9,510 research outputs found
Short-range stationary patterns and long-range disorder in an evolution equation for one-dimensional interfaces
A novel local evolution equation for one-dimensional interfaces is derived in
the context of erosion by ion beam sputtering. We present numerical simulations
of this equation which show interrupted coarsening in which an ordered cell
pattern develops with constant wavelength and amplitude at intermediate
distances, while the profile is disordered and rough at larger distances.
Moreover, for a wide range of parameters the lateral extent of ordered domains
ranges up to tens of cells. This behavior is new in the context of dynamics of
surfaces or interfaces with morphological instabilities. We also provide
analytical estimates for the stationary pattern wavelength and mean growth
velocity
Studies on reproduction of the mullet Mugil platanus GĂĽnther, 1880 (Actinopterygii, Mugilidae) from the Mar Chiquita coastal lagoon, Argentina: Similarities and differences with related species
The aim of the present study is to provide the first results on the reproductive biology of Mugil platanus, from the Mar Chiquita coastal lagoon (Argentina). To address this topic, we employed mainly female gonads, at both microscopic and macroscopic levels. The following stages of oocyte development were observed: (A) oogonias, (B) primary growth oocyte, (C) cortical alveolus stage, (D) yolked oocytes, and (E) atretic follicle. Also five of the seven stages of gonad maturity were macro and microscopically stated. The potential fecundity ranged between 1,002,026 and 2,548,769 yolked oocytes, with a mean of around 1,800,000 oocytes. The length at first maturity (L 50) was 450.6 total length (TL) and 367.7 standard length (SL) for females, 436.3 TL and 354.9 SL for males, showing a late sexual maturity for both sexes. Seasonal changes in gonadosomatic index (GSI) of females were observed. The mean GSI was ≤1 during six months of the year (January, June-October). Two modes in the ovarian maturation were observed, the most important in April-May and a secondary one in November-December. Both modes, correlated with the CPUE values, are indicative of the mullet migration from the coastal lagoon towards the sea for spawning. Differences and similarities have been found between Mugil platanus and other mugilid species (Mugil cephalus, Mugil curema, Liza aurata, Liza abu, Liza argentea, Myxus elongatus, and Valamugil cunnesius), from the reproductive point of view. The length at first maturity obtained for M. platanus is higher than in other mugilid species and when a relationship between maximum length and L 50 is established the percentage corresponding to Mugil platanus is 75%, while the others range between 50 and 61%.Fil: González Castro, Mariano. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Marinas; Argentina. Universidad AutĂłnoma Metropolitana-Iztapalapa; MĂ©xicoFil: Macchi, Gustavo Javier. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Subsede Instituto Nacional de InvestigaciĂłn y Desarrollo Pesquero; ArgentinaFil: Cousseau, MarĂa Berta. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Marinas; Argentin
Non-linear ripple dynamics on amorphous surfaces patterned by ion-beam sputtering
Erosion by ion-beam sputtering (IBS) of amorphous targets at off-normal
incidence frequently produces a (nanometric) rippled surface pattern, strongly
resembling macroscopic ripples on aeolian sand dunes. Suitable generalization
of continuum descriptions of the latter allows us to describe theoretically for
the first time the main nonlinear features of ripple dynamics by IBS, namely,
wavelength coarsening and non-uniform propagation velocity, that agree with
similar results in experiments and discrete models. These properties are seen
to be the anisotropic counterparts of in-plane ordering and (interrupted)
pattern coarsening in IBS experiments on rotating substrates and at normal
incidence.Comment: 5 pages, 3 figure
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