12,187 research outputs found

    Optical analogue of spontaneous symmetry breaking induced by tachyon condensation in amplifying plasmonic arrays

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    We study analytically and numerically an optical analogue of tachyon condensation in amplifying plasmonic arrays. Optical propagation is modeled through coupled-mode equations, which in the continuous limit can be converted into a nonlinear one-dimensional Dirac-like equation for fermionic particles with imaginary mass, i.e. fermionic tachyons. We demonstrate that the vacuum state is unstable and acquires an expectation value with broken chiral symmetry, corresponding to the homogeneous nonlinear stationary solution of the system. The quantum field theory analogue of this process is the condensation of unstable fermionic tachyons into massive particles. This paves the way for using amplifying plasmonic arrays as a classical laboratory for spontaneous symmetry breaking effects in quantum field theory.Comment: 5 pages, 5 figure

    How Do Maternal Subclinical Symptoms Influence Infant Motor Development during the First Year of Life?

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    An unavoidable reciprocal influence characterizes the mother-child dyad. Within this relationship, the presence of depression, somatization, hostility, paranoid ideation, and interpersonal sensitivity symptoms at a subclinical level and their possible input on infant motor competences has not been yet considered. Bearing in mind that motor abilities represent not only an indicator of the infant\u2019s health-status, but also the principal field to infer his/her needs, feelings and intentions, in this study the quality of infants\u2019 movements were assessed and analyzed in relationship with the maternal attitudes. The aim of this research was to investigate if/how maternal symptomatology may pilot infant\u2019s motor development during his/her first year of life by observing the characteristics of motor development in infants aged 0\u201311 months. Participants included 123 mothers and their infants (0\u201311 months-old). Mothers\u2019 symptomatology was screened with the Symptom Checklist-90-Revised (SCL-90-R), while infants were tested with the Peabody Developmental Motor Scale-Second Edition. All dyads belonged to a non-clinical population, however, on the basis of SCL-90-R scores, the mothers\u2019 sample was divided into two groups: normative and subclinical. Descriptive, t-test, correlational analysis between PDMS-2 scores and SCL-90-R results are reported, as well as regression models results. Both positive and negative correlations were found between maternal perceived symptomatology, Somatization (SOM), Interpersonal Sensitivity (IS), Depression (DEP), Hostility (HOS), and Paranoid Ideation (PAR) and infants\u2019 motor abilities. These results were further verified by applying regression models to predict the infant\u2019s motor outcomes on the basis of babies\u2019 age and maternal status. The presence of positive symptoms in the SCL-90-R questionnaire (subclinical group) predicted good visual-motor integration and stationary competences in the babies. In particular, depressive and hostility feelings in mothers seemed to induce an infant motor behavior characterized by a major control of the environmental space. When mothers perceived a higher level of hostility and somatization, their babies showed difficulties in sharing action space, such as required in the development of stationary positions and grasping abilities. In a completely different way, when infants can rely on a mother with low-perceived symptoms (normative group) his/her motor performances develop with a higher degree of freedom/independence. These findings suggest, for the first time, that even in a non- clinical sample, mother\u2019s perceived-symptoms can produce important consequences not in infant motor development as a whole, but in some specific areas, contributing to shape the infant\u2019s motor ability and his/her capability to act in the world

    Leadership traits, divergent thinking, and innovation in higher education

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    The topic of leadership is critical today as leaders‚Äô decision-making processes affect political, social, and economic conditions globally. Considering market fluctuations and shifts, political uncertainty, environmental threats, and global societal issues, the question of leadership is at the heart of issues faced today as leaders impact people at all levels of society. The discussion regarding leadership has centered on the need for high-level critical and creative thinkers and has shifted towards academia as a source for innovation. Educational institutions are under a high level of scrutiny and pressure to prepare graduates effectively for a volatile and unpredictable global market, yet the educational model has been slow to change and adapt to market conditions. This study identified the relationship between the institutional environment, leader‚Äôs traits, and divergent thinking to provide insight into the characteristics that drive innovation in the academic setting. The research involved a large-scale national study of college and university leaders and focused on leadership traits, divergent thinking, and innovation. Findings indicated negative relationships between the demographic attributes of gender and level of education, and innovation. Leaders with the traits of ‚ÄúConscientiousness‚ÄĚ and ‚ÄúLack of Emotional Stability‚ÄĚ negatively impacted innovation and institutional characteristics of location and type negatively affected organizational creativity. There was a significantly positive relationship between the institutional environment and three measured levels of innovation

    Efficacy of Two Common Methods of Application of Residual Insecticide for Controlling the Asian Tiger Mosquito, Aedes albopictus (Skuse), in Urban Areas

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    After its first introduction in the 1980's the Asian tiger mosquito, Aedes albopictus (Skuse), has spread throughout Southern Europe. Ae. albopictus is considered an epidemiologically important vector for the transmission of many viral pathogens such as the yellow fever virus, dengue fever and Chikungunya fever, as well as several filarial nematodes such as Dirofilaria immitis or D. repens. It is therefore crucial to develop measures to reduce the risks of disease transmission by controlling the vector populations. The aim of the study was to compare the efficacy of two application techniques (mist vs. stretcher sprayer) and two insecticides (Etox based on the nonester pyrethroid Etofenprox vs. Microsin based on the pyrethroid type II Cypermetrin) in controlling adult tiger mosquito populations in highly populated areas. To test the effect of the two treatments pre- and post-treatment human landing rate counts were conducted for two years. After one day from the treatment we observed a 100% population decrease in mosquito abundance with both application methods and both insecticides. However, seven and 14 days after the application the stretcher sprayer showed larger population reductions than the mist sprayer. No effect of insecticide type after one day and 14 days was found, while Etox caused slightly higher population reduction than Microsin after seven days. Emergency measures to locally reduce the vector populations should adopt adulticide treatments using stretcher sprayers. However, more research is still needed to evaluate the potential negative effects of adulticide applications on non-target organisms

    Non-equilibrium fluctuations in a driven stochastic Lorentz gas

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    We study the stationary state of a one-dimensional kinetic model where a probe particle is driven by an external field E and collides, elastically or inelastically, with a bath of particles at temperature T. We focus on the stationary distribution of the velocity of the particle, and of two estimates of the total entropy production \Delta s_tot. One is the entropy production of the medium \Delta s_m, which is equal to the energy exchanged with the scatterers, divided by a parameter \theta, coinciding with the particle temperature at E=0. The other is the work W done by the external field, again rescaled by \theta. At small E, a good collapse of the two distributions is found: in this case the two quantities also verify the Fluctuation Relation (FR), indicating that both are good approximations of \Delta s_tot. Differently, for large values of E, the fluctuations of W violate the FR, while \Delta s_m still verifies it.Comment: 6 pages, 4 figure

    Interface pinning and slow ordering kinetics on infinitely ramified fractal structures

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    We investigate the time dependent Ginzburg-Landau (TDGL) equation for a non conserved order parameter on an infinitely ramified (deterministic) fractal lattice employing two alternative methods: the auxiliary field approach and a numerical method of integration of the equations of evolution. In the first case the domain size evolves with time as L(t)‚ąľt1/dwL(t)\sim t^{1/d_w}, where dwd_w is the anomalous random walk exponent associated with the fractal and differs from the normal value 2, which characterizes all Euclidean lattices. Such a power law growth is identical to the one observed in the study of the spherical model on the same lattice, but fails to describe the asymptotic behavior of the numerical solutions of the TDGL equation for a scalar order parameter. In fact, the simulations performed on a two dimensional Sierpinski Carpet indicate that, after an initial stage dominated by a curvature reduction mechanism \`a la Allen-Cahn, the system enters in a regime where the domain walls between competing phases are pinned by lattice defects. The lack of translational invariance determines a rough free energy landscape, the existence of many metastable minima and the suppression of the marginally stable modes, which in translationally invariant systems lead to power law growth and self similar patterns. On fractal structures as the temperature vanishes the evolution is frozen, since only thermally activated processes can sustain the growth of pinned domains.Comment: 16 pages+14 figure

    Oral malodor in Special Care Patients: current knowledge

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    Epidemiological studies report that about 50% of the population may have oral malodor with a strong social and psychological impact in their daily life. When intra-oral causes are excluded, referral to an appropriate medical specialist is paramount for management and treatment of extra-oral causes. The intra-oral causes of halitosis are highly common, and the dentist is the central clinician to diagnose and treat them. Pseudohalitosis or halitophobia may occur and an early identification of these conditions by the dentist is important in order to avoid unnecessary dental treatments for patients who need psychological or psychiatric therapy. The organoleptic technique is still considered the most reliable examination method to diagnose genuine halitosis. Special needs patients are more prone than others to have oral malodor because of concurrent systemic or metabolic diseases, and medications. The present report reviews halitosis, its implications, and the management in special care dentistry

    Raman spectroscopy study of the interface structure in (CaCuO2)n/(SrTiO3)m superlattices

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    Raman spectra of CaCuO2/SrTiO3 superlattices show clear spectroscopic marker of two structures formed in CaCuO2 at the interface with SrTiO3. For non-superconducting superlattices, grown in low oxidizing atmosphere, the 425 cm-1 frequency of oxygen vibration in CuO2 planes is the same as for CCO films with infinite layer structure (planar Cu-O coordination). For superconducting superlattices grown in highly oxidizing atmosphere, a 60 cm-1 frequency shift to lower energy occurs. This is ascribed to a change from planar to pyramidal Cu-O coordination because of oxygen incorporation at the interface. Raman spectroscopy proves to be a powerful tool for interface structure investigation

    Lattice Boltzmann Method for mixtures at variable Schmidt number

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    When simulating multicomponent mixtures via the Lattice Boltzmann Method, it is desirable to control the mutual diffusivity between species while maintaining the viscosity of the solution fixed. This goal is herein achieved by a modification of the multicomponent Bhatnagar-Gross-Krook (BGK) evolution equations by introducing two different timescales for mass and momentum diffusion. Diffusivity is thus controlled by an effective drag force acting between species. Numerical simulations confirm the accuracy of the method for neutral binary and charged ternary mixtures in bulk conditions. The simulation of a charged mixture in a charged slit channel show that the conductivity and electro-osmotic mobility exhibit a departure from the Helmholtz-Smoluchowski prediction at high diffusivity.Comment: 18 pages, 6 figure

    Studies in the synthesis of tetracyclines

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