bluuebunny/crossref_metadata_2025 huggingface dataset:
Start-up absorptive capacity: Does the owner’s human and social capital matter?
Authors: Debrulle Jonas , Maes Johan , Sels Luc
Published: November 2013

This study investigates how a business owner’s human and social capital affects start-up absorptive capacity under different environmental conditions. From an analysis of a sample of 199 Flemish start-ups, the study observes that the owners’ start-up experience and bridging social capital are positively and significantly related to the new venture’s ability to acquire, assimilate and exploit external information. In addition, the findings reveal a positive but decreasing effect of owner-specific human capital as a function of environmental turbulence. Furthermore, the study finds that management experience significantly stimulates start-up absorptive capacity within highly dynamic environments, whereas it hinders it within stable environments. Finally, implications of the study and opportunities for future research are provided.
Endovenous laser ablation of varicose veins with the 1470 nm diode laser using a radial fiber – 1-year follow-up
Authors: von Hodenberg E , Zerweck C , Knittel M , Zeller T , Schwarz T
Published: November 2013

Background:

Endovenous laser ablation is one of the most accepted treatment options for insufficient great and small saphenous veins. The aim of this study was to investigate the long-term efficacy and safety of the radial fiber (ELVeS-radial kit™) for the 1470 nm diode laser in a 1-year follow-up.

Methods:

A total of 308 lower limbs with primary insufficiency of great and small saphenous veins or insufficient tributaries were included in the prospective observational cohort study. The primary efficacy endpoint of the study was ultrasonographic proven elimination of venous reflux after at least 1 year. Secondary efficacy and further safety end points after 1 year were as follows: (1) sonographic exclusion of recanalization of the treated vein segments, (2) deep vein thrombosis, clinical pulmonary embolism or superficial vein thrombosis as defined by objective testing, (3) death from any cause, (4) persistent clinical complaints such as pain and paresthesia, (5) recurrent varicose veins. Patient satisfaction was assessed using a CIVIQ-2 questionnaire after 1 year.

Results:

Follow-up could be completed in 91.2% of the patients. Excellent efficacy numbers with 99.6% occlusion of the treated varicose veins as elimination of reflux could be demonstrated. After 1 year, 96% of the treated veins disappeared completely sonographically; one recanalization was observed. No deep vein thrombosis or pulmonary embolism occurred, three superficial vein thrombosis were diagnosed in follow-up examinations. Four patients died, not related to pulmonary embolism. No persistent pain or paresthesia occurred in the follow-up. Recurrent varicose veins were diagnosed in 10 patients (2.81%).

Conclusion:

One-year follow-up showed that endovenous laser treatment of varicose veins with 1470 nm diode laser using the radial fiber is highly effective, also regarding in a 1-year follow-up.
Home-based palliative care: A systematic literature review of the self-reported unmet needs of patients and carers
Authors: Ventura Adriana D , Burney Susan , Brooker Joanne , Fletcher Jane , Ricciardelli Lina
Published: November 2013

Background:

There have been many studies on the unmet needs of palliative care patients and carers from the perspective of bereaved caregivers. However, the unmet needs of palliative care patients and carers from the perspective of current patients and their carers have received little research attention.

Aim:

As home-based services have become one of the main delivery models of palliative care, the aim of this review was to describe, evaluate and summarise the literature on the unmet needs of palliative home care patients and carers.

Design:

The systematic review of qualitative and quantitative studies was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Data sources:

PubMed, CINAHL, Embase, MEDLINE, PsycINFO, AMED and CareSearch were searched to find empirical studies on the self-reported unmet needs of palliative home care patients and carers.

Results:

Nine qualitative studies, three quantitative studies and three mixed-design studies were identified. The most frequently reported unmet need was effective communication with health-care professionals, the lack of which negatively impacted on the care received by patients and carers. Physical care needs were met, which indicates that the examined palliative home care services were delivering satisfactory care in this domain, but lacking in other areas.

Conclusions:

The focus therefore should be on improving other aspects of patient care, including communication by health professionals to prevent or reduce suffering in areas such as psychosocial domains. Valid and reliable quantitative measures of unmet needs in palliative care are needed to examine this area more rigorously.
End-of-life care and achieving preferences for place of death in England: Results of a population-based survey using the VOICES-SF questionnaire
Authors: Hunt Katherine J , Shlomo Natalie , Addington-Hall Julia
Published: November 2013

Background/aim:

Health policy places emphasis on enabling patients to die in their place of choice, and increasing the proportion of home deaths. In this article, we seek to explore reported preferences for place of death and experiences of care in a population-based sample of deaths from all causes.

Design:

Self-completion post-bereavement survey.

Setting/Participants:

Census of deaths registered in two health districts between October 2009 and April 2010. Views of Informal Carers – Evaluation of Services Short Form was sent to each informant (n = 1422; usually bereaved relative) 6–12 months post-bereavement.

Results:

Response was 33%. In all, 35.7% of respondents reported that the deceased said where they wanted to die, and 49.3% of these were reported to achieve this. Whilist 73.9% of those who were reported to have a preference cited home as the preferred place, only 13.3% of the sample died at home. Cancer patients were more likely to be reported to achieve preferences than patients with other conditions (p < .01). Being reported to have a record of preferences for place of death increased the likelihood of dying at home (odds ratio = 22.10). When rating care in the last 2 days, respondents were more likely to rate ‘excellent’ or ‘good’ for nursing care (p < .01), relief of pain (p < .01) and other symptoms (p < .01), emotional support (p < .01) and privacy of patient’s environment (p < .01) if their relative died in their preferred place.

Conclusions:

More work is needed to encourage people to talk about their preferences at the end of life: this should not be restricted to those known to be dying. Increasing knowledge and achievement of preferences for place of death may also improve end-of-life care.
Rabbit hepatic arterial anatomy variations: implications on experimental design
Authors: Tam Alda L , Melancon Marites P , Ensor Joe , Liu Yang , Dixon Katherine , McWatters Amanda , Gupta Sanjay
Published: November 2013

Background

The VX2 rabbit model of liver cancer is commonly used to evaluate the efficacy of locoregional anticancer therapy and knowledge of the hepatic arterial anatomy in the rabbit is important for catheter-directed experiments.

Purpose

To describe the normal anatomy and anatomic variations of the celiac axis and hepatic artery in the rabbit.

Material and Methods

Angiograms of 222 rabbits were retrospectively reviewed. The branching pattern of the celiac axis was classified and the diameters of the major branches were measured. Paired t-tests were used to compare the difference between the average sizes of arteries.

Results

Variant celiac axis or hepatic artery anatomy was noted in 25.9% of angiograms, with the gastric branches arising from the proper hepatic artery in 23.3% of cases. The celiac axis could be successfully classified into one of five distinct branching patterns in 193 (86.9%) cases. The mean diameters of the right and left hepatic arteries were 0.67 mm (95% CI [0.64, 0.7]) and 1.25 mm (95% CI [1.19, 1.31]), respectively. The mean diameters of the medial and lateral branches of the left hepatic artery were 0.63 mm (95% CI [0.6, 0.67]) and 0.91 mm (95% CI [0.86, 0.96]), respectively. The right hepatic artery was significantly smaller than the left hepatic artery and the lateral branch of the left hepatic artery (all P values <0.0001).

Conclusion

Arterial variants in the rabbit are not uncommon. The proper hepatic artery often gives origin to gastric artery branches. To facilitate superselective intra-arterial intervention, the left lateral lobe of the liver should be targeted for tumor implantation because of the significant size difference between the right and left hepatic arteries.
Risk factors of radiation dose in patients undergoing peripherally-inserted central catheter procedure using conventional angiography equipment and flat panel detector-based mobile C-arm fluoroscopy
Authors: Lee TaeBum , Shin Sung Wook , Choi Dongil , Cho Sung Ki , Hyun Dongho , Do Young Soo , Jeon SungChae , Cha BoKyung , Bok Eun Kyung , Kim Seonwoo
Published: November 2013

Background

Although peripherally-inserted central catheter (PICC) insertion is commonly performed under fluoroscopic guidance, few reports have addressed performance and dosimetry when PICC is inserted under C-arm fluoroscopy.

Purpose

To evaluate the risk factors of radiation dose in performing PICC insertion using flat panel detector-based mobile C-arm fluoroscopy and a conventional angiography machine.

Material and Methods

Ninety-eight patients underwent the PICC procedure using conventional angiography equipment ( n=49) or flat panel detector-based mobile C-arm fluoroscopy ( n=49). Data were prospectively analyzed from July to November 2012. Dose-area product (DAP), tube voltage, tube current, fluoroscopy time, and image quality measured on a 5-point scale were estimated and compared using appropriate statistical tests.

Results

There were no significant differences in tube voltage, fluoroscopy time, and image quality between conventional angiography and mobile C-arm fluoroscopy. DAP, mean arm tube current, and tube current in chest fluoroscopy were significantly lower in mobile C-arm fluoroscopy than using the conventional angiography machine ( P <0.05). Multivariate analysis identified tube current in chest fluoroscopy, arm tube current, and fluoroscopy equipment as significant risk factors for elevated radiation dose in PICC insertion.

Conclusion

PICC insertion can be performed using flat panel detector-based mobile C-arm fluoroscopy instead of a conventional angiography machine. Image quality and fluoroscopy time were not different between the two systems and the use of C-arm fluoroscopy significantly reduced radiation dose.
A Multi-Site Controlled Trial of the R&R2MHP Cognitive Skills Program for Mentally Disordered Female Offenders
Authors: Jotangia Amit , Rees-Jones Angharad , Gudjonsson Gisli H. , Young Susan
Published: November 2013

This study aimed to evaluate the acceptability and efficacy of delivering the Reasoning and Rehabilitation Mental Health Program (R&R2MHP) to female mentally disordered offenders detained in medium and low secure hospital settings. Group treatment participants ( N = 18) and control participants receiving treatment as usual ( N = 20) completed self-report measures pre- and post-group. An informant measure of ward behavior was also completed by staff. Violent attitudes and locus of control were assessed at 3-month follow-up. Program completion was excellent (89%). A conservative intention-to-treat analysis found significant treatment effects post-group for positive problem-solving orientation, rational problem-solving style, and locus of control (medium-large effect), but no treatment effect for violent attitudes, anger, and ward behavior. At follow-up, a large treatment effect was found for locus of control. Ad hoc per protocol analyses found a large treatment effect for ward behavior. The findings provide preliminary support for the feasibility and utility of delivering R&R2MHP to females in secure psychiatric settings.
Fracture mechanics approach to fretting fatigue behaviour of coated aluminium alloy components
Authors: Navarro Carlos , Muñoz Sergio , Domínguez Jaime
Published: November 2013

This article analyses the effect that different coatings have on the fretting fatigue behaviour of aluminium alloy mechanical components. To this end, a set of fretting fatigue tests of coated and uncoated specimens was carried out. The contact pads in the tests had a spherical surface, and a condition of partial slip was always maintained. The materials employed were aluminium alloy 7075-T651; coatings of molybdenum bisulphide, modified with tungsten carbide, MoS2–WC; and a commercial treatment known as Nituff®, which is a hard, anodized coating containing particles of polytetrafluoroethylene. The experimental results are discussed, and an analytical model based on fracture mechanics was applied to estimate the experimental fatigue lives obtained in the tests.
Sphenopalatine ganglion neuromodulation in migraine: What is the rationale?
Authors: Khan Sabrina , Schoenen Jean , Ashina Messoud
Published: November 2013

Objective

The objective of this article is to review the prospect of treating migraine with sphenopalatine ganglion (SPG) neurostimulation.

Background

Fuelled by preliminary studies showing a beneficial effect in cluster headache patients, the potential of treating migraine with neurostimulation has gained increasing interest within recent years, as current treatment strategies often fail to provide adequate relief from this debilitating headache. Common migraine symptoms include lacrimation, nasal congestion, and conjunctival injection, all parasympathetic manifestations. In addition, studies have suggested that parasympathetic activity may also contribute to the pain of migraineurs. The SPG is the largest extracranial parasympathetic ganglion of the head, innervating the meninges, lacrimal gland, nasal mucosa, and conjunctiva, all structures involved in migraine with cephalic autonomic symptoms.

Conclusion

We propose two possible mechanisms of action: 1) interrupting the post-ganglionic parasympathetic outflow to inhibit the pain and cephalic autonomic symptoms, and 2) modulating the sensory processing in the trigeminal nucleus caudalis. To further explore SPG stimulation in migraineurs as regards therapeutic potential and mode of action, randomized clinical trials are warranted.
Definitions of medication-overuse headache in population-based studies and their implications on prevalence estimates: A systematic review
Authors: Westergaard Maria L , Hansen Ebba Holme , Glümer Charlotte , Olesen Jes , Jensen Rigmor H
Published: November 2013

Background

Case definitions of medication-overuse headache (MOH) in population-based research have changed over time. This study aims to review MOH prevalence reports with respect to these changes, and to propose a practical case definition for future studies based on the ICHD-3 beta.

Methods

A systematic literature search was conducted to identify MOH prevalence studies. Findings were summarized according to diagnostic criteria.

Results

Twenty-seven studies were included. The commonly used case definition for MOH was headache ≥15 days/month with concurrent medication overuse ≥3 months. There were varying definitions for what was considered as overuse. Studies that all used ICHD-2 criteria showed a wide range of prevalence among adults: 0.5%–7.2%.

Conclusions

There are limits to comparing prevalence of MOH across studies and over time. The wide range of reported prevalence might not only be due to changing criteria, but also the diversity of countries now publishing data. The criterion “headache occurring on ≥15 days per month” with concurrent medication overuse can be applied in population-based studies. However, the new requirement that a respondent must have “a preexisting headache disorder” has not been previously validated. Exclusion of other headache diagnoses by expert evaluation and ancillary examinations is not feasible in large population-based studies.
Changing Prevalence of Diabetes for Texas Nursing Home Residents, 1999-2009
Authors: Coxe Leland M. , Lennertz Kathie , McCullough Sherry
Published: November 2013

This article examines change in the composition of the Texas nursing home population between 1990 and 2009 in relation to the changing prevalence of diabetes. Data from the federal Minimum Data Set for Texas for 1999 and 2009 were analyzed for change in proportion of age groups by the Two-Sample Proportion Test. Change by gender within age groups while controlling for race/ethnicity was analyzed by the Cochran–Mantel–Haenszel test. The percentage of nursing home residents aged 50 to 64 years increased from 8% in 1999 to 12% in 2009, and the change was statistically significant for each race/ethnic group and both genders. The percentage reporting diabetes increased among all groups with more pronounced change for minorities. These results point to a need for closer examination of the impacts of changing diabetes prevalence on nursing homes.
Life cycle assessment of manure management and nutrient recycling from a Chinese pig farm
Authors: Luo Yiming , Stichnothe Heinz , Schuchardt Frank , Li Guoxue , Huaitalla Roxana Mendoza , Xu Wen
Published: November 2013

Driven by the growing numbers of intensified pig farms around cities in China, there are problems of nutrient surplus and shortage of arable land for utilising the manure. Hence, sustainable livestock systems with effective manure management are needed. The objective of this study is to compare the existing manure treatment of a typical pig farm in Beijing area (separate collection of faeces; ‘Gan qing fen’ system) with an alternative system and to identify the nutrients flow of the whole farm in order to quantify environmental burdens and to estimate the arable land required for sustainable nutrients recycling. Life cycle assessment is used for this purpose. Acidification potential (AP), eutrophication potential (EP) and global warming potential (GWP) are analysed in detail; the functional unit is the annual production of the pig farm. The results show that the cropland area demand for sustainable land application of the effluent can be reduced from 238 to 139 ha with the alternative system. It is possible to transfer 29% of total nitrogen, 87% of phosphorus, 34% of potassium and 75% of magnesium to the compost, and to reduce the total AP, EP and GWP of manure management on the farm by 64.1%, 96.7% and 22%, respectively, compared with the current system. Besides an effective manure management system, a full inventory of the regional nutrients flow is needed for sustainable development of livestock systems around big cities in China.
Under-utilisation of organic wastes during brownfield regeneration to community woodland: Tackling the barriers
Authors: Ashwood Francis E , Doick Kieron J , Atkinson Gail E , Chenoweth Jonathan
Published: November 2013

The regeneration of brownfield land to greenspace is a governmental policy objective of many European countries. Healthy vegetation establishment and growth is an essential component of successful greenspace establishment, and research has shown that a planting medium of an appropriate standard for supporting vegetation can be created through amendment of soil-forming materials with organic wastes. However, failed regeneration projects suggest that barriers may exist that prevent the use of suitable quality soil materials. The aim of this research was to identify barriers to the use of organic wastes for improving soil materials for brownfield regeneration to community woodland. We conducted interviews with a range of professionals experienced in regeneration to greenspace, and used content analysis on interview transcripts. A diverse set of barriers was revealed, including a low technical awareness among some professional groups of how to improve soil quality, coupled with a low awareness of the published technical guidance. Other barriers include regulatory and project management issues, which influence the timings and economics of raising brownfield soil quality. We highlight areas in which future efforts may be focused to improve the quality of planting media used in land regeneration. Such effort will improve the sustainability of greenspaces created and complement effective management of organic waste streams.
Removal of nitrogen from MBT residues by leachate recirculation in combination with intermittent aeration
Authors: Tran Hoai Nam , Münnich Kai , Fricke Klaus , Harborth Peter
Published: November 2013

Mechanical–biological treatment (MBT) techniques have been used to reduce the emission potential of waste before placement in landfills for a couple of years, especially in Europe. The main focus of MBT is on the reduction of native organic substances and not on nitrogen compounds. As a result, the concentrations of organic substances in leachate from MBT landfills are considerably reduced in comparison to leachates from municipal solid waste landfills, while the ammonia nitrogen concentrations remain at a high level. From the stabilization of old landfills it is well known that recirculation of leachate and supplementary aeration can reduce emissions to an acceptable level in a comparatively short time. In a series of laboratory-scale tests the efficiency of this technique for MBT residues was investigated under different boundary conditions. While the effect of leachate recirculation is also well known for MBT residues, the additional aeration has so far not been investigated. The results show that this technique has only a limited influence on the reduction of organic carbon compounds. In view of nitrogen compounds, only the additional aeration during recirculation shows a strong effect on the quality of leachate, in which the concentrations of ammonium and total nitrogen are reduced by more than 90%. The results indicate that by using simple techniques the long-term emission behavior of MBT residues can be quickly reduced to an acceptable level.
Concurrent Validity of the WISC-IV and DAS-II in Children With Autism Spectrum Disorder
Authors: Kuriakose Sarah
Published: November 2013

Cognitive assessments are used for a variety of research and clinical purposes in children with autism spectrum disorder (ASD). This study establishes concurrent validity of the Wechsler Intelligence Scales for Children–fourth edition (WISC-IV) and Differential Ability Scales–second edition (DAS-II) in a sample of children with ASD with a broad range of cognitive abilities. Participants achieved significantly higher overall scores on the DAS-II and nearly half the sample achieved a higher classification label on the DAS-II. The difference between overall scores is suggested to be attributable to a relative weakness in processing speed, which is assessed on the WISC-IV but not the DAS-II. Autistic symptomatology was not associated with cognitive scores, while adaptive behavior was positively associated. Neither was associated with the magnitude of difference between overall scores. Choice of assessment should be considered carefully given the systematic differences in overall scores produced in this population.
How Emotional Intelligence Mediates Emotional Labor in Public Service Jobs
Authors: Guy Mary E. , Lee Hyun Jung
Published: November 2013

Most public service jobs involve emotionally intense work demands. For this reason, the terms emotional intelligence and emotional labor have entered the lexicon of public service. The former refers to the ability to sense and regulate one’s own emotions as well as to sense others’ emotional state, while the latter refers to the exercise of emotive skills to get the job done. This study examines how emotional intelligence mediates emotional labor in the performance of work duties by using job satisfaction and burnout as criterion variables. Although findings are mixed with regard to job satisfaction, a statistically significant relationship exists in the mediation between emotional labor and burnout. Specifically, the ability to regulate one’s own emotions decreases burnout. Implications for training and development are discussed.
Epileptic Encephalopathy With Continuous Spike and Wave During Sleep Associated to Periventricular Leukomalacia
Authors: De Grandis Elisa , Mancardi Maria Margherita , Carelli Valentina , Carpaneto Manuela , Morana Giovanni , Prato Giulia , Mirabelli-Badenier Marisol , Pinto Francesca , Veneselli Edvige , Baglietto Maria Giuseppina
Published: November 2013

Periventricular leukomalacia is the most common type of brain injury in premature infants. Our aim is to describe the frequency and the features of epilepsy in a single-center population of 137 children with periventricular leukomalacia. Forty-two of the 137 (31%) patients presented epilepsy. Twelve percent of these patients presented West syndrome, whereas 19% showed a pattern of continuous spike-waves during slow sleep syndrome. In the latter group, outcome was frequently unfavorable, with a greater number of seizures and more drug resistance. A significant association was found between epilepsy and neonatal seizures, spastic tetraplegia, and mental retardation. Although less common than in other forms of brain injury, epilepsy is nevertheless a significant complication in children with periventricular leukomalacia. The fairly frequent association with continuous spike-waves during slow sleep syndrome deserves particular attention: electroencephalographic sleep monitoring is important in order to provide early treatment and prevent further neurologic deterioration.
Neuropsychological Findings in Childhood Narcolepsy
Authors: Posar Annio , Pizza Fabio , Parmeggiani Antonia , Plazzi Giuseppe
Published: November 2013

Narcolepsy with cataplexy is a severely disabling disorder very often arising in childhood. Data on neuropsychological impairment in children are scant. We administered standardized neuropsychological tests to 13 children with narcolepsy with cataplexy. Overall, our patients displayed multiple patterns of cognitive and behavioral dysfunction, and often academic failure (7 cases out of 13). All children had a normal full intelligence quotient (IQ), but 3 patients presented a significantly higher and 2 a significantly lower Verbal IQ compared to Performance IQ, respectively. Mean sleep latency was significantly correlated ( P < .05) to alertness functions. Eight patients displayed behavioral problems: emotional symptoms and conduct problems prevailed. Childhood narcolepsy with cataplexy represents a risk factor for subtle and heterogeneous cognitive impairments potentially resulting in academic failure, despite the normal IQ. These children also have a certain psychopathological risk. All this seems to be at least partially detached from the direct effects of daytime sleepiness.
Wernicke Encephalopathy in Pediatric Neuro-oncology
Authors: Cefalo Maria Giuseppina , De Ioris Maria Antonietta , Cacchione Antonella , Longo Daniela , Staccioli Susanna , Arcioni Francesco , Bernardi Bruno , Mastronuzzi Angela
Published: November 2013

Wernicke encephalopathy represents a well-known entity characterized by a set of cognitive and neurologic alterations. Wernicke encephalopathy is rare and under-recognized in childhood and may be fatal. Few cases have been documented in pediatric oncology. We report on 2 Wernicke encephalopathy cases that occurred in children having a brain tumor. The diagnosis of Wernicke encephalopathy was suggested by clinical manifestations associated with the typical radiologic findings and a laboratory evidence of thiamine deficiency. No large series have been published to support the evidence that pediatric malignancies represent a demonstrated factor of increased risk to develop a Wernicke encephalopathy. Moreover, the diagnosis may be even more difficult in brain tumors, considering the overlapping symptoms and the risk of encephalopathy related to both the disease and the treatment. Wernicke encephalopathy should be considered in all children with cancer presenting a neurologic deterioration, mainly in brain tumors. An early diagnosis is imperative for a prompt therapy that might prevent or minimize the irreversible brain damage related to this condition.
Adam Walsh Act Compliance in Pennsylvania
Authors: Spraitz Jason D. , Frenzel Erika Davis , Bowen Kendra N. , Bowers James H. , Phaneuf Shannon
Published: November 2013

In December 2012, Pennsylvania became the 16th state to comply with regulations stipulated in the Adam Walsh Act (AWA). Title I of AWA stipulates that all jurisdictions support a sex offender registry comprised of three registration levels: 15 years, 25 years, and life. Prior to implementation of AWA guidelines, the sex offender registry in Pennsylvania consisted of two registration levels: 10 years and life. Given the collateral consequences that sex offender registries create, we were interested in how registered offenders in Pennsylvania felt about the new legislation. As part of a larger project, self-report surveys were mailed to registrants in one urban county in Pennsylvania. Participants were asked about their knowledge of impending AWA-compliance and how they would be affected by it. Results suggest that sex offenders in Pennsylvania are more likely than their peers in other states to be fearful of the consequences of this change.
Fuzzy rule-based modeling of machining parameters for surface roughness in turning carbon particle-reinforced polyamide
Authors: Palanikumar K , Rajasekaran T , Latha B
Published: November 2013

Carbon particle-reinforced polyamides (PAs) are finding increasing applications in many engineering fields. Machining of these materials is needed for obtaining near net shape and precision fit. In this work, application of fuzzy logic technique along with the Taguchi’s orthogonal array is used in turning of PA6 to develop a model for predicting surface roughness. There are many factors affecting the surface roughness. Among these factors the machining parameters that play a dominant role are cutting speed, feed, and depth of cut. The adequacy of the fuzzy rule-based model is verified through coefficient of determination. The correlation that exists between the experimental value and the fuzzy model is on the higher side; hence, the fuzzy logic technique can be effective when estimating the surface roughness in turning of PA6.
Thermal modelling of the laser-assisted thermoplastic tape placement process
Authors: Stokes-Griffin Christopher Mark , Compston Paul , Matuszyk Timothy I , Cardew-Hall Michael J
Published: November 2013

Thermoplastic tape placement opens the possibility of a fully automated composite production. The resulting quality is highly dependent on the thermal history during consolidation. This article focuses on the thermal modelling of a tape placement system employing a near-infrared laser. A nonlinear two-dimensional finite element model is presented for a carbon fibre reinforced thermoplastic (AS4/PEEK) composite placement process using a conformable roller. The relative influence of roller geometry, roller temperature and thermal contact resistance was studied. Temperature measurements were performed using thermocouples welded to the substrate. The model predictions show good correlation in terms of timing of the irradiation, shadow and consolidation regions. The roller temperature was found to have the most significant impact on the bond line temperature distribution.
Characterization and simulation of tensile behavior of graphene/polypropylene nanocomposites using a novel strain-rate-dependent micromechanics model
Authors: Shokrieh Mahmood M , Joneidi Vahab Ahmadi , Mosalmani Reza
Published: November 2013

In this article, a newly developed model is utilized to simulate the strain-rate-dependent constitutive equation of graphene/polypropylene nanocomposites, using the mechanical properties of the constituent materials of nanocomposites. The model is a combination of the micromechanics and Goldberg models called strain-rate-dependent micromechanics (SRDM) model. The Johnson-Cook material model is used by the explicit finite element code LS-DYNA to simulate the strain-rate-dependent mechanical behavior of the standard tensile test specimen made of graphene/polypropylene nanocomposites under dynamic loading and its constants are calculated by the SRDM model. Polypropylene reinforced with 0.5, 1.0, and 2.0 wt% graphene sheets were prepared via coating polypropylene with graphene particles. Then, by melt blending in a twin-screw extruder followed by an injection molding process, the nanocomposite samples are manufactured. Good enhancements of Young’s modulus and yield stress at very low graphene contents are achieved. To evaluate the current model, the results are compared with the experimental result of the standard tensile test specimen. A good agreement between the experimental data and the SRDM model is achieved.
Influence of polyhedral oligomeric silsesquioxanes on thermal and mechanical properties of melt-mixed poly(methyl methacrylate)/polyhedral oligomeric silsesquioxanes composites
Authors: Illescas Silvia , Arostegui Asier
Published: November 2013

In this study, the influence of the functionalization of fully or incomplete condensed polyhedral oligomeric silsesquioxanes composites (POSS) nanoparticles on the properties of poly(methyl methacrylate) (PMMA)-based composites has been studied. POSS with different organic substituents (methacryl, methacrylateisooctyl and trisilanolphenyl) are taken into account and added to the PMMA matrix by direct melt blending at loadings between 0 and 5 wt%. Significant differences in compatibility were observed depending on the structure of nanoparticles. POSS aggregation occurred during blending producing micron-sized aggregates in the composites. The thermal decomposition temperature of the composites with good dispersion of POSS aggregates increased under oxidative conditions. There were no significant changes in other thermal and mechanical properties of the composites. The relationships among these effects and the morphological characteristics of the systems were analysed.
Error analysis and prototype testing of deepwater pipe flange connection tool
Authors: Wang Liquan , Wang Caidong , Liu Jun
Published: November 2013

The key factor for underwater petroleum pipeline flange connection tool is its 20 bolts synchronous lead-in nuts. The alignment accuracy of bolts and nuts is critical for bolts lead-in nuts. In order to analyze the accuracy and design issues of the pipeline flange connection tool, the robot kinematics modeling method is adopted. Using the multi-body kinematics theory to homogeneous transformation matrix, the error model of deepwater pipe flange connection tool is established through total differential of the machinery pose transformation matrix. The error model of the tool is established by computer simulation, and the effect of the structure parameters on the bolt end pose error is analyzed. Based on the method of error matching design, the error in the deepwater pipe flange automatic connection tool is determined. Considering the specific structure of the connection tool, the adjusting mechanism for bolt angle error is also designed. Therefore, the hardware compensation of bolt angle error is achieved successfully, and it improves the positioning accuracy of the bolt end. Tests on bolt lead-in prototype are conducted. The experimental results show that the bolt could successfully lead into the nut and confirm the accuracies of the error model and design of the pipeline flange connection tool.
Experimental method study on heat flux measurement on sharp leading edge
Authors: Zhou Weixing , Wang Dan , Bao Wen , Qin Jiang
Published: November 2013

The heat-flux measurement is the precondition of the structure and cooling system design for hypersonic aircraft, while no experiment method can be applied to the heat-flux measurement of the sharp leading edge for its small size and high-heat flux. In this article, an experimental method based on the law of inverse conduction is proposed in this paper for the calculation of heat flux from the inner wall temperature of the sharp leading edge. This experimental method proposed includes the method of inner wall transient temperature acquisition, smoothing technique, and the Matlab and Fluent cosimulation postprocessor, where Fluent is used as a 3D unsteady heat conduction solver, and conjugate gradient method is applied for optimization. The effectiveness of the proposed method is verified by its application in the scramjet experiment for the heat-flux measurement on the strut-leading edge, which greatly helps the assessment of thermal environment with a total error of less than 5%.
Exploration of supersonic confined mixing layer: Effect of dissimilar gases at different temperatures
Authors: Javed Afroz , Paul PJ , Rajan NKS , Chakraborty Debasis
Published: November 2013

The growth rate of high-speed mixing layer between two dissimilar gases is explored through the model free simulation results. To analyse the cause for the higher mixing layer growth rate in comparison to the existing values reported in literature, the results were compared with the model free simulations of mixing of two high-speed streams of nitrogen (similar gas) at matched temperature and density. The analysis indicates that pressure and density fluctuations no longer remain correlated completely for the mixing layer formed between two dissimilar gases at different temperatures in contrast to the complete pressure density correlation for similar gases. It has been observed that the correlation between temperature and density fluctuations is near −1.0 for dissimilar gases in the mixing layer region and is much higher than for similar gases. It is concluded that mixing layer of similar gases shows a decrease in growth rate due to compressibility effect, while that of dissimilar gases shows a decrease due to dominant temperature effect on density.
Attitude control of Earth-pointing spacecraft using nonlinear H∞ control
Authors: Binette Mark R , Damaren Christopher J , Pavel Lacramioara
Published: November 2013

The attitude control of an Earth-pointing spacecraft in a circular orbit, subject to the gravity-gradient torque, is explored. The spacecraft attitude is described using the modified Rodrigues parameters. A series of controllers are designed using the nonlinear [Formula: see text] control methodology and are subsequently generated using a Taylor series expansion to approximate solutions of the Hamilton–Jacobi equations. These controllers are applied to the problem of Earth-pointing spacecraft in circular orbits. The controllers are compared using both input–output and initial condition simulations, in an effort to gauge the improvements made possible by nonlinear feedback.
An evolutionary optimizing approach to neural network architecture for improving identification and modeling of aircraft nonlinear dynamics
Authors: Roudbari Alireza , Saghafi Fariborz
Published: November 2013

In this paper, modified genetic algorithm has been used as a simultaneous optimizer of recurrent neural network to improve identification and modeling of aircraft nonlinear dynamics. Weighted connections, network architecture, and learning rules are features that play important roles in the quality of neural networks training and their generalizability in order to model nonlinear systems. Therefore, the main focus of this paper is to apply appropriate evolutionary methods in order to simultaneously optimize the parameters of neural networks for the improvement identification and modeling of aircraft nonlinear dynamics. To validate this study, the results have been compared with the recorded data from a fourth generation highly maneuverable fighter aircraft flight test. Furthermore, having been compared to normal genetic algorithm, the results of the present study have showed significant improvement of the neural networks generalization which leads to better identification and modeling of aircraft nonlinear dynamics.
Impact point model predictive control of a spin-stabilized projectile with instability protection
Authors: Gross Matthew , Costello Mark
Published: November 2013

Most smart projectile control systems generate lateral control forces to guide the round to a target. Experience has shown that under the right combination of body orientation, translational velocity, and angular velocity, relatively low lateral control force inputs can induce instability of the round. To solve this problem, an additional control logic layer is appended to a nominal impact point flight control law to protect it from instability in these infrequent, but consequential situations. To highlight the newly developed control logic, a smart 155 mm spin-stabilized projectile equipped with a rotating paddle control mechanism is considered. For this example configuration, cross range maneuvering occasionally induces instability. Simulation results, using both rigid and multi-body nonlinear flight dynamics models, indicate that the addition of the instability protection layer in the control logic prevents projectile instability while not substantially altering target impact statistics. The nature of this protector design lends itself well to the use of a GPU to perform the calculations, greatly decreasing the computation time needed.
Mathematical modelling of peristaltic propulsion of viscoplastic bio-fluids
Authors: Tripathi D , Bég Osman A
Published: November 2013

This article studies theoretically the transportation of rheological viscoplastic fluids through physiological vessels by continuous muscle contraction and relaxation, that is, peristalsis. Both cases of planar and cylindrical physiological vessels are considered. A mathematical model is developed under long wavelength and low Reynolds number approximations. Expressions for axial velocity in core region, axial velocity in plug flow region, volume flow rate and pressure gradient in non-dimensional form are obtained. A comparative study of velocity profiles, pressure distribution, friction force and mechanical efficiency for different viscoplastic liquids is conducted. The influence of width of plug flow region, shear rate strain index and yield stress index on the pressure distribution, friction force and mechanical efficiency is elaborated. The study is relevant to gastric fluid mechanics and also non-Newtonian biomimetic pump hazardous waste systems exploiting peristaltic mechanisms.
A parametric finite element analysis of the compacted bone–cement interface following balloon kyphoplasty
Authors: Purcell Philip , Tyndyk Magdalena , McEvoy Fiona , Tiernan Stephen , Morris Seamus
Published: November 2013

Treating fractures of the spine is a major challenge for the medical community with an estimated 1.4 million fractures per annum worldwide. While a considerable volume of study exists on the biomechanical implications of balloon kyphoplasty, which is used to treat these fractures, the influence of the compacted bone–cement region properties on stress distribution within the vertebral body remains unknown. The following article describes a novel method for modelling this compacted bone–cement region using a geometry-based approach in conjunction with the knowledge of the bone volume fractions for the native and compacted bone regions. Three variables for the compacted region were examined, as follows: (1) compacted thickness, (2) compacted region Young’s modulus and (3) friction coefficient. Results from the model indicate that the properties of the compacted bone–cement region can affect stresses in the cortical bone and cement by up to +28% and −40%, respectively. These findings demonstrate the need for further investigation into the effects of the compacted bone–cement interface using computational and experimental methods on multi-segment models.
Value predispositions as perceptual filters: Comparing of public attitudes toward nanotechnology in the United States and Singapore
Authors: Liang Xuan , Ho Shirley S. , Brossard Dominique , Xenos Michael A. , Scheufele Dietram A. , Anderson Ashley A. , Hao Xiaoming , He Xiaoyu
Published: November 2013

This study compares public attitudes toward nanotechnology in the United States and Singapore, using large-scale survey data in both countries. Results indicate that Singaporeans tend to be more knowledgeable about and familiar with nanotechnology than the U.S. public. Singaporeans tend to perceive greater benefits and fewer potential risks of nanotechnology, and to indicate greater support for government funding for nanotechnology than the U.S. public. Between the two countries, perceived familiarity with nanotechnology and the benefits and risks of the emerging technology tend to be interpreted differently through the lens of value predispositions (religiosity and deference to scientific authority) and therefore they indirectly affect public support. Specifically, the U.S. public tends to use religiosity to interpret benefits and Singaporeans are inclined to use religiosity to think about risks. Deference to scientific authority also moderates the impact of perceived familiarity with nanotechnology on funding support for the technology among the U.S. public.
Nacherzeugung, Nachverstehen: A phenomenological perspective on how public understanding of science changes by engaging with online media
Authors: Roth Wolff-Michael , Friesen Norm
Published: November 2013

It is widely acknowledged in science education that everyday understandings and evidence are generally inconsistent with the scientific view of the matter: “heartache” has little to do with matters cardiopulmonary, and a rising or setting sun actually reflects the movements of the earth. How then does a member of the general public, which in many areas of science is characterized as “illiterate” and “non-scientific,” come to regard something scientifically? Moreover, how do traditional unscientific (e.g., Ptolemaic) views continue their lives, even many centuries after scientists have overthrown them in what are termed scientific (e.g., Copernican) revolutions? In this study, we develop a phenomenological perspective, using Edmund Husserl’s categories of Nacherzeugung and Nachverstehen, which provide descriptive explanations for our observations. These observations are contextualized in a case study using online video and historical materials concerning the motions of the heart and blood to exemplify our explanations.
Equivalent fractional Kelvin model and experimental study on viscoelastic damper
Authors: Xu Zhao-Dong , Xu Chao , Hu Jian
Published: November 2013

In this paper, tests on viscoelastic (VE) dampers are carried out, and the results indicate that VE dampers have high energy dissipation capacity and excellent anti-fatigue properties. To clarify the mechanical properties of VE dampers, a new mathematical model, named the equivalent fractional Kelvin model, which considers temperature and frequency effects simultaneously, is proposed. The numerical results using this model are in good agreement with experimental results. Then, through analysis on a five-story reinforced concrete frame structure with and without VE dampers, it is found that the seismic responses of the structure with VE dampers are significantly reduced and VE dampers have high energy dissipation capacity.