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Differential elastic scattering cross sections for electrons in helium have been measured for electron energies of between 100 and 500 eV for angles of between 30 and 150 degrees . The data have been normalized to Bromberg's (1969) measured cross section for 500 eV electrons at 60 degrees . The present measurements are compared with other available data, in particular with the recent work of Crooks and Rudd (1973) and Winters et al (1974).

With the introduction of high-yielding varieties of wheat and other crops during the mid-sixties, the chances of a widespread famine occurring again in India and elsewhere are considerably reduced. The real challenge facing the developing countries during the current and future decades is now recognized as one of providing employment opportunities for all those who want to work. It is also widely recognized now that economic growth does not automatically ensure growth in employment opportunities adequate to match the growth in labor force. The planners in these countries are beginning to realize that plans to utilize human resources must be explicitly considered in evolving the development strategy to be followed. Implicit in this argument is that the development strategy followed hitherto has not done so.

This note describes a simple two-component balance, designed, fabricated, and used by the writers to measure the fluctuations in the horizontal and vertical components of water forces on a sector gate. Details of the two component balance are given. Static calibration curves for horizontal forces in two directions and for vertical forces are presented. The two-component balance described in this note can be used for simultaneous but separate measurement of two mutually perpendicular components of dynamic forces of low frequency and static forces. The capacity, sensitivity, and range of reliable frequencies can be suitably altered by altering the stiffness and mass of the system. The principle can be extended to three component balances also.

Results of observations of ionospheric drift carried out over a period of 15 months at Ahmedabad on 2·6 Mc./s. and 4·0 Mc./s. by the spaced aerial method are presented in this paper. The prevailing day-time drift was towards north-west in autumn and winter. In summer, and to a less marked degree in spring and autumn, the morning direction of drift was towards east or south-east. The evening direction was always towards north-west. During the night hours, the direction of drift were more spreadout, but the most frequent directions were still towards north-west and southeast. The speeds lay mostly in the range 40–100 m./s. and the mean speed was larger in winter than in summer. The Ahmedabad results are compared with those at other places.

Limitations of Fourier analysis are examined and the merits of correlational analysis are discussed. The definition and properties of correlational analysis are studied. The use of correlation functions in the study of (a) the transient response of filters, (b) the spectra of delay modulated signals, (c) the signals in the presence of noise, and (d) the design of linear filters are studied. A typical correlator is described. The limitations of this method of analysis are examined.

The polarizations of representative bands in the 1A2-1A1 systems of H2CO, D2CO, and HDCO are determined by analysis of rotational fine structure of the absorption spectra. In addition to bands of types A, B, and C, there are observed Coriolis couplings about inertial axes a, b, and c. From these identifications the six excited-state fundamental vibrational frequencies are found and confirmed for each molecule: All except the CH stretching frequencies are reduced by at least 25% on electronic excitation. Overtones of the out-of-plane bending mode are discussed in detail. The upper state geometrical parameters obtained from the rotational fine structure are r 0 (CH) = 1.092 A , r 0 (CO) = 1.321 A , ∠HCH = 121.5° and an out-of-plane angle of 20.5°.

The new ultra-violet bands of PO lying in the region 2300–3000 A and degraded to the red, have been excited in a microwave (2450 mc./s.) discharge and photographed in the second and third orders of 3·4 m. and 6·6 m. grating spectrographs. Vibrational analysis of the R1 and Q2 heads shows that they can be expressed by the relation $$v_h = \left. \matrix{ 43852 \cdot 43 \hfill \cr 628 \cdot 60 \hfill \cr} \right\}\matrix{ { + 826 \cdot 37 (v' + \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} ) - 6 \cdot 96 (v' + \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} )^2 } \cr { - \left\{ {1233 \cdot 38 (v'' + \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} ) - 6 \cdot 56 (v'' + \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} )^2 } \right\}.} \cr } $$ . Rotational analysis of the 0–2 and 0–3 bands shows that they arise out of a2 Σ −−X2 Π transition.

The cross section sigma /sub I/( epsilon ;E) has been calculated for the direct impact-ionization of hydrogen atoms by protons, H/sup +/ + H(1s) yields 2H+ + e/sup -/, for low relative collision energies E between l00 and 500 eV, and all electron energies epsilon for which it is significant. Fundamental theory and most electronic matrix-element calculations were presented in earlier papers of the series. In the present paper we complete the electronic matrix- element calculations (in particular, thc -'optimization'' of Coriolis or angnlar coupling matrix elements for ionizing transitions, through introduction of an angular velocity electron-translation factor); and we perform the final integrations over classical trajectories and impact parameters to obtain the cross sections. The cross sections epsilon /I/( epsilon ; E) show the expected steep falloff with increasing epsilon and decreasing E, owing to the increasing inefficiency of momentum and energy transfer from the heavy particles to the electron under such changes; epsilon /sub I/ decreases by about two orders of magnitude from E = 500 eV to E = l.0 eV, and by four orders of magnitude from epsilon = 0 a.u. to epsilon = l.0 a.u. A strong dependence of cross section on isotopic mass atmore » fixed E is also predicted thereby. Finally, the most significant conclusion is that the cross section for ionization from the 1s sigma /sub u/(2p sigma /sub u) molecular electronic state is about 500 times greater than that for ionizing a 1s sigma /sup g/ molecular electron, the main source of transitons being the Coriolis coupling operator. (auth)« less

Interactions of vibrations through rotation about the principal axes of the molecule, and anharmonic resonance interactions were found to explain satisfactorily almost all the rotational level perturbations observed in the vibronic states of the H 2 CO, D 2 CO, and HDCO molecules. The basis for these explanations was found in model calculations for perturbations in vibrotors of asymmetries and inertial parameters appropriate for formaldehydes. The most important result that emerged is that it can be difficult to distinguish a -axis Coriolis and Fermi resonances, and b - and c -axis Coriolis resonances from each other unless intensity as well as energy perturbations are analyzed. Strong coupling of the levels ν 4 and ν 6 in the ground state of HDCO, through rotation about the a -axis was analyzed exactly to determine the inertial constants of the two states, the coupling parameter and the difference in vibrational energy levels. There is appended a set of graphs which make it possible to estimate for a given a -axis Coriolis resonance in an asymmetric rotor whether the relatively simple symmetric top energy expression will be adequate for band analysis.

The method of determining all the possible cut sets of a graph by the linear combination of the rows of the incident matrix of the graph is examined. The conditions to be satisfied for such combinations to yield cut sets are determined. The maximum number of branches that would constitute a cut set of a graph is found out.

The historical background and the methods of fixed interval analysis and fractile analysis are presented in this exposition. Two methods of comparing certain aspects of two bivariate distributions rather than their regression functions are described in Section 1. It often happens that this is very meaningful in certain practical situations. The large sample theory of some statistics that enter this discussion is presented in Sections 3, 4 and 5. Some historical notes about these methods are related in Section 6. A few tables that can be used for testing purposes when the underlying distributions are bivariate normal are given in Section 7.