bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular proliferation in the nasal septal cartilage of juvenile minipigs
Authors: Al Dayeh Ayman A. , Herring Susan W.
Published: October 2014

The growth of the nasal septal cartilage is believed to be a driving force of midfacial growth. Cellular proliferation is an important contributor to growth of the cartilage, but this factor has been rarely investigated. The current study was undertaken to assess the proliferation and cellular density in the septal cartilage of fast‐growing juvenile minipigs. Six minipigs averaging 4.4 ± 1 months old were injected with 5′‐bromo‐2′‐deoxyuridine (BrdU), a thymidine analog, 24 h before death. The septal cartilage was sectioned in the coronal plane and reacted for BrdU. The proliferative index (number of BrdU‐positive chondrocytes/total number of chondrocytes) and cellular density (number of cells mm−2) of various locations of the septum were measured and compared in order to determine overall proliferation rate and whether regional variations in proliferative activity and cellular density are present. To provide a time perspective to the problem of midfacial growth, the lengths of the nasal bone and the palate were measured in a collection of 61 dry skulls of minipigs aged 1–8 months. Results showed that the septal chondrocytes were proliferating at a surprisingly high rate (~21%). The proliferative index was higher in the ventral and middle compared with the dorsal locations, and in the central cartilage compared with the perichondrium. No difference in proliferative index was found between the anterior and posterior parts of the septum. Cellular density was higher in the perichondrium than in the central cartilage. Within the central cartilage there was a trend for higher cellular density anteriorly. In conclusion, the rapidly growing midface of juvenile minipigs is associated with a high rate of septal proliferation, especially in the ventral half of the cartilage.
Comparison of direct and indirect occlusal contact examinations with different clenching intensities
Authors: Komiyama O. , Obara R. , Iida T. , Asano T. , Masuda M. , Uchida T. , De Laat A. , Kawara M.
Published: October 2014

The aims of this study were to examine the change of occlusal contact area following the increment of clenching intensity using silicone materials and electromyography (EMG) in normal subjects and to compare direct intra‐oral examination with indirect examination using dental casts mounted by means of two impression methods. Participants were 7 men and 5 women with no more than one missing tooth per quadrant and no pain in the head and neck region. During the task, intercuspal position was maintained with minimal force, 20% maximum voluntary contraction (MVC) and 40% MVC using electromyography visual feedback. Three types of occlusal contact examinations were performed with the aid of blue silicone material in randomised order: (i) intra‐oral direct occlusal contact examination (DE), (ii) indirect occlusal contact examination with dental casts using conventional impression method (IEC) and (iii) using occlusal impression method (IEO). Total occlusal contact area during DE and IEO significantly increased from baseline to 20% MVC and from baseline to 40% MVC, but not during IEC. Total occlusal contact area during DE in all tooth clenching conditions was significantly larger compared to IEO and IEC (P < 0·05). At 40% MVC, total occlusal contact area during IEO was significantly larger than during IEC (P < 0·05). These findings suggest that indirect occlusal contact examinations may not accurately reflect the intra‐oral occlusal condition. If the intra‐oral condition is reproduced using dental casts, these findings also suggest the occlusal impression method was more accurate compared to the conventional method (240 words).
Low ambient temperature elevates plasma triiodothyronine concentrations while reducing digesta mean retention time and methane yield in sheep
Authors: Barnett M. C. , McFarlane J .R. , Hegarty R. S.
Published: October 2014

Ruminant methane yield (MY) is positively correlated with mean retention time (MRT) of digesta. The hormone triiodothyronine (T3), which is negatively correlated with ambient temperature, is known to influence MRT. It was hypothesised that exposing sheep to low ambient temperatures would increase plasma T3 concentration and decrease MRT of digesta within the rumen of sheep, resulting in a reduction of MY. To test this hypothesis, six Merino sheep were exposed to two different ambient temperatures (cold treatment, 9 ± 1 °C; warm control 26 ± 1 °C). The effects on MY, digesta MRT, plasma T3 concentration, CO2 production, DM intake, DM digestibility, change in body weight (BW), rumen volatile fatty acid (VFA) concentrations, estimated microbial protein output, protozoa abundance, wool growth, water intake, urine output and rectal temperature were studied. Cold treatment resulted in a reduction in MY (p < 0.01); digesta MRT in rumen (p < 0.01), hindgut (p = 0.01) and total digestive tract (p < 0.01); protozoa abundance (p < 0.05); and water intake (p < 0.001). Exposure to cold temperature increased plasma T3 concentration (p < 0.05), CO2 production (p = 0.01), total VFA concentrations (p = 0.03) and estimated microbial output from the rumen (p = 0.03). The rate of wool growth increased (p < 0.01) due to cold treatment, but DM intake, DM digestibility and BW change were not affected. The results suggest that exposure of sheep to cold ambient temperatures reduces digesta retention time in the gastrointestinal tract, leading to a reduction in enteric methane yield. Further research is warranted to determine whether T3 could be used as an indirect selection tool for genetic selection of low enteric methane‐producing ruminants.
Dynamic modelling of hepatitis C virus transmission among people who inject drugs: a methodological review
Authors: Cousien A. , Tran V. C. , Deuffic‐Burban S. , Jauffret‐Roustide M. , Dhersin J.‐S. , Yazdanpanah Y.
Published: October 2014

Equipment sharing among people who inject drugs (PWID) is a key risk factor in infection by hepatitis C virus (HCV). Both the effectiveness and cost–effectiveness of interventions aimed at reducing HCV transmission in this population (such as opioid substitution therapy, needle exchange programmes or improved treatment) are difficult to evaluate using field surveys. Ethical issues and complicated access to the PWID population make it difficult to gather epidemiological data. In this context, mathematical modelling of HCV transmission is a useful alternative for comparing the cost and effectiveness of various interventions. Several models have been developed in the past few years. They are often based on strong hypotheses concerning the population structure. This review presents compartmental and individual‐based models to underline their strengths and limits in the context of HCV infection among PWID. The final section discusses the main results of the papers.
Endoscopic Assessment of the Duodenum in Dogs with Inflammatory Bowel Disease
Authors: Slovak J.E. , Wang C. , Morrison J.A. , Deitz K.L. , LeVine D.N. , Otoni C. , King R.R. , Gerber L.E. , Hanson K.R. , Lundberg A.P. , Jergens A.E.
Published: October 2014

Background

Endoscopy is performed for direct inspection of the mucosa and acquisition of biopsies in dogs with inflammatory bowel disease (IBD).

Aim

To evaluate the interobserver agreement in the endoscopic assessment of duodenal mucosa in dogs withIBD.

Methods

Thirty‐five archived endoscopic images of grossly normal (n = 6) and inflamed (n = 29) duodenal mucosa were displayed to 3 expert and 5 trainee endoscopists. Each image was assessed independently by endoscopists for mucosal abnormalities using established indices (of hyperemia, granularity, friability, lymphatic dilatation, and erosions) or interpreted as normal mucosa (trial 1). A repeated trial (trial 2) was performed with the same images presented in random order 1 month later, and accompanied by a visual template.

Results

There was slight interobserver agreement in initial mucosal assessment for expert and trainee endoscopists in trial 1 (kappa ≤ 0.02,P > .05). Interobserver agreement improved in trial 2 for both expert and trainee endoscopists (kappa = 0.2,P > .05) for experts and (P < .05) for trainees. There was a significant (P < .01) improvement in trainee endoscopy scores of lesions from trial 1 to trial 2. Regression analysis showed a significant (P < .01) difference between expert versus trainee endoscopy scores in trial 1. Repeat lesion assessment aided by use of a visual template (trial 2) improved the overall scores of trainee endoscopists to near that of expert endoscopists (P = .06).

Conclusions and Clinical Importance

Interobserver agreement ofIBDmucosal appearance from endoscopic findings benefitted from operator experience.
Relationship between Serum Symmetric Dimethylarginine Concentration and Glomerular Filtration Rate in Cats
Authors: Braff J. , Obare E. , Yerramilli M. , Elliott J. , Yerramilli M.
Published: October 2014

Background

Direct measurement of glomerular filtration rate (GFR) is the preferred method to assess renal function in cats, but it is not widely used in the diagnosis of chronic kidney disease (CKD). In cats with CKD, symmetric dimethylarginine (SDMA) has been shown to increase and to correlate with plasma creatinine concentrations.

Hypothesis

In cats, reduced GFR corresponds with increased serum SDMA concentration.

Animals

The study group consisted of ten client‐owned cats whose GFR had been measured previously. Cats ranged in age from 11.1 to 16.9 years; both azotemic and nonazotemic animals were included.

Methods

Glomerular filtration rate was determined for each cat by plasma iohexol clearance using the three sample slope‐intercept method, and serum SDMA concentration was measured by liquid chromatography‐mass spectrometry.

Results

A linear relationship was observed between GFR and the reciprocal of serum SDMA concentration (R2 = 0.82, P < .001). A similar relationship was found between GFR and the reciprocal of plasma creatinine concentration (R2 = 0.81, P < .001).

Conclusions and Clinical Importance

Increased serum SDMA concentrations were observed in cats with reduced renal function as determined by direct measurement of GFR. This finding indicates that SDMA could have clinical applications in the diagnosis of CKD in cats.
Developing a critical care bowel management assessment tool to manage faecal incontinence
Authors: Peart Joanna , Richardson Annette
Published: October 2014

Background

Critical care patients with faecal incontinence are at high risk of developing moisture lesions, pressure ulcers and secondary infection.

Aims

The aims of this quality improvement programme were to identify the level of harm caused by faecal incontinence in critical care, and to review current critical care nursing practice on the use of bowel management systems, with the intent to implement changes to prevent delayed insertion.

The improvement programme

A four‐step approach was used to guide the improvement programme. A total of seven case studies across three critical care units were reviewed and information was collected on stool type and frequency, duration of diarrhoea and skin integrity prior to bowel management system insertion.

Discussion

Critical care nurses may not always use a consistent approach to the assessment of patients at risk of moisture or pressure damage due to faecal incontinence. Lack of knowledge about the maintenance of bowel management systems was viewed as a likely reason for the inconsistent approach. A Critical Care Bowel Management Assessment Tool was created, to contribute towards a more standardised approach to bowel assessment and management.

Conclusions

Inadequate assessment and management of faecal incontinence may have implications for critically ill patients. Further evaluation is required in order to demonstrate over time whether the changes made, as a result of this quality improvement programme, have led to sustainable improvement.
Defining patient deterioration through acute care and intensive care nurses' perspectives
Authors: Lavoie Patrick , Pepin Jacinthe , Alderson Marie
Published: October 2014

Aim

To explore the variations between acute care and intensive care nurses' understanding of patient deterioration according to their use of this term in published literature.

Background

Evidence suggests that nurses on wards do not always recognize and act upon patient deterioration appropriately. Even if resources exist to call for intensive care nurses' help, acute care nurses use them infrequently and the problem of unattended patient deterioration remains.

Design

Dimensional analysis was used as a framework to analyze papers retrieved in a nursing‐focused database.

Method

A thematic analysis of 34 papers (2002–2012) depicting acute care and intensive care unit nurses' perspectives on patient deterioration was conducted.

Findings

No explicit definition of patient deterioration was retrieved in the papers. There are variations between acute care and intensive care unit nurses' accounts of this concept, particularly regarding the validity of patient deterioration indicators. Contextual factors, processes and consequences are also explored.

Conclusions

From the perspectives of acute care and intensive care nurses, patient deterioration can be defined as an evolving, predictable and symptomatic process of worsening physiology towards critical illness. Contextual factors relating to acute care units (ACU) appear as barriers to optimal care of the deteriorating patient. This work can be considered as a first effort in modelling the concept of patient deterioration, which could be specific to ACU.

Relevance to clinical practice

The findings suggest that it might be relevant to include subjective indicators of patient deterioration in track and trigger systems and educational efforts. Contextual factors impacting care for the deteriorating patient could be addressed in further attempts to deal with this issue.
Do Teaching General Practitioners' Fear‐Avoidance Beliefs Influence Their Management of Patients with Low Back Pain?
Authors: Gremeaux Vincent , Coudeyre Emmanuel , Viviez Thomas , Bousquet Philippe Jean , Dupeyron Arnaud
Published: October 2014

Objectives

To describe fear‐avoidance beliefs about low back pain (LBP) in a sample of teaching general practitioners (TGPs) and to investigate the impact on following the guidelines for LBP.

Methods

A sample of 112 French TGPs were contacted to complete a self‐administered questionnaire including socio‐demographic and professional data, personal history of LBP, CME about LBP and usual practices, and their low back pain beliefs using the Fear‐Avoidance Beliefs Questionnaire (FABQ) and the Back Belief Questionnaire (BBQ).

Results

Forty‐seven responded, 48% treated more than 10 LBP patients per month, and 45% participated in an educational session on LBP during the previous 3 years. Seventy percent reported a previous episode of acute LBP, while 30% suffered from chronic LBP. The median scores for the FABQ‐phys and work were 8 (4 to 10) and 17 (11 to 21), and 35 (31 to 38) for the BBQ. There were no correlations between age or years of practice and FABQ scores. TGPs suffering more than 1 acute LBP episode per month had a lower BBQ score (P < 0.05). Those prescribing more imaging exams in acute LBP had higher FABQ and lower BBQ scores, while those who recommended rest in both acute and chronic LBP had a higher FABQ‐phys score.

Discussion

Teaching general practitioners' fear‐avoidance beliefs about LBP are lower than previously reported by their GP colleagues but still negatively influence the way they follow guidelines for LBP patients. This may influence the way they teach the management of LBP.
Photoactive Chitosan: A Step Toward a Green Strategy for Pollutant Degradation
Authors: Walalawela Niluksha , Greer Alexander
Published: October 2014

This article is a highlight of the paper by Ferrari et al. in this issue of Photochemistry and Photobiology. It describes the innovative use of rose bengal‐conjugated chitosan as a reusable green catalyst that photo‐degrades phenolic compounds in aqueous media, and thereby has decontamination potential of polluted waters. Whether a next‐generation photoactive polymer that produces singlet oxygen is a solution to pollutant degradation can be argued. It is as yet unclear what polymeric sensitizer would be practical on a large scale. Nonetheless pursuing this goal is worthwhile.
A proteomic analysis of rice seed germination as affected by high temperature and ABA treatment
Authors: Liu Shu‐Jun , Xu Heng‐Heng , Wang Wei‐Qing , Li Ni , Wang Wei‐Ping , Møller Ian Max , Song Song‐Quan
Published: October 2014

Seed germination is a critical phase in the plant life cycle, but the specific events associated with seed germination are still not fully understood. In this study, we used two‐dimensional gel electrophoresis followed by mass spectrometry to investigate the changes in the proteome during imbibition of Oryza sativa seeds at optimal temperature with or without abscisic acid (ABA) and high temperature (germination thermoinhibition) to further identify and quantify key proteins required for seed germination. A total of 121 protein spots showed a significant change in abundance (1.5‐fold increase/decrease) during germination under all conditions. Among these proteins, we found seven proteins specifically associated with seed germination including glycosyl hydrolases family 38 protein, granule‐bound starch synthase 1, Os03g0842900 (putative steroleosin‐B), N‐carbamoylputrescine amidase, spermidine synthase 1, tubulin α‐1 chain and glutelin type‐A; and a total of 20 imbibition response proteins involved in energy metabolism, cell growth, cell defense and storage proteins. High temperature inhibited seed germination by decreasing the abundance of proteins involved in methionine metabolism, amino acid biosynthesis, energy metabolism, reserve degradation, protein folding and stress responses. ABA treatment inhibited germination and decreased the abundance of proteins associated with methionine metabolism, energy production and cell division. Our results show that changes in many biological processes including energy metabolism, protein synthesis and cell defense and rescue occurred as a result of all treatments, while enzymes involved in methionine metabolism and weakening of cell wall specifically accumulated when the seeds germinated at the optimal temperature.
Differences in cold hardiness, carbohydrates, dehydrins and related gene expressions under an experimental deacclimation and reacclimation in Prunus persica
Authors: Shin Hyunsuk , Oh Youngjae , Kim Daeil
Published: October 2014

To boost our understanding of a recent outbreak of freezing injury, we sought to confirm distinctive features between the shoot tissues of the peach (Prunus persica) cultivars Daewol and Kiraranokiwami by mimicking unseasonable changes of temperatures that occur in the early spring through repeated deacclimation and reacclimation treatments. Patterns of cold hardiness declined dramatically during the deacclimation and rose during the reacclimation in both cultivars. Our results indicated that ‘Daewol’ possessed higher capacity in response to repeated deacclimation and reacclimation treatments than ‘Kiraranokiwami’. ‘Daewol’ showed more sensitive changes in the carbohydrates in response to warm and low temperatures compared with ‘Kiraranokiwami’. ‘Daewol’ indicated almost similar repeated down‐ and up‐patterns in soluble sugar content in response to repeated deacclimation and reacclimation, whereas it indicated repeated up‐ and down‐patterns in starch content. However, ‘Kiraranokiwami’ showed a progressive increase in the soluble sugar content and a progressive decrease in starch content. Notably, patterns of accumulation of a 60‐kDa dehydrin protein encoded by the PpDhn1 gene were confirmed through western blotting and paralleled fluctuations of cold hardiness in both cultivars. Expression of this dehydrin was weak in both cultivars during deacclimation but its band intensity increased during reacclimation. Changes in related genes (β‐amylase, PpDhn1, PpDhn2 and PpDhn3) were positively correlated with changes in cold hardiness throughout the experiment. Our results indicate that recent repeated warm periods may cause premature deacclimation in the early spring, and that more cold‐tolerant cultivar may be more resilient to freezing injury caused by unstable temperature conditions.
Helping Callers to the National Suicide Prevention Lifeline Who Are at Imminent Risk of Suicide: The Importance of Active Engagement, Active Rescue, and Collaboration Between Crisis and Emergency Services
Authors: Draper John , Murphy Gillian , Vega Eduardo , Covington David W. , McKeon Richard
Published: October 2014

In 2012, theSAMHSA‐fundedNationalSuicidePreventionLifeline (Lifeline) completed implementation of the first nationalPolicy forHelpingCallers atImminentRisk ofSuicide across its network of crisis centers. The policy sought to: (1) provide a clear definition of imminent risk; (2) reflect the state of evidence, field experience, and promising practices related to reducing imminent risk through hotline interventions; and (3) provide a uniform policy and approach that could be applied across crisis center settings. The resulting policy established three essential principles: active engagement, active rescue, and collaboration between crisis and emergency services. A sample of the research and rationale that underpinned the development of this policy is provided here. In addition, policy implementation, challenges and successes, and implications for interventions to helpLifeline callers at imminent risk of suicide are detailed.
Wayne School of Engineering: Case Study of a Rural Inclusive STEM‐Focused High School
Authors: Peters Burton Erin , Kaminsky Samuel E. , Lynch Sharon , Behrend Tara , Han Edmund , Ross Kathleen , House Ann
Published: October 2014

Rural schools face challenges that are often different than nonrural schools. Resource constraints are particularly acute in rural schools, and they struggle to offer advanced courses and extracurricular programs. The purpose of this paper is to present a descriptive, instrumental case study of an inclusive rural science, technology, engineering, and mathematics school that has successfully dealt with challenges and offers an innovative and productive learning environment, despite limited resources. For this study, a variety of on‐site and off‐site data collection techniques were used such as focus groups, classroom observation protocols, and surveys. Wayne School of Engineering (WSE) overcomes resource barriers by matching their schedule to the local community college, upgrading the rigor of their high school classes and facilitating student transition to college. WSE also requires extracurricular research projects that help students see the relevance of their in class learning, build 21st century skills, and connect to partners outside of the school. Faced with limited budgetary, technological, and logistical resources, WSE administrators, teachers, and students work collectively to overcome these barriers and provide high‐quality education by finding ways to blur the lines of traditional secondary schools.
Immunogenicity and safety of a two‐dose live attenuated varicella vaccine given to adults following autologous hematopoietic stem cell transplantation
Authors: Sasadeusz J. , Prince H.M. , Schwarer A. , Szer J. , Stork A. , Bock H.L. , Povey M. , Nicholson O. , Innis B.L.
Published: October 2014

Background

Immunogenicity and safety of varicella vaccine (Varilrix™ [Oka‐RIT]; GlaxoSmithKline Vaccines) in adults who had undergone autologous hematopoietic stem cell transplantation (HSCT) were assessed (September 2003 to September 2007; NCT00792623).

Methods

Two Oka‐RIT doses were given at 4.5 and 6.5 months post transplantation. Humoral immune responses were assessed using an immunofluorescence assay (anti‐varicella zoster virus [VZV] antibody; cutoff 1:4) after each vaccine dose. Solicited local (8 day) and general (43 day), unsolicited (until day 43) adverse events (AEs) after each vaccine dose and serious adverse events (SAEs) (until 17.5 months post dose 2) were recorded.

Results

Of 45 patients, 19 were included in the according to protocol cohort for immunogenicity; 15 patients had pre‐ and post‐vaccination serum samples positive for anti‐VZV antibodies. Vaccine responses (anti‐VZV antibody titer ≥1:4 in seronegative patients, and ≥4‐fold increase in anti‐VZV antibody titer in seropositive patients) were elicited by only 2 patients 2 months post dose 1, and by a single patient 1.5 months post dose 2. Although no major safety signals were detected, any and Grade 3 solicited AEs that were causally related to vaccination were reported by 44.8% and 10.3% patients, respectively. During the 43‐day follow‐up period, 3 patients developed varicella‐like rash (1 vaccine‐type VZV). Beyond 43 days, herpes zoster was reported in 2 patients and wild‐type varicella infection in 2 patients (1 was breakthrough infection). Four non‐fatal SAEs were reported by patients and considered causally unrelated to vaccination.

Conclusion

Oka‐RIT was poorly immunogenic but safe when given to adults up to 6 months post autologous HSCT, and alternative strategies are required to prevent VZV‐associated complications in these populations.
The cell wall‐targeted purple acid phosphatase AtPAP25 is critical for acclimation of Arabidopsis thaliana to nutritional phosphorus deprivation
Authors: Del Vecchio Hernan A. , Ying Sheng , Park Joonho , Knowles Vicki L. , Kanno Satomi , Tanoi Keitaro , She Yi‐Min , Plaxton William C.
Published: October 2014

Plant purple acid phosphatases (PAPs) belong to a relatively large gene family whose individual functions are poorly understood. Three PAP isozymes that are up‐regulated in the cell walls of phosphate (Pi)‐starved (−Pi) Arabidopsis thaliana suspension cells were purified and identified by MS as AtPAP12 (At2g27190), AtPAP25 (At4g36350) and AtPAP26 (At5g34850). AtPAP12 and AtPAP26 were previously isolated from the culture medium of −Pi cell cultures, and shown to be secreted by roots of Arabidopsis seedlings to facilitate Pi scavenging from soil‐localized organophosphates. AtPAP25 exists as a 55 kDa monomer containing complex NX(S/T) glycosylation motifs at Asn172, Asn367 and Asn424. Transcript profiling and immunoblotting with anti‐AtPAP25 immune serum indicated that AtPAP25 is exclusively synthesized under −Pi conditions. Coupled with potent mixed‐type inhibition of AtPAP25 by Pi (I50 = 50 μm), this indicates a tight feedback control by Pi that prevents AtPAP25 from being synthesized or functioning as a phosphatase except when Pi levels are quite low. Promoter–GUS reporter assays revealed AtPAP25 expression in shoot vascular tissue of −Pi plants. Development of an atpap25 T‐DNA insertion mutant was arrested during cultivation on soil lacking soluble Pi, but rescued upon Pi fertilization or complementation with AtPAP25. Transcript profiling by quantitative RT‐PCR indicated that Pi starvation signaling was attenuated in the atpap25 mutant. AtPAP25 exhibited near‐optimal phosphatase activity with several phosphoproteins and phosphoamino acids as substrates. We hypothesize that AtPAP25 plays a key signaling role during Pi deprivation by functioning as a phosphoprotein phosphatase rather than as a non‐specific scavenger of Pi from extracellular P‐monoesters.
Passive/Active Autoparametric Cantilever Beam Absorber With Piezoelectric Actuator for a Two-Story Building-Like Structure
Authors: Silva-Navarro Gerardo , Abundis-Fong Hugo F.
Published: October 2014

This work deals with the design and experimental evaluation of a passive/active cantilever beam autoparametric vibration absorber mounted on a two-story building-like structure (primary system), with two rigid floors connected by flexible columns. The autoparametric vibration absorber consists of a cantilever beam with a piezoelectric patch actuator, cemented to its base, mounted on the top of the structure and actively controlled through an acquisition system. The overall system is then a coupled nonlinear oscillator subjected to sinusoidal excitation in the neighborhood of its external and internal resonances. The addition of the piezoelectric patch actuator to the cantilever beam absorber makes active the passive vibration absorber, thus enabling the possibility to control its equivalent stiffness and damping and, as a consequence, the implementation of an active vibration control scheme able to preserve, as possible, the autoparametric interaction as well as to compensate varying excitation frequencies and parametric uncertainty.
Pole Placement for Single-Input Linear System by Proportional-Derivative State Feedback
Authors: Abdelaziz Taha H. S.
Published: October 2014

This paper deals with the direct solution of the pole placement problem for single-input linear systems using proportional-derivative (PD) state feedback. This problem is always solvable for any controllable system. The explicit parametric expressions for the feedback gain controllers are derived which describe the available degrees of freedom offered by PD state feedback. These freedoms are utilized to obtain closed-loop systems with small gains. Its derivation is based on the transformation of linear system into control canonical form by a special coordinate transformation. The solving procedure results into a formula similar to Ackermann’s one. In the present work, both time-invariant and time-varying linear systems are treated. The effectiveness of the proposed method is demonstrated by the simulation examples of both time-invariant and time-varying systems.
A New Experimental Facility to Investigate Combustor–Turbine Interactions in Gas Turbines With Multiple Can Combustors
Authors: Luque S. , Kanjirakkad V. , Aslanidou I. , Lubbock R. , Rosic B. , Uchida S.
Published: October 2014

This paper describes a new modular experimental facility that was purpose-built to investigate flow interactions between the combustor and first stage nozzle guide vanes (NGVs) of heavy duty power generation gas turbines with multiple can combustors. The first stage turbine NGV is subjected to the highest thermal loads of all turbine components and therefore consumes a proportionally large amount of cooling air that contributes detrimentally to the stage and cycle efficiency. It has become necessary to devise novel cooling concepts that can substantially reduce the coolant air requirement but still allow the turbine to maintain its aerothermal performance. The present work aims to aid this objective by the design and commissioning of a high-speed linear cascade, which consists of two can combustor transition ducts and four first stage NGVs. This is a modular nonreactive air test platform with engine realistic geometries (gas path and near gas path), cooling system, and boundary conditions (inlet swirl, turbulence level, and boundary layer). The paper presents the various design aspects of the high pressure (HP) blow down type facility, and the initial results from a wide range of aerodynamic and heat transfer measurements under highly engine realistic conditions.
Analysis of Azimuthal Thermo-acoustic Modes in Annular Gas Turbine Combustion Chambers
Authors: Bothien Mirko R. , Noiray Nicolas , Schuermans Bruno
Published: October 2014

Modern gas turbine combustors operating in lean-premixed mode are prone to thermo-acoustic instabilities. In annular combustion chambers, usually azimuthal acoustic modes are the critical ones interacting with the flame. In case of constructive interference, high amplitude oscillations might result. In this paper, the azimuthal acoustic field of a full-scale engine is investigated in detail. The analyses are based on measurements in a full-scale gas turbine, analytical models to derive the system dynamics, as well as simulations performed with an in-house 3d nonlinear network model. It is shown that the network model is able to reproduce the behavior observed in the engine. Spectra, linear growth rates, as well as the statistics of the system's dynamics can be predicted. A previously introduced algorithm is used to extract linear growth rates from engine and model time domain data. The method's accuracy is confirmed by comparison of the routine's results to analytically determined growth rates from the network model. The network model is also used to derive a burner staging configuration, resulting in the decrease of linear growth rate and thus an increase of engine operation regime; model predictions are verified by full-scale engine measurements. A thorough investigation of the azimuthal modes statistics is performed. Additionally, the network model is used to show that an unfavorable flame temperature distribution with an amplitude of merely 1% of the mean flame temperature can change the azimuthal mode from dominantly rotating to dominantly standing. This is predicted by the network model that only takes into account flame fluctuations in axial direction.
Hysteretic Rubber Friction: Application of Persson's Theories to Grosch's Experimental Results
Authors: Fina E. , Gruber P. , Sharp R. S.
Published: October 2014

This paper revisits Grosch's work on rubber friction with Persson's contact theory. Persson's model is implemented to replicate Grosch's experiments on silicon carbide paper and compute the physical mechanism that Grosch identified as one of the main contributors to rubber friction: deformation friction. Grosch did not provide all rubber compound and surface characteristics required for the simulation work and, in order to obtain a full data set, the missing properties were adapted from literature sources and from measurements. The simulation results show that the deformation contribution is modeled correctly by Persson's model in terms of peak magnitude and sliding velocity at which the peak is located. On the contrary, poor correlation is found for the shape of the deformation friction master curve.
Numerical Analysis for Elucidation of Nonlinear Frictional Characteristics of a Deformed Erythrocyte Moving on a Plate in Medium Subject to Inclined Centrifugal Force
Authors: Oshibe Takashi , Hayase Toshiyuki , Funamoto Kenichi , Shirai Atsushi
Published: October 2014

Complex interactions between blood cells, plasma proteins, and glycocalyx in the endothelial surface layer are crucial in microcirculation. To obtain measurement data of such interactions, we have previously performed experiments using an inclined centrifuge microscope, which revealed that the nonlinear velocity-friction characteristics of erythrocytes moving on an endothelia-cultured glass plate in medium under inclined centrifugal force are much larger than those on plain or material-coated glass plates. The purpose of this study was to elucidate the nonlinear frictional characteristics of an erythrocyte on plain or material-coated glass plates as the basis to clarify the interaction between the erythrocyte and the endothelial cells. We propose a model in which steady motion of the cell is realized as an equilibrium state of the force and moment due to inclined centrifugal force and hydrodynamic flow force acting on the cell. Other electrochemical effects on the surfaces of the erythrocyte and the plate are ignored for the sake of simplicity. Numerical analysis was performed for a three-dimensional flow of a mixture of plasma and saline around a rigid erythrocyte model of an undeformed biconcave shape and a deformed shape with a concave top surface and a flat bottom surface. A variety of conditions for the concentration of plasma in a medium, the velocity of the cell, and the minimum gap width and the angle of attack of the cell from the plate, were examined to obtain the equilibrium states. A simple flat plate model based on the lubrication theory was also examined to elucidate the physical meaning of the model. The equilibrium angle of attack was obtained only for the deformed cell model and was represented as a power function of the minimum gap width. A simple flat plate model qualitatively explains the power function relation of the frictional characteristics, but it cannot explain the equilibrium relation, confirming the computational result that the deformation of the cell is necessary for the equilibrium. The frictional characteristics obtained from the present computation qualitatively agree with those of former experiments, showing the validity of the proposed model.
Efficient Design-Optimization of Variable-Density Hexagonal Cellular Structure by Additive Manufacturing: Theory and Validation
Authors: Zhang Pu , Toman Jakub , Yu Yiqi , Biyikli Emre , Kirca Mesut , Chmielus Markus , To Albert C.
Published: October 2014

Cellular structures are promising candidates for additive manufacturing (AM) due to their lower material and energy consumption. In this work, an efficient method is proposed for optimizing the topology of variable-density cellular structures to be fabricated by certain AM process. The method gains accuracy by relating the cellular structure's microstructure to continuous micromechanics models and achieves efficiency through conducting continuum topology optimization at macroscopic scale. The explicit cellular structure is then finally reconstructed by mapping the optimized continuous parameters (e.g., density) to cell structural parameters (e.g., strut diameter). The proposed method is validated by both finite element analysis and experimental tests on specimens manufactured by stereolithography.
Residual Stress in the Welding Joint of Layered Cylindrical Vessels Including the Weld Clad Effect
Authors: Xu Shugen , Wang Chong , Zhao Yanling
Published: October 2014

Layered cylindrical vessels are widely used in process industries. The weld clad is applied before the girth welding of layered-to-layered sections. In this paper, a numerical method was used to predict residual stresses in a layered-to-layered joint with weld clad. The results showed that high residual stresses were generated in the weld and heat affect zone (HAZ), and a discontinuous stress distribution was generated. The through-wall axial residual stress at the weld centerline (WCL) was predominately tensile. The axial residual stress in each layer at the HAZ demonstrated a bending type distribution. The through-wall hoop residual stress at the WCL was predominately compressive in the V-groove zone, and it was tensile in the U-groove zone. The weld clad can decrease the peak residual stress in the tip of the interlayer gaps.
Red emission phosphor for real‐time skin dosimeter for fluoroscopy and interventional radiology
Authors: Nakamura Masaaki , Chida Koichi , Zuguchi Masayuki
Published: October 2014

Purpose:

There are no effective real‐time direct skin dosimeters for interventional radiology. Such a scintillation dosimeter would be available if there was a suitable red emission phosphor in the medical x‐ray range, since the silicon photodiode is a highly efficient device for red light. However, it is unknown whether there is a suitable red emission phosphor. The purpose of this study is to find a suitable red emission phosphor that can be used in x‐ray dosimeters.

Methods:

Five kinds of phosphors which emit red light when irradiated with electron beams or ultraviolet rays in practical devices were chosen. For the brightness measurement, phosphor was put into transparent plastic cells or coated onto plastic sheets. The phosphors were irradiated with medical range x‐rays [60–120 kV(peak), maximum dose rate of 160 ], and the emission was measured by a luminance meter. Several characteristics, such as brightness, dose rate dependence, tube voltage dependence, and brightness stability, were investigated.

Results:

The luminescence of Y V O4:Eu, (Y,Gd,Eu) BO3, and Y2O3:Eu significantly deteriorated by 5%–10% when irradiated with continuous 2 Gy x‐rays. The 0.5MgF2⋅3.5MgO⋅GeO2:Mn phosphor did not emit enough. Only the Y2O2S:Eu,Sm phosphor had hardly any brightness deterioration, and it had a linear relationship so that the x‐ray dose rate could be determined from the brightness with sufficient accuracy. For the tube voltage dependence of the Y2O2S:Eu,Sm phosphor, the brightness per unit dose rate with 120 kV(peak) x‐rays was 30% higher than that with 60 kV(peak) x‐rays.

Conclusions:

Five kinds of phosphors were chosen as an x‐ray scintillator for a real‐time direct skin dosimeter. The Y V O4:Eu, (Y,Gd,Eu)BO3, and Y2O3:Eu phosphors had brightness deterioration caused by the x‐rays. Only the Y2O2S:Eu,Sm phosphor had hardly any brightness deterioration, and it is a candidate for an x‐ray scintillator for such a skin dosimeter.
Phase synchronization analysis of prefrontal tissue oxyhemoglobin oscillations in elderly subjects with cerebral infarction
Authors: Han Qingyu , Li Zengyong , Gao Yuanjin , Li Wenhao , Xin Qing , Tan Qitao , Zhang Manyu , Zhang Yixun
Published: October 2014

Purpose:

This study aims to assess the phase relationship of prefrontal tissue oxyhemoglobin oscillations using wavelet phase coherence analysis of cerebral Delta [HbO2] signals in cerebral infarction (CI) patients during the resting state.

Methods:

Continuous recordings of near‐infrared spectroscopy signals were obtained from the left and right prefrontal lobes in 21 subjects with CI (Group CI, age: 76.6 ± 8.5 yr) and 21 healthy elderly subjects (Group Healthy, age: 69.0 ± 7.4 yr) during the resting state. The Group CI was further divide into two groups: CI with hypertension and CI without hypertension. The phase synchronization between left and right prefrontal Delta [HbO2] oscillations in four frequency intervals (I, 0.6–2 Hz; II, 0.145–0.6 Hz; III, 0.052–0.145 Hz; and IV, 0.021–0.052 Hz) was analyzed using wavelet phase coherence method.

Results:

The phase coherences in intervals III and IV were significantly lower in CI with hypertension than in healthy elderly subjects (F = 12.974, p = 0.001 for III and F = 10.073, p = 0.004 for interval IV). The phase coherence of CI without hypertension in interval III was significantly lower than in healthy elderly subjects (F = 9.909, p = 0.004). Also, the phase coherence in interval IV was significantly lower in CI with hypertension than in CI without hypertension (F = 5.665, p = 0.028). Also, the phase agreement in interval IV showed evident difference between Group CI with hypertension and without hypertension.

Conclusions:

The difference in phase characteristics of prefrontal tissue oxyhemoglobin oscillations between the CI patients and healthy elderly indicates altered phase synchronization. Moreover, the CI combined with hypertension would aggravate this process. This study provides new insight into the phase dynamics of cerebral oxygenation and may be useful in assessing the risk for stroke.
Measurement of bow tie profiles in CT scanners using a real‐time dosimeter
Authors: Whiting Bruce R. , Evans Joshua D. , Dohatcu Andreea C. , Williamson Jeffrey F. , Politte David G.
Published: October 2014

Purpose:

Several areas of computed tomography (CT) research require knowledge about the intensity profile of the x‐ray fan beam that is introduced by a bow tie filter. This information is considered proprietary by CT manufacturers, so noninvasive measurement methods are required. One method using real‐time dosimeters has been proposed in the literature. A commercially available dosimeter was used to apply that method, and analysis techniques were developed to extract fan beam profiles from measurements.

Methods:

A real‐time ion chamber was placed near the periphery of an empty CT gantry and the dose rate versus time waveform was recorded as the x‐ray source rotated about the isocenter. In contrast to previously proposed analysis methods that assumed a pointlike detector, the finite‐size ion chamber received varying amounts of coverage by the collimated x‐ray beam during rotation, precluding a simple relationship between the source intensity as a function of fan beam angle and measured intensity. A two‐parameter model for measurement intensity was developed that included both effective collimation width and source‐to‐detector distance, which then was iteratively solved to minimize the error between duplicate measurements at corresponding fan beam angles, allowing determination of the fan beam profile from measured dose‐rate waveforms. Measurements were performed on five different scanner systems while varying parameters such as collimation, kVp, and bow tie filters. On one system, direct measurements of the bow tie profile were collected for comparison with the real‐time dosimeter technique.

Results:

The data analysis method for a finite‐size detector was found to produce a fan beam profile estimate with a relative error between duplicate measurement intensities of <5%. It was robust over a wide range of collimation widths (e.g., 1–40 mm), producing fan beam profiles that agreed with a relative error of 1%–5%. Comparison with a direct measurement technique on one system produced agreement with a relative error of 2%–6%. Fan beam profiles were found to differ for different filter types on a given system and between different vendors.

Conclusions:

A commercially available real‐time dosimeter probe was found to be a convenient and accurate instrument for measuring fan beam profiles. An analysis method was developed that could handle a wide range of collimation widths by explicitly considering the finite width of the ion chamber. Relative errors in the profiles were found to be less than 5%. Measurements of five different clinical scanners demonstrate the variation in bow tie designs, indicating that generic bow tie models will not be adequate for CT system research.
Step-Count Guidelines for Children and Adolescents: A Systematic Review
Authors: da Silva Michael Pereira , Fontana Fabio Eduardo , Callahan Eric , Mazzardo Oldemar , De Campos Wagner
Published: October 2014

Background:

The aim of this systematic review was to identify the most optimal step-count cutoff for children and adolescents (5–19 years old) among guidelines currently available in the literature.

Methods:

The databases searched were PubMed, SportDiscus, Science Direct, Web of Science and LILACS. Studies were categorized into Health Cohort studies or Physical Activity (PA) Cohort studies according to the reference standard used. The quality of the studies was assessed using the QUADAS-2 instrument.

Results:

Six Health and 3 PA Cohort studies were included in the final pool of papers after Full Text reading. With the exception of a single study, studies demonstrated a high risk of methodological bias in at least 1 of the QUADAS-2 domains. Guidelines ranged from 10,000 to 16,000 steps/day for the Health studies (5–16 years old), and from 9,000 to 14,000 steps/day for PA studies (6–19 years old). Due to the high risk of methodological bias, none of the Health Cohort guidelines were endorsed. The PA Cohort study with the lowest risk of methodological bias suggested 12,000 steps/day for children and adolescents irrespective of gender.

Conclusion:

PA Cohort studies demonstrated lower risk of methodological bias than Health Cohort studies. The optimal youth step-count guideline of 12,000 steps/day was endorsed.