Nuclear spin driven quantum relaxation in LiY_0.998Ho_0.002F_4

Staircase hysteresis loops of the magnetization of a LiY_0.998Ho_0.002F_4 single crystal are observed at subkelvin temperatures and low field sweep rates. This behavior results from quantum dynamics at avoided level crossings of the energy spectrum of single Ho^{3+} ions in the presence of hyperfine interactions. Enhanced quantum relaxation in constant transverse fields allows the study of the relative magnitude of tunnel splittings. At faster sweep rates, non-equilibrated spin-phonon and spin-spin transitions, mediated by weak dipolar interactions, lead to magnetization oscillations and additional steps.Comment: 5 pages, 5 eps figures, using RevTe

Navigating to new frontiers in behavioral neuroscience: traditional neuropsychological tests predict human performance on a rodent-inspired radial-arm maze

We constructed an 11-arm, walk-through, human radial-arm maze (HRAM) as a translational instrument to compare existing methodology in the areas of rodent and human learning and memory research. The HRAM, utilized here, serves as an intermediary test between the classic rat radial-arm maze (RAM) and standard human neuropsychological and cognitive tests. We show that the HRAM is a useful instrument to examine working memory ability, explore the relationships between rodent and human memory and cognition models, and evaluate factors that contribute to human navigational ability. One-hundred-and-fifty-seven participants were tested on the HRAM, and scores were compared to performance on a standard cognitive battery focused on episodic memory, working memory capacity, and visuospatial ability. We found that errors on the HRAM increased as working memory demand became elevated, similar to the pattern typically seen in rodents, and that for this task, performance appears similar to Miller's classic description of a processing-inclusive human working memory capacity of 7 ± 2 items. Regression analysis revealed that measures of working memory capacity and visuospatial ability accounted for a large proportion of variance in HRAM scores, while measures of episodic memory and general intelligence did not serve as significant predictors of HRAM performance. We present the HRAM as a novel instrument for measuring navigational behavior in humans, as is traditionally done in basic science studies evaluating rodent learning and memory, thus providing a useful tool to help connect and translate between human and rodent models of cognitive functioning

Code generation for sta architecture

Abstract. This paper presents a novel compiler backend which generates assembly code for Synchronous Transfer Architecture (STA). STA is a Very Long Instruction Word (VLIW) architecture and in addition it uses a non-orthogonal Instruction Set Architecture (ISA). Generating efficient code for this architecture needs highly optimizing techniques. The compiler backend presented in this paper is based on Integer Linear Programming (ILP). Experimental results show that the generated assembly code consumes much less execution time than the code generated by traditional ways, and the code generation can be accomplished in acceptable time.

Individual Experiences in Four Cancer Patients Following Psilocybin-Assisted Psychotherapy

A growing body of evidence shows that existential and spiritual well-being in cancer patients is associated with better medical outcomes, improved quality of life, and serves as a buffer against depression, hopelessness, and desire for hastened death. Historical and recent research suggests a role for psilocybin-assisted psychotherapy in treating cancer-related anxiety and depression. A double-blind controlled trial was performed, where 29 patients with cancer-related anxiety and depression were randomly assigned to treatment with single-dose psilocybin (0.3 mg/kg) or niacin in conjunction with psychotherapy. Previously published results of this trial demonstrated that, in conjunction with psychotherapy, moderate-dose psilocybin produced rapid, robust, and enduring anxiolytic, and anti-depressant effects. Here, we illustrate unique clinical courses described by four participants using quantitative measures of acute and persisting effects of psilocybin, anxiety, depression, quality of life, and spiritual well-being, as well as qualitative interviews, written narratives, and clinician notes. Although the content of each psilocybin-assisted experience was unique to each participant, several thematic similarities and differences across the various sessions stood out. These four participants’ personal narratives extended beyond the cancer diagnosis itself, frequently revolving around themes of self-compassion and love, acceptance of death, and memories of past trauma, though the specific details or narrative content differ substantially. The results presented here demonstrate the personalized nature of the subjective experiences elicited through treatment with psilocybin, particularly with respect to the spiritual and/or psychological needs of each patient

The PKC-β selective inhibitor, Enzastaurin, impairs memory in middle-aged rats

Enzastaurin is a Protein Kinase C-beta selective inhibitor that was developed to treat cancers. Protein Kinase C-beta is an important enzyme for a variety of neuronal functions; in particular, previous rodent studies have reported deficits in spatial and fear-conditioned learning and memory with lower levels of Protein Kinase C-beta. Due to Enzastaurin's mechanism of action, the present study investigated the consequences of Enzastaurin exposure on learning and memory in 12-month-old Fischer-344 male rats. Rats were treated daily with subcutaneous injections of either vehicle or Enzastaurin, and behaviorally tested using the spatial reference memory Morris Water Maze. Rats treated with Enzastaurin exhibited decreased overnight retention and poorer performance on the latter testing day, indicating a mild, but significant, memory impairment. There were no differences during the probe trial indicating that all animals were able to spatially localize the platform to the proper quadrant by the end of testing. RNA isolated from the hippocampus was analyzed using Next Generation Sequencing (lllumina). No statistically significant transcriptional differences were noted. Our findings suggest that acute Enzastaurin treatment can impair hippocampal-based learning and memory performance, with no effects on transcription in the hippocampus. We propose that care should be taken in future clinical trials that utilize Protein Kinase C-SS inhibitors, to monitor for possible cognitive effects, future research should examine if these effects are fully reversible.NIH-NINDS [R01-NS059873]; State of Arizona DHSOpen access journal.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Substrate binding in quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa studied by electron-nuclear double resonance

Binding of methanol to the quinoprotein ethanol dehydrogenase from Pseudomonas aeruginosa has been studied by pulsed electron-nuclear double resonance at 9 GHz. Shifts in the hyperfine couplings of the pyrroloquinoline quinone radical provide direct evidence for a change in the environment of the cofactor when substrate is present. By performing experiments with deuteriated methanol, we confirmed that methanol was the cause of the effect. Density functional theory calculations show that these shifts can be understood if a water molecule, which is often found in x-ray structures of the active site of quinoprotein alcohol dehydrogenases, is displaced by the substrate. The difference between the binding of water and methanol is that the water molecule forms a hydrogen bond to O5 of pyrroloquinoline quinone, which the methanol, by virtue of its methyl group, does not. The results support the proposal that aspartate rather than glutamate is the catalytically active base for a hydride transfer mechanism in quinoprotein alcohol dehydrogenases