bluuebunny/crossref_metadata_2025 huggingface dataset:
Combinatorial and metric properties of Thompson’s group 𝑇
Authors: Burillo José , Cleary Sean , Stein Melanie , Taback Jennifer
Published: October 2008

We discuss metric and combinatorial properties of Thompson’s group

T
T

, including normal forms for elements and unique tree pair diagram representatives. We relate these properties to those of Thompson’s group

F
F

when possible, and highlight combinatorial differences between the two groups. We define a set of unique normal forms for elements of

T
T

arising from minimal factorizations of elements into natural pieces. We show that the number of carets in a reduced representative of an element of

T
T

estimates the word length, that

F
F

is undistorted in

T
T

, and we describe how to recognize torsion elements in

T
T

.
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
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="sigma-summation Underscript i comma j equals 1 Overscript upper N Endscripts a Subscript i j Baseline left-parenthesis x right-parenthesis StartFraction partial-differential squared u Over partial-differential x Subscript i Baseline partial-differential x Subscript j Baseline EndFraction plus u Superscript p Baseline equals 0">

∑

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.
𝐼[𝜔₂] can be the nonstationary ideal on 𝐶𝑜𝑓(𝜔₁)
Authors: Mitchell William
Published: October 2008

We answer a question of Shelah by showing that it is consistent that every member of

I
[

ω
2

]
∩
Cof
⁡
(

ω
1

)

I[\omega _2]\cap \operatorname {Cof}(\omega _1)

is nonstationary if and only if it is consistent that there is a

κ
+

\kappa ^+

-Mahlo cardinal

κ
\kappa

.
Computational topology of equivariant maps from spheres to complements of arrangements
Authors: Blagojević Pavle , Vrećica Siniša , Živaljević Rade
Published: October 2008

The problem of the existence of an equivariant map is a classical topological problem ubiquitous in topology and its applications. Many problems in discrete geometry and combinatorics have been reduced to such a question and many of them resolved by the use of equivariant obstruction theory. A variety of concrete techniques for evaluating equivariant obstruction classes are introduced, discussed and illustrated by explicit calculations. The emphasis is on

D

2
n

D_{2n}

-equivariant maps from spheres to complements of arrangements, motivated by the problem of finding a

4
4

-fan partition of

2
2

-spherical measures, where

D

2
n

D_{2n}

is the dihedral group. One of the technical highlights is the determination of the

D

2
n

D_{2n}

-module structure of the homology of the complement of the appropriate subspace arrangement, based on the geometric interpretation for the generators of the homology groups of arrangements.
The absolutely continuous spectrum of discrete canonical systems
Authors: Fischer Andreas , Remling Christian
Published: October 2008

We prove that if the canonical system

J
(

y

n
+
1

−

y
n

)
=
z

H
n

y
n

J(y_{n+1}-y_n)= zH_ny_n

has absolutely continuous spectrum of a certain multiplicity, then there is a corresponding number of linearly independent solutions

y
y

which are bounded in a weak sense.
No evidence for an evolutionary trade-off between learning and immunity in a social insect
Authors: Alghamdi A , Raine N.E , Rosato E , Mallon E.B
Published: October 2008

The immune response affects learning and memory in insects. Given this and the known fitness costs of both the immune system and learning, does an evolutionary trade-off exist between these two systems? We tested this by measuring the learning ability of 12 bumble-bee (
Bombus terrestris
) colonies in a free-flying paradigm. We then tested their immune response using the zone of inhibition assay. We found a positive relationship between colony learning performance and immune response, that is, fast-learning colonies also show high levels of antimicrobial activity. We conclude that there is no
a priori
reason to demand an evolutionary relationship between two traits that are linked physiologically.
Geodesic flows on semidirect-product Lie groups: geometry of singular measure-valued solutions
Authors: Holm Darryl D , Tronci Cesare
Published: October 2008

The EPDiff equation (or the dispersionless Camassa–Holm equation in one dimension) is a well-known example of geodesic motion on the Diff group of smooth invertible maps (diffeomorphisms). Its recent two-component extension governs geodesic motion on the semidirect product DiffⓈ

, where

denotes the space of scalar functions. This paper generalizes the second construction to consider geodesic motion on DiffⓈ

, where

denotes the space of scalar functions that take values on a certain Lie algebra (e.g.

=

⊗

(3)). Measure-valued delta-like solutions are shown to be momentum maps possessing a dual pair structure, thereby extending previous results for the EPDiff equation. The collective Hamiltonians are shown to fit into the Kaluza–Klein theory of particles in a Yang–Mills field and these formulations are shown to apply also at the continuum partial differential equation level. In the continuum description, the Kaluza–Klein approach produces the Kelvin circulation theorem.
Long-term reciprocation of grooming in wild West African chimpanzees
Authors: Gomes Cristina M , Mundry Roger , Boesch Christophe
Published: October 2008

Humans are well known for their ability to keep track of social debts over extended periods of time, and for their tendency to preferentially cooperate with closely bonded partners. Non-human primates have been shown to cooperate with kin and non-kin, and reciprocate helpful acts. However, there is ongoing debate over whether they keep track of previous interactions and, if so, whether they can do it over extended periods of time, or are constrained to finalize exchanges within a single encounter. In this study, we used 3000 hours of all-day focal follows of wild chimpanzees (Pan troglodytes verus) to investigate whether both females and males reciprocate grooming within a single interaction, throughout the day, or over longer periods of time. We found that grooming was reciprocated more symmetrically when measured on a long-term, rather than on an immediate or short-term basis. Random giving, general allocation of grooming efforts, similarities among individuals and kinship do not appear to explain these highly reciprocal exchanges. Previously collected consecutive focal follows of single individuals revealed that dyads groomed an average of once every 7 days. Our findings strongly suggest that chimpanzees, similar to humans, are able to keep track of past social interactions, at least for a one-week period, and balance services over repeated encounters.
Proton-coupled gating in chloride channels
Authors: Lísal Jiří , Maduke Merritt
Published: October 2008

The physiologically indispensable chloride channel (CLC) family is split into two classes of membrane proteins: chloride channels and chloride/proton antiporters. In this article we focus on the relationship between these two groups and specifically review the role of protons in chloride-channel gating. Moreover, we discuss the evidence for proton transport through the chloride channels and explore the possible pathways that the protons could take through the chloride channels. We present results of a mutagenesis study, suggesting the feasibility of one of the pathways, which is closely related to the proton pathway proposed previously for the chloride/proton antiporters. We conclude that the two groups of CLC proteins, although in principle very different, employ similar mechanisms and pathways for ion transport.
Structure and mechanism of ATP-binding cassette transporters
Authors: Locher Kaspar P
Published: October 2008

ATP-binding cassette (ABC) transporters constitute a large superfamily of integral membrane proteins that includes both importers and exporters. In recent years, several structures of complete ABC transporters have been determined by X-ray crystallography. These structures suggest a mechanism by which binding and hydrolysis of ATP by the cytoplasmic, nucleotide-binding domains control the conformation of the transmembrane domains and therefore which side of the membrane the translocation pathway is exposed to. A basic, conserved two-state mechanism can explain active transport of both ABC importers and ABC exporters, but various questions remain unresolved. In this article, I will review some of the crystal structures and the mechanistic insight gained from them. Future challenges for a better understanding of the mechanism of ABC transporters will be outlined.
Proton-coupled protein transport through the anthrax toxin channel
Authors: Finkelstein Alan
Published: October 2008

Anthrax toxin consists of three proteins (approx. 90 kDa each): lethal factor (LF); oedema factor (OF); and protective antigen (PA). The former two are enzymes that act when they reach the cytosol of a targeted cell. To enter the cytosol, however, which they do after being endocytosed into an acidic vesicle compartment, they require the third component, PA. PA (or rather its proteolytically generated fragment PA
63
) forms at low pH a heptameric β-barrel channel, (PA
63
)
7
, through which LF and OF are transported—a phenomenon we have demonstrated in planar phospholipid bilayers. It might appear that (PA
63
)
7
simply forms a large hole through which LF and OF diffuse. However, LF and OF are folded proteins, much too large to fit through the approximately 15 Å diameter (PA
63
)
7
β-barrel. This paper discusses how the (PA
63
)
7
channel both participates in the unfolding of LF and OF and functions in their translocation as a proton–protein symporter.
The structure of the Na+,K+-ATPase and mapping of isoform differences and disease-related mutations
Authors: Morth J. Preben , Poulsen Hanne , Toustrup-Jensen Mads S , Schack Vivien Rodacker , Egebjerg Jan , Andersen Jens Peter , Vilsen Bente , Nissen Poul
Published: October 2008

The Na+,K+-ATPase transforms the energy of ATP to the maintenance of steep electrochemical gradients for sodium and potassium across the plasma membrane. This activity is tissue specific, in particular due to variations in the expressions of the alpha subunit isoforms one through four. Several mutations in alpha2 and 3 have been identified that link the specific function of the Na+,K+-ATPase to the pathophysiology of neurological diseases such as rapid-onset dystonia parkinsonism and familial hemiplegic migraine type 2. We show a mapping of the isoform differences and the disease-related mutations on the recently determined crystal structure of the pig renal Na+,K+-ATPase and a structural comparison to Ca2+-ATPase. Furthermore, we present new experimental data that address the role of a stretch of three conserved arginines near the C-terminus of the alpha subunit (Arg1003–Arg1005).
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.
Forearm vascular responses to serotonin are not mediated by products of cyclooxygenase
Authors: NUGENT A. G. , McGURK C. , JOHNSTON G. D.
Published: October 2008

The involvement of cyclooxygenase‐derived substances in the forearm arteriolar responses to serotonin was determined in 10 healthy male volunteers. Serotonin was infused in five incremental doses (0.003–30 μg min‐1) for 2 min each into the brachial artery of the non‐dominant forearm. Forearm blood flow (FBF) responses to each dose were measured by strain‐gauge venous occlusion plethysmography. The cyclooxygenase inhibitor indomethacin (100mg) was administered orally following the serotonin infusions. After 90 min the serotonin infusions were repeated and FBF responses measured. Serotonin caused a biphasic response with vasodilatation occurring at low doses (0.003‐3 μg min‐1, P < 0.01) and vasoconstriction occurring at the highest dose (P < 0.01). There was no significant difference in vascular response to serotonin following cyclooxygenase inhibition. In conclusion, cyclooxygenase products are not involved in the forearm vascular responses to serotonin in healthy human subjects.
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.
MEASUREMENT OF NON‐UNIFORM BI‐AXIAL RESIDUAL STRESSES BY THE HOLE DRILLING METHOD
Authors: BATHGATE R. G.
Published: October 2008

The hole drilling method is used to evaluate bi‐axial residual stresses varying with depth. Equations with experimentally determined calibration constants, given here for light‐alloys, relate residual stresses to strain relaxations as the hole is drilled. Accuracy and limitations are assessed by application to known stress conditions. The method can be used on large structures and in field conditions.
MEASUREMENT OF TRANSIENT THERMAL PLASTIC STRAINS
Authors: DECHAENE R. , De COCK J. , De CALUWE M.
Published: October 2008

Plastic strains during welding are measured by the moire method
APPLICATION OF PHOTOHOLOELASTICITY TO FROZEN TWO‐DIMENSIONAL MODELS WITH EXTENSIONS TO THREE‐DIMENSIONAL ANALYSIS
Authors: HOVANESIAN JOSEPH DER
Published: October 2008

Hologram interferometry was extended to the study of stresses in fixed two‐dimensional photoelastic models. Application to three‐dimensional slice analyses was explored qualitatively. The process involved a double exposure hologram, whereby the hologram of the model was exposed before and after annealing. Reconstruction of the processed hologram displayed isochtomatic and isopachic interference patterns.
MODEL ANALYSIS OF THE ROYAL ALBERT BRIDGE, SALTASH
Authors: WHITBREAD J. E.
Published: October 2008

This article describes some of the history and construction of the Royal Albert Bridge at Saltash, and Isambard Kingdom Brunei's considerations in its design. Modern requirements for the bridge are discussed and a recent investigation including model analysis resulting in structural modification to the bridge for modern traffic is described.
STRESS DISTRIBUTION IN A STATOR VANE UNDER BENDING
Authors: DURELLI A. J. , PARKS V. J. , LEE HAN‐CHOW
Published: October 2008

The stress distribution on the surface of a stator vane loaded statically as a cantilever has been obtained by means of brittle coatings, strain gauges and three‐dimensional photoelasticity. A metal prototype was available for the determinations and from this an epoxy model was made by casting. The combination of methods used suggests the most efficient way of stress analyzing this type of structure.
THE MOIRÉ EFFECT APPLIED TO EXPERIMENTAL STRESS ANALYSIS
Authors: LUXMOORE A. R.
Published: October 2008

This paper summarises the applications of the moire effect to stress analysis problems and enumerates its advantages over the conventional grid techniques.
PREPARING A METAL SPECIMEN FOR THE INSTALLATION OF A BONDED RESISTANCE STRAIN GAUGE
Authors: COUTTS J. A. , COOMBS A. J.
Published: October 2008

A procedure for preparing a metal surface for accepting of a strain gauge is described in 8 pictures with a short explanatory text.
VISIT TO THE SOVIET UNION BY BRITISH WORKING SUB‐GROUP C
Authors: GALL M. H. W.
Published: October 2008

Soviet manufacture is reported of micro‐wire for strain gauges, resistors and instruments, and of printed resistors for high‐precision potentiometors.
A DIRECT READING FLEXIBLE STRAIN GAUGE
Authors: YENDELL M. J.
Published: October 2008

A scale and a vernier, which are photographed on two strips of copying film on a flexible high‐stability polyester backing, can freely slide over each other so that, if affixed to the test piece at opposite ends, they form a strain gauge of minimal stiffness measuring up to 12% strain with a sensitivity of 0.1% strain. Effects of curvature are taken into account by calculation.
TRIANGULAR AND v 2 GRATINGS FOR THE MOIRÉ TECHNIQUE
Authors: FIDLER R. , LAW I. , NURSE P.
Published: October 2008

Methods for constructing two new types of grating for the moiré technique are described, their use is illustrated in application to a simple beam, and the range of measurable strains is established. In certain circumstances the use of these gratings presents a means of accurate analysis without recourse to elaborate equipment.
On the initial balance of Wheatstone bridges
Authors: BAZERGUI A.
Published: October 2008

Three commonly used methods of bridge balancing are analysed. Relations and graphs are presented for ready determination of the necessary resistances and potentiometers. A circuit with a potentiometer parallel to two bridge arms and with a single limiting resistor between apex and potentiometer slider appears to be the simplest and most economical; it also gives a comparatively small error.
Carbon radio resistors as pressure transducers
Authors: FROUD G. R.
Published: October 2008

This article presents a theoretical analysis of the action of carbon radio resistors as pressure transducers and shows how, from practical measurements, gauge factors can be predicted without the necessity to calibrate. Practical measurements agree well with predicted values, and for large numbers of expendable gauges, considerable time saving with little loss of accuracy can be obtained by use of predicted gauge factors.
Casting of photoelastic models for centrifugal pump impellers
Authors: OLLERTON E. , RELLE A. J.
Published: October 2008

A technique has been developed for the manufacture of epoxy resin castings of centrifugal pump impellers for use in photoelastic work. The castings are produced in one piece with the aid of silicone rubber corepieces and aluminium moulds, and the method of producing reliable castings is described in detail.
Design and development of Manganin and other wire sensors together with a resistance strain gauge transducer for use at pressures up to 200000 lbf/in2(1.38 GN/m2)
Authors: BIRKS A. W. , GALL C. A.
Published: October 2008

The design and development of Manganin wire sensors for use at pressures up to 200 000 lbf/in2(1.38 GN/m2) is described and data presented for an alternative wire, Zeranin. A brief description of suitable bridge and digital read–out systems is given together with the design of a resistance strain gauge transducer suitable for control applications.
Balancing techniques for strain gauge bridges
Authors: BAKER K. M.
Published: October 2008

Four common methods of adjusting the resistive balance of a strain gauge bridge installation are described and compared. Effects on gauge factor and temperature stability are discussed and formulae are presented for the calculation of possible errors.
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.
Birefringence in inhomogeneous stress fields
Authors: BROWN G. M.
Published: October 2008

The propagation of polarised light through a birefringent medium subjected to an inhomogeneous stress field in the direction of propagation, is usually described in terms of Neumann's differential equations, the Poincaré sphere, or 2times2 complex transformation matrices. A comparative treatment of these three methods is presented.
Calibration of equidensity lines
Authors: FRIEDRICH G.
Published: October 2008

A method is presented for the calibration of equidensity ‘lines’ produced from conventional fringe patterns by the use of a special Agfa‐Gevaert film. Photoelasticity is an important area of application.
Elastostatics of a cubic box subjected to concentrated loads
Authors: DURELLI A. J. , PAVLIN V. , BÜHLER‐VIDAL J.O. , OME G.
Published: October 2008

This paper deals with the experimental strain, stress and deflection analysis of a cubic box subjected to concentrated loads applied at the centre of two opposite faces. The ratio between the inside span and the wall thickness varied between approximately 5 and 14. All corners had circular fillets. The experimental analysis was conducted using mechanical and electrical strain gauges and brittle coatings. Results, given parametrically by means of a family of curves representing normalized stresses, are applicable to boxes of any size, made of any elastic materials, provided the wall thickness falls within the investigated range. Some results obtained using the theory of structures approach are included for comparison purposes and presented in a form useful to designers.
The new Industrial Technologies and the case of Strain Measurement
Authors: COUTTS J. A.
Published: October 2008

Over the last ten years the Department of Industry and its predecessors have sponsored four Industrial Technologies. A case is made out for a fifth based on the concept of producing a component which will do its job effectively by coordinating all the stages involved in its production. To do this a better supply of specialist information across subject boundaries is recommended. A close parallel is drawn with the development of Tribology as a subject.
Application of moiré technique in the stress analysis of cutting tools
Authors: CHANDRASEKARAN H. , NAGARAJAN R. , PADMANABHA K. N.
Published: October 2008

Knowledge of the stress field in cutting tools is necessary for their strength evaluation. However, the experimental analysis of stresses in cutting tools during machining poses a number of problems in view of the steep stress gradient present. Photo‐elasticity and the ‘built‐up tool’ methods are the common techniques used for this purpose. In the present paper results on the stresses in cutting tools obtained during actual machining through the successful application of the transmitted moiré technique, are presented. In these experiments transparent epoxy tools carrying moiré gratings were used to machine commercial lead alloy at low speeds. The tool rake angle was varied. The effectiveness of moiré method, basically a displacement analysis technique, in providing useful data on tool stresses comparable with the other direct stress analysis techniques such as photo‐elasticity is also discussed in the paper.
Brittle coating studies on fibrous composites
Authors: Chaturvedi S. K. , Agarwal B. D.
Published: October 2008

A brittle coating stress analysis technique applicable to orthotropic materials has been developed. The technique has been applied to a unidirectional glass fibre reinforced epoxy. Its behaviour has been studied under uniaxial and biaxial stress fields using cantilever beam specimens and circular disc specimens under diametral compression. Fibre orientation in the specimens has been varied. In each case it has been observed that the cracks represent the direction of principal strains in the specimen material and not the direction of principal stresses. Application of brittle coating techniques has been suggested to establish the direction and magnitude of principal stresses and strains at every point in a problem with unknown stresses and strains.
Deflection measurement of a cantilever plate by holographic interferometry
Authors: KHADAKKAR A. G. , NARAYANAN R. , IYER NAGESH R.
Published: October 2008

Holographic interferometry has been applied to the analysis of a square cantilever plate subjected to a corner load. Whole field deflections were obtained from a reconstructed hologram and compared with theoretical results. Good agreement was obtained indicating thereby the precision with which even complicated structural engineering problems can be solved using the holographic technique.
DIY strain gauge transducers (Part 1)
Authors: POPLE J.
Published: October 2008

Although ‘commercial’ transducers are readily available it is sometimes necessary to build a transducer by bonding gauges to part of an existing structure, eg. a tension link or a propeller shaft.
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.
Effects of self heating when using a continuous bridge voltage for strain gauging epoxy models
Authors: LITTLE E. G.
Published: October 2008

One source of concern when strain gauging epoxy materials, is that if the gauges are continuously energised at high power densities, then the heat generated by the strain gauges will cause large apparent strains and will reduce the modulus of the underlying material. The magnitude and significance of the heating effect are discussed and methods of reducing this effect are indicated.
On the correction of residual stress measurements obtained using the centre‐hole method
Authors: Scaramangas A. A. , Goff R. F. D. Porter , Leggatt R. H.
Published: October 2008

Significant errors in interpreting the results of the centre‐hole technique may arise where test conditions deviate from a uniform uniaxial low‐level stress field. This paper demonstrates that where the stress field varies linearly with depth, the as‐measured stress represents the stress at one‐quarter hole depth. In cases where surface preparation for strain gauging has induced residual stress or where stress levels are sufficiently high to induce plasticity during hole forming, simple formulae are proposed to correct for these effects.
A note on Moiré gratings by a stacked card method
Authors: Subramanian G.
Published: October 2008

An unusual method is described in which a stack of alternating plain and painted cards forms gratings for Moiré applications. It is quite simple and versatile so that almost anyone may adopt it with ease and a minimum of expertise.
Annealing polycarbonate sheets
Authors: Pappalettere Carmine
Published: October 2008

An annealing cycle for polycarbonate sheets is proposed in this paper. Tests carried out on 0.75–3.00 mm thick sheets show the good reliability of the technique. Further confirmation can be found in practical applications reported in other papers.
The use of a microdensitometer in photoelastic analyses
Authors: Kenny B. , Patterson E. A.
Published: October 2008

The use of an automatic recording microdensitometer in conjunction with a fringe multiplying polariscope for analysing small portions of slices from frozen stress photoelastic models is described in detail. The method is used to find the load distribution in the threads of a 30 mm ISO nut and bolt model. The accuracy is discussed and shown to be comparable to that of conventional photoelastic techniques.
The behaviour of a cylindrical vessel loaded through a series of internal diaphragms—an experimental study
Authors: Motashar Faisal A. , Tooth Alwyn S.
Published: October 2008

The model work presented in this paper was stimulated by investigations carried out on 3.7 m diameter horizontal cylindrical vessels used as oily water separators. In these, internal diaphragms were installed to provide support for the horizontal sand filter bed running the full length of the vessel. By means of four cylindrical plastic models two different designs for the diaphragm are considered. On the basis of strain gauge investigations, conclusions are drawn which should provide a design approach for these components whereby certain peak stresses can be avoided.
Optimum shapes of inner and outer boundaries of circular rings under internal diametral tension
Authors: Rajaiah K. , Bose M. S. C. , Palse A. B.
Published: October 2008

Optimisation of inner and outer boundaries of circular rings under internal diametral tension using two dimensional photoelasticity is presented. It is shown that, when shape optimisation of only one of the two boundaries in the field is carried out, there is an increase in the stresses on the other boundary. However, optimisation of both the boundaries is found to be beneficial with significant reduction in stress concentration factor and weight.
Characteristic angle, light intensity and their correlation to wavelength in three dimensional photoelastic media
Authors: Issa S. S. , Marie I.
Published: October 2008

The interaction of the photoelastic parameters, the normalised light intensity In the characteristic angle ψ, and their link to the stress state parameters, the ratio of bending and direct stresses P and the angle of divergence θ of the stress components σM and σN have been examined by employing different wavelengths. The analysis of the experimental data shows that the correlation diagrams of these parameters demonstrate similar characteristic curves. Measurements also show a preferable range of wavelength within which the wavelength of light source should be selected. So far the results are valid for thin plates, thin shells of rotationally symmetric conditions and similar structures.