Albime triangles and Guy’s favourite elliptic curve

This text discusses triangles with the property that a bisector at one vertex, the median at another, and the altitude at the third vertex are concurrent. It turns out that since the 1930s, such triangles appeared in the problem sections of various journals. We recall their well known relation with points on a certain elliptic curve, and we present an elementary proof of the classical result providing the group structure on the real points of such an elliptic curve. A consequence of this answers a question posed by John P. Hoyt in 1991

Het psychiatrisch prognostisch oordeel : een onderzoek naar de waarde van korte-termijnvoorspellingen in de psychiatrie

Deze studie is gewijd aan een bepaald aspect van het handelen van de psychiater en wel aan diens prognostisch oordeel. In hoofdstuk 1 wordt erop gewezen, dat meer nog dan andere medisch specialisten in de laatste decenniën psychiaters geconfronteerd worden met vele en veelal contradictoire theorieën; de vraag, van welke theorieën zij op welke wijze gebruik maken, is dan ook van een steeds grotere relevantie geworden. Vervolgens wordt uiteengezet hoe deze omstandigheid er onder meer toe heeft geleid dat het psychiatrisch handelen zelve meer tot het eigenlijke object van onderzoek is geworden en dat dit soort onderzoek vooral betrekking heeft gehad op het psychiatrisch beoordelingsvermogen. Van de soorten psychiatrisch oordeel die kunnen worden onderscheiden is het voornamelijk het diagnostisch oordeel geweest, dat is onderzocht. In vergelijking hiermee heeft het prognostisch oordeel van onderzoekerszijde opvallend weinig aandacht ondervonden, terwijl dit toch om zowel practische als theoretische redenen het bestuderen alleszins waard lijkt te zijn. Het doel van de in dit proefschrift beschreven studie is dan ook geweest, door middel van systematisch onderzoek van klinisch psychiatrische predicties enig inzicht te verwerven in de waarde van het psychiatrisch prognostisch oordeel en in de factoren die daarop van invloed zouden kunnen zijn. De bijbehorende vraagstelling luidde: welke is de waarde van het psychiatrisch prognostisch oordeel zoals dit blijkt uit de uitkomst van klinisch psychiatrische voorspellingen over het eerste half jaar na het ontslag en welke factoren zijn op deze waarde van invloed

Nuclear and Mitochondrial DNA Polymorphisms in three parthenogenetic meloidogyne SPP

In order to expand our understanding of the genetics of root-knot nematodes, thevariation in nuclear DNA and mitochondrial DNA in Meloidogyne incognita, M.arenaria and M. javanica was investigated. Despite the obligate mitoticparthenogenetic mode of reproduction, a large number of AFLP polymorphismswere observed among all 16 populations studied. Both UPGMA and principlecoordinate analyses revealed three distinct groups that corresponded with therespective species identities of the 16 populations. M. incognita was geneticallymost distinct. Amplification of 63 bp tandem repeats (TR) in mtDNA from singleindividuals enabled the calculation of diversity measures at three hierarchicallevels: within individuals, among individuals of a single population and amongpopulations. For all three species, the highest diversity was observed withinindividuals explaining 43 to 65% of the total diversity. Many individualscontained more than one mtDNA size variant. M. incognita harboured the mostheteroplasmic individuals and was the most homogenous at the population level.Only 13% of the total diversity was observed among populations, while thisfigure was 35% for M. arenaria. Both TR and AFLP data showed that M.arenaria is the most heterogeneous species. The comparison of the geneticdistances based on AFLPs and mtDNA size variants revealed a significantcorrelation for the six M. arenaria populations, whereas no consistent correlationwas observed for the populations of the other two species

A Symbiont-Independent Endo-1,4-β-Xylanase from the Plant-Parasitic Nematode Meloidogyne incognita

Substituted xylan polymers constitute a major part of the hemicellulose fraction of plant cell walls, especially in monocotyledons. Endo-1,4-β-xylanases (EC 3.2.1.8) are capable of hydrolyzing substituted xylan polymers into fragments of random size. Many herbivorous animals have evolved inti- mate relationships with endosymbionts to exploit their enzyme complexes for the degradation of xylan. Here, we report the first finding of a functional endo-1,4-β-xylanase gene from an animal. The gene (Mi-xyl1) was found in the obligate plant-parasitic root-knot nematode Meloidogyne incognita, and encodes a protein that is classified as a member of glycosyl hydrolase family 5. The expression of Mi-xyl1 is localized in the subventral esophageal gland cells of the nematode. Previous studies have shown that M. incognita has the ability to degrade cellulose and pectic polysaccha - rides in plant cell walls independent of endosymbionts. Including our current data on Mi-xyll, we show that the endogenous enzyme complex in root-knot nematode secretions targets essentially all major cell wall carbohydrates to facili-diffusible fragments cleaved from cell wall polysaccharides may act as elicitors of specific disease resistance responses to invading pathogens and parasites (Boudart et al. 1998)

Overweight and obese adults have low intentions of seeking weight-related care:A cross-sectional survey

Background The prevalence of obesity is growing worldwide. Obesity guidelines recommend increasing the level of weight-related care for persons with elevated levels of weight-related health risk (WRHR). However, there seems to be a discrepancy between need for and use of weight-related care. The primary aim of this study is to examine predisposing factors that may influence readiness to lose weight and intention to use weight-related care in an overweight population. Methods A population-based, cross-sectional survey was conducted. Data were collected using an online self-administered questionnaire sent to a population-representative sample of 1,500 Dutch adults on the Health Care Consumer Panel (n = 861 responded). Data were used from individuals (n = 445) with a mildly, moderately or severely elevated level of WRHR. WRHR status was based on self-reported data on Body Mass Index, risk assessment for diabetes mellitus type 2 (DM2) and cardiovascular disease (CVD), or co-morbidities. Results 55.1% of persons with increased WRHR were ready to lose weight (n = 245). Depending on level of WRHR; educational level, marital status, individuals with an accurate perception of their weight and better perceptions and expectations of dietitians were significantly related to readiness to lose weight. Most of them preferred individual weight-loss methods (82.0% of n = 245). 11% (n = 26 of n = 245) intended to use weight-related care. Weight-related care seeking was higher for those with moderate or severe WRHR. Expectations and trust in dietitians did not seem to influence care seeking. Conclusions Many Dutch adults who are medically in need of weight-related care are ready to lose weight. Most intend to lose weight individually, and only a few intend to use weight-related care. Therefore, obesity prevention initiatives should focus on monitoring weight change and weight-loss plans, and timely referral to obesity management. However, many people are not ready to lose weight. For this group, strategies for behaviour change may depend on WRHR, perceptions of weight and dietitians, educational level and marital status. Obesity prevention initiatives should focus on increasing the awareness of the seriousness of their condition and offering individually appropriate weight management programmes. Keywords: Overweight, Obesity, Weight change, Patient’s acceptance of health care, Perception, Dietary service

Comparative sequence analysis of the potato cyst nematode resistance locus H1 reveals a major lack of co-linearity between three haplotypes in potato (Solanum tuberosum ssp.)

The H1 locus confers resistance to the potato cyst nematode Globodera rostochiensis pathotypes 1 and 4. It is positioned at the distal end of chromosome V of the diploid Solanum tuberosum genotype SH83-92-488 (SH) on an introgression segment derived from S. tuberosum ssp. andigena. Markers from a high-resolution genetic map of the H1 locus (Bakker et al. in Theor Appl Genet 109:146–152, 2004) were used to screen a BAC library to construct a physical map covering a 341-kb region of the resistant haplotype coming from SH. For comparison, physical maps were also generated of the two haplotypes from the diploid susceptible genotype RH89-039-16 (S. tuberosum ssp. tuberosum/S. phureja), spanning syntenic regions of 700 and 319 kb. Gene predictions on the genomic segments resulted in the identification of a large cluster consisting of variable numbers of the CC-NB-LRR type of R genes for each haplotype. Furthermore, the regions were interspersed with numerous transposable elements and genes coding for an extensin-like protein and an amino acid transporter. Comparative analysis revealed a major lack of gene order conservation in the sequences of the three closely related haplotypes. Our data provide insight in the evolutionary mechanisms shaping the H1 locus and will facilitate the map-based cloning of the H1 resistance gene

Word problems versus image-rich problems: an analysis of effects of task characteristics on students’ performance on contextual mathematics problems

This article reports on a post hoc study using a randomised controlled trial with 31,842 students in the Netherlands and an instrument consisting of 21 paired problems. The trial showed a variability in the differences of students’ results in solving contextual mathematical problems with either a descriptive or a depictive representation of the problem situation. In this study the relation between this variability and two task characteristics is investigated: (1) complexity of the task representation; and (2) the content domain of the task. We found indications that differences in performance on descriptive and depictive representations of the problem situation are related to the content domain of the problems. One of the tentative conclusions is that for depicted problems in the domain of measurement and geometry the inferential step from representation of the problem situation to the mathematical problem to be solved is smaller than for word problems