Saturation of the net electron excitation of the CO2(00°1) laser level as a function of discharge input energy

Measurements are made of the small signal gain in He:CO₂ and He:N₂:CO₂ gas mixtures as a function of pulsed discharge energy. In all case it is found that the gain saturates as the discharge energy is increased. Thermal effects cannot account for this gain saturation which appears to be a fundamental property of high-pressure CO₂ discharges.     

Moiré fringes in metrology

Moiré fringe phenomena have been exploited in a wide range of transducers, particularly in the field of engineering metrology. Paying particular attention to developments which have taken place during the last 15 years, the paper presents a cross-section of moiré techniques for the measurement of displacement, surface topography, deformation, vibration and refractive index gradient.     

Towards the development of an immuno MALDI (iMALDI) mass spectrometry assay for the diagnosis of hypertension

The renin-angiotensin-aldosterone system (RAAS) plays an essential role in the regulation of plasma volume and arterial blood pressure. One of the most common diseases of the RAAS is the autonomous production of aldosterone by the adrenal glands, caused by either bilateral adrenal hyperplasia or an aldosterone-producing adenoma. This condition, known as primary aldosteronism, is a treatable and often curable form of hypertension. The measurement of plasma renin activity (PRA), as determined by radioimmunoassay for angiotensin I is essential to the diagnosis of primary aldosteronism. However, accurate determination of PRA is often hampered by low plasma concentrations of angiotensin I. Here, we report the use of immuno-MALDI (iMALDI) as a highly sensitive and specific method for the absolute quantitation of angiotensin I in plasma. iMALDI permits concentration determination by affinity-capture of angiotensin I and a stable-isotopically labeled standard (SIS) peptide on immobilized anti-peptide antibodies. The affinity beads are placed on the MALDI target, permitting automated analysis of large numbers of patient samples. Pretreatment of the plasma is not required, and this method is suitable for the accurate determination of angiotensin I in whole plasma. The calibration curve generated using this method was linear over a 50-fold concentration range in plasma, with a correlation coefficient of 0.984. MS/MS sequence confirmation provides absolute specificity. The iMALDI angiotensin I assay, therefore, has the potential to be developed into a method for determining PRA that has advantages in time, in specificity, and in safety.     

Decrease in frequency of maximum far-infra-red power absorption of polar fluids with temperature

Summary It is shown how the inherent nonlinearity of the equations of motion of coupled dipoles qualitatively explains a number of features of the observed far-infra-red spectrum of polar fluids. These include the almost linear increasing temperature and the temperature independence of the band width.

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Riassunto Si mostra come l'inerente non linearità delle equazioni di moto di dipoli accoppiati spiega qualitativamente un numero di comportamenti dello spettro osservato nel lontano infrarosso di fluidi polari. Questi includono il decremento quasi lineare della posizione del picco del coefficiente di assorbimento di potenza FIR con l'aumento della temperatura e l'indipendenza della temperatura dell'ampiezza di banda.

     

A simple optimal control problem involving approximation by monotone functions

For the problem of minimizing a suitable type of integral functionalJ[y] in the class _k of real, monotone nonincreasing functionsy which are Lipschitzian on a compact interval [a, b] with Lipschitz constantk, there is presented an existence theorem and a characterization of minimizing functions as solutions, in the sense of Filippov, of associated differential equations whose members involve discontinuities. For the problem of minimizingJ[y] in the class of all real, monotone nonincreasing functions for whichJ[y] exists, there is established an existence theorem and proof that, under suitable hypotheses, a solution of this second problem is the limit of solutions of the aforementioned problem ask . For the particular case in whichJ[y] is the integral of 1/2[y –h(t)]², whereh(t) is measurable and bounded on [a, b], it is shown that the minimizing function forJ[y] in the class is the derivative almost everywhere of the least concave majorant of the functionH(t)= ₀ ^t h(s)ds, t [a,b].This research was supported by the Office of Scientific Research, Office of Aerospace Research, United States Air Force, Grant No. AF-AFOSR-749-65.     

High-average-power, 1-MW peak-power self-mode-locked Ti:sapphire oscillator

We describe a novel self-mode-locked Ti:sapphire ring laser that produces 13-fs pulses with peak powers exceeding 1 MW, pulse energies of 13 nJ, and average mode-locked output powers of 1.5 W at a cavity repetition frequency of 110 MHz. A complete resonator analysis describing the optimum mode-locking configuration is presented, together with fringe-resolved autocorrelation and sonogram measurements of the output pulses.