2,739 research outputs found
Dispersion engineering of infrared epsilon-near-zero modes by strong coupling to optical cavities
Epsilon-near-zero (ENZ) materials have recently emerged as a promising
platform for infrared nanophotonics. A significant challenge in the design of
ENZ-based optics is to control the dispersion of ENZ modes, which otherwise
have a flat profile near the ENZ frequency. Strong coupling with an optical
cavity is a promising approach to ENZ dispersion engineering, which however has
limitations due to the lack of tunability or nanofabrication demands of the
cavity employed. Here, we theoretically and numerically show that much of the
limitations of previous demonstrations can be overcome by strongly coupling the
ENZ mode to an unpatterned Fabry-Perot cavity. We demonstrate this
unprecedented ENZ dispersion control in coupled cavities by designing tunable
infrared polarizers that can absorb s- and reflect p-polarized components, or
vice versa, for almost any oblique angle of incidence, i.e. omnidirectional
polarizers. The feasibility of active control is also demonstrated using a
phase change material within the cavity, which predicts dynamic switchability
of polariton dispersions across multiple resonant levels at mid-infrared
wavelengths. These results are expected to advance the current understanding of
strongly coupled ENZ interactions and demonstrate their potential in tailoring
dispersions for active and passive control of light
STEM@1000mph: developing open educational resources in a live engineering project
Higher education institutions are recognising the clear benefits of open educational resources, and academics are engaging with the development of these resources. This paper presents a case study of OERs being developed using the live, current BloodhoundSSC world land speed record project as a basis. The paper outlines the rationale for the BloodhoundSSC project and its focus on educational engagement across the age spectrum. The work undertaken to develop a web-based repository along with activities to stimulate academic and student engagement are described. The paper explores how academics have engaged with developing OERs based on this openly available content, the issues encountered and ways in which these issues can be mitigated
Hot gas ingestion characteristics and flow visualization of a vectored thrust STOVL concept
A 9.2 percent scale short takeoff and vertical landing (STOVL) hot gas ingestion model was designed and built by McDonnell Douglas Corporation (MCAIR) and tested in the NASA Lewis Research Center 9- by 15-Foot Low Speed Wind Tunnel (LSWT). Hot gas ingestion, the entrainment of heated engine exhaust into the inlet flow field, is a key development issue for advanced short takeoff and vertical landing aircraft. The Phase 1 test program, conducted by NASA Lewis and McDonnell Douglas Corporation, evaluated the hot ingestion phenomena and control techniques and Phase 2 test program which was conducted by NASA Lewis are both reported. The Phase 2 program was conducted at exhaust nozzles temperatures up to 1460 R and utilized a sheet laser system for flow visualization of the model flow field in and out of ground effects. Hot gas ingestion levels were measured for the several forward nozzle splay configurations and with flow control/lift improvement devices which reduced the hot gas ingestion. The model support system had four degrees of freedom, heated high pressure air for nozzle flow, and a suction system exhaust for inlet flow. The headwind (freestream) velocity for Phase 1 was varied from 8 to 90 kn, with primary data taken in the 8 to 23 kn headwind velocity range. Phase 2 headwind velocity varied from 10 to 23 kn. Results of both Phase 1 and 2 are presented. A description of the model, facility, a new model support system, and a sheet laser illumination system are also provided. Results are presented over a range of main landing gear height (model height) above the ground plane at a 10 kn headwind velocity. The results contain the compressor face pressure and temperature distortions, total pressure recovery, compressor face temperature rise, and the environmental effects of the hot gas. The environmental effects include the ground plane temperature and pressure distributions, model airframe heating, and the location of the ground flow separation. Results from the sheet laser flow visualization test are also shown
25 Million Flows Later - Large-scale Detection of DOM-based XSS
In recent years, the Web witnessed a move towards sophis- ticated client-side functionality. This shift caused a signifi- cant increase in complexity of deployed JavaScript code and thus, a proportional growth in potential client-side vulnera- bilities, with DOM-based Cross-site Scripting being a high impact representative of such security issues. In this paper, we present a fully automated system to detect and validate DOM-based XSS vulnerabilities, consisting of a taint-aware JavaScript engine and corresponding DOM implementation as well as a context-sensitive exploit generation approach. Using these components, we conducted a large-scale analysis of the Alexa top 5000. In this study, we identified 6167 unique vulnerabilities distributed over 480 domains, show- ing that 9,6% of the examined sites carry at least one DOM- based XSS problem
Eradicating DNS Rebinding with the Extended Same-Origin Policy
The Webâs principal security policy is the Same-Origin Policy (SOP), which enforces origin-based isolation of mutually distrusting Web applications. Since the early days, the SOP was repeatedly undermined with variants of the DNS Rebinding attack, allowing untrusted script code to gain illegitimate access to protected network resources. To counter these attacks, the browser vendors introduced countermeasures, such as DNS Pinning, to mitigate the attack. In this paper, we present a novel DNS Rebinding attack method leveraging the HTML5 Application Cache. Our attack allows reliable DNS Rebinding attacks, circumventing all currently deployed browser-based defense measures. Furthermore, we analyze the fundamental problem which allows DNS Rebinding to work in the first place: The SOPâs main purpose is to ensure security boundaries of Web servers. However, the Web servers themselves are only indirectly involved in the corresponding security decision. Instead, the SOP relies on information obtained from the domain name system, which is not necessarily controlled by the Web serverâs owners. This mismatch is exploited by DNS Rebinding. Based on this insight, we propose a light-weight extension to the SOP which takes Web server provided information into account. We successfully implemented our extended SOP for the Chromium Web browser and report on our implementationâs interoperability and security properties
Donât Trust The Locals: Investigating the Prevalence of Persistent Client-Side Cross-Site Scripting in the Wild.
The Web has become highly interactive and an
important driver for modern life, enabling information retrieval,
social exchange, and online shopping. From the security perspective, Cross-Site Scripting (XSS) is one of the most nefarious
attacks against Web clients. Research has long since focused
on three categories of XSS: Reflected, Persistent, and DOMbased XSS. In this paper, we argue that our community must
consider at least four important classes of XSS, and present
the first systematic study of the threat of Persistent Client-Side
XSS, caused by the insecure use of client-side storage. While
the existence of this class has been acknowledged, especially by
the non-academic community like OWASP, prior works have
either only found such flaws as side effects of other analyses or
focused on a limited set of applications to analyze. Therefore, the
community lacks in-depth knowledge about the actual prevalence
of Persistent Client-Side XSS in the wild.
To close this research gap, we leverage taint tracking to
identify suspicious flows from client-side persistent storage (Web
Storage, cookies) to dangerous sinks (HTML, JavaScript, and
script.src). We discuss two attacker models capable of
injecting malicious payloads into storage, i.e., a Network Attacker
capable of temporarily hijacking HTTP communication (e.g., in
a public WiFi), and a Web Attacker who can leverage flows into
storage or an existing reflected XSS flaw to persist their payload.
With our taint-aware browser and these models in mind, we
study the prevalence of Persistent Client-Side XSS in the Alexa
Top 5,000 domains. We find that more than 8% of them have
unfiltered data flows from persistent storage to a dangerous sink,
which showcases the developersâ inherent trust in the integrity
of storage content. Even worse, if we only consider sites that
make use of data originating from storage, 21% of the sites are
vulnerable. For those sites with vulnerable flows from storage
to sink, we find that at least 70% are directly exploitable by
our attacker models. Finally, investigating the vulnerable flows
originating from storage allows us to categorize them into four
disjoint categories and propose appropriate mitigations
Exploring the use of routinely-available, retrospective data to study the association between malaria control scale-up and micro-economic outcomes in Zambia
Additional file 1. Additional tables that share additional results of the generalized propensity score matching analysis, as well as a table covering malaria control coverage at the district level
Tumour-derived leukaemia inhibitory factor is a major driver of cancer cachexia and morbidity in C26 tumour-bearing mice
BACKGROUND: Cancer cachexia is a metabolic wasting syndrome that is strongly associated with a poor prognosis. The initiating factors causing fat and muscle loss are largely unknown. Previously, we found that leukaemia inhibitory factor (LIF) secreted by C26 colon carcinoma cells was responsible for atrophy in treated myotubes. In the present study, we tested whether C26 tumourâderived LIF is required for cancer cachexia in mice by knockout of Lif in C26 cells.
METHODS: A C26 Lif null tumour cell line was made using CRISPRâCas9. Measurements of cachexia were compared in mice inoculated with C26 vs. C26^Lifâ/â tumour cells, and atrophy was compared in myotubes treated with medium from C26 vs. C26^Lifâ/â tumour cells. Levels of 25 cytokines/chemokines were compared in serum of mice bearing C26 vs. C26^Lifâ/â tumours and in the medium from these tumour cell lines.
RESULTS: At study endpoint, C26 mice showed outward signs of sickness while mice with C26^Lifâ/â tumours appeared healthy. Mice with C26^Lifâ/â tumours showed a 55â75% amelioration of body weight loss, muscle loss, fat loss, and splenomegaly compared with mice with C26 tumours (P < 0.05). The heart was not affected by LIF levels because the loss of cardiac mass was the same in C26 and C^26Lifâ/â tumourâbearing mice. LIF levels in mouse serum was entirely dependent on secretion from the tumour cells. Serum levels of interleukinâ6 and GâCSF were increased by 79âfold and 68âfold, respectively, in C26 mice but only by fiveâfold and twoâfold, respectively, in C26^Lifâ/â mice, suggesting that interleukinâ6 and GâCSF increases are dependent on tumourâderived LIF.
CONCLUSIONS: This study shows the first use of CRISPRâCas9 knockout of a candidate cachexia factor in tumour cells. The results provide direct evidence for LIF as a major cachexia initiating factor for the C26 tumour in vivo. Tumourâderived LIF was also a regulator of multiple cytokines in C26 tumour cells and in C26 tumourâbearing mice. The identification of tumourâderived factors such as LIF that initiate the cachectic process is immediately applicable to the development of therapeutics to treat cachexia. This is a proof of principle for studies that when carried out in human cells, will make possible an understanding of the factors causing cachexia in a patientâspecific manner.This work was supported by NIAMS R01AR060217 to S. C. K. and R. W. J. and NIAMS R01 R01AR060209 to A. R. J., and by the Dudley Allen Sargent Research Fund. The authors certify that they comply with the ethical guidelines for publishing in the Journal of Cachexia, Sarcopenia and Muscle: update 2017.40 (R01AR060217 - NIAMS; R01 R01AR060209 - NIAMS; Dudley Allen Sargent Research Fund)Published versio
Generalized cost-effectiveness analysis for national-level priority-setting in the health sector
Cost-effectiveness analysis (CEA) is potentially an important aid to public health decision-making but, with some notable exceptions, its use and impact at the level of individual countries is limited. A number of potential reasons may account for this, among them technical shortcomings associated with the generation of current economic evidence, political expediency, social preferences and systemic barriers to implementation. As a form of sectoral CEA, Generalized CEA sets out to overcome a number of these barriers to the appropriate use of cost-effectiveness information at the regional and country level. Its application via WHO-CHOICE provides a new economic evidence base, as well as underlying methodological developments, concerning the cost-effectiveness of a range of health interventions for leading causes of, and risk factors for, disease. The estimated sub-regional costs and effects of different interventions provided by WHO-CHOICE can readily be tailored to the specific context of individual countries, for example by adjustment to the quantity and unit prices of intervention inputs (costs) or the coverage, efficacy and adherence rates of interventions (effectiveness). The potential usefulness of this information for health policy and planning is in assessing if current intervention strategies represent an efficient use of scarce resources, and which of the potential additional interventions that are not yet implemented, or not implemented fully, should be given priority on the grounds of cost-effectiveness. Health policy-makers and programme managers can use results from WHO-CHOICE as a valuable input into the planning and prioritization of services at national level, as well as a starting point for additional analyses of the trade-off between the efficiency of interventions in producing health and their impact on other key outcomes such as reducing inequalities and improving the health of the poor
- âŠ