Doppler-Induced Dynamics of Fields in Fabry-Perot Cavities with Suspended Mirrors

The Doppler effect in Fabry-Perot cavities with suspended mirrors is analyzed. Intrinsically small, the Doppler shift accumulates in the cavity and becomes comparable to or greater than the line-width of the cavity if its finesse is high or its length is large. As a result, damped oscillations of the cavity field occur when one of the mirrors passes a resonance position. A formula for this transient is derived. It is shown that the frequency of the oscillations is equal to the accumulated Doppler shift and the relaxation time of the oscillations is equal to the storage time of the cavity. Comparison of the predicted and the measured Doppler shift is discussed, and application of the analytical solution for measurement of the mirror velocity is described

Hydrogen peroxide production in a pilot-scale microbial electrolysis cell

The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.btre.2018.e00276 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/A pilot-scale dual-chamber microbial electrolysis cell (MEC) equipped with a carbon gas-diffusion cathode was evaluated for H2O2 production using acetate medium as the electron donor. To assess the effect of cathodic pH on H2O2 yield, the MEC was tested with an anion exchange membrane (AEM) and a cation exchange membrane (CEM), respectively. The maximum current density reached 0.94–0.96 A/m2 in the MEC at applied voltage of 0.35–1.9 V, regardless of membranes. The highest H2O2 conversion efficiency was only 7.2 ± 0.09% for the CEM-MEC. This low conversion would be due to further H2O2 reduction to H2O on the cathode or H2O2 decomposition in bulk liquid. This low H2O2 conversion indicates that large-scale MECs are not ideal for production of concentrated H2O2 but could be useful for a sustainable in-situ oxidation process in wastewater treatment.Ontario Early Researcher Awar

Increased Cortical Cerebral Blood Flow in Asymptomatic Human Immunodeficiency Virus-Infected Subjects

Human Immunodeficiency Virus (HIV) infected individuals are at high risk for ischemic stroke. To investigate the physiological basis for this risk, we used magnetic resonance imaging (MRI) to measure oxygen extraction fraction (OEF) and cerebral blood flow (CBF) in treatment naïve asymptomatic HIV-infected subjects and controls

Building up spacetime with quantum entanglement

In this essay, we argue that the emergence of classically connected spacetimes is intimately related to the quantum entanglement of degrees of freedom in a non-perturbative description of quantum gravity. Disentangling the degrees of freedom associated with two regions of spacetime results in these regions pulling apart and pinching off from each other in a way that can be quantified by standard measures of entanglement.Comment: Gravity Research Foundation essay, 7 pages, LaTeX, 5 figure

Daytime Sleep Enhances Consolidation of the Spatial but Not Motoric Representation of Motor Sequence Memory

Motor sequence learning is known to rely on more than a single process. As the skill develops with practice, two different representations of the sequence are formed: a goal representation built under spatial allocentric coordinates and a movement representation mediated through egocentric motor coordinates. This study aimed to explore the influence of daytime sleep (nap) on consolidation of these two representations. Through the manipulation of an explicit finger sequence learning task and a transfer protocol, we show that both allocentric (spatial) and egocentric (motor) representations of the sequence can be isolated after initial training. Our results also demonstrate that nap favors the emergence of offline gains in performance for the allocentric, but not the egocentric representation, even after accounting for fatigue effects. Furthermore, sleep-dependent gains in performance observed for the allocentric representation are correlated with spindle density during non-rapid eye movement (NREM) sleep of the post-training nap. In contrast, performance on the egocentric representation is only maintained, but not improved, regardless of the sleep/wake condition. These results suggest that motor sequence memory acquisition and consolidation involve distinct mechanisms that rely on sleep (and specifically, spindle) or simple passage of time, depending respectively on whether the sequence is performed under allocentric or egocentric coordinates

The control of graphene double-layer formation in copper-catalyzed chemical vapor deposition

The growth of graphene during Cu-catalyzed chemical vapor deposition was studied using 12CH4 and 13CH4 precursor gasses. We suggest that the growth begins by the formation of a multilayer cluster. This seed increases its size but the growth speed of a particular layer depends on its proximity to the copper surface. The layer closest to the substrate grows fastest and thus further limits the growth rate of the upper layers. Nevertheless, the growth of the upper layers continues until the copper surface is completely blocked. It is shown that the upper layers can be removed by modification of the conditions of the growth by hydrogen etching.Comment: 17 pages, 4 figure

Sequence determinants of breakpoint location during HIV-1 intersubtype recombination

Retroviral recombination results from strand switching, during reverse transcription, between the two copies of genomic RNA present in the virus. We analysed recombination in part of the envelope gene, between HIV-1 subtype A and D strains. After a single infection cycle, breakpoints clustered in regions corresponding to the constant portions of Env. With some exceptions, a similar distribution was observed after multiple infection cycles, and among recombinant sequences in the HIV Sequence Database. We compared the experimental data with computer simulations made using a program that only allows recombination to occur whenever an identical base is present in the aligned parental RNAs. Experimental recombination was more frequent than expected on the basis of simulated recombination when, in a region spanning 40 nt from the 5′ border of a breakpoint, no more than two discordant bases between the parental RNAs were present. When these requirements were not fulfilled, breakpoints were distributed randomly along the RNA, closer to the distribution predicted by computer simulation. A significant preference for recombination was also observed for regions containing homopolymeric stretches. These results define, for the first time, local sequence determinants for recombination between divergent HIV-1 isolates

Plugging a hole and lightening the burden: A process evaluation of a practice education team

Aim: To investigate the perceptions of clinical and senior managers about the role of Practice Educators employed in one acute hospital in the UK. Background: Producing nurses who are fit for practice, purpose and academic award is a key issue for nurse education partnership providers in the UK. Various new models for practice learning support structures and new roles within health care institutions have been established. To sustain funding and policy support for these models, there is a need for evaluation research. Design: A process evaluation methodology was employed to determine the current value of a practice education team and to provide information to guide future direction. Methods: Data were collected through semi-structured telephone interviews using a previously designed schedule. All senior nurse managers (N=5) and a purposive sample of clinical managers (n=13) who had personal experience of and perceptions about the role of practice educators provided the data. Interview notes were transcribed, coded and a thematic framework devised to present the results. Results: A number of key themes emerged including: qualities needed for being a successful practice educator; visibility and presence of practice educators; providing a link with the university; ‘plugging a hole’ in supporting learning needs; providing relief to practitioners in dealing with ‘the burden of students’; alleviating the ‘plight of students’; and effects on student attrition. Conclusions: Findings provided evidence for the continued funding of the practice educator role with improvements to be made in dealing with stakeholder expectations and outcomes. Relevance to clinical practice: In the UK, there still remain concerns about the fitness for practice of newly registered nurses, prompting a recent national consultation by the professional regulating body. Despite fiscal pressures, recommendations for further strengthening of all systems that will support the quality of practice learning may continue to sustain practice learning support roles