The onset of convection in horizontally partitioned porous layers

In this paper, the onset of convection in a horizontally partitioned porous layer is investigated. Two identical sublayers are separated by a thin impermeable barrier. There exists a background horizontal flow in one of the layers or, equivalently, flows of half that strength in each sublayer but in opposite directions. A linearised stability analysis is performed where the horizontal component of the disturbance is factored into separate Fourier modes, leaving an ordinary differential eigenvalue problem for the critical Darcy-Rayleigh number as a function of the wavenumber. The dispersion relation is derived and the neutral stability curves are obtained for a wide range of horizontal flow rates. The presence of the horizontal flow alters the morphology of the neutral curves from that which occurs when there is no flow and travelling modes may arise. We also determine the condition under which the most dangerous disturbance changes from a stationary mode to travelling mode. Some three-dimensional aspects are also considered. (C) 2011 American Institute of Physics. [doi:10.1063/1.3589864

Why Current Statistical Approaches to Ransomware Detection Fail

The frequent use of basic statistical techniques to detect ransomware is a popular and intuitive strategy; statistical tests can be used to identify randomness, which in turn can indicate the presence of encryption and, by extension, a ransomware attack. However, common file formats such as images and compressed data can look random from the perspective of some of these tests. In this work, we investigate the current frequent use of statistical tests in the context of ransomware detection, primarily focusing on false positive rates. The main aim of our work is to show that the current over-dependence on simple statistical tests within anti-ransomware tools can cause serious issues with the reliability and consistency of ransomware detection in the form of frequent false classifications. We determined thresholds for five key statistics frequently used in detecting randomness, namely Shannon entropy, chi-square, arithmetic mean, Monte Carlo estimation for Pi and serial correlation coefficient. We obtained a large data set of 84,327 files comprising of images, compressed data and encrypted data. We then tested these thresholds (taken from a variety of previous publications in the literature where possible) against our dataset, showing that the rate of false positives is far beyond what could be considered acceptable. False positive rates were often above 50% and even above 90% on several occasions. False negative rates were also generally between 5% and 20%, numbers which are also far too high. As a direct result of these experiments, we determine that relying on these simple statistical approaches is not good enough to detect ransomware attacks consistently. We instead recommend the exploration of higher-order statistics such as skewness and kurtosis for future ransomware detection techniques

Recurrence of Pancreatic Neuroendocrine Tumors and Survival Predicted by Ki67

Background: Despite evidence of different malignant potentials, postoperative follow-up assessment is similar for G1 and G2 pancreatic neuroendocrine tumors (panNETs) and adjuvant treatment currently is not indicated. This study investigated the role of Ki67 with regard to recurrence and survival after curative resection of panNET. Methods: Patients with resected non-functioning panNET diagnosed between 1992 and 2016 from three institutions were retrospectively analyzed. Patients who had G1 or G2 tumor without distant metastases or hereditary syndromes were included in the study. The patients were re-categorized into Ki67 0–5 and Ki67 6–20%. Cox regression analysis with log-rank testing for recurrence and survival was performed. Results: The study enrolled 241 patients (86%) with Ki67 0–5% and 39 patients (14%) with Ki67 6–20%. Recurrence was seen in 34 patients (14%) with Ki67 0–5% after a median period of 34 months and in 16 patients (41%) with Ki67 6–20% after a median period of 16 months (p < 0.001). The 5-year recurrence-free and 10-year disease-specific survival periods were respectively 90 and 91% for Ki67 0–5% and respectively 55 and 26% for Ki67 6–20% (p < 0.001). The overall survival period after recurrence was 44.9 months, which was comparable between the two groups (p = 0.283). In addition to a Ki67 rate higher than 5%, tumor larger than 4 cm and lymph node metastases were independently associated with recurrence. Conclusions: Patients at high risk for recurrence after curative resection of G1 or G2 panNET can be identified by a Ki67 rate higher than 5%. These patients should be more closely monitored postoperatively to detect recurrence early and might benefit from adjuvant treatment. A clear postoperative follow-up regimen is proposed

Numerical simulations of swirling pipe flows- decay of swirl and occurrence of vortex structures

The present work aims at better understanding of the physics underlying swirling flows in pipes by means of numerical simulations. Direct numerical simulations have been carried out by using two different inlet swirl conditions. In one case, rotating honeycomb is used as the means to generate swirl whereas in the other case a solid body rotation is provided at the inlet. The inlet swirl intensity is varied in order to scan the underlying physics. Reynolds number 1730 is selected so that the flow remains in laminar regime. The results are compared with those obtained from the experiments using a similar experimental set-up. It is shown that the increase in the inlet swirl intensity leads to a faster decay of swirl downstream of the pipe. Similarly certain specific vortex structures are observed in the radial velocity contours. These structures are thought to be analogous with those found in the Taylor-Couette flow between a stationary outer cylinder and inner rotating cone. The reported investigations reveal dependence of swirl decay on the inlet swirl intensity and occurrence of vortex structures

Evaluation of three instrumentation techniques at the precision of apical stop and apical sealing of obturation

OBJECTIVE: The aim of this study was to investigate the ability of two NiTi rotary apical preparation techniques used with an electronic apex locator-integrated endodontic motor and a manual technique to create an apical stop at a predetermined level (0.5 mm short of the apical foramen) in teeth with disrupted apical constriction, and to evaluate microleakage following obturation in such prepared teeth. MATERIAL AND METHODS: 85 intact human mandibular permanent incisors with single root canal were accessed and the apical constriction was disrupted using a #25 K-file. The teeth were embedded in alginate and instrumented to #40 using rotary Lightspeed or S-Apex techniques or stainless-steel K-files. Distance between the apical foramen and the created apical stop was measured to an accuracy of 0.01 mm. In another set of instrumented teeth, root canals were obturated using gutta-percha and sealer, and leakage was tested at 1 week and 3 months using a fluid filtration device. RESULTS: All techniques performed slightly short of the predetermined level. Closest preparation to the predetermined level was with the manual technique and the farthest was with S-Apex. A significant difference was found between the performances of these two techniques (

Imagination, Hope and the Migrant Journey : Iraqi Asylum Seekers Looking for a Future in Europe

Europe received an unprecedented number of asylum seekers in 2015. This article examines Iraqi asylum seekers who journeyed through Europe in search of an idealized version of Finland, which they had imagined based on word-of-mouth and social media information. Through cognitive migration, the act of pre-experiencing futures in different locations, Finland was seen to offer both subjective hope of personal growth and advancement and objective hope of safety and physical security. This hope motivated them to embark on a journey of 6,000 kilometers to the European North. Based on interview data and relevant studies, the article concludes that hope of a better, imagined future abroad acts as a powerful magnet for persons with poor prospects in their countries of origin. Hope is a kind of critical emotion strongly shaped by beliefs and real-time opportunities; and as such, beliefs are notoriously difficult to change. Imagination, therefore, should not be overlooked when planning and implementing migration policies.Europe received an unprecedented number of asylum seekers in 2015. This article examines Iraqi asylum seekers who journeyed through Europe in search of an idealized version of Finland, which they had imagined based on word-of-mouth and social media information. Through cognitive migration, the act of pre-experiencing futures in different locations, Finland was seen to offer both subjective hope of personal growth and advancement and objective hope of safety and physical security. This hope motivated them to embark on a journey of 6,000 kilometers to the European North. Based on interview data and relevant studies, the article concludes that hope of a better, imagined future abroad acts as a powerful magnet for persons with poor prospects in their countries of origin. Hope is a kind of critical emotion strongly shaped by beliefs and real-time opportunities; and as such, beliefs are notoriously difficult to change. Imagination, therefore, should not be overlooked when planning and implementing migration policies.Peer reviewe

Next Generation Cryptographic Ransomware

We are assisting at an evolution in the ecosystem of cryptoware - the malware that encrypts files and makes them unavailable unless the victim pays up. New variants are taking the place once dominated by older versions; incident reports suggest that forthcoming ransomware will be more sophisticated, disruptive, and targeted. Can we anticipate how such future generations of ransomware will work in order to start planning on how to stop them? We argue that among them there will be some which will try to defeat current anti-ransomware; thus, we can speculate over their working principle by studying the weak points in the strategies that seven of the most advanced anti-ransomware are currently implementing. We support our speculations with experiments, proving at the same time that those weak points are in fact vulnerabilities and that the future ransomware that we have imagined can be effective

Activated Human CD4+CD45RO+ Memory T-Cells Indirectly Inhibit NLRP3 Inflammasome Activation through Downregulation of P2X7R Signalling

Inflammasomes are multi-protein complexes that control the production of pro-inflammatory cytokines such as IL-1β. Inflammasomes play an important role in the control of immunity to tumors and infections, and also in autoimmune diseases, but the mechanisms controlling the activation of human inflammasomes are largely unknown. We found that human activated CD4+CD45RO+ memory T-cells specifically suppress P2X7R-mediated NLRP3 inflammasome activation, without affecting P2X7R-independent NLRP3 or NLRP1 inflammasome activation. The concomitant increase in pro-IL-1β production induced by activated memory T-cells concealed this effect. Priming with IFNβ decreased pro-IL-1β production in addition to NLRP3 inflammasome inhibition and thus unmasked the inhibitory effect on NLRP3 inflammasome activation. IFNβ suppresses NLRP3 inflammasome activation through an indirect mechanism involving decreased P2X7R signaling. The inhibition of pro-IL-1β production and suppression of NLRP3 inflammasome activation by IFNβ-primed human CD4+CD45RO+ memory T-cells is partly mediated by soluble FasL and is associated with down-regulated P2X7R mRNA expression and reduced response to ATP in monocytes. CD4+CD45RO+ memory T-cells from multiple sclerosis (MS) patients showed a reduced ability to suppress NLRP3 inflammasome activation, however their suppressive ability was recovered following in vivo treatment with IFNβ. Thus, our data demonstrate that human P2X7R-mediated NLRP3 inflammasome activation is regulated by activated CD4+CD45RO+ memory T cells, and provide new information on the mechanisms mediating the therapeutic effects of IFNβ in MS

Metabolism-dependent bioaccumulation of uranium by Rhodosporidium toruloides isolated from the flooding water of a former uranium mine

Remediation of former uranium mining sites represents one of the biggest challenges worldwide that have to be solved in this century. During the last years, the search of alternative strategies involving environmentally sustainable treatments has started. Bioremediation, the use of microorganisms to clean up polluted sites in the environment, is considered one the best alternative. By means of culture-dependent methods, we isolated an indigenous yeast strain, KS5 (Rhodosporidium toruloides), directly from the flooding water of a former uranium mining site and investigated its interactions with uranium. Our results highlight distinct adaptive mechanisms towards high uranium concentrations on the one hand, and complex interaction mechanisms on the other. The cells of the strain KS5 exhibit high a uranium tolerance, being able to grow at 6 mM, and also a high ability to accumulate this radionuclide (350 mg uranium/g dry biomass, 48 h). The removal of uranium by KS5 displays a temperature- and cell viability-dependent process, indicating that metabolic activity could be involved. By STEM (scanning transmission electron microscopy) investigations, we observed that uranium was removed by two mechanisms, active bioaccumulation and inactive biosorption. This study highlights the potential of KS5 as a representative of indigenous species within the flooding water of a former uranium mine, which may play a key role in bioremediation of uranium contaminated sites.This work was supported by the Bundesministerium für Bildung und Forschung grand nº 02NUK030F (TransAqua). Further support took place by the ERDF-co-financed Grants CGL2012-36505 and 315 CGL2014-59616R, Ministerio de Ciencia e Innovación, Spain