1,721,117 research outputs found
X-ray diffraction as a function of temperature for Fo92-Fa8: implications for the hermean surface.
No full textIt is well known that the surface of Mercury shows
temperature variations extremely large at specific
locations [1]. Such a range can cause strong crystal
structure changes and, as a consequence, the detected
spectral signature could be significantly affected.
Here we investigated the low-high temperature
behaviour of one of the olivine, which has been
recently considered as a possible constituent of the
Mercury surface [2]. Aim of the work is to determine
which expansion the olivine undergoes within a
temperature range typical of the Mercury surface in
order to verify which could be the effect of thermal
expansion on a spectra
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Martian analogues emissivity spectra from the Berlin Emissivity Database (BED) in the [3-50] µm spectral region
No full textSpectral Library: The Berlin Emissivity
Database (BED) is a spectral library containing the
emissivity measurements of several planetary
analogues. It contains currently entries for
plagioclase and potassium feldspars, low Ca and
high Ca pyroxenes, olivines, elemental sulphur,
common martian analogues (JSC Mars-1, Salten
Skov, palagonites, montmorillonite, hematite,
goethite) and a lunar highland soil sample measured
in the wavelength range from 3 to 50 µm as a
function of particle size. For each sample, the
spectra of four well defined particle size separates
(<25 µm , 25-63 µm, 63-125 µm, 125-250 µm) are
measured with a 4 cm-1 spectral resolution. These
size separates have been selected as typical
representations for most of the planetary surfaces
[1].Laboratory set-up: The instrumentation is
located in the Planetary Emissivity Laboratory
(PEL) at the Institute for Planetary Research (PF) of
the German Aerospace Center (DLR) in Berlin,
Germany. It consists of a spectrometer attached to
an external emissivity device. The Bruker VERTEX
80v spectrometer, has a very high spectral resolution
(better then 0.2 cm-1), and a resolving power of
better than 300,000:1, and can be operated under
vacuum conditions. To cover the entire 1 to 50 µm
spectral range, two detectors, a liquid nitrogen
cooled MTC and a room temperature DTGS and
two beamsplitter, a KBr and a Multilayer are used to
measure the same target.
The emissivity device is composed of the sample
chamber, a double-walled box with three apertures:
a 15 cm squared door used to insert the cup in the
box, a 5 cm rounded opening through which the
beam is directed to the spectrometer and a 5 cm
opening facing the attached blackbody unit. A
heater is placed in the chamber and is used to heat
the cup with samples from the bottom. The thermal
radiation emitted normal to the surface by the
sample or the blackbody is collected by an Aucoated
parabolic off-axis mirror and reflected to the
entrance port of the spectrometer. Figure 1 shows
the emissivity device attached to the spectrometer
external port: the sample chamber is opened to show
the parabolic mirror mounted on a mechanical arm
and oriented toward the reference blackbody, the
sample heater and the purging system.
A pump circulates water at a constant
temperature in the volume between the inner and
outer walls of the chamber. The surfaces of the box
are painted with black high emissivity paint. The
chamber is purged with dry air to remove
particulates, water vapour and CO2. Further details
can be found in [2, 3].
Emissivity spectra: In Figure 2 an example of
quartz measurements for two extreme grain sizes is
shown, together with analogue measurements
extracted from the ASU and ASTER spectral
libraries. Complementary to the existing datasets
(ASU and ASTER), the BED library sensibly extend
both the investigated spectral range and the grain
size ranges. The enormous difference between the
spectra of the small and large fractions witness the
need for such a complete dataset for a correct
interpretation of remote sensing data.
Martian analogues: The emission spectra of
standard martian analogue materials like the JSC
Mars-1 (a palagonitic tephra from Hawaii, USA),
the Salten Skov (a Fe-oxide precipitate from the
Midjutland region of Denmark), montmorillonite,
hematite, goethite and some palagonites from
Hawaii, USA, are shown and discussed in this
paper.
References: [1] Helbert, J. et al. (2007), ASR 40,
DOI:10.1016/j.asr.2006.11.004. [2] Maturilli, A. et al.
(2006), PSS 54. [3] Maturilli, A. et al. (2007), in press
on PSS.</p
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Thermal Infrared spectroscopy as a function of temperature for Mercury rock-forming minerals: application to remote sensing.
No full text- …
