Hemispherical Depressions Research Articles

The Global Topography of Mars and Implications for Surface Evolution

Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad rises. Material excavated from Hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary. The present topography has three major drainage centers, with the northern lowlands being the largest. The two polar cap volumes yield an upper limit of the present surface water inventory of 3.2 to 4.7 million cubic kilometers.

Stalagmite luminescence and peat humification records of palaeomoisture for the last 2500 years

Recent research has suggested that both raised and blanket bogs can provide proxy climate signals from variations in peat humification. In particular, oceanic margin sites have provided sensitive records that demonstrate century scale variations in humification. However, previous research has not compared records of peat humification with other terrestrial palaeoclimate proxies. Here, two records of climate change from an oceanic marginal site in NW Scotland are analysed. One, from a blanket bog, is derived from peat humification and covers the period 2100–100 BP. A second, from two stalagmites in a cave overlain by the bog, is derived from stalagmite luminescence wavelength variations for the samples deposited over 2500–0 BP. Both peat humification and stalagmite luminescence records demonstrate 90–100 year oscillations in bog wetness, that are attributed to variations in rainfall intensity or totals over this time period. It is argued that this is probably generated by a southward shift of the path of northern hemisphere depression tracks, possibly linked to variations in solar output.

Observations of the north polar region of Mars from the Mars orbiter laser altimeter.

Elevations from the Mars Orbiter Laser Altimeter (MOLA) have been used to construct a precise topographic map of the martian north polar region. The northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5-kilometer-deep hemispheric depression that is contiguous with the area into which most outflow channels emptied. Polar cap topography displays evidence of modification by ablation, flow, and wind and is consistent with a primarily H2O composition. Correlation of topography with images suggests that the cap was more spatially extensive in the past. The cap volume of 1.2 x 10(6) to 1.7 x 10(6) cubic kilometers is about half that of the Greenland ice cap. Clouds observed over the polar cap are likely composed of CO2 that condensed out of the atmosphere during northern hemisphere winter. Many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography.

Ovipositional Synergists and Artificial Diets for Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae)

We studied ovipositional synergists and artificial diets for rearing Trichogramma australicum. Artificial “diet A” included 40% haemolymph of Helicoverpa armigera (Hübner) final instar larvae, 30% of a 10% malt solution in deionised water, 20% chicken egg yolk and 10% Neisenheimer's salt solution with 76 units Penicillin and 76 units Streptomycin/ml diet. Artificial “diet B” was identical except Grace's insect medium® replaced Neisenheimer's salt solution. the number of T. australicum larvae in artificial eggs filled with diet A and diet B was not significantly different (P > 0.05). Significantly fewer (P < 0.05) larvae developed to pupae and adults in artificial eggs filled with diet A. Quantity and quality of artificial diet affected the mortality of T. australicum larvae reared in vitro. Ovipositional synergists included 10% gelatine solution, 10% polyvinyl alcohol solution or 1% agar solution in deionised water. Synergist test‐solutions were individually smeared on the external surface of artificial eggs (hemispherical depressions in plastic membrane). Eggs laid and number of T. australicum larvae produced were significantly higher in artificial eggs smeared with gelatine than artificial eggs smeared with polyvinyl alcohol, agar or non‐smeared (control) eggs.

Right hemisphere white matter non-verbal deficits and depression in adolescents and young adults in a psychiatric population

Right hemisphere white matter non-verbal deficits and depression in adolescents and young adults in a psychiatric population

Evaporation characteristics in laser welding ‐ fundamental study on theoretical modelling of laser welding (Report 2)

Summary Evaporation characteristics in CO2 laser welding stainless steel were experimentally analysed at power densities in a range from 5 × 104 to 107 W/cm2 with M2 of 1.4 and 5.6. Welding mode changes from a thermal conduction type to a deep penetration type at a critical power density around 4–5 × 105 W/cm2. Penetration depth tends to increase with decreasing M2 with accompanying decreased evaporation loss when the power density at the work surface is the same. The latent heat of evaporation is negligibly small, at most, around 1 % of laser power. In thermal conduction welding, where the power density is less than 4–5 × 105 W/cm2, the evaporation rate per unit area was found to be equivalent to that of deep penetration welding, indicating that the recoil force of the evaporation is at least as high as that of keyhole welding, producing a shallow hemispherical depression by the recoil force in the molten pool. The evaporation rate in deep penetration welding decreases with increasing aspect ratio of the...

Possible pathology in the snout and lower jaw of the Chinese Devonian lungfish,Sorbitorhynchus deleaskitus(Osteichthyes: Dipnoi)

ABSTRACT The holotype and only known specimen of Sorbitorhynchus deleaskitus, a large Devonian lungfish from Guangxi, China, is abnormal in the structure of the snout and lower jaw. The tooth plates show marked asymmetry and do not occlude when the jaws are placed in normal articulation. There is a large hemispherical depression with sinus tracts in the bone between the lower tooth plates. Both snout and lower jaw are abnormal in shape and only traces remain of ossified sensory tubules within the bone of the snout and mandible. The lower jaw of S. deleaskitus may have included a dentigerous cyst that developed from a persistent juvenile symphyseal tooth and grew large enough to distort the symphysis and cause malocclusion between the tooth plates. The cyst may have become infected, forming an abscess with sinus tracts in the bone below, and hyperplastic or neoplastic cells from the cyst may have spread to destroy normal sensory structures in the snout and lower jaw. If this interpretation is correct, the ...

レーザ溶接における蒸発特性 レーザ溶接の知能化に関する基礎研究（第２報）

Evaporation characteristics in CO2 laser welding stainless steel was experimentally analyzed at power densities in a range from 5×104 to 107 W/cm2 with M2 of 1.4 and 5.6. Welding mode transits from a thermal conduction to a deep penetration type at a critical power density around 4-5×105 W/cm2. The penetration depth tends to increase with decreasing M2 with accompanying decreased evaporation loss when the power density at the work surface is the same. The latent heat of evaporation is negligible small, at most around 1% of laser power. In the thermal conduction welding, where the power density is less than 4-5×105 W/cm2, the evaporation rate per unit area was found to be equivalent to that of the deep penetration welding, indicating that the recoil force of the evaporation is at least as high as that of the keyhole welding, providing a shallow hemispherical depression by the recoil force in the molten pool. The evaporation rate in the deep penetration welding decreases with increasing aspect ratio of the weld bead due to the condensation of the vapor at the side wall of the keyhole.

Hemisphere Preference, Phobia, and Depression

The present study was undertaken in order to examine whether depression and anxiety are related to preference for a right hemisphere mode of thinking. On the basis of a paper-and-pencil test presumably measuring hemisphere preference (Preference Test; Zenhausern, 1978), normal subjects (N = 75) were assigned to a group characterized by a left hemisphere thinking style, a group characterized by a right hemisphere thinking style and a group with mixed tendencies (left and right hemisphere tendencies). Additionally, subjects completed the Fear Questionnaire and the Depression Symptom Inventory. It was found that subjects with a right hemisphere thinking style reported more depressive and fear symptoms than subjects with a left hemisphere thinking style. This finding is in line with theories which assume that the right hemisphere is characterized by a negative, dysphoric emotional tendency.

Replication micrography of ammonium perchlorate surfaces during their initial stages of thermal decomposition

The textural modifications that occur during the initiation, establishment and development of growth product nuclei in the thermal decomposition of ammonium perchlorate have been investigated by a replication technique which provides information concerning sub-surface structural changes. Soon after attaining reaction temperature, (001) crystal faces develop residual saucer-like hemispherical depressions ascribed to bubble formation during water loss from superficial layers. Subsequently small holes develop, which penetrate into the crystal, together with regions containing parallel-oriented surface ridges. The subsurface morphology of the holes shows branching below the surface, possibly guided along subsurface dislocations. From examinations of replicas of growth nuclei it was concluded that intranuclear pores were continuous, interconnected and tortuous. We postulate that during the very early stages of decomposition on crystal faces a superficial liquid-like layer is formed containing Cl 2O 7 and some water. Some water is volatilized and, within the depressions of the retextured surface, reaction occurs preferentially to yield small, possibly fluid, aggregates of reactive species that penetrate the crystal surface. Reaction in these zones is self-sustaining, exothermic and involves the active intermediate, NO 2ClO 4.

On the theory of magnetometric resistivity (MMR) methods

The Magnetometric Resistivity (MMR) method is based on the measurement of the low‐level, low‐frequency magnetic fields associated with noninductive current flow in the ground. A component of the magnetic field is measured in the vicinity of one or more grounded electrodes. Recently, the method was tested successfully in the field. The present paper presents the theoretical basis of the method in a unified format. Part of the material is derived from valuable published papers which are difficult to obtain. The remainder of the paper contains original unpublished theoretical results. It is shown that a horizontally layered earth yields no MMR anomaly. The characteristic anomalies for an anisotropic earth, vertical and dipping contacts, thin and thick dikes, and semicylindrical and hemispherical depressions, as well as alpha media are presented in detail. There are two factors which influence the MMR anomaly; geometry and conductivity contrast. For many models, it is possible to separate these two effects. Type curves are presented for very large conductivity contrasts to illustrate the effect of geometry only. Ancillary curves enable finite conductivity contrasts to be deduced from field data.

Leukokeratosis nicotina glossi — smokers' tongue

“Leukokeratosis nicotina glossi” or “smokers' tongue” is a homogeneous leukoplakia with evenly distributed pin-point hemispherical depressions. Histologically, there is a loss of glossal papillae, hyperkeratosis, acanthosis and the formation of large drop-shaped rete pegs with central clefting and occasional parakeratotic plugging. Mitotic activity and atypia are not marked and there is no evidence of Candida species infection. In some respects the lesion histologically resembles verrucous carcinoma but, unlike that condition, papillomatosis is not clinically noticeable and an invasive “leading edge” is not apparent. All but one of the subjects in which the lesion was seen were men, all had concurrent leukokeratosis nicotina palati and two gave histories of laryngeal carcinoma.

Mineral variation in anorthositic, troctolitic, and adamellitic rocks of the Barth Island layered structure in the Nain anorthosite complex, Labrador

The Barth Island layered structure is an oval, 6 by 9 km body, consisting of rhythmically layered adamellitic rock in the center which grades outward through jotunite into troctolite. Farther outward the sequence repeats itself in reversed order, strongly reduced in magnitude and finer grained; the adamellitic zone is followed by jotunite which grades into coarse-grained leuconorite and into anorthosite of the Nain complex. The Barth Island structure, having an inverted conical base topped by a hemispherical depression, seems to represent a distorted sequence of rock layers with troctolite at the bottom, grading upward into adamellitic rocks which grade into anorthosite at the top. Trend-surface analysis demonstrates the regional variation of plagioclase and orthopyroxene compositions in the troctolite—adamellite sequence of the central part of the structure. The fits for the second- and third-degree surfaces are good and significant at the 99 percent level. The regression line for compositional variation in coexisting plagioclase and orthopyroxene in all analyzed rocks has a correlation coefficient of r2 = 0.78. The difference between the trends in the troctolite—adamellite sequence and the anorthosite—adamellite sequence is insignificant. The regression curve for compositional variation in coexisting orthopyroxene and olivine has a correlation coefficient of r2 = 0.98. The curve shows good correlation with the experimentally established partitioning curve of Medaris, which indicates that equilibrium conditions prevailed during formation of the olivine—ortho-pyroxene pairs. The results suggest that the troctolite—adamellite sequence and the anorthosite—adamellite sequence are products of fractional crystallization, possibly from the same parental magma.

Effects of shock intensity on transfer of shock avoidance under unilateral spreading depression

Rats trained on an active avoidance task under unilateral spreading depression typically show no transfer when trained with the contralateral hemisphere depressed. The lack of transfer could be due to the necessity of neocortex for learning this task or due to stimulus factors associated with left or right hemispheric depression. In the current study rats were trained on an active avoidance task under high (1.3 ma) or low (0.6 ma) shock. The high shock group showed marked transfer and the low shock group showed no transfer. The data indicate that the cortex is not needed for learning this task, but functions mainly to increase the sensitivity of the animal to external stimuli.

A Compact Radial Shearing Interferometer Based on the Law of Refraction

A brief review of radial shearing interferometers as well as a logical development of various types of these interferometers is presented. The discussion considers two types of interferometers. One type essentially introduces a radial shear in collimated light while in the other type a radial shear is introduced in converging light. Finally, a compact interferometer is described. This interferometer uses the Snell’s law of refraction for obtaining radial shear and consists of two identical prisms which make up a pentaprism. In one of the prisms, a hemispherical depression is made, and this is the basic element that introduces radial shear.