Observing different phases for the dynamics of entanglement in an ion trap

The evolution of the entanglement between two oscillators coupled to a common thermal environment is non-trivial. The long time limit has three qualitatively different behaviors (phases) depending on parameters such as the temperature of the bath ({\em Phys. Rev. Lett.} \textbf{100}, 220401). The phases include cases with non-vanishing long-term entanglement, others with a final disentangled state, and situations displaying an infinite sequence of events of disappearance and revival of entanglement. We describe an experiment to realize these different scenarios in an ion trap. The motional degrees of freedom of two ions are used to simulate the system while the coupling to an extra (central) ion, which is continuously laser cooled, is the gateway to a decohering reservoir. The scheme proposed allows for the observation and control of motional entanglement dynamics, and is an example of a class of simulations of quantum open systems in the non-Markovian regime.Comment: 5 pages, 5 figure

Neutrinos from beta processes in a presupernova: probing the isotopic evolution of a massive star

We present a new calculation of the neutrino flux received at Earth from a massive star in the $\sim 24$ hours of evolution prior to its explosion as a supernova (presupernova). Using the stellar evolution code MESA, the neutrino emissivity in each flavor is calculated at many radial zones and time steps. In addition to thermal processes, neutrino production via beta processes is modeled in detail, using a network of 204 isotopes. We find that the total produced $\nu_{e}$ flux has a high energy spectrum tail, at $E \gtrsim 3 - 4$ MeV, which is mostly due to decay and electron capture on isotopes with $A = 50 - 60$. In a tentative window of observability of $E \gtrsim 0.5$ MeV and $t < 2$ hours pre-collapse, the contribution of beta processes to the $\nu_{e}$ flux is at the level of $\sim90\%$ . For a star at $D=1$ kpc distance, a 17 kt liquid scintillator detector would typically observe several tens of events from a presupernova, of which up to $\sim 30\%$ due to beta processes. These processes dominate the signal at a liquid argon detector, thus greatly enhancing its sensitivity to a presupernova.Comment: 14 pages, 5 figure

Decoherence induced by a dynamic spin environment (II): Disentanglement by local system-environment interactions

This article studies the decoherence induced on a system of two qubits by local interactions with a spin chain with nontrivial internal dynamics (governed by an XY Hamiltonian). Special attention is payed to the transition between two limits: one in which both qubits interact with the same site of the chain and another one where they interact with distant sites. The two cases exhibit different behaviours in the weak and strong coupling regimes: when the coupling is weak it is found that decoherence tends to decrease with distance, while for strong coupling the result is the opposite. Also, in the weak coupling case, the long distance limit is rapidly reached, while for strong coupling there is clear evidence of an expected effect: environment-induced interactions between the qubits of the system. A consequence of this is the appearance of quasiperiodic events that can be interpreted as ``sudden deaths'' and ``sudden revivals'' of the entanglement between the qubits, with a time scale related to the distance between them.Comment: 10 pages, 9 figure

On the ergoregion instability in rotating gravastars

The ergoregion instability is known to affect very compact objects that rotate very rapidly and do not possess a horizon. We present here a detailed analysis on the relevance of the ergoregion instability for the viability of gravastars. Expanding on some recent results, we show that not all rotating gravastars are unstable. Rather, stable models can be constructed also with J/M^2 ~ 1, where J and M are the angular momentum and mass of the gravastar, respectively. The genesis of gravastars is still highly speculative and fundamentally unclear if not dubious. Yet, their existence cannot be ruled out by invoking the ergoregion instability. For the same reason, not all ultra-compact astrophysical objects rotating with J/M^2 <~ 1 are to be considered necessarily black holes.Comment: 10 pages, 7 figure

Cannabinoid Receptor Involvement in Stress-Induced Cocaine Reinstatement: Potential Interaction with Noradrenergic Pathways

This study examined the role of endocannabinoid signaling in stress-induced reinstatement of cocaine seeking and explored the interaction between noradrenergic and endocannabinergic systems in the process. A well-validated preclinical model for human relapse, the rodent conditioned place preference assay, was used. Cocaine-induced place preference was established in C57BL/6 mice using injections of 15 mg/kg cocaine. Following extinction of preference for the cocaine-paired environment, reinstatement of place preference was determined following 6 min of swim stress or cocaine injection (15 mg/kg, i.p.). The role of endocannabinoid signaling was studied using the cannabinoid antagonist AM-251 (3 mg/kg, i.p.). Another cohort of mice was tested for reinstatement following administration of the cannabinoid agonist CP 55,940 (10, 20, or 40 μg/kg, i.p.). The alpha-2 adrenergic antagonist BRL-44408 (5 mg/kg, i.p.) with or without CP 55,940 (20 μg/kg) was administered to a third group of mice. We found that: (1) AM-251 blocked forced swim-induced, but not cocaine-induced, reinstatement of cocaine-seeking behavior; (2) the cannabinoid agonist CP 55,940 did not reinstate cocaine-seeking behavior when administered alone but did synergize with a non-reinstating dose of the alpha-2 adrenergic antagonist BRL-44408 to cause reinstatement. These results are consistent with the hypothesis that stress exposure triggers the endogenous activation of CB1 receptors and that activation of the endocannabinoid system is required for the stress-induced relapse of the mice to cocaine seeking. Further, the data suggest that the endocannabinoid system interacts with noradrenergic mechanisms to influence stress-induced reinstatement of cocaine-seeking behavior

Prevalence of the E321G MYH1 variant for immune-mediated myositis and nonexertional rhabdomyolysis in performance subgroups of American Quarter Horses.

BackgroundImmune-mediated myositis (IMM) in American Quarter Horses (QHs) causes acute muscle atrophy and lymphocytic infiltration of myofibers. Recently, an E321G mutation in a highly conserved region of the myosin heavy chain 1 (MYH1) gene was associated with susceptibility to IMM and nonexertional rhabdomyolysis.ObjectivesTo estimate prevalence of the E321G MYH1 variant in the QH breed and performance subgroups.AnimalsThree-hundred seven elite performance QHs and 146 random registered QH controls.MethodsProspective genetic survey. Elite QHs from barrel racing, cutting, halter, racing, reining, Western Pleasure, and working cow disciplines and randomly selected registered QHs were genotyped for the E321G MYH1 variant and allele frequencies were calculated.ResultsThe E321G MYH1 variant allele frequency was 0.034 ± 0.011 in the general QH population (6.8% of individuals in the breed) and the highest among the reining (0.135 ± 0.040; 24.3% of reiners), working cow (0.085 ± 0.031), and halter (0.080 ± 0.027) performance subgroups. The E321G MYH1 variant was present in cutting (0.044 ± 0.022) and Western Pleasure (0.021 ± 0.015) QHs at lower frequency and was not observed in barrel racing or racing QHs.Conclusions and clinical importanceKnowing that reining and working cow QHs have the highest prevalence of the E321G MYH1 variant and that the variant is more prevalent than the alleles for hereditary equine regional dermal asthenia and hyperkalemic periodic paralysis in the general QH population will guide the use of genetic testing for diagnostic and breeding purposes

17β-Estradiol Potentiates the Reinstatement of Cocaine Seeking in Female Rats: Role of the Prelimbic Prefrontal Cortex and Cannabinoid Type-1 Receptors

Clinical observations imply that female cocaine addicts experience enhanced relapse vulnerability compared with males, an effect tied to elevated estrogen phases of the ovarian hormone cycle. Although estrogens can enhance drug-seeking behavior, they do not directly induce reinstatement on their own. To model this phenomenon, we tested whether an estrogen could augment drug-seeking behavior in response to an ordinarily subthreshold reinstatement trigger. Following cocaine self-administration and extinction, female rats were ovariectomized to isolate estrogen effects on reinstatement. Although neither peak proestrus levels of the primary estrogen 17β-estradiol (E2; 10 μg/kg, i.p., 1-h pretreatment) nor a subthreshold cocaine dose (1.25 mg/kg, i.p.) alone were sufficient to reinstate drug-seeking behavior, pretreatment with E2 potentiated reinstatement to the ordinarily subthreshold cocaine dose. Furthermore, E2 microinfusions revealed that E2 (5 μg/0.3 μl, 15-min pretreatment) acts directly within the prelimbic prefrontal cortex (PrL-PFC) to potentiate reinstatement. As E2 has been implicated in endocannabinoid mobilization, which can disinhibit PrL-PFC projection neurons, we investigated whether cannabinoid type-1 receptor (CB1R) activation is necessary for E2 to potentiate reinstatement. The CB1R antagonist AM251 (1 or 3 mg/kg, i.p., 30-min pretreatment) administered prior to E2 and cocaine suppressed reinstatement in a dose-dependent manner. Finally, PrL-PFC AM251 microinfusions (300 ng/side, 15-min pretreatment) also suppressed E2-potentiated reinstatement. Together, these results suggest that E2 can augment reactivity to an ordinarily subthreshold relapse trigger in a PrL-PFC CB1R activation-dependent manner

Using individual tracking data to validate the predictions of species distribution models

The authors would like to thank the College of Life Sciences of Aberdeen University and Marine Scotland Science which funded CP's PhD project. Skate tagging experiments were undertaken as part of Scottish Government project SP004. We thank Ian Burrett for help in catching the fish and the other fishermen and anglers who returned tags. We thank José Manuel Gonzalez-Irusta for extracting and making available the environmental layers used as environmental covariates in the environmental suitability modelling procedure. We also thank Jason Matthiopoulos for insightful suggestions on habitat utilization metrics as well as Stephen C.F. Palmer, and three anonymous reviewers for useful suggestions to improve the clarity and quality of the manuscript.Peer reviewedPostprintPostprintPostprintPostprintPostprin

CB1 Receptor Antagonism Blocks Stress-Potentiated Reinstatement of Cocaine Seeking in Rats

Rationale Under some conditions, stress, rather than directly triggering cocaine seeking, potentiates reinstatement to other stimuli, including a subthreshold cocaine dose. The mechanisms responsible for stress-potentiated reinstatement are not well defined. Endocannabinoid signaling is increased by stress and regulates synaptic transmission in brain regions implicated in motivated behavior. Objectives The objective of this study was to test the hypothesis that cannabinoid type 1 receptor (CB1R) signaling is required for stress-potentiated reinstatement of cocaine seeking in rats. Methods Following i.v. cocaine self-administration (2 h access/day) and extinction in male rats, footshock stress alone does not reinstate cocaine seeking but reinstatement is observed when footshock is followed by an injection of an otherwise subthreshold dose of cocaine (2.5 mg/kg, i.p.). CB1R involvement was tested by systemic administration of the CB1R antagonist AM251 (0, 1, or 3 mg/kg, i.p.) prior to testing for stress-potentiated reinstatement. Results Stress-potentiated reinstatement was blocked by both 1 and 3 mg/kg AM251. By contrast, AM251 only attenuated food-reinforced lever pressing at the higher dose (i.e., 3 mg/kg) and did not affect locomotor activity at either dose tested. Neither high-dose cocaine-primed reinstatement (10 mg/kg, i.p.) nor footshock stress-triggered reinstatement following long-access cocaine self-administration (6 h access/day) was affected by AM251 pretreatment. Footshock stress increased concentrations of both endocannabinoids, N-arachidonylethanolamine and 2-arachidonoylglycerol, in regions of the prefrontal cortex. Conclusions These findings demonstrate that footshock stress increases prefrontal cortical endocannabinoids and stress-potentiated reinstatement is CB1R-dependent, suggesting that CB1R is a potential therapeutic target for relapse prevention, particularly in individuals whose cocaine use is stress-related