6,892 research outputs found
Oscillations of neutral B mesons systems
The oscillation phenomenon in the neutral B mesons systems is now well
established.
The motivations and principles of the measurements are given; then the most
recent results from the LEP experiments, the CDF collaboration at Fermilab and
the SLD collaboration at SLAC are reviewed.
The present world average of the \bd meson oscillation frequency is \dmd =
0.471 \pm 0.016 \ps and the lower limit on the \bs oscillation frequency is
\dms > 12.4 \ps at 95% CL.Comment: 9 page
Customs Unions And Foreign Investment: Theory And Evidence From Mercosur’s Auto Industry
This paper demonstrates how regional trade agreements (RTAs) can lead to both foreign direct investment expansion and relocation effects. These two effects, in return, impact the endogenous formation of RTAs. The investment expansion effect results from foreign firms’ ability to serve a larger market from a single facility. The relocation effect occurs due to the firms’ desire to move their initial plants from high-cost member countries to low-cost ones. The relocation effect can overwhelm the expansion effect for the high-cost members and lead to the collapse of socially efficient RTAs. The auto industry in Mercosur is a great example to study these phenomena. Argentina was worried that low-cost Brazil would attract all of the foreign investment and dominate both markets. To convince Argentina to agree to free trade in automobiles (and to Mercosur), the auto sectoral agreement included the Compensated Trade Clause (CTC) which requires each firm to balance its trade between these countries. This mitigates the relocation problem by forcing firms to produce some models in Argentina and entices the governments to sign the RTA..
Algunas notas sobre arqueología y colonialismo : la zona española del protectorado marroquí, 1912-1945
A lo largo de la primera mitad del siglo XX se
desarrollaron en el Norte de Marruecos y en el seno
de la administración conjunta hispano-marroquí
del Protectorado ejercido por España sobre dichos
territorios las estructuras de gestión del Patrimonio
Arqueológico de dicha Zona. En los párrafos
de este artículo abordaremos el paulatino proceso
de construcción de dichas estructuras, que marchó
en paralelo al desarrollo de los trabajos de investigación
de campo y, en buena medida, de forma
subsiguiente a los mismos.Through the several decades belonging to the
first half of the XXth Century, the territories of
North Marocco, placed under the Spanish Protectorate
since the Conference of Algeciras in 1906,
experienced the development of real public structures
devoted to the management of that area’s
Archaeological Heritage. We shall focus on this
phenomenon, which is closely related to the development
of archaeological research in itself as well
Superconducting cavity transducer for resonant gravitational radiation antennas
Parametric transducers, such as superconducting rf cavities, can boost the
bandwidth and sensitivity of the next generation resonant antennas, thanks to a
readily available technology. We have developed a fully coupled dynamic model
of the system "antenna--transducer" and worked out some estimates of
signal--to--noise ratio and the stability conditions in various experimental
configurations. We also show the design and the prototype of a rf cavity which,
together with a suitable read--out electronic, will be used as a test bench for
the parametric transducer.Comment: 7 pages, 3 eps figures. Presented at the 6th Amaldi Conference on
Gravitational Waves (2005). Accepted for publication in Journal of Physics:
Conference Serie
Acute Stress Eliminates Female Advantage in Detection of Ambiguous Negative Affect
The human stress response evolved to maximize an individual's probability of survival when threatened. The present study addressed whether physical danger modulates perception of an unrelated ambiguous threat and, if so, to what extent this response is sex-specific. The authors utilized a first-time tandem skydive as a stressor, which had been previously validated as producing a highly-controlled, genuinely stressful environment. In a counter-balanced within-subjects design, participants wore a virtual reality helmet to complete an emotion-identification task during the plane's ascent (stress condition) and in the laboratory (control condition). Participants were presented static male faces morphed between 20–80% aggression, which gradually emerged from degraded images. Using a binary forced-choice design, participants identified each ambiguous face as aggressive or neutral. Results showed that participants characterized emotion more rapidly under stress versus control conditions. Unexpectedly, the results also show that while women were more sensitive to affect ambiguity than men under control conditions, they exhibited a marked decrease in sensitivity equivalent to men while under stress
Structure Elucidation of Natural Products From Asteraceae by Modern NMR Techniques and Biomimetic Transformations of 11,13-Dihydroparthenolide.
Chemical analysis of root cultures of Tagetes patula (Asteraceae) provided the knowns 5-acetyl-4-hydroxy-2-isopropenyl-benzofuran, 5-(but-3-en-1-ynyl)-2,2\sp\prime-bithiophene and 5-(4-acetoxy-1 butynyl)-2,2\sp\prime-bithiophene. Their structures were elucidated by spectroscopic methods. Chemical analysis by capillary gas-liquid chromatography-mass spectrocscopy (GC/MS) of Parthenium argentatum (Guayule) provided the known sesquiterpene hydrocarbons 9,10-dihydroguajene, -copaene, alloaromandrene, isolongifolene, germacrene A or -elemene and -humulene. The known sesquiterpene esters guayulin A and B and the triterpenes argentatin A and B as well as two new cycloartenol-type triterpenes, 3- and 3-hydroargentatin B, were also isolated. The relative configuration, the conformation as well as the \sp1H and \sp{13}C NMR resonance assignments of the two new triterpenes were established by 2D and multipulse NMR techniques. Hydrolysis of guayulin A yielded desacylguayulin A, a stereochemical study of which was performed using modern NMR techniques. Chemical analysis of Baccharis salicina (Asteraceae) yielded the known antitumor flavone centaureidin and two new guaianolides, bacchariolides A and B. Their structures were elucidated by spectroscopic methods. Biomimetic-type reactions of the sesquiterpene lactone 11,13-dihydroparthenolide involved the following transformations: (1) BF\sb3-mediated rearrangement of the germacrolide 4(5)-epoxide to produce a xanthanolide and three cis-guaianolides. (2) m-Chloroperoxybenzoic acid mediated oxidation-rearrangements of a guaianolide 1(10)-ene to produce a xanthanolide, a trans-epoxy-guaianolide, two cis-epoxy-guaianolides and a cyclobutane-type sesquiterpene lactone. (3) BF\sb3-catalyzed rearrangement of a guaianolide 1(10)--epoxide to give a cis-eudesmanolide, a trans-guaianolide, and two cis-guaianolides. The results and proposed mechanisms of these reaction sequences as well as the detailed structure elucidation of the transformation products are described
El Camino de Leloir
originalFil: Parodi, Armando J..3 páginas en papelLFL-CD-OTROS. Escritos de OtrosUnidad documental simpl
Los Trabajos de Leloir
Contiene:
I. Trabajos Publicados: listado bibliográfico de la Producción Científica del Dr. Leloir.
II. Obra Selecta: análisis realizado por el Dr. Armando J. Parodi con 31 trabajos considerados los más relevantes de Leloir.originalFil: Parodi, Armando J..15 páginas en papelLFL-CD-OTROS. Escritos de OtrosUnidad documental simpl
La Fundación Instituto Leloir -Instituto de Investigaciones Bioquímicas Fundación Campomar (FIL-IIB-FC)- como motor del desarrollo de la investigación en bioquímica en Argentina
El propósito de este escrito es mostrar como tanto del núcleo inicial de investigadores en el Instituto de Investigaciones Bioquímicas Fundación Campomar como de investigadores que se incorporaron posteriormente a él se originaron varios centros de investigación en la misma disciplina en nuestro país.originalFil: Parodi, Armando J.. Fundación Instituto Leloir; Argentina5 páginas en papelLFL-CD-OTROS. Escritos de OtrosUnidad documental simpl
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