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In conventional superconductors, lattice vibrations (phonons) mediate the attraction between electrons that is responsible for superconductivity 1 . The high transition temperatures (high- T c ) of the copper oxide superconductors has led to collective spin excitations being proposed as the mediating excitations in these materials 2 . The mediating excitations must be strongly coupled to the conduction electrons, have energy greater than the pairing energy, and be present at T c . The most obvious feature in the magnetic excitations of high- T c superconductors such as YBa 2 Cu 3 O 6+ x is the so-called ‘resonance’ 3 , 4 , 5 , 6 . Although the resonance may be strongly coupled to the superconductivity 3 , 4 , 5 , 6 , 7 , 8 , it is unlikely to be the main cause, because it has not been found in the La 2- x (Ba,Sr) x CuO 4 family and is not universally present in Bi 2 Sr 2 CaCu 2 O 8+ δ (ref. 9 ). Here we use inelastic neutron scattering to characterize possible mediating excitations at higher energies in YBa 2 Cu 3 O 6.6 . We observe a square-shaped continuum of excitations peaked at incommensurate positions. These excitations have energies greater than the superconducting pairing energy, are present at T c , and have spectral weight far exceeding that of the ‘resonance’. The discovery of similar excitations in La 2– x Ba x CuO 4 (ref. 10 ) suggests that they are a general property of the copper oxides, and a candidate for mediating the electron pairing.

Abortion outbreaks associated with congenital malformations in two distinct small-ruminant flocks were reported in Turkey in 2013-2014. This paper describes the first molecular characterization of Turkish Akabane virus strains in small-ruminant flocks using partial sequence analysis of the S segment and pathological findings.

One of the most striking properties of the high-transition-temperature (high- T c ) superconductors is that they are all derived from insulating antiferromagnetic parent compounds. The intimate relationship between magnetism and superconductivity in these copper oxide materials has intrigued researchers from the outset 1 , 2 , 3 , 4 , because it does not exist in conventional superconductors. Evidence for this link comes from neutron-scattering experiments that show the unambiguous presence of short-range antiferromagnetic correlations (excitations) in the high- T c superconductors. Even so, the role of such excitations in the pairing mechanism for superconductivity is still a subject of controversy 5 . For YBa 2 Cu 3 O 6+ x , where x controls the hole-doping level, the most prominent feature in the magnetic excitation spectrum is a sharp resonance (refs 6 , 7 , 8 , 9 , 10 , 11 ). Here we show that for underdoped YBa 2 Cu 3 O 6.6 , where x and T c are below their optimal values, modest magnetic fields suppress the resonance significantly, much more so for fields approximately perpendicular to the CuO 2 planes than for parallel fields. Our results indicate that the resonance measures pairing and phase coherence, suggesting that magnetism plays an important role in high- T c superconductivity. The persistence of a field effect above T c favours mechanisms in which the superconducting electron pairs are pre-formed in the normal state of underdoped copper oxide superconductors 12 , 13 , 14 , awaiting transition to the superconducting state.

An important feature of the high-transition-temperature (high- T c ) copper oxide superconductors is the magnetism that results from the spins associated with the incomplete outer electronic shells (3d 9 ) of the copper ions. Fluctuations of these spins give rise to magnetic excitations of the material, and might mediate the electron pairing that leads to superconductivity. If the mechanism for high- T c superconductivity is the same for all copper oxide systems, their spin fluctuations should be universal. But so far, theopposite has seemed to be the case: neutron scattering data reveal clear differences between the spin fluctuations for two major classes of high- T c materials, La 2− x Sr x CuO 4 ( 1 - 3 ) and YBa 2 Cu 3 O 7− x ( 4 - 6 ), whose respective building blocks are CuO 2 layers and bilayers. Here we report two-dimensional neutron-scattering imaging of YBa 2 Cu 3 O 6.6 , which reveals that the low-frequency magnetic excitations are virtually identical to those of similarly doped La 2− x Sr x CuO 4 . Thus, the high-temperature ( T c ≲ 92 K) superconductivity of the former materials may be related to spatially coherent low-frequency spin excitations that were previously thought to be unique to the lower- T c (<40 K) single-layer La 2− x Sr x CuO 4 family.

Understanding the magnetic excitations in high-temperature (high- T c ) copper-oxide superconductors is important because they may mediate the electron pairing for superconductivity 1 , 2 . By determining the wavevector ( Q ) and energy (ħ ω ) dependence of the magnetic excitations, it is possible to calculate the change in the exchange energy available to the superconducting condensation energy 3 , 4 , 5 . For the high- T c superconductor YBa 2 Cu 3 O 6+ x , the most prominent feature in the magnetic excitations is the resonance 6 , 7 , 8 , 9 , 10 , 11 , 12 . Suggestions that the resonance contributes a major part of the superconducting condensation 4 , 13 have not gained acceptance because the resonance is only a small portion of the total magnetic scattering 12 , 13 , 14 . Here, we report an extensive mapping of magnetic excitations for YBa 2 Cu 3 O 6.95 ( T c ∼93 K). Absolute intensity measurements of the full spectra allow us to estimate the change in the magnetic exchange energy between the normal and superconducting states, which is about 15 times larger than the superconducting condensation energy 15 , 16 —more than enough to provide the driving force for high- T c superconductivity in YBa 2 Cu 3 O 6.95 .

Understanding the behaviour of the electrons in the high-temperature copper oxide superconductors remains a challenging problem. An important class of models 1 , 2 , 3 , 4 , 5 argues that the distribution of electronic charge and spin is not homogeneous: rather, spin and charge adopt a dynamic arrangement in which the spins on the copper form antiferromagnetic stripes, separated by domain walls containing the charge 1 , 2 , 3 , 4 , 5 . The dynamic behaviour of the spins has been extensively studied by neutron scattering, and recent results 6 have shown that the low-frequency fluctuations for different classes of materials display a universal spatial behaviour that is consistent with the stripe picture. But arguments for the existence of the stripe phases are difficult to sustain without a demonstration that charge is distributed in the domain walls. Here we report phonon measurements for the YBa 2 Cu 3 O 7- x high-temperature superconductors, which reveal the presence of charge fluctuations. The inferred periodicity is that expected if the charge is located in the domain walls separating the spin stripes. Our results therefore provide strong support for the existence of a dynamic stripe phase in the high-temperature superconductors.

Vascular access is used as a lifeline for hemodialysis in patients with end stage renal disease failure (ESRD). Failure of arteriovenous fistula (AVF) maturation is still high. The purpose of this study was to research the effects of clopidogrel in combination with oral iloprost, a synthetic analog of prostacyclin PGI2. Ninety-six diabetic ESRD patients were divided into two groups. In the first group (Group 1, N = 50), clopidogrel (75 mg daily dose) and an oral prostacycline analog (200 mg daily dose) were administered. In the second group (Group 2, N = 46), placebo was given. All patients took study medication 7-10 days prior to surgery. A Doppler ultrasound (USG) was performed for measurement of arterial and venous diameters, and peak systolic velocity of arterial flow based on subsequent fistula adequacy. Autogenous AVFs were constructed in forearm as distally as possible in all patients. Both groups were followed-up for a year. In the placebo group, early AVF thrombosis was detected in two patients (4.3%). AVF maturation failure was noted in 14 patients (30.4%) in placebo group and in four patients (8%) in clopidogrel plus oral prostacycline analog group in the early postoperative period (P = 0.001). The mean maturation time was 38 ± 6.5 and 53 ± 12.8 days in study and placebo groups, respectively (P = 0.023). The mean blood flow was 352 ± 94 mL/min in placebo group and 604 ± 125 mL/min in study group (P = 0.001). The arterial end diastolic velocity was 116 ± 14 cm/s in study group and 72 ± 21 cm/s in placebo group (P = 0.036) 1 year after the surgery. Our data indicated that clopidogrel and oral prostacycline analog combination is effective and safe for the prevention of primary AVF failure in hemodialysis patients and decreased acute and chronic thrombotic events.

Abstract Objective: This study aimed to evaluate the bilateral forehand circulation using a 64-channel multidetector computed tomography (MDCT) as a noninvasive method to define criteria for an upper extremity arterial anatomy and pathology prior to the use of arterial conduits. Materials and Methods: Fifty-five patients with coronary artery disease who underwent total arterial coronary artery bypass grafting (CABG) were randomly selected for this prospective study. MDCT angiography was performed for 110 examinations of forearm and hand arterial anatomy. Prior to MDCT, Allen tests were performed in all patients with a normal result, except four. Thirteen patients had diabetes mellitus (DM), 8 had peripheral artery occlusive disease, and 19 had a history of smoking. Results: All arteries, including axillary, ulnar artery (UA) and radial artery (RA), were clearly visualized in all patients. Upper extremity anatomical and pathological results were examined in 16 patients (29.1%). Severely calcified RA and/or UA were found in 6 patients who had a moderate renal failure. Nearly total occlusion of the RA was detected in another two patients. Focal intimal RA calcification was recorded in 1 female and 3 male patients. Ten patients who had severe calcification or intimal sclerosis of the upper extremity arteries had DM. The remaining patients had normal forehand arterial circulation. A persistent median artery with the absence of radial and ulnar arteries and a high bifurcation of RA from the brachial artery was detected as an anatomic variation in seven patients (12.7%). Conclusions: The major advantages of MDCT angiography are its non-invasiveness and the ability to detect calcific subadventitial plaques, which are difficult to diagnose using conventional angiography. MDCT may be used as a safe and non-invasive method to assess RA and UA prior to harvesting the upper limb artery. Preoperative imaging of forehand arteries is a means to avoid unnecessary forearm exploration or the use of an unsuitable arterial conduit in CABG operations, especially in patients with DM and moderate renal impairment.

We report phonon measurements for YBa2Cu3O(7-x) high-temperature superconductors, which reveal the presence of charge fluctuations. The inferred periodicity is that expected if the charge is located in the domain walls separating the spin stripes. Our results therefore provide strong support for the existence of a dynamic stripe phase in the high-temperature superconductors. (Author)

Summary To analyse the levels of an indirect marker of ROS‐induced lipid peroxidation [i.e. malondialdehyde (MDA)] in both testes and the levels of matrix metalloproteinase‐2 (MMP‐2), matrix metalloproteinase‐9 (MMP‐9) and matrix metalloproteinase inhibitor‐1 (TIMP‐1) in the left testis after induction of varicocele and investigated the impact of micronised purified flavonoid fraction (MPFF) on these markers. Forty‐nine adolescent (6‐week‐old) male Wistar rats were included in this study. The rats were divided into seven groups as follows:Group‐1, control; Group‐2, sham; Group‐3, left varicocele‐induced; Group‐4, varicocele + varicocelectomy + MPFF‐treated (for 4 weeks); Group‐5, varicocele + MPFF‐treated (for 8 weeks); Group‐6, varicocele‐induced and 4 weeks later, MPFF‐treated (for 4 weeks); and Group‐7, varicocele + varicocelectomy. MDA was measured in the tissues of both testes using the thiobarbituric acid reactivity method. The ELISA method was used for the quantification of MMP‐2, MMP‐9 and TIMP‐1 in the left testicular tissue. The levels of MDA were significantly higher in the varicocele group than in the other groups. The MDA levels in the left testicular tissues of Group‐7 were significantly higher than those of Group 4 (P = 0.03). In the varicocele group, the MMP‐2 and MMP‐9 levels decreased, whereas the levels of TIMP‐1 increased. The tissue levels of MMP‐2 in Groups 4, 5 and 7 were significantly higher than those in Group 1 (P < 0.05).