Sieving Technique Research Articles

A new method for decomposition in the Jacobian of small genus hyperelliptic curves

Decomposing a divisor over a suitable factor basis in the Jacobian of a hyperelliptic curve is a crucial step in an index calculus algorithm for the discrete log problem in the Jacobian. For small genus curves, in the year 2000, Gaudry had proposed a suitable factor basis and a decomposition method. In this work, we provide a new method for decomposition over the same factor basis. The advantage of the new method is that it admits a sieving technique which removes smoothness checking of polynomials required in Gaudry’s method. Also, the total number of additions in the Jacobian required by the new method is less than that required by Gaudry’s method. The new method itself is quite simple and we present some example decompositions and timing results of our implementation of the method using Magma.

Abstract P040: Role of 20-HETE in Elevated Blood Pressure in Hyperandrogenemic Female Rats, a Model of Polycystic Ovarian Syndrome

Polycystic ovary syndrome (PCOS) is the most common reproductive disorder in premenopausal women, is characterized by hyperandrogenemia, metabolic syndrome and inflammation. They also exhibit elevated blood pressure (BP) but may not be treated since they do not meet the criteria for hypertension (BP>130/90 mm Hg). We have characterized a female rat model of hyperandrogenemia (HAF) using dihydrotestosterone (DHT) that mimics many characteristics of women with PCOS. In the present study we tested the hypothesis that androgen-induced upregulation of the cytochrome P450 4A2 isoform (CYP4A2) and the formation of 20-hydroxyeicosatetraenoic acid (20-HETE) in renal microvasculature contributes to the elevated BP in HAF rats. Female rats of SS.5BN consomic strain (wild type) rats and CYP4A2-/- rats on this same background were implanted with DHT (7.5mg/90d) or placebo pellets (n=5-8/grp) beginning at 6 wks of age; pellets were changed every 85 d. At 14 wks of age, rats were implanted with radiotelemetry transmitters, and mean arterial pressure (MAP) was measured for 10 days. Endogenous 20-HETE levels were measured using LC-MS in renal microvessels isolated using an Evans Blue sieving technique. DHT-treated HAF-SS.5BN rats had significantly higher MAP compared to placebo-SS.5BN (128±6 vs. 104±1 mmHg, p<0.004). In contrast, HAF-CYP4A2-/- rats had no change in MAP compared to placebo-CYP4A2-/- controls (120±4 vs 118±3 mmHg, p=NS). Endogenous 20-HETE levels in renal microvessels of HAF-SS.5BN rats were significantly increased compared to Placebo-SS.5BN (2.27±0.91 vs. 0.32±0.037 pmol/mg, p<0.01). The 20-HETE levels were lower in CYP4A2-/- than SS.5BN but DHT in HAF-CYP4A2-/- had no effect on 20-HETE levels compared to Placebo- CYP4A2-/-. These results suggest that androgen-mediated upregulation of the expression of CYP4A2 and the production of 20-HETE in renal microvessels contribute to elevated BP in HAF rats. These data also suggest that methods to attenuate 20-HETE may provide a novel therapeutic to reduce BP in women with PCOS. Work supported by NIH RO1HL66072 and PO1HL51971.

Homogeneous matrix deposition on dried agar for MALDI imaging mass spectrometry of microbial cultures.

Matrix deposition on agar-based microbial colonies for MALDI imaging mass spectrometry is often complicated by the complex media on which microbes are grown. This Application Note demonstrates how consecutive short spray pulses of a matrix solution can form an evenly closed matrix layer on dried agar. Compared with sieving dry matrix onto wet agar, this method supports analyte cocrystallization, which results in significantly more signals, higher signal-to-noise ratios, and improved ionization efficiency. The even matrix layer improves spot-to-spot precision of measured m/z values when using TOF mass spectrometers. With this technique, we established reproducible imaging mass spectrometry of myxobacterial cultures on nutrient-rich cultivation media, which was not possible with the sieving technique. Graphical Abstract ᅟ.

Separation of Energy-rich Fractions from Lignite Mining Waste Using the Wet Sieving Technique

More than 50% of the gross reserves of Giral block, Barmer district, western Rajasthan are low grade having a calorific value less than 2,150 kcal/kg; therefore, it does not possess significant market values as a combustible fuel. The clay lignite inter-burden waste has been transformed into marketable high calorie carbonaceous fuel, fit for on the site power generation, manufacture of cement, manufacture of tiles and bricks, using a wet sieving technique. This material was transformed into a value-added product of CV (+) 2,754 kcal/kg. The separation was highly successful with more than 58% recovery. The separation technique involved the inherent self-disintegration behavior of the mineral in water followed by wet sieving and separating +1 mm fraction.

Testing of the consistency of the sieving (wash-over) process of waterlogged sediments by multiple operators

The sieving process has a considerable influence on the subsequently retrieved archaeobotanical data. As known from earlier work, the wash-over method is the most suitable method to extract plant macroremains from waterlogged sediments. This paper presents an experiment in which it was tested if different sievers using this method produced comparable results.Some systematic differences between sievers were found in the larger fractions (≥2mm), namely the varying presence of small remains. This problem can be avoided if detailed instructions are given to the sievers and guidelines for counting remains are used during analysis. In the small fraction (>0.35mm), differences between sievers were not substantial anymore. In addition to differences caused by the sieving technique we could also show that the patchy pattern of clumpy waterlogged sediments complicates a statistically relevant subsampling. We can state that only large differences between samples should be interpreted in palaeoeconomic terms, but that it is no disadvantage if several sievers work on the same project.It is our purpose to raise awareness of the fact that the methodology has a strong impact on the results obtained and should therefore always be revealed on a detailed level, especially if data from one site will later be used for comparisons with other sites.

Constrained Multilinear Detection and Generalized Graph Motifs

We introduce a new algebraic sieving technique to detect constrained multilinear monomials in multivariate polynomial generating functions given by an evaluation oracle. The polynomials are assumed to have coefficients from a field of characteristic two. As applications of the technique, we show an $$O^*(2^k)$$O?(2k)-time polynomial space algorithm for the $$k$$k-sized Graph Motif problem. We also introduce a new optimization variant of the problem, called Closest Graph Motif and solve it within the same time bound. The Closest Graph Motif problem encompasses several previously studied optimization variants, like Maximum Graph Motif, Min-Substitute Graph Motif, and Min-Add Graph Motif. Finally, we provide a piece of evidence that our result might be essentially tight: the existence of an $$O^*((2-\epsilon )^k)$$O?((2-∈)k)-time algorithm for the Graph Motif problem implies an $$O((2-\epsilon ')^n)$$O((2-∈?)n)-time algorithm for Set Cover.

Bias Correction of Persistence Measures in Fractionally Integrated Models

This article investigates the accuracy of bootstrap‐based bias correction of persistence measures for long‐memory fractionally integrated processes. The bootstrap method is based on the semi‐parametric sieve approach, with the dynamics in the long‐memory process captured by an autoregressive approximation. With a view to improving accuracy, the sieve method is also applied to data prefiltered by a semi‐parametric estimate of the long‐memory parameter. Both versions of the bootstrap technique are used to estimate the finite‐sample distributions of the sample autocorrelation coefficients and the impulse response coefficients and, in turn, to bias adjust these statistics. The accuracy of the resultant estimators in the case of the autocorrelation coefficients is also compared with that yielded by analytical bias adjustment methods when available. The basic sieve technique is seen to yield a reduction in the bias of both persistence measures. The prefiltered sieve produces a substantial further reduction in the bias of the estimated impulse response function, whilst the extra improvement yielded by prefiltering in the case of the sample autocorrelation function is shown to depend heavily on the accuracy of the prefilter.

Trend analysis of Trichinella in a red fox population from a low endemic area using a validated artificial digestion and sequential sieving technique.

Freezing of fox carcasses to minimize professional hazard of infection with Echinococcus multilocularis is recommended in endemic areas, but this could influence the detection of Trichinella larvae in the same host species. A method based on artificial digestion of frozen fox muscle, combined with larva isolation by a sequential sieving method (SSM), was validated using naturally infected foxes from Latvia. The validated SSM was used to detect dead Trichinella muscle larvae (ML) in frozen muscle samples of 369 red foxes from the Netherlands, of which one fox was positive (0.067 larvae per gram). This result was compared with historical Trichinella findings in Dutch red foxes. Molecular analysis using 5S PCR showed that both T. britovi and T. nativa were present in the Latvian foxes, without mixed infections. Of 96 non-frozen T. britovi ML, 94% was successfully sequenced, whereas this was the case for only 8.3% of 72 frozen T. britovi ML. The single Trichinella sp. larva that was recovered from the positive Dutch fox did not yield PCR product, probably due to severe freeze-damage. In conclusion, the SSM presented in this study is a fast and effective method to detect dead Trichinella larvae in frozen meat. We showed that the Trichinella prevalence in Dutch red fox was 0.27% (95% CI 0.065-1.5%), in contrast to 3.9% in the same study area fifteen years ago. Moreover, this study demonstrated that the efficacy of 5S PCR for identification of Trichinella britovi single larvae from frozen meat is not more than 8.3%.

SEDIMENT TRANSPORT PATHWAYS DETERMINED FROM GRAIN CHARACTERISTICS BASED ON DIGITAL IMAGES

â' The grain size accumulation curve obtained by an image picture is comparable as the mechanical sieving technique â'¡With decreasing of the diameter of sand grain, the value of roundness increases. So the shape of sand grain gets in a perfect circle and the distributions of roundness frequency show the Gaussian distribution.â'¢The sediment path way along the beaches on Awaji Island estimated by the expanded model corresponds to observation data very well.â'£The statistical significant level of the expanded model for sediment transport path way increases with introducing the value of roundness.

Technical Note: The Use of Laser Diffraction Particle Size Analyzers for Inference on Infauna-Sediment Relationships

For over a century, ecologists and evolutionary biologists have investigated the association between sedimentary characteristics and the infaunal communities inhabiting sediments. Relationships between infauna and, specifically, sediment grain size distributions, have provided a common methodology to predict the distributions, composition, and diversity of soft-sediment communities. Wet/dry sieve methods have traditionally been used to determine grain size distributions, but laser particle size analyzers are becoming increasingly popular and have been shown to measure sediment grain size distributions more efficiently and more accurately than wet/dry sieve methods. An additional, but underexplored, advantage of laser particle size analyzers is their ability to provide uncommonly reported or alternative grain size statistics that can be used to estimate sediment characteristics that are not easily measured using sieve techniques. In particular, measures of sediment heterogeneity are arbitrary and tedious to measure with previously used sieve and microscope techniques. Here, we propose that grain size coefficient of variation, measured using a particle size analyzer, is an improved metric for sediment heterogeneity. We show that grain size coefficient of variation is related to infaunal richness in intertidal habitats along the northern Gulf of Mexico matching previous results relating sediment heterogeneity to infaunal richness. We discuss the benefits and drawbacks of particle size analyzers and how the use of alternative metrics from laser particle size analyzers may assist the field of benthic ecology.

Analysis of Grain Size Statistic and Particle Size Distribution of Biomass Powders

An investigation was made of relevant physical properties of two types of biomass: bagasse and cotton stalk powders. Three samples of each biomass were analyzed, and the average value of the mass retained in each sieve of the three samples was taken. Any study incorporating grain size analysis must include a clear statement of the measurement technique and the method used in the calculation of any statistics. It will be appropriate to employ more than one method, since comparison of results obtained in different ways may provide additional insight into the processes involved. In this work, the particle size distribution was calculated by three various methods. These methods are sieving analysis, statistical calculations and image analysis (i.e. microscopy). Sieving analysis has been done mechanically using a mechanical sieve shaker and a series of nested sieves. A computer program called GRADISTAT has been used for the rapid analysis of grain size statistics from the standard measuring sieving techniques. Statistical parameters of mean, median, standard deviation, skewness and kurtosis are calculated arithmetically and geometrically (in metric units) and logarithmic (in phi units) using moment and Folk and Ward graphical methods.

Assessment of the Relationship between ESR Signal Intensity and Grain Size Distribution in Shear Zones within the Atotsugawa Fault System, Central Japan

For the first time, a relationship between ESR signal intensity and grain size distribution (sieve technique) in shear zones within the Atotsugawa fault system have been investigated using fault core rocks. The grain size distributions were estimated using the sieve technique and microscopic observations. Stacks of sieves with openings that decrease consecutively in the order of 4.75 mm, 1.18 mm, 600 μm, 300 μm, 150 μm and 75 μm were chosen for this study. Grain size distributions analysis revealed that samples further from the slip plane have larger d50 (average gain size) (0.45 mm at a distance of 30 - 50 mm from the slip plane) while those close to the slip plane have smaller d50 values (0.19 mm at a distance of 0 - 10 mm from the slip plane). This is due to intensive crushing that is always associated with large displacement during fault activities. However, this pattern was not respected in all shear zones in that, larger d50 values were instead observed in samples close to the slip plane due to admixture of fault rocks from different fault activities. Results from ESR analysis revealed that the relatively finer samples close to the slip plane have low ESR signals intensity while those further away (coarser) have relatively higher signal intensity. This tendency however, is not consistence in some of the shear zones due to a complex network of anatomizing faults. The variation in grain size distribution within some of the shear zones implies that, a series of fault events have taken place in the past thus underscoring the need for further investigation of the possibility of reoccurrence of faults.

Increase in number of helminth species from Dutch red foxes over a 35-year period

BackgroundThe red fox (Vulpes vulpes) is host to a community of zoonotic and other helminth species. Tracking their community structure and dynamics over decades is one way to monitor the long term risk of parasitic infectious diseases relevant to public and veterinary health.MethodsWe identified 17 helminth species from 136 foxes by mucosal scraping, centrifugal sedimentation/flotation and the washing and sieving technique. We applied rarefaction analysis to our samples and compared the resulting curve to the helminth community reported in literature 35 years ago.ResultsFox helminth species significantly increased in number in the last 35 years (p-value <0.025). Toxascaris leonina, Mesocestoides litteratus, Trichuris vulpis and Angiostrongylus vasorum are four new veterinary-relevant species. The zoonotic fox tapeworm (E. multilocularis) was found outside the previously described endemic regions in the Netherlands.ConclusionsHelminth fauna in Dutch red foxes increased in biodiversity over the last three decades.

Deterministic elliptic curve primality proving for a special sequence of numbers

We give a deterministic algorithm that very quickly proves the primality or compositeness of the integers N in a certain sequence, using an elliptic curve E/Q with complex multiplication by the ring of integers of Q(sqrt(-7)). The algorithm uses O(log N) arithmetic operations in the ring Z/NZ, implying a bit complexity that is quasi-quadratic in log N. Notably, neither of the classical "N-1" or "N+1" primality tests apply to the integers in our sequence. We discuss how this algorithm may be applied, in combination with sieving techniques, to efficiently search for very large primes. This has allowed us to prove the primality of several integers with more than 100,000 decimal digits, the largest of which has more than a million bits in its binary representation. At the time it was found, it was the largest proven prime N for which no significant partial factorization of N-1 or N+1 is known.

Improved techniques for computing the ideal class group and a system of fundamental units in number fields

We describe a new algorithm for computing the ideal class group, the regulator and a system of fundamental units in number fields under the generalized Riemann hypothesis. We use sieving techniques adapted from the number field sieve algorithm to derive relations between elements of the ideal class group, and p-adic approximations to manage the loss of precision during the computation of units. This new algorithm is particularily efficient for number fields of small degree for which a speed-up of an order of magnitude is achieved with respect to the standard methods.

Plant macro remains from Early Historic Vessel, Gilund, Rajasthan

The macrobotanical remains were recovered from the Early Historic vessel from Gilund, Rajasthan by employing dry and wet sieving techniques in the Palaeobotany laboratory. The retrieved archaeobotanical material was in carbonized and semi-carbonized state. It involves cultivated barley grains, a single cut grain of rice and a seeds of weed plant along with a bulk of wood charcoal pieces. These could survive in the carbonized state by being exposed to heat or fire. The impressions of grass leaves were found on well backed brickbats occurred in the vessel. Few molluscan shells were also retrieved during wet sieving.

Exploiting Image Processing and Analysis Versus Other Techniques for Composite Fines Particle Size and Shape Distribution Analysis

Reliable particles property distribution data is important in design of materials processing operation. With composite fines samples, such as the comminution fines in printed circuit board physical processing, having particles diverse in material type and morphology, size distribution data from some conventional techniques will not fully describe the sample. A review of basic analytical principles shows sieving, cyclosizing, and laser diffraction techniques will, in principle, return erroneous results. Rather, it was shown from test analysis carried out that detailed quantitative description of the particle size and shape distribution for such composite fines sample can be obtained by employing image processing and analysis of a good micrograph of the sample. Image processing with image analysis can be used to decompose the composite micrograph and separately characterize the constituent particle types. This is a good reference for composite fines size and shape distribution analysis, to narrow down applicable analytical techniques and avoid use of misleading data.

A bioarchaeological investigation of three late Chalcolithic pits at Ovçular Tepesi (Nakhchivan, Azerbaijan)

Socio-economic organisation, subsistence strategies and environmental exploitation still remain largely open questions for the Late Chalcolithic period (ca. 4500–3500 BC) in southern Caucasus even though they are of prime importance for understanding the development of post-Neolithic societies in these semi-arid and mountainous areas. Interdisciplinary bioarchaeological research can, however, provide valuable new insights into these issues. In the Late Chalcolithic occupation layers at Ovçular Tepesi (Nakhchivan Autonomous Republic, Azerbaijan), the fills of pits, composed mainly of domestic refuse, proved to contain the richest and most diverse assemblages of biological remains at the site. These remains, retrieved by the use of flotation and sieving techniques, therefore constitute ideal assemblages for understanding subsistence strategies and the exploitation of natural resources. It is shown here that the agricultural economy at Late Chalcolithic Ovçular Tepesi was based mainly on the cultivation of cereals and pulses and the herding of sheep and goat. The river and its surroundings provided wood fuel and fish. The results of the bioarchaeological study further suggest that the Late Chalcolithic village was occupied permanently as shown by the development of commensal populations of small mammals.

A Randomized Sieving Algorithm for Approximate Integer Programming

The Integer Programming Problem (IP) for a polytope $P \subseteq \mathbb{R} ^{n}$ is to find an integer point in P or decide that P is integer free. We give a randomized algorithm for an approximate version of this problem, which correctly decides whether P contains an integer point or whether a (1+∈)-scaling of P about its center of gravity is integer free in 2 O(n)(1/∈ 2) n -time and 2 O(n)(1/∈) n -space with overwhelming probability. Our algorithm proceeds by reducing the approximate IP problem to an approximate Closest Vector Problem (CVP) under a "near-symmetric" norm. Our main technical contribution is an extension of the AKS randomized sieving technique, first developed by Ajtai et al. (Proceedings of 33rd Symposium on the Theory of Computing (STOC), pp. 601---610, 2001) for lattice problems under the l 2 norm, to the setting of asymmetric norms. We also present an application of our techniques to exact IP, where we give a nearly optimal algorithmic implementation of the Flatness Theorem, a central ingredient for many IP algorithms. Our results also extend to general convex bodies and lattices.

Terrestrial Mollusc Species Richness and Diversity in Omo Forest Reserve, Ogun State, Nigeria

The terrestrial mollusc species richness and diversity in Omo Forest Reserve, Ogun State, Nigeria, was studied using a combination of direct search and leaf-litter sieving techniques. In total, 28 species and 639 individuals in 7 molluscan families were collected from 17 plots of 400 m2 each. Species richness varied from 3 to 14 (mean 8.59) and the number of individuals from 8 to 67 (mean 37.59) per plot. Species richness was dominated by the carnivorous Streptaxidae (36%) and herbivorous Subulinidae (32%), and numerical abundance by the Subulinidae (56%) and Streptaxidae (32%). The most abundant species was the large subulinid, Subulona pattalus, contributing almost 25% of the total number of individuals. Terrestrial molluscs with small populations and narrow distributional ranges are at great risk of local extinction if forest destruction continues unabated. Studies on the molluscan diversity in Omo Forest Reserve will assist in producing an inventory for biodiversity conservation management in Nigeria.