¿Afecta la calidad del hábitat alimentario a la capacidad reproductiva de la garceta común, Egretta garzetta?

In order to understand the role of foraging habitat quality on fecundity parameters we measured habitat use, breeding parameters, and body condition of chicks in six colonies of Little Egrets in southern France. The foraging habitat available differed between colonies; it was mainly natural marshes around the Carrelet colony, agricultural lands (rice fields and dry crops) around the Agon colony, a mix of agricultural and natural lands around the Redon and Fiélouse colonies, a mix of natural and urbanised/industrial lands around the Palissade colony, and mainly cultivated and urbanised lands around the Chaumont colony. The habitat attractiveness to adult Little Egret breeding was higher for natural marshes than for other habitat types. Agricultural marshes (rice fields) came next. Other human–made habitats came last. Clutch size and body condition index of chicks did not differ between colonies. Brood size was influenced by both the association of the proportion of natural marshes in the foraging area and clutch size, and the association of clutch size and the total number of heron pairs in the colony. The effect of the proportion of natural marshes could not be distinguished from the effects of the colony size. The potential influence of other parameters not taken into account in this study is discussed.Con la finalidad de conocer el papel que ejerce la calidad del hábitat alimentario sobre los parámetros de fecundidad, se evaluaron el uso del hábitat, los parámetros reproductivos y las condiciones físicas de los polluelos de seis colonias de garceta común en el sur de Francia. El hábitat alimentario disponible variaba de unas colonias a otras, siendo principalmente marismas naturales en el entorno de la colonia de Carrelet, terrenos agrícolas (campos de arroz y cultivos de secano) alrededor de la colonia de Agon, una combinación de terrenos agrícolas y naturales alrededor de las colonias de Redon y Fiélouse, una combinación de terrenos naturales y urbanizados/industriales alrededor de la colonia de Palissade, y principalmente terrenos cultivados y urbanizados alrededor de la colonia de Chaumont. En la época de reproducción, los adultos de garceta común se sienten atraídos principalmente por las marismas naturales, en detrimento de otros tipos de hábitat. Las tierras agrícolas anegadas (campos de arroz) siguen en orden de preferencia, mientras los hábitats construidos por el hombre ocupan el último lugar. El tamaño de la puesta y el índice de estado físico de los polluelos no mostraron diferencias entre las colonias. El tamaño de la nidada estuvo influenciado tanto por la asociación de la proporción de marismas naturales en el hábitat alimentario y el tamaño de la puesta, como por la asociación del tamaño de la puesta y el número total de parejas de garzas de la colonia. El efecto de la proporción de marismas naturales no se puede diferenciar del ejercido por el tamaño de la colonia. Se discute también la influencia potencial de otros parámetros que no se han tenido en cuenta en este estudio

Live to cheat another day: bacterial dormancy facilitates the social exploitation of beta-lactamases

The breakdown of antibiotics by β-lactamases may be cooperative, since resistant cells can detoxify their environment and facilitate the growth of susceptible neighbours. However, previous studies of this phenomenon have used artificial bacterial vectors or engineered bacteria to increase the secretion of β-lactamases from cells. Here, we investigated whether a broad-spectrum β-lactamase gene carried by a naturally occurring plasmid (pCT) is cooperative under a range of conditions. In ordinary batch culture on solid media, there was little or no evidence that resistant bacteria could protect susceptible cells from ampicillin, although resistant colonies could locally detoxify this growth medium. However, when susceptible cells were inoculated at high densities, late-appearing phenotypically susceptible bacteria grew in the vicinity of resistant colonies. We infer that persisters, cells that have survived antibiotics by undergoing a period of dormancy, founded these satellite colonies. The number of persister colonies was positively correlated with the density of resistant colonies and increased as antibiotic concentrations decreased. We argue that detoxification can be cooperative under a limited range of conditions: if the toxins are bacteriostatic rather than bacteridical; or if susceptible cells invade communities after resistant bacteria; or if dormancy allows susceptible cells to avoid bactericides. Resistance and tolerance were previously thought to be independent solutions for surviving antibiotics. Here, we show that these are interacting strategies: the presence of bacteria adopting one solution can have substantial effects on the fitness of their neighbours

Digital Twin of a Network and Operating Environment Using Augmented Reality

We demonstrate the digital twin of a network, network elements, and operating environment using machine learning. We achieve network card failure localization and remote collaboration over 86 km of fiber using augmented reality

Can airborne ultrasound monitor bubble size in chocolate?

Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product

The practices of apartheid as a war crime: a critical analysis

The human suffering caused by the political ideology of apartheid in South Africa during the Apartheid era (1948-1994) prompted worldwide condemnation and a variety of diplomatic and legal responses. Amongst these responses was the attempt to have apartheid recognised both as a crime against humanity in the 1973 Apartheid Convention as well as a war crime in Article 85(4)(c) of Additional Protocol I. This article examines the origins, nature and current status of the practices of apartheid as a war crime and its possible application to the Israeli-Palestinian conflict

Quorum Sensing Inhibition Selects for Virulence and Cooperation in Pseudomonas aeruginosa

With the rising development of bacterial resistance the search for new medical treatments beyond conventional antimicrobials has become a key aim of public health research. Possible innovative strategies include the inhibition of bacterial virulence. However, consideration must be given to the evolutionary and environmental consequences of such new interventions. Virulence and cooperative social behaviour of the bacterium Pseudomonas aeruginosa rely on the quorum-sensing (QS) controlled production of extracellular products (public goods). Hence QS is an attractive target for anti-virulence interventions. During colonization, non-cooperating (and hence less virulent) P. aeruginosa QS-mutants, benefiting from public goods provided by wild type isolates, naturally increase in frequency providing a relative protection from invasive infection. We hypothesized that inhibition of QS-mediated gene expression removes this growth advantage and selection of less virulent QS-mutants, and maintains the predominance of more virulent QS-wild type bacteria. We addressed this possibility in a placebo-controlled trial investigating the anti-QS properties of azithromycin, a macrolide antibiotic devoid of bactericidal activity on P. aeruginosa, but interfering with QS, in intubated patients colonized by P. aeruginosa. In the absence of azithromycin, non-cooperating (and hence less virulent) lasR (QS)-mutants increased in frequency over time. Azithromycin significantly reduced QS-gene expression measured directly in tracheal aspirates. Concomitantly the advantage of lasR-mutants was lost and virulent wild-type isolates predominated during azithromycin treatment. We confirmed these results in vitro with fitness and invasion experiments. Azithromycin reduced growth rate of the wild-type, but not of the lasR-mutant. Furthermore, the lasR-mutant efficiently invaded wild-type populations in the absence, but not in the presence of azithromycin. These in vivo and in vitro results demonstrate that anti-virulence interventions based on QS-blockade diminish natural selection towards reduced virulence and therefore may increase the prevalence of more virulent genotypes in the Hospital environment. More generally, the impact of intervention on the evolution of virulence of pathogenic bacteria should be assessed

Aversive Learning in Honeybees Revealed by the Olfactory Conditioning of the Sting Extension Reflex

Invertebrates have contributed greatly to our understanding of associative learning because they allow learning protocols to be combined with experimental access to the nervous system. The honeybee Apis mellifera constitutes a standard model for the study of appetitive learning and memory since it was shown, almost a century ago, that bees learn to associate different sensory cues with a reward of sugar solution. However, up to now, no study has explored aversive learning in bees in such a way that simultaneous access to its neural bases is granted. Using odorants paired with electric shocks, we conditioned the sting extension reflex, which is exhibited by harnessed bees when subjected to a noxious stimulation. We show that this response can be conditioned so that bees learn to extend their sting in response to the odorant previously punished. Bees also learn to extend the proboscis to one odorant paired with sugar solution and the sting to a different odorant paired with electric shock, thus showing that they can master both appetitive and aversive associations simultaneously. Responding to the appropriate odorant with the appropriate response is possible because two different biogenic amines, octopamine and dopamine subserve appetitive and aversive reinforcement, respectively. While octopamine has been previously shown to substitute for appetitive reinforcement, we demonstrate that blocking of dopaminergic, but not octopaminergic, receptors suppresses aversive learning. Therefore, aversive learning in honeybees can now be accessed both at the behavioral and neural levels, thus opening new research avenues for understanding basic mechanisms of learning and memory

The pore structure and gating mechanism of K2P channels

K2P potassium channels are important regulators of cellular excitability. This study reveals that in contrast to most other K+ channels the primary gating mechanism in the K2P channel TREK-1 does not involve opening and closure of the cytoplasmic bundle crossing, but takes place close to or within the selectivity filter

Effect of heating rate on the crack formation during baking in carbon anodes used in aluminum industry

The quality of carbon anodes used in aluminum industry depends on the raw material properties and the manufacturing process parameters. It is one of the key factors directly related to the aluminum production cost. The degradation in anode quality such as crack formation increases the energy consumption, the environmental emissions, and the smelter’s overall operating cost. The objective of this work is to investigate the formation of cracks in several industrial green anode samples during baking at different heating rates and to determine the influence of this baking parameter on the crack formation. The samples were characterized before and after baking by measuring a number of physical properties (electrical resistivity, density, etc.) which define the final quality of the anode samples. Also, techniques based on ultra-sound and scanning electron microscopy were used to determine the extent of cracking after baking