939 resultados para compression wood


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Summary

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The banding pattern (G-, C-, AgNOR-staining) was described in karyotypes of Apodemus alpicola Heinrich, 1952 and A. microps Kratochvil et Rosicky, 1952 collected from the Alps and central Europe, Distinct differences between the two species were revealed in the distribution of C-heterochromatic regions in autosomes and the sex chromosomes, and the distribution of nucleolar organizer regions (NORs). Extensive variation in the distribution pattern of C-heterochromatin and NORs obviously exists among the wood mice of the subgenus Sylvaemus, and individual species can be distinguished according to a specific variation pattern. However, it seems premature to designate individual karyotypic forms as separate species, because the extent of overall geographical interpopulation variation is still not sufficiently known.

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ABSTRACT The impact of intensive management practices on the sustainability of forest production depends on maintenance of soil fertility. The contribution of forest residues and nutrient cycling in this process is critical. A 16-year-old stand of Pinus taeda in a Cambissolo Húmico Alumínico léptico (Humic Endo-lithic Dystrudept) in the south of Brazil was studied. A total of 10 trees were sampled distributed in five diameter classes according to diameter at breast height. The biomass of the needles, twigs, bark, wood, and roots was measured for each tree. In addition to plant biomass, accumulated plant litter was sampled, and soil samples were taken at three increments based on sampling depth: 0.00-0.20, 0.20-0.40, 0.40-0.60, 0.60-1.00, 1.00-1.40, 1.40-1.80, and 1.80-1.90 m. The quantity and concentration of nutrients, as well as mineralogical characteristics, were determined for each soil sample. Three scenarios of harvesting intensities were simulated: wood removal (A), wood and bark removal (B), and wood + bark + canopy removal (C). The sum of all biomass components was 313 Mg ha-1.The stocks of nutrients in the trees decreased in the order N>Ca>K>S>Mg>P. The mineralogy of the Cambissolo Húmico Alumínico léptico showed the predominance of quartz sand and small traces of vermiculite in the silt fraction. Clay is the main fraction that contributes to soil weathering, due to the transformation of illite-vermiculite, releasing K. The depletion of nutrients from the soil biomass was in the order: P>S>N>K>Mg>Ca. Phosphorus and S were the most limiting in scenario A due to their low stock in the soil. In scenario B, the number of forest rotations was limited by N, K, and S. Scenario C showed the greatest reduction in productivity, allowing only two rotations before P limitation. It is therefore apparent that there may be a difference of up to 30 years in the capacity of the soil to support a scenario such as A, with a low nutrient removal, compared to scenario C, with a high nutrient removal. Hence, the effect of different harvesting intensities on nutrient availability may jeopardize the sustainability of P. taeda in the short-term.

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Data sheet produced by the Iowa Department of Natural Resources is about different times of animals, insects, snakes, birds, fish, butterflies, etc. that can be found in Iowa.

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The Formica rufa group (red wood ants) currently includes six species. Nevertheless, during previous work based on molecular markers, we showed the existence of one population morphologically identified as F. lugubris, but genetically different from all other analysed populations of this species. This population could represent a cryptic species within the Swiss National Park and has been provisionally named Formica lugubris-A2. To verify our hypothesis, we conducted a behavioural test based on the ability of ants to recognize pupae of their own species when compared to those of another species. The three red wood ant species present in the Swiss National Park (F. lugubris, F. paralugubris and F. aquilonia) and the F. lugubris-A2 population were used in our study. Results indicate that the F. lugubris-A2 population differs from other F. lugubris and from all other species in the behaviour of its workers and in the way its pupae are discriminated by other species. This is in accordance with the genetic data and strengthens our hypothesis on the existence of a new cryptic red wood ant species within the Swiss National Park.

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Background: Excessive mediastinal shift into the vacated thoracic cavity after pneumonectomy can result in dyspnea without hypoxemia by compression of the tracheobronchial tree, a phenomenon called postpneumonectomy syndrome. More rarely hypoxemia in upright position (platypnea-orthodeoxia syndrome, POS) after pneumonectomy can result from re-opening of an atrial right-to-left shunt through a patent foramen ovale (PFO) due to mediastinal distorsion. Review of literature also shows a unique report of pulmonary veins stenosis resulting in POS without intracardiac shunt after pneumonectomy. Methods: We report the case of a 32-year-old woman who presented POS 6 months after right pneumonectomy for destroyed lung post tuberculosis. Results: The patient described severe dyspnea disappearing when lying. SpO2 decreased from 94% when lying to 60% sitting. Transthoracic echocardiography (TTE) suspected a possible PFO. We first tried to highlight clinical repercussions of PFO by noninvasive exams. Hyperoxia shunt quantification was not tolerated because of increased dyspnea in sitting position. Contrast bubbles TTE was difficult because of the important mediastinal shift but identified only rare left heart bubbles with/without Valsalva both in lying and sitting position, excluding a significant right-to-left shunt. A lung perfusion scintigraphy (injection while sitting) confirmed the absence of systemic isotope uptake. Computed tomographic pulmonary angiography (angio-CT) revealed a stretched but not stenosed left main bronchus, while the shift of the heart into the right cavity was major. Pulmonary angiography did not show embolism but revealed compression of the inferior vena cava (IVC) with impaired venous return to the right heart, as well as compression of the left pulmonary veins. There was no arteriovenous shunt. Cardiac MRI showed torsion of IVC at the level of the diaphragm, and strong atrial contraction contributing to a passive filling of the RV, while the right ventricle was normal. Right catheterism showed major hemodynamic disturbances with negative diastolic pressure in right heart cavities (atrium -12 mm Hg ventricle pressure -7 mm Hg). SaO2 measured in the pulmonary artery decreased from 58% when lying to 45% sitting. Conclusion: We described here an exceedingly rare and complex mechanism explaining POS after right pneumonectomy. Mediastinal repositioning with a silicone breast implant of appropriate size has been scheduled.