Ultrafast optical control using the Kerr nonlinearity in hydrogenated amorphous silicon microcylindrical resonators

Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies

Effect of core size on nonlinear transmission in silicon optical fibers

The nonlinear transmission properties of two hydrogenated amorphous silicon fibers with core diameters of 5.7µm and 1.7µm are characterized. The measured Kerr nonlinearity, two-photon absorption and free-carrier parameters will be discussed in relation to device performance

Towards in-fiber silicon photonics

The state of the art of silicon optical fibers fabricated via the high pressure chemical deposition technique will be reviewed. The optical transmission properties of step index silicon optical fibers will be presented, including investigations of the nonlinearities that can be used for all-optical signal processing. In addition, alternative complex fiber geometries that permit sophisticated control of the propagating light will be introduced

Two-photon absorption and self-phase modulation in silicon optical fibers into the mid-infrared regime

Nonlinear transmission is investigated in a hydrogenated amorphous silicon optical fiber extending into the mid-infrared region. Low losses past the two-photon absorption edge allow for strong spectral broadening in this important wavelength regime

Computational Nuclear Physics and Post Hartree-Fock Methods

We present a computational approach to infinite nuclear matter employing Hartree-Fock theory, many-body perturbation theory and coupled cluster theory. These lectures are closely linked with those of chapters 9, 10 and 11 and serve as input for the correlation functions employed in Monte Carlo calculations in chapter 9, the in-medium similarity renormalization group theory of dense fermionic systems of chapter 10 and the Green's function approach in chapter 11. We provide extensive code examples and benchmark calculations, allowing thereby an eventual reader to start writing her/his own codes. We start with an object-oriented serial code and end with discussions on strategies for porting the code to present and planned high-performance computing facilities.Comment: 82 pages, to appear in Lecture Notes in Physics (Springer), "An advanced course in computational nuclear physics: Bridging the scales from quarks to neutron stars", M. Hjorth-Jensen, M. P. Lombardo, U. van Kolck, Editor

Entanglement, Bell Inequalities and Decoherence in Particle Physics

We demonstrate the relevance of entanglement, Bell inequalities and decoherence in particle physics. In particular, we study in detail the features of the ``strange'' $K^0 \bar K^0$ system as an example of entangled meson--antimeson systems. The analogies and differences to entangled spin--1/2 or photon systems are worked, the effects of a unitary time evolution of the meson system is demonstrated explicitly. After an introduction we present several types of Bell inequalities and show a remarkable connection to CP violation. We investigate the stability of entangled quantum systems pursuing the question how possible decoherence might arise due to the interaction of the system with its ``environment''. The decoherence is strikingly connected to the entanglement loss of common entanglement measures. Finally, some outlook of the field is presented.Comment: Lectures given at Quantum Coherence in Matter: from Quarks to Solids, 42. Internationale Universit\"atswochen f\"ur Theoretische Physik, Schladming, Austria, Feb. 28 -- March 6, 2004, submitted to Lecture Notes in Physics, Springer Verlag, 45 page

Complex relationships among personality traits, job characteristics, and work behaviors

The aim of the study was to investigate the additive, mediating, and moderating effects of personality traits and job characteristics on work behaviors. Job applicants (N = 161) completed personality questionnaires measuring extraversion, neuroticism, achievement motivation, and experience seeking. One and a half years later, supervisors rated the applicants' job performance, and the job incumbents completed questionnaires about skill variety, autonomy, and feedback, work stress, job satisfaction, work self-efficacy, and propensity to leave. LISREL was used to test 15 hypotheses. Perceived feedback mediated the relationship between achievement motivation and job performance. Extraversion predicted work self-efficacy and job satisfaction. Work stress mediated the relationship between neuroticism and job satisfaction. Job satisfaction and experience seeking were related to propensity to leave. Autonomy, skill variety, and feedback were related to job satisfaction

Antibiotic use for inpatient newborn care with suspected infection: EN-BIRTH multi-country validation study

Background An estimated 30 million neonates require inpatient care annually, many with life-threatening infections. Appropriate antibiotic management is crucial, yet there is no routine measurement of coverage. The Every Newborn Birth Indicators Research Tracking in Hospitals (EN-BIRTH) study aimed to validate maternal and newborn indicators to inform measurement of coverage and quality of care. This paper reports validation of reported antibiotic coverage by exit survey of mothers for hospitalized newborns with clinically-defined infections, including sepsis, meningitis, and pneumonia. Methods EN-BIRTH study was conducted in five hospitals in Bangladesh, Nepal, and Tanzania (July 2017–July 2018). Neonates were included based on case definitions to focus on term/near-term, clinically-defined infection syndromes (sepsis, meningitis, and pneumonia), excluding major congenital abnormalities. Clinical management was abstracted from hospital inpatient case notes (verification) which was considered as the gold standard against which to validate accuracy of women’s report. Exit surveys were conducted using questions similar to The Demographic and Health Surveys (DHS) approach for coverage of childhood pneumonia treatment. We compared survey-report to case note verified, pooled across the five sites using random effects meta-analysis. Results A total of 1015 inpatient neonates admitted in the five hospitals met inclusion criteria with clinically-defined infection syndromes. According to case note verification, 96.7% received an injectable antibiotic, although only 14.5% of them received the recommended course of at least 7 days. Among women surveyed (n = 910), 98.8% (95% CI: 97.8–99.5%) correctly reported their baby was admitted to a neonatal ward. Only 47.1% (30.1–64.5%) reported their baby’s diagnosis in terms of sepsis, meningitis, or pneumonia. Around three-quarters of women reported their baby received an injection whilst in hospital, but 12.3% reported the correct antibiotic name. Only 10.6% of the babies had a blood culture and less than 1% had a lumbar puncture. Conclusions Women’s report during exit survey consistently underestimated the denominator (reporting the baby had an infection), and even more so the numerator (reporting known injectable antibiotics). Admission to the neonatal ward was accurately reported and may have potential as a contact point indicator for use in household surveys, similar to institutional births. Strengthening capacity and use of laboratory diagnostics including blood culture are essential to promote appropriate use of antibiotics. To track quality of neonatal infection management, we recommend using inpatient records to measure specifics, requiring more research on standardised inpatient records

Kangaroo mother care: EN-BIRTH multi-country validation study

Background Kangaroo mother care (KMC) reduces mortality among stable neonates ≤2000 g. Lack of data tracking coverage and quality of KMC in both surveys and routine information systems impedes scale-up. This paper evaluates KMC measurement as part of the Every Newborn Birth Indicators Research Tracking in Hospitals (EN-BIRTH) study. Methods The EN-BIRTH observational mixed-methods study was conducted in five hospitals in Bangladesh, Nepal and Tanzania from 2017 to 2018. Clinical observers collected time-stamped data as gold standard for mother-baby pairs in KMC wards/corners. To assess accuracy, we compared routine register-recorded and women’s exit survey-reported coverage to observed data, using different recommended denominator options (≤2000 g and ≤ 2499 g). We analysed gaps in quality of provision and experience of KMC. In the Tanzanian hospitals, we assessed daily skin-to-skin duration/dose and feeding frequency. Qualitative data were collected from health workers and data collectors regarding barriers and enablers to routine register design, filling and use. Results Among 840 mother-baby pairs, compared to observed 100% coverage, both exit-survey reported (99.9%) and register-recorded coverage (92.9%) were highly valid measures with high sensitivity. KMC specific registers outperformed general registers. Enablers to register recording included perceptions of data usefulness, while barriers included duplication of data elements and overburdened health workers. Gaps in KMC quality were identified for position components including wearing a hat. In Temeke Tanzania, 10.6% of babies received daily KMC skin-to-skin duration/dose of ≥20 h and a further 75.3% received 12–19 h. Regular feeding ≥8 times/day was observed for 36.5% babies in Temeke Tanzania and 14.6% in Muhimbili Tanzania. Cup-feeding was the predominant assisted feeding method. Family support during admission was variable, grandmothers co-provided KMC more often in Bangladesh. No facility arrangements for other family members were reported by 45% of women at exit survey. Conclusions Routine hospital KMC register data have potential to track coverage from hospital KMC wards/corners. Women accurately reported KMC at exit survey and evaluation for population-based surveys could be considered. Measurement of content, quality and experience of KMC need consensus on definitions. Prioritising further KMC measurement research is important so that high quality data can be used to accelerate scale-up of high impact care for the most vulnerable

Identification of new susceptibility loci for osteoarthritis (arcOGEN):a genome-wide association study

To access publisher's full text version of this article. Please click on the hyperlink in Additional Links field.Osteoarthritis is the most common form of arthritis worldwide and is a major cause of pain and disability in elderly people. The health economic burden of osteoarthritis is increasing commensurate with obesity prevalence and longevity. Osteoarthritis has a strong genetic component but the success of previous genetic studies has been restricted due to insufficient sample sizes and phenotype heterogeneity. We undertook a large genome-wide association study (GWAS) in 7410 unrelated and retrospectively and prospectively selected patients with severe osteoarthritis in the arcOGEN study, 80% of whom had undergone total joint replacement, and 11,009 unrelated controls from the UK. We replicated the most promising signals in an independent set of up to 7473 cases and 42,938 controls, from studies in Iceland, Estonia, the Netherlands, and the UK. All patients and controls were of European descent. We identified five genome-wide significant loci (binomial test p≤5·0×10(-8)) for association with osteoarthritis and three loci just below this threshold. The strongest association was on chromosome 3 with rs6976 (odds ratio 1·12 [95% CI 1·08-1·16]; p=7·24×10(-11)), which is in perfect linkage disequilibrium with rs11177. This SNP encodes a missense polymorphism within the nucleostemin-encoding gene GNL3. Levels of nucleostemin were raised in chondrocytes from patients with osteoarthritis in functional studies. Other significant loci were on chromosome 9 close to ASTN2, chromosome 6 between FILIP1 and SENP6, chromosome 12 close to KLHDC5 and PTHLH, and in another region of chromosome 12 close to CHST11. One of the signals close to genome-wide significance was within the FTO gene, which is involved in regulation of bodyweight-a strong risk factor for osteoarthritis. All risk variants were common in frequency and exerted small effects. Our findings provide insight into the genetics of arthritis and identify new pathways that might be amenable to future therapeutic intervention.Arthritis Research UK 1803