Odd-even oscillations of SHG efficiencies in twin NLO chromophores

Twin NLO chromophores having two azobenzene units linked by a flexible polymethylene spacer of varying lengths are shown to exhibit odd-even oscillations in their second harmonic generation (SHG) efficiencies, when measured in the powder form. These twin systems were designed to also exhibit liquid cystallinity, and indeed most of them do exhibit a nematic mesophase. The anticipated odd-even oscillations, in both their isotropization transition temperatures (Ti) and isotropization entropies (Delta Si), were also observed. The odd-even oscillation of the SHG efficiencies has been ascribed to a more effective cancellation of mesogenic dipoles in the even twins as compared to their odd counterparts, due to a preferred centrosymmetric packing in the former case. Based on the behaviour of these twin chromophoric molecules, it may be anticipated that such odd-even oscillations will also be observed in the analogous main chain NLO polymers.

Two-channel Kondo physics in odd impurity chains

We study odd-membered chains of spin-1/2 impurities, with each end connected to its own metallic lead. For antiferromagnetic exchange coupling, universal two-channel Kondo (2CK) physics is shown to arise at low energies. Two overscreening mechanisms are found to occur depending on coupling strength, with distinct signatures in physical properties. For strong interimpurity coupling, a residual chain spin-1/2 moment experiences a renormalized effective coupling to the leads, while in the weak-coupling regime, Kondo coupling is mediated via incipient single-channel Kondo singlet formation. We also investigate models in which the leads are tunnel-coupled to the impurity chain, permitting variable dot filling under applied gate voltages. Effective low-energy models for each regime of filling are derived, and for even fillings where the chain ground state is a spin singlet, an orbital 2CK effect is found to be operative. Provided mirror symmetry is preserved, 2CK physics is shown to be wholly robust to variable dot filling; in particular, the single-particle spectrum at the Fermi level, and hence the low-temperature zero-bias conductance, is always pinned to half-unitarity. We derive a Friedel-Luttinger sum rule and from it show that, in contrast to a Fermi liquid, the Luttinger integral is nonzero and determined solely by the ``excess'' dot charge as controlled by gate voltage. The relevance of the work to real quantum dot devices, where interlead charge-transfer processes fatal to 2CK physics are present, is also discussed. Physical arguments and numerical renormalization-group techniques are used to obtain a detailed understanding of these problems.

Odd-even effect in the elastic modulii of alpha,omega-Alkanedicarboxylic acids

Nanoindentation studies on alpha,omega-alkanedicarboxylic acids reveal that the elastic modulus, E, shows an odd-even alternation in exactly the same manner as the melting temperature, T-m. The results are consistent with the hypothesis that the strained molecular conformations in the odd diacids are the reasons for these alternations in T-m. The same packing features that lower T-m in the odd acids lead to easy accommodation of the deformation during nanoindentation and hence their low E.

On existence of periodic solutions for stable interval plants with odd, sector type nonlinearities

In several systems, the physical parameters of the system vary over time or operating points. A popular way of representing such plants with structured or parametric uncertainties is by means of interval polynomials. However, ensuring the stability of such systems is a robust control problem. Fortunately, Kharitonov's theorem enables the analysis of such interval plants and also provides tools for design of robust controllers in such cases. The present paper considers one such case, where the interval plant is connected with a timeinvariant, static, odd, sector type nonlinearity in its feedback path. This paper provides necessary conditions for the existence of self sustaining periodic oscillations in such interval plants, and indicates a possible design algorithm to avoid such periodic solutions or limit cycles. The describing function technique is used to approximate the nonlinearity and subsequently arrive at the results. Furthermore, the value set approach, along with Mikhailov conditions, are resorted to in providing graphical techniques for the derivation of the conditions and subsequent design algorithm of the controller.

The knight of sugar industry: T. S. Venkatraman (1884-1963)

Tiruvadi Sambasiva Venkatraman (TSV) was a plant breeder. In response to a call from Pundit Madan Mohan Malaviya, he made it his mission to develop high-yielding varieties of sugarcane for manufacturing sugar and making it available as a sweetening agent and an energy source for the malnourished children of India. Using Saccharum officinarum, then under cultivation in India, as the female parent, he artificially fertilized it with pollen from S. barberi, which grew wild in Coimbatore. After 4-5 recurrent backcrossings of S. officinarum Chi wild Sorghum spontaneum with S. officinarum as the female parent, TSV selected the `rare' interspecies hybrid cane varieties that resembled sugarcane and had approximately 2.5 cm thick juicy stems containing 16-18% sucrose - nearly 35 times more than what occurred in parent stocks. The hybrid canes matured quickly, were resistant to waterlogging, drought, and to the red-rot disease caused by Glomerella tucumanensis (Sordariomycetes: Glomerellaceae), and to the sereh-virus disease. Most importantly, they were amenable for propagation using stem cuttings. In recognition of the development of high-yielding sugarcane varieties, TSV was conferred the titles Rao Bahadur, Rao Sahib, and Sir by the British Government, and Padma Bhushan by the Republic of India. In the next few decades, consequent to TSV's work, India turned into the second largest sugar producer in the world, after Brazil. The hybrid sugarcane varieties developed are the foundational stocks for new sugarcane x bamboo hybrids, and for possible resistance to Puccinia megalocephala (Pucciniomycetes: Pucciniaceae) and Ustilago scitaminea (Ustilaginomycetes: Ustilaginaceae) using molecular techniques.

Succinate esters: odd-even effects in melting points

Dialkyl succinates show a pattern of alternating behavior in their melting points, as the number of C atoms in the alkane side chain increases, unlike in the dialkyl oxalates Joseph et al. (2011). Acta Cryst. B67, 525-534]. Dialkyl succinates with odd numbers of C atoms in the alkyl side chain show higher melting points than the immediately adjacent analogues with even numbers. The crystal structures and their molecular packing have been analyzed for a series of dialkyl succinates with 1 - 4 C atoms in the alkyl side chain. The energy difference (Delta E) between the optimized and observed molecular conformations, density, Kitaigorodskii packing index (KPI) and C-H center dot center dot center dot O interactions are considered to rationalize this behavior. In contrast to the dialkyl oxalates where a larger number of moderately strong C-H center dot center dot center dot O interactions were characteristic of oxalates with elevated melting points, here the molecular packing and the density play a major role in raising the melting point. On moving from oxalate to succinate esters the introduction of the C2 spacer adds two activated H atoms to the asymmetric unit, resulting in the formation of stronger C-H center dot center dot center dot O hydrogen bonds in all succinates. As a result the crystallinity of long-chain alkyl substituted esters improves enormously in the presence of hydrogen bonds from activated donors.

Vocación de poder : los abogados porteños a través de las colaciones de grado. 1884-1919

Resumen: El artículo trata sobre la formación de una fracción de la elite dirigente porteña en el paso del siglo xix al xx. La carrera de derecho siempre estuvo ligada al poder político y a la formación de la clase dirigente porteña. A través de los discursos de colación de grados de los doctores en jurisprudencia se busca indagar en los aspectos que los propios actores rescataban de su formación académica y su función social. Esta mirada tiene como objetivo destacar el rol de la Facultad de Derecho y Ciencias Sociales de la Universidad de Buenos Aires como canal de acceso privilegiado a la clase dirigente. Al tiempo se intenta observar como la preparación brindada en sus aulas no buscaba necesariamente la formación para el desempeño de la profesión de abogados sino que estaba orientada a la formación de dirigentes políticos.

Discurso y praxis contra el fraude : consideraciones sobre la política reformista de Roberto M. Ortiz (1938-1940)

Resumen: El objetivo de este trabajo es analizar la estrategia política del presidente Roberto M. Ortiz durante el período en actividad (1938-1940) para combatir el fraude electoral y normalizar las prácticas electorales e institucionalidad democrática de la Argentina de fines de los años treinta. Se presume que el presidente orientó su proyecto político de una manera aperturista y de diálogo sincero con la Unión Cívica Radical (UCR). Para ello promovió dos estrategias claras: lograr el apoyo de los sectores liberales del Ejército, e intervenir las provincias con prácticas fraudulentas. Su política contra el fraude provocó una situación inédita de erosión de la coalición de partidos oficialistas, base de sustentación del Poder Ejecutivo. Sin apoyo partidario, Ortiz quedó aislado y en clara confrontación con el Senado, dominado por grupos conservadores.

Guia de obras de Oscar Niemeyer : Brasília 50 anos

Apresenta informações precisas e primorosamente ilustradas sobre as obras mais importantes de Niemeyer presentes na capital do país, Brasília.

[Discurso do Deputado Oscar Corrêa : Sessão da Câmara dos Deputados de 08 de setembro de 1965]

Critica os serviços prestados pelas companhias aéreas, que agem como forças contrárias à consolidação de Brasília. Cita especialmente a deficiência do transporte aéreo entre a Capital Federal e Belo Horizonte.

[Discurso do Deputado Oscar Corrêa : Sessão da Câmara dos Deputados do dia 02 de maio de 1960]

Discurso proferido durante a 1ª Sessão da Câmara dos Deputados na nova capital do país. Descreve a falta de condições materiais e políticas para o pleno funcionamento do Congresso Nacional e do Poder Judiciário na nova capital.

Reproducción de documentación perteneciente a Miguel José Garmendia Aldaz, Asesor Jurídico y Secretario Particular del Consejero de Gobernación del Gobierno Vasco durante la Guerra en el Norte, y Mayor Jefe de la Demarcación de Fronteras en Cataluña a partir de octubre de 1938, y en enero de 1939 Delegado de Orden Público adscrito a la Comandancia Militar de Figueras.

Fecha: 10-10-1936/31-1-1939 / Unidad de instalación: Carpeta 25 - Expediente 21 / Nº de pág.: 33 (28 mecanografiadas, 5 manuscritas)

Copia de una Carta de Alberto Onaindia a su hermano Domingo en la que el primero informa al último de la labor espiritual realizada en la Prisión del Carmelo de Begoña entre el 25 de julio de 1937 hasta abril de 1938.

Fecha: s.f. (>1970 copia) / Unidad de instalación: Carpeta 45 - Expediente 2-17 / Nº de pág.: 2 (mecanografiadas)