279,942 research outputs found
End-Expiratory and Tidal Volumes Measured in Conscious Mice Using Single Projection X-Ray Images
No full textThe evaluation of airway resistance (Raw) in conscious mice requires both end-expiratory (V-e) and tidal volumes (V-t) ( Lai-Fook SJ and Lai YL. J Appl Physiol 98: 2204-2218, 2005) . In anesthetized BALB/c mice we measured lung area (A(L)) from ventral-to-dorsal x-ray images taken at FRC (V-e) and after air inflation with 0.25 and 0.50 ml (Delta V-L). Total lung volume (V-L) described by equation: V-L = Delta V-L + V-FRC = KA(L)(1 .5) assumed uniform (isotropic) inflation. Total V-FRC averaged 0.55 ml, consisting of 0.10 ml tissue, 0.21 ml blood and 0.24 ml air. K averaged 1. 84. In conscious mice in a sealed box, we measured the peak-to-peak box pressure excursions (Delta P-b) and x-rays during several cycles. K was used to convert measured A(L)(1.5) to V-L values. We calculated V-e and V- t from the plot of V-L vs. cos(alpha-phi). Phase angle alpha was the minimum point of the P-b cycle to the x-ray exposure. Phase difference between the P-b and V-L cycles (phi) was measured from Delta P-b values using both room- and body-temperature humidified box air. A similar analysis was used after aerosol exposures to bronchoconstrictor methacholine (Mch), except that phi depended also on increased Raw. In conscious mice, V-e (0.24 ml) doubled after Mch (50-125 mg/ml) aerosol exposure with constant V-t, frequency (f), Delta P-b, and Raw. In anesthetized mice, in addition to an increased V-e, repeated 100 mg/ml Mch exposures increased both Delta P-b and Raw and decreased f to apnea in 10 min. Thus conscious mice adapted to Mch by limiting Raw, while anesthesia resulted in airway closure followed by diaphragm fatigue and failure
The theory and practice of utopia in our troubled times : a conversation with author Larissa Lai and critic Sherryl Vint
No full textAmid current global crises, the international conference “The Knock at the Door: Utopian Dreams for Post-Covid Times,” jointly organized by the University of Huelva (Spain) and the University of Calgary (Canada) on May 21–24, 2023, at the University of Huelva, provided a forum for reflecting upon the role played by speculative fiction in (re)imagining better futures, while remaining vigilant to possible threats and dangers. The title of the conference, borrowed from philosopher John Rajchman,1 is intentionally ambiguous. Lying behind that door could be total liberation for all—or it could be secret police who lead us toward genocides, deportation, rapes, and mass graves. Taking this dichotomous trope, “the knock at the door,” as a point of departure, professors Larissa Lai (University of Toronto, Canada; recipient of a Maria Zambrano fellowship at the University of Huelva at the time of the interview) and Sherryl Vint (University of California Riverside, USA) engaged...Depto. de Estudios Ingleses: Lingüística y LiteraturaFac. de Ciencias Económicas y EmpresarialesTRUEpu
Does Economic Optimisation Explain LAI and Leaf Trait Distributions Across an Amazon Soil Moisture Gradient?
No full textModel outputs presented in Flack-Prain, S., Meir, P., Malhi, Y., Smallman, T. L., & Williams, M. (2020).Does Economic Optimisation Explain LAI and Leaf Trait Distributions Across an Amazon Soil Moisture Gradient?. Global Change Biology
Lenguaje y estructura en comunidades polarizadas
Get PDFPhD thesis in Computer Science has been written by Mirko Lai under the supervision of Prof. Paolo Rosso (Universitat Politècnica de València), Dr. Giancarlo Ruffo (University of Turin) and Dr. Viviana Patti (University of Turin). This thesis was developed under a cotutelle between the Universitat Politècnica de València, Spain and the University of Turin, Italy. The thesis defense was done in Turin, Italy on February 11, 2019. The doctoral committee was integrated by: Leo Ferres (Universidad del Desarrollo, Chile), Delfina Malandrina (Università degli Studi di Salerno, Italy) and Sara Tonelli (Fondazione Bruno Kessler, Italy).Tesis doctoral en Informática ha sido realizada por Mirko Lai y dirigida por el Prof. Paolo Rosso (Universitat Politècnica de València), Dr. Giancarlo Ruffo (University of Turin) y la Dra. Viviana Patti (University of Turin) en el marco de un convenio de cotutela entre la Universitat Politècnica de València, España y la Universidad de Turin, Italia. La defensa de la tesis fue en Turin, Italia el 11 de febrero de 2019 ante un tribunal compuesto por: Leo Ferres (Universidad del Desarrollo, Chile), Delfina Malandrina (Università degli Studi di Salerno, Italia) y Sara Tonelli (Fondazione Bruno Kessler, Italia)
Optical instruments for measuring leaf area index in low vegetation : application in Arctic ecosystems
Get PDFAuthor Posting. © Ecological Society of America, 2005. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 15 (2005): 1462–1470, doi:10.1890/03-5354.Leaf area index (LAI) is a powerful diagnostic of plant productivity. Despite the fact that many methods have been developed to quantify LAI, both directly and indirectly, leaf area index remains difficult to quantify accurately, owing to large spatial and temporal variability. The gap-fraction technique is widely used to estimate the LAI indirectly. However, for low-stature vegetation, the gap-fraction sensor either cannot get totally underneath the plant canopy, thereby missing part of the leaf area present, or is too close to the individual leaves of the canopy, which leads to a large distortion of the LAI estimate. We set out to develop a methodology for easy and accurate nondestructive assessment of the variability of LAI in low-stature vegetation. We developed and tested the methodology in an arctic landscape close to Abisko, Sweden.
The LAI of arctic vegetation could be estimated accurately and rapidly by combining field measurements of canopy reflectance (NDVI) and light penetration through the canopy (gap-fraction analysis using a LI-COR LAI-2000). By combining the two methodologies, the limitations of each could be circumvented, and a significantly increased accuracy of the LAI estimates was obtained. The combination of an NDVI sensor for sparser vegetation and a LAI-2000 for denser vegetation could explain 81% of the variance of LAI measured by destructive harvest. We used the method to quantify the spatial variability and the associated uncertainty of leaf area index in a small catchment area.This research was funded by U.S. National Science Foundation
grant DEB0087046
Leaf area index estimation in a pine plantation with LAI-2000 under direct sunlight conditions: relationship with inventory and hydrologic variables
Get PDF[EN] LAI is a key factor in light and rainfall interception processes in forest stands and, for this reason, is called to play
an important role in global change adaptive silviculture. Therefore, it is necessary to develop practical and operative
methodologies to measure this parameter as well as simple relationships with other silvicultural variables. This work
has studied 1) the feasibility of LAI-2000 sensor in estimating LAI-stand when readings are taken under direct sunlight
conditions; and 2) the ability of LAI in studying rainfall partitioned into throughfall (T) in an Aleppo pine stand
after different thinning intensities, as well as its relationships to basal area, (G), cover (FCC), and tree density (D).
Results showed that the angular correction scheme applied to LAI-2000 direct-sunlight readings stabilized them for
different solar angles, allowing a better operational use of LAI-2000 in Mediterranean areas, where uniform overcast
conditions are difficult to meet and predict. Forest cover showed the highest predictive ability of LAI (R2 = 0.98;
S = 0.28), then G (R2 = 0.96; S = 0.43) and D (R2 = 0.50; S = 0.28). In the hydrological plane, T increased with thinning
intensity, being G the most explanatory variable (R2 = 0.81; S = 3.07) and LAI the one that showed the poorest relation
with it (R2 = 0.69; S = 3.95). These results open a way for forest hydrologic modeling taking LAI as an input variable
either estimated form LAI-2000 or deducted from inventory data[ES] El índice de área foliar (LAI) es una variable clave en los procesos de intercepción de la lluvia y la luz en masas forestales
y por tanto tiene gran potencial en la práctica de la selvicultura adaptativa al cambio climático, de ahí la necesidad
de establecer tanto metodologías sencillas para su estimación, como su relación con las principales variables
de gestión forestal. Este trabajo tiene un doble objetivo: 1) determinar la viabilidad del sensor LAI-2000 para estimar
el LAI en condiciones de radiación directa aplicando una corrección angular y 2) conocer la utilidad del LAI en el estudio
de trascolación de la lluvia (T) en una masa de pino carrasco con distintas intensidades de clara así como sus
relaciones con el área basimétrica (G), la densidad de arbolado (D) y la fracción de cabida cubierta (FCC). Los resultados
indican que la corrección angular estabiliza los valores LAI-2000 tomados bajo radiación solar directa, permitiendo
una mayor operatividad del sensor en condiciones mediterráneas, donde la nubosidad uniforme resulta poco
frecuente e imprevisible. La variable FCC fue la que presentó un mayor poder predictivo del LAI (R2 = 0,98; S = 0,28),
seguida de G (R2 = 0,96; S = 0,43) y D (R2 = 0,50; S = 0,28). En el aspecto hidrológico, la trascolación aumentó con la
intensidad de clara, siendo G la variable más correlacionada (R2 = 0,81; S = 3,07) y LAI la que menos (R2 = 0,69;
S = 3,95). Los resultados evidencian la versatilidad de trabajar con LAI estimado de forma sencilla o bien a partir de
inventarios disponibles, para su uso en modelos de mayor ámbito espacial.Molina, A.; Campo García, ADD. (2011). Estimación del Índice de área foliar en pinares de repoblación con LAI-2000 bajo radiación solar directa: relación con variables de inventario e hidrológicas. Investigación Agraria Sistemas y Recursos Forestales. 20(1):108-121. doi:10.5424/fs/2011201-10009S108121201Aboal, J. ., Jiménez, M. ., Morales, D., & Gil, P. (2000). Effects of thinning on throughfall in Canary Islands pine forest — the role of fog. Journal of Hydrology, 238(3-4), 218-230. doi:10.1016/s0022-1694(00)00329-2Asner, G. P., Scurlock, J. M. O., & A. Hicke, J. (2003). Global synthesis of leaf area index observations: implications for ecological and remote sensing studies. Global Ecology and Biogeography, 12(3), 191-205. doi:10.1046/j.1466-822x.2003.00026.xCescatti, A. (1998). Effects of needle clumping in shoots and crowns on the radiative regime of a Norway spruce canopy. Annales des Sciences Forestières, 55(1-2), 89-102. doi:10.1051/forest:19980106CHEN, J. M., & BLACK, T. A. (1992). Defining leaf area index for non-flat leaves. Plant, Cell and Environment, 15(4), 421-429. doi:10.1111/j.1365-3040.1992.tb00992.xChen, J. M., & Cihlar, J. (1996). Retrieving leaf area index of boreal conifer forests using Landsat TM images. Remote Sensing of Environment, 55(2), 153-162. doi:10.1016/0034-4257(95)00195-6Crockford, R. H., & Richardson, D. P. (2000). Partitioning of rainfall into throughfall, stemflow and interception: effect of forest type, ground cover and climate. Hydrological Processes, 14(16-17), 2903-2920. doi:10.1002/1099-1085(200011/12)14:16/173.0.co;2-6Deblonde, G., Penner, M., & Royer, A. (1994). Measuring Leaf Area Index with the Li-Cor LAI-2000 in Pine Stands. Ecology, 75(5), 1507-1511. doi:10.2307/1937474Grier, C. G., & Running, S. W. (1977). Leaf Area of Mature Northwestern Coniferous Forests: Relation to Site Water Balance. Ecology, 58(4), 893-899. doi:10.2307/1936225Keenan, T., García, R., Friend, A. D., Zaehle, S., Gracia, C., & Sabate, S. (2009). Improved understanding of drought controls on seasonal variation in Mediterranean forest canopy CO2 and water fluxes through combined in situ measurements and ecosystem modelling. Biogeosciences Discussions, 6(1), 2285-2329. doi:10.5194/bgd-6-2285-2009Leblanc, S. G., & Chen, J. M. (2001). A practical scheme for correcting multiple scattering effects on optical LAI measurements. Agricultural and Forest Meteorology, 110(2), 125-139. doi:10.1016/s0168-1923(01)00284-2Llorens, P., Poch, R., Latron, J., & Gallart, F. (1997). Rainfall interception by a Pinus sylvestris forest patch overgrown in a Mediterranean mountainous abandoned area I. Monitoring design and results down to the event scale. Journal of Hydrology, 199(3-4), 331-345. doi:10.1016/s0022-1694(96)03334-3Llorens, P., & Domingo, F. (2007). Rainfall partitioning by vegetation under Mediterranean conditions. A review of studies in Europe. Journal of Hydrology, 335(1-2), 37-54. doi:10.1016/j.jhydrol.2006.10.032López-Serrano, F. R., Landete-Castillejos, T., Martı́nez-Millán, J., & Cerro-Barja, A. del. (2000). LAI estimation of natural pine forest using a non-standard sampling technique. Agricultural and Forest Meteorology, 101(2-3), 95-111. doi:10.1016/s0168-1923(99)00171-9McDowell, N. G., Adams, H. D., Bailey, J. D., & Kolb, T. E. (2007). The role of stand density on growth efficiency, leaf area index, and resin flow in southwestern ponderosa pine forests. Canadian Journal of Forest Research, 37(2), 343-355. doi:10.1139/x06-233Navarro Cerrillo, R. M., Sanchez de la Orden, M., Gomez Bonilla, J., Garcia-Ferrer, A., Hernandez Clemente, R., & Lanjeri, S. (2010). LIDAR-based estimation of leaf area index on Holm oak [Quercus ilex L. subsp. ballota (Desf.) Samp.] trees. Forest Systems, 19(1), 61. doi:10.5424/fs/2010191-01167Olthof, I., King, D. J., & Lautenschlager, R. A. (2003). Overstory and understory leaf area index as indicators of forest response to ice storm damage. Ecological Indicators, 3(1), 49-64. doi:10.1016/s1470-160x(03)00010-4Snee, R. D. (1977). Validation of Regression Models: Methods and Examples. Technometrics, 19(4), 415. doi:10.2307/1267881Stenberg, P. (1996). Correcting LAI-2000 estimates for the clumping of needles in shoots of conifers. Agricultural and Forest Meteorology, 79(1-2), 1-8. doi:10.1016/0168-1923(95)02274-0Stenberg, P., Linder, S., Smolander, H., & Flower-Ellis, J. (1994). Performance of the LAI-2000 plant canopy analyzer in estimating leaf area index of some Scots pine stands. Tree Physiology, 14(7-8-9), 981-995. doi:10.1093/treephys/14.7-8-9.98
Measurement of bar{B0} Meson Properties Via Partial Reconstruction of the Decay bar{B0} -> D*+ l- ar{nu}
No full textUsing data recorded by the CLEO II detector operating at the Upsilon(4S) resonance at the Cornell Electron Storage Ring, several properties of B mesons are measured using a partially reconstructed tag of the decay mode bar{B0} -> D*+ l- bar{nu}. Using 2.38 fb**{-1} of on-resonance data and the averaged B meson semileptonic branching fraction through inclusive lepton momentum spectrum obtained by previous CLEO analysis, we measure the B0 and B- semileptonic branching fraction to be (10.78 +/- 0.60 +/- 0.69)% and (10.25 +/- 0.57 +/- 0.65)% respectively, which yields the lifetime ratio tau_+/tau_0 = 0.950 +0.117-0.080 +0.091-0.068, assuming the equality of semileptonic partial branching width for bar{B0} and B-. With a larger dataset of 3.1 fb**{-1}, we measured the B0-bar{B0} mixing parameter chi_d to be 0.189 +/- 0.019 +/- 0.006.Ph. D
Pseudorandomness analysis of the (extended) Lai–Massey scheme
Get PDFIn this paper we find that the two-round (extended) Lai–Massey scheme is not pseudorandom and three-round (extended) Lai–Massey scheme is not strong pseudorandom. Combined with previous work, we prove that three rounds are necessary and sufficient for the pseudorandomness and four rounds are necessary and sufficient for the strong pseudorandomness
Estimation of leaf area index from PROBA/CHRIS hyperspectral multi-angular data
No full textLeaf Area Index (LAI) is a key structural and functional biophysical variable of the vegetated surfaces which is important in quantifying evapotranspiration rates and the energy exchange of terrestrial vegetation. Remote sensing offers a method of providing estimates of LAI through the analysis of the Bidirectional Reflectance Distribution Function (BRDF), an angular-dependent surface response. High-resolution, multi-angular and hyperspectral image data from PROBA/CHRIS (Project On-Board Autonomy/ Compact High Resolution Imaging Spectrometer) are used to estimate LAI. The retrieval of LAI is accomplished using the 1D turbid-medium canopy reflectance model, SAIL, coupled with the leaf reflectance model, PROSPECT REDUX. Look-up-tables are generated using scene-specific parameters required to invert the physically based model. Two experiments are performed to examine the contribution of multispectral versus hyperspectral reflectances (nadir direction) and single-look versus multi-look hyperspectral reflectances in deriving the LAI. Image data of the calibration/validation site at Chilbolton, Hampshire, UK are used for the inversion. In addition, ground measurements of LAI are compared with the retrieved LAI estimates. Retrieved LAI estimates using various spectral and directional sampling suggest that the spectro-directional reflectances from CHRIS provides more accurate results than their lower-resolution counterparts such as single-look and multispectral reflectances
Effect of Indium Fluctuation on the Photovoltaic Characteristics of InGaN/GaN Multiple Quantum Well Solar Cells
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