Host alarm calls attract the unwanted attention of the brood parasitic common cuckoo

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Call rate in Common Cuckoos does not predict body size and responses to conspecific playbacks

The brood parasitic Common Cuckoo Cuculus canorus is best known for its two-note “cu-coo” call which is almost continuously uttered by male during the breeding season and can be heard across long distances in the feld. Although the informative value of the cuckoo call was intensively investigated recently, it is still not clear whether call characteristic(s) indicate any of the phenotypic traits of the respective vocalising individuals. To fll this gap, we studied whether the call rate of male cuckoos (i.e., the number of calls uttered per unit of time) provides information on their body size, which might be a relevant trait during intrasexual territorial conficts. We captured free-living male cuckoos and measured their body size parameters (mass, wing, tail and tarsus lengths). Each subject was then radio-tagged, released, and its individual “cu-coo” calls were recorded soon after that in the feld. The results showed that none of the body size parameters covaried statistically with the call rates of individual male Common Cuckoos. In addition, we experimentally tested whether the “cu-coo” call rates afect behavioural responses of cuckoos using playbacks of either a quicker or a slower paced call than the calls with natural rates. Cuckoos responded similarly to both types of experimental playback treatments by approaching the speaker with statistically similar levels of responses as when presented with calls at the natural rate. We conclude that male Common Cuckoos do not advertise reliable information acoustically regarding their body size, and so, cuckoo calls are neither useful to characterize cuckoos’ phenotypic traits directly nor to indicate environmental quality indirectl

Nagy üvegképző hajlamú és nagy entrópiájú ötvözetek képződése és stabilitása

Két ötvözetcsalád, a tömbi formában előállított amorf (BMG) és a nagy entrópiájú (HEA) ötvözetek képződési mechanizmusát és stabilitását hasonlítjuk össze jelen közleményben. Az összehasonlítás fő elve az olvadékaik túlhűlési képessége a megszilárdulás folyamatában. A BMG-ötvözetek olvadékai a különböző típusú kémiai kötések miatt nagy túlhűlési hajlamot, s ebből eredően nagy üvegképző hajlamot is mutatnak. Ennek jellemző mechanizmusa a klaszterképződés, amellyel az atommozgékonyság s így a kristálycsíra-képződés is visszaszorul. A HEA-ötvözetek olvadékai nem mutatnak ilyen hajlamot. Nagy hőmérsékleten, közvetlenül az olvadáspont környékén, az olvadékfázissal azonos összetételű, rendezetlen szilárd oldat formájában kristályosodnak. A kétféle olvadéktípusban az eltérő atomi mobilitás tükröződik az olvadékok viszkozitásának eltérő hőmérséklet-függésében is. A HEA-ötvözeteknek a konfigurációs entrópia által dominált fázisstabilitásához elektronszerkezeti tényezők is hozzájárulnak: itt szerepet kap a d-elektronok részvétele az atomok közötti kötésekben

The Formation and Stability of Bulk Amorphous and High Entropy Alloys

Two kinds of phase stabilization mechanism are discussed and compared: the first is characteristic of the formation of bulk amorphous alloys, in which the high supercooling ability of multicomponent liquids is responsible for the glassy phase stabilization. Here the hindered nucleation of crystalline phases is the center phenomenon. The origin of this hindering is the slowing atomic mobility in the supercooling melt. In contrast the melt supercooling is negligible during the high entropy alloy formation. It is believed that stability of the crystalline single fcc phase is the consequence of the characteristic of high configurational entropy at high temperatures. However, the significance of this entropy-dominated stabilization is overestimated in several references. It has been concluded that transition metal contraction (arising from the d electron participation in the overall bonding state) does also contribute to the high temperature stability of fcc single phase in the high entropy alloys