Dynamic resource management in SDN-based virtualized networks

Network virtualization allows for an abstraction between user and physical resources by letting a given physical infrastructure to be shared by multiple service providers. However, network virtualization presents some challenges, such as, efficient resource management, fast provisioning and scalability. By separating a network's control logic from the underlying routers and switches, software defined networking (SDN) promises an unprecedented simplification in network programmability, management and innovation by service providers, and hence, its control model presents itself as a candidate solution to the challenges in network virtualization. In this paper, we use the SDN control plane to efficiently manage resources in virtualized networks by dynamically adjusting the virtual network (VN) to substrate network (SN) mappings based on network status. We extend an SDN controller to monitor the resource utilisation of VNs, as well as the average loading of SN links and switches, and use this information to proactively add or remove flow rules from the switches. Simulations show that, compared with three state-of-art approaches, our proposal improves the VN acceptance ratio by about 40% and reduces VN resource costs by over 10%

Semantic validation of affinity constrained service function chain requests

Network Function Virtualization (NFV) has been proposed as a paradigm to increase the cost-efficiency, flexibility and innovation in network service provisioning. By leveraging IT virtualization techniques in combination with programmable networks, NFV is able to decouple network functionality from the physical devices on which they are deployed. This opens up new business opportunities for both Infrastructure Providers (InPs) as well as Service Providers (SPs), where the SP can request to deploy a chain of Virtual Network Functions (VNFs) on top of which its service can run. However, current NFV approaches lack the possibility for SPs to define location requirements and constraints on the mapping of virtual functions and paths onto physical hosts and links. Nevertheless, many scenarios can be envisioned in which the SP would like to attach placement constraints for efficiency, resilience, legislative, privacy and economic reasons. Therefore, we propose a set of affinity and anti-affinity constraints, which can be used by SPs to define such placement restrictions. This newfound ability to add constraints to Service Function Chain (SFC) requests also introduces an additional risk that SFCs with conflicting constraints are requested or automatically generated. Therefore, a framework is proposed that allows the InP to check the validity of a set of constraints and provide feedback to the SP. To achieve this, the SFC request and relevant information on the physical topology are modeled as an ontology of which the consistency can be checked using a semantic reasoner. Enabling semantic validation of SFC requests, eliminates inconsistent SFCs requests from being transferred to the embedding algorithm.Peer Reviewe

Parametric attosecond pulse amplification far from the ionization threshold from high order harmonic generation in He+^+

Parametric amplification of attosecond coherent pulses around 100 eV at the single-atom level is demonstrated for the first time by using the 3D time-dependent Schr{\"o}dinger equation in high-harmonic generation processes from excited states of He$^+$. We present the attosecond dynamics of the amplification process far from the ionization threshold and resolve the physics behind it. The amplification of a particular central photon energy requires the seed XUV pulses to be perfectly synchronized in time with the driving laser field for stimulated recombination to the He$^+$ ground state and is only produced in a few specific laser cycles in agreement with the experimental measurements. Our simulations show that the amplified photon energy region can be controlled by varying the peak intensity of the laser field. Our results pave the way to the realization of compact attosecond pulse intense XUV lasers with broad applications

Research into the information referents of deaf signers

The Information society is bringing about an increase in the number of information referents for deaf signers (those who use sign language). With the aim of exploring the ways most commonly used by deaf people to find out about current affairs, this paper summarizes some quantitative research that was carried out involving 138 deaf people: 69 in Spain and 69 in the US. The work is complemented qualitatively by a focus group in Gallaudet University, Washington, using American Sign Language (ASL), and by observations from three lecture/ news presentations which took place in Barcelona in Catalan Sign Language (LSC)

Desarrollo y validación estructural de una escala para evaluar la regulación de la ira y la tristeza en situaciones interpersonales

The purpose of this research was to develop and validate a new instrument to assess the regulation of anger and sadness in interpersonal situations, covering a wide range of emotion regulation strategies. Two studies were carried out, both of them using purposively selected samples. In Study 1 we created a set ofitems based on previous studies of emotion regulation, applied a preliminary version of this scale to a pilot sample of undergraduate students (n = 400), and then selected, using exploratory factor analysis (EFA), the best 28 items to include in a brief version of the instrument, the Scale of Emotion Regulation in Interpersonal Situations (SERIS). In Study 2 we tested the resulting scale ina new sample of undergraduate students (n = 259) by means of confirmatory factor analysis. Study 2 validated the factor structure identified in the EFA. Results showed that the scale has adequate internal consistency and psychometric properties. The new scale also identifies the strategies that are most frequently used in the anger and sadness scenarios, showing differential patterns which are consistent with previous literature on emotion regulation. We discuss the limitations of the study and acknowledge that future studies addressing the scale’s convergent and discriminant validity are now required.El objetivo de este trabajo es desarrollar una escala para evaluar la regulación emocional de la ira y la tristeza en situaciones interpersonales y que incluya un amplio rango de estrategias de regulación. Se realizaron dos estudios, contando ambos con muestras seleccionadas de manera intencional. En el estudio 1, se construyó un banco de ítems a partir de la revisión de la literatura, se aplicó a una muestra de estudiantes universitarios (n = 400) y se seleccionaron, mediante análisis factorial exploratorio, los mejores 28 indicadores para conformaruna escala breve llamada Escala de Regulación Emocional en Situaciones Interpersonales (ERESI). En el estudio 2 se validó en una nueva muestra, compuesta también por estudiantes universitarios (n = 259), la estructura factorial de la escala desarrollada en el estudio 1, aplicando un análisis factorial confirmatorio. Los resultados validaron la estructura factorial extraída del estudio 1, y señalaron que el instrumento cuenta con adecuada consistencia interna y validez estructural. También se verificó que el instrumento permite identificarlas estrategias más aplicadas en las situaciones de ira y de tristeza, hallando patrones diferenciales para cada emoción, y consistentes con la literatura existente sobre regulación emocional. Se discutieron las limitaciones y la necesidad de continuar con estudios de validación convergente y discriminante

A dynamic pricing algorithm for a network of virtual resources

A service chain is a combination of network services (e.g. network address translation (NAT), a firewall, etc.) that are interconnected to support an application (e.g. video-on-demand). Building a service chain requires a set of specialized hardware devices each of which need to be configured with their own command syntax. By moving management functions out of forwarding hardware into controller software, software-defined networking (SDN) simplifies provisioning and reconfiguration of service chains. By moving the network functions out of dedicated hardware devices into software running on standard x86 servers, network function virtualization (NFV) turns the deployment of a service chain into a more (cost)-efficient and flexible process. In an SDN/NFV-based architecture, those service chains are composed of virtual network functions (VNFs) that need to be mapped to physical network components. In literature, several algorithmic approaches exist to do so efficiently and cost-effectively. However, once mapped, a simple revenue model is used for pricing the requested substrate resources. This often leads to a loss of revenue for the infrastructure provider. In this paper, we propose a more advanced, dynamic pricing algorithm for pricing the requested substrate resources. The proposed algorithm increases the infrastructure provider's revenue based on historic data, current infrastructure utilization levels and the pricing of competitors. Our experimental evaluation shows that the proposed algorithm increases the revenue of the infrastructure provider significantly, independent of the average network utilization.Peer Reviewe

Spanish companies’ website communication of environmental, social, and governance information

This study’s goal is to analyze the website communication of environmental, social, and governance –Environmental Social Governance (ESG)– information by companies on the Madrid Stock Exchange. The empirical descriptive and inferential analysis determines IBEX35 companies’ regulatory compliance in disclosure of non-financial information through examination of their website disclosure of ESG information. Economic-financial information from the Iberian Balance Sheet Analysis System (Sistema de Análisis de Balances Ibéricos (SABI)) database was also used to investigate whether the firms that communicate this information better are also more economically efficient. The study results reveal that IBEX35 companies’ website disclosure provides heterogeneous information that is difficult to access and that they need to improve website transparency by communicating sound, sustainable non-financial reports. Further, a significant correlation was found between the companies that disclose the most ESG information and those that have the highest economic profitability –that is, those that are best adapted to the Spanish legal system and compatible with the challenges established by the UN’s Agenda 2030

Development and structural validation of a scale to assess regulation of anger and sadness in interpersonal situations

The purpose of this research was to develop and validate a new instrument to assess the regulation of anger and sadness in interpersonal situations, covering a wide range of emotion regulation strategies. Two studies were carried out, both of them using purposively selected samples. In Study 1 we created a set ofitems based on previous studies of emotion regulation, applied a preliminary version of this scale to a pilot sample of undergraduate students (n = 400), and then selected, using exploratory factor analysis (EFA), the best 28 items to include in a brief version of the instrument, the Scale of Emotion Regulation in Interpersonal Situations (SERIS). In Study 2 we tested the resulting scale ina new sample of undergraduate students (n = 259) by means of confirmatory factor analysis. Study 2 validated the factor structure identified in the EFA. Results showed that the scale has adequate internal consistency and psychometric properties. The new scale also identifies the strategies that are most frequently used in the anger and sadness scenarios, showing differential patterns which are consistent with previous literature on emotion regulation. We discuss the limitations of the study and acknowledge that future studies addressing the scale's convergent and discriminant validity are now required