Search results for "ATZ"
showing 10 items of 256 documents
Charmed and Bottom Baryons: a Variational Approach based on Heavy Quark Symmetry
2003
The use of Heavy Quark Symmetry to study bottom and charmed baryons leads to important simplifications of the non-relativistic three body problem, which turns out to be easily solved by a simple variational ansatz. Our simple scheme reproduces previous results (baryon masses, charge and mass radii, $...$) obtained by solving the Faddeev equations with simple non-relativistic quark--quark potentials, adjusted to the light and heavy--light meson spectra. Wave functions, parameterized in a simple manner, are also given and thus they can be easily used to compute further observables. Our method has been also used to find the predictions for strangeness-less baryons of the SU(2) chirally inspire…
Spherical multiquark states in the chiral bag model
1984
Abstract We study n-quark systems (n = 3, 6, 12) in the chiral bag model. In order to handle the non-linearities of the model, the hedgehog ansatz for the Goldstone pion field is used. It is found that due to “warping” of the quark orbits in the presence of mean-field pion clouds, a strong repulsion is developed when more than three quarks are put in a bag. This repulsion mechanism turns out to be close to the soliton mechanism discovered by Skyrme two decades ago. Even the magnitude of the repulsion agrees with his. It is also possible to relate the repulsion to the effective quenching of the axial charge of the multiquark system and a suggestion is made that the recently observed quenchin…
Reliģisko svētku statuss Latvijā
2020
Maģistra darbā „Reliģisko svētku statuss Latvijā” ir pētīti jautājumi, kas saistās ar svētku dienu tiesisko regulējumu atbilstoši normatīvo aktu prasībām. Maģistra darba mērķis ir izvērtēt spēkā esošo regulējumu par svētku, atceres un atzīmējamajām dienām. Lai sasniegtu mērķi ir nepieciešams izvērtēt svētku dienu tiesisko regulējumu no valsts pirmās neatkarības laika līdz mūsdienām un salīdzināt svētku dienu tiesisko regulējumu citās valstīs. Pētījuma rezultātā iegūtā informācija ļaus labāk izprast un izanalizēt iespējamos grozījumus likumā „Par svētku, atceres un atzīmējamām dienām”. Tēma šobrīd ir īpaši aktuāla, ņemot vērā to, ka kopš 1990. gada katras Saeimas deputāti iesniedz identiskus…
Nepārtikas produktu tirgus uzraudzība Eiropas Savienībā
2018
Efektīva tirgus uzraudzība ir būtiska ne tikai sabiedrības interešu un drošības aizsardzībai un godīgas konkurences nodrošināšanai, bet arī ES Vienotā tirgus pilnvērtīgai funkcionēšanai produktu jomā – lai netiktu kavēta atbilstošu produktu aprite, tajā pašā laikā tiktu mērķtiecīgi identificēti neatbilstoši produkti un par tiem atbildīgie komersanti. Maģistra darbā ir analizēta ES tirgus uzraudzības sistēma nepārtikas produktu jomā - izvērtējot tiesību ietvaru, labo praksi efektīvā uzraudzībā, un novērtējot tirgus uzraudzības rezultātus, kā arī ir noteikti būtiskākie izaicinājumi un piedāvāti nepieciešamie uzlabojumi tirgus uzraudzības sistēmas pilnveidošanai. Maģistra darba rezultāti ir ap…
Alcuni indici per la valutazione dei sistemi di controllo per l’illuminazione
2018
Gli edifici smart hanno visto negli ultimi anni una sempre più ampia diffusione. Per questo motivo ricercatori, progettisti e tecnici, hanno posto una crescente attenzione sull’utilizzo di sistemi di controllo automatici per l’illuminazione. Questa tipologia di sistemi gioca, infatti, un ruolo chiave nel raggiungimento di significativi riduzioni dei consumi elettrici e dei benefici legati all’utilizzo della luce naturale (ad esempio il comfort visivo degli occupanti, il benessere e la produttività). È prassi comune, durante la fase progettuale, correlare il risparmio energetico con la disponibilità della luce diurna, poiché risulta un obiettivo rilevante per progettisti e architetti.
Benedetto XVI e il compito urgente dell’educazione
2015
All’origine della riflessione sull’urgenza di una Nuova Evangelizzazione ci sta la constatazione di una diffusa situazione di crisi di valori cristiani e educativi, percepibili soprattutto nei Paesi di antica cristianità. Più volte, nei suoi discorsi, Benedetto XVI concentra l’attenzione sulla necessità di educazione: in primo luogo dei genitori «preoccupati e spesso angosciati per il futuro dei loro figli» degli insegnanti «che vivono la triste esperienza del degrado delle scuole» e della società stessa «che vede messe in dubbio dalla crisi dell’educazione le basi stesse della convivenza». Si evidenzia la necessità dell’educazione principalmente per le nuove generazioni. Ma la percezione d…
Accelerated mineralisation of atrazine in maize rhizosphere soil
2002
International audience; The mineralisation rate of atrazine measured in soil pre-treated with this herbicide, was significantly higher in the maize rhizosphere than in bulk soil. Maize rhizosphere was also shown to significantly increase microbial biomass C as compared with bulk soil. Ribosomal intergenic spacer analysis conducted on nucleic acids extracted directly from soil samples revealed that the structure of microbial communities observed in the rhizosphere was slightly different from that of bulk soil. The quantification of the relative amount of the gene atzC, which encodes an enzyme involved in atrazine mineralisation, was carried out on soil nucleic acids by using quantitative-com…
Solution of XXZ and XYZ spin chains with boundaries by separation of variables
2014
In this thesis we give accounts on the solution of the open XXZ and XYZ quantum spin-1/2 chains with the most generic integrable boundary terms. By using the the Separation of Variables method (SoV), due to Sklyanin, we are able, in the inhomogeneous case, to build the complete set of eigenstates and the associated eigenvalues. The characterization of these quantities is made through a maximal system of N quadratic equations, where N is the size of the chain. Different methods, like the Algebraic Bethe ansatz (ABA) or other generalized Bethe ansatz techniques, have been used, in the past, in order to tackle these problems. None of them resulted effective in the reproduction of the full set …
One-dimensional random walks with self-blocking immigration
2017
We consider a system of independent one-dimensional random walkers where new particles are added at the origin at fixed rate whenever there is no older particle present at the origin. A Poisson ansatz leads to a semi-linear lattice heat equation and predicts that starting from the empty configuration the total number of particles grows as $c \sqrt{t} \log t$. We confirm this prediction and also describe the asymptotic macroscopic profile of the particle configuration.
A form factor approach to the asymptotic behavior of correlation functions in critical models
2011
We propose a form factor approach for the computation of the large distance asymptotic behavior of correlation functions in quantum critical (integrable) models. In the large distance regime we reduce the summation over all excited states to one over the particle/hole excitations lying on the Fermi surface in the thermodynamic limit. We compute these sums, over the so-called critical form factors, exactly. Thus we obtain the leading large distance behavior of each oscillating harmonic of the correlation function asymptotic expansion, including the corresponding amplitudes. Our method is applicable to a wide variety of integrable models and yields precisely the results stemming from the Lutt…