417 research outputs found
Parameter estimation bias of dichotomous logistic item response theory models using different variables
The aim of this study was to examine the precision of item parameter estimation in different sample sizes and test lengths under three parameter logistic model (3PL) item response theory (IRT) model, where the trait measured by a test was not normally distributed or had a skewed distribution.In the study, number of categories (1-0), and item response model were identified as fixed conditions, and sample size, test length variables, and the ability distributions were selected as manipulated conditions. This is a simulation study. So data simulation and data analysis were done via packages in the R programming language. Results of the study showed that item parameter estimations performed under normal distribution were much stronger and bias-free compared to non-normal distribution. Moreover, the sample size had some limited positive effect on parameter estimation. However, the test length had no effect parameter estimation. As a result the importance of normality assumptions for IRT models were highlighted and findings were discussed based on relevant literature
The role of traditional livelihood practices and local ethnobotanical knowledge in mitigating chestnut disease and pest severity in Turkey
The European chestnut population is enduring multiple compounding exotic pest and disease outbreaks across Turkey. The deeply held value of the chestnut species for the Turkish public is reflected in substantial government conservation programming. Chestnut is predominantly found on state land managed by Turkey’s General Directorate of Forestry (GDF), which generally upholds restrictive policies for chestnut-related livelihood practices other than nut collection and beehive placement. Such policies are justified by a government position that human activities and presence is likely to worsen disease dynamics. Conversely, a growing body of research findings testify that small-scale livelihood practices maintain biological diversity and, furthermore, that this traditional maintenance of diversity has been correlated with decreased pathogen pressure within agroecosystems. However, few studies have investigated this phenomenon in the context of agroforestry systems. At a global ecological moment of increasingly pervasive and severe exotic forest pathogen impact, this paper investigates the influence of diverse small-scale livelihood practices and knowledge on chestnut tree health across the highly heterogenous geography of Turkey. We conducted ethnobotanical questionnaires with 96 chestnut-utilizing households, and chestnut tree health evaluations in georeferenced forest areas they identified, throughout Turkey’s Black Sea, Marmara, and Aegean regions. Using data from 1500 trees, we characterized the effects of subsequently recorded environmental, physiological, and anthropogenic factors on tree health using multiple correspondence analysis (MCA), multiple factor analysis (MFA), and mixed models. Our results show that the traditional human management of tree physiology and ecology has a significant positive effect on tree health, especially through the acts of grafting and culling as well as the maintenance of diversity. We argue that conceptualizing such livelihood systems as human niche construction and maintenance can help forest management agencies to better understand and conserve valuable landscapes, even in increasingly common periods of severe pathogenic pressure
Morphology and Oxygen Sensor Response of Luminescent Ir-Labeled Poly(dimethylsiloxane)/Polystyrene Polymer Blend Films
Polymer films consisting of a linear poly(dimethylsiloxane) end-functionalized with a luminescent Ir(III) complex (Ir−PDMS), blended with polystyrene (PS), function as optical oxygen sensors. The sensor response arises by quenching of the luminescence from the Ir(III) chromophore by oxygen that permeates into the polymer film. The morphology and luminescence oxygen sensor properties of blend films consisting of Ir−PDMS and PS have been characterized by fluorescence microscopy, atomic force microscopy, and scanning electron microscopy. The investigations demonstrate that microscale phase segregation occurs in the films. In blends that contain a relatively small amount of Ir−PDMS in PS (ca. 10 wt %), the Ir−PDMS exists as circular domains, with diameters ranging from 2 to 5 μm, surrounded by the majority PS phase. For larger weight fractions of Ir−PDMS in the blends, the film morphology becomes bicontinuous. A novel epifluorescence microscopy method is applied that allows the construction of Stern−Volmer quenching images that quantify the oxygen sensor response of the blend films with micrometer spatial resolution. These images provide a map of the oxygen permeability of the polymer blend films with a spatial resolution of ca. 1 μm. The results of this investigation show that the micrometer-sized Ir−PMDS domains display a 2−3-fold higher oxygen sensor response compared to the surrounding PS matrix. This result is consistent with the fact that PDMS is considerably more gas permeable compared to PS. The relationship of the microscale morphology of the blends to their performance as macroscale optical oxygen sensors is discussed
The IL-25/ILC2 axis promotes lung cancer with a concomitant accumulation of immune-suppressive cells in tumors in humans and mice
Background: Group 2 innate lymphoid cells (ILC2) can be activated by interleukin (IL)-33 or IL-25. IL-25-activated ILC2 cells help protect the host against helminth infection while exacerbating allergic-like inflammation and tissue damage in the lung. In the context of cancer, IL-33-activated ILC2 cells were found to bear anti-tumoral functions in lung cancer while IL-25-activated ILC2 cells promoted tumorigenesis in colorectal cancer. The role of IL-25-activated ILC2 cells in lung cancer remains to be addressed. Methods: We examined the overall survival of human non-small cell lung cancer (NSCLC) patients according to IL25 expression as well as the distribution of ILC2 cells and regulatory T cells (Tregs) in various NSCLC patient tissues and peripheral blood (PB) of healthy donors (HDs). We analyzed the effect of adoptive transfer of IL-25-activated ILC2 cells on tumor growth, metastasis and survival in a heterotopic murine model of lung cancer. Results: We report that human NSCLC patients with high IL-25 expression have reduced overall survival. Moreover, NSCLC patients bear increased frequencies of ILC2s compared to HDs. Frequencies of Tregs were also increased in NSCLC patients, concomitantly with ILC2s. In mice bearing heterotopic lung cancer, adoptive transfer of IL-25-activated ILC2s led to increased tumor growth, increased metastasis and reduced survival. The frequencies of monocytic myeloid-derived suppressor cells (M-MDSCs) were found to be increased in the tumors of mice that received ILC2s as compared to controls. Conclusion: Overall, our results indicate that the IL-25/ILC2 axis promotes lung cancer potentially by recruiting immune-suppressive cells to the tumors both in humans and in mice, and that it may therefore represent a suitable novel target for NSCLC immunotherapeutic development
The Technical and Financial Effects of Parenteral Supplementation with Selenium and Vitamin E during Late Pregnancy and the Early Lactation Period on the Productivity of Dairy Cattle
This study aimed to determine the effects of parenteral selenium (Se) and vitamin E supplementation on economic impact, milk yield, and some reproductive parameters in high-yield dairy cows in the dry period and in those at the beginning of lactation. At the beginning of the dry period, cows (n = 323) were randomly divided into three groups as follows: Treatment 1 (T1), Treatment 2 (T2), and Control (C). Cows in group T1 received this preparation 21 days before calving and on calving day, and cows in group T2 received it only on calving day. The cows in the control group did not receive this preparation. Supplementation with Se increased Se serum levels of cows treated at calving day (p<0.05). Differences in milk yield at all weeks and the electrical conductivity values at the 8th and 12th weeks were significant (p<0.05). Supplementation with Se and Vitamin E decreased the incidence of metritis, the number of services per conception and the service period, but had no effects on the incidence of retained fetal membrane. A partial budgeting analysis indicated that Se supplementation was economically profitable; cows in group T1 averaged 240.6 per cow. Supplementation with Se and Vitamin E has been found to increase serum Se levels, milk yield, and has positive effects on udder health by decreasing milk conductivity values and incidence of sub-clinical mastitis
Image Classification for Age-related Macular Degeneration Screening Using Hierarchical Image Decompositions and Graph Mining
Age-related Macular Degeneration (AMD) is the most common cause of adult blindness in the developed world. This paper describes a new image mining technique to perform automated detection of AMD from color fundus photographs. The technique comprises a novel hierarchical image decomposition mechanism founded on a circular and angular partitioning. The resulting decomposition is then stored in a tree structure to which a weighted frequent sub-tree mining algorithm is applied. The identified sub-graphs are then incorporated into a feature vector representation (one vector per image) to which classification techniques can be applied. The results show that the proposed approach performs both efficiently and accurately
Presentation and management of keloid scarring following median sternotomy: a case study
<p>Abstract</p> <p>Introduction</p> <p>Keloid scars following median sternotomy are rare and occur more frequently in pigmented skin. Different management strategies have been described with variable success. We present a case of keloid scar formation following cardiac surgery including our management and the final aesthetic result.</p> <p>Case description</p> <p>A 64 year old female of fair complexion underwent mitral valve replacement. The procedure and postoperative recovery were uncomplicated, however, during the following year, thick keloid scars formed over the incision sites. Initial non surgical measures failed to relieve pain and did not offer any tangible aesthetic benefit. Eventually surgical excision was attempted. She presented to our clinic for nine months follow up with significant improvement in pain and aesthetic result.</p> <p>Discussion and Evaluation</p> <p>Several theories have attempted to explore the pathophysiology of keloid scar formation. A number of predisposing factors have been documented however none existed in this case. A variety of invasive and non invasive approaches have been described but significant differences in success rates and methodology of investigations still precludes a standardized management protocol.</p> <p>Conclusions</p> <p>In this case study a rare presentation of keloid scar has been presented. The variety of methods used to improve pain and aesthetic result demonstrates the propensity of keloid scars to recur and the therapeutic challenges that surgeons have to face in their quest for a satisfactory patient outcome.</p
Old World megadroughts and pluvials during the Common Era
Climate model projections suggest widespread drying in the Mediterranean Basin and wetting in Fennoscandia in the coming decades largely as a consequence of greenhouse gas forcing of climate. To place these and other “Old World” climate projections into historical perspective based on more complete estimates of natural hydroclimatic variability, we have developed the “Old World Drought Atlas” (OWDA), a set of year-to-year maps of tree-ring reconstructed summer wetness and dryness over Europe and the Mediterranean Basin during the Common Era. The OWDA matches historical accounts of severe drought and wetness with a spatial completeness not previously available. In addition, megadroughts reconstructed over north-central Europe in the 11th and mid-15th centuries reinforce other evidence from North America and Asia that droughts were more severe, extensive, and prolonged over Northern Hemisphere land areas before the 20th century, with an inadequate understanding of their causes. The OWDA provides new data to determine the causes of Old World drought and wetness and attribute past climate variability to forced and/or internal variability
Charged-Particle Multiplicities in Charged-Current Neutrino-- and Anti-Neutrino--Nucleus Interactions
The CHORUS experiment, designed to search for
oscillations, consists of a nuclear emulsion target and electronic detectors.
In this paper, results on the production of charged particles in a small sample
of charged-current neutrino-- and anti-neutrino--nucleus interactions at high
energy are presented. For each event, the emission angle and the ionization
features of the charged particles produced in the interaction are recorded,
while the standard kinematic variables are reconstructed using the electronic
detectors. The average multiplicities for charged tracks, the pseudo-rapidity
distributions, the dispersion in the multiplicity of charged particles and the
KNO scaling are studied in different kinematical regions. A study of
quasi-elastic topologies performed for the first time in nuclear emulsions is
also reported. The results are presented in a form suitable for use in the
validation of Monte Carlo generators of neutrino--nucleus interactions.Comment: 17 pages, 5 figure
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