Free energy calculations of elemental sulphur crystals via molecular dynamics simulations

Free energy calculations of two crystalline phases of the molecular compound S8 were performed via molecular dynamics simulations of these crystals. The elemental sulphur S8 molecule model used in our MD calculations consists of a semi-flexible closed chain, with fixed bond lengths and intra-molecular potentials for its bending and torsional angles. The intermolecular potential is of the atom-atom Lennard-Jones type. Two free energy calculation methods were implemented: the accurate thermodynamic integration method proposed by Frenkel and Ladd and an estimation that takes into account the contribution of the zero point energy and the entropy of the crystalline vibrational modes to the free energy of the crystal. The last estimation has the enormous advantage of being easily obtained from a single MD simulation. Here we compare both free energy calculation methods and analyze the reliability of the fast estimation via the vibrational density of states obtained from constrained MD simulations. New results on alpha- and alpha'- S8 crystals are discussedComment: 18 pages, 2 figures, submitted to J. Chem. Phy

Ускоренное старение сабельника болотного COMARUM PALUSTRE L..

САБЕЛЬНИК БОЛОТНЫ

Pattern-Based Genetic Algorithm for Airborne Conflict Resolution

NASA has developed the Autonomous Operations Planner (AOP) airborne decision support tool to explore advanced air traffic control concepts that include delegating separation authority to aircraft. A key element of the AOP is its strategic conflict resolution (CR) algorithm, which must resolve conflicts while maintaining conformance with traffic flow management constraints. While a previous CR algorithm, which focused on broader flight plan optimization objectives as a part of conflict resolution, had successfully been developed, new research has identified the need for resolution routes the users find more acceptable (i.e., simpler and more intuitive). A new CR algorithm is presented that uses a combination of pattern-based maneuvers and a genetic algorithm to achieve these new objectives. Several lateral and vertical maneuver patterns are defined and the application of the genetic algorithm explained. A new approach to defining a conflicted fitness function using estimates of the local conflict region around a conflicted trajectory is also presented. Preliminary performance characteristics of the implemented algorithm are provided

Laboratory and in situ assays of digital image analysis based protocols for biodeteriorated rock and mural paintings recording

8 pages, 8 figures, 43 references.Rock art paintings, and in general mural paintings, are one of the many elements of cultural heritage complex systems. As the different elements of a system have diverse spatial positions, spatial recording allows understanding their interactions. Thus, a useful approach to mural paintings recording is to understand it as a microcartography issue, managing each element of the system as a cartographic coverage. The approach implemented emphasizes the utilization of data obtained by remote sensing techniques for extracting different kinds of information susceptible of being analysed, classified and plotted in a differentiate way by means of the possibility of reducing redundant data by Principal Component Analysis (PCA) and the elaboration of false-colour images from uncorrelated bands. A laboratory model was prepared in order to simulate biodeterioration of rock art. The samples were photographically recorded thereafter under different lighting conditions, and PCA applied to the resulting images. False-colour images obtained by combining Principal Component bands allowed us to reach results similar to those of an unsupervised classification. The method has been applied to Roman mural paintings from one of the tombs of Carmona Necropolis, obtaining good results.Peer reviewe

The Crescent Student Newspaper, March 4, 1991

Student newspaper of Pacific College (later George Fox University). 8 pages, black and white.https://digitalcommons.georgefox.edu/the_crescent/2063/thumbnail.jp

Using image analysis software (ias) for the technological characterization of archaeological ceramics: scope, limitations and perspectives

El software de análisis de imágenes (SAI) se ha empezado a utilizar en los últimos años crecientemente en arqueología. Las principales aplicaciones observadas han sido en los análisis de arte rupestre y cerámicas arqueológicas. La manipulación de las imágenes obtenidas por diferentes medios (cámaras digitales, escáners, microscopía electrónica de barrido, lupas binoculares y microscopios polarizadores) ha permitido maximizar la información contenida en cada una de ellas. En este trabajo presentamos una evaluación y testeo de la aplicación del SAI en la caracterización tecnológica de seis fragmentos de cerámicas arqueológicas pertenecientes a la Cultural Saujil del Período Agroalfarero Temprano (a.C. 200-400 d.C.) del noroeste argentino. Asimismo, se discuten críticamente los principales alcances y limitaciones de esta aproximación metodológica.Image analysis software (IAS) has been increasingly applied in archaeology over the last years. The main observed applications have been in rock art studies and archaeological ceramic analyses. The manipulation of images obtained by different means, such as digital cameras, scanners, scanning electron microscopy, binocular and petrographic microscopes, has allowed to maximize the information contained in each of the images obtained. In this paper, we present an evaluation and testing of the application of IAS for the technological characterization of six archaeological sherds belonging to Saujil Culture from the Early Period (200 BC- AD 400) in the Northwestern region of Argentine. We also discuss the main scopes and limitations of this methodological approach.Fil: de la Fuente, Guillermo Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Catamarca. Escuela de Arqueología; ArgentinaFil: Vera, Sergio David. Universidad Nacional de Catamarca. Escuela de Arqueología; Argentin

Using late-time optical and near-infrared spectra to constrain Type Ia supernova explosion properties

The late-time spectra of Type Ia supernovae (SNe Ia) are powerful probes of the underlying physics of their explosions. We investigate the late-time optical and near-infrared spectra of seven SNe Ia obtained at the VLT with XShooter at $>$200 d after explosion. At these epochs, the inner Fe-rich ejecta can be studied. We use a line-fitting analysis to determine the relative line fluxes, velocity shifts, and line widths of prominent features contributing to the spectra ([Fe II], [Ni II], and [Co III]). By focussing on [Fe II] and [Ni II] emission lines in the ~7000-7500 \AA\ region of the spectrum, we find that the ratio of stable [Ni II] to mainly radioactively-produced [Fe II] for most SNe Ia in the sample is consistent with Chandrasekhar-mass delayed-detonation explosion models, as well as sub-Chandrasekhar mass explosions that have metallicity values above solar. The mean measured Ni/Fe abundance of our sample is consistent with the solar value. The more highly ionised [Co III] emission lines are found to be more centrally located in the ejecta and have broader lines than the [Fe II] and [Ni II] features. Our analysis also strengthens previous results that SNe Ia with higher Si II velocities at maximum light preferentially display blueshifted [Fe II] 7155 \AA\ lines at late times. Our combined results lead us to speculate that the majority of normal SN Ia explosions produce ejecta distributions that deviate significantly from spherical symmetry.Comment: 17 pages, 12 figure, accepted for publication in MNRA

Berkala arkeologi sangkhakala: vol.21 No.1, Mei 2018

Sangkhakalaterdiri dari dua kata yaitu Sangkhadan Kala. Sangkhaadalah sebutan dalam Bahasa Sansekerta untuk jenis kerang atau siput laut. Sangkhadalam mitologi Hindhu digunakan sebagai atribut dewa dalam sekte Siwa dan Wisnu. Sedangkan Kalaberarti waktu, ketika atau masa. Jadi Sangkhakalamerupakan alat dari keranglaut yang mengeluarkan suara sebagai tanda bahwa waktu telah tiba untuk memulai suatu tugas atau pekerjaan. Berkenaan dengan itu, BERKALA ARKEOLOGI SANGKHAKALA merupakan istilah yang dikiaskan sebagai terompet ilmuwan arkeologi dalam menyebarluaskan arti dan makna ilmu arkeologi sehingga dapat dinikmati oleh kalangan ilmuwan khususnya dan masyarakat luas umumnya. Selain itu juga merupakan wadah informasi bidang arkeologi yang ditujukan untuk memajukan arkeologi maupun kajian ilmu lain yang terkait. Muatannya adalah hasil penelitian,tinjauan arkeologi dan ilmu terkait. Dalam kaitannya dengan penyebarluasan informasi dimaksud, redaksi menerima sumbangan artikel dalam BahasaIndonesia maupun asing yang dianggap berguna bagi perkembangan ilmu arkeologi. Berkala Arkeologi ini diterbitkan dua kali dalam setahun yaitu pada bulan Mei dan Novembe

Sucrose diffusion in aqueous solution.

The diffusion of sugar in aqueous solution is important both in nature and in technological applications, yet measurements of diffusion coefficients at low water content are scarce. We report directly measured sucrose diffusion coefficients in aqueous solution. Our technique utilises a Raman isotope tracer method to monitor the diffusion of non-deuterated and deuterated sucrose across a boundary between the two aqueous solutions. At a water activity of 0.4 (equivalent to 90 wt% sucrose) at room temperature, the diffusion coefficient of sucrose was determined to be approximately four orders of magnitude smaller than that of water in the same material. Using literature viscosity data, we show that, although inappropriate for the prediction of water diffusion, the Stokes-Einstein equation works well for predicting sucrose diffusion under the conditions studied. As well as providing information of importance to the fundamental understanding of diffusion in binary solutions, these data have technological, pharmaceutical and medical implications, for example in cryopreservation. Moreover, in the atmosphere, slow organic diffusion may have important implications for aerosol growth, chemistry and evaporation, where processes may be limited by the inability of a molecule to diffuse between the bulk and the surface of a particle