SEQUENCE SYNCHRONIZATION IN A WIDEBAND CDMA SYSTEM

A mathematical model of a synchronization block of a DS-CDMA system is developed and then investigated using a simulation. For this synchronization a pilot sequence has been used that can be a pseudorandom sequence or a chaotic sequence of a limited length. The theoretical model is tested by simulation. It was shown that the system can be synchronized using a pilot sequence represented by a periodically repeated chaotic sequence

Frontline professionals in the age of institutional rearrangement: the case of needs assessment for public services

Session 3: Institutional rearrangement of the public domai

The effect of melatonin on bacterial translocation following ischemia/reperfusion injury in a rat model of superior mesenteric artery occlusion

Background: Acute mesenteric ischemia is a life-threatening vascular emergency resulting in tissue destruction due to ischemia-reperfusion injury. Melatonin, the primary hormone of the pineal gland, is a powerful scavenger of reactive oxygen species (ROS), including the hydroxyl and peroxyl radicals, as well as singlet oxygen, and nitric oxide. In this study, we aimed to investigate whether melatonin prevents harmful effects of superior mesenteric ischemia-reperfusion on intestinal tissues in rats. Methods: Rats were randomly divided into three groups, each having 10 animals. In group I, the superior mesenteric artery (SMA) was isolated but not occluded. In group II and group III, the SMA was occluded immediately distal to the aorta for 60 minutes. After that, the clamp was removed and the reperfusion period began. In group III, 30 minutes before the start of reperfusion, 10 mg/kg melatonin was administered intraperitonally. All animals were sacrified 24 hours after reperfusion. Tissue samples were collected to evaluate the I/R-induced intestinal injury and bacterial translocation (BT). Results: There was a statistically significant increase in myeloperoxidase activity, malondialdehyde levels and in the incidence of bacterial translocation in group II, along with a decrease in glutathione levels. These investigated parameters were found to be normalized in melatonin treated animals (group III). Conclusion: We conclude that melatonin prevents bacterial translocation while precluding the harmful effects of ischemia/reperfusion injury on intestinal tissues in a rat model of superior mesenteric artery occlusion. © 2015 Ozban et al.; licensee BioMed Central

Relational job crafting: Exploring the role of employee motives with a weekly diary study

© The Author(s) 2018. In this weekly diary study, we integrated research on job crafting to explore the associations between expansion and contraction oriented relational job crafting, work engagement and manager-rated employee behaviours (work performance and voice). Furthermore, we investigated cross-level moderations of prosocial and impression management motives on our proposed associations. We tested our hypotheses with matched data collected over seven weeks in Istanbul, Turkey. The results from multilevel analyses revealed that (a) expansion oriented relational job crafting is positively related with work performance and voice via work engagement, while (b) contraction oriented relational job crafting is negatively related with work performance and voice via work engagement, all measured at the week level. Furthermore, impression management motives of employees moderated the association between expansion oriented relational job crafting and work engagement in that this positive association is stronger for employees low on impression management motives. Our results contribute to job crafting research in two ways. First, it focuses on relational job crafting and discusses how and why the two opposite types of relational job crafting (expansion versus contraction oriented) impact on work engagement and employees’ key outcomes in the way they do. This addresses the question ‘is there a dark side to job crafting?’ Second, it focuses on the importance of context and integrates two motives relevant to understand how relational job crafting unfolds, thereby taking a step to address questions for whom (i.e. what kinds of employees), relational job crafting is more effective and translates into enhanced (vs deteriorated) work outcomes. Moreover, our use of a weekly within-person design adds to a recently growing research stream emphasizing the dynamic nature of job crafting

De-noising 'Initial Condition Modulation' Wideband Chaotic Communication Systems with Linear & Wavelet Filters

In this paper de-noising techniques are investigated in connection with secure wideband chaotic communication systems. An alternate version of the recently proposed Ueda chaotic communication system based on the initial condition modulation (ICM) of the chaotic carrier by the binary message to be transmitted is proposed and evaluated in the presence of noise, demonstrating a significant improvement. It is then shown that the running average finite impulse response (FIR) filter, and the hard-threshold filtering techniques in Haar and Daubechies wavelet domain can be used to significantly improve the performance of the proposed chaotic communication system

Direct observation of optically induced transient structures in graphite using ultrafast electron crystallography

We use ultrafast electron crystallography to study structural changes induced in graphite by a femtosecond laser pulse. At moderate fluences of ~< 21mJ/cm^2, lattice vibrations are observed to thermalize on a time scale of ~8ps. At higher fluences approaching the damage threshold, lattice vibration amplitudes saturate. Following a marked initial contraction, graphite is driven nonthermally into a transient state with sp^3-like character, forming interlayer bonds. Using ab initio density functional calculations, we trace the governing mechanism back to electronic structure changes following the photo-excitation.Comment: 5 pages, 4 figures; to appear in Phys. Rev. Let

Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?

Background: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties. Nevertheless, it was proven that, due to modest dispersion of nanoparticles, such high expectations often remain unmet. In this article, by introducing the notion of nanofin, a possible solution is envisioned, where nanostructures with high aspect-ratio are sparsely attached to a solid surface (to avoid a significant disturbance on the fluid dynamic structures), and act as efficient thermal bridges within the boundary layer. As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes. Results: Toward the end of implementing the above idea, we focus on single carbon nanotubes to enhance heat transfer between a surface and a fluid in contact with it. First, we investigate the thermal conductivity of the latter nanostructures by means of classical non-equilibrium molecular dynamics simulations. Next, thermal conductance at the interface between a single wall carbon nanotube (nanofin) and water molecules is assessed by means of both steady-state and transient numerical experiments. Conclusions: Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 W·m-2·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surface