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Search Results: 1 - 10 of 4024 matches for " Caroline Vasicek Gaugris "
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A Step Closer to Local Carbon Calculations: Growth Timescales and Linear Relationships for Sand Forest and Woodland Tree Species in Maputaland, South Africa  [PDF]
Jerome Gaugris, Caroline A. Vasicek
Open Journal of Forestry (OJF) , 2014, DOI: 10.4236/ojf.2014.43029

In Africa, information on time required for plants to develop from seed to mean size and maximum size is scarce. There is also a lack of information regarding accurate relationships between stem diameter, height and canopy dimensions. This type of information is however becoming a real necessity to allow the accurate measurement of carbon stocks and carbon stocks change to qualify for the UNFCCC’s REDD+ mechanism. We evaluated these parameters for 22 Sand Forest and woodland tree species of South Africa’s Maputaland. Results indicated that it takes approximately 66 and 35 years for current dynamics of Sand Forests and woodlands to occur respectively. Based on diameter and growth rates, larger trees of the forests can be older than 600 years, while large woodland trees can reach ages of 900 years. Our evaluation of linear relationships between stem diameter, height and canopy dimensions showed extremely robust results allowing the use of stem diameter to calculate height and canopy dimensions. The results are of interest for carbon related investigations and reconstructing stands dynamics.

Floristic Composition, Diversity and Structure of the Rainforest in the Mayoko District, Republic of Congo  [PDF]
Margaretha W. van Rooyen, Noel van Rooyen, Edmond S. Miabangana, Gilbert Nsongola, Caroline Vasicek Gaugris, Jér?me Y. Gaugris
Open Journal of Forestry (OJF) , 2019, DOI: 10.4236/ojf.2019.91002
Abstract: Botanically, the Mayoko district is known only through anecdotal descriptions made in the colonial era. The present study was undertaken as part of the prerequisite for a mining feasibility study where a benchmark of the floristic composition, diversity and structure of the vegetation was needed to evaluate potential biodiversity offset areas and to guide species selection for post-mining re-vegetation. The study area comprised approximately 160,000 ha and 235 sample sites were surveyed using the Braun-Blanquet method of phytosociology. Diversity of each plant association was expressed in terms of various diversity parameters. Twelve associations were described and mapped. The associations ranged from highly disturbed and degraded to fairly intact forest associations. A wet to dry gradient and permanently inundated to temporary inundated gradient could also be distinguished. The approach followed here proved remarkably robust in illustrating the complexity in a topographically complex region of the Chaillu Massif. The data provided a high level of insight into the possible dynamics of the rainforest and indications as to possible successional pathways. This information provides a better level of understanding of forest structure and evolution potential than studies limited to trees, remote sensing carbon assessments, or time change series.
New chitinozoan species from the Devonian of the Paraná Basin, south Brazil, and their biostratigraphic significance
Gaugris,Kariny De Amorim; Grahn,Yngve;
Ameghiniana , 2006,
Abstract: devonian chitinozoans from two wells in the north-northwestern outcrop belt of the paraná basin, and three in the eastern outcrop belt of the same basin, have been investigated for this study. a new, hitherto undescribed chitinozoan assemblage of early devonian, pre-late emsian age is recognized above the ramochitina magnifica lange interval range zone, in addition to new species from younger devonian beds. a new early devonian biozone, the ancyrochitina pachycerata interval range zone, is erected. altogether, 16 new species are described of which 10 are left in open nomenclature due to insufficient number of well-preserved specimens. the biostratigraphy of the new chitinozoan species is compared with the chitinozoa and miospore zones previously recognized in the paraná basin, and to standard conodont zonation.
Monotone measures of ergodicity for Markov chains
J. Keilson,O. A. Vasicek
International Journal of Stochastic Analysis , 1998, DOI: 10.1155/s1048953398000239
Abstract: The following paper, first written in 1974, was never published other than as part of an internal research series. Its lack of publication is unrelated to the merits of the paper and the paper is of current importance by virtue of its relation to the relaxation time. A systematic discussion is provided of the approach of a finite Markov chain to ergodicity by proving the monotonicity of an important set of norms, each measures of egodicity, whether or not time reversibility is present. The paper is of particular interest because the discussion of the relaxation time of a finite Markov chain [2] has only been clean for time reversible chains, a small subset of the chains of interest. This restriction is not present here. Indeed, a new relaxation time quoted quantifies the relaxation time for all finite ergodic chains (cf. the discussion of Q1(t) below Equation (1.7)]. This relaxation time was developed by Keilson with A. Roy in his thesis [6], yet to be published.
Vasicek,Araceli; La Rossa,Francisco; Paglioni,Andrea;
Agricultura Técnica , 2000, DOI: 10.4067/S0365-28072000000400004
Abstract: in the present work, biological and population parameters of aphid nasonovia ribisnigri on lettuce (lactuca sativa l.) varieties divina, criolla blanca and cuatro estaciones, were obtained and compared. cohorts were reared at 10± 1oc; 14:10 l:d cycle and 90% of relative humidity. nimphal period was longest on criolla blanca varying between 31 and 34 days, while on the rest of cultivars the length of this period was 22 to 25 days. reproductive period and fecundity were also higher on criolla blanca. net reproductive rate (ro) values were 12.70 to 22.35 female/female on criolla blanca. on cuatro estaciones and divina, ro values were 6.85 to 9.95 and 5.80 to 8.56, respectively. significant differences among the values of intrinsic rate of increase (rm) calculated for each variety were observed. cohorts on criolla blanca showed the highest values of rm with 0.066 to 0.081, followed by cuatro estaciones (0.041-0.049) and divina (0.046-0.055). survivorship (lx) and fecundity (mx) curves were also analyzed. results indicate that cuatro estaciones and divina could have some negative effect on the population increase of n. ribisnigri, compared with criolla blanca
ASPECTOS BIOLOGICOS Y POBLACIONALES DE Nasonovia ribisnigri (Mosley) (HOMOPTERA: APHIDOIDEA) EN TRES VARIEDADES COMERCIALES DE LECHUGA (Lactuca sativa L.) EN CONDICIONES DE LABORATORIO Biological and populational aspects of Nasonovia ribisnigri (Mosley) (Homoptera: Aphidoidea) on three commercial varieties of lettuce (Lactuca sativa L.) under laboratory conditions
Araceli Vasicek,Francisco La Rossa,Andrea Paglioni
Agricultura Técnica , 2000,
Abstract: En el presente trabajo se determinaron y compararon los principales parámetros biológicos y poblacionales del áfido Nasonovia ribisnigri sobre las variedades de lechuga (Lactuca sativa L.) Divina, Criolla Blanca y Cuatro Estaciones. Las cohortes fueron criadas a 10± 1oC; 14:10 horas (fotofase: escotofase) y aproximadamente 90 % de humedad relativa. El período ninfal fue más largo sobre Criolla Blanca, oscilando entre 31 y 34 días, mientras que en las restantes duró entre 22 y 25 días. La duración del período reproductivo y la fecundidad fueron también mayores en Criolla Blanca. Los valores de la tasa de reemplazo (Ro) variaron entre 12,70 y 22,35 hembra/hembra para Criolla Blanca. En las variedades Cuatro Estaciones y Divina, dicho parámetro fue de 6,85 a 9,95 y 5,80 a 8,56, respectivamente. Se observaron diferencias significativas entre los valores de la tasa intrínseca de crecimiento (r m) y otros parámetros relacionados calculados para cada variedad. Las cohortes criadas sobre Criolla Blanca mostraron los más altos valores de r m con 0,066 a 0,081, seguidas por aquellas en Cuatro Estaciones (0,041-0,049) y Divina (0,046-0,055). Se analizaron también las curvas de supervivencia (l x) y fecundidad (m x). Los resultados indican que el cultivar Cuatro Estaciones y Divina podrían tener algún efecto negativo sobre el incremento poblacional de N. ribisnigri en comparación con Criolla Blanca In the present work, biological and population parameters of aphid Nasonovia ribisnigri on lettuce (Lactuca sativa L.) varieties Divina, Criolla Blanca and Cuatro Estaciones, were obtained and compared. Cohorts were reared at 10± 1oC; 14:10 L:D cycle and 90% of relative humidity. Nimphal period was longest on Criolla Blanca varying between 31 and 34 days, while on the rest of cultivars the length of this period was 22 to 25 days. Reproductive period and fecundity were also higher on Criolla Blanca. Net reproductive rate (Ro) values were 12.70 to 22.35 female/female on Criolla Blanca. On Cuatro Estaciones and Divina, Ro values were 6.85 to 9.95 and 5.80 to 8.56, respectively. Significant differences among the values of intrinsic rate of increase (r m) calculated for each variety were observed. Cohorts on Criolla Blanca showed the highest values of r m with 0.066 to 0.081, followed by Cuatro Estaciones (0.041-0.049) and Divina (0.046-0.055). Survivorship (l x) and fecundity (m x) curves were also analyzed. Results indicate that Cuatro Estaciones and Divina could have some negative effect on the population increase of N. ribisnigri, compared with Criolla Blanca
Kelvin Notation for Stabilizing Elastic-Constant Inversion Notation Kelvin pour stabiliser l'inversion de constantes élastiques
Dellinger J.,Vasicek D.,Sondergeld C.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1998063
Abstract: Inverting a set of core-sample traveltime measurements for a complete set of 21 elastic constants is a difficult problem. If the 21 elastic constants are directly used as the inversion parameters, a few bad measurements or an unfortunate starting guess may result in the inversion converging to a physically impossible solution . Even given perfect data, multiple solutions may exist that predict the observed traveltimes equally well. We desire the inversion algorithm to converge not just to a physically possible solution, but to the best(i. e. most physically likely) solution of all those allowed. We present a new parameterization that attempts to solve these difficulties. The search space is limited to physically realizable media by making use of the Kelvin eigenstiffness-eigentensor representation of the 6 x 6 elastic stiffness matrix. Instead of 21 stiffnesses, there are 6 eigenstiffness parametersand 15 rotational parameters . The rotational parameters are defined using a Lie-algebra representation that avoids the artificial degeneracies and coordinate-system bias that can occur with standard polar representations. For any choice of these 21 real parameters, the corresponding stiffness matrix is guaranteed to be physically realizable. Furthermore, all physically realizable matrices can be represented in this way. This new parameterization still leaves considerable latitude as to which linear combinations of the Kelvin parameters to use, and how they should be ordered. We demonstrate that by careful choice and ordering of the parameters, the inversion can be relaxedfrom higher to lower symmetry simply by adding a few more parameters at a time. By starting from isotropy and relaxing to the general result in stages (isotropy, transverse isotropy, orthorhombic, general), we expect that the method should find the solution that is closest to isotropy of all those that fit the data. L'inversion d'un ensemble de mesures du temps de parcours d'une carotte-échantillon pour la détermination d'un groupe complet de 21 constantes élastiques est un problème difficile. Si nous utilisons directement les 21 constantes élastiques comme paramètres d'inversion, quelques mesures incorrectes ou une malheureuse hypothèse de départ, peuvent faire que l'inversion aboutit à une solution physiquement impossible. Même en disposant de données parfaites, de multiples solutions peuvent expliquer les temps de parcours observés. Notre objectif est de faire en sorte que l'algorithme d'inversion donne non seulement une solution physiquement possible, mais la meilleuresolution (autrement
Vasicek,Araceli; La Rossa,Francisco; Paglioni,Andrea; Fostel,Luis;
Agricultura Técnica , 2003, DOI: 10.4067/S0365-28072003000100002
Abstract: cohorts of myzus persicae (sulzer) were reared on raphanus sativus, brassica oleracea var. capitata and b. oleracea var. italica at 10 ± 1oc, 90% relative humidity and a 12:12 h photoperiod. under these conditions significant statistical differences were found between intrinsic growth rates (rm), which reached a maximum of 0.082, 0.045 and 0.028 females female-1 d-1 on r. sativus, b. oleraceea var. italica and b. oleracea var. capitata, respectively, and net reproductive rates (ro) were 26, 6 and 3.4 females female-1 generation-1, respectively. m. persicae needs ca. around 8 days to duplicate numbers (d) on r. sativus and 16 and 30 days on b. oleracea var. italica and b. oleracea var. capitata, respectively. results indicated this the aphid could reach greater population levels on r. sativus than on the other cruciferous plants during the fall and winter seasons, and an intercrop cultivation with other cruciferous plants could be recommended if it is the main crop. on the other hand, r. sativus is a winter weed for other vegetable crops, and thus early control could reduce posterior dispersion of the aphid.
Primer registro de Greenidea ficicola Takahashi (Hemiptera: Aphididae) en Argentina
La Rossa,Francisco R.; Vasicek,Araceli L.; Paglioni,Andrea;
Revista de la Facultad de Ciencias Agrarias. Universidad Nacional de Cuyo , 2011,
Abstract: greenidea ficicola takahashi is reported for the first time in argentina. this aphid was found on ficus benjamina cv variegata at la plata, buenos aires, argentina, on october 2009. the viviparous apterous female is described and illustrated.
Aspectos biológicos y poblacionales de Nasonovia ribisnigri y Aulacorthum solani sobre lechuga
Vasicek, Araceli;La Rossa, Rubén;Paglioni, Andrea;
Pesquisa Agropecuária Brasileira , 2002, DOI: 10.1590/S0100-204X2002000300023
Abstract: the influence of cultivars, criolla blanca, cuatro estaciones and gallega on the biology and the populational parameters of nasonovia ribisnigri and aulacorthum solani (l) (homoptera: aphidoidea) was considered at 10±1oc and 90% rh. the nimphal, pre-reproductive and post-reproductive periods of n. ribisnigri on cuatro estaciones were the longest but not so the reproductive. in a. solani the nimphal period was longer on criolla blanca and cuatro estaciones and as a result the reproductive was longer on cuatro estaciones. the intrinsic rates of increase (rm) of n. ribisnigri and a. solani were longer on criolla blanca and gallega, respectively. according to the predominant species it would be suitable to use cuatro estaciones for n. ribisnigri and criolla blanca for a. solani in cold times.
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