5,956 research outputs found
Force-Time Differences between Ballistic and Non-Ballistic Half-Squats.
The purpose of this study was to examine the force-time differences between concentric-only half-squats (COHS) performed with ballistic (BAL) or non-ballistic (NBAL) intent across a range of loads. Eighteen resistance-trained men performed either BAL or NBAL COHS at 30%, 50%, 70%, and 90% of their one repetition maximum (1RM) COHS. Relative peak force (PF) and relative impulse from 0⁻50 ms (Imp50), 0⁻90 ms (Imp90), 0⁻200 ms (Imp200), and 0⁻250 ms (Imp250) were compared using a series of 2 × 4 (intent × load) repeated measures ANOVAs with Bonferroni post hoc tests. Cohen\u27s d effect sizes were calculated to provide measures of practical significance between the BAL and NBAL COHS and each load. BAL COHS produced statistically greater PF than NBAL COHS at 30% (d = 3.37), 50% (d = 2.88), 70% (d = 2.29), and 90% 1RM (d = 1.19) (all p \u3c 0.001). Statistically significant main effect differences were found between load-averaged BAL and NBAL COHS for Imp90 (p = 0.006, d = 0.25), Imp200 (p = 0.001, d = 0.36), and Imp250 (p \u3c 0.001, d = 0.41), but not for Imp50 (p = 0.018, d = 0.21). Considering the greater PF and impulse observed during the BAL condition, performing COHS with BAL intent may provide a favorable training stimulus compared to COHS performed with NBAL intent
The Assembly of Diversity in the Morphologies and Stellar Populations of High-Redshift Galaxies
We have studied the evolution in the morphologies, sizes, stellar-masses,
colors, and internal color dispersion (ICD) of galaxies at z=1 and 2.3, using a
near-IR, flux-limited catalog for the HDF-N. At z=1 most luminous galaxies have
morphologies of early-to-mid Hubble-types, and many show transformations
between their rest-frame UV-optical morphologies. Galaxies at z=2.3 have
compact and irregular morphologies with no clearly evident Hubble-sequence
candidates. The mean galaxy size grows from z=2.3 to 1 by 40%, and the density
of galaxies larger than 3 kpc increases by 7 times. At z=1, the size-luminosity
distribution is broadly consistent with that of local galaxies, with passive
evolution. However, galaxies at z=2.3 are smaller than the large present-day
galaxies, and must continue to grow in size and stellar mass. We have measured
the galaxies' UV-optical ICD, which quantifies differences in morphology and
the relative amount of on-going star-formation. The mean and scatter in
galaxies' total colors and ICD increase from z=2.3 to 1. At z=1 many galaxies
with large ICD are spirals, with a few irregular systems. Few z=2.3 galaxies
have high ICD, and those that do are actively merging. We interpret this as
evidence for the presence of older and more diverse stellar populations at z=1
that are not generally present at z>2. We conclude that the star-formation
histories of galaxies at z>2 are dominated by discrete, recurrent bursts, which
quickly homogenize the galaxies' stellar content, and are possibly associated
with mergers. The increase in the stellar-population diversification by z<1.4
implies that merger-induced starbursts occur less frequently than at higher
redshifts, and more quiescent star-forming modes dominate. This transition
coincides with the emergence of Hubble-sequence galaxies. [Abridged]Comment: Accepted for publication in the Astrophysical Journal. 20 pages, in
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Neighbourhoods, classes, and near sets
The article calls attention to the relationship between neighbourhoods and tolerance classes in the foundations of tolerance near sets. A particular form of tolerance relation is given by way of introduction to descriptively "-near sets. Neighbourhoods and tolerance classes have practical applications in digital image analysis.http://www.m-hikari.com/ams/ams-2011/ams-33-36-2011/henryAMS33-36-2011.pd
Metric free nearness measure using description-based neighbourhoods
Preprint versionThe focus of this paper is on a metric free nearness measure for quantifying the descriptive nearness of digital images. Regions of Interest (ROI) play an important role in discerning perceptual similarity within a single image, or between a pair of images. In terms of pixels, closeness between ROIs can be assessed in light of the traditional closeness between points and sets and closeness between sets using topology or proximity theory. A metric free nearness measure is introduced in this paper by finding common patterns among disjoint description based neighbourhoods obtained from these spatially defined sets. The contribution of this article is a metric free nearness measure implemented within the Proximity System, an application used to demonstrate near set concepts using digital images.https://link.springer.com/article/10.1007/s11786-013-0141-
A computational discussion on brain topodynamics: Comment on "Topodynamics of metastable brains" by Arturo Tozzi et al.
Preprint version.https://www.sciencedirect.com/science/article/pii/S157106451730062
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