Interazioni piante - insetti: ruolo delle formiche in un sistema multitrofico. Aspetti ecoetologici ed applicativi

Le formiche svolgono un importante ruolo all’interno degli ecosistemi ed alcune specie sono considerate keystone in quanto in grado di modificare la componente biotica e/o abiotica dell’ecosistema stesso. Sono animali ubiquitari che hanno colonizzato molteplici ambienti, compresi gli agroecosistemi. Negli agroecosistemi spesso svolgono un ruolo impattante determinando la diffusione o il regresso di specie di artropodi, alcune delle quali dannose alle colture. La presente ricerca tiene conto di un’ampia visione dei rapporti ecoetologici intercorrenti tra le formiche e la componente biotica di un ecosistema, utilizzando il concetto di rete multitrofica. In quest’ottica, si è pensato di costruire un sistema multitrofico costituito da una specie vegetale di interesse agrario (Cucumis sativus), dai suoi fitofagi naturali, divisi in fitomizi (afidi) (Aphis gossypii e Myzus persicae) e fitofagi masticatori (bruchi del lepidottero Mamestra brassicae), formiche (Formica pratensis) e predatori afidofagi (Aphidolets aphidimyza). Il sistema multitrofico è stato utilizzato sia per studiare l’aggressività delle formiche, sia per verificare l’esistenza di una comunicazione interspecifica tra le formiche e le piante (allelochimici). Gli studi sull’aggressività sono consistiti nel: • Verificare il livello di aggressività delle formiche nei confronti di un fitofago masticatore, competitore degli afidi nello sfruttare la pianta ospite. • Verificare se la presenza di afidi mutualisti fa variare il livello di aggressività delle formiche verso il competitore. • Verificare se esiste aggressività verso un predatore di afidi, i quali, secondo il paradigma della trofobiosi, dovrebbero essere difesi dalle formiche in cambio della melata. • Verificare se il predatore ha evoluto strategie volte ad eludere il controllo delle formiche sugli insetti che si approcciano alla colonia di afidi. Gli studi sui rapporti piante-formiche sono stati effettuati mediante olfattometro, osservando la risposta delle formiche alle sostanze volatili provenienti da piante infestate in modo differente con i fitofagi del sistema. Attraverso il trappolaggio e l’analisi gas-cromatografica delle sostanze prodotte dalle piante oggetto di studio abbiamo quindi individuato tipo e quantità di ogni composto volatile. Oltre alle piante di cetriolo, per questi esperimenti sono state utilizzate anche piante di patata (Solanum tuberosum). Dagli esperimenti sull’aggressività è risultato che le formiche manifestano un elevato potenziale predatorio, eradicando completamente la presenza dei bruchi sulle piante. Questo livello di aggressività tuttavia non cresce con la presenza degli afidi mutualisti che dovrebbero essere difesi dai competitori. Le formiche inoltre non sono in grado di sopprimere i predatori afidofagi che ipotizziamo riescano ad effettuare un camuffamento chimico, assumendo gli odori degli afidi dei quali si nutrono. I risultati degli esperimenti in olfattometro mostrano una chiara risposta positiva delle formiche verso gli odori di alcune delle piante infestate. Vi sono delle differenze nella risposta in funzione della specie di fitofago presente e della specie di pianta utilizzata. Nei trattamenti in cui erano presenti le piante di C. sativus, gli esperimenti in olfattometro hanno mostrato che le formiche rispondono in modo significativo agli odori emessi dalle piante in cui vi era la presenza del fitofago masticatore M. brassicae, solo o in associazione con A. gossypii. La presenza dei soli afidi, sia mutualisti (A. gossypii) sia non mutualisti (M. persicae), non ha invece indotto una risposta significativa nelle formiche rispetto agli odori delle piante non infestate. Nei trattamenti in cui erano presenti le piante di S. tuberosum la scelta delle formiche è stata significativa verso gli odori emessi dalle piante infestate con ciascuna delle singole specie di erbivori rispetto alle piante non infestate. Gli esperimenti sull’analisi delle sostanze volatili emesse dalle piante hanno confermato che gli organismi vegetali sono una vera centrale di produzione biochimica, infatti ben 91 composti volatili diversi sono stati individuati dall’analisi gas-cromatografica delle piante di cetriolo e 85 in quelle di patata. Dalle elaborazioni effettuate, rispettivamente 27 e 4 di essi sono prodotti esclusivamente dalle piante attaccate dai fitofagi. In generale, il cambiamento più consistente è dato dalla quantità di alcune sostanze volatili emesse dalle piante infestate rispetto a quelle integre che determina un cambiamento nei rapporti tra le sostanze che compongono i volatiles. E’ probabile che l’effetto attrattivo esercitato sulle formiche sia dato da un Blend di sostanze più che dai singoli composti presenti

SAP-Related Education - Status-Quo and Experience

Integrating Enterprise Systems solutions in the curriculum of not only universities but all types of institutes of higher learning has been a major challenge for nearly ten years. Enterprise Systems education is surprisingly well documented in a number of papers on Information Systems education. However, most publications in this area report on the individual experiences of an institution or an academic. This paper focuses on the most popular Enterprise System - SAP - and summarizes the outcomes of a global survey on the status quo of SAP-related education. Based on feedback of 305 lecturers and more than 700 students, it reports on the main factors of Enterprise Systems education including, critical success factors, alternative hosting models, and students’ perceptions. The results show among others an overall increasing interest in advanced SAP solutions and international collaboration, and a high satisfaction with the concept of using Application Hosting Centers.

A meta-study of SAP financials in the Queensland Government

This thesis consists of three related studies: an ERP Major Issues Study; an Historical Study of the Queensland Government Financial Management System; and a Meta-Study that integrates these and other related studies conducted under the umbrella of the Cooperative ERP Lifecycle Knowledge Management research program. This research provides a comprehensive view of ERP lifecycle issues encountered in SAP R/3 projects across the Queensland Government. This study follows a preliminary ERP issues study (Chang, 2002) conducted in five Queensland Government agencies. The Major Issues Study aims to achieve the following: (1) identify / explicate major issues in relation to the ES life-cycle in the public sector; (2) rank the importance of these issues; and, (3) highlight areas of consensus and dissent among stakeholder groups. To provide a rich context for this study, this thesis includes an historical recount of the Queensland Government Financial Management System (QGFMS). This recount tells of its inception as a centralised system; the selection of SAP and subsequent decentralisation; and, its eventual recentralisation under the Shared Services Initiative and CorpTech. This historical recount gives an insight into the conditions that affected the selection and ongoing management and support of QGFMS. This research forms part of a program entitled Cooperative ERP Lifecycle Knowledge Management. This thesis provides a concluding report for this research program by summarising related studies conducted in the Queensland Government SAP context: Chan (2003); Vayo et al (2002); Ng (2003); Timbrell et al (2001); Timbrell et al (2002); Chang (2002); Putra (1998); and, Niehus et al (1998). A study of Oracle in the United Arab Emirates by Dhaheri (2002) is also included. The thesis then integrates the findings from these studies in an overarching Meta-Study. The Meta-Study discusses key themes across all of these studies, creating an holistic report for the research program. Themes discussed in the meta-study include common issues found across the related studies; knowledge dynamics of the ERP lifecycle; ERP maintenance and support; and, the relationship between the key players in the ERP lifecycle.

Optimization of long rural feeders using a genetic algorithm

This paper describes the optimization of conductor size and the voltage regulator location & magnitude of long rural distribution lines. The optimization minimizes the lifetime cost of the lines, including capital costs and losses while observing voltage drop and operational constraints using a Genetic Algorithm (GA). The GA optimization is applied to a real Single Wire Earth Return (SWER) network in regional Queensland and results are presented.

SAP webflow made configurable: unifying workflow templates into a configurable model

To facilitate the implementation of workflows, enterprise and workflow system vendors typically provide workflow templates for their software. Each of these templates depicts a variant of how the software supports a certain business process, allowing the user to save the effort of creating models and links to system components from scratch by selecting and activating the appropriate template. A combination of the strengths from different templates is however only achievable by manually adapting the templates which is cumbersome. We therefore suggest in this paper to combine different workflow templates into a single configurable workflow template. Using the workflow modeling language of SAP’s WebFlow engine, we show how such a configurable workflow modeling language can be created by identifying the configurable elements in the original language. Requirements imposed on configurations inhibit invalid configurations. Based on a default configuration such configurable templates can be used as easy as the traditional templates. The suggested approach is also applicable to other workflow modeling languages

Voltage unbalance improvement in low voltage residential feeders with rooftop PVs using custom power devices

Voltage unbalance is a major power quality problem in low voltage residential feeders due to the random location and rating of single-phase rooftop photovoltaic cells (PV). In this paper, two different improvement methods based on the application of series (DVR) and parallel (DSTATCOM) custom power devices are investigated to improve the voltage unbalance problem in these feeders. First, based on the load flow analysis carried out in MATLAB, the effectiveness of these two custom power devices is studied vis-à-vis the voltage unbalance reduction in urban and semi-urban/rural feeders containing rooftop PVs. Their effectiveness is studied from the installation location and rating points of view. Later, a Monte Carlo based stochastic analysis is carried out to investigate their efficacy for different uncertainties of load and PV rating and location in the network. After the numerical analyses, a converter topology and control algorithm is proposed for the DSTATCOM and DVR for balancing the network voltage at their point of common coupling. A state feedback control, based on pole-shift technique, is developed to regulate the voltage in the output of the DSTATCOM and DVR converters such that the voltage balancing is achieved in the network. The dynamic feasibility of voltage unbalance and profile improvement in LV feeders, by the proposed structure and control algorithm for the DSTATCOM and DVR, is verified through detailed PSCAD/EMTDC simulations.

Voltage unbalance reduction in low voltage feeders by dynamic switching of residential customers among three phases

Low voltage distribution feeders with large numbers of single phase residential loads experience severe current unbalance that often causes voltage unbalance problems. The addition of intermittent generation and new loads in the form of roof top photovoltaic generation and electric vehicles makes these problems even more acute. In this paper, an intelligent dynamic residential load transfer scheme is proposed. Residential loads can be transferred from one phase to another phase to minimize the voltage unbalance along the feeder. Each house is supplied through a static transfer switch with three-phase input and single-phase output connection. The main controller, installed at the transformer will observe the power consumption in each load and determine which house(s) should be transferred from one phase to another in order to keep the voltage unbalance in the feeder at a minimum. The efficacy of the proposed load transfer scheme is verified through MATLAB and PSCAD/EMTDC simulations.

Smart Inter-Phase Switching of Residential Loads in Low Voltage Distribution Feeders

In order to dynamically reduce voltage unbalance along a low voltage distribution feeder, a smart residential load transfer system is discussed. In this scheme, residential loads can be transferred from one phase to another to minimize the voltage unbalance along the feeder. Each house is supplied through a static transfer switch and a controller. The master controller, installed at the transformer, observes the power consumption in each house and will determine which house(s) should be transferred from an initially connected phase to another in order to keep the voltage unbalance minimum. The performance of the smart load transfer scheme is demonstrated by simulations.

IT-enabled sustainability transformation—the case of SAP

This teaching case describes how SAP, a leading global information technology (IT) solutions provider, embarked on a large-scale transformation program to implement a dual sustainability strategy of: (a) internally transforming the organization, and (b) addressing a business opportunity by developing IT solutions that enable their customers to become more sustainable. This case provides students with significant information about the development of SAP towards sustainability, including the company's underlying motivation, their approach to change and related challenges, and their use of IT to enable the transformation. The teaching case provides an opportunity to critically examine the benefits and risks of using IT in an effort to improve the sustainability of an organization, and to develop appropriate models for sustainable strategies and IT implementation efforts.

A fast track SAP R/3 implementation at Guilbert Niceday

This paper examines the approach of Guilbert, a European stationery company, which has chosen a fast track strategy towards implementation of enterprise resource planning.

Impact of PV units in LV feeders on distribution system reliability

Re-supplying loads on outage through cross-connect from adjacent feeders in a distribution system may cause voltage drop and hence require load shedding. However, the surplus PV generated in some of the LV feeders can prevent load shedding, and improve reliability. In order to measure these effects, this paper proposes the application of Direct Load Flow method[1] in reliability evaluation of distribution systems with PV units. As part of this study, seasonal impacts on load consumption together with surplus PV output power injection to higher voltage networks are also considered. New indices are proposed to measure yearly expected energy export, from LV to MV and from MV to higher voltage network.

Sap properties and alk(en)ylresorcinol concentrations in Australian-grown mangoes.

Physical and chemical properties of sap and sap concentrations of constitutive alk(en)ylresorcinols were determined in several varieties of mango grown in different locations in Queensland, Australia, over two consecutive cropping seasons. Sap weight from individual fruit, sap pH, percentage of non-aqueous sap and concentrations of constitutive alk(en)ylresorcinols (5-n-heptadecenylresorcinol and 5-n-pentadecylresorcinol) in sap varied significantly among the varieties. 'Calypso', 'Keitt', 'Kensington Pride' and 'Celebration' had the greatest proportion of non-aqueous sap, whereas 'Nam Doc Mai' had the least. The highest concentrations of 5-n-heptadecenylresorcinol were found in the sap of 'Kensington Pride', and the lowest in 'Honey Gold' and 'Nam Doc Mai'. Highest concentrations of 5-n-pentadecylresorcinol were found in sap of 'Calypso' and 'Celebration', and the lowest levels were in 'Honey Gold' and 'Nam Doc Mai'. There was a direct relationship between the percentage of non-aqueous sap and the concentrations of alk(en)ylresorcinols (r(2) = 0.77 for 5-n-heptadecenylresorcinol, and r(2) = 0.87 for 5-n-pentadecylresorcinol). The alk(en)ylresorcinols were distributed mainly in the upper non-aqueous phase of 'Kensington Pride' sap. Growing location also had significant effects on the composition of mango sap but the effects appeared to be related to differences in maturity. Sap removal is necessary to prevent sapburn, but considerable quantities of alk(en)ylresorcinols that assist in protecting the harvested fruit from anthracnose disease are also removed.