TrusNet: Peer-to-Peer Cryptographic Authentication

Originally, the Internet was meant as a general purpose communication protocol, transferring primarily text documents between interested parties. Over time, documents expanded to include pictures, videos and even web pages. Increasingly, the Internet is being used to transfer a new kind of data which it was never designed for. In most ways, this new data type fits in naturally to the Internet, taking advantage of the near limit-less expanse of the protocol. Hardware protocols, unlike previous data types, provide a unique set security problem. Much like financial data, hardware protocols extended across the Internet must be protected with authentication. Currently, systems which do authenticate do so through a central server, utilizing a similar authentication model to the HTTPS protocol. This hierarchical model is often at odds with the needs of hardware protocols, particularly in ad-hoc networks where peer-to-peer communication is prioritized over a hierarchical model. Our project attempts to implement a peer-to-peer cryptographic authentication protocol to be used to protect hardware protocols extending over the Internet. The TrusNet project uses public-key cryptography to authenticate nodes on a distributed network, with each node locally managing a record of the public keys of nodes which it has encountered. These keys are used to secure data transmission between nodes and to authenticate the identities of nodes. TrusNet is designed to be used on multiple different types of network interfaces, but currently only has explicit hooks for Internet Protocol connections. As of June 2016, TrusNet has successfully achieved a basic authentication and communication protocol on Windows 7, OSX, Linux 14 and the Intel Edison. TrusNet uses RC-4 as its stream cipher and RSA as its public-key algorithm, although both of these are easily configurable. Along with the library, TrusNet also enables the building of a unit testing suite, a simple UI application designed to visualize the basics of the system and a build with hooks into the I/O pins of the Intel Edison allowing for a basic demonstration of the system

School Quality and the Distribution of Male Earnings in Canada

Using quantile regressions, this paper provides evidence that the relationship between school quality and wages varies across points in the conditional wage distribution and educational attainment levels. Although smaller classes generally have a positive return for individuals at high quantiles, they have a negative impact at low quantiles. Similarly, while more highly paid teachers benefit drop-outs at high quantiles and graduates at low quantiles, they have a negative return for all other quantile-education groups. The results presented in this paper also suggest that the optimal school for high school graduates is likely smaller than for high school drop-outs.school quality, quantiles, wages

Generalized cable formalism to calculate the magnetic field of single neurons and neuronal populations

Neurons generate magnetic fields which can be recorded with macroscopic techniques such as magneto-encephalography. The theory that accounts for the genesis of neuronal magnetic fields involves dendritic cable structures in homogeneous resistive extracellular media. Here, we generalize this model by considering dendritic cables in extracellular media with arbitrarily complex electric properties. This method is based on a multi-scale mean-field theory where the neuron is considered in interaction with a "mean" extracellular medium (characterized by a specific impedance). We first show that, as expected, the generalized cable equation and the standard cable generate magnetic fields that mostly depend on the axial current in the cable, with a moderate contribution of extracellular currents. Less expected, we also show that the nature of the extracellular and intracellular media influence the axial current, and thus also influence neuronal magnetic fields. We illustrate these properties by numerical simulations and suggest experiments to test these findings.Comment: Physical Review E (in press); 24 pages, 16 figure

Kramers-Kronig relations and the properties of conductivity and permittivity in heterogeneous media

The macroscopic electric permittivity of a given medium may depend on frequency, but this frequency dependence cannot be arbitrary, its real and imaginary parts are related by the well-known Kramers-Kronig relations. Here, we show that an analogous paradigm applies to the macroscopic electric conductivity. If the causality principle is taken into account, there exists Kramers-Kronig relations for conductivity, which are mathematically equivalent to the Hilbert transform. These relations impose strong constraints that models of heterogeneous media should satisfy to have a physically plausible frequency dependence of the conductivity and permittivity. We illustrate these relations and constraints by a few examples of known physical media. These extended relations constitute important constraints to test the consistency of past and future experimental measurements of the electric properties of heterogeneous media.Comment: 17 pages, 2 figure

Macroscopic models of local field potentials and the apparent 1/f noise in brain activity

The power spectrum of local field potentials (LFPs) has been reported to scale as the inverse of the frequency, but the origin of this "1/f noise" is at present unclear. Macroscopic measurements in cortical tissue demonstrated that electric conductivity (as well as permittivity) is frequency dependent, while other measurements failed to evidence any dependence on frequency. In the present paper, we propose a model of the genesis of LFPs which accounts for the above data and contradictions. Starting from first principles (Maxwell equations), we introduce a macroscopic formalism in which macroscopic measurements are naturally incorporated, and also examine different physical causes for the frequency dependence. We suggest that ionic diffusion primes over electric field effects, and is responsible for the frequency dependence. This explains the contradictory observations, and also reproduces the 1/f power spectral structure of LFPs, as well as more complex frequency scaling. Finally, we suggest a measurement method to reveal the frequency dependence of current propagation in biological tissue, and which could be used to directly test the predictions of the present formalism

The Location of Women's Prisons and the Deterrence Effect of 'Harder' Time

Most studies of the deterrence effect of incarceration treat a year in prison as having the same deterrence effect regardless of the conditions of incarceration. In contrast, we estimate both the impact of custody rate and prison location changes on female crime rates. We take advantage of the natural experiment created by recent expansions of the female penal system; many states witnessed a rapid doubling of prison capacity. The physical expansion of the penal system decreased the distance to prisons for some cities while increasing it for others. Movement in both directions is particularly helpful because it ensures that we are not identifying relationships off coincidental one-directional trends. Our results suggest that prison location has a sizable deterrence effect. Increasing the average distance to a woman’s prison by 40 miles reduces the female violent crime rate by approximately 7 percent.

Against All Odds: The Surprising Labor Market Success of Young Mexican Women

Using the NLSY, we find that young Mexican women earn 11.7% less than young White women while young Black women earn 19.2% less than young White women. Although young Mexican women earn less than young White women, they do surprisingly well compared to young Black women. We show that while it is crucially important to account for actual labor market experience, it does not matter if we account for childbirth patterns, and non-linearities in the experience profile. We further show that low labor force attachment is the most important determinant of the Black-White wage differential for young women while education is the most important explanation for the Mexican-White wage gap for young women.

Does Single Parenthood Increase the Probability of Teenage Promiscuity, Drug Use and Crime?

There is longstanding evidence that children raised by single parents are more likely to perform poorly in school and partake in ‘deviant’ behaviors such as smoking, sex, substance use and crime at young ages. However, as of yet there is not widespread evidence or agreement as to whether or not the timing of the marital disruption differentially impacts youth outcomes. Using the National Longitudinal Survey of Youth (NLSY) and the NLSY Young Adult Supplement, we find that the longer the biological father remains in the household the lower the probability that youth engage in sexual activity. In contrast, it is youth whose fathers are never present who are more likely to be convicted of a crime, youth whose fathers leave during adolescence who are more likely to drink alcohol and use illegal drugs and youth whose fathers leave during childhood who are more likely to smoke cigarettes.Family Structure; Marital Dissolution; Youth Outcomes

The Racial Wage Gap: The Importance of Labor Force Attachment Differences Across Black, Mexican and White Men

Labor market attachment differs significantly across black, Mexican and white men; black and Mexican men are more likely to experience unemployment and out of the labor force spells than are white men. While it has long been agreed that potential experience is a poor proxy of actual experience for women, many view it as an acceptable approximation for men. Using the NLSY, this paper documents the substantial difference between potential and actual experience for both black and Mexican men. We show that the fraction of the black/white and Mexican/white wage gaps that are explained by differences in potential experience are very different than the fraction of the racial wage gaps that are explained by actual (real) experience differences. We further show that the fraction of the racial wage gap explained by education is substantially overstated when potential experience is used instead of actual experience.Discrimination; Wages

Low cost concentrator

The key to concentrator cost effectiveness is the proper design of the reflector surface panels. The low cost concentrator reflective surface design is based on use of a thin, backsilvered mirror glass reflector bonded to a molded structural plastic substrate. This combination of reflective panel material offers excellent optical performance at low cost. The design approach, rationale for the selected configuration, and the development status are described. Reflective panel development and demonstration results are also presented