The optimum quantity of money: Theory and evidence

In this paper we propose a simple and general model for computing the Ramsey optimal inflation tax, which includes several models from the previous literature as special cases. We show that it cannot be claimed that the Friedman rule is always optimal (or always non--optimal) on theoretical grounds. The Friedman rule is optimal or not, depending on conditions related to the shape of various relevant functions. One contribution of this paper is to relate these conditions to {\it measurable} variables such as the interest rate or the consumption elasticity of money demand. We find that it tends to be optimal to tax money when there are economies of scale in the demand for money (the scale elasticity is smaller than one) and/or when money is required for the payment of consumption or wage taxes. We find that it tends to be optimal to tax money more heavily when the interest elasticity of money demand is small. We present empirical evidence on the parameters that determine the optimal inflation tax. Calibrating the model to a variety of empirical studies yields a optimal nominal interest rate of less than 1\%/year, although that finding is sensitive to the calibration.

Cross-country data on the quantity of schooling: a selective survey and some quality measures

We survey a number of papers that have focused on the construction of cross-country data sets on average years of schooling. We discuss the construction of the different series, compare their profiles and construct indicators of their information content. The discussion focuses on a sample of OECD countries but we also provide some results for a large non-OECD sample.

Optimal regulation of specialized medical care in a mixed system

We study the optimal public intervention in setting minimum standards of formation for specialized medical care. The abilities the physicians obtain by means of their training allow them to improve their performance as providers of cure and earn some monopoly rents.. Our aim is to characterize the most efficient regulation in this field taking into account different regulatory frameworks. We find that the existing situation in some countries, in which the amount of specialization is controlled, and the costs of this process of specialization are publicly financed, can be supported as the best possible intervention.

Increasing the scalability and the speedup of a fish school distributed simulator

El present treball fa un anàlisi i desenvolupament sobre les millores en la velocitat i en l’escalabilitat d'un simulador distribuït de grups de peixos. Aquests resultats s’han obtingut fent servir una nova estratègia de comunicació per als processos lògics (LPs) i canvis en l'algoritme de selecció de veïns que s'aplica a cadascun dels peixos en cada pas de simulació. L’idea proposada permet que cada procés lògic anticipi futures necessitats de dades pels seus veïns reduint el temps de comunicació al limitar la quantitat de missatges intercanviats entre els LPs. El nou algoritme de selecció dels veïns es va desenvolupar amb l'objectiu d'evitar treball innecessari permetent la disminució de les instruccions executades en cada pas de simulació i per cadascun del peixos simulats reduint de forma significativa el temps de simulació.

Occurrence and bioaccumulation study of PCDD and PCDF from mineral feed additives

Occurrence of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was evaluated in sepiolite as a widely employed binder and anti-caking agent for animal feed. Also, naturally contaminated kaolinitic clay was used for comparative purposes. Since sepiolite shows remarkable adsorption properties, particular interest was paid to the extraction steps as they become critical for the final determination of these pollutants in such matrixes. Furthermore, classical Soxhlet extraction using different extracting strategies as well as acid treatment were carried out with simultaneous liquid-liquid extraction. Results obtained depended on the extraction procedure applied. Acid treatment or Soxhlet extraction using a mixture of toluene:ethanol as solvent allowed to reach the minimum requirements of recovery rates. However, Soxhlet extraction using a mixture cyclohexane:toluene as extracting solvent did not allow to comply with minimum specifications for recovery. Significant differences were obtained in TEQ units when acid treatment was applied in comparison to Soxhlet extraction. This fact can be explained because the use of drastic acid conditions allows removing strongly adsorbed analytes which can be uniquely extracted after a total destruction of the crystalline structure of sepiolite. On the contrary, Soxhlet extraction was not able to destroy the structure of sepiolite and as a consequence the PCDDs/Fs were strongly adsorbed in the internal structure of the mineral. From biological point of view the availability of these toxicants constitutes a critical aspect playing an important role in the final decision choosing particular analytical procedures. Then, acid conditions in the digestive tract should be taken into account. In this scenario, a bioaccumulation study was conducted to evaluate the transference of PCDDs/PCDFs from the sepiolite into the animal tissues when fed with feed containing sepiolite. To this end, chickens were used as a model to examine the bioavailability of PCDDs/PCDFs. Four groups of chickens were exposed through their diet to a control feed, feed with 3% w/w sepiolite as additive, feed contaminated with PCDDs/PCDFs at concentration around 2.8 pg WHO-TEQ/g and feed with 2% of a contaminated kaolinitic clay (460 pg TEQ/g mineral). Livers of the four studied groups were analyzed throughout the exposure period. Results of this trial showed that the performance of broilers was not affected by the presence of dioxins at levels tested, and chickens did not show any abnormal behaviour. Dioxins intentionally added to the diet were absorbed and accumulated in the liver in a significant manner, whereas the PCDDs/Fs from sepiolite were not available for chickens since livers from broilers fed 3% sepiolite presented similar WHO-TEQ values than those from broilers fed control diet.

Evaluation of subsidies programs to sell green cars: Impact on prices, quantities and efficiency

During the recent period of economic crisis, many countries have introduced scrappage schemes to boost the sale and production of vehicles, particularly of vehicles designed to pollute less. In this paper, we analyze the impact of a particular scheme in Spain (Plan2000E) on vehicle prices and sales figures as well as on the reduction of polluting emissions from vehicles on the road. We considered the introduction of this scheme an exogenous policy change and because we could distinguish a control group (non-subsidized vehicles) and a treatment group (subsidized vehicles), before and after the introduction of the Plan, we were able to carry out our analysis as a quasi-natural experiment. Our study reveals that manufacturers increased vehicle prices by the same amount they were granted through the Plan (1,000 €). In terms of sales, econometric estimations revealed an increase of almost 5% as a result of the implementation of the Plan. With regard to environmental efficiency, we compared the costs (inverted quantity of money) and the benefits of the program (reductions in polluting emissions and additional fiscal revenues) and found that the Plan would only be beneficial if it boosted demand by at least 30%.

On optimal computation of MPLS label binding for multipoint-to-point connections

Most network operators have considered reducing Label Switched Routers (LSR) label spaces (i.e. the number of labels that can be used) as a means of simplifying management of underlaying Virtual Private Networks (VPNs) and, hence, reducing operational expenditure (OPEX). This letter discusses the problem of reducing the label spaces in Multiprotocol Label Switched (MPLS) networks using label merging - better known as MultiPoint-to-Point (MP2P) connections. Because of its origins in IP, MP2P connections have been considered to have tree- shapes with Label Switched Paths (LSP) as branches. Due to this fact, previous works by many authors affirm that the problem of minimizing the label space using MP2P in MPLS - the Merging Problem - cannot be solved optimally with a polynomial algorithm (NP-complete), since it involves a hard- decision problem. However, in this letter, the Merging Problem is analyzed, from the perspective of MPLS, and it is deduced that tree-shapes in MP2P connections are irrelevant. By overriding this tree-shape consideration, it is possible to perform label merging in polynomial time. Based on how MPLS signaling works, this letter proposes an algorithm to compute the minimum number of labels using label merging: the Full Label Merging algorithm. As conclusion, we reclassify the Merging Problem as Polynomial-solvable, instead of NP-complete. In addition, simulation experiments confirm that without the tree-branch selection problem, more labels can be reduced

A search theory of money and commerce with Neoclassical production

This paper advances a highly tractable model with search theoretic foundations for money and neoclassical growth. In the model, manufacturingand commerce are distinct and separate activities. In manufacturing,goods are efficiently produced combining capital and labor. In commerce,goods are exchanged in bilateral meetings. The model is applied to studythe effects of inßation on capital accumulation and welfare. With realisticparameters, inflation has large negative effects on welfare even though itraises capital and output. In contrast, with cash-in-advance, a deviceinformally motivated with bilateral trading, inflation depresses capitaland output and has a negligible effect on welfare.

On the concept of optimality interval

The approximants to regular continued fractions constitute `best approximations' to the numbers they converge to in two ways known as of the first and the second kind.This property of continued fractions provides a solution to Gosper's problem of the batting average: if the batting average of a baseball player is 0.334, what is the minimum number of times he has been at bat? In this paper, we tackle somehow the inverse question: given a rational number P/Q, what is the set of all numbers for which P/Q is a `best approximation' of one or the other kind? We prove that inboth cases these `Optimality Sets' are intervals and we give aprecise description of their endpoints.

Study and modeling of the desintegration kinetics of coated paper

The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%lsv and from the dissipated energy per volume unit (Ss). The %slv is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 revise rotor speed and for different fiber consistency (6, 8, 10, 12 and 14%). The results showed that the values of experimental disintegration kinetic constant, Ko, through the analysis of Somerville index, as function of time. Increased, the disintegration time was drastically reduced. The calculation of the disintegration kinetic constant (modelled Ko), extracted from the Rayleigh’s dissipation function, showed a good correlation with the experimental values using the evolution of the Somerville index or with the dissipated energy

Study and modeling of the desintegration kinetics of coated paper

The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%lsv and from the dissipated energy per volume unit (Ss). The %slv is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 revise rotor speed and for different fiber consistency (6, 8, 10, 12 and 14%). The results showed that the values of experimental disintegration kinetic constant, Ko, through the analysis of Somerville index, as function of time. Increased, the disintegration time was drastically reduced. The calculation of the disintegration kinetic constant (modelled Ko), extracted from the Rayleigh’s dissipation function, showed a good correlation with the experimental values using the evolution of the Somerville index or with the dissipated energy

The minimum tree for a given zero-entropy period

We answer the following question: given any n∈ℕ, which is the minimum number of endpoints en of a tree admitting a zero-entropy map f with a periodic orbit of period n? We prove that en=s1s2…sk−∑i=2ksisi+1…sk, where n=s1s2…sk is the decomposition of n into a product of primes such that si≤si+1 for 1≤iof period m with em>e, then the topological entropy of f is positive

Effects of nutrients and turbulence on the production of transparent exopolymer particles: a mesocosm study

The production of transparent exopolymer particles (TEP) in response to several environmental variables was studied in 2 mesocosm experiments. The first (Expt 1) examined a gradient of 4 nutrient levels; the second (Expt 2) examined different conditions of silicate availability and zooplankton presence. Tanks were separated in 2 series, one subjected to turbulence and the other not influenced by turbulence. In tanks with nutrient addition, TEP were rapidly formed, with net apparent production rates closely linked to chl a growth rates, suggesting that phytoplankton cells were actively exuding TEP precursors. High nutrient availability increased the absolute concentration of TEP; however, the relative quantity of TEP produced was found to be lower, as TEP concentration per unit of phytoplankton biomass was inversely related to the initial nitrate dose. In Expt 1, an increase in TEP volume (3 to 48 µm equivalent spherical diameter) with nutrient dose was observed; in Expt 2, both silicate addition and turbulence enhanced TEP production and favored aggregation to larger TEP (>48 µm). The presence of zooplankton lowered TEP concentration and changed the size distribution of TEP, presumably by grazing on TEP or phytoplankton. For lower nutrient concentrations, the ratio of particulate organic carbon (POC) to particulate organic nitrogen (PON) followed the Redfield ratio. At higher nutrient conditions, when nutrients were exhausted during the post-bloom, a decoupling of carbon and nitrogen dynamics occurred and was correlated to TEP formation, with a large flow of carbon channeled toward the TEP pool in turbulent tanks. TEP accounted for an increase in POC concentration of 50% in high-nutrient and turbulent conditions. The study of TEP dynamics is crucial to understanding the biogeochemical response of the aquatic system to forcing variables such as nutrient availability and turbulence intensity.

Study and modeling of the desintegration kinetics of coated paper

The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%lsv and from the dissipated energy per volume unit (Ss). The %slv is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 revise rotor speed and for different fiber consistency (6, 8, 10, 12 and 14%). The results showed that the values of experimental disintegration kinetic constant, Ko, through the analysis of Somerville index, as function of time. Increased, the disintegration time was drastically reduced. The calculation of the disintegration kinetic constant (modelled Ko), extracted from the Rayleigh’s dissipation function, showed a good correlation with the experimental values using the evolution of the Somerville index or with the dissipated energy

Effects of DMPP on the growth and chemical composition of ryegrass (Lolium perenne L.) raised on calcareous soil

Se llevó a cabo un experimento de 406 días en macetas para evaluar el nuevo inhibidor de la nitrificación, 3,4-dimetilpirazol fosfato (DMPP), añadido a purines de cerdo. Se utilizaron macetas que contenían tierra franca calcárea que fueron sujetas a los siguientes tratamientos: sin purín, 73,7; 147,3 y 221 cm3 de purín por maceta, todas con o sin tratamiento de DMPP. A los 18 días las macetas fueron sembradas con Lolium perenne L. El mayor rendimiento (36,3 g maceta-1) se obtuvo para el tratamiento con la dosis superior de purín y DMPP, siendo un 7,4% superior al mismo tratamiento sin inhibidor y un 46,1% superior al tratamiento control. Las plantas tratadas con dosis alta y mediana, más el DMPP, absorbieron el 70% del total del N durante la primera fase del experimento (104 días) mientras que sin inhibidor absorbieron el 55,3 y el 62% respectivamente. Se observó una reducción significativa del 17% en el N lixiviado en los tratamientos sin cultivo al aplicar DMPP. El inhibidor aumentó significativamente la eficiencia agronómica del purín (g materia seca g-1 N aplicado).