Pareto-Improving Optimal Capital and Labor Taxes

We study Pareto-optimal scal policy in a model with agents who are heterogeneous in their labor productivity and wealth. We show a natural modi cation of the standard Ramsey problem to guarantee that long-run capital taxes are zero. We focus on Paretoimproving policies and we nd that a gradual reform is crucial in achieving a Pareto improvement: labor taxes should be cut and capital taxes should remain high for a very long time before reaching zero. Therefore, the long-run optimal tax mix is the opposite of the short- and medium-run one. This policy redistributes wealth in favor of workers so that all agents bene t, and it favors quick capital growth after the reform. The labor tax cut is nanced by de cits which lead to a positive level of government debt in the long run, reversing the standard prediction that the government accumulates savings in models with optimal capital taxes. The welfare bene ts from the tax reform are relatively large and they can be shifted entirely to capitalists or workers by varying the length of the transition. We address a number of technical issues such as su ciency of Lagrangian solutions in a Ramsey problem, relation of Pareto-improving allocations with welfare functions, asymptotic behavior, and solution algorithms

In search of a theory of debt management

A growing literature integrates debt management into models of optimal fiscal policy. One promising theory argues the composition of government debt should be chosen so that fluctuations in its market value offsets changes in expected future deficits. This complete market approach to debt management is valid even when governments only issue non-contingent bonds. Because bond returns are highly correlated it is known this approach implies asset positions which are large multiples of GDP. We show, analytically and numerically, across a wide range of model specifications (habits, productivity shocks, capital accumulation, persistent shocks, etc) that this is only one of the weaknesses of this approach. We find evidence of large fluctuations in positions, enormous changes in portfolios for minor changes in maturities issued and no presumption it is always optimal to issue long term debt and invest in short term assets. We show these extreme, volatile and unstable features are undesirable from a practical perspective for two reasons. Firstly the fragility of the optimal portfolio to small changes in model specification means it is frequently better for fear of model misspecification to follow a balanced budget rather than issue the optimal debt structure. Secondly we show for even miniscule levels of transaction costs governments would prefer a balanced budget rather than the large and volatile positions the complete market approach recommends. We conclude it is difficult to insulate fiscal policy from shocks using the complete markets approach. Due to the yield curve’s limited variability maturities are a poor way to substitute for state contingent debt. As a result the recommendations of this approach conflict with a number of features we believe are integral to bond market incompleteness e.g. allowing for transaction costs, liquidity effects, robustness etc. Our belief is that market imperfections need to be explicitly introduced into the model and incorporated into the portfolio problem. Failure to do so means that the complete market approach applied in an incomplete market setting can be seriously misleading

Long Term Government Bonds

We study the impact of debt maturity on optimal fiscal policy by focusing on the case where the government issues a bond of maturity N > 1: Isolating these effects helps provide insight into the construction of optimal government debt portfolios. We find long bonds may not complete the market even in the absence of uncertainty, generate an incentive to twist interest rates and induce additional tax volatility compared to short term bonds. By focusing just on the issuance of long bonds we show that as well as their well known advantage in providing fiscal insurance long bonds also have less attractive features that induce additional tax volatility. In the case of long bonds, governments induce tax volatility in order to twist interest rates at maturity. This interest rate twisting effect is what makes optimal debt management models so difficult to solve computationally as the state space rapidly becomes cumbersome due to the need to keep track of promises about future tax rates. We provide an alternative institutional setup (\independent powers\) that eliminates this problem offering a simpler solution method. Introducing maturity requires making more institutional assumptions than is the case for one period bonds. In particular assumptions have to be made whether the government does or doesn't buy back each period all outstanding debt irrespective of maturity and whether long bonds pay coupons. This is important as the literature to date makes assumptions that are diametrically opposite to what is observed in practice. We show that this is an important divide as if we model optimal policy under the empirically motivated assumption that governments do not buyback bonds until maturity then long bonds induce additional tax volatility due to the existence of N period roll over cycles. These can be reduced in magnitude by the government issuing long bonds that pay coupons although because coupons reduce the duration of a bond below its maturity this does compromise the ability of long bonds to provide fiscal insurance

A Short Note on Optimal Debt Management under Asymmetric Information

We show that under asymetric information, if the government holds advanced information relative to the investors.some debt management policies may lead to bond market instability. The In particular, we show that the repurchase/reissuance strategy assumd in most of the current debt management literature would cause such a crisis and it would be therefore highly suboptimal.of a bond below its maturity this does compromise the ability of long bonds to provide fiscal insurance

Excitonic giant Zeeman effect in GaN:Mn^3+

We describe a direct observation of the excitonic giant Zeeman splitting in (Ga,Mn)N, a wide-gap III-V diluted magnetic semiconductor. Reflectivity and absorption spectra measured at low temperatures display the A and B excitons, with a shift under magnetic field due to s,p-d exchange interactions. Using an excitonic model, we determine the difference of exchange integrals between Mn^3+ and free carriers in GaN, N_0(alpha-beta)=-1.2 +/- 0.2 eV. Assuming a reasonable value of alpha, this implies a positive sign of beta which corresponds to a rarely observed ferromagnetic interaction between the magnetic ions and the holes.Comment: 4 pages, 4 figure

Molecular epidemiology of domestic and sylvatic Trypanosoma cruzi infection in rural northwestern Argentina

Genetic diversity of Trypanosoma cruzi populations and parasite transmission dynamics have been well documented throughout the Americas, but few studies have been conducted in the Gran Chaco ecoregion, one of the most highly endemic areas for Chagas disease, caused by T. cruzi. In this study, we assessed the distribution of T. cruzi lineages (identified by PCR strategies) in Triatoma infestans, domestic dogs, cats, humans and sylvatic mammals from two neighbouring rural areas with different histories of transmission and vector control in northern Argentina. Lineage II predominated amongst the 99 isolates characterised and lineage I amongst the six isolates obtained from sylvatic mammals. T. cruzi lineage IIe predominated in domestic habitats; it was found in 87% of 54 isolates from Tr. infestans, in 82% of 33 isolates from dogs, and in the four cats found infected. Domestic and sylvatic cycles overlapped in the study area in the late 1980s, when intense domestic transmission occurred, and still overlap marginally. The introduction of T. cruzi from sylvatic into domestic habitats is likely to occur very rarely in the current epidemiological context. The household distribution of T. cruzi lineages showed that Tr. infestans, dogs and cats from a given house compound shared the same parasite lineage in most cases. Based on molecular evidence, this result lends further support to the importance of dogs and cats as domestic reservoir hosts of T. cruzi. We believe that in Argentina, this is the first time that lineage IIc has been isolated from naturally infected domestic dogs and Tr. infestans.Fil: Cardinal, Marta Victoria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Lauricella, Marta A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C.G. Malbrán”. Instituto Nacional de Parasitología “Dr. M. Fatala Chabén”; ArgentinaFil: Ceballos, Leonardo A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Lanati, Leonardo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Marcet, Paula Lorena. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Levin, Mariano Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Kitron, Uriel D.. Emory University; Estados UnidosFil: Gurtler, Ricardo Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentin

A Mark in Time Saves Nein

A method for predicting political interactions and policy outcomes based on two political theorems is presented and illustrated with an examination of the decision to merge the two German currencies. Political perceptions and actions are anticipated by combining the substantive knowledge of area experts with the theoretical insights embedded in the median voter theorem and a monotonicity theorem that links expectations to probabilistic statements of action. The proposed model has proven accurate about 90 percent of the time. The proposed forecasting method identifies a sequential strategy that may have been followed by Chancellor Kohl in forging the coalition needed to merge successfully the two German currencies. Using comparative statics, the analysis suggests how subtle and sophisticated Chancellor Kohl had to be to succeed in getting the policy outcome he desired despite stiff opposition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66924/2/10.1177_019251219201300106.pd

Energy audit of irrigation networks

The relationship between water and energy in water distribution systems (WDS) has been a growing concern among energy and water experts. Among the different strategies to improve water¿energy efficiency in water distribution networks, energy audits are of paramount importance as they quantify water flow requirements, the amount of energy consumed to meet demand and leakage and friction losses. Previous work has presented the energy audit process for urban WDS and this energy audit is extended to irrigation networks here. This work analyses the most common types of irrigation emitters (sprinklers and pressure compensating and non-pressure compensating drippers), hydrant specifications, irrigation management systems (on-demand or rigid scheduled), and energy losses due to friction in pipes, control valves and irrigation hydrants. The energy audit does not assess whether management of the network is optimal, but analyses the energy consumption. Some of the performance indicators have already been defined for agricultural water networks, some are identical to those of urban WDS, but in addition, a new one is presented that disaggregates the energy dissipated into three terms, energy losses in pipelines, in hydraulic valves and in irrigation hydrants. These indicators show information necessary to better understand the performance of the irrigation network under study, to carry out a deep analysis of energy consumption and to allow for comparison with similar systems. The paper presents the analysis of a real case study conducted on the irrigation network of the garden of the Universidad Politécnica de ValenciaPardo, MA.; Manzano Juarez, J.; Cabrera Marcet, E.; García Serra, J. (2013). Energy audit of irrigation networks. Biosystems Engineering. 115(1):89-101. doi:10.1016/j.biosystemseng.2013.02.005S89101115

CD8α is expressed by human monocytes and enhances FcγR-dependent responses

Abstract Background CD8α enhances the responses of antigen-specific CTL activated through TCR through binding MHC class I, favoring lipid raft partitioning of TCR, and inducing intracellular signaling. CD8α is also found on dendritic cells and rat macrophages, but whether CD8α enhances responses of a partner receptor, like TCR, to activate these cells is not known. TCR and FcR, use analogous or occasionally interchangeable signaling mechanisms suggesting the possibility that CD8α co-activates FcR responses. Interestingly, CD8α+ monocytes are often associated with rat models of disease involving immune-complex deposition and FcR-mediated pathology, such as arthritis, glomerulonephritis, ischaemia, and tumors. While rat macrophages have been shown to express CD8α evidence for CD8α expression by mouse or human monocytes or macrophages was incomplete. Results We detected CD8α, but not CD8β on human monocytes and the monocytic cell line THP-1 by flow cytometry. Reactivity of anti-CD8α mAb with monocytes is at least partly independent of FcR as anti-CD8α mAb detect CD8α by western blot and inhibit binding of MHC class I tetramers. CD8α mRNA is also found in monocytes and THP-1 suggesting CD8α is synthesized by monocytes and not acquired from other CD8α+ cell types. Interestingly, CD8α from monocytes and blood T cells presented distinguishable patterns by 2-D electrophoresis. Anti-CD8α mAb alone did not activate monocyte TNF release. In comparison, TNF release by human monocytes stimulated in a FcR-dependent manner with immune-complexes was enhanced by inclusion of anti-CD8α mAb in immune-complexes. Conclusion Human monocytes express CD8α. Co-engagement of CD8α and FcR enhances monocyte TNF release, suggesting FcR may be a novel partner receptor for CD8α on innate immune cells.</p

Widespread inter- and intra-domain horizontal gene transfer of d-amino acid metabolism enzymes in eukaryotes

Analysis of the growing number of available fully-sequenced genomes has shown that Horizontal Gene Transfer (HGT) in eukaryotes is more common than previously thought. It has been proposed that genes with certain functions may be more prone to HGT than others, but we still have a very poor understanding of the selective forces driving eukaryotic HGT. Recent work uncovered that D-amino acid racemases have been commonly transferred from bacteria to fungi, but their role in the receiving organisms is currently unknown. Here, we set out to assess whether D-amino acid racemases are commonly transferred to and between eukaryotic groups. For this we performed a global survey that used a novel automated phylogeny-based HGT-detection algorithm (Abaccus). Our results revealed that at least 7.0% of the total eukaryotic racemase repertoire is the result of inter- or intra-domain HGT. These transfers are significantly enriched in plant-associated fungi. For these, we hypothesize a possible role for the acquired racemases allowing to exploit minoritary nitrogen sources in plant biomass, a nitrogen-poor environment. Finally, we performed experiments on a transferred aspartate-glutamate racemase in the fungal human pathogen Candida glabrata, which however revealed no obvious biological role