206 research outputs found

    Information Hiding with Data Diffusion Using Convolutional Encoding for Super-Encryption

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    The unification of data encryption with information hiding methods continues to receive significant attention because of the importance of protecting encrypted information by making it covert. This is because one of the principal limitations in any cryptographic system is that encrypted data flags the potential importance of the data (i.e. the plaintext information that has been encrypted) possibly leading to the launch of an attack which may or may not be successful. Information hiding overcomes this limitation by making the data (which may be the plaintext or the encrypted plaintext) imperceptible, the security of the hidden information being compromised if and only if its existence is detected. We consider two functions f1(r) and f2(r) for r ∈ R n , n = 1, 2, 3, ... and the problem of ‘Diffusing’ these functions together, applying a process we call ‘Stochastic Diffusion’ to the diffused field and then hiding the output of this process into one of the two functions. The coupling of these two processes using a form of conditioning that generates a well-posed inverse solution yields a super-encrypted field that is dataconsistent. After presenting the basic encryption method and (encrypted) information hiding model coupled with a mathematical analysis (within the context of ‘convolutional encoding’), we provide a case study which is concerned with the implementation of the approach for full-colour 24-bit digital images. The ideas considered yields the foundations for a number of wide-ranging applications that include covert signal and image information interchange, data authentication, copyright protection and digital rights management. In this context, we also provide prototype software using m-code and Python for readers to use, improve upon and develop further for applications of interest

    Status of the Dorcas gazelle (Gazella dorcas) in the area south of Green Mountain, Libya in 2007: challenges and opportunities for the future

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    Threats to Dorcas gazelle were examined and the rate of decrease in population was estimated in the area south of the Green Mountain in North-East Libya. The results were collected from questionnaires and focal interviews. All previous studies had reported significant decreased in Dorcas gazelle population throughout Libya during the last years of the twentieth century. The results showed that Dorcas gazelle continues to exist but in very low numbers. The number of groups of gazelle has decreased and the estimated rate of decline has increased to between 60 and 90 % in 2007. The decline has been noticeable with typical herd sizes of approximately 50 – 100 gazelle being reported before 1970, 10 – 15 gazelle seen in the 1970s, 5 – 10 gazelle in the 1980s and from the 1990s onwards, group sizes of only 3 or fewer gazelles. Shared use of habitat with domestic sheep and predators does not appear to be detrimental to Dorcas gazelle, but the main threat for this animal is humans, who lack awareness of its natural value. Some respondents believed that Dorcas gazelle had left their habitat and migrated to other safe areas, but this study showed that the number of Dorcas gazelle was decreasing rapidly, mainly because of overhunting. Further research is needed into the current distribution and numbers of surviving Dorcas gazelle. Aerial and ground surveys of areas of potential habitat should be carried out to establish the current status and distribution. There is an urgent need for the implementation of management programme to conserve the gazelle involving the participation of local people

    The use of immobilized microalgal bead concentrations in the removal of ammonium nitrogen from synthetic wastewater

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    Removal of chemical pollutants has been important in the treatment of wastewater. The effect of Chlorella vulgaris (microalgae) on the removal of ammonium nitrogen (NH4+) in synthetic wastewater (wastewater prepared in the laboratory) was investigated. C. vulgaris cells were immobilized in calcium alginate beads to allow diffusion of nutrients but retention of the cells. Concentration of C. vulgaris cells used to treat wastewater were equivalent to 20 g/l, 40 g/l and 80 g/l of wastewater and treatment was under laboratory conditions at 25±2°C. C. vulgaris was effective in the removal of NH4+ from wastewater; at  the end of 24 hours of treatment, there was reduction in the initial concentration of NH4+ by 78% for 20 g/l. For 40 g/l treatment, there was 97% reduction in NH4+ and 91% reduction for 80 g/l treatment. After 43 hr of treatment, there was further reduction in NH4+ for 20 g/l (86%), and 80 g/l (93%) but 40 g/l (97%) remained constant. The concentration of C. vulgaris that showed the best activity in removing NH4+ -from wastewater was 40 g/l.Keywords: Microalgae, immobilize, microalgae, bead concentrations, ammonium nitroge

    A pan-cancer analysis of the frequency of DNA alterations across cell cycle activity levels

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    Pan-cancer genomic analyses based on the magnitude of pathway activity are currently lacking. Focusing on the cell cycle, we examined the DNA mutations and chromosome arm-level aneuploidy within tumours with low, intermediate and high cell-cycle activity in 9515 pan-cancer patients with 32 different tumour types. Boxplots showed that cell-cycle activity varied broadly across and within all cancers. TP53 and PIK3CA mutations were common in all cell cycle score (CCS) tertiles but with increasing frequency as cell-cycle activity levels increased (P < 0.001). Mutations in BRAF and gains in 16p were less frequent in CCS High tumours (P < 0.001). In Kaplan–Meier analysis, patients whose tumours were CCS Low had a longer Progression Free Interval (PFI) relative to Intermediate or High (P < 0.001) and this significance remained in multivariable analysis (CCS Intermediate: HR = 1.37; 95% CI 1.17–1.60, CCS High: 1.54; 1.29–1.84, CCS Low = Ref). These results demonstrate that whilst similar DNA alterations can be found at all cell-cycle activity levels, some notable exceptions exist. Moreover, independent prognostic information can be derived on a pan-cancer level from a simple measure of cell-cycle activity

    Separation of breast cancer and organ microenvironment transcriptomes in metastases

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    Background: The seed and soil hypothesis was proposed over a century ago to describe why cancer cells (seeds) grow in certain organs (soil). Since then, the genetic properties that define the cancer cells have been heavily investigated; however, genomic mediators within the organ microenvironment that mediate successful metastatic growth are less understood. These studies sought to identify cancer- and organ-specific genomic programs that mediate metastasis. Methods: In these studies, a set of 14 human breast cancer patient-derived xenograft (PDX) metastasis models was developed and then tested for metastatic tropism with two approaches: spontaneous metastases from mammary tumors and intravenous injection of PDX cells. The transcriptomes of the cancer cells when growing as tumors or metastases were separated from the transcriptomes of the microenvironment via species-specific separation of the genomes. Drug treatment of PDX spheroids was performed to determine if genes activated in metastases may identify targetable mediators of viability. Results: The experimental approaches that generated metastases in PDX models were identified. RNA sequencing of 134 tumors, metastases, and normal non-metastatic organs identified cancer- and organ-specific genomic properties that mediated metastasis. A common genomic response of the liver microenvironment was found to occur in reaction to the invading PDX cells. Genes within the cancer cells were found to be either transiently regulated by the microenvironment or permanently altered due to clonal selection of metastatic sublines. Gene Set Enrichment Analyses identified more than 400 gene signatures that were commonly activated in metastases across basal-like PDXs. A Src signaling signature was found to be extensively upregulated in metastases, and Src inhibitors were found to be cytotoxic to PDX spheroids. Conclusions: These studies identified that during the growth of breast cancer metastases, there were genomic changes that occurred within both the cancer cells and the organ microenvironment. We hypothesize that pathways upregulated in metastases are mediators of viability and that simultaneously targeting changes within different cancer cell pathways and/or different tissue compartments may be needed for inhibition of disease progression

    Nonequilibrium relaxation in neutral BCS superconductors: Ginzburg-Landau approach with Landau damping in real time

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    We present a field-theoretical method to obtain consistently the equations of motion for small amplitude fluctuations of the order parameter directly in real time for a homogeneous, neutral BCS superconductor. This method allows to study the nonequilibrium relaxation of the order parameter as an initial value problem. We obtain the Ward identities and the effective actions for small phase the amplitude fluctuations to one-loop order. Focusing on the long-wavelength, low-frequency limit near the critical point, we obtain the time-dependent Ginzburg-Landau effective action to one-loop order, which is nonlocal as a consequence of Landau damping. The nonequilibrium relaxation of the phase and amplitude fluctuations is studied directly in real time. The long-wavelength phase fluctuation (Bogoliubov-Anderson-Goldstone mode) is overdamped by Landau damping and the relaxation time scale diverges at the critical point, revealing critical slowing down.Comment: 31 pages 14 figs, revised version, to appear in Phys. Rev.

    The impact of low-frequency and rare variants on lipid levels

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    Using a genome-wide screen of 9.6 million genetic variants achieved through 1000 Genomes Project imputation in 62,166 samples, we identify association to lipid traits in 93 loci, including 79 previously identified loci with new lead SNPs and 10 new loci, 15 loci with a low-frequency lead SNP and 10 loci with a missense lead SNP, and 2 loci with an accumulation of rare variants. In six loci, SNPs with established function in lipid genetics (CELSR2, GCKR, LIPC and APOE) or candidate missense mutations with predicted damaging function (CD300LG and TM6SF2) explained the locus associations. The low-frequency variants increased the proportion of variance explained, particularly for low-density lipoprotein cholesterol and total cholesterol. Altogether, our results highlight the impact of low-frequency variants in complex traits and show that imputation offers a cost-effective alternative to resequencing

    Discovery and fine-mapping of glycaemic and obesity-related trait loci using high-density imputation

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    Reference panels from the 1000 Genomes (1000G) Project Consortium provide near complete coverage of common and low-frequency genetic variation with minor allele frequency &ge;0.5% across European ancestry populations. Within the European Network for Genetic and Genomic Epidemiology (ENGAGE) Consortium, we have undertaken the first large-scale meta-analysis of genome-wide association studies (GWAS), supplemented by 1000G imputation, for four quantitative glycaemic and obesity-related traits, in up to 87,048 individuals of European ancestry. We identified two loci for body mass index (BMI) at genome-wide significance, and two for fasting glucose (FG), none of which has been previously reported in larger meta-analysis efforts to combine GWAS of European ancestry. Through conditional analysis, we also detected multiple distinct signals of association mapping to established loci for waist-hip ratio adjusted for BMI (RSPO3) and FG (GCK and G6PC2). The index variant for one association signal at the G6PC2 locus is a low-frequency coding allele, H177Y, which has recently been demonstrated to have a functional role in glucose regulation. Fine-mapping analyses revealed that the non-coding variants most likely to drive association signals at established and novel loci were enriched for overlap with enhancer elements, which for FG mapped to promoter and transcription factor binding sites in pancreatic islets, in particular. Our study demonstrates that 1000G imputation and genetic fine-mapping of common and low-frequency variant association signals at GWAS loci, integrated with genomic annotation in relevant tissues, can provide insight into the functional and regulatory mechanisms through which their effects on glycaemic and obesity-related traits are mediated

    Petrophysical, Geochemical, and Hydrological Evidence for Extensive Fracture-Mediated Fluid and Heat Transport in the Alpine Fault's Hanging-Wall Damage Zone

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    Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging-wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP-2). We present observational evidence for extensive fracturing and high hanging-wall hydraulic conductivity (∼10−9 to 10−7 m/s, corresponding to permeability of ∼10−16 to 10−14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP-2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging-wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off-fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation
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