1,674 research outputs found

    Quantum dynamics of crystals of molecular nanomagnets inside a resonant cavity

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    It is shown that crystals of molecular nanomagnets exhibit enhanced magnetic relaxation when placed inside a resonant cavity. Strong dependence of the magnetization curve on the geometry of the cavity has been observed, providing evidence of the coherent microwave radiation by the crystals. A similar dependence has been found for a crystal placed between Fabry-Perot superconducting mirrors. These observations open the possibility of building a nanomagnetic microwave laser pumped by the magnetic field

    Immunohistochemical determination of the appropriate anti-hTERT antibodies for in situ detection of telomerase activity in frozen sections of head and neck squamous cell carcinomas and tumor margin tissues

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    In previous studies we demonstrated telomerase activity in frozen tissue from head and neck squamous cell carcinoma (HNSCC) and their tumor-free tumor margins. In the present study frozen sections from the same tissues were examined for in situ presence of hTERT. In preliminary investigations we established that the most suitable method of tissue preparation was fixation in acetone and methanol followed by steaming and visualization by APAAP. Most of the assays involved eleven anti-hTERT antibodies and were supplemented with the inclusion of antibodies Ki-67, anti-nucleolin and CD45. hTERT expression was investigated in the tissues of 61 patients with HNSCC and 37 patients without tumor. Semi-quantitative immunoreactive scores were correlated with telomerase activity. We examined the prognostic significance of hTERT expression with Kaplan-Meier curves and tested the immunological specificity of the antibodies by immunoabsorption with two hTERT peptides and a nucleolin peptide. Nuclear staining of satisfactory distribution and intensity was achieved in seven anti-hTERT antibodies both in the carcinomas and in the squamous epithelia of the tumor resection margins and in the control tissues. Proof of hTERT did not differ from telomerase activity. The telomerase activity demonstrated in tumor-free resection margins and in control tissues did, however, correlate with lymphocytic-monocytic infiltration (CD45 expression). This telomerase activity might be related to nuclear hTERT expression in the squamous epithelium, given that the hTERT score values in the connective tissue tended to be negative. The prognostic significance of hTERT expression demonstrated on paraffin sections from different tumor localizations was not confirmed for the frozen sections of patients with HNSCC. The hTERT specificity of the monoclonal NCL-L-hTERT, whose use as an antibody against hTERT has been questioned, was re-examined with immunohistochemical methods, but the intensity of its immunoabsorption with the nucleolin peptide did not exceed that observed in the other anti-hTERT antibodies

    Compositions of dikes and lavas from the Pito Deep Rift: Implications for crustal accretion at superfast spreading centers

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    The northwest trending walls of the Pito Deep Rift (PDR), a tectonic window in the southeast Pacific, expose in situ oceanic crust generated ∼3 Ma at the superfast spreading southern East Pacific Rise (SEPR). Whole rock analyses were performed on over 200 samples of dikes and lavas recovered from two ∼8 km2 study areas. Most of the PDR samples are incompatible-element- depleted normal mid-ocean ridge basalts (NMORB; (La/Sm)N < 1.0) that show typical tholeiitic fractionation trends. Correlated variations in Pb isotope ratios, rare earth element patterns, and ratios of incompatible elements (e.g., (Ce/Yb)N) are best explained by mixing curves between two enriched and one depleted mantle sources. Pb isotope compositions of most PDR NMORB are offset from SEPR data toward higher values of 207Pb/ 204Pb, suggesting that an enriched component of the mantle was present in this region in the past ~3 Ma but is not evident today. Overall, the PDR crust is highly variable in composition over long and short spatial scales, demonstrating that chemically distinct lavas and dikes can be emplaced within the same segment over short timescales. However, the limited spatial distribution of high 206Pb/204Pb samples and the occurrence of relatively homogeneous MgO compositions (ranging <2.5 wt %) within a few of the individual dive transects (over distances of ∼1 km) suggests that the mantle source composition evolved and magmatic temperatures persisted over timescales of tens of thousands of years. The high degree of chemical variability between pairs of adjacent dikes is interpreted as evidence for along-axis transport of magma from chemically distinct portions of the melt lens. Our findings suggest that lateral dike propagation occurs to a significant degree at superfast spreading centers

    Achtergronddocument Midterm meting Monitor Effectindicatoren Agenda Vitaal Platteland

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    De Monitor AVP is een systeem waarin eenduidige gegevens worden opgenomen voor monitoring van effecten, resultaten en prestaties van de beleidsdoelstellingen opgenomen in de Agenda Vitaal Platteland (AVP) van het ministerie van Economische Zaken, Landbouw & Innovatie (EL&I). Dit document geeft de resultaten en achtergrondinformatie van de midterm meting en de methoden van de metingen van de afzonderlijke effectindicatoren van de Monitor AVP. De effectindicatoren zijn bedoeld om de maatschappelijke effecten van de Agenda Vitaal Platteland inzichtelijk te maken. Dit achtergronddocument is opgesteld om de continuïteit voor toekomstige herhalingsmetingen te waarborgen

    Node-weighted Steiner tree and group Steiner tree in planar graphs

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    We improve the approximation ratios for two optimization problems in planar graphs. For node-weighted Steiner tree, a classical network-optimization problem, the best achievable approximation ratio in general graphs is Θ [theta] (logn), and nothing better was previously known for planar graphs. We give a constant-factor approximation for planar graphs. Our algorithm generalizes to allow as input any nontrivial minor-closed graph family, and also generalizes to address other optimization problems such as Steiner forest, prize-collecting Steiner tree, and network-formation games. The second problem we address is group Steiner tree: given a graph with edge weights and a collection of groups (subsets of nodes), find a minimum-weight connected subgraph that includes at least one node from each group. The best approximation ratio known in general graphs is O(log3 [superscript 3] n), or O(log2 [superscript 2] n) when the host graph is a tree. We obtain an O(log n polyloglog n) approximation algorithm for the special case where the graph is planar embedded and each group is the set of nodes on a face. We obtain the same approximation ratio for the minimum-weight tour that must visit each group

    Fine-specificity of cytotoxic T lymphocytes which recognize conserved epitopes of the Gag protein of human immunodeficiency virus type 1

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    Human immunodeficiency virus type 1 (HIV-1) Gag-specific cytotoxic T lymphocyte (CTL) responses were studied in seven seropositive long-term asymptomatic individuals (CDC A1)with stable CD4 counts for more than 8 years. Using a set of partially overlapping peptides covering the whole Gag, five 15-20-mer peptides were found to contain CTL epitopes. Further characterization of these epitopes revealed a new HLA-A25-restricted CTL epitope in p24, p24203-212 ETINEEAAEW. This region of Gag highly conserved in clades B and D of HIV-1. Naturally occurring amino acid sequences, containing p24203D (consensus HIV-1 clades A, C, F, G and H) or p24204I(HIV-2(ROD)) were not recognized by CTL recognizing the index peptide. No virus variants with mutations in this sequence were found in peripheral blood mononuclear cells from the HIV-1-infected individual concerned during the 8 year observation period, indicating that the virus had not escaped from the observed CTL response.</p

    Only connect: unifying the social in social work and social media

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    This paper utilises ‘Only Connect’, the epigraph from Forster’s novel ‘Howards End’ as the starting point for exploring the challenges and opportunities of integrating social networking with relationship based social work practice. The paper discusses the more deleterious implications of social networking, whilst assuming a deliberately optimistic stance to uncover ways in which the opportunities afforded by online space can be utilised effectively within social work education and practice. Whilst recognising that social networking platforms are transforming constantly, the paper adopts Kaplan’s definition of social media as a ‘group of internet based applications that build on the ideological and technological foundations of Web 2.0’. Whilst much of the discussion within the paper relates to Twitter and Facebook, two of the most endemic international social networking platforms, it is also applicable to myriad forms of social networking. The paper begins with a discussion of UK professional conduct cases and explores these both within Klein’s concept of splitting and historical attitudes to new technologies. Drawing from emerging research data and other examples, the positive relational practices educed by social media within social work education and practice are emphasised and discussed. The paper concludes by highlighting Forster’s plea for connection and recommending that social work embraces the renewed opportunities provided by online networking

    Training specialists to write appropriate reply letters to general practitioners about patients with medically unexplained physical symptoms; A cluster-randomized trial.

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    Objective: To evaluate effects of a communication training for specialists on the quality of their reply letters to general practitioners (GPs) about patients with medically unexplained physical symptoms (MUPS). Methods: Before randomization, specialists included ≤3 MUPS patients in a multi-center cluster-randomized trial. In 14 h of MUPS-specific communication training, 2.5 h focused on reply letters. Letters were discussed with regard to reporting and answering GPs' referral questions and patients' questions, and to reporting findings, explaining MUPS with perpetuating factors and giving advice. After the training, all doctors again included ≤3 MUPS patients. Reply letters to GPs were assessed for quality and blindly rated on a digital scale. Results: We recruited 478 MUPS patients and 123 specialists; 80% of the doctors wrote ≥1 reply letters, 285 letters were assessed. Trained doctors reported (61% versus 37%, OR=2.55, F(1281)=6.60, pgroup*time=.01) and answered (63% versus 33%, OR=3.31, F(1281)=5.36, pgroup*time=.02) patients' questions more frequently than untrained doctors. Conclusion: Training improves reply letters with regard to patients' questions, but not with regard to the following: GPs' referral questions, somatic findings, additional testing, explaining, and advice. Practice implications: Training specialists to write appropriate reply letters needs more focus on explanation and advice

    New precise determination of the \tau lepton mass at KEDR detector

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    The status of the experiment on the precise τ\tau lepton mass measurement running at the VEPP-4M collider with the KEDR detector is reported. The mass value is evaluated from the τ+τ−\tau^+\tau^- cross section behaviour around the production threshold. The preliminary result based on 6.7 pb−1^{-1} of data is mτ=1776.80−0.23+0.25±0.15m_{\tau}=1776.80^{+0.25}_{-0.23} \pm 0.15 MeV. Using 0.8 pb−1^{-1} of data collected at the ψ′\psi' peak the preliminary result is also obtained: ΓeeBττ(ψ′)=7.2±2.1\Gamma_{ee}B_{\tau\tau}(\psi') = 7.2 \pm 2.1 eV.Comment: 6 pages, 8 figures; The 9th International Workshop on Tau-Lepton Physics, Tau0
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