Subharmonic solutions for nonautonomous sublinear second order Hamiltonian systems

AbstractSome existence theorems are obtained for subharmonic solutions of nonautonomous second order Hamiltonian systems by the minimax methods in critical point theory

Periodic Solutions of a Class of Non-autonomous Second-Order Systems

AbstractSome existence theorems are obtained by the least action principle for periodic solutions of nonautonomous second-order systems with a potential which is the sum of a subconvex function and a subquadratic function

DYNAMICAL EFFECTS OF SPRINT START ON DIFFERENT STARTING BLOCKS

The purpose of this study was to examine the dynamical variables of sprint start in two different starting blocks setups. The ReacTime Personal Systems was used to record the Reaction Time (RT) and the Power of 20 teenaged sprinters (15 males and 5 females) in the sprint start. In addition, the Newtest Powertimer photocells were used to collect subjects’ 0 to 10 metre (T10) performance after the sprint start. The variables were tested by the repeated measures one-way ANOVA by SPSS 19.0 statistical software at a .05 significant level. The results showed that there were better effects on the short starting block (SB) in power generation performance than the long starting block (LB). The athletes can apply short starting block and make adjustments and modifications based on their training conditions

Homoclinic orbits for a class of second-order Hamiltonian systems with concave–convex nonlinearities

In this paper, we study the existence of multiple homoclinic solutions for the following second order Hamiltonian systems \begin{equation*} \ddot{u}(t)-L(t)u(t)+\nabla W(t,u(t))=0, \end{equation*} where $L(t)$ satisfies a boundedness assumption which is different from the coercive condition and $W$ is a combination of subquadratic and superquadratic terms

Decrease in inner retinal thickness at para- and perifoveal areas before vascular retinopathy in patients with metabolic risk factors

AbstractBackgroundHypertension, dyslipidemia, and hyperglycemia are major risk factors for vascular retinopathy. The relationship between retinal thickness at the macular area and metabolic risk factors, as well as visual impairment, in elderly patients before developing vascular occlusion needs to be investigated.MethodsIn this prospective, case-control study, patients >60 years old, without objective visual threatened ocular diseases or systemic abnormalities, except for hypertension, dyslipidemia or/and hyperglycemia, were included for measurement of retinal thickness at the macular area by optical coherence tomography (OCT).ResultsFifty-four patients were analyzed; 11 patients had no metabolic risk factors, 16 had one, 17 had two, and 10 had three. There was no significant difference in age, and full and outer retinal thickness, but there was a significantly lower inner retinal thickness at the parafoveal (p = 0.0013) and perifoveal (p = 0.018) areas in patients with at least one metabolic risk factor. The superior (p = 0.040) and inferior (p = 0.046) inner retina at the perifovea and superior (p = 0.013) inner retinal thickness at the parafovea were sensitive to metabolic abnormalities. Only patients with three factors had significantly reduced best corrected visual acuity (BCVA).ConclusionElderly patients with metabolic risk factors had decreased inner retinal thickness at the para- and perifoveal areas before retinal vascular diseases. Accelerated inner retinal degeneration occurred prior to visual impairment

Enhanced sensing of optomechanically induced nonlinearity by linewidth suppression and optical bistability in cavity-waveguide systems

We study enhanced sensing of optomechanically induced nonlinearity (OMIN) in a cavity-waveguide coupled system. The Hamiltonian of the system is anti-PT symmetric with the two involved cavities being dissipatively coupled via the waveguide. When a weak waveguide-mediated coherent coupling is introduced, the anti-PT symmetry may break down. However, we find a strong bistable response of the cavity intensity to the OMIN near the cavity resonance, benefiting from linewidth suppression caused by the vacuum induced coherence. The joint effect of optical bistability and the linewidth suppression is inaccessible by the anti-PT symmetric system involving only dissipative coupling. Due to that, the sensitivity is greatly enhanced by two orders of magnitude compared to that for the anti-PT symmetric model. Moreover, the sensitivity shows resistances to a reasonably large cavity decay and robustness to fluctuations in the cavity-waveguide detuning. Based on the integrated optomechanical cavity-waveguide systems, the scheme can be used for sensing different physical quantities related to the single-photon coupling strength, and has potential applications in high-precision measurements with physical systems involving Kerr-type nonlinearity.Comment: 9 pages, 5 figure

THE INFLUENCE OF ADJUSTABLE PUTTER HEAD WEIGHTING ON THE STROKE

The purpose of this study was to investigate the effects of putter head weighting towards the heel and the toe on the kinematic aspects of the putting stroke. Seven (n=7) male golfers (age 42.6 ±2.3 y) with high proficiency (handicap 9.5 ±1.4) were recruited for this study. The experiment was carried out in an indoor studio with artificial grass (Stimp 10). Two toe weight and two heel weight settings were tested and compared with the standard weighting. Results suggest that putter head weighing influences the characteristics of the putting stroke, and systematic differences were found between toe and heel weighting. It is concluded that fitting the weight and the balance of a putter head is critical for supporting each individual's stroke and putting performance