| 1. |
- Breznau, Nate, et al.
(author)
-
Observing many researchers using the same data and hypothesis reveals a hidden universe of uncertainty
- 2022
-
In: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:44
-
Journal article (peer-reviewed)abstract
- This study explores how researchers analytical choices affect the reliability of scientific findings. Most discussions of reliability problems in science focus on systematic biases. We broaden the lens to emphasize the idiosyncrasy of conscious and unconscious decisions that researchers make during data analysis. We coordinated 161 researchers in 73 research teams and observed their research decisions as they used the same data to independently test the same prominent social science hypothesis: that greater immigration reduces support for social policies among the public. In this typical case of social science research, research teams reported both widely diverging numerical findings and substantive conclusions despite identical start conditions. Researchers expertise, prior beliefs, and expectations barely predict the wide variation in research outcomes. More than 95% of the total variance in numerical results remains unexplained even after qualitative coding of all identifiable decisions in each teams workflow. This reveals a universe of uncertainty that remains hidden when considering a single study in isolation. The idiosyncratic nature of how researchers results and conclusions varied is a previously underappreciated explanation for why many scientific hypotheses remain contested. These results call for greater epistemic humility and clarity in reporting scientific findings.
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| 2. |
- Unsalan, Ozan, et al.
(author)
-
The Sariçiçek howardite fall in Turkey : Source crater of HED meteorites on Vesta and impact risk of Vestoids
- 2019
-
In: Meteoritics and Planetary Science. - Hoboken : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 54:5, s. 953-1008
-
Journal article (peer-reviewed)abstract
- The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic‐ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid was launched by an impact 22 ± 2 Ma ago to Earth (as did one‐third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 ± 2.5 Ma and 4553 ± 8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U‐Pb age of 4525 ± 17 Ma, K‐Ar age of ~3.9 Ga, and the U,Th‐He ages of 1.8 ± 0.7 and 2.6 ± 0.3 Ga are interpreted to represent thermal metamorphic and impact‐related resetting ages, respectively. Petrographic; geochemical; and O‐, Cr‐, and Ti‐isotopic studies confirm that Sariçiçek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Sariçiçek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 ± 0.8 km s−1 from NW; fragmentations at 37, 33, 31, and 27 km altitude; and provide a pre‐atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Sariçiçek with the Vesta asteroid family (V‐class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a ~1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids ≤4 m in size to account for the influx of meteorites from this HED clan. The 16.7 km diameter Antionia impact crater on Vesta was formed on terrain of the same age as given by the 4He retention age of Sariçiçek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed ~22 Ma ago.
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| 3. |
- Arndt, D. S., et al.
(author)
-
State of the Climate in 2016
- 2017
-
In: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 98:8, s. S1-S280
-
Journal article (peer-reviewed)abstract
- In 2016, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued to increase and reach new record highs. The 3.5 +/- 0.1 ppm rise in global annual mean carbon dioxide from 2015 to 2016 was the largest annual increase observed in the 58-year measurement record. The annual global average carbon dioxide concentration at Earth's surface surpassed 400 ppm (402.9 +/- 0.1 ppm) for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800000 years. One of the strongest El Nino events since at least 1950 dissipated in spring, and a weak La Nina evolved later in the year. Owing at least in part to the combination of El Nino conditions early in the year and a long-term upward trend, Earth's surface observed record warmth for a third consecutive year, albeit by a much slimmer margin than by which that record was set in 2015. Above Earth's surface, the annual lower troposphere temperature was record high according to all datasets analyzed, while the lower stratospheric temperature was record low according to most of the in situ and satellite datasets. Several countries, including Mexico and India, reported record high annual temperatures while many others observed near-record highs. A week-long heat wave at the end of April over the northern and eastern Indian peninsula, with temperatures surpassing 44 degrees C, contributed to a water crisis for 330 million people and to 300 fatalities. In the Arctic the 2016 land surface temperature was 2.0 degrees C above the 1981-2010 average, breaking the previous record of 2007, 2011, and 2015 by 0.8 degrees C, representing a 3.5 degrees C increase since the record began in 1900. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 24 March, the sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, tying with 2015 at 7.2% below the 1981-2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the second lowest value on record, 33% lower than the 1981-2010 average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt. The mass of the Greenland Ice Sheet, which has the capacity to contribute similar to 7 m to sea level rise, reached a record low value. The onset of its surface melt was the second earliest, after 2012, in the 37-year satellite record. Sea surface temperature was record high at the global scale, surpassing the previous record of 2015 by about 0.01 degrees C. The global sea surface temperature trend for the 21st century-to-date of +0.162 degrees C decade(-1) is much higher than the longer term 1950-2016 trend of +0.100 degrees C decade(-1). Global annual mean sea level also reached a new record high, marking the sixth consecutive year of increase. Global annual ocean heat content saw a slight drop compared to the record high in 2015. Alpine glacier retreat continued around the globe, and preliminary data indicate that 2016 is the 37th consecutive year of negative annual mass balance. Across the Northern Hemisphere, snow cover for each month from February to June was among its four least extensive in the 47-year satellite record. Continuing a pattern below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island. In the Antarctic, record low monthly surface pressures were broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high surface pressure records for August and November were set at several stations. During this period, record low daily and monthly sea ice extents were observed, with the November mean sea ice extent more than 5 standard deviations below the 1981-2010 average. These record low sea ice values contrast sharply with the record high values observed during 2012-14. Over the region, springtime Antarctic stratospheric ozone depletion was less severe relative to the 1991-2006 average, but ozone levels were still low compared to pre-1990 levels. Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981-2010 average of 82, but fewer than the 101 storms recorded in 2015. Three basins-the North Atlantic, and eastern and western North Pacific-experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite era in 1970. Overall, four tropical cyclones reached the Saffir-Simpson category 5 intensity level. The strong El Nino at the beginning of the year that transitioned to a weak La Nina contributed to enhanced precipitation variability around the world. Wet conditions were observed throughout the year across southern South America, causing repeated heavy flooding in Argentina, Paraguay, and Uruguay. Wetter-than-usual conditions were also observed for eastern Europe and central Asia, alleviating the drought conditions of 2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after being plagued by drought for several years. Even so, the area covered by drought in 2016 at the global scale was among the largest in the post-1950 record. For each month, at least 12% of land surfaces experienced severe drought conditions or worse, the longest such stretch in the record. In northeastern Brazil, drought conditions were observed for the fifth consecutive year, making this the longest drought on record in the region. Dry conditions were also observed in western Bolivia and Peru; it was Bolivia's worst drought in the past 25 years. In May, with abnormally warm and dry conditions already prevailing over western Canada for about a year, the human-induced Fort McMurray wildfire burned nearly 590000 hectares and became the costliest disaster in Canadian history, with $3 billion (U.S. dollars) in insured losses.
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| 4. |
- Arndt, D. S., et al.
(author)
-
STATE OF THE CLIMATE IN 2017
- 2018
-
In: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
-
Research review (peer-reviewed)
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| 5. |
- Bauer, Florian, et al.
(author)
-
Depth of interaction with a 3-dimensional checkerboard arrangement LSO-LSO block
- 2010
-
In: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 57:3, s. 971-975
-
Journal article (peer-reviewed)abstract
- In order to improve image quality in Positron Emission Tomography (PET) different routes are being pursued such as fast timing resolution for time-of-flight PET, higher spatial resolution by the use of smaller scintillator pixels and the use of depth-of-interaction information. The detection of the depth-of-interaction (DOI) of a gamma ray within a detector, deploying pulse shape discrimination (PSD), has been used to increase sensitivity and spatial resolution, especially at the edge of the field of view (FOV). The DOI information is used to reduce the parallax error; thus improving spatial resolution. Commonly, different scintillator materials with different decay times and light output and other differentiating factors, such as density, emission spectra, etc. are used for DOI detectors. We present a multi-layer phoswich detector comprised of LSO with different decay times in the range from 30 ns to 47 ns. The difference in decay times is achieved by co-doping LSO:Ce with Ca, resulting in short decay times of ~ 30 ns [1]. The use of a cut light guide allows the use of regular Photomultiplier tubes, giving the opportunity of a potential DOI detector replacement for current detectors. We were able to identify each pixel in the different detector layers
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| 6. |
- Bauer, Florian, 1975-, et al.
(author)
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Evaluation of a Micro-Channel Plate PMT in PET
- 2006
-
In: Nuclear Science Symposium Conference Record, 2006, IEEE. - 1424405602 ; , s. 2503-2505
-
Conference paper (peer-reviewed)abstract
- The focus of this paper is the evaluation of micro-channel plate PMTs for PET detectors. Several properties of MCPs make them interesting for PET applications, such as fast time response, high spatial resolution, compact size, low susceptibility to magnetic fields, high gain and low power consumption. The preliminary tests in this paper are performed with the 51 mm times 51 mm square Burle 85011-501 assembly with 64 anodes (8 times 8). A new version of this MCP will be examined for the full paper. Initial measurements have been performed with a pulsed LASER (Hamamatsu Picosecond Light Pulser PLP-10 with M8903 Laser diode head). The engineering sample of the 85011 exhibited a time resolution of 26 ps. Further measurements will be performed, such as transit time measurements and timing measurements with scintillators. Single-photon timing measurements were presented earlier in [Ref. 1], from the old version as well as the suitability of the device in Cherenkov detectors in [Ref. 2]. For the full paper it is also planned to develop a circuit which allows lossless splitting of the anode signal.
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| 7. |
- Burkhardt, Lukas, et al.
(author)
-
Electronic Structure of the Hieber Anion [Fe(CO)3(NO)]− Revisited by X‐ray Emission and Absorption Spectroscopy
- 2020
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:6, s. 3551-3561
-
Journal article (peer-reviewed)abstract
- While the Hieber anion [Fe(CO)3(NO)]− has been reincarnated in the last years as an active catalyst in organic synthesis, there is still a debate about the oxidation state of the central Fe atom and the resulting charge of the NO ligand. To shed new light on this question and to understand the Fe−NO interaction in the Hieber anion, it is investigated in comparison to the formal 3d8 reference Fe(CO)5 and the formal 3d10 reference [Fe(CO)4]2− by the combination of valence-to-core X-ray emission spectroscopy (VtC-XES), X-ray absorption near-edge structure spectroscopy (XANES), and high-energy-resolution fluorescence-detected XANES. In order to extract information about the electronic structure, time-dependent density functional theory and ground-state density functional theory calculations are applied. This combination of experimental and computational methods reveals that the electron density at the Fe center of the Hieber resembles that of the isoelectronic [Fe(CO)4]2−. These observations challenge recent descriptions of the Hieber anion and reopen the debate about the experimentally and computationally determined Fe oxidation state and charge on the NO ligand.
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| 8. |
- de Jong, Roelof S., et al.
(author)
-
4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
-
In: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
-
Conference paper (peer-reviewed)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
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| 9. |
- Dierks, Philipp, et al.
(author)
-
Ground- And Excited-State Properties of Iron(II) Complexes Linked to Organic Chromophores
- 2020
-
In: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 59:20, s. 14746-14761
-
Journal article (peer-reviewed)abstract
- Two new bichromophoric complexes, [Fe(bim-ant)2]2+ and [Fe(bim-pyr)2]2+ ([H2-bim]2+ = 1,1′-(pyridine-2,6-diyl)bis(3-methyl-1H-imidazol-3-ium); ant = 9-anthracenyl; pyr = 1-pyrenyl), are investigated to explore the possibility of tuning the excited-state behavior in photoactive iron(II) complexes to design substitutes for noble-metal compounds. The ground-state properties of both complexes are characterized thoroughly by electrochemical methods and optical absorption spectroscopy, complemented by time-dependent density functional theory calculations. The excited states are investigated by static and time-resolved luminescence and femtosecond transient absorption spectroscopy. Both complexes exhibit room temperature luminescence, which originates from singlet states dominated by the chromophore (1Chrom). In the cationic pro-ligands and in the iron(II) complexes, the emission is shifted to red by up to 110 nm (5780 cm-1). This offers the possibility of tuning the organic chromophore emission by metal-ion coordination. The fluorescence lifetimes of the complexes are in the nanosecond range, while triplet metal-to-ligand charge-transfer (3MLCT) lifetimes are around 14 ps. An antenna effect as in ruthenium(II) polypyridine complexes connected to an organic chromophore is found in the form of an internal conversion within 3.4 ns from the 1Chrom to the 1MLCT states. Because no singlet oxygen forms from triplet oxygen in the presence of the iron(II) complexes and light, efficient intersystem crossing to the triplet state of the organic chromophore (3Chrom) is not promoted in the iron(II) complexes.
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| 10. |
- Dolfi, Michele, et al.
(author)
-
Matrix Product State applications for the ALPS project
- 2014
-
In: Computer Physics Communications. - : Elsevier BV. - 0010-4655 .- 1879-2944. ; 185:12, s. 3430-3440
-
Journal article (peer-reviewed)abstract
- The density-matrix renormalization group method has become a standard computational approach to the low-energy physics as well as dynamics of low-dimensional quantum systems. In this paper, we present a new set of applications, available as part of the ALPS package, that provide an efficient and flexible implementation of these methods based on a matrix product state (MPS) representation. Our applications implement, within the same framework, algorithms to variationally find the ground state and low-lying excited states as well as simulate the time evolution of arbitrary one-dimensional and two-dimensional models. Implementing the conservation of quantum numbers for generic Abelian symmetries, we achieve performance competitive with the best codes in the community. Example results are provided for (i) a model of itinerant fermions in one dimension and (ii) a model of quantum magnetism. PROGRAM SUMMARY Program title: ALPS MPS Catalogue identifier: AEUL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEUL_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Use of ‘mps optim’, ‘mps tevol’, ‘mps meas’ or ‘mps overlap’ requires citation of this paper. Use of any ALPS program requires citation of the ALPS [1] paper. No. of lines in distributed program, including test data, etc.: 373799 No. of bytes in distributed program, including test data, etc.: 2019043 Distribution format: tar.gz Programming language: C++, OpenMP for parallelization. Computer: PC, HPC cluster. Operating system: Any, tested on Linux, Mac OS X and Windows. Has the code been vectorized or parallelized?: Parallelized using OpenMP 1 to 24 processors used. RAM: 100 MB–100 GB. Classification: 7.7. External routines: ALPS [1, 2], BLAS/LAPACK, HDF5. Nature of problem: Solution of quantum many-body systems is generally a hard problem. The many-body Hilbert space grows exponentially with the system size which limits exact diagonalization results to only 20–40 spins, and the fermionic negative sign problem limits the Quantum Monte Carlo methods to a few special cases. Solution method: The matrix product states ansatz provides a controllable truncation of the Hilbert space which makes it currently the method of choice to investigate low-dimensional systems in condensed matter physics. Our implementation allows simulation of arbitrary one-dimensional and two-dimensional models and achieves performance competitive with the best codes in the community. We implement conservation of quantum numbers for generic Abelian symmetries. Running time: 10 s–8h per sweep. References: [1] B. Bauer, et al. (ALPS Collaboration), The ALPS project release 2.0: open source software for strongly correlated systems, J. Stat. Mech. 2011 (05) (2011) P05001. http://dx.doi.org/10.1088/1742-5468/2011/05/P05001. [2] http://alps.comp-phys.org.
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| 11. |
- Dolfi, Michele, et al.
(author)
-
Minimizing nonadiabaticities in optical-lattice loading
- 2015
-
In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 91:3
-
Journal article (peer-reviewed)abstract
- In the quest to reach lower temperatures of ultracold gases in optical-lattice experiments, nonadiabaticities during lattice loading represent one of the limiting factors that prevent the same low temperatures being reached as in experiments without lattices. Simulating the loading of a bosonic quantum gas into a one-dimensional optical lattice with and without a trap, we find that the redistribution of atomic density inside a global confining potential is by far the dominant source of heating. Based on these results we propose adjusting the trapping potential during loading to minimize changes to the density distribution. Our simulations confirm that a very simple linear interpolation of the trapping potential during loading already significantly decreases the heating of a quantum gas, and we discuss how loading protocols minimizing density redistributions can be designed.
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| 12. |
- Feng, Yanyue, 1993, et al.
(author)
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Synthesis and Characterization of Catalytically Active Au Core─Pd Shell Nanoparticles Supported on Alumina
- 2022
-
In: Langmuir. - : American Chemical Society (ACS). - 1520-5827 .- 0743-7463. ; 38:42, s. 12859-12870
-
Journal article (peer-reviewed)abstract
- A two-step seeded-growth method was refined to synthesize Au@Pd core@shell nanoparticles with thin Pd shells, which were then deposited onto alumina to obtain a supported Au@Pd/Al2O3 catalyst active for prototypical CO oxidation. By the strict control of temperature and Pd/Au molar ratio and the use of l-ascorbic acid for making both Au cores and Pd shells, a 1.5 nm Pd layer is formed around the Au core, as evidenced by transmission electron microscopy and energy-dispersive spectroscopy. The core@shell structure and the Pd shell remain intact upon deposition onto alumina and after being used for CO oxidation, as revealed by additional X-ray diffraction and X-ray photoemission spectroscopy before and after the reaction. The Pd shell surface was characterized with in situ infrared (IR) spectroscopy using CO as a chemical probe during CO adsorption-desorption. The IR bands for CO ad-species on the Pd shell suggest that the shell exposes mostly low-index surfaces, likely Pd(111) as the majority facet. Generally, the IR bands are blue-shifted as compared to conventional Pd/alumina catalysts, which may be due to the different support materials for Pd, Au versus Al2O3, and/or less strain of the Pd shell. Frequencies obtained from density functional calculations suggest the latter to be significant. Further, the catalytic CO oxidation ignition-extinction processes were followed by in situ IR, which shows the common CO poisoning and kinetic behavior associated with competitive adsorption of CO and O2 that is typically observed for noble metal catalysts.
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| 13. |
- Fogelström, Mikael, 1963, et al.
(author)
-
Two-channel point-contact tunneling theory of superconductors
- 2014
-
In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 90:10, s. 104512-
-
Journal article (peer-reviewed)abstract
- We introduce a two-channel tunneling model to generalize the widely used BTK theory of point-contact conductance between a normal metal contact and superconductor. Tunneling of electrons can occur via localized surface states or directly, resulting in a Fano resonance in the differential conductance G = d I /d V . We present an analysis of G within the two-channel model when applied to soft point contacts between normal metallic silver particles and prototypical heavy-fermion superconductors CeCoIn5 and CeRhIn5 at high pressures. In the normal state the Fano line shape of the measured G is well described by a model with two tunneling channels and a large temperature-independent background conductance. In the superconducting state a strongly suppressed Andreev reflection signal is explained by the presence of the background conductance. We report Andreev signal in CeCoIn5 consistent with standard dx2−y2 -wave pairing, assuming an equal mixture of tunneling into [100] and [110] crystallographic interfaces, whereas in CeRhIn5 at 1.8 and 2.0 GPa the signal is described by a dx2−y2 -wave gap with reduced nodal region, i.e., increased slope of the gap opening on the Fermi surface. A possibility is that the shape of the high-pressure Andreev signal is affected by the proximity of a line of quantum critical points that extends from 1.75 to 2.3 GPa, which is not accounted for in our description of the heavy-fermion superconductor.
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| 14. |
- Garmroudi, Fabian, et al.
(author)
-
Anderson transition in stoichiometric Fe2VAl : high thermoelectric performance from impurity bands
- 2022
-
In: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
-
Journal article (peer-reviewed)abstract
- The mathematical conditions for the best thermoelectric is well known but never realised in real materials. Here, the authors propose the Anderson transition in a narrow impurity band as a physical realisation of this seemingly unrealisable scenario. Discovered more than 200 years ago in 1821, thermoelectricity is nowadays of global interest as it enables direct interconversion of thermal and electrical energy via the Seebeck/Peltier effect. In their seminal work, Mahan and Sofo mathematically derived the conditions for 'the best thermoelectric'-a delta-distribution-shaped electronic transport function, where charge carriers contribute to transport only in an infinitely narrow energy interval. So far, however, only approximations to this concept were expected to exist in nature. Here, we propose the Anderson transition in a narrow impurity band as a physical realisation of this seemingly unrealisable scenario. An innovative approach of continuous disorder tuning allows us to drive the Anderson transition within a single sample: variable amounts of antisite defects are introduced in a controlled fashion by thermal quenching from high temperatures. Consequently, we obtain a significant enhancement and dramatic change of the thermoelectric properties from p-type to n-type in stoichiometric Fe2VAl, which we assign to a narrow region of delocalised electrons in the energy spectrum near the Fermi energy. Based on our electronic transport and magnetisation experiments, supported by Monte-Carlo and density functional theory calculations, we present a novel strategy to enhance the performance of thermoelectric materials.
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| 15. |
- Gaskell, George, et al.
(author)
-
Biotechnology and the European public
- 2000
-
In: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 18:9, s. 935-938
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Journal article (peer-reviewed)abstract
- The latest European sample survey of public perceptions of biotechnology reveals widespread opposition to genetically modified (GM) food in much of Europe, but public attitudes to medical and environmental applications remain positive.
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| 16. |
- Goudzovski, Evgueni, et al.
(author)
-
New physics searches at kaon and hyperon factories
- 2023
-
In: Reports on progress in physics (Print). - : Institute of Physics (IOP). - 0034-4885 .- 1361-6633. ; 86:1
-
Research review (peer-reviewed)abstract
- Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors.
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| 17. |
- Guo, Jeff, et al.
(author)
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DockStream: a docking wrapper to enhance de novo molecular design
- 2021
-
In: Journal of Cheminformatics. - : Springer Science and Business Media LLC. - 1758-2946 .- 1758-2946. ; 13:1
-
Journal article (peer-reviewed)abstract
- Recently, we have released the de novo design platform REINVENT in version 2.0. This improved and extended iteration supports far more features and scoring function components, which allows bespoke and tailor-made protocols to maximize impact in small molecule drug discovery projects. A major obstacle of generative models is producing active compounds, in which predictive (QSAR) models have been applied to enrich target activity. However, QSAR models are inherently limited by their applicability domains. To overcome these limitations, we introduce a structure-based scoring component for REINVENT. DockStream is a flexible, stand-alone molecular docking wrapper that provides access to a collection of ligand embedders and docking backends. Using the benchmarking and analysis workflow provided in DockStream, execution and subsequent analysis of a variety of docking configurations can be automated. Docking algorithms vary greatly in performance depending on the target and the benchmarking and analysis workflow provides a streamlined solution to identifying productive docking configurations. We show that an informative docking configuration can inform the REINVENT agent to optimize towards improving docking scores using public data. With docking activated, REINVENT is able to retain key interactions in the binding site, discard molecules which do not fit the binding cavity, harness unused (sub-)pockets, and improve overall performance in the scaffold-hopping scenario. The code is freely available at https://github.com/MolecularAI/DockStream.
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| 18. |
- Görlin, Mikaela, et al.
(author)
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Key activity descriptors of nickel-iron oxygen evolution electrocatalysts in the presence of alkali metal cations
- 2020
-
In: Nature Communications. - : Springer Nature. - 2041-1723. ; 11:1
-
Journal article (peer-reviewed)abstract
- Efficient oxygen evolution reaction (OER) electrocatalysts are pivotal for sustainable fuel production, where the Ni-Fe oxyhydroxide (OOH) is among the most active catalysts for alkaline OER. Electrolyte alkali metal cations have been shown to modify the activity and reaction intermediates, however, the exact mechanism is at question due to unexplained deviations from the cation size trend. Our X-ray absorption spectroelectrochemical results show that bigger cations shift the Ni2+/(3+delta)+ redox peak and OER activity to lower potentials (however, with typical discrepancies), following the order CsOH>NaOH approximate to KOH>RbOH>LiOH. Here, we find that the OER activity follows the variations in electrolyte pH rather than a specific cation, which accounts for differences both in basicity of the alkali hydroxides and other contributing anomalies. Our density functional theory-derived reactivity descriptors confirm that cations impose negligible effect on the Lewis acidity of Ni, Fe, and O lattice sites, thus strengthening the conclusions of an indirect pH effect. It is commonly accepted that electrolyte alkali metal cations modify the catalytic activity for oxygen evolution reaction. Here the authors challenge this assumption, showing that the activity is actually affected by a change in the electrolyte pH rather than a specific alkali cation.
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| 19. |
- Hartkopf, Andreas D., et al.
(author)
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Disseminated tumour cells from the bone marrow of early breast cancer patients : Results from an international pooled analysis
- 2021
-
In: European Journal of Cancer. - : Elsevier BV. - 0959-8049. ; 154, s. 128-137
-
Journal article (peer-reviewed)abstract
- Purpose: Presence of disseminated tumour cells (DTCs) in the bone marrow (BM) has been described as a surrogate of residual disease in patients with early breast cancer (EBC). PADDY (Pooled Analysis of DTC Detection in Early Breast Cancer) is a large international analysis of pooled data that aimed to assess the prognostic impact of DTCs in patients with EBC. Experimental design: Individual patient data were collected from 11 centres. Patients with EBC and available follow-up data in whom BM sampling was performed at the time of primary diagnosis before receiving any anticancer treatment were eligible. DTCs were identified by antibody staining against epithelial cytokeratins. Multivariate Cox regression was used to compare the survival of DTC-positive versus DTC-negative patients. Results: In total, 10,307 patients were included. Of these, 2814 (27.3%) were DTC-positive. DTC detection was associated with higher tumour grade, larger tumour size, nodal positivity, oestrogen receptor and progesterone receptor negativity, and HER2 positivity (all p < 0.001). Multivariate analyses showed that DTC detection was an independent prognostic marker for overall survival, disease-free survival and distant disease-free survival with hazard ratios (HR) and 95% confidence intervals (CI) of 1.23 (95% CI: 1.06–1.43, p = 0.006), 1.30 (95% CI: 1.12–1.52, p < 0.001) and 1.30 (95% CI: 1.08–1.56, p = 0.006), respectively. There was no association between locoregional relapse-free survival and DTC detection (HR 1.21; 95% CI 0.68–2.16; p = 0.512). Conclusions: DTCs in the BM represent an independent prognostic marker in patients with EBC. The heterogeneous metastasis-initiating potential of DTCs is consistent with the concept of cancer dormancy.
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| 20. |
- Haynes, Roger, et al.
(author)
-
The 4MOST instrument concept overview
- 2014
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In: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147, s. 91476-91476
-
Conference paper (peer-reviewed)abstract
- The 4MOST([1]) instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x10(6) spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z similar to 5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of similar to 1600 targets at R similar to 5,000 from 390-900nm and similar to 800 targets at R>18,000 in three channels between similar to 395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of similar to 4.1 degrees2. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: opto-mechanical, control, data management and operations concepts; and initial performance estimates.
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| 21. |
- Johansson, Niklas, et al.
(author)
-
Tracking linguistic primitives : The phonosemantic realization of fundamental oppositional pairs
- 2017
-
In: Dimensions of Iconicity. - Amsterdam : John Benjamins Publishing Company. - 1873-5037. - 9789027265180 ; 15, s. 39-62
-
Book chapter (peer-reviewed)abstract
- This paper investigates how cross-linguistic phoneme distributions of 56 fundamental oppositional concepts can reveal semantic relationships by looking into the linguistic forms of 75 genetically and areally distributed languages. Based on proposals of semantic primes (Goddard & Wierzbicka 2002), reduced Swadesh lists (Holman et al. 2008), presumed ultraconservative words (Pagel et al. 2013), attested basic antonyms (Paradis, Willners & Jones 2009) and sense perception words, semantic oppositional pairs were selected. Phonemes were divided according to: the frequency of vowels’ second formant and consonants’ energy accumulation, sonority, a combination of the aforementioned two, and general phonetic traits, e.g. voicing. Using a biplot, the phonological relatedness between the investigated concepts was illustrated graphically, and the phoneme distributions’ over- and underrepresentation from the average was calculated for each concept. Salient semantic groupings and relations based solely on phonological contrasts were found for most investigated concepts, including the semantic domains: Small, Intense Vision-Touch, Large, Organic, Horizontal-Vertical Distance, Deictic, Containment, Gender, Parent and Diurnal, and the sole concept old. The most notable relations found were: mother/i vs. father, a three-way deictic distinction and a dimensional tripartite oppositional relationship. Embodiment, oppositional thinking and evidence for more general concepts to precede complex concepts were proposed as explanations for the results.
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| 22. |
- Kaiser, Matthias J., et al.
(author)
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Frequency of Malnutrition in Older Adults : A Multinational Perspective Using the Mini Nutritional Assessment
- 2010
-
In: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 58:9, s. 1734-1738
-
Journal article (peer-reviewed)abstract
- OBJECTIVES To provide pooled data on the prevalence of malnutrition in elderly people as evaluated using the Mini Nutritional Assessment (MNA). DESIGN Retrospective pooled analysis of previously published datasets. SETTING Hospital, rehabilitation, nursing home, community. PARTICIPANTS Four thousand five hundred seven people (75.2% female) with a mean age of 82.3. MEASUREMENTS The prevalence of malnutrition in the combined database and in the four settings was examined. RESULTS Twenty-four data sets with information on full MNA classification from researchers from 12 countries were submitted. In the combined database, the prevalence of malnutrition was 22.8%, with considerable differences between the settings (rehabilitation, 50.5%; hospital, 38.7%; nursing home, 13.8%; community, 5.8%). In the combined database, the "at risk" group had a prevalence of 46.2%. Consequently, approximately two-thirds of study participants were at nutritional risk or malnourished. CONCLUSION The MNA has gained worldwide acceptance and shows a high prevalence of malnutrition in different settings, except for the community. Because of its specific geriatric focus, the MNA should be recommended as the basis for nutritional evaluation in older people.
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| 23. |
- Kehoe, Laura, et al.
(author)
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Make EU trade with Brazil sustainable
- 2019
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 364:6438, s. 341-
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Journal article (other academic/artistic)
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| 24. |
- Koegl, Matthias, et al.
(author)
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Analysis of the LIF/Mie ratio from individual droplets for planar droplet sizing : Application to gasoline fuels and their mixtures with ethanol
- 2019
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In: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 9:22
-
Journal article (peer-reviewed)abstract
- In this work, the possibility of using planar droplet sizing (PDS) based on laser-induced fluorescence (LIF) and Mie scattering was investigated within the framework of measuring the droplet Sauter mean diameter (SMD) of direct-injection spark-ignition (DISI) spray systems. For this purpose, LIF and Mie signals of monodisperse fuel droplets produced by a droplet generator were studied at engine relevant diameters (20-50 μm). The surrogate gasoline fuel Toliso (consisting of 65 vol. % isooctane, 35 vol. % toluene) and the biofuel blend E20 (consisting of 80 vol. % Toliso, 20 vol. % ethanol) were used and which were doped with the fluorescence dye "nile red". The effects of ethanol admixture, dye concentration, laser power, and temperature variation on the LIF/Mie ratio were studied simultaneously at both macroscopic and microscopic scale. The deduced calibration curves of the LIF and Mie signals of both fuels showed volumetric and surface dependent behaviors, respectively, in accordance with the assumptions in the literature. The existence of glare points and morphology-dependent resonances (MDRs) lead to slightly higher LIF and Mie exponents of E20 in comparison to Toliso. In principle, these calibration curves enable the determination of the SMD from LIF/Mie ratio images of transient fuel sprays.
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| 25. |
- Laska, Matthias, 1960-, et al.
(author)
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Self-anointing behavior in free-ranging spider monkeys (Ateles geoffroyi) in Mexico
- 2007
-
In: Primates. - : Springer Science and Business Media LLC. - 0032-8332 .- 1610-7365. ; 48:2, s. 160-163
-
Journal article (peer-reviewed)abstract
- During 250 h of observation, a total of 20 episodes of self-anointing, that is, the application of scent-bearing material onto the body, were recorded in a group of free-ranging Mexican spider monkeys (Ateles geoffroyi). The animals used the leaves of three species of plants (Brongniartia alamosana, Fabaceae; Cecropia obtusifolia, Cecropiaceae; and Apium graveolens, Umbelliferae) two of which have not been reported so far in this context in any New World primate species. The findings that only two males displayed self-anointing, that only the sternal and axillary regions of the body were rubbed with the mix of saliva and plant material, and a lack of correlation between the occurrence of self-anointing and time of day, season of the year, ambient temperature or humidity do not fit the hypothesis that this behavior functions in repelling insects and/or mitigating topical skin infections in this species. Rather, the data and the observation that the leaves of all three plant species spread an intensive and aromatic odor when crushed, support the hypothesis that self-anointing in A. geoffroyi may play a role in the context of social communication, possibly for signaling of social status or to increase sexual attractiveness.
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| 26. |
- Längin, Matthias, et al.
(author)
-
Consistent success in life-supporting porcine cardiac xenotransplantation
- 2018
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 564:7736, s. 430-433
-
Journal article (peer-reviewed)abstract
- Heart transplantation is the only cure for patients with terminal cardiac failure, but the supply of allogeneic donor organs falls far short of the clinical need1–3. Xenotransplantation of genetically modified pig hearts has been discussed as a potential alternative4. Genetically multi-modified pig hearts that lack galactose-α1,3-galactose epitopes (α1,3-galactosyltransferase knockout) and express a human membrane cofactor protein (CD46) and human thrombomodulin have survived for up to 945 days after heterotopic abdominal transplantation in baboons5. This model demonstrated long-term acceptance of discordant xenografts with safe immunosuppression but did not predict their life-supporting function. Despite 25 years of extensive research, the maximum survival of a baboon after heart replacement with a porcine xenograft was only 57 days and this was achieved, to our knowledge, only once6. Here we show that α1,3-galactosyltransferase-knockout pig hearts that express human CD46 and thrombomodulin require non-ischaemic preservation with continuous perfusion and control of post-transplantation growth to ensure long-term orthotopic function of the xenograft in baboons, the most stringent preclinical xenotransplantation model. Consistent life-supporting function of xenografted hearts for up to 195 days is a milestone on the way to clinical cardiac xenotransplantation7.
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| 27. |
- Martin, Natalia Mihaela, 1984, et al.
(author)
-
Structure-function relationship during CO2 methanation over Rh/Al2O3 and Rh/SiO2 catalysts at atmospheric pressure conditions
- 2018
-
In: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 8:10, s. 2686-2696
-
Journal article (peer-reviewed)abstract
- The effect of support material and chemical state of Rh for Rh/Al2O3 and Rh/SiO2 model catalysts during CO2 hydrogenation were studied by a combined array of in situ characterisation techniques including diffuse reflectance infrared Fourier transform spectroscopy, energy-dispersive X-ray absorption spectroscopy and high-energy X-ray diffraction at 250-350 °C and atmospheric pressure. The CO2 methanation proceeds via intermediate formation of adsorbed CO species on metallic Rh likely followed by their hydrogenation to methane. Linearly-bonded CO species is suggested to be a more active precursor in the hydrogenation compared to the bridge-bonded species, which seems to relate to particle size effects: for larger particles mainly the formation of inactive bridge-bonded CO species takes place. Further, analysis of the chemical state of Rh during reaction conditions reveal a minor formation of RhOx from dissociation of CO2 , which is a consequence of the increased activity observed over Rh/Al2O3 catalyst.
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| 28. |
- Martin, Natalia M., et al.
(author)
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Structure-function relationship for CO2 methanation over ceria supported Rh and Ni catalysts under atmospheric pressure conditions
- 2019
-
In: Catalysis Science & Technology. - : Royal Society of Chemistry. - 2044-4753 .- 2044-4761. ; 9:7, s. 1644-1653
-
Journal article (peer-reviewed)abstract
- In situ structural and chemical state characterization of Rh/CeO2 and Ni/CeO2 catalysts during atmospheric pressure CO2 methanation has been performed by a combined array of time-resolved analytical techniques including ambient-pressure X-ray photoelectron spectroscopy, high-energy X-ray diffraction and diffuse reflectance infrared Fourier transform spectroscopy. The ceria phase is partially reduced during the CO2 methanation and in particular Ce3+ species seem to facilitate activation of CO2 molecules. The activated CO2 molecules then react with atomic hydrogen provided from H-2 dissociation on Rh and Ni sites to form formate species. For the most active catalyst (Rh/CeO2), transmission electron microscopy measurements show that the Rh nanoparticles are small (average 4 nm, but with a long tail towards smaller particles) due to a strong interaction between Rh particles and the ceria phase. In contrast, larger nanoparticles were observed for the Ni/CeO2 catalyst (average 6 nm, with no crystallites below 5 nm found), suggesting a weaker interaction with the ceria phase. The higher selectivity towards methane of Rh/CeO2 is proposed to be due to the stronger metal-support interaction.
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| 29. |
- Martin, Natalia Mihaela, 1984, et al.
(author)
-
Structure-function relationship for CO2 methanation over ceria supported Rh and Ni catalysts under atmospheric pressure conditions
- 2019
-
In: Catalysis Science and Technology. - 2044-4753 .- 2044-4761. ; 9:7, s. 1644-1653
-
Journal article (peer-reviewed)abstract
- In situ structural and chemical state characterization of Rh/CeO 2 and Ni/CeO 2 catalysts during atmospheric pressure CO 2 methanation has been performed by a combined array of time-resolved analytical techniques including ambient-pressure X-ray photoelectron spectroscopy, high-energy X-ray diffraction and diffuse reflectance infrared Fourier transform spectroscopy. The ceria phase is partially reduced during the CO 2 methanation and in particular Ce 3+ species seem to facilitate activation of CO 2 molecules. The activated CO 2 molecules then react with atomic hydrogen provided from H 2 dissociation on Rh and Ni sites to form formate species. For the most active catalyst (Rh/CeO 2 ), transmission electron microscopy measurements show that the Rh nanoparticles are small (average 4 nm, but with a long tail towards smaller particles) due to a strong interaction between Rh particles and the ceria phase. In contrast, larger nanoparticles were observed for the Ni/CeO 2 catalyst (average 6 nm, with no crystallites below 5 nm found), suggesting a weaker interaction with the ceria phase. The higher selectivity towards methane of Rh/CeO 2 is proposed to be due to the stronger metal-support interaction.
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| 30. |
- Moayyeri, Alireza, et al.
(author)
-
Genetic determinants of heel bone properties : genome-wide association meta-analysis and replication in the GEFOS/GENOMOS consortium
- 2014
-
In: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:11, s. 3054-3068
-
Journal article (peer-reviewed)abstract
- Quantitative ultrasound of the heel captures heel bone properties that independently predict fracture risk and, with bone mineral density (BMD) assessed by X-ray (DXA), may be convenient alternatives for evaluating osteoporosis and fracture risk. We performed a meta-analysis of genome-wide association (GWA) studies to assess the genetic determinants of heel broadband ultrasound attenuation (BUA; n = 14 260), velocity of sound (VOS; n = 15 514) and BMD (n = 4566) in 13 discovery cohorts. Independent replication involved seven cohorts with GWA data (in silico n = 11 452) and new genotyping in 15 cohorts (de novo n = 24 902). In combined random effects, meta-analysis of the discovery and replication cohorts, nine single nucleotide polymorphisms (SNPs) had genome-wide significant (P < 5 x 10(-8)) associations with heel bone properties. Alongside SNPs within or near previously identified osteoporosis susceptibility genes including ESR1 (6q25.1: rs4869739, rs3020331, rs2982552), SPTBN1 (2p16.2: rs11898505), RSPO3 (6q22.33: rs7741021), WNT16 (7q31.31: rs2908007), DKK1 (10q21.1: rs7902708) and GPATCH1 (19q13.11: rs10416265), we identified a new locus on chromosome 11q14.2 (rs597319 close to TMEM135, a gene recently linked to osteoblastogenesis and longevity) significantly associated with both BUA and VOS (P < 8.23 x 10(-14)). In meta-analyses involving 25 cohorts with up to 14 985 fracture cases, six of 10 SNPs associated with heel bone properties at P < 5 x 10(-6) also had the expected direction of association with any fracture (P < 0.05), including three SNPs with P < 0.005: 6q22.33 (rs7741021), 7q31.31 (rs2908007) and 10q21.1 (rs7902708). In conclusion, this GWA study reveals the effect of several genes common to central DXA-derived BMD and heel ultrasound/DXA measures and points to a new genetic locus with potential implications for better understanding of osteoporosis pathophysiology.
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| 31. |
- Moore, J. Harry, et al.
(author)
-
Icolos: a workflow manager for structure-based post-processing of de novo generated small molecules
- 2022
-
In: Bioinformatics. - : Oxford University Press (OUP). - 1367-4803 .- 1367-4811. ; 38:21, s. 4951-4952
-
Journal article (peer-reviewed)abstract
- A Summary: We present Icolos, a workflow manager written in Python as a tool for automating complex structure-based workflows for drug design. Icolos can be used as a standalone tool, for example in virtual screening campaigns, or can be used in conjunction with deep learning-based molecular generation facilitated for example by REINVENT, a previously published molecular de novo design package. In this publication, we focus on the internal structure and general capabilities of Icolos, using molecular docking experiments as an illustrative example.
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| 32. |
- Naumova, Maria A., et al.
(author)
-
Exploring the light-induced dynamics in solvated metallogrid complexes with femtosecond pulses across the electromagnetic spectrum
- 2020
-
In: The Journal of chemical physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 152:21
-
Journal article (peer-reviewed)abstract
- Oligonuclear complexes of d4-d7 transition metal ion centers that undergo spin-switching have long been developed for their practical role in molecular electronics. Recently, they also have appeared as promising photochemical reactants demonstrating improved stability. However, the lack of knowledge about their photophysical properties in the solution phase compared to mononuclear complexes is currently hampering their inclusion into advanced light-driven reactions. In the present study, the ultrafast photoinduced dynamics in a solvated [2 × 2] iron(II) metallogrid complex are characterized by combining measurements with transient optical-infrared absorption and x-ray emission spectroscopy on the femtosecond time scale. The analysis is supported by density functional theory calculations. The photocycle can be described in terms of intra-site transitions, where the FeII centers in the low-spin state are independently photoexcited. The Franck-Condon state decays via the formation of a vibrationally hot high-spin (HS) state that displays coherent behavior within a few picoseconds and thermalizes within tens of picoseconds to yield a metastable HS state living for several hundreds of nanoseconds. Systematic comparison with the closely related mononuclear complex [Fe(terpy)2]2+ reveals that nuclearity has a profound impact on the photoinduced dynamics. More generally, this work provides guidelines for expanding the integration of oligonuclear complexes into new photoconversion schemes that may be triggered by ultrafast spin-switching.
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| 33. |
- Naumova, Maria A., et al.
(author)
-
Revealing Hot and Long-Lived Metastable Spin States in the Photoinduced Switching of Solvated Metallogrid Complexes with Femtosecond Optical and X-ray Spectroscopies
- 2020
-
In: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 11:6, s. 2133-2141
-
Journal article (peer-reviewed)abstract
- An atomistic understanding of the photoinduced spin-state switching (PSS) within polynuclear systems of d4-d7 transition metal ion complexes is required for their rational integration into light-driven reactions of chemical and biological interest. However, in contrast to mononuclear systems, the multidimensional dynamics of the PSS in solvated molecular arrays have not yet been elucidated due to the expected complications associated with the connectivity between the metal centers and the strong interactions with the surroundings. In this work, the PSS in a solvated triiron(II) metallogrid complex is characterized using transient optical absorption and X-ray emission spectroscopies on the femtosecond time scale. The complementary measurements reveal the photoinduced creation of energy-rich (hot) and long-lived quintet states, whose dynamics differ critically from their mononuclear congeners. This finding opens major prospects for developing novel schemes in solution-phase spin chemistry that are driven by the dynamic PSS process in compact oligometallic arrays.
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| 34. |
- Naumova, M., et al.
(author)
-
Structural dynamics upon photoexcitation-induced charge transfer in a dicopper(i)-disulfide complex
- 2018
-
In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 20:9, s. 6274-6286
-
Journal article (peer-reviewed)abstract
- The structural dynamics of charge-transfer states of nitrogen-ligated copper complexes has been extensively investigated in recent years following the development of pump-probe X-ray techniques. In this study we extend this approach towards copper complexes with sulfur coordination and investigate the influence of charge transfer states on the structure of a dicopper(i) complex with coordination by bridging disulfide ligands and additionally tetramethylguanidine units [Cu I 2 (NSSN) 2 ] 2+ . In order to directly observe and refine the photoinduced structural changes in the solvated complex we applied picosecond pump-probe X-ray absorption spectroscopy (XAS) and wide-angle X-ray scattering (WAXS). Additionally, the ultrafast evolution of the electronic excited states was monitored by femtosecond transient absorption spectroscopy in the UV-Vis probe range. DFT calculations were used to predict molecular geometries and electronic structures of the ground and metal-to-ligand charge transfer states with singlet and triplet spin multiplicities, i.e. S 0 , 1 MLCT and 3 MLCT, respectively. Combining these techniques we elucidate the electronic and structural dynamics of the solvated complex upon photoexcitation to the MLCT states. In particular, femtosecond optical transient spectroscopy reveals three distinct timescales of 650 fs, 10 ps and > 100 ps, which were assigned as internal conversion to the ground state (S n → S 0 ), intersystem crossing 1 MLCT → 3 MLCT, and subsequent relaxation of the triplet to the ground state, respectively. Experimental data collected using both X-ray techniques are in agreement with the DFT-predicted structure for the triplet state, where coordination bond lengths change and one of the S-S bridges is cleaved, causing the movement of two halves of the molecule relative to each other. Extended X-ray absorption fine structure spectroscopy resolves changes in Cu-ligand bond lengths with precision on the order of 0.01 Å, whereas WAXS is sensitive to changes in the global shape related to relative movement of parts of the molecule. The results presented herein widen the knowledge on the electronic and structural dynamics of photoexcited copper-sulfur complexes and demonstrate the potential of combining the pump-probe X-ray absorption and scattering for studies on photoinduced structural dynamics in copper-based coordination complexes.
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| 35. |
- Neesse, Albrecht, et al.
(author)
-
Stromal biology and therapy in pancreatic cancer : ready for clinical translation?
- 2019
-
In: Gut. - : BMJ Publishing Group Ltd. - 0017-5749 .- 1468-3288. ; 68:1, s. 159-171
-
Journal article (peer-reviewed)abstract
- Pancreatic ductal adenocarcinoma (PDA) is notoriously aggressive and hard to treat. The tumour microenvironment (TME) in PDA is highly dynamic and has been found to promote tumour progression, metastasis niche formation and therapeutic resistance. Intensive research of recent years has revealed an incredible heterogeneity and complexity of the different components of the TME, including cancer-associated fibroblasts, immune cells, extracellular matrix components, tumour vessels and nerves. It has been hypothesised that paracrine interactions between neoplastic epithelial cells and TME compartments may result in either tumour-promoting or tumour-restraining consequences. A better preclinical understanding of such complex and dynamic network systems is required to develop more powerful treatment strategies for patients. Scientific activity and the number of compelling findings has virtually exploded during recent years. Here, we provide an update of the most recent findings in this area and discuss their translational and clinical implications for basic scientists and clinicians alike.
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| 36. |
-
Overview of the JET results
- 2015
-
In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 55:10
-
Journal article (peer-reviewed)
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| 37. |
- Palazzo, Natascia, et al.
(author)
-
Investigation of soot formation in a novel diesel fuel burner
- 2019
-
In: Energies. - : MDPI AG. - 1996-1073. ; 12:10
-
Journal article (peer-reviewed)abstract
- In the present work, a novel burner capable of complete pre-vaporization and stationary combustion of diesel fuel in a laminar diffusion flame has been developed to investigate the effect of the chemical composition of diesel fuel on soot formation. For the characterization of soot formation during diesel combustion we performed a comprehensive morphological characterization of the soot and determined its concentration by coupling elastic light scattering (ELS) and laser-induced incandescence (LII) measurements. With ELS, radii of gyration of aggregates were measured within a point-wise measurement volume, LII was employed in an imaging approach for a 2D-analysis of the soot volume fraction. We carried out LII and ELS measurements at different positions in the flame for two different fuel types, revealing the effects of small modifications of the fuel composition on soot emission during diesel combustion.
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| 38. |
- Seng, Olaf, et al.
(author)
-
Search-based Improvement of Subsystem Decompositions
- 2005
-
In: GECCO 2005. - New York, NY, USA : ACM. ; , s. 1045-1051
-
Conference paper (other academic/artistic)abstract
- The subsystem decomposition of a software system degrades gradually during its lifetime and therefore it gets harder and harder to maintain. As a result this decomposition needs to be reconditioned from time to time. The problem is to determine a suitable subsystem decomposition that can be used as a basis for future maintenance tasks. This paper describes a new methodology that computes such a subsystem decomposition by optimizing metrics and heuristics of good subsystem design. The main idea is to treat this task as a search problem and to solve it using a genetic algorithm.
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| 39. |
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| 40. |
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| 41. |
- Thompson, Paul M., et al.
(author)
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The ENIGMA Consortium : large-scale collaborative analyses of neuroimaging and genetic data
- 2014
-
In: BRAIN IMAGING BEHAV. - : Springer Science and Business Media LLC. - 1931-7557 .- 1931-7565. ; 8:2, s. 153-182
-
Journal article (peer-reviewed)abstract
- The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) Consortium is a collaborative network of researchers working together on a range of large-scale studies that integrate data from 70 institutions worldwide. Organized into Working Groups that tackle questions in neuroscience, genetics, and medicine, ENIGMA studies have analyzed neuroimaging data from over 12,826 subjects. In addition, data from 12,171 individuals were provided by the CHARGE consortium for replication of findings, in a total of 24,997 subjects. By meta-analyzing results from many sites, ENIGMA has detected factors that affect the brain that no individual site could detect on its own, and that require larger numbers of subjects than any individual neuroimaging study has currently collected. ENIGMA's first project was a genome-wide association study identifying common variants in the genome associated with hippocampal volume or intracranial volume. Continuing work is exploring genetic associations with subcortical volumes (ENIGMA2) and white matter microstructure (ENIGMA-DTI). Working groups also focus on understanding how schizophrenia, bipolar illness, major depression and attention deficit/hyperactivity disorder (ADHD) affect the brain. We review the current progress of the ENIGMA Consortium, along with challenges and unexpected discoveries made on the way.
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| 42. |
- Zimmer, Peter, et al.
(author)
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Towards Noble-Metal-Free Dyads : Ground and Excited State Tuning by a Cobalt Dimethylglyoxime Motif Connected to an Iron N-Heterocyclic Carbene Photosensitizer
- 2018
-
In: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-0682. ; 2018:48, s. 5203-5214
-
Journal article (peer-reviewed)abstract
- Heteroleptic iron based complexes bearing the 2,6-bis[3-(2,6-diisopropylphenyl)imidazol-2-ylidene]pyridine motif and a polypridine ligand have been synthesized and characterized in their ground and excited state. This series of complexes includes a first example of a hetero-bimetallic complex connecting an iron N-heterocyclic carbene photosensitizer with a cobalt dimethylglyoxime fragment. Focus is set on the influence of the linker and cobalt center as second ligand at the iron center on the photophysics. While electronic absorption spectroscopy and cyclic voltammetry reveal a weak mutual influence of the single ligands in the heteroleptic complexes, an increasing MLCT lifetime with larger π-accepting abilities was found by time-resolved transient absorption spectroscopy, with maximum lifetime in the case of the hetero-bimetallic dyad. Concurrently the MC lifetimes were observed to decrease. The reported results will allow to develop guidelines for designing bimetallic devices, which may allow electron transfer from the photosensitizer fragment to a catalytically active center.
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