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7,834 result(s) for "Johnson, Matthew A."
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Successful Creation of Tissue-Engineered Autologous Auricular Cartilage in an Immunocompetent Large Animal Model
Tissue-engineered cartilage has historically been an attractive alternative treatment option for auricular reconstruction. However, the ability to reliably generate autologous auricular neocartilage in an immunocompetent preclinical model should first be established. The objectives of this study were to demonstrate engineered autologous auricular cartilage in the immunologically aggressive subcutaneous environment of an immunocompetent animal model, and to determine the impact of in vitro culture duration of chondrocyte-seeded constructs on the quality of neocartilage maturation in vivo . Auricular cartilage was harvested from eight adult sheep; chondrocytes were isolated, expanded in vitro , and seeded onto fibrous collagen scaffolds. Constructs were cultured in vitro for 2, 6, and 12 weeks, and then implanted autologously in sheep and in control nude mice for 6 and 12 weeks. Explanted tissue was stained with hematoxylin and eosin, safranin O, toluidine blue, collagen type II, and elastin. DNA and glycosaminoglycans (GAGs) were quantified. The quality of cartilage engineered in sheep decreased with prolonged in vitro culture time. Superior cartilage formation was demonstrated after 2 weeks of in vitro culture; the neocartilage quality improved with increased implantation time. In nude mice, neocartilage resembled native sheep auricular cartilage regardless of the in vitro culture length, with the exception of elastin expression. The DNA quantification was similar in all engineered and native cartilage ( p >0.1). All cartilage engineered in sheep had significantly less GAG than native cartilage ( p <0.02); significantly more GAG was observed with increased implantation time ( p <0.02). In mice, the GAG content was similar to that of native cartilage and became significantly higher with increased in vitro or in vivo durations ( p <0.02). Autologous auricular cartilage was successfully engineered in the subcutaneous environment of an ovine model using expanded chondrocytes seeded on a fibrous collagen scaffold after a 2-week in vitro culture period.
Risk-taking bias in human decision-making is encoded via a right–left brain push–pull system
A person’s decisions vary even when options stay the same, like when a gambler changes bets despite constant odds of winning. Internal bias (e.g., emotion) contributes to this variability and is shaped by past outcomes, yet its neurobiology during decision-making is not well understood. To map neural circuits encoding bias, we administered a gambling task to 10 participants implanted with intracerebral depth electrodes in cortical and subcortical structures. We predicted the variability in betting behavior within and across patients by individual bias, which is estimated through a dynamical model of choice. Our analysis further revealed that high-frequency activity increased in the right hemisphere when participants were biased toward risky bets, while it increased in the left hemisphere when participants were biased away from risky bets. Our findings provide electrophysiological evidence that risk-taking bias is a lateralized push–pull neural system governing counterintuitive and highly variable decision-making in humans.
Lucky Rhythms in Orbitofrontal Cortex Bias Gambling Decisions in Humans
It is well established that emotions influence our decisions, yet the neural basis of this biasing effect is not well understood. Here we directly recorded local field potentials from the OrbitoFrontal Cortex (OFC) in five human subjects performing a financial decision-making task. We observed a striking increase in gamma-band (36–50 Hz) oscillatory activity that reflected subjects’ decisions to make riskier choices. Additionally, these gamma rhythms were linked back to mismatched expectations or “luck” occurring in past trials. Specifically, when a subject expected to win but lost, the trial was defined as “unlucky” and when the subject expected to lose but won, the trial was defined as “lucky”. Finally, a fading memory model of luck correlated to an objective measure of emotion, heart rate variability. Our findings suggest OFC may play a pivotal role in processing a subject’s internal (emotional) state during financial decision-making, a particularly interesting result in light of the more recent “cognitive map” theory of OFC function.
The influences and neural correlates of past and present during gambling in humans
During financial decision-making tasks, humans often make “rational” decisions, where they maximize expected reward. However, this rationality may compete with a bias that reflects past outcomes. That is, if one just lost money or won money, this may impact future decisions. It is unclear how past outcomes influence future decisions in humans, and how neural circuits encode present and past information. In this study, six human subjects performed a financial decision-making task while we recorded local field potentials from multiple brain structures. We constructed a model for each subject characterizing bets on each trial as a function of present and past information. The models suggest that some patients are more influenced by previous trial outcomes ( i . e ., previous return and risk) than others who stick to more fixed decision strategies. In addition, past return and present risk modulated with the activity in the cuneus; while present return and past risk modulated with the activity in the superior temporal gyrus and the angular gyrus, respectively. Our findings suggest that these structures play a role in decision-making beyond their classical functions by incorporating predictions and risks in humans’ decision strategy, and provide new insight into how humans link their internal biases to decisions.
Erratum: Lucky Rhythms in Orbitofrontal Cortex Bias Gambling Decisions in Humans
Scientific Reports 6: Article number: 36206; published online: 10 November 2016; updated: 16 February 2017 Affiliation 1 was incorrectly listed as ‘Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21211, USA’ in the original version of the Article. The correct affiliation is listed below:
A Study of Scala Repositories on Github
Functional programming appears to be enjoying a renaissance of interest for developing practical, “real-world” applications. Proponents have long maintained that the functional style is a better way to modularize programs and reduce complexity. What is new in this paper is we test this claim by studying the complexity of open source codes written in Scala, a modern language that unifies functional and object programming. We downloaded from GitHub, Inc., a portfolio of mostly “trending” Scala repositories that included the Scala compiler and standard library, much of them written in Scala; the Twitter, Inc., server and its support libraries; and many other repositories, several of them production-oriented and commercially inspired. In total we investigated approximately 22,000 source files with 2 millions lines of code and 223,000 methods written by hundreds of programmers. To analyze these sources, we developed a novel compiler kit that measures lines of code and adaptively learns to estimate the cyclomatic complexity of functional-object codes. The data show, first, lines of code and cyclomatic complexity are positively correlated as we expected but only weakly which we did not expect with Kendall’s t=0.258–0.274. Second, 75% of the Scala methods are straight-line, that is, they have the lowest possible cyclomatic complexity. Third, nearly 70% of methods have three or fewer lines. Fourth, the distributions of lines of code and cyclomatic complexity are both non-Gaussian (P<0.01), which is as surprising as it is interesting. These data may offer new insights into software complexity and the large-scale structure of applications including but not necessarily limited to Scala.
A one sided story
The clinical meetings are time consuming and in our experience of limited benefit. A survey of patients engaged in the project that was published a few months ago was highly uncomplimentary, something the author neglects to mention.
Central obesity: Association with left ventricular dysfunction and mortality in the community
We sought to measure the strength of association between 2 indices of obesity, waist-hip ratio (WHR) and body mass index (BMI), with left ventricular (LV) dysfunction and mortality in a community cohort. The distribution of body fat is thought to affect cardiovascular disease risk. The association of BMI (an index of overall obesity) and WHR (an index of central obesity) with LV systolic and diastolic dysfunction in a population-based cohort is unknown. Anthropomorphic measurements and echocardiographic LV function were measured in a cross-sectional population-based sample of 2,042 men and women >45 years old in the Olmsted County Heart Function Study. Five-year prospective mortality was measured. Increased WHR had a stronger association than BMI with (1) lower LV ejection fraction ( r = −0.24, P < .0001 vs r = −0.04, P = .09) and (2) LV diastolic dysfunction ( r = 0.18, P < .0001 vs r = 0.05, P = .02). After adjustment for standard cardiovascular risk factors, WHR continued to be significantly associated with diastolic dysfunction but not with systolic dysfunction. Waist-hip ratio, but not BMI, was strongly predictive of all-cause mortality independent of age and sex (hazard ratio 23.6, CI 4.0-139.8, P = .0005). This relationship was attenuated on adjustment for diastolic dysfunction. Waist-hip ratio is a stronger correlate of LV dysfunction and mortality than BMI. These cross-sectional data suggest that the increased risk of mortality from central obesity is mediated at least in part by LV dysfunction, especially diastolic dysfunction.
Parma: Confidential Containers via Attested Execution Policies
Container-based technologies empower cloud tenants to develop highly portable software and deploy services in the cloud at a rapid pace. Cloud privacy, meanwhile, is important as a large number of container deployments operate on privacy-sensitive data, but challenging due to the increasing frequency and sophistication of attacks. State-of-the-art confidential container-based designs leverage process-based trusted execution environments (TEEs), but face security and compatibility issues that limits their practical deployment. We propose Parma, an architecture that provides lift-and-shift deployment of unmodified containers while providing strong security protection against a powerful attacker who controls the untrusted host and hypervisor. Parma leverages VM-level isolation to execute a container group within a unique VM-based TEE. Besides container integrity and user data confidentiality and integrity, Parma also offers container attestation and execution integrity based on an attested execution policy. Parma execution policies provide an inductive proof over all future states of the container group. This proof, which is established during initialization, forms a root of trust that can be used for secure operations within the container group without requiring any modifications of the containerized workflow itself (aside from the inclusion of the execution policy.) We evaluate Parma on AMD SEV-SNP processors by running a diverse set of workloads demonstrating that workflows exhibit 0-26% additional overhead in performance over running outside the enclave, with a mean 13% overhead on SPEC2017, while requiring no modifications to their program code. Adding execution policies introduces less than 1% additional overhead. Furthermore, we have deployed Parma as the underlying technology driving Confidential Containers on Azure Container Instances.