417 research outputs found
The Procyclical Effects of Bank Capital Regulation
We assess the procyclical effects of bank capital regulation in a dynamic equilibrium model of relationship lending in which banks are unable to access the equity markets every period. Banks anticipate that shocks to their earnings as well as the cyclical position of the economy can impair their capacity to lend in the future and, as a precaution, hold capital buffers. We find that under cyclically-varying risk-based capital requirements (e.g. Basel II) banks hold larger buffers in expansions than in recessions. Yet, these buffers are insufficient to prevent a significant contraction in the supply of credit at the arrival of a recession. We show that cyclical adjustments in the confidence level underlying Basel II can reduce its procyclical effects on the supply of credit without compromising banks’ long-run solvency targets.Banking regulation;Basel II;Business cycles;Capital requirements;Credit crunch;Loan defaults;Relationship banking
Spatial and temporal variability of CO2 emisions in soils under conventional tillage and no-till farming
Agricultural soils can act as a carbon sink depending on the soil management practices employed. As a result of this functional duality, soil management systems are present in international documents relating to climate change mitigation. Agricultural practices are responsible for 14% of total greenhouse gas emissions (GHG’s) (MMA, 2009)(1). Conservation agriculture (CA) is one of the most effective agricultural systems for reducing CO2 emissions, as it increases the sequestration of atmospheric carbon in the soil.
In order to assess the performance of CA in terms of CO2 emissions, a field trial was conducted comparing soil derived CO2 fluxes under No-till (NT) farming and under conventional tillage. Three pilot farms were selected in the cereal-growing area of southern Spain, located in Las Cabezas de San Juan (Seville), Carmona (Seville) and Cordoba. Each pilot farm comprises six experimental plots with an approximate area of five hectares; three of the six plots implement CA practices, while the other three use conventional tillage techniques. The subdivision of each tillage system into 3 plots allowed the simultaneous cropping of the three crops of the wheat-sunflower-legume rotation each year.
Results showed that carbon dioxide emissions were 31 to 91% higher in tilled soils than in untilled soils, and that there was a great seasonal variability of CO2 emissions, as weather conditions also differed considerably for the different sampling periods. In all cases, the CO2 fluxes emitted into the atmosphere were always higher when soil was subject to conventional tillage
Effect of agronomic and environmental factors on CO2 emissions on a dryland rotation
Agriculture is a substantial source of greenhouse gas emissions (GHG) in many countries.
Conservation agriculture includes soil management systems that help to reduce CO2 emission levels.
However, there are many factors involved in the production of these emissions such as soil management type and time at which the agriculture operations are performed, crop phenological state, the weather, and handling of the residue amongst others. In the long term, the relationships that exist between these factors seem to determine the balance of these emissions.
In this study, we analyzed the influence of the soil management system as well as the climatology of the different seasons studied and the phenological state of the different crops implanted.
For this purpose a field trial was conducted in Las Cabezas de San Juán (Seville). This pilot farm consisted of six experimental plots with an approximate area of 5 ha; conservation agriculture practices were employed in three of the six plots while traditional tillage management was used in the other three. Within these plots the three crops of the wheat-sunflower-legume rotation were tested simultaneously.
The study was conducted over four agricultural seasons - 2009/10, 2010/11, 2011/12 and 2012/13.
Each of these cropping seasons were characterised by very different rainfall amounts, registering a total of 814.4, 721.6, 268.2 and 676.4 l/m2, respectively.
When we studied the evolution of emissions over four seasons, an increase could be observed for
both management systems during the time in which the crops were established due to the roots respiration processes. These increases were heavily influenced by the rainfall recorded during the
time in which the crop was in place.
In the case of wheat, higher emissions were produced during the cultivation time of the first and fourth season during which 84% and 60% of the total rainfall of each season was recorded. These emissions were 9 and 5 kg CO2/ha for conventional tillage and no tillage, respectively for the 2009/10 season and 11.7 and 6.8 kg CO2/ha, respectively in the 2012/13 season. Conversely during the 2011/12 season, a season in which lower precipitation was registered, the higher emissions were comparatively minor with respect to the previous values, specifically 3.7 and 1.9 kg CO2/ha for non-tillage and conventional tillage
DMPSA appliCation reduces N2O emissions from exogenous NH4 + and NO3 - sources in irrigated maize
Agriculture is a major anthropogenic source of nitrous oxide (N2O). Application of nitrogenous (N)
fertilizers enhances the emission of this greenhouse gas (GHG), mainly due to the biogenic processes of
nitrification and denitrification. The use of nitrification inhibitors (NIs), that delay the microbial oxidation of
NH4 + to NO3 -, has been reported as a successful tool for mitigating N2O losses. In this context, a field
experiment using 15N labeled fertilizers was carried out in an irrigated Mediterranean maize field aiming to
evaluate the effectiveness of the NI 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture
(DMPSA) on mitigating N2O emissions, and assess the processes involved in its production. The experiment,
performed in 1 m2 microplots, involved the application of 15NH4NO3 or NH4 15NO3 - (with and without DMPSA) to quantify the amount of N2O coming from exogenous NH4 +, exogenous NO3 - and endogenous soil N. The resulting N2O fluxes confirmed that the addition of DMPSA led to a significant (54%) abatement of this GHG. In this experiment, both nitrification and denitrification were partially inhibited by DMPSA.
When NI was not applied, the largest N2O emissions were expected from NH4 + than from NO3 --based fertilizers due to nitrification
Conditional Allocation of Control Rights in Venture Capital Finance
When a young entrepreneurial firm matures, it is often necessary to replace the founding entrepreneur by a professional manager. This replacement decision can be affected by the private benefits of control enjoyed by the entrepreneur which gives rise to a conflict of interest between the entrepreneur and the venture capitalist. We show that a combination of convertible securities and contingent control rights can be used to resolve this conflict efficiently. This contractual arrangement is frequently observed in venture capital finance
Transformación vía Agrobacterium tumefaciens para inducir tolerancia a la podredumbre blanca del aguacate
Comunicación presentada en el VII World Avocado Congress, celebrado en Cairns (Australia) del 5 al 9 de septiembre de 2011.[EN] One of the most important limiting factors for avocado production in Spain is the disease caused by the fungus Rosellinia necatrix . Genetic manipulation could be useful for the introduction of fungal resistance traits into this crop. A n efficient Agrobacterium - mediated transformation protocol for avocado using AGL1 Agrobacterium strain and somatic embryos as the target material has been established by our group, although embryo conversion rate into plants needs to be improved. For that reason, we are using the strawberry, another Rosellinia necatrix ́s host, as model species to test the effect of several transgenes (two of fungal origin, chit 42 chitinase and β - 1,3 - glucanase from Trichoderma harzianum , and one of plant origin, At NPR1), on inducing tolerance to this fungus. Strawberry transformation with the β - 1,3 - glucanase gene has allowed the selection of two lines, β6 and β10, with enhanced tolerance to R. necatrix while no positive results were obtained following transformation with the chit - 42 gene. In relation to the At NPR1 gene more than 30 independent transgenic lines have been obtained whose tolerance to R. necatrix is currently under evaluation. Concerning avocado transformation, more than 10 independent transgenic lines (derive d from an embryogenic line of an immature Duke7 zygotic embryo) have been obtained with At NPR1 gene. Plants have been recovered from one line and efforts are underway to recover plants from other lines following micrografting of the transgenic sprouted sho ots onto in vitro germinated seedlings.[ES] Uno de los factores limitantes de la producción de aguacate en España es la
enfermedad causada por el hongo R. necatrix. La manipulación genética podría ser de utilidad
para introducir caracteres de resistencia en este cultivo. Se ha establecido un sistema eficiente
de transformación en aguacate usando la cepa de Agrobacterium AGL1 y células
embriogénicas como diana, sin embargo, la conversión en plantas de los embriones
transgénicos necesita ser mejorada. Por esta razón, estamos utilizando la fresa, otro huésped
de R. necatrix, como especie modelo para testar el efecto de varios transgenes (2 de origen
fúngico, la quitinasa chit-42 y la β-1,3-glucanasa de Trichoderma harzianum, y uno derivado de
plantas, AtNPR1), en la inducción de tolerancia a este patógeno tras la transformación de esta
especie.
La transformación de fresa con el gen de β -1,3-glucanasa ha permitido la selección de
dos líneas, β6 y β10, con mayor tolerancia a R. necatrix, mientras que no se han obtenido
resultados positivos con el gen chit-42. En relación con el gen AtNPR1, se han obtenido más
de 30 líneas transgénicas independientes, cuya tolerancia frente a R. necatrix se está
evaluando en la actualidad.
En relación con la transformación de aguacate, más de 10 líneas transgénicas
independientes (derivadas de una línea embriogénica obtenida a partir de un embrión zigótico
inmaduro del cv. Duke 7) se han obtenido con el gen AtNPR1. Se han recuperado plantas de
una línea y actualmente se está intentando recuperar plantas de otras líneas mediante
microinjerto de los embriones transgénicos germinados.Este trabajo se ha realizado en el marco del proyecto AGL2008 - 05453 - C02 - 01/AGR.Peer Reviewe
Making Climate Change Mitigation and Adaptability Real in Africa with Conservation Agriculture
In this report, the authors have gathered essential information on how the agricultural sector can respond to climate change through Conservation Agriculture (CA). This document aims to serve as a basis for decision-making based on science and agricultural experimentation in Africa
Peculiarities of selecting the gearboxes and wheel shift coefficients in the optimization of drive gear transmissions
В якості вузлового моменту оптимізаційного проектування тягових зубчастих передач залізничного рухомого складу виділено процедуру обґрунтованого вибору коефіцієнтів зміщення шестерень і коліс за рахунок використання відповідних блокувальних контурів. Обґрунтовано актуальність досліджень з розроблення методичного забезпечення для раціонального отримання блокувальних контурів при проектуванні тягових зубастих передач. Представлені розроблені математичні залежності, що пов’язують фіксовані величині обмежувальних і контрольованих параметрів передач з числами зубців і коефіцієнтами зміщення шестерні та колеса. Їх використання дозволяє отримувати конкретні блокувальні контури для вибору коефіцієнтів зміщення шестерні та колеса при оптимізаційному проектуванні тягових зубчастих передач з різними початковими параметрами. Наведено приклад практичної реалізації розроблених математичних залежностей при отриманні блокувального контуру для вибору коефіцієнтів зміщення шестерні та колеса тягової зубчастої передачі сучасного магістрального вантажного тепловозу. Зроблено висновок про доцільність використання запропонованого методичного забезпечення при оптимізаційному проектуванні тягових зубчатих передач.As a key point in the optimization design of traction gears of the railway rolling stock, a procedure for a reasonable choice of the coefficients for the displacement of gears and wheels is provided by using the appropriate blocking circuits. The relevance of studies on the development of methodological support for the rational production of blocking contours in the design of traction-toothed gears is substantiated. The developed mathematical dependences connecting the fixed values of the limiting and controlled parameters of the gears with the numbers of the teeth and the gearing coefficients of the gears and wheels are presented. Their use makes it possible to obtain specific blocking contours for the selection of gear and wheel bias coefficients in the optimization design of traction gears with different initial parameters. An example of the practical implementation of the developed mathematical dependencies in obtaining a blocking contour for selecting the gear displacement coefficients and the traction gear wheel of a modern mainline freight locomotive is given. The conclusion is made about the expediency of using the proposed methodological support in the optimization design of traction gears
Dynamic Provisioning: Some Lessons from Existing Experiences
After analyzing the different reasons why the financial system and also the regulatory framework induced procyclicality, this paper reviews the experiences of three countries which have introduced dynamic provisioning as a regulatory tool to limit procyclicality. The case of Spain - the country with the longest experience - is reviewed, as well as those of Colombia and Peru - countries that have recently adopted dynamic provisioning. A number of policy lessons are drawn from that comparison
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