Shear thickening in densely packed suspensions of spheres and rods confined to few layers

We investigate confined shear thickening suspensions for which the sample thickness is comparable to the particle dimensions. Rheometry measurements are presented for densely packed suspensions of spheres and rods with aspect ratios 6 and 9. By varying the suspension thickness in the direction of the shear gradient at constant shear rate, we find pronounced oscillations in the stress. These oscillations become stronger as the gap size is decreased, and the stress is minimized when the sample thickness becomes commensurate with an integer number of particle layers. Despite this confinement-induced effect, viscosity curves show shear thickening that retains bulk behavior down to samples as thin as two particle diameters for spheres, below which the suspension is jammed. Rods exhibit similar behavior commensurate with the particle width, but they show additional effects when the thickness is reduced below about a particle length as they are forced to align; the stress increases for decreasing gap size at fixed shear rate while the shear thickening regime gradually transitions to a Newtonian scaling regime. This weakening of shear thickening as an ordered configuration is approached contrasts with the strengthening of shear thickening when the packing fraction is increased in the disordered bulk limit, despite the fact that both types of confinement eventually lead to jamming.Comment: 21 pages, 14 figures. submitted to the Journal of Rheolog

Building capacity for dissemination and implementation research: One university’s experience

Abstract Background While dissemination and implementation (D&I) science has grown rapidly, there is an ongoing need to understand how to build and sustain capacity in individuals and institutions conducting research. There are three inter-related domains for capacity building: people, settings, and activities. Since 2008, Washington University in St. Louis has dedicated significant attention and resources toward building D&I research capacity. This paper describes our process, challenges, and lessons with the goal of informing others who may have similar aims at their own institution. Activities An informal collaborative, the Washington University Network for Dissemination and Implementation Research (WUNDIR), began with a small group and now has 49 regular members. Attendees represent a wide variety of settings and content areas and meet every 6 weeks for half-day sessions. A logic model organizes WUNDIR inputs, activities, and outcomes. A mixed-methods evaluation showed that the network has led to new professional connections and enhanced skills (e.g., grant and publication development). As one of four, ongoing, formal programs, the Dissemination and Implementation Research Core (DIRC) was our first major component of D&I infrastructure. DIRC’s mission is to accelerate the public health impact of clinical and health services research by increasing the engagement of investigators in later stages of translational research. The aims of DIRC are to advance D&I science and to develop and equip researchers with tools for D&I research. As a second formal component, the Washington University Institute for Public Health has provided significant support for D&I research through pilot projects and a small grants program. In a third set of formal programs, two R25 training grants (one in mental health and one in cancer) support post-doctoral scholars for intensive training and mentoring in D&I science. Finally, our team coordinates closely with D&I functions within research centers across the university. We share a series of challenges and potential solutions. Conclusion Our experience in developing D&I research at Washington University in St. Louis shows how significant capacity can be built in a relatively short period of time. Many of our ideas and ingredients for success can be replicated, tailored, and improved upon by others

Digital electron microscopic examination of human sural nerve biopsies

Diabetic peripheral polyneuropathy is characterized by axonal degeneration and regeneration as well as by Schwann cell and microvascular changes. These changes have been described at both the light (LM) and the electron microscopic (EM) levels; however, EM has not been applied to large clinical trials. Our goal was to adapt the rigorous techniques used for quantifying human biopsies with LM image analysis to accommodate ultrastructural analyses. We applied digital image capture and analysis to the ultrastructural examination of axons in sural nerve biopsies from diabetic patients enrolled in a multicenter clinical trial. The selection of sural nerve biopsies was based on the quality of specimen fixation, absence of physical distortion, and nerve fascicle size (≥100 000; ≤425 000 µm 2 ). Thin sections were collected on formvar-coated slot grids, stabilized with carbon and scanned on a Phillips CM100 transmission electron microscope. Digital images were captured with a Kodak Megaplus 1.6 camera. A montage was constructed using software derived from aerial mapping applications, and this virtual image was viewed by EM readers. Computer-assisted analyses included identification and labeling of individual axons and axons within regenerating clusters. The average density of regenerating myelinated axon clusters per mm 2 was 65.8 ± 5.1, range of 0–412 ( n  = 193). These techniques increase the number of samples that may be analyzed by EM and extend the use of this technique to clinical trials using tissue biopsies as a primary endpoint.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72529/1/j.1085-9489.2003.03030.x.pd

Study of aluminoborane compound AlB_4H_(11) for hydrogen storage

Aluminoborane compounds AlB_4H_(11), AlB_5H_(12), and AlB_6H_(13) were reported by Himpsl and Bond in 1981, but they have eluded the attention of the worldwide hydrogen storage research community for more than a quarter of a century. These aluminoborane compounds have very attractive properties for hydrogen storage: high hydrogen capacity (i.e., 13.5, 12.9, and 12.4 wt % H, respectively) and attractive hydrogen desorption temperature (i.e., AlB_4H_(11) decomposes at ~125 °C). We have synthesized AlB_4H_(11) and studied its thermal desorption behavior using temperature-programmed desorption with mass spectrometry, gas volumetric (Sieverts) measurement, infrared (IR) spectroscopy, and solid state nuclear magnetic resonance (NMR). Rehydrogenation of hydrogen-desorbed products was performed and encouraging evidence of at least partial reversibility for hydrogenation at relatively mild conditions is observed. Our chemical analysis indicates that the formula for the compound is closer to AlB_4H_(12) than AlB_4H_(11)

The role of Isocitrate Lyase (ICL1) in the metabolic adaptation of Candida albicans biofilms

Background A major characteristic of Candida biofilm cells that differentiates them from free-floating cells is their high tolerance to antifungal drugs. This high resistance is attributed to particular biofilm properties, including the accumulation of extrapolymeric substances, morphogenetic switching, and metabolic flexibility. Objectives This study evaluated the roles of metabolic processes (in particular the glyoxylate cycle) on biofilm formation, antifungal drug resistance, morphology, and cell wall components. Methods Growth, adhesion, biofilm formation, and cell wall carbohydrate composition were quantified for isogenic Candida albicans ICL1/ICL1, ICL1/icl1, and icl1/icl1 strains. The morphology and topography of these strains were compared by light microscopy and scanning electron microscopy. FKS1 (glucan synthase), ERG11 (14-α-demethylase), and CDR2 (efflux pump) mRNA levels were quantified using qRT-PCR. Results The ICL1/icl1 and icl1/icl1 strains formed similar biofilms and exhibited analogous drug-tolerance levels to the control ICL1/ICL1 strains. Furthermore, the drug sequestration ability of β-1, 3-glucan, a major carbohydrate component of the extracellular matrix, was not impaired. However, the inactivation of ICL1 did impair morphogenesis. ICL1 deletion also had a considerable effect on the expression of the FKS1, ERG11, and CDR2 genes. FKS1 and ERG11 were upregulated in ICL1/icl1 and icl1/icl1 cells throughout the biofilm developmental stages, and CDR2 was upregulated at the early phase. However, their expression was downregulated compared to the control ICL1/ICL1 strain. Conclusions We conclude that the glyoxylate cycle is not a specific determinant of biofilm drug resistance

Sampling Assemblages of Turtles in Central Illinois: A Case Study of Capture Efficiency and Species Coverage

Low and variable rates of capture are chronic problems in chelonian studies. We conducted a pilot study to evaluate protocols for future inventories of turtles in Illinois by comparing capture efficiency and species coverage for 2 devices (hoop net and cage trap), baits (fresh and day-old fish), habitats (lentic and lotic) and time periods . We accrued 402 captures of 378 individuals representing 7 species. At Sanganois State Fish and Wildlife Area (Sanganois), hoop nets produced more captures of more species (n = 231; 6 species) than cage traps (n = 119; 4 species). Statistical tests were equivocal for a reach of the Sangamon River, where both devices had 26 captures but hoop nets detected more species (n = 6) than cage traps (n = 3). At Sanganois, catch per unit effort varied with sampling session (time) and freshness of baits; one measure of species coverage varied with session. Results helped us make informed decisions about protocols for future inventories

Giant Alcohol: A Worthy Opponent for the Children of the Band of Hope

From its foundation in 1847, the temperance organisation the Band of Hope addressed its young members as consumers, victims, and agents. In the first two roles they encountered the effects of drink of necessity, but in the third role they were encouraged to seek it out, attempting to influence individuals and wider society against 'Giant Alcohol'. With an estimated membership of half the school-age population by the early twentieth century, well over three million, the Band of Hope also acted more directly to influence policy, and encouraged young people to consider issues of policy and politics. With its wide range of activities and material to educate, entertain and empower millions of children, and its radical view of the place of the child, the Band of Hope not only mobilised its child members to lobby for legal change, including prohibition, but took an active part in pointing out the cost of alcohol to society, particularly during the 14-18 war. The organisation began to decline post 1918, and this paper focuses on the address made to children by the Band of Hope in the late nineteenth and early twentieth centuries, at a time when its innovative view of children as able to understand and influence policy decisions reflected developments in the construction of childhood. This article draws on the archive of the British National Temperance League, over 50,000 items located in the Livesey Collection, University of Central Lancashire

Referral for menstrual problems:cross sectional survey of symptoms, reasons for referral, and management

OBJECTIVES: To describe the menstrual experience of women referred for menstrual problems, in particular menorrhagia (excessive menstrual loss), and to assess associations with reasons for referral given by their general practitioners, the women's understanding of the reasons for their attendance at the hospital clinics, and clinic outcome. DESIGN: Questionnaire survey, with partial review of case notes after 8 months. SETTING: Three hospital gynaecology clinics in Glasgow and Edinburgh. PARTICIPANTS: 952 women completed the questionnaire, and the first 665 were reviewed. OUTCOME MEASURES: Reason for referral, women's reported menstrual problems and reason for clinic attendance, diagnosis, and treatment. RESULTS: Only 38% (95% confidence interval 34% to 41%) of women reported excessive menstrual loss as a severe problem. However 60% (57-63%) gave it as reason for attending a clinic, and 76% (73-79%) of general practitioners gave it as reason for referral. Reason for referral was significantly biased towards bleeding (McNemar odds ratio 4.01, 3.0 to 5.3, P<0.001) and against pain (0.54, 0.4 to 0.7, P<0.001). Dysfunctional uterine bleeding was diagnosed in 37% (31-42%) of the 259 women who gave as reason for attendance something other than bleeding. Women who were economically disadvantaged differed in prevalence of the main diagnoses and were more likely to fail to reattend. Hysterectomy was associated with referral for bleeding (relative risk 4.9, 1.6 to 15.6, P<0.001) but not with the patient stating bleeding as the reason for clinic attendance. CONCLUSIONS: Intolerance of the volume of their bleeding is not a key feature among women attending clinics for bleeding problems. Broad menstrual complaint tends to be reframed as excessive bleeding at referral and during management. This may result in women receiving inappropriate care. Conceptualisation and assessment of menorrhagia requires reconsideration

Impact of Fiber Structure on the Material Stability and Rupture Mechanisms of Coronary Atherosclerotic Plaques

The rupture of an atherosclerotic plaque in the coronary circulation remains the main cause of heart attack. As a fiber-oriented structure, the fiber structure, in particular in the fibrous cap (FC), may affect both loading and material strength in the plaque. However, the role of fiber orientation and dispersion in plaque rupture is unclear. Local orientation and dispersion of fibers were calculated for the shoulder regions, mid FC, and regions with intimal thickening (IT) from histological images of 16 human coronary atherosclerotic lesions. Finite element analysis was performed to assess the effect of these properties on mechanical conditions. Fibers in shoulder regions had markedly reduced alignment (Median [interquartile range] 12.9° [6.6, 18.0], $p$ <0.05) compared with those in mid FC (6.1° [5.5, 9.0]) and IT regions (6.7° [5.1, 8.6]). Fiber dispersion was highest in shoulders (0.150 [0.121, 0.192]), intermediate in IT (0.119 [0.103, 0.144]), and lowest in mid FC regions (0.093 [0.081, 0.105], $p$ <0.05). When anisotropic properties were considered, stresses were significantly higher for the mid FC ($p$ = 0.030) and IT regions ($p$ = 0.002) and no difference was found for the shoulder or global regions. Shear (sliding) stress between fibers in each region and their proportion of maximum principal stress were: shoulder (25.8 kPa [17.1, 41.2], 12.4%), mid FC (13.9 kPa [5.8, 29.6], 13.8%), and IT (36.5 kPa [25.9, 47.3], 15.5%). Fiber structure within the FC has a marked effect on principal stresses, resulting in considerable shear stress between fibers. Fiber structure including orientation and dispersion may determine mechanical strength and thus rupture of atherosclerotic plaques. KThis research is supported by HRUK (RG2638/14/ 16), NSERC (6799-427538-2012), the WD Armstrong Trust, and the NIHR Cambridge Biomedical Research Centre