7,009 research outputs found
Carbon stock and dynamics in natural regeneration in managed forest in the central Amazon.
Estoque e dinâmica do carbono na regeneração natural em floresta manejada na Amazônia Central. Cerca de 2% da biomassa viva acima do solo encontra-se na regeneração natural das espécies arbóreas. Apesar de ser um valor relativamente baixo, o diagnóstico do estrato inferior da floresta é importante no contexto atual das mudanças climáticas. O objetivo desse estudo foi avaliar os efeitos do manejo florestal no estoque e na dinâmica de carbono da regeneração natural 20 anos após a exploração em floresta na Amazônia Central. Around 2% of the living biomass above ground is found in the natural regeneration of tree species. Despite being a relatively low value, diagnosing the lower stratum of the forest is important in the current context of climate change. The aim of this study was to evaluate the effects of forest management on the carbon stock and dynamics of natural regeneration 20 years after logging in a forest in the Central Amazon
Post-traumatic malunion of the proximal phalanx of the finger. Medium-term results in 24 cases treated by "in situ" osteotomy
We report the clinical and radiographic medium-term results obtained for 20 patients (24 fingers) treated surgically for post-traumatic malunion of the proximal phalanx of the finger. In all cases we performed a corrective osteoclasia or osteotomy at the site of malunion, followed by miniplate and screw fixation or by screw fixation only. The corrective osteoclasia was performed when malalignment was addressed within six weeks after injury. Two patients who had two fractures underwent additional surgery (tenolysis and/or capsulolysis) to improve function and ROM. At the final follow-up, at a mean of 24 months after corrective surgery, good or excellent clinical and radiographic results were obtained in all the patients. The pseudoclaw deformity disappeared in all cases in which a volar angulation deformity was present. An average improvement of about 30% in the range of motion of the MP and PIP joints was observed; only 4 patients complained of mild pain at the maximum degrees of articular excursion of the MP and PIP joints. All the patients presented an improvement in grip strength. The mean DASH score in our series was 5 points. In two of the four cases treated by an intra-articular corrective osteotomy, mild radiographic signs of osteoarthritis at the MP joint were present. The data for this study confirm that "in situ" osteotomy stabilized by miniplates and/or screws is an effective procedure to correct post-traumatic malunions of the proximal phalanges of the fingers
Multiple congenital bilateral trigger digits in a 2-year-old child: case report
Trigger finger is a rare condition in children. In this paper, we report on a 2-year-old boy with multiple congenital bilateral trigger digits. The patient had no history of perinatal trauma, viral or bacterial infections, or metabolic disorders. The patient was treated with physiotherapy for one year. At the one-year follow-up, the boy presented with six trigger fingers (3 on the right hand, 3 on the left hand). Neither thumb was involved. The six trigger fingers were treated surgically: first, the right-hand trigger fingers and, six months later, those of the left hand. After each operation, a 4-week brace in extension was applied to the operated hand. The symptoms were completely resolved after surgical treatment. Many authors have recommended surgical release for the treatment of trigger finger in children; empirical treatment with physiotherapy may be an option when symptoms present or appear at an older age
Standard monomial theory for wonderful varieties
A general setting for a standard monomial theory on a multiset is introduced
and applied to the Cox ring of a wonderful variety. This gives a degeneration
result of the Cox ring to a multicone over a partial flag variety. Further, we
deduce that the Cox ring has rational singularities.Comment: v3: 20 pages, final version to appear on Algebras and Representation
Theory. The final publication is available at Springer via
http://dx.doi.org/10.1007/s10468-015-9586-z. v2: 20 pages, examples added in
Section 3 and in Section
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Imparting gas selective and pressure dependent porosity into a non-porous solid: Via coordination flexibility
Using a simple hard-soft acid-base concept we have deliberately designed gas-specific and pressure dependent porosity into a non-porous solid via coordination flexibility. This creates distinct gate-openings wherein the CO2 molecule opens-up the framework pores by rotating the ligand about the weaker hard-soft bonds (hard-soft gate control). For this, we have studied the CO2 gating behaviour of M(4-PyC)2 (M = Mg, Mn and Cu), which represent metals of varying hardness. A combination of quantum chemical calculations, molecular dynamics and Grand canonical Monte Carlo simulations were performed to examine the gate opening of the isonicotinate ligands in Mg(4-PyC)2. The simulations show that interaction of the CO2 molecules with the isonicotinate ligands at different CO2 loadings can result in pressure-dependent gate opening. Furthermore, the simulated CO2 uptake values calculated using the partially gate-opened structures at different loadings showed good agreement with the experimental uptake values. This provides an effective strategy for designing highly-stable dynamic porous solids employing rigid frameworks
Universal restrictions to the conversion of heat into work derived from the analysis of the Nernst theorem as a uniform limit
We revisit the relationship between the Nernst theorem and the Kelvin-Planck
statement of the second law. We propose that the exchange of entropy uniformly
vanishes as the temperature goes to zero. The analysis of this assumption shows
that is equivalent to the fact that the compensation of a Carnot engine scales
with the absorbed heat so that the Nernst theorem should be embedded in the
statement of the second law.
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Se analiza la relaci{\'o}n entre el teorema de Nernst y el enunciado de
Kelvin-Planck del segundo principio de la termodin{\'a}mica. Se{\~n}alamos el
hecho de que el cambio de entrop{\'\i}a tiende uniformemente a cero cuando la
temperatura tiende a cero. El an{\'a}lisis de esta hip{\'o}tesis muestra que es
equivalente al hecho de que la compensaci{\'o}n de una m{\'a}quina de Carnot
escala con el calor absorbido del foco caliente, de forma que el teorema de
Nernst puede derivarse del enunciado del segundo principio.Comment: 8pp, 4 ff. Original in english. Also available translation into
spanish. Twocolumn format. RevTe
Confronting models on cosmic ray interactions with particle physics at LHC energies
Inelastic pp collisions are dominated by soft (low momentum transfer) physics
where perturbative QCD cannot be fully applied. A deep understanding of both
soft and semi-hard processes is crucial for predictions of minimum bias and
underlying events of the now coming on line pp Large Hadron Collider (LHC).
Moreover, the interaction of cosmic ray particles entering in the atmosphere is
extremely sensitive to these soft processes and consequently cannot be
formulated from first principles. Because of this, air shower analyses strongly
rely on hadronic interaction models, which extrapolate collider data several
orders of magnitude. A comparative study of Monte Carlo simulations of pp
collisions (at the LHC center-of-mass energy ~ 14 TeV) using the most popular
hadronic interaction models for ultrahigh energy cosmic ray (SIBYLL and QGSJET)
and for collider physics (the PYTHIA multiparton model) is presented. The most
relevant distributions are studied including those observables from diffractive
events with the aim of discriminating between the different models.Comment: 8 pages revtex, 8 figures, added reference
Tailoring chitosan/lta zeolite hybrid aerogels for anionic and cationic dye adsorption
Chitosan (CS) is largely employed in environmental applications as an adsorbent of anionic dyes, due to the presence in its chemical structure of amine groups that, if protonated, act as adsorbing sites for negatively charged molecules. Efficient adsorption of both cationic and anionic dyes is thus not achievable with a pristine chitosan adsorbent, but it requires the combination of two or more components. Here, we show that simultaneous adsorption of cationic and anionic dyes can be obtained by embedding Linde Type A (LTA) zeolite particles in a crosslinked CS‐based aerogel. In order to optimize dye removal ability of the hybrid aerogel, we target the crosslinker concentration so that crosslinking is mainly activated during the thermal treatment after the fast freezing of the CS/LTA mixture. The adsorption of isotherms is obtained for different CS/LTA weight ratios and for different types of anionic and cationic dyes. Irrespective of the formulation, the Langmuir model was found to accurately describe the adsorption isotherms. The optimal tradeoff in the adsorption behavior was obtained with the CS/LTA aerogel (1:1 weight ratio), for which the maximum uptake of indigo carmine (anionic dye) and rhodamine 6G (cationic dye) is 103 and 43 mg g−1, respectively. The behavior observed for the adsorption capacity and energy cannot be rationalized as a pure superposition of the two components, but suggests that reciprocal steric effects, chemical heterogeneity, and molecular interactions between CS and LTA zeolite particles play an important role
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