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Search Results: 1 - 10 of 8429 matches for " Marie Dacke "
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Learning of Multi-Modal Stimuli in Hawkmoths
Anna Balkenius, Marie Dacke
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071137
Abstract: The hawkmoth, Manduca sexta, uses both colour and odour to find flowers when foraging for nectar. In the present study we investigated how vision and olfaction interact during learning. Manduca sexta were equally attracted to a scented blue coloured feeding target (multimodal stimulus) as to one that does not carry any scent (unimodal stimulus; visual) or to an invisible scented target (unimodal stimulus; odour). This naive attraction to multimodal as well as to unimodal stimuli could be manipulated through training. Moths trained to feed from a blue, scented multimodal feeding target will, when tested in a set-up containing all three feeding targets, select the multimodal target as well as the scented, unimodal target, but ignore the visual target. Interestingly, moths trained to feed from a blue, unimodal visual feeding target will select the visual target as well as the scented, multimodal target, but ignore the unimodal odour target. Our results indicate that a multimodal target is perceived as two separate modalities, colour and odour, rather than as a unique fused target. These findings differ from earlier studies of desert ants that perceive combined visual and odour signals as a unique fused stimulus following learning trials.
Fog-basking behaviour and water collection efficiency in Namib Desert Darkling beetles
Thomas N?rgaard, Marie Dacke
Frontiers in Zoology , 2010, DOI: 10.1186/1742-9994-7-23
Abstract: The beetles differ greatly in size. The largest P. cribripes has a dorsal surface area that is 1.39, 1.56, and 2.52 times larger than O. unguicularis, O. laeviceps, and S. gracilipes, respectively. In accordance with earlier reports, we found that the second largest O. unguicularis is the only one of the four beetles that assumes the head standing fog-basking behaviour, and that fog is necessary to trigger this behaviour. No differences were seen in the absolute amounts of fog water collected on the dorsal surface areas of the different beetles. However, data corrected according to the sizes of the beetles revealed differences. The better fog water harvesters were S. gracilipes and O. unguicularis while the large P. cribripes was the poorest. Examination of the elytra microstructures showed clear structural differences, but the elytra of all beetles were found to be completely hydrophobic.The differences in fog water harvesting efficiency by the dorsal surface areas of beetles with very different elytra surface structures were minor. We therefore conclude that the fog-basking behaviour itself is a more important factor than structural adaptations when O. unguicularis collect water from fog.The cold Benguela current runs along the South West African coast, creating one of the most arid habitats on earth; the Namib Desert [1]. Water is essential to all living organisms and this harsh environment presents a major challenge for all life forms. However, the cold coastal current not only suppresses rainfall over the desert, but is also the origin of fog that can reach as much as 100 km inland from the coast [2]. Fog brings water in the form of minute droplets that can deposit up to a litre of water per square metre on the mesh of an artificial fog screen during a day in the Namib Desert [3]. These fog events occur approximately 30 days per year in the inland desert [4], and represent a predictable source of water for the Namib Desert organisms [2].The Namib Desert has a r
Animal or Plant: Which Is the Better Fog Water Collector?
Thomas N?rgaard, Martin Ebner, Marie Dacke
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034603
Abstract: Occasional fog is a critical water source utilised by plants and animals in the Namib Desert. Fog basking beetles (Onymacris unguicularis, Tenebrionidae) and Namib dune bushman grass (Stipagrostris sabulicola, Poaceae) collect water directly from the fog. While the beetles position themselves optimally for fog water collection on dune ridges, the grass occurs predominantly at the dune base where less fog water is available. Differences in the fog-water collecting abilities in animals and plants have never been addressed. Here we place beetles and grass side-by-side in a fog chamber and measure the amount of water they collect over time. Based on the accumulated amount of water over a two hour period, grass is the better fog collector. However, in contrast to the episodic cascading water run-off from the grass, the beetles obtain water in a steady flow from their elytra. This steady trickle from the beetles' elytra to their mouth could ensure that even short periods of fog basking – while exposed to predators – will yield water. Up to now there is no indication of specialised surface properties on the grass leafs, but the steady run-off from the beetles could point to specific property adaptations of their elytra surface.
The Dung Beetle Dance: An Orientation Behaviour?
Emily Baird,Marcus J. Byrne,Jochen Smolka,Eric J. Warrant,Marie Dacke
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030211
Abstract: An interesting feature of dung beetle behaviour is that once they have formed a piece of dung into a ball, they roll it along a straight path away from the dung pile. This straight-line orientation ensures that the beetles depart along the most direct route, guaranteeing that they will not return to the intense competition (from other beetles) that occurs near the dung pile. Before rolling a new ball away from the dung pile, dung beetles perform a characteristic “dance,” in which they climb on top of the ball and rotate about their vertical axis. This dance behaviour can also be observed during the beetles' straight-line departure from the dung pile. The aim of the present study is to investigate the purpose of the dung beetle dance. To do this, we explored the circumstances that elicit dance behaviour in the diurnal ball-rolling dung beetle, Scarabaeus (Kheper) nigroaeneus. Our results reveal that dances are elicited when the beetles lose control of their ball or lose contact with it altogether. We also find that dances can be elicited by both active and passive deviations of course and by changes in visual cues alone. In light of these results, we hypothesise that the dung beetle dance is a visually mediated mechanism that facilitates straight-line orientation in ball-rolling dung beetles by allowing them to 1) establish a roll bearing and 2) return to this chosen bearing after experiencing a disturbance to the roll path.
Production of human polyclonal antibodies by transgenic animals  [PDF]
Louis-Marie Houdebine
Advances in Bioscience and Biotechnology (ABB) , 2011, DOI: 10.4236/abb.2011.23022
Abstract: Polyclonal antibodies collected from the blood of animals and humans experimentally immunised or spontaneously immunised respectively can be injected into patients to protect them against pathogens, toxins, tumours etc. This approach is severely limited by the availability of human polyclonal antibodies of interest. Moreover, polyclonal antibodies from animals are recognised as antigens by patients and are thus rapidly rejected and inactivated. To circumvent this problem, animals (essentially rabbits, chicken, pigs and cows) are being genetically engineered. Their immunoglobulin genes are being inactivated and the corresponding human immunoglobulin genes are being transferred to them. These animals will be immunized and it is expected that large amounts of pure human polyclonal antibodies will be extracted from their blood to be administered to patients. The possible acceptability problem of this approach is under a case study of the European Union Pegasus project.
Efficacy and tolerability of propolis special extract gh 2002 as a lip balm against herpes labialis: a randomized, double-blind three-arm dose finding study  [PDF]
Simona Holcová, Marie Hladiková
Health (Health) , 2011, DOI: 10.4236/health.2011.31010
Abstract: A dose-finding study was performed with respect to the clinical applicability and tolerability of three different concentrations of propolis special extract GH 2002 in a lip balm (0.1%, 0.5% and 1%). The trial was designed as a double-blind, randomized dermatological study in 150 outpatients with Herpes labialis. The primary parameter was the duration in days until painless incrustation in 50% or 90% of the patients (observable in 121 patients). Secondary parameters were local pain (assessed on a visual analogue scale), itching, burning and tension/ swelling on a verbal rating scale, and tolerability. Visits were performed on days 2/3, 5/6 and 8/9. Best efficacy results with shortest healing time (3.4 and 5.4 days in the 50th and 90th percentile, respectively; p = 0.008 vs. 1% and 0.09 vs. 0.1%) and good tolerability were observed with the 0.5% concentration. All three concentrations achieved highly significant therapeutic results in comparison with baseline values (p < 0.0005) for all secondary parameters as early as day 2/3. Analgesia was the most prominent effect for the patients. Conclusion: The 0.5 % concentration of propolis special extract GH 2002 in a lip balm was found to have the best risk-benefit ratio for the treatment of Herpes labialis.
Classroom Assessment Techniques: An Assessment and Student Evaluation Method  [PDF]
Dawn-Marie Walker
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.326136
Abstract: Some of the challenges that face Higher Education are how to ensure that assessment is meaningful and that feedback is prompt in order to promote learning. Another issue is how to provide lecturers with feedback regarding their efficacy, in a timely and non-judgmental manner. This paper proposes that Classroom Assessment Techniques (Angelo and Cross, 1993), maybe a good way of answering both of those issues. They are quick and easy tasks set within the lecture, which tests the student’s knowledge, providing an immediate opportunity for further elaboration if needed by the lecturer, therefore providing immediate feedback to the students. It also ensures that the lecturer has delivered the most salient messages, therefore also providing feedback to the lecturer.
Fuzzy Logic Strategy for Solving an Optimal Control Problem of Glucose and Insulin in Diabetic Human  [PDF]
Jean Marie Ntaganda
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.37052

This paper aims at the development of an approach integrating the fuzzy logic strategy for a glucose and insulin in diabetic human optimal control problem. To test the efficiency of this strategy, the author proposes a numerical comparison with the indirect method. The results are in good agreement with experimental data.

Hopf Bifurcation of a Two Delay Mathematical Model of Glucose and Insulin during Physical Activity  [PDF]
Jean Marie Ntaganda
Open Journal of Applied Sciences (OJAppS) , 2014, DOI: 10.4236/ojapps.2014.42006
Abstract: In this paper, we are interested in looking for Hopf bifurcation solutions for mathematical model of plasma glucose and insulin during physical activity. The mathematical model is governed by a system of delay differential equations. The algorithm for determining the critical delays that are appropriate for Hopf bifurcation is used. The illustrative example is taken for a 30 years old woman who practices regular three types of physical activity: walking, jogging and running fast.
Bank Characteristics and Procyclicality: A Theoretical Approach  [PDF]
Marie-Sophie Gauvin
Journal of Financial Risk Management (JFRM) , 2014, DOI: 10.4236/jfrm.2014.33007

The 2007-2008 crisis highlighted liquidity management troubles. We witness a real estate asset price boom during the pre-crisis period and a difficulty for banks to raise funding afterwards. Consequently, bank choices in response to the conduct of the monetary policy along the cycle can be studied. Despite usual financial accelerator, the excessive (lack of) confidence of banks in the upward (down) phase explains procyclical balance sheet movements. Moreover, the monetary policy effects on bank behaviors vary according to their initial specifications. From a theoretical point of view, this paper examines the response of the banking sector to monetary authorities impulses, in function of their initial characteristics. So, the paper highlights a theoretical model, based on accounting identities, in which banks are distinguished in different categories according to their level of capitalization and liquidity. The principal result is that the less capitalized and liquid banks have more procyclical behaviors.

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