PubMed Health⌕ Search

Biomedical subjects

N Levinson

Publications and source records attributed to N Levinson.

15 recordsLinked to original sources
PubMed1993

Psychodynamic factors contributing to esthetic dental failures.

Traditionally, dentistry has focused on biomedical and mechanotechnical approaches to patients' dental health care. Objective and quantifiable measurements, such as tooth form, occlusal function, color, and biological compatibility, are conventional indicators of success or failure. However, unlike most facets of dental practice, the attainment of an enhanced facial and dental appearance is influenced and measured by more abstract, psychological factors such as perception, ideal body image, self-image, and personal motivation. These complex concepts are affected by emotional and personality factors that develop during the life cycle. This article will explore a psychodynamic perspective of patients who are dissatisfied with the esthetics of their dental treatment, although the result may be functionally and esthetically acceptable.

Adolescent↗
PubMed1991

[Falls in elderly patients in an institution].

Falls among the elderly are a major concern of those caring for them. We studied the incidence of falls in institutionalized elderly, as well as the characteristics of those who fell and the causes of the falls, to determine how to prevent falling. A 2-month survey was conducted in Mishan, an institution in Raanana, and included 144 falls in 108 patients (447 women and 162 men, mean age 84) out of a total of 609 elderly. The prevalence of falls was 1426 per 1000 per year. Most cases of falls were first seen in the emergency room or wards for demented patients. The prevalence of falls among those receiving physiotherapy was only 1/3 that of those who did not. Old institutionalized patients tend to fall mainly while getting in and out of bed. Falls may result from medication such as sleeping pills and psychotropic drugs, but not diuretics. Falls are not inevitable, and measures can be applied to prevent them and thus reduce their frequency.

Accidental Falls↗
PubMed1988

Effect of heart rate alterations produced by atrial pacing on the pattern of diastolic filling in normal subjects.

To determine the effect of heart rate alterations on diastolic timing intervals and filling parameters, 10 normal patients were paced from the right atrium at 30 and 50 beats/min above their baseline rates. M-mode echocardiograms of the aortic valve, mitral valve and left ventricle were obtained and digitized at baseline and with each pacing rate. With increased atrial pacing, left ventricular systolic time became an increasingly greater proportion of cycle length while the diastolic filling period occupied a lesser proportion of the cycle length. The time to peak filling rate and the rapid filling period occupied a greater proportion of the diastolic filling period. The peak filling rate increased progressively with increased atrial pacing (baseline 128 +/- 19 mm/s, first paced rate 146 +/- 27 mm/s, p less than 0.05 vs baseline; second paced rate 167 +/- 23 mm/s, p less than 0.01 vs baseline and first paced rate). The early diastolic filling fraction and rapid filling fraction also increased with pacing. Increasing the heart rate resulted in an alteration of the time course of diastolic filling and extent of diastolic filling during the rapid filling period. Interventions that improve diastolic filling and increase heart rate may in part be due to heart rate changes.

Adult↗
PubMed1975

Deduction of Semi-Optimal Mollifier for Obtaining Lower Bound for N(0)(T) for Riemann's Zeta-Function.

A mollifier played a key role in showing N(0)(T) > 1/3N(T) for large T in ref. 1 [Levinson, N. (1974) Advan. Math. 13, 383-436]. A basic problem in ref. 1 was that of obtaining an upper bound for a sum of two terms, one larger than the other. Here a deductive procedure is given for finding a mollifier that actually minimizes the larger term. An Euler-Lagrange equation is obtained. (Optimization of the sum of both the major and minor terms appears to be formidable.) The actual improvement effected by the optimized mollifier over the ad hoc mollifier of ref. 1 is unfortunately only 1.4%. To obtain a usable mollifier it is necessary to blur the optimization procedure by smoothing at several stages of the deduction. The procedure is of more interest than the particular application because of the small improvement in this case.

Journal Article↗
PubMed1975

Almost All Roots of zeta(s) = a Are Arbitrarily Close to sigma = 1/2.

Let s = sigma + it. For any complex a, all but O(1/log log T) of the roots of zeta(s) = a in T < t < 2T lie in|sigma - 1/2| < (log log T)(2)/log T. The results extend easily to other functions satisfying a functional equation such as the Dirichlet L-functions, the Lerch functions, etc.

Journal Article↗
PubMed1974

Generalization of Recent Method Giving Lower Bound for N(o)(T) of Riemann's Zeta-Function.

Let h(s) = pi(-s/2)tau(s/2). Then, h(s)zeta(s) approximately h(s)H(s) + h(1 - s)H(1 - s) where H(s) = Sigma(1 - (log n)/log t/2pi)n(-s), n </= t/2pi, led to N(o)(T) >/= N(T)/3. Here the extension to H(s) approximately Sigma P (1 - (log n)/log t/2pi) n(-s) is made where P(x) is a polynomial such that P(0) = 0 and P(x) + P(1 - x) = 1. The earlier case is P(x) = x. The relevant formulas in the general case can be obtained explicitly by the earlier method used for P(x) = x, and, indeed, in some respects there is greater simplicity for the general case.

Journal Article↗
PubMed1973

Asymptotic Formula for the Coordinates of the Zeros of Sections of the Zeta Function, zeta(N)(s), Near s = 1.

The sum, Sigma1(N)n(-8) = zetaN(s), s = sigma + it, is called a section of the Riemann zeta function, zeta(s). Here an asymptotic formula, for large N, giving the location of the zeros of zetaN(s) near s = 1 will be demonstrated. In particular these zeros will lie in sigma < 1. Relationships between the location of the zeros of zetaN(s) and the zeros of zeta(s) were discovered by Turán. The location in sigma < 1 will also be demonstrated directly, without the asymptotic formula, together with results valid also when s - 1 is not small.

Journal Article↗
PubMed1972

omega-Theorems for Quotients of Zeta-Functions at Combinations of Points.

Theorem A. Let q >/= O and r >/= O be integers. Let s = sigma + it, let zeta(s) be the Riemann zeta-function, let G(o)(s) = 1, and [Formula: see text] and let F(s) = G(q)(s)/H(r)(s). Then as t --> infinity lim sup [unk]F(1 + it)[unk]/(log log t)(q+r+1) >/= (6/pi)(2))(r+1) exp {(q + r + 1)gamma}, where gamma is Euler's constant.Stronger results such as proved in [1] are valid, and in particular q and r can be allowed to increase with t as in [1]. Results involving the real part of the sum of the factors of G(q) and of the reciprocals of the factors of H(r) can be proved much as in [3].

Journal Article↗