Variations in Fertility - a Consequense of Other Factors Besides Love?

The purpose of this paper is to discuss possible explanations for the variation in the Swedish fertility rate. We are primarily interested in economic and social conditions and their impact on the total fertility rate between 1965 and 2003. The results from the study support a positive e¤ect on fertility from the female labour market participation and child allowance while divorces report a negative e¤ect on fertility. The model including level as well as di¤erences in the variables has been found to give the best results.Total fertility rate; Economics; Sweden; Time-series

Spatial Dependence and the Determinants of Child Births in Swedish Municipalities 1974-2002

The overall Swedish total fertility rate (TFR) has been shown to fluctuate quite dramatically during the last 40 years, from 2.4 in 1965 reaching down as low as 1.5 in 1999. Although numerous studies in the past have tried to explain this fluctuation, there has been surprisingly little focus on impacts from local or even regional differences. Thus, the purpose of this paper is to analyse, for the first time, whether there exists a significant dispersion in the number of child births normalised by the number of fertile women among Swedish municipalities for the period 1974-2002 and then provide an explanation for occurred differences. Regional differences, as well as the presence of spatial dependence, are first confirmed in an exploratory spatial data analysis. Particularly noticeable is the volatility and how local hotspots emerge and disappear during the study period. Subsequent regression analyses are performed for a selected number of years where we solve for spatial dependence and use economic-, institutional-, sociological-, and geographical characteristics of the municipalities as explanatory variables.

TWO PAPERS ON FERTILITY - THE CASE OF SWEDEN

This thesis consists of two papers dealing with fertility in Sweden. In paper [1] we discuss possible explanations for the variation in the Swedish fertility. We are primarily interested in economic and social conditions and their impact on the total fertility rate between 1965 and 2003. The period is chosen because of (i) the strong fluctuation in the TFR during the period 1965-2003 and (ii) the positive correlation between fertility and the female labour market participation rate from the early 1980s. This contrasts to earlier periods when the negative relationship was prevalent. The results from the study support a positive effect on fertility from female labour market participation and child allowance while divorces report a negative effect. The model structure that includes short run as well as long run effects seems to be the best specified model of a number of different model structures presented in the paper. Contrary to the first paper, the second paper [2] has as starting point the number of children born by women in Sweden. A zero inflated Poisson model is applied to analyse if economic and social conditions have any impact on the number of children born by women in Sweden. The study is based upon women who have completed their life-time fertility cycle. The different variables on completed fertility is compared with women who still are in their fertile ages. The results show a difficulty to combine market work and children. The results also support the assumption that women with higher education have fewer children than women with lower education. However, an important conclusion from the study is that the negative correlation between a woman's level of education and her number of children only hold when incomplete fertility is analysed. The relationship between female education and children is not valid when completed fertility is studied.Total fertility rate; Completed fertility; Non-completed fertility; Time series; Count data; Sweden

Spatial Dependence and the Determinants of Child Births in Swedish Municipalities 1974-2002

The overall Swedish total fertility rate (TFR) has been shown to fluctuate quite dramatically during the last 40 years, from 2.4 in 1965 reaching down as low as 1.5 in 1999. Although numerous studies in the past have tried to explain this fluctuation, there has been surprisingly little focus on impacts from local or even regional differences. Thus, the purpose of this paper is to analyse, for the first time, whether there exists a significant dispersion in the number of child births normalised by the number of fertile women among Swedish municipalities for the period 1974-2002 and then provide an explanation for occurred differences. Regional differences, as well as the presence of spatial dependence, are first confirmed in an exploratory spatial data analysis. Particularly noticeable is the volatility and how local hotspots emerge and disappear during the study period. Subsequent regression analyses are performed for a selected number of years where we solve for spatial dependence and use economic-, institutional-, sociological-, and geographical characteristics of the municipalities as explanatory variables

Coherent control of light interaction with graphene

We report the experimental observation of all-optical modulation of light in a graphene film. The graphene film is scanned across a standing wave formed by two counter-propagating laser beams in a Sagnac interferometer. Through a coherent absorption process the on-axis transmission is modulated with close to 80% efficiency. Furthermore we observe modulation of the scattered energy by mapping the off-axis scattered optical signal: scattering is minimized at a node of the standing wave pattern and maximized at an antinode. The results highlight the possibility to switch and modulate any given optical interaction with deeply sub-wavelength films.Comment: 4 pages, 4 figure

How fast is a twisted photon?

Recent measurements have highlighted that spatially shaped photons travel slower than c, the speed of monochromatic, plane waves in vacuum. Here we investigate the intrinsic delay introduced by `twisting' a photon, i.e. by introducing orbital angular momentum (OAM). In order to do this we use a Hong-Ou-Mandel interferometer to measure the change in delay of single photons when we introduce OAM on a ring-shaped beam that is imaged through a focusing telescope. Our findings show that when all other parameters are held constant the addition of OAM reduces the delay (accelerates) with respect to the same beam with no OAM. We support our results using a theoretical method to calculate the group velocity and gain an intuitive understanding of the measured OAM acceleration by considering a geometrical ray-tracing approach.Comment: 5 pages, 4 figure

Optical analogues of the Newton–Schrödinger equation and boson star evolution

Many gravitational phenomena that lie at the core of our understanding of the Universe have not yet been directly observed. An example in this sense is the boson star that has been proposed as an alternative to some compact objects currently interpreted as being black holes. In the weak field limit, these stars are governed by the Newton–Schrodinger equation. Here we present an optical system that, under appropriate conditions, identically reproduces such equation in two dimensions. A rotating boson star is experimentally and numerically modelled by an optical beam propagating through a medium with a positive thermal nonlinearity and is shown to oscillate in time while also stable up to relatively high densities. For higher densities, instabilities lead to an apparent breakup of the star, yet coherence across the whole structure is maintained. These results show that optical analogues can be used to shed new light on inaccessible gravitational objects

Application of a convolutional neural network to the quality control of MRI defacing

Large-scale neuroimaging datasets present unique challenges for automated processing pipelines. Motivated by a large clinical trials dataset with over 235,000 MRI scans, we consider the challenge of defacing — anonymisation to remove identifying facial features. The defacing process must undergo quality control (QC) checks to ensure that the facial features have been removed and that the brain tissue is left intact. Visual QC checks are time-consuming and can cause delays in preparing data. We have developed a convolutional neural network (CNN) that can assist with the QC of the application of MRI defacing; our CNN is able to distinguish between scans that are correctly defaced and can classify defacing failures into three sub-types to facilitate parameter tuning during remedial re-defacing. Since integrating the CNN into our anonymisation pipeline, over 75,000 scans have been processed. Strict thresholds have been applied so that ambiguous classifications are referred for visual QC checks, however all scans still undergo an efficient verification check before being marked as passed. After applying the thresholds, our network is 92% accurate and can classify nearly half of the scans without the need for protracted manual checks. Our model can generalise across MRI modalities and has comparable performance when tested on an independent dataset. Even with the introduction of the verification checks, incorporation of the CNN has reduced the time spent undertaking QC checks by 42% during initial defacing, and by 35% overall. With the help of the CNN, we have been able to successfully deface 96% of the scans in the project whilst maintaining high QC standards. In a similarly sized new project, we would expect the model to reduce the time spent on manual QC checks by 125 h. Our approach is applicable to other projects with the potential to greatly improve the efficiency of imaging anonymisation pipelines

A Simple Description of Strange Dibaryons in the Skyrme Model

We study strange dibaryons based on the SU(2)-embedded B=2 toroidal soliton. Treating the excursions of the soliton into strange directions as small rigid oscillations, we obtain a good approximation to the bound state approach. We calculate the dibaryon mass formula to order 1/N and find that the doubly strange I=J=0 dibaryon is bound by about 90 MeV.Comment: LaTeX format, 9 pages. No figure

Spectroscopy of 28^{28}Na: shell evolution toward the drip line

Excited states in $^{28}$Na have been studied using the $\beta$-decay of implanted $^{28}$Ne ions at GANIL/LISE as well as the in-beam $\gamma$-ray spectroscopy at the NSCL/S800 facility. New states of positive (J$^{\pi}$=3,4$^+$) and negative (J$^{\pi}$=1-5$^-$) parity are proposed. The former arise from the coupling between 0d$\_{5/2}$ protons and a 0d$\_{3/2}$ neutron, while the latter are due to couplings with 1p$\_{3/2}$ or 0f$\_{7/2}$ neutrons. While the relative energies between the J$^{\pi}$=1-4$^+$ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between $^{26}$F and $^{30}$Al. This points to a possible change in the proton-neutron 0d$\_{5/2}$-0d$\_{3/2}$ effective interaction when moving from stability to the drip line. The presence of J$^{\pi}$=1-4$^-$ negative parity states around 1.5 MeV as well as of a candidate for a J$^{\pi}$=5$^-$ state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f$\_{7/2}$ and 1p$\_{3/2}$ levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the $^{26}$F and $^{25}$O nuclei.Comment: Exp\'erience GANIL/LISE et NSCL/S80