14,406 research outputs found

    Columnar defects acting as passive internal field detectors

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    We have studied the angular dependence of the irreversible magnetization of several YBa2_2Cu3_3O7_7 and 2H-NbSe2_2 single crystals with columnar defects tilted off the c-axis. At high magnetic fields, the irreversible magnetization Mi(ΘH)M_i(\Theta_H) exhibits a well known maximum when the applied field is parallel to the tracks. As the field is decreased below H∼0.02Hc2H \sim 0.02 H_{c2}, the peak shifts away from the tracks' direction toward either the c-axis or the ab-planes. We demonstrate that this shift results from the misalignment between the external and internal field directions due to the competition between anisotropy and geometry effects.Comment: 5 figure

    Drastic annealing effects in transport properties of single crystals of the YbNi2B2C heavy fermion system

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    We report temperature dependent resistivity, specific heat, magnetic susceptibility and thermoelectric power measurements made on the heavy fermion system YbNi2B2C, for both as grown and annealed single crystals. Our results demonstrate a significant variation in the temperature dependent electrical resistivity and thermoelectric power between as grown crystals and crystals that have undergone optimal (150 hour, 950 C) annealing, whereas the thermodynamic properties: (c_p(T) and chi(T)) remain almost unchanged. We interpret these results in terms of redistributions of local Kondo temperatures associated with ligandal disorder for a small (~ 1%) fraction of the Yb sites.Comment: 5 pages, 4 figures, submitted to PR

    Optical Turbulence Measurements and Models for Mount John University Observatory

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    Site measurements were collected at Mount John University Observatory in 2005 and 2007 using a purpose-built scintillation detection and ranging system. Cn2(h)C_n^2(h) profiling indicates a weak layer located at 12 - 14 km above sea level and strong low altitude turbulence extending up to 5 km. During calm weather conditions, an additional layer was detected at 6 - 8 km above sea level. V(h)V(h) profiling suggests that tropopause layer velocities are nominally 12 - 30 m/s, and near-ground velocities range between 2 -- 20 m/s, dependent on weather. Little seasonal variation was detected in either Cn2(h)C_n^2(h) and V(h)V(h) profiles. The average coherence length, r0r_0, was found to be 7±17 \pm 1 cm for the full profile at a wavelength of 589 nm. The average isoplanatic angle, θ0\theta_0, was 1.0±0.11.0 \pm 0.1 arcsec. The mean turbulence altitude, h0ˉ\bar{h_0}, was found to be 2.0±0.72.0\pm0.7 km above sea level. No average in the Greenwood frequency, fGf_G, could be established due to the gaps present in the \vw\s profiles obtained. A modified Hufnagel-Valley model was developed to describe the Cn2(h)C_n^2(h) profiles at Mount John, which estimates r0r_0 at 6 cm and θ0\theta_0 at 0.9 arcsec. A series of V(h)V(h) models were developed, based on the Greenwood wind model with an additional peak located at low altitudes. Using the Cn2(h)C_n^2(h) model and the suggested V(h)V(h) model for moderate ground wind speeds, fGf_G is estimated at 79 Hz.Comment: 14 pages; accepted for publication in PAS

    Development of fad7-1 single mutant Arabidopsis thaliana plants that are resistant to aphids

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    Aphids are a group of sap-feeding insects that attack most of the world’s crops. The loss of function of fatty acid desaturase7 (FAD7) in Solanum lycopersicum (tomato plant) induces aphid resistance that is dependent upon the accumulation of plant defense hormones such as salicylic acid (SA). Tomato lacks most of the genetic resources found in the model plant Arabidopsis (Arabidopsis thaliana). There is an analogous fad7-1 line of Arabidopsis; however, the line has a background mutation, the glabra-1 (gl1), that causes the absence of trichomes (small hairs), which are essential to plant defense. In order to study aphid resistance, a single mutant line of fad7-1 mutants were developed using cross breeding between the fad7-1/gl1 mutant and wild-type plants. Homozygous fad7-1 mutants were then identified using the Kasajima DNA extraction method, followed by the use of single nucleotide polymorphism-polymerase chain reaction (SNP-PCR) primers using allele-specific PCR. A phenotypic screening was then performed to screen out the plants with the glabra-1 mutation using the presence or absence of trichomes. Two single Arabidopsis fad7-1 mutant lines were identified, and subsequently verified using a bioassay to be aphid resistant relative to other genotypes as seen in tomato

    Total Quality Management (TQM) Practices of School Administrators in Relation to School Performance among Teacher Education Institutions in the Province of Quezon

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    One of the emerging philosophies of management is that of total quality management. Total quality management has received wide acclaim enhancement in industry as well as school nowadays. School started to explore the potential for applying the TQM philosophy to education, this requires the number of changes in any educational institution particularly in the attitudes and activities of the leadership and educators, in the organization, monitoring of educational process, in the evaluation of the result, in the culture of communication, in the school atmosphere and especially in the area of interpersonal relations. The School administrators being the highest-ranking official in the school are responsible for the overall operation of a school, and in the 21st century the school administrator wear a multiple of hats just to make sure that the operation in the school goes smoothly, meaning the effectiveness with which he/she handle the tasks assigned to him being the growing interest in improving the efficiency and relevance of these activities is reflected in the adaption of total quality management mechanism, through the institutional actions towards the development of a quality culture, these embedding the philosophy of centennial improvement or the processes of institutional modernization, search for critical factors and clarification of mission and objectives which will eventually lead to quality improvement. The study assessed the total quality management practices of school administrators in terms of curriculum and instruction, human resources, physical facilities, budget allocation and research in selected teacher educational institutions in the Province of Quezon in relation to school performance for the first semester of SY: 2016-2017. The respondents included 132 teachers and 37 school administrators for eight Teacher Education Program in the Province of Quezon both private and public colleges/universities. Included in the assessment are the status of the school performance in terms of faculty performance, enrollment rate, dropped-out rate, retention rate and graduation rate and the awards and recognitions received by the respondent schools. The research on the Total Quality Management Practices hoped to bring improvement in the quality of education for the respondent schools and could also provide information on how this could be done by school administrators in the operation of the school, the students on the other hand maybe guided by the skills of the school administrators that may affect their academic performance. The study was anchored with Deming’s theory of Total Quality management, where it was believed to provide quality body of methodologies that are customer-based and service oriented. As mentioned the study assessed the total quality management practices of school administrators in selected teacher educational institutions in the Province of Quezon in relation to school’s performance and eventually to find out if there is a significant relationship between the assessment of TQM practices of the school administrators and performance of the school and at the end developed an action plan just to enhance the TQM practices to improve the school performance. The study used the descriptive research for this is the precise research design applicable to be used, this study described the total quality management practices of school administrators in selected teacher educational institutions in the Province of Quezon in relation to the students’ academic Performance. As told by Calderon, descriptive research is the process of gathering, analyzing, classifying and tabulating data about prevailing conditions, practices, beliefs, processes, trends and cause-effect relationshipand eventually making adequate interpretation of such data. This process fits the Kind of research undertaken by this study. The purposive sampling technique was used for the selection of the respondents (teachers and school administrators). The researcher prepared a questionnaires which was used in gathering data and this was validated by experts in the field of educational leadership and with enough experiences in leadership and management practices of the different educational programs in the tertiary level. The researcher personally disseminated the questionnaire to the respondents, and after answering personally retrieved then, an unstructured interview was also conducted both to the school administrators and teacher respondents to elicit some information and answers which were not clearly expounded from the questionnaire. These data obtained were collected, tabulated, analyzed and interpreted using some stalestical tools. Keywords: School Administrators, Performance, Strategic Directio

    Effects Associated with Dredging for Beach Renourishments on Reef Fish Communities Offshore of Miami-Dade County, Florida:

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    Beach erosion is an ongoing problem in South Florida. Beach replenishment has been the primary means of maintaining these economically important beaches, and dredging offshore sand deposits, adjacent to reef tracts, has been the pervasive method since the 1970\u27s. Over the past ten years, greater attention has been paid to potential impacts dredging can have on adjacent reef communities, which has led to increased monitoring efforts. With the increase in monitoring efforts, scope has expanded from a strict focus on the benthic community to include the fish communities. This study evaluates the effects of dredging on reef fish communities associated with two separate beach replenishment projects, offshore of Miami-Dade County, Florida, U.S.A. Monitoring programs were developed and conducted by the Miami-Dade, Department of Environmental Resources Management (DERM). Monitoring took place between March 1997 and September 2000, with one project in northern portion of the county, off offshore of Golden Beach, and the other in the southern portion offshore of Key Biscayne. Both monitoring programs employed a Before After Control Impact design, with established test and control reef stations. Eight reef fish visual point count censuses (Bohnsack and Bannerot, 1986) were performed at each station prior to dredging, immediately following dredging, and three periods at bi-quarterly intervals after that. In general evaluations of both project,s showed no indications that dredging activities had major impacts on the fish communities of adjacent reefs. For the Golden Beach project, there was one aspect of the analysis, which may be indicative of dredging related impacts; was species richness at one test station declined significantly following dredging activities (ANOVA p=0.047). However, in terms of abundance, diversity and Multidimensional scaling (MDS) plots of the Bray-Curtis dissimilarity index did not indicate that dredging activities impacted the test station. During the monitoring period of the Key Biscayne project, the south Florida region was impacted by two tropical storm events, which obscures the isolation of impacts associated with dredging. Changes in the reef fish communities, consistent with the impact and recovery of the tropical storms are evident in species richness, abundance, and MDS plots of the Bray-Curtis dissimilarity index, at both the test and control stations

    Conceptual Model for Serious Games Design: Case Study of Children with Attention Deficit Hyperactivity Disorder

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    The field of Serious Games (SGs) is relatively new; however, so far, these have focused more on assessing impacts on results rather than identifying the most appropriate implementation phases to obtain a successful SG. The present work proposes a conceptual model for the design of SGs, which is based on four stages: Analysis, Design, Development, and Evaluation, under the life cycle of the software. For the validation of the model, an SG called ATHYNOS was developed, which was applied in a case study comparing it with the traditional therapy. The results obtained allowed to demonstrate that the SGs is a complementary tool for the treatment of children diagnosed with Attention Deficit Hyperactivity Disorder (ADHD).     Keywords: ATHYNOS, conceptual model, serious games design, attention deficit disorde
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