Analytical and experimental analysis of guided waves in an aluminum plate under bending load.

Although guided waves offer great potential for monitoring various structures, interpreting signals from piezoelectric sensors remains a challenging task. One main reason is the significant influence of environmental conditions on the wave propagation. A lot of research has already been done on the influence of temperature effects and recently more attention has been shifted towards loads. While previous publications have mainly focused on uni- or bi-directional loads, this publication expands the developed models to include bending loads. After reviewing the analytical basis of acoustoelasticity, the derived equations are expanded to nonhomogeneous elastic bending loads using the partial wave method. The analysis is completed using recent results developed by C. Hakoda and C. J. Lissenden (2018) [1], that gave more physical insight in the propagation of guided waves in various frequency-bands. The focus of the experimental analysis is around the fundamental S0- and A0-Modes of Lamb waves. To validate the analytical results an aluminum plate is instrumented using piezoelectric transducers and loaded with varying bending loads. The experimental results are in good agreement with the analytical theory and demonstrate the influence of bending prestress on guided wave propagation. Based on these results an innovative measurement method for bending loads is developed, that is robust to small temperature changes.

Episodic Memory Retrieval Affects the Onset and Dynamics of Evidence Accumulation during Value-based Decisions.

In neuroeconomics, there is much interest in understanding simple value-based choices where agents choose between visually presented goods, comparable to a shopping scenario in a supermarket. However, many everyday decisions are made in the physical absence of the considered goods, requiring agents to recall information about the goods from memory. Here, we asked whether and how this reliance on an internal memory representation affects the temporal dynamics of decision making on a cognitive and neural level. Participants performed a remember-and-decide task in which they made simple purchasing decisions between money offers and snack items while undergoing EEG. Snack identity was presented either visually (value trials) or had to be recalled from memory (memory trials). Behavioral data indicated comparable choice consistency across both trial types, but considerably longer RTs in memory trials. Drift-diffusion modeling suggested that this RT difference was because of longer nondecision time of decision processes as well as altered evidence accumulation dynamics (lower accumulation rate and higher decision threshold). The nondecision time effect was supported by a delayed onset of the lateralized readiness potential. These results show that both decision and nondecision processes are prolonged when participants need to resort to internal memory representations during value-based decisions.

Cognitive and neural principles of a memory bias on preferential choices.

Value-based decisions depend on different forms of memory. However, the respective roles of memory and valuation processes that give rise to these decisions are often vaguely described and have rarely been investigated jointly. In this review article, we address the problem of memory-based decision making from a neuroeconomic perspective. We first describe the neural and cognitive processes involved in decisions requiring memory processes, with a focus on episodic memory. Based on the results of a systematic research program, we then spotlight the phenomenon of the memory bias, a general preference for choice options that can be retrieved from episodic memory more successfully. Our findings indicate that failed memory recall biases neural valuation processes as indicated by altered effective connectivity between the hippocampus and ventromedial prefrontal cortex. This bias can be attributed to meta-cognitive beliefs about the relationship between subjective value and memory as well as to uncertainty aversion. After summarizing the findings, we outline potential future research endeavors to integrate the two research traditions of memory and decision making.

Response time models separate single- and dual-process accounts of memory-based decisions.

Human decisions often deviate from economic rationality and are influenced by cognitive biases. One such bias is the memory bias according to which people prefer choice options they have a better memory of-even when the options' utilities are comparatively low. Although this phenomenon is well supported empirically, its cognitive foundation remains elusive. Here we test two conceivable computational accounts of the memory bias against each other. On the one hand, a single-process account explains the memory bias by assuming a single biased evidence-accumulation process in favor of remembered options. On the contrary, a dual-process account posits that some decisions are driven by a purely memory-driven process and others by a utility-maximizing one. We show that both accounts are indistinguishable based on choices alone as they make similar predictions with respect to the memory bias. However, they make qualitatively different predictions about response times. We tested the qualitative and quantitative predictions of both accounts on behavioral data from a memory-based decision-making task. Our results show that a single-process account provides a better account of the data, both qualitatively and quantitatively. In addition to deepening our understanding of memory-based decision-making, our study provides an example of how to rigorously compare single- versus dual-process models using empirical data and hierarchical Bayesian parameter estimation methods.

The Reflection Effect in Memory-Based Decisions.

Previous research has indicated a bias in memory-based decision-making, with people preferring options that they remember better. However, the cognitive mechanisms underlying this memory bias remain elusive. Here, we propose that choosing poorly remembered options is conceptually similar to choosing options with uncertain outcomes. We predicted that the memory bias would be reduced when options had negative subjective value, analogous to the reflection effect, according to which uncertainty aversion is stronger in gains than in losses. In two preregistered experiments (N = 36 each), participants made memory-based decisions between appetitive and aversive stimuli. People preferred better-remembered options in the gain domain, but this behavioral pattern reversed in the loss domain. This effect was not related to participants' ambiguity or risk attitudes, as measured in a separate task. Our results increase the understanding of memory-based decision-making and connect this emerging field to well-established research on decisions under uncertainty.

Therapy of heavy menstrual bleeding in Korea: Subanalysis and results from a multinational clinical trial in the Asian region investigating the levonorgestrel-releasing intrauterine system versus conventional therapy.

OBJECTIVE: To compare real-life clinical outcomes with the levonorgestrel-releasing intrauterine system (LNG-IUS) and conventional medical therapies (CMTs), including combined oral contraceptives and oral progestins in the treatment of idiopathic heavy menstrual bleeding (HMB) in South Korea. METHODS: This prospective, observational cohort study recruited a total of 647 women aged 18 to 45 years, diagnosed with HMB from 8 countries in Asia, including 209 women from South Korea (LNG-IUS, 169; CMTs, 40), who were followed up to one year. The primary outcome was cumulative continuation rate (still treated with LNG-IUS and CMTs) at 12 months. Secondary outcomes included bleeding pattern, assessment of the treatment efficacy by treating physician and safety profile. RESULTS: The continuation rate at 12 months was significantly higher with the LNG-IUS than CMTs (85.1% vs. 48.5%, respectively; P<0.0001). The 51.5% of CMTs patients discontinued treatment and 18.8% of LNG-IUS patients discontinued treatment. The most common reasons for discontinuation for CMTs were switching to another treatment and personal reasons. When compared to CMTs, the LNG-IUS offered better reduction in subjectively assessed menstrual blood loss and the number of bleeding days, tolerability and with better efficacy in HMB, as assessed by physician's final evaluation. CONCLUSION: This study provides novel information on the real-life treatment patterns of HMB in South Korea. The efficacy of CMTs was inferior compared to the LNG-IUS in the clinical outcomes measured in this study. Due to the better compliance with LNG-IUS, the cumulative continuation rate is higher than CMTs. We conclude that the LNG-IUS should be used as the first-line treatment for HMB in Korean women, in line with international guidelines.

Satisfaction and health-related quality of life in women with heavy menstrual bleeding; results from a non-interventional trial of the levonorgestrel-releasing intrauterine system or conventional medical therapy.

PURPOSE: To evaluate the patient satisfaction and health related quality of life (HRQoL) for levonorgestrel-releasing intrauterine system (LNG-IUS) versus conventional medical treatments ([CMTs] combined oral contraceptives, oral progestins, and antifibrinolytics, alone or in combination) in Asian women with heavy menstrual bleeding (HMB). PATIENTS AND METHODS: A total of 647 patients diagnosed with HMB were recruited to this non-interventional study from the eight participating countries in Asia. Patient satisfaction was recorded at the last visit (at 12 months or premature discontinuation). At each visit (at 3, 6, and 12 months), patients completed the menorrhagia multi-attribute scale (MMAS) to assess HRQoL. RESULTS: A total of 83.5% of patients on the LNG-IUS were "very satisfied" or at least "satisfied" with the therapeutic effect of HMB treatment, compared with 59.2% of patients with CMTs (P<0.05). The mean (± standard deviation) MMAS score increased from 41.4±24.5 to 87.7±21.4 in the LNG-IUS arm, and from 44.1±24.9 to 73.1±25.3 in the CMTs arm. This increase was significantly higher in patients on the LNG-IUS, as compared with those on CMTs (P<0.05). The improvement in HRQoL in both treatment groups correlated with the body mass index of the patient, with larger improvement obtained in women with a higher body mass index. CONCLUSION: The majority of women using the LNG-IUS or CMTs for HMB were satisfied with their treatment, and both treatment modalities were associated with significant improvements in HRQoL over time. The improvement was greater with the LNG-IUS, compared with CMTs.

EUnetHTA information management system: development and lessons learned.

OBJECTIVES: The aim of this study was to describe the techniques used in achieving consensus on common standards to be implemented in the EUnetHTA Information Management System (IMS); and to describe how interoperability between tools was explored. METHODS: Three face to face meetings were organized to identify and agree on common standards to the development of online tools. Two tools were created to demonstrate the added value of implementing interoperability standards at local levels. Developers of tools outside EUnetHTA were identified and contacted. RESULTS: Four common standards have been agreed on by consensus; and consequently all EUnetHTA tools have been modified or designed accordingly. RDF Site Summary (RSS) has demonstrated a good potential to support rapid dissemination of HTA information. Contacts outside EUnetHTA resulted in direct collaboration (HTA glossary, HTAi Vortal), evaluation of options for interoperability between tools (CRD HTA database) or a formal framework to prepare cooperation on concrete projects (INAHTA projects database). CONCLUSIONS: While being entitled a project on IT infrastructure, the work program was also about people. When having to agree on complex topics, fostering a cohesive group dynamic and hosting face to face meetings brings added value and enhances understanding between partners. The adoption of widespread standards enhanced the homogeneity of the EUnetHTA tools and should thus contribute to their wider use, therefore, to the general objective of EUnetHTA. The initiatives on interoperability of systems need to be developed further to support a general interoperable information system that could benefit the whole HTA community.

Levonorgestrel-releasing intrauterine system versus conventional medical therapy for heavy menstrual bleeding in the Asia-Pacific region.

OBJECTIVE: To compare clinical outcomes, including cumulative continuation rate (CCR), in the treatment of idiopathic heavy menstrual bleeding (HMB) with the levonorgestrel-releasing intrauterine system (LNG-IUS) and with conventional medical therapies (CMTs), including combined oral contraceptives, oral progestins, and antifibrinolytics, either alone or in combination, in the Asia-Pacific region. METHODS: In a prospective observational cohort study conducted between September 2008 and December 2010, 647 women (LNG-IUS, n=483; CMTs, n=164), aged 18-45 years and diagnosed with HMB, were recruited from 8 countries and followed for up to 1 year. The primary outcome was the CCR at 12 months. Secondary outcomes included bleeding pattern, an assessment of treatment efficacy by the treating physician, and safety. RESULTS: The CCR at 12 months was significantly higher for LNG-IUS than for CMTs (87.6% vs 56.3% P<0.05). Compared with CMTs, LNG-IUS offered a better reduction in both subjectively assessed menstrual blood loss and the number of bleeding days, and had better efficacy for HMB, as determined by the physician's final evaluation. CONCLUSION: The present study provides information on the real-life patterns of treatment of HMB in the Asia-Pacific region. The efficacy of CMTs was inferior compared with LNG-IUS in the clinical outcomes measured. ClinicalTrials.gov:NCT00864136.

TheClinical Research Tool: a high-performance microdialysis-based system for reliably measuring interstitial fluid glucose concentration.

BACKGROUND: A novel microdialysis-based continuous glucose monitoring system, the so-called Clinical Research Tool (CRT), is presented. The CRT was designed exclusively for investigational use to offer high analytical accuracy and reliability. The CRT was built to avoid signal artifacts due to catheter clogging, flow obstruction by air bubbles, and flow variation caused by inconstant pumping. For differentiation between physiological events and system artifacts, the sensor current, counter electrode and polarization voltage, battery voltage, sensor temperature, and flow rate are recorded at a rate of 1 Hz. METHOD: In vitro characterization with buffered glucose solutions (c(glucose) = 0 - 26 x 10(-3) mol liter(-1)) over 120 h yielded a mean absolute relative error (MARE) of 2.9 +/- 0.9% and a recorded mean flow rate of 330 +/- 48 nl/min with periodic flow rate variation amounting to 24 +/- 7%. The first 120 h in vivo testing was conducted with five type 1 diabetes subjects wearing two systems each. A mean flow rate of 350 +/- 59 nl/min and a periodic variation of 22 +/- 6% were recorded. RESULTS: Utilizing 3 blood glucose measurements per day and a physical lag time of 1980 s, retrospective calibration of the 10 in vivo experiments yielded a MARE value of 12.4 +/- 5.7. Clarke error grid analysis resulted in 81.0%, 16.6%, 0.8%, 1.6%, and 0% in regions A, B, C, D, and E, respectively. CONCLUSION: The CRT demonstrates exceptional reliability of system operation and very good measurement performance. The ability to differentiate between artifacts and physiological effects suggests the use of the CRT as a reference tool in clinical investigations.

Role of insulin in the progression of ovarian sex cord stromal tumors in rats.

PURPOSE: This study examined the effect of insulin on sex cord stromal tumors in the rat. METHODS: Sex cord stromal tumors were induced by transplantation of ovaries under the splenic capsule of ovariectomized rats (Lewis-inbred). These tumors were then transplanted into new inbred rats. Hyperglycemic conditions were induced by treatment with streptozotocin (STZ, which selectively destroyed pancreatic islet cells) and hypoglycemic conditions by treatment with a subcutaneously implanted insulin pump (Alzet). The animals were killed 28, 56, and 84 days later. Tumor growth, animal weight, food and water consumption, and serum concentrations of glucose, FSH, LH, and estradiol were measured. RESULTS: Treatment with STZ and insulin with osmotic Alzet pumps induced continuous hypoglycemic and hyperglycemic conditions, respectively. No significant influence of the hypoglycemic or hyperglycemic status on tumor growth was measured during the first 28 and 56 days. Eighty-four days after transplantation and substitution of 1 or 2 IU/100 g body weight/d insulin, there was a significant stimulation of tumor growth (2.2-fold and 2.7-fold, respectively). In hyperglycemic animals (treated with STZ), no influence on tumor growth was found in comparison with the controls. CONCLUSION: This study confirms that hyperinsulinemic conditions contribute to the progression of tumors.