Sediment and pore water geochemistry of sediment cores, Potter Cove, King George Island

Redox-sensitive trace metals (Mn, Fe, U, Mo, Re), nutrients and terminal metabolic products (NO3-, NH4+, PO43-, total alkalinity) were for the first time investigated in pore waters of Antarctic coastal sediments. The results of this study reveal a high spatial variability in redox conditions in surface sediments from Potter Cove, King George Island, western Antarctic Peninsula. Particularly in the shallower areas of the bay the significant correlation between sulphate depletion and total alkalinity, the inorganic product of terminal metabolism, indicates sulphate reduction to be the major pathway of organic matter mineralisation. In contrast, dissimilatory metal oxide reduction seems to be prevailing in the newly ice-free areas and the deeper troughs, where concentrations of dissolved iron of up to 700 µM were found. We suggest that the increased accumulation of fine-grained material with high amounts of reducible metal oxides in combination with the reduced availability of metabolisable organic matter and enhanced physical and biological disturbance by bottom water currents, ice scouring and burrowing organisms favours metal oxide reduction over sulphate reduction in these areas. Based on modelled iron fluxes we calculate the contribution of the Antarctic shelf to the pool of potentially bioavailable iron (Feb) to be 6.9x10**3 to 790x10**3 t/yr. Consequently, these shelf sediments would provide an Feb flux of 0.35-39.5/mg/m**2/yr (median: 3.8 mg/m**2/yr) to the Southern Ocean. This contribution is in the same order of magnitude as the flux provided by icebergs and significantly higher than the input by aeolian dust. For this reason suboxic shelf sediments form a key source of iron for the high nutrient-low chlorophyll (HNLC) areas of the Southern Ocean. This source may become even more important in the future due to rising temperatures at the WAP accompanied by enhanced glacier retreat and the accumulation of melt water derived iron-rich material on the shelf.

Seawater carbonate chemistry and Globigerinoides sacculifer biological processes during experiments, 2010

The effect of carbonate ion concentration ([CO3]) on calcification rates estimated from shell size and weight was investigated in the planktonic foraminifera Orbulina universa and Globigerinoides sacculifer. Experiments on G. sacculifer were conducted under two irradiance levels (35 and 335 µmol photons m-2 s-1). Calcification was ca. 30% lower under low light than under high light, irrespective of the [CO3]. Both O. universa and G. sacculifer exhibited reduced final shell weight and calcification rate under low [CO3]. For the [CO3] expected at the end of the century, the calcification rates of these two species are projected to be 6 to 13% lower than the present conditions, while the final shell weights are reduced by 20 to 27% for O. universa and by 4 to 6% for G. sacculifer. These results indicate that ocean acidification would impact on calcite production by foraminifera and may decrease the calcite flux contribution from these organisms.

Location of bioelectricity plants in the Madrid Community based on triticale crop: a multicriteria methodology

This paper presents a work whose objective is, first, to quantify the potential of the triticale biomass existing in each of the agricultural regions in the Madrid Community through a crop simulation model based on regression techniques and multiple correlation. Second, a methodology for defining which area has the best conditions for the installation of electricity plants from biomass has been described and applied. The study used a methodology based on compromise programming in a discrete multicriteria decision method (MDM) context. To make a ranking, the following criteria were taken into account: biomass potential, electric power infrastructure, road networks, protected spaces, and urban nuclei surfaces. The results indicate that, in the case of the Madrid Community, the Campiña region is the most suitable for setting up plants powered by biomass. A minimum of 17,339.9 tons of triticale will be needed to satisfy the requirements of a 2.2 MW power plant. The minimum range of action for obtaining the biomass necessary in Campiña region would be 6.6 km around the municipality of Algete, based on Geographic Information Systems. The total biomass which could be made available in considering this range in this region would be 18,430.68 t.

Measurement of cytosolic, mitochondrial, and Golgi pH in single living cells with green fluorescent proteins

Many cellular events depend on a tightly compartmentalized distribution of H+ ions across membrane-bound organelles. However, measurements of organelle pH in living cells have been scarce. Several mutants of the Aequorea victoria green fluorescent protein (GFP) displayed a pH-dependent absorbance and fluorescent emission, with apparent pKa values ranging from 6.15 (mutations F64L/S65T/H231L) and 6.4 (K26R/F64L/S65T/Y66W/N146I/M153T/V163A/N164H/H231L) to a remarkable 7.1 (S65G/S72A/T203Y/H231L). We have targeted these GFPs to the cytosol plus nucleus, the medial/trans-Golgi by fusion with galactosyltransferase, and the mitochondrial matrix by using the targeting signal from subunit IV of cytochrome c oxidase. Cells in culture transfected with these cDNAs displayed the expected subcellular localization by light and electron microscopy and reported local pH that was calibrated in situ with ionophores. We monitored cytosolic and nuclear pH of HeLa cells, and mitochondrial matrix pH in HeLa cells and in rat neonatal cardiomyocytes. The pH of the medial/trans-Golgi was measured at steady-state (calibrated to be 6.58 in HeLa cells) and after various manipulations. These demonstrated that the Golgi membrane in intact cells is relatively permeable to H+, and that Cl− serves as a counter-ion for H+ transport and likely helps to maintain electroneutrality. The amenability to engineer GFPs to specific subcellular locations or tissue targets using gene fusion and transfer techniques should allow us to examine pH at sites previously inaccessible.

Sedation in paediatric intensive care

Paediatric intensive care is an expanding specialty that has been shown to improve the quality of care provided to critically ill children. An important aspect of the management of critically ill children includes the provision of effective sedation to reduce stress and anxiety during their stay in intensive care. However, to achieve effective and safe sedation in these children, is recognised as a challenge that is not without risk. Often children receive too much or too little sedation resulting in over sedation or under sedation respectively. These problems have arisen owing to a lack of information regarding altered pharmacokinetics and pharmacodynamics of medicines administered to critically ill children. In addition there are few validated sedation scoring systems in practice with which to monitor level of sedation and titrate medication appropriately. This study consisted of two stages. Stage 1 investigated the reproducibility and practicality of two observational sedation assessment scales for use in critically ill children. The two scales were different in design, the first being simple in design requiring a single assessment of the patient. The second was more complex in design requiring assessment of five patient parameters to obtain an overall sedation score. Both scales were found to achieve good reproducibility (kappa values 0.50 and 0.62 respectively). Practicality of each sedation scale was undertaken by obtaining nursing staff opinion about both scales using questionnaire and interview technique. It was established that nursing staff preferred the second, more complex sedation scale mainly because it was perceived to give a more accurate assessment of level of sedation and anxiety rather than merely level of sedation. Stage 2 investigated the pharmacokinetics and pharmacodynamics of midazolam in critically ill children. 52 children, aged between 0 and 18 years were recruited to the study and 303 blood samples taken to analyse midazolam and its metabolites, I-hydroxyrnidazolam (I-OR) and 4-hydroxymidazolam (4-0H). Analysis of plasma was undertaken using high performance liquid chromatography. A significant correlation was found between midazolam plasma concentration and sedative effect (r=0.598, p=O.OI). It was found that a midazolam plasma concentration of 223ng/ml (±31.9) achieved a satisfactory level of sedation. Only a poor correlation was found between dose of midazolam and plasma concentration of midazolam. Similarly only a poor correlation was found between sedative effect and dose of midazolam. Clearance of midazolam was found to be 6.3mllkglmin (±0.36), which is lower than that reported in healthy children (9.Il-13.3mllkg/min). Age related differences in midazolam clearance were observed in the study. Neonates produced the lowest clearance values (l.63mllkg/min), compared to children aged 1 to 12 months (8.52mllkg/min) who achieved the highest clearance values. Clearance was found to decrease after the age of 12 months to values of 5.34mllkglmin in children aged 7 years and above. Patients with renal (n=5) and liver impairment (n~4) were found to have reduced midazolam clearance (1.37 and 0.74ml/kg/min respectively). Plasma concentrations of I-OH and 4-0H ranged from 0-5 1 89nglml and 0-27 Inglml respectively. All children were found to be capable of producing both metabolites irrespective of age, although no trend was established between age and extent of production of either metabolite. Disease state was found to affect production of l-OH. Patients with renal impairment (n=5) produced the lowest I-OH midazolam plasma ratio (0.059) compared to patients with head injury (0.858). Patients with severe liver impairment were found to be capable of manufacturing both metabolites despite having a severely damaged liver.

Anterior eye health recording

Aims: To survey eye care practitioners from around the world regarding their current practice for anterior eye health recording to inform guidelines on best practice. Methods: The on-line survey examined the reported use of: word descriptions, sketching, grading scales or photographs; paper or computerised record cards and whether these were guided by proforma headings; grading scale choice, signs graded, level of precision, regional grading; and how much time eye care practitioners spent on average on anterior eye health recording. Results: Eight hundred and nine eye care practitioners from across the world completed the survey. Word description (p <. 0.001), sketches (p = 0.002) and grading scales (p <. 0.001) were used more for recording the anterior eye health of contact lens patients than other patients, but photography was used similarly (p = 0.132). Of the respondents, 84.5% used a grading scale, 13.5% using two, with the original Efron (51.6%) and CCLRU/Brien-Holden-Vision-Institute (48.5%) being the most popular. The median features graded was 11 (range 1-23), frequency from 91.6% (bulbar hyperaemia) to 19.6% (endothelial blebs), with most practitioners grading to the nearest unit (47.4%) and just 14.7% to one decimal place. The average time taken to report anterior eye health was reported to be 6.8. ±. 5.7. min, with the maximum time available 14.0. ±. 11. min. Conclusions: Developed practice and research evidence allows best practice guidelines for anterior eye health recording to be recommended. It is recommended to: record which grading scale is used; always grade to one decimal place, record what you see live rather than based on how you intend to manage a condition; grade bulbar and limbal hyperaemia, limbal neovascularisation, conjunctival papillary redness and roughness (in white light to assess colouration with fluorescein instilled to aid visualisation of papillae/follicles), blepharitis, meibomian gland dysfunction and sketch staining (both corneal and conjunctival) at every visit. Record other anterior eye features only if they are remarkable, but indicate that the key tissue which have been examined.

Maintaining tree islands in the Florida Everglades: nutrient redistribution is the key

The Florida Everglades is an oligotrophic wetland system with tree islands as one of its most prominent landscape features. Total soil phosphorus concentrations on tree islands can be 6 to 100 times greater than phosphorus levels in the surrounding marshes and sloughs, making tree islands nutrient hotspots. Several mechanisms are believed to redistribute phosphorus to tree islands: subsurface water flows generated by evapotranspiration of trees, higher deposition rates of dry fallout, deposition of guano by birds and other animals, groundwater upwelling, and bedrock mineralization by tree exudates. A conceptual model is proposed, in which the focused redistribution of limiting nutrients, especially phosphorus, onto tree islands controls their maintenance and expansion. Because of increased primary production and peat accretion rates, the redistribution of phosphorus can result in an increase in both tree island elevation and size. Human changes to hydrology have greatly decreased the number and size of tree islands in parts of the Everglades. The proposed model suggests that the preservation of existing tree islands, and ultimately of the Everglades landscape, requires the maintenance of these phosphorus redistribution mechanisms.

Radiocarbon age of bottom sediments from the Yenisei Gulf and the Kara Sea

Sedimentation rates and bottom sediment ages were determined by 14C method in the Kara Sea and the Yenisei River marginal filter. Age of carbon supplied by the Yenisei River is estimated to be 6.9 ka. As supplied carbon mixes with young biogenic carbon under influence of plankton and benthos young carbon flux (planktogenic) sharply diminishes. This has been inferred from studies of organic matter in sedimentary traps deployed along sections from the Yenisei River mouth to 76°N. The major part (70-80%) of organic carbon in bottom sediments of the Kara and Laptev Seas is ancient (Holocene). Planktogenic part comprises only 20-30%. In the Central Arctic Basin percentage of planktogenic organic matter in bottom sediments is still lower, the major part being associated with supply of ancient terrigenous organic material of low nutritional value for organisms. Determinations of sedimentation rates and recent matter fluxes from sedimentary traps served as a basis for locating a sedimentary depocenter in the Yenisei River both for present time and for geological past. Regularities of variations of sediment matter fluxes in the marginal filter were studied.

The Kepler-454 system: a small, not-rocky inner planet, a Jovian world, and a distant companion

Kepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like star that hosts a transiting planet candidate in a 10.6 day orbit. From spectroscopy, we estimate the stellar temperature to be 5687 ± 50 K, its metallicity to be [m/H] = 0.32 ± 0.08, and the projected rotational velocity to be v sin i <2.4 km s^-1. We combine these values with a study of the asteroseismic frequencies from short cadence Kepler data to estimate the stellar mass to be , the radius to be 1.066 ± 0.012 R_o, and the age to be Gyr. We estimate the radius of the 10.6 day planet as 2.37 ± 0.13 R_⊕. Using 63 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 36 observations made with the HIRES spectrograph at the Keck Observatory, we measure the mass of this planet to be 6.8 ± 1.4 M_⊕. We also detect two additional non-transiting companions, a planet with a minimum mass of 4.46 ± 0.12 M_J in a nearly circular 524 day orbit and a massive companion with a period >10 years and mass >12.1 M_J. The 12 exoplanets with radii ⊕ and precise mass measurements appear to fall into two populations, with those ⊕ following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76 ± 0.73 g cm^-3, Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas.

Absolute cross sections for dissociative electron attachment to HCCCN

New absolute cross sections for dissociative electron attachment to HCCCN (cyanoacetylene or propiolonitrile) in the range of 0-10 eV electron energy are presented here, which have been determined from a new analysis of previously reported data (Graupner et al 2006 New J. Phys. 8 117). The highest cross sections are observed for the formation of CN^- at 5.3 eV and CCCN^- at 5.1 eV; approximately 0.06 Ų and 0.05 Ų respectively. As part of the re-analysis, it was necessary to determine absolute cross sections for electron-impact ionization of HCCCN with the binary-encounter Bethe method. These electron-impact ionization absolute cross sections for HCCCN are also presented here; the maximum value was found to be ∼6.6 Ų at ∼80 eV.

Microstructures layering, mechanisms in the middle waters of the Persian Gulf

Layered structures, known as micro structures in marine environments are common features of which their formation mechanisms are first reviewed. Some methods of measuring such features based on the measurements and theories are presented for the Persian Gulf. This includes determination of layers with temperature inversion (TI) associated with double diffusive convection (DDC). The relevant associated parameters are estimated from ROPME CTD data for late winter and early summer of 1992. Only in certain parts temperature inversion and DDC are observed which seem to produce layered structures. Observations show that the places with TI and DDC are mainly confined to the frontal regions where the water entering the Persian Gulf and water exiting it meet, nearly along the axis of the Gulf. TI and DDC is mainly observer in the northern bound of the front. Typical density ratio for regions with TI and DDC is 0.7 to 0.2 and the mean depth is at about 37 ± 3 m for the Persian Gulf. TI and DDC are also found in the outflow from the Persian Gulf to the Oman Gulf which is found to be at a depth of about 250 m. Horizontal addiction and reduction of solar heating seem to be the main reasons in producing layers with TI and DDC. It is also found that the regime of DDC in the Persian Gulf is more diffusive and the flow associated with intrusion layers with TI is non-isopycnal (more unstable). However for the Oman sea both diffusive and finger regime are observed and the flow is inferred to be isopycnal (more stable statically). Typical heat and salt fluxes due to DDC are found to be 6 W/m2 and 0.36 W/m2 respectively. Effective salinity diffusivity, Ks and heat diffusivity, Kr have been estimated for the places with DDC in the Persian Gulf and Oman Gulf (Ks=1.1 *10-7 m2/s, KT= 1.88*10-6 m2/s). Their values are within the values obtained by others. The buoyancy frequency for the Persian Gulf with typical mean value of 0.05s-1 is much higher than these of the free Oceans. Such large values of N (typically 0.05 s-1) indicate that processes such as tide can produce strong internal waves which may be another factor in producing layered structures. This requires separate study.

The IL-6 response to Chlamydia from primary reproductive epithelial cells is highly variable and may be involved in differential susceptibility to the immunopathological consequences of chlamydial infection

Background Chlamydia trachomatis infection results in reproductive damage in some women. The process and factors involved in this immunopathology are not well understood. This study aimed to investigate the role of primary human cellular responses to chlamydial stress response proteases and chlamydial infection to further identify the immune processes involved in serious disease sequelae. Results Laboratory cell cultures and primary human reproductive epithelial cultures produced IL-6 in response to chlamydial stress response proteases (CtHtrA and CtTsp), UV inactivated Chlamydia, and live Chlamydia. The magnitude of the IL-6 response varied considerably (up to 1000 pg ml-1) across different primary human reproductive cultures. Thus different levels of IL-6 production by reproductive epithelia may be a determinant in disease outcome. Interestingly, co-culture models with either THP-1 cells or autologous primary human PBMC generally resulted in increased levels of IL-6, except in the case of live Chlamydia where the level of IL-6 was decreased compared to the epithelial cell culture only, suggesting this pathway may be able to be modulated by live Chlamydia. PBMC responses to the stress response proteases (CtTsp and CtHtrA) did not significantly vary for the different participant cohorts. Therefore, these proteases may possess conserved innate PAMPs. MAP kinases appeared to be involved in this IL-6 induction from human cells. Finally, we also demonstrated that IL-6 was induced by these proteins and Chlamydia from mouse primary reproductive cell cultures (BALB/C mice) and mouse laboratory cell models. Conclusions We have demonstrated that IL-6 may be a key factor for the chlamydial disease outcome in humans, given that primary human reproductive epithelial cell culture showed considerable variation in IL-6 response to Chlamydia or chlamydial proteins, and that the presence of live Chlamydia (but not UV killed) during co-culture resulted in a reduced IL-6 response suggesting this response may be moderated by the presence of the organism.

Revisiting SW J2000.6+3210: a persistent Be X-ray pulsar?

We present a detailed timing and spectral analysis of the Be X-ray binary SW J2000.6+3210 discovered by the Burst Alert Telescope Galactic plane survey. Two Suzaku observations of the source made at six months interval, reveal pulsations at similar to 890 s for both observations with a much weaker pulse fraction in the second one. Pulsations are clearly seen in the energy band of 0.3-10 keV of X-ray Imaging Spectrometer for both observations and at high energies up to 40 keV for the second observation. The broad-band X-ray spectrum is consistent with a power-law and high-energy cut-off model along with a hot blackbody component. No change in spectral parameters is detected between the observations. We have also analysed several short observations of the source with Swift/XRT and detected only a few per cent variation in flux around a mean value of 3.5 x 10(-11) erg cm(-2) s(-1). The results indicate that SW J2000.6+3210 is a member of persistent Be X-ray binaries which have the same broad characteristics as this source.