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271.
Augusta Molnar Denyse Gomes Romier Sousa Natalia Vidal Rene Forster Hojer Luis Alfonso Arguelles 《Journal of Sustainable Forestry》2013,32(1-2):87-121
ABSTRACT A significant shift has taken place in global forest tenure, with a doubling of the forest area under community ownership (or administration over the past 15 years). There is every indication that communal tenure will double again over the next 15 years. Recognition of traditional and indigenous peoples' collective rights over forest lands has important implications for forest-rich countries—both developed and developing. Combined with dramatic changes in the structure of the forest industry and globalizing markets, this shift creates new opportunities and challenges for low-income forest producers and community enterprises to leave poverty and diversify livelihoods. The challenge for policy makers and governments is to reform outdated regulatory and incentive frameworks to support these enterprises. This article presents findings on three types of responses from communities to the new opportunities created by the tenure shift and looks specifically at community timber enterprise cases from Mexico and Brazil; recommending actions by communities, policy makers, and private sector. Changes in international and domestic forest product demand, consolidation of commodity wood sectors, new corporate responsibility commitments, and the emergence of ecosystem service markets all affect community markets. One response has been the emergence of socially-integrated, timber and non-timber based enterprises. Another has been the expansion of self-financed community conservation. A third response has been new models of collaboration between companies and communities. 相似文献
272.
Lucy J. Bridgman Verónica V. Benitez Maricel Graña Grilli Natalia Mufato Daniela Acosta M. Laura Guichón 《Landscape Ecology》2012,27(5):633-640
Dispersal is a key element of the invasion process for introduced species, and is influenced by landscape connectivity. The
red-bellied squirrel (Callosciurus erythraeus) was introduced to Argentina in 1970. Suitable forest habitat for this arboreal species is highly fragmented in a rural–urban
matrix, but despite this, the squirrel population has spread. Squirrels disperse into new habitat patches using connective
features such as forest corridors. They may also cross gaps but up to what extent is not known. Gap crossing success is influenced
by perceptual range, which is the distance from which animals can perceive suitable habitat. Perceptual range has been previously
estimated for vulnerable species, but not for introduced species. We used a model relating perceptual range to body mass to
predict the perceptual range of the red-bellied tree squirrel in Argentina. We then tested our prediction of 202–221 m by
releasing squirrels in an unfamiliar arable field at different distances (300, 200, 100 and 20 m) from woodland habitat. We
assumed that if woodland could be perceived, squirrels would orientate toward it. We estimated perceptual range to be between
20 and 100 m, considerably lower than predicted. Our results indicate that squirrels can potentially cross small habitat gaps,
but dispersal over greater distances lacking connectivity is less likely. Incorporating this information when modelling the
spread of exotic squirrels in the Pampas Region can yield more accurate prediction of the invasion process and guide management
practices to minimise their expansion. 相似文献
273.
274.
Maldonado NC de Ruiz CS Otero MC Sesma F Nader-Macías ME 《Research in veterinary science》2012,92(2):342-349
Lactic acid bacteria (LAB) are widely used as probiotics in humans and animals to restore the ecological balance of different mucosa. They help in the physiological functions of newborn calves that are susceptible to a variety of syndromes. The criteria for the selection of strains for the design of probiotic products are not available. Based in the host-specificity of the indigenous microbiota, 96 LAB isolates from faeces and oral cavity of calves were obtained. The surface properties were screened showing a small number of highly hydrophobic or autoagglutinating isolates. Also, a group produced H(2)O(2) and were able to inhibit pathogens, and two strains were bacteriocin-producers. Some grew at very low pH and high bile concentrations. The strains sharing some of the specific properties evaluated were identified genetically, assayed their compatibility and exopolysaccharide production. The results allow going further in the establishment of criteria to select strains to be included in a multi-strain-probiotic-product to be further assayed in animals. 相似文献
275.
276.
Heavy chain antibodies (HCAbs), devoid of the light chains and the CH(1) domain, are present in the serum of camelids. IgG(2) and IgG(3) are HCAbs; whereas IgG(1) has the conventional structure. In order to study the immunological properties of llama HCAbs, from which to date little is known, llamas (Lama glama) HCAbs cDNA were cloned, sequenced and compared with other mammalian Igs. The sequence analysis showed that llama HCAbs cDNA organization is similar to other mammalian Igs and the presence of conserved binding motifs to Protein A, Protein G, FcγRI, FcγRIII and C1q in HCAbs were observed. In a previous work, different IgG isotypes purified by Protein A and Protein G chromatography, were assayed for their ability to fix complement. Both IgG(1) and the total serum were able to fix complement, whereas IgG(2) and IgG(3) fixed complement even in the absence of antigen (anti-complementary activity). Therefore, in this work we performed the complement activating activity of the different IgG isotypes purified under physiological conditions using Sephadex G-150 and their ability to induce hemagglutination. Llamas were immunized with sheep red blood cells (RBC) stroma and the different isotypes were purified from sera. Whole serum and IgG(1) could activate complement; however, HCAbs (IgG(2)+IgG(3)) could not, despite the presence of the C1q binding motif in their primary sequence. Unlike IgG(1), the fraction corresponding to IgG(2)+IgG(3) did not display hemagglutinating activity. Our findings suggest that HCAbs cannot crosslink efficiently with different antigens and that the C1q binding site might be hindered by the proximity of the variable domains. 相似文献
277.
Natalia Diez-Bru DVM PhD Isabel Garcia-Real DVM Elena M. Martinez DVM PhD Eduardo Rollan DVM PhD Ana Mayenco DVM PhD Pilar Llorens DM PhD 《Veterinary radiology & ultrasound》1998,39(3):226-233
Signalment, clinical history, physical examination, clinicopathologic, readiographic and ultrasonographic findings of 10 female dogs with histologically confirmed ovarian neoplasms were reviewed. Ultrasonographic images and reports were reviewed for (1) location, size, outer margins, and echogenicity of the mass(es), (2) presence of free abdominal fluid, (3) evidence of uterine abnormalities, and (4) signs of metastatic disease. The masses were classified according to their ultrasonographic pattern in solid, solid with cystic component, and cystic. The masses were ultrasonographically reported as being of ovarian origin in eight dogs, and this origin was included in the list of differentials in the remaining two dogs. When present, abdominal effusions and uterine abnormalities were diagnosed by means of ultrasound. 相似文献
278.
Sahar Alsaidi Nadjet Cornejal Oneil Mahoney Claudia Melo Neeharika Verma Thierry Bonnaire Theresa Chang Barry R. OKeefe James Sailer Thomas M. Zydowsky Natalia Teleshova Jos A. Fernndez Romero 《Marine drugs》2021,19(8)
Over 182 million confirmed cases of COVID-19 and more than 4 million deaths have been reported to date around the world. It is essential to identify broad-spectrum antiviral agents that may prevent or treat infections by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but also by other coronaviruses that may jump the species barrier in the future. We evaluated the antiviral selectivity of griffithsin and sulfated and non-sulfated polysaccharides against SARS-CoV-1 and SARS-CoV-2 using a cytotoxicity assay and a cell-based pseudoviral model. The half-maximal cytotoxic concentration (CC50) and half-maximal effective concentration (EC50) were determined for each compound, using a dose-response-inhibition analysis on GraphPad Prism v9.0.2 software (San Diego, CA, USA). The therapeutic index (TI = CC50/EC50) was calculated for each compound. The potential synergistic, additive, or antagonistic effect of different compound combinations was determined by CalcuSyn v1 software (Biosoft, Cambridge, UK), which estimated the combination index (CI) values. Iota and lambda carrageenan showed the most potent antiviral activity (EC50 between 3.2 and 7.5 µg/mL). Carrageenan and griffithsin combinations exhibited synergistic activity (EC50 between 0.2 and 3.8 µg/mL; combination index <1), including against recent SARS-CoV-2 mutations. The griffithsin and carrageenan combination is a promising candidate to prevent or treat infections by SARS-CoV-1 and SARS-CoV-2. 相似文献
279.
Tree cavities play a critical role in the life history of cavity-using species and thus are an important structural feature of forests. Furthermore, some common forest management practices can have a profound negative effect on cavity quantity and quality. This is the first study to address cavity resources in Neotropical montane forests and with this information we hope to develop approaches to sustainable forest management that will assure the conservation of cavity nesters. Our study design consisted of two treatments (control and harvested forest) in both piedmont and cloud forests of the subtropical montane forests of the Andes. This study indicates that cavities are an uncommon feature even in control sites with only 3% of the trees harboring cavities in both forest types. Even more uncommon are potentially usable cavities for avian cavity nesters: only 0.15% of the trees have a potentially usable cavity in the piedmont forest and only 0.42% in the cloud forest. In logged forests there is a significantly lower density of potentially usable cavities (4.12 vs. 0.51 cavities/ha in piedmont forest and 3.91 vs. 1.64 cavities/ha in the cloud forest). Furthermore, we documented a high loss rate of potentially usable cavities (from 23 to 40%/year) that differs between tree species and DBH classes. More specifically, in the piedmont forest, large, decaying Calycophyllum multiflorum have a relatively greater probability of having potentially usable cavities, while in the cloud forest potentially usable cavities are disproportionably found in large, decaying Blepharocalyx gigantea. In both forest types, snags are also very likely to harbor a potentially usable cavity. In order for harvested stands in the subtropical montane forest of the Andes to regain some of their ecological value, it is necessary to retain trees that have potentially usable cavities and also trees with the highest probability of becoming usable cavity trees. 相似文献
280.
Remote sensing of soybean canopy as a tool to map high pH, calcareous soils at field scale 总被引:1,自引:0,他引:1
Soybean (Glycine max Merr.) is extensively grown in areas of the US Corn Belt where soils often range from relatively acid (pH < 6) to alkaline,
calcareous. Iron availability decreases with increase in pH, consequently, soybean can suffer from iron deficiency chlorosis
on high pH, calcareous areas of the field. The extent of those areas sometimes can be significant, but they often occur in
complex and discontinuous patterns. The objective of the research was to explore how remote sensing of soybean canopies and
GIS technologies could be used to map and quantitatively describe the extent of high pH, calcareous soils at field scale.
Aerial images that consisted of visible red, green, blue, and near infrared bands were used to calculate green normalized
difference vegetative index (GNDVI) and to guide plant and soil sampling at 10 fields during 2003 and 2004 growing seasons.
Ten to 18 sampling areas were selected on each field to include a wide range in GNDVI values. Soil samples were analyzed for
pH and calcium carbonate equivalent (CCE). Plant samples were used to estimate grain yields. Soil pH and CCE were significantly
correlated with GNDVI values in eight and seven sites, respectively. A previously developed alkalinity stress index (ASI),
which combines pH and CCE in one value, was significantly related to GNDVI at all 10 sites. Remote sensing of soybean canopy
was shown to be a promising tool that can be used to quantitatively describe distribution of alkaline soils at field scale. 相似文献