Reproductive System Structure, Development and Function in Cephalopods with a New General Scale for Maturity Stages

The main types of reproductive system structure, development and functions in cephalopods are described from personal observations and use of the literature. There is one type in males and three in females which are order specific. These have provided a basis for examining possible evolutionary trends in reproductive system development and in reproductive strategies within coleoid cephalopods and for developing a general scale for maturity staging for males and females. Development of the cephalopod reproductive system consists of two main phases. The first includes sexual cell differentiation, growth and maturation (i.e. juvenile phase and physiological maturation). The second begins after maturation of sexual cells. It includes their transport and accumulation in different parts of the reproductive system and their conversion into spermatophores in males and eggs with protective coverings in females (i.e. physiological maturity, functional maturation and maturity). It was found that species with different life styles within each order have similar reproductive systems. This may be attributable to the relative youth in an evolutionary sense of the main groups of living cephalopods. A general scale of seven maturity stages for cephalopods was developed. Distinct characteristics of each stage are described and supplemented with a generalized drawing of gonad structure. In the first phase of reproductive system development, maturity stages are distinguished by the degree of development of the gonad and accessory glands. In the second phase maturity stages are distinguished by the fate of the mature sexual cells, particularly by their transport and location in different parts of the reproductive system up to the time of spawnin

Ultranarrow resonance peaks in the transmission and reflection spectra of a photonic crystal cavity with Raman gain

The Raman gain of a probe light in a three-state $\Lambda$-scheme placed into a defect of a one-dimensional photonic crystal is studied theoretically. We show that there exists a pump intensity range, where the transmission and reflection spectra of the probe field exhibit \textit{simultaneously} occurring narrow peaks (resonances) whose position is determined by the Raman resonance. Transmission and reflection coefficients can be larger than unity at pump intensities of order tens of $\mu$W/cm$^{2}$. When the pump intensity is outside this region, the peak in the transmission spectrum turns into a narrow dip. The nature of narrow resonances is attributed to a drastic dispersion of the nonlinear refractive index in the vicinity of the Raman transition, which leads to a significant reduction of the group velocity of the probe wave.Comment: 9 pages, 3 figure

Distribution, stock structure, and growth of the squid Berryteuthis magister (Berry, 1913) (Cephalopoda, Gonatidae) during summer and fall in the western Bering Sea

Distribution, abundance, and length-frequency composition of schoolmaster gonate squid, Berryteuthis magister, were studied during seven trawl surveys in the western Bering Sea between June and November 1993. Statolith age analysis was undertaken for 1,381 B. magister to estimate age, stock structure, and both growth and maturation rates. Three kinds of growth increments were revealed in B. magister statoliths. Daily periodicity of the second-order increments was confirmed by two independent, indirect methods. According to our data, B. magister live >1 yr; the oldest specimen was about 16 months old. Berryteuthis magister is a slow-growing and slow-maturing squid, and males exhibit slower growth and earlier maturation than do females. Growth in length was best described by a logistic curve, with a larger asymptotic parameter for females. In summer, concentrations of B. magister were low within the whole region, whereas in September-October squids aggregated into dense shoals over the continental slope of the Navarin-Olyutorsky region and Olyutorsky Bay. Stock structure of B. magister was complicated: each month, from 5 to 12 (usually 7-8) monthly classes of squid were encountered in the western Bering Sea. Three seasonal groups of B. magister occurred in the region: winter-, summer- and fall-hatched squids utilizing resources of the continental slope in different ways. A possible life cycle for the B. magister fall-hatched group includes a longevity of ca. 2 yr: 6 mo of embryonic development and 18 mo of postembryonic growth

Theory of second-harmonic generation in a chirped 2D nonlinear optical superlattice under nonlinear Raman-Nath diffraction

We analyze second-harmonic generation (SHG) in a two-dimensional nonlinear optical superlattice (NLOS) with its modulation period being chirped in the propagation direction and constant in the transverse direction. This results in efficient multiple SHG via nonlinear Raman–Nath diffraction. We obtain exact analytical expressions for a SH amplitude generated in chirped 2D NLOSs and for its quasi-phase-matching bandwidth. The results of analytical calculations are in excellent agreement with the numerical ones. We show that the process is robust to angular deviations of NLOS and it can be applied to enable tunable and broadband frequency conversion

Otolith chemistry reflects frontal systems in the Antarctic Circumpolar Current

Pronounced environmental trends across fronts suggest that the otolith chemistry of oceanic fish can resolve zones on either side, promoting application to population questions at similar spatial scales. Trace and minor elements laid down immediately prior to capture - along the edges of otoliths from Patagonian toothfish Dissostichus eleginoides - discriminated frontal zones in the Antarctic Circumpolar Current in the Southwestern Atlantic Ocean. Mean values differentiated sampling areas by up to 2.6 standard deviations, suggesting: (1) otolith Mg/Ca enrichment related to fish activity around the Burdwood Bank; (2) Mn/Ca enrichment associated with South America; (3) Sr/Ca linked to the presence of Circumpolar Deep Water; and (4) Ba/Ca to nutrient production and mixing. In the Polar Frontal Zone, meanders or eddies may account for affinities with neighbouring sampling areas, bringing water from the Subantarctic and Antarctic Zones onto the North Scotia Ridge. Moreover, fish age showed a significant relationship with depth and improved cross-validation by 14%, giving 85% classification rates to South American and Antarctic regions, and 57 to 83% to areas along the Patagonian Shelf. These results indicate that otolith chemistry reflects hydrography, detecting oceanic gradients across the slope of continental shelves and between zones separated by strong trends like fronts

Spatial evolution of short pulses under coherent population trapping

Spatial and temporal evolution is studied of two powerful short laser pulses having different wavelengths and interacting with a dense three-level Lambda-type optical medium under coherent population trapping. A general case of unequal oscillator strengths of the transitions is considered. Durations of the probe pulse and the coupling pulse $T_{1,2}$ ($T_2>T_1$) are assumed to be shorter than any of the relevant atomic relaxation times. We propose analytical and numerical solutions of a self-consistent set of coupled Schr\"{o}dinger equations and reduced wave equations in the adiabatic limit with the account of the first non-adiabatic correction. The adiabaticity criterion is also discussed with the account of the pulse propagation. The dynamics of propagation is found to be strongly dependent on the ratio of the transition oscillator strengths. It is shown that envelopes of the pulses slightly change throughout the medium length at the initial stage of propagation. This distance can be large compared to the one-photon resonant absorption length. Eventually, the probe pulse is completely reemitted into the coupling pulse during propagation. The effect of localization of the atomic coherence has been observed similar to the one predicted by Fleischhauer and Lukin (PRL, {\bf 84}, 5094 (2000).Comment: 16 pages revtex style, 7 EPS figures, accepted to Physical Review

Otolith Chemistry Reflects Frontal Systems in the Antarctic Circumpolar Current

Pronounced environmental trends across fronts suggest that the otolith chemistry of oceanic fish can resolve zones on either side, promoting application to population questions at similar spatial scales. Trace and minor elements laid down immediately prior to capture - along the edges of otoliths from Patagonian toothfish Dissostichus eleginoides - discriminated frontal zones in the Antarctic Circumpolar Current in the Southwestern Atlantic Ocean. Mean values differentiated sampling areas by up to 2.6 standard deviations, suggesting: (1) otolith Mg/Ca enrichment related to fish activity around the Burdwood Bank; (2) Mn/Ca enrichment associated with South America; (3) Sr/Ca linked to the presence of Circumpolar Deep Water; and (4) Ba/Ca to nutrient production and mixing. In the Polar Frontal Zone, meanders or eddies may account for affinities with neighbouring sampling areas, bringing water from the Subantarctic and Antarctic Zones onto the North Scotia Ridge. Moreover, fish age showed a significant relationship with depth and improved cross-validation by 14%, giving 85% classification rates to South American and Antarctic regions, and 57 to 83% to areas along the Patagonian Shelf. These results indicate that otolith chemistry reflects hydrography, detecting oceanic gradients across the slope of continental shelves and between zones separated by strong trends like fronts

Geometric phase and o-mode blue shift in a chiral anisotropic medium inside a Fabry-P\'erot cavity

Anomalous spectral shift of transmission peaks is observed in a Fabry--P\'erot cavity filled with a chiral anisotropic medium. The effective refractive index value resides out of the interval between the ordinary and the extraordinary refractive indices. The spectral shift is explained by contribution of a geometric phase. The problem is solved analytically using the approximate Jones matrix method, numerically using the accurate Berreman method and geometrically using the generalized Mauguin--Poincar\'e rolling cone method. The $o$-mode blue shift is measured for a 4-methoxybenzylidene-4'-$n$-butylaniline twisted--nematic layer inside the Fabry--P\'erot cavity. The twist is electrically induced due to the homeoplanar--twisted configuration transition in an ionic-surfactant-doped liquid crystal layer. Experimental evidence confirms the validity of the theoretical model.Comment: the text is available both in English (Timofeev2015en.tex) and in Russian (download: other formats - source - Timofeev2015ru.tex, Timofeev2015rus.pdf