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Bipartite networks represent pairwise relationships between nodes belonging to two distinct classes. While established methods exist for analyzing unipartite networks, those for bipartite network analysis are somewhat obscure and relatively less developed. Community detection in such instances is frequently approached by first projecting the network onto a unipartite network, a method where edges between node classes are encoded as edges within one class. Here we test seven different projection schemes by assessing the performance of community detection on both: (i) a real-world dataset from social media and (ii) an ensemble of artificial networks with prescribed community structure. A number of performance and accuracy issues become apparent from the experimental findings, especially in the case of long-tailed degree distributions. Of the methods tested, the “hyperbolic” projection scheme alleviates most of these difficulties and is thus the most robust scheme of those tested. We conclude that any interpretation of community detection algorithm performance on projected networks must be done with care as certain network configurations require strong community preference for the bipartite structure to be reflected in the unipartite communities. Our results have implications for the analysis of detected community structure in projected unipartite networks.
Failing to communicate a message in everyday settings can be a frustrating experience. However, miscommunication can lead to disaster in high-stakes situations. Yet in these contexts, under pressure to perform efficiently, speakers may also find themselves with limited resources to devote to message clarity. To understand how cognitive constraint affects communication and explore a possible low-cost solution, we investigated a method for moderating ambiguity production in the face of competing attentional demands: taking the perspective of the listener. Over two experiments, speakers labeled images (Experiment 1) or provided instructions (Experiment 2) to listeners in a non-interactive communication task. In both experiments, speakers were randomly assigned to cognitive constraint and perspective-taking conditions, such that some speakers were under higher cognitive constraint and some speakers received a simple perspective-taking directive. We replicated previous findings that additional cognitive constraint impairs speakers’ ability to avoid ambiguity. Additionally, we found that a simple directive can promote speaker clarity when labeling images, but not when providing instructions. These results suggest that a simple directive is likely insufficient to ensure speaker clarity in all cases.
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.
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.
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.
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.
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.
To describe the epidemiology of hospital-acquired infections (HAIs) in veterans with spinal cord injury and disorder (SCI&D).
Retrospective medical record review.
Midwestern Department of Veterans Affairs spinal cord injury center.
A total of 226 patients with SCI&D hospitalized at least once during a 2-year period (October 1, 2001, through September 30, 2003).
A total of 549 hospitalizations were included in the analysis (mean duration of hospitalization, 33.7 days); an HAI occurred during 182 (33.2%) of these hospitalizations. A total of 657 HAIs occurred during 18,517 patient-days in the hospital (incidence rate, 35.5 HAIs per 1,000 patient-days). Almost half of the 226 patients had at least 1 HAI; the mean number of HAIs among these patients was 6.0 HAIs per patient. The most common HAIs were urinary tract infection (164 [25.0%] of the 657 HAIs; incidence rate, 8.9 cases per 1,000 patient-days), bloodstream infection (111 [16.9%]; incidence rate, 6.0 cases per 1,000 patient-days), and bone and joint infection (103 [15.7%]; incidence rate, 5.6 cases per 1,000 patient-days). The most common culture isolates were gram-positive bacteria (1,082 [45.6%] of 2,307 isolates), including Staphylococcus aureus, and gram-negative bacteria (1,033 [43.6%] of isolates), including Pseudomonas aeruginosa. Multivariate regression demonstrated that predictors of HAI were longer length of hospital stay (P = .002), community-acquired infection (P = .007), and use of a urinary invasive device (P = .01) or respiratory invasive device (P = .04).
The overall incidence of HAIs in persons with SCI&D was higher than that reported for other populations, confirming the increased risk of HAI in persons with spinal cord injury. The increased risk associated with longer length of stay and with community-acquired infection suggests that strategies are needed to reduce the duration of hospitalization and to effectively treat community-acquired infection, to decrease infection rates. There is significant room for improvement in reducing the incidence of HAIs in this population.
We present a new gas-grain chemical model that allows the grain-surface formation of saturated, complex, organic species from their constituent functional-groups–basic building blocks that derive from the cosmic ray-induced photodissociation of the granular ice mantles. The surface mobility of the funtional-group radicals is crucial to the reactions, and much of the formation of complex molecules occurs at the intermediate temperatures (~20–40 K) attained during the warm-up of the hot core. Our model traces the evolution of a large range of detected, and as yet un-detected, complex molecules.
Butyrate is an important substrate for maintenance of colonic health and oligofructose fermentation by human faecal bacteria can increase butyrate production in vitro. However, oligofructose appears to be fermented by mainly acetate and lactate-producing bacteria rather than butyrate-producing bacteria. Isotope labelling studies using [U-13C6]glucose were used to show that 13C2 and 13C4 were the major labelled butyrate species produced from glucose fermentation, via [13C2]acetate–acetyl CoA as intermediate. Bacterial interconversion reactions were quantified and acetate conversion to butyrate and lactate conversion to acetate, propionate and butyrate were observed. Addition of oligofructose to faecal batch cultures significantly increased butyrate production. Of the newly synthesised butyrate from oligofructose fermentation, 80% was derived from interconversion of extracellular acetate and lactate, with acetate being quantitatively more significant. Carbohydrates, such as oligofructose, have prebiotic properties. In addition, oligofructose selectively stimulates the bacterial conversion of acetate and lactate to butyrate. Carbohydrates with similar properties represent a refinement of the prebiotic definition, termed butyrogenic prebiotics, because of their additional functionality.
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.
Improved management of mental illness and substance misuse comorbidity is a National Health Service priority, but little is known about its prevalence and current management.
To measure the prevalence of comorbidity among patients of community mental health teams (CMHTs) and substance misuse services, and to assess the potential for joint management.
Cross-sectional prevalence survey in four urban UK centres.
Of CMHT patients, 44% (95% CI 38.1-49.9) reported past-year problem drug use and/or harmful alcohol use; 75% (95% CI 68.2-80.2) of drug service and 85% of alcohol service patients (95% CI 74.2-931) had a past-year psychiatric disorder. Most comorbidity patients appear ineligible for cross-referral between services. Large proportions are not identified by services and receive no specialist intervention.
Comorbidity is highly prevalent in CMHT, drug and alcohol treatment populations, but may be difficult to manage by cross-referral psychiatric and substance misuse services as currently configured and resourced.