Density functionals with asymptotic-potential corrections are required for the simulation of spectroscopic properties of materials

Five effects of correction of the asymptotic potential error in density functionals are identified that significantly improve calculated properties of molecular excited states involving charge-transfer character. Newly developed materials-science computational...

Concurrent Validity of Power From Three On-Water Rowing Instrumentation Systems and a Concept2 Ergometer

Purpose: Instrumentation systems are increasingly used in rowing to measure training intensity and performance but have not been validated for measures of power. In this study, the concurrent validity of Peach PowerLine (six units), Nielsen-Kellerman EmPower (five units), Weba OarPowerMeter (three units), Concept2 model D ergometer (one unit), and a custom-built reference instrumentation system (Reference System; one unit) were investigated.Methods: Eight female and seven male rowers [age, 21 ± 2.5 years; rowing experience, 7.1 ± 2.6 years, mean ± standard deviation (SD)] performed a 30-s maximal test and a 7 × 4-min incremental test once per week for 5 weeks. Power per stroke was extracted concurrently from the Reference System (via chain force and velocity), the Concept2 itself, Weba (oar shaft-based), and either Peach or EmPower (oarlock-based). Differences from the Reference System in the mean (representing potential error) and the stroke-to-stroke variability (represented by its SD) of power per stroke for each stage and device, and between-unit differences, were estimated using general linear mixed modeling and interpreted using rejection of non-substantial and substantial hypotheses.Results: Potential error in mean power was decisively substantial for all devices (Concept2, –11 to –15%; Peach, −7.9 to −17%; EmPower, −32 to −48%; and Weba, −7.9 to −16%). Between-unit differences (as SD) in mean power lacked statistical precision but were substantial and consistent across stages (Peach, ∼5%; EmPower, ∼7%; and Weba, ∼2%). Most differences from the Reference System in stroke-to-stroke variability of power were possibly or likely trivial or small for Peach (−3.0 to −16%), and likely or decisively substantial for EmPower (9.7–57%), and mostly decisively substantial for Weba (61–139%) and the Concept2 (−28 to 177%).Conclusion: Potential negative error in mean power was evident for all devices and units, particularly EmPower. Stroke-to-stroke variation in power showed a lack of measurement sensitivity (apparent smoothing) that was minor for Peach but larger for the Concept2, whereas EmPower and Weba added random error. Peach is therefore recommended for measurement of mean and stroke power.

Accuracy And Efficiency Of Digital Implant Planning And Guided Implant Surgery

Advances in digital technologies offer 3D integrated solutions for digital implnat planning.Virtual implant placement and guided implant surgery are claimed to provide more predictable results even in complicated implant treatments.Technology is now capable to properly transfer the virtually planned optimal positon of implants to reality during surgery.However clinicians have to be aware of the potential deviation factors and risks of the different types of guided surgery systems to reduce the risk of complications.The aim of this review is to evaluate the efficiency and accuracy of different computer-assisted dental implant placement techniques and to discuss potential error sources for each technique.

Qualitative and quantitative methods show stability in patterns of Cepaea nemoralis shell polymorphism in the Pyrenees over five decades

One of the emerging strengths of working with the land snail genus Cepaea is that historical collections can be compared against modern day samples, for instance to understand the impact of changing climate and habitat upon shell morph frequencies. However, one potential limitation is that prior studies scored shell ground colour by eye, usually in the field, into three discrete colours yellow, pink or brown. This incurs both potential error and bias in comparative surveys. In this study, we therefore aimed to use a quantitative method to score shell colour, and evaluated it by comparing patterns of C. nemoralis shell colour polymorphism, using both methods on present day samples, and against historical data gathered in the 1960s using the traditional method. The Central Pyrenees were used as an exemplar, because previous intensive surveys sometimes showed sharp discontinuities of morph frequencies within and between valleys. Moreover, selective factors, such as climate or the human impact in the Pyrenees, have significantly changed since 1960s. The main finding was that while quantitative measures of shell colour reduced the possibility of error, and standardised the procedure, the same altitudinal trends were recovered, irrespective of the method. There was remarkable stability in the local shell patterns over five decades, with the exception of one valley that has been subject to increased human activity. Therefore, although subject to potential error, human-scoring of snail colour data remains valuable, especially if persons have appropriate training. In comparison, while there are benefits in taking quantitative measures of colour in the laboratory, there are also several practical disadvantages, mainly in terms of throughput and accessibility. In the future, we anticipate that both methods may be combined, for example, using automated measures of colour taken from photos generated by citizen scientists conducting field surveys.

Technical note: CO₂ is not like CH₄ – limits of and corrections to the headspace method to analyse <i>p</i>CO₂ in water

Headspace analysis of CO2 frequently has been used to quantify the concentration of CO2 in freshwater. According to basic chemical theory, not considering chemical equilibration of the carbonate system in the sample vials will result in a systematic error. In this paper we provide a method to quantify the potential error resulting from simple application of Henry's law to headspace CO2 samples. By analysing the potential error for different types of water and experimental conditions we conclude that the error incurred by headspace analysis of CO2 is less than 5 % for samples with pH

Spatial Limit of CFD Model at Nanometer Scale Geometry: Part I: Capillary Flow

Numerical simulation using computational fluid dynamics has been studied broadly in various fields of applications. Along with the advancement in new technology especially those employing micro or nanoscale geometries or lab-on-chip devices, it is important to understand the efficiency of such numerical models at small geometrical scales. To access any potential error in numerical simulation using CFD, in the present work we report the investigation of capillary driven passive flow inside a channel of varying geometry. The potential error in the results of simulation at a very small scale is accessed by comparing it with the results of theoretical analysis. Hence, establishes a spatial limit of the continuum model for simulation in related applications. This gives new insight to the further study on CFD at nanometers scale geometry.

MWA tied-array processing III: Microsecond time resolution via a polyphase synthesis filter

A new high time resolution observing mode for the Murchison Widefield Array (MWA) is described, enabling full polarimetric observations with up to $30.72\,$ MHz of bandwidth and a time resolution of ${\sim}$ $0.8\,\upmu$ s. This mode makes use of a polyphase synthesis filter to ‘undo’ the polyphase analysis filter stage of the standard MWA’s Voltage Capture System observing mode. Sources of potential error in the reconstruction of the high time resolution data are identified and quantified, with the $S/N$ loss induced by the back-to-back system not exceeding $-0.65\,$ dB for typical noise-dominated samples. The system is further verified by observing three pulsars with known structure on microsecond timescales.

Detection of potential look-alike/sound-alike medication errors using Veterans Affairs administrative databases

Purpose Results of a study to estimate the prevalence of look-alike/sound-alike (LASA) medication errors through analysis of Veterans Affairs (VA) administrative data are reported. Methods Veterans with at least 2 filled prescriptions for 1 medication in 20 LASA drug pairs during the period April 2014–March 2015 and no history of use of both medications in the preceding 6 months were identified. First occurrences of potential LASA errors were identified by analyzing dispensing patterns and documented diagnoses. For 7 LASA drug pairs, potential errors were evaluated via chart review to determine if an actual error occurred. Results Among LASA drug pairs with overlapping indications, the pairs associated with the highest potential-error rates, by percentage of treated patients, were tamsulosin and terazosin (3.05%), glipizide and glyburide (2.91%), extended- and sustained-release formulations of bupropion (1.53%), and metoprolol tartrate and metoprolol succinate (1.48%). Among pairs with distinct indications, the pairs associated with the highest potential-error rates were tramadol and trazodone (2.20%) and bupropion and buspirone (1.31%). For LASA drug pairs found to be associated with actual errors, the estimated error rates were as follows: lamivudine and lamotrigine, 0.003% (95% confidence interval [CI], 0–0.01%); carbamazepine and oxcarbazepine, 0.03% (95% CI, 0–0.09%); and morphine and hydromorphone, 0.02% (95% CI, 0–0.05%). Conclusion Through the use of administrative databases, potential LASA errors that could be reviewed for an actual error via chart review were identified. While a high rate of potential LASA errors was detected, the number of actual errors identified was low.