Temperature dependence of the i.r. optical properties of LiF1

Essentially distortion-free imaginary dielectric index spectra have been obtained for LiF from Kramers-Kronig (KK) dispersion analysis of I.R. reflectance data at 300 K, 80 K and 20 K. The frequency dependence of the damping function as well as the temperature dependence of the various dispersion parameters of the first transverse optic mode have been illustrated. The effective damping constant $\text{}\text{?}$gg_o, and the resonance frequency ν_o, are found to be in satisfactory agreement with the theoretical calculations.     

Evaluation of the Mn Lα and Lβ Spectra of Mn Metal and of Various Mn-Oxides

The Mn Lα and Lβ spectra of Mn, MnO, Mn₃O₄, Mn₂O₃, and MnO₂ have been measured. Each Mn La spectrum has been deconvoluted into two bands, Lα_A and Lα_B, and the integrated Lα_A/Lα_B intensity ratio was found to be inversely proportional to the Mn-0 inter-atomic distance, but proportional to the oxidation number. This finding tends to indicate the likelihood of crossover transition from oxygen to manganese. The intensity ratio Lβ/Lα_B of the pure metal was found to coincide closely with the statistically predicted value of 0.5. Furthermore, for Mn-metal, as well as for the oxides, the shift of the Lα_A band from the Lα_B band was found to agree with the change in the Lβ/Lα peak intensity ratio as a function of oxidation number.     

Non-Gravitational Effects with Density-Matching in Evaluating the Influence of Sedimentation on Colloidal Coagulation

The method of density matching between the solid and liquid phases is often adopted to effectively eliminate the effect of sedimentation of suspensions in studies on dynamic behaviour of a colloidal system. However, the associated changes in the solvent composition may bring side effects to the properties investigated and therefore might lead to a faulty conclusion if the relevant correction is not made. To illustrate the importance of this side effect, we present an example of the sedimentation influence on the coagulation rate of suspensions of 2μm （diameter） polystyrene. The liquid mixtures, in the proper proportions of water （H2O）, deuterium oxide （D2O） and methanol （MeOH） as the liquid phase, density-matched and unmatched experiments are performed. Besides the influence of viscosity, the presence of methanol in solvent media, used to enhance the sedimentation effect, causes significant changes （reduction） in rapid coagulation rates compared to that in pure water. Without the relevant corrections for those non-gravitational factors it seems that gravitational sedimentation would retard the coagulation. The magnitude of the contribution from the non-gravitational factor is quantitatively determined, making the relevant correction possible. After necessary the influence of the sedimentation on coagulation rates at corrections for all factors, our experiments show that the initial stage of the coagulation is not observable.     

Spin squeezing and quantum correlations

We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.     

Proton magnetic resonance spectroscopic images and MRI volumetric studies for lateralization of temporal lobe epilepsy

We obtained 2D magnetic resonance (MR) spectroscopic images (MRSI) and MRI volumetric measurements (MRIV) of amygdala and hippocampus in 30 consecutive patients with temporal lobe epilepsy (TLE) being evaluated for surgical treatment. Both MRSI and MRIV lateralization showed good agreement with the current gold standard of clinical-EEG lateralization. Each exam separately correctly lateralized 25 out of 30 patients with no false lateralization. Combining both exams, lateralization could be achieved in 28 out of 30 patients. The two patients with no significant asymmetry had bitemporal EEG abnormalities, and bilateral damage on both MRIV and MRSI. There was a good correlation between the magnitude of the MRSI and MRIV asymmetry (Pearson COEFFICIENT = 0.83; p < .0001). Both MRSI and MRIV were normal in our patients with seizures originating outside the temporal lobes. Both MRIV and MRSI can lateralize TLE in 83% of patients. Combination of the two modalities allows lateralization in 93% of patients. Patients who cannot be lateralized generally have symmetrical bitemporal abnormalities; they are not incorrectly lateralized. The structural and chemical pathologic abnormalities seen in TLE seem to be associated with the seizure focus, and may be as, or even more, reliable than a few recorded seizures in predicting the side from which most seizures originate.     

A Self-Bracketing Search Technique for the Classical Dispersion Analysis of Infrared Reflectance Data

If an observed infrared reflectance band corresponds to a harmonic vibrational mode, then it is feasible by means of well known dispersion relationships to calculate reflectance values R_c for an ideal reflectance curve that agrees with the curve obtained from experimentally observed R_x values. The technique of comparing R_c with R_x has been denoted as “classical dispersion,” or CD analysis. In the obtaining of dispersion parameters, such as oscillator strength (S_j), damping constant (Y_j), and resonant frequency (v_j) through CD analysis of infrared reflectance data, a number of methods have been used.