8,040 research outputs found
Baryonic masses based on the NJL model
We employ the Nambu Jona--Lasinio model to determine the vacuum pressure on
the quarks in a baryon and hence their density inside. Then we estimate the
baryonic masses by implementing the local density approximation for the mean
field quark energies obtained in a uniform and isotropic system. We obtain a
fair agreement with the experimental masses.Comment: 17 pages, 3 figures. to be published on EPJ
Are there hadronic bound states above the QCD transition temperature?
Recent lattice QCD calculations, at physical pion masses and small lattice
spacings that approach the continuum limit, have revealed that non-diagonal
quark correlators above the critical temperature are finite up to about 2
. Since the transition from hadronic to free partonic degrees of freedom
is merely an analytic cross-over, it is likely that, in the temperature regime
between 1-2 , quark and gluon quasiparticles and pre-hadronic bound states
can coexist. The correlator values, in comparison to PNJL model calculations
beyond mean-field, indicate that at least part of the mixed phase resides in
color-neutral bound states. A similar effect was postulated for the in-medium
fragmentation process, i.e. for partons which do not thermalize with the system
and thus constitute the non-equilibrium component of the particle emission
spectrum from a deconfined plasma phase. Here, for the first time we
investigate the likelihood of forming bound states also in the equilibrated,
parton dominated phase above which is described by lattice QCD.Comment: 15 pages, 4 Figure
Combining Lightness and Stiffness through Composite-Reinforced Additive Manufacturing in the Yacht Industry: Case Study Analysis and Application on Large Functional Components
This paper explores applications of additive manufacturing (AM) for producing structural components in the yacht industry. Several case studies illustrate how AM is applied to create lightweight composite panels and complex geometries that are challenging to produce with traditional methods. Experimental and simulation studies demonstrate the mechanical performance of AM-produced parts. The key benefits demonstrated include design flexibility and zero-tool manufacturing. The potential roles of AM in addressing industry challenges, such as customisation possibilities and more sustainable production methods, are discussed. The case studies indicate the technical feasibility of 3D printing for functional yacht applications across various scales. Overall, AM shows promise in revolutionising design and manufacturing approaches by enabling optimised structures and on-demand production without traditional manufacturing constraints. This research study highlights the technology's role in evolving yacht design and production practices
GlobVolcano Project Overview
The GlobVolcano project is part of the ESA DUE
programme. The project aims at demonstrating EO-based
services to support the Volcanological Observatories and other
mandate users (e.g. Civil Protection authorities, scientific
communities of volcanoes) in their monitoring activities.
During the project a worldwide selection of user organizations
will cooperate with the GlobVolcano team in order to harmonize
user’s requirements and to evaluate the EO-based services . The
“Osservatorio Vesuviano” of Naples (INGV-Italy) coordinates
the communications between the project and the User
Community. IPGP of Paris is responsible for the scientific
coordination and the validation activities.
The project activities are split in two phases. During the first
phase (completed in June 2008) the service infrastructure and
interface to the users have been developed. Prototype EO-based
information products have been generated and validated. Service
provision on pre-operational basis will take place during the
second phase
Radiological evaluation of the metal-bone interface of a porous tantalum acetabular component
Introduction Porous tantalum presents a bone-matched elastic modulus and an high coefficient of friction on cancellous and cortical bone. Furthermore, its open-cell tantalum structure of repeating dodecahedrons, similar to cancellous bone, should be favourable for bone ingrowth. These physical and mechanical properties should increase primary fixation and potential osteointegration of acetabular cups and should decrease periacetabular stress shielding. The purpose of this study was to radiographically evaluate the evolution of the metal-bone interface of porous tantalum acetabular components.
Materials and Methods Serial radiographic evaluation of 41porous tantalum acetabular component has been performed in 40 patients. Twelve hips underwent total hip arthroplasty using a trabecular metal monoblock acetabular component and 29 hips using a trabecular metal modular acetabular system. All patients were clinically and radiographically evaluated at four, eight, 12, 24 weeks, 12 months and then annually. All cases were available for a minimum follow-up of two years (mean 35 months). On post-operative x-rays the metal-bone interface was investigated for areas in which the porous surface of the acetabular component was not in contact with bone. These gaps were measured and classified by
location according to DeLee and Charnley zones. Evolution of postoperative gaps, presence of lysis or periacetabular radiolucencies and component migration were assessed during follow-up.
Results On post-operative x-rays 36 components (88%) had a gap between the outer surface and the host bone but only in 12 cases (29%) gaps were larger then 1 mm. The gaps were mostly situated in the polar region (zone II) when compared with the peripheral zones and no one was bigger then 5 mm in width. At last follow-up 23 (64%) of the initial gaps were no longer radiographically evident, 10 (28%) had a favourable evolution and appeared reduced in dimension but still present and 3 (8%) didn\u2019t fill at all and were unchanged when compared with post-operative controls. There was no progression progression of any post-operative gap and no evidence of new periacetabular radiolucent lines or lysis. No acetabular implant showed evidence of migration or needed revision for loosening. At last follow up the mean Harris Hip Score was 95. There were no dislocation or other complications. Discussion Short term results with porous tantalum acetabular component are encouraging: the bridging of the interface gaps and the absence of periacetabular radiolucencies indicate good mechanical and osteoconductive properties. Further follow-up will be required to confirm these results in the long term
Debye mass and heavy quark potential in a PNJL quark plasma
We calculate the Debye mass for the screening of the heavy quark potential in
a plasma of massless quarks coupled to the temporal gluon background governed
by the Polyakov loop potential within the PNJL model in RPA approximation. We
give a physical motivation for a recent phenomenological fit of lattice data by
applying the calculated Debye mass with its suppression in the confined phase
due to the Polyakov-loop to a description of the temperature dependence of the
singlet free energy for QCD with a heavy quark pair at infinite separation. We
compare the result to lattice data.Comment: 6 pages, 1 figure, contribution to Proceedings of the 6th
International Conference on "Critical Point and Onset of Deconfinement", to
appear in Phys. At. Nucl., vol. 7
Thermodynamics of the PNJL model
QCD thermodynamics is investigated by means of the Polyakov-loop-extended
Nambu Jona-Lasinio (PNJL) model, in which quarks couple simultaneously to the
chiral condensate and to a background temporal gauge field representing
Polyakov loop dynamics. The behaviour of the Polyakov loop as a function of
temperature is obtained by minimizing the thermodynamic potential of the
system. A Taylor series expansion of the pressure is performed. Pressure
difference and quark number density are then evaluated up to sixth order in
quark chemical potential, and compared to the corresponding lattice data. The
validity of the Taylor expansion is discussed within our model, through a
comparison between the full results and the truncated ones.Comment: 6 pages, 5 figures, Talk given at the Workshop for Young Scientists
on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions (Hot Quarks
2006), Villasimius, Italy, 15-20 May 200
Defining and predicting textbook outcomes for perihilar cholangiocarcinoma: analysis of factors improving achievement of desired postoperative outcomes
BACKGROUND: Definition of textbook outcome (TO), defined as a single indicator combining the most advantageous short-term outcomes, is still lacking for perihilar cholangiocarcinoma (PHC). The primary endpoint of the present study is to analyze the rate of achievement of a disease-specific TO for PHC within a high volume tertiary referral centre. Secondary endpoints are to identify predictive factors of TO-achievement and to analyze the impact of achieving TO on long-term results. METHODS: Between 2010 and 2022, a total of 237 patients undergoing combined liver and biliary resection for PHC at tertiary referral centre were included. Disease-specific TO were defined as: no 90-day mortality, no postoperative complications, no readmission, no intraoperative transfusions and resection margins. A logistic regression model was developed to identify predictors associated with TO-achievement. Kaplan-Meier curves were designed to determine TO's impact on survival. RESULTS: TO was achieved in 60 (25.3%) patients. At multivariate logistic regression, preoperative biliary drainage [odds ratio (OR) 2.90 (1.13-3.40), P =0.026], high prognostic nutritional index [OR 7.11 (6.71-9.43), P =0.007[ and minimally invasive approach [OR 3.57 (2.31-3.62), P =0.013] were identified as independent predictors of TO. High ASA score [OR 0.38 (0.17-0.82), P =0.013] decreased the odds of TO. A significant improvement in both overall survival and disease-free survival was associated to TO fulfilment. CONCLUSION: Since the achievement of TO correlates with better disease-free and overall survival, every effort should be made to ameliorate modifiable aspects prior to surery: management within referral centres with dedicated experience in biliary tract cancer and preoperative optimization protocol may positively contribute to improve postoperative outcomes, increasing the chance to obtain TO. Moreover, the implementation of advanced minimally invasive programs plays as well
Dietary Lippia citriodora extract in rabbit feeding: Effects on quality of carcass and meat
Due to consumer demand, in recent years considerable attention has been focused on the use of natural compounds in animal feed. The aim of this study was to evaluate the effect of dietary natural extract from Lippia citriodora (commonly named "limoncina"), titrated in verbascoside, on quality, measured as oxidative stability, fatty acid composition, alpha-tocopherol and retinol content and sensory traits of rabbit meat. Forty-five New Zealand white rabbits were randomly assigned to three age- and body-weight-balanced feeding groups of 15 animals each in which a conventional pelleted diet (CON) was supplemented with 1 or 2 kg t-1(low natural-extract (LNE) and high natural-extract (HNE) groups, respectively) of Lippia citriodora extract for 55 days. No influence on carcass characteristics and the chemical composition of meat was observed. A trend for a positive effect on alpha-tocopherol tissue content (P = 0.07) and on thiobarbituric reactive substance (TBARS) values was observed (P = 0.063) in Longissimus Lumborum muscle from the HNE group. The fatty acid profile of the meat was affected by dietary treatment with a significant decrease (P = 0.001) in saturated fatty acids and an increase (P = 0.01) in polyunsaturated fatty acids in both treated groups compared to the CON group. The supplementation with natural extract at the highest dosage improved the tenderness and juiciness of meat, highlighting a better consistency than CON and LNE groups. In conclusion, this study shows that the natural extract used has the potential to improve rabbit meat in order to produce functional food, without altering the chemical and physical characteristics of meat
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