Oscillations of retarded differential equations of the neutral and the mixed types

AbstractThis paper is devoted to the study of the oscillation of solutions of delay differential equations of the neutral and mixed types. Some general results are proved for certain general Volterra type neutral differential equations and many particular cases are discussed

Electricity Prices and Energy Efficiency - A Regression Discontinuity Approach

This study analyzes the relationship between electricity prices and energy efficiency in German companies. Economic theory suggests that higher energy prices will lead to higher energy efficiency. This paper tests this hypothesis empirically by analyzing company-level data from Germany. In particular, a special provision of the German Renewable Energy Act (REA) is exploited. According to this provision, some companies are exempted from paying the “REA markup” - a markup charged on the electricity price in order to finance subsidies for renewable energy. Exempted companies pay lower electricity prices and can therefore be used as a counterfactual in a regression discontinuity analysis. The results of the analysis suggest that energy prices have a statistically significant and positive effect on energy efficiency

Flatness of the setting Sun

Atmospheric refraction is responsible for the bending of light-rays in the atmosphere. It is a result of the continuous decrease in the refractive index of the air as a function of altitude. A well-known consequence of this phenomenon is the apparently elliptic shape of the setting or rising Sun (or full-Moon). In the present paper we systematically investigate this phenomenon in a standard atmosphere. Theoretical and numerical calculations are compared with experimental data. The asymmetric rim of the Sun is computed as a function of its inclination angle, observational height and meteorological conditions characterized by pressure, temperature and lapse-rate. We reveal and illustrate some extreme and highly unusual situations.Comment: RevTex, 10 pages, 14 Figures. A web-page is accompanying this study: http://www.fi.uib.no/~neda/sunset/index.htm

The weight of patriarchy? Gender obesity gaps in the Middle East and North Africa (MENA)

The worldwide obesity epidemic has impacted women more heavily than men. These gender-based differences are particularly pronounced in the Middle East and North Africa (MENA) region where gender obesity gaps on average exceed 10 percentage points. This paper examines one of the explanations, namely the role of female empowerment on gender gaps in obesity. We study the effect of several measures of female empowerment including female labor market participation on gender obesity gaps over a time span of 41 years (1975-2016) in a sample of 190 countries. We document that after controlling for a number relevant controls, gender obesity gaps are only associated to measures of female empowerment in the MENA region but that this is not true worldwide. We then use an instrumental variable approach in order to illustrate that the causality runs indeed from empowerment, proxy it by both labor market and political participation to gender obesity gaps and not vice versa. Our results reveal that a one percentage point increase in female labor market participation (female MPs in national parliament) predicts a 0.2 (0.09) percentage point decrease in gender gaps in obesity in the MENA regio

Average number of flips in pancake sorting

We are given a stack of pancakes of different sizes and the only allowed operation is to take several pancakes from top and flip them. The unburnt version requires the pancakes to be sorted by their sizes at the end, while in the burnt version they additionally need to be oriented burnt-side down. We present an algorithm with the average number of flips, needed to sort a stack of n burnt pancakes, equal to 7n/4+O(1) and a randomized algorithm for the unburnt version with at most 17n/12+O(1) flips on average. In addition, we show that in the burnt version, the average number of flips of any algorithm is at least n+\Omega(n/log n) and conjecture that some algorithm can reach n+\Theta(n/log n). We also slightly increase the lower bound on g(n), the minimum number of flips needed to sort the worst stack of n burnt pancakes. This bound, together with the upper bound found by Heydari and Sudborough in 1997, gives the exact number of flips to sort the previously conjectured worst stack -I_n for n=3 mod 4 and n>=15. Finally we present exact values of f(n) up to n=19 and of g(n) up to n=17 and disprove a conjecture of Cohen and Blum by showing that the burnt stack -I_{15} is not the worst one for n=15.Comment: 21 pages, new computational results for unburnt pancakes (up to n=19

On approximation of the solutions of delay differential equations by using piecewise constant arguments

By using the Gronwall Bellman inequality we prove some limit relations between the solutions of delay differential equations with continuous arguments and the solutions of some related delay differential equations with piecewise constant arguments(EPCA). EPCA are strongly related to some discrete difference equations arising in numerical analysis, therefore the results can be used to compute numerical solutions of delay differential equations. We also consider the delay differential equations of neutral type by applying a generalization of the Gronwall Bellman inequality

Public policy and social determinants of nutrition behaviour and outcomes – quasi-experimental evidence from low- and middle-income countries

As of today approximately 3.19 billion people worldwide, i.e. 42 percent of the world’s population, are malnourished. Out of them 811 million are undernourished and 2.38 billion people are overweight or obese. Both undernutrition and overnutrition are a health risk for the affected individuals, and lower their productive capacities and labour market perspectives. This thesis provides evidence on how public policy can create an incentive architecture which is conducive to healthy nutrition behaviour in low and middle income countries (LMICs). The first paper analyses whether the conditional cash transfer programme Bolsa Familia in Brazil has influenced food consumption and nutritional outcomes among its beneficiaries. The results show that the bulk of the cash transfers is spent on food, with a disproportionate increase in the consumption of dairy and sugary products, but no overall impact on overweight and obesity. The second paper investigates whether the free health insurance programme Seguro Popular in Mexico has altered nutritional choices and outcomes among lowincome families in Mexico. The analysis suggests that the programme has increased obesity among those who were already overweight at baseline, and that beneficiaries have reduced the consumption of carbohydrates in favour of meat. The third paper focuses on the importance of gender norms in determining nutritional outcomes and describes the growing disparities in obesity rates between women and men. It shows that female empowerment leads to lower gender obesity gaps in a worldwide sample of countries, but that this effect is entirely driven by the MENA region. The fourth paper focuses on peer effects and social learning. It assesses the impact of a behaviour change campaign to reduce child malnutrition in Mozambique. The paper shows that the programme did not only improve nutritional practices among the programme’s participants, but also among untreated neighbours, suggesting the presence of social learning effects