Alternative antibody for the detection of CA19-9 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access (R) GI Monitor assay on the UniCel (R) Dxl 800 Immunoassay System

Background: Gastrointestinal cancer antigen CA19-9 is known as a valuable marker for the management of patients with pancreatic cancer. Methods: The analytical and clinical performance of the Access(R) GI Monitor assay (Beckman Coulter) was evaluated on the UniCel(R) Dxl 800 Immunoassay System at five different European sites and compared with a reference method, defined as CA19-9 on the Elecsys System (Roche Diagnostics). Results: Total imprecision (%CV) of the GI Monitor ranged between 3.4% and 7.7%, and inter-laboratory reproducibility between 3.6% and 4.0%. Linearity upon dilution showed a mean recovery of 97.4% (SD+7.2%). Endogenous interferents had no influence on GI Monitor levels (mean recoveries: hemoglobin 103%, bilirubin 106%, triglycerides 106%). There was no high-dose hook effect up to 115,000 kU/L. Clinical performance investigated in sera from 1811 individuals showed a good correlation between the Access' GI Monitor and Elecsys CA19-9 (R = 0.959, slope = 1.004, intercept +0.17). GI Monitor serum levels were low in healthy individuals (n = 267, median = 6.0 kU/L, 95th percentile = 23.1 kU/L), higher in individuals with various benign diseases (n = 550, medians = 5.8-13.4 kU/L, 95th percentiles = 30.1-195.5 kU/L) and even higher in individuals suffering from various cancers (n = 995, medians = 8.4-233.8 kU/L, 95th percentiles = 53.7-13,902 kU/L). Optimal diagnostic accuracy for cancer detection against the relevant benign control group by the GI Monitor was found for pancreatic cancer {[}area under the curve (AUC) 0.83]. Results for the reference CA19-9 assay were comparable (AUC 0.85). Conclusions: The Access(R) GI Monitor provides very good methodological characteristics and demonstrates an excellent analytical and clinical correlation with the Elecsys CA19-9. The GI Monitor shows the best diagnostic accuracy in pancreatic cancer. Our results also suggest a clinical value of the GI Monitor in other cancers

Using Synchronic and Diachronic Relations for Summarizing Multiple Documents Describing Evolving Events

In this paper we present a fresh look at the problem of summarizing evolving events from multiple sources. After a discussion concerning the nature of evolving events we introduce a distinction between linearly and non-linearly evolving events. We present then a general methodology for the automatic creation of summaries from evolving events. At its heart lie the notions of Synchronic and Diachronic cross-document Relations (SDRs), whose aim is the identification of similarities and differences between sources, from a synchronical and diachronical perspective. SDRs do not connect documents or textual elements found therein, but structures one might call messages. Applying this methodology will yield a set of messages and relations, SDRs, connecting them, that is a graph which we call grid. We will show how such a grid can be considered as the starting point of a Natural Language Generation System. The methodology is evaluated in two case-studies, one for linearly evolving events (descriptions of football matches) and another one for non-linearly evolving events (terrorist incidents involving hostages). In both cases we evaluate the results produced by our computational systems.Comment: 45 pages, 6 figures. To appear in the Journal of Intelligent Information System

The role of relatives in decisions concerning life-prolonging treatment in patients with end-stage malignant disorders: informants, advocates or surrogate decision-makers?

Background: This study examines the extent to which relatives of severely ill cancer patients are involved in the decision to limit treatment (DLT), their role in communicating patient wishes and the incidence of and reasons for disagreement with relatives. Patients and methods: This cohort study followed 70 patients with terminal cancer, for whom a limitation of life-prolonging treatment was being considered. ‘Embedded researchers' recorded patients' wishes and the relatives' roles and disagreements with DLT. Results: Although 63 out of 70 patients had relatives present during their care, only 32% of relatives were involved in DLT. Physicians were more likely to know the end-of-life (EOL) preferences for those patients who had visiting relatives than those without them (78% versus 29%, P = 0.014). Most relatives supported patients in voicing their preferences (68%), but one-third acted against the known or presumed wishes of patients (32%). Disagreements with patients' relatives occurred in 21% of cases, and predominantly when relatives held views that contradicted known patient preferences (71% versus 7%, P = 0.001). Conclusion: If relatives are to play an important part in EOL decision making, we must devise strategies to recognise their potential as patients' advocates as well as their own need

On the magnetic nature of electron transport barriers in tokamaks

The formation of internal transport barriers in the vicinity of rational magnetic surfaces in tokamaks with braided magnetic fields is studied for a simplified model of the perturbed magnetic field with a broad spatial spectrum and a monotonous shear profile. The island overlap criterion is used to derive a condition for barrier formation. This condition links the amplitude and the spectral width of the perturbation with the shear parameter. Numerical experiments with the MHD Monte-Carlo code E3D, where the problem of plasma heat conductivity is solved in 3D, confirm this formation of transport barriers in the case of a monotonous shear profile. Assuming that experimentally observed electron internal transport barriers are the result of local reduction of electron heat transport due to the magnetic field braiding, the amplitude and spectral width of magnetic perturbations are estimated for the tokamak RTP

Impact of phonons on dephasing of individual excitons in deterministic quantum dot microlenses

Optimized light-matter coupling in semiconductor nanostructures is a key to understand their optical properties and can be enabled by advanced fabrication techniques. Using in-situ electron beam lithography combined with a low-temperature cathodoluminescence imaging, we deterministically fabricate microlenses above selected InAs quantum dots (QDs) achieving their efficient coupling to the external light field. This enables to perform four-wave mixing micro-spectroscopy of single QD excitons, revealing the exciton population and coherence dynamics. We infer the temperature dependence of the dephasing in order to address the impact of phonons on the decoherence of confined excitons. The loss of the coherence over the first picoseconds is associated with the emission of a phonon wave packet, also governing the phonon background in photoluminescence (PL) spectra. Using theory based on the independent boson model, we consistently explain the initial coherence decay, the zero-phonon line fraction, and the lineshape of the phonon-assisted PL using realistic quantum dot geometries

Hole motion in an arbitrary spin background: Beyond the minimal spin-polaron approximation

The motion of a single hole in an arbitrary magnetic background is investigated for the 2D t-J model. The wavefunction of the hole is described within a generalized string picture which leads to a modified concept of spin polarons. We calculate the one-hole spectral function using a large string basis for the limits of a Neel ordered and a completely disordered background. In addition we use a simple approximation to interpolate between these cases. For the antiferromagnetic background we reproduce the well-known quasiparticle band. In the disordered case the shape of the spectral function is found to be strongly momentum-dependent, the quasiparticle weight vanishes for all hole momenta. Finally, we discuss the relevance of results for the lowest energy eigenvalue and its dispersion obtained from calculations using a polaron of minimal size as found in the literature.Comment: 13 pages, 8 figures, to appear in Phys. Rev.

Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions

For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A^2\Delta - X^2\Pi Ger\"o band around 430 nm. The CH A-level can be excited either by electron-impact or by dissociative recombination (D.R.) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by D.R. dominates at T_e < 1.5 eV. The results indicate that the fraction of D.R. events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by electron impact de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at n_e=1.3*10^20 m^-3, to 2.8 at n_e=9.3*10^20 m^-3. Its inclusion significantly improved agreement between experiment and modeling