Studier av cirrusskyer sett fra satellitt i relasjon til flytrafikk

Abstract On a sunny, cloudless day we often recognize condensation trails (contrails) behind jet aircrafts as narrow, white stripes. Contrails form as a mixture of warm, humid exhaust gases and colder, drier air exceeds water saturation in the plume. The exhaust particles may allow ice nucleation at lower supersaturations than those required under natural conditions. If the relative humidity with respect to ice is higher than 100%, then contrails may persist and evovlve into high-level cirrus clouds. The anthropogenic cirrus clouds have the potential for affecting climate via radiative forcing. Because of the rising global air traffic over the past decades and its associated contrails, there have been a substantial focus on estimates of radiative forcing from contrails compared to the total anthropogenic radiative forcing. In this study we use daily data rather than montly means in comparison to previous studies. The daily data consists of three different datasets taken for one week during summer. For predicting the environmental conditions required for contrail formation and peristence, we have used the Schmidt-Appleman criterion. Correlations will be spatially executed for different cirrus parameters before and after filtering out air traffic, globally and for four high-density air traffic areas. Results from the Schmidt-Appleman criterion indicate best conditions for contrail formation over East-Asia, and parts of Central-Europe and the North-Atlantic flight corridor. But the overall correlations shows a weak agreement between cirrus cloudiness and air traffic density, and even negative for some geographical locations. Best agreement is located over most of Asia, where the summer monsoon is responsible for the high cirrus occurence over this area. In addition, these contrails can persist and consequently affect the Earth’s radiative balance. Reanalysis from ECMWF (European Center for Medium-Range Weather Forecasts) shows that the satellite observations of cirrus can be partly explained by the weather conditions for the current week, and consequently affect the contrail formation. There are serveral uncertainties regarding the correlation results, like modeling of humidity from ECMWF. To improve the results, advection of aircraft induced cirrus should be taken into account

HVAD ER PSYKOLOGIENS GENSTANDSOMRÅDE?

Artiklens udgangspunkt er, at psykologiens gentandsområde, psyken, er irreduktibel. Forfatterne er enige om udgangspunktet, men i øvrigt tilhængere af vidt forskellige psykologiske retninger. De enkelte forfattere bestemmer hver især de afgørende irreduktible træk ved psyken. Til sidst i artiklen forsøges en sammenkædning af de enkelte synspunkter, der argumenteres mod eklekticisme og der specificeres en række grundspørgsmål til yderligere bestemmelse af psyken.The authors of this article argue that the subject of psychology, the psyche, is irreducible. While the authors agree on this point, they otherwise adhere to widely different psychological schools. Each proposes his or her definition of the irreducible characteristics of the psyche. Finally, there is an attempt to combine the different points of view, eclectisism is argued against, and several fundamental questions are specified for further determination of the psyche

A Tunable Two-impurity Kondo system in an atomic point contact

Two magnetic atoms, one attached to the tip of a Scanning Tunneling Microscope (STM) and one adsorbed on a metal surface, each constituting a Kondo system, have been proposed as one of the simplest conceivable systems potentially exhibiting quantum critical behaviour. We have succeeded in implementing this concept experimentally for cobalt dimers clamped between an STM tip and a gold surface. Control of the tip-sample distance with sub-picometer resolution allows us to tune the interaction between the two cobalt atoms with unprecedented precision. Electronic transport measurements on this two-impurity Kondo system reveal a rich physical scenario which is governed by a crossover from local Kondo screening to non-local singlet formation due to antiferromagnetic coupling as a function of separation of the cobalt atoms.Comment: 22 pages, 5 figure

Novel variation and <i>de novo </i>mutation rates in population-wide <i>de novo</i> assembled Danish trios

Building a population-specific catalogue of single nucleotide variants (SNVs), indels and structural variants (SVs) with frequencies, termed a national pan-genome, is critical for further advancing clinical and public health genetics in large cohorts. Here we report a Danish pan-genome obtained from sequencing 10 trios to high depth (50 × ). We report 536k novel SNVs and 283k novel short indels from mapping approaches and develop a population-wide de novo assembly approach to identify 132k novel indels larger than 10 nucleotides with low false discovery rates. We identify a higher proportion of indels and SVs than previous efforts showing the merits of high coverage and de novo assembly approaches. In addition, we use trio information to identify de novo mutations and use a probabilistic method to provide direct estimates of 1.27e−8 and 1.5e−9 per nucleotide per generation for SNVs and indels, respectively

Ice-Age Climate Adaptations Trap the Alpine Marmot in a State of Low Genetic Diversity.

Some species responded successfully to prehistoric changes in climate [1, 2], while others failed to adapt and became extinct [3]. The factors that determine successful climate adaptation remain poorly understood. We constructed a reference genome and studied physiological adaptations in the Alpine marmot (Marmota marmota), a large ground-dwelling squirrel exquisitely adapted to the "ice-age" climate of the Pleistocene steppe [4, 5]. Since the disappearance of this habitat, the rodent persists in large numbers in the high-altitude Alpine meadow [6, 7]. Genome and metabolome showed evidence of adaptation consistent with cold climate, affecting white adipose tissue. Conversely, however, we found that the Alpine marmot has levels of genetic variation that are among the lowest for mammals, such that deleterious mutations are less effectively purged. Our data rule out typical explanations for low diversity, such as high levels of consanguineous mating, or a very recent bottleneck. Instead, ancient demographic reconstruction revealed that genetic diversity was lost during the climate shifts of the Pleistocene and has not recovered, despite the current high population size. We attribute this slow recovery to the marmot's adaptive life history. The case of the Alpine marmot reveals a complicated relationship between climatic changes, genetic diversity, and conservation status. It shows that species of extremely low genetic diversity can be very successful and persist over thousands of years, but also that climate-adapted life history can trap a species in a persistent state of low genetic diversity.This work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001134), the UK Medical Research Council (FC001134), and the Wellcome Trust (FC001134). CB and AC are supported by the Agence Nationale de la Recherche (project ANR-13-JSV7-0005) and the Centre National de la Recherche Scientifique (CNRS), CB is supported by the Rhône-Alpes region (Grant 15.005146.01). LD is supported by Agence Nationale de la Recherche (project ANR-12-ADAP-0009). TIG is supported by a Leverhulme Early Career Fellowship (Grant ECF-2015-453) and a NERC grant (NE/N013832/1). JMG is supported by a Hertha Finberg Fellowship (FWF T703). LDR is supported by the Diabetes UK RD Lawrence Fellowship (16/0005382)