Effective transport barriers in nontwist systems

In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. These barriers have been identified in symplectic nontwist maps that model such zonal flows. We use the so-called standard nontwist map, a paradigmatic example of nontwist systems, to analyze the parameter dependence of the transport through a broken shearless barrier. On varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Moreover, we show how these stickiness structures, and the concomitant transport reduction in the shearless region, are determined by a homoclinic tangle of the remaining dominant twin island chains. We use the finite-time rotation number, a recently proposed diagnostic, to identify transport barriers that separate different regions of stickiness. The identified barriers are comparable to those obtained by using finite-time Lyapunov exponents.FAPESPCNPqCAPESMCT/CNEN (Rede Nacional de Fusao)Fundacao AraucariaUS Department of Energy DE-FG05-80ET-53088Physic

Hanbury Brown Twiss effect for ultracold quantum gases

We have studied 2-body correlations of atoms in an expanding cloud above and below the Bose-Einstein condensation threshold. The observed correlation function for a thermal cloud shows a bunching behavior, while the correlation is flat for a coherent sample. These quantum correlations are the atomic analogue of the Hanbury Brown Twiss effect. We observe the effect in three dimensions and study its dependence on cloud size.Comment: Figure 1 availabl

Somatic development and embryo yield in crossbred F1 mice generated by different mating strategies.

The aim of this study was to evaluate different mating strategies among endogamic strains to create F1 populations of mice, minimising the effect of inbreeding depression on somatic development and embryo yield. Females from the strains Swiss, CBA and C57Bl/6 were divided in nine experimental mate arrangements. The total numbers of pups born alive per dam and somatic development, estimated by weighing and measuring the crown-rump length, were recorded. Superovulation response was evaluated in outbreed females. Litter size differed among endogamic dams, irrespective of the sire. Somatic development results suggest heterosis and imprinting phenomena, once a differential parental effect was demonstrated. There was no difference in corpora lutea, ova or embryos recovered (P > 0.05), but recovery and viability rates differ among F1 groups (P < 0.05). The association of dam prolificity with somatic development and superovulation response of the pups should be considered for experimental F1 populations establishment. The use of outbreed animals, however, did not reduce response variability to hormone treatment

Tugas dan Tanggung Jawab Syahbandar dalam Kegiatan Pengangkutan Laut di Indonesia

Permasalahan yang diteliti dalam penulisan hukum ini adalaah apa saja tugas dan tanggung jawab yang dimiliki syahbandar dalam kegiatan pengangkutan laut di Indonesia. Penelitian ini menggunakan metode yuridis normatif. Penelitian ini menyimpulkan tugas syahbandar dalam keamanan dan keselamatan pelayaran berdasarkan hukum Indonesia adalah sebagai penegak hukum di bidang keselamatan dan keamanan pelayaran Indonesia, sebagai kepala pemerintahan dalam pelabuhan atau koordinator segala aktivitas dalam pelabuhan, sebagai pengawas dan penanggung jawab keamanan dan keselamatan pelayaran di Indonesia, dan sebagai penerbit dokumen pelayaran. Ttanggung jawab syahbandar dalam keamanan dan keselamatan pelayaran berdasarkan hukum Indonesia adalah, memastikan sebuah kapal layak untuk berlayar dan meminimalisir kemungkinan terjadinya kecelakaan kapal akibat tidak laiklautnya kapal, menanggulangi pencemaran laut dan melakukan upaya untuk mencegah pencemaran laut terjadi, dan ikut serta dalam pencarian dan penyelamatan korban apabila terjadi kecelakaan kapal ataupun saat ada gangguan dalam pelayaran. Saran yang dapat diberikan penulis adalah peningkatan kemampuan syahbandar melalui keterampilan nautis, teknis dan administratif serta disiplin kerja, peningkatan dedikasi terhadap pengembangan tugas demi terwujudnya keselamatan kapal, barang dan keselamatan jiwa di laut, dan dilakukan evaluasi kinerja bagi setiap Syahbandar yang dilaksanakan setiap periode waktu tertentu

Getting the elastic scattering length by observing inelastic collisions in ultracold metastable helium atoms

We report an experiment measuring simultaneously the temperatureand the flux of ions produced by a cloud of triplet metastablehelium atoms at the Bose-Einstein critical temperature. The onsetof condensation is revealed by a sharp increase of the ion fluxduring evaporative cooling. Combining our measurements withprevious measurements of ionization in a pure BEC,we extract an improved value of the scattering length$a=11.3^{+2}_{-1}$ nm. The analysis includes corrections takinginto accountthe effect of atomic interactions on the criticaltemperature, and thus an independent measurement of the scatteringlength would allow a new test of these calculations