131,334 research outputs found
Dr. J. C. Bluntschli
No full textNach d. Natur gez. v. Hans Notz ; Bei Fr. Hohe auf Stein gez. v. AtzingerZuschreibung an Johannes Notz ungesicher
Dr. J. C. Bluntschli
No full textNach d. Natur gez. v. Hans Notz ; Bei Fr. Hohe auf Stein gez. v. Atzinge
[Porträt des J. J. Steffan]
No full textPorträt des J. J. SteffanNach d. Nat. gez. v. J. Notz ; G. Balder lith.Faksimilierter Autograph unterhalb der Grafik auf der UnterlageDie Person kann nicht näher individualisiert werde
A 1-D modelling study of Arctic sea-ice salinity
No full textWe use a 1-D model to study how salinity evolves in Arctic sea ice. To do so,
we first explore how sea-ice surface melt and flooding can be incorporated
into the 1-D thermodynamic Semi-Adaptive
Multi-phase Sea-Ice Model (SAMSIM) presented by
Griewank and Notz (2013). We introduce flooding and a flushing parametrization
which treats sea ice as a hydraulic network of horizontal and vertical
fluxes. Forcing SAMSIM with 36 years of ERA-interim atmospheric reanalysis
data, we obtain a modelled Arctic sea-ice salinity that agrees well with
ice-core measurements. The simulations thus allow us to identify the main
drivers of the observed mean salinity profile in Arctic sea ice. Our results
show a 1.5–4 g kg−1 decrease of bulk salinity via gravity drainage after ice
growth has ceased and before flushing sets in, which hinders approximating
bulk salinity from ice thickness beyond the first growth season. In our
simulations, salinity interannual variability of first-year ice is mostly
restricted to the top 20 cm. We find that ice thickness, thermal resistivity,
freshwater column, and stored energy change by less than 5% on average when
the full salinity parametrization is replaced with a prescribed salinity
profile
Efficient block designs for comparing dual with single treatments.
No full textExperiments in blocks having two treatment factors are considered in which a particular treatment must be excluded. The work is motivated by medical trials of two drugs in which a double placebo cannot be administered on ethical grounds. The contrasts of interest compare the effects of having both treatment factor at non-zero labelled levels with the effects of having only one treatment factor at a non-zero labelled level. For nx2 experiments, a class of designs containing highly efficient members is identified and a lower bound on the efficiencies of designs in this class is derived. Tables of efficient designs are provided
When Will Arctic Sea Ice Be Gone?
No full textThe Arctic sea ice is the ice that is floating on the Arctic Ocean. In recent decades, this pack ice has been disappearing very rapidly. So the question arises when the Arctic sea ice will be completely gone. DIRK NOTZ has examined this using the Arctic summer sea ice in September as example. As he explains in this video, his research group combined satellite observations with model simulations and found a clear linear correlation between the loss of Arctic sea ice and carbon dioxide emissions. For each ton of CO2 we emit, we make about three square meters of Arctic sea ice disappear. From this linear relationship the researchers could extrapolate the amount of carbon dioxide that can still be emitted before the Arctic sea ice is completely gone in summers. For the first time, these findings present very intuitive numbers that make clear the impact every individual has on the global warming
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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