Yahia Ahmed - Academia.edu (original) (raw)

Papers by Yahia Ahmed

Research paper thumbnail of Measurement and prediction of microshock currents and voltages in an HV laboratory

Microshocks are the low current, continuous discharges experienced by people capacitively coupled... more Microshocks are the low current, continuous discharges experienced by people capacitively coupled to high voltage equipment. The situations in which these discharges occur are complicated by the size and complexity of the high voltage equipment and the sensitivity of the person concerned. A simple model has been constructed in the commercial software package CDEGS. This has been used to model a geometrically simple object designed to represent a person adjacent to a high voltage tower. The predictions of the model are compared to experiments in a high voltage laboratory. The predictions are shown to be extremely accurate and suggest that CDEGS is capable of providing useful predictions in a more realistic scenario.

Research paper thumbnail of Turning administrative systems into information systems

JOURNAL OF OFFICIAL STATISTICS- …, 1993

... Furthermore, this two-fold growth in programs was accompanied by a parallel four-fold increas... more ... Furthermore, this two-fold growth in programs was accompanied by a parallel four-fold increase in the amount of data ... I and II; and Kilss, B. and Alvey, W. (1985), Record Linkage Techniques -- 1985, US Department of the Treasury, Internal ... The Risk of Disclosure for Microdata. ...

Research paper thumbnail of Long-term outcomes of endoscopic submucosal dissection for early gastric cancer: A single-center retrospective study

Digestive Endoscopy, 2013

Background: Colorectal carcinomas (CRCs) arise from premalignant precursors in an adenoma-carcino... more Background: Colorectal carcinomas (CRCs) arise from premalignant precursors in an adenoma-carcinoma sequence, in which adenoma with high-grade dysplasia (HGD) and early-stage carcinoma are defined as advanced neoplasia. A limited number of studies have evaluated the long-term outcomes of endoscopic submucosal dissection (ESD) for advanced colorectal neoplasia. This study aimed to assess the efficacy and safety of ESD for advanced colorectal neoplasia as well as the long-term outcomes, including local recurrence and metastasis. Methods: We analyzed data collected from 610 consecutive patients with 616 advanced colorectal neoplasia lesions treated with ESD between January 2007 and December 2013. Clinical, endoscopic, and histological data were collected over a median follow-up period of 58 months to determine tumor stage and type, resection status, complications, tumor recurrence, and distant metastasis. Results: The overall rates of en bloc resection, histological complete resection, and major complications were 94.3%, 89.4%, and 2.3%, respectively. Hybrid ESD was an independent factor of piecemeal resection. Tumor location in the colon was associated with increased risk of ESD-related complications. During the follow-up period, all patients remained free of metastasis. However, local recurrence occurred in 4 patients (0.8%); piecemeal resection was a risk factor. Conclusions: ESD is effective and safe for resection of advanced colorectal neoplasia, with a high en bloc resection rate and favorable long-term outcomes. ESD is indicated for the treatment of HGD and early-stage CRC to obtain curative resection and reduce local recurrence rate.

Research paper thumbnail of Measurement and prediction of microshock currents and voltages in an HV laboratory

Microshocks are the low current, continuous discharges experienced by people capacitively coupled... more Microshocks are the low current, continuous discharges experienced by people capacitively coupled to high voltage equipment. The situations in which these discharges occur are complicated by the size and complexity of the high voltage equipment and the sensitivity of the person concerned. A simple model has been constructed in the commercial software package CDEGS. This has been used to model a geometrically simple object designed to represent a person adjacent to a high voltage tower. The predictions of the model are compared to experiments in a high voltage laboratory. The predictions are shown to be extremely accurate and suggest that CDEGS is capable of providing useful predictions in a more realistic scenario.

Research paper thumbnail of Turning administrative systems into information systems

JOURNAL OF OFFICIAL STATISTICS- …, 1993

... Furthermore, this two-fold growth in programs was accompanied by a parallel four-fold increas... more ... Furthermore, this two-fold growth in programs was accompanied by a parallel four-fold increase in the amount of data ... I and II; and Kilss, B. and Alvey, W. (1985), Record Linkage Techniques -- 1985, US Department of the Treasury, Internal ... The Risk of Disclosure for Microdata. ...

Research paper thumbnail of Long-term outcomes of endoscopic submucosal dissection for early gastric cancer: A single-center retrospective study

Digestive Endoscopy, 2013

Background: Colorectal carcinomas (CRCs) arise from premalignant precursors in an adenoma-carcino... more Background: Colorectal carcinomas (CRCs) arise from premalignant precursors in an adenoma-carcinoma sequence, in which adenoma with high-grade dysplasia (HGD) and early-stage carcinoma are defined as advanced neoplasia. A limited number of studies have evaluated the long-term outcomes of endoscopic submucosal dissection (ESD) for advanced colorectal neoplasia. This study aimed to assess the efficacy and safety of ESD for advanced colorectal neoplasia as well as the long-term outcomes, including local recurrence and metastasis. Methods: We analyzed data collected from 610 consecutive patients with 616 advanced colorectal neoplasia lesions treated with ESD between January 2007 and December 2013. Clinical, endoscopic, and histological data were collected over a median follow-up period of 58 months to determine tumor stage and type, resection status, complications, tumor recurrence, and distant metastasis. Results: The overall rates of en bloc resection, histological complete resection, and major complications were 94.3%, 89.4%, and 2.3%, respectively. Hybrid ESD was an independent factor of piecemeal resection. Tumor location in the colon was associated with increased risk of ESD-related complications. During the follow-up period, all patients remained free of metastasis. However, local recurrence occurred in 4 patients (0.8%); piecemeal resection was a risk factor. Conclusions: ESD is effective and safe for resection of advanced colorectal neoplasia, with a high en bloc resection rate and favorable long-term outcomes. ESD is indicated for the treatment of HGD and early-stage CRC to obtain curative resection and reduce local recurrence rate.