Sink Regions Research Articles

Interactions between Source, Path and Sink in Determining Phloem Translocation Rate

Treatments involving mild (5-10 Celsius degrees) temperature changes, spanning a range of mean temperatures, were imposed upon the source, path and sink regions of a translocating plant of Nymphoides geminata whilst the translocation rate was monitored. The temperature dependence (Q*10) of the rate of translocation was evaluated for each of these treatments. A new steady rate was achieved in only 3-5 min following a temperature change and was sustained for 2 h or more. Changes in rate were propagated down the sieve tubes at speeds more than ten times greater than those of sap flow, indicating that translocation involves the flow of a slightly compressible sap. The results suggest that translocation rate is normally under the joint control of source, path and sink regions of the plant. An attempt is made to assess their relative contributions to the overall control and this leads to the conclusion that, in this plant situation, the pathway predominates in controlling rate. It would seem that the individual rates of activity of source, path and sink regions are modulated by changes in the sieve tube sap concentration in their vicinity, these changes corresponding to, and being brought about rapidly by, changes in the hydrostatic pressure of this sap.

A Practical Diagram for Computing Long-line Effects for CW Magnetron

The mode skip of a magnetron under heavy load conditions can be reduced by connecting (he load through a long line, since the external Q of the magnetron at the sink region is increased by frequenc...

Input Impedance Measurement of Microwave Ovens

AbstractThis paper describes a method of measuring the input impedance of the microwave oven dynamically. The method uses the magnetron itself as a signal source instead of a fixed frequency generator used for static impedance measurement. The impedance of an oven can be determined correctly, particularly in the sink region of the magnetron load characteristics.

Plasmalemma transport of OH- in Chara corallina: dynamics of activation and deactivation.

The light-mediated, time-dependent rise in the pH value at the center of an alkaline band was analyzed using the methods of numerical analysis. From this analysis an expression of the time-dependent build-up of OH- efflux was obtained for these bands. This information can now be employed to determine whether the light-activated transport of OH- and HCO3- influences the electrical properties of the plasmalemma. The dark-induced deactivation of OH- transport was also characterized, revealing a transition from efflux to a transient influx phase during deactivation. Numerical analysis of the steady-state OH- diffusion pattern, established along the surface of an alkaline band, revealed that the OH- efflux width was wider than previously envisaged. It was also found the OH- sink regions exist on either side of the efflux zone. These, and other characteristics revealed by the numerical analysis, enabled us to extend the OH- transport model proposed by Lucas (J. Exp. Bot. 1975, 26:347).

Ice movement and distribution in the Bering Sea from March to June 1974

Ice distribution and motion in the Bering Sea from March to June 1974 were observed by imagery from the NOAA 2 and 3 VHRR (very high resolution radiometer) satellites. The southerly ice edge was nearly constant in position from March to mid-May, when ice disintegration had progressed to a point where the edge was undefined. Ice movement was southerly in response to northerly winds until late April, after which variable ice motion reflected variable winds. The southerly motion created regions of ice divergence south of islands and along east-west trending southern coasts. In some areas such as the Bering Strait, water motion exerted sufficient stress on the ice to balance the wind.stress, resulting in stationary ice or northerly ice motion. The Bering Sea ice cover is conceptualized as northern source and southern sink regions connected by an intermediate zone of southerly ice motion. A mean observed southerly ice motion of 18 cm s−1 requires heat losses for ice formation of the order of 10 g-cal m−2 s−1 or an order of magnitude greater if most ice is assumed to form in divergent areas covered by thin ice or that have open water. These values are in agreement with previous estimates of sea-air heat flux in the Arctic.

Origin of Marble by Replacement of Gypsum in Carbonate Breccia Nappes, Carson Sink Region, Nevada: A Discussion

Previous articleNext article No AccessDiscussion and ReplyOrigin of Marble by Replacement of Gypsum in Carbonate Breccia Nappes, Carson Sink Region, Nevada: A DiscussionKenneth A. Plumb and Marjorie D. MuirKenneth A. Plumb Search for more articles by this author and Marjorie D. Muir Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 84, Number 4Jul., 1976 Article DOIhttps://doi.org/10.1086/628215 Views: 1Total views on this site Citations: 1Citations are reported from Crossref Copyright 1976 University of ChicagoPDF download Crossref reports the following articles citing this article:ALASTAIR J. STEWART A barred-basin marine evaporite in the Upper Proterozoic of the Amadeus Basin, central Australia, Sedimentology 26, no.11 (Feb 1979): 33–62.https://doi.org/10.1111/j.1365-3091.1979.tb00337.x

Origin of Marble by Replacement of Gypsum in Carbonate Breccia Nappes, Carson Sink Region, Nevada

Sheets of carbonate breccia and unbrecciated calcitic carbonate rocks, called carbonate breccia nappes, occur as tectonic slices in nappe piles dominated by pelitic rocks of Early Mesozoic age in the Carson Sink region of Nevada. The most extensive carbonate breccia nappe, the Muttlebury nappe, crops out over 100 $$km^{2}$$. Such sheets are composites of a number of different carbonate rock types, including widespread calcite marble. The coarse grain size and granoblastic texture of the marble imply an origin by metamorphism of at least moderate grade. The degree of apparent recrystallization of marble, however, contrasts markedly with that of most of the limestone with which it is intercalated and is independent of degree of metamorphism, locally nil, of pelitic rocks in adjacent nappes. If the marble is a product of thermal metamorphism, its grade is seemingly incompatible with that of associated rocks. On the basis of field and petrographic studies, the origin of the marble is enigmatic. Carbon and oxy...

Carbonate Breccia (Rauhwacke) Nappes of the Carson Sink Region, Nevada

Research Article| April 01, 1975 Carbonate Breccia (Rauhwacke) Nappes of the Carson Sink Region, Nevada R. C. SPEED R. C. SPEED 1Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201 Search for other works by this author on: GSW Google Scholar Author and Article Information R. C. SPEED 1Department of Geological Sciences, Northwestern University, Evanston, Illinois 60201 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1975) 86 (4): 473–486. https://doi.org/10.1130/0016-7606(1975)86<473:CBRNOT>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation R. C. SPEED; Carbonate Breccia (Rauhwacke) Nappes of the Carson Sink Region, Nevada. GSA Bulletin 1975;; 86 (4): 473–486. doi: https://doi.org/10.1130/0016-7606(1975)86<473:CBRNOT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Nappe piles of lower Mesozoic pelite in the Carson region of Nevada contain sheet-like carbonate complexes (breccia, unbrecciated masses, minor gypsum), referred to as carbonate breccia nappes and the rocks within them collectively as rauhwacke, after similar rocks in the Alpine chains. In the Carson region, rauhwacke occurs only in nappe piles of pelitic rocks, suggesting that nappe tectonics and rauhwacke origin were related.The largest and most thoroughly studied carbonate complex, the Muttlebury nappe, consists of masses of deformed carbonate rocks, 2 m to 10 km in outcrop length, that are irregularly distributed through dominant carbonate breccia. The breccia, largely polymict and massive but locally stratified, is probably of intraformational origin. It is argued that rauhwacke of the Muttlebury nappe and elsewhere in the Carson region is derivative from detached masses of the Jurassic Lovelock Formation. Gypsum in the Lovelock Formation is believed to have been partially calcitized, yielding marble, the most abundant lithology of the Muttlebury nappe. Breccia is proposed to have originated by dissolution of gypsum that escaped calcitization and by subsidence and collapse of the intercalated carbonate rocks.The Muttlebury nappe was emplaced as the sole of a thick pelite nappe, perhaps contemporaneously with solution brecciation. After emplacement, both nappes were folded with their substrate. It is hypothesized that translation of the nappe pair depended on the low strength of the gypsiferous proto-Muttlebury nappe. As gypsum dissolved, the rheologic contrast of the Muttlebury nappe and its surroundings diminished, and translation of the nappe pair was progressively hindered. Once the proportion of solution breccia was sufficient, further displacement was taken up by folding. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Structural and Physiological Changes in Sugar Beet Leaves during Sink to Source Conversion

The onset of export during leaf development was correlated with changes in metabolism and ultrastructure and with patterns of solute distribution in the developing seventh leaf of sugar beet (Beta vulgaris L.) in order to study the cause of initiation of translocation. Infrared gas analysis of carbon dioxide uptake showed a broad peak for net photosynthesis dm(-2) at 35 to 40% final laminar length. Pulse labeling with (14)CO(2) demonstrated that maximum import of translocate occurred at 25% final laminar length; export was first observed at 35% final laminar length. Between 40 and 50% final laminar length a rapid increase in amount of export occurred, primarily as a result of the increase in the area of leaf which was exporting. Whole leaf autoradiography revealed that onset of phloem loading spread basipetally from the leaf tip; loading was initiated at about 22% final laminar length and was essentially complete by 50% final laminar length. Those areas which clearly exhibited loading no longer imported from other parts of the plant while the area in transition still appeared to import label from source regions.There was little difference between source and sink leaf tissue in the kinetic parameters K(j) and J(max) (30) for uptake of exogenous sucrose supplied via free space. The concentration of solutes in sieve elements and companion cells of the sink leaf was highest in the mature tip area and gradually decreased in the direction of the immature base. There appeared to be no dramatic structural transformation within the phloem of the minor veins that was closely correlated with the time when phloem loading or export began. Rather, there appeared to be a gradual differentiation of phloem which resulted in a sizable proportion of the population of minor vein sieve elements and companion cells attaining maturity in the older sink regions prior to initiation of phloem loading. The area of the leaf undergoing development appeared to exhibit the beginnings of phloem loading 30 to 45 hours prior to onset of export. Import continued into the area in transition until the full level of vein loading was attained. Structural maturation of the phloem and onset of phloem loading are felt to be more preparatory in nature rather than immediately causal events which triggered export.The initiation of export out of a developing leaf, we believe, is the result of the increasing solute content within the sieve element and companion cells of the minor veins, in particular. The higher osmotic pressure in the sieve tubes causes a reversal of the previously inward directed gradient and produces a mass flow, through unobstructed sieve elements, out of the new source region of the leaf.

Evaporite-Carbonate Rocks of the Jurassic Lovelock Formation, West Humboldt Range, Nevada

The Lovelock Formation is an assembly of late Early Jurassic or Middle Jurassic carbonate rocks and gypsum that constitute the youngest preserved sediments and, probably, the last marine deposits in successions of Jurassic rocks in the Carson Sink region of western Nevada. The formation records a set of transitional environments between open marine basinal conditions and an emergent tectonically active terrain. The current extent of the formation is probably a small fraction of its original distribution in the Carson region and, perhaps, in areas of Nevada farther west. The Lovelock Formation occurs only in a pair of nappes in the nappe pile of the northern West Humboldt Range. Geometric relations between intranappe and internappe folds suggest that nappe emplacement and folding were coupled deformations in major Middle Jurassic tectonism. Sites of deposition of the Lovelock Formation were probably not more than a few kilometers east or west of current exposures of the formation. The formation is comprised of three members in a maximum thickness of about 200 m. The lowest is a micrite which underwent emergence and fresh-water diagenesis before deposition of fragmental limestones of the middle member. Conglomerate of the middle member consists exclusively of intraclastic micrite pebbles from the lower member. Finer grained sedimentary breccia above the conglomerate is an accumulation of intraclasts and allochthonous particles from a variety of subenvironments on a carbonate bank. The upper member comprises gypsum and calcarenite, deposited at least in part in standing water of a barred basin. The sequence of motions of the sediment surface relative to sea level recorded in the deposits of the Lovelock Formation is conceivably due to eustatic variations, but the general temporal proximity of deposition of the formation to major tectonism suggests that such motions were probably tectonic. Postdepositional hydrothermal recrystallization occurs sporadically in carbonate rocks of the Lovelock Formation. Such metamorphism was perhaps synchronous with local generation of solution breccias in the upper member and local calcitization of sulfate.

Water table fluctuations under forest and pasture in a karstic region of Southern Australia

Water table heights relative to sea level were measured at monthly or two-monthly intervals during 1963–1965 in shallow observation bore-holes in an area of about 500 km 2 near Nangwarry (37°S, 141°E), South Australia. Part of the area was under improved pasture and part was under plantation forest ( Pinus radiata). The intention was to see if the plant cover affected the ground water recharge. The interpretation of the results was complicated by the presence of an unexpected sink region through which water discharges from the upper limestone aquifer into a lower aquifer. Simplified mathematical models were compared with the observed amplitude and phase of the water table fluctuation and it was concluded that some recharge occurs beneath forest as well as grassland. Statistical analyses of the observations show a very significant dependence upon depth to water for forest sites as well as pasture sites which indicates recharge beneath both kinds of plant cover. It is suggested that recharge beneath forest was less than half of that below pasture.

Effect of Sink Region Anoxia on Translocation Rate

Translocation rate, ATP level, and CO(2) production of a developing leaf (sink leaf) were studied in sugar beet (Beta vulgaris) plants prior to and during anaerobic treatment of the sink leaf. Within 3 to 5 minutes after onset of treatment with a N(2) atmosphere, translocation into the sink leaf decreased to near zero and then recovered to a level of about 50% of the control over the next 2 hours. A decline in CO(2) output and ATP levels coincided with the attainment of the new translocation rate. All three quantities returned to near control levels within 60 to 120 minutes after the sink leaf was returned to air. Swelling and ultrastructural changes in mitochondria coincided with the observed ATP level changes during inhibition and recovery periods. The first phase of marked inhibition of translocation did not coincide with low ATP level and appeared to be caused by decreased membrane permeability during the transition to anaerobic metabolism, possibly as a result of a temporary build up of toxic products. The correlation between ATP level and translocation rate suggests that ATP-dependent active transport in the sink leaf augments the driving force for translocation.

Satellite Observations of the Earth's Radiation Budget

Meteorological satellites have provided the first complete data on energy exchange between earth and space. The planetary albedo is 29 percent for the mean annual case, and the entire earth-atmosphere system is in near radiative equilibrium. More energy is absorbed in tropical regions than previously believed, and major energy source and sink regions exist within latitude belts.

Radioautographic Study of Translocation in Bean Leaves

The movement of the radioactivity from sucrose, indole-3-acetic acid (IAA) and phosphate has been examined in excised bean leaves. Preferential translocation of the labelled materials toward the base of leaf and petiole was demonstrated, suggesting a natural mobilization gradient down the leaf and petiole. Establishment of other mobilization centers in the leaf by local application of N6-benzyladenine diverted the movement of the sucrose label and, to a lesser extent, the phosphate label. There was no apparent mobilization of IAA by benzyladenine. Evidence is provided that there is a continuity of label from the source to the sink regions, and it is suggested that reported instances of noncontinuity of label may be attributable to the refixation of respired C14O2 by tissue treated with benzyladenine. The observations appear to substantiate the concept that the unloading of solutes from the phloem can regulate the direction and intensity of translocation.

RADIOAUTOGRAPHIC STUDY OF TRANSLOCATION IN BEAN LEAVES

The movement of the radioactivity from sucrose, indole‐3‐acetic acid (IAA) and phosphate has been examined in excised bean leaves. Preferential translocation of the labelled materials toward the base of leaf and petiole was demonstrated, suggesting a natural mobilization gradient down the leaf and petiole. Establishment of other mobilization centers in the leaf by local application of N6‐benzyladenine diverted the movement of the sucrose label and, to a lesser extent, the phosphate label. There was no apparent mobilization of IAA by benzyladenine. Evidence is provided that there is a continuity of label from the source to the sink regions, and it is suggested that reported instances of noncontinuity of label may be attributable to the refixation of respired C14O2 by tissue treated with benzyladenine. The observations appear to substantiate the concept that the unloading of solutes from the phloem can regulate the direction and intensity of translocation.

Determination of Electron Density in Magneto-Plasma with Electrostatic Probe

The effects of magnetic field, pressure and discharge current on the saturation electron current flowing in a cylindrical probe are investigated by use of two methods: one is based on the probe characteristic of ion current and the other on the microwave measurement. Experiments are made in helium at pressures ranging from 0.3 to 1.6 mmHg with 10 11 ∼10 12 cm -3 of plasma electron density and 0∼5000 gauss of magnetic field strength. Results of experiments show that the thickness of sink region around the probe perpendicular to the magnetic field is given by V e /(ω p 2 +ω B 2 ) 1/2 where V e is the thermal velocity of electron, and ω p and ω B are the angular frequencies of electron plasma and cyclotron, respectively. Use of this region and the theory developed by Dote enables us to determine the numerical value of the electron density of magneto-plasma. The result obtained by using electron current characteristic of the probe with its axis parallel to the magnetic flux agrees well with the real density. The measurement on the probe perpendicular to the magnetic lines of force is also carried out.

Effect of Sink Region Cooling on Translocation of Photosynthate

The effect of metabolic inhibition of the sink tissues on translocation of (14)C-labeled photosynthate was studied by cooling part or all of the sink region in a translocating sugar beet plant (Beta vulgaris L. var Klein Wanzleben).When the sink region was cooled, 4 phases were observed: a temporary decline, a period of translocation at the pre-treatment rate, a period of decline, and a new steady rate at 35 to 45% of the original rate. The new rate persisted throughout 26 hours of cooling.Cooling half the blade of a developing leaf caused a decline in translocation to the uncooled half. When a portion of the beet was cooled, translocation to a developing leaf located above the supply leaf node increased 30%.Translocation into the treated region recovered rapidly and completely when cooling ceased indicating that cooling had not caused serious damage to tissues. Enhancement of the proportion of (14)C as sucrose in the cooled portion of the sink leaf as compared with the corresponding warm side indicated that sucrose is the chief species of translocate molecule arriving in the sink.The data suggest that the translocation process includes active uptake into storage and growing areas.

Probe Measurement of Electron Density in Magnetized Plasma

Electrostatic probe measurement of electron density in magnetized plasma is discussed. Experiments are made in helium at pressures ranging from 0.3 to 1.6mmHg with 1011-1012/cc of plasma electron density and 0-5000 gauss of magnetic field strength.The influence of magnetic field, pressure and discharge current on the saturation electron current to cylindrical probe is investigated, for which the plasma electron density determined by the following two methods is taken as the true density : one is based on probe characteristic of ion current almost free from the effect of magnetic field, the other is with a microwave cavity devised to become free from the effect of magnetic field. Results of experiment show that the thickness of sink region around the probe perpendicular to the magnetic field is given by Ve/ (ω2p+ω2B) 1/2where Ve is the thermal velocity of electron, and ωP and ωB are respectively the angular frequencies of electron plasma and cyclotron.Use of this region and the theory developed by Dote enables the numerical determination of electron density of magnetized plasma. The electron density calculated by using electron current characteristics of the probe with its axis parallel to the magnetic flux agrees well with the true electron density of magnetized plasma. The electron density measurement with the probe perpendicular to the magnetic line of force is also investigated.

Is Thelypteris reducta Small a Valid Species?

After careful and intensive study of the two species, Thelypteris reducta Small and T. dentata (Forsk.) St. John, I have come to the inescapable conclusion that they are one and the same species. Early in 1939, a friend, returning from a trip to Brazil, brought me a few fern specimens for my herbarium, which she had collected near Rio de Janeiro. There were three or four entire, small plants with good roots, which appeared still to have some life and as they had been out of the ground only about a week, I set them in a pan of water over night, then potted and set them out in the greenhouse. Only one survived, which turned out to be Thelypteris dentata. In the winter of 1941-42, I made several trips down into the lime sink region between Gainesville and Ocala, where I collected a few small plants of T. dentata, and I also collected another one which I found growing within the city limits of Jacksonville; all of these I brought home and planted in my fern garden. About mid-spring of 1942, I took the Brazilian plant, which had grown considerably, out of the greenhouse and planted it in the garden, but in a place entirely apart from the Florida plants of T. dentata, so that I would not confuse them and could observe any differences. Several weeks later I noticed that the Brazilian plant was producing sporophylls so entirely different from any of the previous ones and from those of the native plants of T. dentata, that I took a sporophyll off of the Brazilian plant and from one of the Florida plants and sent them to Dr. Maxon with the query, Are these the same species?' Dr. Maxon replied that they were both Dryopteris dentata (Forsk.) C. Chr., as with his habitual 107

On the Dynamics of the General Atmospheric Circulation

The annual flow of angular momentum across latitudes 30-35� effected by north and south currents lying side by side (cyclonic and anticyclonic " eddies ") appears insufficient to balance the angular momentum generated at the surface in lower latitudes. The discrepancy suggests that there must be also a mean poleward drift of air at upper tropospheric and lower stratospheric levels across the latitudes of the mean surface high pressure belt, with a counterdrift which occurs at least in part in near-surface levels. A variety of auxiliary evidence supports the existence of these flows, which are indicated as intermittent or fluctuating components with mean speed over a long period of the order of a few miles per hour and so, at upper levels, only on the margin of direct observation. The origin of the poleward component is associated with the strong anticyclonic shear to equatorward of the jet stream axis. Since these drifts are found in latitudes where the vertical wind shear is greatest, - they constitute an important agency in the transport of angular momentum from its source region in the tropics to the sink region of higher latitudes. This significant contribution is masked in studies of interchange which invoke the assumption of geostrophic wind. The " index " representing the total strength of the tropical easterly surface winds, which fluctuates considerably, relates closely to the rate of generation of angular momentum in the tropics. On the basis of the drifts referred to above, a descriptive theory of the index cycle is developed, which links the fluctuations of index with the fluctuations in strength and in latitude of the jet stream. Quantitative checks are applied to this theory wherever possible and no discrepancy appears, while the normal sequence of synoptic events agrees broadly with that ascribed to the mutual interactions of surface wind strength, jet-stream, and drift.