TCP CERL+: revisiting TCP congestion control in wireless networks with random loss

Wireless Networks - In this paper, we analyze the performance of wireless networks subject to random loss. In this regard, we revisit our TCP Congestion Control Enhancement for Random Loss (CERL)...     

The study of welded semi‐rigid connections in fire

Considering the deterioration of steel properties by temperature increase and the importance of the influence of connection behavior on the behavior of steel structures, we find that the exact understanding of the behavior of a specific steel connection in fire as well as the information about the effect of fire on the principal constitutive characteristics of the connection is necessary for safe design against fire. Thus, in this paper, the behavior of welded angle connections is studied at elevated temperatures using the abaqus finite element software. Steel members and connection components are considered to behave nonlinearly; the degradation of steel properties with increasing temperature is considered according to EC3, BS5950 recommendations. The results of finite element and experimental tests conducted on welded angle connections are compared, and the obtained failure modes and moment–rotation–temperature characteristics are in good agreement with those associated with the experimental tests. In the following, since the knowledge about moment–temperature–rotation behavior of a specific connection is needed for a fire‐resistant design, these properties are accurately determined, and finally, the effect of some parameters such as the moment applied on beam, change of column axial force and change of beam shear force on the stiffness of these connections at elevated temperatures is determined. Copyright © 2011 John Wiley & Sons, Ltd.     

Production of surface-active sophorolipid biosurfactant and crude oil degradability by novel Rhodotorula mucilaginosa strain SKF2

Biosurfactants are produced by important types of microorganisms such as bacteria, yeast, and filamentous fungi and have been used in a variety of industries. Among the 15 crude oil-degrading fungi, the two molds and one yeast were identified by 18S rDNA sequences as Mucor circinelloides strain SKMC, Fusarium fujikuroi strain DB2, and Rhodotorula mucilaginosa strain SKF2. These strains were isolated from crude oil–contaminated soil, diesel oil–contaminated soil, and activated sludge in the Oil Refinery Plant in Isfahan, Iran, respectively. The yeast strain was identified as a novel crude oil–degrading and biosurfactant-producing fungi in the presence of (1% v/v) Iranian light crude oil in the minimal salt medium (MSM). The highest amount of the dry weight of produced biosurfactant was measured at 6.2 g L⁻¹. Chemical nature of produced biosurfactant was determined as a surface-active sophorolipid biosurfactant compound by thin-layer chromatography, Fourier transform infra-red spectroscopy, and gas chromatography–mass spectrometry (GC–MS) analysis. The residual hydrocarbons in the MSM were analyzed by GC–MS, and it was shown that octadecane and docosane were eliminated by this novel strain completely.     

不同螺栓布置下螺栓连接的滞回性能

从1994年北岭地震中可看到,栓焊节点的抗震性能较差。因此,常用于工业建筑和高层建筑中的抗弯框架多采用端板连接和T型螺栓连接。采用有限元方法,通过改变螺栓的纵横布置对比了14个试件的滞回性能。结果表明:假定两者总的耗能能力相同,则T型螺栓连接的抗弯能力和初始转动刚度均比基于AISC规范设计的端板螺栓连接高。在往复荷载作用下,螺栓布置的改变对T型螺栓连接破坏模式的影响要大于端板连接,端板连接更适用于具有初始几何缺陷的结构。     

Contributions of automatic and controlled processes to the analysis of hierarchical structure.

Three experiments provide evidence that 2 mechanisms, 1 automatic and 1 controlled, produce variations in the efficiency with which local and global forms are processed. Targets are identified faster if they appear at the same level (global or local) as the target on the previous trial. M. R. Lamb, B. London, H. M. Pond, and K. A. Whitt (see record 1997-39043-003) provided evidence that the beneficial effect of level repetition is due to an automatic process that is outside voluntary control. In the present experiments, pretrial cues informed participants as to the level of the upcoming target. Valid cues benefited performance, whereas invalid cues harmed performance relative to noninformative neutral cues. This was so even when the relation between the cue and the level it signaled was arbitrary, indicating that the cues initiated voluntary shifts of attention. The benefit associated with level repetition, however, was unaffected by the cues. These data suggest that the benefit of level repetition results from a process that is not subject to voluntary control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Expression of pro form of prostate-specific antigen by mammalian cells and its conversion to mature, active form by human kallikrein 2

To study the expression, biosynthesis, and processing of prostate-specific antigen (PSA) in mammalian cells, recombinant PSA was expressed in Syrian hamster tumor cell line AV12-664 (AV12-PSA). Expression of PSA was monitored by the Tandem-MP PSA assay. PSA was secreted into the medium during the logarithmic phase of cell growth at >9 microg/ml and was stable. The PSA purified from spent medium of AV12-PSA cells did not exhibit any enzymatic activity and did not complex with the protease inhibitor, alpha-1-antichymotrypsin. These findings indicated that an inactive form of PSA was expressed by AV12-PSA cells. NH2-terminal sequencing confirmed the identity of the PSA purified from the spent medium of AV12-PSA cells to be pro-PSA. This demonstrates that PSA is expressed as pro-PSA by mammalian cells and suggests that pro-PSA may be present in biological fluids. Human kallikrein 2 (hK2), another member of the hK family, is also expressed predominantly in prostate epithelium. Although hK2 has been shown to exhibit trypsin-like activity, little is known about its natural substrates. Using purified proteins, we show that hK2 can convert pro-PSA to mature, enzymatically active PSA, thus establishing a physiological connection between hK2 and PSA. These findings imply that hK2 may be regulating PSA activity in vivo.     

Behaviour of welded top-seat angle connections exposed to fire

Beam-to-column connections have been found to significantly influence the structural behaviour at ambient and elevated temperatures. When steel-framed structures are exposed to fire, the load-bearing capacity is decreased and the behaviour of the joints is of particular concern. To account for the extensive applications of welded connections, eight experimental tests were carried out in this study on two different types of beam-to-column angle connections to investigate their fire resistance capacity. Failure characteristics and fracture modes of specimens were studied, and results are presented in the form of temperature–rotation curves. In addition, the influence of different parameters such as thickness of the angles, the value of the applied moment, and other geometrical and mechanical characteristics of the connections was investigated.     

Effect of fatigue loading on wicking properties of polyamide 66 nanofiber yarns

The wicking phenomenon is of prime importance with regards to biomedical applications of nanofiber yarns such as suture yarns and tissue scaffolds. In such applications, the yarns are usually subjected to cyclic tensile forces and biological tensile stresses. There is a lack of science behind the effect of fatigue on wicking properties of nanofiber yarns and this work aims at exploring this venue. Wicking properties of polyamide 66 nanofiber yarns are investigated by tracing the color change in the yarn structure resulting from pH changes during the capillary rise of distilled water. Results show that applying cyclic loading increases equilibrium wicking height in the Lucus–Washburn equation, which is attributed to changes in the overall pore structure in the cyclic loaded yarn. The likely causes of these changes are studied by scanning electron microscope, which reveals disentangled, more or less aligned and parallel nanofibers with a smaller radius in the nanofibrous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47206.     

Plastic Analysis of Braced Frames by Application of Metaheuristic Optimization Algorithms

The plastic analysis of moment frames by the combination of elementary mechanisms is one of the classic problems in the field of nonlinear analysis of stru     

Opto-electronic and antibacterial activity investigations of mono-dispersed nanostructure copper oxide prepared by a novel method: reduction of reactive oxygen species (ROS)

A novel approach for synthesis of copper oxide nanoparticles is reported by separation of nucleation and growth. The nano-material was characterized by X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and UV–Vis diffuse reflectance spectroscopy, transmission electron microscopy, atomic force microscopy, and Brunauer–Emmett–Teller analyses. Optical analysis of mono-dispersed nanostructure copper oxide by UV–Vis diffused reflectance spectroscopy showed the band gap value of 1.47 eV with a blue-shift in the optical band gap due to quantum confinement effect. The dynamic light scattering and zeta potential results showed fairly narrow size distribution and colloidal stability. The results showed that nano-particles were mono-dispersed spheres of 8 nm with no aggregation. Cell viability of treated murine fibroblast cell line (L-929) treated by different concentrations of nanoparticles showed significant viability up to 96% at concentrations 15 and 30 μg ml^?1. The nanoparticles exhibited outstanding and stable antibacterial activity against Staphylococcus aureus ATCC 6538 at 30 µg ml^?1. The viability and reactive oxygen species (ROS) generation in the L-929 cell line indicated that the nanoparticles were not toxic at the concentrations which were effective on bacteria. ROS analysis using DCFH-DA probe on L-929 were exposed to 7.5–60 μg ml^?1 of copper oxide nanoparticles in 6 h revealed ROS generation was decreased dramatically compare to the untreated cells and positive control.