5,183 research outputs found
Dynamic Analysis of Executables to Detect and Characterize Malware
It is needed to ensure the integrity of systems that process sensitive
information and control many aspects of everyday life. We examine the use of
machine learning algorithms to detect malware using the system calls generated
by executables-alleviating attempts at obfuscation as the behavior is monitored
rather than the bytes of an executable. We examine several machine learning
techniques for detecting malware including random forests, deep learning
techniques, and liquid state machines. The experiments examine the effects of
concept drift on each algorithm to understand how well the algorithms
generalize to novel malware samples by testing them on data that was collected
after the training data. The results suggest that each of the examined machine
learning algorithms is a viable solution to detect malware-achieving between
90% and 95% class-averaged accuracy (CAA). In real-world scenarios, the
performance evaluation on an operational network may not match the performance
achieved in training. Namely, the CAA may be about the same, but the values for
precision and recall over the malware can change significantly. We structure
experiments to highlight these caveats and offer insights into expected
performance in operational environments. In addition, we use the induced models
to gain a better understanding about what differentiates the malware samples
from the goodware, which can further be used as a forensics tool to understand
what the malware (or goodware) was doing to provide directions for
investigation and remediation.Comment: 9 pages, 6 Tables, 4 Figure
Application of Situational Leadership to the National Voluntary Public Health Accreditation Process
Successful navigation through the accreditation process developed by the Public Health Accreditation Board (PHAB) requires strong and effective leadership. Situational leadership, a contingency theory of leadership, frequently taught in the public health classroom, has utility for leading a public health agency through this process. As a public health agency pursues accreditation, staff members progress from being uncertain and unfamiliar with the process to being knowledgeable and confident in their ability to fulfill the accreditation requirements. Situational leadership provides a framework that allows leaders to match their leadership styles to the needs of agency personnel. In this paper, the application of situational leadership to accreditation is demonstrated by tracking the process at a progressive Kentucky county public health agency that served as a PHAB beta test site
Activation of mesangial cell MAPK in responseto homocysteine
Activation of mesangial cell MAPK in response to homocysteine.BackgroundAlteration in mesangial cell function is central to the progression of glomerular disease in numerous models of chronic renal failure (CRF). Animal models of chronic glomerular disease are characterized by mesangial cell proliferation and elaboration of extracellular matrix protein (ECM), resulting in glomerulosclerosis. Elevated plasma levels of homocysteine (Hcy) are seen in both animal models and humans with CRF, and have been proposed to contribute to the high prevalence of vascular disease in this group. Some of the pathogenetic effects of Hcy are thought to be mediated via the induction of endoplasmic reticulum stress. Thus, Hcy effects on mesangial cells could contribute to the progression of CRF. Previous work has shown Hcy- mediated induction of Erk mitogen-activated protein kinase (MAPK) in vascular smooth muscle cells (VSMCs). Erk induces increases in activator protein-1 (AP-1) transcription factor activity which may augment mesangial cell proliferation and ECM protein production. Consequently, we studied the effect of Hcy on mesangial cell Erk signaling.MethodsMesangial cells were exposed to Hcy after 24 hours of serum starvation and Erk activity assessed. Nuclear translocation of phospho-Erk was visualized by confocal microscopy. AP-1 nuclear protein binding was measured in response to Hcy by mobility shift assay. Hcy-induced mesangial cell calcium flux was measured in Fura-2 loaded cells. Mesangial cell DNA synthesis in response to Hcy was assessed by [3H]-thymidine incorporation and proliferation by Western blotting for proliferating cell nuclear antigen (PCNA). Expression of endoplasmic reticulum stress response genes were determined by Northern and Western analysis.ResultsHcy led to an increase in Erk activity that was maximal at 50 ÎŒmol/L and 20 minutes of treatment. Subsequent experiments used this concentration and time point. Erk activity in response to Hcy was insensitive to n-acetylcysteine and catalase, indicating oxidative stress did not play a role. However, Hcy50 ÎŒmol/L induced a brief increase in intracellular mesangial cell calcium within 5 minutes, and the calcium ionophores A23187 and ionomycin increased Erk activity while chelation of intracellular calcium with BAPTA-AM abrogated the Erk response to Hcy. Confocal microscopy of activated Erk nuclear translocation mirrored these results as did mesangial cell nuclear protein binding to AP-1 consensus sequences. Hcy- induced increases in thymidine incorporation and PCNA expression at 24 hours were Erk dependent. The expression of endoplasmic reticulum stress response genes was significantly elevated by Hcy in an Erk-dependent manner.ConclusionHcy increases Erk activity in mesangial cells via a calcium-dependent mechanism, resulting in increased AP-1 nuclear protein binding, cell DNA synthesis and proliferation and induction of endoplasmic reticulum stress. These observations suggest potential mechanisms by which Hcy may contribute to progressive glomerular injury
On the eigenvalues of Cayley graphs on the symmetric group generated by a complete multipartite set of transpositions
Given a finite simple graph \cG with vertices, we can construct the
Cayley graph on the symmetric group generated by the edges of \cG,
interpreted as transpositions. We show that, if \cG is complete multipartite,
the eigenvalues of the Laplacian of \Cay(\cG) have a simple expression in
terms of the irreducible characters of transpositions, and of the
Littlewood-Richardson coefficients. As a consequence we can prove that the
Laplacians of \cG and of \Cay(\cG) have the same first nontrivial
eigenvalue. This is equivalent to saying that Aldous's conjecture, asserting
that the random walk and the interchange process have the same spectral gap,
holds for complete multipartite graphs.Comment: 29 pages. Includes modification which appear on the published version
in J. Algebraic Combi
Nature tourism and Irish film
This article provides a historical overview and reading of seminal Irish film from the perspective of nature tourism. Within Irish cultural studies, tourism is frequently equated with an overly romantic image of the island, which has been used to sell the country abroad. However, using notions like the tourist gaze and taking on board influential debates around space/place, one can posit a more progressive environmental vision of nature and landscape in our readings of film
Present-day stress orientations and tectonic provinces of the NW Borneo collisional margin
Extent: 15p.Borehole failure observed on image and dipmeter logs from 55 petroleum wells across the NW Borneo collisional margin were used to determine maximum horizontal stress (ÏH) orientations; combined with seismic and outcrop data, they define seven tectonic provinces. The Baram DeltaâDeepwater Fold-Thrust Belt exhibits three tectonic provinces: its inner shelf inverted province (ÏH is NW-SE, margin-normal), its outer shelf extension province (ÏH is NE-SW, margin-parallel), and its slope to basin floor compression province (ÏH is NW-SE, margin-normal). In the inverted province, ÏH reflects inversion of deltaic normal faults. The ÏH orientations in the extension and compression provinces reflect deltaic gravitational tectonics. The shale and minibasin provinces have been recognized in offshore Sabah. In the shale province, ÏH is N010°E, which aligns around the boundary of a massif of mobile shale. Currently, no data are available to determine ÏH in the minibasin province. In the Balingian province, ÏH is ESE-WNW, reflecting ESE absolute Sunda plate motions due to the absence of a thick detachment seen elsewhere in NW Borneo. The Central Luconia province demonstrates poorly constrained and variable ÏH orientations. These seven provinces result from the heterogeneous structural and stratigraphic development of the NW Borneo margin and formed due to complex collisional tectonics and the varied distribution and thicknesses of stratigraphic packages.Rosalind C. King, Mark R. P. Tingay, Richard R. Hillis, Christopher K. Morley, and James Clar
Agriculture, food security and climate change: Outlook for knowledge, tools and action
Agriculture and food security are key sectors for intervention under climate change. Agricultural production is highly vulnerable even to 2C (lowend) predictions for global mean temperatures in 2100, with major implications for rural poverty and for both rural and urban food security. Agriculture also presents untapped opportunities for mitigation, given the large land area under crops and rangeland, and the additional mitigation potential of aquaculture. This paper presents a summary of current scientific knowledge on the impacts of climate change on farming and food systems, and on the implications for adaptation and mitigation. Many of the trends and impacts are highly uncertain at a range of spatial and temporal scales; we need significant advances in predicting how climate variability and change will affect future food security. Despite these uncertainties, it is clear that the magnitude and rate of projected changes will require adaptation. Actions towards adaptation fall into two broad overlapping areas: (1) better management of agricultural risks associated with increasing climate variability and extreme events, for example improved climate information services and safety nets, and (2) accelerated adaptation to progressive climate change over decadal time scales, for example integrated packages of technology, agronomy and policy options for farmers and food systems. Maximization of agricultureâs mitigation potential will require, among others, investments in technological innovation and agricultural intensification linked to increased efficiency of inputs, and creation of incentives and monitoring systems that are inclusive of smallholder farmers. The challenges posed by climate change to agriculture and food security require a holistic and strategic approach to linking knowledge with action. Key elements of this are greater interactions between decision-makers and researchers in all sectors, greater collaboration among climate, agriculture and food security communities, and consideration of interdependencies across whole food systems and landscapes. Food systems faced with climate change need urgent action in spite of uncertainties
Photodetachment study of the 1s3s4s ^4S resonance in He^-
A Feshbach resonance associated with the 1s3s4s ^{4}S state of He^{-} has
been observed in the He(1s2s ^{3}S) + e^- (\epsilon s) partial photodetachment
cross section. The residual He(1s2s ^{3}S) atoms were resonantly ionized and
the resulting He^+ ions were detected in the presence of a small background. A
collinear laser-ion beam apparatus was used to attain both high resolution and
sensitivity. We measured a resonance energy E_r = 2.959 255(7) eV and a width
\Gamma = 0.19(3) meV, in agreement with a recent calculation.Comment: LaTeX article, 4 pages, 3 figures, 21 reference
Investigation of the Proteolytic Functions of an Expanded Cercarial Elastase Gene Family in Schistosoma mansoni
Schistosome parasites are a major cause of disease in the developing world. The larval stage of the parasite transitions between an intermediate snail host and a definitive human host in a dramatic fashion, burrowing out of the snail and subsequently penetrating human skin. This process is facilitated by secreted proteases. In Schistosoma mansoni, cercarial elastase is the predominant secreted protease and essential for host skin invasion. Genomic analysis reveals a greatly expanded cercarial elastase gene family in S. mansoni. Despite sequence divergence, SmCE isoforms show similar expression profiles throughout the S. mansoni life cycle and have largely similar substrate specificities, suggesting that the majority of protease isoforms are functionally redundant and therefore their expansion is an example of gene dosage. However, activity-based profiling also indicates that a subset of SmCE isoforms are activated prior to the parasite's exit from its intermediate snail host, suggesting that the protease may also have a role in this process
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