The function of the brain is unlikely to be understood without an accurate description of its output, yet the nature of movement elements and their organization remains an open problem. Here, movement elements are identified from dynamics of walking in flies, using unbiased criteria. On one time scale, dynamics of walking are consistent over hundreds of milliseconds, allowing elementary features to be defined. Over longer periods, walking is well described by a stochastic process composed of these elementary features, and a generative model of this process reproduces individual behavior sequences accurately over seconds or longer. Within elementary features, velocities diverge, suggesting that dynamical stability of movement elements is a weak behavioral constraint. Rather, long-term instability can be limited by the finite memory between these elementary features. This structure suggests how complex dynamics may arise in biological systems from elements whose combination need not be tuned for dynamic stability.
Medical necessity (claiming that a medical intervention or care is – at minimum – reasonable, appropriate and acceptable) depends on empirical evidence and on the interpretation of that evidence. Evidence and its interpretation define the standard of care. This commentary argues that both the evidence base and its interpretation are currently weak gatekeepers. Empirical meta-research suggests that very few medical interventions have high quality evidence in support of their effectiveness and very few of them also have relatively thorough assessments of their potential harms. Therefore, evidence on the risk-benefit ratios carries almost always very large uncertainty. Arbitration about medical necessity is thus left to the interpretation process. Professional guidelines are notoriously unreliable and biased in this regard. Regulatory approval ends up being the key arbitrator, but over the years the regulatory process has been subverted. Regulatory approval currently does not mean that an intervention has a favourable risk-benefit ratio, but simply that it can be marketed, sold and made profit from. The process leads to a tragedy of commons where the final victim is society at large: medical necessity is invoked as an alibi for medicine to absorb societal resources.
Memories contain large arrays with high capacitance bitlines and IO lines. To reduce the power of memory accesses we limit the swings on these by controlling the time the lines are driven by using a replica feedback. The swings are set to 10% of the supply over a wide range of process and operating conditions.
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Purpose Many studies have reported on the use of narrow band imaging (NBI) colonoscopy to differentiate neoplastic from non-neoplastic colorectal polyps. It has potential to replace pathological diagnosis of diminutive polyps. We aimed to perform a systematic review and meta-analysis on the real-time diagnostic operating characteristics of NBI colonoscopy. Methods We searched PubMed, SCOPUS and Cochrane databases and abstracts. We used a two-level bivariate meta-analysis following a random effects model to summarise the data and fit hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve serves as an indicator of the diagnostic test strength. We calculated summary sensitivity, specificity and negative predictive value (NPV). We assessed agreement of surveillance interval recommendations based on endoscopic diagnosis compared to pathology. Results For NBI diagnosis of colorectal polyps, the area under the HSROC curve was 0.92 (95% CI 0.90 to 0.94), based on 28 studies involving 6280 polyps in 4053 patients. The overall sensitivity was 91.0% (95% CI 87.6% to 93.5%) and specificity was 82.6% (95% CI 79.0% to 85.7%). In eight studies (n=2146 polyps) that used high-confidence diagnostic predictions, sensitivity was 93.8% and specificity was 83.3%. The NPVs exceeded 90% when 60% or less of all polyps were neoplastic. Surveillance intervals based on endoscopic diagnosis agreed with those based on pathology in 92.6% of patients (95% CI 87.9% to 96.3%). Conclusions NBI diagnosis of colorectal polyps is highly accurate—the area under the HSROC curve exceeds 0.90. High-confidence predictions provide >90% sensitivity and NPV. It shows high potential for real-time endoscopic diagnosis.
Claims from highly cited observational studies persist and continue to be supported in the medical literature despite strong contradictory evidence from randomized trials.
Adaptive optics is used to compensate for modal dispersion in digital transmission through multimode fiber (MMF). At the transmitter, a spatial light modulator (SLM) controls the launched field pattern. An estimate of intersymbol interference (ISI) caused by modal dispersion is formed at the receiver and fed back to the transmitter, where the SLM is adjusted to minimize ISI. Error-free transmission of 10 Gbit∕s non-return-to-zero signals through standard 50 μm graded-index MMFs up to 11.1 km long is demonstrated. It is shown that a single SLM can compensate for modal dispersion across a 600 GHz bandwidth.
The IC industry is facing a huge paradox. On one hand, with the slowing of the performance and power gains provided by scaling, designers need to find new ways of delivering value to their customers. Historically this has meant creating more application specialized chips and systems. On the other hand the rising NRE costs for chip design (now over $10M/chip) has caused the number of chip design starts to fall. Everyone today seems to be talking about building programmable platforms to ensure the total available market is large enough to justify the chip design costs.
Abstract The scientific credibility of economics is itself a scientific question that can be addressed with both theoretical speculations and empirical data. In this review, we examine the major parameters that are expected to affect the credibility of empirical economics: sample size, magnitude of pursued effects, number and pre‐selection of tested relationships, flexibility and lack of standardization in designs, definitions, outcomes and analyses, financial and other interests and prejudices, and the multiplicity and fragmentation of efforts. We summarize and discuss the empirical evidence on the lack of a robust reproducibility culture in economics and business research, the prevalence of potential publication and other selective reporting biases, and other failures and biases in the market of scientific information. Overall, the credibility of the economics literature is likely to be modest or even low.
Summary form only given. The IC industry is facing a huge paradox. On one hand, with the slowing of the performance and power gains provided by scaling, designers need to find new ways of delivering value to their customers. Historically this has meant creating more application specialized chips and systems. On the other hand the rising NRE costs for chip design (now over $10M/chip) has caused the number of chip design starts to fall. Everyone today seems to be talking about building programmable platforms to ensure the total available market is large enough to justify the chip design costs. To get out of this paradox, we need to change the way we think about chip design. Reducing digital NRE costs requires moving the end user designers up a level in abstraction. For many reasons I don't believe that either the current SoC, or high-level language effort will succeed. Instead, we should acknowledge that working out the interactions in a complex design is complex, and will cost a lot of money, even when we do it well. The key is to leverage this work over a broader class of chips. This approach leads to the idea of building chip-generators and not chips. That is instead of building a programmable chip to meet a broad class of application needs, you create a virtual programmable chip, that is MUCH more flexible than any real chip. The application designer (the new chip designer) will then configure this substrate to optimize for their application. The generator will take this information and then create the desired chip. While there are many very hard problems that need to be addressed to make this work, but none of them seem insurmountable. In fact I will provide some examples which indicate the promise of this approach like having the generator choose the core that is the most energy efficient for your application mix.
[This corrects the article DOI: 10.1371/journal.pbio.1002501.].
A global clock network comprised of coupled, standing-wave oscillators is prototyped in a 0.18/spl mu/m 6M CMOS process. The clock network operates from 9.8 to 10.5 GHz with 0.6ps skew and contributes only 0.5ps jitter when referencing a clock source with 1.4ps rms jitter.
