walls
2001 - Oxford University Press | The Plant Cell
Jian Yang, Yoshio Yamaguchi, Hiroyoshi Yamada, W.‐M. Boerner, H. Mott, Yingning Peng,
In a co- or cross-polarized channel, the polarization states of the transmitting and receiving antennas are the same or orthogonal, and the corresponding target nulls (i.e., the co-pol nulls or x-pol nulls) are defined as the polarization states of the transmitting antenna such that the received power equals zero. However, no systematic studies have been carried out to solve the problem of the corresponding target nulls if the polarization states of the transmitting and receiving antennas are independent. ...
Tópico(s): Microwave Imaging and Scattering Analysis
2001 - Institute of Electrical and Electronics Engineers | IEEE Transactions on Geoscience and Remote Sensing
Scott J. Bultman, Tom Gebuhr, Della Yee, Christian La Mantia, Jackie Nicholson, Anita C. Gilliam, Filippo Randazzo, Daniel Metzger, Pierre Chambon, Gerald R. Crabtree, Terry Magnuson,
Abstract Mammalian SWI/SNF complexes utilize either brahma (Brm) or brahma-related gene 1 (Brg1) catalytic subunits to remodel nucleosomes in an ATP-dependent manner. Brm was previously shown to be dispensable, suggesting that Brm and Brg1 are functionally redundant. To test this hypothesis, we have generated a Brg1 null mutation by gene targeting, and, surprisingly, homozygotes die during the periimplantation stage. Furthermore, blastocyst outgrowth studies indicate that neither the inner cell mass nor trophectoderm ...
Tópico(s): interferon and immune responses
2000 - Elsevier BV | Molecular Cell
Paul Whiteaker, Michael J. Marks, Sharon R. Grady, Ying Lü, Marina R. Picciotto, Jean‐Pierre Changeux, Allan C. Collins,
Tópico(s): Cholinesterase and Neurodegenerative Diseases
2000 - Elsevier BV | European Journal of Pharmacology
We prove that it is consistent that the covering number of the ideal of measure zero sets has countable cofinality. 0. Introduction. In the present paper we show that it is consistent that the covering of the null ideal has countable cofinality. Recall that the covering number of the null ideal (i.e. the ideal of measure zero sets) is defined as cov(null) = min n |P| : P null and ( A2P A = R (= ! 2) o
Tópico(s): Mathematical and Theoretical Analysis
2000 - Polish Academy of Sciences | Fundamenta Mathematicae
Eric S. Davis, Wancen Mu, Stuart Lee, Mikhail G. Dozmorov, Michael I. Love, Douglas H. Phanstiel,
Abstract Motivation Deriving biological insights from genomic data commonly requires comparing attributes of selected genomic loci to a null set of loci. The selection of this null set is non-trivial, as it requires careful consideration of potential covariates, a problem that is exacerbated by the non-uniform distribution of genomic features including genes, enhancers, and transcription factor binding sites. Propensity score-based covariate matching methods allow the selection of null sets from ...
Tópico(s): Advanced Causal Inference Techniques
2023 - Oxford University Press | Bioinformatics