Quantum Monte Carlo diagonalization for many-fermion systems

In this study we present an optimization method based on the quantum Monte Carlo diagonalization for many-fermion systems. Using the Hubbard-Stratonovich transformation, employed to decompose the interactions in terms of auxiliary fields, we expand the true ground-state wave function. The ground-state wave function is written as a linear combination of the basis wave functions. The Hamiltonian is diagonalized to obtain the lowest energy state, using the variational principle within the selected subspace of the basis functions. This method is free from the difficulty known as the negative sign problem. We can optimize a wave function using two procedures. The first procedure is to increase the number of basis functions. The second improves each basis function through the operators, $e^{-\Delta\tau H}$, using the Hubbard-Stratonovich decomposition. We present an algorithm for the Quantum Monte Carlo diagonalization method using a genetic algorithm and the renormalization method. We compute the ground-state energy and correlation functions of small clusters to compare with available data

Asymptotic Behaviour of Inhomogeneous String Cosmologies

The asymptotic behaviour at late times of inhomogeneous axion-dilaton cosmologies is investigated. The space-times considered here admit two abelian space-like Killing vectors. These space-times evolve towards an anisotropic universe containing gravitational radiation. Furthermore, a peeling-off behaviour of the Weyl tensor and the antisymmetric tensor field strength is found. The relation to the pre-big-bang scenario is briefly discussed.Comment: 15 pages, Late

Personality assessment in the Great Apes: Comparing ecologically valid behavior measures, behavior ratings, and adjective ratings

Three methods of personality assessment (behavior measures, behavior ratings, adjective ratings) were compared in 20 zoo-housed Great Apes: bonobos (Pan paniscus), chimpanzees (Pan troglodytes verus), gorillas (Gorilla gorilla gorilla), and orangutans (Pongo pygmaeus abelii). To test a new bottom-up approach, the studied trait constructs were systematically generated from the species’ behavioral repertoires. The assessments were reliable, temporally stable, and showed substantial cross-method coherence. In most traits, behavior ratings mediated the relations between adjective ratings and behavior measures. Results suggest that high predictability of manifest behavior is best achieved by behavior ratings, not by adjectives. Empirical evidence for trait constructs beyond current personality models points to the necessity of broad and systematic approaches for valid inferences on a species’ personality structure

Identification of factors required for meristem function in Arabidopsis using a novel next generation sequencing fast forward genetics approach

<p>Abstract</p> <p>Background</p> <p>Phenotype-driven forward genetic experiments are powerful approaches for linking phenotypes to genomic elements but they still involve a laborious positional cloning process. Although sequencing of complete genomes now becomes available, discriminating causal mutations from the enormous amounts of background variation remains a major challenge.</p> <p>Method</p> <p>To improve this, we developed a universal two-step approach, named 'fast forward genetics', which combines traditional bulk segregant techniques with targeted genomic enrichment and next-generation sequencing technology</p> <p>Results</p> <p>As a proof of principle we successfully applied this approach to two Arabidopsis mutants and identified a novel factor required for stem cell activity.</p> <p>Conclusion</p> <p>We demonstrated that the 'fast forward genetics' procedure efficiently identifies a small number of testable candidate mutations. As the approach is independent of genome size, it can be applied to any model system of interest. Furthermore, we show that experiments can be multiplexed and easily scaled for the identification of multiple individual mutants in a single sequencing run.</p

Developing the Weaving Healthy Families Program to Promote Wellness and Prevent Substance Abuse and Violence: Approach, Adaptation, and Implementation

Family prevention programs that enhance mental health, wellness, and resilience—while simultaneously addressing violence and alcohol and other drug (AOD) abuse—among Indigenous families are scarce. This gap in culturally grounded and community-based programs creates a critical need to develop and evaluate the efficacy of such prevention programs. This article fills this gap, with the purpose of describing the structure and content of the Weaving Healthy Families (WHF) program, a culturally grounded and community-based program aimed at preventing violence and AOD use while promoting mental health, resilience, and wellness in Indigenous families. The focus then turns to how to approach this process of developing and implementing the program in a culturally grounded and community-based way

Parkinson Disease Protein DJ-1 Binds Metals and Protects against Metal-induced Cytotoxicity

The progressive loss of motor control due to reduction of dopamine-producing neurons in the substantia nigra pars compacta and decreased striatal dopamine levels are the classically described features of Parkinson disease (PD). Neuronal damage also progresses to other regions of the brain, and additional non-motor dysfunctions are common. Accumulation of environmental toxins, such as pesticides and metals, are suggested risk factors for the development of typical late onset PD, although genetic factors seem to be substantial in early onset cases. Mutations of DJ-1 are known to cause a form of recessive early onset Parkinson disease, highlighting an important functional role for DJ-1 in early disease prevention. This study identifies human DJ-1 as a metal-binding protein able to evidently bind copper as well as toxic mercury ions in vitro. The study further characterizes the cytoprotective function of DJ-1 and PD-mutated variants of DJ-1 with respect to induced metal cytotoxicity. The results show that expression of DJ-1 enhances the cells' protective mechanisms against induced metal toxicity and that this protection is lost for DJ-1 PD mutations A104T and D149A. The study also shows that oxidation site-mutated DJ-1 C106A retains its ability to protect cells. We also show that concomitant addition of dopamine exposure sensitizes cells to metal-induced cytotoxicity. We also confirm that redox-active dopamine adducts enhance metal-catalyzed oxidation of intracellular proteins in vivo by use of live cell imaging of redox-sensitive S3roGFP. The study indicates that even a small genetic alteration can sensitize cells to metal-induced cell death, a finding that may revive the interest in exogenous factors in the etiology of PD