The glacial cycles and cosmic rays

The cause of the glacial cycles remains a mystery. The origin is widely accepted to be astronomical since paleoclimatic archives contain strong spectral components that match the frequencies of Earth's orbital modulation. Milankovitch insolation theory contains similar frequencies and has become established as the standard model of the glacial cycles. However, high precision paleoclimatic data have revealed serious discrepancies with the Milankovitch model that fundamentally challenge its validity and re-open the question of what causes the glacial cycles. We propose here that the ice ages are initially driven not by insolation cycles but by cosmic ray changes, probably through their effect on clouds. This conclusion is based on a wide range of evidence, including results presented here on speleothem growth in caves in Austria and Oman, and on a record of cosmic ray flux over the past 220 kyr obtained from the 10Be composition of deep-ocean sediments

A network-indexbased version of TOPMODEL for use with high-resolution digital topographic data

This paper describes the preliminary development of a network index approach to modify and to extend the classic TOPMODEL. Application of the basic Beven and Kirkby (1979) form of TOPMODEL to high resolution (2.0 m) laser altimetric data (based upon the U.K. Environment Agency’s Light Detection and Ranging (LIDAR) system) to a 13.8 km(2) catchment in an upland environment identified large areas of saturated areas that remained unconnected from the drainage network even during an extreme flood event. This is shown to be a particular problem with using high resolution topographic data especially over large spatial scales. To deal with the hydrological consequences of disconnected areas, we present a simple network index modification in which saturated areas only connect when the topographic index is sufficient for there to be zero or negative saturation deficits along a complete flow path. This is combined with an enhanced method for dealing with the problem of pits and hollows which is shown to become more acute with higher resolution topographic data. The paper concludes by noting the implications of the research as presented for both methodological and substantive research that is currently under way

E.P.R. lineshapes in maser materials

Using a 35 Gc/sec spectrometer, E.P.R. linewidths have been measured in a number of synthetic ruby specimens grown by various means. In addition, measurements of both linewidth and relaxation time have been made on a number of specimens of calcium tungstate doped with neodymiura. Using a mathematical treatment of the second moment, the homogeneously broadened ruby line has been resolved into concentration-dependent and concentration-independent components. The observed constant nature of the former suggests that the effective concentration of paramagnetic centres is not indicative of the true chemical concentration. Analysis of the inhomogeneous ruby line results in broadening components representative of axial misorientation and strain, A moderate correlation is obtained between misorientation figures derived from x-ray and e.p.r. measurements, and a similar correlation exists between strain and spin-lattice relaxation times. There appear to be no significant differences between the various types of flame-fusion material available. Preliminary analysis suggests that the homogeneous line in calcium tungstate owes its width to processes similar to those occuring in ruby, but strain does not appear to be predominant in the inhomogeneous broadening. Relaxation times in this material exhibit concentration and orientation dependence and a temperature dependence has been fitted empirically in the Direct and Raman regions

Multi-species nucleation rates in CLOUD

In the CLOUD experiment at CERN we have been investigating the chemical species that are most important to atmospheric new particle formation. Sulphuric acid plays a key role in aerosol nucleation, but other vapours and ions can strongly enhance the formation rate. Quantifying the contribution of each species and the conditions under which each one is important is a major challenge and requires sophisticated laboratory experiments. The CLOUD chamber, a 3m stainless steel aerosol chamber exposed to a pion beam from the CERN Proton Synchrotron, can create a precisely controlled atmospheric environment over a wide range of temperatures, ionisation states and gas mixtures, while keeping contamination levels extremely low. CLOUD has studied a range of vapour species at atmospheric concentrations, including, in various combinations, sulphuric acid, ammonia, dimethylamine and alpha-pinene. The effect of ions on the nucleation rates has been measured for all species since it is of considerable interest as a possible link between galactic cosmic rays and climate[1]. This work will present an overview of the nucleation rates measured in CLOUD and compare them with atmospheric observations

Characterizing temporary hydrological regimes at a European scale

Monthly duration curves have been constructed from climate data across Europe to help address the relative frequency of ecologically critical low flow stages in temporary rivers, when flow persists only in disconnected pools in the river bed. The hydrological model is 5 based on a partitioning of precipitation to estimate water available for evapotranspiration and plant growth and for residual runoff. The duration curve for monthly flows has then been analysed to give an estimate of bankfull flow based on recurrence interval. The corresponding frequency for pools is then based on the ratio of bank full discharge to pool flow, arguing from observed ratios of cross-sectional areas at flood 10 and low flows to estimate pool flow as 0.1% of bankfull flow, and so estimate the frequency of the pool conditions that constrain survival of river-dwelling arthropods and fish. The methodology has been applied across Europe at 15 km resolution, and can equally be applied under future climatic scenarios

Investigating the intrinsic noise limit of Dayem bridge NanoSQUIDs

NanoSQUIDs made from Nb thin films have been produced with nanometre loop sizes down to 200 nm, using weak-link junctions with dimensions less than 60 nm. These composite (W/Nb) single layer thin film devices, patterned by FIB milling, show extremely good low-noise performance ∼170 nΦ0 at temperatures between 5 and 8.5 K and can operate in rather high magnetic fields (at least up to 1 T). The devices produced so far have a limited operating temperature range, typically only 1–2 K. We have the goal of achieving operation at 4.2 K, to be compatible with the best SQUID series array (SSA) preamplifier available. Using the SSA to readout the nanoSQUIDs provides us with a means of investigating the intrinsic noise of the former. In this paper we report improved white noise levels of these nanoSQUIDs, enabling potential detection of a single electronic spin flip in a 1-Hz bandwidth. At low frequencies the noise performance is already limited by SSA preamplifier noise

The view from elsewhere: perspectives on ALife Modeling

Many artificial life researchers stress the interdisciplinary character of the field. Against such a backdrop, this report reviews and discusses artificial life, as it is depicted in, and as it interfaces with, adjacent disciplines (in particular, philosophy, biology, and linguistics), and in the light of a specific historical example of interdisciplinary research (namely cybernetics) with which artificial life shares many features. This report grew out of a workshop held at the Sixth European Conference on Artificial Life in Prague and features individual contributions from the workshop's eight speakers, plus a section designed to reflect the debates that took place during the workshop's discussion sessions. The major theme that emerged during these sessions was the identity and status of artificial life as a scientific endeavor

Exercise-induced asthma in a group of South African schoolchildren during physical education classes

Objectives. The study was conducted to ascertain whether physical education teachers, using a peak flow meter, could reliably screen for exercise-induced asthma (EIA) in children during free running.Design, setting and subjects. The study was conducted using a convenience sample of male pupils between the ages of 12 and 18 years. They were tested with a peak flow meter for peak expiratory flow rate (PEFR) and with a flow-volume curve for forced expiratory flow in 1 second (FEV1) before and 10 minutes after a self-paced free running test during physical education classes. Testing was undertaken by teachers using the peak flow meter and by a medical doctor using a flow-volume curve.Results. Using a 10% decrease in flow parameters (PEFR and FEV1), teachers detected EIA in 14.9% of pupils and the doctor detected EIA in 21.7% of pupils.Conclusion. We conclude that EIA is common and that teachers using a peak flow meter can detect EIA and thus screen for it; they do, however, underestimate the true magnitude of the problem