The n-body problem in General Relativity up to the second post-Newtonian order from perturbative field theory

Motivated by experimental probes of general relativity, we adopt methods from perturbative (quantum) field theory to compute, up to certain integrals, the effective lagrangian for its n-body problem. Perturbation theory is performed about a background Minkowski spacetime to O[(v/c)^4] beyond Newtonian gravity, where v is the typical speed of these n particles in their center of energy frame. For the specific case of the 2 body problem, the major efforts underway to measure gravitational waves produced by in-spiraling compact astrophysical binaries require their gravitational interactions to be computed beyond the currently known O[(v/c)^7]. We argue that such higher order post-Newtonian calculations must be automated for these field theoretic methods to be applied successfully to achieve this goal. In view of this, we outline an algorithm that would in principle generate the relevant Feynman diagrams to an arbitrary order in v/c and take steps to develop the necessary software. The Feynman diagrams contributing to the n-body effective action at O[(v/c)^6] beyond Newton are derived.Comment: 39 pages. The Mathematica code used in this paper can be found at http://www.stargazing.net/yizen/PN.html Version 2: Slight re-wording of section on removal of accelerations in 2 PN lagrangian; comments added in conclusion; and typographical errors fixed. Article is similar to that published in PR

Exploiting Third Language Production Corpora for Pedagogical Purposes

Investigating bilingual learners’ learning third language (L3) can be a daunting task for teachers, in the extent of individual differences. However, by documenting learners’ L3 production in a corpus file format, certain analysis can be imparted more easily to examine every possible aspect that is at play during learning process. More specifically, when having a big size of natural speech data, teachers will have loads of empirical evidence of their learners’ language to conduct a variety of scientific exploration on stages of language development, the argument we borrow from O’Keeffe, McCarthy and Carter (2007). A corpus of this kind is particularly useful for teachers in developing teaching-oriented corpora and for learners in having a direct contact to the corpus data or so-called ‘data-driven learning’ (Timmis, 2015). Our current paper, therefore, focuses on the exploitation of a learner corpus in the teaching and learning of third language in Indonesian context. Our corpus was built within the seven months of the main author’s dissertation fieldwork conducted to the 261 students of grade 3 of six primary schools in East Java that has enriched the previous limited corpus of CBLING (Corpus of Bilingual Language). Collected through a variety of experimental tasks, these corpora compiled the English and Javanese L3 written production. The findings suggest that our learner corpora can be exploited for pedagogical purposes such as to provide learners with primary linguistic resources and authentic materials, to supply teachers with empirical evidence of common language errors and interlanguage performance as to enable them to monitor learners’ L3 acquisition and development, to help teachers construct a more relevant lesson plan, to evaluate existing teaching materials, and so forth. In this way, we aim at promoting an innovative teaching and learning through ‘big data’ exploitation. In the realm of individual differences, the investigation of bilingual learners learning the third language (L3) can be a daunting task for teachers. However, by documenting their L3 production, an analysis that examines every possible aspect that is at play during the learning process can be conducted more easily. More specifically, when having a big size of natural speech data, teachers will have bundles of evidence of their learners’ acquisition necessary to conduct scientific exploration on stages of language development. This is the argument borrowed from McCarthy and O’Keeffe (2010) who refer to the extensive use of CHILDES Language Database as first language research resources dating back as early as the 1960s. A corpus of this kind is especially useful for teachers in developing teaching-oriented corpora and for learners in having a direct contact with the corpus data or so-called ‘data-driven learning’. In this study, our corpus was built during a seven-month dissertation fieldwork involving 261 students of Grade 3 of six Primary Schools in East Java. It compiled the English and Javanese L3 written production of all six schools and the English and Javanese L3 spoken production of two schools collected through a variety of experimental tasks. The findings suggest that learner corpora can be exploited for pedagogical practices such as to provide learners with primary linguistic resources and authentic materials, to supply teachers with empirical evidence of common language errors and interlanguage performance as to enable them to monitor learners’ L3 acquisition and development, and to help teachers construct a more relevant lesson plan. This way, we aim to not only promote an innovative teaching and learning through a ‘big data’ exploitation but also elevate the interface of research and practice.     Keywords: learner corpora, L3 production, pedagogical practice

Uji Bioaktivitas Ekstrak Padina Australis Dari Pesisir Pantai Molas Sulawesi Utara Terhadap Bakteri Staphylococcus Epidermidis

Penelitian ini bertujuan untuk mengetahui bioaktivitas ekstrak P. australis terhadap bakteri S. epidermidis. Metode yang digunakan dalam uji bioaktivitas adalah uji Minimum Inhibitory Concentration (MIC) dan uji Minimum Bactericidal Concentration (MBC). Pengujian bioaktivitas dilakukan dengan menggunakan Rancangan Acak Lengkap (RAL) dengan 5 perlakuan yaitu seri konsentrasi ekstrak 30%, 60%, 90%, kontrol negatif (CMC 1%) dan kontrol positif (cotrimoksazole). Penentuan nilai MIC dengan analisis kekeruhan menggunakan spektrofotometer (ƛ630 nm) sedangkan nilai MBC dengan metode pour plate. Data hasil uji MBC dianalisis menggunakan ANOVA one way kemudian dilanjutkan dengan Uji Tukey. Hasil penelitian ini menunjukkan nilai MIC (Kadar Hambat Minimal) adalah konsentrasi 90%. Hasil analisa statistika ANOVA one way data uji MBC menunjukkan terdapat perbedaan yang signifikan antara pemberian ekstrak dengan total koloni yang tumbuh pada media NA. Uji Tukey menunjukkan bahwa ekstrak P. australis yang menunjukkan bioaktivitas terbaik terhadap S. epidermidis adalah konsentrasi 90% dengan selisih 631 koloni dengan konsentrasi 60% dan 658 koloni dengan konsentrasi 30%. Total koloni yang tumbuh pada media NA dengan perlakuan konsentrasi ekstrak 90% adalah 31 koloni. Ekstrak etanol Padina australis memiliki bioaktivitas dalam menghambat pertumbuhan bakteri S. epidermidis. Nilai MIC ekstrak P. australis terhadap bakteri S. epidermidis adalah konsentrasi 90%. Nilai MBC tidak diketahui dikarenakan pada pengujian lanjut (MBC) konsentrasi yang menunjukkan nilai MIC merupakan konsentrasi tertinggi yaitu 90% masih ditemukan koloni bakteri yang tumbuh pada media N

A bolometric measurement of the antineutrino mass

High statistics calorimetric measurements of the beta spectrum of 187Re are being performed with arrays of silver perrhenate crystals operated at low temperature. After a modification of the experimental set-up, which allowed to substantially reduce the background of spurious counts and therefore to increase the sensitivity on the electron antineutrino mass, a new measurement with 10 silver perrhenate microbolometers is running since July 2002. The crystals have masses between 250 and 350 micrograms and their average FWHM energy resolution, constantly monitored by means of fluorescence X-rays, is of 28.3 eV at the beta end-point. The Kurie plot collected during 4485 hours x mg effective running time has an end-point energy of 2466.1 +/- 0.8{stat} +/- 1.5 {syst} eV, while the half lifetime of the decay is found to be 43.2 +/- 0.2{stat} +/- 0.1{syst} Gy. These values are the most precise obtained so far for 187Re. From the fit of the Kurie plot we can deduce a value for the squared electron antineutrino mass m(nu)^2 of 147 +/- 237{stat} +/- 90{syst} eV^2. The corresponding 90% C.L. upper limit for m(nu) is 21.7 eV.Comment: 3 pages, 3 figures. Submitted to Phys. Rev. Let

BPS Domain Walls and Vacuum Structure of N=1 Supergravity Coupled to a Chiral Multiplet

We study BPS domain walls of N=1 supergravity coupled to a chiral multiplet and their Lorentz invariant vacua which can be viewed as critical points of BPS equations and the scalar potential. Supersymmetry further implies that gradient flows of BPS equations controlled by a holomorphic superpotential and the Kaehler geometry are unstable near local maximum of the scalar potential, whereas they are stable around local minimum and saddles of the scalar potential. However, the analysis using RG flows shows that such gradient flows do not always exist particularly in infrared region.Comment: 17 pages, a typo corrected in section

Some Aspects of Spherical Symmetric Extremal Dyonic Black Holes in 4d N=1 Supergravity

In this paper we study several aspects of extremal spherical symmetric black hole solutions of four dimensional N=1 supergravity coupled to vector and chiral multiplets with the scalar potential turned on. In the asymptotic region the complex scalars are fixed and regular which can be viewed as the critical points of the black hole and the scalar potentials with vanishing scalar charges. It follows that the asymptotic geometries are of a constant and non-zero scalar curvature which are generally not Einstein. These spaces could also correspond to the near horizon geometries which are the product spaces of a two anti-de Sitter surface and the two sphere if the value of the scalars in both regions coincides. In addition, we prove the local existence of non-trivial radius dependent complex scalar fields which interpolate between the horizon and the asymptotic region. We finally give some simple {\lC}^{n}-models with both linear superpotential and gauge couplings.Comment: 17 pages, no figure. Added an author. Major revision: typos and grammar corrected, some statements modified, added a section about local existence of scalar fields. Accepted for publication in Int J Mod Phys

Soliton-like Solution on the Dynamics of Modified Peyrard-Bishop DNA Model in the Thermostat as a Bio-Fluid

The Peyrard-Bishop (PB) DNA model is the most representative model to investigate DNA dynamics because the model is able to answer DNA denaturation processes even though the model has restricted review that DNA assumes without surrounding interaction. In this study, we investigate the dynamics of the modified PB DNA model by considering DNA in the Nosé-Hoover thermostat as a bio-fluid with various viscosities. Viscosity variations are reviewed through temperature variations, namely thermal viscosity. We attain the dynamical equation of DNA in the form of a nonlinear Schrödinger-like (NLS-like) equation by using the perturbation method and continuous approximation. We solve the NLS-like equations by the numerical split-step Fourier method. We obtain a soliton-like solution for the dynamics of this specific DNA model. The behavior of the soliton-like solution fluctuates as the temperature increases, representing the fluctuational openings of DNA, i.e., denaturation bubbles. In addition, that behavior also evolves with variations of the perturbation parameter. Moreover, we obtain soliton-like solutions by balancing the perturbation and the nonlinearity of the DNA system from the bio-fluid interaction. Furthermore, for the specific thermal viscosity of bio-fluid, we gain the denaturation temperature at 370 K ≤ T ≤ 380 K. Doi: 10.28991/ESJ-2022-06-04-01 Full Text: PD