Self-similarity and scaling behavior of scale-free gravitational clustering

We measure the scaling properties of the probability distribution of the smoothed density field in $N$-body simulations of expanding universes with scale-free initial power-spectra, with particular attention to the predictions of the stable clustering hypothesis. We concentrate our analysis on the ratios $S_Q(\ell)\equiv {\bar \xi}_Q/{\bar \xi}_2^{Q-1}$, $Q \leq 5$, where ${\bar \xi}_Q$ is the averaged $Q$-body correlation function over a cell of radius $\ell$. The behavior of the higher order correlations is studied through that of the void probability distribution function. As functions of ${\bar \xi}_2$, the quantities $S_Q$, $3 \leq Q \leq 5$, exhibit two plateaus separated by a smooth transition around ${\bar \xi}_2 \sim 1$. In the weakly nonlinear regime, {\bar \xi}_2 \la 1, the results are in reasonable agreement with the predictions of perturbation theory. In the nonlinear regime, ${\bar \xi}_2 > 1$, the function $S_Q({\bar \xi}_2)$ is larger than in the weakly nonlinear regime, and increasingly so with $-n$. It is well-fitted by the expression $S_Q= ({\bar \xi}_2/100)^{0.045(Q-2)}\ {\widetilde S}_Q$for all$n. This weak dependence on scale proves {\em a small, but significant departure from the stable clustering predictions} at least for n=0$and$n=+1$. The analysis of$P_0$confirms that the expected scale-invariance of the functions$S_Q$is not exactly attained in the part of the nonlinear regime we probe, except possibly for$n=-2$and marginally for$n=-1$. In these two cases, our measurements are not accurate enough to be discriminant.Comment: 31 pages, postscript file, figure 1 missing. Postscript file including figure 1 available at ftp://ftp-astro-theory.fnal.gov:/pub/Publications/Pub-95-256-

Extended Perturbation Theory for the Local Density Distribution Function

Perturbation theory makes it possible to calculate the probability distribution function (PDF) of the large scale density field in the small variance limit. For top hat smoothing and scale-free Gaussian initial fluctuations, the result depends only on the linear variance, sigma_linear, and its logarithmic derivative with respect to the filtering scale -(n_linear+3)=dlog sigma_linear^2/dlog L (Bernardeau 1994). In this paper, we measure the PDF and its low-order moments in scale-free simulations evolved well into the nonlinear regime and compare the results with the above predictions, assuming that the spectral index and the variance are adjustable parameters, n_eff and sigma_eff=sigma, where sigma is the true, nonlinear variance. With these additional degrees of freedom, results from perturbation theory provide a good fit of the PDFs, even in the highly nonlinear regime. The value of n_eff is of course equal to n_linear when sigma << 1, and it decreases with increasing sigma. A nearly flat plateau is reached when sigma >> 1. In this regime, the difference between n_eff and n_linear increases when n_linear decreases. For initial power-spectra with n_linear=-2,-1,0,+1, we find n_eff ~ -9,-3,-1,-0.5 when sigma^2 ~ 100.Comment: 13 pages, 6 figures, Latex (MN format), submitted to MNRA

Die gute alte Fruchtfolge als Bekämpfungsmethode gegen den Maiswurzelbohrer (Diabrotica virgifera virgifera LeConte)

Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae), the western corn rootworm (WCR), is an immigrant from North America and one of the top ten global agricultural pest species. Within the last 15 years, WCR invaded Europe at 3 focal points, and has been steadily extending its domain soon threatening commercial maize production. After the first detection in Switzerland in 2000 near Lugano, careful observations by pheromone trap monitoring of this quarantine organism have been realized. Experiences with WCR whose populations dynamics are incompletely understood, have also been studied by installing a continuous maize field comparing population dynamics with rotated maize fields in the immediate surroundings. Our experiences with WCR populations in the Swiss territory are here briefly summarized: 1. Mandatory crop rotation in the canton Ticino slowed spread of WCR significantly. WCR infestations north of the main Alpine mountain chain were rare and eradicated by crop rotation. 2. In a continuous maize cropping system population of WCR can reach economic damage level, but can also be confined by unknown factors 3. Switzerland with its rigorous crop rotation program may serve as an example of farsighted WCR management preserving environment and saving money

Collective migration and patterning during early development of zebrafish posterior lateral line

The morphogenesis of zebrafish posterior lateral line (PLL) is a good predictive model largely used in biology to study cell coordinated reorganization and collective migration regulating pathologies and human embryonic processes. PLL development involves the formation of a placode formed by epithelial cells with mesenchymal characteristics which migrates within the animal myoseptum while cyclically assembling and depositing rosette-like clusters (progenitors of neuromast structures). The overall process mainly relies on the activity of specific diffusive chemicals, which trigger collective directional migration and patterning. Cell proliferation and cascade of phenotypic transitions play a fundamental role as well. The investigation on the mechanisms regulating such a complex morphogenesis has become a research topic, in the last decades, also for the mathematical community. In this respect, we present a multiscale hybrid model integrating a discrete approach for the cellular level and a continuous description for the molecular scale. The resulting numerical simulations are then able to reproduce both the evolution of wild-type (i.e. normal) embryos and the pathological behaviour resulting form experimental manipulations involving laser ablation. A qualitative analysis of the dependence of these model outcomes from cell-cell mutual interactions, cell chemical sensitivity and internalization rates is included. The aim is first to validate the model, as well as the estimated parameter values, and then to predict what happens in situations not tested yet experimentally. This article is part of the theme issue 'Multi-scale analysis and modelling of collective migration in biological systems'

A comparison of estimators for the two-point correlation function

Nine of the most important estimators known for the two-point correlation function are compared using a predetermined, rigorous criterion. The indicators were extracted from over 500 subsamples of the Virgo Hubble Volume simulation cluster catalog. The ``real'' correlation function was determined from the full survey in a 3000Mpc/h periodic cube. The estimators were ranked by the cumulative probability of returning a value within a certain tolerance of the real correlation function. This criterion takes into account bias and variance, and it is independent of the possibly non-Gaussian nature of the error statistics. As a result for astrophysical applications a clear recommendation has emerged: the Landy & Szalay (1993) estimator, in its original or grid version Szapudi & Szalay (1998), are preferred in comparison to the other indicators examined, with a performance almost indistinguishable from the Hamilton (1993) estimator.Comment: aastex, 10 pages, 1 table, 1 figure, revised version, accepted in ApJ

PERLINDUNGAN KONSUMEN TERHADAP MAKANAN JAJANAN YANG MENGANDUNG FORMALIN DAN BORAKS(SUATU PENELITIAN DI KOTA BANDA ACEH)

ABSTRAKNANDA MAULINA SAFIRA,PERLINDUNGAN KONSUMEN TERHADAP 2014MAKANAN JAJANAN YANG MENGANDUNG FORMALIN DAN BORAKS (Studi Penelitian di Kota Banda Aceh)Fakultas Hukum Universitas Syiah Kuala(iv, 63) pp., tabl., bibl., appdx.( RISMAWATI, S.H., M.Hum. )Dalam Pasal 4 huruf a Undang-Undang Perlindungan Konsumen dijelaskan bahwa konsumen memiliki hak atas keselamatan dalam mengkonsumsi barang. Dalam Pasal 67 Undang-Undang Nomor 18 Tahun 2012 tentang Pangan dijelaskan bahwa ketentuan keamanan pangan diselenggarakan untuk menjaga pangan tetap aman dikonsumsi, sehingga terhindar dari kemungkinan cemaran biologis atau kimia yang dapat membahayakan kesehatan manusia. Dalam Peraturan Menteri Kesehatan Nomor 33 Tahun 2012 tentang Bahan Tambahan Pangan disebutkan bahwa bahan yang dilarang digunakan sebagai bahan tambahan pangan diantaranya adalah formalin dan boraks. Pada kenyataannya, di Kota Banda Aceh terdapat masalah dalam mewujudkan perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks.Penulisan skripsi ini bertujuan untuk menjelaskan perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks, faktor penyebab tidak berjalannya perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks, dan upaya mengatasi hambatan perwujudan perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks.Data yang diperlukan dalam tulisan ini adalah data sekunder dan data primer. Data sekunder diperoleh melalui penelitian kepustakaan dilakukan dengan cara membaca peraturan perundang-undangan, buku-buku, surat kabar dan bahan-bahan lain yang berkaitan dengan penelitian ini, dan data primer diperoleh dengan cara mewancarai responden dan informan.Hasil penelitian menunjukkan bahwa perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks di Kota Banda Aceh, belum berjalan sebagaimana yang telah diatur dalam Undang-Undang Nomor 18 Tahun 2012 dan Peraturan Menteri Kesehatan Nomor 33 Tahun 2012. Faktor penyebab tidak berjalannya perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks yaitu kurangnya sosialisasi peraturan perundang-undangan, kurangnya pengawasan, kurangnya ketegasan dalam penerapan sanksi dan kurangnya laporan dari pihak masyarakat.Upaya mengatasi hambatan perwujudan perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks yaitu penyuluhan hukum, pengawasan, peringatan dan pembinaan.Disarankan kepada instansi pemerintahan seperti Dinas Kesehatan dan BBPOM untuk menambah jumlah petugas serta mengalokasikan dana dalam melakukan pemeriksaan dan pengujian makanan jajanan sehingga terselenggaranya perlindungan konsumen terhadap makanan jajanan yang mengandung formalin dan boraks.Banda Ace

Hyperextended Cosmological Perturbation Theory: Predicting Non-linear Clustering Amplitudes

We consider the long-standing problem of predicting the hierarchical clustering amplitudes $S_p$ in the strongly non-linear regime of gravitational evolution. N-body results for the non-linear evolution of the bispectrum (the Fourier transform of the three-point density correlation function) suggest a physically motivated ansatz that yields the strongly non-linear behavior of the skewness, $S_3$, starting from leading-order perturbation theory. When generalized to higher-order ($p>3$) polyspectra or correlation functions, this ansatz leads to a good description of non-linear amplitudes in the strongly non-linear regime for both scale-free and cold dark matter models. Furthermore, these results allow us to provide a general fitting formula for the non-linear evolution of the bispectrum that interpolates between the weakly and strongly non-linear regimes, analogous to previous expressions for the power spectrum.Comment: 20 pages, 6 figures. Final version accepted by ApJ. Includes new paragraphs on factorizable hierarchical models and agreement of HEPT with the excursion set model for white-noise Gaussian fluctuation

Production of high purity 52g^{52g}Mn from nat^{nat}V targets with α\alpha-beams at cyclotrons

Radioisotope $^{52g}$Mn is of special interest for multimodal imaging. Using state-of-art nuclear reaction codes, we study the alternative nuclear reaction route $^{nat}$V($\alpha$,x)$^{52g}$Mn in comparison with the standard production routes based upon the use of chromium targets. The integral yields of $^{52g}$Mn and contaminants have been evaluated. The main outcome of this investigation is that the production of the main contaminant isotope $^{54}$Mn is expected to be lower than with $^{nat}$Cr. The study also reveals a large spread in the cross-section data set and points out the need of more precise measurements of the reaction $^{nat}$V($\alpha$,x)$^{52g}$Mn as well as the need of a more accurate theoretical description.Comment: Keywords: Cyclotron radionuclide production, $^{52g}$Mn, $^{53}$Mn, $^{54}$Mn, multi-modal imaging,{\alpha}-induced reactions, nuclear reactions modelin