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1

Crystal structure and spectroscopic properties of Na2K6(VO)(2)(SO4)7  

DEFF Research Database (Denmark)

Red-brown crystals of a new mixed alkali oxo sulfato vanadium(V) compound Na2K6(VO)(2)(SO4)(7), suitable for X-ray determination, have been obtained from the catalytically important binary molten salt system M2S2O7-V2O5 (M = 80% K and 20% Na). By slow cooling of a mixture with the mole fraction X-V2O5 = 0.24 from 325 degreesC, i.e., just below the liquidus temperature, to the solidus temperature of around 300 degreesC, a dark reddish amorphous phase was obtained containing crystals of the earlier described V(V)-V(IV) mixed valence compound K-6(VO)(4)(SO4)(8) and Na2K6-(VO)(2)(SO4)(7) described here. This compound crystallizes in the tetragonal space group P4(3)2(1)2 (No. 96) with a = 9.540(3) Angstrom, c = 29.551(5) Angstrom at 20 degreesC and Z = 4. It contains a distorted VO6 octahedron with a short V-O bond of 1.552(6) Angstrom, a long one of 2.276(5) Angstrom trans to this, and four equatorial V-O bonds in the range 1.881(6)-1.960-(6) A. The deformation of the VO6 octahedron is less pronounced compared tothat of the known oxo sulfato V(V) compounds. Each VO3+ group is coordinated to five sulfate groups of which two are unidentately coordinated and three are bidentate bridging to neighboring VO3+ groups. The length of the S-O bonds in the S-O-V bridges of the two unidentately coordinated sulfato groups are 1.551(6) Angstrom and 1.568(6) Angstrom, respectively, which are unusually long compared to our earlier measurements of sulfate groups in other V(111), V(IV), and V(V) compounds.

Karydis, D.A.; Boghosian, S.

2002-01-01

2

Photoluminescence properties of NaSr(P, V)O4:Eu3+ phosphors.  

UK PubMed Central (United Kingdom)

Eu3+ activated NaSr(P,V)O4 phosphors have been synthesized using solid state reaction method and further characterized for their structure and optical properties using different techniques such as X-ray diffraction, scanning electron microscopy, photolumniscenec excitation, emission, and chromaticity coorrdinate analysis, etc. Material shows a broad excitation peak (monitored for lambda(ems) = 613 nm) lying in the 300-360 nm region and gives intense transitions (lambda(exc) = 320 nm) namely 5D0 --> 7F1 at 590 nm, 5D0 --> 7F2 at 613 nm, 5D0 --> 7F3 at 650 nm, and 5D0 --> 7F4 at 700 nm due to Eu3+ ion. Our results show that replacement of the PO4(3-) ions with isomorphic VO4(3-) ions improves the structural stability and the overall intensity of the emission. The maxium emission intensity is achieved for the NaSr(P0.4, V0.6)O4:Eu3+ phosphor. An estimated increase of an order is attained for the NaSr(P0.4, V0.6)O4:Eu3+ phosphor as compared to NaSrPO4:Eu3+ or NaSrVO4:Eu3+ phosphor. The chromaticity coordinate of the phosphor (0.68, 0.31) lies well within the red region and suggest that the material could be an alternative red phosphor for lighting and display applications.

Lee DG; Singh SK; Moon CH; Yi SS; Jang K; Shin DS; Jeong JH; Bae JS

2013-08-01

3

The investigation on NaVO{sub 3}-NaHCO{sub 3}-H{sub 2}O system  

Energy Technology Data Exchange (ETDEWEB)

The solubility of sodium vanadate and sodium bicarbonate in the NaVO{sub 3}-NaHCO{sub 3}-H{sub 2}O system has been investigated at 293-323 K. On the base of the obtained results a polythermal section of the system has been drawn. The change of mutual salt concentrations (in mol/dm{sup 3}) with temperature has been described with appropriate mathematical equations. Also, the equations describing the dependence of density of the solutions on temperature, have been presented. (author). 9 refs, 1 fig., 1 tab.

Trypuc, M.; Kielkowska, U. [Uniwersytet Mikolaja Kopernika, Torun (Poland). Inst. Chemii

1995-12-31

4

Vanadates of calcium and strontium in the systems NaVO3-CaCl2-MaOH-H2O, NaVO3-Sr(NO3)2-NaOH-H2O  

International Nuclear Information System (INIS)

Using pH potentiometry NaVO3 interaction with NaOH in aqueous solutions in the presence of calcium or strontium salts is investigated. Solid phases are identified by chemical and X-ray phase analyses. It is stated that SrOxV2O5x4H2O, 2CaOxV2O5x2H2O, 2SrOxV2O5x1.5H2O, 3.5CaOxV2O5, 3.5SrOxV2O5 are difficultly soluble interaction products

1987-01-01

5

Cinética do VO2 durante o exercício realizado na potência crítica em ciclistas e indivíduos não-treinados no ciclismo/ VO2 Kinetics during exercise performed at critical power in cyclists and untrained individuals  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O objetivo foi analisar a cinética do consumo de oxigênio (VO2) na potência crítica (PC), em indivíduos com diferentes níveis de aptidão aeróbia no ciclismo. Seis ciclistas treinados (GT) e sete indivíduos não-treinados (GNT) realizaram os seguintes protocolos em cicloergômetro: (a) progressivo até a exaustão para determinação do VO2max e sua respectiva intensidade (IVO2max); (b) três testes em cargas constantes até a exaustão a 95-110%IVO2max para deter (more) minação da PC; e (c) um teste em carga constante até a exaustão a 100%PC. No exercício a 100%PC, o componente lento expresso em valor absoluto (GT: 342,4±165,8 ml.min-1 vs. GNT: 571,3±170,1 ml.min-1) e relativo ao aumento do VO2 em exercício (GT: 10,0±4,6% vs. GNT: 26,6±7,3%) foram menores para GT. O VO2 ao final do exercício (GT: 89,8±8,4%VO2max vs. GNT: 97,4±2,8%VO2max) foi significativamente menor no grupo GT (? = 0,045), sendo similar ao VO2max no grupo GNT. Portanto, o nível de aptidão aeróbia pode influenciar as respostas do VO2 ao exercício em PC. Abstract in english The objective was to analyze the oxygen uptake (VO2) kinetics during exercise performed at critical power (CP) in subjects with different aerobic status in cycling. Six trained cyclists (GT) and seven non-trained subjects (GNT) underwent to the following protocols in cyclergometer: (a) incremental to exhaustion to determine VO2max and its respective workload (IVO2max); b) three square-wave tests to exhaustion at 95-110% IVO2max to determine CP, and; (c) one square-wave te (more) st to exhaustion at 100%CP. During the exercise at CP the slow component expressed as absolute value (GT: 342.4±165.8 ml.min-1 vs. GNT: 571.3±170.1 ml.min-1) and as the relative contribution to the increase of VO2 during exercise (GT: 10.0±4.6% vs. GNT: 26.6±7.3%) were lower for trained subjects. The VO2 at the end of the exercise at PC (GT: 89.8±8.4%VO2max vs. GNT: 97.4±2.8%VO2max) was significantly lower in GT (? = 0.045), and similar to VO2max in GNT. Therefore, the aerobic level might influence the VO2 responses to exercise at PC.

Caritá, Renato Aparecido Corrêa; Greco, Camila Coelho; Pessôa Filho, Dalton Müller

2013-06-01

6

Relação entre modificações cinemáticas da corrida e o tempo limite na vVO2máx/ Relationship between running kinematic changes and time limit at vVO2max  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A corrida realizada na velocidade do consumo máximo de oxigênio (vVO2máx) pode ocasionar modificações nos parâmetros cinemáticos e assim, aumentar o custo energético ao longo do tempo. O objetivo do presente estudo foi analisar características cinemáticas da articulação do tornozelo e joelho durante a corrida na vVO2máx e a relação entre modificações cinemáticas e o tempo limite na vVO2máx(Tlim). Onze voluntários ativos fisicamente foram submetidos a u (more) m teste incremental de corrida para determinar a vVO2máx e posteriormente, a um teste de velocidade constante na vVO2máx. As variáveis cinemáticas foram adquiridas através de filmagem bidimensional a 210Hz no plano sagital esquerdo, no estágio inicial e final da corrida. De todas as variáveis angulares analisadas, a máxima plantiflexão no balanço (p Abstract in english Exhaustive running at maximal oxygen uptake velocity (vVO2max) can alter running kinematic parameters and increase energy cost along the time. The aims of the present study were to compare characteristics of ankle and knee kinematics during running at vVO2max and to verify the relationship between changes in kinematic variables and time limit (Tlim). Eleven male volunteers, recreational players of team sports, performed an incremental running test until volitional exhaust (more) ion to determine vVO2max and a constant velocity test at vVO2max. Subjects were filmed continuously from the left sagittal plane at 210 Hz for further kinematic analysis. The maximal plantar flexion during swing (p

De Lucca, Leonardo; Melo, Sebastião Iberes Lopes

2012-01-01

7

Reprodutibilidade do VO2Máx estimado na corrida pela frequência cardíaca e consumo de oxigênio de reserva/ Reliability of VO2Max estimated in treadmill running by heart rate reserve and power output  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Objetivou-se comparar os efeitos de utilização da frequência cardíaca máxima medida (FCpico) vs. predita (FC Predita) na estimativa do VO2Máx em esteira pelo método de FC e VO2 de reserva. Dezoito homens (27,5 ± 7,1 anos, 73,7 ± 12,6 kg, 174,8 ± 10,2 cm) realizaram na primeira visita um teste progressivo máximo para determinar a FCpico. Nas duas visitas seguintes foram realizados os testes aeróbios submáximos em esteira com estágio de 6 min a 75% da FC de re (more) serva. O VO2Máx foi estimado pelo uso conjunto das equações de FC, VO2 de reserva e equação de corrida do ACSM. Não foi observada diferença significativa (teste t) entre as estimativas de VO2Máx a partir da FCpredita e FCpico. O coeficiente de correlação intraclasse e erro típico da medida utilizando FCpredita e FCpico foram 0,89, 2,43 mL.kg-1.min-1 (5%) e 0,83, 2,43 mL.kg-1.min-1 (4,9%), respectivamente. O uso da abordagem estimada para determinação da FC máxima mostrou-se adequado para a determinação do VO2Máx com um pequeno erro típico da medida. Abstract in english The objective was to determine the reliability of the VO2Max estimate on a treadmill using the measured (HRpeak) vs. the predicted (HRpredicted) maximum heart rate (HR). Eighteen men (27.5 ± 7.1 years, 73.7± 12.6 kg, 174.8 ± 10.2 cm) performed, in the first visit, a progressive test to determine the HRpeak. In the two following visits, submaximal aerobic tests were performed on a treadmill with a 6 min at 75% HR reserve. VO2Max was estimated by means of the equations o (more) f HR, VO2 reserve and the ACSM running equation. The intraclass correlation coefficient and the typical error of measurement using HRPredicted and HRpeak were 0.89, 2.43 ml.kg-1.min-1 (5%) and 0.83, 2.43 mL.kg-1.min-1 (4.9%), respectively. There was no significant difference (t test) between the estimates of VO2Max from the HRpeak and HRpredicted. The use of the HRpredicted was considered appropriate for VO2Max estimation, with a small typical error of measurement.

Santos, Tony Meireles; Viana, Bruno Ferreira; Sá Filho, Alberto Souza

2012-03-01

8

Reprodutibilidade do VO2Máx estimado na corrida pela frequência cardíaca e consumo de oxigênio de reserva Reliability of VO2Max estimated in treadmill running by heart rate reserve and power output  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivou-se comparar os efeitos de utilização da frequência cardíaca máxima medida (FCpico) vs. predita (FC Predita) na estimativa do VO2Máx em esteira pelo método de FC e VO2 de reserva. Dezoito homens (27,5 ± 7,1 anos, 73,7 ± 12,6 kg, 174,8 ± 10,2 cm) realizaram na primeira visita um teste progressivo máximo para determinar a FCpico. Nas duas visitas seguintes foram realizados os testes aeróbios submáximos em esteira com estágio de 6 min a 75% da FC de reserva. O VO2Máx foi estimado pelo uso conjunto das equações de FC, VO2 de reserva e equação de corrida do ACSM. Não foi observada diferença significativa (teste t) entre as estimativas de VO2Máx a partir da FCpredita e FCpico. O coeficiente de correlação intraclasse e erro típico da medida utilizando FCpredita e FCpico foram 0,89, 2,43 mL.kg-1.min-1 (5%) e 0,83, 2,43 mL.kg-1.min-1 (4,9%), respectivamente. O uso da abordagem estimada para determinação da FC máxima mostrou-se adequado para a determinação do VO2Máx com um pequeno erro típico da medida.The objective was to determine the reliability of the VO2Max estimate on a treadmill using the measured (HRpeak) vs. the predicted (HRpredicted) maximum heart rate (HR). Eighteen men (27.5 ± 7.1 years, 73.7± 12.6 kg, 174.8 ± 10.2 cm) performed, in the first visit, a progressive test to determine the HRpeak. In the two following visits, submaximal aerobic tests were performed on a treadmill with a 6 min at 75% HR reserve. VO2Max was estimated by means of the equations of HR, VO2 reserve and the ACSM running equation. The intraclass correlation coefficient and the typical error of measurement using HRPredicted and HRpeak were 0.89, 2.43 ml.kg-1.min-1 (5%) and 0.83, 2.43 mL.kg-1.min-1 (4.9%), respectively. There was no significant difference (t test) between the estimates of VO2Max from the HRpeak and HRpredicted. The use of the HRpredicted was considered appropriate for VO2Max estimation, with a small typical error of measurement.

Tony Meireles Santos; Bruno Ferreira Viana; Alberto Souza Sá Filho

2012-01-01

9

Efeitos do estado e especificidade do treinamento aeróbio na relação %VO2max versus %FCmax durante o ciclismo/ Effects of the state and specificity of aerobic training on the %VO2max versus %HRmax ratio during cycling  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese OBJETIVO: Determinar os efeitos do estado e especificidade de treinamento aeróbio na relação entre o percentual do consumo máximo de oxigênio (%VO2max) e o percentual da frequência cardíaca máxima (%FCmax) durante o exercício incremental realizado no cicloergômetro. MÉTODOS: Sete corredores, 9 ciclistas, 11 triatletas e 12 sedentários, todos do sexo masculino e aparentemente saudáveis, foram submetidos a um teste incremental até a exaustão no cicloergômetr (more) o. Regressões lineares entre %VO2max e %FCmax foram determinadas para cada indivíduo. Com base nessas regressões, foram calculados %FCmax correspondentes a determinados %VO2max (50, 60, 70, 80 e 90%) de cada participante. RESULTADOS: Não foram encontradas diferenças significantes entre todos os grupos nos %FCmax para cada um dos %VO2max avaliados. Analisando-se os voluntários como um único grupo, as médias dos %FCmax correspondentes a 50, 60, 70, 80 e 90% %VO2max foram 67, 73, 80, 87, e 93%, respectivamente. CONCLUSÃO: Nos grupos analisados, a relação entre o %VO2max e %FCmax durante o exercício incremental no ciclismo não é dependente do estado e especificidade do treinamento aeróbio. Abstract in english OBJECTIVE: To determine the effects of the status and specificity of exercise training in the ratio between maximum oxygen consumption (%VO2max) and the percentage of maximal heart rate (%HRmax) during incremental exercise on a cycle ergometer. METHODS: Seven runners, 9 cyclists, 11 triathletes, and 12 sedentary individuals, all male and apparently healthy, underwent exhaustive incremental exercise on cycle ergometers. Linear regressions between %VO2max x %HRmax were dete (more) rmined for each individual. Based on these regressions, %HRmax was assessed corresponding to a determined %VO2max (50, 60, 70, 80, and 90%) from each participant. RESULTS: Significant differences were not found between the groups in %HRmax for each of the %VO2max assessed. Analyzing the volunteers as a single group, the average of the corresponding %HRmax to 50, 60, 70, 80, and 90% %VO2max were 67, 73, 80, 87, and 93%, respectively. CONCLUSION: The ratio between %VO2max and %HRmax in the groups assessed during incremental exercise on the bicycle is not dependent on the status and specificity of aerobic exercise training.

Caputo, Fabrizio; Greco, Camila Coelho; Denadai, Benedito Sérgio

2005-01-01

10

Selective solution-phase synthesis of BiOCl, BiVO4 and ?-Bi2O3 nanocrystals in the reaction system of BiCl3-NH4VO3-NaOH  

International Nuclear Information System (INIS)

[en] In this study, we demonstrate a straightforward solution-phase method for the selective synthesis of BiOCl, BiVO4 and ?-Bi2O3 nanocrystals by simply manipulating the reaction temperature and the BiCl3-to-NaOH mole ratio in the reaction system of BiCl3-NH4VO3-NaOH. The experimental results revealed that BiOCl, as the sole product, was prepared when designating the reaction temperature ranging from room temperature to 100 deg. C, regardless of the BiCl3-to-NaOH mole ratio; on the other hand, BiOCl, BiVO4, and ?-Bi2O3 nanocrystals could be selectively prepared at 140-180 deg. C, depending on the BiCl3-to-NaOH mole ratio in solution. Significantly, we first report on fabricating ?-Bi2O3 sample, the high-temperature cubic phase commonly stabilized at 730-824 deg. C, at the low reaction temperature of 140-180 deg. C under solution-phase synthetic conditions. In addition, the ?-Bi2O3 sample exhibits strong emission at room temperature. - Graphical abstract: In this study, we demonstrate a straightforward solution-phase method for the selective synthesis of BiOCl, BiVO4 and ?-Bi2O3 nanocrystals by simply manipulating the reaction temperature and the BiCl3-to-NaOH mole ratio in the reaction system of BiCl3-NH4VO3-NaOH

2008-01-01

11

Investigation of complexing in solutions of salt mixture In(NO3)3-NaVO3  

International Nuclear Information System (INIS)

[en] Spectrophotometry, conductometry and pH-metry are used to investigate properties and composition of the solid phases of isomolar series of In(NO3)3-NaVO3 salt mixture solutions and series of solutions having constant concentration of one of the components and varied of the other. Results of investigation are presented. It is stated that in the investigated solution series in weakly acid media HPA with the ratios [In3+]:[V5+] being equal to 11:1, 6:1, and 1:9, are formed. Composition of the complexes is mainly defined by the ratio of the components in In(NO3)3 and NaVO3 salt mixture solutions and the medium acidity. Compounds of Na2OxIn2O3x2.5V2O5x8.5H2O and Cs2OxIn2O3x6V2O5x6.5H2O empirical formulae are separated. Results of IR spectroscopy, derivatography and X-ray phase analysis of the corresponding salts are presented

1987-01-01

12

Selective solution-phase synthesis of BiOCl, BiVO4 and ?-Bi2O3 nanocrystals in the reaction system of BiCl3-NH4VO3-NaOH  

Science.gov (United States)

In this study, we demonstrate a straightforward solution-phase method for the selective synthesis of BiOCl, BiVO4 and ?-Bi2O3 nanocrystals by simply manipulating the reaction temperature and the BiCl3-to-NaOH mole ratio in the reaction system of BiCl3-NH4VO3-NaOH. The experimental results revealed that BiOCl, as the sole product, was prepared when designating the reaction temperature ranging from room temperature to 100 °C, regardless of the BiCl3-to-NaOH mole ratio; on the other hand, BiOCl, BiVO4, and ?-Bi2O3 nanocrystals could be selectively prepared at 140-180 °C, depending on the BiCl3-to-NaOH mole ratio in solution. Significantly, we first report on fabricating ?-Bi2O3 sample, the high-temperature cubic phase commonly stabilized at 730-824 °C, at the low reaction temperature of 140-180 °C under solution-phase synthetic conditions. In addition, the ?-Bi2O3 sample exhibits strong emission at room temperature.

Chen, Xiang Ying; Zhang, Zhong Jie; Lee, Soon W.

2008-01-01

13

Cinética do consumo de oxigênio e tempo limite na vvo2max: comparação entre homens e mulheres/ Oxygen uptake kinetics and threshold time at the vVO2max: tomparison between men and women  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Foi investigada a influência do gênero no tempo limite (Tlim) e na cinética do VO2 durante corrida na velocidade associada ao VO2max (vVO2max) em nove homens e nove mulheres, todos adultos, jovens e sedentários, com idades entre 20 e 30 anos. Homens e mulheres realizaram dois testes em esteira rolante, sendo um teste incremental para determinar VO2max (42,66 ± 4,50 vs. 32,92 ± 6,03mL.kg-1.min-1) e vVO2max (13.2 ± 1.5 vs. 10,3 ± 2,0km.h-1), respectivamente. Um segu (more) ndo teste com carga constante na vVO2max até a exaustão. O Tlim e a cinética do VO2 foram determinados. Não houve diferença significante entre homens e mulheres para constante de tempo (?) (35,76 ± 21,03 vs. 36,5 ± 6,21s, respectivamente; P = 0,29); Tlim (308 ± 84,3 vs. 282,11 ± 57,19s, respectivamente; P = 0,68), tempo para atingir o VO2max (TAVO2max) (164,48 ± 96,73 vs. 167,88 ± 28,59s, respectivamente; P = 0,29), tempo para atingir o VO2max em percentual do Tlim (%Tlim) (50,24 ± 16,93 vs. 62,63 ± 16,60%, respectivamente; P = 0,19), tempo mantido no VO2max (TMVO2max) (144,08 ± 42,55 vs. 114,23 ± 76,96s, respectivamente; P = 0,13). Estes resultados sugerem que a cinética do VO2 e o Tlim são similares entre homens e mulheres sedentários na vVO2max. Abstract in english The aim of this study was to investigate the influence of gender on Tthre and VO2 response during running exercise performed at vVO2max. Therefore, eighteen untrained individuals (9 male and 9 female) with normal weight and aged between 20 - 30 years (VO2max = 42.66 ± 4.50 vs 32.92 ± 6.03 mL.kg-1.min-1 and vVO2max = 13.2 ± 1.5 vs 10.3 ± 2.0 km.h-1, for male and female, respectively) were assessed. Subjects performed two exercise tests on treadmill. First one was an in (more) cremental test to determine VO2max, velocity at VO2max (vVO2max) and second test was performed at steady velocity - vVO2max - until exhaustion. The threshold time (Tthre) and VO2 kinetics response was determined. No significant differences were observed between men and women for time constant (?) (35.76 ± 21.03 vs 36.5 ± 6.21s, respectively; P = 0.29); Tthre (308 ± 84.3 vs 282.11 ± 57.19s, respectively; P = 0.68), time to achieve VO2max (TAVO2max) (164.48 ± 96.73 vs 167.88 ± 28.59s, respectively; P = 0.29), time to achieve VO2max in Tthre percentage (%Tthre) (50.24 ± 16.93 vs 62.63 ± 16.60%, respectively; P = 0.19); time maintained at VO2max (TMVO2max) (144.08 ± 42.55 vs 114.23 ± 76.96s, respectively; P = 0.13). These results suggest that the VO2 kinetics response and Tthre is similar between untrained men and women at the vVO2max.

Azevedo, Paulo Henrique Silva Marques de; Oliveira, João Carlos de; Simões, Herbert Gustavo; Baldissera, Vilmar; Perez, Sérgio Eduardo de Andrade

2010-08-01

14

Cinética do consumo de oxigênio e tempo limite na vvo2max: comparação entre homens e mulheres Oxygen uptake kinetics and threshold time at the vVO2max: tomparison between men and women  

Directory of Open Access Journals (Sweden)

Full Text Available Foi investigada a influência do gênero no tempo limite (Tlim) e na cinética do VO2 durante corrida na velocidade associada ao VO2max (vVO2max) em nove homens e nove mulheres, todos adultos, jovens e sedentários, com idades entre 20 e 30 anos. Homens e mulheres realizaram dois testes em esteira rolante, sendo um teste incremental para determinar VO2max (42,66 ± 4,50 vs. 32,92 ± 6,03mL.kg-1.min-1) e vVO2max (13.2 ± 1.5 vs. 10,3 ± 2,0km.h-1), respectivamente. Um segundo teste com carga constante na vVO2max até a exaustão. O Tlim e a cinética do VO2 foram determinados. Não houve diferença significante entre homens e mulheres para constante de tempo (?) (35,76 ± 21,03 vs. 36,5 ± 6,21s, respectivamente; P = 0,29); Tlim (308 ± 84,3 vs. 282,11 ± 57,19s, respectivamente; P = 0,68), tempo para atingir o VO2max (TAVO2max) (164,48 ± 96,73 vs. 167,88 ± 28,59s, respectivamente; P = 0,29), tempo para atingir o VO2max em percentual do Tlim (%Tlim) (50,24 ± 16,93 vs. 62,63 ± 16,60%, respectivamente; P = 0,19), tempo mantido no VO2max (TMVO2max) (144,08 ± 42,55 vs. 114,23 ± 76,96s, respectivamente; P = 0,13). Estes resultados sugerem que a cinética do VO2 e o Tlim são similares entre homens e mulheres sedentários na vVO2max.The aim of this study was to investigate the influence of gender on Tthre and VO2 response during running exercise performed at vVO2max. Therefore, eighteen untrained individuals (9 male and 9 female) with normal weight and aged between 20 - 30 years (VO2max = 42.66 ± 4.50 vs 32.92 ± 6.03 mL.kg-1.min-1 and vVO2max = 13.2 ± 1.5 vs 10.3 ± 2.0 km.h-1, for male and female, respectively) were assessed. Subjects performed two exercise tests on treadmill. First one was an incremental test to determine VO2max, velocity at VO2max (vVO2max) and second test was performed at steady velocity - vVO2max - until exhaustion. The threshold time (Tthre) and VO2 kinetics response was determined. No significant differences were observed between men and women for time constant (?) (35.76 ± 21.03 vs 36.5 ± 6.21s, respectively; P = 0.29); Tthre (308 ± 84.3 vs 282.11 ± 57.19s, respectively; P = 0.68), time to achieve VO2max (TAVO2max) (164.48 ± 96.73 vs 167.88 ± 28.59s, respectively; P = 0.29), time to achieve VO2max in Tthre percentage (%Tthre) (50.24 ± 16.93 vs 62.63 ± 16.60%, respectively; P = 0.19); time maintained at VO2max (TMVO2max) (144.08 ± 42.55 vs 114.23 ± 76.96s, respectively; P = 0.13). These results suggest that the VO2 kinetics response and Tthre is similar between untrained men and women at the vVO2max.

Paulo Henrique Silva Marques de Azevedo; João Carlos de Oliveira; Herbert Gustavo Simões; Vilmar Baldissera; Sérgio Eduardo de Andrade Perez

2010-01-01

15

Growth of YbVO4 crystals evolved from hot corrosion reactions of Yb2Zr2O7 against V2O5 and Na2SO4 + V2O5  

Science.gov (United States)

YbVO4 evolved from hot corrosion of V2O5-coated Yb2Zr2O7 is particle-shaped.YbVO4 exhibits rod-like crystal from hot corrosion of (Na2SO4 + V2O5)-coated Yb2Zr2O7.The mechanism is explained by a model based on dissolution–precipitation process.

Li, Sa; Liu, Zhan-Guo; Ouyang, Jia-Hu

2013-07-01

16

VO2 pico e inclinação VE/VCO2 na era dos betabloqueadores na insuficiência cardíaca: uma experiência brasileira Peak VO2 and VE/VCO2 slope in betablockers era in patients with heart failure: a brazilian experience  

Directory of Open Access Journals (Sweden)

Full Text Available FUNDAMENTO: Estudos têm demonstrado que o consumo de oxigênio de pico (VO2 pico) e a inclinação VE/VCO2 são preditores de sobrevida em pacientes com insuficiência cardíaca (IC). Entretanto, com a adição do betabloqueador no tratamento da IC, os valores de prognóstico do VO2 pico e da Inclinação VE/VCO2 não estão totalmente estabelecidos. OBJETIVO: Avaliar o efeito dos betabloqueadores no valor de prognóstico do VO2 pico e da inclinação VE/VCO2 em pacientes com IC. MÉTODOS: Estudamos 391 pacientes com insuficiência cardíaca, com idade de 49 ± 14 anos e fração de ejeção do ventrículo esquerdo de 38 ± 10%. Total de pacientes que usavam (grupo I - GI) e não usavam (grupo II - GII) betabloqueadores: 229 e 162, respectivamente. Todos os pacientes foram submetidos a teste de esforço cardiopulmonar, em esteira, usando o protocolo de Naughton. RESULTADOS: O VO2 pico 16 ml.kg-1.min-1 categorizaram pacientes com melhor prognóstico em médio prazo. A faixa do VO2 pico entre > 10 e BACKGROUND: Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully established. OBJECTIVE: To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF. METHODS: We studied 391 patients with heart failure, aged 49 ± 14 years and presenting a left ventricular ejection fraction of 38 ± 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol. RESULTS: A peak VO2 16 ml.kg-1.min-1 categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and < 16 ml.kg-1.min-1 indicated moderate risk for cardiac event in four years of follow up. The betablocker use significantly reduced the VE/VCO2 slope in patients with HF. The prognostic value of the VE/VCO2 slope < 34 in the group using betablocker can reflect the impact of the drug on this cardiorespiratory variable. CONCLUSION: A low peak VO2 and an elevated VE/VCO2 slope are strong and independent predictors of cardiac events in HF. Thus, both variables remain important survival predictors in patients with HF, especially at the age of betablockers.

Guilherme Veiga Guimarães; Mário Sérgio Vaz da Silva; Veridiana Moraes d'Avila; Silvia Moreira Ayub Ferreira; Christiano Pereira Silva; Edimar Alcides Bocchi

2008-01-01

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Calefaccion centralizada por biomasa, Cuéllar  

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Full Text Available A plant of municipal central heating feeded with residual biomass, has been created in Cuéllar (Segovia, Spain), in order to demostrate its technical viability and to make more confortable the life of village inhabitants. Those residual biomass used as combustible, comes from the pine seeds, the key industry in the area. The calorific energy generated by combustion of those pine seeds, serves to heat the water to be send later through different pipes crossing the village. So, heating services and sanitary hot water are used according to the moment of the year. The study of the operative plant, allow us to discern the more adecuated operation parameters. reaching a total thermical yield of 60%. So its technical and economical viability concerning other traditional combustibles, its big environmental contribution to the production of energy, in addition to the social advantages -1ike the creation of new working jobs and the development of alternative activities in agricultura1 and forest areas- have contributed to present this plant as a model to be extended to other areas with potential biomass.Con el fin de demostrar su viabilidad técnica y económica y dar servicio a los habitantes de la localidad, se ha instalado en Cuéllar (Segovia, España), una planta de calefacción municipal alimentada con biomasa residual. Como combustible utiliza los residuos biomásicos procedentes de la industria piñonera de la zona. La energía calorífica generada por el proceso de combustión de éstos, calienta agua que es distribuida a través de un circuito de tuberías aisladas a través de la ciudad. Se proporcionan así los servicios de calefacción y agua caliente sanitaria según la época del año. El estudio de la operación de la planta, ha permitido caracterizar los parámetros de funcionamiento más adecuados. habiéndose obtenido un rendimiento térmico total de la instalación del 60%. quedando justificada su viabilidad técnica y económica respecto a otros combustibles tradicionales. Su gran contribución medioambiental a la producción de energía. además de las ventajas sociales como la creación de puestos de trabajo y desarrollo de actividades alternativas en zonas agrícolas y forestales, hacen que esta instalación sirva de modelo para su desarrollo en otras poblaciones con potencial de biomasa.

Cantalejo Olmos, Octavio; Antolín Giraldo, Gregorio; Díez Castilla, Santiago; Verdú Pérez, Jesús

2001-01-01

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VO2 pico e inclinação VE/VCO2 na era dos betabloqueadores na insuficiência cardíaca: uma experiência brasileira/ Peak VO2 and VE/VCO2 slope in betablockers era in patients with heart failure: a brazilian experience  

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Full Text Available Abstract in portuguese FUNDAMENTO: Estudos têm demonstrado que o consumo de oxigênio de pico (VO2 pico) e a inclinação VE/VCO2 são preditores de sobrevida em pacientes com insuficiência cardíaca (IC). Entretanto, com a adição do betabloqueador no tratamento da IC, os valores de prognóstico do VO2 pico e da Inclinação VE/VCO2 não estão totalmente estabelecidos. OBJETIVO: Avaliar o efeito dos betabloqueadores no valor de prognóstico do VO2 pico e da inclinação VE/VCO2 em paciente (more) s com IC. MÉTODOS: Estudamos 391 pacientes com insuficiência cardíaca, com idade de 49 ± 14 anos e fração de ejeção do ventrículo esquerdo de 38 ± 10%. Total de pacientes que usavam (grupo I - GI) e não usavam (grupo II - GII) betabloqueadores: 229 e 162, respectivamente. Todos os pacientes foram submetidos a teste de esforço cardiopulmonar, em esteira, usando o protocolo de Naughton. RESULTADOS: O VO2 pico 16 ml.kg-1.min-1 categorizaram pacientes com melhor prognóstico em médio prazo. A faixa do VO2 pico entre > 10 e Abstract in english BACKGROUND: Studies have demonstrated that peak oxygen consumption (peak VO2) and the VE/VCO2 slope are predictors of survival in patients with heart failure (HF). However, with the advent of betablockers in the treatment of HF, the prognostic values of peak VO2 and VE/VCO2 slope have not been fully established. OBJECTIVE: To evaluate the effect of betablocker use on the prognostic value of peak VO2 and VE/VCO2 slope in patients with HF. METHODS: We studied 391 patients w (more) ith heart failure, aged 49 ± 14 years and presenting a left ventricular ejection fraction of 38 ± 10%. The total number of patients that used (Group I - GI) or did not use (Group II - GII) betablockers was 229 and 162, respectively. All patients were submitted to a cardiopulmonary stress test on a treadmill, using the Naughton protocol. RESULTS: A peak VO2 16 ml.kg-1.min-1 categorizes patients with a better mid-term prognosis. Peak VO2 values between > 10 and

Guimarães, Guilherme Veiga; Silva, Mário Sérgio Vaz da; d'Avila, Veridiana Moraes; Ferreira, Silvia Moreira Ayub; Silva, Christiano Pereira; Bocchi, Edimar Alcides

2008-07-01

19

DISTANCE LEARNING IN SLOVAKIA AND IN THE CHOSEN COUNTRIES OF EUROPEAN UNION / Dištan?né vzdelávanie na Slovensku a vo vybraných krajinách EÚ  

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Full Text Available Authors refer to the theme of distance learning and its application in Slovak republic and in the chosen countries of European Union. In the article there is a brief history of distance learning usage.Autori sa v príspevku venujú problematike využitia dištan?ného vzdelávania ako na Slovensku, tak aj vo vybraných krajinách Európskej únie. V príspevku uvádzajú stru?ný historický preh?ad používania dištan?ného vzdelávania a jednej z jeho foriem - e-learningu.

Lan?ari? Drahoš; Polá?iková Katarína

2008-01-01

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Resonant soft x-ray emission spectroscopy of V2O3, VO2 and NaV2O5  

International Nuclear Information System (INIS)

[en] Resonant soft X-ray emission (RSXE) spectra of V2O3, VO2 and NaV2O5 were recorded for a series of excitation energies at resonances of the V L- and O K-absorption band. The V L- and O K-emission in these vanadium oxide bands possess considerable overlap. By resonant excitation we can tune the energy to the absorption thresholds, thereby eliminating this overlap. Hereby we obtain the V 3d and O 2p projected density-of-states of the valence band. Resonant inelastic X-ray scattering (RIXS) is found to be weak in V2O3, which we explain as being due to its metallic character at room temperature. Vanadium dioxide (VO2), semiconducting at room temperature, shows considerable RIXS features only at the O K-emission band. Distinct RIXS structures are visible in the RSXE spectra of the insulator NaV2O5. In the emission spectra excited at the V L-thresholds of this ternary vanadium oxide, dexcitations of the V dxy subband at an energy loss of -1:7 eV are observed. Our observation, that RIXS is stronger for insulators than for metals, should be taken advantage of for studying insulator-to-metal transitions in vanadium compounds in the future

2004-01-01

 
 
 
 
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VoIP Security  

Digital Repository Infrastructure Vision for European Research (DRIVER)

VOIP or Voice Over Internet Protocol is a common term for phone service over IP based networks. There are much information about VoIP and some of how VoIP can be secured. There is however no standard for VoIP and no general solution for VoIP Security. The security in VoIP systems today are often non...

Fontanini, Piero

22

Predição da potência aeróbia (VO2máx) de crianças e adolescentes em teste incremental na esteira rolante/ Prediction of aerobic power (VO2max) of children and adolescents during an incremental treadmill test  

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Full Text Available Abstract in portuguese O consumo máximo de oxigênio (VO2máx) é a quantidade máxima de energia que pode ser produzida pelo metabolismo aeróbio em determinada unidade de tempo, podendo ser determinado direta ou indiretamente através de equações preditivas. O objetivo deste trabalho foi elaborar uma equação preditiva específica para determinar o VO2máx de meninos de 10 a 16 anos. Quarenta e dois meninos realizaram teste ergoespirométrico de corrida em esteira rolante com velocidade i (more) nicial de 9 km/h até exaustão voluntária. Através da regressão linear múltipla foi possível desenvolver a seguinte equação para a determinação indireta do VO2máx: VO2máx (ml/min) = -1574,06 + (141,38 x Vpico) + (48,34 * Massa corporal), com erro padrão de estimativa = 191,5 ml/min (4,10 ml/kg/min) e o coeficiente de determinação = 0,934. Sugerimos que esta é uma fórmula adequada para predizer o VO2máx para esta população. Abstract in english The maximal oxygen uptake (VO2max) is the maximal quantity of energy that can be produced by the aerobic metabolism in certain time unity. It can be determined direct or indirectly by predictive equations. The objective of this study was to make a specific predictive equation to determine the VO2max from boys aged 10-16 years-old. Forty-two boys underwent a treadmill running ergospirometric test, with the initial velocity set at 9 km/h, until voluntary exhaustion. By the (more) multiple linear regression was possible to develop the following equation for the indirect determination of the VO2max: VO2max (ml/min) = -1574.06 + (141.38 x Vpeak) + (48.34 * Body mass), with standard error of estimate = 191.5 ml/min (4.10 ml/kg/min) and coefficient of determination = 0.934. We suggest that this formula is appropriate to predict VO2max for this population.

Machado, Fabiana Andrade; Denadai, Benedito Sérgio

2013-03-01

23

Programación por metas Energía alternativa mediante biomasa.  

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Full Text Available En este trabajo se presenta un modelo multicriterio de localización de centrales de generación de energía eléctrica mediante biomasa. Los objetivos considerados son: (1) minimizar el coste total de la operación, (2) maximizar la producción de electricidad obtenida, (3) maximizar la distancia entre plantas, (4) maximizar la aceptación social y (5) establecer las plantas o ampliaciones en aquellos lugares donde exista una mayor predisposición por parte de las administraciones locales. Finalmente, se concluye con una aplicación práctica mediante programación por metas ponderadas para la región andaluza, considerando los residuos procedentes del olivar como fuente de energía.

Fernández Carazo, Ana; Guerrero Casas, Flor María

2003-01-01

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Electron Paramagnetic Resonance Studies of Cu2+ and VO2+ Spin Probes in RO-Li2O-Na2O-K2O-B2O3 (R = Zn, Mg, Sr and Ba) Glass Systems  

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Full Text Available Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+ were prepared by the melt quenching method. X-ray diffraction studies of the samples did not reveal crystalline phases. EPR measurements were made at X-band frequencies with 100 kHz field modulation, at 310 K. Optical spectra were recorded in the wavelength range 300 nm - 800 nm. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values in the case of Cu2+ indicated that the ground state of Cu2+ was orbital (2B1g) and the site symmetry around Cu2+ is tetragonally distorted octahedral. The variation of gll and All with the alkaline earth oxide (RO) composition was found to be non-linear which may be due to the change in the ligand field strength at the site of Cu2+ ions. From the spin-Hamiltonian parameters of VO2+, it was observed that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (?gll/?g) of V4+ ion sites exhibited non-linear variation with RO content, which indicated change in the ligand field at the site of V4+. A broad optical absorption band was observed in the glass containing Cu2+ ions corresponding to the 2B1g ? 2B2g transition. From the EPR and optical data the bond parameters were evaluated. In the case of VO2+ ions, the covalency rates were estimated.

Abdul Hameed; Gokarakonda Ramadevudu; Siddey Laksmisrinivasa Rao; Mohmmad Shareefuddin; Mudumba Narasimha Chary

2012-01-01

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SECONDARY GRAMMAR SCHOOL STUDENTS ATTITUDES TOWARD ICT USING IN THE BIOLOGY AS THE SCHOOL SUBJECT / Názory študentov gymnázií na využívanie IKT vo vyu?ovacom predmete biológia  

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Full Text Available The influence of information and communication technologies and computers on our daily lives has been steadily increasing. This fact is one of factors, which can influence the change of attitudes toward information and communication technologies. In our contribution we are focused on finding differences in results between age and gender according to ICT attitudes. A questionnaire with 33 Likert type items was used as a research tool. The sample size consists of 518 students from 9 secondary grammar schools. Students attented the all of grades. Data were evaluated with the factor analysis and Analysis of variance (ANOVA).Vplyv informa?ných a komunika?ných technológií a po?íta?ov na nᚠkaždodenný život je neustále narastajúci. Tento fakt je jedným z faktorov, ktoré môžu ovplyvni? zmenu postojov resp. názorov na informa?né a komunika?né technológie. V príspevku sa snažíme nájs? rozdiely vo výsledkoch v názore na používanie IKT medzi rôznymi vekovými skupinami študentov a medzi chlapcami a diev?atami. Ako výskumný nástroj bol použitý dotazník Likertovho typu s 33 položkami. Výskumu sa zú?astnilo 518 študentov z 9 gymnázií, pri?om boli zastúpené všetky ro?níky. Na odhalenie rozdielov vo výsledkoch bola použitá faktorová analýza a analýza rozptylu (ANOVA).

Kubiatko Milan

2009-01-01

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Potencial de producción de biomasa en una población natural de la ostra crassostrea rhizophorae, en la laguna grande de obispo, Golfo de Cariaco, Venezuela/ Biomass production potential in a natural population of the oyster crassostrea rhizophorae in laguna grande de obispo; Cariaco Gulf; Venezuela/ Potencial de produção de biomassa na população natural da ostra crassostrea rhizophorae, na lagoa grande de obispo, Golfo de Cariaco, Venezuela  

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Full Text Available Abstract in portuguese A ostra Crassostrea rhizophorae é um bivalves de interesse comercial, comum nas comunidades de manglares no oriente da Venezuela. Para avaliar o potencial de geração de biomassa da espécie se realizaram amostras mensais desde maio de 2002 até maio de 2003, em duas estações da população natural de Laguna Grande do Obispo, estado Sucre, Venezuela. Utilizando um desenho de amostras aleatório simples se determinou a abundância e a biomassa de bivalves fixados a ra? (more) ?zes de Rhizophora manglae, estimando a produção secundária pelo método da taxa específica de crescimento. Determinou-se uma densidade média de 818,13ind/m² de raiz com biomassa média em peso seco de 662,39g/m², sem diferenças significativas entre estações nem meses. Utilizando um modelo de crescimento com parâmetros finais de L¥= 87,68 e K= 0,19/mês, se obteve uma produção secundária total de 2.355,546g/m²/ano, sendo o intervalo de tamanho 50,01-60,00mm o que aportou a maior quantidade (382,353g/m²/ano). A máxima produção se obteve em jan-fev de 2003 (243,906g/m²/ano) e a mínima em mai-jun de 2002 (100,80g/m²/ano). A produção por indivíduo foi de 43,283g/m²/ano com a mesma tendência temporal da total. Ainda que não se determinasse correlação dos incrementos de produção com a temperatura e salinidade, a maior produção ocorreu durante a época de surgência costeira na zona. A relação produção/biomassa foi de 3,55/ano, resultados que indicam que C. rhizophorae apresenta um grande potencial para atividades de aqüicultura na zona por sua reprodução continua e altas taxas de crescimento e produtividade. Abstract in spanish La ostra Crassostrea rhizophorae es un bivalvo de interés comercial, común en las comunidades de manglar en el oriente de Venezuela. Para evaluar el potencial de generación de biomasa de la especie se realizaron muestreos mensuales desde mayo 2002 hasta mayo 2003, en dos estaciones de la población natural de Laguna Grande del Obispo, estado Sucre, Venezuela. Utilizando un diseño de muestreo al azar simple se determinó la abundancia y la biomasa de bivalvos fijados a (more) raíces de Rhizophora manglae, estimando la producción secundaria por el método de la tasa específica de crecimiento. Se determinó una densidad promedio de 818,13ind/m² de raíz con biomasa promedio en peso seco de 662,39g/m², sin diferencias significativas entre estaciones ni meses. Utilizando un modelo de crecimiento con parámetros finales de L¥= 87,68 y K= 0,19/mes, se obtuvo una producción secundaria total de 2355,546g/m²/año, siendo el intervalo de talla 50,01-60,00mm el que aportó la mayor cantidad (382,353g/m²/año). La máxima producción se obtuvo en ene-feb 2003 (243,906g/m²/año) y la mínima en may-jun 2002 (100,80g/m²/año). La producción por individuo fue de 43,283g/m²/año con la misma tendencia temporal de la total. Aunque no se determinó correlación de los incrementos de producción con la temperatura y salinidad, la mayor producción ocurre durante la época de surgencia costera en la zona. La relación producción/biomasa fue de 3,55/año, resultados que indican que C. rhizophorae presenta un gran potencial para actividades de acuicultura en la zona por su reproducción continua y altas tasas de crecimiento y productividad. Abstract in english The oyster Crassostrea rhizophorae is a bivalve of commercial interest, common in mangrove communities of eastern Venezuela. This study was conducted in order to evaluate the production of biomass of species in a natural population of Laguna Grande de Obispo, Cariaco Gulf, Venezuela. Monthly samplings were carried out between May 2002 and May 2003 in two stations. Using a simple random sampling design, the abundance and biomass of bivalves fixed on mangrove roots Rhizopho (more) ra manglae were determined, estimating the secondary production by the specific growth rate method. Mean density was 818.13ind/m² and mean biomass was 662.39g/m² of root, without significant differences between st

Prieto, Antulio; Montes, Andrés; Ruiz, Lilia J

2008-10-01

27

Resonant soft x-ray emission spectroscopy of V{sub 2}O{sub 3}, VO{sub 2} and NaV{sub 2}O{sub 5}  

Energy Technology Data Exchange (ETDEWEB)

Resonant soft X-ray emission (RSXE) spectra of V2O3, VO2 and NaV2O5 were recorded for a series of excitation energies at resonances of the V L- and O K-absorption band. The V L- and O K-emission in these vanadium oxide bands possess considerable overlap. By resonant excitation we can tune the energy to the absorption thresholds, thereby eliminating this overlap. Hereby we obtain the V 3d and O 2p projected density-of-states of the valence band. Resonant inelastic X-ray scattering (RIXS) is found to be weak in V2O3, which we explain as being due to its metallic character at room temperature. Vanadium dioxide (VO2), semiconducting at room temperature, shows considerable RIXS features only at the O K-emission band. Distinct RIXS structures are visible in the RSXE spectra of the insulator NaV2O5. In the emission spectra excited at the V L-thresholds of this ternary vanadium oxide, dexcitations of the V dxy subband at an energy loss of -1:7 eV are observed. Our observation, that RIXS is stronger for insulators than for metals, should be taken advantage of for studying insulator-to-metal transitions in vanadium compounds in the future.

Schmitt, T.; Duda, L.-C.; Augustsson, A.; Guo, J.-H.; Nordgren, J.; Downes, J.E.; McGuinness, C.; Smith, K.E.; Dhalenne, G.; Revcolevschi, A.; Klemm, M.; Horn, S.

2004-03-03

28

Benefícios do Uso do VoIP: um estudo de caso na GMBenefits from the VOIP Use: a case study at GMBeneficios del Uso del VoIP: un estudio de caso en la GM  

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Full Text Available RESUMOEste artigo traz uma visão do que é o VoIP, assim como suas principais aplicações, os fatores que as empresas buscam para minimizar custos em telefonia, as vantagens e desvantagens, a agregação de novas tecnologias, como WI-FI e o VOIP, e o futuro da telefonia no Brasil.Serão analisadas as diferenças entre Telefonia IP e VOIP paralelamente, e será tratada como base e estudo de caso a empresa General Motors do Brasil. O objetivo é mostrar o conteúdo que envolve essa inovadora tecnologia. Podemos dizer que a vontade de abordar esse tema foi despertada não somente por ser uma tecnologia inovadora que vem substituindo a telefonia convencional reduzindo os custos das empresas e trocando serviços e equipamentos obsoletos por uma série de novos serviços e oferecendo muitos recursos e benefícios, mas nos chamou a atenção também pelo fato de ser uma tecnologia que está revolucionando o mercado de telecomunicações, já que as empresas de telefonia prestadoras de serviços consomem uma boa parte da renda das empresas e pessoas, e também por exigir, nesse período de transição, muita habilidade em adequar as necessidades do cliente ao uso dessas ferramentas.ABSTRACTThis article brings a vision about Voip, as well as itself main applications, the factors with that the companies search to decrease costs in telephony, the advantages and disadvantages, aggregation of new technologies as wi-fi to the VOIP and the future of the telephony in Brazil. The differences between Telephony IP and VOIP will be analyzed parallel, and will be showed with as base study case of the General Motors. Our objective for this subject is to show the content that involves this fantastic technology. We can say that will to approach this subject it was influenced not only by being an innovative technology that comes substituting the conventional telephony, reducing the costs of the companies, and changing to services and obsolete equipments for a series of new services offering many resources and benefits, but it also called-us the attention for the fact being a technology whom making a revolution in telecommunications market where the rendering companies of telephony of services consumes a good part of the income of the companies and people, and also for This article brings a vision about VOIP, as well as its main applications, the factors with that the companies search to decrease costs in telephony, the advantages and disadvantages, aggregation of new technologies as wi-fi to the VOIP and the future of the telephony in Brazil. The differences between Telephony IP and VOIP will be analyzed in parallel, and will be showed having as base a case study of the General Motors. Our objective for this subject is to show the content that involves this fantastic technology. We can say that the will to approach this subject was influenced not only by being an innovative technology that comes to substitute the conventional telephony, reducing the costs of the companies, and changing services and obsolete equipment for a series of new services offering many resources and benefits, but it also called us the attention for the fact that this is a technology making a revolution in telecommunications market where the rendering companies of telephone services consumes a good part of the income of the companies and people, and also for demanding in this period of transition a great deal of ability to adequate the necessities of the customer to use of these tools and resources.RESUMENEste artículo aporta una visión de lo que es el VoIP, sus principales aplicaciones, los factores que las empresas buscan para minimizar costos en telefonía, las ventajas y desventajas, el agregado de nuevas tecnologías, como WI-FI y el VOIP y el futuro de la telefonía en Brasil.Se analizarán las diferencias entre Telefonía IP y VOIP y se tratará como base y estudio de caso la empresa General Motors de Brasil. La finalidad es mostrar el contenido que comprende esta innovadora tecnología. Podemos decir que el interés en este tema surgió prim

CRISTOFOLI, Fulvio; LAGO JUNIOR, Antonio Carlos; FEITERA, Carlos Henrique

2006-01-01

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Importancia energética y ambiental de la Biomasa en Colombia  

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Full Text Available Entiéndase por energía de la biomasa aquélla que se origina al procesar parcial o totalmente cualquier sustancia o materia originada a través del proceso de fotosíntesis de los vegetales. Luego comprende especies y microespecies que cumplen para el hombre y el ecosistema una función especial ligada a factores climáticos, geomorfológicos y socioeconómicos. Antes de la aparición de los combustibles fósiles (otra forma concentrada de biomasa) y de la electricidad, la biomasa constituía la principal oferta energética para el desarrollo y sobrevivencia del hombre. Si se tiene en cuenta que en el proceso de alimentación humana, el hombre y los animales utilizan menos del10% de la biomasa producida, queda un sobrante en estado sólido o en suspensión y que, por sus grandes volúmenes, genera problemas de contaminación en el campo y la ciudad, por ejemplo, basuras, residuos de plazas de mercado, pulpa de café, residuos de matadero, de procesamiento de vegetales, lácteos, y licoreras, residuos domésticos y residuos animales entre otros. Para el procesamiento o aprovechamiento de estos residuos existen tecnologías que buscan incorporarlos, en términos de materia y/o energía, a los procesos energéticos y agrícolas, captando de ellos, principalmente los valiosos elementos que los originaron. Dentro de estas tecnologías vale resaltar aquéllas basadas en los procesos microbiológicos, como las fermentaciones aeróbica y anaeróbica con un impacto ambiental nulo o positivo, reduciendo a nivel urbano los efectos de la contaminación y aportando fertilizantes y energía en el sector rural para la producción agrícola y bienestar social. Un efecto de su implantación sería la reducción de la contaminación de las aguas por material orgánico y sedimentos y la disminución en el consumo de, por lo menos unos diez millones de toneladas de leña al año que son utilizados por nuestros campesinos en sus actividades domésticas y de producción.

Hernández Luis Alfredo

1994-01-01

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Cuantificación de ácidos grasos a partir de biomasa microalgal  

Directory of Open Access Journals (Sweden)

Full Text Available Long chain polyunsaturated fatty acids are focusing the interest of researchers as long as analytical techniques are being improved. The Lepage and Roy direct transesterification method is being widely used to measure fatty acid content of microalgae which are proposed as potential sources of these products. In this paper, the physical state of the biomass to be analyzed is studied. Comparison has been stated between lyophilized biomass and wet biomass just harvested. Furthermore, the amount of sample and the number of methyl ester extractions have also been studied. From the statistical analysis carried out, wet biomass to fatty acid determination and the adequate range of sample are proposed. Three methyl ester extractions improve the resolution of GC analysis.El interés creciente por los ácidos grasos poliinsaturados de cadena larga viene favorecido por la mejora de las técnicas de análisis. La metodología de transesterificación directa propuesta por Lepage y Roy está siendo ampliamente utilizada para la determinación del contenido en ácidos grasos de microalgas, consideradas como potenciales fuentes de estos productos. En el presente trabajo, se analiza la influencia del estado físico de la biomasa analizada, seca, normalmente por liofilización, o húmeda recién cosechada del cultivo. Asimismo, se analiza el efecto de la cantidad de biomasa empleada y del número de extracciones de los esteres metílicos obtenidos. Del estudio estadístico realizado se pone de manifiesto la importancia del estado físico de la muestra, aconsejándose el uso de biomasa directamente obtenida del cultivo. Se proponen los intervalos de cantidad de biomasa para metilación, así como la conveniencia de realizar tres extracciones previas a la inyección en el cromatógrafo, que favorece la resolución del análisis.

García Sánchez, J. L.; Molina Grima, E.; García Camacho, F.; Sánchez Pérez, J. A.; Giménez Giménez, A.

1993-01-01

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La biomasa en la producción de electricidad en España  

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Full Text Available The generation of electricity using biomass began in Spain in the mid-1990s. In this paper, we examine the combustible products used in the generation of this type of electricity, the legal framework protecting its production, the evolution of the installed power and its territorial distribution, the environmental impact of biomass as a renewable energy, the energy policy supporting this technology and the problems for the development of biomass as a energy source in Spain.[es] La producción de electricidad con biomasa comienza su desarrollo en España a mediados de los años noventa. En este artículo se analizan los productos combustibles de biomasa destinados a la generación de electricidad, el marco legal que protege esta producción, la evolución de la potencia instalada y su distribución territorial, el impacto ambiental de la biomasa como energía renovable, la política energética de apoyo a esta tecnología, y los problemas para el desarrollo de la biomasa como fuente energética en España. [fr] La biomasse dans la production d´électricité en Espagne. La production d'électricité avec biomasse commence son développement en Espagne vers le milieu des années quatre-vingt-dix. Dans cet article nous analysons les produits combustibles de biomasse destines à engendrer de l'électricité, le cadre légal qui protégé cette production, l'évolution de la puissance installée, la répercussion de l'environnement de la biomasse comme énergie renouvelable, la politique énergétique de soutien à cette technologie et les problèmes pour le développement de la biomasse comme source énergétique en Espagne.

Espejo Marín, Cayetano

2005-01-01

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Determinanty zamestnanosti vo verejnom sektore pobaltských štátov  

Directory of Open Access Journals (Sweden)

Full Text Available V príspevku sa pozornos? sústre?uje na vývojzamestnanosti vo verejnom sektore pobaltských štátov, Estónska,Litvy a Lotyšska, za obdobie od 2000Q1 až 2010Q4 v porovnanís vývojom zamestnanosti v súkromnom sektore. Cie?om príspevkuje identifikova? vnútorné kauzálne súvislosti tohto vývoja a stanovi?jeho k?ú?ové faktory. Za týmto ú?elom je konštruovaný systémlineárnych simultánnych rovníc, pomocou ktorého sú stanovenék?ú?ové faktory vývoja zamestnanosti vo verejnom sektore v trochpobaltských štátoch a zárove? sú zistené empirické paradoxy tohtovývoja. Ukazuje sa, že v každom štáte pôsobia iné faktory ur?ujúcevývoj zamestnanosti vo verejnom sektore, ?o popiera existenciujednotného a univerzálneho výkladu teórie zamestnanosti voverejnom sektore.

Peter Bilka; Martin Bo?a

2012-01-01

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POTENCIALIDADES DE GENERACIÓN DE ELETRICIDAD A PARTIR DE BIOMASA  

Directory of Open Access Journals (Sweden)

Full Text Available La instalación de una destilería de etanol para la Generación de Energía Renovable Integrada a la Producción de Alimentos (GERIPA) presenta muchas ventajas en comparación con las destilerías tradicionales. La biomasa constituye una de las principales fuentes de generación de energía limpia y barata, pasando de ser un subproducto a ser una salida fundamental del proceso productivo. En el trabajo se calcula la energía disponible en el bagazo y paja de caña y de sorgo, así como en el biogás obtenido, para producir vapor destinado a los procesos y a la producción de electricidad, utilizando un generador de vapor tradicional con eficiencia de 88%, y un turbogenerador de condensación y extracción con rendimiento de 70%. En particular, para el caso de una planta de este tipo productora de 125 000 L/día de etanol, la generación de electricidad a partir de la biomasa que esta industria produce, alcanza el valor 6,0 MW de potencia eléctrica a entregar al Sistema Energético Nacional. Constituye una fuente de desarrollo económico, social y estratégico, atendiendo al concepto de auto sostenibilidad dado en el Protocolo de Kyoto.

PEDRO A. RODRIGUEZ; GERALDO LOMBARDI; ALDO OMETTO; LOURDES M. ZUMALACARREGUI; OSNEY PEREZ

2010-01-01

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Estimación de biomasa por métodos alométricos, nutrimentos y carbono en plantaciones de palmito en Costa Rica  

Directory of Open Access Journals (Sweden)

Full Text Available El agroecosistema de palmito (Bactris gasipaes) es un sistema de producción sostenible en los trópicos húmedos. Los métodos alométricos permiten predecir la producción de biomasa en forma no destructiva en cualquier momento y a partir de este dato determinar las fases de crecimiento del cultivo, los componentes de la biomasa y los nutrimentos asociados a cada componente, así como el rendimiento económico esperado de una plantación. Los objetivos generales del presente trabajo fueron obtener y validar funciones de predicción de la biomasa seca y de palmitos producidos en plantaciones comerciales, para correlacionarlos con la biomasa y la producción comercial de palmitos en las mismas. De esta manera, en varias fincas de la región Atlántica de Costa Rica se cosechó plantas de palmito y se separó sus componentes: follaje, pecíolos y tallos. Se utilizó modelos de regresión no lineales para calcular en forma independiente los coeficientes de las ecuaciones y así estimar los componentes de la biomasa y de la biomasa total. El diámetro basal fue una variable más efectiva para predecir la producción de biomasa que la altura hasta la hoja candela, la altura total y el número de

Adrián Ares; Jimmy Boniche; José Pablo Quesada; Russell Yost; Eloy Molina; Thomas J. Smyth

2002-01-01

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Inhibition protein tyrosine phosphatases by an oxovanadium glutamate complex, Na2[VO(Glu)2(CH3OH)](Glu = glutamate).  

Science.gov (United States)

The insulin-sensitizing effect of vanadium complexes has been linked to their ability to inhibit protein tyrosine phosphatases (PTPs). Considering that vanadium complexes may exchange in vivo with amino acids, forming in situ vanadium-amino acid complexes, we have synthesized and characterized an oxovanadium glutamate complex, Na(2)[V(IV)O(Glu)(2)(CH(3)OH)]H(2)O (1·H(2)O). The complex showed potent inhibition against four human PTPs (PTP1B, TCPTP, HePTP, and SHP-1) with IC(50) in the 0.21-0.37 ?M ranges. Fluorescence titration studies suggest that the complex binds to PTP1B with the formation of a 2:1 complex. Enzyme kinetics analysis using Lineweaver-Burk plots indicates a typical competitive inhibition mode. PMID:20617368

Lu, Liping; Wang, Sulian; Zhu, Miaoli; Liu, Zhiwei; Guo, Maolin; Xing, Shu; Fu, Xueqi

2010-07-09

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Inhibition protein tyrosine phosphatases by an oxovanadium glutamate complex, Na2[VO(Glu)2(CH3OH)](Glu = glutamate).  

UK PubMed Central (United Kingdom)

The insulin-sensitizing effect of vanadium complexes has been linked to their ability to inhibit protein tyrosine phosphatases (PTPs). Considering that vanadium complexes may exchange in vivo with amino acids, forming in situ vanadium-amino acid complexes, we have synthesized and characterized an oxovanadium glutamate complex, Na(2)[V(IV)O(Glu)(2)(CH(3)OH)]H(2)O (1·H(2)O). The complex showed potent inhibition against four human PTPs (PTP1B, TCPTP, HePTP, and SHP-1) with IC(50) in the 0.21-0.37 ?M ranges. Fluorescence titration studies suggest that the complex binds to PTP1B with the formation of a 2:1 complex. Enzyme kinetics analysis using Lineweaver-Burk plots indicates a typical competitive inhibition mode.

Lu L; Wang S; Zhu M; Liu Z; Guo M; Xing S; Fu X

2010-12-01

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Electron Paramagnetic Resonance Studies of Cu2+ and VO2+ Spin Probes in RO-Li2O-Na2O-K2O-B2O3 (R = Zn, Mg, Sr and Ba) Glass Systems  

Directory of Open Access Journals (Sweden)

Full Text Available Mixed alkali and alkaline earth oxide glasses of RO-Li2O-Na2O-K2O-B2O3(R = Zn, Mg, Sr and Ba) system were studied by electron paramagnetic resonance (EPR) and optical absorption spectroscopy. Cu2+ and VO2+ ions were used as the spin probes. The glasses containing 1 mole% of Cu2+ and 2mole% of VO2+ were prepared by the melt quenching method. X-ray diffraction studies of the samples did not reveal crystalline phases. EPR measurements were made at X-band frequencies with 100 kHz field modulation, at 310 K. Optical spectra were recorded in the wavelength range 300 nm - 800 nm. From the EPR spectra the spin-Hamiltonian parameters were evaluated. The spin-Hamiltonian parameter values in the case of Cu2+ indicated that the ground state of Cu2+ was orbital (2B1g) and the site symmetry around Cu2+ is tetragonally distorted octahedral. The variation of gll and All with the alkaline earth oxide (RO) composition was found to be non-linear which may be due to the change in the ligand field strength at the site of Cu2+ ions. From the spin-Hamiltonian parameters of VO2+, it was observed that the vanadyl ions exist as VO2+ ions in octahedral coordination with tetragonal compression and have C4V symmetry with ground state dxy. Tetragonality (?gll/?g) of V4+ ion sites exhibited non-linear variation with RO content, which indicated change in the ligand field at the site of V4+. A broad optical absorption band was observed in the glass containing Cu2+ ions corresponding to the 2B1g ? 2B2g transition. From the EPR and optical data the bond parameters were evaluated. In the case of VO2+ ions, the covalency rates were estimated.

Abdul Hameed; Gokarakonda Ramadevudu; Siddey Laksmisrinivasa Rao; Mohmmad Shareefuddin; Mudumba Narasimha Chary

2012-01-01

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Biomasa acumulada e indicadores de calidad nutritiva en cebadilla chaqueña (Bromus auleticus Trinius ex Nees)  

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Full Text Available Bromus auleticus (cebadilla chaqueña) es considerada uno de los recursos forrajeros más promisorios delCono Sur. Presenta variación entre poblaciones que ha sido determinada para diversos caracteres vegetativos, lo cual podría traducirse en diferencias de producción y calidad de forraje. El objetivo del presente estudio fue evaluar dos procedencias de cebadilla chaqueña (Argentina y Uruguay) para biomasa acumulada e indicadores de calidad nutritiva en dos períodos del año (verano-otoño y otoño-primavera). Se compararon cinco clones uruguayos (U) y cinco argentinos (A), dispuestos al azar en surcos distanciados a 1 m entre sí, con 10 plantas cada uno. Se determinó biomasa acumulada por planta (B) y calidad, midiendo Fibra Detergente Neutra (FDN), Proteína Bruta (PB) y Digestibilidad de la Materia Seca (DMS) en dos momentos del año. En general, la biomasa fue de baja calidad debido al momento en que se realizaron los cortes, lo que limita elalcance de los resultados. Sin embargo, las diferencias observadas entre los clones en este estado de desarrollo podrían indicar la existencia de variación entre genotipos de cebadilla chaqueña U y A en biomasa y calidad nutritiva. En biomasa acumulada no se observó efecto significativo de origen. En todas las variablesde calidad evaluadas en verano-otoño, se encontraron diferencias significativas entre orígenes. En otoñoprimavera, las diferencias entre orígenes fueron significativas para DMS. Los clones U presentaron mayor PB, menor FDN y mayor DMS. Dentro de cada origen, los argentinos presentaron menos diferencias que los uruguayos, tanto en biomasa acumulada como en calidad. Para ninguno de los clones A o U se encontró coincidencia entre mayor biomasa y mayor calidad.

BUSTAMANTE, E.G.R.; RUIZ, M.A.1,2; MORICI, E.; BABINEC, F.J.2,3; PORDOMINGO, A.B.1

2012-01-01

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Synthesis, characterization and catalytic activity of two novel cis-dioxovanadium(v) complexes: [VO2(L)] and [VO2(Hlox)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Dois novos complexos [VO2(L)] e [VO2(HLox)] foram sintetizados e caracterizados por espectroscopias no IV, UV-Vis e RMN, voltametria cíclica, análise elementar e difração de raios X. A síntese do ligante inédito H2Lox também é descrita. Os complexos 1 e 2 foram obtidos pela reação de [VO(acac)2] com os respectivos ligantes HL e H2Lox. Alternativamente, 2 foi preparado a partir da reação de HL com [VO(acac)2] na presença de hidroxilamina, e através da reaçã (more) o de 1 com hidroxilamina. Dados cristalográficos mostram que 1 e 2 apresentam estruturas moleculares similares, onde o centro de vanádio(V) cis-dioxo encontra-se coordenado em um ambiente octaédrico distorcido formado pelos ligantes L- e HLox-, respectivamente. A atividade catalítica destes compostos foi avaliada na oxidação do cicloexano, utilizando H2O2 e t-BuOOH como oxidantes. Ambos apresentam seletividade > 70% para formação de cicloexilidroperóxido. Cálculos B3LYP/6-31G(d) foram empregados na otimização da geometria e para auxiliar na atribuição do espectro eletrônico. Abstract in english Two novel complexes, [VO2(L)] (1) and [VO2(HLox)] (2), were synthesized and characterized by IV, UV-Vis and NMR spectroscopy, cyclic voltammetry, elemental analysis and X-ray diffraction. The synthesis of a new ligand, H2Lox, is also described. Complexes 1 and 2 were obtained by the reaction of [VO(acac)2] with the ligands HL and H2Lox, respectively. Alternatively, 2 was also obtained by the reaction of HL with [VO(acac)2] in the presence of hydroxylamine, and by the reac (more) tion of 1 with hydroxylamine. Crystallographic data show that complexes 1 and 2 have similar molecular structures, in which the cis-dioxovanadium(V) center is coordinated to L- or HLox-, respectively, in a distorted octahedral environment. The catalytic activity of these compounds towards cyclohexane oxidation was evaluated using H2O2 and t-BuOOH as oxidants. Both complexes presented > 70% selectivity for cyclohexylhydroperoxide formation. B3LYP/6-31G(d) calculations were used to confirm the geometry and to help assign the electronic spectra.

Silva, Natália M. L.; Pinheiro, Carlos B.; Chacon, Eluzir P.; Resende, Jackson A. L. C.; Carneiro, José Walkimar de M.; Fernández, Tatiana L.; Scarpellini, Marciela; Lanznaster, Mauricio

2011-01-01

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VO? requirements of boxing exercises.  

UK PubMed Central (United Kingdom)

The purpose of this study was to quantify the physiological requirements of various boxing exercises such as sparring, pad work, and punching bag. Because it was not possible to measure the oxygen uptake (VO?) of "true" sparring with a collecting gas valve in the face, we developed and validated a method to measure VO? of "true" sparring based on "postexercise" measurements. Nine experienced male amateur boxers (Mean ± SD: age = 22.0 ± 3.5 years, height = 176.0 ± 8.0 cm, weight = 71.4 ± 10.9 kg, number of fights = 13.0 ± 9.5) of regional and provincial level volunteered to participate in 3 testing sessions: (a) maximal treadmill test in the LAB, (b) standardized boxing training in the GYM, and (c) standardized boxing exercises in the LAB. Measures of VO?, heart rate (HR), blood lactate concentration [LA], rated perceived exertion level, and punching frequencies were collected. VO? values of 43.4 ± 5.9, 41.1 ± 5.1, 24.7 ± 6.1, 30.4 ± 5.8, and 38.3 ± 6.5 ml·kg?¹·min?¹ were obtained, which represent 69.7 ± 8.0, 66.1 ± 8.0, 39.8 ± 10.4, 48.8 ± 8.5, and 61.7 ± 10.3%VO?peak for sparring, pad work, and punching bag at 60, 120, and 180 b·min?¹, respectively. Except for lower VO? values for punching the bag at 60 and 120 b·min?¹ (p < 0.05), there was no VO? difference between exercises. Similar pattern was obtained for %HRmax with respective values of 85.5 ± 5.9, 83.6 ± 6.3, 67.5 ± 3.5, 74.8 ± 5.9, and 83.0 ± 6.0. Finally, sparring %HRmax and [LA] were slightly higher in the GYM (91.7 ± 4.3 and 9.4 ± 2.2 mmol·L?¹) vs. LAB (85.5 ± 5.9 and 6.1 ± 2.3 mmol·L?¹). Thus, in this study simulated LAB sparring and pad work required similar VO? (43-41 ml·kg?¹·min?¹, respectively), which corresponds to ~70%VO?peak. These results underline the importance of a minimum of aerobic fitness for boxers and draw some guidelines for the intensity of training.

Arseneau E; Mekary S; Léger LA

2011-02-01

 
 
 
 
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VO? requirements of boxing exercises.  

Science.gov (United States)

The purpose of this study was to quantify the physiological requirements of various boxing exercises such as sparring, pad work, and punching bag. Because it was not possible to measure the oxygen uptake (VO?) of "true" sparring with a collecting gas valve in the face, we developed and validated a method to measure VO? of "true" sparring based on "postexercise" measurements. Nine experienced male amateur boxers (Mean ± SD: age = 22.0 ± 3.5 years, height = 176.0 ± 8.0 cm, weight = 71.4 ± 10.9 kg, number of fights = 13.0 ± 9.5) of regional and provincial level volunteered to participate in 3 testing sessions: (a) maximal treadmill test in the LAB, (b) standardized boxing training in the GYM, and (c) standardized boxing exercises in the LAB. Measures of VO?, heart rate (HR), blood lactate concentration [LA], rated perceived exertion level, and punching frequencies were collected. VO? values of 43.4 ± 5.9, 41.1 ± 5.1, 24.7 ± 6.1, 30.4 ± 5.8, and 38.3 ± 6.5 ml·kg?¹·min?¹ were obtained, which represent 69.7 ± 8.0, 66.1 ± 8.0, 39.8 ± 10.4, 48.8 ± 8.5, and 61.7 ± 10.3%VO?peak for sparring, pad work, and punching bag at 60, 120, and 180 b·min?¹, respectively. Except for lower VO? values for punching the bag at 60 and 120 b·min?¹ (p < 0.05), there was no VO? difference between exercises. Similar pattern was obtained for %HRmax with respective values of 85.5 ± 5.9, 83.6 ± 6.3, 67.5 ± 3.5, 74.8 ± 5.9, and 83.0 ± 6.0. Finally, sparring %HRmax and [LA] were slightly higher in the GYM (91.7 ± 4.3 and 9.4 ± 2.2 mmol·L?¹) vs. LAB (85.5 ± 5.9 and 6.1 ± 2.3 mmol·L?¹). Thus, in this study simulated LAB sparring and pad work required similar VO? (43-41 ml·kg?¹·min?¹, respectively), which corresponds to ~70%VO?peak. These results underline the importance of a minimum of aerobic fitness for boxers and draw some guidelines for the intensity of training. PMID:21217532

Arseneau, Eric; Mekary, Saïd; Léger, Luc A

2011-02-01

42

Switching to VoIP  

CERN Document Server

More and more businesses today have their receive phone service through Internet instead of local phone company lines. Many businesses are also using their internal local and wide-area network infrastructure to replace legacy enterprise telephone networks. This migration to a single network carrying voice and data is called convergence, and it's revolutionizing the world of telecommunications by slashing costs and empowering users. The technology of families driving this convergence is called VoIP, or Voice over IP. VoIP has advanced Internet-based telephony to a viable solution, piquing the

Wallingford, Theodore

2007-01-01

43

Heat capacities of FeVO4, CrVO4, and AlVO4 at low temperatures  

Energy Technology Data Exchange (ETDEWEB)

The authors experimentally determine the heat capacities of FeVO4, CrVO4, and AlVO4 at 3-80 degrees K. They use a vacuum adiabatic calorimeter with periodic heat feed, germanium resistance thermometer, and specimens prepared from special purity oxides by solid-phase synthesis in air. They present their data in four charts and a table.

Cheshnitskii, S.M.; Fotiev, A.A.; Kozhevnikov, V.L.; Surat, L.L.

1985-07-01

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Selective formation of VO2(A) or VO2(R) polymorph by controlling the hydrothermal pressure  

International Nuclear Information System (INIS)

Missing VO2(A) usually occurs during the preparation of VO2 polymorphs. This leads to an ambiguous understanding of the transformation between VO2 polymorphs. The calculation of the ground state energies for different VO2 polymorphs indicated that there is only a small energy gap between VO2(A) and VO2(R), which destined that the transformation from VO2(A) to VO2(R) should be pressure sensitive. This hypothesis was verified during the synthesizing of VO2 polymorphs by reducing V2O5 with oxalic acid through hydrothermal treatment process. Selective formation of pure phase VO2(A) or VO2(R) was achieved by controlling the hydrothermal pressure through varying the filling ratio at 270 deg. C. It was found that a filling ratio over 0.5 favors the formation of pure VO2(R) while a reduced filling ratio to 0.4 or lower results in the formation of VO2(A). Based on our experiments, VO2(B) nanobelts were always first formed and then it transformed to VO2(A) by assembling process at increased temperature or extended reaction time. Under further higher pressure, the VO2(A) transformed spontaneously to VO2(R) initialized from the volume shrinkage due to the formation of denser VO2(R). - Graphical abstract: Selective formation of VO2(A) or VO2(R) could be achieved by controlling the system pressure through varying the filling ratio during hydrothermal treatment. Highlights: ? Selective formation of VO2 polymorphs by controlling hydrothermal pressure. ? Ground state energy characteristics were revealed for the first time. ? Phase transformation mechanism was clearly elucidated.

2011-01-01

45

VO2máx estimado e sua velocidade correspondente predizem o desempenho de corredores amadores/ Estimated VO2max and its corresponding velocity predict performance of amateur runners  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Observa-se, nos últimos anos, um importante crescimento do número de praticantes de corrida com proporcional aumento da adesão destes às provas de rua. Nesta população, a identificação dos determinantes do desempenho parece ser necessária para otimização do tempo dedicado ao treinamento. O objetivo do estudo foi estabelecer a associação do consumo máximo de oxigênio (VO2máx) estimado, da velocidade crítica (VC) e da velocidade do VO2máx (V VO2máx), com (more) os desempenhos nas provas de 3,6 km em subida e 10 e 21,1 km no plano. Doze corredores amadores (9 homens) com 36 ± 5 anos de idade foram submetidos a quatro testes: 1 e 5 km de corrida, no plano; 3,6 km de corrida, com inclinação (?8%); e um teste para determinação indireta do VO2máx. A VC foi determinada através da relação linear entre a distância e o tempo de corrida dos dois primeiros testes. Os sujeitos participaram de duas provas oficiais de 10 km e 21,1 km. A V VO2máx foi estimada a partir do VO2máx, através de equações metabólicas. O VO2máx apresentou a melhor associação com o desempenho da corrida em 10 e 21,1 km no plano. Já na subida, a V VO2máx apresentou melhor associação. Considerando todas as provas, a variável com maior média associativa foi o VO2máx (0,91±0,07), seguido do V VO2máx (0,90±0,04) e VC (0,87±0,06), respectivamente. Este estudo demonstrou elevadas associações entre variáveis fisiológicas estabelecidas por métodos indiretos, de baixo investimento e alta praticidade, com o desempenho da corrida em 10 e 21,1 km, no plano, e 3,6 km, em subida. Abstract in english In recent years, there has been a substantial increase in the number of runners, with a proportional increase in their involvement in amateur street competition. Identification of the determinants of performance in this population appears necessary for optimization of time devoted to training. The objective of this study was to ascertain the association between estimated maximal oxygen uptake (VO2max), critical velocity (CV) and VO2max velocity (V VO2max) and athletic per (more) formance in the 3.6 km (uphill) and 10 and 21.1 km (flatland) events. Twelve amateur runners (nine male), mean age 36 ± 5 years underwent five tests: 1 and 5 km race on level ground, 3.6 km race with slope (?8%), and indirect VO2max measurement. CV was determined from the linear relationship between distance and run time on the first two tests. The subjects then took part in two official 10 km and 21.1 km (half marathon) races. V VO2max was calculated from the VO2max through a metabolic equation. VO2max showed the best association with running performance in the 10 and 21.1 km events. For the uphill race, V VO2max showed a better association. Overall, the variable with the highest average association was VO2max (0.91±0.07), followed by V VO2max (0.90±0.04) and VC (0.87±0.06). This study showed strong associations between physiological variables established by low-cost, user-friendly indirect methods and running performance in the 10 and 21.1 km (flatland) and 3.6 km (uphill) running events.

Santos, Tony Meireles; Rodrigues, Allan Inoue; Greco, Camila Coelho; Marques, Alan Lima; Terra, Bruno Souza; Oliveira, Bruno Ribeiro Ramalho

2012-01-01

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Digital Forensics in VoIP networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

With VoIP being deployed on large scale, forensic analysis of captured VoIP traffic is of major practical interest. In this paper, we present a new fingerprinting approach that identifies the types of devices (name, version, brand, series) in captured VoIP traffic. We focus only on the signaling pla...

François, Jérôme; State, Radu; Engel, Thomas; Festor, Olivier

47

Investigation of VoIP and implementation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Voice over Internet Protocol (VoIP) is the technology used to transmit conversations digitally over the Internet. VoIP is being adopted globally and changing the landscape of telecommunications for businesses and consumers. This thesis describes the investigation of VoIP and how it compares to trad...

Ede, Aghedo

48

Selección de una levadura para la producción de biomasa: crecimiento en suero de queso  

Directory of Open Access Journals (Sweden)

Full Text Available El presente proyecto se realizó con el objetivo de recomendar una especie de levadura para la producción de biomasa, utilizando como sustrato el suero de leche del proceso de elaboración de queso blanco tipo Turrialba. Se compararon las especies Kluyveromyces marxianus, Candida kefyr y Saccharomyces cerevisiae por medio de su crecimiento en un sistema de fermentación por lotes. Se determinó el tiempo de fermentación, la productividad total y el contenido de proteína de la biomasa. Al comparar la variación en el tiempo según la levadura utilizada, se obtuvo diferencias significativas (p ? 0,05). Las levaduras K. marxianus y C. kefyr presentaron un tiempo de 19 y 18 horas, respectivamente y S. cerevisiae, un tiempo de 24 horas. Con respecto a la productividad total de biomasa, la especie K. marxianus presentó un valor de 0,22 g/lxh, resultando significativamente diferente (p ? 0,05) a las especies C. kefyr y S. cerevisiae, para las cuales se obtuvieron productividades de 0,14 y 0,13 g/lxh. La variación en el contenido de proteína de acuerdo con la levadura utilizada no resultó significativo (p ? 0,05). Para la especie K. marxianus se obtuvo un contenido de proteína de 32%, 34% para C. kefyr y 35% para S. cerevisiae. Se seleccionó la especie de levadura Kluyveromyces marxianus para la producción de proteína unicelular, por presentar un menor tiempo de fermentación, mayor productividad e igual contenido proteico de la biomasa que las otras levaduras, además de facilidades de utilización

Wendy Zumbado-Rivera; Patricia Esquivel-Rodríguez; Eric Wong-González

2006-01-01

49

Biomasa y densidad de dos especies de pastos marinos en el sur de Quintana Roo, México  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La biomasa y productividad de una comunidad de pastos marinos es útil para determinar el estado ecológico de la costa. Se comparó la biomasa foliar y la densidad de vainas en praderas de Thalassia testudinum Banks & Sol. ex K. D. Koenig, en dos ambientes de la costa del Caribe mexicano (N= 6 cuadrantes/sitio) en Noviembre de 1998. Los valores de vainas y biomasa foliar fueron más bajos en la pradera asociada al manglar, que en la pradera establecida en una laguna arre (more) cifal. Esto probablemente se deba a que las hojas del manglar tuvieron porcentaje más alto de epífitas. Por otro lado, T. testudinum tuvo mayor biomasa que Syringodium filiforme Kütz en la laguna arrecifal. Abstract in english The biomass and productivity of a seagrass community are useful for determining the ecological status of the coast. Leaf biomass and shoot density in beds of Thalassia testudinum Banks & Sol. ex K. D. Koenig, were compared for two environments in the Mexican Caribbean coast (N= 6 quadrants/site) in November 1998. Shoot and leaf biomass values were lower in the mangrove-associated meadow than in the reef lagoon meadow. This could be related to the higher percentage of epip (more) hytes on mangrove leaves. In addition, T. testudinum had more biomass than Syringodium filiforme Kütz in the reef lagoon.

Gutiérrez-Aguirre, Martha Angélica; de la Fuente-Betancourt, María Gabriela; Cervantes-Martínez, Adrián

2000-06-01

50

Acumulación de biomasa y nutrimentos en plantaciones de palmito en Guápiles, Costa Rica  

Directory of Open Access Journals (Sweden)

Full Text Available Se cuantificó la producción de biomasa y nutrimentos en 2 plantaciones de pejibaye para palmito (Bactris gasipaes Kunth) de 4 y 8 años, mediante la estimación mensual del peso seco de palmitos cosechados y sus residuos (hojas, cáscaras, rebrotes), durante un período de 52 semanas consecutivas en Guápiles, Costa Rica. Adicionalmente, se determinó la extracción de N, P, K, Ca y Mg en todos los componentes de la planta en cada muestreo mensual. También se realizó un muestreo destructivo al final de las 52 semanas para estimar la biomasa aérea y remanente y su contenido de nutrimentos. A pesar de que hubo diferencias estacionales en la producción de palmitos y rebrotes durante el año, ambas plantaciones presentaron rendimientos acumulativos de número de palmitos y producción de biomasa muy similares al final de los 12 meses. Con base en el promedio de las 2 plantaciones, la producción de materia seca cosechada fue de 13,1 t ha-1, y sólo el 11% fue removido del campo, con la producción de 11214 palmitos y sus cáscaras. Al comparar la biomasa en la vegetación remanente con lo cosechado en forma acumulada se encontró que el

Eloy Molina; Alfredo Alvarado; Jimmy Boniche; Thomas J. Smyth

2002-01-01

51

Biomasa y densidad de dos especies de pastos marinos en el sur de Quintana Roo, México  

Directory of Open Access Journals (Sweden)

Full Text Available La biomasa y productividad de una comunidad de pastos marinos es útil para determinar el estado ecológico de la costa. Se comparó la biomasa foliar y la densidad de vainas en praderas de Thalassia testudinum Banks & Sol. ex K. D. Koenig, en dos ambientes de la costa del Caribe mexicano (N= 6 cuadrantes/sitio) en Noviembre de 1998. Los valores de vainas y biomasa foliar fueron más bajos en la pradera asociada al manglar, que en la pradera establecida en una laguna arrecifal. Esto probablemente se deba a que las hojas del manglar tuvieron porcentaje más alto de epífitas. Por otro lado, T. testudinum tuvo mayor biomasa que Syringodium filiforme Kütz en la laguna arrecifal.The biomass and productivity of a seagrass community are useful for determining the ecological status of the coast. Leaf biomass and shoot density in beds of Thalassia testudinum Banks & Sol. ex K. D. Koenig, were compared for two environments in the Mexican Caribbean coast (N= 6 quadrants/site) in November 1998. Shoot and leaf biomass values were lower in the mangrove-associated meadow than in the reef lagoon meadow. This could be related to the higher percentage of epiphytes on mangrove leaves. In addition, T. testudinum had more biomass than Syringodium filiforme Kütz in the reef lagoon.

Martha Angélica Gutiérrez-Aguirre; María Gabriela de la Fuente-Betancourt; Adrián Cervantes-Martínez

2000-01-01

52

VoIP and TIPHON  

UK PubMed Central (United Kingdom)

Voice over the Internet Protocol (VoIP) is the catalyst for bandwidth on demand, which willopen the way for numerous, yet-to-be-invented applications, further changing the way peopleand businesses interact in the future. This paper presents the status of the VoIP industry andidentifies the driving forces including convergence, applications, finance, policy and regulation,technology, and standards. Further, this paper investigates the status of the Telecommunicationsand Internet Protocol Harmonization Over Networks (TIPHON) project. TIPHON is a globalinitiative sponsored by the European Telecommunications Standards Institute (ETSI) to addressconvergence issues and is being designed to support a market for voice communication andrelated multimedia aspects between users in IP-based networks and users in circuit-switchedenvironments.2. Driving Forces2.1. ConvergenceThere is broad agreement in industry, academia, and the government that developments in digitalelectronics and...

Wan Han Chan; Cliff C. Faurer; Douglas L. Haskins; Nancy K. Schmidt

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Performance of VoIP on HSDPA  

DEFF Research Database (Denmark)

This paper provides packet scheduler design and performance simulations for running VoIP services over high-speed downlink packet access (HSDPA) in WCDMA. The main challenge of supporting VoIP service on HSDPA is the tight delay requirement combined with the small VoIP packet size. A packet scheduler design incorporating VoIP packet aggregation and user multiplexing is proposed and the VoIP capacity is studied for a macro-cellular environment. Results are obtained for different delay budgets and packet scheduling settings, using either blind round robin or a slightly modified version of proportional fair scheduling. For proportional fair scheduling with code-multiplexing of 4-users, the downlink VoIP cell capacity on HSDPA is found to be in the range 72-104 users depending on whether the delay budget for the Node-B scheduling and user reception equals 80 ms or 150 ms, respectively.

Wang, Bang; Pedersen, Klaus I.

2005-01-01

54

Biomasa e índices fisiológicos en chile morrón cultivado en altas densidades  

Directory of Open Access Journals (Sweden)

Full Text Available Se estudió la acumulación y distribución de biomasa y su relación con algunos indicadores de eficiencia fisiológica en chile morrón (Capsicum annum L.) cv. ?Ariane?, cultivado en invernadero e hidroponía en distintas condiciones de manejo. Se manejaron tres densidades de población: 8 y 14 plantas/m2 despuntadas por encima de la tercera y cuarta bifurcación respectivamente (D8 y D14), y un testigo a 3.3 plantas/m2 sin despunte. Se hicieron cuatro muestreos: en transplante, amarre del primer fruto (40 días después del transplante [ddt]), crecimiento de los primeros frutos (70 ddt), y al final de la cosecha (158 ddt). La tasa de fotosíntesis se midió en hojas bien iluminadas con un analizador de gases al infrarrojo, en cuatro ocasiones (a los 40, 54, 68 y 82 ddt). Después de los 40 ddt, el testigo acumuló más biomasa por planta que las otras densidades de población, debido a su mayor área foliar. Sin embargo, por tener mayor densidad, D8 y D14 produjeron mayores índices de área foliar, lo que se correlacionó directamente con mayores cantidades de biomasa y rendimiento de frutos/m2. La tasa de fotosíntesis se incrementó durante el crecimiento de los primeros frutos en alrededor de 65 % (de 12 a 20 µmol CO2 m-2 s-1).

Nicacio Cruz-Huerta; Joaquu00EDn Ortiz-Cereceres; Felipe Su00E1nchez del Castillo; Maru00EDa del Carmen Mendoza-Castillo

2005-01-01

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PRODUCCIÓN DE BIOMASA DE Artemia franciscana Kellogg 1906 UTILIZANDO DIFERENTES DIETAS  

Directory of Open Access Journals (Sweden)

Full Text Available Se realizó el cultivo semiintensivo de Artemia franciscana, cepa Perú, utilizando diferentes dietas en base a microalgas e insumos alimenticios que forman parte de algunos ingredientes que se utilizan para preparar alimento formulado de peces y crustáceos, con el fin de determinar la factibilidad del uso de estos para la obtención de biomasa de adultos. El estudio se ejecutó en base a un diseño experimental completamente aleatorio con 7 tratamientos y 3 réplicas cada uno, aplicándose a los datos obtenidos un Análisis de Varianza de una vía (ANOVA) y la prueba de Tukey para establecer diferencias significativas entre los tratamientos. Los resultados del análisis próximal de las dietas, mostraron que la harina de soya presentó la cantidad de proteínas requerida por A. franciscana durante su crecimiento (34.33 %), igualmente con esta dieta se obtuvo la mejor tasa de crecimiento (0.19), biomasa más alta (113.33 g) y el mejor Factor de Conversión Alimenticia (1.4). Así mismo la biomasa de A. franciscana producida con harina de soya, presentó un nivel de proteínas adecuado para la maduración de reproductores de crustáceos (53.38 %).

Rosario Cisneros; Enrique Vinatea

2009-01-01

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Maximal endurance time at VO2max.  

UK PubMed Central (United Kingdom)

INTRODUCTION: There has been significant recent interest in the minimal running velocity which elicits VO2max. There also exists a maximal velocity, beyond which the subject becomes exhausted before VO2max is reached. Between these limits, there must be some velocity that permits maximum endurance at VO2max, and this parameter has also been of recent interest. This study was undertaken to model the system and investigate these parameters. METHODS: We model the bioenergetic process based on a two-component (aerobic and anaerobic) energy system, a two-component (fast and slow) oxygen uptake system, and a linear control system for maximal attainable velocity resulting from declining anaerobic reserves as exercise proceeds. Ten male subjects each undertook four trials in random order, running until exhaustion at velocities corresponding to 90, 100, 120, and 140% of the minimum velocity estimated as being required to elicit their individual VO2max. RESULTS: The model development produces a skewed curve for endurance time at VO2max, with a single maximum. This curve has been successfully fitted to endurance data collected from all 10 subjects (R2 = 0.821, P < 0.001). For this group of subjects, the maximal endurance time at VO2max can be achieved running at a pace corresponding to 88% of the minimal velocity, which elicits VO2max as measured in an incremental running test. Average maximal endurance at VO2max is predicted to be 603 s in a total endurance time of 1024 s at this velocity. CONCLUSION: Endurance time at VO2max can be realistically modeled by a curve, which permits estimation of several parameters of interest; such as the minimal running velocity sufficient to elicit VO2max, and that velocity for which endurance at VO2max is the longest.

Morton RH; Billat V

2000-08-01

57

VoIP to the Rescue  

Science.gov (United States)

Voice over Internet Protocol (VoIP) is everywhere. The technology lets users make and receive phone calls over the Internet, transporting voice traffic alongside data traffic such as instant messages (IMs) and e-mail. While the number of consumer customers using VoIP increases every week, the technology is finding its way into K-12 education as…

Milner, Jacob

2005-01-01

58

Rapid hydrothermal synthesis of VO2 (B) and its conversion to thermochromic VO2 (M1).  

UK PubMed Central (United Kingdom)

The present study provides a rapid way to obtain VO2 (B) under economical and environmentally friendly conditions. VO2 (B) is one of the well-known polymorphs of vanadium dioxide and is a promising cathode material for aqueous lithium ion batteries. VO2 (B) was successfully synthesized by rapid single-step hydrothermal process using V2O5 and citric acid as precursors. The present study shows that phase-pure VO2 (B) polytype can be easily obtained at 180 °C for 2 h and 220 °C for 1 h, that is, the lowest combination of temperature and duration reported so far. The obtained VO2 (B) is characterized by X-ray powder diffraction, high-resolution scanning electron microscopy, and Fourier transform infrared spectroscopy. In addition, we present an indirect way to obtain VO2 (M1) by annealing VO2 (B) under vacuum for 1 h.

Popuri SR; Miclau M; Artemenko A; Labrugere C; Villesuzanne A; Pollet M

2013-05-01

59

Security in VoIP  

Directory of Open Access Journals (Sweden)

Full Text Available VoIP relies on packet switching, similar to the way that e-mails are sent over the Internet. The technology breaks down a voice call into bite-size information packets. Instead of keeping the switch open all the time, the information is sent and received as needed, allowing excess line capacity to be used to carry other data. When the voice data arrives at its destination, it's reassembled into a voice call. As voice over IP services grow in popularity, the potential for viruses, worms and other security threats aimed at the technology also will grow. The current paper's purpose is presenting several security solutions and applying them to integrated systems at an economical and social level.

Floriana GEREA

2012-01-01

60

Efecto de nutrientes sobre la producción de biomasa del hongo medicinal Ganoderma lucidum  

Directory of Open Access Journals (Sweden)

Full Text Available  Effect of nutrients in the biomass production of the medicinal mushroom Ganoderma lucidum Título corto: Efecto de nutrientes sobre la producción de G. lucidumResumen El hongo Ganoderma lucidum, en los constituyentes de su biomasa, tiene compuestos con propiedades benéficas para la salud; es por esto que el conocimiento de las condiciones nutricionales adecuadas para su crecimiento permitirá su producción industrial y a bajo costo. En este trabajo se evaluó a nivel de matraz el efecto de la relación C/N, y la presencia de diferentes fuentes de carbono, nitrógeno y micronutrientes sobre la producción de biomasa. Empleando glucosa y peptona como fuentes de carbono y nitrógeno, respectivamente, se encontró una relación C/N óptima de 16,7:1 para la cual la máxima producción de biomasa fue de 25 g/L. Manteniendo esta relación C/N, y sustituyendo la glucosa por lactosa o harina de cebada y la peptona por extracto de levadura, la producción de biomasa se incrementó a 35 g/L. En presencia de harina de cebada la adición al medio de cultivo de sales de Mg y K, y de tiamina, no generó un mayor incremento en la producción de biomasa. La producción de biomasa de G. lucidum se ve favorecida por la presencia en el medio de cultivo de relaciones C/N cercanas a las reportadas conforme a la composición típica de los hongos, así como por la presencia de sustratos complejos como la harina de cebada que le aportan además de la fuente de carbono micronutrientes necesarios para su desarrollo. Palabras clave: harina de cebada, relación C/N, micronutrientes, fuentes de carbono, fuentes de nitrógeno.  AbstractGanoderma lucidum fungus has some biomass components with beneficial health properties. The knowledge about its nutritionals requirements for growing will favor its industrial production at lower cost. In this work, the effect of C/N ratio, the presence of different carbon, nitrogen and micronutrients sources, on fungal biomass production, were evaluated. Using glucose and peptone as carbon and nitrogen sources, respectively, an optimal C/N ratio of 16,7:1 was found, for which the maximal biomass production was 25 g/L. Replacing glucose by lactose or barley flour and peptone by yeast extract at the same C/N ratio, the biomass production was enhanced to 35 g/L. With barley flour in the culture medium, the presence of Mg and K salts and thiamine did not turn out into a major increase of biomass. The G. lucidum biomass production is promoted by C/N ratios in the culture medium nearly equivalent to that found in the fungus, as well as the presence of complex substrates as barley flour which, additionally, contributes with important micronutrients along with the carbon source.  Key words: Barley flour, C/N ratio, micronutrients, carbon sources, nitrogen sources.

Torres López Ana María; Quintero Díaz Juan Carlos; Atehortua Garcés Lucía

2011-01-01

 
 
 
 
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Estudio de la oxidación a elevada temperatura de ocho aleaciones en atmósferas de combustión de biomasa  

Directory of Open Access Journals (Sweden)

Full Text Available The combustion of biomass, especially wheat straw, generates very corrosive media particularly near the superheater tubes. Chlorine is known to be the main corrosive agent in biomass-fired plants. This paper focuses on the study of the corrosivity of such environments composed of gases and ashes, at high temperature, on eight commercial alloys with different chromium and nickel contents. These have been: AISI 347 CG (1.4550), AISI 347 FG(1.4550), AISI 316LN (1.4910), ESSHETE 1250 (1.4982), AC 66 (1.4877), X20CrMoV12:1 (1.4922) and AISI 347 coated with Inconel 625 and Inconel 686. Corrosion tests in the boiler have been performed during 8.000 h and 15.000 h at temperatures between 500 °C y 550 °C in the biomass plant of Sangüesa (Navarra, Spain). Experimental results showed an unacceptable behaviour far the martensitic steel, acceptable far the austenitics and good far the inconels. The appearance of the corrosion attack was also investigated to obtain understanding of the corrosion mechanism. The corrosion mechanism by molten salts has been rejected. The active oxidation corrosion mechanism has been proposed as the most probable in order to interpretate the corrosion behaviour of these materials in these environments.La combustión de biomasa, especialmente de paja de cereal, genera un ambiente muy corrosivo, particularmente, cerca de los tubos sobrecalentadores. El cloro es el principal agente corrosivo en las plantas de biomasa. Este trabajo se centra en comprobar el comportamiento de ocho aleaciones comerciales en una ambiente de combustión de biomasa. Los materiales estudiados han sido las siguientes: AISI 347 CG (1.4550), AISI 347 FG (1.4550), AISI 316LN (1.4910), ESSHETE 1250 (1.4982), AC 66 (1.4877), X20CrMoV12:1 (1.4922) y AISI 347 recubiertos con Inconel 625 e Inconel 686. Los ensayos se han realizado en la caldera de la planta de biomasa de Sangüesa (Navarra, España) durante 8.000 y 15.000 h a una temperatura de 500-550 °C. Los resultados indican un buen comportamiento de los aceros inoxidables austeníticos y de las aleaciones de Inconel, mientras que el del acero martensítico no ha sido aceptable. Se ha propuesto el mecanismo conocido como “oxidación activa” para interpretar el comportamiento a la corrosión de estos materiales en estos medios.

Berlanga-Labari, C.; J. Fernández-Carrasquilla, J.

2008-01-01

62

Comprehensive Comparison of VoIP SIP Protocol Problems and Cisco VoIP System  

Directory of Open Access Journals (Sweden)

Full Text Available Voice over IP (VoIP), use of the packet switched internet for telephony, has improved substantially in the past few years. On the other hand, VoIP has many challenges that do not exist in the public switched telephone network (PSTN), a circuit switched system. VoIP is an application running on the internet, and therefore inherits the internet’s security issues. It is important to realise that VoIP is a relatively young technology, and with any new technology, security typically improves with maturity. This paper provides a comprehensive comparison of a VoIP SIP protocol and CISCO VoIP system. The comparison involves the investigation of the vulnerabilities that target both systems and how secure each system is. With this comparison we present our conclusion on which system is more secure.

TALAL AL-KHAROBI; Mohmmed Abduallah Al-Mehdhar

2012-01-01

63

TERTIARY EDUCATION IN THE KNOWLEDGE-BASED SOCIETY / Terciárne vzdelávanie vo vedomostnej spolo?nosti  

Directory of Open Access Journals (Sweden)

Full Text Available The statement describes basic knowledge focused on the tertiary education in the knowledge-based society with positive and negative implications of transnational education.V príspevku sa uvádzajú základné poznatky o terciárnom vzdelávaní vo vedomostnej spolo?nosti s osobitným zrete?om na pozitívne a negatívne dôsledky transnárodného vzdelávania.

Poláková Helena; Plav?an Peter

2008-01-01

64

Análisis Exergético de la Gasificación de Biomasa Exergy Analysis of Biomass Gasification  

Directory of Open Access Journals (Sweden)

Full Text Available El objetivo de este estudio fue realizar el análisis exergético de la gasificación de biomasa residual con la finalidad de obtener energía útil. Se desarrolló un modelo para la gasificación de biomasa basado en el equilibrio químico de las reacciones. Este modelo permite predecir la evolución de la composición del gas de síntesis en función de la temperatura, las presiones y la composición elemental de los residuos del proceso de extracción de aceite de palma y orujo de lavado de uva (hidrogeno, oxigeno, carbono y nitrógeno), como también hacer un análisis exergético. Se encontró que independiente del agente gasificante, la concentración de monóxido de carbono e hidrógeno tienden a incrementar significativamente a altas presiones y elevadas temperaturas. Además, se muestra que la eficiencia exergética incrementa con la temperatura y disminuye con el aumento de la relación aire/combustible.This paper shows the exergy analysis applied to the gasification process of residual biomass with the purpose of obtaining useful energy. A model for the biomass gasification based on chemical equilibrium of the reactions is proposed. The model allows predicting the syngas composition as a function of temperature, pressure and ultimate analysis of palm oil and grapevine pruning waste (determining hydrogen, oxygen, carbon and nitrogen). It was found that the carbon monoxide and hydrogen concentration significantly increase at high pressure and temperature independently of the gasifying agent. Furthermore, it was also noticed that the exergy efficiency increases as temperature increases, and decreases as the relative fuel/air ratio increases.

Jorge M Mendoza; Antonio J Bula; Rafael D Gómez; Lesmes A Corredor

2012-01-01

65

VoIP technology comes of age.  

Science.gov (United States)

Cabling specialist Connectix examines the growing potential for healthcare sector use of VoIP technology and highlights the importance of correct cabling infrastructure as a carrier of both voice and high-speed data traffic. PMID:18494421

2008-04-01

66

VoIP technology comes of age.  

UK PubMed Central (United Kingdom)

Cabling specialist Connectix examines the growing potential for healthcare sector use of VoIP technology and highlights the importance of correct cabling infrastructure as a carrier of both voice and high-speed data traffic.

2008-04-01

67

A Comprehensive Secure VoIP Solution  

Directory of Open Access Journals (Sweden)

Full Text Available VoIP represents the future of digital voice communications and many carriers are preparing for the VoIP revolution. However, a number of outstanding issues need to be settled. The most important are security, compression, packet size optimization, quality of service and performance in heterogeneous networks. We have addressed all of these issues [2, 3, 4, 5] and here we summarize our key findings in each of these areas.

Ashraf D. Elbayoumy; Simon Shepherd

2007-01-01

68

LACK - a VoIP Steganographic Method  

CERN Multimedia

The paper presents a new steganographic method called LACK (Lost Audio PaCKets Steganography) which is intended mainly for VoIP. The method is presented in a broader context of network steganography and of VoIP steganography in particular. The analytical results presented in the paper concern the influence of LACK's hidden data insertion procedure on the method's impact on quality of voice transmission and its resistance to steganalysis.

Mazurczyk, Wojciech

2008-01-01

69

The VO2 slow component in swimming.  

UK PubMed Central (United Kingdom)

All studies on the oxygen uptake (VO2) slow component have been carried out for the sporting disciplines of cycling or running, but never for swimming. Considering that front crawl swimming is a sport discipline that is fundamentally different from both running and cycling, the aim of this study was to verify whether this slow component also appears in swimming. Six elite pentathletes were tested in a swimming flume while front crawl swimming to exhaustion. Swimming velocity for the slow component test was determined as v50% delta = CV + [vVO2peak - CV)/2], where CV is the critical velocity and vVO2peak the lowest velocity at which peak VO2 occurred. To set the subject's CV, expressed as the slope of a straight line that describes the correlation between swimming distance and time, the record times over three swimming distances were recorded in a 50 m swimming pool. The vVO2peak was measured by means of an incremental test in the swimming flume. Gas exchange was measured by means of a telemetric metabolimeter (K4 RQ, Cosmed, Italy) that was connected to a snorkel. The slow component was found in all subjects, with a mean (SD) value of 239 (194) mlO2.min-1. Therefore, although front crawl swimming is fundamentally different from both running and cycling, it appears that it also incurs a VO2 slow component. The origin of this phenomenon, however, is even more uncertain than for the other sport disciplines.

Demarie S; Sardella F; Billat V; Magini W; Faina M

2001-01-01

70

The Armenian Virtual Observatory, ArVO  

Science.gov (United States)

The Armenian Virtual Observatory (ArVO) is a project of the Byurakan Astrophysical Observatory (BAO) aimed at construction of a modern system for astronomical data archiving, extraction, acquisition, reduction, use and publication. ArVO is based on the Digitized First Byurakan Survey (DFBS) and is the Armenian contribution to the International Virtual Observatories Alliance (IVOA). ArVO's main goal is to create an interoperability data system for Armenian astronomy based on the Armenian and world astronomy resources and according to IVOA standards. Beside the DFBS, ArVO will combine all other Byurakan archival data and modern observations from the 2.6m telescope. ArVO includes also some science projects, such as the development of an automatic identification procedure using the low-dispersion spectra and all other available databases, and optical identification of X-ray, IR and radio sources; development of an automatic search procedure for modeled objects, and automatic search for new bright AGN in the DFBS. ArVO web page is available at http://www.aras.am/arvo.htm.

Mickaelian, A. M.

2006-07-01

71

Biomassa de rotíferos em ambientes dulcícolas: Revisão de métodos e fatores influentes/ Rotifer biomass in freshwater environments: Review of methods and influencing factors/ Biomasa de rotíferos en ambientes dulciacuícolas: Revisión de métodos y factores influyentes  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A biomassa de uma comunidade aquática fornece informações quantitativas da matéria orgânica disponível nos diferentes níveis tróficos. As dificuldades metodológicas para se estimar a biomassa zooplanctônica explicam os poucos estudos existentes, principalmente no Brasil. Neste estudo objetiva-se descrever as metodologias mais utilizadas na estimativa da biomassa de rotíferos, analisar suas vantagems e desvantagems, comparar resultados obtidos com cada técnica, (more) e investigar alguns fatores que influenciam sua biomassa. A estimativa mais utilizada é a determinação do volume, a partir de dimensões lineares. Estudos apontam que os valores estimados da biomassa de rotíferos podem variar de acordo com as metodologias de amostragem, preservação dos indivíduos, características limnológicas dos ambientes e genotípicas dos indivíduos, predação, disponibilidade de alimento, além da sazonalidade. Todos esses fatores evidenciam a necessidade de se estimar a biomassa ao invés da utilização de equações já descritas na literatura, bem como a importância de se descrever detalhadamente a metodologia utilizada em cada amostragem, e algumas características limnológicas dos ambientes estudados. Abstract in spanish La biomasa de una comunidad acuática provee información cuantitativa de la materia orgánica disponible en los diferentes niveles tróficos. Las dificultades metodologías en la estimación de la biomasa zooplanctónica explican los pocos estudios existentes, principalmente en Brasil. Se describen los métodos más utilizados en la estimación de la biomasa de rotíferos, se analizan sus ventajas y desventajas, se comparan los resultados obtenidos con cada técnica, y s (more) e discuten algunos factores que influyen en su biomasa. El método más utilizado es la determinación del biovolumen, obtenido a partir de las dimensiones lineales de los rotíferos. La mayor parte de los estudios sugieren que la biomasa de rotíferos varía de acuerdo con los métodos de muestreo, la conservación de los individuos, la depredación y la disponibilidad de alimentos, además de la estacionalidad. Todos estos factores evidencian la necesidad de estimar la biomasa en lugar de utilizar ecuaciones ya descritas en la literatura, así como la importancia de describir el método utilizado en cada muestreo y algunas características limnológicas de los ambientes estudiados. Abstract in english The biomass of an aquatic community provides quantitative information from available organic matter in different trophic levels. The methodological difficulties in estimating zooplankton biomass explain the scarcity of existing studies, particularly in Brazil. The most used methodologies for rotifer biomass estimation are described and their advantages and disadvantages analyzed. Results obtained with the different techniques are compared and some factors influencing the (more) biomass are discussed. The most commonly used methodology is the biovolume, calculated from rotifer linear dimensions. Studies point out that rotifers biomass vary according to sampling methodologies, individual preservation, environments limnological characteristics, individual genotypical characteristics, predation, food resource availability and seasonality. All these factors emphasize the importance of estimating biomass instead of using equations already described in the literature, as well as the importance to describe in detail the methodology employed in each sampling and some limnological features of the studied environments.

Christian Rossa, Dayane; Costa Bonecker, Claudia; Junio Fulone, Leandro

2007-04-01

72

COMPUTER SIMULATION IN THE ELECTRONICS EDUCATION FOCUSED TO INCREASE THE SPECIAL HIGH SCHOOL STUDENTS MOTIVATION II. / Po?íta?ové modelovanie vo výu?be elektroniky zamerané na zvýšenie motivácie žiakov SOŠ II  

Directory of Open Access Journals (Sweden)

Full Text Available The authors interpret the particular results of their research in this contribution. It is focused to the impact of computer model on education. Anticipated result is the higher efficiency of special education here. This aim is achieved by application of motivation relations in coherence with exploitation easy reached free software. At the same time here is the latest technology, based on the computer design of circuits, applied here.Tento príspevok je pokra?ovaním prvej ?asti, ktorá bola zameraná na zvýšenie motivácie prostredníctvom bezplatne získate?ného softvéruzo siete internet. Obsahom druhej ?asti príspevku je súbor ukážok jednosmernej, striedavej a transiert analýzy elektronických obvodov.

ArpᚠJúlius; Soták Vladimír

2008-01-01

73

Revisión sobre la corrosión de tubos sobrecalentadores en plantas de biomasa  

Directory of Open Access Journals (Sweden)

Full Text Available The design of new biomass-fired power plants with increased steam temperature raises concerns of high-temperature corrosion. The high potassium and chlorine contents in many biomasses, specially in wheat straw, are potentially harmful elements with regard to corrosion. Chlorine may cause accelerated corrosion resulting in increased oxidation, metal wastage, internal attack, void formations, and loose non-adherent scales. The most severe corrosion problems in biomass-fired systems are expected to occur due to Cl-rich deposits formed on superheater tubes. In the first part of this revision the corrosion mechanism proposed are described in function of the conditions and compounds involved. The second part is focused on the behaviour of the materials tested so far in the boiler and in the laboratory. First the traditional commercial alloys are studied and secondly the new alloys and the coatingsEn el diseño de plantas de biomasa es muy importante tener en cuenta la temperatura del vapor para no tener problemas de corrosión. Esto, es debido al alto contenido de potasio y cloro que tienen la mayoría de los biocombustibles y, en especial, la paja de cereal. El objetivo de esta revisión es condensar el conocimiento actual sobre la corrosión de los sobrecalentadores a altas temperaturas provocada por compuestos clorados en plantas de biomasa. El cloro puede causar corrosión acelerada debido a la pérdida de metal del sobrecalentador, ataque interno y formación de capas de óxidos no adherentes. Los problemas de corrosión más severos en una caldera de biomasa se producen en los depósitos formados sobre los tubos sobrecalentadores. En la primera parte de esta revisión, se describen los mecanismos de corrosión propuestos en función de las condiciones de trabajo predominantes en la caldera. La segunda parte, se centra en revisar los estudios realizados para comprobar el comportamiento de los materiales mediante ensayos realizados en la caldera y en el laboratorio. En primer lugar, se describen las investigaciones realizadas sobre aleaciones convencionales y después las realizadas sobre las aleaciones desarrolladas en los últimos años y recubrimientos.

Berlanga-Labari, C.; Fernández-Carrasquilla, J.

2006-01-01

74

Proceso de gasificación de biomasa: una revisión de estudios teórico- experimentales/ Biomass gasification process: theoretical and experimental studies a review  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La situación energética y medioambiental mundial hace que la generación de energía mediante sistemas basados en energías renovables tome cada vez una mayor relevancia. Estos sistemas tienen una doble ventaja ya que posibilitan la diversificación energética y reducen la dependencia del petróleo a la vez que se disminuyen las emisiones globales de CO2. La biomasa es uno de los recursos energéticos con mayor potencial tanto en países desarrollados como emergentes p (more) ero sigue sin sufrir el desarrollo esperado. La gasificación de biomasa es uno de los sistemas con gran potencial ya que permite la generación tanto de energía térmica como eléctrica, mediante tecnologías de bajo costo como los gasificadores de lecho fijo (potencias medias- bajas), o reactores de lecho fluidizado con tecnología más exigente y con mayor capacidad de generación. La transformación de la biomasa en un combustible gaseoso, aprovechable en motores de combustión interna alternativos o en turbinas de gas como combustible, exige que la biomasa atraviese varios procesos termoquímicos, compuestos por reacciones endotérmicas (secado, devolatilización y reducción) y exotérmicas (oxidación de volátiles y carbón). La selección de un gasificador requiere conocer las propiedades de la biomasa, mientras que el diseño del mismo exige conocer el fenómeno termoquímico por completo. El objetivo de este trabajo es presentar una revisión actualizada de los diferentes planteamientos tanto teóricos como experimentales desarrollados para estudiar el proceso de gasificación de biomasa, tanto en lecho fijo como en lecho fluidizado, con miras a diseñar gasificadores de biomasa. Abstract in english Each day the energy systems relying on renewable resources are more relevant in the world energy politics due to the fossil energy and environmental crisis. These systems increase energy resources of countries, reduce the oil dependency, and diminish CO2 global emissions. Biomass is one of the renewable resources with higher potential in developing and developed countries. Biomass gasification has huge possibilities to be developed. Such as fixed bed gasifiers, or fluidiz (more) ed bed reactors with more technology demanding and more power capacity. Biomass transformation in a gaseous fuel to be used in a reciprocating internal combustion engine or gas turbines requires that biomass passes through several thermochemical stages. Endothermic reactions (drying, pyrolysis and reduction) and exothermic process (volatiles and carbon oxidation). To select a specific gasifier it is necessary to know biomass properties (chemical and physical), whereas to design a reactor it is necessary to know and understand the complete phenomena. The aim of this work is to show an actualized review about different theoretical and experimental approaches to study biomass gaification process in fixed and fluidized bed reactors in order to design biomass gasifiers.

Pérez, Juan; Borge, David; Agudelo, John

2010-03-01

75

Lattice relaxation and ferromagnetic character of (LaVO3)m/SrVO3superlattices  

Science.gov (United States)

The experimental observation that vanadate superlattices (LaVO3)m/SrVO3 show ferromagnetism up to room temperature (Lüders U. et al., Phys. Rev. B, 80 (2009) 241102(R)) is investigated by means of density functional theory, and the band structure for m = 5 and 6 is calculated. A buckling of the interface VO2 layers is found in both cases, but subtle differences in bond length lead to very different properties for even and odd values of m: in the even case, the two interface VO2 layers effectively decouple from the adjacent LaO layers due to a strong bond length enhancement. This results into a local inversion of the orbital occupancy and to the confinement of the charge carriers. In the odd case, the amplitude of the bond length variation is smaller, so that the charge carriers spill into the deeper-lying VO2 layers, and spin-polarised interfaces are obtained.

Schuster, Cosima; Lüders, Ulrike; Frésard, Raymond; Schwingenschlögl, Udo

2013-08-01

76

Crystal structure of ?-AgVO3 and phase relation of AgVO3  

International Nuclear Information System (INIS)

Phase relations of AgVO3 were studied by crystal structure analysis and thermal property measurement. Crystal structure of newly defined ?-AgVO3 was determined by XRD measurements. The structure analyzed is monoclinic [C2/c(number-sign 15)] and the crystal parameters are a = 10.437 angstrom, b = 9.897 angstrom, c = 5.532 angstrom, and ? = 99.69 degree, ?-AgVO3 is a metastable phase which can be formed by precipitation at an ambient temperature and/or when it is quenched from its melted state. It is also formed just below the melting point instantaneously when cooled slowly and frozen quickly. ?-AgVO3 is irreversibly transformed into ?-AgVO3 at around 200 C. The ?-phase is molten at 476 C

1999-02-01

77

Bioadsorción de Cadmio (II) en Solución Acuosa por Biomasas Fúngicas Biosorption of Cadmium (II) in Aqueous Solutions by Fungal Biomass  

Directory of Open Access Journals (Sweden)

Full Text Available Se determinó la bioadsorción de Cadmio (II) en solución por la biomasa celular de quince hongos, por el método colorimétrico de la ditizona. La biomasa de Mucor rouxii IM-80 fue más eficiente en la remoción de Cadmio (II) en solución (8.2 mg/g) seguida de M. rouxii mutante (7.1 mg/g), A. flavus I (5.9 mg/g) y Helminthosporium sp (5.4 mg/g). Para la biomasa de M. rouxii-IM-80, la mayor bioadsorción fue a pH= 5.0-6.0, a 28ºC durante 40 horas con 1.0 mg/200 mL de concentración inicial de Cadmio (II) y 80 mg/200 mL de biomasa celular. Se concluye que algunas biomasas fúngicas remueven eficientemente Cadmio (II) en solución y pueden utilizarse para descontaminar nichos acuáticos contaminados con este metalThe biosorption of dissolved Cadmium (II) using cellular biomass of 15 fungi, using a dithizone colorimetric method, was determined. The Mucor rouxii IM-80 biomass was more efficient in removing Cadmium (II) from solution (8.2 mg/g), followed by the M. rouxii mutant (7.1 mg/g), Aspergillus flavus I (5.9 mg/g) and Helminthosporium sp (5.4 mg/g) biomasses. The highest biosorption for M. rouxii IM-80 was at pH 5.0-6.0, at 28ºC for 40 h employing 1.0 mg/200mL of Cadmium (II) as initial concentration, and 80 mg/200 mL of fungal biomass. It was concluded that some fungal biomass efficiently removed Cadmium (II) from solution and could be used for decontamination of aquatic habitats polluted with this metal

Ismael Acosta; María de Guadalupe Moctezuma-Zárate; Juan F Cárdenas; Conrado Gutiérrez

2007-01-01

78

Bioadsorción de Cadmio (II) en Solución Acuosa por Biomasas Fúngicas/ Biosorption of Cadmium (II) in Aqueous Solutions by Fungal Biomass  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Se determinó la bioadsorción de Cadmio (II) en solución por la biomasa celular de quince hongos, por el método colorimétrico de la ditizona. La biomasa de Mucor rouxii IM-80 fue más eficiente en la remoción de Cadmio (II) en solución (8.2 mg/g) seguida de M. rouxii mutante (7.1 mg/g), A. flavus I (5.9 mg/g) y Helminthosporium sp (5.4 mg/g). Para la biomasa de M. rouxii-IM-80, la mayor bioadsorción fue a pH= 5.0-6.0, a 28ºC durante 40 horas con 1.0 mg/200 mL de c (more) oncentración inicial de Cadmio (II) y 80 mg/200 mL de biomasa celular. Se concluye que algunas biomasas fúngicas remueven eficientemente Cadmio (II) en solución y pueden utilizarse para descontaminar nichos acuáticos contaminados con este metal Abstract in english The biosorption of dissolved Cadmium (II) using cellular biomass of 15 fungi, using a dithizone colorimetric method, was determined. The Mucor rouxii IM-80 biomass was more efficient in removing Cadmium (II) from solution (8.2 mg/g), followed by the M. rouxii mutant (7.1 mg/g), Aspergillus flavus I (5.9 mg/g) and Helminthosporium sp (5.4 mg/g) biomasses. The highest biosorption for M. rouxii IM-80 was at pH 5.0-6.0, at 28ºC for 40 h employing 1.0 mg/200mL of Cadmium (II) (more) as initial concentration, and 80 mg/200 mL of fungal biomass. It was concluded that some fungal biomass efficiently removed Cadmium (II) from solution and could be used for decontamination of aquatic habitats polluted with this metal

Acosta, Ismael; Moctezuma-Zárate, María de Guadalupe; Cárdenas, Juan F; Gutiérrez, Conrado

2007-01-01

79

¿Controla la biomasa de pastos marinos la densidad de los peracáridos (Crustacea: Peracarida) en lagunas tropicales?  

Directory of Open Access Journals (Sweden)

Full Text Available Se analizó la variación en tiempo y espacio de los crustáceos peracáridos que habitan las praderas de Ruppia maritima del sistema lagunar de Alvarado, Veracruz, Golfo de México. El muestreo de esta asociación de crustáceos se realizó de diciembre de 1992 a noviembre de 1994. Los organismos se obtuvieron de 108 muestras recolectadas en seis sitios con R. maritima. La asociación de crustáceos incluyó 11 especies. Ocho especies en Amphipoda (Hourstonius laguna, Cerapus benthophilus, Apocorophium louisianum, Grandidierella bonnieroides, Leptocheirus rhizophorae, Gammarus mucronatus, Melita longisetosa y Haustorius sp.), una en Isopoda (Cassidinidea ovalis) y dos en Tanaidacea (Discapseudes holthuisi and Leptochelia savignyi). La taxocenosis, la densidad y la biomasa de estos organismos mostraron pulsos estacionales relacionados positivamente con la variación de la biomasa de R. maritima, la salinidad, los afluentes epicontinentales y las bocas de comunicación. Las especies C. ovalis, G. mucronatus, A. louisianum y D. holthuisi fueron componentes dominantes en la asociación de peracáridos.Does sea-grass biomass control the density of peracarids (Crustacea: Peracarida) in tropical lagoons? We analyzed the time-space variation of the peracarid crustaceans that inhabit seagrasses of the Alvarado Lagoon System, Veracruz, Gulf of Mexico. The organisms were collected from 108 samples in six sites with Ruppia maritima beds (December 1992 to November 1994). The assemblage was composed of 11 species. Eight species of Amphipoda (Hourstonius laguna, Cerapus benthophilus, Apocorophium louisianum, Grandidierella bonnieroides, Leptocheirus rhizophorae, Gammarus mucronatus, Melita longisetosa and Haustorius sp.), one of Isopoda (Cassidinidea ovalis) and two of Tanaidacea (Discapseudes holthuisi and Leptochelia savignyi) were identified. Taxocoenosis, density and biomass of peracarids showed seasonal pulses related to R. maritima biomass, salinity variation, epicontinental affluent and inlets. The species C. ovalis, G. mucronatus, A. louisianum and D. holthuisi were dominant. Rev. Biol. Trop. 55 (1): 43-53. Epub 2007 March. 31.

Ignacio Winfield; Sergio Cházaro-Olvera; Fernando Álvarez

2007-01-01

80

Análisis Exergético de la Gasificación de Biomasa/ Exergy Analysis of Biomass Gasification  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El objetivo de este estudio fue realizar el análisis exergético de la gasificación de biomasa residual con la finalidad de obtener energía útil. Se desarrolló un modelo para la gasificación de biomasa basado en el equilibrio químico de las reacciones. Este modelo permite predecir la evolución de la composición del gas de síntesis en función de la temperatura, las presiones y la composición elemental de los residuos del proceso de extracción de aceite de palm (more) a y orujo de lavado de uva (hidrogeno, oxigeno, carbono y nitrógeno), como también hacer un análisis exergético. Se encontró que independiente del agente gasificante, la concentración de monóxido de carbono e hidrógeno tienden a incrementar significativamente a altas presiones y elevadas temperaturas. Además, se muestra que la eficiencia exergética incrementa con la temperatura y disminuye con el aumento de la relación aire/combustible. Abstract in english This paper shows the exergy analysis applied to the gasification process of residual biomass with the purpose of obtaining useful energy. A model for the biomass gasification based on chemical equilibrium of the reactions is proposed. The model allows predicting the syngas composition as a function of temperature, pressure and ultimate analysis of palm oil and grapevine pruning waste (determining hydrogen, oxygen, carbon and nitrogen). It was found that the carbon monoxid (more) e and hydrogen concentration significantly increase at high pressure and temperature independently of the gasifying agent. Furthermore, it was also noticed that the exergy efficiency increases as temperature increases, and decreases as the relative fuel/air ratio increases.

Mendoza, Jorge M; Bula, Antonio J; Gómez, Rafael D; Corredor, Lesmes A

2012-01-01

 
 
 
 
81

The VO2 slow component in swimming.  

Science.gov (United States)

All studies on the oxygen uptake (VO2) slow component have been carried out for the sporting disciplines of cycling or running, but never for swimming. Considering that front crawl swimming is a sport discipline that is fundamentally different from both running and cycling, the aim of this study was to verify whether this slow component also appears in swimming. Six elite pentathletes were tested in a swimming flume while front crawl swimming to exhaustion. Swimming velocity for the slow component test was determined as v50% delta = CV + [vVO2peak - CV)/2], where CV is the critical velocity and vVO2peak the lowest velocity at which peak VO2 occurred. To set the subject's CV, expressed as the slope of a straight line that describes the correlation between swimming distance and time, the record times over three swimming distances were recorded in a 50 m swimming pool. The vVO2peak was measured by means of an incremental test in the swimming flume. Gas exchange was measured by means of a telemetric metabolimeter (K4 RQ, Cosmed, Italy) that was connected to a snorkel. The slow component was found in all subjects, with a mean (SD) value of 239 (194) mlO2.min-1. Therefore, although front crawl swimming is fundamentally different from both running and cycling, it appears that it also incurs a VO2 slow component. The origin of this phenomenon, however, is even more uncertain than for the other sport disciplines. PMID:11394260

Demarie, S; Sardella, F; Billat, V; Magini, W; Faina, M

82

VO2+ and Cu2+ Interactions with Ceftriaxone and Ceftizoxime. HPLC Kinetic Studies  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Estudos do mecanismo, das constantes cinéticas e termodinâmicas das interações de VO2+ e Cu2+ com Ceftriaxone e Ceftizoxime, na faixa de pH entre 2 e 5 e nas temperaturas de 30 º,40 º, 50 º e 60 ºC, usando HPLC em fase reversa e de troca iônica são descritos. Foram avaliados os efeitos de pH, temperatura e concentração dos íons na reação de hidrólise. Estudos de HPLC forneceram evidência satisfatória do mecanismo da reação. Mecanismos das reaçôes dos complexes de Cu2+ e VO2+ envolvem um complexo 1:1. Abstract in english Studies of the mechanism, kinetics and thermodynamic constants of VO2+ and Cu2+ Ceftriaxone and Ceftizoxime interactions at the pH range between pH 2 and 5 and at the temperatures of 30 º, 40 º, 50 º and 60 ºC, using reversed phase HPLC and ion exchange HPLC, are reported. The effects of pH, temperature and ion concentration on the hydrolysis reaction have been evaluated. HPLC studies provided satisfactory evidence of the reaction mechanism. Mechanisms for Cu2+ and VO2+ induced reactions involve a complex of 1:1 stoichiometry.

Doadrio, Antonio L.; Mayorga, Antonio; Orenga, Regina

2002-02-01

83

Fuzzing dans la sphère VoIP  

Digital Repository Infrastructure Vision for European Research (DRIVER)

La voix sur IP (VoIP) s'impose aujourd'hui comme l'une des technologies clefs de l'Internet actuel et futur. Dans cet article, nous partageons l'expérience pratique acquise ces deux dernières années par notre équipe de recherche sur l'automatisation des processus de découverte de vulnérabilités dans...

Abdelnur, Humberto; Festor, Olivier; State, Radu

84

How To: Be VoIP-Savvy  

Science.gov (United States)

Cablevision, Comcast, Verizon, and many other high-speed broadband Internet providers are now also offering telephone services through "Voice over Internet Protocol" (VoIP). This technology sends ordinary telephone calls over the Internet rather than over telephone lines. While impractical without the use of a broadband Internet connection, with…

Branzburg, Jeffrey

2005-01-01

85

VoIP in a Campus Environment  

Science.gov (United States)

Internet Protocol (IP) Telephony, or voice-over IP (VoIP), has proved to be a wise decision for many organizations. This technology crosses the boundaries of public and private networks, enterprise and residential markets, voice and data technologies, as well as local and long-distance services. The convergence of voice and data into a single,…

Young, Dan

2005-01-01

86

Is VoIP Worth It?  

Science.gov (United States)

School districts have by and large had great results implementing VoIP, which has become the conduit for delivering expanded functionality, achieving greater internal control, and gaining freedom from onerous monthly phone bills. But demonstrating a financial return on what is a substantial investment can be an elusive effort. The goal of…

Schaffhauser, Dian

2008-01-01

87

Security in VoIP-Current Situation and Necessary Development  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nowadays, VoIP is getting more and more popular. It helps company to reduce cost, extends service to remote area, produce more service opportunities, etc. Besides these advantages, VoIP also put forward security problems. In this paper, we introduce the popular protocols in VoIP and their security m...

Gao, Li Li

88

From hollow olive-shaped BiVO4 to n-p core-shell BiVO4@Bi2O3 microspheres: controlled synthesis and enhanced visible-light-responsive photocatalytic properties.  

UK PubMed Central (United Kingdom)

In this study, hollow olive-shaped BiVO(4) and n-p core-shell BiVO(4)@Bi(2)O(3) microspheres were synthesized by a novel sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-assisted mixed solvothermal route and a thermal solution of NaOH etching process under hydrothermal conditions for the first time, respectively. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy, Brunauer-Emmett-Teller surface area, and UV-vis diffuse-reflectance spectroscopy in detail. The influence of AOT and solvent ratios on the final products was studied. On the basis of SEM observations and XRD analyses of the samples synthesized at different reaction stages, the formation mechanism of hollow olive-shaped BiVO(4) microspheres was proposed. The photocatalytic activities of hollow olive-shaped BiVO(4) and core-shell BiVO(4)@Bi(2)O(3) microspheres were evaluated on the degradation of rhodamine B under visible-light irradiation (? > 400 nm). The results indicated that core-shell BiVO(4)@Bi(2)O(3) exhibited much higher photocatalytic activities than pure olive-shaped BiVO(4). The mechanism of enhanced photocatalytic activity of core-shell BiVO(4)@Bi(2)O(3) microspheres was discussed on the basis of the calculated energy band positions as well. The present study provides a new strategy to enhancing the photocatalytic activity of visible-light-responsive Bi-based photocatalysts by p-n heterojunction.

Guan ML; Ma DK; Hu SW; Chen YJ; Huang SM

2011-02-01

89

From hollow olive-shaped BiVO4 to n-p core-shell BiVO4@Bi2O3 microspheres: controlled synthesis and enhanced visible-light-responsive photocatalytic properties.  

Science.gov (United States)

In this study, hollow olive-shaped BiVO(4) and n-p core-shell BiVO(4)@Bi(2)O(3) microspheres were synthesized by a novel sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-assisted mixed solvothermal route and a thermal solution of NaOH etching process under hydrothermal conditions for the first time, respectively. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy, Brunauer-Emmett-Teller surface area, and UV-vis diffuse-reflectance spectroscopy in detail. The influence of AOT and solvent ratios on the final products was studied. On the basis of SEM observations and XRD analyses of the samples synthesized at different reaction stages, the formation mechanism of hollow olive-shaped BiVO(4) microspheres was proposed. The photocatalytic activities of hollow olive-shaped BiVO(4) and core-shell BiVO(4)@Bi(2)O(3) microspheres were evaluated on the degradation of rhodamine B under visible-light irradiation (? > 400 nm). The results indicated that core-shell BiVO(4)@Bi(2)O(3) exhibited much higher photocatalytic activities than pure olive-shaped BiVO(4). The mechanism of enhanced photocatalytic activity of core-shell BiVO(4)@Bi(2)O(3) microspheres was discussed on the basis of the calculated energy band positions as well. The present study provides a new strategy to enhancing the photocatalytic activity of visible-light-responsive Bi-based photocatalysts by p-n heterojunction. PMID:21171642

Guan, Mei-Li; Ma, De-Kun; Hu, Sheng-Wei; Chen, Yan-Jun; Huang, Shao-Ming

2010-12-20

90

Using VoIP to compete.  

Science.gov (United States)

Internet telephony, or VoIP, is rapidly replacing the conventional kind. This year, for the first time, U.S. companies bought more new Internet-phone connections than standard lines. The major driver behind this change is cost. But VoIP isn't just a new technology for making old-fashioned calls cheaper, says consultant Kevin Werbach. It is fundamentally changing how companies use voice communications. What makes VoIP so powerful is that it turns voice into digital data packets that can be stored, copied, combined with other data, and distributed to virtually any device that connects to the Internet. And it makes it simple to provide all the functionality of a corporate phone-call features, directories, security-to anyone anywhere there's broadband access. That fosters new kinds of businesses such as virtual call centers, where widely dispersed agents work at all hours from their homes. The most successful early adopters, says Werbach, will focus more on achieving business objectives than on saving money. They will also consider how to push VoIP capabilities out to the extended organization, making use of everyone as a resource. Deployment may be incremental, but companies should be thinking about where VoIP could take them. Executives should ask what they could do if, on demand, they could bring all their employees, customers, suppliers, and partners together in a virtual room, with shared access to every modern communications and computing channel. They should take a fresh look at their business processes to find points at which richer and more customizable communications could eliminate bottlenecks and enhance quality. The important dividing line won't be between those who deploy Vol P and those who don't, or even between early adopters and laggards. It will be between those who see Vol P as just a new way to do the same old things and those who use itto rethink their entire businesses. PMID:16171218

Werbach, Kevin

2005-09-01

91

P2-NaxVO2 system as electrodes for batteries and electron-correlated materials  

Science.gov (United States)

Layered oxides are the subject of intense studies either for their properties as electrode materials for high-energy batteries or for their original physical properties due to the strong electronic correlations resulting from their unique structure. Here we present the detailed phase diagram of the layered P2-NaxVO2 system determined from electrochemical intercalation/deintercalation in sodium batteries and in situ X-ray diffraction experiments. It shows that four main single-phase domains exist within the 0.5?x?0.9 range. During the sodium deintercalation (intercalation), they differ from one another in the sodium/vacancy ordering between the VO2 slabs, which leads to commensurable or incommensurable superstructures. The electrochemical curve reveals that three peculiar compositions exhibit special structures for x? = ?1/2, 5/8 and 2/3. The detailed structural characterization of the P2-Na1/2VO2 phase shows that the Na+ ions are perfectly ordered to minimize Na+/Na+ electrostatic repulsions. Within the VO2 layers, the vanadium ions form pseudo-trimers with very short V-V distances (two at 2.581?Å and one at 2.687?Å). This original distribution leads to a peculiar magnetic behaviour with a low magnetic susceptibility and an unexpected low Curie constant. This phase also presents a first-order structural transition above room temperature accompanied by magnetic and electronic transitions. This work opens up a new research domain in the field of strongly electron-correlated materials. From the electrochemical point of view this system may be at the origin of an entire material family optimized by cationic substitutions.

Guignard, Marie; Didier, Christophe; Darriet, Jacques; Bordet, Pierre; Elkaïm, Erik; Delmas, Claude

2013-01-01

92

Recuperación de la biomasa mediante la sucesión secundaria, Cordillera Central de los Andes, Colombia  

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Full Text Available En bosques secundarios premontanos tropicales es escasa la información sobre el tiempo requerido para recuperar la biomasa aérea y subterránea de los primarios. Por lo tanto, establecimos 33 parcelas de 0.1ha entre 550 y 1 700m en bosques secundarios que cubrían estadios serales de 3 a 36 años y estimamos la biomasa de las plantas y de las raíces gruesas con ecuaciones locales. Así como la biomasa de las pasturas y barbechos por cosecha de 54 y 18 parcelas, respectivamente. También se calculó la edad de las parcelas con informantes locales, sensores remotos, C14 y anillos de crecimiento. En cada parcela medimos la biomasa aérea viva por hectárea (Bav) y la de las raíces gruesas por hectárea (Brg). Modelamos la Bav y Brg en función de la edad mediante la ecuación de von Bertalanfy con asíntotas de 247t/ha (Bav) y 66t/ha (Brg) resultantes de la medición de 33 parcelas de 0.1ha en los bosques primarios. Con la razón Brg/Bav=f(t) estimamos 87 años para que los bosques secundarios recuperen la Bav existente en los primarios y 217 años para recuperar la Brg. La tasa máxima de crecimiento instantáneo de la Bav fue 6.95t/ha/año a los 10 años y la tasa media máxima de crecimiento 6.26t/ha/año a los 17 años. La media ponderada de la tasa de crecimiento absoluto de la Bav alcanzó 4.57t/ha/año y la relativa 10% anual. La razón Brg/Bav inicialmente aumenta muy aceleradamente hasta 4-5 años (25%), luego disminuye hasta 25 años (18%) para luego incrementar hasta 26.7Biomass recovery through secondary succession in the Cordillera Central de los Andes, Colombia. Estimations on biomass recovery rates by secondary tropical forests are needed to understand the complex tropical succession, and their importance on CO2 capture, to offset the warming of the planet. We conducted the study in the Porce River Canyon between 550 and 1 700m.a.s.l. covering tropical and premontane moist belts. We established 33 temporary plots of 50mx20m in secondary forests, including fallows to succesional forests, and ranging between 3 and 36 years old; we measured the diameter at breast height (D) of all woody plants with D?5cm. In each one of these plots we established five 10mx10m subplots, in which we measured the diameter betweem 1cm?D<5cm of all woody plants. We estimated the biomass of pastures by harvesting 54 plots of 2mx2m, and of shrubs in the fallows by harvesting the biomass in 18 plots of 5mx2m. We modeled Bav (above ground live biomass of woody plants) and Brg (coarse root biomass) as a function of succesional age (t) with the growth model of von Bertalanffy, using 247t/ha and 66t/ha as asymptote, respectively. Besides, we modeled the ratios brg/bav=f(D) and Brg/Bav=f(t). The model estimated that 87 years are required to recover the existing Bav of primary forests through secondary succession, and 217 years for the Brg of the primary forest. The maximum instantaneous growth rate of the Bav was 6.95 t/ha/yr at age 10. The maximum average growth rate of the Bav was 6.26 t/ha/yr at age 17. The weighted average of the absolute growth rate of the Bav reached 4.57t/ha/yr and the relative growth rate 10% annually. The ratio brg/bav decreases with increasing D. The ratio Brg/Bav initially increases very rapidly until age 5 (25%), then decreases to reach 25 years (18%) and increases afterwards until the ratio reaches the asymptote (26.7%). Rev. Biol. Trop. 59 (3):1337-1358. Epub 2011 September 01.

Jorge Ignacio del Valle; Héctor Iván Restrepo; Mónica María Londoño

2011-01-01

93

Slovenské parlamentné vo?by 2010: nacionálna agenda na ústupe?  

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Full Text Available The 2010 Slovak Parliamentary Elections: National Agenda on Retreat? In the Slovak parliamentary elections of 2010, the reformist centre-right parties defeated the left-nationalist coalition government led by Robert Fico. The election results brought some other surprises – the Movement for a Democratic Slovakia and its leader, three-times Prime Minister Vladimír Me?iar, as well as the Party of Hungarian Coalition were eliminated from the national parliament. Moreover, the election outcome of the radical right-wing Slovak National Party declined significantly. On the other hand, two new parties entered parliament. All in all, the election outcomes show the weakening of the nationalist agenda and the nationalist vote. The paper examines why this has happened and raises the question of to what extent it is sustainable.

Olga Gyarfášová

2011-01-01

94

CURRENT REFORMS IN EDUCATION IN SLOVAK ANDCZECH REPUBLIC / Sú?asné reformy vo vzdelávaní v Slovenskej a ?eskej republike  

Directory of Open Access Journals (Sweden)

Full Text Available The fee deal with current reforms in education in Slovak and Czech republic, their impact on quality of education, creation of educational standards and curriculum.Príspevok sa zaoberá sú?asnými reformami vo vzdelávaní v Slovenskej s ?eskej republike, ich vplyvom na kvalitu vzdelávania, tvorbu vzdelávacích štandardov a u?ebných plánov.

Šimková Zuzana

2009-01-01

95

Estimativa das contribuições dos sistemas anaeróbio lático e alático durante exercícios de cargas constantes em intensidades abaixo do VO2max/ Estimation of contributions of the anaerobic lactic and alactic systems during constant-load exercises at intensities below the VO2max  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O objetivo do estudo foi estimar as contribuições do metabolismo anaeróbio lático (MAL) e alático (MAA) em intensidades abaixo do consumo máximo de oxigênio (VO2max). Dez homens (23 ± 4 anos, 176,4 ± 6,8 cm, 72,4 ± 8,2 kg, 12,0 ± 4,5 % de gordura corporal) realizaram um teste progressivo até a exaustão voluntária para identificação do VO2max, da potência correspondente ao VO2max (WVO2max) e do segundo limiar ventilatório (LV2). Na segunda e na terceira v (more) isita foram realizados seis testes de cargas constantes (três testes por sessão) com intensidades abaixo do VO2max. Houve uma predominância do MAL sobre o MAA durante os exercícios submáximos a partir da intensidade correspondente ao LV2, sendo significativamente maior em 90% VO2max (p Abstract in english The purpose this study was that estimated contributions of the anaerobic lactic (MAL) and alactic (MAA) metabolism during constant load exercises at intensities below the maximal oxygen capacity uptake (VO2max). Ten males (23 ± 4 years, 176.4 ± 6.8 cm, 72.4 ± 8.2 kg, 12.0 ± 4.5 % of fat body) performed in the first visit a progressive test until exhaustion to identification of VO2max, power output corresponding to the VO2max (WVO2max) and second ventilatory threshold (more) (LV2). On the second and third visit, the participants performed six constant workload tests (3 per session) with intensities below VO2max. There was a predominance of MAL about MAA during the exercises sub-maximal from intensity corresponding to the LV2, being significantly higher at 90% VO2max (p

Silva-Cavalcante, Marcos David; Silva, Renata Gonçalves; Urso, Rodrigo Poles; Silva, Rogério Carvalho; Correia-Oliveira, Carlos Rafaell; Santos, Victor Gustavo Ferreira; Lima-Silva, Adriano Eduardo; Bertuzzi, Rômulo

2013-01-01

96

Catalytic oxidation of CO by N2O conducted via the neutral oxide cluster couple VO2/VO3.  

UK PubMed Central (United Kingdom)

Neutral vanadium and cobalt oxide clusters are generated at the same time employing a V-Co mixed target. Experimental results indicate that the reaction VO2 + N2O ? VO3 + N2 occurs in a fast flow reactor. This interpretation is further supported for a gas mixture of CO and N2O in the flow cell: regeneration of VO2 is observed for this case via the reaction VO3 + CO ? VO2 + CO2. A full catalytic cycle for the reaction N2O + CO ? N2 + CO2 is thus complete at room temperature enabled by the VO2/VO3 cluster couple. DFT calculations demonstrate that the entire catalytic process is overall barrierless and reproduce the experimental results quite well.

Wang ZC; Yin S; Bernstein ER

2013-07-01

97

Simulink based VoIP Analysis  

CERN Multimedia

Voice communication over internet not be possible without a reliable data network, this was first available when distributed network topologies were used in conjunction with data packets. Early network used single centre node network in which a single workstation (Server) is responsible for the communication. This posed problems as if there was a fault with the centre node, (workstation) nothing would work. This problem was solved by the distributed system in which reliability increases by spreading the load between many nodes. The idea of packet switching & distributed network were combined, this combination were increased reliability, speed & responsible for voice communication over internet, Voice-over-IP (VoIP)These data packets travel through a packet-switched network such as the Internet and arrive at their destination where they are decompressed using a compatible Codec (audio coder/decoder) and converted back to analogue audio. This paper deals with the Simulink architecture for VoIP network.

Singh, Hardeep; Mian, M

2010-01-01

98

Steganography of VoIP streams  

CERN Document Server

In this paper, we circumscribe available steganographic techniques that can be used for creating covert channels for VoIP (Voice over Internet Protocol) streams. Apart from characterizing existing steganographic methods we provide new insights by presenting two new techniques. First one is network steganography solution and exploits free/unused fields of the RTCP (Real-Time Control Protocol) and RTP (Real-Time Transport Protocol) protocols. The second method provides hybrid storage-timing covert channel by utilizing delayed audio packets. The results of the experiment, that was performed, regardless of steganalysis, to estimate a total amount of data that can be covertly transferred in VoIP RTP stream during the typical call, are also included in this article.

Mazurczyk, Wojciech

2008-01-01

99

Noble gas-transition-metal complexes: coordination of VO2 and VO4 by Ar and Xe atoms in solid noble gas matrixes.  

Science.gov (United States)

The matrix isolation infrared spectroscopic and quantum chemical calculation results indicate that vanadium oxides, VO2 and VO4, coordinate noble gas atoms in forming noble gas complexes. The results showed that VO2 coordinates two Ar or Xe atoms and that VO4 coordinates one Ar or Xe atom in solid noble gas matrixes. Hence, the VO2 and VO4 molecules trapped in solid noble gas matrixes should be regarded as the VO2(Ng)2 and VO4(Ng) (Ng = Ar or Xe) complexes. The total V-Ng binding energies were predicted to be 12.8, 18.2, 5.0, and 7.3 kcal/mol, respectively, for the VO2(Ar)2, VO2(Xe)2, VO4(Ar), and VO4(Xe) complexes at the CCSD(T)//B3LYP level of theory. PMID:16451016

Zhao, Yanying; Gong, Yu; Chen, Mohua; Zhou, Mingfei

2006-02-01

100

What are suspicious VoIP delays?  

CERN Document Server

Voice over IP (VoIP) is unquestionably the most popular real-time service in IP networks today. Recent studies have shown that it is also a suitable carrier for information hiding. Hidden communication may pose security concerns as it can lead to confidential information leakage. In VoIP, RTP (Real-time Transport Protocol) in particular, which provides the means for the successful transport of voice packets through IP networks, is suitable for steganographic purposes. It is characterised by a high packet rate compared to other protocols used in IP telephony, resulting in a potentially high steganographic bandwidth. The modification of an RTP packet stream provides many opportunities for hidden communication as the packets may be delayed, reordered or intentionally lost. In this paper, to enable the detection of steganographic exchanges in VoIP, we examined real RTP traffic traces to answer the questions, what do the "normal" delays in RTP packet streams look like? and, is it possible to detect the use of know...

Mazurczyk, Wojciech; Szczypiorski, Krzysztof

2010-01-01

 
 
 
 
101

Comparative study of correlation effects in CaVO3 and SrVO3  

CERN Multimedia

We present parameter-free LDA+DMFT (local density approximation + dynamical mean field theory) results for the many-body spectra of cubic SrVO3 and orthorhombic CaVO3. Both systems are found to be strongly correlated metals, but not on the verge of a metal-insulator transition. In spite of the considerably smaller V-O-V bond angle in CaVO3 the LDA+DMFT spectra of the two systems for energies EE_F shows more pronounced, albeit still small, differences. This is in contrast to earlier theoretical and experimental conclusions, but in good agreement with recent bulk-sensitive photoemission and x-ray absorption experiments.

Nekrasov, I A; Kondakov, D E; Kozhevnikov, A V; Pruschke, T; Held, K; Vollhardt, D; Anisimov, V I; Pruschke, Th.

2005-01-01

102

Flujos de biomasa y estructura de un ecosistema de surgencia tropical en La Guajira, Caribe colombiano  

Directory of Open Access Journals (Sweden)

Full Text Available La Guajira es un ecosistema de surgencia explotado en la costa del Caribe colombiano. Con el propósito de integrar la información disponible sobre el sistema se construyó un modelo trófico de 27 grupos funcionales usando el programa Ecopath 5.0 Beta. Se obtuvo una base cuantitativa para compararlo con otros sistemas de surgencia. La Guajira presenta una biomasa total de 68 t/km²/año, la producción primaria neta del sistema es de 1 248.51 t/km²/año y las transferencias totales del sistema son de 3 275 t/km²/año, lo que indica un ecosistema con una surgencia moderada comparada con otros sitios. Las mayores transferencias de energía se dan del nivel trófico I-II (68.93 %), aunque existe una importante proporción de flujos al detritus (32 %). Los resultados en los atributos de madurez del sistema sugieren que La Guajira es un ecosistema inmaduro debido a que la relación P/R excede a 1 y está en desarrollo debido a la baja ascendencia (33.7 %) y alta capacidad de desarrollo (66.3 %) como ocurre con otras surgencias donde se presentan valores de ascendencia entre 20 % y 35 %. Aunque los datos básicos de entrada en el modelo fueron buenos, gracias a las investigaciones que se han elaborado entre 1995 y 2000, existen algunos grupos donde no se encuentra aún información adecuada; especialmente en los valores de biomasa del fitoplancton, invertebrados, bagres, peces depredadores pelágicos, así como estimaciones de producción en invertebrados, peces depredadores pelágicos y peces pequeños pelágicos. No existe una cuantificación de las poblaciones de mamíferos y aves en el área de estudio, los cuales constituyen depredadores superiores y hacen parte esencial en sistemas de surgenciaBiomass flow and structure of a tropical upwelling ecosystem in La Guajira, Colombian Caribbean. La Guajira is an exploited tropical upwelling ecosystem in the Colombian Caribbean coast. A trophic model of 27 functional groups was constructed using the ECOPATH 5.0 Beta software to integrate the available information on the ecosystem. The model allowed a comparison with other trophic flow models of upwelling ecosystems. Total system biomass (68 t/km²/year), net system production (1248.5 t/km²/year), and total system throughput (3 275 t/km²/year) make La Guajira moderate when compared with other systems. The largest amount of energy throughput is achieved from trophic level I to II (68.93 %), although an important proportion of the total flow originates from detritus (32 %). The production/respiration ratio exceeds 1, suggesting that La Guajira is an immature ecosystem and is in development, as determined by its low ascendency (33.7 %) and high development capacity (66.3 %), similar to other upwellings that have values of ascendency between 20 % and 35 %. Although the basic input data were good and covered 1995 to 2000, appropriate information is still not available on some trophic groups such as biomass (for phytoplankton, invertebrates, catfishes and pelagic predator fishes), secondary production data (invertebrates, pelagic predator fishes, and small pelagic fishes), and seabird and mammal populations, which are top trophic levels and an essential part of upwelling ecosystems. Rev. Biol. Trop. 54 (4): 1257-1282. Epub 2006 Dec. 15

Maria Isabel Criales-Hernández; Camilo B. García; Matthias Wolff

2006-01-01

103

USO DE LA LEVADURA TORULA (TORULOPSIS UTILIS) EN LA OBTENCIÓN DE BIOMASA DE ARTEMIA  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Se llevaron a cabo estudios para determinar la factibiíidad del uso de la levadura torula (Torulopsis utilis), como fuente de alimento en cultivos intensivos de Artemia. Se alcanzaron rendimientos máximos de biomasa de 5.14 g/l y 8.43 mm de largo medio total en la variante de mejores resultados. Concentraciones de levadura de 1 g/l/día en el período inicial de 6 días pueden considerarse adecuadas para el crecimiento de la Artemia, mientras que concentraciones de 3.5 (more) y 7 g/l/día son excesivas. A partir del séptimo día 3 g/l/día constituye una concentración apropiada de alimento mientras que 1 g/l/día es insuficiente para obtener un crecimiento satisfactorio en esta etapa. Las ecuaciones de crecimiento para este cultivo en las condiciones descritas son las siguientes: variante de 1 g/l/día, L = -0.5214 + 0.4837 T; variante de 3 g/l/día, L = -1.1707 + 0.738 T. Abstract in english Studies were carried out to determine the possibilities of use torula yeast (Torulopsis utilis), as a source of feed in intensive cultured Artemia, Maximum biomass yields of 5.14 g/l and 8.43 mm of average total length were obtained for the treatment with the best results. Yeast concentration of 1 g/l/day in the initial 6 days period, can be considered adequate for Artemia growth while the concentration of 1 g/l/day is insufficient to obtain a satisfactory growth. The gro (more) wth equations in the described culture conditions were as follow: treatment 1 g/l/day, L= -0.5214 + 0.4837 T; treatment 3 g/l/day, L = -1.1707 + 0.738 T.

Tizol Correa, Rafael

1994-12-01

104

Fractal Analysis and Modeling of VoIP Traffic  

UK PubMed Central (United Kingdom)

In this paper a fractal analysis study of VoIP traffic ispresented. The characteristics of measured VoIP trafficon both call and packet level have been investigated.The results support the popular Poisson process for VoIPcall arrival modeling but we argue that the call holdingtimes follow heavy-tailed distributions rather than exponentialdistributions. We propose the generalized Paretodistribution for modeling the call holding times. At thepacket level we have found that the exponential modelingof On and Off periods is also inappropriate andheavy-tailed characteristics have been identified in caseof all the investigated VoIP codecs. The generalizedPareto distribution can be used as an accurate model forthe On and Off periods too. In the analysis we revealedthat the aggregated VoIP traffic has fractal characteristicsand we suggest the fractional Gaussian noise modelfor the aggregated VoIP traffic.

Trang Dinh Dang; Balzs Sonkoly; Sndor Molnr

105

Influencia de la aplicación de vinaza en actividad y biomasa microbiana en un Entic Dystropept y un Fluventic haplustoll del Valle del Cauca, Colombia  

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Full Text Available Con la aplicación de vinaza, residuo de la producción de alcohol carburante a partir de la caña de azúcar, se evaluó el efecto sobre la actividad y biomasa microbiana del suelo y el suministro de K+ al cultivo de maíz dulce (Zea Mays) en un Entic Dystropept y un Fluventic Haplustoll del Valle del Cauca, Colombia. Se utilizó un diseño completamente al azar con cuatro tratamientos y cinco repeticiones: T1 (100% requerimiento de K+ con KCl), T2 (100% requerimiento de K+ con vinaza), T3 (50% requerimiento de K+ con KCl +50% con vinaza) y T4 (25% requerimiento de K+ con KCl +75% con vinaza). Se estimó biomasa microbiana por el método de fumigación-extracción. Se realizó análisis de varianza, prueba de comparación de medias, regresiones y correlaciones (SAS). Se presentaron diferencias significativas en la actividad y biomasa microbiana por época de muestreo y entre los diferentes muestreos; al final del cultivo el Entic Dystropept presentó el contenido más alto de biomasa microbiana-C en el T2, mientras que en el Fluventic Haplustoll fue en el T1. El menor qCO2 fue para el T2 del Entic Distropept y T1 del Fluventic Haplustoll, estos tratamientos presentaron mayor acumulación de biomasa en cada suelo respectivamente T2 (30 450 kg ha-1) y T1 (21 015.6 kg ha-1).

Montenegro Gómez Sandra Patricia; Menjivar Flórez Juan Carlos; Bonilla Correa Carmen Rosa; Madriñán Molina Raúl

2009-01-01

106

Intrusion detection mechanisms for VoIP applications  

CERN Multimedia

VoIP applications are emerging today as an important component in business and communication industry. In this paper, we address the intrusion detection and prevention in VoIP networks and describe how a conceptual solution based on the Bayes inference approach can be used to reinforce the existent security mechanisms. Our approach is based on network monitoring and analyzing of the VoIP-specific traffic. We give a detailed example on attack detection using the SIP signaling protocol.

Nassar, M E B; Festor, O; Nassar, Mohamed El Baker; State, Radu; Festor, Olivier

2006-01-01

107

Voice-over-Internet protocol (VoIP) Curriculum Module  

Science.gov (United States)

This curriculum module, created by Dr. Mona Cherri at North Lake College and published by the Convergence Technology Center, presents this module of information about Voice-over-Internet protocol (VoIP) for telecommunications technology and information systems courses. Here, Dr. Cherri has broken the material into five parts: Background Information, VoIP versus public switched telephone networks (PSTNs), VoIP Applications and Services, References, and Useful URLs.

Cherri, Mona

2008-10-27

108

EVALUACIÓN DE LA BIOMASA Y MANEJO DE Lemna gibba (LENTEJA DE AGUA) EN LA BAHÍA INTERIOR DEL LAGO TITICACA, PUNO  

Directory of Open Access Journals (Sweden)

Full Text Available Uno de los mayores problemas que enfrenta la ciudad de Puno es la presencia de la lenteja de agua (Lemna gibba) en la bahía interior del Lago Titicaca, debido al proceso de eutrofización que sufre a causa del mal tratamiento de las aguas residuales de la ciudad de Puno. Muchas de las estrategias planteadas hasta ahora no han dado resultados positivos en la reducción de la biomasa de Lemna gibba, debido a que estos planes están direccionados a la exterminación de este organismo. En lugar de ello se debe pensar en la forma más sostenible de hacer uso de la lenteja. Es por eso que los objetivos fueron: (a) estimar la biomasa (kg/m²) de lenteja de agua de la bahía interior del lago Titicaca y, (b) plantear una estrategia de manejo de la lenteja de agua de la bahía interior del lago Titicaca. El promedio de la biomasa de la lenteja de agua en la bahía interior fue de 6.94 kg/m², mientras que los promedios de pH y temperatura del agua fueron de 6.3 y 13.8°C, respectivamente. Esto prueba la eficacia de este organismo para crecer en condiciones difíciles (además hay altos niveles de N, P y metales pesados), por lo que su manejo puede ser una alternativa para disminuir el proceso de eutrofización del lago. Las estrategias de manejo de lenteja estuvieron enmarcadas dentro de un plano social, económico y ambiental, lo que permite su sostenibilidad en beneficio de la población de Puno y del ecosistema del lago Titicaca.

Ángel Canales-Gutiérrez

2010-01-01

109

COMPETENCIA POR SUSTRATO DURANTE EL DESARROLLO DE BIOMASA SULFATORREDUCTORA A PARTIR DE UN LODO METANOGÉNICO EN UN REACTOR UASB  

Directory of Open Access Journals (Sweden)

Full Text Available En este trabajo se estudió la competencia entre microorganismos metanogénicos y sulfatorreductores utilizando un reactor anaerobio de lecho de lodo granular con flujo ascendente (UASB) a escala laboratorio, el cual fue usado para el enriquecimiento de biomasa sulfatorreductora a partir de un lodo granular de origen metanogénico. El reactor se alimentó con una mezcla de etanol y acetato, la carga orgánica se incrementó de 0.5 a 2 g de demanda química de oxígeno (DQO)/L-d a pH de 7.0. El consumo de DQO fue mayor a 90 % y la alcalinidad producida por la oxidación del sustrato incrementó el pH en el efluente hasta 8.0. A partir de los 50 días de operación, el reactor se alimentó con lactato y sulfato para promover la sulfatorreducción. La carga orgánica se aumentó de 1 a 3 g DQO/L-d con una relación DQO/Sulfato de 0.67 a un tiempo de retención hidráulico de un día. A los 194 días de operación del reactor el máximo consumo de DQO y sulfato obtenido fue de 94 y 22 %, respectivamente. La concentración total del sulfuro alcanzada fue de 310 mg S2-/L y la actividad sulfatorreductora de la biomasa fue de 0.29 g DQO-H2S/g SSV-d, lo que mostró el desarrollo de biomasa sulfatorreductora. La actividad metanogénica que se obtuvo fue de 0.35 g DQO-CH4/g SSV-d, estos resultados mostraron que los organismos metanogénicos no fueron desplazados por las bacterias sulfatorreductoras, coexistiendo ambos tipos de microorganismos en el lodo granular anaerobio al final de la operación del reactor.

Marisol GALLEGOS-GARCÍA; Lourdes B. CELIS; Elías RAZO-FLORES

2010-01-01

110

Security Research on VoIP with Watermarking  

Science.gov (United States)

With the wide application of VoIP, many problems have occurred. One of the problems is security. The problems with securing VoIP systems, insufficient standardization and lack of security mechanisms emerged the need for new approaches and solutions. In this paper, we propose a new security architecture for VoIP which is based on digital watermarking which is a new, flexible and powerful technology that is increasingly gaining more and more attentions. Besides known applications e.g. to solve copyright protection problems, we propose to use digital watermarking to secure not only transmitted audio but also signaling protocol that VoIP is based on.

Hu, Dong; Lee, Ping

2008-11-01

111

Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx) em jogadores de futebol profissional Effect of time intervals of ventilatory sampling in the variability of maximum oxygen uptake in professional soccer players  

Directory of Open Access Journals (Sweden)

Full Text Available O propósito deste estudo foi verificar, em futebolistas profissionais, o impacto de sete intervalos de tempo sobre a variável fisiológica consumo máximo de oxigênio (VO2 máx). Dezoito jogadores de futebol com média de idade de 24 ± 4 anos (18-31), peso de 72,5 ± 5,9kg (62-83) e estatura de 176,5 ± 7,0cm (164-188) foram submetidos a teste ergométrico máximo em esteira rolante, utilizando-se protocolo escalonado contínuo. A resposta de freqüência cardíaca (FC) foi registrada por meio de um eletrocardiógrafo computadorizado de 12 derivações simultâneas. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram calculadas a partir de valores medidos por um sistema espirométrico computadorizado. Os resultados deste estudo demonstraram que houve variabilidade significante do VO2 máx (p The purpose of this investigation was to verify the impact of seven ventilatory time intervals on the maximum oxygen uptake (VO2 max) in professional soccer players. Eighteen male soccer players aged 24.4 ± 4 (18-31), weight 72.5 ± 5.9 kg (62-83) and height 176.5 ± 7 cm (164-188) were submitted to a maximum exercise test on treadmill, using the continuous protocol. The heart rate response was recorded by means of computerized ECG with 12 leads, simultaneously. The respiratory exchange ratio, carbon dioxide production, oxygen uptake and pulmonary ventilation were calculated by means of the spirometric computerized system. The results of this study demonstrated that there was significant variability (p < 0.05) in VO2 max only when it was compared instantaneously and by breath-by-breath response, in relation to other intervals analyzed (10, 20, 30, 40, 50 and 60 seconds, respectively). In conclusion, the authors observed that VO2 max increases were proportional to those found in the ventilatory sample intervals during the progressive intensity exercise. However, the higher time interval underestimated its increase. Thus, the authors suggest that the investigator should utilize mean intervals in a range between 10 and 60 seconds, since no significant statistic difference was verified among these intervals.

Paulo Roberto Santos Silva; Angela Romano; Ana Maria Visconti; Alberto Alves de Azevedo Teixeira; Carla Dal Maso Nunes Roxo; Gilberto da Silva Machado; Luciana Collet Winther Rebello; Jorge Mendes de Sousa

1999-01-01

112

Polarization dependence of phonon and electronic Raman intensities in PrVO4 and NdVO4  

International Nuclear Information System (INIS)

[en] The polarization behavior of the phonon and electronic Raman intensities in PrVO4 and NdVO4 has been measured. These experimental intensities are compared with the intensities predicted by a polarization-dependent intensity theory. Good agreement was found between theory and experiment. The fitted values of the ratio F1/F2 for PrVO4 and NdVO4 were found to be 1.0 and 0.48, respectively. The relative values of the ?qt parameters obtained from the fit were compared with theoretical values which were derived using both second- and third-order theory, where the latter included the spin-orbit interaction. Axe close-quote s second-order theory was found to adequately explain the relative intensities of electronic Raman transitions in PrVO4 and NdVO4. copyright 1997 The American Physical Society

113

Utilización del medio de cultivo UIT-A en la obtención de biomasa para la identificación bioquímica micobacteriana  

Directory of Open Access Journals (Sweden)

Full Text Available Se compara el medio de cultivo sólido UIT-A con el Lowenstein Jensen, para la obtención de biomasa en el montaje del test bioquímico de identificación de micobacterias "no tuberculosas" (MNT), con el objetivo de valorar la posibilidad de utilización como medio de cultivo para el montaje y análisis de dichas pruebas bioquímicas. Los resultados obtenidos en los 2 medios de cultivo utilizados fueron iguales, por lo que se recomienda el uso del medio de cultivo UIT-A fundamentalmente para aquellas cepas con crecimiento pobre o escaso.

LILIAN M. MEDEROS CUERVO; CARIDAD FERRA SALAZAR; JOSE A. VALDIVIA

1995-01-01

114

GASIFICACIÓN DE BIOMASA PARA PRODUCCIÓN DE COMBUSTIBLES DE BAJO PODER CALORÍFICO Y SU UTILIZACIÓN EN GENERACIÓN DE POTENCIA Y CALOR  

Directory of Open Access Journals (Sweden)

Full Text Available Gases combustibles con bajo poder calorífico (LCV) generados durante la gasificación de biomasa se prevén como combustibles alternativos para diferentes aplicaciones como son calderas, motores de combustión interna, quemadores y turbinas de gas [1]. Esta fuente alternativa de energía presenta varias dificultades en su utilización; entre otras, la necesidad de la adecuación de un sistema eficiente de filtrado y la adaptación de los sistemas de combustión para recibir un flujo de combustible más elevado con propósito de generar el mismo calor[7].

CARLOS AUGUSTO ESTRADA; ALBERTO ZAPATA MENESES

2004-01-01

115

The NESPOLE! VoIP Dialogue Database  

UK PubMed Central (United Kingdom)

This paper presents the status of the NESPOLE! datacollection as of end of February, 2001. A multilingual VoIP(Voice over Internet Protocol networks) database consistingof 200 dialogues in 4 languages (English, German, Italian andFrench) was recorded and transcribed. Dialogue speakerswere connected via a H323 video-conferencing terminal. Wedescribe the task, the technical architecture, the recordingprocedure and the transcription process of the NESPOLE!data collection. We provide some statistics concerning thedata and, finally, we address problems that arose during thecollection and annotation process.1.

Susanne Burger; Laurent Besacier; Paolo Coletti; Florian Metze; Cline Morel

116

The NESPOLE! VoIP Dialogue Database  

UK PubMed Central (United Kingdom)

This paper presents the status of the NESPOLE! datacollection as of end of February, 2001. A multilingual VoIP(Voice over Internet Protocol networks) database consistingof 200 dialogues in 4 languages (English, German, Italian andFrench) was recorded and transcribed. Dialogue speakerswere connected via a H323 video-conferencing terminal. Wedescribe the task, the technical architecture, the recordingprocedure and the transcription process of the NESPOLE!data collection. We provide some statistics concerning thedata and, finally, we address problems that arose during thecollection and annotation process.

Susanne Burger; Laurent Besacier; Paolo Coletti; Florian Metze; Cline Morel

117

Risk analysis on VoIP systems Áhættugreining fyrir VoIP  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The goal of this thesis was to perform a risk analysis on a VoIP system for service providers. Main threats of the system were analysed and subsequently each threat was briefly introduced. Assets of the system were analysed, for the risk analysis, and probability of threat and impact of threat estim...

Knútur Birgir Otterstedt 1984

118

Componente lento do VO2 em crianças durante exercício pesado de corrida: análise com base em diferentes modelos matemáticos Componente lento de VO2 en niños durante ejercicio arduo de carrera: análisis con base en diferentes modelos matemáticos Slow component of VO2 in children during running exercise performed at heavy intensity domain: analysis with different mathematical models  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste estudo foi verificar e quantificar a magnitude do componente lento do consumo de oxigênio (CL) em crianças submetidas a exercícios de corrida em esteira rolante, com cargas constantes de intensidade acima do limiar de lactato (75%D), utilizando para isso dois modelos de análise: a) modelo matemático com três termos exponenciais; e b) modelo deltaVO2 6-3min. Participaram do estudo oito crianças do sexo masculino (11,92 ± 0,63 anos; 44,06 ± 13,01kg; 146,63 ± 7,25cm; e níveis de maturação sexual 1 e 2), aparentemente saudáveis, não treinadas, que realizaram em diferentes dias: 1) teste incremental na esteira rolante para a determinação do consumo de oxigênio de pico (VO2pico) e do limiar de lactato (LL); e 2) dois testes de carga constante em esteira rolante durante seis minutos na intensidade de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL)]. Para determinação do CL utilizaram-se: a) modelo matemático de três termos (Exp3); e b) a diferença no VO2 entre o sexto e o terceiro minuto de exercício (deltaVO2 6-3min). O CL foi expresso em valores absolutos (ml/min) e também como a contribuição percentual do CL para o aumento do VO2 no final do exercício (%CL). O CL determinado pelo modelo Exp3 (129,69 ± 75,71ml/min e 8,4 ± 2,92%) foi significantemente maior do que o obtido pelo modelo deltaVO2 6-3min (68,69 ± 102,54ml/min e 3,6 ± 7,34%). Portanto, os valores de CL obtidos em crianças durante o exercício de corrida realizado no domínio pesado (75%delta) são dependentes do modelo de análise (Exp3 x deltaVO2 6-3min).El objetivo de este estudio ha sido el de verificar y cuantificar la magnitud del componente lento del consumo de oxígeno (CL) en niños, sometidos a ejercicios de carrera en cinta rodante, con cargas constantes de intensidad por encima del límite de lactato (75%delta), utilizando para esto dos modelos de análisis: a) modelo matemático con tres términos exponenciales; y b) modelo deltaVO2 6-3 min. Participaron del estudio 8 niños del sexo masculino (11,92 ± 0,63 años; 44,06 ± 13,01 kg; 146,63 ± 7,25 cm; y niveles de madurez sexual 1 y 2), aparentemente saludables, no entrenados, que realizaron en diferentes días: 1) Test incremental en la cinta rodante para determinar el consumo de oxígeno de pico (VO2pico) y del límite de lactato (LL); y 2) Dos tests de carga constante en cinta rodante durante seis minutos a intensidad de 75%delta [75%delta = LL + 0,75 x (VO2pico - LL)]. Para determinar el CL usamos: a) modelo matemático de tres términos (Exp3); y b) la diferencia en el VO2 entre el sexto y el tercer minuto de ejercicio (deltaVO2 6-3 min). El CL fue expresado en valores absolutos (ml/min) y también como contribución porcentual de CL para el aumento de VO2 al final del ejercicio (%CL). El CL determinado por el modelo Exp3 (129,69 ± 75,71 ml/min y 8,4 ± 2,92%) fue significativamente mayor al que fue obtenido por el modelo deltaVO2 6-3 min (68,69 ± 102,54 ml/min y 3,6 ± 7,34%). Por tanto, los valores de CL obtenidos en niños durante el ejercicio de carrera realizado en dominio pesado (75%delta) son dependientes del modelo de análisis (Exp3 x deltaVO2 6-3 min).The purpose of this study was to identify and quantify the magnitude of the slow component of VO2 (SC) in children during running exercise, performed at heavy intensity domain (75%delta), using two different mathematical models: a) three-exponential model and; b) deltaVO2 6-3 min. Eight healthy male children (11.92 ± 0.63 years; 44.06 ± 13.01 kg; 146.63 ± 7.25 cm; and sexual maturity levels 1 and 2), not trained, performed in different days the following tests: 1) incremental running treadmill test to determine the peak oxygen uptake (VO2peak) and the lactate threshold (LT); and 2) two transitions from baseline to 75%delta [75%D = LT + 0.75 x (VO2 peak - LT)] for six minutes on treadmill. The SC was deter mined by two models: a) three-exponential model (Exp3); and b) the VO2 difference between the sixth and the third exercise minute (deltaVO2 6-3min). The SC was expr

Fabiana Andrade Machado; Luiz Guilherme Antonacci Guglielmo; Camila Coelho Greco; Benedito Sérgio Denadai

2006-01-01

119

Cambios en el porcentaje de sodio intercambiable (PSI) y la relación de absorción de sodio (RAS) de un suelo y su influencia en la actividad y biomasa microbiana  

Directory of Open Access Journals (Sweden)

Full Text Available Con el objetivo de evaluar los cambios en el PSI, la RAS y su influencia en la actividad y  biomasa  microbiana  del suelo,  se aplicaron  diversas  concentraciones  de vinaza  como enmienda procedente de la industria de alcohol carburante, sobre un suelo afectado por sodicidad con severas limitaciones en las condiciones físicas, químicas y biológicas. Se aplicó un diseño en bloques completos al azar que incluye cuatro tratamientos y tres repeticiones, y muestreos de suelo al inicio y final del proceso a tres profundidades (0-20, 20-40 y 40-60 cm), cuyas variables de respuesta a medir fueron  la respiración, C- biomasa microbiana, MO%, pH, CIC, CE, RAS y PSI. La actividad biológica (CO2) y el C-biomasa microbiana mostraron incrementos significativos en el rango ideal para el establecimento del cultivo de caña.

Gasca Cesar A.; Menjivar Juan Carlos; Torrente Trujillo Armando

2011-01-01

120

Efeito do tempo de intervalo da amostra ventilatória na variabilidade do consumo máximo de oxigênio (VO2 máx) em jogadores de futebol profissional/ Effect of time intervals of ventilatory sampling in the variability of maximum oxygen uptake in professional soccer players  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O propósito deste estudo foi verificar, em futebolistas profissionais, o impacto de sete intervalos de tempo sobre a variável fisiológica consumo máximo de oxigênio (VO2 máx). Dezoito jogadores de futebol com média de idade de 24 ± 4 anos (18-31), peso de 72,5 ± 5,9kg (62-83) e estatura de 176,5 ± 7,0cm (164-188) foram submetidos a teste ergométrico máximo em esteira rolante, utilizando-se protocolo escalonado contínuo. A resposta de freqüência cardíaca (F (more) C) foi registrada por meio de um eletrocardiógrafo computadorizado de 12 derivações simultâneas. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram calculadas a partir de valores medidos por um sistema espirométrico computadorizado. Os resultados deste estudo demonstraram que houve variabilidade significante do VO2 máx (p Abstract in english The purpose of this investigation was to verify the impact of seven ventilatory time intervals on the maximum oxygen uptake (VO2 max) in professional soccer players. Eighteen male soccer players aged 24.4 ± 4 (18-31), weight 72.5 ± 5.9 kg (62-83) and height 176.5 ± 7 cm (164-188) were submitted to a maximum exercise test on treadmill, using the continuous protocol. The heart rate response was recorded by means of computerized ECG with 12 leads, simultaneously. The resp (more) iratory exchange ratio, carbon dioxide production, oxygen uptake and pulmonary ventilation were calculated by means of the spirometric computerized system. The results of this study demonstrated that there was significant variability (p

Silva, Paulo Roberto Santos; Romano, Angela; Visconti, Ana Maria; Teixeira, Alberto Alves de Azevedo; Roxo, Carla Dal Maso Nunes; Machado, Gilberto da Silva; Rebello, Luciana Collet Winther; Sousa, Jorge Mendes de

1999-04-01

 
 
 
 
121

VO2 kinetics during heavy and severe exercise in swimming.  

UK PubMed Central (United Kingdom)

The purpose of this study was to describe the VO2 kinetics above and below respiratory compensation point (RCP) during swimming. After determination of the gas-exchange threshold (GET), RCP and VO(2max), 9 well-trained swimmers (21.0 ± 7.1 year, VO(2max)=57.9 ± 5.1 ml.kg (- 1).min (- 1)), completed a series of "square-wave" swimming transitions to a speed corresponding to 2.5% below (S - 2.5%) and 2.5% above (S+2.5%) the speed observed at RCP for the determination of pulmonary VO2 kinetics. The trial below (~2.7%) and above RCP (~2%) was performed at 1.28 ± 0.05 m.s (- 1) (76.5 ± 6.3% VO(2max)) and 1.34 0.05 m.s (- 1) (91.3 ± 4.0% VO(2max)), respectively. The time constant of the primary component was not different between the trials below (17.8 ± 5.9 s) and above RCP (16.5 ± 5.1 s). The amplitude of the VO(2)slow component was similar between the exercise intensities performed around RCP (S - 2.5%=329.2 ± 152.6 ml.min (- 1) vs. S+2.5%=313.7 ± 285.2 ml.min (- 1)), but VO(2max) was attained only during trial performed above RCP (S-2.5%=91.4 ± 5.9% VO(2max) vs. S+2.5%=103.0 ± 8.2% VO(2max)). Thus, similar to the critical power during cycling exercise, the RCP appears to represent a physiological boundary that dictates whether VO(2) kinetics is characteristic of heavy- or severe-intensity exercise during swimming.

Pessoa Filho DM; Alves FB; Reis JF; Greco CC; Denadai BS

2012-09-01

122

Determinación de las reservas de carbono de la biomasa aérea, en diferentes sistemas de uso de la tierra en San Martín, Perú  

Directory of Open Access Journals (Sweden)

Full Text Available Se determinó la biomasa aérea en diferentes sistemas de uso de la tierra en la región de San Martín-Perú, con la finalidad de conocer el potencial de captura de carbono. Los sistemas de uso de la tierra evaluados fueron: Bosque primario, Bosque secundario de diferentes edades, sistemas agrícolas locales maíz (Zea maiz), arroz (Oriza Sativa), pastos (Brachiaria) y sistemas agroforestales con café (Coffea arabica) bajo sombra y cacao (Cacao sp.). También se comparó este potencial con otros sistemas de uso de la tierra de otras regiones del Perú y se monitoreó la pérdida de reservas de carbono después del corte de la foresta y su reemplazo por cultivos. En cada uno de éstos sistemas se establecieron al azar cinco transectos donde se evaluó la biomasa arbórea. Dentro de éstos transectos se establecieron cuadrados también al azar para cuantificar la biomasa herbácea y la biomasa de hojarasca. El carbono total en el bosque primario fue de 485 tm C ha-1, superando ampliamente las reservas del bosque secundario de 50 años y de bosque descremado de 20 años. Con relación al bosque primario se observa una reducción de reservas en más de 50% del bosque secundario de 50 años (234 tm C ha-1). El bosque descremado de 20 años perdió más del 80% de reservas (62 tm C ha-1). El nivel de reservas de carbono en la biomasa de hojarasca de los sistemas boscosos, no es significativo al compararlo con el total de las reservas de carbono de la biomasa aérea; sin embargo si es significativo para sistemas agroforestales. Los sistemas agroforestales secuestraron entre 19 a 47 tm C ha-1, dependiendo de la cantidad de especies forestales, tipo de cultivo, edad y tipo de suelo y recuperan el potencial de captura en forma productiva. Los sistemas agrícolas capturaron poco C (5 tm C ha-1), además generan fugas de gases efecto invernadero (GEI) cuando se usan agroquímicos y quema de rastrojos, entre otros.

Tatiana Lapeyre; Julio Alegre; Luis Arévalo

2004-01-01

123

Crystal chemistry of LiVO2  

International Nuclear Information System (INIS)

[en] Large single crystal plates of Li1-xVO2 (x ? 0.2) have been first grown using the Li2O-B2O3 flux method. Precession photographs reveal that an additional superstructure is formed on the basic ordered rock salt (ORS) structure at room temperature, and is released above transition temperature forming the ideal ORS structure. Small amount of LiV2O4 decomposed partially from the Li1-xVO2 crystals on heating above Tc is also confirmed. Average structure analysis based on the ORS structure reveals that there exists large anisotropy on the thermal ellipsoid of V-site. The results of X-ray diffraction and the EX-AFS analysis at room temperature indicate that the superstructure is originated in formation of the V3-trimers, and the displacement of V ions is estimated to be 0.16 A. Three kinds of stacking sequence of V3-trimers are proposed to explain the intensity distributions of superstructure reflections. Temperature dependence of electrical resistivity and magnetic susceptibility are measured. Significant anisotropy in both of them is observed, indicating two-dimensional feature of this compound. (author)

1996-01-01

124

A facile route to VN and V{sub 2}O{sub 3} nanocrystals from single precursor NH{sub 4}VO{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

V{sub 2}O{sub 3} and VN nanocrystals have been synthesized by the decomposition of the precursor NH{sub 4}VO{sub 3} and following nitridation in an autoclave with metallic Na flux at 450-600 deg. C. X-ray powder diffraction (XRD) recorded the evolution process of the reaction from precursor NH{sub 4}VO{sub 3} to hexagonal V{sub 2}O{sub 3} and then to NaCl-type VN. In addition, the products were characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM)

Yang Zeheng [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); School of Chemical Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Cai Peijun [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Chen Luyang [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gu Yunle [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi Liang [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhao Aiwu [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Qian Yitai [Structure Research Laboratory and Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)]. E-mail: zehengy@mail.ustc.edu.cn

2006-08-31

125

VoIP makes voice heard--functionality is up.  

UK PubMed Central (United Kingdom)

Phil Wade, sales and marketing director, and Mathew Wakelam, VoIP product manager, at alarm and communication specialist Static Systems Group, discuss wireless VoLP's potential in healthcare establishments and examine how, in particular, the technology can be successfully integrated with nurse call systems.

Wade P; Wakelam M

2008-05-01

126

Leg strength and the VO2 max of older men.  

UK PubMed Central (United Kingdom)

The purpose of the study was to determine if leg strength limits VO2 max and the ability to reach a plateau during VO2 max test in older men during cycle ergometry. Men aged 70-80 years were randomly selected into a strength training (ST, n=12) 3 times weekly for 16 weeks, followed by 4 weeks detraining or a non-training control group (C, n=12). Leg strength and VO2 max were assessed every 4 weeks for 20 weeks; body composition and cardiac function were assessed before and after 16 weeks training and after 4 weeks detraining. Leg strength, upper leg muscle mass (ULMM), arterial-venous O2 difference (a-v O2 difference) and VO2 max increased in the ST group (95±0.6%, 7±0.7%. 6.2±0.5% and 8±0.8%, respectively; P<0.05) after 16 weeks training. After 4 weeks detraining, gains in ULMM (50%) and strength (75%) were retained, but VO2 max and a-v O2 difference returned to pre-training levels. There was no change in the ability of the participants to reach a plateau during VO2 max testing over the 20-week study. These findings indicate that leg strength may not limit either VO2 max or the ability to plateau during VO2 max tests in older men during cycle ergometry.

Lovell D; Cuneo R; Delphinus E; Gass G

2011-04-01

127

Assessing the security of VoIP Services  

Digital Repository Infrastructure Vision for European Research (DRIVER)

VoIP networks are in a major deployment phase and are becoming widely spread out due to their extended functionality and cost efficiency. Meanwhile, as VoIP traffic is transported over the Internet, it is the target of a range of attacks that can jeopardize its proper functionality. In this paper we...

Abdelnur, Humberto; State, Radu; Chrisment, Isabelle; Popi, Cristian

128

Holistic VoIP Intrusion Detection and Prevention System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

VoIP security is crucial for current and future networks and services. The rapid shift from a closed and confined telephony towards an all IP network supporting end to end VoIP services provides major challenges to the security plane. Faced with multiple attack vectors, new and comprehensive defensi...

Nassar, Mohamed; Niccolini, Saverio; State, Radu; Ewald, Thilo

129

Intrusion detection mechanisms for VoIP applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

VoIP applications are emerging today as an important component in business and communication industry. In this paper, we address the intrusion detection and prevention in VoIP networks and describe how a conceptual solution based on the Bayes inference approach can be used to reinforce the existent ...

Nassar, Mohamed; State, Radu; Festor, Olivier

130

Flexible thermochromic window based on hybridized VO2/graphene.  

UK PubMed Central (United Kingdom)

Large-scale integration of vanadium dioxide (VO2) on mechanically flexible substrates is critical to the realization of flexible smart window films that can respond to environmental temperatures to modulate light transmittance. Until now, the formation of highly crystalline and stoichiometric VO2 on flexible substrate has not been demonstrated due to the high-temperature condition for VO2 growth. Here, we demonstrate a VO2-based thermochromic film with unprecedented mechanical flexibility by employing graphene as a versatile platform for VO2. The graphene effectively functions as an atomically thin, flexible, yet robust support which enables the formation of stoichiometric VO2 crystals with temperature-driven phase transition characteristics. The graphene-supported VO2 was capable of being transferred to a plastic substrate, forming a new type of flexible thermochromic film. The flexible VO2 films were then integrated into the mock-up house, exhibiting its efficient operation to reduce the in-house temperature under infrared irradiation. These results provide important progress for the fabrication of flexible thermochromic films for energy-saving windows.

Kim H; Kim Y; Kim KS; Jeong HY; Jang AR; Han SH; Yoon DH; Suh KS; Shin HS; Kim T; Yang WS

2013-07-01

131

VoIP makes voice heard--functionality is up.  

Science.gov (United States)

Phil Wade, sales and marketing director, and Mathew Wakelam, VoIP product manager, at alarm and communication specialist Static Systems Group, discuss wireless VoLP's potential in healthcare establishments and examine how, in particular, the technology can be successfully integrated with nurse call systems. PMID:18552104

Wade, Phil; Wakelam, Mathew

2008-05-01

132

Adapting Legacy Phone Systems to VoIP  

Science.gov (United States)

Created and presented by Vincente D'Ingianni, Director of Professional Services at Binary Systems, Inc., this PowerPoint demonstration covers how to adapt a Legacy phone system to Voice-over-Internet Protocol (VoIP). In the demonstration, D'Ingianni covers VoIP gateways, Bandwidth, Softswitches, and carriers.

Dã¢ââingianni, Vincente

2008-10-27

133

The Incidence of V?O2 plateau at V?O2max in a Cardiac-Diseased Population.  

UK PubMed Central (United Kingdom)

We sought to determine the incidence of V?O2 plateau at V?O2max in a cardiovascular-diseased (CVD) population using 4 different sampling intervals (15-breath moving average, 15 s, 30 s, and 60 s) and 3 different V?O2 plateau criteria (?50 mL · min-1, ?80 mL · min-1, and ?150 mL · min-1). A total of 69 people (62±10 yrs.) with recently diagnosed CVD performed a maximal exercise test (10:07±2:24 min) on a treadmill. The test was classified as maximal (n=57, 2 430±605 mL · min-1) if self-terminated due to fatigue or classified as symptom-limited (n=12, 1 683±438 mL · min-1) if symptoms presented. Chi-square analysis revealed a significant (p<0.05) effect of sampling interval on incidence of V?O 2 plateau at V?O 2max across all 3 V?O 2 plateau criteria. The sampling interval had an increasingly stronger influence on the incidence of V?O 2 plateau at V?O 2max with smaller criterion thresholds as evidenced by the Cramer's V statistics: [?50 mL · min-1 (Cramer's V=0.548, p<0.05], ?80 mL · min-1 [Cramer's V=0.489, p<0.05], ?150 mL · min-1 [Cramer's V=0.214, p<0.05]. Incidence of V?O2 plateau at V?O 2max in CVD individuals is significantly influenced by the sampling interval applied. Based on our findings we recommend a15 breath moving average and V?O 2 plateau criterion of ?50 mL · min-1.

Nolan PB; Maddison R; Dalleck L

2013-08-01

134

Fabrication, structural and electrical characterization of VO2 nanowires  

International Nuclear Information System (INIS)

The structural and electrical properties of VO2 nanowires synthesized on Si3N4/Si substrates or molybdenum grids by a catalyst-free vapour transport method were investigated. The grown VO2 nanowires are single crystalline and rectangular-shaped with a preferential axial growth direction of [1 0 0], as examined with various structural analyses such as transmission electron microscopy, electron diffraction, X-ray diffraction, and X-ray photoelectron spectroscopy. In particular, it was found that growing VO2 nanowires directly on Si3N4 deposited molybdenum transmission electron microscopy grids is advantageous for direct transmission electron microscopy and electron diffraction characterizations, because it does not involve a nanowire-detachment step from the substrates that may cause chemical residue contamination. In addition to structural analyses, VO2 nanowires were also fabricated into field effect transistor devices to characterize their electrical properties. The transistor characteristics and metal-insulator transition effects of VO2 nanowires were investigated.

2008-07-01

135

High level runners are able to maintain a VO2 steady-state below VO2max in an all-out run over their critical velocity.  

UK PubMed Central (United Kingdom)

During prolonged and intense running exercises beyond the critical power level, a VO2 slow component elevates VO2 above predicted VO2-work rates calculated from exercise performed at intensities below the lactate threshold. In such cases, the actual VO2 value will increase over time until it reaches VO2max. The aims of the present study were to examine whether the VO2 slow component is a major determinant of VO2 over time when running at a speed beyond critical velocity, and whether the exhaustion latency period at such intensity correlates with the magnitude of the VO2 slow component. Fourteen highly trained long-distance runners performed four exhaustive runs, each separated by one week of light training. VO2 and the velocity at VO2max (vVO2max) were determined for each by a graded treadmill exercise. The critical velocity (86.1 +/- 1.5% vVO2max) of each runner was calculated from exhaustive treadmill runs at 90, 100 and 105% of vVO2max. During supra-critical velocity runs at 90% of vVO2max, there was no significant rise in VO2max (20.9 +/- 2.1 ml min-1 kg-1 between the third and last min of tlim 90), such that the runners reached a VO2 steady-state, but did not reach their vVO2max level over time (69.5 +/- 5.0 vs 74.9 +/- 3.0 ml min-1 kg-1). Thus, subjects' time to exhaustion at 90% of vVO2max was not correlated with the VO2max slow component (r = 0.11, P = 0.69), but significantly correlated with the lactate threshold (r = 0.54, P = 0.04) and the critical velocity (% vVO2max; r = 0.65, P = 0.01). In conclusion, the present study demonstrates that for highly trained long-distance runners performing exhaustive, supra-critical velocity runs at 90% of vVO2max, there was not a VO2 slow component tardily completing the rise of VO2. Instead, runners will maintain a VO2 steady-state below VO2max, such that the time to exhaustion at 90% of vVO2max for these runners is positively correlated with the critical velocity expressed as % of vVO2max.

Billat V; Binsse V; Petit B; Koralsztein JP

1998-02-01

136

INFLUÊNCIA DO GÊNERO NOS TESTES DE VO2MÁX E RAST EM ATLETAS DE ATLETISMO  

Directory of Open Access Journals (Sweden)

Full Text Available A manutenção de níveis ótimos de potência muscular e a recuperação rápida são imprescindíveis para o bomdesempenho no atletismo. O objetivo do estudo foi de comparar entre os gêneros a média dos escores deVO2máx e do RAST e correlacionar os níveis de VO2 máx e o índice de fadiga com os níveis de potênciamáxima e média. A amostra foi constituída de n=24 atletas com 16.3±2.51 anos, sendo n=12 do GêneroMasculino (GM) e n=12 do Gênero Feminino (GF). Considerou os níveis significativos p<0,05. Foramobtidos os seguintes resultados no RAST; Potência Máxima (GM) e (GF) 434.6±122.7 Watts e 293.8±66.2Watts (p=0.03); Potência Média 367±101.9 Watts; 226.6±53.0 Watts (p=0.02) e na Potência Mínima302.5±80.2 Watts e 237.2±206.6 Watts (p=0.00). Nos valores relativos, (GM) e (GF) a Potência Máxima foide 7.05±1.70 Watts/Kg e 5.49±1.22 Watts/Kg (p=0.02); Potência Média 5.95±1.36 Watts/Kg e 4.22±0.99Watts/Kg (p=0,01); Potência Mínima 4.89±1.07 Watts/Kg e 3.06±1.27 Watts/Kg (p=0,01). No VO2máx o(GM) (GF) obtiveram 41.1±6.2 ml.(kg.min)-¹ e 32.6±6.4 ml.(kg.min)-¹ (p=0.00). Encontrou uma correlaçãono VO2máx e Potência Máxima (r= 0.6744 / p= 0.01), VO2máx e a Potência Média (r= 0.8227 / p= 0.00),Potência Máxima e o Índice de Fadiga (r= 0.7326 / p= 0.00). Conclui-se que as diferenças significativasencontradas nos valores de potências máxima, média e mínima (Watts) (Watts/Kg), ratificam estudosanteriores. A correlação do VO2máx e a potência média, apontam para uma possível relação direta, fato que,se confirmado, pode ajudar a entender resultados de atletas de vários níveis.

Ronaldo Nascimento Maciel; Híller Franco Entringer; Marcelo da Silva Machado; Anderson Pontes Morales

2011-01-01

137

Crystal structure of {alpha}-AgVO{sub 3} and phase relation of AgVO{sub 3}  

Energy Technology Data Exchange (ETDEWEB)

Phase relations of AgVO{sub 3} were studied by crystal structure analysis and thermal property measurement. Crystal structure of newly defined {alpha}-AgVO{sub 3} was determined by XRD measurements. The structure analyzed is monoclinic [C2/c({number_sign}15)] and the crystal parameters are a = 10.437 {angstrom}, b = 9.897 {angstrom}, c = 5.532 {angstrom}, and {beta} = 99.69{degree}, {alpha}-AgVO{sub 3} is a metastable phase which can be formed by precipitation at an ambient temperature and/or when it is quenched from its melted state. It is also formed just below the melting point instantaneously when cooled slowly and frozen quickly. {alpha}-AgVO{sub 3} is irreversibly transformed into {beta}-AgVO{sub 3} at around 200 C. The {beta}-phase is molten at 476 C.

Kittaka, Shigeharu; Matsuno, Kosaku; Akashi, Haruo [Okayama Univ. of Science (Japan)

1999-02-01

138

Lessons learnt in building VO resources: binding together several VO standards into an operational service  

CERN Multimedia

The International Virtual Observatory Alliance (IVOA) developed numerous interoperability standards during the last several years. Most of them are quite simple to implement from the technical point of view and even contain "SIMPLE" in the title. Does it mean that it is also simple to build a working VO resource using those standards? Yes and no. "Yes" because the standards are indeed simple, and "no" because usually one needs to implement a lot more than it was thought in the beginning of the project so the time management of the team becomes difficult. In our presentation we will start with a basic case of a simple spectral data collection. Then we will describe several examples of small" technologically advanced VO resources built in CDS and VO-Paris and will show that many standards are hidden from managers' eyes at the initial stage of the project development. The projects will be: (1) the GalMer database providing access to the results of numerical simulations of galaxy interactions; (2) the full spectr...

Chilingarian, Igor; Louys, Mireille; Sidaner, Pierre Le

2011-01-01

139

PRODUCCIÓN DE BIOMASA Y EXOPOLISACÁRIDOS DE Grifóla frondosa BAJO CULTIVO SUMERGIDO UTILIZANDO FUENTES DE CARBONO NO CONVENCIONALES  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Grifóla frondosa es un hongo Basidiomycete comestible y medicinal que produce polisacáridos tipo glucanos (?-1,6 y ?-1,3) con actividad antitumoral e inmunomoduladora. Para el presente trabajo, el objetivo fue evaluar la incidencia de diferentes fuentes de carbono (FC) en la producción de biomasa y exopolisacári-dos (EPS), bajo condiciones de cultivo sumergido, utilizando un diseño estadístico factorial con dos factores: fuente de carbono (FC(1-7)) y medio (more) (MB y MS). La máxima producción de biomasa micelial (21,10 ± 0,82) g/l y la máxima producción de EPS (6,53 ± 0,14) g/l se logró utilizando el medio MB suplementado con FC4. Además de lo anterior, se logró desarrollar un medio de cultivo que cumple con el objetivo de disminuir costos, de Col $18.455 a $656 por litro de medio, produciendo (14,14 ± 0,82) g/l de biomasa y (5,16 ± 0,14) g/l de EPS, utilizando el medio MS suplementando con FC4. Estos resultados abren nuevas alternativas y posibilidades en nuestro país para el desarrollo de productos a partir de esta especie con costos que estén al alcance de la población. Abstract in english Grifóla frondosa is a Basidiomycete fungus edible and medicinal, it produces polysaccharides such a glucans (?-1,6 and ?-1,3) with anti-tumor and inmuno-stimulating activity. For this work, the aim was evaluate the incidence of different carbon sources (FC) in biomass and exo-polymer (EPS) production, under submerged culture conditions, by using a factorial statistical design with two factors: carbon source (FC(1-7)) and medium (MB and MS). The maximal yield of (more) mycelial biomass (21,10 ± 0,82) g/l and the maximal yield in EPS (6,53 ± 0,14) g/l was achieved by using the MB medium supplemented with FC4. Besides, it was possible to develop a medium that fulfills the objective of reducing costs from $18.455 to $656 Colombian pesos for each liter of medium used, which produces (14,14 ± 0,82) g/l of biomass and (5,16 ± 0,14) g/l of EPS, using the MS medium supplemented with FC4. This result opens new alternatives and possibilities in our country for developing products of this species with cost that can be reached by population.

Zapata, Paula; Rojas, Diego; Fernández, Carlos; Ramírez, David; Restrepo, Gloria; Orjuela, Viviana; Arroyave, Marcela; Gómez, Tatiana; Atehortüa, Lucía

2007-06-01

140

Reproducibility of maximum aerobic power (VO2max) among soccer players using a modified heck protocol/ Reprodutibilidade da potência aeróbia máxima (VO2max) em jogadores de futebol utilizando o protocolo de heck modificado  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese OBJETIVO: Determinar o grau de reprodutibilidade do consumo máximo de oxigênio (VO2max) em jogadores de futebol utilizando o protocolo de Heck modificado. MÉTODOS: Foram avaliados por duas vezes, com intervalo de 15 dias entre os testes, 11 futebolistas masculinos. Todos eram de alto nível, treinavam em média 10 horas por semana subdivididos em treinamentos físicos, técnicos, táticos e jogos competitivos, totalizando cinco vezes por semana e na fase em que foram a (more) valiados se encontravam em pleno período competitivo realizando um jogo por semana. Os futebolistas foram avaliados em esteira ergométrica (1,2 km.h-1) a cada dois minutos e inclinação fixa durante o teste em 3%. O VO2max foi medido diretamente utilizando analisador metabólico de análise de gases expirados respiração-a-respiração. RESULTADOS: A velocidade máxima de corrida e o VO2max atingido nos dois testes foram respectivamente: (15,6 ± 1,1 vs. 15,7 ± 1,2 km.h-1; [p = 0,78]) e (54,5 ± 3,9 vs. 55,2 ± 4,4 ml.kg-1.min-1; [P = 0,88]). Houve correlação significante e alta do VO2max entre os dois testes após 15 dias de intervalo [r = 0,97; P Abstract in english OBJECTIVE: To determine the degree of reproducibility of maximum oxygen consumption (VO2max) among soccer players, using a modified Heck protocol. METHODS: 2 evaluations with an interval of 15 days between them were performed on 11 male soccer players. All the players were at a high performance level; they were training for an average of 10 hours per week, totaling 5 times a week. When they were evaluated, they were in the middle of the competitive season, playing 1 match (more) per week. The soccer players were evaluated on an ergometric treadmill with velocity increments of 1.2 km.h-1 every 2 minutes and a fixed inclination of 3% during the test. VO2max was measured directly using a breath-by-breath metabolic gas analyzer. RESULTS: The maximum running speed and VO2max attained in the 2 tests were, respectively: (15.6 ± 1.1 vs. 15.7 ± 1.2 km.h-1; [P = .78]) and (54.5 ± 3.9 vs. 55.2 ± 4.4 ml.kg-1.min-1; [P = .88]). There was high and significant correlation of VO2max between the 2 tests with a 15-day interval between them [r = 0.97; P

Santos-Silva, Paulo Roberto; Fonseca, Alfredo José; Castro, Anita Weigand de; Greve, Júlia Maria D'Andréa; Hernandez, Arnaldo José

2007-01-01

 
 
 
 
141

Reinvestigation of the synthesis of LiFeVO4  

International Nuclear Information System (INIS)

Highlights: ? We reinvestigated the synthesis of the LiFeVO4 compound. ? We demonstrate that the recently reported LiFeVO4 phase is not a pure phase. ? We proved by Rietveld refinement that LiFeVO4 is a mixture ofLiVO3 and Fe2O3. ? We noticed some attempts to fraud (modification of the powder pattern) . - Abstract: The synthesis of LiFeVO4 composition has been performed in air starting from Li2CO3, Fe2O3, and V2O5 and using the standard solid-state reaction route reported by Refs. . Identical X-ray diffraction pattern has been obtained, however our careful analysis with MDI Jade 5.0 software does not agree with previously reported pure LiFeVO4 samples. The powder pattern has been perfectly indexed using the single crystal data of LiVO3 (C2/c, a = 10.16718 A, b = 8.415725 A, c = 5.884155 A and ? = 110.489o) and ?-Fe2O3 (R-3c, a = 5.035 A, c = 13.75 A).

2011-07-15

142

A new incremental test for VO?max accurate measurement by increasing VO?max plateau duration, allowing the investigation of its limiting factors.  

Science.gov (United States)

The purpose of this study was to (1) validate a new exercise protocol for accurate measurement of VO(2max) by obtention of a VO(2max) plateau for all subjects fit and unfit (2) test the hypothesis that VO(2max) plateau duration is not correlated with VO(2max) and (3) verify that limiting factors of VO(2max) plateau duration are different from those of VO(2max) amplitude. Therefore, 14 subjects performed two incremental cycling tests: (1) a classical incremental test (CIT) to determine VO(2max), the power at VO(2max) (PVO(2max)) and at the lactate threshold (PLT) (2) a new incremental test (NIT) in which the power was decreased just after the subject reached VO(2max). During both protocols, heart rate, stroke volume, cardiac output, the arterio-venous difference and the oxygen blood saturation were recorded. The results showed that, with the NIT, subject could maintain a long VO(2max) plateau (6 ± 3 min), even those who could not reach VO(2max) plateau at the end of CIT (n = 5). The VO(2max) plateau duration was not correlated with VO(2max) amplitude which was correlated with the power at SV(max) (r = 0.888, p < 0.001). The VO(2max) plateau duration was correlated with the power decrease (W/s) during the VO(2max) plateau (r = -0.72, p = 0.003) but not with cardiac-related factors nor with PVO(2max). In conclusion, these experiments showed that it was possible to get a long VO(2max) plateau at the end of NIT whatever the individual VO(2max) amplitude was. The limiting factor of VO(2max) duration was the power output. PMID:21997677

Petot, Hélène; Meilland, Renaud; Le Moyec, Laurence; Mille-Hamard, Laurence; Billat, Véronique L

2011-10-14

143

A new incremental test for VO?max accurate measurement by increasing VO?max plateau duration, allowing the investigation of its limiting factors.  

UK PubMed Central (United Kingdom)

The purpose of this study was to (1) validate a new exercise protocol for accurate measurement of VO(2max) by obtention of a VO(2max) plateau for all subjects fit and unfit (2) test the hypothesis that VO(2max) plateau duration is not correlated with VO(2max) and (3) verify that limiting factors of VO(2max) plateau duration are different from those of VO(2max) amplitude. Therefore, 14 subjects performed two incremental cycling tests: (1) a classical incremental test (CIT) to determine VO(2max), the power at VO(2max) (PVO(2max)) and at the lactate threshold (PLT) (2) a new incremental test (NIT) in which the power was decreased just after the subject reached VO(2max). During both protocols, heart rate, stroke volume, cardiac output, the arterio-venous difference and the oxygen blood saturation were recorded. The results showed that, with the NIT, subject could maintain a long VO(2max) plateau (6 ± 3 min), even those who could not reach VO(2max) plateau at the end of CIT (n = 5). The VO(2max) plateau duration was not correlated with VO(2max) amplitude which was correlated with the power at SV(max) (r = 0.888, p < 0.001). The VO(2max) plateau duration was correlated with the power decrease (W/s) during the VO(2max) plateau (r = -0.72, p = 0.003) but not with cardiac-related factors nor with PVO(2max). In conclusion, these experiments showed that it was possible to get a long VO(2max) plateau at the end of NIT whatever the individual VO(2max) amplitude was. The limiting factor of VO(2max) duration was the power output.

Petot H; Meilland R; Le Moyec L; Mille-Hamard L; Billat VL

2012-06-01

144

Optical properties for the Mott transition in VO2  

Directory of Open Access Journals (Sweden)

Full Text Available The relationship between the first-order metal-insulator transition (MIT) and the structural phase transition (SPT) in VO2 film is analyzed by dielectric function, optical conductivity, plasma energy, and electrical conductivity. The MIT and SPT temperatures in VO2 films were approximately 68 and 75 °C, respectively, with an intermediate phase existing between 68 and 75 °C. The optical and electrical results indicate that the first-order MIT in VO2 films is not driven by the SPT.

Manil Kang; Sok Won Kim; Ji-Wook Ryu; Taejong Noh

2012-01-01

145

Gipsy 3D: Analysis, Visualization and Vo-Tools  

CERN Multimedia

The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with ad- vanced users. One of the main goals is to provide local interoperability between GIPSY (visualization and data analysis) and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

Ruiz, J E; Espigares, V; Verdes-Montenegro, L; Van der Hulst, J M

2009-01-01

146

GIPSY 3D: Analysis, Visualization and VO Tools for Datacubes  

Science.gov (United States)

The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with advanced users. One of the main goals is to provide local interoperability between GIPSY and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

Ruíz, J. E.; Santander-Vela, J. D.; Espigares, V.; Verdes-Montenegro, L.; van der Hulst, J. M.

2009-09-01

147

GIPSY 3D: Analysis, visualization and VO-Tools  

Science.gov (United States)

The scientific goals of the AMIGA project are based on the analysis of a significant amount of spectroscopic 3D data. In order to perform this work we present an initiative to develop a new VO compliant package, including present core applications and tasks offered by the Groningen Image Processing System (GIPSY), and new ones based on use cases elaborated in collaboration with advanced users. One of the main goals is to provide local interoperability between GIPSY (visualization and data analysis) and other VO software. The connectivity with the Virtual Observatory environment will provide general access to 3D data VO archives and services, maximizing the potential for scientific discovery.

Ruíz, J. E.; Santander-Vela, J. D.; Espigares, V.; Verdes-Montenegro, L.; van der Hulst, J. M.

2009-07-01

148

VoIP emergency calling foundations and practice  

CERN Multimedia

This book provides a comprehensive view of the emerging standards for VoIP emergency calling from an International perspective In this book, the authors provide a treatment of the VoIP emergency calling process that is both comprehensive, looking at all aspects of emergency calling, and practical, providing technical details on how such functions can be implemented. In addition, the authors describe the standardization efforts of the Internet Engineering Task Force who are currently working to improve the situation for VoIP emergency calls. The book provides an overview of emergency c

Wolf, Karl Heinz

2010-01-01

149

Thermal properties of a novel compound PbVO3  

International Nuclear Information System (INIS)

[en] Effect of pressure on thermal properties of a multiferroic (MF) novel compound PbVO3 is studied using an atomistic approach. The temperature dependence of the specific heat (CP) (20K ? T ? 300 K) of PbVO3 has been studied and compared with the earlier experimental work. Also, this work reports, probably for the first time the relation of pressure to the Debye temperature (?D) along with other properties like bulk modulus (B), molecular force constant (f), Reststrahlen frequency (?0), thermal expansion (?) and Grüneisen parameter of PbVO3 with the Modified Rigid Ion Model (MRIM).

2012-07-30

150

Explanation of the similarity of the experimental photoemission spectra of SrVO3 and CaVO3  

CERN Multimedia

We present parameter-free LDA+DMFT calculations for the many-particle density of states of cubic SrVO3 and orthorhombic CaVO3. Both systems are found to be strongly correlated metals, but not on the verge of a metal-insulator transition. In spite of the considerably smaller V-O-V bonding angle in CaVO3 the photoemission spectra of the two systems are very similar, their quasiparticle parts being almost identical, in agreement with recent bulk-sensitive photoemission experiments.

Nekrasov, I A; Kondakov, D E; Kozhevnikov, A V; Pruschke, T; Held, K; Vollhardt, D; Anisimov, V I; Pruschke, Th.

2002-01-01

151

Depressed Phase Transition in Solution-Grown VO2 Nanostructures  

Energy Technology Data Exchange (ETDEWEB)

The first-order metal-insulator phase transition in VO{sub 2} is characterized by an ultrafast several-orders-of-magnitude change in electrical conductivity and optical transmittance, which makes this material an attractive candidate for the fabrication of optical limiting elements, thermochromic coatings, and Mott field-effect transistors. Here, we demonstrate that the phase-transition temperature and hysteresis can be tuned by scaling VO{sub 2} to nanoscale dimensions. A simple hydrothermal protocol yields anisotropic free-standing single-crystalline VO{sub 2} nanostructures with a phase-transition temperature depressed to as low as 32 C from 67 C in the bulk. The observations here point to the importance of carefully controlling the stochiometry and dimensions of VO{sub 2} nanostructures to tune the phase transition in this system.

Whittaker, L.; Jaye, C; Fu, Z; Fischer, D; Banerjee, S

2009-01-01

152

Enhanced optical response of hybridized VO?/graphene films.  

UK PubMed Central (United Kingdom)

Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ?56 °C.

Kim H; Kim Y; Kim T; Jang AR; Jeong HY; Han SH; Yoon DH; Shin HS; Bae DJ; Kim KS; Yang WS

2013-04-01

153

Temperature-controlled surface plasmon resonance in VO (2) nanorods.  

UK PubMed Central (United Kingdom)

The optical properties of VO(2) nanoparticles formed in an amorphous SiO(2) host by stoichiometric ion implantation of vanadium and oxygen and thermal annealing have been determined and correlated with the particle size and morphology. The results show that that the temperature-controlled semiconductor-to-metal phase transition of the VO(2) nanophase precipitates turns on the classical surface plasmon resonance, with specific features that depend on the size and aspect ratio of the VO(2) particles. This effect improves the optical contrast between the metallic and semiconducting states in the near-IR region of the spectrum as a result of dielectric confinement that is due to the SiO(2) host. A fiber-optic application is demonstrated, as is the ability to control the characteristics of the phase transition by using ion implantation to dope the VO(2) nanoparticles with tungsten or titanium ions.

Lopez R; Haynes TE; Boatner LA; Feldman LC; Haglund RF Jr

2002-08-01

154

Density functional theory study of rutile VO2 surfaces  

CERN Document Server

We present the results of a density functional theory (DFT) investigation of the surfaces of rutile-like vanadium dioxide, VO2(R). We calculate the surface energies of low Miller index planes, and find that the most stable surface orientation is the (110). The equilibrium morphology of a VO2(R) particle has an acicular shape, laterally confined by (110) planes and topped by (011) planes. The redox properties of the (110) surface are investigated by calculating the relative surface free energies of the non-stoichiometric compositions as a function of oxygen chemical potential. It is found that the VO2(110) surface is oxidized with respect to the stoichiometric composition, not only at ambient conditions but also at the more reducing conditions under which bulk VO2 is stable in comparison with bulk V2O5. The adsorbed oxygen forms surface vanadyl species much more favorably than surface peroxo species.

Mellan, Thomas A

2012-01-01

155

[Research on optical property of phase transition VO2 films].  

Science.gov (United States)

Optical transmission spectra of VO2 films on glass, fused silica, and sapphire were recorded and analyzed during heating process. Thermally induced phase transition of VO2 films occurred at a certain temperature, associated with abrupt changes in optical properties. The transition temperature and the contrast of the optical properties depended on the substrate and the deposit method used. The change in transmittance delta T at 5 microns of VO2 films deposited on sapphire by RF magnetron sputtering was 70%, and the corresponding relative change delta T/TRT was 94%. For the VO2 films deposited on glass by RF magnetron sputtering, delta T at 2.5 microns was 64.2%, and delta T/TRT was as high as 98%. PMID:12953503

He, Chen-juan; Li, De-hua; Lu, Zhen-zhong; Nie, Yu-xin; Wang, Xue-jin; Yuan, Hong-tao; Feng, Ke-an

2003-06-01

156

Audio CAPTCHA for SIP-Based VoIP  

Science.gov (United States)

Voice over IP (VoIP) introduces new ways of communication, while utilizing existing data networks to provide inexpensive voice communications worldwide as a promising alternative to the traditional PSTN telephony. SPam over Internet Telephony (SPIT) is one potential source of future annoyance in VoIP. A common way to launch a SPIT attack is the use of an automated procedure (bot), which generates calls and produces audio advertisements. In this paper, our goal is to design appropriate CAPTCHA to fight such bots. We focus on and develop audio CAPTCHA, as the audio format is more suitable for VoIP environments and we implement it in a SIP-based VoIP environment. Furthermore, we suggest and evaluate the specific attributes that audio CAPTCHA should incorporate in order to be effective, and test it against an open source bot implementation.

Soupionis, Yannis; Tountas, George; Gritzalis, Dimitris

157

SIP based Single-line VoIP Residential Gateway  

UK PubMed Central (United Kingdom)

A Voice over IP (VoIP) Gateway is one of thevarious components used in realizing theconvergence of data and telephone networks. Itrefers to an entity that enables voicecommunication between callers on the IPnetwork and the public switched telephonenetwork (PSTN).

Mohit Lad; Manish Jalan; Deepali Patil; Hya Sule

158

Enhanced optical response of hybridized VO2/graphene films  

Science.gov (United States)

Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ~56 °C.Application of graphene as transparent electrodes is an active research area due to its excellent electrical and optical properties. Vanadium dioxide (VO2) is an attractive material since it is a thermochromic material that undergoes a structural phase transition when heat is applied. The phase transition results in the change of electrical and optical characteristics. We report optical characteristics of hybrid materials of graphene and VO2. We observed a 12% improvement in infrared transmittance with VO2 films deposited on graphene sapphire substrates compared to that of bare sapphire substrates. We also found that the phase transition temperature decreases as the number of graphene layers on the substrates increases. In the case of VO2 films on the substrate that was coated with four layers of graphene, the mean phase transition temperature was lowered to ~56 °C. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34054f

Kim, Hyeongkeun; Kim, Yena; Kim, Taeyoung; Jang, A.-Rang; Jeong, Hu Young; Han, Seung Ho; Yoon, Dae Ho; Shin, Hyeon Suk; Bae, Dong Jae; Kim, Keun Soo; Yang, Woo Seok

2013-03-01

159

Doping of VO2 thin films by ion implantation  

International Nuclear Information System (INIS)

[en] Ion implantation is used to dope VO2 thin films and is compared with other doping technologies. Argon, boron, and phosphorus are chosen as doping materials. The influence of doping on the resistance-temperature dependence of the VO2 films is measured in different annealing states after implantation. Doping with P-ions results in a strong decrease of the transition temperature, while an influence of doping with Ar- and B-ions is not observed. (author)

1977-07-16

160

Mathematical Representation of VoIP Connection Delay  

Directory of Open Access Journals (Sweden)

Full Text Available The main topic of this article is to define mathematical formulation of VoIP connection delay model. It handles about all partial delay components, the mechanism of their generation, facilities and their mathematical formulation. Thereafter based on mathematical formulation of all partial delay components, the final mathematical model of whole VoIP call delay is created. In conclusion of this article the results of the designed mathematical model are compared with the experimentally gained results.

I. Baronak; M. Halas

2007-01-01

 
 
 
 
161

Fair Scheduling for Delay-Sensitive VoIP Traffic  

Science.gov (United States)

With the wide expansion of voice services over the IP networks (VoIP), the volume of this delay sensitive traffic is steadily growing. The current packet schedulers for IP networks meet the delay constraint of VoIP traffic by simply assigning its packets the highest priority. This technique is acceptable as long as the amount of VoIP traffic is relatively very small compared to other non-voice traffic. With the notable expansion of VoIP applications, however, the current packet schedulers will significantly sacrifice the fairness deserved by the non-voice traffic. In this paper, we extend the conventional Deficit Round-Robin (DRR) scheduler by including a packet classifier, a Token Bucket and a resource reservation scheme and propose an integrated packet scheduler architecture for the growing VoIP traffic. We demonstrate through both theoretical analysis and extensive simulation that the new architecture makes it possible for us to significantly improve the fairness to non-voice traffic while still meeting the tight delay requirement of VoIP applications.

Ahmed, Shawish; Jiang, Xiaohong; Horiguchi, Susumu

162

The preparation of a plasmonically resonant VO2 thermochromic pigment.  

UK PubMed Central (United Kingdom)

Vanadium dioxide (VO(2)) undergoes a reversible metal-insulator transition, normally at approximately 68 degrees C. While the properties of continuous semi-transparent coatings of VO(2) are well known, there is far less information available concerning the potential use of discrete VO(2) nanoparticles as a thermochromic pigment in opaque coatings. Individual VO(2) nanoparticles undergo a localized plasmon resonance with near-infrared light at about 1100 nm and this resonance can be switched on and off by simply varying the temperature of the system. Therefore, incorporation of VO(2) nanoparticles into a coating system imbues the coating with the ability to self-adaptively modulate its own absorptive efficiency in the near-infrared. Here we examine the magnitude and control of this phenomenon. Prototype coatings are described, made using VO(2) powder produced by an improved process. The materials are characterized using calorimetry, x-ray diffraction, high-resolution scanning electron microscopy, transmission electron microscopy, and by measurement of optical properties.

Bai H; Cortie MB; Maaroof AI; Dowd A; Kealley C; Smith GB

2009-02-01

163

Model experiments on Na pool fire  

International Nuclear Information System (INIS)

[en] In Na-cooled Fast Breeder Hazard Analysis for a Na pool fire in the reactor containment vessel, Na fire model experiments have been carried out with a 3.2 m3 closed vessel of height 2 m and diameter 1.5 m. The burning areas used are 0.3, 0.15 and 0.075 m2. For the different initial Na temperatures, initial oxygen contents and atmospheric humidities, the burning rate was estimated from change of the oxygen content in the atmosphere, gas density or generated heat. The Na surface burning rate of initial temperature 5000C in the closed air with 21 v/o oxygen depends strongly on the ratio of Na surface area and sectional (bottom) area of the reaction vessel. The apparent burning rate is nearly constant. Below 5 v/o oxygen, at least, the mild oxidation without brightness proceeds in first-order reaction with the oxygen content. (author)

1975-01-01

164

Efecto de nutrientes sobre la producción de biomasa del hongo medicinal Ganoderma lucidum/ Effect of nutrients in the biomass production of the medicinal mushroom Ganoderma lucidum  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El hongo Ganoderma lucidum, en los constituyentes de su biomasa, tiene compuestos con propiedades benéficas para la salud; es por esto que el conocimiento de las condiciones nutricionales adecuadas para su crecimiento permitirá su producción industrial y a bajo costo. En este trabajo se evaluó a nivel de matraz el efecto de la relación C/N, y la presencia de diferentes fuentes de carbono, nitrógeno y micronutrientes sobre la producción de biomasa. Empleando glucosa (more) y peptona como fuentes de carbono y nitrógeno, respectivamente, se encontró una relación C/N óptima de 16,7:1 para la cual la máxima producción de biomasa fue de 25 g/L. Manteniendo esta relación C/N, y sustituyendo la glucosa por lactosa o harina de cebada y la peptona por extracto de levadura, la producción de biomasa se incrementó a 35 g/L. En presencia de harina de cebada la adición al medio de cultivo de sales de Mg y K, y de tiamina, no generó un mayor incremento en la producción de biomasa. La producción de biomasa de G. lucidum se ve favorecida por la presencia en el medio de cultivo de relaciones C/N cercanas a las reportadas conforme a la composición típica de los hongos, así como por la presencia de sustratos complejos como la harina de cebada que le aportan además de la fuente de carbono micronutrientes necesarios para su desarrollo. Abstract in english Ganoderma lucidum fungus has some biomass components with beneficial health properties. The knowledge about its nutritionals requirements for growing will favor its industrial production at lower cost. In this work, the effect of C/N ratio, the presence of different carbon, nitrogen and micronutrients sources, on fungal biomass production, were evaluated. Using glucose and peptone as carbon and nitrogen sources, respectively, an optimal C/N ratio of 16,7:1 was found, for (more) which the maximal biomass production was 25 g/L. Replacing glucose by lactose or barley flour and peptone by yeast extract at the same C/N ratio, the biomass production was enhanced to 35 g/L. With barley flour in the culture medium, the presence of Mg and K salts and thiamine did not turn out into a major increase of biomass. The G. lucidum biomass production is promoted by C/N ratios in the culture medium nearly equivalent to that found in the fungus, as well as the presence of complex substrates as barley flour which, additionally, contributes with important micronutrients along with the carbon source.

Torres López, Ana María; Quintero Díaz, Juan Carlos; Atehortua Garcés, Lucía

2011-07-01

165

Neutron diffraction study of YVO3, NdVO3, and TbVO3  

CERN Multimedia

The structural and magnetic properties of YVO3, NdVO3 and TbVO3 were investigated by single-crystal and powder neutron diffraction. YVO3 shows a structural phase transition at 200 K from an orthorhombic structure with the space group Pbnm to a monoclinic one with the space group P21/b. But supplementary high-resolution synchrotron diffraction experiments showed that the monoclinic distortion is extremely small. A group theoretical analysis shows that this magnetic state in the monoclinic phase is incompatible with the lattice structure, unless terms of higher than bilinear order in the spin operators are incorporated in the spin Hamiltonian. This observation is discussed in the light of recent theories invoking unusual many-body correlations between the vanadium t2g orbitals. A structural phase transition back to the orthorhombic space group Pbnm is observed upon cooling below 77 K. This transition is accompanied by a rearrangement of the magnetic structure into a mode compatible with the lattice structure. T...

Reehuis, M; Pattison, P; Ouladdiaf, B; Rheinstädter, M C; Ohl, M; Regnault, L P; Miyasaka, M; Tokura, Y; Keimer, B

2006-01-01

166

Chemical and sonochemical approaches to the formation of VO{sub 2} films and VO{sub 2}-impregnated materials  

Energy Technology Data Exchange (ETDEWEB)

A new chemical and chemical/ultrasonic approach to the preparation of VO{sub 2} films and VO{sub 2}-impregnated bulk materials has been developed. In this approach, a V{sub 2}O{sub 5} sol prepared by quenching is used to coat SiO{sub 2} substrates. The resulting gel-film is heat treated in a reducing atmosphere to form a film identified as VO{sub 2} from the results of X-ray diffraction and both optical and resistivity measurements, which reveal the phase transition characteristic of vanadium dioxide. The advantage of this approach to the formation of VO{sub 2} is that the V{sub 2}O{sub 5} sol can be used to impregnate porous materials, which are then heated treated to form an optically active composite material. The switching properties of the VO{sub 2} films are investigated using optical and resistivity measurements, and the results are compared to those obtained for VO{sub 2}-films prepared by more-conventional methods.

Keppens, V.; Mandrus, D.; Boatner, L.A. [Oak Ridge National Lab., TN (United States). Solid State Div.

1997-11-01

167

Acumulación y distribución de biomasa en Leucaena leucocephala (lam) de Wit., durante la fase de establecimiento. I. Repartición de biomasa/ Accumulation and distribution of biomass in Leucaena leucocephala (Lam.) de wit during the phase of establishment. II. Repartitioning of biomass  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En el presente estudio se comparó el patrón de acumulación de biomasa aérea y radical durante los primeros 110 días después de la germinación (DDG), en tres líneas de Leucaena leucocephala (CIAT 7984, 9438, 18477). El cv. Perú se utilizó como testigo con fines de comparación. El experimento se llevó a cabo en condiciones de invernadero, cultivándose las plantas en tubos de PVC de 1 m de alto por 0.20 m de ancho. El diseño del experimento fue un completamente (more) aleatorizado, en un arreglo factorial de 4 líneas x 5 cosechas (15, 30, 45, 60 y 110 DDG) x 5 repeticiones. Los datos fueron analizados por vía no paramétrica. Para estimar el patrón de acumulación y distribución de biomasa se midió en cada cosecha el peso seco acumulado de hojas (MSh), tallos (MSt) y raíces (MSr). A los 110 DDG, todas las líneas en general destinaron una mayor proporción de asimilados en producir hojas a expensa de tallos y raíces. La MSh no fue diferente (P Abstract in english In the present study, dry matter accumulation and the pattern of distribution between aerial and bellow-ground biomass were studied in three accessions (CIAT 7984, 9438, 18477) of Leucaena leucocephala during 110 days after germination (DAG). Cv. Perú was used as a control plant. The experiment was carried out under glasshouse conditions, where plants were grown in PVC pots (1 m height x 0.20 m diameter). A completed randomized designed was used, in a factorial arrangeme (more) nt of 4 plant materials x 5 harvests (ie. 15, 30, 45, 60 and 110 DAG) x 5 replicates. To estimate biomass accumulation and assimilates distribution within the plant, harvests of individual plants were performed and the dry weight of leaf (LDM), stems (SDM) and root (DMR) at different depths was recorded. Initially, all accessions diverted a high proportion of the available energy in producing root biomass, while by the end of the establishment period relatively more photosynthetic material was used to increase leaf and stem biomass. The MSh was not different (P

Guevara, Eunice; Guenni, Orlando

2004-04-01

168

Fatigue responses in exercise under control of VO2.  

UK PubMed Central (United Kingdom)

To examine the fatigue response during an exhaustive heavy exercise performed under control of oxygen uptake (SS@V.O (2)Delta50) or power output (SS@pDelta50), eleven trained male subjects performed an incremental test to determine the peak of the oxygen uptake value (V.O (2peak)) and lactate threshold and two exhaustive steady-state cycling exercises at the intermediate value between the lactate threshold and V.O (2peak) (SS@V.O (2)Delta50 and SS@pDelta50). The control of V.O (2) induced an oscillation of the power output, which lowered the average power output (276 +/- 47 vs. 315 +/- 40 W, p = 0.004) and cancelled the slow component of oxygen kinetics. However, all subjects reached maximal cardiac output (CO) and heart rate (HR) values which were sustained almost two times longer in SS@V.O (2)Delta50 compared to SS@pDelta50 (979 +/- 854 vs. 475 +/- 236 s, p = 0.046 for CO and 1050 +/- 890 vs. 513 +/- 288 s, p = 0.037 for HR). Furthermore, SS@pDelta50 elicited V.O (2peak) but not SS@V.O (2)Delta50 (4963 +/- 434 vs. 4723 +/- 460 mL . min (-1), p = 0.026). Finally, the time spent at the maximal CO and HR values is correlated with time to exhaustion at V.O (2)Delta50. In conclusion, the cause of fatigue does not seem to have the same origin during exhaustive supra-lactate threshold exercise under control of V.O (2) (V.O (2)Delta50) compared to constant power output (pDelta50), while both elicit the maximal HR and CO values.

Lepretre PM; Lopes P; Koralsztein JP; Billat V

2008-03-01

169

Fatigue responses in exercise under control of VO2.  

Science.gov (United States)

To examine the fatigue response during an exhaustive heavy exercise performed under control of oxygen uptake (SS@V.O (2)Delta50) or power output (SS@pDelta50), eleven trained male subjects performed an incremental test to determine the peak of the oxygen uptake value (V.O (2peak)) and lactate threshold and two exhaustive steady-state cycling exercises at the intermediate value between the lactate threshold and V.O (2peak) (SS@V.O (2)Delta50 and SS@pDelta50). The control of V.O (2) induced an oscillation of the power output, which lowered the average power output (276 +/- 47 vs. 315 +/- 40 W, p = 0.004) and cancelled the slow component of oxygen kinetics. However, all subjects reached maximal cardiac output (CO) and heart rate (HR) values which were sustained almost two times longer in SS@V.O (2)Delta50 compared to SS@pDelta50 (979 +/- 854 vs. 475 +/- 236 s, p = 0.046 for CO and 1050 +/- 890 vs. 513 +/- 288 s, p = 0.037 for HR). Furthermore, SS@pDelta50 elicited V.O (2peak) but not SS@V.O (2)Delta50 (4963 +/- 434 vs. 4723 +/- 460 mL . min (-1), p = 0.026). Finally, the time spent at the maximal CO and HR values is correlated with time to exhaustion at V.O (2)Delta50. In conclusion, the cause of fatigue does not seem to have the same origin during exhaustive supra-lactate threshold exercise under control of V.O (2) (V.O (2)Delta50) compared to constant power output (pDelta50), while both elicit the maximal HR and CO values. PMID:17879879

Lepretre, P-M; Lopes, P; Koralsztein, J-P; Billat, V

2007-09-18

170

Advantages of VoIP in the german research network  

UK PubMed Central (United Kingdom)

With the arising of telephony over the internet, loads of institutes start looking at that new technology. They ask themselves for sense and meaningful use. Many questions appeared to be answered first. The first one is about the interoperability of the end systems. It should be possible to change the vendor and implement the new devices without any problems into the existing VoIP infrastructure. These ideas led to first single VoIP labs. To increase the value of such installations, they should be interconnected. Because of the very heterogeneous hardware, which has been used by the institutes, the construction of a VoIP network has been a project for itself. Several working groups have been formed in order to examine single questions much closer. Examples are the accounting, the security and the required quality of service within the transport network. However, the research work has not finished yet. There are still unsolved questions about the accounting and the security in such a large VoIP network as it became today. Routing strategies have to be discussed as well as security questions. Maybe a single institution should start offering IP telephony as a service for the complete german research network. Currently, it is a distributed group. During the tests, VoIP has proved its position within the internet landscape as well as within the standard telephony. The participants of the VoIP project managed to configure and use the VoIP components successfully. Nevertheless, it should not be concealed that much work is still approaching.

Falko Dressler

171

Producción de biomasa de Saccharomyces cerevisiae y Candida utilis usando residuos de pulpa de Coffea arabica L  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Los avances en biotecnología industrial ofrecen oportunidades potenciales para la utilización económica de residuos agro-industriales tales como la pulpa de café, material mucilaginoso, fibroso (producto secundario) obtenido durante el proceso húmedo o seco del beneficio de las cerezas de café. El propósito de este trabajo fue utilizar los residuos de la pulpa de café, rico en materia orgánica, como sustrato para la producción de biomasa de levaduras por proceso (more) s de fermentación aeróbica. Los residuos de café se sometieron a hidrólisis con una solución de ácido sulfúrico al 2%, en una relación 10:1 (líquido:sólido), con un tamaño de partícula ? 2 mm., operando a presión atmosférica, ebullición a reflujo, durante 4 horas. El extracto ácido se filtró y se ajustó a pH 4,5 y luego se esterilizó a 120 ºC por 15 minutos. La fermentación se realizó con Saccharomyces cerevisiae y Candida utilis, medio de producción extracto de café enriquecido con sales nutritivas. Se formularon diferentes medios de producción (1,2,3 y 4), siendo el N°3, enriquecido con extracto de café hidrolizado, 1L; urea, 3g/L; fosfato ácido de potasio, 2g/L; extracto de malta, 1,3g/L y melaza, 30g/L, el cual aportó los mejores resultados. El tiempo total de fermentación fue de 8 horas. Se obtuvo 10g/L de biomasa con un incremento proteico de 7,39 a 42,5%. Se puede concluir que la pulpa de café constituye un sustrato adecuado para obtener biomasa o proteína unicelular, que podría ser destinada como suplemento en formulaciones para alimentación animal Abstract in english The advances in industrial biotechnology offer potential opportunities for the economic use of agro-industrial remainders such as the coffee pulp, mucilagenous, fibrous material (secondary product) obtained during the humid or dry process of the benefit of the coffee cherries. The intention of this work was to use the remainders of the pulp of coffee, rich in organic matter, like substrate for the production of biomass of leavenings by processes of aerobic fermentation. T (more) he coffee remainders were put under hydrolysis with a sulfuric acid solution to 2%, in a 10:1 relation (liquid: solid), with a size of particle ? 2 mm, operating to atmospheric pressure, boiling to ebb tide, during 4 hours. The acid extract filtered and it adjusted to pH 4,5 and then it sterilize to 120 ºC by 15 minutes. The fermentation was made with Saccharomyces cerevisiae and Candida utilis, the production means: extract of coffee enriched with nutritious salts. Different means from production were formulated (1,2,3 and 4), being the N°3, enriched with extract of hydrolyzed coffee, 1L; urea, 3g/L; acid potassium phosphate, 2g/L; extract of Malta, 1,3g/L and molasses, 30g/L, which contributed the best results. The total time of fermentation was of 8 hours. 10g/L of biomass with a protein increase from 7.39 to 42.5% was obtained. It is possible to be concluded that the coffee pulp constitutes an suitable substrate to obtain biomass or unicellular protein, that could be destined like supplement in formulations for feeding animal

Gualtieri A, María J; Villalta R, Carolina; Díaz T, Lorena E; Medina, Gerardo; Lapenna, Elisa; Rondón, María E

2007-12-01

172

Producción de biomasa de Saccharomyces cerevisiae y Candida utilis usando residuos de pulpa de Coffea arabica L  

Directory of Open Access Journals (Sweden)

Full Text Available Los avances en biotecnología industrial ofrecen oportunidades potenciales para la utilización económica de residuos agro-industriales tales como la pulpa de café, material mucilaginoso, fibroso (producto secundario) obtenido durante el proceso húmedo o seco del beneficio de las cerezas de café. El propósito de este trabajo fue utilizar los residuos de la pulpa de café, rico en materia orgánica, como sustrato para la producción de biomasa de levaduras por procesos de fermentación aeróbica. Los residuos de café se sometieron a hidrólisis con una solución de ácido sulfúrico al 2%, en una relación 10:1 (líquido:sólido), con un tamaño de partícula ? 2 mm., operando a presión atmosférica, ebullición a reflujo, durante 4 horas. El extracto ácido se filtró y se ajustó a pH 4,5 y luego se esterilizó a 120 ºC por 15 minutos. La fermentación se realizó con Saccharomyces cerevisiae y Candida utilis, medio de producción extracto de café enriquecido con sales nutritivas. Se formularon diferentes medios de producción (1,2,3 y 4), siendo el N°3, enriquecido con extracto de café hidrolizado, 1L; urea, 3g/L; fosfato ácido de potasio, 2g/L; extracto de malta, 1,3g/L y melaza, 30g/L, el cual aportó los mejores resultados. El tiempo total de fermentación fue de 8 horas. Se obtuvo 10g/L de biomasa con un incremento proteico de 7,39 a 42,5%. Se puede concluir que la pulpa de café constituye un sustrato adecuado para obtener biomasa o proteína unicelular, que podría ser destinada como suplemento en formulaciones para alimentación animalThe advances in industrial biotechnology offer potential opportunities for the economic use of agro-industrial remainders such as the coffee pulp, mucilagenous, fibrous material (secondary product) obtained during the humid or dry process of the benefit of the coffee cherries. The intention of this work was to use the remainders of the pulp of coffee, rich in organic matter, like substrate for the production of biomass of leavenings by processes of aerobic fermentation. The coffee remainders were put under hydrolysis with a sulfuric acid solution to 2%, in a 10:1 relation (liquid: solid), with a size of particle ? 2 mm, operating to atmospheric pressure, boiling to ebb tide, during 4 hours. The acid extract filtered and it adjusted to pH 4,5 and then it sterilize to 120 ºC by 15 minutes. The fermentation was made with Saccharomyces cerevisiae and Candida utilis, the production means: extract of coffee enriched with nutritious salts. Different means from production were formulated (1,2,3 and 4), being the N°3, enriched with extract of hydrolyzed coffee, 1L; urea, 3g/L; acid potassium phosphate, 2g/L; extract of Malta, 1,3g/L and molasses, 30g/L, which contributed the best results. The total time of fermentation was of 8 hours. 10g/L of biomass with a protein increase from 7.39 to 42.5% was obtained. It is possible to be concluded that the coffee pulp constitutes an suitable substrate to obtain biomass or unicellular protein, that could be destined like supplement in formulations for feeding animal

María J Gualtieri A; Carolina Villalta R; Lorena E Díaz T; Gerardo Medina; Elisa Lapenna; María E Rondón

2007-01-01

173

REDUCCIÓN DE LA BIOMASA DEL PINO CARRASCO (PINUS HALEPENSIS) EN UN ÁREA DEL SURESTE SEMIÁRIDO PENINSULAR COMO ESTRATEGIA PARA EVITAR EL ESTRÉS HÍDRICO  

Directory of Open Access Journals (Sweden)

Full Text Available En las épocas de fuertes sequías, la vegetación mediterránea sufre un estado de estrés hídrico prolongado que le obliga a adoptar diversas estrategias de supervivencia, entre las que fi guran, como último recurso, y antes de llegar a superar su capacidad de resilencia, la reducción de la biomasa de hojas. En este trabajo se pone de manifi esto como algunos ejemplares de Pinus halepensis existentes en el área de estudio (el campo experimental de El Ardal, Murcia), redujeron apreciablemente su biomasa aérea en respuesta a la sequía, que se manifestó en un importante aumento de la producción de hojarasca. La producción de hojarasca se relaciona además de con la precipitación registrada en el periodo de estudio, con la humedad del suelo, parámetro clave en la supervivencia de la vegetación en ambientes secos.

Francisco Belmonte Serrato; Francisco López Bermúdez; Asunción Romero Díaz

2008-01-01

174

Photon band hysteresis in VO2 photonic crystal under semiconductor-metal phase transition  

International Nuclear Information System (INIS)

[en] The VO2-based photonic crystals possessing the semiconductor-metal phase transition in temperature range of 55-75 deg C were synthesized by infiltration of opal matrices with VO2 and subsequent etching out SiO2 from opal-VO2 composites. It was found that crystals had broad photon forbidden band in the visible spectral range, whose energy location changes drastically under the phase transition. A temperature-induced displacement and thermal hysteresis of the photon forbidden band position due to the phase transition in VO2 were observed. A theoretical model of the periodic layer medium was proposed to describe quantitatively the reflection spectra of the synthesized photonic crystals of opal and VO2[ru] ??????? ???????????? VO2 ? ????????? ?????, ? ??????????? ?????????????? SiO2, ????????????? ???????? ????????? ?? ?????? VO2, ?????????? ??????? ????????? ?????????????-?????? ? ??????? ?????????? 55-75 ???? ?. ???????????, ??? ??? ??????????????? ??????? ???????? ??????????? ????? ? ??????? ??????? ???????, ?????????????? ????????? ??????? ???????? ??????? ??? ??????? ????????. ???????? ????????????? ????? ? ?????????? ????????? ???????? ??????????? ????, ????????????? ??????? ????????? ? VO2. ? ?????? ?????? ???????? ????????????? ????? ????????? ?????????????? ??????? ???????? ????????? ???????? ?????????? ????? ? VO2

2002-01-01

175

[Study on spectral property of phase transition of PcNi-VO2 films].  

UK PubMed Central (United Kingdom)

Highly oriented VO2 thin films were deposited on sapphire substrate and [C8H17O]8 PcNi thin films were spin-coated onto VO2 thin films. The microstructure of VO2 thin films was studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated with infrared spectrometer. It was found that the mid-infrared transmittance of the complex films in the wavelength range 1.5 to 5.5 mm raised with PcNi coating. The thermochromism of PcNi/VO2 films did not changed compared with VO2 films and the transition temperature was the same as that of VO2. It can be anticipated that the optical limiting property of PcNi/VO2 films will be superior to that of VO2 thin films or PcNi thin films.

Yuan HT; Feng KC; Zhang XH

2007-10-01

176

Efecto de fertilización nitrogenada en la producción de biomasa y calidad de aceite esencial en Lippia alba (Miller), Pronto alivio.  

Directory of Open Access Journals (Sweden)

Full Text Available En el Campo Experimental de la Universidad Nacional de Colombia sede Palmira (CEUNP) se realizó un ensayo para evaluar el efecto de la fertilización nitrogenada, aplicando dos fuentes (gallinaza y urea) en dos niveles (50 y 100 kg/ha de nitrógeno) y dos frecuencias de corte (dos y cuatro meses). En el lote experimental se situaron 15 parcelas, en un diseño de bloques completos al azar, con cinco tratamientos y tres repeticiones. Para el análisis de la información se utilizó el programa estadístico SAS. El máximo rendimiento de biomasa y aceites esenciales se obtuvo con la aplicación de 100 kg/ha de nitrógeno en forma de urea y la frecuencia de corte cada dos meses. Los niveles de extracción de Lippia alba en nitrógeno variaron entre 79.7 y 128.5; fósforo entre 24.5 y 30.5; potasio entre 114.6 y 138.8 y calcio entre 100 y 150 kg/ha. El aceite esencial estuvo compuesto mayoritariamente por carvona y limoneno. Palabras claves: Fertilización nitrogenada, Lippia alba, Rendimientos biomasa, aceites esenciales, pronto alivio. ABSTRACT Nitrogenous fertilization effects in the Lippia alba production and quality. In the Experimental Center of the National University of Colombia-Palmira (CEUNP) a experiment was realized to evaluate the effect of the nitrogenous fertilization, using two sources (gallinaza and urea) at two levels (50 and 100 kg/ha of nitrogen) and two cutting frequencies (each two and four months). In the experimental area 15 plots were planted, in a randomized Complete Blocks design random (RCBD) with five treatments and three repetitions to measure the following variables: production of fresh matter, content of dry matter, nutrients extraction and content of essential oils. The analysis of variance used the statistical program SAS. The maximum yield of biomass and essential was obtained oils combining the fertilization with 100 kg/ha of nitrogen as urea and the cutting frequency every of two months. The levels of nutrients extraction of Lippia alba varied between 79.7 and 128.5 kg/ha of nitrogen, 24.5 and 30.5 kg/ha of phosphorus, 114.6 and 138.8 Kg/ha of potassium and between 100 y 150 kg/ha of Calcium. The phytochemical analyses showed that the essential oil was mainly composed by carvona and limoneno. Key words: Nitrogenous Fertilization, Lippia alba, yields, biomass, essential oils.

Hernández V. H.; Bonilla C C.; Sánchez O. M.

2004-01-01

177

Correlação entre as medidas direta e indireta do VO2max em atletas de futsal Correlación entre las medidas directa e indirecta del VO2max en atletas de futsal Correlation between direct and indirect VO2max measurements in indoor soccer players  

Directory of Open Access Journals (Sweden)

Full Text Available A importância das qualidades morfofuncionais na melhora do rendimento nos esportes aumentou o interesse no aprimoramento dos níveis de aptidão física dos atletas. No entanto, há poucos estudos sobre as variáveis fisiológicas do futsal disponíveis na literatura científica mundial. Dessa forma, o objetivo deste estudo foi verificar a existência de correlação entre os testes de medida direta e indireta do VO2max, em jogadores de futsal. Foram analisados 13 jogadores de futsal, com idade de 18,6 ± 1,9 anos, altura igual a 177,1 ± 3,5cm, peso de 68,5 ± 9,5kg, índice de massa corporal (IMC) de 21,7 ± 2,3kg/m². Para medida direta do VO2max foi utilizado o sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) e para mensuração indireta do VO2max foi realizado o teste de campo de 3.200m. A análise estatística foi elaborada através do teste t de Student para amostras pareadas e pelo coeficiente de correlação de Pearson. Os valores de VO2max obtidos no teste de medida direta não apresentaram diferenças significativas em relação à medida indireta (62,8 ± 10,1 vs. 58,5 ± 8,5ml/kg/min, respectivamente). Quando correlacionados os valores de VO2max obtidos em ambos os testes, observou-se forte correlação (r = 0,72). Em conclusão, os testes de medida indireta apresentam boa aceitação para os atletas de futsal, tendo em vista a alta correlação com os testes de medida direta, o baixo custo de sua aplicação e o fornecimento de informações importantes que podem auxiliar na prescrição e no acompanhamento do treinamento.La importância de las cualidades morfo-funcionales en la mejora del rendimiento en los deportes aumentó el interes en el acondicionamiento de los niveles de aptitud física de los atletas. En tanto, hay pocos estudios sobre las variables fisiológicas del futsal disponibles en la literatura mundial. De esta forma, el objetivo del estudio fué verificar la existencia de la correlación entre los tests de medida directa e indirecta del VO2max, en jugadores de futsal. Fueron analizados 13 jugadores de futsal, con edades de entre 18,6 ± 1,9 años, altura igual a 177,1 ± 3,5 cm, peso de 68,5 ± 9,5 kg, índice de masa corporal (IMC) de 21,7 ± 2,3 kg/m². Para la medida directa del VO2max fué utilizado el sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) para mensura indirecta del VO2max fué realizado el test de campo de 3200m. El análisis estatístico fué elaborado a través del test t-Student para las muestras pareadas y por el coeficiente de correlación de Pearson. Los valores de VO2max obtenidos en el test de medida directa no presentaron diferencias significativas en relación a la medida indirecta (62,8 ± 10,1 vs. 58,5 ± 8,5 ml/kg/min, respectivamente). Cuando correlacionamos los valores de VO2max obtenidos en ambos tests, observamos una fuerte correlación (r = 0,72). En conclusión, los tests de medida indirecta presentaron buena aceptación para los atletas de futsal, teniendo en vista la alta correlación con los tests de medida directa, el bajo costo de su aplicación y el apercibimiento de las informaciones importantes que puedem auxiliar la prescrición de el no acompañamiento del entrenamiento.The importance of the morphofunctional qualities to greater efficiency in sports has increased the interest on the improvement on the physical fitness levels of athletes. However, not many studies on the physiological variables of indoor soccer are available in the world scientific literature. Thus, the objective of this work was to verify the existence of correlation between the direct and indirect VO2max measurement tests in indoor soccer players. Thirteen indoor soccer players with age of 18.6 ± 1.9 years, height of 177.1 ± 3.5 cm, weight of 68.5 ± 9.5 kg and body mass index (BMI) of 21.7 ± 2.3 kg/m² were analyzed. For the direct VO2max measurement, the computerized ergospirometric system was used (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) and

Anna Myrna Jaguaribe de Lima; Daniele Vanusca Gomes Silva; Alexandre Oscar Soares de Souza

2005-01-01

178

POSSIBILITIES AND NECESSITIES OF INNOVATION IN TEACHING / Možnosti a potreby inovácií vo vyu?ovaní  

Directory of Open Access Journals (Sweden)

Full Text Available Author deals with actual questions of teaching process and didactics. He indicates the possibilities and the need of changes in the educational process. These changes relate to contentual, but also processual aspects of educational process dominated by innovative educational methods and approaches. This report presents a complex view of innovation in education.Príspevok sa zaoberá aktuálnymi otázkami vyu?ovacieho procesu a didaktiky a nazna?uje možnosti a potreby zmien vo výchovno-vzdelávacom procese. Zmeny sa týkajú nielen obsahových, ale aj procesuálnych stránok vyu?ovacieho procesu, v ktorom musia prevláda? inovatívne vyu?ovacie metódy a prístupy. Príspevok podáva komplexnejší poh?ad na inovácie vo vyu?ovaní.

Petlák Erich

2008-01-01

179

[Effect of 4 weeks of training on the limit time at VO2 max].  

UK PubMed Central (United Kingdom)

The purpose of this study was to examine the effect of 4 weeks training in running on the time spent at VO2max (tlim VO2max). Eight athletes carried out, before and after an aerobic training, an incremental and five exhaustive tests at 90, 95, 100, 115% vVO2max and at the critical power at VO2max (CV'; slope of the linear relation between the tlim VO2max and the distance limit at VO2max). This training did not significantly improve VO2max (p = 0.17) or tlim VO2max (p = 0.72). However, the "tlim VO2max-intensity" curve was shifted toward the right, meaning that the athlete had to run at a higher intensity after training to obtain the same tlim VO2max. Tlim VO2max at CV' before training was significantly higher than tlim VO2max at 90, 95, 100, and 115% vVO2max (p < 0.05). This training increased CV' in absolute value (13.9 +/- 1.3 vs. 14.9 +/- 1.2 km.h-1, p < 0.05; n = 6) but not in relative value (86 +/- 4 vs. 86 +/- 5% vVO2max; p = 0.9). In conclusion, in spite of the shift of the "tlim VO2max-intensity" curve, tlim VO2max was not significantly increased by this training. Furthermore, CV' allowed subjects to spend the longest time of exercise at VO2max during a continuous exercise with constant speed, but CV', expressed in % vVO2max, did not improve with this training.

Heubert R; Bocquet V; Koralsztein JP; Billat V

2003-10-01

180

[Effect of 4 weeks of training on the limit time at VO2 max].  

Science.gov (United States)

The purpose of this study was to examine the effect of 4 weeks training in running on the time spent at VO2max (tlim VO2max). Eight athletes carried out, before and after an aerobic training, an incremental and five exhaustive tests at 90, 95, 100, 115% vVO2max and at the critical power at VO2max (CV'; slope of the linear relation between the tlim VO2max and the distance limit at VO2max). This training did not significantly improve VO2max (p = 0.17) or tlim VO2max (p = 0.72). However, the "tlim VO2max-intensity" curve was shifted toward the right, meaning that the athlete had to run at a higher intensity after training to obtain the same tlim VO2max. Tlim VO2max at CV' before training was significantly higher than tlim VO2max at 90, 95, 100, and 115% vVO2max (p < 0.05). This training increased CV' in absolute value (13.9 +/- 1.3 vs. 14.9 +/- 1.2 km.h-1, p < 0.05; n = 6) but not in relative value (86 +/- 4 vs. 86 +/- 5% vVO2max; p = 0.9). In conclusion, in spite of the shift of the "tlim VO2max-intensity" curve, tlim VO2max was not significantly increased by this training. Furthermore, CV' allowed subjects to spend the longest time of exercise at VO2max during a continuous exercise with constant speed, but CV', expressed in % vVO2max, did not improve with this training. PMID:14710523

Heubert, Richard; Bocquet, Valéry; Koralsztein, Jean Pierre; Billat, Véronique

2003-10-01

 
 
 
 
181

A VoIP Privacy Mechanism and its Application in VoIP Peering for Voice Service Provider Topology and Identity Hiding  

CERN Document Server

Voice Service Providers (VSPs) participating in VoIP peering frequently want to withhold their identity and related privacy-sensitive information from other parties during the VoIP communication. A number of existing documents on VoIP privacy exist, but most of them focus on end user privacy. By summarizing and extending existing work, we present a unified privacy mechanism for both VoIP users and service providers. We also show a case study on how VSPs can use this mechanism for identity and topology hiding in VoIP peering.

Shen, Charles

2008-01-01

182

Proposal of Secure VoIP System Using Attribute Certificate  

Science.gov (United States)

VoIP is a service that changes the analogue audio signal into a digital signal and then transfers the audio information to the users after configuring it as a packet; and it has an advantage of lower price than the existing voice call service and better extensibility. However, VoIP service has a system structure that, compared to the existing PSTN (Public Switched Telephone Network), has poor call quality and is vulnerable in the security aspect. To make up these problems, TLS service was introduced to enhance the security. In practical system, however, since QoS problem occurs, it is necessary to develop the VoIP security system that can satisfy QoS at the same time in the security aspect. In this paper, a user authentication VoIP system that can provide a service according to the security and the user through providing a differential service according to the approach of the users by adding AA server at the step of configuring the existing VoIP session is suggested. It was found that the proposed system of this study provides a quicker QoS than the TLS-added system at a similar level of security. Also, it is able to provide a variety of additional services by the different users.

Kim, Jin-Mook; Jeong, Young-Ae; Hong, Seong-Sik

183

Intestinal absorption and secretion of radioactive vanadium (48VO-3) in rats and effect of Al(OH)3  

International Nuclear Information System (INIS)

Sprague-Dawley rats (180-300 g) were fasted overnight and gavaged with 5 ?mol Na3VO4 in 1.0 ml 0.9% NaCl containing 1 ?Ci 48V. Control animals (n = 12) simultaneously received 1.0 ml diluent and experimental animals (n = 12) received 1 ml Al(OH)3. Diluent and Al(OH)3 were then given daily for 4 d. Urine and feces were collected separately each day. In control animals total 48V recovery (stool and urine) over 4 d was 86.6 +/- 2.4% of the administered dose. Although Al(OH)3 insignificantly increased total 48V recovery (93.6 +/- 3.2%), it markedly increased excretion of 48V in the stool as compared to the urine (control:stool, 69.1 +/- 1.8%; urine, 12.5 +/- 1.3%; Al(OH)3:stool, 85.7 +/- 1.5%; urine, 7.9 +/- 1.8%). Animals were then sacrificed and tissue uptake of tracer measured. The pattern of unexcreted 48V in tissues of both groups was kidney > bone > liver > intestine > muscle, but the tissue levels were uniformly higher in controls than in Al(OH)3-treated animals. The ability of Al(OH)3 to remove endogenous VO-3 was also examined. 48V was injected ip (n = 20). Half of the animals received diluent and half received 1.0 ml Al(OH)3 by gavage daily for 4 d. There were no differences in the pattern of 48V tissue distribution and excretion. It is concluded that Al(OH)3 may prevent tissue accumulation of VO-3 from dietary sources by reducing intestinal VO-3 absorption

1982-01-01

184

Abundancia y biomasa de macroinvertebrados edáficos en la temporada lluviosa, en tres usos de la tierra, en los Andes colombianos  

Directory of Open Access Journals (Sweden)

Full Text Available COMPENDIO los usos evaluados fueron pastizal, cafetal y bosque secundario (Vereda Villa del Rosario, Aprox. 3º 33' 16â€? Latitud Norte y 76º 36' 01â€? Longitud Oeste, altitud 1.500 a 1.820m., precipitación 960 a 1.050 mm/año, 19.8 a 21.2º C) con la metodología TSBF. Se implementaron tres monolitos por uso y cada uno se subdividió en cuatro estratos (hojarasca, 0-10 cm, 10-20 cm, y 20-30 cm), las variables densidad y biomasa por parcela y estrato se examinaron a través de ANOVAS y Post-Anovas. En abundancia la supremacía fue de hormigas (25584 ejemplares), miriápodos (4808 ejemplares) y lombrices (1984 ejemplares), la diferencia significativa la marcaron los miriápodos (F=4.84, P=0.014) asociados con bosque y cafetal con sombrío. En biomasa los grupos más importantes fueron miriápodos (701.05 g m-2, 58.71%), lombrices (90.64 g m-2; 7.59%), chisas (27.07 g m-2; 2.26%) hor­migas (20.90 g m-2; 1.75%) y arañas (15.71 g m-2 ; 1.31%), con diferencias significativas en hormigas (F=4.17, P=0.024) y arañas (F=3.43, P=0.4024); También hubo diferencias estadísticas significativas en la densidad y biomasa de macroinvertebrados y los estratos de los monolitos, los resultados indican que estos organismos expresan en su población y biomasa respuestas ambientales asociadas más con la estructura del agroecosistema que con la variación química, física o microbiológica del hábitat; se recomienda discriminar taxonómicamente los grupos funcionales y ampliar los muestreos a la temporada seca. Palabras clave: uso del suelo, macroinvertebrados edáficos, densidad, abundancia, agroecosistemas, Andes colombianos. ABSTRACT Abundance and biomass of soil macroinvertabrates during the rainy season in three land use systems in the Colombian Andes. Using the TSBF methodology, three land use systems—pastures, coffee plantation, and secondary forest— were evaluated in the rural community of Villa del Rosario, located in the municipality of Cali, Valle del Cauca, Colombia . This community is located at approximately 3º 33' 16 N and 76º 36' 01 W, with an altitude of 1.500-1.820 m above sea level, an annual precipitation of 960-1.050 mm, and temperatures ranging from 19.8 to 21.2º C. Three monoliths were used per land use system, each one subdivided into four strata (fallen leaves and 0-10 cm, 10-20 cm, and 20-30 cm in depth). The variables for density and biomass per plot and stratum were submitted to ANOVA and post-ANOVA comparison. Among macroin­vertebrates found, ants outnumbered the others by far with 25.584 individuals, followed by myriapods with 4808 individuals, and earthworms with 1984. A significant difference was found in the case of myriapods (F=4.84, P=0.014) in association with forest and coffee plantation under shade. In terms of biomass, the most important groups found were myriapods (701.05 g m-2, 58.71%), earthworms (90.64 g m-2, 7.59%), grubs (27.07 g m-2, 2.26%), ants (20.90 g m-2, 1.75%), and spiders (15.71 g m-2, 1.31%). Significant differences were found in the case of ants (F=4.17, P=0.024) and spiders (F=3.43, P=0.4024). Significant statistical differences were also found for density and biomass of macroinvertebrates and monolith strata. Results indicated that the environmental response of these organisms in terms of population and biomass is more associated to agroecosystem structure than to chemical, physical, or microbiological variation of the habitat. Functional groups should be taxonomically differentiated and samplings should be extended to the dry season. Key words: land use, soil macroinvertebrates, density, agroecosystems, Colombian Andes, biomass.

Pardo Luis C

2006-01-01

185

A Dust Extinction Web Service in the VO Framework  

Science.gov (United States)

Extragalactic objects observed through telescopes are dimmed and reddened via dust from within our own galaxy. Currently, the Virtual Observatory (VO) has registered dozens of catalogs, including the SDSS, the 2dFGRS, and GOODS, among others (see www.openskyquery.net for example), and not all of these data offer Galactic extinction corrected magnitudes. Likewise, some users will wish to tailor reddening corrections to their own needs. As part of an excercise at the NVO Summer School held in 2004, we have created a callable dust extinction web service that utilizes the Schlegel et al. (1998) extinction maps. In this talk, we go through a step-by-step procedure to design and implement a simple web service in the VO framework. Likewise, we show how our service can be utilized in currently available VO Tools.

Miller, C. J.; Krughoff, K. S.; Ho, T. K.

2004-12-01

186

The sustainability of VO2max: effect of decreasing the workload.  

UK PubMed Central (United Kingdom)

The study examined the maintenance of VO(2max) using VO(2max) as the controlling variable instead of power. Therefore, ten subjects performed three exhaustive cycling exercise bouts: (1) an incremental test to determine VO(2max) and the minimal power at VO(2max) (PVO(max)), (2) a constant-power test at PVO(max) and (3) a variable-power test (VPT) during which power was varied to control VO(2) at VO(2max). Stroke volume (SV) was measured by impedance in each test and the stroke volume reserve was calculated as the difference between the maximal and the average 5-s SV. Average power during VPT was significantly lower than PVO(max) (238 ± 79 vs. 305 ± 86 W; p < 0.0001). All subjects, regardless of their VO(2max) values and/or their ability to achieve a VO(2max) plateau during incremental test, were able to sustain VO(2max) for a significantly longer time during VPT compared to constant-power test (CPT) (958 ± 368 s vs. 136 ± 81 s; p < 0.0001). Time to exhaustion at VO(2max) during VPT was correlated with the power drop in the first quarter of the time to exhaustion at VO(2max) (r = 0.71; p < 0.02) and with the stroke volume reserve (r = 0.70, p = 0.02) but was not correlated with VO(2max). This protocol, using VO(2max) rather than power as the controlling variable, demonstrates that the maintenance of exercise at VO(2max) can exceed 15 min independent of the VO(2max) value, suggesting that the ability to sustain exercise at VO(2max) has different limiting factors than those related to the VO(2max) value.

Billat V; Petot H; Karp JR; Sarre G; Morton RH; Mille-Hamard L

2013-02-01

187

The sustainability of VO2max: effect of decreasing the workload.  

Science.gov (United States)

The study examined the maintenance of VO(2max) using VO(2max) as the controlling variable instead of power. Therefore, ten subjects performed three exhaustive cycling exercise bouts: (1) an incremental test to determine VO(2max) and the minimal power at VO(2max) (PVO(max)), (2) a constant-power test at PVO(max) and (3) a variable-power test (VPT) during which power was varied to control VO(2) at VO(2max). Stroke volume (SV) was measured by impedance in each test and the stroke volume reserve was calculated as the difference between the maximal and the average 5-s SV. Average power during VPT was significantly lower than PVO(max) (238 ± 79 vs. 305 ± 86 W; p < 0.0001). All subjects, regardless of their VO(2max) values and/or their ability to achieve a VO(2max) plateau during incremental test, were able to sustain VO(2max) for a significantly longer time during VPT compared to constant-power test (CPT) (958 ± 368 s vs. 136 ± 81 s; p < 0.0001). Time to exhaustion at VO(2max) during VPT was correlated with the power drop in the first quarter of the time to exhaustion at VO(2max) (r = 0.71; p < 0.02) and with the stroke volume reserve (r = 0.70, p = 0.02) but was not correlated with VO(2max). This protocol, using VO(2max) rather than power as the controlling variable, demonstrates that the maintenance of exercise at VO(2max) can exceed 15 min independent of the VO(2max) value, suggesting that the ability to sustain exercise at VO(2max) has different limiting factors than those related to the VO(2max) value. PMID:22752344

Billat, Véronique; Petot, Hélène; Karp, Jason R; Sarre, Guillaume; Morton, R Hugh; Mille-Hamard, Laurence

2012-07-03

188

Distribución de biomasa de Barleria lupulina Lindl. en respuesta a tres regímenes de riego Biomass distribution of Barleria lupulina Lindl. in response to three watering regimes  

Directory of Open Access Journals (Sweden)

Full Text Available Barleria lupulina es un planta con propiedades medicinales potenciales, cuya acumulación de fitomasa, a nivel de sus órganos, ha sido poco investigada. Se determinó la distribución de biomasa de B. lupulina Lindl. en respuesta a tres regímenes de riego. Se diseñaron, por triplicado, tres tratamientos de riego: cada 2 (RI), 5 (RII) y 15 (RIII) días. Se realizaron mediciones del contenido relativo de agua (CRA), el potencial hídrico, y determinaciones de área foliar y biomasa seca a los seis meses después de la emergencia de las plántulas. El área foliar disminuyó un 88%, y la biomasa total 60% en estrés más severo (RIII), en concordancia con la disminución en el contenido relativo de agua y el potencial hídrico, pero las inflorescencias y el número de semillas incrementaron. Asimismo, el régimen de riego menos frecuente (RIII) afectó la distribución de asimilados puesto que los valores calculados a través de los índices como: la relación raíz/vástago (R/V), la relación de área foliar (RAF) y el área foliar específica (AFE) disminuyeron con dicho tratamiento. Se concluye que los efectos producidos por la disminución en la disponibilidad de agua comprenden reducción en la biomasa radical, cambios en la distribución de biomasa, variación del área foliar y aumento en las estructuras reproductivas.Barleria lupulina is a vascular plant with potential medicinal properties, which phytomass accumulation at the organ's level, has been poor investigated. Biomass distribution of Barleria lupulina Lindl. in response to three watering regimes was determined. Three treatment, in triplicate, of watering were designed: every 2 (RI), 5 (RII) and 15 (RIII) days. The relative water content (RWC), leaf water potentials, leaf area and dry biomass were measured six months later the emergency of the seedlings. Leaf area decreased 88% and total biomass 60%, with the more severe water stress (RIII), and corresponding with a decrease in RWC and water potential, but inflorescens and seeds were greatest. The less frequent watering regimes (RIII) affected assimilate distribution because the value calculations in: root/shoot (R/S), leaf area ratio (LAR) and specific leaf area (SLA) decreased. We concluded that the effects produced by the reduction in water availability include a decrease in root biomass, changes in biomass distribution, variation in leaf area and increases in reproductive structures.

V Paz; A Vera; A Páez

2003-01-01

189

Conversión hidrotérmica subcrítica de residuos orgánicos y biomasa: Mecanismos de reacción/ Subcritical hydrothermal conversion of organic wastes and biomass: Reaction pathways  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La conversión hidrotérmica es un procedimiento que emula el proceso natural de conversión de la materia orgánica en un biocrudo con propiedades físico-químicas similares a las del petróleo. La transformación artificial de biomasa requiere conocer previamente las rutas de reacción y productos prevalentes. En la conversión de celulosa, el principal componente de la biomasa, se presenta despolimerización por hidrólisis y se obtienen oligosacáridos, los cuales pr (more) esentan deshidratación y condensación retro-aldol, para transformarse en furfurales y ácidos carboxílicos. Otros componentes de la biomasa como lignina, proteínas y ésteres grasos, presentan rutas de reacción en las que coexisten la hidrólisis y la pirólisis. Dada la presencia de carbohidratos en la biomasa, los principales productos de su conversión hidrotérmica subcrítica y de sus residuos serán análogos a los que presenta la celulosa. Dichas sustancias tienen un valor agregado que supera considerablemente los costos de adquisición de la materia prima. Al representar en un gráfico las relaciones molares O/C, H/C de los principales productos de conversión hidrotérmica de biomasa reportados en la literatura, se evidencia que la trayectoria de evolución para los productos de conversión hacia biocrudos se traslapa con la evolución geológica de los combustibles fósiles. Abstract in english Hydrothermal conversion is a procedure which emulates organic matter?s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requires previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis) is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol (more) condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters) present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added-value by far surpassing raw material?s acquisition cost. When the main hydrothermal conversion products? O/C, H/C molar ratios as reported in literature are plotted, an evolutionary trajectory for conversion products appears to be closely or even overlapped with fossil fuels? geological evolution.

Castro Vega, Alejandro Amadeus; Rodríguez Varela, Luis Ignacio; Díaz Velásquez, José de Jesús

2007-04-01

190

Conversión hidrotérmica suscritica de residuos orgánicos y biomasa. Mecanismos de reacción Subcritical hydrothermal conversion of organic wastes and biomass. Reaction pathways  

Directory of Open Access Journals (Sweden)

Full Text Available La conversión hidrotérmica es un procedimiento que emula el proceso natural de conversión de la materia orgánica en un biocrudo con propiedades fisicoquímicas similares a las del petróleo. La transformación artificial de biomasa requiere conocer previamente las rutas de reacción y productos prevalentes. En la conversión de celulosa, el principal componente de la biomasa, se presenta despolimerización por hidrólisis y se obtienen oli- gosacaridos, los cuales presentan deshidratación y condensación retro-aldol, para transformarse en furfurales y ácidos carboxIlicos. Otros componentes de la biomasa como lignina, proteInas y ésteres grasos, presentan rutas de reacción en las que coexisten la hidrólisis y la pirólisis. Dada la presencia de carbohidratos en la biomasa, los principales productos de su conversión hidrotérmica subcrItica y de sus residuos seran analogos a los que presenta la celulosa. Dichas sustancias tienen un valor agregado que supera considerablemente los costos de adquisición de la materia prima. Al representar en un grafico las relaciones molares O/C, H/C de los principales productos de conversión hidrotérmica de biomasa reportados en la literatura, se evidencia que la trayectoria de evolución para los productos de conversión hacia biocrudos se traslapa con la evolución geológica de los combustibles fósiles.Hydrothermal conversion is a procedure which emulates organic matter’s natural conversion into bio-crude having physical and chemical properties analogous to petroleum. The artificial transformation of biomass requi- res previous knowledge of the main reaction routes and product availability. The main component of biomass (depolymerisation by hydrolysis) is presented in hydrothermal cellulose conversion, producing oligosaccharides which exhibit dehydration and retro-aldol condensation reactions for transforming into furfurals and carboxylic acids. Other biomass components (such as lignin, proteins, and fat esters) present both hydrolysis and pyrolysis reaction routes. As long as biomass mainly contains carbohydrates, subcritical hydrothermal conversion products and their wastes will be fundamentally analogous to those displaying cellulose. These substances have added- value by far surpassing raw material’s acquisition cost. When the main hydrothermal conversion products’ O/C, H/C molar ratios as reported in literature are plotted, an evolutionary tralectory for conversion products appears to be closely or even overlapped with fossil fuels’ geological evolution.

Castro Vega Alejandro Amadeus; Rodríguez Varela Luis Ignacio; Díaz Velásquez José de Jesús

2007-01-01

191

Biosorption of Pb (II) by Agave tequilana Weber (agave azul) biomass/ Biosorpción de Pb (II) por biomasa de Agave tequilana Weber (agave azul)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este estudio, la biomasa producida de los residuos industriales y el desecho agrícola del Agave tequilana Weber (Agave azul) generados en la producción de tequila, demostró un alto potencial para la remoción de Pb (II) de soluciones acuosas. La capacidad de biosorción de la biomasa de las hojas de Agave azul fue evaluada en experimentos en lote. Estos experimentos incluyeron perfil de pH, dependencia del tiempo y la determinación de la capacidad de adsorción. Lo (more) s experimentos de dependencia del tiempo indicaron que la adsorción de los iones de Pb(II) por la biomasa de Agave azul fue dependiente del tiempo. Las isotermas de Freundlich y Langmuir fueron usadas para describir la biosorción del Pb (II) sobre la biomasa de las hojas del Agave azul a 298 K y un pH de 5.0. El coeficiente de correlación para la isoterma de Freundlich fue más alto que el respectivo coeficiente para la isoterma de Langmuir, indicando que solo el modelo de Freundlich describe los datos obtenidos. La máxima capacidad (K F) fue 105.52 10-2 moles/g para Pb (II). La capacidad de adsorción mostrada por la biomasa del Agave azul fue más alta que el valor promedio de los valores reportados en la literatura. Abstract in english In this study, the biomass produced from the industrial residues and agricultural waste of Agave tequilana Weber (Agave azul) generated in the production of tequila, demonstrated a high potential for Pb (II) removal from aqueous solution. The biosorption capacity of Agave azul leaves biomass was evaluated in batch experiments. These experiments included pH profile, time dependence, and the determination of adsorption capacity. Time profile experiments indicated that the a (more) dsorption of Pb ions by Agave azul biomass was time-dependent. Freundlich and Langmuir isotherms were used to describe the biosorption of Pb (II) onto the Agave azul leaves biomass at 298 K and pH 5.0. The correlation coefficient for the Freundlich isotherm was much higher than the coefficient for the Langmuir isotherm, indicating that only the Freundlich models fits the data. The maximum capacity (K F) was 105.52 10-2 mole/g for Pb (II). The adsorption capacity showed by Agave azul biomass was higher than the average values reported in the literature.

Romero-González, J; Parra-Vargas, F; Cano-Rodríguez, I; Rodríguez, E; Ríos-Arana, J; Fuentes-Hernández, R; Ramírez-Flores, J

2007-12-01

192

Correlação entre as medidas direta e indireta do VO2max em atletas de futsal/ Correlation between direct and indirect VO2max measurements in indoor soccer players/ Correlación entre las medidas directa e indirecta del VO2max en atletas de futsal  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese A importância das qualidades morfofuncionais na melhora do rendimento nos esportes aumentou o interesse no aprimoramento dos níveis de aptidão física dos atletas. No entanto, há poucos estudos sobre as variáveis fisiológicas do futsal disponíveis na literatura científica mundial. Dessa forma, o objetivo deste estudo foi verificar a existência de correlação entre os testes de medida direta e indireta do VO2max, em jogadores de futsal. Foram analisados 13 jogado (more) res de futsal, com idade de 18,6 ± 1,9 anos, altura igual a 177,1 ± 3,5cm, peso de 68,5 ± 9,5kg, índice de massa corporal (IMC) de 21,7 ± 2,3kg/m². Para medida direta do VO2max foi utilizado o sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) e para mensuração indireta do VO2max foi realizado o teste de campo de 3.200m. A análise estatística foi elaborada através do teste t de Student para amostras pareadas e pelo coeficiente de correlação de Pearson. Os valores de VO2max obtidos no teste de medida direta não apresentaram diferenças significativas em relação à medida indireta (62,8 ± 10,1 vs. 58,5 ± 8,5ml/kg/min, respectivamente). Quando correlacionados os valores de VO2max obtidos em ambos os testes, observou-se forte correlação (r = 0,72). Em conclusão, os testes de medida indireta apresentam boa aceitação para os atletas de futsal, tendo em vista a alta correlação com os testes de medida direta, o baixo custo de sua aplicação e o fornecimento de informações importantes que podem auxiliar na prescrição e no acompanhamento do treinamento. Abstract in spanish La importância de las cualidades morfo-funcionales en la mejora del rendimiento en los deportes aumentó el interes en el acondicionamiento de los niveles de aptitud física de los atletas. En tanto, hay pocos estudios sobre las variables fisiológicas del futsal disponibles en la literatura mundial. De esta forma, el objetivo del estudio fué verificar la existencia de la correlación entre los tests de medida directa e indirecta del VO2max, en jugadores de futsal. Fuer (more) on analizados 13 jugadores de futsal, con edades de entre 18,6 ± 1,9 años, altura igual a 177,1 ± 3,5 cm, peso de 68,5 ± 9,5 kg, índice de masa corporal (IMC) de 21,7 ± 2,3 kg/m². Para la medida directa del VO2max fué utilizado el sistema ergoespirométrico computadorizado (VO-2000, Aerosport, Medgraphics, St. Paul, Minnesota) para mensura indirecta del VO2max fué realizado el test de campo de 3200m. El análisis estatístico fué elaborado a través del test t-Student para las muestras pareadas y por el coeficiente de correlación de Pearson. Los valores de VO2max obtenidos en el test de medida directa no presentaron diferencias significativas en relación a la medida indirecta (62,8 ± 10,1 vs. 58,5 ± 8,5 ml/kg/min, respectivamente). Cuando correlacionamos los valores de VO2max obtenidos en ambos tests, observamos una fuerte correlación (r = 0,72). En conclusión, los tests de medida indirecta presentaron buena aceptación para los atletas de futsal, teniendo en vista la alta correlación con los tests de medida directa, el bajo costo de su aplicación y el apercibimiento de las informaciones importantes que puedem auxiliar la prescrición de el no acompañamiento del entrenamiento. Abstract in english The importance of the morphofunctional qualities to greater efficiency in sports has increased the interest on the improvement on the physical fitness levels of athletes. However, not many studies on the physiological variables of indoor soccer are available in the world scientific literature. Thus, the objective of this work was to verify the existence of correlation between the direct and indirect VO2max measurement tests in indoor soccer players. Thirteen indoor soccer (more) players with age of 18.6 ± 1.9 years, height of 177.1 ± 3.5 cm, weight of 68.5 ± 9.5 kg and body mass index (BMI) of 21.7 ± 2.3 kg/m² were analyzed. For the direct VO2max measurement, the computerized erg

Lima, Anna Myrna Jaguaribe de; Silva, Daniele Vanusca Gomes; Souza, Alexandre Oscar Soares de

2005-06-01

193

Infrared-sensitive electrochromic device based on VO2  

Science.gov (United States)

The field-effect transistor (FET) provides an electrical switching function of current flowing through a channel surface by external voltage. Here, we report on a field-effect device that enables electrical switching of optical transmittance as well as conventional electrical current. We investigated optical properties of vanadium dioxide (VO2) thin film under the presence of electric field generated at the interface between VO2 and ionic liquid in a FET geometry, and found that the device exhibits clear electrochromic effect with large ON/OFF contrast only in the infrared region, potentially beneficial for energy-saving smart window applications as a voltage-tunable transparent heat-cutting filter.

Nakano, M.; Shibuya, K.; Ogawa, N.; Hatano, T.; Kawasaki, M.; Iwasa, Y.; Tokura, Y.

2013-10-01

194

Metodología de diseño e implementación de soluciones voIP  

Directory of Open Access Journals (Sweden)

Full Text Available El presente documento ilustra metodológicamente el diseño y la implementación de una solución VoIP, la cual integra la planta análoga (PBX) con el modulo de PBX del Elastix (IP-PBX), por medio de un Gateway de VoIP. Con el producto de esta investigación, desarrollada por el grupo INTEGRA, se permite el uso de nuevos servicios enfocados en el óptimo uso de las redes (telefonía y datos) usando servicios adicionales, como son: servidor de fax, servidor de mensajería instantánea, control y reporte detallado de llamadas, grabaciones y servicios adicionales como la recepción de fax y buzón de mensajes al correo electrónico como archivos adjuntos.

Wilson A. Bulla B.; Rafael A. Fino S.

2012-01-01

195

Lightweight security mechanism for PSTN-VoIP cooperation  

CERN Multimedia

In this paper we describe a new, lightweight security mechanism for PSTN-VoIP cooperation that is based on two information hiding techniques: digital watermarking and steganography. Proposed scheme is especially suitable for PSTN-IP-PSTN (toll-by-passing) scenario which nowadays is very popular application of IP Telephony systems. With the use of this mechanism we authenticate end-to-end transmitted voice between PSTN users. Additionally we improve IP part traffic security (both media stream and VoIP signalling messages). Exemplary scenario is presented for SIP signalling protocol along with SIP-T extension and H.248/Megaco protocol.

Mazurczyk, W; Mazurczyk, Wojciech; Kotulski, Zbigniew

2006-01-01

196

Efecto de la poda en el rendimiento de biomasa de 20 accesiones de especies arbóreas Effect of pruning on the biomass yield of 20 accessions of tree species  

Directory of Open Access Journals (Sweden)

Full Text Available Se evaluó el comportamiento de 20 accesiones de arbóreas ante la poda, durante cinco años, para lo cual se utilizó un diseño de bloques al azar con ocho repeticiones. Se determinó la biomasa comestible, la biomasa leñosa y la biomasa total, así como la composición bromatológica y el número de rebrotes. En el período lluvioso manifestaron un mejor comportamiento, en cuanto al rendimiento de biomasa, L. macrophylla CIAT-17240 y L. leucocephala CIAT-17498 (3,02 y 3,15 kg de MS/árbol como promedio). El número de rebrotes osciló entre 7 y 24 y la de mejor resultado fue L. leucocephala CIAT-17498 (24 rebrotes por planta). Sin embargo, en el período poco lluvioso la producción de biomasa comestible fluctuó entre 0,10 y 1,25 kg de MS/árbol, y se destacó de nuevo L. leucocephala CIAT-17498. Un comportamiento similar al del período lluvioso se constató en los indicadores restantes. Se concluye que los mejores resultados en cuanto a la producción de biomasa comestible se encontraron en el período lluvioso; se destacó L. leucocephala CIAT-17498 en este indicador y en el número de rebrotes para ambas épocas del año. Los contenidos de materia seca, fibra bruta y proteína bruta de la biomasa comestible de las plantas, tuvieron poca variación por el efecto de la época dentro de la misma especie, tendencia que se comprobó también para los minerales. Las accesiones demostraron ser una importante alternativa para la alimentación de los rumiantes, por sus altos contenidos de proteína bruta.The performance of 20 tree accessions when pruned was evaluated during five years, for which a randomized block design with eight repetitions was used. The edible, ligneous and total biomass, as well as the bromatological composition and number of regrowths were determined. In the rainy season L. macrophylla CIAT-17240 and L. leucocephala CIAT-17498 showed a better performance, regarding biomass yield (3,02 and 3,15 kg DM/tree as average). The number of regrowths varied between 7 and 24 and the best result was observed in L. leucocephala CIAT-17498 (24 regrowths per plant). Nevertheless, in the dry season the edible biomass production fluctuated between 0,10 and 1,25 kg DM/tree, and L. leucocephala CIAT-17498 stood out again. A performance similar to that of the rainy season was observed in the other indicators. The best results regarding edible biomass production were concluded to be found in the rainy season; L. leucocephala CIAT-17498 stood out in this indicator and in the number of regrowths for both seasons. The dry matter, crude fiber and crude protein contents of the edible biomass of the plants, had little variation due to the effect of the season within the same species, a trend that was also observed for minerals. The accessions proved to be an important alternative for feeding ruminants, because of their high contents of crude protein.

Odalys C Toral; J. M Iglesias

2007-01-01

197

DO VIDEOCONFERENCES HAVE PLACE IN BIOLOGY EDUCATION? / Majú videokonferencie miesto vo vyu?ovaní?  

Directory of Open Access Journals (Sweden)

Full Text Available In this article we indicate our research results, where we focused on the possibilities of using videoconferencing in biology education in present conditions at primary and secondary schools. The aim of research was to prepare, realize and archive videoconferences by using accessible peripheral devices and information and communication technologies. Using videoconferencing we were able to realize experiments, that were not possible to implement in school conditions. Within the research we also wanted to recognize the pupils interest in above mentioned form of education and usage of ICT in education.V príspevku približujeme výsledky výskumu zameraného na možnosti využitia videokonferencií vo vyu?ovaní biológie v sú?asných podmienkach základných a stredných škôl. Cie?om výskumu bolo pripravi?, uskuto?ni? a archivova? videokonferencie s využitím dostupných periférnych zariadení a informa?ných a komunika?ných technológií. Prostredníctvom videokonferencie sme realizovali experimenty, ktoré nie je možné uskuto?ni? v podmienkach školskej praxe. V rámci výskumu sme chceli zisti? aj mieru záujmu žiakov o uvedenú formu vyu?ovania a využívanie informa?ných a komunika?ných technológií vo vyu?ovaní.

?ipková Elena; Gálová Tímea; Karol?ík Štefan; Ušáková Katarína; Grašáková Júlia

2009-01-01

198

New refinement of the room-temperature structure of LiCuVO sub 4  

Energy Technology Data Exchange (ETDEWEB)

Lithium copper(II) vanadate, M{sub r}=207.43, orthorhombic, Imma, a=5.662(1), b=5.809(1), c=8.758(2) A, V=288.0(2) A{sup 3}, Z=4, D{sub x}=4.78 Mg m{sup -3}, Mo K{alpha}, {lambda}=0.71069 A, {mu}=10.4 mm{sup -1}, F(000)=348, R=0.040 for 461 unique reflections. The sample was prepared by hydrothermal growth (T=919 K, P=190 MPa, 48 h) of 1.5 g of a powder of LiCuVO{sub 4} in 1.65 cm{sup 3} of 0.1 M NaF aqueous solution. LiCuVO{sub 4} is an orthorhombic distortion of the cubic spinel structure, with V{sup 5+} on tetrahedral sites and Li{sup +} and Cu{sup 2+} distributed in an ordered way on the octahedral sites. This leads to edge-sharing chains of Li{sup +} and Cu{sup 2+} octahedra running along (100) and (010), respectively. (orig.).

Lafontaine, M.A.; Leblanc, M.; Ferey, G. (Le Mans Univ., 72 (France). Lab. de Fluorures)

1989-08-15

199

New refinement of the room-temperature structure of LiCuVO4  

International Nuclear Information System (INIS)

Lithium copper(II) vanadate, Mr=207.43, orthorhombic, Imma, a=5.662(1), b=5.809(1), c=8.758(2) A, V=288.0(2) A3, Z=4, Dx=4.78 Mg m-3, Mo K?, ?=0.71069 A, ?=10.4 mm-1, F(000)=348, R=0.040 for 461 unique reflections. The sample was prepared by hydrothermal growth (T=919 K, P=190 MPa, 48 h) of 1.5 g of a powder of LiCuVO4 in 1.65 cm3 of 0.1 M NaF aqueous solution. LiCuVO4 is an orthorhombic distortion of the cubic spinel structure, with V5+ on tetrahedral sites and Li+ and Cu2+ distributed in an ordered way on the octahedral sites. This leads to edge-sharing chains of Li+ and Cu2+ octahedra running along [100] and [010], respectively. (orig.)

1989-08-15

200

Phonon Softenings and the Mott-spin-Peierls Transition in VO2  

Science.gov (United States)

To explore the driving mechanisms of the metal-insulator transition (MIT) and the structural transition in VO2, we have investigated phonon dispersions of rutile VO2 (R-VO2) in the DFT and the DFT+U (U: Coulomb correlation) band calculations. We have found that the phonon softening instabilities occur in both cases, but the softened phonon mode only in the DFT+U describes properly both the MIT and the structural transition from R-VO2 to monoclinic VO2 (M1-VO2). The present ab-initio phonon dispersion calculations clearly demonstrate that the Coulomb correlation effect plays an essential role of assisting the Peierls transition in R-VO2 and producing the spin-Peierls ground state in M1-VO2.

Kim, Sooran; Kim, Kyoo; Kang, Chang-Jong; Min, B. I.

2013-03-01

 
 
 
 
201

Correlation-assisted phonon softening and the orbital-selective Peierls transition in VO2  

Science.gov (United States)

To explore the driving mechanisms of the metal-insulator transition (MIT) and the structural transition in VO2, we have investigated phonon dispersions of rutile VO2 (R-VO2) in the density functional theory (DFT) and the DFT+U (U: Coulomb correlation) band calculations. We have found that the phonon softening instabilities occur in both cases, but the softened phonon mode only in the DFT+U describes properly both the MIT and the structural transition from R-VO2 to monoclinic VO2 (M1-VO2). The present ab initio phonon dispersion calculations clearly demonstrate that the Coulomb correlation effect plays an essential role of assisting the Peierls transition in R-VO2 and producing the spin-Peierls ground state in M1-VO2.

Kim, Sooran; Kim, Kyoo; Kang, Chang-Jong; Min, B. I.

2013-05-01

202

Reproducibility of maximum aerobic power (VO2max) among soccer players using a modified heck protocol Reprodutibilidade da potência aeróbia máxima (VO2max) em jogadores de futebol utilizando o protocolo de heck modificado  

Directory of Open Access Journals (Sweden)

Full Text Available OBJECTIVE: To determine the degree of reproducibility of maximum oxygen consumption (VO2max) among soccer players, using a modified Heck protocol. METHODS: 2 evaluations with an interval of 15 days between them were performed on 11 male soccer players. All the players were at a high performance level; they were training for an average of 10 hours per week, totaling 5 times a week. When they were evaluated, they were in the middle of the competitive season, playing 1 match per week. The soccer players were evaluated on an ergometric treadmill with velocity increments of 1.2 km.h-1 every 2 minutes and a fixed inclination of 3% during the test. VO2max was measured directly using a breath-by-breath metabolic gas analyzer. RESULTS: The maximum running speed and VO2max attained in the 2 tests were, respectively: (15.6 ± 1.1 vs. 15.7 ± 1.2 km.h-1; [P = .78]) and (54.5 ± 3.9 vs. 55.2 ± 4.4 ml.kg-1.min-1; [P = .88]). There was high and significant correlation of VO2max between the 2 tests with a 15-day interval between them [r = 0.97; P OBJETIVO: Determinar o grau de reprodutibilidade do consumo máximo de oxigênio (VO2max) em jogadores de futebol utilizando o protocolo de Heck modificado. MÉTODOS: Foram avaliados por duas vezes, com intervalo de 15 dias entre os testes, 11 futebolistas masculinos. Todos eram de alto nível, treinavam em média 10 horas por semana subdivididos em treinamentos físicos, técnicos, táticos e jogos competitivos, totalizando cinco vezes por semana e na fase em que foram avaliados se encontravam em pleno período competitivo realizando um jogo por semana. Os futebolistas foram avaliados em esteira ergométrica (1,2 km.h-1) a cada dois minutos e inclinação fixa durante o teste em 3%. O VO2max foi medido diretamente utilizando analisador metabólico de análise de gases expirados respiração-a-respiração. RESULTADOS: A velocidade máxima de corrida e o VO2max atingido nos dois testes foram respectivamente: (15,6 ± 1,1 vs. 15,7 ± 1,2 km.h-1; [p = 0,78]) e (54,5 ± 3,9 vs. 55,2 ± 4,4 ml.kg-1.min-1; [P = 0,88]). Houve correlação significante e alta do VO2max entre os dois testes após 15 dias de intervalo [r = 0,97; P< 0,001]. CONCLUSÃO: O protocolo de Heck modificado foi reprodutível e o intervalo de quinze dias entre os testes ergoespirométricos não foi suficiente para modificar significativamente o VO2max dos jogadores de futebol.

Paulo Roberto Santos-Silva; Alfredo José Fonseca; Anita Weigand de Castro; Júlia Maria D'Andréa Greve; Arnaldo José Hernandez

2007-01-01

203

Computer simulation of the defect pair VPb-VO in PbWO4 crystals  

International Nuclear Information System (INIS)

A computer simulation study has been performed to investigate the defects in PbWO4(PWO). The formation energies of isolated point defects VPb'', VO.. and cluster defect VPb''-VO.. pair have been calculated. It is theoretically demonstrated that the most of VO.. in the as-grown PWO crystal exists in the form of the vacancy pair VPb''-VO.., which plays an important role in the formation and transformation process of light induced color centers in the PWO crystal

2005-01-01

204

Improving Quality of VoIP over WiMAX  

Directory of Open Access Journals (Sweden)

Full Text Available Real-time services such as VoIP are becoming popular and are major revenue earners for network service providers. These services are no longer confined to the wired domain and are being extended over wireless networks. Although some of the existing wireless technologies can support some low-bandwidth applications, the bandwidth demands of many multimedia applications exceed the capacity of these technologies. The IEEE 802.16-based WiMAX promises to be one of the wireless access technologies capable of supporting very high bandwidth applications. In this paper, we exploit the rich set of flexible features offered at the medium access control (MAC) layer of WiMAX for the construction and transmission of MAC protocol data units (MPDUs) for supporting multiple VoIP streams. We discuss the quality of VoIP calls, usually given by R-score, with respect to the delay and loss of packets. We analysis the quality of service (QoS) on long distance data transfer between two locations with VoIP over WiMAX will be performed. Performance of selected parameters will be done using the network simulator, OPNET Modeler 14.5 [1,2].

M.A. Mohamed; F.W. Zaki; R. H. Mosbah

2012-01-01

205

Fabrication and Electrical Properties of Pure VO2 Phase Films  

CERN Multimedia

We have grown VO2 thin films by laser ablation for electronic device applications. In obtaining the thin films of the pure VO2 phase, oxygen partial pressure is a critical parameter because vanadium oxides have several phases with the oxygen concentration. It is found that the pure VO2 films are grown on Al2O3 substrate in the narrow ranges of 55-60 mTorr in an Ar+10% O2 ambient, and that the mixed phase films are synthesized when the deposition pressure slightly deviates from the optimum pressure. The (100) oriented VO2 films undergo an abrupt metal-insulator transition (MIT) with resistance change of an order of 104 at 338K. In the films of mixed phases, the small change of the resistance is observed at the same temperature. The polycrystalline films are grown on SiO2/Si substrate, and undergo a broaden MIT of the resistance. This may be attributed to mixed phases generated in the films because of a coarse interface states. Furthermore, the abrupt MIT and collective current motion appearing in metal are obs...

Chae, B G; Kim, H T; Maeng, S Y; Kang, K Y

2003-01-01

206

Matching of Male and Female Subjects Using VO2 Max.  

Science.gov (United States)

|The increasing use of various VO2 max expressions as test measures is a problem because the magnitude of sex difference varies considerably with each expression. A valid match of male and female test subjects would consider physical activity history and the amount of endurance exercise done in the previous year. (Author/FG)|

Cureton, Kirk J.

1981-01-01

207

Validity of 3 protocols for verifying VO2 max.  

UK PubMed Central (United Kingdom)

The verification bout has emerged as a technique for confirming 'true' VO2 max; however, validity during a single visit is unknown. We evaluated 3 different GXT durations with severe intensity verification bouts. On 3 separate days, in counterbalanced order, 12 recreational-trained men completed short (9±1 min), middle (11±1 min), and long (13±2 min) duration GXTs followed by exhaustive, sine wave verification bouts during the same visit. Intensities for verification were set at speeds equivalent to 2-stages minus end-GXT speed. No differences (p<0.05) in VO2 max (mL/kg/min) were observed between short (49.1), middle (48.2), and long (48.8) protocols. In addition, no differences in verification bout duration occurred between protocols (3±1 min). Validity of VO2 max was strongest for the middle duration protocol (ICC ?=0.97; typical error=1 mL/kg/min; CV=2%). A small, but significantly higher HR (max) (?1-2 bpm) was observed for the long protocol. Maximum respiratory exchange ratios were inconsistent (ICC ? ranged 0.58-0.68). Our findings indicate GXT-verification bout testing during a single visit is a valid means of measuring 'true' VO2 max. The 10 min target for GXT duration was the optimum.

Kirkeberg JM; Dalleck LC; Kamphoff CS; Pettitt RW

2011-04-01

208

Mathematical Representation of VoIP Connection Delay  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The main topic of this article is to define mathematical formulation of VoIP connection delay model. It handles about all partial delay components, the mechanism of their generation, facilities and their mathematical formulation. Thereafter based on mathematical formulation of all partial delay comp...

I. Baronak; M. Halas

209

Covert Channels in SIP for VoIP signalling  

CERN Multimedia

In this paper, we evaluate available steganographic techniques for SIP (Session Initiation Protocol) that can be used for creating covert channels during signaling phase of VoIP (Voice over IP) call. Apart from characterizing existing steganographic methods we provide new insights by introducing new techniques. We also estimate amount of data that can be transferred in signalling messages for typical IP telephony call.

Mazurczyk, Wojciech

2008-01-01

210

Covert Channels in SIP for VoIP Signalling  

Science.gov (United States)

In this paper, we evaluate available steganographic techniques for SIP (Session Initiation Protocol) that can be used for creating covert channels during signaling phase of VoIP (Voice over IP) call. Apart from characterizing existing steganographic methods we provide new insights by introducing new techniques. We also estimate amount of data that can be transferred in signalling messages for typical IP telephony call.

Mazurczyk, Wojciech; Szczypiorski, Krzysztof

211

Advantages of VoIP in the german research network  

UK PubMed Central (United Kingdom)

With the arising of telephony over the internet, loads of institutes start looking at that new technology. They askthemselves for sense and meaningful use. Many questions appeared to be answered first. The first one is about theinteroperability of the end systems. It should be possible to change the vendor and implement the new devices withoutany problems into the existing VoIP infrastructure. These ideas led to first single VoIP labs. To increase the value ofsuch installations, they should be interconnected. Because of the very heterogeneous hardware, which has been used bythe institutes, the construction of a VoIP network has been a project for itself. Several working groups have beenformed in order to examine single questions much closer. Examples are the accounting, the security and the requiredquality of service within the transport network. However, the research work has not finished yet. There are stillunsolved questions about the accounting and the security in such a large VoIP network as it became today. Routingstrategies have to be discussed as well as security questions. Maybe a single institution should start offering IPtelephony as a service for the complete german research network. Currently, it is a distributed group.

Falko Dressler

212

Estimation of VO2 Max: A Comparative Analysis of Five Exercise Tests.  

Science.gov (United States)

|Thirty-eight healthy females measured maximal oxygen uptake (VO2max) on the cycle ergometer and treadmill to compare five exercise tests (run, walk, step, and two tests using heart-rate response on the bicycle ergometer) in predicting VO2max. Results indicate that walk and run tests are satisfactory predictors of VO2max in 30- to 39-year-old…

Zwiren, Linda D.; And Others

1991-01-01

213

Towards Secure SIP Signalling Service for VoIP applications : Performance-related Attacks and Preventions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Current Voice over IP (VoIP) services are regarded less secure than the traditional public switched telephone network (PSTN). This is due to the fact that VoIP services are frequently deployed in an relatively open environment so that VoIP infrastructures can be easily accessed by potential attacker...

Zhang, Ge

214

Simulation of a large scale ATM network with VoIP traffic  

UK PubMed Central (United Kingdom)

IP telephony (Voice over IP -- VoIP) has become animportant driver for packet-based communications. Theimpact of the growing VoIP traffic on communicationnetworks, especially backbone networks cannot beneglected. Telecom service providers must be aware thatVoIP is the newest, fast-growing alternative for voicecommunication.

Balzs Csik

215

PRELIMINARY ANALYSIS OF BIOMASS POTENTIALLY USEFUL FOR PRODUCING BIODIESEL/ ANALISIS PRELIMINAR DE BIOMASA POTENCIALMENTE ÚTIL PARA PRODUCIR BIODIESEL  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Considerando que el biodiesel se está convirtiendo en una solución viable para algunos problemas energéticos y medioambientales, la investigación de materias primas para su producción es un tema de creciente interés. Este estudio presenta los resultados de una investigación dedicada al análisis preliminar de varias especies vegetales (biomasa), potencialmente útiles para producir biodiesel. La zona de bioprospección es una región de la costa pacifica colombiana (more) . Las especies promisorias recolectadas fueron sometidas a diferentes pruebas normalizadas ASTM para definir propiedades que faciliten su evaluación. Algunas de las especies fueron sometidas a un proceso de transesterificación. Adicionalmente, se realiza una comparación entre las propiedades termo-físicas de los biodiesel y las propiedades del diesel comercial. Las pruebas de rendimiento de estos biocombustibles en los motores de encendido por compresión, particularmente la eficiencia, el consumo y la potencia a diferentes RPM del motor, se presentan en este trabajo. Abstract in english Given that biodiesel is emerging as a viable solution for some energy and environmental problems, research on raw materials appropriate for its production is a matter of growing interest. In this study we present the results of research devoted to preliminary analysis on several vegetable (biomass) species potentially useful for producing biodiesel. The bioprospection zone is a region on the Colombian Pacific coast. The candidate species collected underwent different stan (more) dardized ASTM tests in order for us to define properties that facilitate their evaluation. Some of the species underwent a transesterification process. Comparisons between the thermo-physical properties of the biofuels obtained and the properties of commercial diesel were carried out. Also, performance tests for these biofuels were conducted in compression ignition engines, particularly evaluating efficiency, fuel consumption, and potency at different RPMs.

CABRERA CIFUENTES, GERARDO; BURBANO JARAMILLO, JUAN CARLOS; GARCIA MELO, JOSÉ ISIDRO

2011-12-01

216

A new valid and reliable windtrainer VO2max protocol.  

UK PubMed Central (United Kingdom)

AIM: Maximal oxygen uptake (VO(2max)) cycling protocols usually require expensive laboratory ergometers where the athlete is unaccustomed to the cycling position. Recently, we developed a VO(2max) speed-ramped protocol with an indoor cycling simulator (Cateye Windtrainer WT) allowing cyclists to use their own bicycles during the VO(2max) test. The aim of this study was to test the validity of the WT protocol by comparing it with a traditional (TD) resistance-ramped protocol using an electronically braked ergometer. In addition, the retest reliability of the WT protocol was also determined. METHODS: Twenty experienced cyclists randomly completed 6 VO(2max) protocols consisting of one familiarization trial and two tests on the WT and TD protocols. RESULTS: There were minimal differences in maximal oxygen uptake values between protocols (WT 64.1+/-7.1, TD 63.3+/-7.4 mL/kg/min). The variability in the difference of the means between the two protocols was 0.8 mL/kg/min (95% confidence interval CI: -0.26-2.02), the coefficient of variation (CV) was 2.8% (95%CI: 2.2-4.2%) and the interclass correlation was r=0.94 (P<0.01; 95%CI: 0.86-0.98). The intratest difference within the WT protocol was 1.5% (95%CI: -1.9-5%), CV=5.3% (95%CI: 4.1-8%) and the retest correlation was r=0.81 (P<0.01; 95%CI: 0.57-0.92). CONCLUSION: The WT speed-ramped protocol is a valid and reliable method to assess VO(2max).

Dalziel WM; Hannan SM; Watts MC; Coombes JS

2007-09-01

217

Pressure-induced transformations in PrVO4 and SmVO4 and isolation of high-pressure metastable phases.  

Science.gov (United States)

Zircon-type PrVO4 and SmVO4 have been studied by high-pressure Raman spectroscopy up to 17 GPa. The occurrence of phase transitions has been detected when compression exceeds 6 GPa. The transformations are not reversible. Raman spectra of the high-pressure phases show similarities with those expected for a monazite-type phase in PrVO4 and a scheelite-type phase in SmVO4.The high-pressure phases have been also synthesized using a large-volume press and recovered at ambient conditions. X-ray diffraction measurements of the metastable products recovered after decompression confirms the monazite (PrVO4) and scheelite (SmVO4) structures of the high-pressure phases. Based upon optical properties of the reported new polymorphs, novel applications for rare-earth vanadates are proposed, including photocatalytic hydrogen production. PMID:23600563

Errandonea, Daniel; Achary, S Nagabhusan; Pellicer-Porres, Julio; Tyagi, Avesh K

2013-04-19

218

TRENDS IN THE EDUCATIONAL ACHIEVEMENT OF SLOVAK STUDENTS IN PHYSICS IN THE TIMSS STUDY / Trendy vo vzdelávacích výsledkoch žiakov Slovenskej republiky z fyziky vo výskume TIMSS  

Directory of Open Access Journals (Sweden)

Full Text Available Physics is one of the Science topics, which is included to research area in the TIMSS study. The educational achievement in Physics is measured in international comparison. We present the Physics characteristics as the research area based on the content and cognitive dimension. We analyzed the trends in educational achievement between 1995 - 1999 - 2003. The article brings the findings about the overall results, the differences between boys and girls. We publish the comparison on the international level - comparison the Slovak results and ten other countries in the Europe, which had been participating in all cycles of the TIMSS study. We analyzed the student aspiration to education level as one of the factor, what has the influence on educational achievement.Fyzika patrí medzi prírodovedné predmety, ktoré tvoria výskumnú doménu medzinárodnej štúdie TIMSS. V medzinárodnom kontexte sa meria úrove? vzdelávacích výsledkov žiakov z fyziky. V ?lánku uvádzame charakteristiku fyziky ako výskumnej oblasti z poh?adu požiadaviek na hodnotenie vedomostí a zru?ností žiakov pod?a obsahovej a kognitívnej dimenzie. Prezentujeme výsledky analýzy trendov vo vzdelávacích výsledkoch žiakov z fyziky medzi rokmi 1995 – 1999 – 2003 pod?a vybraných aspektov. Uvádzame zistenia o celkových vzdelávacích výsledkoch žiakov z fyziky, o rozdieloch medzi výkonmi chlapcov a diev?at. Prezentujeme komparáciu výsledkov na medzinárodnej úrovni – porovnanie výsledkov žiakov z fyziky na Slovensku s výsledkami žiakov v desiatich vybraných európskych krajinách, ktoré sa opakovane zú?astnili výskumu TIMSS. Z faktorov pôsobiacich na vzdelávacie výsledky sme analyzovali vplyv ašpirácie žiakov k vzdelaniu, typu školy a najvyššie dosiahnutého vzdelania rodi?ov.

Kuraj Jozef; Kurajová Stopková Janka

2010-01-01

219

Effect of Jahn-Teller interactions on the magnetic properties of DyVO4 and TbVO4  

International Nuclear Information System (INIS)

Temperature dependences (34 and TbVO4 tetragonal monocrystals are experimentally investigated. Bend for dependences M(H), anomalous behaviour of ?(T) in the vicinity of crystal-phase transformations, efficient magnetic anisotropy in basic plane are detected. These peculiarities are shown to be due to correlations of local Jahn-Teller distortions.

1988-01-01

220

Identifying the active site in nitrogen-doped graphene for the VO2+/VO2(+) redox reaction.  

UK PubMed Central (United Kingdom)

Nitrogen-doped graphene sheets (NGS), synthesized by annealing graphite oxide (GO) with urea at 700-1050 °C, were studied as positive electrodes in a vanadium redox flow battery. The NGS, in particular annealed at 900 °C, exhibited excellent catalytic performance in terms of electron transfer (ET) resistance (4.74 ± 0.51 and 7.27 ± 0.42 ? for the anodic process and cathodic process, respectively) and reversibility (?E = 100 mV, Ipa/Ipc = 1.38 at a scan rate of 50 mV s(-1)). Detailed research confirms that not the nitrogen doping level but the nitrogen type in the graphene sheets determines the catalytic activity. Among four types of nitrogen species doped into the graphene lattice including pyridinic-N, pyrrolic-N, quaternary nitrogen, and oxidic-N, quaternary nitrogen is verified as a catalytic active center for the [VO](2+)/[VO2](+) couple reaction. A mechanism is proposed to explain the electrocatalytic performance of NGS for the [VO](2+)/[VO2](+) couple reaction. The possible formation of a N-V transitional bonding state, which facilitates the ET between the outer electrode and reactant ions, is a key step for its high catalytic activity.

Jin J; Fu X; Liu Q; Liu Y; Wei Z; Niu K; Zhang J

2013-06-01

 
 
 
 
221

The ROI of VoIP: Everybody Says VoIP Saves Big Bucks. But Does It?  

Science.gov (United States)

Advocates of Voice over Internet Protocol (VoIP) say it saves money on long distance calls by sending them over the Internet, improves communication by eliminating the Private Branch Exchange (PBX), and offers a host of neat features such as call forwarding, e-mail accessible voicemail, and more. When it comes to measuring the dollars-and-cents…

Villano, Matt

2006-01-01

222

Estimación de biomasa y carbono en dos especies de bosque mesófilo de montaña/ Biomass and carbon assessment in two tree species in a cloudy forest  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La generación de ecuaciones alométricas es importante para determinar la biomasa y el carbono en las especies arbóreas. Esta información es útil en los estudios de cambio climático. En el presente estudio se generaron ecuaciones alométricas para dos especies de importancia ecológica en el bosque mesófilo de montaña: Clethra mexicana DC y Alnus arguta (Schltdl) Spach. Las ecuaciones que se determinaron son de la forma Y= bXk; donde: Y= contenido de biomasa o de c (more) arbono (kg); y X= diámetro normal (DN) en centímetros. Para estimar los valores b y k del modelo para cada especie, se realizó un muestreo de quince árboles de Clethra mexicana y 22 de Alnus arguta. En Clethra mexicana el mayor porcentaje de biomasa 45.2 % se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje estaba 36.3% y 18.6%, respectivamente. Con la biomasa y el DN de los árboles se determinaron los parámetros b y k del modelo propuesto (B= 0.4632 DN1.8168, R²= 0.946). Para Alnus arguta el mayor porcentaje de biomasa (60.6%), se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje presentó 27.4 y 12%, respectivamente. Al igual que el caso anterior con la biomasa y el DN, se obtuvieron los parámetros b y k del modelo propuesto (B= 0.1649 DN2.2755, R²= 0.968). Después de analizar el contenido de carbono en las muestra de cada especie, se ajustaron las ecuaciones para Clethra mexicana C= 22.49DN1.8168, con R²= 0.946, mientras que para Alnus arguta C= 0.0809DN2.2782 con R²= 0.968. Abstract in english The generation of allometric equations is important to determine biomass and carbon in tree species. This information is useful in climate change studies. In this paper, allometric equations were generated for two species of ecological importance in the cloud forest: Clethra mexicana DC and Alnus arguta (Schltdl) Spach. Equations determined are of the form Y= bXk; where: Y= biomass or carbon content (kg); and X= normal diameter (ND) in centimeters. To estimate model value (more) s of b and k for each species, a sampling was performed in fifteen Clethra mexicana and 22 of Alnus arguta trees. In Clethra mexicana the highest percentage of biomass 45.2% was found in the trunk including the stump, while branches and foliage had 36.3% and 18.6% respectively. With the biomass and ND of the tress, b and k parameters were determined from the proposed model (B= 0.4632 DN1.8168, R²= 0.946). For Alnus arguta the highest percentage of biomass (60.6%) was found in the trunk including the stump, while branches and foliage had 27.4 and 12% respectively. Like the previous case with biomass and ND, b and k parameters were obtained from the proposed model (B= 0.1649 DN2.2755, R²= 0.968). After analyzing carbon content in each species samples, equations were adjusted for Clethra mexicana C= 22.49DN1.8168, with R²= 0.946, whereas for Alnus arguta C= 0.0809DN2.2782 with R² = 0.968.

Acosta Mireles, Miguel; Carrillo Anzures, Fernando; Gómez Villegas, Raúl Gilberto

2011-08-01

223

Estimación de biomasa y carbono en dos especies de bosque mesófilo de montaña Biomass and carbon assessment in two tree species in a cloudy forest  

Directory of Open Access Journals (Sweden)

Full Text Available La generación de ecuaciones alométricas es importante para determinar la biomasa y el carbono en las especies arbóreas. Esta información es útil en los estudios de cambio climático. En el presente estudio se generaron ecuaciones alométricas para dos especies de importancia ecológica en el bosque mesófilo de montaña: Clethra mexicana DC y Alnus arguta (Schltdl) Spach. Las ecuaciones que se determinaron son de la forma Y= bXk; donde: Y= contenido de biomasa o de carbono (kg); y X= diámetro normal (DN) en centímetros. Para estimar los valores b y k del modelo para cada especie, se realizó un muestreo de quince árboles de Clethra mexicana y 22 de Alnus arguta. En Clethra mexicana el mayor porcentaje de biomasa 45.2 % se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje estaba 36.3% y 18.6%, respectivamente. Con la biomasa y el DN de los árboles se determinaron los parámetros b y k del modelo propuesto (B= 0.4632 DN1.8168, R²= 0.946). Para Alnus arguta el mayor porcentaje de biomasa (60.6%), se encontró en el fuste incluido el tocón, mientras que en las ramas y el follaje presentó 27.4 y 12%, respectivamente. Al igual que el caso anterior con la biomasa y el DN, se obtuvieron los parámetros b y k del modelo propuesto (B= 0.1649 DN2.2755, R²= 0.968). Después de analizar el contenido de carbono en las muestra de cada especie, se ajustaron las ecuaciones para Clethra mexicana C= 22.49DN1.8168, con R²= 0.946, mientras que para Alnus arguta C= 0.0809DN2.2782 con R²= 0.968.The generation of allometric equations is important to determine biomass and carbon in tree species. This information is useful in climate change studies. In this paper, allometric equations were generated for two species of ecological importance in the cloud forest: Clethra mexicana DC and Alnus arguta (Schltdl) Spach. Equations determined are of the form Y= bXk; where: Y= biomass or carbon content (kg); and X= normal diameter (ND) in centimeters. To estimate model values of b and k for each species, a sampling was performed in fifteen Clethra mexicana and 22 of Alnus arguta trees. In Clethra mexicana the highest percentage of biomass 45.2% was found in the trunk including the stump, while branches and foliage had 36.3% and 18.6% respectively. With the biomass and ND of the tress, b and k parameters were determined from the proposed model (B= 0.4632 DN1.8168, R²= 0.946). For Alnus arguta the highest percentage of biomass (60.6%) was found in the trunk including the stump, while branches and foliage had 27.4 and 12% respectively. Like the previous case with biomass and ND, b and k parameters were obtained from the proposed model (B= 0.1649 DN2.2755, R²= 0.968). After analyzing carbon content in each species samples, equations were adjusted for Clethra mexicana C= 22.49DN1.8168, with R²= 0.946, whereas for Alnus arguta C= 0.0809DN2.2782 with R² = 0.968.

Miguel Acosta Mireles; Fernando Carrillo Anzures; Raúl Gilberto Gómez Villegas

2011-01-01

224

Relative Aerial Biomass Yield of Intercroped Alfalfa with Winter Forage Cereals Rendimiento Relativo de Biomasa Aérea en Intercultivos de Alfalfa con Cereales Forrajeros de Invierno  

Directory of Open Access Journals (Sweden)

Full Text Available In the tropical regions of the world, intercropping is mostly associated with food grain production, whereas it is receiving increased attention in temperate regions as a means of efficient forage production. The aim of this work was to determine the relative yield of aerial biomass in alfalfa or lucerne (Medicago sativa L.) and winter forage cereals intercrops. These were done in eight systems resulting from the combination of species sown at different dates. The biomass was measured in three situations: alfalfa and cereal sole-crop and alfalfa-cereal intercrops, the relative biomass yields were calculated by the relative yield index (RYI). The field experiment was conducted as a bifactorial array in a randomized complete block design of two replicates. The alfalfa-cereal intercrops provided RYI values ranging from 0.71 to 0.83. This showed that it is possible to produce, in the same area, between 71 and 83% of the biomass that both crops would produce in separate ones.En las regiones tropicales del mundo, el intercultivo está asociado con la producción de granos para la alimentación, mientras que en áreas templadas recibe mayor atención como medio de producción eficiente de forraje. El objetivo de este experimento fue determinar el rendimiento relativo de biomasa aérea en intercultivos de alfalfa (Medicago sativa L.) y cereales forrajeros de invierno. Se establecieron ocho sistemas producto de la combinación con especies de cereales con distintas fechas de siembra. Las mediciones de biomasa se realizaron en tres situaciones: monocultivo de alfalfa, monocultivo de cereales e intercultivo de alfalfa-cereal, calculándose el rendimiento relativo del intercultivo (RRI). Se empleó un diseño con arreglo bifactorial y dos repeticiones en bloques completos al azar. Los intercultivos de alfalfa-cereal generaron valores de RRI entre 0,71 y 0,83, lo que indicó que en una misma superficie es posible producir entre el 71 y 83% de la biomasa que ambos cultivos producirían en superficies separadas.

Telmo Pereyra; Héctor Pagliaricci; Alfredo Ohanian

2008-01-01

225

Carbono almacenado en la biomasa aérea de plantaciones de araucaria (Araucaria angustifolia -Bert.- O. Ktze)/ Aboveground carbon stocks in plantations of araucariaç (Araucaria angustifolia -Bert.- O. Ktze)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este trabajo se estima el carbono aéreo almacenado en plantaciones de Araucaria angustifolia (Bert.) O. Ktze de diferentes edades, localizadas en el norte de la provincia de Misiones. Se determina la biomasa aérea por muestreo destructivo de árboles de 1, 2, 3, 6, 20, 30 y 40 años de edad, se ajustan ecuaciones para estimar el peso seco de los restantes árboles de la parcela y se calcula la biomasa y el carbono en la totalidad de la plantación de cada una de las (more) edades. El carbono almacenado en la biomasa aérea es de 0,04; 0,31; 1,3; 21,9; 56,2; 60,5 y 92,2 Mg.ha-1 para las edades de 1, 2, 3, 6, 20, 30 y 40 años respectivamente. Abstract in english This work estimated the aboveground carbon stock in plantations of Araucaria angustifolia -Bert.- O. Ktze of different ages, located in the north of the province of Misiones. The aboveground biomass was determined by destructive sampling of trees of 1, 2, 3, 6, 20, 30 and 40 years of age, equations were adjusted to estimate the dry weight of the remaining trees of the plot and biomass and carbon were calculated in the whole plantation of exemplars of all the ages mentione (more) d. The carbon of the total aboveground biomass is 0,04; 0,31; 1,3; 21,9; 56,2; 60,5 and 92,2 Mg.ha-1 for tree ages 1, 2, 3, 6, 20, 30 and 40, respectively.

Vega, José D; Martiarena, Rodolfo

2010-06-01

226

Estimación de la biomasa foliar de Prosopis flexuosa mediante relaciones alométricas/ Estimation of leaf biomass in Prosopis flexuosa by means of allometric relationships  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La estimación alométrica de la biomasa foliar arbórea es necesaria para determinar la producción primaria y para analizar algunas de las interacciones ecológicas entre los árboles y los demás componentes de la vegetación. El objetivo del trabajo fue ajustar y seleccionar modelos para estimar la biomasa foliar de Prosopis flexuosa a partir de variables dendrométricas. Se apearon seis árboles, se midió su diámetro y se calculó el área de albura de muestras tra (more) nsversales de leño, en cuatro niveles: en los órdenes de ramificación dentro de la copa viva (ramas secundarias, terciarias y cuaternarias agrupadas), en el extremo distal de las ramas primarias y en los extremos distal y basal del fuste. Se recolectaron las hojas correspondientes a cada nivel y se obtuvo el peso seco. El área de albura fue la mejor variable predictora de biomasa foliar, aunque el diámetro tuvo buen ajuste en ramas dentro de la copa viva y en ramas primarias. Los modelos calculados con variables de fuste tuvieron menor ajuste. Se concluye que para la estimación no destructiva de la biomasa foliar de plantas adultas de Prosopis flexuosa es recomendable utilizar el modelo basado en el diámetro distal de las ramas primarias. Abstract in english The estimation of leaf biomass, usually performed by alometric relations, is important for the interpretation of primary production and for the assessment of ecological interactions between trees and the rest of the components in a wood vegetation. The goal for the present work was to adjust and to select allometric models for the estimation of leaf biomass Prosopis flexuosa based on dendrometric variables. Six trees were surveyed. The diameter and sapwood area of transve (more) rsal samples of wood were determined at four different levels: in the orders of ramification within living crown (secondary, tertiary and quaternary grouped branches), at the distal portions of primary branches and in the apical and basal portions of bole. The leaves were collected according to each level and dry mass was obtained. The sapwood area was the best predictor of leaf biomass, although diameter provided accurate estimations within crown and at the distal portions of primary branches. The models based on trunk dimensions were less precise. It is concluded that the obtained regression model based on the diameter of the distal portions of primary branches can be applied for the non-destructive estimation of leaf biomass in Prosopis flexuosa adult trees.

Ledesma, M.; Carranza, C.A.; Balzarini, M.

2010-12-01

227

Estimación de la biomasa foliar de Prosopis flexuosa mediante relaciones alométricas Estimation of leaf biomass in Prosopis flexuosa by means of allometric relationships  

Directory of Open Access Journals (Sweden)

Full Text Available La estimación alométrica de la biomasa foliar arbórea es necesaria para determinar la producción primaria y para analizar algunas de las interacciones ecológicas entre los árboles y los demás componentes de la vegetación. El objetivo del trabajo fue ajustar y seleccionar modelos para estimar la biomasa foliar de Prosopis flexuosa a partir de variables dendrométricas. Se apearon seis árboles, se midió su diámetro y se calculó el área de albura de muestras transversales de leño, en cuatro niveles: en los órdenes de ramificación dentro de la copa viva (ramas secundarias, terciarias y cuaternarias agrupadas), en el extremo distal de las ramas primarias y en los extremos distal y basal del fuste. Se recolectaron las hojas correspondientes a cada nivel y se obtuvo el peso seco. El área de albura fue la mejor variable predictora de biomasa foliar, aunque el diámetro tuvo buen ajuste en ramas dentro de la copa viva y en ramas primarias. Los modelos calculados con variables de fuste tuvieron menor ajuste. Se concluye que para la estimación no destructiva de la biomasa foliar de plantas adultas de Prosopis flexuosa es recomendable utilizar el modelo basado en el diámetro distal de las ramas primarias.The estimation of leaf biomass, usually performed by alometric relations, is important for the interpretation of primary production and for the assessment of ecological interactions between trees and the rest of the components in a wood vegetation. The goal for the present work was to adjust and to select allometric models for the estimation of leaf biomass Prosopis flexuosa based on dendrometric variables. Six trees were surveyed. The diameter and sapwood area of transversal samples of wood were determined at four different levels: in the orders of ramification within living crown (secondary, tertiary and quaternary grouped branches), at the distal portions of primary branches and in the apical and basal portions of bole. The leaves were collected according to each level and dry mass was obtained. The sapwood area was the best predictor of leaf biomass, although diameter provided accurate estimations within crown and at the distal portions of primary branches. The models based on trunk dimensions were less precise. It is concluded that the obtained regression model based on the diameter of the distal portions of primary branches can be applied for the non-destructive estimation of leaf biomass in Prosopis flexuosa adult trees.

M. Ledesma; C.A. Carranza; M. Balzarini

2010-01-01

228

Producción de biomasa de la microalga Scenedesmus sp. utilizando aguas residuales de pescadería Biomass production of microalga Scenedesmus sp. with wastewater from fishery  

Directory of Open Access Journals (Sweden)

Full Text Available Las microalgas representan una alternativa para el tratamiento de aguas residuales por su capacidad de remoción de nutrientes y alto valor comercial de la biomasa producida. Se evaluó el crecimiento, remoción de nutrientes y materia orgánica de la microalga Scenedesmus sp. en aguas residuales derivadas de restos de pescadería. Se utilizaron cultivos discontinuos en tanques a cielo abierto con 150L, aireación constante y en condiciones no controladas de fotoperiodo y temperatura. Se evaluó el crecimiento de la microalga mediante recuento celular, peso seco y contenido de pigmentos, realizando la recolección de la misma en fase estacionaria mediante sedimentación natural, y efectuando análisis fisicoquímicos a la biomasa secada al sol. La microalga creció en agua residual a cielo abierto, reportando eficiencias de remoción de 94,44% (23,80mg/L) para nitrógeno amoniacal, de 77,54% (7,04mg/L) para fosfatos y de 35,59% (26,09mg/L) para materia orgánica. La biomasa seca resultó ser un componente de alto contenido proteico (24,41%), fibroso (10,04%), con niveles de grasa (2,47%) y minerales (23,52%) adecuados para complementar la nutrición animal. Estos resultados demostraron que Scenedesmus puede ser utilizada para el tratamiento de aguas residuales con la producción de una biomasa de valor agregado.The microalgae represent an alternative for the treatment of wastewater for his capacity of removal of nutrients and high commercial value of produced biomass. There was evaluated the growth, removal of nutrients and organic matter of Microalgae Scenedesmus sp. in wastewater derived from remains of fish. Discontinuous cultures were in use in tanks to sky opened with 150L, constant aeration and in conditions no controlled of photoperiod and temperature. The growth of microalgae we evaluated by means of cell counting, dry weight and content of pigments, realizing the compilation of the same one in stationary phase by means of natural sedimentation, and effecting physicochemical analyses to the biomass dried to the sun. The microalgae grew in wastewater to opened sky, reporting efficiencies of removal of 94.44% (23.80 mg/L) for ammonia nitrogen, 77.54% (7.04 mg/L) for phosphates and 35.59 % (26.09 mg/L) for organic matter. The dry biomass recollected was a component of high contained protein (24,41%), fibrous (10,04%), with levels of fats (2,47%) and mineral (23,52%) adapted to complement the animal nutrition. These results showed that Scenedesmus can be used for the treatment of wastewater by production of a biomass of added value.

Charity E Andrade R; Alexandra L Vera B; Carmen H Cárdenas L; Ever D Morales A

2009-01-01

229

"Tailored" Submaximal Step Test for VO2max Prediction in Healthy Older Adults.  

UK PubMed Central (United Kingdom)

We developed and validated a "tailored" version of the Astrand-Rhyming step test (tA-R) and a new equation for VO2max prediction in older adults (OA). 60 subjects (age 68±4, 30 M, 30 F) performed our tA-R step test (5-min, 30-cm step, tailored stepping rate) and an incremental cycling test to exhaustion. VO2max was: i) predicted using the standard A-R equation (predictedVO2max); ii) predicted based on our new multiple linear equation (equationVO2max); iii) directly measured by incremental cycling test (directVO2max). Agreement among values of VO2max was evaluated by Bland-Altman analysis. predictedVO2max was not significantly different from dirrectVO2max yet with relatively large imprecision. equationVO2max allowed more precise as well as accurate predictions of VO2max compared to standard A-R prediction. Our "tailored" version of the Astrand-Rhyming step test and our new prediction equation appear suitable for a rapid (5-min), safe (submaximal), accurate and precise VO2max prediction in healthy OA.

Pogliaghi S; Bellotti C; Paterson DH

2013-05-01

230

Research on optical property of phase transition PcNi/VO2 films  

International Nuclear Information System (INIS)

Highly oriented VO2 thin films were deposited on sapphire substrate and PcNi thin films were spin coated onto VO2 thin films. The microstructure of VO2 thin films were studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated. It was found that the mid-infrared transmittance of the complex films from 1.5 to 5.5 ?m wavelength was raised with PcNi film coating. The thermochromism of PcNi/VO2 films was not changed compared with VO2 films and the transition temperature was same to that of VO2.

1300-01-00

231

Research on optical property of phase transition PcNi/VO{sub 2} films  

Energy Technology Data Exchange (ETDEWEB)

Highly oriented VO{sub 2} thin films were deposited on sapphire substrate and PcNi thin films were spin coated onto VO{sub 2} thin films. The microstructure of VO{sub 2} thin films were studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO{sub 2} multilayer-films were investigated. It was found that the mid-infrared transmittance of the complex films from 1.5 to 5.5 {mu}m wavelength was raised with PcNi film coating. The thermochromism of PcNi/VO{sub 2} films was not changed compared with VO{sub 2} films and the transition temperature was same to that of VO{sub 2}.

Yuan, H.T. [Department of Physics, Changchun University of Science and Technology, Changchun 130022 (China) and Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)]. E-mail: laogun505@sina.com; Feng, K.C. [Department of Physics, Changchun University of Science and Technology, Changchun 130022 (China); Wang, X.J. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); He, C.J. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Li, D.H. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Nie, Y.X. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China); Feng, K.A. [Institute of Physics, Chinese Academy of Science, Beijing 100080 (China)

2005-04-30

232

Research on optical property of phase transition PcNi/VO2 films  

Science.gov (United States)

Highly oriented VO2 thin films were deposited on sapphire substrate and PcNi thin films were spin coated onto VO2 thin films. The microstructure of VO2 thin films were studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated. It was found that the mid-infrared transmittance of the complex films from 1.5 to 5.5 ?m wavelength was raised with PcNi film coating. The thermochromism of PcNi/VO2 films was not changed compared with VO2 films and the transition temperature was same to that of VO2.

Yuan, H. T.; Feng, K. C.; Wang, X. J.; He, C. J.; Li, D. H.; Nie, Y. X.; Feng, K. A.

2005-04-01

233

Structural and thermal studies on Pu(VO3)4  

International Nuclear Information System (INIS)

An hitherto unknown metavanadate of plutonium with composition Pu(VO3)4 was synthesized by heating appropriate amounts of pre-dried PuO2 and V2O5 at 640 deg C for 48 h. The brownish product obtained was characterized by Rietveld refinement of powder XRD data and thermogravimetric analysis. Structural analyses revealed that, Pu(VO3)4 crystallizes in tetragonal (space group: I41/a) lattice with unit cell parameters: a = 8.4582(3) and c = 28.683(2) and Z = 8. The crystal structure of Pu(VO3)4 is isostructural to Th(VO3)4 and Np(VO3)4. TG curve of Pu(VO3)4 did not show any weight change up to 1000 deg C. DTA peaks at 665 and 575 deg C correspond to the melting and crystallization of Pu(VO3)4. (author)

2011-01-01

234

Porous peanut-like Bi2O3-BiVO4 composites with heterojunctions: one-step synthesis and their photocatalytic properties.  

Science.gov (United States)

For the first time, porous peanut-like Bi(2)O(3)-BiVO(4) composites with heterojunctions have been synthesized by a one-step mixed solvothermal method with the assistance of a l-lysine template. A mixture of ethylene glycol (EG) and H(2)O (volume ratio of EG-H(2)O = 3:1) is used as the solvent. Unlike the traditional methods, no concentrated HNO(3) and/or NaOH are involved in diluting Bi and V sources in the adopted approach. The as-synthesized peanut-like samples are rough and porous on the surface and to some extent are interior-hollow. The degradation of methylene blue (MB) is employed to evaluate the photocatalytic activity of the Bi(2)O(3)-BiVO(4) composite. It is observed that the composite performs much better than Bi(2)O(3) and BiVO(4), plausibly due to heterojunctions formed between Bi(2)O(3) and BiVO(4). To investigate the relationship between structure and performance, the as-synthesized samples are characterized by XRD, XPS, SEM, TEM (HRTEM), UV-vis DRS, PL and nitrogen adsorption-desorption methods. Additionally, a possible growth mechanism of this hollow peanut-like structure and the separation process of photogenerated electron-hole pairs on the heterojunctions have been discussed. PMID:22751937

Chen, Lang; Zhang, Qiang; Huang, Rui; Yin, Shuang-Feng; Luo, Sheng-Lian; Au, Chak-Tong

2012-07-02

235

Porous peanut-like Bi2O3-BiVO4 composites with heterojunctions: one-step synthesis and their photocatalytic properties.  

UK PubMed Central (United Kingdom)

For the first time, porous peanut-like Bi(2)O(3)-BiVO(4) composites with heterojunctions have been synthesized by a one-step mixed solvothermal method with the assistance of a l-lysine template. A mixture of ethylene glycol (EG) and H(2)O (volume ratio of EG-H(2)O = 3:1) is used as the solvent. Unlike the traditional methods, no concentrated HNO(3) and/or NaOH are involved in diluting Bi and V sources in the adopted approach. The as-synthesized peanut-like samples are rough and porous on the surface and to some extent are interior-hollow. The degradation of methylene blue (MB) is employed to evaluate the photocatalytic activity of the Bi(2)O(3)-BiVO(4) composite. It is observed that the composite performs much better than Bi(2)O(3) and BiVO(4), plausibly due to heterojunctions formed between Bi(2)O(3) and BiVO(4). To investigate the relationship between structure and performance, the as-synthesized samples are characterized by XRD, XPS, SEM, TEM (HRTEM), UV-vis DRS, PL and nitrogen adsorption-desorption methods. Additionally, a possible growth mechanism of this hollow peanut-like structure and the separation process of photogenerated electron-hole pairs on the heterojunctions have been discussed.

Chen L; Zhang Q; Huang R; Yin SF; Luo SL; Au CT

2012-08-01

236

Un modelo simple para describir la dinámica de la biomasa del camarón nailon Heterocarpus reedi en Coquimbo, Chile/ A simple model for describing the biomass dynamics of the nylon shrimp Heterocarpus reedi at Coquimbo, Chile  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish RESUMEN. Entre septiembre de 1997 y agosto de 2000 se realizó un seguimiento diario de la dinámica espacial y temporal de la CPUE (ton·lance-1) de camarón nailon por parte de la flota arrastrera con puerto base en Coquimbo. Se construyó un modelo de remoción de biomasa modificado para explicar las variaciones temporales de la CPUE basado en los conceptos de abundancia (biomasa total poblacional) y disponibilidad (biomasa que puede ser potencialmente capturada). Amba (more) s cantidades fueron calculadas por ecuaciones, cuyas diferencias (positivas o negativas) indicaron los cambios en la disponibilidad de la biomasa a través del tiempo y el reclutamiento (magnitud y temporalidad). El modelo modificado indicó dos períodos anuales de distinta longitud en la disponibilidad de biomasa al arte de pesca. También indicó una tasa de reducción más acelerada para la biomasa que para la CPUE. Los resultados pueden influir en la determinación de la época óptima para la realización de las evaluaciones directas del recurso con fines de determinar cuotas de captura Abstract in english A daily record of space/time dynamics was carried out on CPUE (ton·trawl-1) for the nylon shrimp trawl fishery based at Coquimbo, Chile, between September 1997 and August 2000. A modified biomass depletion model was constructed to analyze the temporal variations in CPUE based on the concepts of abundance (total population biomass) and availability (potential biomass capture). Both quantities were calculated by equations whose differences (positive and negative) indicated (more) the changes in availability of biomass over time, as well as recruitmernt (magnitude and seasonality). The modified model suggested there were two periods annually, of different lengths, and different biomasses available with the fishing gear. The model also indicated a more rapid rate of reduction in biomass than did the CPUE. The results could influence the determination of the best season for carrying out direct resource evaluations aimed at determining catch quotas

Pérez, Eduardo P.

2005-11-01

237

Phase transition dynamics in high-pressure VO2  

Science.gov (United States)

Vanadium dioxide VO2 is a prototypical strongly correlated material which presents an insulator-metal transition at both ambient and high pressures. We use synchrotron X-ray diffraction combined with a diamond anvil cell to determine the pressure-temperature phase diagram of VO2. We also use ultrafast coherent phonon spectroscopy to study its phase transition dynamics at high pressure. We find that, in contrast with ambient pressure experiments where strong photoexcitation promptly changes the lattice potential symmetry, at pressures as high as P=11 GPa the coherent phonons are still observed upon the photo-driven phase transition to the metallic state. The mechanism of the phase transition dynamics will be discussed.

Hsieh, Wen-Pin; Trigo, Mariano; Zhao, Zhao; Reis, David A.; Mao, Wendy L.

2013-03-01

238

VO2 thermochromic smart window for energy savings and generation.  

UK PubMed Central (United Kingdom)

The ability to achieve energy saving in architectures and optimal solar energy utilisation affects the sustainable development of the human race. Traditional smart windows and solar cells cannot be combined into one device for energy saving and electricity generation. A VO2 film can respond to the environmental temperature to intelligently regulate infrared transmittance while maintaining visible transparency, and can be applied as a thermochromic smart window. Herein, we report for the first time a novel VO2-based smart window that partially utilises light scattering to solar cells around the glass panel for electricity generation. This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner.

Zhou J; Gao Y; Zhang Z; Luo H; Cao C; Chen Z; Dai L; Liu X

2013-01-01

239

VO2: a two-fluid incoherent metal?  

CERN Multimedia

We present {\\it ab initio} LDA+DMFT results for the many-particle density of states of $VO_{2}$ on the metallic side of the strongly first-order ($T$-driven) insulator-metal transition. In strong contrast to LDA predictions, there is {\\it no} remnant of even correlated Fermi liquid behavior in the correlated metal. Excellent quantitative agreement with published photoemission and X-ray absorption experiments is found in the metallic phase. We argue that the absence of FL-quasiparticles provides a natural explanation for the bad-metallic transport for $T > 340 K$. Based on this agreement, we propose that the I-M transition in $VO_{2}$ is an orbital-selective Mott transition, and point out the relevance of orbital resolved one-electron and optical spectroscopy to resolve this outstanding issue.

Laad, M S; Müller-Hartmann, E

2004-01-01

240

VO2 thermochromic smart window for energy savings and generation.  

Science.gov (United States)

The ability to achieve energy saving in architectures and optimal solar energy utilisation affects the sustainable development of the human race. Traditional smart windows and solar cells cannot be combined into one device for energy saving and electricity generation. A VO2 film can respond to the environmental temperature to intelligently regulate infrared transmittance while maintaining visible transparency, and can be applied as a thermochromic smart window. Herein, we report for the first time a novel VO2-based smart window that partially utilises light scattering to solar cells around the glass panel for electricity generation. This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner. PMID:24157625

Zhou, Jiadong; Gao, Yanfeng; Zhang, Zongtao; Luo, Hongjie; Cao, Chuanxiang; Chen, Zhang; Dai, Lei; Liu, Xinling

2013-10-24

 
 
 
 
241

Low-Temperature Raman Spectra of YbVO4  

International Nuclear Information System (INIS)

This paper reports on the spectroscopic study of YbVO4 in the range 10-300 K. All the Raman phonons were properly assigned. Temperature-dependent Raman spectra showed no anomalous changes, which indicate that neither structural phase transition nor strong electron-phonon coupling occur, at least within this temperature range. This result is sharp contrast to those of YbPO4 where strong mixing of the upper crystal-field states ?6 and ?7 with an Eg3 phonon at room-temperature occurs. A possible explanation for the absence of electron-phonon coupling in YbVO4 is the occurrence of the ?6 state at energy higher than the Eg3 phonon, unlike the coincidence of ?6 and Eg3 energies in YbPO4.

2007-11-20

242

VO2 thermochromic smart window for energy savings and generation  

Science.gov (United States)

The ability to achieve energy saving in architectures and optimal solar energy utilisation affects the sustainable development of the human race. Traditional smart windows and solar cells cannot be combined into one device for energy saving and electricity generation. A VO2 film can respond to the environmental temperature to intelligently regulate infrared transmittance while maintaining visible transparency, and can be applied as a thermochromic smart window. Herein, we report for the first time a novel VO2-based smart window that partially utilises light scattering to solar cells around the glass panel for electricity generation. This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner.

Zhou, Jiadong; Gao, Yanfeng; Zhang, Zongtao; Luo, Hongjie; Cao, Chuanxiang; Chen, Zhang; Dai, Lei; Liu, Xinling

2013-01-01

243

Bandwidth-Conserving Multicast VoIP Teleconference System  

Directory of Open Access Journals (Sweden)

Full Text Available Teleconferencing is an essential feature in any business telephone system. A teleconference allows associates to engage in a group discussion by conducting a virtual meeting while remaining at geographically dispersed locations. Teleconferencing increases productivity while reducing travel costs and saving travel time. In a VoIP telephone system, we face the significant challenge of providing a teleconference feature that can support a large-scale teleconference without using excessive bandwidth. This paper presents a new, bandwidth-efficient way of implementing a real-time VoIP teleconference system. This new method provides all of the features that existing teleconference systems provide, but this new approach consumes considerably less data bandwidth than existing systems require. The new system allows a network with a given capacity to accommodate almost double the number of conference participants that an existing system would allow.

Teck-Kuen Chua; David C. Pheanis

2008-01-01

244

CAN WE CONFIDENTLY STUDY VO2 KINETICS IN YOUNG PEOPLE?  

Directory of Open Access Journals (Sweden)

Full Text Available The study of VO2 kinetics offers the potential to non-invasively examine the cardiorespiratory and metabolic response to dynamic exercise and limitations to every day physical activity. Its non-invasive nature makes it hugely attractive for use with young people, both healthy and those with disease, and yet the literature, whilst growing with respect to adults, remains confined to a cluster of studies with these special populations. It is most likely that this is partly due to the methodological difficulties involved in studying VO2 kinetics in young people which are not present, or present to a lesser degree, with adults. This article reviews these methodological issues, and explains the main procedures that might be used to overcome them

Samantha G. Fawkner; Neil Armstrong

2007-01-01

245

Assessment of VoIP Quality over Internet Backbones  

UK PubMed Central (United Kingdom)

As the Internet evolves into a ubiquitous communication infrastructure and provides various services including telephony, it will be expected to stand up to the toll quality standards set by traditional telephone companies. Our objective in this paper is to assess to what extent today's Internet is meeting this expectation. Our assessment is based on delay and loss measurements taken over wide-area backbone networks, considers realistic VoIP scenarios and uses quality measures appropriate for voice. Our findings indicate that although voice services can be adequately provided by some ISPs, a significant number of paths lead to poor performance even for excellent VoIP end-systems. This makes a strong case for special handling of voice traffic on those paths. Even on the good paths, rare loss events can occasionally cause perceptible degradation of voice quality. Finally, the appropriate choice of the playout buffer scheme for each path was found to be of critical importance for the perceived quality.

Athina P. Markopoulou; Fouad A. Tobagi; Mansour J. Karam

246

VoIP over WMN: Effect of packet aggregation  

Directory of Open Access Journals (Sweden)

Full Text Available VoIP services are getting more and more popular day by day. In order to meet the users demand for such services irrespective of users location requires wide area wireless coverage .To this extent,wireless mesh networks have been considered as practical and inexpensive solution .In order to improve the performance of VoIP services, techniques like packet aggregation are done . This paper focuses on finding the effect of packet aggregation on various parameters like aggregation delay, end to end delay and MOS etc. Results obtained through simulations done on Qualnet Simulator concludes that packet aggregation is justified upto a certain extent only as after that most of the users get dissatisfied.

Khyati Marwah,; Dr. Gurpal Singh

2011-01-01

247

Assessment of VoIP Quality over Internet  

UK PubMed Central (United Kingdom)

As the Internet evolves into a ubiquitous communication infrastructureand provides various services including telephony, it will be expectedto stand up to the toll quality standards set by traditional telephonecompanies. Our objective in this paper is to assess to what extent today'sInternet is meeting this expectation. Our assessment is based on delay andloss measurements taken over wide-area backbone networks, considers realisticVoIP scenarios and uses quality measures appropriate for voice. Ourfindings indicate that although voice services can be adequately provided bysome ISPs, a significant number of paths lead to poor performance even forexcellent VoIP end-systems. This makes a strong case for special handlingof voice traffic on those paths. Even on the good paths, rare loss events canoccasionally cause perceptible degradation of voice quality. Finally, the appropriatechoice of the playout buffer scheme for each path was found to beof critical importance for the perceived quality.

Athina P. Markopoulou; Fouad A. Tobagi; Mansour J. Karam

248

Assessment of VoIP Quality over Internet Backbones  

UK PubMed Central (United Kingdom)

As the Internet evolves into a ubiquitous communication infrastructureand provides various services including telephony, it will be expectedto stand up to the toll quality standards set by traditional telephonecompanies. Our objective in this paper is to assess to what extent today'sInternet is meeting this expectation. Our assessment is based on delay andloss measurements taken over wide-area backbone networks, considers realisticVoIP scenarios and uses quality measures appropriate for voice. Ourfindings indicate that although voice services can be adequately provided bysome ISPs, a significant number of paths lead to poor performance even forexcellent VoIP end-systems. This makes a strong case for special handlingof voice traffic on those paths. Even on the good paths, rare loss events canoccasionally cause perceptible degradation of voice quality. Finally, the appropriatechoice of the playout buffer scheme for each path was found to beof critical importance for the perceived quality.

Athina P. Markopoulou; Fouad A. Tobagi; Mansour J. Karam

249

Validade de equações de predição em estimar o VO2max de brasileiros jovens a partir do desempenho em corrida de 1.600m Predictive equations validity in estimating the VO2max of young Brazilians from performance in a 1600 m run  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste estudo foi analisar a validade da equação proposta por Cureton et al. (1995) "VO2peak = -8.41 (MRW) + 0.34 (MRW)2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" em estimar o VO2max de brasileiros jovens a partir de um teste de 1.600 metros, e sugerir uma equação de predição que seja específica para essa população. Participaram do estudo 30 homens fisicamente ativos (23 ± 3,1anos; 74,8 ± 5,8kg; 1,78 ± 0,05m; 49,8 ± 6,5mL.kg-¹.min-1) que foram submetidos a um teste incremental máximo (TI) em esteira e um teste de desempenho em corrida de 1.600 metros. Os indivíduos foram divididos em dois grupos: G1 - para gerar uma equação de predição específica para VO2max de brasileiros jovens e G2 - para aplicar ambas as equações a fim de analisar suas validades. Diferenças estatisticamente significativas foram observadas entre o VO2max determinado diretamente no TI (50,1 ± 7,1mL.kg-¹.min-¹) e os valores de VO2max obtidos pela equação proposta por Cureton et al. (44,2 ± 6,5mL.kg-¹.min-¹) com baixa correlação entre elas (r = 0,21). A relação entre VO2max e velocidade em corrida de 1.600m obtidos no G1 resultou na seguinte equação de predição: (VO2max = 0,177 * 1.600Vm(m.min-1) + 8,101). Quando essa nova equação foi aplicada nos participantes do G2, o VO2max predito (50,1 ± 7,2mL.kg-¹.min-¹) não diferiu do VO2max determinado diretamente (50,1 ± 7,1mL.kg-¹.min-¹) com alta correlação entre eles (r = 0,81). Assim, concluímos que a equação de Cureton et al. (1995), elaborada a partir de resultados de amostra norte-americana, subestimou o VO2max de brasileiros jovens e fisicamente ativos. Por outro lado, a equação proposta no presente estudo se mostrou válida para estimar o VO2max através do teste de desempenho de 1.600 metros para a população estudada.The aim of the present study was to analyze the validity of predictive equation proposed by Cureton et al. (1995) for VO2peak = -8.41 (MRW) + 0.34 (MRW) 2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" on estimating the VO2max of young Brazilians from a 1600-m running performance, and to suggest a predictive equation specific for this population. 30 physically active young men (23±3.1age; 74.8±5.8kg; 1.78±0.05m; 49.8±6.5mL.kg-¹.min-1) who were submitted to an incremental exercise test (IT) on treadmill until exhaustion with gas analysis participated in this study. Subjects also performed a 1600-m running track test as fast as possible. The volunteers were randomly sorted in two groups: G1 - to generate a specific predictive equation for VO2max, and G2 - to apply both predictive equations (actual and from Cureton et al.) to evaluate their validity on estimating VO2max in a Brazilian population sample. Significant differences were observed between VO2max directly identified on IT through gas analysis (50.1±7.1 mL.kg-¹.min-¹) in relation to the results obtained by the predictive equation proposed by Cureton et al. (1995) (44.2±6.5mL.kg-¹.min-¹) with a weak relationship between them (r = 0.21). The relationship between the VO2max on IT and the running velocity on 1600-m as obtained for G1 resulted in the following predictive equation: (VO2max = 0.177*1600Vm(m.min-1) + 8,101). When this new equation was applied on the participants of G2, the predicted VO2max (50.1±7.2mL.kg-¹.min-¹) did not differ from VO2max determined directly on IT (50.1±7.1mL.kg-¹.min-¹) with a high correlation between them (r = 0.81). Thus, it was concluded that the Cureton et al. predictive equation developed with a North Americanpopulation sample as grounding, underestimated the VO2max of physically active young Brazilians. On the other hand, the predictive equation proposed on the present study was considered valid for this purpose through the 1600-m running performance for our participants.

Jeeser Alves de Almeida; Carmen S. G. Campbell; Emerson Pardono; Rafael da Costa Sotero; Guilherme Magalhães; Herbert Gustavo Simões

2010-01-01

250

Validade de equações de predição em estimar o VO2max de brasileiros jovens a partir do desempenho em corrida de 1.600m/ Predictive equations validity in estimating the VO2max of young Brazilians from performance in a 1600 m run  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O objetivo deste estudo foi analisar a validade da equação proposta por Cureton et al. (1995) "VO2peak = -8.41 (MRW) + 0.34 (MRW)2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" em estimar o VO2max de brasileiros jovens a partir de um teste de 1.600 metros, e sugerir uma equação de predição que seja específica para essa população. Participaram do estudo 30 homens fisicamente ativos (23 ± 3,1anos; 74,8 ± 5,8kg; 1,78 ± 0,05m; 49,8 ± 6,5mL.kg-¹.min-1) que foram su (more) bmetidos a um teste incremental máximo (TI) em esteira e um teste de desempenho em corrida de 1.600 metros. Os indivíduos foram divididos em dois grupos: G1 - para gerar uma equação de predição específica para VO2max de brasileiros jovens e G2 - para aplicar ambas as equações a fim de analisar suas validades. Diferenças estatisticamente significativas foram observadas entre o VO2max determinado diretamente no TI (50,1 ± 7,1mL.kg-¹.min-¹) e os valores de VO2max obtidos pela equação proposta por Cureton et al. (44,2 ± 6,5mL.kg-¹.min-¹) com baixa correlação entre elas (r = 0,21). A relação entre VO2max e velocidade em corrida de 1.600m obtidos no G1 resultou na seguinte equação de predição: (VO2max = 0,177 * 1.600Vm(m.min-1) + 8,101). Quando essa nova equação foi aplicada nos participantes do G2, o VO2max predito (50,1 ± 7,2mL.kg-¹.min-¹) não diferiu do VO2max determinado diretamente (50,1 ± 7,1mL.kg-¹.min-¹) com alta correlação entre eles (r = 0,81). Assim, concluímos que a equação de Cureton et al. (1995), elaborada a partir de resultados de amostra norte-americana, subestimou o VO2max de brasileiros jovens e fisicamente ativos. Por outro lado, a equação proposta no presente estudo se mostrou válida para estimar o VO2max através do teste de desempenho de 1.600 metros para a população estudada. Abstract in english The aim of the present study was to analyze the validity of predictive equation proposed by Cureton et al. (1995) for VO2peak = -8.41 (MRW) + 0.34 (MRW) 2 + 0.21 (Age x Gender) -0.84 (BMI) + 108.94" on estimating the VO2max of young Brazilians from a 1600-m running performance, and to suggest a predictive equation specific for this population. 30 physically active young men (23±3.1age; 74.8±5.8kg; 1.78±0.05m; 49.8±6.5mL.kg-¹.min-1) who were submitted to an incrementa (more) l exercise test (IT) on treadmill until exhaustion with gas analysis participated in this study. Subjects also performed a 1600-m running track test as fast as possible. The volunteers were randomly sorted in two groups: G1 - to generate a specific predictive equation for VO2max, and G2 - to apply both predictive equations (actual and from Cureton et al.) to evaluate their validity on estimating VO2max in a Brazilian population sample. Significant differences were observed between VO2max directly identified on IT through gas analysis (50.1±7.1 mL.kg-¹.min-¹) in relation to the results obtained by the predictive equation proposed by Cureton et al. (1995) (44.2±6.5mL.kg-¹.min-¹) with a weak relationship between them (r = 0.21). The relationship between the VO2max on IT and the running velocity on 1600-m as obtained for G1 resulted in the following predictive equation: (VO2max = 0.177*1600Vm(m.min-1) + 8,101). When this new equation was applied on the participants of G2, the predicted VO2max (50.1±7.2mL.kg-¹.min-¹) did not differ from VO2max determined directly on IT (50.1±7.1mL.kg-¹.min-¹) with a high correlation between them (r = 0.81). Thus, it was concluded that the Cureton et al. predictive equation developed with a North Americanpopulation sample as grounding, underestimated the VO2max of physically active young Brazilians. On the other hand, the predictive equation proposed on the present study was considered valid for this purpose through the 1600-m running performance for our participants.

Almeida, Jeeser Alves de; Campbell, Carmen S. G.; Pardono, Emerson; Sotero, Rafael da Costa; Magalhães, Guilherme; Simões, Herbert Gustavo

2010-02-01

251

Implementation of Cloud Computing into VoIP  

Directory of Open Access Journals (Sweden)

Full Text Available This article defines Cloud Computing and highlights key concepts, the benefits of using virtualization, its weaknesses and ways of combining it with classical VoIP technologies applied to large scale businesses. The analysis takes into consideration management strategies and resources for better customer orientation and risk management all for sustaining the Service Level Agreement (SLA). An important issue in cloud computing can be security and for this reason there are several security solution presented.

Floriana GEREA

2012-01-01

252

Accuracy of peak VO2 assessments in career firefighters  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Sudden cardiac death is the leading cause of on-duty death in United States firefighters. Accurately assessing cardiopulmonary capacity is critical to preventing, or reducing, cardiovascular events in this population. Methods A total of 83 male firefighters performed Wellness-Fitness Initiative (WFI) maximal exercise treadmill tests and direct peak VO2 assessments to volitional fatigue. Of the 83, 63 completed WFI sub-maximal exercise treadmill tests for comparison to directly measured peak VO2 and historical estimations. Results Maximal heart rates were overestimated by the traditional 220-age equation by about 5 beats per minute (p 2 was overestimated by the WFI maximal exercise treadmill and the historical WFI sub-maximal estimation by ~ 1MET and ~ 2 METs, respectively (p 2 when compared to directly measured peak VO2. Conclusion Accurate assessment of cardiopulmonary capacity is critical in determining appropriate duty assignments, and identification of potential cardiovascular problems, for firefighters. Estimation of cardiopulmonary fitness improves using the revised 2008 WFI sub-maximal equation.

Drew-Nord Dana C; Myers Jonathan; Nord Stephen R; Oka Roberta K; Hong OiSaeng; Froelicher Erika S

2011-01-01

253

VoSeq: a voucher and DNA sequence web application.  

UK PubMed Central (United Kingdom)

There is an ever growing number of molecular phylogenetic studies published, due to, in part, the advent of new techniques that allow cheap and quick DNA sequencing. Hence, the demand for relational databases with which to manage and annotate the amassing DNA sequences, genes, voucher specimens and associated biological data is increasing. In addition, a user-friendly interface is necessary for easy integration and management of the data stored in the database back-end. Available databases allow management of a wide variety of biological data. However, most database systems are not specifically constructed with the aim of being an organizational tool for researchers working in phylogenetic inference. We here report a new software facilitating easy management of voucher and sequence data, consisting of a relational database as back-end for a graphic user interface accessed via a web browser. The application, VoSeq, includes tools for creating molecular datasets of DNA or amino acid sequences ready to be used in commonly used phylogenetic software such as RAxML, TNT, MrBayes and PAUP, as well as for creating tables ready for publishing. It also has inbuilt BLAST capabilities against all DNA sequences stored in VoSeq as well as sequences in NCBI GenBank. By using mash-ups and calls to web services, VoSeq allows easy integration with public services such as Yahoo! Maps, Flickr, Encyclopedia of Life (EOL) and GBIF (by generating data-dumps that can be processed with GBIF's Integrated Publishing Toolkit).

Peña C; Malm T

2012-01-01

254

CyberSKA Radio Imaging Metadata and VO Compliance Engineering  

Science.gov (United States)

The CyberSKA project has written a specification for the metadata encapsulation of radio astronomy data products pursuant to insertion into the VO-compliant Common Archive Observation Model (CAOM) database hosted by the Canadian Astronomy Data Centre (CADC). This specification accommodates radio FITS Image and UV Visibility data, as well as pure CASA Tables Imaging and Visibility Measurement Sets. To extract and engineer radio metadata, we have authored two software packages: metaData (v0.5.0) and mddb (v1.3). Together, these Python packages can convert all the above stated data format types into concise FITS-like header files, engineer the metadata to conform to the CAOM data model, and then insert these engineered data into the CADC database, which subsequently becomes published through the Canadian Virtual Observatory. The metaData and mddb packages have, for the first time, published ALMA imaging data on VO services. Our ongoing work aims to integrate visibility data from ALMA and the SKA into VO services and to enable user-submitted radio data to move seamlessly into the Virtual Observatory.

Anderson, K. R.; Rosolowsky, E.; Dowler, P.

2013-10-01

255

RELATIONSHIP BETWEEN %HEART RATE RESERVE AND %VO2 RESERVE DURING ELLIPTICAL CROSSTRAINER EXERCISE  

Directory of Open Access Journals (Sweden)

Full Text Available The primary purpose of the study was to determine the relationships between %HRR vs. %VO2R and %HRR vs. %VO2max during maximal elliptical crosstrainer (ECT) exercise. A secondary aim was to compare the %HRR vs. %VO2R and %HRR vs. %VO2max relationships between maximal ECT and treadmill (TM) exercise. Adult subjects (n = 48) completed a maximal exercise test on the ECT, with a subgroup (N = 24) also performing a maximal exercise test on the TM. Continuous HR and VO2 data were analyzed via linear regression to determine y-intercept and slope values for %HRR vs. %VO2R and %HRR vs. %VO2max. Student t-tests were used to determine whether the mean y-intercept and slope values differed from the line of identity (y-intercept = 0, slope = 1). For each group, both the y-intercept and slope for %HRR vs. %VO2R fit the line of identity. Conversely, for all groups both the y-intercept and slope for %HRR vs. %VO2max were significantly different (p 0.05) for either y-intercept (ECT = 0.3 vs. TM = -0.3, p = 0.435) or slope (ECT = 1.01 vs. TM = 1.00, p = 0.079) values. In agreement with previous research on TM and cycle exercise, it was found that %HRR is more closely aligned with %VO2R, rather than %VO2max during ECT exercise. Additionally, it was found that the regressions of %HRR vs. %VO2R and %HRR vs. %VO2max were equivalent between the ECT and TM

Lance C. Dalleck; Len Kravitz

2006-01-01

256

E-LEARNING SOLUTIONS IN EDUCATION OF PEDAGOGIC EMPLOYEES / E-learningové riešenia vo vzdelávaní pedagogických zamestnancov  

Directory of Open Access Journals (Sweden)

Full Text Available According to the requirements on qualitative forms and methods of education, Methodical-pedagogical centre, has prepared a project supporting teaching with use of modern educaton methods with sponzorship from ESF For providing such an extensive project the Methodical-pedagogical centre used e-learning environment. The first part of article emphasizes the importance of teachers education in the new socio-economical conditions. It defines the needs of teachers in the field of using ICT during the education process. It describes forms and methods suitable for gaining new competencies. The second part of the article gives us the information abouth e-learning portal of the project „Functional literacy of teachers in information technologies - use of ICT in subjects". The modules are using the different possibilities of MOODLE interface. Author evaluates the interest of teachers for e-learning and the feedback from lectu-trers. The third part of the article presents first experience of using videoconference in the field of education of teachers, on example of a conference aimed to use of ICT in the work of elementary and high school teachers (in the preparation for teaching and also in the teaching process itself).Na základe potreby zvyšovania k?ú?ových kompetencií pedagogických zamestnancov bol s finan?nou podporou ESF pripravený projekt na podporu vyu?ovania s využitím moderných vyu?ovacích metód. Na zabezpe?enie rozsiahleho projektu v oblasti využívania informa?ných technológií a na zvýšenie efektívnosti vzdelávania pedagogických zamestnancov využilo Metodicko-pedagogické centrum v Tren?íne e-learningové prostredie. Príspevok v prvej ?asti poukazuje na význam vzdelávania u?ite?ov v nových spolo?ensko-eko-nomických podmienkach. Definuje potreby u?ite?ov v oblasti využívania IKT na vyu?ovaní a predstavuje formy a metódy vhodné na získanie nových kompetencií. V druhej ?asti príspevku je predstavený e-learningový portál projektu Funk?ná gramotnos? u?ite?ov v informa?ných technológiách - využitie IKT vo vyu?ovacích predmetoch. Jednotlivé vzdelávacie moduly rozli?nou mierou využívajú možnosti prostredia MOODLE. Autor vyhodnocuje záujem pedagógov o e-learningové vzdelávanie a skúsenosti lektorov zo vzdelávania. V tretej ?asti príspevku sú predstavené prvé skúsenosti využitia videokonferencie v oblasti vzdelávania pedagógov na príklade konferencie zameranej na využívanie informa?ných technológií v práci pedagógov základných a stredných škôl - v príprave na vyu?ovanie i vo vlastnom vyu?ovacom procese.

Jakubeková Miroslava

2008-01-01

257

Efecto del potencial osmótico y contenido de Ca en el medio de cultivo sobre la distribución de Ca2+ Y K+, producción de biomasa y necrosis apical de VID "R110"  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O potencial osmótico, o balanço iônico e as relações nutrimentais dos meios de cultura são determinantes para o crescimento e distribuição dos nutrientes das plantas cultivadas in vitro, entretanto, na maioria dos casos os primeiros não são considerados. Neste estudo, avaliou-se o efeito de diferentes potenciais osmóticos dos sais minerais do meio de cultura (-0,106; -0,113, -0,120; -0,128; -0,143 e -0,157MPa) e concentração de Ca2+ sobre a distribuição de (more) Ca2+, K+ e peso de biomassa seca dos explantes de videira. A concentração iônica foi quantificada com um microscópio eletrônico de barrido de baixo vazio (MEB-LV). O maior potencial osmótico do meio de cultura (-0,106MPa) favoreceu a translocação de Ca2+ e K+ dos talos para as folhas, enquanto o potencial mais negativo (-0,157MPa) permitiu os maiores niveles nos talos. O maior peso de biomassa seca (57mg) e os menores porcentuais de explantes com os sintomas de deficiência de Ca2+ (20%) se obtiveram com o potencial osmótico de -0,106MPa e com a concentração de 1,5mM de Ca2+ no meio de cultura. Abstract in spanish El potencial osmótico, el balance iónico y las relaciones nutricionales del medio de cultivo son determinantes en el crecimiento y distribución de nutrientes de las plantas cultivadas in vitro; sin embargo, en la mayoría de las investigaciones los primeros no se consideran. Se evaluó el efecto de diferentes potenciales osmóticos de las sales (-0,106; -0,113; -0,120; -0,128; -0,143 y -0,157MPa) y del contenido de Ca2+ en el medio de cultivo sobre la distribución de (more) Ca2+ y K+, y el peso de biomasa seca de explantes de vid. La concentración iónica de los explantes se midió con un microscopio electrónico de barrido de bajo vacío (MEB-LV). El mayor potencial osmótico del medio de cultivo (-0,106MPa) favoreció la translocación de Ca2+ y K+ de los tallos hacia las hojas, mientras que, el potencial más negativo (-0,157MPa) permitió que los mayores contenidos se acumularan en los tallos. El mayor peso de biomasa seca (57mg) y los menores porcentajes de explantes con síntomas de deficiencia de Ca2+ (20%) se obtuvieron con el potencial osmótico de -0,106MPa y con concentración de Ca2+ en el medio de cultivo de 1,5mM. Abstract in english The osmotic potential, ionic balance and the nutrient ratios of culture medium are determinant for in vitro propagated plants growth; however, in most investigations, these factors are not considered. The effect of different osmotic potentials (-0.106, -0.113, -0.120, -0.128, -0.143 and -0.157MPa) and Ca2+ contents of culture medium salts on the distribution of Ca2+ and K+, and on dry biomass of explants of grapevine were evaluated. The Ca2+ and K+ concentrations were mea (more) sured with a low vacuum scanning electron microscope (MEB-LV). Ca2+ and K+ translocation from stems to leaves was favored by the higher osmotic potential of culture medium (-0.106MPa), whereas the larger contents of these elements at the base of the stems were found at the most negative osmotic potential (-0.157MPa). The greater dry biomass weight (57mg) and the smaller percentage of explants with Ca2+ deficiency symptoms (20%) were obtained at -0.106MPa, the lower osmotic potential, and 1.5mM Ca2+ in the culture medium.

Molinos da Silva, Christiane; Villegas Monter, Ángel; Sánchez García, Prometeo; Alcántar González, Gabriel; Rodríguez Mendoza, Ma. Nieves; Ruiz Posadas, Lucero del Mar

2004-07-01

258

Facile growth of thermochromic VO2 nanostructures with greatly varied phases and morphologies.  

UK PubMed Central (United Kingdom)

We have successfully and reproducibly synthesized a variety of novel vanadium dioxide (VO2) nanostructures, including metastable monoclinic VO2(B) nanoneedles and nanocorals, orthorhombic VO2(O) nanoparticles, and monoclinic VO2(M) nanofacets by manipulating the aging time of a facile sol-gel approach and the subsequent postannealing conditions. We envision that this previously unreported highly controlled synthesis and the resulting distinct morphologies of VO2 will not only provide a promising route for reliably selecting the phase, size, and morphology of these nanostructures, as well as achieving a fundamental understanding of their unusual temperature-dependent optical transmittance, but also facilitate the synthesis of functional VO2 nanostructures for a number of novel applications.

Wang YT; Chen CH

2013-03-01

259

Synthesis, structure, luminescence properties, quantum chemistry and cytotoxic effects of two vanadium(IV) complexes with polypyrazolylborates, HB(pz)3VO(acac) and HB(3,5-Me2pz)3VO(acac)·CH3CN (pz=pyrazole)  

International Nuclear Information System (INIS)

[en] The reaction of VO(acac)2 (acac = acetylacetonate) with NaHB(pz)3 (pz=pyrazole) or NaHB(3,5-Me2pz)3 in methanol gave vanadium(IV) complexes HB(pz)3VO(acac) (1) or HB(3,5-Me2pz)3VO(acac)CH3CN (2), respectively. The complexes 1 and 2 were characterized by elemental analysis, IR, UV-vis, 1H NMR and X-ray diffraction crystallography methods. Complex 1 crystallizes in space group P21/c, a=7.641(2), b=17.008(4), c=13.362(2) A; ?=92.092(17) deg, V=1735.5(7) A3, Z=4. Complex 2 crystallizes in space group P21/c, a=17.410(13), b=8.076(16), c=19.300(13) A; ?=101.75(5) deg, V=2657(6) A3, Z=4. X-ray structure analyses have shown that the complexes 1 and 2 are monomeric with a similar coordination environment of the vanadium atom. Luminescence properties and cytotoxic effects of the complexes are discussed. On CBRH-7919 cells, the complexes 1 and 2 caused a slight stimulation of growth at low doses (1-10 ?M) and a significant cytotoxic effect at higher doses (100-1000 ?M). The electronic structure and the bonding characters of the two complexes were analyzed with ab initio calculations[ru] ?? ??????? VO(acac)2 (acac = ??????????????-??? ) ? NaHB(pz)3 (pz=???????) ??? NaHB(3,5-Me2pz)3 ? ???????? ???????? ????????? ???????(IV) ?????????????? ??????? HB(pz)3VO(acac) (1) ??? HB(3,5-Me2pz)3VO(acac)CH3CN (2). ??? ????????? ???????????????? ???????? ??????????? ???????, ??- ? ??-?????????????, ??? 1H ? ???????????????????? ???????. ???????? 1 ??????????????? ? ??????????? ????????, ??. ??. P21/c, ? ??????????? ???????????? ??????: a=7.641(2), b=17.008(4), c=13.362(2) A; ?=92.092(17) ????, V=1735.5(7) A3, Z=4. ???????? 2 ??????????????? ????? ? ??????????? ????????, ??. ??. P21/c, a=17.410(13), b=8.076(16), c=19.300(13) A; ?=101.75(5) ????, V=2657(6) A3, Z=4. ????????, ??? ??? ????????? ???????? ??????????? ? ????? ??????????? ??????????????? ????????? ????? ???????. ??????????? ?????????????? ? ??????????????? ???????? ???? ???

2006-01-01

260

Hydrothermal synthesis, dimension evolution and luminescence properties of tetragonal LaVO4:Ln (Ln = Eu3+, Dy3+, Sm3+) nanocrystals.  

UK PubMed Central (United Kingdom)

Well-defined 1D and 3D t-LaVO(4):Ln (Ln = Eu(3+), Dy(3+), Sm(3+)) nanocrystals with regular and uniform shapes were synthesized through a simple hydrothermal route assisted by disodium ethylenediaminetetraacetic acid (Na(2)EDTA). X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), as well as kinetic decay curves were employed to characterize the samples. The results show that the reaction time, pH value of the initial solution, and Na(2)EDTA/La(3+) molar ratio all have an important influence on the dimension and shapes of the final products. By introducing the "splitting mechanism" to the dimension and morphology evolution process from one-dimensional (1D) to three-dimensional (3D) t-LaVO(4) crystals, the nucleation and crystal growth processes were well demonstrated. The Ln(3+) ions doped t-LaVO(4) samples exhibit respective bright red, blue-white and orange luminescence of Eu(3+), Dy(3+), and Sm(3+) under ultraviolet excitation, and have potential application in the fields of colour display, UV laser and biomedicine. The results not only expand the knowledge of the properties of lanthanide orthovanadates luminescence, but also contribute to the principles of the crystal growth and dimension transition of this kind of inorganic material.

He F; Yang P; Wang D; Niu N; Gai S; Li X; Zhang M

2011-11-01

 
 
 
 
261

Effect of Oxide Buffer Layer on the Thermochromic Properties of VO2 Thin Films  

Science.gov (United States)

VO2 thin films were deposited on soda lime glass substrates with ZnO, TiO2, SnO2, and CeO2 thin films applied as buffer layers between the VO2 films and the substrates in order to investigate the effect of buffer layer on the formation and the thermochromic properties of VO2 film. Buffer layers with thicknesses over 50 nm were found to affect the formation of VO2 film, which was confirmed by XRD spectra. By using ZnO, TiO2, and SnO2 buffer layers, monoclinic VO2 (VO2(M)) film was successfully fabricated on soda lime glass at 370 °C. On the contrary, films of VO2(B), which is known to have no phase transition near room temperature, were formed rather than VO2(M) when the film was deposited on CeO2 buffer layer at the same film deposition temperature. The excellent thermochromic properties of the films deposited on ZnO, TiO2, and SnO2 buffer layers were confirmed from the temperature dependence of electrical resistivity from room temperature to 80 °C. Especially, due to the tendency of ZnO thin film to grow with a high degree of preferred orientation on soda lime glass at low temperature, the VO2 film deposited on ZnO buffer layer exhibits the best thermochromic properties compared to those on other buffer layer materials used in this study. These results suggest that deposition of VO2 films on soda lime glass at low temperature with excellent thermochromic properties can be achieved by considering the buffer layer material having structural similarity with VO2. Moreover, the degree of crystallization of buffer layer is also related with that of VO2 film, and thus ZnO can be one of the most effective buffer layer materials.

Koo, Hyun; Xu, Lu; Ko, Kyeong-Eun; Ahn, Seunghyun; Chang, Se-Hong; Park, Chan

2013-10-01

262

VO2 max Characteristics of Male Professional Soccer Players 1989-2012.  

UK PubMed Central (United Kingdom)

PURPOSE: The purpose of this investigation was to quantify VO2 max performance in soccer as a function of performance level, position, age and time of season. In addition, we examined the evolution of VO2 max among professional players over a 23 year period. METHODS: 1545 male soccer players (22 ±4 yr, 76 ±8 kg, 181 ±6 cm) tested VO2 max at the Norwegian Olympic Training Center between 1989 and 2012. RESULTS: No differences in VO2 max were observed among national team players, 1st - 2nd division players and juniors. Midfielders had higher VO2 max than defenders, forwards and goalkeepers (p<0.05). <18 yr players had ~3 % higher VO2 max than 23-26 yr players (p=0.016). The players had 1.6 and 2.1 % lower VO2 max during off season compared to pre season (p=0.046) and in season (p=0.021), respectively. Relative to body mass, VO2 max among the professional players in this study has not improved over time. Professional players tested during time epoch 2006-2012 actually had 3.2 % lower VO2 max than those tested 2000-2006 (p=0.001). CONCLUSIONS: This study provides effect magnitude estimates for the influence of performance level, player position, age, and season time on VO2 max in male elite soccer. Our findings from a robust dataset indicate that VO2 max values ~ 62-64 mL x min-1x kg-1 fulfill the demands for aerobic capacity in male professional soccer and that VO2 max is not a clearly distinguishing variable separating players of different standard.

Tønnessen E; Hem E; Leirstein S; Haugen T; Seiler S

2013-02-01

263

A Case Study in Campus VoIP Deployment: Hype vs. Reality  

UK PubMed Central (United Kingdom)

this paper is to determine whether the installation of Cisco Voice over InternetProtocol (VoIP) equipment at a case study college campus is the right solution at the right time.By analyzing the present products on the market, individual factors at the campus, current VoIPstandards, and information from other VoIP installations we will make recommendationstargeted at assisting other telecommunications planners in similar situations.

Susan Love; Joe Nowalk; Nancy Weiss; Keri Then

264

Comparative Study of VoIP over WiMax and WiFi  

Directory of Open Access Journals (Sweden)

Full Text Available VoIP is a technology in great demand these days. Its interactive nature makes it very appealing for users and today it is one of the most dominant technologies for communication. With the growth over wireless networks the option to have voice communication over wireless has been considered - the choices are VoIP over WiFi or VoIP over WiMax. This paper studies and compares the two options and summarizes the results.

M Atif Qureshi; Arjumand Younus; Muhammad Saeed; Farhan Ahmed Sidiqui; Nasir Touheed; M Shahid Qureshi

2011-01-01

265

Impact of VoIP and QoS on Open and Distance Learning  

Science.gov (United States)

Voice over Internet Protocol (VoIP) is becoming a reality in many organizations. The potential for mobility in voice over wi-fi networks will derive demand for the technology. Wireless VoIP is poised to rival VoIP as an alternative telephony tool. Internet has been used to transport data in the form of packet. In the past, Internet did not support…

Saxena, P. C.; Jasola, Sanjay; Sharma, Ramesh C.

2006-01-01

266

Efeito de diferentes misturas de substratos orgânicos na biomassa e no óleo essencial de Thymus zygis/ Effect of different mixtures of organic substrates on the biomass and essential oil of Thymus zygis  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Neste ensaio avaliou-se o efeito de diferentes misturas de substrato comercial e vermicomposto na produção de biomassa, composição química e rendimento dos óleos essenciais de Thymus zygis. Utilizaram-se 5 substratos resultantes da mistura de um vermicomposto (V) com um substrato orgânico comercial (O), em cinco proporções diferentes (v/v): V100 (100%V); VO75-25 (75%V+25%O); VO50 -50 (50%V+50%O); VO 25-75 (25%V + 75%O) e O100 (100%O). A inclusão do vermicomposto (more) no substrato não melhorou a produção de biomassa. Na modalidade O100 produziu-se mais biomassa, tendo sido na modalidade VO25-75 onde se obteve o valor mais baixo. Na modalidade V100 todas as plantas secaram tendo-se ainda apresentado nesta modalidade o valor mais elevado de pH e de densidade real e inversamente o menor valor de espaço poroso total. Os monoterpenos oxigenados predominaram nos óleos extraídos das plantas nas modalidades O100 e VO25-75, contrariamente ao que se verificou para os monoterpenos não oxigenados tendo estes predominado nas modalidades VO75-25 e VO50-50. A concentração de timol foi elevada nas misturas testadas, em particular na modalidade VO25-75. Abstract in english In this trial we evaluated the effect of different mixtures of organic growing media substratum and vermicompost and their physical properties on biomass, chemical composition and yield of essential oils of Thymus zygis. Five treatments were established based on two types of organic materials (O, commercial growing media, and V, vermicompost). The following proportions were studied (v/v): V100 (100%V); VO75-25 (75%V+25%O); VO50-50 (50%V+50%O); VO 25-75 (25%V+75%O) and O10 (more) 0 (100%O). The inclusion of vermicompost did not improve biomass production. The treatment O100 produced more biomass and the lowest was obtained in VO25-75. On V100 treatment all plants were dead and also have showed the highest pH and particle density and conversely presented the lowest value of total pore space. Oxygenated monoterpenes predominated in the oils extracted from plants in O100 and VO25-75, contrary to what was found for non-oxygenated monoterpenes having these prevailed in VO75-25 and VO50-50. The concentration of thymol was high in the mixtures tested, particularly in VO25-75.

Lourenço, Nelson; Dandlen, Susana A.; Miguel, Maria G.; Figueiredo, Ana; Barroso, José; Pedro, Luis; Coelho, Luísa; Reis, Mário; Correia, Pedro J.

2011-07-01

267

Efeito de diferentes misturas de substratos orgânicos na biomassa e no óleo essencial de Thymus zygis Effect of different mixtures of organic substrates on the biomass and essential oil of Thymus zygis  

Directory of Open Access Journals (Sweden)

Full Text Available Neste ensaio avaliou-se o efeito de diferentes misturas de substrato comercial e vermicomposto na produção de biomassa, composição química e rendimento dos óleos essenciais de Thymus zygis. Utilizaram-se 5 substratos resultantes da mistura de um vermicomposto (V) com um substrato orgânico comercial (O), em cinco proporções diferentes (v/v): V100 (100%V); VO75-25 (75%V+25%O); VO50 -50 (50%V+50%O); VO 25-75 (25%V + 75%O) e O100 (100%O). A inclusão do vermicomposto no substrato não melhorou a produção de biomassa. Na modalidade O100 produziu-se mais biomassa, tendo sido na modalidade VO25-75 onde se obteve o valor mais baixo. Na modalidade V100 todas as plantas secaram tendo-se ainda apresentado nesta modalidade o valor mais elevado de pH e de densidade real e inversamente o menor valor de espaço poroso total. Os monoterpenos oxigenados predominaram nos óleos extraídos das plantas nas modalidades O100 e VO25-75, contrariamente ao que se verificou para os monoterpenos não oxigenados tendo estes predominado nas modalidades VO75-25 e VO50-50. A concentração de timol foi elevada nas misturas testadas, em particular na modalidade VO25-75.In this trial we evaluated the effect of different mixtures of organic growing media substratum and vermicompost and their physical properties on biomass, chemical composition and yield of essential oils of Thymus zygis. Five treatments were established based on two types of organic materials (O, commercial growing media, and V, vermicompost). The following proportions were studied (v/v): V100 (100%V); VO75-25 (75%V+25%O); VO50-50 (50%V+50%O); VO 25-75 (25%V+75%O) and O100 (100%O). The inclusion of vermicompost did not improve biomass production. The treatment O100 produced more biomass and the lowest was obtained in VO25-75. On V100 treatment all plants were dead and also have showed the highest pH and particle density and conversely presented the lowest value of total pore space. Oxygenated monoterpenes predominated in the oils extracted from plants in O100 and VO25-75, contrary to what was found for non-oxygenated monoterpenes having these prevailed in VO75-25 and VO50-50. The concentration of thymol was high in the mixtures tested, particularly in VO25-75.

Nelson Lourenço; Susana A. Dandlen; Maria G. Miguel; Ana Figueiredo; José Barroso; Luis Pedro; Luísa Coelho; Mário Reis; Pedro J. Correia

2011-01-01

268

Aprovechamiento de Biomasa Peletizada en el Sector Ladrillero en Bogotá-Colombia: Análisis Energético y Ambiental Use of Pelleted Biomass in the Brick Industry in Bogota-Colombia: Energy and Environmental Analysis  

Directory of Open Access Journals (Sweden)

Full Text Available En este estudio se compara el desempeño energético y ambiental del uso de combustibles a partir de dos tipos de biomasas peletizadas: residuos de madera, provenientes de podas y residuos de la producción de muebles, principalmente aserrín. La biomasa proveniente de residuos de madera es uno de los materiales más adecuados para utilizar como combustible alternativo. El sector ladrillero tiene una gran demanda energética para sus procesos de secado y cocción y el uso de combustibles alternativos a partir de biomasa permite obtener reducciones importantes en emisiones atmosféricas y no afecta las condiciones técnicas del proceso de producción de ladrillos. La biomasa con mejor desempeño, tanto en las variables energéticas como ambientales evaluadas, fue el aserrín.This study compared the energy and environmental performance of fuels from two types of pelleted biomass: wood waste from pruning and waste from furniture production, mainly sawdust. Wood residues biomass is one of the most suitable materials for using as an alternative fuel. The brick manufacture sector has a high energy demand for its drying and firing processes and the use of alternative fuels from biomass allows significant reductions in emissions and does not affect the technical conditions of the process of brick production. The biomass with better performance was sawdust, which presented the optimum energy and environmental variables.

César A García-Ubaque; Martha L Vaca-Bohórquez; Gabriel F Talero

2013-01-01

269

Aprovechamiento de Biomasa Peletizada en el Sector Ladrillero en Bogotá-Colombia: Análisis Energético y Ambiental/ Use of Pelleted Biomass in the Brick Industry in Bogota-Colombia: Energy and Environmental Analysis  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En este estudio se compara el desempeño energético y ambiental del uso de combustibles a partir de dos tipos de biomasas peletizadas: residuos de madera, provenientes de podas y residuos de la producción de muebles, principalmente aserrín. La biomasa proveniente de residuos de madera es uno de los materiales más adecuados para utilizar como combustible alternativo. El sector ladrillero tiene una gran demanda energética para sus procesos de secado y cocción y el uso (more) de combustibles alternativos a partir de biomasa permite obtener reducciones importantes en emisiones atmosféricas y no afecta las condiciones técnicas del proceso de producción de ladrillos. La biomasa con mejor desempeño, tanto en las variables energéticas como ambientales evaluadas, fue el aserrín. Abstract in english This study compared the energy and environmental performance of fuels from two types of pelleted biomass: wood waste from pruning and waste from furniture production, mainly sawdust. Wood residues biomass is one of the most suitable materials for using as an alternative fuel. The brick manufacture sector has a high energy demand for its drying and firing processes and the use of alternative fuels from biomass allows significant reductions in emissions and does not affect (more) the technical conditions of the process of brick production. The biomass with better performance was sawdust, which presented the optimum energy and environmental variables.

García-Ubaque, César A; Vaca-Bohórquez, Martha L; Talero, Gabriel F

2013-01-01

270

A importância do limiar anaeróbio e do consumo máximo de oxigênio (VO2 máx.) em jogadores de futebol The importance of the anaerobic threshold and maximum oxygen uptake (VO2 PEAK) for soccer players  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo deste estudo foi fazer uma abordagem sobre a importância do limiar anaeróbio (LA) e o consumo máximo de oxigênio (VO2máx.) em jogadores de futebol e comparar os resultados encontrados em nossos futebolistas com os da literatura especializada. Foram avaliados 18 jogadores de futebol profissional, com média de idade de 24 ± 4 anos, peso de 72,5 ± 5,9kg; estatura de 176,5 ± 7,0cm e superfície corpórea de 1,91 ± 0,15m². Todos os atletas foram avaliados após um período de dois meses de treinamentos. Os futebolistas foram submetidos a teste máximo em esteira ergométrica, utilizando-se protocolo escalonado e contínuo. A resposta de freqüência cardíaca (FC) foi registrada por meio de um eletrocardiógrafo (HeartWare) de 12 derivações simultâneas e, a pressão arterial (PA), por meio de método auscultatório. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram avaliados por método espirométrico computadorizado respiração-a-respiração (MedGraphics Corporation [MGC]). Os seguintes resultados foram verificados: no (LA): [FC = 173,6 ± 8,6bpm; VO2 = 55,78 ± 5,93ml.kg.-1.min-1; velocidade = 14,6 ± 1,0km.h-1]; no exercício máximo [FC = 189,5 ± 11,4bpm; V E = 134,1 ± 15,9L.min-1; VO2máx. = 63,75 ± 4,93ml.kg.-1.min-1; velocidade = 17,8 ± 1,0km.h-1; Borg = 18,3 ± 1,3 pontos]. Concluindo: Os resultados, comparados com os da literatura especializada na modalidade futebol, demonstraram que os índices de LA e VO2máx. foram semelhantes e, até mesmo, superiores a vários de estudos publicados sobre essas duas variáveis em jogadores de futebol profissional. Entretanto, considerando as posições dos jogadores, não há um consenso definido sobre os índices mais adequados de LA e VO2máx. em futebolistas, mas, sim, sugestões.The aim of this study was to make an approach on the importance of the anaerobic threshold (AT) and the peak oxygen uptake in soccer players, and compare the results found in players to those existing in the specialized literature. An evaluation was made in 18 professional soccer players aged 24 ± 4; weight 72.5 ± 5.9 kg; height 176.5 ± 7.0 cm, and body surface 1.91 ± 0.15 m². Every athlete was evaluated after a 2 month training period. The soccer players were submitted to a maximum exercise test on treadmill, using incremental continuous protocol. The heart rate (HR) was recorded by means of an electrocardiograph (HeartWare) with 12 simultaneous leads and the arterial blood pressure (BP) by auscultation method. The pulmonary ventilation (V E), the oxygen uptake (VO2), the carbon dioxide production (VCO2) and the respiratory exchange rate (RER) were evaluated by means of the breath-by-breath spirometric computerized method (MedGraphics Corporation-MGC). The following results were verified in the AT: HR = 173.6 ± 8.6 bpm; VO2 = 55.78 ± 5.93 mlO2.kg-1.min-1; running velocity = 14.6 ± 1.0 km.h-1; maximum exercise: HR = 189.5 ± 11.4 bpm; V E = 134.1 ± 15.9 L.min-1; VO2 peak = 63.75 ± 4.93 mlO2.kg-1.min-1; maximum velocity = 17.8 ± 1.0 km.h-1; Borg scale = 18.3 ± 1.3 points. In conclusion, the results, when compared to those of specialized literature, proved the rate of AT and VO2 peak to be similar and even superior to several results published about such two variables in professional soccer players. Considering, however, the players' position, there is no definite consensus on the most adequate AT rates and VO2 peak in soccer players, but only suggestions.

Paulo Roberto Santos Silva; Angela Romano; Alberto Azevedo Alves Teixeira; Ana Maria Visconti; Carla Dal Maso Nunes Roxo; Gilberto Silva Machado; José Roberto Rivelino Vidal; Luís Antonio Inarra

1999-01-01

271

A importância do limiar anaeróbio e do consumo máximo de oxigênio (VO2 máx.) em jogadores de futebol/ The importance of the anaerobic threshold and maximum oxygen uptake (VO2 PEAK) for soccer players  

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese O objetivo deste estudo foi fazer uma abordagem sobre a importância do limiar anaeróbio (LA) e o consumo máximo de oxigênio (VO2máx.) em jogadores de futebol e comparar os resultados encontrados em nossos futebolistas com os da literatura especializada. Foram avaliados 18 jogadores de futebol profissional, com média de idade de 24 ± 4 anos, peso de 72,5 ± 5,9kg; estatura de 176,5 ± 7,0cm e superfície corpórea de 1,91 ± 0,15m². Todos os atletas foram avaliados (more) após um período de dois meses de treinamentos. Os futebolistas foram submetidos a teste máximo em esteira ergométrica, utilizando-se protocolo escalonado e contínuo. A resposta de freqüência cardíaca (FC) foi registrada por meio de um eletrocardiógrafo (HeartWare) de 12 derivações simultâneas e, a pressão arterial (PA), por meio de método auscultatório. A ventilação pulmonar (V E), o consumo de oxigênio (VO2), a produção de dióxido de carbono (VCO2) e a razão de troca respiratória (RER) foram avaliados por método espirométrico computadorizado respiração-a-respiração (MedGraphics Corporation [MGC]). Os seguintes resultados foram verificados: no (LA): [FC = 173,6 ± 8,6bpm; VO2 = 55,78 ± 5,93ml.kg.-1.min-1; velocidade = 14,6 ± 1,0km.h-1]; no exercício máximo [FC = 189,5 ± 11,4bpm; V E = 134,1 ± 15,9L.min-1; VO2máx. = 63,75 ± 4,93ml.kg.-1.min-1; velocidade = 17,8 ± 1,0km.h-1; Borg = 18,3 ± 1,3 pontos]. Concluindo: Os resultados, comparados com os da literatura especializada na modalidade futebol, demonstraram que os índices de LA e VO2máx. foram semelhantes e, até mesmo, superiores a vários de estudos publicados sobre essas duas variáveis em jogadores de futebol profissional. Entretanto, considerando as posições dos jogadores, não há um consenso definido sobre os índices mais adequados de LA e VO2máx. em futebolistas, mas, sim, sugestões. Abstract in english The aim of this study was to make an approach on the importance of the anaerobic threshold (AT) and the peak oxygen uptake in soccer players, and compare the results found in players to those existing in the specialized literature. An evaluation was made in 18 professional soccer players aged 24 ± 4; weight 72.5 ± 5.9 kg; height 176.5 ± 7.0 cm, and body surface 1.91 ± 0.15 m². Every athlete was evaluated after a 2 month training period. The soccer players were submit (more) ted to a maximum exercise test on treadmill, using incremental continuous protocol. The heart rate (HR) was recorded by means of an electrocardiograph (HeartWare) with 12 simultaneous leads and the arterial blood pressure (BP) by auscultation method. The pulmonary ventilation (V E), the oxygen uptake (VO2), the carbon dioxide production (VCO2) and the respiratory exchange rate (RER) were evaluated by means of the breath-by-breath spirometric computerized method (MedGraphics Corporation-MGC). The following results were verified in the AT: HR = 173.6 ± 8.6 bpm; VO2 = 55.78 ± 5.93 mlO2.kg-1.min-1; running velocity = 14.6 ± 1.0 km.h-1; maximum exercise: HR = 189.5 ± 11.4 bpm; V E = 134.1 ± 15.9 L.min-1; VO2 peak = 63.75 ± 4.93 mlO2.kg-1.min-1; maximum velocity = 17.8 ± 1.0 km.h-1; Borg scale = 18.3 ± 1.3 points. In conclusion, the results, when compared to those of specialized literature, proved the rate of AT and VO2 peak to be similar and even superior to several results published about such two variables in professional soccer players. Considering, however, the players' position, there is no definite consensus on the most adequate AT rates and VO2 peak in soccer players, but only suggestions.

Silva, Paulo Roberto Santos; Romano, Angela; Teixeira, Alberto Azevedo Alves; Visconti, Ana Maria; Roxo, Carla Dal Maso Nunes; Machado, Gilberto Silva; Vidal, José Roberto Rivelino; Inarra, Luís Antonio

1999-12-01

272

Formation and Thermochromism of VO2 Films Deposited by RF Magnetron Sputtering at Low Substrate Temperature  

Science.gov (United States)

Thermochromic VO2 films were deposited on substrates of silicon and Pyrex glass by reactive rf magnetron sputtering and characterized by thin-film X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM) and spectrophotometry. Films with a VO2 single phase were formed above a fairly low temperature of 300° C by controlling precisely the oxygen flow ratio. The use of a nucleated substrate improved the crystallinity of the VO2 films deposited at low temperature. A negative substrate bias appeared to have an effect of favoring the formation of a VO2 single phase at a substrate temperature as low as 250° C.

Jin, Ping; Tanemura, Sakae

1994-03-01

273

[Study on spectral property of phase transition of PcNi-VO2 films].  

Science.gov (United States)

Highly oriented VO2 thin films were deposited on sapphire substrate and [C8H17O]8 PcNi thin films were spin-coated onto VO2 thin films. The microstructure of VO2 thin films was studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated with infrared spectrometer. It was found that the mid-infrared transmittance of the complex films in the wavelength range 1.5 to 5.5 mm raised with PcNi coating. The thermochromism of PcNi/VO2 films did not changed compared with VO2 films and the transition temperature was the same as that of VO2. It can be anticipated that the optical limiting property of PcNi/VO2 films will be superior to that of VO2 thin films or PcNi thin films. PMID:18306765

Yuan, Hong-tao; Feng, Ke-cheng; Zhang, Xian-hui

2007-10-01

274

Active Timing Based Approach for Tracking Anonymous Peer-to-peer Network in VoIP  

Directory of Open Access Journals (Sweden)

Full Text Available Peer-to-peer VoIP calls are popular due to theirlow cost and convenience. When these calls are encrypted andanonymized the network becomes a secured one. Tracing of theanonymous VoIP call users are important and the tracedinformation about them should be sent to the server to knowhow long the users are in communication.The key challenge in tracking encrypted VoIP calls acrossanonymous communication system is to identify the correlationbetween the VoIP flows of the caller and the callee. Since all thetraffic of the peer-to-peer VoIP calls are encrypted, the best wayto track anonymous VoIP calls across the internet is using theActive timing based correlation. It is done by embedding aunique watermark into the inter-packet timing domain. Theanalysis shows that it only takes several milliseconds timeadjustment to make normal VoIP flows highly unique and theembedded delay value could be preserved across the low latencyanonymizing network. In this proposal, tracking of anonymousVoIP calls across internet was successfully achieved by usingactive time based correlation method and the resultsdemonstrate that tracing of anonymous peer-to-peer VoIP callson the internet is feasible and low latency anonymizing networksare susceptible to timing attacks.

Karthikeyan.C; Karthikeyan.V; Jerin Sajeev.C.R,; Merlin Moses.M,

2013-01-01

275

QoS-guaranteed burst transmission for VoIP service over optical burst switching networks  

Science.gov (United States)

We propose a burst transmission method that guarantees the voice over Internet protocol (VoIP) service. The proposed method consists of three techniques: round-robin burst assembly with slotted scheduling, priority control with void filling, and hop-based preemption. Each technique is utilized so that the burst loss probability and the burst transmission delay satisfy VoIP quality of service (QoS). We evaluate by simulation the performance of the proposed method in NSFNET with 14 nodes. Numerical examples show that our proposed method is effective for guaranteeing the VoIP QoS while accommodating a large number of VoIP users.

Tachibana, Takuji; Kasahara, Shoji

2007-08-01

276

Phase coexistence in the metal-insulator transition of a VO{sub 2} thin film  

Energy Technology Data Exchange (ETDEWEB)

Vanadium dioxide (VO{sub 2}) shows a metal-insulator transition (MIT) near room temperature, accompanied by an abrupt resistivity change. Since the MIT of VO{sub 2} is known to be a first order phase transition, it is valuable to check metallic and insulating phase segregation during the MIT process. We deposited (100)-oriented epitaxial VO{sub 2} thin films on R-cut sapphire substrates. From the scanning tunneling spectroscopy (STS) spectra, we could distinguish metallic and insulating regions by probing the band gap. Optical spectroscopic analysis also supported the view that the MIT in VO{sub 2} occurs through metal and insulator phase coexistence.

Chang, Y.J. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Koo, C.H. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Yang, J.S. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, Y.S. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, D.H. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, J.S. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of); Noh, T.W. [School of Physics and Research Center for Oxide Electronics, Seoul National University, Seoul 151-747 (Korea, Republic of)]. E-mail: twnoh@phya.snu.ac.kr; Kim, Hyun-Tak [Telecom. Basic Research Lab., ETRI, Daejeon 305-350 (Korea, Republic of); Chae, B.G. [Telecom. Basic Research Lab., ETRI, Daejeon 305-350 (Korea, Republic of)

2005-08-22

277

Relative Aerial Biomass Yield of Intercroped Alfalfa with Winter Forage Cereals/ Rendimiento Relativo de Biomasa Aérea en Intercultivos de Alfalfa con Cereales Forrajeros de Invierno  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En las regiones tropicales del mundo, el intercultivo está asociado con la producción de granos para la alimentación, mientras que en áreas templadas recibe mayor atención como medio de producción eficiente de forraje. El objetivo de este experimento fue determinar el rendimiento relativo de biomasa aérea en intercultivos de alfalfa (Medicago sativa L.) y cereales forrajeros de invierno. Se establecieron ocho sistemas producto de la combinación con especies de cer (more) eales con distintas fechas de siembra. Las mediciones de biomasa se realizaron en tres situaciones: monocultivo de alfalfa, monocultivo de cereales e intercultivo de alfalfa-cereal, calculándose el rendimiento relativo del intercultivo (RRI). Se empleó un diseño con arreglo bifactorial y dos repeticiones en bloques completos al azar. Los intercultivos de alfalfa-cereal generaron valores de RRI entre 0,71 y 0,83, lo que indicó que en una misma superficie es posible producir entre el 71 y 83% de la biomasa que ambos cultivos producirían en superficies separadas. Abstract in english In the tropical regions of the world, intercropping is mostly associated with food grain production, whereas it is receiving increased attention in temperate regions as a means of efficient forage production. The aim of this work was to determine the relative yield of aerial biomass in alfalfa or lucerne (Medicago sativa L.) and winter forage cereals intercrops. These were done in eight systems resulting from the combination of species sown at different dates. The biomass (more) was measured in three situations: alfalfa and cereal sole-crop and alfalfa-cereal intercrops, the relative biomass yields were calculated by the relative yield index (RYI). The field experiment was conducted as a bifactorial array in a randomized complete block design of two replicates. The alfalfa-cereal intercrops provided RYI values ranging from 0.71 to 0.83. This showed that it is possible to produce, in the same area, between 71 and 83% of the biomass that both crops would produce in separate ones.

Pereyra, Telmo; Pagliaricci, Héctor; Ohanian, Alfredo

2008-09-01

278

Ecuaciones alométricas para estimar biomasa y carbono en Quercus magnoliaefolia/ Allometric equations for estimating the above-ground biomass and carbon in Quercus magnoliaefolia Née  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish En el ejido El Zapote de la Reserva de la Biosfera "Sierra de Huautla", estado de Morelos, México, se seleccionaron doce árboles de Quercus magnoliaefolia Née y se determinó su biomasa en la parte aérea. El modelo alométrico quedó expresado como: B = 0.0345 * DAP29334 en donde B es la biomasa (kg) y DAP es el diámetro a la altura del pecho (cm), con un coeficiente de determinación (R²= 0.98; P(more) lineal múltiple que consideró el área basal (AB), la densidad específica de la madera (DEM) y la altura de los árboles (H). Una alta proporción de la varianza de la biomasa fue explicada solamente por el área basal. La DEM y H no incrementaron significativamente la precisión de los modelos. El porcentaje promedio de carbono en los árboles de Q. magnoliaefolia fue de 47.14 con valores de 46.29 % para el fuste, 46.83 % para las ramas y 48.31 % para el follaje. La proporción promedio de los componentes de la especie estudiada fue de 62.5 % para el fuste, 27.8 % para las ramas y 9.6 % para el follaje. Abstract in english At the El Zapote ejido in the "Sierra de Huautla" Biosphere Reserve in the state of Morelos, Mexico, twelve Quercus magnoliaefolia Née trees were selected and their above-ground biomass determined. The proposed allometric model was expressed as: B = 0.0345 * DBH2.9334, where B is biomass (kg) and DBH is diameter at breast height (cm), with a coefficient of determination (R²= 0.98; PO.001). In addition, above-ground biomass was estimated by a multiple linear regression b (more) ased on basal area (BA), specific gravity of wood (SGW) and tree height (H). A high proportion of the biomass variation was explained by basal area alone. SGW and H did not significantly increase the accuracy of the models. The average percentage of carbon in Q. magnoliaefolia trees was 47.14 with values of 46.29 % for the bole, 46.83 % for branches and 48.31 % for foliage. The average proportion of the components of the species studied was 62.5 % for the bole, 27.8 % for branches and 9.6 % for foliage.

Gómez-Díaz, Jesús D.; Etchevers-Barra, Jorge D.; Monterrosos-Rivas, Alejandro I.; Campo-Alvez, Julio; Tinoco-Rueda, Juan A.

2011-08-01

279

Estimación de la biomasa aérea de seis leguminosas leñosas del Chaco Árido (Argentina)/ Estimating aerial biomass of six woody Leguminosae of the Arid Chaco (Argentina)  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La posibilidad de contar con estimaciones confiables de la biomasa aérea de la vegetación leñosa resulta imprescindible para el manejo productivo, la conservación o la restauración de los ecosistemas de bosque. Sin embargo, no siempre se dispone de técnicas relativamente sencillas y no destructivas. Este trabajo presenta modelos de regresión para estimar la biomasa aérea total de seis especies arbustivas y arbóreas de la familia Fabaceae, nativas del Chaco Árido (more) (Prosopis flexuosa, Geoffroea decorticans, Cercidium praecox, Acacia furcatispina, Mimoziganthus carinatus y Prosopis torquata). Los modelos incluyeron distintas combinaciones del diámetro a la base (DAB) y la altura de los individuos. Todos ellos predijeron aceptablemente la biomasa por especie, si bien el de regresión lineal que utiliza el DAB² como variable independiente presentó el mejor ajuste. Las especies fueron agrupadas según sus rasgos comunes en: monopódicas de madera dura, multitallares de madera extremadamente pesada, monopódica de madera excesivamente pesada y monopódica y multitallar de madera extremadamente pesada y para cada uno de los grupos se generó una ecuación. Abstract in english Reliable estimates of biomass for the vegetation of the Arid Chaco forest is critical for its management, conservation or restoration. However, simple and non destructive techniques are not largely available. This study provides regression models aimed at estimating the aerial biomass of native shrub and tree species from the Arid Chaco, belonging to the Fabaceae family (Prosopis flexuosa, Geoffroea decorticans, Cercidium praecox, Acacia furcatispina, Mimoziganthus carina (more) tus and Prosopis torquata). An additional objective was to explore the feasibility of using a single equation for several species. The wood density differed significantly between species. Linear and nonlinear regression models of aerial biomass were adjusted for species, with different combinations of base diameter (DAB) and height as independent variables. The models properly predicted the biomass by species, the most appropriate being the linear regression model using DAB² as an independent variable. To establish differences in the behavior of species and, more precisely, in the ratio between total dry weight and DAB, the slope homogeneity was analyzed using a regression model with auxiliary variables. Taking into account the results obtained and the basic wood density and morphological growth structure, four groups of species have been postulated, and it was feasible to apply a single equation per group. The proposed groups are: (1) monopodial hardwood (Geoffroea decorticans and Cercidium praecox), (2) multi-stem shrubs of extremely heavy wood (Acacia furcatispina and Mimoziganthus carinatus), (3) monopodial of very heavy wood (Prosopis flexuosa) and (4) monopodial and multi-stem of extremely heavy wood (Prosopis torquata).

Iglesias, María del Rosario; Barchuk, Alicia Haydée

2010-04-01

280

VoSeq: a voucher and DNA sequence web application.  

Science.gov (United States)

There is an ever growing number of molecular phylogenetic studies published, due to, in part, the advent of new techniques that allow cheap and quick DNA sequencing. Hence, the demand for relational databases with which to manage and annotate the amassing DNA sequences, genes, voucher specimens and associated biological data is increasing. In addition, a user-friendly interface is necessary for easy integration and management of the data stored in the database back-end. Available databases allow management of a wide variety of biological data. However, most database systems are not specifically constructed with the aim of being an organizational tool for researchers working in phylogenetic inference. We here report a new software facilitating easy management of voucher and sequence data, consisting of a relational database as back-end for a graphic user interface accessed via a web browser. The application, VoSeq, includes tools for creating molecular datasets of DNA or amino acid sequences ready to be used in commonly used phylogenetic software such as RAxML, TNT, MrBayes and PAUP, as well as for creating tables ready for publishing. It also has inbuilt BLAST capabilities against all DNA sequences stored in VoSeq as well as sequences in NCBI GenBank. By using mash-ups and calls to web services, VoSeq allows easy integration with public services such as Yahoo! Maps, Flickr, Encyclopedia of Life (EOL) and GBIF (by generating data-dumps that can be processed with GBIF's Integrated Publishing Toolkit). PMID:22720030

Peña, Carlos; Malm, Tobias

2012-06-12

 
 
 
 
281

Is the Internet ready for VoIP?  

UK PubMed Central (United Kingdom)

There is a great interest today in voice communicationover the Internet (VoIP). If the Internet were to become theuniversal network for all communications needs, and thuswere to displace the telephone network for voice communication,it must be capable of providing the same level ofservice quality as the telephone network. Today, this doesnot seem to be the case. VoIP is plagued with packet lossand variable packet delay in the network. Although measuresare taken to overcome these problems (e.g., loss concealmentand adaptive playout), their effectiveness is limitedto certain ranges of network conditions. Thus it is ofgreat importance to understand the packet loss and delaycharacteristics of today's Internet, in order to understandthe effectiveness of the measures introduced to overcomethe impairments. To that end, we examine in detail measurementsof packet loss and delay taken over the Internet,and give a characterization thereof. We then comment onthe impact that they can have on the quality of VoIP, andon the effectiveness of the measures introduced to minimizetheir impact. This study is limited to measurementstaken only on Internet backbone networks, which representimportant components in long distance communication. Itreveals that packet loss and delay characteristics are notconsistent across all backbone networks. Some backbonenetworks exhibit fairly good characteristics and may offergood quality communication, leading to a confirmationthat packet voice is a sound approach. Other backbonenetworks exhibit undesirable characteristics that could notbe accommodated with any of the measures introduced today.We comment on the possible causes and on the improvementsthat need to be made in the Internet backbonenetworks to render them adequate f...

Fouad A. Tobagi; Athina P. Markopoulou; Mansour J. Karam

282

Decoupling of structural and electronic phase transitions in VO2  

Science.gov (United States)

Using optical, TEM and ultrafast electron diffraction experiments we find that single crystal VO2 microbeams gently placed on insulating substrates or metal grids exhibit different behaviors, with structural and metal-insulator transitions occuring at the same temperature for insulating substrates, while for metal substrates a new monoclinic metal phase lies between the insulating monoclinic phase and the metallic rutile phase. The structural and electronic phase transitions in these experiments are strongly first order and we discuss their origins in the context of current understanding of multi-orbital splitting, strong correlation effects and structural distortions that act cooperatively in this system.

Tao, Zhensheng; Han, Tzong-Ru T.; Mahanti, Subhendra D.; Duxbury, Phillip M.; Yuan, Fei; Ruan, Chong-Yu; Wang, Kevin; Wu, Junqiao

2013-03-01

283

?-K(VO2)2(PO4).  

UK PubMed Central (United Kingdom)

A new vanadium oxide, potassium bis-(dioxovanad-yl) phosphate, ?-K(VO2)2(PO4), has been synthesized by a solid-state reaction. In the title compound, the [V2PO8] framework is built up from infinite pyramidal [V2O8]? and [VPO7]? chains linked together by V-O-P bridges, leading to a three-dimensional framework which delimits two types of inter-secting tunnels running along [100] and [010] in which the four unique K(+) ions, showing coordination numbers of nine and ten, are located.

Ezzine Yahmed S; Ayed M; Zid MF; Driss A

2013-01-01

284

Results of an analysis of SDSS galaxies in the VO  

CERN Document Server

We present here the VO access to the results of an analysis of the spectra of Sloan Digital Sky Survey (SDSS) galaxies performed with the STARLIGHT code by Cid Fernandes et al. (2005). The results include for each galaxy the original SDSS spectrum, the best-fit synthetic spectrum, the star formation history, the pure emission line spectrum corrected from underlying stellar population (in SDSS emission line galaxies) and the intensity of several emission/absorption lines. The database will be accessible from the PGos3 at the end of summer 2007.

Schoenell, W; Fernandes, R Cid; Mateus, A; Terlevich, E; Terlevich, R; Santos, F de los; Torres-Papaqui, J P; Luridiana, V

2007-01-01

285

Observation of Mott Transition in VO_2 Based Transistors  

CERN Multimedia

An abrupt Mott metal-insulator transition (MIT) rather than the continuous Hubbard MIT near a critical on-site Coulomb energy U/U_c=1 is observed for the first time in VO_2, a strongly correlated material, by inducing holes of about 0.018% into the conduction band. As a result, a discontinuous jump of the density of states on the Fermi surface is observed and inhomogeneity inevitably occurs. The gate effect in fabricated transistors is clear evidence that the abrupt MIT is induced by the excitation of holes.

Kim, H T; Youn, D H; Maeng, S L; Kang, K Y; Kim, Hyun-Tak

2003-01-01

286

IP Telephony Deploying VoIP Protocols and IMS Infrastructure  

CERN Multimedia

All you need to know about deploying VoIP protocols in one comprehensive and highly practical reference - Now updated with coverage on SIP and the IMS infrastructure. This book provides a comprehensive and practical overview of the technology behind Internet Telephony (IP), providing essential information to Network Engineers, Designers, and Managers who need to understand the protocols. Furthermore, the author explores the issues involved in the migration of existing telephony infrastructure to an IP - based real time communication service. Assuming a working knowledge of IP and networking, i

Hersent, Olivier

2010-01-01

287

Bulk sensitive core-level photoemission spectroscopy of VO2  

International Nuclear Information System (INIS)

We have studied electronic structures of VO2 by soft and hard X-ray synchrotron core-level photoelectron spectroscopy. In our measurements, temperature and photon energy dependences of the V 2p core-level spectra are observed. Remarkable spectral changes are observed across the metal-insulator transition (MIT) at T=340K. A clear shoulder structure is observed on the lower binding energy side of the V 2p3/2 peak in the metallic phase. This shoulder structure, being stronger for larger h?, is interpreted as the well-screened feature by bulk conduction electrons.

2007-01-01

288

Analysis of VoIP Traffic with Multiple Packet Transfer  

Directory of Open Access Journals (Sweden)

Full Text Available Voice over Internet Protocol (VoIP) is a form of voice communication. Today Wireless LANs are providing a cost effective alternative for the voice communication. Initially the wireless access protocols are not suitable for the voice communication. Subsequently, new techniques are developed for the real time voice communication. In voice communication the delay is an important factor. In this paper a new technique is proposed for the voice over IEEE 802.11 WLANs. The proposed technique is compared with Modified ICF

Tara Chand, Vishal Srivastava

2012-01-01

289

VoIP Network Failure Detection and User Notification  

UK PubMed Central (United Kingdom)

The impact of network failures can be minimized if users are promptly notified by appropriately designedapplications. Specifically, for Voice-over-IP (VoIP) networks, an RTP/RTCP-based detection method can be used torapidly distinguish between network congestion and network failures. Users and network managers can exploit thisinformation in various ways, such as rapid network recovery or seeking application usage alternatives. In this paper, wepresent the main ideas behind these proposals, along with some analytical/simulation results, plus insights from aLinux-based implementation with its experimental results.

Mark Karol; P. Krishnan; J. Jenny Li

290

Intestinal absorption and secretion of radioactive vanadium (/sup 48/VO/sup -//sub 3/) in rats and effect of Al(OH)/sub 3/  

Energy Technology Data Exchange (ETDEWEB)

Sprague-Dawley rats (180-300 g) were fasted overnight and gavaged with 5 ..mu..mol Na/sub 3/VO/sub 4/ in 1.0 ml 0.9% NaCl containing 1 ..mu..Ci /sup 48/V. Control animals (n = 12) simultaneously received 1.0 ml diluent and experimental animals (n = 12) received 1 ml Al(OH)/sub 3/. Diluent and Al(OH)/sub 3/ were then given daily for 4 d. Urine and feces were collected separately each day. In control animals total /sup 48/V recovery (stool and urine) over 4 d was 86.6 +/- 2.4% of the administered dose. Although Al(OH)/sub 3/ insignificantly increased total /sup 48/V recovery (93.6 +/- 3.2%), it markedly increased excretion of /sup 48/V in the stool as compared to the urine (control:stool, 69.1 +/- 1.8%; urine, 12.5 +/- 1.3%; Al(OH)/sub 3/:stool, 85.7 +/- 1.5%; urine, 7.9 +/- 1.8%). Animals were then sacrificed and tissue uptake of tracer measured. The pattern of unexcreted /sup 48/V in tissues of both groups was kidney > bone > liver > intestine > muscle, but the tissue levels were uniformly higher in controls than in Al(OH)/sub 3/-treated animals. The ability of Al(OH)/sub 3/ to remove endogenous VO/sup -//sub 3/ was also examined. /sup 48/V was injected ip (n = 20). Half of the animals received diluent and half received 1.0 ml Al(OH)/sub 3/ by gavage daily for 4 d. There were no differences in the pattern of /sup 48/V tissue distribution and excretion. It is concluded that Al(OH)/sub 3/ may prevent tissue accumulation of VO/sup -//sub 3/ from dietary sources by reducing intestinal VO/sup -//sub 3/ absorption. (JMT)

Wiegmann, T.B. (Univ. of Kansas Medical Center, Kansas City); Day, H.D.; Patak, R.V.

1982-08-01

291

Significance of the velocity at VO2max and time to exhaustion at this velocity.  

UK PubMed Central (United Kingdom)

In 1923, Hill and Lupton pointed out that for Hill himself, 'the rate of oxygen intake due to exercise increases as speed increases, reaching a maximum for the speeds beyond about 256 m/min. At this particular speed, for which no further increases in O2 intake can occur, the heart, lungs, circulation, and the diffusion of oxygen to the active muscle-fibres have attained their maximum activity. At higher speeds the requirement of the body for oxygen is far higher but cannot be satisfied, and the oxygen debt continuously increases'. In 1975, this minimal velocity which elicits maximal oxygen uptake (VO2max) was called 'critical speed' and was used to measure the maximal aerobic capacity (max Eox), i.e. the total oxygen consumed at VO2max. This should not be confused with the term 'critical power' which is closes to the power output at the 'lactate threshold'. In 1984, the term 'velocity at VO2max' and the abbreviation 'vVO2max' was introduced. It was reported that vVO2max is a useful variable that combines VO2max and economy into a single factor which can identify aerobic differences between various runners or categories of runners. vVO2max explained individual differences in performance that VO2max or running economy alone did not. Following that, the concept of a maximal aerobic running velocity (Vamax in m/sec) was formulated. This was a running velocity at which VO2max occurred and was calculated as the ratio between VO2max (ml/kg/min) minus oxygen consumption at rest, and the energy cost of running (ml/kg/sec). There are many ways to determine the velocity associated with VO2max making it difficult to compare maintenance times. In fact, the time to exhaustion (tlim) at vVO2max is reproducible in an individual, however, there is a great variability among individuals with a low coefficient of variation for vVO2max. For an average value of about 6 minutes, the coefficient of variation is about 25%. It seems that the lactate threshold which is correlated with the tlim at vVO2max can explain this difference among individuals, the role of the anaerobic contribution being significant. An inverse relationship has been found between tlim at vVO2max and VO2max, and a positive one between vVO2max and the velocity at the lactate threshold expressed as a fraction of vVO2max. These results are similar for different sports (e.g. running, cycling, kayaking, swimming). It seems that the real time spent at VO2max is significantly different from an exhaustive run at a velocity close to vVO2max (105% vVO2max). However, the minimal velocity which elicits VO2max, and the tlim at this velocity appear to convey valuable information when analysing a runner's performance over 1500m to a marathon.

Billat LV; Koralsztein JP

1996-08-01

292

Modelo dinámico de crecimiento de la biomasa para Mytilus chilensis en sistemas de cultivo en líneas/ Dynamic biomass growth model for Mytilus chilensis in longline culture systems  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Este estudio propone un modelo de crecimiento dinámico de la biomasa para el bivalvo Mytilus chilensis, en sistemas de cultivos en línea. El modelo propuesto determina la biomasa a través del peso medio total y el número de choritos por metro lineal en la cuerda de engorda, calibrado usando datos reales. El peso medio se determina a través del modelo de von Bertalanffy modificado que incorpora la disponibilidad de alimento del ambiente y el ciclo reproductivo a trav? (more) ?s del Índice de Rendimiento Productivo, el que corresponde al cociente entre el peso en carne y el peso total. Por lo anterior, el peso medio está determinado por la disponibilidad de alimento y el crecimiento biológico de la especie. El modelo supone que el número de individuos de choritos por metro en la cuerda es el resultado tanto de la competencia intraespecífica entre individuos de M. chilensis como de la interespecífica con individuos del mitílido Aulacomya atra por el espacio disponible en la misma cuerda. Para modelar la competencia por el espacio disponible se utilizó la tasa de crecimiento, la superficie ocupada por los individuos y el porcentaje de presencia de M. chilensis y de A. atra. El estudio se realizó en la cuenca de Rilán, isla de Chiloé, sur de Chile, por un periodo de 18 meses. Se obtuvo un R² ajustado = 0,98, 0,93, y 0,94 para la variación del tamaño, de la densidad lineal y la biomasa, respectivamente, lo que indica que el modelo propuesto puede ser utilizado para predecir la biomasa en el tiempo. Abstract in english A dynamic biomass growth model for the mussel Mytilus chilensis in longline culture systems in proposed. This model determines the biomass by estimating the average weight and the number of mussels per meter of seeded rope, using real data. The average weight is estimated using the von Bertalanffy model modified to incorporate the availability of food in the environment and the reproductive cycle given by the Meat Yield Index, which is the quotient between the meat weight (more) and the total weight. Therefore, the average weight is determined by the availability of food and the biological growth of the species. The model assumes that the number of mussel individuals per meter in the rope is the result of both the species intraspecific competition among M. chilensis individuals and the interspecific competition with individuals of the mytilid Aulacomya atra for the available space in the same seeded rope. The growth rate, the occupied surface and the presence percentage of M. chilensis and A. atra were used to model the competition for the available space. The study was performed at the Rilán basin in the Chiloé Island, southern Chile, during an 18-month period. The results obtained were an R² adjusted = 0.98, 0.93, and 0.94 for the variation in size, lineal density and biomass, respectively, which indicate that the proposed dynamic model can be used to predict the biomass over time.

Marambio, José; Maturana, Sergio; Campos, Bernardita

2012-04-01

293

VO2 max Characteristics of Male Professional Soccer Players 1989-2012.  

Science.gov (United States)

PURPOSE: The purpose of this investigation was to quantify VO2 max performance in soccer as a function of performance level, position, age and time of season. In addition, we examined the evolution of VO2 max among professional players over a 23 year period. METHODS: 1545 male soccer players (22 ±4 yr, 76 ±8 kg, 181 ±6 cm) tested VO2 max at the Norwegian Olympic Training Center between 1989 and 2012. RESULTS: No differences in VO2 max were observed among national team players, 1st - 2nd division players and juniors. Midfielders had higher VO2 max than defenders, forwards and goalkeepers (pmax than 23-26 yr players (p=0.016). The players had 1.6 and 2.1 % lower VO2 max during off season compared to pre season (p=0.046) and in season (p=0.021), respectively. Relative to body mass, VO2 max among the professional players in this study has not improved over time. Professional players tested during time epoch 2006-2012 actually had 3.2 % lower VO2 max than those tested 2000-2006 (p=0.001). CONCLUSIONS: This study provides effect magnitude estimates for the influence of performance level, player position, age, and season time on VO2 max in male elite soccer. Our findings from a robust dataset indicate that VO2 max values ~ 62-64 mL x min-1x kg-1 fulfill the demands for aerobic capacity in male professional soccer and that VO2 max is not a clearly distinguishing variable separating players of different standard. PMID:23412586

Tønnessen, Espen; Hem, Erlend; Leirstein, Svein; Haugen, Thomas; Seiler, Stephen

2013-02-14

294

Predicción del contenido intracelular de trehalosa en el proceso de producción de biomasa de Saccharomyces cerevisiae/ Predicting trehalose cytoplasmic content during a Saccharomyces cerevisiae biomass production process  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La trehalosa es un carbohidrato dimérico componente de la levadura de panificación Saccharomyces cerevisiae, y es considerado como indicador de la capacidad fermentativa y de la viabilidad de las células. En procesos de producción de levadura, se busca inducir una acumulación intracelular de trehalosa. Por ser un compuesto citoplásmico, la cuantificación de la trehalosa requiere de tomas de muestra y de métodos analíticos posteriores. Así, el conocimiento del co (more) ntenido citoplásmico de trehalosa es siempre ulterior al desarrollo del proceso de producción de biomasa, y esto dificulta el ajuste en tiempo real de parámetros de operación para incrementar la cantidad de trehalosa en la biomasa. Por tanto, se requiere de alguna alternativa para estimación de la trehalosa intracelular en tiempo real. Este trabajo presenta una opción de predicción basada tanto en el metabolismo celular implicado durante la biosíntesis de trehalosa, como en un algoritmo de redes neuronales dinámicas para la estimación de la concentración intracelular del carbohidrato. Abstract in english Trehalose is a dimeric carbohydrate and yeast biomass component generally used as an indicator of good viability and fermentation capacity. Yeast biomass production processes aim at inducing an intracellular accumulation of trehalose. However, during a production process, the trehalose must be quantified by off-line analytical methods after sample taking because it is a cytoplasmic compound. Thus, knowing experimental measurements of yeast trehalose content is always dela (more) yed. As a result, not oportune actions can be implemented in order to lead the production process toward a high intracellular trehalose accumulation in the produced biomass. Therefore, an online estimation method to forecast real-time intracellular trehalose content in yeast is developed. It is based on the main metabolic events involved in trehalose biosynthesis, as well as on a differential neural network algorithm to estimate trehalose concentration in the cytoplasm.

Aranda, J. S.; Cabrera, A. I.; Chairez, J. I.

2008-04-01

295

Gasificación de biomasa residual en el sector floricultor, caso: Oriente Antioqueño/ Gasification of waste biomass in the flower industry, case: Eastern Antioquia  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Este artículo presenta los resultados de gasificación de una mezcla de 1/3 de cada especie de biomasa residual del cultivo de pompón, áster y hortensia con vapor de agua como agente gasificante, en un reactor a escala de laboratorio. La biomasa, como materia prima recibió un secado solar antes de iniciar el proceso de gasificación, se realizó también un procedimiento de reducción de tamaño de partícula a fin de obtener geometrías acordes al proceso de gasifica (more) ción, se caracterizó mediante el análisis próximo y último y se estableció como temperatura de operación del reactor un rango de 700 a 750°C. Como resultado, la composición del gas de síntesis producido fue analizada por cromatografía gaseosa y para el promedio de producción se obtienen: CH4 2,8 - 5%v, CO 9,3 - 22,2%v, H2 30,3 - 46,6%v. Abstract in english This paper presents the results of gasification of a mixture of 1/3 of each kind of residual biomass cultivation pompon, hydrangea and aster with steam as a gasifying agent in a laboratory scale reactor. The biomass feedstock received a solar drying before starting the gasification process, there was also a method for particle size reduction to obtain consistent geometries with gasification process, was characterized by proximate and ultimate analysis and established as r (more) eactor operating temperature range of 700 to 750°C. As a result, the composition of the produced synthesis gas was analyzed by gas chromatography and the average yield obtained: CH4 2.8 to 5%v, CO 9.3 to 22.2%v, H2 30.3 to 46.6%v.

Yepes Maya, Diego Mauricio; Chejne Janna, Farid

2012-12-01

296

AEROBIC AND STRENGTH TRAINING RESPONSES IN THE VO2max  

Directory of Open Access Journals (Sweden)

Full Text Available The strength training of produces improvements in the skeletal muscle as to the muscular hypertrophy, already the aerobic training produces an increase in him I number and in the size of the mitochondria. The objective was verifying the answers of the aerobic training and of force in the aerobic variables. The study was composed of 3 groups. The Aerobic Group (G1) that performed 6 weeks of training of aerobic, the Strength Group (G2) that did a program of 6 strength training weeks and the Group Control (GC). The evaluations of the study occurred in 2 moments: before of the training and in the week 6. We evaluate the VO2MAX, to mechanical power and the IErg. The G1 presented significant differences in all the variables analyzed, while the G2 presented significant difference in the VO2MÁX The study found an increase more marked in the aerobic instalments as answer of the aerobic training regarding the of force.

Sandro Fernandes da Silva; Cíntia Campolina Duarte Rocha; Pilar Sánchez Collado; José Antonio De Paz

2007-01-01

297

Crystal chemistry of LiVO{sub 2}  

Energy Technology Data Exchange (ETDEWEB)

Large single crystal plates of Li{sub 1-x}VO{sub 2} (x {approx_equal} 0.2) have been first grown using the Li{sub 2}O-B{sub 2}O{sub 3} flux method. Precession photographs reveal that an additional superstructure is formed on the basic ordered rock salt (ORS) structure at room temperature, and is released above transition temperature forming the ideal ORS structure. Small amount of LiV{sub 2}O{sub 4} decomposed partially from the Li{sub 1-x}VO{sub 2} crystals on heating above T{sub c} is also confirmed. Average structure analysis based on the ORS structure reveals that there exists large anisotropy on the thermal ellipsoid of V-site. The results of X-ray diffraction and the EX-AFS analysis at room temperature indicate that the superstructure is originated in formation of the V{sub 3}-trimers, and the displacement of V ions is estimated to be 0.16 A. Three kinds of stacking sequence of V{sub 3}-trimers are proposed to explain the intensity distributions of superstructure reflections. Temperature dependence of electrical resistivity and magnetic susceptibility are measured. Significant anisotropy in both of them is observed, indicating two-dimensional feature of this compound. (author)

Imai, Katsuhiro; Takei, Humihiko [Tokyo Univ. (Japan). Inst. for Solid State Physics

1996-08-01

298

Elastic properties of VO2 from first-principles calculation  

Science.gov (United States)

We used first-principles methods to calculate the elastic properties of rutile (R) structure and monoclinic (M1: space group P21/c, M2: space group C2/m) structure VO2, including single-crystal elastic constants cij's, polycrystalline bulk modulus, shear modulus, Young's modulus and elastic anisotropy ratio. We found that the energy difference among the R, M1 and M2 phases is small, indicating that it is easy to transit among them under a perturbation. Furthermore, from the pressure dependence of cij's, we also found that the structural instability (or phase transition) will occur when the volumes of the three phases are slightly smaller than their equilibrium volumes. Additionally, the R and M2 phases are predicted to be harder than the M1 phase, indicated by their larger bulk moduli and shear moduli. The elastic anisotropy of the M2 phase is larger than the M1 and R phases. The presently predicted elastic properties of VO2 provide helpful guidance for the strain energy estimation and stress analysis in nano-electronic devices.

Dong, Huafeng; Liu, Hongfei

2013-08-01

299

Influence of acute moderate hypoxia on time to exhaustion at vVO2max in unacclimatized runners.  

UK PubMed Central (United Kingdom)

Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (VO2max) and the minimal velocity eliciting VO2max (vVO2max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2,400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vO2 max in a random order (one in N and the other in H). The decrease in VO2max between N and H showed a great degree of variability amongst subjects as VO2max decreased by 8.9 +/- 4 ml x min(-1) x kg)(-1) in H vs. N conditions (-15.3 +/- 6.3 % with a range from -7.9 % to -23.8 %). This decrease in VO2max was proportional to the value of VO2max (VO2max vs. delta VO2max N-H, r = 0.75, p = 0.03). The time run at vVO2max was not affected by hypoxia (483 +/- 122 vs. 506 +/- 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vVO2max during hypoxia, the greater the runners increased their time to exhaustion at vVO2max (vVO2max N-H vs. tlim @vVO2max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vVO2max, and the increase in run time at vVO2max in hypoxia.

Billat VL; Lepretre PM; Heubert RP; Koralsztein JP; Gazeau FP

2003-01-01

300

Influence of acute moderate hypoxia on time to exhaustion at vVO2max in unacclimatized runners.  

Science.gov (United States)

Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (VO2max) and the minimal velocity eliciting VO2max (vVO2max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2,400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vO2 max in a random order (one in N and the other in H). The decrease in VO2max between N and H showed a great degree of variability amongst subjects as VO2max decreased by 8.9 +/- 4 ml x min(-1) x kg)(-1) in H vs. N conditions (-15.3 +/- 6.3 % with a range from -7.9 % to -23.8 %). This decrease in VO2max was proportional to the value of VO2max (VO2max vs. delta VO2max N-H, r = 0.75, p = 0.03). The time run at vVO2max was not affected by hypoxia (483 +/- 122 vs. 506 +/- 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vVO2max during hypoxia, the greater the runners increased their time to exhaustion at vVO2max (vVO2max N-H vs. tlim @vVO2max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vVO2max, and the increase in run time at vVO2max in hypoxia. PMID:12582946

Billat, V L; Lepretre, P M; Heubert, R P; Koralsztein, J P; Gazeau, F P

2003-01-01

 
 
 
 
301

Liquidus of the systems Li parallel WO4,F,Cl(VO3) and Li parallel WO4,VO3,Cl(Br)  

International Nuclear Information System (INIS)

[en] The method of differential thermal analysis is used to study the crystallization nature of components in four ternary eutectic systems formed by lithium tungstate. The data for binary LiVO3-LiCl, Li2VO4-LiVO3, LiVO3-LiBr, Li2WO4-LiBr systems are obtained for the first time. The majority of liquidus curves are simple and permit to give their precise description by the second order equations. For ternary eutectic systems phase diagrams are presented as the crossing of three surfaces of the second order. The coordinates of nonvariant points are specified by projection thermographic method

1987-01-01

302

Predictability of VO2 max from submaximal cycle ergometer and bench stepping tests.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The predictability of the maximal oxygen uptake (VO2 max) was studied using progressive and steady state protocols for cycle ergometry and bench stepping. The subjects were 12 healthy men, 23-58 years old. Prediction of VO2 max was made by extrapolation of the heart rate and O2 uptake at several sub...

Fitchett, M A

303

Validity of 20-MST for predicting VO2max of adult Singaporean athletes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This investigation compared the results of direct and indirect measurements of maximum oxygen uptake (VO2max) of an Asian population. Twenty subjects (16 male, 4 female), all of whom were physical education students, were assessed directly using laboratory treadmill running to determine VO2max. The ...

Sproule, J; Kunalan, C; McNeill, M; Wright, H

304

Time limit at VO2max velocity in elite crawl swimmers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

he purpose of this study is to assess, with elite crawl swimmers, the time limit at the minimum velocity corresponding to maximal oxygen consumption (TLim-vVO2max), and to characterize its main determinants. Eight subjects performed an incremental test for vVO2max assessment and, forty-eight hours l...

Ricardo Fernandes; Kari Keskinen; Paulo Colaço; Ana Querido; Leandro Machado; Pedro Morais; Daniel Novais; Daniel Marinho

305

Transient VO2 Characteristics in Children at the Onset of Steady-Rate Exercise.  

Science.gov (United States)

|Transient oxygen uptake (VO2) was studied in 28 children ranging in age from seven to fourteen. It was found that the VO2 halftime is similar to that of adults and that younger children attained a steady rate quicker than older children. (Authors/FG)|

Freedson, Patty S.; And Others

1981-01-01

306

Switchable vanadium dioxide (VO2) metamaterials fabricated from tungsten doped vanadia-based colloidal nanocrystals  

Science.gov (United States)

We report the fabrication of thermochromic VO2-based metamaterials using solution-processable colloidal nanocrystals. Vanadium-based nanoparticles are prepared through a non-hydrolytic reaction, resulting in stable colloidal dispersions in solution. Thermochromic nanocrystalline VO2 thin-films are prepared via rapid thermal annealing of colloidal nanoparticles coated on a variety of substrates. Nanostructured VO2 can be patterned over large areas by nanoimprint lithography. Precise control of tungsten (W) doping concentration in colloidal nanoparticles enables tuning of the phase transition temperature of the nanocrystalline VO2 thin-films. W-doped VO2 films display a sharp temperature dependent phase transition, similar to the undoped VO2 film, but at lower temperatures tunable with the doping level. By sequential coating of doped VO2 with different doping concentrations, we fabricate ?smart? multi-layered VO2 films displaying multiple phase transition temperatures within a single structure, allowing for dynamic modulation of the metal-dielectric layered structure. The optical properties programmed into the layered structure are switchable with temperature, which provides additional degrees of freedom to design tunable optical metamaterials.

Paik, Taejong; Hong, Sung-Hoon; Gordon, Thomas; Gaulding, Ashley; Kagan, Cherie; Murray, Christopher

2013-03-01

307

A Voice Priority Queue (VPQ) Fair Scheduler for the VoIP over WLANs  

Directory of Open Access Journals (Sweden)

Full Text Available Transmission of VoIP over packet switching networks is one of the rapidly emerging real-time Internet Protocol. The real-time application of the Voice over Internet Protocol (VoIP) is growing rapidly for it is more flexible than the traditional Public Switched Telephone Networks systems (PSTN). Meanwhile, the VoIP deployment on Wireless Local Area Networks (WLANs), which is based on IEEE 802.11 standards, is increasing. Currently, many schedulers have been introduced such as Weighted Fair Queueing (WFQ), Strict Priority (SP) General processor sharing (GPS), Deficit Round Robin (DRR), andContention-Aware Temporally fair Scheduling (CATS). Unfortunately, the current scheduling techniques have some drawbacks on real-time applications and therefore will not be able to handle the VoIP packetsin a proper way. The objective of this research is to propose a new scheduler system model for the VoIP application named Voice Priority Queue (VPQ) scheduler. The scheduler system model is to ensureefficiency by producing a higher throughput and fairness for VoIP packets. In this paper, only the First Stage of the VPQ packet scheduler and its algorithm are presented. Simulation topologies for VoIP traffic were implemented and analyzed using the Network Simulator (NS-2). The results show that this method can achieve a better and more accurate VoIP quality throughput and fairness index.

Kashif Nisar; Abas Md Said,; Halabi Hasbullah

2011-01-01

308

Raman spectroscopic studies on CeVO4 at high pressures  

International Nuclear Information System (INIS)

Raman scattering investigations of CeVO4 at high pressures is reported. Polycrystalline CeVO4 was prepared by solid state reaction of CeO2 and V2O5. High pressure Raman spectroscopic measurements were carried out as per experimental details given

2011-01-01

309

MAXIMAL OXIGEN UPTAKE (VO2 MAX) AS THE INDICATOR OF PHYSICAL WORKING CAPACITY IN SPORTSMEN  

Directory of Open Access Journals (Sweden)

Full Text Available The term “aerobic capacity” represents the sum of aerobic metabolic processes in human organism. It is the basis of the physical working capacity. Value of the maximal oxygen uptake (VO2max) is the best indicator for the aerobic capacity evaluation.The purpose of this study was to check the possibility of using VO2max as the indicator of aerobic capacity in sportsmen and to check differences in VO2max values in regard to non-sportsmen.The goals were: 1.Analyses of the VO2max values in sportsmen of various sports 2. Comparison of values of sportsmen with the values of non-sportsmen.This study included 67 sportsmen (rowers, football players and judoists) and 28 nonsportsmen. VO2max was measured by using a direct method.The results obtained show statistically higher VO2max values in rowers (4,52 L/min - 55,8 mL/kg/min) in regard to football players (4,2 L/min – 53,6 mL/kg/min), judoists (3,58 L/min - 47,2 mL/ kg/min) and non-sportsmen (3,28 L/min – 42,3 mL/kg/min). Successful rowing requires high anaerobic capacity and, therefore, high VO2max.These results show higher values of VO2max in sportsmen in regard to non-sportsmen, which is the result of training only.

Nenad Ponorac; Amela Matavulj; Nikola Grujic; Zvezdana Rajkovaca; Pedja Kovacevic

2005-01-01

310

Effect of Toe Clips During Bicycle Ergometry on VO2 max.  

Science.gov (United States)

|Eight men participated in three randomized maximal oxygen uptake tests to investigate the hypothesis that the use of toe clips on bicycle ergometers produced a higher VO2 max. No significant difference in mean VO2 max or performance time was observed. (Author/MT)|

Moffat, Roger S.; Sparling, Phillip B.

1985-01-01

311

Submaximal Treadmill Exercise Test to Predict VO[subscript 2]max in Fit Adults  

Science.gov (United States)

This study was designed to develop a single-stage submaximal treadmill jogging (TMJ) test to predict VO[subscript 2]max in fit adults. Participants (N = 400; men = 250 and women = 150), ages 18 to 40 years, successfully completed a maximal graded exercise test (GXT) at 1 of 3 laboratories to determine VO[subscript 2]max. The TMJ test was completed…

Vehrs, Pat R.; George, James D.; Fellingham, Gilbert W.; Plowman, Sharon A.; Dustman-Allen, Kymberli

2007-01-01

312

Non-Exercise Estimation of VO[subscript 2]max Using the International Physical Activity Questionnaire  

Science.gov (United States)

Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO[subscript 2]max) as well as sub-maximal exercise testing. The International Physical Activity Questionnaire is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO[subscript…

Schembre, Susan M.; Riebe, Deborah A.

2011-01-01

313

Modified Secret Sharing over a Single Path in VoIP with Reliable Data Delivery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Voice over Internet Protocol (VoIP) is a new fancy and up growing technology. A major change in telecommunication industry is VoIP. The transmission of Real time voice data is not as easy as ordinary text data. The real time voice transmission faces lot of difficulties. It suffers from pac...

K.Maheswari; M. Punithavalli

314

Labeled VoIP Data-set for Intrusion Detection Evaluation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

VoIP has become a major application of multimedia communications over IP. Many initiatives around the world focus on the detection of attacks against VoIP services and infrastructures. Because of the lack of a common labeled data-set similarly to what is available in TCP/IP network-based intrusion d...

Nassar, Mohamed; Radu, State; Festor, Olivier

315

A Topology-Aware Relay Lookup Scheme for P2P VoIP System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Because of the best-effort service in Internet, direct routing path of Internet may not always meet the VoIP quality requirements. Thus, many researches proposed Peer-to-Peer VoIP systems such as SIP+P2P system, which uses relay node to relay RTP stream from the source node to the destination node a...

Xiuwu ZHANG; Ruifeng GUO; Weimin LEI; Wei ZHANG

316

Investigation of VO-Zni native donor complex in MBE grown bulk ZnO  

Science.gov (United States)

In this paper, we have experimentally investigated the theoretical predictions of VO-Zni to be a native donor in ZnO. Intrinsically zinc-rich n-type ZnO thin films having ND ˜ 6.23 × 1018 cm-3 grown by molecular beam epitaxy on Si (0 0 1) substrate were annealed in oxygen environment at 500-800 °C, keeping a step of 100 °C for 1 h, each. Room temperature Hall measurements demonstrated that free donor (VO-Zni) concentration decreased exponentially and Arrhenius plot yielded activation energy to be 1.2 ± 0.01 eV. This value is in agreement with theoretically reported activation energy of VO-Zni donor complex in ZnO. We argue; this observation can be explained by two-step process: (i) incoming oxygen fills VO of VO-Zni complex leaving behind Zni; (ii) Zni releases its energy and moves to a lower energy state with respect to the conduction band minima and/or occupies an inactive location. Consequently, Zni-VO complex loses its donor role in the lattice. Our experimental data supported theoretical predictions of VO-Zni to be a native donor. Results from photoluminescence spectroscopy carried out on Zn-rich ZnO additionally justify the existence of VO-Zni complex.

Asghar, M.; Mahmood, K.; Ferguson, I. T.; Raja, M. Yasin A.; Xie, Y. H.; Tsu, R.; Hasan, M.-A.

2013-10-01

317

Feasibility Study of VoIP Integration into the MYSEA Environment.  

Science.gov (United States)

Voice over Internet Protocol (VoIP) is becoming popular due to its low cost and the management advantages it offers over traditional PSTN phone systems. VoIP is widely implemented with H.323 and Session Initiation Protocol (SIP) standards. However, both p...

L. Tse

2005-01-01

318

Ip-Telefoni ur ett Sarbarhetsperspektiv( A Vulnerability Perspective on VoIP).  

Science.gov (United States)

This report presents the results of a project, for the National Post and Telecom Agency (PTS), in which VoIP is studied from a vulnerability perspective. The aim of the project has been to study vulnerabilities of VoIP and the possible consequences for so...

S. Barck-Hoist H. Christiansson A. Vidstroem

2005-01-01

319

One step synthesis of monoclinic VO2 (B) bundles of nanorods: Cathode for Li ion battery  

International Nuclear Information System (INIS)

[en] One of the metastable phases of vanadium dioxide, VO2(B) bundles of nanorods and microspheres have been synthesized through a simple hydrothermal method by dispersing V2O5 in aqueous quinol. The obtained products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and electrochemical discharge–charge test for lithium battery. It was found that the morphologies of the obtained VO2(B) can be tuned by manipulating the relative amount of quinol. The electrochemical test found that the bundles of nanorods exhibit an initial discharge capacity of 171 mAh g?1 and its almost stabilized capacity was reached to 108 mAh g?1 after 47 cycles at a current density of 0.1 mA g?1. The formation mechanism of the VO2(B) bundles of nanorods and microspheres was also discussed. - Highlights: ? VO2(B) bundles of nanorods and microspheres were prepared by hydrothermal route at 180 °C for 1 day. ? In this method for the synthesis of VO2(B), we are the first to use quinol as a reducing agent. ? Morphologies of the obtained VO2(B) can be tuned by manipulating the relative amount of quinol. ? VO2(B) exhibits an initial capacity of 171 mAh g?1 and reached to 108 mAh g?1 after 47 cycles. ? The formation mechanism of the VO2(B) bundles of nanorods and microspheres is also discussed.

2012-01-01

320

V?O2max may not be reached during exercise to exhaustion above critical power.  

UK PubMed Central (United Kingdom)

PURPOSE: This study was designed to determine whether V?O(2) reaches a maximum, equivalent to that attained in an incremental exercise test to exhaustion, during "submaximal" fatigue-inducing constant-power exercise bouts above critical power (CP). METHODS: Nine males (age = 24.6 ± 3.6 yr, height = 182.8 ± 6.9 cm, weight = 77.8 ± 12.1 kg) and four females (age = 29.0 ± 7.3 yr, height = 170.8 ± 3.2 cm, weight = 61.8 ± 8.2 kg) underwent an incremental V?O(2max) test (IET) on a cycle ergometer, followed by four or five randomly assigned constant-power exercise bouts to exhaustion, on separate days. The CP for each subject was estimated using linear and nonlinear regression. RESULTS: IET V?O(2max) averaged 3.55 ± 0.92 L·min (RER = 1.21 ± 0.05, HR = 186 ± 10 bpm, 96.1% ± 6.3% of age-predicted maximum). Mean peak V?O(2) (range = 3.32 ± 0.88 to 3.54 ± 0.91 L·min) during the three highest constant-power bouts (two of which were 53 to 82 W less than peak power output attained during IET) was not significantly different from IET V?O(2max). Eleven of 13 subjects exceeded their IET V?O(2max) during at least one of the constant-power exercise bouts. However, peak V?O(2) (3.11 ± 0.79 L·min) during the lowest constant-power exercise bout, which ranged from 10 to 36 W above CP estimated with a two-parameter nonlinear model, was significantly lower than IET V?O(2max) (88.2% ± 9.4% of IET V?O(2max)). CONCLUSIONS: At power outputs above CP, V?O(2) does not necessarily increase to maximum during constant-power exercise to exhaustion. In addition, the highest V?O(2) values measured during a traditional V?O(2) "max" test (i.e., IET) may not reflect the highest attainable V?O(2) despite V?O(2max) criteria being met.

Sawyer BJ; Morton RH; Womack CJ; Gaesser GA

2012-08-01

 
 
 
 
321

Microstructures and thermochromic properties of tungsten doped vanadium oxide film prepared by using VO{sub X}-W-VO{sub X} sandwich structure  

Energy Technology Data Exchange (ETDEWEB)

Tungsten doped vanadium oxide (VO{sub X}) thin films were prepared by oxygen annealing VO{sub X}-W-VO{sub X} sandwich layers. X-ray photoelectron spectroscopy, X-ray diffraction and field emission scanning electron microscope were employed to characterize the compositions, crystal structures and surface morphologies, respectively. It was demonstrated that sandwich structure suppressed the crystallization of VO{sub X}, and that V{sup 5+} was reduced by diffused W atom to V{sup 4+}. The results of surface morphologies indicated that the grain arrangement of W doped vanadium dioxide film exhibited some regular patterns compared with the random grain distribution of undoped film. Electrical measurements showed that the square resistance of V{sub 2}O{sub 5} film and semiconductor-metal transition temperature of VO{sub 2}-V{sub 2}O{sub 5} film decreased obviously after W doping. In addition, thermal hysteresis loop was observed in W doped V{sub 2}O{sub 5} film with thick W middle layer. The investigation of optical properties indicated that the optical band gap of W doped V{sub 2}O{sub 5} film decreased with the increase of thickness of W middle layer, and the optical switching performance in the near-infrared range of VO{sub 2}-V{sub 2}O{sub 5} slightly weakened after W doping.

Luo Zhenfei, E-mail: zhfluo@yahoo.com.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Wu Zhiming, E-mail: zmwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Xu Xiangdong; Du Mingjun; Wang Tao; Jiang Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

2011-05-25

322

Thermochromic properties of VO2 thin film on SiNx buffered glass substrate  

Science.gov (United States)

VO2 thin films were deposited on soda lime glass substrates with silicon nitride sodium-diffusion barrier layer as diffusion barrier, in order to investigate the effect of sodium ion diffusion on the formation of VO2. SiNx layers with thicknesses over 30 nm were found to successfully prevent sodium ion diffusion in VO2 thin film and also contribute to the formation of VO2 thin film, which was confirmed by XRD spectra and XPS measurements. The change of infrared transmittance at 2500 nm wavelength with temperature change from room temperature to 80 °C was increased significantly, and the optical hysteresis width of the sample decreased by almost 6 K as well. The results suggest that applying diffusion barrier can improve the thermochromic properties of the VO2 films for energy-saving smart coatings, and silicon nitride can be one of the effective materials to prevent sodium ion diffusion.

Koo, Hyun; You, HyunWoo; Ko, Kyeong-Eun; Kwon, O.-Jong; Chang, Se-Hong; Park, Chan

2013-07-01

323

Analysis of multi-layer VO{sub x} thin film for uncooled IR detectors  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we analyzed multi VO{sub x} thin films to use as IR absorbing layer of uncooled IR devices. We used the new structure to fabricate VO{sub x} thin film that has improved IR absorbing characteristics. We deposited multi VO{sub x} thin films on SiN{sub x} by reactive RF magnetron sputtering method with different conditions. We changed the thickness of V and V{sub 2}O{sub 5} thin films and O{sub 2}/Ar gas ratio. With this method, we could fabricate multi VO{sub x} thin films that have improved IR absorbing characteristics. As the result of this, we obtained that TCR(Temperature coefficient of Resistance) value of multi layer VO{sub x} thin films was about -2.0 %/K and resistivity was {approx}1 {omega}cm.

Park, C. W.; Moon, Sung [KIST, Seoul (Korea, Republic of); Chung, H. B. [Kwangwoon Univ., Seoul (Korea, Republic of)

2001-12-01

324

Synthesis and Characterization of Highly Visible―light Active Monoclinic Mesoporous BiVO4  

Directory of Open Access Journals (Sweden)

Full Text Available Ordered nanocrystalline mesoporous BiVO4 with pure phase was successfully synthesized at 550¡æ via nanocasting using cubic MCM―48 molecular sieves as hard template. The long―range ordered mesostructure was characterized by XRD, TEM, BET as well as UV―Vis spectrophotometer. Compared with the BiVO4 synthesized by conventional hydrothermal method, the nanocasting mesoporous BiVO4 has the average pore diameter of 16.8nm, pore volume of 0.1 cm3/g and specific surface area up to 22.9 m2/g. The structure decreases the recombination of optical excitation electrons and holes efficiently, so the mesoporous BiVO4 has an excellent photocatalytic activity in the visible light region. As a result, the photocatalytic efficiency of mesoporous BiVO4 for xanthate in 90min reaches 78%.

XIAO Qi, GAO Lan, ZHANG Xiang

2011-01-01

325

An Efficient VoIP System to Promote Voice Access Business  

UK PubMed Central (United Kingdom)

VoIP is a rapidly growing area with great market potential. To promote it for both commercialand research purposes, we are developing an efficient voice access system based on state-of-art Motorolacommunication techniques. It is composed of a communication subsystems, a voice interface, and aninformation agent. Implementation of the high performance communication system is described in thispaper. It is a gateway system integrating a PBX and a VoIP module. All components that H.323 defined tosupport VoIP are implemented in the VoIP module, currently in a simplified manner. As an embeddedsystem, it features realtimeness and task distributiveness. A number of additional techniques are used toimprove the communication performance, including noise suppression, zero copy, and buffer structureoptimization. When integrated and refined in interoperability, the system will readily serve as a product.Keywords VoIP, gateway, gatekeeper, communication common platform, embedded system, voiceprocessing, H.323.1

Xicheng Liu; Timothy J. Li

326

In situ powder X-ray diffraction, synthesis, and magnetic properties of the defect zircon structure ScVO(4-x).  

Science.gov (United States)

We report the formation pathway of ScVO(4) zircon from ScVO(3) bixbyite with emphasis on the synthesis and stability of the novel intermediate defect zircon phase ScVO(4-x) (0.0 bulk magnetic susceptibility data as well as (45)Sc and (51)V solid state NMR spectroscopy. ScVO(4-x) can only be obtained by oxidation of ScVO(3) or ScVO(3.5+y) while the reduction of ScVO(4) does not yield the novel defect structure. Mechanistic insights into the oxidative formation of ScVO(4) via the defect structure are presented. PMID:19894769

Shafi, Shahid P; Kotyk, Matthew W; Cranswick, Lachlan M D; Michaelis, Vladimir K; Kroeker, Scott; Bieringer, Mario

2009-11-16

327

Prepaid and Postpaid VoIP Service Enhancements and Hybrid Network Performance Measurement  

Directory of Open Access Journals (Sweden)

Full Text Available This study focuses on prepaid and postpaid VoIP technology service enhancement. The aims are to i) merge wireless technology in rural areas with wired technologies and services in urban areas. It intends to investigate the minimum requirement needs by wireless and wired technology in using of telco connectivity. It is also to define which technology will achieve a low operating cost and good performance. In addition, the most apparent benefit of implementing prepaid/postpaid VoIP network in rural areas is that to achieve a robust fault tolerance and load-balancing voice traffic between urban and rural areas. ii) Merging of WAP and VoIP network to provide Information-on-Demand (IoD) services to prepaid and postpaid VoIP users. It is to provide value added services for prepaid and postpaid VoIP users. WAP and other similar technologies will continue to play an important role in the development of Information-on-Demand (IoD) services in future. In addition, the most apparent benefit of implementing WAP technology with prepaid/postpaid VoIP network architecture is that to achieve WAP enabled mobile to access this facility during travelling, meeting, seminar and conference. Integration of WAP technology with prepaid/postpaid VoIP network architecture can achieve efficiency end-to-end information services between service providers (ISPs/ITSPs) and WAP mobile phone users. Therefore, prepaid and postpaid VoIP service enhancement can improve and obtain high efficiency network, technical, business and customer-care aspects in contributing the robust prepaid/postpaid VoIP network architecture for prepaid/postpaid VoIP users.

Mohd Nazri Ismail; Asaad Abusin

2006-01-01

328

Time limit and time at VO2max' during a continuous and an intermittent run.  

UK PubMed Central (United Kingdom)

BACKGROUND: The purpose of this study was to verify, by track field tests, whether sub-elite runners (n=15) could (i) reach their VO2max while running at v50%delta, i.e. midway between the speed associated with lactate threshold (vLAT) and that associated with maximal aerobic power (vVO2max), and (ii) if an intermittent exercise provokes a maximal and/or supra maximal oxygen consumption longer than a continuous one. METHODS: Within three days, subjects underwent a multistage incremental test during which their vVO2max and vLAT were determined; they then performed two additional testing sessions, where continuous and intermittent running exercises at v50%delta were performed up to exhaustion. Subject's gas exchange and heart rate were continuously recorded by means of a telemetric apparatus. Blood samples were taken from fingertip and analysed for blood lactate concentration. RESULTS: In the continuous and the intermittent tests peak VO2 exceeded VO2max values, as determined during the incremental test. However in the intermittent exercise, peak VO2, time to exhaustion and time at VO2max reached significantly higher values, while blood lactate accumulation showed significantly lower values than in the continuous one. CONCLUSIONS: The v50%delta is sufficient to stimulate VO2max in both intermittent and continuous running. The intermittent exercise results better than the continuous one in increasing maximal aerobic power, allowing longer time at VO2max and obtaining higher peak VO2 with lower lactate accumulation.

Demarie S; Koralsztein JP; Billat V

2000-06-01

329

Variación estacional y vertical de la biomasa del macrozooplancton en la bahía de Mochima, Estado Sucre - Venezuela, durante 1997 - 1998/ Seasonal and vertical variation of macrozooplankton biomass in the Mochima Bay, Sucre State, Venezuela, during 1997 - 1998  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El papel del macrozooplancton en la bahía de Mochima fue determinado cuantitativamente mediante su biomasa y su relación con algunos parámetros ambientales durante 1997 y 1998. Se midió la transparencia del agua con un disco de Secchi; las muestras de agua fueron recolectadas con una botella Niskin (5 L) para determinar: temperatura, oxígeno disuelto y biomasa fitoplanctónica en dos estaciones. Las muestras de macrozooplancton fueron recolectadas por medio de calado (more) s oblicuos, con una malla estándar (555 ?m y 0,25 m de diámetro de boca) entre 0-5 y 10-15 m, en dos estaciones, una externa (Est. A) y otra interna (Est. B). La biomasa se estimó en términos del volumen desplazado y del peso seco. Los períodos de máxima biomasa macrozooplanctónica se registraron entre marzo-mayo y octubre-diciembre para ambos años; los mínimos ocurrieron en julio-septiembre. La mayor abundancia se detectó en la estación interna y en la capa profunda (10-15 m). Los máximos valores de la biomasa de fito y macrozooplancton coincidieron con períodos de mayor intensidad de la surgencia costera e intensidad del viento. Estos valores fueron más altos en 1997 que en 1998. El patrón estacional de la biomasa planctónica es similar al señalado para la zona. Sin embargo, se demuestra la existencia de una alta variabilidad anual en el crecimiento del fito y del macrozooplancton Abstract in english The role of macrozooplankton in Mochima Bay was studied examining its biomass and its relationships with some environmental parameters during 1997 and 1998. Water transparency was measured with a Secchi disk; water samples were collected with a Niskin bottle (5 L) to determine: temperature, dissolved oxygen and phytoplankton biomass in two stations. Macrozooplankton horizontal samples were collected with a net (mesh size 555 ?m and 0.25 m in diameter) at 0-5 and 10-1 (more) 5 m in two stations, one external (Est. A) and other internal (Est. B). Macrozooplankton biomass was estimated in terms of displaced volume and dry weight. The periods of maximum macrozooplankton biomass occurred between March-May and October-December for both years; the minima occurred in July-September. The highest biomass values were measured at the inner station and in the deeper layer (10-15 m). Maximum values for phytoplankton and macrozooplankton biomass coincided with periods of higher upwelling and wind intensity; these values were higher in 1997 than in 1998. The results follow pre-established patterns but also show high annual variability in phytoplankton and zooplankton biomass

Márquez, Brightdoom; Baumar, Marín; Díaz-Ramos, José Rafael; Troccoli, Luis; Subero-Pino, Sonia

2007-12-01

330

E-LEARNING - INNOVATIONS IN EDUCATION OF NURSES / E-learning - inovácie vo vzdelávaní sestier  

Directory of Open Access Journals (Sweden)

Full Text Available The present requirements in nursing education lead educational institutions to preparation of the flexible forms of education, in full-time or part-time study. One of the main objectives of the university education of nurses is to provide available and relevant education for the applicants for the chosen profession to improve the personal and professional quality. In 2008/2009 the Department of Nursing at Faculty of Social Sciences and Health Care, Constantine the Philosopher University in Nitra, provides the distant form of education in applied fields of nursing through the on-line courses.Sú?asné požiadavky vo vzdelávaní sestier vedú vzdelávacie inštitúcie k príprave flexibilných foriem vzdelávania, ?i už v internom alebo externom štúdiu. K hlavným cie?om vysokoškolského vzdelávania sestier patrí poskytnutie dostupného a relevantného vzdelávania záujemcom pre danú profesiu, k preh?beniu osobných a profesionálnych kvalít. V akademickom roku 2008/2009 na Katedre ošetrovate?stva Fakulty sociálnych vied a zdravotníctva UKF v Nitre realizujeme dištan?nú formu vzdelávania v aplikovaných odborov ošetrovate?stva prostredníctvom on-line kurzov.

Solgajová Andrea; Mesárošová Jozefína

2008-01-01

331

Estimation of VO2max from the ratio between HRmax and HRrest - the Heart Rate Ratio Method.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effects of training and/or ageing upon maximal oxygen uptake ( VO(2max)) and heart rate values at rest (HR(rest)) and maximal exercise (HR(max)), respectively, suggest a relationship between VO(2max) and the HR(max)-to-HR(rest) ratio which may be of use for indirect testing of VO(2max). Fick pri...

Uth, Niels; Sørensen, Henrik; Overgaard, Kristian; Pedersen, Preben K

332

76 FR 59916 - Interconnected VoIP Service; Wireless E911 Location Accuracy Requirements; E911 Requirements for...  

Science.gov (United States)

...05-196; FCC 11-107] Interconnected VoIP Service; Wireless E911 Location Accuracy...rules requiring providers of interconnected VoIP service to supply E911 capabilities to...service. The rules adopted in the 2005 VoIP 911 Order apply only to providers of...

2011-09-28

333

A structured approach to VO reconfigurations through Policies  

CERN Document Server

One of the strength of Virtual Organisations is their ability to dynamically and rapidly adapt in response to changing environmental conditions. Dynamic adaptability has been studied in other system areas as well and system management through policies has crystallized itself as a very prominent solution in system and network administration. However, these areas are often concerned with very low-level technical aspects. Previous work on the APPEL policy language has been aimed at dynamically adapting system behaviour to satisfy end-user demands and - as part of STPOWLA - APPEL was used to adapt workflow instances at runtime. In this paper we explore how the ideas of APPEL and STPOWLA can be extended from workflows to the wider scope of Virtual Organisations. We will use a Travel Booking VO as example.

Reiff-Marganiec, Stephan

2012-01-01

334

Zircon to monazite phase transition in CeVO4  

CERN Document Server

X-ray diffraction and Raman-scattering measurements on cerium vanadate have been performed up to 12 and 16 GPa, respectively. Experiments reveal that at 5.3 GPa the onset of a pressure-induced irreversible phase transition from the zircon to the monazite structure. Beyond this pressure, diffraction peaks and Raman-active modes of the monazite phase are measured. The zircon to monazite transition in CeVO4 is distinctive among the other rare-earth orthovanadates. We also observed softening of external translational Eg and internal B2g bending modes. We attributed it to mechanical instabilities of zircon phase against the pressure-induced distortion. We additionally report lattice-dynamical and total-energy calculations which are in agreement with the experimental results. Finally, the effect of non-hydrostatic stresses on the structural sequence is studied and the equations of state of different phases are reported.

Panchal, V; Santamaria-Perez, D; Errandonea, D; Manjon, F J; Rodriguez-Hernandez, P; Munoz, A; Achary, S N; Tyagi, A K

2011-01-01

335

Magnetic and transport properties of vanadate PrVO3  

International Nuclear Information System (INIS)

The magnetic and electric properties of the vanadate PrVO3 with the GdFeO3-type orthorhombic structure are reported. The temperature-dependent magnetization displays an obvious irreversibility under zero-field cooling (ZFC) and field cooling (FC), and two magnetic phase-transition temperatures 20 K and 90 K, which may correspond to the spin reorientation and the magnetic ordering, respectively. A canted antiferromagnetic configuration is derived from the low spontaneous magnetization at 5 K. In the sintered bulk, a high coercivity 2.4 T is due to the pinning of the domain wall. The resistance measurement shows that the compound is an insulator at low temperatures. (author)

2000-04-03

336

A Perceptual Quality Model for Adaptive VoIP Applications  

UK PubMed Central (United Kingdom)

Quality models predict the perceptual quality of services as they calculate subjective ratings from measured parameters. In this paper we present a new quality model that evaluates VoIP telephone calls in order to control their transmission at run-time. In addition to packet loss rate, coding mode and delay it takes into account the impairments due to changes in the transmission conguration (e.g. switching the coding mode or re-scheduling the playout time). It is also computation efficient and open source. To demonstrate its potential, we apply our model to select the ideal coding and packet rate in bandwidth limited environments. Furthermore we decide, based on model predictions, whether to delay the playout of speech frames after delay spikes. Delay spikes often occur after congestion and cause packets to arrive too late. We show a considerable improvement in perceptual speech quality if our model is applied.

Christian Hoene; Holger Karl; Adam Wolisz

337

Evaluation of the American College of Sports Medicine submaximal treadmill running test for predicting VO2max.  

UK PubMed Central (United Kingdom)

The purpose of this study was to assess the validity of the American College of Sports Medicine's (ACSM's) submaximal treadmill running test in predicting VO2max. Twenty-one moderately well-trained men aged 18-34 years performed 1 maximal treadmill test to determine maximal oxygen uptake (M VO2max) and 2 submaximal treadmill tests using 4 stages of continuous submaximal exercise. Estimated VO2max was predicted by extrapolation to age-predicted maximal heart rate (HRmax) and calculated in 2 ways: using data from all submaximal stages between 110 b·min(-1) and 85% HRmax (P VO2max-All), and using data from the last 2 stages only (P VO2max-2). The measured VO2max was overestimated by 3% on average for the group but was not significantly different to predicted VO2max (1-way analysis of variance [ANOVA] p = 0.695; M VO2max = 53.01 ± 5.38; P VO2max-All = 54.27 ± 7.16; P VO2max-2 = 54.99 ± 7.69 ml·kg(-1)·min(-1)), although M VO2max was not overestimated in all the participants--it was underestimated in 30% of observations. Pearson's correlation, standard error of estimate (SEE), and total error (E) between measured and predicted VO2max were r = 0.646, 4.35, 4.08 ml·kg(-1)·min(-1) (P VO2max-All) and r = 0.642, 4.21, 3.98 ml·kg(-1)·min(-1) (P VO2max-2) indicating that the accuracy in prediction (error) was very similar whether using P VO2max-All or P VO2max-2, with up to 70% of the participants predicted scores within 1 SEE (?4 ml·kg(-1)·min(-1)) of M VO2max. In conclusion, the ACSM equation provides a reasonably good estimation of VO2max with no difference in predictive accuracy between P VO2max-2 and P VO2max-All, and hence, either approach may be equally useful in tracking an individual's aerobic fitness over time. However, if a precise knowledge of VO2max is required, then it is recommended that this be measured directly.

Marsh CE

2012-02-01

338

Variação diurna e resposta da cinética do VO2 de ciclistas durante exercício muito intenso Diurnal variation and Vo2 kinetic response of cyclists during heavy exercis e  

Directory of Open Access Journals (Sweden)

Full Text Available O objetivo do presente estudo foi avaliar a influência da hora do dia nos parâmetros da cinética do consumo de oxigênio de ciclistas durante exercício muito intenso. Nove voluntários do sexo masculino realizaram exercícios de carga constante às 08:00, 13:00 e 18:00 h, em dias diferentes. Estes exercícios foram realizados duas vezes em cada visita, com um intervalo de 1 h entre eles. A intensidade usada foi de 75%? (75% da diferença entre o VO2 no limiar de lactato e o VO2max. A amplitude do componente primário do VO2 (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 e 2609 ± 370 ml.min-1), a constante de tempo do componente primário do VO2 (19.3 ± 2.5 s, 18.4 ± 3.0 s e 19.7 ± 3.9 s), o componente lento do VO2 (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 e 680 ± 121 ml.min-1) e o tempo de resposta média (51.8 ± 4.2 s, 51.2 ± 4.2 s e 51.4 ± 3.4 s) não apresentaram diferenças significativas entre os diferentes horários do dia (08:00, 13:00 e 18:00 h), assim como os demais parâmetros da cinética do VO2. Estes resultados sugerem que a resposta da cinética do VO2 de ciclistas durante exercício muito intenso (75%?) não é influenciada pela hora do dia.The objective of the present study was to evaluate the influence of the time of day on the parameters of oxygen uptake kinetics of trained cyclists during high intensity exercise. Nine male volunteers repeated bouts at constant loads at 08:00, 13:00 and 18:00 h on different days. These exercise bouts were performed twice on each occasion, with an interval of 1 h between them. The load intensity used was 75%? (75% of the difference between the VO2 at the lactate threshold and the VO2max). The primary VO2 amplitude (2597 ± 273 ml.min-1, 2513 ± 268 ml.min-1 and 2609 ± 370 ml.min-1), the primary VO2 time constant (19.3 ± 2.5 s, 18.4 ± 3.0 s and 19.7 ± 3.9 s), the VO2 slow component (735 ± 81 ml.min-1, 764 ± 99 ml.min-1 and 680 ± 121 ml.min-1) and the mean response time (51.8 ± 4.2 s, 51.2 ± 4.2 s and 51.4 ± 3.4 s) did not present significant differences at the different times (08:00, 13:00 and 18:00 h), neither did the other parameters of the VO2 kinetics. These results suggest that the response of the VO2 kinetics of cyclists exercising at high intensity (75%?) is not influenced by the time of day.

Marcos G. Santana; Sergio Tufik; Giselle S. Passos; Donald M. Santee; Benedito S. Denadai; Marco T. Mello

2008-01-01

339

EPR and UV studies of VO2+ ions in potassium D-gluconate monohydrate single crystals  

International Nuclear Information System (INIS)

Electron paramagnetic resonance (EPR) of VO2+ doped potassium hydrogen D-gluconate single crystals and powder have been examined at room temperature. Single crystal rotations in each of the three mutually orthogonal crystalline planes namely ac, ba and ca indicate two different VO2+ complexes. Each complex is located in different chemical environments, each environment containing two magnetically inequivalent VO2+ sites in distinct orientations occupying substitutional positions in the lattice and showing a very large angular dependence. The powder spectrum also clearly indicates four different VO2+ complexes, confirming the single crystal analysis. Crystalline field around the VO2+ ion is nearly axial. The optical absorption spectrum of VO2+ ions in the crystal lattice is also studied at room temperature. The characteristic spectrum of the VO2+ ions has two absorption bonds. The bond positions are at 17 857 and 11 235 cm-1. Spin Hamiltonian parameters and molecular orbital coefficients are calculated from the EPR and the optical data, and results are discussed.

2009-11-01

340

Experimental Analysis of VoIP over Wireless Local Area Networks  

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Full Text Available VoIP is a rapidly growing technology that enables the transport of voice over data networks such asthe public Internet. VoIP became a viable alternative to the public switched telephone networks (PSTNs). In parallel, a dramatic increase is happening in the deployment of Wireless Local Areas Networks (WLAN) in buildings and corporate campuses. Nowadays, WLAN is mostly used for ordinary data services such as web browsing, file transfer and electronic mail. However, with the emerging usage of VoIP telephony, WLAN are sought to be used as an access infrastructure for enabling such applications. One of the issues of using VoIP over WLAN is the effects caused by users roaming within and between WLAN subnets during a VoIP session. The latency and the jitter are greatly impacted when the control of the mobile node is handed over from one access point (AP) to another one. This poses a challenge to providing and preserving QoS for VoIP users in WLAN environments. In this paper, we propose to study and measure the effect of the handover for both intra and inter mobility for VoIP traffic.

Abderrahmane Lakas; Mohammed Boulmalf

2007-01-01

 
 
 
 
341

Electrochemical lithium intercalation in VO{sub 2}(B) in aqueous electrolytes  

Energy Technology Data Exchange (ETDEWEB)

Electrochemical lithium intercalation in VO{sub 2}(B) electrodes in aqueous electrolytes has been studied by means of electrochemical methods (such as cyclic voltammetry and constant current discharge and charge) as well as atomic absorption spectrophotometry. Experiments were conducted in various buffer electrolytes having a range of pH from 6.0 to 11.3. Voltammetry clearly reveals current peaks related to lithium intercalation and deintercalation in the whole pH range investigated. Electrolyte pH plays a very important role in the performance of VO{sub 2}(B) electrodes. When pH is higher than about 10, the capacity involved in the lithium intercalation in VO{sub 2}(B) electrodes shows a rapid decline with repetitive cycling, which is suggested to be the result of the dissolution of the VO{sub 2}(B) electrodes into the bulk electrolytes. Decreasing the pH tends to reduce the dissolution of VO{sub 2}(B) and thereby gives better cycling behavior of VO{sub 2}(B) electrodes. On the other hand, it also leads to increased hydrogen evolution that might affect the lithium intercalation reaction. Thus, the optimum pH range for the lithium intercalation reaction is found to be between 8 and 10. VO{sub 2}(B) electrodes cycled in this pH range demonstrate very good capacity retention.

Zhang, M.; Dahn, J.R. [Simon Fraser Univ., Burnaby, British Columbia (Canada). Dept. of Physics

1996-09-01

342

VO2max Trainability and High Intensity Interval Training in Humans: A Meta-Analysis.  

Science.gov (United States)

Endurance exercise training studies frequently show modest changes in VO2max with training and very limited responses in some subjects. By contrast, studies using interval training (IT) or combined IT and continuous training (CT) have reported mean increases in VO2max of up to ?1.0 L · min(-1). This raises questions about the role of exercise intensity and the trainability of VO2max. To address this topic we analyzed IT and IT/CT studies published in English from 1965-2012. Inclusion criteria were: 1)?3 healthy sedentary/recreationally active humans random effects model. The summary statistic of interest was the change in VO2max. A total of 334 subjects (120 women) from 37 studies were identified. Participants were grouped into 40 distinct training groups, so the unit of analysis was 40 rather than 37. An increase in VO2max of 0.51 L ·min(-1) (95% CI: 0.43 to 0.60 L · min(-1)) was observed. A subset of 9 studies, with 72 subjects, that featured longer intervals showed even larger (?0.8-0.9 L · min(-1)) changes in VO2max with evidence of a marked response in all subjects. These results suggest that ideas about trainability and VO2max should be further evaluated with standardized IT or IT/CT training programs. PMID:24066036

Bacon, Andrew P; Carter, Rickey E; Ogle, Eric A; Joyner, Michael J

2013-09-16

343

Structural, photophysical and photocatalytic properties of novel Bi2AlVO7  

International Nuclear Information System (INIS)

Bi2AlVO7 was prepared by solid-state reaction technique for the first time and the structural and photocatalytic properties of Bi2AlVO7 and Bi2InTaO7 were investigated. The results showed that Bi2AlVO7 crystallized in the tetragonal crystal system with space group I4/mmm. In addition, the band gaps of Bi2AlVO7 and Bi2InTaO7 were estimated to be about 2.06 and 2.81 eV. The photocatalytic degradation of aqueous methylene blue (MB) dye with Bi2AlVO7 or Bi2InTaO7 as catalyst was investigated under visible light irradiation. Bi2AlVO7 showed higher photocatalytic activity compared with Bi2InTaO7 for photocatalytic degradation of MB under visible light irradiation. Complete removal of aqueous MB dye was realized after visible light irradiation for 160 min with Bi2AlVO7 as the photocatalyst. The reduction of the total organic carbon (TOC) and the formation of inorganic products, SO42- and NO3- revealed the continuous mineralization of aqueous MB dye during the photocatalytic process. The possible photocatalytic degradation pathway of aqueous MB dye was revealed under visible light irradiation.

2009-05-30

344

Size-dependent magnetic properties of VO2 nanocrystals dispersed in a silica matrix  

International Nuclear Information System (INIS)

Magnetic nanocrystalline VO2 particles have been successfully synthesized in a silica glass matrix by the sol-gel method at calcination temperatures of 700 0C and above. The presence of small quantities of diamagnetic V2O5 nanocrystals in glass samples calcined at ?800 0C has been confirmed. The thermal behavior of magnetization (zero-field-cooled and field-cooled) and magnetic hysteresis of VO2 nanocrystals in the 10-300 K temperature interval have demonstrated that the VO2 nanocrystals present in these glasses display superparamagnetic-ferromagnetic transition at low temperatures. X-band electron paramagnetic resonance (EPR) spectra of VO2 nanoparticles have depicted broad symmetric lines [?Hpp?104 mT at room temperature (RT) and 250 mT at liquid nitrogen temperature (LNT)]. The increase in EPR line intensity on going from RT to LNT suggests that VO2 nanocrystals have undergone ferromagnetic-like ordering in the temperature interval RT-77 K. The presence of small numbers of isolated VO2+ ions in the SiO2 matrix has also been confirmed from EPR studies. From EPR and optical spectral studies it has been shown that the VO2+ ion has square pyramidal conformation with tetragonal compression having C4v symmetry. It is established that the in-plane ? bonding and out-of-plane ? bonding are predominantly ionic in nature.

2008-06-25

345

BiVO4–graphene catalyst and its high photocatalytic performance under visible light irradiation  

International Nuclear Information System (INIS)

Highlights: ? A facile strategy is designed to deposit leaf-like BiVO4 lamellas on graphene sheet. ? Graphene oxide is reduced to graphene in the hydrothermal reaction process. ? BiVO4–graphene system shows high catalytic effects under visible light irradiation. - Abstract: A BiVO4–graphene photocatalyst was prepared by a facile one-step hydrothermal method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM) techniques. The results show that the graphene sheets in this catalyst are exfoliated and decorated by leaf-like BiVO4 lamellas. In comparison with the pure BiVO4 catalyst, the BiVO4–graphene system reveals much higher photocatalytic activity for degradation of methyl orange (MO), methylene blue (MB), Rhodamine B (RhB) and active black BL-G in water under visible light irradiation due to the concerted effects of BiVO4 and graphene sheets or their integrated properties.

2011-12-15

346

Estrategias de crecimiento y distribución de biomasa en Pinus pseudostrobus bajo diferentes condiciones de competencia/ Growth strategies and biomass distribution in Pinus pseudostrobus under different conditions of competition  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La intensidad de competencia en la que se desarrollan los individuos es un factor importante en la supervivencia, producción de biomasa y estrategia del crecimiento de la planta (arquitectura), características que interaccionan con su genotipo. En el presente estudio se evaluó el efecto de niveles de competencia en 13 familias juveniles de medios hermanos de Pinus pseudostrobus Lindl., sobre su supervivencia, producción y distribución de biomasa. Se compararon las co (more) ndiciones: (I) baja densidad (0.25 x 0.12 m) con múltiples familias aleatorizadas (inter-familiar), (II) alta densidad (0.12 x 0.06 m) con grupos inter-familiares, y (III) alta densidad (0.12 x 0.06 m) con parcelas monofamiliares (intra-familiar), establecidas en un ensayo de jardín común bajo un diseño de parcelas divididas con cuatro repeticiones y cuatro individuos por familia. A 10 meses de establecido el ensayo se cosecharon dos repeticiones. Se detectaron diferencias entre condiciones de competencia (P ?0.05) para todas las variables evaluadas de producción, distribución de biomasa, supervivencia y arquitectura de crecimiento. A nivel de familia se identificaron estrategias en el crecimiento de los individuos semejantes a los tres comportamientos clásicos de arquetipos (de aislamiento, de competencia y de cultivo), así como genotipos que pudieron ajustar su crecimiento en función del ambiente de competencia. Los resultados obtenidos reflejan la importancia de la selección de ambientes y de genotipos para aumentar su adaptación y productividad en los programas de mejoramiento. Abstract in english Competition intensity at which individual plants grow is an important factor in their survival, biomass production and architecture; characteristics that interact with their genotype. In this study, we evaluated the effect of different levels of competition in 13 juvenile families of Pinus pseudostrobus Lindl. half-siblings in terms of plant survival, growth and biomass distribution. The conditions compared were (I) randomized multiple families (inter-family) planted at l (more) ow density (0.25 x 0.12 m), (II) inter-family groups at high density (0.12 x 0.06 m), and (III) single-family parcels (intra-family) at high density (0.12 x 0.06 m), established in a common garden test under a split plot design with four replicates and four plants per replicate. At 10 months of being established, two replicates were harvested. Differences were detected between competitive conditions for all measured variables on production, biomass distribution, survival and growth architecture (P ? 0.05). At family level we identified individual growth strategies which resemble the three classic ideotypes (isolation, competition and crop), as well as genotypes that adjusted their growth depending on the competitive environment. These results reflect the importance of environmental and genotype selection in order to increase adaptation and productivity at breeding programs.

Cambrón Sandoval, Víctor H.; Suzán Azpiri, Humberto; Vargas Hernández, J. Jesús; Sánchez Vargas, Nahum M.; Sáenz-Romero, Cuauhtémoc

2013-03-01

347

Preparation of Co-BiVO4 Photocatalyst and Its Application in the Photocatalytic Oxidative Thiophene  

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Full Text Available The Co-BiVO4 photocatalyst was prepared by hydrothermal method and characterized by X-ray diffraction, scanning electron microscope, UV-Vis absorption spectroscope, and low-temperature N2 adsorption. The characterized results indicate that highly crystalline monoclinic scheelite structure of Co-BiVO4 is obtained at pH=7 and the Co dopant does not change the crystal phase of BiVO4. The Co-BiVO4 has a significant red-shift in the absorption band in the visible region, and its absorption intensity increases greatly for the doped catalyst compared with pure BiVO4. Low-temperature N2 adsorption result reveals that the pore size of the Cu-BiVO4(pH=7) mostly distributes at 2.67 nm. The desulfurization ability of Co-BiVO4 was researched by photocatalytic oxidation of thiophene in visible light. The results show that the Co-BiVO4 photocatalysts exhibit higher photocatalytic activities for degradation of thiophene under visible light irradiation. When pH value is 7.0 and the hydrothermal synthesize time is 8 h, the photocatalytic activities reach the maximum. Under the conditions of 150 mL/min air flow, 1.0 mg/L catalyst amount, and visible light irradiation for 3 h in 400 W xenon lamp light, the desulfurization rate by Co-BiVO4 at 600 mg/L initial concentration increases to 86%.

GAO Xiao-Ming, FU Feng, WU Yu-Fei, ZHANG Li-Ping, LI Wen-Hong

2012-01-01

348

Tolerancia de plantas de feijoa (Acca sellowiana [Berg] Burret) a la salinidad por NaCl  

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Full Text Available Los efectos de la salinidad por NaCl sobre la producción y la distribución de la biomasa, la toma de agua y el área foliar total fueron investigados en plantas de feijoa (Acca sellowiana [Berg] Burret) cultivadas en materas con suelo bajo condiciones de invernadero, durante ocho meses. Los tratamientos con la sal comenzaron 60 d después del transplante. El NaCl fue agregado en diferentes concentraciones: 0, 20, 40, 60, 80 mM de NaCl en el suelo. Estas concentraciones correspondieron a conductividades eléctricas de 2,8; 4,6; 6,1; 8,4 y 11,1 dS· m-1, respectivamente. Para evitar el choque osmótico, el tratamiento salino fue impuesto progresivamente, aumentando la concentración de sal cada semana hasta alcanzar la concentración final. Las materas se regaron dos veces por semana y se evitó el exceso del agua. El incremento en la salinidad tuvo poca o ninguna influencia sobre la producción y distribución de la biomasa, pero disminuyó la evapotranspiración de las plantas. El agua evapotranspirada se redujo considerablemente a medida que la salinidad fue aumentada en el suelo. Los resultados sugieren que las plantas de feijoa muestran tolerancia a la salinidad bajo condiciones de invernadero.

Casierra-Posada Fánor Ernesto; Rodríguez Sandra Yaqueline

2006-01-01

349

Efecto de aportes superficiales de biomasa vegetal en la temperatura, humedad y dinámica de nemátodos en el suelo en época seca en Santander de Quilichao (Departamento del Cauca). Efecto de aportes superficiales de biomasa vegetal en la temperatura, humedad y dinámica de nemátodos en el suelo en época seca en Santander de Quilichao (Departamento del Cauca)  

Directory of Open Access Journals (Sweden)

Full Text Available Effect of superficial contributions of vegetal biomass in the temperature, humidity and dynamics of nematodes in the soil at a season dry time in Santander Quilichao (Department of the Cauca). In the experimental station at CIAT (Santander de Quilichao- Cauca, to 3°06'N and 76°31'W), the effect of surface application of vegetal biomass was explored (6 t dm ha-1 semester-1), after planting of bean. The experiment consisted of four treatments, three cover of the trees that had contrasting characteristics (Calliandra-CAL; Cratylia-CRA and Tithonia - TTH) and the control- CON; arranged in a CBRD with 5 repetitions. The evaluated variables were: environmental (humidity and temperature of the soil) and biological (abundance and dynamics of the nematodes). Under cover the humidity in a 3% was increased and the soil temperature was regulated from the 0.4 to 0.6°C smaller than the CON treatment. The behavior of the nematodes was very dynamic and was related to the environmental conditions, being favored at wet seasons and by the dynamics of decomposition related to the type of material. In general, the cover modified the microenvironment affecting the population of organisms, generating changes in the aireation, structures and nutrients cycling in the soil by contribution of organic matter through mulch which regule its availability in the productive systems. Palabras claves: Suelo, cobertura arbórea, nemátodos, biomasa, factores ambientales.En la estación experimental del CIAT (Santander de Quilichao- Cauca, 3°06'N y 76°31'W) se exploró el efecto de aplicaciones superficiales de biomasa vegetal (6 t ms ha-1 semestre-1), después de la siembra de fríjol. El ensayo constó de cuatro tratamientos, tres coberturas de árboles de características contrastantes (Calliandra-CAL; Cratylia-CRA y Tithonia -TTH) y el testigo CON; dispuestos en un DBCA con 5 repeticiones. Las variables evaluadas fueron ambientales (humedad y temperatura del suelo) y biológicas (abundancia y dinámica de los nemátodos). Bajo cobertura se incrementó la hu­medad en 3% y se reguló la temperatura del suelo de 0.4 a 0.6°C menor que CON. El comportamiento de los nemátodos fue muy dinámico y estuvo relacionado con las condiciones ambientales, siendo favorecido en épocas de humedad y por la dinámica de descomposición relacionada con el tipo de material. En general, la cobertura modificó el microambiente afectando la población de organismos, generando cambios en la aireación, estructura y ciclaje de nutrientes en el suelo por aporte de materia orgánica a través de la hojarasca regulando su disponibilidad en los sistemas productivos.Palabras claves: Suelo, cobertura arbórea, nemátodos, biomasa, factores ambientales.

Navia Estrada Jorge Fernando; Barrios Edmundo; Sánchez Marina

2006-01-01

350

Contenido de carbono y nitrógeno de la biomasa microbiana en suelos de La Habana/ Microbial biomass carbon and nitrogen content in Havana Soil  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish La presente investigación fue diseñada con el objetivo de calcular el carbono (C) y el nitrógeno (N) inmovilizado en la biomasa microbiana de cuatro suelos Ferralíticos Rojos de la Provincia de La Habana, Cuba, empleando la metodología de “fumigación extracción” en el año 2006. Se colectaron muestras de cuatro sitios (Bainoa, La Salud, Quivicán y Guanajay), los cuales mostraron diferencias en las características físico - químicas, incluyendo difere (more) ncias en contenido de materia orgánica entre 2,8 y 5%. La sensibilidad de las metodologías empleadas fue valorada utilizando el error estándar de las medias como parámetro estadístico. Los niveles de C inmovilizados en la biomasa microbiana en los suelos estudiados, variaron entre 289 y 425 ?g/g de suelo y tuvieron una correlación altamente significativa con el contenido de materia orgánica del suelo. Los contenidos de N inmovilizados variaron entre 62 y 90 ?g/g de suelo y se observó también una correlación significativa entre este parámetro y el contenido de nitrógeno total. El error estándar de la media para las determinaciones del C microbiano varió entre 2 y 16 y fueron ligeramente superiores a lo hallado en reportes anteriores; mientras que los errores observados en las determinaciones del N microbiano se mantuvieron entre los rangos considerados adecuados. Finalmente la metodología fue adaptada a las condiciones del laboratorio. Abstract in english This research was carried out to calculate the microbial biomass carbon and nitrogen content in Red Ferralitic Soils from the Havana province, using the “fumigation and extraction” method. For this work soil samples were taken from four different sites (Bainoa, La Salud, Quivicán and Guanajay) with different physicalchemical characteristics, including organic matter content which ranged from 2.8 and 5%. The sensibility of the methods employed was asssessed us (more) ing the mean standard error as statistical parameter. The C content in soil microbial biomass ranged from 289 and 425 ?g/g of soil (289 - 425 mg/kg of soil) and had it a significant correlation by soil organic matter content. On the other hand, N content in soil microbial biomass ranged from 62 and 90 ?g/g of soil (62-90 mg/kg of soil), and had it a significant correlation by soil nitrogen content. The mean standard error of microbial C determinations ranged from 2 and 16, being slightly superior to previous reports, while the mean standard error of the microbial N determinations were among adequate limits. Finally, this methodology was adapted to laboratory conditions.

Gómez-Jorrin, Luís A.; Morales-Valdes, Amalia; Dueñas-Vega, Graciela; Dantin-Martínez, Juana María; Chávez-Gonzalez, Nereida; Torres-Leblanch, Maite

2012-06-01

351

Reservas de biomasa de árboles dispersos en potreros y mitigación al cambio climático/ The contribution of dispersed trees in pastures for biomass reserve and climate change mitigati  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish El presente estudio tuvo como objetivo determinar la contribución de los árboles en potreros a la mitigación al cambio climático mediante la estimación de las reservas de carbono in Costa Rica y Nicaragua. Entre los años 2002 y 2003, 17 783 árboles fueron inventariados en potreros de 59 fincas ubicadas en zonas de bosque tropical seco, húmedo y seco con transición a húmedo. El valor promedio de las reservas de biomasa de los árboles en los potreros fue de 10,7? (more) ?1,1 Mg/ha con un valor mínimo de 5,3±1 Mg/ha en Rivas y un máximo de 13,5±3,5 Mg/ha en Matiguás. Existe relación entre la biomasa arriba del suelo de los potreros con la densidad árboles y el área basal, lo que permitió desarrollar ecuaciones simples para predecir dichos cambios. El diseño de políticas que incentiven la conservación y manejo de árboles en potreros, será un aspecto clave a ser incorporado dentro de las estrategias de cambio climático de los países. Abstract in english This study aimed to explore the contribution of trees in pastures to climate change mitigation by estimating tree biomass stocks (carbon) in Costa Rica and Nicaragua. Between 2002 and 2003, 17,783 trees were inventoried in pastures of 59 farms located in areas representing three life zones: tropical dry forest, tropical wet forest and transition from tropical dry to tropical wet forest. The average value of biomass stocks of trees in pastures was 10.7 ± 1.1 Mg/ha with a (more) minimum value of 5.3 ± 1 Mg/ha in Rivas and a maximum of 13.5 ± 3.5 Mg/ha in Matiguás. There is a relationship between aboveground biomass in the pastureland, tree density and basal area, which allows the development of simple equations. The design of policies that encourage the conservation and management of trees in pastures will be a key aspect to be incorporated into national climate change strategies.

Chacón-León, Mario; Harvey, Celia Alice

2013-06-01

352

DENSIDAD Y BIOMASA DE MACROINVERTEBRADOS ACUÁTICOS DERIVANTES EN UNA QUEBRADA TROPICAL DE MONTAÑA (BOGOTÁ, COLOMBIA) Density and biomass of drifting aquatic macroinvertebrates in a tropical mountain creek at Bogotá, Colombia  

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Full Text Available Se estimó la variación en la densidad de deriva de macroinvertebrados acuáticos y su aporte de materia orgánica en términos de biomasa de diferentes estados inmaduros e imagos, en un tramo de una quebrada tropical de montaña ubicada en los cerros orientales de Bogotá - Colombia y durante eventos de altas y bajas precipitaciones. Se colectó un total de 96 taxones de los cuales el más abundante fue Simulium con 194 individuos (abundancia total). La densidad de deriva al igual que el aporte de biomasa de los macroinvertebrados acuáticos, fue mayor durante el período de bajas precipitaciones. Los dípteros (quironómidos) y los ácaros presentaron la mayor densidad de deriva mientras que los tricópteros (Triplectides) aportaron las mayores biomasas a la deriva. En la escala temporal de un día, no se presentaron diferencias en la densidad y la biomasa en la deriva entre el día y la noche.The variation of drift density of aquatic macroinvertebrates and biomass contribution of different immature and imagos stages were estimate on a stream segment of a first order tropical stream in Eastern hills of Bogotá - Colombia, during high and low rainfall periods. A total of 96 taxa were collected; Simulium was the most abundant with 194 individuals (total abundance). Drift density and biomass contributions, were greater during the dry period. Dipterans (chironomids) and mites showed the mayor drift density; trichopterans (Triplectides) showed the greater biomasses to the drift. Significant differences in diel drift pattern between the day and the night (K-S=1.86, p=0.002, n=185), but not in biomass contribution in drift, were observed.

JAVIER RODRÍGUEZ-BARRIOS; RODULFO OSPINA-TORRES; JUAN DAVID GUTIÉRREZ; HERNANDO OVALLE

2007-01-01

353

RELACIÓN ENTRE LA BIOMASA Y ALGUNAS CARACTERÍSTICAS MORFOLÓGICAS DE LAS BROMELIAS FITOTELMATAS DE UN BOSQUE ALTO ANDINO COLOMBIANO Relationships between biomass and morphological characters of phytotelmata bromeliads in a Colombian upper Andean forest  

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Full Text Available Se evaluaron algunas características morfológicas para seis especies de bromelias fitotelmata (Guzmania gloriosa, Racinaea tetrantha, Tillandsia biflora, T. complanata, T. fendleri y T. turneri) con el fin de establecer cuales características podrían utilizarse como estimadores indirectos de la biomasa total de la planta. El estudio se realizó en un bosque alto andino de la Sabana de Bogotá, Colombia, ubicado a 2900 m de altitud. Para cada especie se recolectaron entre 32 y 64 individuos en diferentes estadios de crecimiento, a cada uno de los cuales se le registró: 1) el número de hojas por roseta; 2) el perímetro de la base de la roseta; 3) la cobertura de la planta; 4) el largo de la lámina foliar; 5) la altura de la roseta; y 6) la biomasa total. Los resultados de la prueba Wilcoxon muestran que la cobertura fue la variable que más se relacionó con la biomasa. Una prueba de ajuste de curva mostró que la línea recta es la que más explica la relación entre la cobertura y la biomasa, permitiendo hacer estimaciones a partir de la ecuación sin ser necesario un muestreo destructivo.Some morphological characteristics were evaluated for six bromeliad phytotelmic species (Guzmania gloriosa, Racinaea tetrantha, Tillandsia biflora, T. complanata, T. fendleri and T. turneri) to establish which of those can be used as indirect estimators of total biomass. The present study was performed in a high Andean forest of the Savanna of Bogotá, Colombia, at 2900 m. We collected between 32 and 64 individuals per species in different developmental stages. For each one we registered 1) number of leaves, 2) the basal rosette perimeter, 3) coverage, 4), leaf length 5) the height of the rosette; and 6) total biomass. According to the results, coverage was the variable most related with biomass. A curve fitting analysis showed that a straight line best explained the relationship between coverage and biomass. Thus, the equation allows estimating biomass from coverage without the destructive sampling effect.

CAROLINA ISAZA; JULIO BETANCUR

2009-01-01

354

Bioadsorción de Cromo (VI) en Solución Acuosa por la Biomasa Celular de Cryptococcus neoformans y Helminthosporium sp/ Biosorption of Chromium (VI) from Aqueous Solutions by Fungal Biomass of Cryptococcus neoformans and Helminthosporium sp  

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Full Text Available Abstract in spanish Se determinó la bioadsorción de Cromo (VI) en solución por la biomasa celular de la levadura capsulada Cryptococcus neoformans y del hongo micelial Helminthosporium sp, por el método colorimétrico de la difenilcarbazida. La biomasa de C. neoformans fue más eficiente en la remoción de Cromo (VI) en solución (98%) que la de Helminthosporium sp (65%). La mayor bioadsorción para C. neoformans fue a pH=2.0 +/- 0.2, mientras que para Helminthosporium sp fue a pH=4.0 +/ (more) - 0.2, ambas a 28oC durante 24 horas con 0.2 mg/L de biomasa celular. Se concluye que las biomasas fúngicas remueven eficientemente Cromo (VI) en solución y pueden utilizarse para descontaminar nichos acuáticos contaminados con este metal. Abstract in english A determination was made on the biosorption of dissolved Chromium (VI) using cellular biomass of the encapsulated yeast Cryptococcus neoformans and the mycelial fungus Helminthosporium sp. using a diphenylcarbazide colorimetric method. The C. neoformans biomass was more efficient in removing Chromium (VI) from solution (98%) than the Helminthosporium sp. (65%). The highest biosorption for C. neoformans was at pH 2.0 + 0.02, while for Helminthosporium sp this occurred at p (more) H 4.0 + 0.2 , both at 28°C for 24 h employing 0.2 mg/L of cellular biomass. It is concluded that the fungal biomasses efficiently removed Chromium (VI) from solution and could be used for decontamination of aquatic habitats polluted with this metal.

Acosta, I.; Moctezuma-Zárate, M. G.; Gutiérrez, C.; Rodríguez, X.

2005-01-01

355

DENSIDAD Y BIOMASA DE MACROINVERTEBRADOS ACUÁTICOS DERIVANTES EN UNA QUEBRADA TROPICAL DE MONTAÑA (BOGOTÁ, COLOMBIA)/ Density and biomass of drifting aquatic macroinvertebrates in a tropical mountain creek at Bogotá, Colombia  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Se estimó la variación en la densidad de deriva de macroinvertebrados acuáticos y su aporte de materia orgánica en términos de biomasa de diferentes estados inmaduros e imagos, en un tramo de una quebrada tropical de montaña ubicada en los cerros orientales de Bogotá - Colombia y durante eventos de altas y bajas precipitaciones. Se colectó un total de 96 taxones de los cuales el más abundante fue Simulium con 194 individuos (abundancia total). La densidad de deri (more) va al igual que el aporte de biomasa de los macroinvertebrados acuáticos, fue mayor durante el período de bajas precipitaciones. Los dípteros (quironómidos) y los ácaros presentaron la mayor densidad de deriva mientras que los tricópteros (Triplectides) aportaron las mayores biomasas a la deriva. En la escala temporal de un día, no se presentaron diferencias en la densidad y la biomasa en la deriva entre el día y la noche. Abstract in english The variation of drift density of aquatic macroinvertebrates and biomass contribution of different immature and imagos stages were estimate on a stream segment of a first order tropical stream in Eastern hills of Bogotá - Colombia, during high and low rainfall periods. A total of 96 taxa were collected; Simulium was the most abundant with 194 individuals (total abundance). Drift density and biomass contributions, were greater during the dry period. Dipterans (chironomids (more) ) and mites showed the mayor drift density; trichopterans (Triplectides) showed the greater biomasses to the drift. Significant differences in diel drift pattern between the day and the night (K-S=1.86, p=0.002, n=185), but not in biomass contribution in drift, were observed.

RODRÍGUEZ-BARRIOS, JAVIER; OSPINA-TORRES, RODULFO; GUTIÉRREZ, JUAN DAVID; OVALLE, HERNANDO

2007-12-01

356

Nanomechanical actuation from phase transitions in individual VO2 micro-beams  

Science.gov (United States)

The mechanical response due to structural phase transitions in individual VO2 nanowires was quantitatively investigated in situ in a transmission electron microscope. The electron beam was employed to locally heat the nanowire, and stress-strain was measured in situ using a microfabricated push-to-pull device. Tensile loading was found to increase the metal-insulator transition temperature and decrease the insulator-insulator transition temperature, consistent with the phase diagram of VO2. These phase transitions resulted in an axial mechanical response of the VO2 nanowires, an effect that can potentially be used to actuate nanostructures or gauge the local temperature change induced by electron beam irradiation.

Guo, Hua; Wang, Kevin; Deng, Yu; Oh, Y.; Syed Asif, S. A.; Warren, O. L.; Shan, Z. W.; Wu, J.; Minor, A. M.

2013-06-01

357

Current induced Metal-Semiconductor Transition in VO2 grown on Pt  

Science.gov (United States)

Vanadium dioxide (VO2) exhibits a metal-semiconductor transition at 340K; this transition can also be triggered by an electric field or direct current injection. In this study VO2 was grown on 100 nm thick Pt bottom electrodes. The top Pt contacts were added for the transport measurements. The transport behavior indicated a reduced transition temperature. We have shown that the switching voltage for a Pt/VO2/Pt structure was as low as 0.3 V, and at this voltage we observed two orders of magnitude change in the resistance. XPS will be used to determine the valence state.

Lu, Jiwei; Kittiwatanakul, Salinporn; Wolf, Stuart

2013-03-01

358

Thin-film VO2 submillimeter-wave modulators and polarizers  

International Nuclear Information System (INIS)

Submillimeter-wave modulators and switchable polarizers have been fabricated from VO2 thin films deposited on sapphire substrates. By passing electric current pulses through elements made from these films, the films can be thermally cycled through the insulator-to-metal transition that occurs in VO2 at about 65 degreeC. In the insulating state, the films are found to have negligible effect on the transmission at submillimeter wavelengths, while above the phase transition the transmission is strongly reduced by the free-electron effects characteristic of a metal. Other possible applications of such switchable VO2 elements include variable bandpass filters and diffraction grating beam-steering devices

1977-07-01

359

Performance Analysis of Statistical Distributions for VoIP over WiMAX Access Networks  

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Full Text Available Statistical distributions are used to represent behavior of real VoIP traffic. This paper investigates the performance of VoIP traffic over WiMAX networks by examining statistical comparison of interarrival time distribution. The parameters are used to analyze the Quality of Service (QoS), like delay, jitter, throughput with respect to Voice Activity Detection (VAD) or Silence Detection (SD) in voice codec G.729. The simulation result indicates that the pareto distribution in interarrival time has a significant impact on the performance of VoIP in WiMAX network.

Gysberth Maurits Wattimena

2013-01-01

360

Thermochromism of metal-doped VO2 films deposited by dual-target sputtering  

Science.gov (United States)

Thermochromic VO2 films were prepared by reactive magnetron sputtering under various conditions of substrate temperature, total sputter pressure and oxygen flow ratio and characterized by XRD, RBS, AFM and spectrophotometry. Films with VO2 single phase were formed from a fairly low substrate temperature of 300 degree(s)C by precisely controlling the oxygen flow ratio. The use of vanadium-nucleated substrates significantly improved the crystallinity of VO2. Tungsten doped V1-xWxO2 films with x equals 0 approximately 0.26 were formed by dual-target sputtering and the thermochromism of films was evaluated. The tungsten doping linearly hysteresis loop width.

Jin, Ping; Tazawa, Masato; Yoshimura, Kazuki; Miki, Takeshi; Igarashi, K.; Tanemura, Sakae

1994-09-01