Encoding integers and rationals on neuromorphic computers using virtual neuron

Neuromorphic computers emulate the human brain while being extremely power efficient for computing tasks. In fact, they are poised to be critical for energy-efficient computing in the future. Neuromorphic computers are primarily used in spiking neural network-based machine learning applications. However, they are known to be Turing-complete, and in theory can perform all general-purpose computation. One of the biggest bottlenecks in realizing general-purpose computations on neuromorphic computers today is the inability to efficiently encode data on the neuromorphic computers. To fully realize the potential of neuromorphic computers for energy-efficient general-purpose computing, efficient mechanisms must be devised for encoding numbers. Current encoding mechanisms (e.g., binning, rate-based encoding, and time-based encoding) have limited applicability and are not suited for general-purpose computation. In this paper, we present the virtual neuron abstraction as a mechanism for encoding and adding integers and rational numbers by using spiking neural network primitives. We evaluate the performance of the virtual neuron on physical and simulated neuromorphic hardware. We estimate that the virtual neuron could perform an addition operation using just 23 nJ of energy on average with a mixed-signal, memristor-based neuromorphic processor. We also demonstrate the utility of the virtual neuron by using it in some of the μ-recursive functions, which are the building blocks of general-purpose computation.

Clinical outcomes after increasing bladder outlet resistance without augmentation cystoplasty in neurogenic bladder

INTRODUCTION

Patients with neurogenic bladder (NGB) and urinary incontinence (UI) due to low bladder outlet resistance may require bladder neck procedures (BNPs) to achieve continence. These patients may also have reduced bladder capacity and or elevated detrusor storage pressures that require augmentation cystoplasty (AC). AC is not without complications that include risks for bladder rupture, urolithiasis, urinary tract infections and metabolic issues. Avoidance of AC would be helpful in patients with neurogenic urinary incontinence that have safe bladder parameters in the setting of low bladder outlet resistance.

OBJECTIVE

To determine if pre-operative urodynamics could select children with NGBs and UI for isolated BNPs without AC. Additionally we sought to determine the safety of BNPs without AC and future need of AC with long-term follow-up.

STUDY DESIGN

This is an IRB-approved retrospective analysis of all patients undergoing BNPs for management of neurogenic UI over a 17-year period. We separated these BNP patients into two groups: No AC + BNP (Group 1) vs. AC + BNP (Group 2). Our primary analyses focused on postoperative outcomes for patients in Group 1. Outcomes assessed included additional surgical procedures, urodynamic changes, development of CKD, new hydronephrosis (HDN) and vesicoureteral reflux (VUR). Secondary analysis included the timeline for the development of any bladder deterioration that necessitated AC in Group 1.

RESULTS

93 patients underwent BNP at a mean age of 10.8 years. Thirty did not have AC at the time of surgery (Group 1). These children had larger (p < 0.001) and more compliant (p < 0.001) bladders than Group 2 having simultaneous augmentation. At 6 years mean follow-up in Group 1 patients, three developed new reflux and three had new hydronephrosis. Nine (30%) had additional continence procedures. Twelve required (40%) AC at a mean of 23 months after the initial BNP. No patients had AC after 5 years. Detrusor end filling pressure increased 14.8 cm H2O (p = 0.028) and expected bladder capacity decreased 26.1% (p = 0.005) after isolated BNP.

DISCUSSION

We found that from our cohort of patients who had normal bladder compliance and normal/near normal expected capacity preoperatively 40% required subsequent AC. We were unable to find pre-operative clinical parameters which predicted failure or conversion to AC. We found that 43.3% of our BNP without AC patients had no subsequent invasive procedures with mean 6-year follow-up. We found that none of our patients developed any degree of CKD. Finally, we found that the majority of patients that converted to AC after their BNP did so within the first 2 years after their initial BNP and no patients required augmentation 5 years post their initial BNP. This data validates that these patients require very strict follow up, particularly in the first 5 years after surgery.

CONCLUSIONS

BNP without AC is safe in only a few selected patients with NGB. Despite preoperative selection, there are significant changes in bladder dynamics and 40% required subsequent augmentation. Bladder deterioration occurs early and generally in the first 2 years. Since there are no apparent reliable pre-operative variables predicting the need for subsequent AC, parents should be counseled regarding vigilant post-operative follow-up.

Seasonal plasticity in photoprotection modulates UV-induced hsp gene expression in copepods from a clear lake

Zooplankton from clear alpine lakes is exposed to stressful levels of solar UV radiation (UVR). As these pelagic organisms experience high UVR and large changes in solar radiation conditions between ice-free and ice-cover periods, they have evolved various strategies to minimize UVR exposure and damage. Here, we studied the relation between photoprotection levels (mycosporine-like amino acids, carotenoids), antioxidant capacities, and gene expression of heat shock proteins (hsps) as indicator of stress in the copepod Cyclops abyssorum tatricus during the course of a year. Expression of hsp60, hsp70, and hsp90 was measured in the field (baseline expression [BE]) and after UVR exposure in the laboratory. The BE differed among genes and seasons (hsp60: high during summer, hsp70 and hsp90: high during the ice-cover period). The gene expression of hsp70 was upregulated after exposure to UVR (up to 5.2-fold change), while hsp60 and hsp90 were only constitutively expressed. A strong seasonal pattern was found in the photoprotective compounds and antioxidant capacities, with highest levels during the ice-free period. The extent of upregulation of hsp70 gene expression increased with decreasing photoprotection levels and peaked 24 h post UVR exposure (9.6-fold change) at the time of lowest photoprotection (February). Our data suggest that hsp70 gene expression is modulated by seasonal plasticity in photoprotection. This ability of adequate stress response is essential for survival in highly variable ecosystems such as alpine lakes.

Poison hemlock (Conium maculatum L.)

One of the most poisonous species amongst higher plants is Conium maculatum. It is a very common nitrophile weed species, belonging to the Apiaceae (formerly Umbelliferae) family. It contains some piperidine alkaloids (coniine, N-methyl-coniine, conhydrine, pseudoconhydrine, gamma-coniceine), which are formed by the cyclisation of an eight-carbon chain derived from four acetate units. gamma-Coniceine is the precursor of the other hemlock alkaloids. All vegetative organs, flowers and fruits contain alkaloids. The concentrations (both absolute and relative) of the different alkaloids depend on plant varieties, on ecological conditions and on the age of the plant. The characteristic biological effects of the plants are summarised on cattle, sheep, goat, swine, rabbit, elk, birds and insects and the symptoms of the human toxicosis (some cases of poisonings) are discussed according to the literature data. The general symptoms of hemlock poisoning are effects on nervous system (stimulation followed by paralysis of motor nerve endings and CNS stimulation and later depression), vomiting, trembling, problems in movement, slow and weak later rapid pulse, rapid respiration, salivation, urination, nausea, convulsions, coma and death.

[Jugular lymph node metastasis of papillary thyroid gland carcinoma 10 years later]

We present a patient with occult papillary thyroid carcinoma, in whom a single nodal metastasis had been excised. Ten years later a nodal recurrence was diagnosed by ultrasound and fine needle aspiration cytology. The diagnosis of recurrence was erroneous, and we discuss the differential diagnostic problems, the natural course, and the adequate treatment of occult papillary microcarcinoma.

Characterization of the alpha(2)-adrenoceptor subtype, which functions as alpha(2)-autoreceptor in human neocortex

The pharmacological properties of the alpha(2)-adrenergic receptors regulating the release of norepinephrine were investigated in human neocortex. Slices were preincubated with [(3)H]norepinephrine, superfused under blockade of transmitter reuptake, and stimulated electrically. First, the autoinhibitory circuit of [(3)H]norepinephrine release was analyzed quantitatively by estimation of the K(d) of norepinephrine at the alpha(2)-autoreceptor (10(-7.99) M), the concentration of the endogenous transmitter causing this autoinhibition at a stimulation frequency of 3 Hz (10(-7.61) M), and the maximum inhibition obtainable through the autoreceptor (83%). Second, antagonist pK(b) values of nine antagonists were determined by using their pEC(50) values (negative logarithms of antagonist concentrations that increased the electrically evoked overflow of tritium by 50%) against the release-inhibiting effect of the endogenous transmitter. When compared with binding or functional data from the literature, the pK(b) values correlated best with the antagonist affinities at alpha(2A) binding sites. In contrast, the correlations with alpha(2B), alpha(2C), and alpha(2D) sites were not as good. It is concluded that in human neocortex prejunctional autoreceptors are alpha(2A).

Plant cyanogenic glycosides

The cyanogenic glycosides belong to the products of secondary metabolism, to the natural products of plants. These compounds are composed of an alpha-hydroxynitrile type aglycone and of a sugar moiety (mostly D-glucose). The distribution of the cyanogenic glycosides (CGs) in the plant kingdom is relatively wide, the number of CG-containing taxa is at least 2500, and a lot of such taxa belong to families Fabaceae, Rosaceae, Linaceae, Compositae and others. Different methods of determination are discussed (including the indirect classical photometrical and the new direct chromatographic ones). The genetic control of cyanogenesis has no unique mechanism, the plants show variation in the amount of the produced HCN. The production of HCN depends on both the biosynthesis of CGs and on the existence (or absence) of its degrading enzymes. The biosynthetic precursors of the CGs are different L-amino acids, these are hydroxylated then the N-hydroxylamino acids are converted to aldoximes, these are turned into nitriles. The last ones are hydroxylated to alpha-hydroxynitriles and then they are glycosilated to CGs. The generation of HCN from CGs is a two step process involving a deglycosilation and a cleavage of the molecule (regulated by beta-glucosidase and alpha-hydroxynitrilase). The tissue level compartmentalisation of CGs and their hydrolysing enzymes prevents large-scale hydrolysis in intact plant tissue. The actual level of CGs is determined by various factors both developmental and ecological ones, which are reviewed too. The last part of the present work demonstrates the biological roles of CGs in plant physiological processes and in plant defence mechanisms as well. The effect of CGs (HCN) on different animals, the symptoms of poisonings are discussed to cows, sheep, donkeys, horses and chicks. Finally, the poisonous effects of cassava (Manihot esculenta) roots are summarised on experimental animals and on the human organism.

The role of fungi in the carbon- and nitrogen cycles

The green plants fix a great amount of carbon (CO2) and accumulate as different organic molecules mainly as lignocelluloses. Fungi belong not only to an independent group of Eukaryots but they have – in most of the cases – a specific biochemical, physiological ability to decompose organic molecules, to produce substrates of respiration and to mineralize these for the biological cycles of ecosystem.

Study of fossil tracks due to 50 < or = Z < or = 92 galactic cosmic ray nuclei in meteoritic crystals: results and perspectives

A new approach to the problem of investigation of charge and energy spectra of ultra heavy Galactic cosmic ray nuclei, based on fossil track study of extraterrestrial olivine crystals has been developed. The results of an investigation of ultra heavy Galactic cosmic ray nuclei (Z=50-92) in meteoritic olivine crystals are presented. The technique was based on calibration of olivine crystals with accelerated Xe, Au, Pb and U ions and well-controlled partial annealing of "fresh" and "fossil" tracks. It allows us to determine the charge spectra and abundances of cosmic ray nuclei based on fossil track length study in meteoritic and Moon crystals. The comparative studies of the spectra of "fossil' tracks and tracks due to 208Pb and 238U nuclei have shown that the group of 210 micrometers "fossil" tracks, first observed in 1980 at JINR is due to Th-U nuclei-products of recent r-process nucleosynthesis in our Galaxy. The method in principle allows one to resolve Pt-Pb peaks in fossil tracks, to establish the upper limit of the abundance of Z>110 nuclei in the Galactic cosmic rays at the level < or = 10(-3) to the abundance of actinide nuclei and to get information on the history of Z>50 cosmic ray nuclei in time interval up to 220 M.Y.

Toxins of Amanita phalloides

The most poisonous mushroom toxins are produced by Amanita phalloides (death cap). The occurrence and chemistry of three groups of toxins (amatoxins, phallotoxins and virotoxins) are summarized. The concentration and distribution of toxins in certain species are variable, with the young fruit body containing lower, and the well-developed fungus higher concentrations, but there is a high variability among specimens collected in the same region. Regarding phallotoxins, the volva (the ring) is the most poisonous. The most important biochemical effect of amatoxins is the inhibition of RNA polymerases (especially polymerase II). This interaction leads to a tight complex and the inhibition is of a non-competitive type. Non-mammalian polymerases show little sensitivity to amanitins. The amatoxins cause necrosis of the liver, also partly in the kidney, with the cellular changes causing the fragmentation and segregation of all nuclear components. Various groups of somatic cells of emanation resistance have been isolated, including from a mutant of Drosophila melanogaster. The phallotoxins stimulate the polymerization of G-actin and stabilize the F-actin filaments. The interaction of phallotoxins occurs via the small, 15-membered ring, on the left side of the spatial formula. The symptoms of human poisoning and the changes in toxin concentrations in different organs are summarized. Conventional therapy includes: (1) stabilization of patient's condition with the correction of hypoglycaemia and electrolytes; (2) decontamination; and (3) chemotherapy with different compounds. Finally, certain antagonists and protective compounds are reviewed, bearing in mind that today these have more of a theoretical than a practical role.

Popliteal artery compression and force of active plantar flexion in young healthy volunteers

PURPOSE

To define the prevalence of popliteal artery occlusion during active plantar flexion in normally active and highly trained young volunteers by measuring plantar flexion force and to assess the force level associated with popliteal artery occlusion.

METHODS

Eighty-four limbs of 42 healthy subjects were studied. Eighteen subjects were highly trained athletes, and 24 were normally active persons. Plantar flexion was progressively performed in prone position against a scale. Plantar flexion force was measured in kilograms. After determination of the maximum strength (Pmax) of plantar flexion force, the level necessary to occlude the popliteal artery (Poccl) was assessed by continuously monitoring that vessel using color duplex sonography.

RESULTS

Occlusion of the popliteal artery during plantar flexion was observed in 88.1% of the subjects and 77.4% of the limbs. No significant differences in prevalence were found between athletes and normally active subjects. The popliteal artery occluded at a mean plantar flexion force of 45.1 +/- 11.5 kg, which corresponded with 70.1% +/- 16.8% of the maximum force exerted during the provocation test. Poccl was not significantly different between lower limbs of athletes and nonathletes. Although in lower limbs of athletes the popliteal artery occluded at a significantly lower relative force as compared with normally active subjects (65.6% +/- 17.4% vs 74.5% +/- 17.4% of Pmax; p < 0.02), the difference was a result of two extremely low values found in a female athlete.

CONCLUSION

Positional occlusion of the popliteal artery during active plantar flexion is commonly found in young healthy volunteers. Prevalence of the phenomenon depends on the force level exerted during active plantar flexion. Popliteal artery occlusion during active plantar flexion is not more frequent in athletes and occurs at a similar force level than in normally active subjects.

Lung perfusion patterns after bidirectional cavopulmonary anastomosis (Hemi-Fontan procedure)

Perfusion lung scans were performed immediately prior to Fontan procedure in 45 patients with a functional single ventricle who underwent the hemi-Fontan procedure as an intermediate stage between the initial palliative shunt procedure and the final complete Fontan anastomosis. Symmetric pulmonary blood flow (PBF) distribution was found in 27% of patients, whereas moderately to severely abnormal PBF distribution was found in 35% of patients. The achieved systemic aortic saturation following the hemi-Fontan procedure was not affected by these abnormalities.

Effect of volume unloading surgery on coronary flow dynamics in patients with aortic atresia

OBJECTIVES

The objectives of this study were to define physiologic effects on and a clinical correlate to coronary blood flow during volume unloading surgery in patients with aortic atresia.

METHODS

Twenty-two patients with aortic atresia (group I, 13 patients with stage I reconstruction undergoing hemi-Fontan operation; group II, 9 patients with hemi-Fontan undergoing Fontan operation) underwent perioperative transesophageal echocardiography. Doppler spectral patterns, peak velocity, velocity time integral, and blood flow in the native ascending aorta were measured. Preoperative hemodynamics and postoperative clinical data were analyzed. Significance was defined as p < 0.05.

RESULTS

Higher values of coronary blood flow (982.9 +/- 321.7 vs 548.6 +/- 333.8 ml/min per square meter), velocity time integral (20.7 +/- 5.6 vs 12.6 +/- 4.0 cm), and peak velocity (96.1 +/- 21.4 vs 51.0 +/- 18.2 cm/sec) were found before operation in group I than after operation and in group II at both times. Flow changed from predominately systolic in preoperative group I to both systolic and diastolic after operation and in group II. Before operation in groups I and II, a number of hemodynamic parameters such as superior vena cava oxygen saturation correlated with coronary blood flow dynamics. After operation in group II, urine output (r = 0.86) and central venous pressure (r = -0.85) correlated with coronary blood flow dynamics.

CONCLUSION

Coronary blood flow parameters were higher in group I as a result of the increased energy needs required to pump to two circulations. No changes were found in group II. A number of coronary blood flow parameters correlated with preoperative hemodynamics and postoperative clinical data. These parameters appear to be useful in assessing the performance status of the myocardium after the Fontan operation, consistent with the notion that myocardial perfusion relates directly to ventricular function.

[Mineral and amino acid contents of edible, cultivated shii-take mushrooms (Lentinus edodes)]

World wide about 200,000 tons of shii-take mushrooms (Lentinus edodes) are produced per year. Different positive biological effects are known (anticarcinogenic, anticholesterol, immunostimulating effects), but the mineral contents and amino acid composition of caps and stipes are still little investigated. The concentrations of minerals are in general lower than those in the cultivated white mushroom (Agaricus bisporus) and in the oyster mushroom (Pleurotus ostreatus). The greatest differences are found in the concentrations of potassium, phosphorus, calcium, copper, strontium, manganese and zinc. The concentrations are higher in caps than in stipes. The total amino acid content is 15.24% in caps and 11.35% in stipes (dry matter) and thus in general half of the concentration of cultivated champignon. The amounts of Phe, Gly, His, Arg, Ile and Met are relative higher than in Agaricus fruit bodies.

[Chemical composition of seeds and testa of Vicia faba L]

Different chemical components were analysed in the seeds and in testa of Vicia faba. The seeds contain a relatively high crude protein (27.5%), a low crude fat (3.36%) content; and the lignin concentration is low (2.65%). The testa of the seeds has a very high fibre concentration and is a significant Ca-source (1.86 g/kg). The higher macroelement concentrations in the seeds were measured from K, P and Mg. The main microelements (Fe, Mn, Cu, Zn) have significant higher concentrations in the seed than in the testa. The amino acid composition of seeds is positive (compared to data of white lupine), the rate of essential amino acids is good. The concentrations of the examined antinutritive organic constituents, especially of alkaloids, are low. On the basis of chemical analysis, the production and utilisation of seeds of Vicia faba is recommended.

[The copper, manganese and zinc content of some edible mushrooms]

Fifty six samples of edible, wide-spread species of higher fungi were analysed for copper-, manganese- and zinc-contents. The average copper concentration of the samples is high (56.16 mg/kg dry mass) as compared to the green plants. Some groups of fungi (Agaricus and Macrolepiota species) are considerable copper-accumulators (until 226 mg/kg DM). Pronounced accumulation of manganese was reported in the case of Lepista nebularis and Pluteus atricapillus. The zinc-content of fungi (average: 104.1 mg/kg DM, between 7.71 mg/kg (Lepista nebularis) and 194.3 mg/kg (Agaricus silvaticus) is relatively balanced, accumulation were not established.

[Minerals and amino acids in the grains of the recently cultivated "pseudo-cereal" species Amaranthus hypochondriacus]

The mineral elements and the amino acids in seeds of cultivated Amaranthus hypochondriacus were studied. The following conclusions can be made: 1. The contents of minerals in Amaranthus seed are similar to those of wheat and (except of a few elements: P, K) of pea. The habitats of plants, especially the soil conditions effect importantly on minerals. -2. The total amino acid content and mainly the rate of essential amino acids (lysine, arginine etc) are higher than those in seeds of wheat and maize and this fact create the importance of cultivation and utilisation of this plant. The cultivated Amaranthus species have favourable ecological properties (drought resistance, undemanding) too.

Data on arsenic and cadmium contents of some common mushrooms

The arsenic and cadmium contents of 88 samples of mushrooms were determined. The majority of samples have a very low (practically zero) arsenic level; however, significant accumulations were found in the Agaricus species and in Macrolepiota rhacodes (which is related to the Agaricaceae family) and in three Tricholomataceae species (Flammulina velutipes, Lepista nebularis and Clitocybe, inversa). The average cadmium content of all samples was 4.91 ppm (0.28-86 ppm) on a dry weight basis. The highest concentration (34.9 ppm) was found to be characteristic of genus Agaricus. The accumulation potential of genus Russula is lower, and it appears that this content is more characteristic in three sections (Ingratea, Heterophyllae and Xerampelinae), whereas the others have a low (normal) cadmium level. These data confirm that the accumulation ability is genetically coded, thus, only certain taxonomical groups of fungi play a toxicological role. Our data offer new information about the concentration of two toxic elements of particular mushroom species as well as in other taxonomic groups. These data are of great importance in view of toxicology, food chemistry and, partly, environmental protection.

[Potassium content of edible wild mushrooms]

The average potassium content of edible higher mushroom species is 34,35 g/kg-1 dry matter (SD: 12,91) and thus an important and valuable K-source for human diet. The K-concentration of mushrooms is relatively constant. An accumulation of potassium in the mushroom samples analysed was not found. This fact is confirmed by the results of other authors, too.

[Crude, digestible and indigestible fruit body proteins in oyster mushroom Pleurotus ostreatus]

Different kinds of protein (crude, digestible, non-digestible) were analysed in caps and stipe of Pleurotus ostreatus (oyster mushroom) in four phases of development. The phases examined were: a (cap diameter < 5 cm); B (diameter 5-8 cm); C (diameter, 8-10 cm) and D (diameter > 10 cm). The Pleurotus variety analysed (the cap and the stipe) has a relative high crude protein content, the main part of which is digestible (average, 92%). During the four stages of fruit body ripening, stage B was the best, with the highest crude and digestible protein concentrations. In stage D the highest non-digestible protein content was measured in the cap and stipe. These data can be used for optimal harvesting of fruit bodies of cultivated P. ostreatus.

[The amino acid composition of the edible Russula and Agaricus mushroom species]

The amino acid concentrations of six samples (five species) of the genus Russula and of seven samples (five species) of the genus Agaricus were determined. The Russula samples have significantly lower total amino acid concentrations (14.79% of the dry weight), than the Agaricus species (23.75%). Essential amino acids occur in both groups in appreciable concentrations: 48.9% of the total amino acid concentration for Russula and 46.4% for Agaricus. Between the cultivated varieties and the wild species of Agaricus are insignificant differences in the total amino acid concentration, but the quantities of certain essential amino acids were lower, whereas the concentration of Glu was higher in the wild species.

[Chemical composition of eight edible mushrooms]

A comparative analysis of crude protein, crude ash, phosphorus (P), potassium (K) and calcium (Ca) contents of 57 samples of eight common edible mushroom species was made. The most important protein sources were: Marasmius oreades and Lepista nebularis. Species of the Boletaceae formed an intermediate group, while relatively proteinless species were: Armillariella mellea and Cratarellus cornucopioides. The lowest crude protein content was established in Cantharellus cibarius. The ash contents varied more widely. The greatest P contents were measured in Lepista nebularis and Marasmius oreades but most mushrooms contained 6-7 gP/kg. The analysed mushroom samples contained 30-40 gK/kg dry weight and 0,2-0,3 gCa/kg. These analyses are important from the point of view of the nutritional role of mushrooms.

Noninvasive imaging of intraarterial baffles in infants and children

Baffles within the lumen of the pulmonary artery are created in (1) the Aubert procedure, a variation of the arterial switch favored by some surgeons when two major coronary ostia arise close to one another or when one coronary artery has an intramural course, and (2) the Takeuchi procedure, a technique applied to patients with anomalous origin of the left coronary from the pulmonary artery. In both operations, coronary artery transplantation is avoided; instead, an aorticopulmonary window is created and aortic blood is redirected by an intrapulmonary artery baffle into the coronary circulation. We imaged five patients with Aubert and 10 patients with Takeuchi procedures by use of ultrasound to assess the sequelae of such intraarterial baffles. All five Aubert patients were < 3 weeks old; the ages of the 10 Takeuchi patients ranged from 2 to 86 months. Two patients died early after surgery; the remaining 13 patients were observed for 3 to 83 months (median 46 months). In all 15 patients, the baffle geometry was visualized and the aorticopulmonary window was identified. In the six who had serial imaging, none developed aorticopulmonary window stenosis. In no patient was any peribaffle shunting detected. Supravalvar narrowing, caused by the baffle partially obstructing the neopulmonary artery, was observed in two of five Aubert patients; in only one of these has reoperation been performed. In one of the 10 Takeuchi patients supravalvar narrowing of the pulmonary artery (related to repair of coexistent tetralogy of Fallot) has developed and the patient has since undergone reoperation.