Relative Size Distribution Research Articles

Normal HDL–apo AI turnover and cholesterol enrichment of HDL subclasses in New Zealand rabbits with partial nephrectomy

ObjectiveThe kidney has been proposed to play a central role in apo AI catabolism, suggesting that HDL structure is determined, at least in part, by this organ. Here, we aimed at determining the effects of a renal mass reduction on HDL size distribution, lipid content, and apo AI turnover. MethodsWe characterized HDL subclasses in rabbits with a 75% reduction of functional renal mass (Nptx group), using enzymatic staining of samples separated on polyacrylamide electrophoresis gels, and also performed kinetic studies using radiolabeled HDL–apo AI in this animal model. ResultsCreatinine clearance was reduced to 35% after nephrectomy as compared to the basal values, but without increased proteinuria. A slight, but significant modification of the relative HDL size distribution was observed after nephrectomy, whereas cholesterol plasma concentrations gradually augmented from large HDL2b (+54%) to small HDL3b particles (+150%, P<0.05). Cholesteryl esters were the increased fraction; in contrast, free cholesterol phospholipids and triglycerides of HDL subclasses were not affected by nephrectomy. HDL–apo AI fractional catabolic rates were similar to controls. ConclusionReduction of functional renal mass is associated to enrichment of HDL subclasses with cholesteryl esters. Structural abnormalities were not related to a low apo AI turnover, suggesting renal contribution to HDL remodeling beyond being just a catabolic site for these lipoproteins.

Determination of Fundamental Morphological Parameters of Supported Nanoparticle Ensembles

A new model to extract important morphological parameters of noble metal nanoparticle ensembles with a broad size and shape distribution is presented. The technique is based on a rigorous simulation of the inhomogeneously broadened extinction profiles of nanoparticle ensembles. As input data, only experimentally accessible parameters, such as the amount of deposited material, the nanoparticle number density, and the relative size distribution of the nanoparticles, are used. The model can be applied to oblate nanoparticles, which exhibit a strong correlation between their shape and size, e.g., to supported nanoparticles generated, for example, by deposition of atoms and subsequent nucleation or by gas phase deposition. Both methods are standard preparation techniques to generate well-defined nanoparticle ensembles under ultra high vacuum conditions. We apply our model to gold and silver nanoparticles on sapphire and TiO2 supports and obtain a perfect agreement between the calculated and experimental data. More importantly, we could extract the functional dependence between the axial ratio and the radius of the nanoparticles within the ensemble and, therewith, the most probable axial ratio in the ensemble. In addition, the extinction spectrum of a nanoparticle ensemble irradiated with nanosecond pulsed laser light during growth has been successfully modeled. This demonstrates, that the model is able to describe shape changes of resonantly heated nanoparticles within the ensemble. By using the coverage as a free parameter, we could calculate from the extinction spectrum the average particle radius as well as the amount of desorbed atoms after irradiation with laser light. In summary, the model allows a fast, easy, but extensive morphological characterization of nanoparticle ensembles that exhibit a broad size and shape distribution.

Growth Laws and Self-Similar Growth Regimes of Coarsening Two-Dimensional Foams: Transition from Dry to Wet Limits

We study the topology and geometry of two-dimensional coarsening foam with an arbitrary liquid fraction. To interpolate between the dry limit described by von Neumann's law and the wet limit described by Marqusee's equation, the relevant bubble characteristics are the Plateau border radius and a new variable: the effective number of sides. We propose an equation for the individual bubble growth rate as the weighted sum of the growth through bubble-bubble interfaces and through bubble-Plateau border interfaces. The resulting prediction is successfully tested, without an adjustable parameter, using extensive bidimensional Potts model simulations. The simulations also show that a self-similar growth regime is observed at any liquid fraction, and they also determine how the average size growth exponent, side number distribution, and relative size distribution interpolate between the extreme limits. Applications include concentrated emulsions, grains in polycrystals, and other domains with coarsening that is driven by curvature.

Image analysis of soil failure on defective underground pipe due to cyclic water supply and drainage using X-ray CT

The ground subsidence on the underground pipe often is caused with the reduction of the effective stress and the loss of suction in the base course and then, soil drainage into the pipe. The final formation of the cavity growth in the ground was observed as the ground subsidence. Authors focused this problem and hence performed model tests with water-inflow and drainage cycle in the model ground. The mechanism of cavity generation in the model ground was observed using an X-ray Computed Tomography (CT) scanner. In those studies, water was supplied into the model grounds from the defected underground pipe model in case of the change of relative density and grain size distribution. As results, it was observed that the loosening area was generated from the defected part with water-inflow and some of the soil particles in the ground were drained into the underground pipe through the defected part. And afterward, the cavity was generated just above the defected part of the model pipe in the ground. Based on this observation, it might be said that the bulk density of soil around the defected pipe played one of key factor to generate the cavity in the ground. Moreover, the dimension of the defected part should be related to the magnification of the ground subsidence, in particular, crack width on a sewerage pipe and particle size would be the quantitative factor to evaluate the magnification of the ground subsidence.

Characterization of the University of Toronto Concentrated Aerosol Particle Exposure Facility (CAPEF)—Effects on Fine and Ultrafine Nonrefractory Aerosol Composition

Virtual impactor-based particle concentrators have been developed to enable the study of biological mechanisms and dose-response relationships of particulate matter (PM) inhalation. The Concentrated Aerosol Particle Exposure Facility (CAPEF) at the University of Toronto houses the Harvard School of Public Health designed coarse, fine, and quasi-ultrafine particle concentrators for such studies. Characterization of the concentration of the nonrefractory components of ambient particles was carried out in the winter of 2010. The fine concentrator shows higher mass concentration factors for ambient sulfate than for semi-volatile components, as measured using an Aerodyne aerosol mass spectrometer (AMS). The change in composition is based on the relative size distributions of particulate sulfate, which, compared to particulate organic and nitrate, is more dominant in larger particles more efficiently concentrated due to the physical characteristics of the virtual impactors. The ultrafine concentrator, which requires aqueous condensational growth of particles prior to concentration, shows a large enhancement in organic mass both for ambient particles and for laboratory-generated ammonium sulfate and ammonium nitrate particles added to filtered outdoor air. As suggested previously, changes in the organic mass spectrum and size distributions are consistent with addition of organic mass through reactions of water-soluble volatile organic compounds. Coagulation of particles or droplet coalescence may also account for some of the observed increase in organic mass and nitrate may be lost due to volatilization. While such effects are unlikely to affect refractory species, increased attention should be given to the effect of condensational growth on the composition of concentrated ultrafine particles. Copyright 2012 American Association for Aerosol Research

CdS-sensitized K2Ti4O9 composite for photocatalytic hydrogen evolution under visible light irradiation

CdS-sensitized K2Ti4O9 composite photo-catalysts (hereafter designated as CdS/K2Ti4O9) were prepared by a facile deposition-precipitation method. The samples were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), ultraviolet–visible diffuse reflectance spectra (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). The photo-catalytic activities for hydrogen evolution were investigated under visible light irradiation. The CdS particles, which were scattered on the surface of K2Ti4O9, had a relative uniform size distribution around approximately 50nm, and the absorption edge of K2Ti4O9 shifted to the visible light region after the deposition of CdS. The composite photo-catalyst loaded with 25wt.% CdS synthesized via precipitation method showed the highest photo-catalytic activity. The photocatalytic reaction parameters, such as the dosage of catalyst, and concentrations of sacrificial reagents, were studied and optimized. The mechanism of separation of the photo-generated electrons and holes at the CdS/K2Ti4O9 composite was also discussed.

A new insight into crustal heterogeneity beneath the 2001 Bhuj earthquake region of Northwest India and its implications for rupture initiations

The seismic characteristics of the 2001 Bhuj earthquake (Mw 7.6) has been examined from the proxy indicators, relative size distribution (3D b-value mapping) and seismic tomography using a new data set to understand the role of crustal heterogeneities in rupture initiations of the 2001 Bhuj earthquake of the Gujarat (India), one of the disastrous Indian earthquakes of the new millennium. The aftershocks sequence recorded by 22 seismograph stations of Gujarat Seismic Network (GSNet) during the period from 2006 to 2009, encompassing approximately 80km×70km rupture area had revealed clustering of aftershocks at depth of 5–35km, which is seismogenic layer responsible for the occurrence of continued aftershocks activity in the study region. The 3D b-value mapping estimated from a total of 3850 precisely located aftershocks with magnitude of completeness Mc⩾2.7 shows that a high b-value region is sandwiched within the main shock hypocenter at the depth of 20–25km and low b-value region above and below of the 2001 Bhuj main shock hypocenter. Estimates of 3-D seismic velocity (Vp; Vs) and Poisson’s ratio (б) structure beneath the region demonstrated a very close correspondence with the b-value mapping that supports the similar physicochemical processes of retaining fluids within the fractured rock matrix beneath the 2001 Bhuj mainshock hypocenter. The overall b-value is estimated close to 1.0 which reveals that seismogenesis is related to crustal heterogeneity, which, in turn also supported by low-Vs and high-б structures. The high b-value and high-б anomaly at the depth of 20–25km indicate the presence of highly fractured heterogeneous rock matrix with fluid intrusions into it at deeper depth beneath the main shock hypocenter region. Low b-value and high-Vp in the region is observed towards the north-east and north-west of the main shock that might be an indication of the existence of relatively competent rock masses with negligible volume of cracks that may have contained over-pressurized fluids without molten rocks.

Relationship between horizontal hydroacoustic stock estimates and gillnet catches of surface-oriented fish in shallow Lake Balaton (Hungary)

We examined whether gillnetting and hydroacoustics provide comparable relative fish density and fish size distribution estimates in the uppermost water layer of a shallow turbid lake and whether the inclusion of environmental and stock parameters could improve comparability of data between different gears. According to gillnetting, most fish shorter than 14 cm in total length were Alburnus alburnus, and most fish longer than 14 cm were Pelecus cultratus. Size distributions and median sizes obtained from gillnetting and acoustics differed. Pure acoustics-derived density estimates accounted for only <8.8% of the variation in the gillnet catch by number and no correlation was found in biomass indices. Most variances observed in the gillnet catch-per-unit-effort data were associated with water transparency, none of the other investigated variables had significant explanatory power. We conclude that the feasibility of establishing a powerful model describing the relationship between fish density estimates of gillnetting and acoustics is low in shallow and turbid habitats, and it might be successful only if the crucial sampling and environmental parameters affecting catch efficiency of gillnets and post-processing of acoustic data are considered. This study cautions again that gillnetting should be used carefully to analyse trends of fish abundance.

TheSrb1+1050TAllele Is Associated with Metabolic Syndrome in Children but Not with Cholesteryl Ester Plasma Concentrations of High-Density Lipoprotein Subclasses

Low cholesterol and phospholipid plasma levels of some high-density lipoprotein (HDL) subclasses have been described in children with metabolic syndrome. Scavenger receptor class B type I (SR-BI) has been proposed to be at the origin of such HDL alterations because of its key role on cholesteryl esters-HDL metabolism. However, the possible contribution of SR-BI has not been specifically explored in this kind of patients. Plasma lipid concentrations of HDL subclasses, i.e., triglycerides (TG), phosphatidylcholine (Ph), free cholesterol (FC), and total cholesterol (TC), were determined by enzymatic staining on polyacrylamide gradient gels (PAGE) in 39 pediatric patients with metabolic syndrome and 65 children as controls. Cholesteryl esters were estimated by the difference between TC and FC. Proteins of HDL subclasses were also stained for the assessment of the relative size distribution of HDL. For statistical analysis, the study population was grouped by Srb1 +1050C-->T polymorphism (rs5888) as carriers or noncarriers of the T allele, and data were corrected by metabolic syndrome status. The Srb1 +1050T allele was associated with metabolic syndrome [odds ratio (OR)=2.18 (1.12-4.22), P=0.02]. Plasma TG corresponding to HDL3a, as well as the relative proportion of this HDL subclass, were slightly higher in carriers of the T allele as compared to CC homozygous subjects. Cholesteryl esters plasma concentrations of all HDL subclasses were comparable between T allele carriers and noncarriers after correction by metabolic syndrome status. Srb1 +1050T was associated with metabolic syndrome, but T carrier subjects did not show important differences concerning HDL subclasses as compared to noncarriers.

Water Quality and Planktonic Microbial Assemblages of Isolated Wetlands in an Agricultural Landscape

Wetlands provide ecosystem services including flood protection, water quality enhancement, food chain support, carbon sequestration, and support regional biodiversity. Wetlands occur in human-altered landscapes, and the ongoing ability of these wetlands to provide ecosystem services is lacking. Additionally, the apparent lack of connection of some wetlands, termed geographically isolated, to permanent waters has resulted in little regulatory recognition. We examined the influence of intensive agriculture on water quality and planktonic microbial assemblages of intermittently inundated wetlands. We sampled 10 reference and 10 agriculturally altered wetlands in the Gulf Coastal Plain of Georgia. Water quality measures included pH, alkalinity, dissolved organic carbon, nutrients (nitrate, ammonium, and phosphate), and filterable solids (dry mass and ash-free dry mass). We measured abundance and relative size distribution of the planktonic microbial assemblage (<45 μm) using flow cytometry. Water quality in agricultural wetlands was characterized by elevated nutrients, pH, and suspended solids. Autotrophic microbial cells were largely absent from both wetland types. Heterotrophic microbial abundance was influenced by nutrients and suspended matter concentration. Agriculture caused changes in microbial assemblages forming the base of wetland food webs. Yet, these wetlands potentially support important ecological services in a highly altered landscape.

Cannibalism among size classes of larvae may be a substantial mortality component in tuna

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 433:205-219 (2011) - DOI: https://doi.org/10.3354/meps09187 Cannibalism among size classes of larvae may be a substantial mortality component in tuna P. Reglero1,*, A. Urtizberea2, A. P. Torres1, F. Alemany1, Ø. Fiksen2, 3 1Instituto Español de Oceanografía, Centre Oceanogràfic de les Balears, Moll de Ponent s/n, 07015 Palma, Spain2Department of Biology, University of Bergen, PO Box 7803, 5020 Bergen, Norway3Uni Research, PO Box 7810, 5020 Bergen, Norway *Email: patricia.reglero@ba.ieo.es ABSTRACT: Cannibalism among size classes may reduce starvation and improve survival of larval tuna in oligotrophic ocean areas, but it may also be a substantial mortality component depending onthe availability of alternative prey. Here, we combine laboratory and field data on tuna larvae with amodel of larval foraging and bioenergetics to explore the role of cannibalism in cohort developmentat different temperatures, durations of hatching period, hatching larval densities and natural mortalityrates. Prey fields (zooplankton densities and co-occurrence of different larval stages of 3 species of tuna) were established from cruises in a main tuna spawning area around the Balearic Islands (Mediterranean Sea). Results suggest that a pure zooplankton diet is frequently insufficient to sustain larval growth. Piscivory can be a major source of larval mortality among tuna species and larvae hatched early can feed on abundant larvae of smaller size and have fewer predators themselves. We show how the intensity of cannibalism depends on the temperature dependent growth rate and the resulting relative size distribution when eggs are released continuously over a period of a few weeks. The predator-prey size distribution and the relative densities of these voracious larvae may produce overcompensation in recruitment under some environmental conditions. KEY WORDS: Cannibalism · Foraging model · Intraspecific predation · Natural mortality · Pelagic larvae · Predator-prey interactions · Size spectra · Surf-riding Full text in pdf format PreviousNextCite this article as: Reglero P, Urtizberea A, Torres AP, Alemany F, Fiksen Ø (2011) Cannibalism among size classes of larvae may be a substantial mortality component in tuna. Mar Ecol Prog Ser 433:205-219. https://doi.org/10.3354/meps09187 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 433. Online publication date: July 18, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

New method for preparation of polyoxometalate-capped gold nanoparticles, and their assembly on an indium-doped tin oxide electrode

Functionalized gold nanoparticles capped with polyoxometalates were prepared by a simple photoreduction technique where phosphododecamolybdates serve as reducing reagents, photocatalysts, and as stabilizers. TEM images of the resulting gold nanoparticles show the particles to have a relative narrow size distribution. Monolayer and multilayer structures of the negatively charged capped gold nanoparticles were deposited on a poly(vinyl pyridine)-derivatized indium-doped tin oxide (ITO) electrode via the layer-by-layer technique. The surface plasmon resonance band of the gold nanoparticles displays a blue shift on the surface of the ITO electrode. This is due to the substrate-induced charge redistribution in the gold nanoparticles and a change in the electromagnetic coupling between the assembled nanoparticles. The modified electrode exhibits the characteristic electrochemical behavior of surface-confined phosphododecamolybdate and excellent electrocatalytic activity. The catalysis of the modified electrode towards the model compound iodate was systematically studied. The heterogeneous catalytic rate constant for the electrochemical reduction of iodate was determined by chronoamperometry to be ca. 1.34 × 105 mol−1·L·s−1. The amperometric method gave a linear range from 2.5 × 10−6 to 1.5 × 10−3 M and a detection limit of 1.0 × 10−6 M. We believe that the functionalized gold nanoparticles prepared by this photoreduction technique are advantageous in terms of fabrication of sensitive and stable redox electrodes.

Porous stainless steel hollow fiber membranes via dry–wet spinning

Porous stainless steel hollow fibers have been prepared via the dry–wet spinning process, based on phase inversion of a particle loaded polymer solution, followed by sintering. The morphology of the green fibers combines sponge like structures and macro voids, and is related to the dynamics of the phase inversion process. The morphology can be tuned by changing the spinning conditions and the composition of the spinning mixture. In analogy to their ceramic counterparts the morphology of the stainless steel fibers is preserved during sintering, apart from shrinkage due to densification. At a length scale comparable to the diameter of the steel particles the microstructure and related pore size distribution are more strongly affected by the sintering temperature, as compared to their ceramic counterparts. Sintering the stainless hollow fibers at temperatures > 1100 °C results in a sharp decrease in nitrogen permeance and an increase in bending strength, due to densification. The strength (∼1 GPa) and nitrogen permeance (0.1 mmol m −2 Pa −1 s −1 at 21 °C) of stainless steel fibers sintered at 1050–1100 °C are superior as compared to their ceramic counterparts. The excellent properties of the stainless steel hollow fibers make them suitable as membrane (supports) for applications involving harsh environments.

Application of percolation theory to microtomography of structured media: Percolation threshold, critical exponents, and upscaling

Percolation theory provides a tool for linking microstructure and macroscopic material properties. In this paper, percolation theory is applied to the analysis of microtomographic images for the purpose of deriving scaling laws for upscaling of properties. We have tested the acquisition of quantities such as percolation threshold, crossover length, fractal dimension, and critical exponent of correlation length from microtomography. By inflating or deflating the target phase and percolation analysis, we can get a critical model and an estimation of the percolation threshold. The crossover length is determined from the critical model by numerical simulation. The fractal dimension can be obtained either from the critical model or from the relative size distribution of clusters. Local probabilities of percolation are used to extract the critical exponent of the correlation length. For near-isotropic samples such as sandstone and bread, the approach works very well. For strongly anisotropic samples, such as highly deformed rock (mylonite) and a tree branch, the percolation threshold and fractal dimension can be assessed with accuracy. However, the uncertainty of the correlation length makes it difficult to accurately extract its critical exponents. Therefore, this aspect of percolation theory cannot be reliably used for upscaling properties of strongly anisotropic media. Other methods of upscaling have to be used for such media.

Fabrication of cuprous oxide nanoparticles by laser ablation in PVP aqueous solution

The cuprous oxide nanoparticles have been fabricated through pulsed laser ablation of copper target in PVP aqueous solution. The structure, morphology and composition of the nanoparticles have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS) and X-ray excited auger spectra (XAES). The results show that the mean size of the as-prepared in diameter is about 29 nm with a relative narrow size distribution and samples are polycrystal Cu2O nanoparticles with a shell of thin layer of amorphous CuO. Furthermore, a possible mechanism for formation of such the cuprous oxide nanoparticles is discussed. We concluded that pulsed laser ablation of copper in liquid is a feasible method for the synthesis of cuprous oxide nanoparticles.

Experimental Study of the Effects of Environmental and Fog Condensation Nuclei Parameters on the Rate of Fog Formation and Dissipation Using a New Laboratory Scale Fog Generation Facility

The IIT Kanpur Fog Chamber Facility has been conceptualized and built indigenously to study the fog formation and dissipation under various environmental conditions. The chamber has been designed such that all governing parameters can be controlled and optimized. The effects of relative humidity, temperature and size distribution, number and chemical composition of fog condensation nuclei (FCN) on the formation, stability and dissipation of fog has been studied. The visibility measurements were carried out using a He-Ne 632.8 nm monochromatic laser. It was found that aerosol number concentration, size distribution and chemical nature of FCN have significant effects on visibility reduction in fog. Direct comparisons were made for theoretical droplet growth and settling times in predicting the period for which stable fog was expected Vs the actual experimentally measured times for stable fog generated using different types of FCN. Effective radius, Reff, of fog droplet size distribution (DSD), a parameter that describes the optical properties of the droplet distribution was also calculated. It was noted that even for the same Reff (i.e. similar visibility), DSDs show notable differences depending on other conditions, implying the differences in the microphysical nature of fog. Fog dissipation results show that, with the decrease in temperature, the rate of fog dissipation decreases for all FCNs except for uncoated graphite, where no particular pattern has been observed maybe due to its less hygroscopic nature. The results from this study will help us in better understanding the optical nature of fog and designing of future fog vision devices.

Physicochemical Characterization of Sediment in Northwest Arkansas Streams

Eutrophication of surface waters is a critical concern in regions around the world facing nutrient surpluses as a result of confined animal feeding operations (CAFOs) and subsequent land application of manures. While large amounts of research exist on the transport of nutrient enriched runoff from fields to surface waters less information is available on in-stream processes controlling the transport of P in-stream. Thus, information is needed on the role of stream sediments in regulating transient phosphorus (P) to better understand the relationship between nutrient inputs and water quality. Fine-sized sediments ( 2-mm) consume and store P. From fine-sized sediment a modified P saturation ratio (PSRmod), related to the sediment’s ability to bind P and determined from Mehlich-3 extracted nutrients, has been correlated to in-stream dissolved reactive P (DRP) concentrations. The objectives of this study were to determine the relative size distribution of total- and fine-sized sediment (sand, silt clay) fractions among streams, determine the optimum sample number needed to characterize Mehlich-3 P (M3P) and PSRmod, and finally determine the applicability of PSRmod, as an indicator of stream water column DRP concentrations. Stream sediments were sampled from the 0- to 3-cm depth from stream reaches ranging from (25 – 75 m) in August, 2008 for characterization along with water samples collected from the thalweg for DRP concentration determination. Additional water column samples were collected along with fine-sized sedi- ment chemical properties in February, May, and June 2009. The distribution of sediment size classes was statistically similar, with 2- to 20- and 20- to 75-mm sized sediment dominating. Fine-sized sediment (mod, were determined to typically be sufficiently characterized by a sample scheme utilizing three samples points. Modified P saturation ratio of mod, has the potential to be used as an indicator of the ability of stream sediments to enrich stream water with P. Thus, fine-sized sediment nutrient concentrations appear to be key regulators of water column P concentrations.

Probing the Micro-Phase Separation of Thermo-Responsive Amphiphilic Polymer in Water/Ethanol Solution

The temperature-induced coil-globule transition (micro-phase separation) in water/ethanol solutions of poly(vinyl methyl ether) was studied using NMR spectroscopy, differential scanning calorimetry, optical microscopy and dynamic light scattering. NMR sequence based on spin-echo was introduced in order to determine lower critical solution temperature with high accuracy. Variation in DSC profiles and enthalpy increments depending on ethanol concentration in a water/ethanol mixture was found. Evolution of morphology pattern during heating-cooling cycle was observed using optical microscopy. At lower PVME concentration the globule size distribution was determined using digital image processing. Relative number and relative mass size distributions of globules in a dilute sample were measured by differential scanning calorimetry and subsequently compared with those obtained by optical microscopy.

Lipid plasma concentrations of HDL subclasses determined by enzymatic staining on polyacrylamide electrophoresis gels in children with metabolic syndrome

Background The antiatherogenic role of different HDL subclasses is still controversial. HDL particles of the same size can have different lipid contents in some physiopathological situations. However, little is known about the plasma lipid levels of HDL subclasses when they are separated by their hydrodynamic diameter. Methods Triglycerides (Tg), phosphatidylcholine (Ph), and cholesterol (C) plasma concentrations of HDL subclasses, were determined by enzymatic staining on polyacrylamide gradient gel (PAGE) in 50 pediatric patients with metabolic syndrome (MS), and 50 control children paired by age and gender. Proteins of HDL subclasses were also stained for the assessment of the relative size distribution of HDL. Results Relative HDL size distribution was shifted to small particles in MS pediatric patients when determined per protein. In contrast, cholesterol plasma concentrations corresponding to the HDL2b, 2a, 3a, and 3b subclasses were decreased; triglycerides of HDL3b and 3c, as well as plasma phospholipids from HDL3c, were elevated in MS patients as compared to controls. The C-to-Ph ratio, considered as indicative of HDL composition, was similar among the 5 HDL subclasses in control subjects, whereas this ratio gradually decreased from large HDL2b to small HDL3c in the MS group. Cholesterol plasma concentrations of HDL subclasses correlated with the components of the MS. Conclusions Lipids of HDL subclasses provide more and accurate information than the relative HDL size distribution determined by protein staining, and may contribute to understand better HDL metabolism and the coronary risk associated to these lipoproteins.

The influence of tectonic regimes on the earthquake size distribution: A case study for Italy

We explore the hypothesis that the relative size distribution of earthquakes, or b‐value, systematically depends on the style‐of‐faulting of seismotectonic zones. Because the b‐value has been shown to be inversely proportional to stress, we expect to find b(thrust) &lt; b(strike‐slip) &lt; b(normal). We test this expectation for the case of Italy. We first of all build a seismotectonic zonation model, consisting of 10 distinct tectonic zones. The faulting style of each zone is then characterized by the summed moment tensor of first‐motion and full‐waveform based focal mechanism. We calculate the b‐value for each zone: the lowest values are obtained for reverse zones (0.75–0.81), highest for the normal (1.09), followed by the strike‐slips (0.9–0.92). Our results suggest that b‐values, which are a critical parameter in all seismic hazard assessments, should be set according to the local faulting regimes. In addition, seismotectonic zonation models should take b‐value variations as one input.