Electrical conductivity,thermoelectric power and dielectric constant of a Gd2Ti2O7 single crystal

Electrical conductivity, thermoelectric power and dielectric constant of a Gd₂Ti₂O₇ single crystal have been studied in the temperature range 300–1000 K. Gd₂Ti₂O₇ is found to be an-type semiconductor with energy band gap 1.5 eV. It exhibits an extrinsic nature up to 675 K and an intrinsic nature above 675 K. The thermoelectric power increases with temperature in the region 300–675 K whereas it decreases with temperature in the region 675–1000 K. The dielectric constant increases slowly in the temperature range 300–675 K but this increase becomes fast in the temperature range 675–1000 K.     

The effect of the external magnetic field on the current-voltage characteristic of HTS Josephson junction arrays

The role of the external magnetic field in performance specialty of the high-temperature superconducting (HTS) Josephson junction array (JJA): HTS YBa₂Cu₃O_7−0.05 bicrystal JJA with 180 junctions, is considered. The junctions are created on the yttrium-stabilized zirconium (fianite) substrate with the bicrystal grain boundary. The experimental confirmation of the current density changes under the influence of the external DC magnetic field is obtained. The dependence of current density on the penetrated magnetic field is investigated. The optimal shielding factor needed to obtain high supercurrents in considered system is determined.     

Effects of Clinorotation on Growth and Chlorophyll Content of Rice Seeds

Microgravity, as a different environment, has been shown to affect plant growth and development (Sievers et al. 1996; Sack 1997). In the present study, effects of slow clinorotation (2 rpm) on growth and chlorophyll content in rice (variety: PRH-10) seedlings were investigated. Rice seeds were clinorotated continuously for 3, 5 and 7 days under ambient conditions. Root and shoot lengths and weights of rice seedlings were measured on the third, fifth and seventh day. Chlorophyll was extracted using N, N-Dimethylformamide (DMF). Absorption and fluorescence spectra of chlorophyll were recorded. Chlorophyll a, chlorophyll b and total chlorophyll contents were calculated from absorption spectra using Arnon’s method. Results showed an increase in root and shoot lengths in clinorotated samples. Similar results were obtained for root and shoot weights. Absorption spectra of chlorophyll showed no shift in the absorption peaks. Chlorophyll content was increased in clinorotated samples as compared to the controls. Interestingly, the difference between chlorophyll content in control and clinorotated samples decreased as the number of days of clinorotation increased. Chlorophyll a/b ratio was lowered in clinorotated samples as compared to the controls. These results suggest that slow clinorotation (2 rpm) affects plant growth and chlorophyll content in rice seedlings.     

Variance of least squares estimators for a damped sinusoidalprocess

The variance of least squares estimators for the parameter estimation of a damped sinusoidal process is analyzed, based on first-order perturbation. Analytical expressions for the variances of the frequency, damping factor, amplitude, and phase estimators are derived. Explicit expressions are given for both damped and undamped single-mode cases. The effect of mode separation on the accuracy is investigated through the two-mode case. The dependence of the variances on number of data points, model order, signal-to-noise ratio, and mode separation is investigated, both analytically and numerically, for practical applications. Extensive Monte Carlo simulation results are given to verify, enhance, and illustrate the analytical expressions     

Polyadenylation of stable RNA precursors in vivo

Polyadenylation at the 3' terminus has long been considered a specific feature of mRNA and a few other unstable RNA species. Here we show that stable RNAs in Escherichia coli can be polyadenylated as well. RNA molecules with poly(A) tails are the major products that accumulate for essentially all stable RNA precursors when RNA maturation is slowed because of the absence of processing exoribonucleases; poly(A) tails vary from one to seven residues in length. The polyadenylation process depends on the presence of poly(A) polymerase I. A stochastic competition between the exoribonucleases and poly(A) polymerase is proposed to explain the accumulation of polyadenylated RNAs. These data indicate that polyadenylation is not unique to mRNA, and its widespread occurrence suggests that it serves a more general function in RNA metabolism.     

Primary pulmonary plasmacytoma

BACKGROUND: A patient was diagnosed with an extramedullary plasmacytoma of the lung after complete resection of the mass at thoracotomy. Immunoperoxidase staining of the mass revealed monoclonal lambda chains. Screening for multiple myeloma identified a small amount of M-protein in the blood, but no other evidence of multiple myeloma was found. METHODS: A literature search was conducted to determine the prognosis and the best way to manage the patient. RESULTS: Nineteen cases of primary pulmonary plasmacytoma were found in the literature. The age range was 3-79 years. Most of these cases were diagnosed at thoracotomy and treated by surgical excision. Immunohistochemical evaluation of the lesion is essential for diagnosis but was done in only three cases. CONCLUSIONS: Surgery and radiation therapy seem to be equally effective forms of treatment. The role of adjuvant chemotherapy is unknown. Local recurrences are rare. Follow-up data were inadequate to determine disease-free survival, progression to multiple myeloma, and overall survival in primary pulmonary plasmacytoma. Close follow-up is needed to detect progression.     

An extension of the graph theoretical approach to predict the secondary structure of large RNAs: the complex of 16S and 23S rRNAs from E. coli as a case study

An algorithm using the graph theoretical approach to predict secondary structures of large nucleic acids is discussed. Reliability of prediction can be improved by incorporating available experimental data and sequence homology information. As a case study, this algorithm is applied to predict the secondary structure of the 16S-23S rRNA complex from E. coli. It was found that several structures of the complex can coexist. The computer program developed to predict the secondary structure of large RNAs can be run on IBM PC/AT compatible systems.