1,563 research outputs found
Controlled dephasing of a quantum dot in the Kondo regime
Kondo correlation in a spin polarized quantum dot (QD) results from the
dynamical formation of a spin singlet between the dot's net spin and a Kondo
cloud of electrons in the leads, leading to enhanced coherent transport through
the QD. We demonstrate here significant dephasing of such transport by coupling
the QD and its leads to potential fluctuations in a near by 'potential
detector'. The qualitative dephasing is similar to that of a QD in the Coulomb
Blockade regime in spite of the fact that the mechanism of transport is quite
different. A much stronger than expected suppression of coherent transport is
measured, suggesting that dephasing is induced mostly in the 'Kondo cloud' of
electrons within the leads and not in the QD.Comment: to be published in PR
Federated Statistical Analysis: Non-parametric Testing and Quantile Estimation
The age of big data has fueled expectations for accelerating learning. The
availability of large data sets enables researchers to achieve more powerful
statistical analyses and enhances the reliability of conclusions, which can be
based on a broad collection of subjects. Often such data sets can be assembled
only with access to diverse sources; for example, medical research that
combines data from multiple centers in a federated analysis. However these
hopes must be balanced against data privacy concerns, which hinder sharing raw
data among centers. Consequently, federated analyses typically resort to
sharing data summaries from each center. The limitation to summaries carries
the risk that it will impair the efficiency of statistical analysis procedures.
In this work we take a close look at the effects of federated analysis on two
very basic problems, nonparametric comparison of two groups and quantile
estimation to describe the corresponding distributions. We also propose a
specific privacy-preserving data release policy for federated analysis with the
-anonymity criterion, which has been adopted by the Medical Informatics
Platform of the European Human Brain Project. Our results show that, for our
tasks, there is only a modest loss of statistical efficiency
Toward a Scholarship of Teaching and Learning in Educational Development
Educational development traditionally has been a practice-based field. We propose that as a profession we adopt the methods of the scholarship of teaching and learning (SoTL), so often shared with our clients, in order to look through a scholarly lens at the outcomes of our own practice. Using SoTL approaches in our work would deepen the research literature in our field and improve the effectiveness of decisions we make about where to spend limited time and resources. In this chapter, we explore what it might mean for individual developers, and for our professional community, to apply SoTL methods to our practice
Combined effects of extrinsic and intrinsic factors on otolith chemistry: Implications for environmental reconstructions
Otolith chemistry is widely used to understand patterns of fish movement and habitat use, with significant progress made in understanding the influence of environmental factors on otolith elemental uptake. However, few studies consider the interactive effect that environmental and genetic influences have on otolith chemistry. This study assessed the influence of salinity, temperature, and genetics on the incorporation of three key elements (strontium (Sr), barium (Ba), and magnesium (Mg)) into the otoliths of two discrete stocks of mulloway (Argyrosomus japonicus) fingerlings reared in captivity. Elemental analysis via laser ablation inductively coupled – plasma mass spectrometry found that stock (genetics) had a significant interactive effect on otolith Sr:Ca (salinity × temperature × stock) and Ba:Ca (salinity × stock), but did not affect Mg:Ca incorporation. Mg:Ca showed a positive relationship with temperature for both stocks. The incorporation of some elements into the otoliths of fish is the result of complex interactions between extrinsic and intrinsic factors. These findings highlight the necessity to also consider stock along with environmental variables when using trace elemental signatures to reconstruct the environmental histories of fish.Thomas C. Barnes, Bronwyn M. Gillander
Does time equal vision in the acute treatment of a cohort of AQP4 and MOG optic neuritis?
Objective To investigate whether visual disability which is known to accumulate by poor recovery from optic neuritis (ON) attacks can be lessened by early treatment, we investigated whether the time from symptom onset to high-dose IV methylprednisolone (IVMP) affected visual recovery. Methods: A retrospective study was performed in a consecutive cohort of patients following their first aquaporin-4 (AQP4)-IgG or myelin oligodendrocyte glycoprotein (MOG)-IgG-ON. Best-corrected visual acuity (BCVA) in ON eyes at 3 months (BCVA3mo) was correlated with time to IVMP (days). In cases of bilateral ON, 1 eye was randomly selected. Results: A total of 29 of 37 patients had ON (27 AQP4-seropositive neuromyelitis optica spectrum disorder [NMOSD] and 9 MOG-IgG-ON), 2 of whom refused treatment. Of the 27 patients included, 10 presented later than 7 days from onset. The median BCVA3mo of patients treated >7 days was 20/100 (interquartile range 20/100–20/200). Patients treated >7 days had an OR of 5.50 (95% CI 0.88–34.46, p = 0.051) of failure to regain 0.0 logMAR vision (20/20) and an OR of 10.0 (95% CI 1.39–71.9) of failure to regain 0.2 logMAR vision (20/30) (p = 0.01) compared with patients treated within 7 days. ROC analysis revealed that the optimal criterion of delay in IVMP initiation was ≤4 days, with a sensitivity and specificity of 71.4% and 76.9%, respectively. Conclusions: In this retrospective study of ON with AQP4 and MOG-IgG, even a 7-day delay in IVMP initiation was detrimental to vision. These results highlight the importance of early treatment for the long-term visual recovery in this group of patients. A prospective, multicenter study of the effects of timing of IVMP is currently underway. Classification of evidence: This study provides Class IV evidence that hyperacute treatment of AQP4 and MOG-ON with IVMP increases the chance for good visual recovery (20/20 vision) and that even a greater than 7-day delay in treatment is associated with a higher risk for poor visual recovery
Heme Oxygenase-1 Expression Affects Murine Abdominal Aortic Aneurysm Progression.
Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme degradation, is a cytoprotective enzyme upregulated in the vasculature by increased flow and inflammatory stimuli. Human genetic data suggest that a diminished HO-1 expression may predispose one to abdominal aortic aneurysm (AAA) development. In addition, heme is known to strongly induce HO-1 expression. Utilizing the porcine pancreatic elastase (PPE) model of AAA induction in HO-1 heterozygous (HO-1+/-, HO-1 Het) mice, we found that a deficiency in HO-1 leads to augmented AAA development. Peritoneal macrophages from HO-1+/- mice showed increased gene expression of pro-inflammatory cytokines, including MCP-1, TNF-alpha, IL-1-beta, and IL-6, but decreased expression of anti-inflammatory cytokines IL-10 and TGF-beta. Furthermore, treatment with heme returned AAA progression in HO-1 Het mice to a wild-type profile. Using a second murine AAA model (Ang II-ApoE-/-), we showed that low doses of the HMG-CoA reductase inhibitor rosuvastatin can induce HO-1 expression in aortic tissue and suppress AAA progression in the absence of lipid lowering. Our results support those studies that suggest that pleiotropic statin effects might be beneficial in AAA, possibly through the upregulation of HO-1. Specific targeted therapies designed to induce HO-1 could become an adjunctive therapeutic strategy for the prevention of AAA disease
Fano Effect in a Few-Electron Quantum Dot
We have studied the Fano effect in a few-electron quantum dot side-coupled to
a quantum wire. The conductance of the wire, which shows an ordinal
staircase-like quantization without the dot, is modified through the
interference (the Fano effect) and the charging effects. These effects are
utilized to verify the exhaustion of electrons in the dot. The "addition energy
spectrum" of the dot shows a shell structure, indicating that the electron
confinement potential is fairly circular. A rapid sign inversion of the Fano
parameter on the first conductance plateau with the change of the wire gate
voltage has been observed, and explained by introducing a finite width of
dot-wire coupling.Comment: 11 pages, 7 figure
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