5,103 research outputs found
Signalling in voice over IP Networks
Voice signalling protocols have evolved, keeping with the prevalent move from circuit to packet switched networks. Standardization bodies have provided solutions for carrying voice traffic over packet networks while the main manufacturers are already providing products in workgroup, enterprise, or operator portfolio. This trend will accrue in next years due to the evolution of UMTS mobile networks to an “all-IP” environment. In this paper we present the various architectures that are proposed for signalling in VoIP, mainly: H.323, SIP and MGCP. We also include a brief summary about signalling in classical telephone networks and, at the end, we give some ideas about the proposed “all-IP” architectures in UMTS 3G mobile networks.Publicad
An Instructional Approach to Explore Poverty and Immigration: Using Three Children’s Books That Pack a Punch
Contemporary children’s literature can be used as an instructional approach to examine a variety of critical issues that are presented in multicultural education and culturally responsive teaching college courses. The author discusses the benefits of using children’s literature to examine poverty and immigration; his recommendations for selecting the right books and stories; and his experiences using three children’s books: Walk with Me (2017), Two White Rabbits (2015), and Jimmy the Greatest! (2015), all created by the same author and illustrator, Jairo Buitrago and Rafael Yockteng. Each book is carefully reviewed, and followed by a sample of critical thinking questions used to raise college students’ awareness of matters that impact the lives of children they will serve
Convergence: How Five Trends Will Reshape the Social Sector
This report highlights five key trends and how their coming together will shape the social sector of the future. Based on extensive review of existing research and in-depth interviews with thought leaders and nonprofit leaders and activists, it explores the trends (Demographic Shifts; Technological Advances; Networks Enabling Work to be Organized in New Ways; Rising Interest in Civic Engagement and Volunteerism; and Blurring of Sector Boundaries) and looks at the ways nonprofits can successfully navigate the changes. The monograph is by La Piana Consulting, a national firm dedicated to strengthening nonprofits and foundations
PACE: Simple Multi-hop Scheduling for Single-radio 802.11-based Stub Wireless Mesh Networks
IEEE 802.11-based Stub Wireless Mesh Networks (WMNs) are a cost-effective and flexible solution to extend wired network infrastructures. Yet, they suffer from two major problems: inefficiency and unfairness. A number of approaches have been proposed to tackle these problems, but they are too restrictive, highly complex, or require time synchronization and modifications to the IEEE 802.11 MAC.
PACE is a simple multi-hop scheduling mechanism for Stub WMNs overlaid on the IEEE 802.11 MAC that jointly addresses the inefficiency and unfairness problems. It limits transmissions to a single mesh node at each time and ensures that each node has the opportunity to transmit a packet in each network-wide transmission round. Simulation results demonstrate that PACE can achieve optimal network capacity utilization and greatly outperforms state of the art CSMA/CA-based solutions as far as goodput, delay, and fairness are concerned
Constrained Variational Calculus for Higher Order Classical Field Theories
We develop an intrinsic geometrical setting for higher order constrained
field theories. As a main tool we use an appropriate generalization of the
classical Skinner-Rusk formalism. Some examples of application are studied, in
particular, applications to the geometrical description of optimal control
theory for partial differential equations.Comment: 25 pages; 4 diagram
Dades preliminars sobre la poblaciĂł de Mauremys leprosa (Testudines: Geoemydidae) d'Alcoi (Alacant)
Es proporcionen dades sobre les caracterĂstiques morfomètriques i l'estructura d'una poblaciĂł detortuga d'aigua ibèrica (Mauremys leprosa) del riu Serpis al seu pas per Alcoi, SE d'Espanya, una zonaon prĂ cticament no consta informaciĂł prèvia sobre l'espècie. Entre setembre i octubre de 2014 escapturaren 18 individus. La raĂł de sexes no era equilibrada, en estar molt esbiaixada vers els mascles(4.5:1). El percentatge d'individus juvenils Ă©s menor que el d'adults. Les femelles assolixen una midamitjana mĂ©s gran que els mascles. Es calcula que la poblaciĂł pot estar formada per 64 exemplars.Preliminary data on the Mauremys leprosa (Testudines: Geoemydidae) populationfrom Alcoi (Alacant)We provide data on the morphometric characteristics and structure of a population of the stripeneckedterrapin (Mauremys leprosa) from the Serpis river (Alcoi, SE Spain), an area where barely anyprevious information for the species exists. 18 individuals were captured between September 2014 andOctober 2014. The ratio of sexes was not even and males outnumbered females (4.5:1). The percentageof juveniles was less than that of adults. Females reached a greater average size than males. We calculatethat the total population is made up of 64 individuals
Determinació experimental del camp magnètic terrestre
La majoria de la gent -i els nostres alumnes tambĂ©- sap que una brĂşixola s'orienta vers el nord o que els pols iguals dels imants es repel·leixen i els distints s'atrauen, però sovint poca cosa mĂ©s. Amb les experiències que mostrem es pretĂ©n aprofundir en aquests fenòmens per comprendre un poc millor quina Ă©s la fĂsica que s'hi amaga darrere
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Sceloporus heterolepis
Number of Pages: 3Integrative BiologyGeological Science
Sexual dimorphism in a Mauremys leprosa (Testudines: Geoemydidae) population from south-eastern Spain with emphasis on the carapace shape
Les dades biomètriques d'una població de tortuga d'aigua ibèrica, Mauremys leprosa (Schweiger, 1812), foren estudiades per provar l'existència de dimorfisme sexual en la mida i/o la forma. El paquet de dades fou analitzat amb una anà lisi de la covarià ncia (ANCOVA). Les femelles adultes assolixen mides més grans que els masdes i presenten un creixement al·lometric. Comparant mascles i femelles d'igual longitud de closca, les femelles presenten una closca més ampla i alta, aixà com un plastró més llarg i ample.
Els nostres resultats són congruents amb la teoria de la selecció per fecunditat, ja que les diferències observades permetrien que les femelles tingueren més descendència. Els mascles tenen una dosca més xicoteta i hidrodinà mica, el que podria tindre un paper clau com a comportament antidepredador durant l'època de cerca de parella.
Suggerim que les comparacions intra i interpoblacions poden aportar llum sobre els patrons adaptatius d'esta tortuga aquà tica.Les dades biomètriques d'una població de tortuga d'aigua ibèrica, Mauremys leprosa (Schweiger, 1812), foren estudiades per provar l'existència de dimorfisme sexual en la mida i/o la forma. El paquet de dades fou analitzat amb una anà lisi de la covarià ncia (ANCOVA). Les femelles adultes assolixen mides més grans que els masdes i presenten un creixement al·lometric. Comparant mascles i femelles d'igual longitud de closca, les femelles presenten una closca més ampla i alta, aixà com un plastró més llarg i ample.
Els nostres resultats són congruents amb la teoria de la selecció per fecunditat, ja que les diferències observades permetrien que les femelles tingueren més descendència. Els mascles tenen una dosca més xicoteta i hidrodinà mica, el que podria tindre un paper clau com a comportament antidepredador durant l'època de cerca de parella.
Suggerim que les comparacions intra i interpoblacions poden aportar llum sobre els patrons adaptatius d'esta tortuga aquĂ tica
Multicast traffic aggregation in MPLS-based VPN networks
This article gives an overview of the current
practical approaches under study for a scalable implementation of multicast in layer 2 and 3 VPNs over an IP-MPLS multiservice network. These proposals are based on a well-known technique: the aggregation of traffic into shared
trees to manage the forwarding state vs. bandwidth saving trade-off. This sort of traffic engineering mechanism requires methods to estimate the resources needed to set up a multicast shared tree for a set of VPNs. The methodology proposed in this article consists of studying the effect of aggregation obtained by random shared
tree allocation on a reference model of a representative network scenario.Publicad
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