1,486 research outputs found
Kurt Schwitters' An Anna Blume and the gendered politics of printmaking in Weimar Germany
Prominent German modernist Kurt Schwitters indulged in fragmented and nonsense aspects of art for most of his career. While Schwitters' collages and assemblages are his best-known works, what is missing from current scholarship is a comprehensive investigation of Schwitters' prints within the socio-historical context of the Weimar Republic. This thesis demonstrates how the print medium can add to our understanding of Schwitters' artistic career. The first chapter explores Schwitters as a printmaker, and how he aligned printmaking techniques with his artistic project titled "Merz." The second and third chapters address the apparent connection between Schwitters' print Komposition mit Kopf im Linksprofil, his renowned poem An Anna Blume, and numerous other works he created between 1919 and 1924. By bringing Schwitters' prints to the foreground, even his secondary works shed interesting light on modern artistic printmaking, Merz theory, and the politics of gender during the Weimar Republic. Largely due to the consequences of the First World War, this thesis argues that the graphic arts played an inevitable role in the history of Schwitters' artistic career
The role of carbon for superconductivity in MgCNi from specific heat
The influence of carbon deficiency on superconductivity of MgCNi is
investigated by specific heat measurements in the normal and superconducting
state. In order to perform a detailed analysis of the normal state specific
heat, a computer code is developed which allows for an instantaneous estimate
of the main features of the lattice dynamics. By analyzing the evolution of the
lattice vibrations within the series and simultaneously considering the visible
mass enhancement, the loss in the electron-phonon coupling can be attributed to
significant changes of the prominent Ni vibrations. The present data well
supports the recently established picture of strong electron-phonon coupling
and ferromagnetic spin fluctuations in this compound.Comment: 4 pages, latex, corrections to the text, one reference added, one
figure correcte
Temperature dependence of iron local magnetic moment in phase-separated superconducting chalcogenide
We have studied local magnetic moment and electronic phase separation in
superconducting KFeSe by x-ray emission and absorption
spectroscopy. Detailed temperature dependent measurements at the Fe K-edge have
revealed coexisting electronic phases and their correlation with the transport
properties. By cooling down, the local magnetic moment of Fe shows a sharp drop
across the superconducting transition temperature (T) and the coexisting
phases exchange spectral weights with the low spin state gaining intensity at
the expense of the higher spin state. After annealing the sample across the
iron-vacancy order temperature, the system does not recover the initial state
and the spectral weight anomaly at T as well as superconductivity
disappear. The results clearly underline that the coexistence of the low spin
and high spin phases and the transitions between them provide unusual magnetic
fluctuations and have a fundamental role in the superconducting mechanism of
electronically inhomogeneous KFeSe system.Comment: 6 pages, 5 figure
Pressure effects in the triangular layered cobaltites NaxCoO2
We have measured transport properties as a function of temperature and
pressure up to 30GPa in the NaxCoO2 system. For the x=0.5 sample the transition
temperature at 53K increases with pressure, while paradoxically the sample
passes from an insulating to a metallic ground state. A similar transition is
observed in the x=0.31 sample under pressure. Compression on the x=0.75 sample
transforms the sample from a metallic to an insulating state. We discuss our
results in terms of interactions between band structure effects and Na+ order.Comment: 18 pages, 5 figure
Evidences of a consolute critical point in the Phase Separation regime of La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single crystals
We report on DC and pulsed electric field sensitivity of the resistance of
mixed valent Mn oxide based La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single
crystals as a function of temperature. The low temperature regime of the
resistivity is highly current and voltage dependent. An irreversible transition
from high (HR) to a low resistivity (LR) is obtained upon the increase of the
electric field up to a temperature dependent critical value (V_c). The
current-voltage characteristics in the LR regime as well as the lack of a
variation in the magnetization response when V_c is reached indicate the
formation of a non-single connected filamentary conducting path. The
temperature dependence of V_c indicates the existence of a consolute point
where the conducting and insulating phases produce a critical behavior as a
consequence of their separation.Comment: 5 pages, 6 figures, corresponding author: C. Acha ([email protected]
Structural transformations and disordering in zirconolite (CaZrTi2O7) at high pressure
There is interest in identifying novel materials for use in radioactive waste applications and studying their behavior under high pressure conditions. The mineral zirconolite (CaZrTi2O7) exists naturally in trace amounts in diamond-bearing deep-seated metamorphic/igneous environments, and it is also identified as a potential ceramic phase for radionuclide sequestration. However, it has been shown to undergo radiation-induced metamictization resulting in amorphous forms. In this study we probed the high pressure structural properties of this pyrochlore-like structure to study its phase transformations and possible amorphization behavior. Combined synchrotron X-ray diffraction and Raman spectroscopy studies reveal a series of high pressure phase transformations. Starting from the ambient pressure monoclinic structure, an intermediate phase with P21/m symmetry is produced above 15.6 GPa via a first order transformation resulting in a wide coexistence range. Upon compression to above 56 GPa a disordered metastable phase III with a cotunnite-related structure appears that is recoverable to ambient conditions. We examine the similarity between the zirconolite behavior and the structural evolution of analogous pyrochlore systems under pressure.<br/
Synchrotron X-ray Diffraction Study of BaFe2As2 and CaFe2As2 at High Pressures up to 56 GPa: Ambient and Low-Temperatures Down to 33 K
We report high pressure powder synchrotron x-ray diffraction studies on
MFe2As2 (M=Ba, Ca) over a range of temperatures and pressures up to about 56
GPa using a membrane diamond anvil cell. A phase transition to a collapsed
tetragonal phase is observed in both compounds upon compression. However, at
300 (33) K in the Ba-compound the transition occurs at 26 (29) GPa, which is a
much higher pressure than 1.7 (0.3) GPa at 300 (40) K in the Ca-compound, due
to its larger volume. It is important to note that the transition in both
compounds occurs when they are compressed to almost the same value of the unit
cell volume and attain similar ct/at ratios. We also show that the FeAs4
tetrahedra are much less compressible and more distorted in the collapsed
tetragonal phase than their nearly regular shape in the ambient pressure phase.
We present a detailed analysis of the pressure dependence of the structures as
well as equation of states in these important BaFe2As2 and CaFe2As2 compounds.Comment: 26 pages, 12 figure
Surgical and postsurgical wound care in hidradenitis suppurativa
Hidradenitis suppurativa (HS) is a chronic inflammatory disorder. Several medical treatments, with varying degree of efficacy, have been developed. However, in most cases of advanced (HS), the definitive treatment option is often represented by surgical excisions. Surgical techniques, reconstructive approach, and local wound care should be accurately designed in order to obtain the best result. In this letter, we analyzed the possible surgical treatments and local wound care. A literature review was performed on the various surgical treatments, reconstructive techniques, and local wound care. Surgical treatment is a common therapeutic modality for HS. Different surgical reconstructive techniques and postsurgical wound care approaches are described for the management of HS patients. There were few high-quality evidence-based studies evaluating the surgical management of HS. Many disparate HS severity scores were used in these studies making comparison between them difficult. Nonetheless, research into different surgical approaches and wound care management has increased substantially in the past decade and has given patients more surgical therapeutic strategies. The description of the best combinations and timing of surgery, wound care and medical therapies, will be a matter of future research for the definition of the optimal management of HS patient
Hidradenitis suppurativa: Surgical and postsurgical management
Background: Hidradenitis suppurativa (HS) is a chronic inflammatory disorder. Several medical treatments, with varying degrees of efficacy, have been developed. However, in most cases of advanced HS, the definitive treatment option is often represented by surgical excisions. Objective: Surgical techniques, reconstructive approach, and local wound care should be accurately designed in order to obtain the best result. In this review we analyze the possible surgical treatments and local wound care. Methods: A MEDLINE search was performed on the various surgical treatments, reconstructive techniques, and local wound care. Results: Surgical treatment is a common therapeutic modality for HS. Different surgical reconstructive techniques and post-surgical wound care approaches are described for the management of HS patients. Conclusions: There were few high-quality evidence-based studies evaluating the surgical management of HS. Many disparate HS severity scores were used in these studies, making comparisons between them difficult. Nonetheless, research on different surgical approaches and wound care management has increased substantially in the past decade and it has given patients more surgical therapeutic strategies. The description of the best combinations and timing of surgery, wound care, and medical therapies will be a matter of future research for the definition of the optimal management of the HS patient
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