4,321 research outputs found

    Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica

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    The bioavailability of iron influences the distribution, biomass and pioductivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (\u3e24 h) and short-term (24 h) iron-addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (sigma(rpsII)) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplanlcton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea

    Village and household economics in India's semi-arid tropics

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    The book, based on unique source of information: household panel data from longitudinal village studies that had been carried out since 1975 in two villages in each of the selected three districts of India, is divided in to four parts. How the village studies were conducted and how they fit into social and agricultural research in India are discussed in chapter 2. Profiles of the study regions and villages are presented in chapter 3. Agricultural and economic development in these study villages since independence and particularly in the period 1975 to 1985 is treated in part 2. Part 3 makes more integrated microeconomic treatment of agricultural development in predominantly dryland production environments. The implications of these findings are drawn out in a concluding session of each subject matter chapter and. In a final synthesis chapter, the particular features of India''s SAT are reviewed and prospects for agricultural development assesse

    Low State, Phase-Resolved IR Spectroscopy of VV Puppis

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    We present phase-resolved low resolution JHKJHK and higher resolution KK-band spectroscopy of the polar VV Pup. All observations were obtained when VV Pup was in a low accretion state having a K magnitude near 15. The low resolution observations reveal cyclotron emission in the JJ band during some phases, consistent with an origin near the active 30.5 MG pole on the white dwarf. The secondary in VV Pup appears to be a normal M7V star and we find that the HH and KK band fluxes are entirely due to this star at all orbital phases during the low accretion state. We use our higher resolution Keck spectroscopy to produce the first KK-band radial velocity curve for VV Pup. Our orbital solution yields K2K_2=414±27\pm27 km sec1^{-1} and leads to mass estimates of M1_1=0.73±\pm0.05 M_{\odot} and M2_2=0.10±\pm0.02 M_{\odot}. We find that the mass accretion rates during the normal low states of the polars VV Pup, EF Eri, and EQ Cet are near 1013^{-13} M_{\odot} yr1^{-1}. The fact that \.M is not zero in low state polars indicates active secondary stars in these binary systems, including the sub-stellar donor star present in EF Eri.Comment: Accepted in Astronomical Journal 5 figure

    Language Growth in Children with Mild to Severe Hearing Loss who Received Early Intervention by 3 Months or 6 Months of Age

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    Purpose: To evaluate the impact of hearing screening, diagnosis, and early intervention (EI) by 3 months or 6 months of age on language growth trajectories for children with hearing loss (HL) relative to children with normal hearing (NH). Method: We recruited 133 children with mild to severe HL through universal newborn hearing screening records and referrals from audiologists in the United States; 116 children with NH who served as a comparison group. Examiners administered a battery of developmentally appropriate language measures between 12 months and 8 years of age. We constructed latent growth curve models of global language, grammar, and vocabulary using Bayesian statistics. Results: Children with HL demonstrated no significant differences in initial language skills compared to children with NH. Children in the 1-3-6 group also showed no difference in language growth compared to children with NH. The slope for the 1-2-3 group was significantly steeper than children with NH for global language and grammar. Conclusions: This study documents the positive impact of EI on language outcomes in children with congenital HL. It is among the first to provide evidence to support the potential effects of very early intervention by 3 months of age

    Smoke-Free Policy in Vermont Public Housing Authorities

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    Introduction. Millions of adults and children living in public housing face exposure to second hand smoke from adjacent apartments. These tenants are less able to escape smoke exposure by moving, and Housing Authorities are beginning to implement smoke-free policies. We assessed the status of smoke-free policy in Vermont public housing, and explored the experience of tenants and managers in Burlington who recently implemented such a policy.https://scholarworks.uvm.edu/comphp_gallery/1080/thumbnail.jp

    Temporal progression of photosynthetic-strategy in phytoplankton in the Ross Sea, Antarctica

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    Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 166 (2017): 87-96, doi:10.1016/j.jmarsys.2016.08.014.The bioavailability of iron influences the distribution, biomass and productivity of phytoplankton in the Ross Sea, one of the most productive regions in the Southern Ocean. We mapped the spatial and temporal extent and severity of iron-limitation of the native phytoplankton assemblage using long- (>24 h) and short-term (24 h) iron- addition experiments along with physiological and molecular characterisations during a cruise to the Ross Sea in December-February 2012. Phytoplankton increased their photosynthetic efficiency in response to iron addition, suggesting proximal iron limitation throughout most of the Ross Sea during summer. Molecular and physiological data further indicate that as nitrate is removed from the surface ocean the phytoplankton community transitions to one displaying an iron-efficient photosynthetic strategy characterised by an increase in the size of photosystem II (PSII) photochemical cross section (σPSII) and a decrease in the chlorophyll-normalised PSII abundance. These results suggest that phytoplankton with the ability to reduce their photosynthetic iron requirements are selected as the growing season progresses, which may drive the well-documented progression from Phaeocystis antarctica- assemblages to diatom-dominated phytoplankton. Such a shift in the assemblage-level photosynthetic strategy potentially mediates further drawdown of nitrate following the development of iron deficient conditions in the Ross Sea.This research was supported by grants from the National Science Foundation (ANT-0944254 to W.O.S., ANT-0944174 to P.N.S.), and a NERC PhD studentship to TRK

    Protecting children: the central role of knowledge

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    Following the deaths of Victoria Climbié and of Peter Connelly (Baby P) the media has raged about social work competence, the public have expressed dismay and the government has responded with proposals designed to alter practice procedures. Altering procedures gives the appearance of change without necessarily improving practice. Do social workers have sufficient knowledge to make the decisions that they are responsible for? This paper examines whether a restricted knowledge base contributes to social workers missing or misjudging signs of maltreatment. The paper also looks at evidence suggesting that social workers are resistant to developing new ways of working. A more positive approach to developing expert knowledge and engagement with the inter-professional knowledge base is proposed
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