bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positive super-solutions to semi-linear second-order non-divergence type elliptic equations in exterior domains
Authors: Kondratiev Vladimir , Liskevich Vitali , Sobol Zeev 
Published: October 2008

We study the problem of the existence and non-existence of positive super-solutions to a semi-linear second-order non-divergence type elliptic equation

∑

i
,
j
=
1

N

a

i
j

(
x
)

∂
2

u

∂

x
i

∂

x
j

+

u
p

=
0

\sum _{i,j=1}^N a_{ij}(x)\frac {\partial ^2 u}{\partial x_i \partial x_j}+u^p=0

,

−
∞
>
p
>
∞

-\infty >p>\infty

, with measurable coefficients in exterior domains of

R

N

\mathbb {R}^N

. We prove that in a “generic” situation there is one critical value of

p
p

that separates the existence region from non-existence. We reveal the quantity responsible for the qualitative picture and for the numerical value of the critical exponent which becomes available under a mild stabilization condition at infinity.
Contribution of monoaminergic modulation to the analgesic effect of tramadol
Authors: DESMEULES J. A. , PIGUET V. , COLLART L. , DAYER P. 
Published: October 2008

1 In humans, the central analgesic effect of tramadol 100 mg orally is only partially reversed by the opioid antagonist naloxone (0.8 mg intravenously). As suggested byin vitroand animal data tramadol analgesia may thus result from an action on opioid as well as monoaminergic pathways. We therefore investigated the effect of α2‐adrenoceptor antagonism with yohimbine on tramadol analgesia.2 Healthy volunteers (n = 10) received tramadol (100 mg orally), followed (+3 h) by yohimbine (0.1 mg kg‐1intravenously), and yohimbine + naloxone (0.8 mg intravenously) and their respective placebo according to a randomized, double‐blind crossover, placebo (P) controlled design. Analgesia was assessed over 8 h by subjective pain threshold (pain intensity numerical scale–PINS) and objective pain threshold (RIII nociceptive reflex–RIII) monitoring.3 Tramadol induced a significant increase in both pain thresholds. Peak analgesic effect was observed at 3.7 h (RIII+ 39.6±3.9% and PINS 50.1±s.e.mean 5%) and the analgesia lasted about 6 h.4 Yohimbine significantly reversed the analgesic effects of tramadol for 2.8 h with a maximum decrease of 97±4% (RIII) and 67±12% (PINS), whereas the addition of naloxone abolished tramadol effects throughout the study period with a decrease of 90±6% (RIII) and 79±9% (PINS), P<0.05).5 Yohimbine alone did not significantly reduce pain thresholds.6 α2‐Adrenoceptor antagonism reverses tramadol effects, thus pointing to the significant role of monoaminergic modulation and the synergy with opioid agonism in tramadol antinociception after a single oral dose.
Cyclophosphamide pharmacokinetics in children
Authors: YULE S. M. , BODDY A. V. , COLE M. , PRICE L. , WYLLIE R. , TASSO M. J. , PEARSON A. D. J. , IDLE J. R. 
Published: October 2008

1 Cyclophosphamide pharmacokinetics were measured in 38 children with cancer.2 A high degree of inter‐patient variation was seen in all pharmacokinetic parameters. Cyclophosphamide half‐life varied between 1.1 and 16.8 h, clearance varied between 1.2 and 10.61 h‐1m‐2and volume of distribution varied between 0.26 and 1.48 1kg‐1.3 The half–life of cyclophosphamide was prolonged at high dose levels (P = 0.008).4 Children who had received prior treatment with dexamethasone showed a mean increase in clearance of 2.5 1 h‐1m‐2(P= 0.001) presumably as a result of CYP450 enzyme induction.5 Treatment with allopurinol or chlorpromazine was associated with a significant increase in cyclophosphamide half‐life (P< 0.001 in both cases).6 Dose and concurrent treatment may influence cyclophosphamide metabolismin vivoand thus potentially alter the drugs therapeutic effect.
Comparison of the steady‐state pharmacokinetics of nefazodone after administration of 200 mg twice daily or 400 mg once daily in the morning or evening
Authors: MARATHE PUNIT H. , LEE JAMES S. , GREENE DOUGLAS S. , BARBHAIYA RASHMI H. 
Published: October 2008

The steady‐state pharmacokinetics of nefazodone, an antidepressant drug with non‐linear pharmacokinetics, were determined in a multiple‐dose, three‐period crossover study in 24 male volunteers to evaluate whether administration of the same total daily dose of nefazodone by different dosing schedules has an effect on systemic exposure to the drug and its metabolites.Three treatments administered were: a 400 mg dose once daily in the a.m. (treatment 1) or in the p.m. (treatment 2) for 5 days or a 200 mg twice daily (every 12 h, a.m. and p.m.) dose daily for 7 days (treatment 3). Prior to the administration of the 400 mg once daily dose, the subjects were administered 200 mg nefazodone once daily (a.m. or p.m.) for 2 days. There was a 7 day washout between treatments.Serial blood samples were collected up to 72 h post dose for treatment 1 and treatment 2 and up to 84 h post a.m. dose for treatment 3 on day 7 for determination of pharmacokinetic parameters. Blood samples for trough (Cmin) plasma concentrations were also obtained on days 5, 6 and 7 of each treatment to assess attainment of steady state. Plasma samples were assayed for nefazodone and its metabolites, hydroxynefazodone,m‐chlorophenylpiperazine and triazoledione by a validated h.p.l.c./u.v. assay.The Cmindata indicated that nefazodone and its metabolites reached steady state by study day 5 of each treatment period.Mean steady‐state pharmacokinetic parameter values were similar among treatments. Statistical analyses indicated that, as reflected by AUC(0,24 h) and the ratios of individual nefazodone metabolite AUCs to nefazodone AUC over a dosing interval, there were no differences in steady‐state exposure to nefazodone and its metabolites among treatments. For NEF, AUC(0,24 h) (point estimate and 90% CI) values were 102% (86%,119%) for 400 mg a.m. and 91% (76%.105%) for 400 mg p.m. when compared with the 200 mg twice daily.Although there were some small differences in mean pharmacokinetic parameter values after a.m. and p.m. administration, no consistent diurnal variation was observed in the pharmacokinetics of nefazodone or its metabolites.There were no serious or unexpected adverse events noted in the study.It is concluded that despite the nonlinearity in the pharmacokinetics of nefazodone, the exposure to nefazodone and its metabolites is comparable for the once daily (400 mg) and twice daily (200 mg) treatments.
Paracetamol and its metabolites in saliva and plasma in chronic dialysis patients
Authors: LEE H. S. , TI T. Y. , LYE W. C. , KHOO Y. M. , TAN C. C. 
Published: October 2008

1 Many pharmacokinetic studies on paracetamol are based on saliva paracetamol concentrations. The utility of saliva in patients with chronic renal failure is unclear. In this study, concentrations of saliva and plasma paracetamol and its major metabolites, sulphate and glucuronide conjugates were determined at 0.5, 1, 2 and 3 h after the ingestion of 1 g paracetamol in 20 patients with end‐stage renal failure. Ten haemodialysis patients were studied on a non‐haemodialysis day and during a haemodialysis session. The other 10 patients were on chronic ambulatory peritoneal dialysis.2 The plasma paracetamol concentrations attained in all groups were not different from those reported previously in healthy subjects. Mean±s.d. plasma paracetamol concentrations at 0.5 h in haemodialysis patients on a non‐haemodialysis day, during haemodialysis and in those on chronic ambulatory peritoneal dialysis were 15.3±8.2, 21.5±10.9 and 18.2±12.3 μg ml‐1respectively.3 The saliva paracetamol concentrations were highly variable and unpredictable. Saliva paracetamol concentrations at 1, 2 and 3 h after ingestion in the haemodialysis group during haemodialysis were 31.5±20.1, 14.1±10.4 and 7.3±3.8 μg ml‐1respectively, significantly (P <0.05; paired t‐test) higher than the corresponding plasma paracetamol concentrations which were 11.0±2.8, 6.5±2.8 and 3.2±0.9 μg ml‐1respectively.4 Correlation coefficients between saliva and plasma paracetamol concentrations in haemodialysis patients on a non‐haemodialysis day and during haemodialysis and in chronic ambulatory peritoneal dialysis patients were poor;r= 0.58 (P< 0.0002);r= 0.40 (P<0.02); andr= 0.13 (P= 0.49) respectively.5 Three hours after paracetamol ingestion, plasma paracetamol, sulphate and glucuronide concentrations were significantly (P<0.05) reduced in haemodialysis patients during haemodialysis when compared with the same patients on a non–haemodialysis day (paired t‐test) and to the chronic ambulatory peritoneal dialysis group (Kruskal‐Wallis ANOVA) except for plasma glucuronide. This indicates the effective removal of paracetamol and metabolites by haemodialysis. In contrast, chronic ambulatory peritoneal dialysis seemed to remove glucuronide only.6 In the light of the poor correlation between saliva and plasma paracetamol in dialysis patients in this study, we would like to caution against using saliva paracetamol concentrations for pharmacokinetic studies in this group of patients.
The tolerability and pharmacokinetics of the novel antimigraine compound 311C90 in healthy male volunteers
Authors: SEABER E. , ON N. , PHILLIPS S. , CHURCHUS R. , POSNER J. , ROLAN P. 
Published: October 2008

1 311C90 is a novel and selective agonist at 5‐HT1D receptors, with central and peripheral actions, currently in development for the acute oral treatment of migraine.2 The pharmacokinetic and tolerability profiles of single oral doses from 1–50 mg 311C90 were investigated in 12 healthy male volunteers in a double‐blind, placebo‐controlled, dose‐escalating study.3 311C90 was well tolerated with most adverse experiences of mild and transient nature.4 Absorption was rapid with dose‐independent kinetics. Median tmax was 2–4 h although 50–85% of eventual Cmax was attained within 1 h. The t1/2 was 2.5‐3 h with a high apparent plasma clearance (CL/F > 2000 ml min‐1) and apparent volume of distribution (VZ/F) of 400–5001.5 Three metabolites were detected in plasma and urine, one of which, the N‐desmethyl metabolite, has 5‐HT1D agonist activity.6 311C90 showed no clinically significant effects on blood pressure, heart rate, ECG or laboratory variables at any dose and demonstrated a tolerability and pharmacokinetic profile compatible with an acute oral migraine treatment.
Theophylline population pharmacokinetics from routine monitoring data in very premature infants with apnoea
Authors: LEE T. C. , CHARLES B. G. , STEER P. A. , FLENADY V. J. , GRANT T. C. 
Published: October 2008

1 Theophylline is commonly used in neonatology for the treatment and prophylaxis of apnoea of prematurity, and during ventilator weaning.2 NONMEM was used to study the population pharmacokinetics of intravenous and oral theophylline from retrospective drug monitoring data in 82 premature neonates, weighing < 1500g at birth, and < 32 weeks gestational age.3 Clearance (CL), volume of distribution (V) and oral bioavailability (F1) from liquid preparations were modelled alone, and under the influence of demographic and clinical covariates, assuming a 1‐compartment model with first‐order elimination.4 The final population models with influential co‐variates were as follows: CL (1h‐1) = 0.0000123 *body weight (g) + 0.000377 *postnatal age (days);V(1) = 0.000937 *body weight (g);F= 0.918.5 The CL was lower andVwas higher than previously reported for less premature neonates, term babies, and older children.6 Predictive performance of the population models was evaluated by Bayesian forecasting in a similar, but independent cohort of 30 infants. There was statistically insignificant bias and imprecision between measured and predicted serum theophylline concentrations.7 Based on the validated population models, recommended maintenance theophylline dosages are provided for infants aged between 2 and 50 days, and weighing 700 to 2000 g.
Stereoselective sulphate conjugation of salbutamol by human lung and bronchial epithelial cells
Authors: EATON E. ALISON , WALLE U. KRISTINA , WILSON HUGH M. , ABERG GUNNAR , WALLE THOMAS 
Published: October 2008

1 The metabolism of (+)‐, (‐)‐ and (±)‐salbutamol by sulphoconjugation was determinedin vitrousing human lung cytosol and bronchial epithelial BEAS‐2B cell homogenate.2 For the lungs the intrinsic clearance (Vmax/Km) value for the pharmacologically active (‐)‐salbutamol (0.49 ± 0.32 ml min‐‐1g‐1protein) exceeded that of (+)‐salbutamol (0.046 ± 0.028 ml min‐1g‐1protein) by 11‐fold. This was mainly due to a difference inKmvalue, which was 16 times higher for (+)‐salbutamol (1300 ± 170 μM) than for (‐)‐salbutamol (83 ± 12 μM).3 The stereoselectivity of sulphoconjugation of salbutamol was very similar in the BEAS‐2B cells, although the absolute activity was considerably lower.4 The enzyme catalyzing this reaction both in the lungs and in the BEAS‐2B cells was the monoamine (M) form phenolsulphotransferase.5 These observations emphasize that the smooth muscle of the bronchi most likely are exposed to considerably higher concentrations of the potentially toxic (+)‐enantiomer than of the bronchodilating (‐)‐enantiomer during therapy with (±)‐salbutamol.
Distribution and excretion of sumatriptan in human milk
Authors: WOJNAR‐HORTON R. E. , HACKETT L. P. , YAPP P. , DUSCI L. J. , PAECH M. , ILETT K. F. 
Published: October 2008

1 The excretion of a 6 mg subcutaneous dose of sumatriptan in breast milk was studied in five lactating volunteer subjects with a mean age of 27.6 years and a mean body weight of 75 kg. Drug concentrations in milk and plasma over the ensuing 8 h were measured by high‐performance liquid chromatography.2 The mean milk:plasma ratio estimated from the areas under the milk and plasma concentration‐time curves (AUC) was 4.9 (95% CI 4.1–5.7), indicating a significant transfer of sumatriptan into the milk compartment.3 The mean total recovery of drug in milk was estimated to be only 14.4 μg (95% CI 6.1–22.7 μg), or 0.24% of the 6 mg administered dose. On a weight‐adjusted basis this corresponded to a mean infant exposure of 3.5% of the maternal dose (95% CI 0.3–6.7%).4 If oral bioavailability in the infant is similar to that in adults (14%), the weight‐adjusted infant dose is reduced to 0.49%. Furthermore, allowance for reduced clearance in the infant predicts an infant exposure varying from 4.9% in a very premature neonate to 0.7% in a 30 week old infant.5 Since sumatriptan is usually administered as a single dose at infrequent intervals, the low level of excretion in breast milk suggests that continued breast feeding following its use will not pose a significant risk to the suckling infant. Even this minor exposure could be largely avoided by expressing and discarding all milk for 8 h after the dose.
PHOLOELASTIC INSTRUMENTATION IN CIVIL ENGINEERING STRUCTURES
Authors: HAWKES I. , HOOPER J. A. , ROSE H. 
Published: October 2008

This paper deals with the measurement of stress or load in three structures using photoelastic gauges. Principals of photoelastic gauging are described with reference to the design and installation of a photoelastic stressmeter and gauges to measure earth pressure and steel cable tensions.Applications are described as follows:

The measurement of load distribution between a concrete raft and piles using photoelastic stressmeters and photoelastic earth pressure gauges.
The measurement of stresses in a prestressed box cantilever bridge using photoelastic stressmeters.
The control of tension in the main supporting cables of a large suspension bridge using photoelastic load gauges.
ON A GENERAL METHOD OF COMPENSATION IN STRAIN GAUGE WORK
Authors: MEYER M.L. 
Published: October 2008

If gauges or rosettes identical with those used in testing are affixed to a compensating bar under known stresses and of the same material as the test piece, the required stresses are obtained directly in terms of the known compensating stress and of the measured resistance changes. Cross‐sensitivity, gauge factor and constants of elasticity of the test piece cancel out and errors due to inaccurate assumptions for their values are avoided. If the test strains, elastic or non‐elastic, are required and the elastic compensating strain is known, Poisson's ratio of the compensator enters into the evaluation. A region of the test piece where stresses or strains are known may serve as a compensator.One compensating rosette or two single compensating gauges suffice for any number of identical testing gauges. Initial zero balance may not always be needed and special circuits facilitate evaluation, which lends itself to simple self‐contained automation. An analogue unit suggested for incorporation in a strain meter allows direct display of principal stresses and directions from rosette measurements.
On the application of complex potentials and photoelastic data to the solution of plane problems
Authors: THOMPSON J. C. , ABOU–EL–ATTA H. 
Published: October 2008

This article demonstrates the accuracy and convenience of a recently developed analytical technique for determining the stress and displacement fields for plane problems from point‐wise photoelastic data and finite order, polynomial approximations of complex potentials of the Kolosoff type. The order of the approximations is consistent with the assumption of a stress field which varies essentially in a quadratic manner within each region or subregion in which the approximations are fitted to the photoelastic data.The theoretical basis of the technique is reviewed briefly and the method is then applied to the problems of an end‐loaded cantilever, a ring and a disc under diametral compression, and a vertical point load on a half‐space. Uncertainties associated with inevitable errors in experimental data are avoided by generating isoclinic and isochromatic data from the theoretical solutions of the four problems, these ‘photoelastic results’ then forming the basic initial data upon which the technique operates.Computations of the stresses, rotations and displacements indicate that the complex potentials method is equally applicable along lines of symmetry, on contours around point loads, in regions where the stress is predominantly uniaxial in character, and also where the stress field is completely two‐dimensional. The computed and theoretical values are virtually in exact agreement whenever the density of the randomly distributed data points is such that the stress field is accurately approximated by a quadratic function within the region spanned by the data points. The local approximations of the potentials are fitted to the experimental results at these data points.
The application of optical fibres as witness devices for the detection of plastic strain and cracking
Authors: HALE K. F. , HOCKENHULL B. S. , CHRISTODOULOU G. 
Published: October 2008

Low cost optical fibres have recently become readily available for telecommunications purposes. Silica fibres are characterised by high elastic strains to failure. The feasibility of using these fibres for structural integrity monitoring particularly for offshore structures is investigated. The basis of the technique is that a fibre may be bonded to a critical part of a structure and provides an optical path which will be broken if the fibre fails due to plastic strain or crack opening in the critical area.Groups of fibres which have been given predetermined fracture strains by surface etching were encapsulated in special packs. These packs were bonded to steel and concrete tensile specimens. Strain transfer occurred successfully between the specimens and individual fibres. The distribution of strain to fibre fracture appeared to be uniform along the fibre. The use of several fibres with a range of fracture strains caused fibres to break progressively with increasing strain. For applications to offshore structures it has been found possible to use water‐repellent adhesives which can be applied and cured in sea water and suffer no deterioration.The advantages of this system include versatility, relatively low cost, adaptability to continuous monitoring and the possibility of being fitted retrospectively and refitted after repair operations.
Strain gauge performance during fatigue testing
Authors: Middleton J. C. 
Published: October 2008

Strain gauges are used extensively to measure the changes in magnitude and distribution of dynamic stresses during fatigue testing. Over 200 000 fatigue cycles at high strains (4000 ± 2000/u/m) have to be withstood under certain conditions such as when evaluating the performance of heavy vehicle springs. In this work, various types of commercial strain gauges have been evaluated to determine the most appropriate installation for severe applications.The best results were obtained using a constantan metal foil element strain gauge with phenolic glass backing.Tests on heavy vehicle, multi‐leaf, Taperlite springs, manufactured by Tinsley Bridge Limited (formerly BSC Light Products), have demonstrated the suitability of the chosen system and showed that the dynamic stresses remained essentially constant during fatigue testing.
The determination of principal stresses from photoelastic data
Authors: Haake S. J. , Patterson E. A. 
Published: October 2008

AbstractCurrent developments in the automation of photoelastic analysis have enabled the fast and accurate collection of the isochromatic and isoclinic parametersl from photoelastic specimens. Since the isochromatic parameter yields the difference in the principal stresses then a suitable procedure has to be used for their separation. This paper provides a survey of the stress separation techniques available with a view to incorporating the most suitable method into an automated full field polariscope.
Photoelastic stress analysis of reinforced polycarbonate orthodontic brackets
Authors: Rushforth C.D.J. , Bearn D.R. , Aird J.C. 
Published: October 2008

AbstractA photoelastic investigation of the stresses in polycarbonate orthodontic brackets reinforced with stainless steel inserts is reported. Three inserts with different profiles are investigated. They are ranked with respect to the stresses generated at the interfaces of the metallic inserts and the polycarbonate material. Comparison of insert designs is quantified.
A low cost calibration conditioner for dynamic strain gauge measurements
Authors: Iaconis Francesco M. , D'Emilia Giuilio 
Published: October 2008

AbstractA conditioner for dynamic strain measurements that allows for a series of calibration signals with periodic and predefined time occurrence, during the whole period in which the measurements have to be carried out, is presented in this work. The calibration signals, having suitable size ratios between them, allow one to evaluate the linearity of the entire measurement chain.
Measuring simultaneously linear and angular acceleration during a crash
Authors: Bill Bernie 
Published: October 2008

AbstractThe new translational/angular accelerometer presented in this paper consists of a pair of identical preloaded quartz shear elements inside a metal housing. Integrated impedance converters transform the piezoelectric signals to low impedance voltages. The rugged sensor is mounted on the surface of the structure under test by fixing it with four screws. It allows the simultaneous measurement of translational and angular acceleration. Due to its construction, the small and light weight sensor is suited for shock application, e.g. during crashes. An example of linear and angular acceleration acting on a dummy head during a crash is presented.
Investigation of contact stresses of a rotating cam by a digital photoelastic method
Authors: Wang Ming‐Jong , Wang Wei‐Chung 
Published: October 2008

AbstractThe maximum contact shear stresses (MCSS) and their locations of a rotating cam during rise and at a specific rotation speed were sought by a self‐developed digital phototelastic system with added functions of syncronous trigger and continuous image taking. Also found were the MCSS of a camduring rise under static state. The difference between the dynamic and static states were compared and investigated.