The magneto-optical Faraday effect in spin liquid candidates

We propose an experiment to use the magneto-optical Faraday effect to probe the dynamic Hall conductivity of spin liquid candidates. Theory predicts that an external magnetic field will generate an internal gauge field. If the source of conductivity is in spinons with a Fermi surface, a finite Faraday rotation angle is expected. We predict the angle to scale as the square of the frequency rather than display the standard cyclotron resonance pattern. Furthermore, the Faraday effect should be able to distinguish the ground state of the spin liquid, as we predict no rotation for massless Dirac spinons. We give a semiquantitative estimate for the magnitude of the effect and find that it should be experimentally feasible to detect in both $\kappa$-(ET)$_2$Cu$_2$(CN)$_3$ and, if the spinons form a Fermi surface, Herbertsmithite. We also comment on the magneto-optical Kerr effect and show that the imaginary part of the Kerr angle may be measurable.Comment: 5 pages, 1 figur

Experiment Design for Complex VTOL Aircraft with Distributed Propulsion and Tilt Wing

Selected experimental results from a wind tunnel study of a subscale VTOL concept with distributed propulsion and tilt lifting surfaces are presented. The vehicle complexity and automated test facility were ideal for use with a randomized designed experiment. Design of Experiments and Response Surface Methods were invoked to produce run efficient, statistically rigorous regression models with minimized prediction error. Static tests were conducted at the NASA Langley 12-Foot Low-Speed Tunnel to model all six aerodynamic coefficients over a large flight envelope. This work supports investigations at NASA Langley in developing advanced configurations, simulations, and advanced control systems

THE EFFECT OF CERVICAL SPINE ISOMETRIC CONTRACT-RELAX TECHNIQUE ON HAMSTRING EXTENSIBILITY

Objectives: To re-investigate the effect of a cervical isometric contract-relax technique on hamstring extensibility and examine the duration of any treatment effect

Transport phenomenology for a holon-spinon fluid

We propose that the normal-state transport in the cuprate superconductors can be understood in terms of a two-fluid model of spinons and holons. In our scenario, the resistivity is determined by the properties of the holons while magnetotransport involves the recombination of holons and spinons to form physical electrons. Our model implies that the Hall transport time is a measure of the electron lifetime, which is shorter than the longitudinal transport time. This agrees with our analysis of the normal-state data. We predict a strong increase in linewidth with increasing temperature in photoemission. Our model also suggests that the AC Hall effect is controlled by the transport time.Comment: 4 pages, 1 postscript figure. Uses RevTeX, epsf, multico

Determining the Optimal Fee-Technical Proposal Combination in Two Envelope Fee Bidding

Two envelope fee bidding is a mechanism used by construction clients to allocate commissionsto willing consultants such as architects, engineers and surveyors. In two envelopefee bidding the client scores the competing consultants’ fees and technical proposals.The fee and technical proposal scores are weighted and aggregated and the consultantobtaining the highest aggregated score normally wins the commission. The consultant’sobjective in bidding, therefore, is to obtain the highest aggregated score possible since thismaximizes the chance of winning the commission. Given that fee and technical proposalscores are to some extent correlated, consultants can submit any one from a number ofdifferent fee—technical proposal combinations, ranging from a low fee—low scored technicalproposal combination to a high fee—high scored technical proposal combination.Only one possible combination will result in the highest aggregated score. Drew et al(2002b) offered consultants a model to determine this optimum fee-technical proposalcombination for any given commission. This paper tests the proposed model using datacollected from a leading Hong Kong consultant. The analysis, based on 51 bidding attempts,indicates that had the consultant adopted the proposed optimization model, theoverall average improvement on the consultant’s original total scores was 7.07%. The optimumstrategy was to aim for an absolute low fee—low scored technical proposal on 20occasions, absolute high scored technical proposal—high fee on 21 occasions and somewherebetween these two extremes on the remaining 10 occasions. The extent to whichfees scores and technical scores vary relative to each other has an important influence onthe optimum fee—technical proposal combination. However, the client’s change from a70/30 to a 50/50 predetermined weighting appears to have little effect on the consultant’soptimum bidding strategy

The Past in the Present: How Innovative History-making Shapes Our Many Mountains

Kathryn Newfont, Professor of History at Mars Hill University, will reflect on how collaborations such as the Madison County “Forever Free” project extension can shape our understanding not only of the Appalachian region’s complex past, but also of its multi-faceted present. Drew Reisinger’s efforts to unearth the history of chattel slavery in the public records under his care set a new standard for the nation. From the beginning Reisinger emphasized the importance of this historical work to the present-day citizens of Buncombe County, who elect the Register of Deeds. Now, in another Appalachian innovation, educators and students with Mars Hill University’s Public History Program have extended this remarkable effort into neighboring Madison County. Newfont will reflect on the potential this sort of work has for transforming our understanding of slavery in the southern mountain region and beyond. She will consider ways this collaboration and others like it can not only extend our grasp of the Appalachian region’s “Many Mountains” past, but also shapes our understandings of its complex “Many Mountains” present

An Analysis of ALMA Deep Fields and the Perceived Dearth of High-z Galaxies

Deep, pencil-beam surveys from ALMA at 1.1-1.3mm have uncovered an apparent absence of high-redshift dusty galaxies, with existing redshift distributions peaking around $z\sim1.5-2.5$. This has led to a perceived dearth of dusty systems at $z>4$, and the conclusion, according to some models, that the early Universe was relatively dust-poor. In this paper, we extend the backward evolution galaxy model described by Casey et al. (2018) to the ALMA regime (in depth and area) and determine that the measured number counts and redshift distributions from ALMA deep field surveys are fully consistent with constraints of the infrared luminosity function (IRLF) at $z<2.5$ determined by single-dish submillimeter and millimeter surveys conducted on much larger angular scales ($\sim1-10$deg$^{2}$). We find that measured 1.1-1.3mm number counts are most constraining for the measurement of the faint-end slope of the IRLF at $z4$. Recent studies have suggested that UV-selected galaxies at $z>4$ may be particularly dust-poor, but we find their millimeter-wave emission cannot rule out consistency with the Calzetti dust attenuation law even by assuming relatively typical, cold-dust ($T_{\rm dust}\approx30\,$K) SEDs. Our models suggest that the design of ALMA deep fields requires substantial revision to constrain the prevalence of $z>4$ early Universe obscured starbursts. The most promising avenue for detection and characterization of such early dusty galaxies will come from future ALMA 2mm blank field surveys covering a few hundred arcmin$^{2}$ and the combination of existing and future dual-purpose 3mm datasets.Comment: 21 pages, 12 figures, accepted for publication in Ap

An Evaluation Testbed for Alternative Wind Turbine Blade Tip Designs

The majority of present-day horizontal axis wind turbine blade tips are simple designs based on historical trends. There is, however, some evidence that varying the design of the tip can result in significant changes in performance characteristics such as power output, noise, and structural loading. Very few studies have tested this idea on an actual rotating blade and there is much to be investigated. Thus, a project was devised to examine experimentally the effect of various tip designs on an operational rotating wind turbine rotor. A tapered, twisted blade 1.6 m in length was custom designed for use in the UW Wind Energy Research Facility using the blade element momentum (BEM) method. A coupling mechanism was designed such that the outer 10% of each blade could be exchanged to evaluate the effect of different tip designs. A set of three blades was fabricated out of fibre-reinforced plastic, while the tips were machined out of maple wood on a CNC milling machine. The blade was evaluated with a standard rectangular tip to establish baseline performance against which to compare the alternative tip configurations. The three-bladed rotor was tested at shaft speeds from 100 rpm to 240 rpm in wind speeds up to the facility maximum of 11.1 m/s. The rotor was found to have a maximum power coefficient of 0.42 at a tip speed ratio of 5.3 and a 1.45 kW rated power at a wind speed of 11 m/s. The performance was compared to predictions made using the BEM method with airfoil data generated using a modified Viterna method and the Aerodas method. While the Aerodas data was capable of predicting the power fairly accurately from 5 m/s to 10 m/s, the modified Viterna method predicted the entire curve much more accurately. Two winglet designs were also tested. The first (called Maniaci) was designed by David Maniaci of Pennsylvania State University and the other (called Gertz) was designed by the author. Both winglets were found to augment the power by roughly 5% at wind speeds between 6.5 m/s and 9.5 m/s, while performance was decreased above and below this speed range. It was calculated that the annual energy production could be increased using the Maniaci and Gertz winglets by 2.3% and 3%, respectively. Considering the preliminary nature of the study the results are encouraging and it is likely that more optimal winglet designs could be designed and evaluated using the same method. More generally, this study proved that the blades with interchangeable tips are capable of being used as an evaluation testbed for alternative wind turbine blade tip designs

The Persistence of Advertising Culture: Commerce and Consumers in Multi-Ethnic Galicia, 1911-1921

Despite tremendous change and instability during the second decade of the twentieth century due to modernization, war, and political reconfiguration, some elements of everyday life in Cracow and Lemberg maintained a remarkable measure of superficial resilience. This study explores the resilience of newspaper advertising culture despite the violence and turmoil experienced during and after the First World War. It seeks to explain the ways in which advertising proved adaptable and the ways that it subtly, but significantly, changed. Both newspaper culture and advertising as a mode of social communication survived the war years and the unstable years in the early interwar period. This is a testament to their integral nature in the character of the modern cities of Cracow and Lemberg. The system of newspaper advertising had been in place for over a decade before the war broke out; and the level of its usage in the immediate years preceding the war is evidence of its familiarity, utility, and acceptance among the populations of Cracow and Lemberg. Though some areas of modern life suffered lapses that seemed to arrest the effects and benefits of modernization, newspaper advertising survived the war because it was an established part of urban culture prior to this period, and because it was able to adapt to the needs of advertisers during times of conflict. Further, as a reflection of the urban culture in Cracow and Lemberg, advertising as a mode of social communication serves as a lens to highlight changes in class and gender dynamics during the period from 1911 to 1921