Repositorio Institucional UCSC (Univ. Católica de la Santísima Concepción)
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Shape and spin state model of contact binary (388188) 2006 DP14 using combined radar and optical observations
Get PDFContact binaries are found throughout the solar system. The recent discovery of Selam, the satellite of MBA (152830) Dinkinesh, by the NASA LUCY mission has made it clear that the term ‘contact binary’ covers a variety of different types of bi-modal mass distributions and formation mechanisms. Only by modelling more contact binaries can this population be properly understood. We determined a spin state and shape model for the Apollo group contact binary asteroid (388188) 2006 DP14 using ground-based optical and radar observations collected between 2014 and 2023. Radar delay-Doppler images and continuous wave spectra were collected over two days in February 2014, while 16 lightcurves in the Cousins R and SDSS-r filters were collected in 2014, 2022 and 2023. We modelled the spin state using convex inversion before using the SHAPE modelling software to include the radar observations in modelling concavities and the distinctive neck structure connecting the two lobes. We find a spin state with a period of (5.7860±0.0001) hours and pole solution of = (180±121)◦ and = (−80±7)◦ with morphology indicating a 520 m long bi-lobed shape. The model’s asymmetrical bi-modal mass distribution resembles other small NEA contact binaries such as (85990) 1999 JV6 or (8567) 1996 HW1, which also feature a smaller ‘head’ attached to a larger ‘body’. The final model features a crater on the larger lobe, similar to several other modelled contact binaries. The model’s resolution is 25 m, comparable to that of the radar images used
Gauging proximity to failure in the bench press: generalized velocity-based vs. %1RM-repetitions-to-failure approaches
Get PDFBackground
This study compared the accuracy of three generalized approaches for estimating proximity to failure during the Smith machine bench press: (i) the relationship between relative load (%1RM) and maximum repetitions performed to failure (%1RM-RTF), (ii) the relationship between maximum repetitions to failure and fastest set velocity (RTF-velocity), and (iii) the relationship between repetitions left in reserve (RIR) and lifting velocity (RIR-velocity).
Methods
Nineteen physically active men (22.9 ± 2.7 years old) with at least two years of resistance training experience participated. Their 1-repetition maximum (1RM = 86.8 ± 16.7 kg) was determined during the first session. In the second session, participants performed single sets to failure at 60% and 80% 1RM, with proximity to failure (2RIR and 4RIR) estimated using each approach.
Results
The RIR-velocity relationship was the only approach that did not significantly deviate from the intended RIR (errors = -0.4 to 0.6 repetitions). In contrast, both the %1RM-RTF and RTF-velocity relationships overestimated the intended RIR at 60%1RM for both 2RIR (2.9 and 5.8 repetitions, respectively) and 4RIR (2.8 and 5.7 repetitions, respectively), while no significant differences were observed at 80%1RM (errors = -0.6 to 0.9 repetitions). The RIR-velocity relationship generally demonstrated the lowest absolute errors compared to the actual RIR (1.3 ± 0.7 repetitions), with greater differences compared to the other two approaches at lighter loads and closer proximities to failure.
Conclusions
In the absence of individual relationships, the general RIR-velocity relationship should be used by coaches to control the proximity to failure of their athletes during the bench press exercise
Seismic damage assessment of steel storage racks subjected to subduction earthquakes using a simplified method
Get PDFThe incremental dynamic analysis is procedure highly used in the evaluation of structural systems and seismic design parameters for the linear design methods traditionally used in current building codes. The use of this methodology has been extended to industrial structures; however, in the case of steel racks subjected to subduction earthquakes such as the one in Chile, the procedure presents limitations in the post MCE scaling stage due to the high seismic demand, which does not allow its use. In this research, the seismic evaluation of steel storage racks is studied using a dynamic decremental analysis (DDA). The numerical research aims at a methodology proposed to evaluate seismic damage in steel storage racks, considering operational continuity, life safety and collapse prevention levels. A total of 4840 nonlinear models were performed to establish the performance levels, supported by the principles of the IDA according to FEMA P695. The MCE is used to scale the seismic records, however, a decremental scaling process is applied to identify the performance gap between the design intensity and the MCE intensity. The results obtained showed that the archetypes with lower load levels and lower height exhibited higher performance levels in the down-aisle direction compared to the transverse direction. In addition, the proposed methodology allows obtaining a performance level considering the seismic forces scaled to the MCE level through a methodology on steel racks, which had not been possible to evaluate using the IDA. Finally, the main problem in the study of steel racks design is to ensure the stability in the cross-aisle direction and stability of the stored goods in that direction
Relación entre la variabilidad de la frecuencia cardiaca, nivel de actividad física y factores sociodemográficos en adultos jóvenes: estudio transversal
Get PDFIntroduction: heart rate variability is a key indicator of cardiovascular health and autonomic balance, influenced by various factors such as age and stress. Objective: to relate heart rate variability to body composition, physical activity levels, sleep quality, and self-perceived stress in young Chilean adults with low cardiometabolic risk. Methodology: a cross-sectional study was conducted in 2024 with the participation of 32 young adults (18 to 30 years old), selected based on inclusion criteria related to adequate physical activity levels and the absence of chronic diseases. The analysis considered variables such as body composition, sleep quality, stress levels, physical activity levels, and heart rate variability, with the latter measured over a 5-minute resting period. Results: age showed a significant negative relationship with RMSSD (β = -0.43, t = -2.48, p = .02), indicating a decrease in parasympathetic activity as age increases. Self-perceived stress, however, did not show a significant impact on RMSSD (β = .09, p = .60) or the RR/RMSSD ratio (β = -0.37, p = .04). Discussion: the findings highlight the importance of heart rate variability as an indicator of autonomic health, emphasizing how age and stress impact vagal modulation. These results reinforce the need to integrate autonomic monitoring into preventive strategies to improve cardiovascular health. Conclusion: heart rate variability is significantly related to age and self-perceived stress. These findings underline the importance of integrating autonomic monitoring into preventive health strategies
Melnikov method for perturbed completely integrable systems
No full textWe consider a completely integrable system of differential equations in arbitrary dimensions whose phase space contains an open set foliated by periodic orbits. This research analyzes the persistence and stability of the periodic orbits under a nonlinear periodic perturbation. For this purpose, we use the Melnikov method and Floquet theory to establish conditions for the existence and stability of periodic orbits. Our approach considers periods of the unperturbed orbits depending on the integrals and constant periods. In the applications, we deal with both cases. Precisely, we study the existence of periodic orbits in a perturbed generalized Euler system. In the degenerate case, we analyze the existence and stability of periodic orbits for a perturbed harmonic oscillator
SARS-CoV-2 Main Protease inhibitors in trace constituents from Algerian herbal medicines using in silico approaches
Get PDFSince antiquity, еssential oils are considered as a source of bioactive molecules. Some of them have been shown to possess antiviral activities against various virus strains, among them SARS-CoV-2.
The aim of this study is the search for compounds, among minor components extracted from different aromatic and medicinal plants collected from Algerian pharmacopeia, which may posses possible COVID-19 antiviral activities, by molecular docking in the active site of SARS-CoV-2 main protease.
Materials and methods. Thus, in this study 66 compounds which are declared at traces amount by authors in the composition of the essential oils, and selected from 9 Algerian medicinal plants were docked in the active site of SARS-CoV-2 main protease as possible inhibitors of SARS-CoV-2.
Results. The obtained result shows that only Cembrene constitutes the structure with the best affinity in the binding site of the enzyme with a Bioavailability Score “ABS” equal to 0.55 which confirm non Lipinski violations. However, the compound is predicted not orally bioavailable, because too lipophilic (lipophilicity: Log Po/w (XLOGP3)=6.04>+5.0) and less polar (polarity: TPSA=0.00Ų<20 Ų), and it is also predicted as not absorbed, not brain penetrant and not subject to active efflux from the CNS or to the gastrointestinal lumen.
Conclusion. This result deserves to be more detailed and either confirmed or invalidated with a view to better and rational exploitation
MyAphasia: A mobile application for the treatment of Aphasia in a hospital environment
No full textAphasia, an alteration in the ability to use language, is a common consequence of stroke. Aphasia is treated by multidisciplinary teams including speech and language therapists. However, due to high workload and scarce resources, patients may not get enough therapy time. This article proposes MyAphasia, an application to help speech and language therapists in the treatment of aphasia in the acute phase, by assigning activities for the patient to perform independently. The application was evaluated by 11 speech and language therapists for 2 days. The results are promising: therapists found MyAphasia easy to use and helpful, potentially saving time and resources
Novel Similarity Measure for Pythagorean and Intuitionistic Fuzzy Sets
No full textIntuitionistic Fuzzy Sets (IFS) and Pythagorean Fuzzy Sets (PFS) offer robust frameworks for handling uncertainty and vagueness in decision-making. This paper presents a novel chi-square similarity measure designed specifically for IFS and PFS. Traditional similarity measures often struggle to adequately handle the complexities inherent in these fuzzy set models. Through various numerical discussions spanning diverse domains, we demonstrate the effectiveness and versatility of the proposed measure. The case studies conducted illustrate its superiority over existing similarity measures in capturing nuanced relationships within fuzzy sets, offering valuable insights for decision-makers operating in uncertain environments. This research significantly contributes to advancing similarity measures in fuzzy set theory, providing practical tools to navigate complex decision-making scenarios