Reswitching and Decreasing Demand for Capital in a Model with a Continuum of Linear Techniques

We consider a model of production with a continuum of linear techniques and examine the related choice of technique and shape of the demand for capital schedule. The primary conclusion regards the possibility of a decreasing demand for capital schedule combined with reswitching and reverse capital deepening.Production, continuum linear techniques.

The Hicks-Malinvaud average period of production and ‘marginal productivity’: a critical assessment

Malinvaud (2003) observed that once techniques are ranked according to Hick’s concept of average period for a given rate of interest, a rise in the latter entails the use of a technique with a shorter average period. After a reconstruction of Malinvaud’s argument, it is shown that the result is far less encouraging for neoclassical theory than it might seem. The most important problem is not the fact that change in the interest rate affects the average period associated with a technique, despite the concern this aroused in Hicks and Malinvaud, but rather that it affects the ranking of techniques.Average period of production, capital, interest rate, Wicksell.

RESWITCHING AND DECREASING DEMAND FOR CAPITAL

We consider a model of production with a continuum of linear techniques and examine the related choice of technique and shape of the demand for capital schedule. The primary conclusion regards the possibility of a decreasing demand for capital schedule combined with reswitching and reverse capital deepening.Capital Theory, Linear Activities of Production, Theory of Value

Jahn-Teller, Charge and Magnetic Ordering in half-doped Manganese Oxides

The phase diagram of half-doped manganite systems of formula A_{0.5}A'_{0.5}MnO_3 is investigated within a single-orbital model incorporating magnetic double-exchange and superexchange, together with intersite Coulomb and electron-lattice interactions. Strong Jahn-Teller and breathing mode deformations compete together and result in shear lattice deformations. The latters stabilize the charge-ordered CE-type phase, which undergo first-order transitions with temperature or magnetic field to either Ferromagnetic metallic or Paramagnetic insulating phases. An essential feature is the self-consistent screening of Coulomb and electron-phonon interactions in the ferromagnetic phase.Comment: 10 pages, six figures (eps files) +two class file

A remark on the supposed equivalence between complete markets and perfect foresight hypothesis

We consider a sequential equilibrium model over two periods, during the first of which agents have perfect information and their expectations are formed as if there were complete future markets. We show that, in the second period, equilibrium prices may well be different from those expected, without any unexpected change having occurred. This result highlights a lack of correspondence between the perfect foresight hypothesis and that of complete markets.Arrow-Debreu equilibrium, Complete markets, Sequential equilibrium, Perfect foresight, Indeterminacy

Signatures of polaronic charge ordering in optical and dc conductivity using dynamical mean field theory

We apply dynamical mean field theory to study a prototypical model that describes charge ordering in the presence of both electron-lattice interactions and intersite electrostatic repulsion between electrons. We calculate the optical and d.c. conductivity, and derive approximate formulas valid in the limiting electron-lattice coupling regimes. In the weak coupling regime, we recover the usual behavior of charge density waves, characterized by a transfer of spectral weight due to the opening of a gap in the excitation spectrum. In the opposite limit of very strong electron-lattice coupling, instead, the charge ordering transition is signaled by a global enhancement of the optical absorption, with no appreciable spectral weight transfer. Such behavior is related to the progressive suppression of thermally activated charge defects taking place below the critical temperature. At intermediate values of the coupling within the polaronic regime, a complex behavior is obtained where both mechanisms of transfer and enhancement of spectral weight coexist.Comment: 1 figure added, illustrating the optical sum rul

2D-3D registration of CT vertebra volume to fluoroscopy projection: A calibration model assessment (doi:10.1155/2010/806094)

This study extends a previous research concerning intervertebral motion registration by means of 2D dynamic fluoroscopy to obtain a more comprehensive 3D description of vertebral kinematics. The problem of estimating the 3D rigid pose of a CT volume of a vertebra from its 2D X-ray fluoroscopy projection is addressed. 2D-3D registration is obtained maximising a measure of similarity between Digitally Reconstructed Radiographs (obtained from the CT volume) and real fluoroscopic projection. X-ray energy correction was performed. To assess the method a calibration model was realised a sheep dry vertebra was rigidly fixed to a frame of reference including metallic markers. Accurate measurement of 3D orientation was obtained via single-camera calibration of the markers and held as true 3D vertebra position; then, vertebra 3D pose was estimated and results compared. Error analysis revealed accuracy of the order of 0.1 degree for the rotation angles of about 1?mm for displacements parallel to the fluoroscopic plane, and of order of 10?mm for the orthogonal displacement.<br/

Alcune osservazioni sulla forma delle curve di domanda e offerta di capitale

ABSTRACT Some Remarks on the Shape of the Capital Demand and Supply Curves. The present paper is aimed at discussing some results concerning the choice of techniques and the capital theory in order to shed some light on aspects that might cause, and sometimes caused, a misunderstanding. We will show, in particular, that the shape of the demand for capital schedule does not, in general, reveal the presence (or the lack) of phenomena like reverse capital deepening and reswitching. The erroneous belief that the shape of the demand for capital schedule alone were sufficient to foresee possible instability problems seems to come from a conception of capital supply as a given value magnitude, as it is in Wicksell. Therefore, we will argue for the advisability of keeping the difficulties concerning the demand for capital side apart from those concerning its supply side. A method allowing this separation is also provided. Alcune Osservazioni sulla Forma delle Curva di Domanda e Offerta di Capitale. In questo scritto si discutono alcuni risultati riguardanti la scelta delle tecniche e la teoria del capitale con lo scopo di far chiarezza su certi aspetti che potrebbero prestarsi, e talvolta si sono prestati, a fraintendimenti. Si mostrerà, in particolare, che la forma della curva della domanda di capitale in valore non è, in generale, rivelatrice della presenza o meno dei fenomeni di inversione dell’intensità capitalistica e ritorno delle tecniche. L’erroneo convincimento che il solo andamento della curva di domanda di capitale sia sufficiente per prevedere possibili problemi di instabilità sembra derivare da una concezione dell’offerta di capitale come un dato ammontare di valore, come in Wicksell. Così, si sosterrà l’opportunità di tenere distinte le difficoltà riguardanti il lato della domanda di capitale, da quelle riguardanti il lato dell’offerta. Si proporrà inoltre un metodo che consenta di isolare le prime.

La rendita assoluta di Marx e le equazioni di prezzo di Sraffa

In questo scritto si discutono tre questioni relative alla teoria della rendita assoluta: 1) una possibile reinterpretazione delle ipotesi che Marx pone alla base della sua teoria della rendita assoluta; 2) le differenze tra la rendita assoluta e la rendita da monopolio; 3) la possibilità di concepire la rendita assoluta in modo tale da poterne tener conto nella determinazione dei prezzi relativi attraverso il sistema di equazioni di Sraffa.

Towards a consistent eddy-covariance processing: An intercomparison of EddyPro and TK3

A comparison of two popular eddy-covariance software packages is presented, namely, EddyPro and TK3. Two approximately 1-month long test data sets were processed, representing typical instrumental setups (i.e., CSAT3/LI-7500 above grassland and Solent R3/LI-6262 above a forest). The resulting fluxes and quality flags were compared. Achieving a satisfying agreement and understanding residual discrepancies required several iterations and interventions of different nature, spanning from simple software reconfiguration to actual code manipulations. In this paper, we document our comparison exercise and show that the two software packages can provide utterly satisfying agreement when properly configured. Our main aim, however, is to stress the complexity of performing a rigorous comparison of eddy-covariance software. We show that discriminating actual discrepancies in the results from inconsistencies in the software configuration requires deep knowledge of both software packages and of the eddy-covariance method. In some instances, it may be even beyond the possibility of the investigator who does not have access to and full knowledge of the source code. Being the developers of EddyPro and TK3, we could discuss the comparison at all levels of details and this proved necessary to achieve a full understanding. As a result, we suggest that researchers are more likely to get comparable results when using EddyPro (v5.1.1) and TK3 (v3.11) – at least with the setting presented in this paper – than they are when using any other pair of EC software which did not undergo a similar cross-validation. As a further consequence, we also suggest that, to the aim of assuring consistency and comparability of centralized flux databases, and for a confident use of eddy fluxes in synthesis studies on the regional, continental and global scale, researchers only rely on software that have been extensively validated in documented intercomparisons