Airflow Resistance of Wheat Bedding as Influenced by the Filling Method

A study was conducted to estimate the degree of variability of the airflow resistance in wheat caused by the filling method, compaction of the sample, and airflow direction. Two types of grain chambers were used: a cylindrical column 0.95 m high and 0.196 m in diameter, and a cubical box of 0.35 m side. All factors examined were found to influence considerably the airflow resistance. Gravitational axial filling of the grain column from three heights (0.0, 0.95 and 1.8 m) resulted in the pressure drops of 1.0, 1.3, and 1.5 kPa at the airflow velocity of 0.3 m/s. Consolidation of axially filled samples by vibration resulted in a maximum 2.2 times increase in airflow resistance. The tests with cubical sample showed that in axially filled samples the pressure drop in vertical direction was maximum 1.5 times higher than in horizontal directions. In the case of asymmetrically filled samples, the pressure drop at the airflow velocity of 0.3 m/s in vertical direction Z was found to be 1.3 of that in horizontal direction X and 1.95 times higher than with horizontal direction Y, perpendicular to X. Variations in airflow resistance in values comparable to that found in the present project may be expected in practice

Analysis of fungal air pollution using different samplers

The aim of this study was the analysis of fungal air pollution in different rooms using different the air samplers. Air for mycological studies was collected from various hospital rooms. To monitor fungal air pollution were used samplers: SAS SUPER 100 (pbi-international), MAS 100 (Merck) and AIR IDEAL (BioMerieux). We found differences in CFU/L values in depending on hospital room and the air sampler type. The CFU/L values of air samples taken by the AIR IDEAL ranged from 350 to 850 and (724.2 ± 159.9), and the CFU/L values of air samples taken by the sampler SAS SUPER 100 ranged from 160 to 800 (455.3 ± 250.73). The CFU/L values of air samples taken by the MAS 100 sampler varied from 50 to 1340 (302.5±56.6) From the air samples of both samplers was incubated 6 genera/species of fungi. Candia albicans fungi species and genus Penicillium species were most frequently isolated from SAS Super 100 sampler, and Penicillium species from the AIR IDEAL sampler. From the air samples of MAS 100 was isolated 11 types/species of fungi and in air samples of SAS Super 100 was isolated 7 types/species. Significant differences of CFU/L values in the tested rooms were found in depending on the used sampler. Mycological analysis of the obtained cultures from air samples suggests that there is not same isolation of fungi using the different samplers

Colored Spin Systems, BKP Evolution and finite N_c effects

Even within the framework of the leading logarithmic approximation the eigenvalues of the BKP kernel for states of more than three reggeized gluons are unknown in general, contrary to the planar limit case where the problem becomes integrable. We consider a 4-gluon kernel for a finite number of colors and define some simple toy models for the configuration space dynamics, which are directly solvable with group theoretical methods. Then we study the dependence of the spectrum of these models with respect to the number of colors and make comparisons with the large limit case.Comment: 17 pages, 4 figures, references update, to appear on EPJ

Reggeon exchange from gauge/gravity duality

We perform the analysis of quark-antiquark Reggeon exchange in meson-meson scattering, in the framework of the gauge/gravity correspondence in a confining background. On the gauge theory side, Reggeon exchange is described as quark-antiquark exchange in the t channel between fast projectiles. The corresponding amplitude is represented in terms of Wilson loops running along the trajectories of the constituent quarks and antiquarks. The paths of the exchanged fermions are integrated over, while the "spectator" fermions are dealt with in an eikonal approximation. On the gravity side, we follow a previously proposed approach, and we evaluate the Wilson-loop expectation value by making use of gauge/gravity duality for a generic confining gauge theory. The amplitude is obtained in a saddle-point approximation through the determination near the confining horizon of a Euclidean "minimal surface with floating boundaries", i.e., by fixing the trajectories of the exchanged quark and antiquark by means of a minimisation procedure, which involves both area and length terms. After discussing, as a warm-up exercise, a simpler problem on a plane involving a soap film with floating boundaries, we solve the variational problem relevant to Reggeon exchange, in which the basic geometry is that of a helicoid. A compact expression for the Reggeon-exchange amplitude, including the effects of a small fermion mass, is then obtained through analytic continuation from Euclidean to Minkowski space-time. We find in particular a linear Regge trajectory, corresponding to a Regge-pole singularity supplemented by a logarithmic cut induced by the non-zero quark mass. The analytic continuation leads also to companion contributions, corresponding to the convolution of the same Reggeon-exchange amplitude with multiple elastic rescattering interactions between the colliding mesons.Comment: 60+1 pages, 14 figure

The spin dependence of high energy proton scattering

Motivated by the need for an absolute polarimeter to determine the beam polarization for the forthcoming RHIC spin program, we study the spin dependence of the proton-proton elastic scattering amplitudes at high energy and small momentum transfer.We examine experimental evidence for the existence of an asymptotic part of the helicity-flip amplitude phi_5 which is not negligible relative to the largely imaginary average non-flip amplitude phi_+. We discuss theoretical estimates of r_5, essentially the ratio of phi_5 to phi_+, based upon extrapolation of low and medium energy Regge phenomenological results to high energies, models based on a hybrid of perturbative QCD and non-relativistic quark models, and models based on eikonalization techniques. We also apply the model-independent methods of analyticity and unitarity.The preponderence of evidence at available energy indicates that r_5 is small, probably less than 10%. The best available experimental limit comes from Fermilab E704:those data indicate that |r_5|<15%. These bounds are important because rigorous methods allow much larger values. In contradiction to a widely-held prejudice that r_5 decreases with energy, general principles allow it to grow as fast as ln(s) asymptotically, and some models show an even faster growth in the RHIC range. One needs a more precise measurement of r_5 or to bound it to be smaller than 5% in order to use the classical Coulomb-nuclear interference technique for RHIC polarimetry. As part of this study, we demonstrate the surprising result that proton-proton elastic scattering is self-analysing, in the sense that all the helicity amplitudes can, in principle, be determined experimentally at small momentum transfer without a knowledge of the magnitude of the beam and target polarization

Instantons and the infrared behavior of the fermion propagator in the Schwinger Model

Fermion propagator of the Schwinger Model is revisited from the point of view of its infrared behavior. The values of anomalous dimensions are found in arbitrary covariant gauge and in all contributing instanton sectors. In the case of a gauge invariant, but path dependent propagator, the exponential dependence, instead of power law one, is established for the special case when the path is a straight line. The leading behavior is almost identical in any sector, differing only by the slowly varying, algebraic prefactors. The other kind of the gauge invariant function, which is the amplitude of the dressed Dirac fermions, may be reduced, by the appropriate choice of the dressing, to the gauge variant one, if Landau gauge is imposed.Comment: 9 pages, in REVTE

Rekurencyjna eliminacja cech z walidacją oraz relaksacja liniowej separowalności jako metody selekcji cech do analizy zbiorów danych zawierających wartości ekspresji genów

Most of the commonly known feature selection methods focus on selecting appropriate predictors for image recognition or generally on data mining issues. In this paper we present a comparison between widely used Recursive Feature Elimination (RFE) with resampling method and the Relaxed Linear Separability (RLS) approach with application to the analysis of the data sets resulting from gene expression experiments. Different types of classification algorithms such as K-Nearest Neighbours (KNN), Support Vector Machines (SVM) and Random Forests (RF) are exploited and compared in terms of classification accuracy with optimal set of genes treated as predictors selected by either the RFE or the RLS approaches. Ten-fold cross-validation was used to determine classification accuracy.Zdecydowana większość znanych metod selekcji cech skupia się na wyborze odpowiednich predyktorów dla takich zagadnień jak rozpoznawanie obrazów czy też ogólnie eksploracji danych. W publikacji prezentujemy porównanie pomiędzy powszechnie stosowaną ˛metodą˛ Rekurencyjnej Eliminacji Cech z walidacja˛ (ang. Recursive Feature Elimination - RFE) a metodą stosującą ˛podejście Relaksacji Liniowej Separowalności (ang. Relaxed Linear Separability - RLS) z zastosowaniem do analizy zbiorów danych zawierających wartości ekspresji genów. W artykule wykorzystano różne algorytmy klasyfikacji, takie jak K-Najbliższych Sąsiadów (ang. K-Nearest Neighbours - KNN), Maszynę˛ Wektorów Wspierających (ang. Support Vector Machines - SVM) oraz Lasy Losowe (ang. Random Forests -RF). Porównana została jakość klasyfikacji uzyskana przy pomocy tych algorytmów z optymalnym zestawem cech wygenerowanym z wykorzystaniem metody selekcji cech RFE bądź RLS. W celu wyznaczenia jakości klasyfikacji wykorzystano 10-krotną walidację˛ krzyżową