176,095 research outputs found
Jon C. Romer
No full textProfessor Jon Romer standing at a piano, holding a Mozart score, and wearing checkered slacks
Dynamic Scoring in a Romer-style Economy
No full textThis paper explores the dynamic behavior of a Romer-style endogenous growth model, analyzing how changes in tax rates affect government revenue in the short run and the long run. I show that in this environment lowering taxes on financial income is unlikely to stimulate tax revenue in the long run and has modest effects on the tax base, contrary to some other studies of the dynamic response of revenue to tax rates. Calibrations of the model that suggest Laffer curve effects can be substantial require implausibly low values for the elasticity of substitution between varieties of intermediate goods. For more plausible parameter values, I find that around 20% of a tax cut would be self-financing due to an expansion in the tax base.
Cu, Zn, and Cd acquisition by two spinach cultivars depending on P nutrition and root exudation
No full textWithin a spectrum of 11 spinach cultivars (cvs) differences in the Cu. Zn, and Cd contents of shoots had been noticed. The aim of this study was therefore to analyze in more detail the acquisition of Cu, Zn, and Cd by the most differing cultivars (Tabu and Monnopa) in dependence on P nutrition. The plants were grown in a low phosphorus Luvisol (pH 6.3: total contents Cu: 89, Zn: 297, Cd: 1.4 mg kg(-1)) with two phosphorus levels in pots under natural conditions. For the determination of inflow, root length/ shoot weight ratio and of the Cu, Zn, and Cd concentration in the soil solution (rhizosphere) plants were harvested 26 and 40 days after sowing. Root exudation of organic acids of the two cvs was measured 35 days after growing in quartz sand with different P supply. Both cultivars responded to P fertilizer by doubling their shoot weight. With increased P supply (0.68-0.77% P in shoot-DM) both cultivars showed similar heavy metal contents in the shoot resulting from similar root length/shoot weight ratios (RSR) and net uptake rates of the three elements as well as the same element concentrations in the rhizosphere soil solution. Under P deficiency, however, cv. Tabu (0.52% P in shoot-DM) showed in comparison with cv. Monnopa (0.48% P) higher Cu, Zn, and Cd contents of shoots although its RSR was smaller than that of cv. Monnopa. However, the inflow for Cu was higher and for Zn and Cd significantly higher compared with cv. Monnopa. This result of cv. Tabu corresponded with higher concentrations of Cu, Zn, and Cd of its rhizosphere soil solution, and its higher exudation rates of oxalate, citrate, and malate (3.9; 1.0; 0.7 nmol cm(-1) h(-1)). The corresponding values for cv. Monnopa were: 1.7: 0.3; 0.4 nmol cm-l h-l. The mobilization of Cu, Zn, and Cd by the excreted organic acids seems to be responsible for the higher Cu, Zn, and Cd inflow of cv. Tabu
Neglected P and K fertilization in organic farming reduces N-2 fixation and grain yield in a red clover-oat rotation
No full textN-2 fixation is the most important N source in organic farming. An insufficient P, K, and S supply to legumes may reduce their N-2 fixation capacity. Consequently, the total yield of plant production may also be reduced. This problem was studied in a pot experiment with red clover followed by oat. Soil was taken from a field where organic farming had been practiced for more than 30 years without applying any mineral fertilizers or buying additional fodder. The soil (luvisol from loess) was characterized by: pH (CaCl2) 5.4 lactate-soluble (CAL) P 5 mg kg(-1) and K 110 mg kg(-1). 6 kg dry soil were mixed with 400 mg P applied as (i) triplesuperphosphate (TSP), (ii) rock phosphate (RP) or (iii) compost from organic household residues (BAK). An additional treatment (iv) with TSP received 1000 mg K as K2SO4 (TSP+K) and an additional treatment with RP (v) received only 200 mg P (RP/2). A control treatment received no fertilizer. P application significantly improved the P nutritional status of the plants (P content) and increased the N amount in the shoots of red clover (with 400 mg P per pot by 64% to 139% as compared to the control) and the dry matter (DM) yield by 60% to 130%. No significant differences between TSP and RP were found. The application of BAK resulted in a significantly higher N yield than the application of RP and TSP. The treatment TSP+K resulted in the highest DM yield (230%), removal of P was 343%, of K 228%, and of N 239% as compared to the control plants. This indicates a synergistic effect of P, K, and S on N-2 fixation, which was also found with BAK. Oat grown after red clover increased its grain yield by 132% (200 mg P as RP) to 165% (400 mg P treatments). This was mainly due to a higher P uptake (up to 172%) and a higher N uptake (up to 172%) as compared to the control
Idéologie et langage en Italie
No full textIdeologie et langage en Italie (L. Formigari) The author notes the influence of the Ideologists, after that of Condillac, on linguistic studies in Italy, in spite of the suspicion aroused by the materalist views that are supposed to accompany their philosophical positions. As early as 1796, there appears a trend of thought close to Ideology, which aims at theorizing on the relationship between language, society and culture. This was a fundamental problem for a country that had not yet found its linguistic or political unity. The substantial bibliography in this article brings up numerous points concerning research on the influence of the Ideologists.Formigari Lia, Romer C. Idéologie et langage en Italie. In: Histoire Épistémologie Langage, tome 4, fascicule 1, 1982. Les idéologues et les sciences du langage. pp. 137-141
How large are the effects of tax changes?
No full textWe use the time series of shifts in U.S. Federal tax liabilities constructed by Romer and Romer to estimate tax multipliers. Differently from the single-equation approach adopted by Romer and Romer, our estimation strategy (a Var that includes output, government spending and revenues, inflation and the nominal interest rate) does not rely upon the assumption that tax shocks are orthogonal to each other as well as to lagged values of other macro variables. Our estimated multiplier is much smaller: one, rather than three at a three-year horizon. When we split the sample in two sub-samples (before and after 1980) we find, before 1980, a multiplier whose size is never greater than one, after 1980 a multiplier not significantly different from zero. Following the findings in Bohn (1998), we also experiment with a model that includes debt and the non-linear government budget constraint. We find that, while in general not very important, the non-linearity that arises from the budget constraint makes a difference after 1980, when the response of fiscal variables to the level of the debt becomes stronger.
Influence of iron content in sewage sludges on parameters of phosphate availability in arable soils
No full textThe use of iron salts for the P elimination in sewage plants is widely used. But it is not clear whether the P availability in arable soils is negatively influenced by iron compounds or not. The aim of the investigations was, therefore, to study the influence of two sewage sludges with a high and a low Fe content respectively on P sorption and phosphate concentration (P-i) in the soil solution after application of CaHPO4 or sewage sludge to 5 loamy and 4 sandy soils (pot experiments and 1 silty loam (field experiment)). Soils were analyzed 1, 6, and 13 months after P application. Sludge Ga contained 12 kg P and 65 kg Fe (t DM)(-1) (P : Fe = 1 : 5.4) and sludge Sh 25 kg P and 39 kg Fe (t DM)(-1) (P : Fe = 1 : 1.5). The basic P application wits 60 kg P ha(-1) (= 30 mg P (kg soil)(-1) in the pot experiment, as sludge or as CaHPO4). P uptake by maize was determined in a separate pot experiment with a loamy soil and the same P application rate. The P sorption capacity remained similar in all soils after application of sludge Sh (P : Fe = 1:1.5) compared with soils without sludge, however, after application of sludge Ga the P sorption increased by 16% (0-59%). After application of sludge Sh the mean P-i concentration increased in loamy soils by 34% and in sandy soils by 15% On the other hand the P-i concentration decreased after applying sludge Ga by 13% and 36% as compared to the controls of the respective soils. In the field experiment the Pi concentration of plots with a high P level (50 mg lactate soluble P (kg soil)(-1)) was also significantly decreased after application of 10 t sludge Ga (126 kg P ha(-1)) in comparison with triple phosphate. One month after the application of increasing amounts of sludge Go (5, 10, 15 t DM ha(-1)) both the concentration of oxalate-soluble Fe in the soil and the P sorption were increased. The elevated relationship between these two parameters was highly significant (r(2) = 0.6 - 0.97). Plant uptake of P was less after application of sludge Ga than after application of sludge Sh and much less than P uptake from CaHPO4. Sewage sludges with a P: Fe ratio of 1 : 5 should net be recommended for agricultural use, as the P availability is significantly reduced. Iron salts should not be used for conditioning of sludges
Phosphorus fertilization effect of sewage sludges treated with iron compounds
No full textThe result of waste water treatment with iron salts are sewage sludges with higher P but also Fe contents. The effect of such sludges on P availability in soils is not clear and was, therefore, compared with CaHPO4 as a P mineral fertilizer. In experiments (Mitscherlich pots, 6 kg soil) two sandy soils (pH 4.3 and 4.9), two luvisols ( pH 6.3 and 7.2), a loess (13 % CaCO3), and quartz sand all differing in their P status were treated with two sewage sludges which differed in their molar Fe:P ratios (sludge GO: 1:0.3, sludge Sh: 1:1.2). For sludge GO the P elimination had been carried out with FeSO4 and the sludge was stabilized with FeCl3 + Ca(OH)(2) (filter press). For sludge Sh P was eliminated by FeCl3 in the aerobic basin. The first crop was maize (total shoot dry matter), the second red clover. In case of sludge Sh both crops took up in comparison to CaHPO4 the same amount of P from all substrates with the exception of quartz sand. The effect of sludge GO was quite different: from the neutral luvisol soils maize was able to take up only 64-82 % P and red clover 77-82 % P only as compared to CaHPO4. On the sandy soils maize and red clover grew after sludge GO as good or better than after CaHPO4 application and P uptake was quite similar (83-106 %). This result was concomitant to an increase of pH values (from 4.3 to 4.9, 4.9 to 5.6, respectively). The negative efficiency of P uptake in heavy soils after application of sludge GO resulted from an increase of P sorption and decrease of orthophosphate concentration in soil solution. This sludge contains a high proportion of iron hydroxides/oxides with free sorption sites for P. In future P elimination from waste water should be done without iron salts. At least during the process of conditioning no Fe salts should be used
International Master on Community Protection and Safety Promotion: a key challenge to world wide phenomenon
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