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Host shifts of parasites are often causing devastating effects in the new hosts. The Varroa genus is known for a lineage of Varroa destructor that shifted to the Western honey bee, Apis mellifera, with disastrous effects on wild populations and the beekeeping industry. Despite this, the biology of Varroa spp. remains poorly understood in its native distribution range, where it naturally parasitizes the Eastern honey bee, Apis cerana. Here, we combined mitochondrial and nuclear DNA analyses with the assessment of mite reproduction to determine the population structure and host specificity of V. destructor and Varroa jacobsonii in Thailand, where both hosts and several Varroa species and haplotypes are sympatric. Our data confirm previously described mite haplogroups, and show three novel haplotypes. Multiple infestations of single host colonies by both mite species and introgression of alleles between V. destructor and V. jacobsonii suggest that hybridization occurs between the two species. Our results indicate that host specificity and population genetic structure in the genus Varroa is more labile than previously thought. The ability of the host shifted V. destructor haplotype to spillback to A. cerana and to hybridize with V. jacobsonii could threaten honey bee populations of Asia and beyond.
Understanding the two-way interactions between finite-size solid particles and a wall-bounded turbulent flow is crucial in a variety of natural and engineering applications. Previous experimental measurements and particle-resolved direct numerical simulations revealed some interesting phenomena related to particle distribution and turbulence modulation, but their in-depth analyses are largely missing. In this study, turbulent channel flows laden with neutrally buoyant finite-size spherical particles are simulated using the lattice Boltzmann method. Two particle sizes are considered, with diameters equal to 14.45 and 28.9 wall units. To understand the roles played by the particle rotation, two additional simulations with the same particle sizes but no particle rotation are also presented for comparison. Particles of both sizes are found to form clusters. Under the Stokes lubrication corrections, small particles are found to have a stronger preference to form clusters, and their clusters orientate more in the streamwise direction. As a result, small particles reduce the mean flow velocity less than large particles. Particles are also found to result in a more homogeneous distribution of turbulent kinetic energy (TKE) in the wall-normal direction, as well as a more isotropic distribution of TKE among different spatial directions. To understand these turbulence modulation phenomena, we analyse in detail the total and component-wise volume-averaged budget equations of TKE with the simulation data. This budget analysis reveals several mechanisms through which the particles modulate local and global TKE in the particle-laden turbulent channel flow.
This is a copy of the slides presented at the meeting but not formally written up for the volume.
We have developed unique combinations of in situ and ex situ analytical techniques capable of providing information about thin film growth and interface processes at the atomic scale. The in situ techniques include time-of-flight ion scattering (TOF-ISARS) and mass spectroscopy of recoil ions (MSRI), functional in relatively high background pressure environments such as growth of oxide films in oxygen atmospheres. These techniques are not only powerful for understanding fundamental thin film science, but are also useful for establishing composition-microstructure-property relationships critical for the development of materials integration for fabrication of film-based micro and nanodevices. We will discuss examples of application to understanding ferroelectric and high-k dielectric film growth and interface processes and using this knowledge for developing integration of ferroelectric capacitors with silicon microcircuits for non-volatile ferroelectric random access memories (FERAMs), development of high-K dielectric capacitors for high-frequency devices, and development of new high-K dielectric layers for the next generation of nanoscale CMOS gates. This presentation will include a review of studies of a new TiAl layer developed in our laboratory that can be used as a material with a double diffusion barrier / bottom electrode functionality for integration of ferroelectric capacitors with CMOS devices for fabrication of FeRAMs, high-K dielectric layers with Cu electrodes for high frequency devices, and as a new high-K dielectric for the next generation of nanoscale CMOS devices. We will discuss results from systematic studies designed to understand TiAl film growth and oxidation processes using sputter-deposition in conjunction with complementary in situ characterization techniques mentioned above and ex situ transmission electron microscopy and electrical characterization. This work was supported by the US Department of Energy, BES-Materials Sciences, under Contract W-13-109-ENG-38.
After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.
The objective of the studies reported in this research communication was to investigate the use of whey contaminated with antibiotics such as cephalosporins, quinolones and tetracyclines as a nutrient medium for the growth of Kluyveromyces marxianus with particular attention to the effect of thermal treatment used to overcome the inhibitory effects of antibiotic concentrations close to the Maximum Residue Limits. The heat treatments at 120 °C for 40 min, 120 °C for 83 min, and 120 °C for 91 min caused total inactivation of cephalosporins, tetracyclines and quinolone residues in whey respectively.
Whether seeking refuge from political turmoil or economic calamity, immigrants who are forced to embark on hazardous journeys across the Mediterranean Sea often end up dead. For example, the fourteen-mile stretch of sea separating Tangiers, Morocco, from the southern tip of Spain (a pathway of choice for those seeking better socioeconomic and political situations in Europe) has, since the beginning of this century, become a quotidian deadly route. Migrants’ bodies routinely wash up on Spanish shores or back on the beaches of the Maghreb (Algeria, Morocco, and Tunisia). The horrors of illegal crossings have been repeatedly evoked in written texts and films most noticeably since 2000, as the death toll has increased due to sociopolitical and economic unrest across Africa and the Middle East. In 2016, from Libya alone, more than twenty-one hundred people died trying to cross the sea to escape war. This number, juxtaposed to those officially published by Morocco, Algeria, and Tunisia, paints a picture of hopelessness. The harragas, as they are called in Arabic, are of all colors and religions, from the Maghreb and as far south as Senegal, Mali, and Mauritania. In his work, Ex-Centric Migrations: Europe and the Maghreb in Mediterranean Cinema, Literature, and Music, Hakim Abderrezak explores in depth the connotations of the term harraga. He explains that the noun harragas (plural), the subject of the works of many Maghrebi authors and filmmakers, is a dialectical Arabic deformation of the standard Arabic hrig and harga, which mean burning. Different transcriptions include: lahrig, l'hrig, el hrig, h'rig, harq, and hrague. Abderrezak writes, “Hrig covers the clandestine migrant's 1.) burning desire to leave, 2.) burning of kilometers to the final destination, and 3.) burning identification papers in hopes to make repatriation more difficult for authorities.” As Abderrezak further explains, leaving “one's country clandestinely and the desire to do so are often designated by the terms hrig and harga.” Indeed, a whole vocabulary associated with the harragas has made its way into the contemporary narratives of illegal migration taking place in the Mediterranean basin. Words such as clandestins (French), clandestinos (Spanish) as well as pateras (Spanish) and barques (French), both meaning small fishing boats used to transport the harragas, have all become common terminology used to describe illegal crossings of the Mediterranean Sea.
In this study, we sought to evaluate the influence of cigarette smoke and pH cycling on the chemical composition and surface/cross-sectional enamel microhardness. A total of 40 dental blocks obtained from bovine incisors were divided into four groups (n=10): no treatment (control); exposure to cigarette smoke (CS); exposure to pH cycling (PC); and exposure to cigarette smoke and pH cycling (CS-PC). The samples were analyzed by synchrotron radiation micro X-ray fluorescence, bench mode X-ray fluorescence, as well as surface microhardness (SMH) and cross-sectional microhardness (CSMH) testing. The SMH results were submitted to analysis of variance (ANOVA) and Tukey’s test. The CSMH results were evaluated using split-plot ANOVA and Tukey’s test. A high amount of Cd and Pb and traces of Ni and As were observed in enamel and dentin after exposure to cigarette smoke (CS and CS-PC). The SMH and CSMH of CS were statistically higher when compared with the control. The PC and CS-PC showed lower SMH and CSMH. We conclude that exposure to cigarette smoke promoted heavy metal deposition in enamel/dentin. In addition, it increased the enamel microhardness but did not promote a protective effect on the in vitro development of caries. The clinical significance of this work is that there is significant bioaccumulation of heavy metals from cigarette smoke on the surface and in the enamel and dentin.
Sepsis – syndrome of infection complicated by organ dysfunction – is responsible for over 750 000 hospitalisations and 200 000 deaths in the USA annually. Despite potential nutritional benefits, the association of diet and sepsis is unknown. Therefore, we sought to determine the association between adherence to a Mediterranean-style diet (Med-style diet) and long-term risk of sepsis in the REasons for Geographic Differences in Stroke (REGARDS) cohort. We analysed data from REGARDS, a population-based cohort of 30 239 community-dwelling adults age ≥45 years. We determined dietary patterns from a baseline FFQ. We defined Med-style diet as a high consumption of fruit, vegetables, legumes, fish, cereal and low consumption of meat, dairy products, fat and alcohol categorising participants into Med-style diet tertiles (low: 0–3, moderate: 4–5, high: 6–9). We defined sepsis events as hospital admission for serious infection and at least two systematic inflammatory response syndrome criteria. We used Cox proportional hazard models to determine the association between Med-style diet tertiles and first sepsis events, adjusting for socio-demographics, lifestyle factors, and co-morbidities. We included 21 256 participants with complete dietary data. Dietary patterns were: low Med-style diet 32·0 %, moderate Med-style diet 42·1 % and high Med-style diet 26·0 %. There were 1109 (5·2 %) first sepsis events. High Med-style diet was independently associated with sepsis risk; low Med-style diet referent, moderate Med-style diet adjusted hazard ratio (HR) 0·93 (95 % CI 0·81, 1·08), high Med-style diet adjusted HR=0·74 (95 % CI 0·61, 0·88). High Med-style diet adherence is associated with lower risk of sepsis. Dietary modification may potentially provide an option for reducing sepsis risk.
PA6 and PMMA polymers with different MWCNTs addition (5, 7 and 9 wt %) were synthetized through casting solution, resulting in improvement properties in contrast to pristine polymers. SEM images showed the MWCNTs embedded into polymeric matrices. D, G and G´ bands of MWCNTs were confirmed by Raman spectroscopy and functional groups observed in both nanocomposites by FTIR demonstrated a strong interaction. A significant increasing in electrical conductivity and microhardness was observed in all the nanocomposites. Major microhardness values were obtained in MWCNTs/PA6 (50 HV) however the MWCNTs/PMMA nanocomposites showed the highest electrical conductivity value (6.4×10-4 S/cm).
A novel process for Boron doping of ultrananocrystalline diamond (UNCD) films, using thermal diffusion, is described. Hall measurements show an increase in carrier concentration from 1013 to 1020 cm−3. Ultraviolet Photoelectron Spectroscopy and x-ray Photoelectron Spectroscopy show a band gap of 4.4 eV, a work function of 5.1 eV and a Fermi level at 2.0 eV above the valence band. Boron atoms distribution through UNCD films, was measured by Secondary Ion Mass Spectrometry, revealing Boron atoms diffusivity of about 10−14 cm2/s. Raman spectroscopy and x-ray Diffraction analysis revealed that UNCD films did not suffer graphitization nor structural damage during annealing.
In medical interventional procedures such as brachytherapy, biopsy and radio-frequency ablation, precise tracking through the preplanned desired trajectory is very essential. This important requirement is critical due to two major reasons: anatomical obstacle avoidance and accurate targeting for avoiding undesired radioactive dose exposure or damage to neighboring tissue and critical organs. Therefore, a precise control of the needling device in the unstructured environment in the presence of external disturbance is required to achieve accurate target reaching in clinical applications. In this paper, a shape memory alloy actuated active flexible needle controlled by an adaptive sliding mode controller is presented. The trajectory tracking performance of the needle is tested while having its actual movement in an artificial tissue phantom by giving various input reference trajectories such as multi-step and sinusoidal. Performance of the adaptive sliding mode controller is compared with that of the proportional, integral and derivative controller and is proved to be the effective method in the presence of the external disturbances.
The aim of this research is to ameliorate the dispersion of pristine and functionalized Carbon Nanotubes (CNTs) into polystyrene with hydroxyl end groups (PSOH) matrices using low magnetic fields. The Multi-Walled Carbon Nanotubes (MWCNTs) were synthesized by chemical vapor deposition (CVD) using benzene as carbon source; to produce CNTs with and without functional groups two catalysts were used (stainless steel and ferrocene). The obtained nanotubes contained iron nanoparticles inside. PSOH were synthesized using styrene as monomer, azobisisobutyronitrile as initiator and 2-MeOH as chain transfer agent. The MWCNTs-PSOH matrices were formed using 1.6 wt % of carbon nanotubes into PSOH and ultrasonic mixing for 30 min. The mixing materials were poured into containers and dry at room temperature. While the material was drying, constant magnetic fields of 0.24 T were being applied for 50 min. The MWCNTs-PSOH composites were analysed by SEM, FTIR and Raman spectroscopy. SEM micrographs showed that MWCNTs without functional groups were incorporated in the middle of PSOH. The MWCNTs functionalized perform differently; a better dispersion through the entire polymer matrix was achieved, because the polymer embedded the CNTs. FTIR and Raman spectroscopy showed chemical interaction between PSOH and MWCNTs functionalized. The CNTs dispersion into PSOH was ameliorated through the use of low magnetic fields and functionalization.
Using survey data and interviews, this study examines Panamanian attitudes toward the United States and toward the central issues in US.- Panama relations. It also compares Panamanian attitudes with opinions toward the United States in the rest of Central America. The study finds that nationalism, system support, anticommunism, and, for the mass public, ideology are the most important variables in determining support for the United States. Elites are more nationalistic and less accommodationist toward the United States than the mass public. Concern about the politicization and misuse of the Panama Canal and adjacent lands has led many in the general public to support a continued US. military presence on the Isthmus of Panama.
In this essay I aim to understand how Adam Smith predicted the progress and prosperity of a commercial society and analyze the main attributes of his natural liberty system. I examine the meaning and implications of prosperity in Smith’s thought. Finally, I analyze the role of the division of labor and parsimony in the overall process of societal advancement.
Inspired by recent literature that approaches the dissemination of knowledge from a social interaction perspective, the article explores the dynamics of a prototypical optimal control growth problem structured upon the following features: (i) the model economy is populated by a large number of rational agents; (ii) each agent allocates time, optimally, among production and social interaction; (iii) knowledge spreads through the contact with others; (iv) the propagation of ideas follows two steps—in a first stage, interaction promotes the acquisition of theoretical knowledge and, in a second stage, it works as a catalyst for the successful implementation of the theory to practical productive uses; (v) interaction contributes not only to the diffusion of a given state of technical knowledge—it fosters, as well, the growth of ideas and techniques. The model allows for the endogenous determination of optimal trajectories concerning the allocation of time and the intensity of interaction; moreover, a long-term endogenous growth rate for the economy is derived, with optimal growth being essentially driven by the state of techniques and by the forces that shape the human interaction process.