Dimensional Reduction, Hard Thermal Loops and the Renormalization Group

We study the realization of dimensional reduction and the validity of the hard thermal loop expansion for lambda phi^4 theory at finite temperature, using an environmentally friendly finite-temperature renormalization group with a fiducial temperature as flow parameter. The one-loop renormalization group allows for a consistent description of the system at low and high temperatures, and in particular of the phase transition. The main results are that dimensional reduction applies, apart from a range of temperatures around the phase transition, at high temperatures (compared to the zero temperature mass) only for sufficiently small coupling constants, while the HTL expansion is valid below (and rather far from) the phase transition, and, again, at high temperatures only in the case of sufficiently small coupling constants. We emphasize that close to the critical temperature, physics is completely dominated by thermal fluctuations that are not resummed in the hard thermal loop approach and where universal quantities are independent of the parameters of the fundamental four-dimensional theory.Comment: 20 pages, 13 eps figures, uses epsfig and pstrick

Entanglement in a molecular three-qubit system

We study the entanglement properties of a molecular three-qubit system described by the Heisenberg spin Hamiltonian with anisotropic exchange interactions and including an external magnetic field. The system exhibits first order quantum phase transitions by tuning two parameters, $x$ and $y$, of the Hamiltonian to specific values. The three-qubit chain is open ended so that there are two types of pairwise entanglement : nearest-neighbour (n.n.) and next-nearest-neighbour (n.n.n.). We calculate the ground and thermal state concurrences, quantifying pairwise entanglement, as a function of the parameters $x$, $y$ and the temperature $T$. The entanglement threshold and gap temperatures are also determined as a function of the anisotropy parameter $x$. The results obtained are of relevance in understanding the entanglement features of the recently engineered molecular $Cr_{7}Ni$-$Cu^{2+}$-$Cr_{7}Ni$ complex which serves as a three-qubit system at sufficiently low temperatures.Comment: 9 pages, 13 figures, revtex

Plant Oils and Products of Their Hydrolysis as Substrates for Polyhydroxyalkanoate Synthesis

Plant oils could provide a sustainable source of carbon for polyhydroxyalkanoate production as they are both renewable and inexpensive. No study to our knowledge has undertaken a comparative study of the use of major European and global commodity plants oils and products of their hydrolysis as substrates for medium chain length polyhydroxyalkanoate (mcl-PHA) production. There have been several studies which have investigated the use of plant oils and their hydrolysis products for short chain length PHA (scl-PHA) production, therefore, in this study, we have focused specifically on mcl-PHA-producing organisms. A comparison between direct growth on oils and the products of their hydrolysis is described here for several mcl-PHA-producing Pseudomonas strains. Pseudomonas putida KT2440, CA-3, GO16, Pseudomonas chlororaphis 555 were screened for their ability to utilize a range of common plant oils (olive, sunflower, rapeseed, and palm) and their hydrolysis products as sole sources of carbon and energy for growth and PHA accumulation. When the oils were supplied in shaken flask experiments, P. putida CA-3 and P. putida KT2440 showed little or no growth, while P. putida GO16 reached a cell dry weight of between 0.33 and 0.56 g L–1, and accumulated mcl-PHA to between 12 and 25 % of CDW, P. chlororaphis 555 reached a cell dry weight of between 0.67 and 0.86 g L–1, and accumulated mcl-PHA to between 27 and 34 % CDW in 48 h. In contrast, when the hydrolyzed fatty acid mixtures were supplied, all 4 strains tested grew and accumulated mcl-PHA. P. putida CA-3 and GO16 achieved the highest biomass (1.02 – 1.06 g L–1) with the majority of the hydrolyzed plant oil fatty acids, however P. chlororaphis 555 accumulated similar levels of PHA as these two strains. Despite being the strain of choice for mcl-PHA accumulation, for the majority of studies, P. putida KT2440 achieved less biomass and accumulated less PHA than other strains tested with the majority of oil-derived fatty acids. It is important to note that both biomass and PHA levels varied significantly across strain and hydrolyzed oil type. Due to the fact that P. chlororaphis 555 was able to grow and accumulate PHA from both plant oils and hydrolyzed oil fatty acids, it was selected for bioreactor trials to try to achieve high cell density and high PHA productivity using rapeseed oil and hydrolyzed rapeseed oil fatty acids. Rapeseed oil (RO) and its hydrolysis product (HROFA) were chosen for these experiments because P. chlororaphis 555 accumulated approximately 30 % mcl-PHA from both substrates, and as this oil can be produced globally, it would offer less barriers to scale-up than Palm oil. The mcl-PHA volumetric productivity with RO as the substrate was 0.53 g L–1 h–1 after 25 h with a yield of 0.22 g PHA g–1 oil, while the volumetric productivity with HROFA as the substrate was 0.54 g L–1 h–1 after 25 h with again a lower yield of 0.15 g PHA g–1 HROFA. Thus, under the fermentation conditions tested, HROFA was an inferior substrate for PHA production when compared to RO

Parallel transport in an entangled ring

This paper defines a notion of parallel transport in a lattice of quantum particles, such that the transformation associated with each link of the lattice is determined by the quantum state of the two particles joined by that link. We focus particularly on a one-dimensional lattice--a ring--of entangled rebits, which are binary quantum objects confined to a real state space. We consider states of the ring that maximize the correlation between nearest neighbors, and show that some correlation must be sacrificed in order to have non-trivial parallel transport around the ring. An analogy is made with lattice gauge theory, in which non-trivial parallel transport around closed loops is associated with a reduction in the probability of the field configuration. We discuss the possibility of extending our result to qubits and to higher dimensional lattices.Comment: 31 pages, no figures; v2 includes a new example of a qubit rin

Operationalization, implications and correlates of the cultural deviance criterion for ICD-11 and DSM-5 prolonged grief disorder

Prolonged Grief Disorder (PGD) is included in ICD-11 and DSM-5-TR and includes a requirement of cultural deviance. This study examined endorsement rates and factors associated with endorsement of this criterion among Danish bereaved spouses (n = 425) and their adult children (n = 159) four years post-loss. In total, 7.5% (n = 44) participants endorsed this criterion. Both including and excluding the criterion, the prevalence rates for probable DSM-5-TR PGD were 1.4% (n = 8) and 1.7% (n = 10), respectively and for probable ICD-11 PGD were 1.4% (n = 8) and 2.2% (n = 13), respectively. Age and gender of the deceased, age of the bereaved, greater grief severity, and comorbid psychopathology were positively associated with endorsement of the criterion. Findings demonstrate low endorsement of the cultural deviation criterion, that its inclusion excludes several potential PGD cases, and unanticipated associations with several factors raise questions about the criterion’s validity

In vivo characterization of key iridoid biosynthesis pathway genes in catnip (Nepeta cataria)

MAIN CONCLUSION: Using virus-induced gene silencing, we demonstrated that the enzymes GES, ISY, and MLPL are responsible for nepetalactone biosynthesis in Nepeta cataria. ABSTRACT: Nepetalactone is the main iridoid that is found in the Nepeta genus and is well-known for its psychoactive effect on house cats. Moreover, there is a burgeoning interest into the effect of nepetalactone on insects. Although the enzymes for nepetalactone biosynthesis have been biochemically assayed in vitro, validation of the role that these enzymes have in planta has not been demonstrated. Virus-induced gene silencing (VIGS) is a silencing method that relies on transient transformation and is an approach that has been particularly successful when applied to a variety of non-model plants. Here, we use a recently designed visual-marker dependent VIGS system to demonstrate that the nepetalactone biosynthetic enzymes GES, ISY, and MLPL impact nepetalactone biosynthesis in Nepeta cataria. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00425-022-04012-z

Atomistic modeling of amorphous silicon carbide: An approximate first-principles study in constrained solution space

Localized basis ab initio molecular dynamics simulation within the density functional framework has been used to generate realistic configurations of amorphous silicon carbide (a-SiC). Our approach consists of constructing a set of smart initial configurations that conform essential geometrical and structural aspects of the materials obtained from experimental data, which is subsequently driven via first-principles force-field to obtain the best solution in a reduced solution space. A combination of a priori information (primarily structural and topological) along with the ab-initio optimization of the total energy makes it possible to model large system size (1000 atoms) without compromising the quantum mechanical accuracy of the force-field to describe the complex bonding chemistry of Si and C. The structural, electronic and the vibrational properties of the models have been studied and compared to existing theoretical models and available data from experiments. We demonstrate that the approach is capable of producing large, realistic configurations of a-SiC from first-principles simulation that display excellent structural and electronic properties of a-SiC. Our study reveals the presence of predominant short-range order in the material originating from heteronuclear Si-C bonds with coordination defect concentration as small as 5% and the chemical disorder parameter of about 8%.Comment: 16 pages, 7 figure