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1.
Phys Rev Lett ; 123(6): 066402, 2019 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-31491189

RESUMO

The momentum dependence of the nematic order parameter is an important ingredient in the microscopic description of iron-based high-temperature superconductors. While recent reports on FeSe indicate that the nematic order parameter changes sign between electron and hole bands, detailed knowledge is still missing for other compounds. Combining angle-resolved photoemission spectroscopy with uniaxial strain tuning, we measure the nematic band splitting in both FeSe and BaFe_{2}As_{2} without interference from either twinning or magnetic order. We find that the nematic order parameter exhibits the same momentum dependence in both compounds with a sign change between the Brillouin center and the corner. This suggests that the same microscopic mechanism drives the nematic order in spite of the very different phase diagrams.

2.
Phys Rev Lett ; 119(12): 126402, 2017 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-29341652

RESUMO

A ferromagnetic quantum critical point is thought not to exist in two- and three-dimensional metallic systems yet is realized in the Kondo lattice compound YbNi_{4}(P,As)_{2}, possibly due to its one-dimensionality. It is crucial to investigate the dimensionality of the Fermi surface of YbNi_{4}P_{2} experimentally, but common probes such as angle-resolved photoemission spectroscopy and quantum oscillation measurements are lacking. Here, we study the magnetic-field dependence of transport and thermodynamic properties of YbNi_{4}P_{2}. The Kondo effect is continuously suppressed, and additionally we identify nine Lifshitz transitions between 0.4 and 18 T. We analyze the transport coefficients in detail and identify the type of Lifshitz transitions as neck or void type to gain information on the Fermi surface of YbNi_{4}P_{2}. The large number of Lifshitz transitions observed within this small energy window is unprecedented and results from the particular flat renormalized band structure with strong 4f-electron character shaped by the Kondo lattice effect.

3.
J Phys Condens Matter ; 26(10): 106001, 2014 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-24553355

RESUMO

Physical properties of polycrystalline CeCrGe3 and LaCrGe3 have been investigated by x-ray absorption spectroscopy, magnetic susceptibility χ(T), isothermal magnetization M(H), electrical resistivity ρ(T), specific heat C(T) and thermoelectric power S(T) measurements. These compounds are found to crystallize in the hexagonal perovskite structure (space group P63/mmc), as previously reported. The ρ(T), χ(T) and C(T) data confirm the bulk ferromagnetic ordering of itinerant Cr moments in LaCrGe3 and CeCrGe3 with TC = 90 K and 70 K respectively. In addition, a weak anomaly is also observed near 3 K in the C(T) data of CeCrGe3. The T dependences of ρ and finite values of Sommerfeld coefficient γ obtained from the specific heat measurements confirm that both the compounds are of metallic character. Further, the T dependence of ρ of CeCrGe3 reflects a Kondo lattice behavior. An enhanced γ of 130 mJ mol(-1) K(-2) together with the Kondo lattice behavior inferred from the ρ(T) establish CeCrGe3 as a moderate heavy fermion compound with a quasi-particle mass renormalization factor of ∼45.


Assuntos
Césio/química , Cromo/química , Partículas Elementares , Germânio/química , Imãs , Modelos Químicos , Simulação por Computador , Impedância Elétrica , Condutividade Térmica
4.
Phys Rev Lett ; 110(25): 256403, 2013 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-23829750

RESUMO

We investigate the magnetic field dependent thermopower, thermal conductivity, resistivity, and Hall effect in the heavy fermion metal YbRh2Si2. In contrast to reports on thermodynamic measurements, we find in total three transitions at high fields, rather than a single one at 10 T. Using the Mott formula together with renormalized band calculations, we identify Lifshitz transitions as their origin. The predictions of the calculations show that all experimental results rely on an interplay of a smooth suppression of the Kondo effect and the spin splitting of the flat hybridized bands.

5.
Eur Arch Paediatr Dent ; 14(2): 89-95, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23559104

RESUMO

AIM: In paediatric dentistry, epinephrine may contribute to systemic and local side-effects. On the other hand it is necessary to provide good and safe local analgesia. Therefore, an articaine solution with reduced epinephrine concentration was tested in a clinical setting. METHODS: In a non-interventional clinical study, dental treatment was performed in children and adolescents (4-17 years). For local analgesia, articaine 4 % plus epinephrine 1:400,000 was used in the technique chosen by the dentist. Efficacy and tolerance as well as duration of soft tissue analgesia and side-effects were evaluated. RESULTS: 999 patients (50.5 % male, 49.5 % female) with a mean age of 7.9 (SD 2.34) years were treated. Two hundred seventy six patients (27.6 %) received sedation prior to treatment. The mean treatment time was 15 min (SD 10). In 93.5 % of cases, initial local analgesia was sufficient to perform the planned treatment. In 99 % of cases (n = 989) the planned treatment could be completed. A second injection was necessary in 6.5 % of cases. A mean duration of soft tissue analgesia of 2.19 h (SD 1.01) was seen. Slight side-effects occurred in 3.1 % of subjects. CONCLUSIONS: Due to high efficacy, tolerance and safety, the articaine 4 % solution with the reduced epinephrine concentration (1:400,000) was a safe and suitable drug for paediatric routine treatment.


Assuntos
Carticaína , Odontopediatria , Anestesia Dentária , Anestésicos Locais/administração & dosagem , Carticaína/administração & dosagem , Criança , Método Duplo-Cego , Epinefrina , Humanos , Vasoconstritores
6.
J Exp Biol ; 195(1): 147-67, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9317521

RESUMO

We describe the functional morphology of the singing apparatus of the cricket. There are three main functional sections of song mechanics, which partly overlap: (1) preparation for singing (lifting of the wings) and the reverse process (lowering of the wings at the end of the song); (2) singing movements (closing and opening of the wings); and (3) movements that adjust the pressure of the plectrum on the file (engagement force). In the case of song preparation, the mesotergum + first axillaries + second axillaries + wings form a functional unit. This unit is moved around a transverse hinge axis, which runs through both fulcrum joints. The muscles suitable for wing lifting are the prothoracic furca muscle and the mesothoracic tegula muscle. Those suitable for wing lowering are the prothoracic dorsolongitudinal muscles and the mesothoracic axillary 4, subalar and furca muscles. Lifting and lowering of the wings are superimposed by bistable mechanisms, which are adjustable (mesothoracic medial dorsolongitudinal muscles). In the case of closing movements (dorsoventral muscles) and opening movements (basalar and subalar muscles), the mesotergum and the wings are moved relative to each other, as for flight movements, but with the wings remaining folded back. The mesotergum is rotated down (closing) and up (opening) around a transverse hinge axis that runs through the caudal joints between the mesotergum and postnota. The path of movement of the wing and its sound-generating structure (i.e. plectrum or file respectively) is determined by an obliquely oriented hinge axis between the mesotergum and first axillary. During opening and closing, the lifted singing position of the wings is stabilized by the medial dorsolongitudinal muscles. We also discuss the role of other muscles that affect singing movements. The third axillary (and its muscle) and the postnotum [and its muscles, the furca muscle and the lateral (short) dorsolongitudinal muscle] are the main elements in the system that adjusts the engagement force of the wings. When left axillary 3 muscle contracts, the medial part of the left third axillary is rotated caudally (in its vertical hinge joint with the first median plate) against the anal part of the wing. The anal part is bent and rotated upwards, increasing the pressure of the left plectrum against the right file. Conversely, the right axillary 3 muscle, which moves the file away from the plectrum, is able to reduce the pressure. The left furca muscle (the antagonist of left axillary 3 muscle) and the left lateral (short) dorsolongitudinal muscle (the 'synergist' of left axillary 3 muscle), and the corresponding muscles on the right side (which have opposite functions), allow a large range of different engagement forces. The results are compared with the work of other authors on the functional morphology of this system and with the results of electrophysiological investigations. New aspects of the evolution of the singing mechanisms are discussed.

7.
Genomics ; 11(4): 948-55, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1686021

RESUMO

Employing the flow-sorted chromosome 20-specific DNA library LL20NS01, we isolated seven novel unique poly- and monomorphic DNA markers specific to human chromosome 20. Initially, 201 phage clones were analyzed regarding insert size and repetitivity. By testing 14 single- and low-copy number clones for their ability to detect RFLPs, three polymorphisms were revealed by two probes, pFMS22-1.4 [D20S22] and pFMS76 [D20S23]. Seven of twenty probes (35%) were assigned to chromosome 20 using a somatic cell hybrid DNA panel. Five of them were regionally mapped by in situ hybridization. Three DNA markers, pFMS51 [D20S29], pFMS76 [D20S23], and pFMS106 [D20S30], were assigned to 20p11.2-p12, and two markers, pFMS22-1.4 [D20S22] and pFMS135 [D20S31], to 20q12-q13.3. Our new chromosome 20-specific DNA markers should be useful for the molecular characterization of this rather underpopulated human chromosome.


Assuntos
Cromossomos Humanos Par 20 , Marcadores Genéticos , Bacteriófagos/genética , Southern Blotting , Bandeamento Cromossômico , Mapeamento Cromossômico , Clonagem Molecular , Feminino , Citometria de Fluxo , Biblioteca Gênica , Humanos , Células Híbridas , Masculino , Linhagem , Polimorfismo de Fragmento de Restrição
8.
J Gerontol ; 41(4): 481-5, 1986 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-3722732

RESUMO

Conflicting results have been reported for the lifetime distribution of personal memories. To resolve the discrepancy, two age groups were asked to respond to cue words by supplying event associations, and to date the remembered events using either the standard or a serial procedure. Memory retrieval times, dating times, and the frequencies of elicited memories, were compared across the four quarters of the life span. The 70-year-olds took twice as long to respond, and twice as long to supply dates, as the 20-year-olds. Age interacted with period of life, in dating time, but not with the dating method on any measure. The serial dating method halved the time required by the standard method but, as predicted, distorted the lifetime frequency pattern. With serial dating, earlier memories were more rapidly dated and more numerous than with the standard procedure. The effects are ascribed to the activation of temporal markers in both age groups.


Assuntos
Envelhecimento , Acontecimentos que Mudam a Vida , Memória , Adolescente , Adulto , Idoso , Humanos , Pessoa de Meia-Idade , Tempo
11.
Anat Anz ; 143(2): 199-204, 1978.
Artigo em Alemão | MEDLINE | ID: mdl-646131

RESUMO

There were laid sections in a difference of 1 cm across the condyli femoris of 5 human formalin-fixed femora and was looked for the curvature of the areas of joints at their marks. In comparing with literature was to be seen that corresponding dats failed at the orientation of the bone. Model conceptions used in case of compensation can't be accepted. Exact calculations of the three-dimensional curvature of surface are presumed for taking into account the mechanism of transfer of forces in the knee joint.


Assuntos
Fenômenos Biomecânicos , Articulação do Joelho/fisiologia , Idoso , Fêmur/fisiologia , Humanos , Movimento , Esforço Físico , Rotação
12.
Zahn Mund Kieferheilkd Zentralbl ; 66(4): 389-404, 1978.
Artigo em Alemão | MEDLINE | ID: mdl-151426

RESUMO

From a compilation of all investigative results it is apparent that there are only minor differences in edge-strength between the AP preparations and VH 67 grade. Showing the best values within this particular group is the AP 3 grade. Its use as a filling material may be expected to yield the best results as regards durability. In contrast, the results obtainded for the VH 50 grade material cannot be regarded as satisfying the requirements of a dental amalgam. A marked tendency toward creeping and high rates of corrosion result in the edge-strength of this material being reduced to an unacceptable level.


Assuntos
Amálgama Dentário/normas , Corrosão , Análise do Estresse Dentário , Dureza , Prata , Estanho
13.
Anat Anz ; 142(5): 512-8, 1977.
Artigo em Alemão | MEDLINE | ID: mdl-607818

RESUMO

The authors experiments (n = 50) and calculation (n = 1000) with human hollow bone revealed physical and chemical data which were compared. It was shown that the physical and chemical properties are different in the diaphysis and epiphysis. These regularities are the consequence of the physical and chemical inhomogenities. These findings can be explained as a mechanism of protection.


Assuntos
Fenômenos Biomecânicos , Osso e Ossos/fisiologia , Osso e Ossos/metabolismo , Cálcio/metabolismo , Citratos/metabolismo , Elasticidade , Humanos , Lactatos/metabolismo , Fósforo/metabolismo
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