Individual addressing and state readout of trapped ions utilizing rf- micromotion

A new scheme for the individual addressing of ions in a trap is described that does not rely on light beams tightly focused onto only one ion. The scheme utilizes ion micromotion that may be induced in a linear trap by dc offset potentials. Thus coupling an individual ion to the globally applied light fields corresponds to a mere switching of voltages on a suitable set of compensation electrodes. The proposed scheme is especially suitable for miniaturized rf (Paul) traps with typical dimensions of about 20-40 microns.Comment: 3 pages, 5 figure

Assessing measurement invariance of a health-related quality-of-life questionnaire in radiotherapy patients

Objective: If the assumption of measurement invariance is not tested, we cannot be sure whether differences observed are due to true differences in health-related quality-of-life (HRQoL), or are measurement artifacts. We aim to investigate this assumption in a sample of heterogeneous cancer patients, focusing on whether age, sex, previous treatment for cancer, and information regarding treatment preferences result in biased HRQoL scores. Methods: 155 cancer patients who were about to begin their first session of radiotherapy were included. HRQoL was measured using the EORTC QLQ-C30. Structural equation modeling was applied to assess whether there was a violation of the assumption of invariance. Results: A satisfactory single construct (Functioning HRQoL) measurement model was found and two violations of invariance were identified. Irrespective of patients’ Functioning HRQoL, older patients reported worse physical functioning and patients who had received treatment prior to radiotherapy reported worse emotional functioning than we would otherwise expect. Conclusions: In the present study, accounting for measurement bias lead to a substantial improvement in the overall fit of the model. By ignoring the bias, we would have concluded that the model fit was unsatisfactory. The findings underline the importance of investigating measurement invariance in scales designed for heterogeneous samples

Search for Small Trans-Neptunian Objects by the TAOS Project

The Taiwan-America Occultation Survey (TAOS) aims to determine the number of small icy bodies in the outer reach of the Solar System by means of stellar occultation. An array of 4 robotic small (D=0.5 m), wide-field (f/1.9) telescopes have been installed at Lulin Observatory in Taiwan to simultaneously monitor some thousand of stars for such rare occultation events. Because a typical occultation event by a TNO a few km across will last for only a fraction of a second, fast photometry is necessary. A special CCD readout scheme has been devised to allow for stellar photometry taken a few times per second. Effective analysis pipelines have been developed to process stellar light curves and to correlate any possible flux changes among all telescopes. A few billion photometric measurements have been collected since the routine survey began in early 2005. Our preliminary result of a very low detection rate suggests a deficit of small TNOs down to a few km size, consistent with the extrapolation of some recent studies of larger (30--100 km) TNOs.Comment: 4 pages, 3 figures, IAU Symposium 23

An assessment of the strength of knots and splices used as eye terminations in a sailing environment

Research into knots, splices and other methods of forming an eye termination has been limited, despite the fact that they are essential and strongly affect the performance of a rope. The aim of this study was to carry out a comprehensive initial assessment of the breaking strength of eye terminations commonly used in a sailing environment, thereby providing direction for further work in the field. Supports for use in a regular tensile testing machine were specially developed to allow individual testing of each sample and a realistic spread of statistical data to be obtained. Over 180 break tests were carried out on four knots (the bowline, double bowline, figure-of-eight loop and perfection loop) and two splices (three-strand eye splice and braid-on-braid splice). The factors affecting their strength were investigated. A statistical approach to the analysis of the results was adopted. The type of knot was found to have a significant effect on the strength. This same effect was seen in both types of rope construction (three-strand and braid-on-braid). Conclusions were also drawn as to the effect of splice length, eye size, manufacturer and rope diameter on the breaking strength of splices. Areas of development and further investigation were identified

First-principles study of the structural energetics of PdTi and PtTi

The structural energetics of PdTi and PtTi have been studied using first-principles density-functional theory with pseudopotentials and a plane-wave basis. We predict that in both materials, the experimentally reported orthorhombic $B19$ phase will undergo a low-temperature phase transition to a monoclinic $B19'$ ground state. Within a soft-mode framework, we relate the $B19$ structure to the cubic $B2$ structure, observed at high temperature, and the $B19'$ structure to $B19$ via phonon modes strongly coupled to strain. In contrast to NiTi, the $B19$ structure is extremely close to hcp. We draw on the analogy to the bcc-hcp transition to suggest likely transition mechanisms in the present case.Comment: 8 pages 5 figure

Baryon Tri-local Interpolating Fields

We systematically investigate tri-local (non-local) three-quark baryon fields with U_L(2)*U_R(2) chiral symmetry, according to their Lorentz and isospin (flavor) group representations. We note that they can also be called as "nucleon wave functions" due to this full non-locality. We study their chiral transformation properties and find all the possible chiral multiplets consisting J=1/2 and J=3/2 baryon fields. We find that the axial coupling constant |g_A| = 5/3 is only for nucleon fields belonging to the chiral representation (1/2,1)+(1,1/2) which contains both nucleon fields and Delta fields. Moreover, all the nucleon fields belonging to this representation have |g_A| = 5/3.Comment: 8 pages, 3 tables, accepted by EPJ

The Yamato-type (CY) carbonaceous chondrite group: Analogues for the surface of asteroid Ryugu?

We report new mineralogical, petrographic and noble gas analyses of the carbonaceous chondrite meteorites Y-82162 (C1/2ung), Y-980115 (CI1), Y-86029 (CI1), Y-86720 (C2ung), Y-86789 (C2ung), and B-7904 (C2ung). Combining our results with literature data we show that these meteorites experienced varying degrees of aqueous alteration followed by short-lived thermal metamorphism at temperatures of >500 °C. These meteorites have similar mineralogy, textures and chemical characteristics suggesting that they are genetically related, and we strongly support the conclusion of Ikeda (1992) that they form a distinct group, the CYs (“Yamato-type”). The CY chondrites have the heaviest oxygen isotopic compositions (δ17O ˜12‰, δ18O ˜22‰) of any meteorite group, high abundances of Fe-sulphides (˜10 ‒ 30 vol%) and phosphates, and contain large grains of periclase and unusual objects of secondary minerals not reported in other carbonaceous chondrites. These features cannot be attributed to parent body processes alone, and indicate that the CYs had a different starting mineralogy and/or alteration history to other chondrite groups, perhaps because they formed in a different region of the protoplanetary disk. The short cosmic-ray exposure ages (≤1.3 Ma) of the CY chondrites suggest that they are derived from a near-Earth source, with recent observations by the Hayabusa2 spacecraft highlighting a possible link to the rubble-pile asteroid Ryugu

Pion production in the 40Ar+40Ca reaction at 1.05 GeV/nucleon

Pion-production cross sections have been measured for the reaction 40Ar+40Ca--> pi ++X at a laboratory energy of 1.05 GeV/nucleon. A maximum in the pi + cross section occurs at mid-rapidity, which is anomalous relative to p+p and p+nucleus reactions and compared to many other heavy-ion reactions. Calculations based on cascade and thermal models fail to fit the data