A different approach for predicting H(2)S((g)) emission rates in gravity sewers

All detrimental phenomena (mal odors, metal corrosion, concrete disintegration, health hazard) associated with hydrogen sulfide in gravity sewers depend on the rate of H(2)S emission from the aqueous phase to the gas phase of the pipe. In this paper a different approach for predicting H(2)S((g)) emission rates from gravity sewers is presented, using concepts adapted from mixing theory. The mean velocity gradient (G=gamma SV/micro; S is the slope, V the mean velocity), representing mixing conditions in gravity flow, was used to quantify the rate of H(2)S((g)) emission in part-full gravity sewers. Based on this approach an emission equation was developed. The equation was verified and calibrated by performing 20 experiments in a 27-m gravity-flow experimental-sewer (D=0.16 m) at various hydraulic conditions. Results indicate a clear dependency of the sulfide stripping-rate on G(1) (R(2)=0.94) with the following overall emission equation: where S(T) is the total sulfide concentration in the aqueous phase, mg/L; w the flow surface width, m; A(cs) the cross-sectional area, m(2); T the temperature, degrees C; K(H) the Henry's constant, molL(-1)atm(-1); and P(pH2S) the partial pressure of H(2)S((g)) in the sewer atmosphere, atm.     

Querying Semistructured Heterogeneous Information

Semistructured data has no absolute schema fixed in advance and its structure may be irregular or incomplete. Such data commonly arises in sources that do not impose a rigid structure (such as the World-Wide Web) and when data is combined from several heterogeneous sources. Data models and query languages designed for well structured data are inappropriate in such environments. Starting with a lightweight object model adopted for the TSIMMIS project at Stanford, in this paper we describe a query language and object repository designed specifically for semistructured data. Our language provides meaningful query results in cases where conventional models and languages do not: when some data is absent, when data does not have regular structure, when similar concepts are represented using different types, when heterogeneous sets are present, and when object structure is not fully known. This paper motivates the key concepts behind our approach, describes the language through a series of examples (a complete semantics is available in an accompanying technical report [23]), and describes the basic architecture and query processing strategy of the lightweight object repository we have developed.     

Genome-Wide Association Study in Bread Wheat Identifies Genomic Regions Associated with Grain Yield and Quality under Contrasting Water Availability

The objectives of this study were to identify genetic loci in the bread wheat genome that would influence yield stability and quality under water stress, and to identify accessions that can be recommended for cultivation in dry and hot regions. We performed a genome-wide association study (GWAS) using a panel of 232 wheat accessions spanning diverse ecogeographic regions. Plants were evaluated in the Israeli Northern Negev, under two environments: water-limited (D; 250 mm) and well-watered (W; 450 mm) conditions; they were genotyped with ~71,500 SNPs derived from exome capture sequencing. Of the 14 phenotypic traits evaluated, 12 had significantly lower values under D compared to W conditions, while the values for two traits were higher under D. High heritability (H² = 0.5–0.9) was observed for grain yield, spike weight, number of grains per spike, peduncle length, and plant height. Days to heading and grain yield could be partitioned based on accession origins. GWAS identified 154 marker-trait associations (MTAs) for yield and quality-related traits, 82 under D and 72 under W, and identified potential candidate genes. We identified 24 accessions showing high and/or stable yields under D conditions that can be recommended for cultivation in regions under the threat of global climate change.     

Performance of diode-end-pumped Cr, Nd:YAG self-Q-switched and Nd:YAG/Cr:YAG diffusion bonded lasers

Self-passively Q-switching of a diode-pumped Cr,Nd:YAG, where the Cr⁴⁺ is used as a saturable absorber for the 1064 nm laser emission is reported. The maximum average output power was obtained using an output coupler of R=86%. The self-Q-switched diode pumped laser yielded 1.86-W average output power with low threshold pumping power (≈1.7-W), average slope efficiency of ≈34%, pulse duration of about 14–16 ns, and modulation frequency ranging from 2.4 to 73 kHz, depending on the input pumping power. These results are the highest reported for self-Q-switched lasers. Higher slope efficiency (42%) and shorter Q-switched pulses were obtained for a Q-switched Nd:YAG/Cr⁴⁺:YAG diffusion bonded laser. A comparison of the codoped Cr,Nd:YAG laser performance, with that of a diffusion bonded laser is reported and analyzed.     

The structure and dynamics of worry: theory, measurement, and cross-national replications

This article presents a comprehensive conceptualization of the structure of worry and the relation of worry to mental health and well-being. It is assumed that worries have two facets, namely, the object of a worry (e.g., self, close others, society, the world) and the domain of a worry (the field of life with which it is concerned). The object of a worry is presumed to be more important than its domain in determining the impact of worries on mental health. Only worries concerned with self and close others (micro worries) are expected to be related to poor mental health, whereas worries about society or the entire world (macro worries) are expected to be positively related to mental health. An instrument is introduced to study worries in accordance with the proposed structure. Its validity is tested by two confirmatory techniques (similarity structure analysis and confirmatory factor analysis) in samples from Israel, West Germany, and (the former) East Germany. Worry scores are also related to five mental health indicators. Results show that across samples micro and macro worries can validly be distinguished. Micro worries are strongly related to poor mental health, whereas macro worries are unrelated to mental health or relate marginally to positive well-being.     

A General Framework for Automatic Termination Analysis of Logic Programs

This paper describes a general framework for automatic termination analysis of logic programs, where we understand by “termination” the finiteness of the LD-tree constructed for the program and a given query. A general property of mappings from a certain subset of the branches of an infinite LD-tree into a finite set is proved. From this result several termination theorems are derived, by using different finite sets. The first two are formulated for the predicate dependency and atom dependency graphs. Then a general result for the case of the query-mapping pairs relevant to a program is proved (cf. [29, 21]). The correctness of the TermiLog system described in [22] follows from it. In this system it is not possible to prove termination for programs involving arithmetic predicates, since the usual order for the integers is not well-founded. A new method, which can be easily incorporated in TermiLog or similar systems, is presented, which makes it possible to prove termination for programs involving arithmetic predicates. It is based on combining a finite abstraction of the integers with the technique of the query-mapping pairs, and is essentially capable of dividing a termination proof into several cases, such that a simple termination function suffices for each case. Finally several possible extensions are outlined. Received: August 30, 1999     

Pumping Current Noise in Ballistic Nanostructures: Acoustoelectric Current in a Point Contact

We consider current noise in a non-biased ballistic nanostructure irradiated by an AC field, which is assumed to be a stationary random process to imitate time averaging in the experiment. The AC field creates a current, which contains DC and AC components, the latter vanishing after time averaging. Correspondingly, the correlator describing current noise has two contributions. The first contribution to it is responsible for the fluctuations of the DC current. These fluctuations happen because of electron inelastic transitions between scattering states. Transitions agitated by the thermal bath lead to a thermal noise spectrum, which disappears at zero temperature; its magnitude is renormalized compared to equilibrium. Transitions initiated by the AC field lead to a noise spectrum, which is a convolution of the thermal one and that of the AC field. The magnitude of this noise is proportional to the power of the AC field and is finite at zero temperature. The second contribution to the noise correlator is due to fluctuations of the AC current. This noise does not depend on temperature, and its spectrum reproduces that of the AC field.     

Blind deconvolution of images using optimal sparse representations.

The relative Newton algorithm, previously proposed for quasi-maximum likelihood blind source separation and blind deconvolution of one-dimensional signals is generalized for blind deconvolution of images. Smooth approximation of the absolute value is used as the nonlinear term for sparse sources. In addition, we propose a method of sparsification, which allows blind deconvolution of arbitrary sources, and show how to find optimal sparsifying transformations by supervised learning.     

Concurrency and Trie Hashing

Summary The Trie Hashing (TH), defined by Litwin, is one of the fastest access methods for dynamic and ordered files. The hashing function is defined in terms of a trie, which is basically a binary tree where a character string is associated implicitly with each node. This string is compared with a prefix of the given key in the search process, and depending on the result either the left or the right child is chosen as the next node to visit. The leaf nodes point to buckets which contain the records. The buckets are on a disk, whereas the trie itself is in the core memory. In this paper we consider concurrent execution of the TH operations. In addition to the usual search, insertion and deletion operations, we also include range queries among the concurrent operations. Our algorithm locks only leaf nodes and at most two nodes need to be locked simultaneously by any operation regardless of the number of buckets being accessed. The modification required in the basic data structure in order to accommodate concurrent operations is very minor.The work of this author was supported in part by grant 2545-2-87 from the Israeli National Council for Research and DevelopmentThis research was done while visiting I.N.R.I.A., and is supported in part by the Natural Sciences and Engineering Research Council of Canada, Individual Operating Grant A-3182     

On the expressiveness of probabilistic XML models

Various known models of probabilistic XML can be represented as instantiations of the abstract notion of p-documents. In addition to ordinary nodes, p-documents have distributional nodes that specify the possible worlds and their probabilistic distribution. Particular families of p-documents are determined by the types of distributional nodes that can be used as well as by the structural constraints on the placement of those nodes in a p-document. Some of the resulting families provide natural extensions and combinations of previously studied probabilistic XML models. The focus of the paper is on the expressive power of families of p-documents. In particular, two main issues are studied. The first is the ability to (efficiently) translate a given p-document of one family into another family. The second is closure under updates, namely, the ability to (efficiently) represent the result of updating the instances of a p-document of a given family as another p-document of that family. For both issues, we distinguish two variants corresponding to value-based and object-based semantics of p-documents.