A Cost-effective Shuffling Method against DDoS Attacks using Moving Target Defense

Moving Target Defense (MTD) has emerged as a newcomer into the asymmetric field of attack and defense, and shuffling-based MTD has been regarded as one of the most effective ways to mitigate DDoS attacks. However, previous work does not acknowledge that frequent shuffles would significantly intensify the overhead. MTD requires a quantitative measure to compare the cost and effectiveness of available adaptations and explore the best trade-off between them. In this paper, therefore, we propose a new cost-effective shuffling method against DDoS attacks using MTD. By exploiting Multi-Objective Markov Decision Processes to model the interaction between the attacker and the defender, and designing a cost-effective shuffling algorithm, we study the best trade-off between the effectiveness and cost of shuffling in a given shuffling scenario. Finally, simulation and experimentation on an experimental software defined network (SDN) indicate that our approach imposes an acceptable shuffling overload and is effective in mitigating DDoS attacks

Broadband surface-wave transformation cloak

Guiding surface electromagnetic waves around disorder without disturbing the wave amplitude or phase is in great demand for modern photonic and plasmonic devices, but is fundamentally difficult to realize because light momentum must be conserved in a scattering event. A partial realization has been achieved by exploiting topological electromagnetic surface states, but this approach is limited to narrow-band light transmission and subject to phase disturbances in the presence of disorder. Recent advances in transformation optics apply principles of general relativity to curve the space for light, allowing one to match the momentum and phase of light around any disorder as if that disorder were not there. This feature has been exploited in the development of invisibility cloaks. An ideal invisibility cloak, however, would require the phase velocity of light being guided around the cloaked object to exceed the vacuum speed of light—a feat potentially achievable only over an extremely narrow band. In this work, we theoretically and experimentally show that the bottlenecks encountered in previous studies can be overcome. We introduce a class of cloaks capable of remarkable broadband surface electromagnetic waves guidance around ultrasharp corners and bumps with no perceptible changes in amplitude and phase. These cloaks consist of specifically designed nonmagnetic metamaterials and achieve nearly ideal transmission efficiency over a broadband frequency range from 0+ to 6 GHz. This work provides strong support for the application of transformation optics to plasmonic circuits and could pave the way toward high-performance, large-scale integrated photonic circuits.National Natural Science Foundation (China) (Grant 61322501)National Natural Science Foundation (China) (Grant 61275183)National Top-Notch Young Professionals Program (Grant FANEDDC-200950)Program for New Century Excellent Talents (NCET-12-0489)Fundamental Research Funds for the Central Universities (Grant FRFCU-2014XZZX003-24)Nanyang Assistant Professorship Start-Up GrantSingapore. Ministry of Education (Grant Tier 1 RG27/12)Singapore. Ministry of Education (Grant MOE2011-T3-1-005)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (Contract W911NF-13-D-0001)United States. Dept. of Energy (Solid-State Solar-Thermal Energy Conversion Center Grant de-sc0001299

Optimization of Processing Parameters and Microstructure Evolution of (TiB+La2O3)/Ti6Al4V Manufactured by Laser Melting Deposition

Due to the intrinsically ultrahigh cooling rate and thermal gradient during laser melting deposition (LMD), columnar-to-equiaxed transition (CET) of grains has been a significant challenge in titanium-based alloys. In this study, two strategies, including the optimization of processing parameters and the addition of ceramics particles, were utilized to promote the CET of Ti6Al4V. The optimal processing parameters of Ti6Al4V were confirmed by response surface methodology (RSM). The width of prior β grains effectively decreases under the minimum dilution of single track. Besides, different contents of TiB2 and La2O3 were added to Ti6Al4V powder and the in situ (TiB+La2O3)/Ti6Al4V composites were manufactured using the identified optimal processing parameters. In situ TiB whiskers segregating at the grain boundaries tailor the coarse columnar to equiaxed grains with La2O3 particles dispersed in the composites. With increasing formation of the reinforcements, equiaxed grain size decreases from 23.3 to 11.9 μm. The ultimate tensile strength of the components was improved by 19.6% and 26.4% compared to that of Ti6Al4V. This work provides systematic solutions to suppress the coarse columnar grains and refine the microstructure for titanium-based alloys.publishedVersio

Autonomy support in telehealth: an evolutionary concept analysis

AimsAutonomy support plays a critical role in safeguarding patients’ fundamental rights and promoting health behaviors. The context of autonomy support is transitioning from traditional face-to-face healthcare settings to telehealth, leading to an evolution in the connotation of autonomy support. This study aimed to clarify the connotation of autonomy support in telehealth and to develop a conceptual framework to guide innovations in clinical practice and the advancement of related theories.MethodsRodgers’ evolutionary method was used to clarified attributes, antecedents, and consequences of autonomy support in telehealth. The integrative review strategy of Whittemore and Knafl was used as the methodology for searching relevant literature.ResultsTwenty-five articles were included. The attributes were identified as: (i) technical feedback; (ii) virtual agent; (iii) choice; (iv) rationale; (v) empathy; (vi) collaboration; and (vii) strengths. The antecedents were: (i) telehealth service system; (ii) change in awareness toward autonomy support; and (iii) patient preference of needs for autonomy. The consequences were: (i) multidimensional perception; (ii) emotional experience; (iii) health behavior; (iv) social relation; and (v) technological dependence.ConclusionThis study clarified the attributes, antecedents, and consequences of autonomy support in telehealth, developing and improving a conceptual framework for autonomy support. These findings will provide a theoretical foundation for developing technology-enabled autonomy support strategies in telehealth practice, better adapting to the emerging needs of patients in the context of the digital age

Promoting cellulase and hemicellulase production from Trichoderma orientalis EU7-22 by overexpression of transcription factors Xyr1 and Ace3.

The construction of hyper-production strains of cellulase is the prerequisite for the production of biofuels or biochemicals. Trichoderma orientalis EU7-22 with complete cellulase system shows the potential for cellulase production in industrial scale. To improve the cellulase production, two crucial transcription activators Xyr1 and Ace3 were constitutively overexpressed in EU7-22 strain. Cellulase, xylanase and protein secretion were significantly improved in the recombinant strain dxyA-8 under inducing culture, which were 2.34, 0.68 and 1.06 folds higher than those of EU7-22, respectively. Moreover, the FPase and CMCase activities were up to 2.55 IU/mL and 90.38 IU/mL with glucose as carbon source, which were 2.12 and 1.95 folds higher than those of EU7-22 under inducing condition, respectively. Reducing sugar released from pretreated spartina that hydrolyzed by crude enzyme from dxyA-8 had achieved 24% improvement. Therefore, overexpression of these transcription factors effectively promotes the production of cellulase and hemicellulase of Trichoderma orientalis EU7-22

Promoting cellulase and hemicellulase production from Trichoderma orientalis EU7-22 by overexpression of transcription factors Xyr1 and Ace3

Abstract(#br)The construction of hyper-production strains of cellulase is the prerequisite for the production of biofuels or biochemicals. Trichoderma orientalis EU7-22 with complete cellulase system shows the potential for cellulase production in industrial scale. To improve the cellulase production, two crucial transcription activators Xyr1 and Ace3 were constitutively overexpressed in EU7-22 strain. Cellulase, xylanase and protein secretion were significantly improved in the recombinant strain dxyA-8 under inducing culture, which were 2.34, 0.68 and 1.06 folds higher than those of EU7-22, respectively. Moreover, the FPase and CMCase activities were up to 2.55 IU/mL and 90.38 IU/mL with glucose as carbon source, which were 2.12 and 1.95 folds higher than those of EU7-22 under inducing condition, respectively. Reducing sugar released from pretreated spartina that hydrolyzed by crude enzyme from dxyA-8 had achieved 24% improvement. Therefore, overexpression of these transcription factors effectively promotes the production of cellulase and hemicellulase of Trichoderma orientalis EU7-22

Effect of Supplementation with Bacillus subtilis in the Diet of Pigs on Protein and Lipid Oxidation of Pork Stored in High-oxygen Modified Atmosphere Packaging

To investigate the effect of dietary addition of Bacillus subtilis on the antioxidant capacity, meat color, protein oxidation, lipid oxidation and sensory quality of pork during storage in high-oxygen modified atmosphere packaging, 12 Duroc × Landrace × Yorkshire pigs were equally allocated into 2 groups that were fed a basal diet alone and in combination with B. subtilis, respectively. Following slaughter, the longissimus dorsi muscle was taken and cut into two parts: one part was used to measure the activity of antioxidant enzymes; the other part was packaged under high oxygen conditions and stored at 4 ℃. The meat color and the contents of malondialdehyde (MDA), carbonyl, and sulfhydryl were measured after 0, 5, 10, 15, and 20 d, and sensory evaluation was performed. The results demonstrated that the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) significantly increased in the B. subtilis supplementation group compared with those in the control group (P < 0.05). Furthermore, dietary supplementation with B. subtilis significantly improved the color of pork stored in high-oxygen modified atmosphere packaging (P < 0.05). During low-temperature storage, dietary supplementation with B. subtilis decreased the MDA content (P < 0.05) and inhibited the lipid oxidation of pork stored in high-oxygen modified packaging. In addition, it significantly inhibited the formation of carbonyl compounds and the loss of sulfhydryl compounds (P < 0.05), and significantly increased the sensory color score of high-oxygen modified atmosphere packaged pork and the overall preference score after opening the package (P < 0.05). In summary, dietary addition of B. subtilis could improve the antioxidant capacity of pork, thereby maintaining the color and inhibiting protein and lipid oxidation in pork stored in high-oxygen modified atmosphere packaging, ultimately enhancing the eating quality of pork