Silicon photonics: beating the bottleneck

The use of cascaded nonlinear silicon waveguides that function as 'time lenses' is providing new opportunities for generating and measuring ultrafast optical waveforms

The Influence of CO₂ Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic

This work extends our previous experimental studies of the chemistry of Titan’s atmosphere by atmospheric glow discharge. The Titan’s atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3)

Gastrostomia endoscópica em pacientes com cardiopatia complicada Percutaneous endoscopic gastrostomy in cardiologic complicated patients

Pacientes cardiopatas complicados com isquemia cerebral e insuficiência cardíaca necessitam terapia nutricional enteral prolongada por se apresentarem em situação de risco nutricional. Complicações advindas do uso prolongado da sonda nasoenteral poderiam ser evitadas com a execução da gastrostomia endoscópica. Esta é alternativa técnica para acesso ao tubo digestivo em nutrição enteral. O objetivo deste estudo foi avaliar o tempo de indicação para gastrostomia endoscópica em pacientes com nutrição enteral com uso de sonda nasoenteral e as principais complicações do procedimento. Doze pacientes foram submetidos a gastrostomia endoscópica, sendo oito do sexo masculino. A idade média foi de 62,42 + 22,10 anos. A indicação principal foi síndrome isquêmica cerebral após parada cardiorespiratória por patologia clínica (sete pacientes) ou cirurgia cardiovascular complicada (cinco). O tempo médio para indicação da gastrostomia endoscópica foi de 35,58 + 26,79 dias após introdução da nutrição enteral. Não houve intercorrências com o procedimento e, no período pós-operatório tardio, ocorreu infecção do orifício de inserção da gastrostomia endoscópica em um caso, resolvida com cuidados locais. Em conclusão, a gastrostomia endoscópica é técnica segura, com baixa incidência de complicações. Pode ser realizada em ambulatório, no leito do paciente, ou em centro de terapia intensiva e sua indicação deveria ser mais precoce.<br>Complicated cardiologic patients with brain ischemia and heart failure need long term enteral nutrition. Long term nasoenteral tuibe feeding may cause complications that could be avoided with percutaneous endoscopic gastrostomy. The aim of this study was to evaluate the indications for percutaneous endoscopic gastrostomy and its main complications. Twelve patients were submitted to percutaneous endoscopic gastrostomy (eight male) with main age of 62,42 ± 22,10 years old. Brain ischemia was the main indication of percutaneous endoscopic gastrostomy and occurred after 35,58 ± 26,79 days, after iniciated enteral nutrition. There were no complications during procedure. On late post operatory period there were local infection in one cases, treated with local care. In conclusion, percutaneous endoscopic gastrostomy is a secure technique with low incidence of complications and its indication should be earlier