A new 3-D polymeric spin transition compound: [tris(1,4-bis-(tetrazol-1-yl) butane-N1,N1′)iron(II)] bis(perchlorate)

A series of novel polymeric compounds of formula [M(btzb)3][ClO4]2 (Mll = Fe, Ni or Cu) with btzb = 1,4-bis-(tetrazol-1-yl)butane have been prepared and their physical properties investigated. The btzb ligand has been prepared and its crystal structure determined, together with a tentative crystal structure of the 3-D compound [Fe(btzb)3][ClO4]2. The model of the latter shows two symmetry-related, interpenetrating Fe-btzb networks in which the iron(II) ions approach each other as close as 8.3 and 9.1 Å. This supramolecular catenane undergoes a sharp thermal spin transition around 160 K with hysteresis (20 K) along with a pronounced thermochromic effect. The spin crossover behaviour has been followed by magnetic, DSC, optical spectroscopy and 57Fe Mössbauer spectroscopy measurements. Irradiation with green light at low temperature leads to population of the metastable high-spin state for the thermally active iron(ll) ions. The nature of the spin crossover behaviour has been discussed in detail.

CuII chain compound showing a ferromagnetic coupling through triple N1,N2-1,2,4-triazole bridges

[Cu(hyetrz)3](CF3SO3)2·H2O [hyetrz = 4-(2′-hydroxyethyl)-1,2,4-triazole] represents the first structurally characterised ferromagnetically coupled CuII chain compound containing triple N1,N2-1,2,4-triazole bridges. catena-[μ-Tris{4-(2′-hydroxyethyl)-1,2,4-triazole-N1,N2}copper(II)] bis(trifluoromethanesulfonate) hydrate (C14H23F6S2O10CuN9) crystallises in the triclinic space group Pl, a = 13.54(3), b = 14.37(3), c = 15.61(4) Å, α = 95.9(1), β = 104.9(1), γ = 106.5(1)°, V = 2763(11) Å3, Z = 4 (CuII units). The CuII ions are linked by triple N1,N2-1,2,4-triazole bridges yielding an alternating chain with Cu1−Cu2 = 3.8842(4) Å and Cu2−Cu3 = 3.9354(4) Å. Analysis of the magnetic data according to a high-temperature series expansion gives a J value of +1.45(3) cm−1. The nature and the magnitude of the ferromagnetic exchange have been discussed on the basis of the structural features. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

Crystal structure and physical properties of the new linear chain compound [Cu(1,2-bis(tetrazol-1-yl)ethane)3](ClO4)2

The synthesis and crystal structure of a novel one-dimensional Cu(II) compound [Cu(1,2-bis(tetrazol-1-yl)ethane)3](ClO4)2 are described. The single-crystal X-ray structure determination was carried out at 298 K. The molecular structure consists of a linear chain in which the Cu(II) ions are linked by three N4,N4' coordinating bis(tetrazole) ligands in syn conformation. The Cu(II) ions are in a Jahn-Teller distorted octahedral environment (Cu(1)-N(11)=2.034(2) Å, Cu(1)-N(21)=2.041(2) Å and Cu(1)-N(31)=2.391(2) Å). The Cu⋯Cu separations are 7.420(3) Å.

Acousto-optic effect in microstructured polymer fiber bragg gratings:simulation and experimental overview

A fine control of the microstructured polymer fiber Bragg grating spectrum properties, such as maximum reflected power and 3-dB bandwidth, through acousto-optic modulation is presented. For simulation purposes, the device is modelled as a single structure, comprising a silica horn and a fiber Bragg grating. For similar sized structures a good correlation between the numerical results and the experimental data is obtained, allowing the strain field to be completely characterized along the whole structure. It is also shown that the microstructured polymer fiber Bragg grating requires less effort from the piezoelectric actuator to produce modification in the grating spectrum when compared with a silica fiber Bragg grating. This technique has potential to be applied on tunable optical filters and tunable cavities for photonic applications.

Linking Ecology and Economics for Ecosystem Management

This article outlines an approach, based on ecosystem services, for assessing the trade-offs inherent in managing humans embedded in ecological systems. Evaluating these trade-offs requires an understanding of the biophysical magnitudes of the changes in ecosystem services that result from human actions, and of the impact of these changes on human welfare. We summarize the state of the art of ecosystem services-based management and the information needs for applying it. Three case studies of Long Term Ecological Research (LTER) sites--coastal, urban, and agricultural-- illustrate the usefulness, information needs, quantification possibilities, and methods for this approach. One example of the application of this approach, with rigorously established service changes and valuations taken from the literature, is used to illustrate the potential for full economic valuation of several agricultural landscape management options, including managing for water quality, biodiversity, and crop productivity.

Exploring Employee Engagement Among Three Non-Salaried Employees: A Phenomenological Study

This exploratory empirical phenomological study looks at employee engagement using Kahn (1990) and Maslow’s (1970) motivational theories to understand the experience of non-salaried employees. This study finds four themes that seem to affect employee engagement: work environment, employee’s supervisor, individual characteristics of the employee, and opportunity for learning.

An examination of psychological meaningfulness, safety, and availability as the underlying mechanisms linking job features and personal characteristics to work engagement

The present study tested a nomological net of work engagement that was derived from its extant research. Two of the main work engagement models that have been presented and empirically tested in the literature, the JD-R model and Kahn's model, were integrated to test the effects that job features and personal characteristics can have on work engagement through the psychological conditions of meaningfulness, safety, and availability. In this study, safety refers to psychological perceptions of safety and not workplace safety behaviors. The job features that were tested in this model included person-job fit, autonomy, co-worker relations, supervisor support, procedural justice, and interactional justice, while the personal characteristics consisted of self-consciousness, self-efficacy, extraversion, and neuroticism. Thirty-four hypotheses and a conceptual model were tested in order to establish the viability of this nomological net of work engagement in which it was expected that meaningfulness would mediate the relationships between job features and work engagement, safety would mediate the relationships that job features and personal characteristics have with work engagement, and availability (physical, emotional, and cognitive resources) would mediate the relationships that personal characteristics have with work engagement. Furthermore, analyses were run in order to determine the factor structure of work engagement, assess whether or not it exhibits differential validity from organizational commitment and job satisfaction, and confirm that it is positively related to the outcome variable of organizational citizenship behavior (OCB). The final sample consisted of 500 workers from an online labor market who responded to a questionnaire composed of measures of all constructs included in this study. Findings show that work engagement is best represented as a three-factor construct, composed of vigor, dedication and absorption. Furthermore, support was found for the distinction of work engagement from the related constructs of organizational commitment and job satisfaction. With regard to the proposed model, meaningfulness proved to be the strongest predictor of work engagement. Results show that it partially mediates the relationships that all job features have with work engagement. Safety proved to be a partial mediator of the relationships that autonomy, co-worker relations, supervisor support, procedural justice, interactional justice, and self-efficacy have with work engagement, and fully mediate the relationship between neuroticism and work engagement. Findings also show that availability partially mediates the positive relationships that extraversion and self-efficacy have with work engagement, and fully mediates the negative relationship that neuroticism has with work engagement. Finally, a positive relationship was found between work engagement and OCB. Research and organizational implications are discussed.

the Art and Science Museums and Mindseums of the Future

Ted Kahn, co-founder, President, and CEO of DesignWorlds for Learning, Inc. speaks about his research and practice in developing uses for interactive learning technologies in museums, schools, and workplaces.

Arsène Darmesteter : professeur à la Faculté des lettres de Paris ; né à Château-Salins (Meurthe), le 5 janvier 1846 ; mort à Paris le 16 novembre 1888

[Zadoc Kahn ...]

Ghrelin suppresses glucose-stimulated insulin secretion and deteriorates glucose tolerance in healthy humans.

OBJECTIVE: The orexigenic gut hormone ghrelin and its receptor are present in pancreatic islets. Although ghrelin reduces insulin secretion in rodents, its effect on insulin secretion in humans has not been established. The goal of this study was to test the hypothesis that circulating ghrelin suppresses glucose-stimulated insulin secretion in healthy subjects. RESEARCH DESIGN AND METHODS: Ghrelin (0.3, 0.9 and 1.5 nmol/kg/h) or saline was infused for more than 65 min in 12 healthy patients (8 male/4 female) on 4 separate occasions in a counterbalanced fashion. An intravenous glucose tolerance test was performed during steady state plasma ghrelin levels. The acute insulin response to intravenous glucose (AIRg) was calculated from plasma insulin concentrations between 2 and 10 min after the glucose bolus. Intravenous glucose tolerance was measured as the glucose disappearance constant (Kg) from 10 to 30 min. RESULTS: The three ghrelin infusions raised plasma total ghrelin concentrations to 4-, 15-, and 23-fold above the fasting level, respectively. Ghrelin infusion did not alter fasting plasma insulin or glucose, but compared with saline, the 0.3, 0.9, and 1.5 nmol/kg/h doses decreased AIRg (2,152 +/- 448 vs. 1,478 +/- 2,889, 1,419 +/- 275, and 1,120 +/- 174 pmol/l) and Kg (0.3 and 1.5 nmol/kg/h doses only) significantly (P < 0.05 for all). Ghrelin infusion raised plasma growth hormone and serum cortisol concentrations significantly (P < 0.001 for both), but had no effect on glucagon, epinephrine, or norepinephrine levels (P = 0.44, 0.74, and 0.48, respectively). CONCLUSIONS: This is a robust proof-of-concept study showing that exogenous ghrelin reduces glucose-stimulated insulin secretion and glucose disappearance in healthy humans. Our findings raise the possibility that endogenous ghrelin has a role in physiologic insulin secretion, and that ghrelin antagonists could improve beta-cell function.

Development of a knowledge sharing framework for improving the testing processes in global product development

As identified by Griffin (1997) and Kahn (2012), manufacturing organisations typically improve their market position by accelerating their product development (PD) cycles. One method for achieving this is to reduce the time taken to design, test and validate new products, so that they can reach the end customer before competition. This paper adds to existing research on PD testing procedures by reporting on an exploratory investigation carried out in a UK-based manufacturing plant. We explore the organisational and managerial factors that contribute to the time spent on testing of new products during development. The investigation consisted of three sections, viz. observations and process modelling, utilisation metrics and a questionnaire-based investigation, from which a proposed framework to improve and reduce the PD time cycle is presented. This research focuses specifically on the improvement of the utilisation of product testing facilities and the links to its main internal stakeholders - PD engineers.

What Heraclitus and Parmenides have in common on Reality and Deception

It is usually assumed that Heraclitus is, exclusively, the philosopher of flux, diversity and opposition while Parmenides puts the case for unity and changelessness. However, there is a significant common understanding of things (though in differing contexts), not simply an accidental similarity of understanding. Both philosophers, critically, distinguish two realms: on the one hand, there is the one, common realm, identical for all, which is grasped by the ‘logos that is common’(Heraclitus) or the steady nous (Parmenides) that follows a right method in order to interpret the real. On the other hand, the realm of multiplicity seen and heard by the senses, when interpreted by ‘barbarian souls’, is not understood in its common unity. Analogously, when grasped by the wandering weak nous it does not comprehend the real’s basic unity. In this paper I attempt to defend the thesis that both thinkers claim that the common logos (to put it in Heraclitean terms) or the steady intellect (to say it with Parmenides) grasp and affirm the unity of the real.

Plato on Oblivion. About Memory and Forgetfullness in the Platonic Dialogues

The aim of this paper is to tackle the role of oblivion in the Plato’s dialogues. It takes as work texts the dialogues where the anamnesis doctrine is exposed, and from these writings, but also attending to several other ones, the connexions between oblivion and other Platonic issues, as, e. g., language, memory, experience or love are explored, in order to clarify their relations of mutual dependence. In this way, we attempt to find out in the Platonic oblivion a philosophical sense, which is not disdainful in comparison with the sense and the relevance that the readers of all times have granted to anamnesis; for anamnesis and oblivion are inseparable indeed.

El dinero en la historia del pensamiento económico: la teoría monetaria postkeynesiana y su confrontación con la ortodoxia

Las disputas en torno a determinados aspectos del dinero, como su neutralidad y el carácter endógeno o exógeno de la oferta monetaria, han sido permanentes entre las distintas escuelas de pensamiento y autores, estando su origen, probablemente, en la época de desarrollo del pensamiento escolástico. En este artículo pretendemos, en primer lugar, realizar un recorrido cronológico e histórico sobre el tratamiento científico económico del dinero, para, en segundo lugar, poner sobre la mesa la macroeconomía ortodoxa a la que han dado lugar las interpretaciones al respecto, así como los enfoques alternativos frente a este pensamiento dominante. Finalmente, intentamos poner en valor los desarrollos monetarios post-keynesianos, integrados en lo que denominan “Economía Monetaria de Producción”, confrontándolos con la llamada Nueva Síntesis Neoclásica.

A boron nitride - graphene - C60 heterostructure

We have fabricated a new van-der-Waals heterostructure composed by BN/graphene/C60. We performed transport measurements on the preliminary BN/graphene device finding a sharp Dirac point at the neutrality point. After the deposition of a C60 thin film by thermal evaporation, we have observed a significant n-doping of the heterostructure. This suggests an unusual electron transfer from C60 into the BN/graphene structure. This BN/graphene/C60 heterostructure can be of interest in photovoltaic applications. It can be used to build devices like p-n junctions, where C60 can be easily deposited in defined regions of a graphene junction by the use of a shadow mask. Our results are contrasted with theoretical calculations.