329 research outputs found
Inoculating an agile company with user-centred design: an empirical study
We present an empirical study on facilitating the adoption of user-centred design (UCD) in small Agile companies. To this end, we introduced a curated set of qualitative design practices in an Agile organisation, engaging developers in a lightweight series of workshops. Our results suggest that the approach followed enhanced internal communication and promoted a concrete shift towards a more user-centred perspective. However, the presence of a predominant non-Agile customer seems to have limited potential benefits. © The Author(s) 2017
Computational Methodologies and Physical Insights into Electronic Energy Transfer in Photosynthetic Light-Harvesting Complexes
We examine computational techniques and methodologies currently in use to
explore electronic excitation energy transfer in the context of
light-harvesting complexes in photosynthetic antenna systems, and comment on
some new insights into the underlying physics. Advantages and pitfalls of these
methodologies are discussed, as are some physical insights into the
photosynthetic dynamics. By combining results from molecular modelling of the
complexes (structural description) with an effective non-equilibrium
statistical description (time evolution), we identify some general features,
regardless of the particular distribution in the protein scaffold, that are
central to light-harvesting dynamics and, that could ultimately be related to
the high efficiency of the overall process. Based on these general common
features, some possible new directions in the field are discussed.Comment: Invited Perspective Article for Phys. Chem. Chem. Phy
Larvicidal activity of metabolites from the endophytic Podospora sp. against the malaria vector Anopheles gambiae
In a screening for natural products with mosquito larvicidal activities, the endophytic fungus Podospora sp. isolated from the plant Laggera alata (Asteraceae) was conspicuous. Two xanthones, sterigmatocystin (1) and secosterigmatocystin (2), and an anthraquinone derivative (3) 13-hydroxyversicolorin B were isolated after fermentation on M2 medium. These compounds were characterised using spectroscopic and X-ray analysis and examined against third instar larvae of Anopheles gambiae. The results demonstrated that compound 1 was the most potent one with LC50 and LC90 values of 13.3 and 73.5 ppm, respectively. Over 95% mortality was observed at a concentration 100 ppm after 24 h. These results compared farvourably with the commercial larvicide pylarvex® that showed 100% mortality at the same concentration. Compound 3 was less potent and had an LC50 of 294.5 ppm and over 95% mortality was achieved at a concentration of 1,000 ppm. Secosterigmatocystin (2) revealed relatively weak activity and therefore LC values were not determined
Seasonal changes in patterns of gene expression in avian song control brain regions.
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Photoperiod and hormonal cues drive dramatic seasonal changes in structure and function of the avian song control system. Little is known, however, about the patterns of gene expression associated with seasonal changes. Here we address this issue by altering the hormonal and photoperiodic conditions in seasonally-breeding Gambel's white-crowned sparrows and extracting RNA from the telencephalic song control nuclei HVC and RA across multiple time points that capture different stages of growth and regression. We chose HVC and RA because while both nuclei change in volume across seasons, the cellular mechanisms underlying these changes differ. We thus hypothesized that different genes would be expressed between HVC and RA. We tested this by using the extracted RNA to perform a cDNA microarray hybridization developed by the SoNG initiative. We then validated these results using qRT-PCR. We found that 363 genes varied by more than 1.5 fold (>log(2) 0.585) in expression in HVC and/or RA. Supporting our hypothesis, only 59 of these 363 genes were found to vary in both nuclei, while 132 gene expression changes were HVC specific and 172 were RA specific. We then assigned many of these genes to functional categories relevant to the different mechanisms underlying seasonal change in HVC and RA, including neurogenesis, apoptosis, cell growth, dendrite arborization and axonal growth, angiogenesis, endocrinology, growth factors, and electrophysiology. This revealed categorical differences in the kinds of genes regulated in HVC and RA. These results show that different molecular programs underlie seasonal changes in HVC and RA, and that gene expression is time specific across different reproductive conditions. Our results provide insights into the complex molecular pathways that underlie adult neural plasticity
Neospora caninum and Toxoplasma gondii serodiagnosis in human immunodeficiency virus carriers
Keys and seats: Spatial response coding underlying the joint spatial compatibility effect
The effect of social context on the use of visual information
Social context modulates action kinematics. Less is known about whether social context also affects the use of task relevant visual information. We tested this hypothesis by examining whether the instruction to play table tennis competitively or cooperatively affected the kind of visual cues necessary for successful table tennis performance. In two experiments, participants played table tennis in a dark room with only the ball, net, and table visible. Visual information about both players’ actions was manipulated by means of self-glowing markers. We recorded the number of successful passes for each player individually. The results showed that participants’ performance increased when their own body was rendered visible in both the cooperative and the competitive condition. However, social context modulated the importance of different sources of visual information about the other player. In the cooperative condition, seeing the other player’s racket had the largest effects on performance increase, whereas in the competitive condition, seeing the other player’s body resulted in the largest performance increase. These results suggest that social context selectively modulates the use of visual information about others’ actions in social interactions
On the physical mechanism underlying Asymptotic Safety
We identify a simple physical mechanism which is at the heart of Asymptotic
Safety in Quantum Einstein Gravity (QEG) according to all available effective
average action-based investigations. Upon linearization the gravitational field
equations give rise to an inverse propagator for metric fluctuations comprising
two pieces: a covariant Laplacian and a curvature dependent potential term. By
analogy with elementary magnetic systems they lead to, respectively, dia- and
paramagnetic-type interactions of the metric fluctuations with the background
gravitational field. We show that above 3 spacetime dimensions the
gravitational antiscreening occurring in QEG is entirely due to a strong
dominance of the ultralocal paramagnetic interactions over the diamagnetic ones
that favor screening. (Below 3 dimensions both the dia- and paramagnetic
effects support antiscreening.) The spacetimes of QEG are interpreted as a
polarizable medium with a "paramagnetic" response to external perturbations,
and similarities with the vacuum state of Yang-Mills theory are pointed out. As
a by-product, we resolve a longstanding puzzle concerning the beta function of
Newton's constant in 2+{\epsilon} dimensional gravity.Comment: 43 pages, 8 figures; clarifying remarks added; to appear in JHE
Active extravasation of contrast within the hemorrhage (spot sign): a multidetector computed tomography finding that predicts growth and a worse prognosis in non-traumatic intracerebral hemorrhage
Evolving Synaptic Plasticity with an Evolutionary Cellular Development Model
Since synaptic plasticity is regarded as a potential mechanism for memory formation and learning, there is growing interest in the study of its underlying mechanisms. Recently several evolutionary models of cellular development have been presented, but none have been shown to be able to evolve a range of biological synaptic plasticity regimes. In this paper we present a biologically plausible evolutionary cellular development model and test its ability to evolve different biological synaptic plasticity regimes. The core of the model is a genomic and proteomic regulation network which controls cells and their neurites in a 2D environment. The model has previously been shown to successfully evolve behaving organisms, enable gene related phenomena, and produce biological neural mechanisms such as temporal representations. Several experiments are described in which the model evolves different synaptic plasticity regimes using a direct fitness function. Other experiments examine the ability of the model to evolve simple plasticity regimes in a task -based fitness function environment. These results suggest that such evolutionary cellular development models have the potential to be used as a research tool for investigating the evolutionary aspects of synaptic plasticity and at the same time can serve as the basis for novel artificial computational systems
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