Over de differentiatie van Phytophthora infestans (Mont.) de Bary en de vererving van de resistentie van Solanum demissum Lindl.

In 1943 the breeding work on immunity to blight (Phytophthora infestans) on the Plant Breeding Station of the Central Bureau at Hoofddorp started by using the two races then known in the Netherlands; later 7 new races of Phytophthora were found. The spectra of all known races were investigated and test series composed. The relationships and differences between the races were outlined in schemes.Segregations in the crosses investigated by repeated inoculations with distinct races could be explained by the hypothesis of three genes for immunity. Segregation ratios indicated that these genes were dominant allelomorphs of three independent genes.Other authors postulated genetical factors in explaining their observations. To coordinate the hypotheses test series were exchanged.Although differentiation had been known already for about 25 years the 'new' races were not found on varieties of Solanum tuberosum in practice. This supported the supposition that the 'common' race was superior to the other races on varieties of S. tuberosum.Some specimens of S.demissum and other Solanum spp. were tested for susceptibility to 8 races. There were great differences between the varieties of S. demissum. Some of the progenies of single plants were homozygous for immunity

Скоростные уравнения экситонного лазера

Получены скоростные уравнения экситонного лазера в системе взаимодействующих экситонов и выведены условия инверсной населенности и генерации.Указана принципиально новая возможность создания гамма-лазера.Отримано швидкістні рівняння екситонного лазера в системі взаємодіючих екситонів та виведено умови інверсної населеності, генерації. Показано принципово нову можливість створення гамма-лазераThe rate equations of the exciton laser in the system of interacting excitons have been obtained and the inverted population conditions and generation have been derived. The possibility of creating radically new gamma-ray laser has been shown

Йосиф Конрадович Пачоський: історіографія проблеми

Проаналізовано наукові, науково-популярні, публіцистичні, літературні джерела щодо біографії і наукової діяльності Й.К. Почоського, розділені на три періоди: перший — дореволюційний період вивчення життєвого шляху та наукової діяльності вченого (1882—1917), другий — радянський (1917—1989), третій — сучасний (1989 р.). Окрім вітчизняних, висвітлено праці дослідників із Польщі.Проанализированы научные, научно-популярные, публицистические, литературные источники по биографии и научной деятельности И.К.Пачоского, разделенные на три периода: первый — дореволюционный период изучения жизненного пути и научной деятельности ученого (1882—1917), второй советский (1917—1989), третий — современный (с 1989 г. ). Кроме отечественных, освещены работы исследователей из Польши.The paper contains analysis of scientific, popular-scientific, publicistic and literary sources on the scientific biography of I.K. Pachosky, divided in the three periods: first — pre-revolutionary (1882—1917), second — soviet (1917—1989), third — contemporary (1989 and on). Apart from national scientists, works of scientists from Poland also included

The Role of Personal Demands and Personal Resources in Enhancing Study Engagement and Preventing Study Burnout

Using a 1-year longitudinal design, we examined the role of personal demands and personal resources in long-term health impairment and motivational processes among master students. Based on the job demands-resources theory and transactional model of stress, we hypothesized that students' personal demands (i.e., irrational performance demands, awfulizing and irrational need for control) predict perceived study demands one year later, and indirectly relate to burnout. Furthermore, we predicted that personal resources indirectly associate with study engagement via students' perceived study resources one year later. These hypotheses were tested in a sample of Dutch master students ( N = 220 at T1 and T2) using structural equation modelling. As hypothesized, personal demands and personal resources at T1 predicted study demands and study resources one year later (T2, β = .25-.42, p <. 05), respectively. Study-home interference [study demand] mediated the association between personal demands and burnout (β = .08, p = .029), whereas opportunities for development [study resource] mediated the association between personal resources and study engagement (β = .08, p = .014). Hence, personal demands and personal resources relate indirectly to students' burnout and engagement one year later via a heightened level of specific study demands and study resources. Accordingly, the present research expands the propositions of the JD-R Theory by proposing personal demands as a relevant factor for students' long-term well-being

A simple and rapid flow cytometry-based assay to identify a competent embryo prior to embryo transfer

Multiple pregnancy is a risk for prematurity and preterm birth. The goal of assisted reproduction is to achieve a single pregnancy, by transferring a single embryo. This requires improved methods to identify the competent embryo. Here, we describe such a test, based on flow cytometric determination of the nucleic acid (PI+) containing extracellular vesicle (EV) count in day 5 embryo culture media. 88 women undergoing IVF were included in the study. More than 1 embryos were transferred to most patients. In 58 women, the transfer resulted in clinical pregnancy, whereas in 30 women in implantation failure. In 112 culture media of embryos from the "clinical pregnancy" group, the number of PI+ EVs was significantly lower than in those of 49 embryos, from the "implantation failure" group. In 14 women, transfer of a single embryo resulted in a singleton pregnancy, or, transfer of two embryos in twin pregnancy. The culture media of 19 out of the 20 "confirmed competent" embryos contained a lower level of PI+ EVs than the cut off level, suggesting that the competent embryo can indeed be identified by low PI+ EV counts. We developed a noninvasive, simple, inexpensive, quick test, which identifies the embryos that are most likely to implant

Errors in chromosome segregation during oogenesis and early embryogenesis

Errors in chromosome segregation occurring during human oogenesis and early embryogenesis are very common. Meiotic chromosome development during oogenesis is subdivided into three distinct phases. The crucial events, including meiotic chromosome pairing and recombination, take place from around 11 weeks until birth. Oogenesis is then arrested until ovulation, when the first meiotic division takes place, with the second meiotic division not completed until after fertilization. It is generally accepted that most aneuploid fetal conditions, such as trisomy 21 Down syndrome, are due to maternal chromosome segregation errors. The underlying reasons are not yet fully understood. It is also clear that superimposed on the maternal meiotic chromosome segregation errors, there are a large number of mitotic errors taking place post-zygotically during the first few cell divisions in the embryo. In this chapter, we summarise current knowledge of errors in chromosome segregation during oogenesis and early embryogenesis, with special reference to the clinical implications for successful assisted reproduction

Work engagement in health professions education

Work engagement deserves more attention in health professions education because of its positive relations with personal well-being and performance at work. For health professions education, these outcomes have been studied on various levels. Consider engaged clinical teachers, who are seen as better clinical teachers; consider engaged residents, who report committing fewer medical errors than less engaged peers. Many topics in health professions education can benefit from explicitly including work engagement as an intended outcome such as faculty development programs, feedback provision and teacher recognition. In addition, interventions aimed at strengthening resources could provide teachers with a solid foundation for well-being and performance in all their work roles. Work engagement is conceptually linked to burnout. An important model that underlies both burnout and work engagement literature is the job demands-resources (JD-R) model. This model can be used to describe relationships between work characteristics, personal characteristics and well-being and performance at work. We explain how using this model helps identifying aspects of teaching that foster well-being and how it paves the way for interventions which aim to increase teacher's well-being and performanc

Comparison of DNA methylation patterns of parentally imprinted genes in placenta derived from IVF conceptions in two different culture media

Study question: Is there a difference in DNA methylation status of imprinted genes in placentas derived from IVF conceptions where embryo culture was performed in human tubal fluid (HTF) versus G5 culture medium? Summary answer: We found no statistically significant differences in the mean DNA methylation status of differentially methylated regions (DMRs) associated with parentally imprinted genes in placentas derived from IVF conceptions cultured in HTF versus G5 culture medium. What is known already: Animal studies indicate that the embryo culture environment affects the DNA methylation status of the embryo. In humans, birthweight is known to be affected by the type of embryo culture medium used. The effect of embryo culture media on pregnancy, birth and child development may thus be mediated by differential methylation of parentally imprinted genes in the placenta. Study design, size, duration: To identify differential DNA methylation of imprinted genes in human placenta derived from IVF conceptions exposed to HTF or G5 embryo culture medium, placenta samples (n = 43 for HTF, n = 54 for G5) were collected between 2010 and 2012 s as part of a multi-center randomized controlled trial in the Netherlands comparing these embryo culture media. Placenta samples from 69 naturally conceived (NC) live births were collected during 2008-2013 in the Netherlands as reference material. Participants/materials, setting, methods: To identify differential DNA methylation of imprinted genes, we opted for an amplicon-based sequencing strategy on an Illumina MiSeq sequencing platform. DNA was isolated and 34 DMRs associated with well-defined parentally imprinted genes were amplified in a two-step PCR before sequencing using MiSeq technology. Sequencing data were analyzed in a multivariate fashion to eliminate possible confounding effects. Main results and the role of chance: We found no statistically significant differences in the mean DNA methylation status of any of the imprinted DMRs in placentas derived from IVF conceptions cultured in HTF or G5 culture medium. We also did not observe any differences in the mean methylation status per amplicon nor in the variance in methylation per amplicon between the two culture medium groups. A separate surrogate variable analysis also demonstrated that the IVF culture medium was not associated with the DNA methylation status of these DMRs. The mean methylation level and variance per CpG was equal between HTF and G5 placenta. Additional comparison of DNA methylation status of NC placenta samples revealed no statistically significant differences in mean amplicon and CpG methylation between G5, HTF and NC placenta; however, the number of placenta samples exhibiting outlier methylation levels was higher in IVF placenta compared to NC (P < 0.00001). Also, we were able to identify 37 CpG sites that uniquely displayed outlier methylation in G5 placentas and 32 CpG sites that uniquely displayed outlier methylation in HTF. In 8/37 (G5) and 4/32 (HTF) unique outliers CpGs, a medium-specific unique outlier could be directly correlated to outlier methylation of the entire amplicon. Limitations, reasons for caution: Due to practical reasons, not all placentas were collected during the trial, and we collected the placentas from natural conceptions from a different cohort, potentially creating bias. We limited ourselves to the DNA methylation status of 34 imprinted DMRs, and we studied only the placenta and no other embryo-derived tissues. Wider implications of the findings: It has often been postulated, but has yet to be rigorously tested, that imprinting mediates the effects of embryo culture conditions on pregnancy, birth and child development in humans. Since we did not detect any statistically significant effects of embryo culture conditions on methylation status of imprinted genes in the placenta, this suggests that other unexplored mechanisms may underlie these effects. The biological and clinical relevance of detected outliers with respect to methylation levels of CpGs and DMR require additional analysis in a larger sample size as well. Given the importance and the growing number of children born through IVF, research into these molecular mechanisms is urgently needed. Study funding/competing interest(s): This study was funded by the March of Dimes grant number #6-FY13-153. The authors have no conflicts of interest. Trial registration number: Placental biopsies were obtained under Netherlands Trial Registry number 1979 and 1298

The politicisation of evaluation: constructing and contesting EU policy performance

Although systematic policy evaluation has been conducted for decades and has been growing strongly within the European Union (EU) institutions and in the member states, it remains largely underexplored in political science literatures. Extant work in political science and public policy typically focuses on elements such as agenda setting, policy shaping, decision making, or implementation rather than evaluation. Although individual pieces of research on evaluation in the EU have started to emerge, most often regarding policy “effectiveness” (one criterion among many in evaluation), a more structured approach is currently missing. This special issue aims to address this gap in political science by focusing on four key focal points: evaluation institutions (including rules and cultures), evaluation actors and interests (including competencies, power, roles and tasks), evaluation design (including research methods and theories, and their impact on policy design and legislation), and finally, evaluation purpose and use (including the relationships between discourse and scientific evidence, political attitudes and strategic use). The special issue considers how each of these elements contributes to an evolving governance system in the EU, where evaluation is playing an increasingly important role in decision making