Low flow hydraulics in alluvial channels

The investigation of the low flow condition has become important in recent years as a means of determining critical levels of water pollution, aquatic habitat and instream flow needs. To assess these critical conditions, it is necessary to predict the hydraulic response of a river system to a given low flow discharge. Conventional flow models, however, are often inaccurate at low discharges due to the geometric and hydraulic channel features peculiar to these flow conditions. The dominant channel feature at low stages is the pool-riffle sequence, where pools are distinguished by deep, slow moving water and riffles by shallow, relatively rapid moving flow. Conventional flow models have difficulty effectively representing the highly nonprismatic channel geometry, the rapidly changing flow hydraulics, and the dominating influence of flow resistance characteristic of pool-riffle sequences. In this research, a one-dimensional mathematical model has been developed to simulate accurately channel characteristics under low flow conditions. For a given steady discharge, channel geometry, and channel bed particle size distribution, the model predicts the flow depth, the mean velocity, and the flow resistance. Energy losses are assumed to result from flow resistance, as well as from local losses generated by the contractions and expansions occurring through the pool-riffle sequence. The model has been verified using field data, as well as laboratory data collected in conjunction with the project.U.S. Department of the InteriorU.S. Geological SurveyOpe

Formation and structural chemistry of the unusual cyanide-bridged dinuclear species [Ru-2(NN)(2)(CN)(7)](3-)(NN=2,2 '-bipyridine or 1,10-phenanthroline)

Crystallisation of simple cyanoruthenate complex anions [Ru(NN)(CN)(4)](2) (NN = 2,2'-bipyridine or 1,10-phenanthroline) in the presence of Lewis-acidic cations such as Ln(III) or guanidinium cations results, in addition to the expected [Ru(NN)(CN)(4)](2) salts, in the formation of small amounts of salts of the dinuclear species [Ru-2(NN)(2)(CN)(7)](3). These cyanide-bridged anions have arisen from the combination of two monomer units [Ru(NN)(CN)(4)](2) following the loss of one cyanide, presumably as HCN. The crystal structures of [Nd(H2O)(5.5)][Ru-2(bipy)(2)(CN)(7)] center dot 11H(2)O and [Pr(H2O)(6)][Ru-2(phen)(2)(CN)(7)] center dot 9H(2)O show that the cyanoruthenate anions form Ru-CN-Ln bridges to the Ln(III) cations, resulting in infinite coordination polymers consisting of fused Ru(2)Ln(2)(mu-CN)(4) squares and Ru(4)Ln(2)(mu-CN)(6) hexagons, which alternate to form a one-dimensional chain. In [CH6N3](3)[Ru-2(bipy)(2)(CN)(7)] center dot 2H(2)O in contrast the discrete complex anions are involved in an extensive network of hydrogen-bonding involving terminal cyanide ligands, water molecules, and guanidinium cations. In the [Ru-2(NN)(2)(CN)(7)](3) anions themselves the two NN ligands are approximately eclipsed, lying on the same side of the central Ru-CN-Ru axis, such that their peripheries are in close contact. Consequently, when NN = 4,4'-Bu-t(2)-2,2'-bipyridine the steric bulk of the t-butyl groups prevents the formation of the dinuclear anions, and the only product is the simple salt of the monomer, [CH6N3](2)[Ru((t)Bu(2)bipy)(CN)(4)] center dot 2H(2)O. We demonstrated by electrospray mass spectrometry that the dinuclear by-product [Ru-2(phen)(2)(CN)(7)](3) could be formed in significant amounts during the synthesis of monomeric [Ru(phen)(CN)(4)](2) if the reaction time was too long or the medium too acidic. In the solid state the luminescence properties of [Ru-2(bipy)(2)(CN)(7)](3) (as its guanidinium salt) are comparable to those of monomeric [Ru(bipy)(CN)(4)](2), with a (MLCT)-M-3 emission at 581 nm

Isolation and Genetic Characterization of Rift Valley fever virus from Aedes vexans arabiensis, Kingdom of Saudi Arabia

An outbreak of Rift Valley fever in the Kingdom of Saudi Arabia and Yemen in 2000 was the first recognized occurrence of the illness outside of Africa and Madagascar. An assessment of potential mosquito vectors in the region yielded an isolate from Aedes vexans arabiensis, most closely related to strains from Madagascar (1991) and Kenya (1997)

The next detectors for gravitational wave astronomy

This paper focuses on the next detectors for gravitational wave astronomy which will be required after the current ground based detectors have completed their initial observations, and probably achieved the first direct detection of gravitational waves. The next detectors will need to have greater sensitivity, while also enabling the world array of detectors to have improved angular resolution to allow localisation of signal sources. Sect. 1 of this paper begins by reviewing proposals for the next ground based detectors, and presents an analysis of the sensitivity of an 8 km armlength detector, which is proposed as a safe and cost-effective means to attain a 4-fold improvement in sensitivity. The scientific benefits of creating a pair of such detectors in China and Australia is emphasised. Sect. 2 of this paper discusses the high performance suspension systems for test masses that will be an essential component for future detectors, while sect. 3 discusses solutions to the problem of Newtonian noise which arise from fluctuations in gravity gradient forces acting on test masses. Such gravitational perturbations cannot be shielded, and set limits to low frequency sensitivity unless measured and suppressed. Sects. 4 and 5 address critical operational technologies that will be ongoing issues in future detectors. Sect. 4 addresses the design of thermal compensation systems needed in all high optical power interferometers operating at room temperature. Parametric instability control is addressed in sect. 5. Only recently proven to occur in Advanced LIGO, parametric instability phenomenon brings both risks and opportunities for future detectors. The path to future enhancements of detectors will come from quantum measurement technologies. Sect. 6 focuses on the use of optomechanical devices for obtaining enhanced sensitivity, while sect. 7 reviews a range of quantum measurement options

High Log-Scale Expansion of Functional Human Natural Killer Cells from Umbilical Cord Blood CD34-Positive Cells for Adoptive Cancer Immunotherapy

Immunotherapy based on natural killer (NK) cell infusions is a potential adjuvant treatment for many cancers. Such therapeutic application in humans requires large numbers of functional NK cells that have been selected and expanded using clinical grade protocols. We established an extremely efficient cytokine-based culture system for ex vivo expansion of NK cells from hematopoietic stem and progenitor cells from umbilical cord blood (UCB). Systematic refinement of this two-step system using a novel clinical grade medium resulted in a therapeutically applicable cell culture protocol. CD56+CD3− NK cell products could be routinely generated from freshly selected CD34+ UCB cells with a mean expansion of >15,000 fold and a nearly 100% purity. Moreover, our protocol has the capacity to produce more than 3-log NK cell expansion from frozen CD34+ UCB cells. These ex vivo-generated cell products contain NK cell subsets differentially expressing NKG2A and killer immunoglobulin-like receptors. Furthermore, UCB-derived CD56+ NK cells generated by our protocol uniformly express high levels of activating NKG2D and natural cytotoxicity receptors. Functional analysis showed that these ex vivo-generated NK cells efficiently target myeloid leukemia and melanoma tumor cell lines, and mediate cytolysis of primary leukemia cells at low NK-target ratios. Our culture system exemplifies a major breakthrough in producing pure NK cell products from limited numbers of CD34+ cells for cancer immunotherapy

Adhesion Awareness: A National Survey of Surgeons

Contains fulltext : 87943.pdf (publisher's version ) (Closed access)BACKGROUND: Postoperative adhesions are the most frequent complication of abdominal surgery, leading to high morbidity, mortality, and costs. However, the problem seems to be neglected by surgeons for largely unknown reasons. METHODS: A survey assessing knowledge and personal opinion about the extent and impact of adhesions was sent to all Dutch surgeons and surgical trainees. The informed-consent process and application of antiadhesive agents were questioned in addition. RESULTS: The response rate was 34.4%. Two thirds of all respondents (67.7%) agreed that adhesions exert a clinically relevant, negative effect. A negative perception of adhesions correlated with a positive attitude regarding adhesion prevention (rho = 0.182, p < 0.001). However, underestimation of the extent and impact of adhesions resulted in low knowledge scores (mean test score 37.6%). Lower scores correlated with more uncertainty about indications for antiadhesive agents which, in turn, correlated with never having used any of these agents (rho = 0.140, p = 0.002; rho = 0.095, p = 0.035; respectively). Four in 10 respondents (40.9%) indicated that they never inform patients on adhesions and only 9.8% informed patients routinely. A majority of surgeons (55.9%) used antiadhesive agents in the past, but only a minority (13.4%) did in the previous year. Of trainees, 82.1% foresaw an increase in the use of antiadhesive agents compared to 64.5% of surgeons (p < 0.001). CONCLUSIONS: The magnitude of the problem of postoperative adhesions is underestimated and informed consent is provided inadequately by Dutch surgeons. Exerting adhesion prevention is related to the perception of and knowledge about adhesions.1 december 201

The XMM Cluster Survey: testing chameleon gravity using the profiles of clusters

The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak lensing profiles, one can place upper limits on the strength of a fifth force. This technique has been attempted before using a single, nearby cluster (Coma, z = 0.02). Here we apply the technique to the stacked profiles of 58 clusters at higher redshifts (0.1 < z < 1.2), including 12 new to the literature, using X-ray data from the XMM Cluster Survey and weak lensing data from the Canada-France-Hawaii-Telescope Lensing Survey. Using a multiparameter Markov chain Monte Carlo analysis, we constrain the two chameleon gravity parameters (beta and phi∞). Our fits are consistent with general relativity, not requiring a fifth force. In the special case of f(R) gravity (where beta = &surd;{1/6}), we set an upper limit on the background field amplitude today of |fR0| < 6 × 10-5 (95 per cent CL). This is one of the strongest constraints to date on |fR0| on cosmological scales. We hope to improve this constraint in future by extending the study to hundreds of clusters using data from the Dark Energy Survey