Минимальные массы проб для анализа показателей качества сырья

Запропоновано методику пошуку мінімальної маси проби для аналізу функцій розподілу збагачувальних показників корисної копалини. На підставі розглянутої методики отримані формули, що визначають мінімальну масу проби у залежності від параметрів підготовки проби.Предложена методика поиска минимальной массы пробы для анализа функций распределения обогатительных показателей полезного ископаемого. На основании рассмотренной методики получены формулы, определяющие минимальную массу пробы в зависимости от параметров подготовки пробы.The technique of the minimum sample mass searching for the analysis of the distribution functions of mineral dressing factors was proposed. Based on the examined methods there were obtained formulas that determined the minimum sample mass as a function of the sample preparation parameters

Is amino acid racemization a useful tool for screening for ancient DNA in bone?

Many rare and valuable ancient specimens now carry the scars of ancient DNA research, as questions of population genetics and phylogeography require larger sample sets. This fuels the demand for reliable techniques to screen for DNA preservation prior to destructive sampling. Only one such technique has been widely adopted: the extent of aspartic acid racemization (AAR). The kinetics of AAR are believed to be similar to the rate of DNA depurination and therefore a good measure of the likelihood of DNA survival. Moreover, AAR analysis is only minimally destructive. We report the first comprehensive test of AAR using 91 bone and teeth samples from temperate and high-latitude sites that were analysed for DNA. While the AAR range of all specimens was low (0.02-0.17), no correlation was found between the extent of AAR and DNA amplification success. Additional heating experiments and surveys of the literature indicated that d/l Asx is low in bones until almost all the collagen is lost. This is because aspartic acid is retained in the bone within the constrained environment of the collagen triple helix, where it cannot racemize for steric reasons. Only if the helix denatures to soluble gelatin can Asx racemize readily, but this soluble gelatine is readily lost in most burial environments. We conclude that Asx d/l is not a useful screening technique for ancient DNA from bone

Development and evaluation of a questionnaire to measure the perceived implementation of the mission statement of a competency based curriculum

BACKGROUND: A mission statement (MS) sets out the long-term goals of an institution and is supposed to be suited for studying learning environments. Yet, hardly any study has tested this issue so far. The aim of the present study was the development and psychometric evaluation of an MS-Questionnaire (MSQ) focusing on explicit competencies. We investigated to what extent the MSQ captures the construct of learning environment and how well a faculty is following - in its perception - a competency orientation in a competency-based curriculum. METHODS: A questionnaire was derived from the MS “teaching” (Medical Faculty, Heinrich-Heine University Düsseldorf) which was based on (inter-) nationally accepted goals and recommendations for a competency based medical education. The MSQ was administered together with the Dundee Ready Education Environment Measure (DREEM) to 1119 students and 258 teachers. Cronbach’s alpha was used to analyze the internal consistency of the items. Explorative factor analyses were performed to analyze homogeneity of the items within subscales and factorial validity of the MSQ. Item discrimination was assessed by means of part-whole corrected discrimination indices, and convergent validity was analyzed with respect to DREEM. Demographic variations of the respondents were used to analyze the inter-group variations in their responses. RESULTS: Students and teachers perceived the MS implementation as “moderate” and on average, students differed significantly in their perception of the MS. They thought implementation of the MS was less successful than faculty did. Women had a more positive perception of educational climate than their male colleagues and clinical students perceived the implementation of the MS on all dimensions significantly worse than preclinical students. The psychometric properties of the MSQ were very satisfactory: Item discrimination was high. Similarly to DREEM, the MSQ was highly reliable among students (α = 0.92) and teachers (α = 0.93). In both groups, the MSQ correlated highly positively with DREEM (r = 0.79 and 0.80, p < 0.001 each). Factor analyses did not reproduce the three areas of the MS perfectly. The subscales, however, could be identified as such both among teachers and students. CONCLUSIONS: The perceived implementation of faculty-specific goals can be measured in an institution to some considerable extent by means of a questionnaire developed on the basis of the institution’s MS. Our MSQ provides a reliable instrument to measure the learning climate with a strong focus on competencies which are increasingly considered crucial in medical education. The questionnaire thus offers additional information beyond the DREEM. Our site-specific results imply that our own faculty is not yet fully living up to its competency-based MS. In general, the MSQ might prove useful for faculty development to the increasing number of faculties seeking to measure their perceived competency orientation in a competency-based curriculum

Is amino acid racemization a useful tool for screening for ancient DNA in bone?

Many rare and valuable ancient specimens now carry the scars of ancient DNA research, as questions of population genetics and phylogeography require larger sample sets. This fuels the demand for reliable techniques to screen for DNA preservation prior to destructive sampling. Only one such technique has been widely adopted: the extent of aspartic acid racemization (AAR). The kinetics of AAR are believed to be similar to the rate of DNA depurination and therefore a good measure of the likelihood of DNA survival. Moreover, AAR analysis is only minimally destructive. We report the first comprehensive test of AAR using 91 bone and teeth samples from temperate and high-latitude sites that were analysed for DNA. While the AAR range of all specimens was low (0.02 -0.17), no correlation was found between the extent of AAR and DNA amplification success. Additional heating experiments and surveys of the literature indicated that D/L Asx is low in bones until almost all the collagen is lost. This is because aspartic acid is retained in the bone within the constrained environment of the collagen triple helix, where it cannot racemize for steric reasons. Only if the helix denatures to soluble gelatin can Asx racemize readily, but this soluble gelatine is readily lost in most burial environments. We conclude that Asx D/L is not a useful screening technique for ancient DNA from bone

Medical care for people affected by torture: training concerning torture and its sequels are important but structural challenges remain unsolved

Torture exists worldwide, for example in countries from which people flee to Germany to seek asylum. People who have experienced torture represent a vulnerable group and are in need of adequate care. The healthcare system plays a central role when it comes to the identification of people affected by torture, this is especially true for medical personnel working in accommodation facilities for refugees; however, identifying people affected by torture is challenging. Aim of this study was therefore to examine if training concerning torture and its consequences enhances confidence and security of medical personnel when dealing with persons who have experienced torture, how medical personnel assess their own role regarding the care of persons with torture experience and which problems and difficulties are seen. The training carried out was evaluated quantitatively as well as qualitatively. Based on questionnaires we evaluated if the training had an effect on security of action of the medical personnel in general and physicians in particular when handling patients with a torture history. Furthermore, the training participants answered reflective questions concerning the applicability of the training content, their own understanding of their role and existing problems and difficulties. After attending the training, the medical personnel in general felt more secure with regard to patients with torture experience; however, this did not apply for participating physicians. Their own role regarding the care for patients with torture experience was rated as important; however, both the quantitative and the qualitative evaluation revealed that the participants experienced major problems and difficulties in their daily routine that require structural and political solutions

The human intervertebral disc as a source of DNA for molecular identification

Genetic analyses such as STR-typing are routinely used for identification purposes in forensic casework. Although genotyping techniques only require a minimum amount of DNA to provide a genetic profile, DNA quality differs not only between but also within tissues during ongoing decomposition. Initiated by a recent case where, due to the constitution of the body, preferred tissue was not available or only resulted in a partial and not usable DNA profile, the analysis of intervertebral discs as a source of DNA was considered. As the analysis of this tissue resulted in a high quality DNA profile a further study was performed in which thirty intervertebral discs dissected from bodies in different stages of decay were analyzed. All samples yielded good quality DNA in quantities suitable for STR-based amplification with no or only low degradation indices, resulting in complete genetic profiles. These results demonstrate the robustness of human intervertebral disc tissue as a source of DNA for molecular identification purposes