186 research outputs found
PROVOCATIVE AGENTS: AGENT BASE MODELLING SYSTEMS AND THE GLOBAL PRODUCTION OF ARCHITECTURE
Experimental architects are actively pursuing the use of agent based modelling as a way to
dynamically simulate behaviour in cities. These efforts appear to mirror the simulations of
climate scientists who have also developed dynamic models which are used to predict both
global and regional climate change. In climate models it is the earth as a whole, rather than the
city, which is viewed from above as a complex, dynamic and total system. In the models of cities
developed by architects and urbanists agent based software has given global cities a new and
enchanted life of their own. These modelling experiments and simulations have been theorised
in architectural discourse as providing a link between the global city and ecological systems.
The mix of biological metaphors and concepts, biomorphic forms, cybernetics and networked
geometries in agent based architecture work points to the rise and theorization of systems
approaches in 1960s architecture. The emergence of agent based software in architecture and
urbanism will be situated in relation to its use and potential in ecological informatics, climate
models, defense and manufacturing optimization. This will highlight the issues involved in
distinguishing between exploratory and exploitative technological innovations. The nature of
exploratory innovation is reflected in the desire of architects to visualise the global city as both
an organic totality and as a intelligent and complex organism
Scaling Laws and Transient Times in 3He Induced Nuclear Fission
Fission excitation functions of compound nuclei in a mass region where shell
effects are expected to be very strong are shown to scale exactly according to
the transition state prediction once these shell effects are accounted for. The
fact that no deviations from the transition state method have been observed
within the experimentally investigated excitation energy regime allows one to
assign an upper limit for the transient time of 10 zs.Comment: 7 pages, TeX type, psfig, submitted to Phys. Rev. C, also available
at http://csa5.lbl.gov/moretto/ps/he3_paper.p
Counting individual 41Ca atoms with a magneto-optical trap
Atom Trap Trace Analysis (ATTA), a novel method based upon laser trapping and
cooling, is used to count individual atoms of 41Ca present in biomedical
samples with isotopic abundance levels between 10^-8 and 10^-10. ATTA is
calibrated against Resonance Ionization Mass Spectrometry, demonstrating a good
agreement between the two methods. The present ATTA system has a counting
efficiency of 2x10^-7. Within one hour of observation time, its 3-sigma
detection limit on the isotopic abundance of 41Ca reaches 4.5x10^-10
Electron and Gamma Background in CRESST Detectors
The CRESST experiment monitors 300g CaWO_4 crystals as targets for particle
interactions in an ultra low background environment. In this paper, we analyze
the background spectra that are recorded by three detectors over many weeks of
data taking. Understanding these spectra is mandatory if one wants to further
reduce the background level, and allows us to cross-check the calibration of
the detectors. We identify a variety of sources, such as intrinsic
contaminations due to primordial radioisotopes and cosmogenic activation of the
target material. In particular, we detect a 3.6keV X-ray line from the decay of
41-Ca with an activity of (26\pm4)\mu Bq, corresponding to a ratio
41-Ca/40-Ca=(2.2\pm0.3)\times10^{-16}.Comment: 7 pages, 12 figure
Circulation of water masses in the Baltic Proper revealed through iodine isotopes
Tracer technology has been used to understand water circulation in marine systems where the tracer dose is commonly injected into the marine waters through controlled experiments, accidental releases or waste discharges. Anthropogenic discharges of I-129 have been used to trace water circulation in the Arctic and North Atlantic Ocean. Here, I-129, together with I-127, is utilized as a tracer of water pathways and circulation in the Baltic Sea through collection of seawater depth profiles. The results indicate the presence of I-129 signatures which are distinct for each water mass and provide evidence for: (1) inflow water masses through the Drogden Sill that may reach as far as the SW of the Arkona Sea, (2) a portion of North Atlantic water in the bottom of Arkona basin, (3) cyclonic upwelling which breaks through the halocline in a pattern similar to the Baltic haline conveyor belt and (4) more influx of fresher water from the Gulf of Finland and Bothnian Sea in August relative to April. These findings provide advances in labeling and understanding water pathways in the Baltic Sea.</p
The Proceedings of the Fourth International Conference of the Association of Architecture Schools of Australasia
The Proceedings of the Fourth International Conference of the Association of Architecture
Schools of Australasia.
Each paper in the Proceedings has been double refereed by members of an independent panel
of academic peers appointed by the Conference Committee. Papers were matched, where
possible, to referees in the same field and with similar interests to the authors
State of the Antarctic and Southern Ocean Climate System
This paper reviews developments in our understanding of the state of the Antarctic and Southern Ocean climate and its relation to the global climate system over the last few millennia. Climate over this and earlier periods has not been stable, as evidenced by the occurrence of abrupt changes in atmospheric circulation and temperature recorded in Antarctic ice core proxies for past climate. Two of the most prominent abrupt climate change events are characterized by intensification of the circumpolar westerlies (also known as the Southern Annular Mode) between âŒ6000 and 5000 years ago and since 1200â1000 years ago. Following the last of these is a period of major trans-Antarctic reorganization of atmospheric circulation and temperature between A.D. 1700 and 1850. The two earlier Antarctic abrupt climate change events appear linked to but predate by several centuries even more abrupt climate change in the North Atlantic, and the end of the more recent event is coincident with reorganization of atmospheric circulation in the North Pacific. Improved understanding of such events and of the associations between abrupt climate change events recorded in both hemispheres is critical to predicting the impact and timing of future abrupt climate change events potentially forced by anthropogenic changes in greenhouse gases and aerosols. Special attention is given to the climate of the past 200 years, which was recorded by a network of recently available shallow firn cores, and to that of the past 50 years, which was monitored by the continuous instrumental record. Significant regional climate changes have taken place in the Antarctic during the past 50 years. Atmospheric temperatures have increased markedly over the Antarctic Peninsula, linked to nearby ocean warming and intensification of the circumpolar westerlies. Glaciers are retreating on the peninsula, in Patagonia, on the sub-Antarctic islands, and in West Antarctica adjacent to the peninsula. The penetration of marine air masses has become more pronounced over parts of West Antarctica. Above the surface, the Antarctic troposphere has warmed during winter while the stratosphere has cooled year-round. The upper kilometer of the circumpolar Southern Ocean has warmed, Antarctic Bottom Water across a wide sector off East Antarctica has freshened, and the densest bottom water in the Weddell Sea has warmed. In contrast to these regional climate changes, over most of Antarctica, near-surface temperature and snowfall have not increased significantly during at least the past 50 years, and proxy data suggest that the atmospheric circulation over the interior has remained in a similar state for at least the past 200 years. Furthermore, the total sea ice cover around Antarctica has exhibited no significant overall change since reliable satellite monitoring began in the late 1970s, despite large but compensating regional changes. The inhomogeneity of Antarctic climate in space and time implies that recent Antarctic climate changes are due on the one hand to a combination of strong multidecadal variability and anthropogenic effects and, as demonstrated by the paleoclimate record, on the other hand to multidecadal to millennial scale and longer natural variability forced through changes in orbital insolation, greenhouse gases, solar variability, ice dynamics, and aerosols. Model projections suggest that over the 21st century the Antarctic interior will warm by 3.4° ± 1°C, and sea ice extent will decrease by âŒ30%. Ice sheet models are not yet adequate enough to answer pressing questions about the effect of projected warming on mass balance and sea level. Considering the potentially major impacts of a warming climate on Antarctica, vigorous efforts are needed to better understand all aspects of the highly coupled Antarctic climate system as well as its influence on the Earth\u27s climate and oceans
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