Results Of Brown Research Articles

Summable chains of instantons: Green's functions and the Prasad-Sommerfield limit

We construct, for each homotopy class, a type of instanton configuration which exhibits many special, simple properties. The basic reason behind such properties is indicated by deriving our configuration in the 't Hooft gauge, starting from a class of particularly simple, static, and self-dual solutions in de Sitter space. Apart from this we consider, in this paper, mostly results for flat Euclidean space. We show that the static solutions are equivalent to multiply charged instantons at the origin in Witten's sense. Green's functions for this class of instanton background are studied. The known flat-space results of Brown et al. are shown to be reducible, for our case, to totally explicit and relatively compact forms. The sums over different indices arising in their formalism are performed. The inversion of a matrix, necessary for the isospin-1 massless scalar field, is carried out explicitly, for our configuration, for arbitrary index of the background instanton field. Green's functions for the Prasad-Sommerfield case are obtained as limits of our results directly in summed-up forms. Green's functions are studied also in de Sitter space. Special features due to periodic time are pointed out.

The main problem of lunar theory solved by the method of Brown

Brown's method for solving the main problem of lunar theory has been adapted for the computation by machine with the help of an algebraic processor. Brown's results are first recovered and refined. The solution is then expanded to include most terms of order nine. The terms in the series for the longitude and latitude are listed with an accuracy of 0.000 01“ and of 0.000 001” for the parallax.

A note on two papers by Kuntsevich & Belov

1237 four-dimensional space-group types of the 'low-symmetry crystal classes' have been listed by Kuntsevich & Belov [Kristallografiya (1971). 16, 5-17, 268-272]. Comparison of this list with the results of Brown, Bulow, Neubuser, Wondratschek, and Zassenhaus shows that three space-group types are listed twice and one space-group type is missing. The crystal classes considered by Kuntsevich & Belov thus contain 1235 of the 4783 types of space groups of R4.

Many-body theory for simultaneous photoionization and photoexcitation of helium

Abstract Brueckner-Goldstone many-body perturbation theory is applied to study the simultaneous photoionization and photoexcitation (SSP) of helium. The results are used to examine the validity and limitations of other approaches to the problem. The oscillator strengths ( d ƒ ϵ ) for the transition 1s2→(2s ϵp)1P and 1s2→(2p ϵs)1P are compared with the results of Brown. The cross section for SPP at the photoexcitation threshold (65.399 eV) is found to be in agreement with the experimental result of Samson.

Orientation of galaxies and a magnetic ?urfield?

Brown's results (1964, 1968) concerning the distribution of orientation angles of spiral galaxies in different areas of the sky are discussed and a graphical statistical test is applied. The deviations from randomness are found to be significant. It seems difficult to ascribe them to selection effects. It is shown that the observed distributions can be explained, if the angular momenta in greater aggregations of galaxies are distributed at random on congruent precession cones with parallel axes. This hypothesis may apply if the following cosmological conditions hold: For a rigid body approximation the equations of motion are derived and solved numerically. Approximate analytic solutions are also given. The precession period is in the range of 104 to 108 yr for plausible values of the parameters of the problem. The observed distributions in the four regions of the sky investigated are — via the precession hypothesis — compatible with a direction of the ‘urfield’ indicated by the work of Sofueet al. (1969) and Reinhardt and Thiel (1970) ofl II≈280°,b II≈+30° tol II≈100°,b II≈−30°.

On the application of current algebras to nonleptonic hyperon decays

Current algebras applied to nonleptonic hyperon decays lead top-wave amplitudes of about one-half of the experimental values and to worse values ofB(σ++). With new experimental data the results of Brown and Sommerfield become worse forp-wave amplitudes, in particular forB(σ++). In the present note we try to correct this situation by taking into account theSU3-breaking effect in estimating the equal-time commutator term forp-waves from the K10→2π decay amplitude which is alsoSU3-violating. Fits to boths andp-waves are made without assumingSU3. The results are somewhat improved.

Scattering of a High-Intensity, Low-Frequency Electromagnetic Wave by an Unbound Electron

Thomson scattering of a high-intensity, low-frequency, circularly-polarized electromagnetic wave by a free electron is considered. We find that by neglecting radiative corrections and pair effects, the Feynman-Dyson perturbation expansion is summable, and the sum can be analytically continued in the form of a sum of continued fractions. By imposing the boundary conditions that at $t=\ifmmode\pm\else\textpm\fi{}\ensuremath{\infty}$ the photons and target electron propagate as free particles, we obtain results which differ from those reported by Brown and Kibble and by Goldman. In particular our results differ in two aspects. The first difference is in the kinematics; namely, we find no intensity-dependent frequency shift in the scattered photon. The second difference is in the dynamics; that is, we obtain a different expression for the scattering amplitude. Both of these changes originate in the choice of boundary conditions. Instead of treating the asymptotic radiation field classically, we choose our states as linear combinations of occupation-number states. Finally, contact is made with the results of Brown and Kibble and of Goldman using a mixed set of classical and quantum boundary values.

Note concerning an equation in E. W. Brown's Lunar Theory

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Note concerning an equation in E. W. Brown's Lunar Theory Pilet, Stanford C. Abstract A correction is made to two equations published by E. W. Brown in an early investigation on the elliptic inequalities in the lunar theory. Independent calculation shows typographical errors in these equations, but Brown's results prove that he used the correct equations in his calculations. Publication: The Astronomical Journal Pub Date: March 1963 DOI: 10.1086/108929 Bibcode: 1963AJ.....68..123P full text sources ADS |

Photodisintegration of calcium

Abstract Photoproton spectra of calcium have been recorded at bremsstrahlung maximum energies of 19.5 and 20.5 MeV. By subtraction a proton spectrum corresponding to photon absorption in the range 20±0.5 MeV was obtained. The proton spectra show well resolved peaks corresponding to transitions to the ground state and excited states at 2.9 MeV and 5.9 MeV. These states are assumed to be the single particle hole states in K39 with spin values d 3 2 , s 1 2 and d 5 2 . These assignments are supported by a comparison of experimental branching ratios and angular distributions with theoretical values calculated on the basis of the results of Brown et al.

A comparison of two gonadotrophic extracts, PMS and HCG, with a critical examination of assay procedure.

SUMMARY The method of assay for gonadotrophin developed by Claringbold & Lamond (1957) has been found satisfactory and suitable for a wide range of management conditions and strains of mice. It has been confirmed that this method gives similar slopes for human chorionic gonadotrophin and pregnant mares' serum and it has been found, in addition, that these slopes do not differ from strain to strain. An explanation is offered of the contrary results of Brown, Cunningham & Finegan (1959) and some comments are made on the design and analysis of assays, particularly the selection of dose ranges. It is considered that the uterine weight assay offers no evidence for the existence of two separate gonadotrophic principles.

Apparent Thermal Conductivity of a Heterogeneous Ceramic Body Under Isothermal Conditions

USING statistical arguments, Brown1 derived expressions for the apparent permittivity of a binary mixture of solid phases in terms of the volume fractions and the permittivitits of each phase. The purpose of the present note is to direct the attention of experimentalists working on heat‐transfer phenomena in ceramics to the fact that simple extensions of Brown's results will yield equations for the apparent thermal conductivity of a heterogeneow ceramic body at constant temperature, whether the heterogeneity arises from the existence of isometric pores in an otherwise homogeneous solid or as a result of two solid phases being present. It is demonstrated below that the averaging formula for the apparent thermal conductivity of a porous ceramic body derived by Loeb,2 and employed by Francl and Kingery, 2 is a consequence of terminating series expansions for the thermal conductivity after the fist term. Brown's generalized result is given by where, for the dielectric case, KO is the ratio of the polarization to the Lorentz field intensity and K is the ratio of averaged values of these quantities, A is the shape factor for the particles of the minor phase in a binary mixture, and VA is the volume fraction of that phase.

Internal consistency of the Heisenberg-Dirac model for antiferromagnetism

An attempt is made to investigate the internal consistency of the Heisenberg-Dirac model for antiferromagnets with nearest-neighbor interactions only. The Bethe-Peierls-Weiss approximation and the results of Brown and Luttinger are used to obtain relations between the Néel temperature and the exchange integral, J, and between the susceptibility at the Néel temperature and J. By combining these relations with experimental values of T N and X( T N ) for a given compound, two distinct values of J can be deduced. These values should agree if the theory is internally consistent. Comparisons have been made with experimental data on six antiferromagnetic compounds which seem to satisfy the nearest-neighbors-only restriction. The agreement is about as good as could be expected, considering the estimated experimental error. Approximate values of ¦ J¦/ k deduced for the compounds MnF 2, FeF 2, LaFeO 3, LaCrO 3, KFeF 3 and KCoF 3 are 1.8, 3.0, 27, 28, 6.0 and 12°K, respectively.

現象的速度に關する研究 (第1報告)

§1. Studies of the so-called ‘constancy’ of visual velocity have originally been made by J. F. Brown (19 8, 1931), and followed by J. Ogasawara (1938) and H. Wallach (1939). Brown performed experiments on this phenomenon on the assumption that if the constancy of velocity was a mere consequence of that of size, velocity ought to be quite as constant as size is. His results however designated that the constancy of speed was more reduced than that of size at the same distance, and he concluded that the former could not be deduced from the latter. Ogasawara, on the other hand, finding from his experimental results that speed constancy was considerably reduced with the decrease of the inhomogeneity of the moving field indicated that as this was the common feature of all other constancy phenomena, speed constancy must rest on the same psychophysical bases as other common constancy phenomena are. As for Wallach he came to the conclusion theoretically that speed constancy could be explained with no reference to the constancy of visual size but by the ‘transposition principles’ (in Brown's sense) alone, if those principles were applied to retinal images and displacements.§2. Let us discuss on the above three theories. Brown's outcome that speed constancy is more reduced than size constancy is inconsistent with Ogasawara's in which the former constancy is either the same as or even larger than the latter. But the assertion of Ogasawara does not seem valid partly because his experimental set-up is incomplete and partly because it conflicts with Brown's results, in which the constancy of speed does not differ when the experiment is conducted in the dark room from when performed in the light room. I tried a series of experiments in order to examine this point. Both experiments on speed constancy and on size constancy were performed under the same conditions (the same objects subjects, distances, etc.) both in the highly articulated and less articulated visual fields. Table I shows the results of three subjects. The figures represent constancy indices computed by Brunswik's logarithmic formula.Table ISIZE CONSTANCYSPEED CONSTANCY(a) under the heterogeneous conditions in the light room.(b) under the less heterogeneous conditions in the light room.It can be stated from the table that size constancy is greatly influenced by the field condition, whereas speed constancy is not, though both experiments were tried under the same situations. I performed further experiments in order to find any relationship between speed constancy, on one hand, and the distance and the visul field on the other hand. The results lead to conclude that (1) even in the case of the completely dark room and of the monocular observation, constancy indices are nearly 1 ranging from .94 to .89, (2) the homogeneity of the moving field, however, reduces speed constancy just a little and (3) constancy indices have no correlation to distance, but visual speed is decreased with distance. This leads me to question the validity of Qgasawara's conclusion.Though quite plausible Wallach's theory is, stating that the phenomena of speed constancy and the ‘transposition’ of visual speed are the same on the retina, how can it explain the fact that while speed constancy is greater in the daylight illumination, the transposition principles are impaired under the same conditions?§3. Suppose the two moving fields A and B are set at 1m and 10m distance respectively in front of the observer in a completely dark room and B is seen, ceteris parlbus, as nearly a tenth of A in size and both are seen on the same frontal parallel plane. This situation is phenomenally nothing but that in which two objects A′ and B′ in the relation of B′=1/10A′ are placed equidistant. Therefore if we assume that the transposition principles work with reference to the phenomenal variables, we must