bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanics and energetics of level walking with powered ankle exoskeletons
Authors: Sawicki Gregory S. , Ferris Daniel P.
Published: April 2008

Robotic lower limb exoskeletons that can alter joint mechanical power output are novel tools for studying the relationship between the mechanics and energetics of human locomotion. We built pneumatically powered ankle exoskeletons controlled by the user's own soleus electromyography (i.e. proportional myoelectric control) to determine whether mechanical assistance at the ankle joint could reduce the metabolic cost of level, steady-speed human walking. We hypothesized that subjects would reduce their net metabolic power in proportion to the average positive mechanical power delivered by the bilateral ankle exoskeletons. Nine healthy individuals completed three 30 min sessions walking at 1.25 m s–1 while wearing the exoskeletons. Over the three sessions, subjects' net metabolic energy expenditure during powered walking progressed from +7% to –10% of that during unpowered walking. With practice, subjects significantly reduced soleus muscle activity (by ∼28% root mean square EMG, P<0.0001) and negative exoskeleton mechanical power (–0.09 W kg–1 at the beginning of session 1 and –0.03 W kg–1 at the end of session 3; P=0.005). Ankle joint kinematics returned to similar patterns to those observed during unpowered walking. At the end of the third session, the powered exoskeletons delivered ∼63% of the average ankle joint positive mechanical power and ∼22% of the total positive mechanical power generated by all of the joints summed (ankle, knee and hip) during unpowered walking. Decreases in total joint positive mechanical power due to powered ankle assistance (∼22%) were not proportional to reductions in net metabolic power (∼10%). The `apparent efficiency' of the ankle joint muscle–tendon system during human walking (∼0.61) was much greater than reported values of the `muscular efficiency' of positive mechanical work for human muscle (∼0.10–0.34). High ankle joint `apparent efficiency' suggests that recoiling Achilles' tendon contributes a significant amount of ankle joint positive power during the push-off phase of walking in humans.
Duelling aphids: electrical penetration graphs reveal the value of fighting for a feeding site
Authors: Morris Genevieve , Foster William A.
Published: April 2008

Horned aphids (Cerataphidini) fight each other for access to feeding sites on leaves. An attacker attempts to force another aphid to abandon its feeding site; the victor then appears to insert its stylets into the site relinquished by the loser. This study used electrical penetration graph (EPG) recordings of Astegopteryx pallida (Van der Goot) individuals to pinpoint the benefits of fighting. We show that victors take significantly less time to commence feeding in the phloem, measured from the start of probing with their stylets, compared with aphids that initiate a new or discover an abandoned site: 9.0 versus 22.9 min, respectively. We also recorded the behaviour of aphids unencumbered with the wire necessary for EPG recordings. Those adult aphids that acquired a feeding site through fighting commenced feeding on average 20 min earlier than those that did not, taking into account the time spent searching and fighting as well as probing. This study clearly establishes that horned aphids use the exact feeding site vacated by another individual and that the benefit they gain is rapid access to the phloem– more rapid, indeed, than has previously been recorded in any aphid.
Reptilian uncoupling protein: functionality and expression in sub-zero temperatures
Authors: Rey Benjamin , Sibille Brigitte , Romestaing Caroline , Belouze Maud , Letexier Dominique , Servais Stéphane , Barré Hervé , Duchamp Claude , Voituron Yann
Published: April 2008

Here we report the partial nucleotide sequence of a reptilian uncoupling protein (repUCP) gene from the European common lizard (Lacerta vivipara). Overlapping sequence analysis reveals that the protein shows 55%, 72% and 77% sequence homology with rat UCP1, UCP2 and UCP3, respectively,and 73% with bird and fish UCPs. RepUCP gene expression was ubiquitously detected in 4°C cold-acclimated lizard tissues and upregulated in muscle tissues by a 20 h exposure to sub-zero temperatures in a supercooling state or after thawing. In parallel, we show an increase in the co-activators,peroxisome proliferator-activated receptor γ coactivator-1α(PGC-1α) and peroxisome proliferator-activated receptors (PPAR), mRNA expression, suggesting that the mechanisms regulating UCP expression may be conserved between mammals (endotherms) and reptiles (ectotherms). Furthermore,mitochondria extracted from lizard skeletal muscle showed a guanosine diphosphate (GDP)-sensitive non phosphorylating respiration. This last result indicates an inhibition of extra proton leakage mediated by an uncoupling protein, providing arguments that repUCP is functional in lizard tissues. This result is associated with a remarkable GDP-dependent increase in mitochondrial endogenous H2O2 production. All together, these data support a physiological role of the repUCP in superoxide limitation by lizard mitochondria in situations of stressful oxidative reperfusion following a re-warming period in winter.
Lower-limb biomechanics during stair descent: influence of step-height and body mass
Authors: Spanjaard M. , Reeves N. D. , van Dieën J. H. , Baltzopoulos V. , Maganaris C. N.
Published: April 2008

The aim of the present study was to examine the biomechanics of the lower limb during stair descent and the effects of increasing demand in two ways: by increasing step-height and by increasing body mass. Ten male subjects walked down a four-step staircase, the height of which could be altered. The step-heights were: standard (17 cm), 50% decreased, 50% increased and 75%increased. At the standard height, subjects also walked down wearing a weighted jacket carrying 20% extra body mass. Lower limb kinematics and kinetics were determined using motion capture and ground reaction forces. Also measured were gastrocnemius medialis (GM) muscle electromyography and GM muscle fascicle length using ultrasonography. GM muscle fascicles actively shortened during the touch-down phase of stair descent in all conditions,while the muscle–tendon complex (MTC), as calculated from the knee and ankle joint kinematics, lengthened. The GM muscle fascicles shortened more when step-height was increased, which corresponded to the increase in ankle joint moment. Increased body mass did not alter the ankle or knee joint moment in the first contact phase of a step down; due to a change in strategy, the trailing leg, instead of the leading leg, supported the extra mass. Hence, the amount of GM muscle fascicle shortening, during the touch-down phase, also did not change with added body mass. Our results suggest that the increase in joint moments is related to the amount of fascicle shortening, which occurs whilst the MTC is lengthening, thereby stretching the elastic tendinous tissues.
Role of the PGC-1 family in the metabolic adaptation of goldfish to diet and temperature
Authors: LeMoine Christophe M. R. , Genge Christine E. , Moyes Christopher D.
Published: April 2008

In mammals, the peroxisome proliferator-activated receptor (PPAR) γcoactivator-1 (PGC-1) family members and their binding partners orchestrate remodelling in response to diverse challenges such as diet, temperature and exercise. In this study, we exposed goldfish to three temperatures (4, 20 and 35°C) and to three dietary regimes (food deprivation, low fat and high fat) and examined the changes in mitochondrial enzyme activities and transcript levels for metabolic enzymes and their genetic regulators in red muscle, white muscle, heart and liver. When all tissues and conditions were pooled, there were significant correlations between the mRNA for the PGC-1 coactivators (both α and β) and mitochondrial transcripts (citrate synthase), metabolic gene regulators including PPARα, PPARβ and nuclear respiratory factor-1 (NRF-1). PGC-1β was the better predictor of the NRF-1 axis, whereas PGC-1α was the better predictor of the PPAR axis(PPARα, PPARβ, medium chain acyl CoA dehydrogenase). In contrast to these intertissue/developmental patterns, the response of individual tissues to physiological stressors displayed no correlations between mRNA for PGC-1 family members and either the NRF-1 or PPAR axes. For example, in skeletal muscles, low temperature decreased PGC-1α transcript levels but increased mitochondrial enzyme activities (citrate synthase and cytochrome oxidase) and transcripts for COX IV and NRF-1. These results suggest that in goldfish, as in mammals, there is a regulatory relationship between (i) NRF-1 and mitochondrial gene expression and (ii) PPARs and fatty acid oxidation gene expression. In contrast to mammals, there is a divergence in the roles of the coactivators, with PGC-1α linked to fatty acid oxidation through PPARα, and PGC-1β with a more prominent role in mediating NRF-1-dependent control of mitochondrial gene expression, as well as distinctions between their respective roles in development and physiological responsiveness.
Functional and morphological plasticity of crocodile (Crocodylus porosus) salt glands
Authors: Cramp Rebecca L. , Meyer Edward A. , Sparks Nicole , Franklin Craig E.
Published: April 2008

The estuarine crocodile, Crocodylus porosus, inhabits both freshwater and hypersaline waterways and maintains ionic homeostasis by excreting excess sodium and chloride ions via lingual salt glands. In the present study, we sought to investigate the phenotypic plasticity, both morphological and functional, in the lingual salt glands of the estuarine crocodile associated with chronic exposure to freshwater (FW) and saltwater(SW) environments. Examination of haematological parameters indicated that there were no long-term disruptions to ionic homeostasis with prolonged exposure to SW. Maximal secretory rates from the salt glands of SW-acclimated animals (100.8±14.7 μmol 100 g–0.7 body mass h–1) were almost three times greater than those of FW-acclimated animals (31.6±6.2 μmol 100 g–0.7 body mass h–1). There were no differences in the mass-specific metabolic rate of salt gland tissue slices from FW- and SW-acclimated animals(558.9±49.6 and 527.3±142.8 μl O2g–1 h–1, respectively). Stimulation of the tissue slices from SW-acclimated animals by methacholine resulted in a 33%increase in oxygen consumption rate. There was no significant increase in the metabolic rate of tissues from FW-acclimated animals in response to methacholine. Morphologically, the secretory cells from the salt glands of SW-acclimated animals were larger than those of FW-acclimated animals. In addition, there were significantly more mitochondria per unit volume in secretory tissue from SW-acclimated animals. The results from this study demonstrate that the salt glands of C. porosus are phenotypically plastic, both morphologically and functionally and acclimate to changes in environmental salinity.
Aldehyde-encapsulating liposomes impair marine grazer survivorship
Authors: Buttino Isabella , De Rosa Giuseppe , Carotenuto Ylenia , Mazzella Marialuisa , Ianora Adrianna , Esposito Francesco , Vitiello Valentina , Quaglia Fabiana , La Rotonda Maria Immacolata , Miralto Antonio
Published: April 2008

In the last decade, there has been an increased awareness that secondary metabolites produced by marine diatoms negatively impact the reproductive success of their principal predators, the copepods. Several oxylipins,products of the enzymatic oxidation of fatty acids, are produced when these unicellular algae are damaged, as occurs during grazing. In the past, the dinoflagellate Prorocentrum minimum, which does not produce the oxylipin 2-trans,4-trans-decadienal (DD), has been used as a live carrier to calculate daily ingestion rates of this molecule by copepod crustaceans. However, since the interaction between oxylipins and live carriers is unknown, the question as to how much and for how long ingestion of these molecules affects copepod reproduction remains a critical point to understanding the functional role of such compounds at sea. In the investigation presented here we used giant liposomes (∼7 μm) as a delivery system for the oxylipin DD, prepared in the same size range as copepod food and containing known amounts of DD. The aim of this work was to relate the ingestion of DD to the reproductive failure of the copepods Temora stylifera and Calanus helgolandicus. Liposomes were very stable over time and after 10 days of feeding, liposomes encapsulating DD reduced egg hatching success and female survival with a concomitant appearance of apoptosis in both copepod embryos and female tissues. Concentrations of DD inducing blockage were one order of magnitude lower that those used in classical feeding experiments demonstrating that liposomes are a useful tool to quantitatively analyze the impact of toxins on copepods.
Retinal processing and opponent mechanisms mediating ultraviolet polarization sensitivity in rainbow trout (Oncorhynchus mykiss)
Authors: Ramsden Samuel D. , Anderson Leslie , Mussi Martina , Kamermans Maarten , Hawryshyn Craig W.
Published: April 2008

A number of teleost fishes have photoreceptor mechanisms to detect linearly polarized light. We studied the neuronal mechanism underlying this ability. It was found that a polarized signal could be detected in rainbow trout(Oncorhynchus mykiss) both in the electroretinogram (ERG) and in the compound action potential (CAP) measured in the optic nerve, indicating a strong retinal contribution to the processing of polarized light. The CAP recordings showed a W-shaped sensitivity curve, with a peak at 0°, 90°and 180°, consistent with processes for both vertical and horizontal orientation. By contrast, the ERG recordings reveal a more complex pattern. In addition to the peaks at 0°, 90° and 180°, two additional peaks appeared at 45° and 135°. This result suggests a specialized contribution of the outer retina in the processing of polarized light. The spectral sensitivity of the mechanisms responsible for these intermediate peaks was studied using chromatic adaptation. Here we show that long wavelength-sensitive (LWS) cone mechanism adaptation shifted the intermediate peaks towards 90°, whereas ultraviolet-sensitive (UVS) cone mechanism adaptation shifted the peaks away from 90° towards either 0° or 180°. These results provide further confirmation that the 90° peak is dominated by the LWS cone mechanism and the 0° and 180° peaks are dominated by the UVS cone mechanism. In addition, a pharmacological approach was used to examine the retinal neural mechanisms underlying polarization sensitivity. The effect of blocking negative feedback from horizontal cells to cones on the ERG was studied by making intraocular injections of low doses of cobalt, known to block this feedback pathway. It was found that the intermediate peaks seen in the ERG polarization sensitivity curves were eliminated after application of cobalt, suggesting that these peaks are due to outer retinal inhibition derived from feedback of horizontal cells onto cones. A simple computational model was developed to evaluate these results. The model consists of opponent and non-opponent processing elements for the two polarization detectors. This model provides a first approximation analysis suggesting that opponent processing occurs in the outer retina for polarization vision. Although it seems that polarization vision uses a slightly more complicated coding scheme than colour vision, the results presented in this paper suggest that opponent and non-opponent channels process polarization information.
Multimarket Facility Network Design with Offshoring Applications
Authors: Lu Lauren Xiaoyuan , Van Mieghem Jan A.
Published: April 2008

Moving production to low-wage countries may reduce manufacturing costs, but it increases logistics costs and is subject to foreign trade barriers, among others. This paper studies a manufacturer's multimarket facility network design problem and investigates the offshoring decision from a network capacity investment perspective. We analyze a firm that manufactures two products to serve two geographically separated markets using a common component and two localized final assemblies. The common part can be transported between the two markets that have different economic and demand characteristics. Two strategic network design questions arise naturally: (1) Should the common part be produced centrally or in two local facilities? (2) If a centralization strategy is adopted, in which market should the facility be located? We present a transportation cost threshold that captures costs, revenues, and demand risks, and below which centralization is optimal. The optimal location of commonality crucially depends on the relative magnitude of price and manufacturing cost differentials but also on demand size and uncertainty. Incorporating scale economies further enlarges the centralization's optimality region.
Bounded Rationality in Newsvendor Models
Authors: Su Xuanming
Published: April 2008

Many theoretical models adopt a normative approach and assume that decision makers are perfect optimizers. In contrast, this paper takes a descriptive approach and considers bounded rationality, in the sense that decision makers are prone to errors and biases. Our decision model builds on the quantal choice model: While the best decision need not always be made, better decisions are made more often. We apply this framework to the classic newsvendor model and characterize the ordering decisions made by a boundedly rational decision maker. We identify systematic biases and offer insight into when overordering and underordering may occur. We also investigate the impact of these biases on several other inventory settings that have traditionally been studied using the newsvendor model as a building block, such as supply chain contracting, the bullwhip effect, and inventory pooling. We find that incorporating decision noise and optimization error yields results that are consistent with some anomalies highlighted by recent experimental findings.
Determinants of Firms' Backward- and Forward-Looking R&D Search Behavior
Authors: Chen Wei-Ru
Published: April 2008

This study develops and operationalizes a behavioral forward-looking search model by incorporating prospect theory, organizational risk literature, and the logic of the behavioral theory of the firm. With recognition of the bounded rationality of decision makers and the goal-directed, rule-based nature of organizations, this model suggests that a comparison between firms' performance expectation and performance target translates the cognitive representation of the firms' future into their subsequent actions. By examining the research and development (R&D) expenditures of U.S. manufacturing firms from 1980 to 2001, this study explores how performance, aspirations, expectations, and slack affect decision making about firms' R&D search investments. The findings show that both performance feedback and performance prospect are important determinants of firms' search behavior after controlling for firm, industry, and time effects. In addition, backward- and forward-looking determinants have interactive effects on search behavior. Firms' problem-driven search activity further increases when firms feel unlikely to achieve the performance target for another year. In contrast, search intensity is reduced when firms expect to improve their performance from an underperforming situation to an outperforming situation. The findings suggest that future research on performance feedback and experiential learning should also consider the effect of forward-looking prospects on firm behavior.
Fast-Track Aassessment Clinic: Selection of Patients for a One-Stop Hip Assessment Clinic
Authors: Johnson SA , Kalairajah Y , Moonot P , Steele N , Field RE
Published: April 2008

INTRODUCTION

The fast-track assessment clinic (FTAC) is a process to select patients who are very likely to require primary total hip replacement. Selected patients can then be seen in a one-off clinic reducing the number of hospital visits, cost to primary care trusts and delay between referral and treatment.

PATIENTS AND METHODS

Fifty patients on the waiting list for hip replacement were analysed to see if there were common parameters that led to their inclusion. From these data, fast-track selection criteria (FTSCs) were generated. These FTSCs were used to make a dual comparison of outcomes between 52 patients seen in a traditional clinic. Finally, a pilot study was conducted in which patients fulfilling FTSCs were seen in a designated clinic.

RESULTS

An Oxford hip score (OHS) of 34 and above combined with severe loss of joint space, severe marginal osteophytes, or both was common to most patients on the waiting list (84%). FTSCs correctly predicted the outcome of the orthopaedic clinic in 38 patients out of a total of 52. During the pilot stage, positive FTSCs were shown to have a positive predictive value of 92% for joint replacement being carried out and a negative predictive value of 46%.

CONCLUSIONS

An OHS of 34 or above combined with complete loss of joint space and/or severe marginal osteophyte formation can be used to select patients who are very likely to need total hip replacement. These patients can be seen in a clinic that combines assessment of surgical indication with medical fitness for surgery.
Implementation of and Compliance with NICE Guidelines in the Secondary Prevention of Osteoporotic Fractures in Postmenopausal Women
Authors: Javid KS , Thien A , Hill R
Published: April 2008

Osteoporosis affects more than 1.2 million women in England and Wales. Hip fractures are associated with increased mortality. The total cost of treating osteoporotic fractures in postmenopausal women is expected to rise to £2.1 billion by 2010. The National Institute for Health and Clinical Excellence (NICE) has issued guidelines for the secondary prevention of osteoporotic fractures in postmenopausal women. The objective of this study was to review the NICE guidelines and to assess the implementation of and compliance with these guidelines in a district general hospital.
The ANKLe Score: An Audit of Otolaryngology Emergency Clinic Record Keeping
Authors: Dexter Sara C , Hayashi Daichi , Tysome James R
Published: April 2008

INTRODUCTION

Accurate and legible medical records are essential to good quality patient care. Guidelines from The Royal College of Surgeons of England (RCSE) state the content required to form a complete medical record, but do not address legibility. An audit of otolaryngology emergency clinic record keeping was performed using a new scoring system.

PATIENTS AND METHODS

The Adjusted Note Keeping and Legibility (ANKLe) score was developed as an objective and quantitative method to assess both the content and legibility of case notes, incorporating the RCSE guidelines. Twenty consecutive otolaryngology emergency clinic case notes from each of 7 senior house officers were audited against standards for legibility and content using the ANKLe score. A proforma was introduced to improve documentation and handwriting advice was given. A further set of 140 notes (20 notes for each of the 7 doctors) was audited in the same way to provide feedback.

RESULTS

The introduction of a proforma and advice on handwriting significantly increased the quality of case note entries in terms of content, legibility and overall ANKLe score.

CONCLUSIONS

Accurate note keeping can be improved by the use of a proforma. The legibility of handwriting can be improved using simple advice. The ANKLe score is an objective assessment tool of the overall quality of medical note documentation which can be adapted for use in other specialties.
Gastric Cancer Surgery – A Balance of Risk and Radicality
Authors: Lamb Peter , Sivashanmugam T , White Martin , Irving Mark , Wayman John , Raimes Simon
Published: April 2008

INTRODUCTION

The aim of this study was to determine whether tailoring the extent of resection would allow radical gastric cancer surgery to be performed safely in a UK population.

PATIENTS AND METHODS

A total of 180 consecutive patients (median age 70 years; male:female ratio 2:1) undergoing resection for gastric adenocarcinoma with curative intent were studied. Extent of lymphadenectomy was based upon pre-operative and intra-operative staging, and balanced against the patient's age and fitness.

RESULTS

In the study group, 83 patients underwent subtotal or distal partial gastrectomy and 97 patients underwent total or proximal partial gastrectomy. Operative procedures were: D1 lymphadenectomy (n = 62); modified (spleen and pancreas preserving) D2 lymphadenectomy (n = 73); D2 lymphadenectomy (n = 42); and extended resection (n = 3). TNM classification was: stage 1 (n = 45); stage 2 (n = 37); stage 3 (n = 61); and stage 4 (n = 37). Of the patients, 48 developed postoperative complications including 17 patients with a major surgical complication. The in-hospital mortality was 1.7% (3 of 180). Predicted mortality according to POSSUM and P-POSSUM was 21.4% and 7.8%, respectively. Disease-specific 5-year survival according to stage was 85.4%, 64.2%, 33.3%, and 6.9%.

CONCLUSIONS

By tailoring the extent of resection and balancing risk and radicality, gastric cancer surgery can be performed with low mortality in Western patients.
Living-Unrelated Donor Renal Transplantation: An Alternative to Living-Related Donor Transplantation?
Authors: Ahmad Nadeem , Ahmed Kamran , Khan Mohammad Shamim , Calder Francis , Mamode Nizam , Taylor John , Koffman Geoff
Published: April 2008

INTRODUCTION

An increasing number of living-unrelated, kidney donor transplants are being performed in our unit. We present a comparison of living-unrelated (LURD) and living-related donor (LRD) renal transplant outcomes and analyse influencing factors.

PATIENTS AND METHODS

We retrospectively analysed the outcome of all living-donor renal transplants performed at our centre from 1993 to 2004. The parameters studied included patient and graft survival, functioning status of grafts (determined by estimated GFR) at last follow-up and any rejection episodes. Multivariate analysis was performed for recipient and donor age, ethnicity, HLA matching and re-transplants.

RESULTS

A total of 322 live donor kidney transplants (LRD, n = 261; LURD, n = 61) were carried out over this period. Mean recipient age was 28 ± 16 years in the LRD group and 48 ± 12 years in LURD, while mean age of the donors was 43 ± 11 years and 48 ± 10 years, respectively. Caucasians constituted 80% of all the living donors. Amongst LRD, parents were the commonest (58%) donors followed by siblings (35%). In LURD, 80% were spouses. A total of 33 grafts failed, 30 in LRD (11%) and 3 in LURD (5%). Thirteen patients died, 11 (4.2%) in LRD (7 with functioning graft) and 2 (3.3%) in LURD (1 with functioning graft). Acute rejections occurred in 41% recipients in LRD and 35% in LURD (P = 0.37). Estimated GFR was lower in LURD than in LRD (49 ± 14 versus 59 ± 29 ml/min/1.73 m2; P = 0.032). One- and 3-year patient survival for LRD and LURD was 98.7% and 96.3% and 97.7% and 95%, respectively (P = 0.75). One- and 3-year graft survival was equivalent at 94.8% and 92.3% for LRD, and 98.4% and 93.7% for LURD, respectively (P = 0.18).

CONCLUSIONS

Outcome of LRD and LURD is comparable in terms of patient and graft survival, acute rejection rate and estimated GFR despite differences in demographics, HLA matching and re-transplants of recipients.
Specialist Outreach Service for On-Table Repair of Iatrogenic Bile Duct Injuries – A New Kind of ‘Travelling Surgeon’
Authors: Silva MA , Coldham C , Mayer AD , Bramhall SR , Buckels JAC , Mirza DF
Published: April 2008

INTRODUCTION

The objective of this study was to determine the outcome of on table repair of iatrogenic bile duct injuries (IBDIs) following laparoscopic cholecystectomy, by specialist hepatobiliary surgeons as an outreach service.

PATIENTS AND METHODS

Prospectively collected data on IBDI managed as an outreach service, was analysed retrospectively. The Strasberg classification was used to define types of injury.

RESULTS

There were 22 patients. Twenty (91%) had type E ‘classical’ excision injuries, two had types B and D. Two type E cases had co-existent vascular injury both with right hepatic artery injuries; one also had a co-existent portal vein injury. A Roux-en-Y hepaticojejunostomy was used to repair the IBDI in 21 (95%) patients. One type D injury had duct repair over a T-tube. No attempt was made to reconstruct the injured hepatic arteries, while the portal vein injury was primarily repaired. The median follow-up was 210 days (range, 47–1088 days). Two patients developed bile leak and cholangitis while another developed transient jaundice. There were no postoperative mortalities. All patients were followed up at our centre.

CONCLUSIONS

Repair of IBDI as an outreach service by specialist surgeons is feasible and safe, with minimal disruption to the patient pathway. Prompt recognition and definitive management may help reduce complaints and medicolegal litigation.
Detection of a Thalassemic α-Chain Variant (Hemoglobin Groene Hart) by Reversed-Phase Liquid Chromatography
Authors: Zanella-Cleon Isabelle , Becchi Michel , Lacan Philippe , Giordano Piero C , Wajcman Henri , Francina Alain
Published: April 2008

Background: Hemoglobin (Hb) Groene Hart [α119 (H2)Pro→Ser (α1)], also known as Hb Bernalda, is a nondeletional α-thalassemic Hb variant that is frequent in southern Italy and North Africa. This variant is not supposed to be produced in the erythrocytes of carriers. The α-thalassemic behavior of this variant has been explained as an impaired interaction between the α-globin chain and the α-Hb–stabilizing protein.

Methods: To separate globin chains, we developed a modified reversed-phase liquid chromatography (RPLC) procedure that uses acetonitrile–water solvents containing up to 3 mL/L trifluoroacetic acid. After RPLC, we characterized the isolated globin chains by electrospray ionization (ESI) mass spectrometry (MS) and analyzed their tryptic peptides with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nano-LC–ESI–MS/MS.

Results: RPLC detected an abnormal peak with a retention time substantially greater than that of the wild-type αA-globin chain. We identified this variant as Hb Groene Hart and found it in the hemolysates of 11 unrelated patients (1 homozygote, 9 heterozygotes, and 1 heterozygote associated with the −α3.7 deletion). These patients possessed abnormal hematologic features suggesting an α-thalassemia phenotype. Molecular modeling suggested that the increase in hydrophobicity was due to opening of the GH interhelical segment following replacement of amino acid residue 119 with a nonhelix breaker residue.

Conclusions: This method allows the detection of Hb variants at low concentrations, and adjusting the composition of the organic solvents enables the method to identify Hb variants with large changes in hydrophobicity.
Cell-Free Plasma DNA as a Predictor of Outcome in Severe Sepsis and Septic Shock
Authors: Saukkonen Katri , Lakkisto Päivi , Pettilä Ville , Varpula Marjut , Karlsson Sari , Ruokonen Esko , Pulkki Kari ,   for the Finnsepsis Study Group
Published: April 2008

Background: Increased concentrations of cell-free DNA have been found in plasma of septic and critically ill patients. We investigated the value of plasma DNA for the prediction of intensive care unit (ICU) and hospital mortality and its association with the degree of organ dysfunction and disease severity in patients with severe sepsis.

Methods: We studied 255 patients with severe sepsis or septic shock. We obtained blood samples on the day of study inclusion and 72 h later and measured cell-free plasma DNA by real-time quantitative PCR assay for the β-globin gene.

Results: Cell-free plasma DNA concentrations were higher at admission in ICU nonsurvivors than in survivors (median 15 904 vs 7522 genome equivalents [GE]/mL, P < 0.001) and 72 h later (median 15 176 GE/mL vs 6758 GE/mL, P = 0.004). Plasma DNA values were also higher in hospital nonsurvivors than in survivors (P = 0.008 to 0.009). By ROC analysis, plasma DNA concentrations had moderate discriminative power for ICU mortality (AUC 0.70–0.71). In multiple regression analysis, first-day plasma DNA was an independent predictor for ICU mortality (P = 0.005) but not for hospital mortality. Maximum lactate value and Sequential Organ Failure Assessment score correlated independently with the first-day plasma DNA in linear regression analysis.

Conclusions: Cell-free plasma DNA concentrations were significantly higher in ICU and hospital nonsurvivors than in survivors and showed a moderate discriminative power regarding ICU mortality. Plasma DNA concentration was an independent predictor for ICU mortality, but not for hospital mortality, a finding that decreases its clinical value in severe sepsis and septic shock.
An Examination of the Effects of Activating Persuasion Knowledge on Consumer Response to Brands Engaging in Covert Marketing
Authors: Wei Mei-Ling , Fischer Eileen , Main Kelley J.
Published: April 2008

Both marketers who use covert marketing tactics and those who seek to help consumers deal with them assume that people will be less amenable to covert marketing appeals if they are alerted to such appeals because their theories and beliefs about persuasion tactics—that is, their persuasion knowledge—will be activated. However, there has been little direct examination of the extent to which activating persuasion knowledge actually affects consumer responses to brands that engage in covert marketing. Building on prior research on covert marketing and marketplace persuasion knowledge, the authors investigate the effects of activating persuasion knowledge and explore potential moderating factors. The findings from three experimental studies indicate that activation can negatively affect consumer evaluations of embedded brands; however, negative effects are qualified by perceived appropriateness of covert marketing tactics and by brand familiarity. Further evidence indicates a condition under which activation can actually have a positive effect on consumer evaluations.
Commercializing Social Interaction: The Ethics of Stealth Marketing
Authors: Martin Kelly D. , Smith N. Craig
Published: April 2008

Firms striving to reach consumers through today's swell of marketing clutter frequently are employing novel marketing practices. Although many nontraditional marketing messages are effective through clever, entertaining, and, ultimately, benign means, others rely on deception to reach consumers. In particular, one form of covert marketing, known as stealth marketing, uses surreptitious practices that fail to disclose or reveal the true relationship with the company producing or sponsoring the marketing message. In addition to deception, stealth marketing can involve intrusion and exploitation of social relationships as means of achieving effectiveness. In this article, the authors consider the ethical implications using three stealth marketing case studies. They cast the discussion in the context of consumer defense mechanisms by employing literature on skepticism and persuasion knowledge to help explain the effectiveness of these practices. The authors identify the ethical problems inherent to stealth marketing and conclude their analysis with recommendations for marketers and public policy makers.
A Modified Triaxial Cell for Stress-Path Testing of Weak Rock (Hard Soils)
Authors: Stone K. J. L. , Katsaros K. I.
Published: April 2008

A simple conversion of a standard triaxial apparatus for stress path testing is presented and illustrated. The conversion is effected by incorporating a balanced ram arrangement into the top plate of a conventional triaxial cell, which, together with some additional modifications to the sample top cap and ram connection details, provides a cost-effective stress path testing cell. This modified triaxial cell, combined with a suitable external loading frame, allows the axial and radial stresses to be independently controlled. Consequently, any desired stress path can be applied to a specimen mounted in the modified cell. The functionality of the modified cell is demonstrated through the results of long-term stress-path tests performed as part of a creep study of intact medium porosity chalk. In this study, the modified cells were used with cantilever type loading frames, and subjected to continuous loading for periods in excess of 400 days. The performance of the modified cells was very satisfactory, and demonstrates that such an arrangement can provide a simple and a cost-effective system for conducting laboratory stress-path tests.
Issues in Modelling of Environment Assisted Cracking
Authors: Turnbull A
Published: April 2008

Risk-based inspection is becoming the cornerstone of modern practice in ensuring the integrity of engineering structures and components in a cost effective manner. The approach relies heavily on experience, insight and awareness of the likelihood of crack initiation and on models to predict the evolution of crack size. Environment assisted cracking poses a particular problem because of the sensitivity to transients and excursions in service behaviour and because models of crack growth kinetics, both empirical and deterministic, have significant limitations. A number of the existing issues in prediction are highlighted with recommendations for future development.
Strain Rate Dependent Environment Assisted Cracking of α/β-Ti Alloys in Chloride Solution
Authors: Richey E , Gangloff RP
Published: April 2008

Environment assisted cracking (EAC) occurs in annealed-α/β Ti-6A1-4V (ELI) and Ti-6Al-2Zr-2Sn-2Cr-2Mo in aqueous chloride solution, as evidenced by rising-displacement threshold stress intensity factors well below KIC and a mode transition from ductile fracture to transgranular cleavage of α. The acicular-α/α2 microstructure of Ti-6-2222 is susceptible to severe cracking in 3.5% NaCl compared to the equiaxed-α/α2 structure of Ti-6-4. Thresholds and growth rates depend on loading rate, and appear most environment sensitive at intermediate crack tip strain rates. EAC is sustained to high loading rates (dK/dt = 0.3 MPa√m/s for Ti-6-4 and above 10 MPa√m/s for Ti-6-2222) and crack growth rates are rapid (10 μm/s). The hydrogen environment embrittlement mechanism is consistent with such rapid cracking kinetics, but only if the process zone is within 0.001 to 1 μm of the crack tip surface. A near-tip process zone may be promoted by high H produced electrochemically on active areas of the crack surface, or by a sharp crack tip.
Hydrogen Embrittlement - Loading Rate Effects in Fracture Mechanics Testing
Authors: Koers RWJ , Krom AHM , Bakker A
Published: April 2008

The fitness for purpose methodology is more and more used in the oil and gas industry to evaluate the significance of pre-existing flaws and material deficiencies with regard to the suitability of continued operation of equipment. In this methodology, traditional fracture mechanics is integrated with expertise in inspection technology, material evaluation, and corrosion damage assessment, stress analysis and the mechanics of materials. Application of the fitness for purpose methodology for equipment operating in hydrogenation environments or in sour service is rather complex, in particular, due to the uncertainty in the reduction of the fracture toughness caused by hydrogen embrittlement. Hydrogen embrittlement is a time-dependent fracture process caused by the absorption and diffusion of atomic hydrogen into the steel, which results in a loss of ductility.

An experimental study has been performed to quantify the reduction of fracture toughness of an API 5L grade X56 pipeline steel, and a numerical model has been presented to understand the experimental results.
Role of Cyclic Pre-Loading in Hydrogen Assisted Cracking
Authors: Toribio J , Kharin V
Published: April 2008

A numerical analysis is performed of the effect of cyclic pre-loading regime on the posterior hydrogen assisted cracking behaviour of high-strength steel, considering mechanical items (stress-strain evolution) and chemical aspects (hydrogen diffusion). With regard to mechanical issues, a high resolution numerical modelling is carried out of the elastoplastic stress-strain field in the near-tip area under cyclic loading (to simulate fatigue pre-cracking) and posterior monotonie loading (to simulate a slow strain rate test), considering the role of large near-tip deformations. In the matter of chemical aspects, a quantitative modelling of hydrogen diffusion is performed near the crack tip, accounting for the transient stress-strain field that evolves from the compressive one after precracking to the tensile one during the test. Results show that hydrogen accumulation in fracture sites depends on residual stress distributions produced by cyclic pre-loading.
Environmentally Influenced Near-Threshold Fatigue Crack Growth in 7075-T651 Aluminum Alloy
Authors: Lee EU , Sanders HC , George K , Agarwala VV
Published: April 2008

The near-threshold fatigue crack growth behavior of the 7075-T651 aluminum alloy was studied in laboratory air, vacuum, and an aqueous 3.5% NaCl solution. Results indicate that a rising stress ratio (R) enhanced the near-threshold fatigue crack growth by increasing the crack growth rate (da/dN) and decreasing the threshold stress intensity range (ΔKth) in both laboratory air and aqueous 3.5% NaCl solution. However, the reverse was observed in vacuum. It was also noticed that the near-threshold fatigue crack growth resistance was greatest in vacuum, intermediate in aqueous 3.5% NaCl solution, and lowest in laboratory air. Conversely, the crack growth rate at given values of AK were shown to be greatest in laboratory air, less in 3.5% NaCl solution, and lowest in vacuum. In both laboratory air and aqueous 3.5% NaCl solution, ΔKth, initially decreased with increasing R until a critical stress ratio of Rc = 0.5 was reached, which it then leveled off or decreased slightly. The ΔKth values for these two environments appear to converge at a higher R. On the other hand, in vacuum, the ΔKth, increased linearly with increasing R. In addition, at lower R, a greater resistance to near-threshold fatigue crack growth was detected in aqueous 3.5% NaCl solution than in laboratory air. This is presumably attributed to crack closure that has been induced by accumulation of corrosion product in the crack-tip.
Passive Sampling Devices (PSDs) as Biological Surrogates for Estimating the Bioavailability of Organic Chemicals in Soil
Authors: Wells JB , Lanno RP
Published: April 2008

Organic chemical exposure in soil toxicity tests and in ecological risk assessment of terrestrial systems is usually expressed as the total chemical measured. Possible alternatives to total chemical measures of organic chemical bioavailability and exposure include body residues in test organisms, soil extraction with selective solvents, and passive sampling devices (PSDs) as biological surrogates. Semipermeable membrane devices (SPMDs) offer potential as a biological surrogate in soil systems. Solid-phase microextraction (SPME) fibers are a rapid and sensitive means for detecting PAHs in soil and have the advantage of not requiring solvent extraction of soil. The objective of this study was to compare chemical uptake and residues in earthworms, SPMDs, and SPMEs exposed in artificial soil spiked with phenanthrene (PHE). Bioavailable PHE, as assessed by mortality and PHE body residues, varied dramatically with soil organic matter content. Both SPMEs and SPMDs could discriminate differences in PHE availability between treatments. However, PHE levels measured using SPMEs were more precise and allowed discrimination between toxic and non-toxic levels of PHE, while PHE levels in SPMDs were too variable for use as a predictive tool.
Assay Variance in a Granular Formulation Can Predict Mixture Homogeneity
Authors: Goss GR , Hendrix C , Baldwin HM
Published: April 2008

In granular formulations, the formulator often wishes to spray a small amount of an active ingredient onto a granule. An accurate amount and uniform distribution are the key to product performance in the field. Once product is formulated, the QC lab can provide information on average active ingredient amount. Seldom is there reliable information on active ingredient distribution. Active ingredient distribution can be estimated by observing assay variance. The greater the mixture homogeneity, the less the assay variation and vice versa. Also, the greater the homogeneity of a mixture, the less assay variance is affected by sample size. That is, variation varies inversely with sample size and therefore the number of particles sampled. Or, σ2 = k/N where σ2 is the variance, k is a constant and N is the number of particles sampled. The value of k will vary inversely with mixture homogeneity. In other words, the value of k will approach zero with a completely homogeneous material or a large enough sample. One can determine mixture homogeneity by determining the variance. Using a single sample size and utilizing the binomial theorem σ2 = (A2/pN)(l-p) where A = assay percent active, p = fraction of particles with chemical, and N = number of particles sampled, k from the previous equation is then (A2/p)(l-p). This paper discusses the theory and practicality of this equation.
The Development of a Spread Test Method for Agricultural Spray Adjuvants
Authors: Volgas G
Published: April 2008

The ASTM E-35 subcommittee on spray adjuvants has been working for several years on adjuvant test methodology. This subcommittee has already obtained approval on several test methods and has been working on the development of a spreading test for the last 3 years. This method is not intended to replace sophisticated image analysis techniques currently being used in some laboratories. It is intended to provide a simple, inexpensive evaluation of the spread characteristics of spray droplets.

The method employs a circular grid overlaying a thin sheet of Parafilm® M and visual observations by the user to determine spread radii. The spread radii of a standardized droplet can be determined reasonably to within 0.5 mm. This test has now been validated by an inter-laboratory study conducted by members of ASTM E-35. This paper will present the data and thereby provide a permanent record. The paper will also attempt to provide an accounting for the standard conditions set in this test method.
Classification of Adjuvants and Adjuvant Blends by Effects on Cuticular Penetration
Authors: Cronfeld P , Lader K , Baur P
Published: April 2008

The potential of selected surfactants and other adjuvants to increase cuticular penetration of foliar applied active ingredients was investigated under defined environmental conditions (RH, T). The herbicide cyanazine and the weak acid NAA were selected as model compounds. The time course of cyanazine penetration through apple leaf cuticles in the presence of different adjuvants varied from no penetration within 5 days to almost quantitative penetration within 5 hours. Effective adjuvants are distinguished as donor adjuvants, that produce a liquid film on the surface, and accelerator adjuvants, that additionally can penetrate into and increase solute mobility in the cuticle. Adjuvant efficacy in both groups differs significantly among products and is characterized according to chemistry and concentration, technical product quality, environmental factors, and plant organ (leaf/fruit) and species, respectively. An example is given to combine adjuvants to manipulate the time course of penetration of NAA. The limited use of HLB as a general indicator for the efficacy of adjuvants at the cuticular level is discussed.