Physical Layer Network Coding for Two-Way Relaying with QAM

The design of modulation schemes for the physical layer network-coded two way relaying scenario was studied in [1], [3], [4] and [5]. In [7] it was shown that every network coding map that satisfies the exclusive law is representable by a Latin Square and conversely, and this relationship can be used to get the network coding maps satisfying the exclusive law. But, only the scenario in which the end nodes use $M$-PSK signal sets is addressed in [7] and [8]. In this paper, we address the case in which the end nodes use $M$-QAM signal sets. In a fading scenario, for certain channel conditions $\gamma e^{j \theta}$, termed singular fade states, the MA phase performance is greatly reduced. By formulating a procedure for finding the exact number of singular fade states for QAM, we show that square QAM signal sets give lesser number of singular fade states compared to PSK signal sets. This results in superior performance of $M$-QAM over $M$-PSK. It is shown that the criterion for partitioning the complex plane, for the purpose of using a particular network code for a particular fade state, is different from that used for $M$-PSK. Using a modified criterion, we describe a procedure to analytically partition the complex plane representing the channel condition. We show that when $M$-QAM ($M >4$) signal set is used, the conventional XOR network mapping fails to remove the ill effects of $\gamma e^{j \theta}=1$, which is a singular fade state for all signal sets of arbitrary size. We show that a doubly block circulant Latin Square removes this singular fade state for $M$-QAM.Comment: 13 pages, 14 figures, submitted to IEEE Trans. Wireless Communications. arXiv admin note: substantial text overlap with arXiv:1203.326

Rarefaction Effects on Thermal Transport and Flow Structures in Cavity Flows

Accurate simulation and modeling the effects of rarefaction on heat and mass transport is of much interest in high-speed flow applications including hypersonic vehicles and atmospheric re-entry flights. Toward this end, the present work develops numerical schemes appropriate for a wide range of Knudsen numbers and performs analytical investigation of the rarefaction effects. First, the Unified Gas Kinetic Scheme (UGKS) is extended to a wider range of Mach and Knudsen numbers by implementing WENO (Weighted Essentially Non-Oscillatory) interpolation. Direct Simulation Monte Carlo (DSMC) computations are also performed when appropriate for comparison purposes. Though DSMC method is theoretically valid in the entire range of Knudsen numbers (from continuum to free-molecular), real computations with DSMC are limited to rarefied flows as this method demands excessive computational resources to simulate continuum/near-continuum flows. The effect of rarefaction is examined in the canonical lid-driven flows. In particular, the effect of cavity size (cavity aspect ratio), flow speed (lid Mach number) and degree of rarefaction (global Knudsen number) on flow structures and transport properties in the cavity are examined. The simulations are performed at a wide range of flow regimes (a) subsonic incompressible, subsonic compressible and supersonic (b) Knudsen numbers: continuum, near-continuum, transition and highly rarefied regimes. Flow (vortex) structures and thermal transport are characterized as functions of different flow regimes and cavity size. Mechanism of vortex evolution is investigated at a microscopic perspective. Parametric studies followed by careful observations and rigorous analyses reveal important insights to the rarefaction effects on the heat and mass transport behavior of canonical 2D cavity flows. The proposed scheme can extensively be used for fluid flows comprising of large density variations whose length scales extend from a macroscale to a molecular scale

Una nueva especie de Parasopubia (Orobanchaceae) del sur de las Ghats occidentales, India

Parasopubia raghavendrae, a new species of Orobanchaceae is described from the southern Western Ghats of Kerala. It resembles P. delphinifolia and P. hofmannii var. hofmannii by its habit, shape, colour and hairiness of corolla lobes but differs by length of calyx tube, hairiness of staminal filaments and stomium, and shape and ornamentation of seeds. Parasopubia raghavendrae is hitherto known only from the type locality Mathikettan Shola National Park in Idukki district, Kerala. Detailed description of the new species along with colour photographs and comparison with its closely similar species are given. We also assessed provisionally the conservation status of the new species as Critically Endangered (CR) according to IUCN Red List Categories and Criteria.Parasopubia raghavendrae, una nueva especie de Orobanchaceae se describe para el sur del Ghats occidental de Kerala. Se asemeja a P. delphinifolia y P. hofmannii var. hofmannii por su hábito, forma, color e indumento de los lóbulos de la corola, y difiere de ellas por la longitud del tubo del cáliz, indumento del filamento estaminal y del estomio, y la forma y ornamentación de las semillas. Hasta ahora, P. raghavendrae solo se conoce para la localidad tipo del Parque Nacional de Mathikettan Shola, en el distrito de Idukki, Kerala. Se proporciona la descripción detallada de la nueva especie junto con fotografías en color y una comparativa con las especies más similares. Así mismo, se evalúa provisionalmente el estado de conservación de la nueva especie con la categoría en Peligro Crítico (CR) de acuerdo a los Criterios de la Lista Roja de la UICN

A Novel Framework For Detecting Subdomain State Against Takeover Attacks

The Domain Name System (DNS) oversees the internet's architecture, providing pointers to both internal and external services. Consequently, enterprises increase their attack surface while simultaneously increasing their exposure to potential cyber threats. Subdomain takeovers happen when a subdomain leads to a website that no longer exists. As a result, the subdomain will be in control of an attacker. A compromised subdomain may be the access point to many attacks like information threats, phishing attacks, infrastructure intrusion and many more. Subdomain takeover attacks are one of the overlooked attack surfaces related to cyber security. This thesis aims to investigate the subdomain takeover attacks, how the attacks happen, the attack methodology by an attacker and drawbacks in the current strategies and tools, which are countermeasures for subdomain takeover attacks. The research focuses on resolving an intrusion from happening within the perspective of an enterprise standpoint. A new custom framework which resolves the subdomain takeover attacks was developed. A comparative study of the newly developed framework and the existing open-source tools and their response to an attack scenario too is made. Also, a comparison of the leading cloud platforms was conducted and their existing security features and mitigation measures for similar attacks and threats

A Novel Framework For Detecting Subdomain State Against Takeover Attacks

The Domain Name System (DNS) oversees the internet's architecture, providing pointers to both internal and external services. Consequently, enterprises increase their attack surface while simultaneously increasing their exposure to potential cyber threats. Subdomain takeovers happen when a subdomain leads to a website that no longer exists. As a result, the subdomain will be in control of an attacker. A compromised subdomain may be the access point to many attacks like information threats, phishing attacks, infrastructure intrusion and many more. Subdomain takeover attacks are one of the overlooked attack surfaces related to cyber security. This thesis aims to investigate the subdomain takeover attacks, how the attacks happen, the attack methodology by an attacker and drawbacks in the current strategies and tools, which are countermeasures for subdomain takeover attacks. The research focuses on resolving an intrusion from happening within the perspective of an enterprise standpoint. A new custom framework which resolves the subdomain takeover attacks was developed. A comparative study of the newly developed framework and the existing open-source tools and their response to an attack scenario too is made. Also, a comparison of the leading cloud platforms was conducted and their existing security features and mitigation measures for similar attacks and threats

Modelling how responsiveness to interferon improves interferon-free treatment of hepatitis C virus infection

Direct-acting antiviral agents (DAAs) for hepatitis C treatment tend to fare better in individuals who are also likely to respond well to interferon-alpha (IFN), a surprising correlation given that DAAs target specific viral proteins whereas IFN triggers a generic antiviral immune response. Here, we posit a causal relationship between IFN-responsiveness and DAA treatment outcome. IFN-responsiveness restricts viral replication, which would prevent the growth of viral variants resistant to DAAs and improve treatment outcome. To test this hypothesis, we developed a multiscale mathematical model integrating IFN-responsiveness at the cellular level, viral kinetics and evolution leading to drug resistance at the individual level, and treatment outcome at the population level. Model predictions quantitatively captured data from over 50 clinical trials demonstrating poorer response to DAAs in previous non-responders to IFN than treatment-naïve individuals, presenting strong evidence supporting the hypothesis. Model predictions additionally described several unexplained clinical observations, viz., the percentages of infected individuals who 1) spontaneously clear HCV, 2) get chronically infected but respond to IFN-based therapy, and 3) fail IFN-based therapy but respond to DAA-based therapy, resulting in a comprehensive understanding of HCV infection and treatment. An implication of the causal relationship is that failure of DAA-based treatments may be averted by adding IFN, a strategy of potential use in settings with limited access to DAAs. A second, wider implication is that individuals with greater IFN-responsiveness would require shorter DAA-based treatment durations, presenting a basis and a promising population for response-guided therapy