bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of height imputation strategies on stand volume estimation
Authors: Garber Sean M. , Temesgen H. , Monleon Vicente J. , Hann David W. 
Published: April 2009

Subsampling and subsequent imputation of tree heights can improve the predictive performance of stand volume estimation but may also introduce biases. Using coastal Douglas-fir data from southwest Oregon, USA, the predictive performance of several height imputation strategies for estimating stand volume was evaluated. A subsample of 1–15 trees was randomly selected per stand, and missing heights were imputed using a regional Chapman–Richards function with diameter only and diameter plus stand density measures, fitted using a nonlinear least-squares model (NFEM) and a nonlinear mixed-effects model (NMEM). Missing heights were imputed using the regional height–diameter equation and by adjusting the equation with a correction factor (NFEM) or with predicted random effects (NMEM) to calibrate the height–diameter relationship to each stand. Differences in actual stand volumes, calculated with measured heights, and predicted stand volumes, calculated using measured heights for the subsampled trees and predicted heights for those with missing heights, were used to compare the alternative height imputation methods. Precision and bias were poorest for the regional models, especially NMEM, and best for the adjusted models also using NMEM. Results suggest that a similar subsample of heights (n = 4) is required for precise stand volume estimation as has been reported for height.
Ecotypic mode of regional differentiation caused by restricted gene migration: a case in black cottonwood (Populus trichocarpa) along the Pacific Northwest coast
Authors: Xie Chang-Yi , Ying Cheng C. , Yanchuk Alvin D. , Holowachuk Diane L. 
Published: April 2009

Genetic differentiation of black cottonwood ( Populus balsamifera subsp. trichocarpa (Torr. & A. Gray ex Hook) Brayshaw) across a “no-cottonwood” belt on the coast of central British Columbia (BC), Canada, was examined using data on 3 year height, severity of infection by Valsa sordida Nitschke and Melampsora occidentalis H. Jacks., and abnormality of leaf flushing. The data were collected in a common-garden test consisting of 180 provenances of 36 drainages ranging from northern BC to Oregon, USA. The results demonstrated an ecotypic mode, north–south regional differentiation. Valsa sordida and M. occidentalis infected 41% and 89%, respectively, of the trees from the northern region, while 66% showed flushing abnormality. In contrast, only 1% and 27% of their southern counterparts were infected by the same diseases, and 1% had abnormal flushing. Trees from the northern region averaged 87% shorter than those from the south. Regional differentiation accounted for the highest amount of variation observed in all traits, with 60% in 3 year height, 34% in V. sordida, 76% in M. occidentalis, and 50% in abnormal leaf flushing. Regression analysis revealed geographic patterns that essentially reflected regional differentiation along the no-cottonwood belt. The species’ distribution biography, ecological characteristics, and life history suggest that restricted gene migration was the main factor responsible for the observed geographic patterns of genetic differentiation.
Climate response of five oak species in the eastern deciduous forest of the southern Appalachian Mountains, USA
Authors: Speer James H. , Grissino-Mayer Henri D. , Orvis Kenneth H. , Greenberg Cathryn H. 
Published: April 2009

The climatic response of trees that occupy closed canopy forests in the eastern United States (US) is important to understanding the possible trajectory these forests may take in response to a warming climate. Our study examined tree rings of 664 trees from five oak species (white ( Quercus alba L.), black ( Quercus velutina Lam.), chestnut ( Quercus prinus L.), northern red ( Quercus rubra L.), scarlet ( Quercus coccinea Münchh.)) from 17 stands in eastern Tennessee, western North Carolina, and northern Georgia to determine their climatic response. We dated the samples using skeleton plots, measured the cores, and compared the site- and regional-level tree-ring chronologies of each separate species with divisional climate data. The oldest trees in each chronology dated back to 203 years for black oak, 299 years for chestnut oak, 171 years for northern red oak, 135 years for scarlet oak, and 291 years for white oak. We successfully developed climate models via multiple regression analyses with statistically significant (P < 0.05) variables representing the Palmer Drought Severity Index and average monthly temperature for most of the site-species chronologies (average R2 = 0.15). All regional climate response models included the Palmer Drought Severity Index from either June or July as the most significant variable in the climate response, suggesting that growing-season drought is the most important factor limiting oak growth in the southeastern US. An increase in temperature and reduction in moisture is likely to reduce their competitiveness in their current locations and force these species to migrate to cooler climates, thereby greatly changing ecosystem health and stability in the southern Appalachians.
Establishment of natural regeneration under severe browsing pressure from white-tailed deer after group seed-tree cutting with scarification on Anticosti Island
Authors: Beguin Julien , Prévost Marcel , Pothier David , Côté Steeve D. 
Published: April 2009

The use of large clearcuts with protection of advance regeneration is inappropriate for regeneration of balsam fir ( Abies balsamea (L.) Mill.) under severe browsing from white-tailed deer ( Odocoileus virginianus (Zimmermann)). However, little is known about the effects of tree-retention methods along with scarification on the establishment of balsam fir in a context of severe herbivory. Consequently, we hypothesized that seed-tree-group cutting in conjunction with soil scarification creates favourable conditions for balsam fir regeneration. In 1998 and 1999 we set up three circular forest groups of different sizes (40, 60, and 80 m in diameter) surrounded by three different intensities of scarification (no treatment, single pass, double pass) in two balsam fir stands on Anticosti Island, Quebec, Canada. Moreover, we used a network of fenced and unfenced regeneration plots to evaluate the impact of white-tailed deer browsing. The results showed that up to 7 years after harvest, seed-tree-group cutting did not improve the establishment of conifer species. Scarification had a negative impact on the abundance of conifer species, whereas white birch ( Betula papyrifera Marshall) density was significantly higher in areas scarified twice than in unscarified areas. Overall, the development of palatable tree species appears unlikely at deer densities >20 individuals/km2.
A comparison of thinning methods in red pine: consequences for stand-level growth and tree diameter
Authors: Bradford John B. , Palik Brian J. 
Published: April 2009

Long-term replicated experiments that contrast thinning method (dominant thinning, thinning from below) while controlling stocking level are rare. Stand growth and tree size responses to thinning method can be useful for making decisions to achieve desired objectives, whether these are timber or wildlife habitat related. We examined data from two long-term (>50 year old) silvicultural experiments in red pine to understand how alternative thinning prescriptions influence stand-level basal area, volume, and biomass growth, as well as quadratic mean tree diameter. We found that gross growth in stands treated with dominant thinning was often, although not always, greater than growth in stands treated with thinning from below. However, the differences in growth between thinning methods are smallest at stocking levels and stand ages typical for red pine management. We found that biomass growth increases with dominant thinning were generally less than basal area or volume growth increase. Furthermore, greater gross growth associated with dominant thinning versus thinning from below must be weighed against the significantly smaller average tree sizes that result from repeated dominant thinning.
Seasonal dynamics of the radial increment of Scots pine and Norway spruce in the southern and middle boreal zones in Finland
Authors: Henttonen Helena M. , Mäkinen Harri , Nöjd Pekka 
Published: April 2009

In the Finnish National Forest Inventory thousands of trees are cored every year. Based on the increment cores we assessed the progress of the radial increment in Scots pine ( Pinus sylvestris L.) and Norway spruce ( Picea abies (L.) Karst.) during the growing season. Data for 18 and 15 years were available from the southern and middle boreal zones, respectively. No major differences were found in the progress of the radial increment between either tree species or vegetation zones. In both zones, the radial increment began at approximately the same time, in late May or early June. On average, half of the annual radial increment was completed in early July, and ceased in late July or early August. However, there was large variation among years in the progress of the radial increment. On average, the radial-increment period (10%–90% of the total increment) was 41–59 days depending on tree species and region. The increment period was slightly shorter in the middle boreal zone, as increment ended 5–11 days later in the southern boreal zone. The variation of annual radial-increment indices was related to the dates of increment onset and cessation. However, increment-period length was more closely related to the differences in increment indices.
Influence of fire and harvest on soil organic carbon in jack pine sites
Authors: Norris C. E. , Quideau S. A. , Bhatti J. S. , Wasylishen R. E. , MacKenzie M. D. 
Published: April 2009

Boreal forest soils represent a considerable reservoir of carbon on a global basis. The objective of this study was to compare the response of soil organic carbon (OC) to disturbance along two jack pine ( Pinus banksiana Lamb.) chronosequences of either fire or harvest origin. Total OC stocks were determined for the A and B horizons, and results indicated a recovery to predisturbance levels by 30 years in both chronosequences. To further characterize OC composition at all sites, we used a combination of physical fractionation of soil OC pools, 13C isotopic determination, and cross-polarization magic-angle spinning 13C nuclear magnetic resonance (NMR) spectroscopy. OC within all soils was dominated by a labile pool associated with the coarse-sand fraction. The relative importance of this labile pool increased with time since disturbance along both chronosequences. However, the fire and harvested sites differed in terms of the macromolecular composition of soil OC as determined by NMR. In particular, spectra of the forest floors from the two younger fire sites showed a high aromatic OC intensity that may be attributed to the presence of char. Interestingly, our results also indicated that with increasing time since fire, this char was transferred from the forest floors to the A horizons.
SOME EXPERIMENTAL TECHNIQUES AT STORAGE RINGS
Authors:   for the COSY accelerator group and the ANKE collaboration, HARTMANN M. 
Published: April 2009

Two experimental techniques that have been developed at the COoler SYnchrotron COSY-Jülich are presented: (i) The energy of a stored polarized proton or deuteron beam can be precisely determined by sweeping an rf magnetic dipole or solenoid field over a spin resonance. This perturbation induces a beam depolarization, which is maximal at the spin resonance's frequency. That frequency, together with the beam revolution frequency, determines the beam's kinematic γ factor, which can thus be measured with high accuracy. Therefore, the beam energy can be determined about one order of magnitude more precisely than with conventional methods based on orbit length measurements. The technique has been used at COSY for an experiment aiming at a high-precision measurement the mass of the η meson. (ii) The repeated passage of a coasting ion beam through a thin internal target leads to a beam-energy loss and a shift of its revolution frequency. This shift is proportional to the beam-target overlap and thus allows one to measure the target thickness and hence the luminosity during the corresponding experiment. This effect has been studied quantitatively with a 2.65 GeV proton beam impinging on a hydrogen cluster-jet target at the ANKE spectrometer. After a careful error evaluation the luminosity, could be determined with an accuracy of better than 5%.
PRODUCTION OF HYDROGEN, NITROGEN AND ARGON PELLETS WITH THE MOSCOW-JÜLICH PELLET TARGET
Authors: BÜSCHER M. , BOUKHAROV A. , SEMENOV A. , GERASIMOV A. , CHERNETSKY V. , FEDORETS P. 
Published: April 2009

Targets of frozen droplets ("pellets") from various liquefiable gases like H 2, D 2, N 2, Ne , Ar , Kr and Xe are very promising for high luminosity experiments with a 4π detector geometry at storage-rings. High effective target densities (> 1015 atoms / cm 2), a small target size (⊘ ≈ 20–30 μ m ), a low gas load and a narrow pellet beam are the main advantages of such targets. Pioneering work on pellet targets has been made at Uppsala, Sweden.1 A next generation target has been built at the IKP of FZJ in collaboration with two institutes (ITEP and MPEI) from Moscow, Russia. It is a prototype for the future pellet target at the PANDA experiment at FAIR/HESR (supported by INTAS 06-1000012-8787, 2007/08) and makes use of a new cooling and liquefaction method, based on cryogenic liquids instead of cooling machines.2 The main advantages of this method are the vibration-free cooling and the possibility for cryogenic jet production from various gases in a wide range of temperatures. Different regimes of pellet production from H 2, N 2 and Ar have been observed and their parameters have been measured.3 For the first time, mono-disperse and satellite-free droplet production was achieved for cryogenic liquids from H 2, N 2 and Ar .
In-vitro evaluation of anti-factor IXa aptamer on thrombin generation, clotting time, and viscoelastometry
Authors: Tanaka Kenichi , Szlam Fania , Rusconi Christopher , Levy Jerrold 
Published: April 2009

SummaryThe REG1 system consists of factor IXa inhibitor, RB006, an ap-tamer-based anticoagulant and its antidote, RB007. The optimal use of RB006 can be facilitated by understanding its effect on the formation of thrombin and fibrin, and other standard tests of coagulation. Blood from consented volunteers was drawn into 3.2% citrate (9:1 v/v) and either used immediately or centrifuged to obtain platelet-poor plasma. Increasing concentrations of ap-tamer (6–24 μg/ml) alone or in combination with heparin (0.1 U/ml) or lepirudin (0.2 μg/ml) were added to blood and plasma samples. Activated clotting times (ACT+, low range-ACT), thrombelastometry (ROTEM™) or thrombelastography (TEG®) were performed in recalcified whole blood samples. Thrombin generation, prothrombin time (PT) and activated partial thromboplastin time (aPTT) were performed in plasma samples. To some samples the antidote RB007 was added to neutralise the anticoagulation activity of RB006. In all experiment the ratio of RB006 to RB007 was kept 1:2. RB006 dose-dependently prolonged aPTT and low range-ACT, but, as expected, had no effect on PT. RB006 prolonged the lag time and decreased the peak of Actin-triggered thrombin generation. Thrombin-activated TEG demonstrated that RB006 decreases the rate of clot formation. These effects were potentiated when RB006 was combined with heparin or lepirudin. In all experiments RB007 reversed the effects of RB006 back to baseline. In conclusion, RB006 inhibits thrombin generation and clot formation in a concentration-dependent manner. It is feasible to monitor RB006 and its reversal with RB007 using aPTT, low range-ACT, and thrombin-activated TEG.
Talin-dependent integrin signalling in vivo
Authors: Petrich Brian 
Published: April 2009

SummaryIntegrins are heterodimeric adhesion receptors essential for metazoan life. In addition to mediating cell-extracellular matrix and cell-cell interactions, integrins are bona fide signalling receptors in that they transmit information in both directions across the plasma membrane. The affinity of integrins for extracellular ligands is regulated through a process termed integrin activation or “inside-out signalling”. On the other hand, ligand binding to integrins can induce the recruitment and activation of a number of enzymes and adaptors such as pp125FAK and Src family kinases, to initiate “outside-in signalling”. Intensive investigation into the mechanisms of integrin signalling has revealed many of the key players; amongst these, one of the most important is talin. Our understanding of how many of these molecules interact is now understood at the atomic level thanks to detailed structural studies. Indeed structural information and model cell systems have provided unique opportunities to dissect the molecular mechanisms of many aspects of integrin signalling. Recent studies have begun testing the biological significance of these mechanisms using in-vivo models, particular genetically modified mice. The generation and characterisation of in-vivo models to study integrin signalling has provided valuable information into the functional significance of integrin signalling in fundamental physiological processes as well as within the context of human disease. Here, I will review recent insights that have been gained into integrin signalling through the use of genetically modified mice focusing on integrin αIIbβ3 (GPIIb-IIIa) and the regulation of its function in haemostasis and thrombosis.
Regulation of urokinase receptor function and pericellular proteolysis by the integrin α5β1
Authors: Bass Rosemary , Ellis Vincent 
Published: April 2009

SummaryInteractions between the uPA receptor (uPAR) and various inte-grins, including α5β1, are known to modulate integrin-dependent cell adhesion, and we have shown that the integrin-associated tetraspanin protein CD82 down-regulates uPAR-dependent plasminogen activation by affecting α5β1 cellular localisation. Here we have investigated whether overexpression of α5β1 directly affects uPAR-dependent pericellular proteolysis. CHO cells overexpressing α5β1 were found to activate plasminogen at a rate up to 18-fold faster than B2CHO cells which are α5-deficient. This effect was dependent on the activation state of α5β1, as it was maximal in the presence of Mn2+. To determine the role of uPAR-α5β1 interactions in this effect, we determined the adhesion of these cells to immobilised soluble uPAR (suPAR). Neither cell-type was found to adhere to suPAR, but both cell types were found to adhere to an anti-uPAR monoclonal antibody in a uPAR- and integrin-dependent manner. This adhesion was 10-fold greater in the absence of α5β1, possibly implicating the involvement of non-α5-integrins. Soluble forms of the various components were used to investigate the molecular basis of these effects, but no direct interactions could be demonstrated between α5β1 and either uPAR, uPA or uPA-uPAR complex. This suggests that assembly of these components on the plasma membrane is required to influence uPAR function, increasing uPAR-dependent pericellular proteolysis and decreasing uPAR-dependent cell adhesion. These interactions may be modified by other integrins, suggesting a complex interplay between uPAR and integrins on the cell surface with the potential to regulate invasive cell migration.
Coagulation factor XIII serves as protein disulfide isomerase
Authors: Bagoly Zsuzsa , Sheptovitsky Vera , Dardik Rima , Lahav Judith , Karniel Eli , Inbal Aida 
Published: April 2009

SummaryTissue transglutaminase was reported to act as protein disulfide isomerase (PDI). We studied whether plasma transglutaminase – coagulation factor XIII (FXIII) – has PDI activity as well. PDI activity was measured by determining the ability to renature reduced-denatured RNase (rdRNase). We found that FXIII can re-nature rdRNase, with efficiency comparable to commercial PDI. This PDI activity was inhibited by bacitracin. Like tissue transglu-taminase, FXIII-mediated PDI activity is independent of its transglutaminase activity and is located on the A subunit. Surface-associated PDI has been previously shown to catalyse two distinct functions: transnitrosation with subsequent release of intracellular nitric oxide and disulfide bond rearrangement during platelet integrin ligation. Our results imply that FXIII-PDI activity may have a role in platelet function.
Gender differences in stroke risk of atrial fibrillation patients on oral anticoagulant treatment
Authors: Antonucci Emilia , Grifoni Elisa , Abbate Rosanna , Gensini Gian Franco , Prisco Domenico , Poli Daniela 
Published: April 2009

SummaryThe efficacy of adjusted-dose oral anticoagulant treatment (OAT) in the prevention of stroke in atrial fibrillation (AF) is well documented. Available data show that AF patients are widely heterogeneous in terms of ischaemic stroke risk. The role of female gender as a predictor of stroke risk is inconsistent, in particular it is unclear if warfarin treatment is able to prevent stroke equally in both sexes. We performed a prospective study on 780 AF patients on OAT, followed by an Anticoagulation Clinic, to evaluate if female gender is a risk factor for stroke among patients on OAT and if the quality of anticoagulation is different between genders. No difference was found in relation to the quality of anticoagulation between genders (p=0.5). During follow-up 33 patients had major bleedings (rate 1.37x100 pt/yrs) but no difference was found between genders in bleeding risk. Forty patients had ischaemic events [rate 1.66x100 pt/yrs; males rate 1.2 x100 pt/yrs; females rate 2.43x100 pt/yrs; p=0.042; relative risk (RR) of females vs. males 2.0 (95% confidence interval [CI] 1.3–3.1); p= 0.004]. The higher rate of ischaemic events in females with respect to males was confirmed at Cox regression analysis after correction for age (p=0.009). In addition, strokes occurring in females were more disabling, and RR for severe and fatal stroke, defined according to Modified Rankin scale, of females vs. males was 3.1 (95% CI 1.3–6.5; p=0.001). In conclusion, our data show a higher risk of stroke in anticoagulated AF females with respect to males, despite a similar quality of anticoagulation.
Plasma elimination kinetics for factor VII are independent of its activation to factor VIIa and complex formation with plasma inhibitors
Authors: Elm Torben , Ezban Mirella , Krogh Thomas , Karpf Ditte , Steinø Anne , Olsen Eva , Sørensen Brit , Petersen Lars 
Published: April 2009

SummaryThe mechanism for the elimination of factor VII (FVII) from the circulation is unknown, just as it is unclear how activation of FVII to FVIIa and subsequent complex formation with antithrombin III (AT) or α2-macroglobulin (α2M) affects clearance. The possibility that the clearance mechanism involves activation and inhibitor complex formation as obligatory intermediate reactions is examined in this study. Human and murine sera were spiked with human FVIIa in the absence and presence of heparin and analysed for complex formation. Complex formation in vivo was studied after intravenous injection of 125I-VIIa in mice; and the pharmacokinetics (PK) of human and murine FVIIa was studied in normal mice. Furthermore, comparative PK studies were performed with FVII, FVIIa, active site blocked FVIIa and a preformed FVIIa-AT complex in normal and α2M-deficient mice. The data demonstrated that FVIIa-AT complexes and to a much lesser extent FVIIa-α2M-complexes accumulated in vivo after FVIIa administration. FVIIa-AT accounted for about 50% of total FVIIa antigen left in the circulation after 3 hours. All FVII derivatives studied including FVII, FVIIa and FVIIa-AT were cleared with similar rates suggesting an elimination kinetics which is unaffected by FVII activation and subsequent inactivation by plasma inhibitors.