Study of guided wave propagation on a plate between two solid bodies with imperfect contact conditions.

In this work, fundamental symmetric Lamb wave S0 mode is characterized in terms of its velocity variation as function of the interfacial conditions between solid bodies in contact. Imperfect contact conditions are numerically and experimentally determined by using ultrasonic Lamb wave propagation parameters. For the study, an experimental system was used, formed by two solid aluminum rods (25.4mm in diameter) axially loading a thin aluminum plate to control contact interfacial stiffness. The axially applied load on the aluminum plate was varied from 0MPa to 10MPa. Experimental Lamb wave signals were excited on the plate through two longitudinal contact transducers (1MHz of central frequency) using a pitch-catch configuration. Numerical simulations of contact conditions and Lamb wave propagation were performed through Finite Element Analysis (FEA) in commercial software, ANSYS 15®. Simulated Lamb wave signals were generated by means of a 5 cycles tone burst signals with different frequency values. Results indicate a velocity change in both, experimental and simulated Lamb wave signals as function of the applied load. Finally, a comparison between numerical results and experimental measurements was performed obtaining a good agreement.

[Elevated incidence of cognitive impairment in patients with asymptomatic carotid stenosis]. / Elevada incidencia de deterioro cognitivo en pacientes con estenosis carotidea asintomatica.

INTRODUCTION: Stroke is one of the main causes of mortality and functional disability in developed countries. Carotid stenosis (CS) is considered the reason for 20-30% of strokes. However, the studies that have gone into depth on the cognitive status of these patients are limited. AIM: To investigate the cognitive performance of CS patients and its relationship with clinical variables (carotid obstruction, lifestyle). PATIENTS AND METHODS: 33 CS patients were evaluated using a broad neuropsychological protocol, and were divided into two groups: symptomatic CS and asymptomatic CS. RESULTS: 50-57% of CS patients showed deficits in processing speed and visual memory (immediate recall). 41.9% showed altered performance in semantic fluency, whereas the percentage was 30% in digits subtest. The percentage of altered performance was 20-27% in verbal memory (learning curve, delayed recall) and visual memory (delayed recall). No significant differences were found between the symptomatic CS and asymptomatic CS groups. Cognitive performance correlated significantly with lifestyle scale factors, but not with the percentage of carotid obstruction. CONCLUSION: A high percentage of CS patients showed a clinically altered performance in different cognitive domains, regardless of suffering vascular neurological symptoms (symptomatic vs asymptomatic CS). A close relationship was found between lifestyle and cognitive status of CS patients.

TITLE: Elevada incidencia de deterioro cognitivo en pacientes con estenosis carotidea asintomatica.Introduccion. Los ictus se situan como una de las principales causas de mortalidad e incapacidad funcional en los paises desarrollados. La estenosis carotidea (EC) se considera la causa del 20-30% de los ictus. No obstante, los estudios que han profundizado en el estado cognitivo de estos pacientes son escasos. Objetivo. Estudiar el rendimiento cognitivo de pacientes con EC y su relacion con variables clinicas (obstruccion de la carotida, estilo de vida). Pacientes y metodos. Se evaluo a 33 pacientes con EC mediante un protocolo neuropsicologico amplio, distribuidos en dos grupos: EC sintomatica y EC asintomatica. Resultados. Un 50-57% de los pacientes con EC presento una ejecucion alterada en velocidad de procesamiento y memoria visual (recuerdo inmediato). Un 41,9% rindio de forma alterada en fluidez semantica, mientras que en el subtest de digitos el porcentaje fue del 30%. En la memoria verbal (curva de aprendizaje, recuerdo demorado) y la memoria visual (recuerdo demorado), el porcentaje de alterados fue del 20-27%. No se encontraron diferencias significativas entre los grupos de EC asintomatica y EC sintomatica. El rendimiento cognitivo correlaciono significativamente con los factores de la escala de estilo de vida, pero no con el porcentaje de obstruccion de la carotida. Conclusion. Un elevado porcentaje de los pacientes con EC presento un rendimiento clinicamente alterado en diferentes dominios cognitivos, con independencia de que hubieran experimentado o no sintomatologia neurologica vascular (EC asintomatica frente a sintomatica). Se encontro una estrecha relacion entre el estilo de vida y el estado cognitivo de los pacientes con EC.

Defensin like peptide from Panulirus argus relates structurally with beta defensin from vertebrates.

Naturally occurring antimicrobial peptides take place in the first line of host defense against pathogen as part of the humoral innate immune response. ß-defensins are among the most abundant antimicrobial peptides in mammals, and thought to be solely found in vertebrates until a recent report describing the cloning and sequencing of defensin like peptides in the spiny lobster Panulirus japonicus. In the current study, we cloned and sequenced two genes from the hemocytes of the spiny lobster Panulirus argus encoding for two isoforms of defensin-like peptides, thus confirming the presence of this protein in the Panulirus genus. The 44 amino acids mature peptides showed the conservation of cysteine pattern characterizing the ß-defensins, as well as known amino acids residues critical to exert their antimicrobial activity. They are also amphipathics, hydrophobics, and display an overall positive charge (+1) located at the C-terminus. The tertiary structure obtained by homology modeling indicated that likely conformations of lobster peptides are highly similar to ß-defensins from vertebrates. The phylogenetic study carried out by probabilistic methods confirmed the relation with ancestral ß-defensin from vertebrates. The finding of a putative defensin-like peptide in the expressed sequence tag (EST) of the lobster Homarus americanus with high homology with those of P. argus described in this study, would indicate the presence of this peptides in Palinuridae family. Taking into account all similarities between these peptides with ß-defensins from vertebrates, it is conceivable to further support the finding of a new family of ß-defensins in invertebrate.