Two-dimensional frustrated spin systems in high magnetic fields

We discuss our numerical results on the properties of the S = 1/2 frustrated J1-J2 Heisenberg model on a square lattice as a function of temperature and frustration angle phi = atan(J2/J1) in an applied magnetic field. We cover the full phase diagram of the model in the range -pi <= phi <= pi. The discussion includes the parameter dependence of the saturation field itself, and addresses the instabilities associated with it. We also discuss the magnetocaloric effect of the model and show how it can be used to uniquely determine the effective interaction constants of the compounds which were investigated experimentally.Comment: 4 pages, 5 figures, proceedings of RHMF 200

Using non-convex approximations for efficient analysis of timed automata

The reachability problem for timed automata asks if there exists a path from an initial state to a target state. The standard solution to this problem involves computing the zone graph of the automaton, which in principle could be infinite. In order to make the graph finite, zones are approximated using an extrapolation operator. For reasons of efficiency in current algorithms extrapolation of a zone is always a zone and in particular it is convex. In this paper, we propose to solve the reachability problem without such extrapolation operators. To ensure termination, we provide an efficient algorithm to check if a zone is included in the so called region closure of another. Although theoretically better, closure cannot be used in the standard algorithm since a closure of a zone may not be convex. An additional benefit of the proposed approach is that it permits to calculate approximating parameters on-the-fly during exploration of the zone graph, as opposed to the current methods which do it by a static analysis of the automaton prior to the exploration. This allows for further improvements in the algorithm. Promising experimental results are presented.Comment: Extended version of FSTTCS 2011 pape

Effect of V-shaped Ribs on Internal Cooling of Gas Turbine Blades

Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature. The rotor inlet temperatures in most gas turbines are far higher than the melting point of the blade material. Hence the turbine blades need to be cooled. In this work, simulations were carried out with the leading edge of gas turbine blade being internally cooled by coolant passages with V-shaped ribs at angles of 30°, 45° or 60° and at three aspect ratios (1:1, 1:2 and 2:3). The trailing edge of the blade was cooled by cylindrical and triangular pin-fin perforations in staggered and inline arrangements. Numerical analyses were carried out for each configuration of the cooling passages. The best cooling passages for leading edge and trailing edge were deduced by comparing the results of these analyses. It was found that using V-shaped ribs and fins induces a swirling flow, which in turn increases the velocity gradient and hence produces an improvement in heat transfer. The results show that under real time flow conditions, the application of V-shaped ribs and pin-fin perforations is a very promising technique for improving blade life

Perancangan Pusat Informasi Adat Dan Budaya Sabu-Raijua : Transformasi Kampung Adat

Setiap daerah dan suku yang berdia, di Indonesia memiliki kearifam local yang berbeda-beda. Nusa Tenggara Timur merupakan salah satu kepulauan yang kayak suku dan budaya. Salah satu Suku besar di Pulau ini adalah Suku Sabu. Suku Sabu memiliki keunikan dari segi kultur dan budaya. Hal ini tidak hanya tercermin dalam seni namun telah menjadi cara hidup. Masyarakat Sabu memiliki pola permukiman dan cara hidup yang khas. Mereka adalah para pelaut ulung sehingga diimplementasikan dalam caranya bermukim dan membangun permukiman atau kampung Adat. Pulau Sabu –Raijua juga telah menjadi salah satu daya tarik bagi wisatawan mancanegara.Selain itu banyak masyarakat Sabu yang telah keluar dan merantau di tanah lain sehingga seringkali mereka tidak mendapatkan informasi tentang adat dan budaya Sabu. Dengan banyaknya wisatawan baik dari dalam dan luar negeri yang datang dan menurunnya kesadaran memiliki dan bangga akan budaya sendiri maka diperlukanlah perencanaan Pusat Informasi Adat dan Budaya masyarakat Sabu-Raijua.Perencaan Pusat Informasi Adat dan Budaya beridentitas kearifan local sehingga digunakan metode transformasi. Perancangan ini mentrasformasi penataan, bentukan fisik dan tampilang dari Kampung Adat yang biasa disebut “Rae Kowa” atau Kampung Perahu

Integrating sexual and reproductive health into health system strengthening in humanitarian settings: a planning workshop toolkit to transition from minimum to comprehensive services in the Democratic Republic of Congo, Bangladesh, and Yemen.

BackgroundPlanning to transition from the Minimum Initial Service Package for Sexual and Reproductive Health (SRH) toward comprehensive SRH services has been a challenge in humanitarian settings. To bridge this gap, a workshop toolkit for SRH coordinators was designed to support effective planning. This article aims to describe the toolkit design, piloting, and final product.MethodsAnchored in the Health System Building Blocks Framework of the World Health Organization, the design entailed two complementary and participatory strategies. First, a collaborative design phase with iterative feedback loops involved global partners with extensive operational experience in the initial toolkit conception. The second phase engaged stakeholders from three major humanitarian crises to participate in pilot workshops to contextualize, evaluate, validate, and improve the toolkit using qualitative interviews and end-of-workshop evaluations. The aim of this two-phase design process was to finalize a planning toolkit that can be utilized in and adapted to diverse humanitarian contexts, and efficiently and effectively meet its objectives. Pilots occurred in the Democratic Republic of Congo for the Kasai region crisis, Bangladesh for the Rohingya humanitarian response in Cox's Bazar, and Yemen for selected Governorates.ResultsResults suggest that the toolkit enabled facilitators to foster a systematic, participatory, interactive, and inclusive planning process among participants over a two-day workshop. The approach was reportedly effective and time-efficient in producing a joint work plan. The main planning priorities cutting across settings included improving comprehensive SRH services in general, healthcare workforce strengthening, such as midwifery capacity development, increasing community mobilization and engagement, focusing on adolescent SRH, and enhancing maternal and newborn health services in terms of quality, coverage, and referral pathways. Recommendations for improvement included a dedicated and adequately anticipated pre-workshop preparation to gather relevant data, encouraging participants to undertake preliminary study to equalize knowledge to partake fully in the workshop, and enlisting participants from marginalized and underserved populations.ConclusionCollaborative design and piloting efforts resulted in a workshop toolkit that could support a systematic and efficient identification of priority activities and services related to comprehensive SRH. Such priorities could help meet the SRH needs of communities emerging from acute humanitarian situations while strengthening the overall health system

Acute Toxicity and Vascular Properties of Seed of Parkia Biglobosa (Jacq) R. Br Gift (Mimosaceae) on Rat Aorta

The authors report here the results of study on Parkia biglobosa seeds used in Burkina Faso for arterial hypertension treatment. Investigations were done on acute toxicity and vascular properties of fermented and roasted seeds. Acute toxicity test using mice, revealed by the intraperitoneal route a lethal dose 50 (LD50) of 1800 mg/kg and 1600 mg/kg of body weight for aqueous extract from roasted and fermented seeds respectively. According to the scale of Hodge and Sterner and that of the World Health Organization, such drugs would be classified lightly toxic. Oral administration (up to 3000 mg/kg) did not induce any death of animal. For the vascular properties, the effects of these products were tested on the aorta isolated from rats. The cumulative administration of extract from roasted and fermented seeds (0.1-10 mg/mL) in an organ bath induced a concentration-dependent relaxation of the aorta pre contracted by phenylephrine, with or without functional endothelium. The extracts (10 mg/mL) inhibited for 100% the contraction induced by phenylephrine. The EC50 values in presence and absence of endothelium were respectively of 5.37 &plusmn; 0.12 and 4.19 &plusmn; 1.02 mg/mL for fermented seeds; for roasted seeds these values were respectively, 5.39 &plusmn; 1.12 and 5.93 &plusmn; 0.95 mg/mL. Nevertheless, low concentration of roasted seeds (1-4 mg/mL) induced endothelium-dependent relaxation and this effect was inhibited by indomethacin (10-5M), and not by L-NAME (310-4M). These experimental results revealed a vasorelaxant effect of P. biglobosa seeds. P. biglobosa seems to act directly on the smooth muscle and via endothelium involving the generation of vasodilatating prostaglandins. This vasodilator effect would be in favor of an anti hypertensive property of P. biglobosa seeds.Key words: Acute toxicity; vasodilator; endothelium; Parkia biglobosa

HPLC Method for Determination of p-coumaric acid from the Medicinal Herb Leptadinia reticulata

The aim of present study was to develop and validate a simple, precise and rapid HPLC method for the quantification of p-coumaric acid in Leptadinia reticulata extractst. The analysis was performed by reverse-phase chromatography on an phenomenex C18 columns with isocratic elution of Methanol and 0.8%-Formic acid in water (6:4) at a flow rate of 1.0mL/min, a column temperature of 35°C, photodiode array detector detection at 326 nm. The method validated in terms of linearity accuracy precision LOD, LOQ and stability. The herb Leptidinia reticulata contains 0.17% p-coumaric acid. The linear range of method was 0.25-50µg/ml with correlation coefficient of 0.9993, the recovery was 98-99.4% and the relative standard deviation is 0.98 % (n=6). The developed method was found to be a relatively simple, precise and reproducible for the quantification of p-coumaric acid. The method does not employ any derivatization procedure and can be used as a quality control tool for the routine analysis of    p-coumaric acid from an herb Leptadinia reticulata

CeRuPO: A rare example of a Ferromagnetic Kondo lattice

We have determined the physical ground state properties of the compounds CeRuPO and CeOsPO by means of magnetic susceptibility chi(T), specific heat C(T), electrical resistivity rho(T), and thermopower S(T) measurements. chi(T) reveals a trivalent 4f1 cerium state in both compounds. For CeRuPO a pronounced decrease of rho(T) below 50K indicates the onset of coherent Kondo scattering which is confirmed by enhanced S(T). The temperature and magnetic field dependence of chi(T) and C(T) evidence ferromagnetic (FM) order at TC=15K. Thus, CeRuPO seems to be one of the rare example of a FM Kondo lattice. In contrast, CeOsPO shows antiferromagnetic order at TN=4.4K despite only minor changes in lattice parameters and electronic configuration. Additional 31P NMR results support these scenarios. LSDA+U calculations evidence a quasi two dimensional electronic band structure, reflecting a strong covalent bonding within the CeO and RuP layers and a weak ionic like bonding between the layers.Comment: accepted in Phys. Rev. B, high quality figures: http://www.cpfs.mpg.de/~krellner