Normal all pseudo-Anosov subgroups of mapping class groups

We construct the first known examples of nontrivial, normal, all pseudo-Anosov subgroups of mapping class groups of surfaces. Specifically, we construct such subgroups for the closed genus two surface and for the sphere with five or more punctures. Using the branched covering of the genus two surface over the sphere and results of Birman and Hilden, we prove that a reducible mapping class of the genus two surface projects to a reducible mapping class on the sphere with six punctures. The construction introduces "Brunnian" mapping classes of the sphere, which are analogous to Brunnian links.Comment: Published in Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol4/paper10.abs.htm

A Stackelberg Analysis of the Potential for Cooperation in Straddling Stock Fisheries

To ensure the long-term conservation and sustainable use of straddling fish stocks, the 1995 United Nations Fish Stock Agreement calls for the establishment of regional fisheries management organizations to manage them. This article studies the potential for cooperation in straddling stock fisheries when the cooperative coalition of countries acts as a Stackelberg leader against the remaining singleton countries. Within the Stackelberg fishing game with several interested parties, the result shows that an increase in the cooperation level leads to an increase not only in the steady-state fish stock, but also in the total rent of the fishery. Further, the outlook for cooperation is better within the Stackelberg game, where the cooperative coalition acts as a leader, than in the Cournot game. At the stable equilibrium of a Stackelberg game, not only is the steady-state fish stock higher, but also the total resource rent, participants’ rent, and non-participants’ rent are higher than those of the Cournot-Nash stable equilibrium. The new-entrant issue is a problem for the conservation of fish stock in the Stackelberg game. Self-financed transfers with commitments of the initial stable coalition will increase the level of cooperation. The theoretical findings are illustrated by a numerical example of how to reach stable full cooperation and used to indicate possible ways forward for the South China Sea fisheries.IUU fishing, non-cooperative game, regional fisheries management organization, straddling stock fisheries, stable coalition, Stackelberg game, South China Sea, Environmental Economics and Policy, Institutional and Behavioral Economics, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies, Research Methods/ Statistical Methods, Q22, Q27, R13, R58,

Relativistic Corrections to the Exclusive Decays of C-even Bottomonia into S-wave Charmonium Pairs

Within the nonrelativistic quantum chromodynamics (NRQCD) factorization formalism, we compute the relativistic corrections to the exclusive decays of bottomonia with even charge conjugation parity into $S$-wave charmonium pairs at leading order in the strong coupling constant. Relativistic corrections are resummed for a class of color-singlet contributions to all orders in the charm-quark velocity $v_c$ in the charmonium rest frame. Almost every process that we consider in this work has negative relativistic corrections ranging from -20 to -35,%. Among the various processes, the relativistic corrections of the next-to-leading order in $v_c$ to the decay rate for $\chi_{b2}\to \eta_c(mS)+\eta_c(nS)$ with $m,$ $n=1$ or 2 are very large. In every case, the resummation of the relativistic corrections enhances the rate in comparison with the next-to-leading-order results. We compare our results with available predictions based on the NRQCD factorization formalism. The NRQCD predictions are significantly smaller than those based on the light-cone formalism by an or two orders of magnitudes.Comment: 20 pages, 1 figure. Typos corrected, published versio

Improving Salmon Population Restoration Efforts in California\u27s Central Valley Region

Historically, the rivers draining into California’s Central Valley Region (CCVR) were abundant with Chinook salmon, migrating in four distinct runs throughout every year, including the Sacramento River winter-run & the Central Valley spring-run. Since the advent of the Central Valley Project in the 1930’s, and its 20 federal high rim dams, these salmon runs have become increasingly threatened. Using a comparative analysis research methodology, this Project critically reviews the existing literature to address the research question: how can current practices of Fish Passage Designs (FPDs) and collection-and-transport operations (CTOs) be improved to mitigate impacts created by dams in CCVR? After a critical examination of the research literature, this Project offers two major recommendations to improve current FPD practices: moving away from the use of Denil fishways, in favor of other designs, and creating and maintain proper water velocity and pressure around and within FPDs. Two minor recommendations, namely requiring tag validation studies and engaging in longer term FPD monitoring, are also offered. The Project offers two major recommendations for improving current CTO implementations: emphasizing reducing induced stress during CTOs, and mitigating copepod Salmincola californiensis infection prevalence among salmon subjected to CTOs. These recommendations are meant to improve current salmon run restorative efforts in CCVR geared towards delisting the runs from their current endangered listings. These recommendations are also congruent with the two scientific principles that are the bedrock of current conservation management efforts, namely creating functioning, diverse, and interconnected habitats, and improving species viability dependent on spatial factors

GIS-based modelling of agrochemical use, distribution and accumulation in the Lower Mekong Delta, Vietnam: A case study of the risk to aquaculture

In recent years, the Mekong delta has been strongly developed both for agriculture and aquaculture. However, there is scope for a negative impact of agriculture on aquaculture in term of production and quality of seafood products. Specifically, the large amount of pesticides imported and used in the Mekong delta not only help agriculture purposes but can also easily enter aquatic systems and affect aquaculture. Pesticides can be transported in the environment by chemo-dynamic procedures and hydrological processes. As a result, pesticides used in agriculture become dispersed and their residues in sediment, water and biota have been detected in the Mekong delta. This study investigated the overall pesticide process including pesticide use, modelling pesticide accumulation and evaluating the potential impact on aquaculture sites for some target aquatic species. The risk of pesticides use in the Mekong delta was addressed in three stages: (1) investigating current pesticide use status in the Mekong delta; (2) modelling pesticide loss and accumulation; (3) classifying pesticide risk areas for aquaculture of target cultured species. A survey of 334 farms covering a total area of ~20,000km2 in the Mekong delta took place between 2008 and 2009. Information on pesticide types and quantities was recorded using questionnaires, and it was found that 96 pesticides in 23 groups were popularly used for agricultural purposes. Dicarboximide, Carbamate and Conazole had the highest use at ~3000, ~2000 and ~2000 g/ha/year respectively. The survey revealed an increase in pesticide use per hectare since previous surveys in the Mekong delta in 1994, 2000, and 2004. However, the highly persistent compounds (WHO classification classes II, III and IV) appeared to have reduced in use. Insecticides previously represented >50% of the total pesticides used, however, the resent survey has shown their use has decreased to ~38%.There was a parallel increase in use of fungicides from previous levels of <30% of total pesticides to more recently ~41%. The combination of pesticide information and geo-location data enabled display and analysis of this data spatially using a Geographic Information System (GIS). A pesticide loss and accumulation model was established through combination of several sub-models including sediment loss and accumulation, direct loss, and water runoff, all of which were implemented and integrated within the GIS environment. MUSLE (Modified Universal Soil Loss Equation) was used to estimate sediment loss and accumulation in the Mekong delta and the Curve Number method (CN Method) was applied to predict water runoff and discharges and flow accumulation. Modelling commenced from the first pesticide application in April, based on 4 day time-steps. All mathematical calculations run within each time step automatically reiterated in the following time step with the new input datasets. The results from fuzzy classification of the pesticide model outcomes were considered in terms of the 96hr lethal concentration (LC50) in order to classify the risk and non-risk areas for catfish and tiger shrimp culture. The sediment loss and accumulation model shows that the highest loss of sediment was in the rainy season, especially in May to October. Vegetables and short term crop areas were found be most strongly eroded. The MUSLE model showed that the highest sediment accumulation was in the hilly areas (~1066.42 tonne/ha/year); lower in riverside areas (~230.39 tonne/ha/year) and lowest in flooded paddy areas (~150.15tonne/ha/year). Abamectin was used as an example throughout this study to estimate pesticide loss and its effects on aquaculture. The results showed that pesticide loss by runoff and sediment loss is less than the loss by half-life degradation (for Abamectin specifically). Accumulation of Abamectin occurred at highest rate in May and October and decreased with time. The spatial models showed that pesticide residues concentrated in the river and riverside areas. In order to evaluate the acute toxicity impacts, three levels of water depth in ponds were modelled as culture depths for catfish and tiger shrimp. The results show that the highest risk areas for catfish occurred in May and October with ~333,000 and ~420,000 ha at a pond depth of 0.5 m; ~136,000 and ~183,000 ha at a pond depth of 1.0 m; and ~10,840 and ~19,000 ha at a pond depth of 1.5 m. Risk areas for catfish mainly concentrated at the riverside and in part of the coastal areas. For tiger shrimp, the risk periods during the year were similar to those found for catfish. The highest risk areas for shrimp were ~648,000 and ~771,000 ha at 0.5 m pond depth; ~346,000 and ~446,700 ha at 1.0 m pond depth; and ~185,000 and ~250,000 ha at 1.5 m pond depth. Overall, deeper ponds reduced the risk. This study has developed a method to evaluate the negative impact of input pesticides to the environment from agricultural use related to fluctuation of aquaculture risk areas. The research indicates the potential relationship between pesticide input and the risk areas for aquaculture. The model has several significant uses: 1) it can provide information to policy makers for a more harmonized development of both aquaculture and agriculture in the Mekong delta in the future, 2) it provides data for aquaculture investment analysis to decrease the hazards caused by pesticide impacts, and 3) it provides a model capable of application to wide field scenarios and suitable for any pesticide type

Electromagnetic detection of axions

Photon-to-axion conversions in the static electromagnetic fields are reconsidered in detail by using the Feynman diagram techniques. The differential cross sections are presented for the conversions in the presence of the electric field of the flat condenser as well as in the magnetic field of the solenoid. Based on our results a laboratory experiment for the production and the detection of the axions is described. This experiment will exploit the axion decay constant as well as the axion mass.Comment: 7 pages, latex, no figures, to appear in Phys. Lett.

Key Determinants on Switching Intention in Cambodian Banking Market

The current study investigated the determinants affecting customers’ intentions to switch banks, with a focus on the determinants of service quality, convenience, perceived value, and customer satisfaction. Furthermore, Path Analysis was applied in this study to analyse the data collected from 323 participants. The findings highlighted that service quality significantly influenced perceived value, while convenience significantly influenced both perceived value and customer satisfaction. Likewise, perceived value significantly affected customer satisfaction. Finally, both perceived value and customer satisfaction, significantly impacted on switching intentions. As a result, the present study can help all service providers, especially banks, to better understand the significant impacts of these influential determinants on switching intentions. As a result, it can help them to design and develop an appropriate strategy to enhance these determinants and reduce future switching intentions

Free group automorphisms, invariant orderings and topological applications

We are concerned with orderable groups and particularly those with orderings invariant not only under multiplication, but also under a given automorphism or family of automorphisms. Several applications to topology are given: we prove that the fundamental groups of hyperbolic nonorientable surfaces, and the groups of certain fibred knots are bi-orderable. Moreover, we show that the pure braid groups associated with hyperbolic nonorientable surfaces are left-orderable.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol1/agt-1-15.abs.htm

The Magellan/IMACS Catalog of Optical Supernova Remnant Candidates in M83

We present a new optical imaging survey of supernova remnants in M83, using data obtained with the Magellan I 6.5m telescope and IMACS instrument under conditions of excellent seeing. Using the criterion of strong [S II] emission relative to Halpha, we confirm all but three of the 71 SNR candidates listed in our previous survey, and expand the SNR candidate list to 225 objects, more than tripling the earlier sample. Comparing the optical survey with a new deep X-ray survey of M83 with Chandra, we find 61 of these SNR candidates to have X-ray counterparts. We also identify an additional list of 46 [O III] -selected nebulae for follow-up as potential ejecta-dominated remnants, seven of which have associated X-ray emission that makes them strong candidates. Some of the other [O III]-bright objects could also be normal ISM-dominated supernova remnants with shocks fast enough to doubly ionize oxygen, but with Halpha and [S II] emission faint enough to have been missed. A few of these objects may also be H II regions with abnormally high [O III] emission compared with the majority of M83 H II regions, compact nebulae excited by young Wolf-Rayet stars, or even background AGN. The supernova remnant Halpha luminosity function in M83 is shifted a factor of ~ 4.5x higher than for M33 supernova remnants, indicative of a higher mean ISM density in M83. We describe the search technique used to identify the supernova remnant candidates and provide basic information and finder charts for the objects.Comment: 40 pages, 15 figures, accepted for ApJ