Identification of Queen Sex Pheromone Components of the Bumblebee Bombus terrestris

We investigated the origin and chemical composition of the queen sex pheromone of the primitively eusocial bumblebee, Bombus terrestris (Apidae). Physiologically and behaviorally active compounds were identified by coupled gas chromatography electroantennography (GC-EAD), gas chromatography-mass spectrometry (GC-MS), and laboratory behavioral tests. In the behavioral assays, virgin queens frozen previously at −20°C were highly attractive to males. Dummies impregnated with surface and cephalic extracts obtained from virgin queens that had been frozen at −50°C were more attractive to males than odorless dummies. Male mating behavior was stimulated by components of cephalic secretions that are smeared onto the cuticle surface by the queen. Overall, 21 compounds present in surface and cephalic extracts evoked electroantennographic responses in male antennae. These included saturated and unsaturated fatty acids, ethyl- and methyl esters of the fatty acids, heptacosene, 2-nonanone, and geranyl geraniol. A blend of synthetic versions of these compounds elicited typical male mating behavior. Since solvent-impregnated dummies were approached by the males, but did not release copulatory behavior, visual cues may be important in the initial step of stimulating male mating behavior. Close-range olfactory signals are more important for releasing male mating behavior as well as for species recognition. In further behavioral assays, the attractiveness of a frozen virgin queen decreased as the storage time at −20°C increased from 2 hr to 1 d. Therefore, the chemical composition of the sex pheromone may change during freezing as behaviorally active compounds may decompose.     

Optimal orientation in flows: providing a benchmark for animal movement strategies

Animal movements in air and water can be strongly affected by experienced flow. While various flow-orientation strategies have been proposed and observed, their performance in variable flow conditions remains unclear. We apply control theory to establish a benchmark for time-minimizing (optimal) orientation. We then define optimal orientation for movement in steady flow patterns and, using dynamic wind data, for short-distance mass movements of thrushes (Turdus sp.) and 6000 km non-stop migratory flights by great snipes, Gallinago media. Relative to the optimal benchmark, we assess the efficiency (travel speed) and reliability (success rate) of three generic orientation strategies: full compensation for lateral drift, vector orientation (single-heading movement) and goal orientation (continually heading towards the goal). Optimal orientation is characterized by detours to regions of high flow support, especially when flow speeds approach and exceed the animal''s self-propelled speed. In strong predictable flow (short distance thrush flights), vector orientation adjusted to flow on departure is nearly optimal, whereas for unpredictable flow (inter-continental snipe flights), only goal orientation was near-optimally reliable and efficient. Optimal orientation provides a benchmark for assessing efficiency of responses to complex flow conditions, thereby offering insight into adaptive flow-orientation across taxa in the light of flow strength, predictability and navigation capacity.     

Non-metropolitan Growth Potential of Western Cape Municipalities

This paper provides a brief overview of the relevant post-2000 South African policy for regional (provincial) spatial development within the context of the quantitative findings of a study conducted on the growth potential of non-metropolitan settlements in the Western Cape. The findings are presented at municipal level. Five indices (social needs, economic, physical environment, infrastructure and institutional) and 69 indicators were used to determine development potential and social needs for the 24 local municipalities and three district management areas in the province. The potential indicators for each index were subjected to a factor analysis to select appropriate core indicators for inclusion in the composite indices. Based on their overall performance in the various indices, the municipalities were classified into three categories??high, medium and low. The study results prioritise areas according to their developmental potential and social needs at municipal level.     

万桥园

<正>序生命之路——致"万桥园"每座园林都有一个故事。它们是诗,在诉说。我们的园林讲述的是生命的故事,人的生命之路。这条路跌宕起伏,忍辱负重,讲述了忧愁河上的众桥。在这座园林中,生命是一条绵延不绝的蜿蜒小路,更恍如一座迷宫。     

Fatty acid profile and affective dysregulation in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder with a high co-occurrence with affective dysregulation. Affective disorders have been associated with specific changes in the PUFA and cholesterol profile. In IBS, similar changes may be present as have been reported in patients with affective disorders. This exploratory study investigates (i) the level of affective dysregulation (AD) in IBS patients and healthy controls; (ii) PUFA and cholesterol profiles in IBS patients compared with controls; and (iii) associations between PUFA and cholesterol parameters with the level of AD. Blood samples were obtained for determination of the FA composition of plasma phospholipids and serum cholesterol in 23 diarrheapredominant IBS patients and 23 healthy matched controls. AD was scored using the Symptom Check List depression scale, the Hospital Anxiety and Depression Scale, and the Hamilton Depression Rating Scale. The level of AD was higher in IBS patients compared with controls. PUFA and cholesterol profiles did not differ significantly between groups. Total n−3 PUFA and cholesterol were significantly negatively associated and the ratio of n−6 to n−3 PUFA and the ratio of arachidonic acid to EPA were significantly positively associated with the level of AD. The findings of the present study reveal that AD was higher in IBS patients compared with healthy controls and that changes in PUFA and cholesterol profiles were significantly associated with the level of AD. These results warrant further studies regarding the role of PUFA and cholesterol status in the co-occurrence of AD and functional gastrointestinal disorders.     

Coordination by design and the price of autonomy

We consider a multi-agent planning problem as a set of activities that has to be planned by several autonomous agents. In general, due to the possible dependencies between the agents’ activities or interactions during execution of those activities, allowing agents to plan individually may lead to a very inefficient or even infeasible solution to the multi-agent planning problem. This is exactly where plan coordination methods come into play. In this paper, we aim at the development of coordination by design techniques that (i) let each agent construct its plan completely independent of the others while (ii) guaranteeing that the joint combination of their plans always is coordinated. The contribution of this paper is twofold. Firstly, instead of focusing only on the feasibility of the resulting plans, we will investigate the additional costs incurred by the coordination by design method, that means, we propose to take into account the price of autonomy: the ratio of the costs of a solution obtained by coordinating selfish agents versus the costs of an optimal solution. Secondly, we will point out that in general there exist at least two ways to achieve coordination by design: one called concurrent decomposition and the other sequential decomposition. We will briefly discuss the applicability of these two methods, and then illustrate them with two specific coordination problems: coordinating tasks and coordinating resource usage. We also investigate some aspects of the price of autonomy of these two coordination methods.     

Modeling and development of an ANN-based smart pressure sensor in a dynamic environment

In many engineering applications, a capacitive pressure sensor (CPS) is placed in a dynamic environment in which the temperature variation is quite large. Since the response characteristics of a CPS are highly nonlinear and temperature dependent, in such situations, complex signal processing techniques are needed to obtain correct readout of the applied pressure. We have proposed an artificial neural network (ANN)-based smart capacitive pressure sensor, whose response characteristics can be estimated within an accuracy of ±1% error over a wide variation of temperature starting from −50°C to 150°C. This modeling scheme automatically takes care of all the nonidealities, such as, nonlinearity, offset, gain and temperature dependence, of the sensor. A novel idea of automatic collection of temperature information and its feeding into the ANN model is also proposed. In the practical implementation of this scheme, the hardware complexity poses a serious impairment. Since the tanh() functions are needed for implementation in the ANN-based model, to reduce the hardware requirement, we provide a simple scheme for computation of tanh(). Sensitivity analysis of the model with respect to the finite word-length constraint on the final stored weight values, and number of terms used in the implementation of tanh() function, have been carried out. A microcontroller-based implementation scheme for the ANN-based model is also suggested.     

‘Green’ synthesis and optical properties of silver–chitosan complexes and nanocomposites

Silver nanoparticles were synthesized in a chitosan biopolymer by an in situ ‘green’ chemical procedure, using d-glucose as the reducing agent. The reaction intermediates (silver–chitosan complexes) as well as the obtained nanocomposites were investigated using transmission electron microscopy, UV–vis, FTIR and photoluminescence spectroscopy. The theoretical analysis of the UV–vis absorption of the Ag–chitosan complexes suggested that the significant contribution to the complex spectrum arises from clusters of silver containing 4–9 atoms. The absorption spectrum of the nanocomposite exhibited a strong surface plasmon resonance band at 406 nm. The photoluminescence behavior of the pure chitosan, the silver–chitosan complexes and the nanocomposites were discussed in terms of morphology and silver weight content.