Domain wall propagation due to the synchronization with circularly polarized microwaves

Finding a new control parameter for magnetic domain wall (DW) motion in magnetic nanostructures is important in general and in particular for the spintronics applications. Here, we show that a circularly polarized magnetic field (CPMF) at GHz frequency (microwave) can efficiently drive a DW to propagate along a magnetic nanowire. Two motion modes are identified: rigid-DW propagation at low frequency and oscillatory propagation at high frequency. Moreover, DW motion under a CPMF is equivalent to the DW motion under a uniform spin current in the current perpendicular to the plane magnetic configuration proposed recently by Khvalkovskiy et al. [Phys. Rev. Lett. 102, 067206 (2009)], and the CPMF frequency plays the role of the current

Os Efeitos da CPMF sobre a Intermediação Financeira

The purpose of this article is to empirically evaluate the impact of the Provisional Contribution on Financial Turnover (CPMF) in the financial intermediation. More specifically, it analyzes the consequences of the introduction of the CPMF on: a) the number of checks issued; b) the CPMF base; c) the volume of M1; d) the allocation of resources between time deposits and investment funds and e) the bank interest spread. The main conclusions are: i) the CPMF erodes its own tax base; ii) the CPMF reduced the number of checks used in the economy; iii) the effect of the CPMF on the M1 is positive, although not very significant; iv) considering portfolio allocation, the CPMF fostered a transference of time deposits to investment funds; v) the CPMF increases the gross banking spread and reduces the net spread, thus leading to lower returns to all the agents involved in the financial intermediation process namely, the loan undertakers, savers and the financial intermediaries.

Os Impactos Econômicos da CPMF: Teoria e Evidência

Este trabalho tem como objetivo estudar os impactos econômicos da CPMF na economia brasileira, e para isto está dividido em três blocos. No primeiro a CPMF é analisada sob a ótica da teoria econômica. No segundo é discutida a experiência internacional com impostos similares à CPMF. No terceiro a experiência brasileira é examinada com o auxílio dos dois blocos anteriores. Segundo a teoria econômica, a CPMF causaria a elevação dos juros reais de modo desproporcional a outros impostos, o que seria o resultado da inclusão da rotatividade de ativos em sua base de incidência. Esta deficiência em sua concepção afetaria negativamente, e de forma desproporcional à sua arrecadação, os níveis de capital, produção e salários. Ela também causaria o aumento das despesas do governo com pagamento de juros, o que levaria parte de sua receita a ser fictícia. A CPMF causaria desintermediação e iliquidez nos mercados financeiros, desincentivando o ressurgimento do crédito. A arrecadação comportar-se-ia de acordo com uma curva de Laffer, com elevadas perdas de peso morto, particularmente quando comparadas à pequena receita resultante. Resultados empíricos confirmam que tais conclusões seriam aplicáveis ao caso brasileiro. A teoria econômica, a experiência internacional e a evidência brasileira revelam, portanto, que a CPMF apresenta significativas deficiências como instrumento de arrecadação.CPMF, ITF, IDB, desintermediação, iliquidez, curva de Laffer

BAD Taxation: Disintermediation and Illiquidity in a Bank Account Debits Tax Model

This paper uses a dynamic general equilibrium model to study the economic effects of bank account debits (BAD) taxation. Australia and various Latin American countries have levied or levy BAD taxes. Aspects such as financial disintermediation, market illiquidity, and impacts on dividend and interest rates are considered. Part of the BAD tax revenue may be fictitious, due to increased interest payments on government debt. The Brazilian BAD tax (CPMF) experience is evaluated. The empirical analysis confirms some theoretical predictions. Incidence base over GDP appears to be sensitive to the tax rate, possibly engendering a Laffer curve. The tax may also cause real interest rates to increase. Furthermore, the deadweight losses are relatively large, even if revenues are small. The theoretical and empirical results suggest that the BAD tax is not adequate for revenue collection.Bank Account Debits Tax, BAD Tax, Financial Transactions Tax, FTT, Currency Transaction Tax, CTT, Automated Payment Transaction Tax, APT Tax, CPMF, Disintermediation, Illiquidity

Os Impactos Econômicos da CPMF: Teoria e Evidência

This paper aims to study the economic impacts of the CPMF in the Brazilian economy and was divided in three parts. In the first part, the CPMF is analyzed under the scope of the economic theory. In the second part, the international experience with taxes similar to the CPMF is discussed. At the end, the Brazilian experience is analyzed, considering the contributions of the two previous parts. According to the economic theory, the CPMF should increase real interest rates unproportionally to other taxes, as a result of the inclusion of asset turnover in its incidence base. This conceptual deficiency would negatively affect, unproportionally to its tax collection, the level of capital, production and wages. It would also cause the increase of government expenditures through interest payments, implying a fictious amount of revenues. The CPMF would cause disintermediation and illiquidity in the financial markets, hindering the resurgence of credit in Brazil. The tax collection would follow a Laffer curve, with high deadweight losses, particularly when compared to its small revenue. Empirical results confirm that those conclusions would be valid in the Brazilian case. The economic theory, the international experience and the Brazilian evidence reveal, therefore, that the CPMF presents significant inefficiencies as a tax collection instrument.

Using a Money Demand Model to Evaluate Monetary Policies in Brazil

This paper uses a money demand model to evaluate monetary policies under different regimes in Brazil. The consistency between monetary liquidity and the inflation rate path is considered. The concept is applied to the Brazilian case by modeling M 1 and its components. Based on unit root and cointegration tests, a growth-rate model is chosen, which considers all the interventions that happened during the sample period (1980-1999). It is shown that a variable seasonal pattern, which is a linear function of the nominal interest rate, increases the model ability to explain seasonal changes in the money demand. Despite the economic instability that marked Brazilian economic history during the last two decades, the model shows good fit and predictive power. Finally, it is shown that unsuccessful macroeconomic stabilization programs were marked by excessive liquidity, with money supply exceeding expected conditional money demand during intervention periods. The results suggest that to track monetary aggregates can be useful to policy makers even under a regime where interest rates are the main policy instrument.

Une définition inadaptée

Cet article est extrait du dossier « Vers une nouvelle définition du musée ? » dirigé par Ewa Maczek, directrice par intérim de l'Ocim. La définition du musée proposée depuis 2007 par l'Icom fait référence dans la sphère muséale mondiale. Si la volonté de faire évoluer cette définition fait sens, la proposition du Comité pour la Définition du musée, perspectives et potentiels (MDPP) de l'Icom a surpris bon nombre de professionnels et d'institutions, et tout particulièrement en France. La lettre de l'Ocim leur a ouvert ses pages pour qu’ils partagent leurs réactions

Current and Future Constraints on Primordial Magnetic Fields

We present new limits on the amplitude of potential primordial magnetic fields (PMFs) using temperature and polarization measurements of the cosmic microwave background (CMB) from Planck, BICEP2/Keck Array, POLARBEAR, and SPTpol. We reduce twofold the 95% CL upper limit on the CMB anisotropy power due to a nearly-scale-invariant PMF, with an allowed B-mode power at $\ell=1500$ of $D_{\ell=1500}^{BB} < 0.071 \mu K^2$ for Planck versus $D_{\ell=1500}^{BB} < 0.034 \mu K^2$ for the combined dataset. We also forecast the expected limits from soon-to-deploy CMB experiments (like SPT-3G, Adv. ACTpol, or the Simons Array) and the proposed CMB-S4 experiment. Future CMB experiments should dramatically reduce the current uncertainties, by one order of magnitude for the near-term experiments and two orders of magnitude for the CMB-S4 experiment. The constraints from CMB-S4 have the potential to rule out much of the parameter space for PMFs.Comment: Submitted to ApJ, 10 page