Características tecnológicas de la madera de Pinus pinea L. (pino piñonero) de Miramar

El Pinus pinea L. recibe como nombre común el de pino piñonero o doméstico, originario de la costa del Mediterráneo. Fue introducido al país en la época colonial y cultivado como árbol ornamental y frutal. Es frecuente encontrarlo en plazas, paseos y parques, brindando su sombra; en las estancias se lo cultvaba como frutal, del cual se obtenían buenas cosechas de piñones. Anualmente nuestro país importa setenta mil kilogramos y llegan al público al precio de treinta dólares por kilo de piñones pelados. Como referencia histórica, diremos que el pino de San Lorenzo, donde el General San Martín descansó bajo su sonbra, pertenece a esta especie. Como forestal, es utilizado en la tercera etapa de fijación de dunas, debido a su característica particular de prosperar en suelos sueltos. Vidal (6) expresa que su mejor área podría encontrarse en las ondulaciones de la costa marítima de la Provincia de Buenos Aires, en terrenos arenosos profundos, permeables, en sitios relativamente secos, en las estribaciones de Tandil, Córdoba, San Luis y en los valles y faldeos de exposición norte. En Europa, como árbol productor de madera, registra crecimientos de cuatro metros cúbicos por hectárea y por año, en turnos de ochenta años. En el país, con clima templado e inviernos menos rigurosos, con temperatura y humedad adecuada en época de crecimiento, alcanza el turno a los treinta años. La finalidad de este estudio es concretar las características físicas y mecánicas de la madera, que procede de una zona conocida, en una información de fácil manejo e interpretación y factible de comparación con las propiedades de otras especies, o de la misma especie cultivada en otras zonas. Se establece la resistencia promedio de cada ensayo y se calculan estadísticamente los valores mínimos aceptables. Las conclusiones podrán servir de guía a profesionales del ramo de la construcción e industrialización, para el cálculo y dimensiona- do de los elementos de madera que integran una obra. Además se busca poner en evidencia, las ventajas y deficiencias que presenta el material, en cada una de las solicitaciones a que sea sometido

Constraints on Supersymmetric Theories from μ→e,γ\mu\to e,\gamma

In the absence of any additional assumption it is natural to conjecture that sizeable flavour-mixing mass entries, $\Delta m^2$, may appear in the mass matrices of the scalars of the MSSM, i.e. $\Delta m^2\sim O(m^2)$. This flavour violation can still be reconciled with the experiment if the gaugino mass, $M_{1/2}$, is large enough, leading to a {\em gaugino dominance} framework (i.e. $M_{1/2}^2\gg m^2$), which permits a remarkably model--independent analysis. We study this possibility focussing our attention on the $\mu\rightarrow e,\gamma$ decay. In this way we obtain very strong and general constraints, in particular \frac{M_{1/2}^2}{\Delta m}\simgt 34\ {\rm TeV}. On the other hand, we show that our analysis and results remain valid for values of $m^2$ much larger than $\Delta m^2$, namely for \frac{\Delta m^2}{m^2}\simgt \frac{m^2} {10\ {\rm TeV^2}}, thus extending enormously their scope of application. Finally, we discuss the implications for superstring scenarios.Comment: 12 pages, Latex, 5 figures as uuencoded compressed postscript files, uses psfig.st

Focus Point SUSY at the LHC Revisited

The estimation of the backgrounds for gluino signals in focus point supersymmetry is extended by including the backgrounds from the production of four third generation quarks in the analysis. We find that these backgrounds are negligible if one uses the strong selection criteria proposed in the literature (including this analysis) for heavy gluino searches. Softer selection criteria often recommended for lighter gluino searches yield backgrounds which are small but numerically significant. We have also repeated the more conventional background calculations and compared our results with the other groups. We find that the size of the total residual background estimated by different groups using different event generators and hard kinematical cuts agree approximately. In view of the theoretical uncertainties in the leading order signal and background cross sections mainly due to the choice of the QCD scale, the gluino mass reach at the LHC cannot be pinpointed. However, requiring a signal with $\rm\geq 3$ tagged b-jets (instead of the standard choice of $\rm\geq 2$) it is shown that gluino masses close to 2 TeV can be probed at the LHC for a range of reasonable choices of the QCD scale for an integrated luminosity of 300 fb$^{-1}$.Comment: 17 pages, 4 figures, minor typos correctio

Higgs and Supersymmetric Particle Signals at the Infrared Fixed Point of the Top Quark Mass

We study the properties of the Higgs and supersymmetric particle spectrum associated with the infrared fixed point solution of the top quark mass in the MSSM. We concentrate on the possible detection of these particles, analysing the deviations from the Standard Model predictions for the leptonic and hadronic variables measured at LEP and for the decay rate $b\rightarrow s\gamma$. We consider the low and moderate $\tan \beta$ regime, and we study both, the cases of universal and non--universal soft supersymmetry breaking parameters at high energies. In the first case, for any given value of the top quark mass, the Higgs and sparticle spectra are completely determined as a function of two soft supersymmetry breaking parameters. In the case of non--universality, instead, the strong correlations between the sparticle masses are relaxed, allowing a richer structure for the precision data variables. We show, however, that the requirement that the low energy theory proceeds from a grand unified theory with a local symmetry group including $SU(5)$, strongly constrains the set of possible indirect experimental signatures. As a general feature, whenever a significant deviation from the Standard Model value of the precision data variables is predicted, a light sparticle, visible at LEP2, appears in the spectrum.Comment: 42 pages, 16 figures (not included), CERN-TH.7393/9

Flavor Symmetries and The Problem of Squark Degeneracy

If supersymmetry exists at low energies, it is necessary to understand why the squark spectrum exhibits sufficient degeneracy to suppress flavor changing neutral currents. In this note, we point out that gauged horizontal symmetries can yield realistic quark mass matrices, while at the same time giving just barely enough squark degeneracy to account for neutral $K$-meson phenomenology. This approach suggests likely patterns for squark masses, and indicates that there could be significant supersymmetric contributions to $B-\bar{B}$ and $D-\bar{D}$ mixing and CP violation in the $K$ and $B$ systems.Comment: preprint SCIPP 93/04,SLAC-PUB-6147, 14 pages, 4 tables included; uses macro package TABLES.TEX and phyzzx forma

Características tecnológicas de la madera de pino insigne (Pinus radiata Don.) de Balcarce

El presente trabajo señala las características tecnológicas de las especies maderables que crecen el la Provincia de 'Buenos Aires, comenzando por el estudio del Pinus radiata Don., plantado en las sierras de Balcarce. La finalidad es verificar el comportamiento de la madera de las diferentes especies con el propósito de que sus resultados puedan usarse para seleccionar las especies a plantar en el futuro. Se evalúan los ensayos físicos y mecánicos más conocidos de la madera al estado verde y seca al aire, con ajuste a valores de contenido de humedad del 18 %. Además, y por medio de coeficientes tecnológicos, se hace la transformación de las tensiones obtenidas, a valores comparables.The purpose of the study of the timber-yielding species that grow in the Province of Buenos Aires, is to determine its technological characteristics. The study begins with the Pinus radiata Don. planted in the Sierras of Balcarce. The aim is to verify the behavior of the wood of the various species planted, and apply the results for better selection of future planting. This study evaluates the physical and mechanical test know up to date, of the wood in green state and dry in the oppen air with adjustment of values to a content of 15 % of humidity. Moreover the transformation of the tensions obtanied is done by the technological coeficients to comparative values

Exotic particles below the TeV from low scale flavour theories

A flavour gauge theory is observable only if the symmetry is broken at relatively low energies. The intrinsic parity-violation of the fermion representations in a flavour theory describing quark, lepton and higgsino masses and mixings generically requires anomaly cancellation by new fermions. Benchmark supersymmetric flavour models are built and studied to argue that: i) the flavour symmetry breaking should be about three orders of magnitude above the higgsino mass, enough also to efficiently suppress FCNC and CP violations coming from higher-dimensional operators; ii) new fermions with exotic decays into lighter particles are typically required at scales of the order of the higgsino mass.Comment: 19 pages, references added, one comment and one footnote added, results unchange

Improved Higgs Mass Stability Bound in the Standard Model and Implications for Supersymmetry

We re-examine the lower bound on the mass of the Higgs boson, $M_H$, from Standard Model vacuum stability including next-to-leading-log radiative corrections. This amounts to work with the full one-loop effective potential, $V(\phi)$, improved by two-loop RGE, and allows to keep control of the scale invariance of $V$ in a wide range of the $\phi$-field. Our results show that the bound is ${\cal O}\ (10\ GeV)$ less stringent than in previous estimates. In addition we perform a detailed comparison between the SM lower bounds on $M_H$ and the supersymmetric upper bounds on it. It turns out that depending on the actual value of the top mass, $M_t$, the eventually measured Higgs mass can discard the pure SM, the Minimal Supersymmetric Standard Model or both.Comment: 11 pages + 7 postscript figures appended at the end, Latex, IEM-FT-93/9

Neutralino Dark Matter in Minimal Supergravity: Direct Detection vs. Collider Searches

We calculate expected event rates for direct detection of relic neutralinos as a function of parameter space of the minimal supergravity model. Numerical results are presented for the specific case of a $^{73}$Ge detector. We find significant detection rates ($R> 0.01$ events/kg/day) in regions of parameter space most favored by constraints from $B\to X_s\gamma$ and the cosmological relic density of neutralinos. The detection rates are especially large in regions of large $\tan\beta$, where many conventional signals for supersymmetry at collider experiments are difficult to detect. If the parameter $\tan\beta$ is large, then there is a significant probability that the first direct evidence for supersymmetry could come from direct detection experiments, rather than from collider searches for sparticles.Comment: 25 page REVTEX file including 9 PS figure

Product Groups, Discrete Symmetries, and Grand Unification

We study grand unified theories based on an SU(5)xSU(5) gauge group in which the GUT scale, M_{GUT}, is the VEV of an exact or approximate modulus, and in which fast proton decay is avoided through a combination of a large triplet mass and small triplet couplings. These features are achieved by discrete symmetries. In many of our models, M_{GUT} is generated naturally by the balance of higher dimension terms that lift the GUT modulus potential, and soft supersymmetry breaking masses. The theories often lead to interesting patterns of quark and lepton masses. We also discuss some distinctions between grand unified theories and string unification.Comment: 23 pages; no figures; revtex