Signatures of Classical Periodic Orbits on a Smooth Quantum System

Gutzwiller's trace formula and Bogomolny's formula are applied to a non--specific, non--scalable Hamiltonian system, a two--dimensional anharmonic oscillator. These semiclassical theories reproduce well the exact quantal results over a large spatial and energy range.Comment: 12 pages, uuencoded postscript file (1526 kb

Had the planet mars not existed: Kepler's equant model and its physical consequences

We examine the equant model for the motion of planets, which has been the starting point of Kepler's investigations before he modified it because of Mars observations. We show that, up to first order in eccentricity, this model implies for each orbit a velocity which satisfies Kepler's second law and Hamilton's hodograph, and a centripetal acceleration with an inverse square dependence on the distance to the sun. If this dependence is assumed to be universal, Kepler's third law follows immediately. This elementary execice in kinematics for undergraduates emphasizes the proximity of the equant model coming from Ancient Greece with our present knowledge. It adds to its historical interest a didactical relevance concerning, in particular, the discussion of the Aristotelian or Newtonian conception of motion

Asymptotic and measured large frequency separations

With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available. So-called global oscillation parameters are inferred to characterize the large sets of stars, to perform ensemble asteroseismology, and to derive scaling relations. The mean large separation is such a key parameter. It is therefore crucial to measure it with the highest accuracy. As the conditions of measurement of the large separation do not coincide with its theoretical definition, we revisit the asymptotic expressions used for analysing the observed oscillation spectra. Then, we examine the consequence of the difference between the observed and asymptotic values of the mean large separation. The analysis is focused on radial modes. We use series of radial-mode frequencies to compare the asymptotic and observational values of the large separation. We propose a simple formulation to correct the observed value of the large separation and then derive its asymptotic counterpart. We prove that, apart from glitches due to stellar structure discontinuities, the asymptotic expansion is valid from main-sequence stars to red giants. Our model shows that the asymptotic offset is close to 1/4, as in the theoretical development. High-quality solar-like oscillation spectra derived from precise photometric measurements are definitely better described with the second-order asymptotic expansion. The second-order term is responsible for the curvature observed in the \'echelle diagrams used for analysing the oscillation spectra and this curvature is responsible for the difference between the observed and asymptotic values of the large separation. Taking it into account yields a revision of the scaling relations providing more accurate asteroseismic estimates of the stellar mass and radius.Comment: accepted in A&

Single-step production of autologous bovine platelet concentrate for clinical applications in cattle.

Platelet concentrate (PC) is an alternative therapy to treat mastitis in dairy cattle and is an alternative treatment for reproduction problems such as endometritis. Unfortunately, double-centrifugation processing methods described are time-consuming, require specialized laboratory equipment, and are usually done in a heterologous way, which risks herd health. To overcome this limitation, we evaluated single-step bovine PC processing methods readily applicable to a farm setting using an autologous conditioned plasma (ACP) production system. We investigated the hematologic findings, cytokines, and growth factors of the obtained PC samples. Autologous conditioned plasma was prepared using whole blood (WB) from 4 cows (group 1) using single-step centrifugation and 16 different processing methods. The 2 protocols that yielded the highest ratio of platelet to white blood cell (WBC) concentration were ACP-1 [720 × g (2,200 rpm), 5 min] and ACP-2 [929 × g (2,500 rpm), 3 min]. They were subsequently reproduced and compared using WB from 8 cows (group 2). Hematologic findings were quantified, IL-1β (cytokine) and growth factors [platelet-derived growth factor (PDGF), transforming growth factor (TGF)-β, bovine fibroblast growth factor (b-FGF)] were measured, and enrichment factors were compared between samples and processing methods. Hematological characteristics and platelet enrichment varied markedly among tested protocols and all were statistically different from WB. Protocol ACP-2 resulted in significantly greater platelet enrichment (mean 169% of WB) than ACP-1 (125% of WB). We found no significant difference between the 2 ACP preparation protocols with regard to leukocyte reduction (7.53-9.75% WBC compared with WB) or growth factor enrichment (124-125% PDGF, 95-100% TGF-β, 102-104% b-FGF, and 56-74% IL-1β compared with WB). In conclusion, both ACP protocols yielded a platelet concentration shown to promote healing for clinical applications in cattle, and the ACP-2 protocol resulted in a greater degree of platelet enrichment. Therefore, this protocol could be used for ACP production for clinical applications in cattle

The Unfulfilled Potential of Data-Driven Decision Making in Agile Software Development

With the general trend towards data-driven decision making (DDDM), organizations are looking for ways to use DDDM to improve their decisions. However, few studies have looked into the practitioners view of DDDM, in particular for agile organizations. In this paper we investigated the experiences of using DDDM, and how data can improve decision making. An emailed questionnaire was sent out to 124 industry practitioners in agile software developing companies, of which 84 answered. The results show that few practitioners indicated a widespread use of DDDM in their current decision making practices. The practitioners were more positive to its future use for higher-level and more general decision making, fairly positive to its use for requirements elicitation and prioritization decisions, while being less positive to its future use at the team level. The practitioners do see a lot of potential for DDDM in an agile context; however, currently unfulfilled

An indole alkaloid from Strychnos erichsonii

Le premier alcaloïde indolique de type vobasine rencontré dans les #Loganiaceae a été isolé des écorces de #Strychnos erichsonii, récoltées en Guyane Française. Sa structure confirmée par cristallographie Rx. (Résumé d'auteur

Impact of the number of fitted Debye-Waller factors on EXAFS fitting

EXAFS fit applied to asymmetric systems may imply the fit of parameters for many scattering paths. We illustrate on some examples how fitting too many independent DWs may lead to incorrect distances and mask some structural details. We question the physical meaning of the fitted DW values and we propose some ideas to avoid this problem

Spring and winter water mass composition in the Brazil-Malvinas Confluence

Hydrographic data of the Confluence 1 cruise collected during austral spring (November 1988) have been analyzed to estimate relative mixing proportions of the various water masses of the Brazil-Malvinas Confluence region using a multiparameter analysis. Seven source water types (SWT) are identified in this region, and all are retained for the analysis: Thermocline Water (TW), Subantarctic Surface Water (SASW), Antarctic Intermediate Water (AAIW), Upper Circumpolar Deep Water (UCDW), North Atlantic Deep Water (NADW), Lower Circumpolar Deep Water (LCDW) and Weddell Sea Deep Water (WSDW). Tracers selected are temperature, salinity, dissolved oxygen and nutrients. Mixing proportions are quantified and plotted along five zonal sections at 35.4, 36.5, 37.9, 41 and 41.6S. The solution obtained during the springtime cruise is consistent with the wintertime (September 1989) data set (Maamaatuaiahutapu et al., 1992): both show the large local recirculation of AAIW and the separation of NADW from the coast south of the thermocline front. However, noticeable changes in water mass mixing proportions can be detected between the winter of 1989 and the preceding spring. The seasonal change for the upper layers of TW and SASW is related to temporal and spatial fluctuations of the thermohaline front. The marked differences in SWT proportions between the two seasons occur at the same location for TW, SASW and AAIW; suggesting that the upper waters have a large impact on the AAIW movement. The deep waters undergo great spatial changes between the two cruises. The variation of the deep convergence position (revealed by the variation of spatial occupancy of the CDW and NADW) seems influenced by the movement of the thermocline front

EXAFS Debye-Waller factors issued from Car-Parrinello molecular dynamics: Application to the fit of oxaliplatin and derivatives

One of the main pitfalls in EXAFS fitting is correlation among parameters, which can lead to unreli- able fits. The use of theoretical Debye-Waller factors (DWs) is a promising way to reduce the number of fitted parameters. When working with molecular dynamics, it is not only possible to evaluate DWs from the statistical distributions issued from the trajectory but also to estimate the distribution an- harmonicity, and to compute simulated average EXAFS spectra that can be fitted as experimental ones, in order to assess the ability of EXAFS fitting to recover information on DWs, as well as other structural and spectroscopical parameters. The case studied is oxaliplatin, a third generation anticancer drug. The structural information and the simulated average spectra were derived from a Car-Parrinello molecular dynamics (CP-MD) trajectory of a compound closely related to oxaliplatin. We present the DWs issued from this simulation and their use, by taking their theoretical absolute values (no DW fitted) or their ratios (one DW fitted). In this second approach, the fit of oxaliplatin experimental spectra leads to DWs values very close to the theoretical ones. This shows that the CP-MD trajectory provides a good representation of the distance distributions for oxaliplatin. Trans- ferability of oxaliplatin DWs, for all relevant single and multiple scattering paths, to closely related compounds is proven for the case of bis(oxalato)platinum(II) and bis(ethylene diamine)platinum(II).Ministerio de Ciencia e Innovación CTQ2011-25932Junta de Andalucía P06-FQM-0148

The role of temperature in the magnetic irreversibility of type-I Pb superconductors

Evidence of how temperature takes part in the magnetic irreversibility in the intermediate state of a cylinder and various disks of pure type-I superconducting lead is presented. Isothermal measurements of first magnetization curves and magnetic hysteresis cycles are analyzed in a reduced representation that defines an equilibrium state for flux penetration in all the samples and reveals that flux expulsion depends on temperature in the disks but not in the cylinder. The magnetic field at which irreversibility sets in along the descending branch of the hysteresis cycle and the remnant magnetization at zero field are found to decrease with temperature in the disks. The contributions to irreversibility of the geometrical barrier and the energy minima associated to stress defects that act as pinning centers on normal-superconductor interfaces are discussed. The differences observed among the disks are ascribed to the diverse nature of the stress defects in each sample. The pinning barriers are suggested to decrease with the magnetic field to account for these results