The shear modulus of the human vocal fold in a transverse direction

The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, such that the data can be related to direction of applied stress and anatomical context. Dynamic spring rate data were collected using a modified linear skin rheometer using human hemilarynges, and converted to estimated shear modulus via application of a simple shear model. The measurement probe was attached to the epithelial layer of the vocal fold cover using suction. A sinusoidal force of 3g was applied to the epithelium, and the resultant displacement logged at a rate of 1kHz. Force measurement accuracy was 20microg and position measurement accuracy was 4microm. The force was applied in a transverse direction at the midmembranous point between the vocal process and the anterior commissure. The shear modulus of the three female vocal folds ranged from 814 to 1232Pa. The shear modulus of the three male vocal folds ranged from 1021 to 1796Pa. These data demonstrate that it is possible to obtain estimates for the shear modulus of the vocal fold while preserving anatomical context. The modulus values reported here are higher than those reported using parallel plate rheometry. This is to be expected as the tissue is attached to surrounding structures, and is under natural tension.     

Elastic,thermodynamic, electronic,and optical properties of recently discovered superconducting transition metal boride NbRuB:An ab-initio investigation

The elastic, thermodynamic, electronic, and optical properties of recently discovered and potentially technologically important transition metal boride NbRuB, are investigated using the density functional formalism. Both generalized gradient approximation(GGA) and local density approximation(LDA) are used for optimizing the geometry and for estimating various elastic moduli and constants. The optical properties of NbRuB are studied for the first time with different photon polarizations. The frequency(energy) dependence of various optical constants complement quite well the essential features of the electronic band structure calculations. Debye temperature of NbRuB is estimated from the thermodynamical study. All these theoretical estimates are compared with published results, where available, and discussed in detail. Both electronic band structure and optical conductivity reveal robust metallic characteristics. The NbRuB possesses significant elastic anisotropy. Electronic features, on the other hand, are almost isotropic in nature. The effects of electronic band structure and Debye temperature on the emergence of superconductivity are also analyzed.     

Spherically symmetric inhomogeneous dust collapse in higher dimensional space-time and cosmic censorship hypothesis

We consider a collapsing spherically symmetric inhomogeneous dust cloud in higher dimensional space-time. We show that the central singularity of collapse can be a strong curvature or a weak curvature naked singularity depending on the initial density distribution.     

Effects of Zn on the grain boundary properties of La2−xSrxCu1−yZnyO4 superconductors

The properties of the grain boundaries (GBs) are of significant importance in high-T_c cuprates. Most large scale applications of cuprate superconductors involve usage of sintered compounds. The critical current density and the ability to trap high magnetic flux inside the sample depend largely on the quality of the GBs. Zn has the ability to pin vortices but it also degrades superconductivity. In this study we have investigated the effect of Zn impurity on the intergrain coupling properties in high-quality La_2−xSr_xCu_1−yZn_yO₄ sintered samples with different hole concentrations, p (≡x), over a wide range of Zn contents (y) using field-dependent AC susceptibility (ACS) measurements. The ACS results enabled us to determine the superconducting transition temperature T_c, and the temperature T_gcp, at which the randomly oriented superconducting grains become coupled as a function of hole and disorder contents. We have analyzed the behavior of the GBs from the systematic evolution of the values of T_gcp(p, y), T_c(p, y), and from the contribution to the field-dependent ACS signal coming from the intergrain shielding current. Zn suppresses both T_c and T_gcp in a similar fashion. The hole content and the carrier localization due to Zn substitution seem to have significant effect on the coupling properties of the GBs. We have discussed the possible implications of these findings in detail in this article.     

Kinetics and Mechanism of Oxidation of 1-Phenylsemicarbazide by Peroxydisulphate

Kinetics of oxidation of 1-phenylsemicarbazide (PSC) by peroxydisulphate ion (PDS) have been carried out where by the pseudo first order condition was verified at large excess of PDS concentration. The rate of the reaction was followed spectrophotometrically, The stoichiometry was found to be 1:1 where 1-phenylazoformamide is the oxidation product. The effect of acidity on the rate of oxidation was investigated for different temperatures. The parameters of activation ΔG*, ΔH* and ΔS* were computed for both hydrogen ion depedent and hydrogen ion independent reaction pathes. A free radical mechanism was proposed.     

Estimation of Mean and Covariance Operator for Banach Space Valued Autoregressive Processes with Dependent Innovations

In this paper we study autoregressive processes of order 1 with values in a separable Banach space it B. Such ARB(1)-processes are defined by the recursion equation

Complete and incomplete fusion in reactions of 7Li + 56Fe at E(7Li) = 50 and 68 MeV from analysis of recoil range and light-particle measurements

Excitation functions for the production of eight radioactive products of the reactions of ⁷Li on ⁵⁶Fe have been measured up to E(⁷ Li) = 89 MeV. Recoil range distributions for these products, together with inclusive proton, deuteron, triton and alpha spectra, have been measured at energies of 50 and 68 MeV. The α, t and d spectra show characteristic “break-up” components at forward angles, while the recoil distributions show evidence of complete fusion and incomplete-fusion process ⁵⁶Fe( ⁷Li,α) ⁵⁹Co ^* . A parallel study on ⁵⁵Mn shows some evidences of the ( ⁷Li,t) incomplete-fusion process, but the cross-section for this process is significantly less than for the triton fusion process. The recoil distributions can be reproduced on the assumption that essentially all the observed break-up fragments are in fact associated with incomplete fusion, but uncertainties in normalisation leave open the possibility of a significant contribution of pure break-up. A diffraction model of the ( ⁷Li,α) transfer process reproduces the observed break-up α spectra with some success. Received: 29 March 2001 / Accepted: 12 November 2001     

Field-dependent resistive transitions in YBa_2Cu_3O_(7-δ) thin films:Influence of the pseudogap on vortex dynamics

The nature of resistive transition of high-quality crystalline thin films of YBa2Cu3O7-δhas been studied under magnetic fields(H)applied along the c direction over a wide range of doped holes,p,in the Cu O2planes.The field-and temperature-dependent in-plane resistivity,ρab(T,H),has been analyzed within the thermally assisted flux-flow(TAFF)formalism.The flux activation energy,U(T,H),has been extracted from this analysis.The low-T part of theρab(T,H)data can be described by an activation energy having the functional form of U(T,H)=(1-t)m(H-0/H)β,where t=T/Tc(reduced temperature),and H0is a field scale that primarily determines the magnitude of U(T,H).The temperature exponent,m,shows a systematic variation with p,whereas the field exponent,β,is insensitive to the p values and is close to unity.The H0,on the other hand,changes rapidly as p is varied.U(T,H)is linked to the pinning potential and consequently on the superconducting condensation energy.Since the normal state pseudogap directly affects superconducting condensation energy,a clear correspondence between H0and the PG energy scale,εg,is found.Possible implications of these results are discussed.     

Oxygen isotope effect in disordered underdoped and overdoped La2−xSrxCu1−yZnyO4 superconductors

The effect of oxygen isotopic substitution on the superconducting transition temperature has been studied for heavily underdoped and overdoped La_2?xSr_xCu_1?yZn_yO₄ compounds with different Zn contents in the CuO₂ plane. The effect of Zn on the isotope coefficient, α, was significantly more pronounced in the case of the underdoped (x = 0.09) compounds compared to the overdoped (x = 0.22) ones. The variation of α with disorder content can be described quite well within a model based solely on Cooper pair-breaking in the case of the underdoped compounds. This model fails to describe the behavior of α(y) for the overdoped samples, even though Zn still suppresses T_c very effectively at this hole (Sr) content, indicating that the Zn induced pair-breaking is still very much at play. We discuss the implications of these findings in details by considering the Zn induced magnetism, stripe correlations, and possible changes in the superconducting order parameter as hole content in the CuO₂ plane, p (≡x), is varied.     

Equivalent moduli of continuity, Bloch’s theorem for pluriharmonic mappings in \mathbb{B}{\kern-8pt}\mathbb{B}^{\boldsymbol n}

In this paper, we first establish a Schwarz?CPick type theorem for pluriharmonic mappings and then we apply it to discuss the equivalent norms on Lipschitz-type spaces. Finally, we obtain several Landau??s and Bloch??s type theorems for pluriharmonic mappings.