1,430 research outputs found
Anisotropic conjugated polymer chain conformation tailors the energy migration in nanofibers
Conjugated polymers are complex multi-chromophore systems, with emission
properties strongly dependent on the electronic energy transfer through active
sub-units. Although the packing of the conjugated chains in the solid state is
known to be a key factor to tailor the electronic energy transfer and the
resulting optical properties, most of the current solution-based processing
methods do not allow for effectively controlling the molecular order, thus
making the full unveiling of energy transfer mechanisms very complex. Here we
report on conjugated polymer fibers with tailored internal molecular order,
leading to a significant enhancement of the emission quantum yield. Steady
state and femtosecond time-resolved polarized spectroscopies evidence that
excitation is directed toward those chromophores oriented along the fiber axis,
on a typical timescale of picoseconds. These aligned and more extended
chromophores, resulting from the high stretching rate and electric field
applied during the fiber spinning process, lead to improved emission
properties. Conjugated polymer fibers are relevant to develop optoelectronic
plastic devices with enhanced and anisotropic properties.Comment: 43 pages, 15 figures, 1 table in Journal of the American Chemical
Society, (2016
Serratia marcescens infection or hypoxic- ischaemic encephalopathy in neonates : is magnetic resonance imaging a problem-solving tool?
To the Editor: We read with great interest the retrospective case series by A Madide and J Smith,[1] describing brain ultrasound (US) findings of neonates with Serratia marcescens hospital-acquired infections. S. marcescens is a Gram-negative organism that frequently colonises neonatal intensive care units (NICUs). This bacterium can cause severe brain infections in neonates, with irreversible neurological damage and long-term neurodevelopmental impairment. The authors conclude that in babies with acute onset of the illness, US scans allow doctors to highlight pathological changes in the brain immediately before the microbiological diagnosis of infection, and to follow the evolution of those lesions. We are in complete agreement with their comments regarding the importance of accurate and timely diagnosis: early treatment, to minimise the bacterial load, seems to have a great impact on outcome. Moreover, it is important to underline that transfontanellar US scans remain the first-line modality of imaging because of their safety, low cost and especially because of their wide availability.[2
Development and Initial Validation of a Questionnaire to Measure Health-Related Quality of Life of Adults with Common Variable Immune Deficiency: The CVID_QoL Questionnaire.
BACKGROUND:
Generic health status quality of life (QoL) instruments have been used in patients with common variable immune deficiency (CVID). However, by their nature, these tools may over- or underestimate the impact of diseases on an individual's QoL.
OBJECTIVE:
The objective of this study was to develop and validate a questionnaire to measure specific-health-related QoL for adults with CVID (CVID_QoL).
METHODS:
The 32-item content of the CVID_QoL questionnaire was developed using focus groups and individual patient interviews. Validation studies included 118 adults with CVID who completed Short Form-36, Saint George Respiratory Questionnaire, General Health Questionnaire-12, and EuroQol-5D questionnaire in a single session. Principal component and factor analysis solutions identified 3 scores to be similar in number and content for each solution. Validation of 3 factor scores was performed by construct validity. Reproducibility, reliability, convergent validity, and discriminant validity were evaluated. Matrices consisting of correlations between the 32 items in the CVID_QOL were calculated.
RESULTS:
Factor analysis identified 3 dimensions: emotional functioning (EF), relational functioning (RF), and gastrointestinal and skin symptoms (GSS). The instrument had good internal consistency (Cronbach's alpha, min. 0.74 for GSS, max. 0.84 for RF, n = 118) and high reproducibility (intraclass correlation coefficient, min. 0.79 for RF, max 0.90 for EF, n = 27). EF and RF scores showed good convergent validity correlating with conceptually similar dimensions of other study scales. Acute and relapsing infections had a significant impact on EF and RF.
CONCLUSIONS:
This study provides evidence of the reliability and construct validity of the CVID_QoL to identify QoL issues in patients with CVID that may not be addressed by generic instruments
Marine spatial planning for connectivity and conservation through ecological corridors between marine protected areas and other effective area-based conservation measures
Maritime Spatial Planning (MSP) promotes the sustainable human activities development and uses in the marine space, playing a role in their effective management. The enhancement of connectivity is crucial for the conservation of biodiversity and landscape planning. Ecological Corridors (ECs) are an important type of connectivity for biodiversity conservation in fragmented habitats. The EU Biodiversity Strategy 2030 includes ECs into the network of protected areas and allows for the creation of additional protected areas. MSP studies considering ECs remain still lacking, especially for the design of networks between Marine Protected Areas (MPAs) and Other Effective area-based Conservation Measures (OECMs). In this paper, knowledge, and tools for investigating marine ECs were reviewed, with a systematic bibliometric analysis to summarize the current scientific research. Previous studies integrating ecological connectivity into planning for marine conservation have focused on models of larval dispersal, adult movements, and dispersal of single species by using benthic habitat proxies. Few studies were found on ECs in marine environments: in the coral Caribbean reef systems in the Gulf of Mexico; within benthic habitats along the Pacific coast of Canada; between MPAs in British Columbia (Canada); and by analyzing migratory species in the Yangtze estuary (China). Commonly used approaches to project and map ECs in marine environments are least-cost and circuit theories allowing to incorporate movement with cost or resistance to movement, depending on species and preferred habitats. The systematic bibliometric analysis returned 25 studies, most of which were from North America (40%) and European countries (36%) and the largest share of papers (68%) from 2018 to 2022. This review pinpointed the need of integrating different disciplines to investigate connectivity and the need by policymakers and practitioners to recognize the importance of ecological connectivity, even there are significant challenges for integrating connectivity into policies, planning, and conservation
Gianni Colombo al Castello di Rivoli, tra fruizione e conservazione
Riflessione riguardante il difficile connubio tra fruizione e conservazione delle opere di Gianni Colombo, artista del Gruppo T la cui peculiarità fu proprio il rapporto "programmato", nel senso di previsto e progettato, con il fruitore dell'opera stessa
Determinants of varicella breakthrough: Results of a 2012 case control study
This study aims to evaluate the determinants of breakthrough infection after one dose of varicella vaccine. We designed a retrospective case-control study. Breakthrough cases were children, aged 1-15, who presented varicella symptoms ≥ 42 days after the first dose of varicella vaccine (breakthrough). Controls were children, aged 1-15 years, who attended the same class (in a school or in a kindergarten) than the cases in the year of the breakthrough onset; they received a dose of varicella vaccine ≥ 42 days before the case rash onset and they did not develop varicella symptoms. We enrolled 45 cases and 135 controls. 40% of cases (n = 18; 95% CI = 25.4-54. 6) presented at least one risk factor; this proportion was 39.2% (95% CI = 30.9-47.6) among the controls (chi-square = 0.0078; P = 0.93). Time between vaccination and virus exposure was longer among cases. Logistic regression showed that breakthrough disease was associated with duration of time from vaccination
Effects of balloon injury on neointimal hyperplasia in steptozotocin-induced diabetes and in hyperinsulinemic nondiabetic pancreatic islet-transplanted rats.
BACKGROUND:
The mechanisms of increased neointimal hyperplasia after coronary interventions in diabetic patients are still unknown.
METHODS AND RESULTS:
Glucose and insulin effects on in vitro vascular smooth muscle cell (VSMC) proliferation and migration were assessed. The effect of balloon injury on neointimal hyperplasia was studied in streptozotocin-induced diabetic rats with or without adjunct insulin therapy. To study the effect of balloon injury in nondiabetic rats with hyperinsulinemia, pancreatic islets were transplanted under the kidney capsule in normal rats. Glucose did not increase VSMC proliferation and migration in vitro. In contrast, insulin induced a significant increase in VSMC proliferation and migration in cell cultures. Furthermore, in VSMC culture, insulin increased MAPK activation. A reduction in neointimal hyperplasia was consistently documented after vascular injury in hyperglycemic streptozotocin-induced diabetic rats. Insulin therapy significantly increased neointimal hyperplasia in these rats. This effect of hyperinsulinemia was totally abolished by transfection on the arterial wall of the N17H-ras-negative mutant gene. Finally, after experimental balloon angioplasty in hyperinsulinemic nondiabetic islet-transplanted rats, a significant increase in neointimal hyperplasia was observed.
CONCLUSIONS:
In rats with streptozotocin-induced diabetes, balloon injury was not associated with an increase in neointimal formation. Exogenous insulin administration in diabetic rats and islet transplantation in nondiabetic rats increased both blood insulin levels and neointimal hyperplasia after balloon injury. Hyperinsulinemia through activation of the ras/MAPK pathway, rather than hyperglycemia per se, seems to be of crucial importance in determining the exaggerated neointimal hyperplasia after balloon angioplasty in diabetic animals
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