Sound production in the Ponto-Caspian goby (Neogobius fluviatilis (Pallas, 1814)) and its acoustic affinity with mediterranean species

Cilj provedenog istraživanja bio je opisati vokalni repertoar ponto-kaspijskog riječnog glavočića (Neogobius fluviatilis) te usporediti njegova akustična svojstva s vokalnim mediteranskim vrstama iz Gobius grupe. Produkcija zvuka bila je inducirana ―testom uljeza. Istražili smo 5 akustičnih svojstva za 13 jedinki. Vokalni repertoar riječnog glavočića sastoji se od niza kratkih zvukova produciranih tijekom agresivnih i reproduktivnih interakcija. Zvukovi se sastoje od rapidno ponovljenih pulseva, tipičnog tonalnog karaktera. Zvukovi traju oko 200 ms uz prosječnu vrijednost frekvencije od oko 80 Hz. Struktura zvuka se nije mijenjala s obzirom na etološki kontekst, što potvrđuje njen stereotipski karakter. Podaci o akustičnim svojstvima riječnog glavočića zajedno sa podacima mediteranskih vrsta, analizirani su pomoću Faktorijalne diskriminantne funkcijske analize (DFA) kako bi procijenili u kojoj se mjeri vrste mogu razlikovati s obzirom na njihova akustična svojstava. Rezultati pokazuju kako je stopa ponavljanja pulseva najvažnije svojstvo za razlikovanje vrsta. Smatramo kako upravo ta karakteristika zvuka sadrži informacije o samoj vrsti zbog čega je ključna pri određivanju filogenetskih odnosa. Naše istraživanje pokazuje, sukladno molekularnim filogenetskim analizama, da se vrste koje produciraju tonalne zvukove grupiraju zajedno. Rezultati provedenog istraživanja interpretirani su sukladno geološkim i filogentskim događajima za koje se vjeruje da su potaknuli specijaciju europskih glavoča.The aim of this study was to describe the vocal repertoire of the Ponto-Caspian goby (Neogobius fluviatilis) and to compare its acoustic properties with those of the other soniferous Mediterranean gobies belonging to the ―Gobius‖ lineage. Sound emission was elicited by means of ―intruder tests‖. 5 acoustic properties were measured from 13 individuals. The vocal repertoire of the species consisted of sequences of short vocalizations (average 200 ms) showing an average fundamental frequency of about 80 Hz during both agonistic and reproductive intraspecific interactions. Sound properties did not differ between reproductive and the aggressive contexts, and the general structure of sounds were highly stereotyped. Discriminant Function Analysis was performed with individual means of five acoustic properties for seven species to assess how well species could be differentiated on the basis of acoustics, and their degree of affinities. The results suggested that the pulse repetition rate of the sounds was the most important property in differentiating the species. The species producing tonal sounds clustered together in line with the results of recent molecular phylogenic studies. The results were discussed in light of the geological and phylogeographic events believed to have driven the diversification of European gobies

The Extended Chiral Quark Model in a Tamm-Dancoff Inspired Approximation

A procedure inspired by the Tamm-Dancoff method is applied to the chiral quark model which has been extended to include additional degrees of freedom: a pseudoscalar isoscalar field as well as a triplet of scalar isovector fields. The simpler, generic $\sigma$ -- model has been used before as a test for the Tamm-Dancoff inspired approximation (TDIA). The extended chirial quark model is employed here to investigate possible novel effects of the additional degrees of freedom as well as to point out the necessesity to introduce a SU(3) flavour. Model predictions for the axial-vector coupling constant and for the nucleon magnetic moment obtained in TDIA are compared with experimental values.Comment: 14 pages, LaTe

Temperaturna ovisnost udarnog presjeka σ5S za proces energijskog združivanja Na(3P) + Na(3P) → Na(5S) + Na(3S)

Applying the method of laser induced fluorescence, the cross section σ5S for the energy pooling process Na(3P) + Na(3P) → Na(5S) + Na(3S) has been determined at temperatures in the interval from 567 to 676 K. It has been found that σ5S decreases with increasing temperature, exhibiting σ5S ∝ T −1.3 dependence. The results show excellent agreement with the recent theoretical calculations. Also, the determined temperature dependence of the cross section σ5S fits very well into recently reported general σ vs. T scheme for the exothermic collisional excitation energy transfer cross sections, which includes various collision partners and various types of collisional excitation energy transfer processes with different energy defects.Primjenom metode laserski inducirane fluorescencije određen je udarni presjek σ5S za proces združivanja energije (engl. energy pooling process) Na(3P) + Na(3P) → Na(5S) + Na(3S) u temperaturnom području od 567 to 676 K. Ustanovljeno je da se vrijednosti za σ5S smanjuju s porastom temperature, pri čemu se pokazuje ovisnost σ5S ∝ T −1.3 . Dobiveni rezultati se izvrsno slažu s najnovijim teorijskim računima. Također, pokazano je da se mjerena temperaturna ovisnost udarnog presjeka σ5S vrlo dobro uklapa u opću sliku ovisnosti između σ i T, što je bila nedavno objavljena, a uključuje različite sudarne partnere i različite vrste sudarnih prijenosa energije pobude s različitim energijskim defektima

Nuclear Magnetic Resonance in High Magnetic Field: Application to Condensed Matter Physics

In this review, we describe the potentialities offered by the nuclear magnetic resonance (NMR) technique to explore at a microscopic level new quantum states of condensed matter induced by high magnetic fields. We focus on experiments realised in resistive (up to 34~T) or hybrid (up to 45~T) magnets, which open a large access to these quantum phase transitions. After an introduction on NMR observable, we consider several topics: quantum spin systems (spin-Peierls transition, spin ladders, spin nematic phases, magnetisation plateaus and Bose-Einstein condensation of triplet excitations), the field-induced charge density wave (CDW) in high $T_c$~superconductors, and exotic superconductivity including the Fulde-Ferrel-Larkin-Ovchinnikov superconducting state and the field-induced superconductivity due to the Jaccarino-Peter mechanism.Comment: 19 pages, 6 figure

Prijenos energije pobude između 6s5d 1D2 i 6s5d 3DJ stanja barija u sudarima s atomima helija, argona i ksenona

The cross sections for the Ba 6s5d 1D2 → 6s5d 3DJ excitation energy transfer, induced by collisions with He, Ar and Xe, were measured using laser absorption and fluorescence methods in the steady-state regime. The populations of the barium metastable 6s5d 1D2 and Ba 6s5d 3DJ states were created by subsequent radiative and collisional relaxation of the optically excited 6s6p 3P01 level. The four-level model, comprising 6s2 1S0, 6s6p 3P10, 6s5d 1D2 and 6s5d 3DJ states, is proposed for the description of the population and depopulation processes of the Ba metastable states in noble gas atmosphere. The analysis of the experimental results, within the assumed model, yields the following cross-section values for the investigated processes: σHe = 1.5×10-20 m2, σAr = 2×10-22 m2 and σXe = 8×10-21 m2, with an accuracy of ±50%.Metodom laserske apsorpcije i fluorescencije određeni su udarni presjeci za prijenos energije pobude u procesu Ba 6s5d 1D2 → 6s5d 3DJ uzrokovanom sudarima s atomima helija, argona i ksenona. Metastabilni nivoi 6s5d 1D2 i 6s5d 3DJ napučivani su radijativnom i sudarnom relaksacijom optički pobuđenog 6s6p 3P 0 1 stanja. U okviru predloženog modela sa četiri nivoa, koji uključuje 6s2 1S0, 6s6p 3P 0 1 , 6s5d 1D2 i 6s5d 3DJ stanja, opisani su procesi napučivanja i pražnjenja barijevih metastabila u atmosferi plemenitog plina. Analiza eksperimentalnih rezultata daje slijedeće udarne presjeke za istraživane procese: σHe = 1.5 × 10−20 m2 , σAr = 2 × 10−22 m2 σXe = 8 × 10−21 m2 , s točnošću od ±50