Analysis of shot noise suppression in mesoscopic cavities in a magnetic field

We present a numerical investigation of shot noise suppression in mesoscopic cavities and an intuitive semiclassical explanation of the behavior observed in the presence of an orthogonal magnetic field. In particular, we conclude that the decrease of shot noise for increasing magnetic field is the result of the interplay between the diameter of classical cyclotron orbits and the width of the apertures defining the cavity. Good agreement with published experimental results is obtained, without the need of introducing fitting parameters.Comment: 5 pages, 3 figures, contents changed (final version

Positive Cross Correlations in a Normal-Conducting Fermionic Beam Splitter

We investigate a beam splitter experiment implemented in a normal conducting fermionic electron gas in the quantum Hall regime. The cross-correlations between the current fluctuations in the two exit leads of the three terminal device are found to be negative, zero or even positive depending on the scattering mechanism within the device. Reversal of the cross-correlations sign occurs due to interaction between different edge-states and does not reflect the statistics of the fermionic particles which `antibunch'.Comment: 4 pages, 4 figure

The effect of symmetry class transitions on the shot noise in chaotic quantum dots

Using the random matrix theory (RMT) approach, we calculated the weak localization correction to the shot noise power in a chaotic cavity as a function of magnetic field and spin-orbit coupling. We found a remarkably simple relation between the weak localization correction to the conductance and to the shot noise power, that depends only on the channel number asymmetry of the cavity. In the special case of an orthogonal-unitary crossover, our result coincides with the prediction of Braun et. al [J. Phys. A: Math. Gen. {\bf 39}, L159-L165 (2006)], illustrating the equivalence of the semiclassical method to RMT.Comment: 4 pages, 1 figur

False memory for analogical inferences: An indicator of text representational change but not of conceptual change

Se puso a prueba si la falsa memoria de inferencias analógicas implica un cambio conceptual acerca del análogo meta (AM), tal como sugieren, por ejemplo, Blanchette y Dunbar (2002), o sólo un cambio en la representación del texto meta. En el primer experimento un grupo que recibió un análogo base (AB) después de leer un análogo meta cometió falsos reconocimientos de inferencias analógicas en mayor medida que un grupo sin AB. No hubo sin embargo diferencias entre aquellos participantes que cometieron falsos reconocimientos y los que no en cuanto al grado de acuerdo con las inferencias. En el segundo experimento se obtuvieron los mismos resultados en un grupo en el que se controló que los participantes hubieran generado las inferencias esperadas. Se concluye que la falsa memoria de inferencias analógicas es un indicador de cambio en la representación del texto meta pero no de cambio conceptual con respecto al tema tratado por el texto meta.Two experiments investigated whether the false memory for analogical inferences implies a conceptual change of the target analog (TA), as suggested, for example, by Blanchette and Dunbar (2002), or only a representational change of the target text. In the first experiment a group of participants that received a source analog (SA) after having read a TA, produced more false recognitions of analogical inferences than a group without a SA. However, there was no difference between the participants who misrecognized analogical inferences and the ones who did not on the level of agreement with those inferences. In the second experiment the same results were obtained in a group where the generation of the expected inferences was controlled. These experiments show that the false memory for analogical inferences is an indicator of representational change of the target text but it is not an indicator of conceptual change of the target issue described by the target text

’n Sosiologiese perspektief op die literêre komposisie van die Sinaikompleks (Eksodus 19-34)

A sociological perspective on the literary composition of the Sinai complex (Exodus 19-34)The elaborate account of Exodus 19-34 is rooted in a pre-exilic Mountain of God tradition which arose primarily from the imagery of divine presence that is assumed in the description of theophany. Deuteronomistic and priestly redactors both significantly expanded this pre-exilic tradition by anchoring their legislation in this event. The underlying motif of the final redaction of the entire Sinai complex reflects rivalry between priestly houses during the Persian period, one tracing its lineage to Moses (Levites) and the other its lineage to Aaron (Zadokites)

Metabolism of Glycollate by Lemna minor L. Grown on Nitrate or Ammonium as Nitrogen Source

Marques, I. A., Oberholzer, M. J. and Erismann, K. H. 1985. Metabolism of glycollate by Lemna minor L. grown on nitrate or ammonium as nitrogen source.—J. exp. Bot. 36: 1685-1697. Duckweed, Lemna minor L., grown on inorganic nutrient solutions containing either NH4+ or NO3− as nitrogen source was allowed to assimilate [1-14C]- or [2-14C]glycollate during a 20 min period in darkness or in light. The incorporation of radioactivity into water-soluble metabolites, the insoluble fraction, and into the CO2 released was measured. In addition the extractable activity of phosphoenolpyruvate carboxylase was determined. During the metabolism of [2-14C]glycollate in darkness, as well as in the light, NH4+ grown plants evolved more 14CO2 than NO3− grown plants. Formate was labelled only from [2-14C]glycollate and in NH4+ grown plants it was significantly less labelled in light than in darkness. In NO3− grown plants formate showed similar radioactivity after dark and light labelling. The radioactivity in glycine was little influenced by the nitrogen source. Amounts of radioactivity in serine implied that the further metabolism of serine was reduced in darkness compared with its metabolism in the light under both nitrogen regimes. In illuminated NH4+ plants, serine was labelled through a pathway starting from phosphoglycerate. After [1-14C]glycollate feeding NH4+ grown plants contained markedly more radioactive aspartate and malate than NO3− plants indicating a stimulated phosphoenolpyruvate carboxylation in plants grown on NH4

Shot noise of series quantum point contacts intercalating chaotic cavities

Shot noise of series quantum point contacts forming a sequence of cavities in a two dimensional electron gas are studied theoretically and experimentally. Noise in such a structure originates from local scattering at the point contacts as well as from chaotic motion of the electrons in the cavities. We found that the measured shot noise is in reasonable agreement with our theoretical prediction taking the cavity noise into account.Comment: 4 pages, 5 figure

Precious metals as safe haven assets in the South African market

Abstract: The role of precious metals as hedges and safe havens has been extensively studied across various markets. However, no precious metals other than gold have been considered in a South African setting. This study extends previous literature by making use of the methodology established by Baur and Lucey (2010) to determine which of the four precious metals provides the most viable hedge and safe haven in relation to the domestic stock and bond markets for South African investors? The results suggest that all four precious metals have significant hedging properties in relation to domestic bond market but not the stock market. It was also determined that while all four metals contain safe haven properties, gold is the only precious metal to act as a significant safe haven against both South African stocks and bonds

Quantized Transport in Graphene p-n Junctions in Magnetic Field

Recent experimental work on locally gated graphene layers resulting in p-n junctions have revealed quantum Hall effect in their transport behavior. We explain the observed conductance quantization which is fractional in the bipolar regime and integer in the unipolar regime in terms of quantum Hall edge modes propagating along and across the p-n interface. In the bipolar regime the electron and hole modes can mix at the p-n boundary, leading to current partition and quantized shot noise plateaus similar to those of conductance, while in the unipolar regime transport is noiseless. These quantum Hall phenomena reflect the massless Dirac character of charge carriers in graphene, with particle-hole interplay manifest in mode mixing and noise in the bipolar regime.Comment: 4 pages, 3 figures, available online at: http://www.sciencemag.org/cgi/content/abstract/114467