63,006 research outputs found
Forest and agricultural land-use-dependent CO2 exchange in Thuringia, Germany
No full textEddy covariance was used to measure the net CO2 exchange (NEE) over ecosystems differing in land use (forest and agriculture) in Thuringia, Germany. Measurements were carried out at a managed, even-aged European beech stand (Fagus sylvatica, 70-150 years old), an unmanaged, uneven-aged mixed beech stand in a late stage of development (F. sylvatica, Fraxinus excelsior, Acer pseudoplantanus, and other hardwood trees, 0-250 years old), a managed young Norway spruce stand (Picea abies, 50 years old), and an agricultural field growing winter wheat in 2001, and potato in 2002. Large contrasts were found in NEE rates between the land uses of the ecosystems. The managed and unmanaged beech sites had very similar net CO2 uptake rates (similar to-480 to -500 g C m(-2) yr(-1)). Main differences in seasonal NEE patterns between the beech sites were because of a later leaf emergence and higher maximum leaf area index at the unmanaged beech site, probably as a result of the species mix at the site. In contrast, the spruce stand had a higher CO2 uptake in spring but substantially lower net CO2 uptake in summer than the beech stands. This resulted in a near neutral annual NEE (-4 g C m(-2) yr(-1)), mainly attributable to an ecosystem respiration rate almost twice as high as that of the beech stands, despite slightly lower temperatures, because of the higher elevation. Crops in the agricultural field had high CO2 uptake rates, but growing season length was short compared with the forest ecosystems. Therefore, the agricultural land had low-to-moderate annual net CO2 uptake (-34 to -193 g C m(-2)), but with annual harvest taken into account it will be a source of CO2 (+97 to +386 g C m(-2)). The annually changing patchwork of crops will have strong consequences on the regions' seasonal and annual carbon exchange. Thus, not only land use, but also land-use history and site-specific management decisions affect the large-scale carbon balance. [References: 39
Identification of susceptibility genes for dyslexia
No full textDevelopmental dyslexia, also known as specific reading disability, is characterized by persistent difficulties in learning to read and spell in spite of adequate intelligence, education, social environment, and normal senses. It is the most common learning disability affecting 5-10% of school-aged children. The core deficit in dyslexia is believed to involve phonological processing. Dyslexia has a complex genetic basis, and family studies as well as extensive molecular genetic studies have proven the importance of genetic factors in the development of this disorder. To date, nine chromosomal regions have been identified as susceptibility loci for dyslexia; DYX1 DYX9. DYX1C1 on chromosome 15q21 was the first candidate gene suggested based on the cloning of a translocation breakpoint co-segregating with dyslexia.The aim of this thesis project was to identify susceptibility genes for dyslexia primarily by using a positional cloning approach. Specifically, three candidate loci for dyslexia were studied; DYX1, DYX2, and DYX3. Several rounds of genetic mapping within the DYX3 region lead to the identification of overlapping dyslexia risk haplotypes in two independent sample sets. Carriers of the risk haplotype showed attenuated expression of two co-expressed genes within the region, MRPL19 and C2ORF3, indicating a possible regulatory effect of the risk variants. Linkage disequilibrium mapping within the most replicated susceptibility for dyslexia, DYX2, revealed a strong genetic effect for DCDC2 in dyslexic individuals, in particular in more severely affected cases. The effect of this gene as a susceptibility factor for dyslexia was confirmed by replication analysis in an independent sample set.Replication efforts of DYX1C1 have shown inconsistent results, and thus its role in the development of dyslexia has been considered unsettled. We refined the haplotype structure by analyzing additional variants within the DYX1C1 locus. The haplotypes showed association with dyslexia in a large sample set, with possible sex-specific effects. Refined mapping of another translocation within the DYX1 region co-segregating with dyslexia located the breakpoint to the complex promoter region of CYP19A1 (aromatase). Genetic variation within CYP19A1 associated with speech and language measures and dyslexia in three independent sample sets. Variation in the highly conserved brain promoter of CYP19A1 altered transcription factor binding. An aromatase inhibitor reduced dendritic growth in cultured rat neurons. Brain morphology studies of aromatase-deficient mice showed increased cortical neuronal density and occasional cortical heterotopias, similar to those observed in human dyslexic brains.To date, seven candidate susceptibility genes have been suggested for dyslexia. In addition to the ones studied in this thesis, KIAA0319 within DYX2 and ROBO1 within DYX5 have been indicated in dyslexia. Studies of the dyslexia candidate genes in rats and mice implicate neuronal migration and axon guidance as neurobiological mechanisms that likely mediate this disorder. Anatomical studies support this hypothesis as cortical abnormalities have been observed in dyslexic brains. Functional brain imaging studies show that these disrupted areas are involved in phonological processing and display abnormal activation in dyslexics. Taken together, our results and these studies implicate a biological basis for developmental dyslexia.List of scientific papersI. Peyrard-Janvid M, Anthoni H, Onkamo P, Lahermo P, Zucchelli M, Kaminen N, Hannula-Jouppi K, Nopola-Hemmi J, Voutilainen A, Lyytinen H, Kere J (2004). "Fine mapping of the 2p11 dyslexia locus and exclusion of TACR1 as a candidate gene." Hum Genet 114(5): 510-6. Epub 2004 Mar 6 https://pubmed.ncbi.nlm.nih.gov/15007729II. Anthoni H, Zucchelli M, Matsson H, Müller-Myhsok B, Fransson I, Schumacher J, Massinen S, Onkamo P, Warnke A, Griesemann H, Hoffmann P, Nopola-Hemmi J, Lyytinen H, Schulte-Körne G, Kere J, Nöthen MM, Peyrard-Janvid M (2007). "A locus on 2p12 containing the co-regulated MRPL19 and C2ORF3 genes is associated to dyslexia." Hum Mol Genet 16(6): 667-77. Epub 2007 Feb 19 https://pubmed.ncbi.nlm.nih.gov/17309879III. Schumacher J, Anthoni H, Dahdouh F, König IR, Hillmer AM, Kluck N, Manthey M, Plume E, Warnke A, Remschmidt H, Hülsmann J, Cichon S, Lindgren CM, Propping P, Zucchelli M, Ziegler A, Peyrard-Janvid M, Schulte-Körne G, Nöthen MM, Kere J (2006). "Strong genetic evidence of DCDC2 as a susceptibility gene for dyslexia." Am J Hum Genet 78(1): 52-62. Epub 2005 Nov 17 https://pubmed.ncbi.nlm.nih.gov/16385449IV. Dahdouh F, Anthoni H, Tapia-Páez I, Peyrard-Janvid M, Schulte-Körne G, Warnke A, Remschmidt H, Ziegler A, Kere J, Müller-Myhsok B, Nöthen MM, Schumacher J, Zucchelli M (2007). "Evidence of DYX1C1 as a sex-specific susceptibility factor for dyslexia." (Submitted)V. Anthoni H, Lewis BA, Fan X, Zucchelli M, Sucheston LEM, Tapia-Páez I, Taipale M, Stein CM, Hokkanen ME, Castrén E, et al (2007). "Aromatase (CYP19A1) regulates development of cognitive functions." (Submitted)</p
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Le mystere de sant Anthoni de Viennes, publié d'après une copie de l'an 1503, et sous les auspices de la Société d'études des Hautes-Alpes, par l'abbé Paul Guillaume Gap, au secrétariat de la Société d'études des Hautes-Alpes, 1884
No full textM. P. Le mystere de sant Anthoni de Viennes, publié d'après une copie de l'an 1503, et sous les auspices de la Société d'études des Hautes-Alpes, par l'abbé Paul Guillaume Gap, au secrétariat de la Société d'études des Hautes-Alpes, 1884. In: Romania, tome 14 n°54, 1885. pp. 294-297
Stable voters in an unstable party environment : continuity and change in Italian electoral behaviour
No full textM.24981-1999 Paolo Segatti, Paolo Bellucci and Marco Maraffi. 30 cm. A previous version of this paper was presented at a symposium on Political Parties : Changing Roles in Contemporary Democracies, held at the Center for Advanced Study in the Social Sciences of the Juan March Institute, Madrid, December 15-17, 1994. -- P.1. Includes bibliographical references (p. 56-59
Climatic versus biotic constraints on carbon and water fluxes in seasonally drought-affected ponderosa pine ecosystems
No full textWe investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (<10%), largest at the MS (>50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C.
No full textDE MAIESTATE / PRAESIDE M. JACOBO THOMASIO, MORALIS PHILOSOPH. P. P., PUBLICE DISPUTABIT JOHANNES DUNTE, R. L. AUTHOR & RESPON: AD DIEM 9. SEPTEMBR. H L. Q. C.
De Maiestate / Praeside M. Jacobo Thomasio, Moralis Philosoph. P. P., publice disputabit Johannes Dunte, R. L. Author & Respon: ad diem 9. Septembr. H L. Q. C. (1)
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Beiträge (21
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Diagnostic performance of P wave duration in the identification of left atrial enlargement in dogs
No full textObjectives: To determine sensitivity and specificity of P wave duration in the identification of left atrial enlargement (LAE) in dogs.
Methods: Electrocardiograms (ECG) from normal dogs and dogs with various cardiovascular diseases were evaluated. Inclusion criteria were the availability of an ECG showing a stable isoelectric line, easily recognizable P waves and good quality 2D echocardiographic estimate of left atrial dimensions using the left atrial to aortic root ratio (LA/Ao).
Using a metal caliper system, P wave duration was measured to the nearest 10 msec for six consecutive heart beats; data were then averaged for each dog. The accuracy of P wave duration in predicting LAE was determined using a Receiver Operating Characteristic (ROC) analysis.
Results: 156 dogs were included in the study. Average P wave durations of 20, 30, 40 and 50 msec yielded sensitivities of 100%, 85%, 68% and 40% and specificities of 0%, 16.04%,
64.15% and 93.4%, respectively, for the diagnosis of LAE by echocardiography. The estimated Area Under Curve (AUC) of the ROC curve was 0.70 (95% confidence interval: 0.60-0.80).
Clinical significance: The diagnostic performance of P wave duration for identification of LAE in dogs presents considerable limitations
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
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