scholarly journals Supersonic dispersion in gases

1934 ◽  
Vol 146 (856) ◽  
pp. 56-71 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Experimental Work ◽  
High Frequency ◽  
Response Curve ◽  
Wave Length ◽  
Soap Film ◽  
The Other ◽  
Rapid Degradation ◽  
Compressional Waves ◽  
Point Electrode

The rapid degradation of intensity suffered by compressional waves of high frequency in gases was first observed by pierce in carbon dioxide for frequencies in the neighbourhood of 2.10 5 cycles/sec. Although in the last few years a considerable number of measurements of the velocity of supersonic waves have been made, less experimental work has been done on the absorption . This present paper describes some work aimed at elucidating the mechanism of the phenomenon. Consideration was first given to the establishment of a source of vibrations of the requisite frequency. The possible apparatus reduces itself to four types: (1) edge-tones, (2) electric sparks, (3) small resonators of gas, (4) solid resonators; both of the latter types to be maintained by oscillating circuits incorporating valves. The frequency of an edge-tone depends directly on the velocity of the blast, and inversely on the distance from the blower to the edge, so that it should be possible to produce supersonic waves by making the former very large and the latter very small; in fact, Hartmann has already used such a source. The difficulty of maintaining constant blast velocity and the complications which the blast introduces in the propagation of such waves would, however, have made such a source unmanageable in the present work. Nekle-pajev has used sparks as sources in the examination of the absorption in air. But here again the frequency is difficult to measure or to maintain constant. Some success was obtained by the author with gaseous resonators consisting of short brass tubes terminated at one end by a brass stopper, and at the other end by a soap film, the distance between the two being half the wave-length at the frequency of excitation. The resonator was maintained in vibration by a valve oscillator, of which the plate was connected to a point electrode just above the soap film, while the grid was connected to the brass tube itself. Response of the resonator due to electrostatic attraction of the film was observed by the image of a glowing filament reflected from the slightly concave film on to a scale. By varying the tuning of the oscillator the response curve of the little resonator could be obtained.

Treatment of Upper Lip Wrinkles: A Comparison of the Sharplan SilkTouch Carbon Dioxide Laser with Ellman Radiosurgery

2000 ◽  
Vol 17 (1) ◽  
pp. 9-14
Author(s):  
Kimberly A. Rau ◽  
Jane Chew ◽  
Iris Gin ◽  
David Bradley Amos ◽  
James B. Bridenstine
Keyword(s):  
Carbon Dioxide ◽  
High Frequency ◽  
Carbon Dioxide Laser ◽  
Thermal Injury ◽  
Continuous Wave ◽  
High Energy ◽  
The Other ◽  
Side Effect Profile ◽  
Upper Lip ◽  
Average Laser

Introduction: High energy pulsed, or computer-scanned, continuous-wave carbon dioxide (CO2) laser has become a popular tool for wrinkle treatment because it causes minimal thermal injury and the tissue vaporization depth can be precisely controlled. Radiosurgery for this purpose has been used to a lesser extent, but is also beneficial for the treatment of facial wrinkles. The objective of this study was to compare the effectiveness and side effect profile of the Sharplan SilkTouch CO2 laser with those of the Ellman Surgitron FFPF radiosurgery unit in the treatment of upper lip wrinkles and is, to our knowledge, the first study to compare a CO2 laser with high-frequency radiosurgery for this purpose. Methods: Twenty female subjects with moderate to severe upper lip wrinkles were randomly treated with the SilkTouch CO2 laser on one side of the upper lip and radiosurgery on the other side. Results: The average laser-treated wrinkle score (0 = none to 5 = severe) decreased from 4.05 ± 0.2 before treatment to 1.6 ± 0.23 after treatment. The average radiosurgery-treated wrinkle score decreased from 4.2 ± 0.18 to 2.6 ±0.2 after treatment. The degree to which wrinkle score improved after laser treatment compared with radiosurgery treatment was statistically significant (P < .0051). Conclusion: Treatment with CO2 laser resulted in greater improvement of upper lip wrinkles than did treatment with radiosurgery.

scholarly journals Chance or Necessity—The Fungi Co−Occurring with Formica polyctena Ants

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 204
Author(s):  
Igor Siedlecki ◽  
Michał Gorczak ◽  
Alicja Okrasińska ◽  
Marta Wrzosek
Keyword(s):  
Molecular Identification ◽  
High Frequency ◽  
Its Rdna ◽  
The Other ◽  
Formica Polyctena ◽  
Ant Nests ◽  
Mutualistic Fungi ◽  
The Tropics ◽  
High Diversity ◽  
Better Than

Studies on carton nesting ants and domatia−dwelling ants have shown that ant–fungi interactions may be much more common and widespread than previously thought. Until now, studies focused predominantly on parasitic and mutualistic fungi–ant interactions occurring mostly in the tropics, neglecting less−obvious interactions involving the fungi common in ants’ surroundings in temperate climates. In our study, we characterized the mycobiota of the surroundings of Formica polyctena ants by identifying nearly 600 fungal colonies that were isolated externally from the bodies of F. polyctena workers. The ants were collected from mounds found in northern and central Poland. Isolated fungi were assigned to 20 genera via molecular identification (ITS rDNA barcoding). Among these, Penicillium strains were the most frequent, belonging to eight different taxonomic sections. Other common and widespread members of Eurotiales, such as Aspergillus spp., were isolated very rarely. In our study, we managed to characterize the genera of fungi commonly present on F. polyctena workers. Our results suggest that Penicillium, Trichoderma, Mucor, Schwanniomyces and Entomortierella are commonly present in F. polyctena surroundings. Additionally, the high diversity and high frequency of Penicillium colonies isolated from ants in this study suggest that representatives of this genus may be adapted to survive in ant nests environment better than the other fungal groups, or that they are preferentially sustained by the insects in nests.

Normal Synaptonemal Complex and Abnormal Recombination Nodules in Two Alleles of the Drosophila Meiotic Mutant mei-W68

Genetics ◽  
2003 ◽  
Vol 163 (4) ◽  
pp. 1337-1356 ◽  
Author(s):  
Adelaide T C Carpenter
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
High Frequency ◽  
Serial Section ◽  
The Other ◽  
Wild Type ◽  
Recombination Nodules ◽  
Section Electron ◽  
Serial Section Electron Microscopy ◽  
Section Electron Microscopy

Abstract The meiotic phenotypes of two mutant alleles of the mei-W68 gene, 1 and L1, were studied by genetics and by serial-section electron microscopy. Despite no or reduced exchange, both mutant alleles have normal synaptonemal complex. However, neither has any early recombination nodules; instead, both exhibit high numbers of very long (up to 2 μm) structures here named “noodles.” These are hypothesized to be formed by the unchecked extension of identical but much shorter structures ephemerally seen in wild type, which may be precursors of early recombination nodules. Although the mei-W68L1 allele is identical to the mei-W681 allele in both the absence of early recombination nodules and a high frequency of noodles (i.e., it is amorphic for the noodle phene), it is hypomorphic in its effects on exchange and late recombination nodules. The differential effects of this allele on early and late recombination nodules are consistent with the hypothesis that Drosophila females have two separate recombination pathways—one for simple gene conversion, the other for exchange.

scholarly journals Interferential comparison of the red and other radiations emitted by a new cadmium lamp and the michelson lamp

1933 ◽  
Vol 139 (837) ◽  
pp. 202-218 ◽  
Keyword(s):  
Fine Structure ◽  
High Temperature ◽  
Wave Length ◽  
The Other ◽  
Reference Standard ◽  
Definite Evidence ◽  
Electro Magnetic ◽  
The Many ◽  
Red Radiation ◽  
Red Line

It is now generally recognised that future definitions of the units of length will probably be based on the length of a wave of visible light. At present the wave-length of the red radiation of cadmium serves as the basis of all measurements of the lengths of electro-magnetic waves which are perceptible by optical means, and provisional sanction has been given to measurements of length on the same basis, as an alternative to direct reference to the metre. Whether the cadmium red radiation provides the best reference standard for all measurements of length has not yet been definitely established. Two international committees, one representing spectroscopists and the other metrologists, have sanctioned standard specifications for cadmium lamps of the Michelson type from which the red radiation may be produced. The two specifications differ from one another in certain details, but both are subject to the same objections. These objections are directed partly against the high temperature at which it is necessary to run the lamp and partly against the high voltage required to excite the radiation. Therefore, such hyperfine structure and asymmetry as may be present in the red line of cadmium is likely to be masked in the Michelson lamp by a combination of two phenomena —the enhanced Doppler effect due to the high temperature of the radiating cadmium atoms, and the effect of the moderately high intensity of the electric field. Were this not so, it might be somewhat surprising that no definite evidence of fine structure or asymmetry had so far been observed in the red line from the Michelson lamp, notwithstanding the many careful examinations, with the aid of the most sensitive interferometers, to which this line has been subjected, in view of its importance as the reference standard for all other wave-lengths. Recently Nagaoka and Sugiura have recorded that they have observed slight evidences of structure in the red radiation when excited under special conditions in which great precautions were taken to ensure extreme sharpness of the line. It is believed, however, that no subsequent confirmation of this effect has yet been published.

LONG DURATION ECHOES FROM AURORA, METEORS, AND IONOSPHERIC BACK-SCATTER

1953 ◽  
Vol 31 (2) ◽  
pp. 171-181 ◽  
Author(s):  
D. W. R. McKinley ◽  
Peter M. Millman
Keyword(s):  
Long Range ◽  
High Frequency ◽  
The Other ◽  
Very High Frequency ◽  
Long Duration ◽  
E Region ◽  
Very High ◽  
Visual Observations

In the course of the Ottawa meteor program some unusual echoes have been detected on 33 Mc. Echoes from the aurora are discussed and correlated with visual observations. Two mechanisms of radio reflections from the aurora have been proposed but the data here presented are insufficient to favor one over the other. On Aug. 4, 1948, six extremely long duration meteor echoes were observed which may have been due to abnormal ionospheric conditions. From time to time since August, 1948, a weak semipermanent echo has been recorded, usually appearing at a range of about 80 km., and enduring up to an hour. It is suggested that this echo is due to back-scatter from the same sources in the lower E-region that are presumed to be responsible for long-range very high frequency propagation.

XXVII.—The Inheritance of Long and Short Wings in the Weevil, Sitona hispidula, with a Discussion of Wing Reduction among Beetles

1928 ◽  
Vol 55 (3) ◽  
pp. 665-735 ◽  
Author(s):  
Dorothy J. Jackson
Keyword(s):  
Experimental Work ◽  
Adult Stage ◽  
Point Of View ◽  
The Other ◽  
Wing Dimorphism ◽  
Wing Reduction ◽  
Hereditary Factors ◽  
The Subject ◽  
The One ◽  
Evolutionary Point

It is well known that in many orders of typically winged insects species occur which in the adult stage are apterous or have the wings so reduced in size that flight is impossible. Sometimes the reduction of wings affects one sex only, as in the case of the females of certain moths, but in the majority of cases it is exhibited by both sexes. In many instances wing dimorphism occurs irrespective of sex, one form of the species having fully developed wings and the other greatly reduced wings. In some species the wings are polymorphic. The problem of the origin of reduced wings and of other functionless organs is one of great interest from the evolutionary point of view. Various theories have been advanced in explanation, but in the majority of cases the various aspects of the subject are too little known to warrant discussion. More experimental work is required to show how far environmental conditions on the one hand, and hereditary factors on the other, are responsible for this phenomenon. Those species which exhibit alary dimorphism afford material for the study of the inheritance of the two types of wings, but only in a few cases has this method of research been utilized.

scholarly journals Transduction mechanisms of bacteriophage ε15I. General properties of the system

1971 ◽  
Vol 18 (1) ◽  
pp. 9-19 ◽  
Author(s):  
R. W. Hedges
Keyword(s):  
High Frequency ◽  
Genetic Material ◽  
Recipient Strain ◽  
The Other ◽  
Donor Strain ◽  
General Properties ◽  
Show Evidence ◽  
Transduction Mechanisms ◽  
Defective Prophage

SUMMARYBacteriophageεγis capable of transduction both by replacement of a genetic segment of the recipient by the homologous genetic material from the donor strain and by the formation of defective transducing particles capable of lysogenizing the recipient strain ofS. anatum.The isolation of strains carrying such prophages, which have incorporated the lactose or arabinose operons, is reported. Lysogenic strains, carrying both normal and defective transducing prophage, form high-frequency transducing lysates. Other strains, carrying only defective prophage, show evidence that the association of prophage genes and transduced materials is stable since the loss of one frequently entails loss of the other.

Relative clauses in Agul from a corpus-based perspective

2020 ◽  
Vol 73 (1) ◽  
pp. 113-158
Author(s):  
Timur Maisak
Keyword(s):  
High Frequency ◽  
Relative Clauses ◽  
High Ratio ◽  
The Other ◽  
The Core ◽  
Text Corpora ◽  
The Asymmetry ◽  
Intransitive Verbs ◽  
Syntactic Restrictions ◽  
Locative Case

AbstractThis paper gives an account of participial clauses in Agul (Lezgic, Nakh-Daghestanian), based on a sample of 858 headed noun-modifying clauses taken from two text corpora, one spoken and one written. Noun-modifying clauses in Agul do not show syntactic restrictions on what can be relativized, and hence they instantiate the type known as GNMCCs, or general noun-modifying clause constructions. As the text counts show, intransitive verbs are more frequent than transitives and experiencer verbs in participial clauses, and among intransitive verbs, locative statives with the roots ‘be’ and ‘stay, remain’ account for half of all the uses. The asymmetry between the different relativization targets is also significant. Among the core arguments, the intransitive subject (S) is the most frequent target, patient (P) occupies second place, and agent (A) is comparatively rare. The preference of S and, in general, of S and P over A also holds true for most other Nakh-Daghestanian languages for which comparable counts are available. At the same time, Agul stands apart from the other languages by its high ratio of non-core relativization which accounts for 42% of all participial clauses. Addressee, arguments and adjuncts encoded with a locative case, as well as more general place and time relativizations show especially high frequency, outnumbering such arguments as experiencers, recipients, and predicative and adnominal possessors. Possible reasons for the high ratio of non-argument relativization are discussed in the paper.

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