The problems of urinary tract infections with Candida spp. aetiology in women.

Science.gov (United States)

Tomczak, Hanna; Szałek, Edyta; Grześkowiak, Edmund

2014-08-29

Urinary tract infections (UTIs) in women are a growing clinical concern. The most frequent risk factors of UTIs with fungal aetiology in women are: antibiotic therapy (especially broad-spectrum antibiotics), immunosuppressive therapy, diabetes, malnutrition, pregnancy, and frequent intercourse. The aim of the study was to analyse urinary tract infections with Candida spp. aetiology in women hospitalised at the Clinical Hospital in Poznań, Poland, between 2009 and 2011. The investigations revealed that as many as 71% of positive urine cultures with Candida fungi came from women. The following fungi were most frequently isolated from the patients under analysis: C. albicans (47%), C. glabrata (31%), C. tropicalis (6%), C. krusei (3%). In order to diagnose a UTI the diagnosis cannot be based on a single result of a urine culture. Due to the small number of antifungal drugs and high costs of treatment, antifungal drugs should be applied with due consideration and care.

Short article: Presence, extent and location of pancreatic necrosis are independent of aetiology in acute pancreatitis.

Science.gov (United States)

Verdonk, Robert C; Sternby, Hanna; Dimova, Alexandra; Ignatavicius, Povilas; Koiva, Peter; Penttila, Anne K; Ilzarbe, Lucas; Regner, Sara; Rosendahl, Jonas; Bollen, Thomas L

2018-03-01

The most common aetiologies of acute pancreatitis (AP) are gallstones, alcohol and idiopathic. The impact of the aetiology of AP on the extent and morphology of pancreatic and extrapancreatic necrosis (EXPN) has not been clearly established. The aim of the present study was to assess the influence of aetiology on the presence and location of pancreatic necrosis in patients with AP. We carried out a post-hoc analysis of a previously established multicentre cohort of patients with AP in whom a computed tomography was available for review. Clinical data were obtained from the medical records. All computed tomographies were revised by the same expert radiologist. The impact of aetiology on pancreatic and EXPN was calculated. In total, 159 patients with necrotizing pancreatitis were identified from a cohort of 285 patients. The most frequent aetiologies were biliary (105 patients, 37%), followed by alcohol (102 patients, 36%) and other aetiologies including idiopathic (78 patients, 27%). No relationship was found between the aetiology and the presence of pancreatic necrosis, EXPN, location of pancreatic necrosis or presence of collections. We found no association between the aetiology of AP and the presence, extent and anatomical location of pancreatic necrosis.

NON-TRAUMATIC COMA- INCIDENCE, AETIOLOGY AND OUTCOME

Directory of Open Access Journals (Sweden)

Mallikarjun R. Patil

2017-10-01

Full Text Available BACKGROUND Acute non-traumatic coma is one of the most common paediatric emergencies, which arouses much anxiety and apprehension in both parents and physicians. Due to heterogeneity of causes in these patients, prediction of outcome is difficult and unfortunately no single clinical, laboratory or electrophysiological parameters singly predict their outcome. Aetiology of nontraumatic coma varies depending on different geographical area. We have attempted to find the incidence, aetiology and outcome and delineate neurological signs to predict the prognosis in this study. The aim of this study is to study the incidence, aetiology and outcome of non-traumatic coma in children. MATERIALS AND METHODS 100 consecutive cases of non-traumatic coma between 5months and 15 years of age were selected for the study. Clinical signs and findings were recorded at admission (‘0’ Hr and after ‘48’ Hrs. of hospital stay. Aetiology of coma is determined on the basis of clinical history, examination and relevant laboratory investigations by the treating physician. These children were followed up till the death in the hospital or discharged from the hospital. Discharged patients were asked for followup after 4 weeks. During this period, all of them were evaluated by formal neurological examination and for special sensory involvement. The neurological outcomes were categorised into 6 groups (I-VI based on the severity of neurological involvement. Chisquare test was applied to determine the predictors of outcome. RESULTS 1. The incidence of non-traumatic coma in our hospital based study was 8.02% of all paediatric admissions and 21.64% of all PICU admissions. 2. CNS infections contributed the majority (58% of cases. (Dengue encephalitis-28%, viral encephalitis-12%, TB meningitis-8%, pyogenic meningitis- 6%, Shigella encephalopathy-3% and cerebral malaria-1%. 3. Other non-infectious aetiologies were toxic and metabolic group- 21%, post status epilepticus- 9

Prevalence and Aetiology of Congenitally Deafblind People in Denmark

DEFF Research Database (Denmark)

Dammeyer, Jesper Herup

2010-01-01

A study of prevalence and aetiology was performed on 63 children and 127 adults in Denmark with congenital deafblindness. Using a Scandinavian definition of deafblindness, the prevalence of congenital deafblindness was found to be 1:29,000. Thirty-five different aetiological causes of deafblindness...... were found. Causes of congenital deafblindness were different among adults compared to causes among children. Rubella syndrome (28%, n = 36) and Down syndrome (8%, n = 10) were the largest groups among people above 18 years of age. Among children CHARGE syndrome (16%, n = 13) was the largest group...

Shared Genetic Aetiology between Cognitive Ability and Cardiovascular Disease Risk Factors: Generation Scotland's Scottish Family Health Study

Science.gov (United States)

Luciano, Michelle; Batty, G. David; McGilchrist, Mark; Linksted, Pamela; Fitzpatrick, Bridie; Jackson, Cathy; Pattie, Alison; Dominiczak, Anna F.; Morris, Andrew D.; Smith, Blair H.; Porteous, David; Deary, Ian J.

2010-01-01

People with higher general cognitive ability in early life have more favourable levels of cardiovascular disease (CVD) risk factors in adulthood and CVD itself. The mechanism of these associations is not known. Here we examine whether general cognitive ability and CVD risk factors share genetic and/or environmental aetiology. In this large,…

Viral aetiology influenza like illnesses in Santa Cruz, Bolivia (2010-2012).

Science.gov (United States)

Delangue, Julie; Roca Sanchez, Yelin; Piorkowski, Géraldine; Bessaud, Maël; Baronti, Cécile; Thirion-Perrier, Laurence; Mafayle, Roxana Loayza; Ardaya, Cinthia Avila; Aguilera, Gabriela Añez; Guzman, Jimmy Revollo; Riera, Javier Lora; de Lamballerie, Xavier

2014-02-24

Acute respiratory infections represent a serious public health issue worldwide but virological aetiologies of Influenza Like Illnesses (ILIs) remain largely unknown in developing countries. This study represents the first attempt to characterise viral aetiologies of ILIs in Bolivia. It was performed in Santa Cruz city from January 2010 to September 2012, based on 564 naso-pharyngeal swabs collected in a National Reference Laboratory and real-time PCR techniques, viral cultures and phylogenetic analyses. 50.2% of samples were positive for at least one virus with influenza viruses (Flu A: ~15%; Flu B: ~9%), rhinoviruses (~8%), coronaviruses (~5%) and hRSV (~4%) being the most frequently identified. The pattern of viral infections varied according to age groups. The elucidation rate was the highest (>60%) amongst patients under 10 yo and the lowest (Bolivia in the study period, originating from Central and North America, Europe, Asia and Australia. Our results emphasise the requirement for a reinforced epidemiological and genetic follow-up of influenza and other ILIs in Bolivia to further inform the preparation of vaccines used in the region, guide vaccination campaigns and improve the medical management of patients.

Dynamic bowel obstruction: aetiology, clinical presentation ...

African Journals Online (AJOL)

2005). This makes it essential that studies are made periodically in every region to define the local causes with the idea to do work on their prevention (Adhikari et al., 2010). This study was conducted to describe in our region, the aetiology, clinical presentation, management and outcome of dynamic bowel obstruction.

Mechanism of human tooth eruption

DEFF Research Database (Denmark)

Kjær, Inger

2014-01-01

Human eruption is a unique developmental process in the organism. The aetiology or the mechanism behind eruption has never been fully understood and the scientific literature in the field is extremely sparse. Human and animal tissues provide different possibilities for eruption analyses, briefly ...... keeps this new theory in mind. Understanding the aetiology of the eruption process is necessary for treating deviant eruption courses....... to insight into the aetiology behind eruption. A new theory on the eruption mechanism is presented. Accordingly, the mechanism of eruption depends on the correlation between space in the eruption course, created by the crown follicle, eruption pressure triggered by innervation in the apical root membrane......, and the ability of the periodontal ligament to adapt to eruptive movements. Animal studies and studies on normal and pathological eruption in humans can support and explain different aspects in the new theory. The eruption mechanism still needs elucidation and the paper recommends that future research on eruption...

Molecular diagnosis of microbial aetiologies using SepsiTest™ in the daily routine of a diagnostic laboratory.

Science.gov (United States)

Haag, Heike; Locher, Franziska; Nolte, Oliver

2013-08-01

A universal PCR and sequencing test, SepsiTest™ (Molzym, Germany) was evaluated for its applicability during daily diagnostic routine in a privately operated laboratory. In total, 96 specimens originating from 66 patients under suspect of infectious endocarditis, infections of joints, encephalitis/meningitis, systemic infections and infections of unknown genesis were PCR analysed and compared to culture results. Samples comprised cultured and non-cultured blood, synovial fluid, synovial tissue, heart valves, pacemakers, spinal tissue, cerebrospinal fluid, and swabs. PCR and culture were concordant in 26 negative and 8 positive cases (51.5%). A group of 25 patients was culture-negative but PCR-positive (37.9%). In at least 14 of these, common and/or rare aetiologies were identified, while for 4 patients the results of 16S PCR could not be unequivocally linked with the underlying disease. Benefits and limitations of the molecular test are discussed with special emphasis on technical and economic issues. In conclusion, SepsiTest™ proved to be a valuable tool for the diagnosis of aetiologies, particularly in cases of culture-negative patients who are under strong suspicion for an infection. Copyright © 2013 Elsevier Inc. All rights reserved.

Dynamic bowel obstruction: aetiology, clinical presentation ...

African Journals Online (AJOL)

This study was conducted to describe in our region, the aetiology, clinical presentation, management and outcome of dynamic bowel obstruction. Data were analyzed using SPSS software system. A total of 342 patients were studied. Males outnumbered females by a ratio of 2.1: 1. The median age of patients at presentation ...

Aetiologies of non-malaria febrile episodes in children under 5 years in sub-Saharan Africa.

Science.gov (United States)

Kiemde, Francois; Spijker, René; Mens, Petra F; Tinto, Halidou; Boele, Michael; Schallig, Henk D F H

2016-08-01

To provide an overview of the most frequent aetiologies found in febrile episodes of children under 5 years from sub-Saharan Africa. MEDLINE and EMBASE were searched for publications in English and French on non-malaria fever episodes in African children under 5 years of age, which were published between January 1990 and July 2015. Case reports and conference abstracts were excluded. In total, 3851 titles and abstracts were reviewed, and 153 were selected for full screening of which 18 were included in the present review. Bloodstream infection (BSI) was most commonly investigated (nine of 18) followed by urinary tract infection (UTI) (four of 18) and respiratory tract infection (RTI) (two of 18). Few studies investigated BSI and UTI in the same children (two of 18), or BSI and gastrointestinal infection (GII) (one of 18). As for BSI, the most frequently isolated bacteria were E. coli (four of 12), Streptococcus pneumonia (four of 12), Salmonella spp (three of 12) and Staphylococcus aureus (two of 12) with a positive identification rate of 19.7-33.3%, 5.2-27.6%, 11.7-65.4% and 23.5-42.0%, respectively. As for UTI, the main bacteria isolated were E. coli (six of six) and Klebsiella spp (six of six) with a positive rate of 20.0-72.3% and 10.0-28.5%, respectively. No bacterium was isolated in RTI group, but Human influenzae A and B were frequently found, with the highest positive identification rate in Tanzania (75.3%). Dengue virus (two of 12) was the most frequently reported viral infection with a positive identification rate of 16.7-30.8%. Finally, only rotavirus/adenovirus (69.2% positive identification rate) was found in GII and no bacterium was isolated in this group. The high prevalence of treatable causes of non-malaria fever episodes requires a proper diagnosis of the origin of fever followed by an appropriate treatment, thereby reducing the under-5 mortality in sub-Saharan Africa and preventing the overprescription of antibiotics and thus circumventing the

Myelitis: Differences between multiple sclerosis and other aetiologies.

Science.gov (United States)

Presas-Rodríguez, S; Grau-López, L; Hervás-García, J V; Massuet-Vilamajó, A; Ramo-Tello, C

2016-03-01

Myelitis can appear as an initial symptom in the context of demyelinating diseases, systemic inflammatory diseases, and infectious diseases. We aim to analyse the differences between myelitis associated with multiple sclerosis (MS) and myelitis resulting from other aetiologies. Single-centre, retrospective analysis of patients with initial myelitis (2000-2013). Demographic, aetiological, clinical, radiological and prognostic variables were analysed and compared between patients with myelitis from MS and those with myelitis due to other aetiologies. We included 91 patients; mean follow-up was 7 years. Diagnoses were as follows: MS 57 (63%), idiopathic transverse myelitis 22 (24%), associated systemic diseases 6 (7%), and other diagnoses (6%). Myelitis due to MS was associated with younger age of onset (35 ± 11 vs. 41 ± 13; P = .02), more pronounced sphincter involvement (40.4 vs. 27.3%; P=.05), greater multifocal involvement in spinal MRI (77.2 vs. 26.5%; P=.001), shorter lesion extension (2.4 vs. 1.4 vertebral segments; P=.001), cervical location (82.5 vs. 64.7%; P=.05) and posterior location (89.5 vs. 41.2%; P=.001). Myelitis due to other aetiologies more frequently showed anterior location (47.1 vs. 24.6%; P=.02), and central cord involvement (47.1 vs. 14.1%; P=.001), with better recovery at one year of follow up (EDSS 2.0 vs. 1.5; P=.01). Multivariate analysis showed that multifocal spinal cord involvement (OR 9.38, 95% CI: 2.04-43.1) and posterior cord involvement (OR 2.16, 95% CI: 2.04-2.67) were independently associated with the diagnosis of MS. A high percentage of patients with an initial myelitis event will be diagnosed with MS. The presence of multifocal and posterior spinal cord lesions was significantly associated with the diagnosis of MS. Copyright © 2015 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

Adult bacterial meningitis: aetiology, penicillin susceptibility, risk factors, prognostic factors and guidelines for empirical antibiotic treatment.

Science.gov (United States)

Meyer, C N; Samuelsson, I S; Galle, M; Bangsborg, J M

2004-08-01

Episodes of adult bacterial meningitis (ABM) at a Danish hospital in 1991-2000 were identified from the databases of the Department of Clinical Microbiology, and compared with data from the Danish National Patient Register and the Danish National Notification System. Reduced penicillin susceptibility occurred in 21 (23%) of 92 cases of known aetiology, compared to an estimated 6% in nationally notified cases (p ABM cases in the study population, and in 99.6% of nationally notified cases. The notification rate was 75% for penicillin-susceptible episodes, and 24% for penicillin-non-susceptible episodes (p ABM cases with no identified risk factors, nine of 11 cases with penicillin-non-susceptible bacteria were community-acquired. Severe sequelae correlated independently with age, penicillin non-susceptibility, mechanical ventilation and non-transferral to a tertiary hospital (p ABM should not be based exclusively on clinical notification systems with possible unbalanced under-reporting.

Viral aetiology influenza like illnesses in Santa Cruz, Bolivia (2010–2012)

Science.gov (United States)

2014-01-01

Background Acute respiratory infections represent a serious public health issue worldwide but virological aetiologies of Influenza Like Illnesses (ILIs) remain largely unknown in developing countries. This study represents the first attempt to characterise viral aetiologies of ILIs in Bolivia. Methods It was performed in Santa Cruz city from January 2010 to September 2012, based on 564 naso-pharyngeal swabs collected in a National Reference Laboratory and real-time PCR techniques, viral cultures and phylogenetic analyses. Results 50.2% of samples were positive for at least one virus with influenza viruses (Flu A: ~15%; Flu B: ~9%), rhinoviruses (~8%), coronaviruses (~5%) and hRSV (~4%) being the most frequently identified. The pattern of viral infections varied according to age groups. The elucidation rate was the highest (>60%) amongst patients under 10 yo and the lowest (Bolivia in the study period, originating from Central and North America, Europe, Asia and Australia. Conclusion Our results emphasise the requirement for a reinforced epidemiological and genetic follow-up of influenza and other ILIs in Bolivia to further inform the preparation of vaccines used in the region, guide vaccination campaigns and improve the medical management of patients. PMID:24564892

System viability of organizations and the aetiology of organizational crisis : A Quantitative Assessment of Stafford Beer's Viable System Model

NARCIS (Netherlands)

Pfiffner, M.D.

2017-01-01

Subject of this dissertation is the aetiology of crisis processes which place organizations under existential threats and which often cause organizational demise and bankruptcy. To date, research on organizational crises (OC) has not succeeded in identifying the generic grounds for these detrimental

Shifting white pox aetiologies affecting Acropora palmata in the Florida Keys, 1994-2014.

Science.gov (United States)

Sutherland, Kathryn P; Berry, Brett; Park, Andrew; Kemp, Dustin W; Kemp, Keri M; Lipp, Erin K; Porter, James W

2016-03-05

We propose 'the moving target hypothesis' to describe the aetiology of a contemporary coral disease that differs from that of its historical disease state. Hitting the target with coral disease aetiology is a complex pursuit that requires understanding of host and environment, and may lack a single pathogen solution. White pox disease (WPX) affects the Caribbean coral Acropora palmata. Acroporid serratiosis is a form of WPX for which the bacterial pathogen (Serratia marcescens) has been established. We used long-term (1994-2014) photographic monitoring to evaluate historical and contemporary epizootiology and aetiology of WPX affecting A. palmata at eight reefs in the Florida Keys. Ranges of WPX prevalence over time (0-71.4%) were comparable for the duration of the 20-year study. Whole colony mortality and disease severity were high in historical (1994-2004), and low in contemporary (2008-2014), outbreaks of WPX. Acroporid serratiosis was diagnosed for some historical (1999, 2003) and contemporary (2012, 2013) outbreaks, but this form of WPX was not confirmed for all WPX cases. Our results serve as a context for considering aetiology as a moving target for WPX and other coral diseases for which pathogens are established and/or candidate pathogens are identified. Coral aetiology investigations completed to date suggest that changes in pathogen, host and/or environment alter the disease state and complicate diagnosis. © 2016 The Author(s).

Can mechanical ventilation strategies reduce chronic lung disease?

Science.gov (United States)

Donn, Steven M; Sinha, Sunil K

2003-12-01

Chronic lung disease (CLD) continues to be a significant complication in newborn infants undergoing mechanical ventilation for respiratory failure. Although the aetiology of CLD is multifactorial, specific factors related to mechanical ventilation, including barotrauma, volutrauma and atelectrauma, have been implicated as important aetiologic mechanisms. This article discusses the ways in which these factors might be manipulated by various mechanical ventilatory strategies to reduce ventilator-induced lung injury. These include continuous positive airway pressure, permissive hypercapnia, patient-triggered ventilation, volume-targeted ventilation, proportional assist ventilation, high-frequency ventilation and real-time monitoring.

Aetiology of community-acquired neonatal sepsis in low- and middle-income countries

Directory of Open Access Journals (Sweden)

Donald Waters

2011-12-01

Full Text Available 99% of the approximate 1 million annual neonatal deaths from life-threatening invasive bacterial infections occur in developing countries, at least 50% of which are from home births or community settings. Data concerning aetiology of sepsis in these settings are necessary to inform targeted therapy and devise management guidelines. This review describes and analyses the bacterial aetiology of community-acquired neonatal sepsis in developing countries.

Aetiology of auditory dysfunction in amusia: a systematic review.

Science.gov (United States)

Casey, Daniel Aj

2013-04-24

Amusia, a music-specific agnosia, is a disorder of pitch interval analysis and pitch direction change recognition which results in a deficit in musical ability. The full range of aetiological factors which cause this condition is unknown, as is each cause's frequency. The objective of this study was to identify all causes of amusia, and to measure each of their frequencies. systematic review was conducted by search of multiple databases for articles related to the aetiology of amusic auditory dysfunction. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for reporting of systematic reviews were followed, utilizing the PRISMA checklist and PRISMA flowchart methodology. Retrospective medical database review. evidence yielded from the systematic review process. The initial search protocol identified 5723 articles. Application of a classification review filter and exclusion of irrelevant or duplicates led to the initial identification of 56 relevant studies which detailed 301 patients. However, these studies were of poor quality. Because of this, synthesis and statistical analysis were not appropriate. Although initially a large number of relevant studies were identified, and might point in future to potential diagnostic categories, it was not appropriate to synthesise and analyse them due to poor quality, considerable heterogeneity and small numbers. This suggests that large, high quality studies focussed directly on understanding the aetiology of amusia are required.

Intestinal volvulus: aetiology, morbidity and mortality in Tunisian children.

Science.gov (United States)

Faouzi, Nouira; Yosra, Ben Ahmed; Said, Jlidi; Soufiane, Ghorbel; Aouatef, Charieg; Rachid, Khemakhem; Beji, Chaouachi

2011-01-01

Intestinal volvulus (IV) can occur at various sites of the gastrointestinal tract. In Europe, IV in children is most frequently due to malrotation but in Asia Ascaris infestation is a common cause. This report reviews the experience with IV in children in Tunisia; analyzes the aetiologies as well as the clinical presentations and the benefits of the Ladd's procedure in the treatment of the IV. The authors retrospectively reviewed the case records of all children with IV from January 2000 to December 2009 at the Tunis Children's Hospital. There were 22 boys and nine girls with an age range of one day to four years. Twenty-five (80%) patients presented during the neonatal period. The most common presentation was bilious vomiting and dehydration. The aetiology was identified in all patients: Anomalies in rotation (n=22), omphalo-mesenteric duct (n=3), internal hernia (n=3), cystic lymphangioma (n=2), caocal volvulus (n=1). The bowel resection rate for gangrene was 16%. All patients with malrotation had Ladd's procedure performed. Five patients (19%) developed wound infections. One patient presented with adhesive small bowel obstruction. There were no recurrences following Ladd's procedure for malrotation. Two neonates (6%) died from overwhelming infections. Intestinal volvulus in our environment differs in aetiology from other reports. The resection rates are not similar, however. Early diagnosis reduced the high morbidity and mortality in our study.

SHORT RESEARCH REPORTS The Aetiology and Agents of Pre ...

African Journals Online (AJOL)

Aetiology, agents, pre-hospital, transportation, femoral shafts, fractures. Introduction ... Disability often results from limb shortening, malalignment, and prolonged .... youngest patient was a day-old baby with a fracture resulting from birth trauma ...

Shifting white pox aetiologies affecting Acropora palmata in the Florida Keys, 1994–2014

Science.gov (United States)

Berry, Brett; Park, Andrew; Kemp, Dustin W.; Kemp, Keri M.; Lipp, Erin K.; Porter, James W.

2016-01-01

We propose ‘the moving target hypothesis’ to describe the aetiology of a contemporary coral disease that differs from that of its historical disease state. Hitting the target with coral disease aetiology is a complex pursuit that requires understanding of host and environment, and may lack a single pathogen solution. White pox disease (WPX) affects the Caribbean coral Acropora palmata. Acroporid serratiosis is a form of WPX for which the bacterial pathogen (Serratia marcescens) has been established. We used long-term (1994–2014) photographic monitoring to evaluate historical and contemporary epizootiology and aetiology of WPX affecting A. palmata at eight reefs in the Florida Keys. Ranges of WPX prevalence over time (0–71.4%) were comparable for the duration of the 20-year study. Whole colony mortality and disease severity were high in historical (1994–2004), and low in contemporary (2008–2014), outbreaks of WPX. Acroporid serratiosis was diagnosed for some historical (1999, 2003) and contemporary (2012, 2013) outbreaks, but this form of WPX was not confirmed for all WPX cases. Our results serve as a context for considering aetiology as a moving target for WPX and other coral diseases for which pathogens are established and/or candidate pathogens are identified. Coral aetiology investigations completed to date suggest that changes in pathogen, host and/or environment alter the disease state and complicate diagnosis. PMID:26880837

[Chewing on bruxism. Diagnosis, imaging, epidemiology and aetiology].

Science.gov (United States)

Lobbezoo, F; Jacobs, R; De Laat, A; Aarab, G; Wetselaar, P; Manfredini, D

2017-06-01

Since the publication of a special issue on bruxism of the NTvT in July 2000, consensus has been reached on bruxism's definition as a repetitive masticatory muscle activity that is characterised by clenching and/or grinding while awake (awake bruxism) or during sleep (sleep bruxism). As yet, however, no consensus exists about the diagnosis of bruxism: sufficient evidence to establish the reliability and validity of the commonly used techniques (self-report, clinical examination, imaging, electromyography, polysomnography) has not yet been produced. Morphological factors are no longer considered important aetiological factors, while increasing evidence suggests aetiological roles for psychosocial, physiological, biological, and exogenous factors. This review paper is the first part of a diptych and is concerned with the definition, diagnostics, epidemiology and possible causes of this disorder. In the second part, that will be published in the next issue, associations of bruxism with other conditions will be discussed, along with its (purported) consequences and its management.

Review of the Aetiology and Complications of Primary Postpartum ...

African Journals Online (AJOL)

Review of the Aetiology and Complications of Primary Postpartum Haemorrhage following vaginal delivery at University of Calabar Teaching Hospital (UCTH), Calabar, Nigeria: A 5-year Review. CI Emechebe, CO Njoku, AN Njoku, JT Ukaga, EM Eyong ...

Occurrence, aetiology and challenges in the management of ...

African Journals Online (AJOL)

Introduction: The aim of the study was to investigate the occurrence, the aetiology and the management of congestive heart failure in the cardiac centre of the St. Elizabeth catholic general hospital Shisong in Cameroon. Methods: Between November 2002 and November 2008, a population of 8121 patients was consulted in ...

The genetic aetiology of cannabis use initiation: A meta-analysis of genome-wide association studies and a SNP-based heritability estimation

NARCIS (Netherlands)

Verweij, K.J.H.; Vinkhuyzen, A.A.E.; Benyamin, B.; Lynskey, M.T.; Quaye, L.; Agrawal, A.; Gordon, S.D.; Montgomery, G.W.; Madden, P.A.F.; Heath, A.C.; Spector, T.D.; Martin, N.G.; Medland, S.E.

2013-01-01

While initiation of cannabis use is around 40% heritable, not much is known about the underlying genetic aetiology. Here, we meta-analysed two genome-wide association studies of initiation of cannabis use with >10000 individuals. None of the genetic variants reached genome-wide significance. We also

Our experience with the aetiological diagnosis of global developmental delay and intellectual disability: 2006-2010.

Science.gov (United States)

López-Pisón, J; García-Jiménez, M C; Monge-Galindo, L; Lafuente-Hidalgo, M; Pérez-Delgado, R; García-Oguiza, A; Peña-Segura, J L

2014-09-01

Global developmental delay (GDD) and intellectual disability (ID) are common reasons for consultation in paediatric neurology. Results from aetiological evaluations of children with GDD/ID vary greatly, and consequently, there is no universal consensus regarding which studies should be performed. We review our experience with determining aetiological diagnoses for children with GDD/ID who were monitored by the paediatric neurology unit over the 5-year period between 2006 and 2010. During the study period, 995 children with GDD/ID were monitored. An aetiological diagnosis was established for 309 patients (31%), but not in 686 (69%), despite completing numerous tests. A genetic cause was identified in 142 cases (46% of the total aetiologies established), broken down as 118 cases of genetic encephalopathy and 24 of metabolic hereditary diseases. Our data seem to indicate that diagnosis is easier when GDD/ID is associated with cerebral palsy, epilepsy, infantile spasms/West syndrome, or visual deficit, but more difficult in cases of autism spectrum disorders. Genetic studies provide an increasing number of aetiological diagnoses, and they are also becoming the first step in diagnostic studies. Array CGH (microarray-based comparative genomic hybridisation) is the genetic test with the highest diagnostic yield in children with unexplained GDD/ID. The cost-effectiveness of complementary studies seems to be low if there are no clinically suspected entities. However, even in the absence of treatment, aetiological diagnosis is always important in order to provide genetic counselling and possible prenatal diagnosis, resolve family (and doctors') queries, and halt further diagnostic studies. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

[AETIOLOGY AND PATHOGENESIS GASTRO-DUODENALES ULCERATIVE LESIONS IN ELDERLY].

Science.gov (United States)

Chernekhovskaya, N E; Povalayev, A V; Layshenko, G A

2015-01-01

In review today conceptions of view to aetiology and pathogenesis gastro-duodenales ulcerative lesions in elderly. Atherosclerosis, ischemic disease of the heart and hypertension are reasons of acute ulcers and erosions in elderly. The breaking of microcirculation are very importance.

Symptoms and aetiology of delirium: a comparison of elderly and adult patients.

Science.gov (United States)

Grover, S; Agarwal, M; Sharma, A; Mattoo, S K; Avasthi, A; Chakrabarti, S; Malhotra, S; Kulhara, P; Bas, D

2013-06-01

OBJECTIVE. To compare the symptoms of delirium as assessed by the Delirium Rating Scale-Revised-98 (DRS-R-98) and associated aetiologies in adult and elderly patients seen in a consultation-liaison service. METHODS. A total of 321 consecutive patients with a DSM-IV-TR diagnosis of delirium were assessed on the DRS-R-98 and a study-specific aetiology checklist. RESULTS. Of the 321 patients, 245 (76%) aged 18 to 64 years formed the adult group, while 76 (24%) formed the elderly group (≥ 65 years). The prevalence and severity of various symptoms of delirium as assessed using the DRS-R-98 were similar across the 2 groups, except for the adult group having statistically higher prevalence and severity scores for thought process abnormalities and lability of affect. For both groups and the whole sample, factor analysis yielded a 3-factor model for the phenomenology. In the 2 groups, the DRS-R-98 item loadings showed subtle differences across various factors. The 2 groups were similar for the mean number of aetiologies associated with delirium, the mean number being 3. However, the 2 groups differed with respect to hepatic derangement, substance intoxication, withdrawal, and postpartum causes being more common in the adult group, in contrast lung disease and cardiac abnormalities were more common in the elderly group. CONCLUSION. Adult and elderly patients with delirium are similar with respect to the distribution of various symptoms, motor subtypes, and associated aetiologies.

Damage mechanisms in PBT-GF30 under thermo-mechanical cyclic loading

International Nuclear Information System (INIS)

Schaaf, A.; De Monte, M.; Hoffmann, C.; Vormwald, M.; Quaresimin, M.

2014-01-01

The scope of this paper is the investigation of damage mechanisms at microscopic scale on a short glass fiber reinforced polybutylene terephthalate (PBT-GF30) under thermo-mechanical cyclic loading. In addition the principal mechanisms are verified through micro mechanical FE models. In order to investigate the fatigue behavior of the material both isothermal strain controlled fatigue (ISCF) tests at three different temperatures and thermo-mechanical fatigue (TMF) tests were conducted on plain and notched specimens, manufactured by injection molding. The goal of the work is to determine the damage mechanisms occurring under TMF conditions and to compare them with the mechanisms occurring under ISCF. For this reason fracture surfaces of TMF and ISCF samples loaded at different temperature levels were analyzed using scanning electron microscopy. Furthermore, specimens that failed under TMF were examined on microsections revealing insight into both crack initiation and crack propagation. The findings of this investigation give valuable information about the main damage mechanisms of PBT-GF30 under TMF loading and serve as basis for the development of a TMF life estimation methodology

Multiple aneurysm of unknown aetiology in childhood: Complications and diagnostic possibilities

International Nuclear Information System (INIS)

Lanfermann, H.; Benz-Bohm, G.; Schaper, J.; Gross-Fengels, W.

1990-01-01

A 6,5-year old boy with already known multiple aneurysm of all major arteries presented with acute abdominal pain. As demonstrated by ultrasound a big aneurysm of the left renal artery thrombosed in the course of three days. As a result, the left kidney developed severe ischaemia. Although computed tomography and scintigraphy were applied, a plan for a definitive therapeutic procedere could be established only by arterial angiography. Both Ehlers-Danlos' syndrome and Kawasaki's syndrome were excluded. There were no facts suggesting an infective aetiology. Four other cases with multiple aneurysms of unknown aetiology in childhood have so far been described in literature. (orig.) [de

TS-EUROTRAIN: A European-wide investigation and training network on the aetiology and pathophysiology of Gilles de la Tourette Syndrome

Directory of Open Access Journals (Sweden)

Natalie J Forde

2016-08-01

Full Text Available Gilles de la Tourette Syndrome (GTS is characterised by the presence of multiple motor and phonic tics with a fluctuating course of intensity, frequency and severity. Up to 90% of patients with GTS present with comorbid conditions, most commonly attention-deficit/hyperactivity disorder (ADHD and obsessive-compulsive disorder (OCD, thus providing an excellent model for the exploration of shared aetiology across disorders. TS-EUROTRAIN (FP7-PEOPLE-2012-ITN, Grant Agr.No.316978 is a Marie Curie Initial Training Network (http://ts-eurotrain.eu that aims to elucidate the complex aetiology of the onset and clinical course of GTS, investigate the neurobiological underpinnings of GTS and related disorders, translate research findings into clinical applications and establish a pan-European infrastructure for the study of GTS. This includes the challenges of (i assembling a large genetic database for the evaluation of the genetic architecture with high statistical power; (ii exploring the role of gene-environment interactions including the effects of epigenetic phenomena; (iii employing endophenotype-based approaches to understand the shared aetiology between GTS, OCD and ADHD; (iv establishing a developmental animal model for GTS; (v gaining new insights into the neurobiological mechanisms of GTS via cross-sectional and longitudinal neuroimaging studies; and (vi partaking in outreach activities including the dissemination of scientific knowledge about GTS to the public. Fifteen partners from academia and industry and twelve PhD candidates pursue the project. Our ultimate aims are to elucidate the complex aetiology and neurobiological underpinnings of GTS, translate research findings into clinical applications and establish Pan-European infrastructure for the study of GTS and associated disorders.

[Scoliosis: review of types, aetiology, diagnostics, and treatment 1

NARCIS (Netherlands)

de Baat, P.; van Biezen, E.C.; de Baat, C.

2012-01-01

A scoliosis is a flexible or rigid deformity of the spine in the frontal plane. There are several types of scoliosis, each with specific characteristics. The most prevalent types are idiopathic, congenital, and neuromuscular scoliosis and scoliosis in adults. The aetiology is varied and largely

Getting the phenotypes right: an essential ingredient for understanding aetiological mechanisms underlying persistent violence and developing effective treatments

Directory of Open Access Journals (Sweden)

Sheilagh Hodgins

2009-11-01

Full Text Available In order to reduce societal levels of violence, it is essential to advance understanding of the neurobiological mechanisms involved in initiating and maintaining individual patterns of physical aggression. New technologies such as Magnetic Resonance Imagining and analyses of DNA provide tools for identifying these mechanisms. The reliability and validity of the results of studies using these tools depend not only on aspects of the technology, but also on the methodological rigour with which the studies are conducted, particularly with respect to characterizing the phenotype. The present article discusses five challenges confronting scientists who aim to advance understanding of the neurobiological mechanisms associated with persistent violence. These challenges are: (1 to develop evidence-based hypotheses and to design studies that test alternate hypotheses; (2 to recruit samples that are homogeneous with respect to variables that may be linked to neurobiological mechanisms underpinning violent behaviour; (3 to use reliable and valid measures in order to fully characterize participants so that the external validity of the results is evident; (4 to restrict the range of age of participants so as not to confuse developmental change with group differences; and (5 to take account of sex. Our goal is to contribute to elevating methodological standards in this new field of research and to thereby improve the validity of results and move closer to finding effective ways to reduce violence

The aetiology of idiopathic scoliosis : biomechanical and neuromuscular factors

NARCIS (Netherlands)

Veldhuizen, AG; Webb, PJ

The aetiology of adolescent idiopathic scoliosis (AIS) remains an enigma. In the literature there are two opinions: one believes a deviating growth pattern is responsible for the condition - patients with AIS lend to be growing faster/be taller - while the other opinion assumes that the growth

Epilepsy in sub-Saharan Africa: its socio-demography, aetiology ...

African Journals Online (AJOL)

Objective: To assess epileptics with regard to socio-demographic characteristics, aetiology, EEG results and classification. Design: A descriptive cohort study from 1997 to 2001. Setting: Parirenyatwa Group of Hospitals in Harare, Zimbabwe. Subjects: A total of 229 consecutive epileptic subjects. Results: The mean (s.d.) ...

Pathophysiology and aetiology of impaired fasting glycaemia and impaired glucose tolerance: does it matter for prevention and treatment of type 2 diabetes?

DEFF Research Database (Denmark)

Faerch, K; Borch-Johnsen, K; Holst, Jens Juul

2009-01-01

Prior to the development of type 2 diabetes, glucose levels increase into the prediabetic states of isolated impaired fasting glycaemia (i-IFG), isolated impaired glucose tolerance (i-IGT), or combined IFG/IGT. A better understanding of the aetiology and pathophysiology of the prediabetic states...... might give a basis for the development of individualised prevention and treatment strategies for type 2 diabetes. Several studies have examined mechanisms and potential aetiological factors leading to the development of the different prediabetic states. The pathophysiology of i-IFG seems to include...... the following key defects: reduced hepatic insulin sensitivity, stationary beta cell dysfunction and/or chronic low beta cell mass, altered glucagon-like peptide-1 secretion and inappropriately elevated glucagon secretion. Conversely, the prediabetic state i-IGT is characterised by reduced peripheral insulin...

Aetiology, imaging and treatment of medial tibial stress syndrome

NARCIS (Netherlands)

Moen, M.H.

2012-01-01

The work contained is this thesis discusses aetiology, imaging and treatment of a common leg injury: medial tibial stress syndrome (MTSS). Although a common injury, the number of scientific articles on this topic is relatively low as is explained in chapter 1. This chapter also highlights that the

Aetiology of molar-incisor hypomineralisation (MIH) in Brazilian children.

Science.gov (United States)

Souza, J F; Jeremias, F; Costa-Silva, C M; Santos-Pinto, L; Zuanon, A C C; Cordeiro, R C L

2013-06-25

To determine the potential aetiological factors related to molar-incisor hypomineralisation (MIH) in Brazilian children. A total of 1,151 children aged 7-12 years (mean 8.86 ± 1.28), born and living in the urban area of Araraquara, Brazil, were examined by two examiners evaluating the presence of MIH according to criteria suggested by the European Academy of Paediatric Dentistry (2003). Their mothers completed a structured questionnaire about medical history, from pregnancy to the first 3 years of the children's life. Descriptive analyses of data and odds ratios (OR) with 95 % test-based confidence intervals (CI) were estimated. Chi-square test was used to evaluate the differences between groups. The prevalence of MIH in the children was 12.3 %. The interviewing response rate was 90.4 %. The prevalence of miscarriage history (25 vs. 15.4 %; OR = 1.21; 95 % CI 0.30-4.92) and occurrence of anaemia (23 vs. 12.4 %; OR = 2.07; 95 % CI 0.50-8.63) were higher in mothers from MIH group than those from non-MIH group. However, these associations were not statically significant. In the children's medical history, rhinitis, bronchitis (56.5 vs. 52.5 %; OR = 1.17; 95 % CI 0.82-1.68), and high fever (20.4 vs. 18.2 %; OR = 1.14; 0.73-1.76) were more prevalent in MIH group, but there were no significant differences between the groups (p > 0.05). No possible aetiological factor investigated was associated with MIH. Prospective studies are needed to define the aetiological factors involved with MIH.

Clinical presentation, aetiology and complications of pancreatitis in children

International Nuclear Information System (INIS)

Fayyaz, Z.; Cheema, H.A.; Suleman, H.; Hashmi, M.A.; Parkash, A.; Waheed, N.

2015-01-01

Background: Childhood Pancreatitis is an uncommon but serious condition with incidence on the rise. It manifests as acute or chronic form with epigastric pain, vomiting and elevated serum -amylase and lipase. This study was conducted with the aim to determine the clinical presentation, aetiology, and complications of pancreatitis in children. Method: This descriptive case series was conducted in the Department of Paediatric Gastroenterology, Hepatology and Nutrition, The Children's Hospital and the Institute of Child Health, Lahore from 1st January to 31st December 2014. Seventy-two patients up to the age of 15 years having abdominal pain, Amylase >200 IU/L and/or lipase >165 IU/L, with features of acute or chronic pancreatitis on abdominal imaging; were included in study. Data analysis was done using SPSS-20. Results: Of the total 72 patients, 43 (60 percentage) had acute pancreatitis, males were 25 (58 percentage) and females 18 (42 percentage) and chronic pancreatitis was diagnosed in 29 (40 percentage), males 10 (34 percentage) and females 19 (66 percentage). Common clinical features were abdominal pain (100 percentage), nausea and vomiting (79 percentage). Common aetiologies were idiopathic (40 percentage) while choledochal cyst 8 percentage, hyperlipidaemia 7 percentage, biliary tract stones/sludge 7 percentage and abdominal trauma 6percentage. Complications were more frequently associated with acute pancreatitis (60 percentage) than with chronic pancreatitis (34 percentage). Common complications were pseudo-pancreatic cyst (36 percentage), ascites (17 percentage) and pleural effusion (4 percentage). Conclusion: Abdominal pain, nausea and vomiting were common presenting features of childhood pancreatitis. Common aetiologies were idiopathic hyperlipidemia, biliary tract stones/sludge, choledochal cyst and abdominal trauma. Common complications were Pseudo-pancreatic cyst, ascites and pleural effusion. (author)

Schizophrenia : Current concepts in aetiology

Directory of Open Access Journals (Sweden)

P S Bhat

2014-01-01

Full Text Available Schizophrenia is perhaps the most devastating neuropsychiatric illness. Worldwide, its prevalence rate is about 1%. Schizophrenia is considered a neurodevelopmental disorder involving the interplay of susceptibility genes and environmental factors. There is a wide range of pathologic findings, but there is no specific or diagnostic laboratory abnormality. Till date, the aetiology, neuropathology, and pathophysiology of schizophrenia remain elusive. Over the last forty years, the dopaminergic model has been the leading neurochemical hypothesis of schizophrenia. Yet it remains unlikely that dopaminergic dysfunction, on its own. Glutamatergic models provide an alternate approach for conceptualizing the brain abnormalities associated with schizophrenia. New pharmacological and behavioral approaches aimed at potentiating glutamatergic neurotransmission, offer new hopeforfuture clinical development

Multiple constitutional aetiological factors in bone marrow failure syndrome (BMFS) patients from north India.

Science.gov (United States)

Varma, Neelam; Varma, Subhash; Marwaha, Ram Kumar; Malhotra, Pankaj; Bansal, Deepak; Malik, Kiran; Kaur, Sukhdeep; Garewal, Gurjeevan

2006-07-01

A large number of patients diagnosed with bone marrow failure syndromes (BMFS), comprising aplastic anaemia (AA) and myelodysplastic syndromes (MDS), remain aetiologically uncharacterized worldover, especially in resource constrained set up. We carried out this study to identify a few constitutional causes in BMFS patients attending a tertiary care hospital in north India. Peripheral blood lymphocyte cultures were performed (with and without clastogens) in a cohort of 135 consecutive BMFS patients, in order to detect Fanconi anaemia (FA), Down's syndrome (+21), trisomy 8 (+8) and monosomy 7 (-7). Constitutional factors were detected in 17 (12.6%) patients. FA defect was observed in 24.07 percent (13/54), 16.66 percent (1/6) and 2.85 percent (1/35) paediatric aplastic anaemia, paediatric MDS and adult MDS patients respectively. Down's syndrome was detected in 5.00 percent (2/40) adult aplastic anaemia patients. None of the patients revealed trisomy 8 or monosomy 7. Presence of an underlying factor determines appropriate management, prognostication, family screening and genetic counselling of BMFS patients. Special tests required to confirm or exclude constitutional aetiological factors are not available to majority of the patients in our country. Diepoxybutane (DEB) test yielded better results than mitomycin C (MMC) test in our experience.

Dental Erosion and Medical Conditions: An Overview of Aetiology, Diagnosis and Management.

Science.gov (United States)

Paryag, A; Rafeek, R

2014-09-01

Tooth wear or tooth surface loss is a normal physiological process and occurs throughout life but is considered pathological when the degree of destruction is excessive or the rate of loss is rapid, causing functional, aesthetic or sensitivity problems. The importance of tooth wear as a dental problem has been increasingly recognized. The findings of a study in Trinidad indicate that the prevalence of tooth wear in a Trinidadian population is comparable to the United Kingdom (UK) and, indeed, that the level of moderate and severe wear is in fact nearly twice as high. The aetiology of tooth wear is attributed to four causes: erosion, attrition, abrasion and abfraction. Erosion is generally considered to be the most prevalent cause of tooth wear in the UK and Europe. Acids that cause dental erosion originate mainly from the diet or the stomach and to a lesser extent, the environment. Underlying medical problems can contribute to the progress of tooth wear due to erosion and the patient may not be aware of these conditions. Moderate to severe tooth wear poses a significant clinical challenge to dental practitioners and may result in treatment that is more complex and costly to the patient both in terms of finances and time spent in the dental chair. This paper provides an overview of aetiology and diagnosis of tooth wear, in particular tooth wear due to erosion, so that medical and dental practitioners may recognize tooth wear early, institute preventive measures and manage patients appropriately.

Aetiology and pathology of otitis media with effusion in adult life.

Science.gov (United States)

Mills, R; Hathorn, I

2016-05-01

To gather and analyse information concerning the aetiology and pathology of otitis media with effusion in adults. A review of the English language literature from 1970 to the present was conducted. The available evidence suggests that otitis media with effusion in adult life is best viewed as a syndrome with a number of causes, including: infiltration of the eustachian tube by nasopharyngeal carcinoma and other local malignancies; changes in the middle ear and eustachian tube induced by radiotherapy; and systemic disease. There is now a body of evidence specifically related to the aetiology and pathology of otitis media with effusion in adult life. However, further research is required to fill in the gaps in our knowledge and understanding of this condition.

Aetiology of hypospadias: a systematic review of genes and environment.

NARCIS (Netherlands)

Zanden, L.F.M. van der; Rooij, I.A.L.M. van; Feitz, W.F.J.; Franke, B.; Knoers, N.V.A.M.; Roeleveld, N.

2012-01-01

BACKGROUND: Hypospadias is a common congenital malformation of the male external genitalia. Most cases have an unknown aetiology, which is probably a mix of monogenic and multifactorial forms, implicating both genes and environmental factors. This review summarizes current knowledge about the

A STUDY OF AETIOLOGICAL FACTORS IN THE OCCURRENCE OF CUTANEOUS VASCULITIS IN A TERTIARY CARE CENTRE IN NORTH KERALA

Directory of Open Access Journals (Sweden)

Praveen Malayath

2017-03-01

Full Text Available BACKGROUND Cutaneous vasculitis is a condition caused by various aetiologies. They can be primary or secondary. Cutaneous lesions maybe a pointer to systemic diseases. So, it is important to identify the various aetiological factors in the occurrence of the various types of cutaneous vasculitis. The patterns and the various aetiologies of cutaneous vasculitis in Kerala is not well documented in the existing literature. MATERIALS AND METHODS The present study is a cross-sectional descriptive study of patients with a clinical diagnosis of cutaneous small vessel vasculitis admitted in Medicine and Dermatology Wards of Calicut, Government Medical College during January 2013 to December 2013. A detailed history and clinical examination of patients along with histopathological examination of skin biopsy was done. RESULTS Out of the 70 cases of cutaneous vasculitis studied, idiopathic cutaneous small vessel vasculitis was the most common type followed by Henoch-Schonlein purpura. The most common aetiology identified was drugs followed by infections. No aetiological factor was identified in 42.8% of the cases. CONCLUSION An aetiological association could be found in 57.8% of cases. The causes identified include drugs, infections, malignancy, connective tissue disorder associated, chronic systemic diseases and Behcet’s disease in decreasing order of frequency.

An investigation into febrile illnesses of unknown aetiology in Wipim, Papua New Guinea.

Science.gov (United States)

Bande, Grace; Hetzel, Manuel W; Iga, Jonah; Barnadas, Celine; Mueller, Ivo; Siba, Peter M; Horwood, Paul F

2014-01-01

In Papua New Guinea the aetiology of febrile illnesses remains poorly characterized, mostly due to poor diagnostic facilities and the inaccessibility of much of the rural areas of the country. We investigated the aetiological agents of febrile illnesses for 136 people presenting to Wipim Health Centre in Western Province, Papua New Guinea. Arboviral and rickettsial real-time polymerase chain reaction (PCR) assays, malaria blood smears and a malaria PCR test were used to identify pathogens associated with a history of fever. In 13% (n = 18) of cases an aetiological agent was identified. Dengue virus type 1 was detected in 11% (n = 15) of the samples tested and malaria in 2% (n = 3). None of the other arboviral or rickettsial pathogens tested for were detected in any of the samples. Although dengue viruses have been identified in Papua New Guinea using serological methods, this study represents the first direct detection of dengue in the country. The detection of malaria, on the other hand, was surprisingly low considering the previous notion that this was a hyperendemic region of Papua New Guinea.

Aetiology of Oral Cancer in the Sudan

OpenAIRE

Ahmed, Hussain Gadelkarim

2013-01-01

ABSTRACT Objectives To review the studied risk factors that linked to aetiology of oral cancer in the Sudan. There have been numerous reports in the increase in the incidence of oral cancer from various parts of the world. A recent trend for a rising incidence of oral cancer, with the absence of the well established risk factors, has raised concern. Although, there are inconsistent data on incidence and demographical factors, studies suggest that the physiologic response to risk factors by me...

Permanent Childhood Hearing Impairment: Aetiological Evaluation of Infants identified through the Irish Newborn Hearing Screening Programme

LENUS (Irish Health Repository)

Smith, A

2017-11-01

The Newborn Hearing Screening Programme (NHSP) was established in Cork University Maternity Hospital (CUMH) in April 2011. Between April 2011 and July 2014, 42 infants were identified with a Permanent Childhood Hearing Impairment (PCHI). Following this diagnosis, infants underwent a paediatric assessment according to recognised guidelines with the intention of identifying the underlying aetiology of the PCHI. The aim of this study was to assess the findings of this aetiological workup via retrospective chart review. PCHI data was obtained from the eSP database. This is a web based information system (eSP) used to track each baby through the screening and referral process A retrospective chart review of these patients was performed. Sixteen (38%) infants were diagnosed with a bilateral sensorineural hearing loss. Two infants had congenital CMV infection. A Connexin 26 gene mutation was detected in one infant. Two infants were diagnosed with Waardenburg syndrome, One with Pendred syndrome and one with Pfeiffer syndrome. Five babies underwent cochlear implantation. Through adherence to the recommended protocol a possible cause of PCHI may be determined. This study has identified areas of future improvement for this service in Ireland.

Risk factors, aetiology and outcome of ischaemic stroke in young adults: the Swiss Young Stroke Study (SYSS).

Science.gov (United States)

Goeggel Simonetti, Barbara; Mono, Marie-Luise; Huynh-Do, Uyen; Michel, Patrik; Odier, Celine; Sztajzel, Roman; Lyrer, Philippe; Engelter, Stefan T; Bonati, Leo; Gensicke, Henrik; Traenka, Christopher; Tettenborn, Barbara; Weder, Bruno; Fischer, Urs; Galimanis, Aekaterini; Jung, Simon; Luedi, Rudolf; De Marchis, Gian Marco; Weck, Anja; Cereda, Carlo W; Baumgartner, Ralf; Bassetti, Claudio L; Mattle, Heinrich P; Nedeltchev, Krassen; Arnold, Marcel

2015-09-01

Ischaemic stroke (IS) in young adults has been increasingly recognized as a serious health condition. Stroke aetiology is different in young adults than in the older population. This study aimed to investigate aetiology and risk factors, and to search for predictors of outcome and recurrence in young IS patients. We conducted a prospective multicentre study of consecutive IS patients aged 16-55 years. Baseline demographic data, risk factors, stroke aetiology including systematic genetic screening for Fabry disease and severity were assessed and related to functional neurological outcome (modified Rankin Scale, mRS), case fatality, employment status, place of residence, and recurrent cerebrovascular events at 3 months. In 624 IS patients (60% men), median age was 46 (IQR 39-51) years and median NIHSS on admission 3 (IQR 1-8). Modifiable vascular risk factors were found in 73%. Stroke aetiology was mostly cardioembolism (32%) and of other defined origin (24%), including cervicocerebral artery dissection (17%). Fabry disease was diagnosed in 2 patients (0.3%). Aetiology remained unknown in 20%. Outcome at 3 months was favourable (mRS 0-1) in 61% and fatal in 2.9%. Stroke severity (p young adults with IS had modifiable vascular risk factors, emphasizing the importance of prevention strategies. Outcome was unfavourable in more than a third of patients and was associated with initial stroke severity and diabetes mellitus. Previous cerebrovascular events predicted recurrent ones.

Multiple aetiologies of secondary hypertension in one patient

OpenAIRE

Golan, Eliezer; Nabriski, Danny; Sharabi, Yehonatan; Werner, Miryam; Griton, Yigal; Moshkovich, Evgeny; Korzets, Ze?ev

2008-01-01

Apart from seeking target organ damage, the investigation of hypertension is primarily aimed at finding a treatable cause of the hypertension. The finding of one such cause is usually construed as being the sole culprit responsible for the patient's elevated blood pressure. The existence of multiple aetiologies of secondary hypertension in one patient is infrequent. In this report, we describe such a patient in whom secondary hypertension due to Cushing's disease, renovascular and finally bar...

Sonography of gallstones and biliary dilatation without a visible aetiology: The infrequency of obstructing choledocholithiasis

International Nuclear Information System (INIS)

Cabrera, O.; Van Sonnenberg, E.; Wittich, G.R.; Leopold, G.R.; Gosink, U.B.; Bowen, J.S.; California Univ., San Diego, La Jolla

1988-01-01

This paper describes 50 consecutive patients who sonographically had gallbladder stones and dilated bile ducts, but no visible aetiology for the dilatation. We reviewed these cases to determine the frequency of choledocholithiasis in this setting. Common duct stones caused obstruction in only 36% of these patients. Other aetiologies included strictures due to chronic pancreatitis or prior stone passage in 24% of the patients, and malignant obstruction in 16%. In 24% of the patients, no cause was found for biliary dilatation: common duct stones or obstructing tumours were excluded in the group. Since aetiologies other than stones are likely in a majority of cases, further preoperative workup (CT, percutaneous transhepatic cholangiography, ERCP) or intraoperative cholangiography (if the patient requires urgent cholecystectomy) is indicated. The additional studies should provide a diagnosis, help determine whether or not the common duct should be explored, or avoid unnecessary operation in case of incurable malignancy. (orig.)

[Aspects of aetiology of neuro-psychic disorders in male liquidators of Chernobyl nuclear power accident consequences].

Science.gov (United States)

Skavysh, V A

2009-01-01

The author considered aetiology of neuro-psychic disorders in liquidators of Chernobyl nuclear power accident consequences, demonstrated scientific value of studying the liquidators cohort, as they were protected from internal radiation factors and reside on radiation "pure" territories. External radiation doses in those liquidators vary from 16 cGy to 18.7 +/- 10.8 cGy, according to the author. Catamnesis enabled to doubt radiation aetiology of psychic organic syndrome revealed in 1991-1994 by clinical and instrumental studies among 53.6% of 213 male examinees. According to the author, prolonged over 1-2 months external radiation of low dose could not cause health deterioration in adult males. Diagnosed psychic organic syndrome and vascular encephalopathy in some cases could have alcohol aetiology. This conclusion is not extrapolated to the whole liquidators cohort.

Neonatal seizures : Aetiology by means of a standardized work-up

NARCIS (Netherlands)

Loman, Annemiek M. W.; ter Horst, Henk J.; Lambrechtsen, Florise A. C. P.; Lunsing, Roelineke J.

Neonatal seizures are an alarming symptom and are frequent in neonates. It is important to find the cause of neonatal seizures to start a specific treatment and to give a meaningful prognosis. The aim of this study is to investigate the incidence of different aetiologies of neonatal seizures in our

Influence of obesity-related risk factors in the aetiology of glioma

DEFF Research Database (Denmark)

Disney-Hogg, Linden; Sud, Amit; Law, Philip J

2018-01-01

BACKGROUND: Obesity and related factors have been implicated as possible aetiological factors for the development of glioma in epidemiological observation studies. We used genetic markers in a Mendelian randomisation framework to examine whether obesity-related traits influence glioma risk. This ...

Spontaneous chylothorax complicating small cell lung cancer – Review of aetiology and diagnosis

Directory of Open Access Journals (Sweden)

S. Hanina

2015-01-01

Full Text Available We report the first case of spontaneous chylothorax complicating small cell lung cancer. A 52 year old female presented with exertional dyspnoea, left-sided chest and neck pain, and dysphagia. The chest X-ray on admission revealed a large left-sided pleural effusion. A subsequent CT chest showed a large anterior mediastinal mass with a left brachiocephalic and jugular vein thrombosis. The patient underwent medical thoracoscopy with chest drain insertion, which drained pleural fluid high in triglycerides, consistent with a chylothorax. Due to its uncommon nature, the management of chylothorax is not well defined. Alongside the case report, we provide a review of aetiology, mechanism and diagnosis with a brief summary of treatment options.

Aetiological profile of nasal trauma in Ilorin North-Central Nigeria ...

African Journals Online (AJOL)

Background: The nose being the most prominent part of the face is easily traumatized in facial injuries and these has been found to be common among the Caucasians compared to the Africans and Asians. The aim is to ighlight the Aetiological profile of nasal trauma in Ilorin orth-central Nigeria. Method: A prospective study ...

Childhood acute non-traumatic coma: aetiology and challenges in management in resource-poor countries of Africa and Asia.

Science.gov (United States)

Gwer, Samson; Chacha, Clifford; Newton, Charles R; Idro, Richard

2013-08-01

This review examines the best available evidence on the aetiology of childhood acute non-traumatic coma in resource-poor countries (RPCs), discusses the challenges associated with management, and explores strategies to address them. Publications in English and French which reported on studies on the aetiology of childhood non-traumatic coma in RPCs are reviewed. Primarily, the MEDLINE database was searched using the keywords coma, unconsciousness, causality, aetiology, child, malaria cerebral, meningitis, encephalitis, Africa, Asia, and developing countries. 14 records were identified for inclusion in the review. Cerebral malaria (CM) was the commonest cause of childhood coma in most of the studies conducted in Africa. Acute bacterial meningitis (ABM) was the second most common known cause of coma in seven of the African studies. Of the studies in Asia, encephalitides were the commonest cause of coma in two studies in India, and ABM was the commonest cause of coma in Pakistan. Streptococcus pneumoniae was the most commonly isolated organism in ABM. Japanese encephalitis, dengue fever and enteroviruses were the viral agents most commonly isolated. Accurate diagnosis of the aetiology of childhood coma in RPCs is complicated by overlap in clinical presentation, limited diagnostic resources, disease endemicity and co-morbidity. For improved outcomes, studies are needed to further elucidate the aetiology of childhood coma in RPCs, explore simple and practical diagnostic tools, and investigate the most appropriate specific and supportive interventions to manage and prevent infectious encephalopathies.

CLINICO-AETIOLOGICAL STUDY OF LOWER MOTOR NEURON FACIAL PALSY

Directory of Open Access Journals (Sweden)

Souvagini Acharya

2017-05-01

Full Text Available BACKGROUND The facial nerve paralysis is a broad term having so many differential diagnoses starting from congenital causes to malignant tumour. Accurate diagnosis with localisation of the site of injury or compression and timely intervention has become a challenge to an otorhinolaryngologist. Objective- To outline the incidence of the different aetiologies and the profile of peripheral facial nerve paralysis patients in the Otolaryngology Dept. of ENT in VIMSAR, Burla. MATERIALS AND METHODS The records of 53 patients with facial nerve paralysis seen during the years of 2016 & 2017 were analysed. RESULTS From the 53 patients analysed, 60.4% were male, maximum cases 35.85% were in 3 rd decade of age and had the right side of the face involved in 62.26%. Bell´s palsy was the most frequent aetiology (66.04%, others are traumatic (11.32%, Ramsay Hunt syndrome (1.89%, CSOM (16.98%, malignant otitis externa (1.89%. One case of Bell´s palsy during pregnancy was also seen in this series. CONCLUSION The data found are similar to the most of the literature showing that Bell´s palsy is still the most frequent. Males are more commonly affected with a preponderance to involve right side of face.

Pathophysiological mechanisms of severe anaemia in Malawian children.

Directory of Open Access Journals (Sweden)

Michaël Boele van Hensbroek

2010-09-01

Full Text Available Severe anaemia is a major cause of morbidity and mortality in African children. The aetiology is multi-factorial, but interventions have often targeted only one or a few causal factors, with limited success.We assessed the contribution of different pathophysiological mechanisms (red cell production failure [RCPF], haemolysis and blood loss to severe anaemia in Malawian children in whom etiological factors have been described previously. More complex associations between etiological factors and the mechanisms were explored using structural equation modelling. In 235 children with severe anaemia (haemoglobin<3.2 mMol/L [5.0 g/dl] studied, RCPF, haemolysis and blood loss were found in 48.1%, 21.7% and 6.9%, respectively. The RCPF figure increased to 86% when a less stringent definition of RCPF was applied. RCPF was the most common mechanism in each of the major etiological subgroups (39.7-59.7%. Multiple aetiologies were common in children with severe anaemia. In the final model, nutritional and infectious factors, including malaria, were directly or indirectly associated with RCPF, but not with haemolysis.RCPF was the most common pathway leading to severe anaemia, from a variety of etiological factors, often found in combination. Unlike haemolysis or blood loss, RCPF is a defect that is likely to persist to a significant degree unless all of its contributing aetiologies are corrected. This provides a further explanation for the limited success of the single factor interventions that have commonly been applied to the prevention or treatment of severe anaemia. Our findings underline the need for a package of measures directed against all of the local aetiologies of this often fatal paediatric syndrome.

Aetiology of allergic rhinitis in Hong Kong

Directory of Open Access Journals (Sweden)

Christopher W.K. Lam

1998-01-01

Full Text Available In a 1993 survey, allergic rhinitis was identified as the most common allergic disease in Hong Kong, affecting 29.1% of schoolchildren. Recently (1995, the International Study of Asthma and Allergies in Childhood (ISAAC also reported 44.5% current rhinitis among Hong Kong teenagers. Our objective was to study the aetiology of allergic rhinitis in Hong Kong using serological tests of allergen sensitization. In 57 allergic rhinitis patients and in the same number of age- and sex-matched controls the following were measured: serum total IgE, mixed aeroallergen IgE (Phadiatop™ and specific IgE versus house dust mite (HDM, cockroach, cat and dog dander, mould mixture (Penicillium, Cladosporium, Aspergillus and Alternaria species and four local pollens (Bermuda grass, Timothy, ragweed and mugwort. Compared with controls, allergic rhinitis patients (26 males, 31 females; mean (± SD age 25 ±11 years had a significantly elevated serum total IgE concentration (mean ± SEM: 496 ± 88 vs 179 ± 38 kU/L and an increased proportion of positive Phadiatop (95 vs 33% and specific IgE tests versus HDM (90 vs 44% and cockroach (42 vs 9%; Mann-Whitney U-test and χ2 tests all P < 0.005. There was no significant difference in sensitization to other allergens tested. House dust mite and cockroach are ubiquitous in Hong Kong with a warm, humid climate and crowded living conditions. Their identification as aetiological agents of allergic rhinitis should help in the development of environmental strategies for reducing the inhalant allergen load to prevent and control this prevalent and costly health problem in our community.

Morphological and biochemical characterization of the aetiological agents of white piedra.

Science.gov (United States)

Magalhães, Alba Regina; Mondino, Silvia Susana Bona de; Silva, Manuela da; Nishikawa, Marilia Martins

2008-12-01

The Trichosporon genus is constituted by many species, of which Trichosporon ovoides and Trichosporon inkin are the causative agents of white piedra. They can cause nodules in genital hair or on the scalp. At present, Brazilian laboratory routines generally do not include the identification of the species of Trichosporon genus, which, although morphologically and physiologically distinct, present many similarities, making the identification difficult. The aim of this study was to identify the aetiological agents at the species level of white piedra from clinical specimens. Therefore, both the macro and micro morphology were studied, and physiological tests were performed. Trichosporon spp. was isolated from 10 clinical samples; T. ovoides was predominant, as it was found in seven samples, while T. inkin was identified just in two samples. One isolate could not be identified at the species level. T. inkin was identified for the first time as a white piedra agent in the hair shaft on child under the age of 10.

Clinical profile and aetiology of optic neuritis in Hospital Universiti Sains Malaysia--5 years review.

Science.gov (United States)

Ismail, Shatriah; Wan Hazabbah, Wan Hitam; Muhd-Nor, Nor-Idahriani; Daud, Jakiyah; Embong, Zunaina

2012-04-01

Although few studies concerning optic neuritis (ON) in Asian countries have been reported, there is no report about ON in Malaysia particularly within the Malay population. We aimed to determine the clinical manifestation, visual outcome and aetiology of ON in Malays, and discussed the literature of ON studies in other Asian populations. This was a retrospective study involving 31 consecutive patients (41 eyes) with ON treated at Hospital Universiti Sains Malaysia commencing from July 2005 till January 2010 with a period of follow-up ranging from 18-60 months. The clinical features, laboratory results, possible aetiology, and visual acuity after one year were analysed. Females were the predominant group. The age of the patients ranged between 3-55 years and peaked between 21-30 years old. 67.7% of the patients had unilateral involvement. Pain on ocular movement was observed in 31.7% of the affected eyes. 73.3% of 41 involved eyes showed visual acuity equal 6/60 or worse on presentation. Paracentral scotoma was the most common visual field defect noted. Optic disc papillitis proved more widespread compared to the retrobulbar type of ON. The aetiology was idiopathic in more than 50%, while the risk of multiple sclerosis was extremely low (3.2%) in our series. 66.0% demonstrating visual acuity improved to 6/12 or better at one year after the attack. 16.1% showed evidence of recurrence during follow-up. In conclusion, the clinical profile and aetiology of ON in Malay patients are comparable to other ON studies reported by other Asian countries.

Relationship between Traditional Chinese Beliefs about Aetiology of Mental Disorders and Help Seeking: A Survey of the Elderly in Macao.

Science.gov (United States)

Found, A

2016-03-01

A wide range of factors can influence help-seeking attitudes when individuals experience a mental disorder. The current study investigated the relationship between traditional Chinese beliefs related to the aetiology of mental disorders and help-seeking attitudes among elderly participants in Macao. In order to ensure the suitability of participants for inclusion in this study, the participants were required to complete an initial screening test using the Short Portable Mental Status Questionnaire (SPMSQ). Participants who successfully passed the test (n = 183) completed a questionnaire that included the Inventory of Attitudes Toward Seeking Mental Health Services (IASMHS), a set of 9 items related to traditional Chinese beliefs about aetiology of mental disorders and demographic items. The IASMHS scores were higher for female participants and for participants who had completed high school compared with those who had never attended school or who had only completed primary education. Endorsement of traditional Chinese beliefs about the aetiology of mental disorders was higher for male participants. There was a negative correlation between traditional Chinese aetiology beliefs related to mental disorders and help-seeking attitudes. Traditional Chinese beliefs related to the aetiology of mental disorders are a negative factor that inhibits help seeking. Implications for efforts to increase the utilisation of mental health services by the elderly are discussed.

Epidemiology, aetiology, diagnosis and screening of lung cancer

International Nuclear Information System (INIS)

Berzinec, P.

2006-01-01

Lung cancer is the leading cause of cancer death globally. Smoking causes about 90 % of all lung cancer cases. Passive, i.e. involuntary smoking has been confirmed to enhance the risk of lung cancer in exposed people. Individual susceptibility is one of important factors in lung cancer formation. New knowledge in epidemiology and aetiology of lung cancer gives new possibilities in diagnostic and screening of this disease. Results of large randomised trials aimed at new technologies in lung cancer screening will be available in a few years. (author)

Surface Damage Mechanism of Monocrystalline Si Under Mechanical Loading

Science.gov (United States)

Zhao, Qingliang; Zhang, Quanli; To, Suet; Guo, Bing

2017-03-01

Single-point diamond scratching and nanoindentation on monocrystalline silicon wafer were performed to investigate the surface damage mechanism of Si under the contact loading. The results showed that three typical stages of material removal appeared during dynamic scratching, and a chemical reaction of Si with the diamond indenter and oxygen occurred under the high temperature. In addition, the Raman spectra of the various points in the scratching groove indicated that the Si-I to β-Sn structure (Si-II) and the following β-Sn structure (Si-II) to amorphous Si transformation appeared under the rapid loading/unloading condition of the diamond grit, and the volume change induced by the phase transformation resulted in a critical depth (ductile-brittle transition) of cut (˜60 nm ± 15 nm) much lower than the theoretical calculated results (˜387 nm). Moreover, it also led to abnormal load-displacement curves in the nanoindentation tests, resulting in the appearance of elbow and pop-out effects (˜270 nm at 20 s, 50 mN), which were highly dependent on the loading/unloading conditions. In summary, phase transformation of Si promoted surface deformation and fracture under both static and dynamic mechanical loading.

Mechanical properties of cork under contact stresses

International Nuclear Information System (INIS)

Parralejo, A. D.; Guiberteau, F.; Fortes, M. A.; Rosa, M. E.

2001-01-01

In this work our interest is focussed on the mechanical behaviour of natural cork under contact stresses. Many of the applications of this curious material are related with its mechanical response under such a stress field, however this topic has not been still sufficiently considered in the scientific literature. For this purpose, we proposed the use of Hertzian indentation tests. By using this mythology we have investigated the cork structure influence on the corresponding mechanical properties. Our results reveal a clear mechanical anisotropy effect. Moreover, the elastic modulus corresponding to specific directions have been estimated. Several are the main advantages of this specific test mythology versus traditional uniaxial compression tests, specially simplicity and local character. (Author) 9 refs

The antimicrobial propeptide hCAP-18 plasma levels in neutropenia of various aetiologies

DEFF Research Database (Denmark)

Ye, Ying; Carlsson, Göran; Karlsson-Sjöberg, Jenny M T

2015-01-01

The underlying cause of neutropenia may be difficult to determine due to similar clinical presentation in many neutropenic conditions. The neutrophil protein hCAP-18 (pro-LL-37) is a major component of neutrophil secondary granules and in this prospective study we assessed the use of hCAP-18 levels...... in blood plasma for differential diagnosis of neutropenic patients (n = 133) of various aetiologies. Plasma levels of hCAP-18 were determined using immunoblot and ELISA. Patients with severe congenital neutropenia (n = 23) presented with the lowest levels of plasma hCAP-18 and differential diagnostic...... diagnostic value in differential diagnosis of chronic neutropenia. Neutropenic patients with Shwachman-Diamond syndrome, Barth syndrome, Cohen syndrome, acute myeloid leukaemia and specific granule deficiency presented with reduced plasma hCAP-18 levels as well. The blood plasma level of hCAP-18 was thus low...

Perspectives on the Aetiology of ODD and CD: A Grounded Theory Approach

Science.gov (United States)

McFarland, Patrick; Sanders, James; Hagen, Bradley

2016-01-01

Antisocial disorders, such as oppositional defiant disorder (ODD) and conduct disorder (CD), are common reasons for youth to be seen for clinical intervention. The intent of this constructivist grounded theory study was to evaluate clinicians' perspectives on the aetiology of antisocial disorders. Six professionals from various professional…

Aetiology, imaging and treatment of medial tibial stress syndrome

OpenAIRE

Moen, M.H.

2012-01-01

The work contained is this thesis discusses aetiology, imaging and treatment of a common leg injury: medial tibial stress syndrome (MTSS). Although a common injury, the number of scientific articles on this topic is relatively low as is explained in chapter 1. This chapter also highlights that the most probable cause of MTSS is bone overload and not traction induced periostitis. In chapter 2 a review of the literature on MTSS is provided until 2009. Chapters 3 and 4 discuss different common a...

Mechanisms of obesity in Prader-Willi syndrome.

Science.gov (United States)

Khan, M J; Gerasimidis, K; Edwards, C A; Shaikh, M G

2018-01-01

Obesity is the most common cause of metabolic complications and poor quality of life in Prader-Willi syndrome (PWS). Hyperphagia and obesity develop after an initial phase of poor feeding and failure to thrive. Several mechanisms for the aetiology of obesity in PWS are proposed, which include disruption in hypothalamic pathways of satiety control resulting in hyperphagia, aberration in hormones regulating food intake, reduced energy expenditure because of hypotonia and altered behaviour with features of autism spectrum disorder. Profound muscular hypotonia prevents PWS patients from becoming physically active, causing reduced muscle movements and hence reduced energy expenditure. In a quest for the aetiology of obesity, recent evidence has focused on several appetite-regulating hormones, growth hormone, thyroid hormones and plasma adipocytokines. However, despite advancement in understanding of the genetic basis of PWS, there are contradictory data on the role of satiety hormones in hyperphagia and data regarding dietary intake are limited. Mechanistic studies on the aetiology of obesity and its relationship with disease pathogenesis in PWS are required. . In this review, we focused on the available evidence regarding mechanisms of obesity and potential new areas that could be explored to help unravel obesity pathogenesis in PWS. © 2016 World Obesity Federation.

Frozen shoulder contracture syndrome - Aetiology, diagnosis and management.

Science.gov (United States)

Lewis, Jeremy

2015-02-01

Frozen shoulder is a poorly understood condition that typically involves substantial pain, movement restriction, and considerable morbidity. Although function improves overtime, full and pain free range, may not be restored in everyone. Frozen shoulder is also known as adhesive capsulitis, however the evidence for capsular adhesions is refuted and arguably, this term should be abandoned. The aim of this Masterclass is to synthesise evidence to provide a framework for assessment and management for Frozen Shoulder. Although used in the treatment of this condition, manipulation under anaesthetic has been associated with joint damage and may be no more effective than physiotherapy. Capsular release is another surgical procedure that is supported by expert opinion and published case series, but currently high quality research is not available. Recommendations that supervised neglect is preferable to physiotherapy have been based on a quasi-experimental study associated with a high risk of bias. Physiotherapists in the United Kingdom have developed dedicated care pathways that provide; assessment, referral for imaging, education, health screening, ultrasound guided corticosteroid and hydro-distension injections, embedded within physiotherapy rehabilitation. The entire pathway is provided by physiotherapists and evidence exists to support each stage of the pathway. Substantial on-going research is required to better understand; epidemiology, patho-aetiology, assessment, best management, health economics, patient satisfaction and if possible prevention. Copyright © 2014 Elsevier Ltd. All rights reserved.

aetiological agents of ear discharge: a two year re- view in a ...

African Journals Online (AJOL)

2014-06-01

Jun 1, 2014 ... SUMMARY. Background: The discharging ear is a common presentation in medical practice affecting all age groups but primarily children. This study shows the current aetiological causes of ear discharge and their antibiograms, data which would guide empirical treat- ment of ear infections, and also form ...

The opposite end of the attention deficit hyperactivity disorder continuum: genetic and environmental aetiologies of extremely low ADHD traits.

Science.gov (United States)

Greven, Corina U; Merwood, Andrew; van der Meer, Jolanda M J; Haworth, Claire M A; Rommelse, Nanda; Buitelaar, Jan K

2016-04-01

Although attention deficit hyperactivity disorder (ADHD) is thought to reflect a continuously distributed quantitative trait, it is assessed through binary diagnosis or skewed measures biased towards its high, symptomatic extreme. A growing trend is to study the positive tail of normally distributed traits, a promising avenue, for example, to study high intelligence to increase power for gene-hunting for intelligence. However, the emergence of such a 'positive genetics' model has been tempered for ADHD due to poor phenotypic resolution at the low extreme. Overcoming this methodological limitation, we conduct the first study to assess the aetiologies of low extreme ADHD traits. In a population-representative sample of 2,143 twins, the Strength and Weaknesses of ADHD Symptoms and Normal behaviour (SWAN) questionnaire was used to assess ADHD traits on a continuum from low to high. Aetiological influences on extreme ADHD traits were estimated using DeFries-Fulker extremes analysis. ADHD traits were related to behavioural, cognitive and home environmental outcomes using regression. Low extreme ADHD traits were significantly influenced by shared environmental factors (23-35%) but were not significantly heritable. In contrast, high-extreme ADHD traits showed significant heritability (39-51%) but no shared environmental influences. Compared to individuals with high extreme or with average levels of ADHD traits, individuals with low extreme ADHD traits showed fewer internalizing and externalizing behaviour problems, better cognitive performance and more positive behaviours and positive home environmental outcomes. Shared environmental influences on low extreme ADHD traits may reflect passive gene-environment correlation, which arises because parents provide environments as well as passing on genes. Studying the low extreme opens new avenues to study mechanisms underlying previously neglected positive behaviours. This is different from the current deficit-based model of

Clinical presentation and aetiologies of acute or complicated headache among HIV-seropositive patients in a Ugandan clinic.

Science.gov (United States)

Katwere, Michael; Kambugu, Andrew; Piloya, Theresa; Wong, Matthew; Hendel-Paterson, Brett; Sande, Merle A; Ronald, Allan; Katabira, Elly; Were, Edward M; Menten, Joris; Colebunders, Robert

2009-09-19

We set out to define the relative prevalence and common presentations of the various aetiologies of headache within an ambulant HIV-seropositive adult population in Kampala, Uganda. We conducted a prospective study of adult HIV-1-seropositive ambulatory patients consecutively presenting with new onset headaches. Patients were classified as focal-febrile, focal-afebrile, non-focal-febrile or non-focal-afebrile, depending on presence or absence of fever and localizing neurological signs. Further management followed along a pre-defined diagnostic algorithm to an endpoint of a diagnosis. We assessed outcomes during four months of follow up. One hundred and eighty patients were enrolled (72% women). Most subjects presented at WHO clinical stages III and IV of HIV disease, with a median Karnofsky performance rating of 70% (IQR 60-80).The most common diagnoses were cryptococcal meningitis (28%, n = 50) and bacterial sinusitis (31%, n = 56). Less frequent diagnoses included cerebral toxoplasmosis (4%, n = 7), and tuberculous meningitis (4%, n = 7). Thirty-two (18%) had other diagnoses (malaria, bacteraemia, etc.). No aetiology could be elucidated in 28 persons (15%). Overall mortality was 13.3% (24 of 180) after four months of follow up. Those without an established headache aetiology had good clinical outcomes, with only one death (4% mortality), and 86% were ambulatory at four months. In an African HIV-infected ambulatory population presenting with new onset headache, aetiology was found in at least 70%. Cryptococcal meningitis and sinusitis accounted for more than half of the cases.

Giant panda׳s tooth enamel: Structure, mechanical behavior and toughening mechanisms under indentation.

Science.gov (United States)

Weng, Z Y; Liu, Z Q; Ritchie, R O; Jiao, D; Li, D S; Wu, H L; Deng, L H; Zhang, Z F

2016-12-01

The giant panda׳s teeth possess remarkable load-bearing capacity and damage resistance for masticating bamboos. In this study, the hierarchical structure and mechanical behavior of the giant panda׳s tooth enamel were investigated under indentation. The effects of loading orientation and location on mechanical properties of the enamel were clarified and the evolution of damage in the enamel under increasing load evaluated. The nature of the damage, both at and beneath the indentation surfaces, and the underlying toughening mechanisms were explored. Indentation cracks invariably were seen to propagate along the internal interfaces, specifically the sheaths between enamel rods, and multiple extrinsic toughening mechanisms, e.g., crack deflection/twisting and uncracked-ligament bridging, were active to shield the tips of cracks from the applied stress. The giant panda׳s tooth enamel is analogous to human enamel in its mechanical properties, yet it has superior hardness and Young׳s modulus but inferior toughness as compared to the bamboo that pandas primarily feed on, highlighting the critical roles of the integration of underlying tissues in the entire tooth and the highly hydrated state of bamboo foods. Our objective is that this study can aid the understanding of the structure-mechanical property relations in the tooth enamel of mammals and further provide some insight on the food habits of the giant pandas. Copyright © 2016 Elsevier Ltd. All rights reserved.

A STUDY ON CLINICAL AND AETIOLOGICAL PROFILE OF HYPOKALAEMIC PARALYSIS IN A TERTIARY CARE HOSPITAL

Directory of Open Access Journals (Sweden)

Kekathi Vidyasagar

2016-08-01

Full Text Available BACKGROUND Hypokalaemic periodic paralysis is a rare disorder characterised by transient attacks of flaccid paralysis of varying intensity and frequency. Although mostly familial in aetiology, several sporadic cases with different causes have been reported. There are two groups of disorders predominantly that causes hypokalaemic paralysis. One group is due to transcellular shift of potassium and other is due to loss of potassium from body either through GI tract or through renal system. MATERIAL AND METHODS Here we report a study on the clinical and aetiological profile of 30 cases of hypokalaemic paralysis admitted in our institution between January 2014 to January 2016. RESULTS The aetiological workup of all the patients was done which revealed thyrotoxic periodic paralysis as the major cause in 12 of 30 patients. Three rare causes of hypokalaemia have been diagnosed which included Bartter’s syndrome, Mixed Connective tissue disorder, Sjogren’s syndrome. Vomiting and diarrhoea was seen in 12 of 30 patients. CONCLUSION Hypokalaemic periodic paralysis is a heterogenous group of disorder. A significant number of patients had thyroid disorders mostly in the form of thyrotoxicosis, non-renal and renal loss of potassium like diarrhoea and vomiting. Early recognition and prompt management of these conditions is essential to prevent residual deformity and further attacks in future.

http://www.bioline.org.br/js 101 Aetiological Profile of Facial Nerve ...

African Journals Online (AJOL)

jen

Background: Facial nerve abnormalities represent a broad spectrum of lesions which are commonly seen by the otolaryngologist. The aim of this paper is to highlight the aetiologic profile of facial nerve palsy. Methods: A retrospective study of patients with facial nerve palsy seen in the Ear, Nose and Throat clinic for 5 years.

Paediatric retinal detachment: aetiology, characteristics and outcomes.

Science.gov (United States)

McElnea, Elizabeth; Stephenson, Kirk; Gilmore, Sarah; O'Keefe, Michael; Keegan, David

2018-01-01

To provide contemporary data on the aetiology, clinical features and outcomes of paediatric retinal detachment. A retrospective review of all those under 16y who underwent surgical repair for retinal detachment at a single centre between the years 2008 and 2015 inclusive was performed. In each case the cause of retinal detachment, the type of detachment, the presence or absence of macular involvement, the number and form of reparative surgeries undertaken, and the surgical outcome achieved was recorded. Twenty-eight eyes of 24 patients, 15 (62.5%) of whom were male and 9 (37.5%) of whom were female, their mean age being 11.6y and range 2-16y developed retinal detachment over the eight year period studied. Trauma featured in the development of retinal detachment in 14 (50.0%) cases. Retinal detachment was associated with other ocular and/or systemic conditions in 11 (39.3%) cases. A mean of 3.0 procedures with a range of 1-9 procedures per patient were undertaken in the management of retinal detachment. Complex vitrectomy combined with scleral buckling or complex vitrectomy alone were those most frequently performed. Mean postoperative visual acuity was 1.2 logMAR with range 0.0-3.0 logMAR. In 22 of 26 (84.6%) cases which underwent surgical repair the retina was attached at last follow-up. Aggressive management of paediatric retinal detachment including re-operation increases the likelihood of anatomical success. In cases where the retinal detachment can be repaired by an external approach alone there is a more favourable visual outcome.

Peeling mechanism of tomato under infrared heating

Science.gov (United States)

Critical behaviors of peeling tomatoes using infrared heat are thermally induced peel loosening and subsequent cracking. However, the mechanism of peel loosening and cracking due to infrared heating remains unclear. This study aimed at investigating the mechanism of peeling tomatoes under infrared h...

A review of the current literature on aetiology and measurement methods of halitosis.

NARCIS (Netherlands)

Broek, A.M. van den; Feenstra, L.; Baat, C. de

2007-01-01

OBJECTIVES: This work reviews the current knowledge of aetiology and measurement methods of halitosis. DATA: Halitosis is an unpleasant or offensive odour emanating from the breath. The condition is multifactorial and may involve both oral and non-oral conditions. SOURCES: A private, monthly with

The aetiology of rickets-like lower limb deformities in Malawian children.

Science.gov (United States)

Braithwaite, V S; Freeman, R; Greenwood, C L; Summers, D M; Nigdikar, S; Lavy, C B D; Offiah, A C; Bishop, N J; Cashman, J; Prentice, A

2016-07-01

Debilitating rickets-like lower limb deformities are common in children throughout the world, particularly in Malawi, Africa where the causes are unknown. We have identified that Blount disease and calcium deficiency rickets are the likely causes of these deformities and propose calcium supplementation as a potential treatment of Malawian rickets. Surgical correction of rickets-like lower limb deformities is the most common paediatric operation performed at Beit Cure Orthopaedic Hospital, Malawi. The aim of this study was to investigate the aetiology of these deformities. Children with a tibio-femoral angle of deformity >20° were enrolled (n = 42, 3.0-15.0 years). Anthropometric and early life and well-being data were collected. Early morning serum and urine samples were collected on the morning of the operation for markers of calcium and phosphate homeostasis. Knee radiographs were obtained, and the children were diagnosed with either Blount (BD, n = 22) or evidence of rickets disease (RD, n = 20). As BD is a mechanical rather than metabolic disease, BD were assumed to be biochemically representative of the local population and thus used as a local reference for RD. There were no differences in anthropometry or early life experiences between BD and RD. Parathyroid hormone (PTH), 1,25-dihydroxyvitamin D, total alkaline phosphatase and urinary phosphate were significantly higher and serum phosphate, 25-hydroxyvitamin D (25OHD) and tubular maximal reabsorption of phosphate significantly lower in RD than BD. There was no difference in serum calcium, fibroblast growth factor 23 or markers of iron status between groups. All children had 25OHD > 25 nmol/L. Vitamin D deficiency is not implicated in the aetiology of RD or BD in Malawian children. The cause of RD in Malawi is likely to be dietary calcium deficiency leading to elevated PTH resulting in increased losses of phosphate from the bone and glomerular filtrate. The causes of BD remain unclear

Does the sun play a role in the aetiology of malignant melanoma ...

African Journals Online (AJOL)

The role of the sun in the aetiology of malignant melanoma is controversial. In 1992 Schuster1 wrote provocatively, 'Despite the lack of evidence of a causal link between sun exposure and melanoma, fear has been used shamelessly to frighten people out of the sun and into pigmented lesion clinics.' He claimed that the ...

Aetiology and incidence of maxillofacial trauma in Amsterdam: a retrospective analysis of 579 patients

NARCIS (Netherlands)

van den Bergh, B.; Karagozoglu, K.H.; Heymans, M.W.; Forouzanfar, T.

2012-01-01

Introduction The incidence of maxillofacial fractures varies widely between different countries. The large variability in reported incidence and aetiology is due to a variety of contributing factors, including environmental, cultural and socioeconomic factors. This retrospective report presents a

Aetiology and incidence of maxillofacial trauma in Amsterdam: a retrospective analysis of 579 patients

NARCIS (Netherlands)

van den Bergh, B.; Karagozoglu, K.H.; Heijmans, M.W.; Forouzanfar, T.

2012-01-01

Introduction: The incidence of maxillofacial fractures varies widely between different countries. The large variability in reported incidence and aetiology is due to a variety of contributing factors, including environmental, cultural and socioeconomic factors. This retrospective report presents a

Deciphering the Cognitive and Neural Mechanisms Underlying ...

International Development Research Centre (IDRC) Digital Library (Canada)

Deciphering the Cognitive and Neural Mechanisms Underlying Auditory Learning. This project seeks to understand the brain mechanisms necessary for people to learn to perceive sounds. Neural circuits and learning. The research team will test people with and without musical training to evaluate their capacity to learn ...

AETIOLOGY OF ACQUIRED LOWER MOTOR NEURON TYPE OF FACIAL NERVE PARALYSIS– A DESCRIPTIVE STUDY

Directory of Open Access Journals (Sweden)

Arya Devi Karangat

2018-02-01

Full Text Available BACKGROUND This study was conducted to evaluate the various aetiologies of acquired lower motor neuron type of facial nerve paralysis, assessment of severity of lesion and outcome through follow up. 47 patients between 15-75 years were studied. MATERIALS AND METHODS All patients with acquired LMN facial paralysis who presented to our department were included in the study. They were evaluated with history, clinical examination and investigations. They were treated and followed up for a period of 6 months. RESULTS The most common aetiology identified for facial palsy was trauma which was non-iatrogenic. The anatomic level which predominated in our patients was infrastapedial. Maximum number of patients presented with grade 4 facial palsy. CONCLUSION Non- iatrogenic trauma was the most common cause among the patients studied and follow up of these patients had a good recovery of 60%.

Gas Bubble Dynamics under Mechanical Vibrations

Science.gov (United States)

Mohagheghian, Shahrouz; Elbing, Brian

2017-11-01

The scientific community has a limited understanding of the bubble dynamics under mechanical oscillations due to over simplification of Navier-Stockes equation by neglecting the shear stress tensor and not accounting for body forces when calculating the acoustic radiation force. The current work experimental investigates bubble dynamics under mechanical vibration and resulting acoustic field by measuring the bubble size and velocity using high-speed imaging. The experimental setup consists of a custom-designed shaker table, cast acrylic bubble column, compressed air injection manifold and an optical imaging system. The mechanical vibrations resulted in accelerations between 0.25 to 10 times gravitational acceleration corresponding to frequency and amplitude range of 8 - 22Hz and 1 - 10mm respectively. Throughout testing the void fraction was limited to <5%. The bubble size is larger than resonance size and smaller than acoustic wavelength. The amplitude of acoustic pressure wave was estimated using the definition of Bjerknes force in combination with Rayleigh-Plesset equation. Physical behavior of the system was capture and classified. Bubble size, velocity as well as size and spatial distribution will be presented.

Genomic interrogation of mechanism(s) underlying cellular responses to toxicants

International Nuclear Information System (INIS)

Amin, Rupesh P.; Hamadeh, Hisham K.; Bushel, Pierre R.; Bennett, Lee; Afshari, Cynthia A.; Paules, Richard S.

2002-01-01

Assessment of the impact of xenobiotic exposure on human health and disease progression is complex. Knowledge of mode(s) of action, including mechanism(s) contributing to toxicity and disease progression, is valuable for evaluating compounds. Toxicogenomics, the subdiscipline which merges genomics with toxicology, holds the promise to contributing significantly toward the goal of elucidating mechanism(s) by studying genome-wide effects of xenobiotics. Global gene expression profiling, revolutionized by microarray technology and a crucial aspect of a toxicogenomic study, allows measuring transcriptional modulation of thousands of genes following exposure to a xenobiotic. We use our results from previous studies on compounds representing two different classes of xenobiotics (barbiturate and peroxisome proliferator) to discuss the application of computational approaches for analyzing microarray data to elucidate mechanism(s) underlying cellular responses to toxicants. In particular, our laboratory demonstrated that chemical-specific patterns of gene expression can be revealed using cDNA microarrays. Transcript profiling provides discrimination between classes of toxicants, as well as, genome-wide insight into mechanism(s) of toxicity and disease progression. Ultimately, the expectation is that novel approaches for predicting xenobiotic toxicity in humans will emerge from such information

Oxytocin receptor (OXTR) does not play a major role in the aetiology of autism: genetic and molecular studies.

Science.gov (United States)

Tansey, Katherine E; Brookes, Keeley J; Hill, Matthew J; Cochrane, Lynne E; Gill, Michael; Skuse, David; Correia, Catarina; Vicente, Astrid; Kent, Lindsey; Gallagher, Louise; Anney, Richard J L

2010-05-03

Oxytocin (OXT) has been hypothesized to play a role in aetiology of autism based on a demonstrated involvement in the regulation of social behaviours. It is postulated that OXT reduces activation of the amygdala, inhibiting social anxiety, indicating a neural mechanism for the effects of OXT in social cognition. Genetic variation at the oxytocin receptor gene (OXTR) has been reported to be associated with autism. We examined 18 SNPs at the OXTR gene for association in three independent autism samples from Ireland, Portugal and the United Kingdom. We investigated cis-acting genetic effects on OXTR expression in lymphocytes and amygdala region of the brain using an allelic expression imbalance (AEI) assay and by investigating the correlation between RNA levels and genotype in the amygdala region. No marker survived multiple correction for association with autism in any sample or in a combined sample (n=436). Results from the AEI assay performed in the lymphoblast cell lines highlighted two SNPs associated with relative allelic abundance in OXTR (rs237897 and rs237895). Two SNPs were found to be effecting cis-acting variation through AEI in the amygdala. One was weakly correlated with total gene expression (rs13316193) and the other was highlighted in the lymphoblast cell lines (rs237895). Data presented here does not support the role of common genetic variation in OXTR in the aetiology of autism spectrum disorders in Caucasian samples. 2010 Elsevier Ireland Ltd. All rights reserved.

Paediatric retinal detachment: aetiology, characteristics and outcomes

Directory of Open Access Journals (Sweden)

Elizabeth McElnea

2018-02-01

Full Text Available AIM: To provide contemporary data on the aetiology, clinical features and outcomes of paediatric retinal detachment. METHODS: A retrospective review of all those under 16y who underwent surgical repair for retinal detachment at a single centre between the years 2008 and 2015 inclusive was performed. In each case the cause of retinal detachment, the type of detachment, the presence or absence of macular involvement, the number and form of reparative surgeries undertaken, and the surgical outcome achieved was recorded. RESULTS: Twenty-eight eyes of 24 patients, 15 (62.5% of whom were male and 9 (37.5% of whom were female, their mean age being 11.6y and range 2-16y developed retinal detachment over the eight year period studied. Trauma featured in the development of retinal detachment in 14 (50.0% cases. Retinal detachment was associated with other ocular and/or systemic conditions in 11 (39.3% cases. A mean of 3.0 procedures with a range of 1-9 procedures per patient were undertaken in the management of retinal detachment. Complex vitrectomy combined with scleral buckling or complex vitrectomy alone were those most frequently performed. Mean postoperative visual acuity was 1.2 logMAR with range 0.0-3.0 logMAR. In 22 of 26 (84.6% cases which underwent surgical repair the retina was attached at last follow-up. CONCLUSION: Aggressive management of paediatric retinal detachment including re-operation increases the likelihood of anatomical success. In cases where the retinal detachment can be repaired by an external approach alone there is a more favourable visual outcome.

Predicting the characteristics of the aetiological agent for Kawasaki disease from other paediatric infectious diseases in Japan.

Science.gov (United States)

Nagao, Y; Urabe, C; Nakamura, H; Hatano, N

2016-02-01

Although Kawasaki disease (KD), which was first reported in the 1960s, is assumed to be infectious, its aetiological agent(s) remains unknown. We compared the geographical distribution of the force of infection and the super-annual periodicity of KD and seven other paediatric infectious diseases in Japan. The geographical distribution of the force of infection, which was estimated as the inverse of the mean patient age, was similar in KD and other paediatric viral infections. This similarity was due to the fact that the force of infection was determined largely by the total fertility rate. This finding suggests that KD shares a transmission route, i.e. sibling-to-sibling infection, with other paediatric infections. The super-annual periodicity, which is positively associated with the sum of an infectious disease's incubation period and infectious period, was much longer for KD and exanthema subitum than other paediatric infectious diseases. The virus for exanthema subitum is known to persist across the host's lifespan, which suggests that the aetiological agent for KD may also be capable of persistent infection. Taken together, these findings suggest that the aetiological agent for KD is transmitted through close contact and persists asymptomatically in most hosts.

The aetiology of acute and chronic pancreatitis over time in a hospital in Copenhagen

DEFF Research Database (Denmark)

Nøjgaard, Camilla; Bendtsen, Flemming; Matzen, Peter

2010-01-01

: Gallstone disease significantly (p = 0.04) increased as the cause of acute pancreatitis over the 22-year period, while alcohol remained the major cause of chronic pancreatitis. The validity of the diagnoses for patients with acute pancreatitis varied between 51% and 73%, and for chronic pancreatitis between......INTRODUCTION: The change in aetiology over time of acute and chronic pancreatitis has been sparsely described, as has also the validity of the diagnostic codes. The aim of the study was 1) to clarify whether the aetiology of acute and chronic pancreatitis changed during the period 1983-2005, and 2......) to validate the diagnostic codes over time for acute and chronic pancreatitis registered in the Danish National Patient Registry (NPR) in the same period. MATERIAL AND METHODS: All admissions at Hvidovre Hospital coded in the NPR in 1983, 1994 and 2005 with a diagnosis of either acute or chronic pancreatitis...

BNP but Not s-cTnln is associated with cardioembolic aetiology and predicts short and long term prognosis after cerebrovascular events.

Directory of Open Access Journals (Sweden)

Nicole Nigro

Full Text Available We analyzed the prognostic value of b-type natriuretic peptide (BNP and sensitive cardiac Troponin (s-cTnI in patients with ischemic stroke or transient ischemic attack (TIA and their significance in predicting stroke aetiology.In a prospectively enrolled cohort we measured BNP and s-cTnI levels upon admission. Primary endpoints were mortality, unfavorable functional outcome and stroke recurrence after 90 days and after 12 months. Secondary endpoint was cardioembolic aetiology.In 441 patients BNP but not s-cTnI remained an independent predictor for death with an adjusted HR of 1.2 (95% CI 1.1-1.4 after 90 days and 1.2 (95% CI 1.0-1.3 after one year. The comparison of the Area under Receiver Operating Characteristic (AUROC of model A (age, NIHSS and model B (age, NIHSS, BNP showed an improvement in the prediction of mortality (0.85 (95% CI 0.79-0.90 vs. 0.86 (95% CI 0.81-0.92, Log Rank p = 0.004. Furthermore the category free net reclassification improvement (cfNRI when adding BNP to the multivariate model was 57.5%, p<0.0001. For the prediction of functional outcome or stroke recurrence both markers provided no incremental value. Adding BNP to a model including age, atrial fibrillation and heart failure lead to a higher discriminatory accuracy for identification of cardioembolic stroke than the model without BNP (AUC 0.75 (95% CI 0.70-0.80 vs. AUC 0.79, (95% CI 0.75-0.84, p = 0.008.BNP is an independent prognostic maker for overall mortality in patients with ischemic stroke or TIA and may improve the diagnostic accuracy to identify cardioembolic aetiology.ClinicalTrials.gov NCT00390962.

Levels of uric acid in erectile dysfunction of different aetiology.

Science.gov (United States)

Barassi, Alessandra; Corsi Romanelli, Massimiliano Marco; Pezzilli, Raffaele; Dozio, Elena; Damele, Clara Anna Linda; Vaccalluzzo, Liborio; Di Dario, Marco; Goi, Giancarlo; Papini, Nadia; Massaccesi, Luca; Colpi, Giovanni Maria; Melzi d'Eril, Gian Vico

2018-01-12

Erectile dysfunction is a common disease characterized by endothelial dysfunction. The aetiology of ED is often multifactorial but evidence is being accumulated in favor of the proper function of the vascular endothelium that is essential to achieving and maintaining penile erection. Uric acid itself causes endothelial dysfunction via decreased nitric oxide production. This study aims to evaluate the serum uric acid (SUA) levels in 180 ED patients, diagnosed with the International Index of Erectile Function-5 (IIEF-5) and 30 non-ED control. Serum uric acid was analyzed with a commercially available kit using ModularEVO (Roche, Monza, Italy). Within-assay and between-assay variations were 3.0% and 6.0%, respectively. Out of the ED patients, 85 were classified as arteriogenic (A-ED) and 95 as non-arteriogenic (NA-ED) with penile-echo-color-Doppler. Uric acid levels (median and range in mg/dL) in A-ED patients (5.8, 4.3-7.5) were significantly higher (p uric acid levels in patients with mild A-ED (IIEF-5 16-20) and severe/complete A-ED (IIEF-5 ≤ 10) that were 5.4 (range 4.3-6.5) mg/dL and 6.8 (range 6.4-7.2) mg/dL, respectively. There was no difference between the levels of uric acid in patients with different degree of NA-ED. Our findings reveal that SUA is a marker of ED but only of ED of arteriogenic aetiology.

The contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases

DEFF Research Database (Denmark)

Thomsen, Simon F

2015-01-01

The prevalence of asthma and other atopic diseases has increased markedly during the past decades and the reasons for this are not fully understood. Asthma is still increasing in many parts of the world, notably in developing countries, and this emphasizes the importance of continuing research...... aimed at studying the aetiological factors of the disease and the causes of its increase in prevalence. Twin studies enable investigations into the genetic and environmental causes of individual variation in multifactorial diseases such as asthma. Thorough insight into these causes is important...... as this will ultimately guide the development of preventive strategies and targeted therapies. This review explores the contribution of twin studies to the understanding of the aetiology of asthma and atopic diseases....

Additional perspectives on chronic kidney disease of unknown aetiology (CKDu) in Sri Lanka--lessons learned from the WHO CKDu population prevalence study.

Science.gov (United States)

Redmon, Jennifer Hoponick; Elledge, Myles F; Womack, Donna S; Wickremashinghe, Rajitha; Wanigasuriya, Kamani P; Peiris-John, Roshini J; Lunyera, Joseph; Smith, Kristin; Raymer, James H; Levine, Keith E

2014-07-28

The recent emergence of an apparently new form of chronic kidney disease of unknown aetiology (CKDu) has become a serious public health crisis in Sri Lanka. CKDu is slowly progressive, irreversible, and asymptomatic until late stages, and is not attributable to hypertension, diabetes, or other known aetiologies. In response to the scope and severity of the emerging CKDu health crisis, the Sri Lanka Ministry of Health and the World Health Organization initiated a collaborative research project from 2009 through 2012 to investigate CKDu prevalence and aetiology. The objective of this paper is to discuss the recently published findings of this investigation and present additional considerations and recommendations that may enhance subsequent investigations designed to identify and understand CKDu risk factors in Sri Lanka or other countries.

South African Muslim Faith Healers perceptions of mental illness: understanding, aetiology and treatment.

Science.gov (United States)

Ally, Yaseen; Laher, Sumaya

2008-03-01

The important role that religious beliefs may have on perceptions of mental illness cannot be ignored. Many religions including Islam advocate witchcraft and spirit possession--all of which are thought to influence the behaviour of a person so as to resemble that of a mentally ill individual. Thus this research explored Muslim Faith Healers perceptions of mental and spiritual illness in terms of their understanding of the distinctions between the two, the aetiologies and the treatments thereof. Six Muslim Healers in the Johannesburg community were interviewed and thematic content analysis was used to analyse the data. From the results it is clear that the faith healers were aware of the distinction between mental and spiritual illnesses. It was also apparent that Islam has a clear taxonomy that distinguishes illness and the causes thereof. Treatments are then advised accordingly. Thus this paper argues that the predominant Western view of the aetiology and understanding of mental illness needs to acknowledge the various culturally inclined taxonomies of mental illness so as to better understand and aid clients.

Masculinity and emotion in Mexican men's understandings of erectile dysfunction aetiology and treatment.

Science.gov (United States)

Wentzell, Emily

2014-01-01

This paper investigates the role that emotions related to local gender norms play in urban Mexican men's understandings of erectile dysfunction (ED) aetiology and drug treatment by analysing semi-structured interviews with 28 male urology patients. Analysing narrative data from our interviews, the paper examines how these men drew differently from locally intelligible ways of understanding health and masculinity to develop context-specific understandings of causes and potential treatment outcomes. Study participants' feelings of success or failure in life areas relating to the performance of 'responsible' masculinity, especially work and romance, strongly influenced understandings of ED aetiology and goals for drug treatment. Those who felt successful at being men collaborated with loved ones to adopt purely biological understandings of ED causation, while those who expressed negative emotions about their performances of masculinity viewed these feelings, as well as the structural and interpersonal problems that caused them, as key causes and consequences of dysfunction. I discuss how these different emotional experiences led to different ways of using medication, and the relevance of these findings for clinical practice.

Natural history of severe eosinophilia with uncertain aetiology and proposals on a practical approach to its management.

Science.gov (United States)

Ang, A L; Wong, R X; Zhuang, Q Y; Linn, Y C

2012-08-01

Eosinophilia is commonly encountered during clinical practice. Some can be attributed to well-defined causes while others cannot. Optimal management of hypereosinophilia with unknown aetiology is uncertain as the natural history is not well described. We retrospectively studied patients with hypereosinophilia (>5 × 10(9)/L) and described the characteristics, natural history and treatment of those with eosinophilia of uncertain aetiology. There were 141 patients with hypereosinophilia: 87 with well-defined causes, 54 with uncertain aetiology. The latter was managed as hypereosinophilic syndrome (HES) (n = 5), idiopathic hypereosinophilia (IH) (n = 11), presumptive helminthic infection (n = 11) and reactive eosinophilia (n = 5), while 22 were insufficiently investigated and did not have definite working diagnoses. Their median age and peak eosinophil count were 64 (22 to 94) years and 10.0 (5.2-33.9) × 10(9)/L respectively. Forty-six per cent had symptoms attributable to eosinophilia, with the HES and insufficiently investigated groups having the highest (100%) and lowest (27%) percentages respectively. HES and IH patients were most extensively investigated. All 14 HES or IH patients who received steroids responded. All presumptive helminthic infection patients received mebendazole: nine responded, and two had unassessable responses. For the remaining patients, seven received steroids and all responded; one received mebendazole but defaulted; 19 were not treated: 11 resolved spontaneously. No non-HES patients developed eosinophilia-related organ dysfunction. No mortality was caused by hypereosinophilia. Patients with hypereosinophilia of uncertain aetiology can be empirically managed according to working diagnoses derived from history taking, examination and selective investigations. Most patients have benign short-term outcomes, but longer monitoring is required to assess long-term outcomes from untreated hypereosinophilia. © 2011 The Authors. Internal Medicine

Painful bladder syndrome/interstitial cystitis: Aetiology, evaluation and management

Directory of Open Access Journals (Sweden)

William Rourke

2014-06-01

Full Text Available Interstitial cystitis or bladder pain syndrome (BPS is often a chronic debilitating condition characterised by predominantly storage symptoms and associated frequently with pelvic pain that varies with bladder filling. The aetiology is uncertain as the condition occurs in the absence of a urinary tract infection or other obvious pathology. Resulting discomfort may vary and ranges from abdominal tenderness to intense bladder spasms. Diagnosis and management of this syndrome may be difficult and is often made by its typical cystoscopic features. This review discusses the diagnosis and management of interstitial cystitis according to the current available best evidence and advises a multimodal approach in its management.

Status epilepticus: Aetiology and D outcome in children

International Nuclear Information System (INIS)

Siddiqui, T.S.; Rehman, A.U.; Wazeer, M.S.

2008-01-01

Convulsing Status Epilepticus (CSE) is a common paediatric emergency especially under 24 months age group. Present study was done to know causes of Status Epilepticus (SE) and outcome during admission and at the time of discharge. A descriptive study in children 2 months to 15 years of age, admitted in Department of Paediatrics, Ayub Medical College, Abbottabad with first status epilepticus, was done to evaluate aetiology, complications and immediate outcome after relevant history, examination, laboratory tests. All information was recorded on Performa designed especially for this purpose. Study was conducted over 2 year period from November 2005 to November 2007. Total number of children admitted with SE was 125. Majority of SE episodes were related to acute febrile illnesses. Acute viral encephalitis was the common cause of SE especially in children younger than 24 months followed by febrile convulsions. Fifteen (12%) patients expired while neurological complications secondary to brain injury developed in 10(8%) cases. Mean seizure duration was 4.92+-9.18 hours in children with normal outcome, 5.93+-5.76 hours in children who died, and 12.85+-12.91 hours in children with abnormal neurological outcome at discharge (p>0.05). Correlation between age and duration of seizure was not significant (p>0.05). SE is a common paediatric emergency associated with high mortality and morbidity. In young children SE is commonly associated with acute viral encephalitis. Antiviral treatment should be started earlier in this group of young children after history, examination, laboratory tests along with appropriate management of SE. (author)

Status epilepticus: Aetiology and D outcome in children

Energy Technology Data Exchange (ETDEWEB)

Siddiqui, T S; Rehman, A U [Ayub Medical College, Abbottabad (Pakistan). Dept. of Paediatrics; Wazeer, M S [Saidu Group of Hospital, Swat (Pakistan). Dept. of Community Medicine

2008-07-15

Convulsing Status Epilepticus (CSE) is a common paediatric emergency especially under 24 months age group. Present study was done to know causes of Status Epilepticus (SE) and outcome during admission and at the time of discharge. A descriptive study in children 2 months to 15 years of age, admitted in Department of Paediatrics, Ayub Medical College, Abbottabad with first status epilepticus, was done to evaluate aetiology, complications and immediate outcome after relevant history, examination, laboratory tests. All information was recorded on Performa designed especially for this purpose. Study was conducted over 2 year period from November 2005 to November 2007. Total number of children admitted with SE was 125. Majority of SE episodes were related to acute febrile illnesses. Acute viral encephalitis was the common cause of SE especially in children younger than 24 months followed by febrile convulsions. Fifteen (12%) patients expired while neurological complications secondary to brain injury developed in 10(8%) cases. Mean seizure duration was 4.92+-9.18 hours in children with normal outcome, 5.93+-5.76 hours in children who died, and 12.85+-12.91 hours in children with abnormal neurological outcome at discharge (p>0.05). Correlation between age and duration of seizure was not significant (p>0.05). SE is a common paediatric emergency associated with high mortality and morbidity. In young children SE is commonly associated with acute viral encephalitis. Antiviral treatment should be started earlier in this group of young children after history, examination, laboratory tests along with appropriate management of SE. (author)

The aetiology of paediatric inflammatory vulvovaginitis.

Science.gov (United States)

Cuadros, Juan; Mazón, Ana; Martinez, Rocío; González, Pilar; Gil-Setas, Alberto; Flores, Uxua; Orden, Beatriz; Gómez-Herruz, Peña; Millan, Rosario

2004-02-01

Vulvovaginitis is the most common gynaecological problem in prepubertal girls and clear-cut data on the microbial aetiology of moderate to severe infections are lacking. Many microorganisms have been reported in several studies, but frequently the paediatrician does not know the pathogenic significance of an isolate reported in vaginal specimens of girls with vulvovaginitis. A multicentre study was performed, selecting 74 girls aged 2 to 12 years old with a clinical picture of vulvovaginitis and inflammatory cells on Gram stain. All the specimens were cultured following standard microbiological techniques and the paediatricians completed a questionnaire to highlight risk factors after interviewing the parents or tutors. The data were compared with those obtained in a control group of 11 girls without vulvovaginitis attending a clinic. Streptococcus pyogenesand Haemophilus spp.were isolated in 47 and 12 cases, respectively. Upper respiratory infection in the previous month ( Pvulvovaginitis in the previous year ( Pvulvovaginitis is mainly caused by pathogens of the upper respiratory tract and the most common risk factor for this infection is to have suffered an upper respiratory tract infection in the previous month.

Characteristics, aetiological spectrum and management of valvular heart disease in a Tunisian cardiovascular centre.

Science.gov (United States)

Triki, Faten; Jdidi, Jihen; Abid, Dorra; Tabbabi, Nada; Charfeddine, Selma; Ben Kahla, Sahar; Hentati, Mourad; Abid, Leila; Kammoun, Samir

Valvular heart diseases occur frequently in Tunisia, but no precise statistics are available. To analyse the characteristics of patients with abnormal valvular structure and function, and to identify the aetiological spectrum, treatment and outcomes of valvular heart disease in a single cardiovascular centre in Tunisia. This retrospective study included patients with abnormal valvular structure and function, who were screened by transthoracic echocardiography at a single cardiology department between January 2010 and December 2013. Data on baseline characteristics, potential aetiology, treatment strategies and discharge outcomes were collected from medical records. There were 959 patients with a significant valvular heart disease (mean age 53±17years; female/male ratio 0.57). Valvular heart disease was native in 77% of patients. Mitral stenosis was the most frequent lesion (44.1%), followed by multiple valve disease (22.3%). Rheumatic origin (66.6%) was the most frequent aetiology, followed by degenerative (17.2%) or ischaemic (8.1%) causes, endocarditis (1.4%) and congenital (0.9%) causes. Native valve disease was severe in 589 patients (61.4%). Percutaneous mitral balloon valvuloplasty was performed in 36.9% of patients with mitral stenosis. Among patients with severe valvular heart disease, surgical treatment was indicated for 446 (75.7%) patients. Only 161 (36.1%) patients were finally operated. Postoperative mortality was 13.6% for all valvular heart diseases. This retrospective study has shown that the main cause of valvular heart disease in Tunisia is rheumatic fever. Mitral stenosis and multiple valve disease are the most frequent valvular heart diseases in Tunisia. Percutaneous mitral balloon valvuloplasty and prosthetic valve replacement are the preferred treatment methods for valvular heart disease. Copyright © 2016. Published by Elsevier Masson SAS.

New data on aetiology of nodular gill disease in rainbow trout, Oncorhynchus mykiss

Czech Academy of Sciences Publication Activity Database

Dyková, Iva; Kostka, Martin; Wortberg, F.; Nardy, E.; Pecková, Hana

2010-01-01

Roč. 57, č. 3 (2010), s. 157-163 ISSN 0015-5683 R&D Projects: GA ČR GA524/09/0137; GA MŠk LC522 Institutional research plan: CEZ:AV0Z60220518 Keywords : nodular gill disease * aetiological study * amoebae * Naegleria sp. * fish diseases * aquaculture * Oncorhynchus mykiss Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 1.533, year: 2010

Aetiological diagnosis of male sex ambiguity: a collaborative study.

Science.gov (United States)

Morel, Yves; Rey, Rodolfo; Teinturier, Cécile; Nicolino, Marc; Michel-Calemard, Laurence; Mowszowicz, Irène; Jaubert, Francis; Fellous, Marc; Chaussain, Jean-Louis; Chatelain, Pierre; David, Michel; Nihoul-Fékété, Claire; Forest, Maguelone G; Josso, Nathalie

2002-01-01

A collaborative study, supported by the Biomed2 Programme of the European Community, was initiated to optimise the aetiological diagnosis in genetic or gonadal males with intersex disorders, a total of 67 patients with external sexual ambiguity, testicular tissue and/or a XY karyotype. In patients with gonadal dysgenesis or true hermaphroditism, the incidence of vaginal development was 100%, a uterus was present in 60%; uni or bilateral cryptorchidism was seen in nearly all cases of testicular dysgenesis (99%) but in only 57% of true hermaphrodites. Mean serum levels of anti-mullerian hormone and of serum testosterone response to chorionic gonadotropin stimulation were significantly decreased in both conditions, by comparison with patients with unexplained male pseudohermaphroditism or partial androgen insensitivity (PAIS). Mutations in the androgen receptor, 90% within exons 2-8, were detected in patients with PAIS. Clinically, a vaginal pouch was present in 90%, cryptorchidism in 36%. In 52% of cases, no diagnosis could be reached, despite an exhaustive clinical and laboratory work-up, including routine sequencing of exons 2-8 of the androgen receptor. By comparison with PAIS, unexplained male pseudohermaphroditism was characterised by a lower incidence of vaginal pouch (55%) and cryptorchidism (22%) but a high incidence of prematurity/intrauterine growth retardation (30%) or mild malformations (14%). reaching an aetiological diagnosis in cases of male intersex is difficult because of the variability of individual cases. Hormonal tests may help to discriminate between partial androgen insensitivity and gonadal dysgenesis/true hermaphroditism but are of less use for differentiating from unexplained male pseudohermaphroditism. Sequencing of exons 2-8 of the androgen receptor after study of testosterone precursors following human chorionic gonadotrophin stimulation is recommended when gonadal dysgenesis and true hermaphroditism can be excluded.

Aetiology of male urethritis in patients recruited from a population with a high HIV prevalence.

NARCIS (Netherlands)

Sturm, P.D.J.; Moodley, P.; Khan, N.; Ebrahim, S.; Govender, K.; Connolly, C.E.; Sturm, A.W.

2004-01-01

The aetiology of urethritis, the significance of potential pathogens and the relation of urethritis to HIV infection were determined in 335 men (cases) with and 100 men (controls) without urethral symptoms. Urethral swab specimens were tested for different organisms by PCR or by culture for

Eisenmenger syndrome and idiopathic pulmonary arterial hypertension: do parenchymal lung changes reflect aetiology?

International Nuclear Information System (INIS)

Griffin, N.; Allen, D.; Wort, J.; Rubens, M.; Padley, S.

2007-01-01

Aim: To document the pulmonary vascular changes on thin-section computed tomography (CT) in patients with Eisenmenger syndrome and idiopathic pulmonary arterial hypertension, and to determine whether there is any correlation with pulmonary arterial pressures or the aetiology of pulmonary hypertension. Material and methods: From the National Pulmonary Hypertension Database, we identified eight patients with idiopathic pulmonary arterial hypertension and 20 patients with Eisenmenger syndrome (secondary to a ventriculoseptal defect) who had also undergone contrast-enhanced thin-section CT. CT studies were reviewed for the presence of centrilobular nodules, mosaicism, neovascularity, and bronchial artery hypertrophy. Haemodynamic data were also reviewed. Results: Centrilobular nodules, mosaicism, and neovascularity were seen in both patient groups (p > 0.05). A significantly higher number of enlarged bronchial arteries were seen in patients with Eisenmenger syndrome. There was no correlation with pulmonary arterial pressures. Conclusion: Patients with idiopathic pulmonary arterial hypertension and Eisenmenger syndrome demonstrated similar pulmonary vascular changes on CT. These changes did not predict the underlying cause of pulmonary hypertension or its severity

Eisenmenger syndrome and idiopathic pulmonary arterial hypertension: do parenchymal lung changes reflect aetiology?

Energy Technology Data Exchange (ETDEWEB)

Griffin, N. [Royal Brompton and Harefield NHS Trust, London (United Kingdom)]. E-mail: nyreegriffin@hotmail.com; Allen, D. [Royal Brompton and Harefield NHS Trust, London (United Kingdom); Wort, J. [Royal Brompton and Harefield NHS Trust, London (United Kingdom); Rubens, M. [Royal Brompton and Harefield NHS Trust, London (United Kingdom); Padley, S. [Royal Brompton and Harefield NHS Trust, London (United Kingdom)

2007-06-15

Aim: To document the pulmonary vascular changes on thin-section computed tomography (CT) in patients with Eisenmenger syndrome and idiopathic pulmonary arterial hypertension, and to determine whether there is any correlation with pulmonary arterial pressures or the aetiology of pulmonary hypertension. Material and methods: From the National Pulmonary Hypertension Database, we identified eight patients with idiopathic pulmonary arterial hypertension and 20 patients with Eisenmenger syndrome (secondary to a ventriculoseptal defect) who had also undergone contrast-enhanced thin-section CT. CT studies were reviewed for the presence of centrilobular nodules, mosaicism, neovascularity, and bronchial artery hypertrophy. Haemodynamic data were also reviewed. Results: Centrilobular nodules, mosaicism, and neovascularity were seen in both patient groups (p > 0.05). A significantly higher number of enlarged bronchial arteries were seen in patients with Eisenmenger syndrome. There was no correlation with pulmonary arterial pressures. Conclusion: Patients with idiopathic pulmonary arterial hypertension and Eisenmenger syndrome demonstrated similar pulmonary vascular changes on CT. These changes did not predict the underlying cause of pulmonary hypertension or its severity.

Shared cognitive impairments and aetiology in ADHD symptoms and reading difficulties.

Directory of Open Access Journals (Sweden)

Celeste H M Cheung

Full Text Available Twin studies indicate that the frequent co-occurrence of attention deficit hyperactivity disorder (ADHD symptoms and reading difficulties (RD is largely due to shared genetic influences. Both disorders are associated with multiple cognitive impairments, but it remains unclear which cognitive impairments share the aetiological pathway, underlying the co-occurrence of the symptoms. We address this question using a sample of twins aged 7-10 and a range of cognitive measures previously associated with ADHD symptoms or RD.We performed multivariate structural equation modelling analyses on parent and teacher ratings on the ADHD symptom domains of inattention and hyperactivity, parent ratings on RD, and cognitive data on response inhibition (commission errors, CE, reaction time variability (RTV, verbal short-term memory (STM, working memory (WM and choice impulsivity, from a population sample of 1312 twins aged 7-10 years.Three cognitive processes showed significant phenotypic and genetic associations with both inattention symptoms and RD: RTV, verbal WM and STM. While STM captured only 11% of the shared genetic risk between inattention and RD, the estimates increased somewhat for WM (21% and RTV (28%; yet most of the genetic sharing between inattention and RD remained unaccounted for in each case.While response inhibition and choice impulsivity did not emerge as important cognitive processes underlying the co-occurrence between ADHD symptoms and RD, RTV and verbal memory processes separately showed significant phenotypic and genetic associations with both inattention symptoms and RD. Future studies employing longitudinal designs will be required to investigate the developmental pathways and direction of causality further.

Aetiological diagnosis of child deafness: CODEPEH recommendations.

Science.gov (United States)

Núñez-Batalla, Faustino; Jáudenes-Casaubón, Carmen; Sequí-Canet, Jose Miguel; Vivanco-Allende, Ana; Zubicaray-Ugarteche, Jose; Cabanillas-Farpón, Rubén

Important progress in the fields of molecular genetics (principally) and diagnostic imaging, together with the lack of a consensus protocol for guiding the diagnostic process after confirming deafness by neonatal screening, have led to this new work document drafted by the Spanish Commission for the Early Detection of Child Deafness (Spanish acronym: CODEPEH). This 2015 Recommendations Document, which is based on the most recent scientific evidence, provides guidance to professionals to support them in making decisions regarding aetiological diagnosis. Such diagnosis should be performed without delay and without impeding early intervention. Early identification of the causes of deafness offers many advantages: it prevents unnecessary trouble for the families, reduces health system expenses caused by performing different tests, and provides prognostic information that may guide therapeutic actions. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. All rights reserved.

Massive immunoglobulin treatment in women with four or more recurrent spontaneous primary abortions of unexplained aetiology.

Science.gov (United States)

Yamada, H; Kishida, T; Kobayashi, N; Kato, E H; Hoshi, N; Fujimoto, S

1998-09-01

The aim of this trial was to investigate the efficacy of massive i.v. immunoglobulin (MIVIg) treatment for women with a history of recurrent spontaneous abortion (RSA) due to unexplained aetiology. The study included nine women (11 pregnancies) with a history of four or more consecutive RSA with unexplained aetiology and no live births. The mean number of fetal losses was 4.5 (range 4-6 abortions). Over the course of 5 days, immunoglobulin (20 g/day) was infused i.v. at gestational weeks 4-7. No additional infusions were carried out. Two pregnancies out of the 11 conceptions resulted in missed abortions at gestational weeks 6 and 7 respectively. Mosaicism (46XX/ 48XX, +16, +20), and tetraploidy (92XXXX) were found by chromosome analyses of the two aborti. Eight out of the other nine pregnancies resulted in full term deliveries of healthy neonates. One pregnancy developed intrauterine growth retardation and fetal distress, resulting in a premature delivery (30 gestational weeks) by Caesarean section. Thus, excluding the two abortions with chromosome aberrations, the MIVIg treatment was effective in all nine pregnancies of RSA women with unexplained aetiology. This MIVIg treatment (100 g administered in early gestation) may be a beneficial alternative to previous IVIg infusion methods, and should be further evaluated in a multicentric, placebo-controlled study, employing a larger number of homogeneous patients who fall into a high risk category of first trimester abortions.

Role of Obesity in Asthma: Mechanisms and Management Strategies.

Science.gov (United States)

Scott, Hayley A; Wood, Lisa G; Gibson, Peter G

2017-08-01

Obesity is a commonly reported comorbidity in asthma, particularly in severe asthma. Obese asthmatics are highly symptomatic with a poor quality of life, despite using high-dose inhaled corticosteroids. While the clinical manifestations have been documented, the aetiologies of obese-asthma remain unclear. Several potential mechanisms have been proposed, including poor diet quality, physical inactivity and consequent accrual of excess adipose tissue. Each of these factors independently activates inflammatory pathways, potentially exerting effects in the airways. Because the origins of obesity are multifactorial, it is now believed there are multiple obese-asthma phenotypes, with varied aetiologies and clinical consequences. In this review, we will describe the clinical implications of obesity in people with asthma, our current understanding of the mechanisms driving this association and describe recently proposed obese-asthma phenotypes. We will then discuss how asthma management is complicated by obesity, and provide graded recommendations for the management of obesity in this population.

Thyrotoxicosis: an under-recognised aetiology.

Science.gov (United States)

Dave, Anjalee; Ludlow, Jason; Malaty, John

2015-05-20

A 53-year-old woman presented for evaluation of dizziness, shortness of breath and chest pain. She was found to be in atrial fibrillation with rapid ventricular response that was determined to be caused by iodine-induced thyrotoxicosis (from a CT scan with intravenous contrast 2 months prior to presentation). Jod-Basedow syndrome (iodine-induced hyperthyroidism) is infrequently considered as a cause of thyrotoxicosis, even when typical risk factors are present. However, this patient did not have typical risk factors: she did not reside in an iodine deficient area, did not have a prior diagnosis of thyroid disorder or goitre, had never been treated with thyroid medications or medications known to cause thyroid dysfunction and she presented later than is typical with this syndrome (2 months after receiving iodinated contrast). She had complete resolution of hyperthyroidism and atrial fibrillation 2 weeks later with no recurrence over the following 7 months. 2015 BMJ Publishing Group Ltd.

Additional perspectives on chronic kidney disease of unknown aetiology (CKDu) in Sri Lanka – lessons learned from the WHO CKDu population prevalence study

Science.gov (United States)

2014-01-01

The recent emergence of an apparently new form of chronic kidney disease of unknown aetiology (CKDu) has become a serious public health crisis in Sri Lanka. CKDu is slowly progressive, irreversible, and asymptomatic until late stages, and is not attributable to hypertension, diabetes, or other known aetiologies. In response to the scope and severity of the emerging CKDu health crisis, the Sri Lanka Ministry of Health and the World Health Organization initiated a collaborative research project from 2009 through 2012 to investigate CKDu prevalence and aetiology. The objective of this paper is to discuss the recently published findings of this investigation and present additional considerations and recommendations that may enhance subsequent investigations designed to identify and understand CKDu risk factors in Sri Lanka or other countries. PMID:25069485

Incidence, severity, aetiology and type of neck injury in men's amateur rugby union: a prospective cohort study

Directory of Open Access Journals (Sweden)

Pollard Henry P

2010-07-01

Full Text Available Abstract Background There is a paucity of epidemiological data on neck injury in amateur rugby union populations. The objective of this study was to determine the incidence, severity, aetiology and type of neck injury in Australian men's amateur rugby union. Methods Data was collected from a cohort of 262 participants from two Australian amateur men's rugby union clubs via a prospective cohort study design. A modified version of the Rugby Union Injury Report Form for Games and Training was used by the clubs physiotherapist or chiropractor in data collection. Results The participants sustained 90 (eight recurrent neck injuries. Exposure time was calculated at 31143.8 hours of play (12863.8 hours of match time and 18280 hours of training. Incidence of neck injury was 2.9 injuries/1000 player-hours (95%CI: 2.3, 3.6. As a consequence 69.3% neck injuries were minor, 17% mild, 6.8% moderate and 6.8% severe. Neck compression was the most frequent aetiology and was weakly associated with severity. Cervical facet injury was the most frequent neck injury type. Conclusions This is the first prospective cohort study in an amateur men's rugby union population since the inception of professionalism that presents injury rate, severity, aetiology and injury type data for neck injury. Current epidemiological data should be sought when evaluating the risks associated with rugby union football.

Molar-incisor-hypomineralisation (MIH). A retrospective clinical study in Greek children. II. Possible medical aetiological factors.

Science.gov (United States)

Lygidakis, N A; Dimou, G; Marinou, D

2008-12-01

This was to examine the potential medical aetiological factors involved in the development of MIH. During the years 2003--2005, all MIH cases diagnosed according to set criteria were selected from the new patients clinic of a Community Dental Centre for Children (Athens). The age, gender and teeth involved were recorded. A control group of socio-demographically matched controls was also identified. The potential aetiological factors were retrieved through personal interview with the parents and from each child and mother's medical book. Only verified aetiological factors were recorded. Evaluation of the correlation of affected teeth and the timing of the insult was performed in a separate group of 225 affected children aged 8-12 with their entire 12 'index' teeth erupted. From the 3,518, 5.5 to 12 years old children examined, 360 (10.2%) had MIH. Aetiology of MIH: 44 children (12.2%), presented without any relevant medical history, the remaining 316 (87.8%) recorded various medical problems associated with MIH, compared with 18.9% for controls. Perinatal (163, 33.6%) and postnatal (162, 33.9%) problems were the most frequently found and prenatal the least (33, 8.6%). For 42 children (11.7%) problems occurred in more than one chronological period, mainly during both the perinatal and postnatal period (11.1%). The most common prenatal problem was repeated episodes of high fever (12/33), in the perinatal period birth by Caesarean section (92/163) and other birth complications (34/163). Various respiratory conditions (88/162), repeated episodes of high fever (31/162) and neonatal illness (28/162) were the commonly reported problems in the postnatal period. Many MIH cases presented with more than one medical problem during the peri-and postnatal period. Children with MIH recorded 68.9% more frequent medical problems than controls (pMIH children with all their 'index' teeth erupted. Children with MIH present with more medical problems than controls during their prenatal

Assessment of the aetiological factors of non-specific (non gonococcal urethritis, taking burning micturition as criteria

Directory of Open Access Journals (Sweden)

Kuravi Anandam

1999-01-01

Full Text Available Out of 90 cases of non-specific urethritis investigated, aetiological factors could be found in 58 cases. However, in 45 cases i.e. 50%, the causative factors turned out to be common factors like pyogenic, fungal, and trichomonal infections only.

[The psychosomatics of chronic back pain. Classification, aetiology and therapy].

Science.gov (United States)

Henningsen, P

2004-05-01

An overview is given on the current classification, description and treatment of chronic pain with causally relevant psychological factors. It is based on the "practice guidelines on somatoform disorders" and on a thematically related meta-analysis. The classificatory problems, especially of the demarcation of somatoform and other chronic pain, are presented. Additional descriptive dimensions of the relevant psychosocial factors are: pain description, other organically unexplained pain- and non-pain-symptoms, anxiety and depression, disease conviction and illness behaviour, personality and childhood abuse. A modified psychotherapy for (somatoform) chronic pain is outlined. Finally, this aetiologically oriented psychosomatic-psychiatric approach is compared to psychological coping models for chronic pain.

Underlying role of mitochondrial mutagenesis in the pathogenesis of a disease and current approaches for translational research.

Science.gov (United States)

Paraskevaidi, Maria; Martin-Hirsch, Pierre L; Kyrgiou, Maria; Martin, Francis L

2017-05-01

Mitochondrial diseases have been extensively investigated over the last three decades, but many questions regarding their underlying aetiologies remain unanswered. Mitochondrial dysfunction is not only responsible for a range of neurological and myopathy diseases but also considered pivotal in a broader spectrum of common diseases such as epilepsy, autism and bipolar disorder. These disorders are a challenge to diagnose and treat, as their aetiology might be multifactorial. In this review, the focus is placed on potential mechanisms capable of introducing defects in mitochondria resulting in disease. Special attention is given to the influence of xenobiotics on mitochondria; environmental factors inducing mutations or epigenetic changes in the mitochondrial genome can alter its expression and impair the whole cell's functionality. Specifically, we suggest that environmental agents can cause damage in mitochondrial DNA and consequently lead to mutagenesis. Moreover, we describe current approaches for handling mitochondrial diseases, as well as available prenatal diagnostic tests, towards eliminating these maternally inherited diseases. Undoubtedly, more research is required, as current therapeutic approaches mostly employ palliative therapies rather than targeting primary mechanisms or prophylactic approaches. Much effort is needed into further unravelling the relationship between xenobiotics and mitochondria, as the extent of influence in mitochondrial pathogenesis is increasingly recognised. © The Author 2016. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Domestic donkey (Equus africanus asinus bites: An unusual aetiology of severe scalp injuries in Morocco

Directory of Open Access Journals (Sweden)

Hatim Droussi

2014-12-01

Discussion: The bite of a donkey is rare aetiology of scalp injuries. Special features of these injuries, including a literature review, are discussed focusing on the care of these patients in the emergency centre, describing the surgical procedures required and antibiotic choice. Recommendations for the management of donkey bite scalp injuries are provided.

Aetiologies of central nervous system infection in Viet Nam: a prospective provincial hospital-based descriptive surveillance study.

Directory of Open Access Journals (Sweden)

Nghia Ho Dang Trung

Full Text Available Infectious diseases of the central nervous system (CNS remain common and life-threatening, especially in developing countries. Knowledge of the aetiological agents responsible for these infections is essential to guide empiric therapy and develop a rational public health policy. To date most data has come from patients admitted to tertiary referral hospitals in Asia and there is limited aetiological data at the provincial hospital level where most patients are seen.We conducted a prospective Provincial Hospital-based descriptive surveillance study in adults and children at thirteen hospitals in central and southern Viet Nam between August 2007-April 2010. The pathogens of CNS infection were confirmed in CSF and blood samples by using classical microbiology, molecular diagnostics and serology.We recruited 1241 patients with clinically suspected infection of the CNS. An aetiological agent was identified in 640/1241 (52% of the patients. The most common pathogens were Streptococcus suis serotype 2 in patients older than 14 years of age (147/617, 24% and Japanese encephalitis virus in patients less than 14 years old (142/624, 23%. Mycobacterium tuberculosis was confirmed in 34/617 (6% adult patients and 11/624 (2% paediatric patients. The acute case fatality rate (CFR during hospital admission was 73/617 (12% in adults and to 42/624 (7% in children.Zoonotic bacterial and viral pathogens are the most common causes of CNS infection in adults and children in Viet Nam.

Pituitary transcription factors in the aetiology of combined pituitary hormone deficiency.

Science.gov (United States)

Pfäffle, R; Klammt, J

2011-02-01

The somatotropic axis is the central postnatal regulator of longitudinal growth. One of its major components--growth hormone--is produced by the anterior lobe of the pituitary, which also expresses and secretes five additional hormones (prolactin, thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone, adrenocorticotropic hormone). Proper development of the pituitary assures the regulation of critical processes such as metabolic control, puberty and reproduction, stress response and lactation. Ontogeny of the adenohypophysis is orchestrated by inputs from neighbouring tissues, cellular signalling molecules and transcription factors. Perturbation of expression or function of these factors has been implicated in the aetiology of combined pituitary hormone deficiency (CPHD). Mutations within the genes encoding for the transcription factors LHX3, LHX4, PROP1, and POU1F1 (PIT1) that act at different stages of pituitary development result in unique patterns of hormonal deficiencies reflecting their differential expression during organogenesis. In the case of LHX3 and LHX4 the phenotype may include extra-pituitary manifestations due to the function of these genes/proteins outside the pituitary gland. The remarkable variability in the clinical presentation of affected patients indicates the influence of the genetic background, environmental factors and possibly stochastic events. However, in the majority of CPHD cases the aetiology of this heterogeneous disease remains unexplained, which further suggests the involvement of additional genes. Identification of these factors might also help to close the gaps in our understanding of pituitary development, maintenance and function. Copyright © 2010 Elsevier Ltd. All rights reserved.

Viral pneumonia in adults in sub-Saharan Africa – epidemiology, aetiology, diagnosis and management

Directory of Open Access Journals (Sweden)

Antonia Ho

2014-06-01

Full Text Available Community-acquired pneumonia causes substantial morbidity and mortality in sub-Saharan Africa with an estimated 131 million new cases each year. Viruses – such as influenza virus, respiratory syncytial virus and parainfluenza virus – are now recognised as important causes of respiratory disease in older children and adults in the developed world following the emergence of sensitive molecular diagnostic tests, recent severe viral epidemics, and the discovery of novel viruses. Few studies have comprehensively evaluated the viral aetiology of adult pneumonia in Africa, but it is likely to differ from Western settings due to varying seasonality and the high proportion of patients with immunosuppression and co-morbidities. Emerging data suggest a high prevalence of viral pathogens, as well as multiple viral and viral/bacterial infections in African adults with pneumonia. However, the interpretation of positive results from highly sensitive polymerase chain reaction tests can be challenging. Therapeutic and preventative options against viral respiratory infections are currently limited in the African setting. This review summarises the current state of the epidemiology, aetiology, diagnosis and management of viral pneumonia in sub-Saharan Africa.

A Latter-day Saint Approach to Addiction: Aetiology, Consequences and Treatment in a Theological Context

Directory of Open Access Journals (Sweden)

James D. Holt

2014-12-01

Full Text Available This article explores the theological underpinning of the nature, aetiology and treatment of addictions within The Church of Jesus Christ of Latter-day Saints. The first section outlines the “plan of salvation” and how this provides the theological framework for the source and solution to addictions. The final section explores addiction against this background in terms of its aetiology, types, consequences and treatment in a Latter-day Saint context. In so doing it builds on the recognition by the Church in recent years that addiction is a problem in the lives of some of its members and that treatment programs coherent with its teachings and beliefs are necessary. The article concludes by suggesting that while addiction may be more openly discussed within a Latter-day Saint context there is a need to keep this dialogue moving forward. This article does not examine Latter-day Saint teaching within the wider context of psychotherapy and other definitions of addiction; rather it explores the place of addiction as understood within the theological and ecclesiological context of Mormonism.

DNA under Force: Mechanics, Electrostatics, and Hydration

Directory of Open Access Journals (Sweden)

Jingqiang Li

2015-02-01

Full Text Available Quantifying the basic intra- and inter-molecular forces of DNA has helped us to better understand and further predict the behavior of DNA. Single molecule technique elucidates the mechanics of DNA under applied external forces, sometimes under extreme forces. On the other hand, ensemble studies of DNA molecular force allow us to extend our understanding of DNA molecules under other forces such as electrostatic and hydration forces. Using a variety of techniques, we can have a comprehensive understanding of DNA molecular forces, which is crucial in unraveling the complex DNA functions in living cells as well as in designing a system that utilizes the unique properties of DNA in nanotechnology.

Enterovesical Fistulae: Aetiology, Imaging, and Management

Directory of Open Access Journals (Sweden)

Tomasz Golabek

2013-01-01

Full Text Available Background and Study Objectives. Enterovesical fistula (EVF is a devastating complication of a variety of inflammatory and neoplastic diseases. Radiological imaging plays a vital role in the diagnosis of EVF and is indispensable to gastroenterologists and surgeons for choosing the correct therapeutic option. This paper provides an overview of the diagnosis of enterovesical fistulae. The treatment of fistulae is also briefly discussed. Material and Methods. We performed a literature review by searching the Medline database for articles published from its inception until September 2013 based on clinical relevance. Electronic searches were limited to the keywords: “enterovesical fistula,” “colovesical fistula” (CVF, “pelvic fistula”, and “urinary fistula”. Results. EVF is a rare pathology. Diverticulitis is the commonest aetiology. Over two-thirds of affected patients describe pathognomonic features of pneumaturia, fecaluria, and recurrent urinary tract infections. Computed tomography is the modality of choice for the diagnosis of enterovesical fistulae as not only does it detect a fistula, but it also provides information about the surrounding anatomical structures. Conclusions. In the vast majority of cases, this condition is diagnosed because of unremitting urinary symptoms after gastroenterologist follow-up procedures for a diverticulitis or bowel inflammatory disease. Computed tomography is the most sensitive test for enterovesical fistula.

Turing mechanism underlying a branching model for lung morphogenesis.

Science.gov (United States)

Xu, Hui; Sun, Mingzhu; Zhao, Xin

2017-01-01

The mammalian lung develops through branching morphogenesis. Two primary forms of branching, which occur in order, in the lung have been identified: tip bifurcation and side branching. However, the mechanisms of lung branching morphogenesis remain to be explored. In our previous study, a biological mechanism was presented for lung branching pattern formation through a branching model. Here, we provide a mathematical mechanism underlying the branching patterns. By decoupling the branching model, we demonstrated the existence of Turing instability. We performed Turing instability analysis to reveal the mathematical mechanism of the branching patterns. Our simulation results show that the Turing patterns underlying the branching patterns are spot patterns that exhibit high local morphogen concentration. The high local morphogen concentration induces the growth of branching. Furthermore, we found that the sparse spot patterns underlie the tip bifurcation patterns, while the dense spot patterns underlies the side branching patterns. The dispersion relation analysis shows that the Turing wavelength affects the branching structure. As the wavelength decreases, the spot patterns change from sparse to dense, the rate of tip bifurcation decreases and side branching eventually occurs instead. In the process of transformation, there may exists hybrid branching that mixes tip bifurcation and side branching. Since experimental studies have reported that branching mode switching from side branching to tip bifurcation in the lung is under genetic control, our simulation results suggest that genes control the switch of the branching mode by regulating the Turing wavelength. Our results provide a novel insight into and understanding of the formation of branching patterns in the lung and other biological systems.

Aetiologies of Central Nervous System Infection in Viet Nam: A Prospective Provincial Hospital-Based Descriptive Surveillance Study

NARCIS (Netherlands)

Ho Dang Trung, Nghia; Le Thi Phuong, Tu; Wolbers, Marcel; Nguyen van Minh, Hoang; Nguyen Thanh, Vinh; van, Minh Pham; Thieu, Nga Tran Vu; van, Tan Le; Song, Diep To; Thi, Phuong Le; Thi Phuong, Thao Nguyen; van, Cong Bui; Tang, Vu; Ngoc Anh, Tuan Hoang; Nguyen, Dong; Trung, Tien Phan; Thi Nam, Lien Nguyen; Kiem, Hao Tran; Thi Thanh, Tam Nguyen; Campbell, James; Caws, Maxine; Day, Jeremy; de Jong, Menno D.; van Vinh, Chau Nguyen; van Doorn, H. Rogier; Tinh, Hien Tran; Farrar, Jeremy; Schultsz, Constance; Loi, Tran Quoc; Son, Nguyen Truong; Bay, Phan Van Be; Tham, Nguyen Thi Hong; Phuong, Le Thi; Tri, Le Trung; Binh, Nguyen Thi Nguyet; Du, Doan Cong; Thao, Nguyen Thi Phuong; Tien, Truong Thi My; La, Tran Thi Phi; Cong, Bui Van; Diep, Pham Ngoc; Dong, Duong Phuoc; Lanh, Tran Thi Mong; Dom, Pham Van; Dung, Tran Quang; Tri, Phan Nhut; Ho, Tang Thi; Tai, Nguyen Anh; Luc, Quach Van; Phuoc, Dinh Xuan

2012-01-01

Background: Infectious diseases of the central nervous system (CNS) remain common and life-threatening, especially in developing countries. Knowledge of the aetiological agents responsible for these infections is essential to guide empiric therapy and develop a rational public health policy. To date

[Recent progress in neurobiological mechanisms of depression].

Science.gov (United States)

Gao, Yu-Bo; Li, Liang-Ping; Zhu, Xin-Hong; Gao, Tian-Ming

2012-08-25

Revealing the neurobiological mechanism of depression has always been a big challenge in the field of neuroscience. Not only are depressive syndromes heterogeneous and their aetiologies diverse, but also some symptoms are impossible to reproduce in animal models. Nevertheless, great progress has been made on the understanding and treatment of depression in recent years. In this review, we focus on key leading hypotheses in the neurobiological mechanism of depression, examine their strengths and weaknesses critically, and also highlight new insights that promise to extend the understanding of depression and its treatment.

A Molecular Neurobiological Approach to Understanding the Aetiology of Chronic Fatigue Syndrome (Myalgic Encephalomyelitis or Systemic Exertion Intolerance Disease) with Treatment Implications.

Science.gov (United States)

Monro, Jean A; Puri, Basant K

2018-02-06

Currently, a psychologically based model is widely held to be the basis for the aetiology and treatment of chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME)/systemic exertion intolerance disease (SEID). However, an alternative, molecular neurobiological approach is possible and in this paper evidence demonstrating a biological aetiology for CFS/ME/SEID is adduced from a study of the history of the disease and a consideration of the role of the following in this disease: nitric oxide and peroxynitrite, oxidative and nitrosative stress, the blood-brain barrier and intestinal permeability, cytokines and infections, metabolism, structural and chemical brain changes, neurophysiological changes and calcium ion mobilisation. Evidence is also detailed for biologically based potential therapeutic options, including: nutritional supplementation, for example in order to downregulate the nitric oxide-peroxynitrite cycle to prevent its perpetuation; antiviral therapy; and monoclonal antibody treatment. It is concluded that there is strong evidence of a molecular neurobiological aetiology, and so it is suggested that biologically based therapeutic interventions should constitute a focus for future research into CFS/ME/SEID.

The incidence, aetiology and outcome of acute seizures in children admitted to a rural Kenyan district hospital

NARCIS (Netherlands)

Idro, Richard; Gwer, Samson; Kahindi, Michael; Gatakaa, Hellen; Kazungu, Tony; Ndiritu, Moses; Maitland, Kathryn; Neville, Brian G. R.; Kager, Piet A.; Newton, Charles R. J. C.

2008-01-01

BACKGROUND: Acute seizures are a common cause of paediatric admissions to hospitals in resource poor countries and a risk factor for neurological and cognitive impairment and epilepsy. We determined the incidence, aetiological factors and the immediate outcome of seizures in a rural malaria endemic

Amount of fear extinction changes its underlying mechanisms.

Science.gov (United States)

An, Bobae; Kim, Jihye; Park, Kyungjoon; Lee, Sukwon; Song, Sukwoon; Choi, Sukwoo

2017-07-03

There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.

Control of a perturbed under-actuated mechanical system

KAUST Repository

Zayane, Chadia; Laleg-Kirati, Taous-Meriem; Chemori, Ahmed

2015-01-01

In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed

Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Trung Dung; Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia)

2014-05-05

Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

A STUDY OF THE VARIED AETIOLOGY AND CLINICAL PRESENTATION OF NEW ONSET SEIZURES IN POSTPARTUM PERIOD

Directory of Open Access Journals (Sweden)

Ravindra Kumar Sudarsi

2016-08-01

Full Text Available BACKGROUND Seizures in the postpartum period are the major cause of mortality and morbidity. A variety of neurological disorders causing seizures may be encountered during pregnancy and puerperium. These disorders may be unrelated to pregnancy (e.g. Meningitis or peculiar to pregnancy (e.g. Eclampsia or. Pregnancy may affect the course of the pre-existing neurological disorders such as epilepsy. So, keeping in mind the varied aetiology of postpartum seizures and its response to appropriate treatment, our study has been conducted to find out the most common causes in our setup to guide the optimal therapy. AIM OF THE STUDY To study the varied aetiology and clinical presentation of new onset seizures in the postpartum period over a period of two years. MATERIALS AND METHODS 50 patients who developed first episode of seizures in postpartum period (that is after delivery to 6 weeks admitted to Osmania General Hospital on random selection. All women complaining of new onset seizure with in postpartum period up to 6 weeks. All those women who are known epileptics and who had seizures in the antenatal period were excluded from the study. The selected patients were studied in detail with history and physical examination. RESULTS Different causes for first episode of seizures in postpartum period are enlisted here. Cavernous sinus thrombosis in 17 patients, late postpartum eclampsia accounted for 13 patients, intracranial haemorrhage in 6 patients, ischaemic stroke in 5 patients, posterior reversible encephalopathy syndrome in 4 patients, CNS infections in 6 patients, glioma in 1 patient, viral hepatitis in one patient, idiopathic in 3 patients. CONCLUSIONS Cavernous sinus thrombosis and late postpartum eclampsia constitute the major aetiology of first onset of seizes occurring in the postpartum period.

Deformation Mechanisms of Gum Metals Under Nanoindentation

Science.gov (United States)

Sankaran, Rohini Priya

defect structures to applied loading, we perform ex-situ nanoindentation. Nanoindentation is a convenient method as the plastic deformation is localized and probes a nominally defect free volume of the material. We subsequently characterize the defect structures in these alloys with both conventional TEM and advanced techniques such as HAADF HRSTEM and nanoprobe diffraction. These advanced techniques allow for a more thorough understanding of the observed deformation features. The main findings from this investigation are as follows. As expected we observe that a non-equilibrium phase, o, is present in the leaner beta-stabilized alloy, ST Ref-1. We do not find any direct evidence of secondary phases in STGM, and we find the beta phase in CWGM, along with lath microstructure with subgrain structure consisting of dislocation cell networks. Upon nanoindentation, we find twinning accompanied by beta nucleation on the twin boundary in ST Ref-1 samples. This result is consistent with previous findings and is reasonable considering the alloy is unstable with respect to beta transformation. We find deformation nanotwinning in cold worked gum metals under nanoindentation, which is initially surprising. We argue that when viewed as a nanocrystalline material, such a deformation mechanism is consistent with previous work, and furthermore, a deformation nanotwinned structure does not preclude an ideal shear mechanism from operating in the alloy. Lastly, we observe continuous lattice rotations in STGM under nanoindentation via nanoprobe diffraction. With this technique, for the first time we can demonstrate that the lattice rotations are truly continuous at the nanoscale. We can quantify this lattice rotation, and find that even though the rotation is large, it may be mediated by a reasonable geometrically necessary dislocation density, and note that similar rotations are typically observed in other materials under nanoindentation. HRSTEM and conventional TEM data confirm the

Genetic evidence implicates the immune system and cholesterol metabolism in the aetiology of Alzheimer's disease.

Directory of Open Access Journals (Sweden)

Lesley Jones

2010-11-01

Full Text Available Late Onset Alzheimer's disease (LOAD is the leading cause of dementia. Recent large genome-wide association studies (GWAS identified the first strongly supported LOAD susceptibility genes since the discovery of the involvement of APOE in the early 1990s. We have now exploited these GWAS datasets to uncover key LOAD pathophysiological processes.We applied a recently developed tool for mining GWAS data for biologically meaningful information to a LOAD GWAS dataset. The principal findings were then tested in an independent GWAS dataset.We found a significant overrepresentation of association signals in pathways related to cholesterol metabolism and the immune response in both of the two largest genome-wide association studies for LOAD.Processes related to cholesterol metabolism and the innate immune response have previously been implicated by pathological and epidemiological studies of Alzheimer's disease, but it has been unclear whether those findings reflected primary aetiological events or consequences of the disease process. Our independent evidence from two large studies now demonstrates that these processes are aetiologically relevant, and suggests that they may be suitable targets for novel and existing therapeutic approaches.

Panhypopituitarism due to Absence of the Pituitary Stalk: A Rare Aetiology of Liver Cirrhosis.

Science.gov (United States)

Gonzalez Rozas, Marta; Hernanz Roman, Lidia; Gonzalez, Diego Gonzalez; Pérez-Castrillón, José Luis

2016-01-01

Studies have established a relationship between hypothalamic-pituitary dysfunction and the onset of liver damage, which may occasionally progress to cirrhosis. Patients with hypopituitarism can develop a metabolic syndrome-like phenotype. Insulin resistance is the main pathophysiological axis of metabolic syndrome and is the causal factor in the development of nonalcoholic fatty liver disease (NAFLD). We present the case of a young patient with liver cirrhosis of unknown aetiology that was finally attributed to panhypopituitarism.

A ten-year analysis of the traumatic maxillofacial and brain injury patient in Amsterdam: incidence and aetiology

NARCIS (Netherlands)

Salentijn, E.G.; Peerdeman, S.M.; Boffano, P.; van den Bergh, B.; Forouzanfar, T.

2014-01-01

In the literature it is questioned if the presence of maxillofacial trauma is associated with the presence of brain injury. The aim of this study is to present a 10-year retrospective study of the incidence and aetiology of maxillofacial trauma associated with brain injury that required both oral

A ten-year analysis of the traumatic maxillofacial and brain injury patient in Amsterdam: Incidence and aetiology

NARCIS (Netherlands)

Salentijn, E.G.; Peerdeman, S.M.; Boffano, P.; van den Bergh, B.; Forouzanfar, T.

2014-01-01

In the literature it is questioned if the presence of maxillofacial trauma is associated with the presence of brain injury. The aim of this study is to present a 10-year retrospective study of the incidence and aetiology of maxillofacial trauma associated with brain injury that required both oral

Cell-Nonautonomous Mechanisms Underlying Cellular and Organismal Aging.

Science.gov (United States)

Medkour, Younes; Svistkova, Veronika; Titorenko, Vladimir I

2016-01-01

Cell-autonomous mechanisms underlying cellular and organismal aging in evolutionarily distant eukaryotes have been established; these mechanisms regulate longevity-defining processes within a single eukaryotic cell. Recent findings have provided valuable insight into cell-nonautonomous mechanisms modulating cellular and organismal aging in eukaryotes across phyla; these mechanisms involve a transmission of various longevity factors between different cells, tissues, and organisms. Herein, we review such cell-nonautonomous mechanisms of aging in eukaryotes. We discuss the following: (1) how low molecular weight transmissible longevity factors modulate aging and define longevity of cells in yeast populations cultured in liquid media or on solid surfaces, (2) how communications between proteostasis stress networks operating in neurons and nonneuronal somatic tissues define longevity of the nematode Caenorhabditis elegans by modulating the rates of aging in different tissues, and (3) how different bacterial species colonizing the gut lumen of C. elegans define nematode longevity by modulating the rate of organismal aging. Copyright © 2016. Published by Elsevier Inc.

Crack assessment of pipe under combined thermal and mechanical load

International Nuclear Information System (INIS)

Song, Tae Kwang; Kim, Yun Jae

2009-01-01

In this paper, J-integral and transient C(t)-integral, which were key parameters in low temperature and high temperature fracture mechanics, under combined thermal and mechanical load were estimated via 3-dimensional finite element analyses. Various type of thermal and mechanical load, material hardening were considered to decrease conservatism in existing solutions. As a results, V-factor and redistribution time for combined thermal and mechanical load were proposed to calculate J-integral and C(t)-integral, respectively.

Chronic kidney disease of unknown aetiology in Sri Lanka: is cadmium a likely cause?

Directory of Open Access Journals (Sweden)

Peiris-John Roshini J

2011-07-01

Full Text Available Abstract Background The rising prevalence of chronic kidney disease (CKD and subsequent end stage renal failure necessitating renal replacement therapy has profound consequences for affected individuals and health care resources. This community based study was conducted to identify potential predictors of microalbuminuria in a randomly selected sample of adults from the North Central Province (NCP of Sri Lanka, where the burden of CKD is pronounced and the underlying cause still unknown. Methods Exposures to possible risk factors were determined in randomly recruited subjects (425 females and 461 males from selected areas of the NCP of Sri Lanka using an interviewer administered questionnaire. Sulphosalicylic acid and the Light Dependent Resister microalbumin gel filtration method was used for initial screening for microalbuminuria and reconfirmed by the Micral strip test. Results Microalbumnuria was detected in 6.1% of the females and 8.5% of the males. Smoking (p Conclusions Hypertension, diabetes mellitus, UTI, and smoking are known risk factors for microalbuminuria. The association between microalbuminuria and consumption of well water suggests an environmental aetiology to CKD in NCP. The causative agent is yet to be identified. Investigations for cadmium as a potential causative agent needs to be initiated.

Classification of hand eczema: clinical and aetiological types. Based on the guideline of the Danish Contact Dermatitis Group

DEFF Research Database (Denmark)

Johansen, Jeanne Duus; Hald, Marianne; Andersen, Bo Lasthein

2011-01-01

Background. No generally accepted classification scheme for hand eczema exists. The Danish Contact Dermatitis Group recently developed a guideline defining common clinical types and providing criteria for aetiological types. Objectives. To test the concepts of this guideline in a group of hand...

[Functional impairment and radiologic fasciitis under erlotinib therapy].

Science.gov (United States)

Osdoit, S; Wierzbicka, E; Guillet, G

2011-01-01

Targeted molecules are recent and valuable weapons in the management of certain cancers. Among them, erlotinib is an inhibitor of epidermal growth factor receptor approved in non-small lung cancer and pancreatic cancer after failure of first line treatment. Erlotinib is responsible for many cutaneous side effects. We report a case of acute symptomatic fasciitis that has occurred during erlotinib therapy. To our knowledge it is the first case described. A 56-year-old man was treated with erlotinib for a metastatic non-small lung adenocarcinoma. Shortly after the treatment by erlotinib was introduced, he had a severe acneiform rash resistant to doxycycline treatment. After a year of treatment, he presented intense pain in the legs with functional impairment. Medical imaging confirmed fasciitis. It regressed along with the rash after using strong topical corticosteroids during ten days. Besides bacterial fasciitis, inflammatory and oedematous fasciitis have varied aetiologies. The occurrence of a documented fasciitis during anti EGFR-therapy is original and raises the question of underlying mechanism. We suggest three pathophysiological mechanisms: spreading by contiguity; paraneoplastic fasciitis, or specific lesion of the fascia due to anti-EGFR. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Causal inference regarding infectious aetiology of chronic conditions: a systematic review.

Directory of Open Access Journals (Sweden)

Sofia Orrskog

Full Text Available BACKGROUND: The global burden of disease has shifted from communicable diseases in children to chronic diseases in adults. This epidemiologic shift varies greatly by region, but in Europe, chronic conditions account for 86% of all deaths, 77% of the disease burden, and up to 80% of health care expenditures. A number of risk factors have been implicated in chronic diseases, such as exposure to infectious agents. A number of associations have been well established while others remain uncertain. METHODS AND FINDINGS: We assessed the body of evidence regarding the infectious aetiology of chronic diseases in the peer-reviewed literature over the last decade. Causality was assessed with three different criteria: First, the total number of associations documented in the literature between each infectious agent and chronic condition; second, the epidemiologic study design (quality of the study; third, evidence for the number of Hill's criteria and Koch's postulates that linked the pathogen with the chronic condition. We identified 3136 publications, of which 148 were included in the analysis. There were a total of 75 different infectious agents and 122 chronic conditions. The evidence was strong for five pathogens, based on study type, strength and number of associations; they accounted for 60% of the associations documented in the literature. They were human immunodeficiency virus, hepatitis C virus, Helicobacter pylori, hepatitis B virus, and Chlamydia pneumoniae and were collectively implicated in the aetiology of 37 different chronic conditions. Other pathogens examined were only associated with very few chronic conditions (≤ 3 and when applying the three different criteria of evidence the strength of the causality was weak. CONCLUSIONS: Prevention and treatment of these five pathogens lend themselves as effective public health intervention entry points. By concentrating research efforts on these promising areas, the human, economic, and societal

Incidence, aetiology and injury characteristics of traumatic spinal cord injury in Stockholm, Sweden: A prospective, population-based update.

Science.gov (United States)

Joseph, Conran; Andersson, Nina; Bjelak, Sapko; Giesecke, Kajsa; Hultling, Claes; Nilsson Wikmar, Lena; Phillips, Julie; Seiger, Åke; Stenimahitis, Vasilios; Trok, Katarzyna; Åkesson, Elisabet; Wahman, Kerstin

2017-05-16

To update the incidence rate, aetiology and injury characteristics of acutely-injured adults with traumatic spinal cord injury in Stockholm, Sweden, using international standards of reporting. Prospective, (regional) population-based observation. Forty-nine consecutively enrolled individuals. A surveillance system of newly-injured adults with traumatic spinal cord injury was implemented for an 18-month period. The International Spinal Cord Injury Core Data Set was used to collect data on those who survived the first 7 days post-injury. After an 18-month period, 49 incident cases were registered, of whom 45 were included in this study. The crude incidence rate was 19.0 per million, consisting mainly of men (60%), and the mean age of the cohort was 55 years (median 58). Causes of injury were almost exclusively limited to falls and transport-related events, accounting for 58% and 40% of cases, respectively. The incidence has remained stable when compared with the previous study; however, significant differences exist for injury aetiology (p = 0.004) and impairment level (p = 0.01) in that more fall- and transport-related spinal cord injury occurred, and a larger proportion of persons was left with resultant tetraplegia, in the current study, compared with more sport-related injuries and those left with paraplegia in the previous study. The incidence rate appeared to remain stable in Stockholm, Sweden. However, significant changes in injury aetiology and impairment-level post injury were found, compared with the previous study. There remains a need for developing fall-related prevention strategies in rehabilitation settings as well as in population-based programmes.

CLINICAL OUTCOME OF PENETRATING KERATOPLASTY IN CORNEAL OPACITIES OF DIFFERENT AETIOLOGY- A CLINICAL STUDY

Directory of Open Access Journals (Sweden)

Dipak Bhuyan

2017-01-01

Full Text Available BACKGROUND Corneal transplantation or grafting is an operation in which abnormal corneal host tissue is replaced by healthy donor cornea. According to the World Health Organization (WHO, corneal diseases are among the major causes of vision loss and blindness in the world today after cataract and glaucoma. The aim of the study is to- 1. Evaluate the different aetiology of corneal opacity including active infective aetiology as indicated for penetrating keratoplasty. 2. Determine the clinical outcome of penetrating keratoplasty in relation to graft survival, graft rejection and peri-operative complications in different aetiology groups. 3. Determine the final visual outcome. MATERIALS AND METHODS Candidates for keratoplasty were selected from- 1. Eye Bank of Regional Institute of Ophthalmology (R.I.O. 2. R.I.O OPD. The study period was from September 2014 to August 2015. 30 cases were taken in the study. Descriptive statistics were applied to analyse the data wherever necessary. RESULTS 34.6±19.73 yrs. (mean±SD was the mean age at which transplants were done in the study. Out of total 30 cases, 13 (43.33% and 17 (56.66% were male and female, respectively. The different indications for penetrating keratoplasty are- Post ulcer corneal opacity in 14 cases (46.66%, posttraumatic corneal opacity 9 cases (30%, pseudophakic bullous keratopathy 4 cases (13.33%, corneal dystrophy in 2 cases (6.66% and non-healing corneal ulcer in 1 case (3.33%. 16 cases (53.33% showed clear graft till the last follow up while 11 (33.33% cases showed partially clear graft resulting in improved visual outcome while 3 cases (10.00% of the grafts were opaque due to graft failure. CONCLUSION The major indications for penetrating keratoplasty in this part of the world are post ulcer and posttraumatic corneal opacity and majority of them are illiterate agricultural workers who failed to get adequate treatment on time. Graft survival rate is high, which can be attributed to the

Aetiology-Specific Estimates of the Global and Regional Incidence and Mortality of Diarrhoeal Diseases Commonly Transmitted through Food

DEFF Research Database (Denmark)

Pires, Sara Monteiro; Fischer-Walker, Christa L; Lanata, Claudio F

2015-01-01

Diarrhoeal diseases are major contributors to the global burden of disease, particularly in children. However, comprehensive estimates of the incidence and mortality due to specific aetiologies of diarrhoeal diseases are not available. The objective of this study is to provide estimates of the gl...

Chicken astrovirus as an aetiological agent of runting-stunting syndrome in broiler chickens.

Science.gov (United States)

Kang, Kyung-Il; Linnemann, Erich; Icard, Alan H; Durairaj, Vijay; Mundt, Egbert; Sellers, Holly S

2018-04-01

Despite descriptions of runting-stunting syndrome (RSS) in broiler chickens dating back over 40 years, the aetiology has not yet been described. A novel chicken astrovirus (CkAstV) was isolated in an LMH liver cell line from the intestines of chickens affected with RSS. Clinical RSS is characterized by retarded growth and cystic crypt lesions in the small intestine. In 1-day-old broiler chickens infected with the CkAstV isolate, virus was only detected in the intestinal epithelial cells during the first few days after infection. Notably, the preferred host cells are the crypt epithelial cells following initial replication in the villous epithelial cells, thus implying viral preference for immature intestinal cells. Nevertheless, the CkAstV isolate did not induce remarkable pathological changes, despite the presence of the virus in situ. Serial chicken-to-chicken passages of the virus induced increased virulence, as displayed by decreased weight gain and the presence of cystic lesions in the small intestine reproducing clinical RSS in chickens. The analysis of the full-length genome sequences from the isolated CkAstV and the CkAstV from the bird-to-bird passages showed >99 % similarity. The data obtained in this study suggest that the CkAstV isolate is capable of inducing RSS following serial bird-to-bird passages in broilers and is as an aetiological agent of the disease.

Panhypopituitarism due to Absence of the Pituitary Stalk: A Rare Aetiology of Liver Cirrhosis

Directory of Open Access Journals (Sweden)

Marta Gonzalez Rozas

2016-01-01

Full Text Available Studies have established a relationship between hypothalamic-pituitary dysfunction and the onset of liver damage, which may occasionally progress to cirrhosis. Patients with hypopituitarism can develop a metabolic syndrome-like phenotype. Insulin resistance is the main pathophysiological axis of metabolic syndrome and is the causal factor in the development of nonalcoholic fatty liver disease (NAFLD. We present the case of a young patient with liver cirrhosis of unknown aetiology that was finally attributed to panhypopituitarism.

Aetiology and mechanisms of injury in medial tibial stress syndrome: Current and future developments

Science.gov (United States)

Franklyn, Melanie; Oakes, Barry

2015-01-01

Medial tibial stress syndrome (MTSS) is a debilitating overuse injury of the tibia sustained by individuals who perform recurrent impact exercise such as athletes and military recruits. Characterised by diffuse tibial anteromedial or posteromedial surface subcutaneous periostitis, in most cases it is also an injury involving underlying cortical bone microtrauma, although it is not clear if the soft tissue or cortical bone reaction occurs first. Nuclear bone scans and magnetic resonance imaging (MRI) can both be used for the diagnosis of MTSS, but the patient’s history and clinical symptoms need to be considered in conjunction with the imaging findings for a correct interpretation of the results, as both imaging modalities have demonstrated positive findings in the absence of injury. However, MRI is rapidly becoming the preferred imaging modality for the diagnosis of bone stress injuries. It can also be used for the early diagnosis of MTSS, as the developing periosteal oedema can be identified. Retrospective studies have demonstrated that MTSS patients have lower bone mineral density (BMD) at the injury site than exercising controls, and preliminary data indicates the BMD is lower in MTSS subjects than tibial stress fracture (TSF) subjects. The values of a number of tibial geometric parameters such as cross-sectional area and section modulus are also lower in MTSS subjects than exercising controls, but not as low as the values in TSF subjects. Thus, the balance between BMD and cortical bone geometry may predict an individual's likelihood of developing MTSS. However, prospective longitudinal studies are needed to determine how these factors alter during the development of the injury and to find the detailed structural cause, which is still unknown. Finite element analysis has recently been used to examine the mechanisms involved in tibial stress injuries and offer a promising future tool to understand the mechanisms involved in MTSS. Contemporary accurate diagnosis

Aetiology and mechanisms of injury in medial tibial stress syndrome: Current and future developments.

Science.gov (United States)

Franklyn, Melanie; Oakes, Barry

2015-09-18

Medial tibial stress syndrome (MTSS) is a debilitating overuse injury of the tibia sustained by individuals who perform recurrent impact exercise such as athletes and military recruits. Characterised by diffuse tibial anteromedial or posteromedial surface subcutaneous periostitis, in most cases it is also an injury involving underlying cortical bone microtrauma, although it is not clear if the soft tissue or cortical bone reaction occurs first. Nuclear bone scans and magnetic resonance imaging (MRI) can both be used for the diagnosis of MTSS, but the patient's history and clinical symptoms need to be considered in conjunction with the imaging findings for a correct interpretation of the results, as both imaging modalities have demonstrated positive findings in the absence of injury. However, MRI is rapidly becoming the preferred imaging modality for the diagnosis of bone stress injuries. It can also be used for the early diagnosis of MTSS, as the developing periosteal oedema can be identified. Retrospective studies have demonstrated that MTSS patients have lower bone mineral density (BMD) at the injury site than exercising controls, and preliminary data indicates the BMD is lower in MTSS subjects than tibial stress fracture (TSF) subjects. The values of a number of tibial geometric parameters such as cross-sectional area and section modulus are also lower in MTSS subjects than exercising controls, but not as low as the values in TSF subjects. Thus, the balance between BMD and cortical bone geometry may predict an individual's likelihood of developing MTSS. However, prospective longitudinal studies are needed to determine how these factors alter during the development of the injury and to find the detailed structural cause, which is still unknown. Finite element analysis has recently been used to examine the mechanisms involved in tibial stress injuries and offer a promising future tool to understand the mechanisms involved in MTSS. Contemporary accurate diagnosis

Mechanism of crack initiation and crack growth under thermal and mechanical fatigue loading

Energy Technology Data Exchange (ETDEWEB)

Utz, S.; Soppa, E.; Silcher, H.; Kohler, C. [Stuttgart Univ. (Germany). Materials Testing Inst.

2013-07-01

The present contribution is focused on the experimental investigations and numerical simulations of the deformation behaviour and crack development in the austenitic stainless steel X6CrNiNb18-10 under thermal and mechanical cyclic loading in HCF and LCF regimes. The main objective of this research is the understanding of the basic mechanisms of fatigue damage and the development of simulation methods, which can be applied further in safety evaluations of nuclear power plant components. In this context the modelling of crack initiation and crack growth inside the material structure induced by varying thermal or mechanical loads are of particular interest. The mechanisms of crack initiation depend among other things on the type of loading, microstructure, material properties and temperature. The Nb-stabilized austenitic stainless steel in the solution-annealed condition was chosen for the investigations. Experiments with two kinds of cyclic loading - pure thermal and pure mechanical - were carried out and simulated. The fatigue behaviour of the steel X6CrNiNb18-10 under thermal loading was studied within the framework of the joint research project [4]. Interrupted thermal cyclic tests in the temperature range of 150 C to 300 C combined with non-destructive residual stress measurements (XRD) and various microscopic investigations, e.g. in SEM (Scanning Electron Microscope), were used to study the effects of thermal cyclic loading on the material. This thermal cyclic loading leads to thermal induced stresses and strains. As a result intrusions and extrusions appear inside the grains (at the surface), at which microcracks arise and evolve to a dominant crack. Finally, these microcracks cause a continuous and significant decrease of residual stresses. The fatigue behaviour of the steel X6CrNiNb18-10 under mechanical loading at room temperature was studied within the framework of the research project [5], [8]. With a combination of interrupted LCF tests and EBSD

Mechanism of crack initiation and crack growth under thermal and mechanical fatigue loading

International Nuclear Information System (INIS)

Utz, S.; Soppa, E.; Silcher, H.; Kohler, C.

2013-01-01

The present contribution is focused on the experimental investigations and numerical simulations of the deformation behaviour and crack development in the austenitic stainless steel X6CrNiNb18-10 under thermal and mechanical cyclic loading in HCF and LCF regimes. The main objective of this research is the understanding of the basic mechanisms of fatigue damage and the development of simulation methods, which can be applied further in safety evaluations of nuclear power plant components. In this context the modelling of crack initiation and crack growth inside the material structure induced by varying thermal or mechanical loads are of particular interest. The mechanisms of crack initiation depend among other things on the type of loading, microstructure, material properties and temperature. The Nb-stabilized austenitic stainless steel in the solution-annealed condition was chosen for the investigations. Experiments with two kinds of cyclic loading - pure thermal and pure mechanical - were carried out and simulated. The fatigue behaviour of the steel X6CrNiNb18-10 under thermal loading was studied within the framework of the joint research project [4]. Interrupted thermal cyclic tests in the temperature range of 150 C to 300 C combined with non-destructive residual stress measurements (XRD) and various microscopic investigations, e.g. in SEM (Scanning Electron Microscope), were used to study the effects of thermal cyclic loading on the material. This thermal cyclic loading leads to thermal induced stresses and strains. As a result intrusions and extrusions appear inside the grains (at the surface), at which microcracks arise and evolve to a dominant crack. Finally, these microcracks cause a continuous and significant decrease of residual stresses. The fatigue behaviour of the steel X6CrNiNb18-10 under mechanical loading at room temperature was studied within the framework of the research project [5], [8]. With a combination of interrupted LCF tests and EBSD

INFECTIOUS AETIOLOGY OF MARGINAL ZONE LYMPHOMA AND ROLE OF ANTI-INFECTIVE THERAPY

Directory of Open Access Journals (Sweden)

Salvatore Perrone

2016-01-01

Full Text Available Marginal zone lymphomas have been associated with several infectious agents covering both viral and bacterial pathogens and in some cases a clear aetiological role has been established. Pathogenetic mechanisms are currently not completely understood, however the role of chronic stimulation of the host immune response with persistent lymphocyte activation represents the most convincing explanation for lymphoproliferation. Gastric MALT lymphoma is strictly associated with Helicobacter pylori infection and various eradicating protocols, developed due to increasing antibiotic resistance, represent the first line therapy. The response rate to eradication is good with 80% of response at 1 year; this finding is also noteworthy because recapitulates a cancer cured only by antibacterial approach and it satisfies the Koch postulates of causation, establishing a causative relationship between Hp and gastric MALT lymphoma. Patients with chronic HCV infection have 5 times higher risk to develop MZL, in particular an association with splenic and nodal MZL has been shown in several studies. Moreover, there is evidence of lymphoma regression after antiviral therapy with interferon+ribavirin, thus rising hope that new available drugs, extremely effective against HCV replication, could improve outcome also in HCV-driven lymphomas. The rare cases of MZL localized to orbital fat and eye conjunctivas have been associated with Chlamydia psittaci infection carried by birds. Efficacy of antibacterial therapy against C. psittaci are conflicting and generally poorer thain gastric MALT. Finally some case-reports will cover the relationship between primary cutaneous B-cell Lymphomas and Borrelia Burgdorferi.

Fracture mechanics of hydroxyapatite single crystals under geometric confinement.

Science.gov (United States)

Libonati, Flavia; Nair, Arun K; Vergani, Laura; Buehler, Markus J

2013-04-01

Geometric confinement to the nanoscale, a concept that refers to the characteristic dimensions of structural features of materials at this length scale, has been shown to control the mechanical behavior of many biological materials or their building blocks, and such effects have also been suggested to play a crucial role in enhancing the strength and toughness of bone. Here we study the effect of geometric confinement on the fracture mechanism of hydroxyapatite (HAP) crystals that form the mineralized phase in bone. We report a series of molecular simulations of HAP crystals with an edge crack on the (001) plane under tensile loading, and we systematically vary the sample height whilst keeping the sample and the crack length constant. We find that by decreasing the sample height the stress concentration at the tip of the crack disappears for samples with a height smaller than 4.15nm, below which the material shows a different failure mode characterized by a more ductile mechanism with much larger failure strains, and the strength approaching that of a flaw-less crystal. This study directly confirms an earlier suggestion of a flaw-tolerant state that appears under geometric confinement and may explain the mechanical stability of the reinforcing HAP platelets in bone. Copyright © 2012 Elsevier Ltd. All rights reserved.

Believing versus interacting: Behavioural and neural mechanisms underlying interpersonal coordination

DEFF Research Database (Denmark)

Konvalinka, Ivana; Bauer, Markus; Kilner, James

When two people engage in a bidirectional interaction with each other, they use both bottom-up sensorimotor mechanisms such as monitoring and adapting to the behaviour of the other, as well as top-down cognitive processes, modulating their beliefs and allowing them to make decisions. Most research...... in joint action has investigated only one of these mechanisms at a time – low-level processes underlying joint coordination, or high-level cognitive mechanisms that give insight into how people think about another. In real interactions, interplay between these two mechanisms modulates how we interact...

AETIOLOGY AND CLINICAL PROFILE OF ORAL CANCERS IN PATIENTS ATTENDING A TERTIARY CARE HOSPITAL IN RURAL KERALA

Directory of Open Access Journals (Sweden)

Thulaseedharan Sreedharan

2016-11-01

Full Text Available BACKGROUND Oral cancer is the sixth most common cancer in the world. Oral cancer represents 14% of all cancer cases in Kerala. The aim of this study is to find out the aetiological factors, symptomatology, morphologic types and the distribution in the sub-sites of oral cavity. MATERIALS AND METHODS A cross-sectional study was conducted in the Department of ENT, Government Medical College, Thrissur, Kerala from May 2009 to October 2013; 136 patients (88 males and 48 females with histopathologically confirmed oral cancers were studied. Variables such as age, sex, residing area, occupation, educational level, socio-economic status, substance abuse, oral hygiene, family history and premalignant conditions were assessed. The presenting complaints, the site, morphology and histopathology of the lesions were noted. RESULTS Mean age in this study was 57.83 with male-to-female ratio of 1.83:1. Majority of cases were from socially and economically weaker section, 62% patients were smokers, 45% patients were alcoholic, 41% patients were pan chewers and 90% had more than one bad habit; 72.05% patients had poor orodental hygiene. Most common symptom in our patients was growth in the mouth. Tongue and buccal mucosa were the most affected sites. Majority presented with ulcerative type and most of the cases were squamous cell carcinoma. CONCLUSION Oral cancers are mainly seen in males of 55 – 64 years’ age group. Important aetiological factors identified in this study are substance abuse, poor oral hygiene and poor socio-economic status. Tobacco consumption is the most dominant risk factor. Most common symptom in our patients is growth in the mouth. Tongue and buccal mucosa are the most affected sites. Most of the cases were squamous cell carcinoma. The study of aetiology and common clinical presentations may help in prevention, early detection and management.

Role of medical history and medication use in the aetiology of upper aerodigestive tract cancers in Europe: the ARCAGE study.

LENUS (Irish Health Repository)

Macfarlane, T V

2012-04-01

The study aimed to investigate the role of medical history (skin warts, Candida albicans, herpetic lesions, heartburn, regurgitation) and medication use (for heartburn; for regurgitation; aspirin) in the aetiology of upper aerodigestive tract (UADT) cancer.

Overview of Evidence in Prevention and Aetiology of Food Allergy: A Review of Systematic Reviews

Science.gov (United States)

Lodge, Caroline J.; Allen, Katrina J.; Lowe, Adrian J.; Dharmage, Shyamali C.

2013-01-01

The worldwide prevalence of food allergy appears to be increasing. Early life environmental factors are implicated in the aetiology of this global epidemic. The largest burden of disease is in early childhood, where research efforts aimed at prevention have been focused. Evidence synthesis from good quality systematic reviews is needed. We performed an overview of systematic reviews concerning the prevention and aetiology of food allergy, retrieving 14 systematic reviews, which covered three broad topics: formula (hydrolysed or soy) for the prevention of food allergy or food sensitization; maternal and infant diet and dietary supplements for the prevention of food allergy or food sensitization and hygiene hypothesis-related interventions. Using the AMSTAR criteria for assessment of methodological quality, we found five reviews to be of high quality, seven of medium quality and two of low quality. Overall we found no compelling evidence that any of the interventions that had been systematically reviewed were related to the risk of food allergy. Updating of existing reviews, and production of new systematic reviews, are needed in areas where evidence is emerging for interventions and environmental associations. Furthermore, additional primary studies, with greater numbers of participants and objective food allergy definitions are urgently required. PMID:24192789

Perspectives on aetiology, pathophysiology and management of shock in African children

Directory of Open Access Journals (Sweden)

Julius Nteziyaremye

Full Text Available Paediatric shock is still a common emergency of public health importance with an estimated 400,000–500,000 reported cases annually. Mortality due to paediatric shock has varied over the years. Data in 1980s show that mortality rates due to septic shock in children were over 50%; but by the end of the year 2000 data indicated that though a marked decline in mortality rates had been achieved, it had stagnated at about 20%. Descriptions of paediatric shock reveal the lack of a common definition and there are important gaps in evidence-based management in different settings. In well-resourced healthcare systems with well-functioning intensive care facilities, the widespread implementation of shock management guidelines based on the Paediatric Advanced Life Support and European Paediatric Advanced Life Support courses have reduced mortality. In resource limited settings with diverse infectious causative agents, the Emergency Triage Assessment and Treatment (ETAT approach is more pragmatic, but its impact remains circumscribed to centres where ETAT has been implemented and sustained. Advocacy for common management pathways irrespective of underlying cause have been suggested. However, in sub Saharan Africa, the diversity of underlying causative organisms and patient phenotypes may limit a single approach to shock management.Data from a large fluid trial (the FEAST trial in East Africa have provided vital insight to shock management. In this trial febrile children with clinical features of impaired perfusion were studied. Rapid infusion of fluid boluses, irrespective of whether the fluid was colloid or crystalloid, when compared to maintenance fluids alone had an increased risk of mortality at 48 h. All study participants were promptly managed for underlying conditions and comorbidity such as malaria, bacteraemia, severe anaemia, meningitis, pneumonia, convulsions, hypoglycaemia and others. The overall low mortality in the trial suggests the

Mechanical behavior of silicon carbide nanoparticles under uniaxial compression

Energy Technology Data Exchange (ETDEWEB)

He, Qiuxiang; Fei, Jing; Tang, Chao; Zhong, Jianxin; Meng, Lijun, E-mail: ljmeng@xtu.edu.cn [Xiangtan University, Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, Faculty of School of Physics and Optoelectronics (China)

2016-03-15

The mechanical behavior of SiC nanoparticles under uniaxial compression was investigated using an atomic-level compression simulation technique. The results revealed that the mechanical deformation of SiC nanocrystals is highly dependent on compression orientation, particle size, and temperature. A structural transformation from the original zinc-blende to a rock-salt phase is identified for SiC nanoparticles compressed along the [001] direction at low temperature. However, the rock-salt phase is not observed for SiC nanoparticles compressed along the [110] and [111] directions irrespective of size and temperature. The high-pressure-generated rock-salt phase strongly affects the mechanical behavior of the nanoparticles, including their hardness and deformation process. The hardness of [001]-compressed nanoparticles decreases monotonically as their size increases, different from that of [110] and [111]-compressed nanoparticles, which reaches a maximal value at a critical size and then decreases. Additionally, a temperature-dependent mechanical response was observed for all simulated SiC nanoparticles regardless of compression orientation and size. Interestingly, the hardness of SiC nanocrystals with a diameter of 8 nm compressed in [001]-orientation undergoes a steep decrease at 0.1–200 K and then a gradual decline from 250 to 1500 K. This trend can be attributed to different deformation mechanisms related to phase transformation and dislocations. Our results will be useful for practical applications of SiC nanoparticles under high pressure.

Has the aetiology of ischaemic stroke changed in the past decades? Analysis and comparison of data from current and historical stroke databases.

Science.gov (United States)

Sánchez-Larsen, Á; García-García, J; Ayo-Martín, O; Hernández-Fernández, F; Díaz-Maroto, I; Fernández-Díaz, E; Monteagudo, M; Segura, T

2016-09-16

We aimed to determine whether the aetiology of ischaemic stroke has changed in recent years and, if so, to ascertain the possible reasons for these changes. We analysed the epidemiological history and vascular risk factors of all patients diagnosed with ischaemic stroke at Complejo Hospitalario Universitario de Albacete (CHUA) from 2009 to 2014. Ischaemic stroke subtypes were established using the TOAST criteria. Our results were compared to data from the classic Stroke Data Bank (SDB); in addition, both series were compared to those of other hospital databases covering the period between the two. We analysed 1664 patients (58% were men) with a mean age of 74 years. Stroke aetiology in both series (CHUA, SDB) was as follows: atherosclerosis (12%, 9%), small-vessel occlusion (13%, 25%), cardioembolism (32%, 19%), stroke of other determined aetiology (3%, 4%), and stroke of undetermined aetiology (40%, 44%). Sixty-three percent of the patients from the CHUA and 42% of the patients from the SDB were older than 70 years. Cardioembolic strokes were more prevalent in patients older than 70 years in both series. Untreated hypertension was more frequent in the SDB (SDB = 31% vs CHUA = 10%). The analysis of other databases shows that the prevalence of cardioembolic stroke is increasing worldwide. Our data show that the prevalence of lacunar strokes is decreasing worldwide whereas cardioembolic strokes are increasingly more frequent in both our hospital and other series compared to the SDB. These differences may be explained by population ageing and the improvements in management of hypertension and detection of cardioembolic arrhythmias in stroke units. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

Changing trends over the last decade in the aetiology of childhood blindness: a study from a tertiary referral centre.

Science.gov (United States)

Ozturk, Taylan; Er, Duygu; Yaman, Aylin; Berk, A Tulin

2016-02-01

To discern treatable and preventable causes of childhood blindness by evaluating the aetiologic factors, and to compare the distribution of the most commonly affected anatomic sites of severe visual impairment (SVI) with our previous published data. The charts of 11 871 patients followed between June 2002 and May 2014 were reviewed retrospectively, and 695 patients (5.9%) who had SVI or blindness in accordance with WHO criteria were enrolled. The results of ophthalmologic examinations and coexistence of any systemic disease were documented and checked against our published clinic data concerning the aetiology of childhood blindness before 2002. χ(2) test was used for statistics. Mean age was 47.0±51.9 months (median: 24 months). Cortical visual impairment (CVI) was present in 212 cases (30.5%) and 20.3% of those had a history of premature birth. The most common anatomic sites of SVI were retina (24.6%) and crystalline lens (17.1%). When compared with our previous data, we found a significant increase in the prevalence of CVI (p=0.046) and decrease in the frequency of SVI due to uveal disorders (pblindness secondary to retinopathy of prematurity reduced by a third (p=0.280), and a significant decrease in aphakia-related SVI (p=0.028) was achieved within the last decade. The prevalence of CVI was found to be relatively increased due to the significant reduction in the frequency of preventable causes of SVI. Furthermore our clinical practice for visual rehabilitation in aphakia has resulted in a considerable decrease in SVI in the last decade. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Retracted: Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre.

Science.gov (United States)

Chauhan, V; Dada, R; Jain, V

2017-11-01

Retraction: 'Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre' by Vasundhera Chauhan, Rima Dada, Vandana Jain The above article, published online on 8 August 2016 in Wiley Online Library (http://wileyonlinelibrary.com), has been retracted by agreement between the authors, the Journal Editors-in-Chief, Wolf-Bernhard Schill and Ralf Henkel, and Blackwell Verlag GmbH. The retraction has been agreed as the result of an unresolved dispute between the first author and a colleague research fellow due to the inclusion of data from patients who were simultaneously enrolled in two studies being conducted separately by the two parties. Reference Chauhan, V., Dada, R. and Jain, V. (2016), Aetiology and clinical profile of children with 46, XY differences of sex development at an Indian referral centre. Andrologia. doi:10.1111/and.12663. © 2016 Blackwell Verlag GmbH.

Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation

KAUST Repository

Saghir, Shahid

2016-01-01

The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear

Peripheral Receptor Mechanisms Underlying Orofacial Muscle Pain and Hyperalgesia

Science.gov (United States)

Saloman, Jami L.

Musculoskeletal pain conditions, particularly those associated with temporomandibular joint and muscle disorders (TMD) are severely debilitating and affect approximately 12% of the population. Identifying peripheral nociceptive mechanisms underlying mechanical hyperalgesia, a prominent feature of persistent muscle pain, could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. This study provides evidence of functional interactions between ligand-gated channels, P2X3 and TRPV1/TRPA1, in trigeminal sensory neurons, and proposes that these interactions underlie the development of mechanical hyperalgesia. In the masseter muscle, direct P2X3 activation, via the selective agonist αβmeATP, induced a dose- and time-dependent hyperalgesia. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810, or the TRPA1 antagonist, AP18. P2X3 was co-expressed with both TRPV1 and TRPA1 in masseter muscle afferents confirming the possibility for intracellular interactions. Moreover, in a subpopulation of P2X3 /TRPV1 positive neurons, capsaicin-induced Ca2+ transients were significantly potentiated following P2X3 activation. Inhibition of Ca2+-dependent kinases, PKC and CaMKII, prevented P2X3-mechanical hyperalgesia whereas blockade of Ca2+-independent PKA did not. Finally, activation of P2X3 induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal sensory neurons. Significant phosphorylation was observed at 15 minutes, the time point at which behavioral hyperalgesia was prominent. Similar data were obtained regarding another nonselective cation channel, the NMDA receptor (NMDAR). Our data propose P2X3 and NMDARs interact with TRPV1 in a facilitatory manner, which could contribute to the peripheral sensitization underlying masseter hyperalgesia. This study offers novel mechanisms by which individual pro-nociceptive ligand

[Stroke in young adults: incidence and clinical picture in 280 patients according to their aetiological subtype].

Science.gov (United States)

Arboix, Adrià; Massons, Joan; García-Eroles, Luís; Oliveres, Montserrat

2016-03-04

To assess the clinical features and incidence rate of stroke in young adults (less than 55 years of age). Hospital-based descriptive study of 280 young inpatients consecutively admitted for stroke over a period of 24 years. We conducted a comparison with the remaining 4,312 patients admitted for stroke. Stroke in young adults represented 6.1% of all strokes, 5.7% of transient ischaemic attacks, 5.8% of cerebral infarctions and 8.4% of brain haemorrhages. However, reported minimal frequency of cardioembolic (2.1%) and atherothrombotic (3.4%) infarctions, accounted for 5.9% of lacunar and for 10.7% of essential infarctions and showed a maximum frequency in those infarctions of unusual aetiology (36%). Factors independently associated with stroke in young adults were cigarette smoking (OR 4.23; 95% CI 3.02-5.93; P=.000), unusual aetiology (OR 4.97; 95% CI 3.15-7.84; P=.000), headache (OR 4.57; 95% CI 2.59-8.07; P=.000), alcohol abuse (OR 3.93; 95% CI 2.46-6.29; P=.000), oral contraceptives (OR 14.07; 95% CI 2.37-83.40; P=.004), atrial fibrillation (OR 0.15; 95% CI 0.08-0.28; P=.000), arterial hypertension (OR 0.43; 95% CI 0.33-0.57; P=.000), COPD (OR 0.20; 95% CI 0.09-0.44; P=.000), atherothrombotic infarction (OR 0.51; 95% CI 0.34-0.77; P=.001), female sex (OR 0.71; 95% CI 0.52-0.97; P=.029), diabetes mellitus (OR 0.66; 95% CI 0.46-0.98; P=.030), ischaemic heart disease (OR 0.56; 95% CI 0.33-0.95; P=.032) and intermittent claudication (OR 0.48; 95% CI 0.24-0.94; P=.033). Stroke in young adults is infrequent (6.1% of the total), but represents the highest frequency of cerebral infarcts of unusual aetiology (36%). We conclude that stroke in younger patients presents its own and differentiated clinical profile. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

Underlying mechanisms of improving physical activity behavior after rehabilitation

NARCIS (Netherlands)

van der Ploeg, H.P.; Streppel, K.R.; van der Beek, A.J.; van der Woude, L.H.V.; van Harten, W.H.; van Mechelen, W.

2008-01-01

Background: Regular physical activity is beneficial for the health and functioning of people with a disability. Effective components of successful physical activity promotion interventions should be identified and disseminated. Purpose: To study the underlying mechanisms of the combined sport

Underlying Mechanisms of Improving Physical Activity Behavior after Rehabilitation

NARCIS (Netherlands)

van der Ploeg, Hidde P.; Streppel, Kitty R.M.; van der Beek, Allard J.; Woude, Luc H.V.; van Harten, Willem H.; Vollenbroek-Hutten, Miriam Marie Rosé; van Mechelen, Willem

2008-01-01

Background: Regular physical activity is beneficial for the health and functioning of people with a disability. Effective components of successful physical activity promotion interventions should be identified and disseminated. Purpose: To study the underlying mechanisms of the combined sport

On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

International Nuclear Information System (INIS)

Huang, Qiuyan; Pan, Hucheng; Tang, Aitao; Ren, Yuping; Song, Bo; Qin, Gaowu; Zhang, Mingxing; Pan, Fusheng

2016-01-01

To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10"−"3–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

On the dynamic mechanical property and deformation mechanism of as-extruded Mg-Sn-Ca alloys under tension

Energy Technology Data Exchange (ETDEWEB)

Huang, Qiuyan [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Pan, Hucheng [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Tang, Aitao, E-mail: tat@cqu.edu.cn [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China); Ren, Yuping [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Song, Bo [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Qin, Gaowu, E-mail: qingw@smm.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Zhang, Mingxing [School of Mechanical and Mining Engineering, University of Queensland, St Lucia, QLD 4072 (Australia); Pan, Fusheng [National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044 (China)

2016-05-10

To further understand the deformation mechanism of magnesium alloys and expand their applications under dynamic conditions, the newly developed Mg-2Sn-1Ca alloy (TX21) is selected as the representative sample and tested under wide loading rate ranging from quasi-static to dynamic level (10{sup −3}–500/s). Both ultimate tensile strength and elongation of the as-extruded TX21 alloys increase with strain rate. Although twinning is accompanied due to the enhanced activity at higher strain rate, the preferential activation of dislocations is readily clarified and confirmed as the dominant deformation modes. Active interactions of pyramidal dislocations result in the higher strain hardening ability and could be correlated to the obviously positive strain-rate sensitivity for mechanical properties. Moreover, it is observed that the larger grain size and higher content of solute atoms dissolved in matrix would lead to the more active dislocations and twinning formations. The present results would provide insight into further understanding the deformation mechanism under dynamic rate loading and designing Mg alloy suitable for impact conditions.

Animal behavior models of the mechanisms underlying antipsychotic atypicality.

NARCIS (Netherlands)

Geyer, M.A.; Ellenbroek, B.A.

2003-01-01

This review describes the animal behavior models that provide insight into the mechanisms underlying the critical differences between the actions of typical vs. atypical antipsychotic drugs. Although many of these models are capable of differentiating between antipsychotic and other psychotropic

Molecular mechanisms underlying the emergence of bacterial pathogens: an ecological perspective.

Science.gov (United States)

Bartoli, Claudia; Roux, Fabrice; Lamichhane, Jay Ram

2016-02-01

The rapid emergence of new bacterial diseases negatively affects both human health and agricultural productivity. Although the molecular mechanisms underlying these disease emergences are shared between human- and plant-pathogenic bacteria, not much effort has been made to date to understand disease emergences caused by plant-pathogenic bacteria. In particular, there is a paucity of information in the literature on the role of environmental habitats in which plant-pathogenic bacteria evolve and on the stress factors to which these microbes are unceasingly exposed. In this microreview, we focus on three molecular mechanisms underlying pathogenicity in bacteria, namely mutations, genomic rearrangements and the acquisition of new DNA sequences through horizontal gene transfer (HGT). We briefly discuss the role of these mechanisms in bacterial disease emergence and elucidate how the environment can influence the occurrence and regulation of these molecular mechanisms by directly impacting disease emergence. The understanding of such molecular evolutionary mechanisms and their environmental drivers will represent an important step towards predicting bacterial disease emergence and developing sustainable management strategies for crops. © 2015 BSPP AND JOHN WILEY & SONS LTD.

The Influence of Circadian Variation on Aetiological Markers of Ankle Injury.

Science.gov (United States)

Brogden, Chris; Marrin, Kelly; Page, Richard; Greig, Matt

2018-03-15

Clinical and functional assessments are performed regularly in sporting environments to screen for performance deficits and injury risk. Circadian rhythms have been demonstrated to affect human performance, however the influence of time of day on a battery of multiple ankle injury risk factors has yet to be established within athletic populations. To investigate the influence of circadian variation on a battery of tests, used to screen for ankle aetiological risk factors. Randomised crossover design. University laboratory. Thirty-three semi-professional soccer players (age 24.9 ± 4.4 years; height 1.77 ± 0.17 m; body mass 75.47 ± 7.98 kg) completed three randomized experimental trials (07:00 h, 12:00 h, 19:00 h) Main Outcome Measures: Trials involved the completion of a standardized test battery comprising Biodex Stability System (BSS), Star Excursion Balance Test (SEBT), isokinetic inversion: eversion ratio, joint position sense, and a drop landing inversion cutting manoeuvre. Repeated measures analysis of variance revealed significantly (P < 0.05) lower values for all BSS indicia; Overall Stability Index (1.10 ± 0.31 a.u), Anterior-Posterior (0.76 ± 0.21 a.u) and Medio-Lateral (0.68 ± 0.23) at 12:00 h when compared to 07:00 h. (1.30 ± 0.45 a.u; 0.96 ± 0.26 a.u; 0.82 ± 0.40 a.u) respectively. However, no significant (P ≥ 0.05) main effects for time of day were reported for any other test. Circadian influence on ankle aetiological risk factors was task dependent, with measures of proprioception, strength and SEBT displaying no circadian variation, indicating no association between time of day and markers of injury risk. However, the BSS displayed improved performance at midday, indicating postural stability tasks requiring unanticipated movements to display a time of day effect and potential increased injury risk. Consequently, time of testing for this task should be standardized to ensure correct interpretations of assessments and/or interventions.

Aetiology of Vertigo as Seen at the Federal Medical Center Lokoja, North Central Nigeria

Directory of Open Access Journals (Sweden)

Stephen Agbomhekhe Ogah

2017-05-01

Results: Three thousand two hundred and fourteen patients were seen and 65 of them had vertigo with a prevalence of 2.0%. Fifteen files had incomplete information and were not include in the study. The remaining 50 patients' files that were reviewed, consisted of 32 males (64% and 18 females (36%. Male to female ratio was 1.8:1 and a mean age of 24.8 years. Bengin Paroxysmal Positional Vertigo (BPPV 22(44% was the commonest aetiology found followed by Meniere's disease 8(16%, trauma 7(14% and Vestibular Neuronitis 5(10% respectively.

The aetiology of oral submucous fibrosis: the stimulation of collagen synthesis by extracts of areca nut.

Science.gov (United States)

Canniff, J P; Harvey, W

1981-01-01

Oral submucous fibrosis is a chronic disabling disease developing in up to 0.5% of the estimated 500 million habitual chewers of the "betel" quid. The quid, or chew, usually comprises a leaf of the Piper betel vine in which is wrapped fragments of the nut of Areca catechu, together with slaked lime and varied additives, including tobacco. The precise aetiology of oral submucous fibrosis (OSF) remains obscure, but epidemiological and animal studies have pointed to a close association with the prolonged usage of A. catechu nuts. Epithelial atypia and epidermoid carcinoma have been reported in 15% and 7%, respectively, of patients with established OSF. Preparations from varieties of A. catechu nuts have been tested for their ability to stimulate collagen synthesis in microwell cultures of human fibroblasts, using a pulse of 3H-proline and subsequent analysis of the cultures for radioactive collagen. Crude extracts of three varieties of areca nuts were extracted with ethanol and lyophilised before dilution in the culture medium. Control media contained identical concentrations of ethanol where appropriate. The three extracts at a concentration of 10 micrograms/ml stimulated collagen synthesis by approximately 150%, suggesting that this effect might be involved in the aetiology of oral submucous fibrosis.

Churg-Strauss Syndrome as an Unusual Aetiology of Stroke with Haemorrhagic Transformation in a Patient with No Cardiovascular Risk Factors

Directory of Open Access Journals (Sweden)

Tiina Sairanen

2011-01-01

Full Text Available Background: We present here a case of haemorrhagic brain infarction in a middle-aged and physically active male, who had never smoked. This case report aims to remind the internist and neurologist to bear in mind unusual aetiologies of brain infarcts in patients without classical cardiovascular risk factors. Case Description: A 49-year-old male with pulmonary asthma and a prior history of nasal polyps had a wake-up stroke with left-sided symptoms and speech disturbance. A head MRI and MR angiography revealed a recent haemorrhagic infarct in the right putamen and corona radiata. The left hemiparesis progressed to sensory-motor hemiplegia on the 4th day. In the head CT, it was shown that the haemorrhagic infarct had progressed to a large haematoma. A pansinusitis was also diagnosed. The aetiological investigations revealed a minor atrial septal defect (ASD with shunting and a heterozygotic clotting factor V R506Q mutation. A remarkable blood eosinophilia of 9.80 E9/l (42% together with fever, sinusitis, wide-spread bilateral nodular pulmonary infiltrates that did not respond to wide-spectrum antimicrobial treatment, positive anti-neutrophilic cytoplasmic antibodies, a high myeloperoxidase antibody level and slightly positive anti-proteinase 3 antibodies suggested the diagnosis of Churg-Strauss syndrome. These inflammatory symptoms and findings promptly responded to treatment with corticosteroids and cyclophosphamide. Conclusions: Even after the concomitant findings of the low risk factors, i.e. small ASD and heterozygotic clotting factor mutation, continued search for the final aetiology of stroke revealed Churg-Strauss syndrome, which was the key to the treatment.

Churg-Strauss Syndrome as an Unusual Aetiology of Stroke with Haemorrhagic Transformation in a Patient with No Cardiovascular Risk Factors

Science.gov (United States)

Sairanen, Tiina; Kanerva, Mari; Valanne, Leena; Lyytinen, Jukka; Pekkonen, Eero

2011-01-01

Background We present here a case of haemorrhagic brain infarction in a middle-aged and physically active male, who had never smoked. This case report aims to remind the internist and neurologist to bear in mind unusual aetiologies of brain infarcts in patients without classical cardiovascular risk factors. Case Description A 49-year-old male with pulmonary asthma and a prior history of nasal polyps had a wake-up stroke with left-sided symptoms and speech disturbance. A head MRI and MR angiography revealed a recent haemorrhagic infarct in the right putamen and corona radiata. The left hemiparesis progressed to sensory-motor hemiplegia on the 4th day. In the head CT, it was shown that the haemorrhagic infarct had progressed to a large haematoma. A pansinusitis was also diagnosed. The aetiological investigations revealed a minor atrial septal defect (ASD) with shunting and a heterozygotic clotting factor V R506Q mutation. A remarkable blood eosinophilia of 9.80 E9/l (42%) together with fever, sinusitis, wide-spread bilateral nodular pulmonary infiltrates that did not respond to wide-spectrum antimicrobial treatment, positive anti-neutrophilic cytoplasmic antibodies, a high myeloperoxidase antibody level and slightly positive anti-proteinase 3 antibodies suggested the diagnosis of Churg-Strauss syndrome. These inflammatory symptoms and findings promptly responded to treatment with corticosteroids and cyclophosphamide. Conclusions Even after the concomitant findings of the low risk factors, i.e. small ASD and heterozygotic clotting factor mutation, continued search for the final aetiology of stroke revealed Churg-Strauss syndrome, which was the key to the treatment. PMID:21468361

Novel urinary biomarkers and their association with urinary heavy metals in chronic kidney disease of unknown aetiology in Sri Lanka: a pilot study

Science.gov (United States)

Wanigasuriya, K; Jayawardene, I; Amarasiriwardena, C; Wickremasinghe, R

2017-12-26

Chronic kidney disease of unknown etiology (CKDu) has emerged as a significant public health problem in Sri Lanka. The role of environmental exposure to cadmium and arsenic in the aetiology of CKDu is still unclear. Identification of a panel of novel urinary biomarkers would be invaluable in the study of toxin mediated damage postulated to be the aetiology of CKDu. The aims of this study were to evaluate the profile of novel urinary biomarkers in CKDu patients and identify any association with environmental exposure to heavy metals. Thirty seven randomly selected CKDu patients attending a renal clinic in the North Central Province and two control groups namely a farmer group (n=39) and a non-farmer group (n=40) from a non-endemic area were included in this comparative cross sectional study. Urine samples were analyzed for heavy metals and five urinary biomarkers. CKDu patients had significantly elevated urinary levels of fibrinogen (198.2 ng/mg creatinine pCKDu patients from normal individuals with the receiver operator areas under the curve being 0.867 and 0.853, respectively. Urinary fibrinogen and KIM-1 levels correlated positively with urinary arsenic levels. KIM-1 levels correlated positively with urinary mercury and lead levels but no correlation was seen with urinary cadmium levels. Fibrinogen and β2-microglobulin have the potential of being a screening tool for detection of CKDu and may aid the early diagnosis of toxin mediated tubular injury in CKDu. Their usefulness need to be further validated in a larger epidemiological study of patients with early stages of CKDu.

A systematic review of personality disorder, race and ethnicity: prevalence, aetiology and treatment

Directory of Open Access Journals (Sweden)

Lee Tennyson

2010-05-01

Full Text Available Abstract Background Although psychoses and ethnicity are well researched, the importance of culture, race and ethnicity has been overlooked in Personality Disorders (PD research. This study aimed to review the published literature on ethnic variations of prevalence, aetiology and treatment of PD. Method A systematic review of studies of PD and race, culture and ethnicity including a narrative synthesis of observational data and meta-analyses of prevalence data with tests for heterogeneity. Results There were few studies with original data on personality disorder and ethnicity. Studies varied in their classification of ethnic group, and few studies defined a specific type of personality disorder. Overall, meta-analyses revealed significant differences in prevalence between black and white groups (OR 0.476, CIs 0.248 - 0.915, p = 0.026 but no differences between Asian or Hispanic groups compared with white groups. Meta-regression analyses found that heterogeneity was explained by some study characteristics: a lower prevalence of PD was reported among black compared with white patients in UK studies, studies using case-note diagnoses rather than structured diagnostic interviews, studies of borderline PD compared with the other PD, studies in secure and inpatient compared with community settings, and among subjects with co-morbid disorders compared to the rest. The evidence base on aetiology and treatment was small. Conclusion There is some evidence of ethnic variations in prevalence of personality disorder but methodological characteristics are likely to account for some of the variation. The findings may indicate neglect of PD diagnosis among ethnic groups, or a true lower prevalence amongst black patients. Further studies are required using more precise cultural and ethnic groups.

Aetiology and severity of gingival recession in an adult population sample in Greece

Directory of Open Access Journals (Sweden)

Nikolaos Andreas Chrysanthakopoulos

2011-01-01

Full Text Available Background: Gingival recession is the most common and undesirable condition of the gingiva. The aim of study was to investigate the aetiology and severity of gingival recession in a Greek adult population sample. Methods : The study was performed on 165 males and 179 females, 18-68 years old who sought dental treatment in a private dental practice and showed gingival recession. All subjects were clinically examined and answered questions regarding their oral hygiene habits such as the type of toothbrush, frequency of brushing and method of brushing. The association between gingival recession and the following parameters was assessed: plaque score, gingival score and tooth position. Statistical analysis of the results was accomplished using chi-square test (α = 0.05. Results: The majority (79.4% of the patients showed grade I gingival recession and 15.3% showed grade II gingival recession. The maxillary 1 st and 2 nd molars (35.3% and the mandibular 1 st and 2 nd molars (28.7% were the teeth most frequently affected by root surface exposure. Patients with sub-gingival calculus, bacterial plaque and gingival inflammation (P < 0.05, malpositioned teeth (P < 0.001, horizontal brushing method, medium type of toothbrush (P < 0.001 and brushing once daily (P < 0.001 appeared to be the most common precipitating aetiological factor for gingival recession. Conclusion: According to the results of the present study, gingival recession was the result of more than one factor acting together. Horizontal brushing method, usage of medium type toothbrush and tooth brushing once daily were found to be more associated with gingival recession.

A systematic review of personality disorder, race and ethnicity: prevalence, aetiology and treatment.

Science.gov (United States)

McGilloway, Angela; Hall, Ruth E; Lee, Tennyson; Bhui, Kamaldeep S

2010-05-11

Although psychoses and ethnicity are well researched, the importance of culture, race and ethnicity has been overlooked in Personality Disorders (PD) research. This study aimed to review the published literature on ethnic variations of prevalence, aetiology and treatment of PD. A systematic review of studies of PD and race, culture and ethnicity including a narrative synthesis of observational data and meta-analyses of prevalence data with tests for heterogeneity. There were few studies with original data on personality disorder and ethnicity. Studies varied in their classification of ethnic group, and few studies defined a specific type of personality disorder. Overall, meta-analyses revealed significant differences in prevalence between black and white groups (OR 0.476, CIs 0.248 - 0.915, p = 0.026) but no differences between Asian or Hispanic groups compared with white groups. Meta-regression analyses found that heterogeneity was explained by some study characteristics: a lower prevalence of PD was reported among black compared with white patients in UK studies, studies using case-note diagnoses rather than structured diagnostic interviews, studies of borderline PD compared with the other PD, studies in secure and inpatient compared with community settings, and among subjects with co-morbid disorders compared to the rest. The evidence base on aetiology and treatment was small. There is some evidence of ethnic variations in prevalence of personality disorder but methodological characteristics are likely to account for some of the variation. The findings may indicate neglect of PD diagnosis among ethnic groups, or a true lower prevalence amongst black patients. Further studies are required using more precise cultural and ethnic groups.

Mechanisms underlying UV-induced immune suppression

International Nuclear Information System (INIS)

Ullrich, Stephen E.

2005-01-01

Skin cancer is the most prevalent form of human neoplasia. Estimates suggest that in excess of one million new cases of skin cancer will be diagnosed this year alone in the United States (www.cancer.org/statistics). Fortunately, because of their highly visible location, skin cancers are more rapidly diagnosed and more easily treated than other types of cancer. Be that as it may, approximately 10,000 Americans a year die from skin cancer. The cost of treating non-melanoma skin cancer is estimated to be in excess of US$ 650 million a year [J.G. Chen, A.B. Fleischer, E.D. Smith, C. Kancler, N.D. Goldman, P.M. Williford, S.R. Feldman, Cost of non-melanoma skin cancer treatment in the United States, Dermatol. Surg. 27 (2001) 1035-1038], and when melanoma is included, the estimated cost of treating skin cancer in the United States is estimated to rise to US$ 2.9 billion annually (www.cancer.org/statistics). Because the morbidity and mortality associated with skin cancer is a major public health problem, it is important to understand the mechanisms underlying skin cancer development. The primary cause of skin cancer is the ultraviolet (UV) radiation found in sunlight. In addition to its carcinogenic potential, UV radiation is also immune suppressive. In fact, data from studies with both experimental animals and biopsy proven skin cancer patients suggest that there is an association between the immune suppressive effects of UV radiation and its carcinogenic potential. The focus of this manuscript will be to review the mechanisms underlying the induction of immune suppression following UV exposure. Particular attention will be directed to the role of soluble mediators in activating immune suppression

Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity

Science.gov (United States)

2017-10-01

AWARD NUMBER: W81XWH-16-1-0652 TITLE: Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity PRINCIPAL INVESTIGATOR...5a. CONTRACT NUMBER W81XWH-16-1-0652 Mechanisms Underlying Stress Fracture and the Influence of Sex and Race/Ethnicity 5b. GRANT NUMBER W81XWH...to stress fracture risk. In particular, in Study 1, we will perform advanced skeletal imaging along with gait-assessments in subjects with history of

Failure Mechanisms of Brittle Rocks under Uniaxial Compression

Science.gov (United States)

Liu, Taoying; Cao, Ping

2017-09-01

The behaviour of a rock mass is determined not only by the properties of the rock matrix, but mostly by the presence and properties of discontinuities or fractures within the mass. The compression test on rock-like specimens with two prefabricated transfixion fissures, made by pulling out the embedded metal inserts in the pre-cured period was carried out on the servo control uniaxial loading tester. The influence of the geometry of pre-existing cracks on the cracking processes was analysed with reference to the experimental observation of crack initiation and propagation from pre-existing flaws. Based on the rock fracture mechanics and the stress-strain curves, the evolution failure mechanism of the fissure body was also analyzed on the basis of exploring the law of the compression-shear crack initiation, wing crack growth and rock bridge connection. Meanwhile, damage fracture mechanical models of a compression-shear rock mass are established when the rock bridge axial transfixion failure, tension-shear combined failure, or wing crack shear connection failure occurs on the specimen under axial compression. This research was of significance in studying the failure mechanism of fractured rock mass.

Differences of psychological features in patients with heart failure with regard to gender and aetiology - Results of a CAPS-LOCK-HF (Complex Assessment of Psychological Status Located in Heart Failure) study.

Science.gov (United States)

Orszulak, Michal; Mizia-Stec, Katarzyna; Siennicka, Agnieszka; Goscinska-Bis, Kinga; Waga, Karolina; Wojcik, Maciej; Blaszczyk, Robert; Michalski, Blazej; Szymanski, Filip M; Ptaszynska-Kopczynska, Katarzyna; Kopec, Grzegorz; Nadrowski, Pawel; Hrynkiewicz-Szymanska, Anna; Krzych, Lukasz; Jankowska, Ewa A

2016-09-15

Objective of the study was to assess the psychological state of HF patients with reduced ejection fraction (HFrEF) with regard to gender and aetiology. 758 patients with HFrEF (mean age - 64±11years, men - 79%, NYHA class III-IV - 40%, ischemic aetiology - 61%) in a prospective Polish multicenter Caps-Lock-HF study. Scores on five different self-report inventories: CISS, MHLC, GSES, BDI and modified Mini-MAC were compared between the sexes taking into account the aetiology of HFrEF. There were differences in the CISS and BDI score between the genders - women had higher CISS (emotion- and avoidance-oriented) and BDI (general score - 14.2±8.7 vs 12.3±8.6, Ppsychological data made a significant additional contribution to the prediction of depression status. There are distinct differences in psychological features with regard to gender in patients with HFrEF. Women demonstrate less favourable psychological characteristics. Gender-related differences in BDI score are especially explicit in patients with ischemic aetiology of HF. The BDI score is related to psychological predisposition. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Bovine pododermatitis aseptica diffusa (laminitis) aetiology, pathogenesis, treatment and control.

Science.gov (United States)

Mgasa, M N

1987-01-01

Pododermatitis aseptica diffusa (laminitis) is a major cause of lameness and discomfort to cattle with resultant economic losses. The disease is a result of multifactorial aetiology most of which is not clearly understood. Feeding readily fermentable carbohydrates to unaccustomed cattle predisposes to the disease. Histamine, lactic acid and endotoxins are believed to be involved. Systemic acidosis, histaminosis and endotoxaemia are thought to produce the pathophysiological characteristics of laminitis. The diagnosis is primarily based on the observation of symmetrical and bilateral lesions in hooves and characteristic lameness affecting all feet. Gross lesions include concavity of the dorsal wall, discolorations in the sole and rotation of the pedal bone. Degenerative changes and arteriosclerosis are constant histological findings in the corium, with chronic thrombi and chronic granulation tissue. The disease may be treated conservatively and by application of cyclo-oxygenase inhibiting non-steroidal anti-inflammatory drugs and prevented or controlled by proper feeding and management practices.

Villitis of unknown aetiology: correlation of recurrence with clinical outcome.

LENUS (Irish Health Repository)

Feeley, L

2010-01-01

Villitis of unknown aetiology (VUA) is associated with adverse pregnancy outcome. Consequently, an ability to predict recurrence could be clinically relevant. We examined placentas where villitis was diagnosed in a previous pregnancy to establish the risk of recurrence and outcome. A total of 304 cases of VUA were diagnosed in our laboratory over a 4-year period. Subsequently, 19 of this cohort had a second placenta examined histologically. Recurrence and clinical outcome were recorded. Villitis recurred in 7 of 19 cases (37%). There was a high level of adverse pregnancy outcome in this cohort overall, characterised by small for gestational age infants and stillbirth, particularly in cases with high-grade villitis. We identified recurrent villitis more frequently than previously reported. Our findings confirm an association between high-grade villitis and poor outcome. Adequately powered prospective studies are required to determine if enhanced surveillance of subsequent pregnancies is indicated following a diagnosis of villitis.

Gifles de la Tourett's Disease a Single case study A Discussion on Aetiology and Treatment

Directory of Open Access Journals (Sweden)

C. Izadi

1978-06-01

Full Text Available A case of Gille de la Tourett's syndrome is reported and discussed 111 the light of conflicting views on the aetiology of the condition. It is hypothesized that if Tourette's syndrome is to be considered as a sort of reaction against adaption to an unhealthy environment, this reaction and its continuity can be attributed to permanent eNS damage (Probably in the area of corpora striata beginning in childhood. Treatment with haloperidol is suggested as a most effective method of symptomatic treatment.

The aetiology of post-traumatic stress following childbirth: a meta-analysis and theoretical framework.

Science.gov (United States)

Ayers, S; Bond, R; Bertullies, S; Wijma, K

2016-04-01

There is evidence that 3.17% of women report post-traumatic stress disorder (PTSD) after childbirth. This meta-analysis synthesizes research on vulnerability and risk factors for birth-related PTSD and refines a diathesis-stress model of its aetiology. Systematic searches were carried out on PsycINFO, PubMed, Scopus and Web of Science using PTSD terms crossed with childbirth terms. Studies were included if they reported primary research that examined factors associated with birth-related PTSD measured at least 1 month after birth. In all, 50 studies (n = 21 429) from 15 countries fulfilled inclusion criteria. Pre-birth vulnerability factors most strongly associated with PTSD were depression in pregnancy (r = 0.51), fear of childbirth (r = 0.41), poor health or complications in pregnancy (r = 0.38), and a history of PTSD (r = 0.39) and counselling for pregnancy or birth (r = 0.32). Risk factors in birth most strongly associated with PTSD were negative subjective birth experiences (r = 0.59), having an operative birth (assisted vaginal or caesarean, r = 0.48), lack of support (r = -0.38) and dissociation (r = 0.32). After birth, PTSD was associated with poor coping and stress (r = 0.30), and was highly co-morbid with depression (r = 0.60). Moderator analyses showed that the effect of poor health or complications in pregnancy was more apparent in high-risk samples. The results of this meta-analysis are used to update a diathesis-stress model of the aetiology of postpartum PTSD and can be used to inform screening, prevention and intervention in maternity care.

The prevalence, aetiology and management of wounds in a community care area in Ireland.

LENUS (Irish Health Repository)

Skerritt, Louise

2014-06-01

This study aimed to establish the prevalence and aetiology of wounds, allowing an insight into the management of wound care, the use of dressings and the nursing time allocated to the provision of wound care in a community setting in Ireland. A cross-sectional survey was used, with data collected on all clients in the community who received treatment from public health nurses or community registered general nurses for wound care over a 1-week period in April 2013. A 98.9% response rate was realised, and 188 people were identified as having wounds, equating to a crude prevalence of 5% of the active community nursing caseload. A total of 60% (n=112) had leg ulcers, 22% (n=42) had pressure ulcers, 16% (n=30) had an acute wound (surgical or traumatic wounds), 1% (n=2) had a diabetic foot wound and a further 1% (n=2) had wounds of other aetiologies. The mean duration of wounds was 5.41 months. A total of 18% of wounds were identified as infected; however, 60% (n=112) of wounds had antimicrobial products in use as either a primary or secondary dressing. The study established that there is a significant prevalence of wounds in this community care area. There was absence of a clinical diagnosis in many cases, and evidence of inappropriate dressing use, risking an increase in costs and a decrease in good clinical outcomes. It also highlighted the importance of ongoing education and auditing in the provision of wound care.

Cervicitis aetiology and case definition: a study in Australian women attending sexually transmitted infection clinics.

Science.gov (United States)

Lusk, M Josephine; Garden, Frances L; Rawlinson, William D; Naing, Zin W; Cumming, Robert G; Konecny, Pam

2016-05-01

Studies examining cervicitis aetiology and prevalence lack comparability due to varying criteria for cervicitis. We aimed to outline cervicitis associations and suggest a best case definition. A cross-sectional study of 558 women at three sexually transmitted infection clinics in Sydney, Australia, 2006-2010, examined pathogen and behavioural associations of cervicitis using three cervicitis definitions: 'microscopy' (>30 pmnl/hpf (polymorphonuclear leucocytes per high-powered field on cervical Gram stain)), 'cervical discharge' (yellow and/or mucopurulent cervical discharge) or 'micro+cervical discharge' (combined 'microscopy' and 'cervical discharge'). Chlamydia trachomatis (CT), Mycoplasma genitalium (MG), Trichomonas vaginalis (TV) and Neisseria gonorrhoeae (NG) had the strongest associations with cervicitis definitions 'micro+cervical discharge': CT adjusted prevalence ratio (APR)=2.13 (95% CI 1.38 to 3.30) p=0.0006, MG APR=2.21 (1.33 to 3.69) p=0.002, TV APR=2.37 (1.44 to 3.90) p=0.0007 NG PR=4.42 (3.79 to 5.15) pdefinitions with best clinical utility and pathogen prediction were 'cervical discharge' and 'micro+cervical discharge'. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Oral submucous fibrosis: an overview of the aetiology, pathogenesis, classification, and principles of management.

Science.gov (United States)

Arakeri, Gururaj; Brennan, Peter A

2013-10-01

Oral submucous fibrosis (OSMF) is a complex, debilitating, and precancerous condition. Formerly confined to the Indian subcontinent, it is now often seen in the Asian populations of the United Kingdom, USA, and other developed countries, and is therefore a serious problem for global health. The well-known causative agent of the disease, areca-nut is now recognised as a group one carcinogen. We review and discuss all components of OSMF, including the terminology, presentation, aetiology, and pathogenesis, and provide a brief overview of its management. Copyright © 2012 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Mechanisms Underlying the Antidepressant Response and Treatment Resistance

Directory of Open Access Journals (Sweden)

Marjorie Rose Levinstein

2014-06-01

Full Text Available Depression is a complex and heterogeneous disorder affecting millions of Americans. There are several different medications and other treatments that are available and effective for many patients with depression. However, a substantial percentage of patients fail to achieve remission with these currently available interventions, and relapse rates are high. Therefore, it is necessary to determine both the mechanisms underlying the antidepressant response and the differences between responders and non-responders to treatment. Delineation of these mechanisms largely relies on experiments that utilize animal models. Therefore, this review provides an overview of the various mouse models that are currently used to assess the antidepressant response, such as chronic mild stress, social defeat, and chronic corticosterone. We discuss how these mouse models can be used to advance our understanding of the differences between responders and non-responders to antidepressant treatment. We also provide an overview of experimental treatment modalities that are used for treatment-resistant depression, such as deep brain stimulation and ketamine administration. We will then review the various genetic polymorphisms and transgenic mice that display resistance to antidepressant treatment. Finally, we synthesize the published data to describe a potential neural circuit underlying the antidepressant response and treatment resistance.

Depression and Chronic Liver Diseases: Are There Shared Underlying Mechanisms?

Directory of Open Access Journals (Sweden)

Xiaoqin Huang

2017-05-01

Full Text Available The occurrence of depression is higher in patients with chronic liver disease (CLD than that in the general population. The mechanism described in previous studies mainly focused on inflammation and stress, which not only exists in CLD, but also emerges in common chronic diseases, leaving the specific mechanism unknown. This review was to summarize the prevalence and risk factors of depression in CLD including chronic hepatitis B, chronic hepatitis, alcoholic liver disease, and non-alcoholic fatty liver disease, and to point out the possible underlying mechanism of this potential link. Clarifying the origins of this common comorbidity (depression and CLD may provide more information to understand both diseases.

Mechanical Behavior of Shale Rock under Uniaxial Cyclic Loading and Unloading Condition

Directory of Open Access Journals (Sweden)

Baoyun Zhao

2018-01-01

Full Text Available In order to investigate the mechanical behavior of shale rock under cyclic loading and unloading condition, two kinds of incremental cyclic loading tests were conducted. Based on the result of the short-term uniaxial incremental cyclic loading test, the permanent residual strain, modulus, and damage evolution were analyzed firstly. Results showed that the relationship between the residual strains and the cycle number can be expressed by an exponential function. The deformation modulus E50 and elastic modulus ES first increased and then decreased with the peak stress under the loading condition, and both of them increased approximately linearly with the peak stress under the unloading condition. On the basis of the energy dissipation, the damage variables showed an exponential increasing with the strain at peak stress. The creep behavior of the shale rock was also analyzed. Results showed that there are obvious instantaneous strain, decay creep, and steady creep under each stress level and the specimen appears the accelerated creep stage under the 4th stress of 51.16 MPa. Based on the characteristics of the Burgers creep model, a viscoelastic-plastic creep model was proposed through viscoplastic mechanics, which agrees very well with the experimental results and can better describe the creep behavior of shale rock better than the Burgers creep model. Results can provide some mechanics reference evidence for shale gas development.

Vascular mechanisms underlying the hypotensive effect of Rumex acetosa.

Science.gov (United States)

Qamar, Hafiz Misbah-Ud-Din; Qayyum, Rahila; Salma, Umme; Khan, Shamim; Khan, Taous; Shah, Abdul Jabbar

2018-12-01

Rumex acetosa L. (Polygonaceae) is well known in traditional medicine for its therapeutic efficacy as an antihypertensive. The study investigates antihypertensive potential of crude methanol extract (Ra.Cr) and fractions of Rumex acetosa in normotensive and hypertensive rat models and probes the underlying vascular mechanisms. Ra.Cr and its fractions were tested in vivo on normotensive and hypertensive Sprague-Dawley rats under anaesthesia for blood pressure lowering effect. In vitro experiments on rat and Oryctolagus cuniculus rabbit aortae were employed to probe the underlying vasorelaxant mechanism. In normotensive rats under anaesthesia, Ra.Cr caused fall in MAP (40 mmHg) at 50 mg/kg with % fall of 27.88 ± 4.55. Among the fractions tested, aqueous fraction was more potent at the dose of 50 mg/kg with % fall of 45.63 ± 2.84. In hypertensive rats under similar conditions, extract and fractions showed antihypertensive effect at same doses while aqueous fraction being more potent, exhibited 68.53 ± 4.45% fall in MAP (70 mmHg). In isolated rat aortic rings precontracted with phenylephrine (PE), Ra.Cr and fractions induced endothelium-dependent vasorelaxation, which was partially blocked in presence of l-NAME, indomethacin and atropine. In isolated rabbit aortic rings pre-contracted with PE and K + -(80 mM), Ra.Cr induced vasorelaxation and shifted Ca 2+ concentration-response curves to the right and suppressed PE peak formation, similar to verapamil, in Ca 2+ -free medium. The data indicate that l-NAME and atropine-sensitive endothelial-derived NO and COX enzyme inhibitors and Ca 2+ entry blocking-mediated vasodilator effect of the extract explain its antihypertensive potential.

A possible realization of Einstein's causal theory underlying quantum mechanics

International Nuclear Information System (INIS)

Yussouff, M.

1979-06-01

It is shown that a new microscopic mechanics formulated earlier can be looked upon as a possible causal theory underlying quantum mechanics, which removes Einstein's famous objections against quantum theory. This approach is free from objections raised against Bohm's hidden variable theory and leads to a clear physical picture in terms of familiar concepts, if self interactions are held responsible for deviations from classical behaviour. The new level of physics unfolded by this approach may reveal novel frontiers in high-energy physics. (author)

Aetiologies of diarrhoea in adults from urban and rural treatment facilities in Bangladesh.

Science.gov (United States)

Ferdous, F; Ahmed, S; Farzana, F D; Das, J; Malek, M A; Das, S K; Salam, M A; Faruque, A S G

2015-05-01

The objective of our analysis was to describe the aetiology, clinical features, and socio-demographic background of adults with diarrhoea attending different urban and rural diarrhoeal disease hospitals in Bangladesh. Between January 2010 and December 2011, a total of 5054 adult diarrhoeal patients aged ⩾20 years were enrolled into the Diarrhoeal Disease Surveillance Systems at four different hospitals (two rural and two urban) of Bangladesh. Middle-aged [adjusted odds ratio (aOR) 0·28, 95% confidence interval (CI) 0·23-0·35, P economic and other progress made, conditions facilitating transmission of V. cholerae and Shigella prevail in adults with diarrhoea in Bangladesh and further efforts are needed to control these infections.

Twin studies as a model for exploring the aetiology of autoimmune thyroid disease

DEFF Research Database (Denmark)

Brix, Thomas Heiberg; Hegedüs, Laszlo

2012-01-01

Twins are an important resource for evaluating the relative contribution of genetic and environmental factors in determining a phenotype. During the last decades, a number of twin studies have investigated the aetiology of several phenotypes related to thyroid autoimmunity. Taken together, these ....... Future twin studies should incorporate information on genetic, epigenetic and environmental variation thereby enhancing our ability to quantify the precise effect of specific risk factors......., and biometric twin modelling shows that approximately 75% of the total phenotypic variance in AITD is because of genetic effects. On the other hand, the lack of complete concordance in MZ twin pairs is proof of environmental and/or epigenetic factors also playing an important role. The impact of environmental...

Cognitive mechanisms underlying disorganization of thought in a genetic syndrome (47,XXY)

NARCIS (Netherlands)

Van Rijn, Sophie; Aleman, Andre; De Sonneville, Leo; Swaab, Hanna

Because of the risk for development of psychopathology such as psychotic symptoms, it has been suggested that studying men with the XXY karyotype may help in the search for underlying cognitive, neural and genetic mechanisms. The aim of this study was to identify cognitive mechanisms that may

First-principles investigation of mechanical and electronic properties of tetragonal NbAl3 under tension

Science.gov (United States)

Jiao, Zhen; Liu, Qi-Jun; Liu, Fu-Sheng; Tang, Bin

2018-06-01

Using the density functional theory calculations, the mechanical and electronic properties of NbAl3 under different tensile loads were investigated. The calculated lattice parameters, elastic constants and mechanical properties (bulk modulus, shear modulus, Young's modulus, Poisson's ratio, Pugh's criterion and Cauchy's pressure) indicated that our results were in agreement with the published experimental and theoretical data at zero tension. With respect to NbAl3 under tension in this paper, the crystal structure was changed from tetragonal to orthorhombic under tension along the [100] and [101] directions. The NbAl3 crystal has been classified as brittle material under tension from 0 to 20 GPa. The obtained Young's modulus and Debye temperature monotonically decreased with increasing tension stress. Combining with mechanical and electronic properties in detail, the decreased mechanical properties were mainly due to the weakening of covalency.

Kinetic theory approach to modeling of cellular repair mechanisms under genome stress.

Directory of Open Access Journals (Sweden)

Jinpeng Qi

Full Text Available Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR by using mathematical framework of kinetic theory of active particles (KTAP. Firstly, we focus on illustrating the profile of Cellular Repair System (CRS instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs and Repair Protein (RP generating, DSB-protein complexes (DSBCs synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances.

Kinetic theory approach to modeling of cellular repair mechanisms under genome stress.

Science.gov (United States)

Qi, Jinpeng; Ding, Yongsheng; Zhu, Ying; Wu, Yizhi

2011-01-01

Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR) by using mathematical framework of kinetic theory of active particles (KTAP). Firstly, we focus on illustrating the profile of Cellular Repair System (CRS) instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances.

Control of a perturbed under-actuated mechanical system

KAUST Repository

Zayane, Chadia

2015-11-05

In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed high order sliding mode control architecture including a controller and differentiator allows to track accurately the predefined trajectory and to stabilize the internal dynamics. The robustness of the proposed approach is illustrated through different perturbation and output noise configurations.

Mechanisms underlying astringency: introduction to an oral tribology approach

Science.gov (United States)

Upadhyay, Rutuja; Brossard, Natalia; Chen, Jianshe

2016-03-01

Astringency is one of the predominant factors in the sensory experience of many foods and beverages ranging from wine to nuts. The scientific community is discussing mechanisms that explain this complex phenomenon, since there are no conclusive results which correlate well with sensory astringency. Therefore, the mechanisms and perceptual characteristics of astringency warrant further discussion and investigation. This paper gives a brief introduction of the fundamentals of oral tribology forming a basis of the astringency mechanism. It discusses the current state of the literature on mechanisms underlying astringency describing the existing astringency models. The review discusses the crucial role of saliva and its physiology which contributes significantly in astringency perception in the mouth. It also provides an overview of research concerned with the physiological and psychophysical factors that mediate the perception of this sensation, establishing the ground for future research. Thus, the overall aim of the review is to establish the critical roles of oral friction (thin-film lubrication) in the sensation of astringency and possibly of some other specific sensory features.

Study on Mechanical Properties of Barite Concrete under Impact Load

Science.gov (United States)

Chen, Z. F.; Cheng, K.; Wu, D.; Gan, Y. C.; Tao, Q. W.

2018-03-01

In order to research the mechanical properties of Barite concrete under impact load, a group of concrete compression tests was carried out under the impact load by using the drop test machine. A high-speed camera was used to record the failure process of the specimen during the impact process. The test results show that:with the increase of drop height, the loading rate, the peak load, the strain under peak load, the strain rate and the dynamic increase factor (DIF) all increase gradually. The ultimate tensile strain is close to each other, and the time of impact force decreases significantly, showing significant strain rate effect.

micro-mechanical experimental investigation and modelling of strain and damage of argillaceous rocks under combined hydric and mechanical loads

International Nuclear Information System (INIS)

Wang, L.

2012-01-01

The hydro-mechanical behavior of argillaceous rocks, which are possible host rocks for underground radioactive nuclear waste storage, is investigated by means of micro-mechanical experimental investigations and modellings. Strain fields at the micrometric scale of the composite structure of this rock, are measured by the combination of environmental scanning electron microscopy, in situ testing and digital image correlation technique. The evolution of argillaceous rocks under pure hydric loading is first investigated. The strain field is strongly heterogeneous and manifests anisotropy. The observed nonlinear deformation at high relative humidity (RH) is related not only to damage, but also to the nonlinear swelling of the clay mineral itself, controlled by different local mechanisms depending on RH. Irreversible deformations are observed during hydric cycles, as well as a network of microcracks located in the bulk of the clay matrix and/or at the inclusion-matrix interface. Second, the local deformation field of the material under combined hydric and mechanical loadings is quantified. Three types of deformation bands are evidenced under mechanical loading, either normal to stress direction (compaction), parallel (microcracking) or inclined (shear). Moreover, they are strongly controlled by the water content of the material: shear bands are in particular prone to appear at high RH states. In view of understanding the mechanical interactions a local scale, the material is modeled as a composite made of non-swelling elastic inclusions embedded in an elastic swelling clay matrix. The internal stress field induced by swelling strain incompatibilities between inclusions and matrix, as well as the overall deformation, is numerically computed at equilibrium but also during the transient stage associated with a moisture gradient. An analytical micro-mechanical model based on Eshelby's solution is proposed. In addition, 2D finite element computations are performed. Results

Progressive damage analysis of carbon/epoxy laminates under couple laser and mechanical loading

Directory of Open Access Journals (Sweden)

Wanlei Liu

Full Text Available A multiscale model based bridge theory is proposed for the progressive damage analysis of carbon/epoxy laminates under couple laser and mechanical loading. The ablation model is adopted to calculate ablation temperature changing and ablation surface degradation. The polynomial strengthening model of matrix is used to improve bridging model for reducing parameter input. Stiffness degradation methods of bridging model are also improved in order to analyze the stress redistribution more accurately when the damage occurs. Thermal-mechanical analyses of the composite plate are performed using the ABAQUS/Explicit program with the developed model implemented in the VUMAT. The simulation results show that this model can be used to proclaim the mesoscale damage mechanism of composite laminates under coupled loading. Keywords: Laser irradiation, Multiscale analysis, Bridge model, Thermal-mechanical

An NMDA Receptor-Dependent Mechanism Underlies Inhibitory Synapse Development

Directory of Open Access Journals (Sweden)

Xinglong Gu

2016-01-01

Full Text Available In the mammalian brain, GABAergic synaptic transmission provides inhibitory balance to glutamatergic excitatory drive and controls neuronal output. The molecular mechanisms underlying the development of GABAergic synapses remain largely unclear. Here, we report that NMDA-type ionotropic glutamate receptors (NMDARs in individual immature neurons are the upstream signaling molecules essential for GABAergic synapse development, which requires signaling via Calmodulin binding motif in the C0 domain of the NMDAR GluN1 subunit. Interestingly, in neurons lacking NMDARs, whereas GABAergic synaptic transmission is strongly reduced, the tonic inhibition mediated by extrasynaptic GABAA receptors is increased, suggesting a compensatory mechanism for the lack of synaptic inhibition. These results demonstrate a crucial role for NMDARs in specifying the development of inhibitory synapses, and suggest an important mechanism for controlling the establishment of the balance between synaptic excitation and inhibition in the developing brain.

Damage evolution of TBC system under in-phase thermo-mechanical tests

International Nuclear Information System (INIS)

Kitazawa, R.; Tanaka, M.; Kagawa, Y.; Liu, Y.F.

2010-01-01

In-phase thermo-mechanical tests (TMF) of EB-PVD Y 2 O 3 -ZrO 2 thermal barrier coating (TBC) system (8 wt% Y 2 O 3 -ZrO 2 /CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

Mechanical properties of graphene nanoribbons under uniaxial tensile strain

Science.gov (United States)

Yoneyama, Kazufumi; Yamanaka, Ayaka; Okada, Susumu

2018-03-01

Based on the density functional theory with the generalized gradient approximation, we investigated the mechanical properties of graphene nanoribbons in terms of their edge shape under a uniaxial tensile strain. The nanoribbons with armchair and zigzag edges retain their structure under a large tensile strain, while the nanoribbons with chiral edges are fragile against the tensile strain compared with those with armchair and zigzag edges. The fracture started at the cove region, which corresponds to the border between the zigzag and armchair edges for the nanoribbons with chiral edges. For the nanoribbons with armchair edges, the fracture started at one of the cove regions at the edges. In contrast, the fracture started at the inner region of the nanoribbons with zigzag edges. The bond elongation under the tensile strain depends on the mutual arrangement of covalent bonds with respect to the strain direction.

Incidence, aetiology and prevention of musculoskeletal injuries in volleyball: A systematic review of the literature.

Science.gov (United States)

Kilic, O; Maas, M; Verhagen, E; Zwerver, J; Gouttebarge, V

2017-07-01

Currently, there is no overview of the incidence and (volleyball-specific) risk factors of musculoskeletal injuries among volleyball players, nor any insight into the effect of preventive measures on the incidence of injuries in volleyball. This study aimed to review systematically the scientific evidence on the incidence, prevalence, aetiology and preventive measures of volleyball injuries. To this end, a highly sensitive search strategy was built based on two groups of keywords (and their synonyms). Two electronic databases were searched, namely Medline (biomedical literature) via Pubmed, and SPORTDiscus (sports and sports medicine literature) via EBSCOhost. The results showed that ankle, knee and shoulder injuries are the most common injuries sustained while playing volleyball. Results are presented separately for acute and overuse injuries, as well as for contact and non-contact injuries. Measures to prevent musculoskeletal injuries, anterior knee injuries and ankle injuries were identified in the scientific literature. These preventive measures were found to have a significant effect on decreasing the occurrence of volleyball injuries (for instance on ankle injuries with a reduction from 0.9 to 0.5 injuries per 1000 player hours). Our systematic review showed that musculoskeletal injuries are common among volleyball players, while effective preventive measures remain scarce. Further epidemiological studies should focus on other specific injuries besides knee and ankle injuries, and should also report their prevalence and not only the incidence. Additionally, high-quality studies on the aetiology and prevention of shoulder injuries are lacking and should be a focus of future studies.

Mechanical Design of AM Fabricated Prismatic Rods under Torsion

Directory of Open Access Journals (Sweden)

Manzhirov Alexander V.

2017-01-01

Full Text Available We study the stress-strain state of viscoelastic prismatic rods fabricated or repaired by additive manufacturing technologies under torsion. An adequate description of the processes involved is given by methods of a new scientific field, mechanics of growing solids. Three main stages of the deformation process (before the beginning of growth, in the course of growth, and after the termination of growth are studied. Two versions of statement of two problems are given: (i given the torque, find the stresses, displacements, and torsion; (ii given the torsion, find the stresses, displacements, and torque. Solution methods using techniques of complex analysis are presented. The results can be used in mechanical and instrument engineering.

Mechanical and tribological behaviour of molten salt processed self-lubricated aluminium composite under different treatments

Science.gov (United States)

Kannan, C.; Ramanujam, R.

2018-05-01

The aim of this research work is to evaluate the mechanical and tribological behaviour of Al 7075 based self-lubricated hybrid nanocomposite under different treated conditions viz. as-cast, T6 and deep cryo treated. In order to overcome the drawbacks associated with conventional stir casting, a combinational approach that consists of molten salt processing, ultrasonic assistance and optimized mechanical stirring is adopted in this study to fabricate the nanocomposite. The mechanical characterisation tests carried out on this nanocomposite reveals an improvement of about 39% in hardness and 22% in ultimate tensile strength possible under T6 condition. Under specific conditions, the wear rate can be reduced to the extent of about 63% through the usage of self-lubricated hybrid nanocomposite under T6 condition.

Molecular mechanics of silk nanostructures under varied mechanical loading.

Science.gov (United States)

Bratzel, Graham; Buehler, Markus J

2012-06-01

Spider dragline silk is a self-assembling tunable protein composite fiber that rivals many engineering fibers in tensile strength, extensibility, and toughness, making it one of the most versatile biocompatible materials and most inviting for synthetic mimicry. While experimental studies have shown that the peptide sequence and molecular structure of silk have a direct influence on the stiffness, toughness, and failure strength of silk, few molecular-level analyses of the nanostructure of silk assemblies, in particular, under variations of genetic sequences have been reported. In this study, atomistic-level structures of wildtype as well as modified MaSp1 protein from the Nephila clavipes spider dragline silk sequences, obtained using an in silico approach based on replica exchange molecular dynamics and explicit water molecular dynamics, are subjected to simulated nanomechanical testing using different force-control loading conditions including stretch, pull-out, and peel. The authors have explored the effects of the poly-alanine length of the N. clavipes MaSp1 peptide sequence and identify differences in nanomechanical loading conditions on the behavior of a unit cell of 15 strands with 840-990 total residues used to represent a cross-linking β-sheet crystal node in the network within a fibril of the dragline silk thread. The specific loading condition used, representing concepts derived from the protein network connectivity at larger scales, have a significant effect on the mechanical behavior. Our analysis incorporates stretching, pull-out, and peel testing to connect biochemical features to mechanical behavior. The method used in this study could find broad applications in de novo design of silk-like tunable materials for an array of applications. Copyright © 2011 Wiley Periodicals, Inc.

Temporomandibular disorders and painful comorbidities: clinical association and underlying mechanisms.

Science.gov (United States)

Costa, Yuri Martins; Conti, Paulo César Rodrigues; de Faria, Flavio Augusto Cardoso; Bonjardim, Leonardo Rigoldi

2017-03-01

The association between temporomandibular disorders (TMDs) and headaches, cervical spine dysfunction, and fibromyalgia is not artefactual. The aim of this review is to describe the comorbid relationship between TMD and these three major painful conditions and to discuss the clinical implications and the underlying pain mechanisms involved in these relationships. Common neuronal pathways and central sensitization processes are acknowledged as the main factors for the association between TMD and primary headaches, although the establishment of cause-effect mechanisms requires further clarification and characterization. The biomechanical aspects are not the main factors involved in the comorbid relationship between TMD and cervical spine dysfunction, which can be better explained by the neuronal convergence of the trigeminal and cervical spine sensory pathways as well as by central sensitization processes. The association between TMD and fibromyalgia also has supporting evidence in the literature, and the proposed main mechanism underlying this relationship is the impairment of the descending pain inhibitory system. In this particular scenario, a cause-effect relationship is more likely to occur in one direction, that is, fibromyalgia as a risk factor for TMD. Therefore, clinical awareness of the association between TMD and painful comorbidities and the support of multidisciplinary approaches are required to recognize these related conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

Carbon Footprint Management of Road Freight Transport under the Carbon Emission Trading Mechanism

Directory of Open Access Journals (Sweden)

Jin Li

2015-01-01

Full Text Available Growing concern over environmental issues has considerably increased the number of regulations and legislation that aim to curb carbon emissions. Carbon emission trading mechanism, which is one of the most effective means, has been broadly adopted by several countries. This paper presents a road truck routing problem under the carbon emission trading mechanism. By introducing a calculation method of carbon emissions that considers the load and speed of the vehicle among other factors, a road truck routing optimizing model under the cap and trade mechanism based on the Travelling Salesman Problem (TSP is described. Compared with the classical TSP model that only considers the economic cost, this model suggests that the truck routing decision under the cap and trade mechanism is more effective in reducing carbon emissions. A modified tabu search algorithm is also proposed to obtain solutions within a reasonable amount of computation time. We theoretically and numerically examine the impacts of carbon trading, carbon cap, and carbon price on truck routing decision, carbon emissions, and total cost. From the results of numerical experiments, we derive interesting observations about how to control the total cost and reduce carbon emissions.

Two distinct neural mechanisms underlying indirect reciprocity.

Science.gov (United States)

Watanabe, Takamitsu; Takezawa, Masanori; Nakawake, Yo; Kunimatsu, Akira; Yamasue, Hidenori; Nakamura, Mitsuhiro; Miyashita, Yasushi; Masuda, Naoki

2014-03-18

Cooperation is a hallmark of human society. Humans often cooperate with strangers even if they will not meet each other again. This so-called indirect reciprocity enables large-scale cooperation among nonkin and can occur based on a reputation mechanism or as a succession of pay-it-forward behavior. Here, we provide the functional and anatomical neural evidence for two distinct mechanisms governing the two types of indirect reciprocity. Cooperation occurring as reputation-based reciprocity specifically recruited the precuneus, a region associated with self-centered cognition. During such cooperative behavior, the precuneus was functionally connected with the caudate, a region linking rewards to behavior. Furthermore, the precuneus of a cooperative subject had a strong resting-state functional connectivity (rsFC) with the caudate and a large gray matter volume. In contrast, pay-it-forward reciprocity recruited the anterior insula (AI), a brain region associated with affective empathy. The AI was functionally connected with the caudate during cooperation occurring as pay-it-forward reciprocity, and its gray matter volume and rsFC with the caudate predicted the tendency of such cooperation. The revealed difference is consistent with the existing results of evolutionary game theory: although reputation-based indirect reciprocity robustly evolves as a self-interested behavior in theory, pay-it-forward indirect reciprocity does not on its own. The present study provides neural mechanisms underlying indirect reciprocity and suggests that pay-it-forward reciprocity may not occur as myopic profit maximization but elicit emotional rewards.

Cavitation behavior observed in three monoleaflet mechanical heart valves under accelerated testing conditions.

Science.gov (United States)

Lo, Chi-Wen; Liu, Jia-Shing; Li, Chi-Pei; Lu, Po-Chien; Hwang, Ned H

2008-01-01

Accelerated testing provides a substantial amount of data on mechanical heart valve durability in a short period of time, but such conditions may not accurately reflect in vivo performance. Cavitation, which occurs during mechanical heart valve closure when local flow field pressure decreases below vapor pressure, is thought to play a role in valve damage under accelerated conditions. The underlying flow dynamics and mechanisms behind cavitation bubble formation are poorly understood. Under physiologic conditions, random perivalvular cavitation is difficult to capture. We applied accelerated testing at a pulse rate of 600 bpm and transvalvular pressure of 120 mm Hg, with synchronized videographs and high-frequency pressure measurements, to study cavitation of the Medtronic Hall Standard (MHS), Medtronic Hall D-16 (MHD), and Omni Carbon (OC) valves. Results showed cavitation bubbles between 340 and 360 micros after leaflet/housing impact of the MHS, MHD, and OC valves, intensified by significant leaflet rebound. Squeeze flow, Venturi, and water hammer effects each contributed to cavitation, depending on valve design.

Mechanisms underlying KCNQ1channel cell volume sensitivity

DEFF Research Database (Denmark)

Hammami, Sofia

Cells are constantly exposed to changes in cell volume during cell metabolism, nutrient uptake, cell proliferation, cell migration and salt and water transport. In order to cope with these perturbations, potassium channels in line with chloride channels have been shown to be likely contributors...... to the process of cell volume adjustments. A great diversity of potassium channels being members of either the 6TM, 4 TM or 2 TM K+ channel gene family have been shown to be strictly regulated by small, fast changes in cell volume. However, the precise mechanism underlying the K+ channel sensitivity to cell...... volume alterations is not yet fully understood. The KCNQ1 channel belonging to the voltage gated KCNQ family is considered a precise sensor of volume changes. The goal of this thesis was to elucidate the mechanism that induces cell volume sensitivity. Until now, a number of investigators have implicitly...

Quantification and localisation of damage in rat muscles after controlled loading; a new approach to study the aetiology of pressure sores

NARCIS (Netherlands)

Bosboom, E.M.H.; Bouten, C.V.C.; Oomens, C.W.J.; Straaten, van H.W.M.; Baaijens, F.P.T.; Kuipers, H.

2001-01-01

To obtain more insight in the aetiology of deep pressure sores, an animal model was developed to relate controlled externalloading to local muscle damage. The tibialis anterior muscle (TA) and overlying skin of a rat were compressed between indentorand tibia. Loads of 10, 70 and 250 kPa at skin

Crack formation and crack propagation under multiaxial mechanical and thermal stresses. Proceedings

International Nuclear Information System (INIS)

1993-01-01

The 25th meeting of the DV Fracture Group was held on 16/17 February 1993 at Karlsruhe Technical University. The main topic, ''Crack formation and crack propagation under multiaxial mechanical and thermal stresses'', was discussed by five invited papers (by K.J. Miller, D. Loehe, H.A. Richard, W. Brocks, A. Brueckner-Foit) and 23 short papers. The other 21 papers were devoted to various domains of fracture mechanics, with emphasis on elastoplastic fracture mechanics. (orig./MM) [de

A mechanical deformation model of metallic fuel pin under steady state conditions

International Nuclear Information System (INIS)

Lee, D. W.; Lee, B. W.; Kim, Y. I.; Han, D. H.

2004-01-01

As a mechanical deformation model of the MACSIS code predicts the cladding deformation due to the simple thin shell theory, it is impossible to predict the FCMI(Fuel-Cladding Mechanical Interaction). Therefore, a mechanical deformation model used the generalized plane strain is developed. The DEFORM is a mechanical deformation routine which is used to analyze the stresses and strains in the fuel and cladding of a metallic fuel pin of LMRs. The accuracy of the program is demonstrated by comparison of the DEFORM predictions with the result of another code calculations or experimental results in literature. The stress/strain distributions of elastic part under free thermal expansion condition are completely matched with the results of ANSYS code. The swelling and creep solutions are reasonably well agreed with the simulations of ALFUS and LIFE-M codes, respectively. The predicted cladding strains are under estimated than experimental data at the range of high burnup. Therefore, it is recommended that the fine tuning of the DEFORM based on various range of experimental data

Damage evolution of TBC system under in-phase thermo-mechanical tests

Energy Technology Data Exchange (ETDEWEB)

Kitazawa, R.; Tanaka, M.; Kagawa, Y. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Liu, Y.F., E-mail: yfliu@hyper.rcast.u-tokyo.ac.jp [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan)

2010-10-15

In-phase thermo-mechanical tests (TMF) of EB-PVD Y{sub 2}O{sub 3}-ZrO{sub 2} thermal barrier coating (TBC) system (8 wt% Y{sub 2}O{sub 3}-ZrO{sub 2}/CoNiCrAlY/IN-738 substrate) were done under a through-the-thick-direction thermal gradient from TBC surface temperature at 1150 deg. C to substrate temperature at 1000 deg. C. Deformation and failure behaviors of the TBC system were observed at the macroscopic and microscopic scales and damage evolution of the system under in-phase thermo-mechanical test was discussed. Special attention was paid to TBC layer cracking, thermally grown oxide (TGO) layer formation and void formation in bond coat and substrate. Effect of TMF conditions on the damage evolution behaviors was also discussed.

Underlying mechanism in the water chemistry of nuclear systems

International Nuclear Information System (INIS)

Walton, G.N.

1978-01-01

The equilibrium between dissolved hydrogen and oxygen in the molecular decomposition of water, and the equilibrium between hydrogen ions and hydroxyl ions in the ionic dissociation of water, both constitute important underlying mechanisms in the corrosion behaviour of water. The two equilibria, and the rates of the reactions involved in water and steam, will be compared and contrasted as a function of temperature, pressure and radiation. The effects of the equilibria on the hydrolysis and solubility of ferrous and ferric ions, and the ions of other metals, will be discussed in relation to the control of conditions in the coolant circuits of nuclear reactors. A third mechanism to discussed is the electrochemical exchange reactions that can contribute to the contamination of circuits. (author)

Occurrence, aetiology and challenges in the management of congestive heart failure in sub-saharan Africa: experience of the Cardiac Centre in Shisong, Cameroon

Directory of Open Access Journals (Sweden)

Tantchou Tchoumi Jacques Cabral

2011-02-01

Full Text Available INTRODUCTION: The aim of the study was to investigate the occurrence, the aetiology and the management of congestive heart failure in the cardiac centre of the St. Elizabeth catholic general hospital Shisong in Cameroon. METHODS: Between November 2002 and November 2008, a population of 8121 patients was consulted in the referral cardiac centre of St. Elizabeth Catholic General Hospital. Of these patients, 462 were diagnosed with congestive heart failure according to the modified Framingham criteria for the diagnosis of heart failure. Complementary investigations used to confirm and establish the aetiology of the disease were the chest X-ray, electrocardiography, bi-dimensional Doppler echocardiography. RESULTS: The results showed that the occurrence of congestive heart failure in our centre was 5,7%. Congestive heart failure was diagnosed in 198 females and 264 males, aged between 8 and 86 years old (42.5, plus or minus 18 years old. Post rheumatic valvulopathies (14.6% and congenital heart diseases (1.9% were the first aetiologic factor of congestive heart failure in the young, meanwhile cardiomyopathies (8,3% in elderly followed by hypertensive cardiomyopathy (4.4%. Congestive heart failure was also seen in adults with congenital heart diseases in 0.01%. In this zone of Cameroon, we discovered that HIV cardiomyopathy (1.6% and Cor pulmonale (8% were represented, aetiological factors not mentioned in previous studies conducted in urban areas of Cameroon. The mean duration of hospital stay for the compensation treatment was thirteen days, ranging between 7 and 21 days, the mortality being 9.2%. All the medications recommended for the treatment of congestive heart failure are available in our centre but many patients are not compliant to the therapy or cannot afford them. Financial limitation is causing the exacerbation of the disease and premature death. CONCLUSION: Our data show a high incidence of congestive heart failure mainly due to post

An Activating Mechanism of Aggressive Behaviour in Disorganised Attachment: A Moment-to-Moment Case Analysis of a Three-Year-Old

Science.gov (United States)

Kim, Eun Young

2010-01-01

This study examines an activating mechanism of aggressive behaviour in young children. Many studies on attachment theories have indicated disorganised attachment as a significant risk factor for externalising problems and have explained the aetiology of disorganised attachment in terms of deficits in affect, behaviour and cognitive functions from…

Neuroprotective Mechanisms Activated in Non-seizing Rats Exposed to Sarin

Science.gov (United States)

2015-06-04

after kainic acid-induced seizures. Brain Res. 1424, 1–8. Johnson, E.A., Kan, R.K., 2010. The acute phase response and soman-induced status epilepticus ...2011. Comparison of status epilepticus models induced by pilocarpine and nerve agents – a systematic review of the underlying aetiology and adopted...2007) Nqo2 Loss of Nqo1 and Nqo2 leads to altered intracellular redox status , decreased expression and activation of NF-κB, and altered

Music and Memory in Alzheimer's Disease and The Potential Underlying Mechanisms.

Science.gov (United States)

Peck, Katlyn J; Girard, Todd A; Russo, Frank A; Fiocco, Alexandra J

2016-01-01

With population aging and a projected exponential expansion of persons diagnosed with Alzheimer's disease (AD), the development of treatment and prevention programs has become a fervent area of research and discovery. A growing body of evidence suggests that music exposure can enhance memory and emotional function in persons with AD. However, there is a paucity of research that aims to identify specific underlying neural mechanisms associated with music's beneficial effects in this particular population. As such, this paper reviews existing anecdotal and empirical evidence related to the enhancing effects of music exposure on cognitive function and further provides a discussion on the potential underlying mechanisms that may explain music's beneficial effect. Specifically, this paper will outline the potential role of the dopaminergic system, the autonomic nervous system, and the default network in explaining how music may enhance memory function in persons with AD.

Plant-insect interactions under bacterial influence: ecological implications and underlying mechanisms.

Science.gov (United States)

Sugio, Akiko; Dubreuil, Géraldine; Giron, David; Simon, Jean-Christophe

2015-02-01

Plants and insects have been co-existing for more than 400 million years, leading to intimate and complex relationships. Throughout their own evolutionary history, plants and insects have also established intricate and very diverse relationships with microbial associates. Studies in recent years have revealed plant- or insect-associated microbes to be instrumental in plant-insect interactions, with important implications for plant defences and plant utilization by insects. Microbial communities associated with plants are rich in diversity, and their structure greatly differs between below- and above-ground levels. Microbial communities associated with insect herbivores generally present a lower diversity and can reside in different body parts of their hosts including bacteriocytes, haemolymph, gut, and salivary glands. Acquisition of microbial communities by vertical or horizontal transmission and possible genetic exchanges through lateral transfer could strongly impact on the host insect or plant fitness by conferring adaptations to new habitats. Recent developments in sequencing technologies and molecular tools have dramatically enhanced opportunities to characterize the microbial diversity associated with plants and insects and have unveiled some of the mechanisms by which symbionts modulate plant-insect interactions. Here, we focus on the diversity and ecological consequences of bacterial communities associated with plants and herbivorous insects. We also highlight the known mechanisms by which these microbes interfere with plant-insect interactions. Revealing such mechanisms in model systems under controlled environments but also in more natural ecological settings will help us to understand the evolution of complex multitrophic interactions in which plants, herbivorous insects, and micro-organisms are inserted. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions

Chronic fatigue syndrome: aetiology, diagnosis and treatment

Science.gov (United States)

Avellaneda Fernández, Alfredo; Pérez Martín, Álvaro; Izquierdo Martínez, Maravillas; Arruti Bustillo, Mar; Barbado Hernández, Francisco Javier; de la Cruz Labrado, Javier; Díaz-Delgado Peñas, Rafael; Gutiérrez Rivas, Eduardo; Palacín Delgado, Cecilia; Rivera Redondo, Javier; Ramón Giménez, José Ramón

2009-01-01

Chronic fatigue syndrome is characterised by intense fatigue, with duration of over six months and associated to other related symptoms. The latter include asthenia and easily induced tiredness that is not recovered after a night's sleep. The fatigue becomes so severe that it forces a 50% reduction in daily activities. Given its unknown aetiology, different hypotheses have been considered to explain the origin of the condition (from immunological disorders to the presence of post-traumatic oxidative stress), although there are no conclusive diagnostic tests. Diagnosis is established through the exclusion of other diseases causing fatigue. This syndrome is rare in childhood and adolescence, although the fatigue symptom per se is quite common in paediatric patients. Currently, no curative treatment exists for patients with chronic fatigue syndrome. The therapeutic approach to this syndrome requires a combination of different therapeutic modalities. The specific characteristics of the symptomatology of patients with chronic fatigue require a rapid adaptation of the educational, healthcare and social systems to prevent the problems derived from current systems. Such patients require multidisciplinary management due to the multiple and different issues affecting them. This document was realized by one of the Interdisciplinary Work Groups from the Institute for Rare Diseases, and its aim is to point out the main social and care needs for people affected with Chronic Fatigue Syndrome. For this, it includes not only the view of representatives for different scientific societies, but also the patient associations view, because they know the true history of their social and sanitary needs. In an interdisciplinary approach, this work also reviews the principal scientific, medical, socio-sanitary and psychological aspects of Chronic Fatigue Syndrome. PMID:19857242

Insights into the Mechanisms Underlying Boron Homeostasis in Plants

Directory of Open Access Journals (Sweden)

Akira Yoshinari

2017-11-01

Full Text Available Boron is an essential element for plants but is toxic in excess. Therefore, plants must adapt to both limiting and excess boron conditions for normal growth. Boron transport in plants is primarily based on three transport mechanisms across the plasma membrane: passive diffusion of boric acid, facilitated diffusion of boric acid via channels, and export of borate anion via transporters. Under boron -limiting conditions, boric acid channels and borate exporters function in the uptake and translocation of boron to support growth of various plant species. In Arabidopsis thaliana, NIP5;1 and BOR1 are located in the plasma membrane and polarized toward soil and stele, respectively, in various root cells, for efficient transport of boron from the soil to the stele. Importantly, sufficient levels of boron induce downregulation of NIP5;1 and BOR1 through mRNA degradation and proteolysis through endocytosis, respectively. In addition, borate exporters, such as Arabidopsis BOR4 and barley Bot1, function in boron exclusion from tissues and cells under conditions of excess boron. Thus, plants actively regulate intracellular localization and abundance of transport proteins to maintain boron homeostasis. In this review, the physiological roles and regulatory mechanisms of intracellular localization and abundance of boron transport proteins are discussed.

PHYSIOLOGICAL QUALITY OF SOYBEAN SEEDS UNDER MECHANICAL INJURIES CAUSED BY COMBINES

OpenAIRE

FÁBIO PALCZEWSKI PACHECO; LÚCIA HELENA PEREIRA NÓBREGA; GISLAINE PICOLLO DE LIMA; MÁRCIA SANTORUM; WALTER BOLLER; LORIVAN FORMIGHIERI

2015-01-01

The mechanical harvesting causes injuries on seeds and may affect their quality. Different threshing mechanisms and their adjustments may also affect the intensity of impacts that machines cause on seeds. So, this study aimed at diagnosing and evaluating the effect of two combines: the first one with a threshing system of axial flow and the other one with a threshing system of tangential flow, under adjustments of concave opening (10 mm, 30 mm and 10 mm for a combine with axial ...

Frictional behaviour of polymer films under mechanical and electrostatic loads

International Nuclear Information System (INIS)

Ginés, R; Christen, R; Motavalli, M; Bergamini, A; Ermanni, P

2013-01-01

Different polymer foils, namely polyimide, FEP, PFA and PVDF were tested on a setup designed to measure the static coefficient of friction between them. The setup was designed according to the requirements of a damping device based on electrostatically tunable friction. The foils were tested under different mechanically applied forces and showed reproducible results for the static coefficient of friction. With the same setup the measurements were performed under an electric field as the source of the normal force. Up to a certain electric field the values were in good agreement. Beyond this field discrepancies were found. (paper)

Failure mechanism of monolayer graphene under hypervelocity impact of spherical projectile

Science.gov (United States)

Xia, Kang; Zhan, Haifei; Hu, De'An; Gu, Yuantong

2016-09-01

The excellent mechanical properties of graphene have enabled it as appealing candidate in the field of impact protection or protective shield. By considering a monolayer graphene membrane, in this work, we assessed its deformation mechanisms under hypervelocity impact (from 2 to 6 km/s), based on a serial of in silico studies. It is found that the cracks are formed preferentially in the zigzag directions which are consistent with that observed from tensile deformation. Specifically, the boundary condition is found to exert an obvious influence on the stress distribution and transmission during the impact process, which eventually influences the penetration energy and crack growth. For similar sample size, the circular shape graphene possesses the best impact resistance, followed by hexagonal graphene membrane. Moreover, it is found the failure shape of graphene membrane has a strong relationship with the initial kinetic energy of the projectile. The higher kinetic energy, the more number the cracks. This study provides a fundamental understanding of the deformation mechanisms of monolayer graphene under impact, which is crucial in order to facilitate their emerging future applications for impact protection, such as protective shield from orbital debris for spacecraft.

Behavior of duplex stainless steel casting defects under mechanical loadings

Energy Technology Data Exchange (ETDEWEB)

Jayet-Gendrot, S [Electricite de France, 77 - Moret-sur-Loing (France). Dept. of Materials Study; Gilles, P; Migne, C [Societe Franco-Americaine de Constructions Atomiques (FRAMATOME), 92 - Paris-La-Defense (France)

1997-04-01

Several components in the primary circuit of pressurized water reactors are made of cast duplex stainless steels. This material contains small casting defects, mainly shrinkage cavities, due to the manufacturing process. In safety analyses, the structural integrity of the components is studied. In order to assess the real severity of the casting defects under mechanical loadings, an experimental program was carried out. It consisted of testing, under both cyclic and monotonic solicitations, three-point bend specimens containing either a natural defect (in the form of a localized cluster of cavities) or a machined notch having the dimensions of the cluster`s envelope. The tests are analyzed in order to develop a method that takes into account the behavior of castings defects in a more realistic fashion than by an envelope crack. Various approaches are investigated, including the search of equivalent defects or of criteria based on continuum mechanics concepts, and compared with literature data. This study shows the conservatism of current safety analyses in modelling casting defects by envelope semi-elliptical cracks and contributes to the development of alternative approaches. (author) 18 refs.

Shared genetic aetiology of puberty timing between sexes and with health-related outcomes.

Science.gov (United States)

Day, Felix R; Bulik-Sullivan, Brendan; Hinds, David A; Finucane, Hilary K; Murabito, Joanne M; Tung, Joyce Y; Ong, Ken K; Perry, John R B

2015-11-09

Understanding of the genetic regulation of puberty timing has come largely from studies of rare disorders and population-based studies in women. Here, we report the largest genomic analysis for puberty timing in 55,871 men, based on recalled age at voice breaking. Analysis across all genomic variants reveals strong genetic correlation (0.74, P=2.7 × 10(-70)) between male and female puberty timing. However, some loci show sex-divergent effects, including directionally opposite effects between sexes at the SIM1/MCHR2 locus (Pheterogeneity=1.6 × 10(-12)). We find five novel loci for puberty timing (Ppuberty, LEPR and KAL1. Finally, we identify genetic correlations that indicate shared aetiologies in both sexes between puberty timing and body mass index, fasting insulin levels, lipid levels, type 2 diabetes and cardiovascular disease.

Nonlinear Mechanics of MEMS Rectangular Microplates under Electrostatic Actuation

KAUST Repository

Saghir, Shahid

2016-12-01

The first objective of the dissertation is to develop a suitable reduced order model capable of investigating the nonlinear mechanical behavior of von-Karman plates under electrostatic actuation. The second objective is to investigate the nonlinear static and dynamic behavior of rectangular microplates under small and large actuating forces. In the first part, we present and compare various approaches to develop reduced order models for the nonlinear von-Karman rectangular microplates actuated by nonlinear electrostatic forces. The reduced-order models aim to investigate the static and dynamic behavior of the plate under small and large actuation forces. A fully clamped microplate is considered. Different types of basis functions are used in conjunction with the Galerkin method to discretize the governing equations. First we investigate the convergence with the number of modes retained in the model. Then for validation purpose, a comparison of the static results is made with the results calculated by a nonlinear finite element model. The linear eigenvalue problem for the plate under the electrostatic force is solved for a wide range of voltages up to pull-in. In the second part, we present an investigation of the static and dynamic behavior of a fully clamped microplate. We investigate the effect of different non-dimensional design parameters on the static response. The forced-vibration response of the plate is then investigated when the plate is excited by a harmonic AC load superimposed to a DC load. The dynamic behavior is examined near the primary and secondary (superharmonic and subharmonic) resonances. The microplate shows a strong hardening behavior due to the cubic nonlinearity of midplane stretching. However, the behavior switches to softening as the DC load is increased. Next, near-square plates are studied to understand the effect of geometric imperfections of microplates. In the final part of the dissertation, we investigate the mechanical behavior of

Neural mechanisms underlying morphine withdrawal in addicted patients: a review

Directory of Open Access Journals (Sweden)

Nima Babhadiashar

2015-06-01

Full Text Available Morphine is one of the most potent alkaloid in opium, which has substantial medical uses and needs and it is the first active principle purified from herbal source. Morphine has commonly been used for relief of moderate to severe pain as it acts directly on the central nervous system; nonetheless, its chronic abuse increases tolerance and physical dependence, which is commonly known as opiate addiction. Morphine withdrawal syndrome is physiological and behavioral symptoms that stem from prolonged exposure to morphine. A majority of brain regions are hypofunctional over prolonged abstinence and acute morphine withdrawal. Furthermore, several neural mechanisms are likely to contribute to morphine withdrawal. The present review summarizes the literature pertaining to neural mechanisms underlying morphine withdrawal. Despite the fact that morphine withdrawal is a complex process, it is suggested that neural mechanisms play key roles in morphine withdrawal.

Lactate level, aetiology and mortality of adult patients in an emergency department

DEFF Research Database (Denmark)

Pedersen, Mathilde; Brandt, Vibeke Schnack; Holler, Jon Gitz

2015-01-01

BACKGROUND: Increased lactate is associated with high mortality among patients with suspected infection or trauma in the emergency department (ED), but the association with patients with other aetiologies is less well described. The aim of this study was to describe the relation between lactate......, lactate level showed to be useful in patients with infection (0.78, 95% CI 0.73 to 0.84), trauma (0.78, 95% CI 0.65 to 0.92), cardiac diseases (0.83, 95% CI 0.75 to 0.91) and gastrointestinal diseases (0.83, 95% CI 0.68 to 0.98). Lactate level was not useful in neurological (0.58, 95% CI 0.50 to 0.......67) and respiratory disease (0.64, 95% CI 0.55 to 0.74), and of uncertain value in the remaining diagnostic groups. CONCLUSIONS: Among adult ED patients, the prognostic value of lactate varies between diagnostic groups....

Investigating risk factors and possible infectious aetiologies of mummified fetuses on a large piggery in Australia.

Science.gov (United States)

Dron, N; Hernández-Jover, M; Doyle, R E; Holyoake, P K

2014-12-01

To investigate risk factors and potential infectious aetiologies of an increased mummification rate (>2%) identified over time on a 1200-sow farrow-to-finish farm in Australia. Association of potential non-infectious risk factors and the mummification rate was investigated using 15 years of breeding herd data (40,940 litters) and logistic regression analysis. Samples from a limited number of mummified fetuses were taken to identify potential infectious aetiologies (porcine parvovirus, Leptospira pomona, porcine circovirus type 2, Bungowannah virus and enterovirus). Logistic regression analysis suggested that the mummification rate was significantly associated with sow breed and parity, year and total born and stillborn piglets per litter. The mummification rate was lower (P < 0.001) in Landrace (3.4%) and Large White (2.6%) sows than in Duroc sows (4.9%). Gilts (2.9%) had a lower (P < 0.001) mummification rate than older sows. The mummification rate increased with total born litter size and decreased with the number of stillborn piglets (P < 0.001). A clustering effect within individual sows was identified, indicating that some sows with mummified fetuses in a litter were more likely to have repeated mummifications in subsequent litters. No infectious agents were identified in the samples taken. Results from this study suggest that the increased mummification rate identified over time on this farm is likely to be a non-infectious multifactorial problem predisposing the occurrence of mummification. Further research is required to better understand the pathophysiology of mummification and the role that different non-infectious factors play in the occurrence of mummified fetuses. © 2014 Australian Veterinary Association.

Establishing a birth cohort to investigate the course and aetiology of asthma and allergies across three generations - rationale, design, and methods of the ACROSSOLAR study.

Science.gov (United States)

Weinmann, Tobias; Gerlich, Jessica; Heinrich, Sabine; Nowak, Dennis; Gerdes, Jennifer; Schlichtiger, Jenny; von Mutius, Erika; Schaub, Bianca; Vogelberg, Christian; Roller, Diana; Radon, Katja

2015-12-04

Atopic diseases are a major burden of disease on a global scale. Regarding their aetiology, the early years of life are assumed to play a crucial role. In addition, there is growing evidence that elucidating the impact of cross-generational effects and epigenetic mechanisms such as DNA methylation can substantially widen the scientific knowledge of the occurrence and progression of these diseases. We are thus aiming at following the course of asthma, allergies, and potential risk factors for their occurrence across three generations by establishing a birth cohort in the offspring of an existing population-based cohort. 2051 young adults who have been recruited in 1995 for Phase II of the International Study of Asthma and Allergies in Childhood (ISAAC) and who have subsequently been followed-up by the Study on Occupational Allergy Risks (SOLAR) are asked bi-annually since 2009 if they conceived a child in the meantime. If parenthood is reported, parents are invited to enrol along with their children in the ACROSSOLAR cohort. Participation involves completing a questionnaire assessing general and health-related information about the course of the pregnancy and the first year of life of their children. Subsequently, the children are followed up until primary school age when asthma and allergies can be diagnosed reliably. In addition, DNA for epigenetic analysis will be collected and analysed. Longitudinal data analysis techniques will then be used to assess potential associations between early-life exposures and onset of childhood asthma and allergies taking into account epigenetics. Birth cohorts are especially suited to elucidate the impact of genetic predisposition, epigenetics, exposures during the first years of life, and gene-environment interactions on the occurrence and progression of asthma and allergies. By building upon an existing cohort, ACROSSOLAR offers a unique and cost-effective opportunity to investigate the aetiology of atopic disease in a

Unified Balance Scale: an activity-based, bed to community, and aetiology-independent measure of balance calibrated with Rasch analysis.

Science.gov (United States)

La Porta, Fabio; Franceschini, Marco; Caselli, Serena; Cavallini, Paola; Susassi, Sonia; Tennant, Alan

2011-04-01

To build a new activity-based, "bed to community", aetiology-independent measure of balance within the neurological rehabilitation setting by merging some existing scales. Balance scales were selected using a conceptual framework and subsequently administered to a convenience sample of adult patients with balance problems due to different neurological aetiologies. Data were then processed using classical psychometric analyses and Rasch analysis in order to construct a new balance measurement tool. The Berg Balance Scale, the Tinetti Scales and the Fullerton Advanced Balance Scale were selected and administered to a sample of patients, giving 302 observations. Classical psychometric analyses (item and scale analysis; confirmatory factor analysis) were undertaken on the pooled 40-item set with confirmation of unidimensionality. The subsequent Rasch analysis allowed the identification of a 27-item set satisfying the Rasch Model's requirements for fundamental measurement, with further confirmation of unidimensionality by post-hoc confirmatory factor analysis. The new scale (Unified Balance Scale) holds proven measurement properties and may be a candidate tool for "bed to community" balance measurement for patients with balance problems within the neuro-rehabilitation setting. Future studies are warranted to explore further its external validity and other clinical properties, as well as to improve its usability.

An analytical model of the mechanical properties of bulk coal under confined stress

Science.gov (United States)

Wang, G.X.; Wang, Z.T.; Rudolph, V.; Massarotto, P.; Finley, R.J.

2007-01-01

This paper presents the development of an analytical model which can be used to relate the structural parameters of coal to its mechanical properties such as elastic modulus and Poisson's ratio under a confined stress condition. This model is developed primarily to support process modeling of coalbed methane (CBM) or CO2-enhanced CBM (ECBM) recovery from coal seam. It applied an innovative approach by which stresses acting on and strains occurring in coal are successively combined in rectangular coordinates, leading to the aggregated mechanical constants. These mechanical properties represent important information for improving CBM/ECBM simulations and incorporating within these considerations of directional permeability. The model, consisting of constitutive equations which implement a mechanically consistent stress-strains correlation, can be used as a generalized tool to study the mechanical and fluid behaviors of coal composites. An example using the model to predict the stress-strain correlation of coal under triaxial confined stress by accounting for the elastic and brittle (non-elastic) deformations is discussed. The result shows a good agreement between the prediction and the experimental measurement. ?? 2007 Elsevier Ltd. All rights reserved.

Fatigue response of a PZT multilayer actuator under high-field electric cycling with mechanical preload

Science.gov (United States)

Wang, Hong; Wereszczak, Andrew A.; Lin, Hua-Tay

2009-01-01

An electric fatigue test system was developed for evaluating the reliability of piezoelectric actuators with a mechanical loading capability. Fatigue responses of a lead zirconate titanate (PZT) multilayer actuator with a platethrough electrode configuration were studied under an electric field (1.7 times that of the coercive field of PZT material) and a concurrent mechanical preload (30.0 MPa). A total of 109 cycles was carried out. Variations in charge density and mechanical strain under the high electric field and constant mechanical loads were observed during the fatigue test. The dc and the first harmonic (at 10 Hz) dielectric and piezoelectric coefficients were subsequently characterized using fast Fourier transformation. Both the dielectric and the piezoelectric coefficients exhibited a monotonic decrease prior to 2.86×108 cycles under certain preloading conditions, and then fluctuated. Both the dielectric loss tangent and the piezoelectric loss tangent also fluctuated after a decrease. The results are interpreted and discussed with respect to domain wall activities, microdefects, and other anomalies.

Simulation of fatigue damage in ferroelectric polycrystals under mechanical/electrical loading

Science.gov (United States)

Kozinov, S.; Kuna, M.

2018-07-01

The reliability of smart-structures made of ferroelectric ceramics is essentially reduced by the formation of cracks under the action of external electrical and/or mechanical loading. In the current research a numerical model for low-cycle fatigue in ferroelectric mesostructures is proposed. In the finite element simulations a combination of two user element routines is utilized. The first one is used to model a micromechanical ferroelectric domain switching behavior inside the grains. The second one is used to simulate fatigue damage of grain boundaries by a cohesive zone model (EMCCZM) based on an electromechanical cyclic traction-separation law (TSL). For numerical simulations a scanning electron microscope image of the ceramic's grain structure was digitalized and meshed. The response of this mesostructure to cyclic electrical or mechanical loading is systematically analyzed. As a result of the simulations, the distribution of electric potential, field, displacement and polarization as well as mechanical stresses and deformations inside the grains are obtained. At the grain boundaries, the formation and evolution of damage are analyzed until final failure and induced degradation of electric permittivity. It is found that the proposed model correctly mimics polycrystalline behavior during poling processes and progressive damage under cyclic electromechanical loading. To the authors' knowledge, it is the first model and numerical analysis of ferroelectric polycrystals taking into account both domain reorientation and cohesive modeling of intergranular fracture. It can help to understand failure mechanisms taking place in ferroelectrics during fatigue processes.

An investigation of the mechanism underlying teacher aggression : Testing I3 theory and the General Aggression Model

NARCIS (Netherlands)

Montuoro, Paul; Mainhard, Tim

2017-01-01

Background: Considerable research has investigated the deleterious effects of teachers responding aggressively to students who misbehave, but the mechanism underlying this dysfunctional behaviour remains unknown. Aims: This study investigated whether the mechanism underlying teacher aggression

Gifles de la Tourett's Disease a Single case study A Discussion on Aetiology and Treatment

Directory of Open Access Journals (Sweden)

C. Izadi

1978-01-01

Full Text Available A case of Gille de la Tourett's syndrome is reported and discussed 111 the light of conflicting views on the aetiology of the condition. It is hypothesized that if Tourette's syndrome is to be considered as a sort of reaction against adaption to an unhealthy environment, this reaction and its continuity can be attributed to permanent eNS damage (Probably in the area of corpora striata beginning in childhood. Treatment with haloperidol is suggested as a most effective method of symptomatic treatment.

Trends in the aetiology of facial fractures in the south of Ireland (1975-1993).

LENUS (Irish Health Repository)

Carroll, S M

2012-02-03

An aetiological review of 332 patients with facial fractures seen in a 1 year period (1993) was carried out and compared to a similar study of 266 patients, performed in this unit in 1975. Males predominated in both years. Two thirds of fractures occurred in the second and third decades. Road traffic accident (RTA) related facial fractures decreased from 27% of the total in 1975 to 17% in 1993. Assault related facial fractures increased from 18% of the total in 1975 to 27% in 1993. In both study periods nasal fractures were the most common facial fracture seen and sport was the most common cause of facial fracture. The number of patients undergoing surgery increased from 67% of the total to 79% over the same period.

Reliability Issues and Solutions in Flexible Electronics Under Mechanical Fatigue

Science.gov (United States)

Yi, Seol-Min; Choi, In-Suk; Kim, Byoung-Joon; Joo, Young-Chang

2018-03-01

Flexible devices are of significant interest due to their potential expansion of the application of smart devices into various fields, such as energy harvesting, biological applications and consumer electronics. Due to the mechanically dynamic operations of flexible electronics, their mechanical reliability must be thoroughly investigated to understand their failure mechanisms and lifetimes. Reliability issue caused by bending fatigue, one of the typical operational limitations of flexible electronics, has been studied using various test methodologies; however, electromechanical evaluations which are essential to assess the reliability of electronic devices for flexible applications had not been investigated because the testing method was not established. By employing the in situ bending fatigue test, we has studied the failure mechanism for various conditions and parameters, such as bending strain, fatigue area, film thickness, and lateral dimensions. Moreover, various methods for improving the bending reliability have been developed based on the failure mechanism. Nanostructures such as holes, pores, wires and composites of nanoparticles and nanotubes have been suggested for better reliability. Flexible devices were also investigated to find the potential failures initiated by complex structures under bending fatigue strain. In this review, the recent advances in test methodology, mechanism studies, and practical applications are introduced. Additionally, perspectives including the future advance to stretchable electronics are discussed based on the current achievements in research.

Biochemical mechanisms of signaling: perspectives in plants under arsenic stress.

Science.gov (United States)

Islam, Ejazul; Khan, Muhammad Tahir; Irem, Samra

2015-04-01

Plants are the ultimate food source for humans, either directly or indirectly. Being sessile in nature, they are exposed to various biotic and abiotic stresses because of changing climate that adversely effects their growth and development. Contamination of heavy metals is one of the major abiotic stresses because of anthropogenic as well as natural factors which lead to increased toxicity and accumulation in plants. Arsenic is a naturally occurring metalloid toxin present in the earth crust. Due to its presence in terrestrial and aquatic environments, it effects the growth of plants. Plants can tolerate arsenic using several mechanisms like phytochelation, vacuole sequestration and activation of antioxidant defense systems. Several signaling mechanisms have evolved in plants that involve the use of proteins, calcium ions, hormones, reactive oxygen species and nitric oxide as signaling molecules to cope with arsenic toxicity. These mechanisms facilitate plants to survive under metal stress by activating their defense systems. The pathways by which these stress signals are perceived and responded is an unexplored area of research and there are lots of gaps still to be filled. A good understanding of these signaling pathways can help in raising the plants which can perform better in arsenic contaminated soil and water. In order to increase the survival of plants in contaminated areas there is a strong need to identify suitable gene targets that can be modified according to needs of the stakeholders using various biotechnological techniques. This review focuses on the signaling mechanisms of plants grown under arsenic stress and will give an insight of the different sensory systems in plants. Furthermore, it provides the knowledge about several pathways that can be exploited to develop plant cultivars which are resistant to arsenic stress or can reduce its uptake to minimize the risk of arsenic toxicity through food chain thus ensuring food security. Copyright © 2015

Thermal stability of nafion membranes under mechanical stress

Energy Technology Data Exchange (ETDEWEB)

Quintilii, M; Struis, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-06-01

The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

Dynamic Response and Failure Mechanism of Brittle Rocks Under Combined Compression-Shear Loading Experiments

Science.gov (United States)

Xu, Yuan; Dai, Feng

2018-03-01

A novel method is developed for characterizing the mechanical response and failure mechanism of brittle rocks under dynamic compression-shear loading: an inclined cylinder specimen using a modified split Hopkinson pressure bar (SHPB) system. With the specimen axis inclining to the loading direction of SHPB, a shear component can be introduced into the specimen. Both static and dynamic experiments are conducted on sandstone specimens. Given carefully pulse shaping, the dynamic equilibrium of the inclined specimens can be satisfied, and thus the quasi-static data reduction is employed. The normal and shear stress-strain relationships of specimens are subsequently established. The progressive failure process of the specimen illustrated via high-speed photographs manifests a mixed failure mode accommodating both the shear-dominated failure and the localized tensile damage. The elastic and shear moduli exhibit certain loading-path dependence under quasi-static loading but loading-path insensitivity under high loading rates. Loading rate dependence is evidently demonstrated through the failure characteristics involving fragmentation, compression and shear strength and failure surfaces based on Drucker-Prager criterion. Our proposed method is convenient and reliable to study the dynamic response and failure mechanism of rocks under combined compression-shear loading.

Design options for cooperation mechanisms under the new European renewable energy directive

International Nuclear Information System (INIS)

Klessmann, Corinna; Lamers, Patrick; Ragwitz, Mario; Resch, Gustav

2010-01-01

In June 2009, a new EU directive on the promotion of renewable energy sources (RES) entered into effect. The directive 2009/28/EC, provides for three cooperation mechanisms that will allow member states to achieve their national RES target in cooperation with other member states: statistical transfer, joint projects, and joint support schemes. This article analyses the pros and cons of the three mechanisms and explores design options for their implementation through strategic and economic questions: How to counterbalance the major drawbacks of each mechanism? How to reflect a balance of costs and benefits between the involved member states? The analysis identifies a number of design options that respond to these questions, e.g. long term contracts to ensure sufficient flexibility for statistical transfers, a coordinated, standardised joint project approach to increase transparency in the European market, and a stepwise harmonisation of joint support schemes that is based on a cost-effective accounting approach. One conclusion is that the three cooperation mechanisms are closely interlinked. One can consider their relation to be a gradual transition from member state cooperation under fully closed national support systems in case of statistical transfers, to cooperation under fully open national support systems in a joint support scheme.

Mechanisms underlying the associations of maternal age with adverse perinatal outcomes

DEFF Research Database (Denmark)

Lawlor, Debbie A; Mortensen, Laust; Andersen, Anne-Marie Nybo

2011-01-01

The mechanisms underlying the association between maternal age (both young and older maternal age) and adverse perinatal outcomes are unclear. Methods We examined the association of maternal age at first birth with preterm birth (<37 weeks gestation) and small for gestational age (SGA) in a cohor...

Investigation of sheet steel St 37.2 under mechanical impact

International Nuclear Information System (INIS)

Berg, H.P.; Brennecke, P.; Koester, R.; Friehmelt, V.

1990-01-01

Special waste originating, e.g. from chemical industry and radioactive wastes are emplaced in disposal mines. Slinger stowing is an approved technique to fill up residual voids in emplacement rooms. If it should be applied, possible mechanical loads on the integrity of sheet steel containers have to be considered. By theoretical calculations and by experiments under variation of different parameters using test specimen and backfill material from the Konrad mine using the container type V as an example it has been shown that sheet steel St 37.2 with a wall thickness of 3 mm will withstand mechanical impact imposed by backfill particles having a speed of 24 m/s. (orig.) [de

A Study To Evaluate The Aetiological Factors And Management of Puberty Menorrhagia

Directory of Open Access Journals (Sweden)

Joydeb Roychowdhury

2008-04-01

Full Text Available Introduction: This study aims to evaluate the incidence, clinical presentation, etiological factors and treatment outcomes of the patients suffering from puberty menorrhagia. Methods: 65 patients with puberty menorrhagia attending the outpatient as well as indoor department of NRS Medical College, Kolkata during the period from February, 2005 to July,2006 were included in the study. They were prospectively analysed to assess the aetiological factors and the outcome of treatment required to manage these cases.Results – The incidence of puberty menorrhagia was 9.6% in our study. 40%s patients had menarche between 12-13 years. 61.6% had anovulatory dysfunctional uterine bleeding(DUB. 15.4% had hematological causes. Hypothyroidism, endometrial tuberculosis, polycystic ovarian disease were other important causes. 40% were relieved with tranexamic acid, 26% required hormone treatment and 35.3% received blood transfusion.Conclusion: Anovulatory DUB is the cause of menorrhagia in most of the cases .Medical treatment is mostly effective while surgical procedures are limited to few specific cases.

The frequency, characteristics and aetiology of stroke mimic presentations: a narrative review.

Science.gov (United States)

McClelland, Graham; Rodgers, Helen; Flynn, Darren; Price, Christopher I

2018-05-01

A significant proportion of patients with acute stroke symptoms have an alternative 'mimic' diagnosis. A narrative review was carried out to explore the frequency, characteristics and aetiology of stroke mimics. Prehospital and thrombolysis-treated patients were described separately. Overall, 9972 studies were identified from the initial search and 79 studies were included with a median stroke mimic rate of 19% (range: 1-64%). The prehospital median was 27% (range: 4-43%) and the thrombolysis median 10% (range: 1-25%). Seizures, migraines and psychiatric disorders are the most frequently reported causes of stroke mimics. Several characteristics are consistently associated with stroke mimics; however, they do not fully exclude the possibility of stroke. Nineteen per cent of suspected stroke patients had a mimic condition. Stroke mimics were more common with younger age and female sex. The range of mimic diagnoses, a lack of clear differentiating characteristics and the short treatment window for ischaemic stroke create challenges for early identification.

Investigation on the interaction of catalase with sodium lauryl sulfonate and the underlying mechanisms.

Science.gov (United States)

Wang, Jing; Jia, Rui; Wang, Jiaxi; Sun, Zhiqiang; Wu, Zitao; Liu, Rutao; Zong, Wansong

2018-02-01

As a classic type of anionic surfactants, sodium lauryl sulfonate (SLS) might change the structure and function of antioxidant enzyme catalase (CAT) through their direct interactions. However, the underlying molecular mechanism is still unknown. This study investigated the direct interaction of SLS with CAT molecule and the underlying mechanisms using multi-spectroscopic methods, isothermal titration calorimetry, and molecular docking studies. No obvious effects were observed on CAT structure and activity under low SLS concentration exposure. The particle size of CAT molecule decreased and CAT activity was slightly inhibited under high SLS concentration exposure. SLS prefers to bind to the interface of CAT mainly via van der Waals' forces and hydrogen bonds. Subsequently, SLS interacts with the amino acid residues around the heme groups of CAT via hydrophobic interactions and might inhibit CAT activity. © 2017 Wiley Periodicals, Inc.

Detecting method for crude oil price fluctuation mechanism under different periodic time series

International Nuclear Information System (INIS)

Gao, Xiangyun; Fang, Wei; An, Feng; Wang, Yue

2017-01-01

Highlights: • We proposed the concept of autoregressive modes to indicate the fluctuation patterns. • We constructed transmission networks for studying the fluctuation mechanism. • There are different fluctuation mechanism under different periodic time series. • Only a few types of autoregressive modes control the fluctuations in crude oil price. • There are cluster effects during the fluctuation mechanism of autoregressive modes. - Abstract: Current existing literatures can characterize the long-term fluctuation of crude oil price time series, however, it is difficult to detect the fluctuation mechanism specifically under short term. Because each fluctuation pattern for one short period contained in a long-term crude oil price time series have dynamic characteristics of diversity; in other words, there exhibit various fluctuation patterns in different short periods and transmit to each other, which reflects the reputedly complicate and chaotic oil market. Thus, we proposed an incorporated method to detect the fluctuation mechanism, which is the evolution of the different fluctuation patterns over time from the complex network perspective. We divided crude oil price time series into segments using sliding time windows, and defined autoregressive modes based on regression models to indicate the fluctuation patterns of each segment. Hence, the transmissions between different types of autoregressive modes over time form a transmission network that contains rich dynamic information. We then capture transmission characteristics of autoregressive modes under different periodic time series through the structure features of the transmission networks. The results indicate that there are various autoregressive modes with significantly different statistical characteristics under different periodic time series. However, only a few types of autoregressive modes and transmission patterns play a major role in the fluctuation mechanism of the crude oil price, and these

Impact of immunosuppression on incidence, aetiology and outcome of ventilator-associated lower respiratory tract infections.

Science.gov (United States)

Moreau, Anne-Sophie; Martin-Loeches, Ignacio; Povoa, Pedro; Salluh, Jorge; Rodriguez, Alejandro; Thille, Arnaud W; Diaz Santos, Emilio; Vedes, Elisa; Lobo, Suzana Margareth; Mégarbane, Bruno; Molero Silvero, Esperanza; Coelho, Luis; Argaud, Laurent; Sanchez Iniesta, Rafael; Labreuche, Julien; Rouzé, Anahita; Nseir, Saad

2018-03-01

The aim of this planned analysis of the prospective multinational TAVeM database was to determine the incidence, aetiology and impact on outcome of ventilator-associated lower respiratory tract infections (VA-LRTI) in immunocompromised patients.All patients receiving mechanical ventilation for >48 h were included. Immunocompromised patients (n=663) were compared with non-immunocompromised patients (n=2297).The incidence of VA-LRTI was significantly lower among immunocompromised than among non-immunocompromised patients (16.6% versus 24.2%; sub-hazard ratio 0.65, 95% CI 0.53-0.80; p<0.0001). Similar results were found regarding ventilator-associated tracheobronchitis (7.3% versus 11.6%; sub-hazard ratio 0.61, 95% CI 0.45-0.84; p=0.002) and ventilator-associated pneumonia (9.3% versus 12.7%; sub-hazard ratio 0.72, 95% CI 0.54-0.95; p=0.019). Among patients with VA-LRTI, the rates of multidrug-resistant bacteria (72% versus 59%; p=0.011) and intensive care unit mortality were significantly higher among immunocompromised than among non-immunocompromised patients (54% versus 30%; OR 2.68, 95% CI 1.78-4.02; p<0.0001). In patients with ventilator-associated pneumonia, mortality rates were higher among immunocompromised than among non-immunocompromised patients (64% versus 34%; p<0.001).Incidence of VA-LRTI was significantly lower among immunocompromised patients, but it was associated with a significantly higher mortality rate. Multidrug-resistant pathogens were more frequently found in immunocompromised patients with VA-LRTI. Copyright ©ERS 2018.

Lumbar Discectomy of a Patient of Mitral Stenosis with Chronic Atrial Fibrillation Under Epidural Anaesthesia

Directory of Open Access Journals (Sweden)

Vinaya R Kulkarni

2008-01-01

Full Text Available A 60-year-old female patient posted for discectomy of lumbar region L 3 -L 4 was accidently diagnosed to have chronic atrial fibrillation of rheumatic aetiology.This is a case report of this patient of critical mitral stenosis with mild mitral regurgitation with chronic atrial fibrillation managed successfully under lower thoracic epidural anaesthesia,in prone position without any compli-cation.

Mechanical properties of the human spinal cord under the compressive loading.

Science.gov (United States)

Karimi, Alireza; Shojaei, Ahmad; Tehrani, Pedram

2017-12-01

The spinal cord as the most complex and critical part of the human body is responsible for the transmission of both motor and sensory impulses between the body and the brain. Due to its pivotal role any types of physical injury in that disrupts its function following by shortfalls, including the minor motor and sensory malfunctions as well as complicate quadriplegia and lifelong ventilator dependency. In order to shed light on the injuries to the spinal cord, the application of the computational models to simulate the trauma impact loading to that are deemed required. Nonetheless, it has not been fulfilled since there is a paucity of knowledge about the mechanical properties of the spinal cord, especially the cervical one, under the compressive loading on the grounds of the difficulty in obtaining this tissue from the human body. This study was aimed at experimentally measuring the mechanical properties of the human cervical spinal cord of 24 isolated fresh samples under the unconfined compressive loading at a relatively low strain rate. The stress-strain data revealed the elastic modulus and maximum/failure stress of 40.12±6.90 and 62.26±5.02kPa, respectively. Owing to the nonlinear response of the spinal cord, the Yeoh, Ogden, and Mooney-Rivlin hyperelastic material models have also been employed. The results may have implications not only for understanding the linear elastic and nonlinear hyperelastic mechanical properties of the cervical spinal cord under the compressive loading, but also for providing a raw data for investigating the injury as a result of the trauma thru the numerical simulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Reliability-based optimization of maintenance scheduling of mechanical components under fatigue

Science.gov (United States)

Beaurepaire, P.; Valdebenito, M.A.; Schuëller, G.I.; Jensen, H.A.

2012-01-01

This study presents the optimization of the maintenance scheduling of mechanical components under fatigue loading. The cracks of damaged structures may be detected during non-destructive inspection and subsequently repaired. Fatigue crack initiation and growth show inherent variability, and as well the outcome of inspection activities. The problem is addressed under the framework of reliability based optimization. The initiation and propagation of fatigue cracks are efficiently modeled using cohesive zone elements. The applicability of the method is demonstrated by a numerical example, which involves a plate with two holes subject to alternating stress. PMID:23564979

Behavior of duplex stainless steel casting defects under mechanical loadings

International Nuclear Information System (INIS)

Jayet-Gendrot, S.; Gilles, P.

2000-01-01

Several components in the primary circuit of pressurized water reactors are made of cast duplex stainless steels. This material contains small casting defects, mainly shrinkage cavities, due to the manufacturing process. In safety analyses, the structural integrity of the components is studied under the most severe assumptions: presence of a large defect, accidental loadings and end-of-life material properties accounting for its thermal aging embrittlement at the service temperature. The casting defects are idealized as semi-circular surface cracks or notches that have envelope dimensions. In order to assess the real severity of the casting defects under mechanical loadings, an experimental program was carried out. It consisted of testing, under both cyclic and monotonic solicitations, three-point bend specimens containing either a natural defect (in the form of a localized cluster of cavities) or a machined notch having the dimensions of the cluster's envelope. The results show that shrinkage cavities are far less harmful than envelope notches thanks to the metal bridges between cavities. Under fatigue loadings, the generalized initiation of a cluster of cavities (defined when the cluster becomes a crack of the same global size) is reached for a number of cycles that is much higher than the one leading to the initiation of a notch. In the case of monotonic loadings, specimens with casting defects offer a very high resistance to ductile tearing. The tests are analyzed in order to develop a method that takes into account the behavior of casting defects in a more realistic fashion than by an envelope crack. Various approaches are investigated, including the search of equivalent defects or of criteria based on continuum mechanics concepts, and compared with literature data. This study shows the conservatism of current safety analyses in modeling casting defects by envelope semi-elliptical cracks and contributes to the development of alternative approaches. (orig.)

Contact force and mechanical loss of multistage cable under tension and bending

Science.gov (United States)

Ru, Yanyun; Yong, Huadong; Zhou, Youhe

2016-10-01

A theoretical model for calculating the stress and strain states of cabling structures with different loadings has been developed in this paper. We solve the problem for the first- and second-stage cable with tensile or bending strain. The contact and friction forces between the strands are presented by two-dimensional contact model. Several theoretical models have been proposed to verify the results when the triplet subjected to the tensile strain, including contact force, contact stresses, and mechanical loss. It is found that loadings will affect the friction force and the mechanical loss of the triplet. The results show that the contact force and mechanical loss are dependent on the twist pitch. A shorter twist pitch can lead to higher contact force, while the trend of mechanical loss with twist pitch is complicated. The mechanical loss may be reduced by adjusting the twist pitch reasonably. The present model provides a simple analysis method to investigate the mechanical behaviors in multistage-structures under different loads.

Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

Science.gov (United States)

2013-01-01

REPORT Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions 14. ABSTRACT 16. SECURITY...properties and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found in armor structures made of high...mechanisms, friction stir welding M. Grujicic, B. Pandurangan, A. Arakere, C-F. Yen, B. A. Cheeseman Clemson University Office of Sponsored Programs 300

Mechanisms underlying prorenin actions on hypothalamic neurons implicated in cardiometabolic control

Directory of Open Access Journals (Sweden)

Soledad Pitra

2016-10-01

Conclusions: We identified novel neuronal targets and cellular mechanisms underlying PR/PRR actions in critical hypothalamic neurons involved in cardiometabolic regulation. This fundamental mechanistic information regarding central PR/PRR actions is essential for the development of novel RAS-based therapeutic targets for the treatment of cardiometabolic disorders in obesity and hypertension.

Model test study of evaporation mechanism of sand under constant atmospheric condition

OpenAIRE

CUI, Yu Jun; DING, Wenqi; SONG, Weikang

2014-01-01

The evaporation mechanism of Fontainebleau sand using a large-scale model chamber is studied. First, the evaporation test on a layer of water above sand surface is performed under various atmospheric conditions, validating the performance of the chamber and the calculation method of actual evaporation rate by comparing the calculated and measured cumulative evaporations. Second,the evaporation test on sand without water layer is conducted under constant atmospheric condition. Both the evoluti...

The aetiological role of human papillomavirus in oesophageal squamous cell carcinoma: a meta-analysis.

Directory of Open Access Journals (Sweden)

Surabhi S Liyanage

Full Text Available BACKGROUND: The aetiological role of human papillomavirus (HPV in oesophageal squamous cell carcinoma (OSCC has been widely researched for more than three decades, with conflicting findings. In the absence of a large, adequately powered single case-control study, a meta-analysis of all available case-control studies is the most rigorous way of identifying any potential association between HPV and OSCC. We present the first global meta-analysis of case-control studies investigating the role of HPV in OSCC. METHODS: Case-control studies investigating OSCC tissue for presence of HPV DNA were identified. 21 case-control studies analyzing a total of 1223 cases and 1415 controls, met our inclusion criteria. HPV detection rates were tabulated for each study and all studies were assessed for quality. The random effects method was used to pool the odds ratios (OR. RESULTS: From all OSCC specimens included in this meta-analysis, 35% (426/1223 were positive for HPV DNA. The pooled OR for an HPV-OSCC association was 3.04 (95% CI 2.20 to 4.20. Meta-regression analysis did not find a significant association between OR and any of the quality domains. Influence analysis was non-significant for the effect of individual studies on the pooled estimate. Studies conducted in countries with low to medium OSCC incidence showed a stronger relationship (OR 4.65, 95% CI 2.47 to 8.76 than regions of high OSCC incidence (OR 2.65, 95% CI 1.80 to 3.91. CONCLUSIONS: Uncertainty around the aetiological role of HPV in OSCC is due largely to the small number and scale of appropriately designed studies. Our meta-analysis of these studies suggests that HPV increases the risk of OSCC three-fold. This study provides the strongest evidence to date of an HPV-OSCC association. The importance of these findings is that prophylactic vaccination could be of public health benefit in prevention of OSCC in countries with high OSCC incidence.

Chronic kidney disease of uncertain aetiology: prevalence and causative factors in a developing country.

Science.gov (United States)

Jayatilake, Nihal; Mendis, Shanthi; Maheepala, Palitha; Mehta, Firdosi R

2013-08-27

This study describes chronic kidney disease of uncertain aetiology (CKDu), which cannot be attributed to diabetes, hypertension or other known aetiologies, that has emerged in the North Central region of Sri Lanka. A cross-sectional study was conducted, to determine the prevalence of and risk factors for CKDu. Arsenic, cadmium, lead, selenium, pesticides and other elements were analysed in biological samples from individuals with CKDu and compared with age- and sex-matched controls in the endemic and non-endemic areas. Food, water, soil and agrochemicals from both areas were analysed for heavy metals. The age-standardised prevalence of CKDu was 12.9% (95% confidence interval [CI] = 11.5% to 14.4%) in males and 16.9% (95% CI = 15.5% to 18.3%) in females. Severe stages of CKDu were more frequent in males (stage 3: males versus females = 23.2% versus 7.4%; stage 4: males versus females = 22.0% versus 7.3%; P 39 years and those who farmed (chena cultivation) (OR [odds ratio] = 1.926, 95% CI = 1.561 to 2.376 and OR = 1.195, 95% CI = 1.007 to 1.418 respectively, P CKDu (1.039 μg/g) compared with controls in the endemic and non-endemic areas (0.646 μg/g, P CKDu stage (P CKDu were at levels known to cause kidney damage. Food items from the endemic area contained cadmium and lead above reference levels. Serum selenium was CKDu and pesticides residues were above reference levels in 31.6% of those with CKDu. These results indicate chronic exposure of people in the endemic area to low levels of cadmium through the food chain and also to pesticides. Significantly higher urinary excretion of cadmium in individuals with CKDu, and the dose-effect relationship between urine cadmium concentration and CKDu stages suggest that cadmium exposure is a risk factor for the pathogensis of CKDu. Deficiency of selenium and genetic susceptibility seen in individuals with CKDu suggest that they may be predisposing factors for the development of CKDu.

Contraction and elongation: Mechanics underlying cell boundary deformations in epithelial tissue.

Science.gov (United States)

Hara, Yusuke

2017-06-01

The cell-cell boundaries of epithelial cells form cellular frameworks at the apical side of tissues. Deformations in these boundaries, for example, boundary contraction and elongation, and the associated forces form the mechanical basis of epithelial tissue morphogenesis. In this review, using data from recent Drosophila studies on cell boundary contraction and elongation, I provide an overview of the mechanism underlying the bi-directional deformations in the epithelial cell boundary, that are sustained by biased accumulations of junctional and apico-medial non-muscle myosin II. Moreover, how the junctional tensions exist on cell boundaries in different boundary dynamics and morphologies are discussed. Finally, some future perspectives on how recent knowledge about single cell boundary-level mechanics will contribute to our understanding of epithelial tissue morphogenesis are discussed. © 2017 Japanese Society of Developmental Biologists.

Viral and bacterial aetiologies of male urethritis: findings of a high prevalence of Epstein-Barr virus.

Science.gov (United States)

Berntsson, M; Löwhagen, G-B; Bergström, T; Dubicanac, L; Welinder-Olsson, C; Alvengren, G; Tunbäck, P

2010-03-01

Male urethritis is one of the most common sexually transmitted infections (STIs). However, the aetiology is still unclear in many cases. In this study the prevalences of Epstein-Barr virus (EBV), herpes simplex virus type 1 (HSV-1), HSV-2, cytomegalovirus (CMV), adenovirus, Chlamydia trachomatis, Mycoplasma genitalium and Ureaplasma urealyticum (including subtyping) were investigated. Samples from 112 male STI attendants with microscopically verified urethritis and from a control group of 103 men without clinical or microscopic signs of urethritis were analysed. Prevalences in the urethritis group compared with the controls were as follows: EBV 21%, 6% (P urethritis and may play a role in its pathogenesis.

The Mediated MIMIC Model for Understanding the Underlying Mechanism of DIF

Science.gov (United States)

Cheng, Ying; Shao, Can; Lathrop, Quinn N.

2016-01-01

Due to its flexibility, the multiple-indicator, multiple-causes (MIMIC) model has become an increasingly popular method for the detection of differential item functioning (DIF). In this article, we propose the mediated MIMIC model method to uncover the underlying mechanism of DIF. This method extends the usual MIMIC model by including one variable…

Mechanical Behaviour of Bolted Joints Under Impact Rates of Loading

Science.gov (United States)

2012-01-01

M. (1995). Bearing Strength of Autoclave and oven cured kevlar / epoxy laminates under static and dynamic loading. Compostes, 451-456. Kretsis, G...Joints in Glass Fibre/ Epoxy Laminates. Composites, Volume 16. No 2. Kolsky, H. (1949). An Investigation of the Mechanical Properties of Materials at...elongating the pulse width. The responses are read by the strain gages bonded on the incident and transmission bar with Vishay AE-10 epoxy . The gages

Neural mechanisms underlying cognitive control of men with lifelong antisocial behavior.

Science.gov (United States)

Schiffer, Boris; Pawliczek, Christina; Mu Ller, Bernhard; Forsting, Michael; Gizewski, Elke; Leygraf, Norbert; Hodgins, Sheilagh

2014-04-30

Results of meta-analyses suggested subtle deficits in cognitive control among antisocial individuals. Because almost all studies focused on children with conduct problems or adult psychopaths, however, little is known about cognitive control mechanisms among the majority of persistent violent offenders who present an antisocial personality disorder (ASPD). The present study aimed to determine whether offenders with ASPD, relative to non-offenders, display dysfunction in the neural mechanisms underlying cognitive control and to assess the extent to which these dysfunctions are associated with psychopathic traits and trait impulsivity. Participants comprised 21 violent offenders and 23 non-offenders who underwent event-related functional magnetic resonance imaging while performing a non-verbal Stroop task. The offenders, relative to the non-offenders, exhibited reduced response time interference and a different pattern of conflict- and error-related activity in brain areas involved in cognitive control, attention, language, and emotion processing, that is, the anterior cingulate, dorsolateral prefrontal, superior temporal and postcentral cortices, putamen, thalamus, and amygdala. Moreover, between-group differences in behavioural and neural responses revealed associations with core features of psychopathy and attentional impulsivity. Thus, the results of the present study confirmed the hypothesis that offenders with ASPD display alterations in the neural mechanisms underlying cognitive control and that those alterations relate, at least in part, to personality characteristics. Copyright © 2014. Published by Elsevier Ireland Ltd.

A cross-sectional study on aetiology of diarrhoeal disease, India

Directory of Open Access Journals (Sweden)

S Purwar

2016-01-01

Full Text Available Background: Global, regional and national estimates clearly place diarrhoeal diseases as a major, albeit to an extant neglected public health problem. Deaths of children aged <5 years owing to diarrhoea was estimated to be 1.87 million at the global level (uncertainty range from 1.56 to 2.19 million, which is approximately 19% of total child deaths. Objectives: The present report is a cross-sectional study undertaken to estimate the role of various aetiological agents causing diarrhoea in North Karnataka and adjoining areas of Maharashtra and Goa. Methods: Three hundred stool samples were collected from patients seeking health care at KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, Belgaum; and processed for detection of various bacterial, viral and parasitic agents. Results: Bacterial pathogens attributed to 65.7% of diarrhoea cases, followed by viral infection (22%, parasitic infection (16.3% and infection by Candida spp. (5.6%. The study identified Escherichia coli in general and Enteropathogenic E. coli in particular, and Group A Rotavirus to be the most frequently isolated pathogens among diarrhoea patients. Conclusion: The data generated from the current study will help the health officials for better interventional and treatment strategies for diarrhoeal diseases.

Unraveling the mechanisms underlying postural instability in Parkinson's disease using dynamic posturography

NARCIS (Netherlands)

Nonnekes, J.H.; Kam, D. de; Geurts, A.C.; Weerdesteijn, V.G.M.; Bloem, B.R.

2013-01-01

Postural instability, one of the cardinal symptoms of Parkinson's disease (PD), has devastating consequences for affected patients. Better strategies to prevent falls are needed, but this calls for an improved understanding of the complex mechanisms underlying postural instability. We must also

Feeding Problems and Their Underlying Mechanisms in the Esophageal Atresia–Tracheoesophageal Fistula Patient

Science.gov (United States)

Mahoney, Lisa; Rosen, Rachel

2017-01-01

Feeding difficulties such as dysphagia, coughing, choking, or vomiting during meals, slow eating, oral aversion, food refusal, and stressful mealtimes are common in children with repaired esophageal atresia (EA) and the reasons for this are often multifactorial. The aim of this review is to describe the possible underlying mechanisms contributing to feeding difficulties in patients with EA and approaches to management. Underlying mechanisms for these feeding difficulties include esophageal dysphagia, oropharyngeal dysphagia and aspiration, and aversions related to prolonged gastrostomy tube feeding. The initial diagnostic evaluation for feeding difficulties in a patient with EA may involve an esophagram, videofluoroscopic imaging or fiberoptic endoscopic evaluation during swallowing, upper endoscopy with biopsies, pH-impedance testing, and/or esophageal motility studies. The main goal of management is to reduce the factors contributing to feeding difficulties and may include reducing esophageal stasis, maximizing reflux therapies, treating underlying lung disease, dilating strictures, and altering feeding methods, routes, or schedules. PMID:28620597

[Study on mechanism of SOM stabilization of paddy soils under long-term fertilizations].

Science.gov (United States)

Luo, Lu; Zhou, Ping; Tong, Cheng-Li; Shi, Hui; Wu, Jin-Shui; Huang, Tie-Ping

2013-02-01

Fourier transform infrared spectroscopy (FTIR) was applied to study the structure of soil organic matter (SOM) of paddy soils under long-term different fertilization treatments. The aim was to clarify the different distribution of SOM between different fertilization methods and between topsoil and subsoil, and to explore the stability mechanism of SOM under different fertilization treatments. The results showed that the content of topsoil organic carbon (SOC) was the highest under organic-inorganic fertilizations, with the increment of SOC by 18.5%, 12.9% and 18.4% under high organic manure (HOM), low organic manure (LOM) and straw returning (STW) respectively compared with no fertilization treatment (CK). The long-term fertilizations also changed the chemical structure of SOM. As compared with CK, different fertilization treatments increased the functional group absorbing intensity of chemical resistance compounds (aliphatic, aromaticity), carbohydrate and organo-silicon compounds, which was the most distinctive under treatments of HOM, LOM and STW. For example, the absorbing intensity of alkyl was 0.30, 0.25 and 0.29 under HOM, LOM and STW, respectively. These values were increased by 87% , 56% and 81% as compared with that under CK treatment. The functional group absorbing intensity of SOM in the topsoil was stronger than that in the subsoil, with the most distinctive difference under HOM, LOM and STW treatments. The present research indicated that the enhanced chemical resistance of functional group of SOM may contribute to the high contents of SOC in the paddy soils under long-term organic-inorganic fertilizations, which also suggested a chemical stabilization mechanism of SOM in the paddy soils.

Mechanical properties of cellulose electro-active paper under different environmental conditions

International Nuclear Information System (INIS)

Kim, Heung Soo; Kim, Jaehwan; Jung, Woochul; Ampofo, Joshua; Craft, William; Sankar, Jagannathan

2008-01-01

The mechanical properties of cellulose-based electro-active paper (EAPap) are investigated under various environmental conditions. Cellulose EAPap has been discovered as a smart material that can be used as both sensor and actuator. Its advantages include low voltage operation, light weight, low power consumption, biodegradability and low cost. EAPap is made with cellulose paper coated with thin electrodes. EAPap shows a reversible and reproducible bending movement as well as longitudinal displacement under an electric field. However, EAPap is a complex anisotropic material which has not been fully characterized. This study investigates the mechanical properties of cellulose-based EAPap, including Young's modulus, yield strength, ultimate strength and creep, along with orientation directions, humidity and temperature levels. To test the materials in different humidity and temperature levels, a special material testing system was made that can control the testing environmental conditions. The initial Young's modulus of EAPap is in the range of 4–9 GPa, which was higher than that of other polymer materials. Also, the Young's modulus is orientation dependent, which may be associated with the piezoelectricity of EAPap materials. The elastic strength and stiffness gradually decreased when the humidity and temperature were increased. Creep and relaxation were observed under constant stress and strain, respectively. Through scanning electron microscopy, EAPap is shown to exhibit both layered and oriented cellulose macromolecular structures that impact both the elastic and plastic behavior

Beginning of a journey: unraveling the mystery of chronic kidney disease of unknown aetiology (CKDu) in Sri Lanka.

Science.gov (United States)

Kumaresan, Jacob; Seneviratne, Ruwanika

2017-06-30

Globally, chronic kidney disease of unknown aetiology (CKDu) is observed in several areas and among specific ethnic or occupational groups. Given the widespread environmental pollution and the proportions of agriculture workers world-wide, CKDu may be the next global public health issue demanding attention. Recent escalation of CKDu in Sri Lanka has caused a serious public health crisis in the country, made worse by lack of national data. The specific geographic distribution, preponderance among farming population, similar histology findings and absence of usual risk factors for kidney disease indicate undetected nephrotoxic agents playing a role in causation. Some of the challenges for the country are uncoordinated preventive efforts, diverse opinions among stakeholders on causality and fragmented research efforts with limited focus on potential causes of CKDu. As a result, accurate estimation of the CKDu burden, identification of causative agents and implementation of effective actions have been delayed. Stakeholder engagement, with involvement of international experts has been the starting point for finalizing a working case definition to establish community based surveillance as a future platform to conduct long-term research. The country is now poised to contribute to global knowledge by solving the mystery of 'u' in CKDu. This commentary highlights the importance and the mechanisms of making an effective breakthrough as early as possible; failing which CKDu can progress rapidly as demonstrated by the situation in Sri Lanka.

Deterioration of mechanical properties of high strength structural steel S460N under transient state fire condition

International Nuclear Information System (INIS)

Qiang, Xuhong; Bijlaard, Frans S.K.; Kolstein, Henk

2012-01-01

Highlights: ► Mechanical properties of S460N under transient state fire condition are obtained. ► Elevated-temperature mechanical properties of steels are dependent on steel grades. ► No design standard is applicable to HSS S460N under transient state fire condition. ► Specific statements on various HSS in fire should be proposed in design standards. ► Research results offer accurate material property for structural design engineers. -- Abstract: 911 World Trade Centre Tragedy put fire safety of constructional steel structures into question. Since then, more and more research attention has been paid to the elevated-temperature mechanical properties of structural steels, which is a critical basis of evaluating the fire performance of steel structures. In the literature the available mechanical properties of structural steels under fire conditions were mainly obtained from steady state test method, as steady state test method is easier to perform than transient state test method and offers stress–strain curves directly. However, the transient state fire condition is considered to be more realistic to represent the real condition when constructions are exposed to fire. In order to reveal the deterioration of mechanical properties of the commonly used high strength structural steel S460N under transient state fire condition, tensile tests were conducted under various constant stress levels up to 800 MPa. The reduction factors of elastic modulus, yield and ultimate strengths of S460N under transient state fire condition were obtained and compared with current leading design standards and available literature. The application of such accurate elevated-temperature mechanical properties reduction factors of S460N can ensure a safe fire-resistance design and evaluation of steel structures with high strength steel S460N under transient state fire condition. This experimental study also supports other relative research on fire performance of steel structures with

[Aetiology and pathogenesis of damages to blood vessels in drug addicts].

Science.gov (United States)

Sultanaliev, T A; Tursynbaev, S E; Ivakin, V M

2007-01-01

The article deals with the problems concerning aetiology and pathogenesis of damages to blood vessels in patients practicing parenteral administration of surrogates of narcotic substances. In order to clinically and experimentally study the pattern of morphological alterations in the area of narcotic substances administration and to work out an appropriate classification of the forms and stages of development of the pathological process, the authors analysed the clinical course of vascular lesions and complications thereof in a total of 244 drug abusers having parenterally administered surrogates of narcotic substances and undergoing treatment at the Department of Vascular Surgery of the Municipal Clinical Hospital of the city of Almaty. Additionally, experimental studies were carried out on 16 rabbits with the induced model of parenteral administration of surrogates of narcotic substances, thus making it possible to study the degree of their effect and to confirm the theory of a chemical impact of the homemade drugs on the vascular wall. The findings of the carried out studies enabled us to single out the following clinical stages of vascular lesions: stage I - the initial stage of cicatricial-and-ulcerous lesions formation, stage II - formation of cutaneous-and-vascular fistulas, stage III - the stage of complications characterized by development of health-hazardous vascular lesions, i. e., arterial and venous thromboses of the major vessels, as well as arrosive bleedings. It was noted that more than 50% of patients were admitted to the clinic presenting with the third stage of vascular lesions. The experimental part of the study included 64 experiments on 16 rabbits (one experiment per each paw of the animal). The laboratory animals were subdivided into three groups. The first experimental group consisted of the rabbits with a mechanically inflicted injury to the vessels. The second and third experimental groups were composed of the rabbits having received

How diagnostic tests help to disentangle the mechanisms underlying neuropathic pain symptoms in painful neuropathies.

Science.gov (United States)

Truini, Andrea; Cruccu, Giorgio

2016-02-01

Neuropathic pain, ie, pain arising directly from a lesion or disease affecting the somatosensory afferent pathway, manifests with various symptoms, the commonest being ongoing burning pain, electrical shock-like sensations, and dynamic mechanical allodynia. Reliable insights into the mechanisms underlying neuropathic pain symptoms come from diagnostic tests documenting and quantifying somatosensory afferent pathway damage in patients with painful neuropathies. Neurophysiological investigation and skin biopsy studies suggest that ongoing burning pain primarily reflects spontaneous activity in nociceptive-fiber pathways. Electrical shock-like sensations presumably arise from high-frequency ectopic bursts generated in demyelinated, nonnociceptive, Aβ fibers. Although the mechanisms underlying dynamic mechanical allodynia remain debatable, normally innocuous stimuli might cause pain by activating spared and sensitized nociceptive afferents. Extending the mechanistic approach to neuropathic pain symptoms might advance targeted therapy for the individual patient and improve testing for new drugs.

Mechanisms of astrocytic K(+) clearance and swelling under high extracellular K(+) concentrations.

Science.gov (United States)

Murakami, Shingo; Kurachi, Yoshihisa

2016-03-01

In response to the elevation of extracellular K(+) concentration ([K(+)]out), astrocytes clear excessive K(+) to maintain conditions necessary for neural activity. K(+) clearance in astrocytes occurs via two processes: K(+) uptake and K(+) spatial buffering. High [K(+)]out also induces swelling in astrocytes, leading to edema and cell death in the brain. Despite the importance of astrocytic K(+) clearance and swelling, the underlying mechanisms remain unclear. Here, we report results from a simulation analysis of astrocytic K(+) clearance and swelling. Astrocyte models were constructed by incorporating various mechanisms such as intra/extracellular ion concentrations of Na(+), K(+), and Cl(-), cell volume, and models of Na,K-ATPase, Na-K-Cl cotransporter (NKCC), K-Cl cotransporter, inwardly-rectifying K(+) (KIR) channel, passive Cl(-) current, and aquaporin channel. The simulated response of astrocyte models under the uniform distribution of high [K(+)]out revealed significant contributions of NKCC and Na,K-ATPase to increases of intracellular K(+) and Cl(-) concentrations, and swelling. Moreover, we found that, under the non-uniform distribution of high [K(+)]out, KIR channels localized at synaptic clefts absorbed excess K(+) by depolarizing the equivalent potential of K(+) (E K) above membrane potential, while K(+) released through perivascular KIR channels was enhanced by hyperpolarizing E K and depolarizing membrane potential. Further analysis of simulated drug effects revealed that astrocyte swelling was modulated by blocking each of the ion channels and transporters. Our simulation analysis revealed controversial mechanisms of astrocytic K(+) clearance and swelling resulting from complex interactions among ion channels and transporters.

Aetiological bases of 46,XY disorders of sex development in the Hong Kong Chinese population.

Science.gov (United States)

Chan, Angel O K; But, W M; Lee, C Y; Lam, Y Y; Ng, K L; Loung, P Y; Lam, Aimen; Cheng, C W; Shek, C C; Wong, W S; Wong, K F; Wong, M Y; Tse, W Y

2015-12-01

Disorders of sex development are due to congenital defects in chromosomal, gonadal, or anatomical sex development. The objective of this study was to determine the aetiology of this group of disorders in the Hong Kong Chinese population. Five public hospitals in Hong Kong. Patients with 46,XY disorders of sex development under the care of paediatric endocrinologists between July 2009 and June 2011. Measurement of serum gonadotropins, adrenal and testicular hormones, and urinary steroid profiling. Mutational analysis of genes involved in sexual differentiation by direct DNA sequencing and multiplex ligation-dependent probe amplification. Overall, 64 patients were recruited for the study. Their age at presentation ranged from birth to 17 years. The majority presented with ambiguous external genitalia including micropenis and severe hypospadias. A few presented with delayed puberty and primary amenorrhea. Baseline and post-human chorionic gonadotropin-stimulated testosterone and dihydrotestosterone levels were not discriminatory in patients with or without AR gene mutations. Of the patients, 22 had a confirmed genetic disease, with 11 having 5α-reductase 2 deficiency, seven with androgen insensitivity syndrome, one each with cholesterol side-chain cleavage enzyme deficiency, Frasier syndrome, NR5A1-related sex reversal, and persistent Müllerian duct syndrome. Our findings suggest that 5α-reductase 2 deficiency and androgen insensitivity syndrome are possibly the two most common causes of 46,XY disorders of sex development in the Hong Kong Chinese population. Since hormonal findings can be unreliable, mutational analysis of the SRD5A2 and AR genes should be considered the first-line tests for these patients.

Anxiety, bulimia, drug and alcohol addiction, depression, and schizophrenia: what do you think about their aetiology, dangerousness, social distance, and treatment? A latent class analysis approach

NARCIS (Netherlands)

Mannarini, S.; Boffo, M.

2015-01-01

PURPOSE: Mental illness stigma is a serious societal problem and a critical impediment to treatment seeking for mentally ill people. To improve the understanding of mental illness stigma, this study focuses on the simultaneous analysis of people's aetiological beliefs, attitudes (i.e. perceived

Viral aetiology of wheezing in children under five

Directory of Open Access Journals (Sweden)

Prithi Sureka Mummidi

2017-01-01

Interpretation & conclusions: The study reported the presence of respiratory viral agents in 28.57 per cent of children with wheezing; RSV and PIV were most common, accounting to 55 per cent of the total cases. Mixed infection was reported in 30 per cent of cases. Seasonal variation in the occurrence of these viruses was also noted. Further studies need to be done with a large sample and longer follow up period to verify these findings.

Microscale failure mechanisms leading to internal short circuit in Li-ion batteries under complex loading scenarios

NARCIS (Netherlands)

Sahraei, E.; Bosco, E.; Dixon, B.; Lai, B.

2016-01-01

One of the least understood mechanisms of Li-ion batteries is the development of internal short circuits under mechanical loads. In this study, a micro mechanical model is developed and subjected to various loading scenarios to understand the sequence of failure in the multi-layer, multi-material

Evolution of the bonding mechanism of ZnO under isotropic compression: A first-principles study

International Nuclear Information System (INIS)

Zhou, G.C.; Sun, L.Z.; Wang, J.B.; Zhong, X.L.; Zhou, Y.C.

2008-01-01

The electronic structure and the bonding mechanism of ZnO under isotropic pressure have been studied by using the full-potential linear augmented plane wave (FP-LAPW) method within the density-functional theory (DFT) based on LDA+U exchange correlation (EXC) potential. We used the theory of Atoms in Molecules (AIM) method to analyze the change of the charge transfer and the bonding strength under isotropic pressure. The results of the theoretical analysis show that charge transfer between Zn and O atomic basins nearly linearly increases with the increasing pressure. Charge density along the Zn-O bond increases under the high pressure. The bonding strength and the ionicity of Zn-O bond also increase with the increasing pressure. The linear evolution process of the bonding mechanism under isotropic pressure was shown clearly in the present paper

The pathologic mechanisms underlying lumbar distraction spinal cord injury in rabbits.

Science.gov (United States)

Wu, Di; Zheng, Chao; Wu, Ji; Xue, Jing; Huang, Rongrong; Wu, Di; Song, Yueming

2017-11-01

A reliable experimental rabbit model of distraction spinal cord injury (SCI) was established to successfully simulate gradable and replicable distraction SCI. However, further research is needed to elucidate the pathologic mechanisms underlying distraction SCI. The aim of this study was to investigate the pathologic mechanisms underlying lumbar distraction SCI in rabbits. This is an animal laboratory study. Using a self-designed spine distractor, the experimental animals were divided into a control group and 10%, 20%, and 30% distraction groups. Pathologic changes to the spinal cord microvessels in the early stage of distraction SCI were identified by perfusion of the spinal cord vasculature with ink, production of transparent specimens, observation by light microscopy, and observation of corrosion casts of the spinal cord microvascular architecture by scanning electron microscopy. Malondialdehyde (MDA) and superoxide dismutase (SOD) concentrations in the injured spinal cord tissue were measured after 8 hours. With an increasing degree and duration of distraction, the spinal cord microvessels were only partially filled and had the appearance of spasm until rupture and hemorrhage were observed. The MDA concentration increased and the SOD concentration decreased in the spinal cord tissue. Changes to the internal and external spinal cord vessels led to spinal cord ischemia, which is a primary pathologic mechanism of distraction SCI. Lipid peroxidation mediated by free radicals took part in secondary pathologic damage of distraction SCI. Copyright © 2017 Elsevier Inc. All rights reserved.

[Neurohumoral mechanisms for vasovagal syncopes. Part I].

Science.gov (United States)

Gajek, Jacek; Zyśko, Dorota

2003-04-01

Vasovagal syncope is defined as a reflex loss of consciousness related to reaction to various stimuli as orthostatic stress, pain or emotions connected with loss of muscle postural tone. The aetiology of this disorder is still unknown. The imbalance between the parts of autonomic nervous system and other homeostasis-related systems as renin-angiotensin-aldosterone system, peptides as endothelin, neuropeptide Y, vasopressin, adrenomedullin and cAMP, adenosine and AMP can play an important role in the development of vasovagal syncope. In the first part of the paper the authors describe the mechanisms involved in the development of vasovagal reaction, pathophysiology of the head-up tilt test and the role of autonomic nervous system.

Mechanisms for closing bores and releasably securing articles within the bores under longitudinal load

International Nuclear Information System (INIS)

Klahn, F.C.; Nolan, J.H.; Wills, C.

1979-01-01

This invention relates to mechanisms for closing bores of tubular passages and for releasably securing articles within the bores under longitudinal load. The system includes an axially movable latch, an actuator and locking devices. Embodiments of the invention can be used as closure mechanisms for tubular irradiation surveillance specimen assembly holders used in nuclear reactors. (UK)

Mechanisms for closing bores and releasably securing articles within the bores under longitudinal load

International Nuclear Information System (INIS)

Kalen, D.D.; Mitchem, J.W.

1979-01-01

This invention relates to mechanisms for closing bores of tubular passages and for releasably securing articles within the bores under longitudinal load. The system includes an axially movable actuator and a latch which engages the tubular opening. Embodiments of the invention can be used as closure mechanisms for tubular irradiation surveillance specimen assembly holders used in nuclear reactors. (UK)

Nonlinear Dynamic Analysis of Telescopic Mechanism for Truss Structure Bridge Inspection Vehicle Under Pedestrian Excitation

Directory of Open Access Journals (Sweden)

Wenwen Sui

Full Text Available Abstract Nonlinear dynamic analysis of an axially moving telescopic mechanism for truss structure bridge inspection vehicle under pedestrian excitation is carried out. A biomechanically inspired inverted-pendulum model is utilized to simplify the pedestrian. The nonlinear equations of motion for the beam-pedestrian system are derived using the Hamilton's principle. The equations are transformed into two ordinary differential equations by applying the Galerkin's method at the first two orders. The solutions to the equations are acquired by using the Newmark-β method associated with the Newton-Raphson method. The time-dependent feature of the eigenfunctions for the two beams are taken into consideration in the solutions. Accordingly, the equations of motion for a simplified system, in which the pedestrian is regarded as moving cart, are given. In the numerical examples, dynamic responses of the telescopic mechanism in eight conditions of different beam-telescoping and pedestrian-moving directions are simulated. Comparisons between the vibrations of the beams under pedestrian excitation and corresponding moving cart are carried out to investigate the influence of the pedestrian excitation on the telescopic mechanism. The results show that the displacement of the telescopic mechanism under pedestrian excitation is smaller than that under moving cart especially when the pedestrian approaches the beams end. Additionally, compared with moving cart, the pedestrian excitation can effectively strengthen the vibration when the beam extension is small or when the pedestrian is close to the beams end.

An Investigation of the Mechanism Underlying Teacher Aggression: Testing I[superscript 3] Theory and the General Aggression Model

Science.gov (United States)

Montuoro, Paul; Mainhard, Tim

2017-01-01

Background: Considerable research has investigated the deleterious effects of teachers responding aggressively to students who misbehave, but the mechanism underlying this dysfunctional behaviour remains unknown. Aims: This study investigated whether the mechanism underlying teacher aggression follows I[superscript 3] theory or General Aggression…

Cyclic life of superalloy IN738LC under in-phase and out-of-phase thermo-mechanical fatigue loading

International Nuclear Information System (INIS)

Chen Hongjun; Wahi, R.P.; Wever, H.

1995-01-01

The cyclic life of IN738LC, a widely used nickel base superalloy for blades in stationary gas turbines, was investigated under thermo-mechanical fatigue loading using a temperature variation range of 1023 to 1223 K, with temperature variation rate in the range of 6 to 15 K/min. Simple thermo-mechanical cycles with linear sequences corresponding to in-phase (IP) and out-of-phase (OP) tests were performed. Both the IP and OP tests were carried out at different constant mechanical strain ranges varied between 0.8 to 2.0% and at a constant mechanical strain rate of 10 -5 s -1 . Thermo-mechanical fatigue lives under both test conditions were compared with each other and with those of isothermal LCF tests at a temperature of 1223 K. The results show that the life under thermo-mechanical fatigue is strongly dependent on the nature of the test, i.e. stress controlled or strain controlled. (orig.)

Bacterial Aetiology and Antibiotic Resistance Pattern of Community-Acquired Urinary Tract Infections in Children in a Tertiary Care Hospital in Bangladesh

Directory of Open Access Journals (Sweden)

Lazina Sharmin

2017-09-01

Full Text Available Background: Urinary tract infections (UTIs in children are among the most common bacterial infections. Community-acquired urinary tract infections (CAUTI are often treated empirically with broad-spectrum antibiotics. Pattern of aetiologic agents and their antibiotic sensitivity may vary according to geographical and regional location. So, knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Objectives: To determine the common bacterial aetiologies of CAUTIs and their antibiotic resistance patterns in a tertiary care hospital, Savar. Materials and Methods: This cross-sectional descriptive study was conducted at Enam Medical College Hospital, Savar from May 2016 to April 2017. We collected clean-catch mid-stream urine samples from 257 patients having clinical diagnosis of UTI and submitted to the clinical microbiology laboratory for culture and sensitivity. Results: A total of 120 (46.7% samples were positive for bacterial growth. Escherichia coli (79% was the most common pathogen, followed by Klebsiella spp. (14%. Bacterial isolates showed high prevalence of resistance to multiple antibiotics. Resistance against amoxicillin/clavulanic acid, co-trimoxazole and ciprofloxacin was higher compared to newer quinolones and aminoglycosides. Conclusion: Esch. coli and Klebsiella spp. were the predominant bacterial pathogens. The resistance pattern to commonly prescribed antibiotics was quite high and alarming.

Aetiology and mechanisms of injury in medial tibial stress syndrome: Current and future developments

OpenAIRE

Franklyn, Melanie; Oakes, Barry

2015-01-01

Medial tibial stress syndrome (MTSS) is a debilitating overuse injury of the tibia sustained by individuals who perform recurrent impact exercise such as athletes and military recruits. Characterised by diffuse tibial anteromedial or posteromedial surface subcutaneous periostitis, in most cases it is also an injury involving underlying cortical bone microtrauma, although it is not clear if the soft tissue or cortical bone reaction occurs first. Nuclear bone scans and magnetic resonance imagin...

Nanomaterials modulate stem cell differentiation: biological interaction and underlying mechanisms.

Science.gov (United States)

Wei, Min; Li, Song; Le, Weidong

2017-10-25

Stem cells are unspecialized cells that have the potential for self-renewal and differentiation into more specialized cell types. The chemical and physical properties of surrounding microenvironment contribute to the growth and differentiation of stem cells and consequently play crucial roles in the regulation of stem cells' fate. Nanomaterials hold great promise in biological and biomedical fields owing to their unique properties, such as controllable particle size, facile synthesis, large surface-to-volume ratio, tunable surface chemistry, and biocompatibility. Over the recent years, accumulating evidence has shown that nanomaterials can facilitate stem cell proliferation and differentiation, and great effort is undertaken to explore their possible modulating manners and mechanisms on stem cell differentiation. In present review, we summarize recent progress in the regulating potential of various nanomaterials on stem cell differentiation and discuss the possible cell uptake, biological interaction and underlying mechanisms.

Mechanisms Underlying HIV-Associated Noninfectious Lung Disease.

Science.gov (United States)

Presti, Rachel M; Flores, Sonia C; Palmer, Brent E; Atkinson, Jeffrey J; Lesko, Catherine R; Lau, Bryan; Fontenot, Andrew P; Roman, Jesse; McDyer, John F; Twigg, Homer L

2017-11-01

Pulmonary disease remains a primary source of morbidity and mortality in persons living with HIV (PLWH), although the advent of potent combination antiretroviral therapy has resulted in a shift from predominantly infectious to noninfectious pulmonary complications. PLWH are at high risk for COPD, pulmonary hypertension, and lung cancer even in the era of combination antiretroviral therapy. The underlying mechanisms of this are incompletely understood, but recent research in both human and animal models suggests that oxidative stress, expression of matrix metalloproteinases, and genetic instability may result in lung damage, which predisposes PLWH to these conditions. Some of the factors that drive these processes include tobacco and other substance use, direct HIV infection and expression of specific HIV proteins, inflammation, and shifts in the microbiome toward pathogenic and opportunistic organisms. Further studies are needed to understand the relative importance of these factors to the development of lung disease in PLWH. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Neural mechanisms underlying human consensus decision-making.

Science.gov (United States)

Suzuki, Shinsuke; Adachi, Ryo; Dunne, Simon; Bossaerts, Peter; O'Doherty, John P

2015-04-22

Consensus building in a group is a hallmark of animal societies, yet little is known about its underlying computational and neural mechanisms. Here, we applied a computational framework to behavioral and fMRI data from human participants performing a consensus decision-making task with up to five other participants. We found that participants reached consensus decisions through integrating their own preferences with information about the majority group members' prior choices, as well as inferences about how much each option was stuck to by the other people. These distinct decision variables were separately encoded in distinct brain areas-the ventromedial prefrontal cortex, posterior superior temporal sulcus/temporoparietal junction, and intraparietal sulcus-and were integrated in the dorsal anterior cingulate cortex. Our findings provide support for a theoretical account in which collective decisions are made through integrating multiple types of inference about oneself, others, and environments, processed in distinct brain modules. Copyright © 2015 Elsevier Inc. All rights reserved.

Autophagy as a Possible Underlying Mechanism of Nanomaterial Toxicity

Directory of Open Access Journals (Sweden)

Vanessa Cohignac

2014-07-01

Full Text Available The rapid development of nanotechnologies is raising safety concerns because of the potential effects of engineered nanomaterials on human health, particularly at the respiratory level. Since the last decades, many in vivo studies have been interested in the pulmonary effects of different classes of nanomaterials. It has been shown that some of them can induce toxic effects, essentially depending on their physico-chemical characteristics, but other studies did not identify such effects. Inflammation and oxidative stress are currently the two main mechanisms described to explain the observed toxicity. However, the exact underlying mechanism(s still remain(s unknown and autophagy could represent an interesting candidate. Autophagy is a physiological process in which cytoplasmic components are digested via a lysosomal pathway. It has been shown that autophagy is involved in the pathogenesis and the progression of human diseases, and is able to modulate the oxidative stress and pro-inflammatory responses. A growing amount of literature suggests that a link between nanomaterial toxicity and autophagy impairment could exist. In this review, we will first summarize what is known about the respiratory effects of nanomaterials and we will then discuss the possible involvement of autophagy in this toxicity. This review should help understand why autophagy impairment could be taken as a promising candidate to fully understand nanomaterials toxicity.

The 1st Baltic Osseointegration Academy and Lithuanian University of Health Sciences Consensus Conference 2016. Summary and Consensus Statements: Group I - Peri-Implantitis Aetiology, Risk Factors and Pathogenesis

Directory of Open Access Journals (Sweden)

Claudio Stacchi

2016-09-01

Full Text Available Introduction: The task of Group 1 was to review and update the existing data concerning aetiology, risk factors and pathogenesis of peri-implantitis. Previous history of periodontitis, poor oral hygiene, smoking and presence of general diseases have been considered among the aetiological risk factors for the onset of peri-implant pathologies, while late dental implant failures are commonly associated with peri-implantitis and/or with the application of incorrect biomechanical forces. Special interest was paid to the bone cells dynamics as part of the pathogenesis of peri-implantitis. Material and Methods: The main areas indagated by this group were as follows: influence of smoking, history of periodontitis and general diseases on peri-implantitis development, bio-mechanics of implant loading and its influence on peri-implant bone and cellular dynamics related to the pathogenesis of peri-implantitis. The systematic reviews and/or meta-analyses were registered in PROSPERO, an international prospective register of systematic reviews: http://www.crd.york.ac.uk/PROSPERO/. The literature in the corresponding areas of interest was screened and reported following the PRISMA (Preferred Reporting Item for Systematic Review and Meta-Analysis Statement: http://www.prisma-statement.org/. Method of preparation of the systematic reviews, based on comprehensive search strategies, was discussed and standardized. The summary of the materials and methods employed by the authors in preparing the systematic reviews and/or meta-analyses is presented in Preface chapter. Results: The results and conclusions of the review process are presented in the respective papers. One systematic review with meta-analysis, three systematic reviews and one theoretical analysis were performed. The group′s general commentaries, consensus statements, clinical recommendations and implications for research are presented in this article.

Understanding and imitating unfamiliar actions: distinct underlying mechanisms.

Directory of Open Access Journals (Sweden)

Joana C Carmo

Full Text Available The human "mirror neuron system" has been proposed to be the neural substrate that underlies understanding and, possibly, imitating actions. However, since the brain activity with mirror properties seems insufficient to provide a good description for imitation of actions outside one's own repertoire, the existence of supplementary processes has been proposed. Moreover, it is unclear whether action observation requires the same neural mechanisms as the explicit access to their meaning. The aim of this study was two-fold as we investigated whether action observation requires different processes depending on 1 whether the ultimate goal is to imitate or understand the presented actions and 2 whether the to-be-imitated actions are familiar or unfamiliar to the subject. Participants were presented with both meaningful familiar actions and meaningless unfamiliar actions that they had to either imitate or discriminate later. Event-related Potentials were used as differences in brain activity could have been masked by the use of other techniques with lower temporal resolution. In the imitation task, a sustained left frontal negativity was more pronounced for meaningless actions than for meaningful ones, starting from an early time-window. Conversely, observing unfamiliar versus familiar actions with the intention of discriminating them led to marked differences over right centro-posterior scalp regions, in both middle and latest time-windows. These findings suggest that action imitation and action understanding may be sustained by dissociable mechanisms: while imitation of unfamiliar actions activates left frontal processes, that are likely to be related to learning mechanisms, action understanding involves dedicated operations which probably require right posterior regions, consistent with their involvement in social interactions.

The mechanism underlying fast germination of tomato cultivar LA2711.

Science.gov (United States)

Yang, Rongchao; Chu, Zhuannan; Zhang, Haijun; Li, Ying; Wang, Jinfang; Li, Dianbo; Weeda, Sarah; Ren, Shuxin; Ouyang, Bo; Guo, Yang-Dong

2015-09-01

Seed germination is important for early plant morphogenesis as well as abiotic stress tolerance, and is mainly controlled by the phytohormones abscisic acid (ABA) and gibberellic acid (GA). Our previous studies identified a salt-tolerant tomato cultivar, LA2711, which is also a fast-germinating genotype, compared to its salt-sensitive counterpart, ZS-5. In an effort to further clarify the mechanism underlying this phenomenon, we compared the dynamic levels of ABA and GA4, the transcript abundance of genes involved in their biosynthesis and catabolism as well as signal transduction between the two cultivars. In addition, we tested seed germination sensitivity to ABA and GAs. Our results revealed that insensitivity of seed germination to exogenous ABA and low ABA content in seeds are the physiological mechanisms conferring faster germination rates of LA2711 seeds. SlCYP707A2, which encodes an ABA catabolic enzyme, may play a decisive role in the fast germination rate of LA2711, as it showed a significantly higher level of expression in LA2711 than ZS-5 at most time points tested during germination. The current results will enable us to gain insight into the mechanism(s) regarding seed germination of tomato and the role of fast germination in stress tolerance. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Handedness is related to neural mechanisms underlying hemispheric lateralization of face processing

Science.gov (United States)

Frässle, Stefan; Krach, Sören; Paulus, Frieder Michel; Jansen, Andreas

2016-06-01

While the right-hemispheric lateralization of the face perception network is well established, recent evidence suggests that handedness affects the cerebral lateralization of face processing at the hierarchical level of the fusiform face area (FFA). However, the neural mechanisms underlying differential hemispheric lateralization of face perception in right- and left-handers are largely unknown. Using dynamic causal modeling (DCM) for fMRI, we aimed to unravel the putative processes that mediate handedness-related differences by investigating the effective connectivity in the bilateral core face perception network. Our results reveal an enhanced recruitment of the left FFA in left-handers compared to right-handers, as evidenced by more pronounced face-specific modulatory influences on both intra- and interhemispheric connections. As structural and physiological correlates of handedness-related differences in face processing, right- and left-handers varied with regard to their gray matter volume in the left fusiform gyrus and their pupil responses to face stimuli. Overall, these results describe how handedness is related to the lateralization of the core face perception network, and point to different neural mechanisms underlying face processing in right- and left-handers. In a wider context, this demonstrates the entanglement of structurally and functionally remote brain networks, suggesting a broader underlying process regulating brain lateralization.

Inflammatory aetiology of human myometrial activation tested using directed graphs.

Directory of Open Access Journals (Sweden)

2005-07-01

Full Text Available THERE ARE THREE MAIN HYPOTHESES FOR THE ACTIVATION OF THE HUMAN UTERUS AT LABOUR: functional progesterone withdrawal, inflammatory stimulation, and oxytocin receptor activation. To test these alternatives we have taken information and data from the literature to develop causal pathway models for the activation of human myometrium. The data provided quantitative RT-PCR results on key genes from samples taken before and during labour. Principal component analysis showed that pre-labour samples form a homogenous group compared to those during labour. We therefore modelled the alternative causal pathways in non-labouring samples using directed graphs and statistically compared the likelihood of the different models using structural equations and D-separation approaches. Using the computer program LISREL, inflammatory activation as a primary event was highly consistent with the data (p = 0.925, progesterone withdrawal, as a primary event, is plausible (p = 0.499, yet comparatively unlikely, oxytocin receptor mediated initiation is less compatible with the data (p = 0.091. DGraph, a software program that creates directed graphs, produced similar results (p= 0.684, p= 0.280, and p = 0.04, respectively. This outcome supports an inflammatory aetiology for human labour. Our results demonstrate the value of directed graphs in determining the likelihood of causal relationships in biology in situations where experiments are not possible.

Asymmetric migration of human keratinocytes under mechanical stretch and cocultured fibroblasts in a wound repair model.

Directory of Open Access Journals (Sweden)

Dongyuan Lü

Full Text Available Keratinocyte migration during re-epithelization is crucial in wound healing under biochemical and biomechanical microenvironment. However, little is known about the underlying mechanisms whereby mechanical tension and cocultured fibroblasts or keratinocytes modulate the migration of keratinocytes or fibroblasts. Here we applied a tensile device together with a modified transwell assay to determine the lateral and transmembrane migration dynamics of human HaCaT keratinocytes or HF fibroblasts. A novel pattern of asymmetric migration was observed for keratinocytes when they were cocultured with non-contact fibroblasts, i.e., the accumulative distance of HaCaT cells was significantly higher when moving away from HF cells or migrating from down to up cross the membrane than that when moving close to HF cells or when migrating from up to down, whereas HF migration was symmetric. This asymmetric migration was mainly regulated by EGF derived from fibroblasts, but not transforming growth factor α or β1 production. Mechanical stretch subjected to fibroblasts fostered keratinocyte asymmetric migration by increasing EGF secretion, while no role of mechanical stretch was found for EGF secretion by keratinocytes. These results provided a new insight into understanding the regulating mechanisms of two- or three-dimensional migration of keratinocytes or fibroblasts along or across dermis and epidermis under biomechanical microenvironment.

Inspection Mechanism and Experimental Study of Prestressed Reverse Tension Method under PC Beam Bridge Anchorage

Science.gov (United States)

Peng, Zhang

2018-03-01

the prestress under anchorage is directly related to the structural security and performance of PC beam bridge. The reverse tension method is a kind of inspection which confirms the prestress by exerting reversed tension load on the exposed prestressing tendon of beam bridge anchoring system. The thesis elaborately expounds the inspection mechanism and mechanical effect of reverse tension method, theoretically analyzes the influential elements of inspection like tool anchorage deformation, compression of conjuncture, device glide, friction of anchorage loop mouth and elastic compression of concrete, and then presents the following formula to calculate prestress under anchorage. On the basis of model experiment, the thesis systematically studies some key issues during the reverse tension process of PC beam bridge anchorage system like the formation of stress-elongation curve, influential factors, judgment method of prestress under anchorage, variation trend and compensation scale, verifies the accuracy of mechanism analysis and demonstrates: the prestress under anchorage is less than or equal to 75% of the ultimate strength of prestressing tendon, the error of inspect result is less than 1%, which can meet with the demands of construction. The research result has provided theoretical basis and technical foundation for the promotion and application of reverse tension in bridge construction.

Behavioral Effects of Upper Respiratory Tract Illnesses: A Consideration of Possible Underlying Cognitive Mechanisms

Directory of Open Access Journals (Sweden)

Andrew P. Smith

2012-03-01

Full Text Available Previous research has shown that both experimentally induced upper respiratory tract illnesses (URTIs and naturally occurring URTIs influence mood and performance. The present study investigated possible cognitive mechanisms underlying the URTI-performance changes. Those who developed a cold (N = 47 had significantly faster, but less accurate, performance than those who remained healthy (N = 54. Illness had no effect on manipulations designed to influence encoding, response organisation (stimulus-response compatilibility or response preparation. Similarly, there was no evidence that different components of working memory were impaired. Overall, the present research confirms that URTIs can have an effect on performance efficiency. Further research is required to identify the physiological and behavioral mechanisms underlying these effects.

Exact solution for stresses/displacements in a multilayered hollow cylinder under thermo-mechanical loading

International Nuclear Information System (INIS)

Yeo, W.H.; Purbolaksono, J.; Aliabadi, M.H.; Ramesh, S.; Liew, H.L.

2017-01-01

In this study, a new analytical solution by the recursive method for evaluating stresses/displacements in multilayered hollow cylinder under thermo-mechanical loading was developed. The results for temperature distribution, displacements and stresses obtained by using the proposed solution were shown to be in good agreement with the FEM results. The proposed analytical solution was also found to produce more accurate results than those by the analytical solution reported in literature. - Highlights: • A new analytical solution for evaluating stresses in multilayered hollow cylinder under thermo-mechanical loading. • A simple computational procedure using a recursive method. • A promising technique for evaluating the operating axial and hoop stresses in pressurized composite vessels.

Bell's palsy: aetiology, clinical features and multidisciplinary care.

Science.gov (United States)

Eviston, Timothy J; Croxson, Glen R; Kennedy, Peter G E; Hadlock, Tessa; Krishnan, Arun V

2015-12-01

Bell's palsy is a common cranial neuropathy causing acute unilateral lower motor neuron facial paralysis. Immune, infective and ischaemic mechanisms are all potential contributors to the development of Bell's palsy, but the precise cause remains unclear. Advancements in the understanding of intra-axonal signal molecules and the molecular mechanisms underpinning Wallerian degeneration may further delineate its pathogenesis along with in vitro studies of virus-axon interactions. Recently published guidelines for the acute treatment of Bell's palsy advocate for steroid monotherapy, although controversy exists over whether combined corticosteroids and antivirals may possibly have a beneficial role in select cases of severe Bell's palsy. For those with longstanding sequaelae from incomplete recovery, aesthetic, functional (nasal patency, eye closure, speech and swallowing) and psychological considerations need to be addressed by the treating team. Increasingly, multidisciplinary collaboration between interested clinicians from a wide variety of subspecialties has proven effective. A patient centred approach utilising physiotherapy, targeted botulinum toxin injection and selective surgical intervention has reduced the burden of long-term disability in facial palsy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Severe hyperthyroidism: aetiology, clinical features and treatment outcome.

Science.gov (United States)

Iglesias, P; Dévora, O; García, J; Tajada, P; García-Arévalo, C; Díez, J J

2010-04-01

Severe hyperthyroidism (SH) is a serious medical disorder that can compromise life. There have not been systematic studies in which SH has been evaluated in detail. Here, our aims were: (1) to analyse both clinical and analytical features and outcome in patients with SH and (2) to compare these data with those found in more usual forms of hyperthyroidism. Patients and methods All patients diagnosed of SH (free thyroxine, FT4 > 100 pmol/l, NR: 11-23) seen in our endocrinology clinic in the last 15 years were studied and compared with a sample of patients with mild (mH; FT4, 23-50 pmol/l) and moderate (MH; FT4, 51-100 pmol/l) hyperthyroidism. Aetiology, clinical analytical and imaging data at diagnosis, therapeutic response and outcome were registered. Results A total of 107 patients with overt hyperthyroidism (81 females, mean age +/- SD 46.9 +/- 16.1 years) were evaluated. We studied a historic group with SH (n = 21; 14 females, 40.9 +/- 17.2 years) and, as a comparator group, we analyszed the data of 86 hyperthyroid patients (67 females, 48.4 +/- 15.5.6 years, NS) comparable in age and gender. The comparator group was classified in MH (n = 37, 26 females, 47.2 +/- 16.6 years) and mH (n = 49, 41 females, 49.4 +/- 14.8 years). In comparison with mH group, SH patients were significantly (P hyperthyroidism. FT4 was the only independent predictor of cure [OR 0.98 (CI 95%, 0.97-0.99), P hyperthyroidism is usually de novo and is accompanied by more clinical signs, symptoms, and analytical derangements, as well as higher titres of TRAb at diagnosis than milder forms of hyperthyroidism. The present data are not able to show differences in treatment modality, time to achieve cure, and remission rate among patients with mild, moderate and severe hyperthyroidism.

Discontinuity of the incudo-stapedial joint within a fully aerated middle ear and mastoid on computed tomography: A clinico-radiological study of its aetiology and clinical consequence

International Nuclear Information System (INIS)

Connor, S.E.J.; Pai, I.; Jiang, D.; Spiers, A.J.D.; Fitzgerald-O'Connor, A.

2012-01-01

Aim: To investigate the aetiology and clinical consequences of incudo-stapedial (IS) discontinuity when it is demonstrated on computed tomography (CT) within a fully aerated middle ear and mastoid. Methods and materials: Patients with CT evidence of IS discontinuity within a fully aerated middle ear and mastoid were prospectively identified. Clinical history, otoscopic findings, audiometry, and CT data were evaluated. Predefined criteria were used to determine the likely aetiology of IS discontinuity, whether it was diagnosed prior to the CT study, and the clinical consequences in terms of degree of conductive hearing loss and requirement for surgical correction. The range of CT appearances was evaluated. Results: The IS discontinuity in 34/36 ears was felt to be due to incus erosion secondary to chronic otitis, on the basis of clinical history and otoscopic findings. The IS discontinuity was rarely evident prior to CT with long-process deficiency being identified in only 5/36 cases. The mean air bone gap was only 22.5 dB. The ossicular defect was surgically addressed in only four cases. The incus deficiency was confined to the lower-third on CT in 19/36 cases. Conclusion: When IS discontinuity is demonstrated within a fully aerated middle ear and mastoid, the most likely aetiology is of acquired incus erosion due to chronic otitis media. The IS discontinuity on CT is usually not evident otoscopically. It usually results in only mild conductive hearing loss and the ossicular discontinuity was rarely surgically addressed in the present series.

Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

KAUST Repository

Cheng, Yingchun

2012-10-01

The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon–heptagon pairs (from hexagon–hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

KAUST Repository

Cheng, Yingchun; Schwingenschlö gl, Udo; Zhu, Zhiyong

2012-01-01

The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon–heptagon pairs (from hexagon–hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

Clinical manifestation and aetiology of a genital associated disease in Olive baboons (Papio hamadryas anubis) at Lake Manyara National Park, Tanzania

OpenAIRE

Knauf, Sascha

2011-01-01

The aim of the study was to investigate a genitally associated disease and to describe its clinical manifestation and aetiology in baboons at Lake Manyara National Park in the United Republic of Tanzania. Lake Manyara National Park is located in the northern part of the country, 160 km northwest of the Mt. Kilimanjaro. It is among the smallest protected areas, but belongs to the extended ecosystem of the Serengeti, Ngorongoro Conservation Area, Lake Manyara and Tarangire National Park. The...

New developments on the neurobiological and pharmaco-genetic mechanisms underlying internet and videogame addiction.

Science.gov (United States)

Weinstein, Aviv; Lejoyeux, Michel

2015-03-01

There is emerging evidence that the psychobiological mechanisms underlying behavioral addictions such as internet and videogame addiction resemble those of addiction for substances of abuse. Review of brain imaging, treatment and genetic studies on videogame and internet addiction. Literature search of published articles between 2009 and 2013 in Pubmed using "internet addiction" and "videogame addiction" as the search word. Twenty-nine studies have been selected and evaluated under the criteria of brain imaging, treatment, and genetics. Brain imaging studies of the resting state have shown that long-term internet game playing affected brain regions responsible for reward, impulse control and sensory-motor coordination. Brain activation studies have shown that videogame playing involved changes in reward and loss of control and that gaming pictures have activated regions similarly to those activated by cue-exposure to drugs. Structural studies have shown alterations in the volume of the ventral striatum possible as result of changes in reward. Furthermore, videogame playing was associated with dopamine release similar in magnitude to those of drugs of abuse and that there were faulty inhibitory control and reward mechanisms videogame addicted individuals. Finally, treatment studies using fMRI have shown reduction in craving for videogames and reduced associated brain activity. Videogame playing may be supported by similar neural mechanisms underlying drug abuse. Similar to drug and alcohol abuse, internet addiction results in sub-sensitivity of dopamine reward mechanisms. Given the fact that this research is in its early stage it is premature to conclude that internet addiction is equivalent to substance addictions. © American Academy of Addiction Psychiatry.

Ablation characteristics and reaction mechanism of insulation materials under slag deposition condition

Science.gov (United States)

Guan, Yiwen; Li, Jiang; Liu, Yang

2017-07-01

Current understanding of the physical and chemical processes involved in the ablation of insulation materials by highly aluminized solid propellants is limited. The study on the heat transfer and ablation principle of ethylene propylene diene monomer (EPDM) materials under slag deposition condition is essential for future design or modification of large solid rocket motors (SRMs) for launch application. In this paper, the alumina liquid flow pattern and the deposition principle in full-scale SRM engines are discussed. The interaction mechanism between the alumina droplets and the wall are analyzed. Then, an experimental method was developed to simulate the insulation material ablation under slag deposition condition. Experimental study was conducted based on a laboratory-scale device. Meanwhile, from the analysis of the cross-sectional morphology and chemical composition of the charring layer after ablation, the reaction mechanism of the charring layer under deposition condition was discussed, and the main reaction equation was derived. The numerical simulation and experimental results show the following. (i) The alumina droplet flow in the deposition section of the laboratory-scale device is similar to that of a full-scale SRM. (ii) The charring layer of the EPDM insulator displays a porous tight/loose structure under high-temperature slag deposition condition. (iii) A seven-step carbothermal reduction in the alumina is derived and established under high-pressure and high-temperature environment in the SRM combustion chamber. (iv) The analysis using thermodynamic software indicates that the reaction of the alumina and charring layer initially forms Al4C3 during the operation. Then, Al element and Al2OC compound are subsequently produced with the reduction in the release of gas CO as well with continuous environmental heating.

The aetiologies of central nervous system infections in hospitalised Cambodian children.

Science.gov (United States)

Turner, Paul; Suy, Kuong; Tan, Le Van; Sar, Pora; Miliya, Thyl; Hong, Nguyen Thi Thu; Hang, Vu Thi Ty; Ny, Nguyen Thi Han; Soeng, Sona; Day, Nicholas P J; van Doorn, H Rogier; Turner, Claudia

2017-12-29

Central nervous system (CNS) infections are an important cause of childhood morbidity and mortality. The aetiologies of these potentially vaccine-preventable infections have not been well established in Cambodia. We did a one year prospective study of children hospitalised with suspected CNS infection at Angkor Hospital for Children, Siem Reap. Cerebrospinal fluid specimens (CSF) samples underwent culture, multiplex PCR and serological analysis to identify a range of bacterial and viral pathogens. Viral metagenomics was performed on a subset of pathogen negative specimens. Between 1st October 2014 and 30th September 2015, 284 analysable patients were enrolled. The median patient age was 2.6 years; 62.0% were aged <5 years. CSF white blood cell count was ≥10 cells/μL in 116/272 (42.6%) cases. CNS infection was microbiologically confirmed in 55 children (19.3%). Enteroviruses (21/55), Japanese encephalitis virus (17/55), and Streptococcus pneumoniae (7/55) accounted for 45 (81.8%) of all pathogens identified. Of the pathogens detected, 74.5% (41/55) were viruses and 23.6% (13/55) were bacteria. The majority of patients were treated with ceftriaxone empirically. The case fatality rate was 2.5%. Enteroviruses, JEV and S. pneumoniae are the most frequently detected causes of CNS infection in hospitalised Cambodian children.

From Sound to Significance: Exploring the Mechanisms Underlying Emotional Reactions to Music.

Science.gov (United States)

Juslin, Patrik N; Barradas, Gonçalo; Eerola, Tuomas

2015-01-01

A common approach to studying emotional reactions to music is to attempt to obtain direct links between musical surface features such as tempo and a listener's responses. However, such an analysis ultimately fails to explain why emotions are aroused in the listener. In this article we explore an alternative approach, which aims to account for musical emotions in terms of a set of psychological mechanisms that are activated by different types of information in a musical event. This approach was tested in 4 experiments that manipulated 4 mechanisms (brain stem reflex, contagion, episodic memory, musical expectancy) by selecting existing musical pieces that featured information relevant for each mechanism. The excerpts were played to 60 listeners, who were asked to rate their felt emotions on 15 scales. Skin conductance levels and facial expressions were measured, and listeners reported subjective impressions of relevance to specific mechanisms. Results indicated that the target mechanism conditions evoked emotions largely as predicted by a multimechanism framework and that mostly similar effects occurred across the experiments that included different pieces of music. We conclude that a satisfactory account of musical emotions requires consideration of how musical features and responses are mediated by a range of underlying mechanisms.

Molecular Mechanisms Underlying the Epileptogenesis and Seizure Progression in Tuberous Sclerosis Complex 1 Deficient Mouse Models

Science.gov (United States)

2016-10-01

dysregulation in epileptogenesis in the developing brain? 2) What are the molecular mechanisms downstream of mTOR hyperactivation that trigger epileptogenesis...underlying epilepsy. Hopefully, a knowledge of these mechanisms will aid in a rational development of therapies. KEYWORDS Tuberous Sclerosis, Epilepsy

Mechanical stress analysis for a fuel rod under normal operating conditions

International Nuclear Information System (INIS)

Pino, Eddy S.; Giovedi, Claudia; Serra, Andre da Silva; Abe, Alfredo Y.

2013-01-01

Nuclear reactor fuel elements consist mainly in a system of a nuclear fuel encapsulated by a cladding material subject to high fluxes of energetic neutrons, high operating temperatures, pressure systems, thermal gradients, heat fluxes and with chemical compatibility with the reactor coolant. The design of a nuclear reactor requires, among a set of activities, the evaluation of the structural integrity of the fuel rod submitted to different loads acting on the fuel rod and the specific properties (dimensions and mechanical and thermal properties) of the cladding material and coolant, including thermal and pressure gradients produced inside the rod due to the fuel burnup. In this work were evaluated the structural mechanical stresses of a fuel rod using stainless steel as cladding material and UO 2 with a low degree of enrichment as fuel pellet on a PWR (pressurized water reactor) under normal operating conditions. In this sense, tangential, radial and axial stress on internal and external cladding surfaces considering the orientations of 0 deg, 90 deg and 180 deg were considered. The obtained values were compared with the limit values for stress to the studied material. From the obtained results, it was possible to conclude that, under the expected normal reactor operation conditions, the integrity of the fuel rod can be maintained. (author)

Uncovering the underlying physical mechanisms of biological systems via quantification of landscape and flux

International Nuclear Information System (INIS)

Xu Li; Chu Xiakun; Yan Zhiqiang; Zheng Xiliang; Zhang Kun; Zhang Feng; Yan Han; Wu Wei; Wang Jin

2016-01-01

In this review, we explore the physical mechanisms of biological processes such as protein folding and recognition, ligand binding, and systems biology, including cell cycle, stem cell, cancer, evolution, ecology, and neural networks. Our approach is based on the landscape and flux theory for nonequilibrium dynamical systems. This theory provides a unifying principle and foundation for investigating the underlying mechanisms and physical quantification of biological systems. (topical review)

Age differences in the underlying mechanisms of stereotype threat effects.

Science.gov (United States)

Popham, Lauren E; Hess, Thomas M

2015-03-01

The goals of the present study were to (a) examine whether age differences exist in the mechanisms underlying stereotype threat effects on cognitive performance and (b) examine whether emotion regulation abilities may buffer against threat effects on performance. Older and younger adults were exposed to positive or negative age-relevant stereotypes, allowing us to examine the impact of threat on regulatory focus and working memory. Self-reported emotion regulation measures were completed prior to the session. Older adults' performance under threat suggested a prevention-focused approach to the task, indexed by increased accuracy and reduced speed. The same pattern was observed in younger adults, but the effects were not as strong. Age differences emerged when examining the availability of working memory resources under threat, with young adults showing decrements, whereas older adults did not. Emotion regulation abilities moderated threat effects in young adults but not in older adults. The results provide support for the notion that stereotype threat may lead to underperformance through somewhat different pathways in older and younger adults. Future research should further examine whether the underlying reason for this age difference is rooted in age-related improvements in emotion regulation. © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Transformational Leadership and Organizational Citizenship Behavior: A Meta-Analytic Test of Underlying Mechanisms.

Science.gov (United States)

Nohe, Christoph; Hertel, Guido

2017-01-01

Based on social exchange theory, we examined and contrasted attitudinal mediators (affective organizational commitment, job satisfaction) and relational mediators (trust in leader, leader-member exchange; LMX) of the positive relationship between transformational leadership and organizational citizenship behavior (OCB). Hypotheses were tested using meta-analytic path models with correlations from published meta-analyses (761 samples with 227,419 individuals overall). When testing single-mediator models, results supported our expectations that each of the mediators explained the relationship between transformational leadership and OCB. When testing a multi-mediator model, LMX was the strongest mediator. When testing a model with a latent attitudinal mechanism and a latent relational mechanism, the relational mechanism was the stronger mediator of the relationship between transformational leadership and OCB. Our findings help to better understand the underlying mechanisms of the relationship between transformational leadership and OCB.

Mechanisms underlying epithelium-dependent relaxation in rat bronchioles

DEFF Research Database (Denmark)

Kroigaard, Christel; Dalsgaard, Thomas; Simonsen, Ulf

2010-01-01

This study investigated the mechanisms underlying epithelium-derived hyperpolarizing factor (EpDHF)-type relaxation in rat bronchioles. Immunohistochemistry was performed, and rat bronchioles and pulmonary arteries were mounted in microvascular myographs for functional studies. An opener of small...... (SK(Ca)) and intermediate (IK(Ca))-conductance calcium-activated potassium channels, NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime) was used to induce EpDHF-type relaxation. IK(Ca) and SK(Ca)3 positive immunoreactions were observed mainly in the epithelium and endothelium of bronchioles and arteries......, respectively. In 5-hydroxytryptamine (1 microM)-contracted bronchioles (828 +/- 20 microm, n = 84) and U46619 (0.03 microM)-contracted arteries (720 +/- 24 microm, n = 68), NS309 (0.001-10 microM) induced concentration-dependent relaxations that were reduced by epithelium/endothelium removal and by blocking IK...

Imitation in Newborn Infants: Exploring the Range of Gestures Imitated and the Underlying Mechanisms.

Science.gov (United States)

Meltzoff, Andrew N.; Moore, M. Keith

1989-01-01

Evaluated psychological mechanisms underlying imitation of facial actions in 40 newborn infants. Results showed imitation of head movement and a tongue-protrusion gesture. Subjects imitated from memory after displays had stopped. (RJC)

Deformation mechanisms in Ti/TiN multilayer under compressive loading

International Nuclear Information System (INIS)

Yang, Wei; Ayoub, Georges; Salehinia, Iman; Mansoor, Bilal; Zbib, Hussein

2017-01-01

The promising mechanical, physical and chemical properties of nano-scale metal/ceramic multilayers (MCMs) are of high interest for extreme environment applications. Understanding the plastic deformation mechanisms and the variables affecting those properties is therefore essential. The interface characteristics and the plastic deformation mechanisms under compressive loading in a Ti/TiN multilayer with a semi-coherent interface are numerically investigated. The interface structure of the Ti/TiN interface and the interface misfit dislocation were characterized using molecular dynamic simulations combined with atomically informed Frank-Bilby method. Three possible atomic stacking interface structures are identified according to the crystallographic analysis of the interface. Upon relaxation, large interface areas are occupied with the energetically stable configuration. Furthermore, the higher energy stacking are transformed into misfit dislocations or dislocation nodes. The molecular dynamic compressive stress strain response of the Ti/TiN multilayers exhibited three distinctive peaks. The first peak was generated by the dislocation dissociation of perfect dislocation into pairs of partials dislocation around extended nodes region at the interface. Upon further compression the second peak, identified as the first yielding, resulted from the activation of pyramidal slip planes in the Ti layer. Finally, a third peak identified as the second yielding, occurred when dislocation nucleated/transmitted in/into the TiN layer.

Genetic testing of aetiology of intellectual disability in a dedicated physical healthcare outpatient clinic for adults with intellectual disability.

Science.gov (United States)

Wallace, R A

2016-02-01

No guidelines exist for assessment of aetiology of intellectual disability in adults with intellectual disability by adult physicians, although robust guidelines exist for paediatric populations. It was speculated that the paediatric guidelines would also be suitable for adults. In rural/regional setting with limited clinical genetics, to perform a quality assurance evaluation on genetics assessment of aetiology of developmental disability in adults attending a dedicated healthcare clinic for adults with intellectual disability, compared results with paediatric standards, speculates if these seem appropriate for adults and speculates on a role for clinical genetics services. Retrospective chart audit of eligible patients looking at genetic clinical assessment, tests selected (molecular karyotype, G banding, metabolics), and yields of positive results. The results were compared with the recommended paediatric guidelines. Of 117 eligible adult patients, ideal genetic history was incomplete for 40% of patients without Down syndrome because of physician cause and lack of information. The number of abnormal genetic results increased from 46% to 66%, mainly from the molecular karyotype, though not all may have been clinically relevant. The improved yield from this test was similar to that in paediatric studies. Use of G banding and metabolic testing could be refined. Improvement can be made in clinical genetic assessment, but results generally support use of molecular karyotyping as first tier testing of cause of unknown intellectual disability in adults, as in the case for paediatric populations. The study highlights a necessary complementary role for clinical geneticists to interpret abnormal results. © 2016 Royal Australasian College of Physicians.

A Hispanic mother's beliefs about stuttering aetiology: A systemic functional linguistic analysis.

Science.gov (United States)

Medina, Angela M

2018-06-01

The aim of this study was to identify the linguistic resources a Hispanic mother used to convey her beliefs about the aetiology of her adult son's stuttering. A qualitative research paradigm was adopted for data collection and analysis. An Ecuadorian mother and her adult son who stutters recorded a conversation in Spanish about the son's stuttering. Tools derived from systemic functional linguistic (SFL) theory were used to analyse conversation transcripts and to describe the word choices and sentence structures the mother used to talk about her son's stuttering. The mother deflected community-assigned blame for causing her son's stuttering by configuring her 'strong' temperament as a separate, uncontrollable entity. She structured the pervasiveness of stigma, lack of resources and misinformation within the community as causes for her inability to identify and seek help for her son's stuttering, which also served as a means for deflecting blame. SFL-based analyses were appropriate tools for the investigation of how a Hispanic mother construes her views, attitudes and experiences relative to her son's stuttering. Clinical implications of findings regarding parent education and the utility of SFL-based tools in the speech-language therapy setting are discussed.

Growth hormone abuse and bodybuilding as aetiological factors in the development of bilateral internal laryngocoeles. A case report.

Science.gov (United States)

Moor, James W; Khan, M Iqbal J

2005-07-01

A 36-year-old man presented with hoarseness and stridor. He was an elite professional bodybuilder and admitted to having abusing anabolic steroids and growth hormone in the recent past. A CT scan showed bilateral laryngocoeles. The patient was initially managed with intravenous corticosteroids and broad-spectrum antibiotics, and the stridor resolved sufficiently to permit discharge from the hospital. He proceeded to undergo endoscopic marsupialisation of his laryngocoeles and to date has made a full recovery. This is the first reported case where anabolic steroid and growth hormone abuse combined with an elite bodybuilder's exercise regime has been implicated in the aetiology of bilateral laryngocoeles.

Microcracking in composite laminates under thermal and mechanical loading. Thesis

Science.gov (United States)

Maddocks, Jason R.

1995-01-01

Composites used in space structures are exposed to both extremes in temperature and applied mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. The goal of the present investigation is to develop a predictive methodology to quantify microcracking in general composite laminates under both thermal and mechanical loading. This objective is successfully met through a combination of analytical modeling and experimental investigation. In the analysis, the stress and displacement distributions in the vicinity of a crack are determined using a shear lag model. These are incorporated into an energy based cracking criterion to determine the favorability of crack formation. A progressive damage algorithm allows the inclusion of material softening effects and temperature-dependent material properties. The analysis is implemented by a computer code which gives predicted crack density and degraded laminate properties as functions of any thermomechanical load history. Extensive experimentation provides verification of the analysis. AS4/3501-6 graphite/epoxy laminates are manufactured with three different layups to investigate ply thickness and orientation effects. Thermal specimens are cooled to progressively lower temperatures down to -184 C. After conditioning the specimens to each temperature, cracks are counted on their edges using optical microscopy and in their interiors by sanding to incremental depths. Tensile coupons are loaded monotonically to progressively higher loads until failure. Cracks are counted on the coupon edges after each loading. A data fit to all available results provides input parameters for the analysis and shows them to be material properties, independent of geometry and loading. Correlation between experiment and analysis is generally very good under both thermal and mechanical loading, showing the methodology to be a powerful, unified tool. Delayed crack initiation observed in a few cases is attributed to a

An agent-based simulation of power generation company behavior in electricity markets under different market-clearing mechanisms

International Nuclear Information System (INIS)

Aliabadi, Danial Esmaeili; Kaya, Murat; Şahin, Güvenç

2017-01-01

Deregulated electricity markets are expected to provide affordable electricity for consumers through promoting competition. Yet, the results do not always fulfill the expectations. The regulator's market-clearing mechanism is a strategic choice that may affect the level of competition in the market. We conceive of the market-clearing mechanism as composed of two components: pricing rules and rationing policies. We investigate the strategic behavior of power generation companies under different market-clearing mechanisms using an agent-based simulation model which integrates a game-theoretical understanding of the auction mechanism in the electricity market and generation companies' learning mechanism. Results of our simulation experiments are presented using various case studies representing different market settings. The market in simulations is observed to converge to a Nash equilibrium of the stage game or to a similar state under most parameter combinations. Compared to pay-as-bid pricing, bid prices are closer to marginal costs on average under uniform pricing while GenCos' total profit is also higher. The random rationing policy of the ISO turns out to be more successful in achieving lower bid prices and lower GenCo profits. In minimizing GenCos' total profit, a combination of pay-as-bid pricing rule and random rationing policy is observed to be the most promising. - Highlights: • An agent-based simulation of generation company behavior in electricity markets is developed. • Learning dynamics of companies is modeled with an extended Q-learning algorithm. • Different market clearing mechanisms of the regulator are compared. • Convergence to Nash equilibria is analyzed under different cases. • The level of competition in the market is studied.

Comparison of radiological findings and microbial aetiology of childhood pneumonia

International Nuclear Information System (INIS)

Korppi, M.; Kiekara, O.; Kosma, T.H.; Soimakallio, S.

1993-01-01

61 children were treated in hospital from 1981 to 1982 because of both radiologically and microbiologically verified viral or bacterial pneumonia. The chest radiographs were interpreted by two radiologists, not familiar with the clinical data, on two occasions three years apart, and only those patients with a definite alveolar or interstitial pneumonia at both evaluations were included in the present analysis. In addition, all patients had viral, mixed viral-bacterial or bacterial infections diagnosed by viral or bacterial antibody or antigen assays. Viral infection alone was seen in 7, mixed viral-bacterial infection in 8 and bacterial infection alone in 12 of the 27 patients with alveolar pneumonia. The respective figures were 13, 13 and 8 for the 34 patients with interstitial pneumonia. C-reactive protein concentration was greater than 40 mg/l in 15 of the patients with alveolar and in 11 of the patients with interstitial pneumonia. Thus 74% of the patients with alveolar and 62% with interstitial pneumonia had bacterial infection, either alone or as a mixed viral-bacterial infection. The results suggest that the presence of an alveolar infiltrate in a chest radiograph is a specific but insensitive indicator of bacterial pneumonia. It is concluded that patients with alveolar pneumonia should be treated with antibiotics. In patients with interstitial pneumonia, however, both viral and bacterial aetiology are possible. In those, the decision concerning antibiotic treatment should be based on clinical and laboratory findings. 21 refs., 4 tabs

Vulvovaginitis: clinical features, aetiology, and microbiology of the genital tract

Science.gov (United States)

Jaquiery, A; Stylianopoulos, A; Hogg, G; Grover, S

1999-01-01

AIM—To clarify the contribution of clinical and environmental factors and infection to the aetiology of vulvovaginitis in premenarchal girls, and to determine clinical indicators of an infectious cause.
DESIGN—It was necessary first to define normal vaginal flora. Cases were 50 premenarchal girls > 2 years old with symptoms of vulvovaginitis; 50 controls were recruited from girls in the same age group undergoing minor or elective surgery.
RESULTS—Interview questionnaire showed no difference between cases and controls in regards to hygiene practices, exposure to specific irritants, or history of possible sexual abuse. Normal vaginal flora was similar to that described in previous studies, with the exception of organisms likely to be associated with sexual activity. 80% of cases had no evidence of an infectious cause. In the 10 cases in whom an infectious cause was found, there was significantly more visible discharge and distinct redness of the genital area on examination compared with other cases.
CONCLUSIONS— The findings suggest that vulvovaginitis in this age group is not usually infectious or necessarily related to poor hygiene, specific irritants or sexual abuse, although any of these can present with genital irritation. The possibility of sexual abuse should always be considered when a child presents with genital symptoms, but our data indicate it is not a common contributing factor. Infection is generally associated with vaginal discharge and moderate or severe inflammation.

 PMID:10373139

Failure mechanisms of aluminium foams under compressive loads

Directory of Open Access Journals (Sweden)

Sáenz, E.

2000-08-01

Full Text Available The purpose of this paper is the investigation of the major failure mechanisms of aluminium foams, which were obtained by powder metallurgy route, under compressive loads. The study was focused on two commonly aluminium alloys AlMg1Si or A 6061 and AlSi12. Due to the fact that the failure mechanisms strongly depend on the density and the macrostructural properties of the material, the mechanical properties always have to be correlated to the structural properties. Therefore, macrostructural investigations were used as a basis to establish the correlation between structural and mechanical properties. This was done with a commercially available image analysis system. The average cell size, the cell size distribution and the cell density (number of cells/area were obtained. In order to evaluate the influence of foaming direction on the cell morphology, some cross sections parallel to the foaming direction were prepared. For the characterization of the mechanical compression properties the compressive or upper yield strength (UYS, the densification strain (eD, the energy absorption (Ea and the efficiency (Eff were obtained. Furthermore, the failure behavior of the samples was in-situ observed with a digital video camera and continuously recorded during the test.

El objetivo de este estudio es investigar los principales mecanismos de fallo de espumas de aluminio sometidas a cargas de compresión. Las espumas metálicas fueron obtenidas mediante el proceso pulvimetalúrgico, utilizándose como materia prima dos aleaciones comerciales AlMg1Si o A 6061 y AlSi12. Debido a que los mecanismos de fallo en este tipo de materiales depende fuertemente de la densidad y las características macroestructurales del material, en este estudio se busca correlacionar las propiedades mecánicas con estas características. La macroestructura se caracterizó mediante análisis de imagen. El tamaño de celda promedio, la distribución de tamaño y la densidad de

The Immunomodulatory Effects of Macrolides—A Systematic Review of the Underlying Mechanisms

Directory of Open Access Journals (Sweden)

Petra Zimmermann

2018-03-01

Full Text Available BackgroundThe mechanisms underlying the non-antimicrobial immunomodulatory properties of macrolides are not well understood.ObjectivesTo systematically review the evidence for the immunomodulatory properties of macrolides in humans and to describe the underlying mechanism and extent of their influence on the innate and adaptive immune system.MethodsA systematic literature search was done in MEDLINE using the OVID interface from 1946 to December 2016 according to the preferred reporting items for systematic reviews and meta-analysis (PRISMA. Original articles investigating the influence of four macrolides (azithromycin, clarithromycin, erythromycin, and roxithromycin on immunological markers in humans were included.ResultsWe identified 22 randomized, controlled trials, 16 prospective cohort studies, and 8 case–control studies investigating 47 different immunological markers (186 measurements in 1,834 participants. The most frequently reported outcomes were a decrease in the number of neutrophils, and the concentrations of neutrophil elastase, interleukin (IL-8, IL-6, IL-1beta, tumor necrosis factor (TNF-alpha, eosinophilic cationic protein, and matrix metalloproteinase 9. Inhibition of neutrophil function was reported more frequently than eosinophil function. A decrease in T helper (Th 2 cells cytokines (IL-4, IL-5, IL-6 was reported more frequently than a decrease in Th1 cytokines (IL-2, INF-gamma.ConclusionMacrolides influence a broad range of immunological mechanisms resulting in immunomodulatory effects. To optimize the treatment of chronic inflammatory diseases by macrolides, further studies are necessary, particularly comparing different macrolides and dose effect relationships.

Effects of delaying transplanting on agronomic traits and grain yield of rice under mechanical transplantation pattern.

Directory of Open Access Journals (Sweden)

Qihua Liu

Full Text Available A delay in the mechanical transplantation (MT of rice seedlings frequently occurs in Huanghuai wheat-rice rotation cropping districts of China, due to the late harvest of wheat, the poor weather conditions and the insufficiency of transplanters, missing the optimum transplanting time and causing seedlings to age. To identify how delaying transplanting rice affects the agronomic characteristics including the growth duration, photosynthetic productivity and dry matter remobilization efficiency and the grain yield under mechanical transplanting pattern, an experiment with a split-plot design was conducted over two consecutive years. The main plot includes two types of cultivation: mechanical transplanting and artificial transplanting (AT. The subplot comprises four japonica rice cultivars. The results indicate that the rice jointing, booting, heading and maturity stages were postponed under MT when using AT as a control. The tiller occurrence number, dry matter weight per tiller, accumulative dry matter for the population, leaf area index, crop growth rate, photosynthetic potential, and dry matter remobilization efficiency of the leaf under MT significantly decreased compared to those under AT. In contrast, the reduction rate of the leaf area during the heading-maturity stage was markedly enhanced under MT. The numbers of effective panicles and filled grains per panicle and the grain yield significantly decreased under MT. A significant correlation was observed between the dry matter production, remobilization and distribution characteristics and the grain yield. We infer that, as with rice from old seedlings, the decrease in the tiller occurrence, the photosynthetic productivity and the assimilate remobilization efficiency may be important agronomic traits that are responsible for the reduced grain yield under MT.

Research on energy conversion mechanism of a screw centrifugal pump under the water

International Nuclear Information System (INIS)

Quan, H; Li, R N; Han, W; Cheng, X R; Shen, Z J; Su, Q M

2013-01-01

In order to research screw centrifugal pump impeller power capability and energy conversion mechanism, we used Navier-Stokes equation and standard k-ε equation turbulence model on the basis of the Euler equations to carry out screw centrifugal pump internal flow numerical simulation. This was explored by simulating specific design conditions; the medium is water, variation of speed and pressure of flow filed under the action of the impeller, and the screw centrifugal impeller shroud line and wheel line segment take monitoring sites. The monitoring points are between dynamic head and static head change to analyze the energy conversion capability along the impeller corners of screw centrifugal pump. The results show that the energy of fluid of the screw centrifugal pump is provided by spiral segment, the spiral segment in front of the impeller has played a multi-level role, it has significant reference value to research the energy conversion mechanism of screw centrifugal pump under solid-liquid two phase

CISM course on mechanical behaviour of soils under environmentally induced cyclic loads

CERN Document Server

Wood, David; Mechanical Behaviour of Soils Under Environmentally Induced Cyclic Loads

2012-01-01

The book gives a comprehensive description of the mechanical response of soils (granular and cohesive materials) under cyclic loading. It provides the geotechnical engineer with the theoretical and analytical tools necessary for the evaluation of settlements developng with time under cyclic, einvironmentally idncued loads (such as wave motion, wind actions, water table level variation) and their consequences for the serviceability and durability of structures such as the shallow or deep foundations used in offshore engineering, caisson beakwaters, ballast and airport pavements and also to interpret monitoring data, obtained from both natural and artificial slopes and earth embankments, for the purposes of risk assessment and mitigation.

Biological mechanisms underlying the role of physical fitness in health and resilience

OpenAIRE

Silverman, Marni N.; Deuster, Patricia A.

2014-01-01

Physical fitness, achieved through regular exercise and/or spontaneous physical activity, confers resilience by inducing positive psychological and physiological benefits, blunting stress reactivity, protecting against potentially adverse behavioural and metabolic consequences of stressful events and preventing many chronic diseases. In this review, we discuss the biological mechanisms underlying the beneficial effects of physical fitness on mental and physical health. Physical fitness appear...

STUDY OF THE CLINICAL PROFILE AND AETIOLOGY OF VARIOUS DISORDERS OF SEX DEVELOPMENT PRESENTING TO ENDOCRINE OPD OF A TERTIARY CARE HOSPITAL

Directory of Open Access Journals (Sweden)

Ipsita Mishra

2017-10-01

Full Text Available BACKGROUND Disorders of Sex Development (DSD, formerly described as intersex conditions, are a conglomerate of rare disorders defined as discrepancy of chromosomal, gonadal or anatomic sex. There are limited data on the incidence of DSD with an overall incidence of 1:5,500, but varies with population. Congenital adrenal hyperplasia and mixed gonadal dysgenesis are the most common causes of ambiguous genitalia constituting approximately 50% of all cases presenting with genital ambiguity at birth. The aim of the study is to study the clinical profile and aetiology, mean age of presentation of common aetiologies, initial sex of rearing based on genital ambiguity and correctness of sex of rearing since birth as compared to genetic karyotype after diagnosis of patients of various disorders of sex development presenting to endocrine OPD of a tertiary care hospital. MATERIALS AND METHODS We assessed the records of patients who were evaluated for hypogonadism and genital ambiguity between March 2014 to June 2017 in our endocrine department. The patients were classified on the basis of clinical features, hormonal investigations, imaging studies, karyotype and laparoscopy/biopsy studies as indicated. Design- Cross-sectional study. RESULTS Distribution of DSD by category were 46, XY DSD (41.6%; 46, XX DSD (27.3%; SCD DSD (30.9%. Distribution of DSD by subtypes were 46, XY DSD; -5α reductase (37.1%; IHH (20.1%; Kallmann syndrome (14.28%; bilateral anorchia (11%; PAIS (8.5%; CAIS (2.8%; CAH (2.8%; 46, XX DSD-CAH (34.1%; IHH (21.7%; 46, XX OTD (13%; ACC (8.6%; classic CAH (4.3%; SCD DSD-KFS (53.8%; TS (38.4% and MGD (7.69%. Mean age of presentation of DSD; 5α reductase (7.5 yrs., PAIS (14.33 yrs., CAH (9.3 yrs., KFS (25 yrs. and TS (17 yrs.. CONCLUSION 46 XY DSD comprises 41.6% of cases of which 5α reductase deficiency is the most common aetiology. CAH was the main subtype of 46, XX DSD. KFS was the main subtype of SCD DSD. DSD pose a serious challenge not

Possible Mechanisms Underlying the Therapeutic Effects of Transcranial Magnetic Stimulation

Science.gov (United States)

Chervyakov, Alexander V.; Chernyavsky, Andrey Yu.; Sinitsyn, Dmitry O.; Piradov, Michael A.

2015-01-01

Transcranial magnetic stimulation (TMS) is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS) has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson’s disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation and long-term depression. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells, and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals). It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols. PMID:26136672

Mechanical measurement of hydrogen bonded host-guest systems under non-equilibrium, near-physiological conditions.

Science.gov (United States)

Naranjo, Teresa; Cerrón, Fernando; Nieto-Ortega, Belén; Latorre, Alfonso; Somoza, Álvaro; Ibarra, Borja; Pérez, Emilio M

2017-09-01

Decades after the birth of supramolecular chemistry, there are many techniques to measure noncovalent interactions, such as hydrogen bonding, under equilibrium conditions. As ensembles of molecules rapidly lose coherence, we cannot extrapolate bulk data to single-molecule events under non-equilibrium conditions, more relevant to the dynamics of biological systems. We present a new method that exploits the high force resolution of optical tweezers to measure at the single molecule level the mechanical strength of a hydrogen bonded host-guest pair out of equilibrium and under near-physiological conditions. We utilize a DNA reporter to unambiguously isolate single binding events. The Hamilton receptor-cyanuric acid host-guest system is used as a test bed. The force required to dissociate the host-guest system is ∼17 pN and increases with the pulling rate as expected for a system under non-equilibrium conditions. Blocking one of the hydrogen bonding sites results in a significant decrease of the force-to-break by 1-2 pN, pointing out the ability of the method to resolve subtle changes in the mechanical strength of the binding due to the individual H-bonding components. We believe the method will prove to be a versatile tool to address important questions in supramolecular chemistry.

Neuro-cognitive mechanisms underlying the emotional modulation of word reading

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

A novel neural model for emotional modulation of word reading is proposed. This model has four principal hypotheses: the dominant activation region hypothesis, the emotional modulation hypothesis, the attentional level hypothesis, and the interaction hypothesis. Four lines of research were reviewed to provide evidence for these hypotheses: (1) neuro-cognitive studies on the mechanisms of word reading (i.e., neural networks for reading); (2) studies on the influence of words' emotional valence on word reading; (3) studies of the effect of attention on word reading; and (4) studies on emotional modulation of word reading under different attentional levels.

Jung's views on causes and treatments of schizophrenia in light of current trends in cognitive neuroscience and psychotherapy research I. Aetiology and phenomenology.

Science.gov (United States)

Silverstein, Steven M

2014-02-01

Jung's writings on schizophrenia are almost completely ignored or forgotten today. The purpose of this paper, along with a follow-up article, is to review the primary themes found in Jung's writings on schizophrenia, and to assess the validity of his theories about the disorder in light of our current knowledge base in the fields of psychopathology, cognitive neuroscience and psychotherapy research. In this article, five themes related to the aetiology and phenomenology of schizophrenia from Jung's writings are discussed:1) abaissement du niveau mental; 2) the complex; 3) mandala imagery; 4) constellation of archetypes and 5) psychological versus toxic aetiology. Reviews of the above areas suggest three conclusions. First, in many ways, Jung's ideas on schizophrenia anticipated much current thinking and data about the disorder. Second, with the recent (re)convergence of psychological and biological approaches to understanding and treating schizophrenia, the pioneering ideas of Jung regarding the importance of both factors and their interaction remain a useful and rich, but still underutilized resource. Finally, a more concerted effort to understand and evaluate the validity of Jung's concepts in terms of evidence from neuroscience could lead both to important advances in analytical psychology and to developments in therapeutic approaches that would extend beyond the treatment of schizophrenia. © 2014, The Society of Analytical Psychology.

Investigation of deterioration mechanism of electrical ceramic insulating materials under high temperature

International Nuclear Information System (INIS)

Mizutani, Yoshinobu; Ito, Tetsuo; Okamoto, Tatsuki; Kumazawa, Ryoji; Aizawa, Rie; Moriyama, Hideshige

2000-01-01

It is thought that ceramic insulator can be applied to electric power equipments that are under high temperature not to be able use organic materials. Our research has suggested components of mica-alumina combined insulation. As the results of and carried out temperature accelerating test, combined insulation life is expected long term over 40 years at over 500-Celsius degrees. However to construct high reliable insulating system, it is clarified deterioration mechanism on combined insulation and evaluates life of that. Therefore we carried out metal behavior test and voltage aging test using mica-sheet and alumina-cloth that are components of combined insulation under high temperature in nitrogen gas atmosphere. It is cleared two metal behavior mechanisms: One is that the opening of insulator are filled up with copper that is oxidized, the other is the metal diffuses in alumina-cloth through surface. And distance of metal behavior is able to be estimated at modulate temperature and in modulate time. It is also cleared that alumina-cloth is deteriorated by metal behavior into alumina-cloth. These results indicate that combined insulation is deteriorated from electrode side by metal behavior and is finally broken down through alumina-cloth. (author)

Mechanical behavior of glass/epoxy composite laminate with varying amount of MWCNTs under different loadings

Science.gov (United States)

Singh, K. K.; Rawat, Prashant

2018-05-01

This paper investigates the mechanical response of three phased (glass/MWCNTs/epoxy) composite laminate under three different loadings. Flexural strength, short beam strength and low-velocity impact (LVI) testing are performed to find an optimum doping percentage value for maximum enhancement in mechanical properties. In this work, MWCNTs were used as secondary reinforcement for three-phased composite plate. MWCNT doping was done in a range of 0–4 wt% of the thermosetting matrix system. Symmetrical design eight layered glass/epoxy laminate with zero bending extension coupling laminate was fabricated using a hybrid method i.e. hand lay-up technique followed by vacuum bagging method. Ranging analysis of MWCNT mixing highlighted the enhancement in flexural, short beam strength and improvement in damage tolerance under LVI loading. While at higher doping wt%, agglomeration of MWCNTs are observed. Results of mechanical testing proposed an optimized doping value for maximum strength and damage resistance of the laminate.

Mechanical characteristics under monotonic and cyclic simple shear of spark plasma sintered ultrafine-grained nickel

International Nuclear Information System (INIS)

Dirras, G.; Bouvier, S.; Gubicza, J.; Hasni, B.; Szilagyi, T.

2009-01-01

The present work focuses on understanding the mechanical behavior of bulk ultrafine-grained nickel specimens processed by spark plasma sintering of high purity nickel nanopowder and subsequently deformed under large amplitude monotonic simple shear tests and strain-controlled cyclic simple shear tests at room temperature. During cyclic tests, the samples were deformed up to an accumulated von Mises strain of about ε VM = 0.75 (the flow stress was in the 650-700 MPa range), which is extremely high in comparison with the low tensile/compression ductility of this class of materials at quasi-static conditions. The underlying physical mechanisms were investigated by electron microscopy and X-ray diffraction profile analysis. Lattice dislocation-based plasticity leading to cell formation and dislocation interactions with twin boundaries contributed to the work-hardening of these materials. The large amount of plastic strain that has been reached during the shear tests highlights intrinsic mechanical characteristics of the ultrafine-grained nickel studied here.

Mechanical characteristics under monotonic and cyclic simple shear of spark plasma sintered ultrafine-grained nickel

Energy Technology Data Exchange (ETDEWEB)

Dirras, G., E-mail: dirras@univ-paris13.fr [LPMTM - CNRS, Institut Galilee, Universite Paris 13, 99 Avenue J.B. Clement, 93430 Villetaneuse (France); Bouvier, S. [LPMTM - CNRS, Institut Galilee, Universite Paris 13, 99 Avenue J.B. Clement, 93430 Villetaneuse (France); Gubicza, J. [Department of Materials Physics, Eoetvoes Lorand University, P.O.B. 32, Budapest H-1518 (Hungary); Hasni, B. [LPMTM - CNRS, Institut Galilee, Universite Paris 13, 99 Avenue J.B. Clement, 93430 Villetaneuse (France); Szilagyi, T. [Department of Materials Physics, Eoetvoes Lorand University, P.O.B. 32, Budapest H-1518 (Hungary)

2009-11-25

The present work focuses on understanding the mechanical behavior of bulk ultrafine-grained nickel specimens processed by spark plasma sintering of high purity nickel nanopowder and subsequently deformed under large amplitude monotonic simple shear tests and strain-controlled cyclic simple shear tests at room temperature. During cyclic tests, the samples were deformed up to an accumulated von Mises strain of about {epsilon}{sub VM} = 0.75 (the flow stress was in the 650-700 MPa range), which is extremely high in comparison with the low tensile/compression ductility of this class of materials at quasi-static conditions. The underlying physical mechanisms were investigated by electron microscopy and X-ray diffraction profile analysis. Lattice dislocation-based plasticity leading to cell formation and dislocation interactions with twin boundaries contributed to the work-hardening of these materials. The large amount of plastic strain that has been reached during the shear tests highlights intrinsic mechanical characteristics of the ultrafine-grained nickel studied here.

Intercomparison of chemical mechanisms for air quality policy formulation and assessment under North American conditions.

Science.gov (United States)

Derwent, Richard

2017-07-01

The intercomparison of seven chemical mechanisms for their suitability for air quality policy formulation and assessment is described. Box modeling techniques were employed using 44 sets of background environmental conditions covering North America to constrain the chemical development of the longer lived species. The selected mechanisms were modified to enable an unbiased assessment of the adequacy of the parameterizations of photochemical ozone production from volatile organic compound (VOC) oxidation in the presence of NO x . Photochemical ozone production rates responded differently to 30% NO x and VOC reductions with the different mechanisms, despite the striking similarities between the base-case ozone production rates. The 30% reductions in NO x and VOCs also produced changes in OH. The responses in OH to 30% reductions in NO x and VOCs appeared to be more sensitive to mechanism choice, compared with the responses in the photochemical ozone production rates. Although 30% NO x reductions generally led to decreases in OH, 30% reductions in VOCs led to increases in OH, irrespective of mechanism choice and background environmental conditions. The different mechanisms therefore gave different OH responses to NO x and VOC reductions and so would give different responses in terms of changes in the fate and behavior of air toxics, acidification and eutrophication, and fine particle formation compared with others, in response to ozone control strategies. Policymakers need to understand that there are likely to be inherent differences in the responses to ozone control strategies between different mechanisms, depending on background environmental conditions and the extents of NO x and VOC reductions under consideration. The purpose of this paper is to compare predicted ozone responses to NO x and VOC reductions with seven chemical mechanisms under North American conditions. The good agreement found between the tested mechanisms should provide some support for their

Experimental Investigation on Shock Mechanical Properties of Red Sandstone under Preloaded 3D Static Stresses

Directory of Open Access Journals (Sweden)

Niu Yong

2015-11-01

Full Text Available Triaxial impact mechanical performance experiment was performed to study the mechanical properties of red sandstone subjected to three-dimensional (3D coupled static and dynamic loads, i.e., three confining pressures (0, 5, and 10 MPa and three axial pressures (11, 27, and 43 MPa. A modified 3D split Hopkinson pressure bar testing system was used. The change trend in the deformation of red sandstone and the strength and failure modes under axial pressures and confining pressures were analyzed. Results show that, when the confining pressure is constant, the compressive strength, secant modulus, and energy absorbed per unit volume of red sandstone initially increases and subsequently decreases, whereas the average strain rate exhibits an opposite trend. When the axial pressure is constant, both the compressive strength and secant modulus of red sandstone are enhanced, but the average strain rate is decreased with increasing confining pressure. The energy absorbed per unit volume is initially increased and subsequently decreased as the confining pressure increases. Red sandstone exhibits a cone-shaped compression–shear failure mode under the 3D coupled static and dynamic loads. The conclusions serve as theoretical basis on the mechanical properties of deep medium-strength rock under a high ground stress and external load disturbance condition

Interactivity effects in social media marketing on brand engagement: an investigation of underlying mechanisms

NARCIS (Netherlands)

Antheunis, M.L.; van Noort, G.; Eisend, M.; Langner, T.

2011-01-01

Although, SNS advertising spending increases, research on SNS campaigning is still underexposed. First, this study aims to investigate the effect of SNS campaign interactivity on the receivers brand engagement, taking four underlying mechanisms into account (brand identification, campaign

Hardening and softening mechanisms of pearlitic steel wire under torsion

International Nuclear Information System (INIS)

Zhao, Tian-Zhang; Zhang, Shi-Hong; Zhang, Guang-Liang; Song, Hong-Wu; Cheng, Ming

2014-01-01

Highlights: • Mechanical behavior of pearlitic steel wire is studied using torsion. • Work hardening results from refinement lamellar pearlitic structure. • Softening results from recovery, shear bands and lamellar fragmentations. • A microstructure based analytical flow stress model is established. - Abstract: The mechanical behaviors and microstructure evolution of pearlitic steel wires under monotonic shear deformation have been investigated by a torsion test and a number of electron microscopy techniques including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with an aim to reveal the softening and hardening mechanisms of a randomly oriented pearlitic structure during a monotonic stain path. Significantly different from the remarkable strain hardening in cold wire drawing, the strain hardening rate during torsion drops to zero quickly after a short hardening stage. The microstructure observations indicate that the inter-lamellar spacing (ILS) decreases and the dislocations accumulate with strain, which leads to hardening of the material. Meanwhile, when the strain is larger than 0.154, the enhancement of dynamic recovery, shear bands (SBs) and cementite fragmentations results in the softening and balances the strain hardening. A microstructure based analytical flow stress model with considering the influence of ILS on the mean free path of dislocations and the softening caused by SBs and cementite fragmentations, has been established and the predicted flow shear curve meets well with the measured curve in the torsion test

Ultrastructural changes of cell walls under intense mechanical treatment of selective plant raw material

International Nuclear Information System (INIS)

Bychkov, Aleksey L.; Ryabchikova, E.I.; Korolev, K.G.; Lomovsky, O.I.

2012-01-01

Structural changes of cell walls under intense mechanical treatment of corn straw and oil-palm fibers were studied by electron and light microscopy. Differences in the character of destruction of plant biomass were revealed, and the dependence of destruction mechanisms on the structure of cell walls and lignin content was demonstrated. We suggest that the high reactivity of the particles of corn straw (about 18% of lignin) after intense mechanical treatment is related to disordering of cell walls and an increase of the surface area, while in the case of oil palm (10% of lignin) the major contribution into an increase in the reactivity is made by an increase of surface area. -- Highlights: ► Structure of cell walls determines the processes of plant materials' destruction. ► Ultrastructure of highly lignified materials strongly disordering by mechanical action. ► Ultrastructure of low-lignified materials is not disordering by mechanical action.

Survey on the importance of mange in the aetiology of skin lesions in goats in Peninsular Malaysia.

Science.gov (United States)

Dorny, P; Van Wyngaarden, T; Vercruysse, J; Symoens, C; Jalia, A

1994-05-01

A survey on mange mite infestations in the aetiology of skin lesions in goats in Peninsular Malaysia is described. Skin lesions were observed in 25 (93%) of the 27 goat farms investigated. Mange mites were found in 22 (88%) of these goat herds. Chorioptes texanus was found in 20.7%, Psoroptes cuniculi in 19.3%, Sarcoptes scabiei in 18.6% and Demodex canis var. caprae in 0.4% of the samples, taken from the skin lesions. Thirteen cases of generalised manage were diagnosed, from which 9 were caused by S. scabiei, 2 by P. cuniculi and one by C. texanus. All other cases had more or less localised lesions. No significant differences could be found in incidence and distribution of skin lesions between age classes.

Molecular mechanisms underlying formation of long-term reward memories and extinction memories in the honeybee (Apis mellifera)

Science.gov (United States)

2014-01-01

The honeybee (Apis mellifera) has long served as an invertebrate model organism for reward learning and memory research. Its capacity for learning and memory formation is rooted in the ecological need to efficiently collect nectar and pollen during summer to ensure survival of the hive during winter. Foraging bees learn to associate a flower's characteristic features with a reward in a way that resembles olfactory appetitive classical conditioning, a learning paradigm that is used to study mechanisms underlying learning and memory formation in the honeybee. Due to a plethora of studies on appetitive classical conditioning and phenomena related to it, the honeybee is one of the best characterized invertebrate model organisms from a learning psychological point of view. Moreover, classical conditioning and associated behavioral phenomena are surprisingly similar in honeybees and vertebrates, suggesting a convergence of underlying neuronal processes, including the molecular mechanisms that contribute to them. Here I review current thinking on the molecular mechanisms underlying long-term memory (LTM) formation in honeybees following classical conditioning and extinction, demonstrating that an in-depth analysis of the molecular mechanisms of classical conditioning in honeybees might add to our understanding of associative learning in honeybees and vertebrates. PMID:25225299

Using Drosophila to discover mechanisms underlying type 2 diabetes

Directory of Open Access Journals (Sweden)

Ronald W. Alfa

2016-04-01

Full Text Available Mechanisms of glucose homeostasis are remarkably well conserved between the fruit fly Drosophila melanogaster and mammals. From the initial characterization of insulin signaling in the fly came the identification of downstream metabolic pathways for nutrient storage and utilization. Defects in these pathways lead to phenotypes that are analogous to diabetic states in mammals. These discoveries have stimulated interest in leveraging the fly to better understand the genetics of type 2 diabetes mellitus in humans. Type 2 diabetes results from insulin insufficiency in the context of ongoing insulin resistance. Although genetic susceptibility is thought to govern the propensity of individuals to develop type 2 diabetes mellitus under appropriate environmental conditions, many of the human genes associated with the disease in genome-wide association studies have not been functionally studied. Recent advances in the phenotyping of metabolic defects have positioned Drosophila as an excellent model for the functional characterization of large numbers of genes associated with type 2 diabetes mellitus. Here, we examine results from studies modeling metabolic disease in the fruit fly and compare findings to proposed mechanisms for diabetic phenotypes in mammals. We provide a systematic framework for assessing the contribution of gene candidates to insulin-secretion or insulin-resistance pathways relevant to diabetes pathogenesis.

The underlying mechanism of action for various medicinal properties of Piper betle (betel).

Science.gov (United States)

Haslan, H; Suhaimi, F H; Thent, Zar Chi; Das, S

2015-01-01

Piper betle (betel) plant belongs to the Piperaceae family. Piper. betle is widely known for its potent medicinal properties. Various active compounds are present in Piper. betle such as allylpyrocatechol, hydroxychavicol, piperbetol, ethylpiperbetol, piperol A, piperol B, chavibetol, and alkaloids which account for these beneficial medicinal properties. In the present narrative review, we looked into the various active compounds present in the Piper betle and attempted to understand their underlying mechanism of action. Proper understanding of the molecular biology involving the mechanism of action may help in better drug formulation and provide better therapeutic actions in the field of alternative and complementary medicine.

Mechanical Modeling of a WIPP Drum Under Pressure

Energy Technology Data Exchange (ETDEWEB)

Smith, Jeffrey A. [Sandia National Laboratories, Albuquerque, NM (United States)

2014-11-25

Mechanical modeling was undertaken to support the Waste Isolation Pilot Plant (WIPP) technical assessment team (TAT) investigating the February 14th 2014 event where there was a radiological release at the WIPP. The initial goal of the modeling was to examine if a mechanical model could inform the team about the event. The intention was to have a model that could test scenarios with respect to the rate of pressurization. It was expected that the deformation and failure (inability of the drum to contain any pressure) would vary according to the pressurization rate. As the work progressed there was also interest in using the mechanical analysis of the drum to investigate what would happen if a drum pressurized when it was located under a standard waste package. Specifically, would the deformation be detectable from camera views within the room. A finite element model of a WIPP 55-gallon drum was developed that used all hex elements. Analyses were conducted using the explicit transient dynamics module of Sierra/SM to explore potential pressurization scenarios of the drum. Theses analysis show similar deformation patterns to documented pressurization tests of drums in the literature. The calculated failure pressures from previous tests documented in the literature vary from as little as 16 psi to 320 psi. In addition, previous testing documented in the literature shows drums bulging but not failing at pressures ranging from 69 to 138 psi. The analyses performed for this study found the drums failing at pressures ranging from 35 psi to 75 psi. When the drums are pressurized quickly (in 0.01 seconds) there is significant deformation to the lid. At lower pressurization rates the deformation of the lid is considerably less, yet the lids will still open from the pressure. The analyses demonstrate the influence of pressurization rate on deformation and opening pressure of the drums. Analyses conducted with a substantial mass on top of the closed drum demonstrate that the

Peripheral afferent mechanisms underlying acupuncture inhibition of cocaine behavioral effects in rats.

Directory of Open Access Journals (Sweden)

Seol Ah Kim

Full Text Available Administration of cocaine increases locomotor activity by enhancing dopamine transmission. To explore the peripheral mechanisms underlying acupuncture treatment for drug addiction, we developed a novel mechanical acupuncture instrument (MAI for objective mechanical stimulation. The aim of this study was to evaluate whether acupuncture inhibition of cocaine-induced locomotor activity is mediated through specific peripheral nerves, the afferents from superficial or deep tissues, or specific groups of nerve fibers. Mechanical stimulation of acupuncture point HT7 with MAI suppressed cocaine-induced locomotor activity in a stimulus time-dependent manner, which was blocked by severing the ulnar nerve or by local anesthesia. Suppression of cocaine-induced locomotor activity was elicited after HT7 stimulation at frequencies of either 50 (for Meissner corpuscles or 200 (for Pacinian corpuscles Hz and was not affected by block of C/Aδ-fibers in the ulnar nerve with resiniferatoxin, nor generated by direct stimulation of C/Aδ-fiber afferents with capsaicin. These findings suggest that HT7 inhibition of cocaine-induced locomotor activity is mediated by A-fiber activation of ulnar nerve that originates in superficial and deep tissue.

Mechanical characterisation of porcine rectus sheath under uniaxial and biaxial tension.

LENUS (Irish Health Repository)

Lyons, Mathew

2014-06-03

Incisional hernia development is a significant complication after laparoscopic abdominal surgery. Intra-abdominal pressure (IAP) is known to initiate the extrusion of intestines through the abdominal wall, but there is limited data on the mechanics of IAP generation and the structural properties of rectus sheath. This paper presents an explanation of the mechanics of IAP development, a study of the uniaxial and biaxial tensile properties of porcine rectus sheath, and a simple computational investigation of the tissue. Analysis using Laplace׳s law showed a circumferential stress in the abdominal wall of approx. 1.1MPa due to an IAP of 11kPa, commonly seen during coughing. Uniaxial and biaxial tensile tests were conducted on samples of porcine rectus sheath to characterise the stress-stretch responses of the tissue. Under uniaxial tension, fibre direction samples failed on average at a stress of 4.5MPa at a stretch of 1.07 while cross-fibre samples failed at a stress of 1.6MPa under a stretch of 1.29. Under equi-biaxial tension, failure occurred at 1.6MPa with the fibre direction stretching to only 1.02 while the cross-fibre direction stretched to 1.13. Uniaxial and biaxial stress-stretch plots are presented allowing detailed modelling of the tissue either in silico or in a surrogate material. An FeBio computational model of the tissue is presented using a combination of an Ogden and an exponential power law model to represent the matrix and fibres respectively. The structural properties of porcine rectus sheath have been characterised and add to the small set of human data in the literature with which it may be possible to develop methods to reduce the incidence of incisional hernia development.

Fracture Mechanisms of Zirconium Diboride Ultra-High Temperature Ceramics under Pulse Loading

Science.gov (United States)

Skripnyak, Vladimir V.; Bragov, Anatolii M.; Skripnyak, Vladimir A.; Lomunov, Andrei K.; Skripnyak, Evgeniya G.; Vaganova, Irina K.

2015-06-01

Mechanisms of failure in ultra-high temperature ceramics (UHTC) based on zirconium diboride under pulse loading were studied experimentally by the method of SHPB and theoretically using the multiscale simulation method. The obtained experimental and numerical data are evidence of the quasi-brittle fracture character of nanostructured zirconium diboride ceramics under compression and tension at high strain rates and the room temperatures. Damage of nanostructured porous zirconium diboride -based UHTC can be formed under stress pulse amplitude below the Hugoniot elastic limit. Fracture of nanostructured ultra-high temperature ceramics under pulse and shock-wave loadings is provided by fast processes of intercrystalline brittle fracture and relatively slow processes of quasi-brittle failure via growth and coalescence of microcracks. A decrease of the shear strength can be caused by nano-voids clusters in vicinity of triple junctions between ceramic matrix grains and ultrafine-grained ceramics. This research was supported by grants from ``The Tomsk State University Academic D.I. Mendeleev Fund Program'' and also N. I. Lobachevski State University of Nizhny Novgorod (Grant of post graduate mobility).

Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

Science.gov (United States)

Wang, Yanan; Qin, Qing-Hua

2010-03-01

The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.

Elucidating the molecular mechanisms underlying cellular response to biophysical cues using synthetic biology approaches

NARCIS (Netherlands)

Denning, Denise; Roos, Wouter H

2016-01-01

The use of synthetic surfaces and materials to influence and study cell behavior has vastly progressed our understanding of the underlying molecular mechanisms involved in cellular response to physicochemical and biophysical cues. Reconstituting cytoskeletal proteins and interfacing them with a

Cultural and religious components in Nigerian parents' perceptions of the aetiology of cleft lip and palate: implications for treatment and rehabilitation.

Science.gov (United States)

Olasoji, H O; Ugboko, V I; Arotiba, G T

2007-06-01

The present study was conducted to find out the perceptions of mothers from two Nigerian ethnic groups who had children with cleft lip and palate (CLP) about the aetiology of the defect. Mothers of 16 children with CLP from the Yoruba ethnic group who attended the maxillofacial clinic of the Obafemi Awolowo University teaching hospital in southern Nigeria and 20 children with CLP from the Hausa/Fulani ethnic group who attended the maxillofacial clinic of the University of Maiduguri teaching hospital in northeastern Nigeria were interviewed over an 8-month period. We used standardised interviews including questions with ethnographic components to allow us to collect information about traditional beliefs about clefts. Interviews were recorded on tape for later analysis. Thirteen of the 16 parents from the Yoruba group attributed the aetiology of CLP to supernatural forces (evil spirits and ancestral spirits), while 16 of the 20 Hausa/Fulani parents attributed it to the "will of God". Twelve of 16 Yoruba parents had consulted traditional healers for treatment before coming to the hospital. Various plants and animal products were used to treat clefts and 10 of the Yoruba parents were referred to the hospital for further treatment by the traditional healers. Cultural and religious factors seem to have an important role in the explanations, labels and treatment that followed the birth of a child with CLP in this environment. There is a need for greater collaboration and sharing of information between modern medical practitioners and traditional healers.

First-principles predictions of structural, mechanical and electronic properties of βTiNb under high pressure

Science.gov (United States)

Wang, Z. P.; Fang, Q. H.; Li, J.; Liu, B.

2018-04-01

Structural, mechanical and electronic properties of βTiNb alloy under high pressure have been investigated based on the density functional theory (DFT). The dependences of dimensionless volume ratio, elastic constants, bulk modulus, Young's modulus, shear modulus, ductile/brittle, anisotropy and Poisson's ratio on applied pressure are all calculated successfully. The results reveal that βTiNb alloy is mechanically stable under pressure below 23.45 GPa, and the pressure-induced phase transformation could occur beyond this critical value. Meanwhile, the applied pressure can effectively promote the mechanical properties of βTiNb alloy, including the resistances to volume change, elastic deformation and shear deformation, as well as the material ductility and metallicity. Furthermore, the calculated electronic structures testify that βTiNb alloy performs the metallicity and the higher pressure reduces the structural stability of unit cell.

Underlying mechanisms and the evolving influence of diet

DEFF Research Database (Denmark)

Larsen, Lesli Hingstrup

2012-01-01

Obesity is determined by both genetic and environmental factors. Since 2007, 52 genes have been associated with obesity and obesity-related measurements in genome-wide association studies (GWAS), among these the fat and obesity-associated gene (FTO). Despite the success in identifying genes predi...... and the microbiome that can be modified by diet, and by genotype, adding to the complexity of determining the contributors to obesity....... has been shown to attenuate the effect of FTO on obesity. Several studies have examined gene-diet interactions in relation to obesity, but only a few suggestive interactions have been identified. This is most probably due to small effect sizes of the interactions and thereby a demand for large samples...... to increased risk of developing obesity. Recently, the intestinal microbiome, the collected genome of the bacteria, also has been associated with obesity and with specific dietary profiles. The underlying mechanisms determining the susceptibility to obesity do not only include the genome but also the epigenome...

Optimal Contract Design for Cooperative Relay Incentive Mechanism under Moral Hazard

Directory of Open Access Journals (Sweden)

Nan Zhao

2015-01-01

Full Text Available Cooperative relay can effectively improve spectrum efficiency by exploiting the spatial diversity in the wireless networks. However, wireless nodes may acquire different network information with various users’ location and mobility, channels’ conditions, and other factors, which results in asymmetric information between the source and the relay nodes (RNs. In this paper, the relay incentive mechanism between relay nodes and the source is investigated under the asymmetric information. By modelling multiuser cooperative relay as a labour market, a contract model with moral hazard for relay incentive is proposed. To effectively incentivize the potential RNs to participate in cooperative relay, the optimization problems are formulated to maximize the source’s utility while meeting the feasible conditions under both symmetric and asymmetric information scenarios. Numerical simulation results demonstrate the effectiveness of the proposed contract design scheme for cooperative relay.

An investigation of the mechanical behavior of initially curved microplates under electrostatic actuation

KAUST Repository

Saghir, Shahid

2018-03-28

In this article, we investigate the mechanical behavior of initially curved microplates under electrostatic actuation. Microplates are essential components of many Micro-Electro-Mechanical System devices; however, they commonly undergo an initial curvature imperfection, due to the microfabrication process. Initial curvature imperfection significantly affects the mechanical behavior of microplates. In this work, we derive a dynamic analogue of the von Kármán governing equation for such plates. These equations are then used to develop a reduced order model based on the Galerkin procedure to simulate the static and dynamic behavior of the microplate. Two profiles of initial curvature commonly encountered in microfabricated structures are considered, where one assumes a variation in shape along one dimension of the plate only (cylindrical bending shape) while the other assumes a variation in shape along both dimensions of the plate. Their effects on both the static and dynamic responses of the microplates are examined and compared. We validate the reduced order model by comparing the calculated static behavior and the fundamental natural frequency with those computed by a finite element model over a range of the initial plate rise. The static behavior of the microplate is investigated when varying the DC voltage. Then, the dynamic behavior of the microplate is examined under the application of a harmonic AC voltage superimposed to a DC voltage.

POSSIBLE MECHANISMS UNDERLYING THE THERAPEUTIC EFFECTS OF TRANSCRANIAL MAGNETIC STIMULATION

Directory of Open Access Journals (Sweden)

Alexander eChervyakov

2015-06-01

Full Text Available Transcranial magnetic stimulation (TMS is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson's disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation (LTP and long-term depression (LTD. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor (BDNF concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals. It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols.

Evaluating Public Plantation and Community Planted Forests under the CDM and REDD+ Mechanism for Carbon Stock in Nepal

Directory of Open Access Journals (Sweden)

Ram Asheshwar MANDAL

2013-09-01

Full Text Available Public plantations (PPs and Community planted forests (CPFs are inimitable types of participatory forest management practices in Nepal, but their eligibility issues under the framework of clean development mechanism (CDM and reducing emission from the deforestation and forest degradation mechanism (REDD+ are not evaluated. So, to explore the management system of PP and CPF, we compared forest carbon stocks in plantations and evaluated these plantations under these mechanisms as objectives of this research. The relevant documents were revised and altogether 55 samples were collected from Shreepur, Banauta and Bisbity PPs and Sita, Ramnagar and Jogikuti CPFs, in Mahottary district, Nepal. The equation of Chave et al was used to calculate the biomass, which was further converted into carbon. Meanwhile, management practices were evaluated under the framework of CDM and REDD+. The PPs are public land managed, especially by disadvantaged communities, while CPFs are the patches of national forest managed by users. The variation in carbon stock was found to be highest (148.89 ton ha-1 in Sita CPF and lowest (30.34 ton ha-1 in Bisbitty PP. In fact, it is difficult to certify plantations under CDM, due to its complexity, but they can easily be candidate to the REDD+ mechanism, if they are bundled with large forest blocks.

Underlying Mechanisms of Tinnitus: Review and Clinical Implications

Science.gov (United States)

Henry, James A.; Roberts, Larry E.; Caspary, Donald M.; Theodoroff, Sarah M.; Salvi, Richard J.

2016-01-01

Background The study of tinnitus mechanisms has increased tenfold in the last decade. The common denominator for all of these studies is the goal of elucidating the underlying neural mechanisms of tinnitus with the ultimate purpose of finding a cure. While these basic science findings may not be immediately applicable to the clinician who works directly with patients to assist them in managing their reactions to tinnitus, a clear understanding of these findings is needed to develop the most effective procedures for alleviating tinnitus. Purpose The goal of this review is to provide audiologists and other health-care professionals with a basic understanding of the neurophysiological changes in the auditory system likely to be responsible for tinnitus. Results It is increasingly clear that tinnitus is a pathology involving neuroplastic changes in central auditory structures that take place when the brain is deprived of its normal input by pathology in the cochlea. Cochlear pathology is not always expressed in the audiogram but may be detected by more sensitive measures. Neural changes can occur at the level of synapses between inner hair cells and the auditory nerve and within multiple levels of the central auditory pathway. Long-term maintenance of tinnitus is likely a function of a complex network of structures involving central auditory and nonauditory systems. Conclusions Patients often have expectations that a treatment exists to cure their tinnitus. They should be made aware that research is increasing to discover such a cure and that their reactions to tinnitus can be mitigated through the use of evidence-based behavioral interventions. PMID:24622858

Activation delay-induced mechanical dyssynchrony in single-ventricle heart disease

DEFF Research Database (Denmark)

Forsha, Daniel; Risum, Niels; Barker, Piers

2017-01-01

We present the case of an infant with a single functional ventricle who developed ventricular dysfunction and heart failure due to an electrical activation delay and dyssynchrony. Earlier recognition of this potentially reversible aetiology may have changed her poor outcome.......We present the case of an infant with a single functional ventricle who developed ventricular dysfunction and heart failure due to an electrical activation delay and dyssynchrony. Earlier recognition of this potentially reversible aetiology may have changed her poor outcome....

Diet and the microbial aetiology of dental caries: new paradigms.

Science.gov (United States)

Bradshaw, David J; Lynch, Richard J M

2013-12-01

The microbial and dietary factors that drive caries have been studied scientifically for 120 years. Frequent and/or excessive sugar (especially sucrose) consumption has been ascribed a central role in caries causation, while Streptococcus mutans appeared to play the key role in metabolising sucrose to produce lactic acid, which can demineralise enamel. Many authors described caries as a transmissible infectious disease. However, more recent data have shifted these paradigms. Streptococcus mutans does not fulfil Koch's postulates - presence of the organism leading to disease, and absence of the organism precluding disease. Furthermore, molecular microbiological methods have shown that, even with a sugar-rich diet, a much broader spectrum of acidogenic microbes is found in dental plaque. While simple sugars can be cariogenic, cooked starches are also now recognised to be a caries threat, especially because such starches, while not 'sticky in the hand', can be highly retentive in the mouth. Metabolism of starch particles can yield a prolonged acidic challenge, especially at retentive, caries-prone sites. These changes in the paradigms of caries aetiology have important implications for caries control strategies. Preventing the transmission of S. mutans will likely be inadequate to prevent caries if a sufficiently carbohydrate-rich diet continues. Similarly, restriction of sucrose intake, although welcome, would be unlikely to be a panacea for caries, especially if frequent starch intake persisted. Instead, approaches to optimise fluoride delivery, to target plaque acidogenicity or acidogenic microbes, to promote plaque alkali generation, to increase salivary flow or replace fermentable carbohydrates with non-fermentable alternatives may be more promising. © 2013 FDI World Dental Federation.

Pseudotumour cerebri in children: Aetiology, clinical features, and progression.

Science.gov (United States)

Mosquera Gorostidi, A; Iridoy Zulet, M; Azcona Ganuza, G; Gembero Esarte, E; Yoldi Petri, M E; Aguilera Albesa, S

2017-01-09

The definition, associated aetiologies, diagnosis, and treatment of idiopathic intracranial hypertension, or pseudotumour cerebri (PTC), are constantly being revised in the paediatric population. Our study included children younger than 15 years old with PTC and attended at a reference hospital in the past 12 years. We analysed the clinical and epidemiological features of our sample and the diagnostic and treatment approaches. PTC was defined as presence of intracranial hypertension (CSF opening pressure>25cmH 2 O) and absence of space-occupying lesions in brain MR images. A total of 12 children with PTC were included; mean age was 10 years and 90% were girls. Weight was normal in all patients. Eighty-two percent of the patients had symptoms: headache (66%), diplopia (8%), and visual loss (8%). All of them displayed papilloedema (17% unilaterally). Lumbar puncture (LP) provided the diagnosis in all cases and 91% showed no relevant MRI findings. A potential cause of PTC was identified in 5 cases: pharmacological treatment in 2 and infection (Mycoplasma pneumoniae [M. pneumoniae]) in 3. Ninety-one per cent of the patients received treatment: 75% underwent several LPs and 42% received acetazolamide and/or prednisone. Outcomes were favourable in all cases. The incidence of PTC was estimated at approximately 1 case per 100 000 children/years, in line with data reported by previous studies. Overweight was not found to be a risk factor for PTC in this population. M. pneumoniae infection may trigger PTC and cause recurrences at later stages. The absence of symptoms seems to be independent from the degree of intracranial hypertension. Acetazolamide treatment is effective in most cases, and it represents a viable alternative to repeated LP. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.

A fracture mechanics study of tungsten failure under high heat flux loads

International Nuclear Information System (INIS)

Li, Muyuan

2015-01-01

The performance of fusion devices is highly dependent on plasma-facing components. Tungsten is the most promising candidate material for armors in plasma-facing components in ITER and DEMO. However, the brittleness of tungsten below the ductile-to-brittle transition temperature is very critical to the reliability of plasma-facing components. In this work, thermo-mechanical and fracture behaviors of tungsten are predicted numerically under fusion relevant thermal loadings.

Effect of fuel assembly mechanical design changes on dynamic response of reactor pressure vessel system under extreme loadings

International Nuclear Information System (INIS)

Bhandari, D.R.; Hankinson, M.F.

1993-01-01

This paper presents the results of a study to assess the effect of fuel assembly mechanical design changes on the dynamic response of a pressurized water reactor vessel and reactor internals under Loss-Of-Coolant Accident (LOCA) conditions. The results of this study show that the dynamic response of the reactor vessel internals and the core under extreme loadings, such as LOCA, is very sensitive to fuel assembly mechanical design changes. (author)

Study of the changes in the magnetic properties of stainless steels under mechanical treatment

Energy Technology Data Exchange (ETDEWEB)

Iankov, R.; Rusanov, V., E-mail: rusanov@phys.uni-sofia.bg [Magna Powertrain Ltd., Industrial Zone Rakowski (Bulgaria); Paneva, D.; Mitov, I. [Institute of Catalysis, Bulgarian Academy of Sciences (Bulgaria); Trautwein, A. X. [Institut für Physik, Universität zu Lübeck (Germany)

2016-12-15

Six types of stainless steels (SS) were studied for changes in its structure and magnetic properties under mechanical treatment. Depending on intensity and duration of the process of plastic deformation and the SS type the paramagnetic austenite structure transforms partially to completely into ferrite structure with ferromagnetic behaviour. Some of the SS tested were found slightly modified yet in the process of its manufacturing. Only one SS type with high Ni content preserved its structure and paramagnetic properties even after very intense mechanical treatment.

Supernatural beliefs, aetiological models and help seeking behaviour in patients with schizophrenia.

Science.gov (United States)

Kate, Natasha; Grover, Sandeep; Kulhara, Parmanand; Nehra, Ritu

2012-01-01

Few studies have evaluated the supernatural beliefs of patients with schizophrenia. This study aimed to study the personal beliefs, aetiological models and help seeking behaviour of patients with schizophrenia using a self-rated questionnaire. Seventy three patients returned the completed supernatural Attitude questionnaire. 62% of patients admitted that people in their community believed in sorcery and other magico-religious phenomena. One fourth to half of patients believed in ghosts/evil spirit (26%), spirit intrusion (28.8%) and sorcery (46.6%). Two-third patients believed that mental illness can occur either due to sorcery, ghosts/evil spirit, spirit intrusion, divine wrath, planetary/astrological influences, dissatisfied or evil spirits and bad deeds of the past. 40% of the subjects attributed mental disorders to more than one of these beliefs. About half of the patients (46.6%) believed that only performance of prayers was sufficient to improve their mental status. Few patients (9.6%) believed that magico-religious rituals were sufficient to improve their mental illness but about one-fourth (24.7%) admitted that during recent episode either they or their caregivers performed magico-religious rituals. Supernatural beliefs are common in patients with schizophrenia and many of them attribute the symptoms of mental disorders to these beliefs.

Aetiological factors contributing to road traffic accidents in Riyadh City, Saudi Arabia.

Science.gov (United States)

Nofal, F H; Saeed, A A; Anokute, C C

1996-10-01

The study analysed 13,390 police records of road traffic accidents (RTAs) covering a three and a half year period according to different suspected aetiological factors. The majority of the accidents were recorded for vehicles in good condition on well-paved straight roads with well-operating traffic light systems. Adverse weather conditions such as precipitation, fog and dust were of minimal importance, with most of the accidents being reported during sunny days during the rush period of 12 noon to 3 pm. Driver's error was identified as the main contributing factor in about two thirds of all RTAs mainly as reckless driving and excess speeding. About 27% of the drivers were professional drivers and 41% were in the age group 25-35 years in good health with no alcohol or drug intake. Hence, human errors may be attributed to carelessness, experience, lack of knowledge or attention, over-exhaustion or fatigue. The effects of physical stressors on performance of drivers need to be further explored and clarified but this need not underestimate the importance of vehicle and environment since most accidents are multifactoral and a slight change in them may effectively enhance perception and minimise personal error. Recommendations for remedial measures adopting an interdisciplinary approach are presented.

Different intra- and interspecific facilitation mechanisms between two Mediterranean trees under a climate change scenario.

Science.gov (United States)

Gimeno, Teresa E; Escudero, Adrián; Valladares, Fernando

2015-01-01

In harsh environments facilitation alleviates biotic and abiotic constraints on tree recruitment. Under ongoing drier climate change, we expect facilitation to increase as a driver of coexistence. However, this might not hold under extreme abiotic stress and when the outcome depends on the interaction with other drivers such as altered herbivore pressure due to land use change. We performed a field water-manipulation experiment to quantify the importance of facilitation in two coexisting Mediterranean trees (dominant Juniperus thurifera and coexisting Quercus ilex subsp. ballota) under a climate change scenario. Shifts in canopy dominance favouring Q. ilex could be based on the extension of heterospecific facilitation to the detriment of conspecific alleviation. We found that saplings of both species transplanted under the canopy of nurse trees had greater survival probability, growth and photochemical efficiency. Intra- and interspecific facilitation mechanisms differed: alleviation of abiotic stress benefited both species during summer and J. thurifera during winter, whereas browsing protection was relevant only for Q. ilex. Facilitation was greater under the dry treatment only for Q. ilex, which partially agreed with the predictions of the stress gradient hypothesis. We conclude that present rainfall availability limits neither J. thurifera nor Q. ilex establishment. Nevertheless, under current global change scenarios, imposing increasing abiotic stress together with altered herbivore browsing, nurse trees could differentially facilitate the establishment of Q. ilex due to species-specific traits, i.e. palatability; drought, heat and cold tolerance, underlying species differences in the facilitation mechanisms and eventually triggering a change from pure juniper woodlands to mixed formations.

The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

International Nuclear Information System (INIS)

Tian, Dayong; Lin, Zhifen; Zhou, Xianghong; Yin, Daqiang

2013-01-01

Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptors of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E binding ), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. • Two generic

The underlying toxicological mechanism of chemical mixtures: A case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum

Energy Technology Data Exchange (ETDEWEB)

Tian, Dayong [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Department of Chemical and Environmental Engineering, Anyang Institute of Technology, Anyang 455000 (China); Lin, Zhifen, E-mail: lzhifen@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Zhou, Xianghong [Department of Public Management, Tongji University, Shanghai 200092 (China); Yin, Daqiang [Key Laboratory of Yangtze River Water Environment, Ministry of Education, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

2013-10-15

Intracellular chemical reaction of chemical mixtures is one of the main reasons that cause synergistic or antagonistic effects. However, it still remains unclear what the influencing factors on the intracellular chemical reaction are, and how they influence on the toxicological mechanism of chemical mixtures. To reveal this underlying toxicological mechanism of chemical mixtures, a case study on mixture toxicity of cyanogenic toxicants and aldehydes to Photobacterium phosphoreum was employed, and both their joint effects and mixture toxicity were observed. Then series of two-step linear regressions were performed to describe the relationships between joint effects, the expected additive toxicities and descriptors of individual chemicals (including concentrations, binding affinity to receptors, octanol/water partition coefficients). Based on the quantitative relationships, the underlying joint toxicological mechanisms were revealed. The result shows that, for mixtures with their joint effects resulting from intracellular chemical reaction, their underlying toxicological mechanism depends on not only their interaction with target proteins, but also their transmembrane actions and their concentrations. In addition, two generic points of toxicological mechanism were proposed including the influencing factors on intracellular chemical reaction and the difference of the toxicological mechanism between single reactive chemicals and their mixtures. This study provided an insight into the understanding of the underlying toxicological mechanism for chemical mixtures with intracellular chemical reaction. - Highlights: • Joint effects of nitriles and aldehydes at non-equitoxic ratios were determined. • A novel descriptor, ligand–receptor interaction energy (E{sub binding}), was employed. • Quantitative relationships for mixtures were developed based on a novel descriptor. • The underlying toxic mechanism was revealed based on quantitative relationships. • Two

Experimental study of the anisotropic properties of argillite under moisture and mechanical loads

International Nuclear Information System (INIS)

Yang, D.S.; Chanchole, S.; Wang, L.L.; Bornert, M.; Gatmiri, B.

2012-01-01

Document available in extended abstract form only. Due to various factors, such as sedimentation, layered morphology of clay mineral, in-situ stress, etc., the behavior of argillite rocks is often anisotropic. In order to study the anisotropy of the Callovo-Oxfordian (COx) argillite considered as a possible host rock for high-level radioactive nuclear waste repository in France, a series of tests including uniaxial compression and dehydration and hydration at different constant applied stress levels, are carried out using a specific setup combining mechanical and moisture loading devices. During these hydro-mechanical tests, this specific setup can also continuously capture images of the sample surfaces to be subsequently analyzed using Digital Image Correlation techniques (DIC) in order to determine full-field strains. In this study, three sampling directions are used with the angle θ between the bedding plane and the cylindrical sample axis equal to 45 deg., 60 deg. and 90 deg.. To investigate the mechanical anisotropy, uniaxial compressive tests with mechanical loading and unloading cycles are performed on several different samples at the same moisture level. The results show that the mechanical parameters (apparent modulus, failure stress) depend on loading orientation relative to the stratification plane. For a given water content, the failure stress reaches maximum values for θ =90 deg. and minimum values for θ =45 deg.. To study the hydric anisotropy, dehydration and hydration tests under stress-free conditions are performed on two cylindrical samples (θ=90 deg. and θ=60 deg.). Three cycles of hydration and dehydration are carried out by varying the relative humidity between 40% and 95%. The sample weight, the deformation measured by strain gages and the relative humidity are continuously recorded during the test by means of another specific setup described in [Pham et al., 2007]. Fig.1a illustrates the evolution of the strains of the sample EST28030-No

A numerical study of crack interactions under thermo-mechanical load using EFGM

International Nuclear Information System (INIS)

Pant, Mohit; Singh, I. V.; Mishra, B. K.

2011-01-01

In this work, element free Galerkin method (EFGM) has been used to obtain the solution of various edge crack problems under thermo-mechanical loads as it provides a versatile technique to model stationary as well as moving crack problems without re-meshing. Standard diffraction criterion has been modified with multiple crack weight technique to characterize the presence of various cracks in the domain of influence of a particular node. The effect of crack inclination has been studied for single as well as two edge cracks, whereas the cracks interaction has been studied for two edge cracks lying on same as well as opposite edges under plane stress conditions. The values of mode-I and mode-II stress intensity factors have been evaluated by the interaction integral approach

Temperature-dependent dynamic mechanical properties of magnetorheological elastomers under magnetic field

Energy Technology Data Exchange (ETDEWEB)

Ju, Benxiang, E-mail: jubenxiang@qq.com [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Tang, Rui; Zhang, Dengyou; Yang, Bailian [National Instrument Functional Materials Engineering Technology Research Center, Chongqing 400707 (China); Yu, Miao; Liao, Changrong [College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

2015-01-15

Both anisotropic and isotropic magnetorheological elastomer (MRE) samples were fabricated by using as-prepared polyurethane (PU) matrix and carbonyl iron particles. Temperature-dependent dynamic mechanical properties of MRE were investigated and analyzed. Due to the unique structural features of as-prepared matrix, temperature has a greater impact on the properties of as-prepared MRE, especially isotropic MRE. With increasing of temperature and magnetic field, MR effect of isotropic MRE can reach up to as high as 4176.5% at temperature of 80 °C, and the mechanism of the temperature-dependent in presence of magnetic field was discussed. These results indicated that MRE is a kind of temperature-dependent material, and can be cycled between MRE and MR plastomer (MRP) by varying temperature. - Highlights: • Both anisotropic and isotropic MRE were fabricated by using as-prepared matrix. • Temperature-dependent properties of MRE under magnetic field were investigated. • As-prepared MRE can transform MRE to MRP by adjusting temperature.

Mechanical properties and fracture behaviour of defective phosphorene nanotubes under uniaxial tension

Science.gov (United States)

Liu, Ping; Pei, Qing-Xiang; Huang, Wei; Zhang, Yong-Wei

2017-12-01

The easy formation of vacancy defects and the asymmetry in the two sublayers of phosphorene nanotubes (PNTs) may result in brand new mechanical properties and failure behaviour. Herein, we investigate the mechanical properties and fracture behaviour of defective PNTs under uniaxial tension using molecular dynamics simulations. Our simulation results show that atomic vacancies cause local stress concentration and thus significantly reduce the fracture strength and fracture strain of PNTs. More specifically, a 1% defect concentration is able to reduce the fracture strength and fracture strain by as much as 50% and 66%, respectively. Interestingly, the reduction in the mechanical properties is found to depend on the defect location: a defect located in the outer sublayer has a stronger effect than one located in the inner layer, especially for PNTs with a small diameter. Temperature is also found to strongly influence the mechanical properties of both defect-free and defective PNTs. When the temperature is increased from 0 K to 400 K, the fracture strength and fracture strain of defective PNTs with a defect concentration of 1% are reduced further by 71% and 61%, respectively. These findings are of great importance for the structural design of PNTs as building blocks in nanodevices.

Magnetization reversal mechanisms under oblique magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Ntallis, N.; Efthimiadis, K.G., E-mail: kge@auth.gr

2017-03-01

In this work finite element micromagnetic simulations were performed in order to study the reversal mechanisms of spherical ferromagnetic particles with uniaxial magnetocrystalline anisotropy, when they are magnetized along an oblique direction with respect to the anisotropy axis. Magnetization loops are taken in different directions of external magnetic field, at different anisotropy constants and particle sizes. In the simulation results, the three reversal mechanisms (coherent, curling and domains) are observed and new phenomena arise due to the action of oblique magnetic fields. Moreover, the dependence of the critical fields with respect to the angle of the external field is presented. - Highlights: • Finite element micromagnetic simulation of the three different reversal mechanisms. • For the curling mechanism, the new phenomenon is the rotation of the vortex. • In the domain reversal mechanism, the formed domain wall is smaller than 180°. • In soft ferromagnetic particles a rearrangement of the magnetic domains is observed.

Simulated airplane headache: a proxy towards identification of underlying mechanisms.

Science.gov (United States)

Bui, Sebastian Bao Dinh; Petersen, Torben; Poulsen, Jeppe Nørgaard; Gazerani, Parisa

2017-12-01

Airplane Headache (AH) occurs during flights and often appears as an intense, short lasting headache during take-off or landing. Reports are limited on pathological mechanisms underlying the occurrence of this headache. Proper diagnosis and treatments would benefit from identification of potential pathways involved in AH pathogenesis. This study aimed at providing a simulated airplane headache condition as a proxy towards identification of its underlying mechanisms. Fourteen participants including 7 volunteers suffering from AH and 7 healthy matched controls were recruited after meeting the diagnostic and safety criteria based on an approved study protocol. Simulation of AH was achieved by entering a pressure chamber with similar characteristics of an airplane flight. Selected potential biomarkers including salivary prostaglandin E 2 (PGE 2 ), cortisol, facial thermo-images, blood pressure, pulse, and saturation pulse oxygen (SPO) were defined and values were collected before, during and after flight simulation in the pressure chamber. Salivary samples were analyzed with ELISA techniques, while data analysis and statistical tests were handled with SPSS version 22.0. All participants in the AH-group experienced a headache attack similar to AH experience during flight. The non-AH-group did not experience any headaches. Our data showed that the values for PGE 2 , cortisol and SPO were significantly different in the AH-group in comparison with the non-AH-group during the flight simulation in the pressure chamber. The pressure chamber proved useful not only to provoke AH-like attack but also to study potential biomarkers for AH in this study. PGE 2 , and cortisol levels together with SPO presented dysregulation during the simulated AH-attack in affected individuals compared with healthy controls. Based on these findings we propose to use pressure chamber as a model to induce AH, and thus assess new potential biomarkers for AH in future studies.

Neurodevelopmental Disorders and Environmental Toxicants: Epigenetics as an Underlying Mechanism

Science.gov (United States)

2017-01-01

The increasing prevalence of neurodevelopmental disorders, especially autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), calls for more research into the identification of etiologic and risk factors. The Developmental Origin of Health and Disease (DOHaD) hypothesizes that the environment during fetal and childhood development affects the risk for many chronic diseases in later stages of life, including neurodevelopmental disorders. Epigenetics, a term describing mechanisms that cause changes in the chromosome state without affecting DNA sequences, is suggested to be the underlying mechanism, according to the DOHaD hypothesis. Moreover, many neurodevelopmental disorders are also related to epigenetic abnormalities. Experimental and epidemiological studies suggest that exposure to prenatal environmental toxicants is associated with neurodevelopmental disorders. In addition, there is also evidence that environmental toxicants can result in epigenetic alterations, notably DNA methylation. In this review, we first focus on the relationship between neurodevelopmental disorders and environmental toxicants, in particular maternal smoking, plastic-derived chemicals (bisphenol A and phthalates), persistent organic pollutants, and heavy metals. We then review studies showing the epigenetic effects of those environmental factors in humans that may affect normal neurodevelopment. PMID:28567415

MECHANICAL BEHAVIOR OF PRESTRESSED VISCOELASTIC ADHESIVE AREAS UNDER COMBINING LOADINGS

Directory of Open Access Journals (Sweden)

Halil Murat Enginsoy

2017-12-01

Full Text Available In this article, mechanical behaviors of adhesive tape VHB 4950 elastomeric material, which is an element of acrylic polymer group and which is in viscoelastic behavior, under different pre-stress conditions and complex forces of different geometric parameters created by combining loadings have been experimentally and numerically investigated. In experimental studies, loading-unloading cyclic tests, one of the different standardized tests for the mechanical characterization of viscoelastic material, have been applied which give the most suitable convergent optimization parameters for the finite element model. Different material models were also investigated by using the data obtained from loading-unloading test results in all numerical models. According to the experimental results, the most suitable material parameters were determined with the Abaqus Parallel Rheological Framework Model (PRF for 4 Yeoh Networks with Bergstrom-Boyce Flow model created in the Mcalibration software for finite element analysis. Subsequently, using these material parameters, finite element analysis was performed as three dimension non-linear viscoelastic with a commercial finite element software Abaqus. The finite element analysis results showed good correlation to the Force (N-Displacement (mm experimental data for maximum load-carrying capacity of structural specimens.

Neurodevelopmental Disorders and Environmental Toxicants: Epigenetics as an Underlying Mechanism

Directory of Open Access Journals (Sweden)

Nguyen Quoc Vuong Tran

2017-01-01

Full Text Available The increasing prevalence of neurodevelopmental disorders, especially autism spectrum disorders (ASD and attention deficit hyperactivity disorder (ADHD, calls for more research into the identification of etiologic and risk factors. The Developmental Origin of Health and Disease (DOHaD hypothesizes that the environment during fetal and childhood development affects the risk for many chronic diseases in later stages of life, including neurodevelopmental disorders. Epigenetics, a term describing mechanisms that cause changes in the chromosome state without affecting DNA sequences, is suggested to be the underlying mechanism, according to the DOHaD hypothesis. Moreover, many neurodevelopmental disorders are also related to epigenetic abnormalities. Experimental and epidemiological studies suggest that exposure to prenatal environmental toxicants is associated with neurodevelopmental disorders. In addition, there is also evidence that environmental toxicants can result in epigenetic alterations, notably DNA methylation. In this review, we first focus on the relationship between neurodevelopmental disorders and environmental toxicants, in particular maternal smoking, plastic-derived chemicals (bisphenol A and phthalates, persistent organic pollutants, and heavy metals. We then review studies showing the epigenetic effects of those environmental factors in humans that may affect normal neurodevelopment.

Prediction study on mechanical and thermodynamic properties of orthorhombic Mg2SiO4 under high temperature

International Nuclear Information System (INIS)

Zhou, Jianting; Zhang, Hong; Chen, Yue; Shong, Jun; Chen, Zhuo; Yang, Juan; Zheng, Zhou; Wang, Feng

2014-01-01

In this work, based on density functional theory and quasi-harmonic Debye model, mechanical and thermodynamic properties of orthorhombic Mg 2 SiO 4 under high temperature are predicted. We found out that α-Mg 2 SiO 4 is mechanically stable under the condition from about 0 to 74 GPa. Results indicate that the main cause of mechanical instability is high pressure, and the effect caused by high temperature is small. C 11 , C 22 , C 33 , B and v p reduce with temperature just a little and increase with pressure obviously. Mg 2 SiO 4 has excellent resistance to strong compression; however the resistance to shear is unsatisfactory. The C v tends to the Petit and Dulong limit at high temperature under any pressure, and it is proportional to T 3 at extremely low temperature. Pressure has an opposite effect on C v than temperature. The suppressed effect on C v caused by pressure is not obvious under low and very high temperature. Mg 2 SiO 4 has three different thermal expansion coefficients (α) along a-, b- and c-axes, and α a <α c <α b . α increases rapidly at low temperature (about <300 K), and slows down at high temperature. High pressure would greatly suppress expansion caused by temperature. Nevertheless, increasing tendency of α b and α c is still obvious under high pressure, especially α b . All the properties are mainly due to Si–O covalent bonds and their directions

Estimation of mechanical properties of gelatin using a microbubble under acoustic radiation force

International Nuclear Information System (INIS)

Shirota, Eriko; Ando, Keita

2015-01-01

This paper is concerned with observations of the translation of a microbubble (80 μm or 137 μm in radius) in a viscoelastic medium (3 w% gelatin), which is induced by acoustic radiation force originating from 1 MHz focused ultrasound. An optical system using a high-speed camera was designed to visualize the bubble translation and deformation. If the bubble remains its spherical shape under the sonication, the bubble translation we observed can be described by theory based on the Voigt model for linear viscoelastic solids; mechanical properties of the gelatin are calculated from measurements of the terminal displacement under the sonication. (paper)

Estimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015.

Science.gov (United States)

2017-11-01

The Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2015 provides an up-to-date analysis of the burden of lower respiratory tract infections (LRIs) in 195 countries. This study assesses cases, deaths, and aetiologies spanning the past 25 years and shows how the burden of LRI has changed in people of all ages. We estimated LRI mortality by age, sex, geography, and year using a modelling platform shared across most causes of death in the GBD 2015 study called the Cause of Death Ensemble model. We modelled LRI morbidity, including incidence and prevalence, using a meta-regression platform called DisMod-MR. We estimated aetiologies for LRI using two different counterfactual approaches, the first for viral pathogens, which incorporates the aetiology-specific risk of LRI and the prevalence of the aetiology in LRI episodes, and the second for bacterial pathogens, which uses a vaccine-probe approach. We used the Socio-demographic Index, which is a summary indicator derived from measures of income per capita, educational attainment, and fertility, to assess trends in LRI-related mortality. The two leading risk factors for LRI disability-adjusted life-years (DALYs), childhood undernutrition and air pollution, were used in a decomposition analysis to establish the relative contribution of changes in LRI DALYs. In 2015, we estimated that LRIs caused 2·74 million deaths (95% uncertainty interval [UI] 2·50 million to 2·86 million) and 103·0 million DALYs (95% UI 96·1 million to 109·1 million). LRIs have a disproportionate effect on children younger than 5 years, responsible for 704 000 deaths (95% UI 651 000-763 000) and 60.6 million DALYs (95ÙI 56·0-65·6). Between 2005 and 2015, the number of deaths due to LRI decreased by 36·9% (95% UI 31·6 to 42·0) in children younger than 5 years, and by 3·2% (95% UI -0·4 to 6·9) in all ages. Pneumococcal pneumonia caused 55·4% of LRI deaths in all ages, totalling 1 517 388 deaths (95% UI 857 940

Underlying mechanism of drug-drug interaction between pioglitazone and gemfibrozil: Gemfibrozil acyl-glucuronide is a mechanism-based inhibitor of CYP2C8.

Science.gov (United States)

Takagi, Motoi; Sakamoto, Masaya; Itoh, Tomoo; Fujiwara, Ryoichi

2015-08-01

While co-administered gemfibrozil can increase the area under the concentration/time curve (AUC) of pioglitazone more than 3-fold, the underlying mechanism of the drug-drug interaction between gemfibrozil and pioglitazone has not been fully understood. In the present study, gemfibrozil preincubation time-dependently inhibited the metabolism of pioglitazone in the cytochrome P450 (CYP)- and UDP-glucuronosyltransferase (UGT)-activated human liver microsomes. We estimated the kinact and K'app values, which are the maximum inactivation rate constant and the apparent dissociation constant, of gemfibrozil to be 0.071 min(-1) and 57.3 μM, respectively. In this study, the kobs, in vivo value was defined as a parameter that indicates the potency of the mechanism-based inhibitory effect at the blood drug concentration in vivo. The kobs, in vivo values of potent mechanism-based inhibitors, clarithromycin and erythromycin, were estimated to be 0.0096 min(-1) and 0.0051 min(-1), respectively. The kobs, in vivo value of gemfibrozil was 0.0060 min(-1), which was comparable to those of clarithromycin and erythromycin, suggesting that gemfibrozil could be a mechanism-based inhibitor as potent as clarithromycin and erythromycin in vivo. Copyright © 2015 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Tracing environmental aetiological factors of chronic kidney diseases in the dry zone of Sri Lanka-A hydrogeochemical and isotope approach.

Science.gov (United States)

Wickramarathna, Sudeera; Balasooriya, Shyamalie; Diyabalanage, Saranga; Chandrajith, Rohana

2017-12-01

Chronic kidney disease of unknown aetiologies (CKDu) is increasingly recognized in tropical regions and is now considered a global health problem. A detailed hydrogeochemical investigation has been performed in three CKDu hotspots in Sri Lanka to assess the geo-environmental aetiological factors influencing this disease. A total of 71 ground- and 26 surface water samples were collected from Girandurukotte, Wilgamuwa and Nikawewa regions and analysed for major constituents and trace elements. The affected regions are dominated by Ca-Mg-HCO 3 facies groundwater that is mainly controlled by silicate weathering. Higher levels of fluoride associated with higher hardness is the main feature of groundwater from CKDu regions compared to non-CKDu regions. Results showed that 65% of the wells in the affected regions exceeded the fluoride concentration of 0.5mg/L. Environmental isotopes of groundwater in the CKDu regions are represented by the regression line of δ 2 H=5.42δ 18 O-3.59 (r 2 =0.916) with a clear isotopic differentiation between local precipitation and groundwater. None of the trace elements exceeded the recommended scales and in most cases levels are negligible in both surface and groundwater in study areas. Therefore, the involvement of trace elements such as Cd, As and Pb can be ignored as causative factors for CKDu. This study highlights the synergistic influence of fluoride and hardness that could enhance the disease, and thereby refute earlier theories that attribute trace elements as causative factors for CKDu. Higher hardness in drinking water also restricts sufficient water uptake, particularly by farmers and which affects the physiological, biochemical and nutritional requirements. Copyright © 2017 Elsevier GmbH. All rights reserved.

Mechanisms Underlying the Anti-Aging and Anti-Tumor Effects of Lithocholic Bile Acid

Directory of Open Access Journals (Sweden)

Anthony Arlia-Ciommo

2014-09-01

Full Text Available Bile acids are cholesterol-derived bioactive lipids that play essential roles in the maintenance of a heathy lifespan. These amphipathic molecules with detergent-like properties display numerous beneficial effects on various longevity- and healthspan-promoting processes in evolutionarily distant organisms. Recent studies revealed that lithocholic bile acid not only causes a considerable lifespan extension in yeast, but also exhibits a substantial cytotoxic effect in cultured cancer cells derived from different tissues and organisms. The molecular and cellular mechanisms underlying the robust anti-aging and anti-tumor effects of lithocholic acid have emerged. This review summarizes the current knowledge of these mechanisms, outlines the most important unanswered questions and suggests directions for future research.

Inflammatory mechanisms in Alzheimer's disease

NARCIS (Netherlands)

Eikelenboom, P.; Zhan, S. S.; van Gool, W. A.; Allsop, D.

1994-01-01

Alzheimer's disease is aetiologically heterogeneous, but the pathogenesis is often considered to be initiated by the deposition of amyloid fibrils, followed by neuritic tau pathology and neuronal death. A variety of inflammatory proteins has been identified in the brains of patients with Alzheimer's

Binocular diplopia in a tertiary hospital: Aetiology, diagnosis and treatment.

Science.gov (United States)

Merino, P; Fuentes, D; Gómez de Liaño, P; Ordóñez, M A

2017-12-01

To study the causes, diagnosis and treatment in a case series of binocular diplopia. A retrospective chart review was performed on patients seen in the Diplopia Unit of a tertiary centre during a one-year period. Diplopia was classified as: acute≤1 month since onset; subacute (1-6 months); and chronic (>6 months). Resolution of diplopia was classified as: spontaneous if it disappeared without treatment, partial if the course was intermittent, and non-spontaneous if treatment was required. It was considered a good outcome when diplopia disappeared completely (with or without treatment), or when diplopia was intermittent without significantly affecting the quality of life. A total of 60 cases were included. The mean age was 58.65 years (60% female). An acute or subacute presentation was observed in 60% of the patients. The mean onset of diplopia was 82.97 weeks. The most frequent aetiology was ischaemic (45%). The most frequent diagnosis was sixth nerve palsy (38.3%), followed by decompensated strabismus (30%). Neuroimaging showed structural lesions in 17.7% of the patients. There was a spontaneous resolution in 28.3% of the cases, and there was a good outcome with disappearance of the diplopia in 53.3% at the end of the study. The most frequent causes of binocular diplopia were cranial nerve palsies, especially the sixth cranial nerve, followed by decompensated strabismus. Structural lesions in imaging tests were more than expected. Only one third of patients had a spontaneous resolution, and half of them did not have a good outcome despite of treatment. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Mechanical Behavior of Red Sandstone under Incremental Uniaxial Cyclical Compressive and Tensile Loading

Directory of Open Access Journals (Sweden)

Baoyun Zhao

2017-01-01

Full Text Available Uniaxial experiments were carried out on red sandstone specimens to investigate their short-term and creep mechanical behavior under incremental cyclic compressive and tensile loading. First, based on the results of short-term uniaxial incremental cyclic compressive and tensile loading experiments, deformation characteristics and energy dissipation were analyzed. The results show that the stress-strain curve of red sandstone has an obvious memory effect in the compressive and tensile loading stages. The strains at peak stresses and residual strains increase with the cycle number. Energy dissipation, defined as the area of the hysteresis loop in the stress-strain curves, increases nearly in a power function with the cycle number. Creep test of the red sandstone was also conducted. Results show that the creep curve under each compressive or tensile stress level can be divided into decay and steady stages, which cannot be described by the conventional Burgers model. Therefore, an improved Burgers creep model of rock material is constructed through viscoplastic mechanics, which agrees very well with the experimental results and can describe the creep behavior of red sandstone better than the Burgers creep model.

The tunable mechanical property of water-filled carbon nanotubes under an electric field

Science.gov (United States)

Ye, Hongfei; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen; Zong, Zhi; Zheng, Yonggang

2014-03-01

The spring-induced compression of water-filled carbon nanotubes (CNTs) under an electric field is investigated by molecular dynamics simulations. Due to the incompressibility and polarity of water, the mechanical property of CNTs can be tuned through filling with water molecules and applying an electric field. To explore the variation of the mechanical property of water-filled CNTs, the effects of the CNT length, the filling density and the electric field intensity are examined. The simulation results indicate that the water filling and electric field can result in a slight change in the elastic property (the elastic modulus and Poisson's ratio) of water-filled CNTs. However, the yield stress and average post-buckling stress exhibit a significant response to the water density and electric field intensity. As compared to hollow CNTs, the increment in yield stress of the water-filled CNTs under an electric field of 2.0 V Å-1 is up to 35.29%, which is even higher than that resulting from metal filling. The findings from this study provide a valuable theoretical basis for designing and fabricating the controlling units at the nanoscale.

Mechanical Behavior of BFRP-Steel Composite Plate under Axial Tension

Directory of Open Access Journals (Sweden)

Yunyu Li

2014-06-01

Full Text Available Combining the advantages of basalt fiber-reinforced polymer (BFRP material and steel material, a novel BFRP-steel composite plate (BSP is proposed, where a steel plate is sandwiched between two outer BFRP laminates. The main purpose of this research is to investigate the mechanical behavior of the proposed BSP under uniaxial tension and cyclic tension. Four groups of BSP specimens with four different BFRP layers and one control group of steel plate specimens were prepared. A uniaxial tensile test and a cyclic tensile test were conducted to determine the initial elastic modulus, postyield stiffness, yield strength, ultimate bearing capacity and residual deformation. Test results indicated that the stress-strain curve of the BSP specimen was bilinear prior to the fracture of the outer BFRP, and the BSP specimen had stable postyield stiffness and small residual deformation after the yielding of the inner steel plate. The postyield modulus of BSP specimens increased almost linearly with the increasing number of outer BFRP layers, as well as the ultimate bearing capacity. Moreover, the predicted results from the selected models under both monotonic tension and cyclic tension were in good agreement with the experimental data.

Fatigue degradation and failure of rotating composite structures - Materials characterisation and underlying mechanisms

Energy Technology Data Exchange (ETDEWEB)

Gamstedt, E K; Andersen, S I

2001-03-01

The present review concerns rotating composite structures, in which fatigue degradation is of key concern for in-service failure. Such applications are for instance rotor blades in wind turbines, helicopter rotor blades, flywheels for energy storage, marine and aeronautical propellers, and rolls for paper machines. The purpose is to identify areas where impending efforts should be made to make better use of composite materials in these applications. In order to obtain better design methodologies, which would allow more reliable and slender structures, improved test methods are necessary. Furthermore, the relation between structural, component and specimen test results should be better understood than what is presently the case. Improved predictive methods rely on a better understanding of the underlying damage mechanisms. With mechanism-based models, the component substructure or even the material microstructure could be optimised for best possible fatigue resistance. These issues are addressed in the present report, with special emphasis on test methods, and scaling from damage mechanisms to relevant material properties. (au)

Mechanisms underlying the effects of prenatal psychosocial stress on child outcomes: beyond the HPA axis

NARCIS (Netherlands)

Beijers, R.; Buitelaar, J.K.; Weerth, C. de

2014-01-01

Accumulating evidence from preclinical and clinical studies indicates that maternal psychosocial stress and anxiety during pregnancy adversely affect child outcomes. However, knowledge on the possible mechanisms underlying these relations is limited. In the present paper, we review the most often

Fatigue behaviour of the austenitic steel 1.4550 under mechanical and thermal cyclic loading

Energy Technology Data Exchange (ETDEWEB)

Siegele, D.; Fingerhuth, J.; Varfolomeev, I.; Moroz, S. [Fraunhofer Institute for Mechanics of Materials (IWM), Freiburg (Germany)

2014-07-01

Fatigue behaviour of the austenitic steel 1.4550 (X6CrNiNb18-10) under low-cycle fatigue and high-cycle thermal fatigue was investigated with in two research projects supported by the Federal Ministry of Economic Affairs and Energy and the Ministry of Education and Research. The objectives of the projects were the gain of deep understanding of the damage mechanisms under mechanical and thermal cyclic loading and the development of material models and simulation procedures for an improved lifetime assessment. In comparison to the advanced mechanism based material models engineering computational procedures were proven with respect to their applicability and conservatisms. For thermal cyclic loading, test equipment and technique were developed which allow for cyclic thermal loading with temperature ranges between 1 00 C and 300 C and frequencies between 0.1 and 1 Hz. As a result, tests with a temperature range of 150 C and lower showed no crack formation up to 300,000 cycles. For temperature ranges of 200 C and higher multiple crack patterns were observed with the deepest crack of about 1.3 mm after 1,000,000 cycles, whereas the difference in crack depth between 300,000 and 1,000,000 cycles was negligibly small. To model the fatigue lifetime, the D{sub TMF} damage parameter was applied to the low-cycle fatigue and the thermal, high frequent fatigue tests. For thermal fatigue, the analyses predicted in agreement with the tests crack initiation followed by crack propagation, subsequent retardation and arrest. This behaviour can be explained qualitatively and quantitatively using the methods of linear-elastic fracture mechanics, whereas the consideration of the interaction of multiple cracks is essential to describe the experimentally observed crack retardation. The results for thermal fatigue are in the scatterband of the mechanical p and thermo-mechanical fatigue results and the cycles to failure are 10 times higher than those estimated according to the KTA fatigue

Statistical model for the mechanical behavior of the tissue engineering non-woven fibrous matrices under large deformation.

Science.gov (United States)

Rizvi, Mohd Suhail; Pal, Anupam

2014-09-01

The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues due to their structural and mechanical similarities with the fibrous components of the extracellular matrix. These scaffolds not only provide the appropriate microenvironment for the residing cells but also act as medium for the transmission of the mechanical stimuli, essential for the tissue regeneration, from macroscopic scale of the scaffolds to the microscopic scale of cells. The requirement of the mechanical loading for the tissue regeneration requires the fibrous scaffolds to be able to sustain the complex three-dimensional mechanical loading conditions. In order to gain insight into the mechanical behavior of the fibrous matrices under large amount of elongation as well as shear, a statistical model has been formulated to study the macroscopic mechanical behavior of the electrospun fibrous matrix and the transmission of the mechanical stimuli from scaffolds to the cells via the constituting fibers. The study establishes the load-deformation relationships for the fibrous matrices for different structural parameters. It also quantifies the changes in the fiber arrangement and tension generated in the fibers with the deformation of the matrix. The model reveals that the tension generated in the fibers on matrix deformation is not homogeneous and hence the cells located in different regions of the fibrous scaffold might experience different mechanical stimuli. The mechanical response of fibrous matrices was also found to be dependent on the aspect ratio of the matrix. Therefore, the model establishes a structure-mechanics interdependence of the fibrous matrices under large deformation, which can be utilized in identifying the appropriate structure and external mechanical loading conditions for the regeneration of load-bearing tissues. Copyright © 2014 Elsevier Ltd. All rights reserved.

Growth of 2D and 3D plane cracks under thermo-mechanical loading with varying amplitudes

International Nuclear Information System (INIS)

Sbitti, Amine

2009-01-01

After a presentation of the phenomenon of thermal fatigue (in industrial applications and nuclear plants), this research thesis reports the investigation of the growth and arrest of a 2D crack under thermal fatigue (temperature and stress distribution over thickness, calculation of stress intensity factors, laws of fatigue crack growth, growth under varying amplitude), and the investigation of 3D crack growth under cyclic loading with varying amplitudes (analytic and numerical calculation of stress intensity factors, variational formulation in failure mechanics, 3D crack propagation under fatigue, use of the Aster code, use of the extended finite element method or X-FEM). The author discusses the origin and influence of the 3D crack network under thermal fatigue

Theoretical modeling of mechanical homeostasis of a mammalian cell under gravity-directed vector.

Science.gov (United States)

Zhou, Lüwen; Zhang, Chen; Zhang, Fan; Lü, Shouqin; Sun, Shujin; Lü, Dongyuan; Long, Mian

2018-02-01

Translocation of dense nucleus along gravity vector initiates mechanical remodeling of a eukaryotic cell. In our previous experiments, we quantified the impact of gravity vector on cell remodeling by placing an MC3T3-E1 cell onto upward (U)-, downward (D)-, or edge-on (E)- orientated substrate. Our experimental data demonstrate that orientation dependence of nucleus longitudinal translocation is positively correlated with cytoskeletal (CSK) remodeling of their expressions and structures and also is associated with rearrangement of focal adhesion complex (FAC). However, the underlying mechanism how CSK network and FACs are reorganized in a mammalian cell remains unclear. In this paper, we developed a theoretical biomechanical model to integrate the mechanosensing of nucleus translocation with CSK remodeling and FAC reorganization induced by a gravity vector. The cell was simplified as a nucleated tensegrity structure in the model. The cell and CSK filaments were considered to be symmetrical. All elements of CSK filaments and cytomembrane that support the nucleus were simplified as springs. FACs were simplified as an adhesion cluster of parallel bonds with shared force. Our model proposed that gravity vector-directed translocation of the cell nucleus is mechanically balanced by CSK remodeling and FAC reorganization induced by a gravitational force. Under gravity, dense nucleus tends to translocate and exert additional compressive or stretching force on the cytoskeleton. Finally, changes of the tension force acting on talin by microfilament alter the size of FACs. Results from our model are in qualitative agreement with those from experiments.

Vascular Adventitia Calcification and Its Underlying Mechanism.

Directory of Open Access Journals (Sweden)

Na Li

Full Text Available Previous research on vascular calcification has mainly focused on the vascular intima and media. However, we show here that vascular calcification may also occur in the adventitia. The purpose of this work is to help elucidate the pathogenic mechanisms underlying vascular calcification. The calcified lesions were examined by Von Kossa staining in ApoE-/- mice which were fed high fat diets (HFD for 48 weeks and human subjects aged 60 years and older that had died of coronary heart disease, heart failure or acute renal failure. Explant cultured fibroblasts and smooth muscle cells (SMCswere obtained from rat adventitia and media, respectively. After calcification induction, cells were collected for Alizarin Red S staining. Calcified lesions were observed in the aorta adventitia and coronary artery adventitia of ApoE-/-mice, as well as in the aorta adventitia of human subjects examined. Explant culture of fibroblasts, the primary cell type comprising the adventitia, was successfully induced for calcification after incubation with TGF-β1 (20 ng/ml + mineralization media for 4 days, and the phenotype conversion vascular adventitia fibroblasts into myofibroblasts was identified. Culture of SMCs, which comprise only a small percentage of all cells in the adventitia, in calcifying medium for 14 days resulted in significant calcification.Vascular calcification can occur in the adventitia. Adventitia calcification may arise from the fibroblasts which were transformed into myofibroblasts or smooth muscle cells.

Resveratrol increases nucleus pulposus matrix synthesis through activating the PI3K/Akt signaling pathway under mechanical compression in a disc organ culture.

Science.gov (United States)

Han, Xiaorui; Leng, Xiaoming; Zhao, Man; Wu, Mei; Chen, Amei; Hong, Guoju; Sun, Ping

2017-12-22

Disc nucleus pulposus (NP) matrix homeostasis is important for normal disc function. Mechanical overloading seriously decreases matrix synthesis and increases matrix degradation. The present study aims to investigate the effects of resveratrol on disc NP matrix homeostasis under a relatively high-magnitude mechanical compression and the potential mechanism underlying this process. Porcine discs were perfusion-cultured and subjected to a relatively high-magnitude mechanical compression (1.3 MPa at a frequency of 1.0 Hz for 2 h once per day) for 7 days in a mechanically active bioreactor. The non-compressed discs were used as controls. Resveratrol was added along with culture medium to observe the effects of resveratrol on NP matrix synthesis under mechanical load respectively. NP matrix synthesis was evaluated by histology, biochemical content (glycosaminoglycan (GAG) and hydroxyproline (HYP)), and expression of matrix macromolecules (aggrecan and collagen II). Results showed that this high-magnitude mechanical compression significantly decreased NP matrix content, indicated by the decreased staining intensity of Alcian Blue and biochemical content (GAG and HYP), and the down-regulated expression of NP matrix macromolecules (aggrecan and collagen II). Further analysis indicated that resveratrol partly stimulated NP matrix synthesis and increased activity of the PI3K/Akt pathway in a dose-dependent manner under mechanical compression. Together, resveratrol is beneficial for disc NP matrix synthesis under mechanical overloading, and the activation of the PI3K/Akt pathway may participate in this regulatory process. Resveratrol may be promising to regenerate mechanical overloading-induced disc degeneration. © 2017 The Author(s).

A prospective, observational, epidemiological evaluation of the aetiology and antimicrobial susceptibility of acute otitis media in Saudi children younger than 5years of age.

Science.gov (United States)

Al-Mazrou, Khalid A; Shibl, Atef M; Kandeil, Walid; Pirçon, Jean-Yves; Marano, Cinzia

2014-09-01

Information regarding acute otitis media (AOM) aetiology is important for developing effective vaccines. Here, bacterial aetiology and antimicrobial susceptibility of AOM were determined in young Saudi children. Children aged 3-60months with a new episode of AOM, who had not received antibiotics or had received antibiotics for 48-72h but remained symptomatic, were enrolled in this prospective, observational, epidemiological study in Riyadh. Middle ear fluid (MEF) samples were collected by tympanocentesis or from spontaneous otorrhea, and tested for the presence of Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes and Moraxella catarrhalis. Antimicrobial susceptibility of the identified pathogens was assessed using E-tests. Between June 2009 and May 2011, 66 children were enrolled. S. pneumoniae was detected in 6 episodes and non-typeable H. influenzae (NTHi) in 8 episodes. Moreover, Staphylococcus aureus, which is an uncommon cause of AOM, was detected in 17 episodes. Pneumococcal serotypes were 7F (n=2), 23F (n=2), 19F (n=1) and 15F (n=1). Susceptibility to cefotaxime was observed in all pneumococcal and H. influenzae isolates, to cefuroxime in 4/6 pneumococcal and 8/8 H. influenzae isolates, and to penicillin in 5/6 pneumococcal isolates. S. pneumoniae and NTHi were major bacterial contributors for AOM in Saudi children. Copyright © 2014. Published by Elsevier Ltd.

Scientific conception on mechanisms of calcium homeostasis disorders under low dose effect of ionizing radiation

International Nuclear Information System (INIS)

Abylaev, Zh.A.; Dospolova, Zh.G.

1997-01-01

Scientific conception of probable consequences of calcium homeostasis disorders in personals, exposed to low dose effect of ionizing radiation has been developed. Principle positions of the conception is that pathologic processes development have different ways of conducting. During predominance of low doses of external gamma-radiation there is leading pathologic mechanism (mechanism 1) of disorder neuroendocrine regulation of both the calcium and the phosphor. In this case sicks have disorders of both the vegetative tonus and the endocrine status. Under internal irradiation (mechanism 2) there is disfunction of organs and systems (bore changes and disorders of hormone status). These changes are considered as consequence of negative action on organism of incorporated long-living radionuclides. Radio-toxic factors action (mechanism 3) provokes the excess of hormones, which acting on bone tissue and could be cause of steroid osteoporosis. Influence of chronic stress factor (mechanism 4) enlarges and burden action on organism of low radiation doses. It is emphasized, that decisive role in development of pathologic processes has mechanism of disturbance of neuroendocrine regulation of calcium exchange

Microstructural development under interrupted hot deformation and the mechanical properties of a cast Mg–Gd–Y–Zr alloy

Energy Technology Data Exchange (ETDEWEB)

Xiao, Zhenyu [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yang, Xuyue [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Institute for Materials Microstructure, Central South University, Changsha 410083 (China); Yang, Yi; Zhang, Zhirou; Zhang, Duxiu; Li, Yi [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Sakai, Taku [UEC Tokyo (The University of Electro-Communications), Chofu, Tokyo 182-8585 (Japan)

2016-01-15

Microstructural development under interrupted hot deformation of a cast Mg–Gd–Y–Zr alloy was investigated by optical microscopy (OM) and electron backscattering diffraction (EBSD) technology and the resultant mechanical properties were detected through tensile tests at room temperature. Ultrafine grains (UFGs) were remarkably developed under the condition of interrupted hot forging, resulting in an improvement of ambient mechanical properties. The basal texture was weakened by an effective increase of the volume fraction of UFGs under interrupted hot forging. These resulted in an improvement of tensile ductility with little or no drop in strength, i.e. the volume fraction of UFGs was raised from 30% to 70%, leading to an increase of the ambient tensile elongation from 15% to 23%.

Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms.

Science.gov (United States)

Vidal-Dupiol, Jeremie; Adjeroud, Mehdi; Roger, Emmanuel; Foure, Laurent; Duval, David; Mone, Yves; Ferrier-Pages, Christine; Tambutte, Eric; Tambutte, Sylvie; Zoccola, Didier; Allemand, Denis; Mitta, Guillaume

2009-08-04

Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28 degrees C to 32 degrees C over 15 days. A second control set kept at constant temperature (28 degrees C). The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching) and the non stressed states (control) were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function) were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin) contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich). Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress. Under thermal stress

Fracture mechanics in new designed power module under thermo-mechanical loads

Directory of Open Access Journals (Sweden)

Durand Camille

2014-06-01

Full Text Available Thermo-mechanically induced failure is a major reliability issue in the microelectronic industry. On this account, a new type of Assembly Interconnected Technology used to connect MOSFETs in power modules has been developed. The reliability is increased by using a copper clip soldered on the top side of the chip, avoiding the use of aluminium wire bonds, often responsible for the failure of the device. Thus the new designed MOSFET package does not follow the same failure mechanisms as standard modules. Thermal and power cycling tests were performed on these new packages and resulting failures were analyzed. Thermo-mechanical simulations including cracks in the aluminium metallization and intermetallics (IMC were performed using Finite Element Analysis in order to better understand crack propagation and module behaviour.

A coupled diffusion-fluid pressure model to predict cell density distribution for cells encapsulated in a porous hydrogel scaffold under mechanical loading.

Science.gov (United States)

Zhao, Feihu; Vaughan, Ted J; Mc Garrigle, Myles J; McNamara, Laoise M

2017-10-01

Tissue formation within tissue engineering (TE) scaffolds is preceded by growth of the cells throughout the scaffold volume and attachment of cells to the scaffold substrate. It is known that mechanical stimulation, in the form of fluid perfusion or mechanical strain, enhances cell differentiation and overall tissue formation. However, due to the complex multi-physics environment of cells within TE scaffolds, cell transport under mechanical stimulation is not fully understood. Therefore, in this study, we have developed a coupled multiphysics model to predict cell density distribution in a TE scaffold. In this model, cell transport is modelled as a thermal conduction process, which is driven by the pore fluid pressure under applied loading. As a case study, the model is investigated to predict the cell density patterns of pre-osteoblasts MC3T3-e1 cells under a range of different loading regimes, to obtain an understanding of desirable mechanical stimulation that will enhance cell density distribution within TE scaffolds. The results of this study have demonstrated that fluid perfusion can result in a higher cell density in the scaffold region closed to the outlet, while cell density distribution under mechanical compression was similar with static condition. More importantly, the study provides a novel computational approach to predict cell distribution in TE scaffolds under mechanical loading. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pluripotent Stem Cell Studies Elucidate the Underlying Mechanisms of Early Embryonic Development

Directory of Open Access Journals (Sweden)

Lingyu Li

2011-03-01

Full Text Available Early embryonic development is a multi-step process that is intensively regulated by various signaling pathways. Because of the complexity of the embryo and the interactions between the germ layers, it is very difficult to fully understand how these signals regulate embryo patterning. Recently, pluripotent stem cell lines derived from different developmental stages have provided an in vitro system for investigating molecular mechanisms regulating cell fate decisions. In this review, we summarize the major functions of the BMP, FGF, Nodal and Wnt signaling pathways, which have well-established roles in vertebrate embryogenesis. Then, we highlight recent studies in pluripotent stem cells that have revealed the stage-specific roles of BMP，FGF and Nodal pathways during neural differentiation. These findings enhance our understanding of the stepwise regulation of embryo patterning by particular signaling pathways and provide new insight into the mechanisms underlying early embryonic development.

Thermo-Mechanical Properties of Semi-Degradable Poly(β-amino ester)-co-Methyl Methacrylate Networks under Simulated Physiological Conditions

Science.gov (United States)

Safranski, David L.; Crabtree, Jacob C.; Huq, Yameen R.; Gall, Ken

2011-01-01

Poly(β-amino ester) networks are being explored for biomedical applications, but they may lack the mechanical properties necessary for long term implantation. The objective of this study is to evaluate the effect of adding methyl methacrylate on networks' mechanical properties under simulated physiological conditions. The networks were synthesized in two parts: (1) a biodegradable crosslinker was formed from a diacrylate and amine, (2) and then varying concentrations of methyl methacrylate were added prior to photopolymerizing the network. Degradation rate, mechanical properties, and glass transition temperature were studied as a function of methyl methacrylate composition. The crosslinking density played a limited role on mechanical properties for these networks, but increasing methyl methacrylate concentration improved the toughness by several orders of magnitude. Under simulated physiological conditions, networks showed increasing toughness or sustained toughness as degradation occurred. This work establishes a method of creating degradable networks with tailorable toughness while undergoing partial degradation. PMID:21966028

Statistical mechanics of fluids under internal constraints: Rigorous results for the one-dimensional hard rod fluid

International Nuclear Information System (INIS)

Corti, D.S.; Debenedetti, P.G.

1998-01-01

The rigorous statistical mechanics of metastability requires the imposition of internal constraints that prevent access to regions of phase space corresponding to inhomogeneous states. We derive exactly the Helmholtz energy and equation of state of the one-dimensional hard rod fluid under the influence of an internal constraint that places an upper bound on the distance between nearest-neighbor rods. This type of constraint is relevant to the suppression of boiling in a superheated liquid. We determine the effects of this constraint upon the thermophysical properties and internal structure of the hard rod fluid. By adding an infinitely weak and infinitely long-ranged attractive potential to the hard core, the fluid exhibits a first-order vapor-liquid transition. We determine exactly the equation of state of the one-dimensional superheated liquid and show that it exhibits metastable phase equilibrium. We also derive statistical mechanical relations for the equation of state of a fluid under the action of arbitrary constraints, and show the connection between the statistical mechanics of constrained and unconstrained ensembles. copyright 1998 The American Physical Society

Corporate debts ad credit performance under the new mechanism of reorganization of the Russian banks

Directory of Open Access Journals (Sweden)

Sergey A. Andryushin

2017-09-01

Full Text Available Objective to explore the dynamics and factors of formation of corporate debts the characteristics of low credit activity of the Russian banks and regulation of liquidity deficit of enterprises under the new reorganization mechanism in the Russian banking sector. Methods systematic approach to the cognition of economic phenomena which allows to study them in their dynamic development taking into account the influence of various environmental factors. The systematic approach determined selection of specific research methods empirical logical comparative and statistical. Results the article is devoted to the problems of declining credit activity of commercial banks under the conditions of economic activity revival as well as to assessing the impact of the new reorganization mechanism on this process. It is shown that in the recent years the nonfinancial sector faces the trend of optimizing the corporate debts and the liquidity deficit which reduced the demand for loans and as a consequence decreased the banksrsquo credit activity. To analyze the dynamics of deficitsurplus of liquidity in the corporate sector a new classification of liquidity deficitsurplus levels was introduced. Based on the proposed classification the risk factors were identified that influenced the dynamics of indebtedness in the corporate sector. The article also analyses the modern monetary mechanism of money supply in the economy and its transformation. It was determined that the main limitation of credit issuance by commercial banks is their capital not the reserve multiplier. The new mechanism of credit institutionsrsquo financial recovery and its impact on the banksrsquo credit activity was estimated. The conditions of liquidity deficiency reduction in the Russian companies were analyzed in the medium term. Scientific novelty for the first time on the basis of system analysis methods the growth factors of the corporate debt load were identified the peculiarities of low

Different neurophysiological mechanisms underlying word and rule extraction from speech.

Directory of Open Access Journals (Sweden)

Ruth De Diego Balaguer

Full Text Available The initial process of identifying words from spoken language and the detection of more subtle regularities underlying their structure are mandatory processes for language acquisition. Little is known about the cognitive mechanisms that allow us to extract these two types of information and their specific time-course of acquisition following initial contact with a new language. We report time-related electrophysiological changes that occurred while participants learned an artificial language. These changes strongly correlated with the discovery of the structural rules embedded in the words. These changes were clearly different from those related to word learning and occurred during the first minutes of exposition. There is a functional distinction in the nature of the electrophysiological signals during acquisition: an increase in negativity (N400 in the central electrodes is related to word-learning and development of a frontal positivity (P2 is related to rule-learning. In addition, the results of an online implicit and a post-learning test indicate that, once the rules of the language have been acquired, new words following the rule are processed as words of the language. By contrast, new words violating the rule induce syntax-related electrophysiological responses when inserted online in the stream (an early frontal negativity followed by a late posterior positivity and clear lexical effects when presented in isolation (N400 modulation. The present study provides direct evidence suggesting that the mechanisms to extract words and structural dependencies from continuous speech are functionally segregated. When these mechanisms are engaged, the electrophysiological marker associated with rule-learning appears very quickly, during the earliest phases of exposition to a new language.

Supersymmetric quantum mechanics under point singularities

International Nuclear Information System (INIS)

Uchino, Takashi; Tsutsui, Izumi

2003-01-01

We provide a systematic study on the possibility of supersymmetry (SUSY) for one-dimensional quantum mechanical systems consisting of a pair of lines R or intervals [-l, l] each having a point singularity. We consider the most general singularities and walls (boundaries) at x = ±l admitted quantum mechanically, using a U(2) family of parameters to specify one singularity and similarly a U(1) family of parameters to specify one wall. With these parameter freedoms, we find that for a certain subfamily the line systems acquire an N = 1 SUSY which can be enhanced to N = 4 if the parameters are further tuned, and that these SUSY are generically broken except for a special case. The interval systems, on the other hand, can accommodate N = 2 or N = 4 SUSY, broken or unbroken, and exhibit a rich variety of (degenerate) spectra. Our SUSY systems include the familiar SUSY systems with the Dirac δ(x)-potential, and hence are extensions of the known SUSY quantum mechanics to those with general point singularities and walls. The self-adjointness of the supercharge in relation to the self-adjointness of the Hamiltonian is also discussed

Aetiological influences on stability and change in emotional and behavioural problems across development: a systematic review.

Science.gov (United States)

Hannigan, L J; Walaker, N; Waszczuk, M A; McAdams, T A; Eley, T C

2017-01-01

Emotional and behavioural problems in childhood and adolescence can be chronic and are predictive of future psychiatric problems. Understanding what factors drive the development and maintenance of these problems is therefore crucial. Longitudinal behavioural genetic studies using twin, sibling or adoption data can be used to explore the developmental aetiology of stability and change in childhood and adolescent psychopathology. We present a systematic review of longitudinal, behavioural genetic analyses of emotional and behavioural problems between ages 0 to 18 years. We identified 58 studies, of which 19 examined emotional problems, 30 examined behavioural problems, and 9 examined both. In the majority of studies, stability in emotional and behavioural problems was primarily genetically influenced. Stable environmental factors were also widely found, although these typically played a smaller role. Both genetic and environmental factors were involved in change across development. We discuss the findings in the context of the wider developmental literature and make recommendations for future research.

Experimental study on the thermo-mechanical behaviour of stiff clay under non-isotropic stress state

International Nuclear Information System (INIS)

Tang, Anh Minh; Cui, Yu-Jun; Li, Xiang-Ling

2012-01-01

Document available in extended abstract form only. Stiff clay is usually considered as possible host-rock for geological radioactive waste disposal due to its low permeability and its self-sealing capacity. Boom Clay, for instance, is one of the clays currently considered by the Belgian radioactive waste management agency Ondraf/Niras as a potential host for a geological repository. In order to analyse the performance of this material, it is important to understand its behaviour under the coupled thermo-hydro-mechanical solicitations. In laboratory, several studies have been performed to study the volume change of clay under coupled thermomechanical loading. The results show that heating under drained conditions can induce thermal dilation at low confining stress and thermal contraction at high confining stress. On the other hand, compression tests performed at constant temperature show that the compressibility parameters of soil can be modified by temperature change. These features are now well considered in constitutive laws based on the framework of elasto-plasticity. Under undrained conditions, heating can increase pore-water pressure and this behaviour can be simulated using the theoretical thermo-poro-elastic framework. The temperature effect on the soil behaviour under triaxial compression is also often considered. It is commonly accepted that heating decreases the shear strength of clay but this softening can be hidden by the thermal contraction that occurs during heating which can induce at the same time soil hardening. In spite of these existing works, laboratory tests considering the thermo-mechanical loading path that the soil can be subjected to are still rare. Actually, in the case of geological radioactive waste disposal, after the installation of waste canisters, the soil is expected to be heated under non-isotropic stress state. Most of the existing laboratory works show heating tests in odometer cell or triaxial cell under isotropic stress

Push-and-stick mechanism for charged and excited small cluster emission under ion bombardment

International Nuclear Information System (INIS)

Bitensky, I.S.; Parilis, E.S.; Wojciechowski, I.A.

1992-01-01

The mechanism for the formation, excitation and ionization of small clusters emitted under ion bombardment is discussed. It is shown that the increased degree of ionization for the transition metal dimers, trimers and tetramers can be explained by the existence of an additional effective channel for their formation, namely the associative ionization process. A simple estimate shows that the sticking together of a fast cascade atom and the pushed out surface atom is 30-40 times more effective for dimer formation, than the recombination of two fast atoms. This push-and-stick mechanism of cluster formation could also be effective for the formation of trimers and tetramers. (orig.)

Surviving a Dry Future: Abscisic Acid (ABA)-Mediated Plant Mechanisms for Conserving Water under Low Humidity

Science.gov (United States)

McAdam, Scott A. M.

2017-01-01

Angiosperms are able to respond rapidly to the first sign of dry conditions, a decrease in air humidity, more accurately described as an increase in the vapor pressure deficit between the leaf and the atmosphere (VPD), by abscisic acid (ABA)-mediated stomatal closure. The genes underlying this response offer valuable candidates for targeted selection of crop varieties with improved drought tolerance, a critical goal for current plant breeding programs, to maximize crop production in drier and increasingly marginalized environments, and meet the demands of a growing population in the face of a changing climate. Here, we review current understanding of the genetic mechanisms underpinning ABA-mediated stomatal closure, a key means for conserving water under dry conditions, examine how these mechanisms evolved, and discuss what remains to be investigated. PMID:29113039

Complex regional pain syndrome (CRPS) impairs visuospatial perception,whereas post-herpetic neuralgia does not: possible implications for supraspinal mechanism of CRPS.

Science.gov (United States)

Uematsu, Hironobu; Sumitani, Masahiko; Yozu, Arito; Otake, Yuko; Shibata, Masahiko; Mashimo, Takashi; Miyauchi, Satoru

2009-11-01

Complex regional pain syndrome (CRPS) patients show impaired visuospatial perception in the dark, as compared to normal patients with acute nociceptive pain. The purpose of this study is 2-fold: (i) to ascertain whether this distorted visuospatial perception is related to the chronicity of pain, and (ii) to analyse visuospatial perception of CRPS in comparison with another neuropathic pain condition. We evaluated visual subjective body-midline (vSM) representation in 27 patients with post-herpetic neuralgia (PHN) and 22 with CRPS under light and dark conditions. A red laser dot was projected onto a screen and moved horizontally towards the sagittal plane of the objective body-midline (OM). Each participant was asked to direct the dot to a position where it crossed their vSM. The distance between the vSM and OM was analysed to determine how and in which direction the vSM deviated. Under light condition, all vSM judgments approximately matched the OM. However, in the dark, CRPS patients, but not PHN patients, showed a shifted vSM towards the affected side. We demonstrated that chronic pain does not always impair visuospatial perception. The aetiology of PHN is limited to the peripheral nervous system, whereas the distorted visuospatial perception suggests a supraspinal aetiology of CRPS.

A micromechanical study of the damage mechanics of acrylic particulate composites under thermomechanical loading

Science.gov (United States)

Nie, Shihua

The main aim of this dissertation was to characterize the damage mechanism and fatigue behavior of the acrylic particulate composite. This dissertation also investigated how the failure mechanism is influenced by changes in certain parameters including the volume fraction of particle, the interfacial bonding strength, the stiffness and thickness of the interphase, and the CTE mismatch between the particle and the matrix. Monotonic uniaxial tensile and compressive testing under various temperatures and strain rates, isothermal low-cycle mechanical testing and thermal cycling of a plate with a cutout were performed. The influence of the interfacial bonding strength between the particle and the matrix on the failure mechanism of the ATH filled PMMA was investigated using in situ observations under uniaxial loading conditions. For composites with weak interfacial bonding, the debonding is the major damage mode. For composites with strong interfacial bonding, the breakage of the agglomerate of particles is the major damage mode. Experimental studies also demonstrated the significant influence of interfacial bonding strength on the fatigue life of the ATH filled PMMA. The damage was characterized in terms of the elastic modulus degradation, the load-drop parameter, the plastic strain range and the hysteresis dissipation. Identifying the internal state variables that quantify material degradation under thermomechanical loading is an active research field. In this dissertation, the entropy production, which is a measure of the irreversibility of the thermodynamic system, is used as the metric for damage. The close correlation between the damage measured in terms of elastic modulus degradation and that obtained from the finite element simulation results validates the entropy based damage evolution function. A micromechanical model for acrylic particulate composites with imperfect interfacial bonds was proposed. Acrylic particulate composites are treated as three

Mechanical and Thermophysical Properties of Cubic Rock-Salt AlN Under High Pressure

Science.gov (United States)

Lebga, Noudjoud; Daoud, Salah; Sun, Xiao-Wei; Bioud, Nadhira; Latreche, Abdelhakim

2018-03-01

Density functional theory, density functional perturbation theory, and the Debye model have been used to investigate the structural, elastic, sound velocity, and thermodynamic properties of AlN with cubic rock-salt structure under high pressure, yielding the equilibrium structural parameters, equation of state, and elastic constants of this interesting material. The isotropic shear modulus, Pugh ratio, and Poisson's ratio were also investigated carefully. In addition, the longitudinal, transverse, and average elastic wave velocities, phonon contribution to the thermal conductivity, and interesting thermodynamic properties were predicted and analyzed in detail. The results demonstrate that the behavior of the elastic wave velocities under increasing hydrostatic pressure explains the hardening of the corresponding phonons. Based on the elastic stability criteria under pressure, it is found that AlN with cubic rock-salt structure is mechanically stable, even at pressures up to 100 GPa. Analysis of the Pugh ratio and Poisson's ratio revealed that AlN with cubic rock-salt structure behaves in brittle manner.

The relationship of transverse sinus stenosis to bony groove dimensions provides an insight into the aetiology of idiopathic intracranial hypertension

Energy Technology Data Exchange (ETDEWEB)

Connor, S.E.J.; Stewart, V.R.; O' Flynn, E.A.M. [King' s College Hospital, Neuroradiology Department, Ruskin Wing, London (United Kingdom); Siddiqui, M.A. [Southern General Hospital, Institute of Neurological Sciences, Glasgow (United Kingdom)

2008-12-15

Transverse sinus tapered narrowings are frequently identified in patients with idiopathic intracranial hypertension (IIH); however, it remains unclear whether they are primary stenoses or whether they occur secondary to raised cerebrospinal fluid pressure. Computed tomographic venography demonstrates both the morphology of the venous system and the adjacent bony grooves so it may provide an insight into the aetiology of these transverse sinus stenoses. Tapered transverse sinus narrowings (>50%) were studied in 19 patients without IIH and 14 patients with IIH. Computed tomography vascular studies were reviewed and the dimensions of the venous sinuses and bony grooves at the sites of maximum and minimum transverse sinus area dimensions were recorded. There was demonstrated to be a strong correlation of bony groove height with venous sinus height at the largest portions of the transverse sinus in both IIH patients and non-IIH subjects as well as at the transverse sinus narrowing in non-IIH subjects. There was a discordant relationship between bony groove height and venous sinus height at the site of transverse sinus stenoses in IIH patients. In 5/23 IIH transverse sinus stenoses, the bony groove height was proportionate to that seen in non-IIH subjects. There were a further 8/23 cases where the small or absent sinus was associated with an absent bony groove. Transverse sinus tapered narrowings in subjects without IIH and in the majority of patients with IIH were associated with proportionately small or absent grooves, and these are postulated to be primary or fixed. Some patients with IIH demonstrate tapered transverse sinus stenoses with disproportionately large bony grooves, suggesting a secondary or acquired narrowing. This implies a varied aetiology for the transverse sinus stenoses of IIH. (orig.)

The relationship of transverse sinus stenosis to bony groove dimensions provides an insight into the aetiology of idiopathic intracranial hypertension

International Nuclear Information System (INIS)

Connor, S.E.J.; Stewart, V.R.; O'Flynn, E.A.M.; Siddiqui, M.A.

2008-01-01

Transverse sinus tapered narrowings are frequently identified in patients with idiopathic intracranial hypertension (IIH); however, it remains unclear whether they are primary stenoses or whether they occur secondary to raised cerebrospinal fluid pressure. Computed tomographic venography demonstrates both the morphology of the venous system and the adjacent bony grooves so it may provide an insight into the aetiology of these transverse sinus stenoses. Tapered transverse sinus narrowings (>50%) were studied in 19 patients without IIH and 14 patients with IIH. Computed tomography vascular studies were reviewed and the dimensions of the venous sinuses and bony grooves at the sites of maximum and minimum transverse sinus area dimensions were recorded. There was demonstrated to be a strong correlation of bony groove height with venous sinus height at the largest portions of the transverse sinus in both IIH patients and non-IIH subjects as well as at the transverse sinus narrowing in non-IIH subjects. There was a discordant relationship between bony groove height and venous sinus height at the site of transverse sinus stenoses in IIH patients. In 5/23 IIH transverse sinus stenoses, the bony groove height was proportionate to that seen in non-IIH subjects. There were a further 8/23 cases where the small or absent sinus was associated with an absent bony groove. Transverse sinus tapered narrowings in subjects without IIH and in the majority of patients with IIH were associated with proportionately small or absent grooves, and these are postulated to be primary or fixed. Some patients with IIH demonstrate tapered transverse sinus stenoses with disproportionately large bony grooves, suggesting a secondary or acquired narrowing. This implies a varied aetiology for the transverse sinus stenoses of IIH. (orig.)

The Mechanical Behaviors of Various Dental Implant Materials under Fatigue

Directory of Open Access Journals (Sweden)

Fatma Bayata

2018-01-01

Full Text Available The selection of materials has a considerable role on long-term stability of implants. The materials having high resistance to fatigue are required for dental implant applications since these implants are subjected to cyclic loads during chewing. This study evaluates the performance of different types of materials (AISI 316L stainless steel, alumina and its porous state, CoCr alloys, yttrium-stabilized zirconia (YSZ, zirconia-toughened alumina (ZTA, and cp Ti with the nanotubular TiO2 surface by finite element analysis (FEA under real cyclic biting loads and researches the optimum material for implant applications. For the analysis, the implant design generated by our group was utilized. The mechanical behavior and the life of the implant under biting loads were estimated based on the material and surface properties. According to the condition based on ISO 14801, the FEA results showed that the equivalent von Mises stress values were in the range of 226.95 MPa and 239.05 MPa. The penetration analysis was also performed, and the calculated penetration of the models onto the bone structure ranged between 0.0037389 mm and 0.013626 mm. L-605 CoCr alloy-assigned implant model showed the least penetration, while cp Ti with the nanotubular TiO2 surface led to the most one. However, the difference was about 0.01 mm, and it may not be evaluated as a distinct difference. As the final numerical evaluation item, the fatigue life was executed, and the results were achieved in the range of 4 × 105 and 1 × 109 cycles. These results indicated that different materials showed good performance for each evaluation component, but considering the overall mechanical performance and the treatment process (implant adsorption by means of surface properties, cp Ti with the nanotubular TiO2 surface material was evaluated as the suitable one, and it may also be implied that it displayed enough performance in the designed dental implant model.

Mechanism Underlying the Spatial Pattern Formation of Dominant Tree Species in a Natural Secondary Forest.

Directory of Open Access Journals (Sweden)

Guodong Jia

Full Text Available Studying the spatial pattern of plant species may provide significant insights into processes and mechanisms that maintain stand stability. To better understand the dynamics of naturally regenerated secondary forests, univariate and bivariate Ripley's L(r functions were employed to evaluate intra-/interspecific relationships of four dominant tree species (Populus davidiana, Betula platyphylla, Larix gmelinii and Acer mono and to distinguish the underlying mechanism of spatial distribution. The results showed that the distribution of soil, water and nutrients was not fragmented but presented clear gradients. An overall aggregated distribution existed at most distances. No correlation was found between the spatial pattern of soil conditions and that of trees. Both positive and negative intra- and interspecific relationships were found between different DBH classes at various distances. Large trees did not show systematic inhibition of the saplings. By contrast, the inhibition intensified as the height differences increased between the compared pairs. Except for Larix, universal inhibition of saplings by upper layer trees occurred among other species, and this reflected the vertical competition for light. Therefore, we believe that competition for light rather than soil nutrients underlies the mechanism driving the formation of stand spatial pattern in the rocky mountainous areas examined.

Failure mechanism of coated biomaterials under high impact-sliding contact stresses

Science.gov (United States)

Chen, Ying

This study uses a newly developed testing method--- inclined cyclic impact-sliding test to investigate the failure behaviors of different types of biomaterials, (SS316L, Ti6Al4V and CoCr) coated by different coatings (TiN, DLC and PEO), under extremely high dynamic contact stress conditions. This test method can simulate the combined impact and sliding/rolling loading conditions, which is very practical in many aspects of commercial usages. During the tests, fatigue cracking, chipping, peeling and material transferring were observed in damaged area. This research is mainly focused on the failure behaviors of load-bearing materials which cyclic impacting and sliding are always involved. This purpose was accomplished in the three stages: First, impact-sliding test was carried out on TiN coated unhardened M2. It was found that soft substrate can cause early failure of coating due to the considerable plastic deformation in the substrate. In this case, stronger substrate is required to support coating better when tested under high contact stresses. Second, PEO coated Ti-6Al-4V was tested under pure sliding and impact-sliding wear conditions. PEO coating was found not strong enough to afford the high contact pressure under cyclic impact-sliding wear test due to its porous surface structure. However, the wear performance of PEO coating was enhanced due to the sub-stoichiometric oxide. To sum up, for load-bearing biomedical implants involved in high impacting movement, PEO coating may not be a promising surface protection. Third, the dense, smooth PVD/CVD bio-inert coatings were reconsidered. DLC and TiN coatings, combined by different substrates together with different interface materials were tested under the cyclic impact-sliding test using a set of proper loading. The results show that to choose a proper combination of coating, interface and substrate based on their mechanical properties is of great importance under the test condition. Hard substrates provide support

The Dynamic Evolution of Firms’ Pollution Control Strategy under Graded Reward-Penalty Mechanism

OpenAIRE

Li Ming Chen; Wen Ping Wang

2016-01-01

The externality of pollution problem makes firms lack enough incentive to reduce pollution emission. Therefore, it is necessary to design a reasonable environmental regulation mechanism so as to effectively urge firms to control pollution. In order to inspire firms to control pollution, we divide firms into different grades according to their pollution level and construct an evolutionary game model to analyze the interaction between government’s regulation and firms’ pollution control under g...

Novel instrument for characterizing comprehensive physical properties under multi-mechanical loads and multi-physical field coupling conditions

Science.gov (United States)

Liu, Changyi; Zhao, Hongwei; Ma, Zhichao; Qiao, Yuansen; Hong, Kun; Ren, Zhuang; Zhang, Jianhai; Pei, Yongmao; Ren, Luquan

2018-02-01

Functional materials represented by ferromagnetics and ferroelectrics are widely used in advanced sensor and precision actuation due to their special characterization under coupling interactions of complex loads and external physical fields. However, the conventional devices for material characterization can only provide a limited type of loads and physical fields and cannot simulate the actual service conditions of materials. A multi-field coupling instrument for characterization has been designed and implemented to overcome this barrier and measure the comprehensive physical properties under complex service conditions. The testing forms include tension, compression, bending, torsion, and fatigue in mechanical loads, as well as different external physical fields, including electric, magnetic, and thermal fields. In order to offer a variety of information to reveal mechanical damage or deformation forms, a series of measurement methods at the microscale are integrated with the instrument including an indentation unit and in situ microimaging module. Finally, several coupling experiments which cover all the loading and measurement functions of the instrument have been implemented. The results illustrate the functions and characteristics of the instrument and then reveal the variety in mechanical and electromagnetic properties of the piezoelectric transducer ceramic, TbDyFe alloy, and carbon fiber reinforced polymer under coupling conditions.

Research on the mechanical characteristic of the bentonite mixture material under the groundwater environment of Horonobe. 2

International Nuclear Information System (INIS)

Takaji, Kazuhiko; Shigeno, Yoshimasa; Simogouchi, Takafumi

2005-02-01

In the Horonobe underground research project, various in-situ experiments are conducted in order to confirm the applicability of the Engineered Barrier System (EBS) design techniques shown in H12 report, to understand the long-term effects of EBS, and to improve the reliability of the prediction method. Moreover, since it is assumed that the circumference of Horonobe underground research laboratory is the saline water environment, to understand the mechanical behavior of the bentonite mixture material under the saline water environment is important when influenced in design of in-situ experiments. In this study, unconfined compression tests, consolidated-undrained triaxial compression tests and long-term consolidation tests of the bentonite mixture material were performed using groundwater that is extracted near the Horonobe underground research laboratory, and simulation analyses of EBS over a period of time using the results of laboratory experiments etc. were carried out. Consequently, although compressive strength and the elastic modulus under the saline water environment declined compared with that the fresh water, neither shear deformation behavior under triaxial stress condition nor volume deformation behavior by consolidation test almost had a difference, and it was suggested that there were few possibilities that the saline water had serious influence mechanically also about long-term mechanical behavior. (author)

Towards identifying the mechanisms underlying field-aligned edge-loss of HHFW power on NSTX

International Nuclear Information System (INIS)

Perkins, R. J.; Bell, R. E.; Bertelli, N.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; LeBlanc, B. P.; Kramer, G. J.; Maingi, R.; Phillips, C. K.; Podestà, M.; Roquemore, L.; Scotti, F.; Taylor, G.; Wilson, J. R.; Ahn, J-W.; Gray, T. K.; Green, D. L.; McLean, A.

2014-01-01

Fast-wave heating will be a major heating scheme on ITER, as it can heat ions directly and is relatively unaffected by the large machine size unlike neutral beams. However, fast-wave interactions with the plasma edge can lead to deleterious effects such as, in the case of the high-harmonic fast-wave (HHFW) system on NSTX, large losses of fast-wave power in the scrape off layer (SOL) under certain conditions. In such scenarios, a large fraction of the lost HHFW power is deposited on the upper and lower divertors in bright spiral shapes. The responsible mechanism(s) has not yet been identified but may include fast-wave propagation in the scrape off layer, parametric decay instability, and RF currents driven by the antenna reactive fields. Understanding and mitigating these losses is important not only for improving the heating and current-drive on NSTX-Upgrade but also for understanding fast-wave propagation across the SOL in any fast-wave system. This talk summarizes experimental results demonstrating that the flow of lost HHFW power to the divertor regions largely follows the open SOL magnetic field lines. This lost power flux is relatively large close to both the antenna and the last closed flux surface with a reduced level in between, so the loss mechanism cannot be localized to the antenna. At the same time, significant losses also occur along field lines connected to the inboard edge of the bottom antenna plate. The power lost within the spirals is roughly estimated, showing that these field-aligned losses to the divertor are significant but may not account for the total HHFW loss. To elucidate the role of the onset layer for perpendicular fast-wave propagation with regards to fast-wave propagation in the SOL, a cylindrical cold-plasma model is being developed. This model, in addition to advanced RF codes such as TORIC and AORSA, is aimed at identifying the underlying mechanism(s) behind these SOL losses, to minimize their effects in NSTX-U, and to predict

Towards identifying the mechanisms underlying field-aligned edge-loss of HHFW power on NSTX

Energy Technology Data Exchange (ETDEWEB)

Perkins, R. J.; Bell, R. E.; Bertelli, N.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; LeBlanc, B. P.; Kramer, G. J.; Maingi, R.; Phillips, C. K.; Podestà, M.; Roquemore, L.; Scotti, F.; Taylor, G.; Wilson, J. R. [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Ahn, J-W.; Gray, T. K.; Green, D. L.; McLean, A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); and others

2014-02-12

Fast-wave heating will be a major heating scheme on ITER, as it can heat ions directly and is relatively unaffected by the large machine size unlike neutral beams. However, fast-wave interactions with the plasma edge can lead to deleterious effects such as, in the case of the high-harmonic fast-wave (HHFW) system on NSTX, large losses of fast-wave power in the scrape off layer (SOL) under certain conditions. In such scenarios, a large fraction of the lost HHFW power is deposited on the upper and lower divertors in bright spiral shapes. The responsible mechanism(s) has not yet been identified but may include fast-wave propagation in the scrape off layer, parametric decay instability, and RF currents driven by the antenna reactive fields. Understanding and mitigating these losses is important not only for improving the heating and current-drive on NSTX-Upgrade but also for understanding fast-wave propagation across the SOL in any fast-wave system. This talk summarizes experimental results demonstrating that the flow of lost HHFW power to the divertor regions largely follows the open SOL magnetic field lines. This lost power flux is relatively large close to both the antenna and the last closed flux surface with a reduced level in between, so the loss mechanism cannot be localized to the antenna. At the same time, significant losses also occur along field lines connected to the inboard edge of the bottom antenna plate. The power lost within the spirals is roughly estimated, showing that these field-aligned losses to the divertor are significant but may not account for the total HHFW loss. To elucidate the role of the onset layer for perpendicular fast-wave propagation with regards to fast-wave propagation in the SOL, a cylindrical cold-plasma model is being developed. This model, in addition to advanced RF codes such as TORIC and AORSA, is aimed at identifying the underlying mechanism(s) behind these SOL losses, to minimize their effects in NSTX-U, and to predict

Concurrent material-fabrication optimization of metal-matrix laminates under thermo-mechanical loading

Science.gov (United States)

Saravanos, D. A.; Morel, M. R.; Chamis, C. C.

1991-01-01

A methodology is developed to tailor fabrication and material parameters of metal-matrix laminates for maximum loading capacity under thermomechanical loads. The stresses during the thermomechanical response are minimized subject to failure constrains and bounds on the laminate properties. The thermomechanical response of the laminate is simulated using nonlinear composite mechanics. Evaluations of the method on a graphite/copper symmetric cross-ply laminate were performed. The cross-ply laminate required different optimum fabrication procedures than a unidirectional composite. Also, the consideration of the thermomechanical cycle had a significant effect on the predicted optimal process.

Kidney branching morphogenesis under the control of a ligand–receptor-based Turing mechanism

International Nuclear Information System (INIS)

Menshykau, Denis; Iber, Dagmar

2013-01-01

The main signalling proteins that control early kidney branching have been defined. Yet the underlying mechanism is still elusive. We have previously shown that a Schnakenberg-type Turing mechanism can recapitulate the branching and protein expression patterns in wild-type and mutant lungs, but it is unclear whether this mechanism would extend to other branched organs that are regulated by other proteins. Here, we show that the glial cell line-derived neurotrophic factor–RET regulatory interaction gives rise to a Schnakenberg-type Turing model that reproduces the observed budding of the ureteric bud from the Wolffian duct, its invasion into the mesenchyme and the observed branching pattern. The model also recapitulates all relevant protein expression patterns in wild-type and mutant mice. The lung and kidney models are both based on a particular receptor–ligand interaction and require (1) cooperative binding of ligand and receptor, (2) a lower diffusion coefficient for the receptor than for the ligand and (3) an increase in the receptor concentration in response to receptor–ligand binding (by enhanced transcription, more recycling or similar). These conditions are met also by other receptor–ligand systems. We propose that ligand–receptor-based Turing patterns represent a general mechanism to control branching morphogenesis and other developmental processes. (paper)

Ageing under mechanical stress: first experiments for a silver based multilayer mirror

Science.gov (United States)

Lalo, Arnaud; Ravel, Guillaume; Ignat, Michel; Cousin, Bernard; Swain, Michael V.

2017-11-01

Improving materials and devices reliability is a major concern to the spatial industry. Results are reported for satellite mirrors-like specimens consisting in oxide-protected metal systems. Optical coatings were deposited by electron beam evaporation. Mechanical stress fields in multi-layered materials play an important role. The stress state can have far-reaching implications both in kinetics and thermodynamics. Therefore an integrated apparatus with four-point bending equipment was designed. The technique allowed us to exert stress into a film or a system of films on a substrate concurrently with thermal treatment. In order to achieve the first tests performed with the help of the apparatus, various preliminary characterizations were required. The article reports the preliminary micro-mechanical testing of the materials (ultra micro-indentation to evaluate the elastic modulus of the samples materials and wafer curvature technique to determine the specimen residual stress) and the first ageing experiment. Experimental evidence of accelerated ageing under stress is successfully reported.

Microscale experimental investigation of deformation and damage of argillaceous rocks under cyclic hydric and mechanical loads

International Nuclear Information System (INIS)

Wang, Linlin; Yang, Diansen; Heripre, Eva; Chanchole, Serge; Bornert, Michel; Pouya, Ahmad; Halphen, Bernard

2012-01-01

Document available in abstract form only. Argillaceous rocks are possible host rocks for underground nuclear waste repositories. They exhibit complex coupled thermo-hydro-chemo-mechanical behavior, the description of which would strongly benefit from an improved experimental insight on their deformation and damage mechanisms at microscale. We present some recent observations of the evolution of these rocks at the scale of their composite microstructure, essentially made of a clay matrix with embedded carbonates and quartz particles with sizes ranging from a few to several tens of micrometers, when they are subjected to cyclic variations of relative humidity and mechanical loading. They are based on the combination of high definition and high resolution imaging in an environmental scanning electron microscope (ESEM), in situ hydro-mechanical loading of the samples, and digital image correlation techniques. Samples, several millimeters in diameter, are held at a constant temperature of 2 deg. Celsius while the vapor pressure in the ESEM chamber is varied from a few to several hundreds of Pascals, generating a relative humidity ranging from about 10% up to 90%. Results show a strongly heterogeneous deformation field at microscale, which is the result of complex hydro-mechanical interactions. In particular, it can be shown that local swelling incompatibilities can generate irreversible deformations in the clay matrix, even if the overall hydric deformations seem reversible. In addition, local damage can be generated, in the form of a network of microcracks, located in the bulk of the clay matrix and/or at the interface between clay and other mineral particles. The morphology of this network, described in terms of crack length, orientation and preferred location, has been observed to be dependent on the speed of the variation of the relative humidity, and is different in a saturation or desaturation process. Besides studying the deformation and damage under hydric

Enhancement of radiation effect using beta-lapachone and underlying mechanism

International Nuclear Information System (INIS)

Ahn, Ki Jung; Lee, Hyung Sik; Bai, Se Kyung; Song, Chang Won

2013-01-01

Beta-lapachone (β-Lap; 3,4-dihydro-2, 2-dimethyl-2H-naphthol[1, 2-b]pyran-5,6-dione) is a novel anti-cancer drug under phase I/II clinical trials. (β-Lap has been demonstrated to cause apoptotic and necrotic death in a variety of human cancer cells in vitro and in vivo. The mechanisms underlying the (β-Lap toxicity against cancer cells has been controversial. The most recent view is that (β-Lap, which is a quinone compound, undergoes two-electron reduction to hydroquinone form utilizing NAD(P)H or NADH as electron source. This two-electron reduction of (β-Lap is mediated by NAD(P)H:quinone oxidoreductase (NQO1), which is known to mediate the reduction of many quinone compounds. The hydroquinone forms of (β-Lap then spontaneously oxidizes back to the original oxidized (β-Lap, creating futile cycling between the oxidized and reduced forms of (β-Lap. It is proposed that the futile recycling between oxidized and reduced forms of (β-Lap leads to two distinct cell death pathways. First one is that the two-electron reduced (β-Lap is converted first to one-electron reduced (β-Lap, i.e., semiquinone (β-Lap (SQ)- causing production of reactive oxygen species (ROS), which then causes apoptotic cell death. The second mechanism is that severe depletion of NAD(P)H and NADH as a result of futile cycling between the quinone and hydroquinone forms of β- p causes severe disturbance in cellular metabolism leading to apoptosis and necrosis. The relative importance of the aforementioned two mechanisms, i.e., generation of ROS or depletion of NAD(P)H/NADH, may vary depending on cell type and environment. Importantly, the NQO1 level in cancer cells has been found to be higher than that in normal cells indicating that β-Lap may be preferentially toxic to cancer cells relative to non-cancer cells. The cellular level of NQO1 has been found to be significantly increased by divergent physical and chemical stresses including ionizing radiation. Recent reports clearly demonstrated

Neural Mechanisms Underlying Risk and Ambiguity Attitudes.

Science.gov (United States)

Blankenstein, Neeltje E; Peper, Jiska S; Crone, Eveline A; van Duijvenvoorde, Anna C K

2017-11-01

Individual differences in attitudes to risk (a taste for risk, known probabilities) and ambiguity (a tolerance for uncertainty, unknown probabilities) differentially influence risky decision-making. However, it is not well understood whether risk and ambiguity are coded differently within individuals. Here, we tested whether individual differences in risk and ambiguity attitudes were reflected in distinct neural correlates during choice and outcome processing of risky and ambiguous gambles. To these ends, we developed a neuroimaging task in which participants ( n = 50) chose between a sure gain and a gamble, which was either risky or ambiguous, and presented decision outcomes (gains, no gains). From a separate task in which the amount, probability, and ambiguity level were varied, we estimated individuals' risk and ambiguity attitudes. Although there was pronounced neural overlap between risky and ambiguous gambling in a network typically related to decision-making under uncertainty, relatively more risk-seeking attitudes were associated with increased activation in valuation regions of the brain (medial and lateral OFC), whereas relatively more ambiguity-seeking attitudes were related to temporal cortex activation. In addition, although striatum activation was observed during reward processing irrespective of a prior risky or ambiguous gamble, reward processing after an ambiguous gamble resulted in enhanced dorsomedial PFC activation, possibly functioning as a general signal of uncertainty coding. These findings suggest that different neural mechanisms reflect individual differences in risk and ambiguity attitudes and that risk and ambiguity may impact overt risk-taking behavior in different ways.

Mechanisms underlying reduced fertility in anovular dairy cows.

Science.gov (United States)

Santos, J E P; Bisinotto, R S; Ribeiro, E S

2016-07-01

Resumption of ovulation after parturition is a coordinated process that involves recoupling of the GH/insulin-like growth factor 1 axis in the liver, increase in follicular development and steroidogenesis, and removal of negative feedback from estradiol in the hypothalamus. Infectious diseases and metabolic disorders associated with extensive negative energy balance during early lactation disrupt this pathway and delay first ovulation postpartum. Extended periods of anovulation postpartum exert long-lasting effects on fertility in dairy cows including the lack of spontaneous estrus, reduced pregnancy per artificial insemination (P/AI), and increased risk of pregnancy loss. Concentrations of progesterone in anovular cows subjected to synchronized programs for AI are insufficient to optimize follicular maturation, oocyte competence, and subsequent fertility to AI. Ovulation of first wave follicles, which develop under low concentrations of progesterone, reduces embryo quality in the first week after fertilization and P/AI in dairy cows. Although the specific mechanisms by which anovulation and low concentrations of progesterone impair oocyte quality have not been defined, studies with persistent follicles support the involvement of premature resumption of meiosis and degradation of maternal RNA. Suboptimal concentrations of progesterone before ovulation also increase the synthesis of PGF2α in response to oxytocin during the subsequent estrous cycle, which explains the greater incidence of short luteal phases after the first AI postpartum in anovular cows compared with estrous cyclic herd mates. It is suggested that increased spontaneous luteolysis early in the estrous cycle is one of the mechanisms that contributes to early embryonic losses in anovular cows. Anovulation also leads to major shifts in gene expression in elongated conceptuses during preimplantation stages of pregnancy. Transcripts involved with control of energy metabolism and DNA repair were

Tooth wear and wear investigations in dentistry.

Science.gov (United States)

Lee, A; He, L H; Lyons, K; Swain, M V

2012-03-01

Tooth wear has been recognised as a major problem in dentistry. Epidemiological studies have reported an increasing prevalence of tooth wear and general dental practitioners see a greater number of patients seeking treatment with worn dentition. Although the dental literature contains numerous publications related to management and rehabilitation of tooth wear of varying aetiologies, our understanding of the aetiology and pathogenesis of tooth wear is still limited. The wear behaviour of dental biomaterials has also been extensively researched to improve our understanding of the underlying mechanisms and for the development of restorative materials with good wear resistance. The complex nature of tooth wear indicates challenges for conducting in vitro and in vivo wear investigations and a clear correlation between in vitro and in vivo data has not been established. The objective was to critically review the peer reviewed English-language literature pertaining to prevalence and aetiology of tooth wear and wear investigations in dentistry identified through a Medline search engine combined with hand-searching of the relevant literature, covering the period between 1960 and 2011. © 2011 Blackwell Publishing Ltd.

Colloid and radionuclide retention mechanisms in fractured rock under near-natural flow conditions

International Nuclear Information System (INIS)

Delos, A.; Schaefer, T.; Geckeis, H.; Guimera, J.; Carrera, J.; Fanghaenel, T.

2005-01-01

Full text of publication follows: Experiments in fractured host rock (Grimsel Test Site, GTS, Switzerland) revealed that the colloid relevance for actinide migration is high due to the specific geochemical groundwater conditions [1]. However, even under such conditions it is found that retention of colloids and colloid-borne actinides becomes significant under near-natural groundwater flow rates (1-10 m/a) [2]. Underlying mechanisms of colloid and radionuclide retention are not well understood up to now. The present study co-funded by the NoE ACTINET-6 focuses on (i) the kinetics of actinide-colloid interactions and (ii) the relevance of matrix diffusion as a competition process to other retention mechanisms which affect the actinides behavior in fractured rock systems such as the Grimsel granodiorite. Colloid migration is studied with well defined model colloids as e.g. fluorescence dyed carboxylated polystyrene particles, and natural colloids extracted from bentonite (FEBEX) and from fracture filling material (GTS). In order to study the influence of matrix porosity on actinides migration, those experiments are performed in columns of well defined geometry filled with microporous unmodified silica spheres, porous ceramic material and natural fracture filling material from the GTS. The behaviour of actinides (Pu(IV) and Am(III)) sorbed onto bentonite colloids is investigated in column and batch experiments. All experiments are performed under anoxic conditions. Colloid characterization methods used in this study include the combination of photon correlation spectroscopy (PCS), laser-induced breakdown detection (LIBD), fluorimetry and field flow fractionation (FFF). Experimental results and their application to the parametrisation of reactive colloid transport models are discussed. [1] Geckeis H, Schaefer T, Hauser W, Rabung T, Missana T, Degueldre C, Moeri A, Eikenberg J, Fierz T, Alexander WR (2004) Results of the Colloid and Radionuclide Retention experiment

Reversible pulmonary hypertension in Whipple disease: a case report with clinicopathological implications, and literature review

OpenAIRE

Lyle, Pamela L; Weber, Robert D; Bogarin, Javier; Kircher, Tobias

2009-01-01

Whipple disease is a rare multisystemic disorder of infectious aetiology caused by Tropheryma whipplei. Pulmonary hypertension is a rare association for which the underlying pathophysiological mechanism is unclear. Our patient was a 54-year-old man with a 1-year history of progressive polyarticular arthritis, and worsening respiratory and gastrointestinal symptoms. Pulmonary artery catheterisation demonstrated moderate-to-severe pulmonary hypertension. Duodenal biopsies, with electron microsc...

Mechanical response of collagen molecule under hydrostatic compression

International Nuclear Information System (INIS)

Saini, Karanvir; Kumar, Navin

2015-01-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

Mechanical response of collagen molecule under hydrostatic compression.

Science.gov (United States)

Saini, Karanvir; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials. Copyright © 2015 Elsevier B.V. All rights

Mechanical response of collagen molecule under hydrostatic compression

Energy Technology Data Exchange (ETDEWEB)

Saini, Karanvir, E-mail: karans@iitrpr.ac.in; Kumar, Navin

2015-04-01

Proteins like collagen are the basic building blocks of various body tissues (soft and hard). Collagen molecules find their presence in the skeletal system of the body where they bear mechanical loads from different directions, either individually or along with hydroxy-apatite crystals. Therefore, it is very important to understand the mechanical behavior of the collagen molecule which is subjected to multi-axial state of loading. The estimation of strains of collagen molecule along different directions resulting from the changes in hydrostatic pressure magnitude, can provide us new insights into its mechanical behavior. In the present work, full atomistic simulations have been used to study global (volumetric) as well as local (along different directions) mechanical properties of the hydrated collagen molecule which is subjected to different hydrostatic pressure magnitudes. To estimate the local mechanical properties, the strains of collagen molecule along its longitudinal and transverse directions have been acquired at different hydrostatic pressure magnitudes. In spite of non-homogeneous distribution of atoms within the collagen molecule, the calculated values of local mechanical properties have been found to carry the same order of magnitude along the longitudinal and transverse directions. It has been demonstrated that the values of global mechanical properties like compressibility, bulk modulus, etc. as well as local mechanical properties like linear compressibility, linear elastic modulus, etc. are functions of magnitudes of applied hydrostatic pressures. The mechanical characteristics of collagen molecule based on the atomistic model have also been compared with that of the continuum model in the present work. The comparison showed up orthotropic material behavior for the collagen molecule. The information on collagen molecule provided in the present study can be very helpful in designing the future bio-materials.

Mechanical behavior of confined self-compacting reinforced concrete circular columns under concentric axial loading

Directory of Open Access Journals (Sweden)

Fouad Khairallah

2013-12-01

Full Text Available While there is abundant research information on ordinary confined concrete, there are little data on the behavior of Self-Compacting Concrete (SCC under such condition. Due to higher shrinkage and lower coarse aggregate content of SCC compared to that of Normal Concrete (NC, its composite performance under confined conditions needs more investigation. This paper has been devoted to investigate and compare the mechanical behavior of confined concrete circular columns cast with SCC and NC under concentric axial loading. The parameters affecting are including concrete compressive strength and confinement configuration. Twenty column specimens were casted and confined using four confinement techniques, CFRP wrap, FRP tube, GFRP wrap, and spiral steel hoops. The performance of the tested column specimens is evaluated based on mode of failure, load–displacement curve, stress–strain characteristics, ultimate strength, ductility, and degree of confinement.

Structural integrity and failure mechanisms of a smart piezoelectric actuator under a cyclic bending mode

International Nuclear Information System (INIS)

Woo, Sung-Choong; Goo, Nam Seo

2008-01-01

Information on the onset and evolution of damage within materials is essential for guaranteeing the integrity of actuator systems. The authors have evaluated the structural integrity and the failure mechanisms of smart composite actuators with a PZT ceramic plate under electric cyclic loading. For this, two kinds of actuators, actuator 1 and actuator 2, were manufactured. Prior to the main testing, performance testing was performed on the actuators to determine their resonant frequencies. Electric cyclic tests were conducted up to twenty million cycles. An acoustic emission technique was used for monitoring the damage evolution in real time. We observed the extent of the damage after testing using scanning electron microscopy and reflected optical microscopy to support characteristics in the acoustic emission behavior that corresponded to specific types of damage mechanisms. It was shown that the initial damage mechanism of the smart composite actuator under electric cyclic loading originated from the transgranular micro-fatigue damage in the PZT ceramic layer. With increasing cycles, a local intergranular crack initiated and developed onto the surface of the PZT ceramic layer or propagated into the internal layer. Finally, short-circuiting led to the electric breakdown of the actuator. These results were different depending on the drive frequencies and the configuration of the actuators. Moreover, we differentiated between the aforementioned damage mechanisms via AE signal pattern analyses based on the primary frequency and the waveform. From our results, we conclude that the drive frequency and the existence of a protecting layer are dominant factors in the structural integrity of the smart composite actuator

Mechanical properties of novel forms of graphyne under strain: A density functional theory study

Science.gov (United States)

Majidi, Roya

2017-06-01

The mechanical properties of two forms of graphyne sheets named α-graphyne and α2-graphyne under uniaxial and biaxial strains were studied. In-plane stiffness, bulk modulus, and shear modulus were calculated based on density functional theory. The in-plane stiffness, bulk modulus, and shear modulus of α2-graphyne were found to be larger than that of α-graphyne. The maximum values of supported uniaxial and biaxial strains before failure were determined. The α-graphyne was entered into the plastic region with the higher magnitude of tension in comparison to α2-graphyne. The mechanical properties of α-graphyne family revealed that these forms of graphyne are proper materials for use in nanomechanical applications.

Modulating Conscious Movement Intention by Noninvasive Brain Stimulation and the Underlying Neural Mechanisms

OpenAIRE

Douglas, Zachary H.; Maniscalco, Brian; Hallett, Mark; Wassermann, Eric M.; He, Biyu J.

2015-01-01

Conscious intention is a fundamental aspect of the human experience. Despite long-standing interest in the basis and implications of intention, its underlying neurobiological mechanisms remain poorly understood. Using high-definition transcranial DC stimulation (tDCS), we observed that enhancing spontaneous neuronal excitability in both the angular gyrus and the primary motor cortex caused the reported time of conscious movement intention to be ∼60–70 ms earlier. Slow brain waves recorded ∼2–...

Linear Analytical Solutions of Mechanical Sensitivity in Large Deflection of Unsymmetrically Layered Piezoelectric Plate under Pretension

Directory of Open Access Journals (Sweden)

Chun-Fu Chen

2014-03-01

Full Text Available Linear analytical study on the mechanical sensitivity in large deflection of unsymmetrically layered and laterally loaded piezoelectric plate under pretension is conducted. von Karman plate theory for large deflection is utilized but extended to the case of an unsymmetrically layered plate embedded with a piezoelectric layer. The governing equations thus obtained are simplified by omitting the arising nonlinear terms, yielding a Bessel or modified Bessel equation for the lateral slope. Depending on the relative magnitude of the piezoelectric effect, for both cases, analytical solutions of various geometrical responses are developed and formulated via Bessel and modified Bessel functions. The associated ultimate radial stresses are further derived following lamina constitutive law to evaluate the mechanical sensitivity of the considered plate. For a nearly monolithic plate under a very low applied voltage, the results are in good agreement with those for a single-layered case due to pure mechanical load available in literature, and thus the present approach is checked. For a two-layered unsymmetric plate made of typical silicon-based materials, a sound piezoelectric effect is illustrated particularly in a low pretension condition.

Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

Directory of Open Access Journals (Sweden)

Shi-Jian Zhu

2014-01-01

Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

Coral bleaching under thermal stress: putative involvement of host/symbiont recognition mechanisms

Directory of Open Access Journals (Sweden)

Tambutte Sylvie

2009-08-01

Full Text Available Abstract Background Coral bleaching can be defined as the loss of symbiotic zooxanthellae and/or their photosynthetic pigments from their cnidarian host. This major disturbance of reef ecosystems is principally induced by increases in water temperature. Since the beginning of the 1980s and the onset of global climate change, this phenomenon has been occurring at increasing rates and scales, and with increasing severity. Several studies have been undertaken in the last few years to better understand the cellular and molecular mechanisms of coral bleaching but the jigsaw puzzle is far from being complete, especially concerning the early events leading to symbiosis breakdown. The aim of the present study was to find molecular actors involved early in the mechanism leading to symbiosis collapse. Results In our experimental procedure, one set of Pocillopora damicornis nubbins was subjected to a gradual increase of water temperature from 28°C to 32°C over 15 days. A second control set kept at constant temperature (28°C. The differentially expressed mRNA between the stressed states (sampled just before the onset of bleaching and the non stressed states (control were isolated by Suppression Subtractive Hybridization. Transcription rates of the most interesting genes (considering their putative function were quantified by Q-RT-PCR, which revealed a significant decrease in transcription of two candidates six days before bleaching. RACE-PCR experiments showed that one of them (PdC-Lectin contained a C-Type-Lectin domain specific for mannose. Immunolocalisation demonstrated that this host gene mediates molecular interactions between the host and the symbionts suggesting a putative role in zooxanthellae acquisition and/or sequestration. The second gene corresponds to a gene putatively involved in calcification processes (Pdcyst-rich. Its down-regulation could reflect a trade-off mechanism leading to the arrest of the mineralization process under stress

Mechanisms underlying the antihypertensive properties of Urtica dioica.

Science.gov (United States)

Qayyum, Rahila; Qamar, Hafiz Misbah-Ud-Din; Khan, Shamim; Salma, Umme; Khan, Taous; Shah, Abdul Jabbar

2016-09-01

Urtica dioica has traditionally been used in the management of cardiovascular disorders especially hypertension. The aim of this study was to explore pharmacological base of its use in hypertension. Crude methanolic extract of U. dioica (Ud.Cr) and its fractions (Ud.EtAc, Ud.nHex, Ud.Chl and Ud.Aq) were tested in vivo on normotensive and hypertensive rats under anesthesia for blood pressure lowering effect. In-vitro experiments on rat and rabbit aortae were employed to probe the vasorelaxation mechanism(s). The responses were measured using pressure and force transducers connected to PowerLab Data Acquisition System. Ud.Cr and fractions were found more effective antihypertensive in hypertensive rats than normotensive with remarkable potency exhibited by the ethyl acetate fraction. The effect was same in the presence of atropine. In isolated rat aortic rings, Ud.Cr and all its fractions exhibited L-NAME sensitive endothelium-dependent vasodilator effect and also inhibit K(+) (80 mM)-induced pre-contractions. In isolated rabbit thoracic aortic rings Ud.Cr and its fractions induced relaxation with more potency against K(+) (80 mM) than phenylephrine (1 µM) like verapamil, showing Ud.EtAc fraction the most potent one. Pre-incubation of aortic rings with Ud.Cr and its fractions exhibited Ca(2+) channel blocking activity comparable with verapamil by shifting Ca(2+) concentration response curves to the right. Ud.Cr and its fractions also ablated the intracellular Ca(2+) release by suppressing PE peak formation in Ca(2+) free medium. When tested on basal tension, the crude extract and all fractions were devoid of any vasoconstrictor effect. These data indicate that crude methanolic extract and its fractions possess antihypertensive effect. Identification of NO-mediated vasorelaxation and calcium channel blocking effects explain the antihypertensive potential of U. dioica and provide a potential pharmacological base to its medicinal use in the management of hypertension.

Numerical and experimental characterization of ceramic pebble beds under cycling mechanical loading

Energy Technology Data Exchange (ETDEWEB)

Pupeschi, S., E-mail: pupeschi.simone@hotmail.it [Institute for Applied Materials, Karlsruhe Institute of Technology (KIT) (Germany); Knitter, R.; Kamlah, M. [Institute for Applied Materials, Karlsruhe Institute of Technology (KIT) (Germany); Gan, Y. [School of Civil Engineering, The University of Sydney, Sydney, NSW, 2006 (Australia)

2016-11-15

Highlights: • The effect of cyclic loading on the mechanical response of pebble beds was assessed. • Numerical simulations were performed with KIT-DEM code. • The numerical simulations were compared with the experimental outcomes. • A good qualitative agreement between experimental and simulation results was found. • The pebble size distribution affects the mechanical response of the assemblies. - Abstract: All solid breeder concepts considered to be tested in ITER (International Thermonuclear Experimental Reactor), make use of lithium-based ceramics in the form of pebble-packed beds as tritium breeder. A thorough understanding of the thermal and mechanical properties of the ceramic pebble beds under fusion relevant conditions is essential for the design of the breeder blanket modules of future fusion reactors. In this study, the effect of cyclic loading on the mechanical behaviour of pebble bed assemblies was investigated using a Discrete Element Method (DEM) code. The numerical simulations were compared with the experimental outcomes. The results of numerical simulations show that the pebble size distribution affects noticeably the stress-strain behaviour of the assemblies. A good qualitative agreement between experimental and simulation results was found in terms of difference between residual strains of consecutive cycles. An increase of the oedometric modulus with the compressive load was observed for all investigated compositions in both experimental and DEM simulations. The numerical results show an increase of the oedometric modulus (E) with progressive compaction of the assemblies due to the cycling loading, while no significant influence of the pebbles size distribution was observed.

Mechanisms shaping the development of personality and personality disorders in children and adolescents.

Science.gov (United States)

Lenkiewicz, Kamila; Srebnicki, Tomasz; Bryńska, Anita

2016-01-01

Until the end of the nineties last century personality disorders could not be diagnosed before the age of eighteen. Nevertheless, the results of studies published in the last decade have revealed that personality disorders can be observed in children and adolescents and that personality disorders diagnosed in adult patients had been present as early as in childhood. The knowledge of possible mechanisms shaping personality disorders in childhood is unsatisfactory and needs to be expanded. Developmental psychology explains the development of abnormal personality through inappropriate attachment patterns and abnormal transitions between developmental phases. Genetic and temperamental factors are also important in the aetiology of personality disorders as well as early maladaptive schemas resulting from personal experiences and interactions with others. The aim of this article is to review the current knowledge on the mechanisms shaping the development of personality and personality disorders in childhood and adolescence.

A multi-scale approach of mechanical and transport properties of cementitious materials under rises of temperature

International Nuclear Information System (INIS)

Caratini, G.

2012-01-01

The modern industrial activities (storage of nuclear waste, geothermal wells, nuclear power plants,...) can submit cementitious materials to some extreme conditions, for example at temperatures above 200 C. This level of temperature will induce phenomena of dehydration in the cement paste, particularly impacting the CSH hydrates which led to the mechanical cohesion. The effects of these temperatures on the mechanical and transport properties have been the subject of this thesis.To understand these effects, we need to take into account the heterogeneous, porous, multi-scale aspects of these materials. To do this, micro-mechanics and homogenization tools based on the Eshelby problem's solution were used. Moreover, to support this multi-scale modeling, mechanical testing based on the theory of porous media were conducted. The measurements of modulus compressibility, permeability and porosity under confining pressure were used to investigate the mechanisms of degradation of these materials during thermal loads up to 400 C. (author)

Mechanical and electronic properties of monolayer and bilayer phosphorene under uniaxial and isotropic strains.

Science.gov (United States)

Hu, Ting; Han, Yang; Dong, Jinming

2014-11-14

The mechanical and electronic properties of both the monolayer and bilayer phosphorenes under either isotropic or uniaxial strain have been systematically investigated using first-principles calculations. It is interesting to find that: 1) Under a large enough isotropic tensile strain, the monolayer phosphorene would lose its pucker structure and transform into a flat hexagonal plane, while two inner sublayers of the bilayer phosphorene could be bonded due to its interlayer distance contraction. 2) Under the uniaxial tensile strain along a zigzag direction, the pucker distance of each layer in the bilayer phosphorene can exhibit a specific negative Poisson's ratio. 3) The electronic properties of both the monolayer and bilayer phosphorenes are sensitive to the magnitude and direction of the applied strains. Their band gaps decrease more rapidly under isotropic compressive strain than under uniaxial strain. Also, their direct-indirect band gap transitions happen at the larger isotropic tensile strains compared with that under uniaxial strain. 4) Under the isotropic compressive strain, the bilayer phosphorene exhibits a transition from a direct-gap semiconductor to a metal. In contrast, the monolayer phosphorene initially has the direct-indirect transition and then transitions to a metal. However, under isotropic tensile strain, both the bilayer and monolayer phosphorene show the direct-indirect transition and, finally, the transition to a metal. Our numerical results may open new potential applications of phosphorene in nanoelectronics and nanomechanical devices by external isotropic strain or uniaxial strain along different directions.

PHYSIOLOGICAL QUALITY OF SOYBEAN SEEDS UNDER MECHANICAL INJURIES CAUSED BY COMBINES

Directory of Open Access Journals (Sweden)

FÁBIO PALCZEWSKI PACHECO

2015-01-01

Full Text Available The mechanical harvesting causes injuries on seeds and may affect their quality. Different threshing mechanisms and their adjustments may also affect the intensity of impacts that machines cause on seeds. So, this study aimed at diagnosing and evaluating the effect of two combines: the first one with a threshing system of axial flow and the other one with a threshing system of tangential flow, under adjustments of concave opening (10 mm, 30 mm and 10 mm for a combine with axial flow and 3.0 mm, 15 mm and 3.0 mm for a combine with tangential flow and three cylinder rotations on the quality of soybean seeds harvested at two moisture contents. Soybean seeds of cultivar 'ND 4910' were harvested at 16.6% moisture (mid - morning and 13.7% moisture in the afternoon. The seeds quality was evaluated by germination tests, germination speed index (GSI, germination rate, moisture content, percentage of purity and vigor by tetrazolium test. Despite the combine, the results showed that the mechanical injury has most reduced seeds quality, at 16.6% moisture content, concave opening of 30 mm (axial and 10 mm (tangential and cylinder rotation of 1100 rpm (axial and 1000 (tangential, both with the highest rotations used. The combine with tangential flow had the highest degree of seeds purity. When seeds moisture content at harvest was close to 13.7%, there was the highest seed injury, while, at 16.6%, there was the highest number of crushed soybeans, regardless the combine adjustment.

Mechanical strength of an ITER coil insulation system under static and dynamic load after reactor irradiation

International Nuclear Information System (INIS)

Bittner-Rohrhofer, K.; Humer, K.; Weber, H.W.; Hamada, K.; Sugimoto, M.; Okuno, K.

2002-01-01