A comparison of forensic toolkits and mass market data recovery applications

Digital forensic application suites are large, expensive, complex software products, offering a range of functions to assist in the investigation of digital artifacts. Several authors have raised concerns as to the reliability of evidence derived from these products. This is of particular concern, given that many forensic suites are closed source and therefore can only be subject to black box evaluation. In addition, many of the individual functions integrated into forensic suites are available as commercial stand-alone products, typically at a much lower cost, or even free. This paper reports research which compared (rather than individually evaluated) the data recovery function of two forensic suites and three stand alone `non-forensic' commercial applications. The research demonstrates that, for this function at least, the commercial data recovery tools provide comparable performance to that of the forensic software suites. In addition, the research demonstrates that there is some variation in results presented by all of the data recovery tools

A comparison of incompressible limits for resistive plasmas

The constraint of incompressibility is often used to simplify the magnetohydrodynamic (MHD) description of linearized plasma dynamics because it does not affect the ideal MHD marginal stability point. In this paper two methods for introducing incompressibility are compared in a cylindrical plasma model: In the first method, the limit $\gamma \to \infty$ is taken, where $\gamma$ is the ratio of specific heats; in the second, an anisotropic mass tensor $\mathbf{\rho}$ is used, with the component parallel to the magnetic field taken to vanish, $\rho_{\parallel} \to 0$. Use of resistive MHD reveals the nature of these two limits because the Alfv\'en and slow magnetosonic continua of ideal MHD are converted to point spectra and moved into the complex plane. Both limits profoundly change the slow-magnetosonic spectrum, but only the second limit faithfully reproduces the resistive Alfv\'en spectrum and its wavemodes. In ideal MHD, the slow magnetosonic continuum degenerates to the Alfv\'en continuum in the first method, while it is moved to infinity by the second. The degeneracy in the first is broken by finite resistivity. For numerical and semi-analytical study of these models, we choose plasma equilibria which cast light on puzzling aspects of results found in earlier literature.Comment: 14 pages, 10 figure

Estimativa do nível crítico de cobre para a soja, em solos do cerrado brasileiro.

A prática da monocultura de soja no Brasil, com o passar do tempo, pode diminuir o teor de matéria orgânica dos solos, sendo esse problema mais sério em solos arenosos. Isso tem aumentado a deficiência de certos micronutrientes, em especial o cobre (Cu). Além disso, a aplicação de adubos, muitas vezes em demasia e sem critério técnico, pode provocar problemas nutricionais de toxicidade ou deficiência desse micronutriente. Com a expansão da soja nas regiões de solos de Cerrado, passou-se para o cultivo em solos de textura média a arenosa, com teores de argila inferiores a 200 g.kg-1, CTC baixa e, originalmente, com baixo teor de Cu. Foram instalados experimentos, com a cultura da soja, em três solos do Cerrado: Latossolo Vermelho Amarelo (LVA) com 260 g.kg-1 de argila, no município de Tasso Fragoso, Latossolo Vermelho (LV) com 450 g.kg-1 de argila, no município de São Raimundo das Mangabeiras, ambos no sul do Estado do Maranhão e em Latossolo Vermelho (LV) com 550 g.kg-1 de argila, no município de Pedra Preta, sudeste do Estado do Mato Grosso, com seis doses de Cu (0; 1,25; 2,5; 5,0; 10 e 20 kg/ha), da fonte sulfato de cobre (30% de Cu) e seis níveis de saturação de bases (V%=30, 40, 50, 60, 70 e 80), com quatro repetições. Os valores estimados, acima dos quais não é esperada resposta à aplicação de cobre, são de 0,74 mg.dm-3 e 0,34 mg.dm-3 de Cu2+, pelos métodos Mehlich e DTPA, respectivamente. Portanto, as faixas de Cu no solo em mg.dm-3, para interpretação dos níveis do nutriente no solo são: para o Método Mehlich-1; Baixo 0,74. Para o Método DTPA; Baixo 0,34

Bostonia. Volume 15

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Credimus

We believe that economic design and computational complexity---while already important to each other---should become even more important to each other with each passing year. But for that to happen, experts in on the one hand such areas as social choice, economics, and political science and on the other hand computational complexity will have to better understand each other's worldviews. This article, written by two complexity theorists who also work in computational social choice theory, focuses on one direction of that process by presenting a brief overview of how most computational complexity theorists view the world. Although our immediate motivation is to make the lens through which complexity theorists see the world be better understood by those in the social sciences, we also feel that even within computer science it is very important for nontheoreticians to understand how theoreticians think, just as it is equally important within computer science for theoreticians to understand how nontheoreticians think

Path Integral Monte Carlo Simulation of the Low-Density Hydrogen Plasma

Restricted path integral Monte Carlo simulations are used to calculate the equilibrium properties of hydrogen in the density and temperature range of $9.83 \times 10^{-4}\rm \leq \rho \leq 0.153 \rm gcm^{-3}$ and $5000 \leq T \leq 250 000 \rm K$. We test the accuracy of the pair density matrix and analyze the dependence on the system size, on the time step of the path integral and on the type of nodal surface. We calculate the equation of state and compare with other models for hydrogen valid in this regime. Further, we characterize the state of hydrogen and describe the changes from a plasma to an atomic and molecular liquid by analyzing the pair correlation functions and estimating the number of atoms and molecules present.Comment: 12 pages, 21 figures, submitted for Phys. Rev.

Membrane shape as a reporter for applied forces

Recent advances have enabled 3-dimensional reconstructions of biological structures in vivo, ranging in size and complexity from single proteins to multicellular structures. In particular, tomography and confocal microscopy have been exploited to capture detailed 3-dimensional conformations of membranes in cellular processes ranging from viral budding and organelle maintenance to phagocytosis. Despite the wealth of membrane structures available, there is as yet no generic, quantitative method for their interpretation. We propose that by modeling these observed biomembrane shapes as fluid lipid bilayers in mechanical equilibrium, the externally applied forces as well as the pressure, tension, and spontaneous curvature can be computed directly from the shape alone. To illustrate the potential power of this technique, we apply an axial force with optical tweezers to vesicles and explicitly demonstrate that the applied force is equal to the force computed from the membrane conformation

Formation and Interaction of Membrane Tubes

We show that the formation of membrane tubes (or membrane tethers), which is a crucial step in many biological processes, is highly non-trivial and involves first order shape transitions. The force exerted by an emerging tube is a non-monotonic function of its length. We point out that tubes attract each other, which eventually leads to their coalescence. We also show that detached tubes behave like semiflexible filaments with a rather short persistence length. We suggest that these properties play an important role in the formation and structure of tubular organelles.Comment: 4 pages, 3 figure

Solution-Phase Combinatorial Chemistry in Lead Discovery

Solution-phase approaches in combinatorial chemistry complement solid-phase approaches and each can be used to advantage in particular circumstances. Solution-phase synthesis of pools of compounds, whilst allowing successful identification of a selection of good lead structures for medicinal chemistry programmes, also reinforced a number of the disadvantages of such an approach. Solution-phase parallel synthesis of discrete compounds has, however, proved to be a very useful and popular approach both for lead generation and in lead optimisation work. The range of chemistry suitable for use in such approaches is expanding rapidly and some of these chemistries are discussed. The current focus is on enhancing the quality of compounds prepared in array formats, and we describe a number of useful approaches which are being developed to that end