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Do you have the tools to address recent challenges and problems in modern computer networks? Discover a unified view of auction theoretic applications and develop auction models, solution concepts, and algorithms with this multidisciplinary review. Devise distributed, dynamic, and adaptive algorithms for ensuring robust network operation over time-varying and heterogeneous environments, and for optimizing decisions about services, resource allocation, and usage of all network entities. Topics including cloud networking models, MIMO, mmWave communications, 5G, data aggregation, task allocation, user association, interference management, wireless caching, mobile data offloading, and security. Introducing fundamental concepts from an engineering perspective and describing a wide range of state-of-the-art techniques, this is an excellent resource for graduate and senior undergraduate students, network and software engineers, economists, and researchers.
This chapter examines how computers and smartphones are used with (or instead of) face-to-face (F2F) interactions for relationship maintenance. After explicating two different definitions of the phrase “relationship maintenance,” we summarize research on the role of particular communication technologies in relationship maintenance. We argue that much contemporary relationship maintenance in romantic relationships occurs in mixed-media relationships, which occur when the “parties conduct in whole or in part through the use of multiple media, including F2F” (Parks). The primary focus of this chapter is on the maintenance of romantic relationships, yet we also review research on other types of relationships when the processes examined seem applicable to close relationships more broadly. We conclude with several important points for future research on relational maintenance and communication technologies, including recognizing that (a) even though technologies can help people maintain their relationships, they also can create burdens and problems; (b) the way people use technologies influences the effects of those technologies in relationships; (c) there is a need for more research on the specific behaviors using technologies in romantic relationships; and (d) even with the rise of communication technologies, face-to-face maintenance behaviors remain important.
We present details of on-wafer-level 16-term error model calibration kits used for the characterization of W-band circuits based on a grounded coplanar waveguide (GCPW). These circuits were fabricated on a thin gallium arsenide (GaAs) substrate, and via holes, were utilized to ensure single mode propagation (i.e., eliminating the parallel-plate mode or surface mode). To ensure the accuracy of the definition for the calibration kits, multi-line thru-reflect-line (MTRL) assistant standards were also fabricated on the same wafer and measured. The same wafer also contained passive and active devices, which were measured subject to both 16-term and conventional line-reflect-reflect-match calibrations. Measurement results show that 16-term calibration kits are capable of determining the cross-talk more accurately. Other typical calibration techniques were also implemented using the standards on the GCPW calibration kits, and were compared with the MTRL calibration using a passive device under test. This revealed that the proposed GCPW GaAs calibration substrate could be a feasible alternative to conventional CPW impedance standard substrates, for on-wafer measurements at W-band and above.
Sustainable Development Goal (SDG) 9 is centered on three main pillars: industry, infrastructure and innovation. With 8 targets and 12 indicators, SDG 9 will have multiple impacts on forests, forest-based livelihoods and forest-based economies. Drawing on a comprehensive literature review, we conclude that major trade-offs will exist between SDG 9 and SDG 15 (sustainable use of terrestrial ecosystems), especially if economic expansion and increasing planetary impacts remain coupled. More specifically, the implementation of Target 9.1 and its corresponding indicators (road, infrastructure and transportation expansion) may lead to irreversible and widespread forest degradation and deforestation. As such, the short- and long-term environmental and social costs of this goal need to be better assessed, especially in light of the fact that other SDG 9 targets (e.g. small-scale industry expansion (Target 9.3); access to information and communications technology (Target 9.c)) may have diverse consequences for forests and livelihoods, depending on how they are applied. We call for reforms of SDG 9 to promote and support alternative socio-economic models that are not based on indefinite economic growth, nor reliant on the ongoing expansion of infrastructure, but, rather, necessitate forests and terrestrial ecosystem services to be essential building blocks of a green and sustainable economy.
Autocrats use repression to deter opposition. Are they successful in the long run? The author argues that state repression can have long-lasting alienating effects on citizens’ political attitudes and coercive effects on their political behavior. The article evaluates this proposition by studying the long-term effects of state terror during China's Cultural Revolution. It shows that individuals who grew up in localities that were exposed to more state-sponsored violence in the late 1960s are less trusting of national political leaders and more critical of the country's political system today. These anti-regime attitudes are more likely to be passed down to the younger generation if family members discuss politics frequently than if they do not. Yet while state repression has created anti-regime attitudes, it has decreased citizens’ contentious behavior. These findings highlight the dilemma that authoritarian rulers face when they seek to consolidate their rule through repression.
We report on the investigation of intermode beating mode-locked (IBML) pulse generation in a simple all-fiber Tm
-doped double clad fiber laser (TDFL). This IBML TDFL is implemented by matching longitudinal-mode frequency between 793 nm laser and TDFL without extra mode locker. The central wavelength of
, the fundamental pulse frequency of
and the signal-to-noise ratio (SNR) of
are achieved in this IBML TDFL. With laser cavity optimization, the IBML TDFL can finally generate an average output power of 1.03 W with corresponding pulse energy of
. These results can provide an easily accessible way to develop compact large-energy, high-power TDFLs.
We report on the study of single-mode fiber-laser-pumped mode-locked Yb:CALYO lasers via using a passive saturable absorber and Kerr-lens mode-locking technique, respectively. Up to 3.1-W average power with 103-fs pulse duration is obtained from the passive mode-locking, and down to 36-fs pulse duration with more than 2-W average power is achieved by the pure Kerr-lens mode-locking, which is to the best of our knowledge, the highest average power from a reported sub-40-fs Yb-based solid-state oscillator.
Autonomous ships are gaining in importance and are expected to shape the future of the global shipping industry. This evolutionary shift raises serious issues about compliance with the International Regulations for Preventing Collisions at Sea 1972 (COLREGs). This paper reviews the literature on autonomous ships from the perspective of the obligations of good seamanship imposed by COLREGs. The authors conclude that to facilitate the introduction of autonomous ships, the application barriers presented by COLREGs need to be analysed. With this goal, this paper presents a perspective from navigational practice. Four nautical scientists and two deck officers were invited to give their opinions. The analysis indicates that COLREGs require further elaboration and amendments to eliminate uncertainty of interpretation. In particular, the paper highlights the need to amend the ‘look-out’ rule (COLREGs Rule 5) to permit look-out by ‘computer vision’ alone while, at the same time, preserving the distinction between vessels navigating in restricted visibility and in sight of one another.
This study seeks to identify healthcare utilization patterns following symptomatic respiratory tract infections (RTIs) and the variables that may influence these patterns.
RTIs are responsible for the bulk of the primary healthcare burden worldwide. Yet, the use of health services for RTIs displays great discrepancies between populations. This research examines the influence of social demographics, economic factors, and accessibility on healthcare utilization following RTIs.
Structured interviews were administered by trained physicians at the households of informants selected by cluster randomization. Descriptive and multivariate binary logistic regression analysis was performed to assess healthcare utilization and associated independent variables.
A total of 60 678 informants completed the interviews. Of the 2.9% informants exhibiting upper RTIs, 69.5–73.9% sought clinical care. Healthcare utilization rates for common cold, influenza, nine acute upper RTIs, and overall RTIs demonstrate statistically significant associations with the variables of age, type of residence, employment, medical insurance, annual food expenditure, distance to medical facilities, and others. The odds ratios for healthcare utilization rates varied substantially, ranging from 0.026 to 9.364. More than 69% of informants with RTIs sought clinical interventions. These findings signify a marked issue with the large amount of healthcare for self-limited RTIs.
The regular reflection to Mach reflection (
) transition in inviscid perfect air for shock reflection over convex and straight wedges is investigated. Provided that the variation of shock intensity only has a second-order effect on the wave transition, the possible cases for the occurrence of the
transition for curved shock reflection over a wedge are discussed. For a planar shock reflecting over a convex wedge, four different flow regions are classified and the mechanism of the disturbance propagation is interpreted. It is found that the flow-induced rarefaction waves exist between disturbances generated from neighbouring positions and isolate them. For a curved shock reflecting over a convex wedge, although the distributions of the flow regions are different from those in planar shock reflection, the analysis for the planar shock case can be extended to curved shock cases as long as the wedge is convex. When a diverging shock reflects off a straight wedge, the flow-induced rarefaction waves are absent. However, the disturbances generated earlier cannot overtake the reflection point before the pseudo-steady criterion is satisfied. In the cases considered, the flow in the vicinity of the reflection point will not be influenced by the unsteady flow caused by the shock intensity and the wedge angle variations. This is clearly a local property of the shock–wall interaction, no matter what the history of the shock trajectory is. For validation, extensive inviscid numerical simulations are performed, and the numerical results show the reliability of the pseudo-steady criterion for predicting the
transition on a convex wedge.
Nitroethane (NE), 2-nitroethanol (NEOH) and 2-nitro-1-propanol (NPOH) were investigated in order to determine their inhibitory effects on in vitro ruminal fermentation and methane (CH4) production of a hay-rich substrate (alfalfa hay: maize meal = 4:1, w/w). The rumen liquor collected from cannulated Holstein dairy cows was incubated at 39 °C for 72 h. The addition of NE, NEOH and NPOH slowed down the fermentation process and notably decreased molar CH4 proportion by 96.8, 96.4 and 35.0%, respectively. The abundance of total methanogen and methanogens from the order Methanobacteriales were all decreased with NE, NEOH and NPOH supplementation. Meanwhile, the nitrocompound addition reduced mcrA gene expression, coenzyme F420 and F430 contents. The correlation analysis showed that CH4 production was correlated positively with the population abundance of total methanogens, Methanobacteriales, mcrA gene expression, coenzyme contents of F420 and F430. The nitrocompound addition decreased acetate concentration and increased propionate and butyrate concentrations in the culture fluid. In summary, both NE and NEOH addition presented nearly the same inhibitory effectiveness on in vitro CH4 production; they were more effective than NPOH. The results of the current study provide evidence that NE, NEOH and NPOH can dramatically decrease methanogen population, mcrA gene expression and the coenzyme content of F420 and F430 in ruminal methanogenesis.
The nutritional intake of Tibetan sheep on the harsh Qinghai-Tibetan Plateau (QTP) is often under maintenance requirements, especially during the long, cold winter. However, they have adapted well and even thrive under these conditions. The aim of this study was to gain insight into how the rumen epithelium of Tibetan sheep has adapted to the consumption of low energy level diets. For this purpose, we compared Tibetan and Small-tailed Han sheep (n = 24 of each breed, all wethers and 1.5 years of age), which were divided randomly into one of four groups and offered ad libitum diets of different digestible energy (DE) densities: 8.21, 9.33, 10.45 and 11.57 MJ DE/kg dry matter (DM). The Tibetan sheep had higher rumen concentrations of total SCFAs, acetate, butyrate and iso-acids but lower concentrations of propionate than Small-tailed Han sheep. The Tibetan sheep had higher absorption capability of SCFAs due to the greater absorption surface area and higher mRNA expression of the SCFAs absorption relative genes than Small-tailed Han sheep. For the metabolism of SCFAs in the rumen epithelium, the Small-tailed Han sheep showed higher utilization of the ketogenesis pathway than Tibetan sheep, however, Tibetan sheep had greater regulation capacity in SCFAs metabolism pathways. These differences between breeds allowed the Tibetan sheep to have greater capability of absorbing SCFAs and better capacity to regulate the metabolism of SCFAs, which would allow them to cope with low energy intake better than Small-tailed Han sheep.
The synergetic effects of surface smoothing exhibited during the inductively coupled plasma reactive ion etching (ICP-RIE) of free-standing polycrystalline diamonds (PCDs) were investigated. Changing the assistive gas types generated variable surface oxidation states and chemical environments that resulted in different etching rates and surface morphologies. The main reaction bond mechanism (C–O) during ICP-RIE and the ratio of C–O–C/O–C=O associated with the existence of a uniform smooth surface with root mean square (RMS) roughness of 2.36 nm were observed. An optimal process for PCD smoothing at high etching rate (4.6 μm/min) was achieved as follows: 10% gas additions of CHF3 in O2 plasma at radio frequency power of 400 W. The further etched ultra-smooth surface with RMS roughness <0.5 nm at etching rate of 0.23 μm/min that being produced by transferring this optimum recipe on single crystal diamonds with surface patterns confirmed the effectiveness of the fast smoothing approach and its feasibility for diamond surface patterning.
In order to develop an efficient and accurate quasi-continuum approach for contact problems of low-dimensional nanoscale carbon materials, a van der Waals contact-bond model is proposed in this study. This method can involve the important information of nano- and micro-structures, such as the bonded carbon atom interactions and the long-range van der Waals effect, which is usually homogenized and neglected in continuum methods. The degree of freedom of the atomic systems can be reduced dramatically; therefore, the model is beneficial for rapid simulations and large-scale computations of carbon nano-components. The so-called higher-order Cauchy–Born rule is used to establish the geometrically consistent constitutive model, and a meshless local Petrov–Galerkin-based computational framework is constructed for the mechanical responses of carbon nanoscale systems. The stiffness matrix is derived analytically, and the incremental governing equation is solved with the Newton–Raphson iteration method. Consequently, this method is much faster than order-N2 approaches such as molecular dynamic simulation.
Standardizing healthcare surface sampling requires the evaluation of sampling tools for organism adherence. Here, 7 sampling tools were evaluated to assess their elution efficiencies in the presence of 5 pathogens. Foam sponges (80.6%), microfiber wipes (80.5%), foam swabs (77.9%), and cellulose sponges (66.5%) yielded the highest median elution efficiencies.
Current understanding of turbulence modulation by solid particles is incomplete as making reliable predictions on the nature and level of modulation remains a challenging task. Multiple modulation mechanisms may be simultaneously induced by particles, but the lack of reliable methods to identify these mechanisms and quantify their effects hinders a complete understanding of turbulence modulation. In this work, we present a full analysis of the turbulent kinetic energy (TKE) equation for a turbulent channel flow laden with a few fixed particles near the channel walls, in order to investigate how the wall generated turbulence interacts with the particles and how, as a result, the global turbulence statistics are modified. All terms in the budget equations of total and component-wise TKEs are explicitly computed using the data from direct numerical simulations. Particles are found to modify turbulence by two competing mechanisms: the reduction of the intrinsic turbulence production associated with a reduced mean shear due to the resistance imposed by solid particles (the first mechanism), and an additional TKE production mechanism by displacing incoming fluid (the second mechanism). The distribution of TKE in the wall-normal direction is also made more homogeneous due to the significantly enhanced pressure transport of TKE. Finally, the budget analysis of component-wise TKE reveals an enhanced inter-component TKE transfer due to the presence of particles, which leads to a more isotropic distribution of TKE among three velocity components.