1,623 research outputs found
Accuracy of Wrist-Worn Monitors while Walking in Lower Limb Prosthetic Users
TACSM Abstract
Accuracy of Wrist-Worn Monitors while Walking in Lower Limb Prosthetic Users
BRIAN G. BURKHOLDER and JOHN D. SMITH
Department of Counseling, Health, & Kinesiology, Texas A&M University-San Antonio, San Antonio, TX
Category: Undergraduate
Advisor / Mentor: Smith, John ([email protected])
ABSTRACT
Wrist-worn activity monitors are extremely popular among the general population. These monitors are used to track activity for purposes to lose weight, get healthy, improve performance, and other reasons. While many studies have looked at the accuracy of these monitors in individuals without amputations, there has yet to be any that have examined these monitors in those who use lower-limb prosthetics. PURPOSE: to determine the accuracy of wrist-worn activity monitors in individuals using lower-limb prosthetics. METHODS: Thirty-four men and women (Age: 48.8±14.2 yrs, Ht: 176.9±11.5 cm, Wt: 88.3±21.1 kg, BMI: 28.3±5.3) with right-, left-leg, or bilateral above and below the knee amputations were fitted with a Polar Loop (PL) and a Fitbit ChargeTM (FC) on the left wrist, and an Omron HJ-112 (OM) pedometer on the left hip. After resetting the monitors, they then walked 140m at a self-selected pace followed by the investigator who counted steps with a standard lab hand-tally counter for actual counts (AC). At the conclusion of the walk, step counts were recorded from all devices. A repeated measures ANOVA was used to determine differences in counts registered by the monitors and those registered by AC. Single measure intraclass correlation (ICC) from a two-way random effects ANOVA was used to assess the agreement between AC and monitor counts, with ≥ 0.90 considered high agreement, 0.80 to 0.89 moderate agreement, and ≤ 0.79 low agreement. Bland-Altman plots of AC vs. counts registered by the monitors were used to provide an indication of over/under representation of steps and agreement between the measures. Percent error was calculated as [(counts detected by monitor – AC) / AC] x 100. Alpha was set at .05 for all statistical tests. RESULTS: There was a significant difference between counts, F(3, 30)=8.8, p=.001, with pairwise comparisons indicating PL was significantly lower than AC, p=.001. There was no significant difference between AC and FC (p\u3e.05) or between AC and OM (p\u3e.05). Agreement according to ICC between AC and PL was low (α=.71, ICC=.42 to .86), between AC and FC was moderate (α =.81, ICC=.61 to .90), and between AC and OM was high (α =.93, ICC=.86 to .97). Bland Altman plots indicate lowest agreement between AC and PL, and with highest agreement between AC and OM. Percent error was greatest with PL (16±12%), lower with FC (8.9±8.9%), and least with OM (4.1±7.3%). CONCLUSION: It seems that for this population who might consider wearing either the PL or the FC, the FC would be a better choice given its greater accuracy. Interestingly, the OM is the superior device for counting steps
Measurements of the ClO radical vibrational band intensity and the ClO + ClO + M reaction product
There is considerable interest in the kinetics and concentrations of free radicals in the stratosphere. Chlorine monoxide is a critically important radical because of its role in catalytic cycles for ozone depletion. Depletion occurs under a wide variety of conditions including the Antarctic spring when unusual mechanisms such as the BrO sub x/ClO sub x, ClO dimer (Cl sub 2 O sub 2), and ClO sub x/HO sub x cycles are suggested to operate. Infrared spectroscopy is one of the methods used to measure ClO in the stratosphere (Menzies 1979 and 1983; Mumma et al., 1983). To aid the quantification of such infrared measurements, researchers measured the ClO ground state fundamental band intensity
Riesz transform characterization of Hardy spaces associated with Schr\"odinger operators with compactly supported potentials
Let L=-\Delta+V be a Schr\"odinger operator on R^d, d\geq 3. We assume that V
is a nonnegative, compactly supported potential that belongs to L^p(R^d), for
some p>d/2. Let K_t be the semigroup generated by -L. We say that an
L^1(R^d)-function f belongs to the Hardy space H_L^1 associated with L if
sup_{t>0} |K_t f| belongs to L^1(R^d). We prove that f\in H_L^1 if and only if
R_j f \in L^1(R^d) for j=1,...,d, where R_j= \frac{d}{dx_j} L^{-1/2} are the
Riesz transforms associated with L.Comment: 6 page
Examining the Potential and Pitfalls of ChatGPT in Science and Engineering Problem-Solving
The study explores the capabilities of OpenAI's ChatGPT in solving different
types of physics problems. ChatGPT (with GPT-4) was queried to solve a total of
40 problems from a college-level engineering physics course. These problems
ranged from well-specified problems, where all data required for solving the
problem was provided, to under-specified, real-world problems where not all
necessary data were given. Our findings show that ChatGPT could successfully
solve 62.5% of the well-specified problems, but its accuracy drops to 8.3% for
under-specified problems. Analysis of the model's incorrect solutions revealed
three distinct failure modes: 1) failure to construct accurate models of the
physical world, 2) failure to make reasonable assumptions about missing data,
and 3) calculation errors. The study offers implications for how to leverage
LLM-augmented instructional materials to enhance STEM education. The insights
also contribute to the broader discourse on AI's strengths and limitations,
serving both educators aiming to leverage the technology and researchers
investigating human-AI collaboration frameworks for problem-solving and
decision-making.Comment: 12 pages, 2 figure
Modeling approach to regime shifts of primary production in shallow coastal ecosystems
Pristine coastal shallow systems are usually dominated by extensive meadows
of seagrass species, which are assumed to take advantage of nutrient supply
from sediment. An increasing nutrient input is thought to favour phytoplankton,
epiphytic microalgae, as well as opportunistic ephemeral macroalgae that
coexist with seagrasses. The primary cause of shifts and succession in the
macrophyte community is the increase of nutrient load to water; however
temperature plays also an important role. A competition model between rooted
seagrass (Zostera marina), macroalgae (Ulva sp), and phytoplankton has been
developed to analyse the succession of primary producer communities in these
systems. Successions of dominance states, with different resilience
characteristics, are found when modifying the input of nutrients and the
seasonal temperature and light intensity forcing.Comment: 33 pages, including 10 figures. To appear in Ecological Complexit
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