Hot Spots on the Fermi Surface of Bi2212: Stripes versus Superstructure

In a recent paper Saini et al. have reported evidence for a pseudogap around (pi,0) at room temperature in the optimally doped superconductor Bi2212. This result is in contradiction with previous ARPES measurements. Furthermore they observed at certain points on the Fermi surface hot spots of high spectral intensity which they relate to the existence of stripes in the CuO planes. They also claim to have identified a new electronic band along Gamma-M1 whose one dimensional character provides further evidence for stripes. We demonstrate in this Comment that all the measured features can be simply understood by correctly considering the superstructure (umklapp) and shadow bands which occur in Bi2212.Comment: 1 page, revtex, 1 encapsulated postscript figure (color

The Schwaigerian driver transfer technique and the Thevenin's and the Norton's theorem Final report

Graphical technique for analyzing series-parallel networks by rectangular diagrams in solving power distribution problem

BSE and the Dynamics of Beef Consumption: Influences of Habit and Trust

This study relates habit persistence and trust to recurring food safety incidents in the context of a series of three BSE incidents in Canada. We examined the dynamics of monthly beef expenditure shares of a sample of Canadian households for monthly time periods during year 2002 through 2005 using micro level panel data which followed meat expenditures by Canadian households before and after the first three BSE cases which were discovered in 2003 and 2005. Our results suggest that households’ reactions to the first three BSE events followed a similar general pattern: households reduced beef purchase expenditures following the discovery of BSE but these expenditures subsequently recovered, suggesting that concern diminished over time. Following the first BSE event, we identified an immediate negative impact on beef expenditures. However, in the case of the second and third BSE events, this negative impact was not evident until two months after these BSE announcements. In each of the three cases, the negative impact of BSE on beef purchase expenditures was limited to no more than four months. Assessment of how habit persistence affected beef expenditures indicates that this influence limited households reductions of beef purchases following the BSE events, but the effects of habit diminished subsequent to the initial event. Regarding the role of trust in shaping households’ reactions to BSE, we found that households’ respondents whose answers to standardized questions suggest that they are not “trusting” individuals were more sensitive to the food risks identified by the BSE events.BSE, habit, and trust, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety,

Influence of generalized trust on Canadian consumers’ reactions to the perceived food risk of three recurring BSE cases

Interest in the influence of trust on consumers’ responses to food risk perceptions associated with Canadian instances of BSE motivates this study, in which Canadian households’ expenditures on fresh meat are assessed in the context of the first three recurring risk events in which bovine spongiform encephalopathy (BSE) was found to have affected Canadian cows. Engel Curve analysis focusing on the dynamics of the monthly meat expenditure shares for a selected sample of 437 Canadian households for 2002 through 2005 is applied based on data on household expenditures for meat purchased by a national sample of Canadian households from the Nielsen Homescan® Canadian panel, supplemented by survey responses on BSE risk perceptions and measures of trust. Two sets of models are estimated: Engel curves in differences with instruments in levels and Engel curves in levels with instruments in differences. It is found that habit persistence limited households’ reductions of beef purchases following the first BSE event and that that trust limited households’ reduction in beef expenditure shares following the subsequent two BSE cases. Significant seasonal effects and a significant negative influence on beef expenditure shares are also found, consistent with the trend of declining consumption of beef in Canada since the late 1990s.BSE, Generalized Method of Moments (GMM), trust, Consumer/Household Economics, D12, C29,

THE INFLUENCE OF ATTRIBUTE CUTOFFS ON CONSUMERS’ CHOICES OF A FUNCTIONAL FOOD

This study investigates evidence of non-compensatory preferences by incorporating attribute cutoffs into the modeling of consumer choices in the context of food with health-related attributes (omega-3 content) that may be associated with fortification or may result from genetic modification (GM). Data for this study were collected through a nation-wide internet-based survey drawn from a representative panel of Canadian households maintained by a major North American marketing firm. In addition to querying respondents on their perceptions and attitudes regarding food and health, choices of canola oils are elicited using a stated choice experiment in which product alternatives are identified based on attributes of price, country of origin, omega-3 content and GM/non-GM derivation. Consumers’ choices for functional canola oil products are examined in three steps. Initially, a conditional logit (CL) model is estimated assuming that no cutoffs apply in decisions on canola oil choices. Respondent’s self-reported cutoffs are then incorporated into the CL model and a random parameters logit (RPL) model, applying a utility model which penalizes rather than eliminates a desired alternative when a cutoff violation occurs. In the third step, the problem of endogeneity associated with attribute cutoffs is examined by linking respondents’ self-reported cutoffs to their demographic characteristics. Results from estimations of models with/without cutoffs show that consumers value omega-3 content in canola oils but dislike GM-derived ingredients in canola oil products. These Canadian respondents prefer canola oils produced in Canada to those produced in the United States. Regarding attribute cutoffs, it is found that consumers suffer a utility loss when violating their self-reported attribute cutoffs. Comparisons between models with/without attribute cutoffs suggest that incorporating cutoffs into the compensatory utility model significantly improves the model fit. Cutoff endogeneity is examined by predicting cutoffs based on respondents’ demographic characteristics. Using predicted cutoffs as instruments for self-reported cutoffs, this study provides some evidence that self-reported cutoffs may be endogenous and that researchers should consider using approaches that account for the potential endogeneity.decision strategy, attribute cutoff, functional food, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, Health Economics and Policy, C25, C93, D1,

Superconducting gap symmetry of Ba0.6K0.4Fe2As2 studied by angle-resolved photoemission spectroscopy

We have performed high-resolution angle-resolved photoemission spectroscopy on the optimally-doped Ba$_{0.6}$K$_{0.4}$Fe$_2$As$_2$ compound and determined the accurate momentum dependence of the superconducting (SC) gap in four Fermi-surface sheets including a newly discovered outer electron pocket at the M point. The SC gap on this pocket is nearly isotropic and its magnitude is comparable ($\Delta$ $\sim$ 11 meV) to that of the inner electron and hole pockets ($\sim$12 meV), although it is substantially larger than that of the outer hole pocket ($\sim$6 meV). The Fermi-surface dependence of the SC gap value is basically consistent with $\Delta$($k$) = $\Delta$$_0$cos$k_x$cos$k_y$ formula expected for the extended s-wave symmetry. The observed finite deviation from the simple formula suggests the importance of multi-orbital effects.Comment: 4 pages, 3 figures, 1 tabl

Holistic engineering design : a combined synchronous and asynchronous approach

To aid the creation and through-life support of large, complex engineering products, organizations are placing a greater emphasis on constructing complete and accurate records of design activities. Current documentary approaches are not sufficient to capture activities and decisions in their entirety and can lead to organizations revisiting and in some cases reworking design decisions in order to understand previous design episodes. Design activities are undertaken in a variety of modes; many of which are dichotomous, and thus each require separate documentary mechanisms to capture information in an efficient manner. It is possible to identify the modes of learning and transaction to describe whether an activity is aimed at increasing a level of understanding or whether it involves manipulating information to achieve a tangible task. The dichotomy of interest in this paper is that of synchronous and asynchronous working, where engineers may work alternately as part of a group or as individuals and where different forms of record are necessary to adequately capture the processes and rationale employed in each mode. This paper introduces complimentary approaches to achieving richer representations of design activities performed synchronously and asynchronously, and through the undertaking of a design based case study, highlights the benefit of each approach. The resulting records serve to provide a more complete depiction of activities undertaken, and provide positive direction for future co-development of the approaches

Three realizations of quantum affine algebra Uq(A2(2))U_q(A_2^{(2)})

In this article we establish explicit isomorphisms between three realizations of quantum twisted affine algebra $U_q(A_2^{(2)})$: the Drinfeld ("current") realization, the Chevalley realization and the so-called $RLL$ realization, investigated by Faddeev, Reshetikhin and Takhtajan.Comment: 15 page

Modeling Magnetic Field Structure of a Solar Active Region Corona using Nonlinear Force-Free Fields in Spherical Geometry

We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all boundaries, to cases where noisy vector data are provided on only the lower boundary (approximating the solar problem). Analytical tests also show that the NLFFF code in the spherical geometry performs better than that in the Cartesian one when the field of view of the bottom boundary is large, say, $20^\circ \times 20^\circ$. Additionally, We apply the NLFFF model to an active region observed by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory (SDO) both before and after an M8.7 flare. For each observation time, we initialize the models using potential field source surface (PFSS) extrapolations based on either a synoptic chart or a flux-dispersal model, and compare the resulting NLFFF models. The results show that NLFFF extrapolations using the flux-dispersal model as the boundary condition have slightly lower, therefore better, force-free and divergence-free metrics, and contain larger free magnetic energy. By comparing the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the Atmospheric Imaging Assembly (AIA) on board SDO, we find that the NLFFF performs better than the PFSS not only for the core field of the flare productive region, but also for large EUV loops higher than 50 Mm.Comment: 34 pages, 8 figures, accepted for publication in Ap