Search results for "Lag"

Changes in feeding niche widths of perch and roach following biomanipulation, revealed by stable isotope analysis

2008

Summary 1. We made an empirical test of a recent proposal that feeding niche widths might be determined as variance of stable isotope values. We determined δ13C and δ15N values of perch (Perca fluviatilis), roach (Rutilus rutilus) and their prey from a biomanipulated lake, when the mass removal of fish led to reduced inter- and intra-specific competition and increases in zooplankton abundance and body size. 2. After the first fish removals, both perch and roach mean δ13C values decreased and mean δ15N values increased, indicating a greater diet contribution from pelagic sources. 3. Variances of both δ13C and δ15N values first increased in both fish populations, indicating a wider food spect…

Pelagic food web as the basis of fisheries in Lake Tanganyika: A bioenergetic modeling analysis

2002

Fisheries in Lake Tanganyika, East Africa, are mainly based on two predominantly planktivorous clupeids (Stolothrissa tanganicae and Limnothrissa miodon) and a centropomid predator (Lates stappersi), caught with lift nets, purse seines, and beach seines by traditional, artisanal, and industrial fishers. The biological basis and sustainability of the present fisheries were assessed in a comprehensive project “Research for the Management of the Fisheries on Lake Tanganyika” in 1992–1998. Production in the whole lake was estimated for the entire pelagic food chain leading to the commercially important fish species. Preliminary calculations based on a constant production efficiency suggested th…

2015

Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes…

DETERMINANTS OF EDUCATIONAL ADVANCEMENT OF RURAL AREAS IN POLAND

2017

The article is an aimed attempt at the diagnosis and evaluation of the educational level (character) of rural population in Poland perceived as educational advancement as well as of its environment (background). Growing importance of education in improving professional opportunities, changing educational aspirations and parents’ support as well as positive internal migration trends were emphasised. Rural regions are still lagging behind urban areas, though optimistic characteristics indicate receding stigmatisation and marginalisation of the Polish country with internal migration of young and educated individuals, including affluent ones (potential luxury goods buyers), to rural area…

How do community development activities affect the construction of rural places? : A case study from Finland

2019

Community‐based development practices have been seen as the prevailing paradigm for rural development. Rural community development practices are employed especially through local non‐governmental organisations, such as village associations, to ensure that rural communities are vital and attractive places to live. In this article, we explore how community development practices affect and shape rural places. The data were collected in three Finnish villages that each have an active village association and that have adopted community development practices as their method of keeping their village viable. According to the results of our study, the impacts of community practices on rural places c…

Life cycle assessment of low temperature asphalt mixtures for road pavement surfaces: A comparative analysis

2018

The increasing fuel consumption demand, the accelerated pressure imposed by the depletion of 5 scarce raw materials and the urgent environmental protection requirements are forcing the change of 6 pavement industry and academia community’s research endeavors towards the development of low 7 emissions road paving technologies able to significantly reduce mixing and compaction temperature as 8 well as the consumption of virgin raw materials. One set of relatively recent technologies in the field of 9 pavement materials that aims at addressing those concerns are the warm mix asphalt (WMA). In fact, 10 they have the potential to allow the reduction of energy consumption and airborne emissions d…

Laboratory investigations on co-digestion of energy crops and crop residues with cow manure for methane production: Effect of crop to manure ratio

2007

Abstract Anaerobic co-digestion of grass silage, sugar beet tops and oat straw with cow manure was evaluated in semi-continuously fed laboratory continuously stirred tank reactors (CSTRs). Co-digestion of manure and crops was shown to be feasible with feedstock volatile solids (VS) containing up to 40% of crops. The highest specific methane yields of 268, 229 and 213 l CH4 kg−1 VSadded in co-digestion of cow manure with grass, sugar beet tops and straw, respectively, were obtained with 30% of crop in the feedstock, corresponding to 85–105% of the methane potential in the substrates as determined by batch assays. Including 30% of crop in the feedstock increased methane production per digeste…

Real wages-employment relationship in Finnish manufacturing: a VAR approach

1991

Granger's concept of causality and the vector autoregressive(VAR) technique is used to investigate the real wages-employment relationship in Finnish manufacturing. The stationarity of the time series is examined and a number of co-integration tests for the adequacy of a pure VAR specification performed. The results using a bivariate VAR model based on a lag structure determined by Akaike's information criterion suggests that real wages Granger-cause employment. The slight non-constancy of the model suggests, however, that the conclusion concerning the nature of the real wages-emploment relationship should be treated with causion.

Nonlinear impact estimation in spatial autoregressive models

2018

International audience; This paper extends the literature on the calculation and interpretation of impacts for spatial autoregressive models. Using a Bayesian framework, we show how the individual direct and indirect impacts associated with an exogenous variable introduced in a nonlinear way in such models can be computed, theoretically and empirically. Rather than averaging the individual impacts, we suggest to graphically analyze them along with their confidence intervals calculated from Markov chain Monte Carlo (MCMC). We also explicitly derive the form of the gap between individual impacts in the spatial autoregressive model and the corresponding model without a spatial lag and show, in…

The effects of fiscal policy shocks on the business environment

2021

Fiscal policy influences economic conditions through public spending and taxes, generating positive or negative impulses, both on short and long term. The present research focuses on analysing the effects of the discretionary changes in the fiscal policy in seven post-communist countries of the European Union during the period 2000–2018. The autoregressive distributed lag model (ARDL) has been applied in order to obtain the convergence rates to equilibrium with a clear analysis of the periods needed to achieve the long-run fiscal sustainability. Also, the error correction vector model (VECM), which is based on the autoregressive vector (VAR) model, has been used in the second part of the an…