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Crude extracts ofPhysarum polycephalum contain five DNA degrading enzyme activities. One enzyme activity degrades native DNA with a maximum activity at pH 3.2. Four others degrade heat-denatured DNA and have their maximum activity at pH's 3.4, 4.0, 7.6 and 8.5 respectively. The five DNA degrading activities react in different ways to administration of divalent cations and show different stabilities towards heat inactivation or incubation conditions.

The properties of the positive column of strongly modulated low-pressure gas discharges in mercury-rare gas mixtures have been studied, both experimentally and theoretically. The current was modulated sinusoidally with a modulation depth of 50%. Calculations have shown that in a limited frequency range nonlinearities in the system have an effect on the time-averaged electron temperature, electron density and excited atom density, and on their waveforms. This behaviour was confirmed by experiments, in which the electron temperature and density were measured by means of microwave techniques and the excited Hg atom densities by measuring the optical absorption and emission. For higher modulation depths differences occur between the results of the calculations and experiments. These discrepancies were found to be more pronounced in pulsed discharges, and are ascribed to changes in the high-energy tail of the electron velocity distribution function.

A new method for analysis of double probe characteristics is developed. These characteristics are recorded on punch tape, and their data are fed into a computer, which calculates both electron temperature and plasma density. Several methods of analysis of the characteristics in low pressure plasmas are compared. The determination of electron temperatures appears to be of good accuracy (10%). On the contrary, the absolute plasma density can only be determined roughly. For relative density measurements the probe technique gives satisfactory results.

The computation method described in this paper is based on the existence of a linear relationship between the mutual coupling ratio and the kernel function in the integral expression for it. Accordingly, the mutual coupling ratio can be determined by first computing sample values of the kernel function and then subjecting these to a digital linear filter. In the present paper the appropriate sampling distance is determined and the values of the digital filter coefficients are computed, both for electromagnetic sounding with horizontal coils and for electromagnetic sounding with perpendicular coils.

After the discussion of a number of publications concerning congenital deformities mention is made of two groups of families containing children with anencephaly, spina bifida, encephalocele and other deformities involving an abnormal development of the central nervous system and the surrounding supporting tissue; one group has been collected in accordance with the period of birth, the other with the birth-place; together the groups comprise 181 families.

The electron temperature decay in the afterglow of Hg–Ne and Hg–Ar low‐pressure gas discharges has been investigated, both experimentally and theoretically. The temperature decay is not only determined by elastic losses but also by collisions of the first and second kind with excited Hg atoms. Collisions of the second kind have a heating effect on the electron gas and our results show that the energy relaxation time may increase by a factor of 10 by this process. Reasonable agreement has been obtained between the experimental data and the results of calculations which take the above processes into account. The electron temperature has been determined by means of 1.5‐GHz noise measurements, the Hg (63P) densities by means of optical line absorption.

Results of an experimental investigation of the velocity profile of a turbulent gas injected in a toroidal configuration are presented. The measurements surprisingly show that it is possible to describe the radial distribution of the azimuthal velocity in terms of a plane wall jet discharging in an external stream.

Some results of double probe measurements on electron temperatures in a radio frequency hydrogen discharge (pressure 0.02–0.07 torr) are reported. The probe characteristics, recorded on punch tape, were analysed by means of a computer. A reasonable agreement between experimental values of the temperature and those calculated with aid of a modified Schottky theory was found.

Es wird gezeigt, das bei der komplexometrischen Titration von Calcium bei pH 12,2 zum visuellen Endpunkt des Mischindicators von Calcein und Thymolphthalein [4] das Barium quantitativ mittitriert wird. Eine verbesserte Methode wird nun fur die Bestimmung von sowohl Calcium als auch Barium in 50% igen Atznatronlosungen beschrieben. Nach einer Vortrennung und Anreicherung durch Ionenaustausch wird die Summe von Calcium und Barium durch Titration mit ADTA-Losung bei pH 12,2 bestimmt. Barium wird dann durch Sulfat aus dem ADTA-Komplex freigesetzt und die aquivalente Menge ADTA durch Zugabe einer bekannten Menge Calcium im Uberschus und Titration des Uberschusses mit ADTA bestimmt.

Benzophenone and 4, 4′-dimethylbenzophenone are added photochemically to 1-methoxy-1-propyne. Besides methyl 3, 3-diarylacrylates I, the alkylidenecycloheptatrienes II E and II Z are isolated.

Results of a theoretical study of the positive column of a Hg-Ar discharge sustained by an AC current with a sinusoidal waveform (pAr=3 Torr, pHg=6×10−3 Torr, R=1·8 cm, Ieff=0·4-0·55 A) show a decrease in efficiency for UV emission with increasing supply frequency f for f 500 Hz. The efficiency can be slightly higher than the DC efficiency for a properly chosen frequency (fgreater, similar10 kHz). A comparison with experimental results, available in the literature for comparable discharges, is made, indicating a qualitative agreement. In addition, the temporal behaviour of a number of plasma quantities is presented for various supply frequencies.

Using as a diluent a veronal buffer with Mg and Ca ions a wide range of concentrations of hemolytic antibody, prepared according to the prescription of the New York State Department of Health, could sensitize different lots of Alsever preserved sheep red cells to the same maximal degree.

The time-dependent Boltzmann equation for electrons in a weakly ionized plasma, subject to a suddenly applied electric field, has been solved numerically. The solution gives the relaxation of the electron velocity distribution towards the equilibrium, belonging to the value of E . It is found that the number of electrons in the tail of the distribution is larger during the heating process than in a steady state with the same average energy. This is caused by a forced drift in velocity space and increases the rate of excitation of atomic levels (up to a factor of 10, depending on the parameters used). The results of the computations may play a role in the explanation of the enhancement of the light emission by pulsing a low-pressure arc discharge with a period between the diffusion time and the energy relaxation time of the electrons.

A Group Life and Pension Scheme is an employer's scheme instituted for the benefit of his employees. The real position of the life office, which is usually responsible for arranging the scheme, is that of underwriter. From the life office's point of view, with which this paper is solely concerned, the guaranteeing of these schemes on a group basis, as opposed to issuing an individual policy on the life of each employee, is a special class of business with certain definite characteristics which have not changed very much since N. C. Turner presented his paper to the Students' Society in 1930 on the subject of Group Insurance and Group Pension Schemes.

1. When spinach chloroplasts are isolated in media containing high concentrations of NaCl, monogalactolipase activity can be observed. In media containing sucrose or mannitol, there is also an enzymatic transacylation which results in a decrease in digalactolipid and the formation of acylated derivatives of the mono- and digalactolipids. The rate of release of free fatty acids is slower under the latter conditions. 2. In order to establish a relation between these phenomena and the photochemical capacities of the chloroplasts, several light reactions have been measured in fresh and aged chloroplasts. 3. Hill reactions in Photosystem II and NADP + reduction in Photosystem I are not directly influenced by the lipid transformations. 4. Photophosphorylation and Hill reaction at limiting light intensities are very labile under the experimental conditions. Lipid transformations may contribute to this effect. 5. Serum albumin has no effect on the transformations of chloroplast galactolipids. It has a stimulating and stabilizing effect on photophosphorylation and improves the efficiency of photophosphorylation. Only a part of this effect can be explained by the known capacity of serum albumin to bind free fatty acids.

Measurements of the noise temperature in the L band were used to investigate the effect of several constituents of the gas mixture on the discharge properties of the CO 2 laser. Addition of He and H 2 O to the discharge gives no significant change in the temperature. By contrast, addition of 4-torr N 2 to 2-torr CO 2 increases the noise temperature from 1.3 to 1.5 eV. Increase of the current in an optimum CO 2 -N 2 -He-H 2 O mixture leaves the temperature nearly constant (1.5 eV). This result deviates from that of Tyte and Sage, who found an anomalous rise of noise temperature with increasing current. Within the 5 percent experimental error the radiation temperature does not depend on laser action. A comparison of the present results with those of probe measurements is given. It is concluded that He has practically no influence on the average electron energy, which in turn controls the vibrational excitation. This and the observed behavior of the output power as a function of the partial He pressure give strong evidence that the major role played by He is cooling the gas in the discharge.

Baak J.-C., Van Panhuys Polman Gruys P. Les deux barons de Heeckeren : documents néerlandais publiés par J. G. Baak et P. van Paniiuys Polman Gruys. In: Revue des études slaves, tome 17, fascicule 1-2, 1937. pp. 18-45.

The longitudinal electric field and the electron density and temperature have been measured in the positive column of low‐pressure dc arc discharges in mixtures of cesium and argon at densities around 5×1018 and 5×1022 m−3, respectively. The measurements have been made with electrostatic probes and with a microwave interferometer. At a low discharge current cesium alone is ionized. When the discharge current is increased the cesium atom density is reduced by ionization and radial diffusion, and at a critical current a discontinuous transition to a state having a high electron temperature is observed. This discontinuity is explained as the result of a multivaluedness of the electric field as a function of the current density. Even at the present low degree of ionization the electron mobility is found to be strongly influenced by Coulomb collisions.

A 4 mm microwave interferometer has been developed for measurements on electron concentrations in low‐density plasmas (ne≥1010 cm−3). The microwaves are transmitted via Lecher wires, inserted across the discharge tube, to obtain high spatial resolution (≲one wavelength). The sensitivity of the system is improved by eliminating the influence of possible variations in the klystron frequency. A microwave phase shift as low as 2π×10−3 rad can be detected in this way. Density oscillations can be scanned by means of a sampling technique. An example of applications on low‐pressure arc discharges is given.