Comparison of Pitching from Flat Ground vs. 10-Inch Mound Regarding Elbow Varus Torque and Arm Speed

Purpose: The purpose of this study was to examine the effect of throwing surface and distance on varus elbow torque and arm speed. Methods: 11 male collegiate baseball pitchers (age = 20.73 ± 1.56 years, height = 175.26 ± 9.03 cm, mass = 70.31 ± 9.03 kg) participated in this study. Varus elbow torque and distance were measured using a 3D motion sensor housed in a spandex sleeve at the medial joint line of the elbow. Participants were instructed to complete their normal warmup routine as if they were about to pitch in a bullpen session or a game. Participants were then fitted with the sleeve and 3D motion sensor and then instructed to throw 5 maximum effort fastballs at both 60 feet 6 inches and 50 feet 6 inches from a 10-inch mound and 5 maximum effort fastballs at both 60 feet 6 inches and 50 feet 6 inches from flat ground. A two-way ANOVA with repeated measures was used to analyze the differences in elbow varus torque and arm speed when pitching from 60 feet 6 inches and 50 feet 6 inches from a 10-inch mound and from flat ground. Tests of significance were carried out at an alpha level p \u3c 0.05. Results: Significant differences in elbow varus torque were found when throwing from a 10-inch mound compared to flat ground (10-inch mound = 46.99 ± 2.36, Flat ground = 42.67 ± 3.14). No significant differences in elbow varus torque were found when throwing from 60 feet 6 inches compared to 50 feet 6 inches regardless of surface (60 feet 6 inches = 45.38 ± 2.96, 50 feet 6 inches = 44.28 ± 2.59). No significant differences in arm speed were found regardless of surface or distance. Conclusions: Throwing from a 10-inch mound appears to place more torque on the elbow than throwing from flat ground. Clinicians should be mindful of this fact when progressing patients through throwing programs

Spectroscopy of Nine Cataclysmic Variable Stars

We present optical spectroscopy of nine cataclysmic binary stars, mostly dwarf novae, obtained primarily to determine orbital periods Porb. The stars and their periods are LX And, 0.1509743(5) d; CZ Aql, 0.2005(6) d; LU Cam, 0.1499686(4) d; GZ Cnc, 0.0881(4) d; V632 Cyg, 0.06377(8) d; V1006 Cyg, 0.09903(9) d; BF Eri, 0.2708804(4) d; BI Ori, 0.1915(5) d; and FO Per, for which Porb is either 0.1467(4) or 0.1719(5) d. Several of the stars proved to be especially interesting. In BF Eri, we detect the absorption spectrum of a secondary star of spectral type K3 +- 1 subclass, which leads to a distance estimate of approximately 1 kpc. However, BF Eri has a large proper motion (100 mas/yr), and we have a preliminary parallax measurement that confirms the large proper motion and yields only an upper limit for the parallax. BF Eri's space velocity is evidently large, and it appears to belong to the halo population. In CZ Aql, the emission lines have strong wings that move with large velocity amplitude, suggesting a magnetically-channeled accretion flow. The orbital period of V1006 Cyg places it squarely within the 2- to 3-hour "gap" in the distribution of cataclysmic binary orbital periods.Comment: 31 pages, 5 postscript and one PNG figure. Accepted for PAS

Compression modulus of macroscopic fiber bundles

We study dense, disordered stacks of elastic macroscopic fibers. These stacks often exhibit non-linear elasticity, due to the coupling between the applied stress and the internal distribution of fiber contacts. We propose a theoretical model for the compression modulus of such systems, and illustrate our method by studying the conical shapes frequently observed at the extremities of ropes and other fiber structures. studying the conical shapes frequently observed at theextremities of ropes and other fiber structures

Spatially Bandgap-Graded MoS₂₍₁-ₓ₎Se₂ₓ Homojunctions for Self-Powered Visible–Near-Infrared Phototransistors

Ternary transition metal dichalcogenide alloys with spatially graded bandgaps are an emerging class of two-dimensional materials with unique features, which opens up new potential for device applications. Here, visible–near-infrared and self-powered phototransistors based on spatially bandgap-graded MoS2(1−x)Se2x alloys, synthesized by a simple and controllable chemical solution deposition method, are reported. The graded bandgaps, arising from the spatial grading of Se composition and thickness within a single domain, are tuned from 1.83 to 1.73 eV, leading to the formation of a homojunction with a built-in electric field. Consequently, a strong and sensitive gate-modulated photovoltaic effect is demonstrated, enabling the homojunction phototransistors at zero bias to deliver a photoresponsivity of 311 mA W−1, a specific detectivity up to ~ 1011 Jones, and an on/off ratio up to ~ 104. Remarkably, when illuminated by the lights ranging from 405 to 808 nm, the biased devices yield a champion photoresponsivity of 191.5 A W−1, a specific detectivity up to ~ 1012 Jones, a photoconductive gain of 106–107, and a photoresponsive time in the order of ~ 50 ms. These results provide a simple and competitive solution to the bandgap engineering of two-dimensional materials for device applications without the need for p–n junctions

Increased Atmospheric Ammonia over the World's Major Agricultural Areas Detected from Space

This study provides evidence of substantial increases in atmospheric ammonia (NH3) concentrations (14-year) over several of the worlds major agricultural regions, using recently available retrievals from the Atmospheric Infrared Sounder (AIRS) aboard NASA's Aqua satellite. The main sources of atmospheric NH3 are farming and animal husbandry involving reactive nitrogen ultimately derived from fertilizer use; rates of emission are also sensitive to climate change. Significant increasing trends are seen over the U.S. (2.61%per yr), the European Union (EU) (1.83%per yr), and China (2.27%per yr). Over the EU, the trend results from decreased scavenging by acid aerosols. Over the U.S., the increase results from a combination of decreased chemical loss and increased soil temperatures. Over China, decreased chemical loss, increasing temperatures, and increased fertilizer use all play a role. Over South Asia, increased NH3 emissions are masked by increased SO2 and NOX emissions, leading to increased aerosol loading and adverse health effects

Managing China's energy sector: between the market and the state

As China has now become the largest energy consumer in the world, its energy sector has understandably huge domestic and global implications. In this Special Issue, which is an interdisciplinary one, comprising a set of eight in-depth empirical studies by leading international experts in the field, we set out to examine the management of the transformation of China's conventional and renewable energy sectors, with special attention to state–business relations and their link to the market

The Simplicial Ricci Tensor

The Ricci tensor (Ric) is fundamental to Einstein's geometric theory of gravitation. The 3-dimensional Ric of a spacelike surface vanishes at the moment of time symmetry for vacuum spacetimes. The 4-dimensional Ric is the Einstein tensor for such spacetimes. More recently the Ric was used by Hamilton to define a non-linear, diffusive Ricci flow (RF) that was fundamental to Perelman's proof of the Poincare conjecture. Analytic applications of RF can be found in many fields including general relativity and mathematics. Numerically it has been applied broadly to communication networks, medical physics, computer design and more. In this paper, we use Regge calculus (RC) to provide the first geometric discretization of the Ric. This result is fundamental for higher-dimensional generalizations of discrete RF. We construct this tensor on both the simplicial lattice and its dual and prove their equivalence. We show that the Ric is an edge-based weighted average of deficit divided by an edge-based weighted average of dual area -- an expression similar to the vertex-based weighted average of the scalar curvature reported recently. We use this Ric in a third and independent geometric derivation of the RC Einstein tensor in arbitrary dimension.Comment: 19 pages, 2 figure

Slow stress relaxation in randomly disordered nematic elastomers and gels

Randomly disordered (polydomain) liquid crystalline elastomers align under stress. We study the dynamics of stress relaxation before, during and after the Polydomain-Monodomain transition. The results for different materials show the universal ultra-slow logarithmic behaviour, especially pronounced in the region of the transition. The data is approximated very well by an equation Sigma(t) ~ Sigma_{eq} + A/(1+ Alpha Log[t]). We propose a theoretical model based on the concept of cooperative mechanical resistance for the re-orientation of each domain, attempting to follow the soft-deformation pathway. The exact model solution can be approximated by compact analytical expressions valid at short and at long times of relaxation, with two model parameters determined from the data.Comment: 4 pages (two-column), 5 EPS figures (included via epsfig

X-Ray Standing-Wave Investigations of Valence Electronic Structure

We have examined the valence-electron emission from Cu, Ge, GaAs, InP, and NiO single crystals under the condition of strong x-ray Bragg reflection; i.e., in the presence of the spatially modulated x-ray standing-wave interference field that is produced by the superposition of the incident and reflected x-ray beams. These crystals span the entire metallic, covalent, and ionic range of solid-state bonding. It is demonstrated that the valenceelectron emission is closely coupled to the atomic cores, even for electron states close to a metallic Fermi edge. Using the bond-orbital approximation, the x-ray standing-wave structure factor for valence-electron emission is derived in terms of the bond polarities and photoionization cross sections of the atoms within the crystalline unit cell and compared to experiment. Additionally, we demonstrated that by exploiting the spatial dependence of the electric-field intensity under Bragg condition, site specific valence electronic structure may be obtained. The technique is demonstrated for GaAs and NiO

Hodge Theory on Metric Spaces

Hodge theory is a beautiful synthesis of geometry, topology, and analysis, which has been developed in the setting of Riemannian manifolds. On the other hand, spaces of images, which are important in the mathematical foundations of vision and pattern recognition, do not fit this framework. This motivates us to develop a version of Hodge theory on metric spaces with a probability measure. We believe that this constitutes a step towards understanding the geometry of vision. The appendix by Anthony Baker provides a separable, compact metric space with infinite dimensional \alpha-scale homology.Comment: appendix by Anthony W. Baker, 48 pages, AMS-LaTeX. v2: final version, to appear in Foundations of Computational Mathematics. Minor changes and addition