Gulls and Aircraft

1978 ◽  
Vol 5 (4) ◽  
pp. 277-280 ◽  
Author(s):  
Victor E. F. Solman
Keyword(s):  
Fast Moving ◽  
Insect Population ◽  
Considerable Proportion ◽  
Food Wastes ◽  
Jet Engines ◽  
Mouse Population ◽  
Early Autumn ◽  
Large Numbers

Birds, struck during flight by fast-moving modern aircraft or getting ingested in jet engines, cause numerous serious accidents of which some involve human deaths. Gulls of various species are the birds involved in a considerable proportion of these accidents due to bird-strikes.Gull-strikes of aircraft in flight may be expected:1. When there is a chronic attraction such as a concentrated worm or insect population, a high mouse population, or some other biological attractant;2. When there is lack of care in disposal of food-wastes;3. When drainage on an airfield or on flat-roofed buildings is not properly designed or is not functioning well; or4. During the early autumn when large numbers of inexperienced, immature gulls are in flight.

Asia in the Gunpowder Revolution

2018 ◽  
Author(s):  
Scott C. Levi
Keyword(s):  
Central Asia ◽  
Fast Moving ◽  
New Technologies ◽  
New Technology ◽  
The West ◽  
Multiple Factors ◽  
Cultural Preferences ◽  
Recent Scholarship ◽  
Large Numbers ◽  
Ming And Qing Dynasties

Contrary to long-held notions that gunpowder weapons technologies were devised in the West and gradually transmitted eastward into Asia, more recent scholarship indicates that innovations flowed in both directions. Scholars have also come to recognize that there was no uniformity in the ways that states implemented gunpowder weapons, and that multiple factors relating to environment, demographics, and cultural preferences informed decisions about when and how to embrace the new technology. The major Asian agrarian states of the Ottomans, Safavids, and Mughals (the so-called Gunpowder Empires) and the Ming and Qing dynasties in China implemented gunpowder weapons differently. The Ottomans were the most aggressive in this regard, the Mughals preferred a hybrid force, and the Safavids long favored cavalry. Chinese militaries employed hybrid forces to great effect, but in later years a lengthy peace during the Qing era slowed the implementation of new technologies. In Central Asia and other places where rulers could rely on large numbers of well-trained, fast-moving mounted archers and a nearly endless supply of horses, they found little reason to rush to embrace what for several centuries represented an expensive, slow, and unreliable technology.

“Parthenogenesis” in Schistosoma mattheei

1969 ◽  
Vol 43 (1-2) ◽  
pp. 197-206 ◽  
Author(s):  
M. G. Taylor ◽  
M. B. A. Amin ◽  
G. S. Nelson
Keyword(s):  
Reproductive Isolation ◽  
Experimental Studies ◽  
Biological Significance ◽  
Considerable Proportion ◽  
Mixed Infections ◽  
Transmission Potential ◽  
Single Sex ◽  
Large Numbers ◽  
Rectal Biopsies ◽  
Full Maturity

Experimental studies in mice have shown that with single sex female infections of S. mattheei there is a slow maturation of the worms with evidence of incomplete parthenogenesis; at 9 weeks no eggs were produced but at 17 weeks there was an average of 500 eggs per mouse. These were all non viable. Under similar conditions S. mansoni females failed to produce eggs.When the females of S. mattheei were paired with males of S. mansoni, the females reached full maturity and produced large numbers of eggs typical of their own species-many of the eggs were non viable but some contained active miracidia.It is considered that this is an example of parthenogenesis and not hybridisation. Cross specific pairings of schistosomes must occur frequently in man particularly with S. haematobium, S. mansoni and S. mattheei and this phenomenon could be of considerable clinical, epidemiological and biological significance. Parthenogenesis in mixed infections probably accounts for the large number of non-viable S. haematobium eggs seen in rectal biopsies, and it may also be important in reducing the transmission potential of schistosomes to man since cross pairing must result in the “sterilisation” of a considerable proportion of the female worms in mixed infections. This phenomenon may also explain the observed reproductive isolation of schistosome species which simultaneously infect the same host.

scholarly journals Field evidence of intra- and interspecific predation in rock-pool corixids (Heteroptera, Corixidae)

1992 ◽  
Vol 3 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Irmeli Pajunen ◽  
V. Ilmari Pajunen
Keyword(s):  
High Mortality ◽  
Developmental Stages ◽  
Field Conditions ◽  
Considerable Proportion ◽  
Rock Pool ◽  
Field Evidence ◽  
Large Numbers ◽  
Interspecific Predation

Small corixid larvae were introduced into a rock-pool containing large numbers of later developmental stages. High mortality of small larvae was observed. A considerable proportion of larval carcases recovered each had triangular holes on its upper surface. Similar holes are characteristic of carcases recovered in laboratory cannibalism experiments. The dimensions of the punctures in field and laboratory samples match closely. Predatory interactions between large and small rock-pool corixid larvae are thus common in field conditions.

Air Traffic Control and the Jet Aeroplane

1952 ◽  
Vol 5 (1) ◽  
pp. 55-63 ◽  
Author(s):  
D. O. Fraser
Keyword(s):  
Fuel Consumption ◽  
Traffic Control ◽  
High Speed ◽  
Maximum Efficiency ◽  
Turbine Engines ◽  
Considerable Proportion ◽  
Jet Engines ◽  
Inherent Feature ◽  
Great Leap Forward ◽  
The Great Leap Forward

The fact that the de Havilland Comet cruises at nearly double the flying speed and nearly double the flight altitude of comparable piston-engined airliners is a measure of the great leap forward in air transport which the introduction of gas-turbine engines has brought about. It also illustrates an inherent feature of jet aircraft, for only at high speed and high altitude do turbo-jet engines, and to a less critical extent turbo-prop engines, operate at their maximum efficiency, expressed in distance flown per gallon of fuel consumed. With reduction of altitude and speed, however, the fuel consumption does not fall off proportionately and efficiency decreases rapidly. For example, even when taxying on the ground the Comet's fuel consumption is about 70 per cent of that at cruising altitude, and when flying at sea level the still-air distance flown on a given quantity of fuel is less than half of that at cruising altitude. In other words you get the best out of a jet aircraft when you are going somewhere fast, and when the length of the flight is sufficient for the aircraft to climb to its optimum cruising altitude and remain there for a considerable proportion of the flight time.

Ecology and evolution of sympatric sticklebacks (Gasterosteus): spatial segregation and seasonal habitat shifts in the Enos Lake species pair

1984 ◽  
Vol 62 (12) ◽  
pp. 2436-2439 ◽  
Author(s):  
P. Bentzen ◽  
M. S. Ridgway ◽  
J. D. McPhail
Keyword(s):  
Littoral Zone ◽  
Vancouver Island ◽  
Adaptive Significance ◽  
Spatial Segregation ◽  
Species Pair ◽  
Benthic Species ◽  
Late Autumn ◽  
Early Autumn ◽  
Large Numbers ◽  
Oxygen Cycle

A pair of stickleback species (Gasterosteus) coexist in Enos Lake on Vancouver Island. Spatial segregation between species and seasonal habitat shifts were investigated by means of monthly surface and bottom samples. During the summer there was clear spatial segregation; both sexes of the benthic species were inshore, reproductive males of the limnetic species were also in the littoral zone, and adult limnetic females and nonbreeding males were at the surface. There were also seasonal habitat shifts. Benthics of both sexes moved onshore in the spring and remained throughout the summer. In the autumn, after the lake turned over, large numbers moved offshore to deeper water and appeared to disperse. It is suggested that this shift in the benthic species is an adaptation to the seasonal oxygen cycle in the hypolimnion. The limnetic species appeared at the surface in spring and remained there throughout the summer and early autumn. In late autumn they disappeared from the surface and did not reappear until next spring. During the winter small numbers were taken in bottom traps. Apparently limnetics move away from the surface during the winter. The adaptive significance of this shift remains unclear.

New Approach to the Inspection of Cooling Holes in Aero-Engines

2006 ◽  
Author(s):  
Devdas Shetty ◽  
Tom Eppes ◽  
Nikolai Nazaryan ◽  
Jun Kondo ◽  
Claudio Campana
Keyword(s):  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Inspection System ◽  
Jet Engines ◽  
Optical Inspection ◽  
Large Numbers ◽  
Data Acquisition Software ◽  
Blade Failure ◽  
Aero Engines

The need for improved thermal efficiency of jet engines has led to changes in the design of combustor turbine blades. Modern turbine stage inlet temperatures now exceed the melting point temperatures of turbine blade materials. Super alloys, based on nickel, have been developed for use as blades, guide vanes, afterburners etc. To combat and avert blade failure caused by excessive operating temperatures, film cooling has been incorporated into blade design. In film cooling, cool air is bled from the compressor stage, ducted into internal chambers of the turbine blades, and discharged through small holes in the blade walls. This provides a thin, cool, insulating blanket along the external surface of the turbine blade. Large numbers of shaped holes have allowed designers to maximize the cooling effect. This paper explores a new design for measuring the presence and depth of blind holes in turbine blade. In the paper, we examine the inspection techniques currently in use and present a novel optical technique as an alternative. To precisely control the location of the holes on the turbine blade, an XYZ inspection stage is employed. Using a small collimating tube, a micro-beam illuminates each hole in a pre-programmed fashion. Depending on the level of reflected intensity and when it occurs, the presence of a hole bottom is determined. The optical inspection system consists of a laser, motorized micropositioning stage, collimating tubes, data acquisition software and a customized fixture for manipulating the samples.

Cytoplasmic Granules in Lymphocytes from Rats Dosed with SK&F 14336-D

1971 ◽  
Vol 29 ◽  
pp. 556-557
Author(s):  
T. G. Merrill ◽  
B. J. Payne ◽  
A. J. Tousimis
Keyword(s):  
Lipid Storage ◽  
Pokeweed Mitogen ◽  
Electron Microscopic ◽  
Cytoplasmic Granules ◽  
Storage Diseases ◽  
Tay Sachs Disease ◽  
Large Numbers ◽  
Microscopic Studies ◽  
Neurovisceral Lipidosis

Rats given SK&F 14336-D (9-[3-Dimethylamino propyl]-2-chloroacridane), a tranquilizing drug, developed an increased number of vacuolated lymphocytes as observed by light microscopy. Vacuoles in peripheral blood of rats and humans apparently are rare and are not usually reported in differential counts. Transforming agents such as phytohemagglutinin and pokeweed mitogen induce similar vacuoles in in vitro cultures of lymphocytes. These vacuoles have also been reported in some of the lipid-storage diseases of humans such as amaurotic familial idiocy, familial neurovisceral lipidosis, lipomucopolysaccharidosis and sphingomyelinosis. Electron microscopic studies of Tay-Sachs' disease and of chloroquine treated swine have demonstrated large numbers of “membranous cytoplasmic granules” in the cytoplasm of neurons, in addition to lymphocytes. The present study was undertaken with the purpose of characterizing the membranous inclusions and developing an experimental animal model which may be used for the study of lipid storage diseases.

Prolonged Fixation Studies For Spaceflight

1973 ◽  
Vol 31 ◽  
pp. 332-333
Author(s):  
Robert Corbett ◽  
Delbert E. Philpott ◽  
Sam Black
Keyword(s):  
High Pressure ◽  
Living Systems ◽  
Prolonged Storage ◽  
Time Intervals ◽  
Early Signs ◽  
Large Numbers

Observation of subtle or early signs of change in spaceflight induced alterations on living systems require precise methods of sampling. In-flight analysis would be preferable but constraints of time, equipment, personnel and cost dictate the necessity for prolonged storage before retrieval. Because of this, various tissues have been stored in fixatives and combinations of fixatives and observed at various time intervals. High pressure and the effect of buffer alone have also been tried.Of the various tissues embedded, muscle, cartilage and liver, liver has been the most extensively studied because it contains large numbers of organelles common to all tissues (Fig. 1).

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

Selective Sampling and Orientation of Non-Homogeneous Tissues

1968 ◽  
Vol 26 ◽  
pp. 98-99
Author(s):  
C. C. Clawson ◽  
L. W. Anderson ◽  
R. A. Good
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Random Sampling ◽  
New Method ◽  
Microscope Examination ◽  
Small Areas ◽  
Selective Sampling ◽  
Large Numbers ◽  
Specific Orientation

Investigations which require electron microscope examination of a few specific areas of non-homogeneous tissues make random sampling of small blocks an inefficient and unrewarding procedure. Therefore, several investigators have devised methods which allow obtaining sample blocks for electron microscopy from region of tissue previously identified by light microscopy of present here techniques which make possible: 1) sampling tissue for electron microscopy from selected areas previously identified by light microscopy of relatively large pieces of tissue; 2) dehydration and embedding large numbers of individually identified blocks while keeping each one separate; 3) a new method of maintaining specific orientation of blocks during embedding; 4) special light microscopic staining or fluorescent procedures and electron microscopy on immediately adjacent small areas of tissue.

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