Search

Resonance and direct line fluorescence occurring in flames at atmospheric pressure are critically discussed. A knowledge of the different ways of populating and depopulating the fluorescent level is needed in order to define more correctly the excitation processes. Thermally assisted resonance fluorescence and thermally assisted antistokes fluorescence, previously demonstrated in the case of indium, were experimentally observed also for gallium. Moreover, an increase in concentration of analyte permits observation of the same processes also for thallium, by using a hotter flame. A general equation is presented, which points out the role of the thermal energy. Finally, atomic fluorescence of chromium is also discussed on the basis of the possible complicated population mechanisms.

A direct-reading optical spectral method for uranium isotope analysis is described. A slow scanning exit slit-photomultiplier assembly has been designed and mounted on the Jarrell-Ash 3.4 m Mark IV spectrometer, the line intensities being recorded through a phase sensitive a.c. amplifier system. The pelletting of U3O8 with Cu powder results in a fast and reliable preparation method for the deposition of the sample into the cathodes of the hollow cathode lamp, thus allowing stable and intense light output to be reached within few minutes after the discharge has been struck. Uranium-235 concentrations from 0.5 to 93% can be determined with a precision, at 99% confidence level, ranging from 1.97 to 0.28%.

Teulié Henri, Rossi G. L'anthologie provençale de maître Ferrari de Ferrare. In: Annales du Midi : revue archéologique, historique et philologique de la France méridionale, Tome 13, N°49, 1901. pp. 60-73.

Cardiac output and blood flow to the kidney, hind limb, and splanchnic area were studied in anesthetized dogs during the arterial pressure rise due to carotid occlusion. All the vascular beds studied exhibited an increased resistance to flow. Cardiac output was maintained constant through an increased cardiac work in spite of the increased arterial pressure. This increased cardiac work was reflexly produced as evidenced by the action of the adrenergic blocking agent dichloroisoproterenol (DCI). This drug allowed the reflex vasoconstriction and the consequent pressure rise, but preventing the reflex chronotropic and inotropic sympathetic effects on the heart resulted in a fall of cardiac output during carotid occlusion. It is concluded a) that the reflex increase in vasomotor tone is the main factor in the pressor response to carotid occlusion and b) that the reflex effect on the myocardium is an important factor in regulating cardiac output in this situation.

The iodoproteins from goitrous rat thyroid glands (300–800 mg), obtained by prolonged (20 months) and severe iodine deficiency, were isolated and characterized. The animals were given a low iodine diet (2 μg 1/100 g diet) containing 125I for 81 days (approach to equilibrium) and then they were pulse—labeled with 131I and 3H—leucine 2 hr prior to sacrifice. Thyroglobulinlike iodoproteins represented only 5% of the total protein in the crude soluble extract with 19 S comprising 90% and 27 S 10%. There was almost no iodine in 19 S while 27 S contained 0.12% iodine. Therefore a large proportion of the iodine stored in the soluble iodoproteins was due to the iodine in the 27 S protein. The turnover of iodine in 27 S, however, was much slower than in 19 S. In these severely iodine deficient animals the distribution of soluble thyroid iodoproteins was not significantly different from that observed in normal glands; the low iodine content, however, affects the stability of thyroglobulin. The iodinefree 19 S was m...

The causal Meyer‐Suura structure functions are projected into irreducible representations of the Lorentz group. A clarification of the connection between light‐cone singularities and Lorentz poles is obtained: We find that in general a light‐cone singularity of the type 1/(− x2 + iex0)α, in the operator product of the hadronic electromagnetic current, is built up from a sequence of Lorentz poles at λn = 1 + α − n whose residues are polynomials of order n in the virtual photon square mass.

The possibility of using other U lines than the 4244 A line for an optical spectral determination of 235 U 238 U isotope ratios has been investigated. The isotopic pattern of the lines at 4116.097, 4689.074 and 4859.750 A was studied. The structure at 4116 A has been found to be the most attractive owing to the very low hyperfine structure effect on the 235U component. Absolute isotope ratio measurements were obtained for 235U concentrations between 10 and 93 per cent, the relative sample-to-sample variance being 0.5 per cent at the lowest concentration level. Below 10 per cent of 235U a moderately intense line interferes at the position of the 235U line, thus limiting at present the applicability of the described method. The possible nature of the interference line is discussed. Some preliminary results on the absolute determination of 236 U 238 U isotope ratios, obtained on the structure at 4244 A, are also presented.

Prolonged acoustic trauma associated with neomycin sulphate treatment brought about the complete destruction of the organ and ganglion of Corti in a series of guinea-pigs. Koelle and Friedenwald's test revealed the persistence of AChE activity in the intraganglionic spiral bundle but not on the basilar membrane, where Cajal-De Castro's silver impregnation method failed to disclose the presence of nerve fibres. Emphasis is laid on the different response displayed by the efferent and afferent fibres to the degenerative processes caused by the described treatment.

En resumant les donnees de la litterature et les resultats de ses recherches morphologiques et fonctionnelles, l'Auteur expose nos actuelles connais-sances a propos de l'innervation efferente des recepteurs vestibulaires.Conference prononcee le 10 mai 1963 a la « Societa di Scienze Mediche e Naturali dell'Uni-verslta di Sassari ».

The electroproduction structure functions, defined on a suitable homogeneous space with respect to the spinor groupSL2,C, are subjected to harmonic analysis. In this way the Bjorken limit and the scaling law can be recovered by simple assumptions and a sum rule is obtained. The connection of this analysis with a generalized light-cone expansion is derived.

The electronic excitation temperature of several flames of analytical use has been calculated from atomic fluorescence measurements on thallium using a continuum or a broad line source as the excitation source. A calibration of the relative efficiency of the optical detector system was necessary as well as an accurate knowledge of the irradiance ratio of the exciting source at the wavelengths considered. A way to derive this last factor empirically is also shown. Four theoretical possibilities of flame temperature calculation are considered and discussed, the practical results obtained by three of these possibilities being compared to those of the “line-reversal” and the “two-lines” methods. The excellent agreement of the values demonstrates that atomic fluorescence spectrometry can be considered at least as valuable as the other well established and widely used spectroscopic methods of flame temperature evaluation.

A study about the cell wall of AVENA coleoptile epidermis cells. — A new type of lamellae structures embedded in the outer periclinal wall of oat coleoptile epidermis cells has been observed. These structures are present more frequently in the inner non-cutinized portion of the cell wall; their orientation, most often parallel to the cell surface, follows a regular pattern. They are formed by alternate layers of electrontransparent and electron-dense bands. The thickness of these lamellar bodies is about 200–300 A; their length is rather difficult to determinate. They are bounded by a 30–40 A thick membrane; the inner compartment is formed by a central highly manganophilic zone 50–70 A thick where several thin lamellae can be seen and by two lateral zones about 40–50 A in thickness. Embedded in the cutinized portion of the wall some elliptical bodies have also been observed, surroundedd by a single membrane, 20 A in thickness. The interior of these bodies shows thin lamellae enclosed in an electr...

A simplified model to evaluate the neutron spectrum in cluster fuel elements, which was previously concerned with ‘thermal’ effects, has been extended to take into account the epithermal ones. This has been done on the basis of a simple separation of the ‘homogeneous’ spectrum effects, which have been evaluated by means of a preliminary homogenization of the cell. On the basic homogeneous spectrum obtained in this way the heterogeneity effects characteristic of the fuel element (rethermalization and geometrical hardening)-separately evaluated- have been applied. The difficulties connected with the introduction in this simple framework of the interference effects between hardening and rethermalization are discussed and a comparison with the reaction-rate ratios measured at Chalk River is presented.

The possibility of exciting the fluorescence of several elements with the “overlapping” lines of other elements and the effectiveness of exciting the fluorescence of Fe, Mn, Ni, Cr, Tl, Cu and Mg with a 90 W mercury discharge lamp, are discussed. A method of increasing the fluorescence radiation by suitable optics, with a simple adaptation of a Jarrell-Ash AA spectrometer, is described. A two-pass system of the incident radiation into the flame is coupled with a mirror, in the optical axis, which reflects the fluorescence radiation emitted at the opposite side to the monochromator slit. This produces an increase of 168% of the signal. Detection limits for 10 elements are reported.

A new optical setup for increasing the intensity of atomic fluorescence flame spectrometry is presented. The arrangement consists of two concave spherical mirrors and an elliposidal mirror whose primary focus is located at the flame position, and secondary at the entrance slit of the monochromator. Approximately 10 times gain in the measured intensities was obtained. The system is also useful for flame emission work, for which about five times gain was observed. With a low background flame such as the air–H2 for the N2−H2 diffusion flame and 400 µ slits, calcium can be detected at the level of 0.005 µg/ml. Moreover, the observed thermally assisted anti-Stokes fluorescence of In and Ga can be of analytical importance since the detection limits with a total consumption burner and the air-H2 flame were found to be 0.015 and 0.02 µg/ml, respectively. Detection limits in atomic fluorescence for Cr, Tl, In, and Fe are also presented.

In two groups of experiments in guinea-pigs (cerebellectomy; monolateral cut of the cerebellar peduncles), the Nauta-Gygax stain as modified by Rasmussen and McCrane showed the existence of fibres connecting the cerebellum to the cochlear nuclei, the retro-olivary nucleus and the pre-olivary nuclei.

n/a

A sensitive method has been established for the determination of traces of Be, La, Eu, Gd, Dy, Sm and Er in purified uranium compounds. The elements were first separated from uranium by means of a column of TNOA supported by SiO2, followed by a spectrographic determination. By using a modified copper spark technique detection limits between 7·10−4 μg Be and 1·10−2 μg Sm were achieved.

n/a

Introduction The parotid gland is the most important organ in the glandular system connected with the upper air-digestive tracts. This system is composed of the greater salivary glands (parotid gland, submaxillary gland, sublingual gland) and of the lesser salivary glands (glands annexed to the trachea, to the bronchi, etc.). Some interesting anatomoclinical and surgical problems are connected with the parotid gland. They derive from the relationship of this gland with the facial nerve. Each neoplastic operation must make possible the removal of the tumor and must obviate recurrences, which often cause difficult surgical problems. Parotid surgery in the majority of cases, is concerned with excision of the so-called "mixed tumors," which have a far higher recurrence rate than other tumors of this gland. In these cases preservation of the anatomic and functional integrity of the facial nerve must not be attained by performing an operation that is not radical. In

The construction and set-up of a dual-flame photometric detector (DFPD) which, through “three channel” operation, allows the simulatneous selective determination of P-, S-, Cl-containing compounds eluted from a G. C. column is described. For P- and S-containing compounds the molecular emission bands HPO and S2 at 526 and 394 nm respectively are measured; for Cl-containing compounds, after reaction with In, the InCl band at 360 nm is recorded. Detectability, specificity, linearity as well as mutual interferences are discussed and compared with those of classical GC-detectors as thermionic (TID) and electron capture (ECD). Some practical applications concerning the pesticide residue analysis in animal and vegetable extracts are shown.

Koelle and Friedenwald's test for acetylcholinesterase has been used in a study on the following laryngeal muscles in man: vocalis, cricothyroid, lateral crico-arytenoid and posterior crico-arytenoid. Serial sections were made with the freezing microtome and a number of muscles were submitted to microdissection. “Multi-motor end-plate” fibres were found in all four muscles studied (70 to 80 per cent in the vocalis muscle, about 50 per cent in the cricothyroid and lateral crico-arytenoid muscles and about 5 per cent in the posterior crico-arytenoid muscle). None of the fibres of the vocalis muscle was found to be inserted into the vocal ligament. Only in the vocalis muscle was it possible to demonstrate typical muscle spindles, whereas in all four muscles studied “spiral nerve endings” were observed.

Resection of the direct efferent cochlear bundle in the guinea pig causes greater reduction in the cochlear microphonic potential than is caused by resection of the crossed efferent cochlear bundle. The findings of the present series of studies are thought to constitute physiological proof of the existence, in the guinea pig, of another component of direct efferent cochlear fibers, other than the direct olivo‐cochlear fibers, which arises in cells of the reticular formation of the medulla.

A spectrographic method is described for determining hafnium in zirconium. With a single exposure it is possible to cover the concentration range of 100 · Hf Zr from 0.1 to 100. The oxides mixed with a buffer, are excited by a d.c. 20-A arc and the spectrum recorded with a large quartz prism spectrograph. The hafnium concentration is determined from the intensity ratio of the line pairs Hf II 2641.4 Zr II 2856.06 and Hf I 2779.36 Zr I 2792.04 with coefficients of variation = 2.6 per cent and 1.97 per cent, respectively.

Nel presente lavoro si studia la distribuzione delle energie di 506 tracce di elettroni di decadimento di mesoni μ, ottenuta da misure di « scattering ». Le misure sono state eseguite con il metodo delle coordinate e con il metodo angolare; per il calcolo delle energie si e fatto uso della « costante di scattering » di Goldschmidt-Clermont, tenendo conto della variazione di questa con la velocita e con la lunghezza delle celle. Le varianze degli angoli medi di scattering sono state dedotte dalle teorie di Moliere e di d’Espagnat. Lo spettro sperimentale, disperso dalla bremsstrahlung e dalle misure di scattering, viene confrontato con gli spettri teorici (forniti dalle teorie di Michel e di Porter e Primakoff) modificati per tener conto dei due effetti. Il metodo statistico della « massima verosimiglianza » conduce alla stima del parametro di forma ϱ introdotto da Michel, relativo nella presente esperienza ad una mescolanza di particelle positive e negative (ϱ±). Si ottiene ϱ± = 0.57 ± 0.14, dove l’errore e in parte dovuto alle fluttuazioni di frequenza dello spettro sperimentale, in parte all’incertezza sulla costante di scattering. Il valore trovato risulta in buon accordo con quello ottenuto da altri sperimentatori con altre tecniche.

The structure type of joaquinite has been derived from precession photographs (Mo radiation) of a polysynthetic twin. Space group: C 2/m; lattice constants:a=10.50A,b=9.58A;c=11.78A;β=109°32′;cell content: Ba4Fe2RE4Ti4O4[Si4O12]4. The atomic arrangement was determined by Patterson-, Fourier-, and (F0−Fc)-syntheses. The least squares refinement (with isotropic temperature factors) led toR=0.16. The authors are of the opinion that this relativeley highR-value is due to the poor quality of the crystal. The main structural feature are double layers of [Si4O12]-rings parallel to (001) which are connected by 10-coordinated Ba and octahedrally coordinated Ti. These double layers have pseudo-symmetry C mmm, with mirror planes perpendicular toa, b, andc *. They are stacked alongc * and translated −3/8a. The orthorhombic pseudo-symmetry allows also the translation +3/8a which is responsible for both the formation of twins and the frequent stacking disorder. The described double layers are connected by 7-coordinated RE and 4-coordinated Fe. The roles of Fe, which has an occupancy of only 1/2, and of Na and OH. which are reported in published analyses, are discussed.

The numerous works of these last years about the surgical therapy of chronic frontal sinusitis show the importance and the present interest of this subject. The use of antibiotics has certainly reduced the number of cases of chronic frontal sinusitis requiring surgical therapy. But still today, in many cases, the surgical operation is the only way to heal this affection. Therefore the study of the esthetic and clinical problems connected with a surgical therapy of chronic frontal sinusitis is a subject of great interest. It is easy to value the esthetic angle of the problem. The clinical problems, on the contrary, are intimately connected with the embryogenetic development of the frontal sinus. It derives from anatomical formations opening into the middle meatus. The uncinate passage between the frontal sinus and the nasal fossae passes through these anatomical formations. The ethmoidal labyrinth that constitutes the point of anatomic association of the

A malignant tumour of the thyroid gland is reported. The possibility of a simultaneous cancerization of thyroid gland and aberrant thyroids is considered.

n/a

On a etudie sur le lapin les effets dus a l'action directe de l'acetylcholine, du diisopropylfluorophosphate, du tetraethylammonium et de l'atropine sur la fonction des recepteurs vestibulaires.Sur la base des resultats ainsi obtenus, on peut arriver a deduire que l'acetylcholine prend part tant au processus de transmission des stimuli nerveux du recepteur ampullaire A la fibre efferente qu'au mecanisme qui regle la transmission quantitative de ces stimuli.

n/a

In designing and analyzing Type 1, second-order feedback control systems, a linear mode technique is the usual method of approach. Any adverse effects on system performance due to non-linearities are often explained away as the limiting condition in which the system can operate with any degree of predictability. It is the purpose of this paper to present a neomodern control theory with emphasis on a highly predictable technique for nonlinear analysis and design. Practical applications of this technique to the analysis of servo loops in the Central Air Data Computers of the F-111, C-141, and other aircraft present conclusive evidence of its usefulness and its importance to the state-of-the-art of nonlinear systems.

To aid the elaboration of hydro-meteorological data by means of computers and at the same time to reduce to a minimum the work of the operator in obtaining such data, eliminating the perusal of diagrams and data extraction from them, a cartridge magnetic tape recorder has been built with a long recording run, low current consumption to permit battery operation, and above all with cost kept to a minimum to allow its installation as normal in the stations of a hydro-meteorological data gathering network. An appropriate reader-translator enables all the necessary information to be obtained from the data recorded on the magnetic tape cartridge and to generate from this a magnetic tape with an IBM-compatible format organized data. This system will be here described, and reference will also be made to the tests carried out.

Measurements of the decay constant of a neutron pulse as a function of time have been performed in beryllium blocks (15 × 15 × 20 cm 3 and 10 × 15 × 20 cm 3 ) at 20°C, at 153°K and at 90°K. At low temperature, in particular at 90°K, it was possible to follow the pulse evolution until 2·5 msec and the resulting λ ( t ) curve presents some well defined characteristics, which are suitable for a detailed theoretical discussion. In the framework of a phenomenological model it has been shown that for a beryllium block of under-critical dimensions at low temperature a correct comparison between theory and experiments must take into account the spatial dependence of the problem.