BUILDING ON TRANSIENCE: TOLERANCE AND THE SUBJECTIVE DIMENSIONS OF TECHNOLOGY

Technology acquires a provocative charge in different ways, one arising from observations of ‘transience’ in the built environment, particularly of the life and performance of buildings over time, their conception and construction, use and performance, inevitable failure or decay. Technological systems can be particularly thought provoking when human expectations and actions are implicated in the performance of buildings - which, of course, is always. This paper discusses how building technology (its conception, operation and valuation) is mediated by an ethical imperative aimed at managing change and the uncertainties it poses and from which an understanding of identity, character and values may be derived. The concept of operational ‘tolerance’ draws our attention to the capacity of building technologies to articulate change and perform according to varied physical and aesthetic expectations. Expectations might be said to include those for a certain kind of structural soundness and integrity or visual clarity. A failure to fulfil these serves to draw our attention yet further to particular environmental and even social circumstances which characterise, inhibit or enhance the operation of architectural medium – like unstable soils, pervious or defective building materials, poor workmanship or even extremes of weather and neglect. The concept of tolerance is related to the governance and normalisation of habitable space in modern times though has precursors in other times and varied modes of construction. Here it is cast as a useful analytical tool for understanding transience and the built environment in terms of technology and for describing the patterns of sensibility and self-awareness arising from an experience of technological systems

A New Halimeda (Chlorophyceae, Codiaceae) from the Philippines

Halimeda batanensis is described as a new species from Batan Island in the Philippines, and compared with similar species

Notes On The Genus Anabaenopsis

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142235/1/ajb209664.pd

The effect of intervertebral cartilage on neutral posture and range of motion in the necks of sauropod dinosaurs

The necks of sauropod dinosaurs were a key factor in their evolution. The habitual posture and range of motion of these necks has been controversial, and computer-aided studies have argued for an obligatory sub-horizontal pose. However, such studies are compromised by their failure to take into account the important role of intervertebral cartilage. This cartilage takes very different forms in different animals. Mammals and crocodilians have intervertebral discs, while birds have synovial joints in their necks. The form and thickness of cartilage varies significantly even among closely related taxa. We cannot yet tell whether the neck joints of sauropods more closely resembled those of birds or mammals. Inspection of CT scans showed cartilage:bone ratios of 4.5% for Sauroposeidon and about 20% and 15% for two juvenile Apatosaurus individuals. In extant animals, this ratio varied from 2.59% for the rhea to 24% for a juvenile giraffe. It is not yet possible to disentangle ontogenetic and taxonomic signals, but mammal cartilage is generally three times as thick as that of birds. Our most detailed work, on a turkey, yielded a cartilage:bone ratio of 4.56%. Articular cartilage also added 11% to the length of the turkey's zygapophyseal facets. Simple image manipulation suggests that incorporating 4.56% of neck cartilage into an intervertebral joint of a turkey raises neutral posture by 15°. If this were also true of sauropods, the true neutral pose of the neck would be much higher than has been depicted. An additional 11% of zygapophyseal facet length translates to 11% more range of motion at each joint. More precise quantitative results must await detailed modelling. In summary, including cartilage in our models of sauropod necks shows that they were longer, more elevated and more flexible than previously recognised

Universal quantum control of two-electron spin quantum bits using dynamic nuclear polarization

One fundamental requirement for quantum computation is to perform universal manipulations of quantum bits at rates much faster than the qubit's rate of decoherence. Recently, fast gate operations have been demonstrated in logical spin qubits composed of two electron spins where the rapid exchange of the two electrons permits electrically controllable rotations around one axis of the qubit. However, universal control of the qubit requires arbitrary rotations around at least two axes. Here we show that by subjecting each electron spin to a magnetic field of different magnitude we achieve full quantum control of the two-electron logical spin qubit with nanosecond operation times. Using a single device, a magnetic field gradient of several hundred milliTesla is generated and sustained using dynamic nuclear polarization of the underlying Ga and As nuclei. Universal control of the two-electron qubit is then demonstrated using quantum state tomography. The presented technique provides the basis for single and potentially multiple qubit operations with gate times that approach the threshold required for quantum error correction.Comment: 11 pages, 4 figures. Supplementary Material included as ancillary fil

Observation of anomalous decoherence effect in a quantum bath at room temperature

Decoherence of quantum objects is critical to modern quantum sciences and technologies. It is generally believed that stronger noises cause faster decoherence. Strikingly, recent theoretical research discovers the opposite case for spins in quantum baths. Here we report experimental observation of the anomalous decoherence effect for the electron spin-1 of a nitrogen-vacancy centre in high-purity diamond at room temperature. We demonstrate that under dynamical decoupling, the double-transition can have longer coherence time than the single-transition, even though the former couples to the nuclear spin bath as twice strongly as the latter does. The excellent agreement between the experimental and the theoretical results confirms the controllability of the weakly coupled nuclear spins in the bath, which is useful in quantum information processing and quantum metrology.Comment: 22 pages, related paper at http://arxiv.org/abs/1102.557