2,255 research outputs found

    Morphology of the nonspherically decaying radiation generated by a rotating superluminal source: reply to comment

    Full text link
    The fact that the formula used by Hannay in his Comment is "from a standard text on electrodynamics" neither warrants that it is universally applicable, nor that it is unequivocally correct. We have explicitly shown [J. Opt. Soc. Am. A 25, 543 (2008)] that,since it does not include the boundary contribution toward the value of the field, the formula in question is not applicable when the source is extended and has a distribution pattern that rotates faster than light in vacuo. The neglected boundary term in the retarded solution to the wave equation governing the electromagnetic field forms the basis of diffraction theory. If this term were identically zero, for the reasons given by Hannay, the iffraction of electromagnetic waves through apertures on a surface enclosing a source would have been impossible. If this term were identically zero, for the reasons given by Hannay, the diffraction of electromagnetic waves through apertures on a surface enclosing a source would have been impossible

    Winding number correlation for a Brownian loop in a plane

    Get PDF
    A Brownian loop is a random walk circuit of infinitely many, suitably infinitesimal, steps. In a plane such a loop may or may not enclose a marked point, the origin, say. If it does so it may wind arbitrarily many times, positive or negative, around that point. Indeed from the (long known) probability distribution, the mean square winding number is infinite, so all statistical moments - averages of powers of the winding number - are infinity (even powers) or zero (odd powers, by symmetry). If an additional marked point is introduced at some distance from the origin, there are now two winding numbers, which are correlated. That correlation, the average of the product of the two winding numbers, is finite and is calculated here. The result takes the form of a single well-convergent integral that depends on a single parameter - the suitably scaled separation of the marked points. The integrals of the correlation weighted by powers of the separation are simple factorial expressions. Explicit limits of the correlation for small and large separation of the marked points are found.Comment: The right hand sides of various equations were missing factors of 1/2 or 1/4, now correcte

    The zombies strike back: Towards client-side beef detection

    Get PDF
    A web browser is an application that comes bundled with every consumer operating system, including both desktop and mobile platforms. A modern web browser is complex software that has access to system-level features, includes various plugins and requires the availability of an Internet connection. Like any multifaceted software products, web browsers are prone to numerous vulnerabilities. Exploitation of these vulnerabilities can result in destructive consequences ranging from identity theft to network infrastructure damage. BeEF, the Browser Exploitation Framework, allows taking advantage of these vulnerabilities to launch a diverse range of readily available attacks from within the browser context. Existing defensive approaches aimed at hardening network perimeters and detecting common threats based on traffic analysis have not been found successful in the context of BeEF detection. This paper presents a proof-of-concept approach to BeEF detection in its own operating environment – the web browser – based on global context monitoring, abstract syntax tree fingerprinting and real-time network traffic analysis

    GeoIntelligence: Data Mining Locational Social Media Content for Profiling and Information Gathering

    Get PDF
    The current social media landscape has resulted in a situation where people are encouraged to share a greater amount of information about their day-to-day lives than ever before. In this environment a large amount of personal data is disclosed in a public forum with little to no regard for the potential privacy impacts. This paper focuses on the presence of geographic data within images, metadata and individual postings. The GeoIntelligence project aims to aggregate this information to educate users on the possible implications of the utilisation of these services as well as providing service to law enforcement and business. This paper demonstrates the ability to profile users on an individual and group basis from data posted openly to social networking services

    The impace of custom ROM backups on android external storage erasure

    Get PDF
    The Android operating system is the current market leader on mobile devices such as smartphones and tablet computers. The core operating system is open source and has a number of developers creating variants of this operating system. These variants, often referred to as custom ROMs are available for a wide number of mobile devices. Custom ROMs provide a number of features, such as enhanced control over the operating system, variation in user interfaces and so on. The process of installing custom ROMs is often accomplished through the use of a ROM manager application. Such applications often provide mechanisms to back up the contents of the mobile device prior to upgrade. This mechanism is utilised in the case of a failed update to restore the device to its previous functional state. Backups produced in this manner are often stored in on an external media such as a micro-SD card.In the conducted research we evaluated devices inbuilt data erasure mechanisms within the context of erasure of backups produced by ROM managers. It was found that simply using the devices Format External / SD function is not an effective means of completely erasing these backups. Once recovered, these backups offer a quick source of information that a potential attacker could carve to retrieve user files such as media transferred to the external or from applications. Although the same files could be recovered from an image of the external storage itself, the carving process is more efficient than traditional carving methods

    Explaining ‘carbon’ in community sequestration projects: a key element in the creation of local carbon knowledges

    Get PDF
    The formation of local carbon knowledge is central to the meaningful participation of communities in the land-based carbon projects which have become widespread in pursuit of global emissions reductions. Through a qualitative analysis of interviews with community sensitization practitioners, this paper considers how concepts of carbon are communicated to project communities. We find that fieldworkers use people’s own experiences to make intangible carbon visible, but rely on scientific concepts to explain the transfer of carbon between states. However, interviews suggest that project communities’ knowledge and understanding of carbon is partial. This highlights the challenges of meeting the safeguarding principles of respect for local knowledge and informed consent in carbon projects. We conclude that greater attention needs to be given by planners to the role of communication in carbon projects, including the potential to draw on indigenous knowledges to advance local understanding

    A non-device specific framework for the development of forensic locational data analysis procedure for consumer grade small and embedded devices

    Get PDF
    Portable and wearable computing devices such as smart watches, navigation units, mobile phones, and tablet computers commonly ship with Global Navigation Satellite System (GNSS) supported locational awareness. Locational functionality is no longer limited to navigation specific devices such as satellite navigation devices and location tracking systems. Instead the use of these technologies has extended to become secondary functionality on many devices, including mobile phones, cameras, portable computers, and video game consoles. The increase in use of location aware technology is of use to forensic investigators as it has the potential to provide historic locational information. The evidentiary value of these devices to forensic investigators is currently limited due to the lack of available forensic tools and published methods to properly acquire and analyse these data sources. This research addresses this issue through the synthesis of common processes for the development of forensic procedure to acquire and interpret historic locational data from embedded, locationally aware devices. The research undertaken provides a framework for the generation of forensic procedure to enable the forensic extraction of historical locational data. The framework is device agnostic, relying instead on differential analysis and structured testing to produce a validated method for the extraction of locational history. This framework was evaluated against five devices, selected on a basis of market penetration, availability and a stage of deduplication. The examination of the framework took place in a laboratory developed specifically for the research. This laboratory replicates all identified sources of location data for the devices selected. In this case the laboratory is able to simulate cellular (2G and 3G), GNSS (NAVSTAR and GLONASS), and Wi-Fi locationing services. The laboratory is a closed-sky facility, meaning that the laboratory is contained within a faraday cage and all signals are produced and broadcast internally. Each selected device was run through a series of simulations. These simulations involved the broadcast of signals, replicating the travel of a specific path. Control data was established through the use of appropriate data recording systems, for each of the simulated location signals. On completion of the simulation, each device was forensically acquired and analysed in accordance with the proposed framework. For each experiment carried out against the five devices, the control and experimental data were compared. In this examination any divergence less than those expected for GNSS were ignored. Any divergence greater than this was examined to establish cause. Predictable divergence was accepted and non-predictable divergence would have been noted as a limitation. In all instances where data was recovered, all divergences were found to be predictable. Post analysis, the research found that the proposed framework was successful in producing locational forensic procedure in a non-device specific manner. This success was confirmed for all the devices tested

    Kindle Forensics: Acquisition & Analysis

    Get PDF
    The Amazon Kindle eBook reader supports a wide range of capabilities beyond reading books. This functionality includes an inbuilt cellular data connection known as Whispernet. The Kindle provides web browsing, an application framework, eBook delivery and other services over this connection. The historic data left by user interaction with this device may be of forensic interest. Analysis of the Amazon Kindle device has resulted in a method to reliably extract and interpret data from these devices in a forensically complete manner. Keywords: forensics, digital forensics, kindle, mobile, embedded, ebook, ereade
    • …