An assessment of the physical, chemical, and biological properties of Christine Lake, NH

As part of a comparative assessment of seven New Hampshire lakes, performed throughout the month of September 2003, students and faculty from the University of New Hampshire’s Center for Freshwater Biology sampled Christine Lake in Stark, NH. The goal of the study was to quantify the lake’s physical, chemical, and biological properties and compare it to the six other lakes studied, as well as to results from identical sampling of Christine Lake in June, 2003. Christine Lake is an oligotrophic lake with very little primary production and low densities of zooplankton. Nutrient levels were low, likely due to the forested composition of the lake’s watershed and the small number of homes on the lake’s shore. The low phosphorus concentration and high N:P ratio (TN:TP = 50) typify a phosphoruslimited system which is likely to be the cause of the minimal algal abundance (1.6 ± 0.1 µg L-1 average epilimnetic chlorophyll compared to 39.4 ± 1.0 µg L-1 in eutrophic York Pond). Predation by young Brook and Brown Trout most likely favored the increased densities of the smaller zooplankter Bosmina (average body length: 0.42 mm ± 0.01), as they are not readily visible to the trout like the larger Daphnia (average body length: 1.39 mm ± 0.03). Evidence for increased predation on Daphnia can be seen in their location in the water column (8 m and 12 m) which indicates migration to deeper waters to avoid fish predation. The depressed density and size of the zooplankton in the lake are most likely due to a lack of suitable grazing material and predation from the planktivorous fish population. Interactions between zooplankton and higher trophic levels, as well as phytoplankton, are discussed in the context of a model food web

Electroweakino constraints from LHC data

We investigate the sensitivity of existing LHC searches to the charginos and neutralinos of the MSSM when all the other superpartners are decoupled. In this limit, the underlying parameter space reduces to a simple four-dimensional set $\{M_1,\,M_2,\,\mu,\,\tan\beta\}$. We examine the constraints placed on this parameter space by a broad range of LHC searches taking into account the full set of relevant production and decay channels. We find that the exclusions implied by these searches exceed existing limits from LEP only for smaller values of the Bino mass $M_1 \lesssim 150$ GeV. Our results have implications for MSSM dark matter and electroweak baryogenesis.Comment: 30 pages, 15 figure

Satellite appendage tie down cord Patent

Design and construction of satellite appendage tie-down cor

Extending LHC Coverage to Light Pseudoscalar Mediators and Coy Dark Sectors

Many dark matter models involving weakly interacting massive particles (WIMPs) feature new, relatively light pseudoscalars that mediate dark matter pair annihilation into Standard Model fermions. In particular, simple models of this type can explain the gamma ray excess originating in the Galactic Center as observed by the Fermi Large Area Telescope. In many cases the pseudoscalar's branching ratio into WIMPs is suppressed, making these states challenging to detect at colliders through standard dark matter searches. Here, we study the prospects for observing these light mediator states at the LHC without exploiting missing energy techniques. While existing searches effectively probe pseudoscalars with masses between 5 - 14 GeV and above 90 GeV, the LHC reach can be extended to cover much of the interesting parameter space in the intermediate 20 - 80 GeV mass range in which the mediator can have appreciable Yukawa-like couplings to Standard Model fermions but would have escaped detection by LEP and other experiments. Models explaining the Galactic Center excess via a light pseudoscalar mediator can give rise to a promising signal in this regime through the associated production of the mediator with bottom quarks while satisfying all other existing constraints. We perform an analysis of the backgrounds and trigger efficiencies, detailing the cuts that can be used to extract the signal. A significant portion of the otherwise unconstrained parameter space of these models can be conclusively tested at the 13 TeV LHC with 100 fb$^{-1}$, and we encourage the ATLAS and CMS collaborations to extend their existing searches to this mass range.Comment: 27 pages + 3 appendices, 20 figures, 7 table

Unravelling an Extra Neutral Gauge Boson at the LHC using Third Generation Fermions

We study the potential to use measurements of extra neutral gauge bosons (Z') properties in pp collisions at the Large Hadron Collider to unravel the underlying physics. We focus on the usefulness of third generation final states (tau, b, t) in distinguishing between models with non-universal Z'-fermion couplings. We present an update of discovery limits of Z's including the 2010-2011 LHC run and include models with non-universal couplings. We show how ratios of sigma(pp -> Z' -> ttbar), sigma(pp -> Z' -> bbbar), and sigma(pp -> Z' -> tau^+tau^-) to sigma(pp -> Z' -> mu^+mu^-) can be used to distinguish between models and measure parameters of the models. Of specific interest are models with preferential couplings, such as models with generation dependent couplings. We also find that forward-backward asymmetry measurements with third generation fermions in the final state could provide important input to understanding the nature of the Z'. Understanding detector resolution and efficiencies will be crucial for extracting results

Using Final State Pseudorapidities to Improve s-channel Resonance Observables at the LHC

We study the use of final state particle pseudorapidity for measurements of s-channel resonances at the LHC. Distinguishing the spin of an s-channel resonance can, in principle, be accomplished using angular distributions in the centre-of-mass frame, possibly using a centre-edge asymmetry measurement, A_CE. In addition, forward-backward asymmetry measurements, A_FB, can be used to distinguish between models of extra neutral gauge bosons. In this note we show how these measurements can be improved by using simple methods based on the pseudorapidity of the final state particles and present the expected results for A_FB and A_CE for several representative models.Comment: 6 pages, 4 figures, 1 table; typos fixed, improved visibility of figures for greyscale printin

No evidence for oncogenic mutations in guanine nucleotide-binding proteins of human adrenocortical neoplasms

G-Proteins are membrane-bound heterotrimeric polypeptides that couple receptor signals to second messenger systems such as cAMP. Recently, point mutations at 2 codons of the highly preserved alpha-chain of Gs, the adenyl cyclase-stimulating G-protein, were found in GH-secreting pituitary tumors. These mutations resulted in constitutively activated Gs alpha and high intracellular cAMP levels. In addition, point mutations at similar codons of a different G-protein, G(i) alpha 2, were reported in adrenocortical neoplasms, suggesting a potential role of this isoform in the genesis of these tumors. We reevaluated the frequency of constitutively activating point mutations in the alpha- chain of the stimulatory (Gs alpha) and inhibitory (G(i) alpha 2) G- proteins in human adrenocortical tumors. Seven adrenocortical carcinomas, 2 human adrenocortical tumor cell lines, and 11 adrenocortical adenomas were studied. Genomic DNA was purified from either frozen tumor tissue or paraffin-embedded sections. Using specific primers and the polymerase chain reaction, DNA fragments surrounding codons 201 and 227 (Gs alpha) and 179 and 205 (G(i) alpha 2) were amplified and visualized on a 2% agarose gel. In a second asymmetric polymerase chain reaction, using nested primers, single stranded DNA was generated using 1-10 microL of the initial amplification mixture and directly sequenced using the dideoxy chain termination method of Sanger. We found no mutations at codons 201, 227 and 179, 205 of Gs alpha and G(i) alpha 2, respectively, in the tumors studied. We conclude that previously identified oncogenic point mutations in the stimulatory and inhibitory alpha-chain of G-proteins do not appear to be present at high frequency in adrenal neoplasms. Thus, the mechanism(s) of tumorigenesis in these tumors is different from that in GH-secreting adenomas and may involve oncogenic mutations of other cell constituents

Porous Carbon Based Solid Adsorbents for Carbon Dioxide Capture

The aim of this project is the design, synthesis and characterisation of porous carbon structures capable of the selective capture of carbon dioxide (CO2) from the exhaust gases of coal and gas post-combustion power stations. In such systems, the fossil fuel is burnt in an air environment producing CO2 as just one of a multi-component flue gas. This flue gas is expected to contain nitrogen and water among other constituents. It is at ambient pressures and temperatures of ≥323 K. Successful capture materials should have highly microporous structures, rapid sorption kinetics and be capable of repeated sorption/desorption cycles. To develop highly microporous carbon sorbents a range of porous materials have been synthesised using chemical and physical activation of precursors obtained through top down and bottom up approaches. Porosity has also been achieved in precursors through the controlled use of graphene exfoliation, melamine-formaldehyde resin aerogel formation, soft templates, controlled carbonisation and synthesis of microporous organic polymers. The role of nitrogen dopants (N-dopants) within the CO2 sorbent materials has also been investigated. To increase understanding and tune the sorbents performance, porous carbon structures have been synthesized containing: pyridine, pyrrole, quaternary and triazine nitrogen groups. Characterisation was achieved using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy, transmission electron microscopy X-ray diffraction, thermogravimetric analysis and nitrogen (N2) isotherms at 77 K. CO2 sorption analysis was carried out using volumetric and gravimetric analysis. The influence of N-dopants on the adsorbate-adsorbent interaction is characterised using CO2 volumetric isotherms, isosteric heats of adsorption and CO2/N2 selectivity analysis

Helmut Gollwitzer and Economic Justice: A Theopolitical Appreciation

Helmut Gollwitzer’s legacy as a politically concerned pastor and theologian is instructive for those today who want to take seriously both what Christian faith means for socio-economic justice and what that concern for socio-economic justice likewise means for the theological task. I treat three aspects of Gollwitzer’s work in order to highlight his significance for the contemporary situation: (1) his interesting application of the traditional idea of suum cuique, especially vis-à-vis Bonhoeffer; (2) the connection he draws between the Christian gospel and the necessity of combating economic-political privilege; and (3), his conclusions concerning Christian faith and theology’s failings in the face of atheist criticism of religion and what this means for continuing to do theology in the contemporary situation. One eye is kept on the Occupy Wall Street movement throughout the discussion in order to highlight how Gollwitzer’s thought illuminates matters in our own day