bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of hunting season structure, weather and body condition on overwintering mallard Anas platyrhynchos survival
Authors: Dooley Joshua L. , Sanders Todd A. , Doherty Paul F.
Published: February 2011

Information on waterfowl survival during the overwintering season (i.e. autumn and winter), when hunting seasons occur, is important for making harvest management decisions. However, the relationship of overwintering survival to hunting season structure, weather and body condition are not well understood. We measured survival of 235 radio‐marked adult female and male mallards Anas platyrhynchos along the South Platte River corridor in northeastern Colorado, USA, during the overwintering seasons of 2005/06 (pilot year), 2006/07 and 2007/08, and we determined the primary factors affecting survival. Hunting was the most important factor affecting survival. Of mortality, 67% were direct results of hunting, and survival was lower during hunting periods compared to non‐hunting periods. Within hunting periods, survival was lowest during the first 2‐3 weekends of the hunting periods. During the seasons 2006/07 and 2007/08, survival of radio‐marked mallards was monitored during September‐February. The estimated survival was 0.65 (95% CI = 0.50 ‐ 0.78) for females and 0.54 (95% CI = 0.39 ‐ 0.68) for males during 2006/07, and 0.55 (95% CI = 0.40 ‐ 0.69) for females and 0.42 (95% CI = 0.28 ‐ 0.58) for males during 2007/08. We did not observe a strong correlation between body condition index and survival (= 0.36, SE = 0.43). Accumulated snowfall and daily minimum temperature were unimportant variables for predicting survival. Of hunting recoveries, 89% occurred in our study area, and 15% and 18% of radio‐marked mallards went missing during 2006/07 and 2007/08, respectively. Our results suggest that split hunting seasons are an effective management tool to increase hunter harvest and affect overwintering survival. Given a set bag limit and season length, managers may be able to increase hunter harvest by: 1) having hunting periods of at least three weeks in length, 2) including as many weekend days (i.e. Saturdays and Sundays) within hunting periods as possible and 3) interspersing hunting periods with non‐hunting periods of at least 2‐3 weeks.
Foraging location quality as a predictor of fidelity to a diurnal site for adult female American woodcock Scolopax minor
Authors: Doherty Kevin E. , Andersen David E. , Meunier Jed , Oppelt Eileen , Lutz R. Scott , Bruggink John G.
Published: February 2011

Quality of recently used foraging areas is likely an important predictor of fidelity to specific locations in the future. We monitored movement and habitat use of 58 adult female American woodcock Scolopax minor at three study areas in Minnesota, Wisconsin and Michigan, USA, during autumn 2002 and 2003, to assess the relationship between foraging habitat use decisions and environmental conditions at previously used foraging locations. We assessed whether habitat variables which related to food and weather were related to distance between locations on subsequent days of individual woodcock that choose diurnal foraging locations when they return from night‐time roosting locations. We predicted that woodcock would return to foraging locations used on the previous day (i.e. shorter distances between daily foraging locations) when environmental conditions on the prior day were favourable. Woodcock generally made short (i.e. 48% < 50 m and 91% < 400 m) between‐day movements, but also occasionally (∼ 7%) abandoned prior foraging areas. The primary determinants of woodcock movements during autumn (prior to migration) were low local food availability and potential for increased food availability elsewhere. The quality of foraging locations was an important predictor of future foraging habitat use for woodcock, consistent with the hypothesis that woodcock movement behaviour balances the risks associated with movement with the potential benefits of increased energy intake in new foraging areas.
Patterns of scat deposition by brown hyaenas Hyaena brunnea in a mountain savannah region of South Africa
Authors: Hulsman Alma , Dalerum Fredrik , Swanepoel Lourens , Ganswindt Andre , Sutherland Chris , Paris Monique
Published: February 2011

The brown hyaena Hyaena brunnea is a near threatened large carnivore inhabiting sub‐Saharan Africa. Like many other species of terrestrial carnivores, brown hyaenas often and repeatedly deposit scats at specific latrine sites as a means of olfactory communication. However, previous studies on brown hyaena latrine use have been constrained to the arid Kalahari region in southern Africa, an area of low resource abundance. To improve our understanding of geographic variation in the biology of this species, we monitored patterns of brown hyaena scat deposition in the Waterberg of northern South Africa, an area of higher net productivity than previous areas for published brown hyaena studies. Defecation rates at latrine sites were low in our study area (median: < 1 defecation in 30 days), but brown hyaenas visited sites significantly more often than they defecated at them (median: 2.6 visits/30 days). The temporal patterns of activity at defecation sites were significantly related to the overall temporal activity patterns of brown hyaenas on the roads within the reserve, and generally confirmed a nocturnal activity pattern in the species. Our result on brown hyaena scat deposition in the Waterberg region indicates a geographic variation in latrine use, and we suggest that such a variation could be linked to resource‐driven variation in social and spatial organisation.
Individual and environmental determinants of early brood survival in black grouse Tetrao tetrix
Authors: Ludwig Gilbert X. , Alatalo Rauno V. , Helle Pekka , Siitari Heli
Published: February 2011

In black grouse Tetrao tetrix the survival of juveniles from hatching until recruitment is a critical determinant of population growth. The proportion of juvenile survivors from hatching until recruitment declines continually, but juvenile mortality rates are commonly highest during approximately the first 10 days after hatching. Likely causes of mortality include adverse weather, predation and availability of food. Little is known, however, about how individual properties, such as body mass of hen or chicks and properties of the brood rearing environment (e.g. vegetation characteristics or weather conditions) interact with each other and/or with fluctuating levels of predator abundance in determining early brood survival, simply because such data are very scarce. Using an information‐theoretic approach, our paper identifies determinants of early daily survival rates of black grouse chicks in a managed forest landscape of central Finland. During the three years of our study, the proportion of hens losing their broods within 10 days after hatching varied between 0.08 and 0.36.The variation in daily survival rates of chicks was largely mediated by a combination of four key explanatory variables. Brood survival clearly increased with the extent of bilberry Vaccinium myrtillus cover, and was further affected by interactions of temperature and hatching date as well as temperature and chick body mass. Low temperatures consistently resulted in lower daily survival rates. An increase in temperature, however, was more beneficial for early hatchers and heavy chicks. There was no difference in survival between broods from yearling and adult hens and we found no effect of predator density, be it as main effect or as interaction with other variables, on the daily survival rates of chicks. Improving black grouse breeding success can be regarded as a key management target which may be critical for their recovery. Our results suggest that such management should favour protection or local recovery of bilberry, as well as integrate weather and climate changes into the equation of hunting management.
Does illegal hunting skew Serengeti wildlife sex ratios?
Authors: Marealle Wilfred N. , Foss⊘y Frode , Holmern Tomas , Stokke Bård G. , R⊘skaft Eivin
Published: February 2011

In this article we show that the population of Serengeti Masai giraffes Giraffa camelopardalis tippelskirchi is extremely female biased, particularly among newborns. Our results suggest that this might be a response to heavy illegal hunting and the continuous disturbance such activities cause on giraffes, as sex ratios were more female skewed in all age groups in areas with high risk of illegal hunting. Giraffes were also more vigilant and fled at longer distances in such areas. Such female skewed sex ratios have also been found in other Serengeti species such as the ostrich Struthio camelus, the impala Aepycerus melampus and the wildebeest Connochaetus taurinus. In all studies, the sex ratio was more female skewed in areas in which illegal hunting is common. We found that sex ratio in giraffe calves, particularly in areas with high risk of illegal hunting, were more female skewed than in subadults or adults, indicating a female biased sex ratio at birth. If wildlife species react to a constant human disturbance by conceiving female offspring, this might cause serious conservation challenges. Conservation managers must anyway take this into account when developing future hunting regimes, not only for giraffes but also for other ungulate species under constant stress. We discuss various hypotheses aiming at explaining the female biased sex ratio in giraffes. However, further studies are needed to disentangle the causes of the skewed sex ratio observed in our study.
Soils and forage quality as predictors of white‐tailed deer Odocoileus virginianus morphometrics
Authors: Jones Phillip D. , Strickland Bronson K. , Demarais Stephen , Rude Brian J. , Edwards Scott L. , Muir James P.
Published: February 2011

Biologists tasked with managing cervids could benefit from models predicting physical characteristics. Differences in white‐tailed deer Odocoileus virginianus morphometrics across soil resource areas in Mississippi, USA, provide opportunity to test the predictive capacity of soil chemical and forage quality variables. Using principal components analysis (PCA), we modeled variation in body mass and antler score of ≥ 1.5‐year‐old male deer against seven soil chemical variables and 12 forage quality variables to elucidate potential nutritional factors corresponding with physical variation among 21 deer populations. We developed separate sets of models at the levels of state and soil resource area (Delta, Thin Loess and Lower Coastal Plain) and compared statewide models with general linear models (GLM) that related deer morphometrics to nominal classification variables representing the three soil resource areas. PCA distinguished a gradient of increasing soil fertility and forage quality that explained 58% of body mass and 52% of antler score variation statewide. However, the GLM using soil resource area as the explanatory variable explained 78 and 61%, respectively, indicating that management models should use soil resource area to designate areas with broadly similar nutritional planes. Within soil resource areas, the region with the greatest soil fertility and forage quality (Delta) did not model successfully for either body mass or antler score. The Thin Loess was successfully modeled for antler score, but only the Lower Coastal Plain, which had the lowest level of soil and forage quality, was successfully modeled for both morphometric variables. The Delta may have represented an area with habitat quality sufficiently high to render small variations non‐influential. In contrast, the generally poorer soil quality of Thin Loess and Lower Coastal Plain soils and forages may act as a limiting factor on physical expression, which allowed some response to relatively small fluctuations in range quality. The potential utility of soil and forage metrics within soil resource areas to estimate deer physical qualities appears to be primarily for fine‐tuning estimates largely determined by factors such as density and land use.
Polémique anti-judaïque et émergence de l'Islam (7e-8e siècles)
Authors: Déroche Vincent
Published: February 2011

REB 57 1999 France p. 141

Vincent Déroche, Polémique anti-judaïque et émergence de l'Islam (7e -8e s.). — In the light of the recent thesis of D. Olster, in whose opinion anti-Jewish polemics of the 7th- 8th centuries had no other goal than to reinforce the political confidence of eastern Christians in the wake of Islam, we are reminded of the religious dimension of the conflict through an assessment of the important texts.
Les Stigand : Des Normands à Constantinople
Authors: Amsellem Emmanuelle
Published: February 2011

REB 57 1999 France p. 283

Emmanuelle Amsellem, Les Stigand : des Normands à Constantinople. — Odon Stigand went on a pilgrimage as far as Constantinople in the company of Robert of Normandy. The Chronicle of Ste-Barbe en Auge tells us that Odon, his eldest son, was in service to the Comneni and Doukai, and that his brother, Robert, entered in turn into imperial service and received as recompense the relics of St Barbe.
Der heilige Georg auf Siegeln einige neue Bullen mit Familiennamen
Authors: Wassiliou Alexandra-Kyriaki
Published: February 2011

This article presents a series of seals dating from the third quarter of the 1lth century through the 13th century. As the need arises, individuals are identified, family names are etymologically analysed and the origin and sphere of activity of the families themselves are commented on. Finally, a number of individuals who also appear on seals of approximately the same period are brought into discussion. What is common to all the seals is the presence of the image of saint George on the obverse. The article is introduced by a short survey of the saint's iconography and surnames on seals. The seals are part of the Tübingen Zamitz Collection and have been in the possession of the Staatliche Münzsammlung in Munich since late 1999.
Conservation biogeography of red oaks (Quercus, sectionLobatae) in Mexico and Central America
Authors: Torres‐Miranda Andrés , Luna‐Vega Isolda , Oyama Ken
Published: February 2011

•Premise of the study: Oaks are dominant trees and key species in many temperate and subtropical forests in the world. In this study, we analyzed patterns of distribution of red oaks (Quercus, sectionLobatae) occurring in Mexico and Central America to determine areas of species richness and endemism to propose areas of conservation.

•Methods: Patterns of richness and endemism of 75 red oak species were analyzed using three different units. Two complementarity algorithms based on species richness and three algorithms based on species rarity were used to identify important areas for conservation. A simulated annealing analysis was performed to evaluate and formulate effective new reserves for red oaks that are useful for conserving the ecosystems associated with them after the systematic conservation planning approach.

•Key results: Two main centers of species richness were detected. The northern Sierra Madre Oriental and Serranías Meridionales of Jalisco had the highest values of endemism. Fourteen areas were considered as priorities for conservation of red oak species based on the 26 priority political entities, 11 floristic units and the priority grid‐cells obtained in the complementarity analysis. In the present network of Natural Protected Areas in Mexico and Central America, only 41.3% (31 species) of the red oak species are protected. The simulated annealing analysis indicated that to protect all 75 species of red oaks, 12 current natural protected areas need to be expanded by 120000 ha of additional land, and 26 new natural protected areas with 512500 ha need to be created.

•Conclusions: Red oaks are a useful model to identify areas for conservation based on species richness and endemism as a result of their wide geographic distribution and a high number of species. We evaluated and reformulated new reserves for red oaks that are also useful for the conservation of ecosystems associated with them.
Maporal Virus as a Surrogate for Pathogenic New World Hantaviruses and its Inhibition by Favipiravir
Authors: Buys Kristin K , Jung Kie-Hoon , Smee Donald F , Furuta Yousuke , Gowen Brian B
Published: February 2011

Background:

Pathogenic hantaviruses geographically distributed in the Old World cause haemorrhagic fever with renal syndrome (HFRS), whereas New World hantaviruses are the aetiological agents of hantavirus cardiopulmonary syndrome (HCPS). Ribavirin, a drug associated with toxicities, is presently indicated for treatment of HFRS, whereas treatment of the more frequently lethal HCPS is limited to supportive care. Because of the need for safe and effective antivirals to treat severe hantaviral infections, we evaluated favipiravir (T-705) against Dobrava and Maporal viruses as representative Old World and New World hantaviruses, respectively. Dobrava virus causes HFRS in Europe. Maporal virus (MPRLV), recently isolated from western Venezuela, is phylogenetically similar to Andes virus, the principal cause of HCPS in Argentina.

Methods:

Hantavirus replication in the presence of various inhibitors was measured by focus-forming unit assays and quantitative reverse transcriptase PCR. Phylogenetic relationships were assessed by the neighbour-joining and bootstrap consensus methods.

Results:

Here, we show that infection of Vero E6 cells with MPRLV is dependent on β3 integrins, similar to that reported for pathogenic hantaviruses. Furthermore, by analysis of molecular determinants associated with the G1 glycoprotein cytoplasmic tail, we show the close genetic proximity of MPRLV to other HCPS-causing hantaviruses in these regions predictive of pathogenicity. We also demonstrate anti-hantavirus activity by favipiravir with inhibitory concentrations ranging from 65 to 93 μM and selectivity indices >50.

Conclusions:

Our data suggest that MPRLV may serve as a safer alternative to modelling infection caused by the highly lethal Andes virus and that hantaviruses are sensitive to the effects of favipiravir in cell culture.
Modelo conceptual del sistema acuífero de Enchereda (La Gomera, Islas Canarias): contribuciones a otras islas volcánicas
Authors: Izquierdo T. , Herrera R. , Márquez A.
Published: February 2011

La elaboración de modelos conceptuales en acuíferos de islas volcánicas presenta una elevada dificultad debido a la complejidad estructural de los materiales volcánicos, incrementada por 1) los procesos de destrucción (p. ej., deslizamientos de flanco) y 2) la intrusión de diques, que pueden actuar como zonas de flujo preferente o sobreelevando el agua localmente. En algunos casos, la falta de información hidrogeológica en el interior de las islas dificulta aún más la caracterización del funcionamiento de los acuíferos en estas zonas. En este trabajo se evalúa el papel de los diques y de los depósitos volcanoclásticos en el flujo regional de la zona de Enchereda (La Gomera, Islas Canarias) y en particular, en su zona más elevada. En esta zona se definen tres unidades hidroestratigráficas: los Basaltos Antiguos Inferiores moderadamente permeables; a techo las Brechas Volcánicas de baja permeabilidad; y por encima los Basaltos Antiguos Superiores, permeables. Las brechas parecen actuar como límite inferior impermeable del acuífero y en su reconstrucción se observa que presentan una geometría coherente con un buzamiento general hacia el ESE de aproximadamente 13º, condicionando el flujo regional del agua en el acuífero. La cartografía de los diques mediante fotografía y ortofotografía aérea así como en campo y en el interior de la galería de Ipalán, ha permitido identificar cuatro familias de diques. Los diques NO-SE son los más abundantes, con una densidad máxima de más de 10 diques/100 m, similar a otras zonas de rift en volcanes oceánicos. Estos diques son paralelos al flujo regional del agua en el acuífero y actuarían por tanto como zonas de flujo preferente, mientras que los diques con direcciones N-S y NE-SO sobreelevarían el nivel piezométrico, generando una superficie escalonada, al ser perpendiculares a la dirección flujo. Por último, los diques E-O no parecen influir de manera significativa en el acuífero. Nuestros resultados plantean la necesidad de reevaluar principalmente la influencia de los diques en el flujo regional de acuíferos en otras islas volcánicas en las que su papel se ha minimizado, ya que la superposición de diferentes familias de diques puede condicionar el movimiento del agua en el acuífero.
An Ambient Intelligence Based Multi-Agent System for Alzheimer Health Care
Authors: Tapia Dante I. , Corchado Juan M.
Published: February 2011

This article describes ALZ-MAS; an Ambient Intelligence based multi-agent system aimed at enhancing the assistance and health care for Alzheimer patients. The system makes use of several context-aware technologies that allow it to automatically obtain information from users and the environment in an evenly distributed way, focusing on the characteristics of ubiquity, awareness, intelligence, mobility, etc., all of which are concepts defined by Ambient Intelligence.
Adaptive Awareness of Hospital Patient Information through Multiple Sentient Displays
Authors: Favela Jesus , Tentori Monica , Segura Daniela , Berzunza Gustavo
Published: February 2011

Sentient computing can provide ambient intelligence environments with devices capable of inferring and interpreting context, while ambient displays allow for natural and subtle interactions with such environment. In this paper we propose to combine sentient devices and ambient displays to augment everyday objects. These sentient displays are aware of their surroundings while providing continuous information in a peripheral, subtle, and expressive manner. To seamlessly convey information to multiple sentient displays in the environment, we also propose an approach based on abstract interfaces which use contextual information to decide which display to use and how the information in the display changes in response to the environment. Our approach is illustrated through a hospital monitoring application. We present the design of two sentient displays that provide awareness of patient’s urine outputs to hospital workers, and how contextual information is used to integrate the functionality of both displays.
Issues for the Evaluation of Ambient Displays
Authors: Shen Xiaobin , Vande Moere Andrew , Eades Peter , Hong Seok-Hee
Published: February 2011

This article is motivated by two evaluation case studies of ambient information displays. Firstly, an intrusive evaluation of a display called MoneyColor concentrates on the relationship between “distraction” and “comprehension”. This revealed that the comprehension is in direct proportion to display-distraction, but there is no clear relationship between comprehension and self-interruption. Secondly, a non-intrusive evaluation of a display called Fisherman described a quantitative measurement of user “interest” and applied this measurement to investigate “evaluation time” issue. These experiments give some insight into number of issues in evaluation of ambient displays.
Routing in Opportunistic Networks
Authors: Nguyen Hoang Anh , Giordano Silvia
Published: February 2011

In Opportunistic Networks (OppNets), mobile devices transmit messages by exploiting the direct contacts, without the need of an end-to-end infrastructure. Disconnections of nodes and high churn rates are normal features of opportunistic networks. Hence, routing is one of the main challenges in this environment. In this article, we provide a survey of the main routing approaches in OppNets and classify them into three classes: context-oblivious, mobility-based, and social context-aware routing. We emphasize the role of context information in forwarding data in OppNets, and evaluate the relative performance of the three routing techniques. Finally, we present how context-based information is used to route data in a specific subclass of OppNets: Sensor Actor Networks (SANETs).
Easing the Integration and Communication in Ambient Intelligence
Authors: Gómez Javier , Montoro Germán , Haya Pablo A. , García-Herranz Manuel , Alamán Xavier
Published: February 2011

In this article we present a middleware developed for Ambient Intelligence environments. The proposed model is based on the blackboard metaphor, which is logically centralized but physically distributed. Although it is based on a data-oriented model, some extra services have been added to this middle layer to improve the functionality of the modules that employ it. The system has been developed and tested in a real Ambient Intelligence environment.
Ambient Middleware for Context-Awareness (AMiCA)
Authors: Lee Karen , Lunney Tom , Curran Kevin , Santos Jose
Published: February 2011

Recent advances in wireless networking technologies and the growing success of mobile computing devices are enabling new classes of applications. Distributed applications running in a mobile environment are often subject to varying qualities of service from the underlying infrastructure. The objective of the work outlined in this research is the development of an Ambient Middleware framework for Context-awareness which will offer new opportunities for application developers. Context-awareness has been a central issue in Ambient Intelligent research for the last decade. Ambient Intelligent systems and applications represent extremely complex and heterogeneous distributed systems, composed of hardware and software, and the need for middleware for seamless integration is well recognised. Research shows that existing middleware solutions need to evolve, thus permitting the dissemination of omnipresent attributes within the Ubiquitous and Pervasive computing environments of today. To determine the effectiveness of this middleware framework, a cloud computing based application will be developed.
WebGuard
Authors: Hammami Mohamed , Chen Liming
Published: February 2011

This paper describes a Web filtering system “WebGuard,” which aims to automatically detect and filter adult content on the Web. WebGuard uses data mining techniques to classify URLs into two classes: suspect URLs and normal URLs. The suspect URLs are stored in a database, which is constantly and automatically updated in order to reflect the highly dynamic evolution of the Web. When working, WebGuard simply captures a user’s URL, matches it with the suspect URLs stored in the database and takes an appropriate action — filtering or blocking — according to the result of the analysis. We started out with a study of most existing software so as to get to know the possibilities and functionalities available on the market at the moment. This phase enabled us to better evaluate the performances of our product as it was being developed. Thus, the second phase of our work was devoted to research into the usual algorithms regarding their advantages and drawbacks. Having gathered this knowledge, we are currently implementing a system that will combine several algorithms in order to increase the software’s performance. Our preliminary results show that it can detect and filter adult content effectively.
The Use of Efficient Cost Allocation Mechanisms for Congestion Pricing in Data Networks with Priority Service Models
Authors: Beltran Fernando , Garcia-Diaz Cesar
Published: February 2011

This paper demonstrates the application of two efficient cost allocation mechanisms on a simple FIFO network model in order to find congestion-based prices for network access services. It is shown that it is possible to obtain congestion-dependent prices in data networks (such as the Internet), establishing simultaneously different service quality levels among the users. The rationale behind these efficient distribution mechanisms is an axiomatic framework that determines a set of basic principles, highlighting the need for a fair allocation. Due to the characteristics of the price mechanisms and the possibilities of the parameter space in which these mechanisms might be applied, it is also shown that, in some cases, such mechanisms need additional weighting schemes in order to establish coherent differences among the service quality levels. In conclusion, even though the axiomatic framework guarantees efficient allocation, checking coherency in its use is left to the network manager.
Query Processing Strategies for Location-Dependent Information Systems
Authors: Jayaputera James , Taniar David
Published: February 2011

The demand of mobile Location Dependent Information Services (LDIS) has fueled in recent years. However, the request of a correct answer in a mobile environment needs to have more attention. This is due to the scope of query based on a location of users. In this article, we propose a new approach to generate a query result for Location-Dependent Information Services. It argues that choosing a square as a scope brings a bigger chance to get rare targets. In addition, avoiding resubmitting the same queries when the query results missed reduces bandwidth at server and client sides. Some different situation examples and evaluations show the efficiency of our proposed algorithm. The aim of our approach is to reduce a continuous query submission, speed up the processing time, and reduce the server load while a server is processing a user query.
MANET
Authors: Dhar Subhankar
Published: February 2011

This paper presents the current state of the art of mobile ad hoc network and some important problems and challenges related to routing, power management, location management as well as multimedia over ad hoc networks. A mobile ad hoc network (MANET) is a temporary self-organizing network of wireless mobile nodes without the support of any existing infrastructure that may be readily available on the conventional networks. Since there is no fixed infrastructure available for MANET with nodes being mobile, routing becomes a very important issue. In addition, we also explain the various emerging applications and future trends of MANET.
Exposing the Wired Equivalent Privacy Protocol Weaknesses in Wireless Networks
Authors: Curran Kevin , Smyth Elaine
Published: February 2011

This article highlights a number of security issues within wireless networks. Signal leakage for instance, means that network communications can be picked up outside the physical boundaries of the building in which they are being operated, meaning that a hacker can operate from the street outside or discretely from blocks away. In addition to signal leakage, the Wired Equivalent Privacy (WEP) protocol is inherently weak. There are also various other attacks that can be initiated against WLANs, all with detrimental effects. During our investigation, a war-driving expedition was conducted to ascertain the number of unprotected WLAN devices in use locally. We concluded that there was an apparent and serious lack of security on WLAN devices. Even those users that have implemented WEP do not seem to realize just how weak this protocol is or how their networks could be affected.
The Economic Value of Modularity in the IPQoS Network
Authors: Kim Hak Ju
Published: February 2011

As uncertainty in the markets and technologies of the network industry increases, a flexible architecture is needed by network service providers to maintain a competitive advantage. Since complete replacement of existing networks is not practical, and since it is costly for one operator to manage everything in a network, modularity in network design may be an efficient approach. This article is to construct a theoretical framework to support the decisions of network service providers in network design, to modularize or not and, if so, by how much. We develop a model to show the extent of modularity in network design by combining two important concepts: modularity from management and complementarity from economics. This will show how the extent of modularity in networks affects the value of networks with complementary components under uncertainty. For empirical testing, a simple QoS service model network is designed and simulated.
Strip-Mining the Web with SAIM
Authors: Schwartz David G. , Sadan Zac
Published: February 2011

There is no shortage of knowledge waiting to be mined on the Web. But there is a difference between mining to the depths of the Web and examining what is occurring on its surface. In this article, the authors argue that the search for actionable knowledge should start as close as possible to the user, which, in today’s technological environment, means tapping into Instant Messages. They present a System for the Analysis of Instant Messages, explain the architectural and operational motivation, and show how instant messages can be mined to produce a new source of Web-based knowledge.
Gigabit Ethernet Implementation
Authors: Sarkar Nurul I. , Byrne Catherine , Al-Qirim Nabeel A.Y.
Published: February 2011

Although Ethernet technology is still the most popular LAN technology in use today at the desktop, the throughput offered by the 10 and 100 Mbps Ethernet is inadequate for high bandwidth networking applications such as real-time visualisation, high-resolution graphics, multimedia and Web applications. Gigabit Ethernet (GigE) technology provides 1,000 megabits per second (i.e., one gigabit per second) at more reasonable cost than the other technologies of comparable speed and therefore it is a natural upgrade strategy for many legacy Ethernet networks. This paper reports on a case study of a large New Zealand organization focusing on the level of GigE deployment, design, planning and implementation, network performance testing, problems encountered and future plans. Our findings show the feasibility and practicability of deploying GigE technology in high-speed networking applications such as campus- and corporate-wide local area networks.
Cooperative Data Caching and Prefetching in Wireless Ad Hoc Networks
Authors: Denko Mieso K.
Published: February 2011

This article proposes a cooperative data caching and prefetching scheme for Mobile Ad Hoc Networks (MANETs). In this scheme, multiple hosts cooperate in both prefetching and caching commonly used data. To reduce communication and computational overhead, we use a clustering architecture for the network organization. A weak consistency based on time to live value was used to maintain data consistency. A hybrid cache replacement policy that uses frequency of access and the reference time was employed. The effects of cache size, mobility, and prefetching threshold on the network performance were investigated in a discrete event simulation environment. The contribution of intra-cluster and inter-cluster information to overall data accessibility ratio was also investigated. The simulation results indicate that the proposed scheme improves both data accessibility and query delay at relatively lower prefetch thresholds, larger cache sizes, and moderate mobility.
Intelligent Reasoning Approach for Active Queue Management in Wireless Ad Hoc Networks
Authors: Natsheh Essam , Jantan Adznan B. , Khatun Sabira , Subramaniam Shamala
Published: February 2011

Mobile ad hoc network is a network without infrastructure where every node has its own protocols and services for powerful cooperation in the network. Every node also has the ability to handle the congestion in its queues during traffic overflow. Traditionally, this was done through Drop-Tail policy where the node drops the incoming packets to its queues during overflow condition. Many studies showed that early dropping of incoming packet is an effective technique to avoid congestion and to minimize the packet latency. Such approach is known as Active Queue Management (AQM). In this article, an enhanced algorithm called fuzzy-AQM is suggested using a fuzzy logic system to achieve the benefits of AQM. Uncertainty associated with queue congestion estimation and lack of mathematical model for estimating the time to start dropping incoming packets makes the fuzzy-AQM algorithm the best choice. Extensive performance analysis via simulation showed the effectiveness of the proposed method for congestion detection and avoidance improving overall network performance.
A Heuristic Search Algorithm for the Cellular Telecommunication Network Expansion Problem
Authors: Oh Joon-Yeoul , Mullen John P.
Published: February 2011

This article proposes a very effective heuristic algorithm to address the network expansion problem, and it discusses step-by-step procedures of the proposed algorithm in detail. The input to the algorithm is based on a binary integer programming formulation of the network problem. The solution specifies the connections of each component, cell sites, hubs, and mobile telephone switching office and satisfies the redundancy requirements for each cell site to ensure the traffic flow and to backup any disconnection. The algorithm generates lower and upper bounds on cost of the exact solution, and preliminary testing indicates that it generates very effective results efficiently. The authors hope that in presenting such an algorithm, designers of very large cellular network expansions will have a tool to obtain significantly good solutions in a reasonable time.
Simultaneous Mobility
Authors: Wong K. Daniel , Ng Seh Chun , Woon Wei Lee
Published: February 2011

To realize the full potential of mobile multimedia, mobility protocols are needed to handle situations when nodes move while in a multimedia session. Many mobility protocols have been proposed for IP-based networks. In some important cases in using these mobility protocols such as mobile IPv6 with route optimization, a problem can arise when both nodes are mobile and move simultaneously. The problem is that both sides’ binding updates could be lost. A few solutions have recently been proposed. A crucial indicator of the importance of the simultaneous mobility problem, and of its solutions, is the probability of its occurrence. However, previous articles have used only a simple analytical model to estimate the probability of the simultaneous mobility problem occurring. In this article, we present new and more accurate results on the variation of this probability with a number of critical variables.
A Marketable Quality and Profit-ability Model Considering Service Providers and Consumers Relation
Authors: Fukuda Heihachiro , Barolli Valbona , Barolli Leonard , Takizawa Makoto
Published: February 2011

In this article, we present a model to evaluate both marketable quality and profitability consid-ering service providers and consumers relation. We use the real values of some leading Japa-nese manufacturing corporations as virtual data of service providers to our proposed model to analyze its accuracy. By analysis, we found that the theoretical and real standard values of the marketable quality indicator for the rate of operation at the break-even point were both 0.6 (that is 60%). This shows that the proposed model has a good approximation. From the fair relation of network providers and consumers, we provided the network pricing guidelines for the maximum profitability while enhancing the marketable quality.
Wireless Proxy
Authors: Vilas Manuel , Pañeda Xabiel  G. , Melendi David , García Roberto , García Victor
Published: February 2011

This article introduces a distributed system, called wireless proxy, to mitigate the effects of user mobility over streaming services on IEEE 802.11 wireless LANs (WLANs). It argues that a handoff procedure totally controlled by the client, depending on client mobility and configuration, can have negative effects over streaming services. In this way, mobile clients that remain associated with their current access point (AP) in poor channel conditions, severely affect the performance of streaming services. The presented distributed system monitors client mobility and induces mobile client handoffs when channel conditions worsen. Also, the system compensates streaming client and server underestimations of channel conditions. The obtained improvements using wireless proxy are experimentally tested using one of the most extended commercial streaming platforms and off-the-shelf WiFi devices. The main contribution of the developed system is that it works with unmodified IEEE 802.11 wireless NICs and APs, such as the ones widely deployed nowadays.
Multicast and Unicast ODMRP Routing in Ad hoc Networks Based on Quality of Service Support and Local Recovery Approach
Authors: Effatparvar Mehdi , Darehshoorzadeh Amir , Dehghan Mehdi , EffatParvar Mohammad Reza
Published: February 2011

An ad hoc network is comprised of mobile hosts without any wired infrastructure support. The primary concerns in ad hoc networks are bandwidth limitation and unpredictable dynamic topology. Therefore, efficient bandwidth utilization is crucial in routing protocols. Reliable multicast plays a significant role in many applications of mobile ad hoc networks (MANETs). The on-demand multicast routing protocol (ODMRP) was designed for multicast routing in ad hoc networks. However, ODMRP supports unicast routing too. It is very important to efficiently allocate and consume link bandwidth in this protocol, especially when many sessions are working concurrently. In this article, we propose a new method for estimating bandwidth in multicast protocols and also a new technique for supporting QoS routing in multicast and unicast ODMRP by making an acceptable estimation of available and required bandwidth. Also, we propose a local recovery approach to design a reliable multicast algorithm. Simulation results show that using QoS routing for ODMRP improves network performance in presence of mobility, by searching for suitable paths. By local recovery approach, nodes can join to multicast group in minimum time, and data delivery will be increased.
Precise Analysis and Evaluation of OFDM Systems over a Mobile Frequency-Selective Nakagami-m Fading Channels
Authors: Khedr Mohmaed Essam
Published: February 2011

In this article, the symbol error probability (SEP) of OFDM systems using M-ary coherent demodulation communicating over time-varying sum of Nakagami-m fading channels is analyzed. The focus of this article is on the evaluation of OFDM signals in mobile radio applications, such as IEEE 802.11a, IEEE 802.16a, and digital video broadcasting (DVB) systems. The time variations of the channel during one OFDM symbol interval destroy the orthogonality of the adjacent subcarriers and generate power leakage among the subcarrier, known as inter-carrier interference (ICI). We first present an integral solution for the probability density function (PDF) of the sum of Nakagami-m random vectors (RVs). Second, we used this PDF expression to obtain an exact closed form for the error probability. The error rate analysis is then extended to systems using multichannel reception with maximal ratio combining (MRC). Based on Jakes’ model for Doppler effects, and an exponential multipath intensity profile, numerical results for the error probability are illustrated for several mobile speeds. An interesting observation was concluded that depending on the number of the channel taps, the error rate performance does not necessarily improve with increasing Nakagami-m fading parameter.
Open Source Tool For Network Monitoring
Authors: Formoso Vreixo , Cacheda Fidel , Carneiro Víctor , Valiño Juan
Published: February 2011

Even though monitoring tools are essential to the management of communications networks, Open Source applications still confront their potential users with considerable problems. This work analyses the limitations of the currently existing tools and presents the development of a new tool that solves most of those problems. The tool is based on a new architecture of objects and remote method invocation and allows both centralized and distributed monitoring. Its configuration through web interface, its support to monitoring templates, and its flexibility make it particularly interesting for a large number of users in search of a strong but easily configurable system. The proposed extension system is based on plug-ins and it is highly innovative because of its power and simplicity. Finally, the configuration simplicity and other essential improvements of the proposed system are successfully tested in a real environment.
Comparison of Policies for Epidemic Broadcast in DTNs under Different Mobility Models
Authors: Giudici Francesco , Pagani Elena , Rossi Gian Paolo
Published: February 2011

The broadcast diffusion of messages in Delay Tolerant Networks (DTNs) is heavily dependent on nodes mobility, since protocols must rely on contact opportunities among devices to diffuse data. This work is a first effort to study how the dynamics of nodes affect both the effectiveness of the broadcast protocols in diffusing data, and their efficiency in using the network resources. The paper describes three control mechanisms. The mechanisms characterize a family of protocols able to achieve some awareness about the surrounding environment, and to use this knowledge in order to keep the broadcast overhead low, while ensuring high node coverage. Simulation results identify the winning mechanisms to diffuse messages in DTNs under different conditions.
Reservation MAC protocols for Ad-Hoc Networks
Authors: Boudour Ghalem , Teyssié Cédric , Zoubir Mammeri
Published: February 2011

Multimedia and real-time applications require bandwidth guarantees, which may be achieved by resource reservation. Several researches were done to propose efficient reservation MAC protocols for ad-hoc networks. In these schemes, channel is segmented into super-frames composed of fixed number of slots. They allocate slots to each traffic source, and make sure that neighbor nodes record the reservation in order to ensure consistency of reservations between neighbor nodes. However, resource reservation in ad-hoc networks remain a very challenging task due to the instability of radio channels, node mobility and lack of coordination between mobile nodes. Proposed reservation MAC protocols like CATA, FPRP, R-CSMA and SRMA/PA have limitations and are suitable only for particular situations. In this paper, we propose a comparative analysis of the most representative reservation MAC protocols. We identify the major issues unresolved by reservation MAC protocols. A performance evaluation and comparative analysis with the IEEE 802.11e are achieved through the NS-2 simulator.
Use of Traffic Separation Techniques for the Transport of HSPA and R99 Traffic in the Radio Access Network with Differentiated Quality of Service
Authors: Li Xi , Zaki Yasir , Weerawardane Thushara , Timm-Giel Andreas , Görg Carmelita , Malafronte Gennaro Ciro
Published: February 2011

This article presents various traffic separation approaches to transmit HSPA (HSDPA/HSUPA) traffic in the existing ATM-based UMTS Radio Access Network, together with Release 99 (R99) traffic. The traffic separation technique enables QoS differentiations of HSPA and R99 traffic, while aiming to achieve a maximum utilization of the transport resources in the radio access network. The potential benefit of applying traffic separation and its impact on the performance of the transport network as well as the end users are explored in this article. The quantitative evaluations are provided by simulations. The results presented are obtained from a UMTS simulation model developed in this work which can transmit HSDPA and HSUPA traffic as well as R99 traffic simultaneously. The presented results demonstrate that applying traffic separation between HSPA and R99 traffic can considerably improve the performance of both HSPA and R99 traffic, and as well bring significant gain on efficient bandwidth utilization.