bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of acoustic full wavetrains for the determination of lithology, reservoir and mechanical parameters of formation1
Authors: Bała Maria , Jarzyna Jadwig A. 
Published: April 2006

AbstractThe significant development in acoustic full waveform logging during the last ten years has made it increasingly possible for log analysts to determine the physical properties of a rock formation in situ.Parallel to the methods applied to a single wavetrain during seismic processing, the new techniques, used for sets of wavetrains, have been successfully tested with acoustic full waveforms. Instantaneous characteristics analysis is included in this group of methods. This approach, leading to qualitative and quantitative interpretation, reveals the influence of small changes in physical properties on acoustic full wavetrains.Applications of complex acoustic waveform analysis for the determination of inhomogeneous zones are presented. Colour diagrams of instantaneous characteristics are used for the detection of fractured regions and slow formations with increased attenuation of acoustic waves.Results of the interpretation of individual acoustic full waveforms, based on cross‐correlation and spectral analysis, using the IDNP and IDNS computer programs, e.g. velocities of compressional waves, shear and Stoneley waves, are presented. Since the bulk density of the rocks was known, it was possible, using the velocities of P‐ and S‐waves obtained, to calculate the dynamic elastic moduli. We used the interpretation of acoustic full wavetrains to calculate porosity. The sonic porosity is compared to the porosity obtained from other logs and to that obtained from core sample analysis.The examples of acoustic full wavetrains were recorded in the Miocene sulphur‐bearing limestones in central Poland. Field measurements were made using the domestic prototype equipment for well log recordings in shallow boreholes.
Habitat type predicts genetic population differentiation in freshwater invertebrates
Authors: MARTEN ANDREAS , BRÄNDLE MARTIN , BRANDL ROLAND 
Published: April 2006

AbstractA basic challenge in evolutionary biology is to establish links between ecology and evolution of species. One important link is the habitat template. It has been hypothesized, that the spatial and temporal settings of a habitat strongly influence the evolution of species dispersal propensity. Here, we evaluate the importance of the habitat type on genetic population differentiation of species using freshwater habitats as a model system. Freshwater habitats are either lentic (standing) or lotic (running). On average, lotic habitats are more stable and predictable over space and time than lentic habitats. Therefore, lentic habitats should favour the evolution of higher dispersal propensity which ensures population survival of lentic species. To test for such a relationship, we used extensive data on species’ genetic population differentiation of lentic and lotic freshwater invertebrates retrieved from published allozyme studies. Overall, we analysed more than 150 species from all over the world. Controlling for several experimental, biological and geographical confounding effects, we always found that lentic invertebrates exhibit, on average, lower genetic population differentiation than lotic species. This pattern was consistent across insects, crustaceans and molluscs. Our results imply fundamental differences in genetic population differentiation among species adapted to either lentic or lotic habitats. We propose that such differences should occur in a number of other habitat types that differ in spatio‐temporal stability. Furthermore, our results highlight the important role of lotic habitats as reservoirs for evolutionary processes and the potential for rapid speciation.
Far-infrared detection limits – II. Probing confusion including source confusion
Authors: Jeong Woong-Seob , Pearson Chris P. , Lee Hyung Mok , Pak Soojong , Nakagawa Takao 
Published: April 2006

Abstract
We present a comprehensive analysis for the determination of the confusion levels for the current and the next generation of far-infrared surveys assuming three different cosmological evolutionary scenarios. We include an extensive model for diffuse emission from infrared cirrus in order to derive absolute sensitivity levels taking into account the source confusion noise due to point sources, the sky confusion noise due to the diffuse emission, and instrumental noise. We use our derived sensitivities to suggest best survey strategies for the current and the future far-infrared space missions Spitzer, AKARI (ASTRO-F), Herschel and SPICA. We discuss whether the theoretical estimates are realistic and the competing necessities of reliability and completeness. We find the best estimator for the representation of the source confusion and produce predictions for the source confusion using far-infrared source count models. From these confusion limits considering both source and sky confusions, we obtain the optimal, confusion limited redshift distribution for each mission. Finally, we predict the cosmic far-infrared background (CFIRB), which includes information about the number and distribution of the contributing sources.
Effect of brief treatments with benzyladenine on growth and development of watermelon cotyledons
Authors: LONGO G. P. , OLGINATI M. , ROSSI G. , VALENTE M. , LONGO C. P. 
Published: April 2006

Abstract Watermelon (Citrullus vulgaris Schrad.) cotyledons were excised from the seed after 24 h of imbibition and incubated for different times (ranging from 1 to 240 min) on filter paper saturated with 0.1 mM BA (benzyladenine) solution. After the incubation in BA the cotyledons were thoroughly rinsed in water and grown for 5 days in darkness on filter paper saturated with distilled water.Continuous presence of BA is not a prerequisite for optimal growth. Several effects of the hormone (stimulation of expansion growth, acceleration of lipid breakdown, enhancement of hydroxypyruvate reductase activity, increase in carotenoid content) are more intensive if the cotyledons are treated with BA for a relatively short time and then grown in water. Maximal effects are observed after a 4 h exposure to BA. A single 1 min exposure is sufficient to elicit measurable effects on growth, hydroxypyruvate reductase and carotenoid content. The sensitivity to very short exposures is considerably different for different hormone effects. Carotenoid content and hydroxypyruvate reductase activity are enhanced much more than expansion growth.
Effect of temperature on ion content, ion fluxes and energy metabolism in Chara corallina
Authors: RAVEN J. A. , SMITH F. A. 
Published: April 2006

Abstract Effects of temperature on the ionic relations and energy metabolism of Chara corallina were investigated. Measurements were made of the ionic content, tracer ion fluxes, and photosynthetic and dark CO2 fixation in isolated cells, and of O2 exchange in photosynthesis and respiration in isolated shoot apices.The total intracellular concentration of K+, Na+ and Cl− was the same in cells held for 5 days in non‐growing medium at 15°C (the growth temperature) as in those held at 25°C or 5°C. The tracer influx in the light of all ions tested (Rb+, Na+, CH3NH3+, Cl− and H2PO4−) was lower at 5°C than at 15°C in experiments in which cells were subjected to 5°C for less than 24 h in toto. The influx at 25°C was greater than that at 15°C for H2PO−4, there was no difference between the two temperatures for Na+, while the influx at 25°C was less than that at 15°C for Cl−, Rb+ and CH3NH3+ For Cl− and H2PO−4 similar results were found in later experiments with cells grown at 20—23°C. Photosynthetic CO2 fixation and O2 evolution, and respiratory O2 uptake, are greater at 25°C, and lower at 5°C, than they are at the growth temperature of 15°C. In longer‐term pretreatments at the different temperatures, tracer Cl− influx at 15°C and particularly at 25°C were lower than in short‐term experiments, while the influx at 5°C was higher.It was concluded from these experiments, and from previous data on H+ free energy differences across the plasmalemma, that (1) the maintenance of internal ion concentrations involves a close balancing of influx and efflux of K+, Na+ and Cl− at all experimental temperatures; (2) the regulation of the tracer fluxes of the ions is kinetic rather than thermodynamic and (3) that the tracer fluxes at low temperatures are not restricted by the rate at which respiration or photosynthesis can supply energy to them.
Chilling injury in plants—the role of membrane lipid fluidity
Authors: WOLFE JOE 
Published: April 2006

Abstract. Many authors have associated chilling injury in plants with changes in the mobility of membrane lipids but have not proposed specific mechanisms for this association.This paper explains how the mobility of membrane lipids can affect membrane thickness, membrane permeability, the electric field, cation concentration and water ordering near a membrane and hence change the conformation (and thus activity) of a membrane‐bound enzyme. The complications in such a model due to protein‐lipid interactions and lateral phase separations are also discussed.
Effects of low temperatures on the loss of innate dormancy and the development of induced dormancy in seeds of Rumex obtusifolius L. and Rumex crispus L.
Authors: TOTTERDELL SUSAN , ROBERTS E. H. 
Published: April 2006

Abstract It is possible to remove the innate dormancy of seeds of Rumex crispus L and Rumex obtusifolius L. by an initial period of low‐temperature stratification, providing the seeds are then transferred to a higher temperature. The lower the initial temperature within the range 1.5°‐15°C, the greater the germination; there is no stratification effect at 20°C. Although 10°C and 15°C were shown to be suitable for both stratification and for the process of germination itself, neither temperature results in any germination if given constantly: a change from a lower to a higher temperature is essential.The optimum period for stratification depends on two separate processes which occur during the treatment–a rapid loss of innate or primary dormancy and a slower development of induced or secondary dormancy. Within the range 1.5°‐15°C the rate of loss of innate dormancy appears to be independent of light and is probably independent of temperature. In contrast, the rate of induction of secondary dormancy increases with increase in temperature, and is more rapid in the dark than the light. The rate of induction of secondary dormancy during stratification is greater in R. crispus than in R. obtusifolius. As a consequence, maximum germination was obtained in both species after stratification at 1.5°C in the light, the optimum period of treatment being about 4 weeks in R. Obtusifolius and 6 weeks in R. crispus, while the maximum germination obtained and the optimal period of stratification decrease in both species with increase in stratification temperature.
Sites of acid phosphatase in the differentiating root protophloem of Nymphoides peltata (S.G. Gmel.) O. Kuntze.
Authors: OPARKA K. J. , JOHNSON R. P. C. , BOWEN I. D. 
Published: April 2006

Abstract Sites of acid‐phosphatase activity were found in the differentiating root protophloem of Nymphoides peltata by lead‐salt and by azo‐dye methods. Different substrates revealed different subcellular locations of the enzyme. The substrates β‐glycerophosphate (β‐GP) and naphthol ASBI phosphate revealed enzyme activity at similar sites within the sieve element. These sites included plasmodesmata, dictyosomes and small vacuoles in the cytoplasm. The substrate p‐nitrophenylphosphate (p‐NPP), however, revealed additional sites of acid‐phosphatase activity which were not detectable by either naphthol ASBI phosphate or β‐GP. For example, the inner region of the wall in mature sieve elements showed conspicuous acid‐phosphatase activity only when p‐NPP was used as substrate. The significance of the different locations of acid phosphatase within the sieve element is discussed.The convoluted ER, characteristic of immature sieve elements of N. peltata, failed to show acid‐phosphatase activity whichever substate was used. By contrast, the stacked ER found in the parietal layer of mature sieve elements showed prominent acid‐phosphatase activity regardless of the substrate used. The demonstration of acid‐phosphatase activity in the stacked ER, and by both lead‐salt and azo‐dye methods, suggests that this organelle is a true site of acid‐phosphatase activity.The onset of acid‐phosphatase activity in the ER in later stages of sieve‐element differentiation is compatible with the view that stacked ER plays a role in the final autolysis of the sieve‐element protoplast.
The effect of salinity on the yield and composition of Diplachne fusca (Kallar grass)
Authors: SANDHU G. R. , ASLAM Z. , SALIM M. , SATTAR A. , QURESHI R. H. , AHMAD N. , WYN JONES R. G. 
Published: April 2006

Abstract. Aspects of the response of Kallar grass (Diplachne fusca) to root salinity have been studied. Field observation on the high level of tolerance of this species have been mirrored in pot trials and a 50% yield (dry matter) was obtained at ECe 22.3. While salt stress led to Na and Cl uptake, most of these ions appeared to be secreted selectively from the leaves. The shoot K+ content on a tissue water basis remained unaffected by salt stress and the shoot tissue had a high K+ selectivity. Osmotic adaptation was mainly brought about by tissue dehydration and not net salt accumulation although the compatible solute glycinebetaine was accumulated in fairly high concentrations.The organic and inorganic chemical composition of the shoots, including the trace elements Zn, Fe, Cu and Mn, is such as to make this species a highly promising plant for the exploitation of saline soils which might otherwise not be amenable to agriculture use.
The effect of CO2on potassium transport byChlorella fusca
Authors: TROMBALLA H. W. 
Published: April 2006

Abstract.The effect of CO2on net K+uptake byChlorella fuscagrown on high CO2levels was examined by passing 1.5% CO2through algal suspensions gassed previously with air or CO2‐free air Addition of CO2in the light caused a large net uptake of K+(initial velocity 4.2–9.2 mmol s−1m−3cells) which decreased the concentration of K+in the supernatant from 0.1–0.2 mol m−3to 3–10 mmol m−3. In the dark and in the presence of 30 mmol m−3DCMU, no effects were found.Measurement or the unidirectional K+fluxes by using86Rb+as a label showed that in the presence of 1.5% CO2, influx of K+was increased by a factor of 2–4 while efflux was inhibited completely.CO2hyperpolarized the membrane potential (determined through TPP+uptake) from –120mV to –130 mV which could not explain the more than 15,000‐fold K+accumulations.In the light, CO2lowered the intracellular pH (determined with DMO) by 0.5 units. In the dark and in the presence of DCMU only, a small acidification of 0.1 units was found.During the first 15 min after addition of CO2the malate content of the cells increased from 0.7 to 1.5 mol m−3packed cells.On the basis of these and earlier results, CO2‐induced net K+uptake is interpreted as a stimulation of an electroneutral ATP‐dependent K+/H+exchange at the plasmalemma. This exchange acts as a ‘pHstat’ by reducing the intracellular acidification caused by production of acidic assimilation products.
Diurnal course of the temperature in aLithopssp. (Mesembryanthemaceae Fenzl) and its surrounding soil
Authors: ELLER BENNO M. , NIPKOW ANDRÉ 
Published: April 2006

Abstract.The embedding ofLithopsplants into the soil could be an adaptation to protect the plants from critical low or high temperatures. Thermoelectric measurements onLithops leslieiN.E. Br andL. turbiniformis(Haw.) N.E. Br. were made to determine whether the temperatures of the plant tissues at various depths differ from those in the soil close to the plant. The environmental conditions of their habitat were simulated in a growth chamber equipped with a cold sky to simulate the net radiation loss during a cool and clear night. The effects of microclimatic conditions resulting in dew or hoar‐frost formation on the plant were investigated, as well as the temperature range where freezing occurs.The results provide no evidence that the embedding of aLithopsplant into the soil yields advantages to the plants in respect of critical low or high temperatures. Plant temperatures are always very close to the soil temperatures at the same depth, but heat fluxes from the bottom or the plant and its surrounding soil to the top of the plant can occur if the plant freezes. No positive effect on the temperature relations could be detected when dew or hoar‐frost is formed on the top of the plant.Lithopsis frost hard to at least –3°C.
Significance of inhibition of seed germination under the leaf canopy in ash coppice
Authors: PONS T. L. 
Published: April 2006

Abstract. The effect on seed germination of the red/far‐red ratio of light (ζ) as modified by a leaf canopy was studied. The artificial light sources used and daylight filtered through leaves appeared to have identical effects in tests with lettuce seed.The sensitivity of the seeds to ζ varied with the environmental conditions during pretreatment and during the actual germination test. Freshly harvested and dry‐stored seeds of Cirsium palustre were strongly inhibited at low ζ; after stratification, the inhibition was much less. The fact that C. palustre emerges mainly after the coppice is felled could not be explained from these results combined with field data on ζ and the response of germination to temperature.The ecological significance of inhibition at low ζ is to be found directly after dispersal. Seed germination will then be delayed until the following spring or later. Geum urbanum showed primary dormancy, which was released by a stratification treatment. No inhibition of germination at low ζ was found in the spring and seeds germinated in light and darkness at low temperatures. These results explain why the species emerges early in spring regardless of the presence of the ash canopy.
Accumulation and conversion of sugars by developing wheat grains. 3. Non‐diffusional uptake of sucrose, the substrate preferred by endosperm slices
Authors: RIJVEN A. H. G. C. , GIFFORD R. M. 
Published: April 2006

Abstract. Starch synthesis by developing wheat endosperm slices incubated in liquid media was more rapid, at optimum concentration, from sucrose as external substrate than from glucose and/or fructose. Fructose inhibited conversion of sucrose or glucose. The results are consistent with the hypothesis that sucrose is not hydrolysed in the apoplast before uptake.Besides a diffusional influx and efflux of labelled sucrose there was a non‐diffusional influx; it was inhibited by dinitrophenol, potassium arsenate, potassium iodide, and parachloromercuribenzene sulphonate (PCMBS). PCMBS inhibited both uptake and conversion of label from 150 molm−314C‐sucrose by 75%. Uptake and conversion of sucrose were stimulated by lowering pH and by fusicoccin, a promoter of proton extrusion.Extracellular solutes like raffinosc and polyethylene glycol stimulated net uptake of label from 14C‐sucrose — the larger molecule being more effective — this being due to a non‐specific inhibition of diffusional efflux. At too high an osmotic concentration such solutes reduced net uptake; the larger the molecule the lower this transitional concentration.In conclusion, wheat endosperm is better equipped to convert apoplastic sucrose rather than the hydrolysis products to starch; active loading of sucrose possibly involves proton co‐transport; and large molecules in the extracellular solution reduce the diffusional elllux of loaded substrate.
Calcium in fungi
Authors: PITT D. , UGALDE U. O. 
Published: April 2006

Abstract. Recently much experimental evidence has accumulated concerning intracellular calcium and its fundamental role as a regulator in eukaryotic cells. The literature relating to Ca2+ in fungi is large and diverse and this paper draws together the available information and discusses the particular functions of the ion in this group of organisms.Uptake mechanisms in fungi are considered with special reference to the effect of Ca2+ on permeability and the systems responsible for transport of ions, sugars and amino acids. Discussion of the subcellular locations and distribution of Ca2+ is accompanied by a critique of methodology used in determination of subcellular sites of Ca2+ in fungi. The role of Ca2+ in morphogenesis in fungi is considered with particular reference to selected groups.
Specific action of blue light on phytochrome‐mediated enzyme syntheses in the shoot of milo (Sorghum vulgare Pers.)
Authors: OELMÜLLER R. , MOHR H. 
Published: April 2006

Abstract. This paper describes the effect of prolonged treatments with red or blue light on the capacity of the milo (Sorghum vulgare Pers.) shoot to respond to Pfr in subsequent darkness. Two groups of enzymes were studied. In group I (NADP‐dependent glyceraldehyde‐3‐phosphate dehydrogenase, NADP‐GPD. EC 1.2.1.13 and ribulose‐bisphosphate carboxylase, carboxylase, EC 4.1.1.39) enzyme formation is strongly enhanced by red light pulses (operating through phytochrome) whereas in group II (NAD‐dependent glyceraldehyde‐3‐phosphate dehydrogenase, NAD‐GPD, EC 1.2.1.12 and NAD‐dependent malate dehydrogenase, MDH. EC 1.1.1.37) enzyme formation hardly responds to red light pulses.In group 1 a 24‐h treatment with blue light (but not with red light) leads to a strong increase in responsivity to Pfr whereas in group II a 24‐h treatment with blue or red light does not increase responsivity to Pfr in subsequent darkness.The specific effect of blue light cannot be explained by an effect of light on gross protein synthesis. Rather, the data indicate that amplification of responsivity to Pfr by blue light is a specific process directly related to the mechanism of modulation of gene expression by phytochrome.
An analysis of resistance to water flow through wheat and tall fescue leaves during pressure chamber efflux experiments
Authors: STROSHINE R. L. , RAND R. H. , COOKE J. R. , CUTLER J. M. , CHABOT JEAN F. 
Published: April 2006

Abstract. This is a physical analysis of water movement in wheat (Triticum) and tall fescue (Festuca arundinacea) leaves placed in the Scholander pressure chamber. It takes into account the efflux resistances of water movement through the xylem and water flow across the cell membranes. Xylem resistance was estimated using Poiseuille's law.Leaves which had been pressurized in the chamber were embedded, sectioned, examined under a light microscope and photographed. Cells were intact but distorted and xylem vessels were intact. Cells in portions of the blade squeezed by the chamber sealing grommet were crushed, but xylem vessels remained intact.By applying pressure several tenths of a megapascal in excess of the balance pressure, water was forced from each leaf through the severed end which protruded from the chamber. Efflux curves were drawn by plotting the total water expressed as a function of time after the pressure increase. Water efflux from the shortest wheat leaf lasted only 10 min while efflux from the longest continued for up to 40 min. The efflux from a tall fescue leaf which was rehydrated and cut to a shorter length was much more rapid than efflux from the original leaf.Experiments combined with mathematical analysis suggested that the effect of leaf length on efflux is related to a high resistance to water flow through vascular bundles. Xylem resistance would be sufficient to produce this effect if it were 10 times greater than that predicted by Poiseuille's law. Both the observations of water flow from the cut end of the leaf and the mathematical model suggested very little water flows from bundles with vessels of diameter less than 12 μm. The apparent explanation is high resistance to water flow through these small diameter vessels.