Recent achievements in ab initio modelling of liquid water

The application of newly developed first-principle modeling techniques to liquid water deepens our understanding of the microscopic origins of its unusual macroscopic properties and behaviour. Here, we review two novel ab initio computational methods: second-generation Car-Parrinello molecular dynamics and decomposition analysis based on absolutely localized molecular orbitals. We show that these two methods in combination not only enable ab initio molecular dynamics simulations on previously inaccessible time and length scales, but also provide unprecedented insights into the nature of hydrogen bonding between water molecules. We discuss recent applications of these methods to water clusters and bulk water.Comment: 23 pages, 17 figure

Electronic signature of the instantaneous asymmetry in the first coordination shell of liquid water

Interpretation of the X-ray spectra of water as evidence for its asymmetric structure has challenged the conventional symmetric nearly-tetrahedral model and initiated an intense debate about the order and symmetry of the hydrogen bond network in water. Here, we present new insights into the nature of local interactions in water obtained using a novel energy decomposition method. Our simulations reveal that while a water molecule forms, on average, two strong donor and two strong acceptor bonds, there is a significant asymmetry in the energy of these contacts. We demonstrate that this asymmetry is a result of small instantaneous distortions of hydrogen bonds, which appear as fluctuations on a timescale of hundreds of femtoseconds around the average symmetric structure. Furthermore, we show that the distinct features of the X-ray absorption spectra originate from molecules with high instantaneous asymmetry. Our findings have important implications as they help reconcile the symmetric and asymmetric views on the structure of water.Comment: Accepted by Nature Commu

Hubungan Karakteristik Penderita dengan Kejadian Demam Tifoid pada Pasien Rawat Inap di RSUD Salewangan Maros

Introduction. Typhoid fever is an acute infectious disease of the small intestine. In Asia gained 17 million people with typhoid fever, and was found in every year there are 0.6 million deaths, or as much as 75-80% morbidity or mortality from the disease. Patients with typhoid fever in Indonesia is pretty much in the estimate 800/100.000 population per year, were found almost throughout the year, but especially in the summer. Objective. To determine the relationship of patient characteristics with the incidence of typhoid fever in hospitalized patients at the General Hospital in Salewangan Maros. Methods This type of research is survey research used an analytic approach to Cross Sectional Study. Sampling is being done with the technique of “total Sampling” noting that it going to take that all in-patients in hospitals Salewangan Maros in the period January-december 2010 with a number of 362 patients. Result. The results showed that age, sex, educational the status, and have a relationship with the incidence of typhoid fever with p value 0.000> 0.05 whereas employment the status no association with the incidence of typhoid fever with p value 0.707> 0.05 level. Conclusion. morbidity and mortality of typhoid fever can affect any age group, it should be done early prevention by immunization or vaccination where it can prevent the entry of germs and breed. Giving this information may include pamphlets, brochures, and banners, need to instill healthy behaviors that are not easilycontaminated by salmonella bacteria thypi

Pengaruh Model Pembelajaran Kooperatif Tipe Stad terhadap Kemampuan Koneksi Matematis Siswa pada Materi Pecahan

Penelitian ini bertujuan untuk mengetahui pengaruh pembelajaran kooperatif tipe STAD terhadap kemampuan koneksi matematis siswa pada materi pecahan di kelas VII SMPN 2 Subah. Metode penelitian yang digunakan adalah Quasi Experimental Design dengan rancangan penelitian Control Group Only Posttest Design. Sampel dalam penelitian ini adalah siswa kelas XA sebagai kelas kontrol dan XB sebagai kelas eksperimen. Berdasarkan uji t menggunakan program SPSS 17.0 for windows diperoleh nilai Sig. (2-tailed) = 0.01 < 0.05, yang artinya terdapat perbedaan yang signifikan kemampuan koneksi matematis antara siswa yang diberi pembelajaran menggunakan model kooperatif tipe STAD dan siswa yang diberi pembelajaran menggunakan model konvensional. Berdasarkan perhitungan Effect Size, diperoleh nilai effect size sebesar 0,8 yang artinya model pembelajaran kooperatif tipe STAD memberikan kontribusi sedang terhadap kemampuan koneksi matematis siswa. Kata kunci: Pengaruh, Kemampuan Koneksi Matematis, STAD This research aims to know the influence of STAD cooperative learning model towards the students mathematical connection ability at a fraction of material in class VII SMP 2 Subah. The method used is Quasi Experimental Design with research design Control Group Only Posttest Design. The sample in this research is students of XA as a control class and XB as a experiment class. Based on t-test using SPSS 17.0 for Windows obtained the Sig. (2-tailed) = 0.01 < α = 0.05 which means that there are significant differences between the mathematical connection ability of students who were given a STAD cooperative learning model and students are given learning using conventional model. Based on Size Effect calculation, the value of the effect size is 0.8, which means STAD cooperative learning model to contribute being on the ability of students' mathematical connections

Pemeliharaan Ikan Gurami (Osphoronemus Gouramy Lac.) Dalam Wadah Akuarium Diberi Pakan Cacing Sutra (Tubifex SP) Pada Strata Vertikal

This experiment aims to look at the effect of feeding silk worms (Tubifex sp) on the vertical strata in the aquarium container in the maintenance of carp (Osphoronemus gourami). This research was carried out for 30 days with a completely randomized design with 4 treatments and 3 repetitions. Treatment A (top feeding zone), B (middle feeding zone 1), C (middle feeding zone 2), and treatment D (zone bottom-feeding).After analyzed by ANOVA and LSD (Significant Difference) research shows that the average biomass growth body length and weight of the fish is best in treatment C respectively by 6.82 cm and 3.30 grams of the water level 10 cm zone of basic aquarium (P <0.5). While the average percentage of the best survival was also contained in C treatment that is equal to 98%

Model of strategic planning in active systems

Annotation The work is dedicated to the mathematical formulation of the needing for strategic planning in active systems. At the same time, the possibility of the TAC (theory of active systems) for an assessment of conditions of effective strategic planning and development of an active system are shown.Keywords Active system, strategic planning, condition of open management, condition ofNDA, TAS

Ab initio quality neural-network potential for sodium

An interatomic potential for high-pressure high-temperature (HPHT) crystalline and liquid phases of sodium is created using a neural-network (NN) representation of the ab initio potential energy surface. It is demonstrated that the NN potential provides an ab initio quality description of multiple properties of liquid sodium and bcc, fcc, cI16 crystal phases in the P-T region up to 120 GPa and 1200 K. The unique combination of computational efficiency of the NN potential and its ability to reproduce quantitatively experimental properties of sodium in the wide P-T range enables molecular dynamics simulations of physicochemical processes in HPHT sodium of unprecedented quality.Comment: 8 pages, 11 figures, 2 table