151 research outputs found
The Master Field of QCD and the 'T Hooft Equation
We rewrite the action for in the light cone gauge only in terms of a
bilocal mesonic field. In this formalism the expansion can be done in a
straightforward way by a saddle point technique that determines the master
field to be identified with the vacuum expectation value of the bilocal field.
Finally we show that the equation of motion for the fluctuations around the
master field is identical with the 't Hooft meson equation.Comment: 7 pages, Latex, NORDITA-93-4
Dynamics of Electric Field Domains and Oscillations of the Photocurrent in a Simple Superlattice Model
A discrete model is introduced to account for the time-periodic oscillations
of the photocurrent in a superlattice observed by Kwok et al, in an undoped 40
period AlAs/GaAs superlattice. Basic ingredients are an effective negative
differential resistance due to the sequential resonant tunneling of the
photoexcited carriers through the potential barriers, and a rate equation for
the holes that incorporates photogeneration and recombination. The
photoexciting laser acts as a damping factor ending the oscillations when its
power is large enough. The model explains: (i) the known oscillatory static I-V
characteristic curve through the formation of a domain wall connecting high and
low electric field domains, and (ii) the photocurrent and photoluminescence
time-dependent oscillations after the domain wall is formed. In our model, they
arise from the combined motion of the wall and the shift of the values of the
electric field at the domains. Up to a certain value of the photoexcitation,
the non-uniform field profile with two domains turns out to be metastable:
after the photocurrent oscillations have ceased, the field profile slowly
relaxes toward the uniform stationary solution (which is reached on a much
longer time scale). Multiple stability of stationary states and hysteresis are
also found. An interpretation of the oscillations in the photoluminescence
spectrum is also given.Comment: 34 pages, REVTeX 3.0, 10 figures upon request, MA/UC3M/07/9
Boson Expansion Methods in (1+1)-dimensional Light-Front QCD
We derive a bosonic Hamiltonian from two dimensional QCD on the light-front.
To obtain the bosonic theory we find that it is useful to apply the boson
expansion method which is the standard technique in quantum many-body physics.
We introduce bilocal boson operators to represent the gauge-invariant quark
bilinears and then local boson operators as the collective states of the
bilocal bosons. If we adopt the Holstein-Primakoff type among various
representations, we obtain a theory of infinitely many interacting bosons,
whose masses are the eigenvalues of the 't Hooft equation. In the large
limit, since the interaction disappears and the bosons are identified with
mesons, we obtain a free Hamiltonian with infinite kinds of mesons.Comment: 20 pages, latex, no figures, journal version (no significant
changes), to appear in Phys. Rev.
Learning the game: Football fandom culture and the origins of practice
Based on the partial results of a doctoral programme, this article explores the significance of Pierre Bourdieu's theory of practice for explaining the experiential processes involved in becoming a football fan. Whilst recognizing value in the theoretical construct habitus, in the sense that football cultures appear to be self perpetuating (in part) based on histories of objective social conditions and accrued experiences, the findings indicate that caution must be taken not to overemphasize the structuring power of habitus and the unopposed continuation of tradition at the expense of the reflexive nature and subtle transformation of fandom practice in late modern life
Stakeholders, collaboration, food, and wine: The case of Jumilla’s Gastronomic Days
An emerging literature on gastronomic events highlights the growing interest among academics, event organisers and development agencies in identifying potential or actual outcomes from gastronomic events. Partly in response to such interest, this study seeks to contribute to the literature on events management, studying the contribution of various stakeholders involved in the ‘Gastronomic Days’ of Jumilla, Spain. Semi-structured, face-to-face, in-depth interviews were conducted with the managers and owners of four participating businesses to the event. The data collection was complemented through on-site visits, observations, and interviews with eight other local businesses. The findings underline the significance of collaboration among these participants to grow and sustain the event, as well as voluntary efforts by event ‘stakeholders.’ Importantly, a common objective was identified in the form of enhancing the image of the local products, and overall that of the region, to ‘convert’ residents, and also outside consumers and tourists to Jumilla’s products. These findings have significant implications for Jumilla’s community. In particular, the importance and efforts of a region’s food stakeholders in contributing to adding value and improving the local food culture emerge as useful aspects, with potential benefits for local food growers, hospitality and tourism sectors, and residents
HOXB7 expression by myeloma cells regulates their pro-angiogenic properties in multiple myeloma patients
The deregulation of the homeobox genes as homeoboxB (HOXB)-7 has been previously associated to tumor progression and angiogenesis; here we investigated the potential role of HOXB7 in the pro-angiogenic properties of multiple myeloma (MM) cells. We found that HOXB7 was expressed in 10 out of 22 MM patients analyzed at the diagnosis related to high bone marrow angiogenesis and overexpressed in about 40% of myeloma cell lines compared with normal plasma cells. Enforced HOXB7 expression in MM cells by a lentiviral vector significantly modified their transcriptional and angiogenic profile, checked by combined microarray and angiogenesis PCR analyses, upregulating VEGFA, FGF2, MMP2, WNT5a and PDGFA and downregulating thrombospoindin-2. The pro- and anti-angiogenic HOXB7-related gene signature was also validated in a large independent dataset of MM patients. Accordingly, MM-induced vessel formation was significantly increased by HOXB7 overexpression both in vitro angiogenic and chorioallantoic membrane assays, as well as the HOXB7 silencing by small interfering RNA inhibited the production of angiogenic factors, and the pro-angiogenic properties of MM cells. Finally, in SCID-NOD mice we confirmed that HOXB7 overexpression by MM cells stimulated tumor growth, increased MM-associated angiogenesis and the expression of pro-angiogenic genes by microarray analysis supporting the critical role of HOXB7 in the angiogenic switch in M
Adjuvant capecitabine in triple negative breast cancer patients with residual disease after neoadjuvant treatment: real-world evidence from CaRe, a multicentric, observational study
Background: In triple negative breast cancer patients treated with neoadjuvant chemotherapy, residual disease at surgery is the most relevant unfavorable prognostic factor. Current guidelines consider the use of adjuvant capecitabine, based on the results of the randomized CREATE-X study, carried out in Asian patients and including a small subset of triple negative tumors. Thus far, evidence on Caucasian patients is limited, and no real-world data are available. Methods: We carried out a multicenter, observational study, involving 44 oncologic centres. Triple negative breast cancer patients with residual disease, treated with adjuvant capecitabine from January 2017 through June 2021, were recruited. We primarily focused on treatment tolerability, with toxicity being reported as potential cause of treatment discontinuation. Secondarily, we assessed effectiveness in the overall study population and in a subset having a minimum follow-up of 2 years. Results: Overall, 270 patients were retrospectively identified. The 50.4% of the patients had residual node positive disease, 7.8% and 81.9% had large or G3 residual tumor, respectively, and 80.4% a Ki-67 >20%. Toxicity-related treatment discontinuation was observed only in 10.4% of the patients. In the whole population, at a median follow-up of 15 months, 2-year disease-free survival was 62%, 2 and 3-year overall survival 84.0% and 76.2%, respectively. In 129 patients with a median follow-up of 25 months, 2-year disease-free survival was 43.4%, 2 and 3-year overall survival 78.0% and 70.8%, respectively. Six or more cycles of capecitabine were associated with more favourable outcomes compared with less than six cycles. Conclusion: The CaRe study shows an unexpectedly good tolerance of adjuvant capecitabine in a real-world setting, although effectiveness appears to be lower than that observed in the CREATE-X study. Methodological differences between the two studies impose significant limits to comparability concerning effectiveness, and strongly invite further research
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
Meeting abstrac
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