941 research outputs found
GDP, share prices and share returns: Australian and New Zealand evidence
With the aim of predicting share market returns, many empirical studies have delved into how financial and macroeconomic variables can be used to forecast return variability. The aim of this paper is to examine whether the ratio of aggregate share price to GDP can capture the variation of future returns on the aggregate share market within Australia and New Zealand. Using quarterly and semi-annual data for the period 1991-2003 for New Zealand and 1982-2006 for Australia, this study finds that the ratio of share price to GDP indeed captures a significant amount of the variation of returns on the New Zealand share market as well as the Australian share market; however results for Australian data do vary, depending on the sample period. Results in this paper generally provide support for the theory behind previous papers, specifically that of Rangvid (2006)
Verificación de un equipo FDR para la medida del contenido de agua del suelo en dos sistemas de cultivo
[ES] Se ha estudiado el comportamiento de un equipo FDR (sonda multisensor EnviroSCAN, Sentek PTY LTD, Adelaine, South Autralia) para su uso en la programación de riegos de dos sistemas de explotación diferentes (plantación de olivar regada por goteo y parcela de trigo regada por aspersión). En cada una de ellas se instaló un equipo EnviroSCAN con varias sondas de medida del contenido de agua en profundidad, y varios tubos de acceso de sonda de neutrones. En primer lugar, se compararon los contenidos de agua calculados a partir de las medidas realizadas con ambos sistemas de medida. Se encontraron buenos ajustes lineales (R2 mayores de 0.70), salvo para los sensores más profundos, es decir, con pequeñas variaciones de humedad (valores entre 0.043 a 0.054 cm3/cm3), y en las parcelas no regadas. Además, era apreciable la descalibración del sistema de medida EnviroSCAN, consecuencia de la utilización de la recta de calibración facilitada por el fabricante. Por último, se calibró el sistema EnviroSCAN utilizando los datos del primer año de medida para corregir los del segundo. Así, se encontró que aunque no se mejoraron las regresiones realizadas, el RMSE se mejoró considerablemente tanto para las medidas superficiales, como para los contenidos de humedad medios del perfil de profundidad determinada.Moreno-Pérez, M.; Villalobos Martín, F.; Fereres Castiel, E. (2005). Verificación de un equipo FDR para la medida del contenido de agua del suelo en dos sistemas de cultivo. Ingeniería del agua. 12(4):345-359. https://doi.org/10.4995/ia.2005.2570OJS345359124Baumhardt, R.L; Lascano, R.J.; Evett, S.R. (2000). Soil material, temperature, and salinity effects on calibration of multisensor capacitance probes. Soil Sci. Soc. Am. J. Nov/Dec 2000. v. 64 (6) p. 1940-1946.Bell, J.P.; Dean, T.J.; Hodnett, M.G. (1987). Soil moisture measurement by an improved capacitance technique. II: field techniques, evaluation and calibration, J. Hydrol., 93, 79-90.Berengena, J. y Roldán J. (1979). Water needs of soybeans in Guadalquivir Valley. Serie producción vegetal. Instituto Nacional de Investigaciones Agrarias.1979. (10) p. 101-119.Campbell, G.S. y Mulla, D.J. (1990). Measurement of soil water content and potential. P. 127-142. In: Irrigation of Agricultural Crops. (B.A. Stewart y D.R. Nielsen, eds.) Amer. Soc. Agric. Engn., Madison, WisCampbell G.S. y Campbell, M.D. (1982). Irrigation scheduling using soil moisture measurements: theory and practice. Adv. Irrig., vol. 1, pp. 25-42Dobson, M.C.; Ulaby, F.T.; Hallikainen, M.T.; El-Rayes, M.A. (1985). Microwave dielectric behavior or wet soil Part II: Dielectric mixing models. IEEE Trans. Geosci. Remote Sens. 23:35-46.Evett, R.S. y Steiner, J.L. (1995). Precision of neutron scattering and capacitance type soil water content gauges from field calibration. Soil Sci. Soc. Am. J. 59: 961-968.Fares A. y Alva, A.K. (2000). Soil water components based on capacitance probes in a sandy soil. Soil Sci. Soc. Am. J., 64: 311-318Fernández Fernández Mª D., Bonachela Castaño S., Contreras Sánchez A. y González Céspedes A. Mª. (2004) Evaluación de un equipo de medida continua de humedad basado en la reflectometría en el dominio de frecuencias en un suelo enarenado. XXII Congreso Nacional de Riegos. Logroño.Dean, T.J.; Bell, J.P.; Baty, A.J.B. (1987). Soil moisture measurement by all improved capacitance technique. Part I. Sensor design and performance. J. Hydrol. (Amsterdam) 93:67-78.Gardner, C.M.K., Bell, J.P.; Cooper, J.D.; Dean, T.J.; Hodnett, M.G.; Gardner, N. (1991). Soil water content. p. 1-73. In R.A. Smith and C.E. Mullings (ed.) Soil analysis -Physical methods. Marcel Dekker. New York.Girona, J.; Mata, M.; Fereres, E.; Goldhamer, D.A.; Cohen, M. (2002). Evapotranspiration and soil water dynamics of peach trees under water deficits. Agr. Water Manage. 54: 107-122.Goldhamer, D.A.; Fereres, E.; Mata, M.; Girona, J.; Cohen, M. (1999). Sensitivity of continuous and discrete plant and soil water status monitoring in peach trees subjected to deficit irrigation. J. Am. Soc. Hort. Sci. 124 (4), 437-444.Green, R.E. y Topp, G.C. (1992). Survey of use of field methods for measuring soil hydraulic properties. In: Topp, G.C., et al. (Eds.), Advanced in Measurement of Soil Physical Properties: Bringing Theory into Practice. Soil Sci. Soc. Am. Special Publ. no.30, Madison, WI. pp. 281-288.Hanson, B.R. y Peters, D. (2000). Soil type affects accuracy of dielectric moisture sensors. Calif. Agric.: 55 (3): 43-47.Kuraz, V. (1982). Testing of a field dielectric soil moisture meter. ASTM Geotech. Test. J. 4:111-116.Kutilek, M. y Nielsen, D.R. (1994). Soil hydrology. Catena, Cremlingen-Destedt, p 370Ministerio de Agricultura, Pesca y Alimentación (2002). Hechos y cifras del sector agroalimentario y del medio rural español. Secretaría técnica, Madrid.Mead, R.M.; Ayars, J.E.; Liu, J. (1995). Evaluating the influence of soil texture, bulk density and soil water salinity on a capacitance probe calibration. ASAE Pap. 95-3264. ASAE. St. Joseph. MI.Mead, R.M.; Soppe, R.W.O.; Ayars, J.E. (1996). Capacitance probe observations of daily soil moisture fluctuations: p. 916-923. In C.R. Camp et al. (ed.) Evapotranspiration and irrigation scheduling. Proc. Int. Conf. San Antonio. TX. 3-6 Nov 1996. ASAE. St. Joseph. MI.Morgan, K.T.; Parsons, L.R.; Wheaton, T.A.; Pitts, D.J.; Obreza, T.A. (1999). Field Calibration of a Capacitance Water Content Probe in Fine Sand Soils. Soil Sci. Soc. Am. J. 63: 987-989.Ould Mohamed, S.; Bertuzzi, P.; Bruend, A.; Raison, L.; Bruckler, L. (1997). Field evaluation and error analysis of soil water content measurement using the capacitance probe method. Soil Sci. Soc. Am. J. 61: 399-408.Paltineanu, I.C. y Starr, J.L. (1997). Real-time soil water dynamics using multisensor capacitance probes: Laboratory Calibration. Soil Sci. Soc. Am. J. 61: 1576-1585.Richards, L.A. (1949). Soil moisture tensiometer materials and construction. Soil Sci. 53:241-248.Roth, K.; Schulin, R.; Flühler, H.; Attinger, W. (1990). Calibration of time domain ref1ectometry for water content measurement using a composite dielectric approach. Water Resour. Res. 26:2267-2273.Starr, L. y Paltineanu, I.C. (1998). Real-time soil water dynamics over large areas using multisensor capacitance probes and monitoring system. Soil & Tillage Research 47: 43-49.Thomas, A.M. (1966). In situ measurement of moisture in soil and similar substances by 'fringe' capacitance. J. Sci. Instrum. 43:21-27.Tomer, M.D., y Anderson, J.L. (1995). Field evaluation of a soil water-capacitance probe in a fine sand. Soil Sci. 159:90-97.Veldkamp E. y O'Brien, J. (2000). Calibration of a Frequency Domain Reflectometry Sensor for Humid Tropical Soils of Volcanic Origin. Soil Sci. Soc. Am. J. 64:l549-l553.Villalobos, F. (1988). Los procesos de evaporación, transpiración y precipitación en los modelos de programación de riegos. Tesis doctoral. Universidad de Córdoba.Villalobos, F.J. (1993). Los servicios de asesoramiento de riegos y las necesidades hídricas de los cultivos. Riegos y Drenajes XXI, 71: 24-28.Wobschall, D. (1978). A frequency shift dielectric soil moisture sensor. IEEE Trans. Geosci. Electron. GE-16(2):112-118.Zekri, M. y Parsons, L.R. (1999). Determination of field capacity in a Florida sandy soil and drainage time at different depths. Hort Technology. Apr/June 1999. v. 9 (2) p. 258-261
Is the Soil Frozen, or Not? An Algorithm Using Weather Records
Frozen soil water is important in hydrologic events because it reduces water infiltration. The presence
of soil ice can be predicted reasonably well from detailed knowledge of the soil and microclimatic
variables, but this type of information is generally unavailable. Consequently, the purpose of this study
was to start with fundamental relations and see how well frozen soil conditions could be identified from
daily weather station records of maximum-minimum temperatures, solar radiation, and snowfall. Two
relations were developed, one based on the soil-atmosphere energy budget and the other on the heat flux
across the soil surface layer. Conceptually, the two equations may be used together to give daily snowmelt
as well as soil thawing and freezing rates, but in practice, the snowmen prediction is probably not yet
accurate enough for most practical applications. The simpler equation, describing the heat flux in the soil
surface, does not require solar radiation input, yet it gave fair predictions of frozen soil on five diverse
sites studied in the Palouse region of eastern Washington. Both approaches require only a single constant
that accounts for individual site conditions such as slope, aspect, cover, and soil properties
Water and Salt Movement in Unsaturated Frozen Soil: Principles and Field Observations
Soil temperatures, electrical conductivities, and water redistribution were measured at four field sites during a 30-day period in which the soil was never completely thawed. The soil on each site was a silt loam with varying aspects and vegetation covers. Both upward and downward flow of water and solutes were observed. Assuming that liquid water flow in frozen soil is analogous to unsaturated liquid flow in unfrozen soil, led to a simple equation that in general agreed with the field observations. The equation requires knowledge of the soil temperatures, the solute concentrations, and two constants that characterize the soil's water release curve and saturated hydraulic conductivity.
Infiltration and frost heaving are discussed with respect to this simple theory. Water in frozen soil flows from high to low temperatures and from high to low salt concentrations. Consequently, solutes in even very low salt soils are important in decreasing frost heave and increasing infiltration. The liquid flow is so closely coupled with temperature that heat flow must be considered simultaneously in any comprehensive analysis. This coupling, as expressed in the simple liquid flow equation, accounts for the effect of soil water content on frost heave rates and the effects of temperature on maximum heaving pressures
Tiered Human Integrated Sequence Search Databases for Shotgun Proteomics.
The results of analysis of shotgun proteomics mass spectrometry data can be greatly affected by the selection of the reference protein sequence database against which the spectra are matched. For many species there are multiple sources from which somewhat different sequence sets can be obtained. This can lead to confusion about which database is best in which circumstances-a problem especially acute in human sample analysis. All sequence databases are genome-based, with sequences for the predicted gene and their protein translation products compiled. Our goal is to create a set of primary sequence databases that comprise the union of sequences from many of the different available sources and make the result easily available to the community. We have compiled a set of four sequence databases of varying sizes, from a small database consisting of only the ∼20,000 primary isoforms plus contaminants to a very large database that includes almost all nonredundant protein sequences from several sources. This set of tiered, increasingly complete human protein sequence databases suitable for mass spectrometry proteomics sequence database searching is called the Tiered Human Integrated Search Proteome set. In order to evaluate the utility of these databases, we have analyzed two different data sets, one from the HeLa cell line and the other from normal human liver tissue, with each of the four tiers of database complexity. The result is that approximately 0.8%, 1.1%, and 1.5% additional peptides can be identified for Tiers 2, 3, and 4, respectively, as compared with the Tier 1 database, at substantially increasing computational cost. This increase in computational cost may be worth bearing if the identification of sequence variants or the discovery of sequences that are not present in the reviewed knowledge base entries is an important goal of the study. We find that it is useful to search a data set against a simpler database, and then check the uniqueness of the discovered peptides against a more complex database. We have set up an automated system that downloads all the source databases on the first of each month and automatically generates a new set of search databases and makes them available for download at http://www.peptideatlas.org/thisp/
Rigorous results on superconducting ground states for attractive extended Hubbard models
We show that the exact ground state for a class of extended Hubbard models
including bond-charge, exchange, and pair-hopping terms, is the Yang
"eta-paired" state for any non-vanishing value of the pair-hopping amplitude,
at least when the on-site Coulomb interaction is attractive enough and the
remaining physical parameters satisfy a single constraint. The ground state is
thus rigorously superconducting. Our result holds on a bipartite lattice in any
dimension, at any band filling, and for arbitrary electron hopping.Comment: 12 page
Water conservation under reduced tillage systems
Water is important for dryland crop production. Seldom is rainfall
sufficient or adequately distributed during a growing season so that dryland
crops can produce to their fullest potential. It is necessary to have
stored water available in the soil to supplement inadequate growing season
rainfall for economical crop production. Stored water is especially
important in the Inland Pacific Northwest of north central Oregon,
southeastern Washington, and northern Idaho, where 65% of annual
precipitation occurs during the six-month (Sept. 1 to Feb. 28) winter period
and 30% during the four-month (March 1 to June 30) growing season. Stored
water is also important in the Eastern Idaho Plateau where the low annual
precipitation is nearly evenly distributed over the months of the year.
The water balance equation tells us that change in water content in the
soil - precipitation + inflow - runoff + upward flow - drainage -
evapotranspiration (ET). Any cultural practice that decreases runoff or ET
can result in increased water in the soil. To store adequate quantities
of water, deep soils (> 60 inches) with good infiltration and water holding
capacity are required. Summer fallow has long been the traditional practice
for storing water in soils for later use by crops. Fallow periods vary from
14 to 15 months where winter small grains are seeded to 21 months where
spring small grains are seeded. Water storage efficiency for fallow is low,
ranging from 10 to 35% in the Great Plains and the Southwest; to 30-37% in
eastern Idaho and northern Utah; to 40-45% of precipitation in the Inland
Pacific Northwest (Evans and Lemon, 1957). Good water conservation yields
increased crop production, stability of production, and increased water use
efficiency. Soil tillage and residue management play significant roles in
collection and storage of precipitation in the soil.
Our objectives are to discuss insights in water conservation gained under
the STEEP (Solutions to Economic and Environmental Problems) program
(Oldenstadt et al., 1982) during these last ten years and problems that
remain. New research information will be discussed under topics of crop
residues, conservation tillage systems, fallow and models
The role of Hall diffusion in the magnetically threaded thin accretion discs
We study role of the Hall diffusion in the magnetic star-disc interaction. In
a simplified steady state configuration, the total torque is calculated in
terms of the fastness parameter and a new term because of the Hall diffusion.
We show the total torque reduces as the Hall term becomes more significant.
Also, the critical fastness parameter (at which the total torque is zero)
reduces because of the Hall diffusion.Comment: Accepted for publication in Astrophysics and Space Scienc
CHecklist for statistical Assessment of Medical Papers: the CHAMP statement
Misuse of statistics in medical and sports science research is common and may lead to detrimental consequences to healthcare. Many authors, editors and peer reviewers of medical papers will not have expert knowledge of statistics or may be unconvinced about the importance of applying correct statistics in medical research. Although there are guidelines on reporting statistics in medical papers, a checklist on the more general and commonly seen aspects of statistics to assess when peer-reviewing an article is needed. In this article, we propose a CHecklist for statistical Assessment of Medical Papers (CHAMP) comprising 30 items related to the design and conduct, data analysis, reporting and presentation, and interpretation of a research paper. While CHAMP is primarily aimed at editors and peer reviewers during the statistical assessment of a medical paper, we believe it will serve as a useful reference to improve authors’ and readers’ practice in their use of statistics in medical research. We strongly encourage editors and peer reviewers to consult CHAMP when assessing manuscripts for potential publication. Authors also may apply CHAMP to ensure the validity of their statistical approach and reporting of medical research, and readers may consider using CHAMP to enhance their statistical assessment of a paper
A CHecklist for statistical Assessment of Medical Papers (the CHAMP statement): explanation and elaboration
Misuse of statistics in medical and sports science research is common and may lead to detrimental consequences to healthcare. Many authors, editors and peer reviewers of medical papers will not have expert knowledge of statistics or may be unconvinced about the importance of applying correct statistics in medical research. Although there are guidelines on reporting statistics in medical papers, a checklist on the more general and commonly seen aspects of statistics to assess when peer-reviewing an article is needed. In this article, we propose a CHecklist for statistical Assessment of Medical Papers (CHAMP) comprising 30 items related to the design and conduct, data analysis, reporting and presentation, and interpretation of a research paper. While CHAMP is primarily aimed at editors and peer reviewers during the statistical assessment of a medical paper, we believe it will serve as a useful reference to improve authors’ and readers’ practice in their use of statistics in medical research. We strongly encourage editors and peer reviewers to consult CHAMP when assessing manuscripts for potential publication. Authors also may apply CHAMP to ensure the validity of their statistical approach and reporting of medical research, and readers may consider using CHAMP to enhance their statistical assessment of a paper
- …