Substrate Wettability Influences Internal Jet Formation and Mixing during Droplet Coalescence.

The internal dynamics during the axisymmetric coalescence of an initially static free droplet and a sessile droplet of the same fluid are studied using both laboratory experiments and numerical simulations. A high-speed camera captured internal flows from the side, visualized by adding a dye to the free droplet. The numerical simulations employ the volume of fluid method, with the Kistler dynamic contact angle model to capture substrate wettability, quantitatively validated against the image-processed experiments. It is shown that an internal jet can be formed when capillary waves reflected from the contact line create a small tip with high curvature on top of the coalesced droplet that propels fluid toward the substrate. Jet formation is found to depend on the substrate wettability, which influences capillary wave reflection; the importance of the advancing contact angle subordinated to that of the receding contact angle. It is systematically shown via regime maps that jet formation is enhanced by increasing the receding contact angle and by decreasing the droplet viscosity. Jets are seen at volume ratios very different from those accepted for free droplets, showing that a substrate with appropriate wettability can improve the efficiency of fluid mixing.

Genomics-enabled analysis of the emergent disease cotton bacterial blight.

Cotton bacterial blight (CBB), an important disease of (Gossypium hirsutum) in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm) strains. Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal important insights into the Xcm-G. hirsutum disease complex and strategies for future development of resistant cultivars.

Droplet Misalignment Limit for Inkjet Printing into Cavities on Textured Surfaces.

The control of droplets deposited onto textured surfaces is of great importance for both engineering and medical applications. This research investigates the dynamics of a single droplet deposited into a confined space and its final equilibrium morphology, with emphasis given to droplet deposition under print head misalignment, the effect of nonuniform wettability, and deposition of droplets with varying sizes. A multiphase pseudopotential lattice Boltzmann methodology is used to simulate the process of deposition. The print quality is characterized in terms of a parameter referred to as the wetted fraction, which describes the proportion of the cavity that is wetted by the droplet. Our results show how single and multiple axis misalignment affect the final equilibrium morphology, and it was found for comparable configurations that multiaxis misalignment resulted in a higher wetted fraction. Investigations into wettabilities of the substrate and cavity wall revealed how larger ratios of the contact angles between the two enhance the ability for the droplet to self-align within the cavity. Additionally, a range of uniform wettabilities between the substrate and cavity were found, which mitigate against misalignment. Investigations into varying droplet sizes relative to the cavity revealed how misalignment can be compensated for with larger droplets, and limits for filling a cavity with a single drop are defined. Finally, we explore the deposition with misalignment into closely positioned cavities where it is found that the spacing between cavities is a key factor in determining the maximum permissible misalignment.

Gene expression atlas for the food security crop cassava.

Cassava (Manihot esculenta) feeds c. 800 million people world-wide. Although this crop displays high productivity under drought and poor soil conditions, it is susceptible to disease, postharvest deterioration and the roots contain low nutritional content. Here, we provide molecular identities for 11 cassava tissue/organ types through RNA-sequencing and develop an open access, web-based interface for further interrogation of the data. Through this dataset, we consider the physiology of cassava. Specifically, we focus on identification of the transcriptional signatures that define the massive, underground storage roots used as a food source and the favored target tissue for transgene integration and genome editing, friable embryogenic callus (FEC). Further, we identify promoters able to drive strong expression in multiple tissue/organs. The information gained from this study is of value for both conventional and biotechnological improvement programs.

Constitutively elevated salicylic acid levels alter photosynthesis and oxidative state but not growth in transgenic populus.

Salicylic acid (SA) has long been implicated in plant responses to oxidative stress. SA overproduction in Arabidopsis thaliana leads to dwarfism, making in planta assessment of SA effects difficult in this model system. We report that transgenic Populus tremula × alba expressing a bacterial SA synthase hyperaccumulated SA and SA conjugates without negative growth consequences. In the absence of stress, endogenously elevated SA elicited widespread metabolic and transcriptional changes that resembled those of wild-type plants exposed to oxidative stress-promoting heat treatments. Potential signaling and oxidative stress markers azelaic and gluconic acids as well as antioxidant chlorogenic acids were strongly coregulated with SA, while soluble sugars and other phenylpropanoids were inversely correlated. Photosynthetic responses to heat were attenuated in SA-overproducing plants. Network analysis identified potential drivers of SA-mediated transcriptome rewiring, including receptor-like kinases and WRKY transcription factors. Orthologs of Arabidopsis SA signaling components NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1 and thioredoxins were not represented. However, all members of the expanded Populus nucleoredoxin-1 family exhibited increased expression and increased network connectivity in SA-overproducing Populus, suggesting a previously undescribed role in SA-mediated redox regulation. The SA response in Populus involved a reprogramming of carbon uptake and partitioning during stress that is compatible with constitutive chemical defense and sustained growth, contrasting with the SA response in Arabidopsis, which is transient and compromises growth if sustained.

Asymmetric vitreomacular traction and symmetrical full thickness macular hole formation.

BACKGROUND: A Full Thickness Macular Hole (FTMH) is often associated with vitreomacular traction, and this can be asymmetric with vitreomacular traction on one side of the hole but not the other. In cross-section, the elevated retinal rim around a developed FTMH is seen as a drawbridge elevation, and this drawbridge elevation may be used as a measure of morphological change. Examination of the drawbridge elevation of the retinal rim in FTMH with asymmetric vitreomacular traction may help to clarify the role of vitreomacular traction in the development of FTMH. METHOD: Cases of FTMH were identified with an initial OCT scan showing vitreomacular traction on one side of the hole only and that had a follow-up OCT scan showing progression of the hole. A tangent to the retinal surface at a distance of 700 microns from the axis of the hole was used as a marker of the drawbridge elevation of the retinal rim around the macular hole. Comparisons of the drawbridge elevation and change in drawbridge elevation between the sides with and without initial vitreomacular traction were made. RESULTS: There was no significant difference between the drawbridge elevation, or change in drawbridge elevation, on the side of the hole with initial vitreomacular traction compared to the side without initial traction. CONCLUSION: There is some intrinsic mechanism within the retina to link the morphological changes on the two sides of a FTMH. A bistable hypothesis of FTMH formation and closure is postulated to explain this linkage.

Movement of the inner retina complex during the development of primary full-thickness macular holes: implications for hypotheses of pathogenesis.

BACKGROUND: The inner retinal complex is a well-defined layer in spectral-domain OCT scans of the retina. The central edge of this layer at the fovea provides anatomical landmarks that can be observed in serial OCT scans of developing full-thickness macular holes (FTMH). Measurement of the movement of these points may clarify the mechanism of FTMH formation. METHOD: This is a retrospective study of primary FTMH that had a sequence of two OCT scans showing progression of the hole. Measurements were made of the dimensions of the hole, including measurements using the central edge of the inner retinal complex (CEIRC) as markers. The inner retinal separation (distance between the CEIRC across the centre of the fovea) and the Height-IRS (average height of CEIRC above the retinal pigment epithelium) were measured. RESULTS: Eighteen cases were identified in 17 patients. The average increase in the base diameter (368 microns) and the average increase in minimum linear dimension (187 microns) were much larger than the average increase in the inner retinal separation (73 microns). The average increase in Height-IRS was 103 microns. CONCLUSION: The tangential separation of the outer retina to produce the macular hole is much larger than the tangential separation of the inner retinal layers. A model based on the histology of the Muller cells at the fovea is proposed to explain the findings of this study.

Discontinuous dewetting dynamics of highly viscous droplets on chemically heterogeneous substrates.

HYPOTHESIS: Droplet spreading on heterogeneous (chemical/structural) surfaces has revealed local disturbances that affect the advancing contact line. With droplet dewetting being less studied, we hypothesize that a receding droplet can be perturbed by localized heterogeneity which leads to irregular and discontinuous dewetting of the substrate. EXPERIMENTS: The sessile drop method was used to study droplet dewetting at a wettability boundary. One-half of a hydrophilic surface was hydrophobically modified with either i) methyloctyldichlorosilane or ii) clustered macromolecules. A Lattice Boltzmann method (LBM) simulation was also developed to determine the effect of contact angle hysteresis and boundary conditions on the droplet dynamics. FINDINGS: The two surface treatments were optimized to produce comparable water wetting characteristics. With a negative Gibbs free energy on the hydrophilic-half, the oil droplet receded to the hydrophobic-half. On the silanized surface, the droplet was pinned and the resultant droplet shape was a distorted spherical cap, having receded uniformly on the unmodified surface. Modifying the surface with clustered macromolecules, the droplet receded slightly to form a spherical cap. However, droplet recession was non-uniform and daughter droplets formed near the wettability boundary. The LBM simulation revealed that daughter droplets formed when θR > 164°, with the final droplet shape accurately described by imposing a diffuse wettability boundary condition.

Small Airway Disease in Pediatric Asthma: the Who, What, When, Where, Why, and How to Remediate. A Review and Commentary.

Asthma affects all portions of the airways. Small airways, however, comprise a substantial component of the conducting lung air flow. In asthma, inflammatory processes can affect the whole respiratory tract, from central to peripheral/small airways. The emphasis in adult and pediatric respiratory disease clinics is to focus on large airway obstruction and reversibility. This information, although valuable, underemphasizes a large portion of the conduction airway of asthmatics. Standard descriptions of asthma management focus on a multiple medication approaches. We particularly focused on the management of asthma in the international guidelines for the Global Initiative for Asthma (GINA). Overall, however, minimal attention is placed on the small airway pool in asthma medical management. We took the opportunity to thoroughly review and present specific data from the adult asthma literature which supported the concept that small airway abnormalities may play a role in the pathogenesis and clinical expression of asthma. Based on the conclusions of the adult asthma literature, we here present a thorough review of the literature as it relates to small airway disease in children with asthma. We used, collectively, individual data sources of data to expand the information available from standard diagnostic techniques, especially spirometry, in the evaluation of small airway disease. As the pharmacological approaches to moderate to severe asthma are advancing rapidly into the realm of biologics, we sought to present potential pharmacological options for small airway dysfunction in pediatrics prior to biological modifier intervention.

Polymer-Induced Drag Reduction in Dilute Newtonian and Semi-Dilute Non-Newtonian Fluids: An Assessment of the Double-Gap Concentric Cylinder Method.

Polymer-induced drag reduction (DR) in fluids was studied using a rotational rheometer with double-gap concentric cylinder geometry. Although both polymers (polyacrylamide (PAM) and 2-acrylamido-2-methylpropane sulfonic acid (SPAM)) had molecular weights of several MDa, the contrasting polymer charge, nonionic and anionic, led to different polymer overlap concentrations (c*), PAM ≫ SPAM, and fluid rheology, with PAM fluids mostly Newtonian and SPAM fluids non-Newtonian (shear-thinning). Based on these differences, it was important to account for the infinite shear viscosity and normalize the polymer concentration by the intrinsic concentration (c int) so that the DR performance of the two polymer fluids could be accurately compared. Both polymers induced DR, and the maximum DR by SPAM (DR% = 28) was slightly higher than that by PAM (DR% = 22) when Re p ∼ 1700. For PAM, the loss of DR with time diminished at higher polymer concentrations (≥100 ppm, at Re p = 3149) but was found to be sensitive to high Re p, with polymer chain scission the likely cause of the reduced performance. For the semi-dilute SPAM fluids, the shear stability contrasted that of PAM, showing negligible dependence on the polymer concentration and Re p. The apparent rapid loss of DR was predominantly attributed to a time-dependent effect and not polymer degradation. In pipe flow, the maximum DR for SPAM was higher than that measured by rheometry and was attributed to differences in the flow conditions. However, changes in the normalized DR/c with polymer concentration were found to be consistent between the two flow geometries. Furthermore, the high fluid stresses in pipe flow (at high Re p) led to drag reduction losses consistent with PAM, as the time-dependent effect was not seen.

Low frequency temperature forcing of chemical oscillations.

The low frequency forcing of chemical oscillations by temperature is investigated experimentally in the Belousov-Zhabotinsky (BZ) reaction and in simulations of the Oregonator model with Arrhenius temperature dependence of the rate constants. Forcing with temperature leads to modulation of the chemical frequency. The number of response cycles per forcing cycle is given by the ratio of the natural frequency to the forcing frequency and phase locking is only observed in simulations when this ratio is a whole number and the forcing amplitude is small. The global temperature forcing of flow-distributed oscillations in a tubular reactor is also investigated and synchronisation is observed in the variation of band position with the external signal, reflecting the periodic modulation of chemical oscillations by temperature.

Support for and aspects of use of educational games in family medicine and internal medicine residency programs in the US: a survey.

BACKGROUND: The evidence supporting the effectiveness of educational games in graduate medical education is limited. Anecdotal reports suggest their popularity in that setting. The objective of this study was to explore the support for and the different aspects of use of educational games in family medicine and internal medicine residency programs in the United States. METHODS: We conducted a survey of family medicine and internal medicine residency program directors in the United States. The questionnaire asked the program directors whether they supported the use of educational games, their actual use of games, and the type of games being used and the purpose of that use. RESULTS: Of 434 responding program directors (52% response rate), 92% were in support of the use of games as an educational strategy, and 80% reported already using them in their programs. Jeopardy like games were the most frequently used games (78%). The use of games was equally popular in family medicine and internal medicine residency programs and popularity was inversely associated with more than 75% of residents in the program being International Medical Graduates. The percentage of program directors who reported using educational games as teaching tools, review tools, and evaluation tools were 62%, 47%, and 4% respectively. CONCLUSIONS: Given a widespread use of educational games in the training of medical residents, in spite of limited evidence for efficacy, further evaluation of the best approaches to education games should be explored.

A national program director survey of the shift to competency-based education in ophthalmology.

PURPOSE: To assess the resources, progress, and barriers for program director (PD) compliance with the Accreditation Council for Graduate Medical Education (ACGME) mandate. DESIGN: Survey. PARTICIPANTS: Ophthalmology PDs in the United States. METHODS: A survey instrument was sent to all ophthalmology PDs in the United States. MAIN OUTCOME MEASURES: The survey instrument assessed PD tenure, funding, current efforts, evaluation modalities, barriers, and desired resources to meet the ACGME competency mandate. RESULTS: The survey was completed by 88 of 104 (85%) PDs. Significant disparities exist between PD financial compensation and actual time spent performing PD duties. This disparity and lack of understanding by faculty of the ACGME competencies were the most frequently cited barriers to success in complying with the ACGME mandate. The most commonly utilized assessment tools are the global or 360 degrees evaluations and clinical evaluation exercises. CONCLUSIONS: Program directors surveyed believe they are not receiving adequate resources to allow them to comply with the ACGME mandate. Although some tools have been implemented by PDs for assessing the competencies, additional national and centralized resources would be helpful.

Deceleration of one-dimensional mixing by discontinuous mappings.

We present a computational study of a simple one-dimensional map with dynamics composed of stretching, permutations of equally sized cells, and diffusion. We observe that the combination of the aforementioned dynamics results in eigenmodes with long-time exponential decay rates. The decay rate of the eigenmodes is shown to be dependent on the choice of permutation and changes nonmonotonically with the diffusion coefficient for many of the permutations. The global mixing rate of the map M in the limit of vanishing diffusivity approximates well the decay rates of the eigenmodes for small diffusivity, however this global mixing rate does not bound the rates for all values of the diffusion coefficient. This counterintuitively predicts a deceleration in the asymptotic mixing rate with an increasing diffusivity rate. The implications of the results on finite time mixing are discussed.

Direct reporting of laboratory test results to patients by mail to enhance patient safety.

BACKGROUND: Missed test results are common in clinical practice and compromise patient safety. Direct reporting, whereby testing centers systematically notify both patients and providers of important test results, constitutes a potential solution, but provider acceptance is unknown. OBJECTIVE: To assess provider interest in direct reporting of selected test results and how interest varied across different tests. DESIGN, SETTING, AND PARTICIPANTS: Survey of primary care physicians at a tertiary care academic medical center. MEASUREMENT: Five-point Likert scores were used to gauge each physician's interest (1 = not at all interested to 5 = very interested) in scenarios pertaining to the direct reporting of 3 diagnostic tests of low (DXA scan), intermediate (genital herpes testing), and high (breast biopsy) "emotional impact" and whether interest varied with each test's result (normal vs abnormal). Physicians were also asked to cite specific advantages and disadvantages of direct reporting. RESULTS: The response rate was 73% (148/202). Physician interest in direct reporting decreased progressively as scenarios shifted from low (DXA scan) to high (breast biopsy) emotional impact (P < .001); interest in direct reporting was also higher when results were normal rather than abnormal (P < .001). Common advantages of direct reporting cited by respondents were reductions in workload (selected by 75% of respondents) and reductions in missed diagnoses (38%). The most common concerns were that patients would become unnecessarily frightened (70%) and would seek unreliable information (65%). CONCLUSION: Direct reporting of selected test results to patients is one system for insuring that important results are not missed, but implementation should consider the specific test in question, the test result, and provider preferences.

Beyond journal clubs. Moving toward an integrated evidence-based medicine curriculum.

Incorporating evidence-based medicine (EBM) into clinical practice is an important competency that residency training must address. Residency program directors, and the clinical educators who work with them, should develop curricula to enhance residents' capacity for independent evidence-based practice. In this article, the authors argue that residency programs must move beyond journal club formats to promote the practice of EBM by trainees. The authors highlight the limitations of journal club, and suggest additional curricular approaches for an integrated EBM curriculum. Helping residents become effective evidence users will require a sustained effort on the part of residents, faculty, and their educational institutions.

Nonlocal hydrodynamic influence on the dynamic contact angle: slip models versus experiment.

Experiments reported by Blake [Phys. Fluids., 11, 1995 (1999)] suggest that the dynamic contact angle formed between the free surface of a liquid and a moving solid boundary at a fixed contact-line speed depends on the flow field and geometry near the moving contact line. We examine quantitatively whether or not it is possible to attribute this effect to the bending of the free surface due to hydrodynamic stresses acting upon it and hence interpret the results in terms of the so-called "apparent" contact angle. It is shown that this is not the case. Numerical analysis of the problem demonstrates that, at the spatial resolution reported in the experiments, the variations of the "apparent" contact angle (defined in two different ways) caused by variations in the flow field, at a fixed contact-line speed, are too small to account for the observed effect. The results clearly indicate that the actual (macroscopic) dynamic contact angle--i.e., the one used in fluid mechanics as a boundary condition for the equation determining the free surface shape--must be regarded as dependent not only on the contact-line speed but also on the flow field and geometry in the vicinity of the moving contact line.

Toward Defining the Foundation of the MD Degree: Core Entrustable Professional Activities for Entering Residency.

Currently, no standard defines the clinical skills that medical students must demonstrate upon graduation. The Liaison Committee on Medical Education bases its standards on required subject matter and student experiences rather than on observable educational outcomes. The absence of such established outcomes for MD graduates contributes to the gap between program directors' expectations and new residents' performance.In response, in 2013, the Association of American Medical Colleges convened a panel of experts from undergraduate and graduate medical education to define the professional activities that every resident should be able to do without direct supervision on day one of residency, regardless of specialty. Using a conceptual framework of entrustable professional activities (EPAs), this Drafting Panel reviewed the literature and sought input from the health professions education community. The result of this process was the publication of 13 core EPAs for entering residency in 2014. Each EPA includes a description, a list of key functions, links to critical competencies and milestones, and narrative descriptions of expected behaviors and clinical vignettes for both novice learners and learners ready for entrustment.The medical education community has already begun to develop the curricula, assessment tools, faculty development resources, and pathways to entrustment for each of the 13 EPAs. Adoption of these core EPAs could significantly narrow the gap between program directors' expectations and new residents' performance, enhancing patient safety and increasing residents', educators', and patients' confidence in the care these learners provide in the first months of their residency training.

Forceps delivery volumes in teaching and nonteaching hospitals: are volumes sufficient for physicians to acquire and maintain competence?

PURPOSE: The decline in the use of forceps in operative deliveries over the last two decades raises questions about teaching hospitals' ability to provide trainees with adequate experience in the use of forceps. The authors examined (1) the number of operative deliveries performed in teaching and nonteaching hospitals, and (2) whether teaching hospitals performed a sufficient number of forceps deliveries for physicians to acquire and maintain competence. METHOD: The authors used State Inpatient Data from nine states to identify all women hospitalized for childbirth in 2008. They divided hospitals into three categories: major teaching, minor teaching, and nonteaching. They calculated delivery volumes (total operative, cesarean, vacuum, forceps, two or more methods) for each hospital and compared data across hospital categories. RESULTS: The sample included 1,344,305 childbirths in 835 hospitals. The mean cesarean volumes for major teaching, minor teaching, and nonteaching hospitals were 969.8, 757.8, and 406.9. The mean vacuum volumes were 301.0, 304.2, and 190.4, and the mean forceps volumes were 25.2, 15.3, and 8.9. In 2008, 31 hospitals (3.7% of all hospitals) performed no vacuum extractions, and 320 (38.3%) performed no forceps deliveries. In 2008, 13 (23%) major teaching and 44 (44%) minor teaching hospitals performed five or fewer forceps deliveries. CONCLUSIONS: Low forceps delivery volumes may preclude many trainees from acquiring adequate experience and proficiency. These findings highlighted broader challenges, faced by many specialties, in ensuring that trainees and practicing physicians acquire and maintain competence in infrequently performed, highly technical procedures.