3,161 research outputs found
The Full Automorphism Group of a Cyclic -gonal Surface
If is prime, a compact Riemann surface of genus is called
cyclic -gonal if it admits a cyclic group of automorphisms of order
such that the quotient space has genus 0. If in addition
is not normal in the full automorphism , then we call a non-normal
cyclic -gonal group. In the following we classify all non-normal -gonal
groups.Comment: 18 pages, 5 figure
The Origin, Succession, and Predicted Metabolism of Bacterial Communities Associated with Leaf Decomposition.
Intraspecific variation in plant nutrient and defensive traits can regulate ecosystem-level processes, such as decomposition and transformation of plant carbon and nutrients. Understanding the regulatory mechanisms of ecosystem functions at local scales may facilitate predictions of the resistance and resilience of these functions to change. We evaluated how riverine bacterial community assembly and predicted gene content corresponded to decomposition rates of green leaf inputs from red alder trees into rivers of Washington State, USA. Previously, we documented accelerated decomposition rates for leaves originating from trees growing adjacent to the site of decomposition versus more distant locales, suggesting that microbes have a "home-field advantage" in decomposing local leaves. Here, we identified repeatable stages of bacterial succession, each defined by dominant taxa with predicted gene content associated with metabolic pathways relevant to the leaf characteristics and course of decomposition. "Home" leaves contained bacterial communities with distinct functional capacities to degrade aromatic compounds. Given known spatial variation of alder aromatics, this finding helps explain locally accelerated decomposition. Bacterial decomposer communities adjust to intraspecific variation in leaves at spatial scales of less than a kilometer, providing a mechanism for rapid response to changes in resources such as range shifts among plant genotypes. Such rapid responses among bacterial communities in turn may maintain high rates of carbon and nutrient cycling through aquatic ecosystems.IMPORTANCE Community ecologists have traditionally treated individuals within a species as uniform, with individual-level biodiversity rarely considered as a regulator of community and ecosystem function. In our study system, we have documented clear evidence of within-species variation causing local ecosystem adaptation to fluxes across ecosystem boundaries. In this striking pattern of a "home-field advantage," leaves from individual trees tend to decompose most rapidly when immediately adjacent to their parent tree. Here, we merge community ecology experiments with microbiome approaches to describe how bacterial communities adjust to within-species variation in leaves over spatial scales of less than a kilometer. The results show that bacterial community compositional changes facilitate rapid ecosystem responses to environmental change, effectively maintaining high rates of carbon and nutrient cycling through ecosystems
Intrinsic Josephson Microwave Phase Shifter
Phase shifters are a vital part of communication systems, and research into superconducting electronic devices has highlighted the possible application of Josephson junctions in this field of research. Intrinsic Josephson junctions (IJJs) are created by the high-density atomic-scale superconducting/insulator layering found within high temperature superconductors, such as Tl2Ba2CaCu2O8. This means a large number of series junctions are able to be created in relatively small dimensions in comparison to extrinsic devices limited in size by fabrication techniques. By designing IJJ tracks with large numbers of junctions in series, the phase shift from each individual junction sums to produce significant measurable phase tunability. I have studied the characteristics of IJJ tracks fabricated in Tl2Ba2CaCu2O8 to investigate the their use as microwave phase shifters. This involved determining the optimum track dimensions to ensure true Josephson behaviour of the IJJs by measuring the current-voltage characteristics at 4.2K. I have derived the equations governing the phase bias relationship, used these to simulate the expected junction characteristics based on the track parameters. These were then compared with the measured results and discussed in the context of other research in the field. Based on the phase tunability measured in the Tl2Ba2CaCu2O8 tracks, I then proceed to investigate the possible use of the coplanar IJJ transmission line as a parametric amplifier. The results presented highlight a small region of gain coupled to a geometric resonance, however this is not due to any parametric effect. Further research in this area is required to excite parametric amplification from these devices
Design against crime european exchange tool. Guidance for designing against crime across Europe
This guidanceâa key output of the European Commission's AGIS 2006 project led by the University of Salfordâaims to help local authorities, planners, police, academics, design professionals and developers identify methods of addressing crime prevention through design and planning, tailoring the approach to the European context. Guidance on addressing fear of crime and insecurity is also provided. The guidance is divided into the following sections:
àč Design-led Crime Prevention Approaches
àč Advice for European countries
àč Further information and reference
On automorphisms of algebraic curves
An irreducible, algebraic curve of genus defined
over an algebraically closed field of characteristic \mbox{char } \, k = p
\geq 0, has finite automorphism group \mbox{Aut} (\mathcal X_g). In this
paper we describe methods of determining the list of groups \mbox{Aut}
(\mathcal X_g) for a fixed . Moreover, equations of the corresponding
families of curves are given when possible
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Thermal processing and interactions of ethyl formate in model astrophysical ices containing water and ethanol
Temperature programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS) have been used to investigate the interactions between ethyl formate and water and ethyl formate and ethanol in model astrophysical ices adsorbed on a graphitic model grain surface. Experiments show that the ethyl formate forms hydrogen bonds to both water and ethanol via the oxygen lone pairs. This leads to the observation of shifts in the vibrational wavenumber of the C=O and C-O-C modes of ethyl formate, which can potentially be used to identify the environment of this complex organic molecule in astronomical observations. TPD data show that the interaction of ethyl formate with water is stronger than that with ethanol, with an additional species being observed in the TPD spectrum corresponding to the desorption of ethyl formate directly bonded to the water ice surface. The desorption energy of ethyl formate adsorbed on water ice was found to be 48.5 kJ mol-1, compared to 43.2 kJ mol-1 for pure ethyl formate monolayers. Ethyl formate also traps in water ice, and undergoes volcano desorption at the water amorphous to crystalline phase transition temperature. In contrast to the water, ethanol has very little effect on the desorption of ethyl formate, with the two species behaving independently even in a co-deposited ice
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The national facility physics and diagnostics
This paper presents a description of the National Ignition Facility, some of the physics experiments that will be performed on it and a description of some of the diagnostics needed to complete these experiments. Experiments are presented under the headings of: ignition physics, weapons physics or high-energy-density experimental science, weapons effects, and basic science and inertial fusion energy. The diagnostics discussed are primarily those that will be provided for early operation
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