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Context: Within the western and central North Pacific Ocean stock of striped marlin (Kajikia audax), reproductive information is lacking for the central North Pacific. Aims: To derive estimates of sex-specific functional maturity ogives, eye-to-fork length at 50% maturity, reproductive phase composition, spawning season and sex ratios by sampling the Hawaii-based pelagic longline fishery. Methods: Gonad histology was exclusively used to confirm sex and estimate all reproductive life history traits. Key results: Females spawn in May–July; males are capable of spawning year-round. Best length at 50% maturity estimates were based on datasets restricted to the female spawning season (eye–fork length for females 152.2 cm and for males 109.0 cm). Length distributions and sex ratios are seasonally dynamic around Hawaii and differ from those in other Pacific regions. Conclusions: Length-at-maturity estimates for the central North Pacific are lower than all sex-specific estimates reported from other Pacific regions. Implications: The new maturity estimates will improve determinations of stock resilience and productivity in upcoming international assessments. Striped marlin spawning in the central North Pacific was previously little studied. Our investigation has shown that both females and males mature at smaller sizes than in all other Pacific regions surveyed. These results have direct application for current efforts to evaluate the health and resilience of the population in the western and central North Pacific, which is currently considered to be commercially overfished and subject to continued overfishing. [ABSTRACT FROM AUTHOR]

Fish schools are available at fish catching area for any reason. Some researchers showed that prey activity is one reason of the availability of fish school at lift net fishing area. Feeding time of each species is different. During lift net fishing, fishermen will haul the net when there are many fish at fishing location. Therefore, the author was interested to investigate differential hauling time. The objective of this research was to investigate weight, species, size distribution and homogeneity of catch at differential hauling time. The experimental fishing method was used to collect the data at this experiment. Data collection was carried out for 10 fishing operation while a fishing trip was threat as one repetition. Kruskal-Wallis test was used to analyze difference of catch weight, length distribution of dominant catch at differential hauling time. Homogeneity of catch at differential hauling time was analyzed by Shannon Wiener Index. Result of Kruskal-Wallis test indicated that weight of catch was significantly different at different hauling period with Pvalue of 0,041 (P<0,05). Furthermore, Kruskal Wallis test on length of dominant catch indicated that length of scads and squid was significantly different at different hauling time. Result of Index Shannon Wiener indicated that the highest catch homogeneity was occurred at midnight hauling time, with value of 1,956. [ABSTRACT FROM AUTHOR]

The growth and evolution of one-dimensional nanostructures on metal stepped surfaces were studied using the kinetic Monte Carlo method. The distribution of nanochain lengths was shown to change differently when the substrate was heated and cooled. Regularities are described that connect the nature of changes in the length distribution and the relative values of diffusion barriers for adatoms on the surface, which will make it possible to predict the length distribution of the resulting one-dimensional nanostructures. [ABSTRACT FROM AUTHOR]

The paper deals with the code length distributions for which the proportion of the codewords of a given length to all words of this length is a suitable power of 1/2. We derive a lower bound and an upper bound for the number of prefix codes with the above property. We also investigate the ratio of prefix codes to all uniquely decodable codes, which relates to the more general results of Woryna (Discret Math 340(2):51–57, 2017; Discret Appl Math 244:205–213, 2018). [ABSTRACT FROM AUTHOR]

Striped catfish Pangasianodon hypopthalmus (Sauvage, 1878) is a flagship catfish species of the Mekong River region, a commercially valuable food fish that is important in freshwater fisheries, and a popular aquaculture species in many Asian countries. The species was assessed as "Endangered" by the International Union for Conservation of Nature (IUCN) due to range contraction and declining abundance, though the status of the species' wild population in Cambodia, a critical habitat for the species, is not well understood. Here, we assess the population status of the striped catfish in Cambodia using multiple sources, including time-series catch data and length frequency distribution data from a commercial fishery (stationary trawl bagnet or dai) operated in the Tonle Sap River from 1998/99 to 2017/18 and larval drift data monitored in the Mekong River in Phnom Penh from 2004 to 2018. We found that there was a significant decline (R2 = 0.54, p = 0.0002) in the catch (metric tonnes) of the striped catfish from the commercial dai fishery over the last two decades. Similarly, length-based indicator analysis indicates that striped catfish mean length and abundance have both declined over the study period, raising concerns about the sustainability of river catfish fisheries. Moreover, long-term larval drift monitoring in Mekong River shows that there was a marginally significant decline in the quantity of striped catfish larvae/juvenile drifting downstream to the lower floodplain over the last decade. Changes in flood index (extent and duration of flood) in the Tonle Sap floodplain affected by the Mekong's flow are likely key factors driving the decline of the wild populations of the striped catfish. Both larval fish abundance and floodplain fish harvests have a significant positive relationship with Mekong flow and flood extent. Indiscriminate fishing exacerbates pressures on striped catfish stocks. Therefore, actions such as maintaining natural seasonal flows (flood timing, extent, and duration) to the Tonle Sap floodplain and protecting migratory fish stocks from overharvest and habitat fragmentation are essential to the persistence of stocks of striped catfish and other large-bodied migratory fishes that utilize both the Cambodian Mekong and Tonle Sap floodplains. [ABSTRACT FROM AUTHOR]

Fracture studies commonly lack data for the length range between 10 m to 1 km. For this reason, scaling laws are required to extrapolate fracture properties, for example in discrete fracture network models. This study focused on analysis and correlation of topology, orientation and length distribution of multiscale fracture datasets to assess their scalability. The used datasets comprise UAV-derived photogrammetric models from natural outcrops and lineaments mapped using airborne LiDAR, bathymetry and aerogeophysical data, in several contrasting scales and resolutions. This study highlights challenges in acquiring uncensored and coherent brittle structural datasets from source data characterized by a large span of resolutions between the remote sensing datasets and models of the fractured outcrop. In specific, collected data was found to be potentially biased and affected by uncertainties related to both the censoring by sedimentary cover and the scale of observation. Our results revealed differences between lineament and outcrop fracture orientations, as well as difficulties in assessing topological parameters from lineament datasets. The 1:200000 resolution was found best suited to the mapping of lineament length and resulted in a length distribution power law exponent of -1.92. For outcrop fractures that are less than 2 m long, the lognormal length distribution provided the only good fit to our data, while the longer outcrop fractures fitted relatively well with a power law exponent of -2.26.

Fracture studies commonly lack data for the length range between 10 m to 1 km. For this reason, scaling laws are required to extrapolate fracture properties, for example in discrete fracture network models. This study focused on analysis and correlation of topology, orientation and length distribution of multiscale fracture datasets to assess their scalability. The used datasets comprise UAV-derived photogrammetric models from natural outcrops and lineaments mapped using airborne LiDAR, bathymetry and aerogeophysical data, in several contrasting scales and resolutions. This study highlights challenges in acquiring uncensored and coherent brittle structural datasets from source data characterized by a large span of resolutions between the remote sensing datasets and models of the fractured outcrop. In specific, collected data was found to be potentially biased and affected by uncertainties related to both the censoring by sedimentary cover and the scale of observation. Our results revealed differences between lineament and outcrop fracture orientations, as well as difficulties in assessing topological parameters from lineament datasets. The 1:200 000 resolution was found best suited to the mapping of lineament length and resulted in a length distribution power law exponent of -1.92. For outcrop fractures that are less than 2 m long, the lognormal length distribution provided the only good fit to our data, while the longer outcrop fractures fitted relatively well with a power law exponent of -2.26. [ABSTRACT FROM AUTHOR]

The contractile apparatus of smooth muscle is malleable to accommodate stress and strain exerted on the muscle cell and to maintain optimal contractility. Structural lability of smooth muscle myosin filaments is believed to play an important role in the cell's malleability. However, the mechanism and regulation of myosin filament formation is still poorly understood. In the present in vitro study, using a static light scattering method, length distributions were obtained from suspensions of short myosin filaments (SFs) formed by rapid dilution or long ones (LFs) formed by slow dialysis. The distributions indicated the presence of dynamic equilibriums between soluble myosin and the SFs; i.e.: trimers, hexamers and mini filaments, covering the range up to 0.75 µm. The LFs were more stable, exhibiting favorable sizes at about 1.25, 2.4 and 4.5 µm. More distinct distributions were obtained from filaments adsorbed to a glass surface, by evanescent wave scattering and local electric field enhancement. Addition of telokin (TL) to the suspensions of unphosphorylated SFs resulted in widening of the soluble range, while in the case of the LFs this shift was larger, and accompanied by reduced contribution of the soluble myosin species. Such changes were largely absent in the case of phosphorylated myosin. In contrast, the presence of Mg·ATP resulted in elongation of the filaments and clear separation of filaments from soluble myosin species. Thus, TL and Mg·ATP appeared to modify the distribution of myosin filament lengths, i.e., increasing the lengths in preparing for phosphorylation, or reducing it to aid dephosphorylation. [ABSTRACT FROM AUTHOR]

Striped catfish Pangasianodon hypopthalmus (Sauvage, 1878) is a flagship catfish species of the Mekong River region, a commercially valuable food fish that is important in freshwater fisheries, and a popular aquaculture species in many Asian countries. The species was assessed as “Endangered” by the International Union for Conservation of Nature (IUCN) due to range contraction and declining abundance, though the status of the species’ wild population in Cambodia, a critical habitat for the species, is not well understood. Here, we assess the population status of the striped catfish in Cambodia using multiple sources, including time-series catch data and length frequency distribution data from a commercial fishery (stationary trawl bagnet or dai) operated in the Tonle Sap River from 1998/99 to 2017/18 and larval drift data monitored in the Mekong River in Phnom Penh from 2004 to 2018. We found that there was a significant decline (R2 = 0.54, p = 0.0002) in the catch (metric tonnes) of the striped catfish from the commercial dai fishery over the last two decades. Similarly, length-based indicator analysis indicates that striped catfish mean length and abundance have both declined over the study period, raising concerns about the sustainability of river catfish fisheries. Moreover, long-term larval drift monitoring in Mekong River shows that there was a marginally significant decline in the quantity of striped catfish larvae/juvenile drifting downstream to the lower floodplain over the last decade. Changes in flood index (extent and duration of flood) in the Tonle Sap floodplain affected by the Mekong’s flow are likely key factors driving the decline of the wild populations of the striped catfish. Both larval fish abundance and floodplain fish harvests have a significant positive relationship with Mekong flow and flood extent. Indiscriminate fishing exacerbates pressures on striped catfish stocks. Therefore, actions such as maintaining natural seasonal flows (flood timing, extent, and duration) to the Tonle Sap floodplain and protecting migratory fish stocks from overharvest and habitat fragmentation are essential to the persistence of stocks of striped catfish and other large-bodied migratory fishes that utilize both the Cambodian Mekong and Tonle Sap floodplains.

In this work, we perform a comparative analysis of length distributions of proteins belonging to two virus families, namely Flaviviridae and Coronaviridae. Both families of viruses are highly contagious and represent severe threats to global health systems. To perform the comparative analysis, we retrieved data from the databases Virus Pathogen Database and Analysis Resource (ViPR) and National Center for Biotechnology Information (NCBI). In our investigation, we have considered four distinct Cumulative Distribution Functions (CDFs) of protein length: q -Exponential-CDF and q -Gaussian-CDF, q -Weibull-CDF, and κ -Maxwellian-CDF. Our results show that q -Weibull-CDF is the least appropriate for length distributions among the four CDFs. Also, the q -Exponential, q -Gaussian, and κ -Maxwellian distribution functions fit the cumulative distributions of viral protein lengths with remarkable agreement. Furthermore, our findings suggest that the correlations for viral protein lengths are identical for both species, even though their average lengths differ. • Coronaviridae, Flaviviridae: human-infecting viral families. • Generalized statistical models describe viral RNA distribution behavior. • Comparison of viral protein length distributions using Bayesian analysis. • Despite differences, Coronaviridae and Flaviviridae display similar correlations. [ABSTRACT FROM AUTHOR]

In asphalt mixtures, external loading transfer paths can be deemed as force chains. The force chains difference can be used to evaluate skeleton structure. In this study, various asphalt mixture virtual specimens were established via discrete-element method (DEM) to investigate force chains length distribution and skeleton composition. Results indicate that, although dense-graded asphalt mixtures (AC) generate a large number of force chains compared with stone mastic asphalt (SMA) and open-graded asphalt friction course (OGFC), most of them are shorter length force chains that are not conductive to transfer external loading. When asphalt mixtures were penetrated to the same depth, asphalt mixtures with smaller nominal maximum aggregate size (NMAS) need more force chains to transfer external loading. In asphalt mixtures, the increase of NMAS can help to form longer length force chains. The passing percentage of 2.36 mm (P2.36) increase can lead to form more short length force chains. In asphalt mixtures, less than 50% quantity aggregates participate in skeleton composition. The aggregates within 2.36 mm participate in skeleton composition for AC16. Skeleton composition difference between AC and skeleton type asphalt mixtures is mainly affected by P2.36. [ABSTRACT FROM AUTHOR]

This paper established a new viscoelastic-viscoplastic (VE-VP) constitutive model of glassy polymers, where the non-uniform length distribution of entangled network is applied in the calculation of activation of the entangled network. The stress induced by activated sub-chains is releasable, thus, the viscoelastic behavior of glassy polymer in the small deformation stage is modeled. The present model shows great accuracy in predicting the uniaxial tensile, stress relaxation and dynamic thermomechanical behavior of the PFSA membrane, providing a new perspective of constitutive modeling for glassy polymers. [Display omitted] • Constitutive model of glassy polymers is built based on microscopic mechanism. • The entanglement length distribution is applied in constitutive modeling. • The model accurately captures the VE-VP behavior of PFSA membrane. Glassy polymers are common engineering materials and usually work in a linear elastic stage. However, some functional glassy polymers, such as perfluorinated sulfonic acid (PFSA) membranes, face more complicated working conditions: varied temperature, humidity, and long-term loading, where the viscoelastic behavior has a huge impact on their durability. The early studies on the constitutive model of glassy polymers focus on the elastic–plastic behavior, especially yielding and strain hardening, while showing limitations in predicting the time-dependent viscoelastic response of the PFSA membrane at complex conditions. This paper establishes a viscoelastic-viscoplastic (VE-VP) constitutive model of glassy polymers based on the non-uniform length distribution of entangled molecular chains. During loading, heating and hydration, the prior activation of short entangled chains is the precondition of the viscoelastic response of the material in the small deformation stage. To distinguish activated molecular chains from others, a calculation method of chain activation is established based on the energy conservation criterion and applied to monitor the activation state of the entangled chain network. For the verification of the model, uniaxial tensile, stress relaxation, and dynamic thermomechanical tests are conducted. The present model shows great accuracy in predicting the VE-VP behavior of the PFSA membrane, with the error less than 8% in the stress relaxation tests, providing a new perspective of constitutive modeling for glassy polymers. [ABSTRACT FROM AUTHOR]

The dual-beard image method, which has been developed in recent years as a fast and economical method for fiber length measurement, consists of dual-beard specimen preparation, image processing, fibrogram extraction, and length parameter calculations. However, one of the shortcomings of this method is that it can only produce extremely limited length parameters such as mean length, coefficient of variation, modal length, and quality length (UHML, upper half mean length). This study introduces a new algorithm for converting the dual-beard fibrogram into a length distribution histogram which can be used to calculate most of the current length parameters. The algorithm is based on the short fiber content formulae but modified by theoretical analysis and experimental comparison. The length distributions of 24 cotton samples and 12 wool samples are measured by dual-beard image method with the new algorithm, and Advanced Fiber Information System (AFIS) and Almeter are employed for comparison. Comparative analysis shows that the peaks and ranges of the distribution histograms using the dual-beard method are similar to those from the reference methods, and the shapes of histograms from difference methods match well with one another. In addition, five length parameters calculated from the dual-beard distributions are verified to be consistent with those measured by AFIS and Almeter. The new algorithm employed in the dual-beard image method avoids the differential operation which amplifies the curve error, giving the dual-beard image method the ability to output more comprehensive length information. [ABSTRACT FROM AUTHOR]

Background: Phosphate is an essential plant macronutrient required to achieve maximum crop yield. Roots are able to uptake soil phosphate from the immediate root area, thus creating a nutrient depletion zone. Many plants are able to exploit phosphate from beyond this root nutrient depletion zone through symbiotic association with Arbuscular Mycorrhizal Fungi (AMF). Here we characterise the relationship between root architecture, AMF association and low phosphate tolerance in strawberries. The contrasting root architecture in the parental strawberry cultivars 'Redgauntlet' and 'Hapil' was studied through a mapping population of 168 progeny. Low phosphate tolerance and AMF association was quantified for each genotype to allow assessment of the phenotypic and genotypic relationships between traits. Results: A "phosphate scavenging" root phenotype where individuals exhibit a high proportion of surface lateral roots was associated with a reduction in root system size across genotypes. A genetic correlation between "root system size" traits was observed with a network of pleiotropic QTL found to represent five "root system size" traits. By contrast, average root diameter and the distribution of roots appeared to be under two discrete methods of genetic control. A total of 18 QTL were associated with plant traits, 4 of which were associated with solidity that explained 46% of the observed variation. Investigations into the relationship between AMF association and root architecture found that a higher root density was associated with greater AMF colonisation across genotypes. However, no phenotypic correlation or genotypic association was found between low phosphate tolerance and the propensity for AMF association, nor root architectural traits when plants are grown under optimal nutrient conditions. Conclusions: Understanding the genetic relationships underpinning phosphate capture can inform the breeding of strawberry varieties with better nutrient use efficiency. Solid root systems were associated with greater AMF colonisation. However, low P-tolerance was not phenotypically or genotypically associated with root architecture traits in strawberry plants. Furthermore, a trade-off was observed between root system size and root architecture type, highlighting the energetic costs associated with a "phosphate scavenging" root architecture. [ABSTRACT FROM AUTHOR]

• The formation rate of polyynes increased with the rising carbon-hydrogen ratio of the alkane precursor, and the alkanes affect the length distribution of polyyne chains. • This paper indicates that the energy consumed by the precursor molecules to generate equal amounts of C 2 radicals has an important effect on the formation rate of polyynes, and the volume density of C 2 radicals has a certain regulatory effect on the length distribution of polyyne chains. • This study provides technical information and propensity rule for selecting appropriate precursor molecules to increase the yield of polyynes and to prepare polyyne samples of the desired chain length distribution. Polyynes were synthesized by arc discharge between two copper electrodes in alkanes for the first time. The as-grown polyyne samples were separated through high-performance liquid chromatography and the size-selected polyynes C 2n H 2 (n = 4–6) were investigated by surface-enhanced Raman scattering spectroscopy. The formation rate of polyynes has been found to increase with rising carbon-hydrogen ratio of the alkanes, and the alkanes affect the length of polyyne chains. The reaction enthalpy from alkane to C 2 radicals decreases with increasing carbon-hydrogen ratio, which causes the energy consumption in the whole reaction to differ and leads to different formation rates. [ABSTRACT FROM AUTHOR]

Background. In Turkey, the Mediterranean scaldfish, Arnoglossus laterna (Walbaum, 1792), is a discard fish species and it has a ‘least concern’ status on the IUCN Red List which indicates a low extinction risk. Although there are some studies investigating biology of this species, the knowledge of the mortality rates, spawning period, first maturity size, and age are not available for the study area. This paper, for the first time, provides some data on unknown population parameters for the east-central Aegean Sea. The aim of the presently reported study was to expand our knowledge on the biology of A. laterna. Materials and methods. Specimens of A. laterna were collected at monthly intervals by bottom trawl hauls between July 2004 and June 2007 from İzmir Bay (Turkey). The total length (L, cm), total weight (W, g), gonad weight (WG, g), and the sex were determined and the sagittal otolith pairs were removed for age reading. The length–weight relations were estimated by linear regression analysis on log-transformed data by equation: W = aLb. The growth was analysed by fitting the VBGF to size-at-age data using standard nonlinear optimization methods. Spawning period was established with monthly variations of the GSI values. Length at first maturity was estimating by the logit function. Results. A total of 2469 A. laterna individuals were sampled and the sex ratio was calculated as 1 ÷ 1.57 (F ÷ M). The length range of the sample was from 4.4 to 19.8 cm and the mean length was calculated as 9.4 ± 0.05 cm. For all samples, the length–weight relation was (W = 0.0074L3.04) and the growth type was determined as positive allometric. The age distribution of individuals varied from the ages of 1 to 8 years and the growth equation was determined as Lt = 20.62[1 – e–0.245(t + 1.071)]. The first maturity lengths were estimated as 11.88 cm for females and 11.41 cm for males. Conclusion. The presently reported study provides the age, growth, and reproduction parameters for A. laterna and the first information on the mortality rates, spawning period, first maturity size, and age parameters for the east-central Aegean Sea. These parameters can be useful for managers in the management and conservation of the stock.

Climate change studies have long focused on effects of increasing temperatures, often without considering other simultaneously occurring environmental changes, such as browning of waters. Resolving how the combination of warming and browning of aquatic ecosystems affects fish biomass production is essential for future ecosystem functioning, fisheries, and food security. In this study, we analyzed individual‐ and population‐level fish data from 52 temperate and boreal lakes in Northern Europe, covering large gradients in water temperature and color (absorbance, 420 nm). We show that fish (Eurasian perch, Perca fluviatilis) biomass production decreased with both high water temperatures and brown water color, being lowest in warm and brown lakes. However, while both high temperature and brown water decreased fish biomass production, the mechanisms behind the decrease differed: temperature affected the fish biomass production mainly through a decrease in population standing stock biomass, and through shifts in size‐ and age‐distributions toward a higher proportion of young and small individuals in warm lakes; brown water color, on the other hand, mainly influenced fish biomass production through negative effects on individual body growth and length‐at‐age. In addition to these findings, we observed that the effects of temperature and brown water color on individual‐level processes varied over ontogeny. Body growth only responded positively to higher temperatures among young perch, and brown water color had a stronger negative effect on body growth of old than on young individuals. Thus, to better understand and predict future fish biomass production, it is necessary to integrate both individual‐ and population‐level responses and to acknowledge within‐species variation. Our results suggest that global climate change, leading to browner and warmer waters, may negatively affect fish biomass production, and this effect may be stronger than caused by increased temperature or water color alone. As lakes get warmer and browner, fish biomass production decreases through different pathways. Warming reduces population biomass and induces a shift toward smaller and younger individuals, whereas browning leads to slower body growth. Our study shows that it is necessary to study multiple climate stressors and both individual‐ and population‐level responses to understand and predict shifts in fish biomass production in a changing climate. [ABSTRACT FROM AUTHOR]

Abstract Single walled carbon nanotubes (SWCNTs) are sliced with control over their length distribution within a laser irradiated dynamic thin film in a vortex fluidic device (VFD) operating under continuous flow conditions. Length control depends on the laser pulse energy, the flow rate of the liquid entering the device, the speed of the rapidly rotating tube and its tilt angle, choice of solvent and concentration of the as received SWCNTs. The induced mechanoenergy in the thin film while being simultaneously irradiated with a Nd:YAG pulsed laser operating at 1064 nm wavelength results in the slicing, with laser pulse energies of 250, 400 and 600 mJ affording 700, 300 and 80 nm length distributions of SWCNTs respectively. The processing avoids the need for using any other reagents, is scalable under continuous flow conditions, and does not introduce defects into the side walls of the SWCNTs. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

We investigate the ratio ρ n , L of prefix codes to all uniquely decodable codes over an n -letter alphabet and with length distribution L . For any integers n ≥ 2 and m ≥ 1 , we construct a lower bound and an upper bound for inf L ρ n , L , the infimum taken over all sequences L of length m for which the set of uniquely decodable codes with length distribution L is non-empty. As a result, we obtain that this infimum is always greater than zero. Moreover, for every m ≥ 1 it tends to 1 when n → ∞ , and for every n ≥ 2 it tends to 0 when m → ∞ . In the case m = 2 , we also obtain the exact value for this infimum. [ABSTRACT FROM AUTHOR]

Natural fractures are ubiquitous in the Earth’s crust and often deeply buried in the subsurface. Due to the difficulty in accessing to their three-dimensional structures, the study of fracture network geometry is usually achieved by sampling two-dimensional (2D) exposures at the Earth’s surface through outcrop mapping or aerial photograph techniques. However, the measurement results can be considerably affected by the coverage of forests and other plant species over the exposed fracture patterns. We quantitatively study such effects using numerical simulation. We consider the scenario of nominally isotropic natural fracture systems and represent them using 2D discrete fracture network models governed by fractal and length scaling parameters. The groundcover is modelled as random patches superimposing onto the 2D fracture patterns. The effects of localisation and total coverage of landscape patches are further investigated. The fractal dimension and length exponent of the covered fracture networks are measured and compared with those of the original non-covered patterns. The results show that the measured length exponent increases with the reduced localisation and increased coverage of landscape patches, which is more evident for networks dominated by very large fractures (i.e. small underlying length exponent). However, the landscape coverage seems to have a minor impact on the fractal dimension measurement. The research findings of this paper have important implications for field survey and statistical analysis of geological systems. [ABSTRACT FROM AUTHOR]

The use of borehole image logs in natural-fracture evaluation has traditionally focused on mapping the strikes and dips of the individual fractures that intersect the borehole, estimating their apertures, and from these computing fracture attributes such as fracture density. These fracture attributes are commonly used to build three-dimensional fracture-network models. However, these attributes do not directly constrain an important aspect of these models—fracture geometry—specifically, the size, shape, and rotation of three-dimensional fractures within the model. The published formulas of Ozkaya estimate the radius of circular fractures from the statistics of fracture intersections observed in a borehole image. These formulas are shown to be approximate, only applying to circular fractures with shallow relative dip, and are replaced with exact formulas for elliptical fractures that are valid over the entire range of relative dip. A new statistic is defined, the measured distribution of relative azimuths for fracture-trace midpoints, that is sufficient for estimating both the elongation ratio and the rotation angle of elliptically shaped fractures. As estimation accuracy for this fracture geometry is dependent on the number of observed fracture traces, practical methodologies are provided for computing the uncertainty of these estimates. Finally, since natural fracture size is typically not constant, but follows a distribution such as a power law, solutions are provided for using these same borehole image statistics to estimate the fracture-size distribution. Numerical examples with exponential and Pareto distributions demonstrate that a single parameter of a parametric size distribution can be estimated along with its uncertainty. [ABSTRACT FROM AUTHOR]

In this study, the fiber-shift method is presented to generate the three-dimensional geometric model of carbon fiber needled felt, and curved carbon fiber is regarded as beam under pure bending. The finite mixture model is applied to describe the fiber length distribution for the experiments and models. Closed model, open model and cut model are proposed, and cut model is thought to be more close to reality. A series of analytical methods are proposed to investigate the full-scale three-dimensional geometric model. The fiber-length distributions of cut models with different dimensions are obtained. The results show that, with the increasing of border length of cut model, the percentage of carbon fiber been cut is getting smaller, and the average fiber length is increased. In addition, the compression and needling process of pre-needling technique are simulated, and the needling hole obtained by simulation is similar to reality. [ABSTRACT FROM AUTHOR]

Aqueous nanocellulose dispersions were prepared from wood cellulose by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The obtained TEMPO-oxidized cellulose was converted into TEMPO-oxidized cellulose nanofibrils (TOCNs) of different lengths by controlling the nanofibrillation conditions in water or using dilute acid hydrolysis. The average lengths and length distributions of TOCNs have been measured from transmission electron microscopy (TEM) and atomic force microscopy (AFM) images. However, because the number of nanocelluloses observable in TEM and AFM images is limited, a more reliable method is needed to obtain the lengths/length distributions of TOCNs. In this study, the aqueous TOCN dispersions were subjected to a combination of field-flow fractionation (FFF) and multi-angle laser-light scattering (MALLS). The optimum FFF operation conditions for the acid-hydrolyzed TOCN were first established to obtain reasonable data. For TOCNs with average lengths > 400 nm, suitable separation could not be achieved using the FFF/MALLS system. In contrast, the TOCNs with average lengths of 170 and 270 nm were adequately separated according to their sizes by the FFF system. The TOCN length distribution patterns corresponded well to those obtained from TEM images. However, the amounts of TOCNs with lengths > 250 nm were underestimated compared with those determined from TEM images. For TOCNs with average lengths of 170 and 270 nm, the molar mass at each TOCN length was determined using the FFF/MALLS system combined with a refractive index detector, where a specific refractive index increment of 0.165 mL/g was used for TOCN. [ABSTRACT FROM AUTHOR]

Background: Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. Results: Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. Conclusion: Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems might exist outside of the cyanobacterial phylum, which might be capable of driving diurnal oscillations. [ABSTRACT FROM AUTHOR]

Reproducible integration of III–V semiconductors on silicon can open new path toward CMOS compatible optoelectronics and novel design schemes in next generation solar cells. Ordered arrays of nanowires could accomplish this task, provided they are obtained in high yield and uniformity. In this work, we provide understanding on the physical factors affecting size uniformity in ordered GaAs arrays grown on silicon. We show that the length and diameter distributions in the initial stage of growth are not much influenced by the Poissonian fluctuation-induced broadening, but rather are determined by the long incubation stage. We also show that the size distributions are consistent with the double exponential shapes typical for macroscopic nucleation with a large critical length after which the nanowires grow irreversibly. The size uniformity is dramatically improved by increasing the As4 flux, suggesting a new path for obtaining highly uniform arrays of GaAs nanowires on silicon. [ABSTRACT FROM AUTHOR]

Ultra-short carbon nanotubes (CNTs) have many unique features but cutting CNTs to below 100 nm is still challenging. Herein, we explore a new high-speed shearing process based on the shearing force-assisted compressing force process to cut CNTs, which is different from the conventional mechanical process based on compressing force. The optimal balance of CNTs length (47.2 ± 22.3 nm) and structural integrity was achieved after the high-speed shearing process at 1500 rpm for 15 min, after that, the length reduction of CNTs was not obvious but the structure was damaged significantly. The molecular dynamics simulation shows that shearing force is more beneficial to fracture CNTs into several segments along their axial direction and assists compressing force to cut CNTs by reducing the critical compressing force and energy consumption. The cutting length of CNTs by high-speed ball milling was above 100 nm because the compressing force tends to compact CNTs clusters and squash the CNTs along their radial direction rather than cutting CNTs along their axis direction. Our work provides a new perspective for the scalable manufacturing of ultra-short CNTs below 100 nm for various specific applications. [Display omitted] • Multi-walled CNTs with an average length of ~50 nm was obtained. • Multi-walled CNTs were firstly cut by a new high-speed shearing process. • The shearing force assists compressing force to cut CNTs. [ABSTRACT FROM AUTHOR]

The Vaca Muerta Formation is the main source rock of the Neuquén Basin in Argentina. The interest in this unit has grown over the years as it is considered an excellent unconventional exploration target. It is characterized by a naturally fractured succession of dark organic-rich shales deposited due to a marine transgression during the Late Jurassic to Early Cretaceous. In the Sierra de la Vaca Muerta area, the southernmost sector of the Agrio fold and thrust belt, a carbonate-dominated interval in the Vaca Muerta Formation is outcropping characterized by tabular micritic limestones intercalated with marls known as the Los Catutos Member. This member usually exposed large pavements that allow good observations of the fracture pattern and lengths. We performed a natural fracture network analysis over the mid-upper Tithonian Los Catutos Member outcrops. 585 fractures were measured in the field, and 665 fracture traces were manually mapped using an aerial image acquired by an unmanned aerial vehicle (UAV). Four main sub-perpendicular to the bedding fracture sets were identified, trending WNW-ESE, N–S, NW-SE, and NE-SW. The fracture length distribution was analyzed using the maximum likelihood estimator technique, revealing a lognormal distribution as the best fit for the sets recognized in the UAV image (WNW-ESE, N–S, and NE-SW). Also, the fracture system was classified as stratabound given the spatial and length distribution. The relative chronology between the four fracture sets was established based on the observed abutting relationships; furthermore, based on a fold test, a pre-folding origin was deduced. Finally, a regional interpretation for fracture formation is proposed considering the structure and tectonic history of the basin. The WNW-ESE oriented set formed by the longest fractures together with the orthogonal N–S oriented cross-joints, give rise to a ladder pattern; this arrangement likely responds to an along-foredeep stretching scenario that characterized this area during the Paleocene. Then, the NW-SE and NE-SW oriented fracture sets were emplaced, probably associated with the layer parallel shortening phase installed before the onset of major thrusting and folding from the late Miocene onwards. • A natural fracture network characterization over the Los Catutos Member in the Vaca Muerta Formation in the Sierra de la Vaca Muerta. • Four main fracture sets trending WNW-ESE, N–S, NE-SW and NW-SE were identified in outcrops, and the first three in the UAV interpretation. • Fracture lengths of sets WNW-ESE, N–S and NE-SW are best fitted with a lognormal distribution. • A ladder-pattern is formed by sets WNW-ESE and N–S fractures resulting from a single deformational event. [ABSTRACT FROM AUTHOR]