The Role of Prices, Income, and Preferences

In the U.S., lower income households have a less healthy consumption basket than higher income ones. This paper studies the drivers of such nutrition inequality. I use longitudinal home-scanner data to estimate a demand system on food products, and measure the contribution of prices, disposable income and preferences to nutrition inequality. Disposable income and preferences have a predominant and quantitatively similar role in explaining consumption basket differences across income groups. Instead, prices have a limited effect. Further, I merge nutritional label information to assess, through a series of counterfactual exercises, the effect of income subsidies on nutrition quality. For example, I show that increasing the budget of a low-income household to the average level of the higher income households (a 45% increase in food expenditures) leads to an increase in protein consumption of approximately 5% and a decrease in sugar consumption of approximately 10%

Rumen function and digestion parameters associated with differences between sheep in methane emissions when fed chaffed lucerne hay

An indoor experiment involving 10 rumen-cannulated Romney sheep was conducted in May and June 1998 at AgResearch Grasslands, Palmerston North, New Zealand, under restricted feeding conditions. in order to test the hypothesis that animal factors, in particular rumen fractional outflow rate (FOR) and rumen volume, have an influence on the between-sheep variation in methane (CH4) emission. Sheep were fed 2-hourly on chaffed lucerne hay. Following an acclimatization period of 21 days, the experiment lasted 16 days. Energy and nitrogen (N) balances were measured on days 1-6. Cr-EDTA marker was continuously infused into the rumen from day 9 to 16, and rumen contents emptied and sampled on days 13 and 16. Particulate and fluid FOR were estimated using feed lignin and Cr-EDTA, respectively. Daily CH, production was measured by the sulphur hexafluoride tracer technique on days 2, 5, 6, 12 and 15 of the experiment. CH4 production (g/day) was positively correlated with the pool size of organic matter (OM) in the rumen (OM pool, g) (r = 0.84, P = 0.002), OM intake (OMI, g/day) (r = 0.67, P = 0.04), and the rumen fill (g. wet digesta) (r = 0.76, P = 0.01). Multiple regression analysis showed that CH4 production was best predicted (R-2 = 0.88) as a function of OM pool and the molar % of butyrate; however, OM pool alone accounted for a large proportion (R-2 = 0.71) of the variation in CH4 production. CH4 yield (% gross energy intake, % GEI) was negatively correlated with the particulate FOR (%/h) ( r= -0.75, P = 0.01) and buffering capacity of rumen fluid (mmol HCl) (r = -0.72, P = 0.02) but positively correlated with the digestibility of cellulose (r = 0.66, P = 0.04). Multiple regression analysis showed that CH, yield was best predicted as a function of particulate FOR, OMI (g/kg liveweight(0.75)) and the molar % of butyrate (R-2 = 0.88). Particulate FOR alone explained a large proportion (R-2 = 0.57) of the variation in CH4 Yield. Particulate FOR was negatively correlated with rumen fill (r = -0.69, P = 0.03) and digestibility of cellulose (r = -0.65, P = 0.04). These results suggest that sheep with lower rumen particulate FOR (i.e. longer rumen retention times) had larger rumen fills and higher fibre digestibilities and CH4 yields. If rumen particulate FOR is to be used as a tool for CH4 mitigation, the repeatability of its relationship to CH4 emission must be assessed, preferably under grazing conditions

Persistence of differences between sheep in methane emission under generous grazing conditions

Four low and four high methane (CH4) emitters were selected from a flock of 20 Romney sheep on the basis of CH4 production rates per unit of intake, measured at grazing using the sulphur hexafluoride (SF,) tracer technique. Methane emissions from these sheep were monitored at grazing for four periods (P): October, November, January and February 1999/2000. All measurements were carried out on perennial ryegrass/white clover pasture under generous herbage allowance, and the sheep were maintained on similar pastures during non-measurement periods. The tracer technique was used for all the CH4 measurements and feed DM intake was calculated from total faecal collection and estimated DM digestibility. Data for liveweight (LW), gross energy intake (GEI) and CH4 emission were analysed using split-plot analysis of variance. In addition, a between-period rank order correlation analysis was carried out for CH4 emission data. Low CH4 emitters were heavier (P < 0.05) than the high emitters in all the periods, but they did not differ (P < 0.05) in their gross energy intakes (GEL MJ/kg LW0.75). Low and high CH4 emitters consistently maintained their initial rankings in CH4 yield (% GEI) throughout the subsequent periods and the correlation analysis of rank order for CH4 yield showed strong between-period correlation coefficients, although this was weaker in the last period. It is suggested that feeding conditions that maximize feed intake (e.g. generous allowance of good quality pasture under grazing) favour the expression and persistence of between-sheep differences in CH4 yield

The Effect of Affirmative Action on Workers’ Outcomes

Fifty-six years after the introduction of affirmative action in employment in the U.S., there is a lack of consensus regarding the effect of this policy on workers’ careers (Holzer and Neumark, 2000). This paper contributes to fill this gap by building and analyzing a dataset that allows us to quantify the effects of affirmative action in employment on workers’ labor market outcomes. This paper circumvents prior data restrictions by constructing the first administrative database containing worker-level information (from the Longitudinal Employment Household Dynamics) as well as the federal contractor status of workers’ employers (from the Equal Employment Opportunity Commission Data and Federal Procurement Data). We estimate the causal effects of affirmative action on workers’ outcomes exploiting different features specified by the legal obligations of the regulation in a regression discontinuity setting

Equilibrium Wage-Setting and the Life-Cycle Gender Pay Gap

We study the drivers of the life-cycle gender wage gap. In our equilibrium search model, firms set the unit price of human capital of men and women, value stable matches with high productivity gains and can statistically discriminate across genders based on differences in turnover and human capital processes. This endogenous wage setting is crucial for evaluating policies targeting the gap. We estimate the model on the first 15 years of workers’ careers in the NLSY79 data, and find that differences in workers’ and firms’ productivities explain 27% and 28% of the life-cycle gap respectively, while statistical discrimination explains 45%

Mercury and selenium binding biomolecules in terrestrial mammals (Cervus elaphus and Sus scrofa) from a mercury exposed area

Acknowledgements The authors are grateful to Junta de Comunidades de Castilla-La Mancha (PCC-05-004-2, PAI06-0094, PCI-08-0096, PEII09-0032-5329) and the Ministerio de Economía y Competitividad (CTQ2013-48411-P) for financial support. M.J. Patiño Ropero acknowledges the Junta de Comunidades de Castilla-La Mancha for her PhD. fellowship.Peer reviewedPostprin

Methane emission by alpaca and sheep fed on lucerne hay or grazed on pastures of perennial ryegrass/white clover or birdsfoot trefoil

Based on the knowledge that alpaca (Lama pacos) have a lower fractional outflow rate of feed particles (particulate FOR) from their forestomach than sheep (San Martin 1987), the current study measured methane (CH4) production and other digestion parameters in these species in three successive experiments (1, 2 and 3): Experiment 1, lucerne hay fed indoors; Experiment 2, grazed on perennial ryegrass/white clover pasture (PRG/WC); and Experiment 3, grazed on birdsfoot trefoil (Lotus corniculatits) pasture (Lotus). Six male alpaca and six castrated Romney sheep were simultaneously and successively fed on the forages either ad libitium or at generous herbage allowances (grazing). CH4 production (g/day) (using the sulphur hexafluoride tracer technique), voluntary feed intake (VFI), diet quality, and protozoa counts and volatile fatty acid concentrations in samples of forestomach contents were determined. In addition, feed digestibility, energy and nitrogen (N) balances and microbial N supply from the forestomach (using purine derivatives excretion) were measured in Experiment 1. Diets selected by alpaca were of lower quality than those selected by sheep, and the voluntary gross energy intakes (GEI, MJ) per kg of liveweight(0.75) were consistently lower (P0.05) in their CH4 yields (% GEI) when fed on lucerne hay (5.1 v. 4.7), but alpaca had a higher CH4 yield when fed on PRG/WC (9.4 v. 7.5, P0.05) in diet N partition or microbial N yield, but alpaca had higher (P<0.05) neutral detergent fibre digestibility (0.478 v. 0.461) and lower (P<0.01) urinary energy losses (5.2 v. 5.8 % GEI) than sheep. It is suggested that differences between these species in forestomach particulate FOR might have been the underlying physiological mechanism responsible for the differences in CH4 yield, although the between-species differences in VFI and diet quality also had a major effect on it

The Unequal Effects of Covid-19 on Economists' Research Productivity

The current lock-down measures are expected to disproportionately reduce women's labor productivity in the short run. This paper analyzes the effects of these measures on economists' research productivity. We explore the patterns of working papers publications using data from the NBER Working Papers Series, the CEPR Discussion Paper Series, the newly established research repository Covid Economics: Vetted and Real Time Papers and VoxEU columns. Our analysis suggests that although the relative number of female authors in non-pandemic related research has remained stable with respect to recent years (at around 20%), women constitute only 12% of total number of authors working on COVID-19 research. Moreover, we see that it is primarily senior economists who are contributing to this new area. Mid-career and junior economists record the biggest gap between non-COVID and COVID research, and the gender di erences are particularly stark at the mid-career level. Mid-career female economists have not yet started working on this new research area: only 12 mid-career female authors have contributed to COVID-19 related research so far, out of a total of 647 distinct authors in our dataset of papers (NBER, CEPR and CEPR Covid Economics)