Off-equilibrium scaling driven by time-dependent external fields in O(N) vector-models.

We investigate the off-equilibrium dynamics of spin systems with O(N) symmetry arising by the presence of slowly varying time-dependent external fields. We show the general theory and then focus on two different cases: a time-dependent magnetic field h(t,ts) ≈ t/ts, ts is a time scale, at the critical temperature and the temperature deviations T (t, ts )/Tc − 1 ≈ −t/ts in the absence of magnetic fields. We demonstrate the off-equilibrium scaling behaviours and formally compute the correlation functions in the limit of large N. We study the first deviations from the equilibrium in the correlation functions and prove that the matching occurs exponentially fast. We also consider analogous phenomena at the first-order transition which occurs in the ordered phase T < Tc along the line of zero magnetic field

Exact solution of time-dependent Lindblad equations with closed algebras

Time-dependent Lindblad master equations have important applications in areas ranging from quantum thermodynamics to dissipative quantum computing. In this paper we outline a general method for writing down exact solutions of time-dependent Lindblad equations whose superoperators form closed algebras. We focus on the particular case of a single qubit and study the exact solution generated by both coherent and incoherent mechanisms. We also show that if the time-dependence is periodic, the problem may be recast in terms of Floquet theory. As an application, we give an exact solution for a two-levels quantum heat engine operating in a finite-time.Comment: 15 pages, 12 figure

The development of strategies for interdisciplinary collaboration from within the visual arts.

The current cultural climate is stimulating an increasing interest in, and need for, collaboration throughout many fields of practice. Collaborative methods of art production are evident across a range of contemporary visual art practices and opportunities for interdisciplinary collaboration are becoming more available for artists, particularly those working beyond the gallery context. However, there is currently a lack of literature critically addressing collaborative processes in relation to visual arts practice. This research investigates strategies for interdisciplinary collaboration, which require different approaches than traditional, individual models of art practice. A visual artist (the researcher) adopts a practice-led, naturalistic methodology to investigate qualities and characteristics of the collaborative process and to develop and evaluate strategies for engaging successful interdisciplinary collaborations with practitioners from a variety of fields. A contextual review undertakes a broad review of literature and examples of practice addressing collaboration from the visual arts and other fields (including organisational and management theory). Key issues and approaches to collaboration are addressed in relation to instances of collaboration evident in the visual arts (collaboration between artists, collaboration in contemporary Public Art practices and interdisciplinary collaboration), and two main approaches to collaboration are identified: as a tacit method of practice and as an explicit methodology of practice. Three strands of inquiry are undertaken: collaboration in practice, collaboration in education, and case examples of collaboration. The researcher develops and evaluates strategies for engaging interdisciplinary collaboration with different collaborators in five exploratory research projects. Two projects are developed in an educational context to evaluate undergraduate Fine Art students experiences of collaboration. Three interviews with different visual art practitioners are undertaken to address their experiences of collaboration in professional arts contexts. A qualitative definition of collaboration, and a description of the main characteristics and key qualities of a collaborative process are obtained through a systematic, cross-comparative analysis of the research data (detailed project reports, pre-interview questionnaire forms and interview transcripts). These outcomes inform the development of a critical framework, which presents interpretative and evaluative criteria for identifying, describing and evaluating four distinct models of collaboration. The critical framework is primarily intended for use by visual artists as a tool for developing and evaluating their individual experiences of collaborative practice. The research contributes a new critical understanding of the more complex model of interdisciplinary collaboration and addresses the implications of approaching interdisciplinary collaboration as a viable methodology of practice for visual artists, in relation to both professional and educational visual art contexts

A COMPARISON OF MISSISSIPPIAN PERIOD SUBADULTS FROM THE MIDDLE CUMBERLAND AND EASTERN REGIONS OF TENNESSEE TO ASSESS HEALTH AND PAST POPULATION INTERACTIONS

Human subadult skeletal remains can provide a unique perspective into biosocial aspects of past populations. However, for a variety of reasons, they are often overlooked in the skeletal record. This is especially true for the Mississippian period (ca. 1000 years before present to ca. 400 years before present) populations that inhabited the Middle Cumberland region (MCR) and Eastern Tennessee Region (ETR). Most of the previous studies of these areas focused on adult skeletal remains, leaving out a large and extremely important population segment. To further expand current knowledge on the prehistory of the MCR and ETR, skeletal indicators of disease, growth, body proportions, and metabolic stress were investigated among the subadult remains from four archaeological sites. Crucial to overcoming limitations associated with the osteological paradox, the biological results were placed into an archaeological context based on prior studies as well as paleoclimatological data. Results demonstrate a high degree of homogeneity both within and between regions for most skeletal indicators investigated. Within the ETR, there is no evidence for biological differences between the Early Dallas, Late Dallas, and Mouse Creek cultural phases; this finding is consistent with previous studies of the adult skeletons. Despite the presumed signs of increased conflict at the Dallas site, rates and types of skeletal pathology and growth disruptions are comparable to other sites in the region. These findings suggest that there was no large-scale incursion of an outside population into the ETR during the Late Mississippian Period, or if one occurred, it is biologically invisible. Cultural differences between the ETR and MCR have been clearly demonstrated in previous studies. Although the skeletal data for the two regions are similar in many respects, there are several noteworthy differences. Namely, the subadults from the ETR display a higher frequency of pathology than those from MCR, while stature is significantly lower in younger subadults from the MCR. These results, combined with climatic and archaeobotanical data, suggests that the MCR subadults were under increased stress, especially during their earlier years. This may have been associated with increased interpersonal violence and dependence on few food sources occurring with greater scarcity

Out-of-equilibrium scaling behavior arising during round-trip protocols across a quantum first-order transition

We investigate the nonequilibrium dynamics of quantum spin chains during a round-trip protocol that slowly drives the system across a quantum first-order transition. Out-of-equilibrium scaling behaviors \`a la Kibble-Zurek for the single-passage protocol across the first-order transition have been previously determined. Here, we show that such scaling relations persist when the driving protocol is inverted and the transition is approached again by a far-from-equilibrium state. This results in a quasi-universality of the scaling functions, which keep some dependence on the details of the protocol at the inversion time. We explicitly determine such quasi-universal scaling functions by employing an effective two-level description of the many-body system near the transition. We discuss the validity of this approximation and how this relates to the observed scaling regime. Although our results apply to generic systems, we focus on the prototypical example of a $1D$ transverse field Ising model in the ferromagnetic regime, which we drive across the first-order transitions through a time-dependent longitudinal field.Comment: 13 pages, 18 figures; v2: minor changes; fixed some typo

Entanglement dynamics of a hard-core quantum gas during a Joule expansion

We study the entanglement dynamics of a one-dimensional hard-core quantum gas initially confined in a box of size $L$ with saturated density $\rho=1$. The gas is suddenly released into a region of size $2L$ by moving one of the box edges. We show that the analytic prediction for the entanglement entropy obtained from quantum fluctuating hydrodynamics holds quantitatively true even after several reflections of the gas against the box edges. We further investigate the long time limit $t/L\gg 1$ where a Floquet picture of the non-equilibrium dynamics emerges and hydrodynamics eventually breaks down.Comment: 24 pages, 15 figure

Development and Validation of a Box and Flux Model to Describe Major, Trace and Potentially Toxic Elements ({PTEs}) in Scottish Soils

The box and flux model is a mathematical tool used to describe and forecast the major and trace elements perturbations of the Earth biogeochemical cycles. This mathematical tool describes the biogeochemical cycles, using kinetics of first, second and even third order. The theory and history of the box and flux modeling are shortly revised and discussed within the framework of Jim Lovelok’s Gaia theory. The objectives of the investigation were to evaluate the natural versus anthropic load of Potentially Toxic Elements (PTEs) of the Scottish soils, investigate the soil components adsorbing and retaining the PTEs in non-mobile species, evaluate the aging factor of the anthropic PTEs and develop a model which describes the leaching of PTEs in layered soils. In the Scottish land, the soil-to-rock enrichment factorinversely correlates with the boiling point of the PTEs. The same is observed in NW Italy and USA soils, suggesting the common source of the PTEs. The residence time in soils of the measured PTEs linearly correlates with the Soil Organic Matter (SOM). The element property which mostly explains the adsorption capacity for PTEs’ is the ionic potential (IP). The downward migration rates of the PTEs inversely correlate with SOM, and in Scottish soil, they range from 0.5 to 2.0 cm·year−1. Organic Bentoniteis the most important soil phase adsorbing cation bivalent PTEs. The self-remediation time of the polluted soil examined ranged from 50 to 100 years. The aging factor, the adsorption of PTEs’ into non-mobile species, and occlusion into the soil mineral lattice was not effective. The box and flux model developed, tested and validatedhere does not describe the leaching of PTEs following the typical Gaussian shape distribution of the physical diffusion models. Indeed, the mathematical model proposed is sensitive to the inhomogeneity of the layered soils