OS diversity for intrusion tolerance: Myth or reality?

One of the key benefits of using intrusion-tolerant systems is the possibility of ensuring correct behavior in the presence of attacks and intrusions. These security gains are directly dependent on the components exhibiting failure diversity. To what extent failure diversity is observed in practical deployment depends on how diverse are the components that constitute the system. In this paper we present a study with operating systems (OS) vulnerability data from the NIST National Vulnerability Database. We have analyzed the vulnerabilities of 11 different OSes over a period of roughly 15 years, to check how many of these vulnerabilities occur in more than one OS. We found this number to be low for several combinations of OSes. Hence, our analysis provides a strong indication that building a system with diverse OSes may be a useful technique to improve its intrusion tolerance capabilities

Minimally Extended Left-Right Symmetric Model for Dark Matter with U(1) Portal

A minimal extension of the left-right symmetric model for neutrino masses that includes a vector-like singlet fermion dark matter (DM) is presented with the DM connected to the visible sector via a gauged U(1) portal. We discuss the symmetry breaking in this model and calculate the mass and mixings of the extra heavy neutral gauge boson at the TeV scale. The extra gauge boson can decay to both standard model particles as well to dark matter. We calculate the relic density of the singlet fermion dark matter and its direct detection cross section and use these constraints to obtain the allowed parameter range for the new gauge coupling and the dark matter mass.Comment: 19 pages, 8 figure

INJECTABLE HYBRID SYSTEM FOR STRONTIUM LOCAL DELIVERY TO PROMOTE BONE REGENERATION

In bone tissue regeneration strategies, injectable bone substitutes are very attractive since they can be applied with minimally invasive surgical procedures and can perfectly fill irregular defects created in cases of trauma, infection or tumor resection. These materials must combine adequate mechanical properties with the ability to induce new bone formation. Incorporating strontium (Sr) in bone substitute biomaterials may be a strategy to achieve high Sr concentrations, not in a systemic but in a local environment, taking advantage of the osteoanabolic and anti-osteoclastic activity of Sr, for the enhancement of new bone formation. In this context, the aim of the present work was to evaluate the response of a Sr-hybrid injectable system for bone regeneration, designed by our group, consisting of hydroxyapatite microspheres doped with Sr and an alginate vehicle crosslinked in situ with Sr, in an in vivo scenario. Two different animal models were used, rat (Wistar) and sheep (Merino Branco) critical sized bone defect. Non Sr-doped similar materials (Ca-hybrid) or empty defects were used as control. Sr-hybrid system led to an increased bone formation in both center and periphery of a rat critical sized defect compared to a non Sr–doped similar system, where new bone formation was restricted to the periphery. Moreover newly formed bone was identified as early as one week after its implantation in a sheep model. After eight weeks, the bone surrounded the microspheres, both in the periphery and in the center of the defect. Most importantly, the hybrid system provided a scaffold for cell migration and tissue ingrowth and offered structural support, as observed in both models. The effective improvement of local bone formation suggests that this might be a promising approach for bone regeneration, especially in osteoporotic conditions

Is the distribution of Amblyomma variegatum influenced by interspecific competition with Amblyomma hebraeum? Preliminary study: distribution range in Mozambique

Widely spread in intertropical and subtropical areas of Africa, the southern distribution of Amblyomma variegatum in Mozambique seems to have its limit around the Save River, at the 22nd parallel South. This area also corresponds to the northern limit of another Amblyomma tick, A. hebraeum. Several authors use to explain the absence of A. variegatum more southwards by an interspecific competition with A. hebraeum. Whereas only A. variegatum is known to favor dermatophilosis, a skin disease that can cause important burden in ruminants, both species are good vectors of Ehrlichia ruminantium, the bacteria causing heartwater, a fatal disease of ruminants representing a major constraint for livestock development in Africa. However, their vector competence may be different and vary according to the strain of E. ruminantium. As a result, the bio-ecology and distribution of those vectors in the field may result in specific epidemiological patterns for the diseases they transmit and are important to understand to adopt proper sanitary control and prevention measures. Little information on current (last decade) Amblyomma distribution in Mozambique is available, and little is known on the factors influencing their distribution. More especially, the existence of a distribution overlap, as observed in Zimbabwe is not known in Mozambique. Indeed the extent of this overlap and the distribution of A. variegatum and A. hebraeum in this particular area represent useful information to assess potential interspecific competition. The objective of this study is to assess the current distribution of A. variegatum and A. hebraeum in this country and to better locate and characterize species limitation ranges around the Save River with a view to further identify the factors influencing their distribution. First, an exhaustive literature review was made to collect all published and unpublished data relating to the distribution of A. variegatum and A. hebraeum in Africa. A field entomological survey was then conducted in Mozambique between February and April 2012 to identify ticks collected on cattle, in the Inhambane, Manica and Sofala provinces, nearby the Save River. Sampling sites included dip-tanks and corridors, used for acaricides treatment by neighboring farmers, as well as farms which were selected by the local Veterinary Service. In each study site, about 60 animals were carefully examined for ticks presence and abundance, mostly in corridors and on 10 laid-down animals most heavily infested by ticks. Ticks, males and females, were collected to confirm species identification. Data on domestic ruminant population and movements as well as breeding practices including tick control were also collected through interviews with farmers and local and central veterinary services. The epidemiological unit is the sampling site. A site was considered positive for a given tick species if at least one animal was infested by at least one tick of that species, otherwise, it was considered negative. To better assess species presence in their limit of distribution, an attempt was made to interpret presence and absence data to distinguish well-established or occasionally present population and likely not detected or absent populations. This was done considering sampling method, tick abundance, study period against phenology, as well as other information: last acaricide treatment, animal introduction, etc. Data were entered in Access database and displayed on a Geographic Information System, ArcMap9.3 A map of the current A. variegatum and A. hebraeum distribution was produced and included 103 positive sites out of 113 sampled between 2000 and 2012. The field survey conducted in 30 study sites evidenced a distribution overlap of 30km (western side) to 100km (eastern side) width, along a slanting line northwest-southeast accross the Save River, where both species were found in three sites and coinfestation of few animals was observed. The current distribution o

Análise exploratória de dados de monitoramento dos animais em um sistema de integração lavoura-pecuária.

Resumo: A aplicação dos preceitos da Agricultura de Precisão em um sistema de Integração Lavoura-Pecuária (ILP) envolve um grau de dificuldade maior devido ao número de fatores envolvidos e a presença da componente animal. Variáveis como a mobilidade, pisoteio, dejeções dos animais e zonas preferenciais podem impactar o sistema e devem ser consideradas. O objetivo deste trabalho é realizar uma análise exploratória dos dados de monitoramento de animais em um sistema ILP. Os dados foram obtidos por aparelhos GPS afixados em animais do rebanho e complementados por observações de campo. São apresentados mapas derivados da aplicação do estimador de intensidade Kernel para situações distintas e levantadas hipóteses sobre os comportamentos dos animais

NIR spectroscopy of the Sun and HD20010 - Compiling a new linelist in the NIR

Context: Effective temperature, surface gravity, and metallicity are basic spectroscopic stellar parameters necessary to characterize a star or a planetary system. Reliable atmospheric parameters for FGK stars have been obtained mostly from methods that relay on high resolution and high signal-to-noise optical spectroscopy. The advent of a new generation of high resolution near-IR spectrographs opens the possibility of using classic spectroscopic methods with high resolution and high signal-to-noise in the NIR spectral window. Aims: We aim to compile a new iron line list in the NIR from a solar spectrum to derive precise stellar atmospheric parameters, comparable to the ones already obtained from high resolution optical spectra. The spectral range covers 10 000 {\AA} to 25 000 {\AA}, which is equivalent to the Y, J, H, and K bands. Methods: Our spectroscopic analysis is based on the iron excitation and ionization balance done in LTE. We use a high resolution and high signal-to-noise ratio spectrum of the Sun from the Kitt Peak telescope as a starting point to compile the iron line list. The oscillator strengths (log gf) of the iron lines were calibrated for the Sun. The abundance analysis was done using the MOOG code after measuring equivalent widths of 357 solar iron lines. Results: We successfully derived stellar atmospheric parameters for the Sun. Furthermore, we analysed HD20010, a F8IV star, from which we derived stellar atmospheric parameters using the same line list as for the Sun. The spectrum was obtained from the CRIRES- POP database. The results are compatible with the ones found in the literature, confirming the reliability of our line list. However, due to the quality of the data we obtain large errors.Comment: 9 pages and 9 figure

Modified Gravity on the Brane and Dark Energy

We analyze the dynamics of an AdS5 braneworld with matter fields when gravity is allowed to deviate from the Einstein form on the brane. We consider exact 5-dimensional warped solutions which are associated with conformal bulk fields of weight -4 and describe on the brane the following three dynamics: those of inhomogeneous dust, of generalized dark radiation, and of homogeneous polytropic dark energy. We show that, with modified gravity on the brane, the existence of such dynamical geometries requires the presence of non-conformal matter fields confined to the brane.Comment: Revised version published in Gen. Rel. Grav. Typos corrected, updated reference and some remarks added for clarity. 11 pages, latex, no figure