320 research outputs found
In vivo monitoring of human intestinal ischaemia: An on-line rapid sampling microdialysis biosensor system
The primary aim of this thesis was to monitor in vivo intestinal ischemia using rapid
sampling on-line microdialysis.
A new variant of a clinical assay system was developed for use in gastrointestinal surgery.
The assay could process on-line microdialysis samples for glucose and lactate
concentrations at 30 seconds intervals in the concentration range of 25 μM to 30 mM.
Intramural human bowel ischaemia was monitored intra-operatively in a clinical
collaboration with Prof. Darzi and Prof. Hanna in St. Maryʼs Hospital, London using a
microdialysis probe implantation technique devised by Mr. Samer Deeba. Dialysate levels
stabilised within 10-15 minutes following implantation of the CMA 62 microdialysis probe.
Clipping of arteries feeding the gastrointestinal tissue to be resected, did not lead to an
immediate change in dialysate levels, but a fall in glucose and rise in lactate delayed by 17
± 2 minutes, n=9. This suggests an additional pool of glucose availability in the bowel, and
indicates a possible therapeutic window during bowel surgery.
Parallel experimental work was carried out in swine model in the surgical labs of the
healthcare company Tyco (Covidien) in Paris. Rapid sampling microdialysis was used to
examine the effect of total ischaemia on an anastomosis site. The anastomotic site was
devascularised by clamping the mesentery of both sides. Here the tissue reacted to
ischaemia immediately, 5 minutes following clamping of feeding artery, compared with a
healthy human bowel, suggesting that the additional glucose pool was unavailable in this
situation. Physiological variable effects were studied to investigate further any difference
with respect to the human in pig bowel physiology, which were not found. The no-net-flux
method of in vivo recovery was used to determine the extracellular levels of glucose (0.47 ±
0.05 mM) in the intramural pig bowel. These were substantially lower than blood glucose
values, representing a 10% of plasma levels and suggest a difference with human bowel.
Finally, 7 patients were monitored after abdominal aortic aneurism repair surgery, for up to
2 days in the intensive care unit, to detect the possible on-set of ischaemia as a
complication of inferior mesenteric artery occlusion. Basal microdialysis levels at 3.98 ±
0.75 mM for glucose and 1.38 ± 0.20 mM for lactate agreed well with those measured
acutely during surgery, and were not sensitive to changes in plasma values. The
lactate/glucose ratio between 1-2 days post-implantation was typically between 0.5-1.0
again similar to the ratio found intra-operatively. This validates the use of microdialysis
intra-operatively and confirms the importance of this ratio. An in vivo calibration was
performed in one patient with the variable flow rate method providing extracellular levels for
glucose (5.8 ± 0.4 mM) and lactate (3.3 ± 0.2 mM) in intramural human bowel. These agree
well with measured blood glucose values. Although major ischaemic failure was not seen in
these patients, transient ischaemic events lasting 40 minutes and characterised by a
lactate/glucose ratio increase to 2 were noticed. Finally, a quasi-periodic oscillatory pattern
with inverse changes in glucose and lactate was observed during these patientsʼ
monitoring. This was ascribed to gut peristalsis
Leading proactivity in innovative startups: a moderated mediation model
Producción CientíficaDespite the growing research interest in proactivity, little is known about the relational mechanisms that cultivate individuals’ proactivity in the workplace. This research aims to explore the leader–follower relational mechanisms leading to employee proactive performance in innovative startups. The sample consisted of 83 employees from eleven startups. Conditional process modeling was conducted to explore the background relational mechanisms of employee proactive performance. Employees with upward psychological safety (who felt safe to speak up and contribute in front of their leaders) were willing to go beyond their formal roles and job descriptions for the sake of the firm (challenging role orientation). In turn, this orientation predicted self-directed efforts and initiated better ways of doing their job (proactive performance). Under high levels of perceived uncertainty, upward psychological safety was a stronger predictor of proactive performance through a challenging role orientation. This study reveals that upward psychological safety is critical for enhancing employee proactivity at work, particularly under high uncertainty
Efectos de los métodos de enseñanza innovadores en el rendimiento académico de los estudiantes: un estudio empírico sobre la contabilidad financiera
[ES]La implantación en España del Espacio
Europeo de Educación Superior ha supuesto
un cambio sustancial en las prácticas
tradicionales de la educación universitaria,
introduciendo importantes modificaciones
tanto en la metodología de la enseñanza
como en los criterios de evaluación.
El objetivo de este trabajo es determinar
si existe una relación entre la metodología
y el sistema de evaluación utilizado y los
resultados obtenidos por los alumnos,
diferenciando años académicos en los que se
aplican diferentes metodologías en el marco de la filosofía ECTS. Para ello, este trabajo
se centra en los resultados obtenidos en la
asignatura de Contabilidad Financiera, que
se encuentra en el primer curso del Grado en
Administración y Dirección de Empresas. En
primer lugar, se realiza una descripción de la
guía electrónica, mostrando la metodología
de enseñanza seguida por la asignatura. A
continuación, se muestran los resultados de
la investigación, el análisis de las relaciones
entre la metodología aplicada y los resultados
logrados mediante el uso de tablas de
contingencia y la prueba chi-cuadrado de
Pearson
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