WorldWideScience

Sample records for angle of attack

  1. Effect of attack angle on flow characteristic of centrifugal fan

    Science.gov (United States)

    Wu, Y.; Dou, H. S.; Wei, Y. K.; Chen, X. P.; Chen, Y. N.; Cao, W. B.

    2016-05-01

    In this paper, numerical simulation is performed for the performance and internal flow of a centrifugal fan with different operating conditions using steady three-dimensional incompressible Navier-Stokes equations coupled with the RNG k-e turbulent model. The performance curves, the contours of static pressure, total pressure, radial velocity, relative streamlines and turbulence intensity at different attack angles are obtained. The distributions of static pressure and velocity on suction surface and pressure surface in the same impeller channel are compared for various attack angles. The research shows that the efficiency of the centrifugal fan is the highest when the attack angle is 8 degree. The main reason is that the vortex flow in the impeller is reduced, and the jet-wake pattern is weakened at the impeller outlet. The pressure difference between pressure side and suction side is smooth and the amplitude of the total pressure fluctuation is low along the circumferential direction. These phenomena may cause the loss reduced for the attack angle of about 8 degree.

  2. Non-linear Flight Dynamics at High Angles of Attack

    DEFF Research Database (Denmark)

    Granasy, P.; Sørensen, C.B.; Mosekilde, Erik; Thomasson, P.G.

    1998-01-01

    The methods of nonlinear dynamics are applied to the longitudinal motion of a vectored thrust aircraft, in particular the behavior at high angles of attack. Our model contains analytic nonlinear aerodynamical coefficients based on NASA windtunnel experiments on the F-18 high-alpha research vehicle...

  3. Non-linear Flight Dynamics at High Angles of Attack

    DEFF Research Database (Denmark)

    Granasy, P.; Sørensen, C.B.; Mosekilde, Erik;

    1998-01-01

    The methods of nonlinear dynamics are applied to the longitudinal motion of a vectored thrust aircraft, in particular the behavior at high angles of attack. Our model contains analytic nonlinear aerodynamical coefficients based on NASA windtunnel experiments on the F-18 high-alpha research vehicl...

  4. Yaw Control At High Angles Of Attack

    Science.gov (United States)

    Murri, Daniel G.; Rao, Dhanvada M.

    1988-01-01

    Hinged, conformal forebody strakes provide control when rudders become ineffective. Device consists of symmetric pair of longitudinally hinged strakes designed to fold completely into forebody contour. Strakes rotate individually out into external flow. Asymmetric flow produced by deployed strake generates sideward force causing aircraft to yaw.

  5. High angle of attack aerodynamics subsonic, transonic, and supersonic flows

    CERN Document Server

    Rom, Josef

    1992-01-01

    The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist...

  6. Determination of the angle of attack on rotor blades

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Hansen, Martin Otto Laver; Sørensen, Jens Nørkær

    2009-01-01

    Two simple methods for determining the angle of attack (AOA) on a section of a rotor blade are proposed. Both techniques consist of employing the Biot-Savart integral to determine the influence of the bound vorticity on the velocity field. In the first technique, the force distribution along the...... techniques. The advantage of the proposed techniques, as compared with existing techniques, is that they can be used to determine the AOA on rotor blades under general flow conditions (e.g. operations in yaw or with dynamic inflow)....

  7. Potential flow past axisymmetric bodies at angle of attack

    Science.gov (United States)

    Kuhlman, J. M.; Shu, J.-Y.

    1984-01-01

    The Karamcheti (1966) suggestion concerning the use of higher order singularity techniques has been developed for the calculation of incompressible flow past an axisymmetric body at angle of attack. Attention is given to the results of a convergence study using this axial singularity method, where solution accuracy has been investigated for ellipsoids of slenderness ratio in the 1-10 range for both axial and inclined flow. Effects of singularity type, element number and size distribution, and singularity line inset distance, are noted, and a paneling scheme is developed which yields accurate results for the class of axisymmetric bodies having continuous body slopes with discontinuous curvature jumps.

  8. Review of Research On Angle-of-Attack Indicator Effectiveness

    Science.gov (United States)

    Le Vie, Lisa R.

    2014-01-01

    The National Aeronautics and Space Administration (NASA) conducted a literature review to determine the potential benefits of a display of angle-of-attack (AoA) on the flight deck of commercial transport that may aid a pilot in energy state awareness, upset recovery, and/or diagnosis of air data system failure. This literature review encompassed an exhaustive list of references available and includes studies on the benefits of displaying AoA information during all phases of flight. It also contains information and descriptions about various AoA indicators such as dial, vertical and horizontal types as well as AoA displays on the primary flight display and the head up display. Any training given on the use of an AoA indicator during the research studies or experiments is also included for review

  9. CFD Analysis on Airfoil at High Angles of Attack

    Directory of Open Access Journals (Sweden)

    Dr.P.PrabhakaraRao, Sri Sampath.V

    2014-07-01

    Full Text Available The present work describes a conceptual study of performance enhancing devices for an airfoil by using Computational Fluid Dynamics. Two simple passive devices are selected and examined for Lift improvement and for decrease in Drag. The motivation behind this project is to study these effective techniques to improve performance with fewer drawbacks then previously existing model. The effective position for the location of Dimples and Cylinder are found out. Among the two selected models, Dimple model shows good results compare to other. The CAD model is prepared in CATIA V5 R19, pre-processing is done in ANSYS ICEM CFD 14.0 and simulations are carried out in ANSYS FLUENT 14.0. The overall aim of the project is to improve airfoil performance at high angle-of-attack. The results justify the optimum position for placing Dimple and cylinder for enhancing airfoil performance.

  10. Effect of attack angle change on hydrodynamic character of supercavitating bodies

    Institute of Scientific and Technical Information of China (English)

    JIANG Zeng-hui; YU Kai-ping; WANG Cong; ZHANG Jia-zhong; HUANG Wen-hu

    2009-01-01

    A series of experiments has been done in a moderate-velocity cavitation tunnel to investigate the effects of attack angle change on hydrodynamic characters of supercavitation. Hydrodynamic characters of the aft section at various attack angles were compared. The investigation shows that hydrodynamic forces of the aft section are dependent of supercavity shapes at different attack angles, and the magnitude of hydrodynamic forces of the aft section varies with the change of attack angle. When the aft section is in the fully wetted case, the drag coefficient changes little. Lift and moment coefficients both increase with the increased attack angle, and the increase magnitude is not large. When the aft body planing is on the cavity boundary, the drag coefficient of nonzero attack angle is larger than that of zero attack angle, and the maximal lift and moment coefficients both vary obviously with the increased attack angle. In the case that the body is fully enveloped by cavity, the drag coefficient, lift coefficient and moment coefficient are nearly constant with the change of attack angles.

  11. Aerodynamic characteristics of general aviation at high angle of attack with the propeller slipstream

    Science.gov (United States)

    Matsuo, N.; Hirano, S.

    1986-01-01

    The aerodynamic characteristics of the FA-300 business aircraft at high angle of attack with the propeller stream are described. The FA-300 offers two types, FA-300-700 for 340 HP, and -710 for 450 Hp of the engine. The effects of the propeller slipstream on the high angle of the attack are discussed.

  12. EFFECT OF SWEEP ANGLE ON THE VORTICAL FLOW OVER DELTA WINGS AT AN ANGLE OF ATTACK OF 10°

    Directory of Open Access Journals (Sweden)

    JAMES BRETT

    2014-12-01

    Full Text Available CFD simulations have been used to analyse the vortical flows over sharp edged delta wings with differing sweep angles under subsonic conditions at an angle of attack of 10°. RANS simulations were validated against experimental data for a 65° sweep wing, with a flat cross-section, and the steadiness of the flow field was assessed by comparing the results against unsteady URANS and DES simulations. To assess the effect of sweep angle on the flow field, a range of sweep angles from 65° to 43° were simulated. For moderate sweep wings the primary vortex was observed to detach from the leading edge, undergoing vortex breakdown, and a weaker, replacement, "shadow" vortex was formed. The shadow vortex was observed for sweep angles of 50° and less, and resulted in reduced lift production near the wing tips loss of the stronger primary vortex.

  13. Effects of Angle of Attack and Velocity on Trailing Edge Noise

    Science.gov (United States)

    Hutcheson, Florence V.; Brooks, Thomas F.

    2006-01-01

    Trailing edge (TE) noise measurements for a NACA 63-215 airfoil model are presented, providing benchmark experimental data for a cambered airfoil. The effects of flow Mach number and angle of attack of the airfoil model with different TE bluntnesses are shown. Far-field noise spectra and directivity are obtained using a directional microphone array. Standard and diagonal removal beamforming techniques are evaluated employing tailored weighting functions for quantitatively accounting for the distributed line character of TE noise. Diagonal removal processing is used for the primary database as it successfully removes noise contaminates. Some TE noise predictions are reported to help interpret the data, with respect to flow speed, angle of attack, and TE bluntness on spectral shape and peak levels. Important findings include the validation of a TE noise directivity function for different airfoil angles of attack and the demonstration of the importance of the directivity function s convective amplification terms.

  14. Delayed detached eddy simulations of fighter aircraft at high angle of attack

    Science.gov (United States)

    Xu, Guoliang; Jiang, Xiong; Liu, Gang

    2016-08-01

    The massively separated flows over a realistic aircraft configuration at 40°, 50°, and 60° angles of attack are studied using the delayed detached eddy simulation (DDES). The calculations are carried out at experimental conditions corresponding to a mean aerodynamic chord-based Reynolds number of 8.93× 105 and Mach number of 0.088. The influence of the grid size is investigated using two grids, 20.0× 106 cells and 31.0× 106 cells. At the selected conditions, the lift, drag, and pitching moment from DDES predictions agree with the experimental data better than that from the Reynolds-averaged Navier-Stokes. The effect of angle of attack on the flow structure over the general aircraft is also studied, and it is found that the dominated frequency associated with the vortex shedding process decreases with increasing angle of attack.

  15. Surface pressure model for simple delta wings at high angles of attack

    Indian Academy of Sciences (India)

    A A Pashilkar

    2001-12-01

    A new aerodynamic modelling approach is proposed for the longitudinal static characteristics of a simple delta wing. It captures the static variation of normal force and pitching moment characteristics throughout the angle of attack range. The pressure model is based on parametrizing the surface pressure distribution on a simple delta wing. The model is then extended to a wing/body combination where body-alone data are also available. The model is shown to be simple and consistent with experimental data. The pressure model can be used as a first approximation for the load estimation on the delta wing at high angles of attack.

  16. Characterization of flow around rectangular bluff bodies at angle of attack

    International Nuclear Information System (INIS)

    Highlights: ► We describe the flow around rectangular bluff bodies at different angles of attack. ► We identify a region of angles of attack where the lift remains roughly constant. ► The constant-lift region is characterized by three-dimensional (3-D) flow. ► We develop an empirical curve fit to predict the constant-lift region. ► The empirical curve fit is valuable for modeling and simulation purposes. -- Abstract: Using data present in the literature from wind tunnel testing of semi-infinite and infinite rectangular bluff bodies at angle of attack, we develop a simple relation to predict the range of angles of attack where the lift remains approximately constant. This prediction is useful for researchers attempting to develop simplified models of the forces on rectangular bluff bodies. Additionally, prior work has shown that this region of the lift curve is characterized by complex three-dimensional flow, which has consequences for computational simulations.

  17. Parametric approximation of airfoil aerodynamic coefficients at high angles of attack

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Zahle, Frederik; Bak, Christian

    2014-01-01

    Three methods for estimating the lift and drag curves in the 360° angle of attack (α) range with harmonic approximation functions were analyzed in the present work. The first method assumes aerodynamic response of a flat plate, the second utilizes even sine and even cosine approximation functions...

  18. Numerical investigation on properties of attack angle for an opposing jet thermal protection system

    Institute of Scientific and Technical Information of China (English)

    Lu Hai-Bo; Liu Wei-Qiang

    2012-01-01

    The three-dimensional Navier Stokes equation and the k- ε viscous model are used to simulate the attack angle characteristics of a hemisphere nose-tip with an opposing jet thermal protection system in supersonic flow conditions.The numerical method is validated by the relevant experiment.The flow field parameters,aerodynamic forces,and surface heat flux distributions for attack angles of 0°,2°,5°,7°,and 10° are obtained.The detailed numerical results show that the cruise attack angle has a great inflnence on the flow field parameters,aerodynamic force,and surface heat flux distribution of the supersonic vehicle nose-tip with an opposing jet thermal protection system.When the attack angle reaches 10°,the heat flux on the windward generatrix is close to the maximal heat flux on the wall surface of the nose-tip without thermal protection system,thus the thermal protection has failed.

  19. Angle-of-attack validation of a new zonal CFD method for airfoil simulations

    Science.gov (United States)

    Yoo, Sungyul; Summa, J. Michael; Strash, Daniel J.

    1990-01-01

    The angle-of-attack validation of a new concept suggested by Summa (1990) for coupling potential and viscous flow methods has been investigated for two-dimensional airfoil simulations. The fully coupled potential/Navier-Stokes code, ZAP2D (Zonal Aerodynamics Program 2D), has been used to compute the flow field around an NACA 0012 airfoil for a range of angles of attack up to stall at a Mach number of 0.3 and a Reynolds number of 3 million. ZAP2D calculation for various domain sizes from 25 to 0.12 chord lengths are compared with the ARC2D large domain solution as well as with experimental data.

  20. Vibration Amplitude of a Flexible Filament Changes Non-Monotonically with Angle of Attack

    Science.gov (United States)

    Akaydin, H. Dogus; Voesenek, Cees J.; Lentink, David; Lentink Lab Team

    2013-11-01

    Certain animals exploit the interaction of their flexible, foil-like appendages with vortices to propel themselves effectively in surrounding fluids. The interaction is reciprocal because the fluid forces deform the appendage while the appendage alters the flow. As the flow separates from a foil-like structure, it rolls-up into a vortex with a low-pressure core, which deforms the structure until the vortex is shed into the wake. A control over this interaction can provide a robust aerodynamic performance. To identify the salient parameters that control fluid-structure interactions on a deformable structure, we varied the thickness, length and angle of attack of a rubber filament in a quasi-two-dimensional flow generated using a soap-film tunnel. We resolved fluid-structure interaction by simultaneously measuring deformation of the filament and motion of particles in the fluid using high-speed cameras. We show that increasing length or decreasing diameter of the filament increases its vibration amplitude monotonically. In stark contrast, the angle of attack of the filament may alter the amplitude of vibrations in a non-monotonic way: Within a certain range of angle of attack, the filament motion and vortex shedding lock-in, i.e. become synchronized, and result in a violent flapping behavior. This response can therefore be ceased not only by decreasing but also by increasing the angle of attack at the leading edge. Such an insight can help us engineer more effective bio-inspired robots, energy harvesters, and flow control devices with vibration control.

  1. Evaluation of electrolytic tilt sensors for measuring model angle of attack in wind tunnel tests

    Science.gov (United States)

    Wong, Douglas T.

    1992-01-01

    The results of a laboratory evaluation of electrolytic tilt sensors as potential candidates for measuring model attitude or angle of attack in wind tunnel tests are presented. The performance of eight electrolytic tilt sensors was compared with that of typical servo accelerometers used for angle-of-attack measurements. The areas evaluated included linearity, hysteresis, repeatability, temperature characteristics, roll-on-pitch interaction, sensitivity to lead-wire resistance, step response time, and rectification. Among the sensors being evaluated, the Spectron model RG-37 electrolytic tilt sensors have the highest overall accuracy in terms of linearity, hysteresis, repeatability, temperature sensitivity, and roll sensitivity. A comparison of the sensors with the servo accelerometers revealed that the accuracy of the RG-37 sensors was on the average about one order of magnitude worse. Even though a comparison indicates that the cost of each tilt sensor is about one-third the cost of each servo accelerometer, the sensors are considered unsuitable for angle-of-attack measurements. However, the potential exists for other applications such as wind tunnel wall-attitude measurements where the errors resulting from roll interaction, vibration, and response time are less and sensor temperature can be controlled.

  2. Influence of Angle of Attack and Lateral Force between Wheel and Rail on Wear of Rail--a Laboratory Study

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Angle of attack and lateral force are two important parameters influencing wheel-rail wear. This paper deals with the question of influences of the angle of attack and the lateral force on the wear of rail. A series of experiments are conducted on 1/4 JD-1 Wheel/Rail Tribology Simulation Facility. The angles of attack selected in the tests are 0°16′30″, 0°37′40″ and 1°0′0″ respectively. The lateral forces selected in the tests are 0.694 kN, 1.250 kN and 2.083 kN, respectively corresponding to the lateral forces of 25 kN, 45 kN and 75 kN measured in the field, with the aim of keeping the same ratio of L/V between laboratory and field conditions. It is found that the larger the angle of attack is, the more serious the wear of rail is. The relation of rail wear rate versus angle of attack is non-linear, and the relation of rail wear rate versus lateral force is approximately linear. The influence of angle of attack is more serious than that of lateral force. For the tractive wheelset, the wear index involving linear and quadratic function terms of angle of attack has good agreement with the limited experimental data. Some conclusions are given.

  3. Penetration and impact resistance of PDC cutters inclined at different attack angles

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to develop a rotary-percussive bit with diamond-enhanced cutters assisted by high pressure water jets,it is necessary to study the damage mechanism and the penetration properties of PDC cutters subject to different impactload level and rock types. Therefore the impact experiments of the single PDC cutters with different attack angles in fourrocks: black basalt, Missouri red granite, Halston limestone, and a very soft (Roubidoux) sandstone were carried out,and the effects of rake angles of PDC cutters on both the penetration and impact resistance of PDC cutters have been discussed in detail. Test results show that a PDC insert can withstand a very strong impact in compression but is easily damaged by impact shearing, the PDC cutters are more easily damaged by shearing if the attack angles are relatively small, the45 PDC cutters have the least penetration resistance among the cutters tested. Thus it is suggested that the attack anglesof PDC cutters should be larger than 30 for bits which must withstand impact from a hammer

  4. Effects of Sudden Changes in Inflow Conditions on the Angle of Attack on HAWT Blades

    CERN Document Server

    Stoevesandt, Bernhard

    2010-01-01

    In this paper changes in wind speed and wind direction from a measured wind field are being analyzed at high frequencies. This is used to estimate changes in the angle of attack (AOA) on a blade segment over short time periods for different estimated turbine concepts. Here a statistical approach is chosen to grasp the characteristics of the probability distributions to give an over all view of the magnitude and rate of the changes. The main interest is the generation of basic distributions for the calculation of dynamic stall effects and stall flutter due to wind fluctuations.

  5. Effects of Sudden Changes in Inflow Conditions on the Angle of Attack on HAWT Blades

    OpenAIRE

    Stoevesandt, Bernhard; Peinke, Joachim

    2010-01-01

    In this paper changes in wind speed and wind direction from a measured wind field are being analyzed at high frequencies. This is used to estimate changes in the angle of attack (AOA) on a blade segment over short time periods for different estimated turbine concepts. Here a statistical approach is chosen to grasp the characteristics of the probability distributions to give an over all view of the magnitude and rate of the changes. The main interest is the generation of basic distributions fo...

  6. A CFD Database for Airfoils and Wings at Post-Stall Angles of Attack

    Science.gov (United States)

    Petrilli, Justin; Paul, Ryan; Gopalarathnam, Ashok; Frink, Neal T.

    2013-01-01

    This paper presents selected results from an ongoing effort to develop an aerodynamic database from Reynolds-Averaged Navier-Stokes (RANS) computational analysis of airfoils and wings at stall and post-stall angles of attack. The data obtained from this effort will be used for validation and refinement of a low-order post-stall prediction method developed at NCSU, and to fill existing gaps in high angle of attack data in the literature. Such data could have potential applications in post-stall flight dynamics, helicopter aerodynamics and wind turbine aerodynamics. An overview of the NASA TetrUSS CFD package used for the RANS computational approach is presented. Detailed results for three airfoils are presented to compare their stall and post-stall behavior. The results for finite wings at stall and post-stall conditions focus on the effects of taper-ratio and sweep angle, with particular attention to whether the sectional flows can be approximated using two-dimensional flow over a stalled airfoil. While this approximation seems reasonable for unswept wings even at post-stall conditions, significant spanwise flow on stalled swept wings preclude the use of two-dimensional data to model sectional flows on swept wings. Thus, further effort is needed in low-order aerodynamic modeling of swept wings at stalled conditions.

  7. The effects of angle-of-attack indication on aircraft control in the event of an airspeed indicator malfunction

    Science.gov (United States)

    Boesser, Claas Tido

    Analysis of accident data by the Federal Aviation Administration, the National Transportation Safety Board, and other sources show that loss of control is the leading cause of aircraft accidents. Further evaluation of the data indicates that the majority of loss of control accidents are caused by the aircraft stalling. In response to these data, the Federal Aviation Administration and the General Aviation Joint Steering Committee emphasize the importance of stall and angle-of-attack awareness during flight. The high-profile crash of Air France Flight 447, in which pilots failed to recover from a self-induced stall, reinforced concerns over the need for improved stall and angle-of-attack awareness and reinvigorated interest in the debate over the effectiveness of angle-of-attack information displays. Further support for aerodynamic information in the form of an angle-of-attack indicator comes from core cognitive engineering principles. These principles argue for the provision of information about system functioning and dynamics as a means to ensure a human is always in position to recover a system when technology is unable. The purpose of this research was to empirically evaluate the importance of providing pilots with feedback about fundamental aircraft aerodynamics, especially during non-standard situations and unexpected disturbances. An experiment was conducted using a flight simulator to test the effects of in-cockpit angle-of-attack indication on aircraft control following an airspeed indicator malfunction on final approach. Participants flew a final approach with a target airspeed range of 60 to 65 knots. Once participants slowed the aircraft for final approach, the airspeed indicator needle would be stuck at an indication of 70 knots. One group of participants flew the final approach with an angle-of-attack indicator while the other group lacked such an instrument. Examination of aircraft performance data along the final approach showed that, when confronted

  8. Method for estimating the aerodynamic coefficients of wind turbine blades at high angles of attack

    Science.gov (United States)

    Beans, E. W.; Jakubowski, G. S.

    1983-12-01

    The method is based on the hypothesis that at high angles of attack the force on an airfoil is produced by the deflection of the fluid across the lower surface. It is also hypothesized that all airfoils behave the same regardless of shape and that the effects of circulation and skin friction are small. It is pointed out that the expression for the force N normal to the airfoil due to momentum exchange can be written in terms of the component parallel to the flow (drag) and the component perpendicular to the flow (lift). A comparison of estimated values with measured values and generally accepted data indicates that the method given here estimates coefficients which are low. It is thought that the difference may derive from the persistence of circulation at high angles of attack. Low estimates are not seen as a serious limitation to the designer of wind turbines. Owing to the fifth power diameter relation, the effect of a low estimate of performance on the inner portion of the blade is minimized.

  9. Application of dynamical systems theory to the high angle of attack dynamics of the F-14

    Science.gov (United States)

    Jahnke, Craig C.; Culick, Fred E. C.

    1990-01-01

    Dynamical systems theory has been used to study the nonlinear dynamics of the F-14. An eight degree of freedom model that does not include the control system present in operational F-14s has been analyzed. The aerodynamic model, supplied by NASA, includes nonlinearities as functions of the angles of attack and sideslip, the rotation rate, and the elevator deflection. A continuation method has been used to calculate the steady states of the F-14 as continuous functions of the control surface deflections. Bifurcations of these steady states have been used to predict the onset of wing rock, spiral divergence, and jump phenomena which cause the aircraft to enter a spin. A simple feedback control system was designed to eliminate the wing rock and spiral divergence instabilities. The predictions were verified with numerical simulations.

  10. Reynolds number effects on supersonic asymmetrical flows over a cone at high angle of attack

    Science.gov (United States)

    Thomas, J. L.

    1991-01-01

    The supersonic viscous flow over a 5-degree half-angle cone at an angle of attack of four times the cone half-angle is studied computationally using both the conical and the three-dimensional Navier-Stokes equations. The numerical solutions were obtained with an implicit, upwind-biased algorithm. Asymmetrical flowfields of the absolute-instability type are found using the conical-flow equations which agree with published results. However, the absolute instabilities of the originally symmetric flow found with the conical equations do not occur in the three-dimensional simulations, although spurious asymmetric three-dimensional flows for symmetric bodies arise if the grid resolution is insufficient in the nose region. The asymmetric flows computed with the three-dimensional equations are convective instabilities and are possible if the local Reynolds number exceeds a critical value and a fixed geometric asymmetry is imposed. A continuous range of asymmetries can be developed, depending on the size of the disturbance and the Reynolds number. As the Reynolds number is increased, the asymmetries demonstrate a bistable behavior at levels of side force consistent with those predicted using the conical equations. Below a certain critical Reynolds number, any flow asymmetries arising from a geometrical asymmetry are damped with increasing distance downstream from the geometrical asymmetry.

  11. High angle of attack position sensing for the Southampton University magnetic suspension and balance system

    Science.gov (United States)

    Parker, David H.

    1987-01-01

    An all digital five channel position detection system is to be installed in the Southampton University Magnetic Suspension and Balance System (SUMSBS). The system is intended to monitor a much larger range of model pitch attitudes than has been possible hitherto, up to a maximum of a 90 degree angle of attack. It is based on the use of self-scanning photodiode arrays and illuminating laser light beams, together with purpose built processing electronics. The principles behind the design of the system are discussed, together with the results of testing one channel of the system which was used to control the axial position of a magnetically suspended model in SUMSBS. The removal of optically coupled heave position information from the axial position sensing channel is described.

  12. Design of a Normal Acceleration and Angle of Attack Control System for a Missile Having Front and Rear Control Surfaces

    Science.gov (United States)

    Ochi, Yoshimasa

    Precise normal acceleration control is essential for missile guidance. Missiles with both front and rear control surfaces have a higher ability to control normal acceleration than missiles with front or rear control surfaces only. From the viewpoint of control, however, the control problem becomes a two-input-one-output problem, where generally control input cannot be determined uniquely. This paper proposes controlling angle of attack as well as normal acceleration, which makes the problem a two-input-two-output one and determines the controls uniquely. Normal acceleration command is given by a guidance system, but angle of attack command must be generated in accordance to the acceleration command without affecting the normal acceleration control. This paper also proposes such a command generator for angle of attack. Computer simulation is conducted using a nonlinear missile model to investigate the effectiveness of the control system along with control systems designed using three other methods.

  13. Effect of Varying the Angle of Attack of the Scales on a Biomimetic Shark Skin Model on Embedded Vortex Formation

    Science.gov (United States)

    Wheelus, Jennifer; Lang, Amy; Bradshaw, Michael; Jones, Emily; Afroz, Farhana; Motta, Philip; Habegger, Maria

    2012-11-01

    The skin of fast-swimming sharks is proposed to have mechanisms to reduce drag and delay flow separation. The skin of fast-swimming and agile sharks is covered with small teeth-like denticles on the order of 0.2 mm. The shortfin mako is one of the fastest and most agile ocean predators creating the need to minimize its pressure drag by controlling flow separation. Biological studies of the shortfin mako skin have shown the passive bristling angle of their denticles to exceed 50 degrees in areas on the flank corresponding to the locations likely to experience separation first. It has been shown that for an angle of attack of 90 degrees, vortices form within these cavities and impose a partial slip condition at the surface of the cavity. This experiment focuses on smaller angles of attack for denticle bristling, closer to the range thought to be achieved on real shark skin. A 3-D bristled shark skin model with varying angle of attack, embedded below a boundary layer, was used to study the formation of cavity vortices through fluorescent dye visualization and Digital Particle Image Velocimetry (DPIV). The effect of varying angle of attack on vortex formation will be discussed.

  14. Roll-Yaw control at high angle of attack by forebody tangential blowing

    Science.gov (United States)

    Pedreiro, N.; Rock, S. M.; Celik, Z. Z.; Roberts, L.

    1995-01-01

    The feasibility of using forebody tangential blowing to control the roll-yaw motion of a wind tunnel model is experimentally demonstrated. An unsteady model of the aerodynamics is developed based on the fundamental physics of the flow. Data from dynamic experiments is used to validate the aerodynamic model. A unique apparatus is designed and built that allows the wind tunnel model two degrees of freedom, roll and yaw. Dynamic experiments conducted at 45 degrees angle of attack reveal the system to be unstable. The natural motion is divergent. The aerodynamic model is incorporated into the equations of motion of the system and used for the design of closed loop control laws that make the system stable. These laws are proven through dynamic experiments in the wind tunnel using blowing as the only actuator. It is shown that asymmetric blowing is a highly non-linear effector that can be linearized by superimposing symmetric blowing. The effects of forebody tangential blowing and roll and yaw angles on the flow structure are determined through flow visualization experiments. The transient response of roll and yaw moments to a step input blowing are determined. Differences on the roll and yaw moment dependence on blowing are explained based on the physics of the phenomena.

  15. Identification of variations of angle of attack and lift coefficient for a large horizontal-axis wind turbine

    DEFF Research Database (Denmark)

    Rezaeiha, Abdolrahim; Arjomandi, Maziar; Kotsonis, Marios; Hansen, Martin Otto Laver

    2015-01-01

    the aggregate effect of elements on variations of mean value and standard deviation of the angle of attack and lift coefficient in order to distinguish the major contributing factors. The results of the current study is of paramount importance in the design of active load control systems for wind...

  16. Flow Control of the Stingray UAV at Low Angles of Attack

    Science.gov (United States)

    Farnsworth, John; Vaccaro, John; Amitay, Michael

    2007-11-01

    The effectiveness of active flow control, via synthetic jets and steady blowing jets, on the aerodynamic performance of the Stingray UAV was investigated experimentally in a wind tunnel. Global flow measurements were conducted using a six component sting balance, static pressure, and Particle Image Velocimetry (PIV) measurements. Using active control for trimming the Stingray UAV in pitch and roll at low angles of attack has similar effects to those with conventional control effectors. The synthetic jets were able to alter the local streamlines through the formation of a quasi-steady interaction region on the suction surface of the vehicle's wing. Phase locked data were acquired to provide insight into the growth, propagation, and decay of the synthetic jet impulse and its interaction with the cross-flow. The changes induced on the moments and forces can be proportionally controlled by either changing the momentum coefficient or by driving the synthetic jets with a pulse modulation waveform. This can lead the way for future development of closed-loop control models.

  17. A hybrid system approach to airspeed, angle of attack and sideslip estimation in Unmanned Aerial Vehicles

    KAUST Repository

    Shaqura, Mohammad

    2015-06-01

    Fixed wing Unmanned Aerial Vehicles (UAVs) are an increasingly common sensing platform, owing to their key advantages: speed, endurance and ability to explore remote areas. While these platforms are highly efficient, they cannot easily be equipped with air data sensors commonly found on their larger scale manned counterparts. Indeed, such sensors are bulky, expensive and severely reduce the payload capability of the UAVs. In consequence, UAV controllers (humans or autopilots) have little information on the actual mode of operation of the wing (normal, stalled, spin) which can cause catastrophic losses of control when flying in turbulent weather conditions. In this article, we propose a real-time air parameter estimation scheme that can run on commercial, low power autopilots in real-time. The computational method is based on a hybrid decomposition of the modes of operation of the UAV. A Bayesian approach is considered for estimation, in which the estimated airspeed, angle of attack and sideslip are described statistically. An implementation on a UAV is presented, and the performance and computational efficiency of this method are validated using hardware in the loop (HIL) simulation and experimental flight data and compared with classical Extended Kalman Filter estimation. Our benchmark tests shows that this method is faster than EKF by up to two orders of magnitude. © 2015 IEEE.

  18. Investigation of Strouhal number of iced cable model of cable-supported bridges with respect to angle of wind attack

    Czech Academy of Sciences Publication Activity Database

    Górski, P.; Pospíšil, Stanislav; Kuznetsov, Sergeii; Tatara, M.; Marušić, Ante

    Lublin: Polish Association for Wind Engineering, 2014 - (Lipecki, T.; Flaga, A.), s. 103-104 ISBN 978-83-932544-9-1. [International Symposium on Environmental Effects on Buildings and People /7./. Lublin - Krakow (PL), 20.10.2014-22.10.2014] R&D Projects: GA MŠk(CZ) LO1219; GA MPO(CZ) FR-TI3/654 Keywords : bridge cable * ice accretion * Strouhal number * angle of attack * vortex shedding frequency Subject RIV: JN - Civil Engineering

  19. Investigation of Strouhal numbers of iced cable models of cable-supported bridges with respect to angle of wind attack

    Czech Academy of Sciences Publication Activity Database

    Górski, P.; Tatara, M.; Pospíšil, Stanislav; Kuznetsov, Sergeii; Marušić, A.

    2015-01-01

    Roč. 112, 2-B (2015), s. 417-432. ISSN 1897-628X R&D Projects: GA MŠk(CZ) LO1219; GA MPO(CZ) FR-TI3/654 Keywords : bridge cable * ice accretion * Strouhal number * angle of attack * vortex shedding frequency Subject RIV: JN - Civil Engineering http://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i8/i4/r56684/GorskiP_InvestigationsStrouhal.pdf

  20. Experimental investigation of separated shear layer from a leading edge subjected to various angles of attack with tail flap deflections

    Indian Academy of Sciences (India)

    K Anand; S Sarkar

    2015-05-01

    Shear layer development over a thick flat plate with a semi-circular leading edge is investigated for a range of angles of attack under different pressure gradients for a Reynolds number of 2.44×105 (based on chord and free-stream velocity). The characteristics of the separated shear layer are very well documented through a combination of surface pressure measurement and smoke flow visualization. The instability of the separated layer occurs because of enhanced receptivity of perturbations leading to the development of significant unsteadiness and three-dimensional motions in the second-half of the bubble. The onset of separation, transition and the point of reattachment are identified for varying angles of attack and pressure gradients imposed by tail flap deflections. The data concerning bubble length, laminar portion and reattachment points agree well with the literature.

  1. Comparison of high-angle-of-attack slender-body theory and exact solutions for potential flow over an ellipsoid

    Science.gov (United States)

    Hemsch, Michael J.

    1990-01-01

    The accuracy of high-alpha slender-body theory (HASBT) for bodies with elliptical cross-sections is presently demonstrated by means of a comparison with exact solutions for incompressible potential flow over a wide range of ellipsoid geometries and angles of attack and sideslip. The addition of the appropriate trigonometric coefficients to the classical slender-body theory decomposition yields the formally correct HASBT, and results in accuracies previously considered unattainable.

  2. Effects of nose bluntness, roughness, and surface perturbations on the asymmetric flow past slender bodies at large angles of attack

    Science.gov (United States)

    Moskovitz, Cary A.; Dejarnette, F. R.; Hall, Robert M.

    1989-01-01

    The effects of such geometric perturbations as variations of model-tip sharpness and roughness, as well as discrete surface perturbations, on the asymmetric flow past slender bodies is experimentally investigated for the cases of a cone/cylinder model having a 10-deg semiapex angle and a 3.0-caliber tangent ogive model. Both models have base diameters of 3.5 inches, and were tested in laminar flow conditions at angles-of-attack in the 30-60 deg range. Single, discrete roughness elements were represented by beads; bead effectiveness was judged on the basis of the extent to which they affected the flowfield in various conditions.

  3. Flutter Clearance of the F-18 High-angle-of-attack Research Vehicle with Experimental Wingtip Instrumentation Pods

    Science.gov (United States)

    Freudinger, Lawrence C.

    1989-01-01

    An F-18 aircraft was modified with wingtip instrumentation pods for use in NASA's high-angle-of-attack research program. Ground vibration and flight flutter testing were performed to clear an acceptable flight envelope for the aircraft. Flight test utilized atmospheric turbulence for structural excitation; the aircraft displayed no adverse aeroelastic trends within the envelope tested. The data presented in this report include mode shapes from the ground vibration and estimates of frequency and damping as a function of Mach number.

  4. Simulator study of the effectiveness of an automatic control system designed to improve the high-angle-of-attack characteristics of a fighter airplane

    Science.gov (United States)

    Gilbert, W. P.; Nguyen, L. T.; Vangunst, R. W.

    1976-01-01

    A piloted, fixed-base simulation was conducted to study the effectiveness of some automatic control system features designed to improve the stability and control characteristics of fighter airplanes at high angles of attack. These features include an angle-of-attack limiter, a normal-acceleration limiter, an aileron-rudder interconnect, and a stability-axis yaw damper. The study was based on a current lightweight fighter prototype. The aerodynamic data used in the simulation were measured on a 0.15-scale model at low Reynolds number and low subsonic Mach number. The simulation was conducted on the Langley differential maneuvering simulator, and the evaluation involved representative combat maneuvering. Results of the investigation show the fully augmented airplane to be quite stable and maneuverable throughout the operational angle-of-attack range. The angle-of-attack/normal-acceleration limiting feature of the pitch control system is found to be a necessity to avoid angle-of-attack excursions at high angles of attack. The aileron-rudder interconnect system is shown to be very effective in making the airplane departure resistant while the stability-axis yaw damper provided improved high-angle-of-attack roll performance with a minimum of sideslip excursions.

  5. Survey of needs and capabilities for wind tunnel testing of dynamic stability of aircraft at high angles of attack

    Science.gov (United States)

    Orlik-Ruckemann, K. J.

    1973-01-01

    A survey was conducted relative to future requirements for dynamic stability information for such aerospace vehicles as the space shuttle and advanced high performance military aircraft. High-angle-of-attack and high-Reynolds number conditions were emphasized. A review was made of the wind-tunnel capabilities in North America for measuring dynamic stability derivatives, revealing an almost total lack of capabilities that could satisfy these requirements. Recommendations are made regarding equipment that should be constructed to remedy this situation. A description is given of some of the more advanced existing capabilities, which can be used to at least partly satisfy immediate demands.

  6. An Experimental Study on Aerodynamic Sound Generated from Wake Interaction of Circular Cylinder and Airfoil with Attack Angle in Tandem

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In our previous study, the effects of the interval between the cylinder and the airfoil on the aerodynamic sound were investigated and compared with the cases of single circular and single airfoil. In this study, the effects of the attack angle of the airfoil located downstream on the characteristics of aerodynamic sound and the wake structure are investigated at a given interval between the cylinder and the airfoil. It is found that the sound pressure level of DFN and the peak frequency decrease with increasing attack angle of airfoil because of the diffusive wake structure due to the increased back pressure of circular cylinder, which is caused by the blocking effect of airfoil. It is shown that the sound sources are corresponded to the attack points of shedding vortex form the upstream circular cylinder to the downstream airfoil. We conclude that the pressure fluctuation at the airfoil surface effects on the sound pressure level, from the flow visualizations and the exploration test of sound source.

  7. The Effect of Aspect Ratio and Angle of Attack on the Transition Regions of the Inverted Flag Instability

    Science.gov (United States)

    Cosse, Julia; Sader, John; Fan, Boyu; Kim, Daegyoum; Gharib, Mory

    2014-11-01

    The inverted flag instability occurs when a pliable plate is held parallel to a free-stream, with the leading edge free to move and the trailing edge clamped. Large-amplitude flapping is observed across a slim band of non-dimensional wind speeds. This specific boundaries of this flapping band vary greatly, depending on both the aspect ratio and the angle of attack of the plate with respect to the incoming flow. In addition, both periodic and aperiodic flapping modes exist. The frequency of the plate motion was analyzed and was found to be consistent with vortex-induced vibration. This research is supported by the Gordon and Betty Moore Foundation.

  8. Turbofan blade stresses induced by the flow distortion of a VTOL inlet at high angles of attack

    Science.gov (United States)

    Williams, R. C.; Diedrich, J. H.; Shaw, R. J.

    1983-01-01

    A 51-cm-diameter turbofan with a tilt-nacelle VTOL inlet was tested in the Lewis Research Center's 9- by 15-Ft Low Speed Wind Tunnel at velocities up to 72 m/s and angles of attack up to 120 deg. Fan-blade vibratory stress levels were investigated over a full aircraft operating range. These stresses were due to inlet air flow distortion resulting from (1) internal flow separation in the inlet, and (2) ingestion of the exterior nacelle wake. Stress levels are presented, along with an estimated safe operating envelope, based on infinite blade fatigue life.

  9. Vortex flow structures and interactions for the optimum thrust efficiency of a heaving airfoil at different mean angles of attack

    International Nuclear Information System (INIS)

    The thrust efficiency of a two-dimensional heaving airfoil is studied computationally for a low Reynolds number using a vortex force decomposition. The auxiliary potentials that separate the total vortex force into lift and drag (or thrust) are obtained analytically by using an elliptic airfoil. With these auxiliary potentials, the added-mass components of the lift and drag (or thrust) coefficients are also obtained analytically for any heaving motion of the airfoil and for any value of the mean angle of attack α. The contributions of the leading- and trailing-edge vortices to the thrust during their down- and up-stroke evolutions are computed quantitatively with this formulation for different dimensionless frequencies and heave amplitudes (Stc and Sta) and for several values of α. Very different types of flows, periodic, quasi-periodic, and chaotic described as Stc, Sta, and α, are varied. The optimum values of these parameters for maximum thrust efficiency are obtained and explained in terms of the interactions between the vortices and the forces exerted by them on the airfoil. As in previous numerical and experimental studies on flapping flight at low Reynolds numbers, the optimum thrust efficiency is reached for intermediate frequencies (Stc slightly smaller than one) and a heave amplitude corresponding to an advance ratio close to unity. The optimal mean angle of attack found is zero. The corresponding flow is periodic, but it becomes chaotic and with smaller average thrust efficiency as |α| becomes slightly different from zero

  10. The Biometric Values of Affected and Fellow Eyes in Patients with Acute Attack of Primary Angle Closure

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Razeghinejad

    2009-12-01

    Full Text Available Background: It has been estimated that 67 million peopleworldwide are affected with a primary glaucoma and that onethirdhave primary angle closure glaucoma. We aimed to determinethe biometric differences between the eyes of patientswith acute attack of primary angle closure and their noninvolvedfellow eyes.Methods: Twenty eight patients with acute attack of primary angleclosure were recruited in this prospective study. Three weeksafter laser iridotomy and resolution of corneal edema, all patientshad a complete ocular examination including slit lamp biomicroscopy,pachymetry, keratometry, and ocular biometry. The followingA-scan parameters were measured: anterior chamberdepth, lens thickness, axial length, lens– axial length factor, relativelens position, and corrected anterior chamber depth.Results: There were 22 (78.5% women and six (21.5% menwith mean age of 52.82±9.25 years. There were no statisticallysignificant differences in the biometric figures between theaffected and fellow eyes [anterior chamber depth (P=0.4, lensthickness (P=0.4, axial length (P=0.7, lens-axial length factor(P=0.6, relative lens position (P=0.7, and corrected anteriorchamber depth (P=0.8]. The mean ± standard deviation ofcentral corneal thickness in the affected and fellow eyes were560.12±41.93 and 557.727±18.53, respectively (P=0.806.There was no statistically significant difference between theboth eyes in the mean keratometric diopters in the affected andin the fellow eyes (45.05±2.02 v 44.91±1.73; P=0.78.Conclusion: The present study did not reveal any statisticallysignificant differences regarding the ocular biometricparameters between the affected and fellow eyes in patientswith acute primary angle closure. The biometric parameterswere similar between male and female patients as well.

  11. 1.5 μm lidar anemometer for true air speed, angle of sideslip, and angle of attack measurements on-board Piaggio P180 aircraft

    Science.gov (United States)

    Augere, B.; Besson, B.; Fleury, D.; Goular, D.; Planchat, C.; Valla, M.

    2016-05-01

    Lidar (light detection and ranging) is a well-established measurement method for the prediction of atmospheric motions through velocity measurements. Recent advances in 1.5 μm Lidars show that the technology is mature, offers great ease of use, and is reliable and compact. A 1.5 μm airborne Lidar appears to be a good candidate for airborne in-flight measurement systems. It allows measurements remotely, outside aircraft aerodynamic disturbance, and absolute air speed (no need for calibration) with great precision in all aircraft flight domains. In the framework of the EU AIM2 project, the ONERA task has consisted of developing and testing a 1.5 μm anemometer sensor for in-flight airspeed measurements. The objective of this work is to demonstrate that the 1.5 μm Lidar sensor can increase the quality of the data acquisition procedure for aircraft flight test certification. This article presents the 1.5 μm anemometer sensor dedicated to in-flight airspeed measurements and describes the flight tests performed successfully on-board the Piaggio P180 aircraft. Lidar air data have been graphically compared to the air data provided by the aircraft flight test instrumentation (FTI) in the reference frame of the Lidar sensor head. Very good agreement of true air speed (TAS) by a fraction of ms‑1, angle of sideslip (AOS), and angle of attack (AOA) by a fraction of degree were observed.

  12. Vortex flow structures and interactions for the optimum thrust efficiency of a heaving airfoil at different mean angles of attack

    Energy Technology Data Exchange (ETDEWEB)

    Martín-Alcántara, A.; Fernandez-Feria, R. [Universidad de Málaga, Andalucía Tech, E. T. S. Ingeniería Industrial, Dr Ortiz Ramos s/n, 29071 Málaga (Spain); Sanmiguel-Rojas, E. [Área de Mecánica de Fluidos, Universidad de Jaén, Campus de las Lagunillas, 23071 Jaén (Spain)

    2015-07-15

    The thrust efficiency of a two-dimensional heaving airfoil is studied computationally for a low Reynolds number using a vortex force decomposition. The auxiliary potentials that separate the total vortex force into lift and drag (or thrust) are obtained analytically by using an elliptic airfoil. With these auxiliary potentials, the added-mass components of the lift and drag (or thrust) coefficients are also obtained analytically for any heaving motion of the airfoil and for any value of the mean angle of attack α. The contributions of the leading- and trailing-edge vortices to the thrust during their down- and up-stroke evolutions are computed quantitatively with this formulation for different dimensionless frequencies and heave amplitudes (St{sub c} and St{sub a}) and for several values of α. Very different types of flows, periodic, quasi-periodic, and chaotic described as St{sub c}, St{sub a}, and α, are varied. The optimum values of these parameters for maximum thrust efficiency are obtained and explained in terms of the interactions between the vortices and the forces exerted by them on the airfoil. As in previous numerical and experimental studies on flapping flight at low Reynolds numbers, the optimum thrust efficiency is reached for intermediate frequencies (St{sub c} slightly smaller than one) and a heave amplitude corresponding to an advance ratio close to unity. The optimal mean angle of attack found is zero. The corresponding flow is periodic, but it becomes chaotic and with smaller average thrust efficiency as |α| becomes slightly different from zero.

  13. Increase in the maximum lift of an airplane wing due to a sudden increase in its effective angle of attack resulting from a gust

    Science.gov (United States)

    Kramer, Max

    1932-01-01

    Wind-tunnel tests are described, in which the angle of attack of a wing model was suddenly increased (producing the effect of a vertical gust) and the resulting forces were measured. It was found that the maximum lift coefficient increases in proportion to the rate of increase in the angle of attack. This fact is important for the determination of the gust stresses of airplanes with low wing loading. The results of the calculation of the corrective factor are given for a high-performance glider and a light sport plane of conventional type.

  14. 1.5 μm lidar anemometer for true air speed, angle of sideslip, and angle of attack measurements on-board Piaggio P180 aircraft

    International Nuclear Information System (INIS)

    Lidar (light detection and ranging) is a well-established measurement method for the prediction of atmospheric motions through velocity measurements. Recent advances in 1.5 μm Lidars show that the technology is mature, offers great ease of use, and is reliable and compact. A 1.5 μm airborne Lidar appears to be a good candidate for airborne in-flight measurement systems. It allows measurements remotely, outside aircraft aerodynamic disturbance, and absolute air speed (no need for calibration) with great precision in all aircraft flight domains. In the framework of the EU AIM2 project, the ONERA task has consisted of developing and testing a 1.5 μm anemometer sensor for in-flight airspeed measurements. The objective of this work is to demonstrate that the 1.5 μm Lidar sensor can increase the quality of the data acquisition procedure for aircraft flight test certification. This article presents the 1.5 μm anemometer sensor dedicated to in-flight airspeed measurements and describes the flight tests performed successfully on-board the Piaggio P180 aircraft. Lidar air data have been graphically compared to the air data provided by the aircraft flight test instrumentation (FTI) in the reference frame of the Lidar sensor head. Very good agreement of true air speed (TAS) by a fraction of ms−1, angle of sideslip (AOS), and angle of attack (AOA) by a fraction of degree were observed. (special issue article)

  15. Flight Investigation of a Roll-stabilized Missile Configuration at Varying Angles of Attack at Mach Numbers Between 0.8 and 1.79

    Science.gov (United States)

    Zarovsky, Jacob; Gardiner, Robert A

    1957-01-01

    A missile research model was flown at supersonic speed to determine the quality of automatic roll stabilization at varying angles of attack. Aerodynamic rolling and pitching derivatives were determined from the flight record. It was concluded that the combination of the gyro-actuated automatic pilot with wing-tip ailerons provided adequate roll stabilization under conditions encountered in flight.

  16. A physical model of asymmetric vortices flow structure in regular state over slender body at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    邓学蓥; 王刚; 陈学锐; 王延奎; 刘沛清; 郗忠祥

    2003-01-01

    In subcritical Reyolds number flow region, the repeatable and determinate asymmetric vortices flow at regular state can be obtained by manually setting mini-perturbation on the nose of a pointed ogive-cylinder model at high angle of attack and zero side slip. Test results of this study involve surface pressure distributions, sectional-side-force distributions and flow visualizations. The analyses of these results revealed a complicated multi-vortices system at regular state in which asymmetric twin vortices with inception region and fully developed region, asymmetric triple vortices, four vortices region, five vortices region and Karman-vortex-street-like flow region are developed along the slender body. The correlation between multi-vortices system structures and corresponding sectional-side-force distribution is given. The behaviors of multi-vortices flow structure at the peculiar points of sectional-side-force distributions and characteristics of corresponding pressure distribution are analysed. Finally, a physical model of asymmetric multi-vortices flow structure in regular state over slender body is developed.

  17. Validation of aerodynamic parameters at high angles of attack for RAE high incidence research models

    Science.gov (United States)

    Ross, A. Jean; Edwards, Geraldine F.; Klein, Vladislav; Batterson, James G.

    1987-01-01

    Two series of free-flight tests have been conducted for combat aircraft configuration research models in order to investigate flight behavior near departure conditions as well as to obtain response data from which aerodynamic characteristics can be derived. The structure of the mathematical model and values for the mathematical derivatives have been obtained through an analysis of the first series, using stepwise regression. The results thus obtained are the bases of the design of active control laws. Flight test results for a novel configuration are compared with predicted responses.

  18. Aerodynamic coefficients of plain and helically filleted twin circular cylinders for varying wind angles of attack

    DEFF Research Database (Denmark)

    Acampora, Antonio; Georgakis, Christos T.

    2013-01-01

    vary from those estimated through use of aerodynamic coefficients of single circular cylinders, as reported in literature. To address this issue, wind tunnel tests were performed on a 1:2.3 scale section model of the Øresund Bridge cables, with and without the presence of helical fillets. In this paper......Moderate vibrations continue to be recorded on the Øresund Bridge twin-stay cables. System identification techniques have been applied to investigate the aerodynamic characteristics of the cables based on ambient vibration measurements. As might be expected, the measured aerodynamic damping ratios...

  19. A Study of 2D Separated Cascade Flow at Large Angles of Attack Using Euler Equations

    Institute of Scientific and Technical Information of China (English)

    YeDajun; LiuWeidong; 等

    1992-01-01

    This paper presents a numerical simulation method developed for separated flow in cascades using Euler equations and demonstrates the Feasibility of this method MacCOrmack's two-steps explicit finite difference scheme is used to discretize the equations in conservation form,and the artificial viscosity is added to the discretized inviscid equations by means of the self-adapted filter technique.The initial separation boundary is given according to simple experimental results.The numerical simulation results including subsonic and transonic turbine cascades flow with of without separation show that the fundamental idea of this numerical method is reasonable and simple.The present stude indicates that for solving certain engineering problems it is a simple and effective tool for adding some viscosity corrections to inviscld flow model,especially the current when the Navier-Stokes equations have not been solved very effectively for verious complicated flows in turbonachinery.

  20. Drag prediction for blades at high angle of attack using CFD

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Michelsen, J.A.

    2004-01-01

    are known to severely overpredict drag. We then demonstrate that the computed drag distribution along the plate span deviate from the general expectation of 2D behavior at the central part of the plate, an important finding in connection with the theoretical estimation of drag behavior on wind turbine...

  1. Influences of attack angle and mach number on aerodynamic characters of typical sections of extra-long blade in a steam turbine

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On super-sonic or trans-sonic planar cascade wind tunnel of free jet intermittent type, wind blowing experiments were performed on the typical sections of stator and rotor blades in the last stage of ultra-ultra-critical steam turbine with extra-long blade of 1200mm. The influences of attack angle and Mach number on the aerodynamic performances of these sections of the blade profiles were verified, and their operating ranges were also specified.

  2. BiGlobal linear stability analysis on low-Re flow past an airfoil at high angle of attack

    Science.gov (United States)

    Zhang, Wei; Samtaney, Ravi

    2016-04-01

    We perform BiGlobal linear stability analysis on flow past a NACA0012 airfoil at 16° angle of attack and Reynolds number ranging from 400 to 1000. The steady-state two-dimensional base flows are computed using a well-tested finite difference code in combination with the selective frequency damping method. The base flow is characterized by two asymmetric recirculation bubbles downstream of the airfoil whose streamwise extent and the maximum reverse flow velocity increase with the Reynolds number. The stability analysis of the flow past the airfoil is carried out under very small spanwise wavenumber β = 10-4 to approximate the two-dimensional perturbation, and medium and large spanwise wavenumbers (β = 1-8) to account for the three-dimensional perturbation. Numerical results reveal that under small spanwise wavenumber, there are at most two oscillatory unstable modes corresponding to the near wake and far wake instabilities; the growth rate and frequency of the perturbation agree well with the two-dimensional direct numerical simulation results under all Reynolds numbers. For a larger spanwise wavenumber β = 1, there is only one oscillatory unstable mode associated with the wake instability at Re = 400 and 600, while at Re = 800 and 1000 there are two oscillatory unstable modes for the near wake and far wake instabilities, and one stationary unstable mode for the monotonically growing perturbation within the recirculation bubble via the centrifugal instability mechanism. All the unstable modes are weakened or even suppressed as the spanwise wavenumber further increases, among which the stationary mode persists until β = 4.

  3. BiGlobal linear stability analysis on low-Re flow past an airfoil at high angle of attack

    KAUST Repository

    Zhang, Wei

    2016-04-04

    We perform BiGlobal linear stability analysis on flow past a NACA0012 airfoil at 16° angle of attack and Reynolds number ranging from 400 to 1000. The steady-state two-dimensional base flows are computed using a well-tested finite difference code in combination with the selective frequency damping method. The base flow is characterized by two asymmetric recirculation bubbles downstream of the airfoil whose streamwise extent and the maximum reverse flow velocity increase with the Reynolds number. The stability analysis of the flow past the airfoil is carried out under very small spanwise wavenumber β = 10−4 to approximate the two-dimensional perturbation, and medium and large spanwise wavenumbers (β = 1–8) to account for the three-dimensional perturbation. Numerical results reveal that under small spanwise wavenumber, there are at most two oscillatory unstable modes corresponding to the near wake and far wake instabilities; the growth rate and frequency of the perturbation agree well with the two-dimensional direct numerical simulation results under all Reynolds numbers. For a larger spanwise wavenumber β = 1, there is only one oscillatory unstable mode associated with the wake instability at Re = 400 and 600, while at Re = 800 and 1000 there are two oscillatory unstable modes for the near wake and far wake instabilities, and one stationary unstable mode for the monotonically growing perturbation within the recirculation bubble via the centrifugal instability mechanism. All the unstable modes are weakened or even suppressed as the spanwise wavenumber further increases, among which the stationary mode persists until β = 4.

  4. Methods for root effects, tip effects and extending the angle of attack range to {+-} 180 deg., with application to aerodynamics for blades on wind turbines and propellers

    Energy Technology Data Exchange (ETDEWEB)

    Montgomerie, Bjoern

    2004-06-01

    For wind turbine and propeller performance calculations aerodynamic data, valid for several radial stations along the blade, are used. For wind turbines the data must be valid for the 360 degree angle of attack range. The reason is that all kinds of abnormal conditions must be analysed especially during the design of the turbine. Frequently aerodynamic data are available from wind tunnel tests where the angle of attack range is from say -5 to +20 degrees. This report describes a method to extend such data to be valid for {+-} 180 degrees. Previously the extension of data has been very approximate following the whim of the moment with the analyst. Furthermore, the Himmelskamp effect at the root and tip effects are treated in the complete method.

  5. 鱼雷纯方位攻击提前角优化分析%Optimization of Torpedo Bearing-only Attack Angle in Advance

    Institute of Scientific and Technical Information of China (English)

    董严红; 卫翔; 孙春生

    2014-01-01

    The bearing-only torpedo attack is a method that submarine attack only based on the change of target bearing. The hitting probability of torpedo is an important content of weapon research and operational use,and it is also a necessary basis of the torpedo operational effectiveness. Through the analysis of process of bearing-only torpedo attack,the mathematical simulation model is built up, performing the large sample simulation,the optimal solutions of torpedo attack angle in advance in different conditions could be taken out.%鱼雷纯方位攻击是潜艇因无法解算目标运动要素时,依靠方位变化对目标实施快速鱼雷攻击的一种方法。鱼雷命中概率是武器装备研究和作战使用研究的重要内容,也是鱼雷武器作战效能评估的主要依据。通过分析自导鱼雷纯方位攻击的使用过程,建立了相应的数学和仿真模型,并采用大样本仿真的方法,得出不同情况下鱼雷攻击提前角的最优解。

  6. A PIV study of separated flow around a 2-D airfoil at high angles of attack in a low speed wind tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Holm, R.; Gustavsson, Jonas

    1999-08-01

    Wind tunnel tests were carried out in order to acquire experimental data for validation of numerical results from Navier-Stokes calculations (CFD-simulations) on airfoils at high angles of attack. The tests were performed on the 21% thick FFA-W3-211 airfoil geometry, 2-dimensional wind tunnel model with 0.45 m chord and 2 m span. The purpose of the study was to examine the flow field around the airfoil at 8 deg and 15 deg angle of attack, in particular to determine the position of the separation and the recirculating region. The wind tunnel tests were carried out at Re=1.25 million. The used measurement techniques were pressure measurement, oil flow visualisation and PIV (Particle Image Velocimetry). The boundary layer transition was trigged at a fixed position (x/c=0.026 on the suction side and x/c=0.312 on the pressure side) by means of an adhesive zigzag tape. The uncertainties regarding the position of transition was thereby reduced. Based on the velocity vector field obtained by the PIV data the velocity profile, boundary layer quantities and the back-flow coefficient were derived. The back-flow coefficient was then used as a criterion for separation. The conclusions of the study were: The flow field was determined by PIV and available for comparison with CFD-results. Based on the velocity field the separation position, the velocity profile at different chordwise positions and boundary layer quantities were derived. The separation position, for 15 deg angle of attack, was determined in the PIV measurements to x/c 0.39{+-}0.03 and in the pressure measurements to x/c = 0.40{+-}0.05 and somewhat subjectively in the oil flow to x/c >> 0.42. The data are available on file format for comparison with CFD results.

  7. A modification to linearized theory for prediction of pressure loadings on lifting surfaces at high supersonic Mach numbers and large angles of attack

    Science.gov (United States)

    Carlson, H. W.

    1979-01-01

    A new linearized-theory pressure-coefficient formulation was studied. The new formulation is intended to provide more accurate estimates of detailed pressure loadings for improved stability analysis and for analysis of critical structural design conditions. The approach is based on the use of oblique-shock and Prandtl-Meyer expansion relationships for accurate representation of the variation of pressures with surface slopes in two-dimensional flow and linearized-theory perturbation velocities for evaluation of local three-dimensional aerodynamic interference effects. The applicability and limitations of the modification to linearized theory are illustrated through comparisons with experimental pressure distributions for delta wings covering a Mach number range from 1.45 to 4.60 and angles of attack from 0 to 25 degrees.

  8. Verification of the Shear-Stress Transfer Model and its Modifications in the Calculation of a Turbulent Flow Around a Semicircular Airfoil with a Zero Angle of Attack

    Science.gov (United States)

    Isaev, S. A.; Baranov, P. A.; Zhukova, Yu. V.; Kalinin, E. I.; Miau, J. J.

    2016-01-01

    A comparative analysis of different versions of the Menter shear-stress transfer model, including with correction for the curvature of streamlines, has been performed as applied to a periodic flow around a semicircular airfoil with a zero angle of attack at Re = 45,000. A comparison of the calculated aerodynamic coefficients Cx and Cy and the surface distribution of the pressure coefficient, averaged over the period of oscillations of the lift coefficient Cy, with the corresponding experimental data has shown that the Menter shear-stress transfer model modified within the framework of the Rody-Leshtsiner-Isaev approach with the use of the inverse function of the Richardson number correcting the eddy viscosity of a flow with a semiempirical Isaev-Kharchenko-Usachov constant equal to 0.02 is preferred compared to the other versions of this model. The errors of the calculations performed with the use of the multiblock computational technologies based on intersecting structured meshes of different scales were analyzed. The interrelation between the evolution of the structure of the periodic flow around the semicircular airfoil and the distribution of its integral force characteristics in the period of Cy oscillations is discussed.

  9. Aerodynamic Characteristics of a Circular Cylinder at Mach Number of 6.86 and Angles of Attack up to 90 Degrees

    Science.gov (United States)

    Penland, Jim A

    1954-01-01

    Pressure-distribution and force tests of a circular cylinder have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.86, a Reynolds number of 129,000 based on diameter, and angles of attack up to 90 degrees. The results are compared with the hypersonic approximation of Grimminger, Williams, and Young and with a simple modification of the Newtonian flow theory. The comparison of experimental results shows that either theory gives adequate general aerodynamic characteristics but that the modified Newtonian theory gives a more accurate prediction of the pressure distribution. The calculated crossflow drag coefficients plotted as a function of crossflow Mach number were found to be in reasonable agreement with similar results obtained from other investigations at lower supersonic Mach numbers. Comparison of the results of this investigation with data obtained at a lower Mach number indicates that the drag coefficient of a cylinder normal to the flow is relatively constant for Mach numbers above about 4.

  10. Nomogram for correcting drag and angle of attack of an airfoil model in an air stream of finite diameter

    Science.gov (United States)

    1924-01-01

    In experimenting with airfoil models in a wind tunnel, the magnitude of the forces acting on the model is affected by the fact that the air stream in which the model is suspended, has a restricted cross-section. In order to utilize the results for an airplane in an unlimited quantity of air, a correction must be made. The magnitude of this correction was determined by Prandtl by the application of his wing theory.

  11. Influence of wind angle of attack and isotropic turbulence on wind-induced vibrations of ice-accreted bridge cables

    OpenAIRE

    Pospíšil, S.; Trush, A. (Arsenii); Kuznetsov, S. (Sergeii); Kozmar, H.; Náprstek, J. (Jiří)

    2016-01-01

    Bridge-supporting cables and mast guys with high flexibility and low damping often experience vibrations with large amplitudes that may have consequently destructive effects on supported structures. Surface roughness and ice accretion are important issues, as they can considerably alter aerodynamic characteristics of bridge cables. This study describes wind-tunnel experiments on vortex-induced vibration of cylindrical section models with the deliberately adjusted natural frequency f = 5 Hz. T...

  12. Aerodynamic Force Characteristics of a Series of Lifting Cone and Cone-Cylinder Configurations at a Mach Number of 6.83 and Angles of Attack up to 130 Deg

    Science.gov (United States)

    Penland, Jim A.

    1961-01-01

    Force tests of a series of right circular cones having semivertex angles ranging from 5 deg to 45 deg and a series of right circular cone-cylinder configurations having semivertex angles ranging from 5 deg to 20 deg and an afterbody fineness ratio of 6 have been made in the Langley 11-inch hypersonic tunnel at a Mach number of 6.83, a Reynolds number of 0.24 x 10.6 per inch, and angles of attack up to 130 deg. An analysis of the results made use of the Newtonian and modified Newtonian theories and the exact theory. A comparison of the experimental data of both cone and cone-cylinder configurations with theoretical calculations shows that the Newtonian concept gives excellent predictions of trends of the force characteristics and the locations with respect to angle of attack of the points of maximum lift, maximum drag, and maximum lift-drag ratio. Both the Newtonian a.nd exact theories give excellent predictions of the sign and value of the initial lift-curve slope. The maximum lift coefficient for conical bodies is nearly constant at a value of 0.5 based on planform area for semivertex angles up to 30 deg. The maximum lift-drag ratio for conical bodies can be expected to be not greater than about 3.5, and this value might be expected only for slender cones having semivertex angles of less than 5 deg. The increments of angle of attack and lift coefficient between the maximum lift-drag ratio and the maximum lift coefficient for conical bodies decrease rapidly with increasing semivertex angles as predicted by the modified Newtonian theory.

  13. Investigation of normal force and moment coefficients for an AUV at nonlinear angle of attack and sideslip range

    Digital Repository Service at National Institute of Oceanography (India)

    Barros, E.A. de; Dantas, J.L.D.; Pascoal, A.M.; Desa, E.S.

    and may improve the es- timation of stability derivatives for maneuverability prediction and design of linear control strategies. The axi-symetric bare-hull geometry has been thoroughly studied, and in particular, the shape proposed by Myring [24] has been... for the research. II. CFD SIMULATION This section describes the results of CFD analysis of the MAYA AUV (see Fig. 1), the particulars of which are con- densed in Table I. Fig. 1. MAYA AUV. TABLE I MAIN PARAMETERS OF THE HULL The vehicle has a Myring-type body...

  14. Signs of a Heart Attack

    Science.gov (United States)

    ... attack Heart Health and Stroke Signs of a heart attack Related information Make the Call. Don't Miss ... to top More information on Signs of a heart attack Read more from womenshealth.gov Make the Call, ...

  15. Wind-Tunnel Investigation at a Mach Number of 2.01 of the Aerodynamic Characteristics in Combined Angles of Attack and Sideslip of Several Hypersonic Missile Configurations with Various Canard Controls

    Science.gov (United States)

    Robinson, R. B.

    1958-01-01

    An investigation of the aerodynamic characteristics of several hypersonic missile configurations with various canard controls for an angle-of-attack range from 0 deg to about 28 deg at sideslip angles of about 0 deg and 4 deg at a Mach number of 2.01 has been made in the Langley 4- by 4-foot supersonic pressure tunnel. The configurations tested we re a body alone which had a ratio of length to diameter of 10, the b ody with a 10 deg flare, the body with cruciform fins of 5 deg or 15 deg apex angle, and a flare-stabilized rocket model with a modified Von Karman nose. Various canard surfaces for pitch control only were te sted on the body with the 10 deg flare and on the body with both sets of fins. The results indicated that the addition of a flared afterbody or cruciform fins produced configurations which were longitudinally and directionally stable. The body with 5 deg fins should be capable of producing higher normal accelerations than the flared body. A l l of the canard surfaces were effective longitudinal controls which produced net positive increments of normal force and pitching moments which progressively decreased with increasing angle of attack.

  16. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    OpenAIRE

    Yi-Hsun Wang; Ching-Hao Mao; Hahn-Ming Lee

    2010-01-01

    Web applications suffer from cross-site scripting (XSS) attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of...

  17. 攻角对一种深水炸弹入水散布特性的影响%Analysis on Attack Angle Impacted Dispersion Characteristic of Depth Charge Water Entry

    Institute of Scientific and Technical Information of China (English)

    张世林; 阮晓亮

    2014-01-01

    研究攻角对深水炸弹入水后的散布特性影响,针对一种新型深水炸弹总体外形,通过试验分析了不同攻角下入水时的弹着点散布状态,试验结果表明:随着攻角的增加,落点散布有增大的趋势,随着水深的增加,落点散布增加,而增加的趋势逐渐减小;深水炸弹的质量偏心对落点的分布有着很大影响。%To research how attack angle impacted dispersion characteristic of depth charge after water en-try,the depth charge with a new general shape has been taken into experiment to research and record its points of impact when water entry with different attack angle. Research results show that:impact disper-sion increases as the increasing of attack angle;when water depth increases impact dispersion also increa-ses,but the trend is decreasing gradually;mass eccentricity of depth charge has great influence on impact dispersion.

  18. Blocking of Brute Force Attack

    Directory of Open Access Journals (Sweden)

    M.Venkata Krishna Reddy

    2012-08-01

    Full Text Available A common threat Web developers face is a password-guessing attack known as a brute-force attack. A brute-force attack is an attempt to discover a password by systematically trying every possible combination of letters, numbers, and symbols until you discover the one correct combination that works. If your Web site requires user authentication, you are a good target for a brute-force attack. An attacker can always discover a password through a brute-force attack, but the downside is that it could take years to find it. Depending on the password's length and complexity, there could be trillions of possible combinations. To speed things up a bit, a brute-force attack could start with dictionary words or slightly modified dictionary words because most people will use those rather than a completely random password. These attacks are called dictionary attacks or hybrid brute-force attacks. Brute-force attacks put user accounts at risk and flood your site with unnecessary traffic. Hackers launch brute-force attacks using widely available tools that utilize wordlists and smart rule set to intelligently and automatically guess user passwords. Although such attacks are easy to detect, they are not so easy to prevent

  19. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    Directory of Open Access Journals (Sweden)

    Yi-Hsun Wang

    2010-09-01

    Full Text Available Web applications suffer from cross-site scripting (XSS attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of generating mutated XSS attacks in a fully automatic way. Mutated XSS attack generation depends on the analysis of attack vectors and the structural learning mechanism. For the kernel of the learning mechanism, we use a Hidden Markov model (HMM as the structure of the attack vector model to capture the implicit manner of the attack vector, and this manner is benefited from the syntax meanings that are labeled by the proposed tokenizing mechanism. Bayes theorem is used to determine the number of hidden states in the model for generalizing the structure model. The paper has the contributions as following: (1 automatically learn the structure of attack vectors from practical data analysis to modeling a structure model of attack vectors, (2 mimic the manners and the elements of attack vectors to extend the ability of testing tool for identifying XSS vulnerabilities, (3 be helpful to verify the flaws of blacklist sanitization procedures of Web applications. We evaluated the proposed mechanism by Burp Intruder with a dataset collected from public XSS archives. The results show that mutated XSS attack generation can identify potential vulnerabilities.

  20. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    CERN Document Server

    Wang, Yi-Hsun; Lee, Hahn-Ming; 10.4204/EPTCS.35.2

    2010-01-01

    Web applications suffer from cross-site scripting (XSS) attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of generating mutated XSS attacks in a fully automatic way. Mutated XSS attack generation depends on the analysis of attack vectors and the structural learning mechanism. For the kernel of the learning mechanism, we use a Hidden Markov model (HMM) as the structure of the attack vector model to capture the implicit manner of the attack vector, and this manner is benefited from the syntax meanings that are labeled by the proposed tokenizing mechanism. Bayes theorem is used to determine the number of hidden states in the model...

  1. Energy harvesting performance of an oscillatory foil with elliptic sine attack angle%基于椭圆正弦攻角运动振动翼的能量采集性能分析

    Institute of Scientific and Technical Information of China (English)

    徐文华; 许国冬; 张庆力

    2015-01-01

    振动翼作为一种有效的潮流能、风能换能装置,可将潮流或风的动能转化为机械动能推动电机发电。该文通过调整机翼的周期性垂向运动与旋转运动实现机翼与来流的有效攻角控制,来流对机翼的流体动升力可推动机械装置往复运动并转换为电机的转动。假定机翼表面的边界层极薄,黏性仅在边界层内部作用,泻出涡仅从机翼的尾缘处泻出,引入势流理论,采用边界元法与泻出涡模型模拟机翼边界层的外部流场。主要分析了机翼以椭圆正弦为有效攻角运动的振动运动的能量采集性能,计算NACA0012机翼在不同运动频率、振动幅值与有效攻角时的能量采集效率,并分析了椭圆正弦K 参数对能量采集的影响,研究实现高效率能量采集的机理。%Oscillatory foil is an effective energy harvesting device to extract energy from incoming flow, including current and wind. By adjusting the periodical vertical and rotational motion, the effective attack angle can be controlled;and the fluid loads can be utilized to drive the reciprocating motion of mechanical device. Assuming that the boundary layer is thin and the viscosity only has effects within the layer, the velocity potential is introduced to simulate the outer fluid flow through boundary element method and vortex shedding scheme. The energy harvesting performance of NACA0012 foil in oscillatory motion, where the effective attack angle is elliptic sine function, is analyzed. The energy extraction efficiency at various heave amplitude, the effective attack angle and Strouhal number is calculated, the effects of K parameter on the energy efficiency have been analyzed;the mechanics to achieve high efficiency is investigated.

  2. Local heat transfer around a wall-mounted cube. Case of the attack angle of 45 deg.; Rippotai tokki mawari no kyokusho netsu dentatsu. Katamukikaku 45 degrees no baai

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H.; Igarashi, T.; Tsutsui, T. [National Defense Academy, Kanagawa (Japan)

    1999-11-25

    An experimental study was performed to investigate the local heat transfer around a cube mounted on the wall. The cube lied in the turbulent boundary layer. The flow angle of attack to the cube was 15 degree. The Reynolds number ranged from 4.2 x 10{sup 3} to 3.3 x 10{sup 4}. The surface temperature distributions around time cube were measured with thermocouples tinder the condition of a constant heat flux. The local h eat transfer is very high near the front corner on the top face of the cube. This high heat transfer region extends from the front corner to downstream along both edges. This is caused by the formation of lamb horn vortex. The local heat transfer is also high in time region of horseshoe vortex formed a round the cube. On the wall behind the cube, there is a pair of minimum heat transfer region. The average Nusselt number on each face of the cube is given as a function of Reynolds number. The overall Nusselt number of time cube is expressed by Nu{sub m}=0.43Re{sup 0.58}. (author)

  3. The numerical simulation of separated flow at large attack angles for a wind turbine airfoil%风力机翼型大攻角分离流的数值模拟

    Institute of Scientific and Technical Information of China (English)

    王文龙; 何斌; 傅洁; 范钦珊

    2012-01-01

    为了准确预测风力机翼型在大攻角下分离流动的气动性能,并且为风力机的设计与安全运行提供一种可靠的数值模拟手段,针对某风力机专用翼型,分别采用基于非定常不可压缩Navier-Stokes方程的大涡模拟(LES)模型、RNG κ-ε模型和Standard κ-ε模型对其气动性能进行数值模拟,并计算出翼型攻角为35 ~90°,雷诺数为2×106时的气动力参数.将不同湍流模型的计算结果与风洞试验数据进行比较,并分析流场结构.分析结果表明,LES模型能够准确地模拟出翼型表面的分离流动,计算结果与试验数据取得了很好的一致性,并且优于RNG κ-ε模型和Standard κ-ε模型的模拟结果.%In order to accurately predict the aerodynamic performance of the separated flows of a wind turbine airfoil at large attack angles and provide a reliable numerical simulation method for the design and safe operation of the wind turbine, aiming at a certain type of wind turbine airfoil, an aerodynamic performance was numerically simulated by using LES model, RNG k-e model and Standard k-e model based on unsteady incompressible Navier-Stokes equations respectively, and the aerodynamic parameters at various attack angles ranging from 35 ° to 90 ° was calculated when the Reynolds number is 2×l06. By comparing the calculation results of the different turbulence models with wind tunnel test data and analyzing the flow field, it is shown that LES model can accurately simulate the separation of the airfoil surface flows, and its calculated results, which are better than RNG k -s model's and Standard k -e model's, agree well with the experimental data.

  4. Some Aspects of the Modified Newtonian and Prandtl-Meyer-Expansion Method for Axisymmetric Blunt Bodies at Zero Angle of Attack

    Science.gov (United States)

    Wagner, Richard D., Jr.

    1959-01-01

    In a recent article on hypersonic flow, Lees and Kubota suggested a modification of the local-expansion method to predict the surface pressures in the region of a nose-cylinder junction where Newtonian theory fails. The modification consists of matching the Newtonian pressure distribution and the Prandtl-Meyer relation at the point on the nose surface where both the pressure and the pressure gradient, predicted by these two solution, are equal. With this approximation, the pressure distribution can be predicted quite accurately up to the nose-cylinder junction for blunt-nosed bodies of continuous curvature, provided centrifugal-force effects are negligible. The purpose of this note is to facilitate the application of Lees' suggestion and to draw attention to some of its consequences.

  5. Perception of perspective angles

    NARCIS (Netherlands)

    Erkelens, C.J.

    2015-01-01

    We perceive perspective angles, that is, angles that have an orientation in depth, differently from what they are in physical space. Extreme examples are angles between rails of a railway line or between lane dividers of a long and straight road. In this study, subjects judged perspective angles bet

  6. Automated Generation of Attack Trees

    DEFF Research Database (Denmark)

    Vigo, Roberto; Nielson, Flemming; Nielson, Hanne Riis

    2014-01-01

    Attack trees are widely used to represent threat scenarios in a succinct and intuitive manner, suitable for conveying security information to non-experts. The manual construction of such objects relies on the creativity and experience of specialists, and therefore it is error-prone and impractica...

  7. The Timing of Terrorist Attacks

    DEFF Research Database (Denmark)

    Jensen, Thomas

    2016-01-01

    I use a simple optimal stopping model to derive policy relevant insights on the timing of one-shot attacks by small autonomous terrorist units or “lone wolf” individuals. A main insight is that an increase in proactive counterterrorism measures can lead to a short term increase in the number of a...

  8. Wind tunnel research concerning lateral control devices, particularly at high angles of attack VII : Handley Page tip and full-span slots with ailerons and spoilers

    Science.gov (United States)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    Tests were made with ordinary ailerons and different sizes of spoilers on rectangular Clark Y wing models with Handley Page tip and full span slots. The tests showed the effect of the control devices on the general performance of the wings as well as on the lateral control and lateral stability characteristics.

  9. Performance of attack strategies on modular networks

    CERN Document Server

    da Cunha, Bruno Requião

    2016-01-01

    Vulnerabilities of complex networks have became a trend topic in complex systems recently due to its real world applications. Most real networks tend to be very fragile to high betweenness adaptive attacks. However, recent contributions have shown the importance of interconnected nodes in the integrity of networks and module-based attacks have appeared promising when compared to traditional malicious non-adaptive attacks. In the present work we deeply explore the trade-off associated with attack procedures, introducing a generalized robustness measure and presenting an attack performance index that takes into account both robustness of the network against the attack and the run-time needed to obtained the list of targeted nodes for the attack. Besides, we introduce the concept of deactivation point aimed to mark the point at which the network stops to function properly. We then show empirically that non-adaptive module-based attacks perform better than high degree and betweenness adaptive attacks in networks ...

  10. Perfection of Recent Attacks using IP

    Directory of Open Access Journals (Sweden)

    A. RENGARAJAN

    2012-02-01

    Full Text Available The Internet threat monitoring (ITM systems have been deployed to detect widespread attacks on the Internet in recent years. However, the effectiveness of ITM systems critically depends on the confidentiality of the location of their monitors. If adversaries learn the monitor locations of an ITM system, they can bypass the monitors and focus on the uncovered IP address space without being detected. In this paper, we study a new class of attacks, the invisible LOCalization (iLOC attack. The iLOC attack can accurately and invisibly localize monitors of ITM systems. In the iLOC attack, the attacker launches low-rate port-scan traffic, encoded with a selected pseudo noise code (PN-code, to targeted networks. While the secret PN-code is invisible to others, the attacker can accurately determine the existence of monitors in the targeted networks based on whether the PN-code is embedded in the report data queried from the data center of the ITM system. We formally analyze the impact of various parameters on attack effectiveness. We implement the iLOC attack and conduct the performance evaluation on a real-world ITM system to demonstrate the possibility of such attacks. We also conduct extensive simulations on the iLOC attack using real-world traces. Our data show that the iLOC attack can accurately identify monitors while being invisible to ITM systems. Finally, we present a set of guidelines to counteract the iLOC attack.

  11. Diabetes Ups Risk of Heart Attack Death

    Science.gov (United States)

    ... 159557.html Diabetes Ups Risk of Heart Attack Death Study points to need for better coordinated care, ... people with diabetes have a higher risk of death after a heart attack. "We knew that following ...

  12. Panic attacks simulate presence of somatic illnesses

    OpenAIRE

    Latas Milan; Soldatović Ivan; Stamenović Marko; Starčević Vladan

    2009-01-01

    Introduction. Panic attacks are characterized with sudden attacks of anxiety with numerous somatic symptoms, such as palpitations, tachycardia, tachypnea, nausea, vertigo. The objective of this study was to analyze symptoms of panic attacks in patients with panic disorder, especially, to determine the specific relationship of somatic and neurological symptoms of panic attacks in boundaries of somatic systems. Material and methods. The study sample consisted of 97 patients with primary diagnos...

  13. What Are the Symptoms of a Heart Attack?

    Science.gov (United States)

    ... on Twitter. What Are the Symptoms of a Heart Attack? Not all heart attacks begin with the sudden, ... This Content: NEXT >> Featured Video What is a heart attack? 05/22/2014 Describes how a heart attack ...

  14. Classification of Attacks in Wireless Sensor Networks

    OpenAIRE

    Messai, Mohamed-Lamine

    2014-01-01

    In wireless sensor networks (WSNs), security has a vital importance. Recently, there was a huge interest to propose security solutions in WSNs because of their applications in both civilian and military domains. Adversaries can launch different types of attacks, and cryptography is used to countering these attacks. This paper presents challenges of security and a classification of the different possible attacks in WSNs. The problems of security in each layer of the network's OSI model are dis...

  15. Percolation of localized attack on complex networks

    CERN Document Server

    Shao, Shuai; Stanley, H Eugene; Havlin, Shlomo

    2014-01-01

    The robustness of complex networks against node failure and malicious attack has been of interest for decades, while most of the research has focused on random attack or hub-targeted attack. In many real-world scenarios, however, attacks are neither random nor hub-targeted, but localized, where a group of neighboring nodes in a network are attacked and fail. In this paper we develop a percolation framework to analytically and numerically study the robustness of complex networks against such localized attack. In particular, we investigate this robustness in Erd\\H{o}s-R\\'{e}nyi networks, random-regular networks, and scale-free networks. Our results provide insight into how to better protect networks, enhance cybersecurity, and facilitate the design of more robust infrastructures.

  16. Detecting Denial of Service Attacks in Tor

    Science.gov (United States)

    Danner, Norman; Krizanc, Danny; Liberatore, Marc

    Tor is currently one of the more popular systems for anonymizing near real-time communications on the Internet. Recently, Borisov et al. proposed a denial of service based attack on Tor (and related systems) that significantly increases the probability of compromising the anonymity provided. In this paper, we propose an algorithm for detecting such attacks and examine the effectiveness of the obvious approach to evading such detection. We implement a simplified version of the detection algorithm and study whether the attack may be in progress on the current Tor network. Our preliminary measurements indicate that the attack was probably not implemented during the period we observed the network.

  17. Panic attacks simulate presence of somatic illnesses

    Directory of Open Access Journals (Sweden)

    Latas Milan

    2009-01-01

    Full Text Available Introduction. Panic attacks are characterized with sudden attacks of anxiety with numerous somatic symptoms, such as palpitations, tachycardia, tachypnea, nausea, vertigo. The objective of this study was to analyze symptoms of panic attacks in patients with panic disorder, especially, to determine the specific relationship of somatic and neurological symptoms of panic attacks in boundaries of somatic systems. Material and methods. The study sample consisted of 97 patients with primary diagnosis of panic disorder, without any acute, severe and unstable somatic illness. The presence and frequency of symptoms of panic attacks were estimated by the Panic Disorder Questionnaire. Results. The study results indicate that the most frequent symptoms of panic attacks were cardiological signs (heart pounding or racing and trembling, followed by unsteady and fainting feeling symptoms, sweating, respiratory symptoms and gastroenterological symptoms. The results of correlation analyses indicate that symptoms of panic attacks classified into cardio-vascular, gastro-enterological, respiratory and neuro-otological systems show statistically significant correlations. Conclusion. The results of analyses of symptoms of panic attacks point to their intercorrelation. This specific association of the symptoms, if they are examined on their own in the patients, could lead to false clinical manifestation of some somatic illness. Therefore, it is necessary to analyze adequately and make the proper differential diagnosis of patients with panic disorder.

  18. The cost of attack in competing networks.

    Science.gov (United States)

    Podobnik, B; Horvatic, D; Lipic, T; Perc, M; Buldú, J M; Stanley, H E

    2015-11-01

    Real-world attacks can be interpreted as the result of competitive interactions between networks, ranging from predator-prey networks to networks of countries under economic sanctions. Although the purpose of an attack is to damage a target network, it also curtails the ability of the attacker, which must choose the duration and magnitude of an attack to avoid negative impacts on its own functioning. Nevertheless, despite the large number of studies on interconnected networks, the consequences of initiating an attack have never been studied. Here, we address this issue by introducing a model of network competition where a resilient network is willing to partially weaken its own resilience in order to more severely damage a less resilient competitor. The attacking network can take over the competitor's nodes after their long inactivity. However, owing to a feedback mechanism the takeovers weaken the resilience of the attacking network. We define a conservation law that relates the feedback mechanism to the resilience dynamics for two competing networks. Within this formalism, we determine the cost and optimal duration of an attack, allowing a network to evaluate the risk of initiating hostilities. PMID:26490628

  19. Evaluating Deterioration of Concrete by Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Effects of factors such as water to cement ratio, fly ash and silica fume on the resistance of concrete to sulfate attack were investigated by dry-wet cycles and immersion method. The index of the resistance to sulfate attack was used to evaluate the deterioration degree of concrete damaged by sulfate. The relationship between the resistance of concrete to sulfate attack and its permeability/porosity were analyzed as well as its responding mechanism. Results show that the depth of sulfate crystal attack from surface to inner of concrete can be reduced by decreasing w/c and addition of combining fly ash with silica fume. The variation of relative elastic modulus ratio and relative flexural strength ratio of various specimens before and after being subjected to sulfate attack was compared.

  20. Use of Attack Graphs in Security Systems

    Directory of Open Access Journals (Sweden)

    Vivek Shandilya

    2014-01-01

    Full Text Available Attack graphs have been used to model the vulnerabilities of the systems and their potential exploits. The successful exploits leading to the partial/total failure of the systems are subject of keen security interest. Considerable effort has been expended in exhaustive modeling, analyses, detection, and mitigation of attacks. One prominent methodology involves constructing attack graphs of the pertinent system for analysis and response strategies. This not only gives the simplified representation of the system, but also allows prioritizing the security properties whose violations are of greater concern, for both detection and repair. We present a survey and critical study of state-of-the-art technologies in attack graph generation and use in security system. Based on our research, we identify the potential, challenges, and direction of the current research in using attack graphs.

  1. Spatially localized attacks on interdependent networks: the existence of a finite critical attack size

    CERN Document Server

    Berezin, Yehiel; Danziger, Michael M; Li, Daqing; Havlin, Shlomo

    2013-01-01

    Many real world complex systems such as infrastructure, communication and transportation networks are embedded in space, where entities of one system may depend on entities of other systems. These systems are subject to geographically localized failures due to malicious attacks or natural disasters. Here we study the resilience of a system composed of two interdependent spatially embedded networks to localized geographical attacks. We find that if an attack is larger than a finite (zero fraction of the system) critical size, it will spread through the entire system and lead to its complete collapse. If the attack is below the critical size, it will remain localized. In contrast, under random attack a finite fraction of the system needs to be removed to initiate system collapse. We present both numerical simulations and a theoretical approach to analyze and predict the effect of local attacks and the critical attack size. Our results demonstrate the high risk of local attacks on interdependent spatially embedd...

  2. Automatic Classification of Attacks on IP Telephony

    Directory of Open Access Journals (Sweden)

    Jakub Safarik

    2013-01-01

    Full Text Available This article proposes an algorithm for automatic analysis of attack data in IP telephony network with a neural network. Data for the analysis is gathered from variable monitoring application running in the network. These monitoring systems are a typical part of nowadays network. Information from them is usually used after attack. It is possible to use an automatic classification of IP telephony attacks for nearly real-time classification and counter attack or mitigation of potential attacks. The classification use proposed neural network, and the article covers design of a neural network and its practical implementation. It contains also methods for neural network learning and data gathering functions from honeypot application.

  3. SURVEY OF PACKET DROPPING ATTACK IN MANET

    Directory of Open Access Journals (Sweden)

    A.Janani

    2014-03-01

    Full Text Available Mobile Ad-hoc NETwork (MANET is an application of wireless network with self-configuring mobile nodes. MANET does not require any fixed infrastructure. Its development never has any threshold range. Nodes in MANET can communicate with each other if and only if all the nodes are in the same range. This wide distribution of nodes makes MANET vulnerable to various attacks, packet dropping attack or black hole attack is one of the possible attack. It is very hard to detect and prevent. To prevent from packet dropping attack, detection of misbehavior links and selfish nodes plays a vital role in MANETs. In this paper, a omprehensive investigation on detection of misbehavior links and malicious nodes is carried out.

  4. Situational awareness of a coordinated cyber attack

    Science.gov (United States)

    Sudit, Moises; Stotz, Adam; Holender, Michael

    2005-03-01

    As technology continues to advance, services and capabilities become computerized, and an ever increasing amount of business is conducted electronically the threat of cyber attacks gets compounded by the complexity of such attacks and the criticality of the information which must be secured. A new age of virtual warfare has dawned in which seconds can differentiate between the protection of vital information and/or services and a malicious attacker attaining their goal. In this paper we present a novel approach in the real-time detection of multistage coordinated cyber attacks and the promising initial testing results we have obtained. We introduce INFERD (INformation Fusion Engine for Real-time Decision-making), an adaptable information fusion engine which performs fusion at levels zero, one, and two to provide real-time situational assessment and its application to the cyber domain in the ECCARS (Event Correlation for Cyber Attack Recognition System) system. The advantages to our approach are fourfold: (1) The complexity of the attacks which we consider, (2) the level of abstraction in which the analyst interacts with the attack scenarios, (3) the speed at which the information fusion is presented and performed, and (4) our disregard for ad-hoc rules or a priori parameters.

  5. Forensics Investigation of Web Application Security Attacks

    Directory of Open Access Journals (Sweden)

    Amor Lazzez

    2015-02-01

    Full Text Available Nowadays, web applications are popular targets for security attackers. Using specific security mechanisms, we can prevent or detect a security attack on a web application, but we cannot find out the criminal who has carried out the security attack. Being unable to trace back an attack, encourages hackers to launch new attacks on the same system. Web application forensics aims to trace back and attribute a web application security attack to its originator. This may significantly reduce the security attacks targeting a web application every day, and hence improve its security. The aim of this paper is to carry out a detailed overview about the web application forensics. First, we define the web applications forensics, and we present a taxonomic structure of the digital forensics. Then, we present the methodology of a web application forensics investigation. After that, we illustrate the forensics supportive tools for a web application forensics investigation. After that, we present a detailed presentation of a set of the main considered web application forensics tools. Finally, we provide a comparison of the main considered web application forensics tools.

  6. Research on First Attack Probability Model of an Attacker Level Bombing Anti-air Radars

    Institute of Scientific and Technical Information of China (English)

    LUO Peng-cheng; MU Fu-ling; ZHOU Jing-lun

    2007-01-01

    The paper mainly studies the first attack probability (FAP) of an attacker level bombing anti-air radars through analyzing the radiant point orientation and attack (RPOA) process of attackers. Firstly, the searching target process is analyzed, and a corresponding target finding model is brought forward. Secondly, the target approaching process is concretely analyzed when the attacker levelly bombs the anti-air radar, and a corresponding target approaching model is presented. Finally, a demonstration is given to analyze the major factors in the model and prove its validity.

  7. Logical Modes of Attack in Argumentation Networks

    OpenAIRE

    Gabbay, Dov M.; Garcez, A. S. D. Avila

    2009-01-01

    This paper studies methodologically robust options for giving logical contents to nodes in abstract argumentation networks. It defines a variety of notions of attack in terms of the logical contents of the nodes in a network. General properties of logics are refined both in the object level and in the meta level to suit the needs of the application. The network-based system improves upon some of the attempts in the literature to define attacks in terms of defeasible proofs, the...

  8. The role of sleep in migraine attacks

    Directory of Open Access Journals (Sweden)

    Elaine Inamorato

    1993-11-01

    Full Text Available Migraine attacks may be precipitated by sleep deprivation or excessive sleep and sleep is also associated with relief of migraine attacks. In view of this variable relationship we studied the records of 159 consecutive outpatients of our Headache Unit. In 121 records there was reference to sleep involvement, in 55% by a single form and in 45% by more than one form. When only one form was related, relief was most common (70%. 30% of that group of patients had the migraine attack precipitated by sleep, 24% by deprivation and 6% by sleep excess. When the effects of sleep were multiple, these effects were as expected logically in 65%: «in accordance» group (e.g attack precipitated by sleep deprivation and relieved by sleep onset. In a second group, («conflicting» where the involvement was not logical, there were three different combinations of sleep involvement, possibly due to more than one pathophysiological mechanism.

  9. AN APPROACH OF DEFENDING AGAINST DDOS ATTACK

    Institute of Scientific and Technical Information of China (English)

    Wu Zhijun; Duan Haixin; Li Xing

    2006-01-01

    An approach of defending against Distributed Denial of Service (DDoS) attack based on flow model and flow detection is presented. The proposed approach can protect targets from DDoS attacking, and allow targets to provide good service to legitimate traffic under DDoS attacking, with fast reaction. This approach adopts the technique of dynamic comb filter, yields a low level of false positives of less than 1.5%,drops similar percentage of good traffic, about 1%, and passes neglectable percentage of attack bandwidth to the victim, less than 1.5%. The prototype of commercial product, D-fighter, is developed by implementing this proposed approach on Intel network processor platform IXP 1200.

  10. Recovery of infrastructure networks after localised attacks

    Science.gov (United States)

    Hu, Fuyu; Yeung, Chi Ho; Yang, Saini; Wang, Weiping; Zeng, An

    2016-04-01

    The stability of infrastructure network is always a critical issue studied by researchers in different fields. A lot of works have been devoted to reveal the robustness of the infrastructure networks against random and malicious attacks. However, real attack scenarios such as earthquakes and typhoons are instead localised attacks which are investigated only recently. Unlike previous studies, we examine in this paper the resilience of infrastructure networks by focusing on the recovery process from localised attacks. We introduce various preferential repair strategies and found that they facilitate and improve network recovery compared to that of random repairs, especially when population size is uneven at different locations. Moreover, our strategic repair methods show similar effectiveness as the greedy repair. The validations are conducted on simulated networks, and on real networks with real disasters. Our method is meaningful in practice as it can largely enhance network resilience and contribute to network risk reduction.

  11. CASE STUDY OF SQL INJECTION ATTACKS

    OpenAIRE

    Sonakshi*, Rakesh Kumar, Girdhar Gopal

    2016-01-01

    Today, most of the web applications are associated with database at back-end so there are possibilities of SQL injection attacks (SQLIA) on it. A number of preventive measures have also been discovered by various researchers to overcome this attack, but which measure is more convenient and provides fast access to application without compromising the security is also a major concern nowadays. This paper provides a clear distinction among different types of SQLIAs and how these can be performed...

  12. Early Detection of SQL Injection Attacks

    Directory of Open Access Journals (Sweden)

    Hossain Shahriar

    2013-07-01

    Full Text Available SQL Injection (SQLI is a common vulnerability found in web applications.The starting point of SQLIattack is the client-side (browser. If attack inputs can be detected early at the browse side, then it could bethwarted early by not forwarding the malicious inputs to the server-side for further processing.This paperpresents a client-side approach to detect SQLI attacks1. The client-side accepts shadow SQL queries fromthe server-side and checks any deviation betweenshadow queries with dynamic queries generated withuser supplied inputs. We measure the deviation of shadow query and dynamic query based on conditionalentropy metrics and propose four metrics in this direction. We evaluate the approach with three PHPapplications containing SQLI vulnerabilities. The evaluation results indicate that our approach can detectwell-known SQLI attacks early at the client-side and impose negligible overhead.

  13. Power analysis attacks revealing the secrets of smart cards

    CERN Document Server

    Mangard, Stefan; Popp, Thomas

    2008-01-01

    A comprehensive treatment of power analysis attacks and countermeasures. Based on the principle that the only way to defend against power analysis attacks is to understand them, this book explains how power analysis attacks work. It discusses simple and differential power analysis as well as advanced techniques like template attacks.

  14. Effect of migraine attacks on paracetamol absorption.

    OpenAIRE

    Tokola, R A; Neuvonen, P J

    1984-01-01

    The absorption of effervescent paracetamol (1000 mg) was investigated in nine female patients during a migraine attack and in the same patients when headache free. Migraine attack decreased (P less than 0.05) the areas under the serum paracetamol concentration-time curves (AUC) of 0-2 h, 0-4 h and 0-6 h and the peak serum concentration. The severity of nausea correlated significantly with the decrease in the AUC values. Our results support findings of delayed gastric emptying in migraine atta...

  15. Panic Attack or Heart Attack?

    Science.gov (United States)

    Panic Attack or Heart Attack? Diagnosing heart disease in women A Healthy Hearts Guide ® Heart disease in women is often mistaken for panic attack with shortness of breath, anxiety, palpitations and indigestion. ...

  16. Chemical Attack of Malaysian Pozzolans Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Hilton Ahmad

    2011-09-01

    Full Text Available Malaysia produces more than 10 million tonne of by-product from industrial sector per year. As the environmental impact concerns, more than half of the by-product can be recycled to be used as construction materials. One of them is pozzolan, a cement replacing material that can be used to enhance the properties of the concrete. This paper studies the chemical attack to local prozzolans concrete. The parameters studied include weight loss, length change, and residual strength of local pozzolans concrete after been exposed to severe environment. The specimen were tested under normal room temperature, exposed to magnesium sulfate, MgSO4. 2H2O where both sulfate attack and acid attack take place. Two series of pozzolans< which is Pulverized fly ash (PFA and Palm oil fuel ash (POFA were identified. Another series of admixture, Quarry Dust (QD from quarry waste that contain high amount of silica content also been carried out. Each series will study the effect of cement replacement percentage of 5%, 10% and 15%. The parameters were compared to conventional ordinary Portland cement (OPC concrete as control mix. Accelerated testing was conducted at 3, 7, 28, 56 and 90 days. The result shows that the local pozzolans concrete were found to be in good resistance against sulfate attack compared to conventional concrete. Compared to all series conducted, series of PFA replacement gave the best resistance followed by POFA and QD replacement series.

  17. Recovery of human remains after shark attack.

    Science.gov (United States)

    Byard, Roger W; James, Ross A; Heath, Karen J

    2006-09-01

    Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim. PMID:16936505

  18. Managing burn victims of suicide bombing attacks: outcomes, lessons learnt, and changes made from three attacks in Indonesia

    OpenAIRE

    Chim, Harvey; Yew, Woon Si; Song, Colin

    2007-01-01

    Introduction Terror attacks in Southeast Asia were almost nonexistent until the 2002 Bali bomb blast, considered the deadliest attack in Indonesian history. Further attacks in 2003 (Jakarta), 2004 (Jakarta), and 2005 (Bali) have turned terrorist attacks into an ever-present reality. Methods The authors reviewed medical charts of victims evacuated to the Singapore General Hospital (SGH) Burns Centre during three suicide attacks involving Bali (2002 and 2005) and the Jakarta Marriott hotel (200...

  19. Analysis of the SYN Flood DoS Attack

    Directory of Open Access Journals (Sweden)

    Mitko Bogdanoski

    2013-06-01

    Full Text Available The paper analyzes systems vulnerability targeted by TCP (Transmission Control Protocol segments when SYN flag is ON, which gives space for a DoS (Denial of Service attack called SYN flooding attack or more often referred as a SYN flood attack. The effects of this type of attack are analyzed and presented in OPNET simulation environment. Furthermore, the paper presents two anomaly detection algorithms as an effective mechanism against this type of attack. Finally, practical approaches against SYN flood attack for Linux and Windows environment which are followed by are shown.

  20. A Survey of Mobile Ad Hoc Network Attacks

    Directory of Open Access Journals (Sweden)

    PRADIP M. JAWANDHIYA,

    2010-09-01

    Full Text Available Security is an essential requirement in mobile ad hoc network (MANETs. Compared to wired networks, MANETs are more vulnerable to security attacks due to the lack of a trusted centralized authority and limited resources. Attacks on ad hoc networks can be classified as passive and active attacks, depending on whether the normal operation of the network is disrupted or not. In this paper, we are describing the all prominent attacks described in literature in a consistent manner to provide a concise comparison on attack types. To the best of our knowledge, this is the first paper that studies all the existing attacks on MANETs.

  1. Framework of SQL Injection Attack

    OpenAIRE

    Patwari, Neha; Bhurani, Parvati

    2012-01-01

    With the changing demographics of globalization, the emergence and prevalence of web application have acquired a central and pivotal role in the domains of technology and advancements. It thus becomes imperative to probe deeply into the architecture, significance and different facets of usages. Web applications enclose the functioning between a user and the services provided by the server, which contains a database as its backend. The user can access the required information through sending a...

  2. Incidence of Fungal attack on Aircraft Fuselage

    Directory of Open Access Journals (Sweden)

    H. M. Dayal

    1968-10-01

    Full Text Available Incidence of fungal attack on the fuselage of a few Vampire aircraft has been observed. The fungus isolated from the infected regions has been tentatively indentified as TorulaSp. Laboratory experiments have revealed that within four weeks this fungus causes about 44 percent loss in the tensile strength of the brich plywood used in the manufacture of the fuselage of the aircraft.

  3. Towards a translational model of panic attacks

    OpenAIRE

    Luiz Carlos Schenberg

    2010-01-01

    About 20 years ago, Deakin and Graeff proposed that whereas generalized anxiety disorder is produced by the overactivity of 5-HT excitatory projections from dorsal raphe nucleus to the areas of prefrontal cortex and amygdala which process distal threat, panic attacks are a dysfunction of 5-HT inhibitory projections from dorsal raphe nucleus to the dorsal periaqueductal gray matter, thereby releasing the responses to proximal threat, innate fear or anoxia. Besides, they suggested that the decr...

  4. An Analysis of Various Attacks in MANET

    OpenAIRE

    M.Udhayamoorthi; C. Senthilkumar; Dr S. Karthik; Dr. T.Kalaikumaran

    2014-01-01

    An Ad-hoc network is a self-organized network, without a central coordinator, and which frequently changes its topology. According to the perspective of our paper, we try to connect the current status of computers era to adhoc networking. As adhoc networks has been unleashing several updated technologies, it is the most growing area in the field of networks in information and communication Engineering has ever seen .we start with area introduction, deeply reviewed about the various attacks es...

  5. Defense and attack of complex and dependent systems

    International Nuclear Information System (INIS)

    A framework is constructed for how to analyze the strategic defense of an infrastructure subject to attack by a strategic attacker. Merging operations research, reliability theory, and game theory for optimal analytical impact, the optimization program for the defender and attacker is specified. Targets can be in parallel, series, combined series-parallel, complex, k-out-of-n redundancy, independent, interdependent, and dependent. The defender and attacker determine how much to invest in defending versus attacking each of multiple targets. A target can have economic, human, and symbolic values, subjectively assessed by the defender and attacker. A contest success function determines the probability of a successful attack on each target, dependent on the investments by the defender and attacker into each target, and on characteristics of the contest. The defender minimizes the expected damage plus the defense costs. The attacker maximizes the expected damage minus the attack costs. Each agent is concerned about how his investments vary across the targets, and the impact on his utilities. Interdependent systems are analyzed where the defense and attack on one target impacts all targets. Dependent systems are analyzed applying Markov analysis and repeated games where a successful attack on one target in the first period impacts the unit costs of defense and attack, and the contest intensity, for the other target in the second period.

  6. Mitigation of Malicious Attacks on Networks

    CERN Document Server

    Schneider, Christian M; Andrade, Jose S; Havlin, Shlomo; Herrmann, Hans J; 10.1073/pnas.1009440108

    2011-01-01

    Terrorist attacks on transportation networks have traumatized modern societies. With a single blast, it has become possible to paralyze airline traffic, electric power supply, ground transportation or Internet communication. How and at which cost can one restructure the network such that it will become more robust against a malicious attack? We introduce a unique measure for robustness and use it to devise a method to mitigate economically and efficiently this risk. We demonstrate its efficiency on the European electricity system and on the Internet as well as on complex networks models. We show that with small changes in the network structure (low cost) the robustness of diverse networks can be improved dramatically while their functionality remains unchanged. Our results are useful not only for improving significantly with low cost the robustness of existing infrastructures but also for designing economically robust network systems.

  7. Robustness of Complex Networks against Attacks Guided by Damage

    CERN Document Server

    Wang, Hui; Xu, Xiaomin; Xiao, Yanghua; Wang, Wei

    2011-01-01

    Extensive researches have been dedicated to investigating the performance of real networks and synthetic networks against random failures or intentional attack guided by degree (degree attack). Degree is one of straightforward measures to characterize the vitality of a vertex in maintaining the integrity of the network but not the only one. Damage, the decrease of the largest component size that was caused by the removal of a vertex, intuitively is a more destructive guide for intentional attack on networks since the network functionality is usually measured by the largest component size. However, it is surprising to find that little is known about behaviors of real networks or synthetic networks against intentional attack guided by damage (damage attack), in which adversaries always choose the vertex with the largest damage to attack. In this article, we dedicate our efforts to understanding damage attack and behaviors of real networks as well as synthetic networks against this attack. To this end, existing ...

  8. Concrete Deterioration under Alternate Action of Carbonation and Sulfate Attack

    Directory of Open Access Journals (Sweden)

    Fenglan Li

    2013-11-01

    Full Text Available By micro- and macro-observations, the study reveals the deterioration mechanisms of concrete under alternate action of carbonation and sodium sulfate solution attack (C-SA comparied with the single sodium sulfate solution attack (SA. The studies indicate that in both cases, the main attack product is ettringite, some gypsum is checked only in the first layer of case SA, the thaumasite form of sulfate attack is not initiated in case C-SA. Compared with the single sodium sulfate solution attack, although the carbonation layer mitigates the extent of sulfate attack in limited exposure period, the alternate action of carbonation and sulfate attack still leads to strength degradation to some extent. The effect of carbonation on sulfate attack for longer exposure period deserves further research.

  9. Extensions of the Cube Attack Based on Low Degree Annihilators

    Science.gov (United States)

    Zhang, Aileen; Lim, Chu-Wee; Khoo, Khoongming; Wei, Lei; Pieprzyk, Josef

    At Crypto 2008, Shamir introduced a new algebraic attack called the cube attack, which allows us to solve black-box polynomials if we are able to tweak the inputs by varying an initialization vector. In a stream cipher setting where the filter function is known, we can extend it to the cube attack with annihilators: By applying the cube attack to Boolean functions for which we can find low-degree multiples (equivalently annihilators), the attack complexity can be improved. When the size of the filter function is smaller than the LFSR, we can improve the attack complexity further by considering a sliding window version of the cube attack with annihilators. Finally, we extend the cube attack to vectorial Boolean functions by finding implicit relations with low-degree polynomials.

  10. Understand Your Risk of Heart Attack

    Science.gov (United States)

    ... Stroke More Understand Your Risks to Prevent a Heart Attack Updated:Aug 2,2016 Knowledge is power, so ... medication. This content was last reviewed June 2016. Heart Attack • Home • About Heart Attacks Acute Coronary Syndrome (ACS) • ...

  11. A Formal Classification of Internet Banking Attacks and Vulnerabilities

    Directory of Open Access Journals (Sweden)

    Laerte Peotta

    2011-02-01

    Full Text Available A formal classification of attacks and vulnerabilities that affect current internet banking systems is presented along with two attacks which demonstrate the insecurity of such systems. Based ona thoroughanalysis of current security models, we propose a guidelines for designing secure internet banking systems which are not affected by the presented attacks and vulnerabilities.

  12. A Review of Man-in-the-Middle Attacks

    OpenAIRE

    Gangan, Subodh

    2015-01-01

    This paper presents a survey of man-in-the-middle (MIM) attacks in communication networks and methods of protection against them. In real time communication, the attack can in many situations be discovered by the use of timing information. The most common attacks occur due to Address Resolution Protocol (ARP) cache poisoning, DNS spoofing, session hijacking, and SSL hijacking.

  13. Methods of Identifying and Preventing SQL Attacks

    Directory of Open Access Journals (Sweden)

    Bojken Shehu

    2012-11-01

    Full Text Available The paper begins by identifying the organizations which are vulnerable to the SQL attack referred to as an SQL injection attack. The term SQL injection attack is defined and a diagram is used to illustrate the way that attack occurs. In another section, the paper identifies the methods used to detect an attack to SQL, whereby the techniques are discussed extensively using relevant diagrams for illustration. The other sections cover the preventive methods, where the methods are also discussed with an illustration using diagrams.

  14. Tests of Aerodynamically Heated Multiweb Wing Structures in a Free Jet at Mach Number 2: Five Aluminum-Alloy Models of 20-Inch Chord with 0.064-Inch-Thick Skin, 0.025-Inch-Thick Webs, and Various Chordwise Stiffening at 2 deg Angle of Attack

    Science.gov (United States)

    Trussell, Donald H.; Thomson, Robert G.

    1960-01-01

    An experimental study was made on five 2024-T3 aluminum-alloy multiweb wing structures (MW-2-(4), MW-4-(3), mw-16, MW-17, and MW-18), at a Mach number of 2 and an angle of attack of 2 deg under simulated supersonic flight conditions. These models, of 20-inch chord and semi-span and 5-percent-thick circular-arc airfoil section, were identical except for the type and amount of chordwise stiffening. One model with no chordwise ribs between root and tip bulkhead fluttered and failed dynamically partway through its test. Another model with no chordwise ribs (and a thinner tip bulkhead) experienced a static bending type of failure while undergoing flutter. The three remaining models with one, two, or three chordwise ribs survived their tests. The test results indicate that the chordwise shear rigidity imparted to the models by the addition of even one chordwise rib precludes flutter and subsequent failure under the imposed test conditions. This paper presents temperature and strain data obtained from the tests and discusses the behavior of the models.

  15. Unified communications forensics anatomy of common UC attacks

    CERN Document Server

    Grant, Nicholas Mr

    2013-01-01

    Unified Communications Forensics: Anatomy of Common UC Attacks is the first book to explain the issues and vulnerabilities and demonstrate the attacks, forensic artifacts, and countermeasures required to establish a secure (UC) environment. This book is written by leading UC experts Nicholas Grant and Joseph W. Shaw II and provides material never before found on the market, including: analysis of forensic artifacts in common UC attacks an in-depth look at established UC technologies and attack exploits hands-on understanding of UC attack vectors and associated countermeasures

  16. Robustness of correlated networks against propagating attacks

    CERN Document Server

    Hasegawa, Takehisa; Nemoto, Koji

    2012-01-01

    We investigate robustness of correlated networks against propagating attacks modeled by a susceptible-infected-removed model. By Monte-Carlo simulations, we numerically determine the first critical infection rate, above which a global outbreak of disease occurs, and the second critical infection rate, above which disease disintegrates the network. Our result shows that correlated networks are robust compared to the uncorrelated ones, regardless of whether they are assortative or disassortative. This behavior is related to the layered network structure inevitably generated by a rewiring procedure we adopt to realize correlated networks.

  17. Activity Modelling and Comparative Evaluation of WSN MAC Security Attacks

    DEFF Research Database (Denmark)

    Pawar, Pranav M.; Nielsen, Rasmus Hjorth; Prasad, Neeli R.;

    2012-01-01

    Applications of wireless sensor networks (WSNs) are growing tremendously in the domains of habitat, tele-health, industry monitoring, vehicular networks, home automation and agriculture. This trend is a strong motivation for malicious users to increase their focus on WSNs and to develop...... and initiate security attacks that disturb the normal functioning of the network in a severe manner. Such attacks affect the performance of the network by increasing the energy consumption, by reducing throughput and by inducing long delays. Of all existing WSN attacks, MAC layer attacks are considered....... The second aim of the paper is to simulate these attacks on hybrid MAC mechanisms, which shows the performance degradation of aWSN under the considered attacks. The modelling and implementation of the security attacks give an actual view of the network which can be useful in further investigating secure...

  18. PERFORMANCE EVALUATION OF WIRELESS SENSOR NETWORK UNDER HELLO FLOOD ATTACK

    Directory of Open Access Journals (Sweden)

    Mohammad Abdus Salam

    2016-03-01

    Full Text Available Wireless sensor network (WSN is highly used in many fields. The network consists of tiny lightweight sensor nodes and is largely used to scan or detect or monitor environments. Since these sensor nodes are tiny and lightweight, they put some limitations on resources such as usage of power, processing given task, radio frequency range. These limitations allow network vulnerable to many different types of attacks such as hello flood attack, black hole, Sybil attack, sinkhole, and many more. Among these attacks, hello flood is one of the most important attacks. In this paper,we have analyzed the performance of hello flood attack and compared the network performance as number of attackers increases. Network performance is evaluated by modifying the ad-hoc on demand distance vector (AODV routing protocol by using NS2 simulator. It has been tested under different scenarios like no attacker, single attacker, and multiple attackers to know how the network performance changes. The simulation results show that as the number of attackers increases the performance in terms of throughput and delay changes.

  19. Optimal counterterrorism and the recruitment effect of large terrorist attacks

    DEFF Research Database (Denmark)

    Jensen, Thomas

    2011-01-01

    We analyze a simple dynamic model of the interaction between terrorists and authorities. Our primary aim is to study optimal counterterrorism and its consequences when large terrorist attacks lead to a temporary increase in terrorist recruitment. First, we show that an increase in counterterrorism...... makes it more likely that terrorist cells plan small rather than large attacks and therefore may increase the probability of a successful attack. Analyzing optimal counterterrorism we see that the recruitment effect makes authorities increase the level of counterterrorism after large attacks. Therefore......, in periods following large attacks a new attack is more likely to be small compared to other periods. Finally, we analyze the long-run consequences of the recruitment effect. We show that it leads to more counterterrorism, more small attacks, and a higher sum of terrorism damage and counterterrorism...

  20. On the security of gyrator transform-based image encryption by chosen-plaintext attack

    Science.gov (United States)

    Sang, Jun; Alam, Mohammad S.; Cai, Bin

    2016-04-01

    For the gyrator transform-based image encryption, besides the random operations, the rotation angles used in the gyrator transforms are also taken as the secret keys, which makes such cryptosystems to be more secure. To analyze the security of such cryptosystems, one may start from analyzing the security of a single gyrator transform. In this paper, the security of the gyrator transform-based image encryption by chosen-plaintext attack was discussed in theory. By using the impulse functions as the chosen-plaintext, it was concluded that: (1) For a single gyrator transform, by choosing a plaintext, the rotation angle can be obtained very easily and efficiently; (2) For image encryption with a single random phase encoding and a single gyrator transform, it is hard to find the rotation angle directly with a chosen-plaintext attack. However, assuming the value of one of the elements in the random phase mask is known, the rotation angle can be obtained very easily with a chosen-plaintext attack, and the random phase mask can also be recovered. Furthermore, by exhaustively searching the value of one of the elements in the random phase mask, the rotation angle as well as the random phase mask may be recovered. By obtaining the relationship between the rotation angle and the random phase mask for image encryption with a single random phase encoding and a single gyrator transform, it may be useful for further study on the security of the iterative random operations in the gyrator transform domains.

  1. Frequency characteristics of breakdown vortices over delta wings with small amplitude oscillation at the high angle of attack%大迎角下小振幅振荡三角翼破裂涡的频率特性

    Institute of Scientific and Technical Information of China (English)

    张明禄; 刘绍辉; 吕志咏

    2009-01-01

    Experiments of dynamic unsteady pressure measurement and hot film velocity measurement with the small amplitude oscillation delta wings were carried out in a water channel and a wind tunnel respec-tively in order to investigate the influence of the nondimensional oscillation frequency n on the frequency char-acteristics of leading-edge vortices over delta wings. Power spectral analysis of pressure signal measured in the wind tunnel shows that at n =0.018~0.036, which is close to the oscillation frequency of vortex breakdown point, resonant phenomenon will happen and oscillatory energy will be largely enhanced. Power spectral analy-sis of velocity signal measured in the water channel shows that at n =0. 8~1. 38, which is close to the propa-gation frequency of spiral wave, the vortex breakdown point moves towards trailing edge, and therefore break-down of vortices will be delayed and the dominant frequency will be increased.%在风洞和水洞中分别进行了小振幅振荡三角翼的动态测压和热膜测速实验,目的是研究振荡的无量纲频率n对于三角翼前缘涡的频率特性的影响.对风洞中测得的压力数据进行频谱分析,发现n值在0.018~0.036时,即与三角翼翼面上涡破裂点的振荡频率接近时,会发生耦合现象,使振动能量明显加强;对水洞中测得的速度数据进行频谱分析,则发现n在0.8~1.4的范围内,即与螺旋波的传播频率接近时,三角翼的振荡会使涡破裂点向后缘移动,延缓了涡的破裂,使螺旋波频率增大.

  2. Effectiveness and detection of denial of service attacks in Tor

    OpenAIRE

    Danner, Norman; DeFabbia-Kane, Sam; Krizanc, Danny; Liberatore, Marc

    2011-01-01

    Tor is currently one of the more popular systems for anonymizing near real-time communications on the Internet. Recently, Borisov et al. proposed a denial of service based attack on Tor (and related systems) that significantly increases the probability of compromising the anonymity provided. In this paper, we analyze the effectiveness of the attack using both an analytic model and simulation. We also describe two algorithms for detecting such attacks, one deterministic and proved correct, the...

  3. Effectiveness and detection of denial of service attacks in Tor

    CERN Document Server

    Danner, Norman; Krizanc, Danny; Liberatore, Marc

    2011-01-01

    Tor is currently one of the more popular systems for anonymizing near real-time communications on the Internet. Recently, Borisov et al. proposed a denial of service based attack on Tor (and related systems) that significantly increases the probability of compromising the anonymity provided. In this paper, we analyze the effectiveness of the attack using both an analytic model and simulation. We also describe two algorithms for detecting such attacks, one deterministic and proved correct, the other probabilistic and verified in simulation.

  4. Public knowledge of heart attack symptoms in Beijing residents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-tan; HU Da-yi; YANG Jin-gang; ZHANG Shou-yan; ZHANG Xin-quan; LIU Shu-shan

    2007-01-01

    Background Definitive treatment for heart attack is early reperfusion with either angioplasty or thrombolytic therapy,and the benefit is strictly time-dependent. Patient outcomes are improved with either therapy when initiated as soon as possible. Recognition of heart attack symptoms is logically tied to taking action to receive prompt emergency care.Inadequate knowledge of heart attack symptoms may prolong delay. The purpose of this study was to document knowledge about heart attack symptoms in Beijing residents and to identify the characteristics associated with increased knowledge of heart attack.Methods A structured survey was conducted in 18 communities in Beijing from March 1 through June 10 in 2006.Addresses and participants were selected randomly following a stratification. The survey was designed to collect knowledge of heart attack symptoms from sampled adults in each community.Results A total of 4627 respondents completed the questionnaires correctly, and 50.29% of them were female. Totally 64.15% of the respondents reported chest pain or discomfort (common symptoms) as a symptom of heart attack; 75.38% reported at least one of the following eight symptoms as a symptom of heart attack: back pain, shortness of breath, arm pain or numbness, nausea or vomiting, neck, jaw or shoulder pain, epigastric pain, sweating, weakness (less common symptoms); 20.36% correctly reported four or more heart attack symptoms, only 7.4% knew all the correct heart attack symptoms, and 28.94% knew about reperfusion therapy for heart attack; 31.7% reported to call 120 or 999 while having a heart attack themselves; however 89.6% reported to call 120 or 999 when someone else is suffering from a heart attack. Very old persons and those with health insurance coverage, high education level, high household income, longer living in Beijing and previous experience with heart disease had greater knowledge of heart attack symptoms.Conclusions Public knowledge of common heart attack

  5. Calculations of the Wigner angle

    International Nuclear Information System (INIS)

    Two new methods to determine Wigner's angle in special relativity are presented. The first one consists in calculating the angle between the compositions u-bar x ν-bar and ν-bar x u-bar of the two non-collinear velocities u-bar and ν-bar. In another method we introduce a generalization in the complex plane of Einstein's addition law of parallel velocities. (author)

  6. 原发性闭角型青光眼单侧急性发作对侧眼激光虹膜周边切除术后随访研究%Follow-up of laser peripheral iridotomy in fellow eyes with unilateral acute attack of primary angle closure glaucoma

    Institute of Scientific and Technical Information of China (English)

    张海涛; 杨华; 徐英英

    2011-01-01

    Background Laser peripheral iridotomy(LPI) is used as the primary therapy for the eyes at risk of angle closure.But there are still 28% eyes with primary angle closure suspect occur angle closure within 2 years after LPI.It is necessary to explore the associated factors of the efficacy of LPI.Objective The aim of this study was to explore the changes of intraocular pressure(IOP) and anterior chamber angle in the fellow eyes of patients with unilateral acute attack of primary angle closure glaucoma (PACG) and analyze the relevant factors influencing the successful rate of LPI.Methods Eighty-seven fellow eyes received LPI from 87 patients with unilateral acute attack of PACG were included in this study and retrospectively analyzed.The IOP and gonioscopy were performed before and 1 week,3,6,9,12 months after LPI.Successful signs of LPI were defined as an IOP 6-21mmHg without any anti-glaucoma medication,none of glaucomatous neuropathy and the coincident visual field loss,and no need of additional glaucomatous medication or surgery.This study was approved by Ethic Committee of the First Hospital of Xinxiang Medical College,and written informed consent was obtained from each patient.Results Seventy-nine eyes of 79 cases finished the medical visit throughout the follow-up duration with the age 61.4±0.4 years and 33(41.8%) males and 46(58.2%) females.The mean IOP was lowed in various time points after LPI in comparison with before operation with the general difference among different time visiting groups(F=4.056,P<0.01).Shaffer grade was increased in superior,temporal and nasal quadrants and significant differences were found between 1 week group,3 months group or 6 months group and before operation group (P<0.05).LPI lessened the range of appositional angle closure (AAC) in postoperative 1 week group and 3 months group compared with pre-operative group (P<0.05),but no statistically significant reduce was seen in range of AAC from 6 months through 12 months after

  7. The Impact of Imperfect Information on Network Attack

    CERN Document Server

    Melchionna, Andrew; Squires, Shane; Antonsen, Thomas M; Ott, Edward; Girvan, Michelle

    2014-01-01

    This paper explores the effectiveness of network attack when the attacker has imperfect information about the network. For Erd\\H{o}s-R\\'enyi networks, we observe that dynamical importance and betweenness centrality-based attacks are surprisingly robust to the presence of a moderate amount of imperfect information and are more effective compared with simpler degree-based attacks even at moderate levels of network information error. In contrast, for scale-free networks the effectiveness of attack is much less degraded by a moderate level of information error. Furthermore, in the Erd\\H{o}os-R\\'enyi case the effectiveness of network attack is much more degraded by missing links as compared with the same number of false links.

  8. Performance Analysis of Manet Before and After Black Hole Attack

    Directory of Open Access Journals (Sweden)

    Ms.Heena Bhalla

    2012-01-01

    Full Text Available A Mobile ad-hoc network is a temporary network set up by wireless mobile computers (or nodes moving arbitrary in the places that have no network infrastructure. Due to security vulnerabilities of the routing protocols, wireless ad-hoc networks are unprotected to attacks of the malicious nodes. One of the prominent attacks is the Black Hole Attack which absorbs all data packets in the network. Since the data packets do not reach the destination node on account of this attack, data loss will occur. In this paper we simulated MANETs with and without Black Hole to study the effects of Black hole attack on network performance. Because of Black Hole Attack the average packet drop increased form 0.25% to 90.69% . The throughput of the network decreased 93.56% due to Black Hole effect.

  9. Efficient Detection of Sybil attack Based on Cryptography in Vanet

    Directory of Open Access Journals (Sweden)

    Mina Rahbari

    2011-12-01

    Full Text Available Vehicular communications play a substantial role in providing safety transportation by means of safetymessage exchange. Researchers have proposed several solutions for securing safety messages. Protocols based on a fixed key infrastructure are more efficient in implementation and maintain stronger security in comparison with dynamic structures. The purpose of this paper present a method based on a fixed keyinfrastructure for detection impersonation attack, in other words, Sybil attack, in the vehicular adhoc network. This attack, puts a great impact on performance of the network. The proposed method, using an cryptography mechanism to detection Sybil attack. Finally, using Mat lab simulator the results of this approach are reviewed, This method it has low delay for detection Sybil attack, because most operations are done in Certification Authority, so this proposed schema is a efficient method for detection Sybil attack.

  10. Efficient Detection of Sybil Attack Based on Cryptography in Vanet

    CERN Document Server

    Rahbari, Mina

    2011-01-01

    Vehicular communications play a substantial role in providing safety transportation by means of safety message exchange. Researchers have proposed several solutions for securing safety messages. Protocols based on a fixed key infrastructure are more efficient in implementation and maintain stronger security in comparison with dynamic structures. The purpose of this paper present a method based on a fixed key infrastructure for detection impersonation attack, in other words, Sybil attack, in the vehicular ad hoc network. This attack, puts a great impact on performance of the network. The proposed method, using an cryptography mechanism to detection Sybil attack. Finally, using Mat lab simulator the results of this approach are reviewed, This method it has low delay for detection Sybil attack, because most operations are done in Certification Authority, so this proposed schema is a efficient method for detection Sybil attack.

  11. Cyber Attacks and the Use of Force in International Law

    OpenAIRE

    Valo, Janne

    2014-01-01

    The thesis reviews the issue of cyber attacks and international law in terms of jus ad bellum, the law concerning the recourse to force by states. The thesis takes the view that the existing rules on the use of force, namely Articles 2(4) and 51 of the United Nations Charter and the corresponding rules of customary international law apply to attacks regardless of the way they are carried out and thus, they apply to cyber attacks as well. Two central examples of different kinds of cyber attack...

  12. An Indistinguishability Model for Evaluating Diverse Classes of Phishing Attacks and Quantifying Attack Efficacy

    Directory of Open Access Journals (Sweden)

    Narasimha Shashidhar

    2015-07-01

    Full Text Available Phishing is a growing threat to Internet users and causes billions of dollars in damage every year. While there are a number of research articles that study the tactics, techniques and procedures employed by phishers in the literature, in this paper, we present a theoretical yet practical model to study this menacing threat in a formal manner. While it is common folklore knowledge that a successful phishing attack entails creating messages that are indistinguishable from the natural, expected messages by the intended victim, this concept has not been formalized. Our model attempts to capture a phishing attack in terms of this indistinguishability between the natural and phishing message probability distributions. We view the actions performed by a phisher as an attempt to create messages that are indistinguishable to the victim from that of “normal” messages. To the best of our knowledge, this is the first study that places phishing on a concrete theoretical framework and offers a new perspective to analyze this threat. We propose metrics to analyze the success probability of a phishing attack taking into account the input used by a phisher and the work involved in creating deceptive email messages. Finally, we study and apply our model to a new class of phishing attacks called collaborative spear phishing that is gaining momentum. Recent examples include Operation Woolen-Goldfish in 2015, Rocket Kitten in 2014 and Epsilon email breach in 2011. We point out fundamental flaws in the current email-based marketing business model which enables such targeted spear phishing collaborative attacks. In this sense, our study is very timely and presents new and emerging trends in phishing.

  13. PERFORMANCE EVALUATION OF WIRELESS SENSOR NETWORK UNDER HELLO FLOOD ATTACK

    OpenAIRE

    Mohammad Abdus Salam; Nayana Halemani

    2016-01-01

    Wireless sensor network (WSN) is highly used in many fields. The network consists of tiny lightweight sensor nodes and is largely used to scan or detect or monitor environments. Since these sensor nodes are tiny and lightweight, they put some limitations on resources such as usage of power, processing given task, radio frequency range. These limitations allow network vulnerable to many different types of attacks such as hello flood attack, black hole, Sybil attack, sinkhole, and m...

  14. Neural network classifier of attacks in IP telephony

    Science.gov (United States)

    Safarik, Jakub; Voznak, Miroslav; Mehic, Miralem; Partila, Pavol; Mikulec, Martin

    2014-05-01

    Various types of monitoring mechanism allow us to detect and monitor behavior of attackers in VoIP networks. Analysis of detected malicious traffic is crucial for further investigation and hardening the network. This analysis is typically based on statistical methods and the article brings a solution based on neural network. The proposed algorithm is used as a classifier of attacks in a distributed monitoring network of independent honeypot probes. Information about attacks on these honeypots is collected on a centralized server and then classified. This classification is based on different mechanisms. One of them is based on the multilayer perceptron neural network. The article describes inner structure of used neural network and also information about implementation of this network. The learning set for this neural network is based on real attack data collected from IP telephony honeypot called Dionaea. We prepare the learning set from real attack data after collecting, cleaning and aggregation of this information. After proper learning is the neural network capable to classify 6 types of most commonly used VoIP attacks. Using neural network classifier brings more accurate attack classification in a distributed system of honeypots. With this approach is possible to detect malicious behavior in a different part of networks, which are logically or geographically divided and use the information from one network to harden security in other networks. Centralized server for distributed set of nodes serves not only as a collector and classifier of attack data, but also as a mechanism for generating a precaution steps against attacks.

  15. Non-harmful insertion of data mimicking computer network attacks

    Science.gov (United States)

    Neil, Joshua Charles; Kent, Alexander; Hash, Jr, Curtis Lee

    2016-06-21

    Non-harmful data mimicking computer network attacks may be inserted in a computer network. Anomalous real network connections may be generated between a plurality of computing systems in the network. Data mimicking an attack may also be generated. The generated data may be transmitted between the plurality of computing systems using the real network connections and measured to determine whether an attack is detected.

  16. Flooding Distributed Denial of Service Attacks-A Review

    Directory of Open Access Journals (Sweden)

    Khadijah W.M. Ghazali

    2011-01-01

    Full Text Available Problem statement: Flaws either in users’ implementation of a network or in the standard specification of protocols has resulted in gaps that allow various kinds of network attack to be launched. Of the kinds of network attacks, denial-of-service flood attacks have caused the most severe impact. Approach: This study reviews recent researches on flood attacks and their mitigation, classifying such attacks as either high-rate flood or low-rate flood. Finally, the attacks are compared against criteria related to their characteristics, methods and impacts. Results: Denial-of-service flood attacks vary in their rates, traffic, targets, goals and impacts. However, they have general similarities that are the methods used are flooding and the main purpose is to achieve denial of service to the target. Conclusion/Recommendations: Mitigation of the denial-of-service flood attacks must correspond to the attack rates, traffic, targets, goals and impacts in order to achieve effective solution.

  17. Fake BTS Attacks of GSM System on Software Radio Platform

    OpenAIRE

    Yubo Song; Kan Zhou; Xi Chen

    2012-01-01

    The 2G GSM communication system only provides one-way authentication mechanism which just authenticate the identities of mobile users. As we know, this is not resistant to fake BTS attack. But for the huge cost for building a fake BTS before, this kind of attack were not really implemented before. This paper presents an implement of fake BTS based on software radio technologies. Furthermore, this paper discusses two types of fake BTS attacks on our software radio platform. The first attack is...

  18. Fake BTS Attacks of GSM System on Software Radio Platform

    Directory of Open Access Journals (Sweden)

    Yubo Song

    2012-02-01

    Full Text Available The 2G GSM communication system only provides one-way authentication mechanism which just authenticate the identities of mobile users. As we know, this is not resistant to fake BTS attack. But for the huge cost for building a fake BTS before, this kind of attack were not really implemented before. This paper presents an implement of fake BTS based on software radio technologies. Furthermore, this paper discusses two types of fake BTS attacks on our software radio platform. The first attack is IMSI/IMEI catch attack, which can get the mobile phone’s IMSI and IMEI. With this information, attacker can got the track of the man with this phone. The second attack is selective jamming attack. After get the IMSI and IMEI of the mobile phone, the attackers can decide whether the mobile phone is blocked or not. We will analyze the GSM protocol which is relevant to the interception system and later present the performance of such a system by real tests and demonstrate its feasibility.

  19. Performance analysis of black hole attacks in geographical routing MANET

    Directory of Open Access Journals (Sweden)

    H.J Shanthi

    2014-10-01

    Full Text Available The MANET (Mobile Adhoc Network is vulnerable to several types of attacks. The most commonly classified attack is black hole attack, which is carried by single or multiple attackers, advertising itself of having a short fresh route to transmit data. The aim is to ensure security against the black hole attack and analyze the performance in geographical routing. The simple method is to send data as small blocks instead of entire data. The traffic is monitored independently in its neighborhood. The mechanism uses geographic information to detect variance in neighbor relations and node movements. We analyze the black hole attack in two popular location based protocol LAR and DREAM. It provides the stimulation study of black hole attack with the minimum attacker and also provides analysis on the parameters such as throughput, packet delivery and delay done with OMNET++ simulator. The simulation results show that packet loss increases and throughput decreases in the network with a black hole node in geographical routing. The proposed mechanism can be combined with existent routing protocols to defend against black hole attacks.

  20. Prevention Of WormholeAttacks In Geographic Routing Protocol

    Directory of Open Access Journals (Sweden)

    E.Poornima,

    2011-01-01

    Full Text Available As mobile ad hoc network applications are deployed, security emerges as a central requirement..Position aided routing protocols can offer a significant performance increase over traditional ad hoc routing protocols. Boundary State Routing (BSR is a geographic routing protocol which routes the data using the location of the nodes. Geographic routing protocols are known to be particularly susceptible to attacks.. In this paper we present the possible attacks on BSR protocol. One of the most popular and serious attacks in ad hoc networks is wormhole attack in which two or more colluding attackers record packets at one location, and tunnel them to another location for a replay at that remote location. A wormhole attack is very powerful, and preventing the attack has proven to be very difficult. In this paper, we devise efficient methods to detect and avoid wormhole attacks in the BSR protocol. The first method namely Reverse Routing Scheme (RRS attempts to detect the intrusion action .The second technique namely Authentication of Nodes Scheme (ANS uses cryptographic concepts to detect and prevent wormhole attacks. It not only detects the fake route but also adopts preventive measures against action wormhole nodes from reappearing during routing. The proposed system is designed in Boundary state routing (BSRprotocol and analysis and simulations are performed in network simulator (NS-2.

  1. Variability of clinical features in attacks of migraine with aura

    DEFF Research Database (Denmark)

    Hansen, Jakob M; Goadsby, Peter J; Charles, Andrew C

    2016-01-01

    BACKGROUND: There is significant variability in the clinical presentation of migraine, both among patients, and between attacks in an individual patient. We examined clinical features of migraine with aura in a large group of patients enrolled in a clinical trial, and compared retrospective...... detailed retrospective description of the clinical features of their attacks of migraine. During the trial, clinical symptoms in migraine attacks starting with aura were recorded prospectively in 861 attacks. RESULTS: Retrospectively reported visual aura symptoms were variable and often overlapping; the...... recalling or speaking words. A significant percentage of patients also reported a change in olfaction. There were several inconsistencies between the features of prospectively recorded and retrospectively reported attacks. Headache, nausea, photophobia, and phonophobia were all less common in prospectively...

  2. Prodromes and predictors of migraine attack.

    Science.gov (United States)

    Rossi, Paolo; Ambrosini, Anna; Buzzi, M Gabriella

    2005-01-01

    Premonitory symptoms of migraine include a wide and heterogeneous collection of cognitive, psychic and physical changes preceding and forewarning of an attack by a few hours to 2-3 days. To date, premonitory symptoms have received little attention in the literature, being treated more as a curiosity than as a primary feature of migraine. This paper provides an extensive critical review of this neglected area of migraine research in the light of the recent advances in our understanding of the pathogenetic mechanisms of migraine. Epidemiological and clinical studies that have investigated the premonitory symptoms of migraine lack scientific rigour, producing conflicting results, whilst genetic and pathophysiological investigations are still in their very early stages. There is evidence supporting the idea that premonitory symptoms could be used as a phenotypical marker to identify subgroups of migraineurs which could show correlations with specific clinical expressions of the disease, genotypes, or responses to treatments. Future studies are needed to clarify the clinical, pathophysiological and therapeutic significance of premonitory symptoms. PMID:16483459

  3. Assessment and treatment of nocturnal panic attacks.

    Science.gov (United States)

    Craske, Michelle G; Tsao, Jennie C I

    2005-06-01

    Nocturnal panic (NP), waking from sleep in a state of panic, is a common occurrence among patients with panic disorder, with 44-71% reporting at least one such attack. NP is a non-REM event that is distinct from sleep terrors, sleep apnea, nightmares or dream-induced arousals. This review outlines recent advances in the characterization of NP, as well as current approaches to the assessment and treatment of NP. In contrast to earlier work, more recent studies suggest that patients with NP do not differ from patients without NP on sleep architecture, sleep physiology, self-reported sleep quality and severity of panic disorder. However, more precise measurement of physiological precipitants and features is warranted. Assessment of NP focuses on ruling out other explanations for NP, with differential diagnosis based on interviews, sleep polysomnography and ambulatory recording of sleep. Psychological treatment (cognitive-behavioral therapy) targets misappraisals of anxiety sensations, hyperventilatory response, and conditioned reactions to internal, physical cues. Recent evidence supports the efficacy of this approach, however, controlled studies on pharmacological agents in the treatment of NP are lacking. Research is needed to examine the effects of combined cognitive-behavioral therapy and medications, compared to medication alone in the treatment of NP. PMID:15893248

  4. Is There Anybody There? A Psychodynamic View of Panic Attack.

    Science.gov (United States)

    Rizq, Rosemary

    2002-01-01

    Presents a process analysis of a psychodynamic intervention for a client with panic attacks. Discusses how a psychodynamic understanding of the complex etiology of the client's panic attacks that ultimately produced improved coping skills and a subjective sense of improvement for her. Process analysis is used to illustrate the theoretical base,…

  5. Pareto Efficient Solutions of Attack-Defence Trees

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming

    2015-01-01

    probability or cost of attacks and defences. In case of multiple parameters most analytical methods optimise one parameter at a time, e.g., minimise cost or maximise probability of an attack. Such methods may lead to sub-optimal solutions when optimising conflicting parameters, e.g., minimising cost while...

  6. An Indistinguishability Model for Evaluating Diverse Classes of Phishing Attacks and Quantifying Attack Efficacy

    OpenAIRE

    Narasimha Shashidhar; Lei Chen

    2015-01-01

    Phishing is a growing threat to Internet users and causes billions of dollars in damage every year. While there are a number of research articles that study the tactics, techniques and procedures employed by phishers in the literature, in this paper, we present a theoretical yet practical model to study this menacing threat in a formal manner. While it is common folklore knowledge that a successful phishing attack entails creating messages that are indistinguishable from the natural, expected...

  7. Performance evaluation of DSR Protocol under DoS attack

    Directory of Open Access Journals (Sweden)

    Ms. Trupti Patel

    2012-03-01

    Full Text Available A mobile ad-hoc network (MANET consists of mobile hosts equipped with wireless communication devices. A Mobile Ad hoc Network is a self-organizing, infrastructure less, multi-hop network. The transmission of a mobile host is received by all hosts within its transmission range due to the broadcast nature of wireless communication and unidirectional antenna. If two wireless hosts are out of their transmission ranges in the ad hoc networks, other mobile hosts located between them can forward their message, which effectively builds connected networks among the mobile hosts in the deployed area. One main challenge in design of these networks is their vulnerable nature to security attack. These attacks can be deployed by insider or outsider attacker. Sometime, the node from network can be attacker. This is happen because of mobility of nodes and changing network topology. There are different kind of attacks available in literature and can be implemented on MANET. One of these attacks is Grey Hole attack that has dangerous effect on Mobile Ad-Hoc Network. In this paper, we study the effect of Grey Hole attack on Dynamic Source Routing (DSR protocol in Mobile Ad-Hoc Network.

  8. Effectiveness of the Call in Beach Volleyball Attacking Play

    Directory of Open Access Journals (Sweden)

    Künzell Stefan

    2014-12-01

    Full Text Available In beach volleyball the setter has the opportunity to give her or his hitter a “call”. The call intends that the setter suggests to her or his partner where to place the attack in the opponent’s court. The effectiveness of a call is still unknown. We investigated the women’s and men’s Swiss National Beach Volleyball Championships in 2011 and analyzed 2185 attacks. We found large differences between female and male players. While men called in only 38.4% of attacks, women used calls in 85.5% of attacks. If the male players followed a given call, 63% of the attacks were successful. The success rate of attacks without any call was 55.8% and 47.6% when the call was ignored. These differences were not significant (χ2(2 = 4.55, p = 0.103. In women’s beach volleyball, the rate of successful attacks was 61.5% when a call was followed, 35% for attacks without a call, and 42.6% when a call was ignored. The differences were highly significant (χ2(2 = 23.42, p < 0.0005. Taking into account the findings of the present study, we suggested that the call was effective in women’s beach volleyball, while its effect in men’s game was unclear. Considering the quality of calls we indicate that there is a significant potential to increase the effectiveness of a call.

  9. Strategies and scenarios of CSRF attacks against the CAPTCHA forms

    Directory of Open Access Journals (Sweden)

    Hossein Moradi

    2015-01-01

    Full Text Available In this article, we’ve tried to examine the hypothesis of the robustness of a form by using CAPTCHA against CSRF and login CSRF attacks. Our investigations showed that unlike public opinion, common attacks to bypass CAPTCHAs such as Optical Character Recognition (OCR and 3rd party human attacks are not applicable in the CSRF case and instead, Clickjacking is the most important scenario of CSRF and login CSRF attacks against a secure session-dependent CAPTCHA form. Remember that the Clickjacking is also applicable to bypass the well-known CSRF protections, such as the secret token and the Referer header. Therefore, although the frequent application of CAPTCHA on every page of a website negatively impacts the user experience, but the robustness of a robust session-dependent CAPTCHA against the CSRF and login CSRF attacks is almost the same as the session-dependent security token. Moreover, when a website is using a session-independent or week pattern of CAPTCHA, attackers can bypass the CAPTCHAs and launch the CSRF or login CSRF attacks by using XSS, session hijacking, replay attacks or submitting a random response.

  10. Optimal attack strategy of complex networks based on tabu search

    Science.gov (United States)

    Deng, Ye; Wu, Jun; Tan, Yue-jin

    2016-01-01

    The problem of network disintegration has broad applications and recently has received growing attention, such as network confrontation and disintegration of harmful networks. This paper presents an optimized attack strategy model for complex networks and introduces the tabu search into the network disintegration problem to identify the optimal attack strategy, which is a heuristic optimization algorithm and rarely applied to the study of network robustness. The efficiency of the proposed solution was verified by comparing it with other attack strategies used in various model networks and real-world network. Numerical experiments suggest that our solution can improve the effect of network disintegration and that the "best" choice for node failure attacks can be identified through global searches. Our understanding of the optimal attack strategy may also shed light on a new property of the nodes within network disintegration and deserves additional study.

  11. Survey of Attacks on Mobile AdhocWireless Networks

    Directory of Open Access Journals (Sweden)

    Vikas Solomon Abel

    2011-02-01

    Full Text Available Security has always been a key issue with wireless networks since there are no physical boundaries. Experience has shown numerous vulnerabilities to a variety of attacks even when security measures are in place. In the combined Internet-MANET environment also security is an important issue keeping in view the Internet connectivity and attack on the MANET protocols.

  12. Biochemistry of how plants resist insect attack determined

    OpenAIRE

    Trulove, Susan

    2010-01-01

    Many plants, including crops, release volatiles in response to insect attack. The chemical compounds can be a defense or can be an aromatic call for help to attract enemies of the attacking insect. Researchers from Virginia Tech, Michigan State University, and Georg-August-University Göttingen have discovered how plants produce the defensive compounds.

  13. Survey of Attacks on Mobile AdhocWireless Networks

    OpenAIRE

    Vikas Solomon Abel

    2011-01-01

    Security has always been a key issue with wireless networks since there are no physical boundaries. Experience has shown numerous vulnerabilities to a variety of attacks even when security measures are in place. In the combined Internet-MANET environment also security is an important issue keeping in view the Internet connectivity and attack on the MANET protocols.

  14. The LOCAL attack: Cryptanalysis of the authenticated encryption scheme ALE

    DEFF Research Database (Denmark)

    Khovratovich, Dmitry; Rechberger, Christian

    2014-01-01

    state bytes to the adversary. Our approach allows for a time-data complexity tradeoff, with an extreme case of a forgery produced after 2119 attempts and based on a single authenticated message. Our attack is further turned into a state recovery and a universal forgery attack with a time complexity...

  15. Randomized, controlled trial of telcagepant over four migraine attacks

    DEFF Research Database (Denmark)

    Ho, Andrew P; Dahlöf, Carl Gh; Silberstein, Stephen D; Saper, Joel R; Ashina, Messoud; Kost, James T; Froman, Samar; Leibensperger, Heather; Lines, Christopher R; Ho, Tony W

    2010-01-01

    This study evaluated the calcitonin gene-related peptide (CGRP) receptor antagonist telcagepant (tablet formulation) for treatment of a migraine attack and across four attacks. Adults with migraine were randomized, double-blind, to telcagepant 140 mg, telcagepant 280 mg, or control treatment sequ...

  16. A Taxonomy of Attacks on the DNP3 Protocol

    Science.gov (United States)

    East, Samuel; Butts, Jonathan; Papa, Mauricio; Shenoi, Sujeet

    Distributed Network Protocol (DNP3) is the predominant SCADA protocol in the energy sector - more than 75% of North American electric utilities currently use DNP3 for industrial control applications. This paper presents a taxonomy of attacks on the protocol. The attacks are classified based on targets (control center, outstation devices and network/communication paths) and threat categories (interception, interruption, modification and fabrication). To facilitate risk analysis and mitigation strategies, the attacks are associated with the specific DNP3 protocol layers they exploit. Also, the operational impact of the attacks is categorized in terms of three key SCADA objectives: process confi- dentiality, process awareness and process control. The attack taxonomy clarifies the nature and scope of the threats to DNP3 systems, and can provide insights into the relative costs and benefits of implementing mitigation strategies.

  17. Robustness against attacks of dual polarization encryption using the Stokes–Mueller formalism

    International Nuclear Information System (INIS)

    The security of our recently proposed dual polarization encryption scheme of images is evaluated by numerical simulations. This consists of testing the resistance of the scheme against brute force, known-plaintext, chosen-plaintext and video sequence attacks. While some attacks are ineffective (brute force, video sequence) others are effective (known-plaintext, chosen-plaintext), but only under certain assumptions. An optimization of the setup, which is based on a regular rotation of polarization optics angles (polarizers, wave plates), is proposed associating the use of a high dynamic range for the key image, or the use of a phase-only spatial light modulator in the target and in the key image channel. The possibility of the attacker decrypting an unknown image is thus strongly reduced. The precision required for optical specifications is also evaluated, in order to ensure a good decryption for an authorized user. (paper)

  18. Metrics for Assessment of Smart Grid Data Integrity Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Annarita Giani; Miles McQueen; Russell Bent; Kameshwar Poolla; Mark Hinrichs

    2012-07-01

    There is an emerging consensus that the nation’s electricity grid is vulnerable to cyber attacks. This vulnerability arises from the increasing reliance on using remote measurements, transmitting them over legacy data networks to system operators who make critical decisions based on available data. Data integrity attacks are a class of cyber attacks that involve a compromise of information that is processed by the grid operator. This information can include meter readings of injected power at remote generators, power flows on transmission lines, and relay states. These data integrity attacks have consequences only when the system operator responds to compromised data by redispatching generation under normal or contingency protocols. These consequences include (a) financial losses from sub-optimal economic dispatch to service loads, (b) robustness/resiliency losses from placing the grid at operating points that are at greater risk from contingencies, and (c) systemic losses resulting from cascading failures induced by poor operational choices. This paper is focused on understanding the connections between grid operational procedures and cyber attacks. We first offer two examples to illustrate how data integrity attacks can cause economic and physical damage by misleading operators into taking inappropriate decisions. We then focus on unobservable data integrity attacks involving power meter data. These are coordinated attacks where the compromised data are consistent with the physics of power flow, and are therefore passed by any bad data detection algorithm. We develop metrics to assess the economic impact of these attacks under re-dispatch decisions using optimal power flow methods. These metrics can be use to prioritize the adoption of appropriate countermeasures including PMU placement, encryption, hardware upgrades, and advance attack detection algorithms.

  19. Disorders of the cerebellopontine angle

    International Nuclear Information System (INIS)

    Disorders of the cerebellopontine angle may present by symptoms like vertigo, hearing problems, affection of the trigeminal or facial nerve. Ipsilateral ataxia and contralateral hemiparesis develop in case of a rather large tumor in this region and display an involvement of the cerebellum and/or brainstem. However, some of these typical symptoms are not recognized by the patient. Thus, in case of a suspicion of a disorder of the cerebellopontine angle the relevant functions have to be tested clinically. In addition, electrophysiology can confirm dysfunction of these cranial nerves. Mainstay of the therapy should be the treatment of the underlying cause. Nevertheless, not seldom it is necessary to treat symptoms like vertigo or facial pain. (orig.)

  20. Cross-correlation Based Synchronization Mechanism of LDDoS Attacks

    Directory of Open Access Journals (Sweden)

    Zhijun WU

    2014-03-01

    Full Text Available A success Low-rate Distributed Denial of Service (LDDoS attack is composed of many single sources of Low-rate Denial of Service (LDoS attacks, which are well-organized in time synchronization to aggregate the attack flow at the end of target router. This paper addresses time synchronization and flow aggregation in LDDoS attacks for the purpose of exploring the attack performance. A cross-correlation algorithm is proposed to guarantee all network-wide distributed attack pulses aggregate at the victim end with a strict time limitation to form a powerful attack pulse. Experiments on the attack performance of LDoS and LDDoS attack are performed in NS-2 simulation platform. Experiment results show that the LDDoS attack effects can be improved significantly by using cross-correlation algorithm to coordinate attack pulses, which obtain better attack performance than many single dependent attack pulses. 

  1. Analysis of Possible Attack on AODV Protocol in MANET

    Directory of Open Access Journals (Sweden)

    Nitesh Funde

    2014-05-01

    Full Text Available Mobile Ad Hoc Networks (MANETs consist of wireless mobile nodes which coordinate with each other to form temporary network without its pre-existing infrastructure. AODV is popular Ad-hoc distance vector routing reactive protocol which is used to find correct & shortest route to destination. Due to openness, dynamic, infrastructure-less nature, MANET are vulnerable to various attacks. One of these possible attacks is a Black Hole Attack in which a mobile node falsely replies to the source node that it is having a shortest path to the destination without checking its routing table. Therefore source node send all of its data to the black hole node and it deprives all the traffic of the source node. In this paper, We are proposing a technique to detect and prevent the multiple black hole nodes from MANET so that source to destination communication can be made easily. We also analysed the performance of the network in terms of number of packets sent, received, throughput, energy of network before attack and after detection & prevention of Attack. From these analysis, we can conclude that performance decreased due to attack can be improved after detection & prevention black hole attack in MANET.

  2. Visual Simulation of Missile Attacking Battleplane Based on Vega

    Directory of Open Access Journals (Sweden)

    Zhang Huibing

    2013-07-01

    Full Text Available A visual simulation system of fragment warhead missile attacking F-16C ''Falcon'' battleplane based on simulation and virtual reality technology is put forward. Firstly, the overall design of visual simulation of missile attacking F16 battleplane is implemented, and all functions of each module are demonstrated in detailed. Then 3D models in virtual battle field are optimized by level of detail, texture mapping, billboard and instance technology. Finally, Vega scene driving program is developed, and the implementation of special effect, view transform, preview and collision detect are emphasized. The result of simulation provides reference for damage assessment of missile attacking F16 battleplane.

  3. AMC Model for Denial of Sleep Attack Detection

    CERN Document Server

    Bhattasali, Tapalina

    2012-01-01

    Due to deployment in hostile environment, wireless sensor network is vulnerable to various attacks. Exhausted sensor nodes in sensor network become a challenging issue because it disrupts the normal connectivity of the network. Affected nodes give rise to denial of service that resists to get the objective of sensor network in real life. A mathematical model based on Absorbing Markov Chain (AMC)is proposed for Denial of Sleep attack detection in sensor network. In this mechanism, whether sensor network is affected by denial of sleep attack or not can be decided by considering expected death time of sensor network under normal scenario.

  4. Towards A Taxonomy Of Attacks Against Energy Control Systems

    Science.gov (United States)

    Fleury, Terry; Khurana, Himanshu; Welch, Von

    Control systems in the energy sector (e.g., supervisory control and data acquisition (SCADA) systems) involve a hierarchy of sensing, monitoring and control devices connected to centralized control stations or centers. The incorporation of commercial off-the-shelf technologies in energy control systems makes them vulnerable to cyber attacks. A taxonomy of cyber attacks against control systems can assist the energy sector in managing the cyber threat. This paper takes the first step towards a taxonomy by presenting a comprehensive model of attacks, vulnerabilities and damage related to control systems. The model is populated based on a survey of the technical literature from industry, academia and national laboratories.

  5. Blind Recognition of Touched Keys: Attack and Countermeasures

    OpenAIRE

    Yue, Qinggang; Ling, Zhen; Liu, Benyuan; Fu, Xinwen; Zhao, Wei

    2014-01-01

    In this paper, we introduce a novel computer vision based attack that discloses inputs on a touch enabled device, while the attacker cannot see any text or popups from a video of the victim tapping on the touch screen. In the attack, we use the optical flow algorithm to identify touching frames where the finger touches the screen surface. We innovatively use intersections of detected edges of the touch screen to derive the homography matrix mapping the touch screen surface in video frames to ...

  6. Effectiveness of the Call in Beach Volleyball Attacking Play

    OpenAIRE

    Künzell Stefan; Schweikart Florian; Köhn Daniel; Schläppi-Lienhard Olivia

    2014-01-01

    In beach volleyball the setter has the opportunity to give her or his hitter a “call”. The call intends that the setter suggests to her or his partner where to place the attack in the opponent’s court. The effectiveness of a call is still unknown. We investigated the women’s and men’s Swiss National Beach Volleyball Championships in 2011 and analyzed 2185 attacks. We found large differences between female and male players. While men called in only 38.4% of attacks, women used calls in 85.5% o...

  7. Compounding the Losses of Convoyed Ships Attacked by Tactical Submarines

    OpenAIRE

    Kåre M. Mjelde

    1982-01-01

    It is demonstrated that a time dependent stochastic model for the losses of convoyed ships attacked by submarines can be applied in the determination of the losses in terms of the results of two submodels:

  8. Compounding the Losses of Convoyed Ships Attacked by Tactical Submarines

    Directory of Open Access Journals (Sweden)

    Kåre M. Mjelde

    1982-10-01

    Full Text Available It is demonstrated that a time dependent stochastic model for the losses of convoyed ships attacked by submarines can be applied in the determination of the losses in terms of the results of two submodels:

  9. Analysis of the Fault Attack ECDLP over Prime Field

    Directory of Open Access Journals (Sweden)

    Mingqiang Wang

    2011-01-01

    Full Text Available In 2000, Biehl et al. proposed a fault-based attack on elliptic curve cryptography. In this paper, we refined the fault attack method. An elliptic curve E is defined over prime field p with base point P∈E(p. Applying the fault attack on these curves, the discrete logarithm on the curve can be computed in subexponential time of Lp(1/2,1+o(1. The runtime bound relies on heuristics conjecture about smooth numbers similar to the ones used by Lenstra, 1987.

  10. Enhancement of scale-free network attack tolerance

    Institute of Scientific and Technical Information of China (English)

    Qu Ze-Hui; Wang Pu; Song Chao-Ming; Qin Zhi-Guang

    2010-01-01

    Despite the large size of most communication and transportation systems, there are short paths between nodes in these networks which guarantee the efficient information, data and passenger delivery; furthermore these networks have a surprising tolerance under random errors thanks to their inherent scale-free topology. However, their scale-free topology also makes them fragile under intentional attacks, leaving us a challenge on how to improve the network robustness against intentional attacks without losing their strong tolerance under random errors and high message and passenger delivering capacity. Here we propose two methods (SL method and SH method) to enhance scale-free network's tolerance under attack in different conditions.

  11. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion of at...... attack surfaces of the cloud computing scenario participants. © 2010 IEEE....

  12. Assessing the effects of honeypots on cyber-attackers

    OpenAIRE

    Lim, Sze Li Harry

    2006-01-01

    A honeypot is a non-production system, design to interact with cyber-attackers to collect intelligence on attack techniques and behaviors. While the security community is reaping fruits of this collection tool, the hacker community is increasingly aware of this technology. In response, they develop anti-honeypot technology to detect and avoid honeypots. Prior to the discovery of newer intelligence collection tools, we need to maintain the relevancy of honeypot. Since the development of a...

  13. Security solution against denial of service attacks in BESIP system

    Science.gov (United States)

    Rezac, Filip; Voznak, Miroslav; Safarik, Jakub; Partila, Pavol; Tomala, Karel

    2013-05-01

    This article deals about embedded SIP communication server with an easy integration into the computer network based on open source solutions and its effective defense against the most frequent attack in the present - Denial of Service. The article contains brief introduction into the Bright Embedded Solution for IP Telephony - BESIP and describes the most common types of DoS attacks, which are applied on SIP elements of the VoIP infrastructure including the results of defensive mechanism that has been designed.

  14. Heart Attack

    Science.gov (United States)

    ... a million people in the U.S. have a heart attack. About half of them die. Many people have permanent heart damage or die because they don't get ... It's important to know the symptoms of a heart attack and call 9-1-1 if someone ...

  15. Evaluation of Security Attacks on UMTS Authentication Mechanism

    Directory of Open Access Journals (Sweden)

    Mojtaba Ayoubi Mobarhan

    2012-08-01

    Full Text Available In this study security of internet access over the Third Generation (3G telecommunication systems is considered and Universal Mobile Telecommunications System (UMTS is selected as the most popular system among 3G systems. The study then focuses on network access security mechanism of UMTS, called Authentication and Key Agreement (AKA. In addition, twenty types of important attacks and threats in UMTS system are presented and classified based on three major security factors; authentication, confidentiality, and data integrity. The evaluations finally show that the authentication factor is more interesting than other factors for hackers. Then, we describe four attacks named; man-inthe-middle, denial of service, identity catching, and redirection as the most significant attacks against authentication mechanism. Furthermore, we provide some solutions and methods to improve AKA mechanism and prevent these attacks in UMTS system.

  16. Analysis and mitigation of new network attack types

    OpenAIRE

    Hribar, Klemen

    2014-01-01

    Network security is an area that needs to be constantly monitored. New forms of network attacks are being discovered and can be divided into several categories. New forms of computer vulnerability can be monitored in various ways. It is important to rapidly discover ways to eliminate vulnerabilities and prevent their abuse. In the thesis, we have set ourselves the aim to conduct a review of recent network attacks and seek measures to prevent them. For this purpose, we have produced a short ov...

  17. Cognitive-behavioral treatment of panic attacks in chronic schizophrenia

    OpenAIRE

    Arlow, PB; Moran, ME; Bermanzohn, PC; Stronger, R; Siris, SG

    1997-01-01

    Although panic attacks have been described as relatively common in schizophrenia, few studies have examined treatments for this problem. Because cognitive-behavioral therapy (CBT) has demonstrated efficacy for panic disorder without schizophrenia, the authors conducted an open clinical trial of CBT for the treatment of panic attacks in schizophrenic patients. Eight patients meeting DSM-III-R criteria for schizophrenia and panic disorder were given a 16-week clinical trial of...

  18. A Comparative Study of Power Consumption Models for CPA Attack

    OpenAIRE

    Hassen Mestiri; Noura Benhadjyoussef; Mohsen Machhout; Rached Tourki

    2013-01-01

    Power analysis attacks are types of side channel attacks that are based on analyzing the power consumption of the cryptographic devices. Correlation power analysis is a powerful and efficient cryptanalytic technique. It exploits the linear relation between the predicted power consumption and the real power consumption of cryptographic devices in order to recover the correct key. The predicted power consumption is determined by using the appropriate consumption model. Until now, only a few mod...

  19. Opening Angles of Collapsar Jets

    OpenAIRE

    Mizuta, Akira; Ioka, Kunihito

    2013-01-01

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by $\\theta_j \\sim 1/5 \\Gamma_{0}$, and infer the initial Lorentz factor of the jet at the central engine, $\\Gamma_0$, is a few for existing observations of $\\theta_j$. The jet keeps the Lorentz factor low inside the star by converging cylindricall...

  20. A comparative analysis of network robustness against different link attacks

    Science.gov (United States)

    Duan, Boping; Liu, Jing; Zhou, Mingxing; Ma, Liangliang

    2016-04-01

    Recently, the study of optimizing network robustness has attracted increasing attentions, and the constraint that every node's degree cannot be changed is considered. Although this constraint maintains the node degree distribution consistently in order to reserve the structure of networks, it makes the network structure be lack of flexibility since many network structure always transform in the modern society. Given this consideration, in this paper, we analyze the robustness of networks through setting a new constraint; that is, only the number of edges should be unchanged. Then, we use the link-robustness index (Rl) as the measure of the network robustness against either random failures or intentional attacks, and make a comparative analysis of network robustness against different types of link attacks. Moreover, we use four types of networks as initial networks, namely scale-free networks, random networks, regular networks, and small-world networks. The experimental results show that the values of robustness measures for the optimized networks starting from different initial networks are similar under different link attacks, but the network topologies may be different. That is to say, networks with different topologies may have similar robustness in terms of the robustness measures. We also find that the optimized networks obtained by one link attack may not robust against other link attacks, sometimes, even weaker than the original networks. Therefore, before building networks, it is better to study which type of link attacks may happen.

  1. Automatic Generation of Correlation Rules to Detect Complex Attack Scenarios

    OpenAIRE

    Godefroy, Erwan; Totel, Eric; Hurfin, Michel; Majorczyk, Frédéric

    2014-01-01

    In large distributed information systems, alert correlation systems are necessary to handle the huge amount of elementary security alerts and to identify complex multi-step attacks within the flow of low level events and alerts. In this paper, we show that, once a human expert has provided an action tree derived from an attack tree, a fully automated transformation process can generate exhaustive correlation rules that would be tedious and error prone to enumerate by hand. The transformation ...

  2. Analysis of Topology Poisoning Attacks in Software-Defined Networking

    OpenAIRE

    Thanh Bui, Tien

    2015-01-01

    Software-defined networking (SDN) is an emerging architecture with a great potential to foster the development of modern networks. By separating the control plane from the network devices and centralizing it at a software-based controller, SDN provides network-wide visibility and flexible programmability to network administrators. However, the security aspects of SDN are not yet fully understood. For example, while SDN is resistant to some topology poisoning attacks in which the attacker misl...

  3. Denial of service attacks and challenges in broadband wireless networks

    OpenAIRE

    Khan, S.; Loo, KK; Naeem, T; Khan, MA

    2008-01-01

    Broadband wireless networks are providing internet and related services to end users. The three most important broadband wireless technologies are IEEE 802.11, IEEE 802.16, and Wireless Mesh Network (WMN). Security attacks and vulnerabilities vary amongst these broadband wireless networks because of differences in topologies, network operations and physical setups. Amongst the various security risks, Denial of Service (DoS) attack is the most severe security threat, as DoS can compromis...

  4. Vulnerability of water supply systems to cyber-physical attacks

    Science.gov (United States)

    Galelli, Stefano; Taormina, Riccardo; Tippenhauer, Nils; Salomons, Elad; Ostfeld, Avi

    2016-04-01

    The adoption of smart meters, distributed sensor networks and industrial control systems has largely improved the level of service provided by modern water supply systems. Yet, the progressive computerization exposes these critical infrastructures to cyber-physical attacks, which are generally aimed at stealing critical information (cyber-espionage) or causing service disruption (denial-of-service). Recent statistics show that water and power utilities are undergoing frequent attacks - such as the December power outage in Ukraine - , attracting the interest of operators and security agencies. Taking the security of Water Distribution Networks (WDNs) as domain of study, our work seeks to characterize the vulnerability of WDNs to cyber-physical attacks, so as to conceive adequate defense mechanisms. We extend the functionality of EPANET, which models hydraulic and water quality processes in pressurized pipe networks, to include a cyber layer vulnerable to repeated attacks. Simulation results on a medium-scale network show that several hydraulic actuators (valves and pumps, for example) can be easily attacked, causing both service disruption - i.e., water spillage and loss of pressure - and structural damages - e.g., pipes burst. Our work highlights the need for adequate countermeasures, such as attacks detection and reactive control systems.

  5. Impact modeling and prediction of attacks on cyber targets

    Science.gov (United States)

    Khalili, Aram; Michalk, Brian; Alford, Lee; Henney, Chris; Gilbert, Logan

    2010-04-01

    In most organizations, IT (information technology) infrastructure exists to support the organization's mission. The threat of cyber attacks poses risks to this mission. Current network security research focuses on the threat of cyber attacks to the organization's IT infrastructure; however, the risks to the overall mission are rarely analyzed or formalized. This connection of IT infrastructure to the organization's mission is often neglected or carried out ad-hoc. Our work bridges this gap and introduces analyses and formalisms to help organizations understand the mission risks they face from cyber attacks. Modeling an organization's mission vulnerability to cyber attacks requires a description of the IT infrastructure (network model), the organization mission (business model), and how the mission relies on IT resources (correlation model). With this information, proper analysis can show which cyber resources are of tactical importance in a cyber attack, i.e., controlling them enables a large range of cyber attacks. Such analysis also reveals which IT resources contribute most to the organization's mission, i.e., lack of control over them gravely affects the mission. These results can then be used to formulate IT security strategies and explore their trade-offs, which leads to better incident response. This paper presents our methodology for encoding IT infrastructure, organization mission and correlations, our analysis framework, as well as initial experimental results and conclusions.

  6. Asessing ethical severity of e-learning systems security attacks

    OpenAIRE

    LEVY, Y.; Ramim, MM; Hackney, RA

    2013-01-01

    Security and ethical issues with information systems (IS) are important concerns for most organizations. However, limited attention has been given to unethical behaviors and severity of cyber-security attacks, while these instances appear to be critically important. Although managers have been embracing e-learning systems for training and virtual-team collaborations, little is known about motivations for cyber-security attacks on such systems

  7. Impact of Degree Heterogeneity on Attack Vulnerability of Interdependent Networks.

    Science.gov (United States)

    Sun, Shiwen; Wu, Yafang; Ma, Yilin; Wang, Li; Gao, Zhongke; Xia, Chengyi

    2016-01-01

    The study of interdependent networks has become a new research focus in recent years. We focus on one fundamental property of interdependent networks: vulnerability. Previous studies mainly focused on the impact of topological properties upon interdependent networks under random attacks, the effect of degree heterogeneity on structural vulnerability of interdependent networks under intentional attacks, however, is still unexplored. In order to deeply understand the role of degree distribution and in particular degree heterogeneity, we construct an interdependent system model which consists of two networks whose extent of degree heterogeneity can be controlled simultaneously by a tuning parameter. Meanwhile, a new quantity, which can better measure the performance of interdependent networks after attack, is proposed. Numerical simulation results demonstrate that degree heterogeneity can significantly increase the vulnerability of both single and interdependent networks. Moreover, it is found that interdependent links between two networks make the entire system much more fragile to attacks. Enhancing coupling strength between networks can greatly increase the fragility of both networks against targeted attacks, which is most evident under the case of max-max assortative coupling. Current results can help to deepen the understanding of structural complexity of complex real-world systems. PMID:27609483

  8. Robustness of network of networks under targeted attack

    Science.gov (United States)

    Dong, Gaogao; Gao, Jianxi; Du, Ruijin; Tian, Lixin; Stanley, H. Eugene; Havlin, Shlomo

    2013-05-01

    The robustness of a network of networks (NON) under random attack has been studied recently [Gao , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.195701 107, 195701 (2011)]. Understanding how robust a NON is to targeted attacks is a major challenge when designing resilient infrastructures. We address here the question how the robustness of a NON is affected by targeted attack on high- or low-degree nodes. We introduce a targeted attack probability function that is dependent upon node degree and study the robustness of two types of NON under targeted attack: (i) a tree of n fully interdependent Erdős-Rényi or scale-free networks and (ii) a starlike network of n partially interdependent Erdős-Rényi networks. For any tree of n fully interdependent Erdős-Rényi networks and scale-free networks under targeted attack, we find that the network becomes significantly more vulnerable when nodes of higher degree have higher probability to fail. When the probability that a node will fail is proportional to its degree, for a NON composed of Erdős-Rényi networks we find analytical solutions for the mutual giant component P∞ as a function of p, where 1-p is the initial fraction of failed nodes in each network. We also find analytical solutions for the critical fraction pc, which causes the fragmentation of the n interdependent networks, and for the minimum average degree k¯min below which the NON will collapse even if only a single node fails. For a starlike NON of n partially interdependent Erdős-Rényi networks under targeted attack, we find the critical coupling strength qc for different n. When q>qc, the attacked system undergoes an abrupt first order type transition. When q≤qc, the system displays a smooth second order percolation transition. We also evaluate how the central network becomes more vulnerable as the number of networks with the same coupling strength q increases. The limit of q=0 represents no dependency, and the results are consistent with

  9. Factors governing risk of cougar attacks on humans

    Science.gov (United States)

    Mattson, David; Logan, Kenneth; Sweanor, Linda

    2011-01-01

    Since the 1980s wildlife managers in the United States and Canada have expressed increasing concern about the physical threat posed by cougars (Puma concolor) to humans. We developed a conceptual framework and analyzed 386 human–cougar encounters (29 fatal attacks, 171 instances of nonfatal contact, and 186 close-threatening encounters) to provide information relevant to public safety. We conceived of human injury and death as the outcome of 4 transitions affected by different suites of factors: (1) a human encountering a cougar: (2) given an encounter, odds that the cougar would be aggressive; (3) given aggression, odds that the cougar would attack; and (4) given an attack, odds that the human would die. We developed multivariable logistic regression models to explain variation in odds at transitions three and four using variables pertaining to characteristics of involved people and cougars. Young (≤ 2.5 years) or unhealthy (by weight, condition, or disease) cougars were more likely than any others to be involved in close (typically <5 m) encounters that threatened the involved person. Of cougars in close encounters, females were more likely than males to attack, and of attacking animals, adults were more likely than juveniles to kill the victim (32% versus 9% fatality, respectively). During close encounters, victims who used a weapon killed the involved cougar in 82% of cases. Other mitigating behaviors (e.g., yelling, backing away, throwing objects, increasing stature) also substantially lessened odds of attack. People who were moving quickly or erratically when an encounter happened (running, playing, skiing, snowshoeing, biking, ATV-riding) were more likely to be attacked and killed compared to people who were less active (25% versus 8% fatality). Children (≤ 10 years) were more likely than single adults to be attacked, but intervention by people of any age reduced odds of a child’s death by 4.6×. Overall, cougar attacks on people in Canada and the

  10. A Strategic Analysis of Information Sharing Among Cyber Attackers

    Directory of Open Access Journals (Sweden)

    Kjell Hausken

    2015-10-01

    Full Text Available We build a game theory model where the market design is such that one firm invests in security to defend against cyber attacks by two hackers. The firm has an asset, which is allocated between the three market participants dependent on their contest success. Each hacker chooses an optimal attack, and they share information with each other about the firm’s vulnerabilities. Each hacker prefers to receive information, but delivering information gives competitive advantage to the other hacker. We find that each hacker’s attack and information sharing are strategic complements while one hacker’s attack and the other hacker’s information sharing are strategic substitutes. As the firm’s unit defense cost increases, the attack is inverse U-shaped and reaches zero, while the firm’s defense and profit decrease, and the hackers’ information sharing and profit increase. The firm’s profit increases in the hackers’ unit cost of attack, while the hackers’ information sharing and profit decrease. Our analysis also reveals the interesting result that the cumulative attack level of the hackers is not affected by the effectiveness of information sharing between them and moreover, is also unaffected by the intensity of joint information sharing. We also find that as the effectiveness of information sharing between hackers increases relative to the investment in attack, the firm’s investment in cyber security defense and profit are constant, the hackers’ investments in attacks decrease, and information sharing levels and hacker profits increase. In contrast, as the intensity of joint information sharing increases, while the firm’s investment in cyber security defense and profit remain constant, the hackers’ investments in attacks increase, and the hackers’ information sharing levels and profits decrease. Increasing the firm’s asset causes all the variables to increase linearly, except information sharing which is constant. We extend

  11. The qualitative criterion of transient angle stability

    OpenAIRE

    Lyu, R; Xue, Y.; Xue, F; Wu, Qiuwei; Yang, Guangya; Zhou, H; Ju, P.

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust of these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the crit...

  12. The radiographic diagnosis of early attacking congenital syphilis of bone

    International Nuclear Information System (INIS)

    Objective: To explore the method of radiological diagnosis of early attacking congenital syphilis. Methods: Seven cases of early attacking congenital syphilis of bone were retrospectively analyzed, diagnosed serologically, and were taken X-rays of the long bones. Results: Bone radiographs abnormalities were identified in 6 of 7 cases. Five cases suffered periotities, six cases metaphysitis, and three cases combined with diaphysitis. Seven cases had swollen soft tissue. The vertebraes, craniums and epiphysitis were not found abnormal in 7 cases. Diffusion, multiple and symmetric metaphysitis, periosteitis and osteitis were the radiological characters of congenital syphilis of bone. Conclusion: Radiography can affirm the diagnose of early attacking congenital syphilis and definite the arrange and depth. Radiographs of the extremities should be routinely taken in suspected infants. (authors)

  13. Generating IDS Attack Pattern Automatically Based on Attack Tree

    Institute of Scientific and Technical Information of China (English)

    向尕; 曹元大

    2003-01-01

    Generating attack pattern automatically based on attack tree is studied. The extending definition of attack tree is proposed. And the algorithm of generating attack tree is presented. The method of generating attack pattern automatically based on attack tree is shown, which is tested by concrete attack instances. The results show that the algorithm is effective and efficient. In doing so, the efficiency of generating attack pattern is improved and the attack trees can be reused.

  14. Value of ABCD2-F in Predicting Cerebral Ischemic Attacks: Three Months Follow-Up after the Primary Attack.

    Science.gov (United States)

    Chardoli, Mojtaba; Firoozabadi, Nader H; Nouri, Mohsen; Rahimi-Movaghar, Vafa

    2016-06-01

    Cerebrovascular attack (CVA) and transient ischemic attack (TIA) are major causes of emergency department visits around the globe. A significant number of these patients may experience repeat attacks if left untreated. Several risk stratifying scoring systems have been developed in recent years to point out the high risk patients. ABCD2 is based on age, blood pressure, clinical status, diabetes mellitus, and duration of symptoms and is used commonly for this purpose. In this study, we were to enhance its sensitivity and specificity with the addition of another criterion namely atrial fibrillation and making ABCD2-F. A prospective study in two hospitals was performed and 138 patients diagnosed with TIA/CVA were enrolled. Demographic, clinical, and paraclinical data of all patients were registered. All patients were followed for three months for any sign or symptom of a recurrent ischemic attack. Recurrent ischemic attacks happened in 9.4% of the patients. None of the criteria of ABCD2-F was associated with higher chance of ischemic attacks. Similarly, ABCD2-F was not different between patients with or without repeat cerebral ischemia. The addition of atrial fibrillation to ABCD2 did not enhance the accuracy of this scoring system to detect patients high risk for repeat cerebral ischemia. More studies in the future to improve sensitivity and specificity of this test are warranted. PMID:27306346

  15. Formalized Description of Distributed Denial of Service Attack

    Institute of Scientific and Technical Information of China (English)

    杜彦辉; 马锐; 刘玉树

    2004-01-01

    The distributed denial of service (DDoS) attack is one of the dangers in intrusion modes. It's difficult to defense and can cause serious damage to the system. Based on a careful study of the attack principles and characteristics, an object-oriented formalized description is presented, which contains a three-level framework and offers full specifications of all kinds of DDoS modes and their features and the relations between one another. Its greatest merit lies in that it contributes to analyzing, checking and judging DDoS. Now this formalized description has been used in a special IDS and it works very effectively.

  16. PREVENTION OF ATTACKS BASED ON DOS AND ITS DETECTION

    Directory of Open Access Journals (Sweden)

    N.Vijaya Sunder Sagar

    2013-08-01

    Full Text Available Here a mechanism has been explored against the attacks of DDOS. In the present generation this problem is creating a lot of trouble to internet. Therefore a new method is proposed for the attacks of the DDOS in the case of spoofing of IP and their flow of attack. Which is creating a major threat towards the internet, the proposed method includes an implementation of the firewall which separates threat data and the legitimate user data respectively, then after the separation of the affected data before it reach the final destination address. The present scheme is very efficient in terms of the cost. The present process requires only twenty percent of co operation from the routers of the internet in the process of marking. In the present methodology therefore for the fast and accurate detection of the attacks a new system is designed which is based on its own configuration. A huge evaluation takes place on the present methodology by implementation on the several attacks. By the analysis of the experiments reveals that more than ninety percents of the threats can be resolved without troubling the present scenario.

  17. A Comparison of Link Layer Attacks on Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Shahriar Mohammadi

    2011-03-01

    Full Text Available Wireless sensor networks (WSNs have many potential applications [1, 5] and unique challenges. Theyusually consist of hundreds or thousands small sensor nodes such as MICA2, which operateautonomously; conditions such as cost, invisible deployment and many application domains, lead to smallsize and limited resources sensors [2]. WSNs are susceptible to many types of link layer attacks [1] andmost of traditional networks security techniques are unusable on WSNs [2]; due to wireless and sharednature of communication channel, untrusted transmissions, deployment in open environments, unattendednature and limited resources [1]. So, security is a vital requirement for these networks; but we have todesign a proper security mechanism that attends to WSN's constraints and requirements. In this paper, wefocus on security of WSNs, divide it (the WSNs security into four categories and will consider them,include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs' linklayer attacks and a comparison of them. This work enables us to identify the purpose and capabilities ofthe attackers; also, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paperdiscusses known approaches of security detection and defensive mechanisms against the link layerattacks; this would enable it security managers to manage the link layer attacks of WSNs more effectively

  18. Risk of Wheezing Attacks in Infants With Transient Tachypnea Newborns

    Science.gov (United States)

    Golshantafti, Mohammad; Yavari, Tahereh; Afrand, Mohammadhosain

    2016-01-01

    Background: The most common reason of respiratory distress in the newborn is transient tachypnea of the newborn (TTN). There are some reports saying that TTN is associated with increased frequencies of wheezing attacks. Objectives: The aims of this study were to determine the risk factors associated with TTN and to determine the association between TTN and the development of wheezing syndromes in early life. Materials and Methods: In a historical cohort study, we recorded the characteristics of 70 infants born at the Shohadaye Kargar Hospital in Yazd between March 2005 and March 2009 and who were hospitalized because of TTN in the neonatal intensive-care unit. We called their parents at least four years after the infants were discharged from the hospital and asked about any wheezing attacks. Seventy other infants with no health problems during the newborn period were included in the study as the control group. Results: The rate of wheezing attacks in newborns with TTN was more than patients with no TTN diagnosis (P = 0.014). TTN was found to be an independent risk factor for later wheezing attacks (relative risk [RR] = 2.8). Conclusions: The most obvious finding of this study was that TTN was an independent risk factor for wheezing attacks. So long-term medical care is suggested for these patients who may be at risk, because TTN may not be as transient as has been previously thought. PMID:26848370

  19. Performance Comparison of Routing Attacks in Manet and WSN

    Directory of Open Access Journals (Sweden)

    Shyamala Ramachandran

    2012-08-01

    Full Text Available Routing is a basic step for data exchange. In wirel ess ad-hoc networks each node acts as a router and executes a routing protocol. Wireless ad-hoc networ ks are highly resource constrained in terms of network topology, memory and computation power. The reliable data transfer is a difficult task in wireless ad-hoc networks because of resource constr aints. A mobile ad-hoc network (MANET is a kind of wireless ad-hoc network, and is a self-configuri ng network of mobile routers connected by wireless links. A wireless sensor network (WSN is a highly constrained wireless ad-hoc network. In these network, multicast is the efficient routing service for data broadcasting. Denial of service (DOS att ack, sinkhole, wormhole, sybil, black hole and rushing a ttacks are some routing attacks. So, it is necessar y to study the impact of routing attacks on existing mul ticast routing protocols to suggest a suitable secu re multicast routing protocol. The objective of this p aper is to study the effects of black hole and rush ing attack on MANET and WSN. The NS-2 based simulation is used in analyzing the black hole and rushing attacks. From performance metrics such as packet de livery ratio (PDR, packet drop ratio (PDrR, network throughput (NTh and energy consumption it is observed that the routing attacks have severe impact on MANET than WSN.

  20. Myocardial perfusion imaging study of CO(2)-induced panic attack.

    Science.gov (United States)

    Soares-Filho, Gastão L F; Machado, Sergio; Arias-Carrión, Oscar; Santulli, Gaetano; Mesquita, Claudio T; Cosci, Fiammetta; Silva, Adriana C; Nardi, Antonio E

    2014-01-15

    Chest pain is often seen alongside with panic attacks. Moreover, panic disorder has been suggested as a risk factor for cardiovascular disease and even a trigger for acute coronary syndrome. Patients with coronary artery disease may have myocardial ischemia in response to mental stress, in which panic attack is a strong component, by an increase in coronary vasomotor tone or sympathetic hyperactivity setting off an increase in myocardial oxygen consumption. Indeed, coronary artery spasm was presumed to be present in cases of cardiac ischemia linked to panic disorder. These findings correlating panic disorder with coronary artery disease lead us to raise questions about the favorable prognosis of chest pain in panic attack. To investigate whether myocardial ischemia is the genesis of chest pain in panic attacks, we developed a myocardial perfusion study through research by myocardial scintigraphy in patients with panic attacks induced in the laboratory by inhalation of 35% carbon dioxide. In conclusion, from the data obtained, some hypotheses are discussed from the viewpoint of endothelial dysfunction and microvascular disease present in mental stress response. PMID:24188891

  1. INTRA-SNAIL LIDOCAIN FOR TREATMENT OF MIGRAINE ATTACK

    Institute of Scientific and Technical Information of China (English)

    Qu Songbin; Wang Xiaofeng

    2000-01-01

    OBJECTIVE To explore a mcthod of trcating migraine attack. BACKROUND Migraine is the most common disorder which causcs .severe headache, nausea and vomiting in attack continuing several hours. There is little method to cease migraine attack quickly. METHOD The patients lied down and kept the head backward. Lidocain 2% 1 to 2 ml was slowly instilled into the nostril ipsilatcral to thc headache. RESULTS Pain relief was achievcd in minutes. The headache disappeared in 19 cases and slight headache rcmained in 2 cases mong 21 cascs. TCD (transcranial dopple ) was tested in 6 cases before thc treatment and 5 minutes after thc treatment. The results showed that CBF (cerebral blood flow) velocity diminished before thc treatment and increased to normal value after the treatment in 5 cases, and it increased beforc thc treatment in another case and diminished after the treatment. DISSCUSION Thc migraine attacks are associated with dysfunction of the vascular constriction and vasodilatation. It was reported that Lidocain had diplex effect that induce the vascular constriction and also induce vasodilatation on the bases of regulation of the autonomic nerves. Medications to abort the attack dramatically by the transnasal route.. CONCLUSION This method is casy to use, painless and effective.

  2. Detection of Attacks on MAODV Association Rule Mining Optimization

    Directory of Open Access Journals (Sweden)

    A. Fidalcastro

    2015-02-01

    Full Text Available Current mining algorithms can generate large number of rules and very slow to generate rules or generate few results, omitting interesting and valuable information. To address this problem, we propose an algorithm Optimized Featured Top Association Rules (OFTAR algorithm, where every attack have many features and some of the features are more important. The Features are selected by genetic algorithm and processed by the OFTAR algorithm to find the optimized rules. The algorithm utilizes Genetic Algorithm feature selection approach to find optimized features. OFTAR incorporate association rules with several rule optimization techniques and expansion techniques to improve efficiency. Increasing popularity of Mobile ad hoc network users of wireless networks lead to threats and attacks on MANET, due to its features. The main challenge in designing a MANET is protecting from various attacks in the network. Intrusion Detection System is required to monitor the network and to detect the malicious node in the network in multi casting mobility environment. The node features are processed in Association Analysis to generate rules, the generated rules are applied to nodes to detect the attacks. Experimental results show that the algorithm has higher scalability and good performance that is an advantageous to several association rule mining algorithms when the rule generation is controlled and optimized to detect the attacks.

  3. Heart Attack Recovery FAQs

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More Heart Attack Recovery FAQs Updated:Aug 24,2016 Most people ... recovery. View an animation of a heart attack . Heart Attack Recovery Questions and Answers What treatments will I ...

  4. Computing Preferred Extensions for Argumentation Systems with Sets of Attacking

    DEFF Research Database (Denmark)

    Nielsen, Søren Holbech; Parsons, Simon

    2006-01-01

    The hitherto most abstract, and hence general, argumentation system, is the one described by Dung in a paper from 1995. This framework does not allow for joint attacks on arguments, but in a recent paper we adapted it to support such attacks, and proved that this adapted framework enjoyed the sam...... these systems. In this paper we propose a method for enumerating preferred extensions of the potentially more complex systems, where joint attacks are allowed. The method is inspired by the one given by Doutre and Mengin.......The hitherto most abstract, and hence general, argumentation system, is the one described by Dung in a paper from 1995. This framework does not allow for joint attacks on arguments, but in a recent paper we adapted it to support such attacks, and proved that this adapted framework enjoyed the same...... formal properties as that of Dung. One problem posed by Dung's original framework, which was neglected for some time, is how to compute preferred extensions of the argumentation systems. However, in 2001, in a paper by Doutre and Mengin, a procedure was given for enumerating preferred extensions for...

  5. Distributed Denial of Service (DDoS) Attacks Detection Mechanism

    CERN Document Server

    Kumarasamy, Saravanan

    2012-01-01

    Pushback is a mechanism for defending against Distributed Denial-of-Service (DDoS) attacks. DDoS attacks are treated as a congestion-control problem, but because most such congestion is caused by malicious hosts not obeying traditional end-to-end congestion control, the problem must be handled by the routers. Functionality is added to each router to detect and preferentially drop packets that probably belong to an attack. Upstream routers are also notified to drop such packets in order that the router's resources be used to route legitimate traffic hence term pushback. Client puzzles have been advocated as a promising countermeasure to DoS attacks in the recent years. In order to identify the attackers, the victim server issues a puzzle to the client that sent the traffic. When the client is able to solve the puzzle, it is assumed to be authentic and the traffic from it is allowed into the server. If the victim suspects that the puzzles are solved by most of the clients, it increases the complexity of the puz...

  6. Why do chimpanzee males attack the females of neighboring communities?

    Science.gov (United States)

    Pradhan, Gauri R; Pandit, Sagar A; Van schaik, Carel P

    2014-11-01

    Our closest nonhuman primate relatives, chimpanzees, engage in potentially lethal between-group conflict; this collective aggressive behavior shows parallels with human warfare. In some communities, chimpanzee males also severely attack and even kill females of the neighboring groups. This is surprising given their system of resource defense polygyny, where males are expected to acquire potential mates. We develop a simple mathematical model based on reproductive skew among primate males to solve this puzzle. The model predicts that it is advantageous for high-ranking males but not for low-ranking males to attack females. It also predicts that more males gain a benefit from attacking females as the community's reproductive skew decreases, i.e., as mating success is more evenly distributed. Thus, fatal attacks on females should be concentrated in communities with low reproductive skew. These attacks should also concur with between-community infanticide. A review of the chimpanzee literature provides enough preliminary support for this prediction to warrant more detailed testing. PMID:25100507

  7. Panic Attack

    OpenAIRE

    Scantamburlo, Gabrielle; Ansseau, Marc

    2004-01-01

    Panic attacks can occur unexpectedly and in almost any situation. The present article discusses the main features of anxiety states, the approach, the management and the practice guidelines for the treatment of panic disorder. Peer reviewed

  8. Hydrogen attack evaluation of boiler tube using ultrasonic wave

    International Nuclear Information System (INIS)

    The presence of hydrogen in industrial plants is a source of damage. Hydrogen attack is one such form of degradation and often causing large tube ruptures that necessitate an immediate shutdown. Hydrogen attack may reduce the fracture toughness as well as the strength of steels. This reduction is caused partially by the presence of cavities and microcracks at the grain boundaries. In the past several techniques have been used with limited results. This paper describes the application of an ultrasonic velocity, attenuation and backscatter techniques for detecting the presence of hydrogen damage in utility boiler tubes. Ultrasonic tests showed a decrease in wave velocity and an increase in attenuation. Such results demonstrate the potential for ultrasonic nondestructive testing to quantify damage. Based on this study, recommendations are that both velocity and attenuation be used to detect hydrogen attack in steels.

  9. PREVENTION OF WORMHOLE ATTACK IN WIRELESS SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    Dhara Buch

    2011-10-01

    Full Text Available Ubiquitous and pervasive applications, where the Wireless Sensor Networks are typically deployed, leadto the susceptibility to many kinds of security attacks. Sensors used for real time response capability alsomake it difficult to devise the resource intensive security protocols because of their limited battery, power,memory and processing capabilities. One of potent form of Denial of Service attacks is Wormhole attackthat affects on the network layer. In this paper, the techniques dealing with wormhole attack areinvestigated and an approach for wormhole prevention is proposed. Our approach is based on theanalysis of the two-hop neighbors forwarding Route Reply packet. To check the validity of the sender, aunique key between the individual sensor node and the base station is required to be generated bysuitable scheme.

  10. Identification Method of Attack Path Based on Immune Intrusion Detection

    Directory of Open Access Journals (Sweden)

    Wenhua Huang

    2014-04-01

    Full Text Available This thesis takes researches on the immune intrusion detection and IP trace back technology. To find out the network data features of the real-time analyses, the distributed immune intrusion detection system and the packet marking theory are used; to guide the dynamically processing of path signs technology, the immune intrusion detection system is used; what’s more, to dynamically adaptive different methods of characteristics of network data, the path signs technology is adopted. After that, the attack paths can be quickly identified to provide path information for feature detector on attack path in the immune intrusion detection system. Experiment results show that this scheme can quickly reconstruct the attack path information, and the performance on the aspects of the convergence is with efficiency rate and false positive rate, which is superior to the current probabilistic packet marking algorithm and can provide characteristic path information for immune intrusion detection system

  11. Identifying optimal targets of network attack by belief propagation

    CERN Document Server

    Mugisha, Salomon

    2016-01-01

    For a network formed by nodes and undirected links between pairs of nodes, the network optimal attack problem aims at deleting a minimum number of target nodes to break the network down into many small components. This problem is intrinsically related to the feedback vertex set problem that was successfully tackled by spin glass theory and an associated belief propagation-guided decimation (BPD) algorithm [H.-J. Zhou, Eur.~Phys.~J.~B 86 (2013), 455]. In the present work we apply a slightly adjusted version of the BPD algorithm to the network optimal attack problem, and demonstrate that it has much better performance than a recently proposed Collective Information algorithm [F. Morone and H. A. Makse, Nature 524 (2015), 63--68] for different types of random networks and real-world network instances. The BPD-guided attack scheme often induces an abrupt collapse of the whole network, which may make it very difficult to defend.

  12. Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure

    Directory of Open Access Journals (Sweden)

    Harsha L Rao

    2012-01-01

    Full Text Available Background: Blotchy pigments in the anterior chamber (AC angle are considered diagnostic of primary angle closure (PAC. But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects, above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3 and in open angles was 4.7% (95% CI, 3.2-6.3. Blotchy pigments were more frequently seen in inferior (16% and superior quadrants (15% of occludable angles, and inferior quadrant of open angles (4%. Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1. Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments.

  13. Heart Attack

    Science.gov (United States)

    ... having another heart attack. These medicines include: aspirin, beta blockers, statins, ACE inhibitors and fish oil. Your doctor ... have had a stent placed in your heart. Beta blockers are a group of drugs that lower the ...

  14. A Model of Biological Attacks on a Realistic Population

    Science.gov (United States)

    Carley, Kathleen M.; Fridsma, Douglas; Casman, Elizabeth; Altman, Neal; Chen, Li-Chiou; Kaminsky, Boris; Nave, Demian; Yahja, Alex

    The capability to assess the impacts of large-scale biological attacks and the efficacy of containment policies is critical and requires knowledge-intensive reasoning about social response and disease transmission within a complex social system. There is a close linkage among social networks, transportation networks, disease spread, and early detection. Spatial dimensions related to public gathering places such as hospitals, nursing homes, and restaurants, can play a major role in epidemics [Klovdahl et. al. 2001]. Like natural epidemics, bioterrorist attacks unfold within spatially defined, complex social systems, and the societal and networked response can have profound effects on their outcome. This paper focuses on bioterrorist attacks, but the model has been applied to emergent and familiar diseases as well.

  15. A Review of Techniques to Mitigate Sybil Attacks

    Directory of Open Access Journals (Sweden)

    Nitish Balachandran

    2012-07-01

    Full Text Available Any decentralised distributed network is particularly vulnerable to the Sybil attack wherein a malicious node masquerades as several different nodes, called Sybil nodes, simultaneously in an attempt to disrupt the proper functioning of the network. Such attacks may cause damage on a fairly large scale especially since they are difficult to detect and there has been no universally accepted scheme to counter them as yet. In this paper, we discuss the different kinds of Sybil attacks including those occurring in peer-to-peer reputation systems, selforganising networks and even social network systems. In addition, various methods that have been suggested over time to decrease or eliminate their risk completely are also analysed along with their modus operandi.

  16. An ensemble approach for feature selection of Cyber Attack Dataset

    CERN Document Server

    Singh, Shailendra

    2009-01-01

    Feature selection is an indispensable preprocessing step when mining huge datasets that can significantly improve the overall system performance. Therefore in this paper we focus on a hybrid approach of feature selection. This method falls into two phases. The filter phase select the features with highest information gain and guides the initialization of search process for wrapper phase whose output the final feature subset. The final feature subsets are passed through the Knearest neighbor classifier for classification of attacks. The effectiveness of this algorithm is demonstrated on DARPA KDDCUP99 cyber attack dataset.

  17. Treatment of HAE Attacks in the Icatibant Outcome Survey

    DEFF Research Database (Denmark)

    Hernández Fernandez de Rojas, Dolores; Ibañez, Ethel; Longhurst, Hilary; Maurer, Marcus; Fabien, Vincent; Aberer, Werner; Bouillet, Laurence; Zanichelli, Andrea; Caballero, Teresa; Bygum, Anette

    2015-01-01

    treated with self-administered and HCP-administered icatibant in a real-world setting. METHODS: The Icatibant Outcome Survey (Shire, Zug, Switzerland; NCT01034969) is an international observational study monitoring the safety and effectiveness of icatibant treatment. Descriptive retrospective analyses......-administration. CONCLUSIONS: The proportion of HAE attacks treated with self-administered icatibant increased over time. Patients successfully self-administered icatibant for a wide variety of HAE attacks, demonstrating that icatibant is generally well tolerated and effective for self-administration. Self-administration of...

  18. Matrix metalloproteinases during and outside of migraine attacks without aura

    DEFF Research Database (Denmark)

    Ashina, M.; Tvedskov, J.F.; Thiesen, Kerstin Lipka;

    2010-01-01

    Ashina M, Tvedskov JF, Lipka K, Bilello J, Penkowa M & Olesen J. Matrix metalloproteinases during and outside of migraine attacks without aura. Cephalalgia 2009. London. ISSN 0333-1024To test the hypothesis that permeability of the blood-brain barrier (BBB) is altered during migraine attack due to...... proteins including MMP-7, -8, -10 and TIMP-2. We used Rules-Based Medicine multi-analyte profiling and protein array technologies to study plasma concentration of MMPs. There was no difference in MMP-9 and TIMP-1 levels between ictal and interictal periods. We found significantly decreased plasma levels of...

  19. An Assessment of Worm Hole attack over Mobile Ad-Hoc Network as serious threats

    Directory of Open Access Journals (Sweden)

    Vikas Kumar Upadhyay

    2013-07-01

    Full Text Available Now these day Mobile Ad hoc networks vulnerable from number of security threats like black hole attack, DOS attack, Byzantine attack and wormhole attack. Wormhole attack is one of most important attack and having great attention in recent year. Wormhole attack, demonstrate a illusion over the network that show two far away node to be an neighbor node and attracted all traffic by presenting an greediness of shortest path over the network. This paper presents a bird eye over different existing wormhole deduction mechanism and their problem.

  20. Enhancing the security of quantum secret sharing against multiphoton attack

    International Nuclear Information System (INIS)

    It is generally believed that nonorthogonal operations which can realize the state transformation between two nonorthogonal bases may ensure the security of many quantum communication protocols. However, in this paper, we present a powerful attack against quantum secret sharing protocols of these kinds. Applying entangled photons as fake signals, Eve can successfully steal the exact information without being revealed. We also give our effective modification to improve it. Under the suggested checking strategy, even to Eve's most general attack, it is robust and secure

  1. Attack on a classical analogue of the Dunjko, Wallden, Kent and Andersson quantum digital signature protocol

    OpenAIRE

    Newton, Derrick

    2015-01-01

    A quantum digital signature (QDS) protocol is investigated in respect of an attacker who can impersonate other communicating principals in the style of Lowe's attack on the Needham-Schroeder public-key authentication protocol. A man-in-the-middle attack is identified in respect of a classical variant of the protocol and it is suggested that a similar attack would be effective against the QDS protocol. The attack has been confirmed through initial protocol modelling using a automated theorem p...

  2. Simulation Analysis of DoS, MITM and CDP Security Attacks and Countermeasures

    OpenAIRE

    Tanceska, Biljana; Bogdanoski, Mitko; Risteski, Aleksandar

    2015-01-01

    In this paper, an analysis of security attacks on network elements along with the appropriate countermeasures is presented. The network topology that has been attacked is designed in GNS3 software tool installed on Windows operating system, while the attacks are performed in Kali Linux operating system. Three groups of security attacks (Denial of Service, Man in the Middle, and Control Plane attacks) are observed in simulation scenarios with a detailed analysis on each of them, followed by a ...

  3. ATTACK ON WATER BY CARBON OF SOLID FUEL

    Directory of Open Access Journals (Sweden)

    N. S. Nazarov

    2008-01-01

    Full Text Available The paper considers a continuous method for attack of high temperature water steam by carbon of solid fuel (coke. Design of water-coal gas generator and experimental stand, methodology for  measurements of parameters of water-coal gasification are described in the paper.

  4. ATTACK ON WATER BY CARBON OF SOLID FUEL

    OpenAIRE

    N. S. Nazarov; A. I. Оlevanov

    2008-01-01

    The paper considers a continuous method for attack of high temperature water steam by carbon of solid fuel (coke). Design of water-coal gas generator and experimental stand, methodology for  measurements of parameters of water-coal gasification are described in the paper.

  5. Vulnerabilities in GSM technology and feasibility of selected attacks

    Science.gov (United States)

    Voznak, M.; Prokes, M.; Sevcik, L.; Frnda, J.; Toral-Cruz, Homer; Jakovlev, Sergej; Fazio, Peppino; Mehic, M.; Mikulec, M.

    2015-05-01

    Global System for Mobile communication (GSM) is the most widespread technology for mobile communications in the world and serving over 7 billion users. Since first publication of system documentation there has been notified a potential safety problem's occurrence. Selected types of attacks, based on the analysis of the technical feasibility and the degree of risk of these weaknesses, were implemented and demonstrated in laboratory of the VSB-Technical University of Ostrava, Czech Republic. These vulnerabilities were analyzed and afterwards possible attacks were described. These attacks were implemented using open-source tools, software programmable radio USRP (Universal Software RadioPeripheral) and DVB-T (Digital Video Broadcasting - Terrestrial) receiver. GSM security architecture is being scrutinized since first public releases of its specification mainly pointing out weaknesses in authentication and ciphering mechanisms. This contribution also summarizes practically proofed and used scenarios that are performed using opensource software tools and variety of scripts mostly written in Python. Main goal of this paper is in analyzing security issues in GSM network and practical demonstration of selected attacks.

  6. Management of acute attacks of hereditary angioedema: role of ecallantide

    Science.gov (United States)

    Duffey, Hannah; Firszt, Rafael

    2015-01-01

    Hereditary angioedema (HAE) is characterized as an episodic swelling disorder with autosomal dominant inheritance. Clinical features include nonpitting edema of external or mucosal body surfaces, and patients often present with swelling of the extremities, abdominal pain, and swelling of the mouth and throat, which can lead to asphyxiation. Patients with HAE classically have no associated urticaria, which is often referred to as nonhistaminergic angioedema. Treatment for HAE involves long-term prophylaxis, short-term prophylaxis, and management of acute attacks. Up until the past few years, acute HAE episodes were predominately treated with supportive measures. Three classes of medications have recently been approved by the US Food and Drug Administration (FDA) for the management of acute HAE attacks. Ecallantide, a recombinant protein that acts as a reversible inhibitor of kallikrein, is currently indicated for acute attacks of HAE in those aged ≥12 years. In two randomized, double-blind, placebo-controlled, multicenter trials, EDEMA3 and EDEMA4, patients treated with 30 mg of ecallantide demonstrated statistically significant improvement in symptoms compared to those on placebo. In addition to its use as treatment for HAE, ecallantide has been used off label in the management of nonhistaminergic angioedema, not due to HAE. Ecallantide has shown promise in the treatment of these other forms; however, data are limited to mainly case reports at this time. Ecallantide is generally a safe and well-tolerated medication; however, based on reports of anaphylaxis, ecallantide does contain a black box warning. Due to the risk of anaphylaxis, ecallantide cannot be self-administered and must be given by a health care professional. Overall, ecallantide is a safe and effective medication for the treatment of acute attacks of HAE. PMID:25931832

  7. Evaluation of corrosion attack of chimney liners

    OpenAIRE

    Blahetová M.; Horák J.; Kubesa P.; Lasek S.; Ochodek T.

    2016-01-01

    The case study of chimney liner corrosion addresses three specific cases of damage of chimney systems from of stainless steels. These systems were used for flue of gas arising from the combustion of brown coal in small automatic boilers, which are used for heating. Detailed analyzes implied that the cause of devastating corrosion of the steel AISI 316 and 304 steel (CSN 17349, 17241) was particularly high content of halides (chlorides and fluorides), which caused a severe pitting corrosion, w...

  8. Pitch angle of galactic spiral arms

    International Nuclear Information System (INIS)

    One of the key parameters that characterizes spiral arms in disk galaxies is a pitch angle that measures the inclination of a spiral arm to the direction of galactic rotation. The pitch angle differs from galaxy to galaxy, which suggests that the rotation law of galactic disks determines it. In order to investigate the relation between the pitch angle of spiral arms and the shear rate of galactic differential rotation, we perform local N-body simulations of pure stellar disks. We find that the pitch angle increases with the epicycle frequency and decreases with the shear rate and obtain the fitting formula. This dependence is explained by the swing amplification mechanism.

  9. Impact of migraine attacks on the blood-brain barrier

    Institute of Scientific and Technical Information of China (English)

    GAO Hong-mei; LI Le; ZHANG Ke-ling; CHEN Xu-hui; TIAN Shu-qing; ZHANG Zhong-ling

    2010-01-01

    Background Cortical spreading depression can cause migraine attack, and up-regulate matrix metalloproteinase-9 (MMP-9) expression in animal. This study aimed to determine the impact on the structure and function of the blood-brain barrier by measuring plasma MMP-9 levels in patients at the acute and late stages of migraine attacks in order to elucidate the pathological mechanisms involved.Methods We recruited a case-control cohort of 38 adult migraine patients and 20 age- and gender-matched healthy control subjects. Five milliliter blood samples were collected at the acute and late stages of migraine (days 1-7), and also from the control subjects. Solid phase double antibody sandwich enzyme-linked immunosorbent assay was used to determine plasma MMP-9 levels. Statistical analysis was performed using the SAS version 9.1.Results Initial plasma MMP-9 levels of migraine patients were significantly higher than those of controls ((12.612±0.016)μg/L vs. (6.069±0.023) μg/L, respectively, P 0.05); in addition, levels were not correlated with degree of headache pain (P >0.05).Conclusions We hypothesize that migraine could lead to increased plasma MMP-9 levels resulting in blood-brain barrier damage. MMP-9 levels increase during days 1-6 of migraine attacks, peaking on day 3. Therefore, MMP-9 could be used as a biological marker to guide treatment of migraine attacks.

  10. Modelling Based Approach for Reconstructing Evidence of VOIP Malicious Attacks

    Directory of Open Access Journals (Sweden)

    Mohammed Ibrahim

    2015-05-01

    Full Text Available Voice over Internet Protocol (VoIP is a new communication technology that uses internet protocol in providing phone services. VoIP provides various forms of benefits such as low monthly fee and cheaper rate in terms of long distance and international calls. However, VoIP is accompanied with novel security threats. Criminals often take advantages of such security threats and commit illicit activities. These activities require digital forensic experts to acquire, analyses, reconstruct and provide digital evidence. Meanwhile, there are various methodologies and models proposed in detecting, analysing and providing digital evidence in VoIP forensic. However, at the time of writing this paper, there is no model formalized for the reconstruction of VoIP malicious attacks. Reconstruction of attack scenario is an important technique in exposing the unknown criminal acts. Hence, this paper will strive in addressing that gap. We propose a model for reconstructing VoIP malicious attacks. To achieve that, a formal logic approach called Secure Temporal Logic of Action(S-TLA+ was adopted in rebuilding the attack scenario. The expected result of this model is to generate additional related evidences and their consistency with the existing evidences can be determined by means of S-TLA+ model checker.

  11. Parent-Reported Predictors of Adolescent Panic Attacks.

    Science.gov (United States)

    Hayward, Chris; Wilson, Kimberly A.; Lagle, Kristy; Killen, Joel D.; Taylor, C. Barr

    2004-01-01

    Objective: To identify parent-reported risk factors for adolescent panic attacks. Method: Structured diagnostic interviews were obtained from 770 parents of participants in a school-based risk factor study for adolescent panic. Parent-reported risk factors assessed included characteristics of the child (negative affect, separation anxiety disorder…

  12. OPTIMIZATION OF TILT ANGLE FOR PHOTOVOLTAIC ARRAY

    OpenAIRE

    Ashok Kumar; N.S.Thakur,; Rahul Makade,; Maneesh Kumar Shivhar

    2011-01-01

    The performance of a solar radiation conversion system is affected by its tilt angle with the horizontal plane, thus photovoltaic array need to be tilted at the correct angle to maximize the performance of the System, This paper deals with the determination of optimum tilt angle for solar PV array in order to maximize incident solar irradiance. The model starts by calculating the monthly averaged daily solar irradiation components (direct, diffuse, ground- eflected) absorbed by the solar PV a...

  13. Evaluation of corrosion attack of chimney liners

    Directory of Open Access Journals (Sweden)

    Blahetová M.

    2016-06-01

    Full Text Available The case study of chimney liner corrosion addresses three specific cases of damage of chimney systems from of stainless steels. These systems were used for flue of gas arising from the combustion of brown coal in small automatic boilers, which are used for heating. Detailed analyzes implied that the cause of devastating corrosion of the steel AISI 316 and 304 steel (CSN 17349, 17241 was particularly high content of halides (chlorides and fluorides, which caused a severe pitting corrosion, which led up to the perforation of the liner material. Simultaneous reduction of the thickness of the used sheets was due to by the general corrosion, which was caused by the sulfur in the solid fuel. The condensation then led to acid environment and therefore the corrosion below the dew point of the sulfuric acid has occurred. All is documented by metallographic analysis and microanalysis of the corrosion products.

  14. Plasma Exchange in Severe Attacks of Neuromyelitis Optica

    Directory of Open Access Journals (Sweden)

    Mickael Bonnan

    2012-01-01

    Full Text Available Background. Neuromyelitis optica (NMO attacks are poorly controlled by steroids and evolve in stepwise neurological impairments. Assuming the strong humoral response underlying NMO attacks, plasma exchange (PLEX is an appropriate technique in severe NMO attacks. Objective. Presenting an up-to-date review of the literature of PLEX in NMO. Methods. We summarize the rationale of PLEX in relation with the physiology of NMO, the main technical aspects, and the available studies. Results. PLEX in severe attacks from myelitis or optic neuritis are associated with a better outcome, depending on PLEX delay (“time is cord and eyes”. NMO-IgG status has no influence. Finally, we build up an original concept linking the inner dynamic of the lesion, the timing of PLEX onset and the expected clinical results. Conclusion. PLEX is a safe and efficient add-on therapy in NMO, in synergy with steroids. Large therapeutic trials are required to definitely assess the procedure and define the time opportunity window.

  15. The qualitative criterion of transient angle stability

    DEFF Research Database (Denmark)

    Lyu, R.; Xue, Y.; Xue, F.;

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust of...... these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the criterions in most literatures and finds that the results could be too conservative or too optimistic. It is...

  16. A Data Mining Approach for Predicting Attacks and Recognizing Threat Strategy in the context of Collaborative Attackers and Network Security Management

    OpenAIRE

    Femi Oriola

    2014-01-01

    Data Mining has been novel in predictive modeling. In fact, various Data Mining Models have been used to predict future attacks and recognize threat strategy. However, none has been applied to predict attack and recognize threat strategy in the context of Collaborative Attacker and Victim. In recent times, Internet-facilitated Threats such as botnet and advanced persistent threats have been responsible for most successful attacks in organisations while multiple targets have been the victims o...

  17. Hydrogen attack - Influence of hydrogen sulfide. [on carbon steel

    Science.gov (United States)

    Eliezer, D.; Nelson, H. G.

    1978-01-01

    An experimental study is conducted on 12.5-mm-thick SAE 1020 steel (plain carbon steel) plate to assess hydrogen attack at room temperature after specimen exposure at 525 C to hydrogen and a blend of hydrogen sulfide and hydrogen at a pressure of 3.5 MN/sq m for exposure times up to 240 hr. The results are discussed in terms of tensile properties, fissure formation, and surface scales. It is shown that hydrogen attack from a high-purity hydrogen environment is severe, with the formation of numerous methane fissures and bubbles along with a significant reduction in the room-temperature tensile yield and ultimate strengths. However, no hydrogen attack is observed in the hydrogen/hydrogen sulfide blend environment, i.e. no fissure or bubble formation occurred and the room-temperature tensile properties remained unchanged. It is suggested that the observed porous discontinuous scale of FeS acts as a barrier to hydrogen entry, thus reducing its effective equilibrium solubility in the iron lattice. Therefore, hydrogen attack should not occur in pressure-vessel steels used in many coal gasification processes.

  18. Attitudes towards Refugees in Light of the Paris Attacks

    OpenAIRE

    Darwish, Kareem; Magdy, Walid

    2015-01-01

    The Paris attacks prompted a massive response on social media including Twitter. This paper explores the immediate response of English speakers on Twitter towards Middle Eastern refugees in Europe. We show that antagonism towards refugees is mostly coming from the United States and is mostly partisan.

  19. Behavior of Tilted Angle Shear Connectors.

    Directory of Open Access Journals (Sweden)

    Koosha Khorramian

    Full Text Available According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

  20. Prevalence of eating disorders and eating attacks in narcolepsy

    Directory of Open Access Journals (Sweden)

    Norbert Dahmen

    2008-03-01

    Full Text Available Norbert Dahmen, Julia Becht, Alice Engel, Monika Thommes, Peter TonnPsychiatry Department, University of Mainz, GermanyAbstract: Narcoleptic patients suffer frequently from obesity and type II diabetes. Most patients show a deficit in the energy balance regulating orexinergic system. Nevertheless, it is not known, why narcoleptic patients tend to be obese. We examined 116 narcoleptic patients and 80 controls with the structured interview for anorectic and bulimic eating disorders (SIAB to test the hypothesis that typical or atypical eating attacks or eating disorders may be more frequent in narcoleptic patients. No difference in the current prevalence of eating disorders bulimia nervosa, binge eating disorder, or anorexia nervosa was found, nor was the frequency of eating attacks higher in the narcolepsy group. We conclude that present eating disorders and eating attacks as defined in DSM IV are not the reason for the observed differences in body composition. Additional factors, such as basal metabolic rates and lifestyle factors need to be considered.Keywords: narcolepsy, eating disorder, SIAB, bulimia, anorexia, eating attack

  1. Low Serum Concentrations of Vitamin B6 and Iron Are Related to Panic Attack and Hyperventilation Attack

    OpenAIRE

    Mikawa, Yasuhito; Mizobuchi, Satoshi; Egi, Moritoki; Morita, Kiyoshi

    2013-01-01

    Patients undergoing a panic attack (PA) or a hyperventilation attack (HVA) are sometimes admitted to emergency departments (EDs). Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6) and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. ...

  2. A Case of Brucellosis with Recurrent Attacks of Vasculitis

    OpenAIRE

    Pınar Korkmaz; Mehtap Kıdır; Nazlı Dizen Namdar; Ahmet Özmen; Cemile Uyar; Ayşe Nur Değer

    2016-01-01

    Brucellosis is a zoonosis that affects several organs or systems. Skin involvement is nonspecific and it is reported to range between 0,4 and 17% of the patients with brucellosis. Here, we defined a 36-year-old female patient presented to our clinic with a clinical picture of recurrent attacks of vasculitis due to brucellosis for the first time. Skin involvement and vasculitic lesions as a finding of skin involvement are nonspecific in brucellosis. Therefore, in the regions like Turkey where ...

  3. Detection techniques of selective forwarding attacks in wireless sensor networks: a survey

    CERN Document Server

    Sharma, Preeti; Saluja, Krishan Kumar

    2012-01-01

    The wireless sensor network has become a hot research area due its wide range of application in military and civilian domain, but as it uses wireless media for communication these are easily prone to security attacks. There are number of attacks on wireless sensor networks like black hole attack, sink hole attack, Sybil attack, selective forwarding attacks etc. in this paper we will concentrate on selective forwarding attacks In selective forwarding attacks, malicious nodes behave like normal nodes and selectively drop packets. The selection of dropping nodes may be random. Identifying such attacks is very difficult and sometimes impossible. In this paper we have listed up some detection techniques, which have been proposed by different researcher in recent years, there we also have tabular representation of qualitative analysis of detection techniques

  4. DETECTION TECHNIQUES OF SELECTIVE FORWARDING ATTACKS IN WIRELESS SENSOR NETWORKS : A SURVEY

    Directory of Open Access Journals (Sweden)

    Preeti Sharma

    2012-05-01

    Full Text Available The wireless sensor network has become a hot research area due its wide range of application in military and civilian domain, but as it uses wireless media for communication these are easily prone to security attacks. There are number of attacks on wireless sensor networks like black hole attack, sink hole attack ,Sybil attack ,selective forwarding attacks etc. in this paper we will concentrate on selective forwarding attacks In selective forwarding attacks, malicious nodes behave like normal nodes and selectively drop packets. The selection of dropping nodes may be random. Identifying such attacks is very difficult and sometimes impossible. In this paper we have listed up some detection techniques, which have been proposed by different researcher in recent years, there we also have tabular representation of qualitative analysis of detection techniques

  5. A Method of Detecting Sql Injection Attack to Secure Web Applications

    Directory of Open Access Journals (Sweden)

    Manesh T

    2012-12-01

    Full Text Available Web applications are becoming an important part of our daily life. So attacks against them also increasesrapidly. Of these attacks, a major role is held by SQL injection attacks (SQLIA. This paper proposes anew method for preventing SQL injection attacks in JSP web applications. The basic idea is to checkbefore execution, the intended structure of the SQL query. For this we use semantic comparison. Ourfocus is on stored procedure attack in which query will be formed within the database itself and sodifficult to extract that query structure for validation. Also this attack is less considered in the literature.

  6. DEF: As a form of sulfate attack

    OpenAIRE

    Skalny, J.; Johansen, V.; Thaulow, N.; Palomo, A., Krivenko, P.,

    1996-01-01

    Delayed ettringite formation (DEF) is the term used to describe expansion of some heat cured portland cement concretes. Although meaningful progress has been made, the exact mechanism of the expansion itself is not entirely understood. The ettringite reformation is enabled, primarily, by thermal decomposition of ettringite formed prior to or during the cement paste setting as a result of excessive/improper heat curing. Observance in mature concrete of crystalline ettringite in air voids, crac...

  7. Prevention of Spoofing Attacks in the Infrastructure Wireless Networks

    Directory of Open Access Journals (Sweden)

    Samraa A. AlAsady

    2012-01-01

    Full Text Available Problem statement: Spoofing Attack is one of the vulnerabilities in the wireless networks, which is a situation in which the intruder successfully masquerades as legal one. Spoofing Attacks will decrease the performance of the network and violate many security issues. In the networks that use MAC address based filtering approach to authenticate the clients, the spoofer just needs to get a valid MAC address that belong to some authorized client in the network in order to gain an illegitimate advantage. Approach: In this article, it has proposed an algorithm that uses an additional authentication process beside MAC address filtering and periodically re-authenticates the client after sending every specific number of Data frames. The proposed additional authentication process is based on two parts. First: Using unique information that belongs to every client in the network such as computer name, CPU ID and the current time as inputs to a hash function (one-way function, then insert the hash value in the slack fields of the header of the frame (Steganography. Second: Make a modification to the access point access control list by adding that unique information belong to each client in addition to its MAC address in the access control list. Thus, when the AP receives an Authentication frame from a client, it will first check the MAC address, if it is legal; the AP will re-compute the Hash value depending on the corresponding identifiers stored in the access control list and the time of creating the frame, then compare the resulted hash value with the received one and decide whether to reject or accept the access. Results: The results has been found is that even the attacker is spoofed the MAC address; he/she cannot communicate with the network because the attacker will fail in computing the hash value that depends on the Computer name and CPU ID. Also the attacker will be prevented even if he/she enters the network after the legal client finished the

  8. Relay attacks of NFC smart cards

    OpenAIRE

    Chu, Xiqing

    2014-01-01

    Near Field Communication (NFC) is a set of standards, which allows two devices to transfer messages over a short range of distance of 10 cm. NFC based smart cards and applications are widely used for public transportation, ticketing system and security critical identity cards. NFC contains mainly two proximity smart card specifications ISO 14443 and ISO 18092 for lower level data exchange. However, none of the specifications above provides security mechanism to protect communication between s...

  9. A Serious Cause of Panic Attack

    Directory of Open Access Journals (Sweden)

    Michael O'Connell

    2012-01-01

    Full Text Available We report on a case of a patient with atrial fibrillation in the setting of Wolff-Parkinson-White syndrome. The patient underwent synchronized electrical cardioversion, typically considered safe and effective, which resulted in a dangerous complication for the patient (degeneration into ventricular fibrillation. Discussion of common rhythm disturbances in WPW and management strategies are reviewed.

  10. A Serious Cause of Panic Attack

    OpenAIRE

    Michael O'Connell; Aaron Bernard

    2012-01-01

    We report on a case of a patient with atrial fibrillation in the setting of Wolff-Parkinson-White syndrome. The patient underwent synchronized electrical cardioversion, typically considered safe and effective, which resulted in a dangerous complication for the patient (degeneration into ventricular fibrillation). Discussion of common rhythm disturbances in WPW and management strategies are reviewed.

  11. Analysis of signature wrapping attacks and countermeasures

    DEFF Research Database (Denmark)

    Gajek, Sebastian; Jensen, Meiko; Liao, Lijun;

    2009-01-01

    In recent research it turned out that Boolean verification, of digital signatures in the context of WSSecurity, is likely to fail: If parts of a SOAP message, are signed and the signature verification applied to, the whole document returns true, then nevertheless the, document may have been signi......, that this solution is both efficient and secure. © 2009 IEEE....

  12. Study of attack in college volleyball

    Directory of Open Access Journals (Sweden)

    Yordan Portela Pozo

    2014-03-01

    Full Text Available AbstractThis work is done in order to analyze the positive and negative aspects that affected the performance of the auction action in volleyball players performing this action (in this case male in the Provincial University Games in 2012 in Havana , for which I take as a case study to the players of the University of Information Sciences and its opponents in those games, completing a total of 268 shares auctions in 7 games with a total of 15 September analyzed taking account of changes in the sport of Volleyball university in Cuba, data recorded by an observation sheet previously completed by the authors. The main results in this paper show that the greatest amount of shots that were done in these games were diagonal and a good percentage of positive linear auctions however were few and with very poor results. The primary role of the auction for the game's success is fully confirmed in this work because this action is achieved through many points in the game of volleyball and thus leads to a better result.

  13. Intrusion Detection of NSM Based DoS Attacks Using Data Mining in Smart Grid

    OpenAIRE

    JungChan Na; Kijoon Chae; Mihui Kim; Shi Li; Xinyi Chen; Kyung Choi

    2012-01-01

    In this paper, we analyze the Network and System Management (NSM) requirements and NSM data objects for the intrusion detection of power systems; NSM is an IEC 62351-7 standard. We analyze a SYN flood attack and a buffer overflow attack to cause the Denial of Service (DoS) attack described in NSM. After mounting the attack in our attack testbed, we collect a data set, which is based on attributes for the attack. We then run several data mining methods with the data set using the Waikato Envir...

  14. STUDY OF PRIVILEGE ESCALATION ATTACK ON ANDROID AND ITS COUNTERMEASURES

    OpenAIRE

    REJO MATHEW

    2012-01-01

    Android is most commonly used platform for smartphones today which boasts of an advanced security model having MAC and sandboxing. These features allow developers and users to restrict the execution of anapplication to the privileges assigned. The exploitation of vulnerabilities of the program is confined within the privilege boundaries of an applications sandbox. Privilege escalation attacks have grown manifold as the use of android systems have increased. Different kinds of mechanisms have ...

  15. Orientation of planes shown up by ionic attack (1961)

    International Nuclear Information System (INIS)

    Certain recent experiments have shown that ions of low energy (3 to 15 kV), as different in nature as oxygen and argon, produced a selective attack on metallic surfaces and thus revealed certain planes of the crystal lattice of the sample bombarded. The aim of this work is to study the orientation of these planes as a function of the direction of the ions. (authors)

  16. Understand Your Risk of Heart Attack

    Science.gov (United States)

    ... in a person's life, their health behaviors and socioeconomic status. These factors may affect established risk factors. For ... but are lower in calories — over nutrient-poor foods. Choose a diet that emphasizes intake of vegetables, ... in Women 7 Tachycardia | Fast Heart Rate 8 Warning Signs of a Heart ...

  17. Case studies of attacks on communication networks

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sin Bok; Han, Eon Suk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-15

    Recently, as the computer hardware and communications are developed, the data exchange through inter-networking has been highlighted and the data is being recognized as a great asset. Most of the organizations, businesses and enterprises are open to the external world-computer communication networks, attention must be focused on the securities of the information infrastructure. A government organization has been developing 'Circuits Analyzers', and 'Hacker-Tracking Program' and is struggling to track down sneakers. In this report, we analyze the contents of the cases where the communication network has been invaded, from the past up until now in Korea. This report also contains the result of a study on E-mail security, for the protection of KAERI Integrated Management Information System under which utilizes the CALS concepts and web services. (Author)

  18. Case studies of attacks on communication networks

    International Nuclear Information System (INIS)

    Recently, as the computer hardware and communications are developed, the data exchange through inter-networking has been highlighted and the data is being recognized as a great asset. Most of the organizations, businesses and enterprises are open to the external world-computer communication networks, attention must be focused on the securities of the information infrastructure. A government organization has been developing 'Circuits Analyzers', and 'Hacker-Tracking Program' and is struggling to track down sneakers. In this report, we analyze the contents of the cases where the communication network has been invaded, from the past up until now in Korea. This report also contains the result of a study on E-mail security, for the protection of KAERI Integrated Management Information System under which utilizes the CALS concepts and web services. (Author)

  19. Conestat alfa for the treatment of angioedema attacks

    Directory of Open Access Journals (Sweden)

    Davis B

    2011-07-01

    Full Text Available Benjamin Davis, Jonathan A BernsteinUniversity of Cincinnati College of Medicine, Department of Internal Medicine, Division of Immunology/Allergy Section, Cincinnati, OH, USAAbstract: Recently, multiple C1 inhibitor (C1-INH replacement products have been approved for the treatment of hereditary angioedema (HAE. This review summarizes HAE and its current treatment modalities and focuses on findings from bench to bedside trials of a new C1-INH replacement, conestat alfa. Conestat alfa is unique among the other C1-INH replacement products because it is produced from transgenic rabbits rather than derived from human plasma donors, which can potentially allow an unlimited source of drug without any concern of infectious transmission. The clinical trial data generated to date indicate that conestat alfa is safe and effective for the treatment of acute HAE attacks.Keywords: androgens, adverse events, patients, HAE attacks 

  20. STUDY OF PRIVILEGE ESCALATION ATTACK ON ANDROID AND ITS COUNTERMEASURES

    Directory of Open Access Journals (Sweden)

    REJO MATHEW

    2012-09-01

    Full Text Available Android is most commonly used platform for smartphones today which boasts of an advanced security model having MAC and sandboxing. These features allow developers and users to restrict the execution of anapplication to the privileges assigned. The exploitation of vulnerabilities of the program is confined within the privilege boundaries of an applications sandbox. Privilege escalation attacks have grown manifold as the use of android systems have increased. Different kinds of mechanisms have provided some sort of respite to the developers but the security feature handling by the developers has not helped much. In this paper we discuss the basics of the privilege escalation attack and the various techniques used to counter and prevent this problem.

  1. DEF: As a form of sulfate attack

    Directory of Open Access Journals (Sweden)

    Skalny, J.

    1996-12-01

    Full Text Available Delayed ettringite formation (DEF is the term used to describe expansion of some heat cured portland cement concretes. Although meaningful progress has been made, the exact mechanism of the expansion itself is not entirely understood. The ettringite reformation is enabled, primarily, by thermal decomposition of ettringite formed prior to or during the cement paste setting as a result of excessive/improper heat curing. Observance in mature concrete of crystalline ettringite in air voids, cracks, and gaps around the aggregate is not in itself an evidence for DEF, but is the consequence of natural recrystallization of ettringite into available larger spaces. Occurance of DEF is dependent on materials, curing, and environmental conditions, and can easily be distinguished from ASR and other deterioration mechanisms by optical and electron-optical methods.

    DEF es el término habitualmente usado para describir la expansión que sufren algunos hormigones de cemento Portland que han sido curados con la ayuda de un tratamiento térmico. DEF es la abreviatura de la expresión inglesa "Delayed Ettringite Formation" que en español se podría traducir como "Formación de Etringita Retrasada". Aunque en los últimos tiempos se ha progresado significativamente, aún hoy día no se entiende completamente el mecanismo exacto de la expansión en sí misma. La formación de una etringita tardía es, en principio, consecuencia de la descomposición térmica de la etringita formada con anterioridad o durante el fraguado de la pasta de cemento, por un exceso de calor o inadecuado proceso de curado térmico. La observación, en el hormigón maduro, de etringita cristalina en poros, fisuras y en las interfases pasta-áridos no es en sí una evidencia de la DEF, pero sí es una consecuencia de la natural recristalización de la etringita en espacios disponibles. El fenómeno de la DEF depende de los materiales, del curado y de las condiciones ambientales, y puede

  2. Open-label, multicenter study of self-administered icatibant for attacks of hereditary angioedema

    DEFF Research Database (Denmark)

    Aberer, W; Maurer, M; Reshef, A; Longhurst, H; Kivity, S; Bygum, Anette; Caballero, T; Bloom, B; Nair, N; Malbrán, A

    2014-01-01

    Historically, treatment for hereditary angioedema (HAE) attacks has been administered by healthcare professionals (HCPs). Patient self-administration could reduce delays between symptom onset and treatment, and attack burden. The primary objective was to assess the safety of self...

  3. A Study of Black Hole Attack on MANET Performance

    Directory of Open Access Journals (Sweden)

    C. K. Nagpal

    2012-08-01

    Full Text Available Mobile Ad hoc Network (MANET is a self-organized wireless network, consisting of nodes (mobile devices responsible for its creation, operation and maintenance. The communication in the MANET is of multihop in nature due to absence of any fixed infrastructure. An attacker may intrude easily into MANET by posing as legitimate intermediate node and present various types of security attacks on data exchanges taking place between source and destination. In this paper we study the impact of presence of black hole node on MANET performance on the basis of reachability, hop count, neighbor node density and path optimality. We observe that as the percentage of black hole nodes increases, the MANET performance degrades significantly.

  4. Distributed Detection of Wormhole Attacks in Wireless Sensor Networks

    Science.gov (United States)

    de Graaf, Rennie; Hegazy, Islam; Horton, Jeffrey; Safavi-Naini, Reihaneh

    Sensors in a wireless sensor network depend on their neighbours to route their messages. Yet, routing protocols in wireless sensor network are vulnerable to different types of attacks. In this paper, we consider the wormhole attack in which the adversary diverts traffic from one part of the network to another part by introducing a low cost tunnel between the two parts. We introduce a distributed intrusion detection system that monitors the communication in the network and propose a criterion for the placement of intrusion detection nodes. The intrusion detection system searches for violations of that criterion to detect wormholes of length above a certain minimum value. We evaluate the effectiveness of our system in a simulated environment. The experiments show that our system can detect 100% of the wormholes that are beyond the communication range of the intrusion detection nodes. Finally, we discuss our results and show directions for future work.

  5. Attacks to cryptography protocols of wireless industrial communication systems

    OpenAIRE

    Ondrašina, Tomáš; Franeková, Mária

    2010-01-01

    The paper deals with problems of safety and security principles within wireless industrial communication systems. First safety requirements to wireless industrial communication system, summarisation of attack methods and the available measures for risks elimination are described with orientation to safety critical applications. The mainly part is oriented to identification of risks and summarisation of defensive methods of wireless communication based on cryptographic techniques. Practical pa...

  6. The Determinants of Technological Change in Heart Attack Treatment

    OpenAIRE

    David M. Cutler; Mark McClellan

    1996-01-01

    This paper examines the sources of expenditure growth in heart attack treatment. We first show that essentially all of cost growth is a result of the diffusion of particular intensive technologies; the prices paid for a given level of technology have been constant or falling over time. We then examine the reasons for this technology diffusion. We distinguish six factors that may influence technology diffusion: organizational factors within hospitals; the insurance environment in which technol...

  7. Performance analyses of wormhole attack in Cognitive Radio Network (CRN

    Directory of Open Access Journals (Sweden)

    Prabhjot

    2015-06-01

    Full Text Available Mobile wirelesses networks are generally open to various attacks like information and physical security attacks than fixed wired networks. Securing wireless ad hoc networks is particularly more difficult for many of the reasons for example vulnerability of channels and nodes, absence of infrastructure, dynamically changing topology etc. After that we initialize the number of nodes. Then implement protocol for the communication of nodes. Due to these protocols communication start. And this will be then implemented in CRNs which stand for cognitive radio network in which channel sensing is done. By the use of CRN security will be improved and performance will be enhanced. Find the malicious nodes occur in the network. One malicious node uses routing protocol to claim itself of being shortest path to last node but drops routing packets and doesn’t send packets to its neighbors. In last evaluate the parameters.

  8. Applying the Principles of Homicide by Heart Attack.

    Science.gov (United States)

    Hlavaty, Leigh; Sung, LokMan

    2016-06-01

    Homicide by heart attack is a well-established model in forensic pathology that describes death elicited during or immediately after a criminal act where a threat or fear of physical injury is present. After its introduction nearly 4 decades ago, the principle has undergone a handful of modifications but still maintains its core concepts. All cases of this nature during a 20-year period at the Wayne County Medical Examiner's Office were compared and contrasted for demographics, circumstances and scene investigation, and autopsy and toxicology findings. Of the cases fulfilling the previously established criteria for homicide by heart attack, more than 80% displayed significant changes because of hypertension. This finding coincides with the high prevalence of hypertension in our urban population and highlights the significance of this disease. Also present were minor external and internal injuries in select cases, which reinforce the understanding that physical contact between the decedent and assailant does not preclude this diagnosis. PMID:27049661

  9. Analysis of factors affecting angle ANB.

    Science.gov (United States)

    Hussels, W; Nanda, R S

    1984-05-01

    Cephalometric analyses based on angular and linear measurements have obvious fallacies, which have been discussed in detail by Moyers and Bookstein. However, the clinical application of such an analysis by the orthodontic profession in treatment planning is widely accepted. Variations of angle ANB are commonly used to determine relative jaw relationships in most of the cephalometric evaluations. Several authors, including points A and B influences angle ANB, as does rotational growth of the upper and lower jaws. In addition, the authors point out that growth in a vertical direction (distance N to B) and an increase of the dental height (distance A to B) may contribute to changes in angle ANB. For a Class I relation (Wits = 0 mm), a mathematical formula has been developed which enables the authors to study the geometric influence of angle ANB caused by the following four effects: (1) rotation of the jaws and/or occlusal plane relative to the anterior cranial base; (2) anteroposterior position of N relative to point B, (3) vertical growth (distance N to B); (4) increase in dental height (distance A to B). It was observed that, contrary to the common belief that an ANB angle of 2 +/- 3.0 degrees is considered normal for a skeletal Class I relation, the calculated values of angle ANB will vary widely with changes in these four controlling factors under the same skeletal Class I conditions (Wits = 0 mm). Therefore, in a case under consideration, angle ANB must be corrected for these geometric effects in order to get a proper perspective of the skeletal discrepancy. This is facilitated by comparing the measured ANB angle with the corresponding ANB angle calculated by a formula for a Class I relationship. The corresponding calculated angle ANB can be taken from the tables which are based upon the formula using the same values for SNB, omega (angle between occlusal plane and anterior cranial base), b (which is distance N to B) and a (dental height measured as perpendicular

  10. Classification of artificial intelligence ids for smurf attack

    CERN Document Server

    Ugtakhbayar, N; Sodbileg, Sh

    2012-01-01

    Many methods have been developed to secure the network infrastructure and communication over the Internet. Intrusion detection is a relatively new addition to such techniques. Intrusion detection systems (IDS) are used to find out if someone has intrusion into or is trying to get it the network. One big problem is amount of Intrusion which is increasing day by day. We need to know about network attack information using IDS, then analysing the effect. Due to the nature of IDSs which are solely signature based, every new intrusion cannot be detected; so it is important to introduce artificial intelligence (AI) methods / techniques in IDS. Introduction of AI necessitates the importance of normalization in intrusions. This work is focused on classification of AI based IDS techniques which will help better design intrusion detection systems in the future. We have also proposed a support vector machine for IDS to detect Smurf attack with much reliable accuracy.

  11. Resilience of LTE networks against smart jamming attacks

    KAUST Repository

    Aziz, Farhan M.

    2014-12-08

    Commercial LTE networks are being studied for mission-critical applications, such as public safety and smart grid communications. In this paper, LTE networks are shown vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers, who may employ simple narrowband jamming techniques to attack without any need to hack the network or its users. We modeled the utilities of jamming and anti-jamming actions played by the jammer and the network under the framework of single-shot and repeated Bayesian games. In a single-shot game formulation the only Nash Equilibria (NE) are pure strategy equilibria at which network utility is severely compromised. We propose a repeated-game learning and strategy algorithm for the network that outperforms single-shot games by a significant margin. Furthermore, all of our proposed actions and algorithms can be implemented with current technology.

  12. Active Linkability Attacks

    OpenAIRE

    Schnoor, Henning; Woizekowski, Oliver

    2013-01-01

    We study linking attacks on communication protocols. We show that an active attacker is strictly more powerful in this setting than previously-considered passive attackers. We introduce a formal model to reason about active linkability attacks, formally define security against these attacks and give very general conditions for both security and insecurity of protocols. In addition, we introduce a composition-like technique that allows to obtain security proofs by only studying small component...

  13. Web Application Scanning and Identification of Vulnerabilities for Different Attacks

    Directory of Open Access Journals (Sweden)

    Haridas V.Kanure,

    2014-05-01

    Full Text Available Now days there are lots of websites present in internet. And providing different services to the client is not only important task for website owner but also protecting their website from different attacks. Now days Identification of vulnerabilities in web application is becoming serious issue. Protecting website by identifying vulnerabilities and taking important attack prevention steps is very much important task.Different vulnerabilities identification is based on different test cases which we have and which we are going to build by use of this tool. Those test cases come from combination of some effective code. SQL injection test case can work with effective database query. And Cross site scripting can works with some java script code or other scripting language code etc.

  14. Robustness of onion-like correlated networks against targeted attacks

    CERN Document Server

    Tanizawa, Toshihiro; Stanley, H Eugene

    2011-01-01

    Recently, it was found by Schneider et al. [Proc. Natl. Acad. Sci. USA, 108, 3838 (2011)], using simulations, that scale-free networks with "onion structure" are very robust against targeted high degree attacks. The onion structure is a network where nodes with almost the same degree are connected. Motivated by this work, we propose and analyze, based on analytical considerations, an onion-like candidate for a nearly optimal structure against simultaneous random and targeted high degree node attacks. The nearly optimal structure can be viewed as a hierarchically interconnected random regular graphs, the degrees and populations of which are specified by the degree distribution. This network structure exhibits an extremely assortative degree-degree correlation and has a close relationship to the "onion structure." After deriving a set of exact expressions that enable us to calculate the critical percolation threshold and the giant component of a correlated network for an arbitrary type of node removal, we apply...

  15. Management of acute attacks of hereditary angioedema: role of ecallantide

    Directory of Open Access Journals (Sweden)

    Duffey H

    2015-04-01

    Full Text Available Hannah Duffey,1 Rafael Firszt1,2 1Department of Pediatrics, 2Division of Allergy, Immunology and Rheumatology, University of Utah, Salt Lake City, UT, USA Abstract: Hereditary angioedema (HAE is characterized as an episodic swelling disorder with autosomal dominant inheritance. Clinical features include nonpitting edema of external or mucosal body surfaces, and patients often present with swelling of the extremities, abdominal pain, and swelling of the mouth and throat, which can lead to asphyxiation. Patients with HAE classically have no associated urticaria, which is often referred to as nonhistaminergic angioedema. Treatment for HAE involves long-term prophylaxis, short-term prophylaxis, and management of acute attacks. Up until the past few years, acute HAE episodes were predominately treated with supportive measures. Three classes of medications have recently been approved by the US Food and Drug Administration (FDA for the management of acute HAE attacks. Ecallantide, a recombinant protein that acts as a reversible inhibitor of kallikrein, is currently indicated for acute attacks of HAE in those aged 12 years. In two randomized, double-blind, placebo-controlled, multicenter trials, EDEMA3 and EDEMA4, patients treated with 30 mg of ecallantide demonstrated statistically significant improvement in symptoms compared to those on placebo. In addition to its use as treatment for HAE, ecallantide has been used off label in the management of nonhistaminergic angioedema, not due to HAE. Ecallantide has shown promise in the treatment of these other forms; however, data are limited to mainly case reports at this time. Ecallantide is generally a safe and well-tolerated medication; however, based on reports of anaphylaxis, ecallantide does contain a black box warning. Due to the risk of anaphylaxis, ecallantide cannot be self-administered and must be given by a health care professional. Overall, ecallantide is a safe and effective medication for the

  16. Evaluation of Popcorn Germplasm for Resistance to Sesamia nonagrioides Attack

    OpenAIRE

    Revilla Temiño, Pedro; Butrón Gómez, Ana María; Sandoya Miranda, Germán; Malvar Pintos, Rosa Ana; Ordás Pérez, Amando

    2005-01-01

    Popcorn adapted to Spanish conditions could be an interesting and profitable alternative to field corn. However, little is known about breeding popcorn germplasm for adaptation to Spain. Sesamia nonagrioides Lefèvbre is the main insect pest affecting popcorn quality and yield under Spanish growing conditions. The objectives of the study were the search for sources of resistance to S. nonagrioides among popcorn germplasm and to study the genetics of the resistance to S. nonagrioides attack. Ei...

  17. Attacks of Asthma due to Chlorinized Water: Case Report

    OpenAIRE

    Murat Eyup Berdan; Ercan Gocgeldi; Sami Ozturk; Ali Kutlu

    2008-01-01

    The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure ...

  18. Investigation of Sulfate Attack by Experimental and Thermodynamic Means

    OpenAIRE

    Kunther, Wolfgang

    2012-01-01

    This work investigates sulfate attack in complex sulfate environments by exposing different binder types to various sulfate solutions and comparing predicted phase and volume changes with experimental data. The most important aspects of this work can be grouped in three topics: The comparison of the predicted volume increase with the experimentally observed length changes. This part of the work shows that volume increase cannot be linked direct...

  19. Robustness of networks against propagating attacks under vaccination strategies

    CERN Document Server

    Hasegawa, Takehisa

    2011-01-01

    We study the effect of vaccination on robustness of networks against propagating attacks that obey the susceptible-infected-removed model. By extending the generating function formalism developed by Newman (2005), we analytically determine the robustness of networks that depends on the vaccination parameters. We consider the random defense where nodes are vaccinated randomly and the degree-based defense where hubs are preferentially vaccinated. We apply the obtained results to the random graph and scale-free networks.

  20. Robustness of networks against propagating attacks under vaccination strategies

    International Nuclear Information System (INIS)

    We study the effect of vaccination on the robustness of networks against propagating attacks that obey the susceptible–infected–removed model. By extending the generating function formalism developed by Newman (2005 Phys. Rev. Lett. 95 108701), we analytically determine the robustness of networks that depends on the vaccination parameters. We consider the random defense where nodes are vaccinated randomly and the degree-based defense where hubs are preferentially vaccinated. We show that, when vaccines are inefficient, the random graph is more robust against propagating attacks than the scale-free network. When vaccines are relatively efficient, the scale-free network with the degree-based defense is more robust than the random graph with the random defense and the scale-free network with the random defense

  1. Classification of Artificial Intelligence IDS for Smurf Attack

    OpenAIRE

    N.Ugtakhbayar; D.Battulga; Sh.Sodbileg

    2012-01-01

    Many methods have been developed to secure the network infrastructure and communication over the Internet. Intrusion detection is a relatively new addition to such techniques. Intrusion detection systems (IDS) are used to find out if someone has intrusion into or is trying to get it the network. One big problem is amount of Intrusion which is increasing day by day. We need to know about network attack information using IDS, then analysing the effect. Due to the nature of IDSs whic...

  2. Animal attack: an unusual case of multiple trauma in childhood.

    LENUS (Irish Health Repository)

    O'Grady, E

    2014-11-01

    A 2½ year old girl attended our facility following attack by a tapir at a city zoo. She sustained multiple injuries including a forearm laceration and multiple perforating wounds to her abdominal wall. She had several procedures, including bowel resection, performed under the care of the General Paediatric Surgery and Plastic Surgery teams and was treated with a course of IV antibiotics. She recovered well and to date has suffered no long-term adverse outcome.

  3. Detection Techniques of DOS/DDOS/DRDOS Attacks in Networks of Mass Service

    Directory of Open Access Journals (Sweden)

    G. Shangytbayeva

    2015-08-01

    Full Text Available The study describes the basic network attacks such as "denial of service", algorithm of operation of malefactors with attacks of this type, techniques of detection of DOS/DDOS/DRDOS attacks in networks of mass service. For detection of DDoS-attacks is offered the valuation method of probability of loss of arbitrary request in case of its passing on networks of mass service. Developed the architecture and constructed program implementation of system of detection of DDoS-attacks. The developed technique allows to receive an adequate assessment of frequency of loss of requests on a network if the network of mass service is in the stationary mode.

  4. Mass Change Prediction Model of Concrete Subjected to Sulfate Attack

    Directory of Open Access Journals (Sweden)

    Kwang-Myong Lee

    2015-01-01

    Full Text Available The present study suggested a mass change prediction model for sulfate attack of concrete containing mineral admixtures through an immersion test in sulfate solutions. For this, 100% OPC as well as binary and ternary blended cement concrete specimens were manufactured by changing the types and amount of mineral admixture. The concrete specimens were immersed in fresh water, 10% sodium sulfate solution, and 10% magnesium sulfate solution, respectively, and mass change of the specimens was measured at 28, 56, 91, 182, and 365 days. The experimental results indicated that resistance of concrete containing mineral admixture against sodium sulfate attack was far greater than that of 100% OPC concrete. However, in terms of resistance against magnesium sulfate attack, concrete containing mineral admixture was lower than 100% OPC concrete due to the formation of magnesium silicate hydrate (M-S-H, the noncementitious material. Ultimately, based on the experimental results, a mass change prediction model was suggested and it was found that the prediction values using the model corresponded relatively well with the experimental results.

  5. A lattice determination of gA and left angle x right angle from overlap fermions

    International Nuclear Information System (INIS)

    We present results for the nucleon's axial charge gA and the first moment left angle x right angle of the unpolarized parton distribution function from a simulation of quenched overlap fermions. (orig.)

  6. Development of an accelerated test for Internal Sulfate Attack study

    OpenAIRE

    Khelil Nacim; Aubert Jean-Emmanuel; Escadeillas Gilles

    2014-01-01

    Internal Sulfate Attack (ISA) is a pathology that occurs under certain conditions in concrete having undergone heating above 70 °C at early age (through heating in pre-casting industry or due to hydration in large concrete parts). This reaction deemed very slow, numerous methods to speed up reactions leading to delayed ettringite formation have been developed. These methods are all based on the material damage. Another type of test is currently under development. It is based on rehabilitation...

  7. The Principles of Modern Attacks Analysis for Penetration Tester

    Directory of Open Access Journals (Sweden)

    Adam Ali.Zare Hudaib

    2015-03-01

    Full Text Available Modern cyber defense requires a realistic and thorough understanding of web application security issues. Anyone can learn to sling a few web hacks, but web application penetration testing requires something deeper. Major web application flaws and their exploitation, a field-tested and repeatable process to consistently finding these flaws and convey them will be discussed in this article. Modern attacks principles will be analyzed on purpose to create the most sufficient penetration tests.

  8. FPGA Implementation of a Statistical Saturation Attack against PRESENT

    OpenAIRE

    Kerckhof, Stéphanie; Collard, Baudoin; Standaert, François-Xavier; AFRICACRYPT 2011

    2011-01-01

    Statistical attacks against block ciphers usually exploit “characteristics”. A characteristic essentially defines a relation between (parts of) the block cipher’s inputs, outputs and intermediate values. Intuitively, a good characteristic is one for which the relation between the cipher’s inputs and outputs exhibit a significant deviation from the uniform distribution. Due to its intensive computational complexity, the search for good characteristics generally relies on heuristics, e.g. based...

  9. High Doses of Fish Oil Might Help Healing After Heart Attack

    Science.gov (United States)

    ... Doses of Fish Oil Might Help Healing After Heart Attack Study found improved heart function, less scarring To ... 2, 2016 MONDAY, Aug. 1, 2016 (HealthDay News) -- Heart attack patients who took high doses of fish oil ...

  10. Breast Cancer Meds Won't Raise Chances of Heart Attack, Stroke, Study Suggests

    Science.gov (United States)

    ... nlm.nih.gov/medlineplus/news/fullstory_158441.html Breast Cancer Meds Won't Raise Chances of Heart Attack, ... the risk of heart attacks and strokes among breast cancer survivors, a new study suggests. However, the researchers ...

  11. Hydrogen attack of thick section pressure vessel steels

    International Nuclear Information System (INIS)

    The thick section pressure vessel steels, A387 2.25Cr-1Mo; A533B Mn-Mo-Ni steel and modifications containing MnNiCr and MnCrSi respectively, have been exposed to hydrogen atmospheres at 550 C, of 10 MPa or 13.8 MPa pressure, for periods of 500 hours and 1000 hours. At the lower pressure, the Mn-Mo-Ni steels, which contained predominantly M3C carbides, showed macroscopic blisters and extensive grain boundary cavities in the as-received and 0.7Mn modified conditions, but revealed very little damage when modified with 1% chromium. No hydrogen attack damage was observed in the 2.25Cr-1Mo modifications at 10 MPa. At higher pressure, the Mn-Mo-Ni steels showed extensive hydrogen attack damage. The 2.25Cr-1Mo steels are considerably less damaged by hydrogen attack than are the Mn-Mo-Ni steel and its modifications. Mechanical properties for a series of alloy modifications are presented and related to the stability of the microstructure and the heat treatment conditions

  12. Identifying optimal targets of network attack by belief propagation

    Science.gov (United States)

    Mugisha, Salomon; Zhou, Hai-Jun

    2016-07-01

    For a network formed by nodes and undirected links between pairs of nodes, the network optimal attack problem aims at deleting a minimum number of target nodes to break the network down into many small components. This problem is intrinsically related to the feedback vertex set problem that was successfully tackled by spin-glass theory and an associated belief propagation-guided decimation (BPD) algorithm [Zhou, Eur. Phys. J. B 86, 455 (2013), 10.1140/epjb/e2013-40690-1]. In the present work we apply the BPD algorithm (which has approximately linear time complexity) to the network optimal attack problem and demonstrate that it has much better performance than a recently proposed collective information algorithm [Morone and Makse, Nature 524, 65 (2015), 10.1038/nature14604] for different types of random networks and real-world network instances. The BPD-guided attack scheme often induces an abrupt collapse of the whole network, which may make it very difficult to defend.

  13. Prevention of Buffer overflow Attack Blocker Using IDS

    Directory of Open Access Journals (Sweden)

    Pankaj B. Pawar

    2012-10-01

    Full Text Available Now a day internet threat takes a blended attack form, targetingindividual users to gain control over networks and data. BufferOverflow which is one of the most occurring securityvulnerabilities in a Computer’s world. Buffer Overflow occurswhile writing data to a buffer and it overruns the buffer'sboundary and overwrites it to a adjacent memory. The techniquesto exploit buffer overflow vulnerability vary per architecture,Operating system and memory region. There are variousexploitation which causes to buffer overflow attack as stackbased exploitation, heap based exploitation and choice ofprogramming language and many more. Which may result inerratic program behavior, including memory access errors,incorrect results, a crash or a breach of system security. C andC++ are the two programming languages which do not check thatdata has overwritten to an array that results to an buffer overflow.There are many more techniques which has been used forprotecting the Computer from buffer overflow attack We areproposing a novel techniques for preventing data loss duringthe transmission of images of different formats. In this paper wehave discuss and compare certain tools and techniques whichprevent buffer overflows. We have also discuss some moderntools and techniques with their pros and cons.

  14. Compression failure of angle-ply laminates

    OpenAIRE

    Peel, Larry D

    1991-01-01

    The present work deals with modes and mechanisms of failure in compression of angleply laminates. Experimental results were obtained from 42 angle-ply IM7/8551-7a specimens with a lay-up of [ (±9) / (=F9)] 6s where 9, the off-axis angle, ranged from 0° to 90°. The results showed four failure modes, these modes being a function of off-axis angle. Failure modes include fiber compression, inplane transverse tension, inplane shear, and inplane transverse compression. Excessive inte...

  15. A taxonomy and discussion of software attack technologies

    Science.gov (United States)

    Banks, Sheila B.; Stytz, Martin R.

    2005-03-01

    Software is a complex thing. It is not an engineering artifact that springs forth from a design by simply following software coding rules; creativity and the human element are at the heart of the process. Software development is part science, part art, and part craft. Design, architecture, and coding are equally important activities and in each of these activities, errors may be introduced that lead to security vulnerabilities. Therefore, inevitably, errors enter into the code. Some of these errors are discovered during testing; however, some are not. The best way to find security errors, whether they are introduced as part of the architecture development effort or coding effort, is to automate the security testing process to the maximum extent possible and add this class of tools to the tools available, which aids in the compilation process, testing, test analysis, and software distribution. Recent technological advances, improvements in computer-generated forces (CGFs), and results in research in information assurance and software protection indicate that we can build a semi-intelligent software security testing tool. However, before we can undertake the security testing automation effort, we must understand the scope of the required testing, the security failures that need to be uncovered during testing, and the characteristics of the failures. Therefore, we undertook the research reported in the paper, which is the development of a taxonomy and a discussion of software attacks generated from the point of view of the security tester with the goal of using the taxonomy to guide the development of the knowledge base for the automated security testing tool. The representation for attacks and threat cases yielded by this research captures the strategies, tactics, and other considerations that come into play during the planning and execution of attacks upon application software. The paper is organized as follows. Section one contains an introduction to our research

  16. Nonadiabatic Hannay's Angle of Spin One Half in Grassmannian Version and Invariant Angle Coherent States

    OpenAIRE

    Cherbal, Omar; Maamache, Mustapha; Drir, Mahrez

    2003-01-01

    We propose to determinate the nonadiabatic Hannay’s angle of spin one half in a varying external magnetic field, by using an averaged version of the variational principal. We also show how the evolution and this nonadiabatic Hannay’s angle is associated with the evolution of Grassmannian invariant-angle coherent states.

  17. The accountability problem of flooding attacks in service-oriented architectures

    DEFF Research Database (Denmark)

    Jensen, Meiko; Schwenk, Jörg

    2009-01-01

    The threat of Denial of Service attacks poses a serious problem to the security of network-based services in general. For flooding attacks against service-oriented applications, this threat is dramatically amplified with potentially much higher impact and very little effort on the attacker's side...... flooding attack model, we illustrate the problem's parameters, and we finally discuss some general solution approaches. © 2008 IEEE....

  18. Avoiding Prankster Attack in Case of Selfish Driver Using the Location Aware Fixed Nodes - A Review

    OpenAIRE

    Namrata Singh; Khushneet Kaur

    2014-01-01

    VANET Security is a popular research area and concerns with the automatically driven vehicles. VANETs are prone to number of security breaching methods. These security breaches can be categorized as Replay Attach, Denial of Service, Fabrication Attack, Prankster Attack, etc. These attacks can cause massive traffic congestion, accident or to hurt large number of people with terrorism activities. Prankster Attack is the one, which is launched by sending the false information to other vehicles, ...

  19. Analysis and visualization of large complex attack graphs for networks security

    Science.gov (United States)

    Chen, Hongda; Chen, Genshe; Blasch, Erik; Kruger, Martin; Sityar, Irma

    2007-04-01

    In this paper, we have proposed a comprehensive and innovative approach for analysis and visualization of large complex multi-step cyber attack graphs. As an automated tool for cyber attack detection, prediction, and visualization, the newly proposed method transforms large quantities of network security data into real-time actionable intelligence, which can be used to (1) provide guidance on network hardening to prevent attacks, (2) perform real-time attack event correlation during active attacks, and (3) formulate post-attack responses. We show that it is possible to visualize the complex graphs, including all possible network attack paths while still keeping complexity manageable. The proposed analysis and visualization tool provides an efficient and effective solution for predicting potential attacks upon observed intrusion evidence, as well as interactive multi-resolution views such that an analyst can first obtain high-level overviews quickly, and then drill down to specific details.

  20. A Case of Brucellosis with Recurrent Attacks of Vasculitis

    Science.gov (United States)

    Korkmaz, Pınar; Kıdır, Mehtap; Namdar, Nazlı Dizen; Özmen, Ahmet; Uyar, Cemile; Değer, Ayşe Nur

    2016-01-01

    Brucellosis is a zoonosis that affects several organs or systems. Skin involvement is nonspecific and it is reported to range between 0,4 and 17% of the patients with brucellosis. Here, we defined a 36-year-old female patient presented to our clinic with a clinical picture of recurrent attacks of vasculitis due to brucellosis for the first time. Skin involvement and vasculitic lesions as a finding of skin involvement are nonspecific in brucellosis. Therefore, in the regions like Turkey where brucellosis is endemic, brucellosis should be kept in mind necessarily in the differential diagnosis of vasculitis. PMID:27042369

  1. Oxydizing attack process of an uranium ore by a carbonated liquor

    International Nuclear Information System (INIS)

    Continuous process of oxydizing attack of an uranium ore with a recycled aqueous solution of alkaline carbonates and bicarbonates containing uranium compounds at a concentration near the solubility limit at the attack temperature and recovery of the precipitated uranium in the solid phase remaining after the attack

  2. EMERGENCE ANGLE OF FLOW OVER AN AERATOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aerator is an important device for release works of hydraulic structures with high-speed flow in order to protect them from cavitation damage. This kind of protecting effect is related closely to cavity length below the aerator, while the cavity length is dominated by the emergence angle over the aerator. Therefore it is crucial to determine this angle accurately. In the present paper the affecting intensities of flow depth and the fluctuating velocity on this angle were analyzed through two introduced parameters. Furthermore, the improved expressions of emergence angle estimation, for both ramp-type and step-type aerators, were presented by means of 68 sets of experimental data from 6 projects based on error theory. The results showed that the present method has higher accuracy than the previously reported methods.

  3. Effective Authentication Technique for Distributed Denial of Service Attacks in Wireless Local Area Networks

    OpenAIRE

    S. Sathiyabama; M. Moorthy

    2012-01-01

    Problem statement: In 802.11-based Wireless LAN (WLAN), there is an mproved risk of security attacks. To defeat concealed attacks, there is a necessity to authenticate both access points and wireless stations. Approach: We propose a defensive technique for DDoS attack in WLAN. This authentication technique includes an Authentication Server (AS) in addition to the Wireless Station (WS) and Access Point (AP). Results: The authentication server holds both normal and attacker databases. The attac...

  4. Robustness of two-way quantum communication protocols against Trojan horse attack

    CERN Document Server

    Deng, F G; Li, X H; Zhou, H Y; Zhou, P

    2005-01-01

    We discuss the robustness of two-way quantum communication protocols against Trojan horse attack and introduce a novel attack, delay-photon Trojan horse attack. Moreover, we present a practical way for two-way quantum communication protocols to prevent the eavesdropper from stealing the information transmitted with Trojan horse attacks. It means that two-way quantum communication protocols is also secure in a practical application.

  5. Principles of Neural Network Artificial Immune System Design to Detect Attacks on Computers

    OpenAIRE

    Golovko, Vladimir; Myroslav, Komar; Sachenko, Anatoly

    2010-01-01

    It’s proposed to use artificial immune systems and neural networks to detect attacks on computer systems. The principles of attack detection system design based on artificial immune network are described, and the architecture of attack detection system is presented.

  6. Viewing angle analysis of integral imaging

    Science.gov (United States)

    Wang, Hong-Xia; Wu, Chun-Hong; Yang, Yang; Zhang, Lan

    2007-12-01

    Integral imaging (II) is a technique capable of displaying 3D images with continuous parallax in full natural color. It is becoming the most perspective technique in developing next generation three-dimensional TV (3DTV) and visualization field due to its outstanding advantages. However, most of conventional integral images are restricted by its narrow viewing angle. One reason is that the range in which a reconstructed integral image can be displayed with consistent parallax is limited. The other is that the aperture of system is finite. By far many methods , an integral imaging method to enhance the viewing angle of integral images has been proposed. Nevertheless, except Ren's MVW (Maximum Viewing Width) most of these methods involve complex hardware and modifications of optical system, which usually bring other disadvantages and make operation more difficult. At the same time the cost of these systems should be higher. In order to simplify optical systems, this paper systematically analyzes the viewing angle of traditional integral images instead of modified ones. Simultaneously for the sake of cost the research was based on computer generated integral images (CGII). With the analysis result we can know clearly how the viewing angle can be enhanced and how the image overlap or image flipping can be avoided. The result also promotes the development of optical instruments. Based on theoretical analysis, preliminary calculation was done to demonstrate how the other viewing properties which are closely related with the viewing angle, such as viewing distance, viewing zone, lens pitch, and etc. affect the viewing angle.

  7. Symptom Induction and De-escalation in the Treatment of Panic Attacks.

    Science.gov (United States)

    Dattilio, Frank M.

    1990-01-01

    Describes technique known as symptom induction and de-escalation for panic attacks in which goal is to reproduce the type of situation that may precipitate an attack and then to show the client how the attacks can be "turned on" as well as "turned off." (ABL)

  8. Examples of the Generalized Quantum Permanent Compromise Attack to the Blum-Micali Construction

    CERN Document Server

    Guedes, Elloá B; Lula, Bernardo

    2010-01-01

    This paper presents examples of the quantum permanent compromise attack to the Blum-Micali construction. Such attacks illustrate how a previous attack to the Blum-Micali generator can be extended to the whole Blum-Micali construction, including the Blum-Blum-Shub and Kaliski generators.

  9. On the security of Y-00 under fast correlation and other attacks on the key

    International Nuclear Information System (INIS)

    The security of the Y-00 direct encryption protocol under correlation attack is addressed. A Y-00 configuration that is more secure than AES under known-plaintext attack is presented. It is shown that under any ciphertext-only attack, full information-theoretic security on the Y-00 seed key is obtained for any encryption box ENC with proper deliberate signal randomization

  10. The mechanism of erosion of metallic materials under cavitation attack

    Science.gov (United States)

    Rao, B. C. S.; Buckley, D. H.

    1985-01-01

    The mean depth of penetration rates (MDPRs) of eight polycrystalline metallic materials, Al 6061-T6, Cu, brass, phosphor bronze, Ni, Fe, Mo, and Ti-5Al-2.5Sn exposed to cavitation attack in a viscous mineral oil with a 20 kHz ultrasonic oscillator vibrating at 50 micron amplitude are reported. The titanium alloy followed by molybdenum have large incubation periods and small MDPRs. The incubation periods correlate linearly with the inverse of hardness and the average MDPRs correlate linearly with the inverse of tensile strength of materials. The linear relationships yield better statistical parameters than geometric and exponential relationships. The surface roughness and the ratio of pit depth to pit width (h/a) increase with the duration of cavitation attack. The ratio h/a varies from 0.1 to 0.8 for different materials. Recent investigations (20) using scanning electron microscopy to study deformation and pit formation features are briefly reviewed. Investigations with single crystals indicate that the geometry of pits and erosion are dependent on their orientation.

  11. Factors affecting attack rate of whitefly on the eggplant

    Directory of Open Access Journals (Sweden)

    Leite Germano Leão Demolin

    2003-01-01

    Full Text Available The objective of this study was to determine the effects of weather, predators and parasitoids, canopy height and plant age, leaf chemical composition, levels of leaf N and K and leaf trichomes on the intensity of Bemisia tabaci attack on Solanum melongena. A higher density of nymph and whitefly adults was recorded at the base and medium of the plant compared to the apex. A higher number of eggs was observed on the medium part than on the apical and base part of the plants dossel. An increase in the density of whitefly is associated with an increase in temperature.

  12. Risk factors of transient ischemic attack: An overview

    Directory of Open Access Journals (Sweden)

    Supreet Khare

    2016-01-01

    Full Text Available Transient ischemic attack (TIA is a transient episode of neurologic dysfunction caused due to loss of blood flow to the brain or spinal cord without acute infarction. Depending on the area of the brain involved, symptoms of TIA vary widely from patient to patient. Since the blockage period in TIA is very short-lived, there is no permanent damage. Risk factors for TIA include family history of stroke or TIA, age above 55 years or older, higher risk of TIA in males than females, high blood pressure, diabetes mellitus, and tobacco smoking. Genetics, race, and imbalance in lipid profile are other risk factors of TIA. TIA is usually diagnosed after taking a thorough history and a physical examination. Several radiological tests such as computed tomography and magnetic resonance imaging are useful in the evaluation of patients who have had a TIA. Ultrasound of the neck and an echocardiogram of the heart are other tests useful in the diagnosis and evaluation of the attack. The treatment following acute recovery from a TIA depends on the underlying cause. Patients who have more than 70% stenosis of the carotid artery, removal of atherosclerotic plaque is usually done by carotid endarterectomy surgery. One-third of the people with TIA can later have recurrent TIAs and one-third can have a stroke because of permanent nerve cell loss. Having a TIA is a risk factor for eventually having a stroke. Educating the patients and inculcating lifestyle modifications in them are initial steps to minimize the prevalence of transient ischemic attack.

  13. A video-polygraphic analysis of the cataplectic attack

    DEFF Research Database (Denmark)

    Rubboli, G; d'Orsi, G; Zaniboni, A;

    2000-01-01

    arrest of eye movements and phasic, massive, inhibitory muscular events; falling phase, characterized by a rhythmic pattern of suppressions and enhancements of muscular activity, leading to the fall; atonic phase, characterized by complete muscle atonia. Six episodes out of 11 were associated with...... bradycardia, that was maximal during the atonic phase. CONCLUSIONS: Analysis of the muscular phenomena that characterize cataplectic attacks in a standing patient suggests that the cataplectic fall occurs with a pattern that might result from the interaction between neuronal networks mediating muscular atonia...... of REM sleep and neural structures subserving postural control....

  14. Nonlinear analysis of NPP safety against the aircraft attack

    Science.gov (United States)

    Králik, Juraj; Králik, Juraj

    2016-06-01

    The paper presents the nonlinear probabilistic analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The dynamic load is defined in time on base of the airplane impact simulations considering the real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

  15. The resilience of interdependent transportation networks under targeted attack

    CERN Document Server

    Zhang, Peng; Zhao, Zhuang; Li, Daqing; Lu, Guangquan; Wang, Yunpeng; Xiao, Jinghua

    2013-01-01

    Modern world builds on the resilience of interdependent infrastructures characterized as complex networks. Recently, a framework for analysis of interdependent networks has been developed to explain the mechanism of resilience in interdependent networks. Here we extend this interdependent network model by considering flows in the networks and study the system's resilience under different attack strategies. In our model, nodes may fail due to either overload or loss of interdependency. Under the interaction between these two failure mechanisms, it is shown that interdependent scale-free networks show extreme vulnerability. The resilience of interdependent SF networks is found in our simulation much smaller than single SF network or interdependent SF networks without flows.

  16. A 3-Subset Meet-in-the-Middle Attack: Cryptanalysis of the Lightweight Block Cipher KTANTAN

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Rechberger, Christian

    2011-01-01

    In this paper we describe a variant of existing meet-in-the-middle attacks on block ciphers. As an application, we propose meet-in-the-middle attacks that are applicable to the KTANTAN family of block ciphers accepting a key of 80 bits. The attacks are due to sonic weaknesses in its bitwise key s...... low data requirements, these attacks are valid even in RFID-like environments where only a very limited amount of text material may be available to an attacker....

  17. WLAN Security-Active Attack of WLAN Secure Network

    Directory of Open Access Journals (Sweden)

    Anil Kumar Singh

    2011-05-01

    Full Text Available In Wireless Local Area Network data transfer from one node to another node via air in the form of radio waves. There is no physical medium for transferring the data like traditional LAN. Because of its susceptible nature WLAN can open the door for the intruders and attackers that can come from any direction. Security is the most important element in WLAN. MAC address filtering is one of the security methods for securing the WLAN. But it is also vulnerable. In this paper we will demonstrate how hackers exploit the WLAN vulnerability (Identity theft of legitimate user to access the Wireless Local Area Network.

  18. Mathematical Attacks on RSA Cryptosystem

    Directory of Open Access Journals (Sweden)

    Imad K. Salah

    2006-01-01

    Full Text Available In this paper some of the most common attacks against Rivest, Shamir, and Adleman (RSA cryptosystem are presented. We describe the integer factoring attacks, attacks on the underlying mathematical function, as well as attacks that exploit details in implementations of the algorithm. Algorithms for each type of attacks are developed and analyzed by their complexity, memory requirements and area of usage.

  19. Cultural Memory of Sorrow in Advertising after the Terrorist Attacks

    OpenAIRE

    Esther Martínez Pastor; Clara Simón

    2015-01-01

    The general objective of this research study is to do a comparative research to investigate the perception of sorrow in the advertising in the press after the terrorist attacks: 11/09/2001 (U.S.) and 11/04/2004 (Spain). The general hypothesis considers that there are similar perceptions of the sorrow towards the ads although there are cultural differences. On a computer program the subject was shown these images about announcement advertisement published in the press after the 09/11 and 11/04...

  20. Cultural Memory of Sorrow in Advertising after the Terrorist Attacks

    Directory of Open Access Journals (Sweden)

    Esther Martínez Pastor

    2015-09-01

    Full Text Available The general objective of this research study is to do a comparative research to investigate the perception of sorrow in the advertising in the press after the terrorist attacks: 11/09/2001 (U.S. and 11/04/2004 (Spain. The general hypothesis considers that there are similar perceptions of the sorrow towards the ads although there are cultural differences. On a computer program the subject was shown these images about announcement advertisement published in the press after the 09/11 and 11/04 in a random order and was asked different questions that explored their perception and attitudes with regard to these advertisements

  1. WLAN Security-Active Attack of WLAN Secure Network

    OpenAIRE

    Anil Kumar Singh; Bharat Mishra

    2011-01-01

    In Wireless Local Area Network data transfer from one node to another node via air in the form of radio waves. There is no physical medium for transferring the data like traditional LAN. Because of its susceptible nature WLAN can open the door for the intruders and attackers that can come from any direction. Security is the most important element in WLAN. MAC address filtering is one of the security methods for securing the WLAN. But it is also vulnerable. In this paper we will demonstrate ho...

  2. Design and Analysis of an Attack Resilient and Adaptive Medium access Control Protocol for Computer Networks

    CERN Document Server

    Shukla, Piyush Kumar; Bhadoria, Dr Sarita Singh

    2009-01-01

    The challenge of designing an efficient Medium Access Control (MAC) protocol and analyzing it has been an important research topic for over 30 years. This paper focuses on the performance analysis (through simulation) and modification of a well known MAC protocol CSMA/CD. The existing protocol does not consider the wastage of bandwidth due to unutilized periods of the channel. By considering this fact, performance of MAC protocol can be enhanced. The purpose of this work is to modify the existing protocol by enabling it to adapt according to state of the network. The modified protocol takes appropriate action whenever unutilized periods detected. In this way, to increase the effective bandwidth utilization and determine how it behaves under increasing load, and varying packet sizes. It will also include effects of attacks i.e. Denial of service attacks, Replay Attack, Continuous Channel Access or Exhaustion attack, Flooding attack, Jamming (Radio interference) attack, Selective forwarding attack which degrade...

  3. Simulating effectiveness of helicopter evasive manoeuvres to RPG attack

    Science.gov (United States)

    Anderson, D.; Thomson, D. G.

    2010-04-01

    The survivability of helicopters under attack by ground troops using rocket propelled grenades has been amply illustrated over the past decade. Given that an RPG is unguided and it is infeasible to cover helicopters in thick armour, existing optical countermeasures are ineffective - the solution is to compute an evasive manoeuvre. In this paper, an RPG/helicopter engagement model is presented. Manoeuvre profiles are defined in the missile approach warning sensor camera image plane using a local maximum acceleration vector. Required control inputs are then computed using inverse simulation techniques. Assessments of platform survivability to several engagement scenarios are presented.

  4. Analysis of ettringite attack to stabilized railway bases and embankments

    OpenAIRE

    Ramon Tarragona, Anna; Alonso Pérez de Agreda, Eduardo

    2013-01-01

    Two cases of massive sulphate attack to cement treated embankments and track bases in a high speed railway line are described. In the first case, two large access embankments to a railway viaduct were treated with jet–grouting columns. In the second case a compacted cement treated soil was placed over a rigid concrete caisson. The treated layer, 1.5 m thick, expanded at a continuous rate of 0.9-1.3 mm/month. In the two cases the soil was excavated from nearby cuts in gypsiferous Tertiary (...

  5. Attack Coverage in High-Level Men's Volleyball: Organization on the Edge of Chaos?

    Science.gov (United States)

    Laporta, Lorenzo; Nikolaidis, Pantelis; Thomas, Luke; Afonso, José

    2015-09-29

    Change is pervasive, but emerging patterns are occasionally detectable through analysis of systemic behaviors. Match analysis uses these patterns in order to reduce the degree of improvisation and to optimize the training process. However, it is possible that certain game phases elude systematic patterning. In this vein, our aim was to analyze the case of attack coverage in men's volleyball, as we suspected it would elude systematic patterning and has received negligible attention in scientific research. We analyzed the occurrence of attack coverage in 4544 plays of the 2011 Volleyball World League. A Chi-square test with residual adjusted values was applied to explore significant associations between variables. A Monte Carlo correction was applied, as some cells had n<5. Effect sizes were determined using Cramer's V. Overall, attack coverage occurred in 3.89% of ball possessions, and 23 distinct structures emerged. These structures lacked significant associations with the game complex, setting zone, and effect of attack coverage. Conversely, attack coverage structures showed significant associations with the attack zone and tempo, with very strong effect sizes (V=0.472 and V=0.521, respectively). As certain attack zones are deeply associated with attack tempo, it is apparent that quicker attack plays affect attack coverage structuring, promoting the formation of less complex structures. Ultimately, attack coverage structures seem to depend on momentary constraints, thereby rendering rigid systematization impracticable. Still, we contended that a principle-based approach might be suitable. This invites researchers to rethink how to interpret game regularities. PMID:26557208

  6. Influence of attacker's target recognition ability on defense strategy in homogeneous parallel systems

    International Nuclear Information System (INIS)

    The article considers defense resource allocation in a system exposed to external intentional attack. The defender distributes its resource between deploying redundant elements and their protection from attacks. The attacker observes all the elements and tries to detect the unprotected elements. All the detected unprotected elements are destroyed with negligible effort. The attacker then distributes its effort evenly among all of the undetected elements or among elements from a chosen subset of undetected elements. The vulnerability of each element is determined by an attacker-defender contest success function depending on the resources allocated to protection and attack efforts and on the contest intensity. The expected damage caused by the attack is evaluated as system unsupplied demand. The article studies the influence of the unprotected elements' detection probability on the optimal resource distribution.

  7. Radon - an angle of view

    International Nuclear Information System (INIS)

    Apart from its radiation effects on living organism, radon induces the formation of atmospheric ions which are beneficial to man: some asthmatics can breathe more easily in an environment with elevated ion levels, the blood pH increases, the fraction of albumins is higher while the serotonin level is lower, sedimentation decreases and the leukocyte counts in peripherals diminish. The blood pressure, particularly in people suffering from hypertension, drops appreciably. The production of pituitary hormones as well as the overall sexual activity is stimulated by ions in air. Exposure to negative ions affects circulation through the skin, reduces skin temperature and improves overall resistance of the organism to infection. Negative ions also have a stimulating effect on mental activity and help against insomnia. Sites where radon is present in not too high concentrations are often famous as climatic spas. So, antiradon provisions, if exercised too thoroughly, may have adverse rather than positive consequences. All pros and cons should always be taken into account when deciding on antiradon steps. (P.A.)

  8. Precision measurements of the CKM angle gamma

    CERN Document Server

    CERN. Geneva

    2016-01-01

    The level of CP-violation permitted within the Standard Model cannot account for the matter dominated universe in which we live. Within the Standard Model the CKM matrix, which describes the quark couplings, is expected to be unitary. By making precise measurements of the CKM matrix parameters new physics models can be constrained, or with sufficient precision the effects of physics beyond the standard model might become apparent. The CKM angle gamma is the least well known angle of the unitarity triangle. It is the only angle easily accessible at tree-level, and furthermore has almost no theoretical uncertainties. Therefore it provides an invaluable Standard Model benchmark against which other new physics sensitive tests of the CP-violation can be made. I will discuss recent measurements of gamma using the the Run 1 LHCb dataset, which improve our knowledge of this key parameter.

  9. Pericarditis - after heart attack

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000166.htm Pericarditis - after heart attack To use the sharing features on this page, ... occur in the days or weeks following a heart attack. Causes Two types of pericarditis can occur after ...

  10. Angle-Resolved Spectroscopy of Parametric Fluorescence

    CERN Document Server

    Hsu, Feng-kuo

    2013-01-01

    The parametric fluorescence from a nonlinear crystal forms a conical radiation pattern. We measure the angular and spectral distributions of parametric fluorescence in a beta-barium borate crystal pumped by a 405-nm diode laser employing angle-resolved imaging spectroscopy. The experimental angle-resolved spectra and the generation efficiency of parametric down conversion are compared with a plane-wave theoretical analysis. The parametric fluorescence is used as a broadband light source for the calibration of the instrument spectral response function in the wavelength range from 450 to 1000 nm.

  11. Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects

    Science.gov (United States)

    Jiang, Yuzhen; Chang, Dolly S.; Zhu, Haogang; Khawaja, Anthony P.; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M.

    2015-01-01

    Objective To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Design Longitudinal cohort study. Participants Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Methods Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Main Outcome Measures Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. Results No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1

  12. On Dihedral Angles of a Simplex

    OpenAIRE

    Maehara, H.

    2013-01-01

    For an $n$-simplex, let $\\alpha,\\,\\beta$ denote the maximum, and the minimum dihedral angles of the simplex, respectively. It is proved that the inequality $\\alpha\\le \\arccos(1/n)\\le \\beta$ always holds, and either side equality implies that the $n$-simplex is a regular simplex. Similar inequalities are also given for a star-simplex, which is defined as a simplex that has a vertex (apex) such that the angles between distinct edges incident to the apex are all equal. Further, an explicit formu...

  13. Practising of radiological emergency caused by a terrorist attack

    International Nuclear Information System (INIS)

    After the events of September 11, 2001 terrorist working has become an important factor in the forecasts to adopt in the face of the possibility of confronting different radiological emergencies. The not wanted events of exposure to ionizing radiations can take place by flaws of systems or accidents, or also by criminal voluntary actions. These malevolent actions can include attacks or sabotages in nuclear plants, detonation of manufactured nuclear devices or acquired under ground, robbery of radioactive sources to manufacture the calls dirty bombs or to cause damage, panic or threats. In the scenarios in that the radiological emergency is voluntarily provoked the moment and place of the attack are chosen by the aggressors, therefore the ionizing radiations will be in not prepared atmospheres neither equipped to the effect. This increases the confusion, the panic and the damage not only caused by the radiation effects but also by the uncertainty and consequent reactions. To diminish the effects of this type of threats it is necessary to make forecasts and to train the personnel that it can be direct or indirectly involved. During 2005, an exercise in which it was outlined the robbery by part of a group command of a source of Co 60 of 5000 Ci that it was transported to make a decanting in a medical center of The Pampa county, Argentina. It was about a cabinet exercise, planned and executed jointly among the Nuclear Regulatory Authority and the Secretary of Interior Safety, in which participated the professionals of the nuclear area that by law are the responsible ones of coordinating the actions in the event of an emergency of this type, and the safety forces that depend of the Secretary of Interior Safety, Federal and Provincial Policemen, Naval Prefecture and National Gendarmerie. The exercise last one day during which 9 main situations were approached that were unchained after having produced the attack and initial robbery. For each situation it was checked the

  14. Multi-Level Parsing Based Approach Against Phishing Attacks With the Help of Knowledge Bases

    Directory of Open Access Journals (Sweden)

    Gaurav Kumar Tak

    2013-11-01

    Full Text Available The increasing use of internet all over the world,be it in households or in corporate firms, has ledto anunprecedented rise in cyber-crimes. Amongst these the major chunk consists of Internet attacks which arethe most popular and common attacks are carried over the internet. Generally phishing attacks, SSLattacks and some other hacking attacks are kept into this category. Security against these attacks isthemajor issue of internet security in today’s scenario where internet has very deep penetration. Internet hasno doubt made our lives very convenient. It has provided many facilities to us at penny’s cost. For instanceit has made communication lightning fast and that too at a very cheap cost. But internet can pose addedthreats for those users who are not well versed inthe ways of internet and unaware of the security risksattached with it. Phishing Attacks, Nigerian Scam,Spam attacks, SSL attacks and other hacking attacksaresome of the most common and recent attacks to compromise the privacy of the internet users. Many a timesif the user isn’t careful, then these attacks are able to steal the confidential information of user (orunauthorized access. Generally these attacks are carried out with the help of social networking sites,popular mail server sites, online chatting sites etc. Nowadays, Facebook.com, gmail.com, orkut.com andmany other social networking sites are facing thesesecurity attack problems.This paper discusses a Knowledge Base Compound approach which is based on query operations andparsing techniques to counter these internet attacks using the web browser itself. In this approach wepropose to analyze the web URLs before visiting theactual site, so as to provide security against webattacks mentioned above. This approach employs various parsing operations and query processing whichuse many techniques to detect the phishing attacksas well as other web attacks. The aforementionedapproach is completely based on operation through the

  15. A Lanchester model of submarine attack on a carrier battlegroup

    OpenAIRE

    Eagle, James N.

    1987-01-01

    A Lanchester model is developed for a battlegroup ASW engagement. Two variations are included. In the first, long-range missile firing submarines, short-range missile or torpedo firing submarines, and submarines firing only torpedoes distribute their attack uniformly over battlegroup escort ships and carriers. In the second variation, the attack is concentrated on the carriers.

  16. Elimination of a Second-Law-Attack, and All Cable-Resistance-Based Attacks, in the Kirchhoff-Law-Johnson-Noise (KLJN Secure Key Exchange System

    Directory of Open Access Journals (Sweden)

    Laszlo B. Kish

    2014-10-01

    Full Text Available We introduce the so far most efficient attack against the Kirchhoff-law-Johnson-noise (KLJN secure key exchange system. This attack utilizes the lack of exact thermal equilibrium in practical applications and is based on cable resistance losses and the fact that the Second Law of Thermodynamics cannot provide full security when such losses are present. The new attack does not challenge the unconditional security of the KLJN scheme, but it puts more stringent demands on the security/privacy enhancing protocol than for any earlier attack. In this paper we present a simple defense protocol to fully eliminate this new attack by increasing the noise-temperature at the side of the smaller resistance value over the noise-temperature at the side with the greater resistance. It is shown that this simple protocol totally removes Eve’s information not only for the new attack but also for the old Bergou-Scheuer-Yariv attack. The presently most efficient attacks against the KLJN scheme are thereby completely nullified.

  17. Strategies of detecting Profile-injection attacks in E-Commerce Recommender System: A survey Partha

    Directory of Open Access Journals (Sweden)

    Sarathi Chakraborty,

    2015-12-01

    Full Text Available E-commerce recommender systems are vulnerable to different types of shilling attack where the attacker influences the recommendation procedure in favor of him by inserting fake user-profiles into the system. From one point of view, the attacks can be of type push or nuke-either to promote or to demote a product. On the other hand, attacks can be classified as high-knowledge or low-knowledge attack depending on the amount of system knowledge required for making the attack successful. Several research works have been done in the last two decades for defending attacks on recommender systems. In this paper, we have surveyed the major works done in this area by different researchers. After a brief explanation of different attack types and attack models, we discussed the attack detection strategies proposed by the researchers mainly under five categories- Generic and model specific attribute based, rating distribution based, outlier analysis based, statistical approach based and clustering based.

  18. Preliminary report of a community survey of panic attacks and panic disorder.

    OpenAIRE

    Stirton, R F; Brandon, S

    1988-01-01

    This study looked at the prevalence of panic attacks and panic disorder in a British population. Three thousand people (aged 18-65) registered with a Leicester general practice were sent a postal questionnaire which screened for panic attacks. Where appropriate this was followed by a diagnostic interview. Preliminary results are reported for the first 1500 subjects sampled. Panic attacks are a common experience in the study population (7.5% of responders experienced them around the time of th...

  19. Importance of Video-EEG Monitoring in the Diagnosis of Refractory Panic Attacks

    Directory of Open Access Journals (Sweden)

    Batool F. Kirmani

    2013-01-01

    Full Text Available Partial seizures can be misdiagnosed as panic attacks. There is considerable overlap of symptoms between temporal lobe seizures and panic attacks making the diagnosis extremely challenging. Temporal lobe seizures can present with intense fear and autonomic symptoms which are also seen in panic disorders. This results in delay in diagnosis and management. We report an interesting case of a young woman who was diagnosed with right temporal lobe seizures with symptoms suggestive of a panic attack.

  20. Importance of Video-EEG Monitoring in the Diagnosis of Refractory Panic Attacks

    OpenAIRE

    Kirmani, Batool F.; Diana Mungall

    2013-01-01

    Partial seizures can be misdiagnosed as panic attacks. There is considerable overlap of symptoms between temporal lobe seizures and panic attacks making the diagnosis extremely challenging. Temporal lobe seizures can present with intense fear and autonomic symptoms which are also seen in panic disorders. This results in delay in diagnosis and management. We report an interesting case of a young woman who was diagnosed with right temporal lobe seizures with symptoms suggestive of a panic attack.

  1. A strategic analysis of the origins of international terrorist attacks on aviation and the British responses

    OpenAIRE

    Malik, Omar

    1997-01-01

    This research examines the effects on Great Britain of international terrorist attacks on aviation. The methodology is utilitarian. It is also eclectic, drawing upon scholarly and operational sources. The first objective was factual: to establish the origins of international attacks on aviation, their effects on Great Britain, and the British responses. It found that the attacks were a "blocked tactic!' product of the Palestine conflict. They had neither political nor economic ...

  2. Status of the CDF small angle spectrometer

    International Nuclear Information System (INIS)

    During the 1987 Tevatron collider period the CDF small angle spectrometer system was partially installed and elastic scattering events were recorded in a special high-β run. The design and physics goals of this system are described and results from an analysis of the elastic scattering data are discussed

  3. Performance analysis of Jakimoski-Kocarev attack on a class of chaotic cryptosystems

    OpenAIRE

    Li, SJ; Mou, XQ; Ji, Z.; Zhang, JH; Cai, YL

    2003-01-01

    Recently Jakimoski and Kocarev cryptanalyzed two chaotic cryptosystems without using chaotic synchronization—Baptista cryptosystem and Alvarez cryptosystem. As a result, they pointed out that neither of the two cryptosystems are secure to known-plaintext attacks. In this Letter, we re-study the performance of Jakimoski–Kocarev attack on Baptista cryptosystem and find that it is not efficient enough as a practical attack tool. Furthermore, a simple but effective remedy is presented to resist J...

  4. AN ANALYSIS OF CURRENT COMPUTER NETWORK ATTACK PROCEDURES, THEIR MITIGATION MEASURES AND THE DEVELOPMENT OF AN IMPROVED DENIAL OF SERVICE (DoS ATTACK MODEL

    Directory of Open Access Journals (Sweden)

    IHEKWEABA OGECHI

    2013-04-01

    Full Text Available This paper presents the major network attack profiles, taxonomies, classification and identification frameworks. Further, current approaches for intrusion detection on networks were x-rayed though, with emphasis on Denial of Service (DoS attacks only. The concept of intelligent agents and subsequently adaptive systems was elucidated, the properties derived were used as a proof of concept, and then applied in the development of a model for an adaptive intelligent multi-agent for network protection, against denial of service attacks.

  5. Experimental technique of small angle neutron scattering

    International Nuclear Information System (INIS)

    The main parts of Small Angle Neutron Scattering (SANS) spectrometer, and their function and different parameters are introduced from experimental aspect. Detailed information is also introduced for SANS spectrometer 'Membrana-2'. Based on practical experiments, the fundamental requirements and working condition for SANS experiments, including sample preparation, detector calibration, standard sample selection and data preliminary process are described. (authors)

  6. Detection and Modeling of Cyber Attacks with Petri Nets

    Directory of Open Access Journals (Sweden)

    Bartosz Jasiul

    2014-12-01

    Full Text Available The aim of this article is to present an approach to develop and verify a method of formal modeling of cyber threats directed at computer systems. Moreover, the goal is to prove that the method enables one to create models resembling the behavior of malware that support the detection process of selected cyber attacks and facilitate the application of countermeasures. The most common cyber threats targeting end users and terminals are caused by malicious software, called malware. The malware detection process can be performed either by matching their digital signatures or analyzing their behavioral models. As the obfuscation techniques make the malware almost undetectable, the classic signature-based anti-virus tools must be supported with behavioral analysis. The proposed approach to modeling of malware behavior is based on colored Petri nets. This article is addressed to cyber defense researchers, security architects and developers solving up-to-date problems regarding the detection and prevention of advanced persistent threats.

  7. Performance Analysis of AODV under Black Hole Attack through Use of OPNET Simulator

    CERN Document Server

    Esmaili, H A; gharaee, Hossein

    2011-01-01

    Mobile ad hoc networks (MANETs) are dynamic wireless networks without any infrastructure. These networks are weak against many types of attacks. One of these attacks is the black hole. In this attack, a malicious node advertises itself as having freshest or shortest path to specific node to absorb packets to itself. The effect of black hole attack on ad hoc network using AODV as a routing protocol will be examined in this research. Furthermore, we investigate solution for increasing security in these networks. Simulation results using OPNET simulator depict that packet delivery ratio in the presence of malicious nodes, reduces notably.

  8. On the Measurement of Privacy as an Attacker's Estimation Error

    CERN Document Server

    Rebollo-Monedero, David; Diaz, Claudia; Forné, Jordi

    2011-01-01

    A wide variety of privacy metrics have been proposed in the literature to evaluate the level of protection offered by privacy enhancing-technologies. Most of these metrics are specific to concrete systems and adversarial models, and are difficult to generalize or translate to other contexts. Furthermore, a better understanding of the relationships between the different privacy metrics is needed to enable more grounded and systematic approach to measuring privacy, as well as to assist systems designers in selecting the most appropriate metric for a given application. In this work we propose a theoretical framework for privacy-preserving systems, endowed with a general definition of privacy in terms of the estimation error incurred by an attacker who aims to disclose the private information that the system is designed to conceal. We show that our framework permits interpreting and comparing a number of well-known metrics under a common perspective. The arguments behind these interpretations are based on fundame...

  9. A Comparison of Link Layer Attacks on Wireless Sensor Networks

    CERN Document Server

    Mohammadi, Shahriar; 10.5121/jgraphhoc.2011.3103

    2011-01-01

    Wireless sensor networks (WSNs) have many potential applications [1, 5] and unique challenges. They usually consist of hundreds or thousands small sensor nodes such as MICA2, which operate autonomously; conditions such as cost, invisible deployment and many application domains, lead to small size and limited resources sensors [2]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional networks security techniques are unusable on WSNs [2]; due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. So, security is a vital requirement for these networks; but we have to design a proper security mechanism that attends to WSN's constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs' link layer a...

  10. The Oracle a New Intelligent Cooperative Strategy of Attacks on Trust and Reputation Systems

    Directory of Open Access Journals (Sweden)

    Janiszewski Marek

    2014-06-01

    Full Text Available The paper presents a new concept of attack on trust and reputation systems. The oracle attack could violate the security provided by some of the existing reputation systems. The formal model of the attack is presented in the article on the base of the reference trust model, provided by the author. The author has proved that this type of attack could be eficient. On the other hand, a sort of measures is provided in the paper which could be implemented in the reputation systems to overcome identified vulnerabilities, unfortunately at the cost of increase of system complication. The paper also provides a definition of intelligent strategies of attacks on trust and reputation systems based on cooperation of many malicious nodes and justifies why this type of attacks is a serious threat

  11. Attacks of Asthma due to Chlorinized Water: Case Report

    Directory of Open Access Journals (Sweden)

    Murat Eyup Berdan

    2008-02-01

    Full Text Available The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure to strong respiratory irritant with chlorinized water in two subjects with no past history of asthma or atopy. We conclude that airway hyperresponsiveness can develop or increase after chronic inhalation of high concentrations of irritants such as chlorinized water an indoor irritant factor and that these changes may be prolonged. [TAF Prev Med Bull. 2008; 7(1: 87-90

  12. Attacks of Asthma due to Chlorinized Water: Case Report

    Directory of Open Access Journals (Sweden)

    Murat Eyup Berdan

    2008-02-01

    Full Text Available The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure to strong respiratory irritant with chlorinized water in two subjects with no past history of asthma or atopy. We conclude that airway hyperresponsiveness can develop or increase after chronic inhalation of high concentrations of irritants such as chlorinized water an indoor irritant factor and that these changes may be prolonged. [TAF Prev Med Bull 2008; 7(1.000: 87-90

  13. Analysis, classification and detection methods of attacks via wireless sensor networks in SCADA systems

    OpenAIRE

    Botvinkin, Pavel Viktorovich; Kamaev, Valery Anatolevich; Nefedova, Irina Sergeevna; Finogeev, Aleksey Germanovich; Finogeev, Egor Alekseevich

    2014-01-01

    Effectiveness of information security of automated process control systems, as well as of SCADA, depends on data transmissions protection technologies applied on transport environments components. This article investigates the problem of detecting attacks on WSN (wireless sensor networks) of SCADA systems. As the result of analytical studies the authors developed the detailed classification of external attacks on sensor networks and brought the detailed description of attacking impacts on com...

  14. A fringe shadow method for measuring flapping angle and torsional angle of a dragonfly wing

    Science.gov (United States)

    Zeng, Lijiang; Matsumoto, Hirokazu; Kawachi, Keiji

    1996-05-01

    A fringe shadow (FS) method was developed for measuring the flapping angle and torsional angle of a dragonfly wing during beating motion. This new method involves two sets of fringe patterns projected onto the wing from orthogonal directions. The torsional angle is determined using the length of the shadow of the wing chord that is cast by the two sets of fringe patterns. The flapping angle is determined using the shadowgraph of the wing projected by a laser. The advantages of the FS method are its capability (i) to measure the flapping angle and torsional angle of a dragonfly wing simultaneously using only one high-speed camera and (ii) to recognize the spanwise position of a section from the number of fringes, without having to use diffuse marks that are common in current methods. The resolution of the FS method can be changed easily by adjusting the fringe spacing. The measurement results for the torsional angle and flapping angle of a dragonfly wing prove the effectiveness of the FS method in studying the flight performance of dragonflies.

  15. Impact of Rushing attack on Multicast in Mobile Ad Hoc Network

    CERN Document Server

    Palanisamy, V

    2009-01-01

    A mobile ad hoc network (MANETs) is a self-organizing system of mobile nodes that communicate with each other via wireless links with no fixed infrastructure or centralized administration such as base station or access points. Nodes in a MANETs operate both as host as well as routers to forward packets for each other in a multihop fashion. For many applications in wireless networks, multicasting is an important and frequent communication service. By multicasting, since a single message can be delivered to multiple receivers simultaneously. It greatly reduces the transmission cost when sending the same packet to multiple recipients. The security issue of MANETs in group communications is even more challenging because of involvement of multiple senders and multiple receivers. At that time of multicasting, mobile ad hoc network are unprotected by the attacks of malicious nodes because of vulnerabilities of routing protocols. Some of the attacks are Rushing attack, Blackhole attack, Sybil attack, Neighbor attack ...

  16. Leaf-cutting ant attack in initial pine plantations and growth of defoliated plants

    OpenAIRE

    Mariane Aparecida Nickele; Wilson Reis Filho; Edilson Batista Oliveira; Edson Tadeu Iede; Nádia Caldato; Priscila Strapasson

    2012-01-01

    The objective of this work was to evaluate the natural attack by Acromyrmex crassispinus in initial Pinus taeda plantations without control measures against ants, as well as the effect of defoliation in seedlings of P. taeda. Evaluations of the attack of leaf-cutting ants on P. taeda plantations were done monthly in the first six months, then 9 and 12 months after planting. The percentages of plants that were naturally attacked by ants were registered. The effect of defoliation was evaluated ...

  17. Evaluation of Seizure Attacks in Patients with Cerebrovascular Accident

    Directory of Open Access Journals (Sweden)

    Ebrahim Koochaki

    2013-04-01

    Full Text Available Background: The most common reason for seizure in elderly duration is the stroke. This study was conducted aiming to assess the frequency of seizure attack occurrence in those patients. Materials and Methods: This investigation was carried out through a cross-sectional method for one year on 330 patients admitted to the neurology ward as diagnosed with stroke. The required data was collected through the researcher-made questionnaire from the patients suffering from stoke which was diagnosed based on clinical findings, CT-Scan and MRI as required. Results: Among 330 patient suffering from stroke (162 men and 168 women, 48 cases (14.5% were suffering from seizure. Six percent of the patients had early seizure and another 8.5% had late seizure. Among 162 men suffering from the stroke, 32 ones were without seizures and 30 men were suffering the seizure. A number of 150 women out of total 168 ones suffering from the stroke, had no seizure and 18 others had seizures; frequency of seizure occurrence was more in male samples (p=0.044. In the people under 60 year, there were mostly early types of seizure (45% and in the age range above 60 year, it was mostly late type (89.3%. A 68.5% of the patients suffering from the seizure had experienced ischemic stroke. However, the frequency of seizure occurrence in the patients with hemorrhagic stroke was statistically greater (p=0.003. Conclusion: This examination showed that occurrence of seizure attacks in the people with stroke is 14.5% and it is seen more in the hemorrhagic strokes than ischemic ones. The frontoparietal area is the most common location involved and tonic clonic was the most common seizure in the patients suffering from it who have experienced the stroke

  18. Relation of EEG and computerized tomography in transient ischaemic attacks

    International Nuclear Information System (INIS)

    80 patients with transient ischaemic attack (TIA) were examined via computer tomogram (CT) and electronencephalogram (EEG). 53 patients were found to have a normal CT and 32 a normal EEG. In the patients with pathological CT findings (27) a significantly lower number of normal EEG's (22) was seen. Further subdivision of the 27 pathological CT findings revealed 12 patients with hypodense areas (infarctions) and 15 patients with an atrophy only. A normal EEG was significantly rarer in patients with a hypodense lesion (2) and in those with atrophy (3), focal EEG changes being significantly more frequent. Hence EEG findings facilitate the aetiological linking of an atrophy to an ischaemic stroke, especially when EEG follow-up examinations are included in the diagnostic procedure. (orig.)

  19. A Study and Detection of TCP SYN Flood Attacks with IP spoofing and its Mitigations

    Directory of Open Access Journals (Sweden)

    Deepak Singh Rana

    2012-07-01

    Full Text Available Flooding attacks are major threats on TCP/IP protocol suite these days; Maximum attacks are launched through TCP and exploit the resources and bandwidth of the machine. Flooding attacks are DDOS (Distributed denial of service attacks and utilize the weakness of the network protocols. SYN flood exploits the 3-way handshaking of the TCP by sending many SYN request with IP spoofing technique to victim host and exhaust the backlog queue resource of the TCP and deny legitimate user to connect. Capturing the packet flow is very important to detecting the DOS attack. This paper present how the TCP SYN flood takes place and show the number of packets received by the victim server under the attack.

  20. Low Serum Concentrations of Vitamin B6 and Iron Are Related to Panic Attack and Hyperventilation Attack

    Directory of Open Access Journals (Sweden)

    Morita,Kiyoshi

    2013-04-01

    Full Text Available Patients undergoing a panic attack (PA or a hyperventilation attack (HVA are sometimes admitted to emergency departments (EDs. Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6 and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. We measured each parameter in 21 PA or HVA patients and compared the values with those from 20 volunteers. We found that both Vit B6 and iron levels were significantly lower in the PA/HVA group than in the volunteer group. There was no significant difference in the serum levels of vitamins B2 or B12. These results suggest that low serum concentrations of Vit B6 and iron are involved in PA and HVA. Further studies are needed to clarify the mechanisms involved in such differences.

  1. Low serum concentrations of vitamin B6 and iron are related to panic attack and hyperventilation attack.

    Science.gov (United States)

    Mikawa, Yasuhito; Mizobuchi, Satoshi; Egi, Moritoki; Morita, Kiyoshi

    2013-01-01

    Patients undergoing a panic attack (PA) or a hyperventilation attack (HVA) are sometimes admitted to emergency departments (EDs). Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6) and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. We measured each parameter in 21 PA or HVA patients and compared the values with those from 20 volunteers. We found that both Vit B6 and iron levels were significantly lower in the PA/HVA group than in the volunteer group. There was no significant difference in the serum levels of vitamins B2 or B12. These results suggest that low serum concentrations of Vit B6 and iron are involved in PA and HVA. Further studies are needed to clarify the mechanisms involved in such differences. PMID:23603926

  2. Influence of self-compacting concrete composition on sulfuric acid attack

    OpenAIRE

    Feys, Dimitri; Liu, Zanqun; Heirman, Gert; De Schutter, Geert; Boel, Veerle; Desmet, Bram; Vantomme, John; Cizer, Özlem; Vandewalle, Lucie; Gemert, Dionys van

    2009-01-01

    Sulfuric acid attack on concrete has been reported for over a century. Many scientific papers deal with the issue of concrete damage due to sulfate and sulfuric attack. The introduction of self-compacting concrete introduces new questions related to the behaviour of powder-rich mixtures in a sulfate environment. This paper describes a simple testing method to investigate the influence of the concrete composition on the sulfuric acid attack. Concrete samples have been submerged in a sulfate...

  3. Defense against SYN-Flood Denial of Service Attacks Based on Learning Automata

    OpenAIRE

    Masoud Bekravi; Shahram Jamali; Gholam Shaker

    2012-01-01

    SYN-flooding attack uses the weakness available in TCPs three-way handshake process to keep it from handling legitimate requests. This attack causes the victim host to populate its backlog queue with forged TCP connections. In other words it increases Ploss (probability of loss) and Pa (buffer occupancy percentage of attack requests) and decreases Pr (buffer occupancy percentage of regular requests) in the victim host and results to decreased performance of the host. This paper proposes a sel...

  4. Avoiding Prankster Attack in Case of Selfish Driver Using the Location Aware Fixed Nodes - A Review

    Directory of Open Access Journals (Sweden)

    Namrata Singh

    2014-06-01

    Full Text Available VANET Security is a popular research area and concerns with the automatically driven vehicles. VANETs are prone to number of security breaching methods. These security breaches can be categorized as Replay Attach, Denial of Service, Fabrication Attack, Prankster Attack, etc. These attacks can cause massive traffic congestion, accident or to hurt large number of people with terrorism activities. Prankster Attack is the one, which is launched by sending the false information to other vehicles, which can cause traffic congestion, accident or terrorism activities. In this paper, we are proposing a method to prevent the prankster attack. This attack can be prevented by implementing fixed and location-aware nodes across the road, which can compare the GPS coordinates with its coverage area to make the decision that vehicle is transmitting true or false information.

  5. Development of mental health first aid guidelines for panic attacks: a Delphi study

    OpenAIRE

    Jorm Anthony F; Kelly Claire M; Kitchener Betty A

    2009-01-01

    Abstract Background Panic attacks are common, and while they are not life-threatening events, they can lead to the development of panic disorder and agoraphobia. Appropriate help at the time that a panic attack occurs may decrease the fear associated with the attack and reduce the risk of developing an anxiety disorder. However, few people have the knowledge and skills required to assist. Simple first aid guidelines may help members of the public to offer help to people who experience panic a...

  6. ANALYSIS OF DDoS ATTACKS IN DISTRIBUTED PEER TO PEER NETWORKS

    Directory of Open Access Journals (Sweden)

    Vooka Pavan Kumar

    2011-08-01

    Full Text Available The term ‘peer-to-peer’ generally describes a class of systems that employ distributed resources to perform a specific function in a decentralized manner. Distributed P2P networks are widely used for file sharing and in such a scenario, a Distributed P2P network could be easily exploited by an attacker to establish a DDoS attack against any arbitrary host on the internet. Distributed denials of service (DDoS attacks are very hard to detect and regarded as a major threat to the Internet. Though a number of techniques have been proposed to defeat DDoS attacks in Distributed P2P networks, it is still very hard to respond to flooding- based DDoS attacks due to a large number of attacking machines and the use of source- address spoofing. An efficient framework has been designed to detect and defend against DDoS attacks in Distributed Peer-to-Peer networks. It defends against attacks by considering the distance between the source ends and the victim end and also the Time-to-Live (TTL value in IP header. The proposed system has three major components: DDoS detection, agent-based trace back, and traffic control. The agent based mechanism is used to keep track of all the node details (e.g. bandwidth, node capacity, etc. The proposed system can be evaluated on a network simulation platform called NS2. The results demonstrate that the detection techniques are capable of detecting DDoS attacks accurately, and the defence mechanism can efficiently control attack traffic in order to maintain the quality of service for legitimate traffic. Also, the framework shows better performance in defeating the DDoS attacks in Distributed P2P networks compared to the other existing techniques. Keywords- Distributed Peer-to-Peer Networks, Distributed Denial of Service Attack, Time-to-Live, Internet Protocol

  7. A Formal Proof of Countermeasures against Fault Injection Attacks on CRT-RSA

    OpenAIRE

    Rauzy, Pablo; Guilley, Sylvain

    2014-01-01

    In this article, we describe a methodology that aims at either breaking or proving the security of CRT-RSA implementations against fault injection attacks. In the specific case-study of the BellCoRe attack, our work bridges a gap between formal proofs and implementation-level attacks. We apply our results to three implementations of CRT-RSA, namely the unprotected one, that of Shamir, and that of Aum\\"uller et al. Our findings are that many attacks are possible on both the unprotected and the...

  8. Cognitive models for the concept of angle

    OpenAIRE

    Matos, José Manuel Leonardo de

    1999-01-01

    The instructional models taught in class were similar to the students' models. The teachers addressed angle as a basic-level category, discussed its submodels, clarified the boundaries, and established cognitive reference points. They gradually increased the use of complex metaphors and of several models. The study enriched the characterization of the first two levels of van Hiele theory and demonstrated the value of categorization theory in understanding how our comprehension ...

  9. Seven Deadliest Network Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Prowell, Stacy J [ORNL; Borkin, Michael [None; Kraus, Robert [Solutionary, Inc.

    2010-05-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting networks? Then you need "Seven Deadliest Network Attacks". This book pinpoints the most dangerous hacks and exploits specific to networks, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Denial of Service; War Dialing; Penetration 'Testing'; Protocol Tunneling; Spanning Tree Attacks; Man-in-the-Middle; and, Password Replay. Knowledge is power, find out about the most dominant attacks currently waging war on computers and networks globally. Discover the best ways to defend against these vicious attacks; step-by-step instruction shows you how. Institute countermeasures, don't be caught defenseless again, learn techniques to make your computer and network impenetrable.

  10. A simple coherent attack and practical security of differential phase shift quantum cryptography

    International Nuclear Information System (INIS)

    The differential phase shift quantum key distribution protocol reveals good security against such powerful attacks as unambiguous state discrimination and beam splitting attacks. Its complete security analysis is complex due to high dimensions of the supposed spaces and density operators. In this paper, we consider a particular and conceptually simple coherent attack, available in practical implementations. The main condition for this attack is the length of used coherent state tuples of order 8–12. We show that under this condition, no high level of practical distance between legitimate users can be achieved. (paper)

  11. Therapeutic attack of hypoxic cells of solid tumors: presidential address.

    Science.gov (United States)

    Sartorelli, A C

    1988-02-15

    Hypoxic cells of solid tumors are relatively resistant to therapeutic assault. Studies have demonstrated that oxygen-deficient tumor cells exist in an environment conducive to reductive reactions making hypoxic cells particularly sensitive to bioreductive alkylating agents. Mitomycin C, the prototype bioreductive alkylating agent available for clinical use, is capable of preferentially killing oxygen-deficient cells both in vitro and in vivo. This phenomenon is at least in part the result of differences in the uptake and metabolism of mitomycin C by hypoxic and oxygenated tumor cells, with the ultimate critical lesion being the cross-linking of DNA by the mitomycin antibiotic. The combination of mitomycin C with X-irradiation, to attack hypoxic and oxygenated tumor cell populations, respectively, has led to enhanced antitumor effects in mice bearing solid tumor implants and in patients with cancer of the head and neck. More efficacious kill of hypoxic tumor cells may be possible by the use of dicoumarol in combination with mitomycin or by the use of the related antibiotic porfiromycin. The findings support the use of an agent with specificity for hypoxic tumor cells in potentially curative regimens for solid tumors. PMID:3123053

  12. Multi-Layer Approach for the Detection of Selective Forwarding Attacks

    Directory of Open Access Journals (Sweden)

    Naser Alajmi

    2015-11-01

    Full Text Available Security breaches are a major threat in wireless sensor networks (WSNs. WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD. The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable.

  13. Multi-Layer Approach for the Detection of Selective Forwarding Attacks.

    Science.gov (United States)

    Alajmi, Naser; Elleithy, Khaled

    2015-01-01

    Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD). The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable. PMID:26610499

  14. Stress-related changes in toddlers and their mothers following the attack of September 11.

    Science.gov (United States)

    Conway, Anne; McDonough, Susan C; MacKenzie, Michael J; Follett, Chantal; Sameroff, Arnold

    2013-10-01

    Unlike other forms of disaster, terrorism is not confined to a particular place or time, and recent evidence indicates that the 9/11 terrorist attack was a significant macrolevel stressor affecting the health and mental health of United States citizens. No studies, however, have reported symptoms in toddlers and their mothers both before and after the attacks. To address this gap, we examined the effects of the 9/11 terrorist attacks on mothers and their 33-month-old toddlers. The attacks occurred during data collection at 33 months of a longitudinal study. Thirty-three-month-old toddlers and mothers who were assessed after the attacks were compared with those assessed before the attacks. When changes were examined from a previous wave of data collected at 15 months, those in the after-attack group showed poorer health, lower child acceptance, and marginally more anxiety, and their toddlers cried more and slept less, whereas the before-attack group showed no changes. Our findings contribute to research documenting widespread effects of the 9/11 terrorist attack on stress-related symptoms and suggest that greater attention must be placed on the needs of our youngest citizens and their caregivers. PMID:24164525

  15. Effective Authentication Technique for Distributed Denial of Service Attacks in Wireless Local Area Networks

    Directory of Open Access Journals (Sweden)

    S. Sathiyabama

    2012-01-01

    Full Text Available Problem statement: In 802.11-based Wireless LAN (WLAN, there is an mproved risk of security attacks. To defeat concealed attacks, there is a necessity to authenticate both access points and wireless stations. Approach: We propose a defensive technique for DDoS attack in WLAN. This authentication technique includes an Authentication Server (AS in addition to the Wireless Station (WS and Access Point (AP. Results: The authentication server holds both normal and attacker databases. The attacker database can be constructed from the outcome of fuzzy decision making. After WS and AP registers itself with AS, WS sends authentication request message to AS through the nearest AP. Before granting the session key for the WS, the AS checks the occurrence of WS in the attacker database. If it is found to be an attacker, AS denies the session key for the WS, there by isolating the WS from further communications. In order to prevent the authentication request flooding attacks, traffic pattern filtering rule is implemented. Conclusion/Recommendations: By simulation results, we show that the proposed technique is more efficient defensive mechanism against DDoS attack.

  16. Resilience of gated avalanche photodiodes against bright illumination attacks in quantum cryptography

    CERN Document Server

    Yuan, Z L; Shields, A J; 10.1063/1.3597221

    2011-01-01

    Semiconductor avalanche photodiodes (APDs) are commonly used for single photon detection in quantum key distribution. Recently, many attacks using bright illumination have been proposed to manipulate gated InGaAs APDs. In order to devise effective counter-measures, careful analysis of these attacks must be carried out to distinguish between incorrect operation and genuine loopholes. Here, we show that correctly-operated, gated APDs are immune to continuous-wave illumination attacks, while monitoring the photocurrent for anomalously high values is a straightforward counter-measure against attacks using temporally tailored light.

  17. Perceptions of tilt angles of an agricultural tractor.

    Science.gov (United States)

    Görücü, Serap; Cavallo, Eugenio; Murphy, Dennis

    2014-01-01

    A tractor stability simulator has been developed to help study tractor operators' perceptions of angles when the simulator is tilted to the side. The simulator is a trailer-mounted tractor cab equipped with hydraulic lift that can tilt the tractor cabin up to 30 degrees. This paper summarizes data from 82 participants who sat in the simulator while it was tilted. Demographic variables, estimates of tilt angles, and measured tilt angles were collected. The effects of age, gender, tractor driving experience, and frequency of operation on the estimated and measured tilt angles were analyzed. The results showed that about 50% of the participants reported estimations of side tilt angles within ±5 degrees of the actual angles, and nearly the same percentage overestimated the actual side tilt angles. Only a small percentage underestimated the angles. Older, more experienced, and male participants set higher limits on the actual angle at which they felt uncomfortable and would not drive. PMID:24417527

  18. Treatment response after repeated administration of C1 esterase inhibitor for successive acute hereditary angioedema attacks.

    Science.gov (United States)

    Craig, Timothy J; Bewtra, Againdra K; Hurewitz, David; Levy, Robyn; Janss, Gerti; Jacobson, Kraig W; Packer, Flint; Bernstein, Jonathan A; Rojavin, Mikhail A; Machnig, Thomas; Keinecke, Heinz-Otto; Wasserman, Richard L

    2012-01-01

    Placebo-controlled studies established the efficacy of replacement therapy with C1 esterase inhibitor (C1-INH) concentrate for treating single acute hereditary angioedema (HAE) attacks, but only limited data from prospective studies are available on repeated treatment of successive HAE attacks. This study evaluates the association between repeated treatments with 20 U/kg of C1-INH concentrate (Berinert; CSL Behring, Marburg, Germany) for HAE attacks at any body location and treatment response. In a post hoc analysis of an open-label extension study (International Multicenter Prospective Angioedema C1-INH Trial [I.M.P.A.C.T.2]), the association between repeated treatment with C1-INH and times to onset of symptom relief and complete resolution of HAE symptoms was assessed in patients who were treated for at least 15 attacks by linear regression on the ordinal attack number. Eighteen patients received C1-INH concentrate for at least 15 HAE attacks over a mean duration of 34 months. Demographic and baseline characteristics of these patients were similar to those of all patients in the study. The distribution of body locations and the intensity of HAE attacks were similar for each of the first 15 attacks and subsequent attacks. The extent of previous use of C1-INH concentrate had no effect on the time to onset of symptom relief, the time to complete resolution of HAE symptoms, or the time between attacks treated with C1-INH concentrate; the median of individual linear regression coefficients was not statistically significantly different from 0. Treatment with 20 U/kg of C1-INH concentrate provided consistent treatment response in patients treated for multiple successive HAE attacks at any body location. (Clinicaltrials.gov identifier: NCT00292981). PMID:22856636

  19. Prospective, double-blind, placebo-controlled trials of ecallantide for acute attacks of hereditary angioedema.

    Science.gov (United States)

    Stolz, Leslie E; Sheffer, Albert L

    2012-01-01

    Hereditary angioedema (HAE) is a rare genetic disorder characterized by unpredictable, episodic, incapacitating attacks of well-demarcated angioedema in the absence of urticaria and pruritus. HAE is due to deficient or dysfunctional C1-esterase inhibitor activity, which results in unopposed activation of plasma kallikrein, resulting in increased levels of bradykinin. Ecallantide is a potent and specific plasma kallikrein inhibitor approved for the treatment of acute attacks of HAE affecting any anatomic site. In Phase III clinical trials, subcutaneously administered ecallantide demonstrated significant, rapid and durable symptom relief. Ecallantide was effective for all attack types, including potentially life-threatening laryngeal attacks. The main safety concern is potentially serious hypersensitivity reactions, including anaphylaxis. Ecallantide represents an important treatment option for the management of acute attacks of HAE. PMID:22149337

  20. Effect of hydrogen attack on acoustic emission behavior of low carbon steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to investigate the effect of hydrogen attack degree on acoustic emission (AE) behavior of low carbon steel during tensiling, specimens made of low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.

  1. A PROFICIENT TRACEBACK APPROACH USING PROVINCIAL LOCALITY ASPECTS TO ELIMINATE DENIAL OF SERVICE ATTACKS

    Directory of Open Access Journals (Sweden)

    S. Periyasamy

    2013-01-01

    Full Text Available A Denial-of-Service (DoS attack, a menace to the availability of resources and service to the intended user, is usually by augmenting the traffic in the communication medium. These attacks originate in either ways, internal or external to a network with the aim to suspend the legitimate user from getting his/her service. The DoS attacks have been countered through various approaches, yet this problem remains stable in field. The traceback mechanisms of the attacker necessitate a large amount of valuable information which is usually hidden by the attacker or not documented in the network. Moreover the network has strict constraints over the usage of memory resources by the nodes and routers, equivalent to an empty memory nature. The amount of data reasonably required for computation would increase the processing delay which is usually unexpected. The counter measures proposed tried to detect the network under attack or to track the attacker with some degree of information available. Nowadays these attacks have evolved to break out from all those detection approaches with greater immunity to not reveal their identity. This study works with the physical zone addresses to detect and traceback the identity of the attacker. The packet sent from the attacker carries merely the part of its identity. Yet the Provincial Assessment Attributes (PAA possesses the geographical locality aspects in terms of Continent Code, Country Code, State Codes and the Area Codes along with its IP address. Accepting the factor that IP is spoofed in most cases, the routers in the path are still able to keep track of these PAA prospects irrespective of the faked IP. Hence this mechanism could be implemented with minimal computation, leading to the attacker with considerable and fruitful results in identifying the same. Besides, this method takes deep care to authenticate and not to affect the traffic of legitimate users.

  2. Analysis of AODV and DSR in Presence of Wormhole Attack in Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    VIVEK SHARMA,

    2010-11-01

    Full Text Available An ad hoc network is a collection of mobile nodes that dynamically form a temporary network. It operates without the use of existing infrastructure. As mobile ad hoc network applications are deployed, security emerges as a central requirement. In this paper, we introduce the wormhole attack, a severe security attack in ad hocnetworks that is particularly challenging to defend against. The wormhole attack is possible even if the attacker has not compromised any hosts and even if all communication provides authenticity and confidentiality. In the wormhole attack, an attacker records packets (or bits at one location in the network, tunnels them (possiblyselectively to another location, and retransmits them there into the network. The wormhole attack can form a serious threat in wireless networks, especially against many ad hoc network routing protocols and locationbased wireless security systems. This paper analyses the performance of AODV and DSR routing protocols with and without wormhole attack. This would be a great help for the people conducting research on real world problems in MANET security.

  3. Attack or attacked: The sensory and fluid mechanical constraints of copepods’ predator–prey interactions

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2013-01-01

    Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding, and mechani...

  4. Attack Coverage in High-Level Men’s Volleyball: Organization on the Edge of Chaos?

    Directory of Open Access Journals (Sweden)

    Laporta Lorenzo

    2015-09-01

    Full Text Available Change is pervasive, but emerging patterns are occasionally detectable through analysis of systemic behaviors. Match analysis uses these patterns in order to reduce the degree of improvisation and to optimize the training process. However, it is possible that certain game phases elude systematic patterning. In this vein, our aim was to analyze the case of attack coverage in men’s volleyball, as we suspected it would elude systematic patterning and has received negligible attention in scientific research. We analyzed the occurrence of attack coverage in 4544 plays of the 2011 Volleyball World League. A Chi-square test with residual adjusted values was applied to explore significant associations between variables. A Monte Carlo correction was applied, as some cells had n<5. Effect sizes were determined using Cramer’s V. Overall, attack coverage occurred in 3.89% of ball possessions, and 23 distinct structures emerged. These structures lacked significant associations with the game complex, setting zone, and effect of attack coverage. Conversely, attack coverage structures showed significant associations with the attack zone and tempo, with very strong effect sizes (V=0.472 and V=0.521, respectively. As certain attack zones are deeply associated with attack tempo, it is apparent that quicker attack plays affect attack coverage structuring, promoting the formation of less complex structures. Ultimately, attack coverage structures seem to depend on momentary constraints, thereby rendering rigid systematization impracticable. Still, we contended that a principle-based approach might be suitable. This invites researchers to rethink how to interpret game regularities.

  5. Attack Coverage in High-Level Men’s Volleyball: Organization on the Edge of Chaos?

    Science.gov (United States)

    Laporta, Lorenzo; Nikolaidis, Pantelis; Thomas, Luke; Afonso, José

    2015-01-01

    Change is pervasive, but emerging patterns are occasionally detectable through analysis of systemic behaviors. Match analysis uses these patterns in order to reduce the degree of improvisation and to optimize the training process. However, it is possible that certain game phases elude systematic patterning. In this vein, our aim was to analyze the case of attack coverage in men’s volleyball, as we suspected it would elude systematic patterning and has received negligible attention in scientific research. We analyzed the occurrence of attack coverage in 4544 plays of the 2011 Volleyball World League. A Chi-square test with residual adjusted values was applied to explore significant associations between variables. A Monte Carlo correction was applied, as some cells had n<5. Effect sizes were determined using Cramer’s V. Overall, attack coverage occurred in 3.89% of ball possessions, and 23 distinct structures emerged. These structures lacked significant associations with the game complex, setting zone, and effect of attack coverage. Conversely, attack coverage structures showed significant associations with the attack zone and tempo, with very strong effect sizes (V=0.472 and V=0.521, respectively). As certain attack zones are deeply associated with attack tempo, it is apparent that quicker attack plays affect attack coverage structuring, promoting the formation of less complex structures. Ultimately, attack coverage structures seem to depend on momentary constraints, thereby rendering rigid systematization impracticable. Still, we contended that a principle-based approach might be suitable. This invites researchers to rethink how to interpret game regularities. PMID:26557208

  6. Liquid Missile Fuels as Means of Chemical Terrorist Attack

    International Nuclear Information System (INIS)

    Modern world is faced with numerous terrorist attacks whose goals, methods and means of the conduct are various. It seems that we have entered the era when terrorism, one's own little terrorism, is the easiest and the most painless way of achieving a goal. That is why that such a situation has contributed to the necessity for strengthening individual and collective protection and safety, import and export control, control of the production and illegal sale of the potential means for delivering terrorist act. It has also contributed to the necessity for devising means of the delivery. For more than 10 years, a series of congresses on CB MTS Industry has pointed at chemicals and chemical industry as potential means and targets of terrorism. The specialization and experience of different authors in the field of the missile technology and missile fuels, especially those of Eastern origin, and the threat that was the reality of the war conflicts in 1990s was the reason for making a scientific and expert analysis of the liquid missile fuels as means of terrorism. There are not many experts in the field of NBC protection who are familiar with the toxicity and reaction of liquid missile fuels still lying discarded and unprotected in abandoned barracks all over Europe and Asia. The purpose of this paper is to draw public attention to possible different abuses of liquid missile fuels for a terrorist purpose, as well as to possible consequences and prevention measures against such abuses. (author)

  7. Detection and Discrimination of DDoS Attacks from Flash Crowd Using Entropy Variations

    Directory of Open Access Journals (Sweden)

    Pragya Katiyar

    2013-08-01

    Full Text Available Internet is a worldwide network that combines millions local to global scope, private public, academics, business, optical network technologies, government networks. It carries an expandable rangeof information resources and services which lead to bulk exchange of traffic over the Internet every day. This excessive popularity creates some troubles in the networks. Among them, Flash Crowd andDistributed Denial of Service (DDoS attacks are the two major events. Web services needs stability and security from these two concerns. There are some methods that can discriminate DDoS attack from flash crowd and trace the sources of the attack in huge volume of network traffic. However, it is difficult to detect the exact sources of DDoS attacks in network traffic when Flash crowd event is also present. Due to the alikeness of these two anomalies, attacker can easily mimic the malicious flow into legitimate traffic patterns and defence system cannot detect real sources of attack on time. In this paper, entropy variation, a theoretic parameter, is used to discriminate DDoS attack from Flash Crowd and trace the sources of theDDoS attack. Entropy variation is a theoretic concept which is a measure of changes in concentration of distribution of flows at a router for a given time duration. The proposed strategy is effective and efficiently scalable that has several advantages like memory non intensive, minimum overhead in terms of resources and time, and independent of traffic pattern.

  8. Review of syn-flooding attack detection mechanism

    CERN Document Server

    Manna, Mehdi Ebady

    2012-01-01

    Denial of Service (DoS) is a security threat which compromises the confidentiality of information stored in Local Area Networks (LANs) due to unauthorized access by spoofed IP addresses. SYN Flooding is a type of DoS which is harmful to network as the flooding of packets may delay other users from accessing the server and in severe cases, the server may need to be shut down, wasting valuable resources, especially in critical real-time services such as in e-commerce and the medical field. The objective of this paper is to review the state-of-the art of detection mechanisms for SYN flooding. The detection schemes for SYN Flooding attacks have been classified broadly into three categories - detection schemes based on the router data structure, detection schemes based on statistical analysis of the packet flow and detection schemes based on artificial intelligence. The advantages and disadvantages for various detection schemes under each category have been critically examined. The performance measures of the cate...

  9. Attack robustness of cascading load model in interdependent networks

    Science.gov (United States)

    Wang, Jianwei; Wu, Yuedan; Li, Yun

    2015-08-01

    Considering the weight of a node and the coupled strength of two interdependent nodes in the different networks, we propose a method to assign the initial load of a node and construct a new cascading load model in the interdependent networks. Assuming that a node in one network will fail if its degree is 0 or its dependent node in the other network is removed from the network or the load on it exceeds its capacity, we study the influences of the assortative link (AL) and the disassortative link (DL) patterns between two networks on the robustness of the interdependent networks against cascading failures. For better evaluating the network robustness, from the local perspective of a node we present a new measure to qualify the network resiliency after targeted attacks. We show that the AL patterns between two networks can improve the robust level of the entire interdependent networks. Moreover, we obtain how to efficiently allocate the initial load and select some nodes to be protected so as to maximize the network robustness against cascading failures. In addition, we find that some nodes with the lower load are more likely to trigger the cascading propagation when the distribution of the load is more even, and also give the reasonable explanation. Our findings can help to design the robust interdependent networks and give the reasonable suggestion to optimize the allocation of the protection resources.

  10. Development of an accelerated test for Internal Sulfate Attack study

    Directory of Open Access Journals (Sweden)

    Khelil Nacim

    2014-04-01

    Full Text Available Internal Sulfate Attack (ISA is a pathology that occurs under certain conditions in concrete having undergone heating above 70 °C at early age (through heating in pre-casting industry or due to hydration in large concrete parts. This reaction deemed very slow, numerous methods to speed up reactions leading to delayed ettringite formation have been developed. These methods are all based on the material damage. Another type of test is currently under development. It is based on rehabilitation techniques such as electrochemical chloride extraction (ECE in order to accelerate the leaching of alkalis that could be one of the triggers of the pathology. The study presented in this paper focused on concrete specimens prepared from cement (CEM I 52.5 N enriched with Na2SO4. These concretes have undergone a heat treatment typical of those used in precast plants (up to 24 hours with a maximum temperature of 80 °C. Various paths were explored for the development of the accelerated test. The first results showed that it was necessary to use a removable titanium anode ruthenium anode instead of stainless steel embedded in the concrete. Then tests with de-ionized water as the solute to the cathode did not accelerate the onset of expansions. The experiment has been modified and potassium carbonate was added to the solution. This modification didn’t show any significant improvement, and other experiments are being carried out to explain this result.

  11. Usefulness of chest radiographs in first asthma attacks

    International Nuclear Information System (INIS)

    To assess the value of routine chest radiography during acute first attacks of asthma, we studied 371 consecutive children over one year of age who presented with an initial episode of wheezing. Three hundred fifty children (94.3%) had radiographic findings that were compatible with uncomplicated asthma and were considered negative. Twenty-one (5.7%) had positive findings: atelectasis and pneumonia were noted in seven, segmental atelectasis in six, pneumonia in five, multiple areas of subsegmental atelectasis in two, and pneumomediastinum in one. The patients with positive films were more likely to have a respiratory rate above 60 or a pulse rate above 160 (P < 0.001), localized rales or localized decreased breath sounds before treatment (P < 0.01), and localized rales (P < 0.005) and localized wheezing (P < 0.02) after treatment; also, these patients were admitted to the hospital more often (P < 0.001). Ninety-five percent (20 of 21) of the children with positive films could be identified before treatment on the basis of a combination of tachypnea, tachycardia, fever, and localized rales or localized decreased breath sounds. Most first-time wheezers will not have positive radiographs; careful clinical evaluation should reveal which patients will have abnormal radiographs and will therefore benefit from the procedure. 20 references, 3 tables

  12. Review Of Syn-Flooding Attack Detection Mechanism

    Directory of Open Access Journals (Sweden)

    Mehdi Ebady Manna

    2012-02-01

    Full Text Available Denial of Service (DoS is a security threat which compromises the confidentiality of information stored in Local Area Networks (LANs due to unauthorized access by spoofed IP addresses. SYN Flooding is a type of DoS which is harmful to network as the flooding of packets may delay other users from accessing the server and in severe cases, the server may need to be shut down, wasting valuable resources, especially in critical real-time services such as in e-commerce and the medical field. The objective of this paper is to review the state-of-the art of detection mechanisms for SYN flooding. The detection schemes for SYN Flooding attacks have been classified broadly into three categories – detection schemes based on the router data structure, detection schemes based on statistical analysis of the packet flow and detection schemes based on artificial intelligence. The advantages and disadvantages for various detection schemes under each category have been critically examined. The performance measures of the categories have also been compared.

  13. Invulnerability of grown Peer-to-Peer networks under progressive targeted attacks

    Science.gov (United States)

    Peng, Hao; Zhao, Dandan; Han, Jianmin; Lu, Jianfeng

    2015-06-01

    Security issues of Peer-to-Peer (P2P) networks have attracted more and more research in recent years. In this paper, using complex features of P2P networks, we shift the focus to the study of invulnerability of grown P2P networks under progressive targeted attacks. Based on dynamic process and reverse percolation theory, we present several mechanisms that attacked P2P networks can adopt to minimize the disasters aftermath progressive targeted attacks. In this process, we proposed: (i) the dynamics of grown P2P networks under targeted attacks can make sure an attacked P2P network restore a power-law (PL) characteristic to a normal level; (ii) a global degree restoring process from the aftermath of progressive targeted attacks can restore the status of set of high degree peers to normal; (iii) a reverse percolation process glues the fragmented small connected component of a destroyed grown P2P network into a giant connected component (GCC). Experimental results show that an attacked grown P2P network can restore the key characteristics, such as power-law characteristic of original P2P network, the set of high degree peers and the giant connected component, to a regular status. In this way, we can illustrate the invulnerability of progressive targeted attacks on grown P2P networks which is particularly useful in designing complex P2P networks.

  14. Structural basis of complement membrane attack complex formation

    Science.gov (United States)

    Serna, Marina; Giles, Joanna L.; Morgan, B. Paul; Bubeck, Doryen

    2016-02-01

    In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a `multi-hit' mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a `split-washer' configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration.

  15. New Framework to Detect and Prevent Denial of Service Attack in Cloud Computing Environment

    Directory of Open Access Journals (Sweden)

    Mohd Nazri Ismail

    2012-08-01

    Full Text Available Cloud computing paradigm as one of new concept in world of computing in general and especially in computer network, give a new facilities such as IaaS (infrastructure as service, PaaS (platform as stricter and SaaS (software as service. All this services offered by utilization of new and old techniques such as resources sharing distributed networking, virtualization. But it still suffering from some shortages and one of the most important one is security threats. and one of the most dangers is Distributed denial-of-service (DDoS, and for overcome this threat many techniques has been proposed and most of them give more attention to one aspect either detecting or preventing or tracing the sources of attack and a few which address the attack in all its aspect. here we propose new framework to counter this attack by detect the attack using covariance matrix statistical method and determine the sources of attack using TTl Distance average and Finlay we apply a technique to eliminate attack by get benefit from the Honeypot method to block all attacks sources and transfer the legitimate traffic to another virtual machine not affected by attack.

  16. Development of an Attack-Resistant and Secure SCADA System using WSN, MANET, and Internet

    Directory of Open Access Journals (Sweden)

    N. Rajesh kumar

    2014-06-01

    Full Text Available Industrial Control Systems (ICS are open to security attacks when they are integrated with IT systems and wireless technologies for enhanced processing and remote control. These Critical Infrastructures (CIs are highly important as they provide service for an entire nation and causes serious danger even when interrupted for a while. Some of the common SCADA (Supervisory Control and Data Acquisition systems involve energy and water distribution systems. In this paper, the energy distribution SCADA system comprising several substations is considered. A secure framework is proposed that combines the energy control system with Wireless Sensor Networks (WSNs, Mobile Ad hoc Networks (MANETs, and the Internet, providing anomaly prevention and status management. SCADA attacks occur at the state estimators of the power systems which are used to route power flows and detect faulty devices. These estimators are located in the SCADA control center which is a sensitive area and measurements must be transmitted over a secure communication channel. The attack-resistance of the SCADA system is enhanced by increasing the hardness and complexity of the attack problem. The Attack-Resistant and Secure (ARS SCADA system is evaluated against existing techniques like NAMDIA (Network-Aware Mitigation of Data Integrity Attacks, Retrofit IDS (Intrusion Detection System, and CSBF (Critical State-Based Filtering for enhancing the attack-resistance and security of SCADA systems. It is found that the performance of ARS SCADA system is good compared to the existing methods in terms of maximum normalized attack impact and latency.

  17. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.

    Science.gov (United States)

    Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y

    2016-04-01

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures. PMID:25847370

  18. Cerebral blood flow velocities are reduced during attacks of unilateral migraine without aura

    DEFF Research Database (Denmark)

    Thomsen, L L; Iversen, Helle Klingenberg; Olesen, J

    1995-01-01

    It has been disputed whether or not large intracranial arteries are dilated during migraine attacks. In order to answer this question the present transcranial Doppler study focused on side-to-side differences of middle cerebral artery blood velocity during unilateral attacks of migraine without...... aura in 25 patients. Blood velocity in the middle cerebral artery was lower on the headache side (59 cm/s) than on the non-headache side (65 cm/s) during the migraine attack. No such difference was found outside of attack (65 cm/s both sides). The difference (headache side minus non-headache side) was...... on average -6.1 cm/s during attack compared to -0.4 cm/s outside of attack (p = 0.01). Assuming that rCBF is unchanged during attacks of migraine without aura, our results suggest a 9% increase in middle cerebral artery lumen (cross-sectional area) on the affected side during unilateral attacks of...

  19. Effect of Black Hole Active Attack on Reactive Routing Protocol AODV in MANET using Network Simulator

    Directory of Open Access Journals (Sweden)

    Arunima Patel

    2013-01-01

    Full Text Available Mobile Ad-Hoc Network is a collection of mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on continual basis. MANET has potential applications in very unpredictable and dynamic environments. Due to security vulnerabilities of the routing protocols, wireless ad-hoc networks are unprotected to attacks of the malicious nodes. One of these attacks is the Black Hole Attack. In this paper, we focus on analyzing the effect of active Black Hole Attack on one of famous reactive routing protocol AODV. Our aim is to simulate the effect of Black Hole Attack on AODV protocol using various performance metric parameters.

  20. Seven Deadliest Wireless Technologies Attacks

    CERN Document Server

    Haines, Brad

    2010-01-01

    How can an information security professional keep up with all of the hacks, attacks, and exploits? One way to find out what the worst of the worst are is to read the seven books in our Seven Deadliest Attacks Series. Not only do we let you in on the anatomy of these attacks but we also tell you how to get rid of them and how to defend against them in the future. Countermeasures are detailed so that you can fight against similar attacks as they evolve. Attacks featured in this book include:Bluetooth AttacksCredit Card, Access Card, and Passport AttacksBad Encryption

  1. Calibration of 5-hole Probe for Flow Angles from Advanced Technologies Testing Aircraft System Flight Data

    Directory of Open Access Journals (Sweden)

    Y. Parameswaran

    2004-04-01

    Full Text Available This paper describes the investigations carried out to calibrate the 5-hole probe for flow angles from advanced technologies testing aircraft system flight data. The flight tests were carriedout with gear up and at nominal mid-centre of gravity location for two landing flap positions, Of= IN and 14°. Dynamic manoeuvres were executed to excite the short period and Dutch roll mode of the aircraft. In addition, pull up, push down and steady sideslip manoeuvres were also carried out. The data compatibility check on the recorded flight data has been carried out using maximum likelihood output error algorithm to estimate the bias, scale factor, and time delay in the pressure measurements from the 5-hole probe mounted on a noseboom in front of aircraft nose . Through a way of kinematic consistency checking, flight-validated scale factors, biases, and time delays are determined for the differential pressure measurements for both angle of attack and angle of sideslip. Also, the dynamic pressure measurement is found to have time delays. Based on the earlier investigations, it is once again confirmed that the measurements of attitude angles, obtained from the inertial platform, clearly indicate time delays referred to the other signals like linear accelerations and angular rates which are measured with the dedicated flight instrumentation package.The identified time delays in attitude angles agreed well with the inertial platform specifications. The estimates of sensitivity coefficients and scale factors from the flight data analysis correlates reasonably well with the manufacturer Rosemount calibration curves for the tested Mach range 0.23-0.53 . The flight data analysis at Mach number of about 0.59 indicateMach dependency for the angle of attack.

  2. Numerical simulation of wave attack on sea dike with asphalt concrete revetment

    NARCIS (Netherlands)

    Jassim, I.; Tan, S.; Vermeer, P.A.; Hicks, M.A.

    2012-01-01

    The numerical simulation of wave attack on a sea dike with an asphalt concrete revetment during a severe storm is carried out using the dynamic Finite Element Method. When wave loads attack the revetment during such a storm, both the revetment and the underlying soil may be damaged. The two-phase fl

  3. Single-cell transcript profiling of barley attacked by the powdery mildew fungus

    DEFF Research Database (Denmark)

    Gjetting, Torben; Hagedorn, Peter; Schweizer, Patrick; Thordal-Christensen, Hans; Carver, Timothy L. W.; Lyngkjær, Michael Foged

    2007-01-01

    In many plant-pathogen interactions, there are several possible outcomes for simultaneous attacks on the same leaf. For instance, an attack by the powdery mildew fungus on one barley leaf epidermal cell may succeed in infection and formation of a functional haustorium, whereas a neighboring cell...

  4. PERFORMANCE ANALYSIS OF ADHOC ON DEMAND DISTANCE VECTOR PROTOCOL WITH BLACKHOLE ATTACK IN WSN

    Directory of Open Access Journals (Sweden)

    Adnan Ahmed

    2014-01-01

    Full Text Available The security is major challenging issue in wireless sensor network applications because they are operated in public and unrestrained areas which also makes difficult to protect against tampering or captured by an adversary force that can launch insider attacks to make a node compromised. One type of such attack is black hole attack. Existing AODV routing protocol does not have mechanism to defend against such attacks. In this study, we comprehensively investigates the performance of AODV protocol by simulating it on the various network parameters with various number of blackhole nodes. The metrics for evaluation has been considered as packet delivery ratio, end to end delay, normalized routing overhead and total number of packets drop. The simulation results show that blackhole attack severely degrades the performance of WSN.

  5. Nocturnal panic attacks

    OpenAIRE

    Lopes Fabiana L; Nardi Antonio E; Nascimento Isabella; Valença Alexandre M.; Zin Walter A.

    2002-01-01

    The panic-respiration connection has been presented with increasing evidences in the literature. We report three panic disorder patients with nocturnal panic attacks with prominent respiratory symptoms, the overlapping of the symptoms with the sleep apnea syndrome and a change of the diurnal panic attacks, from spontaneous to situational pattern. The implication of these findings and awareness to the distinct core of the nocturnal panic attacks symptoms may help to differentiate them from sle...

  6. Effect of Helicobacter Pylori Treatment on the Number and Intensity of Migraine Attacks

    Directory of Open Access Journals (Sweden)

    Alireza Bakhshipour

    2012-06-01

    Full Text Available Background: Migraine is a common headache with an unknown cause. Migraine is about three times more common in women (18.2% than in men (6.2%. The recent studies have posed the possible relationship between the Helicobacter pylori infection and migraine headache. This study tries to analyze the effect of treating H. pylori infection on number and severity of migraine attacks.Materials and Methods: In this clinical pilot study, a number of 60 patients with migraine were examined in terms of infecting with H. pylori. Patients with the infections were treated by H. pylori eradication treatment standard triple regimen and the frequency and severity of their migraine attacks were measured for three months and finally the average of frequency and severity of attacks before and after treatment were compared. Results: The average frequency of the migraine attacks in patients with the H.pylori infection who have been treated was 7.1 before treatment and 2.7 after treatment (p=0.001. Likewise, the severity rate of such attacks in such patients was 9 which decreased to 4.5 after treatment (p=0.002. Conclusion: According to our study, patients with migraine attacks are preferred to be examined tested in terms of infecting with H. pylori. Thus, and eradication of this infection can be effective in decreasing of the migraine attacks.

  7. A Review of Current Routing Attacks in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rashid Hafeez Khokhar

    2008-11-01

    Full Text Available A mobile ad hoc network (MANET is a dynamic wireless network that can be formed without any pre-existing infrastructure in which each node can act as a router. MANET has no clear line of defense, so, it is accessible to both legitimate network users and malicious attackers. In the presence of malicious nodes, one of the main challenges in MANET is to design the robust security solution that can protect MANET from various routing attacks. Different mechanisms have been proposed using various cryptographic techniques to countermeasure the routing attacks against MANET. However, these mechanisms are not suitable for MANET resource constraints, i.e., limited bandwidth and battery power, because they introduce heavy traffic load to exchange and verifying keys. In this paper, the current security issues in MANET are investigated. Particularly, we have examined different routing attacks, such as flooding, blackhole, link spoofing, wormhole, and colluding misrelay attacks, as well as existing solutions to protect MANET protocols.

  8. Contact angles of liquid metals on quasicrystals

    International Nuclear Information System (INIS)

    Wetting with μm-sized Pb droplets on thin polycrystalline films of decagonal Al13Co4 is reported. The films were prepared under high vacuum conditions in order to have Pb droplets lying on a clean surface. The method used is sequential deposition and annealing of specific stackings of Al and Co layers of nanometric thicknesses. A 300 nm thick Pb slab was then deposited on top of the films and dewetting experiments were followed in situ in a scanning Auger microprobe. The contact angle between the Pb droplet and the surface of the film is measured to be 49 deg. ± 7 deg. Further investigation performed by cross section transmission electron microscopy allows us to better characterize the interface. Taking into account the rugosity of the film, it is concluded that there is partial wetting of the film, which corresponds to a smaller contact angle. The comparison with other results obtained either with pure metals or with a cubic AlCo compound leads to the conclusion that the wetting behaviour of Pb on the surface of a decagonal compound is close to that of a metal with a high melting point and not significantly different from that of a crystalline compound with a small unit cell

  9. Modelling the attack success of planktonic predators: patterns and mechanisms of prey size selectivity

    DEFF Research Database (Denmark)

    Caparroy, P.; Thygesen, Uffe Høgsbro; Visser, Andre

    2000-01-01

    A mathematical model of the attack success of planktonic predators (fish larvae and carnivorous copepods) is proposed. Based on a geometric representation of attack events, the model considers how the escape reaction characteristics (speed and direction) of copepod prey affect their probability of...... being captured. By combining the attack success model with previously published hydrodynamic models of predator and prey perception, we examine how predator foraging behaviour and prey perceptive ability affect the size spectra of encountered and captured copepod prey. We examine food size spectra of (i...

  10. Process of attack of uraniferous ores by a solution of potassium carbonate and bicarbonate

    International Nuclear Information System (INIS)

    Oxidizing attack process of uraniferous ores by an aqueous solution of potassium carbonate and dicarbonate in which is introduced a gas containing oxygen under pressure. This process allowing a high solubilization of uranium in a soluble salt form

  11. Attack warning

    Energy Technology Data Exchange (ETDEWEB)

    1988-12-01

    The North American Aerospace Defense Command, located at Cheyenne Mountain Air Force Station, is responsible for warning the United States and Canadian leaders that North America is under air, missile, or space attack. The Air Force has been developing a replacement for NORAD's communications computer system, and it expects to spend about $281 million on this program-about $72 million for block I and $209 million for block II. Block I of the replacement system has experienced significant schedule and performance problems, such as the inability to meet the requirement for the unit to restore full mission capability within 267 minutes after a total loss of power, and the incompatibility of the unit with other computer equipment due to the wiring standard. These problems have pushed the planned installation data from 1986 to 1999. The Air Force intends to have the contractor correct the deficiencies during block II development. This report discusses how the replacement program should be reassessed.

  12. Brain-heart connection and the risk of heart attack.

    Science.gov (United States)

    Singh, R B; Kartik, C; Otsuka, K; Pella, D; Pella, J

    2002-01-01

    Autonomic functions, such as increased sympathetic and parasympathetic activity and the brain's suprachiasmatic nucleus, higher nervous centres, depression, hostility and aggression appear to be important determinants of heart rate variability (HRV), which is, itself, an important risk factor of myocardial infarction, arrhythmias, sudden death, heart failure and atherosclerosis. The circadian rhythm of these complications with an increased occurrence in the second quarter of the day may be due to autonomic dysfunction as well as to the presence of excitatory brain and heart tissues. While increased sympathetic activity is associated with increased levels of cortisol, catecholamines, serotonin, renin, aldosterone, angiotensin and free radicals; increased parasympathetic activity may be associated with greater levels of acetylecholine, dopamine, nitric oxide, endorphins, coenzyme Q10, antioxidants and other protective factors. Recent studies indicate that hyperglycemia, diabetes, hyperlipidemia, ambient pollution, insulin resistance and mental stress can increase the risk of low HRV. These risk factors, which are known to favour cardiovascular disease, seem to act by decreasing HRV. There is evidence that regular fasting may modulate HRV and other risk factors of heart attack. While exercise is known to decrease HRV, exercise training may not have any adverse effect on HRV. In a recent study among 202 patients with acute myocardial infarction (AMI), the incidence of onset of chest pain was highest in the second quarter of the day (41.0%), mainly between 4.0-8.0 AM, followed by the fourth quarter, usually after large meals (28.2%). Emotion was the second most common trigger (43.5%). Cold weather was a predisposing factor in 29.2% and hot temperature (> 40 degrees celsius) was common in 24.7% of the patients. Dietary n-3 fatty acids and coenzyme Q10 have been found to prevent the increased circadian occurrence of cardiac events in our randomized controlled trials

  13. Evaluation of the slag attack resistance of high alumina refractory free cement castable

    International Nuclear Information System (INIS)

    The slag attack resistance is a very important property when the life time of refractory castable needs to be improved. The substitution of calcium aluminate cement by a free calcium hydraulic blinder has show a viable way to enhance the thermomechanical performance presented by these materials. At the present very few information is found regarding the slag attack of these free cement castable. In this study the slag attack resistance of high alumina castable with and without cement was evaluated by static test. The corroded region was analyzed by SEM and EDS. (author)

  14. Seven Deadliest Network Attacks

    CERN Document Server

    Prowell, Stacy; Borkin, Mike

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting networks? Then you need Seven Deadliest Network Attacks. This book pinpoints the most dangerous hacks and exploits specific to networks, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Denial of Service War Dialing Penetration "Testing" Protocol Tunneling Spanning Tree At

  15. Seven deadliest USB attacks

    CERN Document Server

    Anderson, Brian

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting USB technology? Then you need Seven Deadliest USB Attacks. This book pinpoints the most dangerous hacks and exploits specific to USB, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: USB Hacksaw USB Switchblade USB Based Virus/Malicous Code Launch USB Device Overflow RAMdum

  16. Seven Deadliest Microsoft Attacks

    CERN Document Server

    Kraus, Rob; Borkin, Mike; Alpern, Naomi

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting Microsoft products? Then you need Seven Deadliest Microsoft Attacks. This book pinpoints the most dangerous hacks and exploits specific to Microsoft applications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Windows Operating System-Password AttacksActive Directory-Escalat

  17. Efficiency of actions in attack of diagonal players in female volleyball

    OpenAIRE

    Yevgeniya Strelnykova; Tamara Liakhova

    2016-01-01

    Strelnikova Ye., Lyakhova T.  Purpose: to define efficiency of technical and tactical actions of the diagonal player in the attacking actions of a team depending on schemes of a defensive play of the rival. Material & Methods: the competitive process with participation of 10 players of the role –the diagonal forward of qualification and the adult category was investigated in the pedagogical supervision. The efficiency of actions in attack of diagonal players of women's teams of Student's ...

  18. Increase of productivity attacks of young basketbal players on the basis perfection their competitive activity.

    Directory of Open Access Journals (Sweden)

    Kozin V.V.

    2011-02-01

    Full Text Available Research objective is increase of productivity attacks of basketball players 15-17 years on the basis perfection their competitive activity creation of situations of counteractions is carried out by connection of models in the directed programming system of game activity. The system has different character and allows to model individual and group counteractions. The gain of indicators of mental qualities is as a result established, increase of indicators of force and speed qualities, productivity of attacking actions is noted.

  19. Prevention of Co-operative Black Hole attack in Manet on DSR protocol using Cryptographic Algorithm

    Directory of Open Access Journals (Sweden)

    G.Vennila

    2014-10-01

    Full Text Available The Mobile ad-hoc network (MANET is a collection of wireless mobile node in which each node can communicate with other node without use of predefined infrastructure. Currently, a lot of efficient protocols have been proposed for MANET. All of these efficient Routing protocols are depends only conviction and supportive environment. Conversely, the networks are more vulnerable to various kinds of routing attacks with the presence of malicious nodes. Black hole attack is one of network layer attack. In this attack, A malicious node make use of routing protocol to advertise itself that has a shortest path to reach destination, drops at the cost of original routing packets. In our work, the proposed algorithm is used to secure the DSR protocol. This will help to improve the performance of Mobile Ad hoc network due to the attack. There are several prevention mechanisms to eliminate the Black Hole attack in MANET. The aim of the paper is to provide better prevention of Co-operative Black hole attack in MANET and how it affects the performance metrics in terms of throughput and delay of the network by comparing the network performance with and without black hole nodes.

  20. The robustness of multiplex networks under layer node-based attack

    Science.gov (United States)

    Zhao, Da-Wei; Wang, Lian-Hai; Zhi, Yong-Feng; Zhang, Jun; Wang, Zhen

    2016-04-01

    From transportation networks to complex infrastructures, and to social and economic networks, a large variety of systems can be described in terms of multiplex networks formed by a set of nodes interacting through different network layers. Network robustness, as one of the most successful application areas of complex networks, has attracted great interest in a myriad of research realms. In this regard, how multiplex networks respond to potential attack is still an open issue. Here we study the robustness of multiplex networks under layer node-based random or targeted attack, which means that nodes just suffer attacks in a given layer yet no additional influence to their connections beyond this layer. A theoretical analysis framework is proposed to calculate the critical threshold and the size of giant component of multiplex networks when nodes are removed randomly or intentionally. Via numerous simulations, it is unveiled that the theoretical method can accurately predict the threshold and the size of giant component, irrespective of attack strategies. Moreover, we also compare the robustness of multiplex networks under multiplex node-based attack and layer node-based attack, and find that layer node-based attack makes multiplex networks more vulnerable, regardless of average degree and underlying topology.

  1. [Risk perception and psychological reactions in public crisis situations using the example of terror attacks].

    Science.gov (United States)

    Grimm, A; Hulse, L; Schmidt, S

    2009-12-01

    The reactions to the 9/11 terror attacks were immense in the western population. In the current review, the impact of terror attacks is presented with surveys, clinical interviews, and scientific polls, which were identified in a comprehensive literature search. Results show that the fear of further terror attacks is comparatively overestimated in the population and is associated with numerous psychological consequences and reactions. The overestimation of the probability of further terror attacks is related among other reasons to its unique features and its strong representation in the media. Several independent studies proved that the number of stress symptoms and psychiatric diagnoses is associated with a high risk perception in relation to terror attacks. This was not only the case for victims of terror attacks, but also for people indirectly exposed to the terror attacks. In addition, there is evidence that the number of the stress symptoms correlate with the duration of TV consumption of new findings about terror attempts. Methodologically, there is a critical lack of more in-depth analyses to explain the development of risk perceptions and its influence on mental and physical health. Because of the international importance and cross-cultural differences, an international standardization of research is desirable. PMID:19862488

  2. Distribution of angles in hyperbolic lattices

    DEFF Research Database (Denmark)

    Risager, Morten Skarsholm; Truelsen, Jimi Lee

    2010-01-01

    We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result from the study by Boca.......We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result from the study by Boca....

  3. Distribution of Angles in Hyperbolic Lattices

    DEFF Research Database (Denmark)

    S. Risager, Morten; L. Truelsen, Jimi

    2008-01-01

    We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result due to F. P. Boca.......We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result due to F. P. Boca....

  4. Efficiency of actions in attack of diagonal players in female volleyball

    Directory of Open Access Journals (Sweden)

    Yevgeniya Strelnykova

    2016-04-01

    Full Text Available Purpose: to define efficiency of technical and tactical actions of the diagonal player in the attacking actions of a team depending on schemes of a defensive play of the rival. Material & Methods: the competitive process with participation of 10 players of the role –the diagonal forward of qualification and the adult category was investigated in the pedagogical supervision. The efficiency of actions in attack of diagonal players of women's teams of Student's volleyball league of Kharkov was defined by mathematical processing of the obtained data. Results: we carried out the analysis of references on a condition of a problem of training of the diagonal player, defined tactical combinations in attack in which the diagonal player and efficiency of game actions of the diagonal player take part in the attacking actions of women's teams of Student's volleyball league of Kharkov defining indicators of efficiency of technical and tactical actions of the diagonal player in the attacking actions of women's teams of Student's league of Kharkov against various schemes of a defensive play of teams of the rival. Conclusions: the offered methodical approach based on a quantitative assessment of the competitive activity will allow to rationalize the structure and distribution of means of trainings and to increase the efficiency of the whole educational and training process of training of diagonal players for a game in attack against teams which build a defensive play according to various schemes.

  5. An Efficient Algorithm for the Detection of Exposed and Hidden Wormhole Attack

    Directory of Open Access Journals (Sweden)

    ZUBAIR AHMED KHAN

    2016-07-01

    Full Text Available MANETs (Mobile Ad Hoc Networks are slowly integrating into our everyday lives, their most prominent uses are visible in the disaster and war struck areas where physical infrastructure is almost impossible or very hard to build. MANETs like other networks are facing the threat of malicious users and their activities. A number of attacks have been identified but the most severe of them is the wormhole attack which has the ability to succeed even in case of encrypted traffic and secure networks. Once wormhole is launched successfully, the severity increases by the fact that attackers can launch other attacks too. This paper presents a comprehensive algorithm for the detection of exposed as well as hidden wormhole attack while keeping the detection rate to maximum and at the same reducing false alarms. The algorithm does not require any extra hardware, time synchronization or any special type of nodes. The architecture consists of the combination of Routing Table, RTT (Round Trip Time and RSSI (Received Signal Strength Indicator for comprehensive detection of wormhole attack. The proposed technique is robust, light weight, has low resource requirements and provides real-time detection against the wormhole attack. Simulation results show that the algorithm is able to provide a higher detection rate, packet delivery ratio, negligible false alarms and is also better in terms of Ease of Implementation, Detection Accuracy/ Speed and processing overhead.

  6. Intrinsic and External Factors and Influences on the Motivation of Suicide Attackers

    Directory of Open Access Journals (Sweden)

    Gregor Bruce

    2013-09-01

    Full Text Available Suicide terrorism is the most extreme example of asymmetrical warfare. It is dramatic, frightening and can be very effective for the terrorist group which employs it. The psychological effects are out of proportion to the damage caused. The individual attackers have a mixture of motivations and the combination of motivators varies between the individual attackers, their groups and their causes. The terms “suicide terrorism”, “suicide attacks”, “suicide missions” and “suicide bombing” have specific meanings. Pape (1 limits the term “suicide attack” to an attack which is only successful with the death of the terrorist. The terrorist deploys in the expectation of certain death to ensure the success of the mission. “Suicide bombers”are a specific example of this genre as are hijackers who fly aircraft into buildings. “Suicide missions” are carried out by terrorists who realistically do not expect to survive the mission and do not have an escape plan but sometimes survive. The success of the mission is not dependent on their death. Examples are the 1972 attack on Lod Airport and the 2008 attack on Mumbai. “Suicide terrorism” is an all-embracing term that covers all of these events. Participants in suicide attacks have significant differences in their aims, psychological profiles and motivation from those who participate in suicide missions. This paper is specifically directed to the motivation of suicide attackers.

  7. Angle-independent structural colors of silicon

    DEFF Research Database (Denmark)

    Højlund-Nielsen, Emil; Weirich, Johannes; Nørregaard, Jesper;

    2014-01-01

    Structural colors are optical phenomena of physical origin, where microscale and nanoscale structures determine the reflected spectrum of light. Artificial structural colors have been realized within recent years. However, multilayer structures require substantial fabrication. Instead we considered...... one-layer surface textures of silicon.We explored four patterns of square structures in a square lattice with periods of 500, 400, 300, and 200 nm. The reflectivity and daylight-colors were measured and compared with simulations based on rigorously coupledwave analysis with excellent agreement. Based...... on the 200-nm periodic pattern, it was found that angle-independent specular colors up to 60 deg of incidence may be provided. The underlying mechanisms include (1) the suppression of diffraction and (2) a strong coupling of light to localized surface states. The strong coupling yields absorption...

  8. Before Using Aspirin to Lower Your Risk of Heart Attack or Stroke, Here Is What You Should Know

    Science.gov (United States)

    ... Medicines Safe Daily Use of Aspirin Before Using Aspirin to Lower Your Risk of Heart Attack or ... care provider can determine whether regular use of aspirin will help to prevent a heart attack or ...

  9. Denial of Service Attack: Analysis of Network Traffic Anormaly using Queuing Theory

    CERN Document Server

    Singh, Neetu; Chaudhuri, Pranay

    2010-01-01

    Denial-of-service (DOS) attacks increasingly gained reputation over the past few years. As the Internet becomes more ubiquitous, the threat of the denial-of-service attacks becomes more realistic and important for individuals, businesses, governmental organizations, and even countries. There is intensive need to detect an attack in progress as soon as possible. The efficiency of diagnosing the DOS attack using concepts of queuing theory and performance parameter of the system has been investigated in the present work, as the servers definitely have some mechanisms to store and process the requests. Utilizing this concept of queuing theory, the collection of data patterns were generated. With the performance parameter of the system, the analysis of the data pattern had been made to diagnose the network anomaly. Performance analysis and results show the accuracy of the proposed scheme in detecting anomalies.

  10. Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways

    Institute of Scientific and Technical Information of China (English)

    Antonio Giovino; Federico Martinelli; Sergio Saia

    2016-01-01

    The red palm weevil (RPW; Rhynchophorus ferrugi-neus) is spreading worldwide and severely harming many palm species. However, most studies on RPW focused on insect biology, and little information is available about the plant response to the attack. In the present experiment, we used metabolomics to study the alteration of the leaf metabolome of Phoenix canariensis at initial (1st stage) or advanced (2nd stage) attack by RPW compared with healthy (unattacked) plants. The leaf metabolome significantly varied among treatments. At the 1st stage of attack, plants showed a reprogramming of carbohydrate and organic acid metabolism;in contrast, peptides and lipid metabolic pathways underwent more changes during the 2nd than 1st stage of attack. Enrichment metabolomics analysis indicated that RPW attack mostly affected a particular group of compounds rather than rearranging plant metabolic pathways. Some compounds selectively affected during the 1st rather than 2nd stage (e.g. phenylalanine;tryptophan;cel obiose;xylose;quinate;xylonite;idonate;and iso-threonate;cel obiotol and arbutine) are upstream events in the phenylpropanoid, terpenoid and alkaloid biosynthesis. These compounds could be designated as potential markers of initial RPW attack. However, further investigation is needed to determine efficient early screening methods of RPW attack based on the concentrations of these molecules.

  11. On the effectiveness of XML schema validation for countering XML signature wrapping attacks

    DEFF Research Database (Denmark)

    Jensen, Meiko; Meyer, Christopher; Somorovsky, Juraj;

    2011-01-01

    In the context of security of Web Services, the XML Signature Wrapping attack technique has lately received increasing attention. Following a broad range of real-world exploits, general interest in applicable countermeasures rises. However, few approaches for countering these attacks have been...... investigated closely enough to make any claims about their effectiveness. In this paper, we analyze the effectiveness of the specific countermeasure of XML Schema validation in terms of fending Signature Wrapping attacks. We investigate the problems of XML Schema validation for Web Services messages...

  12. Handbook of biometric anti-spoofing trusted biometrics under spoofing attacks

    CERN Document Server

    Marcel, Sébastien; Li, Stan Z

    2014-01-01

    As the plethora of approaches to biometrics and their deployment continues to grow, so too does the need to combat the techniques used to subvert the aim of such biometric systems. Presenting the first definitive study of the subject, this Handbook of Biometric Anti-Spoofing reviews the state of the art in covert attacks against biometric systems, and in deriving countermeasures to these attacks. Across a range of common biometrics, including face, iris, fingerprint, speaker and gait, the book describes spoofing methods and examines the vulnerabilities of biometric systems to these attacks.

  13. Detection and Avoidance of SQL Injection Attack In Multi-Tier Web Based Application

    Directory of Open Access Journals (Sweden)

    Ms. S.Raichal

    2013-06-01

    Full Text Available The aim of this paper is to prevent sql injection attack using stored procedure. In SQL injection attack,an attacker might deliver malicious SQL query segments as user input which could effect in a different database request. Using SQL injection attacks, an attacker might thus obtain and modify confidential information. An attacker could even use a SQL injection vulnerability as a basic IP or Port scanner of the internal corporate network. The stored procedure does not permit conditional statement there by the hacker cannot identify the IDs. The stored procedure is the new approach that is executed. Stored procedure avoids the attack which is more secured one where the conditional statements are not permitted. In sql injection input is set as conditional statements and the user can able to login into the website. But in this paper every condition are checked in the procedural language of stored procedure.Once it notices the condition statement the user will be blocked to log into the website. Only the correct form of passwords is acceptable.

  14. Resistance of Some Timbers of Andhra Pradesh Against Marine Borer Attack at Four Ports on India

    Directory of Open Access Journals (Sweden)

    N. Kalyanasundaram

    1974-07-01

    Full Text Available Observations on the underwater durability of thirteen species of times growth in Andhra Pradesh against marine borer attack at four ports of Naval interest are recorded. Intensity of borer attack was found to vary from port to port, maximum observed being at Port Blair, with Goa, Bombay and Visakhapatnam following in that order. Comparison of borer activity in the harbours studies with past observations has revealed that a change in eco-systems may be occurring at Visakhapatnam harbour.

  15. The association between abdominal obesity and characteristics of migraine attacks in Iranian adults

    Science.gov (United States)

    Sadeghi, Omid; Askari, Gholamreza; Maghsoudi, Zahra; Ghiasvand, Reza; Khorvash, Fariborz

    2016-01-01

    Background: Migraine is a primary headache disorder that affects the neurovascular system. Recent studies have shown that migraine patients with general obesity have higher characteristics of migraine attacks compared with normal weight patients, but data on central obesity are scarce. This study was done to assess the relationship between central obesity and the characteristics of migraine attacks in migraine patients. Materials and Methods: This cross-sectional study was conducted on 129 migraine patients (28 men and 101 women), aged 15–67 years, in Isfahan, Iran. Anthropometric measurements such as waist circumference (WC), hip circumference (HC), waist–hip ratio (WHR) and waist–height ratio (WHtR), as well as characteristics of migraine attacks such as severity, frequency, duration, and headache diary result (HDR) was determined for each participant. Linear regression was used to examine the association between anthropometric measurements and characteristics of migraine attacks. P value less than 0.05 was considered significant. Results: WC, WHR, and WHtR were positively associated with the severity (P-value: WC: 0.002, WHR: 0.002, WHtR: 0.001) and frequency (P-value: WC: 0.006, WHR: 0.01, WHtR: 0.002) of migraine attacks. Moreover, we found a significant association between WC (P = 0.001), WHR (P = 0.004), and WHtR (P < 0.001) with HDR. No significant relationship was observed between central obesity indicators and duration of migraine attacks. Conclusions: Central obesity indicators were positively associated with the severity and frequency of migraine attacks as well as HDR, but not with duration of attacks. Based on our findings, it can be concluded that weight loss may decrease the characteristics of migraine attacks.

  16. The Relationships Between Weather and Climate and Attacks of Bronchitis

    Science.gov (United States)

    Talaia, M. A. R.; Saraiva, M. A. C.; Vieira da Cruz, A. A.

    The area of Aveiro, more concretely Aveiro lagoon, a natural laboratory has been con- sidered, for promoting the development and the application of several investigations worked. The importance of the influences of weather and climate on human health has been well known since ancient teams and many decisions concerning human be- haviour it are clearly weather related. However, decisions related to weather criteria can be important and economically significant, but the real economic effect of the weather is difficult to assess. Talaia et al. (2000) and Talaia and Vieira da Cruz (2001) have shown the possible harmful effect of certain meteorological factors on respiratory conditions. Bronchitis is a disease caused by inflammation of the bronchi as a result of infectious agents or air pollutants. In this study our attention is to relate, the be- ginning of bronchitis attacks in the services of urgency of the Hospital of Aveiro with meteorological factors, and the risk group are studied. We used the medical records and the database of meteorological factors. The obtained analysis allows to conclude that some meteorological factors have correlation with the occurrences of the disease and to allow improving the work in the urgency services in the requested periods. The knowledge that will be extracted of this study can be used later in studies that inte- grate other important components for the characterisation of the environmental impact in the area. References: Talaia, M.A.R., Vieira da Cruz, A.A., Saraiva, M.A.C., Amaro, G.S., Oliveira, C.J. and Carvalho, C.F., 2000, The Influence of Meteorological Fac- tors on Pneumonia Emergencies in Aveiro, International Symposium on Human- Biometeorology, St. Petersburg (Pushkin), Russia, pp. 67-68. Talaia, M.A.R. and Vieira of Cruz, A.A., (2001), Meteorological Effects on the Resistance of the Body to Influenza - One Study in Aveiro Region, Proceedings 2nd Symposium of Meteorol- ogy and Geophysics of APMG and 3rd Meeting

  17. DETECTION AND LOCALIZATION OF MULTIPLE SPOOFING ATTACKERS FOR MOBILE WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    R. Maivizhi

    2015-06-01

    Full Text Available The openness nature of wireless networks allows adversaries to easily launch variety of spoofing attacks and causes havoc in network performance. Recent approaches used Received Signal Strength (RSS traces, which only detect spoofing attacks in mobile wireless networks. However, it is not always desirable to use these methods as RSS values fluctuate significantly over time due to distance, noise and interference. In this paper, we discusses a novel approach, Mobile spOofing attack DEtection and Localization in WIireless Networks (MODELWIN system, which exploits location information about nodes to detect identity-based spoofing attacks in mobile wireless networks. Also, this approach determines the number of attackers who used the same node identity to masquerade as legitimate device. Moreover, multiple adversaries can be localized accurately. By eliminating attackers the proposed system enhances network performance. We have evaluated our technique through simulation using an 802.11 (WiFi network and an 802.15.4 (Zigbee networks. The results prove that MODELWIN can detect spoofing attacks with a very high detection rate and localize adversaries accurately.

  18. Childhood Internalizing and Externalizing Problems Predict the Onset of Clinical Panic Attacks over Adolescence: The TRAILS Study

    OpenAIRE

    Mathyssek, Christina M.; Olino, Thomas M.; Verhulst, Frank C.; Oort, Floor V. A.

    2012-01-01

    textabstractBackground: Panic attacks are a source of individual suffering and are an independent risk factor for later psychopathology. However, much less is known about risk factors for the development of panic attacks, particularly during adolescence when the incidence of panic attacks increases dramatically. We examined whether internalizing and externalizing problems in childhood predict the onset of panic attacks in adolescence. Method: This study is part of the TRacking Adolescents' In...

  19. Investigation of digestion Kinetics in commercial starches using in-situ small-angle neutron scattering

    International Nuclear Information System (INIS)

    Full text: The digestion of starch has been the subject of many investigations, mostly involving in vitro measurement of the susceptibility of starches to attack by different enzymes, rather than measuring actual digestibility in vivo. The rate and extent of amylolytic hydrolysis of granular starches is known to vary according to botanical origin. Granule characteristics considered to influence susceptibility to attack by alpha-amylase include crystallinity, granule size and available specific surface, amylose content, porosity, structural inhomogeneities and degree of integrity. Most in-vitro studies of granular starch digestion have been limited to samples for which aliquots have been removed from the reaction mixture at various time intervals and freeze-dried to be subsequently characterized using a range of techniques. It remains unclear whether sample preparation creates artefacts in the samples. In this study, we have studied the kinetics of starch digestion of several commercial granular starches by time-resolved small-angle neutron scattering using an in-situ digestion chamber allowing, for the first time, to follow structural changes of starch in the course of digestion directly in the digestion mixture. Additionally, samples before and after digestion were studied by x-ray diffraction, small-angle x-ray scattering, differential scanning calorimetry and microscopy. Microscopy revealed that studied starches, which varied in their amylose content and digestion kinetics, followed different modes of attack The multidisciplinary approach allowed the nanostructural changes detected by small-angle scattering in the course of enzymic breakdown to be correlated with changes in crystallinity and functional properties.

  20. Cycles of violence, and terrorist attacks index for the State of Oklahoma

    OpenAIRE

    Gómez-sorzano, Gustavo

    2007-01-01

    I apply the Beveridge-Nelson business cycle decomposition method to the time series of per capita murder of Florida State (1933-2005). Separating out “permanent” from “cyclical” murder, I hypothesize that the cyclical part coincide with documented waves of organized crime, internal tensions, crime legislation, social, and political unrest, and with the periodic terrorist attacks to the U.S. The estimated cyclical component of murder shows that terrorist attacks against the U.S. have affecte...

  1. Cycles of violence, and terrorist attacks index for the State of Ohio

    OpenAIRE

    Gómez-sorzano, Gustavo

    2006-01-01

    I apply the Beveridge-Nelson business cycle decomposition method to the time series of per capita murder in the State of Ohio. (1933-2005). Separating out “permanent” from “cyclical” murder, I hypothesize that the cyclical part coincides with documented waves of organized crime, internal tensions, crime legislation, social, and political unrest, and recently with the periodic terrorist attacks to the U.S. The estimated cyclical component of murder warns that terrorist attacks against the U....

  2. The dynamic correlation between degree and betweenness of complex network under attack

    Science.gov (United States)

    Nie, Tingyuan; Guo, Zheng; Zhao, Kun; Lu, Zhe-Ming

    2016-09-01

    Complex networks are often subjected to failure and attack. Recent work has addressed the resilience of complex networks to either random or intentional deletion of nodes or links. Here we simulate the breakdown of the small-world network and the scale-free network under node failure or attacks. We analyze and discuss the dynamic correlation between degree and betweenness in the process of attack. The simulation results show that the correlation for scale-free network obeys a power law distribution until the network collapses, while it represents irregularly for small-world network.

  3. Novel Psychological Formulation and Treatment of "Tic Attacks" in Tourette Syndrome.

    Science.gov (United States)

    Robinson, Sally; Hedderly, Tammy

    2016-01-01

    One important, but underreported, phenomenon in Tourette syndrome (TS) is the occurrence of "tic attacks." These episodes have been described at conferences as sudden bouts of tics and/or functional tic-like movements, lasting from 15 min to several hours. They have also been described by patients in online TS communities. To date, there are no reports of tic attacks in the literature. The aim of this article is to stimulate discussion and inform clinical practices by describing the clinical presentation of 12 children (mean age 11 years and 3 months; SD = 2 years and 4 months) with TS and tic attacks, with a detailed case report for one case (13-year-old male). These children commonly present acutely to casualty departments and undergo unnecessary medical investigations. Interestingly, all children reported comorbid anxiety, with worries about the tics themselves and an increased internal focus of attention on tics once the attacks had started. In keeping with other children, the index case reported a strong internal focus of attention, with a relationship between physiological sensations/tic urges, worries about having tic attacks, and behavioral responses (e.g., body scanning, situational avoidance, and other responses). In our experience, the attacks reduce with psychological therapy, for example, the index case attended 13 sessions of therapy that included metacognitive and attention training techniques, as well as cognitive-behavioral strategies. Following treatment, an improvement was seen across a range of measures assessing tics, mood, anxiety, and quality of life. Thus, psychological techniques used to treat anxiety disorders are effective at supporting a reduction in tic attacks through modifying attention, worry processes, and negative beliefs. It is hypothesized that an attentional style of threat monitoring, difficulties tolerating internal sensory urges, cognitive misattributions, and maladaptive coping strategies contribute to the

  4. Knowledge of Signs and Symptoms of Heart Attack and Stroke among Singapore Residents

    Directory of Open Access Journals (Sweden)

    Joy Li Juan Quah

    2014-01-01

    Full Text Available Aim. To determine the level of knowledge of signs and symptoms of heart attack and stroke in Singapore resident population, in comparison to the global community. Methods. A population based, random sample of 7,840 household addresses was selected from a validated national sampling frame. Each participant was asked eight questions on signs and symptoms of heart attack and 10 questions on stroke. Results. The response rate was 65.2% with 4,192 respondents. The level of knowledge for preselected, common signs and symptoms of heart attack and stroke was 57.8% and 57.1%, respectively. The respondents scored a mean of 5.0 (SD 2.4 out of 8 for heart attack, while they scored a mean of 6.8 (SD 2.9 out of 10 for stroke. Respondents who were ≥50 years, with lower educational level, and unemployed/retired had the least knowledge about both conditions. The level of knowledge of signs and symptoms of heart attack and stroke in Singapore is comparable to USA and Canada. Conclusion. We found a comparable knowledge of stroke and heart attack signs and symptoms in the community to countries within the same economic, educational, and healthcare strata. However older persons, those with lower educational level and those who are unemployed/retired, require more public health education efforts.

  5. Dynamic global games of regime change: Learning, multiplicity, and timing of attacks

    OpenAIRE

    Angeletos, George-Marios; Hellwig, Christian; Pavan, Alessandro

    2006-01-01

    Global games of regime change-coordination games of incomplete information in which a status quo is abandoned once a sufficiently large fraction of agents attacks it-have been used to study crises phenomena such as currency attacks, bank runs, debt crises, and political change. We extend the static benchmark examined in the literature by allowing agents to take actions in many periods and to learn about the underlying fundamentals over time. We first provide a simple recursive algorithm for t...

  6. The Weight of Cognitions in Panic: The Link between Misinterpretations and Panic Attacks

    OpenAIRE

    Klara De Cort; Dirk Hermans; Daphne Noortman; Wiesje Arends; Griez, Eric J. L.; Schruers, Koen R. J.

    2013-01-01

    In cognitive theory it is hypothesized that panic attacks are provoked by catastrophic misinterpretations of bodily sensations. The aim of the present study was to investigate the ability of associated word pairs referring to catastrophic thinking (e.g. palpitations-heart attack) in producing panic attacks. Patients with PD (n = 20), patients with mixed anxiety disorders (n = 20), and a healthy control group (n = 30) participated in the present study. To enhance ecological validity we first c...

  7. Integrated Hidden Markov Model and Bayes Packet Classifier for effective Mitigation of Application DDoS attacks

    OpenAIRE

    Prabha, S.; R Anitha

    2011-01-01

    Resisting distributed denial of service (DDoS) attacks become more challenging with the availability of resources and techniques to attackers. The application-layer-based DDoS attacks utilize legitimate HTTP requests to overwhelm victim resources are more undetectable and are protocol compliant and non-intrusive. Focusing on the detection for application layer DDoS attacks, the existing scheme provide an access matrix which capture the spatial-temporal patterns of a normal flash crowd on non ...

  8. Evaluation of Detection System of Fault Attacks based on Neural Network into a Java Virtual Machine

    Directory of Open Access Journals (Sweden)

    Ilhame El farissi

    2013-08-01

    Full Text Available The Java Card technology provides a secure environment for developing smart card application based on Java while also respecting some constraints such as the limited memory and processing card. In addition to the security and cryptography APIs offered by the Java Card technology, the smart card is protected against some threats. But, the fault attacks based on the variation of the physical parameters are able to disrupt its operation. In order to enhance the smart card security, we thought to add an intelligent component able to distinguish between the smooth functioning and the attack. This component is a Neural Network that we developed in C language and integrated in open source Virtual Machine (Avian in order to simulate the attack effect and the network behavior. In this context, the detection rate of the attacks is 96% with no false positive.

  9. Regulation of regional cerebral blood flow during and between migraine attacks

    DEFF Research Database (Denmark)

    Lauritzen, M; Olsen, T S; Lassen, N A; Paulson, O B

    1983-01-01

    254 areas of one hemisphere. The partly hypoperfused hemisphere allowed for comparison of adjacent hypoperfused and normally perfused brain areas. During attacks the carbon dioxide reactivity was decreased to 2.8 +/- 0.8% per mm Hg in the oligemic regions compared with 5.8 +/- 0.8% per mm Hg in the......Cerebrovascular reactivity to voluntary hyperventilation, moderate hypertension, and physiological activation was studied in nine patients during induced migraine attacks and in four patients between their attacks. Regional cerebral blood flow was measured by the xenon 133 injection technique in...

  10. French Ministry of Health's response to Paris attacks of 13 November 2015.

    Science.gov (United States)

    Philippe, Jean-Marc; Brahic, Olivier; Carli, Pierre; Tourtier, Jean-Pierre; Riou, Bruno; Vallet, Benoit

    2016-01-01

    On Friday November 13th at 9:20 pm, three kamikaze bombs went off around the Stade de France a stadium in Saint-Denis just outside Paris, 4 different shootings took place and bombings in Paris and hundreds of people were held hostage in a theater.This multi-site terrorist attack was the first of this magnitude in France. Drawing the lessons of these attacks and those which occurred in other countries from a health perspective is essential to continuously adapt and improve the French response to possible future attacks.Several issues would need to be further explored: Management of uncertainties: When to trigger the plans: after the 1st attack, the 2nd? When do attacks end and when to release mobilized resources? Management of victims: How to ensure that all victims are secured or taken care of? How to provide assistance when attacks are ongoing? Management of teams: Proper follow-up of persons involved in the response: health professionals, police and firemen, emergency call centers but also civil servants within administration that contributed to the response. Communication: Reactivity of all is a key element to secure appropriate resource is mobilized for the response. All actors have to be able to communicate quickly in a secured way. PMID:27039082

  11. Childhood Internalizing and Externalizing Problems Predict the Onset of Clinical Panic Attacks over Adolescence: The TRAILS Study

    NARCIS (Netherlands)

    C.M. Mathyssek (Christina); T.M. Olino (Thomas); F.C. Verhulst (Frank); F.V.A. van Oort (Floor)

    2012-01-01

    textabstractBackground: Panic attacks are a source of individual suffering and are an independent risk factor for later psychopathology. However, much less is known about risk factors for the development of panic attacks, particularly during adolescence when the incidence of panic attacks increases

  12. Attack behavior of Podisus rostralis (Heteroptera: Pentatomidade adults on caterpillars of Bombyx mori (Lepidoptera: Bombycidae

    Directory of Open Access Journals (Sweden)

    Walkymário Paulo Lemos

    2005-11-01

    Full Text Available Attack behavior of the predator Podisus rostralis (Stäl (Heteroptera: Pentatomidae adults on fourth instar Bombyx mori L. (Lepidoptera: Bombycidae caterpillars was studied in laboratory conditions. Ten 24 hours old adults of this predator were observed during two hours with the following attack behavior: (1 Predator: prey finding; prey observation; touching prey with antenna; attack behavior; prey paralysis; predator retreat after attack; attack cessation; successive attacks; and (2 Prey: defense. The predator P. rostralis found its prey before attacking and it approached it with slow circular movements. The attack was usually made in the posterior part of the prey to reduce defense reaction. Larger size of prey in relation to the predator resulted difficult prey paralysis but it occurred in less than two hours.Estudou-se, em laboratório, o comportamento de ataque de adultos do predador Podisus rostralis (Stäl (Heteroptera: Pentatomidae tendo como presa lagartas de quarto estádio de Bombyx mori L. (Lepidoptera: Bombycidae. Dez adultos do predador, com 24 horas de idade, foram observados durante duas horas acompanhando-se os seguintes comportamentos de ataque: (1 Predador: localização da presa; observação da presa; toque das presas com as antenas; comportamento de ataque; paralisação da presa; fuga do predador após ataque; finalização do ataque; ataques sucessivos; e (2 Presa: defesa. O predador P. rostralis localizou sua presa antes do ataque, aproximando-se dela através de lentos movimentos circulares. O ataque é, usualmente, realizado na parte posterior da presa para reduzir reação de defesa. O maior tamanho da presa em relação ao predador pode dificultar a paralisação, porém o predador consegue paralisá-la em menos de duas horas.

  13. A Comparitive Study of the Available Solutions to Minimize Denial of Service Attacks in Wireless LAN

    Directory of Open Access Journals (Sweden)

    Arockiam .L

    2011-05-01

    Full Text Available Denial of Service (DoS attack is a major attack in Wireless Local Area Network. This paper studies the available solutions for Denial of Service (DoS attacks and compares them with each other in a wireless infrastructure network. All these methods are used to minimize the DoS attacks. It discusses the Central Manager (CM, Medium Access Control Address Filtering (MAF and Traffic Pattern Filtering (TPF methods to avoid DoS attacks in Wireless Local Area Network (WLAN. Central Manager (CM provides the better solution to avoid DoS attacks and it improves the performance of WLAN with the help of tables and timer. In the case of Transmission Control Protocol (TCP, MAF and TPF methods are used to detect and resolve Authentication Request Flooding (AuthRF and Association Request Flooding (AssRF. This paper compares the performance of these two solutions based on throughput and the results are analyzed with the graphs.

  14. Temperature Influence on Divergence Angles of Quartz Crystal Wollaston Prism

    International Nuclear Information System (INIS)

    We propose a structural angle and main refractive indices as two key factors to understand the temperature influence on the divergence angles of the Wollaston prism. The temperature influence on the divergence angles of quartz crystal Wollaston prism is studied theoretically The results show that divergence angles decrease with increasing temperature, while the divergence angle of e-light decrease more quickly than that of o-light. The testing system is established to verify the above results, and the experimental results are in agreement well with the theoretical analysis. (fundamental areas of phenomenology (including applications))

  15. Determination of the angle of attack on the mexico rotor using experimental data

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær;

    2010-01-01

    characteristics from experimental data on the MEXICO (Model Experiments in controlled Conditions) rotor. Detailed surface pressure and Particle Image Velocimetry (PIV) flow field at different rotor azimuth positions were examined for determining the sectional airfoil data. It is worthwhile noting that the present...

  16. Helicobacter pylori infection as a triggering factor of attacks in patients with hereditary angioedema

    DEFF Research Database (Denmark)

    Visy, Beáta; Füst, George; Bygum, Anette;

    2007-01-01

    BACKGROUND: Helicobacter pylori infection is considered among the causative factors of urticaria and angioedema. Having conducted a study on 65 patients, Hungarian authors reported in 2001 that successful eradication of H. pylori is followed by a significant reduction in the number of attacks in...... (> or = 5 per year) abdominal attacks was higher (p = .002) among the H. pylori-infected participants of the international study who underwent eradication as compared to the rest of patients. Successful eradication of H. pylori significantly (p = .0006) reduced the number of attacks in these patients as...... of frequent, edematous abdominal attacks may decrease substantially following the eradication of H. pylori from HAE patients infected with this pathogen. Therefore, screening of patients with HAE for H. pylori infection seems warranted. Eradication of H. pylori may lead to a marked reduction in...

  17. Concrete durability: physical chemistry of the water attack

    International Nuclear Information System (INIS)

    Cement paste constitutes an basic medium, thermodynamically stable for high pH's. For this reason, water constitutes an aggressive environment. For hydraulic structures, or nuclear waste disposal, water must be considered as a 'chemical loading'. In the short- and medium-term water-degradation of cement paste is principally due to transport of matter between the healthy zone and the aggressive solution through diffusion of ionic species from the interstitial solution of the cement paste. In the long-term, dissolution of the surface may occur. Various cement pastes were prepared and leached with continually demineralized water. After a critical time, which depends on the type of paste, the dissolution of the surface layer in contact with water will control the degradation kinetics. The diffusive and chemical properties of the degraded layer are therefore fundamental for the prediction of the long-term behaviour of concrete in water. 29Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) combined with 27A1 MAS NMR and 57Fe Moessbauer spectroscopy indicate that the superficial layer is formed by a CSH with a molecular structure near from the tobermorite mineral. Nuclear magnetic resonance techniques allow us to demonstrate the fundamental role of cationic substitutions occurring in the CSH during degradation on the superficial layer solubility. Our experimental results were used to model the cement paste behaviour taking into account the diffusion and the dissolution of the material. (author)

  18. Monitoring of sulphate attack on hardened cement paste studied by synchrotron XRD

    Science.gov (United States)

    Stroh, J.; Meng, B.; Emmerling, F.

    2015-10-01

    The complex matter of external sulphate attack on cement-based construction materials is still not completely understood. The concentration of sulphate is a crucial factor for the formation of secondary phases and phase transitions of cement hydrates due to sulphate ingress into the microstructure. The sulphate attack on building materials for high and low sulphate concentrations was monitored by laboratory experiments. Hardened cement paste consisting of ordinary Portland cement (CEM I) were exposed to aqueous solutions of sodium sulphate for 18 months. Three sample compositions were used for this research, including different supplementary cementitious materials (SCM). The phase composition was determined for different time spans by high resolution synchrotron X-ray diffraction. Cross sections of exposed cement prisms were investigated as a representation of the microstructural profile. Based on the data, a temporal and spatial determination of the stages of the sulphate attack and the deterioration course was possible. Cement matrices blended with slag showed the highest resistance against sulphate attack.

  19. A Review: Durability of Fired Clay Brick Masonry Wall due to Salt Attack

    Directory of Open Access Journals (Sweden)

    B.H. Abu Bakar

    2009-12-01

    Full Text Available This paper offers a review on durability of fired clay brick masonry wall due to salt attack. Durability of brick normally affected when an external masonry walls are exposed to aggressive environment. Masonry structures, when subjected to salt attack or exposed to aggressive environment during their service life may suffer degradation due to the formation of crystallization pressure as a result of the evaporation of soluble salt in clay masonry structures. The crystallization pressures produce normally higher than tensile stress of clay brick and sufficient to damage the masonry structures. The mechanism of salt attack must be prevented and addressed thoroughly in order to maintain the integrity and service life of masonry wall. Therefore, the summary of durability, factors, mechanism and main sources of salt attack on fired clay brick masonry walls are discussed.

  20. HEALING OF HYDROGEN ATTACK CRACK IN AUSTENITE STAINLESS STEEL UNDER HEAT TREATMENT

    Institute of Scientific and Technical Information of China (English)

    X.G. Li; C.F. Dong; H. Chen

    2002-01-01

    The specimens of 304 austenite stainless steel with the hydrogen attack bubbles orcracks were heat treated at 600℃ for 6h. The SEM and TEM observations on thespecimens before and after the heat treatment showed that the bubbles or cracks could behealed completely by heat treatment. The healing of hydrogen attack bubbles or cracksis closely related to heat diffusion of Fe and C atoms in austenite. The driving forceof crack healing results fram the plastic deforming energy Es induced by the growthof hydrogen attack bubbles or cracks. The critical condition of healing of bubbles orcracks is Es ≥ 2γ/r (where γγ is the surface tension, r is the radius of bubbles or halflength of crack). During healing of the hydrogen attack bubbles or cracks, the recovery,polygonization and recrystallization of the sub-grain also occured.

  1. Aspirin for Reducing Your Risk of Heart Attack and Stroke: Know the Facts

    Science.gov (United States)

    ... the-Counter Medicines Safe Daily Use of Aspirin Aspirin for Reducing Your Risk of Heart Attack and ... any pharmacy, grocery or convenience store and buy aspirin without a prescription. The Drug Facts label on ...

  2. Impact of Metric Selection on Wireless DeAuthentication DoS Attack Performance

    OpenAIRE

    Milliken, Jonny; Selis, Valerio; Yap, Kian Meng; Marshall, Alan

    2013-01-01

    DeAuthentication Denial of Service attacks in Public Access WiFi operate by exploiting the lack of authentication of management frames in the 802.11 protocol. Detection of these attacks rely almost exclusively on the selection of appropriate thresholds. In this work the authors demonstrate that there are additional, previously unconsidered, metrics which also influence DoS detection performance. A method of systematically tuning these metrics to optimal values is proposed which ensures that p...

  3. Blocking of SQL Injection Attacks by Comparing Static and Dynamic Queries

    Directory of Open Access Journals (Sweden)

    Raman Kumar

    2013-02-01

    Full Text Available Due to internet expansion web applications have now become a part of everyday life. As a result a number of incidents which exploit web application vulnerabilities are increasing. A large number of these incidents are SQL Injection attacks which are a serious security threat to databases which contain sensitive information, the leakage of which cause a large amount of loss. SQL Injection Attacks occur when an intruder changes the query structure by inserting any malicious input. There are a number of methods available to detect and prevent SQL Injection Attacks. But these are too complex to use. This paper proposes a very simple, effective and time saving technique to detect SQLIAs which uses combined static and dynamic analysis and also defines an attack other than existing classification of SQLIAs.

  4. Impacts of tropical cyclone inflow angle on ocean surface waves

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; HONG Xin

    2011-01-01

    The inflow angle of tropical cyclones (TC) is generally neglected in numerical studies of ocean surface waves induced by TC. In this study, the impacts of TC inflow angle on ocean surface waves were investigated using a high-resolution wave model. Six numerical experiments were conducted to examine, in detail, the effects of inflow angle on mean wave parameters and the spectrum of wave directions. A comparison of the waves simulated in these experiments shows that inflow angle significantly modifies TC-induced ocean surface waves. As the inflow angle increases, the asymmetric axis of the significant wave height (SWH) field shifts 30° clockwise, and the maximum SWH moves from the front-right to the rear-right quadrant. Inflow angle also affects other mean wave parameters, especially in the rear-left quadrant, such as the mean wave direction, the mean wavelength, and the peak direction. Inflow angle is a key factor in wave models for the reproduction of double-peak or multi-peak patterns in the spectrum of wave directions. Sensitivity experiments also show that the simulation with a 40° inflow angle is the closest to that of the NOAA statistical SLOSH inflow angle. This suggests that 40° can be used as the inflow angle in future TC-induced ocean surface wave simulations when SLOSH or observed inflow angles are not available.

  5. Agent-Based Modeling and Simulation of Network Infrastructure Cyber-Attacks and Cooperative Defense Mechanisms

    OpenAIRE

    Kotenko, Igor

    2010-01-01

    This paper considered the approach to investigation of distributed cooperative cyberdefence mechanisms against network attacks. The approach is based on the simulation of network cyber-attacks (Distributed Denial of Service, network worms, botnets, etc.) and cyber-protection mechanisms which combines discrete-event simulation, multi-agent approach and packet-level simulation of network protocols. The environment developed is written in C++ and OMNeT++. It allows imitating a wide spectrum of r...

  6. Unilateral comminuted and complicated fracture of the mandible due to dog attack

    OpenAIRE

    Ngeow, W.C.; Lian, C.B.

    1996-01-01

    Fractures of the mandible and their management are discussed in detail in textbooks and articles dealing with facial trauma. This paper presents the management and treatment of a case of a unilateral comminuted and complicated fracture of the mandible due to dog attack on a geriatric patient. The attack also severed the patient's right arm. Due to the severity of the trauma, an emergency surgery was performed on the mandible and arm.

  7. Value of ABCD2 in predicting early ischemic stroke in patients diagnosed with transient ischemic attack.

    OpenAIRE

    Mojtaba Chardoli; Alireza Khajavi; Mohsen Nouri; Vafa Rahimi-Movaghar

    2013-01-01

    As a significant number of patients diagnosed with transient ischemic attack (TIA) at emergency department are at risk to develop TIA or cerebral vascular accident (CVA), several attempts have been made to figure out a predictive method to detect those at higher risk of such attacks. We aimed to evaluate the role of ABCD2 scoring which includes age, blood pressure, clinical symptoms, diabetes mellitus, and duration of symptoms in predicting short term outcome of the patients presenting with T...

  8. Attack Assignments in Terror Organizations and The Productivity of Suicide Bombers

    OpenAIRE

    Efraim Benmelech; Claude Berrebi

    2007-01-01

    This paper studies the relation between human capital of suicide bombers and outcomes of their suicide attacks. We argue that human capital is an important factor in the production of terrorism, and that if terrorists behave rationally we should observe that more able suicide bombers are assigned to more important targets. We use a unique data set detailing the biographies of Palestinian suicide bombers, the targets they attack, and the number of people that they kill and injure to validate t...

  9. Blocking of SQL Injection Attacks by Comparing Static and Dynamic Queries

    OpenAIRE

    Raman Kumar; Jaskanwal Minhas

    2013-01-01

    Due to internet expansion web applications have now become a part of everyday life. As a result a number of incidents which exploit web application vulnerabilities are increasing. A large number of these incidents are SQL Injection attacks which are a serious security threat to databases which contain sensitive information, the leakage of which cause a large amount of loss. SQL Injection Attacks occur when an intruder changes the query structure by inserting any malicious input. There are a n...

  10. Detection and Prevention of Gray Hole and Black Hole Attack in MANET

    Directory of Open Access Journals (Sweden)

    Deepali Raut

    2014-08-01

    Full Text Available An Ad hoc network is the network with no fixed infrastructure. There is no central administrator so any node can come and move in and outside of the network in a dynamic manner. This makes it more dynamic and complex which makes it more prone to attacks. They can attack either active or passive. Some effects of malicious nodes are Denial of service, Routing table overflow, Impersonation, Energy consumption, Information disclosure etc. A black hole attack node attracts all packets by falsely claiming a fresh route to the destination node and absorbs them without forwarding them to destination. In this work the effect of Black hole and Gray Hole attack on DSR protocol has been considered. Simulation has been performed on the basis of performance parameters and effect has been analyzed using NS2 simulator. 

  11. On the study of replay and voice conversion attacks to text-dependent speaker verification

    OpenAIRE

    Wu, Zhizheng; Li, Haizhou

    2015-01-01

    Automatic speaker verification (ASV) is to automatically accept or reject a claimed identity based on a speech sample. Recently, individual studies haveconfirmed the vulnerability of state-of-the-art text-independent ASV systems under replay, speech synthesis and voice conversion attacks on various databases. However, the behaviours of text-dependent ASV systems have not been systematically assessed in the face of various spoofing attacks. In this work, we first conduct a systematic analysis ...

  12. Analysis and Reduction of Stray-Current Attack in Reciprocated Traveling Wire Electrochemical Machining

    OpenAIRE

    Zeng, Yongbin; Ji, Huajian; Fang, Xiaolong; Wang, Yufeng; Qu, Ningsong

    2014-01-01

    Traveling wire electrochemical machining is a promising approach for the fabrication of various metal parts. However, the stray-current attack deteriorates the surface quality while it is employed to cut thick workpiece as a normal pulse or DC is used. In this paper, the characteristics of the stray-current attack in reciprocated traveling wire electrochemical machining are firstly identified, and special insulating methods are proposed to reduce the effect of the stray-current. The model of ...

  13. Risk Assessment Tool for Estimating Your 10-Year Risk of Having a Heart Attack

    Science.gov (United States)

    ... Education Programs Continuing Education Opportunities Health Observances Risk Assessment Tool for Estimating Your 10-year Risk of Having a Heart Attack The risk assessment tool below uses information from the Framingham Heart ...

  14. Vulnerability Assessment of IPv6 Websites to SQL Injection and Other Application Level Attacks

    Directory of Open Access Journals (Sweden)

    Ying-Chiang Cho

    2013-01-01

    Full Text Available Given the proliferation of internet connected devices, IPv6 has been proposed to replace IPv4. Aside from providing a larger address space which can be assigned to internet enabled devices, it has been suggested that the IPv6 protocol offers increased security due to the fact that with the large number of addresses available, standard IP scanning attacks will no longer become feasible. However, given the interest in attacking organizations rather than individual devices, most initial points of entry onto an organization's network and their attendant devices are visible and reachable through web crawling techniques, and, therefore, attacks on the visible application layer may offer ways to compromise the overall network. In this evaluation, we provide a straightforward implementation of a web crawler in conjunction with a benign black box penetration testing system and analyze the ease at which SQL injection attacks can be carried out.

  15. Vulnerability assessment of IPv6 websites to SQL injection and other application level attacks.

    Science.gov (United States)

    Cho, Ying-Chiang; Pan, Jen-Yi

    2013-01-01

    Given the proliferation of internet connected devices, IPv6 has been proposed to replace IPv4. Aside from providing a larger address space which can be assigned to internet enabled devices, it has been suggested that the IPv6 protocol offers increased security due to the fact that with the large number of addresses available, standard IP scanning attacks will no longer become feasible. However, given the interest in attacking organizations rather than individual devices, most initial points of entry onto an organization's network and their attendant devices are visible and reachable through web crawling techniques, and, therefore, attacks on the visible application layer may offer ways to compromise the overall network. In this evaluation, we provide a straightforward implementation of a web crawler in conjunction with a benign black box penetration testing system and analyze the ease at which SQL injection attacks can be carried out. PMID:24574863

  16. Superwide-angle acoustic propagations above the critical angles of the Snell law in liquid—solid superlattice

    International Nuclear Information System (INIS)

    In this paper, superwide-angle acoustic propagations above the critical angles of the Snell law in liquid—solid superlattice are investigated. Incident waves above the critical angles of the Snell law usually inevitably induce total reflection. However, incident waves with big oblique angles through the liquid—solid superlattice will produce a superwide angle transmission in a certain frequency range so that total reflection does not occur. Together with the simulation by finite element analysis, theoretical analysis by using transfer matrix method suggests the Bragg scattering of the Lamb waves as the physical mechanism of acoustic wave super-propagation far beyond the critical angle. Incident angle, filling fraction, and material thickness have significant influences on propagation. Superwide-angle propagation phenomenon may have potential applications in nondestructive evaluation of layered structures and controlling of energy flux. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  17. Visualization of the Serratia Type VI Secretion System Reveals Unprovoked Attacks and Dynamic Assembly

    OpenAIRE

    Amy J. Gerc; Andreas Diepold; Katharina Trunk; Michael Porter; Colin Rickman; Judith P. Armitage; Nicola R. Stanley-Wall; Sarah J. Coulthurst

    2015-01-01

    Summary The Type VI secretion system (T6SS) is a bacterial nanomachine that fires toxic proteins into target cells. Deployment of the T6SS represents an efficient and widespread means by which bacteria attack competitors or interact with host organisms and may be triggered by contact from an attacking neighbor cell as a defensive strategy. Here, we use the opportunist pathogen Serratia marcescens and functional fluorescent fusions of key components of the T6SS to observe different subassembli...

  18. Predicting value of ABCD2 in early ischemic stroke in patients diagnosed with transient ischemic attack

    OpenAIRE

    Chardoli, Mojtaba; Khajavi, Alireza; Nouri, Mohsen; Rahimi-Movaghar, Vafa

    2012-01-01

    Abstract: Background: As a significant number of patients diagnosed with transient ischemic attack (TIA) at emergency department are at risk to develop TIA or cerebral vascular accident (CVA), several attempts have been made to figure out a predictive method to detect those at higher risk of such attacks. Therefore, the present study was aimed to evaluate the role of ABCD2 scoring including age, blood pressure, clinical features, duration, and diabetes mellitus (DM), in predicting short term ...

  19. A Possible Effect of Concentrated Oolong Tea Causing Transient Ischemic Attack-Like Symptoms

    OpenAIRE

    Layher, John W.; Poling, Jon S.; Ishihara, Mayumi; Azadi, Parastoo; Alvarez-Manilla, Gerardo; Puett, David

    2013-01-01

    Aims Tea (green, oolong, and black) is the second most widely consumed beverage worldwide, second only to water. Aside from a few reported adverse effects, tea, particularly green tea, appears to be beneficial for human health. In the case described herein, a male experienced several transient ischemic attack-like symptoms immediately following the consumption of a cup of high quality oolong tea. A thorough medical evaluation uncovered no evidence of such an attack and leads to the suggestion...

  20. A Possible Effect of Concentrated Oolong Tea Causing Transient Ischemic Attack-Like Symptoms

    OpenAIRE

    Layher Jr., John W.; Poling, Jon S.; Ishihara, Mayumi; Azadi, Parastoo; Alvarez-Manilla, Gerardo; Puett, David

    2013-01-01

    Aims: Tea (green, oolong, and black) is the second most widely consumed beverage worldwide, second only to water. Aside from a few reported adverse effects, tea, particularly green tea, appears to be beneficial for human health. In the case described herein, a male experienced several transient ischemic attack-like symptoms immediately following the consumption of a cup of high quality oolong tea. A thorough medical evaluation uncovered no evidence of such an attack and leads to the suggestio...