1,448 research outputs found
A Hybrid System for Well Test Analysis
Petroleum well test analysis is a tool for estimating the average properties of the reservoir rock. It is a classic example of an inverse problem. Visual examination of the pressure response of the reservoir to an induced flow rate change at a well allows the experienced analyst to determine the most appropriate model from a library of generalized analytical solutions. Rock properties are determined by finding the model parameters that best fit the observed data. This paper describes a framework for hybrid network to assist the analyst in selecting the appropriate model and determining the solution. The hybrid network design offers significant advantages by reducing training time and allowing incorporation of both symbolic and numeric data. The network structure is described and the advantages and disadvantages compared to previous approaches are discusse
Parallel solution of high-order numerical schemes for solving incompressible flows
A new parallel numerical scheme for solving incompressible steady-state flows is presented. The algorithm uses a finite-difference approach to solving the Navier-Stokes equations. The algorithms are scalable and expandable. They may be used with only two processors or with as many processors as are available. The code is general and expandable. Any size grid may be used. Four processors of the NASA LeRC Hypercluster were used to solve for steady-state flow in a driven square cavity. The Hypercluster was configured in a distributed-memory, hypercube-like architecture. By using a 50-by-50 finite-difference solution grid, an efficiency of 74 percent (a speedup of 2.96) was obtained
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Influence of Acidic pH on Hydrogen and Acetate Production by an Electrosynthetic Microbiome
Production of hydrogen and organic compounds by an electrosynthetic microbiome using electrodes and carbon dioxide as sole electron donor and carbon source, respectively, was examined after exposure to acidic pH (∼5). Hydrogen production by biocathodes poised at −600 mV vs. SHE increased>100-fold and acetate production ceased at acidic pH, but ∼5–15 mM (catholyte volume)/day acetate and>1,000 mM/day hydrogen were attained at pH ∼6.5 following repeated exposure to acidic pH. Cyclic voltammetry revealed a 250 mV decrease in hydrogen overpotential and a maximum current density of 12.2 mA/cm2 at −765 mV (0.065 mA/cm2 sterile control at −800 mV) by the Acetobacterium-dominated community. Supplying −800 mV to the microbiome after repeated exposure to acidic pH resulted in up to 2.6 kg/m3/day hydrogen (≈2.6 gallons gasoline equivalent), 0.7 kg/m3/day formate, and 3.1 kg/m3/day acetate ( = 4.7 kg CO2 captured).</p
(Pyridin-4-yl)methyl N′-(3-phenylallylidene)hydrazinecarbodithioate.
In the title compound, C16H15N3S2, the central C2N2S2 residue is planar (r.m.s. deviation = 0.045 Å) and the pyridyl and benzene rings are inclined and approximately coplanar to this plane, respectively [dihedral angles = 72.85 (9) and 10.73 (9)°], so that, overall, the molecule adopts an L-shape. The conformation about each of the N=C [1.290 (3) Å] and C=C [1.340 (3) Å] bonds is E. Supramolecular chains along [1-10] are stabilized by N—H(...)N(pyridine) hydrogen bonding and these are connected into a double layer that stacks along the c-axis direction by C—H(...)π(pyridine) interactions
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Large-scale discovery of enhancers from human heart tissue.
Development and function of the human heart depend on the dynamic control of tissue-specific gene expression by distant-acting transcriptional enhancers. To generate an accurate genome-wide map of human heart enhancers, we used an epigenomic enhancer discovery approach and identified ∼6,200 candidate enhancer sequences directly from fetal and adult human heart tissue. Consistent with their predicted function, these elements were markedly enriched near genes implicated in heart development, function and disease. To further validate their in vivo enhancer activity, we tested 65 of these human sequences in a transgenic mouse enhancer assay and observed that 43 (66%) drove reproducible reporter gene expression in the heart. These results support the discovery of a genome-wide set of noncoding sequences highly enriched in human heart enhancers that is likely to facilitate downstream studies of the role of enhancers in development and pathological conditions of the heart
Effects of different feeding systems on growth, fat accumulation and semen quality of Merino-type sheep
In South Africa, supplemental feeding is provided to improve the condition of breeding livestock before the animals are sold by the stud breeders to commercial farmers. This study aimed to evaluate the effects of different ram rearing systems on growth, fat accumulation and semen quality of Döhne Merino (DM), Merino (M) and South African Mutton Merino (SAMM) rams intended for breeding. The ram lambs were stratified according to weight and randomly allocated to one of three treatments, namely an extensive feeding treatment (ET), an extensive-intensive feeding treatment (EIT), and an intensive feeding treatment (IT). Rams in ET grazed for 200 days. Rams in EIT grazed for 73 days, followed by a concentrate diet for an additional 60 days. Rams in IT were fed the concentrate diet for 70 days. Scrotal neck fat was significantly less in IT rams compared with ET and EIT rams. Döhne Merino and M rams in EIT deposited significantly more scrotal fat than DM and M rams in ET. No adverse testicular pathology or differences in semen quality were observed. Regression analyses of pooled data showed extreme functional values for subcutaneous fat and total scrotal fat weight, which, when exceeded, may result in decreased semen volume, percentage normal spermatozoa and mass motility of spermatozoa. Sheep breeders should be cautious when feeding ram lambs in extensive-intensive systems for extended periods since this may affect semen quality adversely.Vrede Veld Ram Club.https://www.sasas.co.za/resources/sa-journal-animal-scienceAnimal and Wildlife Science
VIP and PACAP receptors (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Vasoactive Intestinal Peptide Receptors [64, 65]) are activated by the endogenous peptides VIP, PACAP-38, PACAP-27, peptide histidine isoleucineamide (PHI), peptide histidine methionineamide (PHM) and peptide histidine valine (PHV). VPAC1 and VPAC2 receptors display comparable affinity for the PACAP peptides, PACAP-27 and PACAP-38, and VIP, whereas PACAP-27 and PACAP-38 are >100 fold more potent than VIP as agonists of most isoforms of the PAC1 receptor. However, one splice variant of the human PAC1 receptor has been reported to respond to PACAP-38, PACAP-27 and VIP with comparable affinity [29]. PG 99-465 [115] has been used as a selective VPAC2 receptor antagonist in a number of physiological studies, but has been reported to have significant activity at VPAC1 and PAC1 receptors [35]. The selective PAC1 receptor agonist maxadilan, was extracted from the salivary glands of sand flies (Lutzomyia longipalpis) and has no sequence homology to VIP or the PACAP peptides [116]. Two deletion variants of maxadilan, M65 [180] and Max.d.4 [117] have been reported to be PAC1 receptor antagonists, but these peptides have not been extensively characterised
VIP and PACAP receptors in GtoPdb v.2023.1
Vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating peptide (PACAP) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Vasoactive Intestinal Peptide Receptors [65, 66]) are activated by the endogenous peptides VIP, PACAP-38, PACAP-27, peptide histidine isoleucineamide (PHI), peptide histidine methionineamide (PHM) and peptide histidine valine (PHV). VPAC1 and VPAC2 receptors display comparable affinity for the PACAP peptides, PACAP-27 and PACAP-38, and VIP, whereas PACAP-27 and PACAP-38 are >100 fold more potent than VIP as agonists of most isoforms of the PAC1 receptor. However, one splice variant of the human PAC1 receptor has been reported to respond to PACAP-38, PACAP-27 and VIP with comparable affinity [30]. PG 99-465 [117] has been used as a selective VPAC2 receptor antagonist in a number of physiological studies, but has been reported to have significant activity at VPAC1 and PAC1 receptors [36]. The selective PAC1 receptor agonist maxadilan, was extracted from the salivary glands of sand flies (Lutzomyia longipalpis) and has no sequence homology to VIP or the PACAP peptides [118]. Two deletion variants of maxadilan, M65 [183] and Max.d.4 [119] have been reported to be PAC1 receptor antagonists, but these peptides have not been extensively characterised
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