Reactive security monitoring, self-driving cars, the Internet of Things (IoT), and many other novel applications require systems for both writing events arriving at very high and fluctuating rates to persistent storage as well as supporting analytical ad hoc queries. As standard database systems are not capable of delivering the required write performance, log-based systems, key-value stores, and other write-optimized data stores have emerged recently. However, the drawbacks of these systems are a fair query performance and the lack of suitable instant recovery mechanisms in case of system failures.
In this article, we present ChronicleDB, a novel database system with a storage layout tailored for high write performance under fluctuating data rates and powerful indexing capabilities to support a variety of queries. In addition, ChronicleDB offers low-cost fault tolerance and instant recovery within milliseconds. Unlike previous work, ChronicleDB is designed either as a serverless library to be tightly integrated in an application or as a standalone database server. Our results of an experimental evaluation with real and synthetic data reveal that ChronicleDB clearly outperforms competing systems with respect to both write and query performance.
We demonstrate sub-100 ps pulses with a Yb 3+ :YAG microchip laser passively Q-switched by a Cr 4+ :YAG saturable absorber. By introducing a subcavity, the laser threshold and the saturation energy are decreased which helps to prevent damage and to vary the effective emission and absorption cross sections. Pulse widths of 84 ps, repetition rates of 3.3 kHz and pulse energies of 32 µJ are achieved. This allows direct micromaterial processing e.g. for ophthalmic surgeries. To the best of our knowledge, this is the first sub-100 ps Yb 3+ :YAG/Cr 4+ :YAG microchip laser. A new approximation is used to calculate the rate equations for multiple longitudinal modes and to determine the threshold for single-longitudinal-mode operation.
The laser systems currently used in ophthalmology either have some pulse length dependent side effects or are very expensive due to their complexity. Therefore, a newly developed approach using picosecond laser sources is investigated. These lasers combine the advantages of the low price of currently used short-pulse laser sources with the cold material ablation possibilities of high-end femtosecond sources. The surgeries intended are laser iridotomy, capsulotomy/post-cataract treatment and selective laser-trabeculoplasty (SLT). They are demonstrated on post mortem porcine eyes. The result is a more precise, less frayed tissue ablation with picosecond pulses in comparison to nanosecond pulses. The pulse energy could be reduced to (50 20) µJ per pulse instead of 1mJ to 10mJ per pulse, which is currently applied. The study of shock waves and cavitation bubbles revealed a huge difference in pressure between picosecond pulses (0:25MPa at 50 µJ) and nanosecond pulses (37MPa at 5 mJ). Therefore, the risk of collateral damage leading to potential additional clinical patterns and adverse effects could be significantly reduced.
Medical and nursing shortages in rural areas represent a current serious public health problem. The healthcare of the rural population is at risk. This study compares perceived workload, job satisfaction and work-life balance of physicians and nurses at a clinic in a rural area with two clinics of a University hospital. Physicians and nurses were interviewed anonymously with a standardized questionnaire (paper and pencil), including questions on job satisfaction, subjective workload and work-life balance. The response rate was almost 50% in the University hospital as well as in the municipal hospital. 32 physicians and 54 nurses from the University hospital and 18 physicians and 137 nurses from the municipal hospital participated in the survey. Nurses at the University hospital assessed the organization of the daily routine with 94.1% as better than those at the municipal hospital (82.4%, p=0.03). Physicians at the University hospital were able to better implement acquired knowledge at a University clinic with 87.5% than their counterparts at the municipal hospital (55.5%, p=0.02). In contrast to their colleagues at the municipal hospital, only 50% of the physicians at the University hospital subjectively considered their workload as just right (83.3% municipal, p=0.02). 96.9% of the physicians at the University hospital were "daily" or "several times a week" under time pressure (municipal 50%, p<0.01). Nurses of both hospitals had sufficient opportunity to reconcile work and family life (62.9% University hospital, 72.8% Municipal hospital). In contrast, only 20% of the physicians at the University Hospital but 42.9% of the physicians of the municipal hospital had sufficient opportunities to balance workload and family (p=0.13). The return rate of almost 50% can be described as good. Due to the small number of physicians, especially from the municipal hospital, it can be assumed that some interesting differences could not be detected. There were only slight differences between the nurses from the two hospitals. In contrast, subjective workload and stress factors reported by physicians at the University Hospital were significantly higher than those by doctors at the municipal hospital.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.