231 research outputs found
Immediate vaginal reconstruction following pelvic exenteration using the pedicled vertical Deep Inferior Epigastric Perforator (DIEP) flap: A technical note
La reconstruction vaginale immédiate est généralement réalisée à la suite d'une exentération pelvienne pour cancer du col de l'utérus, en cas de récidive (après radiothérapie) ou de fistules radiques sévères. Le prélèvement des lambeaux sur des vaisseaux perforants, tels que le lambeau perforant basé sur le pédicule épigastrique inférieur (DIEP), permet d'obtenir des tissus viables pour la reconstruction vaginale et est associé à une réduction de la morbidité du site donneur. Ce rapport décrit la technique chirurgicale, qui est l'une des procédures de choix pour la reconstruction vaginale. Il s'agit d'une technique fiable et avantageuse, en particulier chez les femmes pour qui il ne restait plus que l'option de l'exentération en cas d’échec de l'irradiation
Earnings management and audit quality:stakeholders’ perceptions
This paper examines the perceptions of Libyan Commercial Banks’ (LCBs) stakeholders regarding the role of the external auditor in relation to earnings management (EM). A total of 28 semi-structured interviews were carried out with a range of LCB stakeholders comprising preparers of financial statements, users, regulators and academics. A questionnaire survey of stakeholders which yielded 102 Responses (response rate 53%) was also carried out. A variety of views were held which varied to some extent according to stakeholder group. A widely held perception amongst interviewees was that the auditor has the ability to detect EM practices but may not be able to prevent it. However questionnaire respondents were, in aggregate, more confident of the auditor’s ability to deter EM due to the influence of the audit report. The paper provides insights into stakeholders’ perceptions of the quality of bank audits. The findings are of particular relevance to regulators, and specifically, the Central Bank of Libya. Perceptions of audit quality raise questions about its guidance and regulations especially in connection with audit firm rotation. Perceptions of audit quality, and therefore, of the credibility of financial statements should be of interest to all stakeholders. The importance of the banking sector for society has been amply demonstrated in recent years. A well-functioning audit function is a key component of its regulation. To the best of our knowledge, this paper is the first to examine issues related to banks’ audit quality and audit firm rotation in Libya
FENDL: A library for fusion research and applications
The Fusion Evaluated Nuclear Data Library (FENDL) is a comprehensive and
validated collection of nuclear cross section data coordinated by the
International Atomic Energy Agency (IAEA) Nuclear Data Section (NDS). FENDL
assembles the best nuclear data for fusion applications selected from available
nuclear data libraries and has been under development for decades. FENDL
contains sub-libraries for incident neutron, proton, and deuteron cross
sections including general purpose and activation files used for particle
transport and nuclide inventory calculations.
We describe the history, selection of evaluations for the various
sub-libraries (neutron, proton, deuteron) with the focus on transport and
reactor dosimetry applications, the processing of the nuclear data for
application codes, and the development of the TENDL-2017 library which is the
currently recommended activation library for FENDL. We briefly describe the
IAEA IRDFF library as the recommended library for dosimetry fusion
applications. We also present work on validation of the neutron sub-library
using a variety of fusion relevant computational and experimental benchmarks. A
variety of cross section libraries are used for the validation work including
FENDL-2.1, FENDL-3.1d, FENDL-3.2, ENDF/B-VIII.0, and JEFF-3.2 with the emphasis
on the FENDL libraries. The results of the experimental validation showed that
the performance of FENDL-3.2b is at least as good and in most cases better than
FENDL-2.1.
Future work will consider improved evaluations developed by the International
Nuclear Data Evaluation Network (INDEN). Additional work will be needed to
investigate differences in gas production in structural materials. Covariance
matrices need to be updated to support the development of fusion technology.
Additional validation work for high-energy neutrons, protons and deuterons, and
the activation library will be needed.Comment: 81 pages, 114 figure
Aberrant Epigenetic Silencing Is Triggered by a Transient Reduction in Gene Expression
Aberrant epigenetic silencing plays a major role in cancer formation by inactivating tumor suppressor genes. While the endpoints of aberrant silencing are known, i.e., promoter region DNA methylation and altered histone modifications, the triggers of silencing are not known. We used the tet-off system to test the hypothesis that a transient reduction in gene expression will sensitize a promoter to undergo epigenetic silencing.The tet responsive promoter (P(TRE)) was used to drive expression of the selectable human HPRT cDNA in independent transfectants of an Hprt deficient mouse cell line. In this system, high basal HPRT expression is greatly reduced when doxycycline (Dox) is added to the culture medium. Exposure of the P(TRE)-HPRT transfectants to Dox induced HPRT deficient clones in a time dependent manner. A molecular analysis demonstrated promoter region DNA methylation, loss of histone modifications associated with expression (i.e., H3 lysine 9 and 14 acetylation and lysine 4 methylation), and acquisition of the repressive histone modification H3 lysine 9 methylation. These changes, which are consistent with aberrant epigenetic silencing, were not present in the Dox-treated cultures, with the exception of reduced H3 lysine 14 acetylation. Silenced alleles readily reactivated spontaneously or after treatment of cells with inhibitors of histone deacetylation and/or DNA methylation, but re-silencing of reactivated alleles did not require a new round of Dox exposure. Inhibition of histone deacetylation inhibited both the induction of silencing and re-silencing, whereas inhibition of DNA methylation had no such effect.This study demonstrates that a transient reduction in gene expression triggers a pathway for aberrant silencing in mammalian cells and identifies histone deacetylation as a critical early step in this process. DNA methylation, in contrast, is a secondary step in the silencing pathway under study. A model to explain these observations is offered
Heterochromatin Protein 1β (HP1β) has distinct functions and distinct nuclear distribution in pluripotent versus differentiated cells
Background: Pluripotent embryonic stem cells (ESCs) have the unique ability to differentiate into every cell type and to self-renew. These characteristics correlate with a distinct nuclear architecture, epigenetic signatures enriched for active chromatin marks and hyperdynamic binding of structural chromatin proteins. Recently, several chromatin-related proteins have been shown to regulate ESC pluripotency and/or differentiation, yet the role of the major heterochromatin proteins in pluripotency is unknown. Results: Here we identify Heterochromatin Protein 1β (HP1β) as an essential protein for proper differentiation, and, unexpectedly, for the maintenance of pluripotency in ESCs. In pluripotent and differentiated cells HP1β is differentially localized and differentially associated with chromatin. Deletion of HP1β, but not HP1aα, in ESCs provokes a loss of the morphological and proliferative characteristics of embryonic pluripotent cells, reduces expression of pluripotency factors and causes aberrant differentiation. However, in differentiated cells, loss of HP1β has the opposite effect, perturbing maintenance of the differentiation state and facilitating reprogramming to an induced pluripotent state. Microscopy, biochemical fractionation and chromatin immunoprecipitation reveal a diffuse nucleoplasmic distribution, weak association with chromatin and high expression levels for HP1β in ESCs. The minor fraction of HP1β that is chromatin-bound in ESCs is enriched within exons, unlike the situation in differentiated cells, where it binds heterochromatic satellite repeats and chromocenters. Conclusions: We demonstrate an unexpected duality in the role of HP1β: it is essential in ESCs for maintaining pluripotency, while it is required for proper differentiation in differentiated cells. Thus, HP1β function both depends on, and regulates, the pluripotent state
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