Portals to Learning: Threshold Concepts in Art History Teaching and Learning

Threshold concepts are conceived of as portals to learning that open previously inaccessible ways of thinking. They encompass specific ideas within a discipline that must be mastered before the learner can progress. The process of identifying threshold concepts can reveal hidden or unacknowledged fundamental disciplinary beliefs and epistemology. Integrating a threshold concepts framework into the scholarship of teaching and learning in art history (SoTL-AH) can help faculty diagnose and anticipate when students are likely to encounter troublesome knowledge within an art history course. Distinguishing these thresholds can aid instructors in designing courses that prepare for specific stages that present conceptual or affective difficulty and turn those into transformative experiences that promote reconstituted and integrated knowledge. Threshold concepts can also be applied more broadly to benefit curriculum design, assessment, and the profession. This paper explains threshold concepts and bottlenecks, describes the benefits of using threshold concepts, identifies potential limitations in utilizing them in the design of teaching strategies, and proposes some preliminary threshold concepts in art history

Intracranial Stents Being Modeled as a Porous Medium: Flow Simulation in Stented Cerebral Aneurysms

Intracranial aneurysms may be treated by flow diverters, alternatively to stents and coils combination. Numerical simulation allows the assessment of the complex nature of aneurismal flow. Endovascular devices present a rather dense and fine strut network, increasing the complexity of the meshing. We propose an alternative strategy, which is based on the modeling of the device as a porous medium. Two patient-specific aneurysm data sets were reconstructed using conventional clinical setups. The aneurysms selection was done so that intra-aneurismal flow was shear driven in one and inertia driven in the other. Stents and their porous medium analog were positioned at the aneurysm neck. Physiological flow and standard boundary conditions were applied. The comparison between both approaches was done by analyzing the velocity, vorticity, and shear rate magnitudes inside the aneurysm as well as the wall shear stress (WSS) at the aneurysm surface. Simulations without device were also computed. The average flow reduction reaches 76 and 41% for the shear and inertia driven flow models, respectively. When comparing the two approaches, results show a remarkable similarity in the flow patterns and magnitude. WSS, iso-velocity surfaces and velocity on a trans-sectional plane are in fairly good agreement. The root mean squared error on the investigated parameters reaches 20% for aneurysm velocity, 30.6% for aneurysm shear rate, and 47.4% for aneurysm vorticity. It reaches 20.6% for WSS computed on the aneurysm surface. The advantages of this approach reside in its facility to implement and in the gain in computational time. Results predicted by the porous medium approach compare well with the real stent geometry model and allow predicting the main effects of the device on intra-aneurismal flow, facilitating thus the analysi

De Novo Duplication in the CHD7 Gene Associated With Severe CHARGE Syndrome.

CHARGE syndrome is an autosomal dominant developmental disorder associated with a constellation of traits involving almost every organ and sensory system, in particular congenital anomalies, including choanal atresia and malformations of the heart, inner ear, and retina. Variants in CHD7 have been shown to cause CHARGE syndrome. Here, we report the identification of a novel de novo p.Asp2119_Pro2120ins6 duplication variant in a conserved region of CHD7 in a severely affected boy presenting with 3 and 5 of the CHARGE cardinal major and minor signs, respectively, combined with congenital umbilical hernia, congenital hernia at the linea alba, mildly hypoplastic inferior vermis, slight dilatation of the lateral ventricles, prominent metopic ridge, and hypoglycemic episodes

Sphingolipids are involved in insect egg-induced cell death in Arabidopsis.

In Brassicaceae, hypersensitive-like programmed cell death (HR-like) is a central component of direct defenses triggered against eggs of the large white butterfly (Pieris brassicae). The signaling pathway leading to HR-like in Arabidopsis (Arabidopsis thaliana) is mainly dependent on salicylic acid (SA) accumulation, but downstream components are unclear. Here, we found that treatment with P. brassicae egg extract (EE) triggered changes in expression of sphingolipid metabolism genes in Arabidopsis and black mustard (Brassica nigra). Disruption of ceramide (Cer) synthase activity led to a significant decrease of EE-induced HR-like whereas SA signaling and reactive oxygen species levels were unchanged, suggesting that Cer are downstream activators of HR-like. Sphingolipid quantifications showed that Cer with C16:0 side chains accumulated in both plant species and this response was largely unchanged in the SA-induction deficient2 (sid2-1) mutant. Finally, we provide genetic evidence that the modification of fatty acyl chains of sphingolipids modulates HR-like. Altogether, these results show that sphingolipids play a key and specific role during insect egg-triggered HR-like

Studies of YBCO Strip Lines under Voltage Pulses: Optimisation of the Design of Fault Current Limiters

We present experimental results on the behaviour of a superconducting YBCO/Au meander of length L submitted to short circuit tests with constant voltage pulses. The meander, at the beginning of the short-circuit, is divided in two regions; one, with a length L1 proportional to the applied voltage, which first switches into a highly dissipative state (HDS) while the rest remains superconducting. Then the rest of the meander will progressively switch into the normal state due to the propagation of this HDS (few m/s) from both ends. The part L1 has to initially support a power density proportional to r.Jp^2 (r is the resistivity of the bilayer and Jp the peak current density). To avoid local excessive dissipation of power and over heating on one part of the wafer in the initial period, we have developed a novel design in order to distribute the dissipating section of the meander into many separated small dissipative zones. Furthermore the apparent propagation velocity of these dissipative zones is increased by the number of propagation fronts. We will show results obtained on 3kW (300V, 10A) FCL on a 2" wafer which confirm the benefits of this new design.Comment: 4 pages, 6 figures; presented at the Applied Superconductivity Conference in Houston, TX (August 2002); to be published in IEEE Trans. On Appl. Supercon

Ground state cooling, quantum state engineering and study of decoherence of ions in Paul traps

We investigate single ions of $^{40}Ca^+$ in Paul traps for quantum information processing. Superpositions of the S$_{1/2}$ electronic ground state and the metastable D$_{5/2}$ state are used to implement a qubit. Laser light on the S$_{1/2} \leftrightarrow$ D$_{5/2}$ transition is used for the manipulation of the ion's quantum state. We apply sideband cooling to the ion and reach the ground state of vibration with up to 99.9% probability. Starting from this Fock state $|n=0>$, we demonstrate coherent quantum state manipulation. A large number of Rabi oscillations and a ms-coherence time is observed. Motional heating is measured to be as low as one vibrational quantum in 190 ms. We also report on ground state cooling of two ions.Comment: 12 pages, 6 figures. submitted to Journal of Modern Optics, Special Issue on Quantum Optics: Kuehtai 200

The Measurement Bench for the LHC Spool Corrector Magnets in Industry

The LHC accelerator will be equipped with more than 3500 superconducting spool corrector magnets. CERN has awarded the contract for the series production and testing of these corrector magnets to industry. Magnetic field measurements are done at the factory. Dedicated magnetic measurement benches have been built to test these corrector magnets in the resistive state at room temperature. The benches allow to measure the strength of the main field, normal and skew harmonics, the magnetic axis position and orientation of the main field with respect to the mechanical reference points of the magnet. This paper presents the objectives, a description and the performances obtained with the benches during first measurements at industry

Vision and Foraging in Cormorants: More like Herons than Hawks?

Background Great cormorants (Phalacrocorax carbo L.) show the highest known foraging yield for a marine predator and they are often perceived to be in conflict with human economic interests. They are generally regarded as visually-guided, pursuit-dive foragers, so it would be expected that cormorants have excellent vision much like aerial predators, such as hawks which detect and pursue prey from a distance. Indeed cormorant eyes appear to show some specific adaptations to the amphibious life style. They are reported to have a highly pliable lens and powerful intraocular muscles which are thought to accommodate for the loss of corneal refractive power that accompanies immersion and ensures a well focussed image on the retina. However, nothing is known of the visual performance of these birds and how this might influence their prey capture technique. Methodology/Principal Findings We measured the aquatic visual acuity of great cormorants under a range of viewing conditions (illuminance, target contrast, viewing distance) and found it to be unexpectedly poor. Cormorant visual acuity under a range of viewing conditions is in fact comparable to unaided humans under water, and very inferior to that of aerial predators. We present a prey detectability model based upon the known acuity of cormorants at different illuminances, target contrasts and viewing distances. This shows that cormorants are able to detect individual prey only at close range (less than 1 m). Conclusions/Significance We conclude that cormorants are not the aquatic equivalent of hawks. Their efficient hunting involves the use of specialised foraging techniques which employ brief short-distance pursuit and/or rapid neck extension to capture prey that is visually detected or flushed only at short range. This technique appears to be driven proximately by the cormorant's limited visual capacities, and is analogous to the foraging techniques employed by herons