Narrow Entrance Research Articles

Spectroscopy with Copernicus and the Edwin P. Hubble Observatory

It is a pleasure and a privilege for me to participate in this symposium in honor of Professor Rowland. My talk will deal with astronomical applications of spectroscopy, and will have two parts. First, I shall talk about the Copernicus satellite, mainly because it used a Rowland spectrometer, which was uniquely qualified for the purpose we had in mind. Second, I shall say a few words about the two spectrometers on the Hubble Space Telescope; these instruments do not use Rowland mountings, but are of interest because they offer such enormous promise for future research. MY own interest in spectroscopy emphasizes the ultraviolet wavelengths, because in the study of interstellar matter the universe opens up below 3000 A. It opens up a little wider below 1600 A, and even more in the region between 900 and 1250 A, the region in which the Copernicus satellite principally contributed to the study of interstellar lines. Fiqure 1 is an optical diagram of the spectrometer on Copernicus, which will be familiar in principle, I am sure, to all of you. The light passes through a narrow entrance slit and strikes the concave grating: the spectrum is then brought to a focus on the Rowland circle, about one meter in diameter. I shall say nothing about the Copernicus spacecraft, but I will say just a few words about the spectrometer exit slits, since these were of somewhat unusual design.

The development of the plasma membrane reticular system in the fat body of an insect

Several insect tissues have plasma membranes that are folded inwards to make a subsurface reticulum on faces that are exposed to hemolymph. The infolds have been called plasma membrane reticular systems (RSs) to distinguish them from the somewhat similar structures found in transporting epithelia. They are characterized by having negative charges on the plasma membranes of the entranceways and by the concentration of some hemolymph proteins in their lymph spaces. Their formation and loss in the fat body has been studied by scanning electron microscopy during the fifth stadium of Calpodes ethlius (Lepidoptera, Hesperiidae). Fat body cells begin the fifth stadium arranged in ribbons with the cells linked together by a fringe of processes. In the first stage many more processes form. These partially fuse together in the second stage, leaving a subsurface reticulum connected by narrow entrances to the lateral cell faces and the face below the basal lamina. Both the cell processes and the reticular systems that they enclose are usually axially orientated. The completed RS persists for the second half of the intermoult devoted to larval syntheses when the concentration of hemolymph proteins rises. After protein sequestration prior to pupation the RS is lost and the fat body returns to being a tissue of rounded cells linked by a few enmeshed processes.

A hydraulic experiment on tidal exchange

Tidal exchange through a narrow entrance channel was studied experimentally with the use of a simplified hydraulic model. The inflowing water mass, visualized with dye solution, exhibits the shape of a starting plume with a starting vortex pair at its head. Because of their periodical formation by the tide, these are called the “tidal plume” and “tidal vortex pair”. The axis of the tidal plume deflects and undulates with a period 2 to 9 times that of the tide. Together with this undulation, the vortex pair becomes asymmetric. A circulating flow is formed in the bay which affects the shape of the inflowing and outflowing water masses. A part of the inflowing water mass flows out during the subsequent ebb, and this outflowing portion can be divided into two parts. One is the water remaining in the entrance channel at high water which flows out during the first half of the subsequent ebb and the other is the water flowing round the bay in the circulating flow during flood that flows out during the latter half of the subsequent ebb. Both contribute to the exchange ratio, but we can estimate an upper limit for the exchange ratio by neglecting the latter outflow. This neglected portion is considered in the concept of the age composition of outflowing water. The age composition of the bay water shows the existence of intermittent effluence superposed on a trend in the age composition that is similar to that of the well-mixed case. From the analysis of a model consisting of a number of mixing tanks connected in series with a recycle flow, it is concluded that this intermittent effluence occurs in the case of weak mixing due to the effect of circulating flow in the bay but is negligible in the case of strong mixing.

Temperature Distributions in Tidal Flow Field

The development and application of a numerical model to predict the two‐dimensional depth mean velocity fields and background temperature distributions in a natural harbor, at Poole, England, is described. The predicted background temperature rises resulted from the proposed siting of either a 700 or 350‐MW capacity power station on the harbor perimeter, with the intake and outfall for the cooling water system being located along the boundary and within the harbor, respectively. The numerical model was based on the solution of the depth‐integrated flow equations, simulating the tidal currents, and on the depth integration of the advective‐diffusion equation for the conservation of heat. The main difficulties encountered in the hydrodynamic model included the representation of the advective acceleration terms, particularly since the harbor had a narrow entrance, and the modeling of the significant changes, which occur in the plan cross‐sectional area as large regions of shallow water, were dried out and flooded on each tide. The modeling difficulties associated with the heat balance equation included the numerical treatment of the temperature discontinuity at the outlet and the open seaward boundary conditions.

Tidal residual circulation produced by a tidal vortex

The role of the ‘tidal vortex’ in the mechanism of generation of tidal residual circulation is investigated for a bay with a narrow entrance channel. It is shown that the circulation of residual flow is produced not by the vorticity of the inflowing sidewall-boundary layer, but by a tidal vortex formed by rolling up of the discontinuity surface released from the flow separation point at the entrance. This tidal vortex is affected by the circulation of the inflowing water, that is the inflowing tidal vortex. A returning tidal vortex formed in the bay diminishes the circulation of the tidal vortex of the next generation, while the inflowing tidal vortex formed in the open sea increases it. These cases correspond to tidal vortex life-histories of type-II and type-III, respectively (Kashiwai, 1984a). Tidal vortices of each life-history type have different strength and produce residual circulation of different strength, corresponding to each type. The ratio of kinetic energy of residual flow to that of the tidal current through the bay entrance, that is to say the energy gain of the residual circulation, is proportional to the reciprocal of the Strouhal number, and its rate of increase depends on the life-history type of the tidal vortex. This explains the experimental observation reported by Oonishi (1977) and Yanagi (1978) that the energy ratio of residual flow to tidal flow increases with the Reynolds number not monotonously but goes through a maximum and a minimum at intermediate Reynolds number.

Nakanoumi Land Reclamation and Freshening Project

Lake Nakanoumi is a shallow coastal lagoon connected with the Japan Sea only by a narrow channel. The Nakanoumi Land Reclamation and Freshening Project was started in 1963. The objectives of this project were to reclaim agricultural lands of 25 km2 from Lake Nakanoumi and to convert the remaining water basin of some 3.6 × 108 m3 into a fresh-water reservoir by damming its narrow entrance. However, socio-economic conditions have drastically changed since the late 1960's. The originial plan of agriculture in newly reclaimed lands had to be changed because of a rice overproduction since 1967 and the future land-use plan has not yet been determined. It was widely appreciated in the 1970's that a natural environment was indispensable for human life. Under these circumstances local people began to raise cries for reconsideration of the project which seemed to lose its original purpose and significance. Until now the full enclosure of Lake Nakanoumi has not been started, despite the completion of a tidal gate in 1974. An inter-disciplinary approach becomes increasingly more necessary to solve the problem.

Receptor-mediated endocytosis in cultured fibroblasts: cryptic coated pits and the formation of receptosomes.

Concentrative receptor-mediated endocytosis of many specific ligands by cultured fibroblasts occurs through the coated pit-receptosome pathway. The formation of receptosomes was studied using two impermeant electron-dense labels for the cell surface, ruthenium red and concanavalin A-horseradish peroxidase. These studies show that at 4 degrees C, virtually all coated structures near the plasma membrane are in communication with the cell surface, and are not isolated coated vesicles. On warming cells to 37 degrees C for only 1 minute, a major portion of these structures become cryptic, that is, not labeled by these surface markers. However, on cooling cells immediately back to 4 degrees C, virtually all of these structures are again in communication with the surface. Many images showed that membrane of these cryptic pits to be continuous with the cell surface when caught in the appropriate plane of section; often there was a very narrow entrance that excluded extracellular label. At 37 degrees C, receptosomes could be occasionally seen forming as an invagination of membrane adjacent to the coated region. Mechanisms by which receptosomes may form and other evidence demonstrating the failure of coated pits to pinch off to form isolated coated vesicles during endocytosis are discussed.

Numerical Modeling of Tidal Circulation in Harbors

In this study a numerical model has been developed that can be used to predict the two-dimensional tide-induced velocity fields in harbors and estuaries. The model is particularly suited to basins having a narrow entrance where, on the incoming tide, the divergence of the velocity field associated with the jet inlet gives rise to the generation of vorticity. The time-dependent nonlinear equations of motion are formulated to include the effects of bottom roughness, wind action, the earth's rotation, and a simplified version of the turbulent transfer of momentum. These equations are expressed in an alternating-direction implicit finite difference form and are solved by Gaussian elimination. The numerical model has been checked by making comparisons between the computed velocity fields and experimentally measured velocities and path lines for two hydraulic model studies involving various rectangular harbors and a circular reservoir.

Ontogeny, function and evolution of extreme floral construction inMonimiaceae

In at least 4 genera of theMonimiaceae (Tambourissa, Wilkiea, Kibara, Hennecartia) extremely specialized flowers with a hyperstigma occur, i.e. a secretory zone in the narrow entrance of the floral cup. The mucilaginous secretion of the hyperstigma and of the carpels produces a transmitting medium for pollen tubes continuous from the mouth of the floral cup to the ovules. As to their floral morphology, the two extreme types,Hortonia andTambourissa, are connected gradually by various other genera. Possible evolutionary trends and systematic problems are outlined.

Surface area and pore structure of hydrothermal reaction products of granulated blast furnace slag

Specific surface areas and pore structure studies were carried out on autoclaved slag-lime and slag-quartz-lime pastes. Autoclaving temperatures were 181 and 213°C. Water and nitrogen adsorption isotherms were measured and their results are comparatively discussed. The specific surface areas measured by water were appreciably higher than the nitrogen surface areas, whereas the total pore volumes measured by water were found to be smaller. A probable explanation was given to this unexpected behaviour, based mainly on the interaction between the polar water molecule and the ionic surface, which takes place in a pore structure with narrower entrance way than inside pore size. This interaction might interfere with the further adsorption, blocking the entrances to further capillary condensation of water vapour.

POLLEN TRANSFER AND POLLINATION IN THE COMMON FIG (FICUS CARICA L.)

SummaryThe traditional ideas, as to how pollination is achieved in the common fig (Ficus carica L.), are untenable because the very narrow entrance slits of the ostiole render it very difficult for the pollen vector (the agaonid wasp Blastophaga psenes L.) to introduce pollen on its body surface into the female receptive fig. The process is now shown to entail: (a) loading of pollen in the polleniferous fig into intersegmental and pleural invaginations which form in the shrunken body of the wasp following water loss; (b) unloading of pollen in the receptive fig, as a result of partial swelling and contortion of the wasp's body during oviposition attempts. Conditions in the cavities of polleniferous and receptive figs are discussed in connection with the pollination process.

The influence of the ionizing irradiation on the capillary condensation hysteresis

An influence of the X-ray irradiation on adsorption hysteresis of water was found. This effect can be explained by the formation of the nuclei in the metastable adsorbate. It appears only in pores with narrow entrances and large cavities at relative pressures corresponding to the negative pressures in the condensed phase that are greater than ∼ 500 atm.

Channel Friction and Slope Effects on Harbor Resonance

An approximate matching technique uses separate solutions in a semi-infinite ocean bounded by a straight coastline, a harbor basin, and a narrow straight entrance channel which connects them. Wave height and velocity are matched at the interfaces. Such an approach allows different solutions to be used in any of the three regions, when the physical description of that region is modified, without changing the solutions used in the remaining regions. In the present work, the entrance channel is first considered to possess a wall/bottom friction although the remaining regions are kept frictionless. Results indicate that the channel effect, which leads to increasing resonance amplification with increasing channel length analogous to the well-known harbor paradox, is counteracted by the increase in frictional effects for a longer channel. The second problem considered modified the entrance channel to have a linear slope from a constant depth ocean to a harbor basin at some other constant depth.

Broadening of Fast-Beam Spectral Lines Due to Diffraction at the Entrance Slit of a Spectrometer

We show experimentally and theoretically that adjustment of a spectrometer for observation of fast-beam spectral lines under conditions of minimum linewidth requires consideration of the effects of diffraction at the spectrometer's entrance slit. We obtain an approximate expression for the optimum entrance slit width to be used in order to avoid the pronounced broadening of the spectral lines that occurs for very narrow entrance slits.

Densities of coals measured with various liquids

The densities of vitrains of twelve Japanese coals and five foreign coals were measured in methanol, n-hexane and mercury at 25 °C using a vacuum apparatus. All the densities showed higher values in lower and higher rank coals and minima at about 87% carbon content. The pore volumes deduced from the differences between the specific volumes measured in the liquids and in helium, and from carbon dioxide adsorption, are discussed and compared. It seems that the micropore diameter or entrance diameter is small in the lower and higher rank coals, and shows a minimum at about 87% carbon content. The ease of accessibility of molecules to the micropores of coals decreased in the order methanol, carbon dioxide and helium. The excess of density in methanol over that in helium is too large to be interpreted only by contraction of methanol in the pores of coal. It is suggested that helium may be restricted in penetrating very narrow pore entrances by the activated diffusion effect, while methanol can penetrate into these pores by virtue of an imbibition effect. The volume of micropores accessible to methanol but inaccessible to carbon dioxide is directly proportional to the content of hydroxyl groups.

Pore structure analysis by water vapor adsorption. IV. Analysis of hydrated portland cement pastes of low porosity

The pore volume and surface distributions of 25 hardened pastes of a hydrated portland cement were determined by water vapor adsorption isotherms. The water to solid weight ratio, w s , used in the preparation of 21 pastes was 0.2, and of 4 pastes it was 0.3. The w s ratio determines the porosity of the paste, and such pastes as are discussed in the present paper are called low-porosity pastes. In the analyses, the two new methods developed by Brunauer and his coworkers were used: the “MP-method” for the micropores, and the “corrected modelless” method for the wider pores. Of the 25 pastes, 8 were previously analyzed by nitrogen adsorption isotherms, using the same methods. Comparison of the water vapor and nitrogen results showed that nitrogen could not penetrate into the micropores, and it could penetrate only into a small fraction of the wider pores. This indicates the presence in low-porosity pastes of very many “ink-bottle” pores, i.e., pores having wide bodies and narrow entrances. The analyses were based on the adsorption isotherms. Desorption equilibration takes very long times, and the indication from the isotherms, as well as from earlier work, was that, given adequate time, very small hysteresis loops would be obtained, or none at all. The pore structure results based on the adsorption branch satisfied the two criteria of correct analysis very well: the cumulative pore surface agreed with the BET surface, and the cumulative pore volume agreed with the uptake of water at the saturation pressure. This is what one would expect for adsorbents which contain predominantly ink-bottle pores. The results showed that with progressing hydration micropores were formed at the expense of wider pores. From one-half to three-fourths of the surface area was located in micropores. The pore volume distribution curves showed that the temperature of hydration had little or no effect on the pore structure. The pastes prepared with w s = 0.3 had a larger pore volume in each pore group than those made with w s = 0.2 , but the distribution of the volume in pores of different sizes was similar for the two w s ratios. The compressive strengths of the pastes were found to depend not only on the degree of hydration and total porosity but also on another factor, which may be the pore volume distribution. The micropores appeared to have a greater effect on the reduction of strength than the wide pores.

Energy Analysis of Small Angle Diffraction Patterns in Aluminum Films

One method of investigating the spectral and spatial distribution of the energy lost by the image-forming electrons in an electron microscope uses a dispersive field to form an energy spectrum perpendicular to the length of a narrow entrance slit, mounted below the viewing screen of the microscope. The slit width determines the kind of experiments that can be performed, in that there is generally an upper limit on photographic exposure times due to instrumental instabilities and specimen contamination. A recently built version of this type of instrument uses a Wien filter to form a focussed dispersive image of the electron distribution at the entrance slit. The principle advantage of the system over the Möllenstedt analyser is that the slit can be made much wider (250μm) for the same energy resolution. This gain in intensity has allowed us to examine the energy losses in the smallangle diffraction region around any intense beam in a diffraction pattern.

Jamdat Nasr fund fra Oman

Jamdat Nasr fund fra Oman

Feeding of Western and Semipalmated Sandpipers in Peruvian Winter Quarters

LARGE numbers of shorebirds that breed in North America spend the winter in the region of the Bay of Paracas, 150 miles south of Lima, Peru. During a short period in October and November 1965 I had the opportunity to observe some aspects of the feeding behavior of mixed flocks of two very similar species, the Semipalmated Sandpiper (Ereunetes pusillus) and the Western Sandpiper (E. mauri), which has a considerably longer bill. They were feeding in a small harbor-like inlet with a narrow entrance, situated at La Puntilla, Pisco, about 2 miles north of the Bay of Paracas. The tides caused important changes in this habitat, and these varied considerably from day to day; the lowest tides virtually emptied the inlet, while the highest of the low tides left the inlet bottom at least one third covered with water. At low tide, three zones could be distinguished; water, wet mud (shiny), and dry mud (dull). These zones are presumably equivalent respectively to zones D and E, zone B, and zone A in Figure 3 in Recher's study of the feeding of shorebirds (Ecology, 47: 393-407, 1966). The extent of the three zones changed continually as the water flowed in and out of the inlet, and as wet mud dried on the outgoing tide and dry mud became wet mud on the incoming tide. The numbers of birds in the inlet varied from day to day; in late October and the first half of November there were usually between 20 and 100 Semipalmated Sandpipers (average 33) and between 3 and 40 Western Sandpipers (average 8). The Western Sandpipers were frequently in two or three loose groups within the flock of Semipalmated Sandpipers, and the two species fed over the same general area, frequently only a meter or so apart. I noticed only occasional interor intraspecific aggression. My objective was to determine the extent to which these two species differ in their exploitation of the feeding habitat. As close as possible to the time of low tide, I made a series of counts of the flock in quick succession, noting first how many of each species were in water, then how many were on wet mud, and finally how many were on dry mud. Birds at the boundaries of the defined substrates were ignored, for instance birds standing on wet mud but feeding in water. These counts were repeated several times on each of 6 days. The totals for each day (Table 1) show that on most days the highest percentage of both species fed on wet mud. On all days the Western Sandpiper tended to be relatively more abundant in water, and the Semipalmated Sandpiper to be more abundant on dry mud. The consistency of this trend indicates a real difference in zone

The Legal Regime of Russian Territorial Waters

Several elements have interacted to influence the course and pattern of the boundaries and the regime of Soviet territorial waters. The foremost of these is national security. All of the seas bordering the U.S.S.R. have narrow entrances which can be commanded easily by hostile foreign Powers. During the Russian Revolution and subsequent Civil War, German vessels and, after the War, Allied vessels in the Baltic and the Dardanelles restricted to an uncomfortable extent the freedom of action of the Soviet Government. Soviet weakness in the Baltic theater was a major factor in determining Soviet policy towards Finland and the Baltic states during the 1939-1941 period, and the proximity of NATO naval forces to the Baltic continues to provoke Soviet proposals to close the sea to noncoastal Powers. Similarly, the U.S.S.R. was compelled to endure Turkish violations of the Montreux Convention on the Turkish Straits during World War II while its Black Sea fleet was immobilized. The Pacific coast seas and the Atlantic and Pacific approaches to the Arctic seas are also susceptible to a blockade by hostile Powers. Even the Arctic seas themselves, once regarded as an unguarded but impregnable frozen boundary, have become unexpectedly vulnerable with the development of nuclear submarines.