Horizontal transmission maintains host specificity and codiversification of symbionts in a brood parasitic host.

In host-symbiont systems, interspecific transmissions create opportunities for host switches, potentially leading to cophylogenetic incongruence. In contrast, conspecific transmissions often result in high host specificity and congruent cophylogenies. In most bird-feather mite systems, conspecific transmission is considered dominant, while interspecific transmission is supposedly rare. However, while mites typically maintain high host specificity, incongruent cophylogenies are common. To explain this conundrum, we quantify the magnitude of conspecific vs. interspecific transmission in the brood parasitic shiny cowbird (Molothrus bonariensis). M. bonariensis lacks parental care, allowing the assessment of the role of horizontal transmission alone in maintaining host specificity. We found that despite frequent interspecific interactions via foster parental care, mite species dispersing via conspecific horizontal contacts are three times more likely to colonize M. bonariensis than mites transmitted vertically via foster parents. The results highlight the previously underappreciated rate of transmission via horizontal contacts in maintaining host specificity on a microevolutionary scale. On a macroevolutionary scale, however, host switches were estimated to have occurred as frequently as codivergences. This suggests that macroevolutionary patterns resulting from rare events cannot be easily generalized from short-term evolutionary trends.

Grain Structure Evolution in 6013 Aluminum Alloy during High Heat-Input Friction-Stir Welding.

This work was undertaken to evaluate the influence of friction-stir welding (FSW) under a high-heat input condition on microstructural evolution. Given the extreme combination of deformation conditions associated with such an FSW regime (including the highest strain, temperature, and strain rate), it was expected to result in an unusual structural response. For this investigation, a commercial 6013 aluminum alloy was used as a program material, and FSW was conducted at a relatively high spindle rate of 1100 rpm and an extremely low feed rate of 13 mm/min; moreover, a Ti-6Al-4V backing plate was employed to reduce heat loss during welding. It was found that the high-heat-input FSW resulted in the formation of a pronounced fine-grained layer at the upper weld surface. This observation was attributed to the stirring action exerted by the shoulder of the FSW tool. Another important issue was the retardation of continuous recrystallization. This interesting phenomenon was explained in terms of a competition between recrystallization and recovery at high temperatures. Specifically, the activation of recovery should reduce dislocation density and thus retard the development of deformation-induced boundaries.

On the Degree of Plastic Strain during Laser Shock Peening of Ti-6Al-4V.

Laser shock peening (LSP) is an innovative technique that is used to enhance the fatigue strength of structural materials via the generation of significant residual stress. The present work was undertaken to evaluate the degree of plastic strain introduced during LSP and thus improve the fundamental understanding of the LSP process. To this end, electron backscatter diffraction (EBSD) and nano-hardness measurements were performed to examine the microstructural response of laser-shock-peened Ti-6Al-4V alloy. Only minor changes in both the shape of α grains/particles and hardness were found. Accordingly, it was concluded that the laser-shock-peened material only experienced a small plastic strain. This surprising result was attributed to a relatively high rate of strain hardening of Ti-6Al-4V during LSP.

External and gastrointestinal parasites of the black-faced ibis Theristicus melanopis (Pelecaniformes: Threskiornithidae) in the Los Ríos region, southern Chile.

The black-faced ibis, Theristicus melanopis, is considered a useful bird species for agricultural activity because it preys upon various invertebrate and vertebrate pests. Although it is a common species in Chile, limited information is available regarding its parasites. The main objective of this study was to recover the diversity of ectoparasites and gastrointestinal helminths in black-faced ibises living in the communes of Valdivia and Panguipulli, Los Ríos region. A total of 74 specimens were received for examination from the Centro de Rehabilitación de Fauna Silvestre at the Universidad Austral de Chile (CEREFAS-UACh), Valdivia, in 2011-2015. Black-faced ibises were externally inspected for ectoparasites by direct examining of the plumage, and necropsies were performed to examine digestive and respiratory organs in search of endoparasites. For each taxon, prevalence, mean intensity, mean abundance, and range of parasites per bird were estimated. Five species of ectoparasites and six species of helminths were identified. A total of 298 lice (Insecta: Phthiraptera) belonging to four species were collected: Ardeicola melanopis (13.51%), Colpocephalum trispinum (20.27%), Ibidoecus fissisignatus (4.05%), and Plegadiphilus mamillatus (9.46%). In addition, one feather mite species, Diodochaetus melanopis (Acari: Pterolichoidea) (17.56%), was isolated. In 48 black-faced ibis (64.86%), a total of 1229 gastrointestinal helminths were found: two nematodes, Porrocaecum heteropterum (55.41%) and Baruscapillaria obsignata (24.32%); one tapeworm Eugonodaeum nasuta (20.27%); two digeneans, Echinoparyphium recurvatum (1.35%) and Strigea bulbosa (6.76%); and the acanthocephalan Sphaerirostris sp. (1.35%). The findings of the following parasites present new host-parasite associations: P. mamillatus, D. melanopis, B. obsignata, E. recurvatum, S. bulbosa, and Sphaerirostris sp. Additionally, the louse P. mamillatus, feather mite D. melanopis, platyhelminths E. nasuta, E. recurvatum and S. bulbosa, and the acanthocephalan Sphaerirostris sp. are new records for the fauna of Chile.

Microstructural Aspects of the Fabrication of Al/Al2O3 Composite by Friction Stir Processing.

The purpose of this work was the examination of microstructural evolution during the fabrication of an Al/Al2O3 composite by friction stir processing (FSP). In order to obtain new insight into this process, a longitudinal section of the produced composite was studied, and advanced characterization techniques (including electron backscatter diffraction and microhardness mapping) were applied. It was found that the reinforcing particles rapidly rearranged into the "onion-ring" structure, which was very stable against the subsequent dispersion. Specifically, the remnants of the comparatively coarse-scale particle agglomerations have survived even after 12 FSP passes. Therefore, it was concluded that three or four FSP passes, which are often applied in practice, are not sufficient to provide a homogeneous dispersion of the reinforcing particles. It was also revealed that the gradual distribution of the nanoscale Al2O3 particles throughout the aluminum matrix promoted a subtle reduction in both the portion of high-angle boundaries and the average grain size. These observations were attributed to the particle pinning of grain-boundary migration and dislocation slip.

Diversity and structure of feather mite communities on seabirds from the north-east Atlantic and Mediterranean Sea.

The richness and structure of symbiont assemblages are shaped by many factors acting at different spatial and temporal scales. Among them, host phylogeny and geographic distance play essential roles. To explore drivers of richness and structure of symbiont assemblages, feather mites and seabirds are an attractive model due to their peculiar traits. Feather mites are permanent ectosymbionts and considered highly host-specific with limited dispersal abilities. Seabirds harbour species-rich feather mite communities and their colonial breeding provides opportunities for symbionts to exploit several host species. To unravel the richness and test the influence of host phylogeny and geographic distance on mite communities, we collected feather mites from 11 seabird species breeding across the Atlantic Ocean and Mediterranean Sea. Using morphological criteria, we identified 33 mite species, of which 17 were new or recently described species. Based on community similarity analyses, mite communities were clearly structured by host genera, while the effect of geography within host genera or species was weak and sometimes negligible. We found a weak but significant effect of geographic distance on similarity patterns in mite communities for Cory's shearwaters Calonectris borealis. Feather mite specificity mainly occurred at the host-genus rather than at host-species level, suggesting that previously inferred host species-specificity may have resulted from poorly sampling closely related host species. Overall, our results show that host phylogeny plays a greater role than geography in determining the composition and structure of mite assemblages and pinpoints the importance of sampling mites from closely-related host species before describing mite specificity patterns.

Effect of Tempforming on Strength and Toughness of Medium-Carbon Low-Alloy Steel.

The effect of tempforming on the strength and fracture toughness of 0.4%C-2%Si-1%Cr-1%Mo-VNb steel was examined. Plate rolling followed by tempering at the same temperature of 600 °C increases yield stress by 25% and the Charpy V-notch impact energy by a factor of ~10. Increasing rolling reduction leads to the reorientation and elongation of grains toward the rolling direction (RD) and the development of a strong {001} <110> (rotated cube) texture component that highly enhances fracture toughness. A lamellar structure with a spacing of 72 nm between boundaries and a lattice dislocation density of ~1015 m-2 evolves after tempforming at 600 °C with a total strain of 1.4. Two types of delamination were found, attributed to crack branching and the propagation of secondary cracks along the rolling plane perpendicular to the propagation direction of the primary crack. Delamination toughness is associated with the nucleation of secondary cracks in RD and their propagation over a large distance. The critical condition for delamination toughness is the propagation of primary cracks by the ductile fracture mechanism and the propagation of secondary cracks by the brittle quasi-cleavage mechanism.

Small-scale fluctuations of laser beam fluence at the large B-integral in ultra-high intensity lasers.

Analytical expressions for the spatial spectrum of fluence fluctuations of a laser pulse propagating in a medium with Kerr nonlinearity have been obtained. It is shown that inhomogeneities with a spatial scale much larger than the critical scale of self-focusing grow insignificantly even at large values of the B-integral. Experiments using BK7 glass and a KDP crystal as a nonlinear medium confirm the obtained theoretical results. This may be interesting for pulse post-compression, frequency doubling, and other experiments using transmission optical elements in ultra-high intensity lasers.

New feather mites of the genus Neodectes (Acariformes: Proctophyllodidae) from honeyeaters (Passeriformes: Meliphagidae) in Australia.

Five new species of the genus Neodectes Park and Atyeo, 1971 (Proctophyllodidae: Pterodectinae) are described from honeyeaters (Passeriformes: Meliphagidae) in Australia: Neodectes cissomelae sp. n. from Cissomela pectoralis (Gould) (type host) and Melithreptus gularis laetior Gould; N. hallidayi sp. n. from Anthochaera carunculata (Shaw) (type host) and A. chrysoptera (Latham); N. manorinae sp. n. from Manorina melanocephala (Latham); N. ophioglossus sp. n. from Conopophila rufogularis (Gould) (type host) and Lichmera indistincta (Vigors and Horsfield); and N. walteri sp. n. from Anthochaera phrygia (Shaw). A key to species and a world checklist to Neodectes species are provided for the first time. A new combination, Neodectes dicranochaetus (Gaud, 1968) comb. n., is proposed for Proterothrix dicranochaeta Gaud, 1968, which is transferred herein to the genus Neodectes from Proterothrix Gaud, 1968 (Proctophyllodidae).

Dissimilar Friction Stir Welding of AA2519 and AA5182.

In this study, the friction-stir welding (FSW) technique was successfully applied for joining of AA2519 to AA5181 alloy. Microstructure and mechanical properties of dissimilar FSW joints were investigated by optical microscopy, microhardness, and tensile testing. The deformation behaviour of the welded joints was elucidated via the digital image correlation technique. After welding, the ultimate tensile strength of joints was ~300 MPa and ductility was ~16%. The microhardness values observed at the stir zone were higher than those in the base material AA5182. The produced welds demonstrate nearly 100% (based on AA5182) joint efficiency.

Tailoring of Dissimilar Friction Stir Lap Welding of Aluminum and Titanium.

An approach was proposed to optimize dissimilar friction stir lap welding of aluminum and titanium alloys. The basic concept of the new technique included (i) the plunging of the welding tool solely into the aluminum part (i.e., no direct contact with the titanium side) and (ii) the welding at a relatively high-heat input condition. It was shown that sound welds could be readily produced using an ordinary cost-effective tool, with no tool abrasion and no dispersion of harmful titanium fragments within the aluminum side. Moreover, the intermetallic layer was found to be as narrow as ~0.1 µm, thus giving rise to excellent bond strength between aluminum and titanium. On the other hand, several important shortcomings were also revealed. First of all, the high-heat input condition provided significant microstructural changes in the aluminum part, thereby resulting in essential material softening. Furthermore, the new approach was not feasible in the case of highly alloyed aluminum alloys due to the relatively low rate of self-diffusion in these materials. An essential issue was also a comparatively narrow processing window.

Improving focusability of post-compressed PW laser pulses using a deformable mirror.

The use of the post-compression technique ensures gain in laser pulse peak power but at the same time degrades beam focusability due to the nonlinear wavefront distortions caused by a spatially nonuniform beam profile. In this paper a substantial focusability improvement of a post-compressed laser pulse by means of adaptive optics was demonstrated experimentally. The Strehl ratio increase from 0.16 to 0.43 was measured. Simulations showed that the peak intensity in this case reaches 0.52 of the theoretical limit.

Helminth and ectoparasitic faunas of the Harris's hawk, Parabuteo unicinctus (Accipitriformes: Accipitridae), in Chile: new data on host-parasite associations for Neotropical raptors.

Birds of prey harbor a wide spectrum of various parasites, mostly with a heteroxenous life cycle. However, most reports on their parasites come from Europe. Although the Harris's hawk (Parabuteo unicinctus) is a widespread species in America, parasitological surveys on this hawk are mostly focused on coprological findings and ectoparasites, with poor attention paid to helminths. The aim of this study was to gather new and additional data on host-parasite associations for the Harris's hawk. Twenty-nine birds from central and southern Chile were necropsied. Further, nine birds from a rehabilitation center and 22 museum specimens were inspected for ectoparasites. Sixty-eight percent of birds hosted at least one parasite species. Four lice species, one mite species and eight helminth species (five nematodes, two platyhelminthes and one acanthocephalan) were recorded. Parasitic lice Colpocephalum nanum and Nosopon chanabense, and a nematode Cyathostoma (Hovorkonema) americana were recorded for the first time in raptors from the Neotropics. A feather mite, Pseudalloptinus sp., nematodes, Physaloptera alata and Microtetrameres sp., and a trematode Neodiplostomim travassosi, were recorded for the first time in Chile. The presence of diverse heteroxenous helminths reported here in the Harris's hawk could be explained by the generalist diet of this raptor.

Two new species of feather mites (Acariformes, Astigmata) from the black-tailed godwit, Limosalimosa (Charadriiformes, Scolopacidae), in Korea.

Two new species of feather mites are described from two individuals of the black-tailed godwit, Limosalimosa (Linnaeus, 1758), in Korea: Alloptes (Conuralloptes) neolimosaesp. nov. (Analgoidea, Alloptidae) and Phyllochaetalimosae sp. nov. (Pterolichoidea, Syringobiidae). Males of A. (C.) neolimosaesp. nov. are distinguished from A. (C.) limosae in having the hysteronotal shield with a straight anterior margin, setae h2 enlarged and slightly flattened in the basal half, and the terminal lamella monotonously transparent without sclerotized patches; females differ in having legs IV with ambulacral discs extending to or slightly beyond the level of setae f2. The discovery of P.limosae sp. nov. represents the first record of the feather mite genus Phyllochaeta on godwits of the genus Limosa Brisson, 1760 (Scolopacidae, Limosinae). Males of P.limosae sp. nov. are distinguished from P.secunda in having the terminal cleft semi-ovoid with a length-to-width ratio of 1.7, and the terminal membranes with 15 or 16 finger-shaped denticles; females differ in having the hysteronotal shield bearing faint longitudinal striations in the posterior third and lacking lacunae, and setae c1 situated posterior to the level of setae c2. Additionally, we obtained partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene from A. (C.) neolimosaesp. nov. and estimated genetic distances from 10 other Alloptes species based on comparisons of COI sequences.

Compact pulse shaper based on a tilted volume Bragg grating.

A compact optical layout of a pulse shaper for strongly chirped laser pulses of nanosecond time scale exploiting a tilted chirped volume Bragg grating and a programmable spatial light modulator is proposed. The setup has a non-zero frequency dispersion; thus it may be used for stretching or compressing the pulse and controlling its shape simultaneously. The feasibility of spectral shaping with a resolution of 0.16 nm, corresponding to a time resolution of 150 ps, and a contrast ratio of 102 is demonstrated experimentally.

Ectoparasites of Columbina passerina insularis (Columbiformes) in the National Zoological Park, Havana, Cuba.

Ectoparasites of 18 free-living Cuban Ground Doves, Columbina passerina insularis (Columbiformes: Columbidae), captured in the National Zoological Park, Havana, Cuba, were identified. The collected ectoparasites included two species of lice (Phthiraptera: Ischnocera): Columbicola passerinae (77.1%), and Physconelloides eurysema (50%), as well as four species of feather mites (Astigmata: Falculiferidae): Pterophagus lomatus (83.3%), Byersalges talpacoti (50%), Byersalges phyllophorus (72.2%), and Hyperaspidacarus tridentatus (27.7%). Pterophagus lomatus, B. phyllophorus, and H. tridentatus represent new records for Cuba.

Directional couplings between the respiration and parasympathetic control of the heart rate during sleep and wakefulness in healthy subjects at different ages.

Cardiorespiratory interactions are important, both for understanding the fundamental processes of functioning of the human body and for development of methods for diagnostics of various pathologies. The properties of cardiorespiratory interaction are determined by the processes of autonomic control of blood circulation, which are modulated by the higher nervous activity. We study the directional couplings between the respiration and the process of parasympathetic control of the heart rate in the awake state and different stages of sleep in 96 healthy subjects from different age groups. The detection of directional couplings is carried out using the method of phase dynamics modeling applied to experimental RR-intervals and the signal of respiration. We reveal the presence of bidirectional couplings between the studied processes in all age groups. Our results show that the coupling from respiration to the process of parasympathetic control of the heart rate is stronger than the coupling in the opposite direction. The difference in the strength of bidirectional couplings between the considered processes is most pronounced in deep sleep.

Ectoparasites of Columbina passerina insularis (Columbiformes) in the National Zoological Park, Havana, Cuba / Ectoparasitas de Columbina passerina insularis (Columbiformes) no Parque Zoológico Nacional, Havana, Cuba

Abstract Ectoparasites of 18 free-living Cuban Ground Doves, Columbina passerina insularis (Columbiformes: Columbidae), captured in the National Zoological Park, Havana, Cuba, were identified. The collected ectoparasites included two species of lice (Phthiraptera: Ischnocera): Columbicola passerinae (77.1%), and Physconelloides eurysema (50%), as well as four species of feather mites (Astigmata: Falculiferidae): Pterophagus lomatus (83.3%), Byersalges talpacoti (50%), Byersalges phyllophorus (72.2%), and Hyperaspidacarus tridentatus (27.7%). Pterophagus lomatus, B. phyllophorus, and H. tridentatus represent new records for Cuba.

Resumo Foram identificados os ectoparasitas de 18 rolinhas-cinzentas de vida livre, Columbina passerina insularis (Columbiformes: Columbidae), capturadas no Parque Zoológico Nacional de Havana, Cuba. Os ectoparasitas coletados pertencem à duas espécies de piolhos (Phthiraptera: Ischnocera): Columbicola passerinae (77,1%) e Physconelloides eurysema (50%), bem como à quatro espé cies de ácaros de pena (Astigmata: Falculiferidae): Pterophagus lomatus (83,3%), Byersalges talpacoti (50%), Byersalges phyllophorus (72,2%) e Hyperaspidacarus tridentatus (27,7%). Pterophagus lomatus, B. phyllophorus e H. tridentatus representam novos registros para Cuba.

Helminth and ectoparasitic faunas of the Harris's hawk, Parabuteo unicinctus (Accipitriformes: Accipitridae), in Chile: new data on host-parasite associations for Neotropical raptors / Helmintos e ectoparasitas do gavião-asa-de-telha (Accipitriformes: Parabuteo unicinctus) no Chile: novas associações parasita-hospedeiro para os rapinantes neotropicais

Abstract Birds of prey harbor a wide spectrum of various parasites, mostly with a heteroxenous life cycle. However, most reports on their parasites come from Europe. Although the Harris's hawk (Parabuteo unicinctus) is a widespread species in America, parasitological surveys on this hawk are mostly focused on coprological findings and ectoparasites, with poor attention paid to helminths. The aim of this study was to gather new and additional data on host-parasite associations for the Harris's hawk. Twenty-nine birds from central and southern Chile were necropsied. Further, nine birds from a rehabilitation center and 22 museum specimens were inspected for ectoparasites. Sixty-eight percent of birds hosted at least one parasite species. Four lice species, one mite species and eight helminth species (five nematodes, two platyhelminthes and one acanthocephalan) were recorded. Parasitic lice Colpocephalum nanum and Nosopon chanabense, and a nematode Cyathostoma (Hovorkonema) americana were recorded for the first time in raptors from the Neotropics. A feather mite, Pseudalloptinus sp., nematodes, Physaloptera alata and Microtetrameres sp., and a trematode Neodiplostomim travassosi, were recorded for the first time in Chile. The presence of diverse heteroxenous helminths reported here in the Harris's hawk could be explained by the generalist diet of this raptor.

Resumo As aves de rapina representam uma fonte importante de parasitas heteroxenos. Porém, a maioria dos relatos são da Europa. O gavião-asa-de-telha (Parabuteo unicinctus) é uma espécie amplamente distribuída no continente Americano, porém estudos parasitológicos nessas aves têm documentado achados coprológicos e ectoparasitas, com poucos relatos sobre endoparasitas como helmintos. Por essa razão, o objetivo deste estudo foi descrever novas associações parasita-hospedeiro para o gavião-asa-de-telha e rapinantes neotropicais. Vinte nove aves provenientes do centro e sul do Chile foram submetidas à necropsia. Por outro lado, nove aves de um centro de reabilitação e 22 espécimes de museu foram inspecionados em busca de ectoparasitas. Do total de aves, 68,3% foram identificadas como portadoras de pelo menos uma espécie de parasita. Quatro espécies de piolhos, um ácaro e oito helmintos (cinco nematoides, dois platelmintos e um acantocéfalo) foram registrados. Os piolhos Colpocephalum nanum, Nosopon chanabense e o nematóide Cyathostoma (Hovorkonema) americana são reportados pela primeira vez em rapinantes neotropicais. Colpocephalum nanum, N. chanabense, Pseudalloptinus sp., Physaloptera alata, Microtetrameres sp., C. (H.) americana e Neodiplostomim travassosi, são reportados pela primeira vez no Chile. A diversidade de helmintos heteróxenos, identificados neste trabalho, poderia ser explicada devido à dieta geralista do gavião-asa-de-telha.

Panoramic Endocardial Optical Mapping Demonstrates Serial Rotors Acceleration and Increasing Complexity of Activity During Onset of Cholinergic Atrial Fibrillation.

Background Activation during onset of atrial fibrillation is poorly understood. We aimed at developing a panoramic optical mapping system for the atria and test the hypothesis that sequential rotors underlie acceleration of atrial fibrillation during onset. Methods and Results Five sheep hearts were Langendorff perfused in the presence of 0.25 µmol/L carbachol. Novel optical system recorded activations simultaneously from the entire left and right atrial endocardial surfaces. Twenty sustained (>40 s) atrial fibrillation episodes were induced by a train and premature stimuli protocol. Movies obtained immediately (Initiation stage) and 30 s (Early Stabilization stage) after premature stimulus were analyzed. Serial rotor formation was observed in all sustained inductions and none in nonsustained inductions. In sustained episodes maximal dominant frequency increased from (mean±SD) 11.5±1.74 Hz during Initiation to 14.79±1.30 Hz at Early Stabilization (P<0.0001) and stabilized thereafter. At rotor sites, mean cycle length (CL) during 10 prerotor activations increased every cycle by 0.53% (P=0.0303) during Initiation and 0.34% (P=0.0003) during Early Stabilization. In contrast, CLs at rotor sites showed abrupt decreases after the rotors appearances by a mean of 9.65% (P<0.0001) during both stages. At Initiation, atria-wide accelerations and decelerations during rotors showed a net acceleration result whereby post-rotors atria-wide minimal CL (CLmin) were 95.5±6.8% of the prerotor CLmin (P=0.0042). In contrast, during Early Stabilization, there was no net acceleration in CLmin during accelerating rotors (prerotor=84.9±11.0% versus postrotor=85.8±10.8% of Initiation, P=0.4029). Levels of rotor drift distance and velocity correlated with atria-wide acceleration. Nonrotor phase singularity points did not accelerate atria-wide activation but multiplied during Initiation until Early Stabilization. Increasing number of singularity points, indicating increased complexity, correlated with atria-wide CLmin reduction (P<0.0001). Conclusions Novel panoramic optical mapping of the atria demonstrates shortening CL at rotor sites during cholinergic atrial fibrillation onset. Atrial fibrillation acceleration toward Early Stabilization correlates with the net result of atria-wide accelerations during drifting rotors activity.