Exponential Growth of Particle Number far from the Parametric Resonance Regime

Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields $\chi$ and the inflaton $\phi$, or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian $-g M_{pl}\phi\chi^2$. However, for the interaction Lagrangian $-g^2\phi^2\chi^2$, our formalism shows that in the large coupling limit there can only be exponential particle production when $\phi$ crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields $\chi$ and the inflaton $\phi$, or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian $-g M_{pl}\phi\chi^2$. However, for the interaction Lagrangian $-g^2\phi^2\chi^2$, our formalism shows that in the large coupling limit there can only be exponential particle production when $\phi$ crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields $\chi$ and the inflaton $\phi$, or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian $-g M_{pl}\phi\chi^2$. However, for the interaction Lagrangian $-g^2\phi^2\chi^2$, our formalism shows that in the large coupling limit there can only be exponential particle production when $\phi$ crosses 0.Parametric resonance has received a considerable amount of interest as a good mathematical model to describe the initial stages of the reheating phase (matter creation) in inflationary cosmology. It is also known that exponential particle creation can occur in situations which do not fall in the parametric resonance regime characterized by oscillations of the inflaton field about its minimum. Here we present a new analytical approach to exponential particle production which can occur when the inflaton is far from the minimum of its potential. Crucial for this effect is a term in the equation of motion which acts like a negative mass square term, as occurs for tachyonic preheating and negative coupling particle production. Our techniques apply in models with a strong coupling between matter fields $\chi$ and the inflaton $\phi$, or in some models in which the inflaton has a large amplitude of oscillation. Note that our analysis yields results which are quite model dependent. Exponential growth occurs in a model with interaction Lagrangian $-g M_{pl}\phi\chi^2$. However, for the interaction Lagrangian $-g^2\phi^2\chi^2$, our formalism shows that in the large coupling limit there can only be exponential particle production when $\phi$ crosses 0

Choque séptico por Pseudomonas aeruginosa associado a éctima gangrenosa em criança com agamaglobulinemia

Ecthyma gangrenosum (EG) due to Pseudomonas aeruginosa is a rare and invasive infection that can be associated with agammaglobulinemia. The cornerstone of the treatment is based on prompt recognition with appropriate antibiotic coverage and intravenous immunoglobulin. The authors report a case of EG emphasizing the clinical and therapeutic aspects of this condition.Éctima Gangrenosa (EG) por Pseudomonas aeruginosa é uma infecção rara e invasiva que pode ser associada com agamaglobulinemia. O tratamento fundamental é baseado no pronto reconhecimento com cobertura de antibiótico apropriada e imunoglobulina intravenosa. Os autores relatam caso de EG dando ênfase aos aspectos clínicos e terapêuticos desta condição

Sepse e meningite neonatal por Neisseria meningitidis: relato de caso

OBJECTIVE: To report a full-term newborn infant that developed a sepsis associated to meningitis caused by Neisseria meningitidis serogroup C on the 14th day of life. CASE DESCRIPTION: The patient was a term female infant, born to a mother with Systemic Lupus Erythematosus, with birth weight of 2,610g, Apgar Score 1, 4 and 8, who needed mechanical ventilation for 24 hours. On the 7th day of life, the neonate was discharged from the hospital with good overall condition. On the 15th day of life, the newborn infant presented fever and respiratory failure. The cerebrospinal fluid showed 1042 cells/mm&sup3;, with neutrophilic predominance, protein of 435 mg/dL, and glucose < 10 mg/dL. The blood and the cerebrospinal fluid cultures were positive for Neisseria meningitidis serogroup C. The neonate was hospitalized, needing mechanical ventilation and vasoactive drugs, and received 21 days of crystalline penicillin. After hospital discharge, there were no signs of neurological sequels and the infant was able to be breastfed. The case report presents a unique situation: an uncommon etiology of neonatal meningitis and favorable evolution, despite neurological sequels reported in the literature. This report emphasizes the need to prevent the premature exposure of newborn infants to pathological agents, especially if they presented birth injuries and/or are preterm, due to their lack of immunological capacity.OBJETIVO: Relatar o caso de um recém-nascido de termo que apresentou no 14º dia de vida sepse associada à meningite, cujo agente etiológico foi a Neisseria meningitidis sorotipo C. DESCRIÇÃO DO CASO: recém-nascido de termo, cuja mãe é portadora de lupus eritematoso sistêmico, feminino, peso de nascimento de 2610g, Escala de Apgar 1, 4 e 8, sendo intubado e ventilado por 24 horas. Recebeu alta no 7º dia de vida em boas condições. No 15º dia de vida apresentou febre e desconforto respiratório. O líquido cefalorraquidiano mostrou 1042 células/mm&sup3;, com predomínio de neutrófilos, proteinorraquia de 435 mg/dL e glicorraquia < 10 mg/dL; a bacterioscopia revelou a presença de diplococos. Foi internado na Terapia Intensiva Neonatal, necessitou de ventilação mecânica e de drogas vasoativas. A hemocultura e a cultura do líquido cefalorraquidiano foram positivas para Neisseria meningitidis C. O recém-nascido foi tratado por 21 dias com penicilina cristalina. Recebeu alta hospitalar em boas condições, em aleitamento materno exclusivo e sem seqüelas neurológicas. O caso descrito apresenta como peculiaridades: etiologia incomum de meningite neonatal e evolução favorável, apesar dos relatos em literatura mostrarem seqüelas neurológicas. Destaca-se ainda, a necessidade de enfatizar a não exposição precoce do recém-nascido, especialmente se tiver tido agravos ao nascimento ou for prematuro, devido à sua inexperiência imunológica

Complicações de aspiração de corpo estranho traqueobrônquico em crianças: relato de 5 casos e revisão da literatura

Aspiração de corpo estranho em via áerea é uma das principais causas de morte em crianças, especialmente nas menores que 3 anos de idade. A aspiração do corpo estranho pode causar um amplo espectro de sintomas, e o diagnóstico precoce é altamente associado com o sucesso da retirada do material inalado. Apesar dos grandes avanços nos procedimentos endoscópicos e anestésicos, um grande número de dificuldades e complicações ainda estão presentes nesta situação clínica. Neste estudo, descrevemos 5 casos de sérias complicações agudas, incluindo pneumomediatismo, pneumotórax, atelectasia total, migração do corpo estranho e necessidade de toracotomia, em crianças admitidas em nosso Centro de Terapia Intensiva em 1999 e 2000, situações essas que poderiam ser prevenidas com reconhecimento precoce e rápida intervenção terapêutica.Foreign body aspiration (FBA) is one of leading causes of death in children, especially among those younger than 3 years of age. The inhalation of a foreign body may cause a wide variety of symptoms, and early diagnosis is highly associated with the successful removal of the inhaled foreign material. Despite the great advances in endoscopic procedures and anesthesia, a large number of difficulties and complications still result from foreign body aspiration. We describe 5 cases of serious acute complications following aspiration of foreign bodies that became lodged in the tracheobronchial tree, including pneumomediastinum, pneumothorax, total atelectasis, foreign body dislodgment, and need for thoracotomy in children admitted into our intensive care unit in 1999 and 2000; these were all situations that could have been prevented with early recognition and prompt therapeutic intervention

Caracterização dos recém-nascidos com hidropisia fetal não imune admitidos em uma unidade neonatal de terapia intensiva

PURPOSE: To determine the incidence and characteristics of nonimmune hydrops fetalis in the newborn population. METHOD: A retrospective study of the period between 1996 and 2000, including all newborns with a prenatal or early neonatal diagnosis of nonimmune hydrops fetalis, based on clinical history, physical examination, and laboratory evaluation. The following were analyzed: prenatal follow-up, delivery type, gender, birth weight, gestational age, presence of perinatal asphyxia, nutritional classification, etiopathic diagnosis, length of hospital stay, mortality, and age at death. RESULTS: A total of 47 newborns with hydrops fetalis (0.42% of live births), 18 (38.3%) with the immune form and 29 (61.7%) with the nonimmune form, were selected for study. The incidence of nonimmune hydrops fetalis was 1 per 414 neonates. Data was obtained from 21 newborns, with the following characteristics: 19 (90.5%) were suspected from prenatal diagnosis, 18 (85.7%) were born by cesarean delivery, 15 (71.4%) were female, and 10 (47.6%) were asphyxiated. The average weight was 2665.9 g, and the average gestational age was 35 3/7 weeks; 14 (66.6%) were preterm; 18 (85.0 %) appropriate delivery time; and 3 (14.3%) were large for gestational age. The etiopathic diagnosis was determined for 62%, which included cardiovascular (19.0%), infectious (9.5%), placental (4.8%), hematologic (4.7%), genitourinary (4.8%), and tumoral causes (4.8%), and there was a combination of causes in 9.5%. The etiology was classified as idiopathic in 38%. The length of hospital stay was 26.6 &plusmn; 23.6 days, and the mortality rate was 52.4%. CONCLUSIONS: The establishment of a suitable etiopathic diagnosis associated with prenatal detection of nonimmune hydrops fetalis can be an important step in reducing the neonatal mortality rate from this condition.OBJETIVOS: Determinar a incidência e caracterizar a população de recém-nascidos com hidropisia fetal não imune. MÉTODO: Estudo retrospectivo, referente ao período de 1996 a 2000, incluindo todos os recém-nascidos com diagnóstico antenatal ou neonatal, com base na história clínica, exame físico e avaliação laboratorial. Foram analisados: seguimento pré-natal, tipo de parto, sexo, peso de nascimento, idade gestacional, presença de asfixia perinatal, classificação nutricional, diagnóstico etiopatogênico, tempo de internação, mortalidade, idade do óbito. RESULTADOS: Foram selecionados 47 recém-nascidos com hidropisia fetal (0,42% dos nascidos vivos), 18 (38,3%) com a forma imune e 29(61,7%) com a não imune. A incidência de hidropisia fetal não imune foi de 1:414 nascidos vivos. Obtiveram-se dados de 21 recém-nascidos destes, 19 (90,5%) apresentavam suspeita diag nostico antenatal, 18 (85,7%) nasceram de parto cesariano; 15 (71,4%) eram do sexo feminino; 10 (47,6%) foram asfixiados. O peso médio foi 2665,9g, e a idade gestacional média de 35 3/7 sem, 14 (66,6%) pré-termo; 18 (85,7%) adequados e 3 (14,3%) grandes para idade gestacional. O diagnóstico etiopatogênico foi realizado em 62% dos recém-nascidos, sendo decorrente de causas cardiovasculares (19%), infecciosas (9,5%), placentária (4,76%), hematológicas (4,76,%), gênito-urinária (4,76%), tumoral (4,76%) e houve associação de causas em 9,5%. A etiologia foi classificada em idiopática em 38%. O tempo de internação foi de 26,6 dias &plusmn; 23,6 e a mortalidade de 52,4%. CONCLUSÕES: O estabelecimento de um correto diagnóstico etiopatogênico, associado à detecção antenatal da hidropisia fetal não imune, constitui elemento importante para uma redução da mortalidade neonatal decorrente desta grave doença

Hospital Malnutrition and Inflammatory Response in Critically Ill Children and Adolescents Admitted to a Tertiary Intensive Care Unit

Critical illness has a major impact on the nutritional status of both children and adults. A retrospective study was conducted to evaluate the incidence of hospital malnutrition at a pediatric tertiary intensive care unit (PICU). Serum concentrations of IL-6 in subgroups of well-nourished and malnourished patients were also evaluated in an attempt to identify those with a potential nutritional risk