Tag: pubmed

J Chin Med Assoc. 2023 Sep 19. doi: 10.1097/JCMA.0000000000000999. Online ahead of print.

ABSTRACT

BACKGROUND: Population aging is emerging as an increasingly acute challenge for countries around the world. One particular manifestation of this phenomenon is the impact of osteoporosis on individuals and national health systems. Previous studies of risk factors for osteoporosis were conducted using traditional statistical methods, but more recent efforts have turned to machine learning approaches. Most such efforts, however, treat the target variable (bone mineral density or fracture rate) as a categorical one which provides no quantitative information. The present study uses five different machine learning methods to analyze the risk factors for T-score of bone mineral density, seeking to: (1) Compare the prediction accuracy between different machine learning methods and traditional multiple linear regression and (2) rank the importance of 25 different risk factors.

METHODS: The study sample includes 24,412 women aged > 55 y/o with 25 related variables, applying traditional multiple linear regression (MLR) and five different machine learning methods: classification and regression tree (CART), Naïve Bayes (NB), Random Forest (RF), stochastic gradient boosting (SGB), and eXtreme Gradient Boosting (XGBoost). The metrics used for model performance comparisons are the symmetric mean absolute percentage error, and relative absolute error, root relative squared error and root mean squared error.

RESULTS: Machine learning approaches outperformed MLR for all four prediction errors. The average importance ranking of each factor generated by the machine learning methods indicate that age is the most important factor determining T-score, followed by eGFR, BMI, UA, and education level.

CONCLUSION: In a group of women aged > 55 years, we demonstrated that machine learning methods provide superior performance in estimating T-Score, with age being the most important impact factor, followed by eGFR, BMI, UA, and education level.

PMID:37729604 | DOI:10.1097/JCMA.0000000000000999

Nano Lett. 2023 Sep 20. doi: 10.1021/acs.nanolett.3c01714. Online ahead of print.

ABSTRACT

Wear of sliding contacts causes device failure and energy costs; however, the microscopic principle in activating wear of the interfaces under stress is still open. Here, the typical nanoscale wear, in the case of silicon against silicon dioxide, is investigated by single-asperity wear experiments and density functional theory calculations. The tests demonstrate that the wear rate of silicon in ambient air increases exponentially with stress and does not obey classical Archard’s law. Series calculations of atomistic wear reactions generally reveal that the mechanical stress linearly drives the electron transfer to activate the sequential formation and rupture of interfacial bonds in the atomistic wear process. The atomistic wear model is thus resolved by combining the present stress-driven electron transfer model with Maxwell-Boltzmann statistics. This work may advance electronic insights into the law of nanoscale wear for understanding and controlling wear and manufacturing of material surfaces.

PMID:37729549 | DOI:10.1021/acs.nanolett.3c01714

Am J Manag Care. 2023 Sep;29(9):455-462. doi: 10.37765/ajmc.2023.89425.

ABSTRACT

OBJECTIVES: To determine agreement between variables capturing the primary payer at cancer diagnosis across the Pennsylvania Cancer Registry (PCR) and statewide facility discharge records (Pennsylvania Health Care Cost Containment Council [PHC4]) for adults younger than 65 years, and to specifically examine factors associated with misclassification of Medicaid status in the registry given the role of managed care.

STUDY DESIGN: Cross-sectional analysis of the primary cancer cases among adults aged 21 to 64 years in the PCR from 2010 to 2016 linked to the PHC4 facility visit records.

METHODS: We assessed agreement of payer at diagnosis (Medicare, Medicaid, private, other, uninsured, unknown) across data sources, including positive predictive value (PPV) and sensitivity, using the PHC4 records as the gold standard. The probability of misclassifying Medicaid in registry was estimated using multivariate logit models.

RESULTS: Agreement of payers was high for private insurance (PPV, 89.7%; sensitivity, 83.6%), but there was misclassification and/or underreporting of Medicaid in the registry (PPV, 80%; sensitivity, 58%). Among cases with “other” and “unknown” insurance, 73.8% and 62.1%, respectively, had private insurance according to the PHC4 records. Medicaid managed care was associated with a statistically significant increase of 12.6 percentage points (95% CI, 9.4-15.8) in the probability of misclassifying Medicaid enrollment as private insurance in the registry.

CONCLUSIONS: Findings suggest caution in conducting and interpreting research using insurance variables in cancer registries.

PMID:37729528 | DOI:10.37765/ajmc.2023.89425

J Strength Cond Res. 2023 Oct 1;37(10):2071-2075. doi: 10.1519/JSC.0000000000004584.

ABSTRACT

Buso, D, Willardson, JM, and Shafer, AB. Research note: Effects of medicine wall ball throws with whole-body vibration on bat swing performance in collegiate baseball players. J Strength Cond Res 37(10): 2071-2075, 2023-The purpose of this study was to examine the effect of medicine ball wall throws performed with whole-body vibration on bat swing performance in 13 highly trained collegiate baseball players. The experimental session involved the athletes’ usual warm-up followed by baseline bat swings. The baseline bat swings were followed by 3 sets of 5 medicine ball wall throws while standing on a whole-body vibration platform set at 40 Hz and with 30 seconds rest between sets. Subjects then rested passively for 5 minutes before taking post-test bat swings. Performance was evaluated with bat speed (m·second-1), time to contact (secs), rotational acceleration (G’s), and exit velocity (m·second-1). Paired t tests were used to compare baseline and post-test values (p ≤ 0.05). Effect size (d) statistics were also calculated to determine the magnitude of treatment effects. It was found that bat speed (p = 0.02; d = 0.22) and exit velocity (p = 0.03; d = 0.48) were significantly faster versus baseline, whereas rotational acceleration (p = 0.10; d = 0.23) and time to contact (p = 0.44; d = -0.12) were not significantly different from baseline, respectively. These results suggest that the addition of medicine ball wall throws with whole-body vibration can significantly increase key parameters of bat swing performance. Practitioners and coaches may consider including these combined exercise stimuli as part of workouts or during games for potentially greater success at the plate.

PMID:37729518 | DOI:10.1519/JSC.0000000000004584

J Strength Cond Res. 2023 Oct 1;37(10):2016-2022. doi: 10.1519/JSC.0000000000004502.

ABSTRACT

Faulhaber, M, Schneider, S, Rausch, LK, Dünnwald, T, Menz, V, Gatterer, H, Kennedy, MD, and Schobersberger, W. Repeated short-term bouts of hyperoxia improve aerobic performance in acute hypoxia. J Strength Cond Res 37(10): 2016-2022, 2023-This study aimed to test the effects of repeated short-term bouts of hyperoxia on maximal 5-minute cycling performance under acute hypoxic conditions (3,200 m). Seventeen healthy and recreationally trained individuals (7 women and 10 men) participated in this randomized placebo-controlled cross-over trial. The procedures included a maximal cycle ergometer test and 3 maximal 5-minute cycling time trials (TTs). TT1 took place in normoxia and served for habituation and reference. TT2 and TT3 were conducted in normobaric hypoxia (15.0% inspiratory fraction of oxygen). During TT2 and TT3, the subjects were breathing through a face mask during five 15-second periods. The face mask was connected through a nonrebreathing T valve to a 300-L bag filled with 100% oxygen (intermittent hyperoxia) or ambient hypoxic air (placebo). The main outcome was the mean power output during the TT. Statistical significance level was set at p < 0.05. The mean power output was higher in the intermittent hyperoxia compared with the placebo condition (255.5 ± 49.6 W vs. 247.4 ± 48.2 W, p = 0.001). Blood lactate concentration and ratings of perceived exertion were significantly lower by about 9.7 and 7.3%, respectively, in the intermittent hyperoxia compared with the placebo condition, whereas heart rate values were unchanged. IH application increased arterial oxygen saturation (82.9 ± 2.6% to 92.4 ± 3.3%, p < 0.001). Repeated 15-second bouts of hyperoxia, applied during high-intensity exercise in hypoxia, are sufficient to increase power output. Future studies should focus on potential dose-response effects and the involved mechanisms.

PMID:37729514 | DOI:10.1519/JSC.0000000000004502

J Strength Cond Res. 2023 Oct 1;37(10):1929-1938. doi: 10.1519/JSC.0000000000004498.

ABSTRACT

Nagatani, T, Kendall, KL, Guppy, SN, Poon, WCK, and Haff, GG. Effect of 3 different set configurations on kinematic variables and internal loads during a power snatch session. J Strength Cond Res 37(10): 1929-1938, 2023-The aim of this study was to investigate the effect of 3 different set configurations on kinematic variables and internal loads during multiple sets performed with the power snatch. Ten strength-power athletes with at least 6 months of training experience performing the power snatch participated in this study, which consisted of 3 experimental protocols performed in a randomized repeated-measures design. The 3 protocols involved performing the power snatch for 3 sets of 5 repetitions at an average load of 75% 1 repetition maximum with a traditional (TRAD), cluster (CLU), or ascending cluster (A-CLU) protocol, where the training load was progressively increased across the set. Kinematic variables and internal loads (heart rate, blood lactate, and rate of perceived exertion) were measured during each protocol. The athletes maintained peak velocity (PV) and peak power (PP) and exhibited lower internal loads during CLU sets when compared with TRAD sets, whereas they displayed significant decreases in PV during TRAD sets. However, there were no statistically significant differences in PV and PP responses between the TRAD and CLU protocol. The athletes exhibited a significant decrease in PV, whereas PP was increased across each set in the A-CLU protocol, with lower internal loads observed compared with the TRAD protocol. Overall, the training loads used in this study do not appear to maximize the benefits of using CLU set during 3 sets of power snatches performed for 5 repetitions. In addition, A-CLU sets may potentially be useful as a means of maximizing the power output of the athlete.

PMID:37729510 | DOI:10.1519/JSC.0000000000004498

J Strength Cond Res. 2023 Oct 1;37(10):1924-1928. doi: 10.1519/JSC.0000000000004494.

ABSTRACT

Trahey, KM, Lapp, EM, Talipan, TN, Guydan, TJ, Krupka, AJ, and Ellis, CE. The effect of lifting straps on deadlift performance in females. J Strength Cond Res 37(10): 1924-1928, 2023-Using lifting straps (LS) while deadlifting may increase the total number of repetitions performed and barbell velocity, and preserve grip strength; however, research in this area has only been conducted on men. This study investigated the effects of lifting straps on the total number of repetitions, mean and peak barbell velocity, and grip strength during the deadlift exercise in women. Ten women (20.1 ± 1.1 years; 165.4 ± 5.6 cm, 68.9 ± 10.3 kg) with 3.2 ± 2.1 years of resistance training experience participated in the study. After completing a 1-repetition maximum (1RM) test without LS, subjects completed 2 protocols: performing 3 sets of as many repetitions as possible of 80% 1RM with lifting straps (WS) and without lifting straps (NS). During both protocols, mean and peak barbell velocity were measured during each set, and grip strength was recorded before deadlifting and after each set. Repeated-measures analysis of variance were used to examine differences in the variables of interest, with an alpha level of 0.05 used to establish statistical significance. The WS condition allowed participants to perform significantly more reps while resulting in no statistically significant differences in mean or peak barbell velocity. The magnitude of grip strength loss was significantly lower during the WS condition. Results indicate that using LS while deadlifting allows women to perform more repetitions with greater preserved grip strength without negatively affecting barbell velocity. Thus, LS appear beneficial for deadlift performance in women and should be considered during resistance training involving the deadlift exercise.

PMID:37729509 | DOI:10.1519/JSC.0000000000004494

Int J Prosthodont. 2023 Sep 20;0(0):0. doi: 10.11607/ijp.8673. Online ahead of print.

ABSTRACT

PURPOSE: This study aimed to evaluate the tensile strength of five different thicknesses of two resin cements placed between two titanium surfaces, before and after ageing.

MATERIALS AND METHODS: One hundred titanium 5 grade models composed of two surfaces simulating a semiprecision attachment for overdenture and its housing in the framework, were used. Samples were cemented using two different resin cements (SoloCem and OT-Cem). Five groups representing five different cement thicknesses (from 50 to 250μm) were created by varying the housing diameter. A half of the sample underwent to a tensile strength test 24h after luting, while the other half after 30000 thermic cycles from 5°C to 55°C. Shapiro-Wilk and ANOVA with post-hoc tests were performed to relate the tensile strength to the variables: cement type, thermal ageing and cement thickness (p <0.05).

RESULTS: Statistical differences were found between the cements both at T0 and T1; the mean values of tensile strength of SoloCem were three times higher than those of OT-Cem. The thermic cycles determined a reduction of the tensile force values for both cements; statistical evidence was found only for the SoloCem except for the 100μm thickness group. Significant differences were also found between the cement thicknesses of both cements, with 50µm and 100μm expressed the best tensile strength. Most of the fractures were of cohesive nature.

CONCLUSION: SoloCem showed a higher tensile strength than OT-Cem but has been more stressed by the ageing. For each group the cement thickness influenced the tensile strength values with an inverse relationship.

PMID:37729489 | DOI:10.11607/ijp.8673

Int J Prosthodont. 2023 Sep 20;0(0):0-1. doi: 10.11607/ijp.8371. Online ahead of print.

ABSTRACT

PURPOSE: The objective of the study was to determine the values of 15 craniofacial linear distances in the Serbian ethnic group and the correlations between them that are predictive or can serve as proxy for OVD using and compare two methods of face-anthropometric and digital 2D face-photogrammetric measurement.

MATERIAL AND METHODS: A total of 90 adults were selected. Facial distance as a tool to measure the OVD was Sn-Gn – distance between septum of the nose (Sn) and tip of the chin (Gn). Face-anthropometric measurements were made with a Boley Gauge (Buffalo Dental Manufacturing Co.NY,USA). Digital 2D photogrammetric facial measurements were performed using the computer program DrCeph (FYI Technologies, USA).

RESULTS: Determined mean value for the distance Sn-Gn by face-anthropometric was Sn-Gn(f) X=63.55 and by face-photogrammetric was Sn-Gn(ph) X=63.56. Multivariate regression analysis revealed that Sn-Gn(f) depended on ExL-ExR(f) p<0.001, ZyL-ZyR(f) p=0.077, N-Sn(f) p=0.096, Sn-Sto(f) p=0.043 and gender and that Sn-Gn(ph) depended on ExL-ExR(ph) p<0.001, EnL-EnR(ph) p=0.029, N-Sn(ph) p=0.013, Sn-Sto(ph) p=0.001 and gender.

CONCLUSIONS: A comparison of facial anthropometry and digital 2D facial photogrammetry reveals no statistical significance differences in the values obtained and shows that facial photogrammetry could be a reliable method as a facial anthropometry.

PMID:37729487 | DOI:10.11607/ijp.8371

Int J Prosthodont. 2023 Sep 20;0(0):0. doi: 10.11607/ijp.8716. Online ahead of print.

ABSTRACT

PURPOSE: The aim of this study is to investigate the prevalence of (TMD) as well as their potential risk factors among postgraduate students.

MATERIALS AND METHODS: In this cross-sectional and correlation study, 1255 postgraduate students from different universities were recruited to answer Fonseca’s anamnestic index (FAI) in addition to collected demographic data and relevant dental history. Fonseca’s anamnestic index (FAI) was used to classify their TMD severity. Five hundred ninety-three participants, that had previous clinical/radiographic TMD reports, out of 1255 were included. Chi-square and fisher’s exact tests investigated the relation between each predictor and TMD at P≤.05. A logistic binary regression analysis examined the model fit using -2Log likelihood and Pseudo R2 tests at P≤.05.

RESULTS: Based on previous clinical/radiographic reports and on FAI, 73.4% of the participants had TMD, of which 57% had mild dysfunction, followed by moderate (31.7%), and severe (11.3%). There was a statistically significant association between sex, depression, lip/object biting and clenching with TMD (P <.001), where females were 2.302 times more likely to develop TMD than males. The combination of lip biting and clenching in a female dramatically increases the risk of TMD (-2 Log Likelihood =385.7, P<.001 and a Cox and Snell value = 0.315 and a Nagelkerke value = 0.395).

CONCLUSION: TMD seems to be highly prevalent among postgraduate students in Egypt, whereby female postgraduate students who bite their lips and/or grind their teeth are particularly highly prone to the condition. Object biting and depression could be also considered as risk factors.

PMID:37729484 | DOI:10.11607/ijp.8716