Development of innovative micropattern gaseous detectors with resistive electrodes and first results of their applications

The paper summarizes our latest progress in the development of newly introduced micro pattern gaseous detectors with resistive electrodes. These resistive electrodes protect the detector and the front-end electronics in case of occasional discharges and thus make the detectors very robust and reliable in operation. As an example, we describe in greater detail a new recently developed GEM-like detector, fully spark-protected with electrodes made of resistive kapton. We discovered that all resistive layers used in these studies (including kapton), that are coated with photosensitive layers, such as CsI, can be used as efficient photo cathodes for detectors operating in a pulse counting mode. We describe the first applications of such detectors combined with CsI or SbCs photo cathodes for the detection of UV photons at room and cryogenic temperatures.Comment: Presented at the 11 Vienna Conference on Instrumentation, February, 200

Study of GEM-like detectors with resistive electrodes for RICH applications

We have developed prototypes of GEM-like detectors with resistive electrodes to be used as RICH photodetectors equipped with CsI photocathodes. The main advantages of these detectors are their intrinsic spark protection and possibility to operate at high gain (~10E5) in many gases including poorly quenched ones, allowing for the adoption of windowless configurations in which the radiator gas is also used in the chamber. Results of systematic studies of the resistive GEMs combined with CsI photocathodes are presented: its quantum efficiency, rate characteristics, long-term stability, etc. On the basis of the obtained results, we believe that the new detector will be a promising candidate for upgrading the ALICE RICH detectorComment: Presented at the International Workshop RICH-2007, Trieste, Italy, October 200

A New GEM-like Imaging Detector with Electrodes Coated with Resistive Layers

We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers: CuO or CrO. These detectors can operate stably at gains close to 10E5 and they are very robust. We discovered that the cathodes of these detectors could be coated by CsI layers and in such a way the detectors gain high efficiency for the UV photons. We also demonstrated that such detectors can operate stably in the cascade mode and high overall gains (~10E6) are reachable. This opens applications in several areas, for example in RICH or in noble liquid TPCs. Results from the first applications of these devices for UV photon detection at room and cryogenic temperatures are given.Comment: Presented at the IEEE Nuclear Science Symposium, San Diego, California, October 200

Development and first tests of GEM-like detectors with resistive electrodes

We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers or completely made of resistive materials. These detectors can operate stably at gains close to 105. The resistive layers limit the energy of discharges appearing at higher gains thus making the detectors very robust. We demonstrated that the cathodes of some of these detectors could be coated by CsI or SbCs layers to enhance the detection efficiency for the UV and visible photons. We also discovered that such detectors can operate stably in the cascade mode and high overall gains ($~10^{6}$) are reachable. Applications in several areas, for example in RICH or in noble liquid TPCs are therefore possible. The first results from the detection of UV photons at room and cryogenic temperatures will be given

THGEM-based detectors for sampling elements in DHCAL: laboratory and beam evaluation

We report on the results of an extensive R&D program aimed at the evaluation of Thick-Gas Electron Multipliers (THGEM) as potential active elements for Digital Hadron Calorimetry (DHCAL). Results are presented on efficiency, pad multiplicity and discharge probability of a 10x10 cm2 prototype detector with 1 cm2 readout pads. The detector is comprised of single- or double-THGEM multipliers coupled to the pad electrode either directly or via a resistive anode. Investigations employing standard discrete electronics and the KPiX readout system have been carried out both under laboratory conditions and with muons and pions at the CERN RD51 test beam. For detectors having a charge-induction gap, it has been shown that even a ~6 mm thick single-THGEM detector reached detection efficiencies above 95%, with pad-hit multiplicity of 1.1-1.2 per event; discharge probabilities were of the order of 1e-6 - 1e-5 sparks/trigger, depending on the detector structure and gain. Preliminary beam tests with a WELL hole-structure, closed by a resistive anode, yielded discharge probabilities of <2e-6 for an efficiency of ~95%. Methods are presented to reduce charge-spread and pad multiplicity with resistive anodes. The new method showed good prospects for further evaluation of very thin THGEM-based detectors as potential active elements for DHCAL, with competitive performances, simplicity and robustness. Further developments are in course.Comment: 15 pages, 11 figures, MPGD2011 conference proceedin

Influence of proinflammatory cytokines on membrane rigidity and morphofunctional state of circulating neutrophils in ovarian tumors

Priming and activation mediated by cytokines cause transient reactions of actin polymerization in neutrophils (Nph), expansion and softening of cells, changes in receptor status, phagocytic ability, and generation of extracellular traps (NET), thus ultimately determining pro- or antitumor phenotype of Nph. To assess the effects of pro-inflammatory cytokines on membrane rigidity and morphofunctional state of neutrophils in benign tumors and ovarian cancer, the levels of circulating cytokines (IL-2, IL-18, MCP-1, TIMP-1), expression of adhesion markers (CD11b), degranulation (CD63), as well as FcãRIIIb receptors promoting phagocytosis (CD16). Ability of neutrophils to phagocytosis and the formation of NET was determined. Statistical evaluation of the data obtained was carried out using Statistica 13.0, Jamovi 1.6.5.0 software. An increase in membrane rigidity was found in benign and malignant ovarian tumors. In benign ovarian tumors, phagocytic activity and expression of CD11b were enhanced. In ovarian cancer, the number of CD11b+Nph and CD63+Nph were increased. Meaanwhile, at initial cancer stage, the ability to form NET predominates, and phagocytic activity increases with advancing ovarian cancer. Serum MCP-1 levels are elevated in benign tumors and at all stages of ovarian cancer. IL-2 is elevated at early stage and in advanced ovarian cancer. The level of IL-18 and TIMP-1 in the serum of patients with benign ovarian tumor did not differ significantly from the norm. Using multiple regression approach, the dependence of neutrophil membrane rigidity on the levels of circulating IL-2, TIMP-1, MCP-1, IL-18 was revealed in benign ovarian tumors, and a direct correlation was found between the neutrophil membrane rigidity and CD11b expression. Only IL-2 was associated with neutrophil membrane rigidity in ovarian cancer. At the same time, the rigidity of the neutrophil membrane directly correlated with CD16, CD63, expression like as with phagocytic index and inversely correlates with the number of traps. A combination of IL-2, MCP-1 and membrane rigidity of circulating neutrophils (based on multivariate analysis) could be used for differential diagnosis of ovarian cancer. Thus, in a benign ovarian tumor, circulating proinflammatory cytokines are associated with increased rigidity of neutrophil membrane and increase in their adhesion capacity. In ovarian cancer, only IL-2 is associated with altered rigidity of circulating neutrophils. Increase of the latter index is accompanied by elevated phagocytic activity and decreased ability to form NET

Phenotype of circulating neutrophils at different stages of cervical neoplasia

At the present time, there is no common point of view to the role of circulating neutrophils (NP) in emergence and development of neoplasia. It is suggested that due to high functional plasticity, the neutrophils may exhibit both pro- and antitumor activity. In order to study the NP phenotype at different stages of cervical neoplasia (CN), we have evaluated their absolute and relative amounts, myeloperoxidase activity, spontaneous and induced NST-test markers, and the level of intracellular cationic proteins. Spontaneous production of elastase and active forms of matrix metalloproteinases, the levels of IL-2, IL-8, IL-18, IFNy, G-CSF were determined in the NP cell lysates and in blood serum. The formation of extracellular traps (NET) was evaluated using 1-day cultures of Saccharomyces cerevisiae as an inducer. We examined 31 patients with cervical intraepithelial neoplasia (CIN) and 21 primary patients with cervical cancer (CC, Ia stage according to FIGO scale), as well as 25 practically healthy women. We revealed increased spontaneous and inducible oxygen-dependent cytolytic and phagocytic activity and spontaneous production of NET if compared to normal values, along with decreased absolute NP numbers in patients with CIN, thus suggesting the antitumor activity of NP. The levels of “pro-tumor” cytokines (MMP-9, IL-2 and G-CSF) become increased over normal levels as early as at the CIN stage, both for the neutrophils and blood plasma. High levels of regulatory IFNy and neutrophil-priming IL-8 in blood plasma do not presume any use of exogenous NP-activating factors at the stage of cervical dysplasia. At the initial stage of cervical cancer, the absolute NP amounts are significantly increased compared to normal counts. However, despite increased spontaneous oxygen-dependent cytolytic activity, the NPs have a significantly reduced activity of phagocytosis and sharply increased spontaneous production of NET, thus, generally, being characteristic to the “pro-tumorous” NP phenotype. IL-2 levels are elevated, and MMP-9 values are still increased in NP and blood plasma of patients with CC (stage Ia). Hence, the obtained results suggest some changes of NP phenotype to a pro-tumorous pattern during transition from intraepithelial dysplasia to cervical cancer. These results allowed us to design an algorithm for examining women with suspected cervical cancer, including IL-2 measurement in blood serum, and MMP-9 amounts in the NP lysates

Charge separation relative to the reaction plane in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}= 2.76 TeV

Measurements of charge dependent azimuthal correlations with the ALICE detector at the LHC are reported for Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV. Two- and three-particle charge-dependent azimuthal correlations in the pseudo-rapidity range $|\eta| < 0.8$ are presented as a function of the collision centrality, particle separation in pseudo-rapidity, and transverse momentum. A clear signal compatible with a charge-dependent separation relative to the reaction plane is observed, which shows little or no collision energy dependence when compared to measurements at RHIC energies. This provides a new insight for understanding the nature of the charge dependent azimuthal correlations observed at RHIC and LHC energies.Comment: 12 pages, 3 captioned figures, authors from page 2 to 6, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/286

A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio