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To study the potential consequences of differences in the evaluation of variable versus uniform relative biological effectiveness calculations in proton radiotherapy for prostate cancer.Experimental data with proton beams suggest that relative biological effectiveness increases with linear energy transfer. This relation also depends on thePhenomenological models clearly predict higher relative biological effectiveness values compared to microdosimetric kinetic model, that seems to approach to the constant value of 1.1 adopted in the clinics, at least for low linear energy transfer values achieved in typical prostate proton plans. All models predict a higher increase of the relative biological effectiveness-weighted dose for the prostate tumor than for the rest of structures involved due to its lower

Recently, we have developed optimal harvesting policies based on profit optimization in random varying environments. Namely, we have considered a logistic stochastic differential equation growth model, with the purpose of discussing the use of variable versus constant effort harvesting policies in terms of the expected accumulated discounted profit during a finite time interval. Using realistic parameters, we have concluded that there is only a slight reduction in profit when choosing the applicable constant effort policy instead of the variable effort policy, which presents strong disadvantages. Here, we apply a logistic growth model and a more general profit structure to present alternative policies based on variable effort, named stepwise policies, where the harvesting effort is determined, under the optimal variable effort policy, at the beginning of each year (or of each biennium) but is kept constant during that year (biennium). Replacing the optimal variable effort policy by these stepwise non-optimal policies has the advantage of applicability but, at best, considerably reduces the already small profit advantage the optimal variable effort policy has over the optimal constant effort sustainable policy.

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.

This study analyses trends of mean (Tm), maximum (Tx), minimum (Tn), dew point (Td), and wet-bulb temperatures (Tw) on an annual, seasonal, and monthly time scale over Spain during the period 1981–2010. The main purpose was to determine how temperature and humidity changes are impacting on Tw, which is probably a better measure of climate change than temperature alone. In this study, 43 weather stations were used to detect data trends using the nonparametric Mann-Kendall test and the Sen method to estimate the slope of trends. Significant linear trends observed for Tm, Tx, and Tn versus year were 56, 58, and 47 % of the weather stations, respectively, with temperature ranges between 0.2 and 0.4 °C per decade. The months with bigger trends were April, May, June, and July with the highest trend for Tx. The spatial behaviour of Td and Tw was variable, with various locations showing trends from −0.6 to +0.3 °C per decade for Td and from −0.4 to +0.5 °C per decade for Tw. Both Td and Tw showed negative trends for July, August, September, November, and December. Comparing the trends versus time of each variable versus each of the other variables exhibited poor relationships, which means you cannot predict the trend of one variable from the trend of another variable. The trend of Tx was not related to the trend of Tn. The trends of Tx, Tm, and Tn versus time were unrelated to the trends versus time of either Td or Tw. The trend of Tw showed a high coefficient of determination with the trend of Td with an annual value of R2 = 0.86. Therefore, the Tw trend is more related to changes in humidity than temperature.

This chapter discusses local land and property taxes. There are two components to the property tax—the base and the rate. In most countries, the base is property value, but in some countries it is based on area. Regardless, the success of any assessment system depends on a number of critical components—property identification; assessment uniformity; assessment responsibility and frequency; an effective appeals mechanism; and making use of ever-improving mass assessment techniques. The tax rate is the second component. Local governments should be responsible for setting the local rate. Major issues include variable versus uniform tax rates; overtaxation of business properties; use of tax limits; property tax incentives; regressivity and tax relief; and treatment of special properties.

This study is aimed at analyzing the difference of using fixed weight aggregate inventory to sales ratios rather than “traditional”, that is, variable weighted, aggregated inventory to sales ratios. It shows that interpretations of these ratios may be problematic because different aggregation methods are signaling different time trends under certain circumstances. Analyzing the inventory performance of German corporations between 1993 and 2005, we find that the total inventory to sales ratio decreased in a statistically significant extent in the majority of industry sectors during the period investigated. Considering the effects of using fixed aggregation weights on our results, some changes concerning significance of results occur. The additional use of fixed aggregation weights is helpful because it isolates any trends observed in the aggregated inventory to sales ratio series to fluctuations in the underlying (sub) sectors’ inventory to sales ratio, not shifts in the composition of the aggregate.

Fixed-rate versions of rule-consequentialism and rule-utilitarianism evaluate rules in terms of the expected net value of one particular level of social acceptance, but one far enough below 100% social acceptance to make salient the complexities created by partial compliance. Variable-rate versions of rule-consequentialism and rule-utilitarianism instead evaluate rules in terms of their expected net value at all different levels of social acceptance. Brad Hooker has advocated a fixed-rate version. Michael Ridge has argued that the variable-rate version is better. The debate continues here. Of particular interest is the difference between the implications of Hooker's and Ridge's rules about doing good for others.

Stem-and-leaf displays have been widely taught since John W. Tukey publicized them energetically in the 1970s. They remain useful for many distributions of small or modest size, especially for showing fine structure such as digit preference. Stata's implementation stem produces typed text displays and has some inevitable limitations, especially for comparison of two or more displays. One can re-create stem-and-leaf displays with a few basic Stata commands as scatterplots of stem variable versus position on line with leaves shown as marker labels. Comparison of displays then becomes easy and natural using scatter, by(). Back-to-back presentation of paired displays is also possible. I discuss variants on standard stem-and-leaf displays in which each distinct value is a stem, each distinct value is its own leaf, or axes are swapped. The problem shows how one can, with a few lines of Stata, often produce standard graph forms from first principles, allowing in turn new variants. I also present a new program, stemplot, as a convenience tool.

SUMMARYCertain tiger moths (Arctiidae) defend themselves against bats by phonoresponding to their echolocation calls with trains of ultrasonic clicks. The dogbane tiger moth, Cycnia tenera, preferentially phonoresponds to the calls produced by attacking versus searching bats, suggesting that it either recognizes some acoustic feature of this phase of the bat's echolocation calls or that it simply reacts to their increased power as the bat closes. Here, we used a habituation/generalization paradigm to demonstrate that C. tenera responds neither to the shift in echolocation call frequencies nor to the change in pulse duration that is exhibited during the bat's attack phase unless these changes are accompanied by either an increase in duty cycle or a decrease in pulse period. To separate these features, we measured the moth's phonoresponse thresholds to pulsed stimuli with variable versus constant duty cycles and demonstrate that C. tenerais most sensitive to echolocation call periods expressed by an attacking bat. We suggest that, under natural conditions, C. tenera identifies an attacking bat by recognizing the pulse period of its echolocation calls but that this feature recognition is influenced by acoustic power and can be overridden by unnaturally intense sounds.

Swain (1997) employed the mathematical model of Di Prampero et al. (1979) to predict that, for cycling time-trials, the optimal pacing strategy is to vary power in parallel with the changes experienced in gradient and wind speed. We used a more up-to-date mathematical model with validated coefficients (Martin et al., 1998) to quantify the time savings that would result from such optimization of pacing strategy. A hypothetical cyclist (mass = 70 kg) and bicycle (mass = 10 kg) were studied under varying hypothetical wind velocities (-10 to 10 m x s(-1)), gradients (-10 to 10%), and pacing strategies. Mean rider power outputs of 164, 289, and 394 W were chosen to mirror baseline performances studied previously. The three race scenarios were: (i) a 10-km time-trial with alternating 1-km sections of 10% and -10% gradient; (ii) a 40-km time-trial with alternating 5-km sections of 4.4 and -4.4 m x s(-1) wind (Swain, 1997); and (iii) the 40-km time-trial delimited by Jeukendrup and Martin (2001). Varying a mean power of 289 W by +/- 10% during Swain's (1997) hilly and windy courses resulted in time savings of 126 and 51 s, respectively. Time savings for most race scenarios were greater than those suggested by Swain (1997). For a mean power of 289 W over the "standard" 40-km time-trial, a time saving of 26 s was observed with a power variability of 10%. The largest time savings were found for the hypothetical riders with the lowest mean power output who could vary power to the greatest extent. Our findings confirm that time savings are possible in cycling time-trials if the rider varies power in parallel with hill gradient and wind direction. With a more recent mathematical model, we found slightly greater time savings than those reported by Swain (1997). These time savings compared favourably with the predicted benefits of interventions such as altitude training or ingestion of carbohydrate-electrolyte drinks. Nevertheless, the extent to which such power output variations can be tolerated by a cyclist during a time-trial is still unclear.

The role of the equation of state for a perfectly conducting, relativistic magnetized fluid is the main subject of this work. The ideal constant $\Gamma$-law equation of state, commonly adopted in a wide range of astrophysical applications, is compared with a more realistic equation of state that better approximates the single-specie relativistic gas. The paper focus on three different topics. First, the influence of a more realistic equation of state on the propagation of fast magneto-sonic shocks is investigated. This calls into question the validity of the constant $\Gamma$-law equation of state in problems where the temperature of the gas substantially changes across hydromagnetic waves. Second, we present a new inversion scheme to recover primitive variables (such as rest-mass density and pressure) from conservative ones that allows for a general equation of state and avoids catastrophic numerical cancellations in the non-relativistic and ultrarelativistic limits. Finally, selected numerical tests of astrophysical relevance (including magnetized accretion flows around Kerr black holes) are compared using different equations of state. Our main conclusion is that the choice of a realistic equation of state can considerably bear upon the solution when transitions from cold to hot gas (or viceversa) are present. Under these circumstances, a polytropic equation of state can significantly endanger the solution., Comment: 14 pages, 14 figures

International audience; The aim of this study was to investigate the metabolic responses to variable versus constant-intensity (CI) during 20-km cycling on subsequent 5-km running performance. Ten triathletes, not only completed one incremental cycling test to determine maximal oxygen uptake and maximal aerobic power (MAP), but also three various cycle-run (C–R) combinations conducted in outdoor conditions. During the C–R sessions, subjects performed first a 20-km cycletime trial with a freely chosen intensity (FCI, ~80% MAP) followed by a 5-km run performance. Subsequently, triathletes were required to perform in a random order, two C–R sessions including either a CI, corresponding to the mean power of FCI ride, or a variable-intensity (VI) during cycling with power changes ranging from 68 to 92% MAP, followed immediately by a 5-km run. Metabolic responses and performances were measured during the C–R sessions. Running performance was significantly improved after CI ride (1118 ± 72 s) compared to those after FCI ride (1134 ± 64 s) or VI ride (1168 ± 73 s) despite similar metabolic responses and performances reported during the three cycling bouts. Moreover, metabolic variables were not significantly different between the run sessions in our triathletes. Given the lack of significant differences in metabolic responses between the C–R sessions, the improvement in running time after FCI and CI rides compared to VI ride suggests that other mechanisms, such as changes in neuromuscular activity of peripheral skeletal muscle or muscle fatigue, probably contribute to the influence of power output variation on subsequent running performance.

This paper measures the pass-through of trade costs into U.S. import prices by using actual data on duties/tariffs and freight-related costs. The key innovation is to decompose the indirect effects of trade costs (on prices) into the effects on markups, quality and productivity while measuring/interpreting the pass-through of trade costs into welfare. Robust to the consideration of variable versus constant markups, there is evidence for incomplete pass-through, mostly due to the negative indirect effects of trade costs on marginal costs, suggesting that lower trade costs are associated with imports that have higher marginal costs; markups are affected relatively less. When the effects of trade costs on marginal costs are further decomposed into their components, the positive contribution of quality dominates in all cases, followed by the negative effects of productivity, suggesting that lower trade costs are associated with higher-quality imports that have been produced with lower productivity.

In this paper we study optimal harvesting of the Norwegian spring-spawning herring stock. The biological model is described by a discrete time age-structured model. The optimal harvesting patterns are studied numerically and the results show that when using a linear cost function and constant price in the optimisation model, the optimal harvesting pattern is pulse fishing. However, optimal constant fishing effort gives only slightly lower profit. Moreover, when price is made responsive to harvest the optimal harvesting strategy is substantially smoothed.

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.

Aneurysms are an enlargement of a blood vessel due to a weakened wall and can pose significant health risks. Abdominal aortic aneurysms alone are the 13th leading cause of death in the United States, with 15,000 deaths annually. While there are recommended guidelines for doctors to follow in the treatment of specific aneurysms, they cannot guarantee a satisfactory outcome. Computer simulations of an aneurysm may be able to help doctors in their treatment; however, the results are inaccurate if the vessel wall thickness is poorly measured. In order to provide more accurate, patient-specific simulations, not only does geometry for the fluid domain need to be created from medical images for analysis, but the creation of more accurate models for the wall needs to be accomplished as well. This paper proposes a solution to the latter by deforming the mesh from a healthy vessel into one with an aneurysm through parameterization and the use of a spring model. The thickness of the resulting wall model is empirically valid and fluid-structure interaction simulations show significant improvements when using a variable versus a uniform wall thickness.

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.

For networks with large scale integration of wind farms this paper demonstrates a significant difference between the transient behavior of variable speed wind systems that adopt doubly fed induction generators with a four quadrant ac-to-ac converter connected to the rotor windings (DFIG) and a fixed speed wind system, where the conventional cage induction generator is used. The reason for this difference is explained, and it is shown that the phenomenon is due to the ability of the two dedicated rotor current regulators of the DFIG to control the electrical torque and reactive power quickly and accurately. This difference is clearly observed after a severe fault (short circuit) occurrence. It will be demonstrated that the adjustable speed generator (DFIG) enhances system stability in power networks.

Deals with spatio-temporal analysis of propagation rays received on an array before, within and after the first convergence area in Central Atlantic. The modelisation of this situation shows that the temporal distribution of the energetic arrivals is rapidly variable versus propagation distance and depth. In order to characterize accurately this phenomenon, a specific experimentation has been organized off the Azores by the French Navy, whose received data are very interesting for those conditions of propagation. After propagation, the transmitted signal is received on an array of fixed hydrophones and also upon a vertically moving hydrophone. Identification of the several paths is thus possible. Thanks to high resolution spatio-temporal methods such as Wide-Band Active Music, it is possible to define precisely the spatio-temporal response of the medium inside this area of propagation characterized by the presence of caustics. In the first part of the paper, the authors describe the experimentation and the method. Then, experimental results are compared with predictions given either by ray-tracing modelisation and normal modes analysis.

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.

Specificity designs in psychopathology research are used to examine whether a variable is unique to a given disorder. When nonspecificity is observed, it typically is assumed that the variable in question is not a cause of the disorder, but is instead a nonspecific consequence of general psychopathology. Such reasoning is flawed, however, because it fails to distinguish between testing a particular causal model containing the variable versus testing the causal status of the particular variable within the model. A variable may be nonspecific, but still causal, if it is one of several multiple interacting causes or if a nosological error has been made. A recognition of these complexities has implications for the nature of the psychopathology control group selected.

The assumption of stable beta coefficient within the context of the market model, and the consequent use of ordinary least squares. estimation, has been widely criticized. In this study an alternative market model is offered in which beta is allowed to vary over time. Varying parameters regression is used to estimate the variable beta and the estimates are compared to those produced by ordinary least squares in terms of accuracy of predictions. The results indicate that neither model shows a clear advantage over the other. Even when a large change in beta was simulated, the differences in prediction errors were rather small though slightly in favor of the varying parameters model.

In a recent article in this journal, Stutzer (1984) investigated the relative in-efficiencies of fixed versus variable rate subsidies as they pertain to analyzing different forms of revenue sharing. His analysis butlds on the theoretical presumption that a variable rate subsidy is generally less inefficient than a fixed rate subsidy of equal size. In this article it is shown that if the good being subsidized is a public good, it is possible that a fixed rate subsidy will be more efficient than a variable rate subsidy from a benefit-cost analysis perspective, once collective decision-making aspects are incorporated into the analysis. This indicates the importance of incorporating the presence of public goods, when appropriate, into an efficiency analysis to see whether traditional results are still valid.

The effects of exposure pattern on the toxicity of acetaldehyde vapour were investigated in 4-week inhalation studies. Male rats were exposed to 500 or 150 and 110 ppm for 6 h per day/5 days per week. One group of animals was exposed without interruption, the exposure of a second group was interrupted for 1.5 h between the first and second 3-h periods, the exposure of a third group was similarly interrupted and for six 5 min periods exposure was increased sixfold. Peak exposures of up to 3000 ppm superimposed on 500 ppm acetaldehyde caused irritation and excitation, and reduced body weight gain. No such effects occurred after interrupted or uninterrupted exposure to 500 ppm acetaldehyde without peak loads. A reduced phagocytotic index of lung macrophages was found in each of the groups exposed to 500 ppm acetaldehyde, the effect being most marked in the group with superimposed peaks of 3000 ppm. Degeneration of the nasal olfactory epithelium was observed in rats uninterruptedly exposed to 500 ppm acetaldehyde. Interruption of the exposure or interruption combined with peak exposure did not visibly influence this adverse effect on the nose. No compound-related effects were seen in rats interruptedly or uninterruptedly exposed to 150 ppm acetaldehyde or interruptedly exposed to 110 ppm with peak loads of 660 ppm. As a consequence 150 ppm acetaldehyde can be considered a 'no-toxic-effect level' in male rats exposed for 6 h/day, 5 days/week, during a 4-week period. It was concluded that the interruption of daily exposure by 1.5 h exposure-free period or by the superimposition of six times 5 min peak exposure periods did not appreciably influence the nasocytotoxic potency of acetaldehyde. Furthermore for inhalation toxicity testing of irritants such as acetaldehyde the use of variable exposure patterns does not seem to produce more relevant toxicity data than the use of uninterrupted daily exposure to a fixed concentration. Chemicals/CAS: acetaldehyde, 75-07-0; Acetaldehyde, 75-07-0

The economic implications of variable grazing fees and single grazing fees on Federal lands are important considerations relative to further policy changes. Many factors must be considered when establishing fees on different grazing units. Quantity and quality of forage are only two of these factors and generally not the most important ones. Variable grazing fees will have to be implemented if the government is going to minimize the problem of having some of its land over-priced and some under-priced.