Electromagnetically induced transparency and four-wave mixing in a cold atomic ensemble with large optical depth

We report on the delay of optical pulses using electromagnetically induced transparency in an ensemble of cold atoms with an optical depth exceeding 500. To identify the regimes in which four-wave mixing impacts on EIT behaviour, we conduct the experiment in both rubidium 85 and rubidium 87. Comparison with theory shows excellent agreement in both isotopes. In rubidium 87, negligible four-wave mixing was observed and we obtained one pulse-width of delay with 50% efficiency. In rubidium 85, four-wave-mixing contributes to the output. In this regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing temporally multimode delay, which we demonstrate by compressing two pulses into the memory medium.Comment: 8 pages, 6 figure

Gradient echo quantum memory in warm atomic vapor

Video Article - http://www.jove.com/video/50552Gradient echo memory (GEM) is a protocol for storing optical quantum states of light in atomic ensembles. The primary motivation for such a technology is that quantum key distribution (QKD), which uses Heisenberg uncertainty to guarantee security of cryptographic keys, is limited in transmission distance. The development of a quantum repeater is a possible path to extend QKD range, but a repeater will need a quantum memory. In our experiments we use a gas of rubidium 87 vapor that is contained in a warm gas cell. This makes the scheme particularly simple. It is also a highly versatile scheme that enables in-memory refinement of the stored state, such as frequency shifting and bandwidth manipulation. The basis of the GEM protocol is to absorb the light into an ensemble of atoms that has been prepared in a magnetic field gradient. The reversal of this gradient leads to rephasing of the atomic polarization and thus recall of the stored optical state. We will outline how we prepare the atoms and this gradient and also describe some of the pitfalls that need to be avoided, in particular four-wave mixing, which can give rise to optical gain.Olivier Pinel, Mahdi Hosseini, Ben M. Sparkes, Jesse L. Everett, Daniel Higginbottom, Geoff T. Campbell, Ping Koy Lam, Ben C. Buchle

An ethnographic investigation of maternity healthcare experience of immigrants in rural and urban Alberta, Canada

Background: Canada is among the top immigrant-receiving nations in the world. Immigrant populations may face structural and individual barriers in the access to and navigation of healthcare services in a new country. The aims of the study were to (1) generate new understanding of the processes that perpetuate immigrant disadvantages in maternity healthcare, and (2) devise potential interventions that might improve maternity experiences and outcomes for immigrant women in Canada. Methods: The study utilized a qualitative research approach that focused on ethnographic research design and data analysis contextualized within theories of organizational behaviour and critical realism. Data were collected over 2.5 years using focus groups and in-depth semistructured interviews with immigrant women (n = 34), healthcare providers (n = 29), and social service providers (n = 23) in a Canadian province. Purposive samples of each subgroup were generated, and recruitment and data collection – including interpretation and verification of translations – were facilitated through the hiring of community researchers and collaborations with key informants. Results: The findings indicate that (a) communication difficulties, (b) lack of information, (c) lack of social support (isolation), (d) cultural beliefs, e) inadequate healthcare services, and (f) cost of medicine/services represent potential barriers to the access to and navigation of maternity services by immigrant women in Canada. Having successfully accessed and navigated services, immigrant women often face additional challenges that influence their level of satisfaction and quality of care, such as lack of understanding of the informed consent process, lack of regard by professionals for confidential patient information, short consultation times, short hospital stays, perceived discrimination/stereotyping, and culture shock. Conclusions: Although health service organizations and policies strive for universality and equality in service provision, personal and organizational barriers can limit care access, adequacy, and acceptability for immigrant women. A holistic healthcare approach must include health informational packages available in different languages/media. Health care professionals who care for diverse populations must be provided with training in cultural competence, and monitoring and evaluation programs to ameliorate personal and systemic discrimination

Relationships of Brain Cholesterol and Cholesterol Biosynthetic Enzymes to Alzheimer’s Pathology and Dementia in the CFAS Population-Derived Neuropathology Cohort

Altered cholesterol metabolism is implicated in brain ageing and Alzheimer's disease. We examined whether key genes regulating cholesterol metabolism and levels of brain cholesterol are altered in dementia and Alzheimer's disease neuropathological change (ADNC). Temporal cortex (n = 99) was obtained from the Cognitive Function and Ageing Study. Expression of the cholesterol biosynthesis rate-limiting enzyme HMG-CoA reductase (HMGCR) and its regulator, SREBP2, were detected using immunohistochemistry. Expression of HMGCR, SREBP2, CYP46A1 and ABCA1 were quantified by qPCR in samples enriched for astrocyte and neuronal RNA following laser-capture microdissection. Total cortical cholesterol was measured using the Amplex Red assay. HMGCR and SREBP2 proteins were predominantly expressed in pyramidal neurones, and in glia. Neuronal HMGCR did not vary with ADNC, oxidative stress, neuroinflammation or dementia status. Expression of HMGCR neuronal mRNA decreased with ADNC (p = 0.022) and increased with neuronal DNA damage (p = 0.049), whilst SREBP2 increased with ADNC (p = 0.005). High or moderate tertiles for cholesterol levels were associated with increased dementia risk (OR 1.44, 1.58). APOE ε4 allele was not associated with cortical cholesterol levels. ADNC is associated with gene expression changes that may impair cholesterol biosynthesis in neurones but not astrocytes, whilst levels of cortical cholesterol show a weak relationship to dementia status

The transitioning experiences of internationally-educated nurses into a Canadian health care system: A focused ethnography

<p>Abstract</p> <p>Background</p> <p>Beyond well-documented credentialing issues, internationally-educated nurses (IENs) may need considerable support in transitioning into new social and health care environments. This study was undertaken to gain an understanding of transitioning experiences of IENs upon relocation to Canada, while creating policy and practice recommendations applicable globally for improving the quality of transitioning and the retention of IENs.</p> <p>Methods</p> <p>A focused ethnography of newly-recruited IENs was conducted, using individual semi-structured interviews at both one-to-three months (Phase 1) and nine-to-twelve months post-relocation (Phase 2). A purposive sample of IENs was recruited during their orientation at a local college, to a health authority within western Canada which had recruited them for employment throughout the region. The interviews were recorded and transcribed, and data was managed using qualitative analytical software. Data analysis was informed by Roper and Shapira's framework for focused ethnography.</p> <p>Results</p> <p>Twenty three IENs consented to participate in 31 interviews. All IENs which indicated interest during their orientation sessions consented to the interviews, yet 14 did not complete the Phase 2 interview due to reorganization of health services and relocation. The ethno-culturally diverse group had an average age of 36.4 years, were primarily educated to first degree level or higher, and were largely (under) employed as "Graduate Nurses". Many IENs reported negative experiences related to their work contract and overall support upon arrival. There were striking differences in nursing practice and some experiences of perceived discrimination. The primary area of discontentment was the apparent communication breakdown at the recruitment stage with subsequent discrepancy in expected professional role and financial reimbursement.</p> <p>Conclusions</p> <p>Explicit and clear communication is needed between employers and recruitment agencies to avoid employment contract misunderstandings and to enable clear interpretation of the credentialing processes. Pre-arrival orientation of IENs including health care communications should be encouraged and supported by the recruiting institution. Moreover, employers should provide more structured and comprehensive workplace orientation to IENs with consistent preceptorship. Similar to findings of many other studies, diversity should be valued and incorporated into the professional culture by nurse managers.</p

Waveguide-integrated silicon T centres

The performance of modular, networked quantum technologies will be strongly dependent upon the quality of their quantum light-matter interconnects. Solid-state colour centres, and in particular T centres in silicon, offer competitive technological and commercial advantages as the basis for quantum networking technologies and distributed quantum computing. These newly rediscovered silicon defects offer direct telecommunications-band photonic emission, long-lived electron and nuclear spin qubits, and proven native integration into industry-standard, CMOS-compatible, silicon-on-insulator (SOI) photonic chips at scale. Here we demonstrate further levels of integration by characterizing T centre spin ensembles in single-mode waveguides in SOI. In addition to measuring long spin T_1 times, we report on the integrated centres' optical properties. We find that the narrow homogeneous linewidth of these waveguide-integrated emitters is already sufficiently low to predict the future success of remote spin-entangling protocols with only modest cavity Purcell enhancements. We show that further improvements may still be possible by measuring nearly lifetime-limited homogeneous linewidths in isotopically pure bulk crystals. In each case the measured linewidths are more than an order of magnitude lower than previously reported and further support the view that high-performance, large-scale distributed quantum technologies based upon T centres in silicon may be attainable in the near term

Factors influencing the practice of new graduate nurses : a focused ethnography of acute care settings

Aim: To explore the influence of an acute care setting on competency deployment of new graduate nurses (NGNs) from a competency -based undergraduate programme . Background: In the last 15 years, nursing education has shifted to competency -based education (CBE). Few studies have focused on how NGNs from these reformed programmes use the competencies they have developed. To be paradigmatically coherent with the nature of a competence, studies should also examine how context influences nursing practice and competency deployment. Design: A focused ethnography of three acute care units from one academic hospital in Canada. Methods: Purposive and snowball sampling strategies were used to recruit 19 participants: NGNs (n = 4), nurse preceptors (n = 2), clinical nurse specialists (n = 9) , and nurse managers (n = 4). Data were collected through individual interviews, focus groups , observation and documentation. Data were analysed according to Roper and Shapira’s (2000) ethnographic nursing analysis framework. Results: Organizational and individual factors were identified as influencing NGNs ’ competenc y deployment. Organizational factors are orientation, stability, workload, and the scientific culture of the unit. Personal factors have been linked to groups of professionals: for NGNs, personality and clinical placements during their initial education; for nurses working with NGNs, to be role models, to promote integration and to denounce bullying; and for other health professionals, to recognize nursing expertise. Conclusion: One way to s mooth the transition from academic to clinical settings for NGNs is by offering transition or orientation programmes that will provide them with stability and a reduced workload, allowing them to progressively deploy their competencies. Relevance to clinical practice: Organizational and individual factors influence how new graduate nurses deploy their competencies. Clinical educators and nurse managers can help new nurses by acting on these factors