Topmost Level Research Articles

Overshoot of quantum Hall plateaus

In magnetoresistance studies of high mobility GaAs/AlGaAs Hall bars in the quantum Hall regime we observe that the Hall resistance ( R H) overshoots the normally observed spin plateaus; however, as the magnetic field is further increased, R H, decreases until a plateau is formed at ( 1 N odd ) h e 2 . The resultant peaks in R H occur only on the low magnetic field e plateaus and show both a strong temperature and sample geometry dependence. These anomalies are due to a decoupling with magnetic field of the two edge states associated with the topmost spin split Landau level. This decoupling occurs rapidly because of the enhancement of the spin splitting due to electron-electron interactions.

Upper Boundary Effects in a General Circulation Model

The effects of an artificial upper boundary on the climate of a general circulation model are examined using two versions of the model. The complete model has 26 levels extending from the surface to 0.1 mb (∼65 km) and the second version approximates the usual tropospheric general circulation model, having 15 levels extending to 10 mb (∼30 km). The two model versions are identical over the common part of the domain. Vertically propagating Kelvin waves are found in the tropics of both versions of the model. In the version extending only to 10 mb, the Kelvin waves are reflected by the top boundary, and resemble standing oscillations in the vertical. while retaining (approximately) their original zonal phase speed. Some of these reflected waves develop much larger lower stratospheric amplitudes than when they are able to propagate freely into the mesosphere. Placing the topmost model level at 10 mb is found to radically alter the winter stratospheric circulation and to produce significant changes in the tropospheric circulation. Stationary planetary waves are reflected off the model's top boundary and become approximately equivalent barotropic in the stratosphere, with no vertical phase tilt and reduced meridional phase tilt. The altered planetary waves have larger geopotential amplitude but produce very small poleward fluxes of heat. The stationary planetary wave amplitudes in the troposphere are not strongly affected by the changed upper boundary, but the phase structures are quite different. A third experiment was performed in which the zonal mean wind was controlled directly through an additional Rayleigh friction term. The results of this experiment indicate that the tropospheric stationary planetary wave structure responds to the mean flow structure of the lower stratosphere, rather than directly to the presence of a top boundary.

Connected Component Labelling using Quadtrees - A Bottom-up Approach

An algorithm to label the connected components of a binary picture is presented using a hierarchical version of the linear quadtree. This algorithm, which starts from the lowest level of the hierarchy, is shown to be computationally faster than the one using the topmost level as the starting point. The computational complexity of the algorithm appears comparable to that of existing methods due to Gargantini and Samet.

Aspects of library and information services in the framework of social policy planning

It is no longer seriously doubted that the economic development of any country depends directly on the availability of information services for the support of industry and technology. To help with their establishment, several basic guides are now available-e.g. J. H. d’Olier’s,l and the series issued by the O.A.S.s-to explain their theory and practice, but though these deal with a great many statistical and conceptual issues underlying the establishment of information services and data stores, they do not wholly pre-empt the field. Certain aspects are of necessity touched upon only briefly and there appears to be scope for further comment. A closely related problem, the transfer of knowledge, was also the basic theme at a symposium held in Vina de1 Mar in 1975;s indeed this subject has been at the core of hundreds of learned contributions to what is now called information science. Nevertheless, lip service has rarely been matched by actual government support for this basic public utility and it has been rare for information services to be given the high priority they deserve in any economic growth programme. I shall restrict myself, in this context, to societies which in spite of their industrial underdevelopment, have attained a degree of general literacy, so that it can be assumed that the printed word is an established means of communication among a high percentage of their population. In such societies, the failure to accord a high priority to information and library services would seem to arise from a lack of understanding, at the topmost level of government, of the benefits and indeed the fundamental

Monte Carlo trajectory study of Ar+H2 collisions. II. Vibrational and rotational enhancement of cross sections for dissociation

Integral cross sections and properties of the dissociated trajectories were calculated for the reactions Ar+H2→Ar+H+H and Ar+H2(qb) →Ar+H+H, where H2(qb) is a quasibound H2. Integral cross sections were also calculated for Ar+H2?Ar+H2(qb). Twenty-four different (21 bound, 3 quasibound) initial vibrational–rotational states of H2 are considered. The potential surface (which we presented previously) is based on modified statistical calculations at small distances and dissociates to an accurate potential in the van der Waals region and to accurate diatomic curves. At a total energy 1 eV above the energetic threshold for dissociation, we find reagent vibrational energy is very effective in promoting dissociation (the vibrational bias parameter of Kiefer, Joosten, and Breshears is about 11 to 13), rotational energy is second most effective, and relative translational energy is least effective. Except for the topmost vibrational level we find dissociation cross sections are much smaller than predicted by the hard-sphere available-energy theory.

Elliptic Curve Scalar Point Multiplication Algorithm Using Radix-4 Booth’s Algorithm

The main back-bone operation in elliptic curve cryptosystems is scalar point multiplication. The most frequently used method implementing the scalar point multiplication, which is performed in the topmost level of GF multiplication and GF division, has been the double-and-add algorithm, which is being recently challenged by NAF (Non-Adjacent Format) algorithm. In this paper, we propose a more efficient and novel approach of a scalar multiplication method than the double-and-add by applying redundant recoding which originates from the radix-4 modified Booth’s algorithm. We call the novel algorithm quad-and-add. After deriving the algorithm, we created a new GF operation, named point quadruple, and verified with calculations of a real-world application to utilize it. Derived numerical expressions were verified using both C programs and HDL (Hardware Description Language). Proposed method of elliptic curve scalar point multiplication can be utilized in many elliptic curve security applications for handling efficient and fast calculations.

On My So-called Nucleus Calami Scriptorii, Nucleus Rotundus and Nuclei Dorsales Macrocellularis et Microcellularis in Human Adults

At the position corresponding to the subependymal layer of the calamus scriptorius, I have found a nucleus which I propose to call the nucleus calami scriptorii. This nucleus contains in its loosely arranged glial tissue small nerve cells and, especially in pits medial parts, some larger melanin pigment cells, both with very fine axis cylinders which, forming small bundlets, run through the undermentioned nuclei rotundus and dorsalis microcellularis, to pass over into the fine vegetativa fibres in the tractus solitarius. This nucleus becomes gradually worse developed as the fossa rhomboidea passes over into the canalis centralis. It is first located on the dorsal side of the canalis and its right and left halves are bounded by a narrow raphe of glial tissue, but soon they become fused in one. Some decussating bundlets are demonstrable therein.In a transverse section of the brain stem at the height of the obex, we see a broad band of grey substance dorsal to the nucleus hypoglossus and between the snbependymal layer and the nucleus calami scriptorii on the one hand and the tractus solitaruis on the other, half-surrounding this tract on the dorsomedial side. This band has been long named the nucleus dorsalis. In this nucleus, however, I could distinguish a group of large nerve cells on the dorsal side of the hypoglossal nucleus and extending from the dorsomedial to the ventrolateral, which I propose to name the nucleus dorsalis macrocellularis. The number of the large nerve cells in this group averages 25 in a transverse section on the level of the obex and decreases thence caudalwards, falling to nought on a level somewhat below the caudal end of the hypoglossal nucleus. Upon reaching a level more cranial to the obex, it begins to move to a more dorsal position, and when the ala cinerea comes into view, it takes up a position dorsomedial-ventrolaterally bridging the hypoglossal nucleus and the solitary tract, on the lateral side of the subependymal layer in this part and here the cells number from 35 to 45. At the topmost level of the calamus scriptorius, the group attains the maximum development and consists of 65-75 nerve cells in one section. But ascending further to the fevel where the ala cinerea begins to narrow down, its development also falls off, and when the nucleus triangularis begins to protrude into the fossa rhomboidea, the nerve cells begin to move into the deeper parts. They come into contact with the formatio reticularis midway between the tractus solitarius and the hypoglossal nucleus here and soon are lost sight of altogether. Near the end of this group, many thick motor fibres from the nucleus ambiguus are found meandering among the now extremely decreased nerve cells. The level where this nucleus ends cranially is somewhat higher than the cranial end of the nucleus hypoglossus and somewhat lower than that of the tractus solitarius.A small number of small nerve cells is also contained in the nucleus dorsalis macrocellularis. Its large cells are larger in thigher than the lower parts and larger in the dorsal than in the ventral parts. These are, however, always smaller than somato-motor cells, and are different from the latter in form too, showing rounded, and not the rugged contour of the latter. They are variously shaped spindle-like, round, oval, or polygonal. Their intracellular nerve fibrils are very fine and only weakly stainable, and this characteristic also, coupled with the comparatively large size of their nuclei, serves in distinguishing them from sensory and somato-motor cells, and clearly indicates that they are of vegetative nature. The small nerve cells are only smaller in size, but are of the same nature too.The dendrites of the nerve cells, and especially those of the large cells, are thick and long and seem to end in sharp points after ramification. Accompanying these cells and their dendrites, we often find fine but strongly stainable nerve fibres.

Changes in Potato Root Eelworm Population with Time and Depth

By growing potatoes in infested soil in sectional wooden boxes, changes in the population of potato root eelworm have been observed at 5, 9, 13 and 19 weeks after planting, and at 5 two-inch levels in the soil. Results show that most of the increase in population occurred during the last 6 weeks of the experiment and that the normal population changes proceeded more slowly in the topmost level, leading to a lower final population in that level.

Archaeological Horizons in Central California

ARCHAEOLOGICAL HORIZONS IN CENTRAL CALIFORNIA By ROBERT F. HEIZER and FRANKLIN FENENGA INTRODUCTION present to the archaeological T HE the lower paper is an attempt The define of this discussion is situation in Sacramento Valley. aim to sum­ marize a threefold culture sequence called here Early, Middle and Late, and to place it within the general scheme of California prehistory as we understand it at the present time. Until quite recently California culture has been widely cited as endowed with an unique uniformity and unchange­ ableness, persisting in its simple, specific form for thousands of years. We now know this to be incorrect. Wherever intensive, planned archaeological work has been prosecuted in California, cultural differences have obtruded themselves. 1 Our type section and largest sampling is from the Mokelumne-Cosumnes river region, with additional data from the upper Sacramento valley (site 1) and the Sacramento-San Joaquin river Delta region (sites 138, 139). The Cosumnes river sites are 107,6, 120, 126, 127; the Mokelumne river sites 68, 66, 142. Site 60 on the Sacramento river is geographically intermediate as is site 99 on the lower American river. Map 1 shows the location of these sites. 2 Schenck and Dawson published, in 1929, a volume on the archaeology of the northern San Joaquin valley.3 They concluded that in this region (called Stockton-Lodi), certain sites could be differentiated by character­ istic cultural forms, and that these cultural divergences reflected temporal differences. But Schenck was very hesitant in offering this interpretation, and when in 1933 the Sacramento Junior College instituted an archaeolog­ ical program under the direction of President J. B. Lillard, it was with the main idea of gaining a general insight into the archaeology of their area, and not of a specific search for cultural sequence. Two Cosumnes river sites (126, 127) yielding the same culture were successively investigated. The third, site 107,4 soon showed itself to be stratified, the topmost level agreeing with the culture disclosed in sites 126 and 127, the bottom level something entirely different. Intermediate in this site between these two divergent cultures was a manifestation apparently of a transitional phase. In 1936 Lillard and Purves published a bulletin on the basis of this trio I See Rogers, M. 1929; Olson, 1930; Rogers, D.B. 1929. • See Schenck. and Dawson (1929; 293-305) for a good geographical description of the area. I Schenck and Dawson, 1929. , Lillard's sites 1, 2, and 3 are respectively our 127, 126, 107.