7,735 research outputs found

    Human capital, culture and the onset of the demographic transition

    Get PDF
    This paper uses estimates of the dates at which different countries have experienced their demographic transitions to examine the main historical determinants of these transitions. We first show that genetic distance to the United Kingdom, a measure of cultural relatedness used in Spolaore and Wacziarg (2009), is positively associated with the onset of the demographic transition, implying that countries that have a larger genetic distance from the UK tend to experience later transitions. We then unveil a plausible mechanism that can rationalize this result. We show that genetic distance to the UK is negatively related to a country's initial human capital, measured as its schooling level in 1870. One interpretation of this finding is that a larger genetic distance is associated with higher barriers to technological diffusion and hence a lower demand for human capital. This low demand for human capital then delays the demographic transition by providing less incentives for households to switch from quantity to quality of children. Instrumenting initial human capital using genetic distance to the UK and alternative measures of adherence to Protestantism, we confirm the causal link between human capital and the onset of the demographic transition. Further, we show that the impact of cultural relatedness to the UK can be mainly attributed to its effect on educational levels

    Analytical computation of the off-axis Effective Area of grazing incidence X-ray mirrors

    Full text link
    Focusing mirrors for X-ray telescopes in grazing incidence, introduced in the 70s, are characterized in terms of their performance by their imaging quality and effective area, which in turn determines their sensitivity. Even though the on-axis effective area is assumed in general to characterize the collecting power of an X-ray optic, the telescope capability of imaging extended X-ray sources is also determined by the variation in its effective area with the off-axis angle. [...] The complex task of designing optics for future X-ray telescopes entails detailed computations of both imaging quality and effective area on- and off-axis. Because of their apparent complexity, both aspects have been, so far, treated by using ray-tracing routines aimed at simulating the interaction of X-ray photons with the reflecting surfaces of a given focusing system. Although this approach has been widely exploited and proven to be effective, it would also be attractive to regard the same problem from an analytical viewpoint, to assess an optical design of an X-ray optical module with a simpler calculation than a ray-tracing routine. [...] We have developed useful analytical formulae for the off-axis effective area of a double-reflection mirror in the double cone approximation, requiring only an integration and the standard routines to calculate the X-ray coating reflectivity for a given incidence angle. [...] Algebraic expressions are provided for the mirror geometric area, as a function of the off-axis angle. Finally, the results of the analytical computations presented here are validated by comparison with the corresponding predictions of a ray-tracing code.Comment: 12 pages, 11 figures, accepted for publication in "Astronomy & Astrophysics", section "Instruments, observational techniques, and data processing". Updated version after grammatical revision and typos correctio

    Current medical treatment of estrogen receptor-positive breast cancer

    Get PDF
    Approximately 80% of breast cancers (BC) are estrogen receptor (ER)-positive and thus endocrine therapy (ET) should be considered complementary to surgery in the majority of patients. The advantages of oophorectomy, adrenalectomy and hypophysectomy in women with advanced BC have been demonstrated many years ago, and currently ET consist of (i) ovarian function suppression (OFS), usually obtained using gonadotropin-releasing hormone agonists (GnRHa), (ii) selective estrogen receptor modulators or down-regulators (SERMs or SERDs), (iii) aromatase inhibitors (AIs), or a combination of two or more drugs. For patients aged less than 50 years and ER+ BC, there is no conclusive evidence that the combination of OFS and SERMs (i.e. tamoxifen) or chemotherapy is superior to OFS alone. Tamoxifen users exhibit a reduced risk of BC, both invasive and in situ, especially during the first 5 years of therapy, and extending the treatment to 10 years further reduced the risk of recurrences. SERDs (i.e. fulvestrant) are especially useful in the neoadjuvant treatment of advanced BC, alone or in combination with either cytotoxic agents or AIs. There are two types of AIs: type I are permanent steroidal inhibitors of aromatase, while type II are reversible nonsteroidal inhibitors. Several studies demonstrated the superiority of the third-generation AIs (i.e. anastrozole and letrozole) compared with tamoxifen, and adjuvant therapy with AIs reduces the recurrence risk especially in patients with advanced BC. Unfortunately, some cancers are or became ET-resistant, and thus other drugs have been suggested in combination with SERMs or AIs, including cyclin-dependent kinase 4/6 inhibitors (palbociclib) and mammalian target of rapamycin (mTOR) inhibitors, such as everolimus. Further studies are required to confirm their real usefulness

    Scattering of Giant Holes

    Full text link
    We study scalar excitations of high spin operators in N=4 super Yang-Mills theory, which are dual to solitons propagating on a long folded string in AdS_3 x S^1. In the spin chain description of the gauge theory, these are associated to holes in the magnon distribution in the sl(2,R) sector. We compute the all-loop hole S-matrix from the asymptotic Bethe ansatz, and expand in leading orders at weak and strong coupling. The worldsheet S-matrix of solitonic excitations on the GKP string is calculated using semiclassical quantization. We find an exact agreement between the gauge theory and string theory results.Comment: 13 pages. v2: minor corrections, references adde

    A comparison of efficient permutation tests for unbalanced ANOVA in two by two designs--and their behavior under heteroscedasticity

    Full text link
    We compare different permutation tests and some parametric counterparts that are applicable to unbalanced designs in two by two designs. First the different approaches are shortly summarized. Then we investigate the behavior of the tests in a simulation study. A special focus is on the behavior of the tests under heteroscedastic variances.Comment: 20 pages, 9 figures, Working Paper of the Department of Management And Enigineering of the University of Padov

    Longitudinal spin Seebeck coefficient: heat flux vs. temperature difference method

    Get PDF
    The determination of the longitudinal spin Seebeck effect (LSSE) coefficient is currently plagued by a large uncertainty due to the poor reproducibility of the experimental conditions used in its measurement. In this work we present a detailed analysis of two different methods used for the determination of the LSSE coefficient. We have performed LSSE experiments in different laboratories, by using different setups and employing both the temperature difference method and the heat flux method. We found that the lack of reproducibility can be mainly attributed to the thermal contact resistance between the sample and the thermal baths which generate the temperature gradient. Due to the variation of the thermal resistance, we found that the scaling of the LSSE voltage to the heat flux through the sample rather than to the temperature difference across the sample greatly reduces the uncertainty. The characteristics of a single YIG/Pt LSSE device obtained with two different setups was (1.143±0.007)107(1.143\pm0.007)\cdot 10^{-7} Vm/W and (1.101±0.015)107(1.101\pm0.015)\cdot 10^{-7} Vm/W with the heat flux method and (2.313±0.017)107(2.313\pm0.017)\cdot 10^{-7} V/K and (4.956±0.005)107(4.956\pm0.005)\cdot 10^{-7} V/K with the temperature difference method. This shows that systematic errors can be considerably reduced with the heat flux method.Comment: PDFLaTeX, 10 pages, 6 figure

    Holocene palaeoceanographic evolution of the Iskenderun bay, South-Eastern Turkey, as a response to river mouth diversions and human impact

    Get PDF
    A quantitative study of benthic foraminifera, sediment texture and composition from two cores was performed to unravel the environmental evolution of the Iskenderun Bay (eastern Turkey) in the Holocene. Core 29 (NE Iskenderun Bay) consists of clay and silt from the top of the core down to 35 cm with dominant bioclasts (coral Cladocora caespitosa) from 35 cm down to the bottom of the core. Core 92, located near an ancient Ceyhan River mouth (Yumurtalik), consists of sandy and silty sediment passing to homogeneous clay and silt at about 48 cm from the top. Several grab samples show very coarse biogenic detritus covered by a centimetric veneer of sandy silt and clay. Radiocarbon dating of corals, molluscs and algae from core 29 and five selected grab samples, the sediment and foraminiferal study indicate that at least three pulses of muddy sedimentation occurred in the bay. (1) An older pulse (about 3700 yrs BP) related to the large-scale forest clearing (Beysheir Occupation Phase). (2) Another pulse coincides with a major delta progradation of the Ceyhan River at about 2140 years BP. (3) A younger pulse follows the diversion of the Ceyhan River mouth toward Yumurtalik, from the Middle Age to 1935.Species interpreted as tolerant of low salinity indicate that the influence of the Ceyhan was minor when the river drained directly into the Mediterranean Sea (approximately 2000 years BP) and progressively increased when the river diverted towards Yumurtalik

    TBA-like equations and Casimir effect in (non-)perturbative AdS/CFT

    Full text link
    We consider high spin, ss, long twist, LL, planar operators (asymptotic Bethe Ansatz) of strong N=4{\cal N}=4 SYM. Precisely, we compute the minimal anomalous dimensions for large 't Hooft coupling λ\lambda to the lowest order of the (string) scaling variable L/(lnSλ)\ell \sim L/ (\ln \mathcal{S} \sqrt{\lambda}) with GKP string size lnS2ln(s/λ)\sim\ln \mathcal{S}\equiv 2 \ln (s/\sqrt{\lambda}). At the leading order (lnS)2(\ln \mathcal{S}) \cdot \ell ^2 , we can confirm the O(6) non-linear sigma model description for this bulk term, without boundary term (lnS)0(\ln \mathcal{S})^0. Going further, we derive, extending the O(6) regime, the exact effect of the size finiteness. In particular, we compute, at all loops, the first Casimir correction 0/lnS\ell ^0/\ln \mathcal{S} (in terms of the infinite size O(6) NLSM), which reveals only one massless mode (out of five), as predictable once the O(6) description has been extended. Consequently, upon comparing with string theory expansion, at one loop our findings agree for large twist, while reveal for negligible twist, already at this order, the appearance of wrapping. At two loops, as well as for next loops and orders, we can produce predictions, which may guide future string computations.Comment: Version 2 with: new exact expression for the Casimir energy derived (beyond the first two loops of the previous version); UV theory formulated and analysed extensively in the Appendix C; origin of the O(6) NLSM scattering clarified; typos correct and references adde

    Survival probabilities of loggerhead sea turtles (<i>Caretta caretta</i>) estimated from capture-mark-recapture data in the Mediterranean Sea

    Get PDF
    Las probabilidades de supervivencia de la tortuga boba (Caretta caretta) se han estimado por primera vez en el Mediterráneo analizando datos de 3254 marcajes y 134 recapturas en esta región. La mayoría de las tortugas eran juveniles encontrados en el mar. Las recapturas fueron reavistamientos de individuos vivos y recuperaciones de individuos muertos. Los datos se analizaron mediante el modelo de Baker, versión modificada del de Cormack-Jolly-Seber que puede combinar recaptura, reavistamientos de individuos vivos e individuos recuperados muertos. Se obtuvo una probabilidad de supervivencia anual de 0.73 (IC 95% = 0.67-0.78; n=3254), y debe considerarse como una estima conservativa debido a una desconocida, aunque no insignificante, tasa de perdida de marcados. Este estudio ofrece una estima preliminar de las probabilidades de supervivencia de los estadios de desarrollo "en el mar" para la población mediterránea amenazada de tortuga boba marina, y proporciona las primeras observaciones sobre la magnitud de la sospechada mortalidad inducida por el hombre en la región. El modelo, utilizado aquí por primera vez en tortugas marinas podría ser utilizado para obtener estimas de supervivencia a partir de otros datos con pocas o sin recapturas reales, pero con otros tipos de datos de recaptura frecuentemente producidos por programas de marcado de estos animales de amplia distribución
    corecore