122 research outputs found
Numerical Simulations Unveil Superradiant Coherence in a Lattice of Charged Quantum Oscillators
A system of charged oscillators interacting with the
electromagnetic field, spatially confined in a 3D lattice of sub-wavelength
dimension, can condense into a superradiant coherent state if appropriate
density and frequency conditions are met. In this state, the common frequency
of the oscillators and the plasma frequency of the charges
are combined into a frequency that is
off-shell with respect to the wavelength of the photon modes involved,
preventing them from propagating outside the material. Unlike other atomic
cavity systems, the frequency in this case is not determined by the
cavity itself but is defined by the periodic electrostatic potential that
confines the charged particles in the lattice. Additionally, the
electromagnetic modes involved have wave vectors distributed in all spatial
directions, resulting in a significant increase in coupling. The analytical
study of this system can be carried out in the limit of large by
searching for an approximation of the ground state via suitable coherent trial
states. Alternatively, numerical simulations can be employed for smaller
. In the numerical approach, it is possible to go beyond the
Rotating Wave Approximation (RWA) and introduce a dissipation term for the
photon modes. This dissipation term can account for the ohmic quench in a metal
and also consider photon losses at the boundary of the material. By utilizing
numerical solutions and Monte Carlo simulations, the presence of condensation
has been confirmed, and an energy gap of a few electron volts (eV) per particle
has been observed in typical metal crystals with protons bound to tetrahedral
or octahedral sites.Comment: 20 pages, 6 figure
The Pomeron in QCD
In the framework of Anisotropic Chromodynamics, a non-perturbative
realization of QCD, we develop the Low-Nussinov picture of the Pomeron. In this
approach all the usual problems of low pT perturbative calculations (infrared
divergence) are naturally absent. Thus, we are able to perform an ab initio
calculation of the hadron-hadron total cross section. The result is a cross
section of the same magnitude as indicated experimentally and approximately
energy-independent (with a log^2 s growth). We further discuss the pT
dependence of the hadron-hadron elastic-scattering cross section, which
displays all the experimentally observed features.Comment: 8 pages (LaTeX, plus 4 postscript figures in a separate file), report
number MITH 94/13 *** Replaced figures file with uuencoded, compressed,
tarred version **
The Savvidy ``ferromagnetic vacuum'' in three-dimensional lattice gauge theory
The vacuum effective potential of three-dimensional SU(2) lattice gauge
theory in an applied color-magnetic field is computed over a wide range of
field strengths. The background field is induced by an external current, as in
continuum field theory. Scaling and finite volume effects are analyzed
systematically. The first evidence from lattice simulations is obtained of the
existence of a nontrivial minimum in the effective potential. This supports a
``ferromagnetic'' picture of gluon condensation, proposed by Savvidy on the
basis of a one-loop calculation in (3+1)-dimensional QCD.Comment: 9pp (REVTEX manuscript). Postscript figures appende
Work ethics and general work attitudes in adolescents are related to quality of life, sense of coherence and subjective health – a Swedish questionnaire study
BACKGROUND: Working life is an important arena in most people's lives, and the working line concept is important for the development of welfare in a society. For young people, the period before permanent establishment in working life has become longer during the last two decades. Knowledge about attitudes towards work can help us to understand young people's transition to the labour market. Adolescents are the future workforce, so it seems especially important to notice their attitudes towards work, including attitudes towards the welfare system. The aim of this study was to describe and analyse upper secondary school students' work attitudes, and to explore factors related to these attitudes. METHODS: The sample consisted of 606 upper secondary school students. They all received a questionnaire including questions about quality of life (QOL), sense of coherence (SOC), subjective health and attitudes towards work. The response rate was 91%. A factor analysis established two dimensions of work attitudes. Multivariate analyses were carried out by means of logistic regression models. RESULTS: Work ethics (WE) and general work attitudes (GWA) were found to be two separate dimensions of attitudes towards work. Concerning WE the picture was similar regardless of gender or study programme. Males in theoretical programmes appeared to have more unfavourable GWA than others. Multivariate analyses revealed that good QOL, high SOC and good health were significantly related to positive WE, and high SOC was positively related to GWA. Being female was positively connected to WE and GWA, while studying on a practical programme was positively related to GWA only. Among those who received good parental support, GWA seemed more favourable. CONCLUSION: Assuming that attitudes towards work are important to the working line concept, this study points out positive factors of importance for the future welfare of the society. Individual factors such as female gender, good QOL, high SOC and good health as well as support from both parents, positive experience of school and work contacts related positively to attitudes towards work. Further planning and supportive work have to take these factors into account
Dressed for Sex: Red as a Female Sexual Signal in Humans
Background: In many non-human primate species, a display of red by a female serves as a sexual signal to attract male conspecifics. Red is associated with sex and romance in humans, and women convey their sexual interest to men through a variety of verbal, postural, and behavioral means. In the present research, we investigate whether female red ornamentation in non-human primates has a human analog, whereby women use a behavioral display of red to signal their sexual interest to men. Methodology/Principal Findings: Three studies tested the hypothesis that women use red clothing to communicate sexual interest to men in profile pictures on dating websites. In Study 1, women who imagined being interested in casual sex were more likely to display red (but not other colors) on their anticipated web profile picture. In Study 2, women who indicated interest in casual sex were more likely to prominently display red (but not other colors) on their actual web profile picture. In Study 3, women on a website dedicated to facilitating casual sexual relationships were more likely to prominently exhibit red (but not other colors) than women on a website dedicated to facilitating marital relationships. Conclusions/Significance: These results establish a provocative parallel between women and non-human female primates in red signal coloration in the mating game. This research shows, for the first time, a functional use of color in women’s sexual self-presentation, and highlights the need to extend research on color beyond physics, physiology, and preference to psychological functioning
Entourage: the immune microenvironment following follicular lymphoma
In follicular lymphoma, nonmalignant immune cells are important. Follicular lymphoma depends on CD4+ cells, but CD8+ cells counteract it. We hypothesized that the presence of follicular lymphoma is associated with higher CD4+ than CD8+ cell numbers in the tumor microenvironment but not in the immune system. Using flow cytometry, pre-treatment and follow-up CD4/CD8 ratios were estimated in the bone marrow, blood and lymph nodes of untreated follicular lymphoma patients in two independent data sets (N1=121; N2=166). The ratios were analyzed for their relation with bone marrow lymphoma involvement. Bone marrows were also investigated with immunohistochemistry. In either data set, the bone marrow CD4/CD8 ratios were higher in bone marrows involved with lymphoma (P=0.043 and 0.0002, respectively). The mean CD4/CD8 ratio was 1.0 in uninvolved and 1.4 in involved bone marrows. Also higher in involved bone marrows were CD4/CD56 and CD3CD25/CD3 ratios. No blood or lymph node ratios differed between bone marrow-negative and -positive patients. Sequential samples showed increased bone marrow CD4/CD8 ratios in all cases of progression to bone marrow involvement. Immunohistochemistry showed CD4+, CD57+, programmed death-1+, forkhead box protein 3+ and CD21+ cells accumulated inside the lymphoma infiltrates, whereas CD8+, CD56+ and CD68+ cells were outside the infiltrates. This study provides evidence in vivo that the microenvironment changes upon follicular lymphoma involvement
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