175 research outputs found
Real-time 10Gbps Polarization Independent Quasicoherent Receiver for NG-PON2 Access Networks
In this paper, we propose and test experimentally a real-time 10 Gbps polarization independent quasicoherent receiver for NG-PON2 access networks. The proposed 10 Gbps quasicoherent receiver exhibits a sensitivity of -35.2 dBm after 40 km SSMF transmission with a commercial generic EML as transmitter. This sensitivity means a 14.9 dB improvement over a direct detection scheme with a photodiode after 40 km SSMF transmission. Therefore, the use of the proposed 10 Gbps quasicoherent receiver with the tested EML will provide a power budget of 34.76 dB (class E1) and a splitting ratio of 128 after the 40 km SSMF transmission. Finally, the proposed 10 Gbps quasicoherent receiver allows a colorless and optical filterless operation because wavelength selection is done by tuning the local oscillator wavelength and using electrical intermediate frequency filtering. IEE
Seasonal and diurnal variations in AMPERE observations of the Birkeland currents compared to modeled results
We reduce measurements made by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) to give the total Birkeland (field-aligned) current flowing in both hemispheres in monthly and hourly bins. We analyze these totals using 6 years of data (2010–2015) to examine solar zenith angle-driven variations in the total Birkeland current flowing in both hemispheres, simultaneously, for the first time. A diurnal variation is identified in the total Birkeland current flowing, consistent with variations in the solar zenith angle. A seasonal variation is also identified, with more current flowing in the Northern (Southern) Hemisphere during Bartels rotations in northern (southern) summer. For months close to equinox, more current is found to flow in the Northern Hemisphere, contrary to our expectations. We also conduct the first test of the Milan (2013) model for estimating Birkeland current magnitudes, with modifications made to account for solar contributions to ionospheric conductance based on the observed variation of the Birkeland currents with season and time of day. The modified model, using the value of ?D averaged by Bartels rotation (scaled by 1.7), is found to agree with the observed AMPERE currents, with a correlation of 0.87 in the Northern Hemisphere and 0.86 in the Southern Hemisphere. The improvement over the correlation with dayside reconnection rate is demonstrated to be a significant improvement to the model. The correlation of the residuals is found to be consistent with more current flowing in the Northern Hemisphere. This new observation of systematically larger current flowing in the Northern Hemisphere is discussed in the context of previous results which suggest that the Northern Hemisphere may react more strongly to dayside reconnection than the Southern Hemisphere
Optimal outcomes and women's positive pregnancy experience: a comparison between the World Health Organization guideline and recommendations in European national antenatal care guidelines.
BACKGROUND: The publication of the World Health Organization (WHO) recommendations on antenatal care in 2016 introduced the perspective of women as a necessary component of clinical guidelines in maternity care. WHO highlights the crucial role played by evidence-based recommendations in promoting and supporting normal birth processes and a positive experience of pregnancy. This paper aims to explore and critically appraise recommendations of national antenatal care guidelines across European countries in comparison with the WHO guideline. METHODS: We collected guidelines from country partners of the EU COST Action IS1405. Components of the documents structure and main recommendations within and between them were compared and contrasted with the WHO guideline on antenatal care with a particular interest in exploring whether and how women's experience was included in the recommendations. RESULTS: Eight out of eleven countries had a single national guideline on antenatal care while three countries did not. National guidelines mostly focused on care of healthy women with a straightforward pregnancy. The level of concordance between the national and the WHO recommendations varied along a continuum from almost total concordance to almost total dissonance. Women's views and experiences were accounted for in some guidelines, but mostly not placed at the same level of importance as clinical items. CONCLUSIONS: Findings outline convergences and divergences with the WHO recommendations. They highlight the need for considering women's views more in the development of evidence-based recommendations and in practice for positive impacts on perinatal health at a global level, and on the experiences of each family
How much synthetic oxytocin is infused during labour? A review and analysis of regimens used in 12 countries.
OBJECTIVE: To compare synthetic oxytocin infusion regimens used during labour, calculate the International Units (IU) escalation rate and total amount of IU infused over eight hours. DESIGN: Observational study. SETTING: Twelve countries, eleven European and South Africa. SAMPLE: National, regional or institutional-level regimens on oxytocin for induction and augmentation labour. METHODS: Data on oxytocin IU dose, infusion fluid amount, start dose, escalation rate and maximum dose were collected. Values for each regimen were converted to IU in 1000ml diluent. One IU corresponded to 1.67μg for doses provided in grams/micrograms. IU hourly dose increase rates were based on escalation frequency. Cumulative doses and total IU amount infused were calculated by adding the dose administered for each previous hour. Main Outcome Measures Oxytocin IU dose infused. RESULTS: Data were obtained on 21 regimens used in 12 countries. Details on the start dose, escalation interval, escalation rate and maximum dose infused were available from 16 regimens. Starting rates varied from 0.06 IU/hour to 0.90 IU/hour, and the maximum dose rate varied from 0.90 IU/hour to 3.60 IU/hour. The total amount of IU oxytocin infused, estimated over eight hours, ranged from 2.38 IU to 27.00 IU, a variation of 24.62 IU and an 11-fold difference. CONCLUSION: Current variations in oxytocin regimens for induction and augmentation of labour are inexplicable. It is crucial that the appropriate minimum infusion regimen is administered because synthetic oxytocin is a potentially harmful medication with serious consequences for women and babies when inappropriately used. Estimating the total amount of oxytocin IU received by labouring women, alongside the institution's mode of birth and neonatal outcomes, may deepen our understanding and be the way forward to identifying the optimal infusion regimen
Advances in ab-initio theory of Multiferroics. Materials and mechanisms: modelling and understanding
Within the broad class of multiferroics (compounds showing a coexistence of
magnetism and ferroelectricity), we focus on the subclass of "improper
electronic ferroelectrics", i.e. correlated materials where electronic degrees
of freedom (such as spin, charge or orbital) drive ferroelectricity. In
particular, in spin-induced ferroelectrics, there is not only a {\em
coexistence} of the two intriguing magnetic and dipolar orders; rather, there
is such an intimate link that one drives the other, suggesting a giant
magnetoelectric coupling. Via first-principles approaches based on density
functional theory, we review the microscopic mechanisms at the basis of
multiferroicity in several compounds, ranging from transition metal oxides to
organic multiferroics (MFs) to organic-inorganic hybrids (i.e. metal-organic
frameworks, MOFs)Comment: 22 pages, 9 figure
School dropout, problem behaviour and poor academic achievement : a longitudinal view of portuguese male offenders
This study examines school drop outs from the perspective of male adults
themselves through interviews with offenders currently serving sentences. Participants
were 10 Portuguese male inmates, between the ages of 19 and 46 years of age,
incarcerated in two prison facilities of the Azores. Qualitative and interpretative methods
were carried out using a semi-structured in-depth individual interview that was audiorecorded
and conducted on the basis of a list of topics. Interview transcripts and thematic
analysis were used in data treatment and analysis. The findings primarily indicate that
poor academic achievement and emotional and behavioural difficulties of participants
played a particular role in early school drop out. The trajectories these individuals
followed within the education system presented problem behaviour, learning disabilities,
and/or foster care interventions. While school drop out circumstances were apparently
various, analysis showed that they were underpinned by three distinct sets of conditions
generally not addressed by the education system. The analysis of the triggering factors
and the maintenance dynamics of school drop outs indicated three distinct types:
retention/absenteeism, life turning points and positive resolution. Implications for
secondary prevention and screening practices are discussed.FCT (SFRH/ BD/ 44245/ 2008)CIEC - unidade de investigação 317 da FC
Predicting risk among non-respondents in prospective studies
Potential non-response bias was investigated in a follow-up study of 2,011 chronically disabled patients. 82.5% and 73.3% of the study subjects responded to self-administered mail questionnaires respectively at 6-month and 1-year follow-up. Information on employment status, the outcome of interest, of approximately 90% of the non-respondents was obtained from indirect sources. Employment rate was lower among the non-respondents than the respondents. Non-response was associated with age, social class, previous employment record, and the type of disability; but none of these characteristics were associated with the outcome. Out of the five known independent risk factors for unemployment, only one (incompletion of rehabilitation course) was associated with non-response. The employment rate among the respondents was also assessed according to the delay in response, that is the number of reminders sent to achieve response. The outcome among- the late respondents was similar to that among the nonrespondents. These data suggest that (a) risk estimates may be biased even when the response rate is greater than 80%, (b) the prevalence of risk factors among non-respondents may not indicate the presence or the degree of non-response bias, but (c) reliable estimates can be obtained from extrapolations of the rates among the respondents according to the delay in response.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42663/1/10654_2004_Article_BF00152716.pd
- …