Fire extinguishment in oxygen enriched atmospheres

Current state-of-the-art of fire suppression and extinguishment techniques in oxygen enriched atmosphere is reviewed. Four classes of extinguishment action are considered: cooling, separation of reactants, dilution or removal of fuel, and use of chemically reactive agents. Current practice seems to show preference for very fast acting water spray applications to all interior surfaces of earth-based chambers. In space, reliance has been placed on fire prevention methods through the removal of ignition sources and use of nonflammable materials. Recommendations are made for further work related to fire suppression and extinguishment in oxygen enriched atmospheres, and an extensive bibliography is appended

Synchronizing Sequencing Software to a Live Drummer

Copyright 2013 Massachusetts Institute of Technology. MIT allows authors to archive published versions of their articles after an embargo period. The article is available at

Rapid deconvolution of low-resolution time-of-flight data using Bayesian inference

The deconvolution of low-resolution time-of-flight data has numerous advantages, including the ability to extract additional information from the experimental data. We augment the well-known Lucy-Richardson deconvolution algorithm using various Bayesian prior distributions and show that a prior of second-differences of the signal outperforms the standard Lucy-Richardson algorithm, accelerating the rate of convergence by more than a factor of four, while preserving the peak amplitude ratios of a similar fraction of the total peaks. A novel stopping criterion and boosting mechanism are implemented to ensure that these methods converge to a similar final entropy and local minima are avoided. Improvement by a factor of two in mass resolution allows more accurate quantification of the spectra. The general method is demonstrated in this paper through the deconvolution of fragmentation peaks of the 2,5-dihydroxybenzoic acid matrix and the benzyltriphenylphosphonium thermometer ion, following femtosecond ultraviolet laser desorption

Modification of the simple mass balance equation for calculation of critical loads of acidity.

Over the last few years, the simple mass balance equation for the calculation of critical loads of acidity has been gradually modified as the underlying critical load concepts have developed and as problems with particular forms of the equation have been identified, through application in particular countries. The first major update of the equation took place following a workshop held in Vienna, Austria (Hojesky et al. 1993). The workshop was held to discuss problems which had been identified when the then current form of the equation was applied in countries with high rainfall. The problems had largely arisen because of simplifications and assumptions incorporated into the early formulation of the equation. The equation was reformulated to overcome the problems identified at the workshop. However, further problems were identified when the reformulated equation was applied in the UK in situations with a combination of high rainfall, large marine inputs and widespread occurrence of organic soils. A small workshop was, therefore held in Grange-over-Sands, UK in late 1993 to dicuss the problems and to further re-evaluate the equation. The problems had arisen in the UK because of simplifications and assumptions made in the formulation concerning, in particular, cation leaching and uptake. As a result, a more rigorous treatment of these variables was incorporated into the equation. The reformulation of the equation, as derived at the September 1993 workshop is described below

Research summary

The final report for progress during the period from 15 Nov. 1988 to 14 Nov. 1991 is presented. Research on methods for analysis of sound propagation through the atmosphere and on results obtained from application of our methods are summarized. Ten written documents of NASA research are listed, and these include publications, manuscripts accepted, submitted, or in preparation for publication, and reports. Twelve presentations of results, either at scientific conferences or at research or technical organizations, since the start of the grant period are indicated. Names of organizations to which software produced under the grant was distributed are provided, and the current arrangement whereby the software is being distributed to the scientific community is also described. Finally, the names of seven graduate students who worked on NASA research and received Rensselaer degrees during the grant period, along with their current employers are given

Low-frequency sound propagation modeling over a locally-reacting boundary using the parabolic approximation

There is substantial interest in the analytical and numerical modeling of low-frequency, long-range atmospheric acoustic propagation. Ray-based models, because of frequency limitations, do not always give an adequate prediction of quantities such as sound pressure or intensity levels. However, the parabolic approximation method, widely used in ocean acoustics, and often more accurate than ray models for lower frequencies of interest, can be applied to acoustic propagation in the atmosphere. Modifications of an existing implicit finite-difference implementation for computing solutions to the parabolic approximation are discussed. A locally-reacting boundary is used together with a one-parameter impedance model. Intensity calculations are performed for a number of flow resistivity values in both quiescent and windy atmospheres. Variations in the value of this parameter are shown to have substantial effects on the spatial variation of the acoustic signal

Min-Max Theorems for Packing and Covering Odd (u,v)(u,v)-trails

We investigate the problem of packing and covering odd $(u,v)$-trails in a graph. A $(u,v)$-trail is a $(u,v)$-walk that is allowed to have repeated vertices but no repeated edges. We call a trail odd if the number of edges in the trail is odd. Let $\nu(u,v)$ denote the maximum number of edge-disjoint odd $(u,v)$-trails, and $\tau(u,v)$ denote the minimum size of an edge-set that intersects every odd $(u,v)$-trail. We prove that $\tau(u,v)\leq 2\nu(u,v)+1$. Our result is tight---there are examples showing that $\tau(u,v)=2\nu(u,v)+1$---and substantially improves upon the bound of $8$ obtained in [Churchley et al 2016] for $\tau(u,v)/\nu(u,v)$. Our proof also yields a polynomial-time algorithm for finding a cover and a collection of trails satisfying the above bounds. Our proof is simple and has two main ingredients. We show that (loosely speaking) the problem can be reduced to the problem of packing and covering odd $(uv,uv)$-trails losing a factor of 2 (either in the number of trails found, or the size of the cover). Complementing this, we show that the odd-$(uv,uv)$-trail packing and covering problems can be tackled by exploiting a powerful min-max result of [Chudnovsky et al 2006] for packing vertex-disjoint nonzero $A$-paths in group-labeled graphs

The pathogenesis of the anaerobic corynebacterium diphtheriae, anaerobic diphtheroid, and anaerobic leptothrix infections in relation to the psychoses, neuroses, and neurotoxic states, compared with 260 cases of symptomatic physical disorder (illustrated by 17 tables)

The subject of this thesis is the outcome of what might be termed a 'hereditary interest' in the complex problem of the relationship of chronic infections to the psychoses and allied mental disorders. Circumstances enabled me, while still a student, to undertake very humbly the continuation of my father's researches in the Scottish Asylums' Laboratory at a point where his illness and death mic:ht have proved the closing of a long and arduous chapter. That this would have been so is, as far as I know, borne out by the fact that up to the present no work directly bearing on his later bacteriological studies has been published. The researches I have undertaken during the past six rears have been an attempt to elucidate more clearly what exactly are the bacteriological factors at work, and, further, in what manner they attach the economy generally, and with what result. In my endeavour to verify and extend Ford Robertson's views I have been singularly fortunate.After nearly two years in the Laboratory of the Scottish Asylums' I had the opportunity as honorary Bacteriologist and Pathologist to the Southport Infirmary and assistant to Dr E. Cronin Lowe, (consulting pathologist and director of the Southport Infirmary laboratory) of studying a large number of private and hospital patients during the course of two years work. In addition to undertaking bacteriological research by anaerobic methods, it fell to me to organise a pathological clinique, the object of which was to aid the physician in the diagnosis and treatment of obscure physical disorders by the method of a "diagnostic survey". The scheme evolved necessitated a sz stematic study of each patient by haematological an biochemical tests including functional efficiency tests such as the glucose tolerance and fractional test meal. Each case was also studied with a view to discovering if possible some underlying bacteriological infective condition which might have a bearing upon the state of the patient. In the course of undertaking a large number of patients by this method of approach some fifteen mental and borderland cases came under review. In many instances I was much struck by their similarity to control patients in the underlying physical disturbance found, and, while in this respect there was something in common, it was striking to note in some of the borderland, and certainly in those who were definitely, mental, the absence of clinical symptomatology, in spite of the fact that they showed more gross functional physical disorder on the average than did the non-mental cases. In gastric disorders for example non-mental patients, almost without exception, gave a clear clinical history referrible to that organ. In two mental patient however no such evidence past or present was ascertainable, although both were found to be suffering from severe gastritis and disordered secretory function. Exceptional as these two cases may appear to b this experience, which has been by no means confined to the gastric mechanism, has been enormously amplified by the work I have carried out since then. In the study of the bacteriological flora, especially of the intestine, there were bacterial elements common to the majority of the fifteen cases which, on the other hand, were relatively infrequently met with in ordinary hospital patients. This fact further impressed itself upon me when it had to be realised that these additional infective factors were in every respect similar to those so commonly seen in the course of routine bacteriological work at the Scottish Asylums Laboratory. This evidence I believed at the time formed a valuable link which, if opportunity offered, might result in a chain of facts establishing the importance of this group of bacteria.Early in November, 1927, the New Reception hospital, (Wantage House), of St Andrews, Northampton, was opened, and I was offered the opportunity of organising the very work which had been begun amongst cases of mental disorder at the Southport Infirmary. It is not often one is fortunate enough to start from the foundation a scheme of research with a limited number of patients whose whole care clinically and scientifically comes within one's own province. Further, the facilities afforded in each department are those of the best equipped modern general hospital in miniature, a fact which has very materially contributed, not only to the extension of research, but to the correlation as far as my knowledge has permitted, of the wide range of facts and observations that have been collected in the course of nearly three years.By experience of the value both scientific and therapeutic of the diagnostic survey method of research led me to adopt it in an extended. form on all cases admitted to ':Vantage House. The following is a brief outline of t' :e scheme of research which up to the present has been undertaken on 155 patients, 137 of whom presented definite mental disorders.(1) Systematic physical examination including blood pressure, central nervous system, teeth, etc. (2) Examination of upper respirator- passages for evidence of focal infection. (3) Laboratory tests. a. Cytology of the blood. b. Biochemical examination of the blood. Non-protein nitrogen, CO₂, calcium, Van-den-Bergh, and phosphates. c. Gastric analysis by fractional method. d. Glucose tolerance. e. Urine, 24 hrs. sample. Biochemical qualitative and quantitative: examinations and cytological. f. Intestinal content. Chemical and microscopical. g. Cerebro-spinal fluid. Cytological, biochemical qualitative and quantitative in about 1/4 of the cases. (4) Bacteriological examinations of the foci throughout the alimentary canal in all cases by the anaerobic methods given in this thesis. Pelvic organs and accessory sinuses in some. (5) Radiography. Teeth and accessory sinuses in all cases, and gastro-intestinal tract in some. (6) The study of the psychological aspects past and present of each case, especially in relation to heredity, environment, and past physical disorder The above tests have been repeated as circumstances demanded and, with the exception of the gastric analysis and glucose tolerance, are carried out again case it has been possible,under ideal circumstances of observation and control, to study and where possible correlate the mental symptoms with the underlying physical disorders. The main outlines of this scheme and the circumstances that led up to its inception have been mentioned so that those whose position it is to criticise and judge should know that the basis of this thesis has been a wide one and that the views expressed therein have been given without conscious bias and in the hope that others may be stimulated to carry out similar researches

Tweed in Martensites: A Potential New Spin Glass

We've been studying the ``tweed'' precursors above the martensitic transition in shape--memory alloys. These characteristic cross--hatched modulations occur for hundreds of degrees above the first--order shape--changing transition. Our two--dimensional model for this transition, in the limit of infinite elastic anisotropy, can be mapped onto a spin--glass Hamiltonian in a random field. We suggest that the tweed precursors are a direct analogy of the spin--glass phase. The tweed is intermediate between the high--temperature cubic phase and the low--temperature martensitic phase in the same way as the spin--glass phase can be intermediate between ferromagnet and antiferromagnet.Comment: 18 pages and four figures (included