Intrinsic Tunneling in Cuprates and Manganites

The most anisotropic high temperature superconductors like Bi2Sr2CaCu2O8, as well as the recently discovered layered manganite La1.4Sr1.6Mn2O7 are layered metallic systems where the interlayer current transport occurs via sequential tunneling of charge carriers. As a consequence, in Bi2Sr2CaCu2O8 adjacent CuO2 double layers form an intrinsic Josephson tunnel junction while in in La1.4Sr1.6Mn2O7 tunneling of spin polarized charge carriers between adjacent MnO2 layers leads to an intrinsic spin valve effect. We present and discuss interlayer transport experiments for both systems. To perform the experiments small sized mesa structures were patterned on top of single crystals of the above materials defining stacks of a small number of intrinsic Josephson junctions and intrinsic spin valves, respectively.Comment: 6 pages, 8 figure

Racial Profiling in the Name of National Security: Protecting Minority Travelers\u27 Civil Liberties in the Age of Terrorism

Government-sponsored ethnic and racial profiling in the form of computerized and behavioral screening initiatives implemented as a response to 9/11 has led to the subjection of minorities to increased scrutiny and suspicion in American airports. In the name of national security, safety protocols are being enacted in non-uniform ways that disproportionally infringe on minority passengers’ civil liberties and reinforce harmful racial stereotypes. Focusing on the dissonance between basic freedoms guaranteed by the United States Constitution and the security policies implemented by the federal government, this Note argues that the disparity in scrutiny received by minority travelers is counterproductive because it reinforces racism and ethnocentrism as social norms and fails to ensure a consistent level of protection for all passengers. This Note ultimately advocates for a federal government mandate that delineates a universal, race-blind standard for the level of scrutiny (and accompanying procedures) that all passengers should be subjected to while traveling aboard commercial aircraft

Media of the Fear. Terror education in the US-American TV serials 24 and Sleeper Cell

Das Erkenntnisinteresse des Artikels ist darauf gerichtet zu zeigen, wie Populäre Medienproduktionen, hier die fiktionale Fernsehserie, soziale Bilder sowie Diskurse über den Terrorismus transportieren und artikulieren. Hierzu werden die beiden US-amerikanischen Fernsehserien 24 und Sleeper Cell analysiert, die Terror-Bildungsprozesse performativ aufführen: einerseits als US-amerikanische Aussensicht auf den Terrorismus (24), andererseits als Innenansicht einer Terrorzelle (Sleeper Cell). Es handelt sich bei diesen Serien um die ersten Fernsehserien, die die permanente Terror-Bedrohung und Terror-Bekämpfung zum Leitthema machen. Diese beiden Serien sind wegweisend für die verstärkte Auseinandersetzung mit dem Terror in US-amerikanischen Fernsehserien.In this article it is discussed how popular media productions, here the fictional TV serial, articulate social pictures as well as discourses about terrorism. Moreover both TV serials 24 and Sleeper Cell are analysed. Both perform educational processes in dealing with the terrorism: on the one hand 24 gives an outside view of the terrorism, on the other hand, Sleeper Cell shows an inside view of a terror cell. These both series are the first TV serials, which make the menace by terror and the fight against terror the main theme. These series are ground breaking for the reinforced discussion with the terror in US-American TV serials

Voltage-flux-characteristics of asymmetric dc SQUIDs

We present a detailed analysis of voltage-flux V(Phi)-characteristics for asymmetric dc SQUIDs with various kinds of asymmetries. For finite asymmetry alpha_I in the critical currents of the two Josephson junctions, the minima in the V(Phi)-characteristics for bias currents of opposite polarity are shifted along the flux axis by Delta_Phi = (alpha_I)*(beta_L) relative to each other; beta_L is the screening parameter. This simple relation allows the determination of alpha_I in our experiments on YBa_2Cu_3O_(7-x} dc SQUIDs and comparison with theory. Extensive numerical simulations within a wide range of beta_L and noise parameter Gamma reveal a systematic dependence of the transfer function V_Phi on alpha_I and alpha_R (junction resistance asymmetry). As for the symmetric dc SQUID, V_Phi factorizes into g(Gamma*beta_L)*f(alpha_I,beta_L), where now f also depends on alpha_I. For \beta_L below five we find mostly a decrease of V_Phi with increasing alpha_I, which however can only partially account for the frequently observed discrepancy in V_Phi between theory and experiment for high-T_c dc SQUIDs.Comment: 4 pages, 7 figures, Applied Superconductivity Conference 2000, to be published in IEEE Trans. Appl. Supercon

Big Data and the Internet of Things

Advances in sensing and computing capabilities are making it possible to embed increasing computing power in small devices. This has enabled the sensing devices not just to passively capture data at very high resolution but also to take sophisticated actions in response. Combined with advances in communication, this is resulting in an ecosystem of highly interconnected devices referred to as the Internet of Things - IoT. In conjunction, the advances in machine learning have allowed building models on this ever increasing amounts of data. Consequently, devices all the way from heavy assets such as aircraft engines to wearables such as health monitors can all now not only generate massive amounts of data but can draw back on aggregate analytics to "improve" their performance over time. Big data analytics has been identified as a key enabler for the IoT. In this chapter, we discuss various avenues of the IoT where big data analytics either is already making a significant impact or is on the cusp of doing so. We also discuss social implications and areas of concern.Comment: 33 pages. draft of upcoming book chapter in Japkowicz and Stefanowski (eds.) Big Data Analysis: New algorithms for a new society, Springer Series on Studies in Big Data, to appea

Bunching of fluxons by the Cherenkov radiation in Josephson multilayers

A single magnetic fluxon moving at a high velocity in a Josephson multilayer (e.g., high-temperature superconductor such as BSCCO) can emit electromagnetic waves (Cherenkov radiation), which leads to formation of novel stable dynamic states consisting of several bunched fluxons. We find such bunched states in numerical simulation in the simplest cases of two and three coupled junctions. At a given driving current, several different bunched states are stable and move at velocities that are higher than corresponding single-fluxon velocity. These and some of the more complex higher-order bunched states and transitions between them are investigated in detail.Comment: 6 pages + 6 Figures, to be published in Phys. Rev. B on July 1, 200

Evidence for HI replenishment in massive galaxies through gas accretion from the cosmic web

We examine the H i -to-stellar mass ratio (H i fraction) for galaxies near filament backbones within the nearby Universe (d < 181 Mpc). This work uses the 6 degree Field Galaxy Survey (6dFGS) and the Discrete Persistent Structures Extractor (DisPerSE) to define the filamentary structure of the local cosmic web. H i spectral stacking of H i Parkes All Sky Survey (HIPASS) observations yield the H i fraction for filament galaxies and a field control sample. The H i fraction is measured for different stellar masses and 5th nearest neighbour projected densities (Σ5) to disentangle what influences cold gas in galaxies. For galaxies with stellar masses log(M⋆) ≤ 11 M⊙ in projected densities 0 ≤ Σ5 < 3 galaxies Mpc−2, all H i fractions of galaxies near filaments are statistically indistinguishable from the control sample. Galaxies with stellar masses log(M⋆) ≥ 11 M⊙ have a systematically higher H i fraction near filaments than the control sample. The greatest difference is 0.75 dex, which is 5.5σ difference at mean projected densities of 1.45 galaxies Mpc−2. We suggest that this is evidence for massive galaxies accreting cold gas from the intra-filament medium which can replenish some H i gas. This supports cold mode accretion where filament galaxies with a large gravitational potential can draw gas from the large scale structure