1,479 research outputs found
Collective Spin Modes in Superconducting Double Layers
We investigate a double layer system with tight-binding hopping, intra-layer
and inter-layer interactions, as well as a Josephson like coupling. We find
that an antiferromagnetic spin polarization induces additional spin-triplet
pairing (with ) to the singlet order parameter. This causes an undamped
collective mode in the superconducting state below the particle-hole threshold,
which is interpreted as a Goldstone excitation.Comment: 7 pages, latex, 2 postscript figure
Interactive Videos vs. Hypertext Documents – The Effect on Learning Quality and Time Effort when Acquiring Procedural Knowledge
The use of information systems and the rise of new learning concepts have changed the way individuals are acquiring knowledge in organizational, educational and private contexts. Recently, video tutorials have become a widely-used instrument for learning and successful platforms emerged, offering massive open online courses based on video content. With the existence of different learning technologies the question arises: How these media formats affect the learning performance of individuals? We introduce interactive videos as a new media format and compare this technology to hypertext documents in an educational context. Our results from an experiment with 130 participants reveal that the learning quality can be significantly increased when interactive videos are used to acquire procedural knowledge. However, we did not observe any effect on time effort
Extending MIEZE spectroscopy towards thermal wavelengths
We propose a Modulation of intensity with zero effort (MIEZE) set-up for
high-resolution neutron spectroscopy at momentum transfers up to
3\AA,energy transfers up to ~ 20 meV, and an energy resolution in the
eV-range using both thermal and cold neutrons. MIEZE has two prominent
advantages compared to classical neutron spin-echo. The first one is the
possibility to investigate spin-depolarizing samples or samples in strong
magnetic fields without loss of signal amplitude and intensity. This allows for
the study of spin fluctuations in ferromagnets, and facilitates the study of
samples with strong spin-incoherent scattering. The second advantage is that
multi-analyzer setups can be implemented with comparatively small effort. The
use of thermal neutrons increases the range of validity of the spin-echo
approximation towards shorter spin-echo times. In turn, the thermal MIEZE
option for greater ranges (TIGER) closes the gap between classical neutron
spin-echo spectroscopy and conventional high-resolution neutron spectroscopy
techniques such as triple-axis, time-of-flight, and back-scattering. To
illustrate the feasibility of TIGER we present the details of an implementation
at the beamline RESEDA at FRM II by means of an additional velocity selector,
polarizer and analyzer
Socio‐economic impact classification of alien taxa (SEICAT)
1 Many alien taxa are known to cause socio‐economic impacts by affecting the different constituents of human well‐being (security; material and non‐material assets; health; social, spiritual and cultural relations; freedom of choice and action). Attempts to quantify socio‐economic impacts in monetary terms are unlikely to provide a useful basis for evaluating and comparing impacts of alien taxa because they are notoriously difficult to measure and important aspects of human well‐being are ignored.
2 Here, we propose a novel standardised method for classifying alien taxa in terms of the magnitude of their impacts on human well‐being, based on the capability approach from welfare economics. The core characteristic of this approach is that it uses changes in peoples' activities as a common metric for evaluating impacts on well‐being.
2 Impacts are assigned to one of five levels, from Minimal Concern to Massive, according to semi‐quantitative scenarios that describe the severity of the impacts. Taxa are then classified according to the highest level of deleterious impact that they have been recorded to cause on any constituent of human well‐being. The scheme also includes categories for taxa that are not evaluated, have no alien population, or are data deficient, and a method for assigning uncertainty to all the classifications. To demonstrate the utility of the system, we classified impacts of amphibians globally. These showed a variety of impacts on human well‐being, with the cane toad (Rhinella marina) scoring Major impacts. For most species, however, no studies reporting impacts on human well‐being were found, i.e. these species were data deficient.
2 The classification provides a consistent procedure for translating the broad range of measures and types of impact into ranked levels of socio‐economic impact, assigns alien taxa on the basis of the best available evidence of their documented deleterious impacts, and is applicable across taxa and at a range of spatial scales. The system was designed to align closely with the Environmental Impact Classification for Alien Taxa (EICAT) and the Red List, both of which have been adopted by the International Union of Nature Conservation (IUCN), and could therefore be readily integrated into international practices and policies
Complete phase retrieval of photoelectron wavepackets
Coherent, broadband pulses of extreme ultraviolet (XUV) light provide a new
and exciting tool for exploring attosecond electron dynamics. Using
photoelectron streaking, interferometric spectrograms can be generated that
contain a wealth of information about the phase properties of the
photoionization process. If properly retrieved, this phase information reveals
attosecond dynamics during photoelectron emission such as multielectron
dynamics and resonance processes. However, until now, the full retrieval of the
continuous electron wavepacket phase from isolated attosecond pulses has
remained challenging. Here, after elucidating key approximations and
limitations that hinder one from extracting the coherent electron wavepacket
dynamics using available retrieval algorithms, we present a new method called
Absolute Complex Dipole transmission matrix element reConstruction (ACDC). We
apply the ACDC method to experimental spectrograms to resolve the phase and
group delay difference between photoelectrons emitted from Ne and Ar. Our
results reveal subtle dynamics in this group delay difference of photoelectrons
emitted form Ar. These group delay dynamics were not resolvable with prior
methods that were only able to extract phase information at discrete energy
levels, emphasizing the importance of a complete and continuous phase retrieval
technique such as ACDC. Here we also make this new ACDC retrieval algorithm
available with appropriate citation in return
Age Affects Quantity but Not Quality of Antibody Responses after Vaccination with an Inactivated Flavivirus Vaccine against Tick-Borne Encephalitis
The impairment of immune functions in the elderly (immunosenescence) results in post-vaccination antibody titers that are significantly lower than in young individuals. It is, however, a controversial question whether also the quality of antibodies declines with age. In this study, we have therefore investigated the age-dependence of functional characteristics of antibody responses induced by vaccination with an inactivated flavivirus vaccine against tick-borne encephalitis (TBE). For this purpose, we quantified TBE virus-specific IgG and neutralizing antibody titers in post-vaccination sera from groups of young and elderly healthy adults and determined antibody avidities and NT/ELISA titer ratios (functional activity). In contrast to the quantitative impairment of antibody production in the elderly, we found no age-related differences in the avidity and functional activity of antibodies induced by vaccination, which also appeared to be independent of the age at primary immunization. There was no correlation between antibody avidity and NT/ELISA ratios suggesting that additional factors affect the quality of polyclonal responses, independent of age. Our work indicates that healthy elderly people are able to produce antibodies in response to vaccination with similar avidity and functional activity as young individuals, albeit at lower titers
Visual and Electrosensory Circuits of the Diencephalon in Mormyrids
Mormyrids are one of two groups of teleost fishes known to have evolved electroreception, and the concomitant neuroanatomical changes have confounded the interpretation of many of their brain areas in a comparative context, e.g., the diencephalon, where different sensory systems are processed and relayed. Recently, cerebellar and retinal connections of the diencephalon in mormyrids were reported. The present study reports on the telencephalic and tectal connections, specifically in Gnathonemus petersii, as these data are critical for an accurate interpretation of diencephalic nuclei in teleosts. Injections of horseradish peroxidase into the telencephalon retrogradely labeled neurons ipsilaterally in various thalamic, preglomerular, and tuberal nuclei, the nucleus of the locus coeruleus (also contralaterally), the superior raphe, and portions of the nucleus lateralis valvulae. Telencephalic injections anterogradely labeled the dorsal preglomerular and the dorsal tegmental nuclei bilaterally.
Injections into the optic tectum retrogradely labeled neurons bilaterally in the central zone of area dorsalis telencephali and ipsilaterally in the torus longitudinalis, various thalamic, pretectal, and tegmental nuclei, some nuclei in the torus semicircularis, the nucleus of the locus coeruleus, the nucleus isthmi and the superior reticular formation, basal cells in the ipsilateral valvula cerebelli, and eurydendroid cells in the contralateral lobe C4 of the corpus cerebelli. Weaker contralateral projections were also observed to arise from the ventromedial thalamus and various pretectal and tegmental nuclei, and from the locus coeruleus and superior reticular formation. Tectal injections anterogradely labeled various pretectal nuclei bilaterally, as well as ipsilaterally the dorsal preglomerular and dorsal posterior thalamic nuclei, some nuclei in the torus semicircularis, the dorsal tegmental nucleus, nucleus isthmi, and, again bilaterally, the superior reticular formation.
A comparison of retinal, cerebellar, tectal, and telencephalic connections in Gnathonemus with those in nonelectrosensory teleosts reveals several points: (1 the visual area of the diencephalon is highly reduced in Gnathonemus, (2) the interconnections between the preglomerular area and telencephalon in Gnathonemus are unusually well developed compared to those in other teleosts, and (3) two of the three corpopetal diencephalic nuclei are homologues of the central and dorsal periventricular pretectum in other teleosts. The third is a subdivision of the preglomerular area, rather than an accessory optic or pretectal nucleus, and is related to electroreception. The preglomerulo-cerebellar connections in Gnathonemus are therefore interpreted as uniquely derived characters for mormyrids
- …