bluuebunny/crossref_metadata_2025 huggingface dataset:
The Southern Mountains Zone, Isle of Rum, Scotland: volcanic and sedimentary processes upon an uplifted and subsided magma chamber roof
Authors: HOLOHAN E. P. , TROLL V. R. , ERRINGTON M. , DONALDSON C. H. , NICOLL G. R. , EMELEUS C. H.
Published: March 2009

The Southern Mountains Zone of the Rum Central Complex lies inside a major ring fault and comprises an intricate association of country-rock outcrops, breccias and rhyodacite. The breccias and rhyodacite were long thought to be products of subterranean explosion and intrusion, respectively. Here, we report new observations that support re-interpretation of these units as mass movement deposits and ignimbrites. The most abundant breccias (Coire Dubh-type) consist mainly of country-rock clasts <1 m in diameter in a sand or silt matrix. Internally bedded and graded, and interlayered with sandstones and lithic tuffs, these breccias are interpreted as debris flow and stream flow deposits. Rhyodacite sheets show gradational or sharp, concordant contacts with Coire Dubh-type breccias, and display graded basal lithic tuffs and graded fiamme swarms. These sheets are interpreted as moderately to densely welded rhyodacite ignimbrites (25–100 m thick). A steep body of fragmented (fiamme-bearing) rhyodacite with intrusive non-fragmented contacts is interpreted as an ignimbrite vent system. The rhyodacite and breccia succession is over 200 m thick and unconformably overlies a structurally uplifted Precambrian basement, within which there is also evidence of later subsidence. Outcrops of potential caldera-collapse ‘megabreccia’ are more structurally consistent than previously thought, and are re-interpreted here as coherent segments of Precambrian country rock (caldera floor). The Southern Mountains Zone breccias and rhyodacites respectively reflect sedimentary and pyroclastic processes acting in response to a complex tectonic interplay of intrusion-related uplift and caldera subsidence.
Introduction: from the British Tertiary into the future – modern perspectives on the British Palaeogene and North Atlantic Igneous provinces
Authors: JERRAM DOUGAL A. , GOODENOUGH KATHRYN M. , TROLL VALENTIN R.
Published: March 2009

The study of volcanic rocks and igneous centres has long been a classic part of geological research. Despite the lack of active volcanism, the British Isles have been a key centre for the study of igneous rocks ever since ancient lava flows and excavated igneous centres were recognized there in the 18th century (Hutton, 1788). This led to some of the earliest detailed studies of petrology. The starting point for many of these studies was the British Palaeogene Igneous Province (BPIP; formerly known as the ‘British Tertiary’ (Judd, 1889), and still recognized by this name by many geologists around the globe). This collection of lavas, volcanic centres and sill/dyke swarms covers much of the west of Scotland and the Antrim plateau of Northern Ireland, and together with similar rocks in the Faroe Islands, Iceland and Greenland forms a world-class Large Igneous Province. This North Atlantic Igneous Province (NAIP) began to form through continental rifting above a mantle plume at c. 60 Ma, and subsequently evolved as North America separated from Europe, creating the North Atlantic Ocean.
Studies in Protein Hydrolysis
Authors: Foreman F. W.
Published: March 2009

In the following pages the author gives a preliminary account of his attempts to improve the methods commonly in use for the separation of the products of the hydrolysis of proteins.
The estimation of carbohydrates. V. The supposed precipitation of reducing sugars by basic lead acetate
Authors: Davis William A.
Published: March 2009

Gill in 1871 first pointed out that when an excess of basic lead acetate is added to a solution of invert sugar the negative rotation of the latter is greatly reduced owing to the formation of a soluble lead compound of laevulose. If sufficient lead solution is added the negative rotation may become a positive one; thus in one experiment quoted by Gill a negative reading of – 28° was transformed into a positive value of + 57°. The change of rotation was not, however, permanent and on removing the lead or on acidifying the solution the original rotatory power was restored. The change of rotation was attributed to an effect of the lead on the laevulose only; a solution of dextrose was practically unaffected by the presence of basic lead acetate. Since Gill's paper the effect of basic lead acetate as a source of error in sugar analysis has been the subject of numerous papers especially by Pellet, Svoboda, Edson, Prinsen Geerligs, Watts and Tempany and Eynon.
A preliminary investigation into the occurrence of different kinds of carbonates in certain soils
Authors: Hardy F.
Published: March 2009

1. A sample of marine silt taken from the foreshore of the N.W. coastal belt of the Wash was found as the result of a mineralogical examination to contain dolomite in its mineral assemblage.

2. It was surmised from this discovery that should dolomite be a normal constituent of soils derived from marine silts, its presence might modify in them certain processes such as nitrification in which the neutralising effect of a quick acting base is an essential factor.

3. This supposition was strengthened by certain culture experiments on nitrification, and was to some extent established as a fact by a detailed chemical investigation into the nature of the carbonate content of several soils of known geological and agricultural history.
Basic slags and mineral phosphates
Authors: Vanstone Ernest
Published: March 2009

(1) The relationship between phosphate soluble in 2 per cent, citric acid and total phosphate present has been investigated in the following cases:

(a) Phosphates of known composition.

(b) Basic Slags.

(c) Mineral Phosphates.

(2) The relationship is best shown graphically and in nearly all the above cases is a straight line passing through the origin.

For each of three basic slags of widely differing citric solubility, the graphis a straight line showing that citric solubility is a definite constant, independent of the weight taken in the test, when allowance is made for a small constant error in the determination.

(3) The ratio soluble phosphate/total phosphate in the case of the mineral phosphates Gafsa, Ephos, Nauru, and a West Indian phosphate, depends on the weight taken in the test, the graphs are not straight lines.
Modern methods for experiments with fertilizers and manures
Authors: Sebelien John
Published: March 2009

Even an amateur in agricultural science will admit that nowadays the fertilising effect of a substance cannot be tested merely by adding the substance to the soil and inspecting the resulting crop. This is not an experiment, it may give rise to an observation, but not to a conclusion. The production of the crop is connected with the fertilising process as a post hoc, not as a propter hoc.
A note on the sheraqi soils of Egypt. A study in partial sterilisation
Authors: Prescott James Arthur
Published: March 2009

In a previous communication attention was called to the possibilities of partial sterilisation under field conditions in the case of the summer fallow of Egyptian agriculture.

This fallow period or “sheraqi” is particularly characteristic of the basin system of agriculture during the interval between the harvest of the winter crop and the Nile flood, but it is also common under perennial. conditions of irrigation after the winter crops.
The Electrical Conductivity of Aqueous Soil Suspensions as a Measure of Soil Fertility
Authors: Sen Ashutosh , Wright C. H.
Published: March 2009

Measurements have been made of the electrical conductivity of aqueous suspensions of stored soil samples taken at intervals of several years from four of the Rothamsted classical plots bearing the same crop every year. The results show that under continuous cropping:

1. The initial conductivity (and therefore the soluble salt content) of an unmanured soil decreases steadily to a minimum value, which then remains fairly constant over a long period of years. There is reason to believe that, under the same conditions, the normal initial conductivity of a continuously manured plot (excluding the temporary increased measurements due to application of manure) decreases similarly to a fairly constant minimum value, which is slightly greater than that of an adjacent unmanured soil depending on the kind and probably on the quantity of manure applied.

2. The 7 days’ increase of both unmanured and manured soil decreases progressively. In the case of an unmanured soil for which earlier samples were available, the 7 days’ increase is found to decrease comparatively rapidly during the first few years of continuous cropping.
Investigations in crop husbandry. II. On the age of seed beans
Authors: Garner F. H. , Sandees H. G.
Published: March 2009

1. New and old seed beans have been compared for three years, in the last two of which precise field experiments have been conducted with two different strains.

2. In general new seed gave higher yields than old seed, but the difference was only of the order of 10 per cent. There was some evidence that conditions when the seed was harvested might be more important than age.

3. New seed produced more branches in early spring, and a greater number of pod-bearing stems at harvest; on the other hand, old seed produced stems that were more thickly podded at harvest, and pods that contained a greater number of beans.

4. In one case abnormally large seed produced very vigorous plants, and very large beans at harvest.
The Influence of Rainfall on the Yield of Mangolds at Rothamsted
Authors: Kalamkar R. J.
Published: March 2009

1. The influence of rainfall on the yield of mangolds is studied in this paper.

2. Analysis shows that the variation in the yield due to annual causes cannot be accounted for by a single weather element, rain.

3. An additional inch of rain above the normal, during the period extending from the middle of March to about the end of May, is harmful possibly because of the difficulty in securing a proper tilth and delay in sowing, which results in a shortening of the growing period.
Metabolizable energy values for broiler chicks of eleven samples of field beans (Viciafaba L.) harvested in 1968
Authors: Edwards D. G. , Duthie I. F.
Published: March 2009

The metabolizable energy values of eleven samples of field beans (Throws M.S.). representative of different generations, locations and soil types, were determined using 3-week-old broiler chicks. A mean ‘classical’ value of 2·40 ± 0·09 kcal/g (10·09 kJ/g) was obtained, together with a mean nitrogen-corrected value of 226 ± 0·11 kcal/g (9·47 kJ/g). There was a considerable variation within groups of samples classified according to generation, location or soil type, so that no distinct relationships were detectable. Supplementary analytical data relating to moisture, crude protein, oil and fibre of the samples are also presented.
Dispersion of surface-applied salts in porous media
Authors: Rose D. A.
Published: March 2009

Exact equations to predict the leached fraction of fertilizer applied at the soil surface with irrigation water have been derived from solutions of the equation of hydrodynamic dispersion. These exact equations are compared with an approximate equation derived by Pandey (1979) for the same problem; his equation sometimes gives rise to considerable errors.
Some factors influencing the development of sunflower (Helianthus annuus L.) under dry-farming systems in Sudan
Authors: Khalifa F. M.
Published: March 2009

An experiment was carried out over a 3-year period at two locations in the central rainlands of Sudan under rainfed conditions at one site and under supplementary irrigation at the other to study the effects of cultivars and cultural practices on growth and grain yield of sunflower. Four cultivars, namely, Manohurian, Peredovik, Hungarian-A and Hungarian-B and four intra-row spacings of 15, 30, 45 and 60 cm (in rows 60 cm apart) were tested with three sowing dates starting on 15 July and following at 15-day intervals. Manchurian outyielded the other three varieties under supplementary irrigation whereas under rainfed conditions the reverse was true. This was attributed to the relative earliness in flowering of the varieties and their moisture requirements. Manchurian was the tallest with the thickest stem and a larger head at both locations compared with the other three varieties. Under rainfed conditions, the early sowing date of 15 July gave a significantly higher grain yield than the other two sowing dates, with the last sowing date of 15 August giving significantly least. This is attributed to decreasing moisture availability with delayed sowings. But under supplementary irrigation the effect of sowing date was less marked. Contrasting effects of sowing dates on plant height and stem circumference were obtained under the two systems of production. Under rainfed conditions there was a decrease in plant height and stem circumference with delayed sowing, whereas under supplementary irrigation the reverse was true. A contrasting response of plant height to spacing was also obtained; wider intra-row spacing was associated with taller plants under rainfed conditions and shorter plants under supplementary irrigation. Wider spacing was associated with thicker stems and larger heads at both locations. On the evidence obtained, 45 cm intra-row spacing is recommended for rainfed planting and 30 cm intra-row spacing for irrigated production of sunflower.
The influence of plants on the mineralization of nitrogen and the maintenance of organic matter in the soil
Authors: Theron J. J.
Published: March 2009

The influence of growing plants on nitrification in the soil was studied by means of small lysimeters of which four were planted to a perennial grass, four to an annual millet crop and four were left fallow.

Nitrification was entirely repressed under the grass from the second season after its establishment onwards, and did not take place even when the grass was dormant in winter. This was due to a direct influence of the living root, since in the fallow soil which was treated similarly, nitrification took place freely throughout the winter. Under the annual crop a repression of nitrification could be detected only towards maturity of the crop and the soil solution was completely depleted of nitrates at this period. Nitrification was resumed, however, immediately after the crop was ripe and had died off and continued through the winter.

During the period that nitrification was depressed replaceable ammonia made its appearance in the soil in more than normal quantities. This fact is hold to indicate that the plant exerts its influence on the mineralization of nitrogen in the soil by paralysing the autotrophic dehydrogenase system of the nitrifying organisms without interfering with the process of ammonification and not, as has been claimed, by excreting such quantities of carbonaceous matter that nitrates are reassimilated by micro-organisms.

By virtue of the constancy of the carbon-nitrogen ratio in soils this influence of plants on the mineralization of nitrogen has a very important bearing on the conservation of soil humus and consequently on any system of alternate husbandry. Some of its implications were discussed with particular reference to local fertilizer practice and field experience.
Studies on Calcium Cyanamide. III. Storage and Mixing with Superphosphate
Authors: Richardson H. L.
Published: March 2009

1. On storage under good farm conditions Calcium Cyanamide gained steadily in weight, the increase reaching about 10 per cent. after 27 months. The percentage of nitrogen decreased at a practically equivalent rate, so that there was little change in total nitrogen. The form of the nitrogen remained practically unchanged for the first 6 months; by 12 months there was a slight reduction in cyanamide nitrogen and a slight production of dicyanodiamide—less than 1 per cent. of the total nitrogen.

2. In a farm mixture of Calcium Cyanamide and superphosphate (1:3) cooled by spreading in a thin layer after mixing, 16 per cent, of the nitrogen was converted to dicyanodiamide in the fresh mixture and this increased to 25 per cent, after 1 month's storage. More dicyanodiamide was produced in a series of laboratory mixtures of Calcium Cyanamide and superphosphate, in which heating was allowed to take place. Dicyanodiamide production varied regularly with the composition of the mixtures, rising to a maximum of 50 per cent. of the total nitrogen in the mixture containing 20 per cent. of Calcium Cyanamide, and falling to below 20 per cent. of the nitrogen in the 50 per cent. mixture.
The fat stock of Anglesey and Caernarvon
Authors: Phillips R.
Published: March 2009

1. A survey of the trade in fat cattle, calves and sheep through the collecting centres of the Ministry of Food has been made for the counties of Anglesey and Caernarvon.

2. The results show that the Anglesey stock are invariably heavier and in better condition and marketed slightly earlier in the year, than those of Caernarvon.

3. The imported fat cattle were heavier and more uniform than the home-bred.

4. A check has been made of the variations in live-weight of fat cattle according to colour. Invariably the Black cattle (Welsh) have been lighter, and the Red/White (Hereford) heavier than the average live weight of all cattle of both sexes.

5. The bulk of the meat produced in the two counties is delivered during the autumn months, confirming the experience that the winter fattening of cattle is not now widely practised.

6. In sheep husbandry the two counties are complementary. The small draft mountain ewe, crossed with a heavier type ram, is capable of rearing a fat lamb practically equal to her own body weight in less than 6 months.

7. Losses in mature ewes and rams are suspected to be high because of the small proportions of them, in relation to the population figures, that are delivered to the collecting centres.
A theory for fertilizer response
Authors: Greenwood D. J. , Wood J. T. , Cleaver T. J. , Hunt J.
Published: March 2009

A model is derived that relates yield to levels of applied fertilizer in terms of parameters that have direct physical meaning. N8, P8, and K8 define the contribution of the soil to the supply of nitrogen, phosphorus and potassium for plant growth; BN, BP and BK define the responses to nitrogen, phosphorus and potassium fertilizer at low nutrient levels and aN is the level of nitrogen required to raise the osmotic pressure sufficiently to prevent growth.

To test the model, field experiments were carried out on French beans and summer cabbage in which 125 different combinations of levels of nitrogen, phosphate and potassium fertilizers were applied. The yield data from each block of each experiment fitted the model very well. Fitted values differed from block to block but these differences could be attributed to the fact that for each block equally good fits were often obtained with widely differing parameter values. Estimates of N8 were made from chemical analysis of the (NH4 + NO3) — N of soil samples from the field plots, and P8, and K8 from chemical studies of the adsorption of phosphate and potassium on untreated soil. They were in substantial agreement with the average values obtained by the entirely different procedure of fitting the model to the yield data. Also estimated values for BN, BP and BK and aN from other chemical studies were consistent with those obtained by model fitting.

It is concluded that although the theory has limitations it is broadly in accord with the results of the detailed field experiments.
Forage yield and chemical composition of pearl-millet (Pennisetum typhoides) as influenced by exchangeable sodium
Authors: Singh K. N. , Sharma D. K. , Chillar R. K.
Published: March 2009

The effect of exchangeable sodium percentages (ESP) of 86, 61, 43, 33 and 28 on forage yield and chemical composition of four cultivars of pearl-millet (LC-2, LC-5, LC-6 and LC-7) was studied under field conditions during 1981 and 1982. Dry and green forage yields were significantly higher at 28 ESP over other ESP values. Increasing ESP decreased the yield and concentration of Ca, K and P but increased that of Na in the plants. Cultivar LC-5 was found to give the best performance under sodic soil followed by LC-7, LC-6 and LC-2. At an early stage of crop growth (45 days), cv. LC-2 had significantly lower concentrations of Ca, K and P and a higher Na concentration compared with other cultivars.
Some consequences of imposing different continuousgrazing pressures in the spring on tiller demography and leaf growth
Authors: Tallowin J. R. B. , Williams J. H. H. , Kirkham F. W.
Published: March 2009

The effects of different severities of continuous grazing imposed during the spring, followed by a uniform continuous grazing management from mid-summer onwards, were examined in relation to changes in tiller demography and leaf growth of perennial ryegrass (Lolium perenne). Two grazing severities were imposed, based upon maintaining a constant sward height of either 35 mm (severe) or 75 mm (lenient). From 1 June onwards, a uniform grazing pressure with a sward height of 60 mm was imposed.

Differences in the age class structure of the tiller populations developed during the spring between the two grazing treatments, principally through the suppression of daughter tiller development under the more lenient grazing. The demographic differences between the treatments were further increased during the remainder of the grazing season, under the common grazing management, largely because of the greater production of secondary daughter tillers in the sward which had been leniently grazed. The demographic differences between the swards had little effect on net pasture production during the treatment season, with lamina growth rates being virtually unaffected across a wide range of steadystate, continuous-grazing pressures. However, longer-term effects on pasture development, due to the demographic differences between the swards, did appear in the following season; the more severe grazing pressure treatment resulted in earlier inflorescence development in the subsequent season.
Red and far-red light influence carbon partitioning, growth and flowering of bahia grass (Paspalum notatum)
Authors: Marousky F. J. , Blondon F.
Published: March 2009

Bahia grass (Paspalum notatum Flugge) plants were grown in growth chambers at Gif, France, and at Gainesville in Florida, demonstrating that the species is a long-day plant and greatly influenced by light quality during the photosynthetic period. Flowering occurred in all instances when the middle of the dark period was interrupted with red or red + far-red light. With nightly interruptions of farred light, flowering occurred only when a sufficient quantity of far-red was present during the photosynthetic period. Plants grown under short days with nightly interruptions of red, far-red or red + far-red light had less starch accumulation and greater leaf growth and dry weight than plants grown without nightly light interruptions, whatever the light quality during the photosynthetic period. The treatments did not affect the partitioning of assimilates and flowering in the same way.
Convergence rate for the Boltzmann and Landau equations with soft potentials
Authors: Yu Hongjun
Published: March 2009

The Boltzmann and Landau equations are the classical models in statistical physics and plasma physics. We obtain the satisfactory existence of global classical solutions to the Boltzmann and Landau equations with soft potentials in the whole space. The convergence rate to Maxwellians for such solutions is also obtained.
Continuously stratified flow dynamics over a hollow
Authors: Salas‐Monreal David , Valle‐Levinson Arnoldo
Published: March 2009

To study the effects of bathymetric depressions (hollows) on continuously stratified flows, measurements of current velocity and water density profiles were obtained over two hollows in the lower Chesapeake Bay. Measurements showed an acceleration of the middepth flow as it moved toward the deepest part of the hollow, in contrast to the deceleration expected from two‐dimensional Bernoulli‐type dynamics. The acceleration was attributed to lateral water intrusions that were most apparent during floods, as corroborated by observations in a transverse section that crossed the deepest part of one of the hollows. The flow acceleration toward the deepest part of the hollows during flood, favored by lateral water intrusions, was deflected toward the right (looking landward) owing to Coriolis accelerations. In general, during ebb and flood, the dynamics over the hollows could be explained with three‐dimensional Bernoulli‐type dynamics (pressure gradient balanced by advection) modified by Coriolis acceleration. Outside the hollows, the dynamics were between pressure gradient and friction (stress divergence). The transition from frictionally dominated dynamics (outside the hollow) to advection‐dominated dynamics (inside the hollow) appears at the region where the bathymetric slope equals the bottom drag coefficient.
Heterogeneous ice nucleation measurements of secondary organic aerosol generated from ozonolysis of alkenes
Authors: Prenni Anthony J. , Petters Markus D. , Faulhaber Annelise , Carrico Christian M. , Ziemann Paul J. , Kreidenweis Sonia M. , DeMott Paul J.
Published: March 2009

Ice nuclei (IN) are those particles which catalyze ice nucleation in the atmosphere. Ambient measurements suggest that the main particle types that function as IN are metal oxides and dust. However, carbonaceous particles often are the next most abundant IN particle type, although the source and exact chemical compositions of these particles are unknown. Here we explore the ice nucleating ability of one potential source of carbonaceous IN to the atmosphere, secondary organic aerosol (SOA). We generated SOA by ozonolysis of 25 different organic precursors in the presence of an OH scavenger. For all experiments, ice nucleation was not observed in detectable quantities. We conclude that SOA generated from ozonolysis of alkenes is an unlikely source of IN to the atmosphere.
Limitations of Preisach Theory: Elastic aftereffect, congruence, and end point memory
Authors: Claytor K. E. , Koby J. R. , TenCate J. A.
Published: March 2009

The earliest reported observations of hysteresis in rocks were published at the beginning of the last century. In analogy with magnetic systems, a Preisach model was adapted in the early 1980s and used to describe the elastic hysteresis in rocks. In spite of its apparent success, as with any model of a physical process, use of the Preisach model has limitations that need to be carefully considered. Several new stress‐strain measurements on various sedimentary rocks are reported here to probe the limits of the Preisach model. “Quasistatic” stress‐strain measurements shown here explore in detail some of the predictions of this model, namely end point memory and congruence but also demonstrate the impact of elastic aftereffect (or relaxation). It was found, for example, that at certain stress‐strain measurement rates for Berea sandstone, elastic after‐effect/relaxation effects dominate, hysteresis loops completely vanish, the Preisach model fails, and simple nonlinear behavior remains.
Response of the magnetosphere‐ionosphere system to a sudden southward turning of interplanetary magnetic field
Authors: Yu Yiqun , Ridley Aaron J.
Published: March 2009

A sudden southward turning of interplanetary magnetic field (IMF) is simulated by the University of Michigan's BATS‐R‐US model. The main goal of this study is to determine the time delay as well as physical processes between when an IMF discontinuity reaches the bow shock, when reconnection is initiated at the magnetopause, and when the ionosphere starts to react. While observations or empirical models might give an estimate of the time delay for the propagation of the discontinuity from the bow shock to the magnetopause, the global MHD simulation provides a more comprehensive insight of responses of the magnetosphere‐ionosphere system. An idealized north‐to‐south IMF transition is modeled, using a solar wind velocity of 400 km/s. After the southward IMF encounters the bow shock, it takes about 6 min for the north‐to‐south IMF transition front to arrive at the subsolar geomagnetic field. The ionospheric response to this sudden southward IMF turning is delayed by another ∼4 min, during which the magnetosphere undergoes a conversion from cusp reconnection to subsolar reconnection and the Alfvén wave propagation to the ionosphere takes place. Thereafter, changes in the ionosphere and ground magnetic perturbations associated with the southward IMF are observed. These responses appear to be globally onset as described in many other studies. The time it takes from the encounter of the IMF transition with the bow shock to when the ionospheric reaction takes place varies with the solar wind speed, ranging from nearly 15 min for a solar wind speed of 300 km/s to just over 6 min for solar wind speeds of 600 km/s.
Auroral arc and oval electrodynamics in the Harang region
Authors: Marghitu O. , Karlsson T. , Klecker B. , Haerendel G. , McFadden J.
Published: March 2009

Auroral arcs are typically described in terms of an upward field‐aligned current (FAC) sheet above the arc, connected by ionospheric Pedersen current to a downward FAC sheet near the arc. On the basis of data measured by the FAST spacecraft, conjugate with ground optical observations, we present first a wide and stable winter evening arc, where this standard model does not apply. The arc is observed in the Harang region during the growth phase of a modest substorm, poleward of the convection reversal (CR) boundary. Although the magnetic field data suggest the typical configuration, the two FAC sheets appear to be decoupled near the satellite footprint: the upward FAC is fed by the westward electrojet (WEJ), while the downward FAC feeds the eastward electrojet (EEJ). The examination of the arc by the newly developed ALADYN technique confirms this peculiar current topology. For comparison, we apply ALADYN also to a second evening arc, located within the Harang region equatorward from the CR. The arc is confirmed to have the standard configuration, consistent with a former study, but substantial FAC‐EJ coupling is inferred in the auroral oval both poleward and equatorward of the arc. A key element for the topology of the current closure is the westward component of the electric field, which influences the relative location of the CR with respect to the large‐scale FAC reversal (FR) boundary. As proved by tests on synthetic data, a westward component of the electric field pushes the CR toward the FR, preventing thus the standard FAC closure, while the conductance and FAC pattern shape the CR profile. Since a westward electric field is often measured in the Harang region, the FAC‐EJ coupling is expected to be an essential ingredient there. This has important implications for the current closure in the equatorial magnetosphere and for the auroral current circuit in the WEJ region, closely related to the substorm process.
Assessment of sprite initiating electric fields and quenching altitude of a1Πg state of N2 using sprite streamer modeling and ISUAL spectrophotometric measurements
Authors: Liu Ningyu , Pasko Victor P. , Frey Harald U. , Mende Stephen B. , Su Han‐Tzong , Chen Alfred B. , Hsu Rue‐Ron , Lee Lou‐Chuang
Published: March 2009

In this study, we compare sprite streamer modeling results with Imager of Sprites and Upper Atmospheric Lightning (ISUAL) spectrophotometric data for several sprite events. The model positive streamers are simulated for two representative magnitudes of the quasi‐electrostatic field produced by cloud‐to‐ground lightning discharges, reflecting conditions at 70 km altitude during the initial stage of sprite formation. The intensity ratio of the second positive band system of N2 (2PN2) to the first negative system of N2+ (1NN2+) is obtained separately from the modeling and the ISUAL measurements. The comparison results indicate that the ratio obtained for the streamer developing in an electric field close to the conventional breakdown threshold field Ek agrees with the ISUAL measurements at the very early stage of the sprite development better than for the streamer developing in a field much lower than Ek. This finding supports the sprite theory proposing that sprites are caused by conventional breakdown of air when the lightning field in the upper atmosphere exceeds the local breakdown threshold field, which has also been supported by a recent study by Hu et al. (2007) comparing modeled lightning fields obtained using measured current moments of causative lightning discharges and video observations of sprites. The fact that the early stage emissions from the sprites under study are well explained by the radiation from streamers in strong fields allows the use of ISUAL data to gain additional information on the poorly known quenching altitude of the N2(a1Πg) state, which is responsible for N2 Lyman‐Birge‐Hopfield band system. The results confirm that the 77 km suggested in previous study by Liu and Pasko (2005) is a good estimate for the quenching altitude of N2(a1Πg).
Constraints on the active tectonics of the Friuli/NW Slovenia area from CGPS measurements and three‐dimensional kinematic modeling
Authors: Bechtold M. , Battaglia M. , Tanner D. C. , Zuliani D.
Published: March 2009

We use site velocities from continuous GPS (CGPS) observations and kinematic modeling to investigate the active tectonics of the Friuli/NW Slovenia area. Data from 42 CGPS stations around the Adriatic indicate an oblique collision, with southern Friuli moving NNW toward northern Friuli at the relative speed of 1.6 to 2.2 mm/a. We investigate the active tectonics using 3DMove, a three‐dimensional kinematic model tool. The model consists of one indenter‐shaped fault plane that approximates the Adriatic plate boundary. Using the “fault‐parallel flow” deformation algorithm, we move the hanging wall along the fault plane in the direction indicated by the GPS velocities. The resulting strain field is used for structural interpretation. We identify a pattern of coincident strain maxima and high vorticity that correlates well with groups of hypocenters of major earthquakes (including their aftershocks) and indicates the orientation of secondary, active faults. The pattern reveals structures both parallel and perpendicular to the strike of the primary fault. In the eastern sector, which shows more complex tectonics, these two sets of faults probably form an interacting strike‐slip system.
A statistical approach to the life cycle analysis of cumulus clouds selected in a virtual reality environment
Authors: Heus Thijs , Jonker Harm J. J. , Van den Akker Harry E. A. , Griffith Eric J. , Koutek Michal , Post Frits H.
Published: March 2009

In this study, a new method is developed to investigate the entire life cycle of shallow cumuli in large eddy simulations. Although trained observers have no problem in distinguishing the different life stages of a cloud, this process proves difficult to automate, because cloud‐splitting and cloud‐merging events complicate the distinction between a single system divided in several cloudy parts and two independent systems that collided. Because the human perception is well equipped to capture and to make sense of these time‐dependent three‐dimensional features, a combination of automated constraints and human inspection in a three‐dimensional virtual reality environment is used to select clouds that are exemplary in their behavior throughout their entire life span. Three specific cases (ARM, BOMEX, and BOMEX without large‐scale forcings) are analyzed in this way, and the considerable number of selected clouds warrants reliable statistics of cloud properties conditioned on the phase in their life cycle. The most dominant feature in this statistical life cycle analysis is the pulsating growth that is present throughout the entire lifetime of the cloud, independent of the case and of the large‐scale forcings. The pulses are a self‐sustained phenomenon, driven by a balance between buoyancy and horizontal convergence of dry air. The convective inhibition just above the cloud base plays a crucial role as a barrier for the cloud to overcome in its infancy stage, and as a buffer region later on, ensuring a steady supply of buoyancy into the cloud.
Evidence for carbonyl sulfide (OCS) conversion to CO in the lower atmosphere of Venus
Authors: Yung Yuk L. , Liang M. C. , Jiang X. , Shia R. L. , Lee C. , Bézard B. , Marcq E.
Published: March 2009

The chemical regimes in the atmosphere of Venus vary from photochemistry in the middle atmosphere to thermal equilibrium chemistry in the lower atmosphere and the surface. Many chemical cycles have been proposed, but few details about these cycles are fully verified by comparison between observations and modeling. Recent high‐quality data of carbonyl sulfide (OCS) and CO from ground‐based and Venus Express observations provide a unique opportunity to test our understanding of chemistry and transport in the lower atmosphere of Venus. The spatial distributions of OCS and CO in the atmosphere reflect a sensitive balance between chemistry and transport. On the basis of our updated photochemical model and winds from Lee et al.'s (2007) general circulation model, we study the chemistry and transport in a simplified two‐dimensional chemistry‐transport model. OCS is produced by heterogeneous reactions on the surface; the middle atmosphere is a net sink for OCS. The combination of data and modeling provides strong evidence for the loss of OCS by conversion to CO. The detailed chemical mechanism is currently unknown, although a number of speculations have been proposed. The sensitivity of the distributions of OCS and CO to model parameters is reported.
Atmospheric 10Be in an Antarctic soil: Implications for climate change
Authors: Schiller M. , Dickinson W. , Ditchburn R. G. , Graham I. J. , Zondervan A.
Published: March 2009

Concentrations of 10Be, 9Be, and salt in a soil profile from the lower Wright Valley reveal two distinct climatic regimes. In the upper horizon of the soil profile, a thin gravel lag overlies the Hart ash (3.9 ± 0.3 Ma), and this sits on the surface of a well‐developed paleosol, which makes up the lower horizon of the profile. The surface lag has a smaller inventory of 10Be than predicted from the fallout rate at nearby Taylor Dome. Below the gravel, the Hart ash is virtually devoid of 10Be and the calculated erosion rate for the gravel‐ash horizon is 2.8 m Ma−1. The paleosol, which has been sealed by the overlying ash, has a relatively high inventory of 10Be, and this gives it a significantly lower erosion rate (0.5 m Ma−1) than the gravel‐ash horizon. Beryllium‐10 migrates into a soil profile either by solution transport or by fine‐particle translocation. The lack of 10Be in the Hart ash indicates that neither of these processes have been active at this site for the past 3.9 Ma. However, enrichment of 10Be in the paleosol indicates they were active prior to deposition of the ash. The most likely reason these processes were active is that there was more water, which could translocate fine particles with attached 10Be. Thus, the gravel‐ash horizon developed in climatic conditions similar to the present, while the paleosol developed in wetter and possibly warmer conditions during the early Pliocene and possibly before that time.
Spatial rain correlation analysis for application in site diversity design
Authors: Nagaraja Chethana , Otung Ifiok
Published: March 2009

Analysis of spatial correlation of rainfall rate and of slant path rain attenuation in order to optimize site separation and baseline orientation in site diversity design is presented. For this study, 4 years of rainfall rate measurements were obtained from the Hydrological Radar Experiment dense rain gauge network and associated radar facility in South England. The slant path rain attenuation correlations are analyzed for a hypothetical Earth‐space propagation path at 20 GHz. Results show that the correlation of slant path rain attenuations at two diversity sites reaches a minimum at a separation of about 20 km between the two sites and a baseline orientation of acute angle above 30°.
Potentials of polarimetric SAR interferometry for agriculture monitoring
Authors: Lopez‐Sanchez Juan M. , Ballester‐Berman J. David
Published: March 2009

This paper is aimed to define the main specifications and system requirements of a future spaceborne synthetic aperture radar (SAR) mission with polarimetric and interferometric capabilities, to be applied in agriculture monitoring. Firstly, a previous discussion concerning the applications of remote sensing to agriculture and the requirements demanded by end users is introduced. Then, a review of polarimetric SAR and interferometric SAR techniques employed in agriculture is performed in order to explore and justify the potential contributions to crop parameter retrieval of polarimetric SAR interferometry (PolInSAR). The current status of the research about PolInSAR when applied to the retrieval of biophysical parameters of agricultural crops is also addressed, covering recent advances in theoretical modeling aspects (both direct and inverse models), the validation carried out so far with indoor data, and complementary information provided by other different but related experiments. From this experience, we describe some system specifications that will be important for the success of this technique. Among them it is emphasized the need of baselines larger than usual, medium‐high frequency band, and a mandatory single‐pass mode for overcoming temporal decorrelation. Finally, a set of future experiments is also proposed for additional testing and confirmation of observations made so far regarding minimum baseline requirements, temporal evolution of observables and modeling issues, among others.
Estimating Blood and Brain Concentrations and Blood-to-Brain Influx by Magnetic Resonance Imaging with Step-Down Infusion of Gd-DTPA in Focal Transient Cerebral Ischemia and Confirmation by Quantitative Autoradiography with Gd-[14C]DTPA
Authors: Knight Robert A , Karki Kishor , Ewing James R , Divine George W , Fenstermacher Joseph D , Patlak Clifford S , Nagaraja Tavarekere N
Published: March 2009

An intravenous step-down infusion procedure that maintained a constant gadolinium-diethylene-triaminepentaacetic acid (Gd-DTPA) blood concentration and magnetic resonance imaging (MRI) were used to localize and quantify the blood-brain barrier (BBB) opening in a rat model of transient cerebral ischemia ( n = 7). Blood-to-brain influx rate constant ( K i) values of Gd-DTPA from such regions were estimated using MRI-Patlak plots and compared with the K, values of Gd-[14C]DTPA, determined minutes later in the same rats with an identical step-down infusion, quantitative autoradiography (QAR), and single-time equation. The normalized plasma concentration-time integrals were identical for Gd-DTPA and Gd-[14C]DTPA, indicating that the MRI protocol yielded reliable estimates of plasma Gd-DTPA levels. In six rats with a BBB opening, 14 spatially similar regions of extravascular Gd-DTPA enhancement and Gd-[14C]DTPA leakage, including one very small area, were observed. The terminal tissue-plasma ratios of Gd-[14C]DTPA tended to be slightly higher than those of Gd-DTPA in these regions, but the differences were not significant. The MRI-derived K i, values for Gd-DTPA closely agreed and correlated well with those obtained for Gd-[14C]DTPA. In summary, MRI estimates of Gd-DTPA concentration in the plasma and brain and the influx rate are quantitatively and spatially accurate with step-down infusions.
When Hypothermia Meets Hypotension and Hyperglycemia: The Diverse Effects of Adenosine 5′-Monophosphate on Cerebral Ischemia in Rats
Authors: Zhang Feng , Wang Suping , Luo Yumin , Ji Xunming , Nemoto Edwin M , Chen Jun
Published: March 2009

Mild hypothermia renders potent neuroprotection against acute brain injury. Recent reports show that adenosine 5'-monophosphate (AMP) plays a role in thermoregulation and induces hypothermia in mice. Therefore, this study sought to determine whether AMP induces hypothermia in rats and to study its collective effects on cerebral ischemia induced by 2-h middle cerebral artery occlusion. An intraperitoneal injection of AMP induced hypothermia dose-dependently. At the dose of 4 mmol/kg, AMP induced promising mild hypothermia for 2.5 h. Unexpectedly, the AMP-induced hypothermia failed to reduce infarct volume after brain ischemia; instead, it exaggerated the ischemic damage, indicated by an increased infarct volume, as well as increased incidences of hemorrhagic transformation, seizure, and animal death. Physiologic parameter monitoring revealed that AMP causes profound hypotension, leading to cerebral hypoperfusion. Furthermore, AMP administration resulted in severe hyperglycemia, metabolic acidosis, and hypocalcemia. In addition, western blots showed early dephosphorylation and degradation of AMP-activated kinase in the ischemic cortex in AMP-treated rats. Taken together, our findings suggest that AMP induces hypothermia in rats, probably by limiting cellular access to glucose. However, the potential neuroprotection of AMP-mediated hypothermia against ischemia was overwhelmed by the detrimental effects of hypotension and hyperglycemia, thus making AMP an unlikely agent for inducing hypothermia to protect the brain against ischemic injury.
An information-bearing seed for nucleating algorithmic self-assembly
Authors: Barish Robert D. , Schulman Rebecca , Rothemund Paul W. K. , Winfree Erik
Published: March 2009

Self-assembly creates natural mineral, chemical, and biological structures of great complexity. Often, the same starting materials have the potential to form an infinite variety of distinct structures; information in a seed molecule can determine which form is grown as well as where and when. These phenomena can be exploited to program the growth of complex supramolecular structures, as demonstrated by the algorithmic self-assembly of DNA tiles. However, the lack of effective seeds has limited the reliability and yield of algorithmic crystals. Here, we present a programmable DNA origami seed that can display up to 32 distinct binding sites and demonstrate the use of seeds to nucleate three types of algorithmic crystals. In the simplest case, the starting materials are a set of tiles that can form crystalline ribbons of any width; the seed directs assembly of a chosen width with >90% yield. Increased structural diversity is obtained by using tiles that copy a binary string from layer to layer; the seed specifies the initial string and triggers growth under near-optimal conditions where the bit copying error rate is <0.2%. Increased structural complexity is achieved by using tiles that generate a binary counting pattern; the seed specifies the initial value for the counter. Self-assembly proceeds in a one-pot annealing reaction involving up to 300 DNA strands containing >17 kb of sequence information. In sum, this work demonstrates how DNA origami seeds enable the easy, high-yield, low-error-rate growth of algorithmic crystals as a route toward programmable bottom-up fabrication.
Pupillometric and behavioral markers of a developmental shift in the temporal dynamics of cognitive control
Authors: Chatham Christopher H. , Frank Michael J. , Munakata Yuko
Published: March 2009

The capacity to anticipate and prepare for future events is thought to be critical for cognitive control. Dominant accounts of cognitive control treat the developing system as merely a weaker version of the adult system, progressively strengthening over time. Using the AX Continuous Performance Task (AX-CPT) in combination with high-resolution pupillometry, we find that whereas 8-year-old children resemble adults in their proactive use of cognitive control, 3.5-year-old children exhibit a qualitatively different, reactive form of cognitive control, responding to events only as they unfold and retrieving information from memory as needed in the moment. These results demonstrate the need to reconsider the origins of cognitive control and the basis for children's behaviors across domains.