Previous Picture Research Articles

Solitary-wave velocity selection in self-induced transparency.

We consider self-induced transparency beyond the slowly varying envelope approximation. For a carrier wave of given frequency, we show that the possible steady-state pulse velocities form a discrete set, qualitatively changing the previous picture of self-induced transparency. The selection mechanism cannot be seen in a perturbative expansion about the slowly varying envelope approximation.

Upper-atmosphere zonal winds from satellite orbit analysis: An update

The rotation rate Λ of the upper atmosphere can be evaluated from the observed changes in satellite orbital inclination, and in 1983 we reviewed the results then available. From the 85 values accepted for the review, it was possible to determine the variation with height (130–680 km), local time and season; but dependence on other parameters was not established. The present paper updates the previous review, incorporating 18 new values determined in the past 5 years and generally of better accuracy. The previous picture is strengthened by the new data but not significantly changed. After adding the new results, we find that the average value of Λ increases from 1.0 rev day −1 at 125 km height to about 1.2 at 300 km, and then decreases to about 0.9 at 500 km; Λ is higher in the evening (18–24 h), with a maximum value near 300 km which corresponds to a West-to-East wind of 150 m s −1, and is lower in the morning (06–12 h), with East-to-West winds of order 50 m s −1 at heights of 200–400 km. The values of Λ are higher in winter than in summer for heights of 200–300 km, and there is an indication that Λ may vary with solar activity, being about 0.1 lower for medium solar activity than for high or low solar activity. Results for heights above 450 km are still sparse.

Edge Fluctuations for the One Dimensional Supercritical Contact Process

We consider the one dimensional supercritical contact process with initial configurations having infinitely many particles to the left of the origin and only finitely many to its right. Starting from any such configuration, we first prove that in the limit as time goes to infinity the law of the process, as seen from the edge, converges to the invariant distribution constructed by Durrett [12]. We then prove a functional central limit theorem for the fluctuations of the edge around its average, showing that the corresponding diffusion coefficient is strictly positive. We finally characterize the space time of the system. In particular we prove that its distribution shifted in space by at (t denotes the time and a the drift of the edge) converges when t goes to infinity to a 2-2 mixture of the two extremal invariant measures for the contact process. 1. Introduction. In this article we study the one dimensional supercritical contact process, a stochastic process with infinitely many interacting particles which move on Z, the set of all the integers. We consider initial states with infinitely many particles to the left of the origin and finitely many to its right. We first prove that at large times the state of the system approaches some definite structure which, as time increases, rigidly shifts to the right: A steady state propagates from the left to the right with constant speed through the formerly empty region. The system is a (very schematic and rough) microscopic model for the formation and propagation of one dimensional shock waves, as we shall see in some more detail in the sequel. At large times we can distinguish three different space regions: The first two are semiinfinite intervals which extend to - oo and + oo, respectively, while the third one is the interval which connects the first two. In the first region the state looks like the nonzero density equilibrium state for the supercritical contact process, while, in the second it is the empty state. The third is the interesting region. It describes the front. We find that the state there is (close to) a superposition of the two extremal equilibrium states. The weight of the decomposition ranges from 1 (all the weight to the nonzero density state) to 0, as one moves from left to right. As the time t increases, the previous picture shifts to the right and, at the same time, the size of the front wave increases (like tl/2). The picture is very similar indeed to that found by Wick [25] in a zero range model. Our result is a consequence of a very detailed analysis of the motion of the first particle in the system, the edge, and of a precise knowledge of the of the state as seen from the edge. Such

Synthetic high coding for the pal luminance signal

For the transmission of PAL TV signals, the data rate of the luminance signal should not exceed 3-3.4 bit/pel, and the quality should fulfil the TV signal transmission standard. We suggested a synthetic high coding combined with DPCM coding for the luminance signal to meet the requirement. A 1-D FIR filter is used for filtering out the low signals. The sampling rate of low signal is lowered by subsampling and the signals are then coded in the usual DPCM manner. The difference of the luminance signal of present picture element with its previous picture element, when it exceeds a threshold, is the edge signal. The edges are then separated into two kinds, the relevant edges and non-relevant edges, according to the masking effect of visual perception. Those edges that can be discarded, which can not be perceived visually when the reconstructed picture is compared with the original picture, are non-relevant edges. The relevant signals and their addresses are coded and called the high signal. We have obtained a coding rate of 3.3 bit/pel for the luminance signal. The quality of the coded picture is similar to an 8 bit/pel PCM picture by subjective test. The errors in different steps of the coding are discussed. The limitation of the method is also discussed.

Dali's "Metamorphosis of Narcissus" Reconsidered

The article deals with Dali's Metamorphosis of Narcissus in a new light tracing its novelty by comparing it to both previous pictures and literary sources. Both Dali's picture and poem were influenced by alchemical sources. Various sources for the egg are found in Maierus' Atalanta Fugiens, 1618, as well as for other elements such as the hermaphrodite. The article also relates the themes to Dali's autobiography: both to his brother's death and his own cure through Gala. The opening of the head from which the flower sprouts is shown to be a continuation of therapy. A seventeenth century tradition of cure (Bosch's Cure of Folly) seems to have been in the background to Dali's version. It is both in the picture and in the poem that the alchemical and the autobiographical meet.

Heisenberg picture approach to polarization transfer by the DEPT sequence

The simple Heisenberg vector model, though useful for numerous nmr pulse sequences, was found inadequate to describe the DEPT sequence, which was subsequently analyzed by an unwieldy Schroedinger picture approach. Because this latter approach is not amenable to treating either deviations from, or applications of, the ideal DEPT sequence which arise in practical cases, a Heisenberg picture analysis is presented which is more mathematically formal than the simple vector model. In terms of efficiency, flexibility, and generality this represents a vast improvement on the previous Schroedinger picture approach which was restricted to treating CH, CH 2, and CH 3 groups individually for specific initial conditions. The new approach is applicable to a general IS n group, where the spin of I is one-half but that of S is arbitrary, for a variety of initial conditions. More importantly it is efficient enough to form the basis of analyses of the more complicated DEPT-type sequences which will be used for practical applications.

High-Speed Transmission of Sequential Freeze-Pictures by Extracting Changed Areas

A very high-speed freeze-picture transmission system via telephone lines is realized by sending only the changed areas from the previous picture. Transmission speed is improved in reverse proportion to the changed areas compared with conventional systems. Increase in circuit size is nominal. The new system is also much simpler than interframe codecs because it does not employ complicated coding mode controls, addressing, or buffering. Block size of the changed areas is selected to satisfy both fast transmission speed and circuit simplicity. High-speed transmission compatible with high picture quality is achieved by extraction of changed blocks using both the average value of the picture signal difference in each block and the maximum value. Protection of picture data against transmission errors is achieved using two synchronizing data groups among tripled addressing data groups. Reduction of impairments due to errors in DPCM picture data using backward decoding is also proposed and adopted.

Structure of the sunspot penumbra

An exceptionally highly resolved sunspot photograph is presented which reveals the fine-scale structure of the photospheric penumbra down to 0.2 arcsec. The photograph was taken through a glass filter in a 170-A FWHM band centered on 4660 A on the 65-cm vacuum Gregorian telescope at Big Bear Solar Observatory during practically perfect seeing. The photograph reveals the penumbra to be full of extremely fine-scale fibril structures, with apparent widths near the resolution limit. The three-dimensional structure of the photospheric penumbra is seen to be similar to that of the chromospheric penumbra and superpenumbra, with dark fibrils arching above a lower brighter structure and many of the bright fibrils representing portions of wider bright structures shining through the narrow spaces between the elevated dark fibrils. Thus, in contrast to previous pictures, much of the dark component of the photospheric penumbra is not physically analogous to the intergranular dark lanes in the normal photosphere.

Ab initio study of β-lactam antibiotics. II. Potential energy surface for the amidic CN bond breaking in the 3-cephem + OH − reaction and comparison with the β-lactam + OH − reaction

The potential energy surface for the β-lactam amidic CN bond breaking in the 3-cephem + OH − reaction was investigated by using the ab initio Hartree—Fock method with a 9s6p/7s3p/3s basis set. The investigated reaction is a model of the reaction between an antibiotic cephalosporin and an enzymatic nucleophilic group, this last reaction being related to the mode of action of β-lactam antibiotics. The minimum-energy reaction path is characterized by a tetrahedral intermediate ≈ 116 kcal mol −1 more stable than the reagents, by a barrier which corresponds to the partial breaking of the amidic bond and is ≈ 7 kcal mol −1 above the intermediate and by a product ≈ 31 kcal mol −1 more stable than the intermediate. The analysis of the wavefunction along the reaction path and the comparison with the β-lactam + OH − reaction pointed out the role of electron-withdrawing groups on the height of the barrier and the role of intramolecular hydrogen bonds on the structure and energy of the product. The calculations suggest a model of the antibiotic activity of cephalosporins which is compared with previous qualitative pictures.

Coding isotropic images

Rate-distortion functions for 2-dimensional homogeneous isotropic images are compared with the performance of five source encoders designed for such images. Both unweighted and frequency weighted mean-square error distortion measures are considered. The coders considered are a) differential pulse code modulation (DPCM) using six previous samples or picture elements (pels) in the prediction--herein called 6-pel DPCM, b) simple DPCM using single-sample prediction, c) 6-pel DPCM followed by entropy coding, d) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8 \times 8</tex> discrete cosine transform coding, and e) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4 \times 4</tex> Hadamard transform coding. Other transform coders were studied and found to have about the same performance as the two transform coders above. With the mean-square error distortion measure, 6-pel DPCM with entropy coding performed best. Next best was the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8 \times 8</tex> discrete cosine transform coder and the 6-pel DPCM--these two had approximately the same distortion. Next were the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4 \times 4</tex> Hadamard and simple DPCM, in that order. The relative performance of the coders changed slightly when the distortion measure was frequency weighted mean-square error. From <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R = 1</tex> to 3 bits/pel, which was the range studied here, the performances of all the coders were separated by only about 4 dB.

Deterioration of the Microcirculation in Diabetes

Studies of the microcirculation in diabetes in the last fifteen years have concentrated heavily on anatomic and biochemical abnormalities of the capillary basement membrane. Greater insights into basement membrane changes have eclipsed the previous picture of widespread progressive deterioration of the entire microcirculation. The history, variety of organ involvement, pattern of circulatory decline, and associated anatomic, physiologic, and biochemical findings are re-examined so that recently described potential mechanisms for the development of diabetic microangiopathy may be understood in a broader perspective. The possible contributions of seven categories of diabetic changes to damage of the microcirculation are outlined. The categories are: (1) altered basement membrane, (2) altered cellular function, (3) cell metabolic changes, (4) altered blood flow properties, (5) distrubed hemostasis, (6) altered oxygen transport, and (7) altered hormone production. The variety of clinical manifestations in long-standing diabetes related to microangiopathy appears to be due to a combination of a widely variable over-all rate of progression and a differing ability of body tissues and organs to accommodate to the sequential circulatory changes. The slow rate of deterioration in most diabetics suggests that several abnormalities must interact to produce the observed progression. A clear understanding of the interactions responsible for diabetic microangiopathy is becoming more important as new options in the management of diabetes become available.

Changes in picture recognition memory over time using an exclusion set paradigm

Previous picture recognition studies have been insensitive because of ceiling effects (e.g., Standing, 1973) and have not dealt adequately with the problem of partial recognition. A recognition measure was devised to determine the amount of detail in picture memory on a relative scale. Complex line drawings were successively altered to make stimulus sets consisting of a prototype for presentation and a set of 15 cumulative variations (distractors) which were shown serially to subjects during recognition testing and rated for the confidence with which they could be rejected. The size of the set of pictures subjects could exclude was scored. Testing was done immediately or after delay periods of 1, 2, 7, or 60 days. Exclusion set size decreased significantly over delay.

Structure of insect fibrillar flight muscle in the presence and absence of ATP

Low-angle X-ray diffraction pictures were taken of Lethocerus flight muscle in one or other of its two inactive states, relaxation and rigor. They showed more detail than previous pictures and the parameters of the actin and myosin helices could be deduced from the spacings of the observed layer lines. Subunits consisting of actin monomers and of myosin heads were arranged on helices so as to conform to these parameters, and the diffraction patterns from these models were calculated. When these model systems resembled the structures observed in the electron microscope, the calculated diffraction patterns had layer Unes similar in radial distribution and relative intensity to those observed, with certain exceptions. The fit was quite critical, in that variation of the size and orientation of the subunits affected it considerably. The results support the idea that in rigor (i.e. without ATP) all of the myosin heads attach to actin monomers in a regular angled configuration. In contrast, on relaxation (i.e. on addition of ATP but no Ca 2+) most or all of the myosin heads detach from the actin and are arranged with a specific symmetry around the myosin filament. It is not necessary, however, to assume that they change shape or move far from the actin filament in this process. Features of the X-ray diffraction pattern which remained unaccounted for by this model can be explained on the basis of an arrangement of actin helices on a further helix around a thick filament. Types of extended lattices containing actin helices in statistical axial or azimuthal positions are discussed.

THE RELIABILITY OF PATHOLOGISTS

The slides from 35 cases of lymph node biopsies with the initial diagnosis of Giant Follicular Lymphoma or Giant Follicular Hyperplasia were re‐examined according to selected histo‐pathological criteria. The same slides were also sent for diagnosis to eight different trained pathologists without any information on previous diagnosis or clinical picture. The 35 patients were clinically followed up and their fates registered. There were some (2 of 19 cases) false positive diagnoses, and some (2 of 16 cases) false negative diagnoses. Differences of opinion between the pathologists were registered.

Upper-atmosphere density, determined from the orbits of Cosmos rockets

Observational values of air density at heights of 150–200 km at times of low solar activity are still sparse. In this paper the orbits of thirty-two Cosmos rockets and two other satellites are examined, to obtain new values of air density from the orbital changes. An improved method is used for satellites very near the ends of their lives. The results strengthen the previous picture of the day-to-night variation in air density at heights of 200–300 km, and indicate a substantial day-to-night variation of density down to 170 km at times of low solar activity. The results at heights between 160 and 200 km suggest that recent theoretical models do not allow a large enough day-to-night variation in density. The analysis also shows, incidentally, that the mass/area ratios of the Cosmos rockets with inclinations of 65° differ appreciably from the values for those with inclinations of 49°.

The Surface Chemistry of Proteins. III. The Rigidity of Adsorbed Films at an Air-Water Interface

The results presented in Part II of this series on the adsorption of the proteins, β-globulin, pepsin, and insulin at a white oil, 5 per cent, oleyl alcohol-water interface have been extended to the petrol ether-water and air-water interfaces by studying the surface rigidity of the films formed. The previous picture of the process of adsorption has been generally confirmed but there are certain differences between the oil-water and air-water interfaces which are discussed.

The Motion Picture in Its Economic and Social Aspects. Annals of the American Academy of Political and Social Science.

Previous articleNext article FreeBook ReviewsThe Motion Picture in Its Economic and Social Aspects. Annals of the American Academy of Political and Social Science.S. P. B.S. P. B. Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Social Service Review Volume 1, Number 4Dec., 1927 Article DOIhttps://doi.org/10.1086/630329 Views: 1Total views on this site Copyright 1927 The University of ChicagoPDF download Crossref reports no articles citing this article.

TWO PICTURES BY MICHIGAN ARTISTS

Previous articleNext article FreeTWO PICTURES BY MICHIGAN ARTISTSPDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Volume 7, Number 6March 1926 Article DOIhttps://doi.org/10.1086/BULLDETINST41826522 Views: 2Total views on this site Journal History This article was published in the Bulletin of the Detroit Institute of Arts of the City of Detroit (1919-1948), which is continued by the Bulletin of the Detroit Institute of Arts (1948-present). PDF download Crossref reports no articles citing this article.

A SYNDROME OF THE VISUOPSYCHIC CORTICAL AREA—BASED ON STABILE HALLUCINATIONS AND DEFECTIVE VISUAL ASSOCIATION IN A SANE PERSON

The discussion of this subject presupposes that in normal persons the stimuli perceived by the visuosensory center are transmitted to the visuopsychic areas, are there compared with previous visual pictures and are recognized as similar or dissimilar. There they are stored, but the manner in which they are stored is unknown. Memory pictures stored in the visuopsychic center can be recalled to the field of consciousness either by the will or by stimuli coming from other cortical areas through the association tracts. Stimuli coming from without through the visual organs can also recall these memory pictures, and the flow of these stimuli is always from the visuosensory to the visuopsychic area. Never under normal conditions can the process be reversed. Stimuli from the visuopsychic or other cortical areas cannot stimulate the visuosensory areas. If this were not true, we could never be certain of the objective reality of our visual

Cloud Forms1

MOST writers on clouds put forward their own system of classification, much to the confusion of the subject; Mr. G. A. Clarke is therefore to be congratulated on adhering to the international classification in his recently pub lished book. He says that even to divide the recognised types into sub-types makes the classification unwieldy, and is open to the objection that, “particularly in the case of the cirrus . . . one sub-type may be transformed into another and then perhaps return to its origi1 nal form all within the space of a few minutes.” He even sug gests that any change should rather be in the direction of further simplification. In chap. ii. the international classification is given in full, so that for English readers Mr. Clarke's book may well supersede the Cloud Atlas, for the former contains all the essentials to be found in the text of the latter, and the illustrations cannot for a moment be com pared. Where the atlas gives a few illustrations, some very indif ferent, of each type, Mr. Clarke gives numerous examples that for variety, wealth of detail, and excellence of production easily surpass previous pictures.