Histogram Of Sizes Research Articles

A Novel Method for Detecting Protein Aggregates Using Plasmonic Sensing

AbstractBackgroundAmyloid‐beta (Aβ) protein aggregates have been implicated in the pathology of Alzheimer’s disease (AD). These aggregates are difficult to characterise due to their small size, requiring very sensitive techniques. Gold Nanoparticles (AuNPs) form plasmonic cavities when in close proximity to a gold surface. The cavity both enhances and scatters incident light, with a resonant wavelength strongly dependent on the size of the cavity. These plasmonic cavities were used to detect and size Aβ aggregates at ultra‐low concentration using darkfield spectroscopy.MethodsAuNPs were coated with the Aβ specific 6E10 capture antibody, incubated with a synthetic aggregate sample, and centrifuged to isolate the AuNPs. They were then placed on a gold surface, and darkfield scattering spectra were obtained. The peak scattering wavelengths for each AuNP were used to produce a histogram of gap sizes, and thus the size distribution of detected protein aggregates.ResultsSignificant differences were seen in resonant peak position between monomeric samples of Aβ and 24 hour aggregated samples. This allows for easy identification of protein monomer vs fibrillar aggregates. In the case of aggregates, some peaks in the darkfield scattering spectra also appeared strongly polarised, suggesting dimerisation of the AuNPs. This was not present for the case of monomeric sample.ConclusionsWith this novel technique it was possible to clearly distinguish between samples of Aβ monomer and aggregates. This approach can likely be expanded to find the range and proportion of aggregate sizes in serum samples to detect the onset of AD. The AuNP dimerisation when Aβ aggregates are present is also interesting, and may serve as further verification of the size or shape of these aggregates.

An Algorithm to Determine the Truncated Weibull Parameters for Distribution of Throats and Pores in Random Network Models

In random network models, sizes for pores and throats are distributed according to a truncated Weibull distribution. As a result, parameters defining the shape of the distribution are critical for the characteristic of the network. In this paper, an algorithm to distribute pores and throats in random network was established to more representatively describe the topology of porous media. First, relations between Weibull parameters and the distribution of dimensionless throat sizes were studied and a series of standard curves were obtained. Then, by analyzing the capillary pressure curve of the core sample, frequency distribution histogram of throat sizes was obtained. All the sizes were transformed to dimensionless numbers ranged from 0 to 1. Curves of the core were compared to the standard curves, and truncated Weibull parameters could be determined according an inverse algorithm. Finally, aspect ratio and average length of throats were adjusted to simultaneously fit the porosity and the capillary pressure curves and the whole network was established. The predicted relative permeability curves were in good agreement with the experimental data of cores, indicating the validity of the algorithm.

Controllable formation of plasmonic gold nanoparticles by pulsed laser–induced etching

This work discusses the preparation and formation of macro porous silicon (PSi) with silicon nano pillars; synthesized via laser–induced etching. The role of laser pulse duty cycle (10–100%) was investigated for silicon nano pillars samples creation using laser diode; characterized by its short wavelength (405 nm) and high laser intensity (500 mW/cm2). Morphological and spectroscopic aspects of the Si nanocrystallite sizes and plasmonic Au–NP, surface topography, roughness and thickness of the created layer were investigated by the scanning probe microscopy, photoluminescence measurements, the analysis of (FESEM) images and (XRD) patterns. The results revealed well-regulated Si nano pillars layers after adjusting the laser duty cycle under the same laser intensity and etching time. The histogram of Si nano pillars sizes, surface roughness and altitude of nano pillars within macro PSi created at 20% laser duty cycle showed specific characteristics; due to the minimal heat accumulation within the pillars and limited probability of damaging the pillars’ morphological aspects. The Si nano pillars were employed to synthesize and control the plasmonic features of Au-NPs. The histogram of hotspot regions and plasmonic Au-NPs sizes and their specific surface areas and grain size showed well-controlled structures after adjusting the laser pulse duty cycle.

Influence of Combustion Temperature of the Chelating-Fuel Agent on the Morphology of ZnCr2O4 nanoparticles

Zinc chromite nanoparticles are a material with a wide range of properties from catalytic to semiconductor, which find practical application in the fields of catalysis, electronics, sensorics, medicine, etc. The main properties of nanoparticles directly depend from structure, size and shape of each particles. In turn, one of the key factors for varying the properties of the nanomaterials is changes of nanoparticles morphology that can be carried out by thermal action. In this paper, the influence of the combustion temperature during the sol-gel syntheses of chelating-fuel agents on the size, size distribution and structural formation of zinc chromite nanoparticles was studied. Tartaric acid with combustion temperature 505 °C and hexamethylenetetramine with combustion temperature 1100 °C were used as chelating-fuel agents. By transmission electron microscopy the morphology of samples was studied. It was found that tartaric acid allow the formation of ZnCr2O4 nanoparticles with nearly the same morphology and size of about 30-55 nm with exception for a few bigger particles. Found shapes of the obtained nanoparticles by tartaric acid are close to cubic and cubic truncated. From the histogram of sizes it was found that the dominant formed number of nanoparticles is obtained with a size of about 50 nm. In return, hexamethylenetetramine as chelating-fuel agent provokes the formation of nanoparticles with about 50-100 nm in size and none uniform morphology. By X-ray diffraction analysis (XRD) and Fourier transform infrared analysis (FT-IR) were confirmed that all synthesized nanoparticles were obtained with a pure spinel structure. In detail, it was not found the rest of organic compound after burning of the combustion agents and it was not detected any other crystalline compound (ZnO or Cr2O3) during the FT-IR and XRD analyses. Thus, summarizing that tartaric acid as a chelating-fuel agent is a more promising compound in terms of ZnCr2O4 nanoparticles synthesis with approximately uniform morphology. In particular, the optimal conditions for the synthesis of ZnCr2O4 nanoparticles are reported.

Estimating extremely low probability of stochastic defect in extreme ultraviolet lithography from critical dimension distribution measurement

Projection lithography using extreme ultraviolet (EUV) light at 13.5-nm wavelength will be applied to the production of integrated circuits below 7-nm design rules. In pursuit of further miniaturization, however, stochastic pattern defect problems have arisen, and monitoring such defect generation probabilities in extremely low range (<10 − 10) is indispensable. We discuss a method for predicting stochastic defect probabilities from a histogram of feature sizes for patterns several orders of magnitude fewer than the number of features to inspect. Based on our previously introduced probabilistic model of stochastic pattern defect, the defect probability is expressed as the product sum of the probability for edge position and the probability that film defect covers the area between edges, and we describe the latter as a function of edge position. The defect probabilities in the order between 10 − 7 and 10 − 5 were predicted from 105 measurement data for real EUV-exposed wafers, suggesting the effectiveness of the model and its potential for defect inspection.

Tailored laser pulse method to manipulate filler wire melt metallurgy from thermal cycles

A robust method is introduced to simulate and study the filler wire metallurgy for controlled cooling conditions after melting, enabling efficient mapping with prompt analysis of trends. Proposed is a reduced, though representative, process with more controllable conditions. Short lengths of filler wires are preplaced in a cavity, drilled into a base metal sheet. Irradiation by a pulsed laser beam melts the wire to generate a sample nugget. Pulse shaping influences the cooling rate, granting the ability to tailor weldament microstructures. The method is demonstrated for S1100QL steel and undermatched filler wire, to obtain high toughness for processes like laser-arc hybrid welding, where a representative thermal cycle is needed. For high toughness, a controlled amount of acicular ferrite and, in turn, nonmetallic inclusions is desirable. This “snapshot” method has revealed a characteristic histogram of inclusion sizes, for different pulse shapes. Additional information on the thermal cycle can be acquired by employing thermocouples, a pyrometer, or advanced methods like high speed imaging or modeling. The method offers a wide spectrum of variants and applications.

Dynamic windowing mechanism to combine sentiment and N-gram analysis in detecting events from social media

Social sensing is a new paradigm that inherits the main ideas of sensor networks and considers the users as new sensor types. For instance, by the time the users find out that an event has happened, they start to share the related posts and express their feelings through the social networks. Consequently, these networks are becoming a powerful news media in a wide range of topics. Existing event detection methods mostly focus on either the keyword burst or sentiment of posts, and ignore some natural aspects of social networks such as the dynamic rate of arriving posts. In this paper, we devised Dynamic Social Event Detection approach that exploits a new dynamic windowing method. Besides, we add a mechanism to combine the sentiment of posts with the keywords burst in the dynamic windows. The combination of sentiment analysis and the frequently used keywords enhances our approach to detect events with a different level of user engagement. To analyze the behavior of the devised approach, we use a wide range of metrics including histogram of window sizes, sentiment oscillations of posts, topic recall, keyword precision, and keyword recall on two benchmarked datasets. One of the significant outcomes of the devised method is the topic recall of 100% for FA Cup dataset.

Regionalization of multi-categorical landscapes using machine vision methods

We introduce a novel method for regionalization of multi-categorical landscape or land cover pattern based on the principle of machine vision rather than clustering of landscape metrics. Maps of land use/land cover (LULC), such as, for example, the NLCD 2006, show spatially varying pattern of LULC categories. Using an LULC map as an input our method discovers and maps different landscape types (LTs), each dominated by a characteristic LULC pattern that reflects varied influence of natural and anthropogenic factors. At the core of the method are the concepts of landscape signature and landscape dissimilarity adapted from the field of machine vision. A two-dimensional histogram of LULC categories and clump sizes is used as a landscape signature and the Jensen-Shannon measure is used as landscape dissimilarity. We have also adapted the machine vision technique of object-bases image analysis, consisting of segmentation and clustering, to find the set of LTs regions. Such technique maximizes spatial contiguity of the regions while also providing necessary level of generalization. The method is applied to the study area located in the northern part of the U.S. state of Georgia using the NLCD 2006 data. Local landscape is defined over a square, 3 km × 3 km areal units; there are 8475 such units in the study area. Several different computational protocols for regionalization of these units are evaluated with the best protocol resulting in a discovery and delineation of fifteen LTs. The LTs are summarized from descriptive and quantitative perspective, their landscapes signatures are shown, and an example of each landscape is given. Delineated LTs agree well with perceptual patterns seen in the NLCD map. Non-urban LTs are arranged roughly in stripes running from SW to NE perpendicular to the regional gradient of elevation. Full resolution maps, the data, and our regionalization computer code are available at http://sil.uc.edu/downloads.html.

Synaptic Ribbons Influence the Size and Frequency of Miniature-like Evoked Postsynaptic Currents

Nonspiking cells of several sensory systems respond to stimuli with graded changes in neurotransmitter release and possess specialized synaptic ribbons. Here, we show that manipulations to synaptic ribbons caused dramatic effects on mEPSC-like (mlEPSC) amplitude and frequency. Damage to rod-bipolar cell ribbons using fluorophore-assisted light inactivation resulted in the immediate reduction of mlEPSC amplitude and frequency, whereas the first evoked response after damage remained largely intact. The reduction in amplitude could not be recovered by increasing release frequency after ribbon damage. In parallel experiments, we looked at mlEPSCs from cones of hibernating ground squirrels, which exhibit dramatically smaller ribbons than awake animals. Fewer and smaller mlEPSCs were observed postsynaptic to cones from hibernating animals, although depolarized cones were able to generate larger mlEPSCs. Our results indicate that ribbon size may influence mlEPSC frequency and support a role for ribbons in coordinating multivesicular release.

Multiple, Dynamic, Packing Strategies of Ryanodine Receptors in Ventricle

Ryanodine receptors (RYR) interact with each other through subdomain 6, the clamp region. This interaction is thought to hold the monomers in a checkerboard orientation and to be the source of allosteric interaction. However, analysis of 2D electron micrographs acquired from adult rat ventricular myocytes indicated this is not the only packing strategy. Specifically, a histogram of RYR2 sizes showed the expected peak at 29 nm, and additional peaks at multiples of 29 nm. This could only be explained if the monomers were arranged side-by-side, rather than in a checkerboard. We confirmed this using electron tomography, obtaining direct en face views of RYR packing. We observed two strategies within a given couplon; the expected checkerboard and a side-by-side arrangement. Others, using purified RYR type 1, have identified a Mg2+ -sensitive packing; a checkerboard in 0 mM Mg2+, and in 4 mM Mg2+ a side-by-side orientation that precludes allosteric interaction1. To determine whether the RYR2 packing in vivo was sensitive to Mg2+, we used saponin-permeabilized myocytes, clamping the Mg2+ concentration between 0.5 mM (low end of physiological range) and 4.0 mM (ischemia) and observed that the packing changed from checkerboard to side-by-side as the [Mg2+] increased. The packing at normal physiological Mg2+ (0.5 - 1.5 mM) reflects both strategies. Furthermore, the RYR2 monomers could be rapidly rearranged following a change in [Mg2+], completing the transition from checkerboard to side-by-side orientation within five minutes. Consistent with published results, increasing [Mg2+] decreased Ca2+ spark frequency in saponin-permeabilized myocytes2. These results imply that RYR2 monomers within a couplon have multiple packing strategies and Ca2+ sensitivities, both of which can be rapidly altered by local factors.1. Yin, C. et al, J Mol Biol, 349;538-546, 20052. Gusev, K, Niggli, E, J Gen Physiol, 6;721-730, 2008

Size distribution and waiting times for the avalanches of the Cell Network Model of Fracture

The Cell Network Model is a fracture model recently introduced that resembles the microscopical structure and drying process of the parenchymatous tissue of the Bamboo Guadua angustifolia. The model exhibits a power-law distribution of avalanche sizes, with exponent −3.0 when the breaking thresholds are randomly distributed with uniform probability density. Hereby we show that the same exponent also holds when the breaking thresholds obey a broad set of Weibull distributions, and that the humidity decrements between successive avalanches (the equivalent to waiting times for this model) follow in all cases an exponential distribution. Moreover, the fraction of remaining junctures shows an exponential decay in time. In addition, introducing partial breakings and cumulative damages induces a crossover behavior between two power-laws in the histogram of avalanche sizes. This results support the idea that the Cell Network Model may be in the same universality class as the Random Fuse Model.

Mean field convergence of a model of multiple TCP connections through a buffer implementing RED

RED (Random Early Detection) has been suggested when multiple TCP sessions are multiplexed through a bottleneck buffer. The idea is to detect congestion before the buffer overflows by dropping or marking packets with a probability that increases with the queue length. The objectives are reduced packet loss, higher throughput, reduced delay and reduced delay variation achieved through an equitable distribution of packet loss and reduced synchronization. Baccelli, McDonald and Reynier [Performance Evaluation 11 (2002) 77–97] have proposed a fluid model for multiple TCP connections in the congestion avoidance regime multiplexed through a bottleneck buffer implementing RED. The window sizes of each TCP session evolve like independent dynamical systems coupled by the queue length at the buffer. The key idea in [Performance Evaluation 11 (2002) 77–97] is to consider the histogram of window sizes as a random measure coupled with the queue. Here we prove the conjecture made in [Performance Evaluation 11 (2002) 77–97] that, as the number of connections tends to infinity, this system converges to a deterministic mean-field limit comprising the window size density coupled with a deterministic queue.

Routes to spatiotemporal chaos in the rheology of nematogenic fluids

With a view to understanding the "rheochaos" observed in recent experiments in a variety of orientable fluids, we study numerically the equations of motion of the spatiotemporal evolution of the traceless symmetric order parameter of a sheared nematogenic fluid. In particular we establish, by decisive numerical tests, that the irregular oscillatory behavior seen in a region of parameter space where the nematic is not stably flow-aligning is in fact spatiotemporal chaos. We outline the dynamical phase diagram of the model and study the route to the chaotic state. We find that spatiotemporal chaos in this system sets in via a regime of spatiotemporal intermittency, with a power-law distribution of the widths of laminar regions, as in H. Chaté and P. Manneville, Phys. Rev. Lett. 58, 112 (1987). Further, the evolution of the histogram of band sizes shows a growing length scale as one moves from the chaotic towards the flow-aligned phase. Finally we suggest possible experiments in which one can observe the intriguing behaviors discussed here.

Observations on the morphology of axons and somata of slowly conducting dorsal root ganglion cells in the cat

In anaesthetized cats, the somata of cervical dorsal root ganglion (DRG) cells were impaled with glass micropipettes containing horseradish peroxidase. Slowly conducting afferent units were first classified by the conduction velocity of the peripheral axon (group IV: < 2.5 m/s, group III: 2.5 – 30 m/s) and then injected iontophoretically with horseradish peroxidase in order to visualize the perikaryon and the axons close to the ganglion. All units classified as group IV had non-myelinated peripheral and central axons. DRG cells classified as group III were morphologically heterogeneous. Units conducting in the lower group III range had non-myelinated axons on both sides of the bifurcation; in those having an intermediate conduction velocity only the peripheral axon was myelinated, and in the fastest conducting group III units both the peripheral and central axons were myelinated. One out of the 36 stained cells gave rise to 3 processes, namely 1 central axon and 2 peripheral branches. The latter ones left the ganglion at its distal pole. Within the ganglion a significant tapering of the peripheral axon of group IV afferent units was observed. In the frequency distribution histogram of cell sizes, the cross-sectional areas of group IV somata were not restricted to the lower extreme of the distribution, but showed a great overlap with the somata of group III and even group II and I units.

Experiments on the characterization of metamorphic textures from a micrograph of an amphibolite

SUMMARYPicture processing using generalized instrumentation with specially developed software, and image analysis by means of a Quantimet 720 image analyser with a linear correlator, were employed in the study of rock textures. The boundaries of all individual grains from a portion of a thin section of a rock were distinguished and hand‐drafted for digitization and analysis. From the grey level image of boundaries of the profiles of the grains, obtained by hexagonal scanning of line drawings, binary images were produced for each phase and used for textural measurements. Ink drawings extracted from the boundary pattern were also used for the image analyser experiments.In picture processing experiments, programmed structuring elements of different shapes and two‐dimensional autocorrelation functions were used to characterize morphology and spatial distribution of the different phases. Transformations of binary images were programmed at the bit level to reduce storage requirements and computing time. In Quantimet 720 experiments, linear erosion and histogram of sizes were used for computing the mean dimensions of the grains. Periodical arrangements were studied by means of the covariance function.This contribution uses simple texture measures derived from mathematical morphology and picture processing methods, in order to assess the feasibility of two different technical approaches in the analysis of the same material. The extraction of image information from the material analysed, which was not attempted before, is cumbersome and technically complex. This difficulty is partly responsible of why little is known on the quantitative characterization of metamorphic textures from thin sections.

Changes in thylakoid structure associated with the differentiation of heterocysts in the cyanobacterium, Anabaena cylindrica

The thylakoids of vegetative cells of the filamentous cyanobacterium, Anabaena cylindrica, are capable of oxygen-evolving photosynthesis and contain both Photosystems I and II (PSI and PSII). The heterocysts, cells specialized for nitrogen fixation, do not produce oxygen and lack Photosystem II activity, the major accessory pigments, and perhaps the chlorophyll a associated with PSII. Freeze-fracture replicas of vegetative cells and of heterocysts reveal differences in the structure of the thylakoids. A histogram of particle sizes on the expolasmic fracture face (E-face, EF) of vegetative cell thylakoids has two major peaks, at 75 and 100 Å. The corresponding histogram for heterocyst thylakoids lacks the 100 Å size class, but has a very large peak at about 55 Å with a shoulder at 75 Å. Histograms of protoplasmic fracture face (P-face, PF) particle diameters show single broad peaks, the mean diameter being 71 Å for vegetative cells and 64 Å for heterocysts. The thylakoids of both cell types have about 5600 particles/μm 2 on the P-face. On the E-face, the density drops from 939 particles/μm 2 on vegetative cell thylakoids to 715 particles/μm 2 on heterocyst thylakoids. The data suggest that the 100 Å E-face particle of vegetative cell thylakoids is a PSII complex. The 55 Å EF particle of heterocysts may be part of the nitrogenase complex or a remnant of the PSII complex. The role of the 75 Å EF particle is unknown. Other functions localized on cyanobacterial thylakoids, such as respiration and hydrogenase activity, must be considered when interpreting the structure of these complex thylakoids.

Detection of long-range sequence order in Drosophila melanogaster satellite DNA IV by a photochemical crosslinking reaction and denaturation microscopy

Satellite DNA IV of Drosophila melanogaster has been isolated in an actinomycin/CsCl gradient and allowed to react with tritium-labeled 4,5′,8-trimethylpsoralen (trioxsalen) in the presence of long wavelength ultraviolet light. Saturation experiments showed a limiting covalent binding of approximately one trioxsalen molecule per three base-pairs for the photochemical reaction. The buoyant density change of satellite IV (ρ = 1·705 g/cm3) after photoreaction was found to be −0·182 (g/cm3)/(trioxsalen/base-pair). To visualize directly the interstrand crosslinks, the photochemically reacted satellite DNA was denatured and spread for electron microscopy. From 85% to 90% of the molecules examined have an appearance of long stretches of tandem loops with few observable double-stranded regions. The histogram of loop sizes in these denatured molecules shows a regular distribution of crosslinkable sites along satellite DNA IV with an interval of approximately 250 base-pairs, suggesting that a long-range periodicity of sequences exists in this satellite DNA. After extensive crosslinking, the observed loops still have sizes that are multiples of 250 base-pairs. These results are discussed in terms of the sequence of satellite DNA IV, the characteristics of the photochemical reaction, and theories of evolution of satellite DNA sequences.

Coalescence par chocs intergranulaires dans les couches minces (cas de l'or sur (100) KCl)

A discontinuous gold layer has been produced in UHV on a cleaved (100) KCl surface at 20 °C and afterwards annealed in the range between 200° and 300 °C. The histograms of the size and orientation of the crystallites are investigated and a theory of coalescene by intercrystallite collisions is developed. Differential equations describing coalescence by collisions are presented and solved numerically. From the initial histogram of sizes the theory yields an evolution of the distribution after annealing which agrees with the experimental results. The analysis of the experiments discussed shows that only very few collisions lead to a coalescence. The orientation between two crystallites may be important for the appearance of coalescence.