bluuebunny/crossref_metadata_2025 huggingface dataset:
Emergency Department Chlamydia Screening Through Partnership with the Public Health Department
Authors: Irvin Charlene Babcock , Nowak Bruce , Moore Maureen , Flynn Kevin , Vretta Catherine
Published: October 2009

Background:  The emergency department (ED) serves a population that may benefit from numerous screening initiatives but screening in the ED is challenging due to crowding as well as resource and time constraints. One option may be to collect specimens in the ED and then partner with the public health department (PHD) to analyze the specimens off‐site and arrange follow‐up treatment.

Objectives:  The objective was to explore the feasibility of chlamydia screening in females using a partnership model in which the ED is responsible for urine collection and the PHD is responsible for chlamydia testing, notification, and treatment.

Methods:  A collaborative partnership‐based chlamydia screening project was initiated at a large (90,000 visits/yr), urban, teaching ED from April 2007 to April 2008. Study information sheets were handed out to a convenience sample of eligible female patients and visitors (15–24 yr of age). Those wishing to participate provided a urine sample and follow‐up contact information. The information sheet also asked if they had either lower abdominal pain or vaginal discharge (affirmative answer for either was considered symptomatic). Specimens collected in the ED were retrieved by PHD staff for off‐site testing. The PHD contacted those participants testing positive using the patient provided contact information and arranged for treatment.

Results:  Of the 633 women offered screening, 296 (47%) agreed to testing and provided samples. Of the 296 tested, 38 (12.8%) were positive for chlamydia infection, and 25 (66%) received follow‐up and treatment; 13 could not be contacted through information they provided. A higher percentage of symptomatic subjects (23 of 115, or 20%) tested positive for chlamydia than asymptomatic subjects (15 of 181, or 8.3%; p < 0.01).

Conclusions:  This study demonstrates the feasibility of an ED–PHD partnership for chlamydia screening in young women. This model can potentially be applied to other initiatives and may improve public health screening without creating significant additional burdens for crowded EDs.
Six‐month Follow‐up of a Brief Intervention on Self‐reported Safety Belt Use Among Emergency Department Patients
Authors: Fernandez William G. , Winter Michael R. , Mitchell Patricia M. , Bullock Holly , Donovan Jacqueline , George Jill St. , Feldman James A. , Gallagher Susan S. , McKay Mary Pat , Bernstein Edward , Colton Theodore
Published: October 2009

Objectives:  Safety belt use (SBU) reduces motor vehicle deaths by 45%. We previously reported that a brief intervention improved self‐reported SBU among emergency department (ED) patients at 3 months. We sought to determine if these effects were sustained at 6 months postenrollment.

Methods:  This was a prospective, randomized controlled trial of adult patients (age ≥ 21 years) at an academic medical center ED from February 2006 to May 2006. Patients were systematically sampled for self‐reported SBU. Those with self‐reported SBU less than “always” were asked to participate. Subjects were surveyed at baseline with a nine‐item series of situational SBU questions scored on a five‐point Likert scale (e.g., 5 = always, 1 = never). This nine‐item average comprised the mean SBU score. Subjects were randomized to a control group (CG) and an intervention group (IG). The CG received an injury prevention brochure; the IG received a brief motivation interview by a trained interventionist and the brochure. Subjects were phoned at 3 and 6 months to determine interval change in SBU scores via a standard script. Repeated‐measures analysis of covariance and t‐tests were used to analyze trends in mean SBU scores between groups, as well as to test mean changes in SBU scores from the 3‐ to 6‐month intervals.

Results:  Of 432 eligible patients, 292 enrolled (mean age = 35 years, SD ± 11.2 years; 61% male). At baseline, there were no significant demographic differences; the IG (n = 147) and CG (n = 145) had similar mean SBU scores (2.8 vs. 2.6, p = 0.31), and 66% (n = 96 in each) completed both 3‐ and 6‐month follow‐up. The mean SBU score at 6 months in the IG was greater than in the CG group (3.6 vs. 2.9, p < 0.001), as were the mean SBU score differences from baseline (IG = 0.84 vs. CG = 0.29, p < 0.001). These differences were sustained from the 3‐month interval (IG = −0.02 vs. CG = −0.06, p > 0.05).

Conclusions:  The previously reported finding that ED patients who received a brief motivation interview reported higher SBU scores at 3 months compared to a CG was sustained at 6‐month follow‐up. Although limited by self‐report, a brief intervention may enhance lasting SBU behavior among high‐risk ED patients.
Using innovative group‐work activities to enhance the problem‐based learning experience for dental students
Authors: Grady R. , Gouldsborough I. , Sheader E. , Speake T.
Published: October 2009

Problem‐based learning (PBL) in medical and dental curricula is now well established, as such courses are seen to equip students with valuable transferable skills (e.g. problem‐solving or team‐working abilities), in addition to knowledge acquisition. However, it is often assumed that students improve in such skills without actually providing direct opportunity for practice, and without giving students feedback on their performance. ‘The Manchester Dental Programme’ (TMDP) was developed at The University of Manchester, UK as a 5‐year, integrated enquiry‐led curriculum. The existing PBL course was redesigned to include a unique, additional PBL session (‘Session 4’) that incorporated an activity for the group to complete, based on the subject material covered during student self‐study. A summative mark was awarded for each activity that reflected the teamwork, organisational and overall capabilities of the groups. This paper describes the different types of activities developed for the Session 4 and presents an analysis of the perceptions of the students and staff involved. The student response to the Session 4 activities, obtained via questionnaires, was extremely positive, with the majority finding them fun, yet challenging, and ‘worthwhile’. The activities were perceived to enhance subject understanding; develop students’ problem‐solving skills; allow the application of knowledge to new situations, and helped to identify gaps in knowledge to direct further study. Staff found the activities innovative and exciting learning tools for the students. The Session 4 activities described here are useful educational resources that could be adapted for other PBL courses in a wide variety of subject areas.
Paediatric dentistry in outreach settings: an essential part of undergraduate curricula?
Authors: Hunter M. L. , Chaudhry U.
Published: October 2009

Introduction:  Although placements in primary care settings remote from dental schools are becoming a common feature of undergraduate dental curricula, little evidence is available regarding the experience of paediatric dentistry gained in this way.

Materials and methods:  Treatment logs relating to salaried primary care placements undertaken by the Class of 2007 at Cardiff University School of Dentistry were examined, particular attention being paid to paediatric‐specific procedures.

Results:  Forty‐nine logs relating to placements undertaken in South East Wales and 51 relating to those in North Wales were retrieved. In South East Wales, 90% of students gained experience of primary tooth restoration, 61% carrying out primary endodontics. Sixty‐three percent of students undertaking placements in South East Wales and 69% of those placed in North Wales gained experience of primary tooth extraction under local anaesthesia. All but three students gained experience of administering inhalation sedation.

Discussion:  The findings of this study should go some way towards reassuring those who have expressed concern that recruitment difficulties within dental schools inevitably lead to increasing numbers of students qualifying without clinical experience of paediatric dental procedures considered to be within the remit of a newly qualified dental practitioner. However, there remains wide variation in the breadth and depth of experience of individual students and it is still possible for some students to graduate without what might be considered core experience in paediatric dentistry.

Conclusion:  Salaried primary care settings are ideally placed to provide students with experience of paediatric‐specific procedures. Clinical education in paediatric dentistry should, therefore, incorporate the strengths of dental school and placement education.
Implementation of the virtual learning environment into a UK orthodontic training programme: the postgraduate and lecturer perspective
Authors: Shah R. , Cunningham S. J.
Published: October 2009

The virtual learning environment (VLE) was formally introduced into the orthodontic postgraduate teaching programme at the UCL Eastman Dental Institute in October 2006 with the main role to support the existing didactic teaching. The aim of this study was to establish the programme co‐ordinator, lecturer and postgraduate perspective on the introduction of the VLE as an adjunct to other teaching methods. All participants were interviewed utilising open‐ended questions to ascertain their response. The interviews were semi‐structured and were continued until no new information was elicited. The interviews suggested that the programme co‐ordinator, lecturers and the majority of the postgraduates were confident that the VLE could produce a better learning experience. The VLE has a number of advantages and disadvantages, however, there is great potential for the VLE to encourage a constructivist approach to teaching and learning. Moves have been made to align aspects, such as assessment, with the VLE and the rest of the curriculum.
The definition of human viability: a historical perspective
Authors: Pignotti MS
Published: October 2009

Aim: To investigate the current concepts related to the definition of human viability in a historical perspective.

Methods: A review of the international literature was performed by using PubMed, Google, Embase to find definitions of Human Viability. The papers collected were divided chronologically.

Results: Over the years, many authors have debated the concept of the limit of human viability, starting from Ballantyne in the early 1900. The definition differs from author to author.

Conclusion: The definition of human viability is still under discussion. It depends primarily, but not only, on gestational age. A number of genetic, cultural, social and technological variables are also influential. This definition could have an impact on legislation and the widespread misunderstanding of this concept in the lay public could also be enhanced by a frank discussion among clinicians and other professionals.
Gestational diabetes and offspring body disproportion
Authors: Ahlsson F , Lundgren M , Tuvemo T , Gustafsson J , Haglund B
Published: October 2009

Aim:  It has been demonstrated that females born large for gestational age (LGA) in weight but not length are at increased risk of being obese at childbearing age. We addressed the question whether women with gestational diabetes mellitus (GDM) are at increased risk of giving birth to such infants.

Methods:  Birth characteristics of 884 267 infants of non‐diabetic mothers and 7817 of mothers with GDM were analysed. LGA was defined as birth weight or birth length >2 standard deviation scores for gestational age. Multiple logistic regression analysis was performed.

Results:  The odds ratio (OR) for a woman with GDM to give birth to an LGA infant that was heavy alone was four times increased (OR: 3.71, 95% CI: 3.41–4.04). Furthermore, in the population of mothers giving birth to LGA infants, the proportion heavy alone was 68% in the group of women with GDM compared with 64.4% in the group of non‐diabetic women. The risks were independent of gender of the foetus.

Conclusion:  Women with GDM have an almost four times higher risk of delivering an LGA infant that is heavy alone. The noted disproportion between weight and length in infants of such mothers may have an impact on the risk of later obesity.
The capsid protein of human immunodeficiency virus: designing inhibitors of capsid assembly
Authors: Neira José L.
Published: October 2009

The mature capsid of human immunodeficiency virus, HIV‐1, is formed by the assembly of copies of a capsid protein (CA). The C‐terminal domain of CA, CTD, is able to homodimerize and most of the dimerization interface is formed by a single α‐helix from each monomer. Assembly of the HIV‐1 capsid critically depends on CA–CA interactions, including CTD interaction with itself and with the CA N‐terminal domain, NTD. This minireview reports on the search and the design of peptides and small organic compounds that are able to interact with the CTD and/or CA of HIV‐1. Such molecules aim to disrupt and/or alter the oligomerization capability of CTD. The different peptides designed so far interact with CTD mainly via hydrophobic contacts with residues close or belonging to the interface between the dimerization helices. A CTD‐binding organic compound also establishes hydrophobic contacts with regions involved in the interface between the NTD and CTD. These results open new venues for the development of new antiviral drugs that are able to interact with CA and/or its domains, hampering HIV‐1 assembly and infection.
The capsid protein of human immunodeficiency virus: interactions of HIV‐1 capsid with host protein factors
Authors: Mascarenhas Anjali P. , Musier‐Forsyth Karin
Published: October 2009

HIV‐1 is a retrovirus that causes AIDS in humans. The RNA genome of the virus encodes a Gag polyprotein, which is further processed into matrix, capsid and nucleocapsid proteins. These proteins play a significant role at several steps in the viral life cycle. In addition, various stages of assembly, infection and replication of the virus involve necessary interactions with a large number of supplementary proteins/cofactors within the infected host cell. This minireview focuses on the proteomics of the capsid protein, its influence on the packaging of nonviral molecules into HIV‐1 virions and the subsequent role of the molecules themselves. These interactions and their characterization present novel frontiers for the design and advancement of antiviral therapeutics.
α‐Defensins increase lung fibroblast proliferation and collagen synthesis via the β‐catenin signaling pathway
Authors: Han Weihong , Wang Wei , Mohammed Kamal A. , Su Yunchao
Published: October 2009

α‐defensins are released from granules of leukocytes and are implicated in inflammatory and fibrotic lung diseases. In the present study, the effects of α‐defensins on the proliferation and collagen synthesis of lung fibroblasts were examined. We found that α‐defensin‐1 and α‐defensin‐2 induced dose‐dependent increases in the incorporation of 5‐bromo‐2′‐deoxy‐uridine into newly synthesized DNA in two lines of human lung fibroblasts (HFL‐1 and LL‐86), suggesting that α‐defensin‐1 and α‐defensin‐2 stimulate the proliferation of lung fibroblasts. α‐defensin‐1 and α‐defensin‐2 also increased collagen‐I mRNA (COL1A1) levels and protein contents of collagen‐I and active/dephosphorylated β‐catenin without changes in total β‐catenin protein content in lung fibroblasts (HFL‐1 and LL‐86). Inhibition of the β‐catenin signaling pathway using quercetin prevented increases in cell proliferation and the protein content of collagen‐I and active/dephosphorylated β‐catenin in lung fibroblasts, and in COL1A1 mRNA levels and collagen release into culture medium induced by α‐defensin‐1 and α‐defensin‐2. Knocking‐down β‐catenin using small interfering RNA technology also prevented α‐defensin‐induced increases in cell proliferation and the protein content of collagen‐I and active/dephosphorylated β‐catenin in lung fibroblasts, and in COL1A1 mRNA levels. Moreover, increases in the phosphorylation of glycogen synthase kinase 3β, accumulation/activation of β‐catenin, and collagen synthesis induced by α‐defensin‐1 and α‐defensin‐2 were prevented by p38 mitogen‐activated protein kinase inhibitor SB203580 and phosphoinositide 3‐kinase inhibitor LY294002. These results indicate that α‐defensin‐1 and α‐defensin‐2 stimulate proliferation and collagen synthesis of lung fibroblasts. The β‐catenin signaling pathway mediates α‐defensin‐induced increases in cell proliferation and collagen synthesis of lung fibroblasts. α‐defensin‐induced activation of β‐catenin in lung fibroblasts might be caused by phosphorylation/inactivation of glycogen synthase kinase 3β as a result of the activation of the p38 mitogen‐activated protein kinase and phosphoinositide 3‐kinase/Akt pathways.
Predicting recovery of urination control in cats after sacrocaudal injury: a prospective study
Authors: Tatton B. , Jeffery N. , Holmes M.
Published: October 2009

Objectives: To determine whether intact tail base pain sensation predicts control of urination after sacrocaudal fracture‐subluxation in cats.

Methods: Twenty–one cats affected by sacrocaudal fracture‐subluxation were diagnosed routinely by radiography. The ability of each cat to detect a painful stimulus applied to the tail base was tested by application of pressure using a standard surgical instrument. Cats were then hospitalised for up to 30 days and categorised according to whether they showed control of urination. A value of P<0·05 was regarded as significant. The results were analysed to produce data regarding sensitivity, specificity and the positive and negative predictive value of the test.

Results: All 11 cats that had intact tail base sensation showed control of urination within three days. Four of the 10 cats without tail base pain sensation did not recover control of urination by day 30.

Clinical Significance: Intact tail base sensation predicts control of urination and is therefore a useful screening test.
Gastrointestinal foreign bodies in dogs and cats: a retrospective study of 208 cases
Authors: Hayes G.
Published: October 2009

Objectives:To establish predilection sites of obstruction and to investigate clinical factors associated with a poor outcome.

Methods:A retrospective study of 208 consecutive cases over a 48‐month period from first‐opinion practice.

Results:Overall, 91 per cent of cases recovered with higher survival rates from discrete foreign bodies (94 per cent in dogs and 100 per cent in cats) as opposed to linear foreign bodies (80 per cent in dogs and 63 per cent in cats). English bull terriers, springer spaniels, Staffordshire bull terriers, Border collies and Jack Russell terriers were over‐represented. In dogs, 63 per cent of obstructions occurred in the jejunum but foreign objects were encountered at all points along the gastrointestinal tract. A longer duration of clinical signs, the presence of a linear foreign body and multiple intestinal procedures were associated with significantly increased mortality. Neither the degree of obstruction (partial or complete) nor the location of the foreign body was shown to have a significant influence on survival.

ClinicalSignificance:Prompt presentation, diagnosis and surgical intervention improve the outcome of gastrointestinal obstruction by foreign bodies. At surgery, the minimal number of intestinal procedures should be performed to restore the integrity of the alimentary tract.
Outcome following removal of canine spindle cell tumours in first opinion practice: 104 cases
Authors: Chase D. , Bray J. , Ide A. , Polton G.
Published: October 2009

Objectives:To define the outcome of a cohort of canine patients with a histological diagnosis of spindle cell tumour of soft tissue managed solely by surgery in first opinion practice.

Methods:Clinical details of 104 spindle cell sarcomas submitted to Finn Pathologists during the year 2000 were reviewed. Questionnaires were sent to the submitting veterinarians, requesting details about the tumour, surgery performed and ultimate outcome of the patient.

Results:The method of surgical resection was described as marginal in 45 dogs (44·2 per cent). Excision margins of 3 cm or more were described in less than 10 per cent of cases. Tumours recurred locally in 29 dogs (27·9 per cent). Eighteen dogs (21·7 per cent) died of tumour‐related causes. Most deaths were unrelated to sarcoma (50 dogs, 60·2 per cent) or unknown (15 dogs, 18 per cent). The median survival time was 1013 days. Tumour size, location or degree of surgical resection were not significantly related to survival or tumour recurrence. A palpable assessment of tumour invasion into underlying tissues was significantly associated with decreased disease‐free interval (P<0·0001) and survival time (P = 0·0070).

ClinicalSignificance:The results of this retrospective study indicate that many spindle cell tumours managed in first opinion practice exhibit a low‐grade biological behaviour and may respond well to more conservative surgery than current recommendations advise.
Energy, Climate Change, Meat, and Markets: Mapping the Coordinates of the Current World Food Crisis
Authors: Jarosz Lucy
Published: October 2009

The widely used metaphor of a perfect storm identifies the world food crisis as a contingent event that will end when food prices decline. The problem is one of supply and demand. The solution is a technological fix focused upon increasing the productivity of small farmers through a second green revolution and integrating them into markets. An international political economy/ecology approach to the food crisis reveals that the food crisis is a predictable outcome of an oil‐dependent feedgrain–livestock complex supplying a meat‐centric diet for those who can buy it. This complex contributes substantially to climate change and is framed by neoliberal development policies, which deepen the commoditization of food, monetize food security and leave the world’s people vulnerable to periodic food price spikes. The food crisis is linked to energy, climate change, the financial crisis and a socially and environmentally unsustainable grain–livestock complex and must be analyzed and addressed in its relational position to these other crises.
Spaces of Work and Everyday Life: Labour Geographies and the Agency of Unorganised Temporary Migrant Workers
Authors: Rogaly Ben
Published: October 2009

In this study, I focus on the agency of unorganised temporary migrant workers – people who travel away to work for just a few weeks or months. Such workers have been relatively neglected in labour geography. Perhaps surprisingly, given the focus on the agency of capital in much of his writing, I build on two arguments made by David Harvey. First, workers’ spatial mobility is complex and may involve short as well as longer term migrations, and secondly that this can have significance both materially and in relation to the subjective experience of employment. The spatial embeddedness of temporary migrant workers’ everyday lives can be a resource for shaping landscapes (and ordinary histories) of capitalism, even though any changes may be short‐lived and take place at the micro‐scale. The article is illustrated with case study material from research with workers in the agriculture sector in India and the UK, and concludes with more general implications for labour geographers engaged with other sectors and places.
Gene Expression Analysis of Tuberous Sclerosis Complex Cortical Tubers Reveals Increased Expression of Adhesion and Inflammatory Factors
Authors: Boer Karin , Crino Peter B. , Gorter Jan A. , Nellist Mark , Jansen Floor E. , Spliet Wim G.M. , Van Rijen Peter C. , Wittink Floyd R.A. , Breit Timo M. , Troost Dirk , Wadman Wytse J. , Aronica Eleonora
Published: October 2009

Cortical tubers in patients with tuberous sclerosis complex are associated with disabling neurological manifestations, including intractable epilepsy. While these malformations are believed to result from the effects ofTSC1orTSC2gene mutations, the molecular mechanisms leading to tuber formation, as well as the onset of seizures, remain largely unknown. We used the Affymetrix Gene Chip platform to provide the first genome‐wide investigation of gene expression in surgically resected tubers, compared with histological normal perituberal tissue from the same patients or autopsy control tissue. We identified 2501 differentially expressed genes in cortical tubers compared with autopsy controls. Expression of genes associated with cell adhesion, for example,VCAM1,integrinsandCD44, or with the inflammatory response, including complement factors,serpinA3,CCL2and several cytokines, was increased in cortical tubers, whereas genes related to synaptic transmission, for example, the glial glutamate transporterGLT‐1, and voltage‐gated channel activity, exhibited lower expression. Gene expression in perituberal cortex was distinct from autopsy control cortex suggesting that even in the absence of tissue pathology the transcriptome is altered in TSC. Changes in gene expression yield insights into new candidate genes that may contribute to tuber formation or seizure onset, representing new targets for potential therapeutic development.
Diabetic macular oedema and visual loss: relationship to location, severity and duration
Authors: Gardner Thomas W. , Larsen Michael , Girach Aniz , Zhi Xin ,   on behalf of the Protein Kinase C Diabetic Retinopathy Study (PKC‐DRS2) Study Group
Published: October 2009

Purpose:  To assess the relationship between visual acuity (VA) and diabetic macular oedema (DMO) in relation to the location of retinal thickening and the severity and duration of central macular thickening.

Methods:  Data from 584 eyes in 340 placebo‐treated patients in the 3‐years‐long Protein Kinase C Diabetic Retinopathy Study (PKC‐DRS2) trial were used to investigate the relationship between VA and DMO. Eligible eyes had moderately severe to very severe non‐proliferative diabetic retinopathy and VA of at least 45 letters on Early Treatment Diabetic Retinopathy Study (ETDRS) charts (Snellen equivalent = 20/125). Diabetic retinopathy and DMO status were assessed using stereo photographs.

Results:  Nearly one third of study eyes had foveal centre‐involving DMO at the start of the trial. Sustained moderate visual loss was found in 36 eyes, most commonly associated with DMO at the centre of the fovea in 73% of eyes. There was a strong relationship (p < 0.001) between foveal centre involvement with DMO and mean VA. Mean VA decreased with increasing retinal thickness at the centre (p < 0.001) and increasing duration of centre‐involving DMO (p < 0.001).

Conclusion:  This study documents the relationship between duration of DMO and progressive vision loss, and the key role of central foveal involvement in patients with diabetic retinopathy. These data will help to develop future strategies to prevent vision loss.
The microbial methane cycle
Authors: Murrell J. Colin , Jetten Mike S. M.
Published: October 2009

This special issue highlights several recent discoveries in the microbial methane cycle, including the diversity and activity of methanotrophic bacteria in special habitats, distribution and contribution of the newly discovered Verrucomicrobia, metabolism of methane and related one‐carbon compounds such as methanol and methylamine in freshwater and marine environments, methanol and methane‐dependent nitrate reduction, the relationships of methane cycle microorganisms with plants and animals, and the environmental factors that regulate microbial processes of the methane cycle. These articles also highlight the plethora of new organisms and metabolism relating to the methane cycle that have been discovered in recent years and outline the many questions in the methane cycle that still need to be addressed. It is clear that despite a tremendous amount of research on the biology of the methane cycle, the microbes involved in catalysing methane production and consumption harbour many secrets that need to be disclosed in order for us to fully understand how the biogeochemical methane cycle is regulated in the environment, and for us to make future predictions about the global sources and sinks of methane and how anthropogenic changes impact on the cycling of this important greenhouse gas.
A Study in the Process Modeling of the Startup of Fuel Cell/Gas Turbine Hybrid Systems
Authors: Shelton Michael , Celik Ismail , Liese Eric , Tucker David
Published: October 2009

As energy demands increase and the associated costs increase with that demand, newer energy alternatives are becoming more important to society. Although not new, fuel cell technology is taking a lead role in the quest for a cleaner and competitive power generation system. High efficiencies on the order of 50% are now possible with stand-alone fuel cells. When coupled with a gas turbine, efficiencies of around 70% may be expected. However, the fuel cell/gas turbine hybrid has inherent problems of stability and unpredictable response to adverse transients that first must be addressed to make this technology viable. The National Energy Technology Laboratories (NETL) in Morgantown is involved in the development of such hybrid technology. This study details a process modeling approach based on a commercial modeling package, and is associated specifically with the NETL Hybrid Performance (HYPER) research effort. Simulation versus experimental test data are presented to validate the process model during the cold flow startup phase. The results provide insight into the transients of the system built at NETL.
Effect of Film Cooling on Turbine Capacity
Authors: Povey T.
Published: October 2009

This paper describes a method that allows the effect of film cooling on the capacity of a turbine to be computed. The model is based on fundamental cooling performance parameters and is applicable to situations in which a mainstream flow is displaced by a partially mixed film cooling layer. The purpose is to quantify the error that is incurred in the engine situation when common—but simplified—assumptions are made regarding the flow, and where necessary, to provide a means of correcting the capacity for the effect of the film cooling flow.
Dynamic Analysis of Fretting-Wear in Friction Contact Interfaces
Authors: Salles Loïc , Blanc Laurent , Thouverez Fabrice , Gouskov Alexander M.
Published: October 2009

Fretting wear is a very important phenomenon occurring in bladed disks. It causes the blades to be replaced in turbomachines during their life-cycle. Methods exist to predict fretting-wear in quasistatic analysis. However, they do not predict all the phenomena observed in blade attachments on real turbomachines. That is why this study assumes that dynamics plays a role in fretting-wear. This paper is devoted to the realistic modeling and calculation of fretting-wear and dynamical response of structures in unilateral contact with friction. Vibration and wear phenomena present very different scales both in time and space. Therefore the difficulty is in finding methods that enable one to solve the nonlinear problem with a good compromise between the approximations made about the dynamical aspects and those linked with fretting-wear issues. Here, phenomenological examples are studied. They involve a small number of degrees of freedom with a view to understanding the complex coupling between vibration and fretting-wear. This way, they will show the relative importance of parameters.
Controlling Journal Bearing Instability Using Active Magnetic Bearings
Authors: El-Shafei A. , Dimitri A. S.
Published: October 2009

Journal bearings (JBs) are excellent bearings due to their large load carrying capacity and favorable damping characteristics. However, journal bearings are known to be prone to instabilities. The oil whirl and oil whip instabilities limit the rotor maximum rotating speed. In this paper, a novel approach is used to control the journal bearing instability. An active magnetic bearing (AMB) is used to overcome the JB instability and to increase its range of operation. The concept is quite simple: Rather than using the AMB as a load carrying element, the AMB is used as a controller only, resulting in a much smaller and more efficient AMB. The load carrying is done by the journal bearings, exploiting their excellent load carrying capabilities, and the JB instability is overcome with the AMB. This results in a combined AMB/JB that exploits the advantages of each device and eliminates the deficiencies of each bearing. Different controllers for the AMB to control the JB instability are examined and compared theoretically and numerically. The possibility of collocating the JB and the AMB is also examined. The results illustrate the effectiveness of the concept.
Second Law Efficiency of the Rankine Bottoming Cycle of a Combined Cycle Power Plant
Authors: Gülen S. Can , Smith Raub W.
Published: October 2009

A significant portion of the new electrical generating capacity installed in the past decade has employed heavy-duty gas turbines operating in a combined cycle configuration with a steam turbine bottoming cycle. In these power plants approximately one-third of the power is generated by the bottoming cycle. To ensure that the highest possible combined cycle efficiency is realized it is important to develop the combined cycle power plant as a system. Doing so requires a solid understanding of the efficiency entitlement of both, topping and bottoming, cycles separately and as a whole. This paper describes a simple but accurate method to estimate the Rankine bottoming cycle power output directly from the gas turbine exhaust exergy, utilizing the second law of thermodynamics. The classical first law approach, i.e., the heat and mass balance method, requires lengthy calculations and complex computer-based modeling tools to evaluate Rankine bottoming cycle performance. In this paper, a rigorous application of the fundamental thermodynamic principles embodied by the second law to the major cycle components clearly demonstrates that the Rankine cycle performance can be accurately represented by several key parameters. The power of the second law approach lies in its ability to highlight the theoretical entitlement and state-of-the-art design performances simultaneously via simple fundamental relationships. By considering economically and technologically feasible upper limits for the key parameters, the maximum achievable bottoming cycle power output is readily calculable for any given gas turbine from its exhaust exergy.
Low Temperature Combustion Using Nitrogen Enrichment to Mitigate NOx From Large Bore Natural Gas Fueled Engines
Authors: Biruduganti Munidhar S. , Gupta Sreenath B. , Sekar Raj
Published: October 2009

Low temperature combustion is identified as one of the pathways to meet the mandatory ultra low NOx emissions levels set by the regulatory agencies. Exhaust gas recirculation (EGR) is a well known technique to realize low NOx emissions. However, EGR has many built-in adverse ramifications that negate its advantages in the long term. This paper discusses nitrogen enrichment of intake air using air separation membranes as a better alternative to the mature EGR technique. This investigation was undertaken to determine the maximum acceptable level of nitrogen enrichment of air for a single-cylinder spark-ignited natural gas engine. NOx reduction as high as 70% was realized with a modest 2% nitrogen enrichment while maintaining power density and simultaneously improving fuel conversion efficiency (FCE). Any enrichment beyond this level degraded engine performance in terms of power density, FCE, and unburned hydrocarbon emissions. The effect of ignition timing was also studied with and without N2 enrichment. Finally, lean burn versus stoichiometric operation utilizing nitrogen enrichment was compared. Analysis showed that lean burn operation along with nitrogen enrichment is one of the effective pathways for realizing better FCE and lower NOx emissions.
Condenser Tube Examination Using Acoustic Pulse Reflectometry
Authors: Amir N. , Barzelay O. , Yefet A. , Pechter T.
Published: October 2009

Acoustic pulse reflectometry (APR) has been applied extensively to tubular systems in research laboratories for purposes of measuring input impedance, bore reconstruction, and fault detection. Industrial applications have been mentioned in the literature, though they have not been widely implemented. Academic APR systems are extremely bulky, often employing source tubes of 6 m in length, which limits their industrial use severely. Furthermore, leak detection methods described in the literature are based on indirect methods, by carrying out bore reconstruction and finding discrepancies between the expected and reconstructed bore. In this paper we describe an APR system designed specifically for detecting faults commonly found in industrial tube systems: leaks, increases in internal diameter caused by wall thinning, and constrictions. The system employs extremely short source tubes, in the order of 20 cm, making it extremely portable, but creating a large degree of overlap between forward and backward propagating waves in the system. A series of algorithmic innovations enable the system to perform the wave separation mathematically, and then identify the above faults automatically with a measurement time on the order of 10 s per tube. We present several case studies of condenser tube inspection, showing how different faults are identified and reported.
Creep Effects on Design Below the Temperature Limits of ASME Section III Subsection NB
Authors: Sham T.-L. , Jetter Robert I. , Eno Daniel R.
Published: October 2009

Some recent studies of material response have identified an issue that crosses over and blurs the boundary between ASME Boiler and Pressure Vessel Code Section III Subsection NB and Subsection NH. For very long design lives, the effects of creep show up at lower and lower temperature as the design life increases. Although true for the temperature at which the allowable stress is governed by creep properties, the effect is more apparent, e.g., creep effects show up sooner, at local structural discontinuities and peak thermal stress locations. This is because creep is a function of time, temperature, and stress, and the higher the localized stress, the lower in temperature creep begins to cause damage. If the threshold is below the Subsection NB to NH temperature boundary, 700°F for ferritic steels and 800°F for austenitic materials, then this potential failure mode will not be considered. Unfortunately, there is no experience base with very long lives at temperatures close to but under the Subsection NB to NH boundary to draw on. This issue is of particular interest in the application of Subsection NB rules of construction to some high temperature gas-cooled reactor concepts. The purpose of this paper is, thus, twofold: one part is about statistical treatment and extrapolation of sparse data for a specific material of interest, SA-533 Grade B Class 1; the other part is about how these results could impact current design procedures in Subsection NB.
Development of Local Heat Transfer Models for Safety Assessment of High Temperature Gas-Cooled Reactor Cores—Part I: Pebble Bed Reactors
Authors: Stainsby Richard , Worsley Matthew , Grief Andrew , Dawson Frances , Davies Mike , Coddington Paul , Baker Jo , Dennier Ana
Published: October 2009

This and the subsequent paper present models developed for determining fuel particle and fuel element temperatures in normal operation and transient conditions in high temperature reactor cores. Multiscale modeling concepts are used to develop the models for both pebble bed and prismatic core types. This paper, Part I, presents the development of the model for pebble bed reactors. Comparison is made with finite element simulations of an idealized “two-dimensional” pebble in transient conditions, and with a steady-state analytical solution in a spherical pebble geometry. A method is presented for determining the fuel temperatures in the individual batches of a multibatch recycle refuelling regime. Implementation of the multiscale and multibatch fuel models in a whole-core computational fluid dynamics model is discussed together with the future intentions of the research program.
Biodiesel as an Alternative Fuel in Siemens Dry Low Emissions Combustors: Atmospheric and High Pressure Rig Testing
Authors: Liu Kexin , Wood John P. , Buchanan Eoghan R. , Martin Pete , Sanderson Victoria E.
Published: October 2009

Atmospheric and high pressure rig tests were conducted to investigate the feasibility of using biodiesel as an alternative fuel to power industrial gas turbines in one of the world’s leading dry low emissions (DLE) combustion systems, the SGT-100. At the same conditions, tests were also carried out for mineral diesel to provide reference information to evaluate biodiesel as an alternative fuel. In atmospheric pressure rig tests, the likelihood of the machine lighting was identified based on the measured probability of the ignition of a single combustor. Lean ignition and extinction limits at various air temperatures were also investigated with different air assist pressures. The ignition test results reveal that reliable ignition can be achieved with biodiesel across a range of air mass flow rates and air fuel ratios (AFRs). In high pressure rig tests, emissions and combustion dynamics were measured for various combustor air inlet pressures, temperatures, combustor wall pressure drops, and flame temperatures. These high pressure rig results show that biodiesel produced less NOx than mineral diesel. The test results indicate that the Siemens DLE combustion system can be adapted to use biodiesel as an alternative fuel without major modification.
Comment on “The
Arabidopsis
Circadian Clock Incorporates a cADPR-Based Feedback Loop”
Authors: Xu Xiaodong , Graeff Richard , Xie Qiguang , Gamble Karen L. , Mori Tetsuya , Johnson Carl Hirschie
Published: October 2009

Dodd
et al
. (Reports, 14 December 2007, p. 1789) reported that the
Arabidopsis
circadian clock incorporates the signaling molecule cyclic adenosine diphosphate ribose (cADPR). In contrast, we found that there is no rhythm of cADPR levels nor are there any significant effects on the rhythm by cADPR overexpression, thus raising questions about the conclusions of Dodd
et al
.
Reactome Array: Forging a Link Between Metabolome and Genome
Authors: Beloqui Ana , Guazzaroni María-Eugenia , Pazos Florencio , Vieites José M. , Godoy Marta , Golyshina Olga V. , Chernikova Tatyana N. , Waliczek Agnes , Silva-Rocha Rafael , Al-ramahi Yamal , La Cono Violetta , Mendez Carmen , Salas José A. , Solano Roberto , Yakimov Michail M. , Timmis Kenneth N. , Golyshin Peter N. , Ferrer Manuel
Published: October 2009

Metabolite Arrays

Methods suitable for the biochemical analysis of multiple metabolic pathways in mixed samples are in short supply.

Beloqui
et al.

(p.
252
) report a method to sample the global metabolic state of an organism or mixture of organisms using an array of more than 1500 metabolites linked to a glass slide. The substrates are linked to the plate so that the reaction of an enzyme with one of the metabolites releases a fluorescent dye, which allows sensitive detection of the enzymatic activity. From a sample with small numbers of a mixture of bacteria, the authors were able to collect DNA, amplify it in a host bacterium, and measure its encoded metabolic activity with the array. Furthermore, by coating the substrates on nanoparticles with a specially designed linker, the authors could trap and purify enzymes that reacted with the immobilized substrate. The metabolite array may be useful in the characterization of environmental samples, in diagnostic procedures, and in enzyme discovery.
KLF Family Members Regulate Intrinsic Axon Regeneration Ability
Authors: Moore Darcie L. , Blackmore Murray G. , Hu Ying , Kaestner Klaus H. , Bixby John L. , Lemmon Vance P. , Goldberg Jeffrey L.
Published: October 2009

Containing Neuronal Exuberance

In rats and mice, around the time of birth, neurons of the central nervous system switch from a growth mode and lose their ability to regenerate. Studying retinal ganglion cells of the rat,

Moore
et al.

(p.
298
; see the Perspective by

Subang and Richardson

) identified a gene,
Krüppel-like factor-4
(
KLF4
), that seems to contribute to the switch. The
KLF4
gene belongs to a family of related transcription factors that possess repressive or enhancing effects on axon growth. The combinatorial effect of this family of transcription factors before and after birth may fine-tune the ability of the neurons to extend axons.
Sex, War (and Ecology)
Sex and War
How Biology Explains Warfare and Terrorism and Offers a Path to a Safer World

by Malcolm Potts and Thomas Hayden

BenBella, Dallas, 2008. 463 pp. $24.95, C$29. ISBN 9781933771571.
Authors: Kaplan Hillard
Published: October 2009

Potts and Hayden argue that human aggression is primarily a male behavior rooted in the evolutionary advantages violence once provided but that empowering women can help overcome the biology of war.
Mapping Excited-State Dynamics by Coherent Control of a Dendrimer’s Photoemission Efficiency
Authors: Kuroda Daniel G. , Singh C. P. , Peng Zhonghua , Kleiman Valeria D.
Published: October 2009

Phasing-In Emission

In keeping with quantum mechanics, the dynamics that ensue when molecules absorb light depend not only on the light's frequency but also its phase, which can manipulate excited state trajectories through interference. Recently, an impressive degree of control has been achieved over complex light absorbers, including proteins, by iteratively adapting the phase of a laser excitation pulse. However, the optimal pulses used are often too complicated to reveal straightforward insights into the systems being manipulated.

Kuroda
et al.

(p.
263
; see the Perspective by

Batista

) applied iterative phase manipulation toward optimizing the photoemission efficiency of a macromolecular donor-acceptor system, followed by statistical analysis to isolate a fairly simple phase function underlying much of the control mechanism. Careful follow-up experiments revealed an intuitive picture of the excited state behavior.
Ice Age Terminations
Authors: Cheng Hai , Edwards R. Lawrence , Broecker Wallace S. , Denton George H. , Kong Xinggong , Wang Yongjin , Zhang Rong , Wang Xianfeng
Published: October 2009

Monsoon Cave Recordings

Rocky deposits in caves in central China record the changes over time in the Asian Monsoon through the oxygen isotopic composition of the minerals from which they are formed. These deposits can be precisely dated and provide an absolute time line for climate system changes.

Cheng
et al.

(p.
248
; see the Perspective by

Severinghaus

) present oxygen isotope data from speleothems collected from Sanbao Cave, China, for the three glacial terminations that occurred between 120,000 and 350,000 years ago. The data reveal variations in the amount of precipitation delivered by the Asian Monsoon over time. Comparison of the timing of these changes with corresponding changes in ice core and marine sedimentary records provides mechanistic insights into how variations in insolation affect ice sheets and ice age terminations.
Two Doors and a Goat
The Monty Hall Problem
The Remarkable Story of Math's Most Contentious Brain Teaser

by Jason Rosenhouse

Oxford University Press, Oxford, 2009. 208 pp. $24.95, £13.99. ISBN 9780195367898.
Authors: Granberg Donald O.
Published: October 2009

Rosenhouse presents a perspective on probability focused on the Monty Hall problem and the controversies surrounding it.