Bacterial foraging algorithm with varying population

Most of evolutionary algorithms (EAs) are based on a fixed population. However, due to this feature, such algorithms do not fully explore the potential of searching ability and are time consuming. This paper presents a novel nature-inspired heuristic optimization algorithm: bacterial foraging algorithm with varying population (BFAVP), based on a more bacterially-realistic model of bacterial foraging patterns, which incorporates a varying population framework and the underlying mechanisms of bacterial chemotaxis, metabolism, proliferation, elimination and quorum sensing. In order to evaluate its merits, BFAVP has been tested on several benchmark functions and the results show that it performs better than other popularly used EAs, in terms of both accuracy and convergency.     

A laboratory method for studying zooplankton swimming behaviors

A laboratory method is presented for studying zooplankton swimming behaviors such as phototaxis and photokinesis. The method attempts to standardize laboratory conditions and to minimize the effects of several phenomena which modify zooplankton behavior. The role of angular light distribution in zooplankton behavior is discussed, and an apparatus which simulates a natural underwater light environment is described. The procedure minimizes the fluctuations in zooplankton swimming speed and vertical distribution that are caused by large light stimuli, noise, food deprivation, endogenous rhythms, and other factors. The experimental animals were viewed remotely with the aid of a light amplifier and video camera. A mathematical equation and computer program for calculating three-dimensional swimming speeds of zooplankton from video recordings are described in detail.     

Vocal types in crossbill populations (Loxia spp.) of Southwest Europe

The evolution of crossbills is one of the most fascinating topics in evolutionary ecology. Recent studies have shown an astonishing divergence in terms of vocalisation between morphologically quite similar crossbill populations in the Red/Common Crossbill complex (Loxia curvirostra) of North America and Europe. Some evidence even indicates the existence of “cryptic” species with different vocal types and bill sizes, which are adapted to different conifer species. However, there is so far no strong genetic evidence for the existence of separate species, although assortative mating occurs with respect to bill size. To understand the role of vocalisation in the speciation process of crossbill taxa, basic studies that assess the distribution of vocal types of crossbills and the use of different habitats and resources are needed. In our study, we investigated the occurrence of crossbill vocal types in Southwest Europe. In addition to the well-known vocal types described first by Robb (Dutch Birding 22:61–107, 2000) for the Benelux and Great Britain, we discovered at least six more vocal types in the Mediterranean area. Some vocal types were found exclusively in rather small areas, e.g. in the Pyrenees, the Sierra de Cazorla, Sierra de Javalambre and on Corsica, and appeared to be tightly linked to certain habitat types and pine species. Overall, vocal types in the Mediterranean had a more local occurrence than vocal types from northern populations, which were more widely distributed. This might reflect the nomadic behaviour of northern European crossbills, which feed, in contrast to Mediterranean crossbills, mostly on rather unstable food sources, especially spruce seeds. Furthermore, the vocal types of Mediterranean crossbills show at least some similarities to the vocal types of the rather sedentary crossbills of North Europe (L. pytyopsittacus, L. scotica), which are as well adapted to pine seeds. This might reflect a common ancestry of crossbills adapted for pines. We therefore suggest the existence of two main groups of crossbills in Europe: one group that is rather sedentary and feeds mainly on pine seeds (L. pytyopsittacus, L. scotica and the Mediterranean forms), and another group in Central, Northern and Eastern Europe that is highly nomadic and mostly feeds on spruce seeds (L. curvirostra). Further studies are needed to unravel the consistency of vocal types and the genetic relationship between the different forms, and to provide more evidence for the degree of assortative mating of crossbills with distinct vocalisation breeding in sympatry.     

La Dolce Vita in times of harshness: Prevalence of health-related behaviors during the great recession in Italy

The current work investigates the heterogeneous effect of the 2008 recession on health outcomes in the Italian population across the main geographic areas. Health outcomes were proxied by individual-level information on healthy/risky behaviors, such as individual fruit and vegetable consumption, frequency of bodyweight monitoring, smoking, and alcohol intake. These health outcomes were employed as dependent variables in the empirical model that included some socioeconomic individual aspects (e.g., age, gender, education, and income source), as well as consumer price index data for tobacco products, alcoholic beverages, and fruit and vegetables. In this work, we used twelve years of data (2005–2016) from the Italian Multipurpose Household Survey (MHS), which collects individual self-reported characteristics, augmented with information on unemployment rates at the regional level, as well as with consumer price indexes for the goods analyzed. The results indicated that the 2008 economic crisis lowered the probability that individuals engage in healthy behaviors, such as self-monitoring their bodyweight, mostly among individuals in northern and central areas. Likewise, the economic downturn increased the probability of smoking regardless of the geographic area, with a larger magnitude in individuals in northern and central areas, whose health outcomes were more impacted by the economic downturn than individuals living in the southern and island areas.     

领导信任对医院员工组织公民行为影响的实证研究

?????? 目的 探索领导信任对医院员工不同层面的组织公民行为产生影响。方法 对北京市6家公立医院进行问卷调查，采用结构方程模型对假设关系进行验证。结果 变革型领导的不同维度、领导信任对员工个体层面组织公民行为、群体层面组织公民行为和组织层面组织公民行为有相似的驱动关系，即愿景激励直接影响个体层面组织公民行为、群体层面组织公民行为和组织层面组织公民行为，而德行垂范、领导魅力和个性化关怀3个维度完全通过领导信任中介对个体层面组织公民行为、群体层面组织公民行为和组织层面组织公民行为产生影响。结论 领导信任在中层变革型领导对员工组织公民行为的影响中起到部分中介作用。     

Zooplankters as indicators of ecosystem health: past findings and future directions

Both acute (ingestion, respiration) and chronic bioassays (reproduction, survival) have been used to identify sources of pollutants. A mass-balance analysis suggests that acute tests be paired, using important indicator species asDaphnia, Ceriodaphnia and potentially others, to estimate the impact of contaminants upon the zooplankton community. Eventually groups of community bioassays may be combined to approximate an ecosystem bioassay. Hormesis or the stimulation of a physiological process by a compound which is toxic at high concentrations is characteristic of several bioassays; in this paper the ecotoxicology community is challenged to keep detailed records of the species, toxic compound, and physiological response involving hormesis in order to understand it; and ultimately to use it to simplify interpretation of bioassays. Life history characteristics of the cladoceran zooplankton, including early reproduction, high net reproductive rates, and the potential for many parthenogenetic generations with constant genotypes and low mutation rates make good choices for environmental bioassays. In contrast, high mutation rates of rotifers make them questionable choices. Five innovations, one or more of which may improve our ability to detect and identify pollutants, are suggested for ecotoxicologists using zooplankton. These include (a) the use of strains of known genotype; (b) determination of the genetic adaptation of clones to common toxins; (c) the use of common behaviors, including responses to light in detection of non-lethal chemicals at ambient levels; (d) record keeping on occurrence of cladoceran tumors; and (e) the determination of precise toxins responsible for the inhibition of zooplankton function and behavior.