نتایج جستجو برای: climatic data

تعداد نتایج: 2432386  

Journal: :Respiratory care 2014
Ignasi Garcia-Olivé Jose A Fiz Jose Sanz-Santos Carlos Martínez-Rivera Marisol Prats Juan Ruiz-Manzano

BACKGROUND Although some authors have suggested that there is some seasonal periodicity of hemoptysis, or relation to respiratory tract infections, the association of influenza or climatic parameters with hemoptysis has been poorly investigated. Our aim was to describe the relationship between influenza and climatic parameters with severe hemoptysis that required bronchial artery embolization (...

2002
Michael H. Graham Paul K. Dayton Jon M. Erlandson

Organisms face continual fluctuations in global climatic processes to which they must adapt or perish. Considering that many species are key habitat formers and energy producers, such responses to climate change can have significant population, community and even ecosystem consequences. Paleo-records of ecosystem responses to past environmental variability have proven invaluable for studying im...

2000
Ronald I. Dorn

For the last two decades, climatically based interpretations have been the major focus in evolutionary studies of dryland alluvial fans. Climatic hypotheses to explain the development of alluvial fans in southern Death Valley, however, do not fare well when they are assessed with criteria used by philosophers of science. First and foremost, dating techniques do not have the chronometric precisi...

Journal: :Proceedings. Biological sciences 2014
Maria Fernanda Bonetti John J Wiens

The evolution of climatic niche specialization has important implications for many topics in ecology, evolution and conservation. The climatic niche reflects the set of temperature and precipitation conditions where a species can occur. Thus, specialization to a limited set of climatic conditions can be important for understanding patterns of biogeography, species richness, community structure,...

2010
R. K. Rai Alka Upadhyay S. P. Ojha

Identification of the precise nature and attributes of the time series of climatological data is very important and is usually the first step for water resources planning and management. Such exercise is very important for hydro-climatic extremes. In many instances, a climatic time series is generally not statistically independent but is comprised of patterns of persistence, cycles, trends or s...

2012
M. MOYO P. DORWARD

Farmers in semi-arid Zimbabwe prioritise climate variability as their major agricultural productivity-reducing problem. This paper raises the importance of considering local farmers’ perceptions on climate risk, as this greatly influences on-farm investments and decision-making in agricultural management and production in semiarid Zimbabwe. A study was conducted in two districts of semi-arid Zi...

Journal: :Science 1974
P Thompson H P Schwarcz D C Ford

Speleothems from continental North American caves have been dated by means of the (230)Th/(234)U method. Oxygen isotopic variations in the dated samples and phases of speleothem deposition can be interpreted in terms of climatic change. A glacial chronology constructed from the age and isotopic data lends support to the astronomical theory of climatic change.

2011
Craig Loehle Nicola Scafetta

It can be argued that estimation of periodic signals in climate data requires either spectral methods or very long time series, or both. For obtaining a very precise estimate of signal properties this may be true, but for estimating periodicity to within plus or minus a few years, this is not true. To illustrate, we replicate the procedure used in the main manuscript. We take the model from Fig...

2007
R. A. Calvo H. D. Navone

Artificial neural networks are parallel computational algorithms which can simulate very efficiently complex dynamical systems. In this work we show, by means of real-world applications, that this technique can be a useful tool in the analysis of time-series data related to climate. We study two time series: the first one characterizes the solar activity as measured by the annual mean value of ...

2002
V. Demyanov M. Kanevsky S. Chernov E. Savelieva V. Timonin

Direct Neural Network Residual Kriging (DNNRK) is a two step algorithm (Kanevsky et al. 1995). The first step includes estimating large scale structures by using artificial neural networks (ANN) with simple sum of squares error function. ANN, being universal approximators, model overall non-linear spatial pattern fairly well. ANN are model free estimators and depend only on their architecture a...

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