Klein tunneling and cone transport in AA-stacked bilayer graphene

We investigate the quantum tunneling of electrons in an AA-stacked bilayer graphene (BLG) $n$-$p$ junction and $n$-$p$-$n$ junction. We show that Klein tunneling of an electron can occur in this system. The quasiparticles are not only chiral but are additionally described by a `cone index'. Due to the orthogonality of states with different cone indexes, electron transport across a potential barrier must strictly conserve the cone index and this leads to the protected cone transport which is unique in AA-stacked BLG. Together with the negative refraction of electrons, electrons residing in different cones can be spatially separated according to their cone index when transmitted across an $n$-$p$ junction. This suggests the possibility of `cone-tronic' devices based on AA-stacked BLG. Finally, we calculate the junction conductance of the system.Comment: 11 pages, 7 figures; corrected typo, final submitted versio

Conesus Lake Fish Stock Assessments 2001-2009

Warm water fisheries assessments using standard gangs of gill nets were conducted in Conesus Lake in September of 2001, 2004, and 2009. The purpose of the surveys was to assess the fish community; the contribution of stocked fingerlings to the walleye (Sander vitreus) population; estimate population characteristics of walleye, smallmouth bass (Micropterus dolomieui), and northern pike (Esox lucius); compare fish community structure to previous surveys; and guide the development of appropriate management recommendations. From the 1990’s to the 2000’s, species dominance shifted from walleye to sunfish (Lepomis, sp.), and yellow perch (Perca flavescens) went from being a major component of the fish community in 1991 to a minor component in 1997, to nearly absent in 2004. Brown bullhead (Ameirus nebulosus) became an increasingly larger component of the fish community in the 2000’s. The walleye population during the 2000’s had an abundance of larger, older fish in excellent condition. Despite extensive migratory spawning runs in the inlet streams that could be producing fry that potentially recruit to adults, the walleye population is mainly sustained by stocked fingerlings. While they are growing slower than in the 1990’s, survival and recruitment of the stocked fingerlings remains good. Slower growth and lower condition could be a sign that the alewife population in Conesus Lake is declining, but no definitive statement regarding the alewife population can be made until further hydroacoustic surveys of the forage community are conducted. Because of discrepancies of scale ages among readers, walleye age and growth analyses for these surveys should be viewed cautiously, and otoliths should be used to age walleye in future surveys. The fishing quality for Conesus Lake walleyes should remain very good for several years. The smallmouth bass population by 2009 had an abundance of larger, older fish in fair condition. The 2007 and 2006 year classes appear to be strong, but individual fish of these year classes may grow slowly and be in less than desirable condition. The fishing quality for Conesus Lake smallmouths should remain good for several years as the fish from these year classes mature and grow. Northern pike appear to be moderately abundant. The recent maintenance of appropriate lake water levels during early spring have provided adequate flooding of constructed marshes in the Conesus Inlet Wildlife Management Area. This appears to have resulted in successful spawning, fry production, survival, and recruitment of northern pike. Adult pike, while fast growing, are in below average condition in Conesus Lake. The yellow perch decline in abundance following a late 1970’s alewife (Alosa pseudoharengus) invasion continued during the 1991- 1997 period and remained at this low level from 2001 to 2009. Alewife gill net CPUE varied greatly from 1985 to 2001 and remained at a consistent low level since 2001. While relatively large, yellow perch are in poor condition and alewives are smaller than average and in poor condition. Rock bass (Ambloplites rupestris) and bluegill (Lepomis macrochirus) relative abundance doubled from 2001 to 2009, while pumpkinseed (Lepomis gibbosus) abundance showed little change. Survival and growth appears to be consistent for all three species. Growth was above average for all three species, but condition was poor for rock bass and moderately poor for pumpkinseed and bluegill. Rock bass size structure was poor and few preferred sized 2 pumpkinseeds and bluegills were sampled. Size quality in bluegills declined from 1991-1997 levels. It is recommended that all current management actions be continued, 50 day walleye fingerlings be stocked annually over five years, the success of stocked 50 day walleye fingerlings be evaluated, and new objectives be developed in a revised Conesus Lake fisheries management plan

Post COVID 19 and food pathways to sustainable transformation

International audienc

Testing a global city hypothesis : an assessment of polarization across US cities

Social polarization is perhaps most evident within the world's large cities where we can easily observe stark contrasts between wealth and poverty. A world city theoretical perspective has emerged that associates large cities importance in a global network of cities to the degree of internal polarization within these cities. The research reported here locates 57 large US cities within this world city hierarchy and then empirically examines the hypothesized positive association between global centrality and social polarization using a multivariate, cross-city analysis. The findings are mixed, with some evidence that global centrality increases income polarization, but only in the context of higher levels of immigration. There is no evidence that a city's centrality affects occupational polarization. We conclude by suggesting implications for the world city literature and future research

Estimation of the urban heat island for UK climate change projections

Copyright © 2010 by SAGE PublicationsCities are known to exert a significant influence on their local climate, and are generally warmer than their surroundings. However, climate models generally do not include a representation of urban areas, and so climate projections from models are likely to underestimate temperatures in urban areas. A simple methodology has been developed to calculate the urban heat island (UHI) from a set of gridded temperature data; the UHI may then be added to climate model projections and weather data files. This methodology allows the UHI to be calculated on a monthly basis and downscaled to hourly for addition to weather generator data. The UHI intensities produced are found to be consistent with observed data.Practical application: There is overwhelming consensus amongst the scientific community that the Earth’s climate is warming. In addition to the effects of climate change the urban heat island (UHI) effect can increase air temperatures significantly in urban areas above those of the rural areas around them. The proposed methodology for calculating the UHI from a set of gridded temperature data allows the UHI to be added to climate model projections such as UKCP09 or HadRM3 and weather data files. The methodology also allows for the temporal downscaling of the UHI from monthly values to hourly data for use in building thermal simulation software

Nonlinear optical conductivity of bilayer graphene with Rashba spin-orbit interaction in the terahertz regime

The effect of Rashba spin-orbit coupling on the nonlinear optical conductivity in a bilayer graphene is investigated. We demonstrate the very different role played by the Rashba term and interlayer hopping; in some cases, the two roles can be quite opposite. It is found that the Rashba term can either enhance or suppress the nonlinear effect in a bilayer graphene, depending on the strength of the interlayer hopping. For a weak interlayer hopping, the Rashba term can significantly enhance the nonlinear effect. An analytical result was derived, showing the interplay of the Rashba effect and the interlayer hopping effect

The Dinosauria: Baraminological and Multivariate Patterns

The Dinosauria pose both interesting and challenging questions for creationist systematists. One question is whether new dinosaur discoveries are closing morphospatial gaps between dinosaurian groups, revealing continuous morphological fossil series, such as between coelurosaurians and avialans. Questions such as these underscore the importance of systematics for resolving correct group memberships, including tools for visualizing morphospatial relationships. Baraminic distance correlation (BDC), three-dimensional multidimensional scaling (MDS), and a new method to baraminic studies – principal component analysis (PCA) – were applied to 18 character matrices from 2004. The data included saurischian and ornithischian dinosaur groups including (1) “basal” Saurischia, (2) Ceratosauria (including Coelophysidae), (3) “basal” Tetanurae, (4) Tyrannosauroidea, (5) “Prosauropoda”, (6) Sauropoda, (7) Maniraptoriformes, (8) Therizinosauroidea, and (9) Oviraptorosauria. The ornithischians included (10) “basal” Thyreophora, (11) Stegosauria, (12) Ankylosauria, (13) “basal” Ornithopoda, (14) “basal” Iguanodontia, (15) Hadrosauridae, (16) Pachycephalosauria, (17) “basal” Ceratopsia, and (18) Ceratopsidae. BDC and MDS revealed several potential holobaramins and apobaramins, and PCA identified some divisions not recognized by the traditional methods, but since the datasets are 14 years old, many important taxa are missing. As a result, we performed PCA on 19 newer datasets (from 2009 to 2018) and compared the results, which revealed a substantially clearer picture since only 2004. Dinosaur group ordinations commonly occur within morphospatial clusters or linear series. Holobaramins were revealed mainly as closely-spaced morphospatial series of taxa. Some series were additionally stratomorphic. Assuming holobaramins are discontinuity-bounded morphospatial series of taxa, we estimate 27 potential holobaramins within the newer data. PCA revealed that bird-dinosaur morphospatial relationships vary by dataset. Paravians likely contain two branching morphoseries, connected at the base by dromaeosaurs and avialans. The two morphoseries are functional/ecological, rather than evolutionary. Multivariate analysis offers the potential to improve our understanding of baramins and discontinuity, and provide a new perspective on questions in creation systematics such as bird-dinosaur relationships

Topologically guaranteed enhancement of nonlinear optical conductivity of graphene in the presence of spin-orbit coupling

We demonstrate that a topological invariant term in graphene (e.g., spin-orbit coupling or interlayer coupling induced trigonal warping) can lead to a strong nonlinear optical response. We present a full quantum-mechanical analysis of the third-order nonlinear optical conductivity of the monolayer graphene with a finite Rashba spin-orbit coupling. For energy of the incident photon below the maximum height of the trigonal warping and the Rashba coupling strength exceeding a critical value the nonlinear conductance is enhanced dramatically in comparison with that in the absence of the topological term. Due to the trigonal warping effect and the topologically inequivalent change of the geometry of the energy band, the strong nonlinear effect persists, as long as the incident photon energy is limited below the energy maximum defined by the spin-orbit coupling

Effect of Ethanol on Triacylglycerol Synthesis in Chlorella Species Utilizing a Novel Fluorescence-Based Assay

In this study, I set out to develop a novel method of assaying acyl-CoA: diacylglycerol acyltransferase (DGAT) activity employing a fluorescently labeled substrate, and then using that protocol to determine the effects of ethanol-induced stress on DGAT activity in Chlorella species. Microsomes from Chlorella sp. were used to construct protein and time curves to characterize the method in microalgae. Microsomes from Rattus liver were used to construct a substrate concentration curve and a Lineweaver-Burk plot to characterize the method in mammalian tissue. Optimal reaction conditions were determined to be 10 ?g microsomal protein with 20 min incubation. The mammalian microsomes provided a Km of 6.26 ?M substrate concentration and a Vmax of 0.211 pmol product x min-1 x ?g protein-1. This method represents the first fluorescence based DGAT assay. Chlorella sp. cultures were exposed to 0.33%, 0.66%, and 1.00% ethanol concentrations for 3 hr, and the DGAT activity assayed under optimal conditions. Increases in DGAT activity were observed in all cultures exposed to ethanol with a maximum seen at 0.66% concentration. These results have implications towards improving biodiesel production in mass algal cultures