9,161 research outputs found
Collaboration and teamwork: immersion and presence in an online learning environment
In the world of OTIS, an online Internet School for occupational therapists, students from four European countries were encouraged to work collaboratively through problem-based learning by interacting with each other in a virtual semi-immersive environment. This paper describes, often in their own words, the experience of European occupational therapy students working together across national and cultural boundaries. Collaboration and teamwork were facilitated exclusively through an online environment, since the students never met each other physically during the OTIS pilot course. The aim of the paper is to explore the observations that here was little interaction between students from different tutorial groups and virtual teamwork developed in each of the cross-cultural tutorial groups. Synchronous data from the students was captured during tutorial sessions and peer-booked meetings and analysed using the qualitative constructs of ‘immersion’, ‘presence’ and ‘reflection in learning’. The findings indicate that ‘immersion’ was experienced only to a certain extent. However, both ‘presence’ and shared presence were found by the students, within their tutorial groups, to help collaboration and teamwork. Other evidence suggests that communities of interest were established. Further study is proposed to support group work in an online learning environment. It is possible to conclude that collaborative systems can be designed, which encourage students to build trust and teamwork in a cross cultural online learning environment.</p
Perfection of materials technology for producing improved Gunn-effect devices Interim scientific report
Chemical vapor deposition of epitaxial gallium arsenid
Excitons in Electrostatic Traps
We consider in-plane electrostatic traps for indirect excitons in coupled
quantum wells, where the traps are formed by a laterally modulated gate
voltage. An intrinsic obstacle for exciton confinement in electrostatic traps
is an in-plane electric field that can lead to exciton dissociation. We propose
a design to suppress the in-plane electric field and, at the same time, to
effectively confine excitons in the electrostatic traps. We present
calculations for various classes of electrostatic traps and experimental proof
of principle for trapping of indirect excitons in electrostatic traps.Comment: 4 pages, 3 figure
Perfection of materials technology for producing improved Gunn-effect devices
Chemical vapor deposition system for improved Gunn effect devices using arsenic chloride 3 metho
Carbon dioxide release from retrogressive thaw slumps in Siberia
Abstract
Thawing of ice-rich permafrost soils in sloped terrain can lead to activation of retrogressive thaw slumps (RTSs) which make organic matter available for decomposition that has been frozen for centuries to millennia. Recent studies show that the area affected by RTSs increased in the last two decades across the pan-Arctic. Combining a model of soil carbon dynamics with remotely sensed spatial details of thaw slump area and a soil carbon database, we show that RTSs in Siberia turned a previous quasi-neutral ecosystem into a strong source of carbon dioxide of 367 ± 213 gC m-1 a-1. On a global scale, recent CO2 emissions from Siberian thaw slumps of 0.42 ± 0.22 Tg carbon per year are negligible so far. However, depending on the future evolution of permafrost thaw and hence thaw slump-affected area, such hillslope processes can transition permafrost landscapes to become a major source of additional CO2 release into the atmosphere.</jats:p
Measurement of neutron capture on Ca at thermal and thermonuclear energies
At the Karlsruhe pulsed 3.75\,MV Van de Graaff accelerator the thermonuclear
Ca(n,)Ca(8.72\,min) cross section was measured by the
fast cyclic activation technique via the 3084.5\,keV -ray line of the
Ca-decay. Samples of CaCO enriched in Ca by 77.87\,\% were
irradiated between two gold foils which served as capture standards. The
capture cross-section was measured at the neutron energies 25, 151, 176, and
218\,keV, respectively. Additionally, the thermal capture cross-section was
measured at the reactor BR1 in Mol, Belgium, via the prompt and decay
-ray lines using the same target material. The
Ca(n,)Ca cross-section in the thermonuclear and thermal
energy range has been calculated using the direct-capture model combined with
folding potentials. The potential strengths are adjusted to the scattering
length and the binding energies of the final states in Ca. The small
coherent elastic cross section of Ca+n is explained through the nuclear
Ramsauer effect. Spectroscopic factors of Ca have been extracted from
the thermal capture cross-section with better accuracy than from a recent (d,p)
experiment. Within the uncertainties both results are in agreement. The
non-resonant thermal and thermonuclear experimental data for this reaction can
be reproduced using the direct-capture model. A possible interference with a
resonant contribution is discussed. The neutron spectroscopic factors of
Ca determined from shell-model calculations are compared with the values
extracted from the experimental cross sections for Ca(d,p)Ca and
Ca(n,)Ca.Comment: 15 pages (uses Revtex), 7 postscript figures (uses psfig), accepted
for publication in PRC, uuencoded tex-files and postscript-files also
available at ftp://is1.kph.tuwien.ac.at/pub/ohu/Ca.u
A nitrite microsensor for profiling environmental biofilms
A highly selective liquid membrane nitrite microsensor based on the hydrophobic ion-carrier aquocyano-cobalt(III) -hepta(2-phenylethyl)-cobrynate is described, The sensor has a tip diameter of 10 to 15 mu m. The response is log-linear in freshwater down to 1 mu M NO2- and in seawater to 10 mu M NO2-. A method is described for preparation of relatively large polyvinyl chloride (PVC)-gelled liquid membrane microsensors with a tip diameter of 5 to 15 mu m, having a hydrophilic coating on the tip, The coating and increased tip diameter resulted in more sturdy sensors, with a lower detection limit and a more stable signal than uncoated nitrite sensors with a tip diameter of 1 to 3 mu m. The coating protects the sensor membrane from detrimental direct contact with biomass and can be used for all PVC-gelled liquid membrane sensors meant for profiling microbial mats, biofilms, and sediments. Thanks to these improvements, liquid membrane sensors can now be used in complex environmental samples and in situ, e.g., in operating bioreactors. Examples of measurements in denitrifying, nitrifying, and nitrifying/denitrifying biofilms from wastewater treatment plants are shown. In all of these biofilms high nitrite concentrations were found in narrow zones of less than 1 mm
Australian local governments and affordable housing: Challenges and possibilities
© The Author(s) 2019. For an increasing proportion of Australian households, the Australian dream of home ownership is no longer an option. Neoliberal housing policy and the financialisation of housing has resulted in a housing affordability crisis. Historically, Australian housing policy has afforded only a limited role to local government. This article analyses the results of a nation-wide survey of Australian local governments’ perceptions of housing affordability in their local government area, the possibilities for their meaningful intervention, the challenges they face, the role of councillors and councils’ perceptions of what levels of government should take responsibility for housing. Almost all of the respondents from Sydney and Melbourne councils were clear that there is a housing affordability crisis in their local government area. We apply a framework analysing housing policy in the context of neoliberalism and the related financialisation of housing in order to analyse the housing affordability crisis in Sydney and Melbourne. We conclude that in order to begin resolving the housing crisis in Australia’s two largest cities there has to be an increasing role for local government, a substantial increase in the building of social and affordable housing and a rollback of policies that encourage residential property speculation. JEL Codes: R31, R21
On mercury vapor lamps and their effect on the smart-grid PLC channel
Abstract: The mercury vapor lamp is the oldest high intensity discharge technology lamp that uses an electric arc, and comes in different shapes and designs. It creates a very bright light by using an arc through vaporized mercury in a high pressure tube. This lamp can cause unwanted interference to the smart-grid network or power line communications channel when connected to the channel’s wiring system. In this paper we investigate the negative effects that the mercury vapor lamps with electric ballast have on the smart-grid PLC channel. This can have a strong and negative effect when using the smart-grid PLC network to control the automatic switching of lamps in public places. The narrowband and broadband channels are investigated where the interference level from mercury vapor lamps is significantly below the allowed maximum PLC signal levels on the band: (3 kHz – 150 kHz), and competes with Electromagnetic Compatibility (EMC) levels on the 150 kHz – 30 MHz band. The mercury vapor lamp uses an electric ballast to connect to the powerline system. This connection is explained in detail
The influence of fluorescent lamps with electronic ballast on the low voltage PLC network
The fluorescent lamps or fluorescent tubes are low pressure mercury-vapor gas-discharge lamps that use fluorescence to produce visible light. These lamps inject noise into the power-line communications channel. This can have a detrimental effect on the power-line communication system. In this paper we investigate the effects when the fluorescent lamps with electronic ballasts are seen as noise sources on the powerline channel. It is shown that in the CENELEC band: (3kHz – 150kHz) the interference level from fluorescent lamps is significantly below the allowed maximum PLC signal levels. In the band 150kHz – 30MHz however, PLC signals compete with Electromagnetic Compatibility (EMC) levels. The operational method of the electronic ballast inside the fluorescent lamp is explained
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