How Do Movement Patterns in Weightlifting (Clean) Change When Using Lighter or Heavier Barbell Loads?—A Comparison of Two Principal Component Analysis-Based Approaches to Studying Technique

This study compared whole body kinematics of the clean movement when lifting three different loads, implementing two data analysis approaches based on principal component analysis (PCA). Nine weightlifters were equipped with 39 markers and their motion captured with 8 Vicon cameras at 100 Hz. Lifts of 60, 85, and 95% of the one repetition maximum were analyzed. The first PCA (PCAtrial) analyzed variance among time-normed waveforms compiled from subjects and trials; the second PCA (PCAposture) analyzed postural positions compiled over time, subjects and trials. Load effects were identified through repeated measures ANOVAs with Bonferroni-corrected post-hocs and through Cousineau-Morey confidence intervals. PCAtrial scores differed in the first (p < 0.016, ηp2 = 0.694) and fifth (p < 0.006, ηp2 = 0.768) principal component, suggesting that increased barbell load produced higher initial elevation, lower squat position, wider feet position after squatting, and less inclined arms. PCAposture revealed significant timing differences in all components. We conclude, first, barbell load affects specific aspects of the movement pattern of the clean; second, the PCAtrial approach is better suited for detecting deviations from a mean motion trajectory and its results are easier to interpret; the PCAposture approach reveals coordination patterns and facilitates comparisons of postural speeds and accelerations.

SAT-453 Delayed TSH Elevation in Small for Gestational Age Infants: A Need for Second Screening?

The incidence of CH with a delayed TSH elevation was higher in ELBW and VLBW infants compared with infants weighing ≥1500 grams. Second screening should be considered in preterm neonates, low birth weight (LBW) and very low-birth weight (VLBW) neonates, ill and preterm newborns admitted to NICU, specimen collection within the first 24 hours of life, and multiple births (particularly same-sex twins). Purpose of this study was to determine incidence of delayed TSH elevation with or without congenital hypothyroidism in SGA infants and to Investigate necessity for second screening. Retrospective analysis was performed. 66 SGA newborns with 34-40 weeks’ gestation born at Keimyung University Dongsan Medical Center from 2015 to 2018 were enrolled. Primary screening was performed 48 hours - 7 days after birth. Second screening including venous TSH and venous free T4 at postnatal 8-40 days. Exclusion criteria were infants with congenital hypothyroidism at primary screening (NBS), descendants of mothers with immune thyroid disease, congenital malformations, renal, hepatic, and metabolic diseases, history of steroid or dopamine usage. Initial NBS were collected onto pre-printed filter at the age of 2-7 days by heel prick. (normal TSH < 10 mIU/L). Second sample was obtained at the age of 8-49 days by venous sampling (normal TSH < 5 mIU/L). TSH and free T4 were measured on venous samples with Cobas 8000 e801 (electrochemiluminescence, Roche, Diagnostics, Basel, Switzerland) using standard methods. Incidence of delayed TSH elevation was 27% (18/66). Of them number of transient hyperthyrotropinemia was 13. Mean TSH at initial elevation was 7.56 mIU/L and median age at initial TSH elevation was 18.6 days. Median age at resolution of TSH elevation was 41.5 days. Number of hypothyroidism undergoing l-thyroxine medication was 5. Mean TSH at initial elevation was 22.1 mIU/L. Median age at initial TSH elevation was 14 days. Mean peak TSH was 23.4 mIU/L. The presence of delayed TSH elevation was not related to very low birth weight. SGA infants might be at a risk of delayed TSH elevation. Considering 2nd screening test within 1 month. Further study with more SGA infants are needed. Limitation of this study was relative small number of patients and iodine status was not considered

Tsunami Observer: automatic system for estimate of tsunamigenicity of an earthquake

<p>In this talk the fully automatic system for estimate of tsunamigenicity of an earthquake is presented. The system is focused on simplicity and speed with usage of minimum of input data. The input dataset for the system includes (1) earthquake coordinates, (2) earthquake depth, (3) seismic moment, (4) focal mechanism. We use datasets provided by USGS and GEOFON. Upon receiving earthquake data the system performs the following consecutive actions. At first, the vector field of co-seismic bottom deformation is obtained using earthquake fault parameters and empirical relationships. Then the initial elevation in tsunami source is calculated and estimation of Soloviev-Imamura tsunami intensity is performed. Initial elevation is calculated taking into account vertical and horizontal components of bottom deformation, local bathymetry (GEBCO) and smoothing effect of water layer. An auxiliary study was conducted to obtain relationship between potential energy of initial elevation of water in tsunami source and intensity of resulting tsunami. More than 200 historical events from HTDB/WLD and NGDC/WDS databases was statistically processed. The obtained relationship is used to assess the intensity of tsunami generated by earthquake under consideration. Finally, if event is considered significant (energy > 10<sup>9</sup> J), the numerical simulation of propagation of tsunami waves is performed. As a result of numerical simulation, animations of wave propagation, distribution of maximum tsunami heights, and water surface time-histories in a number of given points are produced. Details of implementation, physical constraints, future development of system as well as 2-years experience of the system operation will be discussed during the talk.</p><p><strong>Acknowledgements</strong></p><p>This work was supported by the Russian Foundation for Basic Research, projects 20-07-01098, 20-35-70038, 19-05-00351.</p>

How the choice between nodal planes affects the estimate of tsunami hazard of an earthquake

<p>Usually tsunami warning is issued if a submarine earthquake is registered of magnitude exceeding a threshold, the value of which varies depending on the region where the earthquake took place and on the earthquake depth. Being simple and fast this approach is characterized by quite a low accuracy in the tsunami run-up heights estimate. The forecast accuracy can be improved if, instead of magnitude, we use the potential energy of the initial elevation in the tsunami source, calculated taking into account the earthquake focal mechanism. Automatic system for estimate of tsunami hazard using focal mechanism (Tsunami Observer, http://ocean.phys.msu.ru/projects/tsunami-observer/) was recently developed and implemented. Focal mechanisms derived from analysis of the recorded seismic waveforms has two possible solutions, i.e. two nodal planes. Short after an earthquake it is not possible to determine automatically which of the nodal planes is in fact the fault plane.</p><p>The main purpose of this study is to reveal a difference in estimates of the potential energy of the initial elevation obtained making use of the first (NP1) and the second (NP2) nodal planes. All earthquake data including focal mechanism solutions were extracted from the Bulletin of the International Seismological Centre. Totally we processed nearly 6000 earthquakes Mw>6 occurred within the time period 1976 – 2019. All calculations were performed by means of the Tsunami Observer system. It was established that the potential energy calculated with use of NP1 (E<sub>NP1</sub>) and NP2 (E<sub>NP2</sub>) datasets can vary more than an order. However for overwhelming majority of seismic events (96.3%) the difference does not exceed two times, for significant number of events (74.1%) the difference does not exceed 1.2 times. In our presentation, we shall provide detailed description of calculation methods we use and the distribution of the ratio E<sub>NP1</sub>/E<sub>NP2</sub>. Also we shall discuss the influence of the focal depth and magnitude on the ratio E<sub>NP1</sub>/E<sub>NP2</sub>.</p><p>Acknowledgements</p><p>This work was supported by the Russian Foundation for Basic Research, projects 19-05-00351, 20-07-01098, 20-35-70038</p>

Routinely Randomize Potential Sources of Measurement Reactivity to Estimate and Adjust for Biases in Subjective Reports

With the advent of online and app-based studies, researchers in psychology are making increasing use of repeated subjective reports. The new methods open up opportunities to study behavior in the field and to map causal processes, but they also pose new challenges. Recent work has added initial elevation bias to the list of common pitfalls; here, higher negative states (i.e., thoughts and feelings) are reported on the first day of assessment than on later days. This article showcases a new approach to addressing this and other measurement reactivity biases. Specifically, we employed a planned missingness design in a daily diary study of more than 1,300 individuals who were assessed over a period of up to 70 days to estimate and adjust for measurement reactivity biases. We found that day of first item presentation, item order, and item number were associated with only negligible bias: items were not answered differently depending on when and where they were shown. Initial elevation bias may thus be more limited than has previously been reported or it may act only at the level of the survey, not at the item level. We encourage researchers to make design choices that will allow them to routinely assess measurement reactivity biases in their studies. Specifically, we advocate the routine randomization of item display and order, as well as of the timing and frequency of measurement. Randomized planned missingness makes it possible to empirically gauge how fatigue, familiarity, and learning interact to bias responses.

Initial elevation bias in subjective reports

People’s reports of their thoughts, feelings, and behaviors are used in many fields of biomedical and social science. When these states have been studied over time, researchers have often observed an unpredicted and puzzling decrease with repeated assessment. When noted, this pattern has been called an “attenuation effect,” suggesting that the effect is due to bias in later reports. However, the pattern could also be consistent with an initial elevation bias. We present systematic, experimental investigations of this effect in four field studies (study 1: n = 870; study 2: n = 246; study 3: n = 870; study 4: n = 141). Findings show clear support for an initial elevation bias rather than a later decline. This bias is larger for reports of internal states than for behaviors and for negative mental states and physical symptoms than for positive states. We encourage increased awareness and investigation of this initial elevation bias in all research using subjective reports.

SRTM DEM-AIDED DEM EXTRACTION METHOD FOR ISLAND AND REEF

An SRTM DEM-aided DEM extraction method for island and reef is proposed to solve the problem of island and reef DEM extraction based on satellite imagery. The SRTM DEM is fully integrated into this method, namely, it is used to provide initial elevation for DEM and also to mark the sea area points in order to avoid the adverse effect of sea area image on DEM extraction. When determining elevations of grid points, only the valid land area points (VLPs) are taken into account. On the basis of initial elevation, the image coordinates of VLPs in multi-view images are determined and precise coordinates of conjugate points are obtained based on least square matching, then ground coordinates of VLPs are acquired by forward intersection. Finally, the elevations of VLPs are determined based on these object space points through data interpolation, and the sea area points are set as a uniform value. Experimental results show that the method can effectively solve the problem of island and reef DEM extraction. It can effectively extract DEM from island and reef satellite images regardless of the land area proportion, and island and reef can be completely extracted. Accuracy of the extracted DEM would improve with the increase of DEM resolution; when the resolution is relative high, the accuracy is consistent with SRTM DEM. The computational efficiency depends on the land area proportion and DEM resolution.