Showing papers by "University of Erlangen-Nuremberg published in 1985"

Three-dimensional imaging by a microscope

Abstract: In transmission microscopy, many objects are three dimensional, that is, they are thicker than the depth of focus of the imaging system. The three-dimensional (3-D) image-intensity distribution consists of a series of two-dimensional images (optical slices) with different parts of the object in focus. First, we deal with the fundamental limitations of 3-D imaging with classical optical systems. Second, a transfer theory of 3-D image formation is derived that relates the 3-D object (complex index of refraction) to the 3-D image intensity distribution in first-order Born approximation. This theory applies to weak objects that do not scatter much light. Since, in a microscope, the illumination is neither coherent nor completely incoherent, a theory for partially coherent light is needed, but in this case the object phase distribution and the absorptive parts of the object play different roles. Finally, some experimental results are presented.

X-ray structural analyses of organolithium compounds

Abstract: Publisher Summary This chapter discusses the X-ray structural analyses of organolithium compounds. Lithium compounds, perhaps the most widely used organometallic synthetic intermediates, have fascinating structures. Nevertheless, organic chemistry textbooks often treat organolithium compounds merely as “carbanions” or as monomers. The chemical behavior of lithium compounds cannot be understood without the knowledge of the structures, the degree of aggregation, and the extent and nature of solvation. “Terminally bonded” organolithium compounds afford, in principle, the simplest examples of lithium–carbon σ–bonds. This class comprises lithium compounds with a single contact between lithium and a carbon atom. The dimer of lithiobicyclo butane, and of lithiodimethylsulfide, illustrates the bridging between sp 3 -hybridized carbon atoms while phenyllithium exemplifies bridging between sp 2 carbon atoms. A few organolithium compounds crystallize in aggregates with more than four subunits. Such compounds, derived from substituted acetylenic substrates (excluding simple acetylides), form oligomeric structures involving bridging lithium atoms and possible interactions of the lithium atoms with acetylenic π system. The benzophenonedilithium compound 50, formed by the reduction of benzophenone with lithium metal, crystallizes as a dimer. A large number of mixed-metal organometallic compounds have been prepared in which the hydrocarbon ligands bridge the lithium and the other metal atoms. A number of lithium/transition-metal compounds involving metal–metal multiple bonds as well as lithium–alkyl group interactions have been structurally characterized. The structure of lithium compounds without lithium–carbon bonds summarizes the structures of some lithium compounds that do not involve Li–C contacts.

Pain-related electrical potentials of the human nasal mucosa elicited by chemical stimulation.

Abstract: 1. (1) For the first time a non-invasive method was employed to record pain-related electrical potentials from the human respiratory nasal mucosa. 2. (2) Gaseous stimulants at painful concentrations were presented by the newly developed stimulating device. 3. (3) The amplitudes of the potentials were found correlated (a) with concentrations of the stimulants, and (b) with subjective estimations of pain intensity. 4. (4) The local anesthetic tetracaine hydrochloride, and also a systemically administered analgesic drug pentazocine given prior to painful stimulation decreased the amplitude of the negative potentials. 5. (5) The peripheral response was interpreted as a summated receptor potential from chemical nociceptors. It is thought to be analogous to the electro-olfactogram. This non-invasive technique of stimulation and recording offers an objective and quantitative measure related to pain sensations and their inhibition by analgesic drugs.

A quantitative test for xerostomia. The saxon test, an oral equivalent of the schirmer test

Abstract: We describe a simple, reproducible, and low-cost test for xerostomia, which involves chewing on a folded sterile sponge for 2 minutes. Saliva production is quantitated by weighing the sponge before and after chewing. Normal control subjects produced greater than or equal to 2.75 gm of saliva in 2 minutes. Three of 32 consecutive, unselected outpatients in allergy-immunology clinics and 9 of 38 patients in rheumatology clinics had decreased saliva production, which was significantly different compared with controls (P less than 0.01). The presence of sicca symptoms was highly correlated with quantitatively abnormal tear and saliva production, according to the results of the Saxon and Schirmer's tests.

Atom equivalents for relating ab initio energies to enthalpies of formation

Abstract: Sets of atom equivalents have been developed which permit the estimation of heats of formation, ΔH° f298 (g), from ab initio total energies (3‐21G and 6‐31G* basis sets). This extends the isodesmic reaction scheme of Pople and the group equivalents of Wiberg. A variety of small inorganic and organic molecules, including fluorocarbons, free radicals, carbocations, and protonated species give excellent agreement with experiment; average errors are less than 1 kcal/mol with unstrained hydrocarbons (both basis sets), and are on the order of 2 kcal/mol for all molecules considered (6‐31G*; the 3‐21G basis errors, as expected, usually are somewhat higher). The results substantiate Pople's early conclusions that Hartree‐Fock theory provides a generally satisfactory description of classical molecules.

Properties of CsI(TI) — Renaissance of an old scintillation material

Abstract: CsI(TI) is an interesting material for calorimeters in high energy physics. Properties of this material are reported.

Two-bit correlation.

Abstract: We examine simplified correlation through the use of binary data. For the sake of economy we represent the real input u(x) by one amplitude bit per pixel and the correlation filter by one phase bit per Fourier pixel. With such a crude representation of input and reference, it is possible indeed to obtain fairly good correlation results.

Bispectral analysis at low light levels and astronomical speckle masking

Abstract: The bispectrum is the Fourier transform of the triple correlation, sometimes also referred to as the triple-product integral. The influence of photon noise on the bispectrum of an image-intensity distribution is discussed. As an example, the astronomical speckle-masking method is considered. Speckle masking is a method to overcome image degradation that is due to the turbulent atmosphere. It is shown theoretically that bispectral analysis in speckle masking should yield true, diffraction-limited images in all those cases in which the speckle-interferometry process has been successful in reconstructing the object autocorrelation.

Thinking about thinking: Causal, evaluative and finalistic cognitions about social situations

Abstract: The present article is concerned with first considerations and data for a theory of social cognitions. A taxonomy of social cognitions is suggested comprising three classes: causal, evaluative and finalistic thinking. These classes are subdivided according to the social perspective taken, i.e. self-directed versus other-directed thinking. The situational preconditions of these social cognition classes are studied in different social episodes each comprising either positive or negative, expected or unexpected events. The results show that the most reasoning about a situation occurs when it is an important private episode with an unexpected and affectively negatively experienced event. The data concerning the natural occurrence of the three cognition classes is interpreted as providing suggestions of their functional meaning: The functions of the three classes of social cognitions are labelled ‘information integration’ (self-directed evaluative thinking), ‘action planning’ (self-directed finalistic thinking and other-directed causal thinking), ‘control of negative feelings’ (self-directed causal, and finalistic thinking) and ‘understanding’ (other-directed finalistic and evaluative thinking and self-directed causal thinking).

The mixed-alkali effect — a permanent challenge

Abstract: The mixed-alkali effect which is revealed most clearly in the data of electrical conductivity is reviewed by treating existing experimental data in the light of an extended version of the approach by Hendrickson and Bray. The extensions consist basically in taking into account the temperature dependence of the electrical conductivity of the interacting alkali ions and in assuming an inversely proportional temperature dependence for the “S-values” which were introduced by Hendrickson and Bray. These extensions allow a mathematical fit for all data of electrical conductivity as a function of the alkali mole fraction and temperature with a set of four variables. Based on the mathematical treatment a novel interpretation of the mixed-alkali effect is attempted in terms of a pathway model. This model assumes that alkali ions migrate along type-specific pathways, further that ions in their type-specific pathways can be impeded by the proximity of a foreign ion in its own pathway, and that the pathways are established from the molten state in the glass transition range during cooling.

Optical synthesis of the Hartley transform.

Abstract: La transformation de Hartley est reelle et offre un accroissement significatif dans la vitesse de calcul des spectres des images et dans le calcul des operations de filtrage des images. Deux configurations optiques possibles ont ete trouvees pour representer la transformation de Hartley d'un objet

Quantum calculations of rotational and NMR relaxation, depolarized Rayleigh and rotational Raman line shapes for H2(HD)−He mixtures

Abstract: The two ab initio vibrotor potentials of H2−He previously published by Meyer, Hariharan, and Kutzelnigg have been composed in one potential grid. After using this potential in close coupled scattering calculations we have subsequently obtained rotational relaxation cross sections for para- and ortho-H2, NMR relaxation times for ortho-H2, depolarized Rayleigh line broadening cross sections for para-, ortho-, and normal-H2, and rotational Raman line width and shift cross sections for S0(0), S0(2) transitions, at temperatures between 20 and 450 K. The agreement with previous and more recent measurements has been found completely satisfying, with the exception of the rotational relaxation cross sections of para-H2. Throughout the paper previous results derived from the multiple property fit of Shafer and Gordon have been included for comparison. The new ab initio potential is obviously better, except for the rotational relaxation cross sections. The interaction potential of HD−He transformed from the new H2−He potential is also presented in this paper. It has been used recently in a very successful application of the Waldmann-Snider kinetic theory describing transport, relaxation, and reorientation phenomena in magnetic fields. Therefore, only the rotational relaxation cross sections, converged up to about 400 K, have been presented in this paper.

The action of anticlastogens in human lymphocyte cultures and their modification by rat-liver S9 mix. II. Studies with vitamins C and E.

Abstract: The action of vitamins C (VC) and E (VE) on the clatogenic activity of trenimon (TR), cyclophosphamide (CP) and bleomycin (BM) was tested on cultures of human peripheral blood lymphocytes with and without addition of rat-liver S9 mix. In addition, the influence of both anticlastogens on the SCE-inducing activity of TR and CP was examined under the same conditions. A distinct dose-dependent anticlastogenic effect of VC was detected in the action of long-term treatment (24 h) with TR, if the vitamin was added to the cultures simulatneously with or before the clastogen. In the short-term tests (2 or 3 h clastogen treatment ending 23 h or 21 h before harvesting) simultaneous addition of both vitamins did reduce the chromosome-damaging action of TR whether S9 mix was present or absent. While VC also decreased the frequency of chromosome damage induced by S9-mix-activated CP, VE was inactive under the same conditions. Neither vitamin significantly affected the chromosome-breaking activity of BM if S9 mix was absent, but they increased the clastogenicity of BM metabolized by S9 mix. In contrast to their anticlastogenic efficacy neither of the vitamins displayed any significant anti-SCE effect, nor were they active in affecting the inhibition of cell proliferation caused by TR or CP.

Catabolism of Ap3A and Ap4A in human plasma. Purification and characterization of a glycoprotein complex with 5'-nucleotide phosphodiesterase activity.

Abstract: A hydrolase splitting adenosine(5')triphospho(5')adenosine (Ap3A) to AMP and ADP has recently been detected in human plasma [Luthje, J. and Ogilvie, A. (1984) Biochem. Biophys. Res. Commun. 118, 704-709]. The enzyme has been purified to apparent homogeneity, as stained in a native polyacrylamide gel. From gel filtration data a Stokes radius of 5.9 nm was calculated, suggesting a molecular mass of about 230 kDa. The presence of the non-ionic detergent Triton X-100 did not change the molecular mass. The hydrolase dissociated to three major protein components (66 kDa; 45 kDa; 16 kDa) during polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and mercaptoethanol. Binding of the native enzyme to concanavalin-A--Sepharose and specific inhibition of binding by methyl mannoside indicated that the hydrolase is a glycoprotein. Two of the subunits (66 kDa; 45 kDa) could be affinity-labeled with radioiodinated concanavalin A. Active hydrolase could be prepared in buffers without added metal ions. Treatment with EDTA, however, completely abolished the hydrolytic activity. The enzyme could be reactivated by incubation with Ca2+, Co2+ and, at best, with Zn2+, whereas Mg2+ was ineffective. The affinity of the enzyme for Ap3A was high (Km = 1 microM), with normal Michaelis-Menten kinetics. The homolog dinucleotide Ap4A was also substrate (Km = 0.6 microM) yielding AMP and ATP as products after the asymmetric split. Other dinucleotides, such as NAD, and also mononucleotides (ATP,UTP) were degraded to nucleoside monophosphates indicating a broad specificity of the enzyme. The synthetic compound thymidine 5'-monophosphate p-nitrophenyl ester was substrate with low affinity whereas its 3'-homolog was not hydrolyzed. Optimal activity of the hydrolase was found at pH 8.5.

Upper limits of temperature for growth in chlorella chlorophyceae

Abstract: The upper limit of temperature for growth is a species-specific character in the genusChlorella. The limits of 14Chlorella species range from 26–30°C (C. saccharophila) to 38–42°C (C. sorokiniana), withC. fusca var.vacuolata (34°C) andC. kessleri (34–36°C) assuming an intermediate position. Thus, there is no wide gap in the temperature limits between the normal (“low-temperature”) species ofChlorella and the “high-temperature” species,C. sorokiniana.

Applications of the tandem component: an element with optimum light efficiency.

Abstract: The tandem component is a holographic component which permits generation of a general complex wave front with 100% light efficiency. It consists of two phase-only elements in two Fourier conjugate planes and of a lens. Applications of this component are discussed such as complex wave front reconstruction, beam shaping, and correlation type measurements.

Present status of neurosurgery in the treatment of prolactinomas.

Abstract: Our experience with prolactinomas started in 1972 and is based on about 370 patients. Of these 247 were treated surgically, about 110 underwent medical therapy and a small number of patients were observed only. In microprolactinomas prolactinlevels could be normalized in up to 80% of the patients after selective adenomectomy. However, true recurrences were observed in 16% of the patients during long-term follow-up. The operative risk is rather low. There was no mortality in this series. The rate of complications is about 1%. Medical treatment with dopamine-agonists is successful especially in women who desire pregnancy, but should only be used in small microadenomas, in order to avoid complications. In larger macroprolactinomas h extra-sellar extension in whom primary surgical removal leads to a normalization of prolactin-levels in a minority of cases only primary therapy with dopamine-agonists leads to shrinkage of the tumour mass in about two-thirds of the patients. Since the tumour mass does not disappear completely after short-term medical treatment, we favour additional surgical tumour removal instead of long-lasting administration of dopamine-agonistic drugs in higher dosages.