Specific synthesis of 1,2- and 1,3-dialkylidenecycloheptanes by [3+2+2] cyclization of alkenyl Fischer carbene complexes and allenes

The 1,2- and 1,3-dialkylidenecycloheptane rings are specifically assembled from chromium alkenyl Fischer carbene complexes and allenes via [3+2+2] cyclization reactions. The former cycloadducts are obtained when the cyclization is performed in the presence of 1 equiv of [Ni(cod)2], while the [Rh(cod)Cl]2-catalyzed cyclization leads to the latter cycloadducts.     

Mapping of the <Superscript>12</Superscript>C* states via the <Superscript>10</Superscript>B(<Superscript>3</Superscript>He,pααα) reaction

We have studied ¹²C in full kinematics via the ¹⁰B(³He,pααα) reaction at an energy of 2.45 MeV. In our data we have identified states in ¹²C from the ground state up to about 18 MeV, with spins ranging from 0 to 4. Due to the very good resolution, we are able to determine properties of these ¹²C resonances, such as their energy, width, and spin. In this contribution preliminary results from the ongoing analysis are presented. Main focus on the precise determination of the breakup spectra for all resonances.     

Evidence for a new low-lying resonance state in 7He

Low-lying resonance states in 7He(6He+n), formed after fragmentation reactions of a 227 MeV/nucleon 8He beam on a carbon target, have been studied. Coincidences between 6He nuclei and neutrons, corresponding to the one-neutron knockout channel in 8He, were selected. The relative energy spectrum in the 6He+n system shows a structure, which is interpreted as the 7He ( Ipi = 3/2(-)) ground state, unbound with 0.43(2) MeV relative to the 6He+n system and a width of Gamma = 0.15(8) MeV overlapping with an excited ( Ipi = 1/2(-)) state observed at 1.0(1) MeV with a width of Gamma = 0.75(8) MeV.     

Horwich on Natural and Non-Natural Meaning

Paul Horwich’s Use Theory of Meaning (UTM) depends on his rejection of Paul Grice’s distinction between natural and non-natural meaning and his Univocality of Meaning Thesis, as he wishes to deflate the meaning-relation to usage. Horwich’s programme of deflating the meaning-relation (i.e. how words, sentences, etc., acquire meaning) to some basic regularity of usage cannot be carried through if the meaning-relation depends on the minds of users. Here, I first give a somewhat detailed account of the distinction between natural and non-natural meaning in order to set the stage for Horwich’s critique of it. I then present Horwich’s critique of the distinction and show how that rejection accords with his overall view of meaning as use. Horwich’s rejection of the distinction between natural and non-natural meaning, I argue in the last section, is ill founded, and because UTM depends on this rejection, UTM is stillborn.     

Stable and superstable customer policies in queues with balking and priority options

We discuss decision-making in queueing systems where individual customers have one or both of two options: (1) option to join or balk, (2) option to choose priority through a payment made on arrival. Each customer's objective is to maximize the expected net gain, defined as 0 if he balks, and as R - b - hE(W) if he joins, where R is his reward, b is his payment, h is his unit time waiting loss, and E(W) is his expected waiting time. The models considered are: (A) a GI/M/s/N queue with either FIFO or LIFO rule, and a balking option, (B) an M/M/s/N queue with a priority option, (C) an M/M/s/N queue with balking and priority options. Rational customers will limit their choice to a certain subset of actions, derived by considering the actions of other customers. When the subset consists of just one action we call it optimal. The analysis focuses on policies, that is, decision rules selecting an action as a function of arrival state (customers in system), R and h. Stable (self-sustaining) and superstable (optimal) policies are of special interest. A stable policy may not exist and it is not necessarily unique. In model A a superstable policy exists except, possibly, for N = ∞ with LIFO rule. For model B we give necessary and sufficient conditions that a policy is stable and induces either FIFO or LIFO service order. Similar results are derived in special cases of model C.     

Kinematic identification of the \betat branch in the decay of 11Li

The $ \beta$ -delayed ⁸ Li + t branch of the ¹¹Li decay was identified via kinematical analysis of the charged particles observed in coincidence. The back-to-back events observed in a narrow angular acceptance were compared to a Monte Carlo simulation. The ⁸ Li + t sum energy spectrum was fitted assuming that the decay occurs through an intermediate state in ¹¹Be . The resulting energy centroid and full-width half maximum for the intermediate state are 18.35(30)MeV and 1.5(4)MeV, respectively. The $ \beta$ -delayed ⁸ Li + t branching ratio obtained from the coincidence spectrum, BR _t = 0.93(8)×10^-4 , is in agreement with previous measurements but more precise.     

On the liquid junction potential for the determination of equilibrium constants by means of the potentiometric technique without constant ionic strength

A modified method for the calculation of liquid junction potentials based on the Henderson equation is proposed. The estimation of the activity coefficients and the conductivities is performed by means of the Modified Bromley Methodology [G. Borge, R. Castaño, M.P. Carril, M.S. Corbillón, J.M. Madariaga, Fluid Phase Equilibria 121 (1996) 85–98;G. Borge, N. Etxebarria, L.A. Fernández, M.A. Olazabal, J.M. Madariaga, Fluid Phase Equilibria 121 (1996) 99–109.] and the Extended Falkenhagen Equation [A. De Diego, Conductivity of concentrated electrolytic solutions: study of the dependence with concentration and temperature, Ph.D. Thesis, University of the Basque Country, Bilbao, 1996.]. The efficiency of the method has been tested in potentiometric titrations without constant ionic strength. Its applicability to potentiometric titrations with constant ionic strength is also discussed.