311 research outputs found
SU(2) Glueballs, diquarks and mesons in dense matter
We present preliminary results from a high statistics study of 2-color QCD at
low temperature and non-zero baryon density. The simulations are carried out on
a 6^3*12 lattice and use a standard hybrid molecular dynamics algorithm for
staggered fermions for two values of quark mass. Observables include glueball
correlators evaluated via a multi-step smearing procedure as well as scalar and
vector mesons and diquarks.Comment: Poster presented at Lattice 2003 (Non zero temperature and density),
3 pages, 4 figure
Glueballs and mesons in the superfluid phase of two-color QCD
QCD with two colors undergoes a transition to a superfluid phase with diquark
condensate when the quark chemical potential equals half the pion mass. We
investigate the gluonic aspects of the transition by inspecting the behavior of
the glueball correlators evaluated via a multi-step smearing procedure for
several values of chemical potential ranging between zero and the saturation
threshold. The results are based on an analysis of 0++ glueball correlators, on
a sample of 40000 independent configurations on each parameter set. The
amplitudes of the correlators peak for \mu = m_\pi/2,indicating that the
superfluid phase transition affects the gluonic sector as well. The mass of the
fundamental state decreases in the superfluid phase, and the amplitude of the
propagators drops, suggesting a reduction of the gluon condensate, in agreement
with model calculations. The analysis of the smearing dependence of the results
helps disentangling the role of long and short distance phenomena at the
superfluid transition.Comment: 7 pages, 5 figures, talk presented at the XXV International Symposium
on Lattice Field Theory, July 30 - August 4, 2007, Regensburg,German
Supplemental LED increases tomato yield in mediterranean semi-closed greenhouse
Supplemental light (SL) is a technique used to increase horticulture yield, especially in northern countries, where the Daily Light Integral (DLI) is a limiting factor during fall and winter, and which could also be used to obtain higher tomato yield at the mediterranean latitude. In this study, three tomato hybrid (F1) cultivars were grown for year-round production in a commercial semi-closed glasshouse in Southern Italy: two of the cherry fruit-type (‘Juanita’ and ‘Sorentyno’) and one mini plum fruit-type (‘Solarino’). From 120 to 243 days after transplant, light-emitting diode (LED) toplights were used as SL, with a photoperiod of 18 h. The main climatic parameters inside and outside the glasshouse were recorded, and tomato plants’ development and yield were examined. Plants grown with LEDs had longer stems as compared to control treatment (9.53 vs. 8.79 m), a higher stem thickness and yielded more trusses. On average, the yield was 21.7% higher with LEDs. ‘Sorentyno’ was the cultivar with the highest cumulated productivity when it was grown under SL. However, the cultivar with best light use efficiency under LEDs was ‘Solarino’. Therefore, supplemental LED from mid-December until march enhanced tomato growth and yield, opening a favorable scenario for large-scale application of this technology also in the mediterranean area
Lattice Gauge Fixing for Parameter Dependent Covariant Gauges
We propose a non-perturbative procedure to fix generic covariant gauges on
the lattice. Varying the gauge parameter, this gauge fixing provides a concrete
method to check numerically the gauge dependence of correlators measured on the
lattice. The new algorithm turns out to converge with a good efficiency. As a
preliminary physical result, we find a sensitive dependence of the gluon
propagator on the gauge parameter.Comment: 10 pages (LaTeX2e), 5 eps figure
Lattice Renormalization of Quark Operators
We have technically improved the non-perturbative renormalization method,
proposed by Martinelli et al., by using quark momentum sources and sinks.
Composite two-fermion operators up to three derivatives have been measured for
Wilson fermions and Sheikholeslami-Wohlert improved fermions in the quenched
approximation. The calculations are performed in the Landau gauge on 16^3x32
lattices at beta = 6.0 for 3 kappa values in each case. The improved sources
greatly decrease the statistical noise. We extract and discuss here
renormalization factors for local operators and moments of the structure
functions for Wilson fermions.Comment: 3 pages, Latex, 6 figures. epsf.sty and espcrc2.sty needed. Talk
given at Lattice9
Histological and immunohistochemical characterisation of uterine adenocarcinoma in an Asian elephant (Elephas Maximus)
A 56-year-old nulliparous female Asian elephant (Elephas maximus) living at the zoological garden of Naples (Italy), with a clinical history of recurrent colic, was found in agonal state and humane euthanasia was elected. At necropsy the uterine body was moderately increased in size and the lumen was reduced due to a poorly demarcated and infiltrative neoplasm. Furthermore, multiple, whitish, firm nodules were present in both lungs. Histological examination of the uterinemass revealed epithelial cells arranged in tubular or solid pattern infiltrating the endometrium and the muscular layer. Immunohistochemical examination showed immunoreactivity of neoplastic cells to oestrogen receptors antibody. Pulmonary lesions were histologically and immunohistochemically superimposable to the epithelial uterine neoplasm. A definitive diagnosis of uterine adenocarcinoma with pulmonary metastases was made
Non-perturbative quark mass renormalization
We show that the renormalization factor relating the renormalization group
invariant quark masses to the bare quark masses computed in lattice QCD can be
determined non-perturbatively. The calculation is based on an extension of a
finite-size technique previously employed to compute the running coupling in
quenched QCD. As a by-product we obtain the --parameter in this theory
with completely controlled errors.Comment: Talk given at LATTICE '97, 6 pages, Latex source, 7 eps figures,
needs epsfi
Mature teratoma arising from an undescended testis in a horse: comparison between ultrasonographic and morphological features
Scant information is available on the ultrasonographic appearance of different testicular tumours in the stallion. Preoperative ultrasound imaging and gross and microscopic features of a testicular teratoma in a horse is described. An asymptomatic 4 years old cryptorchid Arabian horse was admitted for orchiectomy. Combined transabdominal and inguinal ultrasound examination revealed a large complex ovoid mass, containing both solid and cystic elements with internal echoes, located dorsally to the superficial inguinal ring. Two main hypoechoic cavities divided by a linear hyperechoic septum were evident, with a hyperechoic circular structure inside the lumen of the largest one. A tumour of the undescended testis was suspected. Ultrasound findings guided a provisional diagnosis of teratoma that was confirmed by histology following surgical removal of the tumour. Due to the correspondence between ultrasonographic and morphological features, trans-abdominal ultrasonography was conclusive in the preoperative planning
Non-perturbative Renormalisation of Domain Wall Fermions: Quark Bilinears
We find the renormalisation coefficients of the quark field and the flavour
non-singlet fermion bilinear operators for the domain wall fermion action, in
the regularisation independent (RI) renormalisation scheme. Our results are
from a quenched simulation, on a 16^3x32 lattice, with beta=6.0 and an extent
in the fifth dimension of 16. We also discuss the expected effects of the
residual chiral symmetry breaking inherent in a domain wall fermion simulation
with a finite fifth dimension, and study the evidence for both explicit and
spontaneous chiral symmetry breaking effects in our numerical results. We find
that the relations between different renormalisation factors predicted by
chiral symmetry are, to a good approximation, satisfied by our results and that
systematic effects due to the (low energy) spontaneous chiral symmetry breaking
and zero-modes can be controlled. Our results are compared against the
perturbative predictions for both their absolute value and renormalisation
scale dependence.Comment: 53 pages, 21 figures, revte
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