Left-Associative Grammar: An informal outline

The surface structures of natural language are linear. When we utter or understand a sentence, we process it word by word, starting at the beginning. But the associated semantic structures are hierarchical, expressed in terms of trees or set-theoretic relations. The correlation between linear syntax and hierarchical semantics is investigated in Left-Associative Grammar and the associated NEWCAT parsing algorithm. This paper gives a general outline of the linguistic theory. The formal algebraic and automata theoretic definitions will be presented in a second paper (Hausser, forthcoming), to appear in next issue of CaT.     

Graphit einlagerungsverbindungen mit thallium(III) bromid

Intercalation compounds of graphite with TlBr₃ were prepared by the following procedures. Method I: graphite and TlBr were reacted with liquid bromine (which oxidizes TlBr to TlBr₃). After refluxing this mixture for 2–4 days, the bromine was filtrated off, and then the samples were washed with a solution of methanol containing bromine in order to remove any thallium bromide excess. Method II: mixtures of graphite, TlBr and bromine were heated in sealed tubes for definite times at pre-selected temperatures. After heating, the samples were separated as described before. The conditions of these intercalating experiments and results of analyses are given in Table 1.The results shown in this table confirm that TlBr₃ can be intercalated in graphite in substantial quantities, in spite of the fact that genuine TlBr₃ is a nonexisting compound. TlBr₃-graphite is a ternary compound analogous to AlBr₃-graphite [2] or GaBr₃-graphite[3]. Some of the co-intercalated bromine could be removed by evacuation, but the ratio $\text{Br}\text{Tl}$ obtained was never less than 3.3. Like other metal halide graphite compounds [1,8] TlBr₃-graphite may be given the formula: C_n⁺[TlBr₄^?]·2TlBr₃.All compounds shown in Table 1 are of the 2nd stage type. The I_c-values vary somewhat with the amount of bromine. The distance of two carbon layers separated by intercalated TlBr₃ was found to be 1005 pm (compound 6), as compared to be 1000 pm for C₂₄AlBr_3.3[2]. It is, therefore, assumed that TlBr₃, like AlBr₃, is intercalated in form of sheets made up of Tl₂Br₆ molecules.In contrast to TlBr₃ which exists only in liquid bromine and decomposes immediately as soon as the bromine is removed, the intercalated TlBr₃ is still stable at 150°C. Obviously TlBr₃ is stabilized by intercalation.By treating a 2nd stage TlBr₃-graphite with TlCl₃ in refluxing SOCl₂ a compound with the composition C_12.5TlCl_1.8Br_1.6 (Table 3) was obtained. As X-ray studies confirmed this compound has a structure of stage 1 made up of alternating TlBr₃ and TlCl₃ layers separated by a carbon sheet.The resemblances as well as the differences between TlBr₃-graphite and AlBr₃-graphite or GaBr₃-graphite are discussed.     

Oscillatory insulin secretion after pancreas transplant

In vivo studies of beta-cell secretory function have demonstrated the existence of rapid insulin oscillations of small amplitude recurring every 8-15 min in normal subjects. This study evaluated the effects of pancreas transplant on rapid insulin oscillations. Samples for glucose, insulin, and C-peptide were drawn during constant glucose infusion at 2-min intervals for 90 min from six successful Px patients with type I diabetes mellitus, from six normal nondiabetic control subjects, and from three Kx subjects. A computerized algorithm (ULTRA) was used for pulse detection. In the Px group, the average insulin pulse period was significantly shorter than in both the control and Kx groups (Px 8.1 +/- 0.5, control 12.5 +/- 0.7, Kx 12.4 +/- 0.5 min, P < 0.0005). By contrast, the C-peptide pulse periods (Px 16.8 +/- 2.3, control 14.7 +/- 1.2, Kx 15.3 +/- 1.5 min) were similar in the three groups. Spectral analysis confirmed that the frequency of the insulin pulses was increased in the Px group. The absolute amplitude of the insulin pulses was greater in the Px group (P < 0.001) while the amplitude of the C-peptide pulses did not differ between the groups. Cross-correlation analysis demonstrated maximal correlation coefficients at a lag of 0 min between insulin and C-peptide (control r = 0.33, P < 0.0001; Kx r = 0.17, P = 0.06) and between insulin and glucose (control r = 0.21, P < 0.001; Kx r = 0.20, P < 0.02) in the control and Kx groups, respectively, whereas no significant correlations were observed at any lag in the Px group.(ABSTRACT TRUNCATED AT 250 WORDS)     

The anatomy and the MRI anatomy of the interhemispheric cerebral commissures

Correlation of myelin-stained or cryotomic sections of human brain with inversion-recovery MR images can display the cerebral commissures as white-matter tracts (in hypersignal on MRI), crossing the mid-line. MRI shows routinely in three orthogonal planes a) the corpus callosum stretched above the supra-tentorial ventricles, it's four portions (rostrum, genu, body and splenium) and connections with the Deep Grey Nuclei b) the fornix, intralimbic commissure joining anteriorly the mammillary bodies (through it's columns) to the alveus posteriorly and inferiorly (via it's two crura), arcing around the thalamus and lying over the hippocampus and the dentate gyrus as shown on the frontal sections c) the anterior commissure, white-matter tract connecting the two temporal lobes. In axial view, the anterior commissure has the shape of bicycle handlebars, coursing posteriorly, inferiorly and laterally behind the head of the caudate nucleus and passes into the lateral nucleus of the globus pallidus into the inferior and middle temporal gyri. Because the anterior commissure is easily recognisable in all planes, it's appears to be a important landmark for identification of the lateral and medial nuclei of the globus pallidus on axial and sagittal planes d) at least, the posterior commissure, anterior margin of the pineal region, closely related to the superior colliculi, acquire a major importance in the AC-PC line delineation becoming a reference landmark for stereotatical procedures.     

Rutherford backscattering — A tool for quantification of the results of PIXE analysis of single hair strands

As shown in a companion paper the geometrical diameter of a hair strand is an important parameter for quantification of its trace element content after PIXE analysis. By analysing Rutherford backscattered protons simultaneously with PIXE analysis a reliable estimate of the hair diameter can be obtained. In this work the hypothesis that there exists a linearity between the geometrical diameter and the number of backscattered protons in a certain energy interval is developed, discussed and experimentally verified.     

Ternary rare earth transition metal phosphides II. Synthesis and structure determination of Ho20Ni66P43

Single crystals of Ho₂₀Ni₆₆P₄₃ were obtained by reacting the elemental components at high temperature. The unit cell is hexagonal with lattice constants $\text{a}\text{= 23.095 (7)}\text{A}\text{?}$, $\text{c}\text{= 3.742 (4)}\text{A}\text{?}$; the space group is P6₃/m with Z = 1. The structure has been determined from X-ray data to a final R value of 0.054 for 850 reflections (I > 1 σ (I)). This structure is of a new type and belongs to the structural family of Zr₂Fe₁₂P₇- and Zr₆Ni₂₀P₁₃-types. The coordination polyhedra and structural comparison with closely related structure-types are discussed.