379 research outputs found
DIS Structure Functions in Lattice QCD
In this talk I present the complete 1-loop perturbative computation of the
renormalization constants and mixing coefficients of quark and gluon lattice
operators of rank two and three whose hadronic elements enter in the
determination of the first and second moment of Deep Inelastic Scattering
Structure Functions, making use of the nearest-neighbor improved
``clover-leaf'' lattice QCD action.
To perform the huge amount of calculations required for the evaluation of all
the relevant Feynman diagrams, extensive use of symbolic manipulation languages
like Schoonschip and Form has been made.Comment: Talk presented at LATTICE96(theoretical developments) by S. Capitani;
3 pages, LaTeX and espcrc2.sty (included
Endoscopic vein harvesting Impact of learning curve on results and rehabilitation
Background: The tendency of modern surgery is towards the reduction of invasiveness. The aim of this study is to evaluate the impact of the learning curve, the reliability, the short term results and the advantages in terms of rapid rehabilitation of endoscopic vein harvesting (EVH) in a consecutive series of 20 patients operated on of aorto-coronary bypass surgery. Methods: Between February and June 2005, 20 patients between 61 e 82 years of age underwent EVH with the use of Vasoview® 5 (Guidant Corporation, Indianapolis, USA). To evaluate the impact of learning curve on the total operative time, patients were divided in 4 chronologically consecutive groups (G1, G2, G3, G4). Intraoperative characteristics and short term results were evaluated. Results: The mean velocity and the mean time of harvesting in G4 were 0,68 cm/min and 45 min. respectively, similar to the time required for a scheletonized left internal mammary artery harvesting. In the first 5 patients 2 conversions were required, one of them related to the EVH technique. No bleeding, functional impairment or infective complications are reported. Active mobilization was possible in every case in the first post-operative day. Conclusions: EVH is a reliable technique and the learning curve can be limited to the first 5 cases. The foreseeble reduction of infectious complications, the absence of pain and the immediate mobilization of the leg allow a rapid and effective rehabilitation
Deep Inelastic Scattering in Improved Lattice QCD. II. The second moment of structure functions
In this paper we present the 1-loop perturbative computation of the
renormalization constants and mixing coefficients of the lattice quark
operators of rank three whose hadronic elements enter in the determination of
the second moment of Deep Inelastic Scattering (DIS) structure functions.
We have employed in our calculations the nearest-neighbor improved
``clover-leaf'' lattice QCD action. The interest of using this action in Monte
Carlo simulations lies in the fact that all terms which in the continuum limit
are effectively of order ( being the lattice spacing) have been
demonstrated to be absent from on-shell hadronic lattice matrix elements. We
have limited our computations to the quenched case, in which quark operators do
not mix with gluon operators.
We have studied the transformation properties under the hypercubic group of
the operators up to the rank five (which are related to moments up to the
fourth of DIS structure functions), and we discuss the choice of the operators
considered in this paper together with the feasibility of lattice computations
for operators of higher ranks.
To perform the huge amount of calculations required for the evaluation of all
the relevant Feynman diagrams, we have extensively used the symbolic
manipulation languages Schoonschip and Form.Comment: 30 pages, latex + elsart + feynman (complete postscript file
available upon request to [email protected]); submitted to
Nuclear Physics
PDMS-based films containing surface-active amphiphilic block copolymers to combat fouling from barnacles B. amphitrite and B. improvisus
Surface-active amphiphilic diblock copolymers, Si-EFS14 and Si-EFS71, consisting of a poly(dimethyl siloxane) block (degree of polymerisation 11) and a poly(4-(triethyleneglycol monomethyl ether)-2,3,5,6-tetrafluorostyrene) block (average degree of polymerisation 14 and 71) were synthesised by ATRP. Films were prepared by incorporating each copolymer (4 wt%) into a PDMS matrix, which was then condensation cured. Bioassays were performed on the films using two barnacle species, Balanus amphitrite and Balanus improvisus, at different stages of their life cycles. The cyprids of B. improvisus settled on all test surfaces in higher numbers than those of B. amphitrite. However, the juveniles of B. improvisus were more easily removed from the films containing the copolymer Si-EFS14 than from those containing the copolymer Si-EFS71. An XPS analysis revealed that the near-surface region of copolymer Si-EFS71 was enriched in oxyethylenic chains and became even more populated by these hydrophilic chains after the films were immersed in water
Deep Inelastic Scattering in Improved Lattice QCD. I. The first moment of structure functions
We present the complete 1-loop perturbative computation of the
renormalization constants and mixing coefficients of the operators that measure
the first moment of deep inelastic scattering structure functions, employing
the nearest neighbor improved lattice QCD action. The interest of using this
action in Monte Carlo simulations lies in the fact that all terms which in the
continuum limit are effectively of order ( being the lattice spacing)
have been proven to be absent from on-shell hadronic lattice matrix elements.
Because of the complexity of the calculations, we have checked the analytical
expression of all Feynman diagrams using Schoonschip. To this end we have
developed a suitable code designed to automatically carry out all the necessary
lattice algebraic manipulations, starting from the elementary building blocks
of each diagram.
We have found discrepancies with some of the published numbers, but we are in
agreement with the known results on the energy-momentum tensor.Comment: 59 pages, plain LaTeX + Feynman.tex (complete postscript file
available upon request to [email protected]), Preprint Roma1
978-93 and ROM2F 93/38 (some numerical mistakes have been corrected in Sects.
2.2 and 8
Julolidine fluorescent molecular rotors as vapour sensing probes in polystyrene films
We introduce a new sensing polymer system for detection of volatile organic compounds (VOCs) based
on the optical response of polystyrene (PS) films doped with julolidine fluorescent molecular rotors
(FMRs). The julolidine FMRs exhibited viscosity-dependent changes in the fluorescence intensity, that
was enhanced when glycerol was added to ethanol solutions and when they were dispersed in PS films.
Thus, reduction in medium mobility slowed down internal motions and allowed for a major radiative
decay pathway. The FMR/PS films were exposed to several VOCs, and showed a significant decrease in
fluorescence emission when exposed to chloroform, whereas a negligible variation in their emission
occurred when methanol was utilized. This vapour sensing behaviour was much more evident when a
perfluorodecyl chain was linked to the julolidine core being the molecule segregated at the film surface.
This responsive behaviour was affected by solvent composition and its reproducible response was easily
determined by luminescence experiments
Evaluation of DNA typing as a positive identification method for soft and hard tissues immersed in strong acids
Amphiphilic modified-styrene copolymer films: Antifouling/fouling release properties against the green alga Ulva linza
Surface-active copolymers of a styrene carrying a polysiloxane side chain (SSi) and a triethyleneglycol monomethyl ether-modified pentafluorostyrene (EFS) (39 and 77 mol% EFS) were prepared and incorporated (8 wt% loading) into a polydimethyl siloxane (PDMS) matrix to produce crosslinked blend films. The wettability of the surface-active copolymer films and PDMS-blend films was investigated by contact angle measurements. An angle-resolved X-ray photoelectron spectroscopy (XPS) of the surface chemical composition before and after immersion in water for 7 days enabled location of the hydrophilic oxyethylenic segments of EFS within the top 10 nm from the film surface. Laboratory bioassays on the blend films against the marine green alga Ulva linza evidenced that the films containing the copolymer with the larger EFS content showed greater resistance to settlement of zoospores of U. linza, whereas both films had superior fouling-release properties of sporelings (young plants) compared to the PDMS standard films
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