A Common-Path Interferometer for Time-Resolved and Shot-Noise-Limited Detection of Single Nanoparticles

We give a detailed description of a novel method for time-resolved experiments on single non-luminescent nanoparticles. The method is based on the combination of pump-probe spectroscopy and a common-path interferometer. In our interferometer, probe and reference arms are separated in time and polarization by a birefringent crystal. The interferometer, fully described by an analytical model, allows us to separately detect the real and imaginary contributions to the signal. We demonstrate the possibilities of the setup by time-resolved detection of single gold nanoparticles as small as 10 nm in diameter, and of acoustic oscillations of particles larger than 40 nm in diameter

Control system for a superconducting rectifier using a microcomputer

Within the scope of a research program of superconducting rectifiers software is being developed to take care of the control of such systems. The hard-ware architecture which interferes with the in and output signals is based on a LSI-11/2 microprocessor with sufficient mass storage for data logging, console and printer. The flexibility inherent to this hardware configuration is desired for optimalisation of the rectifier concerning maximum current, power, efficiency and quench stability. The paper describes the structure of the program and the interaction between both computer hardware and software and the superconducting rectifier. However, because the reliability of computersystems is unsatisfactory an additional hardware protection system still handles the most important alarms

Lessons Learned from a Full-Scale Dyke Failure Test

A full-scale failure test has been performed on an old river dyke in the Netherlands, to determine its actual strength against failure due to the uplift mechanism and to validate the Van model for the stability analysis of dykes prone to uplift induced failure. The test has been a success and clearly showed the relevance and significance of the uplift mechanism. In combination with earlier verifications, the Van model was found to be suitable, which has already lead to significant reductions on dyke reinforcement projects. The large gap between the actual strength and the calculated strength was confirmed. This gap appeared to be partly necessary because of the large variation in the results of dyke stability analyses by different geotechnical consultants. For the near future, the test may serve as an important benchmark for the development of a more rationally based safety philosophy

Horizontal Translational Failures of Levees Due to Water Filled Gaps

A peat levee at Wilnis in The Netherlands suddenly failed at the end of the relatively dry summer of 2003. On Monday, 29 August 2005, Hurricane Katrina struck the U.S. gulf coast and breached, among other failures, the 17th Street Canal. These failures triggered large research programs. In the Wilnis case, it was eventually deduced that the 5-m horizontal translation of the levee was triggered by a combination of reduced weight by evaporation, shrinkage and cracking of the peat material, and an increased head in the sand layer under the dike. A key factor in the 17th Street Canal failure was the formation of a gap between the wall and the levee fill on the canal side of the fill. Due to climate change, more extreme dry and wet periods, land subsidence, and increasing sea and river levels, the horizontal shifting due to cracking is becoming more significant in the safety assessments of levees. In this paper, aspects of horizontal failures during extreme dry or wet periods are elaborated. First, a geo-hydrologic design procedure to assess the consequences of droughts for cracked peat levees is presented. The design procedure is then validated with measurements of a peat levee, the Middelburgsekade, and extreme water table positions that are likely to occur once in a period of 400 years that have been predicted for this levee. Furthermore, the most dangerous cracks for the Wilnis case are indicated. Next, the performance of levees and floodwalls during Hurricane Katrina are presented. Finally, the failure of the 17th Street Canal breach in New Orleans is described in detail. Conclusions are drawn related to horizontal failures and location of cracks during extreme weather condition

Extending the bandwidth of optical-tweezers interferometry

The extension of the bandwidth of optical-tweezers interferometry was discussed. It was found that the detection bandwidth was extended to at least 100 KHz, either by using wavelengths below 850 nm or by using different detectors at longer wavelengths. The power spectral density of the Brownian motion of micron-sized beads in optical tweezers was also measured

A Bodyweight-Dependent Allometric Exponent for Scaling Clearance Across the Human Life-Span

Purpose: To explore different allometric equations for scaling clearance across the human life-span using propofol as a model drug. Methods: Data from seven previously published propofol studies ((pre)term neonates, infants, toddlers, children, adolescents and adults) were analysed using NONMEM VI. To scale clearance, a bodyweight-based exponential equation with four different structures for the exponent was used: (I) 3/4 allometric scaling model; (II) mixture model; (III) bodyweight-cut-point separated model; (IV) bodyweight-dependent exponent model. Results: Model I adequately described clearance in adults and older children, but overestimated clearance of neonates and underestimated clearance of infants. Use of two different exponents in Model II and Model III showed significantly improved performance, but yielded ambiguities on the boundaries of the two subpopulations. This discontinuity was overcome in Model IV, in which the exponent changed sigmoidally from 1.35 at a hypothetical bodyweight of 0 kg to a value of 0.56 from 10 kg onwards, thereby describing clearance of all individuals best. Conclusions: A model was developed for scaling clearance over the entire human life-span with a single continuous equation, in which the exponent of the bodyweight-based exponential equation varied with bodyweight

Development and external validation study combining existing models and recent data into an up-to-date prediction model for evaluating kidneys from older deceased donors for transplantation

With a rising demand for kidney transplantation, reliable pre-transplant assessment of organ quality becomes top priority. In clinical practice, physicians are regularly in doubt whether suboptimal kidney offers from older donors should be accepted. Here, we externally validate existing prediction models in a European population of older deceased donors, and subsequently developed and externally validated an adverse outcome prediction tool. Recipients of kidney grafts from deceased donors 50 years of age and older were included from the Netherlands Organ Transplant Registry (NOTR) and United States organ transplant registry from 2006-2018. The predicted adverse outcome was a composite of graft failure, death or chronic kidney disease stage 4 plus within one year after transplantation, modelled using logistic regression. Discrimination and calibration were assessed in internal, temporal and external validation. Seven existing models were validated with the same cohorts. The NOTR development cohort contained 2510 patients and 823 events. The temporal validation within NOTR had 837 patients and the external validation used 31987 patients in the United States organ transplant registry. Discrimination of our full adverse outcome model was moderate in external validation (C-statistic 0.63), though somewhat better than discrimination of the seven existing prediction models (average C-statistic 0.57). The model's calibration was highly accurate. Thus, since existing adverse outcome kidney graft survival models performed poorly in a population of older deceased donors, novel models were developed and externally validated, with maximum achievable performance in a population of older deceased kidney donors. These models could assist transplant clinicians in deciding whether to accept a kidney from an older donor