The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors.

In the underdoped copper-oxides, high-temperature superconductivity condenses from a nonconventional metallic "pseudogap" phase that exhibits a variety of non-Fermi liquid properties. Recently, it has become clear that a charge density wave (CDW) phase exists within the pseudogap regime. This CDW coexists and competes with superconductivity (SC) below the transition temperature Tc, suggesting that these two orders are intimately related. Here we show that the condensation of the superfluid from this unconventional precursor is reflected in deviations from the predictions of BSC theory regarding the recombination rate of quasiparticles. We report a detailed investigation of the quasiparticle (QP) recombination lifetime, τqp, as a function of temperature and magnetic field in underdoped HgBa2CuO(4+δ) (Hg-1201) and YBa2Cu3O(6+x) (YBCO) single crystals by ultrafast time-resolved reflectivity. We find that τqp(T) exhibits a local maximum in a small temperature window near Tc that is prominent in underdoped samples with coexisting charge order and vanishes with application of a small magnetic field. We explain this unusual, non-BCS behavior by positing that Tc marks a transition from phase-fluctuating SC/CDW composite order above to a SC/CDW condensate below. Our results suggest that the superfluid in underdoped cuprates is a condensate of coherently-mixed particle-particle and particle-hole pairs.

Commensurate antiferromagnetic excitations as a signature of the pseudogap in the tetragonal high-Tc cuprate HgBa2CuO(4+δ).

Antiferromagnetic correlations have been argued to be the cause of the d-wave superconductivity and the pseudogap phenomena exhibited by the cuprates. Although the antiferromagnetic response in the pseudogap state has been reported for a number of compounds, there exists no information for structurally simple HgBa2CuO(4+δ). Here we report neutron-scattering results for HgBa2CuO(4+δ) (superconducting transition temperature Tc≈71 K, pseudogap temperature T*≈305 K) that demonstrate the absence of the two most prominent features of the magnetic excitation spectrum of the cuprates: the X-shaped 'hourglass' response and the resonance mode in the superconducting state. Instead, the response is Y-shaped, gapped and significantly enhanced below T*, and hence a prominent signature of the pseudogap state.

Hourglass Dispersion and Resonance of Magnetic Excitations in the Superconducting State of the Single-Layer Cuprate HgBa_{2}CuO_{4+δ} Near Optimal Doping.

We use neutron scattering to study magnetic excitations near the antiferromagnetic wave vector in the underdoped single-layer cuprate HgBa_{2}CuO_{4+δ} (superconducting transition temperature T_{c}≈88 K, pseudogap temperature T^{*}≈220 K). The response is distinctly enhanced below T^{*} and exhibits a Y-shaped dispersion in the pseudogap state, whereas the superconducting state features an X-shaped (hourglass) dispersion and a further resonancelike enhancement. A large spin gap of about 40 meV is observed in both states. This phenomenology is reminiscent of that exhibited by bilayer cuprates. The resonance spectral weight, irrespective of doping and compound, scales linearly with the putative binding energy of a spin exciton described by an itinerant-spin formalism.

Charge order and its connection with Fermi-liquid charge transport in a pristine high-T(c) cuprate.

Electronic inhomogeneity appears to be an inherent characteristic of the enigmatic cuprate superconductors. Here we report the observation of charge-density-wave correlations in the model cuprate superconductor HgBa2CuO(4+δ) (T(c)=72 K) via bulk Cu L3-edge-resonant X-ray scattering. At the measured hole-doping level, both the short-range charge modulations and Fermi-liquid transport appear below the same temperature of about 200 K. Our result points to a unifying picture in which these two phenomena are preceded at the higher pseudogap temperature by q=0 magnetic order and the build-up of significant dynamic antiferromagnetic correlations. The magnitude of the charge modulation wave vector is consistent with the size of the electron pocket implied by quantum oscillation and Hall effect measurements for HgBa2CuO(4+δ) and with corresponding results for YBa2Cu3O(6+δ), which indicates that charge-density-wave correlations are universally responsible for the low-temperature quantum oscillation phenomenon.

In-plane magnetoresistance obeys Kohler's rule in the pseudogap phase of cuprate superconductors.

We report in-plane resistivity (ρ) and transverse magnetoresistance (MR) measurements for underdoped HgBa(2)CuO(4+δ) (Hg1201). Contrary to the long-standing view that Kohler's rule is strongly violated in underdoped cuprates, we find that it is in fact satisfied in the pseudogap phase of Hg1201. The transverse MR shows a quadratic field dependence, δρ/ρ(0)=aH(2), with a(T)∝T(-4). In combination with the observed ρ∝T(2) dependence, this is consistent with a single Fermi-liquid quasiparticle scattering rate. We show that this behavior is typically masked in cuprates with lower structural symmetry or strong disorder effects.

Photo-enhanced antinodal conductivity in the pseudogap state of high-Tc cuprates.

A major challenge in understanding the cuprate superconductors is to clarify the nature of the fundamental electronic correlations that lead to the pseudogap phenomenon. Here we use ultrashort light pulses to prepare a non-thermal distribution of excitations and capture novel properties that are hidden at equilibrium. Using a broadband (0.5-2 eV) probe, we are able to track the dynamics of the dielectric function and unveil an anomalous decrease in the scattering rate of the charge carriers in a pseudogap-like region of the temperature (T) and hole-doping (p) phase diagram. In this region, delimited by a well-defined T*neq(p) line, the photoexcitation process triggers the evolution of antinodal excitations from gapped (localized) to delocalized quasiparticles characterized by a longer lifetime. The novel concept of photo-enhanced antinodal conductivity is naturally explained within the single-band Hubbard model, in which the short-range Coulomb repulsion leads to a k-space differentiation between nodal quasiparticles and antinodal excitations.

Doping-dependent photon scattering resonance in the model high-temperature superconductor HgBa2CuO4+δ revealed by Raman scattering and optical ellipsometry.

We study the model high-temperature superconductor HgBa(2)CuO(4+δ) with electronic Raman scattering and optical ellipsometry over a wide doping range. The dependence of the resonant Raman cross section on the incident photon energy changes drastically as a function of doping, in a manner that corresponds to a rearrangement of the interband optical transitions seen with ellipsometry. This doping-dependent Raman resonance allows us to reconcile the apparent discrepancy between Raman and x-ray detection of magnetic fluctuations in superconducting cuprates. Intriguingly, the strongest variation occurs across the doping level where the antinodal superconducting gap appears to reach its maximum.

Absence of static loop-current magnetism at the apical oxygen site in HgBa2CuO4+δ from NMR.

The simple structure of HgBa(2)CuO(4+δ) (Hg1201) is ideal among cuprates for study of the pseudogap phase as a broken symmetry state. We have performed (17)O nuclear magnetic resonance on an underdoped Hg1201 crystal with a transition temperature of 74 K to look for circulating loop currents proposed theoretically and inferred from neutron scattering. The narrow spectra preclude static local fields in the pseudogap phase at the apical site, suggesting that the moments observed with neutrons are fluctuating. The nuclear magnetic resonance frequency shifts are consistent with a dipolar field from the Cu(2+) site.

Viscoelastic response of the periodontal ligament: an experimental-numerical analysis.

A viscoelastic constitutive model for the periodontal ligament (PDL) capable of accounting for large strains, anisotropy, and inelastic time-dependent effects was developed. Anisotropy characteristics are determined by the composite nature of the tissue and, in particular, by the distribution of collagen fibres. Time-dependent viscous phenomena are due to microstructural modifications during loading, such as fluid fluxes moving through the solid matrix and the internal rearrangement of fibers and constitutive adaptation. The viscoelastic model presented here was implemented in a general purpose finite element code. In vitro experimental tests were carried out on the PDL specimens of adult pigs to obtain stress-relaxation and cyclic stress-strain curves. The comparison of experimental and numerical results revealed good correspondence and confirmed the capability of the formulation assumed to properly interpret the viscoelastic behavior of the PDL.

A transversally isotropic elasto-damage constitutive model for the periodontal ligament.

A numerical formulation of an elasto-damage constitutive model was developed and implemented in a finite element software to investigate the biomechanical response of the periodontal ligament (PDL). The mathematical framework accounts for the description of large strains, anisotropy and inelastic phenomena. The anisotropic mechanical response is caused by the spatial orientation of the sub-structures of the tissue, such as collagen fibres. Inelastic behaviour, induced by high level strains, is modelled by means of damage models. In vitro experimental testing on PDL samples from pigs was performed to obtain tensile stress-strain curves. A finite element analysis is presented in order to define a general numerical approach. A comparison of numerical and experimental data is provided in order to show the reliability and effectiveness of the formulation assumed.

[Experimental model of tooth mobility in the human "in vivo"]. / Experimentelle Untersuchung der Zahnbeweglichkeit am Menschen "in vivo".

The aim of the present study was to investigate experimentally the mechanical properties of tooth deflection under external loading. These properties have a significant impact on tooth movement during orthodontic treatment. The stresses and strains caused by tooth movement influence bone remodelling, which is the basis of orthodontic treatment. The movement of a tooth as a direct reaction to the forces acting on it is termed "initial" movement. It is nonlinear and has a clearly time-dependent component. While the initial tooth movement represents the totality of the reaction mechanisms of all the tissues of the tooth unit, it is determined primarily by the mechanical properties of the periodontal ligament (PDL). The PDL is the softest tissue of the tooth unit and is therefore subject to the largest deformations when forces act on the crown of the tooth. The objective of orthodontic treatment is to achieve as precise and rapid tooth movement as possible, without provoking such undesired effects as bone and root resorption. To enable the implementation of an optimal orthodontic force system that meets these requirements, a thorough knowledge of the biomechanics of tooth movement is a must.

[Joint empyema]. / Gelenkempyem.

Bacterial joint infection is rare but may have an unfavourable functional aotcome. The different stages of purulent arthritis, depending on the pathophysiological developments, require different treatment measures. Clinical examination, analysis of joint tap and arthroscopy are crucial for diagnosis. Surgical management comprises: (1) open or arthroscopic débridement with intensive flush lavage; (2) postoperative drainage and flush lavage; (3) early and continuous active and passive motion. Recovery will be complete only if therapy is instituted as early as possible (within 3 days). Joint empyema must therefore be treated as a surgical emergency.

[Traumatic peripheral vascular injuries]. / Traumatische periphere Gefässverletzungen.

2-4% of vascular injuries need operative reconstruction. In polytraumatized patients the rate is even 10%. Arterial vascular repair should precede venous reconstruction and orthopaedic stabilization due to limb threatening ischemia. Penetration or blunt vascular trauma result either in acute blood loss, ischemia or compartmental compression. Reperfusion syndrome leads to vital threat of patient. Clinical assessment, measurement of limb pressures using a Doppler device and use of duplex ultrasonography are reliable adjuncts in the rapid evaluation. Arteriography is rarely indicated and should be spared for patients with abnormal physical examination. Minimizing ischemia (6-8 h) is an important factor in maximizing limb salvage. Vascular repair include direct anastomosis or lateral suture repair mostly combined with primary shortening of the extremity. In most cases autogenous vein graft is required. Rethrombosis, arteriovenous fistula and pseudoaneurysms are possible complications. Stabilisation of the fracture has priority over vascular reconstruction. The initial steps to success are surgical debridement, adequate bony stabilization mostly by external fixation, revascularisation of vascular injury, immediate fascial decompression and early soft-tissue reconstruction. The best results are obtained when a multidisciplinary approach is used combining expertise in orthopedic surgery, vascular surgery and plastic surgery.

[Therapy of soft tissue injuries--biological strategies]. / Therapie des Weichteilschadens--biologische Strategien.

The traumatic soft tissue injury plays a central role in fracture healing. The knowledge of pathophysiological mechanisms has completely changed the management and therapy of injuries accompanied by soft tissue lesions. Treatment is aiming for prevention of the circle of hypoxia, microvascular perfusion disturbance, increased membrane permeability and potential infections. General therapeutic principles are decontamination, debridement, revascularisation and decompression. Modern methods of soft tissue treatment take these principles into consideration.

[Trauma in elderly patients]. / Das Trauma beim alten Menschen.

The increasing proportion of old and very old people in the population has increased the task of treatment in the field of surgery and its main points. The decreasing function of and changes to the skeleton caused by osteoporosis have led to a number of fractures. The fracture near the hip joint is typical for this section of the population. 1180 patients from the Jena surgical clinic/casualty were analysed; the average age was over 75 years and the most common cause of accident was a fall. A quick operative treatment is recommended. In comparison with the risk factor of the ASA-classification 1.6% with factor I and 44.4% with factor IV died. Postoperative treatment is very important.

[Principles of osteosynthesis of the hand]. / Prinzipien der Osteosynthese an der Hand.

In cases of joint fractures as well as in dislocated and open fractures of the hand special standards concerning operation methods have to be set. Treatment of soft tissue damage accompanying the fracture is in no other region of the body so important. Therefore the current efforts for development of an AO-classification for fractures of the hand taking into account the soft tissue damage are of major significance. Special features of miniosteosynthesis compared to conventional osteosynthesis are the subject of this study. The use of the miniplate especially in juxtaarticular fractures of the hand due to complex injuries or replantations can overcome the disadvantages of joint-bridging K-wires. Osteosyntheses of the hand are making high technical demands on surgeons and are not at all operations for beginners.

[Amputation injuries of the upper extremity--early complications after replantation and revascularization]. / Amputationsverletzungen der oberen Extremität--Frühkomplikationen nach Replantation und Revaskularisation.

Within a time of ten years 144 patients with difficult injuries on their hands were operated. These were 95 replantations and 102 revascularizations. 26 patients had to be operated again because of arterial and venous thrombosis. 46% of our patients had early vascular complications already within 24 hours. The frequency of thrombosis was increasing with the accompanying soft tissue injury and therefore with the gravity of the trauma. Avulsion injuries had of course the worst prognosis. After diagnosis of vascular occlusion within the replanted finger there should be a quick surgical revision of the anastomosis. With the help of application of urokinase into the artery we could create the circulation without any new production of the anastomosis in two cases. With a subtile technique of the disposition of the anastomosis and two venous connections to one artery with the replanted fingers we could reduce the rate of thrombosis and improve the results.

[Drug modification of post-traumatic edema of the extremities by the proteinase inhibitor aprotinin. An animal experiment study]. / Die medikamentöse Beeinflussung des posttraumatischen Extremitätenödems durch den Proteinaseninhibitor Aprotinin. Eine tierexperimentelle Studie.

Posttraumatic edema remains a serious problem in traumatology. Unrecognized or improperly treated, edema poses a threat to the survival of any extremity, particularly the hand, where a number of intricate functional structures are at stake. This study, as well as other recent clinical and experimental work, show that aprotinin, a proteinase inhibitor, is valuable in the treatment of posttraumatic edema, provided it is given as early as possible and in an adequate dosage.

[Results and late sequelae of colectomy]. / Ergebnisse und Spätfolgen nach Kolektomie.

Results after 55 colectomies are reported in the period from 1962-1986. The surgical intervention was indicated by ulcerative colitis in 19, Crohn's disease in 18 and familial polyposis of the colon in 18 cases. 37 total colectomies, 12 subtotal colectomies with ileorectal anastomosis and 6 colectomies with a remaining terminal closed stump of the rectum were performed. During the period of observation postoperative lethality decreased from 37% to 6%. Death was most frequently caused by thromboemboli and peritonitis. In 44% of the patients ill with familial polyposis malignant degeneration could be observed. 3 died by generalized metastases. Metabolism of protein, lipid and electrolyte showed no essential disturbances after colectomy. Intestinal assimilation was nearly standard. More difficult is social reintegration.