Interpreting the evidence on life cycle skill formation

This paper presents economic models of child development that capture the essence of recent findings from the empirical literature on skill formation. The goal of this essay is to provide a theoretical framework for interpreting the evidence from a vast empirical literature, for guiding the next generation of empirical studies, and for formulating policy. Central to our analysis is the concept that childhood has more than one stage. We formalize the concepts of self-productivity and complementarity of human capital investments and use them to explain the evidence on skill formation. Together, they explain why skill begets skill through a multiplier process. Skill formation is a life cycle process. It starts in the womb and goes on throughout life. Families play a role in this process that is far more important than the role of schools. There are multiple skills and multiple abilities that are important for adult success. Abilities are both inherited and created, and the traditional debate about nature versus nurture is scientiÞcally obsolete. Human capital investment exhibits both self-productivity and complementarity. Skill attainment at one stage of the life cycle raises skill attainment at later stages of the life cycle (self-productivity). Early investment facilitates the productivity of later investment (complementarity). Early investments are not productive if they are not followed up by later investments (another aspect of complementarity). This complementarity explains why there is no equity-efficiency trade-off for early investment. The returns to investing early in the life cycle are high. Remediation of inadequate early investments is difficult and very costly as a consequence of both self-productivity and complementarity

Accessing the Acceleration of the Universe with Sunyaev-Zel'dovich and X-ray Data from Galaxy Clusters

By using exclusively the Sunyaev-Zel'dovich effect and X-ray surface brightness data from 25 galaxy clusters in the redshift range 0.023< z < 0.784 we access cosmic acceleration employing a kinematic description. Such result is fully independent on the validity of any metric gravity theory, the possible matter-energy contents filling the Universe, as well as on the SNe Ia Hubble diagram.Comment: 3 pages, 4 figures, To appear in the Proceedings of the Twelfth Marcel Grossmann Meeting on General Relativit

Are Galaxy Clusters Suggesting an Accelerating Universe?

The present cosmic accelerating stage is discussed through a new kinematic method based on the Sunyaev- Zel'dovich effect (SZE) and X-ray surface brightness data from galaxy clusters. By using the SZE/X-ray data from 38 galaxy clusters in the redshift range $0.14 \leq z \leq 0.89$ [Bonamente et al., Astrop. J. {\bf 647}, 25 (2006)] it is found that the present Universe is accelerating and that the transition from an earlier decelerating to a late time accelerating regime is relatively recent. The ability of the ongoing Planck satellite mission to obtain tighter constraints on the expansion history through SZE/X-ray angular diameters is also discussed. Our results are fully independent on the validity of any metric gravity theory, the possible matter- energy contents filling the Universe, as well as on the SNe Ia Hubble diagram from which the presenting accelerating stage was inferred.Comment: 6 pages, 6 figures, AIP Conf. Proc. Invisible Universe: Proceedings of the Conferenc

Solar type II radio bursts associated with CME expansions as shown by EUV waves

We investigate the physical conditions of the sources of two metric Type-II bursts associated with CME expansions with the aim of verifying the relationship between the shocks and the CMEs, comparing the heights of the radio sources and the heights of the EUV waves associated with the CMEs. The heights of the EUV waves associated with the events were determined in relation to the wave fronts. The heights of the shocks were estimated by applying two different density models to the frequencies of the Type-II emissions and compared with the heights of the EUV waves. For the 13 June 2010 event, with band-splitting, the shock speed was estimated from the frequency drifts of the upper and lower branches of the harmonic lane, taking into account the H/F frequency ratio fH/fF = 2. Exponential fits on the intensity maxima of the branches revealed to be more consistent with the morphology of the spectrum of this event. For the 6 June 2012 event, with no band-splitting and with a clear fundamental lane on the spectrum, the shock speed was estimated directly from the frequency drift of the fundamental emission, determined by linear fit on the intensity maxima of the lane. For each event, the most appropriate density model was adopted to estimate the physical parameters of the radio source. The 13 June 2010 event presented a shock speed of 664-719 km/s, consistent with the average speed of the EUV wave fronts of 609 km/s. The 6 June 2012 event was related to a shock of speed of 211-461 km/s, also consistent with the average speed of the EUV wave fronts of 418 km/s. For both events, the heights of the EUV wave revealed to be compatible with the heights of the radio source, assuming a radial propagation of the shock.Comment: Accepted for publication in Astronomy and Astrophysic

Concentração de carboidratos e umidade em raízes de mandioca açucarada (Manihot esculenta Crantz) Pará.

Objetivou-se quantificar as concentrações dos açucares: glicose, frutose e sacarose, o teor de amido e a umidade de genótipos de mandioca açucarada mantidos no Banco Ativo de Germoplasma (BAG) da Embrapa Amazônia Oriental. A concentração de glicose variou de 0,94% no genótipo 9 a 2,02 % no genótipo 05; a concentração de frutose variou de 0,70% no genótipo 02 a 1,53 % no genótipo 03; e para sacarose a variação foi de 0,15% nos genótipos 01 e 14 a 1,31% no genótipo 05. Portanto, o açúcar em maior concentração foi a glicose, seguido da frutose e sacarose, com médias de 1,33%, 0,88% a 0,51%, respectivamente. O genótipo 05 apresentou as maiores concentrações de glicose, frutose e sacarose. O teor de amido variou de 4,36% a 9,53% nos genótipos 15 e 7, respectivamente, apresentando média geral de 5,78 %. Os valores de umidade foram elevados com variação de 77,25% a 93,70% nos genótipos 13 e 14, respectivamente, sendo a média de 89,46%. Assim, no geral, a quantidade de açucares disponível para serem fermentados é em torno de 5% e, portando sendo o possível de serem obtidos rendimentos razoáveis quando comparada a outras espécies que são utilizadas para obtenção de etanol

THE TOUCH-DOWN AND TAKE-OFF ANGLES IN DIFFERENT PHASES OF 100 M SPRINT RUN

The variation in running velocity over a 100 m dash has been studied extensively in the last decade. Very few studies, however, have dealt with the changes in technique occurring between the second acceleration (from the normal sprinting position of run the maximal velocity until is reached), maximal velocity and deceleration phases. The purpose of this study was to quantify the touch-down (TO) and take-off (TO) angles in a 100 m sprint run, before, during and after the maximal velocity phase. Ten sprinters were filmed during these phases using a high-speed video camera operating at 250 Hz in a 100 m dash. The results of this study suggest that the Trunk Angle at TO influenced the TO angle. Furthermore, the horizontal distance between the centre of gravity and the Foot at TO, is an important technical characteristic influencing the stride length and the stride rate which provoke the running velocity variation