On the Weights of Nations: Assigning Voting Weights in a Heterogenous Union

Consider a voting procedure where countries, states, or districts comprising a union each elect representatives who then participate in later votes at the union level on their behalf. The countries, provinces, and states may vary in their populations and composition. If we wish to maximize the total expected utility of all agents in the union, how to weight the votes of the representatives of the different countries, states or districts at the union level? We provide a simple characterization of the efficient voting rule in terms of the weights assigned to different districts and the voting threshold (how large a qualified majority is needed to induce change versus the status quo). Next, in the context of a model of the correlation structure of agents preferences, we analyze how voting weights relate to the population size of a country. We then analyze the voting weights in Council of the European Union under the Nice Treaty and the recently proposed constitution, and contrast them under different versions of our model.

Choosing How to Choose: Self-Stable Majority Rules and Constitutions

Constitutional arrangements affect the decisions made by a society. We study how this effect leads to preferences of citizens over constitutions; and ultimately how this has a feedback that determines which constitutions can survive in a given society. Constitutions are stylized here, to consist of a voting rule for ordinary business and possibly different voting rule for making changes to the constitution. We deffine an equilibrium notion for constitutions, called self-stability, whereby under the rules of a self-stable constitution, the society would not vote to change the constitution. We argue that only self-stable constitutions will endure. We prove that self-stable constitutions always exist, but that most constitutions (even very prominent ones) may not be self-stable for some societies. We show that constitutions where the voting rule used to amend the constitution is the same as the voting rule used for ordinary business are dangerously simplistic, and there are (many) societies for which no such constitution is self-stable rule. We conclude with a characterization of the set of self-stable constitutions that use majority rule for ordinary business.

Self-Selection Consistent Functions

This paper studies collective choice rules whose outcomes consist of a collection of simultaneous decisions, each one of which is the only concern of some group of individuals in society. The need for such rules arises in different contexts, including the establishment of jurisdictions, the location of multiple public facilities, or the election of representative committees. We define a notion of allocation consistency requiring that each partial aspect of the global decision taken by society as a whole should be ratified by the group of agents who are directly concerned with this particular aspect. We investigate the possibility of designing envy-free allocation consistent rules, we also explore whether such rules may also respect the Condorcet criterion.Consistency, Condorcet criterion

Stable Condorcet Rules

We consider the following allocation problem: A fixed number of public facilities must be located on a line. Society is composed of $N$ agents, who must be allocated to one and only one of these facilities. Agents have single peaked preferences over the possible location of the facilities they are assigned to, and do not care about the location of the rest of facilities. There is no congestion. In this context, we observe that if a public decision is a Condorcet winner, then it satisfies nice properties of internal and external stability. Though in many contexts and for some preference profiles there may be no Condorcet winners, we study the extent to which stability can be made compatible with the requirement of choosing Condorcet winners whenever they exist.Social Choice Correspondences, Condorcet Rules, Stability, Simpson Rule

Experimental balance to estimate efficiency in the use of nitrogen in rabbit breeding

[EN] Defining the composition and properties of manure in livestock production is critical in order to minimise possible environmental impacts stemming from its management. In this study, a nitrogen balance was carried out during two identical fattening periods (Experiments 1 and 2) in growing rabbits from weaning (age 28 d and live weight about 0.6 kg) to slaughter (age 61 d and live weight about 1.8 kg). The breeding conditions were typical for Spanish rabbit production. The objectives were to quantify the total nitrogen excreted by the animals and to estimate the average efficiency in the use of this nutrient, in comparison to other species. Animal weight, feed intake, and the production of faeces and urine were monitored weekly in a set of eight cages with nine rabbits in each, performing weekly analyses for nitrogen content in feed, urine and faeces. The overall nitrogen excretion was 50.2 g N per animal in Experiment 1 and 46.9 g N per animal in Experiment 2, which corresponded to about 58% of the total nitrogen intake. Urine and faeces contributed to overall nitrogen excretion in approximately the same proportions. The nitrogen excretion ratio was 40 grams per kilogram of animal produced. According to this ratio, rabbit breeding is less efficient in the use of nitrogen than raising broilers, but more than fattening pigs.The authors thank the Spanish Ministry of Education and Science for the economic support to conduct this study (Project GASFARM AGL2005-07297).Calvet Sanz, S.; Estellés Barber, F.; Hermida, B.; Blumetto, O.; Torres Salvador, AG. (2008). Experimental balance to estimate efficiency in the use of nitrogen in rabbit breeding. World Rabbit Science. 16(4). https://doi.org/10.4995/wrs.2008.615SWORD16

Characterization of the indoor environment and gas emissions in rabbit farms

[EN] There is a need to characterize gas concentrations and emissions from rabbit production. A study was conducted in order to determine ammonia, nitrous oxide and carbon dioxide concentrations and emissions in three rabbit farms in the Spanish Mediterranean area. Gas emissions were measured for 187 days in two different production stages (reproductive does and fattening rabbits). Gas concentrations were measured every two hours. Indoor temperature, relative humidity and ventilation flow were measured hourly. As a result, indoor temperature and relative humidity varied throughout the year, following a sinusoidal daily variation pattern. Maximum gas concentrations (14.3 mg/m3 of NH3, 7041 mg/m3 of CO2 and 5.10 mg/m3 of N2O) did not exceed the maximum recommended thresholds considering human health and animal welfare. Ammonia emissions were on average 55.9 and 10.2 mg/h per reproductive doe and fattening rabbit, respectively, and they were affected by temperature and relative humidity. The average carbon dioxide emission was 12588 mg/h per animal for does and 3341 mg/h for fattening rabbits. Nitrous oxide emission from does was 10.3 mg/h per animal, whereas for fattening rabbits the emission was negligible. Daily variation patterns of all measured parameters were observed and characterised in this study.The authors thank the Spanish Ministry of Science and Innovation (Project GasFarm AGL2008-04125) for the economic support to conduct this study. Acquisition of the gas analyser was co-financed by the Generalitat Valenciana (Conselleria de Empresa, Universidad y Ciencia) and FEDER funds.Calvet Sanz, S.; Cambra López, M.; Estellés Barber, F. (2011). Characterization of the indoor environment and gas emissions in rabbit farms. World Rabbit Science. 19(1). https://doi.org/10.4995/wrs.2011.802SWORD19

Voting by Committees under Constraints

We consider social choice problems where a society must choose a subset from a set of objects. Specifically, we characterize the families of strategy-proof voting procedures when not all possible subsets of objects are feasible, and voters' preferences are separable or additively representable.Voting, Strategy-proofness, Additive and Separable Preferences.

Uncertainty Modelling to Evaluate Nitrogen Balances As a Tool to Determine N2 and N2O Formation in Ammonia Bioscrubbers

Biological scrubbers aim at reducing gaseous ammonia emissions by transferring it to a water phase followed by conversion to nitrite and nitrate. A small part of the removed nitrogen may be emitted as N 2 and N 2O produced as a result of denitrification processes. Due to the large greenhouse warming potential of N 2O, even a small emission could be a point of concern. Determining these N losses in form of N 2 and N 2O via nitrogen balance is an alternative, but little is known about the uncertainty associated to this method. The main aim of this work was to develop an uncertainty model that evaluated N-balances in biological scrubbers in terms of result uncertainty. Secondary objectives were to provide a methodology to determine individual uncertainties involved, and to conduct a sensitivity analysis to identify the main contributors to the final uncertainty. For a defined scenario (biotrickling scrubber, 70% NH 3 removal; 5% of inlet N-NH 3 lost as N 2 and N 2O), the standard uncertainty expressed in relative terms of the average was 132% (released N in form of N 2 and N 2O). Main contributors to the final uncertainty were airflow rate and water volume in the scrubber basin. Uncertainty of the measurements of gaseous NH 3 concentrations and N compounds in water had a reduced effect on the final uncertainty. Based on these results, N balances are not recommended to evaluate N 2 and N 2O formation in biological scrubbers, at least for the conditions considered in this work. © Copyright 2012, Mary Ann Liebert, Inc.The auhors would like to thank the Netherlands Ministry of Economic Affairs, Agriculture and Innovation, and the Netherlands Ministry of Infrastructure and the Environment, for financial support.Estellés Barber, F.; Calvet Sanz, S.; Melse, RW.; Ogink, N. (2012). Uncertainty Modelling to Evaluate Nitrogen Balances As a Tool to Determine N2 and N2O Formation in Ammonia Bioscrubbers. Environmental Engineering Science. 29(6):1-6. doi:10.1089/ees.2011.01891629