bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eulerian and Lagrangian aspects of surface waves
Authors: Longuet-Higgins M. S. 
Published: April 2006

Surface waves can be recorded in two kinds of ways, either with a fixed (Eulerian) probe or with a free-floating (Lagrangian) buoy. In steep waves, the differences between corresponding properties can be very marked.By a simple physical model and by accurate calculation it is shown that the Lagrangian wave period may differ from the Eulerian wave period by as much as 38 %. The Lagrangian mean level is also higher than the Eulerian mean, leading to possible discrepancies in remote sensing of the ocean from satellites.Surface accelerations are of interest in relation to the incidence of breaking waves, and for interactions between short (gravity or capillary) waves and longer gravity waves. Eulerian accelerations tend to be very non-sinusoidal, with large downwards peaks, sometimes exceeding -gin magnitude, near to sharp wave crests. Lagrangian accelerations are much smoother; for uniform gravity waves they lie between −0.388gand +0.315g. These values are verified by laboratory experiments. In wind-generated waves the limits are probably wider.In progressive gravity waves in deep water the horizontal accelerations generally exceed the vertical accelerations. In steep waves, the subsurface accelerations can slightly exceed those at the free surface.A novel application is made to the rolling motion of ships. In very steep, irrotational waves it is shown theoretically that the flow near the wave crest can lead to the rotation of the hull through angles up to 120° by a single wave, even if the wave is not breaking. This is confirmed by simple experiments. The efficiency of the keel appears to promote capsizing.
The stability of inviscid flows over passive compliant walls
Authors: Yeo K. S. , Dowling A. P. 
Published: April 2006

The linear temporal stability of incompressible semi-bounded inviscid parallel flows over passive compliant walls is studied. It is shown that some of the well-known classical results for inviscid parallel flows with rigid boundaries can, in fact, be extended in modified form to passive compliant walls. These include a result of Rayleigh (1880) which shows that the real part of the phase velocity of a non-neutral disturbance must lie within the range of the velocity distribution; the semi-circle theorem of Howard (1961) and a result of Høiland (1953) which places a bound on the temporal amplification rates of unstable disturbances. The bounds on the phase velocity and the temporal amplification rates of unstable two-dimensional disturbances provide useful guides for numerical studies.The results are valid for a large class of passive compliant walls. This generality is achieved through a variational-Lagrangian formulation of the essential dynamics of wall motion. A general treatment of the marginal stability of thin shear flows over general passive compliant walls is given. It represents a generalization of the analysis given by Benjamin (1963) for membrane and plate surfaces. Sufficient conditions for the stability of thin shear flows over passive compliant walls are deduced. The applications of the stability criteria to simple cases of compliant wall are described to illustrate the use and the effectiveness of these criteria.
A boundary-element analysis of flagellar propulsion
Authors: Phan-Thien N. , Tran-Cong T. , Ramia M. 
Published: April 2006

The swimming of a flagellar micro-organism by the propagation of helical waves along its flagellum is analysed by a boundary-element method. The method is not restricted to any particular geometry of the organism nor does it assume a specific wave motion for the flagellum. However, only results for an organism with a spherical or ellipsoidal cell body and a helically beating flagellum are presented here.With regard to the flagellum, it is concluded that the optimum helical wave (amplitude α and wavenumber k) has αk ≈ 1 (pitch angle of 45°) and that for the optimum flagellar length L/A = 10 (L being the flagellar length, A being the radius of the assumed spherical cell body) the optimum number of wavelengths Nλ is about 1.5. Furthermore there appears to be no optimal value for the flagellar radius a, with the thinner flagella being favoured. These conclusions show excellent quantitative agreement with those of slender-body theory.For the case of an ellipsoidal cell body, the optimum aspect ratios B/A and C/A of the ellipsoid are about 0.7 and 0.3 respectively; A, B and C are the principal radii of the ellipsoid. These and all of the above conclusions show good qualitative agreement with experimental observations of efficiently swimming micro-organisms.
Jeffery-Hamel boundary-layer flows over curved beds
Authors: Eagles P. M. 
Published: April 2006

We find certain exact solutions of Jeffery-Hamel type for the boundary-layer equations for film flow over certain beds. If β is the angle of the bed with the horizontal and S is the arclength these beds have equation sin β = (const.)S−3, and allow a description of flows on concave and convex beds. The velocity profiles are markedly different from the semi-Poiseuille flow on a plane bed.We also find a class of beds in which the Jeffery-Hamel flows appear as a first approximation throughout the flow field, which is infinite in streamwise extent. Since the parameter γ specifying the Jeffery-Hamel flow varies in the streamwise direction this allows a description of flows over curved beds which are slowly varying, as described in the theory, in such a way that the local approximation is that Jeffery-Hamel flow with the local value of γ. This allows the description of flows with separation and reattachment of the main stream in some cases.
Studying turbulence using direct numerical simulation: 1987 Center for Turbulence Research NASA Ames/Stanford Summer Programme
Authors: Hunt J. C. R. 
Published: April 2006

This paper is an account of a summer programme for the study of the ideas and models of turbulent flows, using the results of direct numerical stimulations of the Navier-Stokes equations. These results had been obtained on the computers and stored as accessible databases at the Center for Turbulence Research (CTR) of NASA Ames Research Center and Stanford University. At this first summer programme, some 32 visiting researchers joined those at the CTR to test hypotheses and models in five aspects of turbulence research: turbulence decomposition, bifurcation and chaos; two-point closure (or k-space) modelling; structure of turbulent boundary layers; Reynolds-stress modelling; scalar transport and reacting flows.A number of new results emerged including: computation of space and space-time correlations in isotropic turbulence can be related to each other and modelled in terms of the advection of small scales by large-scale motion; the wall layer in turbulent boundary layers is dominated by shear layers which protrude into the outer layers, and have long lifetimes; some aspects of the ejection mechanism for these layers can be described in terms of the two-dimensional finite-amplitude Navier-Stokes solutions; a self-similar form of the two-point, cross-correlation data of the turbulence in boundary layers (when normalized by the r.m.s. value at the furthest point from the wall) shows how both the blocking of eddies by the wall and straining by the mean shear control the lengthscales; the intercomponent transfer (pressure-strain) is highly localized in space, usually in regions of concentrated vorticity; conditioned pressure gradients are linear in the conditioning of velocity and independent of vorticity in homogeneous shear flow; some features of coherent structures in the boundary layer are similar to experimental measurements of structures in mixing-layers, jets and wakes.The availability of comprehensive velocity and pressure data certainly helps the investigation of concepts and models. But a striking feature of the summer programme was the diversity of interpretation of the same computed velocity fields. There are few signs of any convergence in turbulence research! But with new computational facilities the divergent approaches can at least be related to each other.
Determination of the biliary excretion of piperacillin in humans using a novel method
Authors: Ghibellini Giulia , Vasist Lakshmi S. , Hill Terence E. , Heizer William D. , Kowalsky Richard J. , Brouwer Kim L. R. 
Published: April 2006

AimTo evaluate the applicability of a novel method to determine the biliary excretion of piperacillin.MethodsHealthy volunteers were administered piperacillin i.v. Duodenal aspirates were collected via a custom‐made oroenteric catheter; blood and urine also were collected. Gallbladder ejection fraction (EF) was determined by gamma scintigraphy and pharmacokinetic parameters were calculated using noncompartmental analysis.ResultsThe fraction of the piperacillin dose excreted unchanged into bile was 1.1 ± 0.3% (biliary clearance corrected for EF was 0.032 ± 0.008 ml min−1 kg−1).ConclusionsThis methodology can be used to determine reliably the biliary clearance of drugs that are excreted only marginally into bile. Normalization of biliary clearance for EF significantly reduces intersubject variability of this parameter.
Legislation restricting paracetamol sales and patterns of self‐harm and death from paracetamol‐containing preparations in Scotland
Authors: Bateman D. N. , Gorman D. R. , Bain M. , Inglis J. H. C. , House F. R. , Murphy D. 
Published: April 2006

AimsTo describe how changes in legislation to restrict paracetamol sales have affected overdose discharges and death associated with the drug in Scotland.MethodsA descriptive analysis of routine death and hospital discharge data for the entire Scottish population between 1995 and 2004. Patients in Scotland participated who were discharged from hospital with a diagnosis of poisoning; deaths in Scotland from diagnosis of poisoning 1995–2003 were also analysed. Outcome measures were changes in mortality and overdose due to poisoning involving paracetamol. A comparison was made of in‐hospital and out‐of‐hospital mortality in fatalities involving paracetamol.ResultsThe majority of paracetamol‐associated deaths were due to co‐proxamol. Deaths associated with paracetamol alone or with ethanol occurred principally in hospital and were a minority of deaths overall. The proportion of in‐hospital deaths attributed to paracetamol increased (post/pre ratio 1.347; 95% confidence interval 1.076, 1.639;P = 0.013). Overall numbers of cases discharged with poisoning fell. The proportion of these involving paracetamol in any form increased significantly in all groups except young men aged 10 to <20 years.ConclusionsLegislation has not reduced mortality or proportional use of paracetamol in overdose, both of which appear to have increased in Scotland since pack‐size limitations. Other approaches are necessary to reduce the death rate from overdoses involving paracetamol.
Novel mutations in the calcium‐sensing receptor gene associated with biochemical and functional differences in familial hypocalciuric hypercalcaemia
Authors: Ward Bryan K. , Magno Aaron L. , Blitvich Bradley J. , Rea Alexander J. , Stuckey Bronwyn G. A. , Walsh John P. , Ratajczak Thomas 
Published: April 2006

SummaryObjective  Heterozygous inactivating mutations of the calcium‐sensing receptor (CaR) gene cause familial hypocalciuric hypercalcaemia (FHH), a generally benign disorder characterized by mild to moderate PTH‐dependent hypercalcaemia. We aimed to identify the causative CaR mutations in three families with FHH and examine the correlation between type of mutation and biochemical and/or functional phenotypes.Patients, design and measurements  The CaR gene from FHH family members was assessed for mutations by direct DNA sequencing and mutations were confirmed by restriction enzyme analysis. Functional studies on two missense mutations were conducted by introducing them by site‐directed mutagenesis into the CaR cloned into a mammalian expression vector, and assessing calcium responsiveness using an inositol phosphate (IP) assay in HEK293 cells. Biochemical data from patients heterozygous for each type of mutant were correlated with functionality.Results  Two novel nonsense mutations (R25stop and K323stop) and one novel missense mutation (G778D) were identified. The G778D mutant receptor and another mutation identified in an earlier study (L174R) demonstrated a complete lack of Ca2+ responsiveness using the IP assay. When cotransfected with wild‐type receptor, the mutant receptors demonstrated a dominant‐negative effect on wild‐type receptor response, with L174R having a more pronounced effect than G778D. Significantly more severe hypercalcaemia and a trend towards higher PTH levels were observed in patients heterozygous for CaR mutants with a stronger dominant‐negative effect.Conclusions  Naturally occurring CaR mutations with differences in dominant‐negative effect on wild‐type receptor demonstrate differences in biochemical severity in FHH.
Higher daytime leaf temperatures contribute to lower freeze tolerance under elevated CO2
Authors: LOVEYS BETH R. , EGERTON JOHN J. G. , BALL MARILYN C. 
Published: April 2006

ABSTRACTElevated atmospheric CO2 adversely affects freezing tolerance in many evergreens, but the underlying mechanism(s) have been elusive. We compared effects of elevated CO2 with those of daytime warming on acclimation of snow gum (Eucalyptus pauciflora) to freezing temperatures under field conditions. Reduction in stomatal conductance gc under elevated CO2 was shown to cause leaf temperature to increase by up to 3 °C. In this study, this increase in leaf temperature was simulated under ambient CO2 conditions by using a free air temperature increase (FATI) system to warm snow gum leaves during daytime, thereby increasing the diurnal range in temperature without affecting temperature minima. Acclimation to freezing temperatures was assessed using measures of electrolyte leakage and photosynthetic efficiency of leaf discs exposed to different nadir temperatures. Here, we show that both elevated CO2 and daytime warming delayed acclimation to freezing temperatures for 2–3 weeks after which time freeze tolerance of the treated plants in both the FATI and open top chamber (OTC) experiments did not differ from control plants. Our results support the hypothesis that delayed development of freezing tolerance under elevated CO2 is because of higher daytime leaf temperatures under elevated CO2. Thus, potential gains in productivity in response to increasing atmospheric CO2 and prolonging the growing season may be reduced by an increase in freezing stress in frost‐prone areas.
Can fast‐growing plantation trees escape biochemical down‐regulation of photosynthesis when grown throughout their complete production cycle in the open air under elevated carbon dioxide?
Authors: DAVEY P. A. , OLCER H. , ZAKHLENIUK O. , BERNACCHI C. J. , CALFAPIETRA C. , LONG S. P. , RAINES C. A. 
Published: April 2006

ABSTRACTPoplar trees sustain close to the predicted increase in leaf photosynthesis when grown under long‐term elevated CO2 concentration ([CO2]). To investigate the mechanisms underlying this response, carbohydrate accumulation and protein expression were determined over four seasons of growth. No increase in the levels of soluble carbohydrates was observed in the young expanding or mature sun leaves of the three poplar genotypes during this period. However, substantial increases in starch levels were observed in the mature leaves of all three poplar genotypes grown in elevated [CO2]. Despite the very high starch levels, no changes in the expression of photosynthetic Calvin cycle proteins, or in the starch biosynthetic enzyme ADP‐glucose pyrophosphorylase (AGPase), were observed. This suggested that no long‐term photosynthetic acclimation to CO2 occurred in these plants. Our data indicate that poplar trees are able to ‘escape’ from long‐term, acclimatory down‐regulation of photosynthesis through a high capacity for starch synthesis and carbon export. These findings show that these poplar genotypes are well suited to the elevated [CO2] conditions forecast for the middle of this century and may be particularly suited for planting for the long‐term carbon sequestration into wood.
Prohibitin is involved in mitochondrial biogenesis in plants
Authors: Ahn Chang Sook , Lee Jeong Hee , Reum Hwang A , Kim Woo Taek , Pai Hyun‐Sook 
Published: April 2006

SummaryProhibitin, which consists of two subunits PHB1 and PHB2, plays a role in cell‐cycle progression, senescence, apoptosis, and maintenance of mitochondrial function in mammals and yeast. In this study, we examined the role of prohibitins in plants by using virus‐induced gene silencing (VIGS) of two prohibitin subunit genes of Nicotiana benthamiana, designated NbPHB1 and NbPHB2. NbPHB1 and NbPHB2 were targeted to the mitochondria, and their gene expression was suppressed during senescence. VIGS of NbPHB2 caused severe growth inhibition, leaf yellowing and symptoms of cell death, whereas VIGS of NbPHB1 resulted in a milder phenotype. At the cellular level, depletion of these subunits affected mitochondria by severely reducing their number and/or mass, and by causing morphological and physiological abnormalities. Suppression of prohibitin function resulted in a 10‐ to 20‐fold higher production of reactive oxygen species and induced premature leaf senescence. Finally, disruption of prohibitin function rendered the plants more susceptible to various oxidative stress‐inducing reagents, including H2O2, paraquat, antimycin A and salicylic acid. These results suggest that prohibitins play a crucial role in mitochondrial biogenesis and protection against stress and senescence in plant cells.
Comparison of the efficacy of rabeprazole 10 mg and omeprazole 20 mg for the healing rapidity of peptic ulcer diseases
Authors: Ji Sangwon , Kim Hyun Soo , Kim Jae Woo , Jee Myeong Kwan , Park Kwang Wha , Uh Young , Lee Dong Ki , Song Jae Suk , Baik Soon Koo , Kwon Sang Ok 
Published: April 2006

AbstractAim: Rabeprazole has been known to inhibit H+/K+‐ATPase more rapidly than omeprazole, the prototype proton pump inhibitor (PPI). The aim of this study was to demonstrate equivalence between low‐dose rabeprazole 10 mg and omeprazole 20 mg for the healing rapidity of active peptic ulcer and for improvement of symptoms. Also, the effect of CYP2C19 genotypes on ulcer healing rapidity was investigated.Methods: A total of 112 patients with active peptic ulcer were randomized to receive either rabeprazole 10 mg q.d. or omeprazole 20 mg q.d. for 6 weeks. The remaining ratios (%) and complete healing of the ulcer were determined by endoscopy at 1 week and 6 weeks of treatment. The severity of ulcer pain was also investigated during treatment. CYP2C19 genotype was determined by the polymerase chain reaction‐restriction fragment length polymorphism (PCR‐RFLP) method.Results: The remaining ratio of peptic ulcers after 1 week and the complete healing rate after 6 weeks in the rabeprazoleversusomeprazole group were 45.5%versus50.3% (P = 0.475) and 80.6%versus87.0% (P = 0.423), respectively. CYP2C19 genotypes had no effect on the remaining ratio of peptic ulcers after 1 week and the healing rate of peptic ulcers after 6 weeks in both groups. The proportions of patients with symptom improvement or resolution were comparable between the two groups.Conclusion: Low‐dose rabeprazole 10 mg has a similar efficacy for the healing rapidity of active peptic ulcer disease and symptom improvement compared with standard‐dose omeprazole 20 mg.
Zinc L‐carnosine protects against mucosal injury in portal hypertensive gastropathy through induction of heat shock protein 72
Authors: Mikami Ken‐Ichiro , Otaka Michiro , Watanabe Daisuke , Goto Takashi , Endoh Ayako , Miura Kouichi , Ohshima Shigetoshi , Yoneyama Kazuo , Sato Michiko , Shibuya Tomomi , Segawa Daisuke , Kataoka Ei , Yoshino Ryutaro , Takeuchi Satoko , Sato Wataru , Odashima Masaru , Watanabe Sumio 
Published: April 2006

AbstractBackground and Aims:  Increased susceptibility to gastric mucosal injury is observed in portal hypertensive gastropathy (PHG). In this study, the effects of zinc L‐carnosine, an anti‐ulcer drug, were evaluated on expression of heat shock protein (hsp) 72 and cytoprotection in gastric mucosa in a rat model of PHG.Methods:  Portal hypertensive gastropathy with liver cirrhosis was induced by bile duct ligation for 4 weeks in male Sprague–Dawley rats. Expression of gastric mucosal hsp72 was evaluated by Western blotting at 6 h after intragastric administration of L‐carnosine, zinc sulfate, or zinc L‐carnosine. Blood was also collected for determination of serum zinc level. Mucosal protective abilities against hydrochloric acid (HCl) (0.6N) followed by pretreatment with L‐carnosine, zinc sulfate or zinc L‐carnosine were also studied.Results:  L‐carnosine, zinc sulfate, and zinc L‐carnosine induced hsp72 in gastric mucosa of rats with bile duct ligation. Zinc sulfate and zinc L‐carnosine suppressed HCl‐induced mucosal injury. However, L‐carnosine could not suppress HCl‐induced mucosal injury. Serum zinc levels were significantly elevated after zinc L‐carnosine administration. Furthermore, pretreatment with zinc L‐carnosine (30–300 mg/kg) increased the expression of hsp72 in gastric mucosa and prevented HCl‐induced mucosal injury in rats with bile duct ligation in a dose‐dependent manner.Conclusions:  Zinc derivatives, especially zinc L‐carnosine, protected portal hypertensive gastric mucosa with increased hsp72 expression in cirrhotic rats. It is postulated that zinc L‐carnosine may be beneficial to the mucosal protection in PHG as a ‘chaperon inducer’.