19 research outputs found

    Родовище високомінералізованої борної гідрокарбонатної натрієвої мінеральної води Пасіка на Закарпатті та особливості її біологічної дії

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    Дана характеристика месторождений и биологических свойств борных гидрокарбонатных натриевых вод Закарпатья.It is done the characteristics of layers and biological properties of high mineralized boric hydrocarbonate sodium mineral waters on Zakarpattya

    Towards a better solution to the shortest common supersequence problem: the deposition and reduction algorithm

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    BACKGROUND: The problem of finding a Shortest Common Supersequence (SCS) of a set of sequences is an important problem with applications in many areas. It is a key problem in biological sequences analysis. The SCS problem is well-known to be NP-complete. Many heuristic algorithms have been proposed. Some heuristics work well on a few long sequences (as in sequence comparison applications); others work well on many short sequences (as in oligo-array synthesis). Unfortunately, most do not work well on large SCS instances where there are many, long sequences. RESULTS: In this paper, we present a Deposition and Reduction (DR) algorithm for solving large SCS instances of biological sequences. There are two processes in our DR algorithm: deposition process, and reduction process. The deposition process is responsible for generating a small set of common supersequences; and the reduction process shortens these common supersequences by removing some characters while preserving the common supersequence property. Our evaluation on simulated data and real DNA and protein sequences show that our algorithm consistently produces the best results compared to many well-known heuristic algorithms, and especially on large instances. CONCLUSION: Our DR algorithm provides a partial answer to the open problem of designing efficient heuristic algorithm for SCS problem on many long sequences. Our algorithm has a bounded approximation ratio. The algorithm is efficient, both in running time and space complexity and our evaluation shows that it is practical even for SCS problems on many long sequences

    Polynomial-time approximation schemes for scheduling problems with time lags

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    We identify two classes of machine scheduling problems with time lags that possess Polynomial-Time Approximation Schemes (PTASs). These classes together, one for minimizing makespan and one for minimizing total completion time, include many well-studied time lag scheduling problems. The running times of these approximation schemes are polynomial in the number of jobs, but exponential in the number of machines and the ratio between the largest time lag and the smallest positive operation time. These classes constitute the first PTAS results for scheduling problems with time lags

    Integer preemptive scheduling on parallel machines

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    We consider preemptive machine scheduling problems on identical parallel machines. It is shown that every such problem with chain-like precedence constraints, release dates and a regular unit-concave objective function (e.g. total weighted tardiness and total weighted number of late jobs) has the following integer preemption property: for any problem instance with integral input data there exists an optimal schedule where all interruptions (as well as starting and completion times of jobs) occur at integer time points

    Offline thermal-desorption proton-transfer-reaction mass spectrometry to study composition of organic aerosol

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    We present a novel approach to study the organic composition of aerosol filter samples using thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) in the laboratory. The method is tested and validated based on the comparison with in situ TD-PTR-MS measurements. In general, we observe correspondence within the levels of uncertainty between in situ and offline TD-PTR-MS measurements for compounds desorbing at temperatures above 100. °C and for quartz fiber filters that were sampled for more than one day. Positive sampling artifacts (50-80%, with respect to the in situ measurements) from adsorption of semivolatile organic gas phase compounds are apparent on filters sampled for one day. Detailed chemical analysis shows that these positive sampling artifacts are likely caused by primary emissions that have not been strongly oxidized. Negative sampling artifacts (7-35%, with respect to the in situ measurements) are observed for most filters sampled for two and three days, and potentially caused by incomplete desorption of aerosols (in particular, nitrogen-containing organics) from the filters during the offline measurements and chemical reactions on the filters

    Offline thermal-desorption proton-transfer-reaction mass spectrometry to study composition of organic aerosol

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    We present a novel approach to study the organic composition of aerosol filter samples using thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) in the laboratory. The method is tested and validated based on the comparison with in situ TD-PTR-MS measurements. In general, we observe correspondence within the levels of uncertainty between in situ and offline TD-PTR-MS measurements for compounds desorbing at temperatures above 100. °C and for quartz fiber filters that were sampled for more than one day. Positive sampling artifacts (50-80%, with respect to the in situ measurements) from adsorption of semivolatile organic gas phase compounds are apparent on filters sampled for one day. Detailed chemical analysis shows that these positive sampling artifacts are likely caused by primary emissions that have not been strongly oxidized. Negative sampling artifacts (7-35%, with respect to the in situ measurements) are observed for most filters sampled for two and three days, and potentially caused by incomplete desorption of aerosols (in particular, nitrogen-containing organics) from the filters during the offline measurements and chemical reactions on the filters

    Active Atmosphere-Ecosystem exchange of the vast majority of detected volatile organic compounds

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    Numerous volatile organic compounds (VOCs) exist in Earth’s atmosphere, most of which originate from biogenic emissions. Despite VOCs’ critical role in tropospheric chemistry, studies for evaluating their atmosphere-ecosystem exchange (emission and deposition) have been limited to a few dominant compounds owing to a lack of appropriate measurement techniques. Using a high–mass resolution proton transfer reaction–time of flight–mass spectrometer and an absolute value eddy-covariance method, we directly measured 186 organic ions with net deposition, and 494 that have bidirectional flux. This observation of active atmosphere-ecosystem exchange of the vast majority of detected VOCs poses a challenge to current emission, air quality, and global climate models, which do not account for this extremely large range of compounds. This observation also provides new insight for understanding the atmospheric VOC budget

    A Probabilistic Beam Search Approach to the Shortest Common Supersequence Problem ⋆

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    Abstract. The Shortest Common Supersequence Problem (SCSP) is a well-known hard combinatorial optimization problem that formalizes many real world problems. This paper presents a novel randomized search strategy, called probabilistic beam search (PBS), based on the hybridization between beam search and greedy constructive heuristics. PBS is competitive (and sometimes better than) previous state-of-the-art algorithms for solving the SCSP. The paper describes PBS and provides an experimental analysis (including comparisons with previous approaches) that demonstrate its usefulness.
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