Pattern-induced anchoring transitions in nematic liquid crystals

In this paper we revisit the problem of a nematic liquid crystal in contact with patterned substrates. The substrate is modelled as a periodic array of parallel infinite grooves of well-defined cross section sculpted on a chemically homogeneous substrate which favors local homeotropic anchoring of the nematic. We consider three cases: a sawtooth, a crenellated and a sinusoidal substrate. We analyse this problem within the modified Frank-Oseen formalism. We argue that, for substrate periodicities much larger than the extrapolation length, the existence of different nematic textures with distinct far-field orientations, as well as the anchoring transitions between them, are associated with the presence of topological defects either on or close to the substrate. For the sawtooth and sinusoidal case, we observe a homeotropic to planar anchoring transition as the substrate roughness is increased. On the other hand, a homeotropic to oblique anchoring transition is observed for crenellated substrates. In this case, the anchoring phase diagram shows a complex dependence on the substrate roughness and substrate anchoring strength.Comment: 36 pages, 15 figures, revised version submitted to Journal of Physics: Condensed Matte

PENGGUNAAN FILLER ABU SERBUK KAYU KELAPA PADA ASPAL BETON AC-WC

Jalan adalah salah satu prasarana transportasi yang sangat penting pada kemajuan dan pembangunan untuk kehidupan masyrakat. Struktur perkerasan jalan mempunyai peran penting dalam memberi pelayanan yang optimal agar masyrakat dapat menikmati jalan dengan nyaman dan cepat agar sampai dengan tempat tujuan  agar dapat tercipta pemerataan pembangunan. Pada spefikasi ini adalah adalah lapisan aspal beton (laston) atau asphalt concrete (AC). Lapisan Asphalt Concrete –Wearing Course (AC-WC) adalah lapisan paling atas yang terdiri dari strukutur pekerasan jalan raya yang berhubungan langsung dengan kendaraan dan mempunyai strutur paling halus. Bahan utama penyusun pekerasan jalan adalah agregat kasar, agregat halus, aspal dan bahan pengisi atau filler. Pemakaian bahan filler dengan berat jenis yang lebih kecil dibandingkan dengan berat jenis agregat kasar dan agregat halus dapat menyebabkan campuran menjadi kurang aspal. Penelitian ini bertujuan untuk menganalisis Kadar Aspal Optimal penggunaan abu serbuk kayu sebagai bahan pengganti filler di dalam campuran aspal AC-WC. Dalam penelitian ini direncanakan campuran serbuk abu kelapa sebagai penambah bahan filler dengan masing masing campuran sebesar 50% dan 80% abu serbuk kelapa. Dari hasil penelitian diperoleh nilai kinerja campuran aspal pada kadar aspal optimum (KAO) ditinjau dari keenam nilai karakteristik marshall, yaitu nilai VIM, VMA, VFB, Stabilitas, Flow dan Marshall Quotient, Filler 50% abu serbuk kayu kelapa memiliki kinerja yang lebih baik dibandingkan dengan campuran filler 80% abu serbuk kayu kelapa

Zinc abundances in Galactic bulge field red giants: implications for DLA systems

Zinc in stars is an important reference element because it is a proxy to Fe in studies of damped Lyman-alpha systems, permitting a comparison of chemical evolution histories of bulge stellar populations and DLAs. In terms of nucleosynthesis, it behaves as an alpha element because it is enhanced in metal-poor stars. The aim of this work is to derive the iron-peak element Zn abundances in 56 bulge giants from high resolution spectra. These results are compared with data from other bulge samples, as well as from disk and halo stars, and damped Lyman-alpha systems, in order to better understand the chemical evolution in these environments. High-resolution spectra were obtained using FLAMES+UVES on the Very Large Telescope. We find [Zn/Fe]=+0.24+-0.02 in the range -1.3 < [Fe/H] < -0.5 and [Zn/Fe]=+0.06+-0.02 in the range -0.5 < [Fe/H] -0.1, it shows a spread of -0.60 < [Zn/Fe] < +0.15, with most of these stars having low [Zn/Fe]<0.0. These low zinc abundances at the high metallicity end of the bulge define a decreasing trend in [Zn/Fe] with increasing metallicities. A comparison with Zn abundances in DLA systems is presented, where a dust-depletion correction was applied for both Zn and Fe. Finally, we present a chemical evolution model of Zn enrichment in massive spheroids, representing a typical classical bulge.Comment: Accepted in Astronomy & Astrophysics, in press Date of acceptance: 13/05/2015. 19 pages, 14 Figs in Astronomy & Astrophysics, 201

κ\kappa-Deformed quantum and classical mechanics for a system with position-dependent effective mass

We present the quantum and classical mechanics formalisms for a particle with position-dependent mass in the context of a deformed algebraic structure (named $\kappa$-algebra), motivated by the Kappa-statistics. From this structure we obtain deformed versions of the position and momentum operators, which allow to define a point canonical transformation that maps a particle with constant mass in a deformed space into a particle with position-dependent mass in the standard space. We illustrate the formalism with a particle confined in an infinite potential well and the Mathews-Lakshmanan oscillator, exhibiting uncertainty relations depending on the deformation

Studies of transport coefficients in charged AdS4_{4} black holes on κ\kappa-deformed space

In this work, we study the effect of $\kappa$-deformed space on the thermodynamic quantities, this are find through the holographic renormalization that provide the free energy, which is fundamental to derive the another thermodynamic quantities. For this scenario we consider an charged AdS$_{4}$ black hole for an Einstein-Maxwell model where the derivative quadrivector is replaced by a deformed version inspired in Kaniadakis statistics. Besides, we extract the transport coefficient know as electrical conductivity.Comment: 5 pages, 8 figure