Study of Charm Production in W Decays

The production rate of charm quark in W decays has been measured at LEP-2 energies with the ALEPH detector. The charm quarks are tagged by using an algorithm based on the kinematic properties of the jets, the number of identified leptons, the energy of fully reconstructed D mesons and on lifetime information

Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

© Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License.The eruption of the Icelandic volcano Eyjafjallaj ökull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5-15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.Peer reviewe

Hereditary palmoplantar keratoderma - phenotypes and mutations in 64 patients

Background Hereditary palmoplantar keratodermas (PPK) represent a heterogeneous group of rare skin disorders with epidermal hyperkeratosis of the palms and soles, with occasional additional manifestations in other tissues. Mutations in at least 69 genes have been implicated in PPK, but further novel candidate genes and mutations are still to be found. Objectives To identify mutations underlying PPK in a cohort of 64 patients. Methods DNA of 48 patients was analysed on a custom-designed in-house panel for 35 PPK genes, and 16 patients were investigated by a diagnostic genetic laboratory either by whole-exome sequencing, gene panels or targeted single-gene sequencing. Results Of the 64 PPK patients, 32 had diffuse (50%), 19 focal (30%) and 13 punctate (20%) PPK. None had striate PPK. Pathogenic mutations in altogether five genes were identified in 31 of 64 (48%) patients, the majority (22/31) with diffuse PPK. Of them, 11 had a mutation in AQP5, five in SERPINB7, four in KRT9 and two in SLURP1. AAGAB mutations were found in nine punctate PPK patients. New mutations were identified in KRT9 and AAGAB. No pathogenic mutations were detected in focal PPK. Variants of uncertain significance (VUS) in PPK-associated and other genes were observed in 21 patients that might explain their PPK. No suggestive pathogenic variants were found for 12 patients. Conclusions Diffuse PPK was the most common (50%) and striate PPK was not observed. We identified pathogenic mutations in 48% of our PPK patients, mainly in five genes: AQP5, AAGAB, KRT9, SERPINB7 and SLURP1.Peer reviewe

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

Search for the glueball candidates f0(1500) and fJ(1710) in gamma gamma collisions

Data taken with the ALEPH detector at LEP1 have been used to search for gamma gamma production of the glueball candidates f0(1500) and fJ(1710) via their decay to pi+pi-. No signal is observed and upper limits to the product of gamma gamma width and pi+pi- branching ratio of the f0(1500) and the fJ(1710) have been measured to be Gamma_(gamma gamma -> f0(1500)). BR(f0(1500)->pi+pi-) < 0.31 keV and Gamma_(gamma gamma -> fJ(1710)). BR(fJ(1710)->pi+pi-) < 0.55 keV at 95% confidence level.Comment: 10 pages, 3 figure

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

Local Microenvironment Provides Important Cues for Cell Differentiation in Lingual Epithelia

Transgenic Keratin14-rtTA-PTR mice specifically express Keratin14 (K14) in the tongue epithelia, as well as co-express EGFP and the dominant negative ΔTgfbr2 genes upon treatment with Doxycycline (Dox). As TGF-β signaling negatively regulates the stem cell cycle and proliferation, its disruption by Dox induction in these transgenic mice shortens the cell cycle and allows observation of the final fate of those mutated cell lineages within a short period of time. Here, we used inducible transgenic mice to track the K14+ cells through the cell migration stream by immunohistochemical an immunofluorescent imaging. We showed that these cells have different development patterns from the tip to posterior of the tongue, achieved presumably by integrating positional information from the microenvironment. The expression of the K14 gene was variable, depending on the location of the tongue and papillae. Disruption of TGF-β signaling in K14+ progenitor cells resulted in proliferation of stem cell pools

Analysis of c-KIT expression and KIT gene mutation in human mucosal melanomas

Recent data suggested an increased frequency of KIT aberrations in mucosal melanomas, whereas c-KIT in most types of cutaneous melanomas does not appear to be of pathogenetic importance. However, studies investigating the status of the KIT gene in larger, well-characterised groups of patients with mucosal melanomas are lacking. We analysed 44 archival specimens of 39 well-characterised patients with mucosal melanomas of different locations. c-KIT protein expression was determined by immunhistochemistry, KIT gene mutations were analysed by PCR amplification and DNA sequencing of exons 9, 11, 13, 17 and 18. c-KIT protein expression could be shown in 40 out of 44 (91%) tumours in at least 10% of tumour cells. DNA sequence analysis of the KIT was successfully performed in 37 patients. In 6 out of 37 patients (16%) KIT mutations were found, five in exon 11 and one in exon 18. The presence of mutations in exon 11 correlated with a significant stronger immunohistochemical expression of c-KIT protein (P=0.015). Among the six patients with mutations, in two patients the primary tumour was located in the head/neck region, in three patients in the genitourinary tract and in one patient in the anal/rectal area. In conclusion, KIT mutations can be found in a subset of patients with mucosal melanomas irrespective of the location of the primary tumour. Our data encourage therapeutic attempts with tyrosine kinase inhibitors blocking c-KIT in these patients

Bcr/Abl Interferes with the Fanconi Anemia/BRCA Pathway: Implications in the Chromosomal Instability of Chronic Myeloid Leukemia Cells

Chronic myeloid leukemia (CML) is a malignant clonal disorder of the hematopoietic system caused by the expression of the BCR/ABL fusion oncogene. Although it is well known that CML cells are genetically unstable, the mechanisms accounting for this genomic instability are still poorly understood. Because the Fanconi anemia (FA) pathway is believed to control several mechanisms of DNA repair, we investigated whether this pathway was disrupted in CML cells. Our data show that CML cells have a defective capacity to generate FANCD2 nuclear foci, either in dividing cells or after DNA damage. Similarly, human cord blood CD34+ cells transduced with BCR/ABL retroviral vectors showed impaired FANCD2 foci formation, whereas FANCD2 monoubiquitination in these cells was unaffected. Soon after the transduction of CD34+ cells with BCR/ABL retroviral vectors a high proportion of cells with supernumerary centrosomes was observed. Similarly, BCR/ABL induced a high proportion of chromosomal abnormalities, while mediated a cell survival advantage after exposure to DNA cross-linking agents. Significantly, both the impaired formation of FANCD2 nuclear foci, and also the predisposition of BCR/ABL cells to develop centrosomal and chromosomal aberrations were reverted by the ectopic expression of BRCA1. Taken together, our data show for the first time a disruption of the FA/BRCA pathway in BCR/ABL cells, suggesting that this defective pathway should play an important role in the genomic instability of CML by the co-occurrence of centrosomal amplification and DNA repair deficiencies