On the validity of the method of reduction of dimensionality: area of contact, average interfacial separation and contact stiffness

It has recently been suggested that many contact mechanics problems between solids can be accurately studied by mapping the problem on an effective one dimensional (1D) elastic foundation model. Using this 1D mapping we calculate the contact area and the average interfacial separation between elastic solids with nominally flat but randomly rough surfaces. We show, by comparison to exact numerical results, that the 1D mapping method fails even qualitatively. We also calculate the normal interfacial stiffness $K$ and compare it with the result of an analytical study. We attribute the failure of the elastic foundation model to the neglect of the long-range elastic coupling between the asperity contact regions.Comment: 5 pages, 4 figures, 29 reference

QCD evolution of naive-time-reversal-odd fragmentation functions

We study QCD evolution equations of the first transverse-momentum-moment of the naive-time-reversal-odd fragmentation functions - the Collins function and the polarizing fragmentation function. We find for the Collins function case that the evolution kernel has a diagonal piece same as that for the transversity fragmentation function, while for the polarizing fragmentation function case this piece is the same as that for the unpolarized fragmentation function. Our results might have important implications in the current global analysis of spin asymmetries.Comment: 8 pages,4 figure

Evolution of twist-3 multi-parton correlation functions relevant to single transverse-spin asymmetry

We constructed two sets of twist-3 correlation functions that are responsible for generating the novel single transverse-spin asymmetry in the QCD collinear factorization approach. We derive evolution equations for these universal three-parton correlation functions. We calculate evolution kernels relevant to the gluonic pole contributions to the asymmetry at the order of $\alpha_s$. We find that all evolution kernels are infrared safe as they should be and have a lot in common to the DGLAP evolution kernels of unpolarized parton distributions. By solving the evolution equations, we explicitly demonstrate the factorization scale dependence of these twist-3 correlation functions.Comment: 28 pages, 17 figures, new materials and references adde

Effects of Aerobic Training in Adolescents with Down Syndrome

The purpose of this study was to evaluate the effects that aerobic training has on adolescents and young adults with Down syndrome. Fourteen individuals with Down syndrome (mean age = 17.7 yr) participated in a 10-wk walking/jogging exercise training study. A pre- and post-training walking treadmill test was performed to determine the following parameters: peak oxygen uptake (VO2, absolute and relative), minute ventilation (VE, l•min-1), heart rate HR, b•min-1), RER (VCO2/VO2), and time and grade to exhaustion. Following the pre-training evaluations, subjects were assigned to a control group (N = 4) or an exercise group (N= 10). The exercise group underwent a 10-wk walk/jog training program at a frequency of 3 times per week, for a duration of 30 min, and at an intensity, of approximately 65-75% peak HR. Following training, both control and experimental groups showed no changes in peak VO2 (absolute and relative), VE, HR, and RER. The exercise group, however, did demonstrate a significant improvement in peak exercise time (and grade). Although the training program did not produce improvements in aerobic capacity, it did produce gains in walking capacity. It was concluded that the adolescents and young adults may not be able to improve their aerobic capacity when performing a walk/jog training program. © 1993 by the American College of Sports Medicine

Conformal Affine Toda Soliton and Moduli of IIB Superstring on AdS5×S5AdS_5\times S^5

In this paper we interpret the hidden symmetry of the moduli space of IIB superstring on $AdS_{5}\times S^{5}$ in terms of the chiral embedding in $AdS_{5}$, which turns to be the $\mathbb{CP}^{3}$ conformal affine Toda model. We review how the position $\mu$ of poles in the Riemann-Hilbert formulation of dressing transformation and how the value of loop parameters $\mu$ in the vertex operator of affine algebra determines the moduli space of the soliton solutions, which describes the moduli space of the Green-Schwarz superstring. We show also how this affine SU(4) symmetry affinize the conformal symmetry in the twistor space, and how a soliton string corresponds to a Robinson congruence with twist and dilation spin coefficients $\mu$ of twistor.Comment: Final version, Misprints corrected, Note adde

Localization of the Grover walks on spidernets and free Meixner laws

A spidernet is a graph obtained by adding large cycles to an almost regular tree and considered as an example having intermediate properties of lattices and trees in the study of discrete-time quantum walks on graphs. We introduce the Grover walk on a spidernet and its one-dimensional reduction. We derive an integral representation of the $n$-step transition amplitude in terms of the free Meixner law which appears as the spectral distribution. As an application we determine the class of spidernets which exhibit localization. Our method is based on quantum probabilistic spectral analysis of graphs.Comment: 32 page

Spectral variations of AeBe Herbig stars in the Mon R1 association

We present the change in the Halpha emission-line profile of the spectra of some AeBe Herbig stars. In the spectrum of VY Mon, Halpha may have one of three profile types: P Cyg, P Cyg III or single line in accordance with the brightness variations of the star. HD259431 now shows a double Halpha profile with the red component stronger than the blue component, while in the earlier observations the blue peak was higher than the red peak. Finally, the last Halpha profile of LkHalpha215 is very similar to that obtained by Finkenzeller et al.Comment: 4pages, 3figure

Influence of inversion on Mg mobility and electrochemistry in spinels

Magnesium oxide and sulfide spinels have recently attracted interest as cathode and electrolyte materials for energy-dense Mg batteries, but their observed electrochemical performance depends strongly on synthesis conditions. Using first principles calculations and percolation theory, we explore the extent to which spinel inversion influences Mg$^{2+}$ ionic mobility in MgMn$_2$O$_4$ as a prototypical cathode, and MgIn$_2$S$_4$ as a potential solid electrolyte. We find that spinel inversion and the resulting changes of the local cation ordering give rise to both increased and decreased Mg$^{2+}$ migration barriers, along specific migration pathways, in the oxide as well as the sulfide. To quantify the impact of spinel inversion on macroscopic Mg$^{2+}$ transport, we determine the percolation thresholds in both MgMn$_2$O$_4$ and MgIn$_2$S$_4$. Furthermore, we analyze the impact of inversion on the electrochemical properties of the MgMn$_2$O$_4$ cathode via changes in the phase behavior, average Mg insertion voltages and extractable capacities, at varying degrees of inversion. Our results confirm that inversion is a major performance limiting factor of Mg spinels and that synthesis techniques or compositions that stabilize the well-ordered spinel structure are crucial for the success of Mg spinels in multivalent batteries

Quantum Correction in Exact Quantization Rules

An exact quantization rule for the Schr\"{o}dinger equation is presented. In the exact quantization rule, in addition to $N\pi$, there is an integral term, called the quantum correction. For the exactly solvable systems we find that the quantum correction is an invariant, independent of the number of nodes in the wave function. In those systems, the energy levels of all the bound states can be easily calculated from the exact quantization rule and the solution for the ground state, which can be obtained by solving the Riccati equation. With this new method, we re-calculate the energy levels for the one-dimensional systems with a finite square well, with the Morse potential, with the symmetric and asymmetric Rosen-Morse potentials, and with the first and the second P\"{o}schl-Teller potentials, for the harmonic oscillators both in one dimension and in three dimensions, and for the hydrogen atom.Comment: 10 pages, no figure, Revte

Alcohol consumption among tertiary students in the Hohoe municipality, Ghana: analysis of prevalence, effects, and associated factors from a cross-sectional study.

Background:Alcohol consumption constitutes a major public health problem as it has negative consequences on the health, social, psychological, and economic outcomes of individuals. Tertiary education presents students with unique challenges and some students resort to the use of alcohol in dealing with their problems. This study, therefore, sought to determine alcohol use, its effects, and associated factors among tertiary students in the Hohoe Municipaility of Ghana. Methods: An institutional-based cross-sectional study was conducted among 418 tertiary students in the Hohoe Municipality of Ghana using a two-stage sampling technique. Data were collected using structured questionnaires. A binary logistic regression modelling was used to determine the strength of the association between alcohol consumption and the explanatory variables. The level of significance was set at p < 0.05. Stata version 16.0 was used to perform the analysis. Results: The lifetime prevalence of alcohol consumption was 39.5%. Out of them, 49.1% were still using alcohol, translating to an overall prevalence of 19.4% among the tertiary students. Self-reported perceived effects attributed to alcohol consumption were loss of valuable items (60.6%), excessive vomiting (53.9%), stomach pains/upset (46.1%), accident (40.0%), unprotected sex (35.1%), risk of liver infection (16.4%), depressive feelings (27.3%), diarrhoea (24.2%), debt (15.2%), and petty theft (22.4%). In terms of factors associated with alcohol consumption, students aged 26 years and above were more likely to have consumed alcohol [AOR = 4.4, 95%CI = 1.74, 11.14] than those in 16–20 years group. Muslim students had lower odds of alcohol consumption compared to Christians [AOR = 0.1, 95% CI = 0.02, 0.31]. It was also found that students who had peer influence [AOR = 3.7, 95%CI = 2.31, 5.82] and those who had academic adjustment problems [AOR = 3.6, 95% CI = 2.01, 6.46] were more likely to consume alcohol. Conclusion: Lifetime prevalence of alcohol consumption is high among tertiary students in the Hohoe Municipality of Ghana, with several physical, psychosocial and economic consequences. Alcohol-related education should be intensified in tertiary institutions and counseling units should be equipped with relevant assessment tools to assess and help students who are at risk and those who are already consuming alcohol