414 research outputs found
El Tlacuache Núm. 624 (2014). 624 Año 13 (2014) junio. El Tlacuache
No full textLa Empatía: Fundamentos teóricos, medición, estimulación, y su percepción social por Marte E. Roel Lesur. - El cóndor del sur y el águila de norte en resistencia por Georgina Galván Medina
Semi-autonomous revenue authorities in Sub-Saharan Africa: Silver bullet or white elephant
No full textSemi-autonomous revenue authorities (SARAs) have been at the centre of tax administration reform in Sub-Saharan Africa for the last 30 years. Nevertheless, the revenue effect of this reform remains highly debated (Ahlerup et al., 2015; Ebeke et al., 2016; Fjeldstad and Moore, 2009; Sarr, 2016; Von Haldenwang et al., 2014). This paper adds to the debate by controlling for the dynamics in tax revenue, which otherwise confound the effect of SARAs on tax revenue. Using a panel dataset of 46 countries over the period 1980-2012 and accounting for revenue dynamics, we show that, in contrast to previous findings, there is no robust evidence that SARAs have increased revenue performance in Sub-Saharan Africa. These findings are supported by an instrumental variable estimation which relies on donor influence. When broadening our scope, we fail to find any effect from SARAs on tax effort, revenue volatility and corruption. We, thus, conclude that there is little statistical support for a systematic relationship between semi-autonomous revenue authorities and tax capacity in Sub-Saharan-Africa
Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands
No full textDissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal a
ffinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal a
ffinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters
are strongly related to EDTA concentrations (R2= 0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.Stijn Baken, Fien Degryse, Liesbeth Verheyen, Roel Merckx, and Erik Smolder
Oorsprong, dynamiek en eigenschappen van opgeloste organische koolstofverbindingen in de bodem.
No full textThe dissolved organic matter (DOM) is the term used for organic components of natural origin present in the soil solution. It is a complex mixture of molecules, generally dominated by humic substances. The DOM is a small fraction (< 1%) of the soil organic matter (SOM), however DOM is supposed to be the most mobile and probably the most reactive fraction. Consequently, it plays an important role in the biogeochemistry of the elements it contains (C, N, P, S,
) and the transport of heavy metals and organic pollutants with a high affinity for organic matter. Since biodegradation is mediated through the aqueous phase, DOM is supposed to be the most bioavailable organic matter pool. Understanding of organic matter cycling and of DOM-facilitated transport of solutes in mineral soils requires information about the origin and dynamics of DOM. The main goal of this research is to unravel the source and the dynamics of DOM in agricultural soils.No standard method exists to sample soil solution. Therefore dissolved organic carbon (DOC) concentration and quality in soil is operationally defined. Effluents of undisturbed soil columns of an agricultural Luvisol contained significantly less DOC than corresponding soil centrifugates (10 versus 20 mg C l-1). In contrast, inorganic solute concentrations did not vary between both sampling methods. The difference in DOC concentrations between both sampling methods did not depend on the water flow rate in the columns. Furthermore, the DOM in the centrifugates was less aromatic than the DOM in the leachates. All this suggests that the larger DOC concentration in centrifugates is unrelated to DOC concentration gradients in the pore matrix but that it is likely released from a fraction of the microbial biomass that is disrupted during centrifugation. Spectroscopic properties of DOM in the samples corroborate this suggestion. Hence, DOM in effluents of undisturbed soil columns is likely most representative of in situ soil DOM.The effect of varying soil properties and pre-treatments on the quantity and quality of DOC in the centrifuged soil solutions was investigated in an explorative study of 87 European agricultural soils. Soil solution DOC concentrations ranged between 12 and 104 mg C l-1 (10th - 90th percentile), median 33 mg C l-1. In freshly sampled agricultural soils, DOC was only weakly explained by soil properties whereas correlations were somewhat stronger in soils that had been equilibrated by incubation or cold storage before analysis. Overall, DOC concentrations weakly increased with increasing % soil organic carbon and decreased with increasing pH. The storage conditions affected DOC concentration and composition: rewetting dry soils released DOM with a low aromaticity that probably originated from decaying biomass rather than from humified organic matter.The source and dynamics of DOM in an agricultural soil after plant residue amendment were studied in a batch experiment. It revealed that residue applicationreleased a pulse of hydrophilic DOC that temporarily (< 3 days) dominated the soil DOM pool and the degradable organic matter. However, beyond that pulse the majority of DOM was derived from soil organic matter. The isotope signature of DOC differed from the isotope signature of microbial biomass C and respired C. This casts doubt that DOC measured in the soil solution represents the major bioavailable soil C pool.The source, dynamics and transport of DOM were subsequently studied in column experiments. First of all, the mechanisms of DOM release were investigated by leaching undisturbed soil columns and applying stop flows. Secondly, the sorption and mineralisation of DOM were examined by adding a 13C labelled DOM pulse to the columns. The release of DOM during leaching was controlled by two different processes. The baseline concentration of DOC in soil solutions was buffered and was independent of the water flow rate. An additional amount of DOC can be released by desorption, diffusion from micro- to macropores or lysis of microbial cells. These processes are kinetically controlled and the additional DOC concentration hence depends on the water fluxes. In agreement with the batch experiments, largest DOC concentrations were found at flow initiation after soil drying. This low aromaticity DOM mainly originated from decaying biomass. A plant derived DOM solution was very quickly and almost completely mineralised during transport through the soil.The results of the laboratory experiments were linked with those of a field trial, to interpret monitoring data of DOM leaching in an arable field subjected to 4 different land management treatments, i.e. conventional tillage, reduced tillage, waste water irrigation and manure application. Leachates were collected at 45 cm depth by passive capillary wick samplers. Over 95% of leachates collected during three successive years contained between 4 and 20 mg DOC l-1 and on average 32 kg DOC ha-1 y-1 was leached. The most consistent findings of the laboratory experiments were also observed in the field. The export of DOC (kg DOC ha-1 y-1) was mainly determined by the water flux, while no correlation was found between the water flow and DOC concentrations. At high water velocities, soil solutions contained small DOC concentrations, while DOC concentrations in soil solutions flowing at low water velocities varied largely. A baseline DOC concentration independent of water flow rates was observed. The largest DOC concentrations however, were inversely proportional to the mean water velocity between succeeding samplings. This indicates that the release of additional DOM is kinetically controlled. Higher concentrations were mostly found in the first leachates collected after a dry period and those solutions mainly contained DOM with a low aromaticity. The effect of environmental conditions and land management practices on DOC concentration or its spectroscopic properties was rather small.A model consisting of twotypes of DOM in aseven pool concept (labile and stable SOM, labile and stable DOM, microbial biomass, plant residues and CO2) summarised the most important findings and captured the general patterns in DOM dynamics rather well. Degradation reactions between the pools were described with first order kinetic reactions and the dynamic equilibrium between DOM and SOM pools was determined by a soil:solution distribution coefficient. The transport of DOM was described by the convection dispersion equation. It was found that soil solutions always contained a constant concentration of relatively stable, not easily degradable organic matter. The concentration of labile DOC was variable and depended on the water velocity, flow interruptions and the presence of plant residues.It can be concluded that soil solution DOM mainly originates from rather stable, more humified soil organic matter. This baseline DOM concentration is highly buffered and may depend on physicochemical soil properties. Flow interruptions or amending the soil with plant residues releases additional DOM. This extra DOM is very labile and quickly mineralised by the microbial biomass. Consequently, it will probably not reach deeper soil layers.status: Publishe
Metal-Metal Cooperativity in Well-defined Dinuclear Complexes; Understanding the Reactivity of Dicopper and Dicobalt Complexes Using the PNNP Expanded Pincer Ligand
No full textThis datapackage contains one PDF file containing the supporting information for the experimental chapters of the PhD thesis: "Metal-Metal Cooperativity in Well-defined Dinuclear Complexes; Understanding the Reactivity of Dicopper and Dicobalt Complexes Using the PNNP Expanded Pincer Ligand"
Author: Roel L. M. Bienenmann
Co-promotor: Daniël L. J. Broere
Promotor: Robertus J. M. Klein Gebbink
For each experimental chapter there is a seperate folder containing the files which contain the spectroscopic and computational data corresponding to these chapters. Some of these overlap with the datapackages from the papers on which the chapters are based. These datapackages of publications are mentioned below in the meta-data
Semi-Autonomous Revenue Authorities in Sub-Saharan Africa: Silver Bullet or White Elephant
No full textEssays on tax, accountability and fiscal capacity in sub-Saharan Africa
No full textThis thesis consists of three self-contained essays exploring the interaction between fiscal capacity and state-building, as well as the impact of external relations on fiscal capacity in sub-Saharan Africa.
The first essay (Chapter 2) explores the links between taxation and accountability improvements. Historical experiences connect taxation with improved government accountability through tax bargaining. However, for contemporary developing countries the validity of this argument is less clear. Using new governance data, I test this hypothesis in a panel of 47 African countries from 1980 until 2015. I show that taxation and accountability are still positively correlated. This effect is mainly driven by direct taxation. Instrumenting tax revenue, with terms of trade and exchange rate shocks, confirms the results. This suggests a causal interpretation for the relationship.
The second essay (Chapter 3) estimates the revenue effect from the introduction of semi-autonomous revenue authorities (SARAs). A major component of international tax reform in sub-Saharan Africa for the last 30 years has been the creation of SARAs. The core argument of this essay is that existing research suggesting diverse and contradictory outcomes has not taken account of trends in revenue performance in the years before the establishment of SARAs. Allowing for this revenue history our analysis based on 46 countries over the period 1980-2015 provides no robust evidence that SARAs induce an increase (or a decrease) in revenue performance.
The third essay (Chapter 4) describes how Burundi used its fiscal policy to counteract the fiscal effects of the suspension of aid. Economic sanctions, and the suspension of budget support in particular, are supposed to pressure target governments to comply with donors' demands by putting spending commitments at risk. The essay argues that this is too simplistic since governments have more fiscal levers at their disposal. Using monthly data on Burundi's fiscal position between 2005 and 2017, the chapter presents evidence from a time series analysis showing that aid does not affect spending because aid shortfalls are compensated with domestic borrowing
Essays on tax, accountability and fiscal capacity in sub-Saharan Africa
No full textThis thesis consists of three self-contained essays exploring the interaction between fiscal capacity and state-building, as well as the impact of external relations on fiscal capacity in sub-Saharan Africa.
The first essay (Chapter 2) explores the links between taxation and accountability improvements. Historical experiences connect taxation with improved government accountability through tax bargaining. However, for contemporary developing countries the validity of this argument is less clear. Using new governance data, I test this hypothesis in a panel of 47 African countries from 1980 until 2015. I show that taxation and accountability are still positively correlated. This effect is mainly driven by direct taxation. Instrumenting tax revenue, with terms of trade and exchange rate shocks, confirms the results. This suggests a causal interpretation for the relationship.
The second essay (Chapter 3) estimates the revenue effect from the introduction of semi-autonomous revenue authorities (SARAs). A major component of international tax reform in sub-Saharan Africa for the last 30 years has been the creation of SARAs. The core argument of this essay is that existing research suggesting diverse and contradictory outcomes has not taken account of trends in revenue performance in the years before the establishment of SARAs. Allowing for this revenue history our analysis based on 46 countries over the period 1980-2015 provides no robust evidence that SARAs induce an increase (or a decrease) in revenue performance.
The third essay (Chapter 4) describes how Burundi used its fiscal policy to counteract the fiscal effects of the suspension of aid. Economic sanctions, and the suspension of budget support in particular, are supposed to pressure target governments to comply with donors' demands by putting spending commitments at risk. The essay argues that this is too simplistic since governments have more fiscal levers at their disposal. Using monthly data on Burundi's fiscal position between 2005 and 2017, the chapter presents evidence from a time series analysis showing that aid does not affect spending because aid shortfalls are compensated with domestic borrowing
Reforming tax systems in the developing world: What can we learn from the past?
No full textThere are questions to be asked about the wisdom of spending more aid on tax. Is it simply the case that the nature of current support and the way in which it is delivered is adequate, but that there is just not enough of it? If so, all that is needed is more of the same. Or, do we also need to rethink both the content and approach to international tax advice? One way of supporting more critical deliberation over the nature of technical cooperation is to better understand how ideas have evolved as well as the lessons that have been learnt (and not learnt) from past efforts to strengthen tax systems. This paper adds to the discussion by providing an accessible summary of the key academic ideas and policy debates over the past century that have shaped the nature of technical cooperation on tax system reforms in developing countries. It then connects these debates with the direction of travel of international cooperation on taxation
The European single market: Restarting the perpetual revolution
No full textThe single market is the European Union's most powerful economic asset, yet persistent barriers continue to undermine its potential. We argue that realising that potential requires a dual strategy: strengthening compliance with existing rules and advancing targeted harmonisation where regulatory gaps persist. Despite recent efforts, compliance outcomes have stagnated while formal enforcement has weakened, possibly reflecting institutional shortcomings. On harmonisation, we highlight key areas, particularly services and regulated professions, for which new legislation is urgently needed, while recognising that politically sensitive fields will require gradual, coordinated progress. We also assess the European Commission's 2025 Single Market Strategy, which takes welcome steps in areas such as construction and telecommunication, but falls short of addressing structural weaknesses in enforcement and offering a bold regulatory vision. We identify four types of barrier that demand tailored responses: stronger enforcement in areas with existing rules, deeper harmonisation where partial integration persists, incremental convergence in minimally harmonised sectors, and facilitated voluntary alignment in politically sensitive areas. Delivering on these priorities is essential to unlock the single market's full potential and secure Europe's long-term competitiveness
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