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Notes: Abstract Some anomalous TV receptions in India on band I have been interpreted as being propagated viaF-layer artificially modified by high power broadcast transmitters. In this paper, the possibility of VHF communication by artificially modifiedE-layer is discussed. The presented theoretical analysis shows that high-power broadcast trasmitters can produce substantial changes in temperature and ionisation in theE-layer. The rate of energy transfer from the wave to the medium particles has also been computed. Model calculations are made for a transmitter located near Calcutta. The possibility of the extra-ionisation producing field-aligned structures to support VHF communication is discussed.

Notes: Ray achenes of Parthenium hysterophorus L. from widely separated localities showed a positive relationship between length and weight, and those from northern India (higher latitude) were heavier than those from the south (lower latitude). The achenes germinated well in continuous light and in the dark, but maximum germination was obtained with a 10-h photoperiod. Increasing duration of light pretreatment from 6 to 48 h resulted in greater subsequent germination in the dark. The achenes germinated over a wide range of alternating temperature regimes, but achieved maximum percentage germination at 25–30°C/15–20°C. Despite significant quantitative variation, the overall germination behaviour of achenes of different sizes was similar, although large achenes always gave higher germination than small ones. Germination was significantly influenced by seed source. The north Indian populations showed higher percentage germination than those from south India. The patterns of response of achenes of different provenances to light and alternating diurnal temperatures were slightly different.Germination des akènes de Parthenium hysterophorus L.: effets de lu lumière, température et de la taille et origine des akènesDes akènes de Parthénium hysterophorus L. issus de localités très largement éloignées ont montré une corrélation positive entre la longueur et le poids; ceux du nord de l'Inde (latitude plus élevée) étaient plus lourds que ceux du sud (latitude plus basse). Les akènes ont bien germés tant en lumière continue, qu'à l'obscurité, mais le maximum de germination a été observé sous une photopériode de 10 heures. Une augmentation d'une préexposition à la lumière de 6 h à 48 h aboutit ensuite à une plus grande germination à l'obscurité. Les akènes ont germé sur un très large éventail de régimes de températures alternées mais on a obtenu le maximum de pourcentage de germination à 25–30°C/15–20°C. En dépit de variations quantitatives significatives, le comportement général de germination des akènes de tailles différentes a été comparable, même si les grands akènes germent toujours mieux que les petits. La germination est influencée de façon significative par la provenance de la graine. Les populations du nord de l'Inde expriment un pourcentage de germination plus élevé que celles du sud. Les comportements de réponse des akènes de différentes provenances à la lumière, et aux températures diurnes ont été légèrement différentes.Keimung der Achänen von Parthenium hysterophorus L.: Wirkung von Licht, Temperatur und Herkunft sowie Grösse der AchänenDie Achänen von Parthenium hysterophorus L. von weit voneinander liegenden Orten zeigten ein positives Längen-Gewicht-Verhältnis, wobei sie in Nordindien schwerer waren als im Süden. Die Achänen keimten im Dauerlicht und im Dunkeln gut, aber bei 10stündiger Lichtperiode am besten. Wenn sie zunächst einer von 6 bis auf 48 h gesteigerten Licht-Behandlung unterworfen wurden, keimten sie im Dunkeln besser. Die Achänen keimten über eine weite Spanne wechselnder Temperatur; die maximale Keimrate wurde bei 25–30/15–20°C gefunden. Trotz signifikanter Unterschiede war die Keimung verschieden grosser Achänen im grossen und ganzen ähnlich, wenn auch die grossen immer stärker als die kleinen keimten. Die Keimung war signifikant von der Herkunft beeinflusst: Die Achänen aus Nordindien hatten eine grössere Keimrate als die aus dem Süden. Das Verhalten der Achänen verschiedener Herkunft gegenüber Licht und wechselnder Tagestemperatur war wenig unterschiedlich.

Notes: Summary The compound, 3,5-dibromo-2′-chloro-4′-isothiocyanatosalicylanilide, has been tested against various nematode and cestode parasites in experimental and domestric animals. It shoved 100% activity againstAncylostoma ceylanicum, A. tubaeformis, Syphacia obvelata, Ascaridia galli, Toxocara spp.,Toxascaris sp.,Gnathostoma spinigerum, Hymenolepis nana, Raillietina spp. andTaenia spp. in doses 25–70 mg/kg given in single or multiple administrations.

Notes: Summary The toxicity of chromium and tin on growth, photosynthetic carbon-fixation, oxygen evolution, heterocyst differentiation and nitrogenase activity ofAnabaena doliolum and its interaction with bivalent cations has been studied. Some interacting cations, viz. Ca2+, Mg2+ and Mn2+, substantially antagonised the toxic effects of chromium and tin with reference to growth, heterocyst differentiation and nitrogenase activity in the following hierarchal sequence: Ca2+ 〉 Mg2+ 〉 Mn2+. However, the sequence of hierarchy was Mg2+ 〉 Ca2+ 〉 Mn2+ for carbon fixation and Mn2+ 〉 Mg2+ 〉 Ca2+ for photosynthetic oxygen evolution. Synergistically inhibitory patterns were noticed for all the parameters, viz. growth,14CO2 uptake, oxygen evolution, heterocyst differentiation and nitrogenase activity ofA. doliolum when Ni2+, Co2+ and Zn2+ were combined with the test metals in the growth medium. These cations followed the following sequence of synergistic inhibition: Ni2+ 〉 Co2+ 〉 Zn2+. Among all the interacting cations, Ca2+, Mg2+ and Mn2+ exhibited antagonistic effects which relieved the test cyanobacterium from metal toxicity. In contrast to this, Ni2+, CO2+ and Zn2+ showed synergistic inhibition which potentiating the toxicity of test metals in the N2-fixing cyanobacteriumA. doliolum. It is evident from the present study that bivalent cations, viz. Ca2+, Mg2+, Mn2+, Ni2+, Co2+ and Zn2+, may appreciably regulate the toxicity of heavy metals in N2-fixing cyanobacteria if present in aquatic media.

Notes: Abstract The high/low-amplitude anisotropic wave train events (HAE/LAE) in CR intensity have been investigated during the period 1981–1990, using the neutron monitoring data for different latitudes. In all, 21 HAE and 15 LAE cases have been studied. It has been observed that the phase of the diurnal anisotropy remains in the same co-rotational direction for the majority of the HAE/LAE cases. However, it has also been observed that the phase of the diurnal anisotropy changes to later hours in some of the HAE cases, whereas it changes to early hours in some of the LAE cases. Further, the amplitude of the semi-diurnal anisotropy for HAE/LAE cases remains statistically the same; however, the phase of the semi-diurnal anisotropy for HAE has been found to shift to later hours for all events. Furthermore, the HAE occur dominantly during the declining phase of solar activity, whereas LAE occur dominantly during the minimum solar activity period. The geomagnetic activity index-Ap has been observed to remain low during the period of each HAE/LAE. The possible phenomenon to cause the enhanced/low-amplitude daily variation has been proposed to appear on the back side of the Sun.

Notes: Abstract An expression for the susceptibility dyadic appropriate to the lower regions of the atmospheric plasma is derived using Maxwell's field equations and the equation of conservation of momentum. The contributions due to viscous effect and convection current density are incorporated in the physical processes within the stated medium. Utilizing the approximation of linearized equations, second order coupled wave equations have been derived through the dyadic.

Notes: Summary This study presents the effects of Cr, Pb, Ni and Ag on growth, pigments, protein, DNA, RNA, heterocyst frequency, uptake of NH4 + and N03 −, loss of electrolytes (Na+ and K+), nitrate reductase and glutamine synthetase activities ofNostoc muscorum. The statistical tests revealed a direct positive correlation between the metal concentration and inhibition of different processes. Ni was found to be more toxic against growth, pigments and heterocyst differentiation compared to the other metals. Inhibition of pigment showed the following trend: chlorophyll 〉 phycocyanin 〉 carotenoid. No generalized trend for inhibition of macromolecules was observed. The loss of K+ and Na+ as affected by Cr, Ni and Pb was similar but more pronounced for K+ than Na+. The inhibition of physiological variables depicted the following trend: Na+ loss 〉 K+ loss 〉 glutamine synthetase 〉 NH4 uptake 〉 growth 〉 N03 − uptake 〉 nitrate reductase 〉 heterocyst frequency. This study therefore suggests that loss of electrolytes can be used as a first signal of metal toxicity in cyanobacteria. However, further study is needed to confirm whether the abnormality induced by nickel (branch formation) is a physiological or genetic phenomenon.

Notes: Abstract The impact of 2,4-dinitrophenol and chlorophenyl dimethylurea on ATP content carbon fixation, O2 evolution, nitrogenase activity and Cr uptake ofAnabaena doliolum has been studied. 2,4-Dinitrophenol has been found to be more toxic than chlorophenyldimethylurea for all these processes. However, when Cr toxicity to above variables was assessed in their presence the interaction was less than additive. An initial (10–15 min) concentration-dependent rapid Cr uptake, followed by a slow one, indicates a biphasic uptake. A significant inhibition of Cr uptake in the presence of both these metabolic inhibitors suggests the involvement of metabolic processes in Cr uptake.