Differential scanning calorimetry (DSC) has been employed to investigate the glass transition activation energy E g, thermal stability and glass-forming ability (GFA) of Se90In10− x Sb x (x = 0, 2, 4, 6, 8, 10) chalcogenide glasses. DSC runs were performed at six different heating rates. Well-defined endothermic and exothermic peaks were obtained at glass transition and crystallization temperature. The dependence of glass transition temperature T g on heating rate (α), as well as composition of (...) Sb, has been studied. From the dependence of glass transition temperature on heating rate, the E g has been calculated on the basis of the Kissinger [Anal. Chem. 29 (1957) p.1702] and Moynihan [J. Phys. Chem. 78 (1974) p.267] models. Thermal stability has been monitored through the calculation of temperature differences T c–T g, the stability parameter S, and the enthalpy released during crystallization H c. The GFA has been investigated on the basis of the Hruby parameter H r, which is strong indicator of GFA. Results for GFA are in good agreement with fragility index F i calculations, indicating that Se90In6Sb4 is an excellent glass-former. (shrink)

Ni-44 at.% Al and Ni-50 at.% Al single crystals were tested in compression in the hard d 001 ¢ orientation. The dislocation processes and deformation behaviour were studied as a function of temperature, strain and strain rate. A slip transition in NiAl occurs from a d 111 ¢ slip to non- a d 111 ¢ slip at intermediate temperatures. In Ni-50 at.% Al single crystals, only a d 010 ¢ dislocations are observed above the slip transition (...) class='Hi'>temperature. In contrast, a d 101 ¢ {101} glide has been observed to control deformation beyond the slip transition temperature in Ni-44 at.% Al. a d 101 ¢ dislocations are observed primarily along both d 111 ¢ directions in the glide plane. High-resolution transmission electron microscopy observations show that the core of the a d 101 ¢ dislocations along these directions is decomposed into two a d 010 ¢ dislocations, separated by a distance of approximately 2 nm. The temperature window of stability for these a d 101 ¢ dislocations depends upon the strain rate. At a strain rate of 1.4 2 10 m 4 s m 1 , a d 101 ¢ dislocations are observed between 800 and 1000 K. Complete decomposition of a d 101 ¢ dislocations into a d 010 ¢ dislocations occurs beyond 1000 K, leading to a d 010 ¢ climb as the deformation mode at higher temperatures. At lower strain rates, decomposition of a d 101 ¢ dislocations has been observed to occur along the edge orientation at temperatures below 1000 K. Embedded-atom method calculations and experimental results indicate that a d 101 ¢ dislocations have a large Peierls stress at low temperatures. Based on the present microstructural observations and a survey of the literature with respect to vacancy content and diffusion in NiAl, a model is proposed for a d 101 ¢ {101} glide in Ni-44 at.% Al, and for the observed yield strength versus temperature behaviour of Ni-Al alloys at intermediate and high temperatures. (shrink)

The ternary xV2O5–(40 − x)Li2O–60B2O3 glass system, where x = 1, 2, 3, 4 and 6 mol%, was prepared by normal quenching. Ultrasonic velocities and attenuation were measured at room temperature using a pulse-echo technique. Various parameters, such as elastic moduli, micro-hardness, Poisson's ratio and Debye temperature, were determined from the measured densities and velocities. The composition dependence of these parameters, in addition to the glass-transition temperature, suggested that vanadium ions were incorporated into these glasses as (...) a network modifier, resulting in the reconversion of BO4 tetrahedra to BO3 triangles by the breaking of B–O–B linkages and the formation of nonbridging oxygens (NBOs). The outcome was a reduction in network connectivity and rigidity with increasing V2O5 content. The results are explained quantitatively in terms of fractal bond connectivity, average atomic volume, network dimensionality, packing density, number of network bonds per unit volume, cross-link density and atomic ring size. The Makishima and Mackenzie model appears to be valid for the studied glasses when the fate of BO4 tetrahedra and creation of NBOs are taken into account. (shrink)

It is often argued that the indispensability of continuum models comes from their empirical adequacy despite their decoupling from the microscopic details of the modelled physical system. There is thus a commonly held misconception that temperature varying across a region of space or time can always be accurately represented as a continuous function. We discuss three inter-related cases of temperature modelling — in phase transitions, thermal boundary resistance and slip flows — and show that the continuum view is (...) fallacious on the ground that the microscopic details of a physical system are not necessarily decoupled from continuum models. We show how temperature discontinuities are present in both data (experiments and simulations) and phenomena (theory and models) and how discontinuum models of temperature variation may have greater empirical adequacy and explanatory power. The conclusions of our paper are: a) continuum idealisations are not indispensable to modelling physical phenomena and both continuous and discontinuous representations of phenomena work depending on the context; b) temperature is not necessarily a continuously defined function in our best scientific representations of the world; and c) that its continuity, where applicable, is a contingent matter. We also raise a question as to whether discontinuous representations should be considered truly de-idealised descriptions of physical phenomena. (shrink)

In this work we review the formalism used in describing the thermodynamics of first-order phase transitions from the point of view of maximum entropy inference. We present the concepts of transition temperature, latent heat and entropy difference between phases as emergent from the more fundamental concept of internal energy, after a statistical inference analysis. We explicitly demonstrate this point of view by making inferences on a simple game, resulting in the same formalism as in thermodynamical phase transitions. We (...) show that analogous quantities will inevitably arise in any problem of inferring the result of a yes/no question, given two different states of knowledge and information in the form of expectation values. This exposition may help to clarify the role of these thermodynamical quantities in the context of different first-order phase transitions such as the case of magnetic Hamiltonians. (shrink)

Two prevailing paradigms explain the diversity of sex-determining modes in reptiles. Many researchers, particularly those who study reptiles, consider genetic and environmental sex-determining mechanisms to be fundamentally different, and that one can be demonstrated experimentally to the exclusion of the other. Other researchers, principally those who take a broader taxonomic perspective, argue that no clear boundaries exist between them. Indeed, we argue that genetic and environmental sex determination in reptiles should be seen as a continuum of states represented by species (...) whose sex is determined primarily by genotype, species where genetic and environmental mechanisms coexist and interact in lesser or greater measure to bring about sex phenotypes, and species where sex is determined primarily by environment. To do otherwise limits the scope of investigations into the transition between the two and reduces opportunities to use studies of reptiles to advance understanding of vertebrate sex determination generally. © 2004 Wiley Periodicals, Inc. (shrink)

White LEDs, which have been widely used in the urban street lighting, are increasingly applied to replace traditional HPS lamps with a lower CCT. Generally, studies on the CCT of street lighting focus on providing safe functional lighting for vehicle drivers. However, it is still unknown how the street light color can affect pedestrians’ perception and preferences with respect to lighting levels and ambient temperature.In this study, a wide range of CCTs was measured for urban street lighting in Beijing, (...) China, for example. And the transition from traditional HPS lamps to LEDs lacks a reference street lighting standard for CCT. The study aims to conduct a cross-sensory test to evaluate urban street lighting with multiple combinations of CCT values and illuminance levels according to pedestrians’ visual perception and psychological preferences.A total of 18 night street lighting scenes with six CCT values and three illuminance levels were first selected in Beijing city, and then HDR videos of these scenes were taken from the view of pedestrians to conduct psychological experiments in an indoor environment with three ambient temperatures. A total of 77 university students were invited to assess videos of the 18 lighting scenes in terms of seven factors, such as lighting brightness, color temperature sensation, light color preference, sense of safety, recognition, comfort, and overall preference. Several key findings were achieved as follows. The CCT of urban street lighting can have significant effects on the visual psychological perceptions of participants. There was a significant interaction between CCT, illuminance, and ambient temperature on the visual psychological performances of participants. The higher ambient temperature will deliver the higher level of overall preference for the street lighting with medium and high CCT, and the perception of warmer light color. There was a strong correlation found between participants’ light color preference, comfort, and overall preferences. (shrink)

It is well established that single crystals of B2-structured Fe-Al change from paramagnetic to ferromagnetic upon plastic deformation. This strain-induced ferromagnetism arises mostly from Fe atoms which have three or more like nearest neighbours in antiphase-boundary tubes. Such Fe atoms carry magnetic moments according to their local environment. In this study, the saturation magnetizations, M S , of cold-rolled Fe-34 at.% Al, Fe-40 at.% Al and Fe-43 at.% Al single crystals were measured in a vibrating-sample magnetometer from 77 K to (...) room temperature and transmission electron microscopy was used to confirm the presence of APB tubes. After magnetic measurements, rolled single crystals were heated in a differential scanning calorimeter at 20 K min m 1 to 973 K and the enthalpy associated with the removal of the APB tubes measured. From the enthalpy measurement, the APB tube density and the number of Fe NNs were estimated. Hence, the M S values at 0 K were calculated. These were in good agreement with the experimentally determined values. (shrink)

After World War II, quite a few mathematicians, including Mark Kac, John von Neumann, and Nobert Wiener, worked on the physical problem of phase transitions, i.e. changes in the state of matter caused by gradual changes of physical parameters such as the condensation of a gas to a liquid and the loss of magnetization of a ferromagnet above a certain temperature. The significance of these mathematicians was not so much that they brought mathematical rigor to the theoretical description of (...) the phenomena,1 but that they applied their mathematical skills and tools to solve concrete mathematical problems encountered in the microscopic modeling of phase transitions. The present paper deals... (shrink)

The first classification of general types of transition between phases of matter, introduced by Paul Ehrenfest in 1933, lies at a crossroads in the thermodynamical study of critical phenomena. It arose following the discovery in 1932 of a suprising new phase transition in liquid helium, the “lambda transition,” when W. H. Keesom and coworkers in Leiden, Holland observed a λhaped “jump” discontinuity in the curve giving the temperature dependence of the specific heat of helium at a (...) critical value. This apparent jump led Ehrenfest to introduce a classification of phase transitions on the basis of jumps in derivatives of the free energy function. This classification was immediately applied by A.J. Rutgers to the study of the transition from the normal to superconducting state in metals. Eduard Justi and Max von Laue soon questioned the possibility of its class of “second-order phase transitions” -- of which the “lambda transition was believed to be the arche type -- but C.J. Gorter and H.B.G. Casimir used an “order parameter to demonstrate their existence in superconductors. As a crossroads of study, the Ehrenfest classification was forced to undergo a slow, adaptive evolution during subsequent decades. During the 1940s the classification was increasingly used in discussions of liquid-gas, order-disorder, paramagnetic-ferromagnetic and normal-super-conducting phase transitions. Already in 1944 however, Lars Onsagers solution of the Ising model for two-dimensional magnets was seen to possess a derivative with a logarithmic divergence rather than a jump as the critical point was approached. In the 1950s, experiments further revealed the lambda transition in helium to exhibit similar behavior. Rather than being a prime example of an Ehrenfest phase transition, the lambda transition was seen to lie outside the Ehrenfest classification. The Ehrenfest scheme was then extended to include such singularities, most notably by A. Brain Pippard in 1957, with widespread acceptance. During the 1960s these logarithmic infinities were the focus of the investigation of “scaling” by Leo Kadanoff, B. Widom and others. By the 1970s, a radically simplified binary classification of phase transitions into “first-order” and “continuous” transitions was increasingly adopted. (shrink)

Window opening behavior in residential buildings has important theoretical significance and practical value for improving energy conservation, indoor thermal comfort, and indoor air quality. Climate and cultural differences may lead to different window opening behavior by residents. Currently, research on residential window opening behavior in northwest China has focused on indoor air quality, and few probabilistic models of residential window behaviors have been established. Therefore, in this study, we focused on an analysis of factors influencing window opening behavior and the (...) establishment of a predictive model for window opening behavior. Four typical residential buildings in different locations and building types in Xi’an were selected. The indoor and outdoor environments and window opening states were measured. Subsequently, a multivariate analysis of variance was used to determine the factors that had a significant effect on window opening behavior. Single- and multiparameter logistic regression models for window opening behavior were established. Of all the measured factors, we found that indoor temperature and CO2 concentration, outdoor temperature, and relative humidity had significant effects on window opening behavior, and indoor relative humidity and noise did not. Meanwhile, the temperature was positively correlated with the window opening probability, whereas indoor CO2 concentration and outdoor relative humidity were negatively correlated. The prediction accuracy of the multiparameter model was promising, at almost 75%, and the model can provide theoretical support for modelling residential buildings in Xi’an. (shrink)

We report specific heat and μSR measurements on Th and/or B substituted UBe13. The specific heat data show that either Th or B substitution reduces the Kondo temperature TK and increases the entropy at the superconducting transition by almost 20%, indicating an enhanced density of states. However, whereas μSR shows clear evidence for magnetic correlations for Th substitutions, no magnetism is observed for B substitutions. The enhanced specific heat jump in the B-substituted material is associated with a change (...) in the superconducting properties as TK is reduced. (shrink)

Climate change is expected to lead to rising sea levels, higher frequency of natural hazards, extended phases of drought, and many other negative impacts. To minimize these threats, the 21st Conference of the Parties (COP 21) in Paris agreed that the global mean temperature must be kept “well below 2 °C above pre-industrial levels” (United Nations 2015). For this target to be feasible, most climate models assume not only heavy cuts in emissions but also negative emissions via the large-scale (...) capture and storage of carbon dioxide (K. Anderson and Peters 2016). This chapter investigates the considerations of ethics and justice that are relevant to the fair governance of the carbon capture and storage technologies required to produce negative emissions.1 I argue that the governance of these negative emission technologies (NETs) demands the fair distribution of the additional burdens and risks associated with them and that their ethical evaluation requires the appropriate involvement of those most directly affected. The main argument justifying these claims relies on the infeasibility of achieving justice in the governance of NETs. However, the solutions recommended for dealing with this challenge also face some feasibility constraints. I demonstrate how challenges of feasibility shape the directions of moral thinking about this area of climate action. (shrink)

A superconducting transition temperature as high as 100 K was recently discovered in one monolayer FeSe grown on SrTiO3. The discovery ignited efforts to identify the mechanism for the markedly enhanced Tc from its bulk value of 8 K. There are two main views about the origin of the Tc enhancement: interfacial effects and/or excess electrons with strong electron correlation. Here, we report the observation of superconductivity below 20 K in surface electron-doped bulk FeSe. The doped surface layer (...) possesses all the key spectroscopic aspects of the monolayer FeSe on SrTiO3. Without interfacial effects, the surface layer state has a moderate Tc of 20 K with a smaller gap opening of 4.2 meV. Our results show that excess electrons with strong correlation cannot induce the maximum Tc, which in turn reveals the need for interfacial effects to achieve the highest Tc in one monolayer FeSe on SrTiO3. (shrink)

The effect of germanium addition on the physical properties, i.e. density, molar volume, compactness, number of lone-pair electrons, average coordination number, heat of atomization, mean bond energy, cohesive energy and glass-transition temperature, of (Se80Te20)100− x Ge x (x = 0, 2, 4, 6) bulk glassy alloys was investigated. The density of the glassy alloys is found to decrease with increasing Ge content. The molar volume and compactness of the structure of the glass were determined from the measured density. (...) The mean bond energy is proportional to the glass-transition temperature. The cohesive energy of the samples has been calculated using a chemical bond approach and is correlated with an increase in the optical energy gap with increase in the Ge content. The heat of atomization was also calculated and correlated with the optical energy gap. The glass-transition temperature has been estimated using different methods and is found to increase with an increase of Ge content. (shrink)

The evolution of microstructure upon partial crystallization and its influence on the mechanical properties such as hardness, elastic modulus and viscosity in a La 55 Al 25 Cu 10 Ni 5 Co 5 bulk metallic glass alloy are studied. Specimens with various volume fractions of crystalline phases were obtained by annealing the as-cast amorphous alloy above its glass transition temperature and were characterized by transmission electron microscopy. Microscopic examination of the heat-treated samples shows short-range-ordered domains prior to nanocrystallization (...) within the amorphous matrix, followed by the growth and impingement of the crystallites. Whereas the hardness of the annealed samples increases linearly with increasing crystallinity, the elastic modulus and the viscosity both increase abruptly when the crystalline volume fraction is about 40 vol.%, with a only minor variation on either side of this range. The sudden rises in the modulus and viscosity are similar to those in the literature data on the fracture strength of partially crystallized bulk amorphous alloys that shows a steep drop in strength at 30-50 vol.% crystallinity. On the basis of the microscopic observations, it is suggested that the interaction and formation of rigid networks of crystalline phases upon the attainment of a critical second-phase volume fraction may be the possible reason for the sudden change in mechanical properties. Percolation theory is utilized in further substantiating this hypothesis. (shrink)

The Hartree–Fock–Popov theory of interacting Bose particles is generalized to the Cooper-pair system with a screened Coulomb repulsive interaction in high-temperature superconductors. At zero temperature, it is found that the condensate density \\) of Cooper pairs is of the order \\simeq 10^{18}\) cm\, consistently with the fact that a small fraction of the total p holes participate in pairing. We find that the phonon velocity c at zero temperature is of the order \\simeq 10\) km s\. The (...) computation shows that the transition temperature \ is a dome-shaped function of the p hole concentration \, which is consistent with experiments. At finite temperature, we find that the condensate fraction \/n\) decreases continuously from \/n\) to zero as the temperature increases from zero to the transition temperature \. For higher temperatures, we find that the repulsive interaction between Cooper pairs drives more Cooper pairs into the condensate. The computation reveals that the phonon velocity c decreases continuously from c to zero as the temperature increases from zero to the transition temperature \. The Cooper-pair system undergoes a first-order phase transition from the normal state to the BEC state. (shrink)

Modern microscopic theory is employed to construct a powerful analytical algorithm that permits a clear description of characteristic features of strongly correlated quantum fluids in thermodynamic equilibrium. Using recently developed formal results we uncover an intricate relationship between strongly correlated systems and free quantum gases of appropriately defined constituents. The latter entities are precisely defined renormalized bosons or fermions. They carry all the information contained in the statistical correlations of the strongly interacting many-particle system by virtue of their effective masses. (...) The mass of such a renormalized boson or fermion depends in a specific form on temperature, bulk particle number density of the many-body system, and eventually on momentum. Due to these properties the renormalized bosons and fermions determine in particular the location and nature of the transition to non-normal phases. (shrink)

This thesis addresses the surprising features of zero-temperature statics and dynamics of several spin glass models, including correlations between soft spins that arise spontaneously during avalanches, and the discovery of localized states that involve the presence of two-level systems. It also presents the only detailed historiographical research on the spin glass theory. Despite the extreme simplicity of their definition, spin glasses display a wide variety of non-trivial behaviors that are not yet fully understood. In this thesis the author sheds (...) light on some of these, focusing on both the search for phase transitions under perturbations of Hamiltonians and the zero-temperature properties and responses to external stimuli. After introducing spin glasses and useful concepts on phase transitions and numerics, the results of two massive Monte Carlo campaigns on three-dimensional systems are presented: The first of these examines the de Almeida-Thouless transition, and proposes a new finite-size scaling ansatz, which accelerates the convergence to the thermodynamic limit. The second reconstructs the phase diagram of the Heisenberg spin glass with random exchange anisotropy. (shrink)

The frequency and temperature dependences of the ac conductivity and dielectric constant of the V 2 O 5 -MnO-TeO 2 system, containing two transition-metal ions, have been measured. The dc conductivity † dc measured in the high-temperature range decreases with addition of the oxide MnO. This is considered to be due to the formation of bonds such as V--O--Mn and Mn--O--Mn in the glass. The conductivity arises mainly from polaron hopping between V 4+ and V 5+ ions. (...) It is found that a mechanism of adiabatic small-polaron hopping is the most appropriate conduction model for these glasses. This is in sharp contrast with the behaviour of the Mn-free V 2 O 5 -TeO 2 glass, in which non-adiabatic hopping takes place. High-temperature conductivity data satisfy Mott's small-polaron hopping model and also a model proposed by Schnakenberg in 1968. A power-law behaviour † ac = A y s , with s < 1) is well exhibited by the ac conductivity † ac data of these glasses. Analysis of dielectric data indicates a Debye-type relaxation behaviour with a distribution of relaxation times. The MnO-concentration-dependent † ac data follow an overlapping large-polaron tunnelling model over the entire range of temperatures studied. The estimated model parameters are reasonable and consistent with changes in composition. (shrink)

In this paper we argue that one-way quantum computation can be seen as a form of phase transition with the available information about the solution of the computation being the order parameter. We draw a number of striking analogies between standard thermodynamical quantities such as energy, temperature, work, and corresponding computational quantities such as the amount of entanglement, time, potential capacity for computation, respectively. Aside from being intuitively pleasing, this picture allows us to make novel conjectures, such as (...) an estimate of the necessary critical time to finish a computation and a proposal of suitable architectures for universal one-way computation in 1D. (shrink)

The environmental quality and subjective environmental evaluations in urban open spaces are essential. In this study, the effects of building, green, and water landscapes, which are typical visual landscapes, on the subjective environmental evaluations in different seasons were analyzed by conducting questionnaire surveys and field measurements in a severely cold city. It was found that the visual landscapes significantly affected subjective environmental evaluations in winter and summer, but there were no effects in the transitional season. In summer, compared with the (...) building and green landscape, the thermal sensation vote in the water landscape was the lowest at 0.4, and the differences were 0.3∼1.0. However, the thermal comfort vote in the water landscape was found to be 0.6 times higher. In winter, the thermal sensation and comfort votes in the water landscape were the lowest, the average evaluation under different UTCI was –2.2, and the results were similar for the overall comfort evaluation. In addition, the subjects believed that green and water landscapes improved thermal comfort and had more significant effects on improving the environmental temperature in the three seasons. Additionally, visual landscape evaluations significantly affect subjective environmental evaluations in summer than in the winter and transitional season; the higher the visual landscape evaluation, the better the thermal and overall comfort. (shrink)

My life as a quantum physicist / M. Nakahara -- A review on operator quantum error correction - Dedicated to Professor Mikio Nakahara on the occasion of his 60th birthday / C.-K. Li, Y.-T. Poon and N.-S. Sze -- Implementing measurement operators in linear optical and solid-state qubits / Y. Ota, S. Ashhab and F. Nori -- Fast and accurate simulation of quantum computing by multi-precision MPS: Recent development / A. Saitoh -- Entanglement properties of a quantum lattice-gas model on (...) square and triangular ladders / S. Tanaka, R. Tamura and H. Katsura -- On signal amplification from weak-value amplification / Y. Shikano -- Topological protection of quantum information / K. Fujii -- Quantum annealing with antiferromagnetic fluctuations for mean-field models / Y. Seki and H. Nishimori -- A method to change phase transition nature - Toward annealing methods / R. Tamura and S. Tanaka -- Computational analysis of the first stage of the photosynthetic system, the light-dependent reaction, by quantum chemical simulation method / M. Tada-Umezaki -- Two-qubit gate operation on selected nearest neighboring qubits in a neutral atom quantum computer / E. Hosseini Lapasar... [et al.] -- A simple operator quantum error correction scheme avoiding fully correlated errors / C. Bagnasco, Y. Kondo and M. Nakahara -- Black hole predictability, classical and quantum / A. Ishibashi -- Classical field simulation of finite-temperature Bose gases / T. Sato -- Atomic quantum simulations of lattice gauge theory: Effect of gauge symmetry breaking / K. Kasamatsu, I. Ichinose and T. Matsui -- Recursive construction of noiseless subsystem for qudits / U. Gungordu... [et al.] -- Composite quantum gates for precise quantum control / M. Bando... [et al.] -- New formulation of statistical mechanics using thermal pure quantum states / S. Sugiura and A. Shimizu -- Thermodynamics in unitary time evolution / T. N. Ikeda -- Second law of thermodynamics with QC-mutual information / T. Sagawa. (shrink)

Physical arguments stemming from the theory of black-hole thermodynamics are used to put constraints on the dynamics of closed-string tachyon condensation in Scherk–Schwarz compactifications. A geometrical interpretation of the tachyon condensation involves an effective capping of a noncontractible cycle, thus removing the very topology that supports the tachyons. A semiclassical regime is identified in which the matching between the tachyon condensation and the black-hole instability flow is possible. We formulate a generalized correspondence principle and illustrate it in several different circumstances: (...) an Euclidean interpretation of the transition from strings to black holes across the Hagedorn temperature and instabilities in the brane-antibrane system. (shrink)

Relativistic mean field theory with mesons σ, ω, π and ρ mediating interactions and nucleons as basic fermions has been very successful in describing nuclear matter and finite nuclei. However, in heavy-ion collisions, where the c. m. energy of two colliding nucleons will be in the hundreds of GeV region, nucleons are not expected to behave as point-like particles. Analyses of elastic pp and ¯pp scattering data in the relevant c. m. energy range show that the nucleon is a composite (...) object—a topological soliton or Skyrmion embedded in a condensed quark-antiquark ground state. Against this backdrop, we formulate an effective field theory model of nuclear matter based on the gauged linear σ-model where quarks are the basic fermions, but the mesons still mediate the interactions. The model describes the nucleon as a Skyrmion and produces a q¯q ground state analogous to a superconducting ground state. Quarks are quasi-particles in this ground state. When the temperature exceeds a critical value, the scalar field in the ground state vanishes, quarks become massless, and a chiral phase transition occurs leading to chiral symmetry restoration. We explore the possibility of a first order phase transition in this model by introducing suitable self-interactions of the scalar field. Internal structures of the Skyrmions are ignored, and they are treated as point-like fermions. (shrink)

The concept of contextual emergence has been proposed as a non-reductive, yet well- defined relation between different levels of description of physical and other systems. It is illustrated for the transition from statistical mechanics to thermodynamical properties such as temperature. Stability conditions are shown to be crucial for a rigorous implementation of contingent contexts that are required to understand temperature as an emergent property. Are such stability conditions meaningful for contextual emergence beyond physics as well? An affirmative (...) example from cognitive neuroscience addresses the relation between neurobiological and mental levels of description. For a particular class of partitions of the underlying neurobiological phase space, so-called generating partitions, the emergent mental states are stable under the dynamics. In this case, mental descriptions are (i) faithful representations of the neurodynamics and (ii) compatible with one another. (shrink)

In this manuscript we initiate a systematic examination of the physical basis for the time concept in cosmology. We discuss and defend the idea that the physical basis of the time concept is necessarily related to physical processes which could conceivably take place among the material constituents available in the universe. As a consequence we motivate the idea that one cannot, in a well-defined manner, speak about time ‘before’ such physical processes were possible, and in particular, the idea that one (...) cannot speak about a time scale ‘before’ scale-setting physical processes were possible. It is common practice to link the concept of cosmic time with a space-time metric set up to describe the universe at large scales, and then define a cosmic time t as what is measured by a comoving standard clock. We want to examine, however, the physical basis for setting up a comoving reference frame and, in particular, what could be meant by a standard clock. For this purpose we introduce the concept of a `core' of a clock and we ask if such a core can - in principle - be found in the available physics contemplated in the various `stages' of the early universe. We find that a first problem arises above the quark-gluon phase transition where there might be no bound systems left, and the concept of a physical length scale to a certain extent disappears. A more serious problem appears above the electroweak phase transition believed to occur at $\sim 10^{-11}$ seconds. At this point the property of mass disappears and it becomes difficult to identify a physical basis for concepts like length scale, energy scale and temperature - which are all intimately linked to the concept of time in modern cosmology. This situation suggests that the concept of a time scale in `very early' universe cosmology lacks a physical basis or, at least, that the time scale will have to be based on speculative new physics. (shrink)

This paper aims: (1) to show that Lawrence Sklar`s recent attempt to reduce thermodynamics(TD) to statistical mechanics(SM) is fallacious in several respects; and (2) to suggest a broader conclusion that a more useful way of understanding the relationship between TD and SM is as collaboration and competition among alternative methodologies rather than reduction of one theory to another. To argue for (1), I discuss two cases (the distinction of intensive/extensive variables in TD and the existence of phase transitions) where TD (...) is more accurate than statistical mechnaics and thus corrects SM. I also discuss the case of temperature in order to argue for both (1) and (2). (shrink)

The concept of contextual emergence is proposed as a non-reductive, yet welldefined relation between different levels of description of physical and other systems. It is illustrated for the transition from statistical mechanics to thermodynamical properties such as temperature. Stability conditions are crucial for a rigorous implementation of contingent contexts that are required to understand temperature as an emergent property. It is proposed that such stability conditions are meaningful for contextual emergence beyond physics as well.

The extent of our duties to mitigate climate change is commonly conceptualized in terms of temperature goals like the 1.5°C and the 2°C target and corresponding emissions budgets. While I do acknowledge the political advantages of any framework that is relatively easy to understand, I argue that this particular framework does not capture the true extent of our mitigation duties. Instead I argue for a more differentiated approach that is based on the well-known distinction between subsistence and luxury emissions. (...) At the heart of this approach lies the argument that we have no budget of substantial, net-positive luxury emissions left. In a world in which dangerous climate change has begun, we must expect all further substantial, net-positive luxury emissions to cause harm. Since they lack the kind of justification needed for them to be nevertheless permissible, I conclude that we must stop emitting them with immediate effect. I also briefly discuss the difficult case of subsistence emissions and offer some first thoughts on the morality of a third category of emissions, what I call ‘transition emissions’. (shrink)

I propose an experiment that may be performed, with present low temperature and cryogenic technology, to reveal Wheeler’s quantum foam. It involves coupling an optical photon’s momentum to the center of mass motion of a macroscopic transparent block with parameters such that the latter is displaced in space by approximately a Planck length. I argue that such displacement is sensitive to quantum foam and will react back on the photon’s probability of transiting the block. This might allow determination of (...) the precise scale at which quantum fluctuations of space–time become large, and so differentiate between the brane-world and the traditional scenarios of spacetime. (shrink)

The formulation of the second law of thermodynamics in the frame of general relativity is reconsidered in the case of an istotropic homogeneous universe. We show that there appears then a direct link between the cosmological state of the universe, as expressed in terms of conformal coordinates, and quantities such as energy density, pressure, and entropy associated with the description of nature. In the early universe there appears a kind of phase transition due to transfer of gravitational energy to (...) matter associated with the cosmological expansion if the universe starts with a non-Euclidian (space) state. As a result, we may envisage the possibility of a “cold big-bang model,” in which the universe would start at zero temperature and entropy. The temperature goes then through a maximum before entering the present area of cooling related to adiabatic expansion. (shrink)

The philosophy of Aristotle and its impact on the process of empirical scientific inquiry has been substantial. The influence of the clarity and orderliness of his thinking, when applied to the acquisition of knowledge in nursing, can not be overstated. Traditional empirical approaches have and will continue to have an important influence on the development of nursing knowledge through nursing research. However, as nursing is primarily a practice discipline, the transition from empirical and syllogistic reasoning is problematic. Other types (...) of inquiry are essential in the application of nursing knowledge obtained by empirical scientific approaches and to understand how that knowledge can best be used in the care of patients. This paper reviews the strengths and limitations of syllogistic reasoning by applying it to a recently published study on temperature measurement in nursing. It then discusses possible ways that the empirical knowledge gained from that study and confirmed in its reasoning by logical analysis could be used in the daily care of critically ill patients. It concludes by highlighting the utility of broader approaches to knowledge development, including interpretative approaches and contemporary empiricism, as a way to bridge the gap between factual empirical knowledge and the practical application of that knowledge in everyday clinical nursing practice. (shrink)