Matrice nad nekomutativnim prstenima

Tema ovog radu su matrice nad nekomutativnim prstenom. U prvom i drugom poglavlju pod nazivom Prsteni i Moduli uvodimo osnovne pojmove koji su nam potrebni u daljnjem dijelu rada. Pojam poluprostota, kojim se bavimo u trećem poglavlju, je najosnovniji termin koji se proteze kroz čitav diplomski rad. Prezentiramo tri definicije poluprostog modula i dokazujemo da su one ekvivalentne. Pomoću navedenih uvjeta možemo dokazati Jacobsonov teorem o gustoći te definirati pojmove poluprostog i prostog prstena. Uz Jacobsonov teorem u radu dokazujemo i druge važne teoreme, kao primjer Wedderburnov teorem koji nam daje prikaz prstena R kao D-endomorfizam nad modulom E, gdje sa D označavamo konačnodimenzionalnu algebru sa dijeljenjem nad poljem k.The theme of this paper are matrices over noncommutative ring. In the first and second chapter titled Rings and Modules we introduce the basic concepts that are required in the far part of the work. The concept semisimplicity, the main theme of the third chapter, is the most basic term that runs through this entire graduate paper. We present three definitions of semisimple modules and prove that they are equivalent. Besides Jacobson’s theorem we also prove some others very important theorems, for example Wedderbun’s theorem which gives us a representation of a ring R as the ring of D-endomorphisms of module E, where D is a finite-dimensional division algebra over a field k. Using the above conditions we can prove Jacobson’s density theorem and define the terms of semisimple and simple ring

Monitoramento da higiene de têxteis usados na indústria de alimentos

Protective clothing is required in the food-processing industry, to protect workers from contamination by bacteria, fungi, viruses, prions etc. contained in the secretions and raw meat of slaughtered animals, and to protect the meat from being contaminated by microorganisms carried by the workers. It is well-understood that textiles are a control point (CP), and must be appropriately cleaned and disinfected in order to prevent biocontamination. Although the laundering procedure itself is important for achieving disinfection, it is also essential to maintain an appropriate hygiene level in the laundry, in order to prevent recontamination of textiles by environmental viable microorganisms. In this study, a sanitary-microbiologicalanalysis was carried out in selected CPs in two laundries. Chemo-thermal washing efficiency was determined by evaluating the anti-bacterial effect against Enterococcus faecium and Staphylococcus aureus. The hygienic state of the laundries was determined by evaluating the number and type of microorganisms at selected CPs throughout the whole laundering procedure. The results indicated that the sanitary condition of both laundries did not reach the required levels and that several microbes were resistant to cleaning and disinfecting agents. It is obvious from the results that achievement of an appropriate hygiene level during laundering textiles from the food processing industry requires the implementation of appropriate corrective monitoring measures.Na indústria de alimentos é necessário o uso de roupas de proteção, para proteger os trabalhadores da contaminação por bactérias, fungos, virus, prions, etc, encontrados nas secreções e carne dos animais abatidos, assim como proteger a carne da contaminação com microrganismos carreados pelos trabalhadores. Os têxteis são um Ponto de Controle (PC), e devem ser limpos e desinfetados de forma adequada para prevenir a biocontaminação. Embora o processo de lavagem seja importante para obter a desinfecção, é também essencial manter um nível apropriado de higiene dentro da lavanderia para prevenir recontaminação dos têxteis com microrganismos do ambiente. Nesse trabalho, realizou-se uma análise microbiológica de Pontos Críticos de duas lavanderias. A eficiência da lavagem termoquímica foi determinada através da análise do efeito antibacteriano contra Enterococcus faecium e Staphylococcus aureus. A higiene nas lavanderias foi avaliada através da determinação do número e tipos de microrganismos presentes em PCs selecionados no processo de lavagem. Os resultados indicaram que as condições de higiene nas duas lavanderias não atingiram os níveis necessários, e que vários microrganismos apresentaram resistência aos agentes sanificantes e de limpeza, indicando a necessidade de implementação de medidas corretivas apropriadas

Non-equilibrium simulations of thermally induced electric fields in water.

Using non-equilibrium molecular dynamics simulations, it has been recently demonstrated that water molecules align in response to an imposed temperature gradient, resulting in an effective electric field. Here, we investigate how thermally induced fields depend on the underlying treatment of long-ranged interactions. For the short-ranged Wolf method and Ewald summation, we find the peak strength of the field to range between 2 × 10(7) and 5 × 10(7) V/m for a temperature gradient of 5.2 K/Å. Our value for the Wolf method is therefore an order of magnitude lower than the literature value [J. A. Armstrong and F. Bresme, J. Chem. Phys. 139, 014504 (2013); J. Armstrong et al., J. Chem. Phys. 143, 036101 (2015)]. We show that this discrepancy can be traced back to the use of an incorrect kernel in the calculation of the electrostatic field. More seriously, we find that the Wolf method fails to predict correct molecular orientations, resulting in dipole densities with opposite sign to those computed using Ewald summation. By considering two different multipole expansions, we show that, for inhomogeneous polarisations, the quadrupole contribution can be significant and even outweigh the dipole contribution to the field. Finally, we propose a more accurate way of calculating the electrostatic potential and the field. In particular, we show that averaging the microscopic field analytically to obtain the macroscopic Maxwell field reduces the error bars by up to an order of magnitude. As a consequence, the simulation times required to reach a given statistical accuracy decrease by up to two orders of magnitude.Engineering and Physical Sciences Research Council (Grant ID: EP/I001352/1)This is the author accepted manuscript. The final version is available from the American Institute of Physics via http://dx.doi.org/10.1063/1.495303

Antimicrobial Effect of Probiotics against Common Pathogens

The antimicrobial or antagonistic activity of probiotics is an important property that includes the production of antimicrobial compounds, competitive exclusion of pathogens, enhancement of the intestinal barrier function and others. There are many methods to ascertain probiotic properties, including various in vitro and in vivo methods. The in vivo methods include various modifications of the spot‐on lawn assay, agar well diffusion assay (AWDA), co‐culturing methods, usage of cell lines and others. In many cases in vitro antagonist activity is observed, but in real settings it is not observed. The in vivo methods mainly used are animal models; however, their use is being restricted according to the European legislation OJ L136. The justification of animal models is also questionable as the results of studies on animals do not predict the same results for humans. The use of replacement alternative methods, for example incorporating human cells and tissues, avoids such confounding variables. Most important studies are double‐blinded randomized clinical trials; however, these studies are difficult to perform as it is not easy to achieve uniform conditions. There is a clear need for more elaborate assays that would better represent the complex interactions between the probiotics and the final host. This complex situation is a challenge for scientists

The characterisation of the “X” crystal structure in the Stillinger-Weber potential

A recently observed crystal structure is characterised by reference to the calculated diffraction patterns. The “X” crystal is related to the β-Sn crystal structure via an atom displacement and a reduction in symmetry from tetragonal to orthorhombic. A further crystal polymorph is identified which retains the tetragonal symmetry of the β-Sn structure but involves a related atom displacement. The unit cells and space groups are reported. The two crystals are labelled as o-X and t-X respectively. The transformation mechanisms from the β-Sn crystal structure to the two structures are identified. No routes to these crystals from other polymorphs are found

Liquid state anomalies and the relationship to the crystalline phase diagram

A relationship between the observation of a density anomaly and the underlying crystalline phase diagram is demonstrated. The crystal phase diagram and temperature of maximum density (TMD) lines are calculated over a range of parameter space using a Stillinger-Weber potential. Relationships between the loci of density maxima in the P T plane for the liquid state and the underlying crystalline phase diagram are investigated. Two key potential parameters are systematically varied in order to control the balance between the model two- and three-body interaction terms, and the relative effects of varying the potential parameters analyzed. The respective TMD lines diverge at extreme values with one set of lines showing a reentrant behavior. For each parameter set the TMD lines are extrapolated to T = 0 K. The corresponding pressures are related to the crystalline phase diagram and are found to lie on or near specific crystal-crystal coexistence lines for a wide range of potential parameters. The density anomaly is observed to vanish corresponding to regions in the crystal phase diagram which lack crystalcrystal coexistence lines potentially offering a new interpretation for the emergence of anomalous behavior

Thermodynamic anomalies, polyamorphism and all that

The appearance and evolution of thermodynamics anomalies, and related properties, are studied for two classes of system, modelling those dominated by covalent and ionic interactions, respectively. Such anomalies are most familiar in the density but are also present in other thermodynamics variables such as the compressibility and heat capacity. By systematically varying key model parameters the emergence and evolution of these anomalies can be tracked across the phase space. The interaction of the anomalies can often be rationalized by thermodynamics ‘rules’. The emergence of these anomalies may also be correlated with the appearance of polyamorphism, the existence of multiple amorphous states which differ in density and entropy