Studies on the moulting hormones of the desert locust schistocerca gregaria

A systematic investigation of extracts of late 5th instar nymphs of the desert locust Schistocerca gregaria has been carried out to detect and isolate moult-inducing substances. Moulting activity was detected by bioassay using the isolated abdomens of 4th instar nymphs as the test objects. At least three substances with moulting activity have been detected in whole locusts, and one has been isolated and identified as the known arthropod moulting hormone, 20-hydroxyecdysone. The other two active substances have been obtained as partially purified extracts. No ecdysone has been detected in any of the locust extracts examined. A gas-liquid 'chromatographic method has been developed for the determination of steroid hormones of the ecdysone type in biological materials. Model steroids were used to establish the conditions for the preparation and gas liquid chomatography of trimethylsilyl-methoxime derivatives of ecdysone and 20-hydroxyecdysone, and derivatives of the ecdysones were identified by mass spectrometry. The gas-liquid chromatography and the mass spectra of derivatives of the model compounds and the ecdysones are discussed. The gas-liquid chromatographic method has been applied to the examination of extracts from whole nymphs and various tissues for 20-hydroxyecdysone. This hormone was first detected and determined in purified extracts from whole locusts by gas-liquid chromatography, and has subsequently been determined in nymphs at daily intervals from day eight of the 4th instar to day three of adult development by this method. The titre was a maximum on the days of ecdysis, a minimum in the middle of the 5th instar, and fell to a low level following the emergence of the adult. Prothoracic glands isolated from late 5th ins tar nymphs have been shown, by bioassay, to contain at least two moult-inducing substances which are similar to the two unidentified active substances from whole nymphs. It is suggested that the two active components from glands are the same as those found in whole locusts, and that they are produced in the prothoracic gland. No 20-hydroxyecdysone was detected in extracts from prothoracic glands, and it is considered unlikely that this hormone is produced in the gland. Blood extracts from 5th instar locusts have been found to contain only a small proportion of the moult-inducing substances present in whole nymphs, and no 20-hydroxyecdysone could be detected. This hormone was also undetected in oenocyte bearing abdominal tissues, but as the proportion of oenocytes in the tissue was very low, this could not be used as a guide to the 20-hydroxyecdysone content of the oenocytes

Characteristics of direct human impacts on the rivers Karun and Dez in lowland south-west Iran and their interactions with earth surface movements

Two of the primary external factors influencing the variability of major river systems, over river reach scales, are human activities and tectonics. Based on the rivers Karun and Dez in south-west Iran, this paper presents an analysis of the geomorphological responses of these major rivers to ancient human modifications and tectonics. Direct human modifications can be distinguished by both modern constructions and ancient remnants of former constructions that can leave a subtle legacy in a suite of river characteristics. For example, the ruins of major dams are characterised by a legacy of channel widening to 100's up to c. 1000 m within upstream zones that can stretch to channel distances of many kilometres upstream of former dam sites, whilst the legacy of major, ancient, anthropogenic river channel straightening can also be distinguished by very low channel sinuosities over long lengths of the river course. Tectonic movements in the region are mainly associated with young and emerging folds with NW–SE and N–S trends and with a long structural lineament oriented E–W. These earth surface movements can be shown to interact with both modern and ancient human impacts over similar timescales, with the types of modification and earth surface motion being distinguishable. This paper examines the geomorphological evidence and outlines the processes involved in the evolution of these interactions through time. The analysis shows how interactions between earth surface movements and major dams are slight, especially after ancient dam collapse. By contrast, interactions between earth surface movements and major anthropogenic river channel straightening are shown to be a key factor in the persistence of long, near-straight river courses. Additionally, it is suggested that artificial river development, with very limited river channel lateral migration, may promote incision across an active fold at unusually long distances from the fold “core” and may promote markedly increased sinuosity across a structural lineament

Bestsellers in the British book industry 1998-2005

Bestsellers in the British book industry 1998-200

How Sustainable Are North American Wood Supplies?

This paper analyzes the current wood supply estimates for North America. The result of the analysis casts doubts whether the North American supplies are sustainable. It is obvious that current estimates do not consider many of the aspects of sustainable forest management but are based on a concept of the availability of timber. It can be concluded that there is a lack of consistent national projections in both the USA and Canada. The North American analyses do not take into account that the wood supply issue is driven by the political economy and not only by the market economy. North America has a lot to gain if future analyses of the supply would be carried out based on a political economic concept

Introduction: symbiosis as a living evolving critique

Different species, interacting in a symbiotic fashion, living together over a prolonged period of time, eventually co-evolving into new species: this vision of the biological phenomenon of symbiosis has created a strong impression—both of symbiosis as a metaphor and a material reality—of species in an intimate relationship together, cooperating in spite of differences, of becoming something else and transgressing boundaries. This idea has turned the concept of symbiosis, in its many guises and definitions, into a breeding ground for a posthuman, biologically and ecologically informed critique. Less focused on the biological process of symbiosis as such, our focus in Symbiosis: Ecologies, Assemblages and Evolution is more on how symbiosis can be used as a means to argue for an alternative worldview and even a better world...

Research in Home-Care Telemedicine: Challenges in Patient Recruitment

This study reports challenges in recruiting patients for a randomized controlled trial of homecare telemedicine. Descriptive statistics on patient eligibility for home-care telemedicine services and patient refusals for participation are provided. Frequency counts of reasons for study exclusion and participant refusal and Chi-square tests to compare race and age-related differences are given. Of 302 home-care patients reviewed, 197 (65.2%) did not meet inclusion criteria. The most common reasons for study exclusion were patients either needing 3 skilled nurse visits per week (n = 46, 23.4%). Of the eligible patients (n = 105), 79 persons (75.2%) refused participation. The most common reasons for refusals were lack of perceived addition benefit of telemedicine (n = 27, 34.2%), and that routine health care was sufficient (n = 23, 29.1%). Higher than expected proportions of patients did not meet chosen eligibility criteria or refused to participate. These results should be helpful in designing home-care telemedicine programs and clinical trials.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63390/1/tmj.2004.10.155.pd

Control Societies

This is a re-working of the video ‘Deleuze’s “Postscript on the Societies of Control”’, which was the second episode of Liquid Theory TV, a series of Internet Protocol Television (IPTV) programmes experimenting with new ways of acting as a ‘public intellectual’ in the current media environment. ‘Deleuze’s “Postscript on the Societies of Control”’ first appeared in Culture Machine 11, 2010. It is accompanied by an introductory essay: http://www.culturemachine.net/index.php/cm/article/view/384/40

Are models of catalytic removal of O_3 by HO_x accurate? Constraints from in situ measurements of the OH to HO_2 ratio

Measurements of the ratio OH/HO_2, NO, O_3, ClO, and BrO were obtained at altitudes from 15–20 km and latitudes from 15–60°N. A method is presented for interpreting these simultaneous in situ observations that constrains the rates of chemical transformations that 1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO_2 and 2) control the abundance of HO_2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO_2 is complete and accurate and that the potential effects of “missing chemistry” are strictly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO_2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd nitrogen in the lower stratosphere