Gaining confidence on the correct realization of arbitrary quantum computations

We present verification protocols to gain confidence in the correct performance of the realization of an arbitrary universal quantum computation. The derivation of the protocols is based on the fact that matchgate computations, which are classically efficiently simulable, become universal if supplemented with additional resources. We combine tools from weak simulation, randomized compiling, and classical statistics to derive verification circuits. These circuits have the property that (i) they strongly resemble the original circuit and (ii) cannot only be classically efficiently simulated in the ideal, i.e. error free, scenario, but also in the realistic situation where errors are present. In fact, in one of the protocols we apply exactly the same circuit as in the original computation, however, to a slightly modified input state.Comment: 17 pages, 8 figure

Effectiveness of an R-based software to detect closed-loop cardiovascular interactions and baroreflex impairment in human subjects from the EUROBAVAR data set

We recently developed an R-based software that could model closedloop cardiovascular interactions. In this study, we applied this tool on the EUROBAVAR data set to further test its applicability. The aim of this work is to test the effectiveness of our software to identify cardiovascular regulatory mechanisms and baroreflex impairment from these data. We first uploaded each recording into our software to model the interactions present between systolic blood pressure (SBP) and IBI by employing a wavelet detrending and multivariate autoregressive modeling algorithm. Then, our software estimated causal coherence and Gaussian-weighted baroreflex sensitivity (BRS) indexes from each model at the low frequency (LF, 0.04-0.15 Hz, sympathetic) and high frequency (HF, 0.15-0.4 Hz, parasympathetic) bands. Immediate variability transfer from SBP to IBI was also computed for each subject. Our results showed that, when standing, the estimates of only two subjects, B005 and B010, were below percentile P10 of the BRS distribution (0.719 ms/mmHg at HF, 1.678 ms/mmHg at LF) at both bands. A literature review indicated that these two subjects had a baroreflex impairment. In non-baroreflex-impaired subjects, causal coherence from IBI to SBP at LF was significantly predominant at rest when compared with the coupling from SBP to IBI (p < 0.001). This predominance disappeared during standing due to changes in the couplings, suggesting a baroreflex interaction. Closed-loop BRS supineto- standing ratios in these subjects were 1.69 ± 0.93 (LF band) and 3.1 ± 1.32 (HF band), showing a significantly decreased BRS during standing position (p < 0.01, LF; p < 0.001, HF). Immediate transfer also decreased during standing (p < 0.001). In conclusion, our software managed to evaluate causal closed-loop interactions between cardiovascular variables from the data set, evidencing a baroreflex coupling, Thus, this allows it to be a useful tool for baroreceptor evaluations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Peer-to-peer medical student education: design, experience and evaluation of the impact in learning of 2nd year medical students from the University of Malaga

Escape rooms have been trending in the past years among young adults, as teamwork, ingenuity and knowledge merge in a both distended but competitive environment. Inspired by it, a physiology escape room was designed for second year medical students of the Faculty of Medicine in Malaga on a peer-to-peer teaching basis. Indeed, physiology intern students from higher courses structured a practical escape room that covered the topics of the first human physiology course, focusing on cardiovascular and respiratory physiology. As a result, these students replaced regular teachers in this activity, taking control of the design, promotion, preparation, execution, evaluation and follow-up of the event. The escape room was done in mid-December, when all practical and theoretical content of the subject had already been delivered. It was divided in four stages, two for each topic, adding a final case, connected to the beginning of the activity. Participants were asked to team up freely in groups of 4-6 students. This activity was done during three years, readapting the structure to evaluate impact on students’ learning and exam results. Our statistical analysis showed an increase in final exam grade of students that participated in escape room with a magnitude of 1.03 ± 0.65 points (p < 0.005) compared with those who did not, as well as an increase in global final grade with a magnitude of 1.34 ± 0.83 points (p < 0.005). Additionally, the students that participated showed a significantly higher performance in the final exam regarding cardiovascular (p < 10- 4) and respiratory-related questions (p < 0.005). Furthermore, positive feedback was given by participants on how they found the activity, independently on the impact in grade (as this was done prior to the exam). We conclude this teaching tool should be furtherly assessed in following years in order to implement a peer-topeer teaching structure that can maximize its utility to medical students.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Quantifying the Extent of North American Mammal Extinction Relative to the Pre-Anthropogenic Baseline

Earth has experienced five major extinction events in the past 450 million years. Many scientists suggest we are now witnessing a sixth, driven by human impacts. However, it has been difficult to quantify the real extent of the current extinction episode, either for a given taxonomic group at the continental scale or for the worldwide biota, largely because comparisons of pre-anthropogenic and anthropogenic biodiversity baselines have been unavailable. Here, we compute those baselines for mammals of temperate North America, using a sampling-standardized rich fossil record to reconstruct species-area relationships for a series of time slices ranging from 30 million to 500 years ago. We show that shortly after humans first arrived in North America, mammalian diversity dropped to become at least 15%–42% too low compared to the “normal” diversity baseline that had existed for millions of years. While the Holocene reduction in North American mammal diversity has long been recognized qualitatively, our results provide a quantitative measure that clarifies how significant the diversity reduction actually was. If mass extinctions are defined as loss of at least 75% of species on a global scale, our data suggest that North American mammals had already progressed one-fifth to more than halfway (depending on biogeographic province) towards that benchmark, even before industrialized society began to affect them. Data currently are not available to make similar quantitative estimates for other continents, but qualitative declines in Holocene mammal diversity are also widely recognized in South America, Eurasia, and Australia. Extending our methodology to mammals in these areas, as well as to other taxa where possible, would provide a reasonable way to assess the magnitude of global extinction, the biodiversity impact of extinctions of currently threatened species, and the efficacy of conservation efforts into the future

Data prefetching on in-order processors

Low-power processors have attracted attention due to their energy-efficiency. A large market, such as the mobile one, relies on these processors for this very reason. Even High Performance Computing (HPC) systems are starting to consider low-power processors as a way to achieve exascale performance within 20MW, however, they must meet the right performance/Watt balance. Current low-power processors contain in-order cores, which cannot re-order instructions to avoid data dependency-induced stalls. Whilst this is useful to reduce the chip's total power consumption, it brings several challenges. Due to the evolving performance gap between memory and processor, memory is a significant bottleneck. In-order cores cannot re-order instructions and are memory latency bound, something data prefetching can help alleviate by ensuring data is readily available. In this work, we do an exhaustive analysis of available data prefetching techniques in state-of-The-Art in-order cores. We analyze 5 static prefetchers and 2 dynamic aggressiveness and destination mechanisms applied to 3 data prefetchers on a set of HPC mini-and proxy-Applications, whilst running on in-order processors. We show that next-line prefetching can achieve nearly top performance with a reasonable bandwidth consumption when throttled, whilst neighbor prefetchers have been found to be best, overall.This work has been supported by the RoMoL ERC Advanced Grant (GA 321253), by the European HiPEAC Network of Excellence, by the Spanish Ministry of Science and Innovation (contracts TIN2015-65316-P), by Generalitat de Catalunya (contracts 2014-SGR-1051 and 2014-SGR-1272), by the European Union’s Horizon 2020 research and innovation programme (grant agreements No 671697 and No 779877). M. Moreto has been partially supported by the Spanish Ministry of Economy, Industry and Competitiveness under Ramon y Cajal fellowship number RYC-2016-21104.Peer ReviewedPostprint (author's final draft

A counter-example to a recent version of the Penrose conjecture

By considering suitable axially symmetric slices on the Kruskal spacetime, we construct counterexamples to a recent version of the Penrose inequality in terms of so-called generalized apparent horizons.Comment: 12 pages. Appendix added with technical details. To appear in Classical and Quantum Gravit

The effects of task difficulty on visual search strategy in virtual 3D displays

Analyzing the factors that determine our choice of visual search strategy may shed light on visual behavior in everyday situations. Previous results suggest that increasing task difficulty leads to more systematic search paths. Here we analyze observers&apos; eye movements in an &apos;&apos;easy&apos;&apos; conjunction search task and a &apos;&apos;difficult&apos;&apos; shape search task to study visual search strategies in stereoscopic search displays with virtual depth induced by binocular disparity. Standard eye-movement variables, such as fixation duration and initial saccade latency, as well as new measures proposed here, such as saccadic step size, relative saccadic selectivity, and xÀy target distance, revealed systematic effects on search dynamics in the horizontal-vertical plane throughout the search process. We found that in the &apos;&apos;easy&apos;&apos; task, observers start with the processing of display items in the display center immediately after stimulus onset and subsequently move their gaze outwards, guided by extrafoveally perceived stimulus color. In contrast, the &apos;&apos;difficult&apos;&apos; task induced an initial gaze shift to the upperleft display corner, followed by a systematic left-right and top-down search process. The only consistent depth effect was a trend of initial saccades in the easy task with smallest displays to the items closest to the observer. The results demonstrate the utility of eyemovement analysis for understanding search strategies and provide a first step toward studying search strategies in actual 3D scenarios

Silica-supported Z-selective Ru olefin metathesis catalysts

Under embargo until: 2022-01-17Recently reported thiolate-coordinated ruthenium alkylidene complexes show promise in Z-selective and stereoretentive olefin metathesis reactions. Herein we describe the immobilization of three Ru complexes containing a bulky aryl thiolate on mesostructured silica via surface organometallic chemistry. The applied methodology gives isolated catalytic sites homogeneously distributed on the silica surface. The catalytic results with two model substrates show comparable Z-selectivities to those of the homogeneous counterparts.acceptedVersio