Estimating price elasticities of demand for pain relief drugs: evidence from Medicare Part D.

Overdose deaths from prescription opioids remain elevated, and policymakers seek solutions to curb opioid misuse. Recent proposals call for price-based solutions, such as opioid taxes and removal of opioids from insurance formularies. However, there is limited evidence on how opioid consumption responds to price stimuli. This study addresses that gap by estimating the effects of prices on the utilization of opioids, as well as other prescription painkillers. I use nationally representative individual-level data on prescription drug purchases and exploit the introduction of Medicare Part D in 2006 as an exogenous change in out-of-pocket drug prices. I find that new users have a relatively high price elasticity of demand for prescription opioids, and that consumers treat over-the-counter painkillers as substitutes for prescription painkillers. My results suggest that increasing out-of-pocket prices of opioids, through formulary design or taxes, may be effective in reducing new opioid use.

Food Cue Reactivity Meets the Reinforcer Pathology Model: Behavioral Economic Measures of Cue-Induced Changes in Food Reinforcer Efficacy.

Food cue reactivity, or behavioral sensitivity to conditioned food cues, is an eating pattern observed in those with obesity and binge-eating disorder. The reinforcer pathology model, which characterizes overconsumption of a reinforcer such as food may be relevant to food cue reactivity, especially in those with obesity and binge-eating disorder. The reinforcer pathology model posits that steep delay discounting (DD) and demand elasticity are processes involved in the overconsumption of food. Two of our recent studies examine the extent to which reactivity to conditioned food cues may be involved in food reinforcer pathologies. First, food cues were conditioned with Oreo cookies with binge-eating prone (BEP) and binge-eating resistant (BER) rats. Delay discounting was compared before and after conditioning. Food cues induced steeper DD for rats, though BEP rats showed some evidence for greater sensitivity to this effect than BER rats, albeit this difference was not significant. Second, healthy-weight humans and humans with overweight/obese BMI underwent conditioning of visual cues paired with M&M candies. After acquisition, cues induced greater demand intensity and inelasticity for food compared to baseline. Participants with overweight/obese BMI, compared to controls, also showed some evidence for greater sensitivity to this change ininelasticity compared to healthy-weight participants, but this difference was also not significant. Food cues, then, may induce changes in DD and economic demand, supporting the relevance of reinforcer pathologies.

Dynamics of a goshawk population across half a century is driven by the variation of first-year survival.

Population dynamics are driven by stochastic and density-dependent processes acting on demographic rates. Individuals differ demographically, and to capture these differences, models of population dynamics are usually structured by age and stage, rarely by sex. An effect of sex on population dynamics is expected if the dynamics of males and females differ, requiring an unequal sex ratio at birth and/or sex-specific survival probabilities. Goshawks (Accipiter gentilis) show large sexual size dimorphism and differential survival, but it is unknown whether males and females contribute differently to population dynamics. We studied a goshawk population in northern Germany over 47 years using brood monitoring data, collected feathers and nestling ringing data. We jointly analyzed the data using a two-sex integrated population model and performed retrospective and prospective population analyses to understand whether the demographic drivers of population change differ between the sexes. The population showed large fluctuations, during which the number of breeding pairs doubled, but the long-term trend of the population was slightly negative. Female survival exceeded male survival during the first year of life. Females started to reproduce at a younger age than males, productivity increased with female age, the sex ratio of nestlings was male biased and there was moderate male immigration. Despite these differences, temporal variation in sex ratio did not contribute to population dynamics and the contribution of temporal variation in survival was similar for both sexes. Variation in first-year survival was the strongest driver in this population, regulated by a weak density-dependent feedback acting through female first-year survival. Overall, the contributions of the two sexes to population dynamics were similar in this monogamous species with strong sexual size dimorphism.

Breast multiparametric ultrasound: a single-center experience.

PURPOSE: To evaluate the role of multiparametric ultrasound (mpUS) in the characterization of focal breast lesions (FBLs). METHODS: This prospective study enrolled patients undergoing multiparametric breast ultrasound for FBLs. An experienced breast radiologist evaluated the following ultrasound features: US BI-RADS category, vascularization pattern (internal, vessels in rim and combined) and presence of penetrating vessels with each Doppler method (Color-Doppler, Power-Doppler, Microvascular imaging), strain ratio (SR) and Tsukuba score (TS) with Strain Elastography (SE), Emax, Emean, Emin and Eratio with 2D-shear wave elastography (2D-SWE). Core biopsy for all BI-RADS 4-5 FBLs and 24-month follow-up for all BI-RADS 2-3 FBLs were considered for standard of reference. The diagnostic performance was assessed with the area under curve (AUCs) and cut-off values were determined according to the Youden's index. RESULTS: A total of 139 FBLs were included with 75/139 (53.9%) benign and 64/139 (46.1%) malignant FBLs. Internal vascularization patterns (p < 0.001), penetrating vessels (p < 0.001), TS 4-5 (p < 0.001) and all 2D-SWE parameters (p < 0.001) were significantly different between benign and malignant FBLs. The BI-RADS score provided an AUC of 0.876 (95% CI 0.810-0.926) for the diagnosis of malignant FBLs. Among the 2D-SWE measurements, an excellent diagnostic performance was observed for Emax with an AUC of 0.915 (95% CI 0.856-0.956) and Emean of 0.908 (95% CI 0.847-0.951). Optimal cutoff for the diagnosis of malignant FBLs were US BI-RADS > 3, Strain Ratio > 2.52, Tsukuba Score > 3, Emax > 82.6 kPa, Emean > 66.0 kPa, Emin > 54.4 kPa and Eratio > 330.8. Multiparametric ultrasound, particularly SWE, can improve specificity in the characterization of FBLs.

Water relations and photosystem II efficiency of the intertidal macroalga Fucus virsoides.

Intertidal macroalgae are sessile poikilohydric organisms exposed to desiccation stress during emersion. Water relations parameters are useful tools to evaluate an organism's capacity to withstand water scarcity conditions, but such information on marine intertidal macroalgae is scarce. We assessed the water relations of the intertidal relict Fucus virsoides, the unique Fucus species endemic to the Mediterranean. We combined measurements of water potential (Ψ) parameters derived from pressure-volume curves and chlorophyll a fluorescence (Fv/Fm) in juvenile and adult thalli sampled in three different dates between March and April 2023. F. virsoides exhibited remarkable water stress tolerance, as evidenced by the low water potential at turgor loss point (Ψtlp, -7.0 MPa on average), and the maintenance of high Fv/Fm at low water potentials indicating a prolonged maintenance of healthy physiological status. While no differences were observed between growth stages, Ψtlp, capacitance (C) and the bulk modulus of elasticity (ε) varied significantly according to the sampling dates, whereas the osmotic potential at full turgor did not significantly change. Ψ measured on thalli collected after a typical prolonged emersion period was markedly lower (-12.3 MPa on average) than the estimated Ψtlp, suggesting that the population is frequently undergoing turgor loss. Further investigations are required to determine environmental tolerance ranges based on water status characteristics to enhance our understanding of F. virsoides responses and vulnerability to climate change, thus providing insight into the possible causes of its widespread decline.

Shear-wave elastographic imaging in choroidal melanomas: clinical and hemodynamic correlations.

PURPOSE: This study evaluated the role of shear wave elastography imaging (SWEΙ) in uveal melanomas and the associations between SWEI and clinical and hemodynamic findings. STUDY DESIGN: Prospective, clinical study METHODS: Twelve patients with uveal melanomas, scheduled to undergo Ru-106 brachytherapy, were prospectively recruited from the Department of Ophthalmology of the University Hospital of Heraklion (September-December 2022). B-mode, hemodynamic and SWEI ultrasonography examinations were performed with the HiScan (OPTIKON 2000) and the LOGIQ E9 (GE Healthcare) sonographic systems, respectively. Differences in SWEI scores (kPa) between tumor (TS) and adjacent non-affected choroid (CS), as well as between TS and orbital fat (FS) were examined. Correlations between SWEI and intra-tumoral hemodynamic parameters, including peak systolic and end diastolic velocities and resistivity index (RI) were also examined. RESULTS: TS was significantly correlated with intra-tumoral RI (Pearson's bivariate correlation coefficient 0.681, p=0.015) and with maximal tumor height (Pearson's bivariate correlation coefficient 0.620, p=0.031). TS was significantly higher than both FS and CS scores (paired-samples t-test, p=0.003 and p=0.006, respectively). CONCLUSIONS: SWEI score is applicable as a quantitative biomechanical marker in the assessment of choroidal melanoma. Choroidal melanomas are stiffer than both adjacent choroid and orbital fat. Moreover, choroidal melanomas with higher RI as well as those with higher apical elevations display higher SWEI scores.

The elasticity of silicone-stabilized liposomes has no impact on their in vivo behavior.

BACKGROUND: The elastomechanical properties of nanocarriers have recently been discussed as important for the efficient delivery of various therapeutics. Some data indicate that optimal nanocarriers' elasticity can modulate in vivo nanocarrier stability, interaction with phagocytes, and uptake by target cells. Here, we presented a study to extensively analyze the in vivo behavior of LIP-SS liposomes that were modified by forming the silicone network within the lipid bilayers to improve their elastomechanical properties. We verified liposome pharmacokinetic profiles and biodistribution, including retention in tumors on a mouse model of breast cancer, while biocompatibility was analyzed on healthy mice. RESULTS: We showed that fluorescently labeled LIP-SS and control LIP-CAT liposomes had similar pharmacokinetic profiles, biodistribution, and retention in tumors, indicating that modified elasticity did not improve nanocarrier in vivo performance. Interestingly, biocompatibility studies revealed no changes in blood morphology, liver, spleen, and kidney function but indicated prolonged activation of immune response manifesting in increased concentration of proinflammatory cytokines in sera of animals exposed to all tested liposomes. CONCLUSION: Incorporating the silicone layer into the liposome structure did not change nanocarriers' characteristics in vivo. Further modification of the LIP-SS surface, including decoration with hydrophilic stealth polymers, should be performed to improve their pharmacokinetics and retention in tumors significantly. Activation of the immune response by LIP-SS and LIP-CAT, resulting in elevated inflammatory cytokine production, requires detailed studies to elucidate its mechanism.

Modulating Elasticity of Liposome for Enhanced Cancer Immunotherapy.

Cancer immunotherapy has emerged as a promising approach to cancer treatment in recent years. The physical and chemical properties of nanocarriers are critical factors that regulate the immune activation of antigen-presenting cells (APCs) in the tumor microenvironment (TME). Herein, we extensively investigated the behavior of liposome nanoparticles (Lipo-NPs) with different elasticities, focusing on their interaction with immune cells and their transport mechanisms from tumors to tumor-draining lymph nodes (tdLNs). Successfully preparing Lipo-NPs with distinct elastic properties, their varied behaviors were observed, concerning immune cell interaction. Soft Lipo-NPs exhibited an affinity to cell membranes, while those with medium elasticity facilitated the cargo delivery to macrophages through membrane fusion. Conversely, hard Lipo-NPs enter macrophages via classical cellular uptake pathways. Additionally, it was noted that softer Lipo-NPs displayed superior transport to tdLNs in vivo, attributed to their deformable nature with lower elasticity. As a result, the medium elastic Lipo-NPs with agonists (cGAMP), by activating the STING pathway and enhancing transport to tdLNs, promoted abundant infiltration of tumor-infiltrating lymphocytes (TILs), leading to notable antitumor effects and extended survival in a melanoma mouse model. Furthermore, this study highlighted the potential synergistic effect of medium elasticity Lipo-NPs with immune checkpoint blockade (ICB) therapy in preventing tumor immune evasion. These findings hold promise for guiding immune-targeted delivery systems in cancer immunotherapy, particularly in vaccine design for tdLNs targeting and eradicating metastasis within tdLNs.

Skin mechanical properties measured with skin elasticity measurement device in patients with lymphedema: Scoping review.

BACKGROUND: Skin conditions in patients with lymphedema have been identified according to changes in skin mechanical properties. The skin elasticity meter is a non-invasive tool for measuring the mechanical properties of the skin; however, its potential use in patients with lymphedema has received little attention. This review aimed to provide an overview of studies measuring the skin mechanical properties of patients with lymphedema using a skin elasticity meter. MATERIALS AND METHODS: Search terms and synonyms related to lymphedema and skin mechanical property measurement using a skin elasticity meter were identified, and electronic databases containing articles in English were searched. RESULTS: A total of 621 articles were retrieved, and four articles were analyzed after screening. Despite this research subject receiving increasing attention, no consensus has been reached regarding the best methods. CONCLUSION: Measurement methods are expected to be standardized in the future to elucidate the skin mechanical properties of patients with lymphedema.

Weight-specific normal liver stiffness values in children.

BACKGROUND: Two-dimensional (2-D) shear wave elastography is a commonly used sonographic elastography method for the noninvasive measurement of liver stiffness. There is little liver stiffness data available in the pediatric population and its association with the child's weight is scarce. OBJECTIVE: The principal aim of our study was to determine weight-specific reference liver stiffness values in a pediatric population free of liver disease. MATERIALS AND METHODS: In this retrospective single-center study, 2-D shear wave elastography values were recorded in children with no history of liver disease and with a clinically indicated ultrasound examination, between April 2021 and July 2022. Examinations were performed using an Aplio i800 and two Aplio a450 (Canon Medical Systems), with a convex probe (i8CX1 or 8C1 transducers). This population was divided into ten weight groups. We evaluated the relation between weight and liver elasticity values and compared right and left lobe measurements. RESULTS: During the period of the study, 235 children were included. We then excluded 64 patients (weight not available = 13, interquartile range to median ratio (IQR/M) greater than 30% = 51). On the final sample (171 patients, median age 6.5 years [0-18], median weight 22.6 kg [2.5-80]), stiffness values showed a global significant trend to increase with weight. In each group, there was no significant difference between right and left liver stiffness values. The mean normal liver stiffness value including all children was 5.3 ± 1.1 kPa. CONCLUSION: Liver stiffness in our pediatric sample with no history of liver disease increases with weight. These data may help to distinguish normal from pathological elastography values.

Usefulness of color Doppler and strain elastography adjunctive to B-mode ultrasonography in the diagnosis of non-mass abnormalities of the breast: results of the BC-07 multicenter study of 385 cases.

PURPOSE: The concept of non-mass abnormalities of the breast has been employed in Japan for approximately 20 years. Although B-mode findings are classified as non-mass abnormalities, the usefulness of adding color Doppler ultrasonography (US) and strain elastography to B-mode US is unclear. Therefore, we conducted a multicenter study (JABTS BC-07) to establish the diagnostic criteria for breast US, including color Doppler and elastography, for non-mass abnormalities of the breast and verify their diagnostic usefulness. METHODS: We registered US images of non-mass abnormalities of the breast and their clinical and histopathological data from 13 institutions (202 malignant and 183 benign non-mass lesions). Furthermore, we evaluated the centralized image interpretation usefulness of the diagnostic criteria for B-mode and color Doppler US, as well as the sensitivity and specificity when color Doppler US and elastography were added to B-mode US. RESULTS: Echogenic foci in the mammary gland (odds ratio 3.45, 95% confidence interval [CI] 1.92-6.19, p < 0.0001) and the configuration of internal solid components of the ducts (odds ratio 0.056, 95% CI 0.005-0.591, p < 0.0165) significantly differentiated benign and malignant non-mass abnormalities. The sensitivity of B-mode alone (83.7%) was significantly improved by adding color Doppler US (93.1%) (p = 0.0004); however, adding color Doppler US and elastography to B-mode US made no significant difference in either sensitivity or specificity. CONCLUSION: Although adding color Doppler US and elastography to B-mode US improved sensitivity, the diagnostic significance was limited. Therefore, a comprehensive diagnostic method comprising mammography and magnetic resonance imaging is warranted.

Elasticity Mapping of Colloidal Glasses Reveals the Interplay between Mesoscopic Order and Granular Mechanics.

Colloidal glasses (CGs) made of polymer (polymethylmethacrylate) nanoparticles are promising metamaterials for light and sound manipulation, but fabrication imperfections and fragility can limit their functionality and applications. Here, the vibrational mechanical modes of nanoparticles are probed to evaluate the nanomechanical and morphological properties of various CGs architectures. Utilizing the scanning micro-Brillouin light scattering (µ-BLS), the effective elastic constants and nanoparticles' sizes is determined as a function of position in a remote and non-destructive manner. This method is applied to CG mesostructures with different spatial distributions of their particle size and degree of order. These include CGs with single-sized systems, binary mixtures, bilayer structures, continuous gradient structures, and gradient mixtures. The microenvironments govern the local mechanical properties and highlight how the granular mesostructure can be used to develop durable functional polymer colloids. A size effect is revealed on the effective elastic constant, with the smallest particles and ordered assemblies forming robust structures, and classify the various types of mesoscale order in terms of their mechanical stiffness. The work establishes scanning µ-BLS as a tool for mapping elasticity, particle size, and local structure in complex nanostructures.

Comprehensive ultrasonographic evaluation of normal and fibrotic kidneys in a mouse model with an ultra-highfrequency transducer.

PURPOSE: This study aimed to establish baseline morphological and functional data for normal mouse kidneys via a clinical 33 MHz ultra-high-frequency (UHF) transducer, compare the data with the findings from fibrotic mice, and assess correlations between ultrasonography (US) parameters and fibrosis-related markers. METHODS: This retrospective study aggregated data from three separate experiments (obstructive nephropathy, diabetic nephropathy, and acute-to-chronic kidney injury models). Morphological parameters (kidney size, parenchymal thickness [PT]) and functional (shear-wave speed [SWS], stiffness, resistive index [RI], and microvascular imaging-derived vascular index [VI]) were assessed and compared between normal and fibrotic mouse kidneys. Semi-quantitative histopathologic scores were calculated and molecular markers (epithelial cadherin), Collagen 1A1 [Col1A1], transforming growth factor-ß, and α-smooth muscle actin [α-SMA]) were evaluated using western blots. Correlations with US parameters were explored. RESULTS: Clinical UHF US successfully imaged the kidneys of the experimental mice. A three-layer configuration was prevalent in the normal mouse kidney parenchyma (34/35) but was blurred in most fibrotic mouse kidneys (33/40). US parameters, including size (11.14 vs. 10.70 mm), PT (2.07 vs. 1.24 mm), RI (0.64 vs. 0.77), VI (22.55% vs. 11.47%, only for non-obstructive kidneys), SWS (1.67 vs. 2.06 m/s), and stiffness (8.23 vs. 12.92 kPa), showed significant differences between normal and fibrotic kidneys (P<0.001). These parameters also demonstrated strong discriminative ability in receiver operating characteristic curve analysis (area under the curve, 0.76 to 0.95; P<0.001). PT, VI, and RI were significantly correlated with histological fibrosis markers (ρ=-0.64 to -0.68 for PT and VI, ρ=0.71-0.76 for RI, P<0.001). VI exhibited strong negative correlations with Col1A1 (ρ=-0.76, P=0.006) and α-SMA (ρ=-0.75, P=0.009). CONCLUSION: Clinical UHF US effectively distinguished normal and fibrotic mouse kidneys, indicating the potential of US parameters, notably VI, as noninvasive markers for tracking fibrosis initiation and progression in mouse kidney fibrosis models.

Fabrication of Apparatus Specialized for Measuring the Elasticity of Perioral Tissues.

On the human face, the lips are one of the most important anatomical elements, both morphologically and functionally. Morphologically, they have a significant impact on aesthetics, and abnormal lip morphology causes sociopsychological problems. Functionally, they play a crucial role in breathing, articulation, feeding, and swallowing. An apparatus that can accurately and easily measure the elastic modulus of perioral tissues in clinical tests was developed, and its measurement sensitivity was evaluated. The apparatus is basically a uniaxial compression apparatus consisting of a force sensor and a displacement sensor. The displacement sensor works by enhancing the restoring force due to the deformation of soft materials. Using the apparatus, the force and the displacement were measured for polyurethane elastomers with various levels of softness, which are a model material of human tissues. The stress measured by the developed apparatus increased in proportion to Young's modulus, and was measured by the compression apparatus at the whole region of Young's modulus, indicating that the relation can be used for calibration. Clinical tests using the developed apparatus revealed that Young's moduli for upper lip, left cheek, and right cheek were evaluated to be 45, 4.0, and 9.9 kPa, respectively. In this paper, the advantages of this apparatus and the interpretation of the data obtained are discussed from the perspective of orthodontics.

Moisture Impact on Static and Dynamic Modulus of Elasticity in Structural Normal-Weight Concretes.

In the case of concrete built into a structure, the static secant modulus of elasticity (Ec,s) is often estimated based on its dynamic value (Ed) measured by the ultrasonic pulse velocity method instead of direct tests carried out on drilled cores. Meanwhile, the prevailing equations applied to estimate Ec,s often overlook the impact of concrete moisture. This study aimed to elucidate the moisture impact across two normal-weight structural concretes differing in compressive strength (51.6 and 71.4 MPa). The impact of moisture content was notably more evident only for the weaker concrete, according to dynamic modulus measurements. In other cases, contrary to the literature reports and expectations, this effect turned out to be insignificant. These observations may be explained by two factors: the relatively dense and homogeneous structure of tested concretes and reduced sensitivity of Ec,s measurements to concrete moisture condition compared to Ed measurements obtained using the ultrasonic method. Additionally, established formulas to estimate Ec,s were verified. The obtained modulus results tested under different moisture conditions of normal-weight concretes were also compared with those of lightweight aggregate concretes of identical volume compositions previously obtained in a separate study.

Research on Multiple-Factor Dynamic Constitutive Model of Poured Asphalt Concrete.

This study conducted dynamic triaxial tests on a typical poured asphalt concrete material of core walls in Xinjiang, exploring the dynamic characteristics of poured asphalt concrete under various confining pressures, principal stress ratios, and vibration frequencies. On this basis, the dynamic constitutive relationship of poured asphalt concrete was investigated using the Hardin-Drnevich model. The results indicate that under different confining pressures, principal stress ratios, and vibration frequencies, the variation patterns of the backbone lines of dynamic stress-strain of poured asphalt concrete are basically identical, consistent with a hyperbolic curve. The confining pressure and principal stress ratio significantly affect the backbone line of dynamic stress-strain. By comparison, frequency has a minimal effect. The changing trends of dynamic elasticity modulus and damping ratio of poured asphalt concrete under various factors are almost the same. When the material has high dynamic stress and strain, the hysteresis loop is large. When the curve of the damping ratio becomes flat, the asymptotic constant can be used as the maximum damping ratio. The relationship between the reciprocal of the dynamic elasticity modulus and the dynamic strain of poured asphalt concrete exhibits a linear distribution. Under different ratios of confining pressure to principal stress, there are large discrepancies between the calculated values from the formula and the experimental fitting values of the maximum dynamic elasticity modulus, and the maximum relative errors reach 16.65% and 18.15%, respectively. Therefore, the expression for the maximum dynamic elasticity modulus was modified, and the calculated values using the modified formula were compared with the experimental fitting values. The relative errors are significantly reduced, and the maximum relative errors are 3.02% and 2.04%, respectively, in good agreement with the fitting values of the experimental data. The findings of this article render a theoretical basis and reference for the promotion and application of poured asphalt concrete.

Hamstring Muscle Stiffness in Athletes with and without Anterior Cruciate Ligament Reconstruction History: A Retrospective Study.

Introduction: Sports requiring sprinting, jumping, and kicking tasks frequently lead to hamstring strain injuries (HSI). One of the structural risk factors of HSI is the increased passive stiffness of the hamstrings. Anterior cruciate ligament (ACL) injury history is associated with a 70% increase in the incidence of HSI, according to a recent meta-analysis. The same report recommended that future research should concentrate on the relationships between the HSI risk factors. Hence, the present study aimed to retrospectively compare changes in the passive stiffness of the hamstrings in athletes with and without ACL reconstruction history. Methods: Using ultrasound-based shear-wave elastography, the mid-belly passive muscle stiffness values of the biceps femoris long head, semimembranosus, and semitendinosus muscles were assessed and compared amongst athletes with and without a history of ACL reconstruction. Results: There were no significant differences in the biceps femoris long head (injured leg (IL): 26.19 ± 5.28 KPa, uninjured contralateral (UL): 26.16 ± 7.41 KPa, control legs (CL): 27.64 ± 5.58 KPa; IL vs. UL: p = 1; IL vs. CL: p = 1; UL vs. CL: p = 1), semimembranosus (IL: 24.35 ± 5.58 KPa, UL: 24.65 ± 8.35 KPa, CL: 22.83 ± 5.67 KPa; IL vs. UL: p = 1; IL vs. CL: p = 1; UL vs. CL, p = 1), or semitendinosus (IL: 22.45 ± 7 KPa, UL: 25.52 ± 7 KPa, CL: 22.54 ± 4.4 KPa; IL vs. UL: p = 0.487; IL vs. CL: p = 1; UL vs. CL, p = 0.291) muscle stiffness values between groups. Conclusions: The passive mid-muscle belly stiffness values of the biceps femoris long head, semitendinosus, and semimembranosus muscles did not significantly differ between previously injured and uninjured athletes; therefore, further assessment for other muscle regions of hamstrings may be necessary. To collect more comprehensive data related to the structural changes that may occur following ACL reconstructions in athletes, a future study should examine the passive stiffness of wider muscle regions from origin to insertion.

Overall constitutive properties of stratified lattices with alternating chirality.

The present research focuses on a continuum description of stratified metamaterials achieved through the superposition of layers with alternating chirality. Each layer is constructed as a periodic assembly of centre-symmetric periodic cells, formed by a recurring arrangement of rigid circular discs connected by elastic ligaments. The layers are interconnected through elastic pins passing through the centres of aligned discs, allowing for either restrained or free relative rotation. A micropolar continuum model is used to describe each individual layer. The overall response of the metamaterials to in-plane forces is derived using a multi-field non-local model, expressed in terms of the average and difference of displacement and rotational fields. The overall micropolar and standard (Cauchy) constitutive tensors have been determined in closed form. The validity of the equivalent generalized micropolar model has been confirmed through comparison with discrete Lagrangian solutions of representative examples. In addition, a detailed analysis of a pseudo-indentation test has been carried out. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 2)'.

Flexoelectric Enhancement of Strain Gradient Elasticity Across a Ferroelectric-to-Paraelectric Phase Transition.

We study the temperature dependent elastic properties of Ba0.8Sr0.2TiO3 freestanding membranes across the ferroelectric-to-paraelectric phase transition using an atomic force microscope. The bending rigidity of thin membranes can be stiffer compared to stretching due to strain gradient elasticity (SGE). We measure the Young's modulus of freestanding Ba0.8Sr0.2TiO3 drumheads in bending and stretching dominated deformation regimes on a variable temperature platform, finding a peak in the difference between the two Young's moduli obtained at the phase transition. This demonstrates a dependence of SGE on the dielectric properties of a material and alludes to a flexoelectric origin of an effective SGE.

Influence of collagen peptide supplementation on visible signs of skin and nail health and -aging in an East Asian population: A double blind, randomized, placebo-controlled trial.

BACKGROUND: A healthy skin provides protection against intrinsic and extrinsic factors. Skin aging is characterized by structural and morphological alterations affecting skin health, integrity, and functionality, resulting in visible aging signs. AIM: The primary objective of this study was to assess the effect of a collagen peptide dietary supplement on skin aging in the East Asian population. METHODS: Eighty-five healthy women, aged from 43 to 65 years old, were randomly assigned to the collagen supplement (CP, 5 g) or placebo (maltodextrin, 5 g) group. To standardize daily skin care, the volunteers in both groups used a specific face cream for 28 days prior to and throughout the supplementation period, creating an equal baseline for the assessment of the efficacy of CP on several skin parameters. At baseline, day 28 and day 84, the following hallmarks of skin and nail aging were assessed: dermis density, skin moisture and elasticity, wrinkle visibility, beauty perception, and nail color. RESULTS: After 84 days, a significant improvement of dermis density and skin moisture was observed in the collagen peptides group compared to the placebo group. Positive effects on skin elasticity, wrinkle visibility, nail color, and overall beauty perception were already observed within 28 days of supplementation in the CP group, while the same effects in the placebo group were only observed after 84 days. CONCLUSION: Taken together, these results show that, in addition to a standardized skin care, daily supplementation with 5 g of collagen peptides positively affects visible signs of skin and nail aging in the East Asian population.