2,731 research outputs found
DoS Attack Impact Assessment on Software Defined Networks
© 2018, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. Software Defined Networking (SDN) is an evolving network paradigm which promises greater interoperability, more innovation, flexible and effective solutions. Although SDN on the surface provides a simple framework for network programmability and monitoring, few has been said about security measures to make it resilient to hitherto security flaws in traditional network and the new threats the architecture is ushering in. One of the security weaknesses the architecture is ushering in due to separation of control and data plane is Denial of Service (DoS) attack. The main goal of this attack is to make network resources unavailable to legitimate users or introduce large delays. In this paper, the effect of DoS attack on SDN is presented using Mininet, OpenDaylight (ODL) controller and network performance testing tools such as iperf and ping. Internet Control Message Protocol (ICMP) flood attack is performed on a Transmission Control Protocol (TCP) server and a User Datagram Protocol (UDP) server which are both connected to OpenFlow switches. The simulation results reveal a drop in network throughput from 233 Mbps to 87.4 Mbps and the introduction of large jitter between 0.003 ms and 0.789 ms during DoS attack.Published versio
Large sharing networks and unusual injection practices explain the rapid rise in HIV among IDUs in Sargodha, Pakistan
<p>Abstract</p> <p>Background</p> <p>Of the nearly 100,000 street-based IDUs in Pakistan, 20% have HIV. We investigated the recent rise in HIV prevalence from 12 to 52% among IDUs in Sargodha despite > 70% coverage with syringe exchanges.</p> <p>Methods</p> <p>We interviewed approximately 150 IDUs and 30 outreach workers in focus group discussions.</p> <p>Results</p> <p>We found six rural and 28 urban injecting locations. Urban locations have about 20â30 people at any time and about 100 daily; rural locations have twice as many (national average: 4â15). About half of the IDUs started injecting within the past 2 years and are not proficient at injecting themselves. They use street injectors, who have 15â16 clients daily. Heroin is almost exclusively the drug used. Most inject 5â7 times daily.</p> <p>Nearly all injectors claim to use fresh syringes. However, they load, inject and share using a locally developed method called scale. Most Pakistani IDUs prefer to double pump drug the syringe, which allows mixing of blood with drug in the syringe. The injector injects 3 ml and keeps 2 ml (the scale) as injection fee. The injector usually pools all the leftover scale (now with some blood mixed with drug) either for his own use or to sell it. Most IDUs backload the scale they buy into their own fresh syringes.</p> <p>Discussion</p> <p>Use of an unprecedented method of injecting drugs that largely bypasses fresh syringes, larger size of sharing networks, higher injection frequency and near universal use of street injectors likely explain for the rapid rise in HIV prevalence among IDUs in Sargodha despite high level provision of fresh syringes. This had been missed by us and the national surveillance, which is quantitative. We have addressed this by hiring injectors as peer outreach workers and increasing syringe supply. Our findings highlight both the importance of qualitative research and operations research to enrich the quality of HIV prevention programs.</p
Panics and Principles: A History of Drug Education Policy in New South Wales 1965-1999
When the problem of young people using illegal drugs for recreation emerged in New South Wales in the 1960s drug education was promoted by governments and experts as a humane alternative to policing. It developed during the 1970s and 1980s as the main hope for preventing drug problems amongst young people in the future. By the 1990s drug policy experts, like their temperance forbears, had become disillusioned with drug education, turning to legislative action for the prevention of alcohol and other drug problems. However, politicians and the community still believed that education was the best solution. Education Departments, reluctant to expose schools to public controversy, met minimal requirements. This thesis examines the ideas about drugs, education and youth that influenced the construction and implementation of policies about drug education in New South Wales between 1965 and 1999. It also explores the processes that resulted in the defining of drug problems and beliefs about solutions, identifying their contribution to policy and the way in which this policy was implemented. The thesis argues that the development of drug education over the last fifty years has been marked by three main cycles of moral panic about youth drug use. It finds that each panic was triggered by the discovery of the use of a new illegal substance by a youth subculture. Panics continued, however, because of the tension between two competing notions of young peopleâs drug use. In the traditional dominant view âdrugâ meant illegal drugs, young peopleâs recreational drug use was considered to be qualitatively different to that of adults, and illegal drugs were the most serious and concerning problem. In the newer alternative âpublic healthâ view which began developing in the 1960s, illicit drug use was constructed as part of normal experimentation, alcohol, tobacco and prescribed medicines were all drugs, and those who developed problems with their use were sick, not bad. These public health principles were formulated in policy documents on many occasions. The cycles of drug panic were often an expression of anxiety about the new approach and they had the effect of reasserting the dominant view. The thesis also finds that the most significant difference between the two discourses lies in the way that alcohol is defined, either as a relatively harmless beverage or as a drug that is a major cause of harm. Public health experts have concluded that alcohol poses a much greater threat to the health and safety of young people than illegal drugs. However, parents, many politicians and members of the general community have believed for the last fifty years that alcohol is relatively safe. Successive governments have been influenced by the economic power of the alcohol industry to support the latter view. Thus the role of alcohol and its importance to the economy in Australian society is a significant hindrance in reconciling opposing views of the drug problem and developing effective drug education. The thesis concludes that well justified drug education programs have not been implemented fully because the rational approaches to drug education developed by experts have not been supported by the dominant discourse about the drug problem. Politicians have used drug education as a populist strategy to placate fear but the actual programs that have been developed attempt to inform young people and the community about the harms and benefits of all drugs. When young people take up the use of a new mood altering drug, the rational approach developed by public health experts provokes intense anxiety in the community and the idea that legal substances such as alcohol, tobacco and prescribed drugs can cause serious harm to young people is rejected in favour of an approach that emphasizes the danger of illegal drug use
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The LSST DESC data challenge 1: Generation and analysis of synthetic images for next-generation surveys
Data Challenge 1 (DC1) is the first synthetic data set produced by the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration (DESC). DC1 is designed to develop and validate data reduction and analysis and to study the impact of systematic effects that will affect the LSST data set. DC1 is comprised of r-band observations of 40 deg2 to 10 yr LSST depth. We present each stage of the simulation and analysis process: (a) generation, by synthesizing sources from cosmological N-body simulations in individual sensor-visit images with different observing conditions; (b) reduction using a development version of the LSST Science Pipelines; and (c) matching to the input cosmological catalogue for validation and testing. We verify that testable LSST requirements pass within the fidelity of DC1. We establish a selection procedure that produces a sufficiently clean extragalactic sample for clustering analyses and we discuss residual sample contamination, including contributions from inefficiency in star-galaxy separation and imperfect deblending. We compute the galaxy power spectrum on the simulated field and conclude that: (i) survey properties have an impact of 50 per cent of the statistical uncertainty for the scales and models used in DC1; (ii) a selection to eliminate artefacts in the catalogues is necessary to avoid biases in the measured clustering; and (iii) the presence of bright objects has a significant impact (2-6) in the estimated power spectra at small scales (> 1200), highlighting the impact of blending in studies at small angular scales in LSST
Design of Multicationic Copper-Bearing Layered Double Hydroxides for Catalytic Application in Biorefinery
Ethanol has been used as a renewable hydrogen-donor in the conversion of a lignin model molecule in subcritical conditions. Noble metal-free porous mixed oxides, obtained by activation of Cu-Ni-Al and Cu-Ni-Fe layered double hydroxide (LDH) precursors, have been used as heterogeneous catalysts for Meerwein-Ponndorf-Verley (MPV) hydrogen transfer and further hydrogenation by ethanol dehydrogenation products. Both the Cu/(Cu+Ni) ratio and the nature of the trivalent cation (Al or Fe) affect the activity of the catalysts, as well as the selectivity towards the different steps of the hydrogenation reactions and the cleavage of lignin-like phenylether bonds. Accounting for the peculiar behaviour of Cu2+ and M(III) cations in the synthesis of LDHs, the coprecipitation of the precursors has been monitored by titration experiments. Structural and textural properties of the catalysts are closely related to the composition of the LDH precursors
A novel application of Lobatto iiia solver for numerical treatment of mixed convection nanofluidic model
The objective of the current investigation is to examine the influence of variable viscosity and transverse magnetic field on mixed convection fluid model through stretching sheet based on copper and silver nanoparticles by exploiting the strength of numerical computing via Lobatto IIIA solver. The nonlinear partial differential equations are changed into ordinary differential equations by means of similarity transformations procedure. A renewed finite difference based Lobatto IIIA method is incorporated to solve the fluidic system numerically. Vogel's model is considered to observe the influence of variable viscosity and applied oblique magnetic field with mixed convection along with temperature dependent viscosity. Graphical and numerical illustrations are presented to visualize the behavior of different sundry parameters of interest on velocity and temperature. Outcomes reflect that volumetric fraction of nanoparticles causes to increase the thermal conductivity of the fluid and the temperature enhances due to blade type copper nanoparticles. The convergence analysis on the accuracy to solve the problem is investigated viably though the residual errors with different tolerances to prove the worth of the solver. The temperature of the fluid accelerates due the blade type nanoparticles of copper and skin friction coefficient is reduced due to enhancement of Grashof Number
Performance of a Large-Area GEM Detector Prototype for the Upgrade of the CMS Muon Endcap System
Gas Electron Multiplier (GEM) technology is being considered for the forward
muon upgrade of the CMS experiment in Phase 2 of the CERN LHC. Its first
implementation is planned for the GE1/1 system in the region of the muon endcap mainly to control muon level-1 trigger rates
after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by
3,072 radial strips with 455 rad pitch arranged in eight -sectors.
We assembled a full-size GE1/1 prototype of 1m length at Florida Tech and
tested it in 20-120 GeV hadron beams at Fermilab using Ar/CO 70:30 and
the RD51 scalable readout system. Four small GEM detectors with 2-D readout and
an average measured azimuthal resolution of 36 rad provided precise
reference tracks. Construction of this largest GEM detector built to-date is
described. Strip cluster parameters, detection efficiency, and spatial
resolution are studied with position and high voltage scans. The plateau
detection efficiency is [97.1 0.2 (stat)]\%. The azimuthal resolution is
found to be [123.5 1.6 (stat)] rad when operating in the center of
the efficiency plateau and using full pulse height information. The resolution
can be slightly improved by 10 rad when correcting for the bias due
to discrete readout strips. The CMS upgrade design calls for readout
electronics with binary hit output. When strip clusters are formed
correspondingly without charge-weighting and with fixed hit thresholds, a
position resolution of [136.8 2.5 stat] rad is measured, consistent
with the expected resolution of strip-pitch/ = 131.3 rad. Other
-sectors of the detector show similar response and performance.Comment: 8 pages, 32 figures, submitted to Proc. 2014 IEEE Nucl. Sci.
Symposium, Seattle, WA, reference adde
A novel application of Fiber Bragg Grating (FBG) sensors in MPGD
We present a novel application of Fiber Bragg Grating (FBG) sensors in the
construction and characterisation of Micro Pattern Gaseous Detector (MPGD),
with particular attention to the realisation of the largest triple (Gas
electron Multiplier) GEM chambers so far operated, the GE1/1 chambers of the
CMS experiment at LHC. The GE1/1 CMS project consists of 144 GEM chambers of
about 0.5 m2 active area each, employing three GEM foils per chamber, to be
installed in the forward region of the CMS endcap during the long shutdown of
LHC in 2108-2019. The large active area of each GE1/1 chamber consists of GEM
foils that are mechanically stretched in order to secure their flatness and the
consequent uniform performance of the GE1/1 chamber across its whole active
surface. So far FBGs have been used in high energy physics mainly as high
precision positioning and re-positioning sensors and as low cost, easy to
mount, low space consuming temperature sensors. FBGs are also commonly used for
very precise strain measurements in material studies. In this work we present a
novel use of FBGs as flatness and mechanical tensioning sensors applied to the
wide GEM foils of the GE1/1 chambers. A network of FBG sensors have been used
to determine the optimal mechanical tension applied and to characterise the
mechanical tension that should be applied to the foils. We discuss the results
of the test done on a full-sized GE1/1 final prototype, the studies done to
fully characterise the GEM material, how this information was used to define a
standard assembly procedure and possible future developments.Comment: 4 pages, 4 figures, presented by Luigi Benussi at MPGD 2015 (Trieste,
Italy). arXiv admin note: text overlap with arXiv:1512.0848
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