Evaluation of the onset of space charge and electroluminescence as a marker for cross linked polyethylene ageing

The aim of the “ARTEMIS” project is to investigate the ageing mechanisms for cross-linked polyethylene under thermo-electrical stress and to identify ageing markers, which can be used to carry out diagnostic procedures. A carefully selected set of techniques which can give cross-correlated information on space charge phenomenology and material degradation were used to investigate specimens peeled from reference and aged cables. The paper shows that ageing induces a change in the density and depth of trapping levels, and an increase in the number and size of mesovoids. Interpretation of these results is discussed in terms of physico-chemical modifications, which can affect trap distribution and microstructure

Fast and slow charge packets in polymeric materials under DC stress

The presence of slow space charge packets crossing the insulation thickness from one electrode to the other and causing significant electrical field distortion has been reported already in several papers. They are activated in general by very high dc fields or, in highly polluted materials, by relatively low fields and constitute an important ageing factor, concerning dc electrical stress. It has been observed, in fact, that such packets can cause accelerated breakdown of insulation. The development of fast systems for space charge measurements has allowed the presence of almost instant heterocharge to be observed close to electrodes in certain field and temperature conditions, especially in cable models. This has been explained often by the separation of ionic charge populations, even though such heterocharge appears also in materials, such as Polyethylene or crosslinked Polyethylene that represent the best extra-clean technologies. The measurements reported here use a high speed technique to investigate the build up of heterocharge in model cables that have been treated to remove volatile chemical species. They show that in fact the heterocharge is built up by many very small and very fast charge packets (i.e. charge packets having a high mobility), which are injected from both electrodes and cross the insulation in less than one second. Because the packet charge is unable to exit the counter-electrode at the same rate at which it arrives, hetero-charge is built up within just a few seconds from the beginning of the polarization. The mobility of these charges, depending significantly on temperature, is estimated through observation of charge packets as a function of time, and compared with that of the already-known slow packets, generally occurring at higher fields with respect to fast packets. The basis for the interpretation and modelling of such phenomena is discussed

Factors associated with inconsistent condom use among HIV-infected patients reporting sex with a main or casual partner(s) - either HIV negative or of unknown status during the first year of antiretroviral therapy in Cameroon: univariate and multivariate analyses using mixed-effect logistic models (212 patients, 344 visits).

<p>OR  =  crude odds ratio, AOR  =  adjusted odds ratio, IQR: interquartile range,</p>*<p>included in multivariate analysis,</p>a<p>during the previous 12 months,</p>b<p>consumption of three big bottles and/or six glasses of alcoholic beverages or more on any one occasion,</p>c<p>level 1 or 2 on a ten-point scale <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036118#pone.0036118-SinghManoux1" target="_blank">[15]</a>,</p>d<p>score range 0–60, higher values denote more depressive symptoms <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036118#pone.0036118-Radloff1" target="_blank">[17]</a>.</p

Overall rate of disclosure over time since initiating ART.

<p>The overall rate of disclosure to different categories of relatives and friends (panel A) and to different members among immediate family (panel B) was calculated at enrolment (M0) and at each follow-up time point (M3, M6, M12, M24) as the percentage of participants having revealed their serostatus to each of the relationship categories.</p

Schedule of enrolment and follow-up visits.

1<p>P: physician-led visit; N: nurse-led visit.</p>2<p>ITW: Follow-up points when face-to-face interviews took place.</p>3<p>Disclosure assessment: Follow-up points considered in the present analysis when disclosure was assessed during face-to-face interviews.</p

Baseline characteristics of participants (N = 385).

<p>Baseline characteristics of participants (N = 385).</p

Factors associated with HIV serostatus disclosure to relatives (Mixed Poisson regression model N = 385).

<p>Factors associated with HIV serostatus disclosure to relatives (Mixed Poisson regression model N = 385).</p

Factors associated with the susceptibility to transmitting HIV during the first 24 months of antiretroviral therapy in Cameroon: univariate and multivariate analyses using mixed-effects logistic models (Stratall ANRS 12110/ESTHER trial, 250 patients, 473 visits).

<p>OR = odds ratio; AOR = adjusted odds ratio; IQR = interquartile range; CLIN = clinical monitoring alone; LAB = clinical and laboratory monitoring.</p><p>^aOR per 10-year increase;</p>b<p>Level 1 or 2 on a ten-point scale;</p>c<p>Level 1 to 5 on a 6-point visual scale;</p>d<p>CES-D score>16.</p><p>+OR per one-symptom addition,</p><p>++OR for an extra 6 months on ART.</p

Cross tabulation between incomplete virological suppression (defined as having had at least one detectable viral load (≥40 copies/ml) during the previous 6 months) and inconsistent condom use at each follow up time point (Stratall ANRS 12110/ESTHER trial, 250 patients, 473 visits).

<p>ICU = Inconsistent condom use; VL = Viral Load.</p>*<p>As viral load suppression was not defined at M0, figures reported at M0 are related to No. (%) of patients having an undetectable Viral Load (HIV RNA <40copies/ml).</p>**<p>As viral load suppression was not defined at M0, figures reported at M0 are related to No. (%) of patients having a detectable Viral Load (HIV RNA≥40copies/ml).</p

Time trend of the proportion of patients with incomplete virological suppression (defined as having had a least one detectable viral load (≥40 copies/ml) during the previous 6 months) over the first 24 months (Stratall ANRS 12110/ESTHER trial, 250 patients, 473 visits).

<p>Time trend of the proportion of patients with incomplete virological suppression (defined as having had a least one detectable viral load (≥40 copies/ml) during the previous 6 months) over the first 24 months (Stratall ANRS 12110/ESTHER trial, 250 patients, 473 visits).</p