bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vertical partitioning of CO2 production within a temperate forest soil
Authors: DAVIDSON ERIC A. , SAVAGE KATHLEEN E. , TRUMBORE SUSAN E. , BORKEN WERNER 
Published: May 2006

AbstractThe major driving factors of soil CO2 production – substrate supply, temperature, and water content – vary vertically within the soil profile, with the greatest temporal variations of these factors usually near the soil surface. Several studies have demonstrated that wetting and drying of the organic horizon contributes to temporal variation in summertime soil CO2 efflux in forests, but this contribution is difficult to quantify. The objectives of this study were to partition CO2 production vertically in a mixed hardwood stand of the Harvard Forest, Massachusetts, USA, and then to use that partitioning to evaluate how the relative contributions of CO2 production by genetic soil horizon vary seasonally and interannually. We measured surface CO2 efflux and vertical soil profiles of CO2 concentration, temperature, water content, and soil physical characteristics. These data were applied to a model of effective diffusivity to estimate CO2 flux at the top of each genetic soil horizon and the production within each horizon. A sensitivity analysis revealed sources of uncertainty when applying a diffusivity model to a rocky soil with large spatial heterogeneity, especially estimates of bulk density and volumetric water content and matching measurements of profiles and surface fluxes. We conservatively estimate that the O horizon contributed 40–48% of the total annual soil CO2 efflux. Although the temperature sensitivity of CO2 production varied across soil horizons, the partitioning of CO2 production by horizon did not improve the overall prediction of surface CO2 effluxes based on temperature functions. However, vertical partitioning revealed that water content covaried with CO2 production only in the O horizon. Large interannual variations in estimates of O horizon CO2 production indicate that this layer could be an important transient interannual source or sink of ecosystem C.
14C – a tool for separation of autotrophic and heterotrophic soil respiration
Authors: HAHN VOLKER , HÖGBERG PETER , BUCHMANN NINA 
Published: May 2006

AbstractWe assessed the potential of using 14C contents of soil respired CO2 to calculate the contributions of heterotrophic and autotrophic respiration to total soil respiration. The partitioning of these fluxes is of utmost importance to evaluate implications of environmental change on soil carbon cycling and sequestration. At three girdled forest stands in Sweden and Germany, where the tree root (autotrophic) respiration had been eliminated, we measured both flux rates and 14C contents of soil respired CO2 in girdled and control plots in the summers of 2001 or 2002. At all stands, CO2 flux rates were slightly higher in the control plots, whereas the 14C contents of respired CO2 tended to be higher in the girdled plots. This was expected and confirmed that heterotrophically respired CO2 cycles more slowly through the forest ecosystem than autotrophically respired CO2. On the basis of these data, the contributions of hetero‐ and autotrophic respiration to total soil respiration were calculated using two separate approaches (i.e. based on flux rates or 14C). Fractions of heterotrophic respiration ranged from 53% to 87%. Values calculated by both approaches did not differ significantly from each other. Finally, we compared the 14C contents of soil respired CO2 in the girdled plots with the 14C contents of heterotrophically respired CO2 calculated by three different 14C models. None of the models matched the measured data sufficiently. In addition, we suspect that inherent effects of girdling may cause the 14C content of CO2 respired in the girdled plots to be lower than ‘true’ heterotrophically respired CO2 in an undisturbed plot. Nevertheless, we argue that measurements and modeling of 14C can be developed into a valuable tool for separating heterotrophic and autotrophic soil respiration (e.g. when girdling cannot be performed).
Determining biogeographical patterns of dispersal and diversification in oscine passerine birds in Australia, Southeast Asia and Africa
Authors: Jønsson Knud A. , Fjeldså Jon 
Published: May 2006

AbstractAim  Several independent studies suggest that oscine passerine birds originated in Eastern Gondwana/Australia and from there spread to Southeast Asia and then to Africa. A recently constructed supertree including 1724 oscine taxa forms the basis for this study, in which we present a more detailed hypothesis of this out‐of‐Australia scenario.Location  Australia, Africa, Southeast Asia, western Pacific, Indian Ocean.Methods  We used the computer program DIVA to identify putative ancestral areas for each node. We also applied a molecular clock calibrated with three recently conducted studies of passerines to estimate the ages of basal nodes. Although these time estimates are rough they give some indication that, together with the putative ancestral areas, they can be compared with known events of plate tectonic movements in the Australian, Southeast Asian and western Pacific regions.Results  The DIVA analysis shows that Basal Corvida and Crown Corvida originated in Australia. Ancestral nodes for Picathartes/Chaetops and Passerida originated in Africa, and the basal nodes of Sylvioidea also originated in Africa. For Muscicapoidea and Passeroidea we were unable to establish ancestral patterns. The molecular clock showed that Crown Corvida radiated between 20 and 30 Ma whereas Basal Corvida and the Passerida clade radiated from c. 45 to 50 Ma.Main conclusions  Both approaches agree that: (1) Crown Corvida spread from Australia to Southeast Asia, with several dispersal events around the time when the terranes of Australian and Indomalayan origin came close together some 15 Ma, and (2) a single dispersal event went from Australia across the Indian Ocean to Africa c. 45–50 Ma, leading to the very large radiation of the parvorder Passerida. The latter hypothesis is novel, and contrary to the general view that oscines spread exclusively via Southeast Asia.
Odor identification accuracy declines following 24 h of sleep deprivation
Authors: KILLGORE WILLIAM D. S. , McBRIDE SHARON A. 
Published: May 2006

SummaryBrain imaging studies demonstrate that sleep deprivation reduces glucose metabolism and blood flow in the prefrontal cortex, and such reductions are associated with impairments in cognitive functioning. Although some of the greatest metabolic declines occur within the orbitofrontal cortex, little is known about the effects of sleep loss on the types of processes mediated by this region, including emotion, motivation, feeding, and olfaction. The present study tested odor identification accuracy when individuals were well rested and again following 24 h of wakefulness. Relative to rested baseline performance, sleep‐deprived individuals demonstrated a significant decline in the ability to identify specific odors on the Smell Identification Test. This decrement in olfactory functioning occurred concomitantly with slowed psychomotor speed and increased ratings of self‐reported sleepiness. Performance on a task that required complex mental set shifting did not change significantly following sleep deprivation, suggesting that the decrements in odor identification could not be attributed to task difficulty. Finally, while there was no relationship between subjective sleepiness and odor identification at rested baseline, greater subjective sleepiness was associated with better odor identification ability following 24 h of sleep loss. Possible implications of these findings are discussed.
Evaluating the awakening criterion in the definition of nightmares: how certain are people in judging whether a nightmare woke them up?
Authors: BLAGROVE MARK , HAYWOOD SUZANNE 
Published: May 2006

SummaryThere is debate about whether to include in the definition of nightmares a criterion that the imagery or emotions of the nightmare caused the person to wake up. This study investigates whether people believe that they can judge this cause of awakening. 42 participants recorded for 14 nights whether they had a dream, and decided for each dream whether it had or had not woken them. They then rated on a 5‐point scale (where 1 = very certain and 5 = very uncertain) how certain they were in their decision of whether or not the dream woke them. Participants’ mean certainty was high for decisions that the dream woke them (mean certainty = 1.60), and for very unpleasant dreams this mean certainty that the dream woke them was very high (mean certainty = 1.27). Dreams judged to have caused awakening were found to be more unpleasant than dreams judged not to have caused awakening. Although the inclusion of the awakening criterion did not increase the association of nightmare frequency with anxiety, there may be other advantages in the use of the awakening criterion.
Who is pre‐occupied with sleep? A comparison of attention bias in people with psychophysiological insomnia, delayed sleep phase syndrome and good sleepers using the induced change blindness paradigm
Authors: MARCHETTI LAUREN M. , BIELLO STEPHANY M. , BROOMFIELD NIALL M. , MACMAHON KENNETH M. A. , ESPIE COLIN A. 
Published: May 2006

SummaryCognitive models of insomnia suggest that selective attention may be involved in maintaining the disorder. However, direct assessment of selective attention is limited. Using the inducing change blindness (ICB) paradigm we aimed to determine whether there is attentional preference for sleep‐related stimuli in psychophysiological insomnia (PI) relative to delayed sleep phase syndrome (DSPS) and good sleepers (GS). In the ICB task, a visual scene, comprising both sleep‐related and neutral stimuli, ‘flickers’ back and forth with one element (sleep or neutral) of the scene changing between presentations. Therefore, a 2 × 3 totally between‐participants design was employed. The dependent variable was the number of flickers it took for the participant to identify the change. Ninety individuals (30 per group) were classified using ICSD‐R criteria, self‐report diaries and wrist actigraphy. As predicted, PI detected a sleep‐related change significantly quicker than DSPS and GS, and significantly quicker than a sleep‐neutral change. Unexpectedly, DSPS detected a sleep‐related change significantly quicker than GS. No other differences were observed between the two controls. These results support the notion that there is an attention bias to sleep stimuli in PI, suggesting that selective attention tasks such as the ICB may be a useful objective index of cognitive arousal in insomnia. The results also suggest that there may be an element of sleep preoccupation associated with DSPS. Results are discussed with reference to other experiments on attentional processing in insomnia.
Challenging sleep in aging: the effects of 200 mg of caffeine during the evening in young and middle‐aged moderate caffeine consumers
Authors: DRAPEAU CAROLINE , HAMEL‐HÉBERT Isabelle , ROBILLARD RÉBECCA , SELMAOUI BRAHIM , FILIPINI DANIEL , CARRIER JULIE 
Published: May 2006

SummaryThe aim of this study was to evaluate the effects of a 200‐mg administration of caffeine on polysomnographic sleep variables and quantitative sleep electroencephalography (EEG) in 12 young (20–30 years) and 12 middle‐aged (40–60 years) moderate caffeine consumers (one to three cups of coffee per day). All subjects were submitted to both a caffeine (200 mg) and placebo (lactose) condition in a double‐blind cross‐over design. The conditions were separated by 1 week. Compared with the placebo condition, the evening ingestion of caffeine lengthened sleep latency, reduced sleep efficiency, and decreased sleep duration and amount of stage 2 sleep in both age groups. Caffeine also reduced spectral power in delta frequencies in frontal, central and parietal brain areas, but not in prefrontal (PF) and occipital regions. Moreover, caffeine increased spectral power in beta frequencies in frontal and central brain areas in both age groups. A suppression of spectral power in the PF area in low delta frequencies (0.5–1.00 Hz) and a rise in spectral power in the parietal region in high alpha (10.00–12.00 Hz) and beta frequencies (17.00–21.00, 23.00–25.00, 27.00–29.00 Hz) occurred solely in middle‐aged subjects. No such changes were noticeable in young subjects. Generally, caffeine produced similar effects in young and middle‐aged subjects. Only a few frequency bins showed more effects of caffeine in middle‐aged subjects compared with young subjects. Furthermore, sleep EEG results do not entirely support the hypothesis that caffeine fully mimics the effects of a reduction of homeostatic sleep propensity when following a normal sleep–wake cycle.
Sleep‐dependent changes in cerebral oxygen consumption in newborn lambs
Authors: SILVANI ALESSANDRO , ASTI VALENTINA , BERTEOTTI CHIARA , FERRARI VERA , FRANZINI CARLO , LENZI PIERLUIGI , WILD JENNENE , GRANT DANIEL ALLEN , WALKER ADRIAN MARK , ZOCCOLI GIOVANNA 
Published: May 2006

SummaryDuring rapid‐eye‐movement (REM) sleep in adult subjects, the cerebral metabolic rate of oxygen consumption (CMRO2) is as high as that during wakefulness. We investigated whether CMRO2 during active sleep is already at the waking level in newborn life, to support the role of active sleep as a state of endogenous brain activation during early postnatal development. Newborn lambs, 2–5 days old (n = 6), were instrumented with electrodes for sleep‐state scoring, catheters for blood sample withdrawal and pressure monitoring, and a transit‐time ultrasonic blood‐flow probe around the superior sagittal sinus. At the age of 19 ± 3 days, blood samples were obtained simultaneously from the carotid artery and the superior sagittal sinus during uninterrupted epochs of wakefulness, quiet sleep, and active sleep. The arteriovenous difference in blood oxygen concentration was multiplied by cerebral blood flow to determine CMRO2. CMRO2 during active sleep (47 ± 5 μmol min−1) was similar to the value in wakefulness (44 ± 6 μmol min−1) and significantly higher than in quiet sleep (39 ± 5 μmol min−1, P < 0.05). These data show that active sleep provides newborn lambs with brain activity at a level similar to that in wakefulness in terms of cerebral oxygen metabolism. The high CMRO2 during active sleep supports its functional role during early postnatal development, when time spent in active sleep is at a lifetime maximum, albeit constituting a metabolic challenge for newborns, because of the impairment of systemic and cerebral vascular regulation in this sleep state.
TV exposure associated with sleep disturbances in 5‐ to 6‐year‐old children
Authors: PAAVONEN E. JUULIA , PENNONEN MARJO , ROINE MIRA , VALKONEN SATU , LAHIKAINEN ANJA RIITTA 
Published: May 2006

SummaryThe aim of this study was to investigate the effects of various forms of TV exposure on the quality of children's sleep. In this randomized population‐based survey questionnaires concerning TV viewing, sleep disturbances, and psychiatric symptoms were administered to 321 parents of children aged 5–6 years. Sleep disturbance scores were the main outcome measures. Active TV viewing and passive TV exposure were related to sleeping difficulties, especially sleep–wake transition disorders and overall sleep disturbances. Particularly, passive TV exposure and viewing adult‐targeted TV programs were strongly related to sleep disturbances. The association remained significant when socioeconomic status, family income, family conflicts, the father's work schedule, and the child's psychiatric symptoms were controlled statistically. The adjusted odds ratios were 2.91 (95% CI 1.03–8.17) and 3.01 (95% CI 1.13–8.05), respectively. TV viewing and particularly passive TV exposure and viewing adult‐targeted programs significantly increase the risk of sleeping difficulties. The results suggest that health‐care professionals should be aware of the association between TV exposure and sleep disturbances.
A house dust mite allergen homologue from poultry red mite Dermanyssus gallinae (De Geer)*
Authors: NISBET A. J. , HUNTLEY J. F. , MacKELLAR A. , SPARKS N. , MCDEVITT R. 
Published: May 2006

SUMMARY Tropomyosin is an allergenic, actin‐binding protein and a proposed vaccine candidate from several species of parasite. Tropomyosin cDNA, obtained by polymerase chain reaction (PCR) amplification from Dermanyssus gallinae RNA, encoded a predicted protein with 89% and 88% identity to tropomyosins from the ticks Boophilus microplus and Haemaphysalis longicornis, respectively, and 85% identity to the house dust mite (HDM) tropomyosin Der p 10. Mouse antibodies raised against HDM tropomyosin reacted with a band of 38 kDa on Western blots of D. gallinae extract, consistent with the molecular masses of acarine tropomyosins and the putative product of the cDNA encoding D. gallinae tropomyosin. When the same preparation of D. gallinae proteins was used in Western blots with serum from infested hens, the IgY component of the serum bound to a number of mite proteins, but not to tropomyosin, indicating that hens are not directly exposed to this allergen during a natural infestation. Immunolocalization of tropomyosin in mites indicated a ubiquitous distribution of the molecule in mite tissues. Immunolocalization and Western blotting also indicated that poultry red mites ingest host IgY.
The dehydrogenase‐mediated recycling of NADPH is a key antioxidant system against salt‐induced oxidative stress in olive plants
Authors: VALDERRAMA RAQUEL , CORPAS FRANCISCO J. , CARRERAS ALFONSO , GÓMEZ‐RODRÍGUEZ MARÍA V. , CHAKI MOUNIRA , PEDRAJAS JOSÉ R. , FERNÁNDEZ‐OCAÑA ANA , DEL RÍO LUIS A. , BARROSO JUAN B. 
Published: May 2006

ABSTRACTNADPH is an important molecule in the redox balance of the cell. In this paper, using olive tissue cultures as a model of the function of the NADPH‐generating dehydrogenases in the mechanism of oxidative stress induced by severe salinity conditions was studied. When olive (Olea europaea) plants were grown with 200 mm NaCl, a 40% reduction in leaf fresh weight was produced. The content of non‐enzymatic antioxidants such as ascorbate and glutathione was diminished between 20% to 39%, whereas the H2O2 content was increased threefold. In contrast, the analysis of the activity and protein contents of the main antioxidative enzymes showed a significant increase of catalase, superoxide dismutase and glutathione reductase. Overall, these changes strongly suggests that NaCl induces oxidative stress in olive plants. On the other hand, while the content of glucose‐6‐phosphate was increased almost eightfold in leaves of plants grown under salt stress, the content of NAD(P)H (reduced and oxided forms) did not show significant variations. Under salt stress conditions, the activity and protein contents of the main NADPH‐recycling enzymes, glucose‐6‐phosphate dehydrogenase (G6PDH), isocitrate dehydrogenase (ICDH), malic enzyme (ME) and ferrodoxin‐NADP reductase (FNR) showed an enhancement of 30–50%. In leaves of olive plants grown with 200 mm NaCl, analysis of G6PDH by immunocytochemistry and confocal laser scanning microscopy showed a general increase of this protein in epidermis, palisade and spongy mesophyll cells. These results indicate that in olive plants, salinity causes reactive oxygen species (ROS)‐mediated oxidative stress, and plants respond to this situation by inducing different antioxidative enzymes, especially the NADPH‐producing dehydrogenases in order to recycle NADPH necessary for the protection against oxidative damages. These NADP‐dehydrogenases appear to be key antioxidative enzymes in olive plants under salt stress conditions.
Jurassic septarian concretions from NW Scotland record interdependent bacterial, physical and chemical processes of marine mudrock diagenesis
Authors: HENDRY JAMES P. , PEARSON MICHAEL J. , TREWIN NIGEL H. , FALLICK ANTHONY E. 
Published: May 2006

AbstractSeptarian concretions in the Staffin Shales Formation (Kimmeridgian, Isle of Skye) allow controls on concretion rheology and septarian cracking to be investigated. Stratabound concretions consist of anhedral ferroan calcite microspar enclosing clay and minor pyrite. Intergranular volumes range from 77% to 88%, and calcite δ13C and δ18O values in most concretion bodies range from −10·0‰ to −17·3‰ and +0·3‰ to −0·6‰ respectively, consistent with rapid and pervasive cementation in marine pore fluids. Septarian rupture occurred during incipient cementation, with a sediment volume reduction of up to 43%. Crack‐lining brown fibrous calcite records pore fluid re‐oxygenation during a depositional hiatus, followed by increasing Fe content and δ13C related to bacterial methanogenesis. Brown colouration results from an included gel‐like polar organic fraction that probably represents bacterially degraded biomass. A new hypothesis for concretion growth and septarian cracking argues that quasi‐rigid ‘proto‐concretions’ formed via binding of flocculated clays by bacterial extracellular polysaccharide substances (EPS). This provided rheological and chemical conditions for tensional failure, subcritical crack growth, volume contraction, calcite nucleation, and incorporation of degraded products into crack‐lining cements. Bacterial decay of EPS and syneresis of host muds provided internal stresses to initiate rupture at shallow burial. Development of septarian (shrinkage) cracks in muds is envisaged to require pervasive in situ bacterial colonization, and to depend on rates of carbonate precipitation versus EPS degradation and syneresis. Subsequent modification of septarian concretions included envelopment by siderite and calcite microspar, hydraulic fracturing associated with Cretaceous shallow burial or Palaeogene uplift; and cementation by strongly ferroan, yellow sparry calcite that records meteoric water invasion of the host mudrocks. An abundance of fatty acids in these spars indicates aqueous transport of organic breakdown products, and δ13C data suggest a predominantly methanogenic bicarbonate source. However, the wide δ18O range for petrographically identical cement (−1·3‰ to −15·6‰) is difficult to explain.
Particle size distribution analysis of sand‐sized particles by laser diffraction: an experimental investigation of instrument sensitivity and the effects of particle shape
Authors: BLOTT SIMON J. , PYE KENNETH 
Published: May 2006

AbstractLaser diffraction is now widely used for particle size distribution analysis of sediments and soils. The technique can be very precise, and offers advantages of speed and cost over many other methods when used to analyse mixtures of sand, silt and clay. This study presents the results of an experimental investigation that examined the sensitivity of the Beckman‐Coulter LS230 instrument to mixtures of different grain populations and differences in particle shape. The instrument was found to have high sensitivity to coarse particles in a finer matrix (detection threshold 1–2%), but much lower sensitivity to finer particles in a coarser mixture (detection threshold 12–17%). Experiments using near‐spherical ballotini showed that laser analysis provides very similar values to dry sieving for the mean, median and mode, but for a range of natural sand samples values for the mean, median and mode were offset by 8–21%, with an average of ca 15%, compared with sieving. Analysis using a Beckman‐Coulter RapidVUE instrument, which provides both size and shape information, provided support for the hypothesis that the differences between laser analysis and sieving are partly attributable to the effects of particle shape. However, an additional factor is the way in which the laser software interprets the optical diffraction data. The software predicts a high degree of log‐normality in the size distribution, such that highly skewed, truncated or bimodal samples are poorly represented. Experiments using sieved fractions of ballotini indicated that, even with near‐perfectly spherical particles, the particle size distribution predicted by the laser software includes a relatively large percentage of particles outside the sieve class limits.