Two-Color Radiation Generated in a Seeded Free-Electron Laser with Two Electron Beams.

We present the experimental evidence of the generation of coherent and statistically stable two-color free-electron laser radiation obtained by seeding an electron beam double peaked in energy with a laser pulse single spiked in frequency. The radiation presents two neat spectral lines, with time delay, frequency separation, and relative intensity that can be accurately controlled. The analysis of the emitted radiation shows a temporal coherence and a shot-to-shot regularity in frequency significantly enhanced with respect to the self-amplified spontaneous emission.

Observation of time-domain modulation of free-electron-laser pulses by multipeaked electron-energy spectrum.

We present the experimental demonstration of a new scheme for the generation of ultrashort pulse trains based on free-electron-laser (FEL) emission from a multipeaked electron energy distribution. Two electron beamlets with energy difference larger than the FEL parameter ρ have been generated by illuminating the cathode with two ps-spaced laser pulses, followed by a rotation of the longitudinal phase space by velocity bunching in the linac. The resulting self-amplified spontaneous emission FEL radiation, measured through frequency-resolved optical gating diagnostics, reveals a double-peaked spectrum and a temporally modulated pulse structure.

High-order-harmonic generation and superradiance in a seeded free-electron laser.

Higher order harmonic generation in a free-electron laser amplifier operating in the superradiant regime [R. H. Dicke, Phys. Rev. 93, 99 (1954).] has been observed. Superradiance has been induced by seeding a single-pass amplifier with the second harmonic of a Ti:sapphire laser, generated in a ß-Barium borate crystal, at seed intensities comparable to the free-electron laser saturation intensity. Pulse energy and spectral distributions of the harmonics up to the 11th order have been measured and compared with simulations.

[Efficacy of a low-residue diet in the prevention of immuno-nutritional changes caused by the preparation of the colon for surgery]. / Efficacia di una dieta a basso residuo nella prevenzione delle alterazioni immunonutrizionali indotte dalla preparazione del colon.

Twenty-four patients about to undergo colorectal resection for cancer were randomly divided into two groups of 12: A and B. All had an uninterrupted colonic preparation for colonoscopy and surgery involving dietary restrictions for 4-8 days (450 calories; 25 g. proteins daily). In the group B an additional intake of 1200 Kcal. and 32 g. protein daily was given by a low-residue diet. Body weight, lymphocytes, albumin, prealbumin, C3, C4 and Complement activity (CH100) were evaluated on admission and after bowel preparation. In group A statistically significant decrease were found in all the parameters. In group B significant reduction occurred only in C4. The data confirm a relationship between immuno-nutritional state and preparation for colonic surgery, and suggest that a preoperative nutritional support may avoid or limit bio-humoral changes, indicative of an immuno-nutritional impairment.

[Research on correlations between immuno-nutritional parameters and oncologic stage in patients operated on for cancer of the stomach]. / Ricerca di correlazione tra parametri immunonutrizionali e stadio oncologico in soggetti operati per cancro dello stomaco.

A correlation was sought, in 40 patients operated on for gastric cancer, between a number of immunological and nutritional variables and oncological stage. Prealbumin, transferrin, C3, C4, total complement (CH100), total serum lymphocytes, IgG, IgA and IgM were evaluated preoperatively prior to commencing any nutritional treatment. Statistical analysis was performed with a view to assessing whether the values of the above-mentioned parameters, taken singly or as a whole, differed in the 4 in the 4 oncological stages (UICC 1978). Analysis of individual parameter values showed a significant difference between stage I and stage IV with regard to prealbumin and between stages I and II with regard to C3 (p = 0.0165 and p = 0.0329, respectively). When evaluating the 9 parameters as a whole, no significant differences emerged, though such differences might be detected on increasing the study population and by adopting statistical procedures aimed at eliminating the least significant variables from the model.

Effect of ibopamine on peripheral haemodynamics.

Peripheral haemodynamics was studied in healthy volunteers by strain gauge plethysmography after administration of ibopamine (IB), diisobutyric ester of N-methyl-dopamine, an orally active dopaminergic agonist. Seven subjects received a single oral dose of ibopamine of 150 mg and 6 received a daily dose of 150 mg (50 mg t.i.d.) for 5 consecutive days. Arterial resting blood flow and venous capacity increased and peripheral resistance decreased significantly. Six further subjects were then studied; 3 h after an oral dose of ibopamine 150 mg, the parenteral administration of Sulpiride 50 mg, a specific vascular dopaminergic antagonist, was found significantly to counteract its peripheral activity. Heart rate and arterial blood pressure were never affected and tolerability was good.

Clinical and audiological findings in a case of auditory agnosia.

A case is reported of severe agnosia for verbal and non-verbal sounds without associated aphasic disorder. A CT scan revealed bilateral, temporal lobe lesions from two ischaemic accidents that had occurred 9 months apart. The search for subtle deficits in the patient showed normal sensitivity to changes in the intensity and frequency of simple sounds; in contrast, his ability to discriminate sound duration and musical note sequences was severely impaired. The simultaneous recording of the whole auditory-evoked response pattern revealed no abnormality in the early components, which reflect the activation of the auditory nuclei and pathways of the brain stem. However, the middle and late components were delayed and slowed. These results and others in the literature suggest that the neocortex in man, as in other mammals, plays an essential role in the temporal aspects of hearing. Also, the two main ingredients commonly recognized in auditory agnosia, i.e. word deafness and the inability to interpret non-verbal sounds, are caused by the disruption of elementary, bilaterally represented cortical functions which start the processing of every kind of auditory information.