306 research outputs found

    Muon Spin Relaxation and Susceptibility Studies of Pure and Doped Spin 1/2 Kagom\'{e}-like system (Cux_xZn1βˆ’x_{1-x})3_{3}V2_{2}O7_7(OH)2_{2} 2H2_2O

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    Muon spin relaxation (ΞΌ\muSR) and magnetic susceptibility measurements have been performed on the pure and diluted spin 1/2 kagom\'{e} system (Cux_xZn1βˆ’x_{1-x})3_{3}V2_{2}O7_7(OH)2_{2} 2H2_2O. In the pure x=1x=1 system we found a slowing down of Cu spin fluctuations with decreasing temperature towards T∼1T \sim 1 K, followed by slow and nearly temperature-independent spin fluctuations persisting down to TT = 50 mK, indicative of quantum fluctuations. No indication of static spin freezing was detected in either of the pure (xx=1.0) or diluted samples. The observed magnitude of fluctuating fields indicates that the slow spin fluctuations represent an intrinsic property of kagom\'e network rather than impurity spins.Comment: 4 pges, 4 color figures, Phys. Rev. Lett. in pres

    Muon Spin Relaxation Studies of Magnetic-Field-Induced Effects in High-TcT_{c} Superconductors

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    Muon spin relaxation (ΞΌ\muSR) measurements in high transverse magnetic fields (βˆ₯c^\parallel \hat c) revealed strong field-induced quasi-static magnetism in the underdoped and Eu doped (La,Sr)2_{2}CuO4_{4} and La1.875_{1.875}Ba0.125_{0.125}CuO4_{4}, existing well above TcT_{c} and TNT_{N}. The susceptibility-counterpart of Cu spin polarization, derived from the muon spin relaxation rate, exhibits a divergent behavior towards T∼25T \sim 25 K. No field-induced magnetism was detected in overdoped La1.81_{1.81}Sr0.19_{0.19}CuO4_{4}, optimally doped Bi2212, and Zn-doped YBa2_{2}Cu3_{3}O7_{7}.Comment: 4 pages, 4 color figure

    Effectiveness of adenoidectomy in children with recurrent upper respiratory tract infections: open randomised controlled trial

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    Objective To assess the effectiveness of adenoidectomy in children with recurrent upper respiratory tract infections

    Site-Dilution in quasi one-dimensional antiferromagnet Sr2(Cu1-xPdx)O3: reduction of Neel Temperature and spatial distribution of ordered moment sizes

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    We investigate the Neel temperature of Sr2CuO3 as a function of the site dilution at the Cu (S=1/2) sites with Pd (S=0), utilizing the muon spin relaxation (muSR) technique. The Neel temperature, which is Tn=5.4K for the undoped system, becomes significantly reduced for less than one percent of doping Pd, giving a support for the previous proposal for the good one-dimensionality. The Pd concentration dependence of the Neel temperature is compared with a recent theoretical study (S. Eggert, I. Affleck and M.D.P. Horton, Phys. Rev. Lett. 89, 47202 (2002)) of weakly coupled one-dimensional antiferromagnetic chains of S=1/2 spins, and a quantitative agreement is found. The inhomogeneity of the ordered moment sizes is characterized by the muSR time spectra. We propose a model that the ordered moment size recovers away from the dopant S=0 sites with a recovery length of \xi = 150-200 sites. The origin of the finite recovery length \xi for the gapless S=1/2 antiferromagnetic chain is compared to the estimate based on the effective staggered magnetic field from the neighboring chains.Comment: 10 pages, 9 figures, submitted to PR

    Effective treatment of liver metastases with photodynamic therapy, using the second-generation photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC), in a rat model

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    The only curative treatment for patients with liver metastases to date is surgery, but few patients are suitable candidates for hepatic resection. The majority of patients will have to rely on other treatment modalities for palliation. Photodynamic therapy (PDT) could be a selective, minimally invasive treatment for patients with liver metastases. We studied PDT in an implanted colon carcinoma in the liver of Wag/Rij rats, using the photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC). mTHPC tissue kinetics were studied using ex vivo extractions and in vivo fluorescence measurements. Both methods showed that mTHPC kinetics were different for liver and tumour tissue. After initial high levels at 4 h after administration (0.1 and 0.3 mg kgβˆ’1) mTHPC in liver tissue decreased rapidly in time. In tumour tissue no decrease in photosensitizer levels occurred, with mTHPC remaining high up to 48 h after administration. Both concentration data and fluorescence data showed an increase in tumour to liver ratios of up to 6.3 and 5.0 respectively. Illumination with 652 nm (15 J) resulted in extensive damage to tumour tissue, with necrosis of up to 13 mm in diameter. Damage to normal liver tissue was mild and transient as serum aspartate aminotransferase and alanine aminotransferase levels normalized within a week after PDT treatment. Long-term effects of mTHPC-PDT were studied on day 28 after treatment. Regardless of drug dose and drug–light interval, PDT with mTHPC resulted in complete tumour remission in 27 out of 31 treated animals (87%), with only four animals in which tumour regrowth was observed. Non-responding tumours proved to be significantly larger (P < 0.001) in size before PDT treatment. This study demonstrates that mTHPC is retained in an intrahepatic tumour and that mTHPC-PDT is capable of inducing complete tumour remission of liver tumours. Β© 1999 Cancer Research Campaig

    IDEAL-D Framework for Device Innovation: A Consensus Statement on the Preclinical Stage

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    OBJECTIVE: To extend the IDEAL Framework for device innovation, IDEAL-D, to include the preclinical stage of development (Stage 0). BACKGROUND: In previous work, the IDEAL collaboration has proposed frameworks for new surgical techniques and complex therapeutic technologies, the central tenet being that development and evaluation can and should proceed together in an ordered and logical manner that balances innovation and safety. METHODS: Following agreement at the IDEAL Collaboration Council, a multidisciplinary working group was formed comprising 12 representatives from healthcare, academia, industry, and a patient advocate. The group conducted a series of discussions following the principles used in the development of the original IDEAL Framework. Importantly, IDEAL aims for maximal transparency, optimal validity in the evaluation of primary effects and minimisation of potential risk to patients or others. The proposals were subjected to further review and editing by members of the IDEAL Council before a final consensus version was adopted. RESULTS: In considering which studies are required before a first-in-human study, we have: (1) classified devices according to what they do and the risks they carry, (2) classified studies according to what they show about the device, and (3) made recommendations based on the principle that the more invasive and high risk a device is, the greater proof required of their safety and effectiveness prior to progression to clinical studies (Stage 1). CONCLUSIONS: The proposed recommendations for preclinical evaluation of medical devices represent a proportionate and pragmatic approach that balances the de-risking of first-in-human translational studies against the benefits of rapid translation of new devices into clinical practice

    What kind of heat loss requirements NZEB and deep renovation sets for building envelope?

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    In most of countries the energy performance of buildings is defined as (primary) energy use of whole buildingΓ’ s (heating, cooling, ventilation, DHW, lighting, HVAC auxiliary, appliances), not as specific requirements for building envelope. For construction companies of production of modular renovation panels it in necessary to know heat loss properties of building envelope (U, W/(m2Γ’ K); Γ― , W/(mΓ’ K); Γ― Β£, W/K; q50, m3/(hΓ’ m2)). In this study it is analyzed what kind of heat loss requirements exists for building envelope to meet on annual basis to following targets: nZEB i.e. national nearly zero energy definition; deep energy renovation with 80 % reduction of primary energy; ZEB i.e. net Zero Energy Building = the annual primary energy use = 0 kWh/(m² a). Indoor climate and energy calculations were made based on national energy calculation methodologies in six countries: Denmark, Estonia, Latvia, Czech Republic, Portugal, and Netherlands. Requirements for heat loss of building envelope vary depending on requirements on indoor climate and energy performance in specific country, outdoor climate, availability of renewable energy, and building typology. The thermal transmittance of the modular wall panels for nZEB was Γ’ 5% from pre renovation thermal transmittance in Latvia, Γ’ 10% in Estonia and up to 50% in Portugal. For roof the decrease of thermal transmittance was smaller mainly due to smaller thermal transmittance before renovation. Results show the difficulties to reach ZEB with multi-story apartment buildings in cold climate. There are not enough places to install renewables for energy production on site.The study has been conducted in the projects H2020 MoreConnect, TK146 the Estonian Centre of Excellence in Zero Energy and Resource Efficient Smart Buildings and Districts, ZEBE, IUT1βˆ’15 Nearly-zero energy solutions and their implementation on deep renovation of buildings

    Overview of Analytical Models for the Design of Linear and Planar Motors

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    Reconciling Semiclassical and Bohmian Mechanics: III. Scattering states for continuous potentials

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    In a previous paper [J. Chem. Phys. 121 4501 (2004)] a unique bipolar decomposition, Psi = Psi1 + Psi2 was presented for stationary bound states Psi of the one-dimensional Schroedinger equation, such that the components Psi1 and Psi2 approach their semiclassical WKB analogs in the large action limit. The corresponding bipolar quantum trajectories, as defined in the usual Bohmian mechanical formulation, are classical-like and well-behaved, even when Psi has many nodes, or is wildly oscillatory. A modification for discontinuous potential stationary stattering states was presented in a second paper [J. Chem. Phys. 124 034115 (2006)], whose generalization for continuous potentials is given here. The result is an exact quantum scattering methodology using classical trajectories. For additional convenience in handling the tunneling case, a constant velocity trajectory version is also developed.Comment: 16 pages and 14 figure

    18F-FDG PET/CT for diagnosing infectious complications in patients with severe neutropenia after intensive chemotherapy for haematological malignancy or stem cell transplantation

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    Item does not contain fulltextPURPOSE: Between 30 and 50% of febrile neutropenic episodes are accounted for by infection. C-reactive protein (CRP) is a nonspecific parameter for infection and inflammation but might be employed as a trigger for diagnosis. The aim of the study was to evaluate whether (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT can be used to detect inflammatory foci in neutropenic patients with elevated CRP and whether it helps to direct treatment. METHODS: Twenty-eight consecutive patients with neutropenia as a result of intensive chemotherapy for haematological malignancies or myeloablative therapy for haematopoietic stem cell transplantation were prospectively included. (18)F-FDG PET/CT was added to the regular diagnostic workup once the CRP level rose above 50 mg/l. RESULTS: Pathological FDG uptake was found in 26 of 28 cases despite peripheral neutrophil counts less than 0.1 x 10(-9)/l in 26 patients: in the digestive tract in 18 cases, around the tract of the central venous catheter (CVC) in 9 and in the lungs in 7 cases. FDG uptake in the CVC tract was associated with coagulase-negative staphylococcal bacteraemia (p < 0.001) and deep venous thrombosis (p = 0.002). The number of patients having Streptococcus mitis bacteraemia appeared to be higher in patients with grade 3 oesophageal FDG uptake (p = 0.08). Pulmonary FDG uptake was associated with the presence of invasive fungal disease (p = 0.04). CONCLUSION: (18)F-FDG PET/CT scanning during chemotherapy-induced febrile neutropenia and increased CRP is able to detect localized foci of infection and inflammation despite the absence of circulating neutrophils. Besides its potential role in detecting CVC-related infection during febrile neutropenia, the high negative predictive value of (18)F-FDG PET/CT is important for avoiding unnecessary diagnostic tests and therapy.1 januari 201
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