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The electrophoretic velocity of a sphere within a liquid-filled circular cylinder in a direction parallel to the cylinder axis has been studied by Yariv and Brenner (Phys. Fluids 2002, 14, 3354-3357; SIAM J. Appl. Math. 2003, 64, 423-441). We use their analyses of the electric field in order to determine the electrical force on the sphere along the cylinder radius (i.e., perpendicular to its axis) when either the radius of the sphere is small compared to that of the cylinder, or when the radius of the sphere is only slightly smaller than that of the cylinder. In both cases the force acts towards the centreline of the cylinder, and hence this force tends to stabilize electrophoresis of the sphere along the cylinder axis.

Objectives An international Nursing Leadership Collaborative covened in Japan to hold a patient safety and quality workshop for nursing students from six countries. The purpose was to measure students’ self reported beliefs reflecting sensitivity and openness to cultural diversity before and after the international experience. Methods A pre-post-test design was used and the Beliefs, Events, and Values Inventory was administered to international undergraduate and graduate nursing students. Results The group aggregate data analysis indicate that prior to the start of the workshop, the group presented itself as quite introspective and after the workshop the group reported being more sophisticated in making causal explanations about why the world works in the way it does. Conclusions Nursing students experienced an expanded awareness of their beliefs and values that reflect a greater degree of intercultural sensitivity for acceptance of inclusivity and diversity after the experience.

The insertion of an elastic rod or fiber into a confining cavity is studied. Such an insertion is a feature of a variety of problems, including packing and unpacking of DNA in viral capsids and the insertion of catheters during surgery. We consider a simplified geometry in which the container is a smooth (frictionless) circular cylinder of radius a. The fiber is pushed through a hole in the curved surface of the cylinder and is then assumed to stay in a cross-sectional plane perpendicular to the cylinder axis. A solution is found for the fiber shape in which most of the fiber lies against the curved interior surface of the cylinder, apart from the final end section of the fiber, of length 2.0888a, which crosses the interior of the cylinder before ending at the opposite side, which it meets at an angle 1.15 rad to the normal. The force required to push the fiber into the cylinder is EI/2a^{2}, where E is the fiber's Young's modulus and I its cross-sectional moment of inertia. The shape of the final end section of the fiber is confirmed by experiment.

To study how the 22q11.2 deletion predisposes to psychiatric disease, we generated induced pluripotent stem cells from deletion carriers and controls, as well as utilized CRISPR/Cas9 to introduce the heterozygous deletion into a control cell line. Upon differentiation into neural progenitor cells, we found the deletion acted in trans to alter the abundance of transcripts associated with risk for neurodevelopmental disorders including Autism Spectrum Disorder. In more differentiated excitatory neurons, altered transcripts encoded presynaptic factors and were associated with genetic risk for schizophrenia, including common (per-SNP heritability p (τc)= 4.2 x 10-6) and rare, loss of function variants (p = 1.29×10-12). These findings suggest a potential relationship between cellular states, developmental windows and susceptibility to psychiatric conditions with different ages of onset. To understand how the deletion contributed to these observed changes in gene expression, we developed and applied PPItools, which identifies the minimal protein-protein interaction network that best explains an observed set of gene expression alterations. We found that many of the genes in the 22q11.2 interval interact in presynaptic, proteasome, and JUN/FOS transcriptional pathways that underlie the broader alterations in psychiatric risk gene expression we identified. Our findings suggest that the 22q11.2 deletion impacts genes and pathways that may converge with risk loci implicated by psychiatric genetic studies to influence disease manifestation in each deletion carrier.

BackgroundSurvivors of critical illness often experience poor outcomes after hospitalisation, including delayed return to work, which carries substantial economic consequences.ObjectiveTo conduct a systematic review and meta-analysis of return to work after critical illness.MethodsWe searched PubMed, Embase, PsycINFO, CINAHL and Cochrane Library from 1970 to February 2018. Data were extracted, in duplicate, and random-effects meta-regression used to obtain pooled estimates.ResultsFifty-two studies evaluated return to work in 10 015 previously employed survivors of critical illness, over a median (IQR) follow-up of 12 (6.25–38.5) months. By 1–3, 12 and 42–60 months’ follow-up, pooled return to work prevalence (95% CI) was 36% (23% to 49%), 60% (50% to 69%) and 68% (51% to 85%), respectively (τ2=0.55, I2=87%, p=0.03). No significant difference was observed based on diagnosis (acute respiratory distress syndrome (ARDS) vs non-ARDS) or region (Europe vs North America vs Australia/New Zealand), but was observed when comparing mode of employment evaluation (in-person vs telephone vs mail). Following return to work, 20%–36% of survivors experienced job loss, 17%–66% occupation change and 5%–84% worsening employment status (eg, fewer work hours). Potential risk factors for delayed return to work include pre-existing comorbidities and post-hospital impairments (eg, mental health).ConclusionApproximately two-thirds, two-fifths and one-third of previously employed intensive care unit survivors are jobless up to 3, 12 and 60 months following hospital discharge. Survivors returning to work often experience job loss, occupation change or worse employment status. Interventions should be designed and evaluated to reduce the burden of this common and important problem for survivors of critical illness.Trial registration numberPROSPERO CRD42018093135.

Aim The aim of this study was to determine the perceptions of 14 novice nurse faculty of a 20-month experiential leadership academy on the leadership development. Background Managing the complexities of nursing faculty roles requires significant leadership skills that often are hard won. Evidence suggests that leadership preparation to prepare nursing faculty through guided mentoring can enhance faculty recruitment, satisfaction, and retention. Method Participants completed open-ended questions about their experiences in Sigma Theta Tau International's Nurse Faculty Leadership Academy. Results Data analysis revealed a meta-theme of "Finding Authentic Leadership Voice." Four subthemes emerged to shape the meta-theme: Identifying Inner Strengths and Areas for Improvement, Increasing Self-Confidence and Self-Awareness, Increasing Focus on Others, and Clarifying Aspirations for a Leadership Future. Conclusion Reflecting on their experiences, participants recognized changes in their leadership roles as they found an authentic voice that helped them persist and thrive amid the complexities of their faculty roles.

Kang et al. (J. Fluid Mech., vol. 874, 2019, pp. 339–358) studied viscous dissipation within a permeable body with a view to maximizing the damping of oscillations of the body. They found that dissipation is maximal when the length scale for diffusion of vorticity in the fluid outside the body is similar to the length scale for decay of fluid motion within the body. Their results are examined in the context of the simpler problem of a porous half-space oscillating parallel to the interface between porous solid and fluid. The analysis is then extended to consider the impulsive start-up from rest of a porous plane surface adjacent to unbounded fluid.

The electrical repulsion between two charged solid surfaces separated by an electrolyte is studied as a function of the permittivity ϵs of the solid in the limit in which potentials are small, and the gap between the plane solid surfaces is small compared to the Debye length κ-1 within the electrolyte. The solid surfaces are uniformly charged in a central region |x| 0, ions spill out over much larger O(L) regions, thereby reducing still further both the electrical potential between the solid surfaces and the repulsive force between them. However, this reduction becomes smaller as κL becomes large.

We assessed annual growth of Coregonus clupeaformis (Lake Whitefish) from a natural, lightly exploited population in a small lake in northern Maine using observed and back-calculated length-at-age data. We sampled Lake Whitefish from Clear Lake, ME, with gill nets and extracted otoliths from 57 fish. We incorporated age-at-length data into a von Bertalanffy growth function, which we employed to model growth trajectories from individual fish. We used these estimates to evaluate length-at-age variability within this population. Ages for Lake Whitefish varied from 8 y to 30 y. Among all fish, we characterized incremental growth by an average-growth coefficient of K = 0.156 and an estimated L∞ of 484 mm. The oldest individuals demonstrated the slowest incremental growth (K = 0.106) when compared to younger cohorts (K = 0.218). We observed an inverse relationship between L∞ and K and the estimated age-at-capture (R2 = 0.178 and 0.723, respectively), which suggests relatively slow growth and a smaller maximum size for the longest living members of the population. Our estimated parameters serve as a reference to inform management of populations of Lake Whitefish.

Large predatory fishes, capable of traveling great distances, can facilitate energy flow linkages among spatially separated habitat patches via extended foraging behaviors over expansive areas. Here, we tested this concept by tracking the movement of a large mobile estuarine fish, red drum (Sciaenops ocellatus). Specifically, we addressed the following two questions: (i) What are the spatial and temporal patterns of red drum movement (rates of dispersal) and activity space? (ii) Does red drum movement facilitate linkages among estuarine marsh complexes? Dispersal from the release location was greatest during the first 2 weeks at liberty before declining to less than 0.5 km·week–1 for the remainder of the study. Activity space initially increased rapidly before reaching an asymptote at 2.5 km2 2 weeks postrelease. Connectivity indices calculated among marsh complexes corroborated these observations, suggesting high residency and limited seascape-scale linkages via red drum movement behaviors. These data highlight potential within-estuary spatial structure for mobile fishes and could inform subsequent efforts to track energy flows in coastal food webs, predict the footprint of local habitat restoration benefits, and enhance the design of survey regimes to quantify overall population demography.

We investigate electrophoresis of a tightly fitting sphere of radius $R-h_{0}$ on the axis of a circular tube of radius $R$, using lubrication theory and ideas due to Schnitzer & Yariv (Phys. Fluids, vol. 26, 2014, 122002). The electrical charge clouds on both the cylindrical wall and the surface of the sphere are assumed thin compared to the gap between the sphere and cylinder, so that charge clouds do not overlap and ion exclusion effects are minimal. Nevertheless, non-uniform pumping of counter-ions within the charge clouds leads to a change in the ionic concentration outside the charge clouds in the narrow gap between sphere and cylinder. The electro-osmotic slip velocities at the two surfaces are modified, leading to a decrease in the electrophoretic velocity of the sphere at low Péclet numbers and an increase in the velocity at high Péclet numbers. When the field strength $E_{0}$ is low, it is known that the electrophoretic velocity $U_{0}$ is proportional to $E_{0}(\unicode[STIX]{x1D701}_{s}-\unicode[STIX]{x1D701}_{c})$ which is zero when the zeta potential $\unicode[STIX]{x1D701}_{s}$ on the sphere surface is equal to the zeta potential $\unicode[STIX]{x1D701}_{c}$ on the cylinder. The perturbation to the above low field strength electrophoretic velocity (at high Péclet number) is predicted to be proportional to $E_{0}^{3}(\unicode[STIX]{x1D701}_{s}+\unicode[STIX]{x1D701}_{c})^{2}(\unicode[STIX]{x1D70E}_{s}+\unicode[STIX]{x1D70E}_{c})$, where $\unicode[STIX]{x1D70E}_{s}$ and $\unicode[STIX]{x1D70E}_{c}$ are the surface charge densities on the sphere and cylinder. The choice of materials with similar or identical zeta potentials (and surface charge densities) for the cylinder and sphere should therefore facilitate the observation of velocities nonlinear in the field strength $E_{0}$, since the reference linear electrophoretic velocity will be small.

Life-history strategies often vary within motile marine species, affecting morphometry, growth, diet, and fecundity. Atlantic cod (Gadus morhua) in the Gulf of Maine display marked variation in a number of life-history traits, exemplified by differences in body colour. Migratory behaviours are suspected to differ among these colour types, but have yet to be shown definitively. Here, we used the combination of an acoustic telemetry system and fine-scale benthic habitat maps to reveal that the red phenotype cod adhered to an isolated kelp forest covering

Abiotic conditions greatly influence the distribution and abundance of marine organisms during early life-history phases. For instance, factors such as habitat heterogeneity often affect the dispersive phase of marine fishes, and then diminish in importance as species approach maturity and are influenced more so by biological processes. While recently settled fish are typically found in shallow, complex habitats such as seagrass beds, the degree to which juveniles associate with specific habitats as they grow and migrate into deeper water remains less clear. To better understand fish habitat preferences during early life-history phases, a literature review was conducted on habitat use by juvenile Atlantic cod (Gadus morhua), followed by an evaluation of the relationships between habitat characteristics and bottom trawl, video and hook-and-line data in the western Gulf of Maine. The review revealed that juvenile densities, survival, and growth rates were higher in structured than in less complex ha...

Background Internal medicine (IM) residents have previously been found to have significant knowledge and practice gaps in tuberculosis (TB) diagnosis, but it is unknown whether these gaps vary based on geography or TB incidence. San Francisco has the highest incidence of TB of any US city. UCSF IM residents encounter TB throughout their clinical training; however, the residency program does not have a dedicated TB curriculum. Following the Kern model of curriculum development, the aim of this project was to conduct a targeted needs assessment of UCSF IM residents regarding the need for and format of a TB curriculum. Methods An anonymous survey was sent to residents in February 2020 to assess their confidence in multiple domains in the diagnosis and management of latent and active pulmonary TB and gauge their preferences for the format and timing for delivery of a TB curriculum. All questions used a five-point Likert scale. Chi-squared test was used to compare confidence levels between interns and residents. The study received UCSF IRB approval. Results Seventy-five IM residents completed the survey (41% of residency; 32% interns and 68% residents). More than 50% of respondents reported that they were quite or extremely confident in only 1 of 14 domains assessed. Residents demonstrated significantly increased confidence compared to interns in only 4 of 14 domains. IM residents felt that a TB curriculum of a short video series, online videos interspersed with questions, or a house-staff handbook would be most useful, with more than 50% stating that these formats would be quite or extremely useful. While lectures and Powerpoint slides are common teaching methods, residents felt these formats were less useful. IM residents also felt they would be more likely to access a TB curriculum during ID elective or while caring for patients on wards and less likely on own time. Conclusion IM residents demonstrated lack of confidence in multiple domains in the diagnosis and management of latent and active pulmonary TB. Confidence did not markedly improve between interns and residents despite increased experience in a high TB incidence clinical setting, highlighting the need for a TB curriculum to address this gap. This curriculum should avoid lecture format and be integrated within relevant clinical time to maximize utility. Disclosures All Authors: No reported disclosures

Variability in life history traits and structural diversity of commercially exploited fishes in response to stress can impact their population dynamics and sustainability. Using data from a fishery dependent sampling program from 1978 to 2011, we evaluated temporal variability of size and growth of adult Atlantic herring (Clupea harengus) in the Gulf of Maine. We then developed and tested the hypotheses on the links of such temporal changes to population density and environmental factors and found decreases in size and growth potential. Generalized additive models found that density dependence was the main driver of such changes over sea surface temperature and salinity. Our results highlight the importance of density dependent processes in regulating growth and population size structure for Atlantic herring in the Gulf of Maine.

Atlantic cod (Gadus morhua) populations in the Gulf of Maine (GoM) are at a fraction of their historical abundance, creating economic hardships for fishermen and putting at risk the genetic diversity of the remaining populations. An understanding of the biocomplexity among GoM populations will allow for adaptive genetic diversity to be conserved to maximize the evolutionary potential and resilience of the fishery in a rapidly changing environment. We used restriction-site-associated DNA sequencing (RADseq) to characterize the population structure and adaptive genetic diversity of five spawning aggregations from the western GoM and Georges Bank. We also analyzed cod caught in the eastern GoM, an under-sampled area where spawning aggregations have been extirpated. Using 3,128 single nucleotide polymorphisms (SNPs), we confirmed the existence of three genetically separable spawning groups: (1) winter spawning cod from the western GoM, (2) spring spawning cod, also from the western GoM, and (3) Georges Bank cod. Non-spawning cod from the eastern GoM could not be decisively linked to either of the three spawning groups and may represent a unique component of the resource, a mixed sample, or cod from other unsampled source populations. The genetic differentiation among the three major spawning groups was primarily driven by loci putatively under selection, particularly loci in regions known to contain genomic inversions on linkage groups (LG) 7 and 12. These LGs have been found to be linked to thermal regime in cod across the Atlantic, and so it is possible that variation in timing of spawning in western GoM cod has resulted in temperature-driven adaptive divergence. This complex population structure and adaptive genetic differentiation could be crucial to ensuring the long-term productivity and resilience of the cod fishery, and so it should be considered in future management plans.

The decline of the Atlantic cod, Gadus morhua, stock in the Gulf of Maine to a historically low biomass has been coupled with a severe contraction in spatial range. The stock is now largely concentrated in the western Gulf of Maine. This erosion of spatial stock structure may be a factor-inhibiting recovery of Gulf of Maine cod. However, recent efforts to rebuild anadromous forage fish in the coastal Maine region coupled with the proposed creation of a new Eastern Maine Closed Area (EMCA), sited where localized depletion of the cod stock has been especially severe, might enable reestablishment of lost spatial structure of Gulf of Maine cod. We carried out larval transport modeling to examine the potential benefit of recovered cod spawning in the EMCA through supplying larvae to suitable juvenile settlement areas in the Gulf of Maine coastal zone and in the Cashes Ledge Closed Area (CLCA) in the central Gulf of Maine. The results indicate that an appreciable fraction of the larvae spawned in the EMCA are retained, to an age of settlement capability, in the coastal Maine region. Spawning in the EMCA may thus be a contributor of juveniles to a local, eastern Gulf of Maine, cod sub-stock. The results further indicate that spawning in the EMCA may supply a substantial subsidy of larvae to suitable juvenile habitat in the western Gulf of Maine and the CLCA. Protection of spawning stock in the EMCA may thus provide demographic benefits for the wider Gulf of Maine cod stock. Patterns of larval-stage connectivity between various potential spawning regions (including the EMCA) and areas of suitable juvenile habitat exhibit considerable interannual variability, which is predominantly linked to variability in the large-scale Gulf of Maine circulation. This result underscores the value of spatially explicit management as a means of fostering the recovery of the Gulf of Maine cod stock.

We describe a unique survey method that is able to cover a wide spatial and temporal range at a low cost. We utilised 10 individual small fishing vessels (lobster vessels) as acoustic research platforms to systematically survey a coastal population of Atlantic herring ( Clupea harengus) in the Gulf of Maine. We examined 38 transects spanning more than 200 miles of coastline. Due to the low cost of chartering the vessels, the survey was repeated weekly for nine weeks, resulting in over 2300 nautical miles of on-transect data. We calibrated single beam systems using a split beam guiding transducer to increase our confidence in the accuracy of the data and allow inter-ship comparisons. Although only one year of data has been analysed, the large spatial and temporal coverage of this survey provides preliminary information on herring population dynamics including spatial distribution throughout the survey area, timing of spawning and habitat associations of spawning aggregations. This survey will provide the template for longer term monitoring of herring spawning dynamics in Coastal Maine and how this may respond to climate and ocean variability.

Global Level of Connected Moisture (GLCM) and total moisture content (TMC) in porous over-layers on metals play a vital role in atmospheric corrosion. Using a model based on Kelvin condensation and Extended Hoshen-Kopelman algorithm these are computed as a function of relative humidity (RH) for 17 different over-layers with varying degrees of affinity to water. GLCM exhibits a critical RH (RH∗) but TMC does not. The computed RH∗ agrees with the experimental result for iron for selected model parameters. RH∗ values are computed for several metal oxide and polymer over-layers on metals in chloride-bearing and non-chloride-bearing atmospheres. RH∗ of chloride-bearing atmospheres is found to be less than that of non-chloride-bearing atmospheres. A new formula is advanced for time of wetness using GLCM. Using RH and temperature data obtained from India Meteorological Department for three cities, time of wetness (TOW) is computed for the 17 systems. These results are compared with the predictions of a simplistic formula presently available.

Preserving larger fish is often advocated as a conservation measure to help fish populations buffer environmental variation and fishing pressure. The rationale is that several size- and age-dependent reproductive traits confer a higher reproductive value to larger fish. The effects of variation in these reproductive traits on the dynamics of populations under various fishing patterns are however seldom evaluated. In this study, we develop a simulation model to evaluate how variation in three reproductive traits (fecundity–mass, hatching probability, and batch spawning) impacts the capacity of a fish population to withstand and recover from high fishing pressure. Biological functions of the model were calibrated based on the Gulf of Maine Atlantic cod stock, which is currently experiencing its lowest biomass level ever estimated. Results showed that variation in the shape of the fecundity–mass relationship had the most substantial impact on population resistance and recovery. Batch spawning and variation in hatching probability had limited impacts. Furthermore, results showed that preserving larger fish by imposing a slot fishery increased the resistance of the population to high fishing pressure, because it helped preserve the population reproductive potential determined by the high fecundity of large fish. The slot fishery, however, impeded population recovery, because it distributed the fishing pressure on intermediate-size classes which potential for biomass growth is maximal. This study underlines the importance of using precise size-dependent fecundity estimates when evaluating the productivity and sustainability of fisheries, as well as the importance of identifying priority among the components of population resilience (e.g. resistance or recovery) before implementing size-selective harvest strategies.

article i nfo The American lobster, Homarus americanus, is an important benthic consumer in the Gulf of Maine and supports anextremely valuable fishery in New England and eastern Canada. Meanwhile, there issubstantial interest in re- storing large predator fish species to the Gulf of Maine, and these predators may impact lobster populations both by consuming them and by inducing them to alter their behavior. Lobster tethering experiments were used to examine the susceptibility of a range of lobster size classes to predation in Saco Bay, Maine. The most susceptible sizes of lobsters were then exposed to three different fish predators (Atlantic striped bass Morone saxatilis, Atlantic cod Gadus morhua ,a nd sea ravenHemitripterus americanus) separately in experimental mesocosm tanks. Juvenile lobsters moved less and spent more time in shelter when in the presence of cod or sea raven. By contrast, striped bass did not induce lobsters to alter their behavior. Striped bass are highly mobile, active pursuit predators, which are thought to induce weaker behavioral responses in prey than sit-and-pursue predators like sea ravens. Thus, differences in lobster sheltering behavior corresponded with differences in predator foraging behavior. These predator-induced changes in behavior can result in less foraging activity, which may translate into reduced lobster growth and reproduction. Efforts to model marine communities and ecosystems will benefi tf rom am ore holistic understanding of whether predators induced prey to modify their foraging behavior and habitat usage.

The screened Coulomb interaction between a pair of infinite parallel planes with spatially varying surface charge is considered in the limit of small electrical potentials for arbitrary Debye lengths. A simple expression for the disjoining pressure is derived in terms of a two dimensional integral in Fourier space. The integral is evaluated for periodic and random charge distributions and the disjoining pressure is expressed as a sum over Fourier-Bloch reciprocal lattice vectors or in terms of an integral involving the autocorrelation function respectively. The force between planes with a finite area of uniform charge, a model for the DLVO interaction between finite surfaces, is also calculated. It is shown that the overspill of the charge cloud beyond the region immediately between the charged areas results in a reduction of the disjoining pressure, as reported by us recently in the long Debye length limit for planes of finite width., 26 pages, 4 figures

An approach is presented for estimating the retention of moisture and its distribution within porous bodies or layers. Corrosion will only occur if moisture above the oxide layer can be connected to the metal/oxide surface. Such local levels of connected moisture and global levels of connected moisture were computed using Monte Carlo simulation as a function of depth in the porous body for several values of percolation parameter P which in turn depends on relative humidity (RH) and temperature (T). The time that an oxide on a metal surface holds connected moisture paths is compared to times that a smooth surface will retain moisture films. The implications for corrosion are discussed.

American lobster (Homarus americanus) landings have more than quadrupled in the last two decades (1990–2010), coinciding with the collapse of Gulf of Maine groundfish fisheries such as Atlantic cod (Gadus morhua). Recently there has been speculation that the release of lobster from predatory control may have resulted in both lower predation rates and increased foraging areas. We used fine-scale acoustic telemetry within a 200 m × 250 m field enclosure to test the hypothesis that cod induce lobsters to decrease movement and seek refuge. We found a large amount of variation in the behavioral response of individual lobsters to predators; however, the addition of cod into the enclosure reduced maximum daily home range area and significantly reduced the distance traveled from shelter habitat area for all individuals. When predators were removed from the enclosure, lobsters responded by increasing home range area and significantly increasing the distance traveled from shelter habitat area. These results represent the first experimental evidence for American lobster range contraction and subsequent expansion in the presence and absence of cod, respectively.

The screened Coulomb interaction between uniformly charged flat plates is considered at very small plate separations for which the Debye layers are strongly overlapped, in the limit of small electrical potentials. If the plates are of infinite length, the disjoining pressure between the plates decays as an inverse power of the plate separation. If the plates are of finite length, we show that screening Debye layer charges close to the edge of the plates are no longer constrained to stay between the plates, but instead spill out into the surrounding electrolyte. The resulting reduction in the disjoining pressure is calculated analytically. A similar reduction of disjoining pressure due to loss of lateral confinement of the Debye layer charges should occur whenever the sizes of the interacting charged objects become small enough to approach the Debye scale. We investigate the effect here in the context of a two dimensional model problem that is sufficiently simple to yield analytical results., Comment: 15 pages, 5 figures

A theoretical analysis of the generation of electrical streaming currents and electrical power by two-phase flow in a rectangular capillary is presented. The injection of a second, non-conducting fluid phase tends to increase the internal electrical resistance of the electrical generator, thereby increasing the power output. If the viscosity of the injected fluid is large, the resulting high shear rate in the low-viscosity fluid at the wall generates a large streaming current and the power generated is further enhanced. However, if the injected fluid viscosity is low, the wall shear rate in the more viscous suspending fluid is reduced, as are streaming currents. Power generation would be small but for capillary effects at the ends of the bubbles that increase the pressure drop along the capillary above that expected for annular flow.

The final stages of draining of a rapidly rotating axisymmetric container are considered. The film of fluid coating the container wall is assumed sufficiently thin so that it rotates at the same angular velocity as the container and is flung outwards by centrifugal forces. The optimal shape that minimises the volume of the fluid film (for a given volume of container) is found for a non-Newtonian fluid with a power-law rheology. The optimal shapes have larger diameter, and are shallower, than the equivalent optimal shapes for gravitational draining. This larger diameter increases the effectiveness of the centrifugal forces. The optimal shape for a shear thinning fluid (with power law index n 1 ) is wider and shallower than for Newtonian ( n = 1 ) or shear thickening ( n > 1 ) fluids.

Inviscid irrotational flow around a pair of coaxial disks is considered in the limit in which the distance 2h between the disks is small compared to their radius a. The disks have zero thickness and accelerate away from one another along their common axis. The added mass M of each accelerating disk is increased by the presence of the other disk. Analytic predictions are obtained when h/a ≪ 1, with M ~ πa/(8h)-ln(h/a)/2+0.77875+. . . The term O(a/h) can be obtained by means of an inviscid analysis of approximately unidirectional flow within the gap between the disks, but the correction terms have not been reported previously. The irrotational flow problem satisfies Neumann boundary conditions on the surface of the disks, but is otherwise analogous to the Dirichlet problem of the capacitance of a pair of charged disks, which has been the subject of much study and controversy.

The purpose of this study was to examine whether Socioscientific Issues (SSI) based learning environments affect university students’ epistemological understanding of scientific inquiry differently from traditional science educational contexts. We identify and compare conceptions of scientific inquiry of students participating in an interdisciplinary, SSI-focused undergraduate human biology major (SSI) and those participating in a traditional biology major (BIO). Forty-five SSI students and 50 BIO students completed an open-ended questionnaire examining their understanding of scientific inquiry. Eight general themes including approximately 60 subthemes emerged from questionnaire responses, and the numbers of students including each subtheme in their responses were statistically compared between groups. A subset of students participated in interviews, which were used to validate and triangulate questionnaire data and probe students’ understanding of scientific inquiry in relation to their majors. We found that both groups provided very similar responses, differing significantly in only five subthemes. Results indicated that both groups held generally adequate understandings of inquiry, but also a number of misconceptions. Small differences between groups supported by both questionnaires and interviews suggest that the SSI context contributed to nuanced understandings, such as a more interdisciplinary and problem-centered conception of scientific inquiry. Implications for teaching and research are discussed.

The reliability of population dynamics and stock assessment models hinges on accurate life-history information. Mark-recapture studies represent a commonly used technique to investigate crustacean growth, mortality, and migrations. We evaluated tagging by coded microwire tags for the American lobster, Homarus americanus H. Milne Edwards, 1837, in a controlled study to determine tag retention and any influence on growth increment, intermolt duration, or survival. Microwire tags were injected into the propodus of the second right walking leg and two size classes (12-19.6 and 19.7-30 mm carapace length [CL]) were tested by two individual taggers. Overall tag retention was 96%. Tag retention after first ecdysis was 95% for the 12-19.6 mm CL and 92.5% for the 19.7-30 mm CL size class. There was no significant difference in tag retention between taggers, growth between tagged and untagged lobsters, or intermolt duration between tagged and untagged lobsters (P > 0.05 for all tests). Tag-induced mortality did not occur. These results support the further use of coded microwire tags to explore life-history variables for juvenile lobsters in the wild.

Squeeze flow in the gap between non-parallel circular plates of radius R is discussed. The test material is assumed to be a power-law fluid, with a no-slip boundary condition at the plates. If the mean separation between the plates is h , and the angle of inclination between the plates is ϕ ≪ h / R , the force on the plates is perturbed only at O ( ϕ 2 ) and is increased by less than 10% if ϕ h / R . A torque O ( ϕ ) tends to return the plates to a parallel configuration.

The resistive pulse method based on measuring the ion current trace as a biomolecule passing through a nanopore has become an important tool in biotechnology for characterizing molecules. A detailed physical understanding of the translocation process is essential if one is to extract the relevant molecular properties from the current signal. In this Perspective, we review some recent progress in our understanding of hydrodynamic flow and transport through nanometer sized pores. We assume that the problems of interest can be addressed through the use of the continuum version of the equations of hydrodynamic and ion transport. Thus, our discussion is restricted to pores of diameter greater than about ten nanometers: such pores are usually synthetic. We address the fundamental nanopore hydrodynamics and ion transport mechanisms and review the wealth of observed phenomena due to these mechanisms. We also suggest future ionic circuits that can be synthesized from different ionic modules based on these phenomena and their applications.

We put forward a combined observing and modeling strategy for evaluating effects of environmental forcing on the dynamics of spatially structured cod populations spawning in the western Gulf of Maine. Recent work indicates at least two genetically differentiated complexes in this region: a late spring spawning, coastal population centered in Ipswich Bay, and a population that spawns in winter inshore and on nearshore banks in the Gulf of Maine and off southern New England. The two populations likely differ in trophic interactions and in physiological and behavioral responses to different winter and spring environments. Coupled physical–biological modeling has advanced to the point where within-decade forecasting of environmental conditions for recruitment to each of the two populations is feasible. However, the modeling needs to be supported by hydrographic, primary production and zooplankton data collected by buoys, and by data from remote sensing and fixed station sampling. Forecasts of environmentally driven dispersal and growth of planktonic early life stages, combined with an understanding of possible population-specific predator fields, usage of coastal habitat by juveniles and adult resident and migratory patterns, can be used to develop scenarios for spatially explicit population responses to multiple forcings, including climate change, anthropogenic impacts on nearshore juvenile habitat, connectivity among populations and management interventions such as regional fisheries closures.

Sherwood, G. D., and Grabowski, J. H. 2010. Exploring the life-history implications of colour variation in offshore Gulf of Maine cod (Gadus morhua). – ICES Journal of Marine Science, 67: 1640–1649. The evolution of alternative life-history strategies in fish has largely been overlooked by fisheries managers, although differences in the biology of life-history variants can have important implications for the scale and productivity of fisheries. Cod display strikingly variable colouration in the Gulf of Maine, with red- and olive-coloured cod found in close sympatry. Colour types from Cashes Ledge, a shallow, offshore (∼100 km) feature, are examined to see whether they differ in key life-history traits including diet, depth distribution, growth, and body morphology. Red cod consumed significantly more crabs, lobsters, and demersal fish, whereas olive cod consumed more shrimp. Stable carbon isotope signatures (δ13C) varied significantly among colour types, but are thought to reflect baseline differences in δ13C at Cashes Ledge (potentially useful for residence estimates). Red cod were confined to a small area of shallow water (

The electrical streaming potential generated by a two-phase pressure-driven Stokes flow in a cylindrical capillary is computed numerically. The potential difference ΔΦ between the two ends of the capillary, proportional to the pressure difference Δp for single-phase flow, is modified by the presence of a suspended drop on the centreline of the capillary. We determine the change in ΔΦ caused by the presence of an uncharged insulating neutrally buoyant drop at a small electric Hartmann number, i.e. when the perturbation to the flow field caused by electric stresses is negligible.The drop velocity and deformation, and the consequent changes in the pressure difference Δp and streaming potential ΔΦ, depend upon three independent parameters: the size a of the undeformed drop relative to the radius R of the capillary; the viscosity ratio λ between the drop phase and the continuous phase; and the capillary number Ca which measures the ratio of viscous to capillary forces. We investigate how the streaming potential depends on these parameters: purely hydrodynamic aspects of the problem are discussed by Lac & Sherwood (J. Fluid Mech., doi:10.1017/S0022112009991212).The potential on the capillary wall is assumed sufficiently small so that the electrical double layer is described by the linearized Poisson–Boltzmann equation. The Debye length characterizing the thickness of the charge cloud is taken to be small compared with all other length scales, including the width of the gap between the drop and the capillary wall. The electric potential satisfies Laplace's equation, which we solve by means of a boundary integral method. The presence of the drop increases |ΔΦ| when the drop is more viscous than the surrounding fluid (λ > 1), though the change in |ΔΦ| can take either sign for λ < 1. However, the difference between ΔΦ and Δp (suitably non-dimensionalized) is always positive. Asymptotic predictions for the streaming potential in the case of a vanishingly small spherical droplet, and for large drops at high capillary numbers, agree well with computations.