Colour display for Culgoora solar radio spectrograph

A real-time colour display of the Culgoora acousto-optical radio spectrograph is described and illustrated.     

The relationship of the boundary layer of the magnetosphere to IPRP events

A model is proposed in which a mixture of hot solar wind and cold atmospheric plasma flowing in the dayside equatorial boundary layer towards the dawn-dusk plane generates hydromagnetic waves near the frequency $\text{ω = ω}{}_{\mathrm{Bi}}\text{¦1 ? T}{}_{\mathrm{\parallel }}\text{¦T}{}_{\mathrm{\perp }}\text{¦}$ where ω_Bi is the ion gyrofrequency and T_∥, T_⊥ are the temperatures of the solar wind plasma, parallel and perpendicular respectively to the magnetic field B. The model accounts for the properties of IPRP events, i.e. intervals of geomagnetic pulsations of periods rising on average from about 2 s to about 7 s over an interval of about 5 min. The diagnostic potential of this phenomenon for study of the boundary layer is indicated.     

Transient thermospheric heating and movement caused by an auroral electric field

Two closed form solutions for the velocity distribution of the upper thermosphere were found using magnetohydrodynamic formalism. One corresponds to a constant altitude, is timedependent, and has non-moving boundaries. This case asympotically approaches the steady solution obtained by Cole (1971). The other solution corresponds to a time- and altitude-dependence case with free boundaries. Solutions of electrodynamic (joule) and viscous heating for both cases are given. Some numerical results corresponding to the latter case are presented. It is clearly demonstrated that joule heating is dominant within the electric field region, and that viscous heating becomes important in the neighbourhood of the electric field region. It is also shown that the induced movement extends beyond the electric field region as far as four times the original width of the electric field region.     

Modelling the Extinction Properties of Galaxies

Recently (Granato, Lacey, Silva et al., 2000, astro-ph/0001308)we have combined our spectrophotometric galaxy evolution code which includes dust reprocessing (GRASIL, Silva et al., 1998) with semi-analytical galaxy formation models (GALFORM, Cole et al. 1999). One of the most characteristic features of the former is that the dust is divided in two main phases: molecular cloud complexes, where stars are assumed to be born, and the diffuse interstellar medium. As a consequence, stellar populations of different ages have different geometrical relationships with the two phases, which is essential in understanding several observed properties of galaxies, in particular those undergoing major episodes of star formation at any redshift. Indeed, our merged GRASIL+GALFORM model reproduces fairly well the SEDs of normal spirals and starbursts from the far-UV to the sub-mm and their internal extinction properties. In particular in the model the observed starburst attenuation law (Calzetti, 1999) is accounted for as an effect of geometry of stars and dust, and has nothing to do with the optical properties of dust grains.     

Social Mix and the `Balanced Community' in British housing policy – a tale of two epochs

In Britain, concepts of `social mix' and the `balanced community' provide an example of how policy discourses have adapted to changing conceptions of the role of the state in public provision, forms of social division and inequality, and housing market transformations. The recent development of a policy agenda by the Labour government in Britain devised to promote more socially balanced neighbourhoods is not new, and its lineage may be traced back to the origins of housing and urban policy. However, the manner in which this objective has been framed and the intervention it has provoked have varied considerably over time. One is struck more by the episodic and discontinuous nature of the application of mix and balance in British policy than any sense of a coherent set of strategies pursued through changing times. This paper contrasts the place of social mix and balance in the discourses of the immediate post-war period in Britain with the renewed emphasis on such ideas in the policies of the New Labour government elected in 1997. In the first period, the claims of social mix were infused with the language of national reconstruction and the post-war settlement and the development of universal state provision. More recently, interest in social balance has arisen partly as a response to increased management difficulties and the process of `residualisation' in social housing and partly in response to new concepts of the underclass, social exclusion and social capital. The promotion of social mix and balance in contemporary policy has been shaped by notions of the underclass, social exclusion and the development of social capital in poorer communities. Policy intervention is overtly premised on the assumption that more mixed communities will promote more positive social interaction for residents, despite the lack of evidence for this claim. In practice, much of the discourse has now taken on a stronger sense of discipline and control in order to manage social housing estates. The meaning of social balance remains confused, however, and the achievement of this objective through policy intervention is likely to remain fraught with problems.     

Fifty-eight years and counting of watershed science at the Caspar Creek Experimental Watersheds in northern California

The Caspar Creek Experimental Watersheds are the site of a long-term paired watershed study in the northern Coast Ranges of California. The watersheds are predominately forested with coast redwood and Douglas-fir. Old-growth forest was logged between 1860 and 1904. Two harvesting experiments have been completed since then and a third experiment is currently underway. Caspar Creek data are split into three phases corresponding to three experiments: Phase 1 (1962–1985) reports on a selection harvest (1971–1973) and initial recovery in the South Fork watershed; Phase 2 (1985–2017) includes clearcut harvesting of ~50% of the North Fork watershed (1985–1992) and recovery; and Phase 3 (2017 onward) corresponds to a second selection harvest in the South Fork watershed with a range of subwatershed harvest intensities (2017–2019) and recovery. All three experiments included harvest-related road-building and relied primarily on measurements of streamflow and sediment delivery from both treated and reference watersheds. Major findings include modest increases in post-harvest peak flows and cumulative flow volumes, post-harvest low flows that initially increased and then decreased 12 to 15 years after harvesting, and the consequences of different yarding techniques and road design on sediment yields. Some of the data for Phase 1 and Phase 2 are available in a USDA Forest Service online archive. The archived data include precipitation, streamflow, suspended sediment concentrations, turbidity, accumulated weir pond sediment volumes, bedload transport rates, water stable isotope data, and geospatial data. Archiving activities are ongoing. Phase 3 data are currently being collected and will be archived after a post-harvest monitoring period.     

Climate influences on water and sediment properties of Genovesa Crater Lake,Galápagos

Genovesa Crater Lake is a remote, hypersaline lake in the northern Galápagos archipelago that contains a finely laminated sediment record. This sediment record has the potential to provide a high-resolution history of past climate variability in the eastern tropical Pacific. Here we present modern climate, lake, and sediment observations from 2009 to 2012 to explore how local climate variability influences Genovesa Crater Lake and its sediments. Surface lake temperature is strongly linked to air temperature and is highly seasonal. Temperature stratification is strongest during the warm season, whereas temperature becomes more uniform through the water column in the cool season. Deeper and earlier mixing occurred during the 2010 La Niña, which subsequently delayed 2011 cool season mixing and maximum warm season surface temperatures in 2011 and 2012. Lake salinity changes are influenced by precipitation, evaporation and persistent seawater influx. The largest declines in subsurface salinity follow months after the rainy season, when temperatures cool and fresher surface water from the previous warm/wet season mixes into the subsurface. Between 2009 and 2012, more calcium carbonate precipitated during a period of higher salinity. The period of highest calcium carbonate abundance measured in sediment records that span the late nineteenth to twentieth century coincides with the failure of two consecutive rainy seasons in 1988 and 1989 as well as the coldest monthly sea surface temperature measured at Puerto Ayora in 1989. More calcium carbonate-rich laminae from AD 1550 ± 70 to 1675 ± 90 may indicate a greater frequency of prolonged droughts or cooler temperatures, although enhanced productivity may also modulate carbonate precipitation. More Ca-rich laminae in Genovesa coincide with dry conditions inferred from other Galápagos sediment proxies, as well as prolonged dry and cool conditions inferred from reconstructions of the Southern Oscillation Index and NINO3 sea surface temperatures.     

Modelling Dust in Galactic SEDs: Application to Semi-Analytical Galaxy Formation Models

We present the basic features and preliminary results of the interface between our spectrophotometric model GRASIL (which calculates galactic SEDs from the UV to the submm with a detailed computation of dust extinction and thermal reemission) with the semi-analytical galaxy formation model GALFORM (which computes galaxy formation and evolution in the hierarchical scenario, providing the star formation history as an input to our model). With these two models we are able to synthesize simulated samples of a few thousand galaxies for statistical studies of galaxy properties to investigate galaxy formation and evolution. There is good agreement with the available SED and luminosity function data. This revised version was published online in July 2006 with corrections to the Cover Date.