Coherent Control of a Superconducting Qubit with Dynamically Tunable Qubit-cavity Coupling

We demonstrate coherent control and measurement of a superconducting qubit coupled to a superconducting coplanar waveguide resonator with a dynamically tunable qubit-cavity coupling strength. Rabi oscillations are measured for several coupling strengths showing that the qubit transition can be turned off by a factor of more than 1500. We show how the qubit can still be accessed in the off state via fast flux pulses. We perform pulse delay measurements with synchronized fast flux pulses on the device and observe $T_1$ and $T_2$ times of 1.6 and 1.9 $\mu$s, respectively. This work demonstrates how this qubit can be incorporated into quantum computing architectures.Comment: 4 pages, 4 figure

Methionine synthase interreplacement in diatom cultures and communities : implications for the persistence of B12 use by eukaryotic phytoplankton

Author Posting. © Association for the Sciences of Limnology and Oceanography, 2013. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 58 (2013): 1431–1450, doi:10.4319/lo.2013.58.4.1431.Three proteins related to vitamin B12 metabolism in diatoms were quantified via selected reaction monitoring mass spectrometry: B12-dependent and B12-independent methionine synthase (MetH, MetE) and a B12 acquisition protein (CBA1). B12-mediated interreplacement of MetE and MetH metalloenzymes was observed in Phaeodactylum tricornutum where MetH abundance was highest (0.06 fmol µg−1 protein) under high B12 and MetE abundance increased to 3.25 fmol µg−1 protein under low B12 availability. Maximal MetE abundance was 60-fold greater than MetH, consistent with the expected ∼ 50–100-fold larger turnover number for MetH. MetE expression resulted in 30-fold increase in nitrogen and 40-fold increase in zinc allocated to methionine synthase activity under low B12. CBA1 abundance was 6-fold higher under low-B12 conditions and increased upon B12 resupply to starved cultures. While biochemical pathways that supplant B12 requirements exist and are utilized by organisms such as land plants, B12 use persists in eukaryotic phytoplankton. This study suggests that retention of B12 utilization by phytoplankton results in resource conservation under conditions of high B12 availability. MetE and MetH abundances were also measured in diatom communities from McMurdo Sound, verifying that both these proteins are expressed in natural communities. These protein measurements are consistent with previous studies suggesting that B12 availability influences Antarctic primary productivity. This study illuminates controls on expression of B12-related proteins, quantitatively assesses the metabolic consequences of B12 deprivation, and demonstrates that mass spectrometry–based protein measurements yield insight into the functioning of marine microbial communities.This work was supported by National Science Foundation (NSF) Antarctic Sciences awards 0732665, 1103503, and 0732822; NSF Division of Ocean Science awards 0752291, 0928414, and 1031271; The Gordon and Betty Moore Foundation; Center for Microbial Oceanography Research and Education; an NSF Graduate Research Fellowship (2007037200); and an Environmental Protection Agency Science To Achieve Results (EPA-STAR) Fellowship to E.M.B. (F6E720324)

The solubility–permeability interplay in using cyclodextrins as pharmaceutical solubilizers: Mechanistic modeling and application to progesterone

A quasi-equilibrium mass transport analysis has been developed to quantitatively explain the solubility–permeability interplay that exists when using cyclodextrins as pharmaceutical solubilizers. The model considers the effects of cyclodextrins on the membrane permeability ( P m ) as well as the unstirred water layer (UWL) permeability ( P aq ), to predict the overall effective permeability ( P eff ) dependence on cyclodextrin concentration ( C CD ). The analysis reveals that: (1) UWL permeability markedly increases with increasing C CD since the effective UWL thickness quickly decreases with increasing C CD ; (2) membrane permeability decreases with increasing C CD , as a result of the decrease in the free fraction of drug; and (3) since P aq increases and P m decreases with increasing C CD , the UWL is effectively eliminated and the overall P eff tends toward membrane control, that is, P eff  ≈  P m above a critical C CD . Application of this transport model enabled excellent quantitative prediction of progesterone P eff as a function of HPΒCD concentrations in PAMPA assay, Caco-2 transepithelial studies, and in situ rat jejunal-perfusion model. This work demonstrates that when using cyclodextrins as pharmaceutical solubilizers, a trade-off exists between solubility increase and permeability decrease that must not be overlooked; the transport model presented here can aid in striking the appropriate solubility–permeability balance in order to achieve optimal overall absorption. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2739–2749, 2010Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71376/1/22033_ftp.pd

West Nile Virus Viremia in Wild Rock Pigeons

Feral rock pigeons were screened for neutralizing antibodies to West Nile virus (WNV) during late winter/spring and summer of 2002 and 2003. Additionally, virus isolation from serum was attempted from 269 birds collected during peak transmission periods. The observed viremia levels and seroprevalence indicate that this species could be involved in amplifying WNV in urban settings

Individual and joint trajectories of change in bone, lean mass and physical performance in older men.

BackgroundDeclines in bone, muscle and physical performance are associated with adverse health outcomes in older adults. However, few studies have described concurrent age-related patterns of change in these factors. The purpose of this study was to characterize change in four properties of muscle, physical performance, and bone in a prospective cohort study of older men.MethodsUsing repeated longitudinal data from up to four visits across 6.9 years from up to 4681 men (mean age at baseline 72.7 yrs. ±5.3) participating in the Osteoporotic Fractures in Men (MrOS) Study, we used group-based trajectory models (PROC TRAJ in SAS) to identify age-related patterns of change in four properties of muscle, physical performance, and bone: total hip bone mineral (BMD) density (g/m2) and appendicular lean mass/ht2 (kg/m2), by DXA; grip strength (kg), by hand dynamometry; and walking speed (m/s), by usual walking pace over 6 m. We also described joint trajectories in all pair-wise combinations of these measures. Mean posterior probabilities of placement in each trajectory (or joint membership in latent groups) were used to assess internal reliability of the model. The number of trajectories for each individual factor was limited to three, to ensure that the pair-wise determination of joint trajectories would yield a tractable number of groups as well as model fit considerations.ResultsThe patterns of change identified were generally similar for all measures, with three district groups declining over time at roughly similar rates; joint trajectories revealed similar patterns with no cross-over or convergence between groups. Mean posterior probabilities for all trajectories were similar and consistently above 0.8 indicating reasonable model fit to the data.ConclusionsOur description of trajectories of change with age in bone mineral density, grip strength, walking speed and appendicular lean mass found that groups identified by these methods appeared to have little crossover or convergence of change with age, even when considering joint trajectories of change in these factors

Effects of Exercise and Sertraline on Measures of Coronary Heart Disease Risk in Patients With Major Depression: Results From the SMILE-II Randomized Clinical Trial

To assess the effects of supervised and home-based aerobic exercise training, and antidepressant pharmacotherapy (sertraline) on coronary heart disease (CHD) risk factors in a sample of participants with major depressive disorder (MDD)

Candidate gene analysis of femoral neck trabecular and cortical volumetric bone mineral density in older men.

In contrast to conventional dual-energy X-ray absorptiometry, quantitative computed tomography separately measures trabecular and cortical volumetric bone mineral density (vBMD). Little is known about the genetic variants associated with trabecular and cortical vBMD in humans, although both may be important for determining bone strength and osteoporotic risk. In the current analysis, we tested the hypothesis that there are genetic variants associated with trabecular and cortical vBMD at the femoral neck by genotyping 4608 tagging and potentially functional single-nucleotide polymorphisms (SNPs) in 383 bone metabolism candidate genes in 822 Caucasian men aged 65 years or older from the Osteoporotic Fractures in Men Study (MrOS). Promising SNP associations then were tested for replication in an additional 1155 men from the same study. We identified SNPs in five genes (IFNAR2, NFATC1, SMAD1, HOXA, and KLF10) that were robustly associated with cortical vBMD and SNPs in nine genes (APC, ATF2, BMP3, BMP7, FGF18, FLT1, TGFB3, THRB, and RUNX1) that were robustly associated with trabecular vBMD. There was no overlap between genes associated with cortical vBMD and trabecular vBMD. These findings identify novel genetic variants for cortical and trabecular vBMD and raise the possibility that some genetic loci may be unique for each bone compartment