Influence of sow dietary polyunsaturated fatty acid source on the immunoglobulin profile of piglets

To examine the effect of different n-3 polyunsaturated fatty acid (PUFA) sources in sow diets on piglets’ immunoglobulin (Ig) profile, two groups of twelve sows each were fed different diets from day 45 of pregnancy and during lactation on two commercial farms. On farm I, a palm oil diet (25 g/kg; PALM) and a linseed oil containing diet (20 g/kg; LIN) were fed. On farm II, the same PALM diet and a fish oil containing diet (20 g/kg; FISH) were fed. All diets contained equal amounts of C18:2n-6 (13 g/kg). One day before parturition, blood (for serum) was taken and shortly after parturition, colostrum was taken from the sows (not from sows on farm I) for determination of Ig levels. On day 5 post partum and the day before weaning, blood (for serum) was taken from 4 piglets of six sows per group (24 piglets in total per group; for 5-d old piglets on farm II, only 6 piglets of the FISH group were sampled). In all samples total IgG, IgA, IgM concentration and specific F4-IgG, -IgA and -IgM titer (Log2 titer) against E. coli were determined. On farm I, the sows of the LIN group showed a trend towards lower IgG titers compared to the PALM group around farrowing (P<0.1). On farm II, the sows on the FISH diet showed a significantly (P<0.05) lower F4-IgG titer compared to the sows fed PALM. The colostrum samples on farm II showed no differences between both groups. On farm I, the 5-d old piglets from the LIN group had significantly higher IgA and IgM concentrations and higher F4-IgA and F4-IgM titers (P<0.05). F4-IgA and F4-IgG titers were also significantly higher at weaning in the LIN group compared to the PALM group. On farm II, the piglets of the FISH group had a significantly higher IgG concentration and F4-IgA titer (P<0.05) and a trend towards a higher IgM concentration (P<0.1) around weaning compared to the PALM group. It seems that fish oil in the maternal diet increases total IgG concentration, while linseed oil reduces total IgG and increases total IgA compared to a palm fat containing diet. Both fish and linseed oil seem to have a positive effect on total IgM concentration compared to the palm diet

EnsembleSVM: A Library for Ensemble Learning Using Support Vector Machines

EnsembleSVM is a free software package containing efficient routines to perform ensemble learning with support vector machine (SVM) base models. It currently offers ensemble methods based on binary SVM models. Our implementation avoids duplicate storage and evaluation of support vectors which are shared between constituent models. Experimental results show that using ensemble approaches can drastically reduce training complexity while maintaining high predictive accuracy. The EnsembleSVM software package is freely available online at http://esat.kuleuven.be/stadius/ensemblesvm.Comment: 5 pages, 1 tabl

Even denominator fractional quantum Hall states in higher Landau levels of graphene

An important development in the field of the fractional quantum Hall effect has been the proposal that the 5/2 state observed in the Landau level with orbital index $n = 1$ of two dimensional electrons in a GaAs quantum well originates from a chiral $p$-wave paired state of composite fermions which are topological bound states of electrons and quantized vortices. This state is theoretically described by a "Pfaffian" wave function or its hole partner called the anti-Pfaffian, whose excitations are neither fermions nor bosons but Majorana quasiparticles obeying non-Abelian braid statistics. This has inspired ideas on fault-tolerant topological quantum computation and has also instigated a search for other states with exotic quasiparticles. Here we report experiments on monolayer graphene that show clear evidence for unexpected even-denominator fractional quantum Hall physics in the $n=3$ Landau level. We numerically investigate the known candidate states for the even-denominator fractional quantum Hall effect, including the Pfaffian, the particle-hole symmetric Pfaffian, and the 221-parton states, and conclude that, among these, the 221-parton appears a potentially suitable candidate to describe the experimentally observed state. Like the Pfaffian, this state is believed to harbour quasi-particles with non-Abelian braid statistic

Radiation induced zero-resistance states in GaAs/AlGaAs heterostructures: Voltage-current characteristics and intensity dependence at the resistance minima

High mobility two-dimensional electron systems exhibit vanishing resistance over broad magnetic field intervals upon excitation with microwaves, with a characteristic reduction of the resistance with increasing radiation intensity at the resistance minima. Here, we report experimental results examining the voltage - current characteristics, and the resistance at the minima vs. the microwave power. The findings indicate that a non-linear V-I curve in the absence of microwave excitation becomes linearized under irradiation, unlike expectations, and they suggest a similarity between the roles of the radiation intensity and the inverse temperature.Comment: 3 color figures; publishe

Electrical Transport in High Quality Graphene pnp Junctions

We fabricate and investigate high quality graphene devices with contactless, suspended top gates, and demonstrate formation of graphene pnp junctions with tunable polarity and doping levels. The device resistance displays distinct oscillations in the npn regime, arising from the Fabry-Perot interference of holes between the two pn interfaces. At high magnetic fields, we observe well-defined quantum Hall plateaus, which can be satisfactorily fit to theoretical calculations based on the aspect ratio of the device.Comment: to appear in a special focus issue in New Journal of Physic

Novel metallic and insulating states at a bent quantum Hall junction

A non-planar geometry for the quantum Hall (QH) effect is studied, whereby two quantum Hall (QH) systems are joined at a sharp right angle. When both facets are at equal filling factor nu the junction hosts a channel with non-quantized conductance, dependent on nu. The state is metallic at nu = 1/3, with conductance along the junction increasing as the temperature T drops. At nu = 1, 2 it is strongly insulating, and at nu = 3, 4 shows only weak T dependence. Upon applying a dc voltage bias along the junction, the differential conductance again shows three different behaviors. Hartree calculations of the dispersion at the junction illustrate possible explanations, and differences from planar QH structures are highlighted.Comment: 5 pages, 4 figures, text + figs revised for clarit

Quantum Hall Effect in a Two-Dimensional Electron System Bent by 90 Degrees

Using a new MBE growth technique, we fabricate a two-dimensional electron system which is bent around an atomically sharp 90 degree corner. In the quantum Hall regime under tilted magnetic fields, we can measure equilibration between both co- and counter-propagating edge channels of arbitrary filling factor ratio. We present here 4-point magnetotransport characterization of the corner junction with filling factor combinations which can all be explained using the standard Landauer-Buttiker edge channel picture. The success of this description confirms the realization of a new type of quantum Hall edge geometry.Comment: 4 pages, figures included Typographical errors corrected, reference adde