236 research outputs found
Development and calibration of a WDXRF routine applied to provenance studies on archaeological ceramics
Elemental analysis of ancient ceramics is primarily used in provenance research,
where defined compositional groups are attributed to particular raw materials sources
or production locations. Requirements in data quality and analytical performance are
high, as is the need for clear and reproducible methodologies, and the availability of
information on the above to ensure interlaboratory comparability and long-term data
validity. This paper outlines the measurement parameters of a dedicated calibration
set-up for the analysis of ancient ceramics using wavelength-dispersive X-ray
fluorescence spectrometry (WDXRF). The specimens are prepared as concentrated
glass beads, allowing the measurement of 26 elements from a single sample, thus
minimising sample size requirements. Certified and non-commercial standards are
used to evaluate the performance of the method in terms of detection limits, precision,
repeatability, and accuracy. The materials used cover a range of compositions in line
with the matrix variability encountered in archaeological ceramics. The data confirm
the high standard of the method and highlight specific limitations. An initial
assessment of comparability with other set-ups used in ceramic analyses, primarily
Neutron Activation Analysis, is given through a discussion of performance on
commonly analysed materials. The advantages of the proposed method include
excellent analytical performance, analysis of a large suite of elements including all
major, minor and a good range of traces, relatively small sample sizes, and
preparation of samples that can be stored and re-analysed
Meeting at the Crossroad between Obesity and Hepatic Carcinogenesis:Unique Pathophysiological Pathways Raise Expectations for Innovative Therapeutic Approaches
Linear dichroism and circular dichroism in photosynthesis research
The efficiency of photosynthetic light energy conversion depends largely on the molecular architecture of the photosynthetic membranes. Linear- and circular-dichroism (LD and CD) studies have contributed significantly to our knowledge of the molecular organization of pigment systems at different levels of complexity, in pigment–protein complexes, supercomplexes, and their macroassemblies, as well as in entire membranes and membrane systems. Many examples show that LD and CD data are in good agreement with structural data; hence, these spectroscopic tools serve as the basis for linking the structure of photosynthetic pigment–protein complexes to steady-state and time-resolved spectroscopy. They are also indispensable for identifying conformations and interactions in native environments, and for monitoring reorganizations during photosynthetic functions, and are important in characterizing reconstituted and artificially constructed systems. This educational review explains, in simple terms, the basic physical principles, and theory and practice of LD and CD spectroscopies and of some related quantities in the areas of differential polarization spectroscopy and microscopy
Curative in vivo hematopoietic stem cell gene therapy of murine thalassemia using large regulatory elements
Recently, we demonstrated that hematopoietic stem/progenitor cell (HSPC) mobilization followed by intravenous injection of integrating, helper-dependent adenovirus HDAd5/35++ vectors resulted in efficient transduction of long-term repopulating cells and disease amelioration in mouse models after in vivo selection of transduced HSPCs. Acute innate toxicity associated with HDAd5/35++ injection was controlled by appropriate prophylaxis, making this approach feasible for clinical translation. Our ultimate goal is to use this technically simple in vivo HSPC transduction approach for gene therapy of thalassemia major or sickle cell disease. A cure of these diseases requires high expression levels of the therapeutic protein (γ- or β-globin), which is difficult to achieve with lentivirus vectors because of their genome size limitation not allowing larger regulatory elements to be accommodated. Here, we capitalized on the 35 kb insert capacity of HDAd5/35++ vectors to demonstrate that transcriptional regulatory regions of the β-globin locus with a total length of 29 kb can efficiently be transferred into HSPCs. The in vivo HSPC transduction resulted in stable γ-globin levels in erythroid cells that conferred a complete cure of murine thalassemia intermedia. Notably, this was achieved with a minimal in vivo HSPC selection regimen
Telling the collective story? Moroccan-Dutch young adults’ negotiation of a collective identity through storytelling
Researchers taking a social constructionist perspective on identity agree that identities are constructed and negotiated in interaction. However, empirical studies in this field are often based on interviewer–interviewee interaction or focus on interactions with members of a socially dominant out-group. How identities are negotiated in interaction with in-group members remains understudied. In this article we use a narrative approach to study identity negotiation among Moroccan-Dutch young adults, who constitute both an ethnic and a religious (Muslim) minority in the Netherlands. Our analysis focuses on the topics that appear in focus group participants’ stories and on participants’ responses to each other’s stories. We find that Moroccan-Dutch young adults collectively narrate their experiences in Dutch society in terms of discrimination and injustice. Firmly grounded in media discourse and popular wisdom, a collective narrative of a disadvantaged minority identity emerges. However, we also find that this identity is not uncontested. We use the concept of second stories to explain how participants negotiate their collective identity by alternating stories in which the collective experience of deprivation is reaffirmed with stories in which challenging or new evaluations of the collective experience are offered. In particular, participants narrate their personal experiences to challenge recurring evaluations of discrimination and injustice. A new collective narrative emerges from this work of joint storytelling
'You give us rangoli, we give you talk': using an art-based activity to elicit data from a seldom heard group
<p>Abstract</p> <p>Background</p> <p>The exclusion from health research of groups most affected by poor health is an issue not only of poor science, but also of ethics and social justice. Even if exclusion is inadvertent and unplanned, policy makers will be uninformed by the data and experiences of these groups. The effect on the allocation of resources is likely to be an exacerbation of health inequalities.</p> <p>Discussion</p> <p>We subject to critical analysis the notion that certain groups, by virtue of sharing a particular identity, are inaccessible to researchers - a phenomenon often problematically referred to as 'hard to reach'. We use the term 'seldom heard' to move the emphasis from a perceived innate characteristic of these groups to a consideration of the methods we choose as researchers. Drawing on a study exploring the intersections of faith, culture, health and food, we describe a process of recruitment, data collection and analysis in which we sought to overcome barriers to participation. As we were interested in the voices of South Asian women, many of whom are largely invisible in public life, we adopted an approach to data collection which was culturally in tune with the women's lives and values. A collaborative activity mirroring food preparation provided a focus for talk and created an environment conducive to data collection. We discuss the importance of what we term 'shoe leather research' which involves visiting the local area, meeting potential gatekeepers, and attending public events in order to develop our profile as researchers in the community. We examine issues of ethics, data quality, management and analysis which were raised by our choice of method.</p> <p>Summary</p> <p>In order to work towards a more theoretical understanding of how material, social and cultural factors are connected and influence each other in ways that have effects on health, researchers must attend to the quality of the data they collect to generate finely grained and contextually relevant findings. This in turn will inform the design of culturally sensitive health care services. To achieve this, researchers need to consider methods of recruitment; the makeup of the research team; issues of gender, faith and culture; and data quality, management and analysis.</p
Safe and efficient in vivo hematopoietic stem cell transduction in nonhuman primates using HDAd5/35++ vectors
We tested a new in vivo hematopoietic stem cell (HSC) transduction/selection approach in rhesus macaques using HSC-tropic, integrating, helper-dependent adenovirus vectors (HDAd5/35++) designed for expression of human γ−globin in red blood cells (RBCs) to treat hemoglobinopathies. We show that HDAd5/35++ vectors preferentially transduce HSCs in vivo after intravenous injection into G-CSF/AMD3100-mobilized animals, and that transduced cells return to the bone marrow and spleen. The approach was well tolerated and activation of proinflammatory cytokines that is usually associated with intravenous adenovirus vector injection, was successfully blunted by pre-treatment with dexamethasone in combination with IL-1 and IL-6 receptor blockers. Using our MGMT(P140K)-based in vivo selection approach, γ-globin(+) RBCs increased in all animals with levels up to 90%. After selection, the percentage of γ-globin(+) RBCs declined most likely due to an immune response against human transgene products. Our biodistribution data indicate that γ-globin(+) RBCs in the periphery were mostly derived from mobilized HSCs that homed to the spleen. Integration site analysis revealed a polyclonal pattern and no genotoxicity related to transgene integrations. This is the first proof-of-concept study in nonhuman primates that in vivo HSC gene therapy could be feasible in humans without the need for high-dose chemotherapy conditioning and HSC transplantation
Impact of environmental and genetic factors on the scale shape of zebrafish, Danio rerio (Hamilton 1822): A geometric morphometric study
Intraspecific morphological variability may reflect either genetic divergence among groups of individuals or response of individuals to environmental circumstances within the frame of phenotypic plasticity. Several studies were able to discriminate wild fish populations based on their scale shape. Here we examine whether the variations in the scale shape in fish populations could be related to genetic or environmental factors, or to both of them. In the first experiment, two inbred lines of zebrafish Danio rerio (Hamilton 1822) reared under identical environmental conditions were compared. Secondly, to find out what effect environmental factors might have, offsprings were divided into two groups and reared on different diets for 12 weeks. Potential recovery of scales from an environmental effect was also assessed. Experimental groups could successfully be distinguished according to the shape of scales in both experiments, and the results showed that both genetic and environmental factors may notably influence scale shape. It was concluded that scale shape analysis might be used as an explanatory tool to detect potential variability of environmental influences impacting genetically homogeneous groups of fish. However, due to its sensitivity to environmental heterogeneity, the applicability of this technique in identifying intraspecific stock membership of fish could be limited
Introduction
Why do parent\u2013child argumentative interactions matter? What is the reason for such an interest? This chapter provides the reasons that motivated the study of parent\u2013child argumentation with the aim to understand the function of this type of interactions. Focusing on the activity of family mealtime, in the first part, the chapter draws attention to the distinctive features of parent\u2013child conversations. A second section of the chapter is devoted to discussing whether and, eventually, when children have the competence to construct arguments and engage in argumentative discussions with the aim to convince their parents to change opinion. In the last part of the chapter, research questions and structure of the volume are presented
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