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Major Shift (major + shift)
Selected AbstractsDocumenting Loss of Large Trophy Fish from the Florida Keys with Historical PhotographsCONSERVATION BIOLOGY, Issue 3 2009LOREN McCLENACHAN arrecifes de coral; ecología histórica; directrices cambiantes; peces de arrecife; sobrepesca Abstract:,A loss of large vertebrates has occurred in aquatic and terrestrial ecosystems, but data to measure long-term population changes are sparse. Historical photographs provide visual and quantitative evidence of changes in mean individual size and species composition for groups of marine fish that have been targeted by sport fishing. I measured such trends for 13 groups of recreationally caught "trophy" reef fish with photographs taken in Key West, Florida, from 1956 to 2007. The mean fish size declined from an estimated 19.9 kg (SE 1.5) to 2.3 kg (SE 0.3), and there was a major shift in species composition. Landings from 1956 to 1960 were dominated by large groupers (Epinephelus spp.), and other large predatory fish were commonly caught, including sharks with an average length of just <2 m. In contrast, landings in 2007 were composed of small snappers (Lutjanus spp. and Ocyurus chrysurus) with an average length of 34.4 cm (SE 0.62), and the average length of sharks declined by more than 50% over 50 years. Major declines in the size of fish caught were not reflected in the price of fishing trips, so customers paid the same amount for a less-valuable product. Historical photographs provide a window into a more pristine coral reef ecosystem that existed a half a century ago and lend support to current observations that unfished reef communities are able to support large numbers of large-bodied fish. Resumen:,Una pérdida de vertebrados mayores ha ocurrido en ecosistemas acuáticos y terrestres, pero los datos para medir los cambios poblaciones a largo plazo son escasos. Las fotografías históricas proporcionan evidencia visual y cuantitativa de cambios en el tamaño individual promedio y de la composición de especies en grupos de peces marinos que han sido blanco de la pesca deportiva. Medí esas tendencias en 13 grupos de peces de arrecife capturados recreativamente como "trofeos" mediante fotografías tomadas en Key West, Florida, desde 1956 a 2007. El peso promedio de los peces declinó de unos 19.9 kg (ES 1.5) a 2.3 kg (ES 0.3), y hubo un cambio mayor en la composición de especies. Las capturas entre 1956 y 1960 estuvieron dominadas por meros (Epinephelus spp.) grandes, y otros peces depredadores eran capturados comúnmente, incluyendo tiburones con una longitud promedio de poco menos de 2m. En contraste, las capturas en 2007 fueron compuestas de pargos (Lutjanus spp. y Ocyurus chrysurus) pequeños con una longitud promedio de 34.4 cm (ES 0.62), y la longitud promedio de los tiburones declinó más de 50% en 50 años. La gran declinación en el tamaño de los peces capturados no se reflejó en los precios de los viajes de pesca, así que los clientes pagaron la misma cantidad por un producto menos valioso. Las fotografías históricas proporcionan una visión de un ecosistema arrecifal coralino prístino que existió hace medio siglo y proporcionan soporte a los comentarios actuales de que las comunidades arrecifales no explotadas son capaces de soportar numerosos peces de talla grande. [source] Climatic influence on the inter-annual variability of late-Holocene minerogenic sediment supply in a boreal forest catchmentEARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2010Gunilla Petterson Abstract Processes controlling sediment yield vary over a range of timescales, although most process-based observations are extremely short. Lake sediments, however, can be used to extend the observational timescale and are particularly useful when annually laminated (varved) sediment is present. The sediment record at Kassjön (N. Sweden) consists of ,6400 varves, each 0·5,1 mm thick. Image analysis was used to determine grey-scale variation and varve thickness from which annual minerogenic accumulation rate (MinAR) (mg cm,2 year,1) was inferred for the period 4486 BC , AD 1900. MinAR varies on annual to centennial scales and mainly reflects channel bank erosion by the inflow streams. The mineral input reflects the intensity of the spring run-off, which is dependent on the amount of snow accumulated during the winter, and hence MinAR is a long-term record of variability in past winter climate; other factors will be a variable response to catchment uplift, vegetation succession and pedogenesis. A major shift from low to high MinAR occurred ,250 BC, and peaks occurred around AD 250, 600, 1000, 1350 and 1650. Wavelet power spectrum analysis (confirmed by Fourier analyses) indicated significantly different periodicities throughout the period 4000 BC , AD 1700, including 275 years for the period 4000 BC , 2900 BC, 567 years for the period 2901 BC , 1201 BC, and 350 and 725 years for the period 1200 BC , AD 1700. The long-term, centennial scale variability (,350 years) may reflect solar forcing (cf the 385-year peak in tree-ring calibrated 14C activity) but interestingly, there is no obvious link to high frequency forcing, such as the North Atlantic Oscillation. The high resolution component of the record highlights the relevance of varved lake sediment records for understanding erosion dynamics in undisturbed forested catchments and their link to long-term climate dynamics and future climate change. Copyright © 2010 John Wiley & Sons, Ltd. [source] Abrupt community change on a rocky shore , biological mechanisms contributing to the potential formation of an alternative stateECOLOGY LETTERS, Issue 6 2004Robert T. Paine Abstract The 1997/1998 El Niño initiated a major shift in the intertidal assemblage on the Washington State outer coast. A 25 year time series (1978,2003) shows stands of dominant canopy algae replaced by mussel beds. A prior experiment had indicated that mussels can become too large to be eaten by starfish; newly initiated starfish removals predict mussel attainment of a size refuge. Such escapes inhibit recovery towards prior community composition and enhance development of alternative community states which may persist long after the originating forcing has lessened or disappeared. [source] Phosphorus decrease and climate variability: mediators of synchrony in phytoplankton changes among European peri-alpine lakesFRESHWATER BIOLOGY, Issue 10 2005ORLANE ANNEVILLE Summary 1. In an attempt to discern long-term regional patterns in phytoplankton community composition we analysed data from five deep peri-alpine lake basins that have been included in long-term monitoring programmes since the beginning of the 1970s. Local management measures have led to synchronous declines in phosphorus concentrations by more than 50% in all four lakes. Their trophic state now ranges from mesotrophic to oligotrophic. 2. No coherence in phytoplankton biomass was observed among lakes, or any significant decrease in response to phosphorus (P)-reduction (oligotrophication), except in Lakes Constance and Walen. 3. Multivariate analyses identified long-term changes in phytoplankton composition, which occurred coherently in all lakes despite the differing absolute phosphorus concentrations. 4. In all lakes, the phytoplankton species benefiting from oligotrophication included mixotrophic species and/or species indicative of oligo-mesotrophic conditions. 5. A major change in community composition occurred in all lakes at the end of the 1980s. During this period there was also a major shift in climatic conditions during winter and early spring, suggesting an impact of climatic factors. 6. Our results provide evidence that synchronous long-term changes in geographically separated phytoplankton communities may occur even when overall biomass changes are not synchronous. [source] Capital One banks on Six Sigma for strategy execution and culture transformationGLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 6 2007Aravind Immaneni When a major shift in strategy propelled Capital One Direct Banking business in a new direction, the organization,arming itself with Six Sigma expertise and capabilities,set out to change its management model, redesign its major business processes, and nurture a culture centered around customer focus and continuous improvement. Three years later, the associates have embraced this new culture of customer focus and a commitment to continuous improvement,all with enviable results to the bottom line. The Direct Banking business has been recognized both internally within Capital One and by external organizations with numerous awards for accomplishing this impressive cultural transformation. © 2007 Wiley Periodicals, Inc. [source] Junior doctors' working hours: Perspectives on the reformsINTERNATIONAL JOURNAL OF NURSING PRACTICE, Issue 3 2008Carol Wilkinson MSc BA(Hons) RGN Teacher's Cert Fellow Higher Education AcademyArticle first published online: 5 MAY 200 The European Working Time Directive for junior doctors came into force in Britain in August 2004. The reforms themselves have been a long time in development and implementation since the inception and debates regarding the New Deal, to the current formations under health and safety legislation. This study, undertaken within a hospital trust setting in England, provides an insight into the perspectives of doctors, nurses and human resources managers in relation to the European Working Time Directive. Critical consideration is given to the impact of the reforms upon the National Health Service and more specifically to daily working relationships at the point of implementation. The results demonstrate some ambivalence towards the reforms because of the major shift in culture for the professions per se, but also for the future of health-care delivery where there are considerable tensions. [source] Transnational Networks and Policy Diffusion: The Case of Gender MainstreamingINTERNATIONAL STUDIES QUARTERLY, Issue 1 2001Jacqui True How can we account for the global diffusion of remarkably similar policy innovations across widely differing nation-states? In an era characterized by heightened globalization and increasingly radical state restructuring, this question has become especially acute. Scholars of international relations offer a number of theoretical explanations for the cross-national convergence of ideas, institutions, and interests. We examine the proliferation of state bureaucracies for gender mainstreaming. These organizations seek to integrate a gender-equality perspective across all areas of government policy. Although they so far have received scant attention outside of feminist policy circles, these mainstreaming bureaucracies,now in place in over 100 countries,represent a powerful challenge to business-as-usual politics and policymaking. As a policy innovation, the speed with which these institutional mechanisms have been adopted by the majority of national governments is unprecedented. We argue that transnational networks composed largely of nonstate actors (notably women's international nongovernmental organizations and the United Nations) have been the primary forces driving the diffusion of gender mainstreaming. In an event history analysis of 157 nation-states from 1975 to 1998, we assess how various national and transnational factors have affected the timing and the type of the institutional changes these states have made. Our findings support the claim that the diffusion of gender-mainstreaming mechanisms has been facilitated by the role played by transnational networks, in particular by the transnational feminist movement. Further, they suggest a major shift in the nature and the locus of global politics and national policymaking. [source] Victims' Rights in Criminal Trials: Prospects for ParticipationJOURNAL OF LAW AND SOCIETY, Issue 2 2005Jonathan Doak Victims in common law jurisdictions have traditionally been unable to participate in criminal trials for a number of structural and normative reasons. They are widely perceived as ,private parties' whose role should be confined to that of witnesses, and participatory rights for such third parties are rejected as a threat to the objective and public nature of the criminal justice system. However, recent years have witnessed both a major shift in attitude in relation to the role of victims within the criminal justice system and a breakdown in the public/ private divide in criminal justice discourse. This article considers the standing of the victim within the criminal trial against the backdrop of such changes, and examines the arguments for a more radical course of reform that would allow victims to participate actively in criminal hearings as they are able to do in many European jurisdictions. [source] The Repoliticization of Collective Action After Neoliberalism in PeruLATIN AMERICAN POLITICS AND SOCIETY, Issue 3 2008Moisés Arce ABSTRACT Examining the popular uprising against the privatization of electric service in Arequipa and other revolts against foreign direct investment in Peru, this article explores the changing basis of antigovernment mobilizations against economic liberalization. It suggests that the transition from Fujimori to Toledo led to a major shift in the political opportunity structure, creating a more conducive environment for greater levels of mobilization while increasing the leverage of challengers, along with their chances to achieve positive goals. These new forms of collective resistance are geographically segmented or territorialized; they present concrete demands; and they often involve unexpected actors, yet they resonate at the national level. These results confirm the expectations from recent repoliticization literature insofar as collective actors remain acutely responsive to market reforms in more democratic settings. [source] Perspektiven der Alterssicherungspolitik in Deutschland ,Über Konzeptionen, Vorschläge und einen angestrebten ParadigmenwechselPERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 4 2000Winfried Schmähl The paper outlines different concepts for designing pension policies linked to current reform proposals in Germany. The role of the state, mandatory or voluntary savings for old age and the primary objectives and types of income redistribution aimed at by the design of pension schemes are central. In contrast to the economic debate which is dominated by the topic pay-as-you-go (PAYG) versus funding, the author argues that it is especially important to deal with changes within the major German PAYG-financed scheme in order to realize positive economic and social effects, especially by a close contribution??benefit link as part of a broader reform concept. There are, however, limits to an overall reduction of the pension level in such a pension scheme, if a close contribution??benefit link is to remain politically acceptable. Here this is demonstrated by current reform proposals for substituting a major part of PAYG pensions by funded pensions in Germany. The paper also points out some hidden, implicit and long-term effects of such a strategy. Finally, the author refers to some often neglected effects in mainstream proposals for a major shift towards funding. [source] Genetic continuity after the collapse of the Wari empire: Mitochondrial DNA profiles from Wari and post-Wari populations in the ancient AndesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Brian M. Kemp Abstract The Wari empire flourished in the central, highland Peruvian Andes from AD 600,1000, and although the events that led to its demise are unknown, archaeological evidence indicates that Wari control waned at the end of the first millennium. Here, we test the hypothesis that, despite the major shift in social and political organization at the fall of the Wari empire, the mitochondrial DNA (mtDNA) composition of populations from the Ayacucho Basin, the former imperial heartland of the empire, remained essentially unchanged. Results show that mtDNA haplogroup frequencies among the Wari and post-Wari groups differ, but the difference is not statistically significant (,2 = 5.886, df = 3, P = 0.1172). This is the first study in the Andes to use haplotypic data to evaluate the observed genetic distance between two temporally distinct prehispanic populations (FST = 0.029) against modeled expectations of four possible evolutionary scenarios. None of these simulations allowed the rejection of continuity. In total, at both the haplogroup and haplotype levels these data do not allow us to reject the hypothesis that post-Wari individuals sampled in this study are the maternal descendants of those sampled from the Wari era site of Conchopata. However, genetic homogeneity in the mitochondrial gene pool, as seen in the late prehispanic southern Andes, may also characterize our study region. But, prior to this research, this was unknown. If our new data show mtDNA homogeneity, then this could limit the detection of female migration if, in fact, it occurred. Nonetheless, the novel mtDNA data presented here currently do not support the hypothesis that there was an influx of genetically distinct females into the former Wari heartland after the Wari collapse. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] P450-catalyzed vs. electrochemical oxidation of haloperidol studied by ultra-performance liquid chromatography/electrospray ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2010Tove Johansson Mali'n The metabolites formed via the major metabolic pathways of haloperidol in liver microsomes, N -dealkylation and ring oxidation to the pyridinium species, were produced by electrochemical oxidation and characterized by ultra-performance liquid chromatography/electrospray ionization mass spectrometry (UPLC/ESI-MS). Liver microsomal incubations and electrochemical oxidation in the presence of potassium cyanide (KCN) resulted in two diastereomeric cyano adducts, proposed to be generated from trapping of the endocyclic iminium species of haloperidol. Electrochemical oxidation of haloperidol in the presence of KCN gave a third isomeric cyano adduct, resulting from trapping of the exocyclic iminium species of haloperidol. In the electrochemical experiments, addition of KCN almost completely blocked the formation of the major oxidation products, namely the N -dealkylated products, the pyridinium species and a putative lactam. This major shift in product formation by electrochemical oxidation was not observed for the liver microsomal incubations where the N -dealkylation and the pyridinium species were the major metabolites also in the presence of KCN. The previously not observed dihydropyridinium species of haloperidol was detected in the samples, both from electrochemical oxidation and the liver microsomal incubations, in the presence of KCN. The presence of the dihydropyridinium species and the absence of the corresponding cyano adduct lead to the speculation that an unstable cyano adduct was formed, but that cyanide was eliminated to regenerate the stable conjugated system. The formation of the exocyclic cyano adduct in the electrochemical experiments but not in the liver microsomal incubations suggests that the exocyclic iminium intermediate, obligatory in the electrochemically mediated N -dealkylation, may not be formed in the P450-catalyzed reaction. Copyright © 2010 John Wiley & Sons, Ltd. [source] Graduate density, gender, and employmentTHE BRITISH JOURNAL OF SOCIOLOGY, Issue 3 2002Malcolm Brynin ABSTRACT The expansion of higher education is often viewed as reflecting increased demand for skills, whether related to technological change or the growing complexity of the economy. It is also linked to widening pay differentials between the poorly and highly educated. There are reasons, however, to question these associations. Even if demand for graduates is growing the supply of graduates might as a result of the status derived from having a degree still exceed this. The demand for graduates itself need not be wholly tied in with upgrading of the labour force. Graduates could be part of a more flexible workforce who increasingly undertake non-graduate work, thus downgrading their labour-market position. LFS (Labour Force Survey) and BHPS (British Household Panel Study) data are used to show that there has been no major shift in the distribution of graduates in the British labour market, that career starts are increasingly at a lower status point, and that there is a negative effect of graduate density on wages. There are also redistributional effects. There has been a large increase in the social demand for higher education by women, and they have gained from this expansion while men have lost out. In addition, graduate density is positive for non-graduates, who gain from the reduced rewards accruing to graduates. The results call into question the simple idea of a trend towards a demand for increasing levels of skills and qualifications. More attention should be paid to the distribution of skills and to complex interactions within this. [source] Historical shrub,grass transitions in the northern Chihuahuan Desert: modeling the effects of shifting rainfall seasonality and event size over a landscape gradientGLOBAL CHANGE BIOLOGY, Issue 10 2003Qiong Gao Abstract We use a spatially explicit landscape model to investigate the potential role of rainfall on shrub,grass transitions in the Jornada Basin of southern New Mexico during the past century. In long-term simulations (1915,1998) along a 2700 m transect running from a dry lake bed to the foothills of a small mountain, we test two hypotheses: (i) that wetter winters and drier summers may have facilitated shrub encroachment in grasslands, and (ii) that increases in large precipitation events may have increased soil water recharge at deeper layers, thus favoring shrub establishment and growth. Our model simulations generally support the hypothesis that wetter winters and drier summers may have played a key role, but we are unable to reproduce the major shifts from grass- to shrub-domination that occurred in this landscape during the early part of the 1900s; furthermore, the positive shrub response to wetter winters and drier summers was only realized subsequent to the drought of 1951,1956, which was a relatively short ,window of opportunity' for increased shrub establishment and growth. Our simulations also generally support the hypothesis that an increase in the number of large precipitation events may also have favored shrub establishment and growth, although these results are equivocal, depending upon what constitutes a ,large' event and the timing of such events. We found complex interactions among (i) the amount/seasonality of rainfall, (ii) its redistribution in the landscape via run-on and runoff, (iii) the depth of the soil water recharge, and (iv) subsequent water availability for the growth and reproduction of shrubs vs. herbaceous plants at various landscape positions. Our results suggest that only a mechanistic understanding of these interactions, plus the role of domestic cattle grazing, will enable us to elucidate fully the relative importance of biotic vs. abiotic factors in vegetation dynamics in this semiarid landscape. [source] How work-place conditions, environmental toxicants and lifestyle affect male reproductive function,INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 5 2002Jens Peter Bonde Summary Major temporal and geographical shifts in male reproductive function is presently an issue worldwide. The hormonal disruption hypothesis has achieved considerable attention but epidemiological evidence in support of the theory is lacking. Several occupational hazards to male reproductive function are known but exposure prevalences are hardly sufficient to play a role for reduced sperm count in the general male population. Sedentary work may be an exception. Perhaps prolonged time in the sedentary position exhausts the testicular heat regulation. But so far studies addressing implications of the heat hypothesis in the general population are few. Neither change of sexual behaviour nor reduced period of sexual continence seems to be a likely explanation. Tobacco smoking and consumption of caffeine and alcoholic beverages in adulthood have a rather marginal impact on spermatogenesis and can hardly explain major shifts or regional differences in male reproductive health. However, prenatal effects following smoking during pregnancy might play a role because we have witnessed a smoking epidemic among fertile women in some countries during the second half of the twentieth century. Moreover, if genetic factors play more than a marginal role for testicular function and sperm count, pregnancy planning resulting in reduced family size during the past 100 years could possibly explain a decline in semen quality because the most fertile part of the population reproduce less while the subfertile probably continue to get a limited number of children. [source] Which demographic traits determine population growth in the invasive brown seaweed Sargassum muticum?JOURNAL OF ECOLOGY, Issue 4 2009Aschwin Engelen Summary 1Life-history traits commonly associated with plant invasiveness are vegetative reproduction or r -selected traits such as short generation times and high rates of reproduction and individual growth. 2We used matrix modelling to assess which demographic traits are important for the population growth of an invasive seaweed lacking vegetative reproduction and whether demographic and life-history strategies shift with increased dominance of the invader. The vital rates of one of the most successful invading seaweeds, Sargassum muticum, were investigated monthly for 2 years in intertidal pools dominated by the native brown seaweed Cystoseira humilis and by S. muticum, respectively. In order to speculate about the demographic mechanisms that determine invasiveness of S. muticum, and as the study sites were recently colonized, we assumed that C. humilis and S. muticum pools are proxies for early and late phases of invasion, respectively. 3Both deterministic and stochastic matrix models showed positive rates of population growth, and rates were significantly higher in the pools dominated by S. muticum than in the ones dominated by C. humilis, indicating demographic changes with invader dominance. The variability of population growth rates and of reproductive and elasticity values of S. muticum was higher in the pools dominated by C. humilis, suggesting invader-driven stabilization of environmental conditions. Generation times of the species increased with invader dominance, supporting invader-stabilized environmental conditions. 4Elasticity analyses revealed that the most important demographic trait for population growth rate at both levels of invader dominance was the persistence of the non-fertile adult fronds rather than reproduction or growth. No major shifts in the life-history strategy of S. muticum between levels of invader dominance were detected. 5Synthesis. This study suggests that the invasiveness of S. muticum, a perennial invader without vegetative reproduction, relies on K - rather than r -selected traits and without drastic changes in life-history strategy between phases of invasion. [source] Change over 70 years in a southern California chaparral community related to fire historyJOURNAL OF VEGETATION SCIENCE, Issue 5 2004Janet Franklin Abstract: Question: What changes in species composition and cover have occurred in chaparral as a function of fire history across an ecoregion? Location: San Diego County, California, USA. Methods: Stands in which 40 mid-elevation chaparral vegetation plots (each 400 m2 in area) were located in the 1930s were resurveyed in 2001. We stratified the stands into Infrequently versus Frequently burned (0,1 versus 2 or more fires recorded in the 91-yr period), and Immature versus Mature (31 yr versus >31 yr since last fire), resulting in four groups. Ten stands were randomly selected from each of these groups for survey. Results: There were no major shifts in life form composition, e.g., live oak trees were not invading chaparral that had experienced little or no fire, nor were subshrubs or herbaceous species replacing shrubs in areas that had experienced more frequent fires. However, there was a notable increase in the frequency of the subshrub Eriogonum fasciculatum across all fire history groups. In the mature stands with infrequent fire, average cover of resprouting shrubs increased (from 72 to 91%) and cover of obligate seeding shrubs (species with fire-cued germination) decreased (from 21 to 6%) significantly. Mature stands with frequent fire showed a significant decrease in resprouter cover (from 87 to 80%) and increase in obligate seeders (from 10 to 16%). Conclusions: While the tremendous changes in land use in southern California have been predicted to cause shifts in chaparral composition, these shifts are difficult to detect because species longevity and fire cycles are on the order of decades to a century. In this study, the expected trends could only be detected in groups that were mature at the time of the second survey. [source] Altered metabolic fluxes result from shifts in metabolite levels in sucrose phosphorylase-expressing potato tubersPLANT CELL & ENVIRONMENT, Issue 10 2002A. R. Fernie Abstract As reported in a previous paper (Plant, Cell and Environment 24, 357,365, 2001), introduction of sucrose phosphorylase into the cytosol of potato results in increased respiration, an inhibition of starch accumulation and decreased tuber yield. Herein a more detailed investigation into the effect of sucrose phosphorylase expression on tuber metabolism, in order to understand why storage and growth are impaired is described. (1) Although the activity of the introduced sucrose phosphorylase was low and accounted for less than 10% of that of sucrose synthase its expression led to a decrease in the activities of enzymes of starch synthesis relative to enzymes of glycolysis and relative to total amylolytic activity. (2) Incubation of tuber discs in [14C]glucose revealed that the transformants display a two-fold increase of the unidirectional rate of sucrose breakdown. However this was largely compensated by a large stimulation of sucrose re-synthesis and therefore the net rate of sucrose breakdown was not greatly affected. Despite this fact major shifts in tuber metabolism, including depletion of sucrose to very low levels, higher rates of glycolysis, and larger pools of amino acids were observed in these lines. (3) Expression of sucrose phosphorylase led to a decrease of the cellular ATP/ADP ratio and energy charge in intact growing tubers. It was estimated that at least 30% of the ATP formed during respiration is consumed as a result of the large acceleration of the cycle of sucrose breakdown and re-synthesis in the transformants. Although the absolute rate of starch synthesis in short-term labelling experiments with discs rose, starch synthesis fell relative to other fluxes including respiration, and the overall starch content of the tubers was lower than in wild-type tubers. (4) External supply of amino acids to replace sucrose as an osmoticum led to a feed-back inhibition of glycolysis, but did not restore allocation to starch. (5) However, an external supply of the non-metabolizable sucrose analogue palatinose , but not sucrose itself , stimulated flux to starch in the transformants. (6) The results indicate that the impaired performance of sucrose phosphorylase-expressing tubers is attributable to decreased levels of sucrose and increased energy consumption during sucrose futile cycling, and imply that sucrose degradation via sucrose synthase is important to maintain a relatively large sucrose pool and to minimize the ATP consumption required for normal metabolic function in the wild type. [source] Agency and Terror: Evdokimov and Mass Killing in Stalin's Great TerrorAUSTRALIAN JOURNAL OF POLITICS AND HISTORY, Issue 1 2007Stephen G. Wheatcroft This article presents an account of the history of Soviet repression, which integrates our current understanding of the scale and nature of repression with a history of the agents responsible for carrying out these operations. It notes that the major shifts in the nature of repression were accompanied by shifts in the operational leadership within the security forces, and that it was largely the same groups of individuals who were responsible for the mass killing operations during the civil war, collectivization and the Great Terror. These were the groups associated with Efim Georgievich Evdokimov, which operated in Ukraine during the Civil War, in the North Caucasus in the 1920s, and in the Secret Operational Division within OGPU in 1929-1931. Evdokimov transferred into party administration in 1934 when he became party secretary for North Caucasus Krai. But he appears to have continued advising Stalin and Yezhov on Security matters, and the latter relied upon Evdokimov's former colleagues to carry out the mass killing operations that are known as "The Great Terror" in 1937-1938. [source] Microbiological and geochemical dynamics in simulated-heap leaching of a polymetallic sulfide oreBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2008Kathryn Wakeman Abstract The evolution of microbial populations involved in simulated-heap leaching of a polymetallic black schist sulfide ore (from the recently-commissioned Talvivaara mine, Finland) was monitored in aerated packed bed column reactors over a period of 40 weeks. The influence of ore particle size (2-6.5 mm and 6.5-12 mm) on changes in composition of the bioleaching microflora and mineral leaching dynamics in columns was investigated and compared to fine-grain (<2 µm) ore that was bioprocessed in shake flask cultures. Both column reactors and shake flasks were inoculated with 24 different species and strains of mineral-oxidizing and other acidophilic micro-organisms, and maintained at 37°C. Mineral oxidation was most rapid in shake flask cultures, with about 80% of both manganese and nickel and 68% of zinc being leached within 6 weeks, though relatively little of the copper present in the ore was solubilised. The microbial consortium that emerged from the original inoculum was relatively simple in shake flasks, and was dominated by the iron-oxidizing autotroph Leptospirillum ferriphilum, with smaller numbers of Acidimicrobium ferrooxidans, Acidithiobacillus caldus and Leptospirillum ferrooxidans. Both metal recovery and (for the most part) total numbers of prokaryotes were greater in the column reactor containing the medium-grain than that containing the coarse-grain ore. The bioleaching communities in the columns displayed temporal changes in composition and differed radically from those in shake flask cultures. While iron-oxidizing chemoautotrophic bacteria were always the most numerically dominant bacteria in the medium-grain column bioreactor, there were major shifts in the most abundant species present, with the type strain of Acidithiobacillus ferrooxidans dominating in the early phase of the experiment and other bacteria (At. ferrooxidans NO37 and L. ferriphilum) dominating from week 4 to week 40. With the coarse-grain column bioreactor, similar transitions in populations of iron-oxidizing chemoautotrophs were observed, though heterotrophic acidophiles were often the most abundant bacteria found in mineral leach liquors. Four bacteria not included in the mixed culture used to inoculate the columns were detected by biomolecular techniques and three of these (all Alicyclobacillus -like Firmicutes) were isolated as pure cultures. The fourth bacterium, identified from a clone library, was related to the Gram-positive sulfate reducer Desulfotomaculum salinum. All four were considered to have been present as endospores on the dried ore, which was not sterilized in the column bioreactors. Two of the Alicyclobacillus -like isolates were found, transiently, in large numbers in mineral leachates. The data support the hypothesis that temporal and spatial heterogeneity in mineral heaps create conditions that favour different mineral-oxidizing microflora, and that it is therefore important that sufficient microbial diversity is present in heaps to optimize metal extraction. Biotechnol. Bioeng. 2008;101: 739,750. © 2008 Wiley Periodicals, Inc. [source] Why Do Some Tropical Forests Have So Many Species of Trees?BIOTROPICA, Issue 4 2004Egbert Giles Leigh Jr. ABSTRACT Understanding why there are so many kinds of tropical trees requires learning, not only how tree species coexist, but what factors drive tree speciation and what governs a tree clade's diversification rate. Many report that hybrid sterility evolves very slowly between separated tree populations. If so, tree species rarely originate by splitting of large populations. Instead, they begin with few trees. The few studies available suggest that reproductive isolation between plant populations usually results from selection driven by lowered fitness of hybrids: speciation is usually a response to a "niche opportunity." Using Hubbell's neutral theory of forest dynamics as a null hypothesis, we show that if new tree species begin as small populations, species that are now common must have spread more quickly than chance allows. Therefore, most tree species have some setting in which they can increase when rare. Trees face trade-offs in suitability for different microhabitats, different-sized clearings, different soils and climates, and resistance to different pests. These trade-offs underlie the mechanisms maintaining ,-diversity and species turnover. Disturbance and microhabitat specialization appear insufficient to maintain ,-diversity of tropical trees, although they may maintain tree diversity north of Mexico or in northern Europe. Many studies show that where trees grow readily, tree diversity is higher and temperature and rainfall are less seasonal. The few data available suggest that pest pressure is higher, maintaining higher tree diversity, where winter is absent. Tree a-diversity is also higher in regions with more tree species, which tend to be larger, free for a longer time from major shifts of climate, or in the tropics, where there are more opportunities for local coexistence. RESUMEN Comprender por qué hay tantos tipos de árboles tropicales, se requiere aprender no sólo cómo las especies de árboles coexisten, sino también, cuáles factores conducen a su especiación, y qué determina la velocidad de diversificación de un clado de árboles. Muchos reportan que la esterilidad hibrida evoluciona muy lentamente entre poblaciones separadas de árboles. De ser asi, las especies de árboles raramente se originarian por la separación de grandes poblaciones; más bien empezarian con pocos árboles. Los pocos estudios disponibles sugieren que el aislamiento reproductivo entre las poblaciones vegetales usualmente resulta de selección derivada del bajo éxito de los hibridos: la especiación general-mente responde a una "oportunidad de nicho". Usando la teoria neutral de Hubbell de dinámica de bosques como hipótesis nula, nosotros mostramos que si las nuevas especies de árboles comienzan como poblaciones pequeñas, especies que ahora son communes deberian haberse expandido más rápido que lo que el azar permite. Por lo tanto, la mayoria de las especies de árboles tendrian alguna condición donde sus poblaciones podrian crecer cunando son raras. Los árboles enfrentan compromises en su adecuación por diferentes microhábitats, claros de differentes tamanos, diferentes suelos y climas, y resistencia a differentes plagas. Esros compromises sirven de base para los mecanismos que mantienen la diversidad , y al reemplazo especial de especies. Los distrubios y la especialización de microhabitats parecen ser insuficiente para mantener la diversidad , de árboles tropicales, sin embargo elloss pueden mantener diversidad de árboles al norte de México o en Europa del norte. Muchos estudios muestran que en lugares donde los árboles cresen fácilmente, la diversidad de árboles es mayor donde la temperatura y la lluvia son menos estacionales. Los pocos estudios disponibles sugieren que la presión de las plagas es mayor, manteniendo asl la diversidad de árboles en lugares donde no hay invierno. La diversidad , de árboles también es más alta en regions con más especies de árboles, las culaes tienden a ser más largas, exentas por un largo periodo de tiempo de grandes cambios climáticos, oen los trópicos donde hay más oportunidades de coexistir localmente. [source] | |||||||||||||||||||||||||||||||