Influence of dew on biomass and photosystem II activity of cyanobacterial crusts in the Hopq Desert, northwest China

Dew is an important water source for desert organisms in semiarid and arid regions. Both field and laboratory experiments were conducted to investigate the possible roles of dew in growth of biomass and photosynthetic activity within cyanobacterial crust. The cyanobacteria, Microcoleus vaginatus Gom. and Scytonema javanicum (Kutz.) Born et Flah., were begun with stock cultures and sequential mass cultivations, and then the field experiment was performed by inoculating the inocula onto shifting sand for forming cyanobacterial crust during late summer and autumn of 2007 in Hopq Desert, northwest China. Measurements of dew amount and Chlorophyll a content were carried out in order to evaluate the changes in crust biomass following dew. Also, we determined the activity of photosystem II(PSII) within the crust in the laboratory by simulating the desiccation/rehydration process due to dew. Results showed that the average daily dew amount as measured by the cloth-plate method (CPM) was 0.154 mm during fifty-three days and that the crust biomass fluctuated from initial inoculation of 4.3 mu g Chlorophyll a cm(-2) sand to 5.8-7.3 mu g Chlorophyll a cm(-2) crust when dew acted as the sole water source, and reached a peak value of approximately 8.2 mu g Chlorophyll a cm(-2) crust owing to rainfalls. It indicated that there was a highly significant correlation between dew amounts and crust moistures (r = 0.897 or r = 0.882, all P < 0.0001), but not a significant correlation between dew and the biomass (r = 0.246 or r = 0.257, all P > 0.05), and thus concluded that dew might only play a relatively limited role in regulating the crust biomass. Correspondingly, we found that rains significantly facilitated biomass increase of the cyanobacterial crust. Results from the simulative experiment upon rehydration showed that approximately 80% of PSII activity could be achieved within about 50 min after rehydration in the dark and at 5 degrees C, and only about 20% of the activity was light-temperature dependent. This might mean that dew was crucial for cyanobacterial crust to rapidly activate photosynthetic activity during desiccation and rehydration despite low temperatures and weak light before dawn. It also showed in this study that the cyanobacterial crusts could receive and retain more dew than sand, which depended on microclimatic characteristics and soil properties of the crusts. It may be necessary for us to fully understanding the influence of dew on regulating the growth and activity of cyanobacterial crust, and to soundly evaluate the crust's potential application in fighting desertification because of the available water due to dew. (C) 2009 Published by Elsevier Ltd.

AN EXPERIMENTAL-STUDY ON MEMBRANE DISTILLATION FOR TREATMENT OF GINSENG DEW AND GINSENG WASHING WATER

Membrane distillation is a new membrane separation process which has been developed in the last few years. When a piece of microporous hydrophobic membrane separates two kinds of aqueous solutions different in temperature, the solutions cannot transport through the pores of membrane in any directions because of the hydrophobicity of membrane. However, vapor can readily penetrate through the

The Body and the Parent-Daughter Bond : Negotiating Haitian Filial Relationships in Edwidge Danticat’s Breath, Eyes, Memory and The Dew Breaker

The Body and the Parent-Daughter Bond: Negotiating Filial Relationships in Edwidge Danticat’s Breath, Eyes, Memory and The Dew Breaker est une étude sur les différentes façons dont le corps déséquilibré, torturé et traumatisé influence la relation parent-fille. Cette thèse examine l’impact du pouvoir et de la violence sur le corps aussi bien des parents que celui des filles et les différentes manières dont ces corps deviennent déséquilibrés. Cette thèse porte sur la construction et la négociation de chacune des conditions de parents et de filles sous l’angle du corps sexué traumatisé. Le premier chapitre traite la littérature précédemment écrite sur le corps en premier lieu, et sur les liens de filiation dans les deux œuvres en second lieu. J'ai introduit ma contribution au domaine et les différents aspects de la relation parent-fille qui ne sont pas pris en considération et que ma thèse essaye de démontrer. Ce chapitre contextualise ces deux œuvres pendant l’ère de la dictature des deux Duvaliers, père et fils, en exposant et discutant l’impacte néfaste de cette dictature sur les familles. Ce chapitre conceptualise et définit le corps, qui est une construction culturelle et un site d'interaction entre le pouvoir et la violence, par rapport aux relations filiales. Dans le deuxième chapitre, l'accent est mis sur la relation de Martine et Sophie par rapport à la pratique rituelle du test de la virginité. Dans ce chapitre, j’ai soulevé des questions sur le pouvoir de Martine de discipliner et contrôler l’attitude et le corps de Sophie et la manière avec laquelle la fille peut réagir au contrôle et à la subjugation de sa mère. J’ai examiné le conflit intergénérationnel qui est intensifié par le désordre corporel. J’ai essayé de démontrer comment Sophie souhaite rejeter et se séparer du corps de sa mère et son incapacité à le faire. Dans le troisième chapitre, j’ai étudié la relation de M. Bienaimé avec sa fille Ka qui est perturbée à la fois par le corps de son père et l’identité antérieure de ce dernier en tant qu’ancien Tonton Macoute. La question soulevée dans ce chapitre concerne le corps du père comme un agent de violence politique et comme une source d’inspiration artistique pour sa fille. L'identification de Ka avec et plus tard sa séparation du corps de son père est au cœur de mon étude, car c’est ce corps là qui modifie cette relation filiale particulière, qui résulte en un traumatisme transgénérationnel. Mots-clés: corps, relation parent-fille, pouvoir, violence, Edwidge Danticat

Feedback dew-point sensor utilising optimally cut plastic optical fibres

A plastic optical fibre reflectance sensor that makes full use of the critical angle of the fibres is implemented to monitor dew formation on a Peltier-cooled reflector surface. The optical configuration permits isolation of optoelectronic components from the sensing head and better light coupling between the reflector and the detecting fibre, giving a better signal of the onset of dew formation on the reflector. Continuous monitoring of the rate of change in reflectance as well as the absolute reflectance signals, the use of a novel polymethyl-methacrylate-coated hydrophobic film reflector on the Peltier element and the application of feedback around the point of dew formation, further reduces the possibility of contamination of the sensor head. Under closed-loop operation, the sensor is capable of cycling around the point of dew formation at a frequency of 2.5 Hz.

Dew and mildew : semi-detached stories from Karabad, India /

Mode of access: Internet.

The dew is sparkling = Es blinkt der Thau /

First line of text: Each leaf doth sparkle with dew-drops of night.

Psychrometric tables for obtaining the vapor pressure, relative humidity, and temperature of the dew-point : from readings of the wet and dry bulb thermometers /

At head of title: U.S. Dept. of Agriculture, Weather Bureau.

Dew-drops of the nineteenth century : gathered and preserved in their brightness and purity /

Reissue of the 1846 ed. cf. Faxon.