2,949 research outputs found

    Why bayesian “evidence for H1” in one condition and bayesian “evidence for H0” in another condition does not mean good-enough bayesian evidence for a difference between the conditions

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    Psychologists are often interested in whether an independent variable has a different effect in condition A than in condition B. To test such a question, one needs to directly compare the effect of that variable in the two conditions (i.e., test the interaction). Yet many researchers tend to stop when they find a significant test in one condition and a nonsignificant test in the other condition, deeming this as sufficient evidence for a difference between the two conditions. In this Tutorial, we aim to raise awareness of this inferential mistake when Bayes factors are used with conventional cutoffs to draw conclusions. For instance, some researchers might falsely conclude that there must be good-enough evidence for the interaction if they find good-enough Bayesian evidence for the alternative hypothesis, H1, in condition A and good-enough Bayesian evidence for the null hypothesis, H0, in condition B. The case study we introduce highlights that ignoring the test of the interaction can lead to unjustified conclusions and demonstrates that the principle that any assertion about the existence of an interaction necessitates the direct comparison of the conditions is as true for Bayesian as it is for frequentist statistics. We provide an R script of the analyses of the case study and a Shiny app that can be used with a 2 × 2 design to develop intuitions on this issue, and we introduce a rule of thumb with which one can estimate the sample size one might need to have a well-powered design

    Shock temperature measurements in metals: New results for an Fe alloy

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    The temperature of a Fe-Cr-Ni alloy (304 stainless steel) has been measured during shock compression using a high-speed radiometric technique. Experiments were performed on high-quality thick films deposited on sapphire and LiF windows. The samples had no observable porosity or defects and closely meet the ideal criteria for shock temperature measurements. Data obtained with both Al_2O_3 and LiF windows are internally consistent, indicating that they remain transparent to high pressures and are thus suitable windows for shock temperature measurements. Our data yield stainless steel melting temperatures ranging from 4570±310K at 138 GPa to 5710±340 K at 215 GPa, and additionally provide bounds on the initial Hugoniot temperatures of the sample between 5600±340 K at 234 GPa (near the solidus) and 6580±440 K at 283 (in the liquid field). Taken together, these data define a smooth curve for melting of the alloy up to 271 GPa and 5860 K, which should represent a point on the Iiquidus. Melting along the Hugoniot begins at approximately 234 GPa and 5600 K, as compared with 242 GPa and 6400 K for pure Fe. At the pressure of the inner core-outer core boundary, the melting point of 304 stainless steel is lower than that of pure Fe by ≈ 1450 K, as compared with only 110 K at 1 atm. These results demonstrate that upon alloying with Ni and Cr the melting point depression of Fe and thus material likely to comprise the inner core increases with increasing pressure

    Shock Temperature of Stainless Steel and a High Pressure - High Temperature Constraint on Thermal Diffusivity of Al_2O_3

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    Time dependent shock temperatures were measured for stainless steel (SS) films in contact with transparent anvils. The anvil/window material was the same as the driver material so that there would be symmetric heat flow from the sample. Inferred Hugoniot temperatures, T_h , of 5800–7500 K at 232–321 GPa are consistent with previous measurements in SS. Temperatures at the film‐anvil interface (T_i ), which are more directly measured than T_h , indicate that T_i did not decrease measurably during the approximately 250 ns that the shock wave was in Al_2O_3 or LiF anvils. Thus an upper bound is obtained for the thermal diffusivity of Al_2O_3 at the metal/anvil interface at 230 GPa and 6000K of κ≤0.00096 cm_2/s. This is a factor of 17 lower than previously calculated values, resulting in a decrease of the inferred T_h by 730 k. The observed shock temperatures are combined with temperatures calculated from measured Hugoniots and are used to calculate thermal conductivities of Al_2O_3. Also we note that since there was no measurable intensity decrease during the time when the shock wave propagated through the window, we infer from this that Al_2O_3 remained transparent while in the shocked state. Thus sapphire is a good window material to at least 250 GPa for shock temperature measurements for metals

    Upgrading Marine Ecosystem Restoration Using Ecological-Social Concepts

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    Conservation and environmental management are principal countermeasures to the degradation of marine ecosystems and their services. However, in many cases, current practices are insufficient to reverse ecosystem declines. We suggest that restoration ecology, the science underlying the concepts and tools needed to restore ecosystems, must be recognized as an integral element for marine conservation and environmental management. Marine restoration ecology is a young scientific discipline, often with gaps between its application and the supporting science. Bridging these gaps is essential to using restoration as an effective management tool and reversing the decline of marine ecosystems and their services. Ecological restoration should address objectives that include improved ecosystem services, and it therefore should encompass social ecological elements rather than focusing solely on ecological parameters. We recommend using existing management frameworks to identify clear restoration targets, to apply quantitative tools for assessment, and to make the re-establishment of ecosystem services a criterion for success

    Measurement of ocular surface protection under natural blink conditions

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    abstract: Purpose: To evaluate a new method of measuring ocular exposure in the context of a natural blink pattern through analysis of the variables tear film breakup time (TFBUT), interblink interval (IBI), and tear film breakup area (BUA). Methods: The traditional methodology (Forced-Stare [FS]) measures TFBUT and IBI separately. TFBUT is measured under forced-stare conditions by an examiner using a stopwatch, while IBI is measured as the subject watches television. The new methodology (video capture manual analysis [VCMA]) involves retrospective analysis of video data of fluorescein-stained eyes taken through a slit lamp while the subject watches television, and provides TFBUT and BUA for each IBI during the 1-minute video under natural blink conditions. The FS and VCMA methods were directly compared in the same set of dry-eye subjects. The VCMA method was evaluated for the ability to discriminate between dry-eye subjects and normal subjects. The VCMA method was further evaluated in the dry eye subjects for the ability to detect a treatment effect before, and 10 minutes after, bilateral instillation of an artificial tear solution. Results: Ten normal subjects and 17 dry-eye subjects were studied. In the dry-eye subjects, the two methods differed with respect to mean TFBUTs (5.82 seconds, FS; 3.98 seconds, VCMA; P = 0.002). The FS variables alone (TFBUT, IBI) were not able to successfully distinguish between the dry-eye and normal subjects, whereas the additional VCMA variables, both derived and observed (BUA, BUA/IBI, breakup rate), were able to successfully distinguish between the dry-eye and normal subjects in a statistically significant fashion. TFBUT (P = 0.034) and BUA/IBI (P = 0.001) were able to distinguish the treatment effect of artificial tears in dry-eye subjects. Conclusion: The VCMA methodology provides a clinically relevant analysis of tear film stability measured in the context of a natural blink pattern.The final version of this article, as published in Clinical Ophthalmology, can be viewed online at: https://www.dovepress.com/measurement-of-ocular-surface-protection-under-natural-blink-condition-peer-reviewed-article-OPT

    Marginalized Populations’ Access to Transit: Journeys from Home and Work to Transit

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    Previous scholarship has shown that low-income individuals who also might identify as racial, ethnic, and gender minorities (such as transgender and gender nonconforming) are more likely to be dependent on public transportation. What remains understudied is how these marginalized groups, given their intersectional identities of oppression, might experience transit. The primary research question guiding this project is how do people with intersecting marginal identities experience social exclusion as they travel via mass transit? To answer the above research question, we employed a photovoice methodology and video-call interviewing, in Portland, OR, and Salt Lake City, UT. Across these two sites we interviewed 35 BIPOC (Black, Indigenous and other People of Color) with an income level less than 35,000perpersonperyearor35,000 per person per year or 70,000 per family per year who use transit regularly, who were ethnically diverse, and included immigrants and people with other marginalized identities. In the interviews we found that people from these historically marginalized communities experience economic barriers, discrimination, harassment, and violence on transit and in public areas such as sidewalks, bus stops, and transit platforms when accessing transit related to their intersecting identities (e.g., being a woman of color). We examined how to make transit more accessible; for example, transit passes for low-income individuals, higher frequency of buses, lighting in dark areas, Spanish messaging in stations and on buses, to mention a few. We found that transit workers were key to feelings of safety by marginalized riders, where they could create a sense of welcome and community and fairly and consistently support policies that facilitated access for all. In addition, technology could be a mechanism for safety and ease of travel, but also widen socioeconomic gaps. Our findings are a starting point about what not only Salt Lake City and Portland planners, policymakers, social service providers, and case managers can do, but also what other municipalities could expect in terms of improving transportation and services for these vulnerable populations
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