Regenerative Thermoelectric Cooling for Implantable Medical Devices

Implantable Medical Devices (IMDs) are a category of medical devices that include pacemakers, implantable cardiac defibrillators, spinal cord stimulators, and many other devices. Many of these devices are battery-powered such as pacemakers which last an average of 7 years before needing to be replaced via surgery. This research focuses on re-chargeable IMD’s such as spinal cord stimulators. Re-chargeable IMD’s often require daily charging to operate which can be a burden on the patient. Shorter charge times are desired for improved usability. One significant limitation of these re-chargeable IMD’s is that the charging current is reduced from optimal levels to mitigate heat buildup of the device. A high heat generation during charging is not acceptable due to FDA regulations that IMD’s are bound by. This heat is primarily emitted from the charging battery-element within the IMD and can be harmful to human patients. Unfortunately, limiting the current throughput as a solution for the generated heat, results in a longer charging time that affects a patient’s quality of life. This paper serves to document the research performed on the integration of thermoelectric generators (TEGs) in such medical devices. It will present the thermal impacts that a TEG has when operating under similar conditions as an IMD. The TEG serves to harvest the heat energy that is normally wasted by the battery and convert it into electrical energy. The conversion from heat into electrical energy serves as a cooling mechanism for the system that correlates with the resulting charging times of IMD’s. A maximized cooling effect implemented by the TEG will further reduced IMD charging times. The mitigation of heat being introduced to the system will allow for increased charge current to be safely introduced, further increasing the rate of charge. This research will explore how effective thermoelectric devices can be in reducing the charge time for these medical devices. Ultimately, this research aims to increase the quality of life for IMD patients by addressing the thermal obstacle present in these devices

The Effects of Auditor Tenure on Fraud and Its Detection

We examine the strategic effects of auditor tenure on the auditor's testing strategy and the manager's inclination to commit fraud. Most empirical studies conclude that longer tenure improves audit quality. Proponents of restricting tenure argue that longer tenure impairs auditor independence and a "fresh look" from a new auditor results in higher audit quality. Validating this argument requires testing whether the observed difference in audit quality between a continuing auditor and a change in auditors is less than the theoretically expected difference in audit quality without impairment. Our findings provide the guidance necessary for developing such tests. Our results show that audit risk (the probability that fraud exists and goes undetected) is lower in both periods for the continuing auditor than with a change in auditors. More importantly, we show that across both periods, expected undetected fraud is lower for the continuing auditor than with a change in auditors

Effect of Progressive Weight Loss on Lactate Metabolism: A Randomized Controlled Trial.

OBJECTIVE:Lactate is an intermediate of glucose metabolism that has been implicated in the pathogenesis of insulin resistance. This study evaluated the relationship between glucose kinetics and plasma lactate concentration ([LAC]) before and after manipulating insulin sensitivity by progressive weight loss. METHODS:Forty people with obesity (BMI = 37.9 ± 4.3 kg/m2 ) were randomized to weight maintenance (n = 14) or weight loss (n = 19). Subjects were studied before and after 6 months of weight maintenance and before and after 5%, 11%, and 16% weight loss. A hyperinsulinemic-euglycemic clamp procedure in conjunction with [6,6-2 H2 ]glucose tracer infusion was used to assess glucose kinetics. RESULTS:At baseline, fasting [LAC] correlated positively with endogenous glucose production rate (r = 0.532; P = 0.001) and negatively with insulin sensitivity, assessed as the insulin-stimulated glucose disposal (r = -0.361; P = 0.04). Progressive (5% through 16%) weight loss caused a progressive decrease in fasting [LAC], and the decrease in fasting [LAC] after 5% weight loss was correlated with the decrease in endogenous glucose production (r = 0.654; P = 0.002) and the increase in insulin sensitivity (r = -0.595; P = 0.007). CONCLUSIONS:This study demonstrates the interrelationships among weight loss, hepatic and muscle glucose kinetics, insulin sensitivity, and [LAC], and it suggests that [LAC] can serve as an additional biomarker of glucose-related insulin resistance

The Interrelation between Audit Quality and Managerial Reporting Choices and Its Effects on Financial Reporting Quality

Two distinct lines of research have been dedicated to empirically testing how financial reporting quality (measured as the earnings response coefficient or ERC) is associated with management's choice of reporting bias and with audit quality. However, researchers have yet to consider how ERCs are affected by either the auditor's reaction to changes in the manager's reporting bias or the manager's reaction to changes in audit quality. Our study provides theoretical guidance on these interrelations and how changes in the manager's or the auditor's incentives affect both reporting bias and audit quality. Specifically, when the manager's cost (benefit) of reporting bias increases (decreases), we find that expected bias decreases, inducing the auditor to react by reducing audit quality. Because we also find that the association between expected audit quality and ERCs is always positive, changes in managerial incentives for biased reporting lead to a positive association between ERCs and expected reporting bias. When the cost of auditing decreases or the cost of auditor liability increases, we find that expected audit quality increases, inducing the manager to react by decreasing reporting bias. In this case, changes in the costs of audit quality lead to a negative association between ERCs and expected reporting bias. Finally, we demonstrate the impact of our theoretical findings by focusing on the empirical observations documented in the extant literature on managerial ownership and accounting expertise on the audit committee. In light of our framework, we provide new interpretations of these empirical observations and new predictions for future research

β Cell function after Roux-en-Y gastric bypass surgery or reduced energy intake alone in people with obesity

BackgroundThe effects of diet-induced weight loss (WL) and WL after Roux-en-Y gastric bypass (RYGB) surgery on β cell function (BCF) are unclear because of conflicting results from different studies, presumably because of differences in the methods used to measure BCF, the amount of WL between treatment groups, and baseline BCF. We evaluated the effect of WL after RYGB surgery or reduced energy intake alone on BCF in people with obesity with and without type 2 diabetes.MethodsBCF (insulin secretion in relationship to plasma glucose) was assessed before and after glucose or mixed-meal ingestion before and after (a) progressive amounts (6%, 11%, 16%) of WL induced by a low-calorie diet (LCD) in people with obesity without diabetes, (b) ~20% WL after RYGB surgery or laparoscopic adjustable gastric banding (LAGB) in people with obesity without diabetes, and (c) ~20% WL after RYGB surgery or LCD alone in people with obesity and diabetes.ResultsDiet-induced progressive WL in people without diabetes progressively decreased BCF. Marked WL after LAGB or RYGB in people without diabetes did not alter BCF. Marked WL after LCD or RYGB in people with diabetes markedly increased BCF, without a difference between groups.ConclusionMarked WL increases BCF in people with obesity and diabetes but not in people with obesity without diabetes. The effect of RYGB-induced WL on BCF is not different from the effect of matched WL after LAGB or LCD alone.trial registrationNCT00981500, NCT02207777, NCT01299519.FundingNIH grants R01 DK037948, P30 DK056341, P30 DK020579, UL1 TR002345

How Changes in Expectations of Earnings Affect the Associations of Earnings Overstatements and Audit Effort with Audit Risk and Market Price

In this study, we provide theoretical guidance for both analytical research and empirical research by considering how changing expectations of earnings affect a dishonest manager's strategy to overstate earnings and an auditor's strategy to exert effort in a two-period setting. We expect our study's insights on changing economic conditions to help shape future research. We model the manager type as either honest or dishonest, which allows us to differentiate audit risk from audit effort. The key takeaways for future research are the insights on how changes in payoffs and expected earnings affect the associations that involve earnings overstatements and audit effort with audit risk and market price. For instance, researchers typically assume audit effort and audit risk are negatively associated, but we find the association can be positive when, for example, the auditor chooses a period 2 strategy based on the changes in period 1 game parameters. The results of our study provide two additional key insights on the design of future empirical tests. First, by dichotomizing, we show the importance of estimating the intercept in the market pricing equation when studying earnings quality, because market price also adjusts for expected bias through changes in the intercept. Second, our multiperiod setting demonstrates that the effects from a change in the manager's or auditor's incentives in period 1 may reverse in period 2. Empirical studies typically examine the contemporaneous effects of these changes on market price and/or audit risk but fail to identify the cross-temporal effects we document in our study

Foxc1 is required by pericytes during fetal brain angiogenesis

Summary Brain pericytes play a critical role in blood vessel stability and blood–brain barrier maturation. Despite this, how brain pericytes function in these different capacities is only beginning to be understood. Here we show that the forkhead transcription factor Foxc1 is expressed by brain pericytes during development and is critical for pericyte regulation of vascular development in the fetal brain. Conditional deletion of Foxc1 from pericytes and vascular smooth muscle cells leads to late-gestation cerebral micro-hemorrhages as well as pericyte and endothelial cell hyperplasia due to increased proliferation of both cell types. Conditional Foxc1 mutants do not have widespread defects in BBB maturation, though focal breakdown of BBB integrity is observed in large, dysplastic vessels. qPCR profiling of brain microvessels isolated from conditional mutants showed alterations in pericyte-expressed proteoglycans while other genes previously implicated in pericyte–endothelial cell interactions were unchanged. Collectively these data point towards an important role for Foxc1 in certain brain pericyte functions (e.g. vessel morphogenesis) but not others (e.g. barriergenesis)