Focuses on the Buber-Rosenzweig translation of the bible. Need for biblical translation that is customary and familiar with the 20th century generation; Reflection of the links between German culture and Jewish tradition; Traditional Jewish sources; Influence of early German Romanticism.
The chicken homebox containing gene, CdxA (formerly CHox-cad), was previously shown to be expressed during gastrulation. Localization of CdxA transcripts by in situ hybridization to tissue sections revealed that, during gastrulation, expression of this gene exhibits a posterior localization along the primitive streak. The transcripts are localized to epiblast cells in the vicinity of the primitive streak, to cells of the primitive streak itself and in the definitive endoderm as it replaces the hypoblast. In order to study in greater detail the pattern of expression of the CdxA gene during gastrulation, we expressed the full-length CdxA protein as a fusion protein in E. coli and generated monoclonal antibodies against it. Chicken embryos at different stages of gastrulation were processed for whole-mount immunohistochemical localization of the protein using anti-CdxA antibodies. Once the pattern of expression in the whole embryo was determined, the same embryos were sectioned to determine the identity of the cells expressing the CdxA protein. Detailed analysis of the CdxA protein in embryos, from the onset of primitive streak formation to the beginning of the tail bud stage (stages 2 to 10), has shown different patterns of expression during primitive streak elongation and regression. The CdxA protein is initially detected at the posterior marginal zone and the expression moves rostrally into the primitive streak during mid-streak stages. As the primitive streak elongates, the CdxA stripe of expression moves anteriorly. By definitive streak stages, the CdxA stripe of expression delineates a position along the anterior-posterior axis in the primitive streak. CdxA, like its Drosophila homologue cad, is expressed during gastrulation in a stripe localized to the posterior region of the embryo. These observations suggest that CdxA as a homebox gene may be part of a regulatory network coupled to axial determination during gastrulation in the early chick embryo.
This paper suggests that the constraints to small business development are likely to vary across the firm's life cycle. In addition, small businesses operating in peripheral areas are likely to face growth constraints arising from their location. On the basis of survey evidence from 100 small (owner-managed) firms operating in both peripheral and central locations in Israel, the probability of encountering a constraint (capital, marketing or bureaucratic) is then estimated. This probability is estimated for two points in the firms' development trajectory: the start-up stage and the stage of sustained operation. The results suggest that at the start-up stage the personal attributes of the entrepreneur serve to mitigate the odds of encountering a constraint while firm size increases the chances. At the operating stage, the personal characteristics of the owner and the form of economic activity are found to be influential. The conclusions point to the high opportunity costs associated with small firms in peripheral areas and to the role of firm size in mitigating the effects of finance constraints over the life cycle. The broad policy implications of these findings are outlined.
The construction of covalently self-assembled second-order nonlinear optical (NLO) Materials containing stilbazole or alkynyl-type high-β chromophores acentrically organized on inorganic oxide substrates is discussed. These structurally different chromophores exhibit differing packing densities on the surface when introduced under the same reaction conditions. In the stilbazolium chromophores, ion-exchange of the chloride counter-anion with very large anionie organic dyes results in appreciably enhanced second harmonic generation (SHG) efficiency. The frequency-dependent SHG response for self-assembled Monolayers derived from the alkynyl-type chromophore was also investigated. The linear absorption spectra exhibit two maxima in the visible region which are assigned to electronically isolated chromophores (480 nm) and aggregated species (540 nm). The dispersion of the second-order NLO coefficient reveals that both microstructures are NLO-active. The origin of the SHG response from both assemblies is discussed.
We discuss a generalized dynamic mean-field method combining the advantages of explicit pair correlations and of configuration interaction. The approximate dynamical method, which we call time-dependent self-consistent-field configuration interaction (TDSCF2-CI), is constructed by including N(N-1)/2 TDSCF2 configurations. In each configuration a given pair of N coupled modes is directly (not in the mean-field approach) correlated; the N(N-1)/2 configurations include all such choices of pairs. As such, it has both the usual advantages of TDSCF and improvements due to some inclusion of correlations (exact results for any two-mode problem, improved descriptions of dynamical corrections, and greater accuracy). A three-mode model Hamiltonian is analyzed using five approximate treatments, i.e., the usual TDSCF, the three TDSCF2 forms, and the TDSCF2-CI one. The quantities for comparison with the exact results include the decay P(t) of the initial state, the time dependencies of the energies e (i) of individual modes, and the overlap S (t) of the corresponding approximate wave function with the exact one. We find, indeed, that explicit inclusion of pair correlations improves the description of the quantum dynamics of the system.
A theoretical investigation of the photodissociation dynamics of (HCI)2 at 193 nm is presented. Prior to excitation, the cluster is taken to be in its rotation-vibration ground state. A quantal description of this six-dimensional wave function is computed using diffusion quantum Monte Carlo (DQMC). The photodissociation dynamics are simulated by classical trajectories in which the molecule undergoes vertical excitation to an electronic state that is repulsive along one of the HCI stretch coordinates. The initial conditions for these trajectories are sampled according to the Wigner function which was obtained from the DQMC wave function. In a significant fraction of these trajectories, there is a reactive collision in which the H atom interacts with the H'Cl' molecule to form HCI'. Of the remaining collisions, most are nonreactive, but a small number lead to H-2 formation. The trajectories in which an exchange reaction occurs result typically in formation of HCI' molecules that are rotationally and vibrationally hotter and in H atoms with lower kinetic energies than are found in the nonreactive trajectories. Resonances, in which the H atom undergoes multiple collisions with Cl and H'Cl', are observed in all three classes of trajectories. The above results indicate that this is a rich system for the study of photoinduced chemical reactivity in hydrogen-bonded clusters.
The reaction between an O(3P) atom and a hydrocarbon molecule weakly bound to an argon atom was studied by classical trajectory simulations. The results are compared to those obtained for the reaction of a free hydrocarbon. A simplistic model system was constructed in which the hydrocarbon was represented as a pseudodiatomic molecule. Although simple, the model reproduced correctly the internal energy distribution in the OH produced in the reaction of the free species. It was found that the OH, produced from the reaction of the van der Waals complex, emerges with less internal energy and less translational energy than the OH from the monomeric process. In the case of the complexed reagents, the collision complex lifetime is longer and the oxygen explores portions of the potential energy surface that are not available in the monomeric reaction.
A theoretical study is presented on the photodissociation dynamics of Cl2 in crystalline xenon at 100 K, and within a range of pressure between 0 and 100 kbar. Temperature/pressure ensemble molecular dynamics simulations were carried out. The potentials used were accurate enough to reproduce the experimental equation of state of solid xenon. The results show that the photodissociation quantum yield varies strongly with pressure, falling from 30% at zero pressure, to 2% at 12.5 kbar, and 0% at higher pressures. These yields are in good agreement with experimental measurements. This behavior is found to be due to the strong effect of pressure on the librational (rotational) amplitudes of the Cl2 molecule and to the sharp dependence of the photodissociation yield on the molecular orientation in the reagent cage.
An electrochem. pretreated glassy carbon electrode (GCE) modified with an aza crown ether, 8,9,17,18-dibenzo-1,7-dioxa-10,13,16-triazacyclooctadecane (DDTC), has been used for the very sensitive and selective anal. of trace amts. of gold(III). A detection limit of 4.2 × 10-10 M was obtained by applying anodic stripping voltammetry. The parameters that affect the sensitivity and possible interferences by other ions have been examd. in detail. The modified electrodes exhibit high stability and, therefore, have been used repeatedly without mech. regeneration. Finally, the method has been successfully applied to det. gold traces in a geol. sample. [on SciFinder(R)]
Selective detn. of ultra low levels of mercury (<10-12M) is described using a glassy carbon electrode spin coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222). The electrode was used for the detn. of mercury in sea water by anodic stripping voltammetry. [on SciFinder(R)]
Selective detn. of ultra low levels of mercury (<10-12M) is described using a glassy carbon electrode spin coated with 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix-222). The electrode was used for the detn. of mercury in sea water by anodic stripping voltammetry. [on SciFinder(R)]
