Babinec T.M.,Harvard University |
Choy J.T.,Harvard University |
Smith K.J.M.,Harvard University |
Smith K.J.M.,Vrije University |
And 2 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2011
We present the design and fabrication of nanobeam photonic crystal cavities in single crystal diamond for applications in cavity quantum electrodynamics. First, we describe three-dimensional finite-difference time-domain simulations of a high quality factor (Q∼ 106) and small mode volume [V∼0.5 (λ/n) 3] cavity whose resonance corresponds to the zero-phonon transition (637 nm) of the nitrogen-vacancy color center in diamond. This high Q/V structure, which would allow for strong light-matter interaction, is achieved by gradually tapering the size of the photonic crystal holes between the defect center and the mirror regions of the nanobeam. Next, we demonstrate two different focused ion beam (FIB) fabrication strategies to generate thin diamond membranes and nanobeam photonic crystal resonators from a bulk crystal. These approaches include a diamond crystal "side- milling" procedure as well as an application of the "lift-out" technique used in transmission electron microscopy sample preparation. Finally, we discuss certain aspects of the FIB fabrication routine that are a challenge to the realization of the high Q/V designs. © 2011 American Vacuum Society.
Bogerd N.,Empa - Swiss Federal Laboratories for Materials Science and Technology |
Perret C.,Institute for Clinical Research |
Bogerd C.P.,Empa - Swiss Federal Laboratories for Materials Science and Technology |
Rossi R.M.,Empa - Swiss Federal Laboratories for Materials Science and Technology |
And 2 more authors.
Journal of Sports Sciences | Year: 2010
Although pre-cooling is known to enhance exercise performance, the optimal cooling intensity is unknown. We hypothesized that mild cooling opposed to strong cooling circumvents skin vasoconstriction and thermogenesis, and thus improves cooling efficiency reflected in improved time to exhaustion. Eight males undertook three randomized trials, consisting of a pre-cooling and an exercise session. During the pre-cooling, performed in a room of 24.6±0.4°C and 24±6% relative humidity, participants received either 45 min of mild cooling using an evaporative cooling shirt or strong cooling using an ice-vest. A no-cooling condition was added as a control. Subsequent cycling exercise was performed at 65% VO2peak in a climatic chamber of 29.3±0.2°C and 80±3% relative humidity. During the pre-cooling session, mild and strong cooling decreased the skin blood flow compared with the control. However, no differences were observed between mild and strong cooling. No thermogenesis was observed in any conditions investigated. The reduction of body heat content after pre-cooling was two times larger with strong cooling (39.5±8.4 W · m-2) than mild cooling (21.2±5.1 W · m-2). This resulted in the greatest improvement in time to exhaustion with strong cooling. We conclude that the cooling intensities investigated had a similar effect on cooling efficiency (vasoconstriction and thermogenesis) and that the improved performance after strong cooling is attributable to the greater decrease in body heat content. © 2010 Taylor & Francis.
Nordin S.,Linkoping University |
Carlbring P.,Umea University |
Cuijpers P.,Vrije University |
Andersson G.,Karolinska Institutet
Behavior Therapy | Year: 2010
Cognitive behavioral bibliotherapy for panic disorder has been found to be less effective without therapist support. In this study, participants were randomized to either unassisted bibliotherapy (n=20) with a scheduled follow-up telephone interview or to a waiting list control group (n=19). Following a structured psychiatric interview, participants in the treatment group were sent a self-help book consisting of 10 chapters based on cognitive behavioral strategies for the treatment of panic disorder. No therapist contact of any kind was provided during the treatment phase, which lasted for 10 weeks. Results showed that the treatment group had, in comparison to the control group, improved on all outcome measures at posttreatment and at 3-month follow-up. The tentative conclusion drawn from these results is that pure bibliotherapy with a clear deadline can be effective for people suffering from panic disorder with or without agoraphobia. © 2010.
De vries O.J.,VU University Amsterdam |
Peeters G.,University of Queensland |
Elders P.,VU University Amsterdam |
Sonnenberg C.,Old Age Psychiatry |
And 3 more authors.
Age and Ageing | Year: 2013
Background: the STOPP criteria advise against the use of long-acting benzodiazepines (LBs). Objective: to study whether LBs are associated with a higher fall risk than short-acting benzodiazepines (SBs) (elimination half-life ≤10 h). Methods: we used base-line data and prospective fall follow-up from the Longitudinal Aging Study Amsterdam, a longitudinal cohort study including 1,509 community-dwelling older persons (Study 1) and from a separate fall prevention study with 564 older persons after a fall (Study 2). Time to the first fall after inclusion and number of falls in the first year after inclusion were the primary endpoints. Results: both in Study 1 and Study 2 the use of SBs was associated with time to the first fall, hazard ratio (HR) 1.62 (95% CI: 1.03-2.56) and HR 1.64 (95% CI: 1.19-2.26),respectively. LBs were not significantly associated with time to first fall, HR 1.40 (0.85-2.31) and HR 1.08 (0.72-1.62). In both studies, the use of SBs was also associated with number of falls, odds ratio (OR) 1.28 (95% CI: 1.01-1.61) and OR 1.37 (95% CI: 1.10-1.70). LBs were not significantly associated with number of falls, OR 1.23 (0.96-1.57) and 1.10 (0.82-1.48). Conclusions: the use of SBs is not associated with a lower fall risk compared with LBs. The use of both SBs and LBs by old persons should be strongly discouraged. © The Author 2013. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved.
Jager T.,Vrije University |
Philosophical Transactions of the Royal Society B: Biological Sciences | Year: 2010
The interest of environmental management is in the long-term health of populations and ecosystems. However, toxicity is usually assessed in short-term experiments with individuals. Modelling based on dynamic energy budget (DEB) theory aids the extraction of mechanistic information from the data, which in turn supports educated extrapolation to the population level. To illustrate the use of DEB models in this extrapolation, we analyse a dataset for life cycle toxicity of copper in the earthworm Dendrobaena octaedra. We compare four approaches for the analysis of the toxicity data: No model, a simple DEB model without reserves and maturation (the Kooijman-Metz formulation), a more complex one with static reserves and simplified maturation (as used in the DEBtox software) and a full-scale DEB model (DEB3) with explicit calculation of reserves and maturation. For the population prediction, we compare two simple demographic approaches (discrete time matrix model and continuous time Euler-Lotka equation). In our case, the difference between DEB approaches and population models turned out to be small. However, differences between DEB models increased when extrapolating to more field-relevant conditions. The DEB3 model allows for a completely consistent assessment of toxic effects and therefore greater confidence in extrapolating, but poses greater demands on the available data. © 2010 The Royal Society.