706 research outputs found
Localized and Delocalized Charge Transport in Single-Wall Carbon-Nanotube Mats
We measured the complex dielectric constant in mats of single-wall
carbon-nanotubes between 2.7 K and 300 K up to 0.5 THz. The data are well
understood in a Drude approach with a negligible temperature dependence of the
plasma frequency (omega_p) and scattering time (tau) with an additional
contribution of localized charges. The dielectric properties resemble those of
the best ''metallic'' polypyrroles and polyanilines. The absence of metallic
islands makes the mats a relevant piece in the puzzle of the interpretation of
tau and omega_p in these polymers.Comment: 4 pages including 4 figure
“Четвертий поділ” Польщі і встановлення радянського тоталітарного режиму в Західній Україні
The present article was based on the unknown documents of the Branch state archive of Security service of Ukraine and showed the first phase so called “sovietizashion” (establishment of Soviet regim) of Western Ukraine after being joined to the USSR in the September 1939. The author investigeted the measures used to arrange the 800-meter borderland between the USSR and Third Reich
Dopant-induced crossover from 1D to 3D charge transport in conjugated polymers
The interplay between inter- and intra-chain charge transport in bulk
polythiophene in the hopping regime has been clarified by studying the
conductivity as a function of frequency (up to 3 THz), temperature and doping
level. We present a model which quantitatively explains the observed crossover
from quasi-one-dimensional transport to three-dimensional hopping conduction
with increasing doping level. At high frequencies the conductivity is dominated
by charge transport on one-dimensional conducting chains.Comment: 4 pages, 2 figure
Impact analysis for the purpose of the introduction of DROPLET version 1.3.2
The user-friendly software tool DROPLET (acronym for DRinkwater uit OPpervlaktewater- Landbouwkundig gebruik Evaluatie Tool) assists the Dutch Board for the Authorisation of Plant Protection Products and Biocides (Ctgb) in evaluating whether pesticides may exceed the 0.1 μg/L standard in one of the Dutch surface water abstraction points for drinking water production. Based upon Good Agricultural Practice DROPLET uses the peak concentration in the FOCUS D3 ditch (with spray drift deposition according to Dutch numbers) as starting point for the final, expected concentrations at the abstraction points situated in the larger waterbodies downstream. Results of this impact analysis showed, that for the plant protection products which have been authorized in the period 2014-2018, for which the current version of DROPLET (1.2) was used in the risk assessment, the use of the new DROPLET version (1.3.2.) has no effect on the conclusion for the drinking water criterion. The predicted concentration in surface water at drinking water abstraction points was below the threshold of 0.1 μg/L for all products for all abstraction points for both the old and the new model suite. Therefore, we recommend implementing the new DROPLET version in the national authorization procedure
Diabetic patients detected by population-based stepwise screening already have a diabetic cardiovascular risk profile
OBJECTIVE - To describe a population-based two-step screening procedure for type 2 diabetes and to study the cardiovascular risk profile of the patients identified by the screening. RESEARCH DESIGN AND METHODS - The first step of the screening procedure consisted of the Symptom Risk Questionnaire (SRQ), and the second step was a fasting capillary glucose measurement. In subjects with an SRQ score of >6 and a capillary glucose level of >5.5 mmol/l, an oral glucose tolerance test was performed. RESULTS - A total of 11,679 inhabitants of the West-Friesland region of the Netherlands, aged 50-75 years, were invited. Of the inhabitants, 9,169 (78%) responded, and, of those, 417 had previously diagnosed diabetes. The SRQ score was calculated for 7,736 participants, and 3,301 of those had a score of >6. A total of 2,885 subjects (87.3%) attended for capillary glucose measurement. Diagnostic testing was carried out in 509 participants, and we identified 217 diabetic patients. In these patients detected by screening, mean Hb
The effect of amyloid pathology and glucose metabolism on cortical volume loss over time in Alzheimer’s disease
Purpose: The present multimodal neuroimaging study examined whether amyloid pathology and glucose metabolism are related to cortical volume loss over time in Alzheimer’s disease (AD) patients and healthy elderly controls. Methods: Structural MRI scans of eleven AD patients and ten controls were available at baseline and follow-up (mean interval 2.5 years). Change in brain structure over time was defined as percent change of cortical volume within seven a-priori defined regions that typically show the strongest structural loss in AD. In addition, two PET scans were performed at baseline: [[superscript 11]C]PIB to assess amyloid-β plaque load and [[superscript 18]F]FDG to assess glucose metabolism. [[superscript 11]C]PIB binding and [[superscript 18]F]FDG uptake were measured in the precuneus, a region in which both amyloid deposition and glucose hypometabolism occur early in the course of AD.
Results: While amyloid-β plaque load at baseline was not related to cortical volume loss over time in either group, glucose metabolism within the group of AD patients was significantly related to volume loss over time (rho=0.56, p<0.05).
Conclusion:The present study shows that in a group of AD patients amyloid-β plaque load as measured by [[superscript 11]C]PIB behaves as a trait marker (i.e., all AD patients showed elevated levels of amyloid, not related to subsequent disease course), whilst hypometabolism as measured by [[superscript 18]F]FDG changed over time indicating that it could serve as a state marker that is predictive of neurodegeneration.Hersenstichting Nederland (KS2011(1)-24)Athinoula A. Martinos Center for Biomedical ImagingInternationale Stichting Alzheimer Onderzoek (Project Number 11539
Microvascular complications at time of diagnosis of type 2 diabetes are similar among diabetic patients detected by targeted screening and patients newly diagnosed in general practice - The Hoorn Screening Study
OBJECTIVE - To investigate whether screening-detected diabetic patients differ from diabetic patients newly diagnosed in general practice with regard to the presence of microvascular complications. RESEARCH AND DESIGN METHODS - Diabetic patients, identified by a population-based targeted screening procedure consisting of a screening questionnaire and a fasting capillary whole-blood glucose measurement followed by diagnostic testing, were compared with patients newly diagnosed with diabetes in general practice. Retinopathy was assessed with fundus photography, impaired foot sensitivity was assessed with Semmes-Weinstein monofilaments, and the presence of microalbuminuria was measured by means of the albumin-to creatinine ratio (ACR). RESULTS - A total of 195 screening-detected type 2 diabetic patients and 60 patients newly diagnosed in general practice participated in the medical examination. The prevalence of retinopathy was higher in screening-detected type 2 diabetic patients than in patients newly diagnosed in general practice, but not significantly higher. The prevalence of retinopathy was 7.6% (95% CI 4.6-12.4) in screening-detected type 2 diabetic patients and 1.9% (0.3-9.8) in patients newly diagnosed in general practice. The prevalence of impaired foot sensitivity was similar in both groups, 48.1% (40.9-55.3) and 48.3% (36.2-60.7), respectively. The ACR was 0.61 (interquariile range 0.41-1.50) in screening-detected type 2 diabetic patients and 0.99 (0.53-2.49) in patients newly diagnosed in general practice. The difference in prevalence of microalbuminuria was not statistically significant. The prevalence of microalbuminuria was 17.2% (95% CI 12.5-23.2) and 26.7% (17.1-39.0) in screening-detected type 2 diabetic patients and patients newly diagnosed in general practice, respectively. CONCLUSIONS - Targeted screening for type 2 diabetes (with a screening questionnaire as a first step) resulted in the identification of previously undiagnosed diabetic patients with a considerable prevalence of microvascular complications
Process evaluation of a stepped-care program to prevent depression in primary care: patients' and practice nurses' experiences
Background: Depression is common in patients with diabetes type 2 (DM2) and/or coronary heart disease (CHD), with high personal and societal burden and may even be preventable. Recently, a cluster randomized trial of stepped care to prevent depression among patients with DM2 and/or CHD and subthreshold depression in Dutch primary care (Step-Dep) versus usual care showed no effectiveness. This paper presents its process evaluation, exploring in-depth experiences from a patient and practice nurse perspective to further understand the results. Methods: A qualitative study was conducted. Using a purposive sampling strategy, data were collected through semi-structured interviews with 24 participants (15 patients and nine practice nurses). All interviews were audiotaped and transcribed verbatim. Atlas.ti 5.7.1 software was used for coding and structuring of themes. A thematic analysis of the data was performed. Results: The process evaluation showed, even through a negative trial, that Step-Dep was perceived as valuable by both patients and practice nurses; perceived effectiveness on improving depressive symptoms varied greatly, but most felt that it had been beneficial for patients' well-being. Facilitators were: increased awareness of mental health problems in chronic disease management and improved accessibility and decreased experienced stigma of receiving mental health care. The Patient Health Questionnaire 9 (PHQ-9), used to determine depression severity, functioned as a useful starting point for the conversation on mental health and patients gained more insight into their mental health by regularly filling out the PHQ-9. However, patients and practice nurses did not widely support its use for monitoring depressive symptoms or making treatment decisions. Monitoring mental health was deemed important in chronically ill patients by both patients and practice nurses and was suggested to start at the time of diagnosis of a chronic disease. Appointed barriers were that patients were primarily motivated to participate in scientific research rather than their intrinsic need to improve depressive symptoms. Additionally, various practice nurses preferred offering individually based therapy over pre-determined interventions in a protocolled sequence and somatic practice nurses expressed a lack of competence to recognise and treat mental health problems. Conclusion: This study demonstrates both the benefits and unique demands of programs such as Step-Dep. The appointed facilitators and barriers could guide the development of future studies aiming to prevent depression in similar patient groups
Cerebral perfusion and glucose metabolism in Alzheimer’s disease and frontotemporal dementia: two sides of the same coin?
Significance of Gram's Stain in Rapid Intrapartum Screening for Maternal Carriership of Group B Streptococcus
Objective: Group B streptococcus (GBS, Streptococcus agalactiae) is an important cause of neonatal sepsis. Prevention is possible by intrapartum screening for maternal GBS carriership and antimicrobial treatment of colonized women with risk factors during labor. The conflicting results of diagnostic performance are reported both for the newly developed rapid GBS antigen tests and Gram's stain
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