292 research outputs found

    An O∗(1.0821n)O^*(1.0821^n)-Time Algorithm for Computing Maximum Independent Set in Graphs with Bounded Degree 3

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    We give an O∗(1.0821n)O^*(1.0821^n)-time, polynomial space algorithm for computing Maximum Independent Set in graphs with bounded degree 3. This improves all the previous running time bounds known for the problem

    A Quantum Approximation Scheme for k-Means

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    We give a quantum approximation scheme (i.e., (1+ε)(1 + \varepsilon)-approximation for every ε>0\varepsilon > 0) for the classical kk-means clustering problem in the QRAM model with a running time that has only polylogarithmic dependence on the number of data points. More specifically, given a dataset VV with NN points in Rd\mathbb{R}^d stored in QRAM data structure, our quantum algorithm runs in time O~(2O~(kε)η2d)\tilde{O} \left( 2^{\tilde{O}(\frac{k}{\varepsilon})} \eta^2 d\right) and with high probability outputs a set CC of kk centers such that cost(V,C)≤(1+ε)⋅cost(V,COPT)cost(V, C) \leq (1+\varepsilon) \cdot cost(V, C_{OPT}). Here COPTC_{OPT} denotes the optimal kk-centers, cost(.)cost(.) denotes the standard kk-means cost function (i.e., the sum of the squared distance of points to the closest center), and η\eta is the aspect ratio (i.e., the ratio of maximum distance to minimum distance). This is the first quantum algorithm with a polylogarithmic running time that gives a provable approximation guarantee of (1+ε)(1+\varepsilon) for the kk-means problem. Also, unlike previous works on unsupervised learning, our quantum algorithm does not require quantum linear algebra subroutines and has a running time independent of parameters (e.g., condition number) that appear in such procedures

    Functionalized Transparent Surfaces with Enhanced Self-Cleaning against Ink Aerosol Contamination

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    During operation of a standard commercial inkjet printer, suspended ink particles form an ink aerosol inside the printing chamber that can cause serious malfunctions, including contamination of the transparent window of the printhead position calibration optical sensors. In this work, transparent conducting film (TCF) and surface functionalization through self-assembled monolayer (SAM) are proposed and investigated to repel ink aerosol deposition on a transparent surface and to reduce its adverse effects. The results show that the combination of the Joule heating effect induced by applying an electrical current to the TCF and hydrophobic property of the SAM reduces transmittance loss from an average of 10% to less than 1.5%. Correspondingly, the area of the surface covered by ink decreases from 45.62% ± 6.15% to 1.71% ± 0.25%. The preliminary results are obtained with glass substrates and subsequently extended to the plastic window of a commercial inkjet printer calibration sensor, thus demonstrating the potential of the proposed approach to reduce aerosol contamination in real applications.Peer ReviewedPostprint (author's final draft

    On the Distribution of the Fourier Spectrum of Halfspaces

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    Bourgain showed that any noise stable Boolean function ff can be well-approximated by a junta. In this note we give an exponential sharpening of the parameters of Bourgain's result under the additional assumption that ff is a halfspace

    Toxicity of extracts derived from different parts of cassava plant, Manihot esculenta Crantz to four major coleopteran pests of stored-products: Poster

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    Fumigant toxicity of insecticidal principles extracted from tuber rind, fresh leaf, fresh leaf with petiole, and dried leaf of cassava (var. M4) was studied against four major stored-product insect pests viz. Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Tribolium castaneum (Herbst) and Callosobruchus chinensis (L.) under laboratory conditions (28±2ºC, Rh. 75±5%). Mortality of the test insects varied with respect to extracts collected from different parts of the plant, and time of exposure. Extract collected from cassava rind recorded the highest toxicity. Callosobruchus chinensis was highly susceptible and showed immediate knockdown effect to the active principles extracted from tuber rind, fresh leaf, fresh leaf with petiole, twig and semi-dried leaf. The extract collected from various parts of plant caused 100% mortality of R. dominica at 1 hour after treatment (HAT), but the same collected from tuber and dried leaves did not show any toxic effect. Mortality of S. oryzae was 100% at 1 HAT with tuber rind extract, but no response was observed from the extract collected from semi-dried leaf, twig, and leaf with petiole. No fumigant action was observed in all the four coleopteran pests exposed to the extract collected from dried leaves. The study revealed that fresh leaf and tuber rind are good sources for the extraction of biofumigant against major coleopteran pests, however dried leaves are unfit for same purpose.Fumigant toxicity of insecticidal principles extracted from tuber rind, fresh leaf, fresh leaf with petiole, and dried leaf of cassava (var. M4) was studied against four major stored-product insect pests viz. Sitophilus oryzae (L.), Rhyzopertha dominica (F.), Tribolium castaneum (Herbst) and Callosobruchus chinensis (L.) under laboratory conditions (28±2ºC, Rh. 75±5%). Mortality of the test insects varied with respect to extracts collected from different parts of the plant, and time of exposure. Extract collected from cassava rind recorded the highest toxicity. Callosobruchus chinensis was highly susceptible and showed immediate knockdown effect to the active principles extracted from tuber rind, fresh leaf, fresh leaf with petiole, twig and semi-dried leaf. The extract collected from various parts of plant caused 100% mortality of R. dominica at 1 hour after treatment (HAT), but the same collected from tuber and dried leaves did not show any toxic effect. Mortality of S. oryzae was 100% at 1 HAT with tuber rind extract, but no response was observed from the extract collected from semi-dried leaf, twig, and leaf with petiole. No fumigant action was observed in all the four coleopteran pests exposed to the extract collected from dried leaves. The study revealed that fresh leaf and tuber rind are good sources for the extraction of biofumigant against major coleopteran pests, however dried leaves are unfit for same purpose
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