2,413 research outputs found
An Electro - Optical Test System for Optimising Operating Conditions of CCD sensors for LSST
We describe the commissioning of a system which has been built to investigate
optimal operation of CCDs for the LSST telescope. The test system is designed
for low vibration, high stability operation and is capable of illuminating a
detector in flat-field, projected spot, projected pattern and Fe-55
configurations. We compare and describe some considerations when choosing a
gain calibration method for CCDs which exhibit the brighter-fatter effect. An
optimisation study on a prototype device of gain and full well with varying
back substrate bias and gate clock levels is presented
Modelling seasonality in South African agricultural futures
Includes bibliographical references (leaves 86-87).This study investigates the seasonality in agricultural commodity futures prices. Futures prices are modelled using the model developed by Sørensen (2002). The model defines the commodity spot price as the sum of a nonstationary state variable, a stationary state variable and a deterministic seasonal component. Standard no-arbitrage arguments are applied in order to derive futures and option prices. Model parameters are estimated using Kalman filter methodology and maximum likelihood estimation. Model parameters are estimated for white maize, yellow maize and wheat futures traded on the South African Futures Exchange (SAFEX). Furthermore, this research considers other models for commodity derivatives as well as pricing futures contracts in the presence of price limits
Bicultural self-efficacy, student achievement, and persistence of Mexican American college students
This mixed methods study will explore the relationship of bi-cultural self-efficacy with student achievement and persistence for first generation Mexican American students enrolled at a two year college. The Bicultural Self Efficacy Scale for Minority Adults (BISES-MA ) will be used to collect quantitative data from a study group and control group. The study group will participate in a student success course using high engagement strategies developed by Advancement Via Individual Determination for Higher Education (AHE). Analysis of variance will be conducted to determine the degree of difference between the study and control groups on bicultural self-efficacy and student achievement and persistence. Qualitative data will be collected through focus group interviews of study group participants. Employing a grounded theory approach, responses will be analyzed to surface themes that explain the relationship of bicultural self-efficacy with academic achievement and persistence as measured by the BISES-MA survey
BIMA N2H+ 1-0 mapping observations of L183 -- fragmentation and spin-up in a collapsing, magnetized, rotating, pre-stellar core
We have used the Berkeley-Illinois-Maryland Array (BIMA) to make deep N2H+
1-0 maps of the pre-stellar core L183, in order to study the spatial and
kinematic substructure within the densest part of the core. Three spatially and
kinematically distinct clumps are detected, which we label L183-N1, L183-N2 and
L183-N3. L183-N2 is approximately coincident with the submillimetre dust peak
and lies at the systemic velocity of L183. Thus we conclude that L183-N2 is the
central dense core of L183. L183-N1 and 3 are newly-discovered fragments of
L183, which are marked by velocity gradients that are parallel to, but far
stronger than, the velocity gradient of L183 as a whole, as detected in
previous single-dish data. Furthermore, the ratio of the large-scale and
small-scale velocity gradients, and the ratio of their respective size-scales,
are consistent with the conservation of angular momentum for a rotating,
collapsing core undergoing spin-up. The inferred axis of rotation is parallel
to the magnetic field direction, which is offset from its long axis, as we have
seen in other pre-stellar cores. Therefore, we propose that we have detected a
fragmenting, collapsing, filamentary, pre-stellar core, rotating about its
B-field, which is spinning up as it collapses. It will presumably go on to form
a multiple protostellar system.Comment: 7 figures, 1 table, 21 pages, accepted for publication in Ap
Modernization in the Virginia General Assembly : the Commission on the Legislative Process 1972-73
Of the forces which led to institutional modernization in the Virginia General Assembly in the early 1970\u27s, the Commission on the Legislative Process was one of the most significant. The Commission focused its attention on those administrative, managerial and structural problems which were among the most significant impedi ments to the Assembly\u27s efficient operation. In the administrative and managerial areas the Commission had great success. Administrative improvements in staff support were especially significant. Staff support was recommended and subsequently approved for individual legislators, standing committees and the Assembly as a whole
Modeling the effects of landscape structure on the spatial distribution of brown-headed cowbirds and nest parasitism in forest openings
Apparent declines of breeding neotropical migrant land bird populations in the United States over the last 25 years have been associated with increases in populations of brown-headed cowbirds (Molothrus ater). Because cowbirds parasitize nests of many of these species, such parasitism may be a major contributing factor to these declines. I used avian-census data and landscape-level habitat variables to develop models predicting the presence/absence of cowbirds and nest parasitism in forest openings in a predominately forested (89%) landscape at Land Between the Lakes in Kentucky and western Tennessee.
Cowbird populations were surveyed in forest-opening and interior-forest settings between 15 May and 1 July 1993 and 1994, using 10-minute, 50-m fixed-radius point counts. Cowbirds were present within 50 m in 62 (27%) of 227 forest-opening and interior forest points. Cowbirds were present at forest-opening edges more often than at interior forest points (P ≤ 0.05). Cowbird presence did not differ by distance from edge for interior-forest points (200, 300, 400, and 500-m points) (P \u3e 0.05). Overall cowbird abundance per point (forest-opening and interior-forest points) was 0.53 cowbirds/point. Cowbirds were more abundant at forest-opening edges than at interior forest points (P ≤ 0.05). Cowbird abundance did not differ by distance from edge for interior-forest points (P \u3e 0.05).
Potential cowbird host nests were located and monitored between 15 May and 1 July 1994. A total of 195 active nests of 20 species known to be parasitized by brown-headed cowbirds were located and monitored. Of these nests, 23.6% (46 nests) were parasitized by cowbirds. The percentage of nests parasitized did not differ across distance from nest to nearest edge categories (P \u3e 0.05). Forest species were more heavily parasitized (30.5% of 82 nests) than were edge species (18.6% of 113 nests parasitized) (P = 0.03).
A logistic regression model was developed to predict cowbird presence/absence in forest openings based on 17 landscape and avian census variables associated with each opening. Forest opening size (ha), average height of vegetation in the opening (m), and the number of potential cowbird foraging locations within a 2-km radius of the opening were the best predictors of cowbird presence/absence in forest openings. Larger forest openings, with lower average vegetation heights that were near a high concentration of foraging locations were the most likely to have cowbirds present. Using these model variables, predicted and observed responses were concordant 90.0% of the time, and forest openings were correctly classified for cowbird presence/absence 82.9% of the time.
A logistic regression model was developed to predict the presence/absence of nest parasitism in forest openings based on 20 landscape and avian census variables associated with each opening. Forest opening size (ha), average height of vegetation in the opening, and the number of potential cowbird foraging locations within 2 km of the opening were the best predictors of the presence of nest parasitism presence/absence in forest openings. Smaller forest openings, with higher average vegetation heights that were near a high concentration of foraging locations were most likely to have nest parasitism present. Using these model variables, predicted and observed responses were concordant 85.2% of the time and forest openings were correctly classified for nest parasitism presence/absence 81.8% of the time.
A total of 148 point counts and recorded playback sessions of cowbird vocalizations were conducted in forest-opening and interior-forest settings between 15 May and 1 July 1993. 1 assessed the effects of point-count duration cowbird .detection and estimates of cowbird abundance. I also compared the efficiency of point-count versus recorded-playback techniques for detecting cowbirds and estimating cowbird abundance. Ten-minute point counts were suggested to be the best option for managers initiating efforts to monitor cowbird populations. Point count and playback techniques yielded similar results (P \u3e 0.05) for detecting cowbird presence and estimating cowbird abundance
The anger 01- jesus in mark's gospel
The textual variants in Markan passages depicting the anger of Jesus coupled with Matthaean and Lukan amendments to and omissions from them, suggest that discomfort at the thought of Jesus' anger is no merely modern phenomenon. Nevertheless its possibility still strikes some as bizarre and some as impossible. However, in this thesis I argue that, far from being extraneous or peripheral. Jesus' anger is integral to Mark's presentation of the gospel First, it illustrates Mark's claim that Jesus was the son of God. Many of the themes associated with God's anger in the Old Testament are discernible also in Mark's Gospel. Furthermore, in Mark Jesus alone expresses 6prn . and, while the indignations of others are invariably condemned, Jesus' expressions of anger are always cast in a positive and even divine light. Secondly the anger of Jesus highlights the importance of the various issues which were the subject of intense debate between Christians and Jews, within Judaism itself and among his own followers. The status of the law, the nature and purpose of miracles, the meaning of suffering, the roles of children, outsiders and Gentiles are all very much to the fore in the Markan pericopae which depict Jesus' anger. His anger proclaims their seriousness and the urgency with which they should be tackled The notion of Jesus' anger involves, inevitably, some recognition of the mystery surrounding his character and his relationship with God However, one of Mark's main points seems to be that Jesus is an enigma only to the hard of heart and the blind in perception. In the six Markan passages, which are the subject of this thesis, Jesus lays down clear principles for faith, action and discipline. His anger underlines their importance and his own authority
From leaders to leadership
Pre-print; author's draft; Final version published as From `Leaders' to `Leadership' : nurturing a leadership cultureThis article presents a view of institutional leadership that is a relational process of organisational member (and other key stakeholders), irrespective of position or status, taking up their role in the purposes of the enterprise
African leadership: surfacing new understandings through leadership development
Draft version issued as working paper. Final published version available online at http://online.sagepub.com/This article provides an account of meanings and connotations of ‘African leadership’ emerging from research with a cohort of participants on a Pan-African leadership development programme. We begin by reviewing current approaches to leadership, and how they have been applied to the study of leadership and management across cultures, before introducing the notion of the ‘African renaissance’, which calls for a re-engagement with indigenous knowledge and practices. The findings from our study indicate a tension between accounts and representations of leadership and the potential for leadership development to act as a forum in which participants can work through these issues. In developing an Afro-centric perspective on leadership, we propose that development activities that promote relational, critical and constructionist perspectives on leadership, with an emphasis on dialogue and sharing experience, could be an important means for surfacing new insights and understandings. In particular, they offer a mechanism by which participants can enhance their sense of ‘self in community’, generate shared understandings, challenge repressive power relations, and develop culturally appropriate forms of leadership behaviour. We conclude by proposing that further research is required on leadership in Africa that steps outside dominant methodological and empirical paradigms, and argue that such work holds great potential for generating insights not just relevant to leadership in Africa but to leadership studies in general
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