Higher Expenditure Research Articles

Opa1 and MT-Nd6 mutations induce early mitochondrial changes in the retina and prelaminar optic nerve of hereditary optic neuropathy mouse models

Abstract Hereditary optic neuropathies (HON), including dominant optic atrophy and Leber's hereditary optic neuropathy, are genetic disorders characterized by retinal ganglion cell (RGC) degeneration leading to vision loss, mainly associated with mitochondrial dysfunction. In this study, we analyzed mitochondrial distribution and ultrastructure in the retina and longitudinal optic nerve sections of presymptomatic HON mouse models with Opa1 and Nd6 deficiency to identify early mitochondrial changes. Our results show significant mitochondrial fragmentation and increased mitophagy in Opa1+/- mice, indicating early mitochondrial changes prior to neuronal loss. Conversely Nd6P25L mice exhibited mitochondrial hypertrophy, suggesting an adaptive response to compensate for altered energy metabolism. These pre-symptomatic mitochondrial changes were mainly observed in the unmyelinated portion of the RGC axons, where the transmission of the visual information requires high energy expenditure, constituting the specific point of vulnerability in HON. These findings highlight early focal mitochondrial changes prior to neuronal loss in HON and provide insight into presymptomatic therapeutic approaches.

The impact of research and development on the economies of countries of the world: A statistical analysis

Effective management of national science and research is on the constant rise, so the task of revealing how economic “return” from the research and development sector can be maximized is becoming more and more relevant. The article examines the mutual influence of the development of science and the funding of research and development in 97 countries around the world, on the one hand, and their national per capita incomes, on the other hand. A wide range of indicators is used, including patent activity, research and development expenditures, the number of researchers and the number of Scopus-indexed publications by subject area (relative to the population of countries). Among all the subject areas studied, the number of publications in economics is most closely related to the level of GDP per capita (PPP). We then use linear multiple regression to study the relation between the number of Scopus-indexed publications in economics and expenditures on research and development. A comparison of simulated data with real data shows that oil and gas producing countries (including Russia) demonstrate an economic level higher than expected. The leading world economies (USA, China, Japan, Germany, France, Great Britain) are well described by our resulting model. Ensuring high expenditure on research and development is of paramount importance for modern economic growth. In addition, an overall high level of publication activity is important, with particular attention to the development of research in economics.

Communication in the Era of Media Convergence and Tourism Enhancement in Samut Songkhram Province Based on the Digital Economy

This qualitative research aims to explore the problems and obstacles of communication in the era of media convergence for tourism promotion and the ability to enhance tourism in Samut Songkhram Province based on the digital economy. An in-depth interview was used to collect data from 27 people: Samut Songkhram representatives or community leaders, tourists, and communication and tourism scholars. The data was analyzed by content analysis and interpretation to present a descriptive narrative. The findings revealed that problems and obstacles to communication in the era of media convergence include the need for a more concise communication process in tourism. Many steps in coordinating cause inconvenience and slowness, which is considered a high cost and expenditure for communication in tourism. As for communication, the era of media convergence and the ability to enhance the provincial tourism of Samut Songkhram based on the digital economy, the respondents thought that they should use integrated communication that combines all platform media to foster innovation in development and support the economy from the grass root which creates and distributes income to residents in Samut Songkhram community. They should develop technological skills and creativity to achieve excellence so the community can adapt to the current and future changes. In this regard, the discussion revealed interesting information that communication in the era of media convergence, where content is delivered across multiple platforms simultaneously, can be used as a guideline to elevate Samut Songkhram tourism with the concept of "Digital Economy Creative Tourism," which Samut Songkhram communities must adjust to keep up with changes that occur all the time.

ANALYSIS OF THE DEGREE OF FISCAL DECENTRALISATION, INDEPENDENCE, REVENUE EFFECTIVENESS, AND FINANCIAL EFFICIENCY IN MEASURING FINANCIAL PERFORMANCE

This research aims to analyze the factors causing the Degree of Fiscal Decentralization Ratio to remain at an adequate level, the Independence Ratio to be relatively high, the Regional Budget Revenue Effectiveness Ratio to be high, and the Regional Financial Efficiency Ratio to also be high. Additionally, the study seeks to improve the financial performance of the Riau Islands Provincial Government based on these ratios. This field research uses a quantitative descriptive approach, collecting data from the Riau Islands Provincial Financial and Asset Management Agency’s Budget Realization Report with a saturated sampling technique. The results show that the Degree of Decentralization Ratio remains within sufficient criteria, the Independence Ratio is at a medium level, the Regional Budget Revenue Effectiveness Ratio is already very effective, while the Regional Financial Efficiency Ratio is inefficient. To improve financial performance concerning the Independence Ratio, it is recommended to provide public education on natural resource management. For the Decentralization Ratio, efforts are needed to develop trade and manufacturing sectors and optimize existing Regional Budget Revenues. To enhance the Effectiveness Ratio, it is important to continue optimizing regional income utilization, and for the Efficiency Ratio, preparing regional workers according to their fields is essential to reduce the relatively high regional expenditures.

Levels of IL-6 and IL-8 in complicated versus uncomplicated urinary tract infection

Background: Urinary tract infections (UTIs) are one of the world's most frequent infectious diseases, affecting 150 million people each year and resulting in severe morbidity and high medical expenditures. UTIs can be clinically defined as uncomplicated UTIs (uUTIs) or complicated UTIs (cUTIs) to differentiate infections of benign origin from those with a higher risk of recurrence or progression to severe pathology. The aim of this study was to evaluate interleukin-6 (IL-6) and IL-8 as potential biomarkers in differentiating complicated and uncomplicated Methods: Ninety samples of urine were collected. There were 43 samples from healthy controls and 47 samples from UTI patients, those who have been clinically diagnosed with UTIs by the urologist. The serum IL-6 and IL-8 were measured using an enzyme-linked immunosorbent assay and commercially available kits. Results: The levels of both IL-6 and IL-8 were significantly higher in UTI patient then in control subjects (p=0.001, p=0.001). A significant difference was observed in the mean of level IL-6 between culture positive UTI patients and culture negative UTI patients (p=0.014). In addition, the type of bacterial growth, a significant difference was observed in the mean of serum IL-6 and IL-8 level in UTI caused by gram negative bacteria in comparison with UTI caused by gram positive bacteria. Conclusion: High levels of IL-6 are associated with the growth of gram-negative bacteria, and this indicates that gram-negative bacteria could induce stronger inflammatory responses than gram-positive bacteria. IL-8 levels are higher in UTIs caused by gram-negative bacteria. This result further supported the evidence that gram-negative bacteria are potent inducers of inflammatory responses.

Sex-specific guideline target value attainment and prognostic value of low-density lipoprotein cholesterol in tertiary care

Abstract Background Factors contributing to guideline-target-level-attainment of low-density lipoprotein cholesterol (LDL-C) in countries with high healthcare expenditure are incompletely understood. Purpose the primary aim of this study was to test two hypotheses: 1) LDL-C control may be inferior in women versus men; 2) within the secondary prevention group, presence of a previous acute atherothrombotic event (acute myocardial infarction and stroke) may result in superior LDL-C control. Methods LDL-C levels and guideline target level attainment were determined in 4090 consecutive patients referred for myocardial perfusion single photon emission tomography (MPI-SPECT) between 2010 and 2016. Findings were validated in an independent cohort (n=1228) of consecutively enrolled patients in an outpatient cardiac rehabilitation program, between 2016 and 2023. Results About one third of patients (33%) were women, median age was 68 years, 1439 patients had a history of atherothrombosis, 759 patients a history of atherosclerosis without atherothrombosis, and 1892 were in primary prevention. LDL-C levels were higher and guideline target level attainment worse in women than in men in all three strata: age-adjusted difference in atherothrombosis 0.19 mmol/L (95%CI 0.03,0.35 mmol), guideline-target-value-attainment 39.5 % versus 49.4%, p<0.01; in atherosclerosis 0.33 mmol/L (95%CI 0.10-0.57), guideline-target-value-attainment 27.3 % versus 42.2 %, p<0.01; and in primary prevention 0.24 mmol/L (95% CI 0.13-0.38). This was confirmed in the validation cohort. LDL-C levels were higher and guideline-target-value-attainment worse in women versus men: age-adjusted difference age-adjusted difference 0.17 mmol/L (95%CI 0.02-0.33) guideline-target-value-attainment 43.8% versus 49.5%, After multivariate adjustment, female sex remained an independent predictor for higher LDL-C levels. LDL-C concentrations with atherothrombosis was 1.93 mmol/L (IQR 1.48-2.47) versus 2.07 mmol/L (IQR 1.40-2.72, p=0.003) with atherosclerosis and guideline target value attainment 47.5% vs 38.6%, p<0.001, respectively. Conclusion Concerning age-adjusted sex-inequalities with higher LDL-C levels and lower guideline-target-value-attainment in women were found in both primary and secondary prevention. Within secondary prevention, a previous atherothrombotic event was associated with lower LDL-C levels and higher guideline-target-value-attainment.

An analytical approach for evaluation of conveyor exit strategies in open-pit mines

Transportation is the most expensive task in deep open-pit mining operations. An In-Pit Crushing and Conveying (IPCC) system, as an alternative to the conventional shovel-truck system, requires precise planning to avoid wasting high capital expenditures on trucks. The decision to fit a conveyor system into the pit design is challenging and needs to be addressed in the literature. Further optimisation of the IPCC system requires choosing an appropriate conveyor exit strategy. Conveyor exit schemes include a Dedicated Ramp Slot (DRS), an Existing Ramping System, an inclined tunnel and High-Angle Conveyors (HAC). This paper provides an analytical approach to compare the cost of different conveyor exit strategies in open-pit mines. The results indicate that for a depth up to 100 m, the Present Value of Cost (PVC) for the DRS is the least. For the cases deeper than 300 m, the HAC has the least PVC. Sensitivity analysis showed that for the depths between 100 and 300 m, a more accurate and detailed definition of parameters is needed. Besides, in most cases, the HAC provides the lowest payback period and the highest internal rate of return among the alternatives.

Effect of government's environmental attention on corporate philanthropy based on the institutional theory: Evidence from China's heavily polluting companies.

The underlying motivation behind corporate philanthropy (CP) is subject to multiple interpretations. For emerging markets, traditional interpretations based on a perspective of interest exchange often fall short. The institutional environment in China is characterized by uncertainty, particularly in the field of environmental protection, where the government's attention, a scarce institutional resource, can influence the behaviors of heavily polluting companies. The government's environmental attention (GEA) may be subject to campaign-style investment, which provides an opportunity for research. This study attempts to use institutional theory to construct a difference-in-differences model using the Central Inspection of Environmental Protection as an exogenous shock. It examines the causal impact of GEA on CP, observing that GEA has a positive effect on CP, especially for large companies, companies in less competitive industries, companies located in high-pollution areas, and companies with high environmental expenditure. The results indicate that campaign-style institutional changes provide a non-transactional political motivation for CP. In addition, we discuss the mechanism, which is the expectation change. Campaign-style institutional changes work by altering corporations' expectations of the future institutional environment. We verify this mechanism from two perspectives, namely, the intensity of changes caused by uncertainty and corporate sensitivity to changes. Our results remain robust when subject to several tests based on different identification hypotheses and alternative measures. Unlike the existing literature on the political connections driving CP in China, this study, based on the institutional theory framework, reveals that campaign-style institutional changes constitute a non-transactional, unidirectional political motivation, which is a significant driving factor for CP in a Chinese context. This study evaluates the importance of GEA and reveals the non-transactional political motivations from the institutional theory perspective. This not only enriches existing discussions on the political motivations of CP but also broadens our understanding of the relationship between institutional uncertainty and CP in emerging markets.

The Impact of Closing Medicare Part D Coverage Gap on Mental Health of Adults Over Age 65.

Using Medical Expenditure Panel Survey data from 2006 to 2019, this study assessed the effect of closing Medicare Part D coverage gap on mental health of older adults. We employed difference-in-differences and compared mental health outcomes of older adults on Medicare with those on private insurance before and after the 2011 policy change. Findings showed a 0.447-point reduction in the Kessler Index 6 (K-6) score after closure. These findings were mainly attributable to women, Hispanics, individuals with multiple chronic conditions, and those in Traditional Medicare. A reduction in out-of-pocket (OOP) expenditures appeared to be the primary mechanism for this finding. Our analysis was robust to several specifications, including using different measures of mental health and alternate constructions of treatment and control groups. The closure of the Medicare Part D coverage gap improved mental health among beneficiaries, potentially by reducing financial strain associated with high OOP expenditures.

A stableness of resistance model for nonresponse adjustment with callback data

Abstract Nonresponse arises frequently in surveys, and follow-ups are routinely made to increase the response rate. In order to monitor the follow-up process, callback data have been used in social sciences and survey studies for decades. In modern surveys, the availability of callback data is increasing because the response rate is decreasing, and follow-ups are essential to collect maximum information. Although callback data are helpful to reduce the bias in surveys, such data have not been widely used in statistical analysis until recently. We propose a stableness of resistance assumption for nonresponse adjustment with callback data. We establish the identification and the semiparametric efficiency theory under this assumption, and propose a suite of semiparametric estimation methods including doubly robust estimators, which generalize existing parametric approaches for callback data analysis. We apply the approach to a Consumer Expenditure Survey dataset. The results suggest an association between nonresponse and high housing expenditures.

Financing green innovation startups: a systematic literature review on early-stage SME funding

ABSTRACT This paper investigates the critical issue of financing early-stage green startups, examining the types of investors and finance models available, the challenges these startups face, and how the green finance ecosystem can better support early-stage investment. Utilizing a systematic literature review (SLR) methodology, we provide a comprehensive analysis of the current landscape. Our findings reveal a significant paucity of data and a bias towards well-established North American and European ecosystems, while highlighting an emerging diversity in private finance sources post-Global financial crisis (GFC), including grants, equity, and crowdfunding. Despite this, there remains a heavy reliance on public funding and a lack of evidence regarding its impact. The inherent characteristics of cleantech – high capital expenditure, long investment horizons, and disruptive nature – necessitate innovative public financing instruments and policies to reduce risk and attract private investment. Our theoretical contribution highlights the necessity for interdisciplinary research and policy collaboration to develop a holistic entrepreneurial finance (entfin) ecosystem. This approach should integrate quantitative economic and qualitative behavioural finance research to address information asymmetries and improve the green economy policy mix. Such a framework will support public-private co-financing, enhance stakeholder engagement, and provide evidence for policy decisions, facilitating more rapid commercialization of cleantech innovations for environmental sustainability.

Stocking density affects growth, feed utilisation, metabolism, welfare and associated mRNA transcripts in liver and muscle of rainbow trout more pronouncedly than dietary fish meal inclusion level

In aquaculture, stocking density and diet composition are critical factors that influence the performance and welfare of the farmed animal. However, there is limited information on their interactive effects. In this context, applying a 2 × 2 factorial design, we conducted a 12-week feeding trial to evaluate the effect of stocking density (low, LSD: 3.3–15 kg m−3 and high, HSD: 5.8–25 kg m−3; initial-final values) and dietary fish meal content (high, HFM: 30 % and low, LFM: 15 %) on growth, feed utilisation, metabolic oxygen consumption, tissue indices, carcass composition, plasma metabolites, and transcriptional regulation of growth, metabolism and welfare-related biomarker mRNAs in liver and muscle of the juvenile rainbow trout. At the whole-animal level, the HSD group showed significantly higher routine metabolic rate and feed intake indicating higher energy demand; but growth and feed efficiency was lower in HSD than the LSD group. Morpho-anatomically, HSD fish had lower relative gut length and higher intra-peritoneal fat index than LSD fish. Lower plasma free amino acids and glucose levels reiterated high energy expenditure in HSD, and elevated albumin levels indicated potential oxidative stress in the HSD group. Correspondingly, at the transcriptional level, hepatic mRNA levels of antioxidative enzymes (sod, cat, gst, g6pd) and stress-related molecular chaperone hsp90 were up-regulated in HSD; while the transcript abundance of growth-axis markers (ghr, igf1 igf2) and nutrient-sensor mtor were decreased. In muscle, proteolytic pathway components fbx32 and murf1 were upregulated in HSD, and concurrently mtor was also upregulated suggesting higher protein turnover in this group. With respect to the effect of dietary fish meal inclusion levels, LFM showed decrease in growth, hepatic igf2 expression, and lower plasma triglycerides and free amino acid levels than HFM group. However, the sensory appearance of flesh was found to be slightly better in LFM. Significant diet-husbandry interactions were not observed phenotypically, but the mRNA abundance of hepatic markers (ampk1, hsp70, mhc1 and tnfa) linked to energy-sensing, stress and immune response were differentially regulated. Overall, the study shows that high stocking density has a greater degree of impact on fish growth and welfare than reduction in dietary fishmeal inclusion, with limited interactional effects.

Healthcare expenditures among older immigrants in the US with Alzheimer's disease and related dementias: Population-based study between 2007 and 2020.

Using nationally representative datasets, this study examined differences in healthcare expenditures between US-born and foreign-born individuals aged 65 and above by the presence of Alzheimer's disease and related dementias (ADRD) and cognitive limitations (CL). This study further examined whether healthcare expenditures among foreign-born individuals vary by their duration of residence in the US. The study used the 2007-2020 Medical Expenditure Panel Survey (MEPS) and employed generalized linear regression models to estimate differences in healthcare expenditures between US-born and foreign-born older adults with ADRD, CL, and without ADRD or CL. Survey weights were applied to all estimates. Our study identified significant differences in healthcare expenditures among older adults by the presence of ADRD/CL and immigrant status. Having ADRD/CL had a more pronounced impact on high healthcare expenditures among foreign-born older adults than US-born adults with ADRD/CL, thereby diminishing the difference in healthcare expenditures by US nativity status for the older adults with ADRD or CL. In the analysis further distinguishing immigrants by their duration of residence, lower healthcare expenditures were primarily observed among foreign-born individuals with ADRD or CL who had lived in the US for less than ten years. Our results suggest potential shifts in costs resulting from delayed access to, and diagnosis or treatment of ADRD at a younger age, leading to increased healthcare needs and expenses among US foreign-born older adults.

Alcohol culture and employee treatment

This paper examines the impact of corporate alcohol culture on employee treatment, and find that a rich corporate alcohol culture atmosphere is negative significantly associated with employee treatment. Mechanistically, the corporate alcohol culture increases the aggressiveness motivation of management, in turn increasing risk taking and management overconfidence. Furthermore, the corporate alcohol culture extends managing external social network rather than developing interpersonal relationships, which causes management to less focus on protecting employees' rights and interests. Notably, the inhibitory impact of corporate alcohol culture on employee treatment is particularly pronounced in non-state-owned enterprises (non-SOEs), male-dominated industries, and firms with high entertainment expenditure rates. These insights underscore the nuanced dynamics of alcohol culture within corporate settings and its implications for employee welfare and organizational behavior.

Risk factors for early readmission to hospital in patients with malignancy-related ascites: a retrospective cohort study.

Malignancy-related ascites (MRA) is a common serious complication of many advanced malignant tumors with high morbidity and mortality. The high hospital expenditures induced by unplanned readmission in patients with MRA have become an urgent issue to the public. We aimed to overall assess the unplanned early readmission rate of patients with MRA and explore the potential risk factors for such readmission. A retrospective cohort study based on 2018 Nationwide Readmissions Database was performed and patients with MRA were recruited into the analysis. The primary outcome was unplanned 30-day readmission rate and inpatient outcomes. The multivariate logistic regression analysis was performed to evaluate the potential risk factors for such early readmission. Data obtained from 32,457 patients with MRA were analyzed, and of these 7,799 individuals (24.03%) were unplanned readmitted within 30-day follow-up. The mortality rate in the readmitted population was 15.15%. Patients at younger age were at a higher risk of readmission. The morbidities including hypertension (OR=1.117, 95%CI: 1.054-1.184), hyperlipemia (OR=1.075, 95%CI: 1.009-1.146) and diabetes (OR=1.118, 95%CI: 1.053-1.188), gastrointestinal malignancies and peritoneal procedure significantly increased the risk of 30-day readmission in patients with MRA. More than one in five patients with MRA was unplanned readmitted within 30-day follow-up. The above risk factors should be timely intervened and the corresponding medical care should be strengthened in patients with MRA to lessen the unplanned readmission and improve the readmission outcomes.

Predictors of Utilization Frequency of and Expenditure Amount for Chiropractic Care in U.S. Adults: A Retrospective Cohort Study

ObjectiveThis study aimed to evaluate the prospective associations of baseline personal characteristics with utilization frequency and expenditure of chiropractic care in US adults (≥18 years). MethodsData are from the 1358 respondents to the 2014 to 2016 Medical Expenditure Panel Survey who utilized chiropractic care. Individual, familial, health-related, and behavioral factors were included as covariates in the multivariate analytic model. Poisson and multinominal logistic regressions were modeled to examine the associations between the predictors and chiropractic utilization and expenditure. ResultsThe mean annual number of visits was 8.2 visits (95% confidence interval [CI]: 7.9, 8.5), with annual expenditure of $677.43 U.S. dollars (95% CI: $595.47-$759.39) and $84.84 (95% CI: $77.89-$91.78) per visit. Female sex was associated with a 19% higher number of visits (rate ratio [RR] = 1.19, 95% CI: 1.01, 1.41) than males. Publicly insured and uninsured were associated with a 44% higher (RR = 1.44, 95% CI: 1.14, 1.82) and 36% lower (RR = 0.64, 95% CI: 0.48, 0.86) visit frequency, respectively, than those privately insured. Rheumatoid arthritis was associated with 7.38 times the risk of high expenditure (95% CI: 2.61, 24.67) than medium expenditure, compared to no arthritis. Relative to physically active individuals, physical inactivity was associated with a 27% higher visit frequency (RR = 1.27, 95% CI: 1.09, 1.49) and an 82% higher risk (relative risk ratio = 1.82, 95% CI: 1.05, 3.14) of high expenditure than low expenditure. ConclusionThis analysis found distinct usage and expenditure patterns that vary according to specific baseline predictors. Female sex, being publicly insured, having rheumatoid arthritis, and physically inactive were associated with variance in expenditure. Results from this study may help identify chiropractic patients with tendencies for higher utilization or spending and may indirectly assist in predicting patients with slower response to care.

The Relationship of Pain Intensity, Perceived Injustice, and Pain Catastrophizing to Heart Rate Variability In Naturally Occurring Acute Pain.

Chronic pain disorders are among the most common and affect approximately 20% of the US population, leading to disproportionately high medical expenditures and negative economic impact. Behavioral factors of pain catastrophizing and perceived injustice are associated with pain intensity in chronic pain. Diminished heart rate variability (HRV) is also strongly associated with chronic pain. These factors have been less explored earlier in the pain experience and it is unclear whether they play a role in the transition from acute to chronic pain. The aim of this study was to determine the relationship between pain catastrophizing, perceived injustice, pain intensity and HRV in naturally occurring acute pain. Ninety-seven subjects were recruited from local outpatient physical therapy clinics. Seated HRV was captured on ninety-four subjects via Polar chest strap while subjects were taking a survey via iPad. In addition to sociodemographic data, the survey included the Pain Catastrophizing Scale (PCS), Injustice Experience Questionnaire (IEQ), and Numeric Pain Rating Scale (NPRS). The natural log of high frequency power (lnHFP) HRV was used in the statistical analysis. Multiple regression modeling revealed that lower pain catastrophizing, higher perceived injustice, and lower pain intensity were associated with lower HRV, and accounted for 11.4% of the variance in HRV. While greater chronic pain intensity is associated with lower HRV, the relationship is reversed in the setting of acute pain. These findings highlight the need to better understand the unique factors that contribute to lower HRV in the acute phase.

Inferring the metabolic rate of bone

The bone organ is poorly represented in comparative research on mammalian mass-specific metabolic rates. As a first order attempt to remedy this, from the literature we collected mass-specific metabolic rates for all major organs except for the bone organ, and by subtraction infer the rate for the bone organ. The scaling relationships are given of each whole-organ mass-specific metabolic rate and of the relationship between whole-organ metabolic rate and body mass. Scaling of the lung, adipose depot and bone organ with body mass is higher than would be expected by ¾ power scaling. We interpret the similar scalings of bone and the adipose depot in light of their evolved regulation of whole-body metabolism. We also briefly examine the supra-¾ power scaling of the lung as well as the independence of the mass-specific metabolic rate of the heart from body mass. The bone organ exhibits relatively high energy expenditure with increasing body size. The bone marrow and its medullary adipocyte store may be responsible for engendering the greater share of the bone organ's energetic cost.

External Mechanical Work Versus Energy Expenditure During on-Court Tennis Drills in Elite Adolescent Tennis Players

Abstract Purpose Tennis demands exceptional technical skills, speed, strength and endurance. Previous studies have highlighted the high energy expenditure during tennis drills due to constant directional changes. While metabolic monitoring and player tracking have been used to quantify exercise intensity and movements, mechanical efficiency (ME) in tennis remains poorly understood. This study aimed to investigate ME in tennis by combining metabolic and mechanical measurements during on-court drills. Methods Ten elite adolescent tennis players (males n = 5, females n = 5) performed a VO2max test on a treadmill and participated in three standard tennis drills, Spanish cross, lateral and inside out. During the tennis drill, full-body kinematics were captured, and energy expenditure was measured using a portable breath-by-breath gas analysis. ME was calculated for each drill, and individual differences were examined. Results Results revealed significant differences in energy expenditure and mechanical work between drills. ME was not associated with VO2max or running speed. highlighting the need to focus on other factors like strength, footwork technique, and neuromuscular training to enhance ME. Conclusion This study underscores the complexity of ME in tennis, with individual variations and where factors like footwork technique, muscular strength and motor abilities might influence ME.

Electrical-Modulated Flexible Acoustic Metamaterial: Enhancing Low-Frequency Absorption via an Ionic Electroactive Polymer.

The growing concern over low-frequency noise pollution resulting from global industrialization has posed substantial challenges in noise attenuation. However, conventional acoustic metamaterials, with fixed geometries, offer limited flexibility in the frequency range adjustment once constructed. This research unveiled the promising potential of ionic electroactive polymers, particularly ionic polymer-metal composites (IPMCs), as a superior candidate to design tunable acoustic metamaterial due to its bidirectional energy conversion capabilities. The previously perceived limitations of the IPMC, including slow reaction and high energy expenditure, owning to its inherent sluggish intermediary ionic mass transport process, were astutely leveraged to expedite the attenuation of low-frequency sound energy. Both our experimental and simulation results elucidated that the IPMC can generate voltage potentials in response to acoustic pressure at frequencies significantly higher than those previously established. In addition, the peak absorption frequency can be effectively shifted by up to 45.7% with the application of a 4 V voltage. By further integration with a microperforated panel (MPP) structure, the developed metamaterial absorbers can achieve complete sound absorption, which was continuously tunable under minimal voltage stimulation across a wide frequency spectrum. In addition, a microslit structure IPMC metamaterial absorber was designed to realize modulation of the perforation rate, and the absorption peak can be shifted by up to 79.2%. These findings signify a pioneering application of ionic intelligent materials and may pave the way for further innovations of tunable low-frequency acoustic structures, ultimately advancing the pragmatic deployment of both soft intelligent materials and acoustic metamaterials.