MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and ...biology. The elliptical vertically focusing guide allows one to measure small samples with a typical size of 1 × 1 cm very efficiently. The double‐bounce polarizer and the in situ pumped 3He SEOP (spin‐exchange optical pumping) neutron spin filter cell for analysing the polarization of the reflected neutron beam can be moved into the beam in seconds. The polarized flux of MARIA amounts to 5 × 107 n (s cm2)−1 at the sample position with a horizontally collimated beam of 3 mrad, a wavelength of λ = 4.5 Å and a wavelength resolution of Δλ/λ = 10%. In the non‐polarized mode a flux of 1.2 × 108 n (s cm2)−1 is achieved in this configuration. MARIA is also capable of grazing‐incidence small‐angle neutron scattering measurements, using a pinhole collimation with two four‐segment slits and an absorber that prevents the focusing of the elliptical guide in the vertical direction.
MARIA is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and biology. With the elliptical vertically focusing guide and a wavelength resolution of Δλ/λ = 10%, the non‐polarized flux at the sample position amounts to 1.2 × 108 n (s cm2)−1. Besides the polarized and non‐polarized reflectivity mode for specular and off‐specular reflectivity measurements, MARIA can also be used to carry out grazing‐incidence small‐angle neutron scattering investigations.
MARIA is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and biology. With the elliptical vertically focusing guide ...and a wavelength resolution of Δλ/λ = 10%, the non-polarized flux at the sample position amounts to 1.2 × 10
8
n (s cm
2
)
−1
. Besides the polarized and non-polarized reflectivity mode for specular and off-specular reflectivity measurements, MARIA can also be used to carry out grazing-incidence small-angle neutron scattering investigations.
MARIA (magnetism reflectometer with high incident angle) is a world class vertical sample reflectometer dedicated to the investigation of thin films in the fields of magnetism, soft matter and biology. The elliptical vertically focusing guide allows one to measure small samples with a typical size of 1 × 1 cm very efficiently. The double-bounce polarizer and the
in situ
pumped
3
He SEOP (spin-exchange optical pumping) neutron spin filter cell for analysing the polarization of the reflected neutron beam can be moved into the beam in seconds. The polarized flux of MARIA amounts to 5 × 10
7
n (s cm
2
)
−1
at the sample position with a horizontally collimated beam of 3 mrad, a wavelength of λ = 4.5 Å and a wavelength resolution of Δλ/λ = 10%. In the non-polarized mode a flux of 1.2 × 10
8
n (s cm
2
)
−1
is achieved in this configuration. MARIA is also capable of grazing-incidence small-angle neutron scattering measurements, using a pinhole collimation with two four-segment slits and an absorber that prevents the focusing of the elliptical guide in the vertical direction.
Exposure to altitude reduces oxygen supply to the central nervous system and may cause a variety of neuropsychological impairments. We investigated the relationship between certain cognitive ...functions and cardiovascular and respiratory variables during acute hypobaric hypoxia.
There were three groups of seven men who were each exposed to a 2-h altitude profile (AP) involving 30 min at each of the following simulated altitudes (m): AP1, 450-1500-3000; AP2, 450-1500-4500; Control 450-650-650. The neuropsychological tests included word fluency and three word-association tasks tapping processes of cognitive flexibility and emotion regulation. A lateralized tachistoscopic lexical decision task with high and low emotional target words was also administered to assess possible shifts in hemispheric superiorities for positive and negative affect.
No significant differences in word fluency, word association, or lateralized lexical decision performances were found, despite a significant oxygen desaturation and a drop in diastolic BP at 4500 m, indicating the beginning of central hypoxia in terms of a functional impairment of the vasomotor center.
During acute exposure to hypobaric hypoxia, selected cognitive and affective functions mediated by the frontal lobe were preserved. Functional hemispheric asymmetries for emotional processes remained unchanged.
Multiple camera systems are widely used for 3D-motion analysis. Due to increasing accuracies these camera systems gained interest in biomechanical research areas, where high precision measurements ...are desirable. In the current study different measurement systems were compared regarding their measurement accuracy. Translational and rotational accuracy measurements as well as the zero offset measurements of seven different measurement systems were performed using two reference devices and two different evaluation algorithms. All measurements were performed in the same room with constant temperature at the same laboratory. Equal positions were measured with the systems according to a standardized protocol. Measurement errors were determined and compared. The highest measurement errors were seen for a measurement system using active ultrasonic markers, followed by another active marker measurement system (infrared) having measurement errors up to several hundred micrometers. The highest accuracies were achieved by three stereo camera systems, using passive 2D marker points having errors typically below 20 mum. This study can help to better assess the results obtained with different measurement systems. With the focus on the measurement accuracy, only one aspect in the selection of a system was considered. Depending on the requirements of the user, other factors like measurement frequency, the maximum analyzable volume, the marker type or the costs are important factors as well.
A 5,000-year-old Yersinia pestis genome (RV 2039) is reconstructed from a hunter-fisher-gatherer (5300–5050 cal BP) buried at Riņņukalns, Latvia. RV 2039 is the first in a series of ancient strains ...that evolved shortly after the split of Y. pestis from its antecessor Y. pseudotuberculosis ∼7,000 years ago. The genomic and phylogenetic characteristics of RV 2039 are consistent with the hypothesis that this very early Y. pestis form was most likely less transmissible and maybe even less virulent than later strains. Our data do not support the scenario of a prehistoric pneumonic plague pandemic, as suggested previously for the Neolithic decline. The geographical and temporal distribution of the few prehistoric Y. pestis cases reported so far is more in agreement with single zoonotic events.
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•Yersinia pestis is discovered in a 5,000-year-old hunter-gatherer from Latvia•Y. pestis emerged ∼7,000 years ago at the beginning of the Neolithic•The infected individual might represent a case of septicemic plague due to zoonosis
Susat et al. reconstruct the genome of a 5,000-year-old Yersinia pestis strain detected in a hunter-gatherer from Latvia. The results show that the basal lineages evolved already at the beginning of the Neolithic and had presumably limited infection potential, suggesting isolated zoonotic events as causative triggers.
The energy levels of hydrogen-like atomic systems can be calculated with great precision. Starting from their quantum mechanical solution, they have been refined over the years to include the ...electron spin, the relativistic and quantum field effects, and tiny energy shifts related to the complex structure of the nucleus. These energy shifts caused by the nuclear structure are vastly magnified in hydrogen-like systems formed by a negative muon and a nucleus, so spectroscopy of these muonic ions can be used to investigate the nuclear structure with high precision. Here we present the measurement of two 2S-2P transitions in the muonic helium-4 ion that yields a precise determination of the root-mean-square charge radius of the α particle of 1.67824(83) femtometres. This determination from atomic spectroscopy is in excellent agreement with the value from electron scattering
, but a factor of 4.8 more precise, providing a benchmark for few-nucleon theories, lattice quantum chromodynamics and electron scattering. This agreement also constrains several beyond-standard-model theories proposed to explain the proton-radius puzzle
, in line with recent determinations of the proton charge radius
, and establishes spectroscopy of light muonic atoms and ions as a precise tool for studies of nuclear properties.
Epistemic planning: Perspectives on the special issue Belle, Vaishak; Bolander, Thomas; Herzig, Andreas ...
Artificial Intelligence,
March 2023, 2023-03-00, 2023-03, Volume:
316, Issue:
3/4 - Special Issue: Epistemic Planning
Journal Article, Publication
Peer reviewed
Epistemic planning is the enrichment of automated planning with epistemic notions such as knowledge and belief. In general, single-agent epistemic planning considers the following problem: given an ...agent's current state of knowledge, and a desirable state of knowledge, how does it get from one to the other? In multi-agent epistemic planning, the current and desirable states of knowledge might also refer to the states of knowledge of other agents, including higher-order knowledge like ensuring that agent A doesn't get to know that agent B knows P. Single-agent epistemic planning is of central importance in settings where agents need to be able to reason about their own lack of knowledge and, e.g., make plans of how to achieve the required knowledge. Multi-agent epistemic planning is essential for coordination and collaboration among multiple agents, where success can only be expected if agents are able to reason about the knowledge, uncertainty and capabilities of other agents. It is a relatively recent area of research involving several sub-areas of artificial intelligence, such as automated planning, decision-theoretic planning, epistemic logic, strategic reasoning and knowledge representation & reasoning. In order to achieve formalisms and systems for epistemic planning that are both expressive and practically efficient, it is necessary to combine state of the art from several such sub-areas of artificial intelligence that have so far been considered mostly in separation. Application areas of epistemic planning include mobile service robots, explaining planning, game playing, human-robot interaction and social robotics.
For this special issue of AIJ, we invited papers on theory, applications, and implemented systems of epistemic planning. In this document, we summarize the accepted papers whilst recapping the essentials of epistemic planning.
Laser spectroscopy of muonic deuterium Pohl, Randolf; Nez, François; Fernandes, Luis M. P. ...
Science,
08/2016, Volume:
353, Issue:
6300
Journal Article
Peer reviewed
Open access
The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius rd and the polarizability serve as important ...benchmarks for understanding the nuclear forces and structure. Muonic deuterium μd is the exotic atom formed by a deuteron and a negative muon μ⁻. We measured three 2S-2P transitions in μd and obtain rd = 2.12562(78) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value rd = 2.1424(21) fm. The μd value is also 3.5σ smaller than the rd value from electronic deuterium spectroscopy. The smaller rd, when combined with the electronic isotope shift, yields a "small" proton radius rp, similar to the one from muonic hydrogen, amplifying the proton radius puzzle.
Accurate knowledge of the charge and Zemach radii of the proton is essential, not only for understanding its structure but also as input for tests of bound-state quantum electrodynamics and its ...predictions for the energy levels of hydrogen. These radii may be extracted from the laser spectroscopy of muonic hydrogen (μp, that is, a proton orbited by a muon). We measured the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=0}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency in μp to be 54611.16(1.05) gigahertz (numbers in parentheses indicate one standard deviation of uncertainty) and reevaluated the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=1}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency, yielding 49881.35(65) gigahertz. From the measurements, we determined the Zemach radius, r Z = 1.082(37) femtometers, and the magnetic radius, r M = 0.87(6) femtometer, of the proton. We also extracted the charge radius, r E = 0.84087(39) femtometer, with an order of magnitude more precision than the 2010-CODATA value and at 7σ variance with respect to it, thus reinforcing the proton radius puzzle.
The hepatitis B virus (HBV) is one of the most widespread human pathogens known today, yet its origin and evolutionary history are still unclear and controversial. Here, we report the analysis of ...three ancient HBV genomes recovered from human skeletons found at three different archaeological sites in Germany. We reconstructed two Neolithic and one medieval HBV genome by
assembly from shotgun DNA sequencing data. Additionally, we observed HBV-specific peptides using paleo-proteomics. Our results demonstrated that HBV has circulated in the European population for at least 7000 years. The Neolithic HBV genomes show a high genomic similarity to each other. In a phylogenetic network, they do not group with any human-associated HBV genome and are most closely related to those infecting African non-human primates. The ancient viruses appear to represent distinct lineages that have no close relatives today and possibly went extinct. Our results reveal the great potential of ancient DNA from human skeletons in order to study the long-time evolution of blood borne viruses.
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