A preliminary examination of rater-determined versus Hayre's voice-based psychological parameters

Rater-determined data on depression, anxiety and mania on some twenty subjects, receiving varying medication in each case, were compared with Hayre's voice-based psychological stress parameter, $\text{H}{}_{\mathrm{<mtext>1</mtext>}}$, determined solely from the voices of the subjects. Each subject was asked by raters to read a given paragraph, from which one word was taken for analysis. The analysis employed spectrum analysis and further processing in order to obtain the raw data for calculating Hayre's voice-based psychological stress parameter, $\text{H}{}_{\mathrm{<mtext>1</mtext>}}$. A comparison of the two results shows that manic measures were not significantly discernible by raters whereas a ratio of depression (D) and anxiety measure (A) seems to be very definitely correlated with Hayre's voice-based parameter, $\text{H}{}_{\mathrm{<mtext>1</mtext>}}$. Further work is continuing since it seems to show considerable promise in quantifying psychological measures obtained solely from the voice of the subject.     

A note on optimal maintenance policies for deciding whether to repair or replace

A system deteriorates stochastically over time. When the deterioration reaches a critical level, the system has to be either repaired or replaced by a new one. Repairs are generally both less effective and less costly than a replacement. By modelling the problem as a semi-Markov decision process, an explicit expression is found for the optimal maintenance policy for minimizing the long run average cost per unit time. Some numerical results are given for a multi-state system.     

Electrocatalytic oxidation of methanol on Pt catalyst supported on nitrogen-doped graphene induced by hydrazine reduction

Hydrazine is often used to reduce graphene oxide (GO) to produce graphene. Recent observations suggested that when hydrazine is used to reduce GO, the resulting reduced graphene actually contains certain amounts of nitrogen dopants, which may influence the properties of the obtained material, and in some cases may be deployed for beneficial advantage. In this work, we prepared graphene oxide by the chemical oxidation method, then used either hydrazine or sodium borohydride (as a control) to reduce the graphene oxide to graphene and to explore the nature of the nitrogen functionalities introduced by hydrazine reduction. Pt nanoparticles were then deposited on the nitrogen doped (hydrazine-reduced) and undoped (control) graphene substrates, and the morphology, structure, and electrocatalytic methanol oxidation activity were characterized and evaluated. The results show that the nitrogen functional groups introduced into the graphene by hydrazine reduction greatly improve the electrocatalytic activity of the underlying Pt nanoparticles towards the methanol oxidation reaction.     

Facile single-step preparation of Pt/N-graphene catalysts with improved methanol electrooxidation activity

In this work, we describe a facile single-step approach for the simultaneous reduction of graphene oxide to graphene, functional doping of graphene with nitrogen, and loading of the doped graphene with well-dispersed platinum (Pt) nanoparticles using a solvent mixture of ethylene glycol and N-methyl-2-pyrrolidone. The as-prepared Pt/nitrogen-doped graphene (N-graphene) catalysts are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy while the electrocatalytic methanol oxidation properties of the catalysts are evaluated by cyclic voltammetry and chronoamperometry. Compared with an updoped Pt/graphene control catalyst, the Pt/N-graphene catalyst shows a narrower particle size distribution and improved catalytic performance. Considering the facile, green and effective single-step synthetic process for the Pt/N-graphene catalyst, the results are promising for the potential application of these materials in emerging fuel cell technologies.     

Steady vortical flow around a finite plate

An explicit solution for a layer of fluid with constant vorticitysurrounding a thin plate of finite length is obtained usingelementary conformal mapping methods. In the limit of largeplate length the behaviour of the solution near the ends ofthe plate tends to that of the previously known solution fora semi-infinite plate. Contour dynamics is used to investigatethe stability of the steady solutions.     

Cross-correlation of voice and heart rate as stress measures

Heart rate and O₂ uptake, etc. have been widely used to assess the physical fitness of human subjects. Recently developed Hayre voice-based parameters for physical stress or fatigue are validated by the results of this work. These parameters are not only non-obtrusive means of real time observation of clinical, educational and physical training of subjects but also provide a unique comparative means of monitoring physical fatigue among various professionals such as athletes, truck drivers, pilots and doctors of medicine, etc. Subjects of various ages running on a treadmill were instrumented for recording heart rate, EKG, treadmill speed and slope. The treadmill was run at 3·3 mph (90 m/min) and the grade was increased by one per cent a minute up to a maximum of 25 per cent and then the speed was increased by 0·2 mph until exhaustion. Each subject was asked to count from one to ten and utter two other preselected words separated by silence gaps in between for ease of analysis. An analysis of these utterances indicates that a monotonic increase in heart rate is highly correlated with Hayre parameters $\text{G}{}_{\mathrm{<mtext>1</mtext>}}$ and $\text{F}{}_{\mathrm{<mtext>1</mtext>}}$ mentioned above, up to the time of maximum stress and the associated peak heart rate of 175. After stopping the treadmill run and letting the subject sit down, the heart rate starts dropping rapidly whereas the Hayre stress parameter $\text{G}{}_{\mathrm{<mtext>1</mtext>}}$ tends to increase to a saturation level, thus verifying that the continued physically stressed state of the subject has not significantly lessened as one would perceive from the above mentioned drop in heart rate.     

Evaluating force field accuracy with long-time simulations of a β-hairpin tryptophan zipper peptide

We have combined graphics processing unit-accelerated all-atom molecular dynamics with parallel tempering to explore the folding properties of small peptides in implicit solvent on the time scale of microseconds. We applied this methodology to the synthetic β-hairpin, trpzip2, and one of its sequence variants, W2W9. Each simulation consisted of over 8 μs of aggregated virtual time. Several measures of folding behavior showed good convergence, allowing comparison with experimental equilibrium properties. Our simulations suggest that the intramolecular interactions of tryptophan side chains are responsible for much of the stability of the native fold. We conclude that the ff99 force field combined with ff96 φ and ψ dihedral energies and an implicit solvent can reproduce plausible folding behavior in both trpzip2 and W2W9.     

Optimization of a direct spectrophotometric method to investigate the kinetics and inhibition of sialidases

Backgrounds

Streptococcus pneumoniae expresses three distinct sialidases, NanA, NanB, and NanC, that are believed to be key virulence factors and thus, potential important drug targets. We previously reported that the three enzymes release different products from sialosides, but could share a common catalytic mechanism before the final step of product formation. However, the kinetic investigations of the three sialidases have not been systematically done thus far, due to the lack of an easy and steady measurement of sialidase reaction rate.

Results

In this work, we present further kinetic characterization of pneumococcal sialidases by using a direct spectrophotometric method with the chromogenic substrate p-nitrophenyl-N-acetylneuraminic acid (p-NP-Neu5Ac). Using our assay, the measured kinetic parameters of the three purified pneumococcal sialidase, NanA, NanB and NanC, were obtained and were in perfect agreement with the previously published data. The major advantage of this alternative method resides in the direct measurement of the released product, allowing to readily determine of initial reaction rates and record complete hydrolysis time courses.

Conclusion

We developed an accurate, fast and sensitive spectrophotometric method to investigate the kinetics of sialidase-catalyzed reactions. This fast, sensitive, inexpensive and accurate method could benefit the study of the kinetics and inhibition of sialidases in general.     

Personality parameter detection from speech

A simple binary decision tree technique is applied to a speech spectrum of single words in conjunction with a special technique to compress $\text{20 000 × 20 000}$ data plane to $\text{500 × 500}$ in the first step, and then to 10 identifiable classifiers in the second step. The results of this bit compression/usable information preservation scheme reduce the task of pattern recognition of personality parameters to a manageable one both in a data size and in a processing time sense. Moreover it yields results which are highly correlated with Seagal parameters derived from clinical interviews.     

A Simple Dynamic Method for Obtaining Inspection Schedules

A method for obtaining inspection schedules is proposed for situations where it is difficult to quantify the costs associated with inspections and undetected failure, or when these costs vary in time. After each inspection, the next inspection is scheduled so that there is only a small, specified probability that a failure goes undetected for longer than a specified time. Some properties of the inspection times are derived, and numerical illustrations are given for some particular cases.