Interactions between Eriosyce villicumensis (Cactaceae) and shrubs: a study case in the hyper arid Monte desert of Argentina

Se estudió la distribución espacial intraespecífica e interespecífica de Eriosyce villicumensis (Rausch) Katt. en tres unidades fisiográficas y a microescala bajo los arbustos. Se analizó la influencia de los arbustos en la radiación fotosintéticamente activa y temperatura del suelo. La distribución intraespecífica de E. villicumensis resultó aleatoria. La distribución interespecífica estuvo asociada con Larrea cuneifolia y/o Zuccagnia punctata, observándose disminución de asociación desde el centro al borde de los arbustos, coincidiendo con los gradientes de luz y temperatura detectados bajo los arbustos. En ambientes desérticos, la interacción entre especies es una estrategia que permite la supervivencia de varias especies.The spatial intraspecific and interspecific distribution of Eriosyce villicumensis (Rausch) Katt. was studied in three physiographic units and at micro-scale under shrubs. The influence of shrubs on photosynthetically active radiation and on soil temperature was analyzed. The intraspecific distribution of E. villicumensis was random. The interspecific distribution was highly associated with Larrea cuneifolia and/or Zuccagnia punctata, observing decreasing association from the centre toward the edge of shrub canopies, coinciding with both the light and temperature gradients detected under those shrubs. In desert environments, the interaction between species is a strategy that allows survival of several plants.Fil: Almiron, Martin Guillermo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martinez Carretero, Eduardo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentin

Payout Choices by Retirees in Chile: What Are They and Why?

In 1981 Chile adopted its new multi-pillar system, which featured privately managed individual accounts. Starting in 1983 payouts from the accounts were permitted and detailed rules about payouts were put in place. The Chilean scheme therefore gives us an opportunity to examine how pensioners and pension providers react to individual account systems during the payout stage and how regulations shape these reactions. We use aggregate time series data obtained from the pension fund and insurance industry regulators, individual-level data on all annuitants in the system, and interviews with pension providers and regulators for this analysis. Retirees in Chile have a choice between early versus normal retirement from the system and between annuitization versus programmed withdrawals (PW); lump sum withdrawals are largely ruled out. These choices determine the time stream of benefits and the eventual financial burden that will be placed on the public treasury. Almost twothirds of all retirees have annuitized, but this proportion differs greatly between early and normal age retirees. Currently 60% of all retirees have chosen to retire early, many before age 55. (Early retirement means that they stop contributing and start withdrawing; it does not mean that they stop working). Most (85% of) early retirees have annuitized, while most (66% of) normal age retirees have taken PW. We present evidence that this disparate behavior is explained by incentives and constraints stemming from guarantees and regulations on pensioners and pension providers. These rules have lead workers with small accumulations to take PW at the normal age, with the minimum pension guarantee providing longevity and investment insurance. They lead workers with large accumulations to retire early, with annuities providing insurance. Regulations have given insurance companies selling annuities a competitive advantage in marketing to this group, and they do so aggressively. Early access to retirement saving through early retirement or front-loaded PW imposes a potential financial burden on the government because of the minimum pension guarantee, which has been rising in real value through time. As a result, the expected public share of the total pension payout grows with a cohort’s age and may exceed expectations as cohorts that retired under the new system grow very old. Annuitization mitigates (but does not completely eliminate) this cost to the public treasury. This analysis suggests that, with appropriate incentives, a high proportion of pensioners will purchase annuities in countries with individual account systems. But these countries need to coordinate early withdrawal conditions with minimum pensions and other safety nets, in order to avoid moral hazard problems and unexpected public liabilities.

Sidelined: Title IX Retaliation Cases and Women’s Leadership in College Athletics

This paper summarizes some of the initial research findings obtained in the SERMON project, funded by Wireless@KTH. The main focus of this paper is on video streaming transmission and the quantification of how much can be gained, in terms of user satisfaction and network resource utilization, by exploiting this semantic knowledge at network level. For this purpose, different QoE-centric RRM strategies are proposed and their performances evaluated in respect to a “classical” agnostic scheme, in a scenario where users have different QoE requirements for different content types and as a function of the device screen resolution during a live video streaming transmission.QC 20140519</p

Statement on September 11: On cynicism, indifference, and naivete

Panel: Reflections on a Global Year: The Worldview, Post 9/1

Practitioner Interview

Phone interview with Guillermo Martinez Baquero from Interra by David Watkins, Jr. Interview questions asked inquired about (i) practitioner’s professional background, (ii) practitioner’s personal experience with systems analysis techniques and software in their job, (iii) role, benefits, and challenges in using systems analysis concepts in the water resources engineering profession, and (iv) recommendations for improving education of environmental and water resources systems analysis in universities

Wireless security proportional to county development

This paper verify the hypothesis developed counties have a higher wireless security level than undeveloped counties , this is performed by doing a quantitative study to a group of 50 samples gathered from a war drive database. In further sections of the paper will be explained the importance of wireless security and how companies like RSA have performed studies to determinate the wireless security level of several major cities around the world. By following the binomial test and median comparison, the reader will understand why in this paper the hypothesis was rejected. All the results indicate that no relation existed between the two variables, but the human behavior can be affected by many factors not only economical. Plenty of variables exist to study human behavior, for further studies others variables like education level can be considered to performed a study

Fluidized bed plants for heat and power production in future energy systems

Fluidized bed (FB) plants are used for heat and power production in several energy systems around the world, with particular importance in systems using large shares of renewable solid fuel, e.g., biomass. These FB plants are traditionally operated for base-load electricity production or for heat production, and thus characterized by relatively small and slow load changes. In parallel, as the transition towards energy systems with net-zero emissions increases the share of variable renewable energy (VRE) sources, the need for implementing variation management strategies at various timescales arises – giving heat and power plants the possibility to adapt their operations to accommodate the inherent variability of VRE sources. Following this, FB technology is envisioned for a wide range of novel applications expected to play significant roles in the decarbonization of energy systems, such as thermochemical energy storage and carbon capture and storage. In this context, research efforts are needed to investigate the technical and economic features of FB plants in energy systems with high levels of VRE.The aim of this thesis is to elucidate the capabilities of FB plants for heat and power production in net-zero emissions energy systems. For this purpose, two main pathways are explored: i) transient operation as fuel-fed plants, and ii) the potential conversion into decarbonized plants, i.e., into VRE-fed layouts providing dispatchable outputs.For fuel-fed FB plants, a dynamic model of biomass-fired FB plants has been developed, considering the two types of FB boilers (BFB and CFB) and including validation against steady-state and transient operational data collected from two commercial plants. As a novelty of this work the model describes both the gas (in-furnace) and water-steam sides such that the interactions between the two can be assessed. The results of the simulations show that i) the characteristic times for the gas side are shorter in BFB furnaces than in CFBs, albeit these times are for both furnace types not longer than those for the water-steam side; ii) the computed timescales for the dynamics of FB plants fall well within those required for offering complementing services to the grid; and iii) the use of control and operational strategies for the water-steam side can confer capabilities superior to fuel-feeding control in terms of avoiding undesirable unburnt emissions and providing temporary overload operation. The retrofit of fuel-fed FB plants into poly-generation facilities cogenerating a combustible biogenic gas is also assessed, revealing that partial combustion of this gas can be used to provide faster inherent dynamics than the original configuration.For VRE-fed FB layouts, techno-economic process modeling has been carried out for large-scale deployment of solar- and electricity-charging processes based on three different chemical systems: i) carbonation/calcination (calcium); ii) thermally reduced redox (cobalt oxides); and iii) chemically reduced redox (iron oxides). One attractive aspect of these layouts is the possibility to build part of them by retrofitting current fuel-fed FB plants. While the technical assessment for solar applications indicates that cobalt-based layouts offer the highest levels of efficiency and dispatchability, calcium-based processes present better economics owing to the use of inexpensive calcium material. The results also show that electricity-charged layouts such as iron looping can play an important role in the system providing variation management strategies to the grid while avoiding costly H2 storage. Further, the economic performances of VRE-fed FB layouts are benefitted by the generation of additional services and products (e.g., carbon capture and on-demand production of H2), and by scenarios with high volatility of the electricity prices

Dynamics of large-scale fluidized bed combustion plants

Fluidized bed combustion (FBC) plants are widely used in energy systems across the world for the thermochemical conversion of solid fuels, and are especially suitable for low-rank fuels (a category to which renewable solid fuels belong). FBC plants are traditionally operated for base-load electricity production and for heat production, both of which processes are characterized by steady and stable operation. As the share of variable renewable electricity (VRE) sources is expected to increase dramatically, FBC plants will have to adapt their operations to the new flexibility requirements related to the inherent variability of VRE sources. By enhancing their operational and product flexibilities, FBC plants can remain financially attractive and offer services to support the balancing of the grid. As tools for assessing the operational flexibility of thermal power plants, dynamic modeling and simulation are gaining attention from both researchers and plant operators. However, it is a common practice to assume that the dynamics of the gas side are much faster than those of the water-steam side, i.e., not accounting for the in-furnace dynamic mechanisms.This thesis aims to characterize the dynamic behaviors of commercial-scale FBC plants, accounting for both the gas and water-steam sides of bubbling and circulating fluidized bed (BFB and CFB) units. For this purpose, a dynamic semiempirical model of the gas side of FBC plants is developed and integrated into a process model of the water-steam side. The models are validated against steady-state and transient operational data measured at two commercial-scale industrial units. The model is then used to analyze the inherent dynamics of the gas and water-steam sides, to compare the transient behaviors of BFB and CFB units, and to assess the dynamic performances of FBC plants when operated under different control structures. The results of the dynamic analysis show that the stabilization times of the temperatures across the furnace differ, largely based on the local heat capacity of the region in the furnace, i.e., the amount of bulk solids. The work includes an assessment of the impact of the characteristic times of the in-furnace mechanisms (i.e., fluid dynamics, fuel conversion and heat transfer) on the computed stabilization times of key in-furnace variables at plant level, and suggests some simple mathematical relationships for predicting these times. When accounting for the water-steam side, the results show that the inherent dynamics of variables such as live steam pressure, flow and power production are in the same order of magnitude as the dynamics of the gas side, particularly for the CFB case. This highlights the importance of accounting for the gas side when attempting to model accurately the dynamics of FBC plants. Furthermore, FBC plants are found to be able to provide fast load changes when operated under control structures that manipulate the live steam valve, although this is found to trigger operational issues, such as pressure overshoots.The results of this thesis are of particular importance in terms of assessing the transient capabilities of FBC plants to operate in electricity-driven markets where fast operation is required, and they can be used to identify opportunities and challenges. Furthermore, knowledge about the transient operation of large-scale FB reactors will be crucial for the development of FB applications other than combustion, such as polygeneration or thermochemical energy storage

Using semantics for automating the authentication of Web APIs

Recent technology developments in the area of services on the Web are marked by the proliferation of Web applications and APIs. The implementation and evolution of applications based on Web APIs is, however, hampered by the lack of automation that can be achieved with current technologies. Research on semantic Web services is there fore trying to adapt the principles and technologies that were devised for traditional Web services, to deal with this new kind of services. In this paper we show that currently more than 80% of the Web APIs require some form of authentication. Therefore authentication plays a major role for Web API invocation and should not be neglected in the context of mashups and composite data applications. We present a thorough analysis carried out over a body of publicly available APIs that determines the most commonly used authentication approaches. In the light of these results, we propose an ontology for the semantic annotation of Web API authentication information and demonstrate how it can be used to create semantic Web API descriptions. We evaluate the applicability of our approach by providing a prototypical implementation, which uses authentication annotations as the basis for automated service invocation