1,616 research outputs found
Crossover from Single-Ion to Coherent Non-Fermi Liquid Behavior in CeLaNiGe
We report specific heat and magneto-resistance studies on the compound
CeLaNiGe for various concentrations over the entire
stoichiometric range. Our data reveal single-ion scaling with Ce-concentration
between and 0.95. Furthermore, CeNiGe turns out to have
the largest ever recorded value of the electronic specific heat 5.5 J at K which was found in Cerium
f-electron lattice systems. In the doped samples increases
logarithmically in the temperature range between 3 K and 50 mK typical for
non-Fermi liquid (nFl) behavior, while exhibits a Kondo-like minimum
around 30 K, followed by a single-ion local nFl behavior. In contrast to this,
CeNiGe flattens out in below 300 mK and displays a
pronounced maximum in the resistivity curve at 1.5 K indicating a coherent
heavy fermion groundstate. These properties render the compound
CeLaNiGe a unique system on the borderline between
Fermi liquid and nFl physics.Comment: 2 pages, 3 figures, SCES0
Possible canted antiferromagnetism in UCuSn
We report on the new compound UCuSn which crystallizes in the
tetragonal structure \emph{I}4/\emph{mcm} with lattice parameters and . This compound is isotyp to the
ferromagnetic systems RECuSn (RE = Ce, Pr, Nd) with Curie
temperatures = 5.5 K, 10.5 K and 15 K, respectively.
UCuSn exhibits an uncommon magnetic behavior resulting in three
different electronic phase transitions. Below 105 K the sample undergoes a
valence transition accompanied by an entropy change of 0.5 Rln2. At 32 K a
small hump in the specific heat and a flattening out in the susceptibility
curve probably indicate the onset of helical spin order. To lower temperatures
a second transition to antiferromagnetic ordering occurs which develops a small
ferromagnetic contribution on lowering the temperature further. These results
are strongly hinting for canted antiferromagnetism in UCuSn.Comment: 2 pages, 3 figures, SCES0
Unusual Non-Fermi Liquid Behavior of CeLaNiGe Analyzed in a Single Impurity Anderson Model with Crystal Field Effects
CeNiGe exhibits unusual non-Fermi liquid behavior with the largest
ever recorded value of the electronic specific heat
JKmol without showing any evidence of magnetic order. Specific
heat measurements show that the logarithmic increase of the Sommerfeld
coefficient flattens off below 200 mK. In marked contrast, the local
susceptibility levels off well above 200 mK and already becomes
constant below 1 K. Furthermore, the entropy reaches 2ln2 below 20 K
corresponding to a four level system. An analysis of and was
performed in terms of an single impurity Anderson model with
additional crystal electric field (CEF) splitting. Numerical renormalization
group calculations point to a possible consistent description of the different
low temperature scales in and stemming from the
interplay of Kondo effect and crystal field splitting.Comment: 2 pages, 2 figure
Thermoelectric properties of Zn_5Sb_4In_(2-δ)(δ=0.15)
The polymorphic intermetallic compound Zn_5Sb_4In_(2−δ) (δ = 0.15(3)) shows promising thermoelectric properties at low temperatures, approaching a figure of merit ZT of 0.3 at 300 K. However, thermopower and electrical resistivity changes discontinuously at around 220 K. Measurement of the specific heat locates the previously unknown temperature of the order-disorder phase transition at around 180 K. Investigation of the charge carrier concentration and mobility by Hall measurements and infrared reflection spectroscopy indicate a mixed conduction behavior and the activation of charge carriers at temperatures above 220 K. Zn_5Sb_4In_(2−δ) has a low thermal stability, and at temperatures above 470 K samples decompose into a mixture of Zn, InSb, and Zn_4Sb_3
Do female rainbow kribs choose males on the basis of their apparent aggression and boldness? A non-correlational mate choice study
Abstract: Consistent between-individual differences in behaviour, known as personality differences, are heritable and have consequences for individual survival and reproductive success. Therefore, it is likely that personality differences are not just under natural but also under sexual selection. Indeed, the recently developed idea that individuals choose their mate based on its personality finds empirical support. However, most studies on mate choice based on personality traits are correlative pioneering work and there is a paucity of experimental studies that test for causality by disentangling personality measures from other, potentially correlated traits that may be important during mate choice. Here, we tested female preference for the apparent level and consistency of either male aggression (measured as mean distance of approach towards an animated opponent, manipulated by locating males at a fixed distance) or male boldness (measured as activity under a simulated predation threat, manipulated using a gradient in ambient water temperature) in a bi-parental West African cichlid, Pelvicachromis pulcher. Females could observe the apparent behaviour of paired stimulus males and were allowed to choose between the two stimulus males in a subsequent choice test. We found no direct effect of male apparent aggression/boldness on female choice, but an indirect effect such that female preference for the apparently bold male increased with increasing within-male pair contrast in their apparent level of boldness. Our results indicate females consider male boldness per se during mate choice, suggesting male boldness is sexually selected in our study species. Significance statement: Ever since Darwin introduced the concept of sexual selection, female choice has been studied extensively. However, the hypothesis that consistent between-individual differences in behaviour (known as personality differences) affect mate choice is relatively new. Correlative studies support this idea but provide only suggestive evidence. Here, we used behavioural manipulations in order to disentangle male behaviour from other, potentially correlated male traits, allowing us to test for causality between female choice and personality differences in male aggression and boldness (both in level and consistency of behaviour) in a bi-parental cichlid. We found no overall female preference for male apparent behaviour, but female preference for the bold-appearing male increased with increasing between-male contrast in apparent boldness. Our results indicate a causal link between female choice and male boldness. In future, behavioural manipulations using a temperature gradient could provide further valuable insights
Evolution of single-ion crystal field and Kondo features in CeLaNiCuGe
Starting with the heavy fermion compound CeNiGe, the substitution of
nickel by copper leads to a dominance of the RKKY interaction in competition
with the Kondo and crystal field interaction. Consequently, this results in an
antiferromagnetic phase transition in CeNiCuGe for ,
which is, however, not fully completed up to a Cu-concentration of . To
study the influence of single-ion effects on the AFM ordering by shielding the
-moments, we analyzed the spin diluted substitution series
LaCeNiCuGe by magnetic susceptibility
and specific heat measurements. For small Cu-amounts the data
reveal single-ion scaling with regard to the Ce-concentration, while for larger
Cu-concentrations the AFM transition (encountered in the
CeNiCuGe series) is found to be completely depressed.
Calculation of the entropy reveal that the Kondo-effect still shields the
4-moments of the Ce-ions in CeNiCuGe.Comment: 4 pages, 3 figures, conference SCES0
Dimensions and clusters of aesthetic emotions: A semantic profile analysis
Aesthetic emotions are elicited by different sensory impressions generated by music, visual arts, literature, theater, film, or nature scenes. Recently, the AESTHEMOS scale has been developed to facilitate the empirical assessment of such emotions. In this article we report a semantic profile analysis of aesthetic emotion terms that had been used for the development of this scale, using the GRID approach. This method consists of obtaining ratings of emotion terms on a set of meaning facets (features) which represent five components of the emotion process (appraisal, bodily reactions, action tendencies, expression, and feelings). The aims here were (a) to determine the dimensionality of the GRID features when applied to aesthetic emotions and compare it to published results for emotion terms in general, and (b) to examine the internal organization of the domain of aesthetic emotion terms in order to identify salient clusters of these items based on the similarity of their feature profiles on the GRID. Exploratory Principal Component Analyses suggest a four-dimensional structure of the semantic space consisting of valence, power, arousal, and novelty, converging with earlier GRID studies on large sets of standard emotion terms. Using cluster analyses, 15 clusters of aesthetic emotion terms with similar GRID feature profiles were identified, revealing the internal organization of the aesthetic emotion terms domain and meaningful subgroups of aesthetic emotions. While replication for further languages is required, these findings provide a solid basis for further research and methodological development in the realm of aesthetic emotions
Recognizing Emotions in a Foreign Language
Expressions of basic emotions (joy, sadness, anger, fear, disgust) can be recognized pan-culturally from the face and it is assumed that these emotions can be recognized from a speaker's voice, regardless of an individual's culture or linguistic ability. Here, we compared how monolingual speakers of Argentine Spanish recognize basic emotions from pseudo-utterances ("nonsense speech") produced in their native language and in three foreign languages (English, German, Arabic). Results indicated that vocal expressions of basic emotions could be decoded in each language condition at accuracy levels exceeding chance, although Spanish listeners performed significantly better overall in their native language ("in-group advantage"). Our findings argue that the ability to understand vocally-expressed emotions in speech is partly independent of linguistic ability and involves universal principles, although this ability is also shaped by linguistic and cultural variables
Crystal field studies on the heavy fermion compound CeNiCuGe
Substitution of nickel by copper in the heavy fermion system
CeNiCuGe alters the local crystal field environment of the
Ce-ions. This leads to a quantum phase transition near ,
which is not only driven by the competition between Kondo effect and RKKY
interaction, but also by a reduction of an effectively fourfold to a twofold
degenerate crystal field ground state. To study the consequences of a changing
crystal field in CeNiCuGe on its Kondo properties, inelastic neutron
scattering (INS) experiments were performed. Two well-defined crystal field
transitions were observed in the energy-loss spectra at 4 K. The crystal field
level scheme determined by neutron spectroscopy is compared with results from
specific heat measurements.Comment: 4 pages, 3 figures, conference SCES0
Hadron formation and attenuation in deep inelastic lepton scattering off nuclei
We investigate hadron formation in deep inelastic lepton scattering on N, Kr
and Xe nuclei in the kinematic regime of the HERMES experiment. The elementary
electron-nucleon interaction is described within the event generator PYTHIA
while a full coupled-channel treatment of the final state interactions is
included by means of a BUU transport model. We find a good agreement with the
measured charged hadron multiplicity ratio for N and Kr targets by
accounting for the deceleration and absorption of the primarily produced
particles as well as for the creation of secondary hadrons in the final state
interactions.Comment: 13 pages, 5 figures; revised and extended version, accepted for
publication in Phys. Lett.
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