6,093 research outputs found
Graphene tests of Klein phenomena
Graphene is characterized by chiral electronic excitations. As such it
provides a perfect testing ground for the production of Klein pairs
(electron/holes). If confirmed, the standard results for barrier phenomena must
be reconsidered with, as a byproduct, the accumulation within the barrier of
holes.Comment: 8 page
Shopping centres revisited: exploring new attributes of attractiveness
Traditional retailing is facing tough challenges, driven not least by the trend towards online shopping. This paper revisits shopping centres research in light of the recent increasing role of technologies, leisure activities and changes in consumer behaviour. Drawing upon 10,544 consumers’ unsolicited communications on Twitter relating to the 19 main shopping centres in UK that were posted in May 2019, this research seeks to understand how retail attributes are unevenly distributed across consumers’ evaluations to define the attributes driving consumers’ evaluations of retail-leisure complexes. Results demonstrate the impact of each identified attribute on preferences for retail-leisure complexes. In particular, findings provide important insights for scholars and practitioners related to the design of future attractive shopping centres. Shopping centres can play an important role in contributing to the viability and vitality of towns. We consider the findings in the light of wider policy and regulatory debates
Modern circular economy: Corporate strategy, supply chain, and industrial symbiosis
This paper analyses the firms\u2019 chances to consider circular economy as a part of the corporate strategy. The analysis of four Italian firms engaged in circular economy programs allows us to detect its connections with the corporate strategy, the real activities involved, the supply chain network ensuring circularity, the industrial symbiosis, as well as the links with performance. Our findings highlight that circular economy is a true business lever when the corporate strategy complements and supports its development. This allows firms to achieve high level targets that go beyond the traditional targets of social, environmental, and economic performance, and include circular supply chain, eco-innovations, and industrial symbiosis
Wave and Particle Limit for Multiple Barrier Tunneling
The particle approach to one-dimensional potential scattering is applied to
non relativistic tunnelling between two, three and four identical barriers. We
demonstrate as expected that the infinite sum of particle contributions yield
the plane wave results. In particular, the existence of resonance/transparency
for twin tunnelling in the wave limit is immediately obvious. The known
resonances for three and four barriers are also derived. The transition from
the wave limit to the particle limit is exhibit numerically.Comment: 15 pages, 3 figure
Evidence for impurity-induced frustration in La2CuO4
Zero-field muon spin rotation and magnetization measurements were performed
in La2Cu{1-x}MxO4, for 0<x< 0.12, where Cu2+ is replaced either by M=Zn2+ or by
M=Mg2+ spinless impurity. It is shown that while the doping dependence of the
sublattice magnetization (M(x)) is nearly the same for both compounds, the
N\'eel temperature (T_N(x)) decreases unambiguously more rapidly in the
Zn-doped compound. This difference, not taken into account within a simple
dilution model, is associated with the frustration induced by the Zn2+ impurity
onto the Cu2+ antiferromagnetic lattice. In fact, from T_N(x) and M(x) the spin
stiffness is derived and found to be reduced by Zn doping more significantly
than expected within a dilution model. The effect of the structural
modifications induced by doping on the exchange coupling is also discussed.Comment: 4 pages, 4 figure
Osservazioni Citotassonomiche Su Scilla Barbacaprae, Endemismo Cirenaico, E Sue Affinita' Con Scilla Villosa
RIASSUNTOViene analizzato il cariotipo di Scilla barba caprae, specie endemica di Derna (Cirenaica settentrionale). Il risultato di questa indagine, effettuata su bulbi coltivati nell'Orto Botanico di Catania, e stato il rinvenimento di un corredo cromosomico diploide: z = 2n = 2x = 14 = 2L + 2M1 + 2M2 + 2M3S3 + 2M4 + 2S1 + 2S2.La comparazione fra Scilla barba-caprae e Scilla villosa, che e la specie tassonomicamente piu vicina, ha permesso di evidenziare numerose differenze riguardanti sia il cariotipo che il fenotipo, che consentono di separare le due entita a livello specifico.In particolare il cariotipo di Scilla villosa (2n = 20) differisce da quello fondamentale 2n= 16, relativo alle entita appartenenti al ciclo di Scilla peruviana, per avere in piu quattro cromosomi, mentre quello di Scilla barba-caprae (2n = 14) ne differisce per avere due cromosomi in meno e per la presenza della coppia 2M3S3 formatasi in seguito a fenomeni di traslocazione + delezione
Barrier Paradox in the Klein Zone
We study the solutions for a one-dimensional electrostatic potential in the
Dirac equation when the incoming wave packet exhibits the Klein paradox (pair
production). With a barrier potential we demonstrate the existence of multiple
reflections (and transmissions). The antiparticle solutions which are
necessarily localized within the barrier region create new pairs with each
reflection at the potential walls. Consequently we encounter a new paradox for
the barrier because successive outgoing wave amplitudes grow geometrically.Comment: 10 page
Effective gluon mass and infrared fixed point in QCD
We report on a special type of solutions for the gluon propagator of pure
QCD, obtained from the corresponding non-linear Schwinger-Dyson equation
formulated in the Feynman gauge of the background field method. These solutions
reach a finite value in the deep infrared and may be fitted using a massive
propagator, with the crucial characteristic that the effective ``mass''
employed depends on the momentum transfer. Specifically, the gluon mass falls
off as the inverse square of the momentum, as expected from the
operator-product expansion. In addition, one may define a dimensionless
quantity, which constitutes the generalization in a non-Abelian context of the
universal QED effective charge. This strong effective charge displays
asymptotic freedom in the ultraviolet whereas in the low-energy regime it
freezes at a finite value, giving rise to an infrared fixed point for QCD.Comment: 6 pages, 2 figures, Talk given at QCD@work 2007, Martina Franca,
Italy, 16-20 June 200
Secondary Baryon Asymmetry in pi(+-)p Collisions
The process of secondary baryon production in pi(+-)p collisions at high
energies in the central and forward fragmentation regions is considered in the
framework of the Quark-Gluon String Model. The contribution of the
string-junction mechanism to the baryon production is analysed. The results of
numerical calculations are in reasonable agreement with the experimental data
on the Lambda/bar(Lambda) and p/bar(p)$ asymmetries.Comment: Contribution to the Proceedings of QCD@Work 2007, International
Workshop on Quantum Chromodynamics, Theory and Experiment, Martina
Franca-Valle d'Itria, Italy, June 16-20, 2007 (6 pages and 4 figures
Partial purification and MALDI-TOF MS analysis of UN1, a tumor antigen membrane glycoprotein.
UN1 is a membrane glycoprotein that is expressed in immature human thymocytes, a subpopulation of peripheral T lymphocytes, the HPB acute lymphoblastic leukemia (ALL) T-cell line and fetal thymus. We previously reported the isolation of a monoclonal antibody (UN1 mAb) recognizing the UN1 protein that was classified as "unclustered" at the 5th and 6th International Workshop and Conference on Human Leukocyte Differentiation Antigens. UN1 was highly expressed in breast cancer tissues and was undetected in non-proliferative lesions and in normal breast tissues, indicating a role for UN1 in the development of a tumorigenic phenotype of breast cancer cells. In this study, we report a partial purification of the UN1 protein from HPB-ALL T cells by anion-exchange chromatography followed by immunoprecipitation with the UN1 mAb and MALDI-TOF MS analysis. This analysis should assist in identifying the amino acid sequence of UN
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