bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multiyear synthesis of soil respiration responses to elevated atmospheric CO2from four forest FACE experiments
Authors: King John S. , Hanson Paul J. , Bernhardt Emily , DeAngelis Paolo , Norby Richard J. , Pregitzer Kurt S. 
Published: December 2004

AbstractThe rapidly rising concentration of atmospheric CO2has the potential to alter forest and global carbon cycles by altering important processes that occur in soil. Forest soils contain the largest and longest lived carbon pools in terrestrial ecosystems and are therefore extremely important to the land–atmosphere exchange of carbon and future climate. Soil respiration is a sensitive integrator of many soil processes that control carbon storage in soil, and is therefore a good metric of changes to soil carbon cycling. Here, we summarize soil respiration data from four forest free‐air carbon dioxide enrichment (FACE) experiments in developing and established forests that have been exposed to elevated atmospheric [CO2] (168 μL L−1average enrichment) for 2–6 years. The sites have similar experimental design and use similar methodology (closed‐path infrared gas analyzers) to measure soil respiration, but differ in species composition of the respective forest communities. We found that elevated atmospheric [CO2] stimulated soil respiration at all sites, and this response persisted for up to 6 years. Young developing stands experienced greater stimulation than did more established stands, increasing 39% and 16%, respectively, averaged over all years and communities. Further, at sites that had more than one community, we found that species composition of the dominant trees was a major controller of the absolute soil CO2efflux and the degree of stimulation from CO2enrichment. Interestingly, we found that the temperature sensitivity of bulk soil respiration appeared to be unaffected by elevated atmospheric CO2. These findings suggest that stage of stand development and species composition should be explicitly accounted for when extrapolating results from elevated CO2experiments or modeling forest and global carbon cycles.
Effects of nitrogen deposition and insect herbivory on patterns of ecosystem‐level carbon and nitrogen dynamics: results from the CENTURY model
Authors: Throop Heather L. , Holland Elisabeth A. , Parton William J. , Ojima Dennis S. , Keough Cynthia A. 
Published: December 2004

AbstractAtmospheric nitrogen deposition may indirectly affect ecosystems through deposition‐induced changes in the rates of insect herbivory. Plant nitrogen (N) status can affect the consumption rates and population dynamics of herbivorous insects, but the extent to which N deposition‐induced changes in herbivory might lead to changes in ecosystem‐level carbon (C) and N dynamics is unknown. We created three insect herbivory functions based on empirical responses of insect consumption and population dynamics to changes in foliar N and implemented them into the CENTURY model. We modeled the responses of C and N storage patterns and flux rates to N deposition and insect herbivory in an herbaceous system. Results from the model indicate that N deposition caused a strong increase in plant production, decreased plant C : N ratios, increased soil organic C (SOC), and enhanced rates of N mineralization. In contrast, herbivory decreased both vegetative and SOC storage and depressed N mineralization rates. The results suggest that herbivory plays a particularly important role in affecting ecosystem processes by regulating the threshold value of N deposition at which ecosystem C storage saturates; C storage saturated at lower rates of N deposition with increasing intensity of herbivory. Differences in the results among the modeled insect herbivory functions suggests that distinct physiological and population response of insect herbivores can have a large impact on ecosystem processes. Including the effects of herbivory in ecosystem studies, particularly in systems where rates of herbivory are high and linked to plant C : N, will be important in generating accurate predictions of the effects of atmospheric N deposition on ecosystem C and N dynamics.
Sensitivity of a dynamic global vegetation model to climate and atmospheric CO2
Authors: Gerber Stefan , Joos Fortunat , Prentice I. Colin 
Published: December 2004

AbstractThe equilibrium carbon storage capacity of the terrestrial biosphere has been investigated by running the Lund–Potsdam–Jena Dynamic Global Vegetation Model to equilibrium for a range of CO2 concentrations and idealized climate states. Local climate is defined by the combination of an observation‐based climatology and perturbation patterns derived from a 4 × CO2 warming simulations, which are linearly scaled to global mean temperature deviations, ΔTglob. Global carbon storage remains close to its optimum for ΔTglob in the range of ±3°C in simulations with constant atmospheric CO2. The magnitude of the carbon loss to the atmosphere per unit change in global average surface temperature shows a pronounced nonlinear threshold behavior. About twice as much carbon is lost per degree warming for ΔTglob above 3°C than for present climate. Tropical, temperate, and boreal trees spread poleward with global warming. Vegetation dynamics govern the distribution of soil carbon storage and turnover in the climate space. For cold climate conditions, the global average decomposition rate of litter and soil decreases with warming, despite local increases in turnover rates. This result is not compatible with the assumption, commonly made in global box models, that soil turnover increases exponentially with global average surface temperature, over a wide temperature range.
Detecting changes in arctic tundra plant communities in response to warming over decadal time scales
Authors: Epstein Howard E. , Calef Monika P. , Walker Marilyn D. , Stuart Chapin F. , Starfield Anthony M. 
Published: December 2004

AbstractDetecting the response of vegetation to climate forcing as distinct from spatial and temporal variability may be difficult, if not impossible, over the typical duration of most field studies. We analyzed the spatial and interannual variability of plant functional type biomass from field studies in low arctic tussock tundra and compared these to climate change simulations of plant community composition using a dynamic tundra vegetation model (ArcVeg). Spatial heterogeneity of peak season live aboveground biomass was estimated using field samples taken from low arctic tundra at Ivotuk, Alaska (68.5°N, 155.7°W) in 1999. Coefficients of variation for live aboveground biomass at the 1 m2 scale ranged from 14.6% for deciduous shrubs, 18.5% for graminoids and 25.3% for mosses to over 57% for forbs and lichens. Spatial heterogeneity in the ArcVeg dynamic vegetation model was simulated to be greater than the field data, ranging from 37.1% for deciduous shrubs to 107.9% for forbs. Disturbances in the model, such as caribou grazing and freezing–thawing of soil, as well as demographic stochasticity, led to the greater variability in the simulated results. Temporal variances of aboveground live biomass over a 19‐year period using data from Toolik Lake, AK fell within the range of field and simulation spatial variances. However, simulations using ArcVeg suggest that temporal variability can be substantially less than site‐scale spatial variability. Field data coupled with ArcVeg simulations of climate change scenarios indicate that some changes in plant community composition may be detectable within two decades following the onset of warming, and shrubs and mosses might be the key indicators of community change. Model simulations also project increasing landscape scale spatial heterogeneity (particularly of shrubs) with increasing temperatures.
Effects of calcium concentration on the SOD activity and UVB‐induced cytotoxicity in cultured human keratinocytes
Authors: Sasaki Hiroko , Itoh Taketo , Akamatsu Hirohiko , Okamoto Hiroyuki , Horio Takeshi 
Published: December 2004

Background/Purpose: Cellular differentiation due to the extracellular calcium (Ca2+) concentration affects the level of several antioxidant enzymes in cultured human keratinocytes. Because the epidermis includes well‐ and un‐differentiated keratinocytes, we expected that keratinocytes possess different antioxidant capacity and sensitivity to damaging effects of ultraviolet‐B (UVB) depending on the differentiation. We examined the effects of Ca2+ concentration of culture medium (DMEM (Dulbecco's modified Eagle's medium)) on the superoxide dismutase (SOD) activity and UVB‐induced cytotoxicity in cultured human keratinocytes in order to investigate the relationship between cell differentiation and antioxidant defense.Methods: Human keratinocytes (HaCaT cells) were incubated in high Ca2+ (>1 mM) or low Ca2+ (<0.1 mM) concentration DMEM for 24 h at 37°C in 5% CO2. Then, we measured total SOD activity and also individual Cu,Zn‐ and Mn‐SOD activities in keratinocytes. Furthermore, after incubation in high or low Ca2+ concentration DMEM, human keratinocytes were irradiated with 10, 20 or 30 mJ/cm2 UVB. The quantity of lactate dehydrogenase (LDH) leaked in the supernatant from damaged keratinocytes, cell viability and TdT‐mediated dUTP nick end labelings (TUNEL) positive keratinocytes were measured at 24 h after UVB irradiation.Results: Total SOD activity and Cu,Zn‐SOD activity in human keratinocytes cultured in low Ca2+ were significantly lower than in keratinocytes cultured in high Ca2+ concentration DMEM. In contrast, Mn‐SOD activity was not affected. LDH leakage in the supernatant from keratinocytes cultured in low Ca2+ concentration was significantly higher than that from keratinocytes cultured in high Ca2+ concentration DMEM after UVB irradiation. The cell viability of keratinocytes cultured in low Ca2+ concentration DMEM was significantly decreased compared to that of keratinocytes cultured in high Ca2+ concentration DMEM after UVB irradiation. Furthermore, UVB‐induced apoptosis was increased in keratinocytes cultured in low Ca2+ concentration DMEM by the TUNEL method.Conclusions: These results suggest that cellular differentiation due to the change of Ca2+ concentration of culture medium affects the Cu,Zn‐SOD activity and UVB‐induced cytotoxicity in cultured human keratinocytes.
A Randomized Controlled Trial of Early Supported Discharge and Continued Rehabilitation at Home After Stroke
Authors: Thorsén Ann-Mari , Widés Holmqvist Lotta , de Pedro-Cuesta Jesús , von Koch Lena 
Published: December 2004

Background and Purpose—The optimal organization of rehabilitation services after discharge from a stroke unit has not been determined. This study sought to evaluate the effect of early supported discharge and continued rehabilitation at home (ESD), in terms of patient outcome 5 years after stroke and changes in selected data over time.Methods—Eighty-three patients from Southwest Stockholm, mildly or moderately impaired 5 to 7 days after acute stroke, were enrolled in a randomized controlled trial. The core components of the ESD service were initial treatment in a stroke unit and the involvement of an outreach team to deliver and coordinate home-based rehabilitation in partnership with the patient. At the 5-year follow-up, measures used to assess patient outcome included survival, motor capacity, dysphasia, activities of daily living (ADL), social activities, subjective dysfunction, and self-reported falls.Results—Fifty-four patients (30 in the intervention group and 24 in the control group) were evaluated 5 years after stroke, at which time a significantly larger proportion of patients in the intervention group were independent in extended ADL and active in household activities.Conclusions—This ESD service has a beneficial effect on extended ADL 5 years after stroke for mildly to moderately impaired patients.
The Zinc Finger Ikaros Transcription Factor Regulates Pituitary Growth Hormone and Prolactin Gene Expression through Distinct Effects on Chromatin Accessibility
Authors: Ezzat Shereen , Yu Shunjiang , Asa Sylvia L. 
Published: December 2004

AbstractThe Ikaros transcription factors perform critical functions in the control of lymphohematopoiesis and immune regulation. Family members contain multiple zinc fingers that mediate DNA binding but have also been implicated as part of a complex chromatin-remodeling network. We show here that Ikaros is expressed in pituitary mammosomatotrophs where it regulates the GH and prolactin (PRL) genes. Ikaros was detected by Northern and Western blotting in GH4 pituitary mammosomatotroph cells. Wild-type Ikaros (Ik1) inhibits GH mRNA and protein expression but stimulates PRL mRNA and protein levels. Ikaros does not bind directly to the proximal GH promoter but abrogates the effect of the histone deacetylation inhibitor trichostatin A on this region. Ikaros selectively deacetylates histone 3 residues on the proximal transfected or endogenous GH promoter and limits access of the Pit1 activator. In contrast, Ikaros acetylates histone 3 on the proximal PRL promoter and facilitates Pit1 binding to this region in the same cells. These data provide evidence for Ikaros-mediated histone acetylation and chromatin remodeling in the selective regulation of pituitary GH and PRL hormone gene expression.
Nouvelles données concernant le lysozyme de blanc d'œuf d'Oie: Teneur en tryptophane, stabilité et spécificité
Authors: Dianoux Anne‐Christine , Jollès Pierre 
Published: December 2004

AbstractNew data concerning the tryptophan content, the stability, and the specificity of goose egg‐white lysozyme are reported. This enzyme occupies a special place among the mammelian lysozymes already studied and the general definition of a lysozyme had to be modified. The mechanism of action is discussed.
Totalsynthese und absolute Konfiguration von natürlichem Multifloramin
Authors: Brossi A. , O'Brien J. , Teitel S. 
Published: December 2004

AbstractThe diphenol 1 was resolved into its antipodes and their absolute configuration was established. The levorotatory isomer R‐(−)‐1 was oxidized to the dienone R‐(−)‐6, which was rearranged to afford natural (−)‐multifloramine (R‐(−)‐7), thus establishing that the latter has the R‐configuration. By the same reaction sequences, the enantiomeric diphenol S‐(+)‐1 was transformed to provide (+)‐multifloramine (S‐(+)‐7) of the S‐configuration.
Indolalkaloide aus Conopharyngia durissima STAPF. 134. Mitteilung über Alkaloide [1]
Authors: Dugan J. J. , Hesse M. , Renner U. , Schmid H. 
Published: December 2004

AbstractThe alkaloids akuammiline (1) and anhydrovobasindiol (6) were isolated from the trunk bark of the Apocynacea Conopharyngia durissima STAPF. The structure of the unknown base anhydrovobasindiol was elucidated and this base was partially synthetised from the alkaloid vobasine. The well‐known akuammiline could be correlated by LiAlH4 reduction to picralinol (4).
Photochemische Reaktionen. 50. Mitteilung [1]. Zur Photochemie von gesättigten β‐Ketosulfiden II. Synthese von 6‐Hydroxy‐2‐thia‐7‐oxa‐isotwistan
Authors: Ganter C. , Moser J.‐F. 
Published: December 2004

AbstractThe results of the ultraviolet irradiation of the saturated β‐ketosulfide 2 are discussed. The photochemistry of 2 is characterized by the occurrence of two primary photoprocesses. Their efficiences depend markedly on the excited transition, (charge‐transfer)‐ or (n → π*)‐excitation, respectively. In methanol solution (charge‐transfer)‐excitation leads almost exclusively to product 7, due to (Cα – S)‐fission, and (n → π*)‐excitation to nearly equal amounts of 7 and of products 4 and 6 which result from α‐cleavage. On solvent sensibilization in benzene products 4, 6, 7 and the still unidentified product 52 are formed.Compounds 4 and 6 have been described earlier [2]. The structure elucidation of 7 is reported in this paper. Acid‐induced transformation of 7 yields the dihetero‐isotwistane 15.
Crocetindialdehyd und Crocetinhalbaldehyd als Blütenferbstoffe von Jacquinia angustifolia
Authors: Eugster C. H. , Hürlimann H. , Leuenberger H. J. 
Published: December 2004

AbstractCrocetindialdehyd und Crocetinhalbaldhyd wurden aus den Blüten von Jacquinia angustifolia isoliert.
Sur la composition de l'arôme de tomate
Authors: Viani R. , Bricout J. , Marion J. P. , Müggler‐Chavan F. , Reymond D. , Egli R. H. 
Published: December 2004

AbstractA gas‐chromatographic investigation of tomato aroma has revealed 46 components of which 32 are new. The isolation and identification of 2‐isobutyl‐thiazole, substance for the first time found in a natural aroma, are given in detail.
Photochemische Umwandlungen. 30. Mitteilung [1]. Zur Kinetik der Norbornadien‐Quadricyclan‐Photocycloaddition
Authors: Kaupp G. , Prinzbach H. 
Published: December 2004

AbstractQuantum yields for several norbornadiene → quadricyclane conversions have been determined under various experimental conditions (Tab. 1). The data are interpreted in terms of a singlet intermediate of type 15.
Die Glykoside von Vincetoxicum hirundinaria MEDIKUS. 1. Mitteilung: Isolierungen und Spaltprodukte. Glykoside und Aglykone, 316. Mitteilung
Authors: Stöckel K. , Stöcklin W. , Reichstein T. 
Published: December 2004

AbstractThe dried roots of Vincetoxicum hirundinaria MEDIKUS, collected in the lake of Garda area, yielded ca. 6% of a crude glycoside mixture, of which 5,16% consisted of relatively weakly polar material. After mild acid hydrolysis of the latter, 7 sugars could be identified through paper and thin layer chromatography, and paper electrophoresis. Of these D‐cymarose, L‐diginose, D‐digitoxose, and a small amount of lilacinobiose could be isolated in crystalline form. Of the other three sugars, D‐oleandrose was characterised as a crystalline derivative, whereas boivinose and canarose could only be identified through paper and thin layer chromatography, and paper electrophoresis.Four crystalline genins (B, D, E, G) and a glycoside (F) were isolated from the genin extract. Of these, D was very unstable and therefore thus was not further investigated. B, E, and F were shown to be 15‐oxasteroids, a type of steroids so far not found in nature. Very probably, G also represents a 15‐oxasteroid. The four substances B, E, G, and F were given the following trivial names: B = anhydrohirundigenin, E = hirundigenin, G = vincetogenin, and F = hirundoside‐A. F is an oleandroside of anhydrohirundigenin. The structures of hirundigenin and anhydrohirundigenin have already been elucidated [35].
Synthese der beiden anomeren 2‐Desoxy‐D‐ribofuranoside des 2(1H)‐Pyridons
Authors: Séquin U. , Tamm Ch. 
Published: December 2004

AbstractThe di‐p‐toluylates IV and V of the two anomeric 2‐deoxy‐D‐ribofuranosyl‐2(1 H)‐pyridones were synthesized. IV and V were characterized by their IR.‐, UV.‐ and mass spectra. The configuration was established by NMR. spectroscopy. The specific rotations show that IV and V represent exceptions to HUDSON'Srule of isorotation.
Homoberbine, eine neue Klasse heterocyclischer Verbindungen
Authors: Brossi A. , Teitel S. 
Published: December 2004

AbstractA number of rac. and optically active homoberbines have been synthesized from substituted 1‐phenethyltetrahydroisoquinolines and formaldehyde by an acid catalyzed cyclization. These homoberbines represent a new class of heterocyclic compounds which are isomeric with the homoaporphine alkaloids.
Physikalisch‐chemische, chemische und immunologische Eigenschaften der FDP‐Aldolase aus Drosophila melanogaster. 16. Mitteilung über Aldolasen [1]
Authors: Brenner‐Holzach O. , Leuthardt F. 
Published: December 2004

AbstractThe properties of pure aldolase from pupae of Drosophila melanogaster have been studied:

The molecular weight is about 159000 (s = 7.81 S, D = 4.55 · 10−7).
From the frictional ratio f/f0 = 1.236 the axial ratio for an oblong non hydrated ellipsoid of rotation can be calculated as b/a = 4.74.
The molecular activity is 2700 for FDP and approximately 200 for F‐1‐P.
Amino acid analysis shows significant differences between Drosophila aldolase and rabbit muscle and liver aldolases, especially in the contents of histidine, glycine, alanine and cysteine.
Hybridization with rabbit brain aldolase gives three new hybrids.
Anti‐Drosophila aldolase serum (guinea pig) does not precipitate rabbit muscle aldolase (type A) or rabbit brain aldolase (type C) in the OUCHTERLONY test.
Röntgen‐Kontrastmittel. 16. Mitteilung. Derivate von jodierten Benzoylamino‐phenyl‐ und Benzoylamino‐phenoxy‐alkansäuren
Authors: Felder E. , Pitrè D. , Fumagalli L. , Suter H. , Zutter H. 
Published: December 2004

AbstractA number of new [(3‐amino‐2,4,6‐triiodo‐benzoylamino)‐phenyl‐ and ‐phenoxy]‐alkanoic acids have been synthesized for evaluation as X‐ray contrast agents. The toxicity, the bilitropism, and the urotropism of these compounds were determined.
Concerning the ‘Non‐Specific’ Far Infrared Absorption of Polar Liquids
Authors: Bulkin Bernard J. 
Published: December 2004

AbstractThe far infrared spectra of dimethyl sulfoxide and several aliphatic nitriles have been studied with a view towards elucidating the mechanism responsible for the intense absorption bands which have been observed in this region. Spectra of pure liquids, solid DMSO, DMSO‐d6, CD3CN, and dilute solutions in non‐polar solvents are presented. The results are discussed in terms of the possible mechanisms proposed for these absorptions.
Kernresonanzspektren des Cyclohexa‐2,5‐dien‐1‐on‐Systems (para‐Dienone)
Authors: Regel W. , von Philipsborn W. 
Published: December 2004

AbstractProton and fluorine NMR. spectra of several para‐dienones (4‐allyl‐4‐methyl‐cyclohexa‐2,5‐diene‐1‐one and its 2‐ and 3‐fluoro derivatives, a spirocyclic bis‐dienone and two dienone alkaloids) have been analysed using multiple resonance, solvent effects, and computer techniques. The relative signs of all the H, H‐ and H, F‐coupling constants of the para‐dienone system have been determined. The nature and significance of long range coupling in cyclic and openchain cross‐conjugated dienones is discussed in comparison with related systems of aromatic character.
Die Glykoside Vincetoxicum hirundinaria MEDIKUS. 3. Mitteilung: Struktur von Hirundigenin und Anhydrohirundigenin. Glykoside und Aglykone, 318. Mitteilung
Authors: Stöckel K. , Stöcklin W. , Reichstein T. 
Published: December 2004

AbstractHirundigenin can easily be converted into anhydrohirundigenin by thermal dehydration. Both substances are stable to alkali but unstable under acid conditions. Dehydrogenation of anhydrohirundigenin, using selenium at 310°, gave a mixture of 2‐methylphenanthrene (29), 1, 2‐dimethyl‐phenanthro [1,2‐b] furan (30) and 1‐ethyl‐2‐methyl‐phenanthro [1,2‐b] furan (32), all of which could be isolated in crystalline form. The last two substances are new and their structures were confirmed by synthesis. Through these results, as well as by further reactions and spectra, it could be shown that hirundigenin and anhydrohirundigenin are 16‐methyl‐15‐oxapregnane derivatives, further, that they have two epoxide rings and that they probably have the structures 7 and 11. These structures were proved by O. Kennard et. al. through X‐ray studies of p‐bromobenzoyl‐anhydrohirundigenin (13). As far as we know, 15‐oxasteroids had not yet been found in nature.
Katalytische Cyclisierung von Acetylen und substituiertem Acetylen zu aromatischen Kohlenwasserstoffen
Authors: Dändliker G. 
Published: December 2004

AbstractThe pentahalogenides of niobium and tantalum and some tungsten chlorides catalize the cyclotrimerization of acetylenic hydrocarbons to form aromatic compounds. Acetylene is converted into benzene at atmospheric pressure and temperatures between — 20 and 130°C. Under similar conditions methylacetylene and but‐1‐yne respectively yield a mixture of the corresponding 1,2,4‐ and 1,3,5‐substituted benzenes while with but‐2‐yne hexamethyl benzene is obtained. Cocyclization between acetylene and substituted acetylenes or diacetylene is possible; in this case mono‐ and disubstituted benzenes or biphenyl, terphenyl, and polyphenyls are formed.