Showing papers by "ETH Zurich published in 1970"

Local nonsimilarity boundary-layer solutions

Abstract: A new solution method for nonsimilarity boundary layers, applicable locally and independently of information from other stream wise positions, is described and implemented. The governing equations generated by the local nonsimilarity solution method are of the same type as those encountered in the treatment of similarity boundary layers. In addition to its local applicability, the utility of the new method is enhanced by its simplicity and directness, both in concept and in actual computations. Several nonsimilar velocity boundarylayer problems are solved herein with a view to illustrating the method, the participating nonsimilarities stemming from the freestream velocity distribution, surface mass transfer, and transverse curvature. On the basis of comparisons with available published information as well as of comparisons internal to the method itself, it may be concluded that the local nonsimilarity method provides results of high accuracy at all streamwise locations, except those near a point of separation.

Ontogeny and tissue distribution of alcohol dehydrogenase inDrosophila melanogaster.

Abstract: Alcohol dehydrogenase (ADH) activity inDrosophila larvae and adults is localized primarily in fat body, intestine, and Malpighian tubules In adult males, it occurs furthermore in derivatives of the genital disk When expressed as ADH activity/whole organism, increasing values are found throughout the larval stages Around the time of puparium formation, the activity decreases, to increase again around hatching of the adult As the genital disk undergoes metamorphosis, it synthesizes (or activates) ADH rather than acquiring the enzyme from elsewhere in the organism

Vacuolar dynamics in synchronously budding yeast.

Abstract: A simple and rapid method for obtaining synchronously budding cultures of Saccharomyces cerevisiae is described. Synchronous cultures were started with homogeneous cell fractions isolated from exponentially growing cultures by isopycnic centrifugation in osmotically inactive media. The technique of fractionation is based on changes of cell density throughout the budding cycle. These changes are correlated with vacuolar changes observed in the light and electron microscope. During bud initiation the large vacuoles in late budding cells shrink and fragment into small vacuoles. Simultaneously the density of the cells increases. Later stages of the budding cycle are characterized by the distribution of the small vacuoles between mother and daughter cell, followed by their fusion and expansion, and by a decreasing density of the cells. The relative changes in cell density and dry weight and in the content of different macromolecules during the budding cycle suggest a cyclic change between utilization of endogenous and exogenous substrates. This is discussed in terms of a cyclic consumption and accumulation of vacuolar pools.

Photoelectron Spin Polarization and Ferromagnetism of Crystalline and Amorphous Nickel

Abstract: We observe electron spin polarization in photoemission from nickel, undetected in earlier experimental investigations. The saturation electron spin polarization for films prepared on hot substrates is higher than for films on cold substrates and the preferential direction of the magnetic moment is parallel to the magnetization even for electrons excited from energy states near the Fermi level.

Zur Fließbedingung der Plastizitätstheorie

Abstract: In der vorliegenden Arbeit werden einige Aspekte der isotropen und anisotropen Fliesbedingung behandelt. Nach einer kurzen Diskussion uber die Tensorialitat der Materialkonstanten folgt zunachst ein Konvexitatssatz fur die isotrope Fliesflache. Die isotropen Fliesbedingungen von v. Mises und Tresca werden dann auf den Fall ungleicher Zug- und Druckfliesspannungen sowohl fur den inkompressiblen als auch fur den kompressiblen Korper erweitert und diese erweiterten isotropen Fliesbedingungen im ebenen Hauptspannungs-zustand kurz studiert. Die Eigentumlichkeiten der anisotropen Fliesflache im Verhaltnis zu den Drehungen des physikalischen Bezugssystems bilden den Gegenstand der danach folgenden Untersuchung, insbesondere die Richtungsabhangigkeit der Flieseigenschaften einiger speziellen anisotropen Korper. Schlieslich wird eine sinngemase Erweiterung der Trescaschen Fliesbedingung fur den anisotropen Stoff im ebenen Spannungszustand vorgeschlagen.

The effect of pre- and post-trial application of nicotine on the 12 problems of the Hebb-Williams-test in the rat.

Abstract: Pre- and post-trial application of 0.15 mg/kg nicotine had, quantitatively and qualitatively, a very similar effect on the Hebb-Williams-test performance of rats. The performance of both treated groups, was for some of the problems of the second half of the test (composed of 12 problems), better than that of the control group. This result suggests a beneficial effect of nicotine on higher integrative functions. The irregularity of the effect from problem to problem of the test was discussed as a consequence of the structural differences between the problems of the test.

Sloshing frequencies for a half-space with circular or strip-like aperture

Abstract: In der vorliegenden Arbeit werden Naherungswerte (mit stengen Fehlerschranken) hergeleitet fur die Eigenfrequenzen der Schlingerbewegungen einer einen Halbraum mit kreis- oder streifenformiger Offnung ausfullenden idealen Flussigkeit. Das mathematische Modell kann als Grenzfall des klassischen Modells fur endliche Behalter betrachtet werden. Wegen der bekannten Gebietsmonotonie der Eigenwerte sind die Werte fur den Halbraum universelle obere Schranken fur die entsprechenden Eigenwerte beliebiger beschrankter oder unbeschrankter Behalter mit gleichartigen Offnungen.

Crystal-Field Effects and the Anisotropic Magnetization of TmSb

Abstract: We show that the experimental results for the susceptibility and high-field anisotropic magnetization of TmSb can be understood on the basis of crystal-field effects. The absence of any exchange effects is verified by experiments on ${\mathrm{Tm}}_{0.53}$${\mathrm{Y}}_{0.47}$Sb giving the same susceptibility and high-field anisotropic magnetization per Tm ion as in TmSb. The theory and calculation of the anisotropic magnetization are described, and the use of such measurements to determine crystal-field parameters is discussed. Such anisotropic magnetization experiments are particularly valuable in determining the relative importance of fourth- and sixth-order contributions to the crystal field. Analysis of the present susceptibility and high-field magnetization experiments shows that the crystal field is predominantly fourth order, and gives an energy splitting of 26.6\ifmmode^\circ\else\textdegree\fi{}K from the ${\ensuremath{\Gamma}}_{1}$ singlet ground state to the ${\ensuremath{\Gamma}}_{4}$ triplet first excited state of ${\mathrm{Tm}}^{3+}$ in TmSb.

Dirichlet’s divisor problem

Abstract: Let d(n) denote the number of positive divisors of the positive integer n. Let $$E(x) = \sum\limits_{n \leqslant x} {d(n) - x\log x - (2\gamma - 1)x,\,x \geqslant 1}$$ where γ is Euler’s constant. It is known, after Dirichlet, that $$ E(x) = 0({x^{{\frac{1}{2}}}}),\quad as\quad x \to \infty $$

A multiple pendulum for the demonstration of non-linear coupling

Abstract: Es werden Mehrfach-Pendel untersucht, welche Beispiele fur starke quadratische Koppelung liefern. Fur ein Doppelpendel erhalt man die starkste Koppelung, wenn (a) die zwei Drehpunkte auf einer Horizontalen liegen, und wenn (b) die Frequenzen im Verhaltnis 1:2 stehen, wobei zwei Moglichkeiten verwirklicht werden konnen. Die Koppelung manifestiert sich in einem periodischen Energieaustausch; die zugehorige Frequenz ergibt sich proportional zur Amplitude.

Synthesis and X-ray reflection pattern of β-eucryptite

Abstract: f l -Eueryp t i t e (LiA1SiO4) , i m p o r t a n t for the ceramic indus t ry , crystal l izes in t he h i gh qua r t z space g roup P6222 [1?. The s t r uc tu r e is der ivable f rom t he h igh qua r t z s t r uc tu r e [2]. Single c rys ta l p h o t o g r a p h s of ten show weak s u p e r s t r u c t u r e ref lect ions besides t h e m a i n ref lect ions of a h igh quar tz l ike subcell [1, 3, 4]. If t he 3 axes of t h e subcel l are doubled, 3 di f ferent t ypes of ref lect ions can he descr ibed: m a i n ref lect ions h , k , l = 2 n , c-reflections h , k = 2 n , I = 2 n 4 7 1 , a-reflect ions h + k = 2n + 1 or h, k = 2 n + t, I = 2n qt . The i n t ens i t y and t he sha rpnes s of t he s u p e r s t r u c t u r e ref lect ions depend on the c rys ta l l iza t ion condi t ions and t he fu r the r t h e r m a l t r e a t m e n t E3, 4]. f i -Eucryp t i t e single c rys ta l s wi th sha rp aand c-reflections also show some ve ry weak s u p e r s t r u c t u r e ref lect ions wi th l = 2n [4~. 497 and 376, respect ively , i n d e p e n d e n t ma i n and supers t r uc tu r e ref lect ions wi th in tens i t ies u n e q u a l to zero, h a v e been m e a s u r e d on a single c rys ta l d i f f r ac tomete r wi th fi l tered Mo-rad ia t ion in the n o r m a l 0-20-scan. The charac ter i s t ics of t he f l -Eucryp t i t e c rys ta l used were a = 1 0 . 4 9 t 8 ( 3 ) A , c = t1 . t749(7) /~ , chemical compos i t ion Lio.,sAlo.gsSil.oaO 4 and sha rp aand c-reflections. The subcel l ha s served as t he base for t he s t r uc tu r e inves t iga t ion wi th t he m a i n reflections. S ta r t ing with the h igh qua r t z modeI t he following resul ts were ob ta ined : f) R = ~[ F o -F c[ /XF o = 0.055 (anisotropic t e m p e r a t u r e factors, no ex t inc t ion correction). 2) x ( 0 ) = 0.2017(3). 3) The longes t m a i n axis of t he t h e r m a l v ib ra t iona l ellipsoid of t he o x y g e n a t o m s has a l eng th of 0.17 ~*, which is u n u s u a l l y long for silicates. I t is caused b y the \" p r o j e c t i o n \" of t he o x y g e n a t o m s of t he supercel l in to t he subcell. 4) The L i a toms occupy t he a tomic pos i t ion 3a, which m e a n s t h e y are s u r r o u n d e d b y 4 o x y g e n a toms . The supercel l con ta ins 4 s t r uc t u r e channe l s paral lel to c. The resu l t s of the s u p e r s t r u c t u r e inves t iga t ion are: t) ]~mainrefl. = 0.050, Rsuperstr. refl. = 0. t t (isotropic t e m p e r a t u r e factor, no ex t inc t ion correction), T he cor responding s t ruc tu re pa ra me te r s are g iven in t he Table. 2) The Stand M a t o m s are

Proof of an orthogonality principle in irreversible thermodynamics

Abstract: Onsager hat 1931 die Symmetrierelationen formuliert, welche seither die Grundlage der linearen irreversiblen Thermodynamik bilden 1958 hat der Autor diese Relationen als Orthogonalitatsbedingungen auf der Basis der Dissipationsfunktion interpretiert und gezeigt, dass das so erhaltene Orthogonalitatsprinzip (a) im Gegensatz zu den Onsagerschen Beziehungen auch im nichtlinearen Fall sinnvoll bleibt und (b) auf gewisse Extremalprinzipien wie das Prinzip vom Maximum der Dissipationsleistung bzw der spezifischen Entropieproduktion fuhrt

A conforming triangular finite element plate bending solution

Abstract: A conforming plate bending solution using simple polynomial deflection functions of third-degree inside each triangular element is presented In order to avoid normal slope discontinuities along the sides of the elements, the plate displacement parameters are subjected to ‘slope continuity conditions’ acting as constraints to the minimum potential energy problem This is then solved by the classical method of Lagrange introducing multipliers as new auxiliary variables If a special variational formulation of the problem is used, it can be shown that the Lagrangean multipliers are generalized stress parameters The suggested solution is therefore basically a ‘mixed’ solution, the unknown variables of the problem being both displacement and stress parameters Several numerical results are presented

Potassium-argon ages from the Ceneri Zone, Southern Swiss Alps

Abstract: The Ceneri Zone is a unit of the crystalline basement of the Southern Alps. Its northern boundary is the Tonale Line segment of the Periadriatic Line, an important tectonic lineament separating the Oligocene and younger features of the Central Alps from the older metamorphic and structural trends of the Southern Alps. Unmetamorphosed Permian and younger sedimentary units lap onto the Southern Alpine basement from the south.

Chapter 4 Pressure Effects in Superconductors

Abstract: Publisher Summary This chapter focuses on pressure effects in superconductors. The observed effect of pressure on the critical field curve results from a change of superconducting transition temperature, T c , and a change in the molar electronic specific heat constant γ under pressure, and both these effects can be calculated from the observations. There are also closely connected changes in dimensions, elastic constants, and thermal expansion coefficients. The form that the pressure dependence of T c takes under very high pressures is also of current interest, and here there is some controversy as to whether superconductivity can be destroyed by pressure alone without the need for a phase change. Pressure-induced phase changes are found to give rise to abrupt changes in T c, and in a number of cases nonsuperconducting semiconductors are changed to superconducting metals. Quite recently there have been direct measurements of the pressure dependence of the energy gap from tunneling and acoustic attenuation measurements.