Coherent beam combining of a narrow-linewidth long-pulse Er3+-doped multicore fiber amplifier.

Active phase locking of a multicore erbium-doped fiber amplifier is demonstrated for 180 ns narrow-linewidth pulses at 1545 nm. A spatial light modulator is used at the input of the amplifier to control the optical phase of 7 beams injected in the hexagonally-arranged cores, ensuring efficient combining through a SPGD algorithm. At the output, combining is performed using a diffractive optical element. This experiment establishes multicore amplifiers as a promising way to scale the energy of Brillouin-limited pulsed amplifiers for LIDAR applications. We also present a simple lensless technique to measure phase shifts between pairs of adjacent channels that could be implemented in future active coherent combining systems.

Objective measurement of physiological signal-to-noise gain in the brainstem response to a synthetic vowel.

OBJECTIVE: This work investigates auditory speech processing in normal listeners through measurement of brainstem responses to the synthetic vowel /a/. METHODS: The vowel is presented in quiet and in continuous white noise with different signal-to-noise ratios (SNR) of +5, 0, -5, and -10 dB. RESULTS: In the presence of noise, transient response waves V and A are delayed when compared to those evoked in quiet, whereas the amplitude of wave V and the steepness of the slope between waves V and A are strongly reduced. The spectral component of the steady-state evoked response corresponding to the fundamental frequency (F0) of the vowel shows significantly greater amplitude and local SNR in the less severe noise conditions compared to the quiet condition. Such increases of the amplitude and SNR were not observed for the spectral component corresponding to the first formant of the vowel (F1). CONCLUSIONS: Results suggest that, at F0, both local noise suppression and signal enhancement contribute to the SNR gain. There is suppression of local noise near F1, but no signal enhancement. SIGNIFICANCE: The physiological SNR gain was estimated to be approximately +12 dB at both F0 and F1, as stimulus SNR was reduced from +5 to -10 dB.

Effects of hyperthermic seizures on the developing primary visual cortex of the rat.

Febrile seizures occurring during childhood have been shown to interfere with the development of cognitive functions. However, an alteration of the developing sensory systems might also result from febrile seizures. In order to test this hypothesis, seizures were induced by hyperthermia in Long Evans rats on postnatal day 10. Extracellular single neuron recordings were carried out from postnatal days 15 to 30 and at adulthood. The response of neurons in the primary visual cortex to drifting sinusoidal gratings was recorded in anaesthetized rats. As soon as postnatal day 15, the neurons of rats having experienced a hyperthermic seizure showed significantly lower optimal spatial frequencies (SF), broader directional and temporal bandwidths, as well as higher contrast thresholds than did neurons recorded in normal rats. At adulthood, significantly broader spatial bandwidths and lower optimal temporal frequencies (TF) were obtained from neurons of rats subjected to hyperthermia. These results suggest that febrile seizures during infancy could affect the development of spatio-temporal receptive field properties of neurons in primary visual cortex. Such alterations of a sensory system might contribute to the cognitive deficits associated with early-onset febrile seizures.

Vertical inversion of the visual field and REM sleep mentation.

The effects of the vertical inversion of the visual field on REM sleep mental activity were examined to explore the potential involvement of this activity in information processing. In a first experiment, four male subjects slept in the laboratory for two sessions of 6 consecutive nights: 2 adaptation nights, 2 nights of polysomnography and 2 nights of dream collection. During the days preceding Nights 3, 4, 5, 6 of each session, the subjects wore glasses which, during the second session, completely inverted (rotation of 180 degrees) their visual field. In a second experiment with four other male subjects, the order of conditions was reversed and the experimental condition (visual inversion) was introduced twice. The data of the two experiments were combined. Overall, following visual inversion, there were significant increases in the proportion of dreams containing motor and visual difficulties (P < 0.005), misfortunes (P < 0.05) and dreamer confusion (P < 0.05) and a decrease in dreamer participation (P < 0.05). Only 4 of the 8 subjects experienced incorporations of the inverted visual field into their dreams and they tended to perform better on two of three tests of adaptation to the visual inversion. The observed changes in dreams are consistent with the notion of continuity between waking and dreaming since they appear to reflect the waking preoccupation and psychological state associated with visual inversion.

[Paradoxical sleep and information processing: exploration by inversion of the visual field]. / Le sommeil paradoxal et le traitement de l'information: une exploration par l'inversion du champ visuel.

The purpose of this study was to test the potential relationship between REM sleep and information processing with inversion of the visual field. In the first experiment, four male subjects slept in the laboratory for two sessions of 6 consecutive nights: 2 adaptation nights, 2 nights of polysomnography, and 2 nights of dream collection. During the days preceding Nights 3, 4, 5, and 6 of each session, the subjects wore glasses which, during the second session, completely inverted (rotation of 180 degrees) their visual field. In a second experiment with four other male subjects, the order of conditions was reversed, and the experimental condition (visual inversion) was introduced a second time. When the data of the two experiments were combined, there was a significant (p less than .01) increase in the percentage of REM sleep from Nights 3 and 4 of the control condition to Nights 3 and 4 of the visual inversion condition, but there was no significant change in any of the other sleep stages. There was a significant decrease in horizontal (p less than .04) and vertical (p less than .005) REM density and in the density of vertical REM bursts (p less than .02). The increase in REM sleep supports the hypothesis that REM sleep contributes to information processing while the decrease in REM density suggests that this component of REM sleep may be involved in a homeostatic process of sensory input.

[Nutritional status of patients with digestive system cancer: preoperative prognostic significance]. / Etat nutritionnel des malades atteints d'un cancer digestif: valeur pronostique pré-opératoire.

We have attempted to establish a prognostic nutritional index prospectively in 633 patients with digestive carcinoma making it possible to predict tumor resectability and occurrence of postoperative complications. The following factors were studied prior to surgery: age, sex, weight loss index, triceps skinfold thickness, midarm circumference, lymphocyte count, plasma albumin, transferrin and prealbumin levels, delayed hypersensitivity as investigated by 8 skin tests. The prognostic nutritional index was calculated using Mullen's formula. Unidimensional and multidimensional studies (linear discriminant and logistic discriminant analyses with partial correlations) were used for the statistical analysis. Mortality was 6,7 p. 100 while 16,2 p. 100 of patients presented a postoperative complication. The following variables showed a significant correlation with the resectability of the tumour: weight loss (p less than 0.0001), triceps skinfold thickness (p less than 0.01), midarm circumference (p less than 0.01), total lymphocyte count (p less than 0.01), plasma transferrin (p less than 0.01), delayed hypersensitivity (p less than 0.05). In the occurrence of postoperative complications there was a statistically significant value only to weight loss (p less than 0.001) and delayed hypersensitivity (p less than 0.05). Logistic discriminant analysis gave a linear model predicting tumor resectability in 78 p. 100 of patients and postoperative complications in 86 p. 100 of patients in which weight loss and delayed hypersensitivity were statistically significant. No prognostic value of Mullen's index was found. This study shows that assessment of the preoperative nutritional status of patients with gastrointestinal cancer makes it possible to predict tumor resectability and postoperative complications.

[Total esophagectomy by stripping without thoracotomy in cancer of the pharynx, esophagus and cardia. 34 cases]. / L'oesophagectomie totale par "stripping" sans thoracotomie dans les cancers du pharynx, de l'oesophage et du cardia. Trente-quatre observations.

Total oesophagectomy by stripping without thoracotomy was performed in 34 cancer patients to reduce operative mortality and morbidity in those with impaired respiratory function. The carcinoma was located in the pharynx in 20 cases, on the cardia in 9 cases and on the lower oesophagus in 5 cases. Reconstruction in the posterior mediastinum was effected with the descending colon in 32 patients. The operative mortality rate was 11.8% and fistulization developed in 20.6% of the cases. Eight patients (26.5%) required post-operative endoscopic dilatation. Ninety per 100 of the patients who survived surgery resumed satisfactory feeding. Thus, these patients with high operative risk who underwent oesophagectomy by stripping without thoracotomy benefited from tumoral excision and normal feeding with results comparable to those of other types of oesophagectomy.

[Efficacy of hyperselective vagotomy on duodenal ulcer. 284 cases]. / Efficacité de la vagotomie hypersélective sur la maladie ulcéreuse duodénale. 284 observations.

Two hundred and eighty-four patients who underwent highly selective vagotomy for duodenal or prepyloric ulcer were followed up for at least 1 year, and 47.9% of them for at least 5 years (mean : 58 months). The actuarial recurrence rates were 4.7% at 3 years, 9.6% at 5 years and 13.1% at 7 years. These results do not agree with the recently published figure of 20%. The authors insist on the necessity to dissect the lower oesophagus on a length of at least 5 cm. In duodenal ulcers, this technical detail should result in a cure rate of about 90% at 5 years.

[Horizontal laparotomy in biliary tract surgery]. / La laparotomie horizontale en chirurgie biliaire.

For operations on the biliary tract the transverse horizontal incision has the same advantages as the subcostal approach: strong abdominal wall, little influence on ventilation and wide access to the subhepatic region. But in addition, the abdominal wall nerves are preserved as much as possible, post-operative evisceration, it is occurs, can easily be repaired and subsequent surgery can be performed using the same route.

[Effects of cholecystectomy on functional signs associated with cholelithiasis]. / Effets de la cholécystectomie sur les signes fonctionnels associés à la lithiase vésiculaire.

Two hundred hospital patients with gallstones who had been cholecystectomized on account of typical biliary colics were investigated for migraine, headache, malaise, vertigo, flatulence, diarrhoea or constipation 2, 6, 12 and 24 months after the operation. The study showed that these symptoms are common in patients with biliary lithiasis, particularly women, and that their frequency increases with the duration of the disease. The beneficial effects of cholecystectomy are uncertain and appear to decrease with time ; only 30% of the patients seemed to improve after surgery. It is concluded that these symptoms betray real functional disorders, that cholecystectomy is not the appropriate treatment for them and that any improvement observed may be credited to the placebo effects of the operation.

Choledochoscopy in common bile duct surgery for choledocholithiasis: A must: Eight years experience in 441 consecutive patients.

Between 1975 and 1983, 441 choledochoscopy were performed in a series of 451 consecutive patients undergoing surgical common biliary duct exploration for choledocholithiasis. In 127 patients (27.8%), no stones were found. Forty-five cases (10%) of choledocholithiasis missed by surgical and radiologic exploration methods were found by choledochoscopy. Therefore the retained stone rate decreased from 10 per cent to 2 per cent. Fourteen patients (3%) died at surgery, ten of whom (2%) were over 70. Postoperative biliary tract was drained in 98 patients (8%) using external drainage. Biliary tract patency was checked on the tenth postoperative day by the tube cholangiography. When retained stones were not found, T-tube was removed on the 20th day after surgery. When retained stones were found (11 patients, 2%) an endoscopic papillotomy was performed. Choledochoscopy is a significant addition in biliary surgery. It reduces operative mortality and morbidity, decreases retained stone rate, diminishes indications for biliary anastomosis and sphincterotomy, and is easy to perform without specific training. Its extensive and systematic use is advocated when- ever common bile duct patency has to be surgically demonstrated in choledocholithiasis.

Sleep, dreaming, and adaptation to a stressful intellectual activity.

Sixteen male subjects slept in the laboratory for 4 consecutive nights. Night 1 was an adaptation night and night 2 was a baseline night of uninterrupted sleep. On nights 3 and 4 subjects were asked to complete "intelligence" tests prior to sleep. One half of the subjects attempted to complete difficult versions of "intelligence" tests without knowing that they could not be completed in te time allotted. The other subjects were given easier versions of the same tests that they were able to complete in the time allotted. Night 3 was a night of uninterrupted sleep and night 4 involved REM period awakenings for the purpose of dream collection. Stressful manipulation consisted of telling the subjects before the administration of either set of tests that an average university student should complete most of the items within the allotted time. On night 3 both groups showed a significant increase in sleep latency and a significant decrease in REM density compared to the baseline night. On night 4 subjects in the difficult condition experienced significantly more anxiety in their dreams and somewhat higher levels of incorporation of the presleep material than subjects in the easy condition. Our findings suggest that following a stressful experience uninterrupted sleep has more short term adaptive value than a procedure which enhances dream recall and that subjects who incorporate elements from a presleep stressful event into their remembered dreams show less adaptation on awakening than subjects who do not.

Comparison of polyacrylamide and agarose gel thin-layer isoelectric focusing for the characterization of beta-lactamases.

Plasmid-mediated beta-lactamases from strains of Escherichia coli and Pseudomonas aeruginosa were separated by isoelectric focusing on a 0.8-mm thin-layer agarose gel with a pH gradient of 3.5 to 9.5. Their banding patterns and isoelectric points were compared with those obtained with a 2.0-mm polyacrylamide gel as the support medium. The agarose method produced banding patterns and isoelectric points which corresponded to the polyacrylamide gel data for most samples. Differences were observed for HMS-1 and PSE-1 beta-lactamases. The HMS-1 sample produced two highly resolvable enzyme bands in agarose gels rather than the single faint enzyme band observed on polyacrylamide gels. The PSE-1 sample showed an isoelectric point shift of 0.2 pH unit between polyacrylamide and agarose gel (pI 5.7 and 5.5, respectively). The short focusing time, lack of toxic hazard, and ease of formulation make agarose a practical medium for the characterization of beta-lactamases.