Intermediate Density Research Articles

Effects of first intermediate host density, host size and salinity on trematode infections in mussels of the south-western Baltic Sea.

Trematode prevalence and abundance in hosts are known to be affected by biotic drivers as well as by abiotic drivers. In this study, we used the unique salinity gradient found in the south-western Baltic Sea to: (i) investigate patterns of trematode infections in the first intermediate host, the periwinkle Littorina littorea and in the downstream host, the mussel Mytilus edulis, along a regional salinity gradient (from 13 to 22) and (ii) evaluate the effects of first intermediate host (periwinkle) density, host size and salinity on trematode infections in mussels. Two species dominated the trematode community, Renicola roscovita and Himasthla elongata. Salinity, mussel size and density of infected periwinkles were significantly correlated with R. roscovita, and salinity and density correlated with H. elongata abundance. These results suggest that salinity, first intermediate host density and host size play an important role in determining infection levels in mussels, with salinity being the main major driver. Under expected global change scenarios, the predicted freshening of the Baltic Sea might lead to reduced trematode transmission, which may be further enhanced by a potential decrease in periwinkle density and mussel size.

Do Female Songbirds Avoid a Mammalian Nest Predator When Selecting Their Nest Site?

Perceived predation risk can elicit strong behavioral responses in potential prey. During nest building, songbirds exhibit anti-predator behaviors under experimental conditions. Here, we hypothesized that females of two ground-nesting songbird species, the Ovenbird (Seiurus aurocapilla) and the Hermit Thrush (Catharus guttatus), would use naturally available cues of predation risk when selecting their nest site, thereby avoiding activity hotspots of Eastern Chipmunks (Tamias striatus), a predator on songbird nests and fledglings. Chipmunks are highly vocal, thus providing cues of their presence. We mapped chipmunk detections and songbird nests over four successive years in study plots located in mature deciduous forest of New Brunswick, Canada. Chipmunk activity varied by an order of magnitude among study plots and years. Nests were built further away from chipmunk detections than expected by chance in some, but not all, plot-year combinations. When comparing study plots, the proportion of nests built within hotspots of chipmunk activity was four times lower in the two plots where chipmunk activity was highest. Yet, we did not find clear evidence that chipmunk avoidance provided fitness benefits, possibly because this behavior procured little protection at high chipmunk densities. The persistence of this avoidance behavior in our focal species of ground-nesting songbirds might be linked to the benefits it procures at intermediate chipmunk densities.

Partial synchronisation of glycolytic oscillations in yeast cell populations

The transition between synchronized and asynchronous behaviour of immobilized yeast cells of the strain Saccharomyces carlsbergensis was investigated by monitoring the autofluorescence of the coenzyme NADH. In populations of intermediate cell densities the individual cells remained oscillatory, whereas on the level of the cell population both a partially synchronized and an asynchronous state were accessible for experimental studies. In the partially synchronized state, the mean oscillatory frequency was larger than that of the cells in the asynchronous state. This suggests that synchronisation occurred due to entrainment by the cells that oscillated more rapidly. This is typical for synchronisation due to phase advancement. Furthermore, the synchronisation of the frequency of the glycolytic oscillations preceded the synchronisation of their phases. However, the cells did not synchronize completely, as the distribution of the oscillatory frequencies only narrowed but did not collapse to a unique frequency. Cells belonging to spatially denser clusters showed a slightly enhanced local synchronisation during the episode of partial synchronisation. Neither the clusters nor a transition from partially synchronized glycolytic oscillations to travelling glycolytic waves did substantially affect the degree of partial synchronisation. Chimera states, i.e., the coexistence of a synchronized and an asynchronous part of the population, could not be found.

Effect of Different Irradiation Modes of Azulene-mediated Photodynamic Therapy on Singlet Oxygen and PGE2 Formation.

Azulene samples in ethanol/distilled water (1, 10 and 100µm) were irradiated with a 638nm red laser (0.5 watts, light-to-target distance 2cm, energy density 4 or 40Jcm-2 ) by either continuous, fractionation or pulse mode. Singlet oxygen in the samples was measured using 10µm 9,10-dimethyl anthracene (positive control 10μm erythrosine) and relative fluorescence intensities were measured at 375/436nm excitation/emission. Peripheral blood mononuclear cells (PBMCs, 1×105 cells/well) preincubated with 0.01μgmL-1 rhTNF-α for 6h were cultured with irradiated azulene samples in RPMI-1640 under standard conditions. PGE2 was quantified by rhPGE2 ELISA kit using a Varioscan® microplate reader at an excitation wavelength of 420nm. Kruskal Wallis with Dunn`s test was performed at a significance level of P<0.05. The highest singlet oxygen amount was found in 10µm azulene samples irradiated at 40Jcm-2 under continuous mode (P=0.001 when compared with 10µm erythrosine). PGE2 expression in rhTNF-α-induced PBMCs was reduced to 45% of control by 1µm azulene irradiated at 40Jcm-2 under fractionation mode. Fractionation mode with intermediate laser energy density in the presence of low concentration of azulene could increase singlet oxygen and tend to reduce PGE2 .

Heparin Induced Thrombocytopenia in Patients with COVID-19

BackgroundThe Coronavirus disease-2019 (COVID-19) is a global pandemic caused by novel coronavirus SARS-CoV-2. Acute respiratory and renal failure as well as systemic coagulopathy are critical aspects of the morbidity and mortality in patients with COVID-19. Heparin Induced Thrombocytopenia (HIT) occurs when IgG antibodies form against platelet factor 4-Heparin complex, resulting in platelet activation and removal, leading to a prothrombotic state. HIT is suspected when there is a platelet count decrease of more than 50% after exposure to heparin, along with hypercoagulability. Clinical Scoring systems like 4T Score (Thrombocytopenia, Timing, Thrombosis, no other cause of Thrombocytopenia) have been developed to assess the pretest probability of HIT. The use of unfractionated heparin, post-orthopedic and post-cardiac surgery state, female gender, and old age are recognized as risk factors for HIT. There is a nine-fold increased risk of developing HIT in patients requiring hemodialysis. ICU patients and patients with VTE without thrombocytopenia are considered to have low pre-test probability for HIT. Studies have shown that only 6% who are investigated serologically for HIT actually have the diagnosis. We conducted this study to assess the incidence and risk factors for HIT in COVID-19 positive patients and its impact on mortality.MethodsA retrospective analysis was performed on all patients who were COVID-19 positive and hospitalized between March 1, 2020 and June 26, 2020 at our institution. Patients with intermediate or high suspicion for HIT, based on 4T score of 4 or higher, underwent IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA). Washed platelet assays such as serotonin release assay (SRA) and heparin-induced platelet aggregation (HIPA) were used as confirmatory tests in cases with intermediate or low optical density (OD) with EIA. The incidence of HIT, its impact on mortality, and positivity of IgG-specific PF4-EIA in COVID-19 patients were studied, and statistical analysis was done with X2 testing. Subgroup analysis was performed based on demographic factors and risk factors for HIT, including exposure to heparin or low molecular weight heparin (LMWH), history of or cancer, recent orthopedic or cardiac surgery, exposure to renal replacement therapy (RRT), and severity of disease (D-dimer >6 ULN, Acute Kidney Injury, ICU admission, and mechanical ventilation requirement). These factors were analyzed by Fisher’s exact test to determine their impact on mortality. The hospital course for HIT antibody-positive patients was further analyzed to study the impact of COVID-19 related therapy, such as Remdesivir, Tocilizumab, Hydroxychloroquine, Steroids, and anticoagulation after diagnosis of HIT.ResultsWEight out of 1265 hospitalized COVID-19 positive patients tested positive for IgG-specific platelet factor 4(PF4)-dependent enzyme immune assay (EIA+). Incidence of EIA+ in COVID-19 patients was 0.6%, which is significantly higher than in the general population 0.2% (p<.0001, 95% CI 0.25-1.20%). The incidence of thromboembolic events in EIA+ patients was 87.5%, significantly higher than the rate of 10.90% in all COVID-19 patients (p<.0001, CI 41.96- 86.98%). The mortality rate in EIA+ patients was 50%, significantly greater than the mortality rate of 12% in all hospitalized COVID-19 patients (p=.0011, CI 9.46-66.53). Serological confirmation of HIT diagnosis was 37.5% (2 had OD>1, 1 was SRA positive) which is significantly higher than confirmation of HIT in nonCOVID-19 patients 6% (p<.0001, 95% CI 29.57-85.32%). All 3 confirmed HIT patients (100%) had severe disease (3/3 required ICU admission, 2/3 required mechanical ventilation, the one not requiring mechanical ventilation required RRT).ConclusionOur study indicates incidence of HIT is higher in the COVID-19 population. The incidence of positive EIA for patients with intermediate to high 4T scores is also higher in COVID-19 positive patients. This can be attributed to the cytokine storm and severe sepsis seen in critically ill COVID-19 patients. Our study also suggests that development of HIT can contribute to increased risk for thromboembolic events as well as mortality of COVID-19 patients, however, our study is limited due to small sample size. Therefore, prospective studies are needed to analyze the impact of HIT on morbidity, mortality and long-term outcomes in COVID-19 patients.TableDisclosuresNo relevant conflicts of interest to declare.

Experimental study on the elderly’s walking speed considering smoke density and visual acuity in buildings

To clarify the effect of visual acuity on walking speed of the elderly in the smoke-filled environment of the building, their walking speed was measured. 37 older people were selected to participate in the experiments, and their characteristics were counted, including visual acuity, height, age, and gender before the experiments. Walking speed in the smoke-free environment was also measured. The smoke density was divided into five stages from thin to thick, and each elderly person was measured three times at the same stages. The results showed that the walking speed of the elderly was divided into three stages according to the smoke density. The walking speed in the thin smoke environment is basically the same as that in the smoke-free environment. The walking speed reduces by 0.31 m/s as the extinction coefficient increases by 1 m−1 in intermediate smoke density. And in the thick smoke, walking speed reduced to 0.27 m/s. Visual acuity dominates walking speed in the smoke-filled environment, but other factors play a leading role in walking speed in the smoke-free environment. Besides, a calculation model is proposed which can predict the walking speed of the elderly by visual acuity and smoke density. This model can help to predict walking speed and evacuation process of the elderly in fire and provide a reliable basis for the performance-based design of buildings.

Master sintering curve and activation energy of sintering of ZrO2-doped Al2O3

Master sintering curve (MSC) was used to make an estimation of the apparent activation energies of undoped Al2O3 and ZrO2-doped Al2O3 samples in the intermediate density range (60–83%). ZrO2 at low concentrations of 2000 ppm and 5000 ppm were used for doping Al2O3. Dilatometric studies were performed using three different heating rates (5, 7.5, and 10 °C/min) on undoped and ZrO2-doped Al2O3 samples to construct the MSCs. The validity of the MSCs was verified by experimental runs on the undoped and doped Al2O3 compacts. The apparent activation energies of Al2O3 was found to be 539 kJ/mol, and the same for the ZrO2-doped Al2O3 samples were 670 kJ/mol (for 2000 ppm doping) and 790 kJ/mol (for 5000 ppm doping), respectively. The effects of the low concentrations of ZrO2 on the densification behaviour and activation energy of sintering of Al2O3 were underpinned.

Topology optimization of multiphase materials with dynamic and static characteristics by BESO method

The demand for advanced manufacturing is gradually turning to the multi-functional integrated structure, so the effective and innovative functional structure topology optimization design method can maximize the performance of the structure. This paper proposes a parallel topology optimization design method for dynamic and static characteristics of multiphase materials. The inherent discrete design variables of bidirectional evolutionary structure optimization (BESO) can clearly distinguish the topological boundaries of multiphase materials without the intermediate density materials. The pre-processing density filtering scheme is introduced into the BESO method to eliminate the numerical calculation instability problem. Then, the improved multiphase materials interpolation scheme can overcome the local modal phenomenon of vibration problems. Finally, a series of typical numerical examples show that the method is effective, efficient and easy to implement in multiphase materials topology optimization with dynamic and static characteristics.

Temporal trends of physician geographical distribution and high and intermediate physician density areas and factors related to physicians’ movement to low physician density areas in Japan: a longitudinal study (1996–2016)

ObjectivesA major issue in Japan’s health policy is the geographical maldistribution of physicians. This study aimed to analyse temporal trends in the geographical distribution of physicians and analyse physicians in...

‘Gigante’ cactus pear cultivated at different population densities in a mechanizable arrangement

ABSTRACT Cactus pear is a crop adapted to the climatic conditions of the Brazilian semiarid region, so it has contributed to the socioeconomic development of this region. The objective of this study was to evaluate the response of ‘Gigante’ cactus pear cultivated at different population densities in a mechanizable arrangement. The experimental design was in randomized blocks, with six population densities: 22,857; 34,286; 51,428; 62,857; 80,000 and 95,000 plants ha-1 and four repetitions. The following variables were evaluated: plant height, number of cladodes, cladode length, cladode width and cladode area index, green and dry matter yields, extraction/export of nutrients and soil chemical characteristics. Increase in population density in a mechanizable arrangement decreases the number of cladodes and increases the cladode area index. The maximum green and dry matter yield of cactus pear cultivated in arrangement that allows mechanization is expected with populations of 69,111.79 and 64,445.91 plants ha-1, respectively. Maximum values of extraction/export of nutrients in cactus pear tissue are expected at intermediate population densities (62,721.52-74,741.93 plants ha-1). Soil potential acidity has maximum value with 64,525.51 plants ha-1.

Predicting human-carnivore conflict at the urban-wildland interface

A major threat to mammalian carnivores is death due to human conflict, including carnivore use of anthropogenic food sources, predation of livestock, or car accidents. To reduce conflicts, it is critical to target proactive mitigations using reliable evidence on where conflict is likely to occur. We tested hypotheses about the importance of anthropogenic and environmental predictors in explaining the timing and distribution of human conflict with black bears (Ursus americanus) and cougars (Puma concolor) in a North American hotspot of human-carnivore conflict. Using reported conflict locations and spatial data in use-availability models, we estimated and mapped the probability of conflict for both species, including seasonally for bears, between 2011 and 2017. We found conflict increased for both species along the urban-wildland interface. Conflict with black bears was present in all seasons and increased with intermediate human density (i.e. suburban neighbourhoods). However, in autumn, bear conflict was more common in agricultural areas. Conversely, cougar conflict was primarily in rural areas, as their main attractant was livestock. We recommend targeting areas and times of expected conflict with proactive mitigations, such as bear-resistant garbage bins in communities adjacent to forests, electric fences that deter both carnivore species, and elimination of rural food attractants in autumn.

Sub-surface current meanders along the Namibian shelf

The influence of long, sub-inertial waves travelling poleward on spatiotemporal fluctuations in the hydrography of coastal upwelling areas has widely been discussed theoretically in the literature since the late 1970s. In this paper, in contrast, measured unexpected wave-like changes in the intermediate density field along the Namibian continental slope are presented and suggested to be the result of a geostrophically adjusted southward current with significant on-offshore meanders. Hydrographic measurements had been carried out on board of r/v ‘METEOR’ along the 200-m isobath above the Namibian continental shelf (19–23 °S) during seven days in October/November 2000. Measured water properties rhythmically change in space between oceanic (on-shore meander, well oxygenated, dominant Eastern South Atlantic Central Water, ESACW) and coastal waters (off-shore meander, poorly oxygenated, dominant South Atlantic Central Water, SACW). The first case is accompanied by downward displacements of the permanent pycnocline, while the second one corresponds to the opposite situation. The distance between these rather periodic along-section changes in stratification is roughly constant and estimated to be about 60 km. At two hydrographic station positions, duplicate measurements enable an estimation of the associated southward propagation speed of the signal. The obtained value of about 0.16 m/s roughly peaks at the pressure level of about 70 dbar, and the corresponding time scale is estimated to be a few days.

Dust coagulation feedback on magnetohydrodynamic resistivities in protostellar collapse

Context. The degree of coupling between the gas and the magnetic field during the collapse of a core and the subsequent formation of a disk depends on the assumed dust size distribution. Aims. We study the impact of grain–grain coagulation on the evolution of magnetohydrodynamic (MHD) resistivities during the collapse of a prestellar core. Methods. We use a 1D model to follow the evolution of the dust size distribution, out-of-equilibrium ionisation state, and gas chemistry during the collapse of a prestellar core. To compute the grain–grain collisional rate, we consider models for both random and systematic, size-dependent, velocities. We include grain growth through grain–grain coagulation and ice accretion, but ignore grain fragmentation. Results. Starting with a Mathis-Rumpl-Nordsieck (MRN) size distribution (Mathis et al. 1977, ApJ, 217, 425), we find that coagulation in grain–grain collisions generated by hydrodynamical turbulence is not efficient at removing the smallest grains and, as a consequence, does not have a large effect on the evolution of the Hall and ambipolar diffusion MHD resistivities, which still drop significantly during the collapse like in models without coagulation. The inclusion of systematic velocities, possibly induced by the presence of ambipolar diffusion, increases the coagulation rate between small and large grains, removing small grains earlier in the collapse and therefore limiting the drop in the Hall and ambipolar diffusion resistivities. At intermediate densities (nH ~ 108 cm−3), the Hall and ambipolar diffusion resistivities are found to be higher by 1 to 2 orders of magnitude in models with coagulation than in models where coagulation is ignored, and also higher than in a toy model without coagulation where all grains smaller than 0.1 μm would have been removed in the parent cloud before the collapse. Conclusions. When grain drift velocities induced by ambipolar diffusion are included, dust coagulation happening during the collapse of a prestellar core starting from an initial MRN dust size distribution appears to be efficient enough to increase the MHD resistivities to the values necessary to strongly modify the magnetically regulated formation of a planet-forming disk. A consistent treatment of the competition between fragmentation and coagulation is, however, necessary before reaching firm conclusions.

The limits of Riemann solutions to Euler equations of compressible fluid flow with a source term

In this paper, we investigate the limits of Riemann solutions to the Euler equations of compressible fluid flow with a source term as the adiabatic exponent tends to one. The source term can represent friction or gravity or both in Engineering. For instance, a concrete physical model is a model of gas dynamics in a gravitational field with entropy assumed to be a constant. The body force source term is presented if there is some external force acting on the fluid. The force assumed here is the gravity. Different from the homogeneous equations, the Riemann solutions of the inhomogeneous system are non self-similar. We rigorously proved that, as the adiabatic exponent tends to one, any two-shock Riemann solution tends to a delta shock solution of the pressureless Euler system with a Coulomb-like friction term, and the intermediate density between the two shocks tends to a weighted $$\delta $$ -mesaure which forms the delta shock; while any two-rarefaction-wave Riemann solution tends to a two-contact-discontinuity solution of the pressureless Euler system with a Coulomb-like friction term, whose intermediate state between the two contact discontinuities is a vacuum state. Moreover, we also give some numerical simulations to confirm the theoretical analysis.

Relating the Flow Processes and Bedforms of Steady-State and Waning Density Currents

© Copyright© 2020 de Cala, Ohata, Dorrell, Naruse, Patacci, Amy, Simmons, McLelland and McCaffrey. The interaction between turbidity currents and mobile substrates can lead to the development of different types of bedforms. Although much research has been conducted on bedform development beneath open channel flows, research into bedform development beneath waning gravity currents is relatively rare. Analysis of density current-related bedform development has therefore relied upon open channel flow phase diagrams. We report on an experimental study designed to assess the development of bedforms under steady and waning saline density currents. The experimental density currents developed stepped density profiles in which a higher-density basal zone was separated from the ambient fluid by a zone of intermediate density; any bedforms that developed were contained within the bottom layer of the current. Under different conditions ripples, dunes, downstream migrating antidunes and long wavelength antidunes were observed to form and could be distinguished based on their interactions and phase relationships with the upper surface of the lower denser layer of the current. Due to limited mixing between the upper and lower layer of the current and maintenance of current momentum, currents set with slowing discharge flow rates maintained a steady flow velocity in the lower layer of the flow. As a result, sustained bedform formative conditions were achieved within this lower layer, while waning current conditions effected the rest of the flow. Under waning currents, it was seen how pre-existing bed states can determine the subsequent evolution of bedforms. This illustrates the limitations of existing phase diagrams as they do not account for trajectory or rate of passage of flows through different bedform phase spaces. In order to establish a reliable quantitative association between the flow regime and the type of bedform development, it is critical to adopt an appropriate Froude number calculation method for stratified flow. The updated density current phase diagram indicates supercritical flow can be achieved at lower flow velocities than for open channel flows due to the effects of reduced gravity. Bedform depositional structures found in outcrop and on the modern sea floor provide data that helps to interpret the hydrodynamic and sedimentological character of the current that formed them. Therefore, understanding the processes involved in bedform development beneath density currents will enable more accurate estimation of the properties of flows.

Statics and dynamics of a finite two-dimensional colloidal system with competing attractive critical Casimir and repulsive magnetic dipole interactions.

We continue our theoretical study of a recently proposed two-dimensional colloidal system with attractive critical Casimir and repulsive magnetic dipole forces that can be tuned easily and independently from each other via the temperature and the strength of an external magnetic field, respectively [K. Marolt, M. Zimmermann, and R. Roth, Phys. Rev. E 100, 052602 (2019)2470-004510.1103/PhysRevE.100.052602]. Using this freedom, it is possible to construct a competing interaction potential that causes microphase separation featuring spatially inhomogeneous cluster, stripe, and bubble phases in the bulk, i.e., in an infinite system without an external potential. In the present work, we demonstrate by means of density functional theory that microphase separation can also occur in finite geometries. In a square cell with a side length of 20 or 30 colloid diameters, we observe the emergence of highly structured cluster and ring phases at intermediate bulk densities in addition to almost uniform fluid phases for lower and higher bulk densities. We then employ dynamic density functional theory to determine how the system reacts when the temperature and the magnetic field are altered over time, and we show how to induce a transition from the liquid to the cluster/ring phase and also from the cluster directly to the ring phase. We find that often a slowly varying and nontrivial path in parameter space is required to reach a stable state, whereas abrupt changes are prone to lead to metastable configurations.

Action convergence of operators and graphs

AbstractWe present a new approach to graph limit theory that unifies and generalizes the two most well-developed directions, namely dense graph limits (even the more general $L^p$ limits) and Benjamini–Schramm limits (even in the stronger local-global setting). We illustrate by examples that this new framework provides a rich limit theory with natural limit objects for graphs of intermediate density. Moreover, it provides a limit theory for bounded operators (called P-operators) of the form $L^\infty (\Omega )\to L^1(\Omega )$ for probability spaces $\Omega $ . We introduce a metric to compare P-operators (for example, finite matrices) even if they act on different spaces. We prove a compactness result, which implies that, in appropriate norms, limits of uniformly bounded P-operators can again be represented by P-operators. We show that limits of operators, representing graphs, are self-adjoint, positivity-preserving P-operators called graphops. Graphons, $L^p$ graphons, and graphings (known from graph limit theory) are special examples of graphops. We describe a new point of view on random matrix theory using our operator limit framework.

Two-lane traffic flow model based on regular hexagonal cells with realistic lane changing behavior

In this paper, a two-lane cellular automata traffic flow model based on regular hexagonal cells is proposed. The realistic lane changing maneuvers with the lateral movement process, the lane changing duration, and the unsuccessful lane changing are considered by the new model. The vehicle trajectories from NGSIM dataset are used to extract the realistic lane changing maneuvers and calibrate the lane changing angle. The numerical results showed that the flow in the intermediate density range of the new model is lower than that of the traditional model. While the lane changing frequency in the same density range of the new model is higher than that of the traditional model. The lane changing duration will increase as the density grows. And the unsuccessful lane changing rate grows to large values in high density range. As to the heterogeneous traffic flow, the lane changing frequency is obviously greater than that in homogeneous condition. The trucks are more likely to make unsuccessful lane changing. And the lane changing duration of trucks is longer than that of cars in free flow region, but this is not the case in congested flow.

Global patterns for the spatial distribution of floating microfibers: Arctic Ocean as a potential accumulation zone

Despite their representativeness, most studies to date have underestimated the amount of microfibers (MFs) in the marine environment. Therefore, further research is still necessary to identify key processes governing MF distribution. Here, the interaction among surface water temperature, salinity, currents and winds explained the patterns of MF accumulation. The estimated density of floating MFs is ∼5900 ± 6800 items m−3 in the global ocean; and three patterns of accumulation were predicted by the proposed model: (i) intermediate densities in ocean gyres, Seas of Japan and of Okhotsk, Mediterranean and around the Antarctic Ocean; (ii) high densities in the Arctic Ocean; and (iii) point zones of highest densities inside the Arctic Seas. Coastal areas and upwelling systems have low accumulation potential. At the same time, zones of divergences between westerlies and trade winds, located above the tropical oceanic gyres, are predicted to accumulate MFs. In addition, it is likely that the warm branch of the thermohaline circulation has an important role in the transport of MFs towards the Arctic Ocean, emphasizing that surface water masses are important predictors. This study highlights that the Arctic Ocean is a dead end for floating MFs.

Developing Electron Microscopy Tools for Profiling Plasma Lipoproteins Using Methyl Cellulose Embedment, Machine Learning and Immunodetection of Apolipoprotein B and Apolipoprotein(a).

Plasma lipoproteins are important carriers of cholesterol and have been linked strongly to cardiovascular disease (CVD). Our study aimed to achieve fine-grained measurements of lipoprotein subpopulations such as low-density lipoprotein (LDL), lipoprotein(a) (Lp(a), or remnant lipoproteins (RLP) using electron microscopy combined with machine learning tools from microliter samples of human plasma. In the reported method, lipoproteins were absorbed onto electron microscopy (EM) support films from diluted plasma and embedded in thin films of methyl cellulose (MC) containing mixed metal stains, providing intense edge contrast. The results show that LPs have a continuous frequency distribution of sizes, extending from LDL (> 15 nm) to intermediate density lipoprotein (IDL) and very low-density lipoproteins (VLDL). Furthermore, mixed metal staining produces striking “positive” contrast of specific antibodies attached to lipoproteins providing quantitative data on apolipoprotein(a)-positive Lp(a) or apolipoprotein B (ApoB)-positive particles. To enable automatic particle characterization, we also demonstrated efficient segmentation of lipoprotein particles using deep learning software characterized by a Mask Region-based Convolutional Neural Networks (R-CNN) architecture with transfer learning. In future, EM and machine learning could be combined with microarray deposition and automated imaging for higher throughput quantitation of lipoproteins associated with CVD risk.