154 research outputs found
Assessing Nature? The Genesis of the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES)
International audienceBased on an anlysis of the creation of an IPBES, our contribution addresses the progressive stabilization of an institutional design for assessing Nature. As regards the implementation of new forms of environmental governance, social science literature has zidely promoted norms of transparency, openness and participation. But so far, few researchers have focused on the way this disclosure model now concretely weighs down on real institutions and institutionalization processes. Little attention has been paid to the way this requirement can combine with other requirements or older models of action. In the case of IPBES, our goal is to question how the requirements of participation and transparency are put into practice. We will highlight the role of UNEP (United Nations Environment Program) in the institutionalization process of IPBES and see how the disclosure model is combined with other requirements which simultaneously involve the re-creation of "enclosure" (i.e. the need for academic sound science, or the usual way in which things are done at UNEP, i.e. bureaucratic practices). OUr work is based on an empirical study including documentation analysis and interviews
Technical note:On the reliability of laboratory beta-source calibration for luminescence dating
The dose rate of the 90Sr / 90Y beta source used in most
luminescence readers is a laboratory key parameter. There is a
well-established body of knowledge about parameters controlling accuracy and
precision of the calibration value but some hard-to-explain inconsistencies
still exist. Here, we have investigated the impact of grain size, aliquot
size and irradiation geometry on the resulting calibration value through
experiments and simulations. The resulting data indicate that the dose rate
of an individual beta source results from the interplay of a number of
parameters, most of which are well established by previous studies. Our
study provides evidence for the impact of aliquot size on the absorbed dose
in particular for grain sizes of 50–200 µm. For this grain-size
fraction, the absorbed dose is enhanced by ∼ 10 %–20 % as
aliquot size decreases due to the radial increase of dose rate towards
the centre of the aliquot. The enhancement is most variable for 50–100 µm
grains mounted as aliquots of < 8 mm size. The enhancement is
reversed when large grains are mounted as small aliquots due to the edge
effect by which the dose induced by backscattered electrons is reduced.
While the build-up of charge dictates the increase of absorbed dose with the
increase of grain size, this principle becomes more variable with changing
irradiation geometry. We conclude that future calibration samples should
consist of subsamples composed of small, medium, large and very large quartz
grains, each obtaining several gamma doses. The calibration value measured
with small, medium and large aliquots is then obtained from the inverse
slope of the fitted line, not from a single data point. In this way, all
possible irradiation geometries of an individual beta source are covered,
and the precision of the calibration is improved.</p
Weak Field Magnetoresistance in Quasi-One-Dimensional Systems
Theoretical studies are presented on weak localization effects and
magnetoresistance in quasi-one-dimensional systems with open Fermi surfaces.
Based on the Wigner representation, the magnetoresistance in the region of weak
field has been studied for five possible configurations of current and field
with respect to the one-dimensional axis. It has been indicated that the
anisotropy and its temperature dependences of the magnetoresistance will give
information on the degree of one-dimensionality and the phase relaxation time.Comment: pages 11, LaTeX, 5 figures, uses jpsj.sty. To be published in J.
Phys. Soc. Jpn. (Vol.67(1998) No.4); Added some references and a Note at Feb.
13 199
Metal-insulator transitions in anisotropic 2d systems
Several phenomena related to the critical behaviour of non-interacting
electrons in a disordered 2d tight-binding system with a magnetic field are
studied. Localization lengths, critical exponents and density of states are
computed using transfer matrix techniques. Scaling functions of isotropic
systems are recovered once the dimension of the system in each direction is
chosen proportional to the localization length. It is also found that the
critical point is independent of the propagation direction, and that the
critical exponents for the localization length for both propagating directions
are equal to that of the isotropic system (approximately 7/3). We also
calculate the critical value of the scaling function for both the isotropic and
the anisotropic system. It is found that the isotropic value equals the
geometric mean of the two anisotropic values. Detailed numerical studies of the
density of states for the isotropic system reveals that for an appreciable
amount of disorder the critical energy is off the band center.Comment: 6 pages RevTeX, 6 figures included, submitted to Physical Review
Dimensional Crossover of Weak Localization in a Magnetic Field
We study the dimensional crossover of weak localization in strongly
anisotropic systems. This crossover from three-dimensional behavior to an
effective lower dimensional system is triggered by increasing temperature if
the phase coherence length gets shorter than the lattice spacing . A similar
effect occurs in a magnetic field if the magnetic length becomes shorter
than , where \D_{||}/D_\perp is the ratio of the
diffusion coefficients parallel and perpendicular to the planes or chains.
depends on the direction of the magnetic field, e.g. or
1/2 for a magnetic field parallel or perpendicular to the planes in a quasi
two-dimensional system. We show that even in the limit of large magnetic field,
weak localization is not fully suppressed in a lattice system. Experimental
implications are discussed in detail.Comment: RevTeX, 11 pages, 4 figures; three references added and discusse
Grand Challenges (and Great Opportunities) in Sedimentology, Stratigraphy, and Diagenesis Research
No abstract available
Are publicly available internet resources enabling women to make informed fertility preservation decisions before starting cancer treatment: an environmental scan?
Background To identify publicly available internet resources and assess their likelihood to support women making informed decisions about, and between, fertility preservation procedures before starting their cancer treatment. Methods A survey of publically available internet resources utilising an environmental scan method. Inclusion criteria were applied to hits from searches of three data sources (November 2015; repeated June 2017): Google (Chrome) for patient resources; repositories for clinical guidelines and projects; distribution email lists to contact patient decision aid experts. The Data Extraction Sheet applied to eligible resources elicited: resource characteristics; informed and shared decision making components; engagement health services. Results Four thousand eight hundred fifty one records were identified; 24 patient resources and 0 clinical guidelines met scan inclusion criteria. Most resources aimed to inform women with cancer about fertility preservation procedures and infertility treatment options, but not decision making between options. There was a lack of consistency about how health conditions, decision problems and treatment options were described, and resources were difficult to understand. Conclusions Unless developed as part of a patient decision aid project, resources did not include components to support proactively women’s fertility preservation decisions. Current guidelines help people deliver information relevant to treatment options within a single disease pathway; we identified five additional components for patient decision aid checklists to support more effectively people’s treatment decision making across health pathways, linking current with future health problems
Sea level and climate changes during OIS 5e in the Western Mediterranean
Palaeontological, geomorphological and sedimentological data supported by isotopic dating on Oxygen
Isotopic Stage (OIS) 5e deposits from the Spanish Mediterranean coast, are interpreted with the aim of
reconstructing climatic instability in the Northern Hemisphere. Data point to marked climatic instability
during the Last Interglacial (OIS 5e), with a change in meteorological conditions and, consequently, in the
sedimentary environment. The oolitic facies generated during the first part of OIS 5e (ca. 135 kyr) shift into
reddish conglomeratic facies during the second part (ca. 117 kyr). Sea surface Temperature (SST) and salinity
are interpreted mainly on the basis of warm Senegalese fauna, which show chronological and spatial
differential distribution throughout the Western Mediterranean. Present hydrological and meteorological
conditions are used also as modern analogues to reconstruct climatic variability throughout the Last
Interglacial, and this variability is interpreted within the wider framework of the North Atlantic record. All
the available data indicate an increase in storminess induced by an increase in the influence of northwesterlies,
a slight drop of SST in the northern Western Mediterranean, and an important change in
meteorological conditions at the end of OIS 5e (117 kyr). These changes correlate well with the decrease in
summer insolation and with the climatic instability recorded in North Atlantic high latitudes
Evaluation of bearing, gears and gearboxes performance with different wind turbine gear oils
Mid-Holocene pulse of thinning in the Weddell Sea sector of the West Antarctic ice sheet
Establishing the trajectory of thinning of the West Antarctic ice sheet (WAIS) since the last glacial maximum (LGM) is important for addressing questions concerning ice sheet (in)stability and changes in global sea level. Here we present detailed geomorphological and cosmogenic nuclide data from the southern Ellsworth Mountains in the heart of the Weddell Sea embayment that suggest the ice sheet, nourished by increased snowfall until the early Holocene, was close to its LGM thickness at 10 ka. A pulse of rapid thinning caused the ice elevation to fall ~400 m to the present level at 6.5–3.5 ka, and could have contributed 1.4–2 m to global sea-level rise. These results imply that the Weddell Sea sector of the WAIS contributed little to late-glacial pulses in sea-level rise but was involved in mid-Holocene rises. The stepped decline is argued to reflect marine downdraw triggered by grounding line retreat into Hercules Inlet
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