The recharge - discharge aspects of Green Valley, Pima County, Arizona

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Rethinking the Role of Virtual Communities in Terrorist Websites

Researchers have established that most extremist websites seek to fulfill five basic goals: to disseminate propaganda, organize the membership, communicate information, fundraise, and recruit new members. In 2001, Jenine Abboushi Dallal suggested that terrorists were embracing the Web as a platform from which to recast their images.In her view, extremist groups went online not so much to engage in dialogue, but rather to offer a counter information system, and to create a virtual community. Dallal contended that these sites were not meant to be participatory or interactive, but rather were created to promote a tightly controlled authoritarian narrative

Sap flow and heat transport in trees: An asymptotic and numerical study

Transport of fluid and heat inside a tree, and the interchange of water and energy between the tree and the environment, are topics that have been and continue to be areas of active research in plant physiology, agriculture and environmental studies. Many models have been proposed to describe the flow of sap inside the tree, and to connect it to the driving transpiration rate, with various levels of complexity, and with different levels of abstraction. Most existing models are 1D models and many only attempt to get numerical results, without much analysis. For our work, we adopt a porous medium model that has been verified experimentally [Chuang et al., Ecological Modelling, 191(3):447-468, 2006]. We generalize this 1D model to a 3D axisymmetric geometry, where flow is transpiration driven and has anisotropic and spatially dependent hydraulic conductivity. Through asymptotic analysis, we derive approximate solutions that produce the axial and radial trunk sap fluxes for a given transpiration function. We validate the analytical solutions using a second order finite difference scheme. Next we use our solution formulas to tackle the inverse problem of determining spatial and temporal components of transpiration given a discrete set measurements of the trunk sap flux. Finally, we compare our results to some experimental data on radial variations of sap flux. As for the heat transport problem, previous work related to trees discuss special cases of the problem, while giving detailed accounts and specific formulas of the boundary conditions, like wind and solar radiation effects. Most of this work does not include the possible effects of advection owing to sap flux, and does not discuss the effects of spatial variation in saturation on the thermal diffusivity. Assuming local thermal equilibrium for porous media, we propose a simple advection-diffusion model, with general boundary conditions, and derive Fourier-Bessel series solutions for the various possible cases suggested by dimensionless parameters

Rethinking the role of virtual communities in terrorist websites

This study analysed the discursive strategies and representations of virtual communities on 38 terrorist-related websites between 2009 and 2010. Many security officials, policy analysts, and researchers are quick to identify the internet as a powerful terrorist recruiting tool that poses a growing security threat. Some worry that rapidly evolving technical capabilities offer terrorist groups a new strategic weapon with which to attack their enemies. Al Qaeda and the Zapatista National Liberation Army (EZLN) in Mexico were among the first such organizations to lead the migration of terrorist rhetoric to the Web, spearheading the exponential growth of such sites from a mere dozen in 1997 to more than 6,000 today. Researchers have established that most extremist websites seek to fulfill five basic goals: to disseminate propaganda, organize the membership, communicate information, fundraise, and recruit new members. In 2001, Jenine Abboushi Dallal suggested that terrorists were embracing the Web as a platform from which to recast their images. In her view, extremist groups went online not so much to engage in dialogue, but rather to offer a "counter information system," and to create a virtual community. Dallal contended that these sites were not meant to be participatory or interactive, but rather were created to promote a tightly controlled authoritarian narrative. Given the rapid proliferation of participatory applications on the Web in recent years, we set out to examine whether terrorism-related websites had embraced the Web 2.0 interactive applications that build community through commentary, social networking, and streaming video. Is there evidence that the internet has successfully generated virtual communities around websites run by terrorist groups? To answer this question, between 2009 and 2010 the authors analysed the discursive strategies and representations of virtual communities on 38 terrorist-related websites, 28 published in Arabic and 10 in Spanish (see Appendix A). Thecontent analysis identified in each case: 1) the sender of a message; 2) the content of that message; 3) the intended publics (readers of the message); and, 4) the interactive and multimedia features available to users of that particular website. The 38 coded websites were filtered from an initial list of 80 Muslim-based and 20 Spanish-language extremist sites identified in studies conducted since 2000. For the purposes of this analysis, "extremist" sites were defined as sites that explicitly endorsed hatred and violence, and actively promoted their ideologies online. The filtered core list was expanded using the external links on each site, the Google search engine in Arabic and Spanish, and the back-link function of BacklinkWatch (this function helps researchers determine what websites link to the website they are studying)

The Use of the Internet as a Communication Medium by Extremist Muslim Groups: A Content Analysis of Web Sites

The use of Web sites by terrorist groups has been evident since the mid 1990s. Security experts and researchers have identified terror-related Internet activity as a growing area of concern, especially following the attacks of September 11, 2001. Terrorist groups using the Internet pose two distinct threats. The first is cyberterrorism: terrorists using the Internet destructively and directly to bring about harm to persons or property, including, attacks on Web sites. The second is the use of the Internet as a communication medium to further the cause of terrorism or a particular organization. As of 2008, Weimann (2008b) estimated that over 6,000 terrorist Web sites exist, but the definition of a terrorist Web site is not always clear. This study analyzed the content of 30 extremist sites and defined those as sites that endorse hatred and violence towards the United States and its allies by sharing their hatred and actively promoting their ideologies online. This research examined the source of the message, the message content, the types of receivers intended, the channels used to communicate the message, the purpose of the message, and the effects of the message. Results indicate that a major purpose of the organizations is to justify their actions to skeptics. The organizations have built a virtual extremist community with each other and outside members where their sum is greater than their total. The actual impact of these sites is difficult to measure. However, while Web 2.0 features are employed on these sites, this study argues that censorship and forum rules restrict members from engaging in a real dialogue thus limiting the potential of recruiting moderates