Observations on the influence of external factors on the duration of the embryonic development and on the molting rhythm of Cyclops vicinus. [Translation from: Oecologia 7, 342-355, 1971.]

Investigations on the control of the embryonic and post-embryonic development of arthropods have formed an intensively studied field of zoological research for a long time, Here in especially favourable cases the causal chain from the operation of external factors on the influence of physiological mechanisms, eg. of the hormone variety, is known right through to its primary influences. A comparative approach to the relevant questions was in the main only made in the case of the insects. For crustacea , investigations are available almost exclusively only for the malacostraca. This study examines the influence of the factors of temperature and photoperiod on the entire development of Cyclops vicinus. Tests were made on whether the light-darkness change serves as a regulator for a possible existing molting rhythm - a question which for the entire arthropods has been settled only very rarely. The basic material for the cultures that were examined originates from Lake Constance

Explicit representation of the implicit Colebrook–White equation

AbstractIt is shown that the Colebrook–White equation 1/λ=−2lg[2.51/Reλ+ϵ/3.71D] can be solved analytically for the friction factor λ. The solution contains two infinite sums. For given Reynolds numbers Re and relative roughnesses ϵ/D, one can create an own approximation with the required accuracy by adding a finite number of summands. The computing time of both the iterative calculation and several approximations is being compared. In all cases, the approximation is much faster than the iteration. Two examples for practical applications are given

Deutsch-russische Zusammenarbeit in der Arktis

Seit 1993 wird im Rahmen zweier vom BMBF geförderter Projekte die Laptevsee in der russischen Arktis (nicht nur) biologisch untersucht. Von 1993 - 1997 wurde das am Institut für Polarökologie angesiedelte Projekt. Deutsch - Russische Untersuchungen zur Ökologie der Randmeere der Eurasischen Arktis" mit insgesamt 1,5 Mio. DM gefördert. In einer zweiten Phase, die 199 8 begann, wurde die biologische Forschung in der Laptevsee mit veränderten Forschungsschwerpunkten als Teilprojekt in das Verbundvorhaben "System Laptevsee 2000" eingebettet. Im folgenden soll ein kurzer Uberblick über die biologischen Forschungsaktivitäten im Rahmen dieser Projekte gegeben werden

The effect of long term ageing on the autogenous welding of dissimilar austenitic stainless steels

Austenitic stainless steels are used extensively throughout power stations in high temperature applications such as superheater tubes and fuel rod guides. For these applications, welding is often required to join sections of components or pipes/tubes due to their large sizes and lengths. In this paper, samples of a cast niobium stabilised stainless steel welded to a wrought 321 stainless steel were investigated. The sections were joined together using an autogenous Tungsten Inert Gas (TIG) weld. The effects of long term ageing at 750°C for up to 4000 hours have been studied. The ageing treatments were conducted in an inert atmosphere. Compositional changes and precipitates have been investigated using SEM with EDX and EBSD analysis. Niobium dissolved completely into the weld melt however it is observed to precipitate back out during long term ageing. Titanium carbonitrides however remained intact during the welding process, creating agglomerated particles throughout the weld bead. Ageing above 100 hours causes further Nb rich MX precipitates to form, which coarsen with longer ageing times up to 4000 hours

The most creative organization in the world? The BBC, 'creativity' and managerial style

The managerial styles of two BBC directors-general, John Birt and Greg Dyke, have often been contrasted but not so far analysed from the perspective of their different views of 'creative management'. This article first addresses the orthodox reading of 'Birtism'; second, it locates Dyke's 'creative' turn in the wider context of fashionable neo-management theory and UK government creative industries policy; third, it details Dyke's drive to change the BBC's culture; and finally, it concludes with some reflections on the uncertainties inherent in managing a creative organisation

Hydroxymethanesulfonic acid in size-segregated aerosol particles at nine sites in Germany

In the course of two field campaigns, size-segregated particle samples were collected at nine sites in Germany, including traffic, urban, rural, marine and mountain sites. During the chemical characterisation of the samples some of them were found to contain an unknown substance that was later identified as hydroxymethanesulfonic acid (HMSA). HMSA is known to be formed during the reaction of S(IV) (HSO3− or SO32−) with formaldehyde in the aqueous phase. Due to its stability, HMSA can act as a reservoir species for S(IV) in the atmosphere and is therefore of interest for the understanding of atmospheric sulfur chemistry. However, no HMSA data are available for atmospheric particles from central Europe, and even on a worldwide scale data are scarce. Thus, the present study now provides a representative data set with detailed information on HMSA concentrations in size-segregated central European aerosol particles. HMSA mass concentrations in this data set were highly variable: HMSA was found in 224 out of 738 samples (30%), sometimes in high mass concentrations exceeding those of oxalic acid. On average over all 154 impactor runs, 31.5 ng m−3 HMSA was found in PM10, contributing 0.21% to the total mass. The results show that the particle diameter, the sampling location, the sampling season and the air mass origin impact the HMSA mass concentration. Highest concentrations were found in the particle fraction 0.42–1.2 μm, at urban sites, in winter and with eastern (continental) air masses, respectively. The results suggest that HMSA is formed during aging of pollution plumes. A positive correlation of HMSA with sulfate, oxalate and PM is found (R2 > 0.4). The results furthermore suggest that the fraction of HMSA in PM slightly decreases with increasing pH

Analysis of laser absorption on a rough metal surface

We have developed a simple model to estimate the cumulative absorption coefficient of an ultraviolet laser pulse impinging on a pure metal, including the effects of surface roughness whose scale is much larger than the laser wavelength λ. The multiple reflections from the rough surface may increase the absorption coefficient over a pristine, flat surface by an order of magnitude. Thus, as much as 16% (at room temperature) of the power of a 248 nm KrF excimer laser pulse may be absorbed by an aluminum target. A comparison with experimental data is given. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71289/2/APPLAB-70-6-696-1.pd