2,439 research outputs found
Simple authentication and security layer incorporating extensible authentication protocol
There are many methods that support user authentication and access control, important roles in the establishment of secure communication. Particularly, we examine Simple Authentication and Security Layer (SASL) and Extensible Authentication Protocol (EAP) and propose EAP-Advanced Encryption Standard-Pre-Shared-Key (EAP-AES-PSK). SASL is an authentication framework in connection-oriented protocols. EAP is an authentication framework providing multiple authentication methods. SASL is vulnerable to the dictionary attack, replay attack, and Man-In-The-Middle attack as well as the re-keying issue. We propose to incorporate EAP into SASL to enhance the security of SASL and to provide a pathway for easy incorporation of future EAP enhancements into SASL. Standalone EAP still faces some common attacks. We propose EAP-AES-PSK, a new EAP method, to provide strong authentication and we implement this method on the Cyrus SASL implementation: one of the publicly available SASL implementations. This project is evaluated through the verification of functionality of a SASL application incorporating EAR Further, we argue how the common security risks associated with SASL are addressed, and we complete a performance evaluation of the new method incorporated into SASL
Continuum-based Multiscale Computational Damage Modeling of Cementitous Composites
Based on continuum damage mechanics (CDM), an isotropic and anisotropic damage
model coupled with a novel plasticity model for plain concrete is proposed in this
research. Two different damage evolution laws for both tension and compression are
formulated for a more accurate prediction of the plain concrete behavior. In order to
derive the constitutive equations, the strain equivalence hypothesis is adopted. The
proposed constitutive model has been shown to satisfy the thermodynamics requirements,
and detailed numerical algorithms are developed for the Finite Element implementation
of the proposed model. Moreover, the numerical algorithm is coded using the user
subroutine UMAT and then implemented in the commercial finite element analysis
program Abaqus, and the overall performance of the proposed model is verified by
comparing the model predictions to various experimental data on macroscopic level.
Using the proposed coupled plasticity-damage constitutive model, the effect of
the micromechanical properties of concrete, such as aggregate shape, distribution, and
volume fraction, the ITZ thickness, and the strength of the ITZ and mortar matrix on the tensile behavior of concrete is investigated on 2-D and 3-D meso-scale. As a result of
simulation, the tensile strength and thickness of the ITZ is the most important factor that
control the global strength and behavior of concrete, and the aggregate shape and
volume fraction has somewhat effect on the tensile behavior of concrete while the effect
of the aggregate distribution is negligible. Furthermore, using the proposed constitutive
model, the pull-out analysis of the single straight and curved CNT embedded in cement
matrix is carried out. In consequence of the analysis, the interfacial fracture energy is the
key parameter governing the CNT pull-out strength and ductility at bonding stage, and
the Young's modulus of the CNT has also great effect on the pull-out behavior of the
straight CNT. In case of the single curved CNT, while the ultimate pull-out force of the
curved CNT at sliding stage is governed by the initial sliding force when preexisting
normal force is relatively high, the ultimate pull-out force, when the preexisting normal
force is not significant, is increased linearly proportional to the curvature and the
Young's modulus of the CNT due to the additionally induced normal force by the
bending stiffness of the curved CNT
Proto-Model of an Infrared Wide-Field Off-Axis Telescope
We develop a proto-model of an off-axis reflective telescope for infrared
wide-field observations based on the design of Schwarzschild-Chang type
telescope. With only two mirrors, this design achieves an entrance pupil
diameter of 50 mm and an effective focal length of 100 mm. We can apply this
design to a mid-infrared telescope with a field of view of 8 deg X 8 deg. In
spite of the substantial advantages of off-axis telescopes in the infrared
compared to refractive or on-axis reflective telescopes, it is known to be
difficult to align the mirrors in off-axis systems because of their asymmetric
structures. Off-axis mirrors of our telescope are manufactured at the Korea
Basic Science Institute (KBSI). We analyze the fabricated mirror surfaces by
fitting polynomial functions to the measured data. We accomplish alignment of
this two-mirror off-axis system using a ray tracing method. A simple imaging
test is performed to compare a pinhole image with a simulated prediction.Comment: 14 pages, 16 figure
Design of a Pultruded GFRP Deck for Highway Bridges
This paper deals with the design and analysis of a GFRP deck for the highway bridges. Several cellular tube sections are assessed to obtain a viable cross-sectional profile of the deck. Two GFRP patterns are proposed and tested. Using the proposed deck profile and GFRP patterns, a GFRP deck for a prototype steel I-girder bridge is designed and presented in this paper
Numerical analysis of dielectric micro-particle motion in a fluid and electric field
We present numerical analysis of a coupled problem composed of fluidics,
electromagnetic and particle dynamics. The forces acting on the dielectric micro-particle
consist of a dielectrophoretic(DEP) force, drag force and gravitational force in the proposed
analysis model. DEP force and drag force are calculated using the distribution of the electric
field and fluid velocity field to analyze the characteristic of the micro-particle motion. The
forces exerted by each field are driving terms in the Newton’s equation for particle motion.
The designed particle separating device, which has the one inlet and the two outlets, is
simulated to validate proposed numerical scheme. The analysis results show the trace of the
micro-particles can be analyzed using the proposed numerical approach
Improving disclosure of medical error through educational program as a first step toward patient safety
Participantâs Response to medical errors. Description of data: Raw data of participantâs response to medical errors (3 clinical cases with different severity of error outcome), satisfaction and change after the education program. (XLSX 18 kb
Beyond slurry-cast supercapacitor electrodes: PAN/MWNT heteromat-mediated ultrahigh capacitance electrode sheets
Supercapacitors (SCs) have garnered considerable attention as an appealing power source for forthcoming smart energy era. An ultimate challenge facing the SCs is the acquisition of higher energy density without impairing their other electrochemical properties. Herein, we demonstrate a new class of polyacrylonitrile (PAN)/multi-walled carbon tube (MWNT) heteromat-mediated ultrahigh capacitance electrode sheets as an unusual electrode architecture strategy to address the aforementioned issue. Vanadium pentoxide (V2O5) is chosen as a model electrode material to explore the feasibility of the suggested concept. The heteromat V2O5 electrode sheets are produced through one-pot fabrication based on concurrent electrospraying (for V2O5 precursor/MWNT) and electrospinning (for PAN nanofiber) followed by calcination, leading to compact packing of V2O5 materials in intimate contact with MWNTs and PAN nanofibers. As a consequence, the heteromat V2O5 electrode sheets offer three-dimensionally bicontinuous electron (arising from MWNT networks)/ion (from spatially reticulated interstitial voids to be filled with liquid electrolytes) conduction pathways, thereby facilitating redox reaction kinetics of V2O5 materials. In addition, elimination of heavy metallic foil current collectors, in combination with the dense packing of V2O5 materials, significantly increases (electrode sheet-based) specific capacitances far beyond those accessible with conventional slurry-cast electrodes.ope
Hyaluronan- and RNA-binding deubiquitinating enzymes of USP17 family members associated with cell viability
BACKGROUND: Protein degradation by the ubiquitin system plays a crucial role in numerous cellular signaling pathways. Deubiquitination, a reversal of ubiquitination, has been recognized as an important regulatory step in the ubiquitin-dependent degradation pathway. RESULTS: While identifying putative ubiquitin specific protease (USP) enzymes that contain a conserved Asp (I) domain in humans, 4 USP17 subfamily members, highly homologous to DUB-3, have been found (USP17K, USP17L, USP17M, and USP17N), from human chorionic villi. Expression analysis showed that USP17 transcripts are highly expressed in the heart, liver, and pancreas and are expressed moderately in various human cancerous cell lines. Amino acid sequence analysis revealed that they contain the highly conserved Cys, His, and Asp domains which are responsible for the deubiquitinating activity. Biochemical enzyme assays indicated that they have deubiquitinating activity. Interestingly, the sequence analysis showed that these proteins, with exception of USP17N, contain the putative hyaluronan/RNA binding motifs, and cetylpyridinium chloride (CPC)-precipitation analysis confirmed the association between these proteins and intracellular hyaluronan and RNA. CONCLUSION: Here, we report that the overexpression of these proteins, with exception of USP17N, leads to apoptosis, suggesting that the hyaluronan and RNA binding motifs in these enzymes play an important role in regulating signal transduction involved in cell death
Dieulafoy's Lesion of Jejunum: Presenting Small Bowel Mass and Stricture
Dieulafoy's lesion is an uncommon cause of gastrointestinal bleeding. Hemorrhage occurs through mucosal erosion from an abnormally dilated submucosal artery. Although Dieulafoy's lesion is usually located in the stomach, it may occur anywhere in the gastrointestinal tract. We report here on a case of jejunal Dieulafoy's lesion presenting as a mass and short segment stricture on CT and enteroclysis
The Initial Extent of Malapposition in ST-Elevation Myocardial Infarction Treated with Drug-Eluting Stent: The Usefulness of Optical Coherence Tomography
PURPOSE: The aim of this study is to identify the extent of initial malapposition using optical coherence tomography (OCT) in ST-elevation myocardial infarctions (STEMI) treated with different types of drug-eluting stents (DES).
MATERIALS AND METHODS: Twenty four STEMI patients that underwent primary percutaneous coronary intervention (PCI) were enrolled. The OCT and intravascular ultrasound (IVUS) were performed within 72 hours after the primary PCI. Distances between the endo-luminal surface of the strut reflection and the vessel wall and the extent of malapposition were measured and analyzed.
RESULTS: Sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES) and zotarolimus-eluting stents (ZES) were deployed in 7 patients (29%), 7 patients (29%) and 10 patients (42%). In total, 4951 struts in 620 mm single-stent segments were analyzed (1463 struts in SES, 1522 in PES, and 1966 in ZES). In strut analysis by OCT, the incidence of malapposition was 17 % (860/4951) and in stent analysis by IVUS, malapposition rate was 21% (5/24). The malapposition rate of strut level using OCT in 5 patients who had malapposition in IVUS was significantly higher than the 19 of those who had not (32 +/- 5% vs. 12 +/- 6%, p = 0.001). In addition, the frequency of malapposition was also significantly different (28% in SES, 11% in PES, 10% in ZES, p = 0.001). The use of SES was an independent predictor of malapposed struts.
CONCLUSION: The incidence of malapposition using OCT was quite prevalent in STEMI after primary PCI with DES implantation and SES has especially higher rates of malapposition compared to other DESs.ope
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