Ecological and physiological studies on freshwater autotrophic picoplankton

A series of studies were conducted to ascertain the importance of autotrophic picoplankton (0.2 - 2.0 fm in the longest dimension) in freshwaters. These included surveys of populations in lakes and rivers, and experiments on strains which had been isolated in clonal, axenic culture. Methods were developed to preserve, count and identify autotrophic picoplankton. Epifluorescence microscopy was used routinely throughout the study and it was shown that cells could be preserved in buffered formalin or glutaraldehyde for at least 12 months without a loss in cell count. Autotrophic picoplankton fluoresced red or orange depending on the photosynthetic pigments present, and a method based on fluorescence characteristics was developed to distinguish cyanobacterial from eukaryotic cells. Eukaryotes fluoresced most intensely under blue excitation light and were barely visible under green excitation light and cyanobacterial cells had the reverse response. In addition, fluorescence from eukaryotic cells faded faster than the fluorescence from cyanobacterial cells. Samples from standing waters from around the world were collected from 5 continents in a survey to discover how widespread autotrophic picoplankton are in the world; densities ranged from 1.02 x 10(^6) from a pool in Saudi Arabia to 1.20 x 10(^6) in Ennerdale Water in the UK. A survey of 30 lakes in northern England and Scotland revealed autotrophic picoplankton in every sample. Cell densities ranged from a minimum of 1.02 x 10(^2) in Esthwaite Water to a maximum of 4.26 x 10(^5) in Ennerdale Water. In two mountain streams the only autotrophic picoplankton found were aberrant. Studies on the seasonality of autotrophic picoplankton from 10 UK lakes showed that population densities differed by at least two orders of magnitude in a year. In every lake densities reached a maximum at mid- to late summer and highest densities were found in nutrient-poor waters. There was a marked difference in the relative abundance of orange and red fluorescing cells in all lakes. A number of standard methods were used to isolate and purify strains of autotrophic picoplankton, including a novel method using a laser flow cytometer to purify bacterized unialgal cultures. 14 strains were studied (9 obtained the author) and they demonstrated different growth rates when grown with different nitrogen substrates and when grown under different photon flux density. Twelve strains showed cell-bound phosphomonoesterase activity at pH 10.3 and nine strains showed cell bound phosphodiesterase activity at pH 10.3. No strain showed evidence of nitrogen fixation, chemoheterotrophic growth, desiccation tolerance, motility nor chromatic adaptation

Finding Shuffle Words That Represent Optimal Scheduling of Shared Memory Access

In the present paper, we introduce and study the problem of computing, for any given finite set of words, a shuffle word with a minimum so-called scope coincidence degree. The scope coincidence degree is the maximum number of different symbols that parenthesise any position in the shuffle word. This problem is motivated by an application of a new automaton model and can be regarded as the problem of scheduling shared memory accesses of some parallel processes in a way that minimises the number of memory cells required. We investigate the complexity of this problem and show that it can be solved in polynomial time

Geochemical analysis of bulk marine sediment by Inductively Coupled Plasma–Atomic Emission Spectroscopy on board the JOIDES Resolution

Geochemical analyses on board the JOIDES Resolution have been enhanced with the addition of a Jobin-Yvon Ultrace inductively coupled plasma-atomic emission spectrometer (ICP-AES) as an upgrade from the previous X-ray fluorescence facility. During Leg 199, we sought to both challenge and utilize the capabilities of the ICP-AES in order to provide an extensive bulk-sediment geochemical database during the cruise. These near real-time analyses were then used to help characterize the recovered sedimentary sequences, calculate mass accumulation rates of the different sedimentary components, and assist with cruise and postcruise sampling requests. The general procedures, sample preparation techniques, and basic protocol for ICP-AES analyses on board ship are outlined by Murray et al. (2000) in Ocean Drilling Program Tech Note, 29. We expand on those concepts and offer suggestions for ICP-AES methodology, calibration by standard reference materials, data reduction procedures, and challenges that are specific to the analysis of bulk-sediment samples. During Leg 199, we employed an extensive bulk-sediment analytical program of ~600 samples of varying lithologies, thereby providing several opportunities for refinement of techniques. We also discuss some difficulties and challenges that were faced and suggest how to alleviate such occurrences for sedimentary chemical analyses during future legs

Increased risk of HPV-associated genital cancers in men and women as a consequence of pre-invasive disease

To assess the excess risk of HPV‐associated cancer (HPVaC) in two at‐risk groups – women with a previous diagnosis of high grade cervical intraepithelial neoplasia (CIN3) and both men and women treated for non‐cervical pre‐invasive ano‐genital disease. All CIN3 cases diagnosed in 1989‐2015 in Scotland were extracted from the Scottish cancer registry (SMR06). All cases of pre‐invasive penile, anal, vulval, and vaginal disease diagnosed in 1990‐2015 were identified within the NHS pathology databases in the two largest NHS health boards in Scotland. Both were linked to SMR06 to extract subsequent incidence of HPVaC following the diagnosis of CIN3 or pre‐invasive disease. Standardised incidence ratios were calculated for the risk of acquiring HPVaC for the two at‐risk groups compared with the general Scottish population. Among 69714 females in Scotland diagnosed with CIN3 (890360.9 person‐years), 179 developed non‐cervical HPVaC. CIN3 cases were at 3.2‐fold (95% CI: 2.7 to 3.7) increased risk of developing non‐cervical HPVaC, compared to the general female population. Among 1235 patients diagnosed with non‐cervical pre‐invasive disease (9667.4 person‐years), 47 developed HPVaC. Individuals with non‐cervical pre‐invasive disease had a substantially increased risk of developing HPVaC ‐ 15.5‐fold (95% CI: 11.1 to 21.1) increased risk for females and 28‐fold (11.3 to 57.7) increased risk for males. We report a significant additional risk of HPV‐associated cancer in those have been diagnosed with pre‐invasive HPV‐associated lesions including but not confined to the cervix. Uncovering the natural history of pre‐invasive disease has potential for determining screening, prevention and treatment

The re-regulation of broadcasting: Or the mill owners’ triumph

Discusses the driving forces behind the Communications Bill 2001 of Great Britain. Terms of the bill; Arguments concerning the re-regulation

A new terrestrial palaeoenvironmental record from the Bering Land Bridge and context for human dispersal

Palaeoenvironmental records from the now-submerged Bering Land Bridge (BLB) covering the Last Glacial Maximum (LGM) to the present are needed to document changing environments and connections with the dispersal of humans into North America. Moreover, terrestrially based records of environmental changes are needed in close proximity to the re-establishment of circulation between Pacific and Atlantic Oceans following the end of the last glaciation to test palaeo-climate models for the high latitudes. We present the first terrestrial temperature and hydrologic reconstructions from the LGM to the present from the BLB’s south-central margin. We find that the timing of the earliest unequivocal human dispersals into Alaska, based on archaeological evidence, corresponds with a shift to warmer/wetter conditions on the BLB between 14 700 and 13 500 years ago associated with the early Bølling/Allerød interstadial (BA). These environmental changes could have provided the impetus for eastward human dispersal at that time, from Western or central Beringia after a protracted human population standstill. Our data indicate substantial climate-induced environmental changes on the BLB since the LGM, which would potentially have had significant influences on megafaunal and human biogeography in the region. © 2018 The Authors

Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations

We present new precision measurements of the psi(2S) total and partial widths from excitation curves obtained in antiproton-proton annihilations by Fermilab experiment E835 at the Antiproton Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p -> J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +- 4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp / Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise measurements to date.Comment: 17 pages, 3 figures, 3 tables. Final manuscript accepted for publication in Phys. Lett. B. Parts of the text slightly expanded or rearranged; results are unchange

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare

Nash Equilibria in Discrete Routing Games with Convex Latency Functions

In a discrete routing game, each of n selfish users employs a mixed strategy to ship her (unsplittable) traffic over m parallel links. The (expected) latency on a link is determined by an arbitrary non-decreasing, non-constant and convex latency function φ. In a Nash equilibrium, each user alone is minimizing her (Expected) Individual Cost, which is the (expected) latency on the link she chooses. To evaluate Nash equilibria, we formulate Social Cost as the sum of the users ’ (Expected) Individual Costs. The Price of Anarchy is the worst-case ratio of Social Cost for a Nash equilibrium over the least possible Social Cost. A Nash equilibrium is pure if each user deterministically chooses a single link; a Nash equilibrium is fully mixed if each user chooses each link with non-zero probability. We obtain: For the case of identical users, the Social Cost of any Nash equilibrium is no more than the Social Cost of the fully mixed Nash equilibrium, which may exist only uniquely. Moreover, instances admitting a fully mixed Nash equilibrium enjoy an efficient characterization. For the case of identical users, we derive two upper bounds on the Price of Anarchy: For the case of identical links with a monomial latency function φ(x) = x d, the Price of Anarchy is the Bell number of order d + 1. For pure Nash equilibria, a generic upper bound from the Wardrop model can be transfered to discrete routing games. For polynomial latency functions with non-negative coefficients and degree d, this yields an upper bound of d + 1. For th