Probing halo nucleus structure through intermediate energy elastic scattering

This work addresses the question of precisely what features of few body models of halo nuclei are probed by elastic scattering on protons at high centre-of-mass energies. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of $^{11}$Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering crosssections can not, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead.Comment: 8 pages REVTeX, 1 eps figure, accepted for publication in Phys. Rev.

Buyer-seller conflict and cooperation in marketing channels: port wine distribution

The main purpose of this study is to research buyer-seller conflict and cooperation in distribution channels. Based on a multidimensional case study, eight research hypotheses were formulated. Some quantitative research was conducted, based on a questionnaire sent to 101 port wine producers and distribution companies (61 answered properly – 31 producers and 29 distributors – which gave the authors a 60% rate of response, considered to be very good for these types of studies; those 101 port wine producers and distributors initially chosen were the most important in Europe, considering the volume of production and sales, and constituting, for that reason, a convenience sample). A binary probit model was developed to analyze the data. The results of the study demonstrate that when conflict is ongoing and intense it prevents the development of cooperative relationships. A trustworthy company is more likely to solve conflicts. When trust and adaptation capabilities increase, so does potential cooperation. The results also show that the presence of a foreign sales representative in the team does not exert a negative influence on cooperation. Finally, cooperation can be considered as an important means of developing skills and resources, which can then be applied to existing transaction relationships

The macroeconomic effects of international uncertainty shocks

We propose a large-scale Bayesian VAR model with factor stochastic volatility to investigate the macroeconomic consequences of international uncertainty shocks on the G7 countries. The factor structure enables us to identify an international uncertainty shock by assuming that it is the factor most correlated with forecast errors related to equity markets and permits fast sampling of the model. Our findings suggest that the estimated uncertainty factor is strongly related to global equity price volatility, closely tracking other prominent measures commonly adopted to assess global uncertainty. The dynamic responses of a set of macroeconomic and financial variables show that an international uncertainty shock exerts a powerful effect on all economies and variables under consideration

Closed-cycle, low-vibration 4 K cryostat for ion traps and other applications

In-vacuo cryogenic environments are ideal for applications requiring both low temperatures and extremely low particle densities. This enables reaching long storage and coherence times for example in ion traps, essential requirements for experiments with highly charged ions, quantum computation, and optical clocks. We have developed a novel cryostat continuously refrigerated with a pulse-tube cryocooler and providing the lowest vibration level reported for such a closed-cycle system with 1 W cooling power for a <5 K experiment. A decoupling system suppresses vibrations from the cryocooler by three orders of magnitude down to a level of 10 nm peak amplitudes in the horizontal plane. Heat loads of about 40 W (at 45 K) and 1 W (at 4 K) are transferred from an experimental chamber, mounted on an optical table, to the cryocooler through a vacuum-insulated massive 120 kg inertial copper pendulum. The 1.4 m long pendulum allows installation of the cryocooler in a separate, acoustically isolated machine room. In the laser laboratory, we measured the residual vibrations using an interferometric setup. The positioning of the 4 K elements is reproduced to better than a few micrometer after a full thermal cycle to room temperature. Extreme high vacuum on the $10^{-15}$ mbar level is achieved. In collaboration with the Max-Planck-Intitut f\"ur Kernphysik (MPIK), such a setup is now in operation at the Physikalisch-Technische Bundesanstalt (PTB) for a next-generation optical clock experiment using highly charged ions

Continuous spectra in high-harmonic generation driven by multicycle laser pulses

We present observations of the emission of XUV continua in the 20-37 eV region by high harmonic generation (HHG) with $4$-$7\ \mathrm{fs}$ pulses focused onto a Kr gas jet. The underlying mechanism relies on coherent control of the relative delays and phases between individually generated attosecond pulse, achievable by adjusting the chirp of the driving pulses and the interaction geometry. Under adequate negative chirp and phase matching conditions, the resulting interpulse interference yields a continuum XUV spectrum, which is due to both microscopic and macroscopic (propagation) contributions. This technique opens the route for modifying the phase of individual attosecond pulses and for the coherent synthesis of XUV continua from multicycle driving laser pulses without the need of an isolated attosecond burst.Comment: 14 pages, 5 figures. Submitted to Physical Review

Assessing the use of discrete, full-waveform LiDAR and TLS to classify Mediterranean forest species composition

Revista oficial de la Asociación Española de Teledetección[EN] LiDAR technology –airborne and terrestrial- is becoming more relevant in the development of forest inventories, which are crucial to better understand and manage forest ecosystems. In this study, we assessed a classification of species composition in a Mediterranean forest following the C4.5 decision tree. Different data sets from airborne laser scanner full-waveform (ALSFW), discrete (ALSD) and terrestrial laser scanner (TLS) were combined as input data for the classification. Species composition were divided into five classes: pure Quercus ilex plots (QUI); pure Pinus halepensis dense regenerated (HALr); pure P. halepensis (HAL); pure P. pinaster (PIN); and mixed P. pinaster and Q. suber (mPIN). Furthermore, the class HAL was subdivided in low and dense understory vegetation cover. As a result, combination of ALSFW and TLS reached 85.2% of overall accuracy classifying classes HAL, PIN and mPIN. Combining ALSFW and ALSD, the overall accuracy was 77.0% to discriminate among the five classes. Finally, classification of understory vegetation cover using ALSFW reached an overall accuracy of 90.9%. In general, combination of ALSFW and TLS improved the overall accuracy of classifying among HAL, PIN and mPIN by 7.4% compared to the use of the data sets separately, and by 33.3% with respect to the use of ALSD only. ALSFW metrics, in particular those specifically designed for detection of understory vegetation, increased the overall accuracy 9.1% with respect to ALSD metrics. These analyses show that classification in forest ecosystems with presence of understory vegetation and intermediate canopy strata is improved when ALSFW and/or TLS are used instead of ALSD.[ES] La tecnología LiDAR, tanto en sus versiones aerotransportada como terrestre, ha adquirido relevancia en los últimos años en la realización de inventarios forestales que permiten entender y adecuar la gestión de los ecosistemas forestales. En este estudio, se evaluó la clasificación por composición de especies en un bosque mediterráneo mediante el árbol de decisión C4.5. Para ello, se emplearon diferentes conjuntos de datos derivados de LiDAR discreto (ALSD ), LiDAR de retorno de onda completa (full-waveform, ALSFW) y láser escáner terrestre (TLS) como datos de entrada de la clasificación. La composición de especies se dividió en cinco clases: parcelas puras de Quercus ilex (QUI); puras de Pinus halepensis regenerado (HALr); puras de P. halepensis (HAL); puras de P. pinaster (PIN); y mixta de P. pinaster y Q. suber (mPIN). Además, se realizó una subdivisión de la clase HAL en cobertura de sotobosque escasa y densa. Como resultado se obtuvo una fiabilidad del 85,2% en la clasificación de las clases HAL, PIN y mPIN combinando ALSFW y TLS. En la clasificación de las cinco composiciones de especies, la fiabilidad alcanzada empleando ALSFW y ALSD fue del 77,0%. Finalmente, en la clasificación de las subclases de cobertura de sotobosque se logró un 90,9% de fiabilidad con ALSFW. En general, la combinación de ALSFW y TLS mejoró los resultados en un 7,4% en la clasificación de las clases HAL, PIN y mPIN en comparación con el uso de los datos de los sensores por separado, y en un 33,3% con respecto al uso de ALSD. Las métricas ALSFW, en particular aquellas diseñadas especialmente para la detección del sotobosque, mejoraron la precisión en un 9,1% con respecto a las métricas derivadas de ALSD. Estos análisis muestran que el uso del ALSFW y TLS mejora la clasificación de los ecosistemas forestales con presencia de sotobosque y diferentes especies arbóreas en los estratos intermedios con respecto al ALSD.This research has been funded by the Spanish Ministerio de Economia y Competitividad and FEDER, in the framework of the project CGL2016-80705-R.Torralba, J.; Crespo-Peremarch, P.; Ruiz, LA. (2018). Evaluación del uso de LiDAR discreto, full-waveform y TLS en la clasificación por composición de especies en bosques mediterráneos. Revista de Teledetección. (52):27-40. https://doi.org/10.4995/raet.2018.11106SWORD274052Åkerblom, M., Raumonen, P., Mäkipää, R., Kaasalainen, M. 2017. Automatic tree species recognition with quantitative structure models. 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Expanded Very Large Array Observations of the Nebula Around G79.29+0.46

We have observed the radio nebula surrounding the Galactic luminous blue variable candidate G79.29+0.46 with the Expanded Very Large Array (EVLA) at 6 cm. These new radio observations allow a morphological comparison between the radio emission, which traces the ionized gas component, and the mid-IR emission, a tracer of the dust component. The InfraRed Array Camera (8 μm) and the Multiband Imaging Photometer for Spitzer (24 μm and 70 μm) images have been reprocessed and compared with the EVLA map. We confirm the presence of a second shell at 24 μm and also provide evidence for its detection at 70 μm. The differences between the spatial morphology of the radio and mid-IR maps indicate the existence of two dust populations, the cooler one emitting mostly at longer wavelengths. Analysis of the two dusty, nested shells have provided us with an estimate of the characteristic timescales for shell ejection, providing important constraints for stellar evolutionary models. Finer details of the ionized gas distribution can be appreciated thanks to the improved quality of the new 6 cm image, most notably the highly structured texture of the nebula. Evidence of interaction between the nebula and the surrounding interstellar medium can be seen in the radio map, including brighter features that delineate regions where the shell structure is locally modified. In particular, the brighter filaments in the southwest region appear to frame the shocked southwestern clump reported from CO observations