On the surface drift of the Southern Ocean

Drift rates of the sea surface have been calculated for the South Atlantic and South Indian Ocean sectors of the Southern Ocean using drift cards and FGGE buoys. Drift patterns and drift rates, based on results from 40,000 plastic drift cards placed from 1978 to 1981, indicate significant equatorward surface exchange between the Southern Ocean and subtropical ocean gyres. Card drift rates increase with latitude up to the 40-45S zone. Average zonal drift rates lie between 10.3 cm/s and 16.4 cm/s. Zonally averaged drift rates of FGGE buoys are also at a maximum between 40 and 45S but are 15% higher; lowest rates are 12.2 cm/s. Significant differences in the drift rates between sectors of the same zone reflect the influence of bottom topography

Direct Numerical Simulation Of Hypersonic Turbulent Boundary Layers. Part 2. Effect Of Wall Temperature

In this paper, we perform direct numerical simulation (DNS) of turbulent boundary layers at Mach 5 with the ratio of wall-to-edge temperature T w/T ℘ from 1.0 to 5.4 (Cases M5T1 to M5T5). The influence of wall cooling on Morkovin\u27s scaling, Walz\u27s equation, the standard and modified strong Reynolds analogies, turbulent kinetic energy budgets, compressibility effects and near-wall coherent structures is assessed. We find that many of the scaling relations used to express adiabatic compressible boundary-layer statistics in terms of incompressible boundary layers also hold for non-adiabatic cases. Compressibility effects are enhanced by wall cooling but remain insignificant, and the turbulence dissipation remains primarily solenoidal. Moreover, the variation of near-wall streaks, iso-surface of the swirl strength and hairpin packets with wall temperature demonstrates that cooling the wall increases the coherency of turbulent structures. We present the mechanism by which wall cooling enhances the coherence of turbulence structures, and we provide an explanation of why this mechanism does not represent an exception to the weakly compressible hypothesis. © 2010 Cambridge University Press

A Musical instrument in MEMS

In this work we describe a MEMS instrument that resonates at audible frequencies, and with which music can be made. The sounds are generated by mechanical resonators and capacitive displacement sensors. Damping by air scales unfavourably for generating audible frequencies with small devices. Therefore a vacuum of 1.5 mbar is used to increase the quality factor and consequently the duration of the sounds to around 0.25 s. The instrument will be demonstrated during the MME 2010 conference opening, in a musical composition especially made for the occasion

Analyzing Four-Year Public University and Two-Year College Graduation Rates

This paper examines the graduation rates between 2000 and 2015 of United States colleges and universities at the national, state, and institutional levels. This research focuses on two-year and four-year programs. Rates are investigated longitudinally along with variables that distinguish between public/private institutions, percentages of full-time and part-time enrollments, a variety of completion times, and levels of academic achievement at entry that include SAT scores and high school GPAs. The paper uses a logistic growth function that has been used by other researchers to model four-, five-, and six-year graduation rates of individuals and selected cohort groups; graduation rate trajectories for students of differing academic achievement backgrounds are projected into the future to demonstrate maximum graduation rates expected for entering cohorts. Included is the analysis of national, state, and institutional graduation-rate results in four-year institutions of the 50 states; examples from 14 public colleges and universities in Indiana and several surrounding states are also considered. In addition to fitting their graduation rates to the logistic function and extracting associated growth variables, we use percentages of part-time students to predict two- and four-year graduation rates at the national, state, and institutional levels in the 50 states. The analysis examined the graduation rates between 2000 and 2015 of United States colleges and universities and showed no correlation between a state’s two-year and four-year cohort graduation rates; verified an inverse mathematical relationship between graduation rates and percentage of part-time students; confirmed that for median SAT scores of 800 or lower one expects very low on-time graduation rates

Edwardsiella ictaluri encodes an acid-activated urease that is required for intracellular replication in channel catfish (Ictalurus punctatus) macrophages

Genomic analysis indicated that Edwardsiella ictaluri encodes a putative urease pathogenicity island containing the products of nine open reading frames, including urea and ammonium transporters. In vitro studies with wild-type E. ictaluri and a ureG::kan urease mutant strain indicated that E. ictaluri is significantly tolerant of acid conditions (pH 3.0) but that urease activity is not required for acid tolerance. Growth studies demonstrated that E. ictaluri is unable to grow at pH 5 in the absence of urea but is able to elevate the environmental pH from pH 5 to pH 7 and grow when exogenous urea is available. Substantial production of ammonia was observed for wild-type E. ictaluri in vitro in the presence of urea at low pH, and optimal activity occurred at pH 2 to 3. No ammonia production was detected for the urease mutant. Proteomic analysis with two-dimensional gel electrophoresis indicated that urease proteins are expressed at both pH 5 and pH 7, although urease activity is detectable only at pH 5. Urease was not required for initial invasion of catfish but was required for subsequent proliferation and virulence. Urease was not required for initial uptake or survival in head kidney-derived macrophages but was required for intracellular replication. Intracellular replication of wild-type E. ictaluri was significantly enhanced when urea was present, indicating that urease plays an important role in intracellular survival and replication, possibly through neutralization of the acidic environment of the phagosome. Copyright © 2009, American Society for Microbiology. All Rights Reserved

Fabrication and Characterization of Topological Insulator Bi2_2Se3_3 Nanocrystals

In the recently discovered class of materials known as topological insulators, the presence of strong spin-orbit coupling causes certain topological invariants in the bulk to differ from their values in vacuum. The sudden change of invariants at the interface results in metallic, time reversal invariant surface states whose properties are useful for applications in spintronics and quantum computation. However, a key challenge is to fabricate these materials on the nanoscale appropriate for devices and probing the surface. To this end we have produced 2 nm thick nanocrystals of the topological insulator Bi$_2$Se$_3$ via mechanical exfoliation. For crystals thinner than 10 nm we observe the emergence of an additional mode in the Raman spectrum. The emergent mode intensity together with the other results presented here provide a recipe for production and thickness characterization of Bi$_2$Se$_3$ nanocrystals.Comment: 4 pages, 3 figures (accepted for publication in Applied Physics Letters

Moral Attributes In A Dictator Game

This paper investigates whether or not the moral factors captured in an emotional intelligence assessment matter in the economic decisions made by subjects in a dictator game.  We find a statistically significant relationship between the amount of the dictator’s contribution and a few of the factors of the Intrapersonal Dimension of the EQ-i. We also find a significant relationship between dictator contributions and an adjusted EQ-i score, measures of independence, know-my-own and empathy. Our results may be relevant to researchers interested in understanding the preference set of economic decision-makers.  Moreover, for those interested in refining experimental design protocols, we show the EQ-i to be a useful resource to control for a few of the moral attributes Levitt et al. (2006) suggest are so very important in understanding laboratory and field experiments.

Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements

Protecting quantum information from errors is essential for large-scale quantum computation. Quantum error correction (QEC) encodes information in entangled states of many qubits, and performs parity measurements to identify errors without destroying the encoded information. However, traditional QEC cannot handle leakage from the qubit computational space. Leakage affects leading experimental platforms, based on trapped ions and superconducting circuits, which use effective qubits within many-level physical systems. We investigate how two-transmon entangled states evolve under repeated parity measurements, and demonstrate the use of hidden Markov models to detect leakage using only the record of parity measurement outcomes required for QEC. We show the stabilization of Bell states over up to 26 parity measurements by mitigating leakage using postselection, and correcting qubit errors using Pauli-frame transformations. Our leakage identification method is computationally efficient and thus compatible with real-time leakage tracking and correction in larger quantum processors.Comment: 22 pages, 15 figure