Shot Noise with Interaction Effects in Single Walled Carbon Nanotubes

We have measured shot noise in single walled carbon nanotubes (SWNT) with good contacts at 4.2 K at low frequencies ($f=600 - 850$ MHz). We find a strong modulation of shot noise over the Fabry-Perot pattern; in terms of differential Fano factor the variation ranges over 0.4 - 1.2. The shot noise variation, in combination with differential conductance, is analyzed using two (spin-degenerate) modes with different, energy-dependent transmission coefficients. No power law dependence of shot noise, as expected for Luttinger liquids, was found in our measurements.Comment: 5 pages, 4 figure

Optimization of Tc-99m-sestamibi/I-123 subtraction SPECT/CT protocol for parathyroid scintigraphy

The purpose of this study was to optimize effective, but technically challenging Tc-99m-sestamibi/I-123 subtraction SPECT/CT protocol for parathyroid scintigraphy. An anthropomorphic parathyroid phantom was set up using a small sphere, a thyroid phantom and a thorax phantom with clinical range of activities of 1231 and Tc-99m. SPECT/CT acquisitions were performed using three collimators (Low Energy High Resolution (LEHR), Low Energy Ultra High Resolution (LEUHR) and Medium Energy Low Penetration (MELP)) and two energy window settings. Images were reconstructed with a combination of four different numbers of iterations and with or without scatter correction. Images were subjected to visual and quantitative evaluation. The effect of collimator, energy window selection and reconstruction parameters had a significant effect on visual appearance and adenoma contrast in parathyroid Tc-99m-sestamibi/I-123 subtraction SPECT/CT. Symmetrical energy windows and ultra-high resolution collimator yielded best results with some improvement with scatter correction.Peer reviewe

Farmer's attitudes affect piglet production parameters

Our results show that farmers' attitudes count: treating the animals humanely, investing in a favourable environment, and having a positive attitude towards new information and scientific research is associated with an above-average productivity on piglet farms. These attitudes, when implemented and concretized in practice, also benefit the animals through a higher standard of welfare

Rationality as the Rule of Reason

The demands of rationality are linked both to our subjective normative perspective (given that rationality is a person-level concept) and to objective reasons or favoring relations (given that rationality is non-contingently authoritative for us). In this paper, I propose a new way of reconciling the tension between these two aspects: roughly, what rationality requires of us is having the attitudes that correspond to our take on reasons in the light of our evidence, but only if it is competent. I show how this view can account for structural rationality on the assumption that intentions and beliefs as such involve competent perceptions of downstream reasons, and explore various implications of the account

Catalyst-free growth of In(As)P nanowires on silicon

The catalyst-free metal organic vapor phase epitaxialgrowth of In(As)P nanowires on silicon substrates is investigated using in situ deposited In droplets as seeds for nanowiregrowth. The thin substrate native oxide is found to play a crucial role in the nanowire formation. The structure of the nanowires is characterized by photoluminescence and electron microscopy measurements. The crystal structure of the InPnanowires is wurtzite with its c axis perpendicular to the nanowire axis. Adding arsenic precursor to the gas phase during growth results in a bimodal photoluminescence spectrum exhibiting peak at the InAsP and InP band gap energies.Peer reviewe

Enhanced luminescence from catalyst-free grown InP nanowires

The surface effects in the optical properties of catalyst-free grownInPnanowires are investigated. Both as-grown nanowires and nanowires treated with hydrofluoric acid are studied using low- and room-temperature continuous-wave and time-resolved photoluminescence measurements and transmission electron microscopy. It is shown that the room-temperature photoluminescence intensity is increased by two orders of magnitude after the surface treatment, and that there is also a significant increase in the double-exponential photoluminescence decay time.Peer reviewe

Measurements of shot noise in single walled carbon nanotubes

We have measured shot noise in single walled carbon nanotubes (SWNT) at 4.2K over frequencies f = 600 – 850 MHz. Here we report results obtained on shot noise without DC bias by applying an AC modulation at ω0 and recording the noise variation at 2ω0: the Fano factor is obtained by extrapolating down to zero excitation amplitude. We also discuss the applicability of this method in samples which have strongly non‐linear IV characteristics like carbon nanotubes. The obtained results are compared with regular differential noise measurements where both DC and AC bias are employed.Peer reviewe