The Computational Complexity of Propositional Cirquent Calculus

Introduced in 2006 by Japaridze, cirquent calculus is a refinement of sequent calculus. The advent of cirquent calculus arose from the need for a deductive system with a more explicit ability to reason about resources. Unlike the more traditional proof-theoretic approaches that manipulate tree-like objects (formulas, sequents, etc.), cirquent calculus is based on circuit-style structures called cirquents, in which different "peer" (sibling, cousin, etc.) substructures may share components. It is this resource sharing mechanism to which cirquent calculus owes its novelty (and its virtues). From its inception, cirquent calculus has been paired with an abstract resource semantics. This semantics allows for reasoning about the interaction between a resource provider and a resource user, where resources are understood in the their most general and intuitive sense. Interpreting resources in a more restricted computational sense has made cirquent calculus instrumental in axiomatizing various fundamental fragments of Computability Logic, a formal theory of (interactive) computability. The so-called "classical" rules of cirquent calculus, in the absence of the particularly troublesome contraction rule, produce a sound and complete system CL5 for Computability Logic. In this paper, we investigate the computational complexity of CL5, showing it is $\Sigma_2^p$-complete. We also show that CL5 without the duplication rule has polynomial size proofs and is NP-complete

Analysis of randomized security protocols

Formal analysis has a long and successful track record in the automated verification of security protocols. Techniques in this domain have converged around modeling protocols as non-deterministic processes that interact asynchronously through an adversarial environment controlled by a Dolev-Yao attacker. There are, however, a large class of protocols whose correctness relies on an explicit ability to model and reason about randomness. Lying at the heart of many widely adopted systems for anonymous communication, these protocols have so-far eluded automated verification techniques. The present work overcomes this long standing obstacle, providing the first framework analyzing randomized security protocols against Dolev-Yao attackers. In this formalism, we present algorithms for model checking safety and indistinguishability properties of randomized security protocols. Our techniques are implemented in the Stochastic Protocol ANalyzer (SPAN) and evaluated on a new suite of benchmarks. Our benchmark examples include a brand new class of protocols that have never been subject of formal (symbolic) verification, including: mix-networks, dinning cryptographers networks, and several electronic voting protocols. During our analysis, we uncover previously unknown vulnerabilities in two popular electronic voting protocols from the literature. The high overhead associated with verifying security protocols, in conjunction with the fact that protocols are rarely run in isolation, has created a demand for modular verification techniques. In our protocol analysis framework, we give a series of composition results for safety and indistinguishability properties of randomized security protocols. Finally, we study the model checking problem for the probabilistic objects that lie at the heart of our protocol semantics. In particular, we present a novel technique that allows for the precise verification of probabilistic computation tree logic (PCTL) properties of discrete time Markov chains (DTMCs) and Markov decision processes (MDPs) at scale. Although our motivation comes from protocol analysis, the techniques further verification capabilities in many application areas

Nrf2 expression modifies influenza A entry and replication in nasal epithelial cells

Influenza infection is a major cause of morbidity and mortality worldwide, especially during pandemics outbreaks. Emerging data indicate that phase II antioxidant enzyme pathways could play a role in virus-associated inflammation and immune clearance. While Nrf2-dependent gene expression is known to modify inflammation, a mechanistic role in viral susceptibility and clearance has yet to be elucidated. Therefore, we utilized differentiated human nasal epithelial cells (NEC) and an enzymatic virus-like particle entry assay, to examine the role Nrf2-dependent gene expression has on viral entry and replication. Herein, lentiviral vectors that express Nrf2-specific short hairpin (sh)-RNA effectively decreased both Nrf2 mRNA and Nrf2 protein expression in transduced human NEC from healthy volunteers. Nrf2 knockdown correlated with a significant increase in influenza virus entry and replication. Conversely, supplementation with the potent Nrf2 activators sulforaphane (SFN) and epigallocatechin gallate (EGCG) significantly decreased viral entry and replication. The suppressive effects of EGCG on viral replication were abolished in cells with knocked down Nrf2 expression, suggesting a causal relationship between EGCG-induced activation of Nrf2 and ability to protect against viral infection. Interestingly, the induction of Nrf2 via nutritional supplements SFN and EGCG, increased antiviral mediators/responses; RIG-I, IFN-β, and MxA at baseline in the absence of infection. Our data indicate that there is an inverse relationship between the levels of Nrf2 expression, and viral entry/replication. We also demonstrate that supplementation with Nrf2-activating antioxidants inhibit viral replication in human NEC, which may prove to be an attractive therapeutic intervention. Taken together, these data indicate potential mechanisms by which Nrf2-dependent gene expression regulates susceptibility to influenza in human epithelial cells

Galaxy And Mass Assembly (GAMA) : stellar mass functions by Hubble type

This work was supported by the Austrian Science Foundation FWF under grant P23946. AWG was supported under the Australian Research Council's funding scheme FT110100263.We present an estimate of the galaxy stellar mass function and its division by morphological type in the local (0.025 < z < 0.06) Universe. Adopting robust morphological classifications as previously presented (Kelvin et al.) for a sample of 3727 galaxies taken from the Galaxy And Mass Assembly survey, we define a local volume and stellar mass limited sub-sample of 2711 galaxies to a lower stellar mass limit of M = 109.0 MΘ. We confirm that the galaxy stellar mass function is well described by a double-Schechter function given by Μ* = 1010.64 MΘ, α1 = 0.43, φ1* = 4.18 dex-1 Mpc-3, α2 = −1.50 and φ2* = 0.74 dex-1 Mpc-3. The constituent morphological-type stellar mass functions are well sampled above our lower stellar mass limit, excepting the faint little blue spheroid population of galaxies. We find approximately 71-4+3 per cent of the stellar mass in the local Universe is found within spheroid-dominated galaxies; ellipticals and S0-Sas. The remaining 29-3+4 per cent falls predominantly within late-type disc-dominated systems, Sab-Scds and Sd-Irrs. Adopting reasonable bulge-to-total ratios implies that approximately half the stellar mass today resides in spheroidal structures, and half in disc structures. Within this local sample, we find approximate stellar mass proportions for E : S0-Sa : Sab-Scd : Sd-Irr of 34 : 37 : 24 :5.Publisher PDFPeer reviewe

Total Neoadjuvant Therapy With Short-Course Radiation: US Experience of a Neoadjuvant Rectal Cancer Therapy

BACKGROUND: Short-course radiation followed by chemotherapy as total neoadjuvant therapy has been investigated primarily in Europe and Australia with increasing global acceptance. There are limited data on this regimen\u27s use in the United States, however, potentially delaying implementation. OBJECTIVE: This study aimed to compare clinical performance and oncologic outcomes of 2 rectal cancer neoadjuvant treatment modalities: short-course total neoadjuvant therapy versus standard chemoradiation. DESIGN: This is a retrospective cohort study. SETTING: This study was performed at a National Cancer Institute-designated cancer center. PATIENTS: A total of 413 patients had locally advanced rectal cancers diagnosed from June 2009 to May 2018 and received either short-course total neoadjuvant therapy or standard chemoradiation. INTERVENTIONS: There were 187 patients treated with short-course total neoadjuvant therapy (5 × 5 Gy radiation followed by consolidation oxaliplatin-based chemotherapy) compared with 226 chemoradiation recipients (approximately 50.4 Gy radiation in 28 fractions with concurrent fluorouracil equivalent). MAIN OUTCOME MEASURES: Primary end points were tumor downstaging, measured by complete response and low neoadjuvant rectal score rates, and progression-free survival. Secondary analyses included treatment characteristics and completion, sphincter preservation, and recurrence rates. RESULTS: Short-course total neoadjuvant therapy was associated with higher rates of complete response (26.2% vs 17.3%; p = 0.03) and low neoadjuvant rectal scores (40.1% vs 25.7%; p \u3c 0.01) despite a higher burden of node-positive disease (78.6% vs 68.9%; p = 0.03). Short-course recipients also completed trimodal treatment more frequently (88.4% vs 50.4%; p \u3c 0.01) and had fewer months with temporary stomas (4.8 vs 7.0; p \u3c 0.01). Both regimens achieved comparable local control (local recurrence: 2.7% short-course total neoadjuvant therapy vs 2.2% chemoradiation, p = 0.76) and 2-year progression-free survival (88.2% short-course total neoadjuvant therapy (95% CI, 82.9-93.5) vs 85.6% chemoradiation (95% CI, 80.5-90.7)). LIMITATIONS: Retrospective design, unbalanced disease severity, and variable dosing of neoadjuvant consolidation chemotherapy were limitations of this study. CONCLUSIONS: Short-course total neoadjuvant therapy was associated with improved downstaging and similar progression-free survival compared with chemoradiation. These results were achieved with shortened radiation courses, improved treatment completion, and less time with diverting ostomies. Short-course total neoadjuvant therapy is an optimal regimen for locally advanced rectal cancer

Galaxy And Mass Assembly (GAMA) : the large-scale structure of galaxies and comparison to mock universes

MA acknowledges funding from the University of St Andrews and the International Centre for Radio Astronomy Research. ASGR is supported by funding from a UWA Fellowship. PN acknowledges the support of the Royal Society through the award of a University Research Fellowship and the European Research Council, through receipt of a Starting Grant (DEGAS-259586). MJIB acknowledges the financial support of the Australian Research Council Future Fellowship 100100280. TMR acknowledges support from a European Research Council Starting Grant (DEGAS-259586).From a volume-limited sample of 45 542 galaxies and 6000 groups with z ≤ 0.213, we use an adapted minimal spanning tree algorithm to identify and classify large-scale structures within the Galaxy And Mass Assembly (GAMA) survey. Using galaxy groups, we identify 643 filaments across the three equatorial GAMA fields that span up to 200 h−1 Mpc in length, each with an average of eight groups within them. By analysing galaxies not belonging to groups, we identify a secondary population of smaller coherent structures composed entirely of galaxies, dubbed ‘tendrils’ that appear to link filaments together, or penetrate into voids, generally measuring around 10 h−1 Mpc in length and containing on average six galaxies. Finally, we are also able to identify a population of isolated void galaxies. By running this algorithm on GAMA mock galaxy catalogues, we compare the characteristics of large-scale structure between observed and mock data, finding that mock filaments reproduce observed ones extremely well. This provides a probe of higher order distribution statistics not captured by the popularly used two-point correlation function.Peer reviewe

The shared socio-economic pathway (SSP) greenhouse gas concentrations and their extensions to 2500

Anthropogenic increases in atmospheric greenhouse gas concentrations are the main driver of current and future climate change. The integrated assessment community has quantified anthropogenic emissions for the shared socio-economic pathway (SSP) scenarios, each of which represents a different future socio-economic projection and political environment. Here, we provide the greenhouse gas concentrations for these SSP scenarios – using the reduced-complexity climate–carbon-cycle model MAGICC7.0. We extend historical, observationally based concentration data with SSP concentration projections from 2015 to 2500 for 43 greenhouse gases with monthly and latitudinal resolution. CO2 concentrations by 2100 range from 393 to 1135 ppm for the lowest (SSP1-1.9) and highest (SSP5-8.5) emission scenarios, respectively. We also provide the concentration extensions beyond 2100 based on assumptions regarding the trajectories of fossil fuels and land use change emissions, net negative emissions, and the fraction of non-CO2 emissions. By 2150, CO2 concentrations in the lowest emission scenario are approximately 350 ppm and approximately plateau at that level until 2500, whereas the highest fossil-fuel-driven scenario projects CO2 concentrations of 1737 ppm and reaches concentrations beyond 2000 ppm by 2250. We estimate that the share of CO2 in the total radiative forcing contribution of all considered 43 long-lived greenhouse gases increases from 66 % for the present day to roughly 68 % to 85 % by the time of maximum forcing in the 21st century. For this estimation, we updated simple radiative forcing parameterizations that reflect the Oslo Line-By-Line model results. In comparison to the representative concentration pathways (RCPs), the five main SSPs (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) are more evenly spaced and extend to lower 2100 radiative forcing and temperatures. Performing two pairs of six-member historical ensembles with CESM1.2.2, we estimate the effect on surface air temperatures of applying latitudinally and seasonally resolved GHG concentrations. We find that the ensemble differences in the March–April–May (MAM) season provide a regional warming in higher northern latitudes of up to 0.4 K over the historical period, latitudinally averaged of about 0.1 K, which we estimate to be comparable to the upper bound (∼5 % level) of natural variability. In comparison to the comparatively straight line of the last 2000 years, the greenhouse gas concentrations since the onset of the industrial period and this studies' projections over the next 100 to 500 years unequivocally depict a “hockey-stick” upwards shape. The SSP concentration time series derived in this study provide a harmonized set of input assumptions for long-term climate science analysis; they also provide an indication of the wide set of futures that societal developments and policy implementations can lead to – ranging from multiple degrees of future warming on the one side to approximately 1.5 ∘C warming on the other

Galaxy And Mass Assembly (GAMA): Linking star formation histories and stellar mass growth

WWe present evidence for stochastic star formation histories in low-mass (M* <1010M⊙) galaxies from observations within the Galaxy And Mass Assembly (GAMA) survey. For ̃73 000 galaxies between 0.05 < z < 0.32, we calculate star formation rate