The rates of nitrification of peat soils in British Guiana

1954 ◽  
Vol 44 (4) ◽  
pp. 377-382 ◽  
Author(s):  
H. Paul ◽  
M. A. A. Shariff
Keyword(s):  
Field Experiments ◽  
Ammonia Nitrogen ◽  
The Other ◽  
Appreciable Amount ◽  
Continuous Cropping ◽  
Peat Soils ◽  
British Guiana ◽  
Other Hand ◽  
Short Period ◽  
Before And After

A study has been made of some of the nitrogen fractions of the pegasse soils of British Guiana in virgin and exhausted conditions, that is, before and after cropping.1. Preliminary field experiments on the virgin and exhausted soils adduced strong evidence in support of the complaints made by farmers that the productivity in yields of the pegasse soils after continuous cropping for a comparatively short period is considerably impaired.2. The virgin soil showed an appreciable amount of nitrate nitrogen, while the exhausted sample indicated no nitrate. The latter soil, on the other hand, contained a higher amount of ammonia nitrogen measured by KCl extraction than the former soil.3. Nitrification studies with added ammonium salts indicated that under optimum conditions the nitrifying power of the exhausted soil was extremely low. Additions of sodium nitrate indicated that the nitrate was partially reduced to ammonia by the worn-out pegasse soil. The virgin pegasse, on the other hand, showed an appreciable rate of nitrification.

An assessment of the factors controlling the productivity of maize in England

1951 ◽  
Vol 41 (3) ◽  
pp. 271-281 ◽  
Author(s):  
E. S. Bunting ◽  
G. E. Blackman
Keyword(s):  
Dry Matter ◽  
Field Experiments ◽  
Plant Density ◽  
Spatial Arrangement ◽  
The Other ◽  
Mass Selection ◽  
Grain Production ◽  
Forage Production ◽  
Field Scale ◽  
Other Hand

Between 1942 and 1950, some thirty field experiments have been carried out in the southern half of England to assess the potential value, either for grain or forage production, of seventeen openpollinated flint or dent maizes together with twentynine single or double hybrids of American or Canadian origin.Early-maturing flint varieties will consistently ripen grain, but before mechanical threshing or storage, the cobs require drying. Sibthorp, a mass selection made from an unknown German variety, is the earliest and most productive flint maize so far tested, and in the experiments has yielded as much as 39 cwt. of grain per acre with an average of 24 cwt. The earliest American hybrids, i.e. those with a U.S.A. rating of 80 days from sowing to maturity, give very high yields of grain in favourable seasons. Within the group Wisconsin 240–275, a yield level equal to or exceeding 50 cwt./acre has on occasion been recorded. On the other hand, in the most unfavourable years, such hybrids just failed to produce ripe cobs.Attempts to maintain sixty-five parent inlines of the earliest hybrids have largely failed. However, many of the parent single crosses have matured, and the production on a field scale of the double-cross seed of both Wisconsin 240 and 255 has been carried out.Spacing experiments indicate that for optimum grain production a density of 6 plants/sq.yd. is required for both flint varieties and the earliest hybrids. A spatial arrangement of individual plants is to be preferred to that of groups or hills.American hybrids, in the class of ‘90 days’ to maturity, will in all but the most unfavourable seasons reach the ‘early-dent’ stage of the grain before the incidence of autumn frosts. Yields of dry matter of plants harvested in this phase have ranged from 30 to 85 cwt. of dry matter per acre. In these trials, the plant density was standardized at 4 plants/sq.yd. and higher densities may be demanded for optimal yields.The ratio of the ‘ear’ (that is, the cob, immature grain and enclosing leaf sheaths) to the total shoot weight at harvest varies greatly with the variety or hybrid. With White Horsetooth, the usual variety grown for fodder in England, no cobs are formed before the plants are killed by frost, while with the early hybrids, the ear may be half the weight of the whole shoot.The earliest variety Sibthorp from an early May sowing takes approximately 70–80 days to reach full anthesis, while ‘80-day’ American hybrids are a week later. From sowing to full maturity the period in England is from 140 to 160 days, thus compared to conditions in Minnesota the period is nearly twice as long. Because of the much slower rate of development and because of the humidity of English autumns, it is concluded that until the date of maturity can be advanced some 14 days, grain production on a field scale is not yet feasible. On the other hand, many of the American hybrids are well fitted to the production of silage. The greatest drawback to the introduction of such hybrids is the liability of the seed and seedlings to be attacked by rooks.

scholarly journals The Effect of Geogebra on Students’ Conceptual and Procedural Knowledge: The Case of Applications of Derivative

2017 ◽  
Vol 7 (2) ◽  
pp. 67 ◽  
Author(s):  
Mehmet Fatih Ocal
Keyword(s):  
Conceptual Knowledge ◽  
Teaching And Learning ◽  
Procedural Knowledge ◽  
Dynamic Geometry ◽  
The Other ◽  
Control Group ◽  
Other Hand ◽  
Significant Difference ◽  
Before And After ◽  
Post Test

Integrating the properties of computer algebra systems and dynamic geometry environments, Geogebra became an effective and powerful tool for teaching and learning mathematics. One of the reasons that teachers use Geogebra in mathematics classrooms is to make students learn mathematics meaningfully and conceptually. From this perspective, the purpose of this study was to investigate whether instruction with Geogebra has effect on students’ achievements regarding their conceptual and procedural knowledge on the applications of derivative subject. This study adopted the quantitative approach with pre-test post-test control group true experimental design. The participants were composed of two calculus classrooms involving 31 and 24 students, respectively. The experimental group with 31 students received instruction with Geogebra while the control group received traditional instruction in learning the applications of derivative. Independent samples t-test was used in the analysis of the data gathered from students’ responses to Applications of Derivative Test which was subjected to them before and after teaching processes. The findings indicated that instruction with Geogebra had positive effect on students’ scores regarding conceptual knowledge and their overall scores. On the other hand, there was no significant difference between experimental and control group students’ scores regarding procedural knowledge. It could be concluded that students in both groups were focused on procedural knowledge to be successful in learning calculus subjects including applications of derivative in both groups. On the other hand, instruction with Geogebra supported students’ learning these subjects meaningfully and conceptually.

scholarly journals Improved Bathymetric Mapping of Coastal and Lake Environments Using Sentinel-2 and Landsat-8 Images

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2788 ◽  
Author(s):  
Ali P. Yunus ◽  
Jie Dou ◽  
Xuan Song ◽  
Ram Avtar
Keyword(s):  
Empirical Approach ◽  
The Other ◽  
Landsat 8 ◽  
Mobile Bay ◽  
Transport Pathways ◽  
Other Hand ◽  
Crucial Component ◽  
Short Period ◽  
Bathymetric Mapping ◽  
Sentinel 2

The bathymetry of nearshore coastal environments and lakes is constantly reworking because of the change in the patterns of energy dispersal and related sediment transport pathways. Therefore, updated and accurate bathymetric models are a crucial component in providing necessary information for scientific, managerial, and geographical studies. Recent advances in satellite technology revolutionized the acquisition of bathymetric profiles, offering new vistas in mapping. This contribution analyzed the suitability of Sentinel-2 and Landsat-8 images for bathymetric mapping of coastal and lake environments. The bathymetric algorithm was developed using an empirical approach and a random forest (RF) model based on the available high-resolution LiDAR bathymetric data for Mobile Bay, Tampa Bay, and Lake Huron regions obtained from the National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center (NGDC). Our results demonstrate that the satellite-derived bathymetry is efficient for retrieving depths up to 10 m for coastal regions and up to 30 m for the lake environment. While using the empirical approach, the root-mean-square error (RMSE) varied between 1.99 m and 4.74 m for the three regions. The RF model, on the other hand, provided an improved bathymetric model with RMSE between 1.13 m and 1.95 m. The comparative assessment suggests that Sentinel-2 has a slight edge over Landsat-8 images while employing the empirical approach. On the other hand, the RF model shows that Landsat-8 retrieves a better bathymetric model than Sentinel-2. Our work demonstrated that the freely available Sentinel-2 and Landsat-8 imageries proved to be reliable data for acquiring updated bathymetric information for large areas in a short period.

scholarly journals A Collimated Molecular Jet in W 43A Traced by Water Maser Emission

2003 ◽  
Vol 209 ◽  
pp. 267-268
Author(s):  
Hiroshi Imai ◽  
Tetsuo Sasao ◽  
Kumiko Obara ◽  
Toshihiro Omodaka ◽  
Philip J. Diamond
Keyword(s):  
Planetary Nebula ◽  
Stellar Object ◽  
The Other ◽  
Maser Emission ◽  
Other Hand ◽  
Systemic Velocity ◽  
Short Period ◽  
The Common ◽  
Water Maser

We present VLBA observations of the spatial and velocity distributions of 22 GHz H2O and 1612 MHz OH masers in the OH/IR star W 43A. These masers have the same systemic velocity and are, therefore, likely to be associated with the common stellar object. However, the kinematical structures of them are quite different and independent. Most of the H2O masers are extremely collimated spatially and kinematically. The H2O maser jet also seems to be precessing. On the other hand, the OH masers exhibit clear arc-shaped structures indicating a spherically-expanding shell with weak collimation. The W 43A jet is very likely to be predominantly composed of hot molecules traced by H2O maser emission and formed in the immediate vicinity of an unknown star next to another OH/IR star. Such a “molecular jet” is likely to appear only during the short period before a star forms an elongated planetary nebula.

Effects of chest wall compressions in kittens

1982 ◽  
Vol 60 (10) ◽  
pp. 1241-1246 ◽  
Author(s):  
T. Trippenbach ◽  
C. Gaultier ◽  
L. Cooper
Keyword(s):  
Chest Wall ◽  
Chest Compression ◽  
The Other ◽  
Peak Amplitude ◽  
Inspiratory Time ◽  
Chest Compressions ◽  
Mean Values ◽  
Control Value ◽  
Other Hand ◽  
Before And After

Effects of chest compressions on the pattern of breathing were studied in pentobarbital anaesthetized 9- to 11-day-old kittens before and after vagotomy. The chest was compressed by means of a micrometer at three levels (T1–4, T6–8, T9–11). In intact and vagotomized kittens, the group mean values of inspiratory time (tI), expiratory (tE) time, peak amplitude of the integrated phrenic activity (PHR) and its rate of rise (PHR/tI) during compressions were not different from those of the control breaths. On the other hand, in intact kittens during chest compressions variability of all the measured variables significantly increased. In the vagotomized kittens, variability of parameters other than inspiratory time was unaffected. Nevertheless we cannot exclude contribution of extravagal receptors in control of tE. The tE effects could be masked by the increased variability of the control value in vagotomized kittens. The effects of chest compression on the integrated phrenic activity were mostly dependent on the intact vagal feedback.

scholarly journals The influence of desiccation and UV radiation on the development and survival of free-living stages of cyathostomins under field and laboratory conditions

2008 ◽  
Vol 45 (1) ◽  
pp. 32-40 ◽  
Author(s):  
I. Langrová ◽  
I. Jankovská ◽  
J. Vadlejch ◽  
M. Libra ◽  
A. Lytvynets ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Field Experiments ◽  
The Other ◽  
Infective Stage ◽  
Free Living ◽  
Infective Larvae ◽  
Laboratory Conditions ◽  
Other Hand ◽  
Field And Laboratory Conditions

AbstractThe present work describing both laboratory and field experiments was performed to assess the effects of desiccation and UV radiation on the development and survival of free-living stages of equine cyathostomins.Cyathostomin larvae in horse faeces did not develop to the infective stage when faecal humidity levels dropped below 23 %, nonetheless solitary preinfective larvae were still recovered after 151 days (humidity 19.5 %). The development to infective stage after remoistening occurred for the last time after 54 days following desiccation.Preinfective stages are susceptible to the effects of the direct desiccation stage. The preinfective larvae were rapidly killed within one minute, the cyathostomin eggs within 5 hours. The numerous normal mobile infective larvae were encountered after 35 days of the desiccated period. The preinfective stage of cyathostomins also showed very little tolerance to direct sun radiation: most eggs were killed by the exposure within 3 hours and the preinfective larvae within 1 hour. The survival of infective larvae was, on the other hand, unaffected by sun radiation after 7 days (P < 0.05). However, desiccated infective larvae were then found to be susceptible to UV radiation, resulting in total mortalities after 5 days.

Differences in ouabain-induced natriuresis between isolated kidneys of Milan hypertensive and normotensive rats

1992 ◽  
Vol 82 (2) ◽  
pp. 185-190 ◽  
Author(s):  
Roland Foulkes ◽  
Romana G. Ferrario ◽  
Patricia Salvati ◽  
Giuseppe Bianchi
Keyword(s):  
Vascular Resistance ◽  
Receptor Occupancy ◽  
Renal Vascular Resistance ◽  
The Other ◽  
Hypertensive Rats ◽  
Other Hand ◽  
Before And After ◽  
Renal Vascular ◽  
Isolated Kidneys

1. Several observations support the hypothesis that in rats of the Milan hypertensive strain elevated levels of a circulating ouabain-like factor might normalize the elevated Na+ reabsorption, but, on the other hand, might contribute to the development of hypertension. 2. As the receptor occupancy of this endogenous factor seems to be reversible, the aim of our study was to test, in vitro, the hypothesis of its presence in isolated kidneys from Milan hypertensive rats by studying the response to exogenous ouabain before and after prolonged washing. 3. The kidneys were isolated from adult Milan hypertensive rats and from age-matched normotensive controls and ouabain was given at two different experimental time intervals: shortly (15 min) after washout or after a further 60 min of washout (75 min in total). Comparative experiments with the diuretic hydrochlorothiazide were performed using the same protocol. 4. Ouabain given after 15 min of perfusion caused an increase in renal vascular resistance, diuresis and natriuresis; these haemodynamic and tubular responses were similar in kidneys from both Milan hypertensive and Milan normotensive rats. If given after the washout period, ouabain caused a comparable increase in renal vascular resistance, but a significantly greater natriuresis in kidneys from Milan hypertensive rats as compared with kidneys from Milan normotensive rats. On the other hand, hydrochlorothiazide caused similar natriuresis in kidneys from both strains after washout. 5. These results support the hypothesis that a factor, capable of interacting with the ouabain receptor on the Na+/K+−ATPase of tubular cells, is present in the kidney of adult Milan hypertensive rats and that it can be removed by prolonged washout.

Digital platforms: mapping the territory of new technologies to fight food waste

2020 ◽  
Vol 122 (5) ◽  
pp. 1647-1669 ◽  
Author(s):  
Massimo Cane ◽  
Carmen Parra
Keyword(s):  
Food Waste ◽  
New Technologies ◽  
Point Of View ◽  
The Other ◽  
Theoretical Point ◽  
Content Type ◽  
Digital Platforms ◽  
Other Hand ◽  
Short Period ◽  
Responsible Consumption

PurposeThe reduction of food waste is still a pending issue that governments have still not resolved. In response to this problem mobile platforms are emerging that follow food ecology and the responsible consumption of food, and self-management of their access to allow the communication between people and their use of food. In this paper, the authors will analyze the main digital platforms that deal with solving this problem, especially those that fulfill a social commitment through the distribution and reduction of waste.Design/methodology/approachTo provide solutions, the authors will address the importance of new technologies in the fight against waste, using digital platforms to manage food and to eliminate the loss in surplus products. To do this, the authors will first analyze from a theoretical point of view the concepts of “loss”, “waste” and “surplus product”, incorporating data of their impact between Spain and Italy. Next, the authors will analyze the influence of new technologies in the detection and distribution of products destined to become food waste. To carry out this qualitative research, the authors will apply the research strategy of theory building from multiple case studies (particularly 16 different digital platforms against food waste were analyzed), which is a methodological approach that uses cases as the basis to develop theory inductively.FindingsThe authors must make the public aware of the importance of being responsible consumers. To this end, the authors must disclose the problems associated with food waste and surplus product, presenting alternatives and new consumption habits. For this, it is necessary to collaborate and build synergies with organizations of different origins (consumers, producers and activists) involved in sustainable agrifood models. In this sense, digital platforms are essential tools to fight against food waste, preventing certain products from being considered unfit for human consumption. In this study, the authors suggest that, based on the review of the literature and the analysis of apps and blogs, the authors look for solutions to surplus and food waste both from the environment of the entrepreneur and the consumer and all using the new technologies.Research limitations/implicationsThe research has raised different limitations. On the one hand, it is a subject that has not been analyzed from a doctrinal point of view, so it is not easy to find bibliographic references. On the other hand, digital platforms that act on food waste are not cataloged. This has made it difficult to search for elements of analysis to obtain results in the work. Finally, the sample can vary in a short period of time since the digital platforms are in a boom, which means that they constantly change.Practical implicationsThis work allows a theoretical approach to the concepts of “loss”, “wastage” and “surplus product”, incorporating data on its impact in Spain and Italy, comparing it with the rest of Europe while providing figures and data on their impact. On the other hand, it allows us to know how new technologies can help the detection and distribution of products destined to become food waste. Finally, there are examples of platforms that are offering service in different areas, incorporating a novel classification that allows us to know the differences depending on their origin and destination.Originality/valueThe originality of the work can be summarized in the following points: There are no doctrinal works that analyze in a combined way the food waste with the new technologies; The relationship with the 2030 Agenda in which responsible consumption is one of the achievements pursued by the United Nations, and the authors position the study’s research as an evidence of platforms that are currently working in the interest of reducing food waste. Furthermore, the authors provide an early classification of platforms based on their usability and objectives of reducing, reusing and recycling food.

RESUMPTION OF LACTATION BY SUCKLING IN LACTATING RATS AFTER REMOVAL OF LITTERS

1965 ◽  
Vol 33 (2) ◽  
pp. 185-194 ◽  
Author(s):  
K. ÔTA ◽  
A. YOKOYAMA
Keyword(s):  
Mammary Gland ◽  
Nucleic Acid ◽  
Acid Content ◽  
The Other ◽  
Tissue Structure ◽  
Nucleic Acid Content ◽  
Milk Secretion ◽  
Glandular Tissue ◽  
Other Hand ◽  
Short Period

SUMMARY Foster litters were given to lactating rats whose own litters had been removed 3, 5 or 9 days previously. Lactation was restored in all groups by this re-suckling procedure within a relatively short period. The restoration of lactation became more difficult as the interval between the removal of the original litters and the application of the foster litters increased. Changes in the nucleic acid content of the mammary gland after re-suckling were investigated in the rats whose litters were removed for 3 days before re-suckling. Both the DNAP content of the gland and its weight increased steadily in proportion to the length of the period of re-suckling, so that a fairly constant DNAP concentration was maintained in the tissue. The RNAP content and the RNAP:DNAP ratio, on the other hand, increased abruptly at about the time when milk secretion was initiated by re-suckling. The DNAP content continued to increase even after the onset of restored milk secretion. These results suggest that milk secretion after re-suckling began before full restoration of the tissue structure and that growth of the glandular tissue took place concurrently with milk secretion.

scholarly journals Dasein and World: Heidegger’s Reconceiving of the Transcendental After Husserl

2020 ◽  
Vol 1 (3) ◽  
pp. 265-287
Author(s):  
Niall Keane
Keyword(s):  
The Other ◽  
Constitutive Relationship ◽  
Being And Time ◽  
Husserlian Phenomenology ◽  
Early Analysis ◽  
Constitutive Analysis ◽  
Other Hand ◽  
The World ◽  
Before And After ◽  
The One

AbstractThe following examines Heidegger’s analysis of world and Dasein from a transcendental perspective. It is argued that Heidegger’s reflections on the interconnected themes of world and Dasein reveal the tensions that exist between the transcendental claims before and after Being and Time and the analysis of worldliness. It begins by looking at Heidegger’s early analysis of Husserl’s critique of psychologism and naturalism, assessing what this tells us about Heidegger’s analysis of world and nature. It subsequently addresses Heidegger’s transformation of Husserlian phenomenology, and intentionality in particular, arguing against interpreters who claim Heidegger’s interconnected concepts of Dasein and world are reducible to one another and hence phenomenologically problematic. In order to respond to this reading, the article examines the twin themes of, on the one hand, transcendental constitutive analysis in Heidegger’s work, Dasein as disclosive and ‘world entering’, and, on the other hand, the centrality of the world and the realm of nature as always more than Dasein’s constitutive relationship to it. In order to understand what Heidegger means by worldliness, the article will look at Heidegger’s reflections on nature as the world’s other, which nonetheless needs to be understood on the basis of worldliness.

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