Toward an analytic determination of the deconfinement temperature in SU(2) L.G.T.

We consider the SU(2) lattice gauge theory at finite temperature in (d+1) dimensions, with different couplings $\beta_t$ and $\beta_s$ for timelike and spacelike plaquettes. By using the character expansion of the Wilson action and performing the integrals over space-like link variables, we find an effective action for the Polyakov loops which is exact to all orders in $\beta_t$ and to the first non-trivial order in $\beta_s$. The critical coupling for the deconfinement transition is determined in the (3+1) dimensional case, by the mean field method, for different values of the lattice size $N_t$ in the compactified time direction and of the asymmetry parameter $\rho = \sqrt{\beta_t/\beta_s}$. We find good agreement with Montecarlo simulations in the range $1\leq N_t \leq 5$, and good qualitative agreement in the same range with the logarithmic scaling law of QCD. Moreover the dependence of the results from the parameter $\rho$ is in excellent agreement with previous theoretical predictions.Comment: uuencoded latex file of 32 pages plus 3 ps figure

Neurodegenerative Properties of Chronic Pain: Cognitive Decline in Patients with Chronic Pancreatitis

Chronic pain has been associated with impaired cognitive function. We examined cognitive performance in patients with severe chronic pancreatitis pain. We explored the following factors for their contribution to observed cognitive deficits: pain duration, comorbidity (depression, sleep disturbance), use of opioids, and premorbid alcohol abuse. The cognitive profiles of 16 patients with severe pain due to chronic pancreatitis were determined using an extensive neuropsychological test battery. Data from three cognitive domains (psychomotor performance, memory, executive functions) were compared to data from healthy controls matched for age, gender and education. Multivariate multilevel analysis of the data showed decreased test scores in patients with chronic pancreatitis pain in different cognitive domains. Psychomotor performance and executive functions showed the most prominent decline. Interestingly, pain duration appeared to be the strongest predictor for observed cognitive decline. Depressive symptoms, sleep disturbance, opioid use and history of alcohol abuse provided additional explanations for the observed cognitive decline in some of the tests, but to a lesser extent than pain duration. The negative effect of pain duration on cognitive performance is compatible with the theory of neurodegenerative properties of chronic pain. Therefore, early and effective therapeutic interventions might reduce or prevent decline in cognitive performance, thereby improving outcomes and quality of life in these patients

Effect of annealing temperature on the structural and magnetic properties of Ba-Pb-hexaferrite powders synthesized by sol-gel auto-combustion method

The annealing temperature (T-a) dependent development in phase purity, morphology and magnetic properties of BaxPb1-xFe12O19 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) powders synthesized via sol-gel auto-combustion route were studied. The hexagonal phase of PbFe12O19 forms directly via solid-state-reaction between alpha-Fe2O3 and PbO during annealing of the combustion product at T-a similar to 900 degrees C, but the BaFe12O9 phase forms at T-a similar to 1200 degrees C through the formation of BaFe2O4 and alpha-Fe2O3 as intermediate-phases at low T-a. The BaxPb1-xFe12O19-phase purity of the samples depend on T-a. For T-a > 1000 degrees C, PbO evaporates from Pb-containing samples. With increasing T-a, growth of hexagonal-shaped sharp-edged particles was observed for Barium-rich samples, however, the sharp-edges dissolute for Lead-rich samples. High saturation magnetization was observed for Ba-rich samples annealed at 1100 degrees C. For all the studied samples, magnetic coercivity increases with x but decreases with T-a. The magnetic properties were correlated with the structure, microstructure and grain-size of the samples

Dual-scale rough multifunctional superhydrophobic ITO coatings prepared by air annealing of sputtered indium tin alloy thin films

A novel method to fabricate multifunctional indium tin oxide (ITO) coatings is discussed. Superhydrophobic ITO coatings are fabricated by radio frequency balanced magnetron sputter deposition of indium–tin alloy on glass substrates followed by complete oxidation of the samples in air. The chemical nature and structure of the coatings are verified by X-ray diffraction, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. Field emission scanning electron microscopic studies of the coatings display rod-like and blob-like microstructures, together with fractal-like nanostructures infused on top. Microscale roughness of the ITO coatings is measured by three-dimensional profilometry and is found to be in the range of 0.1–3 μm. Thus the presence of micro- and nano- sized structures result in dual-scale roughness. The variation in the contact angle with the deposition time is studied using a contact angle goniometer. High water contact angles (>160°) and low contact angle hysteresis (5°) are obtained at an optimum microscale roughness. The ITO coatings also exhibit other functional properties, such as low sheet resistance and semi-transparent behaviour in the visible region. The loss in the transparency of the ITO coatings is attributed to the presence of higher scale of roughness. The photoluminescence measurements show large photoemission in the visible region. It is expected that further improvements in the multifunctional properties of transparent conducting oxides will open new frontiers in designing novel materials with exotic properties

Steady-shear response of magnetorheological fluid containing coral-shaped yttrium-iron-garnet particles

The steady-state magneto-mechanical response of a magnetorheological fluid (MRF), prepared by dispersing 40 wt % of magnetically soft, light-weight coral-network-shaped yttrium iron garnet (YIG; Y3Fe5O12) powder in silicone oil (140 cSt) is studied as a function of shear rate, under different applied magnetic fields (B). The results show that the yield strength (tau(Y)) and viscosity (eta) of the MRF increase with B, and are strongly influenced by the physical parameters of the particles such as morphology and saturation magnetization. The low density of the YIG-particles, leading to higher volume fraction for equal mass loading, results in a higher viscosity in the absence of a magnetic field, in comparison to that of conventional metallic Fe-particle-based MRFs. Due to this, there is a relatively smaller increase in tau(Y) and eta when the magnetic field is switched on. The YIG-particles-based MRF has the advantages of high chemical stability, thermo-oxidative resistance and low-cost

Cation distributions and magnetism of Al-substituted CoFe2O4 - NiFe2O4 solid solutions synthesized by sol-gel auto-combustion method

Aluminium substituted cobalt-nickel ferrite nanoparticles were synthesized by citrate gel auto-combustion method followed by annealing at 1000 degrees C for 1 h in air. Scanning electron micrographs of all the samples show crystalline particles of irregular morphology with a small variation in particle sizes (similar to 110-160 nm). From the analysis of the X-ray diffraction results we observed that the unit cell parameter decreases linearly with increase in aluminium concentration due to the smaller ionic radius of the Al3+ ions substituting the other cations such as Co2+, Ni2+ and Fe3+ ions in the compounds. The room temperature Mossbauer spectra of the samples show Zeeman split sextet patterns corresponding to the tetrahedral (Th) and octahedral (Oh) interstitial iron (Fe3+) cations. The observed magnetic hyperfine field (B-hf) decreases with increase in Al-concentration due to the distribution of diamagnetic Al3+ in the environment of Fe-57 probe atoms. The saturation magnetization measured by Vibrating Sample Magnetometer (VSM) shows a similar trend like that of Bhf. The distributions of the cations obtained from the Rietveld refinement and Mossbauer spectroscopy results indicate an increase in Fe3+(Th)/Fe3+ (Oh) occupancy-ratio on increasing Al3+ concentration, and Ni-2 cations prefer the octahedral site, whereas Co-2 and Al3+ ions redistribute themselves in tetrahedral and octahedral sites, in the ratio 2:3

Effect of Coral-Shaped Yttrium Iron Garnet Particles on the EMI Shielding Behaviour of Yttrium Iron Garnet-Polyaniline-Wax Composites

We report the physicochemical insight into the role of coral-shaped yttrium-iron-garnet (YIG) particles for high electromagnetic interference (EMI) shielding behaviour of YIG-polyaniline (PANI)-Wax composites. We studied the total shielding effectiveness (SET) of various compositions of the composites in X and K-u-band frequencies (8-18 GHz) and came upon with a critical concentration (20 wt% of YIG) for which SET is maximum (-44.8 dB). At this critical concentration, the coral shape of YIG helps in effectively increasing the YIG-PANI interfaces necessary for the multiple scattering of electromagnetic (EM) waves. The scattered microwave is then trapped within the dense coral-network of YIG until they are absorbed therein by PANI via conduction loss; thereby, dramatically enhancing the microwave attenuation. The detailed EMI shielding mechanism is explained based on electrical and magnetic properties of the composites. Our result demonstrates the importance of morphology of the dielectric/magnetic particles and their concentration in the composites for designing an efficient EMI shield