Effect of Lethally Damaged Tumour Cells upon the Growth of Admixed Viable Cells in Diffusion Chambers

IT has been shown that the proliferation of a small viable tumour graft is stimulated by the presence of irreversibly X-ray damaged tumour cells (Revesz, 1958) or viable but genetically incompatible cells (Klein and Klein, 1956). Histological examination (Ringertz, Klein and Revesz, 1959) showed an enhanced granulation tissue formation in and around the implant. The intensity of this reaction was parallel to the stimulating effect of X-ray damaged, genetically incompatible, and heat-killed cells, respectively. This would indicate that the stimulating function may depend on the formation of a proper tumour bed. In addition, a direct " feeder " effect (Puck, Marcus and Cieciura, 1956) may also play a certain role sinice heavily irradiated cells were stimulatory even in the case of freely suspended ascites tumour cells (Revesz, 1955; Scott, 1957; Mazurek and Duplan, 1959). The diffusion chamber technique of Algire, Weaver and Prehn (1954) permits the isolation of the graft from direct contact with host cells. Filter membraines with adequately small pores permit the diffusion of soluble materials but preven

Heat waves in Hungarian plant production

A momentous inference of heat waves is the economic effect. The main demage after the human problems will caused by theeseextreme events in agriculture. For example a long hot peiod without any percipitation can exterminate not only the annual yield, but also itcan demage or in extreme situation it can destroy the whole orchard. Especially endangered most of the fruits, because an extreme summerwith high temperature which usually goes hand in hand with an arid period can modify growth of the plant. Our investigations show thataccording to the most widely accepted climate change scenarios heat waves are expected to be essentially longer and hotter than in the past.It might happen that events we now define as heat waves last through entire summer. Although it will not be general, the length and intensityof present heat waves could also multiply. Based on data provided by some global circulation models, we might be face an event that exceedsthe hottest heat waves of the 20th century by as much as 12 °C. This study also offers a survey of the methodology of heat wave definition.Besides traditional calculations, we present two unconventional methods by introducing minimum and maximum temperature heat waves.Weshow in what points this approach is different from those usually adopted and what extra information it may offer.As an extension of the usualstudies, with considering the length of events, we analyse the development of two variants – temperature and duration – and, as a result,classify the extreme heat events according to both length and intensity

Heat waves in Hungarian plant production

A momentous inference of heat waves is the economic effect. The main demage after the human problems will caused by theese extreme events in agriculture. For example a long hot peiod without any percipitation can exterminate not only the annual yield, but also it can demage or in extreme situation it can destroy the whole orchard. Especially endangered most of the fruits, because an extreme summer with high temperature which usually goes hand in hand with an arid period can modify growth of the plant. Our investigations show that according to the most widely accepted climate change scenarios heat waves are expected to be essentially longer and hotter than in the past. It might happen that events we now define as heat waves last through entire summer. Although it will not be general, the length and intensity of present heat waves could also multiply. Based on data provided by some global circulation models, we might be face an event that exceeds the hottest heat waves of the 20th century by as much as 12 °C. This study also offers a survey of the methodology of heat wave definition. Besides traditional calculations, we present two unconventional methods by introducing minimum and maximum temperature heat waves. We show in what points this approach is different from those usually adopted and what extra information it may offer.As an extension of the usual studies, with considering the length of events, we analyse the development of two variants – temperature and duration – and, as a result, classify the extreme heat events according to both length and intensity

Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy

The magnetization processes in binary magnetic/nonmagnetic amorphous alloy Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic hysteresis loops, temperature dependence of magnetization, relaxation of magnetization and magnetic ac susceptibility, including a nonlinear term. Blocking of magnetic moments at lower temperatures is accompanied with the slow relaxation of magnetization and magnetic hysteresis loops. All of the observed properties are explained with the superparamagnetic behaviour of the single domain magnetic clusters inside the nonmagnetic host, their blocking by the anisotropy barriers and thermal fluctuation over the barriers accompanied by relaxation of magnetization. From magnetic viscosity analysis based on thermal relaxation over the anisotropy barriers it is found out that magnetic clusters occupy the characteristic volume from 25 up to 200 nm3 . The validity of the superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long range magnetic ordering. This work throws more light on magnetic behaviour of other amorphous alloys, too

The maximum modulus of a trigonometric trinomial

Let Lambda be a set of three integers and let C_Lambda be the space of 2pi-periodic functions with spectrum in Lambda endowed with the maximum modulus norm. We isolate the maximum modulus points x of trigonometric trinomials T in C_Lambda and prove that x is unique unless |T| has an axis of symmetry. This permits to compute the exposed and the extreme points of the unit ball of C_Lambda, to describe how the maximum modulus of T varies with respect to the arguments of its Fourier coefficients and to compute the norm of unimodular relative Fourier multipliers on C_Lambda. We obtain in particular the Sidon constant of Lambda

Finite time and asymptotic behaviour of the maximal excursion of a random walk

We evaluate the limit distribution of the maximal excursion of a random walk in any dimension for homogeneous environments and for self-similar supports under the assumption of spherical symmetry. This distribution is obtained in closed form and is an approximation of the exact distribution comparable to that obtained by real space renormalization methods. Then we focus on the early time behaviour of this quantity. The instantaneous diffusion exponent $\nu_n$ exhibits a systematic overshooting of the long time exponent. Exact results are obtained in one dimension up to third order in $n^{-1/2}$. In two dimensions, on a regular lattice and on the Sierpi\'nski gasket we find numerically that the analytic scaling $\nu_n \simeq \nu+A n^{-\nu}$ holds.Comment: 9 pages, 4 figures, accepted J. Phys.

The maximum of the local time of a diffusion process in a drifted Brownian potential

We consider a one-dimensional diffusion process $X$ in a $(-\kappa/2)$-drifted Brownian potential for $\kappa\neq 0$. We are interested in the maximum of its local time, and study its almost sure asymptotic behaviour, which is proved to be different from the behaviour of the maximum local time of the transient random walk in random environment. We also obtain the convergence in law of the maximum local time of $X$ under the annealed law after suitable renormalization when $\kappa \geq 1$. Moreover, we characterize all the upper and lower classes for the hitting times of $X$, in the sense of Paul L\'evy, and provide laws of the iterated logarithm for the diffusion $X$ itself. To this aim, we use annealed technics.Comment: 38 pages, new version, merged with hal-00013040 (arXiv:math/0511053), with some additional result