On the existence and multiplicity of topologically twisting incompressible HH-harmonic maps and a structural H-condition

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System controls challenges of hypersonic combined-cycle engine powered vehicles

Hypersonic aircraft with air-breathing engines have been described as the most complex and challenging air/space vehicle designs ever attempted. This is particularly true for aircraft designed to accelerate to orbital velocities. The propulsion system for the National Aerospace Plane will be an active factor in maintaining the aircraft on course. Typically addressed are the difficulties with the aerodynamic vehicle design and development, materials limitations and propulsion performance. The propulsion control system requires equal materials limitations and propulsion performance. The propulsion control system requires equal concern. Far more important than merely a subset of propulsion performance, the propulsion control system resides at the crossroads of trajectory optimization, engine static performance, and vehicle-engine configuration optimization. To date, solutions at these crossroads are multidisciplinary and generally lag behind the broader performance issues. Just how daunting these demands will be is suggested. A somewhat simplified treatment of the behavioral characteristics of hypersonic aircraft and the issues associated with their air-breathing propulsion control system design are presented

Congenital heart disease in the paediatric age-group

A large number of congenital anomalies of the heart are presented and discussed. All of the cases were within the paediatric age- group, the majority being less than five years of age. The symptoms and signs are discussed in detail, and the results of electro- cardiography and X -ray investigation presented. The results of cardiac catheterization are given in certain cases. The diagnosis was tested by each or all of these methods, and, too often by autopsy. Further proof has accrued since the completion of the thesis and no undue reversal of opinion has ensued.In the intervening time also, further information concerning the general attitude towards these cases has been obtained. It is essential that each case should be fully investigated at the first appearance of the child in thè out -patient department; too often the child is left "until it is bigger ", or "until it is in trouble ", before every avenue is explored. The author unfortunately shared this attitude, until the frequency of death during the "follow up" period showed how lethal this neglect could be. Potentially curable cases such as atypical patent ductus arteriosus were found at autopsy, because retrograde angiography or cardiac catheterization was not carried out in time.Similarly operation should not be denied the youngest of children who have such lesions as tetralogy of Fallot or pulmonary stenosis with a normal aortic root. Such cases too often die while waiting for the "great vessels to increase in size ". The indication for operation are the classic ones of paroxysmal dyspnoea, and limitation of effort; to these must be added failure of growth, epitomized by a sinister downward progress of percentiles. These and more subtle signs of '!failure to thrive ", are best appreciated by those with a paediatric rather than a cardiological training.Even if mistakes are made, thoracotomy in experienced hands will be safe enough to allow of direct examination of the lesion, if pre- operative assessment is incomplete. Undoubtedly the attendance of personnel with physiological apparatus for the measurement of pressure and oxygen tension will increase the efficiency of the surgeon and may lead to the discovery of better methods of treatment.So then it is suggested that every child who shows symptoms be considered as potentially operable. Thus all cyanotic cases should have angiocardiography if the diagnosis is not immediately obvious. Equally, cardiac catheterization should be carried out in allacyanotic cases with symptoms unless a "Gibsori' murmur, absent femoral pulses, or other undoubted criteria make the diagnosis reasonably absolute. The latter technique is, as the author has found, perfectly applicable to all cases, except perhaps premature infants - in one case an infant of 4 Kgms. was subjected to this investigation - with the happiest results.The high morbidity and mortality in these children is a challenge to the therapeutic acumen of the paediatrician, and demand his constant review and supervision of the individual case. Fluoroscopy and interpretation of the electrocardiogram should be within the province of the paediatric physician, and, if the apparatus is available he should be able to turn his hand to cardiac catheterization

Studies in the Field of Natural Products

The inter-relationship of the three mould metabolites atrovenetin, herqueinone, and norherqueinone has been elucidated by the discovery that deoxynorherqueinone (obtained by reduction of norherqueinone with zinc and acetic acid) is identical with atrovenetin. A study of the spectral properties of the three mould metabolites and their degradation products has been undertaken, from which it appeared that atrovenetin, deoxyherqueinone, xanthoherguein, and norxanthoherquein (the last two being obtained by acid hydrolysis of herqueinone and norhergueinone respectively) are all derivatives of 9-hydroxyperinaphthenone. This has been confirmed by suitable degradations, among which may be mentioned the nitric acid oxidation of xanthoherquein, norxanthoherquein, and atrovenetin to nitrococussic acid; and the oxidation of atrovenetin with alkaline hydrogen peroxide to a derivative of 2:7-dihydroxynaphthalic anhydride. The available data have all been correlated in terms of unique structures for atrovenetin, and many of its derivatives and degradation products, and for xanthoherguein. In particular, the compound, C15H14N2O9.H2O, obtained by previous workers by oxidising atrovenetin with concentrated nitric acid, has been reinvestigated, and assigned a phthalide type of structure consistent with all its chemical and physical properties (including its nuclear magnetic resonance spectrum). During the course of the work on atrovenetin, 2:7-dihydroxynaphthalic anhydride has been synthesised, and the spectra of this and seven other naphthalic anhydrides have been measured. A relationship between the amount of hydrogen-bonding in these compounds, and the positions of their infrared absorption bands in the carbonyl region has emerged. The molecular skeletons of norherqueinone and herqueinone follow from the work on atrovenetin. The possible positions of the methoxyl group in herqueinone have been reduced to two, as a result of suitable degradations. Possible structures for herqueinone and its derivatives and degradation products have been discussed. The structure of the interesting plant product, anisoxide, has been confirmed by the synthesis of anisoxide itself, and of several of its degradation products. The biogenesis of C5 isoprenoid side-chains attached to aromatic nuclei has been discussed, with special reference to atrovenetin and anisoxide

On Krein-like theorems for noncanonical Hamiltonian systems with continuous spectra: application to Vlasov-Poisson

The notions of spectral stability and the spectrum for the Vlasov-Poisson system linearized about homogeneous equilibria, f_0(v), are reviewed. Structural stability is reviewed and applied to perturbations of the linearized Vlasov operator through perturbations of f_0. We prove that for each f_0 there is an arbitrarily small delta f_0' in W^{1,1}(R) such that f_0+delta f_0$is unstable. When$f_0$ is perturbed by an area preserving rearrangement, f_0 will always be stable if the continuous spectrum is only of positive signature, where the signature of the continuous spectrum is defined as in previous work. If there is a signature change, then there is a rearrangement of f_0 that is unstable and arbitrarily close to f_0 with f_0' in W^{1,1}. This result is analogous to Krein's theorem for the continuous spectrum. We prove that if a discrete mode embedded in the continuous spectrum is surrounded by the opposite signature there is an infinitesimal perturbation in C^n norm that makes f_0 unstable. If f_0 is stable we prove that the signature of every discrete mode is the opposite of the continuum surrounding it.Comment: Submitted to the journal Transport Theory and Statistical Physics. 36 pages, 12 figure

The iron Kalpha Compton Shoulder in transmitted and reflected spectra

We calculate the Equivalent Widht of the Core and the centroid energy and relative flux of the 1st order Compton Shoulder of the iron Kalpha emission line from neutral matter. The calculations are performed with Monte Carlo simulations. We explore a large range of column densities for both transmitted and reflected spectra, and study the dependence on the iron abundance. The Compton Shoulder is now becoming observable in many objects thanks to the improved sensitivity and/or energy resolution of XMM-Newton and Chandra satellites, and the present work aims to provide a tool to derive informations on the geometry and element abundances of the line emitting matter from Compton Shoulder measurements.Comment: 4 pages; accepted for publication in MNRA

Old thoughts in new dress : or, Today\u27s theology for laymen

https://place.asburyseminary.edu/ecommonsatsdigitalresources/1541/thumbnail.jp