7,668 research outputs found
Breaking an image encryption algorithm based on chaos
Recently, a chaos-based image encryption algorithm called MCKBA (Modified
Chaotic-Key Based Algorithm) was proposed. This paper analyzes the security of
MCKBA and finds that it can be broken with a differential attack, which
requires only four chosen plain-images. Performance of the attack is verified
by experimental results. In addition, some defects of MCKBA, including
insensitivity with respect to changes of plain-image/secret key, are reported.Comment: 10 pages, 4 figure
SiO and H2O Maser Observations of Red Supergiants in Star Clusters Embedded in the Galactic Disk
We present the result of radio observations of red supergiants in the star
cluster, Stephenson's #2, and candidates for red supergiants in the star
clusters, Mercer et al. (2005)'s #4, #8, and #13, in the SiO and HO maser
lines.The Stephenson's #2 cluster and nearby aggregation at the South-West
contain more than 15 red supergiants. We detected one at the center of
Stephenson's #2 and three in the south-west aggregation in the SiO maser line,
and three of these 4 were also detected in the H2O maser line. The average
radial velocity of the 4 detected objects is 96 km s^{-1}, giving a kinematic
distance of 5.5 kpc, which locates this cluster near the base of the
Scutum-Crux spiral arm. We also detected 6 SiO emitting objects associated with
the other star clusters. In addition, mapping observations in the CO J=1--0
line toward these clusters revealed that an appreciable amount of molecular gas
still remains around Stephenson's #2 cluster in contrast to the prototypical
red-supergiant cluster, Bica et al.'s #122. It indicates that a time scale of
gas expulsion differs considerably in individual clusters.Comment: high res. figures available at
http://www.nro.nao.ac.jp/~lib_pub/report/data/no674.pdf. PASJ 62, No.2 (2010,
April 25 issue) in pres
Morphology of the red rectangle proto-planetary nebula
Poster no. 94Using the 3D morpho-kinematic modeling software SHAPE, we have created a model of the Red Rectangle that naturally reproduces many exotic morphological features including the notorious "ladder rungs". © 2012 International Astronomical Union.published_or_final_versionThe IAU Symposium No. 283: 'Planetary Nebulae: an Eye to the Future', Puerto de la Cruz, Tenerife, Spain, 25-29 July 2011. In International Astronomical Union Proceedings, 2012, v. 7 n. S283, p. 410-41
Post Asymptotic Giant Branch Bipolar Reflection Nebulae: Result of Dynamical Ejection or Selective Illumination?
published_or_final_versio
A novel surface segmentation approach for robotic manipulator-based maintenance operation planning
This paper presents a novel approach to segmenting a three-dimensional surface map by considering the task requirements and the movements of an industrial robot manipulator. Maintenance operations, such as abrasive blasting, that are performed by a field robot manipulator can be made more efficient by exploiting surface segmentation. The approach in this paper utilises an aggregate of multiple connectivity graphs, with graph edges defined by task constraints, and graph vertices that correspond to small, maintenance-specific target surfaces, known as Scale-Like Discs (SLDs). The task constraints for maintenance operations are based on the characteristics of neighbouring SLDs. The combined connectivity graphs are analysed to find clusters of vertices, thus segmenting the surface map into groups of related SLDs. Experiments conducted in three typical bridge maintenance environments have shown that the approach can reduce garnet usage by 10%-40% and reduce the manipulator joint movements by up to 35%. © 2012 Elsevier B.V. All rights reserved
Breaking a Chaotic Cryptographic Scheme Based on Composition Maps
Recently, a chaotic cryptographic scheme based on composition maps was
proposed. This paper studies the security of the scheme and reports the
following findings: 1) the scheme can be broken by a differential attack with
chosen-plaintext, where is the size of
plaintext and is the number of different elements in plain-text; 2) the
scheme is not sensitive to the changes of plaintext; 3) the two composition
maps do not work well as a secure and efficient random number source.Comment: 9 pages, 7 figure
Identifying the Manipulative Mating Methods Associated with Psychopathic traits and BPD Features
Psychopathy and borderline personality disorder (BPD) traits are associated with coercion and manipulation within relationships. The authors investigated whether BPD traits were uniquely associated with manipulation for emotional closeness whereas psychopathy was used for the purpose of attaining physical closeness. A community sample (N = 164) reported on mating behaviors, psychopathic traits, and BPD traits. Hierarchical regressions were conducted to predict mating behaviors that would account for the overlap between psychopathy and BPD. Total psychopathic traits were associated with lower levels of relationship exclusivity, greater use of partner poaching, and perpetration of sexual coercion. Specifically, callousness and egocentricity were related to lower relationship exclusivity. BPD traits were associated with the use of mate retention strategies, mate poaching, and victimization in sexual coercion. These findings indicate that manipulative mating behaviors encompass tools to achieve sex and intimacy. Those with BPD traits use these tools for emotional closeness, whereas those with psychopathic traits use them to obtain physical closeness and gratification
Collapse of the vortex-lattice inductance and shear modulus at the melting transition in untwinned
The complex resistivity of the vortex lattice in an
untwinned crystal of 93-K has been measured at frequencies
from 100 kHz to 20 MHz in a 2-Tesla field ,
using a 4-probe RF transmission technique that enables continuous measurements
versus and temperature . As is increased, the inductance increases steeply to a cusp
at the melting temperature , and then undergoes a steep collapse
consistent with vanishing of the shear modulus . We discuss in detail
the separation of the vortex-lattice inductance from the `volume' inductance,
and other skin-depth effects. To analyze the spectra, we consider a weakly
disordered lattice with a low pin density. Close fits are obtained to
over 2 decades in . Values of the pinning parameter
and shear modulus obtained show that collapses by
over 4 decades at , whereas remains finite.Comment: 11 pages, 8 figures, Phys. Rev. B, in pres
Class II ADP-ribosylation factors are required for efficient secretion of Dengue viruses
This article is available open access through the publisher’s website.Identification and characterization of virus-host interactions are very important steps toward a better understanding of the molecular mechanisms responsible for disease progression and pathogenesis. To date, very few cellular factors involved in the life cycle of flaviviruses, which are important human pathogens, have been described. In this study, we demonstrate a crucial role for class II Arf proteins (Arf4 and Arf5) in the dengue flavivirus life cycle. We show that simultaneous depletion of Arf4 and Arf5 blocks recombinant subviral particle secretion for all four dengue serotypes. Immunostaining analysis suggests that class II Arf proteins are required at an early pre-Golgi step for dengue virus secretion. Using a horseradish peroxidase protein fused to a signal peptide, we show that class II Arfs act specifically on dengue virus secretion without altering the secretion of proteins through the constitutive secretory pathway. Co-immunoprecipitation data demonstrate that the dengue prM glycoprotein interacts with class II Arf proteins but not through its C-terminal VXPX motif. Finally, experiments performed with replication-competent dengue and yellow fever viruses demonstrate that the depletion of class II Arfs inhibits virus secretion, thus confirming their implication in the virus life cycle, although data obtained with West Nile virus pointed out the differences in virus-host interactions among flaviviruses. Our findings shed new light on a molecular mechanism used by dengue viruses during the late stages of the life cycle and demonstrate a novel function for class II Arf proteins.Research Fund for Control of Infectious Diseases of Hong Kong and BNP Paribas Corporate and Investment Banking
A haptic base human robot interaction approach for robotic grit blasting
This paper proposes a remote operation method for a robot arm in a complex environment by using the Virtual Force (VF) based approach. A virtual robot arm is manipulated by a steering force, at the end-effecter, which is generated according to the movement of a feedback haptic. A three-dimensional force field (3D-F2) is employed in collision detection and avoidance. Repulsive forces from the 3D-F2 are produced and feedback to the haptic device that enables the operator to have a sense of touch on the encountered obstacle and then steer the arm to avoid it. As a result, collision-free poses of the virtual robot arm can then be used to command the real robot. Experiments are conducted in a mock up bridge environment where the real robot arm is steered to target points by the operator. Experiment results have shown successful collision avoidance and emulation of the actual command force and the virtual forces in remote operations
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