Observation of chiral heat transport in the quantum Hall regime

Heat transport in the quantum Hall regime is investigated using micron-scale heaters and thermometers positioned along the edge of a millimeter-scale two dimensional electron system (2DES). The heaters rely on localized current injection into the 2DES, while the thermometers are based on the thermoelectric effect. In the v=1 integer quantized Hall state, a thermoelectric signal appears at an edge thermometer only when it is “downstream,” in the sense of electronic edge transport, from the heater. When the distance between the heater and the thermometer is increased, the thermoelectric signal is reduced, showing that the electrons cool as they propagate along the edge

Parsing with parallelism : a spreading-activation model of inference processing during text understanding

The past decade of reseatch in Natural Language Processing has universally recognized that, since natural language input is almost always ambiguous with respect to its pragmatic implications, its syntactic parse, and even its lexical analysis (i.e., choice of correct word-sense for an ambiguous word), processing natural language input requires decisions about word meanings, syntactic structure, and pragmatic inferences. The lexical, syntactic, and pragmatic levels of inferencing are not as disparate as they have often been treated in both psychological and artificial intelligence research. In fact, these three levels of analysis interact to form a joint interpretation of text.ATLAST (A Three-level Language Analysis SysTem) is an implemented integration of human language understanding at the lexical, the syntactic, and the pragmatic levels. For psychological validity, ATLAST is based on results of experiments with human subjects. The ATLAST model uses a new architecture which was developed to incorporate three features: spreading activation memory, two-stage syntax, and parallel processing of syntax and semantics. It is also a new framework within which to interpret and tackle unsolved problems through implementation and experimentation

STRATEGIST : a program that models strategy-driven and content-driven inference behavior

In the course of understanding a text, different readers use different inference strategies to guide their choice of interpretations of the events in the text. This is in contrast to previous computer models of understanding, which all use the content-driven inference. The separate strategies are theorized to be composed of the same component inference processes, but of different rules for application of the processes. The use of different strategies occasionally results in different results of new experimental data and a working computer program, called STRATEGIST, that models both strategy-drive and content-driven inference behavior. The rules which make up two of these strategies are presented

Economic Impact Assessment: the creative sector in the Western Region

Introduction. Developments around the globe are re-defining media, arts and other related sectors as ‘creative industries’ which are being recognised for their potential impact on local and national economies. This economic impact assessment builds on previous work commissioned by the Western Development Commission and contends that artistic and cultural activities are not simple by-products of a developed economy but essential elements of economic success and sustainability. Such activities represent alternate forms of expression of human creativity that encourage lateral thinking and thus complement scientific and technological innovation. As we will see, these activities lie at the core of a number of growing sectors in the region, and contribute directly to employment growth and wealth creation2. Internationally, the case for fostering the creative economy is a convincing one. In the ten years up to 2005, the creative economy grew at twice the annual rate of the service industries and four times the rate of manufacturing in OECD countries3. In Europe, the growth of the cultural and creative sector was 12.3% higher than the growth of the overall economy from 1999 to 2003. From an economic perspective, international trade is a key component, from 2000 – 2005, trade in creative-industry products grew on average by 8.7% annually. These figures have grabbed the attention of policy makers here and abroad. This report was commissioned by the Western Development Commission (WDC) in July 2010 to consider the economic impact of the Creative Economy in the Western Region of Ireland4. It builds on previous work carried out by Oxford Economics and the WDC. That work, published as the Creative West document in early 2009 informed a great deal of debate at the regional and national level. This work attempts to add a dynamic element to what was a snapshot of the sector

Studies on the Genes for the Enzymes of the Shikimate Pathway From Pisum sativum

Aromatic compounds are synthesised via the shikimate pathway. The fungal pentafunctional arom enzyme has five shikimate pathway activities on one polypeptide chain whereas in bacteria, all seven activities are separate enzymes. In all plants, which have been examined, including Pisum sativum, the shikimate pathway enzymes are separable except for 3-dehydroquinase and shikimate dehydrogenase. These activities occur on a single bifunctional polypeptide. The genes for the shikimate pathway enzymes have been isolated from a variety of microbial sources. This thesis is concerned with attempts to isolate the genes for the shikimate pathway enzymes from P. sativum

The Art of Disruption. Creative learning and disruption in the higher education sector

In an operating environment dominated by rapid technological change, the temptation to call this disruptive is even greater. In this paper, we draw on the disruption literature and the imagery from this, to view and understand significant changes shaping the current UK higher education sector. In particular, we note the way in which the main institutions in society are changing and note the new business models that have emerged relating to fees and commercialisation in universities. We also note however, the new possibilities for universities arising from market demand for new technologies and concomitantly, new job roles in the labour market, all of which require new responses from universities. Focusing on the creative industries, where change has been marked, the ecologies have become crowded, and where incessant skill needs go hand-in-hand with changing student and worker characteristics, universities are faced with an acute pressure point. We argue here that this pressure point is such that the opportunity cost of not responding through disruption will be too great and will lead inevitably to a loss of market position. In this first in a series of think pieces, we look to challenge conventional thinking by considering what disruption might mean in the context of universities, and what sort of transformation is needed to secure universities’ provision and role in the creative economy

Reducing the Bias of Causality Measures

Measures of the direction and strength of the interdependence between two time series are evaluated and modified in order to reduce the bias in the estimation of the measures, so that they give zero values when there is no causal effect. For this, point shuffling is employed as used in the frame of surrogate data. This correction is not specific to a particular measure and it is implemented here on measures based on state space reconstruction and information measures. The performance of the causality measures and their modifications is evaluated on simulated uncoupled and coupled dynamical systems and for different settings of embedding dimension, time series length and noise level. The corrected measures, and particularly the suggested corrected transfer entropy, turn out to stabilize at the zero level in the absence of causal effect and detect correctly the direction of information flow when it is present. The measures are also evaluated on electroencephalograms (EEG) for the detection of the information flow in the brain of an epileptic patient. The performance of the measures on EEG is interpreted, in view of the results from the simulation study.Comment: 30 pages, 12 figures, accepted to Physical Review

Few-electron quantum dots in III-V ternary alloys: role of fluctuations

We study experimentally the electron transport properties of gated quantum dots formed in InGaAs/InP and InAsP/InP quantum well structures grown by chemical-beam epitaxy. For the case of the InGaAs quantum well, quantum dots form directly underneath narrow gate electrodes due to potential fluctuations. We measure the Coulomb-blockade diamonds in the few-electron regime of a single quantum dot and observe photon-assisted tunneling peaks under microwave irradiation. A singlet-triplet transition at high magnetic field and Coulomb-blockade effects in the quantum Hall regime are also observed. For the InAsP quantum well, an incidental triple quantum dot forms also due to potential fluctuations within a single dot layout. Tunable quadruple points are observed via transport measurements.Comment: 3.3 pages, 3 figures. Added two new subfigures, new references, and improved the tex

A Tuneable Few Electron Triple Quantum Dot

In this paper we report on a tuneable few electron lateral triple quantum dot design. The quantum dot potentials are arranged in series. The device is aimed at studies of triple quantum dot properties where knowing the exact number of electrons is important as well as quantum information applications involving electron spin qubits. We demonstrate tuning strategies for achieving required resonant conditions such as quadruple points where all three quantum dots are on resonance. We find that in such a device resonant conditions at specific configurations are accompanied by novel charge transfer behaviour.Comment: 11 pages, 4 figure

Two-stage Kondo effect in a four-electron artificial atom

An artificial atom with four electrons is driven through a singlet-triplet transition by varying the confining potential. In the triplet, a Kondo peak with a narrow dip at drain-source voltage V_ds=0 is observed. The low energy scale V_ds* characterizing the dip is consistent with predictions for the two-stage Kondo effect. The phenomenon is studied as a function of temperature T and magnetic field B, parallel to the two-dimensional electron gas. The low energy scales T* and B* are extracted from the behavior of the zero-bias conductance and are compared to the low energy scale V_ds* obtained from the differential conductance. Good agreement is found between kT* and |g|muB*, but eV_ds* is larger, perhaps because of nonequilibrium effects.Comment: 7 pages, 7 figures. Added labels on Fig. 3f and one referenc