1,372 research outputs found
On symplectic semifield spreads of PG(5,q2), q odd
We prove that there exist exactly three non-equivalent symplectic semifield spreads of PG ( 5 , q2), for q2> 2 .38odd, whose associated semifield has center containing Fq. Equivalently, we classify, up to isotopy, commutative semifields of order q6, for q2> 2 .38odd, with middle nucleus containing q2Fq2and center containing q Fq
Technological activities of Staphylococcus carnosus and Staphylococcus simulans strains isolated from fermented sausages
The aim of this study was to determine the technological properties of 2 strains of Staphylococcus simulans (Ssm12, Ssm21) and 4 strains of S. carnosus (SC28, SC31, SC54 and SC55) for the selection of a potential starter cultures to employ in the processing of dry fermented sausages. The strains were studied to evaluate nitrate reductase, proteolytic, lipolytic, decarboxylase and antioxidant activities as well as growth ability at different temperatures, pH and NaCl concentrations. Nitrate reductase activity was determined at 15, 20 and 30 degrees C. By spectrophotometric method all the strains were able to reduce nitrate to nitrite at the different temperatures but these results were not confirmed by the agar plate method. Antioxidant and lipolytic activities were evaluated by spectrophotometric assay. All the strains showed antioxidative enzymes superoxide dismutase (SOD) and catalase whereas all appeared unable to hydrolyse pork fat. Proteolytic activity was determined by agar plate method, spectrophotometric assay (OPA) and sodium dodecyl sulphate gel-electrophoresis (SDS-PAGE) and all strains appeared to be able to hydrolyse sarcoplasmic proteins but not myofibrillar proteins. Finally, all the strains grew at 15 and 20 degrees C, in presence of 10%, 15% and 20% of NaCl and at pH 5.0 and 5.5 and were unable to produce histamine, cadaverine and putrescine. The results showed that all strains studied possess useful technological activities that would make them eligible as a good starter cultures for fermented sausages
Phase Transitions in Gauge Models: Towards Quantum Simulations of the Schwinger-Weyl QED
We study the ground-state properties of a class of lattice
gauge theories in 1 + 1 dimensions, in which the gauge fields are coupled to
spinless fermionic matter. These models, stemming from discrete representations
of the Weyl commutator for the group, preserve the unitary
character of the minimal coupling, and have therefore the property of formally
approximating lattice quantum electrodynamics in one spatial dimension in the
large- limit. The numerical study of such approximated theories is important
to determine their effectiveness in reproducing the main features and
phenomenology of the target theory, in view of implementations of cold-atom
quantum simulators of QED. In this paper we study the cases by
means of a DMRG code that exactly implements Gauss' law. We perform a careful
scaling analysis, and show that, in absence of a background field, all
models exhibit a phase transition which falls in the Ising
universality class, with spontaneous symmetry breaking of the symmetry. We
then perform the large- limit and find that the asymptotic values of the
critical parameters approach the ones obtained for the known phase transition
the zero-charge sector of the massive Schwinger model, which occurs at negative
mass.Comment: 15 pages, 18 figure
Selection of Lactobacillus strains from fermented sausages for their potential use as probiotics.
A rapid screening method was used to isolate potentially probiotic Lactobacillus strains from fermented sausages after enrichment in MRS broth at pH 2.5 followed by bile salt stressing (1% bile salts w/v). One hundred and fifty acid- and bile-resistant strains were selected, avoiding preliminary and time-consuming isolation steps. Strains were further characterized for survival at pH 2.5 for 3 h in phosphate-buffered saline and for growth in the presence of 0.3% bile salts with and without pre-exposure at low pH. Twentyeight strains showed a survival >80% at pH 2.5 for 3 h; moreover, most of the strains were able to grow in the presence of 0.3% bile salts. Low pH and bile resistance was shown to be dependent on both the species, identified by phenotypic and molecular methods, and the strain tested. This is the first report on the direct selection of potentially probiotic lactobacilli from dry fermented sausages. Technologically interesting strains may be used in the future as probiotic starter cultures for novel fermented sausage manufacture
Discrete Abelian Gauge Theories for Quantum Simulations of QED
We study a lattice gauge theory in Wilson's Hamiltonian formalism. In view of
the realization of a quantum simulator for QED in one dimension, we introduce
an Abelian model with a discrete gauge symmetry , approximating
the theory for large . We analyze the role of the finiteness of the
gauge fields and the properties of physical states, that satisfy a generalized
Gauss's law. We finally discuss a possible implementation strategy, that
involves an effective dynamics in physical space.Comment: 13 pages, 3 figure
Short communication: Identification and technological characterization of yeast strains isolated from samples of water buffalo Mozzarella cheese
Abstract Sixty yeast cultures were isolated from samples of water buffalo Mozzarella, a popular "pasta filata" cheese, originating on 16 farms located in the provinces of Salerno, Caserta, and Frosinone (Italy). Strains were identified by means of 5.8S internal transcribed spacer rDNA PCR-RFLP combined with 26S rRNA gene partial sequencing and characterized for their ability to exert biochemical properties of technological interest. The recorded dominance of fermenting yeasts such as the lactose-fermenting Kluyveromyces marxianus (38.3% of the total isolates) and the galactose-fermenting Saccharomyces cerevisiae (21.6% of the total isolates) suggests that these yeasts contribute to the organoleptic definition of the water buffalo Mozzarella. The speciographic analysis revealed the presence of 7 other species rarely or never reported in a dairy environment belonging to the genera Pichia and Candida , whose role in Mozzarella cheese organoleptic properties need to be further investigated
Satellite SAR Interferometry for Earth’s Crust Deformation Monitoring and Geological Phenomena Analysis
Synthetic aperture radar interferometry (InSAR) and the related processing techniques provide a unique tool for the quantitative measurement of the Earth’s surface deformation associated with certain geophysical processes (such as volcanic eruptions, landslides and earthquakes), thus making possible long-term monitoring of surface deformation and analysis of relevant geodynamic phenomena. This chapter provides an application-oriented perspective on the spaceborne InSAR technology with emphasis on subsequent geophysical investigations. First, the fundamentals of radar interferometry and differential interferometry, as well as error sources, are briefly introduced. Emphasis is then placed on the realistic simulation of the underlying geophysics processes, thus offering an unfolded perspective on both analytical and numerical approaches for modeling deformation sources. Finally, various experimental investigations conducted by acquiring SAR multitemporal observations on areas subject to deformation processes of particular geological interest are presented and discussed
On the maximum field of linearity of linear sets
Let denote an -dimensional -vector space. For an
-dimensional -subspace of assume that for each
non zero vector . If then we prove the existence of an
integer such that the set of one-dimensional
-subspaces generated by non-zero vectors of is the same
as the set of one-dimensional -subspaces generated by
non-zero vectors of . If we view as a
point set of , it means that and determine the same set of directions. We prove a
stronger statement when .
In terms of linear sets it means that an -linear set of
has maximum field of linearity only if it
has a point of weight one. We also present some consequences regarding the size
of a linear set
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