248 research outputs found
Generalized Hyper-Ramsey Resonance with separated oscillating fields
An exact generalization of the Ramsey transition probability is derived to
improve ultra-high precision measurement and quantum state engineering when a
particle is subjected to independently-tailored separated oscillating fields.
The phase-shift accumulated at the end of the interrogation scheme offering
high-level control of quantum states throughout various laser parameters
conditions. The Generalized Hyper-Ramsey Resonance based on independent
manipulation of interaction time, field amplitude, phase and frequency detuning
is presented to increase the performance of next generation of atomic,
molecular and nuclear clocks, to upgrade high resolution frequency measurement
in Penning trap mass spectrometry and for a better control of light induced
frequency shifts in matter wave interferometers or quantum information
processing.Comment: accepted for publication in Phys. Rev.
Composite pulses in Hyper-Ramsey spectroscopy for the next generation of atomic clocks
The next generation of atomic frequency standards based on an ensemble of
neutral atoms or a single-ion will provide very stringent tests in metrology,
applied and fundamental physics requiring a new step in very precise control of
external systematic corrections. In the proceedings of the 8th Symposium on
Frequency Standards and Metrology, we present a generalization of the recent
Hyper-Ramsey spectroscopy with separated oscillating fields using composites
pulses in order to suppress field frequency shifts induced by the interrogation
laser itself. Sequences of laser pulses including specific selection of phases,
frequency detunings and durations are elaborated to generate spectroscopic
signals with a strong reduction of the light-shift perturbation by off resonant
states. New optical clocks based on weakly allowed or completely forbidden
transitions in atoms, ions, molecules and nuclei will benefit from these
generalized Ramsey schemes to reach relative accuracies well below the
10 level.Comment: accepted as proceedings of the 8th Symposium on Frequency Standards
and Metrology (Potsdam Germany, 12-16 october 2015
Synthetic Frequency Protocol in the Ramsey Spectroscopy of Clock Transitions
We develop an universal method to significantly suppress probe-induced shifts
in any types of atomic clocks using the Ramsey spectroscopy. Our approach is
based on adaptation of the synthetic frequency concept [V. I. Yudin, et al.,
Phys. Rev. Lett. 107, 030801 (2011)] (previously developed for BBR shift
suppression) to the Ramsey spectroscopy with the use of interrogations for
different dark time intervals. Universality of the method consists in
arbitrariness of the possible Ramsey schemes. However, most extremal results
are obtained in combination with so-called hyper-Ramsey spectroscopy [V. I.
Yudin, et al., Phys. Rev. A 82, 011804(R) (2010)]. In the latter case, the
probe-induced frequency shifts can be suppressed considerably below a
fractional level of 10 practically for any optical atomic clocks, where
this shift previously was metrologically significant. The main advantage of our
method in comparison with other radical hyper-Ramsey approaches [R. Hobson, et
al., Phys. Rev. A 93, 010501(R) (2016); T. Zanon-Willette, et al., Phys. Rev. A
93, 042506 (2016)] consist in much greater efficiency and resistibility in the
presence of decoherentization.Comment: 9 pages, 7 figure
Quantum engineering of atomic phase-shifts in optical clocks
Quantum engineering of time-separated Raman laser pulses in three-level
systems is presented to produce an ultra-narrow optical transition in bosonic
alkali-earth clocks free from light shifts and with a significantly reduced
sensitivity to laser parameter fluctuations. Based on a quantum artificial
complex-wave-function analytical model, and supported by a full density matrix
simulation including a possible residual effect of spontaneous emission from
the intermediate state, atomic phase-shifts associated to Ramsey and
Hyper-Ramsey two-photon spectroscopy in optical clocks are derived. Various
common-mode Raman frequency detunings are found where the frequency shifts from
off-resonant states are canceled, while strongly reducing their uncertainties
at the 10 level of accuracy.Comment: accepted for publication in PR
Community recreation’s role in pre-adolescent girls’ participation and retention in youth sports
Community recreation facilities are an important resource in closing programming and participatory gender gaps often seen in youth sports. Therefore, the purpose of this research study is to examine the motivational climate of community recreation centers in the participation of pre-adolescent girls in youth sports. In doing so, six pre-adolescent girls participation rates in youth community recreation sports can be specified. Lastly, this research aims to use principles highlighted in Self Determination Theory (SDT) to demonstrate a link between participation of pre-adolescent girls’ in youth sports and motivational climate. SDT considers the motivational climate of facilities, participants’ sense of freedom of choice in activity preference, and participants’ skill proficiency as factors associated with continued sport/physical activity participation (Deci & Ryan, 2000). A multiple-case design was implemented to understand this phenomenon. Based on this study’s findings in terms of the six participants, the following conclusions can be made: a) Overall, it was found that the pre-adolescent girls experienced autonomy, relatedness and competence in their sports practice environment at a local community recreation center. b) Coaches had a direct influence on the autonomy within the sports practice environment experienced by the pre-adolescent girl participants. When coaches practice schedule and structure was rigid and uniformed, it lessened the perception of autonomy. When coaches minimized control over the practice schedule, and gave participants choices, participants’ perception of autonomy intensified. c) Participants’ connection within the sports practice environment was linked to receiving praise and positive feedback from teammates and coach. Participants acknowledged that physical displays of praise, high-fives, and handshakes reinforced their sense of belonging to the team. d) Most of the participants felt competent in their skill level in youth basketball. Participants acknowledged feeling challenged by teammates and coach to perform skills. The challenges that participants experienced in their practice environment, aided in their perception of competency. Participants viewed criticism from coaches and teammates as helpful and a way to strengthen the team and increase individual competencies. e) All participants acknowledged they would like to continue playing youth basketball after this current season at their local community recreation center. f) Most of the participants considered their family and local recreation staff as a source of encouragement to continue participating in youth basketball, either at a local community recreation center or at their local school. g) Some of the participants acknowledged having a desire to play other sports besides youth basketball. Participants posed questions about how to sign up for other sports at their community recreation center. Many of the participants felt limited in the sports that are offered at their community recreation center. h) The sports practice environment at each local community recreation center, provided participants with a setting to experience self-determination and nurtured motivation to continue participating in youth sports
Generation and quality control of lipidomics data for the alzheimers disease neuroimaging initiative cohort.
Alzheimers disease (AD) is a major public health priority with a large socioeconomic burden and complex etiology. The Alzheimer Disease Metabolomics Consortium (ADMC) and the Alzheimer Disease Neuroimaging Initiative (ADNI) aim to gain new biological insights in the disease etiology. We report here an untargeted lipidomics of serum specimens of 806 subjects within the ADNI1 cohort (188 AD, 392 mild cognitive impairment and 226 cognitively normal subjects) along with 83 quality control samples. Lipids were detected and measured using an ultra-high-performance liquid chromatography quadruple/time-of-flight mass spectrometry (UHPLC-QTOF MS) instrument operated in both negative and positive electrospray ionization modes. The dataset includes a total 513 unique lipid species out of which 341 are known lipids. For over 95% of the detected lipids, a relative standard deviation of better than 20% was achieved in the quality control samples, indicating high technical reproducibility. Association modeling of this dataset and available clinical, metabolomics and drug-use data will provide novel insights into the AD etiology. These datasets are available at the ADNI repository at http://adni.loni.usc.edu/
Interleukin-6 gene (IL-6): a possible role in brain morphology in the healthy adult brain
Background: Cytokines such as interleukin 6 (IL-6) have been implicated in dual functions in neuropsychiatric disorders. Little is known about the genetic predisposition to neurodegenerative and neuroproliferative properties of cytokine genes. In this study the potential dual role of several IL-6 polymorphisms in brain morphology is investigated. Methodology: In a large sample of healthy individuals (N = 303), associations between genetic variants of IL-6 (rs1800795; rs1800796, rs2069833, rs2069840) and brain volume (gray matter volume) were analyzed using voxel-based morphometry (VBM). Selection of single nucleotide polymorphisms (SNPs) followed a tagging SNP approach (e.g., Stampa algorigthm), yielding a capture 97.08% of the variation in the IL-6 gene using four tagging SNPs. Principal findings/results: In a whole-brain analysis, the polymorphism rs1800795 (−174 C/G) showed a strong main effect of genotype (43 CC vs. 150 CG vs. 100 GG; x = 24, y = −10, z = −15; F(2,286) = 8.54, puncorrected = 0.0002; pAlphaSim-corrected = 0.002; cluster size k = 577) within the right hippocampus head. Homozygous carriers of the G-allele had significantly larger hippocampus gray matter volumes compared to heterozygous subjects. None of the other investigated SNPs showed a significant association with grey matter volume in whole-brain analyses. Conclusions/significance: These findings suggest a possible neuroprotective role of the G-allele of the SNP rs1800795 on hippocampal volumes. Studies on the role of this SNP in psychiatric populations and especially in those with an affected hippocampus (e.g., by maltreatment, stress) are warranted.Bernhard T Baune, Carsten Konrad, Dominik Grotegerd, Thomas Suslow, Eva Birosova, Patricia Ohrmann, Jochen Bauer, Volker Arolt, Walter Heindel, Katharina Domschke, Sonja Schöning, Astrid V Rauch, Christina Uhlmann, Harald Kugel and Udo Dannlowsk
Albiglutide, a Long Lasting Glucagon-Like Peptide-1 Analog, Protects the Rat Heart against Ischemia/Reperfusion Injury: Evidence for Improving Cardiac Metabolic Efficiency
BACKGROUND: The cardioprotective effects of glucagon-like peptide-1 (GLP-1) and analogs have been previously reported. We tested the hypothesis that albiglutide, a novel long half-life analog of GLP-1, may protect the heart against I/R injury by increasing carbohydrate utilization and improving cardiac energetic efficiency. METHODS/PRINCIPAL FINDINGS: Sprague-Dawley rats were treated with albiglutide and subjected to 30 min myocardial ischemia followed by 24 h reperfusion. Left ventricle infarct size, hemodynamics, function and energetics were determined. In addition, cardiac glucose disposal, carbohydrate metabolism and metabolic gene expression were assessed. Albiglutide significantly reduced infarct size and concomitantly improved post-ischemic hemodynamics, cardiac function and energetic parameters. Albiglutide markedly increased both in vivo and ex vivo cardiac glucose uptake while reducing lactate efflux. Analysis of metabolic substrate utilization directly in the heart showed that albiglutide increased the relative carbohydrate versus fat oxidation which in part was due to an increase in both glucose and lactate oxidation. Metabolic gene expression analysis indicated upregulation of key glucose metabolism genes in the non-ischemic myocardium by albiglutide. CONCLUSION/SIGNIFICANCE: Albiglutide reduced myocardial infarct size and improved cardiac function and energetics following myocardial I/R injury. The observed benefits were associated with enhanced myocardial glucose uptake and a shift toward a more energetically favorable substrate metabolism by increasing both glucose and lactate oxidation. These findings suggest that albiglutide may have direct therapeutic potential for improving cardiac energetics and function
Oral vs. pharyngeal dysphagia: surface electromyography randomized study
<p>Abstract</p> <p>Background</p> <p>A clear differential diagnosis between oral and pharyngeal dysphagia remains an unsolved problem. Disorders of the oral cavity are frequently overlooked when dysphagia/odybophagia complaints are assessed. Surface electromyographic (sEMG) studies were performed on randomly assigned patients with oral and pharyngeal pathology to evaluate their dysphagia complaints for the sake of differential diagnosis.</p> <p>Methods</p> <p>Parameters evaluated during swallowing for patients after dental surgery (1: n = 62), oral infections (2: n = 49), acute tonsillitis (3: n = 66) and healthy controls (4: n = 50) included timing and amplitude of sEMG activity of masseter, infrahyoid and submental muscles.</p> <p>Results</p> <p>The duration of swallows and drinking periods was significantly increased in dental patients and was normal in patients with tonsillitis. The electric activity of masseter was significantly lower in Groups 1 and 2 in comparison with the patients with tonsillitis and controls. The submental and infrahyoid activity was normal in dental patients but infrahyoid activity in patients with tonsillitis was high.</p> <p>Conclusion</p> <p>Dysphagia following dental surgery or oral infections does not affect pharynx and submental muscles and has clear sEMG signs: increased duration of a single swallow, longer drinking time, low activity of the masseter, and normal range of submental activity. Patients with tonsillitis present hyperactivity of infrahyoid muscles. These data could be used for evaluation of symptoms when differential dental/ENT diagnosis is needed.</p
- …