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.

Semantic annotation in ubiquitous healthcare skills-based learning environments

This paper describes initial work on developing a semantic annotation system for the augmentation of skills-based learning for Healthcare. Scenario driven skills-based learning takes place in an augmented hospital ward simulation involving a patient simulator known as SimMan. The semantic annotation software enables real-time annotations of these simulations for debriefing of the students, student self study and better analysis of the learning approaches of mentors. A description of the developed system is provided with initial findings and future directions for the work.<br/

How reliable are Hanle measurements in metals in a three-terminal geometry?

We test the validity of Hanle measurements in three-terminal devices by using aluminum (Al) and gold (Au). The obtained Hanle and inverted Hanle-like curves show an anomalous behavior. First, we measure Hanle signals 8 orders of magnitude larger than those predicted by standard theory. Second, the temperature and voltage dependences of the signal do not match with the tunneling spin polarization of the ferromagnetic contact. Finally, the spin relaxation times obtained with this method are independent of the choice of the metallic channel. These results are not compatible with spin accumulation in the metal. Furthermore, a scaling of the Hanle signal with the interface resistance of the devices suggests that the measured signal is originated in the tunnel junction.Comment: 9 pages, 5 figure

Molecular characterization of a phytoplasma causing phyllody in clover and other herbaceous hosts in northern Italy

Red clover (Trifolium pratense) and Ladino clover (Trifolium repens) plants showing phytoplasma-associated symptoms (yellowing/reddening, virescence and phyllody) have been recovered in Friuli-Venezia Giulia, Italy. Using AluI RFLP analysis of PCR amplified 16S rDNA we showed that the disease can be caused independently by two phylogenetically distinct phytoplasmas. One of them showed the very typical 16S rDNA RFLP pattern of the agent of Clover Phyllody in Canada (CCPh). The 16S rDNA of the other phytoplasma (Italian Clover Phyllody phytoplasma, ICPhp) has been PCR amplified, cloned and sequenced. The sequence revealed high similarity (>98%) with phytoplasmas belonging to the X disease cluster, which includes organisms not reported to cause phyllody on their hosts. The analysis by AluI RFLP of the PCR amplified pathogen 16S rDNA from other herbaceous plants (Crepis biennis, Taraxacum officinale, Leucanthemum vulgare) collected nearby with phytoplasma-associated symptoms showed similar patterns. Southern blot hybridization of their EcoRI digested total DNA revealed identical RFLP patterns, suggesting that the causative agent may be the same organism

Room-temperature air-stable spin transport in bathocuproine-based spin valves

Organic semiconductors, characterized by weak spin-scattering mechanisms, are attractive materials for those spintronic applications in which the spin information needs to be retained for long times. Prototypical spin-valve devices employing organic interlayers sandwiched between ferromagnetic materials possess a figure of merit (magnetoresistance (MR)) comparable to their fully inorganic counterparts. However, these results are a matter of debate as the conductivity of the devices does not show the expected temperature dependence. Here we show spin valves with an interlayer of bathocuproine in which the transport takes place unambiguously through the organic layer and where the electron spin coherence is maintained over large distances (>60 nm) at room temperature. Additionally, the devices show excellent air stability, with MR values almost unaltered after 70 days of storage under ambient conditions, making bathocuproine an interesting material for future spintronic applications.Fil: Sun, Xiangnan. CIC nanoGUNE; EspañaFil: Gobbi, Marco. Université de Strasbourg; Francia. CIC nanoGUNE; EspañaFil: Bedoya Pinto, Amilcar. CIC nanoGUNE; EspañaFil: Txoperena, Oihana. CIC nanoGUNE; EspañaFil: Golmar, Federico. CIC nanoGUNE; España. Instituto Nacional de Tecnología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Llopis, Roger. CIC nanoGUNE; EspañaFil: Chuvilin, Andrey. CIC nanoGUNE; España. Fundación Vasca para la Ciencia; EspañaFil: Casanova, Félix. CIC nanoGUNE; España. Fundación Vasca para la Ciencia; EspañaFil: Hueso, Luis E.. CIC nanoGUNE; España. Fundación Vasca para la Ciencia; Españ

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

Three-dimensional apoptotic nuclear behavior analyzed by means of field emission in lens scanning electron microscope

Apoptosis is an essential biological function required during embryogenesis, tissue homeostasis, organ development and immune system regulation. It is an active cell death pathway involved in a variety of pathological conditions. During this process cytoskeletal proteins appear damaged and undergo an enzymatic disassembling, leading to formation of apoptotic features. This study was designed to examine the threedimensional chromatin behavior and cytoskeleton involvement, in particular actin re-modeling. HL-60 cells, exposed to hyperthermia, a known apoptotic trigger, were examined by means of a Field Emission in Lens Scanning Electron Microscope (FEISEM). Ultrastructural observations revealed in treated cells the presence of apoptotic patterns after hyperthermia trigger. In particular, three-dimensional apoptotic chromatin rearrangements appeared involving the translocation of filamentous actin from cytoplasm to the nucleus. FEISEM immunogold techniques showed actin labeling and its precise three-dimensional localization in the diffuse chromatin, well separated from the condensed one. The actin presence in dispersed chromatin inside the apoptotic nucleus can be considered an important feature, indispensable to permit the apoptotic machinery evolution

Optimization of Esterase Production in Solid-State Fermentation of Agricultural Digestate

The continuous increase in biogas production poses the need for innovative applications for its by-products. Solid-state fermentation (SSF) has regained attention in the development of several products because of the possibility to use low-cost and easily available substrates, such as organic wastes. SSF represents a valuable process for agricultural digestate valorization in terms of enzyme production. In the present study, cellulase and esterase were produced by Trichoderma asperellum R on a digestate-based substrate in SSF, with esterase as the highest obtained activity. After assessing the effect of light on it, the esterase production in SSF was optimized using response surface methodology. The influence of substrate composition, temperature and humidity on the enzyme production was evaluated on two sets of data generated based on digestate concentration (50% and 70% w/w). The statistical analyses revealed that these parameters affected esterase production only when Trichoderma asperellum grew on substrate containing 50% w/w of digestate. The best esterase activity (264.6 mU/mg total protein) was achieved with the following optimized SSF parameters: 50% digestate, 50% fruits, 10% sawdust, 30 & DEG;C. The current finding of esterase production on digestate-based substrates makes the SSF method presented here a sustainable and completely circular technology