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OBJECTIVES: A concealed penis is defined as a phallus of normal size buried in prepubic tissue (buried penis), enclosed in scrotal tissue (webbed penis), or trapped by scar tissue after penile surgery (trapped penis). We report our results using a standardized surgical approach that was highly effective in both functional and cosmetic terms. METHODS: From January 2002 to December 2005, 56 patients (median age 7 years) underwent surgery for a buried penis, 11 (median age 5 years) for a webbed penis, and 20 (median age 8 years) for a trapped penis. All 20 patients with a trapped penis had previously undergone circumcision for phimosis, except for 3 (1 for multioperated lymphangioma, 1 for repaired hypospadias, and 1 for corrected glanular epispadia). All webbed penises were phimotic, requiring circumcision. The surgical technique consisted of complete exteriorization of the shaft and reconstruction of the penopubic and penoscrotal angles. These maneuvers, however, proved extremely straightforward, with the addition of an incision along the scrotal raphe without any incision of the penile skin. RESULTS: All the patients were observed for at least 1 year after repair. Recurrence was observed in 3 boys with a buried penis (5.3%); all 3 boys were obese. Two cases of a trapped penis (10.0%) recurred, but no case of a webbed penis recurred. Regarding complications, 2 patients with a buried penis presented with mild lymphatic stasis of distal shaft that spontaneously subsided within a few months. CONCLUSIONS: The scrotal approach we have described has simplified the complete exteriorization of the penile shaft, with easy bleeding control, avoiding the use of flaps, grafts, and additional ventral Z-plasty often described in published reports. In addition, the cosmetic results were judged to be good by the parents.

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Roux-en-Y jejunostomy (RYJ) permits enteral feeding in children unable to tolerate oral or intragastric feeds. It avoids many of the complications of nasojejunal and gastrojejunal tubes. Here we report our experience of intubated RYJ. By retrospective review of patient notes from 1998 - 2003, thirty-five children were identified. The median age was seven months (1 month - 16 years) and median follow-up was twenty-five months (1 - 55 months). There were no early postoperative complications or deaths. There were eighteen (51 %) late complications: peristomal leak (6), peristomal infection (2), bilious vomiting (5), tube displacement (3), abscess (1) and jejuno-colic fistula (1). Five children progressed to full oral feeds and had the RYJ resected. Fourteen of the twenty-eight children still alive remain fed by RYJ. Nine infants subsequently underwent fundoplication and gastrostomy with RYJ resection. Seven children died during the study period. RYJ is a straightforward procedure which can be performed safely in the face of poor nutrition and significant comorbidity. We recommend RYJ as a medium-term measure for enteral feeding.

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The authors report the case of a baby girl with an unusual communicating bronchopulmonary foregut malformation consisting of extralobar pulmonary sequestration and cystic adenomatoid malformation. A well-formed bronchus was the communication between the sequestration and lower esophagus.

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Laparoscopy has been considered by some Workers an useful means of diagnosing patent processus vaginalis in children. This technique is effective in evaluating patency of contralateral internal inguinal ring and requires only five minutes of additional operative time to elective inguinal herniorrhaphy. The Authors report their experience with fifty-six children to whom this procedure was offered. Their age ranged from three to ten years--mean 6.5 years-. Congenital unilateral hernia was right-sided in eighteen and left-sided in thirty-eight patients. Overall, the contralateral processus vaginalis was patent in 44.6%, with 27.7% and 52.2% patency on the nonclinical right and left sides, respectively. Low abdominal pressure-insufflation with CO2 to a pressure of 4 mmHg and shortened operative time have permitted to avoid endotracheal intubation. We confirm great utility of laparoscopic examination in determining the need for contralateral inguinal exploration in pediatric patients.

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The chaotic behavior of systems with strange attractors can be discussed by examining the flip-flop process associated to the system dynamics. This was already shown by Lorenz (1963) in his first seminal paper. A somewhat surprising result was obtained by Aizawa (1982), who, studying the same Lorenz attractor at the parameter value r = 28, reached the conclusion that the associated flip-flop was a typical Markov process. Since the process is generated in a deterministic way, one may wonder if the Aizawa result is accidental, depending on the particular parameter value, or if a similar conclusion can be extended to other systems, with different attractors. Our conclusions are that the Aizawa result is mostly accidental, because for other parameter values and for other attractors there are sharp deviations from the Markovian process.

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In this work, the results of two experiments on ambiguous patterns are reported, which have been obtained by presenting a series of stimuli designed, in both cases, to reduce gradually the ambiguity of the patterns. Such reduction has been performed by respectively increasing or decreasing the amount of graphic details in the experiments. Data of both experiments show a lengthening of mean reversal time. The increase in the stability of one percept can be regarded as associated with the increasing difficulties encountered by an observer in organizing and restating the alternative "hypothesis" through the perceptual mechanisms. The loss of balance in the durations of percepts is discussed in terms of their different informational contents. Finally, in Exp. 1 an analysis is made to evaluate to what extent an addition of perceptual cues, designed to reinforce a three-dimensional interpretation of a pattern, can influence its figure-ground alternation.

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Reversal rates of an ambiguous figure (the Necker cube) were studied for different pattern sizes covering a range of visual angles theta from approximately 1 to 62 deg. A large number of reversals was obtained for each observer and each pattern in order to examine the statistical distributions of reversal times. A pronounced flattening of the statistical distributions (represented throughout by a gamma distribution) and a growth of the mean duration of each percept, with increasing pattern size was found. A plateau in the range of theta between 5 and 20-30 deg was observed. For larger values of theta two kinds of observers have been identified: for 'fast' observers the inversion rate is little affected by theta, whilst for 'slow' observers, the mean reversal time increases strongly with theta. A tentative model, based on three different contributions to the duration of the alternation process, is proposed: a constant term, independent of theta, and two terms dependent on theta--a retinal term, and a cortical one. The last term is interpreted as due to the spreading of excitation with the characteristic of a filling-in process.

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Double-barreled O2 microelectrodes were used to study O2 diffusion and consumption in the superfused drone (Apis mellifera) retina in darkness at 22 degrees C. Po2 was measured at different sites in the bath and retinas. It was found that diffusion was essentially in one dimension and that the rate of O2 consumption (Q) was practically constant (on the macroscale) down to Po2 s less than 20 mm Hg, a situation that greatly simplified the analysis. The value obtained for Q was 18 +/- 0.7 (SEM) microliter O2/cm3 tissue . min (n = 10), and Krogh's permeation coefficient (alpha D) was 3.24 +/- 0.18 (SEM) X 10(-5) ml O1/min . atm . cm (n = 10). Calculations indicate that only a small fraction of this Q in darkness is necessary for the energy requirements of the sodium pump. the diffusion coefficient (D) in the retina was measured by abruptly cutting off diffusion from the bath and analyzing the time-course of the fall in Po2 at the surface of the tissue. The mean value of D was 1.03 +/- 0.08 (SEM) X 10(-5) cm2/s (n = 10). From alpha D and D, the solubility coefficient alpha was calculated to be 54 +/- 4.0 (SEM) microliter O2 STP/cm3 . atm (n = 10), approximately 1.8 times that for water.

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The immune capacity of chickens made tolerant to human serum albumin just after hatching was studied after a primary and secondary challenge at 7--14 weeks of age, of either 1 mg/kg or 100 mg/kg. The class and avidity of antibody produced by birds "escaping" from tolerance was similar to normal controls. The escaping chickens made a normal peak antibody response to a high dose but not to a low dose (except that the response to a low secondary dose after priming with a high dose was normal); but the decline of the antibody titer was abrupt, indicating inability to maintain the response. It is concluded that the antibody-forming capacity of B cells is normal, but regulation of antibody formation is impaired in previously tolerant chickens.

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1. A system proposed in a previous article as a model of responses of visual cells has been analysed with the purpose of predicting the features of responses to single absorbed photons.2. As a result of this analysis, the stochastic variability of responses has been expressed as a function of the amplification of the system.3. The theoretical predictions have been compared to the results obtained by recording electrical responses of visual cells of Limulus to flashes delivering only few photons.4. Experimental responses to single photons have been tentatively identified and it was shown that the stochastic variability of these responses is similar to that predicted for a model with a multiplication factor of at least twenty-five.5. These results lead to the conclusion that the processes responsible for visual responses incorporate some form of amplification. This conclusion may prove useful for identifying the physical mechanisms underlying the transducer action of visual cells.

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