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Search Results: 1 - 10 of 361631 matches for " L. G. Hansen "
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Abundancia y riqueza específica de pulgones (Hemiptera: Aphididae) y sus parasitoides en diferentes genotipos y estados fenologicos del garbanzo Species richness and abundance of aphids (Hemiptera: Aphididae) and their parasitoids in different genotypes and at different growth stages of chickpea
V. E. Mazzuferi,A. Maidana,P. Fichetti,L. G. Hansen
Agriscientia , 2011,
Abstract: Los áfidos son insectos perjudiciales tanto por la succión de savia como por la transmisión de enfermedades. Los objetivos de este trabajo fueron conocer las especies de áfidos y sus parasitoides presentes en diferentes genotipos de garbanzo, calcular la incidencia del parasitismo e informar sobre las fluctuaciones poblacionales de pulgones y parasitoides en relación a los estados fenológicos del cultivo. El estudio se realizó durante 2006 y 2007 en San Marcos Sierras (Córdoba). Se evaluaron siete líneas y dos cultivares sembrados en un dise o en bloques completamente aleatorizados con tres repeticiones. Cada 15 días se colectaron manualmente áfidos y "momias" presentes en 10 plantas seleccionadas al azar, de cada genotipo y bloque. Se determinaron 13 especies de áfidos. En 2006 se observó mayor abundancia y riqueza de especies que en 2007. Las especies numéricamente dominantes fueron: Acyrthosiphon pisum y A. kondoi. Solamente cinco especies colonizaron el cultivo. El cultivar Cha aritos presentó la mayor abundancia de insectos en los dos a os agrícolas, y los genotipos M60 y M75 mostraron la mayor riqueza de especies. En ambos a os, los pulgones estuvieron presentes durante la etapa reproductiva del cultivo. Se registraron tres especies de parasitoides y se estimó un 35% de parasitismo total. Aphids may damage plants by sucking plant juices or by transmitting diseases. The aim of this study was to obtain further information about aphid species and their parasitoids in different genotypes of chickpea, calculate the incidence of parasitism and report on fluctuating populations (from aphids and parasitoid) in relation to plant phenology. The study was undertaken during 2006 and 2007 in San Marcos Sierras (Cordoba). Seven lines and two cultivars of chickpea were evaluated. Crop plots were planted following a completely randomized design block with 3 replicates. Every two weeks different developmental stages of aphids and "mummies" found in 10 plants randomly selected from each genotype and block were collected manually. Thirteen species of aphids were identified. In 2006 there was greater abundance and species richness than in 2007. The numerically dominant species were Acyrthosiphon pisum and A. kondoi. Only 5 species colonized the crop. Cha aritos presented the greatest abundance of insects in both years and M60 and M75 genotypes showed the greatest species richness. In both years, aphids were present during the reproductive stage. There were three species of parasitoids and parasitism was estimated at about 35%.
Thermodynamics and phase behavior of the lamellar Zwanzig model
L. Harnau,D. G. Rowan,J. -P. Hansen
Physics , 2002, DOI: 10.1063/1.1521936
Abstract: Binary mixtures of lamellar colloids represented by hard platelets are studied within a generalization of the Zwanzig model for rods, whereby the square cuboids can take only three orientations along the $x$, $y$ or $z$ axes. The free energy is calculated within Rosenfeld's ''Fundamental Measure Theory'' (FMT) adapted to the present model. In the one-component limit, the model exhibits the expected isotropic to nematic phase transition, which narrows as the aspect ratio $\zeta=L/D$ ($D$ is the width and $L$ the thickness of the platelets) increases. In the binary case the competition between nematic ordering and depletion-induced segregation leads to rich phase behaviour.
Faraday rotation and sensitivity of (100) bismuth-substituted ferrite garnet films
L. E. Helseth,A. G. Solovyev,R. W. Hansen
Physics , 2002, DOI: 10.1103/PhysRevB.66.064405
Abstract: We have investigated the Faraday rotation of in-plane magnetized bismuth - substituted ferrite garnet films grown by liquid phase epitaxy on (100) oriented gadolinium gallium garnet substrates. The Faraday spectra were measured for photon energies between 1.7 - 2.6 eV. To interprete the spectra, we use a model based on two electric dipole transitions, one tetrahedral and one octahedral. Furthermore, the Faraday rotation sensitivity was measured at 2.3 eV, and found to be in good agreement with the theoretical predicitions. In particular, we find that the sensitivity increases linearly with the bismuth content and nonlinearly with the gallium content.
DnaC Inactivation in Escherichia coli K-12 Induces the SOS Response and Expression of Nucleotide Biosynthesis Genes
Anders L?bner-Olesen, Monika Slominska-Wojewodzka, Flemming G. Hansen, Martin G. Marinus
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002984
Abstract: Background Initiation of chromosome replication in E. coli requires the DnaA and DnaC proteins and conditionally-lethal dnaA and dnaC mutants are often used to synchronize cell populations. Methodology/Principal Findings DNA microarrays were used to measure mRNA steady-state levels in initiation-deficient dnaA46 and dnaC2 bacteria at permissive and non-permissive temperatures and their expression profiles were compared to MG1655 wildtype cells. For both mutants there was altered expression of genes involved in nucleotide biosynthesis at the non-permissive temperature. Transcription of the dnaA and dnaC genes was increased at the non-permissive temperature in the respective mutant strains indicating auto-regulation of both genes. Induction of the SOS regulon was observed in dnaC2 cells at 38°C and 42°C. Flow cytometric analysis revealed that dnaC2 mutant cells at non-permissive temperature had completed the early stages of chromosome replication initiation. Conclusion/Significance We suggest that in dnaC2 cells the SOS response is triggered by persistent open-complex formation at oriC and/or by arrested forks that require DnaC for replication restart.
E-Learning and School Development - Strengths and Challenges of Capacity Building in School Development Projects
Line Skov Hansen,Anne-Karin Sunnev?g,Anne Kost?l
International Journal of Advanced Corporate Learning (iJAC) , 2011, DOI: 10.3991/ijac.v4i3.1737
Abstract: - This paper intends to focus on the strengths and challenges of capacity building in school development projects. The paper is based on practical experiences with three different projects CLL (Classroom Management, Learning and Teaching Authority) in Norway, the implementation of the LP- (learning environment and pedagogical analysis) model in Denmark as well as professional development of school administrators in a Danish municipality. The total number of participants in these projects is approximately 500 schools and 24 000 teachers and school administrators. One of the challenges about school improvement in general, is linked to the development of competences and training of employees. Training of teachers and school administrators is often costly in terms of time, finances and organization. In accordance with these challenges, Centre of the Study of Educational Practice (SePU), Norway and Centre for Knowledge-Based Educational Practice (CVIPP), Denmark have designed projects for developing competences and training based on “blended learning” concepts. The didactic designs, in all three projects, are based on problem-oriented e-learning modules that are approached in teams. Through learning in teams, competences are developed together with colleagues. Through e-learning training and development of competences can take place at each school, within the limits and resources available at the school by using e-learning. E-learning can therefore contribute to improved flexibility in human resource development and lifelong learning.
Noninvasive Vascular Displacement Estimation for Relative Elastic Modulus Reconstruction in Transversal Imaging Planes
Hendrik H. G. Hansen,Michael S. Richards,Marvin M. Doyley,Chris L. de Korte
Sensors , 2013, DOI: 10.3390/s130303341
Abstract: Atherosclerotic plaque rupture can initiate stroke or myocardial infarction. Lipid-rich plaques with thin fibrous caps have a higher risk to rupture than fibrotic plaques. Elastic moduli differ for lipid-rich and fibrous tissue and can be reconstructed using tissue displacements estimated from intravascular ultrasound radiofrequency (RF) data acquisitions. This study investigated if modulus reconstruction is possible for noninvasive RF acquisitions of vessels in transverse imaging planes using an iterative 2D cross-correlation based displacement estimation algorithm. Furthermore, since it is known that displacements can be improved by compounding of displacements estimated at various beam steering angles, we compared the performance of the modulus reconstruction with and without compounding. For the comparison, simulated and experimental RF data were generated of various vessel-mimicking phantoms. Reconstruction errors were less than 10%, which seems adequate for distinguishing lipid-rich from fibrous tissue. Compounding outperformed single-angle reconstruction: the interquartile range of the reconstructed moduli for the various homogeneous phantom layers was approximately two times smaller. Additionally, the estimated lateral displacements were a factor of 2–3 better matched to the displacements corresponding to the reconstructed modulus distribution. Thus, noninvasive elastic modulus reconstruction is possible for transverse vessel cross sections using this cross-correlation method and is more accurate with compounding.
Population-Based Resequencing of APOA1 in 10,330 Individuals: Spectrum of Genetic Variation, Phenotype, and Comparison with Extreme Phenotype Approach
Christiane L. Haase,Ruth Frikke-Schmidt,B?rge G. Nordestgaard,Anne Tybj?rg-Hansen
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1003063
Abstract: Rare genetic variants, identified by in-detail resequencing of loci, may contribute to complex traits. We used the apolipoprotein A-I gene (APOA1), a major high-density lipoprotein (HDL) gene, and population-based resequencing to determine the spectrum of genetic variants, the phenotypic characteristics of these variants, and how these results compared with results based on resequencing only the extremes of the apolipoprotein A-I (apoA-I) distribution. First, we resequenced APOA1 in 10,330 population-based participants in the Copenhagen City Heart Study. The spectrum and distribution of genetic variants was determined as a function of the number of individuals resequenced. Second, apoA-I and HDL cholesterol phenotypes were determined for nonsynonymous (NS) and synonymous (S) variants and were validated in the Copenhagen General Population Study (n = 45,239). Third, observed phenotypes were compared with those predicted using an extreme phenotype approach based on the apoA-I distribution. Our results are as follows: First, population-based resequencing of APOA1 identified 40 variants of which only 7 (18%) had minor allele frequencies >1%, and most were exceedingly rare. Second, 0.27% of individuals in the general population were heterozygous for NS variants which were associated with substantial reductions in apoA-I (up to 39 mg/dL) and/or HDL cholesterol (up to 0.9 mmol/L) and, surprisingly, 0.41% were heterozygous for variants predisposing to amyloidosis. NS variants associated with a hazard ratio of 1.72 (1.09–2.70) for myocardial infarction (MI), largely driven by A164S, a variant not associated with apoA-I or HDL cholesterol levels. Third, using the extreme apoA-I phenotype approach, NS variants correctly predicted the apoA-I phenotype observed in the population-based resequencing. However, using the extreme approach, between 79% (screening 0–1st percentile) and 21% (screening 0–20th percentile) of all variants were not identified; among these were variants previously associated with amyloidosis. Population-based resequencing of APOA1 identified a majority of rare NS variants associated with reduced apoA-1 and HDL cholesterol levels and/or predisposing to amyloidosis. In addition, NS variants associated with increased risk of MI.
Symptomatic Primary (AL) Amyloidosis of the Stomach and Duodenum
Reidar Fossmark,Espen Skarsv?g,Harald Aarset,Henrik Hjorth-Hansen,Helge L. Waldum
Case Reports in Gastrointestinal Medicine , 2013, DOI: 10.1155/2013/525439
Abstract: Primary (AL) amyloidosis of the gastrointestinal tract is relatively rare, and symptomatic amyloidosis of the stomach is even more seldom. We present the case of a patient who was referred to upper endoscopy because of weight loss, nausea, and vomiting. Large areas of intramucosal hemorrhages were seen, and biopsies resulted in profuse bleeding stopped with endoscopic clips. The biopsies showed amyloid depositions and further workup revealed that the patient also had cardiac and neuropathic involvements. The patient started treatment with dexamethasone, melphalan and bortezomib. After treatment was started the nausea and epigastric discomfort improved, and a reduction in the biochemical markers troponin T, NT-proBNP, and M-component was observed. Gastric amyloidosis is rarely seen at upper endoscopy in patients without a previously established diagnosis, but the unusual endoscopic findings and bleeding tendency after biopsy should be kept in mind by gastroenterologists. 1. Introduction Gastrointestinal involvement in amyloidosis is seen in primary (AL) amyloidosis, secondary (AA) amyloidosis, and dialysis-related (β2-microglobulin) amyloidosis. Primary (AL) amyloidosis of the gastrointestinal tract is relatively rare, and only 8% of patients were reported to have amyloidosis in biopsies from the GI tract, whereas only 1% had symptomatic amyloidosis of the stomach in a series of 769 patients [1]. Amyloidosis involving the gastrointestinal tract may cause symptoms related to altered motility, gastrointestinal bleeding, or malabsorption. In the stomach, gastric amyloidosis may have an endoscopic appearance mimicking gastric neoplasia [2, 3], hematomas, erosions and ulcerations, or a nodular gastritis [4]. The diagnosis of gastrointestinal amyloidosis may be hard to suspect in patients without previously diagnosed inflammatory or plasma cell disease. 2. Case A 74-year-old woman was referred to upper gastrointestinal endoscopy due to weight loss of 10?kg in 6 months, epigastric discomfort, nausea, and episodes of vomiting. She had a previous history of a tachy-brady syndrome resulting in pacemaker implantation two years before and received metoprolol treatment. Upper endoscopy showed large areas of intramucosal hemorrhage, mainly in the corpus and cardia of the stomach, whereas in the duodenal bulb, there was a polypoid lesion (Figure 1). A biopsy was taken from a small area with modest signs of intramucosal hemorrhage resulted in a profuse bleeding that was stopped with endoscopic clips. Biopsy collection from the polypoid lesion in the duodenum was
Conditional quantum state engineering in repeated 2-photon down conversion
J. Clausen,H. Hansen,L. Knoll,J. Mlynek,D. -G. Welsch
Physics , 2000, DOI: 10.1007/s003400000480
Abstract: The U(1,1) and U(2) transformations realized by three-mode interaction in the respective parametric approximations are studied in conditional measurement, and the corresponding non-unitary transformation operators are derived. As an application, the preparation of single-mode quantum states using an optical feedback loop is discussed, with special emphasis of Fock state preparation. For that example, the influence of non-perfect detection and feedback is also considered.
Construct-Validity of the Engagement with Challenge Measure for Adolescents: Structural- and Criterion-Validity Evidence  [PDF]
E. Whitney G. Moore, David Hansen
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.310139
Abstract: or adolescents, engaging with challenge is a key developmental task, hypothesized to support development of adult-like competencies (e.g., agency and self-direction; Larson, 2000). This study aimed to assess the construct-validity (structural- and concurrent-validity) of a new self-report measure assessing adolescents’ engagement with challenge to help researchers understand how different settings and the conditions in these settings support adolescents’ development. The sample consisted of 337 adolescents in 10 FFA programs along with the adult advisors in each program. Adolescents completed a questionnaire, which included the Engagement with Challenge measure and the following criterion variables: number of contests completed, participation frequency, and leadership roles. In addition to the self-reported criterion variables, the adult advisor evaluated Engagement with Challenge for each FFA student member in that program using a single item. The findings of this study provided strong evidence for the structural-validity of the engagement with challenge construct measured by the new scale, including having passed confirmatory factor analysis configural, weak, and strong invariance tests across four grade groupings. The findings also provided further evidence of construct-validity, as Engagement with Challenge correlated in the a priori hypothesized direction and magnitude. Suggestions for analysis with the new measure and for future research are presented.
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