48,960 research outputs found
A Proposed Hybrid Effect Size Plus p -Value Criterion: Empirical Evidence Supporting its Use
DOI: 10.1080/00031305.2018.1564697
When the editors of Basic and Applied Social Psychology effectively banned the use of null hypothesis significance testing (NHST) from articles published in their journal, it set off a fire-storm of discussions both supporting the decision and defending the utility of NHST in scientific research. At the heart of NHST is the p-value which is the probability of obtaining an effect equal to or more extreme than the one observed in the sample data, given the null hypothesis and other model assumptions. Although this is conceptually different from the probability of the null hypothesis being true, given the sample, p-values nonetheless can provide evidential information, toward making an inference about a parameter. Applying a 10,000-case simulation described in this article, the authors found that p-values’ inferential signals to either reject or not reject a null hypothesis about the mean (α = 0.05) were consistent for almost 70% of the cases with the parameter’s true location for the sampled-from population. Success increases if a hybrid decision criterion, minimum effect size plus p-value (MESP), is used. Here, rejecting the null also requires the difference of the observed statistic from the exact null to be meaningfully large or practically significant, in the researcher’s judgment and experience. The simulation compares performances of several methods: from p-value and/or effect size-based, to confidence-interval based, under various conditions of true location of the mean, test power, and comparative sizes of the meaningful distance and population variability. For any inference procedure that outputs a binary indicator, like flagging whether a p-value is significant, the output of one single experiment is not sufficient evidence for a definitive conclusion. Yet, if a tool like MESP generates a relatively reliable signal and is used knowledgeably as part of a research process, it can provide useful information
Mechanical adaptations of cleavers (Galium aparine)
• Background and Aims
Cleavers (Galium aparine) is a fast-growing herbaceous annual with a semi-self-supporting, scrambling-ascending growth habit. Mature plants often use upright species for support. It is common in hedgerows and on waste ground. This study aims to characterize the mechanical behaviour of the stem and roots of cleavers and relate this to the arrangement of structural tissue, the net microfibrillar orientations in the cell walls, and plant growth habit.
• Methods The morphology and mechanics of mature cleavers was investigated using plants grown in pots and ones collected from the grounds at the University of Lincoln, Lincoln, UK. Tensile tests were carried out on the stem and the basal section of the first-order lateral roots. The net orientation of cellulose microfibrils in the cell walls was investigated using polarized light microscopy.
• Key Results Results show that the basal regions of the stem and first-order lateral roots were highly extensible. Breaking strains of 24 ± 7 % were recorded for the stem base and 28 ± 6 % for the roots. Anatomical observations showed that the lower stem (base + 100 mm) was circular in cross-section with a solid central core of vascular tissue, whereas further up the stem the transverse section showed a typical four-angled shape with a ring-like arrangement of vascular tissue and sclerenchyma bundles in the corners. The net orientation of wall microfibrils in the secondary xylem diverges from the longitudinal by between 8 and 9°.
• Conclusions The basal region of the stem of cleavers is highly extensible, but the mechanism by which the stem is able to withstand such high breaking strains is unclear; reorientation of the cellulose fibrils in the stem along the axis of loading is not thought to be responsible.
Key words: Anatomy, adaptation, cleavers, Galium aparine, growth habit, mechanics, cellulose microfibril orientation, extensibilit
Research in life sciences instrumentation pertinent to studies in space biology Quarterly progress report, 1 Apr. - 30 Jun. 1967
Brain probes, multichannel telemetry devices, and telemetric brain temperature sensors for space biology studie
New Calculations in Dirac Gaugino Models: Operators, Expansions, and Effects
In this work we calculate important one loop SUSY-breaking parameters in
models with Dirac gauginos, which are implied by the existence of heavy
messenger fields. We find that these SUSY-breaking effects are all related by a
small number of parameters, thus the general theory is tightly predictive. In
order to make the most accurate analyses of one loop effects, we introduce
calculations using an expansion in SUSY breaking messenger mass, rather than
relying on postulating the forms of effective operators. We use this expansion
to calculate one loop contributions to gaugino masses, non-holomorphic SM
adjoint masses, new A-like and B-like terms, and linear terms. We also test the
Higgs potential in such models, and calculate one loop contributions to the
Higgs mass in certain limits of R-symmetric models, finding a very large
contribution in many regions of the -less MSSM, where Higgs fields couple
to standard model adjoint fields.Comment: 16 pages, 10 figure
Modeling material failure with a vectorized routine
The computational aspects of modelling material failure in structural wood members are presented with particular reference to vector processing aspects. Wood members are considered to be highly orthotropic, inhomogeneous, and discontinuous due to the complex microstructure of wood material and the presence of natural growth characteristics such as knots, cracks and cross grain in wood members. The simulation of strength behavior of wood members is accomplished through the use of a special purpose finite element/fracture mechanics routine, program STARW (Strength Analysis Routine for Wood). Program STARW employs quadratic finite elements combined with singular crack tip elements in a finite element mesh. Vector processing techniques are employed in mesh generation, stiffness matrix formation, simultaneous equation solution, and material failure calculations. The paper addresses these techniques along with the time and effort requirements needed to convert existing finite element code to a vectorized version. Comparisons in execution time between vectorized and nonvectorized routines are provided
Megaton Water Cerenkov Detectors and Astrophysical Neutrinos
Although formal proposals have not yet been made, the UNO and
Hyper-Kamiokande projects are being developed to follow-up the tremendously
successful program at Super-Kamiokande using a detector that is 20-50 times
larger. The potential of such a detector to continue the study of astrophysical
neutrinos is considered and contrasted with the program for cubic kilometer
neutrino observatories.Comment: 4 pages Submitted to the Proceedings of the 2004 Neutrino Oscillation
Workshop, Otranto Ital
States of fermionic atoms in an optical superlattice across a Feshbach resonance
We investigate states of fermionic atoms across a broad Feshbach resonance in
an optical superlattice which allows interaction only among a small number of
lattice sites. The states are in general described by superpositions of atomic
resonating valence bonds and dressed molecules. As one scans the magnetic
field, level crossing is found between states with different symmetry
properties, which may correspond to a quantum phase transition in the many-body
case.Comment: 10 pages, 11 figure
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