9,538 research outputs found
Fine-root seasonal pattern, production and turnover rate of European beech (Fagus sylvatica L.) stands in Italy Prealps: Possible implications of coppice conversion to high forest
The aim of this study was to investigate the possible effects of coppice conversion to high forest on the beech fine-root
systems. We compared the seasonal pattern of live and dead fine-root mass (d<2 mm), production and turnover in three
beech stands that differed in management practices. Tree density was higher in the 40-year-old coppice stand than in the
stands that were converted from coppice to high forest in 1994 and 2004, respectively. We found that a reduction in tree
density reduced the total fine-root biomass (Coppice stand, 353.8 g m-2; Conversion 1994 stand, 203.6 g m-2;
Conversion 2004 stand, 176.2 g m-2) which continued to be characterised by a bimodal pattern with two major peaks,
one in spring and one in early fall. Conversion to high forest may also affect the fine-root soil depth distribution. Both
fine-root production and turnover rate were sensitive to management practices. They were lower in the Coppice stand
(production 131.5 g m-2 year-1; turnover rate 0.41 year-1) than in the converted stands (1994 Conversion stand:
production 232 g m-2 year-1, turnover rate 1.06 year-1; 2004 Conversion stand: production 164.2 g m-2 year-1,
turnover rate 0.79 year-1)
Effect of tree density on root distribution in Fagus sylvatica stands: a semi-automatic digitising device approach to trench wall method
5Knowledge of root profiles is essential for
measuring and predicting ecosystem dynamics and function.
In the present study, the effects of management
practices on root (0.5 <= ø < 20 mm) spatial distribution
were examined in a 40-year-old coppice stand (CpS 1968)
and other two stands converted from coppice to thinned
high forest in 1994 (CvS 1994) and 2004 (CvS 2004),
respectively. The use of a semi-automatic digitising device
approach was compared with a conventional root mapping
method in order to estimate the time per person required
from fieldwork to the final digital map. In July 2009, six
trench walls per stand were established according to tree
density, i.e. as equidistant as possible from all surrounding
trees. Findings highlighted differences between the stands
with CvS 1994 showing a lower number of small roots
(2 <= ø < 5 mm), a higher mean cross-sectional area
(CSA) of coarse roots (5 <= ø < 20 mm) and different root
depth distribution as compared to CpS 1968 and CvS 2004
whose values were close to each other. The three diameter
classes selected in this study showed significant relationships
in terms of number of roots, scaling down from
coarse- to small- and fine-roots. Forest management
practices significantly affected only the number of small
roots. The number of fine roots (0.5 <= ø < 2 mm) was isometrically related to their root length density (RLD,
cm cm-3). No relationship occurred with RLD of very fine
roots (ø < 0.5 mm). In conclusion, forest management
practices in terms of conversion thinnings significantly
affected belowground biomass distribution of beech forest
in space and time. In particular, frequency of coarse roots
was related to the stand tree density, frequency of small
roots was related to the cutting age. Size of coarse roots
was related to tree density but only several years after
felling. The allometric relationship occurring between fineand
small-roots highlighted how fine root number and RLD
were only indirectly affected by forest management practices.
These findings suggest that future investigations on
the effect of forest thinning practices on fine-root traits like
number, length and biomass several years after felling
cannot ignore those on small roots.openDi Iorio, A.; Montagnoli, A.; Terzaghi, M.; Scippa, G.S.; Chiatante, D.DI IORIO, Antonino; Montagnoli, A.; Terzaghi, M.; Scippa, G. S.; Chiatante, Donat
Spectrally resolved observations of atmospheric emitted radiance in the H2O rotation band
This paper presents the project Earth Cooling by Water
Vapor Radiation, an observational programme, which aims at
developing a database of spectrally resolved far infrared
observations, in atmospheric dry conditions, in order to
validate radiative transfer models and test the quality of water
vapor continuum and line parameters. The project provides
the very first set of far-infrared spectral downwelling
radiance measurements, in dry atmospheric conditions,
which are complemented with Raman Lidar-derived
temperature and water vapor profiles
Poplar woody root proteome during the transition dormancy-active growth
Woody plants living in temperate climates finely regulate their growth and development in relation to seasonal changes; their
transition from vegetative to dormancy phase represents an adaptation to their environment. Events occurring in the shoot
during onset/release from dormancy have been largely investigated, whereas in woody roots they remain completely
unknown. In recent years, we have been interested in understanding the molecular and physiological events occurring in
poplar woody root during release from dormancy. Here, we propose the results of a comparative analysis of the proteome of
poplar woody root sampled at different time points: T0 (dormancy condition), T1 (release from dormancy), and T2 (full
vegetative condition). This study identified proteins that may be involved in the long-term survival of a dormant root or
landmarking a specific time point
Constraints on planet X/Nemesis from Solar System's inner dynamics
We put full 3D constraints on a putative planet X by using the dynamics of
the inner planets of the solar system. In particular, we compute the mimium
distance of X as a function of its heliocentric latitude and longitude for
different values of its mass.Comment: LaTex, MNRAS macros. 12 pages, 4 figures, 3 tables. To appear in
Monthly Notices of the Royal Astronomical Society (MNRAS). Some typos fixe
First study on the peptidergic innervation of the brain superior sagittal sinus in humans.
The superior sagittal sinus (SSS) of the mammalian brain is a pain-sensitive intracranial vessel thought to play a role in the pathogenesis of migraine headaches. Here, we aimed to investigate the presence and the potential co-localization of some neurotransmitters in the human SSS. Immunohistochemical and double-labeling immunofluorescence analyses were applied to paraformaldehyde-fixed, paraffin-embedded, coronal sections of the SSS. Protein extraction and Western blotting technique were performed on the same material to confirm the morphological data. Our results showed nerve fibers clustered mainly in large bundles tracking parallel to the longitudinal axis of the sinus, close in proximity to the vascular endothelium. Smaller fascicles of fibers encircled the vascular lumen in a spiral fashion, extending through the subendothelial connective tissue. Isolated nerve fibers were observed around the openings of bridging veins in the sinus or around small vessels extending into the perisinusal dura. The neurotransmitters calcitonin gene related peptide (CGRP), substance P (SP), neuronal nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP), tyrosine hydroxylase (TH), and neuropeptide Y (NPY) were found in parietal nerve structures, distributed all along the length of the SSS. Overall, CGRP- and TH-containing nerve fibers were the most abundant. Neurotransmitters co-localized in the same fibers in the following pairs: CGRP/SP, CGRP/NOS, CGRP/VIP, and TH/NPY. Western blotting analysis confirmed the presence of such neurosubstances in the SSS wall. Overall our data provide the first evidence of the presence and co-localization of critical neurotransmitters in the SSS of the human brain, thus contributing to a better understanding of the sinus functional role
An extracellular transglutaminase is required for apple pollen tube growth
An extracellular form of the calcium-dependent protein-crosslinking enzyme TGase (transglutaminase) was demonstrated to be involved in the apical growth of Malus domestica pollen tube. Apple pollen TGase and its substrates were co-localized within aggregates on the pollen tube surface, as determined by indirect immunofluorescence staining and the in situ cross-linking of fluorescently labelled substrates. TGase-specific inhibitors and an anti-TGase monoclonal antibody blocked pollen tube growth, whereas incorporation of a recombinant fluorescent mammalian TGase substrate (histidine-tagged green fluorescent protein:His6– Xpr–GFP) into the growing tube wall enhanced tube length and germination, consistent with a role of TGase as a modulator of cell wall building and strengthening. The secreted pollen TGase catalysed the cross-linking of both PAs (polyamines) into proteins (released by the pollen tube) and His6-Xpr-GFP into endogenous or exogenously added substrates. A similar distribution of TGase activitywas observed in planta on pollen tubes germinating inside the style, consistent with a possible additional role for TGase in the interaction between the pollen tube and the style during fertilization
Residual vein thrombosis for assessing duration of anticoagulation after unprovoked deep vein thrombosis of the lower limbs: the extended DACUS study.
Abstract
The safest duration of anticoagulation after idiopathic deep vein thrombosis (DVT) is unknown. We conducted a prospective study to assess the optimal duration of vitamin K antagonist (VKA) therapy considering the risk of recurrence of thrombosis according to residual vein thrombosis (RVT). Patients with a first unprovoked DVT were evaluated for the presence of RVT after 3 months of VKA administration; those without RVT suspended VKA, while those with RVT continued oral anticoagulation for up to 2 years. Recurrent thrombosis and/or bleeding events were recorded during treatment (RVT group) and 1 year after VKA withdrawal (both groups). Among 409 patients evaluated for unprovoked DVT, 33.2% (136 of 409 patients) did not have RVT and VKA was stopped. The remaining 273 (66.8%) patients with RVT received anticoagulants for an additional 21 months; during this period of treatment, recurrent venous thromboembolism and major bleeding occurred in 4.7% and 1.1% of patients, respectively. After VKA suspension, the rates of recurrent thrombotic events were 1.4% and 10.4% in the no-RVT and RVT groups, respectively (relative risk = 7.4; 95% confidence interval = 4.9-9.9). These results indicate that in patients without RVT, a short period of treatment with a VKA is sufficient; in those with persistent RVT, treatment extended to 2 years substantially reduces, but does not eliminate, the risk of recurrent thrombosis
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