Aportació al coneixement de l"herbari Trèmols de l"Institut Botànic de Barcelona.

The herbarium BC-Trèmols was created during the second half of the 19th century by the Catalan chemist and botanist Frederic Trèmols Borrell. Between 1930 and 1960, the technician Antoni Marcos carried out a thorough review. The current collection consists of approximately 9000 specimen sheets; is made up of 58 volumes reordered by Marcos,two volumes with the original structure, four boxes of Hieracium and 85 boxes with additional material. Up to now 22 volumes and four boxes of Hieracium have been computerized (3695 specimens); we made an inventory at genus level of all volumes, and we computerized the original catalogue of the herbarium and the existing taxonomical fiches. We have also developed a preliminary inventory of the contents of the extra boxes. The analysis of these 3695 herbarium specimens clearly shows that it mainly consists of samples obtained by exchange (67.1%) especially within the Société Helvétique pour l"Échange des Plantes and the Societat Botànica Barcelonesa. Among the materials studied we found two specimens regarded as interesting from a taxonomical and/or nomenclatural point of view (isotypes of Silene holzmanii Heldr. ex Boiss. and of Arenaria minutiflora Loscos). Therefore, the main interest of the herbarium lies in the diversity of the geographical provenance of plants, which makes of this collection one of the first"pan-European herbaria" in Catalonia

Probing Supergravity Models with Indirect Experimental Signatures

We explore the one-loop electroweak radiative corrections in the context of the traditional minimal $SU(5)$ and the string-inspired $SU(5)\times U(1)$ supergravity models by calculating explicitly vacuum-polarization and vertex-correction contributions to the $\epsilon_1$ and $\epsilon_b$ parameters. We also include in this analysis the constraint from $b\rightarrow s\gamma$ whose inclusive branching ratio $B(b\rightarrow s\gamma)$ has been actually measured very recently by CLEO. We find that by combining these three most important indirect experimental signatures and using the most recent experimental values for them, $m_t\gtrsim 170 {\rm GeV}$ is excluded for $\mu>0$ in both the minimal $SU(5)$ supergravity and the no-scale $SU(5)\times U(1)$ supergravity. We also find that $m_t\gtrsim 175(185) {\rm GeV}$ is excluded for any sign of $\mu$ in the minimal ($SU(5)\times U(1)$) supergravity model.Comment: RevTeX 3.0, 16 Pages+4 figures(not included but available as a uuencoded file from [email protected]), SNUTP-94-9

On the Erasure and Regeneration of the Primordial Baryon Asymmetry by Sphalerons

We show that a cosmological baryon asymmetry generated at the GUT scale, which would be destroyed at lower temperatures by sphalerons and possible new B- or L-violating effects, can naturally be preserved by an asymmetry in the number of right-handed electrons. This results in a significant softening of previously derived baryogenesis-based constraints on the strength of exotic B- or L-violating interactions.Comment: 10 pp. LaTex (2 figures, included) UMN-TH-1201/9

Zeroing In On the Top Quark, LSP and Scalar Higgs Masses

We estimate the top quark, lightest sparticle (LSP) and scalar higgs masses within a supersymmetric grand unified framework in which $\tan\beta \simeq m_t/m_b$ and the electroweak symmetry is radiatively broken. The requirement that the calculated $b$ quark mass lie close to its measured value, together with the cosmological constraint $\Omega_{LSP} \approx 1$, fixes the top quark mass to be $m_t(m_t) \approx 170 \pm 15\ GeV$. The LSP (of bino purity $\stackrel{_>}{_\sim} 98\%)$ has mass $\sim 200 - 350\ GeV$. In the scalar higgs sector the CP-odd scalar mass $m_A \stackrel{_<}{_\sim} 220\ GeV$. With $m_A \stackrel{_>}{_\sim} M_Z$, as suggested by the decay $b \rightarrow s\gamma$, we find $M_Z \stackrel{_<}{_\sim} m_{h^0} (m_{H^0}) \stackrel{_<}{_\sim} 140 (220)\ GeV$ and $120\ GeV \stackrel{_<}{_\sim} m_{H^\pm} \stackrel{_<}{_\sim} 240\ GeV$.Comment: 14 pages in plain LaTeX, BA-93-25, PRL-TH-93/

From Rome to Angostura: a study of Simon Bolivar’s political thought based on his writings during the initial phases of the Independence process (first period, 1805-1813)

El presente texto pretende acercarse al pensamiento político de Simón Bolívar a través del análisis de sus principales documentos del período comprendido entre 1805 y 1819, así como del contexto en medio del que estos fueron producidos, labor que, si se extendiera a la totalidad de los mismos, difícilmente podría ser concluida en un corto lapso de tiempo y mucho menos con el fin de la publicación de un artículo como el que nos involucra en esta oportunidad. Para esta primera entrega, seguiremos a Simón Bolívar desde su nacimiento, formación y despuntar político, hasta ser elevado y reconocido como El Libertador, en medio de su apoteósica recepción en Caracas tras la exitosa Campaña Admirable, apenas unos meses antes de su estrepitosa caída y los años aciagos que siguieron a ella, tema que abordaremos en la segunda parte de este escrito; un recorrido por sus victorias y sus derrotas a lo largo de este período, las mismas que contribuyeron a formar su carácter y lo hicieron sobresalir entre sus compañeros de lucha por su abnegación y coraje.This article approaches the political thought of Simón Bolívar through an analysis of his most important documents written in the period 1805-1819, and of the context in which they were written. The article follows Bolívar’s life, from his birth, through his education and political success up to his achieving the status of the Liberator at his glorious reception in Caracas after the successful Admirable Campaign, just a few months before his spectacular fall from grace and the inglorious years that followed. The article traces his victories and defeats throughout this period, focusing on how they formed his character and contributed to his exaltation amongst his comrades for his self-sacrifice and courage

Carreras eclesiásticas y redes clientelares en la Castilla bajomedieval: la provisión de beneficios menores en el cabildo de la catedral de Burgos (1456-1470)

The nature and evolution of the lower social groups that constituted cathedral chapters is still an unknown aspect of the middle ages in Spain. This evidence has not prevented historiographical notice of the important role of the offices and benefices enjoyed by this large sector of the clergy in their ecclesiastical careers and in the composition of the fortunes of high status clerics. This article sheds light on the status of a large group of prebendaries in the cathedral chapter during the first stage of the episcopate of Luis de Acuña (1456-1495). It analyses the provision and exchange of minor ecclesiastical benefices, which constituted the first step in the chain of promotion of the cursus honorum of Burgos’s ecclesiastical men. Also studied is the role played by the bishop Luis de Acuña as a promoter of a social network among the clergy of the cathedral of Burgos.<br><br>La naturaleza y evolución de los grupos sociales inferiores que constituyeron los cabildos de las catedrales continúa siendo un aspecto poco conocido de la España medieval. Esta evidencia no ha impedido a la historiografía advertir el papel determinante que los oficios y beneficios disfrutados por este amplio sector del clero jugaron en las carreras eclesiásticas y en la configuración de las fortunas de los miembros capitulares de mayor rango. El presente artículo pretende arrojar luz sobre el estatus del numeroso grupo de los prebendados menores que componían la estructura del cabildo burgalés durante la primera mitad del episcopado de Luis de Acuña (1456-1495). Para ello se analiza el sistema de provisión y permutas de beneficios eclesiásticos menores; primer eslabón de importancia en la cadena de promociones que constituía el <em>cursus honorum</em> de los capitulares burgaleses. Además, se examina el protagonismo del Obispo Acuña como impulsor de una red clientelar entre el clero catedralicio

ϵb\epsilon_b Constraints on the Minimal SU(5)SU(5) and SU(5)×U(1)SU(5)\times U(1) Supergravity Models

We have performed a systematic analysis to compute the one-loop electroweak corrections to the Z->b b-bar vertex in terms of $\epsilon_b$ and $R_b$ in the context of the minimal $SU(5)$ and no-scale $SU(5)\times U(1)$ supergravity models. With the measured top mass, $m_t=174\pm 10^{+13}_{-12}$ \GeV , recently announced by CDF, we use the latest LEP data on $\epsilon_b$ and $R_b$ ($\equiv{\Gamma(Z->b b-bar)/{\Gamma(Z->hadrons)}}$) in order to constrain further the two models. We find that the present LEP data on $\epsilon_b$ and $R_b$ constrain the two models rather severely. Especially, the low-$\tan\beta$ region is constrained more severely. \tan\beta\lsim 2.5 $(4.0)$ is excluded by $\epsilon_b$ at $90\%$ C.~L. for m_t\gsim 170 $(180)$ \GeV in the minimal $SU(5)$ (no-scale $SU(5)\times U(1)$) supergravity. Even more stringent constraint comes from $R_b$. It excludes \tan\beta\lsim 4.0 at $90\%$ C.~L. for m_t\gsim 160 $(170)$ \GeV in the minimal $SU(5)$ (no-scale $SU(5)\times U(1)$) supergravity. We also find that the sign on $\mu$ in the two models can be determined from $\epsilon_b$ and $R_b$ at $90\%$ C.~L.Comment: RevTeX 3.0, 15 Pages+2 figures(not included but available as a uuencoded file from [email protected]), SNUTP-94-6

Constraints on Baryon-Nonconserving Yukawa Couplings in a Supersymmetric Theory

The 1-loop evolution of couplings in the minimal supersymmetric standard model, extended to include baryon nonconserving $(B\!\!\!/)$ operators through explicit $R$-parity violation, is considered keeping only $B\!\!\!/$ superpotential terms involving the maximum possible number of third generation superfields. If all retained Yukawa couplings $Y_i$ are required to remain in the perturbative domain $(Y_i < 1)$ upto the scale of gauge group unification, upper bounds ensue on the magnitudes of the $B\!\!\!/$ coupling strengths at the supersymmetry breaking scale, independent of the model of unification. They turn out to be similar to the corresponding fixed point values reached from a wide range of $Y_i$ (including all $Y_i$ greater than unity) at the unification scale. The coupled evolution of the top and $B\!\!\!/$ Yukawa couplings results in a reduction of the fixed point value of the former.Comment: PRL-TH-94/8 and TIFR/TH/94-7, 15 pages, LaTe

Squark and Slepton Mass Relations in Grand Unified Theories

In the minimal supersymmetric standard model, assuming universal scalar masses at large energies, there are four intragenerational relations between the masses of the squarks and sleptons for each light generation. In this paper we study the scalar mass relations which follow only from the assumption that at large energies there is a grand unified theory which leads to a significant prediction of the weak mixing angle. Two new intragenerational mass relations for each of the light generations are derived. In addition, a third mass relation is found which relates the Higgs masses, the masses of the third generation scalars , and the masses of the scalars of the lighter generations. Verification of a fourth mass relation, involvingonly the charged slepton masses, provides a signal for SO(10) unification.Comment: 29 pages, LateX, 2 uuencoded figures include