Operations and Performance of the PACS Instrument 3He Sorption Cooler on board of the Herschel Space Observatory

A 3He sorption cooler produced the operational temperature of 285mK for the bolometer arrays of the Photodetector Array Camera and Spectrometer (PACS) instrument of the Herschel Space Observatory. This cooler provided a stable hold time between 60 and 73h, depending on the operational conditions of the instrument. The respective hold time could be determined by a simple functional relation established early on in the mission and reliably applied by the scientific mission planning for the entire mission. After exhaustion of the liquid 3He due to the heat input by the detector arrays, the cooler was recycled for the next operational period following a well established automatic procedure. We give an overview of the cooler operations and performance over the entire mission and distinguishing in-between the start conditions for the cooler recycling and the two main modes of PACS photometer operations. As a spin-off, the cooler recycling temperature effects on the Herschel cryostat 4He bath were utilized as an alternative method to dedicated Direct Liquid Helium Content Measurements in determining the lifetime of the liquid Helium coolant.Comment: 34 pages, 13 figures, accepted in Experimental Astronom

The Herschel PACS photometer calibration - A time dependent flux calibration for the PACS chopped point-source photometry AOT mode

We present a flux calibration scheme for the PACS chopped point-source photometry observing mode based on the photometry of five stellar standard sources. This mode was used for science observations only early in the mission. Later, it was only used for pointing and flux calibration measurements. Its calibration turns this type of observation into fully validated data products in the Herschel Science Archive. Systematic differences in calibration with regard to the principal photometer observation mode, the scan map, are derived and amount to 5-6%. An empirical method to calibrate out an apparent response drift during the first 300 Operational Days is presented. The relative photometric calibration accuracy (repeatability) is as good as 1% in the blue and green band and up to 5% in the red band. Like for the scan map mode, inconsistencies among the stellar calibration models become visible and amount to 2% for the five standard stars used. The absolute calibration accuracy is therefore mainly limited by the model uncertainty, which is 5% for all three bands.Comment: 20 pages, 7 pages of appendix, 11 figures, accepted to appear in Experimental Astronomy, Special Issue for Herschel Calibrations based on the "Herschel Calibration Workshop: Only the Best Data Products for the Legacy Archive", held at ESAC, 25 - 27 March 2013, http://herschel.esac.esa.int/CalibrationWorkshop5.shtm

Termination of Ethereum's Smart Contracts

Ethereum is a decentralized blockchain technology equipped with so-called Smart Contracts. A contract is a program whose code is public, which can be triggered by any user, and whose actual execution is performed by miners participating in Ethereum. Miners execute the contract on the Ethereum Virtual Machine (EVM) and apply its effect by adding new blocks to the blockchain. A contract that takes too much time to be processed by the miners of the network may result into delays or a denial of service in the Ethereum system. To prevent this scenario, termination of Ethereum's Smart Contracts is ensured using a gas mechanism. Roughly, the EVM consumes gas to process each instruction of a contract and the gas provided to run a contract is limited. This technique could make termination of contracts easy to prove but the way the official definition of the EVM specifies gas usage makes the proof of this property non-trivial. EVM implementations and formal analysis techniques of EVM's Smart Contracts use termination of contracts as an assumption, so having a formal proof of termination of contracts is crucial. This paper presents a mechanized, formal, and general proof of termination of Smart Contracts based on a measure of EVM call stacks

La utilización de marfil de cachalote en el Calcolítico de Portugal

Scientific analysis were undertaken within a research project concerning ivory objects from the Chalcolithic to Early Bronze Age of the Iberian Peninsula. In several of the analyses of objects from Portuguese Estremadura, especially V-perforated buttons, we could detect for the first time the presence of sperm whale ivory. This highlights the advantage and necessity of scientific analysis of ivory. It also clearly demonstrates that not all ivory used was ivory from African or Asian elephants, but we also did find ivory from the extinct Elephas antiquus, the hippopotamus and in this case sperm-whale. Thus, already in the Chalcolithic the raw material provenience was highly diverse, which in the absence of scientific analysis might lead to an erroneous interpretation of prehistoric exchange networks. Different methods, including optical microscopy, measurement of hardness and specific gravity, Micro-Raman Spectroscopy, elemental analysis and Isotopic Ratio Mass Spectrometry have been applied. In this paper we present these methods and the results, and we discuss about the implications of these results for the reconstruction of prehistoric economy and life in this region. Finally, taking into account the natural conditions as well as prehistoric and historic data of whale hunting and scavenging of beached animals, we conclude that the most plausible explanation for the presence of sperm whale ivory in Chalcolithic Portugal is the use of the teeth obtained from stranded animals. This interpretation is possible because of the human populations using this ivory are those living close to the sea and exploiting – among others– marine resources.En el marco de un proyecto de investigación sobre objetos de marfil del Calcolítico al Bronce Antiguo en la Península Ibérica efectuamos análisis científicos. En varios de los objetos de la Estremadura portuguesa, en especial en los botones con perforación en V, detectamos por primera vez la presencia de marfil de cachalote. Así se demuestra claramente la ventaja y la necesidad de efectuar análisis científicos del marfil. No todo el marfil utilizado provenía de los elefantes africanos y asiáticos. Además encontramos marfil del desaparecido Elephas antiquus, de hipopótamo, y en este caso de cachalote. Así ya en el Calcolítico el origen de la materia prima era muy diverso, lo que en ausencia de análisis científicos puede conducir a una errónea interpretación de las redes prehistóricas de intercambio. Los métodos empleados fueron la microscopia óptica, la medición de la dureza y del peso específico, la espectroscopía Micro-Raman, el análisis elemental y la espectrometría isotópica de masas. En este trabajo presentamos estos métodos y los resultados. Además discutimos sus consecuencias para la reconstrucción de la economía y la vida de las sociedades prehistóricas de la región. Teniendo en cuenta las condiciones naturales y los datos prehistóricos e históricos sobre la caza de ballenas y el aprovechamiento de animales varados consideramos que la explicación más plausible de la presencia de marfil de cachalote en el caso del Calcolítico portugués es el uso de dientes de cachalotes varados. Cabe esta interpretación dado que las poblaciones que emplean este marfil son las que viven cerca del mar explotando, entre otros, los recursos marinos

Characterization of rhodolith beds in the northwestern Gulf of Mexico before and after the BP Deepwater Horizon oil spill

ABSTRACT: In the northwestern Gulf of Mexico beds of rhodoliths and unconsolidated rubble are associated with unique offshore deep bank habitats, the salt domes or diapirs that are peculiar to that part of the northern Gulf. In contrast to being mainly composed of crustose corallines (or foraminifera), rhodoliths in the NW Gulf of Mexico at depths of 40-85 m are instead dominated by red algal crust-forming members of Peyssonneliaceae and Rhizophyllidaceae.info:eu-repo/semantics/publishedVersio

Comparison of MRI properties between multimeric DOTAGA and DO3A gadolinium-dendron conjugates

The inherent lack of sensitivity of MRI needs the development of new Gd contrast agents in order to extend 20Hz,37%, the application of this technique to cellular imaging. For this purpose, two multimeric MR contrast agents obtained by peptidic coupling between an amido amine dendron and GdDOTAGA chelates (premetalation strategy, G1-4GdDOTAGA) or DO3A derivatives which then were postmetalated (G1-4GdDO-3A) have been prepared. By comparison to the monomers, an increase of longitudinal relaxivity has been observed for both structures. Especially for G1-4GdDO-3A, a marked increase is observed between 20 and 60 MHz. This structure differs from G1-4GdDOTAGA by an increased rigidity due to the aromatic linker between each chelate and the organic framework. This has the effect of limiting local rotational movements, which has a positive impact on relaxivity

The Hawaiian Algal Database: a laboratory LIMS and online resource for biodiversity data

<p>Abstract</p> <p>Background</p> <p>Organization and presentation of biodiversity data is greatly facilitated by databases that are specially designed to allow easy data entry and organized data display. Such databases also have the capacity to serve as Laboratory Information Management Systems (LIMS). The Hawaiian Algal Database was designed to showcase specimens collected from the Hawaiian Archipelago, enabling users around the world to compare their specimens with our photographs and DNA sequence data, and to provide lab personnel with an organizational tool for storing various biodiversity data types.</p> <p>Description</p> <p>We describe the Hawaiian Algal Database, a comprehensive and searchable database containing photographs and micrographs, geo-referenced collecting information, taxonomic checklists and standardized DNA sequence data. All data for individual samples are linked through unique accession numbers. Users can search online for sample information by accession number, numerous levels of taxonomy, or collection site. At the present time the database contains data representing over 2,000 samples of marine, freshwater and terrestrial algae from the Hawaiian Archipelago. These samples are primarily red algae, although other taxa are being added.</p> <p>Conclusion</p> <p>The Hawaiian Algal Database is a digital repository for Hawaiian algal samples and acts as a LIMS for the laboratory. Users can make use of the online search tool to view and download specimen photographs and micrographs, DNA sequences and relevant habitat data, including georeferenced collecting locations. It is publicly available at <url>http://algae.manoa.hawaii.edu</url>.</p

Ecology of the Invasive Red Alga Gracilaria salicornia (Rhodophyta) on O'ahu, Hawai'i

The red alga Gracilaria salicornia (C. Agardh) E. Y. Dawson was introduced intentionally to two reefs on O'ahu, Hawai'i, in the 1970s for experimental aquaculture for the agar industry. Some 30 yr later, this species has spread from the initial sites of introduction and is now competing with native marine flora and fauna. The goals of this study were to quantify various aspects of G. salicornia ecology in Hawai'i in an effort to develop control or eradication tools. Experimental plots were established to determine cover and biomass of G. salicornia per square meter and to determine the amount of time and person hours needed to remove G. salicornia from these plots. Substantial amounts of G. salicornia become dislodged from the reef during large wave events and periodically become deposited onto the beach in front of the Waikiki Aquarium. Algal beach wash biomass was quantified and positive relationships were established between swell height and the amount of algae that washed up onto the beach in this location. We then quantified the ability of G. salicornia vegetative fragments to regrow after desiccation to determine if algal biomass stranded on shore survives the tidal cycle until being washed back out on the reef at high tide. Gracilaria salicornia was remarkably resistant to temperature, salinity, and chemical treatments examined as possible in situ control options. Herbivore preference tests showed that a native Gracilaria species is consumed far more frequently than the alien congener. Finally, large-scale community volunteer efforts were organized to remove drifting G. salicornia fragments from the reef area in front of the Waikiki Aquarium. Over 20,000 kg of alien algal fragments were removed from this location in five 4-hr cleanup events. However, based on G. salicornia growth rates, ability to fragment, physical tolerance, and low herbivory, it is clear that a large-scale dedicated effort will be needed to control this invasive species on Waikiki's reefs

Nîmes – Le Viol du Plan

Date de l'opération : 1991 (SU) ; 1993 (SU) ; 1997 (SU) ; 1998 (SU) Inventeur(s) : Vidal Laurent (AFAN) ; Thomas S. ; Sauvage Laurent (AFAN) ; Hervé Marie-Laure (AFAN) ; Piskorz Michel (AFAN) Plan général des opérations extra muros de Nîmes (Fig. n°2 : Plan général des principales opérations rurales (1991-1998)). Quatre expertises ont été réalisées dans des parcelles situées au nord de l’autoroute A9, de part et d’autre du chemin de mas de Vignolles et à 1,8 km au sud de l’enceinte antique d..