Reasoning about Cognitive Trust in Stochastic Multiagent Systems

We consider the setting of stochastic multiagent systems modelled as stochastic multiplayer games and formulate an automated verification framework for quantifying and reasoning about agents’ trust. To capture human trust, we work with a cognitive notion of trust defined as a subjective evaluation that agent A makes about agent B’s ability to complete a task, which in turn may lead to a decision by A to rely on B. We propose a probabilistic rational temporal logic PRTL*, which extends the probabilistic computation tree logic PCTL* with reasoning about mental attitudes (beliefs, goals, and intentions) and includes novel operators that can express concepts of social trust such as competence, disposition, and dependence. The logic can express, for example, that “agent A will eventually trust agent B with probability at least p that B will behave in a way that ensures the successful completion of a given task.” We study the complexity of the automated verification problem and, while the general problem is undecidable, we identify restrictions on the logic and the system that result in decidable, or even tractable, subproblems

A quantitative trait locus for the number of days from sowing to seedling emergence in maize

Quantitative trait locus (QTL) mapping provides useful information for breeding programs since it allows the estimation of genomic locations and genetic effects of chromosomal regions related to the expression of quantitative traits. The number of days from sowing to seedling emergence (NDSSE) is an important agronomic trait in a maize (Zea mays L.) breeding project which is related to yield. To determine its genetic basis, a recombinant inbred line (RIL) population and two nitrogen (N) regimes were used to detect the QTLs associated with NDSSE; as a result, one QTL was identified under high N regime, on chromosome 9, which could explain 6.20% of phenotypic variance and a decrease of 0.18 of NDSSE due to an additive effect. These results are beneficial for understanding the genetic basis of NDSSE in maize breeding project.Key words: Maize (Zea mays L.), quantitative trait locus, recombinant inbred line, nitrogen

Slow cooling and efficient extraction of C-exciton hot carriers in MoS2 monolayer

In emerging optoelectronic applications, such as water photolysis, exciton fission and novel photovoltaics involving low-dimensional nanomaterials, hot-carrier relaxation and extraction mechanisms play an indispensable and intriguing role in their photo-electron conversion processes. Two-dimensional transition metal dichalcogenides have attracted much attention in above fields recently; however, insight into the relaxation mechanism of hot electron-hole pairs in the band nesting region denoted as C-excitons, remains elusive. Using MoS2 monolayers as a model two-dimensional transition metal dichalcogenide system, here we report a slower hot-carrier cooling for C-excitons, in comparison with band-edge excitons. We deduce that this effect arises from the favourable band alignment and transient excited-state Coulomb environment, rather than solely on quantum confinement in two-dimension systems. We identify the screening-sensitive bandgap renormalization for MoS2 monolayer/graphene heterostructures, and confirm the initial hot-carrier extraction for the C-exciton state with an unprecedented efficiency of 80%, accompanied by a twofold reduction in the exciton binding energy

Cassiterite oxygen isotopes in magmatic-hydrothermal systems: in situ microanalysis, fractionation factor, and applications

Tin and tungsten are important metals for the industrializing society. Deciphering the origin and evolution of hydrothermal fluids responsible for their formation is critical to underpin genetic models of ore formation. Traditional approaches obtain isotopic information mainly from bulk analysis of both ore and gangue minerals, or less frequently from in situ analysis of gangue minerals, which either bear inherited complexities and uncertainties or are indirect constraints. Hence, directly obtaining isotopic information from ore minerals such as cassiterite by in situ techniques is warranted. However, this has been hampered by challenges from both analytical and applicational aspects. In this study, we first demonstrate a lack of crystallographic orientation effects during cassiterite ion microprobe oxygen isotope analysis. Along with our newly developed matrix-matched reference material, the Yongde-Cst, which has a recommended δ18O value of 1.36 ± 0.16‰ (VSMOW) as defined by gas source isotope ratio mass spectrometry, in situ oxygen isotope analysis of cassiterite now is possible. We further refine the oxygen isotope fractionation (1000 ln α) for quartz-cassiterite by first-principles calculations, which is given by the equation of 1.259 × 106/T2 + 8.15 × 103/T − 4.72 (T is temperature in Kelvin). The 1000 ln α for quartz-cassiterite has a sensitive response to temperature, and makes cassiterite-quartz an excellent mineral pair in oxygen isotope thermometry, as described by the equation of T (℃) = 2427 × (δ18Oqtz − δ18Ocst)−0.4326 − 492.4. Using the well-established 1000 ln α of quartz-water, 1000 ln α of cassiterite-water is derived as 2.941 × 106/T2 − 11.45 × 103/T + 4.72 (T in Kelvin), which shows a weak response to temperature. This makes cassiterite an ideal mineral from which to derive δ18O of fluids as robust temperature estimates are no longer a prerequisite. We have applied oxygen isotope analysis to cassiterite samples from six Sn(-W) deposits in China. The results show considerable variability in δ18O values both within a single deposit and among studied deposits. Combining the δ18O of cassiterite samples and the equilibrium oxygen isotope fractionation, we find that the δ18O values of ore-forming fluids show a strong magmatic affinity with variable but mostly no to low degree involvements (~0-10%) of meteoric water, hence our results invite a reassessment on the extent and role of meteoric water in Sn-W mineralization. This study demonstrates that in situ oxygen isotope analysis of cassiterite is a promising tool to refine sources of ore-forming fluids, and to decode hydrothermal dynamics controlling tin and tungsten mineralization

The optical microscopy with virtual image breaks a record: 50-nm resolution imaging is demonstrated

We demonstrate a new 'microsphere nanoscope' that uses ordinary SiO2 microspheres as superlenses to create a virtual image of the object in near field. The magnified virtual image greatly overcomes the diffraction limit. We are able to resolve clearly 50-nm objects under a standard white light source in both transmission and reflection modes. The resolution achieved for white light opens a new opportunity to image viruses, DNA and molecules in real time

Initial Growth of Single-Crystalline Nanowires: From 3D Nucleation to 2D Growth

The initial growth stage of the single-crystalline Sb and Co nanowires with preferential orientation was studied, which were synthesized in porous anodic alumina membranes by the pulsed electrodeposition technique. It was revealed that the initial growth of the nanowires is a three-dimensional nucleation process, and then gradually transforms to two-dimensional growth via progressive nucleation mechanism, which resulting in a structure transition from polycrystalline to single crystalline. The competition among the nuclei inside the nanoscaled-confined channel and the growth kinetics is responsible for the structure transition of the initial grown nanowires

Cyclooxygenase-2 Induction by Arsenite through the IKKβ/NFκB Pathway Exerts an Antiapoptotic Effect in Mouse Epidermal Cl41 cells

BACKGROUND: Arsenic contamination has become a major public health concern worldwide. Epidemiologic data show that long-term arsenic exposure results in the risk of skin cancer. However, the mechanisms underlying carcinogenic effects of arsenite on skin remain to be studied. OBJECTIVES: In the present study we evaluated cyclooxygenase-2 (COX-2) expression, the signaling pathways leading to COX-2 induction, and its antiapoptotic function in the response to arsenite exposure in mouse epidermal JB6 Cl41 cells. METHODS: We used the luciferase reporter assay and Western blots to determine COX-2 induction by arsenite. We utilized dominant negative mutant, genetic knockout, gene knockdown, and gene overexpression approaches to elucidate the signaling pathway involved in COX-2 induction and its protective effect on cell apoptosis. RESULTS: The induction of COX-2 by arsenite was inhibited in Cl41 cells transfected with IKKβ-KM, a dominant mutant inhibitor of kβ (Ikβ) kinase (IKKβ), and in IKKβ-knockout (IKKβ(−/−)) mouse embryonic fibroblasts (MEFs). IKKβ/nuclear factor κB (NFκB) pathway-mediated COX-2 induction exerted an antiapoptotic effect on the cells exposed to arsenite because cell apoptosis was significantly enhanced in the Cl41 cells transfected with IKKβ-KM or COX-2 small interference RNA (siCOX-2). In addition, IKKβ(−/−) MEFs stably transfected with COX-2 showed more resistance to arsenite-induced apoptosis compared with the same control vector–transfected cells. CONCLUSIONS: These results demonstrate that arsenite exposure can induce COX-2 expression through the IKKβ/NFκB pathway, which thereby exerts an antiapoptotic effect in response to arsenite. In light of the importance of apoptosis evasion during carcinogenesis, we anticipate that COX-2 induction may be at least partially responsible for the carcinogenic effect of arsenite on skin