126 research outputs found
Texture transitions in the liquid crystalline alkyloxybenzoic acid 6OBAC
The 4,n-alkyloxybenzoic acid 6OBAC has a very rich variety of crystalline
structures and two nematic sub-phases, characterised by different textures. It
is a material belonging to a family of liquid crystals formed by hydrogen
bonded molecules, the 4,n-alkyloxybenzoic acids indicates the homologue
number). The homologues with n ranging from 7 to 13 display both smectic C and
N phases. In spite of the absence of a smectic phase, 6OBAC exhibits two
sub-phases with different textures, as it happens in other materials of the
homologue series which possess the smectic phase. This is the first material
that exhibits a texture transition in a nematic phase directly originated from
a crystal phase. Here we present the results of an image processing assisted
optical investigation to characterise the textures and the transitions between
textures. This processing is necessary to discriminate between crystal
modifications and nematic sub-phases.Comment: 12 pages, 10 figure
Strategies to preserve autologous blood in patients operated on heart under extracorporeal circulation
Departamentul Chirurgie CardiacÄ, IMSP Spitalul Clinic Republican, ChiÈinÄu, Republica Moldova, ConferinÈa stiinÈificÄ âNicolae Anestiadi â nume etern al chirurgiei basarabeneâ consacratÄ centenarului de la naÈterea profesorului Nicolae Anestiadi 26 august 2016Introducere. AtĂąt chirurgie cardiaca cĂźt si caracteristicile tehnice ale circulaÈie extracorporalÄ (CEC) necesita
transfuzie de sĂąnge de la donatori, care implicÄ o serie de riscuri pentru pacienÈi.
Scop. explorarea posibilitÄÈilor de reducere a volumului de transfuzii sĂąngelui homolog, la diferite grupe de
vĂąrstÄ de pacienÈi care necesitÄ intervenÈii chirurgicale cardiace.
Materiale Èi metode. Primul lot de studiu a inclus 250 de copii (131 bÄieÈi, 119 fete), cu greutatea mai micÄ
de 10 kg (10 .45 ± 3.15) Èi 1,4 ± 0.7 ani - vĂąrsta medie, cu vicii cardiace congenitale, care au suportat intevenÈii
chirurgicale Ăźn condiĆŁii de CEC. Ăn cadrul lotului II, au fost incluÈi 223 adulÈi (122 barbati, 101 femei) cu vicii
cardiace dobĂąndite, operaÈi Ăźn condiÈii de CEC.
Rezultate. La toti copii a fost utilizat metoda de restituire a volumului de umplere cu sĂąnge propriu a pacienÈilor,
datorit acestei metode a fost recuperate pĂąnÄ 45 % din âprimingâ . Ăn primul lot de studiu nu a fost nevoie de
hemostaza chirurgicalÄ repetatÄ. Pierderea de sĂąnge a reprezentat 6,2 ml / kg / 24h. Transfuzie postoperatorie de
sĂąnge homolog (masa eritrocitara) au necesitat 73 de copii, 48,66% din Ăźntregul grup. Ăn grupul II au necesitat
hemostaza chirurgicalÄ repetatÄ 5 pacienÈi. Letalitatea a fost de 1,8%(4 pacienÈi).
Concluzii. Minimalizarea perderilor, restituirea primingului cu sĂąnge autolog,utilizarea â Cell saver â, ultrafiltrare
Èi autotransfuzia intraoperatorie ar putea diminua necesitatea de transfuzie de sĂąnge homolog la pacienÈii cu
intervenÈii chirurgicale pe cord deschis.Introduction. Both severity of cardiac surgery and technical features of extracorporeal circulation (CEC) circuit
demands blood transfusion from donors, which involves a number of risks for the patient.
Purpose. To explore the possibilities of reducing the volume of homologous blood transfusion in different age
groups of cardiac surgery patients.
Material and methods. The study group I included 250 children (131 boys, 119 girls) weighting less than 10kg
(10 .45 ± 3.15) and 1.4 ± 0.7 years average age with congenital heart disease, operated on heart under CPB.
In group II patients were included 223 adults (122 men, 101women) with acquired heart disease, operated
under CPB conditions.
Results. No hospital lethality occurred in 1st group and no surgical hemostasis was performed. Blood loss
accounted 6.2 ml/kg /24h. Postoperative transfusion of homologous blood (erythrocyte mass) were needed in
73 children, which consists only 48,66% of whole group. Retrograde autologus blood priming was used with
recuperation till 45 â of priming.In 2nd group surgical hemostasis demanded 5 patients. Lethality was 1,8% (4
patients).
Conclusions. Priming minimalisation and autologous blood priming, Cell Saver usage, ultrafiltration, preand
intraoperative auto transfusion could diminish the necessity of homologous blood transfusion in cardiac
surgery patients
Supporting systematic reviews using LDA-based document representations
BACKGROUND: Identifying relevant studies for inclusion in a systematic review (i.e. screening) is a complex, laborious and expensive task. Recently, a number of studies has shown that the use of machine learning and text mining methods to automatically identify relevant studies has the potential to drastically decrease the workload involved in the screening phase. The vast majority of these machine learning methods exploit the same underlying principle, i.e. a study is modelled as a bag-of-words (BOW). METHODS: We explore the use of topic modelling methods to derive a more informative representation of studies. We apply Latent Dirichlet allocation (LDA), an unsupervised topic modelling approach, to automatically identify topics in a collection of studies. We then represent each study as a distribution of LDA topics. Additionally, we enrich topics derived using LDA with multi-word terms identified by using an automatic term recognition (ATR) tool. For evaluation purposes, we carry out automatic identification of relevant studies using support vector machine (SVM)-based classifiers that employ both our novel topic-based representation and the BOW representation. RESULTS: Our results show that the SVM classifier is able to identify a greater number of relevant studies when using the LDA representation than the BOW representation. These observations hold for two systematic reviews of the clinical domain and three reviews of the social science domain. CONCLUSIONS: A topic-based feature representation of documents outperforms the BOW representation when applied to the task of automatic citation screening. The proposed term-enriched topics are more informative and less ambiguous to systematic reviewers. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13643-015-0117-0) contains supplementary material, which is available to authorized users
Impact of renal impairment on atrial fibrillation: ESC-EHRA EORP-AF Long-Term General Registry
Background: Atrial fibrillation (AF) and renal impairment share a bidirectional relationship with important pathophysiological interactions. We evaluated the impact of renal impairment in a contemporary cohort of patients with AF. Methods: We utilised the ESC-EHRA EORP-AF Long-Term General Registry. Outcomes were analysed according to renal function by CKD-EPI equation. The primary endpoint was a composite of thromboembolism, major bleeding, acute coronary syndrome and all-cause death. Secondary endpoints were each of these separately including ischaemic stroke, haemorrhagic event, intracranial haemorrhage, cardiovascular death and hospital admission. Results: A total of 9306 patients were included. The distribution of patients with no, mild, moderate and severe renal impairment at baseline were 16.9%, 49.3%, 30% and 3.8%, respectively. AF patients with impaired renal function were older, more likely to be females, had worse cardiac imaging parameters and multiple comorbidities. Among patients with an indication for anticoagulation, prescription of these agents was reduced in those with severe renal impairment, p <.001. Over 24 months, impaired renal function was associated with significantly greater incidence of the primary composite outcome and all secondary outcomes. Multivariable Cox regression analysis demonstrated an inverse relationship between eGFR and the primary outcome (HR 1.07 [95% CI, 1.01â1.14] per 10 ml/min/1.73 m2 decrease), that was most notable in patients with eGFR <30 ml/min/1.73 m2 (HR 2.21 [95% CI, 1.23â3.99] compared to eGFR â„90 ml/min/1.73 m2). Conclusion: A significant proportion of patients with AF suffer from concomitant renal impairment which impacts their overall management. Furthermore, renal impairment is an independent predictor of major adverse events including thromboembolism, major bleeding, acute coronary syndrome and all-cause death in patients with AF
Clinical complexity and impact of the ABC (Atrial fibrillation Better Care) pathway in patients with atrial fibrillation: a report from the ESC-EHRA EURObservational Research Programme in AF General Long-Term Registry
Background: Clinical complexity is increasingly prevalent among patients with atrial fibrillation (AF). The âAtrial fibrillation Better Careâ (ABC) pathway approach has been proposed to streamline a more holistic and integrated approach to AF care; however, there are limited data on its usefulness among clinically complex patients. We aim to determine the impact of ABC pathway in a contemporary cohort of clinically complex AF patients. Methods: From the ESC-EHRA EORP-AF General Long-Term Registry, we analysed clinically complex AF patients, defined as the presence of frailty, multimorbidity and/or polypharmacy. A K-medoids cluster analysis was performed to identify different groups of clinical complexity. The impact of an ABC-adherent approach on major outcomes was analysed through Cox-regression analyses and delay of event (DoE) analyses. Results: Among 9966 AF patients included, 8289 (83.1%) were clinically complex. Adherence to the ABC pathway in the clinically complex group reduced the risk of all-cause death (adjusted HR [aHR]: 0.72, 95%CI 0.58â0.91), major adverse cardiovascular events (MACEs; aHR: 0.68, 95%CI 0.52â0.87) and composite outcome (aHR: 0.70, 95%CI: 0.58â0.85). Adherence to the ABC pathway was associated with a significant reduction in the risk of death (aHR: 0.74, 95%CI 0.56â0.98) and composite outcome (aHR: 0.76, 95%CI 0.60â0.96) also in the high-complexity cluster; similar trends were observed for MACEs. In DoE analyses, an ABC-adherent approach resulted in significant gains in event-free survival for all the outcomes investigated in clinically complex patients. Based on absolute risk reduction at 1 year of follow-up, the number needed to treat for ABC pathway adherence was 24 for all-cause death, 31 for MACEs and 20 for the composite outcome. Conclusions: An ABC-adherent approach reduces the risk of major outcomes in clinically complex AF patients. Ensuring adherence to the ABC pathway is essential to improve clinical outcomes among clinically complex AF patients
Impact of clinical phenotypes on management and outcomes in European atrial fibrillation patients: a report from the ESC-EHRA EURObservational Research Programme in AF (EORP-AF) General Long-Term Registry
Background: Epidemiological studies in atrial fibrillation (AF) illustrate that clinical complexity increase the risk of major adverse outcomes. We aimed to describe European AF patients\u2019 clinical phenotypes and analyse the differential clinical course. Methods: We performed a hierarchical cluster analysis based on Ward\u2019s Method and Squared Euclidean Distance using 22 clinical binary variables, identifying the optimal number of clusters. We investigated differences in clinical management, use of healthcare resources and outcomes in a cohort of European AF patients from a Europe-wide observational registry. Results: A total of 9363 were available for this analysis. We identified three clusters: Cluster 1 (n = 3634; 38.8%) characterized by older patients and prevalent non-cardiac comorbidities; Cluster 2 (n = 2774; 29.6%) characterized by younger patients with low prevalence of comorbidities; Cluster 3 (n = 2955;31.6%) characterized by patients\u2019 prevalent cardiovascular risk factors/comorbidities. Over a mean follow-up of 22.5 months, Cluster 3 had the highest rate of cardiovascular events, all-cause death, and the composite outcome (combining the previous two) compared to Cluster 1 and Cluster 2 (all P <.001). An adjusted Cox regression showed that compared to Cluster 2, Cluster 3 (hazard ratio (HR) 2.87, 95% confidence interval (CI) 2.27\u20133.62; HR 3.42, 95%CI 2.72\u20134.31; HR 2.79, 95%CI 2.32\u20133.35), and Cluster 1 (HR 1.88, 95%CI 1.48\u20132.38; HR 2.50, 95%CI 1.98\u20133.15; HR 2.09, 95%CI 1.74\u20132.51) reported a higher risk for the three outcomes respectively. Conclusions: In European AF patients, three main clusters were identified, differentiated by differential presence of comorbidities. Both non-cardiac and cardiac comorbidities clusters were found to be associated with an increased risk of major adverse outcomes
Dielectric measurements of liquid crystals confined to molecular sieves
The molecular dynamics of the liquid crystals 8CB and 5CB confined to the mesopores of the molecular sieve Al-MCM-41 with pore diameter less than 2.5 nm was investigated by broadband dielectric spectroscopy. The phase transitions of the liquid crystal cannot be detected for the molecules confined to the pores. Moreover it has been found that even about 20 K below the melting temperature of the bulk material a relaxation process occurs for molecules confined to the mesoporous material which does not exist in the bulk liquid crystal state. The temperature dependence of the relaxation rate of that process obeys a Vogel-Fulcher-Tammann law
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