Digital decoder for phase-delay coded data

Coded or modulated digital data converts to nonreturn to zero /NRZ/ data. Technique includes logic implementation and pertinent timing diagrams. Demodulation to NRZ facilitates digital logic operations on incoming data. Phase-delay modulation has advantage of inherent self-timing not present in NRZ modulation

Decontextualizing contextual inversion

Contextual inversion, introduced as an analytical tool by David Lewin, is a concept of wide reach and value in music theory and analysis, at the root of neo-Riemannian theory as well as serial theory, and useful for a range of analytical applications. A shortcoming of contextual inversion as it is currently understood, however, is, as implied by the name, that the transformation has to be defined anew for each application. This is potentially a virtue, requiring the analyst to invest the transformational system with meaning in order to construct it in the first place. However, there are certainly instances where new transformational systems are continually redefined for essentially the same purposes. This paper explores some of the most common theoretical bases for contextual inversion groups and considers possible definitions of inversion operators that can apply across set class types, effectively decontextualizing contextual inversions.Accepted manuscrip

The Electronic Ground State Energy Problem: a New Reduced Density Matrix Approach

We present here a formulation of the electronic ground-state energy in terms of the second order reduced density matrix, using a duality argument. It is shown that the computation of the ground-state energy reduces to the search of the projection of some two-electron reduced Hamiltonian on the dual cone of $N$-representability conditions. Some numerical results validate the approach, both for equilibrium geometries and for the dissociation curve of N$_2$

Variational methods in relativistic quantum mechanics

This review is devoted to the study of stationary solutions of linear and nonlinear equations from relativistic quantum mechanics, involving the Dirac operator. The solutions are found as critical points of an energy functional. Contrary to the Laplacian appearing in the equations of nonrelativistic quantum mechanics, the Dirac operator has a negative continuous spectrum which is not bounded from below. This has two main consequences. First, the energy functional is strongly indefinite. Second, the Euler-Lagrange equations are linear or nonlinear eigenvalue problems with eigenvalues lying in a spectral gap (between the negative and positive continuous spectra). Moreover, since we work in the space domain R^3, the Palais-Smale condition is not satisfied. For these reasons, the problems discussed in this review pose a challenge in the Calculus of Variations. The existence proofs involve sophisticated tools from nonlinear analysis and have required new variational methods which are now applied to other problems

Keeping the dream alive: Managing the Space Station Program, 1982 to 1986

The management is described and analyzed of the formative years of the NASA Space Station Program (1982 to 1986), beginning with the successful initiative for program approval by Administrator James M. Beggs through to the decision to bring program management to Reston, Virginia. Emphasis is on internal management issues related to the implementation of the various phases of the program. Themes examined are the problem of bringing programmatic and institutional interests together and focusing them to forward the program; centralized versus decentralized control of the program; how the history of NASA and of the individual installations affected the decisions made; and the pressure from those outside NASA. The four sections are: (1) the decision to build the space station, (2) the design of the management experiment, (3) the experiment comes to life, and (4) the decision reversal

Scalar Field Theory at Finite Temperature in D=2+1

We discuss the $\phi^6$ theory defined in $D=2+1$-dimensional space-time and assume that the system is in equilibrium with a thermal bath at temperature $\beta^{-1}$. We use the $1/N$ expansion and the method of the composite operator (CJT) for summing a large set of Feynman graphs.We demonstrate explicitly the Coleman-Mermin-Wagner theorem at finite temperature.Comment: 12 pages, 1 figure. To be published in Journal Mathematical Physics, typos adde

Decision making processes in people with symptoms of acute myocardial infarction: qualitative study

Objective To identify, the themes that influence decision making processes used by patients with symptoms of acute myocardial infarction. Design Qualitative study using semistructured interviews. Setting Two district hospitals in North Yorkshire. Participants 22 patients admitted to hospital with confirmed second, third, or fourth acute myocardial infarction. Main outcome measure Patients' perceptions of their experience between the onset of symptoms and the decision to seek medical help. Results Six main themes that influence the decision making process were identified: appraisal of In symptoms, perceived risk, previous experience, psychological and emotional factors, use of the NHS, and context of the event. Conclusions Knowledge of symptoms may not be enough to promote prompt action in the event of an acute myocardial infarction. Cognitive and emotional processes, individual beliefs and values, and the influence of the context of the event should also be considered in individual interventions designed to reduce delay in the event of symptoms of acute myocardial infarction

A simple screening method for determining knowledge of the appropriate levels of activity and risk behaviour in young people with congenital cardiac conditions

Objective: To assess a novel method for assessing risk and providing advice about activity to children and young people with congenital cardiac disease and their parents. Design and setting: Questionnaire survey in outpatient clinics at a tertiary centre dealing with congenital cardiac disease, and 6 peripheral clinics. Interventions: Children or their parents completed a brief questionnaire. If this indicated a desire for help, or a serious mismatch between advised and real level of activity, they were telephoned by a physiotherapist. Main measures of outcome: Knowledge about appropriate levels of activity, and identification of the number exercising at an unsafe level, the number seeking help, and the type of help required. Results: 253/258 (98.0%) questionnaires were returned, with 119/253 (47.0%) showing incorrect responses in their belief about their advised level of exercise; 17/253 (6.7%) had potentially dangerous overestimation of exercise. Asked if they wanted advice 93/253 (36.8%) said “yes”, 43/253 (17.0%) “maybe”, and 117/253 (46.2%) “no”. Of those contacted by phone to give advice, 72.7% (56/77) required a single contact and 14.3% (11/77) required an intervention that required more intensive contact lasting from 2 up to 12 weeks. Of the cohort, 3.9% (3/77) were taking part in activities that put them at significant risk. Conclusions: There is a significant lack of knowledge about appropriate levels of activity, and a desire for further advice, in children and young people with congenital cardiac disease. A few children may be at very significant risk. These needs can be identified, and clinical risk reduced, using a brief self-completed questionnaire combined with telephone follow-up from a suitably knowledgeable physiotherapist