We introduce a complex-plane generalization of the consecutive level-spacing ratio distribution used to distinguish regular from chaotic quantum spectra. Our approach features the distribution of ...complex-valued ratios between nearest- and next-to-nearest-neighbor spacings. We show that this quantity can successfully detect the chaotic or regular nature of complex-valued spectra, which is done in two steps. First, we show that, if eigenvalues are uncorrelated, the distribution of complex spacing ratios is flat within the unit circle, whereas random matrices show a strong angular dependence in addition to the usual level repulsion. The universal fluctuations of Gaussian unitary and Ginibre unitary universality classes in the large-matrix-size limit are shown to be well described by Wigner-like surmises for small-size matrices with eigenvalues on the circle and on the two-torus, respectively. To study the latter case, we introduce the toric unitary ensemble, characterized by a flat joint eigenvalue distribution on the two-torus. Second, we study different physical situations where non-Hermitian matrices arise: dissipative quantum systems described by a Lindbladian, nonunitary quantum dynamics described by non-Hermitian Hamiltonians, and classical stochastic processes. We show that known integrable models have a flat distribution of complex spacing ratios, whereas generic cases, expected to be chaotic, conform to random matrix theory predictions. Specifically, we are able to clearly distinguish chaotic from integrable dynamics in boundary-driven dissipative spin-chain Liouvillians and in the classical asymmetric simple exclusion process and to differentiate localized from delocalized regimes in a non-Hermitian disordered many-body system.
Polymetallic nodule mining at abyssal depths in the Clarion Clipperton Fracture Zone (Eastern Central Pacific) will impact one of the most remote and least known environments on Earth. Since vast ...areas are being targeted by concession holders for future mining, large-scale effects of these activities are expected. Hence, insight into the fauna associated with nodules is crucial to support effective environmental management. In this study video surveys were used to compare the epifauna from sites with contrasting nodule coverage in four license areas. Results showed that epifaunal densities are more than two times higher at dense nodule coverage (>25 versus ≤10 individuals per 100 m(2)), and that taxa such as alcyonacean and antipatharian corals are virtually absent from nodule-free areas. Furthermore, surveys conducted along tracks from trawling or experimental mining simulations up to 37 years old, suggest that the removal of epifauna is almost complete and that its full recovery is slow. By highlighting the importance of nodules for the epifaunal biodiversity of this abyssal area, we urge for cautious consideration of the criteria for determining future preservation zones.
We study generic open quantum systems with Markovian dissipation, focusing on a class of stochastic Liouvillian operators of Lindblad form with independent random dissipation channels (jump ...operators) and a random Hamiltonian. We establish that the global spectral features, the spectral gap, and the steady-state properties follow three different regimes as a function of the dissipation strength, whose boundaries depend on the particular quantity. Within each regime, we determine the scaling exponents with the dissipation strength and system size. We find that, for two or more dissipation channels, the spectral gap increases with the system size. The spectral distribution of the steady state is Poissonian at low dissipation strength and conforms to that of a random matrix once the dissipation is sufficiently strong. Our results can help to understand the long-time dynamics and steady-state properties of generic dissipative systems.
The submarine exploration using robots has been increasing in recent years. The automation of tasks such as monitoring, inspection, and underwater maintenance requires the understanding of the ...robot's environment. The object recognition in the scene is becoming a critical issue for these systems. On this work, an underwater object classification pipeline applied in acoustic images acquired by Forward-Looking Sonar (FLS) are studied. The object segmentation combines thresholding, connected pixels searching and peak of intensity analyzing techniques. The object descriptor extract intensity and geometric features of the detected objects. A comparison between the Support Vector Machine, K-Nearest Neighbors, and Random Trees classifiers are presented. An open-source tool was developed to annotate and classify the objects and evaluate their classification performance. The proposed method efficiently segments and classifies the structures in the scene using a real dataset acquired by an underwater vehicle in a harbor area. Experimental results demonstrate the robustness and accuracy of the method described in this paper.
To assess the efficacy of golimumab in combination with methotrexate (MTX) versus MTX monotherapy in psoriatic arthritis (PsA) dactylitis.
Multicentre, investigator-initiated, randomised, ...double-blind, placebo-controlled, parallel-design phase 3b trial in 11 Portuguese rheumatology centres. Patients with PsA along with active dactylitis and naive to MTX and biologic disease-modifying antirheumatic drugs (bDMARDs) were randomly assigned to golimumab or placebo, both in combination with MTX. The primary endpoint was Dactylitis Severity Score (DSS) change from baseline to week 24. Key secondary endpoints included DSS and Leeds Dactylitis Index (LDI) response, and changes from baseline in the LDI and MRI dactylitis score. Analysis was by intention-to-treat for the primary endpoint.
Twenty-one patients received golimumab plus MTX and 23 MTX monotherapy for 24 weeks. One patient from each arm discontinued. Patient inclusion was halted at 50% planned recruitment due to a favourable interim analysis. Median baseline DSS was 6 in both arms. By week 24, patients treated with golimumab plus MTX exhibited significantly greater improvements in DSS relative to MTX monotherapy (median change of 5 vs 2 points, respectively; p=0.026). In the golimumab plus MTX arm, significantly higher proportions of patients achieved at least 50% or 70% improvement in DSS and 20%, 50% or 70% improvement in LDI in comparison to MTX monotherapy.
The combination of golimumab and MTX as first-line bDMARD therapy is superior to MTX monotherapy for the treatment of PsA dactylitis.
NCT02065713.
The increasing availability of short‐read whole genome sequencing (WGS) provides unprecedented opportunities to study ecological and evolutionary processes. Although loci of interest can be extracted ...from WGS data and combined with target sequence data, this requires suitable bioinformatic workflows. Here, we test different assembly and locus extraction strategies and implement them into secapr, a pipeline that processes short‐read data into multilocus alignments for phylogenetics and molecular ecology analyses. We integrate the processing of data from low‐coverage WGS (<30×) and target sequence capture into a flexible framework, while optimizing de novo contig assembly and loci extraction. Specifically, we test different assembly strategies by contrasting their ability to recover loci from targeted butterfly protein‐coding genes, using four data sets: a WGS data set across different average coverages (10×, 5× and 2×) and a data set for which these loci were enriched prior to sequencing via target sequence capture. Using the resulting de novo contigs, we account for potential errors within contigs and infer phylogenetic trees to evaluate the ability of each assembly strategy to recover species relationships. We demonstrate that choosing multiple sizes of kmer simultaneously for assembly results in the highest yield of extracted loci from de novo assembled contigs, while data sets derived from sequencing read depths as low as 5× recovers the expected species relationships in phylogenetic trees. By making the tested assembly approaches available in the secapr pipeline, we hope to inspire future studies to incorporate complementary data and make an informed choice on the optimal assembly strategy.
In Australia, the stress levels have increased over the years, impacting on the physical and mental health of the general population. The aim of the present study was to evaluate the validity and ...reliability of the PSS-14 in an Australian population.
The PSS-14 was applied to a large national sample comprising 3857 Australians in the population-based cross-sectional study Australia's National Survey of Adult Oral Health 2004-2006. The psychometric properties analyzed with the Rasch model and Graphical Log-linear Rasch models were: model fit, item fit, local dependence, differential item functioning, unidimensionality, reliability, targeting and criterion validity.
The PSS-14 did not fit the pure RM (χ2 (55) = 3828.3, p = < 0.001) and the unidimensionality of the whole scale was rejected (p = < 0.001). The Perceived Stress (χ2 (27) = 1409.7, p = < 0.001) and Perceived Control (χ2 (27) = 713.4, p = < 0.001) subscales did not fit the pure RM. After the deletion of two items, the Perceived Stress subscale (χ2 (96) = 94.4, p = 0.440) fitted a GLLRM, while the Perceived Control scale (χ2 (55) = 62.50, p = 0.224) fitted a GLLRM after the exclusion of four misfitting items.
The Perceived Stress subscale displayed adequate psychometric properties after the deletion of two items; however, the majority of problems centered around the Perceived Control subscale. The presence of differential item functioning among four items indicates that adjustment of total scores is required to avoid measurement bias. Recommendations for future applications in Australia are provided.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Human evolution is widely thought to have involved a particular expansion of prefrontal cortex. This popular notion has recently been challenged, although controversies remain. Here we show that the ...prefrontal region of both human and nonhuman primates holds about 8% of cortical neurons, with no clear difference across humans and other primates in the distribution of cortical neurons or white matter cells along the anteroposterior axis. Further, we find that the volumes of human prefrontal gray and white matter match the expected volumes for the number of neurons in the gray matter and for the number of other cells in the white matter compared with other primate species. These results indicate that prefrontal cortical expansion in human evolution happened along the same allometric trajectory as for other primate species, without modification of the distribution of neurons across its surface or of the volume of the underlying white matter. We thus propose that the most distinctive feature of the human prefrontal cortex is its absolute number of neurons, not its relative volume.
In Australia, despite social support increasingly being reported as playing an important role in influencing health outcomes of Aboriginal and Torres Strait Islanders, measures of social support have ...not yet been validated for Aboriginal people. The current study aimed to evaluate the validity and reliability of the Social Support Scale in an Aboriginal and/or Torres Strait Islander population. The Social Support Scale (SSS) is a 4-item psychological instrument that was designed to evaluate four social support functions, instrumental, informational, emotional and appraisal support. Data included participants from two different samples: (1) Teeth Talk Study (n = 317), an oral-health randomized controlled trial (RCT) conducted with Aboriginal adults; and (2) the South Australian Aboriginal Birth Cohort Study (n = 367), a prospective longitudinal birth cohort study in which pregnant Aboriginal women were interviewed at baseline. The SSS psychometric properties were examined with Graphical Loglinear Rasch Models (GLLRM). The overall fit to a GLLRM was established (χ2(96)sample1 = 52.7, p = 0.06; χ2(25)sample2 = 22.2, p = 0.62) after accounting for local dependence between items 3 and 4. Item 2 displayed differential item functioning by employment status in Sample 1. Regarding dimensionality, the SSS was unidimensional in both samples (γobs1 = 0.80; γexp1 = 0.78, p = 0.65; γobs2 = 0.75, γexp2 = 0.77, p = 0.16). The instrument also displayed good reliability (Rsample1 = 0.82, Rsample2 = 0.84). Despite a few identified limitations (such as poor targeting), the findings indicated that the SSS is a promising instrument to provide culturally-valid and reliable measurement of social support among Aboriginal and/or Torres Strait Islander adults. Future studies should further investigate the instrument psychometric properties in other Aboriginal samples and the development and inclusion of culturally-sensitive items are also recommended.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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