Approaching the quantum critical point in a highly-correlated all-in-all-out antiferromagnet

Continuous quantum phase transition involving all-in–all-out (AIAO) antiferromagnetic order in strongly spin-orbit-coupled 5d compounds could give rise to various exotic electronic phases and strongly-coupled quantum critical phenomena. Here we experimentally trace the AIAO spin order in Sm₂Ir₂O₇ using direct resonant x-ray magnetic diffraction techniques under high pressure. The magnetic order is suppressed at a critical pressure P_c=6.30GPa, while the lattice symmetry remains in the cubic Fd−3m space group across the quantum critical point. Comparing pressure tuning and the chemical series R₂Ir₂O₇ reveals that the approach to the AIAO quantum phase transition is characterized by contrasting evolutions of the pyrochlore lattice constant a and the trigonal distortion surrounding individual Ir moments, which affects the 5d bandwidth and the Ising anisotropy, respectively. We posit that the opposite effects of pressure and chemical tuning lead to spin fluctuations with different Ising and Heisenberg character in the quantum critical region. Finally, the observed low pressure scale of the AIAO quantum phase transition in Sm₂Ir₂O₇ identifies a circumscribed region of P-T space for investigating the putative magnetic Weyl semimetal state

Distance-based consensus models for fuzzy and multiplicative 3 preference relations

This paper proposes a distance-based consensus model for fuzzy preference relations where the weights of fuzzy preference relations are automatically determined. Two indices, an individual to group consensus index (ICI) and a group consensus index (GCI), are introduced. An iterative consensus reaching algorithm is presented and the process terminates until both the ICI and GCI are controlled within predefined thresholds. The model and algorithm are then extended to handle multiplicative preference relations. Finally, two examples are illustrated and comparative analyses demonstrate the effectiveness of the proposed methods

Consistency test and weight generation for additive interval fuzzy preference relations

Some simple yet pragmatic methods of consistency test are developed to check whether an interval fuzzy preference relation is consistent. Based on the definition of additive consistent fuzzy preference relations proposed by Tanino (Fuzzy Sets Syst 12:117–131, 1984), a study is carried out to examine the correspondence between the element and weight vector of a fuzzy preference relation. Then, a revised approach is proposed to obtain priority weights from a fuzzy preference relation. A revised definition is put forward for additive consistent interval fuzzy preference relations. Subsequently, linear programming models are established to generate interval priority weights for additive interval fuzzy preference relations. A practical procedure is proposed to solve group decision problems with additive interval fuzzy preference relations. Theoretic analysis and numerical examples demonstrate that the proposed methods are more accurate than those in Xu and Chen (Eur J Oper Res 184:266–280, 2008b)

ULTRASHORT-PULSE LASER TECHNIQUES FOR UNRAVELING CHEMICAL AND PHYSICAL PROCESSES IN NEXT-GENERATION COMBUSTION SYSTEMS

Ultrashort-pulse, femtosecond (fs)-duration laser techniques are powerful tools for investigating physical and chemical processes in reacting and non-reacting flow systems, providing data with high spatial and temporal resolution. Femtosecond laser pulses are advantages over traditionally used nanosecond laser pulses because of the low average power but high peak power as well as high repetition rate provided by amplified fs lasers. The objective of this thesis research is to use fs laser pulses to investigate mixing processes and also image important intermediate chemical species in combustion systems. The primary work on mixing process studies has been demonstrated using krypton (Kr) as an inert gas tracer. A detailed spectroscopic study was performed to investigate key fluorescence channels followed by the 5p’←←4p, two-photon excitation of Kr using 204.1-nm fs pulses. The experimentally observed spectral line locations agree well with the data in the NIST Atomic Spectra Database in the 750–840-nm emission region, although significant discrepancies in some line strengths were observed. Two-dimensional (2D), two-photon laser-induced fluorescence (TPLIF) images recorded in an unsteady jet demonstrate the potential of using the fs excitation scheme of Kr for mixing and flow diagnostic studies. In the next part of this thesis research, fs-TPLIF was investigated for detecting carbon monoxide (CO) in flames. Interferences from photolytically produced Cv2 Swan-band emissions show a pronounced effect on CO fluorescence signals in fuel-rich, sooting hydrocarbon flames when using CO fs-TPLIF. Therefore, specific spectral filter is required to reduce Cv2 interferences for quantitative concentration measurements in such flames. Interferences from nascent Cv2 originating from hot soot particles could be avoided by using a narrower detection gate width. At elevated pressures, CO fluorescence signal resulting from the fs excitation scheme, decays slower than that resulting from the ns excitation scheme. Comparison of the measured CO fluorescence signal with the calculated CO number density shows a good agreement for both premixed CHv4/air and Cv2Hv4/air flames. Subsequently, fs-TPLIF imaging measurements of CO are also demonstrated in piloted liquid-methanol spray flames. In the final part of this research, fs pulses have been used for planar laser-induced fluorescence (PLIF) measurements of the hydroxyl (OH) radicals in flames. The excitation of the (1,0) vibrational band of the A^2Ʃ^+←X^2Π electronic manifold using single-photon transition scheme has been utilized. The measured OH-LIF signals agree well with the equilibrium calculations in a range of flame conditions. Single-laser-shot, 2D OH-PLIF images recorded at 1-kHz repetition rate in a premixed Cv2Hv4/air jet flame and a turbulent CHv4/Hv2 diffusion flame show the potential of fs-laser pulses for OH imaging measurements in reacting flow systems

Incomplete interval fuzzy preference relations and their applications

This paper investigates incomplete interval fuzzy preference relations. A characterization, which is proposed by Herrera-Viedma et al. (2004), of the additive consistency property of the fuzzy preference relations is extended to a more general case. This property is further generalized to interval fuzzy preference relations (IFPRs) based on additive transitivity. Subsequently, we examine how to characterize IFPR. Using these new characterizations, we propose a method to construct an additive consistent IFPR from a set of n − 1 preference data and an estimation algorithm for acceptable incomplete IFPRs with more known elements. Numerical examples are provided to illustrate the effectiveness and practicality of the solution process

GEOMETRIC CONTROL OF 3D CHROMOSOME ORGANIZATIONS

Ph.DPH.D. IN MECHANOBIOLOGY (NGS

A chi-square method for priority derivation in group decision making with incomplete reciprocal preference relations

This paper proposes a chi-square method (CSM) to obtain a priority vector for group decision making (GDM) problems where decision-makers’ (DMs’) assessment on alternatives is furnished as incomplete reciprocal preference relations with missing values. Relevant theorems and an iterative algorithm about CSM are proposed. Saaty’s consistency ratio concept is adapted to judge whether an incomplete reciprocal preference relation provided by a DM is of acceptable consistency. If its consistency is unacceptable, an algorithm is proposed to repair it until its consistency ratio reaches a satisfactory threshold. The repairing algorithm aims to rectify an inconsistent incomplete reciprocal preference relation to one with acceptable consistency in addition to preserving the initial preference information as much as possible. Finally, four examples are examined to illustrate the applicability and validity of the proposed method, and comparative analyses are provided to show its advantages over existing approaches

Strongly-coupled quantum critical point in an all-in-all-out antiferromagnet

Dimensionality and symmetry play deterministic roles in the laws of Nature. They are important tools to characterize and understand quantum phase transitions, especially in the limit of strong correlations between spin, orbit, charge, and structural degrees of freedom. Using newly-developed, high-pressure resonant x-ray magnetic and charge diffraction techniques, we have discovered a quantum critical point in Cd2Os2O7 as the all-in-all-out (AIAO) antiferromagnetic order is continuously suppressed to zero temperature and, concomitantly, the cubic lattice structure continuously changes from space group Fd-3m to F-43m. Surrounded by three phases of different time reversal and spatial inversion symmetries, the quantum critical region anchors two phase lines of opposite curvature, with striking departures from a mean-field form at high pressure. As spin fluctuations, lattice breathing modes, and quasiparticle excitations interact in the quantum critical region, we argue that they present the necessary components for strongly-coupled quantum criticality in this three-dimensional compound

Global characterization of Artemisia annua glandular trichome transcriptome using 454 pyrosequencing

<p>Abstract</p> <p>Background</p> <p>Glandular trichomes produce a wide variety of commercially important secondary metabolites in many plant species. The most prominent anti-malarial drug artemisinin, a sesquiterpene lactone, is produced in glandular trichomes of <it>Artemisia annua</it>. However, only limited genomic information is currently available in this non-model plant species.</p> <p>Results</p> <p>We present a global characterization of <it>A. annua </it>glandular trichome transcriptome using 454 pyrosequencing. Sequencing runs using two normalized cDNA collections from glandular trichomes yielded 406,044 expressed sequence tags (average length = 210 nucleotides), which assembled into 42,678 contigs and 147,699 singletons. Performing a second sequencing run only increased the number of genes identified by ~30%, indicating that massively parallel pyrosequencing provides deep coverage of the <it>A. annua </it>trichome transcriptome. By BLAST search against the NCBI non-redundant protein database, putative functions were assigned to over 28,573 unigenes, including previously undescribed enzymes likely involved in sesquiterpene biosynthesis. Comparison with ESTs derived from trichome collections of other plant species revealed expressed genes in common functional categories across different plant species. RT-PCR analysis confirmed the expression of selected unigenes and novel transcripts in <it>A. annua </it>glandular trichomes.</p> <p>Conclusion</p> <p>The presence of contigs corresponding to enzymes for terpenoids and flavonoids biosynthesis suggests important metabolic activity in <it>A. annua </it>glandular trichomes. Our comprehensive survey of genes expressed in glandular trichome will facilitate new gene discovery and shed light on the regulatory mechanism of artemisinin metabolism and trichome function in <it>A. annua</it>.</p