Hierarchy and Competition in CSCW applications: Model and case study

CSCW applications need to adapt themselves to the functional and organizational structures of people that use them. However they do not usually support division in groups with a certain hierarchical structure among them. In this paper, we propose and study a theoretical model of groupware appliations that reflects those hierarchical interactions. The proposed model is also intended to evaluate the effects in performance derived from competitive and collaborative relationships among the components of a hierarchy of groups. In order to demonstrate the above ideas, a groupware game, called Alymod, was designed and implemented using a modified version of a well-known CSCW Toolkit, namely Groupkit. Groupkit was modified in order to support group interactions in the same CSCW application. In Alymod, participants compete or collaborate within a hierarchical structure to achieve a common goal (completing gaps in a text, finishing numerical series, resolving University course examinations, etc.).Publicad

On the efficiency of a dedicated LMA for multicast traffic distribution in PMIPv6 domains

IP multicast allows the efficient support of group communication services by reducing the number of IP flows needed for such communication. The increasing generalization in the use of multicast has also triggered the need for supporting IP multicast in mobile environments. Proxy Mobile IPv6 (PMIPv6) is a network-based mobility management solution, where the functionality to support the terminal movement resides in the network. Recently, a baseline solution has been adopted for multicast support in PMIPv6. Such base solution has inefficiencies in multicast routing because it may require multiple copies of a single stream to be received by the same access gateway. Nevertheless, there is an alternative solution to support multicast in PMIPv6 that avoids this issue. This paper evaluates by simulation the scalability of both solutions under realistic conditions, and provides an analysis of the sensitivity of the two proposals against a number of parameters

Geographic Patterns of Inversion Polymorphism in the Second Chromosome of the Cactophilic Drosophila buzzatii from Northeastern Argentina

The inversion polymorphisms of the cactophilic Drosophila buzzatti Patterson and Wheeler (Diptera: Drosophilidae) were studied in new areas of its distribution in Argentina. A total of thirty-eight natural populations, including 29 from previous studies, were analyzed using multiple regression analyses. The results showed that about 23% of total variation was accounted for by a multiple regression model in which only altitude contributed significantly to population variation, despite the fact that latitude and longitude were also included in the model. Also, inversion frequencies exhibited significant associations with mean annual temperature, precipitation, and atmospheric pressure. In addition, expected heterozygosity exhibited a negative association with temperature and precipitation and a positive association with atmospheric pressure. The close similarity of the patterns detected in this larger dataset to previous reports is an indication of the stability of the clines. Also, the concurrence of the clines detected in Argentina with those reported for colonizing populations of Australia suggests the involvement of natural selection as the main mechanism shaping inversion frequencies in D. buzzatii

Evolution of male genitalia: environmental and genetic factors affect genital morphology in two Drosophila sibling species and their hybrids

<p>Abstract</p> <p>Background</p> <p>The rapid evolution of genital morphology is a fascinating feature that accompanies many speciation events. However, the underlying patterns and explanatory processes remain to be settled. In this work we investigate the patterns of intraspecific variation and interspecific divergence in male genitalic morphology (size and shape) in the cactophilic sibling species <it>Drosophila buzzatii </it>and <it>D. koepferae</it>. Genital morphology in interspecific hybrids was examined and compared to the corresponding parental lines.</p> <p>Results</p> <p>Despite of being siblings, <it>D. buzzatii </it>and <it>D. koepferae </it>showed contrasting patterns of genital morphological variation. Though genitalic size and shape variation have a significant genetic component in both species, shape varied across host cacti only in <it>D. buzzatii</it>. Such plastic expression of genital shape is the first evidence of the effect of rearing substrate on genitalic morphology in <it>Drosophila</it>. Hybrid genital morphology was not intermediate between parental species and the morphological resemblance to parental strains was cross-dependent.</p> <p>Conclusion</p> <p>Our results suggest the evolution of different developmental networks after interspecific divergence and the existence of a complex genetic architecture, involving genetic factors with major effects affecting genital morphology.</p

Network-based localized IP mobility management: Proxy Mobile IPv6 and current trends in standardization

IP mobility support has been a hot topic over the last years, recently fostered by the role of IP in the evolution of the 3G mobile communication networks. Standardization bodies, namely IETF, IEEE and 3GPP are working on different aspects of the mobility aiming at improving the mobility experience perceived by users. Traditional IP mobility support mechanisms, Mobile IPv4 or Mobile IPv6, are based on the operation of the terminal to keep ongoing sessions despite the movement. The current trend is towards network-based solutions where mobility support is based on network operation. Proxy Mobile IPv6 is a promising specification that allows network operators to provide localized mobility support without relying on mobility functionality or configuration present in the mobile nodes, which greatly eases the deployment of the solution. This paper presents Proxy Mobile IPv6 and the different extensions that are been considered by the standardization bodies to enhance the basic protocol with interesting features needed to offer a richer mobility experience, namely, flow mobility, multicast and network mobility support.European Community's Seventh Framework ProgramThe research leading to the results presented in this paper has received funding from the Spanish MICINN through the I-MOVING project (TEC2010-18907) and from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement 258053 (MEDIEVAL project).Publicad

Stress compensation by gap monolayers for stacked InAs/GaAs quantum dots solar cells

In this work we report the stacking of 10 and 50 InAs quantum dots layers using 2 monolayers of GaP for stress compensation and a stack period of 18 nm on GaAs (001) substrates. Very good structural and optical quality is found in both samples. Vertical alignment of the dots is observed by transmission electron microscopy suggesting the existence of residual stress around them. Photocurrent measurements show light absorption up to 1.2 μm in the nanostructures together with a reduction in the blue response of the device. As a result of the phosphorus incorporation in the barriers, a very high thermal activation energy (431 meV) has also been obtained for the quantum dot emission

Characterization of CTX-M-14 and CTX-M-15 producing Escherichia coli strains causing neonatal sepsis

Neonatal sepsis is a disease affecting newborns ≤1 month of age with clinical symptoms and positive blood cultures. The number of Escherichia coli strains causing neonatal sepsis resistant to the antibiotics used in the treatment is increasing. In this study, two E. coli strains causing sepsis in neonates of mothers infected with an E. coli strain harboring extended spectrum beta-lactamases were characterized. The blaCTX-M-15 and the blaCTX-M-14 genes were found in an IncFIA and nontypeable transferable plasmids, respectively. In addition, these highly virulent strains belonged to ST705 and ST156 clonal groups, respectively. The presence of strains, which are highly virulent and resistant to ampicillin, gentamicin, and cephalosporins, makes a change in empirical treatment necessary as well as an increase in the surveillance of these infections

Inter-calibration trials between the R/V Cornide de Saavedra and the R/V Miguel Oliver in bottom trawl surveys off the Spanish coast

Bottom trawl surveys are conducted by the Spanish Oceanographic Institute (IEO) to provide information independent from the fisheries of commercial stocks: DEMERSALES in the northern Spanish Shelf, ARSA in the Gulf of Cadiz and MEDITS in the Mediterranean Shelf since 1983, 1993 and 1994, respectively. Surveys have been performed annually on board the R/V Cornide de Saavedra until 2013. This vessel (67 m, 1133 GRT) was built in 1972 and nowadays has been replaced by the new R/V Miguel Oliver (70 m, 2495 GRT). To guarantee the continuity between the two vessels of the abundance and biomass indices of the main target species and their length distributions, inter-calibration experiments have been performed for each of the three bottom trawl surveys. The goal of the inter-calibration between both vessels was to establish the most similar fishing conditions to detect and isolate if there was a vessel effect that caused different results in catches. And in if those differences were significant, to estimate calibration coefficients to homogenize abundance and biomass indices of the new vessel R/V Miguel Oliver with respect to the time series built with the old R/V Cornide de Saavedra. The inter-calibration experiment consisted in performing parallel tows with both vessels, using the same gear, and carrying out hauls of the same duration and speed. The parallel surveys in the V/R Cornide de Saavedra and the R/V Miguel Oliver followed the surveys protocols of IBTS for the northern Spain and Gulf of Cadiz and MEDITS for the Mediterranean. A total of 60 paired hauls were completed in the DEMERSALES survey, 43 for the ARSA and 37 hauls in the MEDITS. Comparisons between both vessels were done in each survey addressing: gear performance, total catch, commercial species catches, length distributions of the most representative species and analyzing the faunal fish assemblages detected. Differences between vessels were less significant for the DEMERSALES survey, with the higher catches, number of hauls and less variability; in the Gulf of Cadiz, catches of flatfish and some species of cephalopods were slightly higher in the R/V Miguel Oliver but no significant differences in the length distributions were found; for the MEDITS survey, catches by haul were lower, presenting a great diversity of species, thus complicating to separate the sources of variability due to the change of vessel from the uncertainty associated to the hauls. In general, catches in the R/V Miguel Oliver are similar to catches in the R/V Cornide de Saavedra. To verify the continuity and congruence of the time series special attention must be paid to the new surveys in the R/V Miguel Oliver to test if inter-calibration factors are needed for some species