Rhythmic Character Research Articles

Branchial innervation and ciliary control in the ascidian Corella.

The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded ‘ciliary arrest potentials’ probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relaxing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca2+, so that the ciliary control here may have some close parallels with that described forParamecium.

Patterns of spontaneous unit activity in the ventrolateral thalamic nucleus of cats

Patterns of spontaneous unitary activity were analysed in the ventro-lateral thalamic nucleus of unanaesthetized cats. Patterns of discharges were correlated with the electrocorticogram. A new logrithmic joint interval distribution has been introduced to study the serial order of intervals ranging over a large domain of time. During slow cortical waves, burst of high frequency discharges appeared, as well as under light chloralose anaesthesia, where they had a sustained rhythmic character. The intervals within the bursts lengthened. The mode of interspike interval distributions of the intervals composing the bursts ranged from 1.8 to 3.6 msec. During slow cortical waves there was no synchronization of the bursts from two cells recorded with the same microelectrode. During fast cortical waves the type of activity observed represents a random process with a slight dependence between successive intervals. The modes of the corresponding interspike interval distributions ranged from 4 to 22 msec. Under light chloralose anaesthesia no correlation was observed between interburst intervals and measurements describing bursts.

Syllable Structure and Sentence Rhythm—A Cross Language Study

Differences in segmental structure between English, French, and Polish were examined to determine the effect of this structure on perceived rhythm. In conversational French the sequence VC♯CV́ is uttered as V♯CCV́; these sequences are not homophonous in English or Polish. Assuming that the rhythmic character of the second syllable of such a sequence depends very little upon segments preceding the juncture, then VC♯CV́ and V♯CCV́ should appear rhythmically similar in French but different in both English and Polish, whereas V♯CV́ and VC♯CV́ should be similar in both English and Polish, but different in French. Nonsense utterances containing VC♯CV́, V♯CCV́, and V♯CV́ sequences were produced by native English, French, and Polish speakers; other native speakers judged the rhythms of these utterances by tapping their fingers in time to the stressed syllables. Preliminary data suggest that (1) listeners “hear” the rhythm of an utterance more clearly when it is spoken by a compatriot than by a foreigner, and (2) listeners tend to perceive rhythmic structure in terms of their own linguistic rules, regardless of the language of the utterance.

Computer Applications to Bartók's Serbo-Croatian Material

In the Introduction to his study of the Parry Collection of Yugoslav folk songs Béla Bartók contrasts ‘lexicographical’ and ‘grammatical’ principles in the systematic grouping of folk melodies. Although the former makes it possible to locate a melody by comparatively simple means, Bartók states, the latter is to be favoured; it is of higher importance “to get a clear idea of the relationship of melodies than to be able to locate them easily”. He then enumerates the components of his own grammatical system which, in order of weight, include: section structure, metric (syllabic) structure, rhythmical character, final notes of sections (caesurae), range, and so forth (cf. Plate 1 column headings).

Response Model Design for a Rhythmic Delta-Platform Domain, Devonian Catskill Complex of New York: ABSTRACT

Investigation of the physical stratigraphy of the Middle and Upper Devonian of southeastern New York has shown that this sequence of the Catskill Deltaic Complex might be separated naturally into a set of sedimentary domains. The North Point (lowermost Upper Devonian), one of these domains, is characterized by rhythmic patterns in sediment color, texture, and petrology; sedimentary structures; sediment transport directions; lithologic sequences; and lithosome geometries. The rhythmically recursive sequence of the North Point consists of (in ascending order): (A) polymictic conglomerate, (B) gray conglomeratic subgraywacke, (C) gray subgraywacke, (D) red subgraywacke, (E) red siltstone, (F) red mudrocks, (G) olive mudrocks, (H) gray mudrocks, and (I) sub-protoquartzite. Various physical and statistical models of source, distribution, accumulation, and modification realms of the process-response system of the North Point were simulated on an electronic computer. The algorithm for a model of the process-response system of a rhythmic sequence, obtained by integration of relative aspects of these models, may be approximated by six sub-sets of equations; each sub-set is an attempt to characterize the status of process elements in the development of a response phase. Translated into operational format these phases are: (1) early regressive phase (units A, B,); (2) middle regressive phase (B, C); (3) late regressive phase (D, E); (4) paralic stability phase (E, F); (5) early transgressive phase (G, H); and (6) late transgressive phase (H, I). The general aspect of this model is coarse-grained sediments (A, B, C) passing upward into finer sediments (E, F, G, H), forming a platform sequence which is rhythmically recursive. Homogenization at the strand zone and re-organization on the distal portion of the platform produces an inverted sequence (fines grading upward to coarser units). This model recognizes two components of subsidence, local and regional, as dominant process elements of the accumulation realm. The regional component is decomposed into he effects produced by compaction of the underlying sediment pile and those produced by subsidence of the Devonian sub-basin. The local component results from surface and near-surface compaction of sediment deposited during phases 3, 4, and 5 (units E, F, G, H) of a rhythmic sequence. The algebraic sum of the interaction of these two process elements may have profound effects on the character and mode of the response, producing transgression in one part of the domain, while regression or stability characterizes another part. Within the framework of this model the rhythmic character of the North Point is thought to be the response to the interaction of: (1) source contribution activity; (2) design of transport and dispersal systems; (3) influence of sub-basin and platform dynamics on the character and mode of the accumulation; (4) modification of the accumulation by processes such as compaction, erosion, diagenesis, and structural adjustments. End_of_Article - Last_Page 336------------

Mid-Carboniferous sedimentation in the Midland Valley of Scotland

Variations in thickness of mid-Carboniferous strata in the Midland Valley reflect variations in the original pattern of subsidence. This pattern is thought to be deep-seated in origin and probably related to the Variscan orogeny. Variations in sedimentation facies in space and time suggest the operation throughout Carboniferous times of an epeirogenic movement with at least two orogenic episodes. It is suggested that the Carboniferous strata were deposited in a delta-flank depression, the rhythmic character of the succession being due to alternating phases of abundance and scarcity of clastic detritus superimposed on a history of more or less continuous subsidence.

Deux trouvailles de ceratites dans le "calcaire coquillier" lorrain

Abstract Describes Progonoceratites saraviensis n.sp. from the basal zone of the Ceratites limestone of the Triassic limestone complex of Lorraine, France, and discusses its paleogeographic and paleoecologic significance. The cephalopod is considered to have been a member of an abundant population which inhabited a marine bottom and which perished catastrophically. The thanatocoenosis constitutes further proof of the rhythmic character of sedimentation of the Triassic limestones.

A boring in the millstone grit near darwen, lancashire

AbstractThe geological section exposed in a deep boring for water in the Millstone Grit near Darwen, Lancashire, is described. Details are given of the lithology and palaeontology throughout a thickness of 700 ft. of rock, extending from the Holcombe Brook Grit well into the Fletcher Bank Grit. In discussion, the rhythmic character of sedimentation is emphasised, and attention is also particularly drawn to the importance of marine bands (with Gastrioceras aff. sigma, Reticuloceras reticulatum early mut. γ and late mut. β) and a Lingula band in determining the Grits.

Rhythm and synchronism of tectonic movements

Comments on critical discussion by Gilluly and Rutten of Stille9s conclusions concerning orogenic epochs, and suggests that while the terms "world-wide" and "contemporaneous" should be used with caution, orogenic movements in widely separated regions of the earth can be correlated in time, imply a common deep-seated cause, and when plotted against geological time show both a rhythmic character and time relations with other phenomena such as ice ages, plutonism and volcanism, and transgressions and regressions of epicontinental seas.

Über die Kräfte bei der Bildung der Erdkruste

In reviewing the theories of the formation of the earth, we miss a unifying force that keeps the mechanism in movement. Isostasy, contraction, radioactivity alone are not sufficient, in as much as additional “cosmic” forces must be called to help. In developing further the theory of the sub-surface streamings, we have gone into the effect of the oceanic cold floors. A part of the cooling process that maintains equilibrium with the solar radiation is displaced through the sinking of the cold water to the bottom of the sea. The cooled and therefore heavier bottom presses upon the adjacent fluid zone and produces a sub-surface streaming of the solid lands which are thus raised up, especially at their edges. The denudation of the solid land carries the thrown-up masses back again into the sea, and thus arises a compression of the outer shell that furthers the process already begun and maintains it in a circulatory form. — The rhythmical character of the earth's history can be explained from the interruptions that this circulatory process has suffered through physical discontinuities.

EFFECT OF TEMPERATURE UPON SHELL MOVEMENTS OF CLAMS, VENUS MERCENARIA (L.)

1. A new apparatus, by means of which the shell activities of many bivalve mollusks can be measured and recorded, is described. 2. The analysis of 399 daily records of shell activities of 47 clams, subjected to temperatures ranging from — 1.0° to 28.0° C., showed that the length of time which the animals remain open partly depends upon the temperature of the surrounding water. 3. For the majority of clams hibernation begins soon after the water temperature decreases to 5.0° and 6.0° C. At lower temperatures the clams may remain completely closed for very long periods. No shell movements were exhibited, and no disposal of ejecta occurred. 4. Within the temperature range of 3.9° to 10.9° C., the average period of openness increased from 4 to 88 per cent of the total time, showing a correlation with the rise of temperature. 5. There was no correlation between the duration of openness of the clam shells and the temperature increase from 11.0° to 27.9° C. Within this temperature range the shells were open from 69 to 90 per cent of the total time, but the percentage did not increase simultaneously with the increase of water temperature. 6. The highest percentage of time open was recorded at temperatures 21.0° to 22.0° C., when the clams remained open 90 per cent of the total time, or 21 hours and 36 minutes per 24-hour period. 7. Small changes in the temperature of the surrounding water did not influence the shell movements of clams. 8. There appeared to be no definite periodicity in the clam shell movements. During brief intervals, the shell movements may be of a periodic type and exhibit a rhythmic character, but generally they appeared to be unsystematic and inconsistent. 9. There were considerable individual variations in the behavior of clams kept under identical environmental conditions. 10. Under the conditions of the experiments no definite correlation between the stages of tide and the shell movements of the animals could be detected. 11. The animals were closed for somewhat longer periods in daytime than in darkness.

Rhythms in the rate of reproduction of Am ba bigemma

A specimen of Amœba bigemma (Schæffer) was isolated December 7, 1921, and eight lines of its descendants have been bred in pedigree cultures to the 100th generation (May 15, 1922). The cultures have been carried on standard beef extract and kept at a temperature varying from 20° to 24° C. Vegetative division has been uninterrupted by spore or gamete formation. The data obtained by the daily isolation method show that the rate of division of the organism under the conditions of the experiment fluctuates considerably. At intervals during the pedigree there were daily divisions, or frequently one division every other day for a short time. Occasionally two fissions occurred in one day, while in a single instance an Amœba divided three times during twenty-four hours. Periods of inactivity when no fissions took place were common, and varied in length from one to twelve days; but whereas the absence of division for one or two days was of frequent occurrence, that of over three days was rare. An average of the daily divisions in eight lines for a period of ninety days showed the rate to be slightly above one division in two days. In contrast to this daily irregularity there was a general periodicity in the fission rate which was revealed only by an examination of the data covering longer intervals of time. By averaging the number of divisions in a single line for five-day periods, a rhythmic character of the fission rate was apparent in the form of alternating periods of high and low reproductive activity; one low point to the next comprising about twenty days. Whether these rhythms are of the same nature as those in the Infusoria can be determined only after more study of this and other Amœbœ in pedigree cultures.

ENCEPHALITIS WITH INVOLUNTARY MOVEMENTS

The four cases herein reported show such a characteristic picture that they may be classed as belonging to a somewhat individual type of encephalitis. In fact, after two of them had been described,1an article2came to the writer's attention containing a clinical picture differing in minor particulars only from that of the cases I report. Few cases of encephalitis with involuntary movements have been described. In those reported by Buzzard,3the movements seem to have differed in several interesting ways from those of my patients. He states that all these movements cease during sleep, whereas in the three cases that I observed they were much more active during sleep. Buzzard lays no emphasis on the rhythmic character of the movements—one of the most striking features in my cases. Only in Cases 10 and 12 does he speak of movements of the shoulder girdle muscles;

On the Rhythm of Egg Production

The subject matter of this paper presents some points of an investigation still in progress. The term rhythm of egg production is used rather than rate, in order to emphasize the rhythmical character of egg extrusion. Although true that the observed rhythm is by no means regular, still each hen often tends to produce eggs according to a fairly characteristic rhythm. Superimposed on the daily rhythm, are evidences of other rythms having a beat measured by months or years. Of course, from another standpoint egg production is a more or less continuous process. The Rhythm as Shown by the Time of Day the Egg is Laid:—The time of day at which the eggs have been collected from the trap nests has been recorded at half-hour intervals, and as they are collected at least every hour and a half, the time collected represents approximately the time when the egg was . . .

Proper Names in Old English Verse

It is true that the poets often allow proper names to disturb the rhythmic character of verse; but there are limits beyond which few versifiers will be found to push any special license that they may be disposed to exercise in the use of names. The famous Shakespearean crux in the line,“Lucius, Lucullus, and Sempronius Vllorxa,”[Timon, III, iv, 112.]

The rhythmical character of the process of segmentation

<i>The rhythmical character of the process of segmentation</i>

The rhythmical character of the process of segmentation

The rhythmical character of the process of segmentation

On the mechanism stromboli

Stromboli and Masaya stand alone, so far as observation has yet gone, amongst the volcanic vents of our planet, in the remarkable characteristic of having a distinctly rhythmical intermittence and recurrence in their eruptive action. Masaya, though known for about 300 years, has been but little observed, so that some doubt may exist as to whether its action be truly intermittent and recurrent or not; and if we leave it aside for future observation, Stromboli stands unique amongst terrestrial volcanoes in the rhythmical character of its eruptions, more or less accurate observations as to which are upon record for above 2000 years. Every volcanic vent is indeed intermittent, and often recurrent, in its action, which has been properly denominated paroxysmal, but no law can be traced in the intervals of time elapsing between the paroxysms. A vent may suddenly open and a cone be thrown up, as in the case of Monte Nuovo, and after this burst volcanic effort may cease there, perhaps permanently; or, as in the case of Vesuvius, prior to a. d. 79, a period of repose may exist in a volcanic cone already formed, exceeding human local tradition, to be succeeded by paroxysmal efforts, varying enormously in intensity, and with intervals in time between successive eruptions varying from hours to centuries. In all these there is no rhythmical recurrence, or at least none that, upon the narrow scale open to our observation, can be viewed as such. In Stromboli, on the contrary, there is a distinctly rhythmical intermittence and recurrence, so regular in time, and preserving for centuries such a general uniformity in energy, and of such slight violence, as to point to some distinct train of mechanism as producing it—that mechanism, whatever be its nature, being comprehended within a moderate distance from the surface, and not referable to the more mighty and deepseated forces which determine the uncertain and altogether unpredictable paroxysms of volcanoes generally. Not that the rhythmic intervals of Stromboli are precisely the same at all times, as has been erroneously stated by many travellers, nor the violence of its outbursts at all times alike; but both vary within narrow limits during the immense historic period that it has been observed. No satisfactory explanation has yet been given, so far as the author is aware, of the physical and mechanical condition constituting the mechanism upon which this extremely curious rhythmical action depends; and it is the object of this paper to point out what appears to be its real nature. It is the more worthy of attentive study, as Stromboli is in reality the link that connects two widely different phenomena—namely, the ordinary cone of eruption and the geyser. Stromboli is, in fact, a volcano and a geyser united and acting together in the same vent, the rhythmical action which characterizes the geyser being thus communicated, within certain limits, to the otherwise irregular and accidental activity of the volcano. Passing ancient accounts, Stromboli has been visited in modern days, amongst men of science, by Spallanzani, Dollomieu, Hoffman, Scrope, Daubeny, and several others; but no very full or exact description of the crater and its adjuncts, much less any adequate explanation of the curious mechanism of its action, has been given by any of these writers.