Closing the SU(3)L⊗U(1)XSU(3)_L\otimes U(1)_X Symmetry at Electroweak Scale

We show that some models with $SU(3)_C\otimes SU(3)_L\otimes U(1)_X$ gauge symmetry can be realized at the electroweak scale and that this is a consequence of an approximate global $SU(2)_{L+R}$ symmetry. This symmetry implies a condition among the vacuum expectation value of one of the neutral Higgs scalars, the $U(1)_X$'s coupling constant, $g_X$, the sine of the weak mixing angle $\sin\theta_W$, and the mass of the $W$ boson, $M_W$. In the limit in which this symmetry is valid it avoids the tree level mixing of the $Z$ boson of the Standard Model with the extra $Z^\prime$ boson. We have verified that the oblique $T$ parameter is within the allowed range indicating that the radiative corrections that induce such a mixing at the 1-loop level are small. We also show that a $SU(3)_{L+R}$ custodial symmetry implies that in some of the models we have to include sterile (singlets of the 3-3-1 symmetry) right-handed neutrinos with Majorana masses, being the see-saw mechanism mandatory to obtain light active neutrinos. Moreover, the approximate $SU(2)_{L+R}\subset SU(3)_{L+R}$ symmetry implies that the extra non-standard particles of these 3-3-1 models can be considerably lighter than it had been thought before so that new physics can be really just around the corner.Comment: 32 pages, no figure, RevTeX. Some typos correcte

Digital media inhibit self-regulatory private speech use in preschool children: The “digital bubble effect”

Preschoolers spend much time with digital media and some are concerned about impacts on language development. Private speech (PS) is self-talk children use during play, representing a necessary form of self-regulation. This study examined whether modality (material vs. digital) matters for children's PS. Twenty-nine White 5-yr-olds (52% female) completed the Tower of London task twice - once as a material version and once on a tablet. Children used more PS on the material than digital version of the task (d=0.46). During the material task, the typical pattern of increased PS as difficulty increased appeared. However, during the digital task, PS declined as difficulty increased. Digital games may inhibit children's use of PS for self-regulation, having implications for executive function development

Integral field spectroscopy of nitrogen overabundant blue compact dwarf galaxies

We study the spatial distribution of the physical properties and of oxygen and nitrogen abundances in three Blue Compact Dwarf Galaxiess (HS 0128+2832, HS 0837+4717 and Mrk 930) with a reported excess of N/O in order to investigate the nature of this excess and, particularly, if it is associated with Wolf-Rayet (WR) stars We have observed these BCDs by using PMAS integral field spectroscopy in the optical spectral range (3700 - 6900 {\AA}), mapping their physical-chemical properties, using both the direct method and appropriate strong-line methods. We make a statistical analysis of the resulting distributions and we compare them with the integrated properties of the galaxies. Our results indicate that outer parts of the three galaxies are placed on the "AGN-zone" of the [NII]/H{\alpha} vs. [OIII]/H{\beta} diagnostic diagram most likely due to a high N/O combined with the excitation structure in these regions. From the statistical analysis, it is assumed that a certain property can be considered as spatially homogeneous (or uniform) if a normal gaussian function fits its distribution in several regions of the galaxy. Moreover, a disagreement between the integrated properties and the mean values of the distribution usually appears when a gaussian does not fit the corresponding distribution. We find that for Mrk 930, the uniformity is found for all parameters, except for electron density and reddening. The rotation curve together with the H{\alpha} map and UV images, reveal a perturbed morphology and possible interacting processes. The N/O is found to be constant in the three studied objects at spatial scales of the order of several kpc so we conclude that the number of WR stars estimated from spectroscopy is not sufficient to pollute the ISM and to produce the observed N/O excess in these objectsComment: 17 pages, 14 figures, accepted for publication in Astronomy & Astrophysic

Late Bronze Age Hoard studied by PIXE

The hoards of metallic objects belonging to the Late European Bronze Age can be interpreted differently depending on the type, number and composition of the artefacts. PIXE analysis has been performed in nine items from the Hoard of Freixanda in Portugal comprising 4 socket axes, a palstave axe, a ring, a chisel, a dagger, and a casting debris. Besides the composition of the main matrix elements, that is Cu and Sn, the amount of trace elements of interest like, As, Pb, Ni and Ag has been determined using this ion beam technique. The high tin content alloy and the high purity of the metals from the Freixanda hoard are characteristic of the Portuguese and Spanish Late Bronze Age metallurgy, supporting the idea of a regional production

CONFIDENCE: achievements and way forward

The project CONFIDENCE (COping with uNcertainties For Improved modelling and DEcision making in Nuclear emergenCiEs) final dissemination event attracted 88 participants to review and discuss the project results and provide ideas for future research work. The workshop highlighted progress in understanding uncertainties in all phases of an emergency. It was also demonstrated that consideration of uncertainties are important when developing countermeasure strategies. Stakeholder engagement as well as societal and ethical aspects in decision making have to be considered. Formal decision making tools were improved and tested. In addition, CONFIDENCE participants, representatives of international organisations and end users, provided their ideas on research needs and the way forward

The Higgs Sector of the Minimal 3 3 1 Model Revisited

The mass spectrum and the eigenstates of the Higgs sector of the minimal 3 3 1 model are revisited in detail. There are discrepancies between our results and previous results by another author.Comment: 20 pages, latex, two figures. One note and one reference are adde

Productividad aérea y dinámica de nutrientes en una repoblación de Pinus pinaster ait. sometida distintos regímenes de claras

Thinning of different intensity have been carried out on a Pinus pinaster plantation and results have been compared with that of a control treatment and one plot with the maximum biological density for this species and age. The experimental design consists of randomized blocks. Four inventories were made in summer in 1984, 1988, 1992 and 1996. With this information the volume, basal area and number of tree before thinning, thinning and after thinning were calculated. Standing biomass and mineral element concentration before thinning, biomass removed with thinning and standing biomass after thinning have been estimated trough inventories and subsequent determination of modular values (a sample with 100 trees). Litter fall represented by needles fall and dead branches has been measured as well as its evolution through the year on plots representing four different stand densities.En una repoblación de Pinus pinaster Ait. se ha aplicado un programa de claras de distinta intensidad, que se comparan con parcelas testigos y con una parcela en la que se alcanza la máxima densidad biológica para esta especie y edad. Se realizaron cuatro inventarios durante los veranos de 1984, 1988, 1992 y 1996. Con esta información se ha estimado el volumen maderable, el área basimétrica y el número de pies/ha antes de la clara, la masa extraída y la masa principal después de la clara. Mediante la medición de 100 árboles tipo se calcularon los valores modulares, por clases diamétricas de 5 cm de amplitud. Aplicando los valores modulares a la distribución diamétrica de cada tratamiento se ha estimado la biomasa aérea total antes de la clara, la biomasa aérea extraída por la clara y la biomasa aérea que persiste después de la clara. Por diferencia entre inventarios se ha estimado el crecimiento medio y corriente en diámetro, altura, área basimétrica y volumen, así como los crecimientos medio y corriente en biomasa aérea total para cada tratamiento. Se cuantificó el desfronde total en cada tratamiento selvícola. Para el caso de las acículas, por medio de una muestra de 50 contenedores, de 0,25 m2, se realizó su seguimiento mensual durante 10 años. El desfronde anual de ramas, piñas y corteza (conjuntamente) se cuantificó por medio de una muestra de 10 subparcelas de 4 m2. Por último se estimó la cantidad de acículas acumuladas sobre la superficie del suelo (barrujo) en 1985, 1988, 1992 y 1995 para cada tratamiento

Relating the Quark and Gluon Condensates Through the QCD Vacuum Energy

Using the Cornwall-Jackiw-Tomboulis effective potential for composite operators we compute the QCD vacuum energy as a function of the dynamical quark and gluon propagators, which are related to their respective condensates as predicted by the operator product expansion. The identification of this result to the vacuum energy obtained from the trace of the energy-momentum tensor allow us to study the gluon self-energy, verifying that it is fairly represented in the ultraviolet by the asymptotic behavior predicted by the operator product expansion, and in the infrared it is frozen at its asymptotic value at one scale of the order of the dynamical gluon mass. We also discuss the implications of this identity for heavy and light quarks. For heavy quarks we recover, through the vacuum energy calculation, the relation m_{f} \sim - {1/12} \gc obtained many years ago with QCD sum rules.Comment: 21 pages, LaTeX, final version to appear in Physical Review

Hysteresis and Fractional Matching in Thin Nb Films with Rectangular Arrays of Nanoscaled Magnetic Dots

We have investigated the periodic pinning of magnetic flux quanta in thin Nb films with rectangular arrays of magnetic dots. In this type of pinning geometry, a change in the periodicity and shape of the minima in the magnetoresistance occurs for magnetic fields exceeding a certain threshold value. This has been explained recently in terms of a reconfiguration transition of the vortex lattice due to an increasing vortex-vortex interaction with increasing magnetic field. In this picture the dominating elastic energy at high fields forces the vortex lattice to form a square symmetry rather than being commensurate to the rectangular geometry of the pinning array. In this paper we present a comparative study of rectangular arrays with Ni-dots, Co-dots and holes. In the magnetic dot arrays, we found a strong fractional matching effect up to the second order matching field. In contrast, no clear fractional matching is seen after the reconfiguration. Additionally, we discovered the existence of hysteresis in the magnetoresistance in the crossover between the low and the high field regime. We found evidence that this effect is correlated to the reconfiguration phenomenon rather than to the magnetic state of the dots. The temperature and angular dependences of the effect have been measured and possible models are discussed to explain this behavior.Comment: 1 Table, 5 Figure