STATS - A Point Access Method for Multidimensional Clusters.

The ubiquity of high-dimensional data in machine learning and data mining applications makes its efficient indexing and retrieval from main memory crucial. Frequently, these machine learning algorithms need to query specific characteristics of single multidimensional points. For example, given a clustered dataset, the cluster membership (CM) query retrieves the cluster to which an object belongs. To efficiently answer this type of query we have developed STATS, a novel main-memory index which scales to answer CM queries on increasingly big datasets. Current indexing methods are oblivious to the structure of clusters in the data, and we thus, develop STATS around the key insight that exploiting the cluster information when indexing and preserving it in the index will accelerate look up. We show experimentally that STATS outperforms known methods in regards to retrieval time and scales well with dataset size for any number of dimensions

Effect of repeated applications of fipronil on arthropod populations in experimental plot studies

The effect of two applications of fipronil on arthropod populations were studied under experimental plot conditions using 3-month old Cuphea ignea. Eighty-one families belonging to 12 orders of Arthropoda were trapped before spraying. The four dominant orders were Hymenoptera (28.6%), Homoptera (19.1 %), Collembola (17.8 %) and Diptera (16.2 %). Other orders were present in small numbers i. e. Hemiptera, Coleoptera, Orthoptera, Thysanoptera, Araneida, Acarina, Lepidoptera and Isopoda. The abundance of arthropods was reduced to 44 and 47 families after the first and second sprayings, respectively. The percentage population of Collembola increased significantly after the first and second sprayings as compared to the number before treatment. The percentage population ofHomoptera (Aleyrodidae) increased after the first spray but declined after the second spray. The family Isotomidae (Collembola) increased significantly after the first and second sprays. Some orders such as Isopoda and Lepidoptera disappeared after the plot was treated with fipronil

Physico-chemical properties and quality of palm-based vegetable ghee

Samples of trans-free vegetable ghee were made using palm oil/palm stearin/palm olein (PO/POs/POo) blends (set A) and using palm oil/palm stearin/palm kernel olein (PO/POs/PKOo) blends (set B). Palm stearin of iodine value (IV) 30 was used in this study. The products were evaluated for their physical and chemical properties. Changes in quality during storage were monitored during a period of 16 weeks. Most of the vegetable ghee were granular (grainy) and had a shiny appearance. Chemical analyses indicated that vegetable ghee consisting of PO/POs/POo had higher IV (47.7-52.4) than the PO/POs/PKOo vegetable ghee due to their higher content of unsaturated fatty acids, 46.0-50.0% compared to 36.6-45.0% in Set B. Decreasing the amount of palm oil while increasing palm stearin in the formulations resulted in higher slip melting point (SMP) and higher yield values. Eutectic interaction was noted in PO/POs/PKOo blends. The crystals in samples PO/POs/POo (set A) were predominant in the §’ polymorphic form. One formulation in set B (B4) exhibited § crystallinity. Free fatty acids (FFA) were lowest in samples PO/POs/POo 80:5:15 (A4) and PO/POs:/PKOo 80:5:15 (B4) throughout storage. There was no clear trend on anisidine value (AV) while IV remained almost constant. Selected vegetable ghee, A4 wasused to shallow fry roti canai and for cooking nasi minyak. Sensory evaluation on these two products revealed that there was no significant difference (P < 0.05) in texture, taste and overall quality between samples A4 and B4

First passage time exponent for higher-order random walks:Using Levy flights

We present a heuristic derivation of the first passage time exponent for the integral of a random walk [Y. G. Sinai, Theor. Math. Phys. {\bf 90}, 219 (1992)]. Building on this derivation, we construct an estimation scheme to understand the first passage time exponent for the integral of the integral of a random walk, which is numerically observed to be $0.220\pm0.001$. We discuss the implications of this estimation scheme for the $n{\rm th}$ integral of a random walk. For completeness, we also address the $n=\infty$ case. Finally, we explore an application of these processes to an extended, elastic object being pulled through a random potential by a uniform applied force. In so doing, we demonstrate a time reparameterization freedom in the Langevin equation that maps nonlinear stochastic processes into linear ones.Comment: 4 figures, submitted to PR

Modifying the Symbolic Aggregate Approximation Method to Capture Segment Trend Information

The Symbolic Aggregate approXimation (SAX) is a very popular symbolic dimensionality reduction technique of time series data, as it has several advantages over other dimensionality reduction techniques. One of its major advantages is its efficiency, as it uses precomputed distances. The other main advantage is that in SAX the distance measure defined on the reduced space lower bounds the distance measure defined on the original space. This enables SAX to return exact results in query-by-content tasks. Yet SAX has an inherent drawback, which is its inability to capture segment trend information. Several researchers have attempted to enhance SAX by proposing modifications to include trend information. However, this comes at the expense of giving up on one or more of the advantages of SAX. In this paper we investigate three modifications of SAX to add trend capturing ability to it. These modifications retain the same features of SAX in terms of simplicity, efficiency, as well as the exact results it returns. They are simple procedures based on a different segmentation of the time series than that used in classic-SAX. We test the performance of these three modifications on 45 time series datasets of different sizes, dimensions, and nature, on a classification task and we compare it to that of classic-SAX. The results we obtained show that one of these modifications manages to outperform classic-SAX and that another one slightly gives better results than classic-SAX.Comment: International Conference on Modeling Decisions for Artificial Intelligence - MDAI 2020: Modeling Decisions for Artificial Intelligence pp 230-23

Models of plastic depinning of driven disordered systems

Two classes of models of driven disordered systems that exhibit history-dependent dynamics are discussed. The first class incorporates local inertia in the dynamics via nonmonotonic stress transfer between adjacent degrees of freedom. The second class allows for proliferation of topological defects due to the interplay of strong disorder and drive. In mean field theory both models exhibit a tricritical point as a function of disorder strength. At weak disorder depinning is continuous and the sliding state is unique. At strong disorder depinning is discontinuous and hysteretic.Comment: 3 figures, invited talk at StatPhys 2

Accumulation of Heavy Metals in Selected Vegetables, Their Availability and Correlation in Lithogenic and Nonlithogenic Fractions of Soils from Some Agricultural Areas in Malaysia

ABSTRACT Heavy metal content was determined in selected vegetables cultivated in some highland and lowland areas in Peninsular Malaysia. Leafy vegetables were represented by convolvulus (Ipomoea aquatica) and green mustard or sawi (Brassica rapa var. parachinensis), tubers and bulbs by sweet potato (Ipomoea batatas) and onion (Allium cepa), and fruity vegetables by chilly (Capsicum annuum), brinjal (Solanum melongena) and long bean (Vigna sinensis), respectively. Heavy metals from lithogenic and nonlithogenic soil fractions were studied at Cameron Highlands situated in the Pahang state and at lowland areas in Klang, Bangi, Gombak and Sepang districts in the Selangor state. The aim of the study was to investigate the availability of heavy metals and their potential uptake by vegetables in selected agricultural areas. The metals analysed were ferrum (Fe), zinc (Zn) cadmium (Cd), manganese (Mn), plumbum (Pb), copper (Cu) and chromium (Cr). Three soil samples were collected from each area and sampling was done at 1-30 cm depth. Extraction of heavy metals was carried out using sequential extraction and four fractions were produced comprising the easily leachable and ion exchange fraction, the acid reducible fraction, the oxidation organic fraction and the resistant fraction respectively. Heavy metal content in plant and soil samples were determined by atomic absorption spectrophotometry following standard methods (AOAC). Most metals were found at concentrations normally observed in vegetables grown in uncontaminated agricultural areas, with zinc (Zn) and manganese (Mn) content being highest, followed by copper (Cu), plumbum (Pb) and cadmium (Cd). However, the levels of potentially toxic metals such as Pb, Cd and Cr in the vegetables studied were found to be below the stipulated levels. Analysis of soil samples showed that the highest concentrations of heavy metals were obtained from the resistant fraction as compared to the other soil fractions. Concentration of Fe and Pb was found to be high in Sepang, whereas that of Cu was highest in Gombak and Cd levels were generally high in Sepang and Gombak. In contrast, the concentration of metals in the easily leachable and ion exchange fractions were low. Since differential uptake and accumulation of metals in the various plant parts are influenced by the availability of metals from the latter two fractions of the soils, the results indicate that availability of heavy metals to the cultivated plants (and thus, its consequent health risk to consumers) is also low. Based on the results obtained, the availability of heavy metals can be arranged as follows: Zn &gt; Mn &gt; Cd &gt; Cu &gt; Pb &gt; Fe. The agricultural soils were found to contain high levels of Fe, Mn and Zn, whilst Cd and Cr were found in very low levels, well below the critical soil levels listed for arable land

Structural Principles in Robo Activation and Auto-Inhibition

This is the author accepted manuscript. The final version is available from Elsevier (Cell Press) via the DOI in this record.Proper brain function requires high-precision neuronal expansion and wiring, processes controlled by the transmembrane Roundabout (Robo) receptor family and their Slit ligands. Despite their great importance, the molecular mechanism by which Robos’ switch from “off” to “on” states remains unclear. Here, we report a 3.6 Å crystal structure of the intact human Robo2 ectodomain (domains D1–8). We demonstrate that Robo cis dimerization via D4 is conserved through hRobo1, 2, and 3 and the C. elegans homolog SAX-3 and is essential for SAX-3 function in vivo. The structure reveals two levels of auto-inhibition that prevent premature activation: (1) cis blocking of the D4 dimerization interface and (2) trans interactions between opposing Robo receptors that fasten the D4-blocked conformation. Complementary experiments in mouse primary neurons and C. elegans support the auto-inhibition model. These results suggest that Slit stimulation primarily drives the release of Robo auto-inhibition required for dimerization and activation.ICRFIS