Harmonics in the Squirrel Cage Induction Motor,Analytic Calculation Part Ⅱ:Synchronous Parasitic Torques,Radial Magnetic Forces

The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field,as well as the synchronous parasitic torques,radial magnetic forces have been discussed in great detail in the literature,but always separately,for a long time.However,systematization of the phenomenon still awaits.Therefore,it is worth summarizing the completeness of the phenomena in a single study–with a new approach at the same time-in order to reveal the relationships between them.The role of rotor slot number is emphasized much more than before.New formulas derived for both synchronous torques and radial magnetic forces are used for further investigation.It will be shown that both phenomena in subject must be treated together.Formulas will be provided to take into account attenuation.Design guide will be provided to avoid dangerous rotor slot numbers.It will be shown that the generation of synchronous torques and radial magnetic forces do not depend–in this new approach-on the slot combination,but on the rotor slot number itself.

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation-Part Ⅰ: Differential Leakage, Attenuation, Asynchronous Parasitic Torques

The magnetic field generated in the air gap of the cage asynchronous machine and the harmonics of the magnetomotive forces creating that magnetic field, as well as the related differential leakage, attenuation, asynchronous parasitic torques have been discussed in great detail in the literature, but always separately, for a long time. However, systematization of the phenomenon still awaits. Therefore, it is worth summarizing the completeness of the phenomena in a single study – with a new approach at the same time-in order to reveal the relationships between them. The role of rotor slot number is emphasized much more than before. An existing, commonly used, but still impractical basic figure has been modified to more clearly demonstrate the response of the rotor for the harmonics of the stator. The need to treat differential leakage, asynchronous parasitic torques and attenuation together will be demonstrated: new formula for asynchronous parasitic torque is derived;the long-used characteristic curves for differential leakage and attenuation used separately so far was merged into one, correct curve in order to provide a correct design guide for the engineers.

Evaluation of Soybean Genotypes (Glycine max L. Merr.) Susceptibility to Parasitic Nematodes in Western Part of Burkina Faso

Parasitic nematodes have been reported as one of the major constraints to soybean production worldwide. The majority of nematodes are so-called “free-living” and feed mainly on bacteria, fungi, protozoa and other nematodes. In Burkina Faso, the presence of parasitic nematodes has been reported in crops such as rice and sorghum. The objective of this study was to identify the genera and species of nematodes associated with soybean production in Burkina Faso. Investigations were carried out on 24 genotypes of a medium-maturity group of soybean at the Farako-Ba research station. Soil samples were taken from the trial soil before its installation. At harvest, soil samples with roots were taken from each genotype in the elementary plots. The composite sample is represented by 4 lots of soil samples with roots. Extractions and counts of nematodes were performed on the different lots. In total, 7 genera of plant-parasitic nematodes associated with soybean were identified. Among these genera, Pratylenchus (100% of infected genotypes), Helicotylenchus (97.28%) and Scutellonema (94.44%) were the most prevalent in terms of frequency and abundance. Some soybean genotypes were less susceptible to the genus Pratylenchus is known to be highly pathogenic in soybean. These were mainly the genotypes TGX2025-10E, TGX2023-3E and TGX2025-14E.

Harmonics in the Squirrel Cage Induction Motor Analytic Calculation Part III: Influence on the Torque-speed Characteristic

The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.

Yr5-virulent races of Puccinia striiformis f.sp.tritici possess relative parasitic fitness higher than current main predominant races and potential risk

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici(Pst),is one of the most destructive fungal diseases of wheat,and seriously threatens safe production of the crop worldwide.In China,new races historically appeared and rapidly developed to be predominant races and have resulted in ineffectiveness and replacement of wheat resistance cultivars as well as massive reduction in yield.In the present study,the relative parasitic fitness of the two newlyemerged Yr5-virulent races(TSA-6 and TSA-9)were compared with those of four currently predominant Chinese races(CYR31,CYR32,CYR33,and CYR34)based on evaluation on 10 Chinese wheat cultivars.As a result,there were significant differences in the relative parasitic fitness parameters among overall tested races based on multiple comparison(LSD)analysis(P<0.05).The principal component analysis(PCA)of overall parasitic fitness parameters indicated that the sporulation ability,infection and spore survivability,expansion capacity,and potential pathogenicity were the most important parasitic fitness attributes of the tested races.Based on the establishment of extracted three principal components and a comprehensive factor score mathematical models,evaluations of the parasitic fitness attributes of tested races showed that the level of relative parasitic fitness of the tested six races was:CYR32(1.15)>TSA-9(0.95)>TSA-6(0.92)>CYR34(0.29)>CYR31(–1.54)>CYR33(–1.77).The results indicated that two Yr5-virulent races TSA-9 and TSA-6 possessed relative parasitic fitness higher than races CYR34,CYR31,and CYR33,but lower than race CYR32,and have potential risks in developing to be predominant races.Therefore,continual monitoring of both Yr5-virulent races,and their variants is needed.The use of wheat cultivars(lines)with Yr5 resistance gene singly in wheat breeding is essential for being avoided,and is suggested to combine with other effective stripe rust resistance genes.

Do brood parasitic Common Cuckoos develop brood patches during the breeding season?

Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,vascularization,and edema.However,little is known about whether avian brood parasites that do not incubate their eggs exhibit brood patch development during the breeding season.In this study,we measured the size of the ventral apterium in 114 Common Cuckoos(Cuculus canorus)captured in the field throughout the breeding season and examined the appearance of the ventral apterium to confirm the development of brood patches.We also examined whether morphological traits and various factors correlated with the size of the ventral apterium(sternal apterium and abdominal apterium)and how it changed during the breeding season.We found no clear signs of brood patch development in Common Cuckoos captured throughout the breeding season,indicating that they likely did not develop brood patches on the ventral apterium during this period.We also found that ventral apterium size was positively correlated with wing length and body weight.In addition,Common Cuckoos with newly growing feathers on the boundary of the ventral apterium with pteryla were frequently observed as seasons progressed to the end.In conclusion,Common Cuckoos exhibit neither brood patch development nor the vestigial characteristics of ancestral brood patches,except for the growth of feathers on boundary the ventral apterium.Further studies examining brood patches across different groups of avian brood parasites are valuable for enhancing our understanding of the developmental and physiological adaptations of avian brood parasites.

Taxonomic Study of Five Parasitic Polypores of the Hymenochaetaceae Family of TIN Vegetation in Western Burkina Faso

The aim of this work is to inventory and study the lignicolous parasitic macrofungi of the Tin plant formation. The mycological outings from July to September 2018 and 2019, collected forty-four (44) basidiomes through a random sampling device over an area of 40,000 m2 including 1000 m long by 40 m2 wide. The standard methods and techniques used in mycology for taxonomic studies were used to describe and classify the carpophores collected in three families: Hymenochaetaceae, Ganodermataceae and Polyporaceae, into eight genera: Onnia (4.55%), Amauroderma (4.55%), Ganoderma (20.45%), Phellinus (52.27%), Inonotus (4.55%), Phellinopsis (6.82%), Grammothele (2.27%) and Trametes (4.55%). The genera Phellinus and Ganoderma were the most abundant. Finally, eight species were identified: Inonotus cf. ochroporus, Inonotus cf. pachyphloeus, Phellinus cf. cryptarum, Phellinus cf. hartigii, Phellinus cf. hippophaecola;Phellinus cf. robustus, Phellinus cf. igniarius, et Amauroderma cf. fasciculatum. Seven fungal species belong to the family Hymenochaetaceae and only the species Amauroderma cf. fasciculatum is a Ganodermataceae. However, all these fungal species are shown to be parasites of trunks and/or branches of the following woody: Parkia biglobosa (50%), Anogeissus leiocarpus (25%), Annona senegalensis (12.5%) and Mangifera indica (12.5%). Authors attest that the presence of phytoparasitic polypores in a plant formation is an indicator of aging hence the urgency to put in place the appropriate measures to safeguard and restore Tin’s plant formation.

A review of selected parasitic plants in Nigeria:converting harms to benefits

Parasitic plants are challenging to agricultural crops and forestry development,which are sources of major revenues in several countries,including Nigeria.Nevertheless,parasitic plants are important to human society as they have an abundance of bioactive compounds with pharmacological relevance.Thus,it becomes expedient to know the benefits of these plants and potential means of management.This review discusses four selected parasitic plants in Nigeria,namely Viscum album,Striga hermonthica,Tapinanthus bangwensis and Cuscuta campestris.Relevant information about their pharmacological relevance and biocontrol was obtained from credible databases,including the National Library of Medicine,SCOPUS,and Google Scholar.The review showed that all four plants have been extensively studied for their antioxidant and antitumor properties.Also,antimicrobial and anti-inflammatory activities are common pharmacological values among parasitic plants.These are largely due to the presence of abundant beneficial classes of phytocompounds.Furthermore,there is an increasing number of biocontrol studies on the use of microorganisms,such as Phaeobotryosphaeria visci,Sphaeropsis visci,Pandoraea pulminicol,Colletotrichum gloeosporioides,and Fusarium oxysporum in controlling and managing these seemingly disastrous plants.It is hoped that this review will spur further studies into the conservation and proper management of parasitic plants using strategically developed biocontrol.

Cadmium(Cd)exposure through Hyphantria cunea pupae reduces the parasitic fitness of Chouioia cunea:A potential risk to its biocontrol efficiency

Heavy metal contamination has been regarded as an environmental variable that affects the efficiency of pest biological control,but the parasitic fitness of parasitoids under heavy metal stress is poorly understood.Herein,the effect of Cd exposure through the host pupa of Hyphantria cunea on the parasitic fitness of Chouioia cunea was investigated,and the mechanism by which Cd exposure affects the interaction between H.cunea and C.cunea from the perspective of innate immunity in host insect and the oxidative status in the parasitoid offspring was explored.Our results indicated that Cd can be transferred from the H.cunea pupae to the parasitoid offspring,and the transfer coefficient reflected biological amplification.There were no significant differences in the rates of parasitism success and offspring emergence between the untreated and Cd-treated groups.However,after parasitizing Cd-accumulated pupae,the parasitic fitness of offspring wasps(e.g.,the number,individual size and life span)decreased significantly.Under Cd exposure,the cellular and humoral immunity of H.cunea pupae decreased significantly.Compared with the untreated group,the H_(2)O_(2)content of parasitoid offspring in the Cd-treated group was significantly increased.Cd exposure significantly inhibited superoxide dismutase activity in parasitoid offspring,but the contents of ascorbic acid and glutathione were significantly increased by Cd stress.Taken together,these results indicate that Cd exposure reduces the cyclic utilization efficiency of C.cunea on H.cunea pupae.The oxidative status of parasitoid offspring triggered by Cd exposure could be responsible for the reduced parasitic fitness of C.cunea on Cd-accumulated H.cunea pupae.

Unveiling the parasitic-reaction-driven surface reconstruction in Ni-rich cathode and the electrochemical role of Li_(2)CO_(3)

Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energydensity lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li_(2)CO_(3) impurity content on LiNi_(0.83)Mn_(0.1)Co_(0.07)O_(2) cathodes using air, tank-air, and O_(2) synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li_(2)CO_(3) impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li_(2)CO_(3) content and severe performance deterioration of Ni83 cathodes.The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Nirich cathodes and prepares us for searching for rational strategies.

A novel method to collect sperm from brood parasitic cuckoos:Urodeum stimulation(UroS)method

Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.

Prevalence and Sensitization and Intestinal Parasitic Infestation of Vernal Keratoconjunctivitis in School Children of Kinshasa

Background: There is no study that estimates the prevalence of vernal keratoconjunctivitis and the association between vernal keratoconjunctivitis and intestinal parasitic infestation in our setting. Purpose: This study aimed to estimate the vernal keratoconjunctivitis prevalence, describe the profile of sensitization and determine the association between vernal keratoconjunctivitis disease and intestinal parasitic infestation in school children of Kinshasa during the scholar year from 2022 to 2023. Methods: An observational, cross-sectional study was performed from September 2022 to June 2023. The children with vernal keratoconjunctivitis were recruited by using the four-stage probability sampling technique. Children attending in the school children of Kinshasa with vernal keratoconjunctivitis were enrolled in the classroom and underwent a clinical examination and skin prick test for 11 allergens and stool examination direct with microscope in the Laboratory. Data were entered in Microsoft Sheets using SPSS version 20.0. The Chi-square test was used to compare the sex, age groups, home environment (grow trees and/or flowers around the yard), dampness in the house, keeping pets (cat and/or dog), number of people per household, number of people sharing a bedroom and intestinal parasitic infestation. The significant level was set to a value of p Results: A total of 28,800 students from four-stage probabilist sampling technique in school of Kinshasa were included, and 2100 students had symptoms according to the vernal keratoconjunctivitis-related symptom questionnaire. Children with vernal keratoconjunctivitis were enrolled and the mean age ± standard was 7.2 ± 3.7 years, with a prevalence of 7.2% and gender was three boys for one girl. All vernal keratoconjunctivitis children recruited in urban and rural part had 33.1% positive skin prick test (SPT) and 67.9% showed polysensitization. Children an urban part was more sensitized than rural respectively with Dermatophagoides pteronyssinus 28.1% vs 28.9%, p = 0.00001, Blomia tropicalis. 15.9% vs 14.9%, p = 0.00001 and cockroach 12% vs 13%, p = 0.00001 in both parts. Vernal keratoconjunctivitis children in rural part were more affected to the intestinal parasite than urban with Ascaris lumbricoides 14% vs 18.3%, p = 0.0006, followed by Ancylostoma duodenale 9.5% vs 12.5%, p = 0.003, Anguillule 7.9% vs 10.1%, p = 0.001, Oxyure 5.7% vs 8.2%, p = 0.0001 and Trichuris trichiura 2.6% vs 3.3%, p = 0.0009. Conclusion: This study outlines that the prevalence of vernal keratoconjunctivitis was 7.2% and 33.1% of children attending for vernal keratoconjunctivitis in school children had a positive skin prick test to at least one allergen, in particular for Dermatophagoides pteronyssinus, Blomia tropicalis and cockroach. The most common intestinal parasitic infestation was Ascaris lumbricoides, Ancylostoma duodenale, Anguillule and Trichuris trichiura.

An Electrochemical Perspective of Aqueous Zinc Metal Anode

Based on the attributes of nonflammability,environmental benignity,and cost-effectiveness of aqueous electrolytes,as well as the favorable compatibility of zinc metal with them,aqueous zinc ions batteries(AZIBs)become the leading energy storage candidate to meet the requirements of safety and low cost.Yet,aqueous electrolytes,acting as a double-edged sword,also play a negative role by directly or indirectly causing various parasitic reactions at the zinc anode side.These reactions include hydrogen evolution reaction,passivation,and dendrites,resulting in poor Coulombic efficiency and short lifespan of AZIBs.A comprehensive review of aqueous electrolytes chemistry,zinc chemistry,mechanism and chemistry of parasitic reactions,and their relationship is lacking.Moreover,the understanding of strategies for suppressing parasitic reactions from an electrochemical perspective is not profound enough.In this review,firstly,the chemistry of electrolytes,zinc anodes,and parasitic reactions and their relationship in AZIBs are deeply disclosed.Subsequently,the strategies for suppressing parasitic reactions from the perspective of enhancing the inherent thermodynamic stability of electrolytes and anodes,and lowering the dynamics of parasitic reactions at Zn/electrolyte interfaces are reviewed.Lastly,the perspectives on the future development direction of aqueous electrolytes,zinc anodes,and Zn/electrolyte interfaces are presented.

Seasonal increase in nest defense,but not egg rejection,in a cuckoo host

The interactions between avian brood parasites and their hosts provide an informative and easy-to-handle system for studying coevolution.Avian brood parasitism reduces the reproductive success of hosts,and thus,hosts have evolved anti-parasitic strategies,such as rejecting parasitic eggs and adopting aggressive nest defense strategies,to avoid the cost brought on by brood parasitism.To test whether host anti-parasitic strategies are adjusted with the risk of being parasitized when the breeding seasons of brood parasites and hosts are not synchronous,we conducted a field experiment assessing nest defense and egg recognition behaviors of the Isabelline Shrike(Lanius isabellinus),a host of the Common Cuckoo(Cuculus canorus).In the local area,the host Isabelline Shrike begins to breed in April,whereas the summer migratory Common Cuckoo migrates to the local area in May and begins to lay parasitic eggs.Results showed that nest defense behaviors of the Isabelline Shrike increases significantly after cuckoo arrival,showing higher aggressiveness to cuckoo dummies,with no significant difference in attack rates among cuckoo,sparrowhawk and dove dummies,but their egg rejection did not change significantly.These results imply that Isabelline Shrikes may adjust their nest defense behavior,but not egg rejection behavior,with seasonality.

Hepatolithiasis:Epidemiology,presentation,classification and management of a complex disease

The term hepatolithiasis describes the presence of biliary stones within the intrahepatic bile ducts,above the hilar confluence of the hepatic ducts.The disease is more prevalent in Asia,mainly owing to socioeconomic and dietary factors,as well as the prevalence of biliary parasites.In the last century,owing to migration,its global incidence has increased.The main pathophysiological mechanisms involve cholangitis,bile infection and biliary strictures,creating a self-sustaining cycle that perpetuates the disease,frequently characterised by recurrent episodes of bacterial infection referred to as syndrome of“recurrent pyogenic cholangitis”.Furthermore,long-standing hepatolithiasis is a known risk factor for development of intrahepatic cholangiocarcinoma.Various classifications have aimed at providing useful insight of clinically relevant aspects and guidance for treatment.The management of symptomatic patients and those with complications can be complex,and relies upon a multidisciplinary team of hepatologists,endoscopists,interventional radiologists and hepatobiliary surgeons,with the main goal being to offer relief from the clinical presentations and prevent the development of more serious complications.This comprehensive review provides insight on various aspects of hepatolithiasis,with a focus on epidemiology,new evidence on pathophysiology,most important clinical aspects,different classification systems and contemporary management.

Diversity of parasitic cuckoos and their hosts in China

In this exposé we provide the first review of host use by brood parasitic cuckoos in a multiple-cuckoo system in China, based on our own long-term field data and a compilation of observations obtained from the literature. In total, we found that 11 species of cuckoos utilized altogether 55 host species. These hosts belong to 15 families, in which Sylviidae, Turdidae and Timaliidae account for 22.6%, 20.8% and 17.0% of parasitism records, respectively. The Common Cuckoo (Cuculus canorus) had the widest range of host species, accounting for 45.5% of the total number of parasitized species (25 in 10 families) of all parasitism records and is the most frequent brood parasite in the country. Cuckoo species differed in their egg coloration and the extent of egg polymorphism with most of them, e.g. the Common Cuckoo, the Lesser Cuckoo (C. poliocephalus) and the Plaintive Cuckoo (Cacomantis merulinus) laying well mimetic eggs with respect to their hosts based on human being’s visual observations, while others such as the Large Hawk-cuckoo (C. sparverioides), the Himalayan Cuckoo (C. saturatus) and the Asian Emerald Cuckoo (Chrysococcyx maculatus) usually laid non-mimetic eggs. The use of cuckoo hosts and egg color variation in China are compared with those in other parts of their ranges in Asia.

Summer gregarine infection in Antarctic krill Euphausia superba in the Dumont D’Urville Sea,East Antarctic

Antarctic krill Euphausia superba plays a key role in the Antarctic food web.The trophic linkage between krill and other macro-organisms has been studied in the past decades,but the variability of parasites in krill is less studied and remains poorly understood.Therefore,it is important to understand the factors that influence abundance and infection of parasites in krill.Moreover,the relationship between the infection intensity of parasite and krill diet needs to be clarified,which is helpful for understanding the role of parasite in the food web.We investigated the abundance of the highly prevalent gregarine parasites in the digestive tract of krill and the factors influencing the gregarine infection to krill in the East Antarctic.The infection rate of Cephaloidophora pacifica Avdeev,1985 to krill(n=50 individuals)was 94%.The results of generalized linear model show the infection intensity of C.pacifica to the host was related significantly to the station,krill size,and maturity stage,but not the food species and abundance in the stomach of krill.Abundance of C.pacifica in krill differed among stations,and the lowest abundance occurred in the station nearest to the coast.Gregarines abundance varied among sexual maturity stages of krill and increased with krill size.

Common Cuckoo(Cuculus canorus)nestlings adapt their begging behavior to the host signal system

Common Cuckoos(Cuculus canorus)dependent on parental care for post-hatching demonstrate an intriguing ability to modify their begging vocalizations to ensure maximum care and resources from their interspecific foster parents.Here,we compared begging calls of the Common Cuckoo nestlings fed by four host species,the Grey Bushchat(Saxicola ferreus),Siberian Stonechat(Saxicola maurus),Daurian Redstart(Phoenicurus auroreus),and Oriental Magpie-robin(Copsychus saularis).Results showed that begging calls of the stonechat-,redstart-,and robin-cuckoo resemble those of host species'nestlings in various aspects like low frequency,high frequency,frequency bandwidth and peak frequency,while the bushchat-cuckoo chicks'begging calls were only comparable to their host species in terms of how long they lasted and their peak frequency.In addition,cuckoo nestlings raised in different host nests displayed significant variations in their begging calls in low and peak frequency.This study suggests that cuckoo nestlings do not mimic host species nestlings'begging calls throughout the nestling period,but may tune their begging calls according to host species,while begging calls vary with cuckoo and host species nestlings'ages.Future research should study the parents'reactions to these calls in different host species for a better understanding of the mechanisms underlying such adaptations.

Feeding ecology and interactions with mammal hosts in a symbiotic genus of birds(Buphagus spp.)in Namibia

As the sole obligate symbiotic birds in Africa,oxpeckers offer a unique model for studying symbiotic relationships.Due to the multitrophic level they occupy and the context dependent foraging behavior they exhibit,the type of symbiotic relationship can be variable.In addition to providing a cleaning service to the host by removing ticks,oxpeckers frequently feed on blood,mucus,and saliva,inflicting potential damage on the host.Here,we used DNA metabarcoding on faecal samples to analyze the taxonomic composition of the trophic interactions of the Yellow-billed Oxpecker(Buphagus africanus)and Red-billed Oxpecker(B.erythrorhynchus)in northeastern Namibia.In contrast to conventional methods,DNA metabarcoding allows for a detailed identification of dietary resources encompassing both mammal hosts and consumed arthropods within the same samples.With this information,we examined differences in the diet composition between oxpecker species and localities,as well as the co-occurrence between host and arthropod species.Our findings revealed that oxpeckers predominantly source their diet from mammals,ticks,and flies;however,ticks and flies rarely co-occur in the diet of an individual.We observed variability among individuals in their feeding ecology,which is strongly correlated with locality and,to a lesser extent,with the mammal host.We noted a high degree of mobility between hosts within relatively short periods,with 32%of the samples showing traces of at least two mammal hosts.This study illustrates the dynamic foraging behavior of these specialized symbiotic birds,shedding light on their potential role in pest control services and disease transmission.

Parasites of the liver:A global problem?

Parasitic liver diseases can be caused by trematodes,cestodes,nematodes,and protozoa.This pathology is significant because millions of people in different parts of the world have liver parasites,which can manifest themselves in the development of inflammation,liver cysts,cholecystitis,cholelithiasis,pancreatitis and liver cirrhosis that are often threatening their lives.The International Agency for Research on Cancer considers three species of trematodes,Schistosoma haematobium,Opisthorchis viverrini and Clonorchis sinensis,to be carcinogens.Complex modern examination methods,in some cases including extensive screening of large populations,are required for diagnosing liver parasites.Treatment of parasitic liver diseases is differentiated and can involve a combination of surgical and therapeutic measures.There is no doubt that the clinical and epidemiological scale allows one to regard parasitic liver diseases as a global healthcare problem.