560 research outputs found
Natural hybridization between Populus nigra L. and P. x canadensis Moench. Hybrid offspring competes for niches along the Rhine river in the Netherlands
Black poplar (Populus nigra L.) is a major species for European riparian forests but its abundance has decreased over the decades due to human influences. For restoration of floodplain woodlands, the remaining black poplar stands may act as source population. A potential problem is that P. nigra and Populus deltoides have contributed to many interspecific hybrids, which have been planted in large numbers. As these Populus x canadensis clones have the possibility to intercross with wild P. nigra trees, their offspring could establish themselves along European rivers. In this study, we have sampled 44 poplar seedlings and young trees that occurred spontaneously along the Rhine river and its tributaries in the Netherlands. Along these rivers, only a few native P. nigra L. populations exist in combination with many planted cultivated P. x canadensis trees. By comparison to reference material from P. nigra, P. deltoides and P. x canadensis, species-specific AFLP bands and microsatellite alleles indicated that nearly half of the sampled trees were not pure P. nigra but progeny of natural hybridisation that had colonised the Rhine river banks. The posterior probability method as implemented in NewHybrids using microsatellite data was the superior method in establishing the most likely parentage. The results of this study indicate that offspring of hybrid cultivated poplars compete for the same ecological niche as native black poplars
Inhibitory control during sentence reading in dyslexic children
The present study focused on the nature of the reading disability of children with the guessing subtype of dyslexia (who read fast and inaccurately). The objective was to separate the excitatory account of their reading disturbance (i.e., in guessers the words' resting levels of activation are oversensitive to semantic context) from the inhibitory account (i.e., guessers tend to react prematurely to (false) candidate words that are activated in the lexicon). To disentangle the above accounts, guessers and normal readers were presented with a sentential priming task (SPT). In the SPT, subjects had to determine whether the final word of a sentence was semantically congruent or incongruent with the sentence, but had to inhibit their 'congruent' or 'incongruent' response in case of an occasionally presented pseudoword. To evoke guessing, each pseudoword closely resembled either a valid congruent or incongruent word. Guessing referred to prematurely accepting a pseudoword as a word that either appropriately or inappropriately completed the sentence. The extent to which subjects guessed at word meaning was evidenced by the false recognition rates (FRR) of the misspelled terminal words. Analyses on the FRRs of the pseudowords showed that guessers had significantly more difficulty in suppressing the 'go tendency' triggered by the pseudowords. It was concluded that the impulsive reading style of guessers should be ascribed to a less efficient suppression mechanism rather than to excessive reliance on contextual information. Specifically, the data were explained by assuming that the availability of the pseudoword's candidate meaning activated the hand to respond with, and that guessers found difficulty in suspending this response until they analyzed all letters in the stimulus and they could be sure of its spelling
Model method drawing acts as a double-edged sword for solving inconsistent word problems
Drawing bar diagrams has been shown to improve performance on mathematical word problems wherein the relational keyword is consistent with the required arithmetic operation. This study extends this by testing the effectiveness of bar diagram drawing for word problems with an inconsistent keyword-arithmetic operation mapping. Seventy-five fifth graders solved consistent and inconsistent word problems while encouraged to draw bar diagrams. For each word problem, we assessed problem type (consistent/inconsistent), performance (correct/incorrect), and bar diagrams (accurate/inaccurate/no drawing). Overall, bar diagram drawing was associated with increased performance on both consistent and inconsistent word problems, but the strongest benefits of drawing were found for inconsistent word problems. For inconsistent word problems, bar diagram accuracy was more clearly related to performance (accurate bar diagrams related to correct answers, but inaccurate ones to incorrect answers) than for consistent word problems. We conclude that bar diagram drawing provides an effective graphical support for solving inconsistent word problems
Dynamical Landau-de Gennes Theory for Electrically-Responsive Liquid Crystal Networks
Liquid crystal networks combine the orientational order of liquid crystals
with the elastic properties of polymer networks, leading to a vast application
potential in the field of responsive coatings, e.g., for haptic feedback,
self-cleaning surfaces and static and dynamic pattern formation. Recent
experimental work has further paved the way toward such applications by
realizing the fast and reversible surface modulation of a liquid crystal
network coating upon in-plane actuation with an AC electric field. Here, we
construct a Landau-type theory for electrically-responsive liquid crystal
networks and perform Molecular Dynamics simulations to explain the findings of
these experiments and inform on rational design strategies. Qualitatively, the
theory agrees with our simulations and reproduces the salient experimental
features. We also provide a set of testable predictions: the aspect ratio of
the nematogens, their initial orientational order when cross-linked into the
polymer network and the cross-linking fraction of the network all increase the
plasticization time required for the film to macroscopically deform. We
demonstrate that the dynamic response to oscillating electric fields is
characterized by two resonances, which can likewise be influenced by varying
these parameters, providing an experimental handle to fine-tune device design
Indicatie genetische variatie hoofdrassen paprika ten behoeve van verbetering uniformiteit : verslag van een pilot-studie
Morfologisch vertonen paprikarassen bij telers soms een gebrek aan uniformiteit. Dit kan een effect zijn van milieuomstandigheden, maar zou (deels) het gevolg kunnen zijn van genetische variatie in de rassen. In het laatste geval zou men de uniformiteit binnen een paprika-ras kunnen verhogen door weefselkweek. Doel van deze korte studie was om vast te stellen of genetische variatie kan worden vastgesteld in paprikarassen met behulp van DNA fingerprint-technieken. Het is een pilot studie, met kleine aantallen bemonsterde planten, zodat het percentage afwijkende planten niet exact kan worden bepaald
Effects of oncologic rehabilitation during adjuvant endocrine therapy in overweight or obese patients with breast cancer
Disentangling genetic and non-genetic components of yield trends of Dutch forage crops in the Netherlands
Grass and forage maize are important forage crops in ruminant production systems in the temperate regions in northwest Europe. High yields of these crops contribute to farm profitability and local provision of feed, and hence local circularity of biomass and nutrients. Variety choice is an important option to raise potential and actual yields. We analysed 40 years of perennial ryegrass and 25 years of forage maize yield data from Value of Culture and Use (VCU) experiments to determine genetic and non-genetic trends of yields in time. For maize, we calculated an annual genetic trend of +173 kg DM ha−1 and a non-genetic trend of +65 kg DM ha−1. Further analysis of the non-genetic trend showed that maize yields increased with increasing temperature sum during the growing season, and with earlier sowing. The feeding value of forage maize showed a genetic trend of +1.7 feed unit milk (VEM) kg DM−1 year−1. The annual genetic gain of perennial ryegrass was +44 kg DM ha−1. In the grass trials we found opposing non-genetic trends for cutting and grazing. Further analysis of the non-genetic trend showed that drought and the number of days with ground frost during the growing season had a negative effect on yield. We compared the average yields and trends in VCU trials with those of on-farm yields. The on-farm maize yields showed an annual trend of +195 kg DM ha−1. We estimated an average realisation of the genetic gains of 75 % in farming practice, implying a widening gap between genetic potential and on-farm yields. Averaged over the entire period, on-farm maize yields were 4.6 t DM ha−1 (24%) lower than the yields of the VCU trials. The average annual on-farm grass yields did not show any trend, and were 1.6 t DM ha−1 (13%) lower than the yields of the VCU trials. In conclusion, our study revealed significant positive genetic and varying non-genetic trends in DM yields of forage maize and perennial ryegrass, the two dominant forage crops in the Netherlands. On-farm yields showed significant positive trends for forage maize, but no trend for grassland.</p
Evaluating The Effectiveness of the Texas Medicaid First Dental Home Program Regarding Parental Knowledge and Practice of Oral Health Care for Children
Early childhood caries (ECC) is a problematic disease that has been on the rise in young pre-school age children within the last decade. Children who have untreated dental disease early in life, are at increased risk of having poor oral health throughout their lifetimes. Approximately 70% of dental disease is found in only 20% of the nation’s high-risk children. Professional organizations and governing bodies have formed several initiatives in order to help lower the prevalence of ECC in children. One such initiative, early preventive dental visits, i.e. dental home, has proven to be successful; yet, the evidence is limited in documenting its effectiveness.
First Dental Home (FDH) is the state of Texas Medicaid initiative to improve access to care for children. FDH was initiated to improve oral healthcare for children aged 6 months to 35 months of age by providing simple, consistent messages regarding proper oral healthcare to the parents/caregivers of the children. Despite the large fiscal budget allocated towards the success of FDH, no studies regarding the program’s effectiveness have been published to date. This study aimed to evaluate the effectiveness of the FDH by comparing the knowledge, practice and opinions of participating vs. non-participating parents regarding their young children. A 29-question survey was given to mostly low-income parents who visited qualifying Medicaid clinics in North Texas (Dallas/Fort Worth) and South Texas (Harlingen). A total of 165 parents completed the survey. Several significant results emerged between the knowledge and practices responses of the parents sampled. On the knowledge section, FDH parents responded correctly more often than the non-FDH parents when asked about the recommended amount of toothpaste recommended for toddlers (p=0.023). In addition, 79.6% of FDH parents vs. 21.1% of non-FDH parents knew that tap water is a potential source of fluoride (p< 0.001). Regarding oral health practices, 80 % of FDH parents did not let their child go to sleep with anything such as a bottle, sippy cup or pacifier (p=0.01). Furthermore, FDH parents scored higher on the overall knowledge score (p<0.001) and practice score (p<0.001). Based on our preliminary findings, FDH visits are having a positive impact on parents by not only increasing their oral healthcare knowledge, but also helping them implement what they have learned
A multicentre double-blinded randomized controlled trial on the efficacy of laser-assisted hatching in patients with repeated implantation failure undergoing IVF or ICSI
STUDY QUESTION: Does assisted hatching increase the cumulative live birth rate in subfertile couples with repeated implantation failure? SUMMARY ANSWER: This study showed no evidence of effect for assisted hatching as an add-on in subfertile couples with repeated implantation failure. WHAT IS KNOWN ALREADY: The efficacy of assisted hatching, with regard to the live birth rate has not been convincingly demonstrated in randomized trials nor meta-analyses. It is suggested though that especially poor prognosis women, e.g. women with repeated implantation failure, might benefit most from assisted hatching. STUDY DESIGN, SIZE, DURATION: The study was designed as a double-blinded, multicentre randomized controlled superiority trial. In order to demonstrate a statistically significant absolute increase in live birth rate of 10% after assisted hatching, 294 participants needed to be included per treatment arm, being a total of 588 subfertile couples. Participants were included and randomized from November 2012 until November 2017, 297 were allocated to the assisted hatching arm of the study and 295 to the control arm. Block randomization in blocks of 20 participants was applied and randomization was concealed from participants, treating physicians, and laboratory staff involved in the embryo transfer procedure. Ovarian hyperstimulation, oocyte retrieval, laboratory procedures, embryo selection for transfer and cryopreservation, the transfer itself, and luteal support were performed according to local protocols and were identical in both the intervention and control arm of the study with the exception of the assisted hatching procedure which was only performed in the intervention group. The laboratory staff performing the assisted hatching procedure was not involved in the embryo transfer itself. PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were eligible for inclusion in the study after having had either at least two consecutive fresh IVF or ICSI embryo transfers, including the transfer of frozen and thawed embryos originating from those fresh cycles, and which did not result in a pregnancy or as having had at least one fresh IVF or ICSI transfer and at least two frozen embryo transfers with embryos originating from that fresh cycle which did not result in a pregnancy. The study was performed at the laboratory sites of three tertiary referral hospitals and two university medical centres in the Netherlands. MAIN RESULTS AND THE ROLE OF CHANCE: The cumulative live birth rate per started cycle, including the transfer of fresh and subsequent frozen/thawed embryos if applicable, resulted in 77 live births in the assisted hatching group (n = 297, 25.9%) and 68 live births in the control group (n = 295, 23.1%). This proved to be statistically not significantly different (relative risk: 1.125, 95% CI: 0.847 to 1.494, P = 0.416). LIMITATIONS, REASONS FOR CAUTION: There was a small cohort of subfertile couples that after not achieving an ongoing pregnancy, still had cryopreserved embryos in storage at the endpoint of the trial, i.e. 1 year after the last randomization. It cannot be excluded that the future transfer of these frozen/thawed embryos increases the cumulative live birth rate in either or both study arms. Next, at the start of this study, there was no international consensus on the definition of repeated implantation failure. Therefore, it cannot be excluded that assisted hatching might be effective in higher order repeated implantation failures. WIDER IMPLICATIONS OF THE FINDINGS: This study demonstrated no evidence of a statistically significant effect for assisted hatching by increasing live birth rates in subfertile couples with repeated implantation failure, i.e. the couples which, based on meta-analyses, are suggested to benefit most from assisted hatching. It is therefore suggested that assisted hatching should only be offered if information on the absence of evidence of effect is provided, at no extra costs and preferably only in the setting of a clinical trial taking cost-effectiveness into account.None. TRIAL REGISTRATION NUMBER: Netherlands Trial Register (NTR 3387, NL 3235, https://www.clinicaltrialregister.nl/nl/trial/26138). TRIAL REGISTRATION DATE: 6 April 2012. DATE OF FIRST PATIENT’S ENROLMENT: 28 November 2012.</p
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