63,301 research outputs found

    Preliminary studies identifying and quantifying trace metal impurities in illicit ecstasy tablets using atomic spectrometry techniques

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    This paper illustrates some preliminary investigations into using ICP-MS in combination with ET-AAS in the analysis of Ecstasy tablets. Results indicate that a combination of both techniques can show discriminating power between seizures. Descriptions of the modifications made to optimise the ET-AAS system are described

    Using problem frames with distributed architectures: a case for cardinality on interfaces

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    Certain classes of problems amenable to description using Problem Frames, in particular ones intended to be implemented using a distributed architecture, can benefit by the addition of a cardinality specification on the domain interfaces. This paper presents an example of such a problem, demonstrates the need for relationship cardinality, and proposes a notation to represent cardinality on domain interfaces

    Gauge Theory of Composite Fermions: Particle-Flux Separation in Quantum Hall Systems

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    Fractionalization phenomenon of electrons in quantum Hall states is studied in terms of U(1) gauge theory. We focus on the Chern-Simons(CS) fermion description of the quantum Hall effect(QHE) at the filling factor ν=p/(2pq±1)\nu=p/(2pq\pm 1), and show that the successful composite-fermions(CF) theory of Jain acquires a solid theoretical basis, which we call particle-flux separation(PFS). PFS can be studied efficiently by a gauge theory and characterized as a deconfinement phenomenon in the corresponding gauge dynamics. The PFS takes place at low temperatures, TTPFST \leq T_{\rm PFS}, where each electron or CS fermion splinters off into two quasiparticles, a fermionic chargeon and a bosonic fluxon. The chargeon is nothing but Jain's CF, and the fluxon carries 2q2q units of CS fluxes. At sufficiently low temperatures TTBC(<TPFS)T \leq T_{\rm BC} (< T_{\rm PFS}), fluxons Bose-condense uniformly and (partly) cancel the external magnetic field, producing the correlation holes. This partial cancellation validates the mean-field theory in Jain's CF approach. FQHE takes place at T<TBCT < T_{\rm BC} as a joint effect of (i) integer QHE of chargeons under the residual field ΔB\Delta B and (ii) Bose condensation of fluxons. We calculate the phase-transition temperature TPFST_{\rm PFS} and the CF mass. PFS is a counterpart of the charge-spin separation in the t-J model of high-TcT_{\rm c} cuprates in which each electron dissociates into holon and spinon. Quasiexcitations and resistivity in the PFS state are also studied. The resistivity is just the sum of contributions of chargeons and fluxons, and ρxx\rho_{xx} changes its behavior at T=TPFST = T_{\rm PFS}, reflecting the change of quasiparticles from chargeons and fluxons at T<TPFST < T_{\rm PFS} to electrons at TPFS<TT_{\rm PFS} < T.Comment: 18 pages, 7 figure

    Glucose-6-phosphate-dehydrogenase deficiency as a risk factor in proliferative disorder development

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    Glucose-6-phosphate dehydrogenase (G6PD) is an important site of metabolic control in the pentose phosphate pathway (PPP) which provides reducing power (NADPH) and pentose phosphates. The former is mainly involved in the detoxification of chemical reactive species; the latter in the regulation of cell proliferation. G6PD deficiency is the most common enzymopathy in the human population, characterized by decreased G6PD activity, mainly in red blood cells, but actually also in nucleated cells. This decreased activity is not due to enzyme synthesis impairment, but rather to reduced enzyme stability, which leads to a shortening of its half-life. Therefore, a major problem is to understand the underlying mechanisms linking G6PD deficiency to oxidative stress and cell proliferation. In order to address this issue, in the present study we utilized, as an experimental model, fibroblasts isolated from pterygium, an ocular proliferative lesion, from G6PD normal and deficient (PFs+ and PFs-, respectively) patients. Our choice was determined by the fact that pterygium is believed to be caused by chronic oxidative stress induced by UV exposure, and that pterygium fibroblasts resemble a tumorigenic phenotype. As controls we utilized fibroblasts isolated from conjunctiva from G6PD normal and deficient patients (NCFs+ and NCFs-, respectively) who had undergone cataract surgery. &#xd;&#xa;Growth rate analysis revealed that PFs grow faster than NCFs, but while NCFs- grow more slowly than NCFs+, PFs- and PFs+ grow at the same rate. This was associated with significantly lower G6PD activity in NCFs+ compared to NCFs-, while no significant differences in the G6PD activity of PFs+ and PFs- were noted. This result was supported by the finding that in PFs-, G6PD mRNA levels were significantly higher than in PFs+. Another interesting finding of this study was increased green autofluorescence in both NCFs- and PFs- compared to corresponding positive cells, indicative of pronounced oxidative stress in deficient cells. Finally, abnormal accumulation of neutral lipids, mainly cholesterol esters was observed both in PFs- and PFs+ compared to NCFs- and NCFs+. Though further studies are necessary for better understanding the exact mechanism which links G6PD to oxidative stress and cell proliferation, our data allow to speculate on the role of G6PD on tumorigenesis, and to consider G6PD-deficient subjects at major risk to develop common and dreaded proliferative disorders, such as atherosclerosis and cancer. &#xd;&#xa

    CT-based tumour response criteria compared after combined treatment for liver metastases of colorectal cancer

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    open6noPurpose: The aim of this analysis is to compare different tumour response criteria (TRC) after chemotherapy combined with bevacizumab in liver metastases from colorectal cancer (mCRC) to ascertain the best early prognostic indicator of response. Methods and Materials: 103 target liver metastases from 65 mCRC patients treated with chemoterapy plus bevacizumab were examined at the Istituto Oncologico Veneto IOV-IRCSS (March 2008-January 2013). All patients had baseline CT and at least one follow-up scan. Tumour response was retrospectively analyzed by two radiologists using RECIST1.1, modified Choi, and Chun morphologic criteria. Tumour response, classified as good (complete or partial response) or poor (stable or progressive disease), was compared with progression-free survival (PFS) at first follow-up (t1) and time of best response. Interobserver agreement and concordance between TRC were measured. Results: At t1, 32.31% showed a good response according to RECIST1.1 (median PFS 11.1), 84.62% according to Choi (median PFS 10.8). These percentages rose to 49.23% (median PFS 12.1) and 87.69% (median PFS 10.8), respectively, at the time of best response. According to Chun, 67.69% showed a good response at the time of best response (median PFS 10.8). The Choi criteria detected a higher proportion of good responders at t1, showing a better correlation with PFS; all methods correlated with PFS at the time of best response. Conclusion: The Choi criteria proved more consistent in the early detection of response in mCRC treated with chemotherapy plus bevacizumab, underscoring the importance of using these criteria in the early assessment of response to combined treatment.openopenVarotto, A.; Di Grazia, L.; Aliberti, C.; Bergamo, F.; Nardin, M.; Pomerri, F.Varotto, A.; Di Grazia, L.; Aliberti, C.; Bergamo, F.; Nardin, M.; Pomerri, Fabi

    Toward a numerical deshaker for PFS

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    The Planetary Fourier Spectrometer (PFS) onboard Mars Express (MEx) is the instrument with the highest spectral resolution observing Mars from orbit since January 2004. It permits studying the atmospheric structure, major and minor compounds. The present time version of the calibration is limited by the effects of mechanical vibration, currently not corrected. We proposed here a new approach to correct for the vibrations based on semi-blind deconvolution of the measurements. This new approach shows that a correction can be done efficiently with 85% reduction of the artefacts, in a equivalent manner to the stacking of 10 spectra. Our strategy is not fully automatic due to the dependence on some regularisation parameters. It may be applied on the complete PFS dataset, correcting the large-scale perturbation due to microvibrations for each spectrum independently. This approach is validated on actual PFS data of Short Wavelength Channel (SWC), perturbed by microvibrations. A coherence check can be performed and also validate our approach. Unfortunately, the coherence check can be done only on the first 310 orbits of MEx only, until the laser line has been switch off. More generally, this work may apply to numerically "deshake" Fourier Transform Spectrometer (FTS), widely used in space experiments or in the laboratory.Comment: 18 pages, 8 figures, submitted to Planetary and Space Scienc

    Use of the metastatic breast cancer progression (MBC-P) questionnaire to assess the value of progression-free survival for women with metastatic breast cancer.

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    While overall survival (OS) has historically been the primary endpoint for clinical trials in oncology, progression-free survival (PFS) has gained acceptance as a valuable surrogate endpoint. However, there are no known published reports about the value of PFS from the patient's perspective. We developed a questionnaire that included items regarding quality of life (QoL) and the importance of different treatment outcomes and presented hypothetical scenarios for which respondents were asked to indicate their preferences concerning treatments as they relate to PFS. 282 women with metastatic breast cancer (MBC), ranging in age from 21 to 80 years completed an online version of this questionnaire. The majority of women (66 %) had been diagnosed with MBC within the previous 3 years and 56 % had been told their MBC had progressed. When asked to rank five treatment characteristics from most important to least important, respondents ranked "extending PFS" as the second most important treatment outcome after OS. When presented with a hypothetical scenario of two women receiving different treatments, respondents preferred the treatment that resulted in longer PFS (16 vs. 12 months), even when OS and side effects were assumed to be equal. Specifically, when asked to consider which woman within the hypothetical scenario had better QoL, physical functioning, and emotional well-being, respondents more often chose the woman who experienced longer PFS (QoL: 40 vs. 6 %; physical functioning: 32 vs. 8 %; emotional well-being: 58 vs. 6 %) compared to the woman within the hypothetical scenario who had a shorter time of progression. Respondents rated their own QoL highest after being told their MBC was responding to treatment (mean score 76.6) versus after the initial diagnosis of breast cancer and MBC (68.5 and 60.3). These findings suggest that extending PFS is an important treatment outcome and, from a patient perspective, improves overall QoL, physical functioning, and emotional well-being
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