277 research outputs found

    Effects of light and temperature on germination of Pyxidanthera brevifolia Wells (Diapensiaceae)

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    Pyxidanthera brevifolia is an evergreen semiwoody cushion plant endemic to the Sandhills of North and South Carolina, with the majority of populations occurring on Fort Bragg Military Reservation in North Carolina. Currently the species is listed as Endangered in North Carolina and is designated as a Species at Risk (SAR) by the US Department of Defense. Previous studies have suggested that seeds may not be viable because they failed to germinate under controlled conditions. Our objectives in this study were to attempt germination of Pyxidanthera brevifolia seeds, determine the best temperature conditions for germination, and understand more about germination requirements to aid in future restoration efforts. Using seeds that had been stored at room temperature for six months, we performed a germination experiment at the NCSU Phytotron with six treatments, all combinations of three temperature regimes (low (18 uC day / 14 uC night), medium (22/18 uC), and high (26/ 22 uC)) and two light conditions (light and dark). We monitored the experiment for 13 weeks, recording the number of seeds germinating per dish and the number of days to germination for seeds in each treatment. We found that Pxyidanthera brevifolia produces germinable seeds and that there are significant effects of light and temperature on germination. Highest germination occurred under low temperature and high light conditions (78%); the combination of high temperature and no light produced the lowest germination (6%). Seeds exposed to light germinated significantly earlier at the coolest temperature, compared to medium and high temperatures. These results indicate that it is possible to germinate seeds of this rare plant and suggest that germination of Pyxidanthera brevifolia likely occurs in late fall and is dependent on adequate light availability

    Measuring the capability to raise revenue process and output dimensions and their application to the Zambia revenue authority

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    The worldwide diffusion of the good governance agenda and new public management has triggered a renewed focus on state capability and, more specifically, on the capability to raise revenue in developing countries. However, the analytical tools for a comprehensive understanding of the capability to raise revenue remain underdeveloped. This article aims at filling this gap and presents a model consisting of the three process dimensions ‘information collection and processing’, ‘merit orientation’ and ‘administrative accountability’. ‘Revenue performance’ constitutes the fourth capability dimension which assesses tax administration’s output. This model is applied to the case of the Zambia Revenue Authority. The dimensions prove to be valuable not only for assessing the how much but also the how of collecting taxes. They can be a useful tool for future comparative analyses of tax administrations’ capabilities in developing countries.Die weltweite Verbreitung der Good-Governance- und New-Public-Management-Konzepte hat zu einer zunehmenden Konzentration auf staatliche Leistungsfähigkeit und, im Besonderen, auf die Leistungsfähigkeit der Steuererhebung in Entwicklungsländern geführt. Allerdings bleiben die analytischen Werkzeuge für ein umfassendes Verständnis von Leistungsfähigkeit unterentwickelt. Dieser Artikel stellt hierfür ein Modell vor, das die drei Prozess-Dimensionen „Sammeln und Verarbeiten von Informationen“, „Leistungsorientierung der Mitarbeiter“ und „Verantwortlichkeit der Verwaltung“ beinhaltet. „Einnahmeperformanz“ ist die vierte Dimension und erfasst den Output der Steuerverwaltung. Das mehrdimensionale Modell wird für die Analyse der Leistungsfähigkeit der Steuerbehörde Zambias (Zambia Revenue Authority) genutzt. Es erweist sich nicht nur für die Untersuchung des Wieviel, sondern auch des Wie des Erhebens von Steuern als wertvoll. Die vier Dimensionen können in Zukunft zur umfassenden und vergleichenden Analyse der Leistungsfähigkeit verschiedener Steuerverwaltungen in Entwicklungsländern genutzt werden

    The Third wave in globalization theory

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    This essay examines a proposition made in the literature that there are three waves in globalization theory—the globalist, skeptical, and postskeptical or transformational waves—and argues that this division requires a new look. The essay is a critique of the third of these waves and its relationship with the second wave. Contributors to the third wave not only defend the idea of globalization from criticism by the skeptics but also try to construct a more complex and qualified theory of globalization than provided by first-wave accounts. The argument made here is that third-wave authors come to conclusions that try to defend globalization yet include qualifications that in practice reaffirm skeptical claims. This feature of the literature has been overlooked in debates and the aim of this essay is to revisit the literature and identify as well as discuss this problem. Such a presentation has political implications. Third wavers propose globalist cosmopolitan democracy when the substance of their arguments does more in practice to bolster the skeptical view of politics based on inequality and conflict, nation-states and regional blocs, and alliances of common interest or ideology rather than cosmopolitan global structures

    Resistance to receptor-blocking therapies primes tumors as targets for HER3-homing nanobiologics

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    Resistance to anti-tumor therapeutics is an important clinical problem. Tumor-targeted therapies currently used in the clinic are derived from antibodies or small molecules that mitigate growth factor activity. These have improved therapeutic efficacy and safety compared to traditional treatment modalities but resistance arises in the majority of clinical cases. Targeting such resistance could improve tumor abatement and patient survival. A growing number of such tumors are characterized by prominent expression of the human epidermal growth factor receptor 3 (HER3) on the cell surface. This study presents a “Trojan-Horse” approach to combating these tumors by using a receptor-targeted biocarrier that exploits the HER3 cell surface protein as a portal to sneak therapeutics into tumor cells by mimicking an essential ligand. The biocarrier used here combines several functions within a single fusion protein for mediating targeted cell penetration and non-covalent self-assembly with therapeutic cargo, forming HER3-homing nanobiologics. Importantly, we demonstrate here that these nanobiologics are therapeutically effective in several scenarios of resistance to clinically approved targeted inhibitors of the human EGF receptor family. We also show that such inhibitors heighten efficacy of our nanobiologics on naïve tumors by augmenting HER3 expression. This approach takes advantage of a current clinical problem (i.e. resistance to growth factor inhibition) and uses it to make tumors more susceptible to HER3 nanobiologic treatment. Moreover, we demonstrate a novel approach in addressing drug resistance by taking inhibitors against which resistance arises and re-introducing these as adjuvants, sensitizing tumors to the HER3 nanobiologics described here

    Domain Organization of Long Signal Peptides of Single-Pass Integral Membrane Proteins Reveals Multiple Functional Capacity

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    Targeting signals direct proteins to their extra - or intracellular destination such as the plasma membrane or cellular organelles. Here we investigated the structure and function of exceptionally long signal peptides encompassing at least 40 amino acid residues. We discovered a two-domain organization (“NtraC model”) in many long signals from vertebrate precursor proteins. Accordingly, long signal peptides may contain an N-terminal domain (N-domain) and a C-terminal domain (C-domain) with different signal or targeting capabilities, separable by a presumably turn-rich transition area (tra). Individual domain functions were probed by cellular targeting experiments with fusion proteins containing parts of the long signal peptide of human membrane protein shrew-1 and secreted alkaline phosphatase as a reporter protein. As predicted, the N-domain of the fusion protein alone was shown to act as a mitochondrial targeting signal, whereas the C-domain alone functions as an export signal. Selective disruption of the transition area in the signal peptide impairs the export efficiency of the reporter protein. Altogether, the results of cellular targeting studies provide a proof-of-principle for our NtraC model and highlight the particular functional importance of the predicted transition area, which critically affects the rate of protein export. In conclusion, the NtraC approach enables the systematic detection and prediction of cryptic targeting signals present in one coherent sequence, and provides a structurally motivated basis for decoding the functional complexity of long protein targeting signals

    Maternal alcohol intake prior to and during pregnancy and risk of adverse birth outcomes: evidence from a British cohort

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    Background: Evidence is conflicting regarding the relationship between low maternal alcohol consumption and birth outcomes. This paper aimed to investigate the association between alcohol intake before and during pregnancy with birth weight and gestational age and to examine the effect of timing of exposure. Methods: A prospective cohort in Leeds, UK, of 1303 pregnant women aged 18–45 years. Questionnaires assessed alcohol consumption before pregnancy and for the three trimesters separately. Categories of alcohol consumption were divided into ≤2 units/week and >2 units/week with a non-drinking category as referent. This was related to size at birth and preterm delivery, adjusting for confounders including salivary cotinine as a biomarker of smoking status. Results: Nearly two-thirds of women before pregnancy and over half in the first trimester reported alcohol intakes above the Department of Health (UK) guidelines of ≤2 units/week. Associations with birth outcomes were strongest for intakes >2 units/week before pregnancy and in trimesters 1 and 2 compared to non-drinkers. Even women adhering to the guidelines in the first trimester were at significantly higher risk of having babies with lower birth weight, lower birth centile and preterm birth compared to non-drinkers, after adjusting for confounders (p<0.05). Conclusions: We found the first trimester to be the period most sensitive to the effect of alcohol on the developing fetus. Women adhering to guidelines in this period were still at increased risk of adverse birth outcomes. Our findings suggest that women should be advised to abstain from alcohol when planning to conceive and throughout pregnanc

    Solving Navigational Uncertainty Using Grid Cells on Robots

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    To successfully navigate their habitats, many mammals use a combination of two mechanisms, path integration and calibration using landmarks, which together enable them to estimate their location and orientation, or pose. In large natural environments, both these mechanisms are characterized by uncertainty: the path integration process is subject to the accumulation of error, while landmark calibration is limited by perceptual ambiguity. It remains unclear how animals form coherent spatial representations in the presence of such uncertainty. Navigation research using robots has determined that uncertainty can be effectively addressed by maintaining multiple probabilistic estimates of a robot's pose. Here we show how conjunctive grid cells in dorsocaudal medial entorhinal cortex (dMEC) may maintain multiple estimates of pose using a brain-based robot navigation system known as RatSLAM. Based both on rodent spatially-responsive cells and functional engineering principles, the cells at the core of the RatSLAM computational model have similar characteristics to rodent grid cells, which we demonstrate by replicating the seminal Moser experiments. We apply the RatSLAM model to a new experimental paradigm designed to examine the responses of a robot or animal in the presence of perceptual ambiguity. Our computational approach enables us to observe short-term population coding of multiple location hypotheses, a phenomenon which would not be easily observable in rodent recordings. We present behavioral and neural evidence demonstrating that the conjunctive grid cells maintain and propagate multiple estimates of pose, enabling the correct pose estimate to be resolved over time even without uniquely identifying cues. While recent research has focused on the grid-like firing characteristics, accuracy and representational capacity of grid cells, our results identify a possible critical and unique role for conjunctive grid cells in filtering sensory uncertainty. We anticipate our study to be a starting point for animal experiments that test navigation in perceptually ambiguous environments
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