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The Threshold Level Method is an approach that enables comparability across all hydrological levels. This advantage is used especially in studies on drought propagation. There are different calculation procedures for this method. The effect that the choice of a variable versus a constant threshold level method has on drought characteristics and drought propagation patterns has not been fully explored yet. Also, most drought propagation studies have analyzed modelled data, suggesting that applicability to observations be tested. We tested the Constant and the Variable Threshold Level Method for the 10th, 20th and 30th percentile on observed precipitation, streamflow, and groundwater data from Germany, and compared drought characteristics and drought propagation patterns by means of statistical analysis and synoptic assessment. The characteristic effects of choosing a variable versus a constant threshold are: (1) a substantial increase in short droughts, (2) a moderate decrease in intermediate droughts and (3) a minor increase in long droughts. Furthermore, in slow-reacting lowland catchments, theoretical propagation characteristics could mostly be confirmed. In faster-reacting upland catchments, this was not always the case and considerable differences arose. Sources of ambiguity were predominantly groundwater in lowlands and streamflow in the mountainous catchments. In conclusion, there is potential of diverging inference from the same data, depending on the chosen methodology.

Goldfish,Carassius auratus, were acclimated for 2 to 3.5 weeks to three temperature regimes: [1] temporally-constant (10, 20 and 30°C), [2] diurnally-cycling (20 ± 10°C) and [3] randomly-fluctuating (± 2°C at approximately 2h intervals between extremes of 10 and 30°C). No significant differences in hematocrit were evident. Hemoglobin levels in fish at constant 30°C and under randomly fluctuating temperature were significantly elevated. Of the three hemoglobin isomorphs observed, the two minor components (G1, G3) tended to decrease in relative abundance with increase in constant temperature, but increased under varying temperature regimes. The converse was true of the principal hemoglobin, G2. Extent of isomorph variation was correlated with extent of temperature variability. These observations confirm that temperature variability significantly effects thermoacclimatory response. The functional significance of changes in isomorph abundances during the acclimatory process is considered.

The present study compared neuromuscular fatigue of the knee extensor muscles following highly variable versus constant power output cycling. Ten subjects performed two 33-min cycling trials of the same average power output, in a random order. Cycling exercise was performed either at constant (CST) power output, corresponding to 70% of the maximal aerobic power (MAP), or at variable (VAR) power output with alternating high (200, 150 and 100% of MAP during 10, 15 and 20 s, respectively) and moderate (50% of MAP) power output periods. Neuromuscular tests were performed before and immediately after the two trials. Heart rate (HR) was measured during exercise and blood lactate concentration ([La]) at the end of both trials. Reductions in maximal voluntary contraction torque, voluntary activation level and peak doublet were significantly greater after VAR than after CST. HR and [La] were significantly higher during VAR than during CST. Cycling at a varying power output in comparison to constant power resulted in additional muscular fatigue that may be explained by greater anaerobic contribution and muscle solicitation during the highly variable power output protocol.

Purpose: To evaluate the effects of variable versus constant dose rate in volumetric modulated arc (VMAT) treatment planning for prostate cases. Method and Materials:A retrospective investigation on fifteen prostate cases was performed. Two dosimetrically identical linacs were commissioned in Pinnacle TPS. One machine was variable dose rate capable, while the other was constant dose rate capable for VMAT planning purposes. PTVs and OARs (rectum and bladder) were delineated for each case. Two VMAT plans were generated per case: each comprised of a single arc and comparing variable to constant dose rate. Both plans were normalized such that 95% of the PTV was covered by the same prescription dose. Plan quality was evaluated by several dose indices used as DVH objectives in the inverse optimization. In addition, dose inhomogeneity across the PTV was tallied together with MUs and estimated treatment times. Variable dose rare plans were used as reference. Results: The majority of rectum and bladder doses to 10%, 20%, and 40% of the OAR volumes differed by less than 3% between the two plans plans. Even for the cases with larger than 3% deviation the constant dose rate plans were clinically acceptable. Dose inhomogeneity across the PTV however was larger for constant dose rate plans, where for 80% of the cases it was over 3%, while it was within 3% for all variable dose rate cases. The MUs for the two delivering modes were comparable, while the treatment times differed three‐fold. Conclusions: The results indicate that variable and constant dose rate VMAT plans for prostate carcinoma result in comparable target coverage and OAR sparing. Nonetheless, the constant dose rate plans exhibit higher dose inhomogeneity across the target and the clinical applicability should be carefully evaluated for the potential hotspots in undesired location.