392 research outputs found
Scheduling over Scenarios on Two Machines
We consider scheduling problems over scenarios where the goal is to find a
single assignment of the jobs to the machines which performs well over all
possible scenarios. Each scenario is a subset of jobs that must be executed in
that scenario and all scenarios are given explicitly. The two objectives that
we consider are minimizing the maximum makespan over all scenarios and
minimizing the sum of the makespans of all scenarios. For both versions, we
give several approximation algorithms and lower bounds on their
approximability. With this research into optimization problems over scenarios,
we have opened a new and rich field of interesting problems.Comment: To appear in COCOON 2014. The final publication is available at
link.springer.co
Reexamination of a multisetting Bell inequality for qudits
The class of d-setting, d-outcome Bell inequalities proposed by Ji and
collaborators [Phys. Rev. A 78, 052103] are reexamined. For every positive
integer d > 2, we show that the corresponding non-trivial Bell inequality for
probabilities provides the maximum classical winning probability of the
Clauser-Horne-Shimony-Holt-like game with d inputs and d outputs. We also
demonstrate that the general classical upper bounds given by Ji et al. are
underestimated, which invalidates many of the corresponding correlation
inequalities presented thereof. We remedy this problem, partially, by providing
the actual classical upper bound for d less than or equal to 13 (including
non-prime values of d). We further determine that for prime value d in this
range, most of these probability and correlation inequalities are tight, i.e.,
facet-inducing for the respective classical correlation polytope. Stronger
lower and upper bounds on the quantum violation of these inequalities are
obtained. In particular, we prove that once the probability inequalities are
given, their correlation counterparts given by Ji and co-workers are no longer
relevant in terms of detecting the entanglement of a quantum state.Comment: v3: Published version (minor rewordings, typos corrected, upper
bounds in Table III improved/corrected); v2: 7 pages, 1 figure, 4 tables
(substantially revised with new results on the tightness of the correlation
inequalities included); v1: 7.5 pages, 1 figure, 4 tables (Comments are
welcome
Approximating k-Forest with Resource Augmentation: A Primal-Dual Approach
In this paper, we study the -forest problem in the model of resource
augmentation. In the -forest problem, given an edge-weighted graph ,
a parameter , and a set of demand pairs , the
objective is to construct a minimum-cost subgraph that connects at least
demands. The problem is hard to approximate---the best-known approximation
ratio is . Furthermore, -forest is as hard to
approximate as the notoriously-hard densest -subgraph problem.
While the -forest problem is hard to approximate in the worst-case, we
show that with the use of resource augmentation, we can efficiently approximate
it up to a constant factor.
First, we restate the problem in terms of the number of demands that are {\em
not} connected. In particular, the objective of the -forest problem can be
viewed as to remove at most demands and find a minimum-cost subgraph that
connects the remaining demands. We use this perspective of the problem to
explain the performance of our algorithm (in terms of the augmentation) in a
more intuitive way.
Specifically, we present a polynomial-time algorithm for the -forest
problem that, for every , removes at most demands and has
cost no more than times the cost of an optimal algorithm
that removes at most demands
A provisional database for the silicon content of foods in the United Kingdom
Si may play an important role in bone formation and connective tissue metabolism. Although biological interest in this element has recently increased, limited literature exists on the Si content of foods. To further our knowledge and understanding of the relationship between dietary Si and human health, a reliable food composition database, relevant for the UK population, is required. A total of 207 foods and beverages, commonly consumed in the UK, were analysed for Si content. Composite samples were analysed using inductively coupled plasma–optical emission spectrometry following microwave-assisted digestion with nitric acid and H2O2. The highest concentrations of Si were found in cereals and cereal products, especially less refined cereals and oat-based products. Fruit and vegetables were highly variable sources of Si with substantial amounts present in Kenyan beans, French beans, runner beans, spinach, dried fruit, bananas and red lentils, but undetectable amounts in tomatoes, oranges and onions. Of the beverages, beer, a macerated whole-grain cereal product, contained the greatest level of Si, whilst drinking water was a variable source with some mineral waters relatively high in Si. The present study provides a provisional database for the Si content of UK foods, which will allow the estimation of dietary intakes of Si in the UK population and investigation into the role of dietary Si in human health.<br /
Stable marriage and roommates problems with restricted edges: complexity and approximability
In the Stable Marriage and Roommates problems, a set of agents is given, each of them having a strictly ordered preference list over some or all of the other agents. A matching is a set of disjoint pairs of mutually acceptable agents. If any two agents mutually prefer each other to their partner, then they block the matching, otherwise, the matching is said to be stable. We investigate the complexity of finding a solution satisfying additional constraints on restricted pairs of agents. Restricted pairs can be either forced or forbidden. A stable solution must contain all of the forced pairs, while it must contain none of the forbidden pairs.
Dias et al. (2003) gave a polynomial-time algorithm to decide whether such a solution exists in the presence of restricted edges. If the answer is no, one might look for a solution close to optimal. Since optimality in this context means that the matching is stable and satisfies all constraints on restricted pairs, there are two ways of relaxing the constraints by permitting a solution to: (1) be blocked by as few as possible pairs, or (2) violate as few as possible constraints n restricted pairs.
Our main theorems prove that for the (bipartite) Stable Marriage problem, case (1) leads to View the MathML source-hardness and inapproximability results, whilst case (2) can be solved in polynomial time. For non-bipartite Stable Roommates instances, case (2) yields an View the MathML source-hard but (under some cardinality assumptions) 2-approximable problem. In the case of View the MathML source-hard problems, we also discuss polynomially solvable special cases, arising from restrictions on the lengths of the preference lists, or upper bounds on the numbers of restricted pairs
A MIQE-Compliant Real-Time PCR Assay for Aspergillus Detection
PMCID: PMC3393739This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Assessment of aerosol deposition and movement in open field conditions
Overall objective of this study was to evaluate the dispersion of aerosol plumes generated by a truck-mounted ultra low-volume (ULV) applicator and a hand-held thermal fogger under open field conditions. Experiments were also planned to determine the relative capture efficiencies of various sampling techniques in such applications. The ULV applicator was used at three travel speeds (8.5, 16.8, 24.8 km/h) and the thermal fogger at two release heights (0.6 and 1.1 m above ground) to investigate the effect of speed or release height on deposition at 6, 12, 24, and 48 m downwind. High volume air sampler (HVS), low volume air samplers (LVS), spinning cotton ribbon (CR) samplers, polypropylene green plastic cards (GC), acetate cards (AC), and water-sensitive papers (WSP) were used to collect deposits. The ULV applicator was tested with water and oil sprays while the thermal fogger was tested with the latter tracer only. Using water- and oil-based tracers, all deposition targets were analyzed by fluorometry. Results showed decreased tracer deposition with increase in sampling distance. Overall, travel speed affected deposition at the near sample locations only, but in most sample locations, normalized deposits were comparable at all speeds. Spray release height did not affect deposition of active samplers but had significant effect on deposition of passive samplers at 6 m location only. Overall, the higher release height resulted in more deposition in most downwind locations. There were good correlations between depositions on active and passive samplers. The HVS, CR, GC, and AC samplers were effective in sampling aerosol plume dispersion under open field conditions. The paper includes relationships among capture efficiencies of various samplers.Keywords: ULV applicator, thermal fogger, deposition samplers, Yellow 131SC dye, Pyranine 10G, fluorometr
Bipolar resistive switching and memristive properties of hydrothermally synthesized TiO2 nanorod array: Effect of growth temperature
The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.matdes.2018.04.046 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/In the present work, the hydrothermal approach is employed to develop 1D-TiO2 nanorod array memristive devices and the effect of hydrothermal growth temperature on TiO2 memristive devices is studied. X-ray diffraction (XRD) analysis suggested that the rutile phase is dominant in the developed TiO2 nanorod array. Field emission scanning electron microscopy (FESEM) images show well adherent and pinhole free one dimensional (1D) TiO2 nanorods. The presence of titanium and oxygen in all the samples was confirmed by energy dispersive X-ray spectroscopy (EDS). Furthermore, growth of the 1D TiO2 nanorods depends on the growth temperature and uniform growth is observed at the higher growth temperatures. The well-known memristive hysteresis loop is observed in the TiO2 nanorod thin films. Furthermore, resistive switching voltages, the shape of I-V loops and (non)rectifying behavior changed as the growth temperature varied from 140 °C to 170 °C. The biological synapse properties such as paired-pulse facilitation and short-term depression are observed in some devices. The detailed electrical characterizations suggested that the developed devices show doubled valued charge-magnetic flux characteristic and charge transportation is due to the Ohmic and space charge limited current.Funding from School of Nanoscience and Biotechnology, Shivaji University, Kolhapu
Conflict, Crisis, and Abuse in Dharavi, Mumbai: Experiences from Six Years at a Centre for Vulnerable Women and Children
Nayreen Daruwalla and colleagues describe the Centre for Vulnerable Women and Children, which serves clients coping with crisis and violence in the urban setting of Dharavi, Mumbai
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