19,863 research outputs found
Tougher Educational Exam Leading to Worse Selection
This paper shows a somehow counterintuitive result: an increase in the exam diculty may reduce the average quality (productivity) of selected individuals. Since the exam does not verify all skills, when its standard rises, candidates with relatively low skills emphasized in the test and high skills demanded in the job may no longer qualify. Hence, an increase in the testing standard may be counterproductive. One implication is that policies should emphasize alignment between the skills tested and those required in the actual jobs.school standard, signaling model, cognitive skill, noncog- nitive skill
SPIDER X - Environmental effects in central and satellite early-type galaxies through the stellar fossil record
A detailed analysis of how environment affects the star formation history of
early-type galaxies (ETGs) is undertaken via high signal to noise ratio stacked
spectra obtained from a sample of 20,977 ETGs (morphologically selected) from
the SDSS-based SPIDER survey. Two major parameters are considered for the
study: the central velocity dispersion (sigma), which relates to local drivers
of star formation, and the mass of the host halo, which relates to
environment-related effects. In addition, we separate the sample between
centrals (the most massive galaxy in a halo) and satellites. We derive trends
of age, metallicity, and [alpha/Fe] enhancement, with sigma. We confirm that
the major driver of stellar population properties in ETGs is velocity
dispersion, with a second-order effect associated to the central/satellite
nature of the galaxy. No environmental dependence is detected for satellite
ETGs, except at low sigma - where satellites in groups or in the outskirts of
clusters tend to be younger than those in the central regions of clusters. In
contrast, the trends for centrals show a significant dependence on halo mass.
Central ETGs in groups (i.e. with a halo mass >10^12.5 M_Sun) have younger
ages, lower [alpha/Fe], and higher internal reddening, than "isolated" systems
(i.e. centrals residing in low-mass, <10^12.5 M_Sun, halos). Our findings imply
that central ETGs in groups formed their stellar component over longer time
scales than "isolated" centrals, mainly because of gas-rich interactions with
their companion galaxies.Comment: 22 pages, 19 figures, accepted for publication in MNRA
The Role of Fermions in Bubble Nucleation
We present a study of the role of fermions in the decay of metastable states
of a scalar field via bubble nucleation. We analyze both one and
three-dimensional systems by using a gradient expansion for the calculation of
the fermionic determinant. The results of the one-dimensional case are compared
to the exact results of previous work.Comment: 15 pages, revtex, 9 figure
Retenção foliar e produtividade da mandioca em Sergipe.
Perda de folhas e a consequente redução na produtividade de raÃzes de mandioca são sintomas comuns da severa deficiência hÃdrica e podridão radicular. Com base nisso, o presente trabalho teve como objetivo determinar as cultivares de mandioca que têm maior retenção foliar e produtividade nas condições edafoclimáticas dos Tabuleiros Costeiros e do Agreste de Sergipe. Com esse fim foram instalados três ensaios, em condição de sequeiro, no delineamento de blocos ao acaso, com 11 cultivares. O número de folhas, a altura total (m), área da copa (m²), teor relativo de clorofila, taxa de assimilação de CO2, massa fresca da parte aérea (t ha-1), comprimento radicular (cm), massa seca radicular (%), produtividade de raÃzes (t·ha-1), teor de amido (%) e produtividade de amido foram as variáveis determinadas. Na condição de déficit hÃdrico severo e prolongado, verificada no verão de 2012, maior número de folhas e área de copa foram determinados nas plantas da cultivar BRS Jarina, e menor número na cultivar Lagoão. O clone 9783-13, que à semelhança das cultivares Lagoão e Irará, teve perda precoce de folhas e de plantas devido à podridão radicular em 2012, no ano agrÃcola 2013-2014, na ausência de podridão, apresentou altaretenção foliar. Esses dados sugerem o impacto da podridão radicular nessas plantas. Por outro lado, em condição de déficit hÃdrico menos severo, no ano agrÃcola 2013-2014, verificou-se, com o inÃcio do perÃodo úmido, aumento na produção de folhas nas plantas da maioria das cultivares, à excessão de BRS Jarina, BRS Tapioqueira, BRS Caipira e Preta do Sul, o que sugere efeito indutor do estresse hÃdrico ameno anterior sobre o crescimento. Conclui-se que as plantas das cultivares BRS Jarina e Irará e o clone 9783-13 destacam-se pela retenção foliar em condições de deficiência hÃdrica prolongada; as plantas da cultivar BRS Kiriris, seguidas pelas plantas de BRS Jarina, são aquelas com maior retenção foliar nas áreas infestadas com podridão radicular; as cultivares BRS Kiriris, Irará, Tianguá, Lagoão, BRS Verdinha, BRS Caipira, BRS Poti branca, BRS Jarina, BRS Tapioqueira, Preta do sul e o clone 9783-13 têm produtividade acima de 40 t·ha-1 nas condições de Umbaúba-SE, na ausência de podridão radicular; as plantas das cultivares BRS Jarina e BRS Caipira destacam-se pela rapidez de recuperação no número de folhas e no teor relativo de clorofila após inÃcio das chuvas e aumento da disponibilidade de umidade no solo.bitstream/item/142456/1/BP93.pd
Actions required to implement integrated care for older people in the community using the World Health Organization's ICOPE approach: A global Delphi consensus study
Background: Integrated care is recognised as an important enabler to healthy ageing, yet few countries have managed to sustainably deliver integrated care for older people. We aimed to gather global consensus on the key actions required to realign health and long-term systems and integrate services to implement the World Health Organization (WHO) Integrated Care for Older People (ICOPE) approach. Methods: A two-round eDelphi study, including a global consultation meeting, was undertaken to identify, refine and generate consensus on the actions required across high-, middle- and lowincome countries to implement the WHO ICOPE approach. In round 1, a framework of 31 actions, empirically derived from previous WHO evidence reviews was presented to panellists to judge the relative importance of each action (numeric rating scale; range:1-9) and provide free-text comments concerning the scope of the actions. These outcomes were discussed and debated at the global consultation meeting. In round 2, a revised framework of 19 actions was presented to panellists to measure their extent of agreement and identify 'essential' actions (five-point Likert scale; range: strongly agree to strongly disagree). A threshold of =80% for agree/strongly agree was set a priori for consensus. Results: After round 1 (n = 80 panellists), median scores across 31 actions ranged from 6 to 9. Based on pre-defined category thresholds for median scores, panellists considered 28 actions (90.3%) as 'important' and three (9.7%) as 'uncertain'. Fifteen additional actions were suggested for inclusion based on free-text comments, creating 46 for consideration at the global consultation meeting. In round 2 (n = 84 panellists), agreement (agree or strongly agree) ranged from 84.6-97.6%, suggesting consensus. Fourteen (73.7%) actions were rated as essential. Conclusion: Fourteen essential actions and five important actions are necessary at system (macro; n = 10) and service (meso; n = 9) levels to implement community-based integrated care for older people
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