Economic Analysis of U.S. Immigration Reforms

In January 2004, President George Bush proposed the creation of a temporary worker program to allow more migrant workers to enter the US legally. This new temporary worker program would be open to undocumented workers in the US, as well as to prospective migrants currently residing abroad. The program would temporarily allow immigrants to fill jobs that, according to employers, would otherwise go unfilled at the current wage. The US Congress vetoed the presidential proposal, however, and requested a stricter enforcement of immigration law and the consequent deportation of undocumented immigrants. This study analyzes the economic effects of these immigration reforms on the US economy using an applied global general equilibrium model of migration. In this paper the global trade and migration model (GMig2) developed by Walmsley, Winters and Ahmed (2007) is modified to include a third labor category – undocumented unskilled – to reflect estimates of undocumented workers residing in the United States. The model is then used to analyze the impacts of two policy scenarios on the US economy: first, the deportation of undocumented workers currently residing in the US; and second, the legalization of undocumented agricultural workers. The first scenario is implemented through a decline in the number of undocumented workers residing in the US to zero, and a corresponding increase in the number of workers in Mexico. The second scenario is achieved by allowing undocumented workers to obtain legal status, thereby increasing their wages and productivity. We find that the deportation of undocumented workers causes a considerable loss to the US economy in terms of real GDP. Legalization of Mexican undocumented immigrants, on the other hand, is found to increase US real GDP. Hence the paper demonstrates there are clear advantages to the US economy of implementing proposals that both allow migrant workers to remain in the United States and increase the workers ability to participate freely in the US labor force as legal residents.US Undocumented Workers, Applied General Equilibrium, Political Economy,

Bandwidth aspects in second generation current conveyors

This paper discusses bandwidth problems associated with second-generation current conveyors (CCII). In particular, our work is centered in high-capacitance applications, and has been oriented for wireless optical links and applied physics. We discuss techniques for improving bandwidth in these CCIIs, and develop a new CCII structure with larger bandwidth than traditional circuits. These circuits are then compared in terms of their noise and dynamic range characteristics. A test circuit was developed to verify these different bandwidth behaviors

Quantum Key Distribution using Continuous-variable non-Gaussian States

In this work we present a quantum key distribution protocol using continuous-variable non-Gaussian states, homodyne detection and post-selection. The employed signal states are the Photon Added then Subtracted Coherent States (PASCS) in which one photon is added and subsequently one photon is subtracted. We analyze the performance of our protocol, compared to a coherent state based protocol, for two different attacks that could be carried out by the eavesdropper (Eve). We calculate the secret key rate transmission in a lossy line for a superior channel (beam-splitter) attack, and we show that we may increase the secret key generation rate by using the non-Gaussian PASCS rather than coherent states. We also consider the simultaneous quadrature measurement (intercept-resend) attack and we show that the efficiency of Eve's attack is substantially reduced if PASCS are used as signal states.Comment: We have included an analysis of the simultaneous quadrature measurement attack plus 2 figures; we have also clarified some point

Derived bracket construction and Manin products

We will extend the classical derived bracket construction to any algebra over a binary quadratic operad. We will show that the derived product construction is a functor given by the Manin white product with the operad of permutation algebras. As an application, we will show that the operad of prePoisson algebras is isomorphic to Manin black product of the Poisson operad with the preLie operad. We will show that differential operators and Rota-Baxter operators are, in a sense, Koszul dual to each other.Comment: This is the final versio

Screening of pair fluctuations in superconductors with coupled shallow and deep bands: a route to higher temperature superconductivity

A combination of strong Cooper pairing and weak superconducting fluctuations is crucial to achieve and stabilize high-Tc superconductivity. We demonstrate that a coexistence of a shallow carrier band with strong pairing and a deep band with weak pairing, together with the Josephson-like pair transfer between the bands to couple the two condensates, realizes an optimal multicomponent superconductivity regime: it preserves strong pairing to generate large gaps and a very high critical temperature but screens the detrimental superconducting fluctuations, thereby suppressing the pseudogap state. Surprisingly, we find that the screening is very efficient even when the inter-band coupling is very small. Thus, a multi-band superconductor with a coherent mixture of condensates in the BCS regime (deep band) and in the BCS-BEC crossover regime (shallow band) offers a promising route to higher critical temperatures.Comment: 8 pages, 1 figure, including supplemental material

Determinação da aderência entre resinas epoxídicas e argamassas hidráulicas

A determinação da aderência entre polímeros e argamassas coloca alguns problemas. A utilização de ensaios tradicionais como tracção directa, flexão ou corte, normalmente não permite a determinação do valor numérico da aderência. Quando o ligante é bom e a colagem é bem executada, a rotura ocorre na argamassa. Este tipo de roturas permite concluir que a aderência é superior ao valor da tensão de rotura obtida, não sendo possível dizer qual o valor numérico da aderência. Utilizando um ensaio baseado na mecânica da fractura é mais fácil a determinação da aderência. Os provetes com entalhe permitem a concentração de tensões na junta polímero/argamassa. Assim, as roturas adesivas são mais frequentes, permitindo a determinação do valor numérico da aderência. O provete escolhido para este estudo foi o DCB (“double cantilever beam”). Os materiais utilizados foram uma resina epoxídica e uma argamassa normal. Os ensaios de tracção directa das colagens entre estes dois materiais conduziram a roturas na argamassa. No entanto, nos ensaios com provetes DCB obtiveram-se sempre roturas mistas. Para a determinação da energia de fractura (Gf) é necessário conhecer o comprimento da fissura. Este parâmetro altera-se durante o ensaio, não sendo fácil a sua determinação em cada instante. Para esta determinação, utilizaram-se três métodos: emissão acústica, colocação de um deflectómetro no meio do caminho de fissura e complacência. O método da complacência revelou-se mais adequado. Outro problema é o desvio das fissuras para fora do seu caminho esperado. Para evitar estes desvios, reforçaram-se os provetes exteriormente, colando placas de aço. Assim, conseguiu-se que as roturas seguissem o caminho de propagação esperado. Por último, para evitar o reforço exterior, utilizaram-se provetes DCB com secção variável. Estes provetes comportaram-se bem durante os ensaios