Large-brained birds lay smaller but heavier clutches

The brain is among the most energetically costly organs in vertebrates,and thus trade-offs have been hypothesized to exert constraints on brain size evolution.The energy trade-off hypothesis(ETH) predicts that reducing the energy consumption of reproduction or other costly tissues should compensate for the cost of a large brain.Egg production in birds requires a large proportion of the total energy budget,and a clutch mass in some bird species can outweigh the body mass of the female.To date,this hypothesis has mainly been tested in mammals and ectothermic animals such as anurans and fishes.We collated data on adult brain size,body mass and eggproduction traits such as clutch size,egg mass and annual broods from published studies,and conducted a phylogenetic comparative test of the interplay between egg-production investment and brain size evolution across bird species.After controlling for phylogenetic relationships and body size,we find a negative correlation between brain size and clutch size across 1395 species,which favored ETH.However,when egg mass was integrated in models,positive associations were detected between brain size and mass of eggs(via egg mass,clutch mass and annual total egg mass).Our results suggest that brain size trades off against egg-production only via certain aspects(e.g.,clutch size).By contrast,a positive relationship between brain size and total egg reproduction(e.g.,clutch mass and annual total egg mass) implied increased total energy budget outweighing energy allocation across bird species.Our study shows that there is no general energy trade-off between brain size and eggreproduction investment,and suggests that brain size evolution follows mixed strategies across bird species.

SAR Imaging of Moving Target Based on Quadratic Phase Function

In this paper, a novel signal processing technique hasbeen developed to refocus moving targets image from their smeared responses in the Synthetic Aperture Radar (SAR) image according to the characteristics of the received signals for moving targets. Quadratic Phase Function is introduced to the parameters estimation for moving target echo and SAR imaging. Our method is available even under a low SNR environment and acquiring an exact SAR image of moving targets. The simulated results demonstrated the validity of the algorithm proposed.

Nest complexity correlates with larger brain size but smaller body mass across bird species

Amniotes differ substantially in absolute and relative brain size after controlling for allometry,and numerous hypotheses have been proposed to explain brain size evolution.Brain size is thought to correlate with processing capacity and the brain’s ability to support complex manipulation such as nest-building skills.The increased complexity of nest structure is supposed to be a measure of an ability to manipulate nesting material into the required shape.The degree of nest-structure complexity is also supposed to be associated with body mass,partly because small species lose heat faster and delicate and insulated nests are more crucial for temperature control of eggs during incubation by small birds.Here,we conducted comparative analyses to test these hypotheses by investigating whether the complexity of species-typical nest structure can be explained by brain size and body mass(a covariate also to control for allometric effects on brain size)across 1353 bird species from 147 families.Consistent with these hypotheses,our results revealed that avian brain size increases as the complexity of the nest structure increases after controlling for a significant effect of body size,and also that a negative relationship exists between nest complexity and body mass.

Direct-acting Antiviral-induced Transient Recovery of NK Cells in Early-stage Treatment of Chronic Hepatitis C Patients

Background and Aims:The rapid clearance of hepatitis C virus induced by direct-acting antivirals(DAAs)affects natural killer(NK)cells,but the reported results are not consistent,and the relative mechanism was unclear.This study focused on the dynamic changes of NK cells during and after DAA treatment and analyzed the reasons.Meth-ods:Peripheral blood from 35 chronic hepatitis C patients who were treated with DAAs were collected at baseline and weeks 1,2,4,12,and post-treatment week-12.The fre-quency,subset,and phenotype of NK cells were assayed by flow cytometry.Lactate dehydrogenase assays were used to evaluate the cytotoxicity of NK cells.Cytokine concentra-tions were measured with Luminex kits.Results:All pa-tients achieved a sustained viral response(SVR),and the NK cell frequencies were not changed significantly during DAA therapy.However,the cytotoxicity of NK cells recov-ered significantly early in week 1,and then continuously decreased below normal levels.The changes of genotypes including NKp30+,NKp46+,and NKG2A+NK cells were par-allel to NK function.The subset of CD56dim NK cells con-tinuously increased and did not return to normal even at 12 weeks after treatment.Interleukin(IL)-2,IL10,IL15,interferon-gamma,and tumor necrosis factor-alpha all in-creased after week 4,peaked at the end of therapy,and then exhibited varying degrees of reduction with time.Con-clusions:DAA treatment led to transient functional recov-ery of NK cells in the early stage of treatment,and then continuously decreased to below normal levels.Alterations of NK subsets,phenotypes,and the microenvironment may be involved in the changes.