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AbstractObjectives:Several studies, mostly from developed countries, have identified barriers and facilitators with regard to the uptake of health technology assessment (HTA). This study elicited, using best-worst scaling (BWS), what HTA experts in Colombia consider to be the most important barriers and facilitators in the use of HTA, and makes a comparison to results from the Netherlands.Methods:Two object case surveys (one for barriers, one for facilitators) were conducted among 18 experts (policymakers, health professionals, PhD students, senior HTA-researchers) from Colombia. Seven respondents were employees of the national HTA agency Instituto de Evaluación Tecnológica de Salud (IETS). In total, 22 barriers and 19 facilitators were included. In each choice task, participants were asked to choose the most and least important barrier/facilitator from a set of five. Hierarchical Bayes modeling was used to compute the mean relative importance scores (RIS) for each factor, and a subgroup analysis was conducted to assess differences between IETS and non-IETS respondents. The final ranking was further compared to the results from a similar study conducted in the Netherlands.Results:The three most important barriers (RIS >6.00) were “Inadequate presentation format”, “Absence of policy networks”, and “Insufficient legal support”. The six most important facilitators (RIS >6.00) were “Appropriate timing”, “Clear presentation format”, “Improving longstanding relation”, “Appropriate incentives”, “Sufficient qualified human resources”, and “Availability to relevant HTA research”. The perceived relevance of the barriers and facilitators differed slightly between IETS and non-IETS employees, while the differences between the rankings in Colombia and the Netherlands were substantial.Conclusion:The study suggests that barriers and facilitators related to technical aspects of processing HTA reports and to the contact and interaction between researchers and policymakers had the greatest importance in Colombia.

We report on miniaturized silicon field emitter arrays for the application in compact and energy-saving vacuum-microelectronic devices, e.g. sensors or x-ray tubes. Since standard silicon semiconductor technology has been used for the fabrication, they may be easily integrated with other silicon based circuits and devices on the same chip. The silicon tip geometry and the operating conditions were optimized in order to obtain highly uniform and stable electron field emission from large area cathode arrays. A series of uniform hexagonal tip arrays containing each 547 tips were fabricated and characterized. The electron emission properties of both individual tips as well as of complete emitter arrays were investigated. A saturation level in the voltage-current characteristics was found, which can be explained by the limitation of the supply of electrons due to the p-type silicon wafer material. When operating the arrays in the current saturation regime at an emission current of ~ 1 nA per tip, a highly stable and low noise emission can be observed.

We report on the simulation and fabrication of nanostructured silicon surfaces for field emission (FE) applications, e.g. ionization sensors and x-ray tubes. For the design and optimization of field-emitting silicon structures, the influence of the geometric parameters like tip height, apex radius, aperture angle and curvature shape on the field enhancement factor was investigated by simulation using finite element method. A universal geometric model which describes the real geometry of our silicon structures sufficiently accurate was taken for modeling a variety of different silicon tip structures as well as ridge structures. While a high dependency of the field enhancement on the aspect ratio and the aperture angle was found, the simulations show that the elliptic curvature affects the field enhancement only marginally. Finally, an improved process for fabrication of such silicon structures on n-type as well as p-type substrate is described, using reactive ion etching with adjustable anisotropy, wet thermal oxidation and wet etching.