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Search Results: 1 - 10 of 2499 matches for " Karina; Douglass "
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Population ecology of Eligmodontia morgani (Rodentia, Cricetidae, Sigmodontinae) in northwestern Patagonia
Monteverde,Martín; Piudo,Luciana; Hodara,Karina; Douglass,Richard;
Ecolog?-a austral , 2011,
Abstract: eligmodontia morgani is one of the most abundant endemic species of arid patagonian steppe. most previous studies have focused on systematics and taxonomy and ecological information on this species is scarce. the objectives of this study were to estimate population parameters for e. morgani in the patagonian steppe ecoregion and to compare them to parameters available for this species in another environment. data were collected from february 2003 through october 2004. abundances ranged from 12±1.85 to 71±6.67, with residents comprising 39% of the population. the sex ratio was female biased and age classes resulted in juveniles body mass ≤11 g, subadults between 13-15 g, and adults ≥17g. the breeding season lasted from august to march. the home range sizes were 659.72±90.55 m2 for females and 439.58±114.54 m2 for males. the comparison of present results with those obtained in the subandean district within the patagonian steppe ecoregion showed similar home range sizes and residency but a different proportion of e. morgani in the total number of rodent captures, trap success, and sex ratio. the ability of this species to occupy diverse arid environments of patagonia may evidence a significant ecological niche breadth.
Separation of a Signal of Interest from a Seasonal Effect in Geophysical Data: I. El Niño/La Niña Phenomenon  [PDF]
David H. Douglass
International Journal of Geosciences (IJG) , 2011, DOI: 10.4236/ijg.2011.24045
Abstract: Geophysical signals N of interest are often contained in a parent signal G that also contains a seasonal signal X at a known frequency fX. The general issues associated with identifying N and X and their separation from G are considered for the case where G is the Pacific sea surface temperature monthly data, SST3.4; N is the El Niño/La Niña phenomenon and the seasonal signal X is at a frequency of 1/(12 months). It is shown that the commonly used climatology method of subtracting the average seasonal values of SST3.4 to produce the widely used anomaly index Nino3.4 is shown not to remove the seasonal signal. Furthermore, it is shown that the climatology method will always fail. An alternative method is presented in which a 1/fX (= 12 months) moving average filter F is applied to SST3.4 to generate an El Niño/La Niña index NL that does not contain a seasonal signal. Comparison of NL and Nino3.4 shows, among other things, that estimates of the relative magnitudes of El Niños from index NL agree with observations but estimates from index Nino3.4 do not. These results are applicable to other geophysical measurements.
Observation of Phase-Locked States in the Atlantic Multi-Decadal Oscillation (AMO)  [PDF]
David Holmes Douglass
Atmospheric and Climate Sciences (ACS) , 2018, DOI: 10.4236/acs.2018.83023
Abstract: We report that the Atlantic Multi-Decadal Oscillation (AMO) shows the same phase-locked states of period 2 and 3 years that have been reported in many other climate indices. In addition, we find that the report by Muller, Curry et al. of an oscillation in the AMO of 9.1 years is a misinterpretation of a maximum in the Fourier spectrum.
When Will the Next El Ni?o Occur?  [PDF]
David Holmes Douglass
Atmospheric and Climate Sciences (ACS) , 2018, DOI: 10.4236/acs.2018.84028
Abstract: There is great interest in knowing when a future El Niño will occur. Most physical models forecast the future based on climate data from the recent past—about a year. The forecasted future is also a fraction of a year. This approach to predicting the future does not use the fact that the climate system may be in a phase-locked state in which sinusoidal oscillations of 2 or 3 years are observed. These states can last many cycles. Thus, if the climate system is in a phase-locked state, one may be able to make definite statements about the future independent of physical models. Douglass, Knox, Curtiss, Geise and Ray (DKCGR) have used the fact that the climate system is presently in a phase-loxked state of period 3 years to state (December 2016) that the next El Niño episode may show a maximum at about November of 2018. We present an updated analysis and state (September 2018) that if the climate system remains in a phase-locked state of period 3 years there will be an El Niño maximum at about November 2018. If that happens, there could be another El Niño maximum at about November 2021.
Recent Energy Balance of Earth  [PDF]
Robert S. Knox, David H. Douglass
International Journal of Geosciences (IJG) , 2010, DOI: 10.4236/ijg.2010.13013
Abstract: A recently published estimate of Earth’s global warming trend is 0.63 ± 0.28 W/m2, as calculated from ocean heat content anomaly data spanning 1993-2008. This value is not representative of the recent (2003-2008) warming/cooling rate because of a “flattening” that occurred around 2001-2002. Using only 2003-2008 data from Argo floats, we find by four different algorithms that the recent trend ranges from –0.010 to –0.161 W/m2 with a typical error bar of ±0.2 W/m2. These results fail to support the existence of a frequently-cited large positive computed radiative imbalance.
The Newest Getter Technologies: Materials, Processes, Equipment  [PDF]
Konstantin Chuntonov, Janez Setina, Gary Douglass
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.39008
Abstract: The efficiency of sorption purification of gases, as measured by an improvement in product quality and/or lowering of its cost, can be significantly increased via simple solutions: the substitution of current getter technology with reactive getters; and stimulation of the material in the sorption process using mechanochemical methods instead of heating or cooling. These ideas were embodied by the authors in new sorption apparatuses and devices such as mechanochemical sorption apparatuses for production of ultra pure gases, improved gas purifiers with reactive sorbent for production of pure and high purity gases and, finally, fluidized bed columns for mass production of pure and high purity gases.
La evolución histórica de las formas de gobierno
North , Douglass C.
Revista de Economía Institucional , 2000,
Abstract: En un ensayo anterior (North, 1981, Cap. 3), expuse una teoría neoclásica del Estado . Este ensayo elabora, amplía y modifica ese ensayo en tres direcciones: 1. Incorpora el tiempo en el modelo; 2. Trata explícitamente las percepciones los sistemas de creencias- que determinan las elecciones; y 3. Relaciona los sistemas de creencias con el ambiente externo de los jugadores; tanto las experiencias ambientales anteriores, que son incorporadas en el condicionando cultural, como las experiencias ambientales del presente, que son incorporadas en el aprendizaje local .
Physical Modelling of Proton and Heavy Ion Radiation using Geant4
Douglass M.,Bezak E.
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123504001
Abstract: Protons and heavy ion particles are considered to be ideal particles for use in external beam radiotherapy due to superior properties of the dose distribution that results when these particles are incident externally and due to their relative biological effectiveness. While significant research has been performed into the properties and physical dose characteristics of heavy ions, the nuclear reactions (direct and fragmentation) undergone by He4, C12 and Ne20 nuclei used in radiotherapy in materials other than water is still largely unexplored. In the current project, input code was developed for the Monte Carlo toolkit Geant 4 version 9.3 to simulate the transport of several mono-energetic heavy ions through water. The relative dose contributions from secondary particles and nuclear fragments originating from the primary particles were investigated for each ion in both water and dense bone (ICRU) media. The results indicated that the relative contribution to the total physical dose from nuclear fragments increased with both increasing particle mass and with increasing medium density. In the case of 150 MeV protons, secondary particles were shown to contribute less than 0.5% of the peak dose and as high as 25% when using 10570 MeV neon ions in bone. When water was substituted for a bone medium, the contributions from fragments increased by more than 6% for C12 and Ne20.
Recognizing Text Genres with Simple Metrics Using Discriminant Analysis
Jussi Karlgren,Douglass Cutting
Computer Science , 1994,
Abstract: A simple method for categorizing texts into predetermined text genre categories using the statistical standard technique of discriminant analysis is demonstrated with application to the Brown corpus. Discriminant analysis makes it possible use a large number of parameters that may be specific for a certain corpus or information stream, and combine them into a small number of functions, with the parameters weighted on basis of how useful they are for discriminating text genres. An application to information retrieval is discussed.
Understanding Civil War Violence through Military Intelligence: Mining Civilian Targeting Records from the Vietnam War
Rex W. Douglass
Computer Science , 2015,
Abstract: Military intelligence is underutilized in the study of civil war violence. Declassified records are hard to acquire and difficult to explore with the standard econometrics toolbox. I investigate a contemporary government database of civilians targeted during the Vietnam War. The data are detailed, with up to 45 attributes recorded for 73,712 individual civilian suspects. I employ an unsupervised machine learning approach of cleaning, variable selection, dimensionality reduction, and clustering. I find support for a simplifying typology of civilian targeting that distinguishes different kinds of suspects and different kinds targeting methods. The typology is robust, successfully clustering both government actors and rebel departments into groups that mirror their known functions. The exercise highlights methods for dealing with high dimensional found conflict data. It also illustrates how aggregating measures of political violence masks a complex underlying empirical data generating process as well as a complex institutional reporting process.
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