A Model of Voluntary Childlessness

Demographers and sociologists have studied and asked for a theory of childlessness for more than two decades, however, this specific choice of zero fertility has not interested economists. Nowadays, facts show us that permanent childlessness can concern up to 30% of all women of a cohort. This paper gives an endogenous fertility model that looks in detail to the mechanisms leading to fluctuations in childlessness. Two mechanisms are considered. The first mechanism goes through the inter-generational evolution of preferences, that can be either exogenous or endogenous. I show that under some values of the parameters, oscillatory dynamics of childlessness may arise. The second mechanism goes through the female labor market; a more gender parity labor environment and an increase in the fixed cost of becoming parents could be an explanation for the dynamics of fertility and childlessness that we have observed in the United States since the early nineteenth century.

Childlessness is high in the US once again, but this time it’s driven by choice, not poverty.

Recent years have seen a rise in childlessness rates in the US close to levels not seen for more than a century. In new research which examines the drivers of childlessness then and now, Thomas Baudin, David de la Croix and Paula E. Gobbi find that while in the early 20th century poverty meant that many women were forced into having fewer children, better education and higher income for women are now the causes of childlessness

COMPORTAMIENTO DEL INTERVALO QT CORREGIDO EN ARTRITIS TEMPRANA

Introducción: La  dispersión del  intervalo QT  ha sido descripta en  pacientes con artritis reumatoidea (AR) y  puede ser un marcador útil de morbi-mortalidad cardiovascular.Objetivos: Conocer el comportamiento del intervalo QT corregido (iQTc) en pacientes con AT y evaluar la asociación con  actividad de la enfermedad (AE).Material y Métodos:  Se realizó un estudio comparativo de corte transversal que incluyó pacientes mayores de 16 años, con diagnóstico de artritis temprana (AT) , atendidos en la  Unidad de Reumatología del Hospital Córdoba, desde enero de 2010 a diciembre de 2013. El grupo control se apareó por edad, sexo y antecedentes patológicos.  Los criterios de exclusión fueron evidencias  de IAM,  arritmia, potasemia&gt;5mEq/L,  ingesta de fármacos que afecten el QT. Se recolectaron datos demográficos, la actividad de la enfermedad se midió por DiseaseActivity Score (DAS 28), clasificando la actividad de la enfermedad en Baja AE, DAS 28 menor a 3,2,  Moderada/ Alta mayor de 3.2;   y se realizó ECG con técnica  estándar. El  intervalo QT fue medido desde el comienzo del complejo QRS hasta el final de la onda T. Para obtener el valor del iQTc, se utilizó la fórmula de Bazett.Resultados: El número de pacientes fue de 31, 83.9 % de sexo femenino y con edad media de 41.9 años, el DAS 28 promedio de 5.09. El grupo control incluyo 31 individuos con  una edad media de 42.2. El intervalo QT fue de 0.376 mm/s y el iQTc de 0.408 en AT y el QT fue de 0.381 mm/s y el iQTc de 0.415mm/s en el grupo control (p NS, p NS). El QT y el iQTc fueron de 0.39 y 0.38mm/s en los pacientes con baja  AE; 0.37mm/s y 0.411en Moderada / Alta AE (p=NS).Conclusión: El iQTc no demostró alteraciones ni se relacionó con actividad de la enfermedad en  AT   Background: The QT interval modification has been described in patients with Rheumatoid Arthritis (RA) and it could be a useful marker of cardiovascular morbidity and mortality.Aims: To evaluate the QT interval modifications in patients with early arthritis (EA) and its association with disease activity (DA).METHODS: We studied patients with diagnosis of EA attended to Rheumatology Unit at Córdoba Hospital from January 2010 to December 2013. Control group was population age, gender and cardiovascular risk factors matched. Exclusion criteria were: myocardial infarction, arrhythmia, K level &gt;5, or anti-arrhythmia treatment. ECG was performed by standard technique and QT interval was measured from the beginning of QRS to the end of T wave. QTC value was calculated by Bazzet formula.  The activity disease was measured by Disease Activity Score (DAS 28), and was considered low disease activity below 3.2, and moderate / high disease activity more than 3,2.RESULTS: 31 patients were included with 83.9 % of females and the mean age was  41.9 years old and DAS 28 was 5.09.  31 persons were included as a control group with a mean age of 42.2 years old.  QT interval was  0.376 mm/s  and l QTC  0.408  in EA and  QT was  0.381 mm/s and  QTC  0.415 mm/s  in the control group ( p= NS, p= NS).  QT interval and  QTC were  0.39 and 0.38 in low DA patients; 0.37 and  0.411 in Moderate / High DA ( p=NS)CONCLUSIONS: The QT interval  was not modified and it was not related with DA in EA. </p

Equatorial Ionosphere Bottom-type Spread-F Observed by OI 630.0 nm Airglow Imaging

Bottom‐type spread F events were observed in the south American equatorial region by a VHF coherent radar and an ionosonde at São Luís (2.5°S, 44.3°W), an ionosonde at Fortaleza (3.9°S, 38.4° W) and an airglow OI 630.0 nm imager at Cariri (7.4°S, 36.5°W) and Brasilia (14.8°S, 47.6°W). In the evening of September 30, 2005, a long duration (∼70 minutes) bottom side scattering layer, confined in a narrow height region, was observed. At the same time all‐sky imager observed sinusoidal intensity depletions in the zonal plane extending more than 1500 km and elongated along the magnetic meridian. No strong spread F structures developed during the period. Subsequently well developed plasma bubbles were observed. This suggests that the observed bottom‐type spread F is an initial phase of the plasma bubbles. We report, for the first time, longitudinal and latitudinal extension of the bottom‐type spread F as diagnosed by optical imagers. Citation: Takahashi, H., et al. (2010), Equatorial ionosphere bottom‐type spread F observed by OI 630.0 nm airglow imaging

Simultaneous Observation of Ionospheric Plasma Bubbles and Mesospheric Gravity Waves During the SpreadFEx Campaign

During the Spread F Experiment campaign, under NASA Living with a Star (LWS) program, carried out in the South American Magnetic Equator region from 22 September to 8 November 2005, two airglow CCD imagers, located at Cariri (7.4° S, 36.5° W, geomag. 11° S) and near Brasilia (14.8° S, 47.6° W, geomag. 10° S) were operated simultaneously and measured the equatorial ionospheric bubbles and their time evolution by monitoring the airglow OI 6300 intensity depletions. Simultaneous observation of the mesospheric OH wave structures made it possible to investigate the relationship between the bubble formation in the ionosphere and the gravity wave activity at around 90 km. On the evening of 30 September 2005, comb-like OI 6300 depletions with a distance of ~130 km between the adjacent ones were observed. During the same period, a mesospheric gravity wave with a horizontal wavelength of ~130 km was observed. From the 17 nights of observation during the campaign period, there was a good correlation between the OI 6300 depletion distances and the gravity wave horizontal wavelengths in the mesosphere with a statistically significant level, suggesting a direct contribution of the mesospheric gravity wave to plasma bubble seeding in the equatorial ionosphere

Overview and Summary of the Spread F Experiment (SpreadFex)

We provide here an overview of, and a summary of results arising from, an extensive experimental campaign (the Spread F Experiment, or SpreadFEx) performed from September to November 2005, with primary measurements in Brazil. The motivation was to define the potential role of neutral atmosphere dynamics, specifically gravity wave motions propagating upward from the lower atmosphere, in seeding Rayleigh-Taylor instability (RTI) and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12, and the GUVI instrument aboard the TIMED satellite

The spread-F Experiment (SpreadFEx): Program overview and first results

We performed an extensive experimental campaign (the spread F Experiment, or SpreadFEx) from September to November 2005 to attempt to define the role of neutral atmosphere dynamics, specifically wave motions propagating upward from the lower atmosphere, in seeding equatorial spread F and plasma bubbles extending to higher altitudes. Campaign measurements focused on the Brazilian sector and included ground-based optical, radar, digisonde, and GPS measurements at a number of fixed and temporary sites. Related data on convection and plasma bubble structures were also collected by GOES 12 and the GUVI instrument aboard the TIMED satellite. Initial results of our analyses of SpreadFEx and related data indicate 1) extensive gravity wave (GW) activity apparently linked to deep convection predominantly to the west of our measurement sites, 2) the presence of small-scale GWactivity confined to lower altitudes, 3) larger-scaleGWactivity apparently penetrating to much higher altitudes suggested by electron density and TEC fluctuations in the E and F regions, 4) substantial GW amplitudes implied by digisonde electron densities, and 5) apparent direct links of these perturbations in the lower F region to spread F and plasma bubbles extending to much higher altitudes. Related efforts with correlative data are defining 6) the occurrence and locations of deep convection, 7) the spatial and temporal evolutions of plasma bubbles, the 8) 2D (height-resolved) structures of plasma bubbles, and 9) the expected propagation of GWs and tides from the lower atmosphere into the thermosphere and ionosphere