861 research outputs found
Entropic competition in polymeric systems under geometrical confinement
Using molecular dynamics simulation, we investigate the effect of confinement
on a system that comprises several stiff segmented polymer chains where each
chain has similar segments, but length and stiffness of the segments vary among
the chains which makes the system inhomogeneous. The translational and
orientational entropy loss due to the confinement plays a crucial role in
organizing the chains which can be considered as an entropy-driven segregation
mechanism to differentiate the components of the system. Due to the
inhomogeneity, both weak and strong confinement regimes show the competition in
the system and we see segregation of chains as the confining volume is
decreased. In the case of strong spherical confinement, a chain at the
periphery shows higher angular mobility than other chains, despite being more
radially constrained.Comment: 16 pages, 11 figure
Catalytic decomposition of 2-chlorophenol using an ultrasonic-assisted Fe3O4-TiO2@MWCNT system: Influence factors, pathway and mechanism study.
As a reusable sonocatalyst, magnetically separable Fe3O4-TiO2@MWCNT (FMT) was synthesized by an ultrasound-assisted wet impregnation method and was evaluated in the removal of 2-chlorophenol (2CP). Physical and chemical properties of the catalyst composite materials were investigated by all catalysts were systematically characterized using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray Analysis (EDX), Dynamic light scattering (DLS), and N2-physisorption. The efficiency and kinetics of 2CP removal by FMT-assisted sonocatalysis (FMT-US) was systematically investigated under various operational parameters i.e. pH, FMT and 2CP concentration, temperature and ultrasonic power. The results indicated that 0.4gL-1 FMT dosage, pH 5, temperature of 35°C as well as 50 w ultrasound power are the most favorable conditions for the degradation of the 2CP. Furthermore, both of the superoxide and hydroxyl radicals were produced in the reaction, however, superoxide radicals were assumed to be the dominating reactive species for the 2CP degradation, according to the scavenging tests and electron paramagnetic resonance tests. Moreover, the FMT catalyst exhibited a high reusability and stability in the US/FMT system during the five repetitive experiments. The intermediate products were identified by GC-MS, thereby a possible degradation pathway is proposed. The chemical oxygen demand (COD) and corresponding total organic carbon (TOC) removal efficiencies were 64.9% and 56.7%, respectively. Finally, toxicity tests showed that the toxicity of the solution increased during the first 5min and then decreased significantly with the progress of the oxidation. The mechanisms of ultrasound irritation enhanced FMT activation were also proposed.
Copyright © 2017 Elsevier Inc. All rights reserved
A Survey of Air-to-Ground Propagation Channel Modeling for Unmanned Aerial Vehicles
In recent years, there has been a dramatic increase in the use of unmanned
aerial vehicles (UAVs), particularly for small UAVs, due to their affordable
prices, ease of availability, and ease of operability. Existing and future
applications of UAVs include remote surveillance and monitoring, relief
operations, package delivery, and communication backhaul infrastructure.
Additionally, UAVs are envisioned as an important component of 5G wireless
technology and beyond. The unique application scenarios for UAVs necessitate
accurate air-to-ground (AG) propagation channel models for designing and
evaluating UAV communication links for control/non-payload as well as payload
data transmissions. These AG propagation models have not been investigated in
detail when compared to terrestrial propagation models. In this paper, a
comprehensive survey is provided on available AG channel measurement campaigns,
large and small scale fading channel models, their limitations, and future
research directions for UAV communication scenarios
Populist communication in the new media environment: a cross-regional comparative perspective
The changing terms of mediation place new demands, opportunities and risks on the performance of the political persona. Visibility has become a double-edged sword, leaving representatives vulnerable to exposure while new tools provide opportunities for emerging entrepreneurial actors. This double risk to elites’ mediated personas—exposure and challenge from entrepreneurs—renders their armour of authenticity dangerously fragile, which nourishes a public sense of being inefficaciously represented. It is this climate in which populism currently flourishes around the globe. Three primary criteria of mediated self-representation by politicians—visibility, authenticity and efficacy—form the focus of this paper: how do populists negotiate such demands in different democratic contexts, and wherein lies the symbiosis between populism and the new media environment suggested by the literature? To answer this, the paper compares two populist cases responding to different democratic contexts: UKIP, a right-wing party from an established democracy (UK), and the Economic Freedom Fighters (EFF), a left-wing party from a transitional democracy (South Africa). The objects of study are disruptive performances by these parties, which are considered emblematic manifestations of populist ideology as they establish a Manichaean relationship between the elite and populist actors who embody the people. The paper introduces disruption as a multi-faceted and significant analytical concept to explain the populist behaviour and strategies that underlie populist parties’ responses to the demands for visibility, authenticity and efficacy that the new media environment places upon political representatives. Using mixed methods with an interpretive focus, the paper paints a rich picture of the contexts, meanings and means of construction of populist performances
Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater
Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal
An Enhanced Adaptive Algorithm to Mitigate Mis-coordination Problem of the Third Zone of Distance Relays
ABSTRACT Cascaded tripping of power lines due to mal-operation of zone 3 distance relays is one of the main causes of many blackouts worldwide. The improved protection technique for zone 3 can help to prevent such mal-operation and, thus, more reliable power systems can be envisaged. This paper presents a novel zone-3 setting scheme based on impedance seen by distance relays in order to calculate zone-3 setting of the relays when faults are simulated on the reach of zone-2 of primary distance relays. The new technique is also enhanced to be used in an adaptive protection system. Since three phase fault rarely occurs in the system and in order to have better demonstration of effectiveness of the proposed scheme, it is tested for various type of faults such as, two phase (AB), single phase to ground (AG) and two phase to ground (ABG) as well as three-phase (ABC) using data simulated through DIgSILENT in the IEEE 30-bus test system during different topologies. The simulation results show that the novel zone 3 distance relay elements using the proposed method operate correctly for various events
Adaptive Fuzzy Synergetic PSS Design to Damp Power System Oscillations
This paper presents a novel indirect adaptive Power System Stabilizer (PSS) via a developed synergetic control methodology and fuzzy systems. Fuzzy system is utilized in an adaptive scheme to estimate the system using a nonlinear model. The synergetic control guarantees robustness of the controller and makes the controller easy to implement because of using a chatter free continuous control law. Additionally, the parameters of the controller are optimized by Imperialist Competitive Algorithm (ICA). The effectiveness of the proposed scheme is confirmed on a single machine power system while the stability is guaranteed through Lyapunov synthesis
Trauma-related emotions and radical acceptance in dialectical behavior therapy for posttraumatic stress disorder after childhood sexual abuse
Background: Posttraumatic Stress Disorder (PTSD) related to childhood sexual abuse (CSA) is often associated with a wide range of trauma-related aversive emotions such as fear, disgust, sadness, shame, guilt, and anger. Intense experience of aversive emotions in particular has been linked to higher psychopathology in trauma survivors. Most established psychosocial treatments aim to reduce avoidance of trauma-related memories and associated emotions. Interventions based on Dialectical Behavior Therapy (DBT) also foster radical acceptance of the traumatic event.
Methods: This study compares individual ratings of trauma-related emotions and radical acceptance between the start and the end of DBT for PTSD (DBT-PTSD) related to CSA. We expected a decrease in trauma-related emotions and an increase in acceptance. In addition, we tested whether therapy response according to the Clinician Administered PTSD-Scale (CAPS) for the DSM-IV was associated with changes in trauma-related emotions and acceptance. The data was collected within a randomized controlled trial testing the efficacy of DBT-PTSD, and a subsample of 23 women was included in this secondary data analysis.
Results: In a multilevel model, shame, guilt, disgust, distress, and fear decreased significantly from the start to the end of the therapy whereas radical acceptance increased. Therapy response measured with the CAPS was associated with change in trauma-related emotions.
Conclusions: Trauma-related emotions and radical acceptance showed significant changes from the start to the end of DBT-PTSD. Future studies with larger sample sizes and control group designs are needed to test whether these changes are due to the treatment.
Trial registration: ClinicalTrials.gov, number NCT0048100
Analysis of Nipple-Areola Complex Localization Using Male Cadavers: Considerations for Gender-Affirming Surgery
Background:
Masculinizing chest reconstruction is the most common gender-affirming surgery in transgender males. Despite the current literature’s acknowledgment of the vital role that proper placement of the nipple-areola complex (NAC) plays in a masculine chest contour, there is still much debate regarding the best anatomical landmarks to achieve the desired result.
Objectives:
The primary aim of this study is to determine which landmarks for NAC placement can be applied across diverse body types and aid surgeons in creating a masculine chest.
Methods:
Twenty-five formaldehyde-embalmed male cadavers were analyzed by conducting various measurements of the NAC, nipple, and surrounding bony and muscular landmarks to identify the most consistent landmarks for proper NAC placement. Linear regression analyses were run to determine how the distance between nipple to respective landmarks varied based on antemortem body mass index (BMI), height, weight, and age.
Results:
The measurements for the inferior and lateral borders of the pectoralis major muscle (PMM) displayed the least amount of variance of all the anatomical landmarks studied. Additionally, there was no significant change in these pectoral measurements with varying BMI, height, weight, or age, indicating that these measurements are reliable landmarks for NAC placement across various body types. The average NAC placement in relation to the inferior and lateral borders of PMM was around 2.5 and 2.0 cm, respectively.
Conclusions:
Our cadaveric analysis indicates that aesthetically pleasing masculine chest results can be produced consistently across varying body types when adhering to a simple pectoral approach in NAC placement
Global, regional, and national incidence, prevalence, and mortality of HIV, 1980–2017, and forecasts to 2030, for 195 countries and territories: a systematic analysis for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017
Background
Understanding the patterns of HIV/AIDS epidemics is crucial to tracking and monitoring the progress of prevention and control efforts in countries. We provide a comprehensive assessment of the levels and trends of HIV/AIDS incidence, prevalence, mortality, and coverage of antiretroviral therapy (ART) for 1980–2017 and forecast these estimates to 2030 for 195 countries and territories.
Methods
We determined a modelling strategy for each country on the basis of the availability and quality of data. For countries and territories with data from population-based seroprevalence surveys or antenatal care clinics, we estimated prevalence and incidence using an open-source version of the Estimation and Projection Package—a natural history model originally developed by the UNAIDS Reference Group on Estimates, Modelling, and Projections. For countries with cause-specific vital registration data, we corrected data for garbage coding (ie, deaths coded to an intermediate, immediate, or poorly defined cause) and HIV misclassification. We developed a process of cohort incidence bias adjustment to use information on survival and deaths recorded in vital registration to back-calculate HIV incidence. For countries without any representative data on HIV, we produced incidence estimates by pulling information from observed bias in the geographical region. We used a re-coded version of the Spectrum model (a cohort component model that uses rates of disease progression and HIV mortality on and off ART) to produce age-sex-specific incidence, prevalence, and mortality, and treatment coverage results for all countries, and forecast these measures to 2030 using Spectrum with inputs that were extended on the basis of past trends in treatment scale-up and new infections.
Findings
Global HIV mortality peaked in 2006 with 1·95 million deaths (95% uncertainty interval 1·87–2·04) and has since decreased to 0·95 million deaths (0·91–1·01) in 2017. New cases of HIV globally peaked in 1999 (3·16 million, 2·79–3·67) and since then have gradually decreased to 1·94 million (1·63–2·29) in 2017. These trends, along with ART scale-up, have globally resulted in increased prevalence, with 36·8 million (34·8–39·2) people living with HIV in 2017. Prevalence of HIV was highest in southern sub-Saharan Africa in 2017, and countries in the region had ART coverage ranging from 65·7% in Lesotho to 85·7% in eSwatini. Our forecasts showed that 54 countries will meet the UNAIDS target of 81% ART coverage by 2020 and 12 countries are on track to meet 90% ART coverage by 2030. Forecasted results estimate that few countries will meet the UNAIDS 2020 and 2030 mortality and incidence targets.
Interpretation
Despite progress in reducing HIV-related mortality over the past decade, slow decreases in incidence, combined with the current context of stagnated funding for related interventions, mean that many countries are not on track to reach the 2020 and 2030 global targets for reduction in incidence and mortality. With a growing population of people living with HIV, it will continue to be a major threat to public health for years to come. The pace of progress needs to be hastened by continuing to expand access to ART and increasing investments in proven HIV prevention initiatives that can be scaled up to have population-level impact
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