511,279 research outputs found
Turbulent MHD channel flows under streamwise magnetic field
No full textA streamwise magnetic field leads to turbulent drag reduction in channel flow of a conducting liquid due to the selective Joule damping of certain flow structures. Near the walls, the turbulent mean velocity profile retains the logarithmic layer but the von Karman constant decreases with increasing magnetic field strength. In the outer region, the flow is characterized by persistent streaky structures of large streamwise extent, which lead to a rather flat mean velocity profile. In addition, the streamwise velocity fluctuations develop a pronounced second peak upon increasing the magnetic induction as well as a second logarithmic layer that increases in steepness
String field theoryะ Time evolution and T-duality
No full textThe time evolution operator of quantum field theory (Schrödinger functional) can be written in terms of particles moving on S(^1)/Z(_2-). By deriving the 'gluing property’ which joins two propagators across fixed time surfaces, we show that the Feynman diagram expansion of the free Schrödinger functional is determined once we know the field propagator. We generalise the gluing property to a new method of sewing string field propagators and construct the string field Schrödinger functional in terms of strings moving on S(^1)/Z(_2-). Timelike T-duality in string theory then appears as a large/small time symmetry of string field theory with an exchange of boundary states and string backgrounds. All of our arguments apply equally to the open and closed string. The addition of interactions to quantum field theory bring no complication to our arguments, but modifications are required when the interaction is non-local. As application of these methods we construct the interacting string field vacuum wave functional using knowledge of the vacuum expectation values it must generate
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
Smoking expectancy mediates the conditioned responses to arbitrary smoking cues
No full textSmokers' responses to smoking cues may be the result of a classical conditioning process. There is evidence that classical conditioning may not proceed in human subjects unless subjects are consciously aware of the stimulus (CS)-reinforcer (UCS) contingencies. In two experiments the role of CS[left right arrow]UCS contingency awareness in the expression of conditioned responses (craving, salivation, and skin conductance) was studied. A discriminative classical conditioning paradigm was used during which subjects were presented with one stimulus (the CS+) always paired with cigarette smoking (the UCS) and another (the CS-) never paired with cigarette smoking. Half of the subjects were given instructions to discover the CS[left right arrow]UCS contingencies (group 'aware', AWR), whereas the other half were not (group 'unaware', UWR). In experiment 1, all subjects responded to the CS+ with increased cigarette craving relative to the CS-; this effect was more pronounced in the AWR group compared to the UWR group. A lower amount of salivation in response to the CS+ compared to the CS- was found in the UWR group. These between-group differences were interpreted as a consequence of the enhanced expectancies of smoking in the presence of CS+ in group AWR compared to group UWR. In experiment 2, the observed craving responses to CS+ and CS- were consistent with those seen in experiment 1, but no discriminative salivary response to the stimuli was found. When, after conditioning training, subjects' expectancies of smoking were removed by instructions, and their responses to CS+ and CS- were again measured, the discriminative craving response to CS+ and CS- was eliminated and all subjects demonstrated a lower amount of salivation in response to the CS+ compared to the CS-. These data suggest that presentation of arbitrary cues previously paired with cigarette smoking can elicit CRs and that facilitation of awareness of the CS[left right arrow]UCS contingency by instructions can potentiate craving CRs. In addition, these data suggest that craving CRs can be eliminated, whereas compensatory CRs can be facilitated, when cigarette expectancy is removed with instructions
Microbial enrichment culture responsible for the complete oxidative biodegradation of 3‑Amino-1,2,4-triazol-5-one (ATO), the reduced daughter product of the insensitive munitions compound 3‑Nitro-1,2,4-triazol-5-one (NTO)
No full text3-Nitro-1,2,4-triazol-5-one (NTO) is one of the main ingredients of many insensitive munitions, which are being used as replacements for conventional explosives. As its use becomes widespread, more research is needed to assess its environmental fate. Previous studies have shown that NTO is biologically reduced to 3-amino-1,2,4-triazol-5-one (ATO). However, the final degradation products of ATO are still unknown. We have studied the aerobic degradation of ATO by enrichment cultures derived from the soil. After multiple transfers, ATO degradation was monitored in closed bottles through measurements of inorganic carbon and nitrogen species. The results indicate that the members of the enrichment culture utilize ATO as the sole source of carbon and nitrogen. As ATO was mineralized to CO₂, N₂, and NH₄⁺, microbial growth was observed in the culture. Co-substrates addition did not increase the ATO degradation rate. Quantitative polymerase chain reaction analysis revealed that the organisms that enriched using ATO as carbon and nitrogen source were Terrimonas spp., Ramlibacter-related spp., Mesorhizobium spp., Hydrogenophaga spp., Ralstonia spp., Pseudomonas spp., Ectothiorhodospiraceae, and Sphingopyxis. This is the first study to report the complete mineralization of ATO by soil microorganisms, expanding our understanding of natural attenuation and bioremediation of the explosive NTO.Journal ArticleFinal article publishe
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Sense-T: Sensor smart irrigation
No full textThe Sense-T Sensor-Smart Irrigation app predicts daily soil-water in the infield spatial zones using FAO-56. The irrigation requirement is determined in each zone from the difference between the predicted soil-water and field capacity. Incorporation of a biophysical crop production model enhances prediction capability for crop yield and impacts of irrigation management decisions on production and water use efficiency over the prediction horizon.Crop production models can be calibrated to reflect field conditions using machine vision and imagery from infield or remote sensors. This section presents an investigation of crop production models for incorporation into the app for production prediction
The Clinical Utility of Magnetic Resonance Imaging According to Field Strength, Specifically Addressing the Breadth of Current State-of-the-Art Systems, Which Include 0.55 T, 1.5 T, 3 T, and 7 T.
No full textABSTRACT
This review provides a balanced perspective regarding the clinical utility of magnetic resonance systems across the range of field strengths for which current state-of-the-art units exist (0.55 T, 1.5 T, 3 T, and 7 T). Guidance regarding this issue is critical to appropriate purchasing, usage, and further dissemination of this important imaging modality, both in the industrial world and in developing nations. The review serves to provide an important update, although to a large extent this information has never previously been openly presented. In that sense, it serves also as a position paper, with statements and recommendations as appropriate
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