850 research outputs found
Relating coccolithophore calcification rates to phytoplankton community dynamics: regional differences and implications for carbon export
No full textRecent measurements of surface coccolithophore calcification from the Atlantic Ocean (50°N–50°S) are compared to similar measurements from other oceanic settings. By combining the different data sets of surface measurements, we examine general and regional patterns of calcification relative to organic carbon production (photosynthesis) and other characteristics of the phytoplankton community. Generally, surface calcification and photosynthesis are positively correlated, although the strength of the relationship differs between biogeochemical provinces. Relationships between surface calcification, chlorophyll-a and calcite concentrations are also statistically significant, although again there is considerable regional variability. Such variability appears unrelated to phytoplankton community composition or hydrographic conditions, and may instead reflect variations in coccolithophore physiology. The contribution of inorganic carbon fixation (calcification) to total carbon fixation (calcification plus photosynthesis) is 1–10%, and we estimate a similar contribution from coccolithophores to total organic carbon fixation. However, these contributions vary between biogeochemical provinces, and occasionally coccolithophores may account for >20% of total carbon fixation in unproductive central subtropical gyres. Combining surface calcification and photosynthetic rates with standing stocks of calcite, particulate organic carbon, and estimated phytoplankton carbon allows us to examine the fates of these three carbon pools. The relative turnover times vary between different biogeochemical provinces, with no clear relationship to the overall productivity or phytoplankton community structure found in each province. Rather, interaction between coccolithophore physiology (coccolith production and detachment rates), species diversity (cell size), and food web dynamics (grazer ecology) may control the composition and turnover times of calcite particles in the upper ocean. <br/
Letter from Karl I. Zimmerman and T.R. Martinez to Toshiko Chuman
No full textA letter to Toshiko Chuman (nee Nakamura) from Karl I. Zimmerman, District Director of Immigration and Naturalization Service (INS) in Philadelphia, and T.R. Martinez, Acting Chief, Detention, Deportation and Parole Section. The letter regards his release from INS into the custody of her attorney, Wayne M. Collins.The Chuman (Hayao "Sam" and Toshiko) Papers documents the World War II experiences of Hayao "Sam" and Toshiko Chuman, who were Kibei Nisei born in the United States but grew up and completed school in Japan, and then returned to the U.S. prior to the war. It chronicles the Chuman's incarceration from the Santa Anita Assembly Center, through Jerome, Rohwer, Tule Lake camps, and the Santa Fe and Crystal City internment camps as well as their struggle for restoring their U.S. citizenships in the 1960s. The digital collection consists of mostly textual material, including correspondence, affidavits, incarceration camp records, lease agreements, financial documents, receipts, pamphlets, and booklets
Letter from Karl I. Zimmerman and T.R. Martinez to Hayao (Sam) Chuman
No full textA letter to Hayao (Sam) Chuman from Karl I. Zimmerman, District Director of Immigration and Naturalization Service (INS) in Philadelphia, and T.R. Martinez, Acting Chief, Detention, Deportation and Parole Section. The letter regards his release from INS into the custody of his attorney, Wayne M. Collins.The Chuman (Hayao "Sam" and Toshiko) Papers documents the World War II experiences of Hayao "Sam" and Toshiko Chuman, who were Kibei Nisei born in the United States but grew up and completed school in Japan, and then returned to the U.S. prior to the war. It chronicles the Chuman's incarceration from the Santa Anita Assembly Center, through Jerome, Rohwer, Tule Lake camps, and the Santa Fe and Crystal City internment camps as well as their struggle for restoring their U.S. citizenships in the 1960s. The digital collection consists of mostly textual material, including correspondence, affidavits, incarceration camp records, lease agreements, financial documents, receipts, pamphlets, and booklets
Phytoplankton mineralization in the tropical and subtropical Atlantic Ocean
No full textOrganic carbon fluxes to the deep ocean may be enhanced by association with ballast mineral material such as calcite and opal. We made simultaneous measurements of the upper ocean production of calcite (calcification), opal (silicification) and organic carbon (photosynthesis) at 14 stations between 42°S and 49°N in the Atlantic Ocean. These measurements confirm the light-dependency of calcification and photosynthesis, and the substrate dependency of silicification. We estimate that mineralizing phytoplankton represent ~5–20% of organic carbon fixation, with similar contributions from both coccolithophores and diatoms. Estimates of average turnover times for calcite and phytoplankton carbon are ~3 days, indicative of their relatively labile nature. By comparison, average turnover times for opal and particulate organic carbon are ~10 days. Rapid turnover of calcite suggests an important role for the plankton community in removing calcite from the upper ocean. Comparison of our surface production rates to sediment trap data confirms that ~70% of calcite is dissolved in the upper 2–3 km, and only a small proportion of total organic carbon (<2%) reaches the deep ocean
On the origins of Cyprideis torosa (Jones, 1850) and a short biography of Professor T.R. Jones
No full textThe original description and taxonomic attribution of Cyprideis torosa (Jones, 1850) is reviewed with reference to the type locality at Grays, Essex, SE England and several of the original specimens are re-illustrated. A short biography of its author, the geologist T.R. Jones, is provided
Season 10 Episode 11: Healthcare Around the World
No full textFans of U.S. health care reform point out that many other countries provide coverage for all their citizens, and no one files for bankruptcy due to medical bills. But how exactly do these countries do it? January Series guest & journalist T.R. Reid, author of The Healing of America: A Global Quest for Better, Cheaper, and Fairer Health Care, tells of his travels comparing systems around the world. Shirley Hoogstra hosts. Episode #1011
On the origins of Cyprideis torosa (Jones, 1850) and a short biography of Professor T.R. Jones
No full textThe original description and taxonomic attribution of Cyprideis torosa (Jones, 1850) is reviewed with reference to the type locality at Grays, Essex, SE England and several of the original specimens are re-illustrated. A short biography of its author, the geologist T.R. Jones, is provided
Phytoplankton carbon fixation, chlorophyll-biomass and diagnostic pigments in the Atlantic Ocean
No full textWe have made daily measurements of phytoplankton pigments, size-fractionated (<2 and >2-?m) carbon fixation and chlorophyll-a concentration during four Atlantic Meridional Transect (AMT) cruises in 2003–04. Surface rates of carbon fixation ranged from <0.2-mmol C m?3 d?1 in the subtropical gyres to 0.2–0.5-mmol C m?3 d?1 in the tropical equatorial Atlantic. Significant intercruise variability was restricted to the subtropical gyres, with higher chlorophyll-a concentrations and carbon fixation in the subsurface chlorophyll maximum during spring in either hemisphere. In surface waters, although picoplankton (<2-?m) represented the dominant fraction in terms of both carbon fixation (50–70%) and chlorophyll-a (80–90%), nanoplankton (>2-?m) contributions to total carbon fixation (30–50%) were higher than to total chlorophyll-a (10–20%). However, in the subsurface chlorophyll maximum picoplankton dominated both carbon fixation (70–90%) and chlorophyll-a (70–90%). Thus, in surface waters chlorophyll-normalised carbon fixation was 2–3 times higher for nanoplankton and differences in picoplankton and nanoplankton carbon to chlorophyll-a ratios may lead to either higher or similar growth rates. These low chlorophyll-normalised carbon fixation rates for picoplankton may also reflect losses of fixed carbon (cell leakage or respiration), decreases in photosynthetic efficiency, grazing losses during the incubations, or some combination of all these. Comparison of nitrate concentrations in the subsurface chlorophyll maximum with estimates of those required to support the observed rates of carbon fixation (assuming Redfield stoichiometry) indicate that primary production in the chlorophyll maximum may be light rather than nutrient limited. <br/
Gender dynamics in data collection on reproductive health: field experiences in Kerala, India
No full textReproductive health researchers tend to choose interviewers of the same sex as those interviewed. In many societies, it is considered unacceptable for men to interview women on topics of an intensely personal nature like sexuality or contraceptive use. In this paper, the author analyzes 21 interviews and 16 focus group discussions (FGDs) undertaken during a field study on the Quality of Services in the Indian Family Welfare Programs conducted in Kerala. The analysis was based on the model which identifies the principal participants in the interview as the respondent and the interviewer. In all these cases the contradiction between the gendered roles of the interviewer and interviewee are visible. However, if viewed in the context of the model provided by Briggs, it is clear that these contradictions are due to the differences in the social roles that the interviewers assumed and that the respondents ascribed to them and in the interactional goals of the interviewers and the respondents. Contradictions were also experienced during the FGDs. Educational sessions on contraception are a good tool for gathering sensitive information instead of the conventional interview, where the gendered roles are so crucial to the information gathering exercise itself
Klastische en kataklastische processen en hun betekenis voor de gesteentemechanica: Inleiding tot een breukmechanica voor gesteente
No full textCivil Engineering and Geoscience
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