182 research outputs found
High-fidelity state detection and tomography of a single ion Zeeman qubit
We demonstrate high-fidelity Zeeman qubit state detection in a single trapped
88 Sr+ ion. Qubit readout is performed by shelving one of the qubit states to a
metastable level using a narrow linewidth diode laser at 674 nm followed by
state-selective fluorescence detection. The average fidelity reached for the
readout of the qubit state is 0.9989(1). We then measure the fidelity of state
tomography, averaged over all possible single-qubit states, which is 0.9979(2).
We also fully characterize the detection process using quantum process
tomography. This readout fidelity is compatible with recent estimates of the
detection error-threshold required for fault-tolerant computation, whereas
high-fidelity state tomography opens the way for high-precision quantum process
tomography
Quantum gates using electronic and nuclear spins of Yb in a magnetic field gradient
An efficient scheme is proposed to carry out gate operations on an array of
trapped Yb ions, based on a previous proposal using both electronic and
nuclear degrees of freedom in a magnetic field gradient. For this purpose we
consider the Paschen-Back regime (strong magnetic field) and employ a
high-field approximation in this treatment. We show the possibility to suppress
the unwanted coupling between the electron spins by appropriately swapping
states between electronic and nuclear spins. The feasibility of generating the
required high magnetic field is discussed
Spatial variation in the fine-structure constant -- new results from VLT/UVES
(abridged) We present a new analysis of a large sample of quasar
absorption-line spectra obtained using UVES (the Ultraviolet and Visual Echelle
Spectrograph) on the VLT (Very Large Telescope) in Chile. In the VLT sample
(154 absorbers), we find evidence that alpha increases with increasing
cosmological distance from Earth. However, as previously shown, the Keck sample
(141 absorbers) provided evidence for a smaller alpha in the distant absorption
clouds. Upon combining the samples an apparent variation of alpha across the
sky emerges which is well represented by an angular dipole model pointing in
the direction RA=(17.3 +/- 1.0) hr, dec. = (-61 +/- 10) deg, with amplitude
(0.97 +0.22/-0.20) x 10^(-5). The dipole model is required at the 4.1 sigma
statistical significance level over a simple monopole model where alpha is the
same across the sky (but possibly different to the current laboratory value).
The data sets reveal a number of remarkable consistencies: various data cuts
are consistent and there is consistency in the overlap region of the Keck and
VLT samples. Assuming a dipole-only (i.e. no-monopole) model whose amplitude
grows proportionally with `lookback-time distance' (r=ct, where t is the
lookback time), the amplitude is (1.1 +/- 0.2) x 10^(-6) GLyr^(-1) and the
model is significant at the 4.2 sigma confidence level over the null model
[Delta alpha]/alpha = 0). We apply robustness checks and demonstrate that the
dipole effect does not originate from a small subset of the absorbers or
spectra. We present an analysis of systematic effects, and are unable to
identify any single systematic effect which can emulate the observed variation
in alpha.Comment: 47 pages, 35 figures. Accepted for publication by Monthly Notices of
the Royal Astronomical Society. Please see
http://astronomy.swin.edu.au/~mmurphy/pub.html for an ASCII version of table
A1 and the full set of Voigt profile fits for appendix
Social policies, separation, and second birth spacing in Western Europe
OBJECTIVEThis paper studies postseparation fertility behavior. The aim is to investigate whether, and if so how, separation affects second birth spacing in Western European countries.METHODSThis analysis makes use of rich survey data from Belgium, France, Germany, Italy, Spain, and the United Kingdom, as well as from Finnish register data. We thus cover the behavior of a large proportion of the population of Western Europe. We also use descriptive measures, such as Kaplan. Meier survival functions and cumulative incidence curves. In the multivariate analysis, we employ event history modeling to show how education relates to postseparation fertility behavior.RESULTSThere are large differences in postseparation fertility behavior across European countries. For Spain and Italy, we find that only a negligibly small proportion of the population have a second child after separating from the other parent of the firstborn child. The countries with the highest proportion of second children with a new partner are the United Kingdom, Germany, and Finland. In all countries, separation after first birth leads to a sharp increase in the birth interval between first and second births.CONTRIBUTIONOur study is a contribution to the demographic literature that aims at understanding birth spacing patterns in Western Europe. Furthermore, we draw attention to the role of postseparation policies in explaining country differences in fertility behavior in contemporary societies
Feasibility of FDG PET/CT to monitor the response of axillary lymph node metastases to neoadjuvant chemotherapy in breast cancer patients
Novel Cytochrome P450, cyp6a17, Is Required for Temperature Preference Behavior in Drosophila
Perception of temperature is an important brain function for organisms to survive. Evidence suggests that temperature preference behavior (TPB) in Drosophila melanogaster, one of poikilothermal animals, is regulated by cAMP-dependent protein kinase (PKA) signaling in mushroom bodies of the brain. However, downstream targets for the PKA signaling in this behavior have not been identified. From a genome-wide search for the genes regulated by PKA activity in the mushroom bodies, we identified the cyp6a17 Cytochrome P450 gene as a new target for PKA. Our detailed analysis of mutants by genetic, molecular and behavioral assays shows that cyp6a17 is essential for temperature preference behavior. cyp6a17 expression is enriched in the mushroom bodies of the adult brain. Tissue-specific knockdown and rescue experiments demonstrate that cyp6a17 is required in the mushroom bodies for normal temperature preference behavior. This is the first study, to our knowledge, to show PKA-dependent expression of a cytochrome P450 gene in the mushroom bodies and its role as a key factor for temperature preference behavior. Taken together, this study reveals a new PKA-Cytochrome P450 pathway that regulates the temperature preference behavior
A phase II study of sequential neoadjuvant gemcitabine plus doxorubicin followed by gemcitabine plus cisplatin in patients with operable breast cancer: prediction of response using molecular profiling
This study examined the pathological complete response (pCR) rate and safety of sequential gemcitabine-based combinations in breast cancer. We also examined gene expression profiles from tumour biopsies to identify biomarkers predictive of response. Indian women with large or locally advanced breast cancer received 4 cycles of gemcitabine 1200 mg m−2 plus doxorubicin 60 mg m−2 (Gem+Dox), then 4 cycles of gemcitabine 1000 mg m−2 plus cisplatin 70 mg m−2 (Gem+Cis), and surgery. Three alternate dosing sequences were used during cycle 1 to examine dynamic changes in molecular profiles. Of 65 women treated, 13 (24.5% of 53 patients with surgery) had a pCR and 22 (33.8%) had a complete clinical response. Patients administered Gem d1, 8 and Dox d2 in cycle 1 (20 of 65) reported more toxicities, with G3/4 neutropenic infection/febrile neutropenia (7 of 20) as the most common cycle-1 event. Four drug-related deaths occurred. In 46 of 65 patients, 10-fold cross validated supervised analyses identified gene expression patterns that predicted with ⩾73% accuracy (1) clinical complete response after eight cycles, (2) overall clinical complete response, and (3) pCR. This regimen shows strong activity. Patients receiving Gem d1, 8 and Dox d2 experienced unacceptable toxicity, whereas patients on other sequences had manageable safety profiles. Gene expression patterns may predict benefit from gemcitabine-containing neoadjuvant therapy
Resonance enhanced isotope-selective photoionization of YbI for ion trap loading
Neutral Ytterbium (YbI) and singly ionized Ytterbium (YbII) is widely used in
experiments in quantum optics, metrology and quantum information science. We
report on the investigation of isotope selective two-photoionisation of YbI
that allows for efficient loading of ion traps with YbII. Results are presented
on two-colour (399 nm and 369 nm) and single-colour (399 nm) photoionisation
and their efficiency is compared to electron impact ionisation. Nearly
deterministic loading of a desired number of YbII ions into a linear Paul trap
is demonstrated.Comment: 9 pages. Considerably extended and revised version including new dat
Gene expression profiling of tumour epithelial and stromal compartments during breast cancer progression
The progression of ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) marks a critical step in the evolution of breast cancer. There is some evidence to suggest that dynamic interactions between the neoplastic cells and the tumour microenvironment play an important role. Using the whole-genome cDNA-mediated annealing, selection, extension and ligation assay (WG-DASL, Illumina), we performed gene expression profiling on 87 formalin-fixed paraffin-embedded (FFPE) samples from 17 patients consisting of matched IDC, DCIS and three types of stroma: IDC-S ( 10 mm from IDC or DCIS). Differential gene expression analysis was validated by quantitative real time-PCR, immunohistochemistry and immunofluorescence. The expression of several genes was down-regulated in stroma from cancer patients relative to normal stroma from reduction mammoplasties. In contrast, neoplastic epithelium underwent more gene expression changes during progression, including down regulation of SFRP1. In particular, we observed that molecules related to extracellular matrix (ECM) remodelling (e.g. COL11A1, COL5A2 and MMP13) were differentially expressed between DCIS and IDC. COL11A1 was overexpressed in IDC relative to DCIS and was expressed by both the epithelial and stromal compartments but was enriched in invading neoplastic epithelial cells. The contributions of both the epithelial and stromal compartments to the clinically important scenario of progression from DCIS to IDC. Gene expression profiles, we identified differential expression of genes related to ECM remodelling, and specifically the elevated expression of genes such as COL11A1, COL5A2 and MMP13 in epithelial cells of IDC. We propose that these expression changes could be involved in facilitating the transition from in situ disease to invasive cancer and may thus mark a critical point in disease development
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