We present a combination of thermodynamic and dynamic experimental signatures of a disorder driven dynamic cooperative paramagnet in a 50% site diluted triangular lattice spin-12 system: Y2CuTiO6. ...Magnetic ordering and spin freezing are absent down to 50 mK, far below the Curie-Weiss scale (−θCW) of ∼134 K. We observe scaling collapses of the magnetic field and temperature dependent magnetic heat capacity and magnetization data, respectively, in conformity with expectations from the random singlet physics. Our experiments establish the suppression of any freezing scale, if at all present, by more than 3 orders of magnitude, opening a plethora of interesting possibilities such as disorder stabilized long range quantum entangled ground states.
Dependent phenomena, such as relational, spatial and temporal phenomena, tend to be characterized by local dependence in the sense that units which are close in a well‐defined sense are dependent. In ...contrast with spatial and temporal phenomena, though, relational phenomena tend to lack a natural neighbourhood structure in the sense that it is unknown which units are close and thus dependent. Owing to the challenge of characterizing local dependence and constructing random graph models with local dependence, many conventional exponential family random graph models induce strong dependence and are not amenable to statistical inference. We take first steps to characterize local dependence in random graph models, inspired by the notion of finite neighbourhoods in spatial statistics and M‐dependence in time series, and we show that local dependence endows random graph models with desirable properties which make them amenable to statistical inference. We show that random graph models with local dependence satisfy a natural domain consistency condition which every model should satisfy, but conventional exponential family random graph models do not satisfy. In addition, we establish a central limit theorem for random graph models with local dependence, which suggests that random graph models with local dependence are amenable to statistical inference. We discuss how random graph models with local dependence can be constructed by exploiting either observed or unobserved neighbourhood structure. In the absence of observed neighbourhood structure, we take a Bayesian view and express the uncertainty about the neighbourhood structure by specifying a prior on a set of suitable neighbourhood structures. We present simulation results and applications to two real world networks with ‘ground truth’.
We review and evaluate the methods commonly used in the accounting literature to correct for cross-sectional and time-series dependence. While much of the accounting literature studies settings in ...which variables are cross-sectionally and serially correlated, we find that the extant methods are not robust to both forms of dependence. Contrary to claims in the literature, we find that the Z2 statistic and Newey-West corrected Fama-MacBeth standard errors do not correct for both cross-sectional and time-series dependence. We show that extant methods produce misspecified test statistics in common accounting research settings, and that correcting for both forms of dependence substantially alters inferences reported in the literature. Specifically, several findings in the implied cost of equity capital literature, the cost of debt literature, and the conservatism literature appear not to be robust to the use of well-specified test statistics.
Reducing the enduring vulnerability to relapse is a therapeutic goal in treating drug addiction. Studies with animal models of drug addiction show a marked increase in extrasynaptic glutamate in the ...core subcompartment of the nucleus accumbens (NAcore) during reinstated drug seeking. However, the synaptic mechanisms linking drug-induced changes in extrasynaptic glutamate to relapse are poorly understood. Here, we discovered impaired glutamate elimination in rats extinguished from heroin self-administration that leads to spillover of synaptically released glutamate into the nonsynaptic extracellular space in NAcore and investigated whether restoration of glutamate transport prevented reinstated heroin seeking. Through multiple functional assays of glutamate uptake and analyzing NMDA receptor-mediated currents, we show that heroin self-administration produced long-lasting downregulation of glutamate uptake and surface expression of the transporter GLT-1. This downregulation was associated with spillover of synaptic glutamate to extrasynaptic NMDA receptors within the NAcore. Ceftriaxone restored glutamate uptake and prevented synaptic glutamate spillover and cue-induced heroin seeking. Ceftriaxone-induced inhibition of reinstated heroin seeking was blocked by morpholino-antisense targeting GLT-1 synthesis. These data reveal that the synaptic glutamate spillover in the NAcore results from reduced glutamate transport and is a critical pathophysiological mechanism underling reinstated drug seeking in rats extinguished from heroin self-administration.
This paper investigates the time-frequency dependence and risk connectedness among oil and stock markets in oil-importing and oil-exporting countries using the wavelet coherence and BK frequency ...connectedness method. Those two methods allow us to capture the dynamics of the dependence and risk connectedness over time as well as across different frequency bands (i.e. 1–5 days, 5–22 days, and more than 22 days). The empirical results demonstrate that the dependence structures among oil and stock markets are stronger on long-term scales and the lead-lag associations among oil and stock markets are mixed and time-varying. The total risk spillovers among oil and stock markets are mainly transmitted in the long-run (i.e. more than 22 days). The oil market receives much more risk spillovers from the stock markets in the US, EU, Canada, and Russia. The dynamic risk spillovers at diverse frequency bands are time-varying and heterogeneous. Besides, the major international crisis events, such as the GFC, oil price collapse, and the COVID-19 pandemic have greatly intensified the risk spillover magnitude. The time-frequency dependence and risk spillover analysis can offer great benefits for those energy and financial market participants with multivariate time-horizons in asset allocation and risk management practices.
•The nexus among oil and oil-importing and oil-exporting stock markets are considered.•The wavelet coherence is applied to depict the time-frequency dependence structure.•The frequency connectedness is used to quantify the time-frequency risk spillovers.•The expected-shortfall (ES) is employed in measuring the risk connectedness.•The GFC and COVID-19 pandemic significantly intensified the risk connectedness.
Chain-mapping techniques in combination with the time-dependent density matrix renormalization group are a powerful tool for the simulation of open-system quantum dynamics. For finite-temperature ...environments, however, this approach suffers from an unfavorable algorithmic scaling with increasing temperature. We prove that the system dynamics under thermal environments can be nonperturbatively described by temperature-dependent system-environmental couplings with the initial environment state being in its pure vacuum state, instead of a mixed thermal state. As a consequence, as long as the initial system state is pure, the global system-environment state remains pure at all times. The resulting speed-up and relaxed memory requirements of this approach enable the efficient simulation of open quantum systems interacting with highly structured environments in any temperature range, with applications extending from quantum thermodynamics to quantum effects in mesoscopic systems.
To estimate health outcomes of policies to mitigate the opioid epidemic.
We used dynamic compartmental modeling of US adults, in various pain, opioid use, and opioid addiction health states, to ...project addiction-related deaths, life years, and quality-adjusted life years from 2016 to 2025 for 11 policy responses to the opioid epidemic.
Over 5 years, increasing naloxone availability, promoting needle exchange, expanding medication-assisted addiction treatment, and increasing psychosocial treatment increased life years and quality-adjusted life years and reduced deaths. Other policies reduced opioid prescription supply and related deaths but led some addicted prescription users to switch to heroin use, which increased heroin-related deaths. Over a longer horizon, some such policies may avert enough new addiction to outweigh the harms. No single policy is likely to substantially reduce deaths over 5 to 10 years.
Policies focused on services for addicted people improve population health without harming any groups. Policies that reduce the prescription opioid supply may increase heroin use and reduce quality of life in the short term, but in the long term could generate positive health benefits. A portfolio of interventions will be needed for eventual mitigation.
As a new two-dimensional layered material, black phosphorus (BP) is a very promising material for nanoelectronics and optoelectronics. We use Raman spectroscopy and first-principles theory to ...characterize and understand the low-frequency (LF) interlayer breathing modes (<100 cm–1) in few-layer BP for the first time. Using a laser polarization dependence study and group theory analysis, the breathing modes are assigned to Ag symmetry. Compared to the high-frequency (HF) Raman modes, the LF breathing modes are considerably more sensitive to interlayer coupling and, thus, their frequencies show a stronger dependence on the number of layers. Hence, they constitute an effective means to probe both the crystalline orientation and thickness of few-layer BP. Furthermore, the temperature dependence shows that in the temperature range −150 to 30 °C, the breathing modes have a weak anharmonic behavior, in contrast to the HF Raman modes that exhibit strong anharmonicity.
Chronic opioid exposure is common world-wide, but behavioural performance remains under-investigated. This study aimed to investigate visuospatial memory performance in opioid-exposed and dependent ...clinical populations and its associations with measures of intelligence and cognitive impulsivity.
We recruited 109 participants: (i) patients with a history of opioid dependence due to chronic heroin use (n = 24), (ii) heroin users stabilised on methadone maintenance treatment (n = 29), (iii) participants with a history of chronic pain and prescribed tramadol and codeine (n = 28) and (iv) healthy controls (n = 28). The neuropsychological tasks from the Cambridge Neuropsychological Test Automated Battery included the Delayed Matching to Sample (DMS), Pattern Recognition Memory, Spatial Recognition Memory, Paired Associate Learning, Spatial Span Task, Spatial Working Memory and Cambridge Gambling Task. Pre-morbid general intelligence was assessed using the National Adult Reading Test.
As hypothesised, this study identified the differential effects of chronic heroin and methadone exposures on neuropsychological measures of visuospatial memory (p < 0.01) that were independent of injecting behaviour and dependence status. The study also identified an improvement in DMS performance (specifically at longer delays) when the methadone group was compared with the heroin group and also when the heroin group was stabilised onto methadone. Results identified differential effects of chronic heroin and methadone exposures on various neuropsychological measures of visuospatial memory independently from addiction severity measures, such as injecting behaviour and dependence status.
Variations in the positive temperature dependence of yield stress for L12 intermetallic compounds in pseudo-binary alloys with the composition of Co3(Al, W)–Co3Ti have been investigated. ...Polycrystalline L12 compounds in the pseudo-binary system with a Co3(Al, W) to Co3Ti composition ratio of approximately 1:3 and 1:9 were prepared. The temperature dependence of the yield stress ranging from 293 to 1273 K was determined. The onset temperature for the positive temperature dependence of yield stress for each compound is located between that of Co3(Al, W) and Co3Ti. The activation energies for the positive temperature dependence of these compounds are evaluated to be 47.0 and 43.6 kJmol-1, respectively. The activation energies are also intermediate values between those of Co3(Al, W) and Co3Ti.
The composition dependence of the positive temperature dependence of yield stress is estimated from the physical properties of Co3(Al, W) and Co3Ti. Although the activation energies estimated for the present compounds are slightly different from the experimentally determined values, the temperature dependences of the experimentally determined yield stress are almost represented from the estimated parameters. The composition dependence of the positive temperature dependence of the yield stress can be predicted from the physical properties of the base compounds.
•Variations in the positive temperature dependence of yield stress for Co3(Al, W)–Co3Ti pseudo-binary alloy have been investigated.•Composition dependence of the positive temperature dependence of yield stress is estimated from the physical properties of Co3(Al, W) and Co3Ti.•Composition dependence of the positive temperature dependence of the yield stress can be predicted from the physical properties of the base compounds.
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