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Soft matter has historically been an unlikely candidate for investigation by electron microscopy techniques due to damage by the electron beam as well as inherent instability under a high vacuum environment. Characterization of soft matter has often relied on ensemble-scattering techniques. The recent development of cryogenic transmission electron microscopy (cryo-TEM) provides the soft matter community with an exciting opportunity to probe the structure of soft materials in real space. Cryo-TEM reduces beam damage and allows for characterization in a native, frozen-hydrated state, providing direct visual representation of soft structure. This article reviews cryo-TEM in soft materials characterization and illustrates how it has provided unique insights not possible by traditional ensemble techniques. Soft matter systems that have benefited from the use of cryo-TEM include biological-based “soft” nanoparticles (e.g., viruses and conjugates), synthetic polymers, supramolecular materials as well as the organic–inorganic interface of colloidal nanoparticles. Many challenges remain, such as combining structural and chemical analyses; however, the opportunity for soft matter research to leverage newly developed cryo-TEM techniques continues to excite.
Why do hosts vary so much in parasite burden, how does this variation translate to variation in host demographic rates and parasite transmission, and how does varied transmission intensity impact selection upon immune defence of individuals? The theoretical foundations of disease ecology provide predictions for the answers to these questions, yet testing such predictions with empirical data poses many challenges. We show how the long-term ecological and genetic study of the unmanaged Soay sheep of St Kilda has addressed fundamental questions in disease ecology, with longitudinal data on parasite burden, immune defence, condition, survival, and fecundity of >10,000 individuals. The rich individual-scale data are complemented by >30 years of data on sheep population dynamics and genetic diversity as well as parasite dynamics and diversity. Population-scale work has documented the range of parasite species present and the contribution of the most prevalent and virulent parasites to regulating sheep dynamics. Individual-scale work has identified drivers of variation in parasite burden and tested hypotheses about costs and benefits of defence in a quest to determine how natural selection has shaped immune function of the sheep.
This article focuses on the finite element modeling of toroidal microinductors, employing first-of-its-kind nanocomposite magnetic core material and superparamagnetic iron nanoparticles covalently cross-linked in an epoxy network. Energy loss mechanisms in existing inductor core materials are covered as well as discussions on how this novel core material eliminates them providing a path toward realizing these low form factor devices. Designs for both a 2 μH output and a 500 nH input microinductor are created via the model for a high-performance buck converter. Both modeled inductors have 50 wire turns, less than 1 cm3 form factors, less than 1 Ω AC resistance, and quality factors, Q’s, of 27 at 1 MHz. In addition, the output microinductor is calculated to have an average output power of 7 W and a power density of 3.9 kW/in3 by modeling with the 1st generation iron nanocomposite core material.
Significant reductions recently seen in the size of wide-bandgap power electronics have not been accompanied by a relative decrease in the size of the corresponding magnetic components. To achieve this, a new generation of materials with high magnetic saturation and permeability are needed. Here, we develop gram-scale syntheses of superparamagnetic Fe/FexOy core–shell nanoparticles and incorporate them as the magnetic component in a strongly magnetic nanocomposite. Nanocomposites are typically formed by the organization of nanoparticles within a polymeric matrix. However, this approach can lead to high organic fractions and phase separation; reducing the performance of the resulting material. Here, we form aminated nanoparticles that are then cross-linked using epoxy chemistry. The result is a magnetic nanoparticle component that is covalently linked and well separated. By using this ‘matrix-free’ approach, we can substantially increase the magnetic nanoparticle fraction, while still maintaining good separation, leading to a superparamagnetic nanocomposite with strong magnetic properties.
Introduction: NSAIDS offer more effective analgesia than opioids, require less rescue medication, and decrease the incidence of nausea and vomiting in renal colic patients. Alpha blockers and Opioids are also prescribed frequently, but doses used and treatment durations are not well described. Our objective was to investigate ED prescribing decisions and medication compliance by patients with acute renal colic. Methods: In this prospective two-city cohort study, we invited patients with a first ED visit for image-confirmed 2-10 mm ureteric stones to consent to a telephone survey 10 days after their ED visit. During follow-up interviews, patients were asked what drugs they were prescribed and how many doses they required. This study was REB approved. Results: A convenience sample of 224 patients, including 152 males (67.9%) and 72 females (median age= 52.4 years) completed 10-day surveys. NSAIDS were prescribed for 48.7%, tamsulosin for 65.2% and opioids for 81.7%. One-third received a tamsulosin-NSAID combination, 40% an opioid-NSAID combination and 28% a tamsulosin-NSAID-opioid combination. Of 109 patients prescribed an NSAID, only 70 (64.2%) took 1 dose/day; however an additional 28 who were not prescribed NSAIDs took 1 NSAID dose/day. Mean (sd) NSAID intake in the overall study group was 1.1 (1.5) doses/day from day 1-5 and 0.6 (1.1) doses/day on days 6-10, with 90%ile values of 3.0 and 2.0 doses/day. NSAID compliance was more common in patients who stated they received high quality discharge instructions (63.8% vs. 32.6%; RR=1.95; 95% CI 1.47-2.60). Mean opioid intake in the overall study group was 1.2 (1.7) doses/day from day 1-5 and 0.5 (1.3) doses/day on days 6-10, with 90%ile values of 4.0 and 2.0 doses/day. Among patients prescribed tamsulosin, the average was 4.0 days of compliance (sd=4.3), with a 90%ile value of 10 days. Conclusion: This study provides estimates for the amount of drug actually used by renal colic patients during the 10-days after their ED visit. Patients used fewer opioid doses than expected, and NSAID and tamsulosin compliance appears relatively poor. NSAID compliance was better in patients who perceived high quality discharge instructions. This study suggests there is room for improvement in medication prescribing and discharge instructions for ED patients with an acute episode of ureteral colic.
The management of human immunodeficiency virus (HIV) infection continues to evolve rapidly. Amazing advances have been made in therapy of primary infection, prevention of opportunistic infections, and prevention of perinatal transmission since the first cases of acquired immune deficiency syndrome (AIDS) were described in 1981. Perinatal transmission rates have decreased from 20–30% early in the epidemic to < 1% in high-income countries with the use of antiretroviral therapy and scheduled cesarean delivery.
Matter in neutron star cores reaches extremely high densities, forming states of matter that cannot be generated in the laboratory. The Equation of State (EOS) of the matter links to macroscopic observables, such as mass M and radius R, via the stellar structure equations. A promising technique for measuring M and R exploits hotspots (burst oscillations) that form on the stellar surface when material accreted from a companion star undergoes a thermonuclear explosion. As the star rotates, the hotspot gives rise to a pulsation, and relativistic effects encode information about M and R into the pulse profile. However the burst oscillation mechanism remains unknown, introducing uncertainty when inferring the EOS. I review the progress that we are making towards cracking this long-standing problem, and establishing burst oscillations as a robust tool for measuring M and R. This is a major goal for future large area X-ray telescopes.
In this study the onset of stress-free Boussinesq thermal convection in rotating spherical shells with aspect ratio η = rinner/router = 0.9, Prandtl numbers Pr ∈ [10−4, 10−1], and Taylor numbers Ta ∈ [104, 1012] is considered. We focus on the form of the convective cell pattern that develops, and on its time scales, since this may have observational consequences for thermonuclear burning and the development of burst oscillations in the exploding oceans of accreting neutron stars (Watts (2012)).
Superburst oscillations are high frequency X-ray variations observed during hours’ long superbursts on accreting neutron stars. We investigate a potential mechanism to explain these observations; a buoyant r-mode, excited in the ocean layers of the star. These modes are affected by ash composition in the ocean so are a good probe of nuclear burning processes. The phenomenon could be used in pulse profile modelling as a way of measuring neutron star mass and radius, and so the dense matter equation of state.
The University of Tasmania balloon-borne large area X-ray telescope was flown from Alice Springs on 20 November 1978. A number of known X-ray sources were observed and a transient increase believed to be a gamma ray burst was detected.
We assessed evidence of exposure to viruses and bacteria in an unmanaged and long-isolated population of Soay sheep (Ovis aries) inhabiting Hirta, in the St Kilda archipelago, 65 km west of Benbecula in the Outer Hebrides of Scotland. The sheep harbour many metazoan and protozoan parasites but their exposure to viral and bacterial pathogens is unknown. We tested for herpes viral DNA in leucocytes and found that 21 of 42 tested sheep were infected with ovine herpesvirus 2 (OHV-2). We also tested 750 plasma samples collected between 1997 and 2010 for evidence of exposure to seven other viral and bacterial agents common in domestic Scottish sheep. We found evidence of exposure to Leptospira spp., with overall seroprevalence of 6·5%. However, serological evidence indicated that the population had not been exposed to border disease, parainfluenza, maedi-visna, or orf viruses, nor to Chlamydia abortus. Some sheep tested positive for antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) but, in the absence of retrospective faecal samples, the presence of this infection could not be confirmed. The roles of importation, the pathogen–host interaction, nematode co-infection and local transmission warrant future investigation, to elucidate the transmission ecology and fitness effects of the few viral and bacterial pathogens on Hirta.
This study aimed to estimate the prevalence and risk factors for hepatitis C virus (HCV) infection in Mexican Americans living in South Texas. We tested plasma for the presence of HCV antibody from the Cameron County Hispanic Cohort (CCHC), a randomized, population-based cohort in an economically disadvantaged Mexican American community on the United States/Mexico border with high rates of chronic disease. A weighted prevalence of HCV antibody of 2·3% [n = 1131, 95% confidence interval (CI) 1·2–3·4] was found. Participants with diabetes had low rates of HCV antibody (0·4%, 95% CI 0·0–0·9) and logistic regression revealed a statistically significant negative association between HCV and diabetes (OR 0·20, 95% CI 0·05–0·77) after adjusting for sociodemographic and clinical factors. This conflicts with reported positive associations of diabetes and HCV infection. No classic risk factors were identified, but important differences between genders emerged in analysis. This population-based study of HCV in Mexican Americans suggests that national studies do not adequately describe the epidemiology of HCV in this border community and that unique risk factors may be involved.
Using several methods to distinguish dart and arrow points, archaeologists have suggested that the bow and arrow appeared in various parts of the world between ˜65,000 and 1,000 years ago. Hildebrandt and King (2012) proposed a dart-arrow index (DAI) to help differentiate dart and arrow points, rejecting claims that the bow and arrow was introduced to western North America prior to the Late Holocene. We used the DAI and other methods to evaluate ˜11,700-year-old projectile points from Santa Rosa Island, obtaining mean values below the threshold for darts, comparable to several North American arrow point types. We have no direct evidence that these small points were used on darts, arrows, or hand-thrown spears, but faunal associations suggest that they may have served as harpoon tips used on atlatl darts to capture birds, fish, and marine mammals. The DAI and other methods for discriminating between dart and arrow points are based almost exclusively on ethnographic and archaeological specimens from interior regions. Our analysis suggests that such methods should not be applied universally, especially in coastal or other aquatic settings, and that archaeologists should continue to critically assess the antiquity of the bow and arrow and the function of projectile points worldwide.
Tall buttercup, a native of central and northern Europe, has become
naturalized in the United States and Canada, and in South Africa, Tasmania
and New Zealand. In Canada and New Zealand it has become an economically
significant weed in cattle-grazed pastures. In this study we develop a
CLIMEX model for tall buttercup and use it to project the weed's potential
distribution under current and future climates and in the presence and
absence of irrigation. There was close concordance between the model's
projection of suitable climate and recorded observations of the species. The
projection was highly sensitive to irrigation; the area of potentially
suitable land globally increasing by 30% (from 34 to 45 million
km2) under current climate when a “top-up” irrigation regime
(rainfall topped up 4 mm d−1 on irrigable land), was included in
the model. Most of the area that becomes suitable under irrigation is
located in central Asia and central North America. By contrast, climate
change is projected to have the opposite effect; the potential global
distribution diminishing by 18% (from 34 to 28 million km2). This
range contraction was the net result of a northward expansion in the
northern limit for the species in Canada and the Russian Federation, and a
relatively larger increase in the land area becoming unsuitable mainly in
central Asia and south eastern United States.