Circular islands as resonators of long-wave energy

1972 ◽  
Vol 272 (1225) ◽  
pp. 361-402 ◽  
Keyword(s):  
Continental Shelf ◽  
Power Spectra ◽  
The Other ◽  
Wave Radiation ◽  
Other Hand ◽  
Water Region ◽  
Trapped Wave ◽  
Critical Circle ◽  
Island Shelf ◽  
Wave Modes

A study is made of the long gravity waves trapped around isolated, cylindrically symmetrical island-continental shelf topographies. Numerical evaluation of the discrete complex spectra of the trapped wave modes reveals that the oscillations are of two, essentially different kinds. The ‘ trapped-leaky ’ wave-modes are the analogue of the trapped (edge) wave-modes along straight shorelines and many of their properties, including the Coriolis split in frequency, are deducible from the simpler geometry. On the other hand, the ‘shelf-island’ modes have no counterpart in the motions trapped along extended shorelines; they are virtually generated in the ocean round a vertical-walled circular island of radius equal to that of the island-shelf system at the sea floor. It is shown that the trapped wave-modes do not necessarily have the ‘inner critical circle’ property elucidated by Longuet-Higgins (1967) for the similar modes of oscillations of the waters over a circular seamount. On the other hand, the modes do have ‘wave’ domains adjacent to the coast whenever the undisturbed depth of water at the island’s shoreline is zero; there may still be critical circles in the shallow water region over the continental shelf. For those islands where the water has non-zero depth at the shoreline, the computation verifies Longuet-Higgins’s hypothesis (Longuet-Higgins 1967, § 13) concerning the affect on the trapped wave-modes of the presence of an island in the middle of the sea-mount. It is also shown that the fundamental ‘ trapped-leaky’ modes dominate the disturbance observed at the coast when plane wave radiation from the ocean interacts with the island-shelf system. For the particular example where the excitation has the form of a rectilinear pulse, it is shown that power spectra of the resulting oscillations exhibit some of the features of the spectra of real wave records made at islands following the passage of tsunamis.

scholarly journals The occurrence of non-pulsating stars in the γ Dor and δ Sct instability regions

2013 ◽  
Vol 9 (S301) ◽  
pp. 63-66 ◽  
Author(s):  
Joyce A. Guzik ◽  
Paul A. Bradley ◽  
Jason Jackiewicz ◽  
Katrien Uytterhoeven ◽  
Karen Kinemuchi
Keyword(s):  
Effective Temperature ◽  
Power Spectra ◽  
Light Curves ◽  
The Other ◽  
Pulsating Stars ◽  
Driving Mechanisms ◽  
Other Hand ◽  
Instability Regions ◽  
Physical Reasons ◽  
Ppm Level

AbstractWe examine the light curves of over 2700 stars observed in long cadence by the Kepler spacecraft as part of the Guest Observer program. Most of these stars are faint (Kepler magnitude > 14), and fall near or within the effective temperature and log g range of the γ Dor and δ Sct instability strips. We find that the pulsating stars are obvious from inspection of the light curves and power spectra, even for these faint stars. However, we find that a large number of stars are ‘constant’, i.e. show no frequencies in the 0.2 to 24 d−1 range above the 20 ppm level. We discuss the statistics for the constant stars, and some possible physical reasons for lack of pulsations. On the other hand, γ Dor and δ Sct candidates have been found in the Kepler data spread throughout and even outside of the instability regions of both types that were established from pre-Kepler ground-based observations. We revisit mechanisms to produce g- or p-mode pulsations in conditions when these modes are not expected to be unstable via the He-ionization κ effect (δ Sct) or convective blocking (γ Dor) pulsation driving mechanisms.

scholarly journals The merger of geophysical vortices at finite Rossby and Froude number

2018 ◽  
Vol 848 ◽  
pp. 388-410 ◽  
Author(s):  
Jean N. Reinaud ◽  
David G. Dritschel
Keyword(s):  
Froude Number ◽  
Gravity Wave ◽  
Potential Vorticity ◽  
Initial Conditions ◽  
The Other ◽  
Vertical Shear ◽  
Wave Radiation ◽  
Rossby Number ◽  
Other Hand ◽  
Vorticity Anomaly

We investigate the merger of two co-rotating geophysical vortices at finite Rossby and Froude number. The initial conditions consist of two uniform potential vorticity vortices in near-equilibrium and in a nearly ‘balanced’ state (i.e. with negligible emission of inertia–gravity wave radiation). We determine the critical merger distance between the two vortices. This distance is found to increase with the magnitude of the Rossby number: intense cyclones or intense anticyclones are able to merge from further apart compared to weaker cyclones and anticyclones. Note that the Froude number is proportional to the Rossby number for the near-equilibrium initial conditions considered. The critical merging distance also depends on the sign of the potential vorticity anomaly, which is positive for ‘cyclones’ and negative for ‘anticyclones’. We show that ageostrophic motions occurring at finite Rossby number tend to draw cyclones together but draw anticyclones apart. On the other hand, we show that anticyclones tend to deform more, in particular when subject to vertical shear (as when the vortices are vertically offset). These two effects compete. Overall, nearly aligned cyclones tend to merge from further apart than their anticyclonic counterparts, while vertically offset anticyclones merge from further apart than cyclones.

Sedentary Fisheries and Article 2(4) of the Convention on the Continental Shelf —A Plea for a Separate Regime

1969 ◽  
Vol 63 (1) ◽  
pp. 86-97 ◽  
Author(s):  
L. F. E. Goldie
Keyword(s):  
Natural Resources ◽  
Continental Shelf ◽  
International Law ◽  
The Other ◽  
Other Hand ◽  
Definition Of ◽  
International Law Commission ◽  
General Community ◽  
Law Commission

The open-endedness of the Continental Shelf Convention renders it vulnerable to misuse as a camouflage for extravagant claims by states seeking to extend their coastal jurisdiction far out into the abyss until, perhaps, they meet in an oceanic thalweg. The definition of the continental shelf in terms of exploitability and the inclusion of “sedentary species” among the “natural resources” of the continental shelf are the two greatest sources of this indeterminacy. Their elimination from the Convention would greatly reduce its fictional elements—the false colors it now provides for grandiose ambitions. On the other hand, the comment which follows does not purport to investigate the basic choice between accepting the exclusive competence of coastal states over sedentary fisheries and general community freedom from such competence. Assuming those issues to be beyond its scope, it is limited to the pragmatic evaluation of including sedentary fisheries within the scope of the continental shelf regime or, alternatively, of restoring a modified version of the Sedentary Fisheries Article which the International Law Commission proposed in 1951.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

ON THE OTHER HAND

1961 ◽  
Vol 6 (6) ◽  
pp. 222-223
Author(s):  
Edwin G. Boring
Keyword(s):  
The Other ◽  
Other Hand
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