1,036 research outputs found
The effect of competition and date of planting on the growth of soybean varieties having different dates of maturity
This experiment was intended to study competition effects between unlike varieties, and to determine the need for three-row plots to eliminate any bias that may exist as a result of competition
Biogenesis of the inner membrane complex is dependent on vesicular transport by the alveolate specific GTPase Rab11B
Apicomplexan parasites belong to a recently recognised group of protozoa referred to as Alveolata. These protists contain membranous sacs (alveoli) beneath the plasma membrane, termed the Inner Membrane Complex (IMC) in the case of Apicomplexa. During parasite replication the IMC is formed de novo within the mother cell in a process described as internal budding. We hypothesized that an alveolate specific factor is involved in the specific transport of vesicles from the Golgi to the IMC and identified the small GTPase Rab11B as an alveolate specific Rab-GTPase that localises to the growing end of the IMC during replication of Toxoplasma gondii. Conditional interference with Rab11B function leads to a profound defect in IMC biogenesis, indicating that Rab11B is required for the transport of Golgi derived vesicles to the nascent IMC of the daughter cell. Curiously, a block in IMC biogenesis did not affect formation of sub-pellicular microtubules, indicating that IMC biogenesis and formation of sub-pellicular microtubules is not mechanistically linked. We propose a model where Rab11B specifically transports vesicles derived from the Golgi to the immature IMC of the growing daughter parasites
The impact of the demographic transition on dengue in Thailand: Insights from a statistical analysis and mathematical modeling
Background: An increase in the average age of dengue hemorrhagic fever (DHF) cases has been reported in Thailand. The cause of this increase is not known. Possible explanations include a reduction in transmission due to declining mosquito populations, declining contact between human and mosquito, and changes in reporting. We propose that a demographic shift toward lower birth and death rates has reduced dengue transmission and lengthened the interval between large epidemics. Methods and Findings: Using data from each of the 72 provinces of Thailand, we looked for associations between force of infection (a measure of hazard, defined as the rate per capita at which susceptible individuals become infected) and demographic and climactic variables. We estimated the force of infection from the age distribution of cases from 1985 to 2005. We find that the force of infection has declined by 2% each year since a peak in the late 1970s and early 1980s. Contrary to recent findings suggesting that the incidence of DHF has increased in Thailand, we find a small but statistically significant decline in DHF incidence since 1985 in a majority of provinces. The strongest predictor of the change in force of infection and the mean force of infection is the median age of the population. Using mathematical simulations of dengue transmission we show that a reduced birth rate and a shift in the population's age structure can explain the shift in the age distribution of cases, reduction of the force of infection, and increase in the periodicity of multiannual oscillations of DHF incidence in the absence of other changes. Conclusions: Lower birth and death rates decrease the flow of susceptible individuals into the population and increase the longevity of immune individuals. The increase in the proportion of the population that is immune increases the likelihood that an infectious mosquito will feed on an immune individual, reducing the force of infection. Though the force of infection has decreased by half, we find that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon
The role of clathrin in post-golgi trafficking in toxoplasma gondii
Apicomplexan parasites are single eukaryotic cells with a highly polarised secretory system that contains unique secretory organelles (micronemes and rhoptries) that are required for host cell invasion. In contrast, the role of the endosomal system is poorly understood in these parasites. With many typical endocytic factors missing, we speculated that endocytosis depends exclusively on a clathrin-mediated mechanism. Intriguingly, in Toxoplasma gondii we were only able to observe the endogenous clathrin heavy chain 1 (CHC1) at the Golgi, but not at the parasite surface. For the functional characterisation of Toxoplasma gondii CHC1 we generated parasite mutants conditionally expressing the dominant negative clathrin Hub fragment and demonstrate that CHC1 is essential for vesicle formation at the trans-Golgi network. Consequently, the functional ablation of CHC1 results in Golgi aberrations, a block in the biogenesis of the unique secretory microneme and rhoptry organelles, and of the pellicle. However, we found no morphological evidence for clathrin mediating endocytosis in these parasites and speculate that they remodelled their vesicular trafficking system to adapt to an intracellular lifestyle
Do Damped and Sub-damped Lyman-alpha Absorbers Arise in Galaxies of Different Masses?
We consider the questions of whether the damped Lyman-alpha (DLA) and sub-DLA
absorbers in quasar spectra differ intrinsically in metallicity, and whether
they could arise in galaxies of different masses. Using the recent measurements
of the robust metallicity indicators Zn and S in DLAs and sub-DLAs, we confirm
that sub-DLAs have higher mean metallicities than DLAs, especially at . We find that the intercept of the metallicity-redshift relation
derived from Zn and S is higher than that derived from Fe by 0.5-0.6 dex. We
also show that, while there is a correlation between the metallicity and the
rest equivalent width of Mg II or Fe II for DLAs,
no correlation is seen for sub-DLAs. Given this, and the similar Mg II or Fe II
selection criteria employed in the discovery of both types of systems at lower
redshifts, the difference between metallicities of DLAs and sub-DLAs appears to
be real and not an artefact of selection. This conclusion is supported by our
simulations of Mg II and Fe II lines for a wide
range of physical conditions. On examining the velocity spreads of the
absorbers, we find that sub-DLAs show somewhat higher mean and median velocity
spreads (), and an excess of systems with km
s, than DLAs. Compared to DLAs, the [Mn/Fe] vs. [Zn/H] trend for
sub-DLAs appears to be steeper and closer to the trend for Galactic bulge and
thick disk stars, possibly suggesting different stellar populations. The
absorber data appear to be consistent with galaxy down-sizing. The data are
also consistent with the relative number densities of low-mass and high-mass
galaxies. It is thus plausible that sub-DLAs arise in more massive galaxies on
average than DLAs.Comment: 27 pages, 5 figures, 4 tables. Accepted for publication in New
Astronom
Hubble Space Telescope Imaging of Lyman Alpha Emission at z=4.4
We present the highest redshift detections of resolved Lyman alpha emission,
using Hubble Space Telescope/ACS F658N narrowband-imaging data taken in
parallel with the Wide Field Camera 3 Early Release Science program in the
GOODS CDF-S. We detect Lyman alpha emission from three spectroscopically
confirmed z = 4.4 Lyman alpha emitting galaxies (LAEs), more than doubling the
sample of LAEs with resolved Lyman alpha emission. Comparing the light
distribution between the rest-frame ultraviolet continuum and narrowband
images, we investigate the escape of Lyman alpha photons at high redshift.
While our data do not support a positional offset between the Lyman alpha and
rest-frame ultraviolet (UV) continuum emission, the half-light radii in two out
of the three galaxies are significantly larger in Lyman alpha than in the
rest-frame UV continuum. This result is confirmed when comparing object sizes
in a stack of all objects in both bands. Additionally, the narrowband flux
detected with HST is significantly less than observed in similar filters from
the ground. These results together imply that the Lyman alpha emission is not
strictly confined to its indigenous star-forming regions. Rather, the Lyman
alpha emission is more extended, with the missing HST flux likely existing in a
diffuse outer halo. This suggests that the radiative transfer of Lyman alpha
photons in high-redshift LAEs is complicated, with the interstellar-medium
geometry and/or outflows playing a significant role in galaxies at these
redshifts.Comment: Submitted to the Astrophysical Journal. 11 pages, 10 figure
Mineral chemistry of igneous melanite garnets from analcite-bearing volcanic rocks, Alberta, Canada
The mineral chemistry of melanite garnets from the Crowsnest volcanic rocks of SW Alberta, Canada, has been investigated by using electron microprobe scans, quantitative analyses and multivariate statistical analysis. The garnets occur with aegirine-augite, sanidine, analcite and rare plagioclase as phenocrysts in trachyte and phonolite flows, agglomerates and tuffs. Wavelength dispersive microprobe scans reveal complex zonation patterns, both normal and oscillatory. The results of fifty quantitative analyses were subjected to R-mode factor analysis to delineate the chemical exchanges producing the zonation. The chemical zonation of the garnets may be attributed to four independent binary exchanges; Al-Fe3+, Si-Ti, Ca-Mn and Mg-Fe2+. The stoichiometry of these garnets, based on microprobe and wet chemical Fe analyses, combined with the strongly antithetic behavior of Si and Ti lead us to infer that the Ti in these garnets is dominantly tetravalent. It is clear from this study that quantitative modelling of the processes of crystal growth and zonation of melanite garnets in alkaline, undersaturated igneous rocks should be aimed at simulating the four chemical exchanges listed above
1960: Abilene Christian College Lectures - Full Text
Table of Contents:
Theme Speeches: Christian Faith in the Modern World
Basis of Faith - Leonard Mullens - 9
Authority in Christianity - John T. Smithson, Jr. - 27
Origin and Preservation of the Bible - Neil R. Lightfoot - 44
Alleged Discrepancies of the Bible - David H. Bobo - 62
The Unity of the Bible - Jack Meyer - 91
Faith and Reason - Joe Sanders - 115
The Reasonableness of Supernaturalism - Virgil Trout - 126
The Present Statue of the Doctrine of Organic Evolution - J.D. Thomas - 146
The Nature of Man - Roy F. Osborne, Jr. - 181
Modern Challenges to Christian Morals - Carl Spain - 199
The Christ, Whose Son is He? - Gordon Teel - 232
Special Speeches
Teaching the Word of God in Korea - L. Haskell Chessfire - 255
The Influence of Christian Education - Judge Jack Pope - 276
Mission Opportunities in the Far East - Harry Robert Fox - 288
Mission Work in Austria - Robert Skelton - 303
Report from Switzerland - Heinrich Blum - 313
The Work in Nigeria - Rees Byrant - 320
The Training of Evangelists in Foreign Fields - Reiner Kallus - 331
Christian Scholarships - Everett Ferguson - 340
Evangelizing the World - A.R. Holton - 349
Panel Discussions
The Significance of the Dead Sea Scrolls
The Scrolls and the Text of the Bible - Paul Rotenberry - 357
The Relation between the Religion of the Essenes and that of Early Christians - Jay Smith - 366
Biblical Interpretation
Expediency and Pattern Authority - J.W. Roberts - 381
Examples in Pattern Authority - Thomas B. Warren - 392
Mental Health and Sin
The Present State of Mental Health Knowledge - Donald R. Sime - 409
The Relationship of Mental Health Problems to Sin - Paul Easley - 421
The Teenager
The Problems of Youth - Mack Wayne Craig - 432
Influences for Good - Wyatt Sawyer - 443
The Benefits of Abilene Christian College
To the Church - Hulen Jackson - 451
To The Home - Robert S. Bell - 459
\u27To the Community - Louie Welch - 465
Expenses At Abilene Christian College - James C. Kerr - 469
The Graduate School at Abilene Christian College
What I Am Getting Now in the ACC Graduate Program - Harold Vanderpool - 475
How the ACC Graduate Program Has Stood Up - Everett Ferguson - 481
What the ACC Graduate Program Ought To Be - Frank Pack - 486
The Importance to the Church of the ACC Graduate Program A.R. Holton - 490
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Evaluation Research and Institutional Pressures: Challenges in Public-Nonprofit Contracting
This article examines the connection between program evaluation research and decision-making by public managers. Drawing on neo-institutional theory, a framework is presented for diagnosing the pressures and conditions that lead alternatively toward or away the rational use of evaluation research. Three cases of public-nonprofit contracting for the delivery of major programs are presented to clarify the way coercive, mimetic, and normative pressures interfere with a sound connection being made between research and implementation. The article concludes by considering how public managers can respond to the isomorphic pressures in their environment that make it hard to act on data relating to program performance.This publication is Hauser Center Working Paper No. 23. The Hauser Center Working Paper Series was launched during the summer of 2000. The Series enables the Hauser Center to share with a broad audience important works-in-progress written by Hauser Center scholars and researchers
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