Modelization of flow electrification in a polymer melt

Flow electrification of polymer melts is an important side effect of polymer processing. The studies dealing with this phenomenon are seldom and most of the scientific work has been focused on flow electrification of aqueous and insulating Newtonian liquids. From that prior art it is well established that the flow electrification in Newtonian liquids is a consequence of the formation of an ionic double layer. Convection of this layer induces the electrification of the liquid at the outlet of the pipe. In those models, the key parameters governing the flow electrification are thus the intrinsic electrical properties of the polymer and the flow characteristics. In this work, we reconsider the assumptions made previously and we propose a new approach to modelise the flow electrification in the particular case of non-Newtonian polymer materials in laminar flow conditions. We establish that, a key parameter for the electrification quantification in the polymer melt is the shape of the velocity profile. Additionally, in some cases, we show that a slip velocity at the polymer/die wall interface must be considered to describe accurately the electrification. As a consequence, we deduce that the slip velocity at the interface can be calculated by measuring the electrification: this work gives an alternative manner to measure the slip velocity during polymer flow

Community perceptions of a malaria vaccine in the Kintampo districts of Ghana.

BACKGROUND: Malaria remains the leading cause of morbidity and mortality in sub-Saharan Africa despite tools currently available for its control. Making malaria vaccine available for routine use will be a major hallmark, but its acceptance by community members and health professionals within the health system could pose considerable challenge as has been found with the introduction of polio vaccinations in parts of West Africa. Some of these challenges may not be expected since decisions people make are many a time driven by a complex myriad of perceptions. This paper reports knowledge and perceptions of community members in the Kintampo area of Ghana where malaria vaccine trials have been ongoing as part of the drive for the first-ever licensed malaria vaccine in the near future. METHODS: Both qualitative and quantitative methods were used in the data collection processes. Women and men whose children were or were not involved in the malaria vaccine trial were invited to participate in focus group discussions (FGDs). Respondents, made up of heads of religious groupings in the study area, health care providers, traditional healers and traditional birth attendants, were also invited to participate in in-depth interviews (IDIs). A cross-sectional survey was conducted in communities where the malaria vaccine trial (Mal 047RTS,S) was carried out. In total, 12 FGDs, 15 IDIs and 466 household head interviews were conducted. RESULTS: Knowledge about vaccines was widespread among participants. Respondents would like their children to be vaccinated against all childhood illnesses including malaria. Knowledge of the long existing routine vaccines was relatively high among respondents compared to hepatitis B and Haemophilus influenza type B vaccines that were introduced more recently in 2002. There was no clear religious belief or sociocultural practice that will serve as a possible barrier to the acceptance of a malaria vaccine. CONCLUSION: With the assumption that a malaria vaccine will be as efficacious as other EPI vaccines, community members in Central Ghana will accept and prefer malaria vaccine to malaria drugs as a malaria control tool. Beliefs and cultural practices as barriers to the acceptance of malaria vaccine were virtually unknown in the communities surveyed

Stabilnost amlodipin besilata i atenolola u jednoslojnim i dvoslojnim tabletama

Multi-drug tablets of amlodipine besylate and atenolol were prepared as either mono-layer (mixed matrix) or bi-layer tablets containing each drug in a separate layer by using similar excipients and processing. Each tablet batch was packed in strip and blister packs and kept under accelerated temperature and humidity conditions. The stability of two tablet and packaging types was compared by HPLC analysis after 0, 1, 3 and 4.5 months and expressed as the content of intact amlodipine and atenolol. The content of atenolol did not decline regardless of tablet and packaging type. Amlodipine content in bi-layer tablets decreased to about 95 and 88% when packed in strips and blisters, respectively. When prepared as mono-layer tablets, the content decreased to 72 and 32%, respectively. The study revealed that the bi-layer tablet formulation was more stable than the mono-layer type. Further, the stability was increased when the tablets were packed in aluminium strips as compared to PVC blisters.Tablete s amlodipinom i atenololom pripremljene su ili u obliku jednoslojne tablete (miješani matriks) ili kao dvoslojne tablete (lijekovi u zasebnim slojevima) koristeći slične pomoćne tvari i uvjete tabletiranja. Tablete su pakirane u dvije vrste pakiranja, aluminijske folije (strip) ili PVC (blister) i čuvane u uvjetima ubrzanog starenja. Stabilnost je određivana pomoću HPLC metode nakon 0, 1, 2, 3 i 4,5 mjeseci i izražena kao sadržaj intaktnog lijeka. Sadržaj atenolola nije se značajno promijenio bez obzira na tip tablete ili pakiranje. Sadržaj amlodipina u dvoslojnim tabletama smanjio se na 95 % (tablete u strip pakiranju) i 88 % (tablete u blister pakiranju). Istodobno, u jednoslojnom tipu kombiniranih tableta sadržaj se smanjio na 72 % (strip pakiranje) i 32 % (blister pakiranje). Rezultati pokazuju da su dvoslojne tablete s amlodipinom i atenololom stabilnije od jednoslojnih. Štoviše, pakiranje tableta u aluminijsku foliju u obliku strip pakiranja povećava njihovu stabilnost u usporedbi s PVC pakirnim materijalom (blister)

Detecting change via competence model

In real world applications, interested concepts are more likely to change rather than remain stable, which is known as concept drift. This situation causes problems on predictions for many learning algorithms including case-base reasoning (CBR). When learning under concept drift, a critical issue is to identify and determine "when" and "how" the concept changes. In this paper, we developed a competence-based empirical distance between case chunks and then proposed a change detection method based on it. As a main contribution of our work, the change detection method provides an approach to measure the distribution change of cases of an infinite domain through finite samples and requires no prior knowledge about the case distribution, which makes it more practical in real world applications. Also, different from many other change detection methods, we not only detect the change of concepts but also quantify and describe this change. © 2010 Springer-Verlag

Primary skin fibroblasts as a model of Parkinson's disease

Parkinson's disease is the second most frequent neurodegenerative disorder. While most cases occur sporadic mutations in a growing number of genes including Parkin (PARK2) and PINK1 (PARK6) have been associated with the disease. Different animal models and cell models like patient skin fibroblasts and recombinant cell lines can be used as model systems for Parkinson's disease. Skin fibroblasts present a system with defined mutations and the cumulative cellular damage of the patients. PINK1 and Parkin genes show relevant expression levels in human fibroblasts and since both genes participate in stress response pathways, we believe fibroblasts advantageous in order to assess, e.g. the effect of stressors. Furthermore, since a bioenergetic deficit underlies early stage Parkinson's disease, while atrophy underlies later stages, the use of primary cells seems preferable over the use of tumor cell lines. The new option to use fibroblast-derived induced pluripotent stem cells redifferentiated into dopaminergic neurons is an additional benefit. However, the use of fibroblast has also some drawbacks. We have investigated PARK6 fibroblasts and they mirror closely the respiratory alterations, the expression profiles, the mitochondrial dynamics pathology and the vulnerability to proteasomal stress that has been documented in other model systems. Fibroblasts from patients with PARK2, PARK6, idiopathic Parkinson's disease, Alzheimer's disease, and spinocerebellar ataxia type 2 demonstrated a distinct and unique mRNA expression pattern of key genes in neurodegeneration. Thus, primary skin fibroblasts are a useful Parkinson's disease model, able to serve as a complement to animal mutants, transformed cell lines and patient tissues

Machine Learning in Automated Text Categorization

The automated categorization (or classification) of texts into predefined categories has witnessed a booming interest in the last ten years, due to the increased availability of documents in digital form and the ensuing need to organize them. In the research community the dominant approach to this problem is based on machine learning techniques: a general inductive process automatically builds a classifier by learning, from a set of preclassified documents, the characteristics of the categories. The advantages of this approach over the knowledge engineering approach (consisting in the manual definition of a classifier by domain experts) are a very good effectiveness, considerable savings in terms of expert manpower, and straightforward portability to different domains. This survey discusses the main approaches to text categorization that fall within the machine learning paradigm. We will discuss in detail issues pertaining to three different problems, namely document representation, classifier construction, and classifier evaluation.Comment: Accepted for publication on ACM Computing Survey

First GIS analysis of modern stone tools used by wild chimpanzees (Pan troglodytes verus) in Bossou, Guinea, West Africa

Stone tool use by wild chimpanzees of West Africa offers a unique opportunity to explore the evolutionary roots of technology during human evolution. However, detailed analyses of chimpanzee stone artifacts are still lacking, thus precluding a comparison with the earliest archaeological record. This paper presents the first systematic study of stone tools used by wild chimpanzees to crack open nuts in Bossou (Guinea-Conakry), and applies pioneering analytical techniques to such artifacts. Automatic morphometric GIS classification enabled to create maps of use wear over the stone tools (anvils, hammers, and hammers/anvils), which were blind tested with GIS spatial analysis of damage patterns identified visually. Our analysis shows that chimpanzee stone tool use wear can be systematized and specific damage patterns discerned, allowing to discriminate between active and passive pounders in lithic assemblages. In summary, our results demonstrate the heuristic potential of combined suites of GIS techniques for the analysis of battered artifacts, and have enabled creating a referential framework of analysis in which wild chimpanzee battered tools can for the first time be directly compared to the early archaeological record.Leverhulme Trust [IN-052]; MEXT [20002001, 24000001]; JSPS-U04-PWS; FCT-Portugal [SFRH/BD/36169/2007]; Wenner-Gren Foundation for Anthropological Researc