Improving water productivity in agriculture in developing economies: in search of new avenues

Water ProductivityCrop productionWheatCottonEvapotranspirationEcnomic aspects

Neutrix Calculus and Finite Quantum Field Theory

In general, quantum field theories (QFT) require regularizations and infinite renormalizations due to ultraviolet divergences in their loop calculations. Furthermore, perturbation series in theories like QED are not convergent series, but are asymptotic series. We apply neutrix calculus, developed in connection with asymptotic series and divergent integrals, to QFT,obtaining finite renormalizations. While none of the physically measurable results in renormalizable QFT is changed, quantum gravity is rendered more manageable in the neutrix framework.Comment: 10 pages; LaTeX; version to appear in J. Phys. A: Math. Gen. as a Letter to the Edito

Otimização dos parâmetros hidráulicos do solo por meio de modelagem inversa utilizando o programa "PEST".

As informações dos parâmetros hidráulicos de solo constituem em dados importantes em estudos com modelagem do fluxo de água, transporte de solutos ou contaminantes bem como em simulação de crescimento vegetal. O objetivo desse estudo foi otimizar os parâmetros hidráulicos do solo pelo método de modelagem inversa. Os solos pertencem a duas áreas experimentais conduzidos em área comercial de cana-de-açúcar. O programa PEST (Parameter ESTimation) foi utilizado com o intuito de minimizar a soma dos quadrados dos resíduos entre o conteúdo de água no solo medido nos dois experimentos pelo método gravimétrico, com o conteúdo de água no solo simulada pelo modelo SWAP/WOFOST. A variação do índice estatístico RMSE entre o conteúdo de água no solo medida em campo com o simulado pelo modelo foi semelhante em ambos os locais e em média apresentou valor de 0,0281 e 0,0274 m3 m-3. O método de modelagem inversa realizado pelo programa PEST mostrou ser eficaz na otimização dos parâmetros hidráulicos do solo em ambos os locais de estudo

Bigravity and Lorentz-violating Massive Gravity

Bigravity is a natural arena where a non-linear theory of massive gravity can be formulated. If the interaction between the metrics $f$ and $g$ is non-derivative, spherically symmetric exact solutions can be found. At large distances from the origin, these are generically Lorentz-breaking bi-flat solutions (provided that the corresponding vacuum energies are adjusted appropriately). The spectrum of linearized perturbations around such backgrounds contains a massless as well as a massive graviton, with {\em two} physical polarizations each. There are no propagating vectors or scalars, and the theory is ghost free (as happens with certain massive gravities with explicit breaking of Lorentz invariance). At the linearized level, corrections to GR are proportional to the square of the graviton mass, and so there is no vDVZ discontinuity. Surprisingly, the solution of linear theory for a static spherically symmetric source does {\em not} agree with the linearization of any of the known exact solutions. The latter coincide with the standard Schwarzschild-(A)dS solutions of General Relativity, with no corrections at all. Another interesting class of solutions is obtained where $f$ and $g$ are proportional to each other. The case of bi-de Sitter solutions is analyzed in some detail.Comment: 25 pages. v3 Typos corrected, references added. v4 Introduction extende

The quality of student dialogue in citizenship education

This study investigates the relationship between the quality of student dialogue and students’ ability to justify their viewpoints on a moral issue. A curriculum unit for dialogic citizenship education was developed and implemented in the 8th grade of secondary education. In the final lesson, students discussed a moral issue and then wrote an essay on it. The results show that students who made more value-related utterances during the discussion also referred more often and more explicitly in their individually written essays to moral values. This study indicates that the quality of the content of students’ dialogue is important for their ability to substantiate their opinion on moral issues with value-laden argumentation. Approaches to citizenship education in which dialogue is a central element should, therefore, pay specific attention to the validation of ideas in student dialogue

Is bastaardering tussen zomer- en wintereik een gevaar voor de vitaliteit van eiken

Over het begrip soort bij zomereik en wintereik (twee soorten of één soot met twee ecotypen), de morfologische verschillen, het voorkomen van soorten met intermediaire morfologische kenmerken in gemengde eikenbossen, en de vraag of hierbij sprake is van echte hybriden of niet. Kruisingsexperimenten en internationaal onderzoek naar de genetische diversiteit met behulp van bladkenmerken lossen het probleem van de bastaardisering tussen zomer- en wintereiken in Europa niet op; ouderschapsanalyse met behulp van DNA-technologie moet uitkomst brenge

Self-reported domain-specific and accelerometer-based physical activity and sedentary behaviour in relation to psychological distress among an urban Asian population

Background: The interpretation of previous studies on the association of physical activity and sedentary behaviour with psychological health is limited by the use of mostly self-reported physical activity and sedentary behaviour, and a focus on Western populations. We aimed to explore the association of self-reported and devise-based measures of physical activity and sedentary behaviour domains on psychological distress in an urban multi-ethnic Asian population. Methods: From a population-based cross-sectional study of adults aged 18-79 years, data were used from an overall sample (n = 2653) with complete self-reported total physical activity/sedentary behaviour and domain-specific physical activity data, and a subsample (n = 703) with self-reported domain-specific sedentary behaviour and accelerometry data. Physical activity and sedentary behaviour data were collected using the Global Physical Activity Questionnaire (GPAQ), a domain-specific sedentary behaviour questionnaire and accelerometers. The Kessler Screening Scale (K6) and General Health Questionnaire (GHQ-12) were used to assess psychological distress. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals, adjusted for socio-demographic and lifestyle characteristics. Results: The sample comprised 45.0% men (median age = 45.0 years). The prevalence of psychological distress based on the K6 and GHQ-12 was 8.4% and 21.7%, respectively. In the adjusted model, higher levels of self-reported moderate-to-vigorous physical activity (MVPA) were associated with significantly higher odds for K6 (OR = 1.47 [1.03-2.10]; p-trend = 0.03) but not GHQ-12 (OR = 0.97 [0.77-1.23]; p-trend = 0.79), when comparing the highest with the lowest tertile. Accelerometry-assessed MVPA was not significantly associated with K6 (p-trend = 0.50) nor GHQ-12 (p-trend = 0.74). The highest tertile of leisure-time physical activity, but not work- or transport-domain activity, was associated with less psychological distress using K6 (OR = 0.65 [0.43-0.97]; p-trend = 0.02) and GHQ-12 (OR = 0.72 [0.55-0.93]; p-trend = 0.01). Self-reported sedentary behaviour was not associated with K6 (p-trend = 0.90) and GHQ-12 (p-trend = 0.33). The highest tertile of accelerometry-assessed sedentary behaviour was associated with significantly higher odds for K6 (OR = 1.93 [1.00-3.75]; p-trend = 0.04), but not GHQ-12 (OR = 1.34 [0.86-2.08]; p-trend = 0.18). Conclusions: Higher levels of leisure-time physical activity and lower levels of accelerometer-based sedentary behaviour were associated with lower psychological distress. This study underscores the importance of assessing accelerometer-based and domain-specific activity in relation to mental health, instead of solely focusing on total volume of activity