Phonon anharmonicity and negative thermal expansion in SnSe

The anharmonic phonon properties of SnSe in the Pnma phase were investigated with a combination of experiments and first-principles simulations. Using inelastic neutron scattering (INS) and nuclear resonant inelastic X-ray scattering (NRIXS), we have measured the phonon dispersions and density of states (DOS) and their temperature dependence, which revealed a strong, inhomogeneous shift and broadening of the spectrum on warming. First-principles simulations were performed to rationalize these measurements, and to explain the previously reported anisotropic thermal expansion, in particular the negative thermal expansion within the Sn-Se bilayers. Including the anisotropic strain dependence of the phonon free energy, in addition to the electronic ground state energy, is essential to reproduce the negative thermal expansion. From the phonon DOS obtained with INS and additional calorimetry measurements, we quantify the harmonic, dilational, and anharmonic components of the phonon entropy, heat capacity, and free energy. The origin of the anharmonic phonon thermodynamics is linked to the electronic structure.Comment: 14 pages, 12 figure

Metabolism of 18:4n-3 (stearidonic acid) and 20:4n-3 in salmonid cells in culture and inhibition of the production of prostaglandin F2alpha (PGF2alpha) from 20:4n-6 (arachidonic acid)

Arachidonic acid (AA; 20:4n-6) is the precursor of a range of highly biologically active derivatives, collectively termed eicosanoids, including prostaglandins, thromboxanes, leukotrienes and lipoxins, that act as autocrine hormones regulating many physiological processes including haemostasis, reproduction, immune and inflammatory responses. Eicosapentaenoic (EPA; 20:5n-3) and dihomo-γ-linolenic (20:3n-6) acids modulate eicosanoid metabolism by both inhibiting the conversion of AA to eicosanoids whilst simultaneously being converted to eicosanoids with different, often attenuated, properties compared to their AA homologues. Eicosatetraenoic acid (20:4n-3) is a naturally occurring C20 polyunsaturated fatty acid (PUFA), present in fish oil at levels of around 1-2%, that has been suggested to be the active metabolite responsible for the anti-inflammatory effects of plant oils containing stearidonic acid (18:4n-3). However, the biochemical properties of 20:4n-3 in terms of cellular biology have rarely been investigated, partly due to difficulties in obtaining the fatty acid in high purity. In this paper, we describe methods for the medium scale laboratory preparation of high purity 20:4n-3, and investigate its metabolism in fish cell culture systems which normally contain significant amounts of n-3 PUFA. Thus the incorporation and metabolism of 18:4n-3 and 20:4n-3, and their distribution in phospholipid classes was studied in an established cell line from Atlantic salmon (Salmo salar) (AS), and the effects of 20:4n-3 on eicosanoid production studied in freshly isolated macrophages from rainbow trout (Oncorhynchus mykiss). Both 18:4n-3 and 20:4n-3 were preferentially esterified into phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine in contrast with the accumulation of AA in phosphatidylinositol. Incorporated 18:4n-3 was readily converted to 20:4n-3, and both fatty acids were further desaturated and elongated to EPA and 22:5n-3 but not 22:6n-3. Supplementation with 20:4n-3 decreased the conversion of AA into prostaglandins, as demonstrated by the decreased levels of PGF2α produced in trout macrophages supplemented with 20:4n-3 and AA compared to cells supplemented with AA alone. In addition, 20:4n-3 was converted into eicosanoids in fish cells as indicated by the presence of Δ17,18 12-HETE, Δ17,18 PGE1 and Δ17,18 PGF1α in extracts from rainbow trout macrophages incubated with 20:4n-3

Material and Seismic Assessment of the Great House at Casa Grande Ruins National Monument, Arizona

The authors characterized earthen wall materials and plasters in a mid-fourteenth-century Hohokam great house at Casa Grande Ruins National Monument (Arizona) and assessed the seismic susceptibility of its puddled earth walls. Characterization included determining the microstructure, microcomposition, porosity, aggregate mineralogy, and identification of phases in the binding matrix for each of 36 samples and reconstructing plaster technologies, including material selection, preparation, and application sequences. Findings support the ideas that earthen materials were manipulated to optimize their performance to suit the unique site conditions and needs of the ancient people using the structure and included finishes that were unusual in southwestern sites from this time period. By using a new set of tools that integrate the complicated geometry of individual wall segments as captured in light detection and ranging (LiDAR) scans (models were generated in Rhino version 5) with the dynamic analysis of rocking mechanisms (tools for this analysis were developed in Rhino), seismic collapse assessment was used to identify the most vulnerable parts of the building to earthquake loading and provided an initial evaluation of the seismic overturning capacity of these wall segments

The effect of age on emotion processing in individuals with mood disorders and in healthy individuals

Copyright \ua9 2024 Gray, Moot, Frampton, Douglas, Gallagher, Jordan, Carter, Inder, Crowe, McIntosh and Porter. Introduction: Emotion processing is an essential part of interpersonal relationships and social interactions. Changes in emotion processing have been found in both mood disorders and in aging, however, the interaction between such factors has yet to be examined in detail. This is of interest due to the contrary nature of the changes observed in existing research - a negativity bias in mood disorders versus a positivity effect with aging. It is also unclear how changes in non-emotional cognitive function with aging and in mood disorders, interact with these biases. Methods and results: In individuals with mood disorders and in healthy control participants, we examined emotional processing and its relationship to age in detail. Data sets from two studies examining facial expression recognition were pooled. In one study, 98 currently depressed individuals (either unipolar or bipolar) were compared with 61 healthy control participants, and in the other, 100 people with bipolar disorder (in various mood states) were tested on the same facial expression recognition task. Repeated measures analysis of variance was used to examine the effects of age and mood disorder diagnosis alongside interactions between individual emotion, age, and mood disorder diagnosis. A positivity effect was associated with increasing age which was evident irrespective of the presence of mood disorder or current mood episode. Discussion: Results suggest a positivity effect occurring at a relatively early age but with no evidence of a bias toward negative emotions in mood disorder or specifically, in depressed episodes. The positivity effect in emotional processing in aging appears to occur even within people with mood disorders. Further research is needed to understand how this fits with negative biases seen in previous studies in mood disorders

Boosted Fast Flux Loop Alternative Cooling Assessment

The Gas Test Loop (GTL) Project was instituted to develop the means for conducting fast neutron irradiation tests in a domestic radiation facility. It made use of booster fuel to achieve the high neutron flux, a hafnium thermal neutron absorber to attain the high fast-to-thermal flux ratio, a mixed gas temperature control system for maintaining experiment temperatures, and a compressed gas cooling system to remove heat from the experiment capsules and the hafnium thermal neutron absorber. This GTL system was determined to provide a fast (E > 0.1 MeV) flux greater than 1.0E+15 n/cm2-s with a fast-to-thermal flux ratio in the vicinity of 40. However, the estimated system acquisition cost from earlier studies was deemed to be high. That cost was strongly influenced by the compressed gas cooling system for experiment heat removal. Designers were challenged to find a less expensive way to achieve the required cooling. This report documents the results of the investigation leading to an alternatively cooled configuration, referred to now as the Boosted Fast Flux Loop (BFFL). This configuration relies on a composite material comprised of hafnium aluminide (Al3Hf) in an aluminum matrix to transfer heat from the experiment to pressurized water cooling channels while at the same time providing absorption of thermal neutrons. Investigations into the performance this configuration might achieve showed that it should perform at least as well as its gas-cooled predecessor. Physics calculations indicated that the fast neutron flux averaged over the central 40 cm (16 inches) relative to ATR core mid-plane in irradiation spaces would be about 1.04E+15 n/cm2-s. The fast-to-thermal flux ratio would be in excess of 40. Further, the particular configuration of cooling channels was relatively unimportant compared with the total amount of water in the apparatus in determining performance. Thermal analyses conducted on a candidate configuration showed the design of the water coolant and Al-Hf alloy heat sink system is capable of maintaining all system components below their maximum temperature limits. The maximum temperature of this conduction cooling system, 224.2°C (435.6 °F) occurs in a small, localized region in the heat sink structure near the core mid-plane. The total coolant flow rate requirement for this configuration is 207 L/min (54.7 gpm). The calculated Flow Instability Ratio and Departure from Nucleate Boiling Ratio for this configuration under nominal conditions are 6.5 and 8.0, respectively, which safely exceed the minimum values of 2.0. Materials and fabrication issues inspection revealed that the neutron absorber would probably best be made from powdered Al3Hf mixed with aluminum powder and extruded or hot isostatically pressed. Although Al3Hf has not been specifically studied extensively, its mechanical and chemical properties should be very much like Al3Zr, which has been studied. Its behavior under irradiation should be very satisfactory, and resistance to corrosion will be investigated to a limited extent in planned miniplate irradiation tests in ATR. Pressurized water systems needed to effect heat removal are already available in the ATR complex, and mixed gas temperature control systems needed to trim experiment temperatures have been engineered and need only be fabricated and installed. In sum, it appears the alternately cooled configuration arrived at can be very successful. The cost estimate for this configuration indicates t

Measuring the non-thermal pressure in early type galaxy atmospheres: A comparison of X-ray and optical potential profiles in M87 and NGC1399

We compare the gravitational potential profiles of the elliptical galaxies NGC 4486 (M87) and NGC 1399 (the central galaxy in the Fornax cluster) derived from X-ray and optical data. This comparison suggests that the combined contribution of cosmic rays, magnetic fields and micro-turbulence to the pressure is ~10% of the gas thermal pressure in the cores of NGC 1399 and M87, although the uncertainties in our model assumptions (e.g., spherical symmetry) are sufficiently large that the contribution could be consistent with zero. In the absence of any other form of non-thermal pressure support, these upper bounds translate into upper limits on the magnetic field of ~10-20 muG at a distance of 1'-2' from the centers of NGC1399 and M87. We show that these results are consistent with the current paradigm of cool cluster cores, based on the assumption that AGN activity regulates the thermal state of the gas by injecting energy into the intra-cluster medium. The limit of ~10-20% on the energy density in the form of relativistic protons applies not only to the current state of the gas, but essentially to the entire history of the intra-cluster medium, provided that cosmic ray protons evolve adiabatically and that their spatial diffusion is suppressed.Comment: Accepted for MNRAS. 19 pages; 14 figures; expanded version in response to comments from the refere

Introduction to Random Matrices

These notes provide an introduction to the theory of random matrices. The central quantity studied is $\tau(a)= det(1-K)$ where $K$ is the integral operator with kernel 1/\pi} {\sin\pi(x-y)\over x-y} \chi_I(y). Here $I=\bigcup_j(a_{2j-1},a_{2j})$ and $\chi_I(y)$ is the characteristic function of the set $I$. In the Gaussian Unitary Ensemble (GUE) the probability that no eigenvalues lie in $I$ is equal to $\tau(a)$. Also $\tau(a)$ is a tau-function and we present a new simplified derivation of the system of nonlinear completely integrable equations (the $a_j$'s are the independent variables) that were first derived by Jimbo, Miwa, M{\^o}ri, and Sato in 1980. In the case of a single interval these equations are reducible to a Painlev{\'e} V equation. For large $s$ we give an asymptotic formula for $E_2(n;s)$, which is the probability in the GUE that exactly $n$ eigenvalues lie in an interval of length $s$.Comment: 44 page

The cultural side of value creation

The question of how organizations create value has become a central question for understanding inter-firm competition and performance differentials. Much of the work on the topic emphasizes the importance of technological innovation for improving operational efficiency and/or product functionality . Accordingly, much of the work in the area has focused on understanding the development of technological capabilities and the dynamics of competition among different technologies. Whereas this line of research has contributed greatly to our understanding of value creation through technology performance improvement, it has also left unexplored the strategies for differentiating products on the basis of their cultural significance. Yet, research in a wide variety of disciplines ranging from anthropology, to cultural sociology, and consumer behavior shows that consumers value products not only for their functional and technical performance, but also for their cultural meanings. The infusion of products with cultural meanings enables consumers to use these products to make statements about their personal and social identity and status. It is therefore well understood that consumers derive value not only from what products do (functional value), but also from what they signify in a given social group (symbolic value). While strategy scholars recognize that product meanings are a source of differentiation and generate price premia (Porter, 1980), they also tend to view the activities that generate them – e.g. branding – as a part of the marketing strategy of the firm. More generally, strategy research has been criticized for its reluctance to delve into the demand side of value-creation. Rooted in disciplinary assumptions about atomistic consumers with idiosyncratic preferences, strategy researchers view demand as largely exogenous and ignore its cultural embeddedness in social conventions that define the cultural meanings of objects and shape consumption choices. As a result, they have given limited attention to the question of how firms can strategically manage the symbolic value of their products. In this paper we propose a cultural perspective on value creation that can direct strategic organization research toward the systematic investigation of how producers engage with the cultural meaning systems that supply frameworks for interpretation and valuation of goods. To guide research in this direction we first discuss how products acquire cultural significance and then outline three core implications of these ideas for the strategy and organization of firms. First, we discuss how recognizing the cultural significance of products shifts attention from technological innovation that alters product functionality to cultural innovation that alters their cultural significance. Second, we explain the need to develop distinct cultural resources that enable firms to identify and exploit opportunities for cultural innovation. Third, we draw attention to the need for cultural intent defined as developing an explicit strategy for utilizing cultural resources to achieve specific cultural positioning for the firm’s products

Report to the DOE on the “Crud II” project

This report documents SEM, TEM, and chemical analyses from crud samples from a commercially operating reactor