Experimental design of an interlaboratory study for trace metal analysis of liquid fluids

The accurate determination of trace metals and fuels is an important requirement in much of the research into and development of alternative fuels for aerospace applications. Recognizing the detrimental effects of certain metals on fuel performance and fuel systems at the part per million and in some cases part per billion levels requires improved accuracy in determining these low concentration elements. Accurate analyses are also required to ensure interchangeability of analysis results between vendor, researcher, and end use for purposes of quality control. Previous interlaboratory studies have demonstrated the inability of different laboratories to agree on the results of metal analysis, particularly at low concentration levels, yet typically good precisions are reported within a laboratory. An interlaboratory study was designed to gain statistical information about the sources of variation in the reported concentrations. Five participant laboratories were used on a fee basis and were not informed of the purpose of the analyses. The effects of laboratory, analytical technique, concentration level, and ashing additive were studied in four fuel types for 20 elements of interest. The prescribed sample preparation schemes (variations of dry ashing) were used by all of the laboratories. The analytical data were statistically evaluated using a computer program for the analysis of variance technique

FTIR analysis of aviation fuel deposits

Five modes of operation of the Nicolet 7199 Fourier Transform Infrared Spectrophotometer have been evaluated for application in analysis of the chemical structure of accelerated storage/thermal deposits produced by jet fuels. Using primarily the absorption and emission modes, the effects of fuel type, stress temperature, stress time, type of spiking agent, spiking agent concentration, fuel flow, and post-depositional treatment on the chemical nature of fuel deposits have been determined

Quasinormal Quantization in deSitter Spacetime

A scalar field in four-dimensional deSitter spacetime (dS_4) has quasinormal modes which are singular on the past horizon of the south pole and decay exponentially towards the future. These are found to lie in two complex highest-weight representations of the dS_4 isometry group SO(4,1). The Klein-Gordon norm cannot be used for quantization of these modes because it diverges. However a modified `R-norm', which involves reflection across the equator of a spatial S^3 slice, is nonsingular. The quasinormal modes are shown to provide a complete orthogonal basis with respect to the R-norm. Adopting the associated R-adjoint effectively transforms SO(4,1) to the symmetry group SO(3,2) of a 2+1-dimensional CFT. It is further shown that the conventional Euclidean vacuum may be defined as the state annihilated by half of the quasinormal modes, and the Euclidean Green function obtained from a simple mode sum. Quasinormal quantization contrasts with some conventional approaches in that it maintains manifest dS-invariance throughout. The results are expected to generalize to other dimensions and spins.Comment: 23 pages. v2: minor edits, matches published versio

Transmission channels for light in absorbing random media: from diffusive to ballistic-like transport

While the absorption of light is ubiquitous in nature and in applications, the question remains how absorption modifies the transmission channels in random media. We present a numerical study on the effects of optical absorption on the maximal transmission and minimal reflection channels in a two-dimensional disordered waveguide. In the weak absorption regime, where the system length is less than the diffusive absorption length, the maximal transmission channel is dominated by diffusive transport and it is equivalent to the minimal reflection channel. Its frequency bandwidth is determined by the underlying quasimode width. However, when the absorption is strong, light transport in the maximal transmission channel undergoes a sharp transition and becomes ballistic-like transport. Its frequency bandwidth increases with absorption, and the exact scaling varies with the sample's realization. The minimal reflection channel becomes different from the maximal transmission channel and becomes dominated by absorption. Counterintuitively, we observe in some samples that the minimum reflection eigenvalue increases with absorption. Our results show that strong absorption turns open channels in random media from diffusive to ballistic-like.Comment: 11 pages, 7 figure

The politics of (de)liberalization: studying partisan effects using mixed-effects models

Liberalization is a perennial topic in politics and political science. We first review a broad scholarly debate, showing that the mainstream theories make rival and contradictory claims regarding the role of political parties in (de)liberalization reforms. We then develop a framework of conditional partisan influence, arguing that and under what conditions parties matter. We test our (and rival) propositions with a new dataset on (de)liberalization reforms in 23 democracies since 1973 covering several policy areas. Methodologically, we argue that existing quantitative studies are problematic: They rely on time-series cross-section models using country-year observations; but governments do not change annually, so that the number of observations is artificially inflated, resulting in incorrect estimates. We propose mixed-effects models instead, with country-year observations nested in cabinets, which are nested in countries and years. The results show under what conditions parties matter for (de)liberalization. More generally, the paper argues that mixed-effects models should become the new standard for studying partisan influences

Critical Fidelity

Using a Wigner Lorentzian Random Matrix ensemble, we study the fidelity, $F(t)$, of systems at the Anderson metal-insulator transition, subject to small perturbations that preserve the criticality. We find that there are three decay regimes as perturbation strength increases: the first two are associated with a gaussian and an exponential decay respectively and can be described using Linear Response Theory. For stronger perturbations $F(t)$ decays algebraically as $F(t)\sim t^{-D_2}$, where $D_2$ is the correlation dimension of the critical eigenstates.Comment: 4 pages, 3 figures. Revised and published in Phys. Rev. Let

Sistem Deteksi Dini Penyakit Mulut dan Gigi dengan Metode Fuzzy Multi Criteria Decision Making

Gigi dan mulut adalah gerbang kesehatan tubuh. Gangguan gigi menjadi faktor risiko penyakit kronis seperti gagal ginjal, diabetes, dan gangguan jantung. Penyakit mulut dan gigi adalah penyakit tidak menular paling banyak yang diderita masyarakat. Layanan kesehatan gigi terbilang mahal, hal ini berdampak luas terhadap ekonomi dan membebani dana jaminan sosial. Sistem pakar adalah sebuah program yang mencoba menirukan proses pemikiran dan pengetahuan dari pakar-pakar dalam menyelesaikan masalah. Oleh karena itu, dibangunlah sebuah sistem yang memiliki pengetahuan seperti pakar gigi dan mulut untuk dapat melakukan diagnosa awal penyakit mulut dan gigi. Android tidak hanya platform smartphone paling popular di dunia, tetapi juga memiliki aplikasi terbanyak. Hal ini menjadi salah satu faktor pendukung pembangunan sistem ini dengan basis Android. Sistem ini dibangun menggunakan metode Fuzzy Multi Criteria Decision Making. Tingkat akurasi sistem dengan pakar dalam mendeteksi awal penyakit mulut dan gigi mencapai 71,67%

ANALISIS PERUBAHAN LUAS KAWASAN RESAPAN AIR DI KOTA MANADO

Pembangunan Kota Manado diarahkan ke lahan-lahan bertopografi berbukit yang berfungsi lindung sehingga banyak kawasan yang berubah fungsi menjadi kawasan pemukiman. Oleh sebab itu dilakukan penelitian yang bertujuan mengetahui sebaran kawasan resapan air dan kelas kesesuaiannya di Kota Manado serta untuk mengetahui luas perubahan kawasan resapan air periode tahun 2000-2012. Metode yang digunakan yaitu skoring dan overlay menggunakan sistem Informasi Geografi (SIG). Data-data yang digunakan yakni peta curah hujan, peta kemiringan lahan, peta eksisting penggunaan tahun 2000 dan tahun 2012, dan peta tekstur tanah. Hasil penelitian memperlihatkan Kota Manado pada tahun 2000 tidak ada kawasan yang memiliki  sebaran kawasan  resapan air dengan kelas sesuai. Kelas kesesuaian yang ada hanyalah kelas cukup sesuai, kelas kurang sesuai dan kelas tidak sesuai. Kelas kesesuaian kawasan resapan air tersebar di seluruh wilayah penelitian. Perubahan  luas kawasan resapan air di Kota Manado adalah sebagai berikut: (a) Kelas kesesuaian kurang sesuai mengalami perubahan penggunaan lahan seluas 967,45 Ha atau 22,87 % dari kawasan-kawasan yang terjadi alih fungsi lahan  atau sebesar 16,14 % dari seluruh luas kelas kurang sesuai; (b) Kelas kesesuaian cukup sesuai mengalami perubahan penggunaan lahan seluas 764,9 Ha atau 23,12% dari seluruh kelas cukup sesuai. Secara keseluruhan perubahan luas penggunaan lahan di kawasan resapan air Kota Manado periode tahun 2000-2012 baik kelas kesesuaian kurang sesuai maupun kelas kesesuaian cukup sesuai yakni sebesar 18,61% dari luas kawasan resapan air yakni seluas 9.307,87 Ha