The Mirror Alignment and Control System for CT5 of the H.E.S.S. experiment

The High Energy Stereoscopic System (H.E.S.S.) experiment is one of the largest observatories for gamma-ray astronomy. It consists of four telescopes with a reflecting dish diameter of 12m (CT1 to CT4) and a newer large telescope (CT5) with a reflecting dish diameter of 28m. On CT5 876 mirror facets are mounted, all of them equipped with a computerised system for their alignment. The design of the mirror alignment and control system and the performance of the hardware installed to the telescope are presented. Furthermore the achieved point spread function of the telescope over the full operational elevation range as well as the stability of the alignment over an extended period of time are shown

CSIC Abierto 3

10 páginas, 7 imágenes.La revista "CSIC Abierto" está dividida en 2 partes, una primera que informa sobre noticias varias de Digital.CSIC y da a conocer las investigaciones científicas depositadas en la plataforma así como las comunidades científica y bibliotecaria de los respectivos centros y una segunda parte que difunde recursos de interés y novedades en el contexto general del acceso abierto.Noticias de DIGITAL.CSIC: La investigación del CSIC en abierto: 1. Entrevista a Rafael Rodrigo, Presidente del CSIC. 2. Paisajes del terror y el acceso abierto: una mirada interdisciplinar.-- Novedades en DIGITAL.CSIC: 3. Actividades de Digital.CSIC en 2011. 4. Participación de Digital.CSIC en OpenAire. 5. Los handles de las noticias.-- Noticias y recursos de interés: 6. Colaboración entre la Red de Bibliotecas del CSIC y BioMed Central. 7. Herramientas de interés para conocer mejor cuestiones de copyright. 8. El impacto de las revistas en acceso abierto. 9. Google Books Ngram ViewerPeer reviewe

Imprinting Patterns of Neutral Atoms in an Optical Lattice using Magnetic Resonance Techniques

We prepare arbitrary patterns of neutral atoms in a one-dimensional (1D) optical lattice with single-site precision using microwave radiation in a magnetic field gradient. We give a detailed account of the current limitations and propose methods to overcome them. Our results have direct relevance for addressing of planes, strings or single atoms in higher dimensional optical lattices for quantum information processing or quantum simulations with standard methods in current experiments. Furthermore, our findings pave the way for arbitrary single qubit control with single site resolution.Comment: 9 pages, 7 figure

Tuning the critical magnetic field of the triplon Bose-Einstein condensation in Ba3−x_{3-x}Srx_xCr2_2O8_8

The structure and magnetic interactions of the triplon Bose-Einstein condensation candidates Ba$_3$Cr$_2$O$_8$ and Sr$_3$Cr$_2$O$_8$ have been studied thoroughly in the literature, but little is known about a possible triplon condensation in the corresponding solid solution Ba$_{3-x}$Sr$_x$Cr$_2$O$_8$. We have prepared various members of this solid solution and systematically examined their magnetic properties in high magnetic fields up to 60 T and at low temperatures down to 340 mK, by means of pulsed field and cantilever magnetometry. From these experiments for $x\in\{3,2.9,2.8,2.7,2.6,2.5\}$, we find that the critical fields of Ba$_{3-x}$Sr$_x$Cr$_2$O$_8$ decrease monotonically as a function of the Sr content $x$. This change is in good agreement with the earlier reported variation of the magnetic interactions in these compounds

The allspice [Pimenta dioica (L.) Merrill, Myrtaceae] in the Sierra Norte de Puebla (México)

13 páginas, 9 figuras, 3 tablas.[ES] Pimenta dioica es una miliacea neotropical de distribución mesoamericana y caribeña. En México vive hacia el este y sudeste. Sus frutos secos se utilizan como condimento, y se trata de un producto del mercado nacional mexicano que también se exporta a Alemania, Estados Unidos, Jamaica y Reino Unido. Aunque la mayoría de la cosecha proviene de la recolección de los frutos en árboles silvestres del bosque tropical, últimamente se tiende a cultivar esta especie en un proceso actual de domesticación. Se exponen datos sobre propagación, domesticación, cosecha, procesado, mercado e importancia socioeconómica de la pimienta de Jamaica en la Sierra Norte de Puebla (México), a partir de los datos de campo obtenidos principalmente en una comunidad indígena totonaca, en donde se usa como medicinal, en alimentación y en tecnología. Además se reseña una obra de carácter histórico sobre la pimienta de Gómez Ortega, que ofrece datos históricos, botánicos, de cultivo y de comercio de esta especie.[EN] Pimenta dioica, allspice, is a neotropical Myrtaceae distributed in Mesoamerica and the Caribbean region. Its área of distribution in México ranges along East and Southeast parts of the country. The main use of its dried fruits is as spice, being sold in Mexican nacional markets as well as exported to Germany, the United States, Jamaica and Great Britain. Most of the harvest comes from trees growing wild in tropical forests, although lately there is a trend to domesticate and cultivate the plant. This paper describes the propagation, domestication, harvesting, processing, marketing and socioeconomic importance of allspice in the Sierra Norte de Puebla (México). The fieldwork has been focused on Totonaca indigenous communities from this area. In these communities, allspice has medicinal use, and is used as a condiment for food; other technological and cultural uses have been also recorded. A historical monograph from Casimiro Gómez Ortega is reviewed. It includes information of the history, botany, cultivation and commerce of allspice.Este estudio se realizó dentro del período de disfrute de una Beca Intercampus E.AL./96 núm. 0384 de la Agencia Española de Cooperación Internacional (AECI).Peer reviewe

Market Risk: Exponential Weightinh in the Value-at-Risk Calculation

When measuring market risk, credit institutions and Alternative Investment Fund Managers may deviate from equally weighting historical data in their Value-at-Risk calculation and instead use an exponential time series weighting. The use of expo-nential weighting in the Value-at-Risk calculation is very popular because it takes into account changes in market volatility (immediately) and can therefore quickly adapt to VaR. In less volatile market phases, this leads to a reduction in VaR and thus to lower own funds requirements for credit institutions. However, in the ex-ponential weighting a high volatility in the past is quickly forgotten and the VaR can be underestimated when using exponential weighting and the VaR may be un-derestimated. To prevent this, credit institutions or Alternative Investment Fund Managers are not completely free to choose a weighting (decay) factor. This article describes the legal requirements and deals with the calculation of the permissible weighting factor. As an example we use the exchange rate between Euro and Polish zloty to estimate the Value-at-Risk. We show the calculation of the weighting factor with two different approaches. This article also discusses exceptions to the general legal requirements

Die Handelskosten von Sachsen

Die regionale Struktur und das Volumen der sächsischen Exporte und Importe erklären sich nicht nur durch die relativen Kostenunterschiede zwischen Sachsen und den Handelspartnern; mitentscheidend sind auch die Handelskosten für Exporte und Importe der sächsischen Wirtschaft. Unter Handelskosten werden Transportkosten, Kosten des Grenzübergangs der Ware und Distributionskosten, die im Empfängerland entstehen, verstanden. Jüngste empirische Arbeiten zu Kosten im internationalen Handel zeigen ein überraschendes Ergebnis: Für die OECD-Staaten entstehen im Durchschnitt Handelskosten, die einem Aufschlag von über 170 % entsprechen. Handelskosten können als Aufschlag, d. h. als ein Wertzoll aufgefasst werden. Unser Beitrag verwendet einen neuen Handelskostenindex, um die Handelskosten in Form eines Zolläquivalents für die sächsische Wirtschaft zu ermitteln. Im Jahr 1992 lag der durchschnittliche gewichtete Aufschlag für mit Sachsen gehandelte Waren bei 1,70. Im Jahr 2008 nahm dieser Aufschlag der Handelskosten in etwa den Wert eins an. Damit muss zum ursprünglichen Warenwert noch einmal der gleiche Wert für die Kosten des Handels aufgebracht werden.Außenwirtschaft; Transaktionskosten; Transportkosten; Informationskosten; Außenhandelsbeschränkung; Vergleich; Sachsen; OECD-Staaten

Review on Experimental and Theoretical Investigations of Ultra-Short Pulsed Laser Ablation of Metals with Burst Pulses

Laser processing with ultra-short double pulses has gained attraction since the beginning of the 2000s. In the last decade, pulse bursts consisting of multiple pulses with a delay of several 10 ns and less found their way into the area of micromachining of metals, opening up completely new process regimes and allowing an increase in the structuring rates and surface quality of machined samples. Several physical effects such as shielding or re-deposition of material have led to a new understanding of the related machining strategies and processing regimes. Results of both experimental and numerical investigations are placed into context for different time scales during laser processing. This review is dedicated to the fundamental physical phenomena taking place during burst processing and their respective effects on machining results of metals in the ultra-short pulse regime for delays ranging from several 100 fs to several microseconds. Furthermore, technical applications based on these effects are reviewed