1435 research outputs found
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Non-Abelian duality from vortex moduli: a dual model of color-confinement
No full textIt is argued that the dual transformation of non-Abelian monopoles occurring
in a system with gauge symmetry breaking G -> H is to be defined by setting the
low-energy H system in Higgs phase, so that the dual system is in confinement
phase. The transformation law of the monopoles follows from that of
monopole-vortex mixed configurations in the system (with a large hierarchy of
energy scales, v_1 >> v_2) G -> H -> 0, under an unbroken, exact color-flavor
diagonal symmetry H_{C+F} \sim {\tilde H}. The transformation property among
the regular monopoles characterized by \pi_2(G/H), follows from that among the
non-Abelian vortices with flux quantized according to \pi_1(H), via the
isomorphism \pi_1(G) \sim \pi_1(H) / \pi_2(G/H). Our idea is tested against the
concrete models -- softly-broken {\cal N}=2 supersymmetric SU(N), SO(N) and
USp(2N) theories, with appropriate number of flavors. The results obtained in
the semiclassical regime (at v_1 >> v_2 >> \Lambda) of these models are
consistent with those inferred from the fully quantum-mechanical low-energy
effective action of the systems (at v_1, v_2 \sim \Lambda)
Confining properties of QCD at finite temperature and density
No full textA disorder parameter detecting dual superconductivty of the vacuum is used as
a probe to characterize the confining properties of the phase diagram of two
color QCD at finite temperature and density. We obtain evidence for the
disappearing of dual superconductivity (deconfinement) induced by a finite
density of baryonic matter, as well as for a coincidence of this phenomenon
with the restoration of chiral symmetry both at zero and finite density. The
saturation transition induced by Pauli blocking is studied as well, and a
general warning is given about the possible effects that this unphysical
transition could have on the study of the QCD phase diagram at strong values of
the gauge coupling
A test of first order scaling in Nf=2 QCD
No full textWe complete our analysis of Nf=2 QCD based on the lattice staggered fermion
formulation. Using a series of Monte Carlo simulations at fixed (amq*Ls^yh) one
is able to test the universality class with given critical exponent yh. This
strategy has been used to test the O(4) universality class and it has been
presented at the previous Lattice conferences. No agreement was found with
simulations in the mass range amq=[0.01335,0.15] using lattices with Ls=16 up
to 32 and Lt=4. With the same strategy, we now investigate the possibility of a
first order transition using a new set of Monte Carlo data corresponding to
yh=3 in the same mass and volume range as the one used for O(4). A substantial
agreement is observed both in the specific heat scaling and in the scaling of
the chiral condensate, while the chiral susceptibilities still presents visible
deviation from scaling in the mass range explored
Separatrix chaos: new approach to the theoretical treatment
No full textSUMMARY We develop a new approach to the theoretical treatment of the separatrix
chaos, using a special analysis of the separatrix map. The approach allows us
to describe boundaries of the separatrix chaotic layer in the Poincar\'{e}
section and transport within the layer. We show that the maximum which the
width of the layer in energy takes as the perturbation frequency varies is much
larger than the perturbation amplitude, in contrast to predictions by earlier
theories suggesting that the maximum width is of the order of the amplitude.
The approach has also allowed us to develop the self-consistent theory of the
earlier discovered (PRL 90, 174101 (2003)) drastic facilitation of the onset of
global chaos between adjacent separatrices. Simulations agree with the theory
Confronto tra i test MAT ed ELISA indiretta impiegati nella diagnosi sierologica della leptospirosi da Leptospira hardjo in bovini e ovini
No full textRIASSUNTO Il presente studio ha messo a confronto i risultati ottenuti con la MAT e un kit ELISA indiretta presente in commercio, testando 103 sieri bovini e 91 ovini per la ricerca di anticorpi verso Leptospira interrogans serovar hardjo. Due sieri bovini, usati come controlli positivi, sono risultati positivi sia alla MAT che al test ELISA, mentre i rimanenti 101 campioni hanno fornito esito negativo con entrambi i test. Tra i sieri ovini i 10 impiegati come controlli negativi, sono risultati tali a MAT ed ELISA, i 3 controlli positivi hanno fornito risposte positive a entrambi i test. Tra i rimanenti 78 sieri ovini testati, 54 (69,23%) sono risultati positivi con la MAT a titoli anticorpali compresi tra 1:100 e 1:1600, mentre i rimanenti 24 (30,77%) hanno dato esito negativo. Con il test ELISA gli stessi sieri hanno fornito 60 (76,92%) risposte positive e 18 (23,08%) negative. Mettendo a confronto i risultati ottenuti, mediante MAT ed ELISA, con i 78 sieri di campo ovini il valore di concordanza tra i due test è risultato del 79,48%. Sebbene l’ELISA abbia fornito risultati soddisfacenti, potendo essa testare i sieri per una sola sierovariante alla volta, non può sostituirsi alla MAT che rimane il gold standard della diagnosi sierologica. SUMMARY The present study compared the results obtained by MAT and a commercial indirect ELISA kit testing 103 bovine and 91 ovine sera to detect antibodies against Leptospira interrogans serovar hardjo. Two bovine positive control resulted positive with MAT and ELISA, whereas the remaining 101 sera scored negative with both tests. Ten ovine negative and 3 positive controls resulted respectively negative and positive to both tests. Among the remaining 78 ovine sera, 24 (30.77%) scored MAT negative and 54 (69.23%) positive with antibody titres from 1:100 to 1:1600, whereas 18 (23.08%) resulted negative with ELISA and 60 (76.92%) positive. Comparing the results of MAT and ELISA, a concordance value of 79.48% was obtained. Even if ELISA gave satisfactory results, this test can not replace the MAT which represents the gold standard for the serological diagnosis
Valutazione nutrizionale del pisello proteico (Pisum sativum) in diete per ovini nutritive
No full textRIASSUNTO Il presente lavoro rientra in una linea di ricerca volta a valutare fonti proteiche alternative alla farina di estrazione di soia. A tale scopo è stata condotta una prova sperimentale per valutare appetibilità, digeribilità, bilancio azotato e valore nutritivo di diete a base di pisello proteico (Pisum sativum, var. Classic) nella specie ovina. Sono state formulate tre diete con una base foraggera comune (fieno polifita, PG: 11,0%, NDF: 59,6% sulla s.s.): due diete differivano per la diversa presenza di pisello (P23: percentuale di inclusione 23% e P48: 48%, sul t.q.) e per livello proteico (12,6% e 15,2% sulla s.s.) mentre la terza conteneva f. e. di soia (S: percentuale di inclusione 14% sul t.q.), quale fonte proteica di riferimento (PG: 14,5% sulla s.s.). Per questa prova sono stati impiegati 6 ovini adulti, maschi, castrati, di razza sarda, utilizzando un disegno sperimentale a quadrato latino 3 x 3 con due replicazioni. La digeribilità apparente, con le relative differenze significative (A,B: P<0,01), della sostanza organica è risultata pari a 69,7A% per P23, 76,2B% per P48 e 67,5A% per S, mentre quella delle proteine grezze, nello stesso ordine, 70,9%, 74,7% e 74,3%. Il bilancio dell’azoto è risultato positivo: 2,8 g/d per P23, 3,8 g/d per P48 e 3,8 g/d per S. Il valore nutritivo delle tre diete è risultato pari a 0,74A (F23), 0,83B (F48) e 0,71A (S) UFL/kg. I risultati ottenuti in questo studio indicano che il pisello proteico può rappresentare una valida alternativa alla farina di estrazione di soia nell’alimentazione degli ovini. SUMMARY The aim of the present work was to evaluate palatability, apparent digestibility, nitrogen balance and nutritive value of diets based on different level of pea seeds (Pisum sativum var. Classic) comparing to soybean meal. Six Sarda breed wethers were used in a two replicated 3 x 3 Latin Square design. Animals were fed three periods with three experimental diets. Diets were formulated on the basis of natural meadow hay (CP: 11,0%, NDF: 59,6% on DM basis). Two diets contained different levels of pea seeds: 23% (P23) and 48% (P48) as fed, with a crude protein content of 12.6% and 15.2% (on dry matter basis) respectively. The third, used as reference diet, was based on soybean meal (S), as protein source, with a crude protein content of 14.5%. Apparent digestibility values and statistical differences (A,B: P<0.01) for OM were: 69.7A% (P23), 76.2B% (P48) and 67.5A% (S), for crude protein: 70.9% (P23), 74.7% (P48) and 74.3% (S). A positive nitrogen balance was observed with the following values: 2.8 g/d (F20), 3.8 g/d (F38) and 3.8 g/d (S). Nutritive value of diets was: 0,74A (F20), 0,83B (F38) and 0,71A (S) French Milk Feed Unit/kg. Results showed that pea seeds can be utilized to replace soybean meal in sheep
Tutela dell’incolumità pubblica dall’aggressività dei cani. Nota 2. L’ordinanza 12 dicembre 2006
No full textRIASSUNTO Gli Autori prendono in considerazione e commentano gli articoli dell’Ordinanza 12 dicembre 2006, Tutela dell’incolumità pubblica dall’aggressione di cani, emanata dal Ministro della salute Livia Turco e concludono che tale problema non può essere affrontato con lo strumento giuridico dell’Ordinanza, provvedimento privo di qualsiasi effetto sanzionatorio e provvisorio in attesa di una legge definitiva. L’Ordinanza ripropone una lista di 17 razze di cani per i quali si impone in ogni luogo pubblico l’obbligo dell’uso contestuale del guinzaglio e della museruola; l’obbligo da parte di chi possiede tali cani e non è in grado di mantenerli nel rispetto delle disposizioni dell’Ordinanza, di interessare le autorità veterinarie competenti del territorio al fine di ricercare con le amministrazioni comunali idonee soluzioni di gestione dell’animale; il divieto di amputare ai cani coda e orecchie per motivi estetici; l’obbligo per i proprietari di razze pericolose di stipulare una polizza assicurativa di responsabilità per i danni alle persone; il divieto di interventi chirurgici che non siano giustificati dalla salvaguardia della salute dell’animale per tutti i tipi di cani; il divieto di addestramenti tesi ad aumentare l’aggressività degli “amici dell’uomo” e l’utilizzo di collari elettrici. SUMMARY The authors take in consideration and comment the articles of the Ordinance (December, 12 2006) emanated by the minister of the public health (Livia Turco) regarding the guardianship from dog assaults. The Ordinance lists 17 breeds of dogs for which is obliged the contextual use of leash and muzzle when these dogs are conducted in public areas. The Ordinance force the owners of this 17 breeds to stipulate an insurance for the potential damages to people. Anyone who possesses such kind of dogs and is not able to keep it in respect to the dispositions of the Ordinance, can leave his dog to the veterinary service, competent of the territory. The veterinary service, consequently, must find a management solution for the animal with the municipal administrations. In addition Ordinance forbid the dog training (carried out with the aim to increase the aggressiveness), the use of the shock collars, the cut of the dog tails and the surgical interventions to the ears (for aesthetic reasons not justified by the safeguard of the health of the animal). The authors conclude that the matter must be ruled by the parliament through a low, since it is not possible to give solutions to such problems though the instrument of the Ordinance, which is temporary and do not penalise the defaulters
Sul detto comune: il sapere è pubblico in teoria, ma privato nella pratica
No full textRIASSUNTO Come è possibile conciliare l'esigenza teorica della condivisione, essenziale per la scienza, con quella pratica della selezione? Occorre ripensare il peer review in rete, rendendolo retroattivo e aperto. SUMMARY How is it possible, in the communication of science, to accommodate sharing with selection? Open access publishing gives us the opportunity to try new peer review styles, as for instance open peer review and retroactive peer review
Color-coding algorithms to the balanced path problem: computational issues
No full textGiven a weighted directed network G, we
consider the problem of computing k balanced paths from given
source nodes to given destination nodes of G,
i.e., k paths such that the difference in cost between the longest and the
shortest path is minimized.
Although not yet investigated by the OR scientific community, except
for some preliminary theoretical results concerning the special case of acyclic
networks, balanced path problems arise in several
interesting applications, both in transportation and in
telecommunication settings. For example, in load balancing of multiple Quality of Service (QoS) paths in the IP
Telephony service, the problem of minimizing the end-to-end delay
difference between the longest and the shortest path in multiple
path management schemes has been suggested in the literature as a promising line of
research.
In this work the focus is on the computation of
node-disjoint balanced paths in the general
case, where the input graph
G may have any structure.
Starting from some algorithmic ideas proposed
for acyclic networks, a general framework
is firstly described, which is based on the color-coding method for computing
simple paths. Then the general framework is specialized and a pool of algorithms is designed which includes both
an exact approach as well as
alternative heuristics. The algorithms have been tested
on a large suite of instances generated from
some benchmark telecommunication instances.
The obtained computational
results are very interesting: in some cases, the exact
color-coding algorithm produces the optimal solution very rapidly; in
the remaining cases, some of the proposed
heuristics are able to generate high quality solutions in a very
quick time
A Comparative Study of Tree Generative Kernels for Gene Function Prediction
No full textIn this report we perform a comparative study of kernel functions defined on generative models with the goal to embed phylogenetic information into a discriminative learning approach. We describe three generative tree kernels: a sufficient statistics kernel, a Fisher kernel, and a probability product kernel; their key features are the adaptivity to the input domain and the ability to deal with structured data. In particular, kernel adaptivity is obtained through the estimation of the parameters of a tree structured model of evolution from an input domain of phylogenetic profiles encoding the presence or absence of specific proteins in a set of fully sequenced genomes. We report results obtained in the prediction of the functional class of the proteins of the yeast S. Cervisae together with comparisons with a standard vector based kernel and with a non-adaptive tree kernel function. To further analyze the impact of the discriminative learning phase, and to provide an assessment of the information retained by the learned generative models we apply them directly to classification through log-odds. Finally, the advantage achieved through adaptivity for two of the new kernels is assessed through a comparison with similar kernels based on randomly initialized generative models where no learning is performed, and to kernels where parameters are set only on the base of biological considerations