133 research outputs found
Testing the stability of fundamental constants with the 199Hg+ single-ion optical clock
Over a two-year duration, we have compared the frequency of the 199Hg+ 5d106s
2S 1/2 (F=0) 5d9 6s2 2D 5/2 (F=2) electric-quadrupole transition at 282 nm
with the frequency of the ground-state hyperfine splitting in neutral 133Cs.
These measurements show that any fractional time variation of the ratio
nu(Cs)/nu(Hg) between the two frequencies is smaller than +/- 7 10^-15 / yr (1
sigma uncertainty). According to recent atomic structure calculations, this
sets an upper limit to a possible fractional time variation of g(Cs) m_e / m_p
alpha^6.0 at the same level.Comment: 4 pages with 3 figures. RevTeX 4, Submitted to Phys. Rev. Let
Low-concentration, continuous brachial plexus block in the management of Purple Glove Syndrome: a case report
<p>Abstract</p> <p>Introduction</p> <p>Purple Glove Syndrome is a devastating complication of intravenous phenytoin administration. Adequate analgesia and preservation of limb movement for physiotherapy are the two essential components of management.</p> <p>Case presentation</p> <p>A 26-year-old Tamil woman from India developed Purple Glove Syndrome after intravenous administration of phenytoin. She was managed conservatively by limb elevation, physiotherapy and oral antibiotics. A 20G intravenous cannula was inserted into the sheath of her brachial plexus and a continuous infusion of bupivacaine at a low concentration (0.1%) with fentanyl (2 μg/ml) at a rate of 1 to 2 ml/hr was given. She had adequate analgesia with preserved motor function which helped in physiotherapy and functional recovery of the hand in a month.</p> <p>Conclusion</p> <p>A continuous blockade of the brachial plexus with a low concentration of bupivacaine and fentanyl helps to alleviate the vasospasm and the pain while preserving the motor function for the patient to perform active movements of the finger and hand.</p
Evaluating and Minimizing Distributed Cavity Phase Errors in Atomic Clocks
We perform 3D finite element calculations of the fields in microwave cavities
and analyze the distributed cavity phase errors of atomic clocks that they
produce. The fields of cylindrical cavities are treated as an azimuthal Fourier
series. Each of the lowest components produces clock errors with unique
characteristics that must be assessed to establish a clock's accuracy. We
describe the errors and how to evaluate them. We prove that sharp structures in
the cavity do not produce large frequency errors, even at moderately high
powers, provided the atomic density varies slowly. We model the amplitude and
phase imbalances of the feeds. For larger couplings, these can lead to
increased phase errors. We show that phase imbalances produce a novel
distributed cavity phase error that depends on the cavity detuning. We also
design improved cavities by optimizing the geometry and tuning the mode
spectrum so that there are negligible phase variations, allowing this source of
systematic error to be dramatically reduced.Comment: To appear in Metrologi
Looking to the future of zebrafish as a model to understand the genetic basis of eye disease
In this brief commentary, we provide some of our thoughts and opinions on the current and future use of zebrafish to model human eye disease, dissect pathological progression and advance in our understanding of the genetic bases of microphthalmia, andophthalmia and coloboma (MAC) in humans. We provide some background on eye formation in fish and conservation and divergence across vertebrates in this process, discuss different approaches for manipulating gene function and speculate on future research areas where we think research using fish may prove to be particularly effective
Genetic determinants of telomere length from 109,122 ancestrally diverse whole-genome sequences in TOPMed
Genetic studies on telomere length are important for understanding age-related diseases. Prior GWAS for leukocyte TL have been limited to European and Asian populations. Here, we report the first sequencing-based association study for TL across ancestrally-diverse individuals (European, African, Asian and Hispanic/Latino) from the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. We used whole genome sequencing (WGS) of whole blood for variant genotype calling and the bioinformatic estimation of telomere length in n=109,122 individuals. We identified 59 sentinel variants (p-value OBFC1indicated the independent signals colocalized with cell-type specific eQTLs for OBFC1 (STN1). Using a multi-variant gene-based approach, we identified two genes newly implicated in telomere length, DCLRE1B (SNM1B) and PARN. In PheWAS, we demonstrated our TL polygenic trait scores (PTS) were associated with increased risk of cancer-related phenotypes
Whole-exome sequence analysis of anthropometric traits illustrates challenges in identifying effects of rare genetic variants
Anthropometric traits, measuring body size and shape, are highly heritable and significant clinical risk factors for cardiometabolic disorders. These traits have been extensively studied in genome-wide association studies (GWASs), with hundreds of genome-wide significant loci identified. We performed a whole-exome sequence analysis of the genetics of height, body mass index (BMI) and waist/hip ratio (WHR). We meta-analyzed single-variant and gene-based associations of whole-exome sequence variation with height, BMI, and WHR in up to 22,004 individuals, and we assessed replication of our findings in up to 16,418 individuals from 10 independent cohorts from Trans-Omics for Precision Medicine (TOPMed). We identified four trait associations with single-nucleotide variants (SNVs; two for height and two for BMI) and replicated the LECT2 gene association with height. Our expression quantitative trait locus (eQTL) analysis within previously reported GWAS loci implicated CEP63 and RFT1 as potential functional genes for known height loci. We further assessed enrichment of SNVs, which were monogenic or syndromic variants within loci associated with our three traits. This led to the significant enrichment results for height, whereas we observed no Bonferroni-corrected significance for all SNVs. With a sample size of ∼20,000 whole-exome sequences in our discovery dataset, our findings demonstrate the importance of genomic sequencing in genetic association studies, yet they also illustrate the challenges in identifying effects of rare genetic variants
Evaluation of the anesthetic effect of epinephrine-free articaine and mepivacaine through quantitative sensory testing
Anaerobiosis revisited: growth of Saccharomyces cerevisiae under extremely low oxygen availability
The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein production. It is also a model organism for studies on cell physiology and genetic regulation. Its ability to grow under anaerobic conditions is of interest in many industrial applications. Unlike industrial bioreactors with their low surface area relative to volume, ensuring a complete anaerobic atmosphere during microbial cultivations in the laboratory is rather difficult. Tiny amounts of O2 that enter the system can vastly influence product yields and microbial physiology. A common procedure in the laboratory is to sparge the culture vessel with ultrapure N2 gas; together with the use of butyl rubber stoppers and norprene tubing, O2 diffusion into the system can be strongly minimized. With insights from some studies conducted in our laboratory, we explore the question ‘how anaerobic is anaerobiosis?’. We briefly discuss the role of O2 in non-respiratory pathways in S. cerevisiae and provide a systematic survey of the attempts made thus far to cultivate yeast under anaerobic conditions. We conclude that very few data exist on the physiology of S. cerevisiae under anaerobiosis in the absence of the anaerobic growth factors ergosterol and unsaturated fatty acids. Anaerobicity should be treated as a relative condition since complete anaerobiosis is hardly achievable in the laboratory. Ideally, researchers should provide all the details of their anaerobic set-up, to ensure reproducibility of results among different laboratories.
A correction to this article is available online at http://eprints.whiterose.ac.uk/131930/
https://doi.org/10.1007/s00253-018-9036-
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