|
|
|
| Registros recuperados: 30 | |
|
|
| Sexto Monroy, Benjamín. |
| En el presente trabajo se implementa la modelación de valores extremos con la metodolog ía "block maxima", específicamente en niveles m áximos diarios de ozono de la estaci ón Pedregal de la Cd. de M éxico de los años 2001 a 2008, usando la distribución Dagum que es de cola pesada y es usada generalmente como distribuci ón de ingreso, pero tiene un antecedente en el campo meteorol ógico, donde fue usado para modelar la cantidad de precipitaci ón pluvial. Una visualizaci ón general de los datos, hecha gr áficamente, revela una tendencia a la baja de los niveles m áximos diarios de ozono, por lo cual se decide realizar el an álisis por año. Mediante la prueba de Kolmogorov-Smirnov se prueba si las observaciones de cada año siguen la distribución Dagum. El... |
|
Palavras-chave: Tendencia; Ozono; Valor Extremo; VGAM; Trends; Ozone; Extreme Value; Maestría; Estadística. |
| Ano: 2010 |
URL: http://hdl.handle.net/10521/364 |
| |
|
|
| Sexto Monroy, Benjamin. |
| En el presente trabajo se implementa la modelación de valores extremos con la metodolog ía "block maxima", específicamente en niveles m áximos diarios de ozono de la estaci ón Pedregal de la Cd. de M éxico de los años 2001 a 2008, usando la distribución Dagum que es de cola pesada y es usada generalmente como distribuci ón de ingreso, pero tiene un antecedente en el campo meteorol ógico, donde fue usado para modelar la cantidad de precipitaci ón pluvial. Una visualizaci ón general de los datos, hecha gr áficamente, revela una tendencia a la baja de los niveles m áximos diarios de ozono, por lo cual se decide realizar el an álisis por año. Mediante la prueba de Kolmogorov-Smirnov se prueba si las observaciones de cada año siguen la distribución Dagum. El... |
|
Palavras-chave: Tendencia; Ozono; Valor Extremo; VGAM; Trends; Ozone; Extreme Value; Maestría; Estadística. |
| Ano: 2010 |
URL: http://hdl.handle.net/10521/364 |
| |
|
|
| Carrillo Negrete, Oswaldo Ismael. |
| En este trabajo se modela el número de huracanes y su asociación con la Temperatura de la Superficie Marina (SST por sus siglas en ingles), mediante un Proceso Poisson No Homogéneo (PPNH). Se utilizaron métodos no paramétricos y paramétricos, los cuales estiman la función de intensidad del proceso. En las aproximaciones no paramétricas se utilizaron Núcleos y Onduletas. En el caso de los métodos paramétricos se proponen dos modelos, el primero modela el número de huracanes basado en una función exponencial polinomial y el segundo se basa en un PPNH bidimensional en función de la covariable SST. En ambas estimaciones paramétricas se verificaron los supuestos de exponencialidad e independencia. Con la finalidad de ilustrar la aplicabilidad del modelo propuesto,... |
|
Palavras-chave: Proceso poisson; Tendencias; Ciclones tropicales; Actividad ciclónica; Poisson process; Trends; Tropical cyclones; Cyclonic activity; Maestría; Estadística. |
| Ano: 2010 |
URL: http://hdl.handle.net/10521/248 |
| |
|
|
| Guillén Alvarado, Rosa Angélica. |
| En este trabajo consiste en realizar una predicción de precios del huevo en México con datos de 1960 a 2003 y posteriormente se obtuvo la predicción de precios hasta el 2007, mismo que se tomas los precios nominales del huevo y el índice nacional de precios al consumidor para calcular los precios reales y obtener la desestacionalización de los precios, posteriormente con el apoyo del programa de SAS, se establece un modelo econométrico con el que se calcula la tendencia de mejor ajuste. El modelo cuadrático tiene un buen ajuste dado por el coeficiente de determinación (R2 =0.9432) y sus parámetros de acuerdo con la razón de t son significativos al 99% de probabilidad. Tomando en consideración la tendencia estimada, el índice estacional, el índice cíclico... |
|
Palavras-chave: Ciclos; Huevo; Tendencia; Predicción de precios; Cycles; Egg; Trends; Price forecast; Economía; Maestría. |
| Ano: 2012 |
URL: http://hdl.handle.net/10521/1706 |
| |
|
|
| Roubik, David Ward; Smithsonian Tropical Research Institute; roubikd@tivoli.si.edu. |
| Plant-pollinator systems inherently possess wide variation that limits the applicability of surveys on population dynamics or diversity. Stable habitats are scarcely studied, whereas dynamics in unprotected habitats are less predictable or more compromised by exotic organisms (Apis, in the case of bee surveys). An extensively replicated, long-term study of orchid-bees (Euglossini) was made in protected tropical moist forest in Panama. Over 47,000 bees were recorded in 124 monthly censuses employing 1952 counts. No aggregate trend in abundance occurred (from 1979 to 2000), although four individual species declined, nine increased, 23 showed no change, and species richness was stable. No rare or parasitic species showed decreasing trends, while the most... |
| Tipo: Peer-Reviewed Reports |
Palavras-chave: ENSO; Euglossini; Abundance variability; Bees; Census techniques; Diversity; Pollinators; Trends; Tropical- temperate comparisons. |
| Ano: 2001 |
|
| |
|
| |
|
|
| Dauer, Dm. |
| Long-term trends in subtidal macrobenthic communities of the lower Chesapeake Bay, USA, were examined using data collected quarterly (March, June, September and December) fr om 1985 through 1993 at 16 stations along a salinity gradient from tidal freshwater regions of the major tributaries (James, York and Rappahannock rivers) to the polyhaline region of the mainstem of Chesapeake Bay. In March 1989 two stations were added to the program in the mesohaline region of the Southern Branch of the Elizabeth River, a region characterized by contaminated sediments. A non-parametric trend analysis procedure was applied to five parameters characterizing macrobenthic community structure: community biomass, species richness, abundance of individuals, proportion of... |
| Tipo: Text |
Palavras-chave: Chesapeake Bay; Benthos; Trends; Estuary; Eutrophication. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20399/18066.pdf |
| |
|
|
| Galgani, Francois; Brien, Aleke Stoefen-o; Weis, Judith; Ioakeimidis, Christos; Schuyler, Qamar; Makarenko, Iryna; Griffiths, Huw; Bondareff, Joan; Vethaak, Dick; Deidun, Alan; Sobral, Paula; Topouzelis, Konstantinos; Vlahos, Penny; Lana, Fernanda; Hassellov, Martin; Gerigny, Olivia; Arsonina, Bera; Ambulkar, Archis; Azzaro, Maurizio; Bebianno, Maria João. |
| Whilst both plastic production and inputs at sea have increased since the 1950s, several modelling studies predict a further increase in the coming years in these respective quantities. We compiled scientific literature on trends in marine litter, consisting largely of plastic and microplastics in the ocean, understanding that monitoring programs or assessments for these aspects are varied, frequently focusing on limited components of the marine environment in different locations, and covering a wide spectrum of marine litter types, with limited standardization. Here we discuss how trends in the amounts of litter in the marine environment can be compared with the information provided by models. Increasing amounts of plastic are found in some regions,... |
| Tipo: Text |
Palavras-chave: Plastic pollution; Marine litter; Microplastics; Trends; Monitoring. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00677/78927/81297.pdf |
| |
|
|
| Alden, Rw. |
| A long-term water quality monitoring program has been established in the Virginian waters of the Chesapeake Bay. To date, over eight years of data have been analyzed to characterize spatio-temporal patterns and long-term trends in water quality. Complementary multivariate statistical procedures were employed to define spatial and seasonal patterns, while a series of non-parametric trend analyses were used for determining overall, site-specific, and season-specific long-term trends for water quality variables in the tributaries and mainstem of the Bay. Particular attention was focused on determining the effect of river flow on the trends, because flow rates in some of the tributaries have changed dramatically since the beginning of the monitoring program.... |
| Tipo: Text |
Palavras-chave: Water quality; Monitoring; Statistics; Trends; Flow. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20461/18133.pdf |
| |
|
|
| Peristeraki, Panagiota; Bitetto, Isabella; Carbonara, Pierluigi; Carlucci, Roberto; Certain, Gregoire; De Carlo, Francesco; Gristina, Michele; Kamidis, Nikos; Pesci, Paola; Stagioni, Marco; Valls, María; Tserpes, George. |
| Mean temperature (MTC) and mean trophic level (MTL) spatiotemporal patterns of MEDITS survey catches were examined in 13 geographic statistical areas (GSAs) of the Mediterranean between 1994 and 2016. The study aimed to detect changes in the demersal community structure related to anthropogenic impacts. A generalized additive modelling approach was used to examine the effects of year and GSA on the MTC and MTL indexes and on bottom temperature by haul. For the MTC index, the year was significant only in 4 GSAs, while for MTL it was significant in 5. Higher MTC values were observed in central and eastern areas. Bottom temperature increased after 2010, and also from west to east and from north to south. Our results indicate that the recently observed... |
| Tipo: Text |
Palavras-chave: Mean temperature of the catch; Trophic level; Bottom temperature; Trends; Mediterranean; Fishing pressure; Sea warming; Climate change. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60054/63332.pdf |
| |
|
|
| Ritter, R.; Landschuetzer, P.; Gruber, N.; Fay, A. R.; Iida, Y.; Jones, S.; Nakaoka, S.; Park, G. -h.; Peylin, P.; Roedenbeck, C.; Rodgers, K. B.; Shutler, J. D.; Zeng, J.. |
| The Southern Ocean (SO) carbon sink has strengthened substantially since the year 2000, following a decade of a weakening trend. However, the surface ocean pCO(2) data underlying this trend reversal are sparse, requiring a substantial amount of extrapolation to map the data. Here we use nine different pCO(2) mapping products to investigate the SO trends and their sensitivity to the mapping procedure. We find a robust temporal coherence for the entire SO, with eight of the nine products agreeing on the sign of the decadal trends, that is, a weakening CO2 sink trend in the 1990s (on average 0.22 0.24pgCyr(-1)decade(-1)), and a strengthening sink trend during the 2000s (-0.35 0.23pgCyr(-1)decade(-1)). Spatially, the multiproduct mean reveals rather uniform... |
| Tipo: Text |
Palavras-chave: Southern Ocean; CO2; Observations; SOCOM; Trends; Carbon sink. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00662/77387/79013.pdf |
| |
|
|
| Tserpes, George; Massutí, Enric; Fiorentino, Fabio; Facchini, Maria Teresa; Viva, Claudio; Jadaud, Angelique; Joksimovic, Aleksandar; Pesci, Paola; Piccinetti, Corrado; Sion, Letizia; Thasitis, Ioannis; Vrgoc, Nedo. |
| The present work examines the spatio-temporal biomass trends of Mullus barbatus and Mullus surmuletus in the Mediterranean Sea through the analysis of a time series of data coming from the Mediterranean International Trawl Surveys (MEDITS), accomplished annually from 1994 to 2015. The biomass of both species showed clear declining trends below 150 to 200 m depth, which were steeper in the case of M. barbatus. Increases in temporal biomass trends were observed for M. barbatus from 2008 onward in most geographic sub-areas (GSAs), while stability was mostly observed for M. surmuletus. For both species, dynamic factor analysis revealed similarities among neighbouring GSAs and the subsequent cluster analysis identified two major GSA groups corresponding to the... |
| Tipo: Text |
Palavras-chave: Red mullet; Striped red mullet; Distribution; Trends; Mediterranean. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00489/60056/63336.pdf |
| |
|
|
| Firing, Yvonne L.; Mcdonagh, Elaine L.; King, Brian A.; Desbruyeres, Damien. |
| Observations made on 21 occupations between 1993 and 2016 of GO-SHIP line SR1b in eastern Drake Passage show an average temperature of 0.53 degrees C deeper than 2000 dbar, with no significant trend, but substantial year-to-year variability (standard deviation 0.08 degrees C). Using a neutral density framework to decompose the temperature variability into isopycnal displacement (heave) and isopycnal property change components shows that approximately 95% of the year-to-year variance in deep temperature is due to heave. Changes on isopycnals make a small contribution to year-to-year variability but contribute a significant trend of -1.40.6 m degrees C per year, largest for density ((n))>28.1, south of the Polar Front (PF). The heave component is... |
| Tipo: Text |
Palavras-chave: Temperature; Trends; Southern Ocean. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00387/49812/50390.pdf |
| |
|
|
| Coll, M.; Shannon, L. J.; Kleisner, K. M.; Juan-jorda, M. J.; Bundy, A.; Akoglu, A. G.; Banaru, Daniela; Boldt, J. L.; Borges, M. F.; Cook, A.; Diallo, I.; Fu, C.; Fox, C.; Gascuel, D.; Gurney, L. J.; Hattab, T.; Heymans, J. J.; Jouffre, D.; Knight, B. R.; Kucukavsar, S.; Large, S. I.; Lynam, C.; Machias, A.; Marshall, K. N.; Masski, H.; Ojaveer, H.; Piroddi, C.; Tam, J.; Thiao, D.; Thiaw, M.; Torres, M. A.; Travers-trolet, Morgane; Tsagarakis, K.; Tuck, I.; Van Der Meeren, G. I.; Yemane, D.; Zador, S. G.; Shin, Y. -j.. |
| IndiSeas (“Indicators for the Seas”) is a collaborative international working group that was established in 2005 to evaluate the status of exploited marine ecosystems using a suite of indicators in a comparative framework. An initial shortlist of seven ecological indicators was selected to quantify the effects of fishing on the broader ecosystem using several criteria (i.e., ecological meaning, sensitivity to fishing, data availability, management objectives and public awareness). The suite comprised: (i) the inverse coefficient of variation of total biomass of surveyed species, (ii) mean fish length in the surveyed community, (iii) mean maximum life span of surveyed fish species, (iv) proportion of predatory fish in the surveyed community, (v) proportion... |
| Tipo: Text |
Palavras-chave: Ecological indicators; Marine ecosystems; Biodiversity; Redundancy; Trends; States; Fishing impacts; Conservation. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00281/39201/37902.pdf |
| |
|
| |
|
|
| Marshall, Hg; Alden, Rw. |
| Long term trends in the phytoplankton of the lower Chesapeake Bay were identified using flow corrected and uncorrected data sets, with 22 of 23 significant trends similar under both conditions. The major trends between 1985-1992 were for: 1) reduced phytoplankton concentrations; 2) decreasing numbers of phytoplankton taxa during spring, summer and fall months; and 3) seasonally mixed trends for diatom abundance in waters below the pycnocline, with spring months having decreasing densities, and increasing abundance trends in November and December. The flow patterns had different effects on the trends. Flow diminished the magnitude of the trends for total phytplankton concentrations, so these trends were greater in the flow corrected data. There were mixed... |
| Tipo: Text |
Palavras-chave: Phytoplankton; Chesapeake Bay; Trends; Flow. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00093/20383/18051.pdf |
| |
|
|
| Peeters, T.M.J.; Reemer, M.. |
| Bedreigde en verdwenen bijen in Nederland (Apidae s.l.) basisrapport met voorstel voor de rode lijst Dit rapport bevat het voorstel voor een Rode Lijst van de Nederlandse bijen (Apidae s.l.). De Rode Lijst werd samengesteld door Stichting EIS-Nederland in opdracht van het Ministerie van Landbouw, Natuurbeheer en Visserij. De Rode-Lijststatus is bepaald aan de hand van een combinatie van een zeldzaamheids- en een trendcriterium. De zeldzaamheid werd bepaald met het aantal atlasblokken (5x5 km) waarin een soort is aangetroffen in de periode 1970-2001 (actuele periode). De trend werd bepaald door de status in de actuele periode te vergelijken met de status in de periode voor 1970 (referentieperiode). Van de 338 in Nederland aangetroffen bijensoorten komen... |
| Tipo: Book (monograph) |
Palavras-chave: Nederland; Verspreiding; Beschermin; Trends; Rode lijst; 42.75. |
| Ano: 2003 |
URL: http://www.repository.naturalis.nl/record/220052 |
| |
|
|
| Bruyne, R. de; Wallbrink, H.; Gmelig Meyling, A.. |
| Bedreigde en verdwenen land- en zoetwaterweekdieren in Nederland (Mollusca) basisrapport met voorstel voor de rode lijst Dit rapport bevat het voorstel voor een Rode Lijst voor Nederlandse terrestrische en aquatische weekdieren. Voor de vertegenwoordigers van het fylum Mollusca wordt behalve de naam ‘weekdieren’, ook ‘mollusken’ gebruikt, of ‘schelpdieren’. In de lijst is een onderverdeling gemaakt in terrestrische mollusken (landslakken) en aquatische mollusken (waterslakken en twee– kleppigen). In de laatste categorie vallen alle soorten uit zoet, binnendijks water. De mariene aquatische soorten zijn, uitgezonderd enkele in binnendijks brak water voorkomende soorten, buiten beschouwing gebleven. Indien gesproken wordt van aquatische mollusken, wordt... |
| Tipo: Book (monograph) |
Palavras-chave: Nederland; Rode lijst; Bescherming; Trends; 42.73. |
| Ano: 2003 |
URL: http://www.repository.naturalis.nl/record/219874 |
| |
|
|
| Reemer, M.; Smit, J.T.; Steenis, W. van. |
| Changes in ranges of hoverflies in the Netherlands in the 20th century (Diptera: Syrphidae) In July 2001 the database of the Netherlands Syrphidae Recording Scheme contained approximately 200 000 records of Syrphidae. This database was used to examine changes in the hoverfly fauna of the Netherlands during the 20th century. The dataset was divided into two parts, before and since 1988, containing equal numbers of records. This revealed that there is a significant increase in the distribution of hoverfly species with saproxylic larvae. Probably this is a consequence of the changes in woodland management that have taken place in the past 20 years. Another result of the trend analysis is the conclusion that there is a high proportion of southern species... |
| Tipo: Article in monograph or in proceedings |
Palavras-chave: Syrphidae; Trends; Netherlands; Saproxylic species; Climate change; 42.75. |
| Ano: 2003 |
URL: http://www.repository.naturalis.nl/record/219854 |
| |
|
|
| Gonseth, Y.; Monnerat, C.. |
| Recent changes in distribution of dragonflies in Switzerland (Odonata) In 1998 the Swiss Centre for the Cartography of Fauna (CSCF) initiated ‘Odonata 2000’. This project aimed at testing a method for periodical reassessment of Red Lists in Switzerland. The study was carried out on Odonata and consisted of the resampling of known localities of threatened species and the sampling of new localities. Based on the number of sites where a given species has been found in the periods 1970-1998 and 1999-2000, trends were calculated for each species. The results show that since 1994 three species have disappeared from Switzerland, nine species have declined, two species have increased and 64 species have remained stable. Crocothemis erythraea, Lestes virens,... |
| Tipo: Article in monograph or in proceedings |
Palavras-chave: Odonata; Switzerland; Faunistics; Red list; Conservation; Trends; 42.75. |
| Ano: 2003 |
URL: http://www.repository.naturalis.nl/record/219850 |
| |
| Registros recuperados: 30 | |
|
|
|
