357 resultados para Calvin
Resumo:
Several studies have shown that successful Employee Assistance Programs (EAPs) have strong management endorsement. Strong management endorsement is defined as positive support in utilizing EAP services for themselves and their employees. This study focuses solely on middle management as opposed to upper or general management support. The study further examines success or lack of success of an EAP by the utilization rate defined as the number of employees over a year period who access EAP services.^ A analytical cross-sectional design was used to compare and observe differences between two groups of middle managers (utilizers and nonutilizers). Middle manager data was collected through a mail questionnaire. The study focused on identifying predictors that influence middle managers' utilization rate specifically: attitude toward EAPs, EAP knowledge level, attitude toward mental health professionals, age, gender, years worked as a middle manager, education level, training, and other possible predictors of utilization. The overall hypothesis states middle manager utilizers of EAP services have more positive attitudes and a better understanding of their EAP than middle management nonutilizers.^ As predicted, nonparametric bivariate results showed significant differences between the two groups. Middle managers in the utilization group (n = 473) tended to show more positive attitudes toward their EAP and mental health professionals and demonstrated greater EAP knowledge compared to the nonutilization group (n = 154). These findings support past studies on variables that influence EAP utilization rates.^ Further variables found to influence middle management utilization were identified by multivariate logistic regression results. These variable were gender (female supervisors), educational levels of employees supervised (employees with lower levels of education), number of employees supervised (greater the number supervised, more likely to utilize), managerial EAP training (trained supervisors) and awareness that problems do influence an employee's productivity.^ These findings strengthen the assertion that middle management's attitudes, as well as other variables may influence utilization. Study findings add new information about important variables specifically influencing middle management who utilize EAPs. An understanding of these variables is essential in developing competent EAP program training and orientation programs for middle managers. ^
Resumo:
Climate models predict more frequent and more severe extreme events (e.g., heat waves, extended drought periods, flooding) in many regions for the next decades. The impact of adverse environmental conditions on crop plants is ecologically and economically relevant. This review is focused on drought and heat effects on physiological status and productivity of agronomically important plants. Stomatal opening represents an important regulatory mechanism during drought and heat stress since it influences simultaneously water loss via transpiration and CO2 diffusion into the leaf apoplast which further is utilized in photosynthesis. Along with the reversible short-term control of stomatal opening, stomata and leaf epidermis may produce waxy deposits and irreversibly down-regulate the stomatal conductance and non-stomatal transpiration. As a consequence photosynthesis will be negatively affected. Rubisco activase—a key enzyme in keeping the Calvin cycle functional—is heat-sensitive and may become a limiting factor at elevated temperature. The accumulated reactive oxygen species (ROS) during stress represent an additional challenge under unfavorable conditions. Drought and heat cause accumulation of free amino acids which are partially converted into compatible solutes such as proline. This is accompanied by lower rates of both nitrate reduction and de novo amino acid biosynthesis. Protective proteins (e.g., dehydrins, chaperones, antioxidant enzymes or the key enzyme for proline biosynthesis) play an important role in leaves and may be present at higher levels under water deprivation or high temperatures. On the whole plant level, effects on long-distance translocation of solutes via xylem and phloem and on leaf senescence (e.g., anticipated, accelerated or delayed senescence) are important. The factors mentioned above are relevant for the overall performance of crops under drought and heat and must be considered for genotype selection and breeding programs.
Resumo:
Foliar samples were harvested from two oaks, a beech, and a yew at the same site in order to trace the development of the leaves over an entire vegetation season. Cellulose yield and stable isotopic compositions (δ13C, δ18O, and δD) were analyzed on leaf cellulose. All parameters unequivocally define a juvenile and a mature period in the foliar expansion of each species. The accompanying shifts of the δ13C-values are in agreement with the transition from remobilized carbohydrates (juvenile period), to current photosynthates (mature phase). While the opponent seasonal trends of δ18O of blade and vein cellulose are in perfect agreement with the state-of-art mechanistic understanding, the lack of this discrepancy for δD, documented for the first time, is unexpected. For example, the offset range of 18 permil (oak veins) to 57 permil (oak blades) in δD may represent a process driven shift from autotrophic to heterotrophic processes. The shared pattern between blade and vein found for both oak and beech suggests an overwhelming metabolic isotope effect on δD that might be accompanied by proton transfer linked to the Calvin-cycle. These results provide strong evidence that hydrogen and oxygen are under different biochemical controls even at the leaf level.
Resumo:
Abstract Global change is characterized by increased {CO2} concentration in the atmosphere, increasing average temperature and more frequent extreme events including drought periods, heat waves and flooding. Especially the impacts of drought and of elevated temperature on carbon assimilation are considered in this review. Effects of extreme events on the subcellular level as well as on the whole plant level may be reversible, partially reversible or irreversible. The photosynthetically active biomass depends on the number and the size of mature leaves and the photosynthetic activity in this biomass during stress and subsequent recovery phases. The total area of active leaves is determined by leaf expansion and senescence, while net photosynthesis per leaf area is primarily influenced by stomatal opening (stomatal conductance), mesophyll conductance, activity of the photosynthetic apparatus (light absorption and electron transport, activity of the Calvin cycle) and {CO2} release by decarboxylation reactions (photorespiration, dark respiration). Water status, stomatal opening and leaf temperature represent a "magic triangle" of three strongly interacting parameters. The response of stomata to altered environmental conditions is important for stomatal limitations. Rubisco protein is quite thermotolerant, but the enzyme becomes at elevated temperature more rapidly inactivated (decarbamylation, reversible effect) and must be reactivated by Rubisco activase (carbamylation of a lysine residue). Rubisco activase is present under two forms (encoded by separate genes or products of alternative splicing of the pre-mRNA from one gene) and is very thermosensitive. Rubisco activase was identified as a key protein for photosynthesis at elevated temperature (non-stomatal limitation). During a moderate heat stress Rubisco activase is reversibly inactivated, but during a more severe stress (higher temperature and/or longer exposure) the protein is irreversibly inactivated, insolubilized and finally degraded. On the level of the leaf, this loss of photosynthetic activity may still be reversible when new Rubisco activase is produced by protein synthesis. Rubisco activase as well as enzymes involved in the detoxification of reactive oxygen species or in osmoregulation are considered as important targets for breeding crop plants which are still productive under drought and/or at elevated leaf temperature in a changing climate.
Resumo:
Briefe zwischen Mitarbeitern des Instituts für Sozialforschung und Max Horkheimer, 1964-1973; 13 Briefe und Beilagen zwischen dem Verwaltungsleiter IfS Siegfried Geissler und Max Horkheimer, 1968-1973; 9 Briefe zwischen Klaus Körber (Institut für Sozialforschung) und Max Horkheimer, 1971-1973; 2 Briefe zwischen dem Professor Rudolf Gunzert und Max Horkheimer, 1972; 2 Briefe zwischen Dr. Joachim Bergmann (Institut für Sozialforschung) und Max Horkheimer, 1971; 2 Briefe zwischen dem Professor Gerhard Brandt und Max Horkheimer, 1971; 6 Briefe zwischen Herbert Ludwig (Institut für Sozialforschung) und Max Horkheimer, 1966-1967; 3 Briefe von Max Horkheimer an Professor Franz Böhm, 1966; Briefe zwischen den Mitarbeitern des Instituts für Sozialforschung und Max Horkheimer, 1955-1959; 4 Briefe von Jürgen Habermas an Max Horkheimer, Frankfurt, 1957-1959; 3 Briefe zwischen Christoph Oehler und Max Horkheimer, 1959; 13 Briefe zwischen Ludwig von Friedeburg und Max Horkheimer, 1955-1959; 1 Brief von Werner Wilkening an Max Horkheimer, 1958; 1 Brief von Gerhard Brandt an Max Horkheimer, 1958; 1 Brief von Max Horkheimer an den Dekan Helmut Viebrock, 1958; 2 Briefe von Egon Becker mit Helge Pross und Ludwig Friedeburg an Max Horkheimer, Frankfurt, 1958-1959; 2 Briefe von Helge Pross mit Egon Becker und Ludwig Friedeburg an Max Horkheimer, Frankfurt, 1958-1959; 1 Brief von Dieter Arenz an Max Horkheimer, Frankfurt, 1956; Briefe vom und an das Institut für Sozialforschung (Advisory Board of the Institute of Social Research), 1940-1947; Briefe und Briefentwürfe an und von Mitgliedern des Advisory Board betreffend die Zusendung von Max Horkheimer "Eclipse of Reason" und Karl August Wittvogel/Olga Lang, "Chinese Family and Society"; vom Institut für Sozialforschung, 1946-1947; 1 Brief von Edwin Borchard vom Institut für Sozialforschung, 1947; 1 Brief von Friedrich Pollock an Alfred E. Cohn, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Stephan Duggan, Los Angeles, 1947; 2 Briefe zwischen Lloyd K. Garrison und Friedrich. Pollock, 1947; 1 Brief von Friedrich Pollock an Calvin B. Hoover, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Philip C. Jessup, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Wesley C. Mitchell, Los Angeles, 1947; 1 Brief von Friedrich Pollock an William A. Neilson, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Frederick M. Padelford, Los Angeles, 1947; 1 Brief von Friedrich Pollock an Thorsten Sellin, Los Angeles, 1947; 3 Briefe zwischen John Whyte und Friedrich Pollock, 1947; 2 Briefe zwischen Louis Wirth und Friedrich Pollock, 1947; 1 Brief von Friedrich Pollock an Howard Woolston, Los Angeles, 1947; 1 Brief von George H. Sabine an das Institut für Sozialforschung, Ithaca, New York, 1946; Briefe und Briefentwürfe an und von Mitgliedern des Advisory Board betreffend den Druck eines neuen Briefkopfs des Instituts, 1940; 1 Brief von Leo Löwenthal, Pacific Palisades an Margot von Mendelssohn, 1942; 1 Brief von Leo Löwenthal an Margot von Mendelssohn, Pacific Palisades, 1942; 1 Brief von Max Horkheimer an K. Pilser, 1942; 2 Briefe zwischen Charles A. Beard und Max Horkheimer, 1940; 2 Briefe zwischen Edwin M. Borchard und Max Horkheimer, 1940; 3 Briefe zwischen Henry Sloane Coffin und Max Horkheimer, 1940; 2 Briefe zwischen Morris R. Cohen und Max Horkheimer, 1940; 2 Briefe zwischen Alfred E. Cohn und Max Horkheimer, 1940; 2 Briefe zwischen Stephen Duggan und Max Horkheimer, 1940; 2 Briefe zwischen dem Soziologen Henry Pratt Fairchild und Max Horkheimer, 1940; 2 Briefe zwischen Sidney B. Fay und Max Horkheimer, 1940; 2 Briefe zwischen Lloyd K. Garrison und Max Horkheimer, 1940; 1 Brief von Max Horkheimer an Calvin B. Hoover, 1940; 2 Briefe zwischen Robert M. Hutchins und Max Horkheimer, 1940; 2 Briefe zwischen Philip C. Jessup und Max Horkheimer, 1940; 2 Briefe zwischen Lewis L. Lorwin und Max Horkheimer, 1940; 2 Briefe zwischen Robert S. Lynd und Max Horkheimer, 1940; 2 Briefe zwischen Robert M. MacIver und Max Horkheimer, 1940; 2 Briefe von Max Horkheimer an Charles H. McIlwain, 1940; 2 Briefe zwischen Charles E. Merriam und Max Horkheimer, 1940; 2 Briefe zwischen Wesley C. Mitchell und Max Horkheimer, 1940; 2 Briefe zwischen William A. Nielson und Max Horkheimer, 1940; 5 Briefe zwischen Howard W. Odum und Max Horkheimer, 1940; 3 Briefe zwischen Frederick M. Padelford und Max Horkheimer, 1940; 3 Briefe von Max Horkheimer an Max Radin, 1940; 2 Briefe zwischen George H. Sabine und Max Horkheimer, 1940; 2 Briefe zwischen Thorsten Sellin und Max Horkheimer, 1940; 2 Briefe zwischen James T. Shotwell und Max Horkheimer, 1940; 1 Brief von dem Soziologen Louis Wirth an Franz Neumann, Chicago, 1940; 1 Brief von Louis Wirth an Franz L. Neumann, Chicago, 1940; 3 Briefe zwischen Howard Woolston und Max Horkheimer, 1940;
Resumo:
Neumann, Franz: Memorandum über Gespräche mit Harold Lasswell. 30.03.1941, Typoskript mit handschriftlichen Korekturen, 4 Blatt; Neumann, Franz: Memorandum über Gespräche mit Goodvin Watson. 21.05.1941, Typoskript, 2 Blatt; [Anderson, Eugene N.:] "Professor Anderson's Notes and criticisms to the project of German society and culture". Typoskript, 7 Blatt; "Budget for the proposed Research Project of Cultural Aspects of National Socialism". Handschriftliche Notizen, 1 Blatt; Institut of Social Research: Brief an Rockefeller Foundation, New York, 24.06.1941 verschiedene Typoskripte, zum Teil mit handschriftlichen Korrekturen, circa 35 Blatt; ein Manuskript, 6 Blatt; ein Entwurf, Typoskript, 1 Blatt; Adorno, Theodor W.: 2 Briefe an I. Berlin, ohne Ort, 1940-1941; Empfehlungsschreiben zur Unterstützung des Projekts, von: Lutz, Ralph H.: 1 Brief (Abschrift) an Frederick Pollock, 11.07.1941; MacIver, Robert M.: 1 Brief (Abschrift): an New York Foundation, ohne Ort, 07.07.1941; Shotwell, James T.: 1 Brief (Abschrift) an Frederick Pollock, Woodstock, 08.07.1941; Radin, MAx: 1 Brief (Abschrift) an New York Foundation, [Los Angeles], 08.07-1941; 5 Blatt; Antwortbriefe an das Institut bzw. Max Horkheimer aufgrund der Zusendung des Umrisses des Forschungsprojektes, von: Lorwin, Lewis L.; Wooleton, H.; O'Quin, Patricia, Odum, Howard W.; Fay, Sidney B.; Merriam, Charles E.; Hoover, Calvin B.; Garrison, Lloyd K.; März bis Mai 1941, 8 Blatt;
Resumo:
Modern microbial mats are widely recognized as useful analogs for the study of biogeochemical processes relevant to paleoenvironmental reconstruction in the Precambrian. We combined microscopic observations and investigations of biomarker composition to investigate community structure and function in the upper layers of a thick phototrophic microbial mat system from a hypersaline lake on Kiritimati (Christmas Island) in the Northern Line Islands, Republic of Kiribati. In particular, an exploratory incubation experiment with 13C-labeled bicarbonate was conducted to pinpoint biomarkers from organisms actively fixing carbon. A high relative abundance of the cyanobacterial taxa Aphanocapsa and Aphanothece was revealed by microscopic observation, and cyanobacterial fatty acids and hydrocarbons showed 13C-uptake in the labeling experiment. Microscopic observations also revealed purple sulfur bacteria (PSB) in the deeper layers. A cyclic C19:0 fatty acid and farnesol were attributed to this group that was also actively fixing carbon. Background isotopic values indicate Calvin-Benson cycle-based autotrophy for cycC19:0 and farnesol-producing PSBs. Biomarkers from sulfate-reducing bacteria (SRB) in the top layer of the mat and their 13C-uptake patterns indicated a close coupling between SRBs and cyanobacteria. Archaeol, possibly from methanogens, was detected in all layers and was especially abundant near the surface where it contained substantial amounts of 13C-label. Intact glycosidic tetraether lipids detected in the deepest layer indicated other archaea. Large amounts of ornithine and betaine bearing intact polar lipids could be an indicator of a phosphate-limited ecosystem, where organisms that are able to substitute these for phospholipids may have a competitive advantage.
Resumo:
Ocean acidification is expected to lower the net accretion of coral reefs yet little is known about its effect on coral photophysiology. This study investigated the effect of increasing CO2 on photosynthetic capacity and photoprotection in Acropora formosa. The photoprotective role of photorespiration within dinoflagellates (genus Symbiodinium) has largely been overlooked due to focus on the presence of a carbon-concentrating mechanism despite the evolutionary persistence of a Form II Rubisco. The photorespiratory fixation of oxygen produces phosphoglycolate that would otherwise inhibit carbon fixation though the Calvin cycle if it were not converted to glycolate by phosphoglycolate phosphatase (PGPase). Glycolate is then either excreted or dealt with by enzymes in the photorespiratory glycolate and/or glycerate pathways adding to the pool of carbon fixed in photosynthesis. We found that CO2 enrichment led to enhanced photoacclimation (increased chlorophyll a per cell) to the subsaturating light levels. Light-enhanced dark respiration per cell and xanthophyll de-epoxidation increased, with resultant decreases in photosynthetic capacity (Pnmax) per chlorophyll. The conservative CO2 emission scenario (A1B; 600-790 ppm) led to a 38% increase in the Pnmax per cell whereas the 'business-as-usual' scenario (A1F1; 1160-1500 ppm) led to a 45% reduction in PGPase expression and no change in Pnmax per cell. These findings support an important functional role for PGPase in dinoflagellates that is potentially compromised under CO2 enrichment.