Jorge Vallejo | Universiteit Gent and Vrije Universiteit Brussel (original) (raw)

Papers by Jorge Vallejo

Journal of Ethnopharmacology, 2009

Ethnopharmacological relevance: Atractylis gummifera L. and Centaurea ornata Willd. are locally m... more Ethnopharmacological relevance: Atractylis gummifera L. and Centaurea ornata Willd. are locally marketed herbal remedies, even though in Spain it is forbidden to sell toxic plants like Atractylis gummifera. Intoxications in Spain are mainly due to accidental substitution of Centaurea ornata with Atractylis gummifera which may be fatal. Aim of study: The aim of this article is to analyse the current use and marketing of Atractylis gummifera and Centaurea ornata in Badajoz and analyse the ethnopharmacological relevance of two recent cases of Atractylis gummifera poisoning. Background and methods: An ethnopharmacological survey was conducted in the area where one of the poisoned patients lives and in Guadiana del Caudillo. The use, knowledge and naming of the species involved in the poisoning was assessed. This information was complemented with an exhaustive search in Spanish ethnobotanical works on the ethnopharmacological uses of both species. Results: Intoxications are due to species' substitutions. The two species are similar in name and use in the area, and both are locally marketed. AG is mainly used to heal wounds and calcaneal spurs, and CO to treat gastric ulcers and wounds. Conclusions: New intoxications are likely since consumers often have limited knowledge of the plants they consume. Also, it is common to think that all medicinal plants are harmless. As the use of Atractylis gummifera seems to increase in the area, preventive measures need to be taken.

... Elisa Gonzalez Boix, Jorge Vallejos, Tom Van Cutsem *, Jessie Dedecker, and Wolfgang De Meute... more ... Elisa Gonzalez Boix, Jorge Vallejos, Tom Van Cutsem *, Jessie Dedecker, and Wolfgang De Meuter ... The first variant is a renew-on-call leased reference that automatically prolongs the lease upon each method call received by the remote object. ...

Journal of Business Ethics, 2009

Since it implies a reduction in the quality and the quantity of the natural resources, environmen... more Since it implies a reduction in the quality and the quantity of the natural resources, environmental degradation is a present day problem that requires immediate solutions. This situation is driving firms to undertake an environmental transformation process with the purpose of reducing the negative externalities that come from their economic activities. Within this context, environmental marketing is an emerging business philosophy by which organizations can address sustainability issues. Moreover, environmental marketing and orientation are seen as valuable strategies to improve a firm’s competitiveness. However, the literature that has analyzed the link between environmental strategies and firms’ results has been inconclusive and contradictory. In this study, we propose and test a model that analyses how the implementation of ecological issues within a firm’s marketing strategy and orientation influences organizational results. Data were obtained through a survey sent to Spanish manufacturing firms. The results show that environmental marketing positively affects firms’ operational and commercial performance and this improvement will influence their economic results. Moreover, environmental marketing is revealed as an excellent strategy to obtain competitive advantages in costs and in product differentiation. Thus, this study agrees with the researchers who affirm that environmental strategies positively affect firm’s competitiveness while reducing environmental impact.

Business Strategy and The Environment, 2008

In recent years, the protection of the environment has gained a growing importance. Accordingly, ... more In recent years, the protection of the environment has gained a growing importance. Accordingly, small and large firms have become aware of their responsibility and begun to develop environmental strategies as an enterprising challenge. In such a situation, this study describes firms' environmental orientation and its impact on the design of corporate and marketing strategies in the Spanish consumer product sector. The purpose of this paper is to identify different groups of firms according to their environmental behaviour.The information was obtained through 81 personal interviews with firms in the final consumer product sector. With the data obtained we have conducted several exploratory and confirmatory factor analyses and a cluster analysis. Findings have proved that there is a specific firm type characterized by certain variables: influence of external forces; environmental orientation; corporative and marketing strategies; size; macro-sector and, if existing, the environment department. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.

Tourism Review, 2010

Purpose – This study aims to identify typologies of women who take holiday decisions within the c... more Purpose – This study aims to identify typologies of women who take holiday decisions within the couple, characterizing their profile through their lifestyles and some socio-demographic variables. Design/methodology/approach – The information was obtained through a survey addressed to Spanish women who were married or lived with their partner. Data were used to perform two types of analyses: scales validation and

Many Ambient Intelligence (AmI) scenarios fit perfectly for auto-generated distributed networks, ... more Many Ambient Intelligence (AmI) scenarios fit perfectly for auto-generated distributed networks, but they assume the existence of good enough network topology organizing the connected devices. AmI scenarios need to handle an unanticipated number of participants and inappropriate distributed network topologies can affect the network's efficiency by making it unstable and hard to manage. This paper introduces PALTA, a self-adapting hybrid topology capable of dynamically adjusting its configuration by using a combination of existing topologies. PALTA allows the incremental construction of self-maintained distributed networks which take advantage of the current network state.

Context-aware systems are software systems which adapt their behaviour according to the context o... more Context-aware systems are software systems which adapt their behaviour according to the context of use. The requirements engineering phase is recognized as a primordial step to develop robust implementations of context-aware systems since it establishes a comprehensive understanding of the problem space. This paper proposes the Context-Oriented Domain Analysis (CODA) model which is a specialized approach for analyzing, structuring, and formalizing the software requirements of context-aware systems.

Predicate dispatching is a generalized form of dynamic dispatch, which has strong limitations whe... more Predicate dispatching is a generalized form of dynamic dispatch, which has strong limitations when arbitrary predicates of the underlying base language are used. Unlike classes, which enforce subset relationships between their sets of instances, arbitrary predicates generally do not designate subsets of each other, so methods whose applicability is based on predicates cannot be ordered according to their specificity in the general case. This paper introduces a decidable but expressive alternative mechanism called filtered dispatch that adds a simple preprocessing step before the actual method dispatch is performed and thus enables the use of arbitrary predicates for selecting and applying methods.

The omnipresent integration of computer technology in everyday applications introduces new opport... more The omnipresent integration of computer technology in everyday applications introduces new opportunities to make software systems aware of the context in which they are used. Such context-aware systems can respond more adequately to user expectations. However, modelling the context influence inside of software systems burdens developers for several reasons. First, context-dependent behaviour might crosscut the application logic of a software system. Next, since software systems can simultaneously reside in multiple contexts, context-dependent behaviour should be composable. Furthermore, since context information is volatile, these compositions are subject to change at runtime. This paper explores how layered design approaches can be used to deal with these specific characteristics.

This paper presents predicated generic functions, a novel programming language abstraction that a... more This paper presents predicated generic functions, a novel programming language abstraction that allows the expression of context-dependent behaviour in a declarative and modular manner, providing fine-grained control of method applicability and method specificity. Methods are guarded by predicates with user-defined orderings, thereby increasing the expressiveness of existing method dispatching approaches. We have prototyped our proposal in Lambic, an extension of the standard Common Lisp Object System. We illustrate and motivate our approach by discussing the implementation of a collaborative graphical editor.

In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network part... more In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network partitions due to the intermittent connectivity of mobile devices. Some of these failures will be permanent and require application-level failure handling. However, it is impossible to distinguish a permanent from a transient failure. Leasing provides a solution to this problem based on the temporal restriction of resources. But to date no leasing model has been designed specifically for MANETs. In this paper, we identify three characteristics required for a leasing model to be usable in a MANET, discuss the issues with existing leasing models and then propose the leased object references model, which integrates leasing with remote object references. In addition, we describe an implementation of the model in the programming language AmbientTalk. Leased object references provide an extensible framework that allows programmers to express their own leasing patterns and enables both lease holders (clients) and lease grantors (services) to deal with permanent failures.

Journal of Object Technology, 2007

Mobile networks composed of devices interconnected by wireless communication media frequently suf... more Mobile networks composed of devices interconnected by wireless communication media frequently suffer from partitions. If mobile devices depend on software services running on remote devices, such partitions may render the software services unavailable. We propose the use of code mobility to mitigate the unavailability of software services in mobile networks. We discuss the issues of existing mobility mechanisms, identify four characteristics necessary to support code mobility in mobile networks, and propose a model for code mobility, the Message-Oriented Mobility (MOM) model, that features such characteristics.

In order to tackle the problem of climate change we crucially need to develop a sustainable socie... more In order to tackle the problem of climate change we crucially need to develop a sustainable society. This requires everyone to become aware of the precariousness of the situation, while at the same time a major scientific effort is needed. A core issue standing in the way of sustainability is that of environmental pollution. People-centric sensing is an increasingly popular approach for monitoring pollution in urban environments . This model relies on mobile computing devices to enable ordinary citizens to assess their exposure to pollution factors in their everyday activities. A such, this sensing approach yields individualised data with a higher spatio-temporal granularity than systems based on sparse and stationary sensors , while the active involvement of citizens in the monitoring increases their awareness of environmental issues. However, people-centric sensing is hampered by the still limited capacities of current mobile devices, in terms of processing power and battery autonomy as well as the absence of specialised environmental sensors [3], limiting participation to those who have access to expensive or adapted devices.

Abstract—Context-enabled applications adapt their behaviour according to the context of use. We o... more Abstract—Context-enabled applications adapt their behaviour according to the context of use. We observe that this kind of applications imply a severe increase of runtime variability. To this end, we propose our Puzzle Approach, a conceptual framework specifically tailored ...

Implementing context-dependent behaviour of pervasive computing applications puts a great burden ... more Implementing context-dependent behaviour of pervasive computing applications puts a great burden on programmers: Devices need to continuously adapt not only to their own context, but also to the context of other devices they interact with. We present an approach that modularises behavioural adaptations into roles. Role selection takes the context of all the devices involved in an interaction into account, ensures an unambiguous scope of adaptation even in the presence of concurrency, and protects the privacy of the devices. Thus, our context-dependent role (CDR) model facilitates expressing interactions between applications in different, possibly conflicting contexts.

A growing trend in software construction advocates the encapsulation of software building blocks ... more A growing trend in software construction advocates the encapsulation of software building blocks as features which better match the specification of requirements. As a result, programmers find it easier to design and compose different variations of their systems. Feature-oriented programming (FOP) is the research domain that targets this trend. We argue that the state-of-the-art techniques for FOP have shortcomings because they specify a feature as a set of building blocks rather than a transition that has to be applied on a software system in order to add that feature's functionality to the system.

In aspect-oriented programming, pointcuts are formulated as conditions over the context of dynami... more In aspect-oriented programming, pointcuts are formulated as conditions over the context of dynamic events in the execution of a program. Hybrid pointcut languages also allow this context to come from interactions between the pointcut language and the base program. While some pointcut languages only allow conditions on the current execution event, more recent proposals have demonstrated the need for expressing conditions over a history of join points. Such pointcut languages require means to balance the expressiveness of the language with the additional memory and runtime overhead caused by keeping a history of join point context data. In this paper, we introduce a logic-based pointcut language that allows interaction with the base program as well as pointcuts over a history of join points. We introduce forward chaining as an implementation model for this language, and discuss possible optimization strategies for the additional overhead. 1 1 ACM, 2007. This is a minor revision of the work published in

Journal of Ethnopharmacology, 2009

Ethnopharmacological relevance: Atractylis gummifera L. and Centaurea ornata Willd. are locally m... more Ethnopharmacological relevance: Atractylis gummifera L. and Centaurea ornata Willd. are locally marketed herbal remedies, even though in Spain it is forbidden to sell toxic plants like Atractylis gummifera. Intoxications in Spain are mainly due to accidental substitution of Centaurea ornata with Atractylis gummifera which may be fatal. Aim of study: The aim of this article is to analyse the current use and marketing of Atractylis gummifera and Centaurea ornata in Badajoz and analyse the ethnopharmacological relevance of two recent cases of Atractylis gummifera poisoning. Background and methods: An ethnopharmacological survey was conducted in the area where one of the poisoned patients lives and in Guadiana del Caudillo. The use, knowledge and naming of the species involved in the poisoning was assessed. This information was complemented with an exhaustive search in Spanish ethnobotanical works on the ethnopharmacological uses of both species. Results: Intoxications are due to species' substitutions. The two species are similar in name and use in the area, and both are locally marketed. AG is mainly used to heal wounds and calcaneal spurs, and CO to treat gastric ulcers and wounds. Conclusions: New intoxications are likely since consumers often have limited knowledge of the plants they consume. Also, it is common to think that all medicinal plants are harmless. As the use of Atractylis gummifera seems to increase in the area, preventive measures need to be taken.

... Elisa Gonzalez Boix, Jorge Vallejos, Tom Van Cutsem *, Jessie Dedecker, and Wolfgang De Meute... more ... Elisa Gonzalez Boix, Jorge Vallejos, Tom Van Cutsem *, Jessie Dedecker, and Wolfgang De Meuter ... The first variant is a renew-on-call leased reference that automatically prolongs the lease upon each method call received by the remote object. ...

Journal of Business Ethics, 2009

Since it implies a reduction in the quality and the quantity of the natural resources, environmen... more Since it implies a reduction in the quality and the quantity of the natural resources, environmental degradation is a present day problem that requires immediate solutions. This situation is driving firms to undertake an environmental transformation process with the purpose of reducing the negative externalities that come from their economic activities. Within this context, environmental marketing is an emerging business philosophy by which organizations can address sustainability issues. Moreover, environmental marketing and orientation are seen as valuable strategies to improve a firm’s competitiveness. However, the literature that has analyzed the link between environmental strategies and firms’ results has been inconclusive and contradictory. In this study, we propose and test a model that analyses how the implementation of ecological issues within a firm’s marketing strategy and orientation influences organizational results. Data were obtained through a survey sent to Spanish manufacturing firms. The results show that environmental marketing positively affects firms’ operational and commercial performance and this improvement will influence their economic results. Moreover, environmental marketing is revealed as an excellent strategy to obtain competitive advantages in costs and in product differentiation. Thus, this study agrees with the researchers who affirm that environmental strategies positively affect firm’s competitiveness while reducing environmental impact.

Business Strategy and The Environment, 2008

In recent years, the protection of the environment has gained a growing importance. Accordingly, ... more In recent years, the protection of the environment has gained a growing importance. Accordingly, small and large firms have become aware of their responsibility and begun to develop environmental strategies as an enterprising challenge. In such a situation, this study describes firms' environmental orientation and its impact on the design of corporate and marketing strategies in the Spanish consumer product sector. The purpose of this paper is to identify different groups of firms according to their environmental behaviour.The information was obtained through 81 personal interviews with firms in the final consumer product sector. With the data obtained we have conducted several exploratory and confirmatory factor analyses and a cluster analysis. Findings have proved that there is a specific firm type characterized by certain variables: influence of external forces; environmental orientation; corporative and marketing strategies; size; macro-sector and, if existing, the environment department. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.

Tourism Review, 2010

Purpose – This study aims to identify typologies of women who take holiday decisions within the c... more Purpose – This study aims to identify typologies of women who take holiday decisions within the couple, characterizing their profile through their lifestyles and some socio-demographic variables. Design/methodology/approach – The information was obtained through a survey addressed to Spanish women who were married or lived with their partner. Data were used to perform two types of analyses: scales validation and

Many Ambient Intelligence (AmI) scenarios fit perfectly for auto-generated distributed networks, ... more Many Ambient Intelligence (AmI) scenarios fit perfectly for auto-generated distributed networks, but they assume the existence of good enough network topology organizing the connected devices. AmI scenarios need to handle an unanticipated number of participants and inappropriate distributed network topologies can affect the network's efficiency by making it unstable and hard to manage. This paper introduces PALTA, a self-adapting hybrid topology capable of dynamically adjusting its configuration by using a combination of existing topologies. PALTA allows the incremental construction of self-maintained distributed networks which take advantage of the current network state.

Context-aware systems are software systems which adapt their behaviour according to the context o... more Context-aware systems are software systems which adapt their behaviour according to the context of use. The requirements engineering phase is recognized as a primordial step to develop robust implementations of context-aware systems since it establishes a comprehensive understanding of the problem space. This paper proposes the Context-Oriented Domain Analysis (CODA) model which is a specialized approach for analyzing, structuring, and formalizing the software requirements of context-aware systems.

Predicate dispatching is a generalized form of dynamic dispatch, which has strong limitations whe... more Predicate dispatching is a generalized form of dynamic dispatch, which has strong limitations when arbitrary predicates of the underlying base language are used. Unlike classes, which enforce subset relationships between their sets of instances, arbitrary predicates generally do not designate subsets of each other, so methods whose applicability is based on predicates cannot be ordered according to their specificity in the general case. This paper introduces a decidable but expressive alternative mechanism called filtered dispatch that adds a simple preprocessing step before the actual method dispatch is performed and thus enables the use of arbitrary predicates for selecting and applying methods.

The omnipresent integration of computer technology in everyday applications introduces new opport... more The omnipresent integration of computer technology in everyday applications introduces new opportunities to make software systems aware of the context in which they are used. Such context-aware systems can respond more adequately to user expectations. However, modelling the context influence inside of software systems burdens developers for several reasons. First, context-dependent behaviour might crosscut the application logic of a software system. Next, since software systems can simultaneously reside in multiple contexts, context-dependent behaviour should be composable. Furthermore, since context information is volatile, these compositions are subject to change at runtime. This paper explores how layered design approaches can be used to deal with these specific characteristics.

This paper presents predicated generic functions, a novel programming language abstraction that a... more This paper presents predicated generic functions, a novel programming language abstraction that allows the expression of context-dependent behaviour in a declarative and modular manner, providing fine-grained control of method applicability and method specificity. Methods are guarded by predicates with user-defined orderings, thereby increasing the expressiveness of existing method dispatching approaches. We have prototyped our proposal in Lambic, an extension of the standard Common Lisp Object System. We illustrate and motivate our approach by discussing the implementation of a collaborative graphical editor.

In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network part... more In mobile ad hoc networks (MANETs) many partial failures are the result of temporary network partitions due to the intermittent connectivity of mobile devices. Some of these failures will be permanent and require application-level failure handling. However, it is impossible to distinguish a permanent from a transient failure. Leasing provides a solution to this problem based on the temporal restriction of resources. But to date no leasing model has been designed specifically for MANETs. In this paper, we identify three characteristics required for a leasing model to be usable in a MANET, discuss the issues with existing leasing models and then propose the leased object references model, which integrates leasing with remote object references. In addition, we describe an implementation of the model in the programming language AmbientTalk. Leased object references provide an extensible framework that allows programmers to express their own leasing patterns and enables both lease holders (clients) and lease grantors (services) to deal with permanent failures.

Journal of Object Technology, 2007

Mobile networks composed of devices interconnected by wireless communication media frequently suf... more Mobile networks composed of devices interconnected by wireless communication media frequently suffer from partitions. If mobile devices depend on software services running on remote devices, such partitions may render the software services unavailable. We propose the use of code mobility to mitigate the unavailability of software services in mobile networks. We discuss the issues of existing mobility mechanisms, identify four characteristics necessary to support code mobility in mobile networks, and propose a model for code mobility, the Message-Oriented Mobility (MOM) model, that features such characteristics.

In order to tackle the problem of climate change we crucially need to develop a sustainable socie... more In order to tackle the problem of climate change we crucially need to develop a sustainable society. This requires everyone to become aware of the precariousness of the situation, while at the same time a major scientific effort is needed. A core issue standing in the way of sustainability is that of environmental pollution. People-centric sensing is an increasingly popular approach for monitoring pollution in urban environments . This model relies on mobile computing devices to enable ordinary citizens to assess their exposure to pollution factors in their everyday activities. A such, this sensing approach yields individualised data with a higher spatio-temporal granularity than systems based on sparse and stationary sensors , while the active involvement of citizens in the monitoring increases their awareness of environmental issues. However, people-centric sensing is hampered by the still limited capacities of current mobile devices, in terms of processing power and battery autonomy as well as the absence of specialised environmental sensors [3], limiting participation to those who have access to expensive or adapted devices.

Abstract—Context-enabled applications adapt their behaviour according to the context of use. We o... more Abstract—Context-enabled applications adapt their behaviour according to the context of use. We observe that this kind of applications imply a severe increase of runtime variability. To this end, we propose our Puzzle Approach, a conceptual framework specifically tailored ...

Implementing context-dependent behaviour of pervasive computing applications puts a great burden ... more Implementing context-dependent behaviour of pervasive computing applications puts a great burden on programmers: Devices need to continuously adapt not only to their own context, but also to the context of other devices they interact with. We present an approach that modularises behavioural adaptations into roles. Role selection takes the context of all the devices involved in an interaction into account, ensures an unambiguous scope of adaptation even in the presence of concurrency, and protects the privacy of the devices. Thus, our context-dependent role (CDR) model facilitates expressing interactions between applications in different, possibly conflicting contexts.

A growing trend in software construction advocates the encapsulation of software building blocks ... more A growing trend in software construction advocates the encapsulation of software building blocks as features which better match the specification of requirements. As a result, programmers find it easier to design and compose different variations of their systems. Feature-oriented programming (FOP) is the research domain that targets this trend. We argue that the state-of-the-art techniques for FOP have shortcomings because they specify a feature as a set of building blocks rather than a transition that has to be applied on a software system in order to add that feature's functionality to the system.

In aspect-oriented programming, pointcuts are formulated as conditions over the context of dynami... more In aspect-oriented programming, pointcuts are formulated as conditions over the context of dynamic events in the execution of a program. Hybrid pointcut languages also allow this context to come from interactions between the pointcut language and the base program. While some pointcut languages only allow conditions on the current execution event, more recent proposals have demonstrated the need for expressing conditions over a history of join points. Such pointcut languages require means to balance the expressiveness of the language with the additional memory and runtime overhead caused by keeping a history of join point context data. In this paper, we introduce a logic-based pointcut language that allows interaction with the base program as well as pointcuts over a history of join points. We introduce forward chaining as an implementation model for this language, and discuss possible optimization strategies for the additional overhead. 1 1 ACM, 2007. This is a minor revision of the work published in