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  • 1
    Publication Date: 2015-07-29
    Description: Phytoplankton growth and biomass accumulation vary spatially and temporally in the Ross Sea, largely as a function of ice concentrations, vertical mixing depths, and iron concentrations. To assess the role of vertical mixing in bloom initiation, we used a high-resolution numerical model to estimate changes in mixed layer depths from October 1 through early December, the period where phytoplankton growth begins and biomass accumulates, and estimate critical depths for this period. Mixed layers in October ranged from the complete water column (〉600 m) to ca. 200 m; over a 60-day period, the mixed layers decreased on average by 70%. Estimated critical depths were exceeded in October, but would allow growth to proceed in late October due to shoaling of mixed layer depths, consistent with the known onset of the spring bloom in the Ross Sea. We also analysed a series of stations sampled near the Ross Ice Shelf during January 2012. Mean vertical profiles for the stations indicated deep vertical mixing; mixed layer depths averaged 60 m and ranged up to 96 m. Chlorophyll concentrations within the mixed layer averaged 6.60 µg l –1 , and the pigment contributions were dominated by Phaeocystis antarctica . We suggest that this mesoscale region near the ice shelf is elevated in phytoplankton biomass due to frequent mixing events that redistribute biomass to depth and replenish nutrients, which in turn are utilized by an assemblage capable of utilizing low mean irradiance levels. Thus, the deep mixed layers and high biomass concentrations represent growth over long periods under reduced mixing punctuated by short periods of deeper vertical mixing that redistribute biomass. Water column vertical mixing and phytoplankton biomass in the Ross Sea are consistent with the critical depth concept as originally proposed by Sverdrup.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 2
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    Oxford University Press
    Publication Date: 2013-03-21
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 3
    Publication Date: 2014-02-13
    Description: Improving the accuracy of the marine gravity field requires both improved altimeter range precision and dense track coverage. After a hiatus of more than 15 yr, a wealth of suitable data is now available from the CryoSat-2, Envisat and Jason-1 satellites. The range precision of these data is significantly improved with respect to the conventional techniques used in operational oceanography by retracking the altimeter waveforms using an algorithm that is optimized for the recovery of the short-wavelength geodetic signal. We caution that this new approach, which provides optimal range precision, may introduce large-scale errors that would be unacceptable for other applications. In addition, CryoSat-2 has a new synthetic aperture radar (SAR) mode that should result in higher range precision. For this new mode we derived a simple, but approximate, analytic model for the shape of the SAR waveform that could be used in an iterative least-squares algorithm for estimating range. For the conventional waveforms, we demonstrate that a two-step retracking algorithm that was originally designed for data from prior missions (ERS-1 and Geosat) also improves precision on all three of the new satellites by about a factor of 1.5. The improved range precision and dense coverage from CryoSat-2, Envisat and Jason-1 should lead to a significant increase in the accuracy of the marine gravity field.
    Print ISSN: 0956-540X
    Electronic ISSN: 1365-246X
    Topics: Geosciences
    Published by Oxford University Press on behalf of The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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  • 4
    Publication Date: 2013-09-28
    Description: Background: Two population surveys were conducted in Belarus: The Living Conditions, Lifestyle and Health (LLH) in 2001 ( n = 2000) and The Health in Times of Transition (HITT) in 2010 ( n = 1800). Each survey included a question on health status. The LLH questionnaire provided a 4-point Verbal Response Scale, but the HITT questionnaire used a 5-point scale. When translated into Russian, only two response categories of these scales had identical wording. These differences made a direct comparison of self-reported health status between 2001 and 2010 difficult. Methods: We conducted a Health Category Response Scale (HCRS) survey in 2010 ( n = 570) using a 100ths graduated Visual Analogue Scale (VAS) to understand how the response categories of different scales are perceived by Russian speakers. We implemented the HCRS survey’s data to calculate the weighted health status (WHS) for each of the original surveys and to compare health status in Belarus between 2001and 2010. Results: The WHS in Belarus showed a small, but statistically significant, improvement of 2.9 points on a 0–100 scale between 2001 and 2010 (56.2 vs. 59.1). Identical response categories were perceived differently on a 4-point and 5-point VAS. The category ‘good’ (‘opoee’) measured ~12 points higher, and the category ‘bad/poor’ (‘ooe’) measured ~16 points lower, on the 4-point compared with the 5-point VAS. Conclusion: Our HCRS survey and novel method enabled a direct comparison of questions with different response options. When applied to the LLH and HITT projects, we concluded that health status in Belarus has improved between 2001 and 2010.
    Print ISSN: 1101-1262
    Electronic ISSN: 1464-360X
    Topics: Medicine
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  • 5
    Publication Date: 2011-12-08
    Description: Smith, W. K., and Solow, A. R. 2012. Missing and presumed lost: extinction in the ocean and its inference. – ICES Journal of Marine Science, 69: 89–94. The number of modern extinctions in the ocean is unknown. The actual demise of the last individual of a species is essentially unobservable, so extinction can only be inferred. Statistical methods are described for inferring extinction from sighting records, species–area considerations, and taxonomic samples collected at two different times. The methods are illustrated using a variety of real datasets, including a sighting record of the Caribbean monk seal and results from three surveys of benthic invertebrates.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
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  • 6
    Publication Date: 2016-12-06
    Description: Aims The effects of clouds are now recognized as critically important to the understanding of climate change impacts on ecosystems. Regardless, few studies have focused specifically on the ecophysiological responses of plants to clouds. Most continental mountain ranges are characterized by common convective cloud formation in the afternoons, yet little is known regarding this influence on plant water and carbon relations. Here we compare the ecophysiology of two contrasting, yet ubiquitous growth forms, needle-leaf and broadleaf, under representative cloud regimes of the Snowy Range, Medicine Bow Mountains, southeastern Wyoming, USA. Methods Photosynthetic gas exchange, water use efficiency, xylem water potentials and micrometeorological data were measured on representative clear, overcast and partly cloudy days during the summers of 2012 and 2013 for two indigenous broadleaf ( Caltha leptosepala and Arnica parryi ) and two needle-leaf species ( Picea engelmannii and Abies lasiocarpa ) that co-occur contiguously. Important Findings Reductions in sunlight with cloud cover resulted in more dramatic declines in photosynthesis for the two broadleaf species (ca. 50–70% reduction) versus the two conifers (no significant difference). In addition, the presence of clouds corresponded with lower leaf conductance, transpiration and plant water status in all species. However, the more constant photosynthesis in conifers under all cloud conditions, coupled with reduced transpiration, resulted in greater water use efficiency (ca. 25% higher) than the broadleaf species. These differences appear to implicate the potential importance of natural cloud patterns in the adaptive ecophysiology of these two contrasting, but common, plant growth forms.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
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  • 7
    Publication Date: 2012-10-31
    Description: The taper equations used by the Ministry of Forests, Lands and Natural Resource Operations in British Columbia (BC), Canada, date back to the mid-1950s. Very little work has been done on examining the effect of climate on taper, particularly for BC but elsewhere as well. The objective of our research was to determine whether climate has an effect on tree taper for lodgepole pine ( Pinus contorta Dougl. ex Loud.) in BC. The data for this project consisted of multiple diameter inside bark measurements along the stems of 270 trees across eight biogeoclimatic zones. In addition, 20 climate variables for the sample sites were predicted from the ClimateWNA model. Kozak's variable-exponent taper model was refitted with the climate variables in the exponent of the model. The single temperature- and precipitation-related variables that provided the best fit were incorporated into the final taper model. The model was analysed as a mixed-effects model, with spatial correlation and heteroscedastic errors being explicitly modelled. Mean annual precipitation and the Julian date of the first frost after the summer growing period were the best predictors of taper. Further work is required to understand why these variables are important predictors of taper, but a possible linkage is through the tree's crown.
    Print ISSN: 0015-752X
    Electronic ISSN: 1464-3626
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 8
    Publication Date: 2012-09-21
    Description: In estimates of illness severity from the spring wave of the 2009 influenza A (H1N1) pandemic, reported case fatality proportions were less than 0.05%. In prior pandemics, subsequent waves of illness were associated with higher mortality. The authors evaluated the burden of the pandemic H1N1 (pH1N1) outbreak in metropolitan Atlanta, Georgia, in the fall of 2009, when increased influenza activity heralded the second wave of the pandemic in the United States. Using data from a community survey, existing surveillance systems, public health laboratories, and local hospitals, they estimated numbers of pH1N1-associated illnesses, emergency department (ED) visits, hospitalizations, intensive care unit (ICU) admissions, and deaths occurring in metropolitan Atlanta during the period August 16, 2009–September 26, 2009. The authors estimated 132,140 pediatric and 132,110 adult symptomatic cases of pH1N1 in metropolitan Atlanta during the investigation time frame. Among children, these cases were associated with 4,560 ED visits, 190 hospitalizations, 51 ICU admissions, and 4 deaths. Among adults, they were associated with 1,130 ED visits, 590 hospitalizations, 140 ICU admissions, and 63 deaths. The combined symptomatic case hospitalization proportion, case ICU admission proportion, and case fatality proportion were 0.281%, 0.069%, and 0.024%, respectively. Influenza burden can be estimated using existing data and local surveys. The increased severity reported for subsequent waves in past pandemics was not evident in this investigation. Nevertheless, the second pH1N1 pandemic wave led to substantial numbers of ED visits, hospitalizations, and deaths in metropolitan Atlanta.
    Print ISSN: 0002-9262
    Electronic ISSN: 1476-6256
    Topics: Medicine
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  • 9
    Publication Date: 2014-06-08
    Description: In cloud forests, foliar uptake (FU) of water has been reported for numerous species, possibly acting to relieve daily water and carbon stress. While the prevalence of FU seems common, how daily variation in fog timing may affect this process has not been studied. We examined the quantity of FU, water potentials, gas exchange and abiotic variation at the beginning and end of a 9-day exposure to fog in a glasshouse setting. Saplings of Abies fraseri (Pursh) Poir. and Picea rubens Sarg. were exposed to morning (MF), afternoon (AF) or evening fog (EF) regimes to assess the ability to utilize fog water at different times of day and after sustained exposure to simulated fog. The greatest amount of FU occurred during MF (up to 50%), followed by AF (up to 23%) and then EF, which surprisingly had no FU. There was also a positive relationship between leaf conductance and FU, suggesting a role of stomata in FU. Moreover, MF and AF lead to the greatest improvements in daily water balance and carbon gain, respectively. Foliar uptake was important for improving plant ecophysiology but was influenced by diurnal variation in fog. With climate change scenarios predicting changes to cloud patterns and frequency that will likely alter diurnal patterns, cloud forests that rely on this water subsidy could be affected.
    Print ISSN: 0829-318X
    Electronic ISSN: 1758-4469
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 10
    Publication Date: 2014-11-07
    Description: Mutations in the leucine-rich repeat kinase-2 ( LRRK2 ) gene cause autosomal-dominant Parkinson's disease (PD) and contribute to sporadic PD. LRRK2 contains Guanosine-5'-triphosphate (GTP) binding, GTPase and kinase activities that have been implicated in the neuronal degeneration of PD pathogenesis, making LRRK2, a potential drug target. To date, there is no disease-modifying drug to slow the neuronal degeneration of PD and no published LRRK2 GTP domain inhibitor. Here, the biological functions of two novel GTP-binding inhibitors of LRRK2 were examined in PD cell and mouse models. Through a combination of computer-aided drug design (CADD) and LRRK2 bio-functional screens, two novel compounds, 68 and 70 , were shown to reduce LRRK2 GTP binding and to inhibit LRRK2 kinase activity in vitro and in cultured cell assays. Moreover, these two compounds attenuated neuronal degeneration in human SH-SY5Y neuroblastoma cells and mouse primary neurons expressing mutant LRRK2 variants. Although both compounds inhibited LRRK2 kinase activity and reduced neuronal degeneration, solubility problems with 70 prevented further testing in mice. Thus, only 68 was tested in a LRRK2-based lipopolysaccharide (LPS)-induced pre-inflammatory mouse model. 68 reduced LRRK2 GTP-binding activity and kinase activity in brains of LRRK2 transgenic mice after intraperitoneal injection. Moreover, LPS induced LRRK2 upregulation and microglia activation in mouse brains. These findings suggest that disruption of GTP binding to LRRK2 represents a potential novel therapeutic approach for PD intervention and that these novel GTP-binding inhibitors provide both tools and lead compounds for future drug development.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
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