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Better control of highly pathogenic avian influenza (HPAI) outbreaks requires deeper understanding of within-flock virus transmission dynamics. For such fatal diseases, daily mortality provides a proxy for disease incidence. We used the daily mortality data collected during the 2015 H5N2 HPAI outbreak in Minnesota turkey flocks to estimate the within-flock transmission rate parameter (β). The number of birds in Susceptible, Exposed, Infectious and Recovered compartments was inferred from the data and used in a generalised linear mixed model (GLMM) to estimate the parameters. Novel here was the correction of these data for normal mortality before use in the fitting process. We also used mortality threshold to determine HPAI-like mortality to improve the accuracy of estimates from the back-calculation approach. The estimated β was 3.2 (95% confidence interval (CI) 2.3–4.3) per day with a basic reproduction number of 12.8 (95% CI 9.2–17.2). Although flock-level estimates varied, the overall estimate was comparable to those from other studies. Sensitivity analyses demonstrated that the estimated β was highly sensitive to the bird-level latent period, emphasizing the need for its precise estimation. In all, for fatal poultry diseases, the back-calculation approach provides a computationally efficient means to obtain reasonable transmission parameter estimates from mortality data.
This study examined the effectiveness of a formal postdoctoral education program designed to teach skills in clinical and translational science, using scholar publication rates as a measure of research productivity.
Participants included 70 clinical fellows who were admitted to a master’s or certificate training program in clinical and translational science from 1999 to 2015 and 70 matched control peers. The primary outcomes were the number of publications 5 years post-fellowship matriculation and time to publishing 15 peer-reviewed manuscripts post-matriculation.
Clinical and translational science program graduates published significantly more peer-reviewed manuscripts at 5 years post-matriculation (median 8 vs 5, p=0.041) and had a faster time to publication of 15 peer-reviewed manuscripts (matched hazard ratio = 2.91, p=0.002). Additionally, program graduates’ publications yielded a significantly higher average H-index (11 vs. 7, p=0.013).
These findings support the effectiveness of formal training programs in clinical and translational science by increasing academic productivity.
To determine the impact of recurrent Clostridium difficile infection (RCDI) on patient behaviors following illness.
Using a computer algorithm, we searched the electronic medical records of 7 Chicago-area hospitals to identify patients with RCDI (2 episodes of CDI within 15 to 56 days of each other). RCDI was validated by medical record review. Patients were asked to complete a telephone survey. The survey included questions regarding general health, social isolation, symptom severity, emotional distress, and prevention behaviors.
In total, 119 patients completed the survey (32%). On average, respondents were 57.4 years old (standard deviation, 16.8); 57% were white, and ~50% reported hospitalization for CDI. At the time of their most recent illness, patients rated their diarrhea as high severity (58.5%) and their exhaustion as extreme (30.7%). Respondents indicated that they were very worried about getting sick again (41.5%) and about infecting others (31%). Almost 50% said that they have washed their hands more frequently (47%) and have increased their use of soap and water (45%) since their illness. Some of these patients (22%–32%) reported eating out less, avoiding certain medications and public areas, and increasing probiotic use. Most behavioral changes were unrelated to disease severity.
Having had RCDI appears to increase prevention-related behaviors in some patients. While some behaviors are appropriate (eg, handwashing), others are not supported by evidence of decreased risk and may negatively impact patient quality of life. Providers should discuss appropriate prevention behaviors with their patients and should clarify that other behaviors (eg, eating out less) will not affect their risk of future illness.
We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing pr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 Mʘ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and lb supernovae.
Photo-actuating structures inspired by the chemical sensing and signal transmission observed in sun-tracking leaves have recently been proposed by Dicker et al. The proposed light tracking structures are complex, multicomponent material systems, principally composed of a reversible photoacid or base, combined with a pH responsive hydrogel actuator. New modelling and characterization approaches for pH responsive hydrogels are presented in order to facilitate the development of the proposed structures. The model employs Donnan equilibrium for the prediction of hydrogel swelling in systems where the pH change is a variable resulting from the equilibrium interaction of all free and fixed (hydrogel) species. The model allows for the fast analysis of a variety of combinations of material parameters, allowing for the design space for the proposed photo-actuating structures to be quickly established. In addition, experimental examination of the swelling of a polyether-based polyurethane and poly(acrylic acid) interpenetrating network hydrogel is presented. The experiment involves simultaneously performing a titration of the hydrogel, and undertaking digital image correlation (DIC) to determine the hydrogel’s state of swelling. DIC allows for the recording of the hydrogel’s state of swelling with previously unattained levels of resolution. Experimental results provide both model material properties, and a means for model validation.
ZnO nanorods grown on plastic substrates by chemical methods are combined with both inorganic and organic p-type materials to make flexible p-n junction devices. When bent the devices generate both voltage and current peaks, which is attributed to the piezoelectric effect in the ZnO nanorods. The best device produces a maximum possible power density of 100 nWcm‑2. When vibrated at a constant frequency the voltage output by the devices scales linearly with vibration amplitude. Also, when illuminated the output of the devices drops. These effects are consistent with a piezoelectric source of the voltage.
In Vietnam, highly pathogenic avian influenza (HPAI) H5N1 infections in poultry often occur without concomitant clinical signs and outbreaks are not consistently reported. Live bird markets represent a convenient site for surveillance that does not rely on farmers' notifications. Two H5N1 surveys were conducted at live bird markets/slaughter points in 39 districts (five provinces) in the Red River, Mekong delta, and central Vietnam during January and May 2011. Oropharyngeal and rectal swab samples from 12 480 ducks were tested for H5N1 by reverse transcription–polymerase chain reaction in pools of five. Traders and stallholders were interviewed using standardized questionnaires; 3·3% of pools tested positive. The highest prevalence (6·6%) corresponded to the Mekong delta, and no H5N1 was detected in the two Red River provinces. The surveys identified key risk behaviours of traders and stallholders. It is recommended that market surveys are implemented over time as a tool to evaluate progress in HPAI control in Vietnam.
Alternaria cassiae and Colletotrichum truncatum are bioherbicidal pathogens of sicklepod, and hemp sesbania, respectively. The effects of simulated rainfall followed by 12 h simulated dew application, immediately or delayed by 1 to 4 h, on disease severity and weed control were studied for each pathogen on its weed host under greenhouse conditions. After each simulated rainfall event, treated plants were placed in a dew chamber for 12 h. Regardless of rainfall amount and/or timing, only slight differences occurred on A. cassiae disease severity and sicklepod control (85 to 100% for both parameters). However, when similar tests were imposed on C. truncatum, disease severity and hemp sesbania control were highly variable, ranging from 5 to 100%. Regardless of rainfall amount, disease development and control of hemp sesbania were greatly reduced (60%) when dew application was delayed by only 1 h following inoculation, regardless of rainfall treatment. Rainfall at 1.27 and 2.58 cm had little effect on disease development and control in hemp sesbania, but the effect of transfer time to dew application exhibited a greater role on these parameters. Thus the time between bioherbicide application and dew application was more important for C. truncatum than for A. cassiae. These results indicate that rainfall amounts and the timing of dew application caused differential effects on disease severity and weed control after application of these bioherbicides to their target weeds.
Recent models of hot cores have incorporated previously-uninvestigated chemical pathways that lead to the formation of complex organic molecules (COMs; i.e. species containing six or more atoms). In addition to the gas-phase ion-molecule reactions long thought to dominate the organic chemistry in these regions, these models now include photodissociation-driven grain surface reaction pathways that can also lead to COMs. Here, simple grain surface ice species photodissociate to form small radicals such as OH, CH3, CH2OH, CH3O, HCO, and NH2. These species become mobile at temperatures above 30 K during the warm-up phase of star formation. Radical-radical addition reactions on grain surfaces can then form an array of COMs that are ejected into the gas phase at higher temperatures. Photodissociation experiments on pure and mixed ices also show that these complex molecules can indeed form from simple species. The molecules predicted to form from this type of chemistry reasonably match the organic inventory observed in high mass hot cores such as Sgr B2(N) and Orion-KL. However, the relative abundances of the observed molecules differ from the predicted values, and also differ between sources. Given this disparity, it remains unclear whether grain surface chemistry governed by photodissociation is the dominant mechanism for the formation of COMs, or whether other unexplored gas-phase reaction pathways could also contribute significantly to their formation. The influence that the physical conditions of the source have on the chemical inventory also remains unclear. Here we overview the chemical pathways for COM formation in hot cores. We also present new modeling results that begin to narrow down the possible routes for production of COMs based on the observed relative abundances of methyl formate (HCOOCH3) and its C2H4O2 structural isomers.
Optical absorption measurements were used to investigate deep defects in proton irradiated doped and undoped AlGaN thin films grown on sapphire substrates. Several samples were proton irradiated with energies ranging between 10 keV and 1 MeV. In certain samples, multiple-energy ion implantation was found necessary to produce a defect, which is responsible for the absorption band observed at 4.61 eV with a shoulder at around 4.10 eV in Al0.6Ga0.4N. Furnace thermal annealing of the irradiated samples show that this absorption band starts to anneal out at temperature as low as 200 oC. A combined isochronal and isothermal annealing in the temperature range of 200- 350°C shows that the activation energy (enthalpy associated with the migration process) of this defect is approximately 0.41 eV. This leads us to conclude that this absorption band is due to a N-vacancy related defect. It is observed that the peak position energy of the absorption band due to this defect is shifted depending on the Al mole fraction in good agreement with the theoretical predictions.
Measurements are presented which show the effect of proton irradiation on the irreversibility line and critical current in Tl2 CaBa2Cu2O8 thin films. These data show that the irreversibility line is dependent on the defect structure and that the pinning energy is increased by proton irradiation. This leads to an increase in the critical current density at 60 K for the lowest radiation dose. Further irradiation reduces the critical current, even while the irreversibility line is enhanced.
This paper discusses the formation of metal clusters on Xe buffer layers and the deposition of those clusters on GaAs, silica, and Bi2Sr2CaCu2O8 when the Xe is desorbed. These clusters contain hundreds to thousands of atoms, and their interactions with the substrate is different from that encountered when atoms are deposited directly. Since cluster assembly alters the reaction pathway at the surface, novel structures with unique chemical and physical properties can be stabilized.
To better understand the effects of magnetic nanoparticles to nuclear spectra and spin relaxation in different systems, we have studied 1H NMR spectra and spin dynamics of the host system in liquid and solid suspensions of γ-Fe2O3 nanoparticles. Significant line broadening of 1H NMR spectra and growing relaxation rates were observed with increased concentration of nanoparticles in the liquid systems, with the relation T1/T2 depending on the particular host. Solid systems demonstrate inhomogeneous broadening of the spectra and practically no dependence of T1 upon the nanoparticle concentration. We explain the experimental results taking into account predomination of diffusion as a source of the relaxation, and estimate effective parameters of relaxation in the systems in study.
Defect location and identification in the metallization systems of ultra-large-scale integrated (ULSI) devices is becoming increasingly important because of the demands of high device density. An understanding of the sources of defects is crucial to the fabrication of submicron devices. Typically, defect identification is accomplished by electrically testing large metal combs and serpents followed by scanning electron microscopy (SEM) investigation. In order to identify metallization defects quickly, we have fabricated a novel device that bypasses the need to electrically probe. This technique utilizes voltage contrast imaging in-situ SEM to locate defects typically found during ULSI device fabrication. While voltage contrast imaging has been used to locate defects in conjuction with externally applied voltages , our technique takes advantage of the SEM's own beam as a charging source and makes close resolution (<0.1μm) inspection unnecessary until appropriate. In this way, defects can be located and identified using ∼/20th the time presently required.
In studying the effective medium theories, polarization is hardly given a consideration in deciding the effective properties of a composite where the host and inclusion phases follow different constitutive equations. A significant conclusion of this paper is that eventhough the composite has discrete inclusions, with the inclusion phase obeying different constitutive properties than the host, the effective medium shows a preference for the inclusion behavior rather than the host which is continuous. As an example, results on polarization study are detailed for the specific case of chiral composites. Application of similar principles is presently explored in more complex problems like the elastic wave propagation through piezoelectric composites and the acoustic wave propagation through sediments.
Photoemission study of the Ga/InP(110) interface, in particular at the In 4d cooper minimum (CM) reveals that the growth of the deposited Ga on InP(110) at room temperature (RT) has two modes: chemisorption at low coverage and metallic island formation at high coverage, whereas the Ga overlayer is much more uniform at 80K low temperature (LT). A replacement reaction between Ga and InP is found to take place only underneath the Ga islands. Metal screening from the Ga islands is suggested to weaken the substrate bonds and enhance the replacement reaction. Distinct behavior of Fermi level pinning has been observed at different temperatures. This is correlated with the temperature dependence of the overlayer morphology as well as the interfacial reaction.
Epitaxy of CoSi2 layers on Si crystal surfaces can be strongly influenced by growing appropriate template layers. The electronic structure of thin (∼7Å) epitaxial CoSi2 films on Si(100) has been studied with angle-resolved photoemission to investigate atomic bonding in the layers and at their boundaries. Most Co atoms in the layers are in a CoSi2-like environment, including those Co atoms near the free surface. Cobalt atoms at the Si-CoSi 2 interface seem to have fewer Si neighbors.
The deposition of in situ phosphorus doped silicon films was performed using disilane (Si2H6) instead of monosilane (SiH4) as the silicon source gas. The negative aspects of in situ doping with phosphine, namely low deposition rates and poor across wafer uniformity, were to a large extent eliminated. Haze-free polycrystalline films were deposited at ∼60 Å-min1 with less than 5% radial thickness variation over a 100 mm wafer. However, the temperature suitable for depositing films using Si2H6 was shifted downward from that used for SiH4 and similarly, the conditions for good quality (haze-free)films were adjusted. Within specific temperature ranges, varying the gas pressure, flow,and Si2H6 to PH3 ratio resulted in the formation of oneof three types of haze. The films produced had unusually low resistivities of ∼770 μohm-cm after furnace annealing at 850ºC for 1800s. A 20 nm thick surface layer of amorphous silicon oxide was revealed during transmission electron microscopy (TEM) examination of annealed films. Although this oxide layer was undoped, the phosphorus gradient, measured by energy dispersive x-ray analysis (EDX) and secondary ion mass spectroscopy (SIMS), increased towards the surface of the polycrystalline film, suggesting that dopant was diffusing to the surface. A matrix involving different annealing and capping layers was conducted to investigate this phenomenon further. Extremely large grains resulted when a capping layer of SiO2 was deposited prior to rapid thermalannealing (RTA). An autodoping effect was observed when another capping layer, such as undoped polycrystalline silicon, was used.