Randomized benchmarking of multiqubit gates.

We describe an extension of single-qubit gate randomized benchmarking that measures the error of multiqubit gates in a quantum information processor. This platform-independent protocol evaluates the performance of Clifford unitaries, which form a basis of fault-tolerant quantum computing. We implemented the benchmarking protocol with trapped ions and found an error per random two-qubit Clifford unitary of 0.162±0.008, thus setting the first benchmark for such unitaries. By implementing a second set of sequences with an extra two-qubit phase gate inserted after each step, we extracted an error per phase gate of 0.069±0.017. We conducted these experiments with transported, sympathetically cooled ions in a multizone Paul trap-a system that can in principle be scaled to larger numbers of ions.

Preclinical comparison in AR4-2J tumor-bearing mice of four radiolabeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-somatostatin analogs for tumor diagnosis and internal radiotherapy.

Somatostatin analogs labeled with radionuclides are of considerable interest in nuclear oncology as diagnostic or therapeutic tools for somatostatin receptor (SSTR)-expressing tumors. We investigated the suitability of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) as a replacement for the widely used diethylenetriaminepentaacetic acid, to enable stable labeling of somatostatin analogs with both therapeutic (90Y) and diagnostic (111In) radionuclides. The three clinically relevant somatostatin agonists, octreotide, vapreotide, and lanreotide, together with the newly designed Tyr3-octreotide (TyrOc), were conjugated to DOTA and labeled with 90Y or 111In. For all DOTA-somatostatin analogs tested, irrespective of the incorporated radionuclide, we observed favorable biodistribution profiles in AR4-2J tumor-bearing mice: 1) a rapid clearance from all SSTR-negative tissues except kidney; 2) a specific uptake in SSTR-positive tissues, including tumor; and 3) an excellent tumor penetration. The main route of excretion was via the kidneys. Nevertheless, DOTATOC was clearly superior to the other DOTA-somatostatin analogs tested, as well as OctreoScan, as indicated by the highest tumor-to-nontarget-tissue ratio, including the tumor-to-SSTR-positive-tissue ratios. The presence of different SSTR subtypes in the SSTR-positive tissues possibly contributes to these differential uptakes. We assume that the very favorable behavior of DOTATOC in our mouse model makes this radioligand very promising for future applications in nuclear oncology.

The preterm prediction study: maternal stress is associated with spontaneous preterm birth at less than thirty-five weeks' gestation. National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network.

OBJECTIVE: Our purpose was to determine whether various measures of poor psychosocial status in pregnancy are associated with spontaneous preterm birth, fetal growth restriction, or low birth weight. STUDY DESIGN: Anxiety, stress, self-esteem, mastery, and depression were assessed at 25 to 29 weeks in 2593 gravid women by use of a 28-item Likert scale. Scores for each psychosocial subscale were determined, and an overall psychosocial score was calculated. Scores were divided into quartiles, and the lowest quartile scores were used to define poor psychosocial status. The percent spontaneous preterm birth, low birth weight, and fetal growth restriction in women with low and high psychosocial scores were compared. Logistic regression analyses provided the odds ratios and 95% confidence intervals. RESULTS: Analyses revealed that stress was significantly associated with spontaneous preterm birth and with low birth weight with odds ratios of 1.16, p = 0.003, and 1.08, p = 0.02, respectively, for each point on the scale. A low score on the combined scale or on any subscale other than stress did not predict spontaneous preterm birth, fetal growth restriction, or low birth weight. After multivariate adjustment was performed for psychosocial status, substance use, and demographic traits, black race was the only variable significantly associated with spontaneous preterm birth, fetal growth restriction, and low birth weight; stress and low education were associated with spontaneous preterm birth and low birth weight. CONCLUSION: Stress was associated with spontaneous preterm birth and low birth weight even after adjustment for maternal demographic and behavioral characteristics. Black race continues to be a significant predictor of spontaneous preterm birth, fetal growth restriction, and low birth weight even after adjustment for stress, substance use, and other demographic factors.

Measured power distribution across the Bausch and Lomb Soflens (PAI) Bifocal.

The power distribution across Bausch and Lomb Soflens PAI Bifocal lenses was measured using a series of double aperture stops on a lensometer. The add power at different distances from the lens center is presented. A gradual increase in plus power approximately equivalent to an aspheric back surface of an eccentricity of 0.75 was found. The change in add with change in apical radius (lens distance power) is also reported. The measured change is compared to the calculated power change over the same radius range.

Influence of suspending media upon the susceptibility of Pseudomonas aeruginosa NCTC 6750 and its spheroplasts to polymyxin B.

The lytic and bactericidal actions of polymyxin B on whole cells and spheroplasts of Pseudomonas aeruginosa varied markedly with the suspending media, and there was little correlation between them. Relative rates of lysis of these preparations and also of Bacillus megaterium protoplasts suggested that polymyxin causes progressive damage to the cytoplasmic membrane, such that membrane permeability towards various ions increased as follows: K(+) > Na(+) > NO(3) (-) > Cl(-), Ca(2+), H(2)PO(4) (-)/HPO(4) (2-). Impermeant compounds, such as NaCl and sucrose, protected whole cells against lysis but not against death. It is suggested that lysis of whole cells by polymyxin is a secondary effect, resulting from entry of solutes normally excluded by the cytoplasmic membrane and the fragility of the damaged outer membrane. Because the degree of lysis varies with the external solutes, it should be treated with caution as a descriptor of polymyxin activity.

Excretion and distribution studies in rats with two forms of 14carbon-labelled polyvinylpyrrolidone with a relatively low mean molecular weight after intravenous administration.

Excretion and autoradiographic distribution studies were performed in rats with two 14C-labelled polyvinylpyrrolidone preparations, both of relatively low mean molecular weight but different in molecular weight distribution. At different time intervals after i.v. administration, elimination of radioactivity was found to be more complete for the preparation with the smallest fraction of molecules having a weight of over 25000, which is approximately the weight limit for rapid glomerular filtration in the rat. Our study demonstrates that the retention of PVP in organs, which in the literature are mentioned as target organs for PVP-toxicity, can be largely prevented by decreasing the fraction of molecules with a weight of more than 25000.