Spectroscopic detection of COClF in the tropical and mid-latitude lower stratosphere

We report retrievals of COClF (carbonyl chlorofluoride) based on atmospheric chemistry experiment (ACE) solar occultation spectra recorded at tropical and mid-latitudes during 2004-2005. The COClF molecule is a temporary reservoir of both chlorine and fluorine and has not been measured previously by remote sensing. A maximum COClF mixing ratio of (10^-12 per unit volume, 1 sigma) is measured at 28 km for tropical and subtropical occultations (latitudes below 20^° in both hemispheres) with lower mixing ratios at both higher and lower altitudes. Northern hemisphere mid-latitude mixing ratios (30-50°N) resulted in an average profile with a peak mixing ratio of , 1 sigma, at 27 km, also decreasing above and below that altitude. We compare the measured average profiles with the one reported set of in situ lower stratospheric mid-latitude measurements from 1986 and 1987, a previous two-dimensional (2-D) model calculation for 1987 and 1993, and a 2-D-model prediction for 2004. The measured average tropical profile is in close agreement with the model prediction; the northern mid-latitude profile is also consistent, although the peak in the measured profile occurs at a higher altitude (2.5-4.5 km offset) than in the model prediction. Seasonal average 2-D-model predictions of the COClF stratospheric distribution for 2004 are also reported.     

A second-order ADI scheme for three-dimensional parabolic differential equations

A second-order unconditionally stable ADI scheme has been developed for solving three-dimensional parabolic equations. This scheme reduces three-dimensional problems to a succession of one-dimensional problems. Further, the scheme is suitable for simulating fast transient phenomena. Numerical examples show that the scheme gives an accurate solution for the parabolic equation and converges rapidly to the steady state solution. © 1998 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 14:159–168, 1998     

High-performance MC-CDMA via carrier interferometry codes

This paper introduces the principles of interferometry to multicarrier code division multiple access (MC-CDMA). Specifically, we propose the use of MC-CDMA with novel carrier interferometry (CI) complex spreading codes. The CI/MC-CDMA method, applied to mobile wireless communication systems, offers enhanced performance and flexibility relative to MC-CDMA with conventional spreading codes. Specifically, assuming a frequency selective Rayleigh-fading channel, CI/MC-CDMAs performance matches that of orthogonal MC-CDMA using Hadamard-Walsh codes up to the MC-CDMA N user limit; and, CI/MC-CDMA provides the added flexibility of going beyond N users, adding up to N-1 additional users with pseudo orthogonal positioning. When compared to MC-CDMA schemes capable of supporting greater than N users, CI/MC-CDMAs performance exceeds that of MC-CDMA. Additionally, this new system is analyzed in the presence of phase jitters and frequency offsets and is shown to be robust to both cases     

A New ADI Scheme for Solving Three-Dimensional Parabolic Equations with First-Order Derivatives and Variable Coefficients

An ADI scheme for solving three-dimensional parabolic equations withfirst-order derivatives and variable coefficients has been developed basedon our previous papers and the idea of the modified upwind differencescheme. This ADI scheme is second-order accurate and unconditionallystable. Further, a small parameter can be chosen which makes it suitablefor simulating fast-transient phenomena or for computations on fine spatialmeshes. The method is illustrated with numerical examples.     

Synthesis, Characterization and Biological Evaluation of Fe (III), Co (II), Ni(II), Cu(II), and Zn(II) Complexes with Tetradentate Schiff Base Ligand Derived from Protocatechualdehyde with 2-Aminophenol

Schiff base ligand (H₃L) was prepared from the condensation reaction of protochatechualdehyde (3,4-dihydroxybenzaldhyde)with 2-amino phenol. From the direct reaction of the ligand (H₃L) with Co(II), Ni(II) and Cu(II) chlorides, and Fe(III)and Zn(II)nitrates in 2?M/1?L molar ratio, the five new neutral complexes were prepared. The characterization of the newly formed compounds was done by ¹H NMR, UV?CVis, and IR spectroscopy and elemental analysis. The in vitro antibacterial activity of the metal complexes was studied and compared with that of free ligand.     

Reflectance near-infrared spectroscopic method with a chemometric technique using partial least squares multivariate calibration for simultaneous determination of chondroitin, glucosamine, and ascorbic acid

A reflectance near-infrared (RNIR) spectroscopy method was developed for simultaneous determination of chondroitin (CH), glucosamine (GO), and ascorbic acid (AS) in capsule powder. A simple preparation of the sample was done by grinding, sieving, and compression of the powder sample for improving RNIR spectra. Partial least squares (PLS-1 and PLS-2) was successfully applied to quantify the three components in the studied mixture using information included in RNIR spectra in the 4240-9780 cm(-1) range. The calibration model was developed with the three drug concentrations ranging from 50 to 150% of the labeled amount. The calibration models using pure standards were evaluated by internal validation, cross-validation, and external validation using synthetic and pharmaceutical preparations. The proposed method was applied for analysis of two pharmaceutical products. Both pharmaceutical products had the same active principle and similar excipients, but with different nominal concentration values. The results of the proposed method were compared with the results of a pharmacopoeial method for the same pharmaceutical products. No significant differences between the results were found. The standard error of prediction was 0.004 for CH, 0.003 for GO, and 0.005 for AS. The correlation coefficient was 0.9998 for CH, 0.9999 for GO, and 0.9997 for AS. The highly accurate and precise RNIR method can be used for QC of pharmaceutical products.     

Random scheduling based on transmission delay and buffer size for hop-based burst-cluster transmission in OBS networks

Hop-based burst-cluster transmission improves fairness significantly in OBS ring networks. However, in mesh networks, the overall burst loss probability increases using the method because the transmission of a burst-cluster from an ingress node is often synchronized with a burst-cluster from another ingress node. In order to resolve the synchronization issue, we propose in this article the utilization of random scheduling for hop-based burst-cluster transmission. In random scheduling, the maximum waiting time is determined in advance from the maximum acceptable delay of an IP packet and the buffer size of the ingress node. Every time a burst-cluster is generated, a scheduler derives the actual waiting time at random based on the obtained maximum waiting time. When a timer becomes the actual waiting time, the burst cluster is transmitted from the scheduler. By simulation, we evaluate the effectiveness of random scheduling for NSFNET. Numerical examples show that the random scheduling can resolve the synchronization issue and can decrease the overall burst loss probability. In addition, it is shown that random scheduling can also improve the fairness significantly.     

Design of low-frequency ultrasonic sensors for the analysis of the draining stage of cheese production

This work presents a new ultrasonic system with a transmission mode in the 100-200 kHz frequency range. The system, composed of ultrasonic point sources, is used to monitor the mechanical properties of cheese during the early phases of production. First, our specialized sensor system is presented, and then the results obtained with the system model are compared to the results of actual experiments using the system to monitor the evolution of the medium during draining. The results of a rheological compliance test and shock pulse ultrasonic amplitude measurements agree and correspond quite accurately to the mechanical properties of the evolving physical state of the medium. This method could be used in the future to study the effect on the final cheese quality of the process parameters that interfere with cheese grain consolidation during the draining process.     

40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis

The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.     

A study of generalized logistic distributions

Because of their flexibility, recently, much attention has been given to the study of generalized distributions. A complete study of the beta generalized logistic distribution (type IV) is proposed, introducing an approximate form for the median and deducing the mean deviation from the mean and the median. A complete parameter estimation using the method of maximum likelihood and the method of moments is presented. Some characteristic properties of the generalized logistic distribution type I are discussed. Also, a highlight to some properties of an analog distribution to the generalized logistic distribution type IV, discussed by Zografos and Balakrishnan [1], is presented.