Efficaciousness of Certain Chemicals to Control Dracunculiasis — A Field Trial     

S. Mehta  R. C. Srivastava 《洁净——土壤、空气、水》1984,12(3):291-300

To prevent infection with Dracunculus medinensis, a carrier host, the copepod Cyclops, has to be controlled. After preceding laboratory investigations a field trial with well water and different additions of chlorine and sodium permanganate is carried out. The exposure is performed at an ambient temperature of 25… 40 °C and in bright and dark samples (5… 11 h of sunshine/d) as well as in the well. The residual concentrations of the two chemicals are an exponential function of the time of exposure with half-times between 6 and 23 h for chlorine and 11… 30 h for sodium permanganate. The depletion of the two oxidizing agents under light is faster than in darkness. Dosage should be done in such a way that the LC_90,24h after 24 h of exposure will not be fallen below; in a specific case, this guarantees at the same time that the permissible concentrations for drinking water will not be reached 96 h after addition. For this, initial concentrations of 30 mg 1 Cl₂ or 50 mg/l KMnO_r are necessary. Under these conditions, the Cyclops population had died on the seventh day after the application of chemicals, but after seven weeks it reached the original density again. With one application of chloride or sodium permanganate a week Dracunculiasis can be completely controlled.  相似文献   

Relative Toxicity of Some Non-Insecticidal Chemicals to the Free Living Larvae Guinea-Worm (Dracunculus medinensis)     

S. Mehta  R. C. Srivastava  A. N. Gupta 《洁净——土壤、空气、水》1982,10(4):397-400

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Political economy of population growth     

Mehta S  Mehta HS 《Population geography : a journal of the Association of Population Geographers of India》1987,9(1-2):1-15

Tracing the origin of political economy as a class-science, this paper focuses on the political economy of population growth. Exposing the limitations of Malthusian ideas and their invalidity even for the capitalist economies, it discusses the subsequent revival of the Malthusian model during the period of de-colonization and the misinterpretation of the relationship between population growth and development in the developing and developed countries. Taking India, China, and Japan as some case studies, the paper examines the relationship between birth rate levels and some correlates. It elaborates on the Indian experience, emphasizing the association of population growth with poverty and unemployment and lays bare some of the hidden causes of these phenomena. The authors examine some interstate variations in India and identify constraints and prospects of the existing population policy. The paper proposes outlines of a democratic population policy as an integral part of India's development strategy which should recognize human beings not simply as consumers but also as producers of material values. It pleads for 1) restructuring of property relations; 2) bringing down the mortality rates and raising of the literacy levels, especially among females; and 3) improving nutritional levels, as prerequisites for bringing down birth rates.  相似文献   

Zur Chemie der organischen Substanz des Bodens     

Prof. Dr. H. Deuel  Dr. P. Dubach  Dr. N. C. Mehta  Dr. R. Bach 《Aquatic Sciences - Research Across Boundaries》1960,22(1):111-121

Zusammenfassung Die heutigen Kenntnisse über die Chemie der organischen Substanz des Bodens werden kurz besprochen. In der organischen Substanz des Bodens ist schon eine Reihe von Verbindungen nachgewiesen worden. über die Chemie der braunen Huminstoffe ist hingegen noch sehr wenig bekannt. Es wird über neuere Untersuchungen an Kohlehydraten berichtet. Die quantitative Bestimmung der gesamten Kohlehydrate und der einzelnen Zucker des Bodens ist noch nicht befriedigend gel?st. Eingehend wurde die Bestimmung der Urons?uren und Pentosen studiert. Polysaccharide konnten nur in geringen Mengen isoliert werden. Ein Polysaccharidpr?parat wurde chromatographisch in verschiedene Fraktionen zerlegt. Die Bodenkrümelung ist nicht in erster Linie auf Polysaccharide zurückzuführen. Huminstoffe aus einem Podsol-B-Horizont wurden fraktioniert. Die gereinigten Fraktionen sind sehr reaktionsf?hig; sie wurden mit verschiedenen chemischen und physikalisch-chemischen Methoden charakterisiert. Diese Fraktionen stellen vielleicht eine Reihe von strukturell nahe verwandten Verbindungen dar.  相似文献   

Population and development linkages: perspectives and research tasks     

Mehta S 《Population geography : a journal of the Association of Population Geographers of India》1993,15(1-2):23-28

The author argues that the linkages between population and development are too complex to be understood in a narrow cause-effect frame. It is suggested that population policies designed to lower birth rates have succeeded only where certain prerequisites could be created. Focussing upon some of the popular perspectives, the author's study indicates research tasks and questions which, if pursued seriously, can help in comprehending the multidimensionality of population-development relationships. Sections discuss perspectives; a dichotomous world scenario with regard to population growth and development; the myth and reality in the mismatch between world population growth and potential resources in the context of technological developments; status, gaps, and tasks in population research in geography; population growth; determinants of population growth; and literacy and education.  相似文献   

The role of organized tropical storms and cyclones on intraseasonal oscillations in the Asian monsoon domain based on INSAT satellite measurements     

E. A. Smith  A. V. Mehta 《Meteorology and Atmospheric Physics》1990,44(1-4):195-218

Summary The role of organized tropical storms and typhoons within the West Pacific-Indian Ocean dipole of low frequency activity is examined with the aid of INSAT satellite observations. Two Asian summer monsoon seasons-1984 and 1987-are analyzed in conjunction with a satellite derived convective index. The former year was noted as an above average Indian monsoon; the latter year as an extreme Indian monsoon failure.The analysis demonstrates that the dipole region is actually an organized collection of seven smaller scale high amplitude, low frequency centers which blur together to form the semblance of a dipole which had been originally identified in 2.5° resolution outgoing Longwave Radiation (OLR) data derived from NOAA satellite measurements. The centers are basically situated over oceanic regions in the eastern and western sectors of the dipole, although, an isolated high amplitude center is also found over central Tibet. Of considerable interest is that the locations of the seven centers, whereas not equivalent, are very similar for both the 1984 and 1987 seasonsinar.The analysis indicates that there are coherent phase relationships between the eastern sector of the dipole and the western sector, but that it is not a simple dipole-like process. Rather, the four high amplitude centers, within the western sector, all fall within a longitudinal channel in which the well known, northward propagating behavior of Monsoon convection anomalies serves to modulate the east-west phase lag along the meridional channel. The result is that the western paelfic phase lags the equatorial Indian Ocean center whereas it generally phase leads the more northern centers within the Arabian Sea and Bay of Bengal. In the two years studied here, there is little evidence of east-west propagation of anomalies between he two centers.The contribution of organized tropical storms and cyclones to the amplitude and phase characteristics of the high amplitude centers is irregular but important, particularly in the eastern sector of the dipole, where up to 50% of the variance can be explained by organized storms. It is also shown that the influence of storms on the phase propagation characteristics of convective anomalies is irregular but significant.With 14 Figures  相似文献   

Macro-zonation of landslide susceptibility in Garamaura-Swarghat-Gambhar section of national highway 21, Bilaspur District, Himachal Pradesh (India)     

R. K. Sharma  B. S. Mehta 《Natural Hazards》2012,60(2):671-688

Landslides the most common geo-hazard in hilly terrain are short lived phenomena but cause extraordinary landscape changes and destruction of life and property. The frequency and intensity of landslides occurrences along NH-21 during the rainy season not only disrupts traffic movement but also misbalance the agro-economic and developmental activities of the region frittering away thousand crores of rupees from the exchequer. An assessment of landslide susceptibility is, therefore, a prerequisite for sustainable development of the region. The present study deals with the preparation of macro-zonation maps of landslide susceptibility in an area of about 100 sq km on 1:50,000 scale across Garamaura-Swarghat section of National Highway-21. The map has been prepared by superimposing the terrain evaluation maps in a particular zone such as lithological map, structural map, slope morphometry map, relative relief map, land use and land cover map and hydrological condition map using landslide susceptibility evaluation factor rating scheme and calculating the total estimated susceptibility as per the guidelines of IS: 14496 (Part-2) 1998). Numerical weightages are assigned to the prime causative factors of slope instability such as lithology, structure, slope morphometery, relative relief, land use and groundwater conditions as per the scheme approved by Bureau of Indian Standard for the purpose of landslide susceptibility zonation. The area depicts zones of different instability. The identified susceptibility zones compared with landslide intensity in the area show some congruence with the weightages of the inputs. The incongruence in intensity and frequency of landslide occurrences and the inferred susceptibility zones of BIS scheme allow other geotechnical considerations and causative factors to be incorporated for the landslide susceptibility zonation.  相似文献   

Tectonostratigraphic status of the proterozoic Babarmal pink marble from the Aravalli Supergroup     

Ritesh Purohit  Harsh Bhu  Prakshal Mehta  P. C. Avadich 《Journal of the Geological Society of India》2012,79(2):135-150

Present study reviews the tectono-stratigraphic status of Babarmal pink marble from the Aravalli Supergroup through mapping and petrographic study of marble as well as associated lithologies. The pink marble is predominantly calcitic and characteristically different from dolomitic carbonate rocks of the Jhamarkotra Formation, the Lower Aravalli Group. The marble is devoid of organic matter and phosphate content unlike the Jhamarkotra dolomite. The pink marble is underlain by quartz-pebble rich conglomerate. This assemblage represents a rare lithological association which has not been reported so far from the Aravalli Supergroup.  相似文献   

The Value of Wastewater Derived Struvite as a Source of Phosphorus Fertilizer          下载免费PDF全文

Chirag M. Mehta  Malcolm N. Hunter  Gaius Leong  Damien J. Batstone 《洁净——土壤、空气、水》2018,46(7)

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