647 research outputs found
How citation boosts promote scientific paradigm shifts and Nobel Prizes
Nobel Prizes are commonly seen to be among the most prestigious achievements
of our times. Based on mining several million citations, we quantitatively
analyze the processes driving paradigm shifts in science. We find that
groundbreaking discoveries of Nobel Prize Laureates and other famous scientists
are not only acknowledged by many citations of their landmark papers.
Surprisingly, they also boost the citation rates of their previous
publications. Given that innovations must outcompete the rich-gets-richer
effect for scientific citations, it turns out that they can make their way only
through citation cascades. A quantitative analysis reveals how and why they
happen. Science appears to behave like a self-organized critical system, in
which citation cascades of all sizes occur, from continuous scientific progress
all the way up to scientific revolutions, which change the way we see our
world. Measuring the "boosting effect" of landmark papers, our analysis reveals
how new ideas and new players can make their way and finally triumph in a world
dominated by established paradigms. The underlying "boost factor" is also
useful to discover scientific breakthroughs and talents much earlier than
through classical citation analysis, which by now has become a widespread
method to measure scientific excellence, influencing scientific careers and the
distribution of research funds. Our findings reveal patterns of collective
social behavior, which are also interesting from an attention economics
perspective. Understanding the origin of scientific authority may therefore
ultimately help to explain, how social influence comes about and why the value
of goods depends so strongly on the attention they attract.Comment: 6 pages, 6 figure
Development of B Cells and Erythrocytes Is Specifically Impaired by the Drug Celastrol in Mice
Background: Celastrol, an active compound extracted from the root of the Chinese medicine ââThunder of God Vineââ (Tripterygium wilfordii), exhibits anticancer, antioxidant and anti-inflammatory activities, and interest in the therapeutic potential of celastrol is increasing. However, described side effects following treatment are significant and require investigation prior to initiating clinical trials. Here, we investigated the effects of celastrol on the adult murine hematopoietic system. Methodology/Principal Findings: Animals were treated daily with celastrol over a four-day period and peripheral blood, bone marrow, spleen, and peritoneal cavity were harvested for cell phenotyping. Treated mice showed specific impairment of the development of B cells and erythrocytes in all tested organs. In bone marrow, these alterations were accompanied by decreases in populations of common lymphoid progenitors (CLP), common myeloid progenitors (CMP) and megakaryocyte-erythrocyte progenitors (MEP). Conclusions/Significance: These results indicate that celastrol acts through regulators of adult hematopoiesis and could be used as a modulator of the hematopoietic system. These observations provide valuable information for further assessmen
Impact of associated injuries in the Floating knee: A retrospective study
<p>Abstract</p> <p>Background</p> <p>Floating knee injuries are usually associated with other significant injuries. Do these injuries have implications on the management of the floating knee and the final outcome of patients? Our study aims to assess the implications of associated injuries in the management and final outcome of floating knee.</p> <p>Methods</p> <p>29 patients with floating knees were assessed in our institution. A retrospective analysis of medical records and radiographs were done and all associated injuries were identified. The impact of associated injuries on delay in initial surgical management, delay in rehabilitation & final outcome of the floating knee were assessed.</p> <p>Results</p> <p>38 associated injuries were noted. 7 were associated with ipsilateral knee injuries. Lower limb injuries were most commonly associated with the floating knee. Patients with some associated injuries had a delay in surgical management and others a delay in post-operative rehabilitation. Knee ligament and vascular injuries were associated with poor outcome.</p> <p>Conclusion</p> <p>The associated injuries were quite frequent with the floating knee. Some of the associated injuries caused a delay in surgical management and post-operative rehabilitation. In assessment of the final outcome, patients with associated knee and vascular injuries had a poor prognosis. Majority of the patients with associated injuries had a good or excellent outcome.</p
Knowledge Management and Organisational Culture
This international Handbook provides a comprehensive overview of key topics, debates and issues within the now well-established field of Knowledge Management (KM)
Jellyfish Support High Energy Intake of Leatherback Sea Turtles (Dermochelys coriacea): Video Evidence from Animal-Borne Cameras
The endangered leatherback turtle is a large, highly migratory marine predator that inexplicably relies upon a diet of low-energy gelatinous zooplankton. The location of these prey may be predictable at large oceanographic scales, given that leatherback turtles perform long distance migrations (1000s of km) from nesting beaches to high latitude foraging grounds. However, little is known about the profitability of this migration and foraging strategy. We used GPS location data and video from animal-borne cameras to examine how prey characteristics (i.e., prey size, prey type, prey encounter rate) correlate with the daytime foraging behavior of leatherbacks (nâ=â19) in shelf waters off Cape Breton Island, NS, Canada, during August and September. Video was recorded continuously, averaged 1:53 h per turtle (range 0:08â3:38 h), and documented a total of 601 prey captures. Lion's mane jellyfish (Cyanea capillata) was the dominant prey (83â100%), but moon jellyfish (Aurelia aurita) were also consumed. Turtles approached and attacked most jellyfish within the camera's field of view and appeared to consume prey completely. There was no significant relationship between encounter rate and dive duration (pâ=â0.74, linear mixed-effects models). Handling time increased with prey size regardless of prey species (pâ=â0.0001). Estimates of energy intake averaged 66,018 kJâądâ1 but were as high as 167,797 kJâądâ1 corresponding to turtles consuming an average of 330 kg wet massâądâ1 (up to 840 kgâądâ1) or approximately 261 (up to 664) jellyfishâąd-1. Assuming our turtles averaged 455 kg body mass, they consumed an average of 73% of their body massâądâ1 equating to an average energy intake of 3â7 times their daily metabolic requirements, depending on estimates used. This study provides evidence that feeding tactics used by leatherbacks in Atlantic Canadian waters are highly profitable and our results are consistent with estimates of mass gain prior to southward migration
Search for supersymmetric particles in scenarios with a gravitino LSP and stau NLSP
Sleptons, neutralinos and charginos were searched for in the context of
scenarios where the lightest supersymmetric particle is the gravitino. It was
assumed that the stau is the next-to-lightest supersymmetric particle. Data
collected with the DELPHI detector at a centre-of-mass energy near 189 GeV were
analysed combining the methods developed in previous searches at lower
energies. No evidence for the production of these supersymmetric particles was
found. Hence, limits were derived at 95% confidence level.Comment: 31 pages, 14 figure
Offspring Hormones Reflect the Maternal Prenatal Social Environment: Potential for Foetal Programming?
Females of many species adaptively program their offspring to predictable environmental conditions, a process that is often mediated by hormones. Laboratory studies have shown, for instance, that social density affects levels of maternal cortisol and testosterone, leading to fitness-relevant changes in offspring physiology and behaviour. However, the effects of social density remain poorly understood in natural populations due to the difficulty of disentangling confounding influences such as climatic variation and food availability. Colonially breeding marine mammals offer a unique opportunity to study maternal effects in response to variable colony densities under similar ecological conditions. We therefore quantified maternal and offspring hormone levels in 84 Antarctic fur seals (Arctocephalus gazella) from two closely neighbouring colonies of contrasting density. Hair samples were used as they integrate hormone levels over several weeks or months and therefore represent in utero conditions during foetal development. We found significantly higher levels of cortisol and testosterone (both P < 0.001) in mothers from the high density colony, reflecting a more stressful and competitive environment. In addition, offspring testosterone showed a significant positive correlation with maternal cortisol (P < 0.05). Although further work is needed to elucidate the potential consequences for offspring fitness, these findings raise the intriguing possibility that adaptive foetal programming might occur in fur seals in response to the maternal social environment. They also lend support to the idea that hormonally mediated maternal effects may depend more strongly on the maternal regulation of androgen rather than cortisol levels
Response of the photosynthetic apparatus to a flowering-inductive period by water stress in Citrus
The photosynthetic responses to a flowering-inductive water-stress period and recovery were studied and compared in two Citrus species. Under greenhouse conditions, Fino lemon and Owari satsuma trees were subjected to moderate (-2 MPa at predawn) and severe (-3 MPa) water stress levels and were re-watered after 60 days. Vegetative growth was inhibited during the stress assays, and strong defoliation levels were reported, especially in Fino lemon. In both species, bud sprouting was induced after re-watering. Flowers and vegetative shoots developed in Owari satsuma after a drought period, and the development was independent of the stress level. In Fino lemon, vegetative shoots and flowers were primarily formed after moderate and severe stress, respectively. The photosynthetic rate and stomatal conductance were reduced by water stress, and a marked increase in water-use efficiency at the moderate water deficit level was observed. Nevertheless, the photosynthetic apparatus was not damaged, since the maximum quantum yield, photosynthetic pigment concentrations and Rubisco level and activity did not change. Furthermore, the measured malonyldialdehyde (MDA) and peroxidase activity indicated that oxidative stress was not specifically triggered by water stress in our study. Therefore, the gas exchange, fluorescence and biochemical parameters suggested that diffusional limitations to photosynthesis predominated in both of the studied Citrus species, and explained the rapid recovery of the photosynthetic parameters after rehydration. The net CO 2 fixation rate and stomatal conductance were recovered within 24 h in Fino lemon, whereas 3 days were required in Owari satsuma. This suggests the presence of some metabolic limitations in the latter species. Furthermore, the sensibility of the defoliation rates, the accumulation of proline and the stomatal behaviour in response to water stress indicated a higher drought tolerance of Fino lemon, according to its better acclimation to hot climates. © 2011 Springer-Verlag.The authors thank Dr. J. Moreno and co-workers from the Departamento de Bioquimica of the Universidad de Valencia for his help and support in the Rubisco assays, and Dr. F. Fornes, Dr. A. Calatayud and Dr. E. Primo-Millo for the critical review of the manuscript. This work was funded by the Universitat Politecnica de Valencia, Spain (Ayudas para primeros proyectos de investigacion PAID06-06).Ăvila ResĂ©ndiz, C.; Guardiola Barcena, JL.; GonzĂĄlez Nebauer, S. (2012). Response of the photosynthetic apparatus to a flowering-inductive period by water stress in Citrus. Trees - Structure and Function. 26(3):833-840. https://doi.org/10.1007/s00468-011-0657-4S833840263Addicott FT (1982) Abscission. University of California Press, BerkeleyBajji M, Kinet JM, Lutts S (1998) Salt stress effects on roots and leaves of Atriplex halimus L. and their corresponding callus. Plant Sci 137:131â142Barbera G, Fatta-del-Bosco G, Lo-Cascio B (1985) Effect of water stress on lemon summer bloom: the Forzatura technique in the Sicilian citrus industry. Acta Hortic 171:391â397Bates LS, Waldren RP, Teare ID (1973) Rapid determination of free proline for water stress studies. Plant Soil 39:205â207Bota J, Medrano H, Flexas J (2004) Is photosynthesis limited by decreased Rubisco activity and RuBP content under progressive water stress? New Phytol 162:671â681Bradford MM (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72:248â254Cassin J, Bourdeaut A, Fougue V, Furon V, Gaillard JP, LeBourdelles J, Montagut G, Moreuil C (1969) The influence of climate upon blooming of Citrus in tropical areas. Proc Int Soc Citrus 1:315â323Castel JR, Buj A (1990) Response of Salustiana oranges to high frequency deficit irrigation. Irrig Sci 11:121â127Chaikiatitiyos S, Menzel CM, Rasmussen TS (1994) Floral induction in tropical fruit trees: effects of temperature and water supply. J Hortic Sci 69:397â415Chaves MM, Flexas J, Pinheiro C (2009) Photosynthesis under drought and salt stress: regulation mechanisms from whole plant to cell. Ann Bot 103:551â560Costa JM, Ortuño MF, Chaves M (2007) Deficit irrigation as a strategy to save water: physiology and potential application to horticulture. J Integr Plant Biol 49:1421â1434Davenport TL (1990) Citrus flowering. Hortic Rev 12:249â408Davies FS, Albrigo LG (1994) Citrus. CAB International, Wallingford, pp 126â134Domingo R, Ruiz-SĂĄnchez MC, SĂĄnchez-Blanco MJ, Torrecillas A (1996) Water relations, growth and yield of Fino lemon trees under regulated deficit irrigation. Irrig Sci 16:115â123Erismann ND, Machado EC, Tucci MLS (2008) Photosynthetic limitation by CO2 diffusion in drought stressed orange leaves on three rootstocks. Photosynth Res 96:163â172Flexas J, Bota J, GalmĂ©s J, Medrano H, Ribas-CarbĂł M (2006) Keeping a positive carbon balance under adverse conditions: responses of photosynthesis and respiration to water stress. Physiol Plant 127:343â352GallĂ© A, Florez-Sarasa I, Tomas M, Pou A, Medrano H, Ribas-CarbĂł M, Flexas J (2009) The role of mesophyll conductance during water stress and recovery in tobacco (Nicotiana sylvestris): acclimation or limitation? J Exp Bot 60:2379â2390GalmĂ©s J, Medrano H, Flexas J (2007) Photosynthetic limitations in response to water stress and recovery in Mediterrenean plants with different growth forms. New Phytol 175:81â93GarcĂa-Luis A, Kanduser M, Santamarina P, Guardiola JL (1992) Low temperature influence on flowering in Citrus. The separation of inductive and bud dormancy releasing effects. Physiol Plant 86:648â652GarcĂa-SĂĄnchez F, Syvertsen JP, Gimeno V, BotĂa P, PĂ©rez-PĂ©rez JG (2007) Responses to flooding and drought stress by two citrus rootstock seedlings with different water-use efficiency. Physiol Plant 130:532â542Genty B, Briantais JM, Baker NR (1989) The relationship between quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence. Biochim Biophys Acta 990:87â92GĂłmez-Cadenas A, Tadeo FR, Talon M, Primo-Millo E (1996) Leaf abscission induced by ethylene in water-stressed intact seedlings of Cleopatra mandarin requires previous abscisic acid accumulation in roots. Plant Physiol 112:401â408Gordo O, Sanz JJ (2010) Impact of climate change on plant phenology in Mediterranean ecosystems. Glob Chang Biol 16:1082â1106Heath RL, Packer L (1968) Photoperoxidation in isolated chloroplasts. I. Kinetics and stoichiometry of fatty acid peroxidation. Arch Biochem Biophys 125:189â190Hoagland DR, Arnon DI (1950) The water culture method for growing plants without soil. California Agricultural Experiment Station Circular no. 347, p 32IPCC (2001) Climate change 2001. In: Houghton JT (ed) The scientific basis. Cambridge University Press, CambridgeLawlor DW (1995) The effects of water deficit on photosynthesis. In: Smirnoff N (ed) Environment and plant metabolism. Bios Scientific Publishers, Oxford, pp 129â160Lichtenthaler HK, Buschmann C (2001) Current protocols in food analytical chemistry, F4.2.1 and F4.3.1. John Wiley and Sons, Inc, NJLorimer GH, Badger MR, Andrews TJ (1977) D-Ribulose-1, 5-bisphosphate carboxilase-oxigenase. Improved methods for activation and assay of catalytic activities. Anal Biochem 78:66â75Miyashita K, Tanakamaru S, Maitani T, Kimura K (2005) Recovery responses of photosynthesis, transpiration, and stomatal conductance in kidney bean following drought stress. Environ Exp Bot 53:205â214Nir I, Leshem B, Goren R (1972) Effects of water stress, gibberellic acid and 2-chloroethylammoniumchloride (CCC) ob flower differentiation in Eureka lemon trees. J Am Soc Hortic Sci 97:774â778Peñarrubia L, Moreno J (1988) Ribulose 1, 5-bisphosphate carboxylase oxygenase from citrus leaves. Phytochemistry 27:1999â2004PĂ©rez-PĂ©rez JG, Syvertsen JP, BotĂa P, GarcĂa-SĂĄnchez F (2007) Leaf water relations and net gas exchange responses of salinized carrizo citrange seedlings during drought stress and recovery. Ann Bot 100:335â345PĂ©rez-PĂ©rez JG, Robles JM, Tovar JC, BotĂa P (2009) Response to drought and salt stress of lemon âFino 49â under field conditions: water relations, osmotic adjustment and gas Exchange. Sci Hortic 122:83â90Reynolds M, Tuberosa R (2008) Translational research impacting on crop productivity in drought-prone environments. Curr Opin Plant Biol 11:171â179Ruiz-SĂĄnchez MC, Domingo R, SavĂ© R, Biel C, Torrecillas A (1997) Effects of water stress and rewatering on leaf water relations of lemon plants. Biol Plant 39:623â631Sarris D, Christodoulakis D, Körner C (2007) Recent decline in precipitation and tree growth in the eastern Mediterranean. Glob Chang Biol 13:1187â1200Sharkey TD (1990) Water-stress effects on photosynthesis. Photosynthetica 24:651Southwick SM, Davenport TL (1986) Characterization of water stress and low temperature effects on flower induction in Citrus. Plant Physiol 81:26â29Spiegel-Roy P, Goldschmidt EE (1996) Biology of Citrus. Cambridge University Press, Cambridge, pp 131â136Syvertsen JP, Lloyd J (1994) Citrus. In: Schaffer BA, Andersen PC (eds) Handbook of environmental physiology of fruit crops. Vol II Subtropical and tropical crops. CRC Press, Boca Raton, pp 65â99Syvertsen JP (1996) Water stress and carbon budgets. Proc Int Soc Citrus 1:46â50Valladares F, Arrieta S, Aranda I, Lorenzo D, SĂĄnchez-GĂłmez D, Tena D, Suarez F, Pardos JA (2005) Shade tolerance, photoinhibition sensitivity and phenotypic plasticity of Illex aquifolium in continental Mediterranean sites. Tree Physiol 25:1041â1052Vu JCV, Yelenosky G (1988) Solar irradiance and drought stress effects on the activity and concentration of ribulose bisphosphate carboxylase in âValenciaâ orange leaves. Isr J Bot 37:245â25
Biochemical indices and life traits of loggerhead turtles (Caretta caretta) from Cape Verde Islands
The loggerhead turtle (Caretta caretta) is an endangered marine reptile for whom assessing population health requires
knowledge of demographic parameters such as individual growth rate. In Cape Verde, as within several populations, adult
female loggerhead sea turtles show a size-related behavioral and trophic dichotomy. While smaller females are associated
with oceanic habitats, larger females tend to feed in neritic habitats, which is reflected in their physiological condition and in
their offspring. The ratio of RNA/DNA provides a measure of cellular protein synthesis capacity, which varies depending on
changes in environmental conditions such as temperature and food availability. The purpose of this study was to evaluate
the combined use of morphometric data and biochemical indices as predictors of the physiological condition of the females
of distinct sizes and hatchlings during their nesting season and how temperature may influence the physiological condition
on the offspring. Here we employed biochemical indices based on nucleic acid derived indices (standardized RNA/DNA
ratio-sRD, RNA concentration and DNA concentration) in skin tissue as a potential predictor of recent growth rate in nesting
females and hatchling loggerhead turtles. Our major findings were that the physiological condition of all nesting females
(sRD) decreased during the nesting season, but that females associated with neritic habitats had a higher physiological
condition than females associated with oceanic habitats. In addition, the amount of time required for a hatchling to right
itself was negatively correlated with its physiological condition (sRD) and shaded nests produced hatchlings with lower sRD.
Overall, our results showed that nucleic acid concentrations and ratios of RNA to DNA are an important tool as potential
biomarkers of recent growth in marine turtles. Hence, as biochemical indices of instantaneous growth are likely
temperature-, size- and age-dependent, the utility and validation of these indices on marine turtles stocks deserves further
study.The authors thank the Cape Verde Ministry of Environment (General Direction for the Environment), INDP (National Fisheries Institution), the Canary
Islands Government (D.G. Africa and D.G. Research and Universities), ICCM (Canarian Institution for Marine Sciences), the Andalusian Government (Andalusian
Environmental Office) and AEGINA PROJECT (INTERREG IIIB) for funding and hosting them during this study. The authors also thank the European Regional
Development Fund (ERDF) through the COMPETE - Operational Competitiveness Programme, and national funds through FCT - PEst-C/MAR/LA0015/2011 for
supporting the biochemical analysis
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