The pinning quantum phase transition in a Tonks Girardeau gas: diagnostics by ground state fidelity and the Loschmidt echo

We study the pinning quantum phase transition in a Tonks-Girardeau gas, both in equilibrium and out-of-equilibrium, using the ground state fidelity and the Loschmidt echo as diagnostic tools. The ground state fidelity (GSF) will have a dramatic decrease when the atomic density approaches the commensurate density of one particle per lattice well. This decrease is a signature of the pinning transition from the Tonks to the Mott insulating phase. We study the applicability of the fidelity for diagnosing the pinning transition in experimentally realistic scenarios. Our results are in excellent agreement with recent experimental work. In addition, we explore the out of equilibrium dynamics of the gas following a sudden quench with a lattice potential. We find all properties of the ground state fidelity are reflected in the Loschmidt echo dynamics i.e., in the non equilibrium dynamics of the Tonks-Girardeau gas initiated by a sudden quench of the lattice potential

The Composition of Coarse Sediment in Basal Upper Old Red Sandstone Alluvial Fan Conglomerates of the Northwest Midland Valley, Scotland: A Provenance Study

A provenance investigation of coarse detritus (sand to boulder size) associated with basal Upper Old Red Sandstone (Upper Devonian) alluvial fans has been carried out in the northwest Midland Valley of Scotland. Detailed Petrographic, XRD and SEM studies of sandstones (lithic arenites) interbedded with conglomerate units confirm previously suspected compositional differences for three localities, Portencross, Wemyss Bay and Roseneath along the Firth of Clyde Upper ORS dispersal system. Much of this detritus is interpreted as first cycle and reflects abrupt compositional changes in essentially metamorphic basement lithologies beneath the northwest Midland Valley. These changes may be summarised as increasing metamorphic grade towards the north/northwest ranging from low greenschist facies in the southeast to garnet grade in the northwest. This is combined with a trend from a significant basic plutonic/volcanic input to a more acid igneous component in a similar direction. A substantial amount of reworking of older sediment is also implied for the entire region; characteristic lithic fragments suggest sediment of at least Silurian to early Devonian age contributed detritus to the developing Upper ORS basin. Textural investigation of sand sized material indicates immaturity, and no significant decrease in grain size for these alluvial sediments in the direction of supposed palaeoflow (S/SW-N/NE). This has also been detected in the cobble-boulder size conglomerate material. This, together with the unique compositional assemblages, reinforces the view that the Upper ORS basin in the Firth of Clyde subsided diachronously with earlier deposits overlain by younger sediments as the basin margins receeded towards the south/southwest. Major oxide and trace element analysis of southerly derived intermediate and acid igneous boulders at Roseneath, the most northerly of the localities investigated, reveals that they have clear affinities with Lower Devonian (c410 Ma) granitoids intruded into the SW Highlands Dalradian metamorphic terrain some 30-40+km to the north. Many granodiorite clasts also display evidence of incipient Cu mineralization, a feature also recognised in the SW Highlands igneous suite. Preliminary geochemical and petrographical analysis of the metamorphic clasts at Roseneath also reveals many significant similarities with lithologies of similar metamorphic grade in the SW Highlands 30-40km to the north. In contrast, however, Rb-Sr isotopic data obtained from co-magmatic granodioritic boulders suggests an emplacement age of at least 516+/-5Ma for an intrusion whose initial 87Sr/86Sr ratio was of the order of 0.704. This significantly predates the SW Highlands granites although the initial strontium ratio together with trace element features implies that the 'Roseneath pluton' and many SW Highlands granites must have shared a common origin in the deep crust or mantle; the latter being preferred on account of a large (?) Grenville inherited zircon component as detected by U-Pb isotopic analysis. The paradoxical nature of much of the evidence obtained in this study makes conclusions regarding provenance of the basal Upper ORS difficult to draw. The simplest based model for the northwest Midland Valley may have parallels in westward extension of the Midland Valley in Ireland (Connemara) where Dalradian and largely undeformed Cambro-Ordovician plutonic lithologies are combined in a complex thrust related mixed terrain

Rebalancing the board's agenda

Since 2002, the activities of corporate boards have been dominated by the governance agenda. In Europe - to an even greater degree than the United States - governance codes have proliferated. This paper examines the resulting imbalance, where compliance with codes of conduct threatens to overwhelm the board's primary responsibility, i.e. the creation of wealth. We consider a model of board processes that starts with four key roles: setting direction, marshalling resources, controlling and reporting, and evaluating and enhancing for the next cycle. "We must urgently bring back some pragmatism to corporate governance . . . And if we want principles, not detailed rules that try to pre-empt all the eventualities a lawyer can think of." Peter Brabeck-Letmathe, CEO, Nestlé SA. The governance agenda has rightly drawn attention to the work of board committees and the question of the independence of mind directors need to show. But it may have diverted focus from three questions that ought to figure more prominently in the board's work: • How should the board apportion its work between compliance, risk assessment and setting strategic directions? • How do directors become determine when to focus on risk-mitigation and when to encourage strategic risk-taking? • In face of greater personal accountability for governance compliance, where do they draw the line between their role overseeing management and interfering with management's responsibilities? ABSTRACT FROM AUTHOR Copyright of Journal of General Management is the property of Braybrooke Press Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract

Work and Quantum Phase Transitions: Is there Quantum Latency?

We study the physics of quantum phase transitions from the perspective of non-equilibrium thermodynamics. For first order quantum phase transitions, we find that the average work done per quench in crossing the critical point is discontinuous. This leads us to introduce the quantum latent work in analogy with the classical latent heat of first order classical phase transitions. For second order quantum phase transitions the irreversible work is closely related to the fidelity susceptibility for weak sudden quenches of the system Hamiltonian. We demonstrate our ideas with numerical simulations of first, second, and infinite order phase transitions in various spin chain models.Comment: accepted in PR

Bridging the gap through Rényi divergences

The work performed on or extracted from a nonautonomous quantum system described by means of a two-point projective-measurement approach is a stochastic variable. We show that the cumulant generating function of work can be recast in the form of quantum Rényi-α divergences, and by exploiting the convexity of this cumulant generating function, derive a single-parameter family of bounds for the first moment of work. Higher order moments of work can also be obtained from this result. In this way, we establish a link between quantum work statistics in stochastic approaches and resource theories for quantum thermodynamics, a theory in which Rényi-α divergences take a central role. To explore this connection further, we consider an extended framework involving a control switch and an auxiliary battery, which is instrumental to reconstructing the work statistics of the system. We compare and discuss our bounds on the work distribution to findings on deterministic work studied in resource-theoretic settings

Quantum work statistics and resource theories: bridging the gap through Renyi divergences

The work performed on or extracted from a non-autonomous quantum system described by means of a two-point projective-measurement approach takes the form of a stochastic variable. We show that the cumulant generating function of work can be recast in the form of quantum Renyi divergences, and by exploiting convexity of this cumulant generating function, derive a single-parameter family of bounds for the first moment of work. Higher order moments of work can also be obtained from this result. In this way, we establish a link between quantum work statistics in stochastic approaches on the one hand and resource theories for quantum thermodynamics on the other hand, a theory in which Renyi divergences take a central role. To explore this connection further, we consider an extended framework involving a control switch and an auxiliary battery, which is instrumental to reconstruct the work statistics of the system. We compare and discuss our bounds on the work distribution to findings on deterministic work studied in resource theoretic settings.Comment: 8 pages, minor changes, references adde

Direct detection of bound ammonium ions in the selectivity filter of ion channels by solid-state NMR.

The flow of ions across cell membranes facilitated by ion channels is an important function for all living cells. Despite the huge amount of structural data provided by crystallography, elucidating the exact interactions between the selectivity filter atoms and bound ions is challenging. Here, we detect bound 15 N-labeled ammonium ions as a mimic for potassium ions in ion channels using solid-state NMR under near-native conditions. The non-selective ion channel NaK showed two ammonium peaks corresponding to its two ion binding sites, while its potassium-selective mutant NaK2K that has a signature potassium- selective selectivity filter with four ion binding sites gave rise to four ammonium peaks. Ions bound in specific ion binding sites were identified based on magnetization transfer between the ions and carbon atoms in the selectivity filters. Magnetization transfer between bound ions and water molecules revealed that only one out of four ions in the selectivity filter of NaK2K is in close contact with water, which is in agreement with the direct knock-on ion conduction mechanism where ions are conducted through the channel by means of direct interactions without water molecules in between. Interestingly, the potassium-selective ion channels investigated here (NaK2K and, additionally, KcsA-Kv1.3) showed remarkably different chemical shifts for their bound ions, despite having identical amino acid sequences and crystal structures of their selectivity filters. Molecular dynamics simulations show similar ion binding and conduction behavior between ammonium and potassium ions and identify the origin of the differences between the investigated potassium channel

Trust and control interrelations: New perspectives on the trust control nexus

This article is the post-print version of the published article that may be accessed at the link below. Copyright @ 2007 Sage Publications.This article introduces the special issue on New Perspectives on the Trust-Control Nexus in Organizational Relations. Trust and control are interlinked processes commonly seen as key to reach effectiveness in inter- and intraorganizational relations. The relation between trust and control is, however, a complex one, and research into this relation has given rise to various and contradictory interpretations of how trust and control relate. A well-known discussion is directed at whether trust and control are better conceived as substitutes, or as complementary mechanisms of governance. The articles in this special issue bring the discussion on the relationship between both concepts a step further by identifying common factors, distinctive mechanisms, and key implications relevant for theory building and empirical research. By studying trust and control through different perspectives and at different levels of analysis, the articles provide new theoretical insights and empirical evidence on the foundations of the trust-control interrelations

Regulating CCTV? : We can't solve problems by using the same kind of thinking we used when we created them

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