A breakdown voltage model for implanted resurf p-LDMOS device on n+ buried layer

This paper presents an analytical expression of the breakdown voltage of a high voltage implanted RESURF p-LDMOS device which uses the n+ buried layer as an effective device substrate. In this model, the doping profile of the buried layer is considered and discussed. The implant dose for the drift region to implement the RESURF principle is also described by this model. Results calculated from this model are verified by experimental values

High voltage implanted RESURF p-LDMOS using BICMOS technology

The hgh voltage DMOST based on BICMOS technology[l] are becoming more attractive because of its easy integration with bipolar and CMOS devices. Its process is required to be as compatible as possible with the BICMOS technology. This paper presents a complementary RESURF[2] p-LDMOS in whch the ni buried layer is used for the first time, as an effective substrate and the field implant is introduced to modify the drift charges. The implant conditions in t h ~ csa se, particularly the placements, will be studied

Women undergoing endovascular thoracoabdominal aortic aneurysm repair differ significantly from their male counterparts preoperatively and postoperatively

OBJECTIVE: A rational approach to the management of aortic aneurysm disease relies on weighing the risk of aneurysm rupture against the complications and durability of operative repair. In men, seminal studies of infrarenal aortic aneurysm disease and its endovascular management can provide a reasoned argument for the timing and modality of surgery, which is then extrapolated to the management of thoracoabdominal aortic aneurysms (TAAAs). In contrast, there is less appreciation for the natural history of TAAA disease in women and its response to therapy. METHODS: We used a retrospective cohort design of women, all men, and matched men, fit for complex endovascular thoracoabdominal aneurysm repair at two large aortic centers. We controlled for preoperative anatomic and comorbidity differences, and assessed technical success, postoperative renal dysfunction, spinal ischemia, and early mortality. Women and matched men were reassessed at follow-up for long-term durability and survival. RESULTS: Assessing women and all men undergoing complex endovascular aortic reconstruction, we demonstrate that these groups are dissimilar before the intervention with respect to comorbidities, aneurysm extent, and aneurysm size; women have a higher proportion of proximal Crawford extent 1, 2, and 3 aneurysms. Matching men and women for demographic and anatomic differences, we find persistent elevated perioperative mortality in women (16%) undergoing endovascular thoracoabdominal aneurysm repair compared with matched men (6%); however, at the 3-year follow-up, both groups have the same survival. Furthermore, women demonstrate more favorable anatomic responses to aneurysm exclusion, with good durability and greater aneurysm sac regression at follow-up, compared with matched men. CONCLUSIONS: Women and unmatched men with TAAA disease differ preoperatively with respect to aneurysm extent and comorbidities. Controlling for these differences, after complex endovascular aneurysm repair, there is increased early mortality in women compared with matched men. These observations argue for a careful risk stratification of women undergoing endovascular thoracoabdominal aneurysm treatment, balanced with women's good long-term survival and durability of endovascular aneurysm repair

Burnout, well-being and defensive medical practice among obstetricians and gynaecologists in the UK: cross-sectional survey study

Objectives: To determine the prevalence of burnout in doctors practising obstetrics and gynaecology, and assess the association with defensive medical practice and self-reported wellbeing. Design: Nationwide online cross-sectional survey study; December 2017-March 2018. Setting: Hospitals in the United Kingdom Participants: 5661 practising Obstetrics and Gynaecology consultants, specialty and associate specialist doctors and trainees registered with the Royal College of Obstetricians and Gynaecologists Primary and Secondary Outcome Measures: Prevalence of burnout using the Maslach Burnout Inventory and defensive medical practice (avoiding cases or procedures, overprescribing, over-referral) using a 12-item questionnaire. The odds ratios of burnout with defensive medical practice and self-reported wellbeing. Results: 3102/5661 doctors (55%) completed the survey. 3073/3102 (99%) met the inclusion criteria (1462 consultants, 1357 trainees and 254 specialty and associate specialist doctors). 1116/3073 (36%) doctors met the burnout criteria, with levels highest amongst trainees (580/1357 [43%]). 258/1116 (23%) doctors with burnout reported increased defensive practice compared to 142/1957 (7%) without (adjusted odds ratio 4.35, 95% CI 3.46 to 5.49). Odds ratios of burnout with wellbeing items varied between 1.38 and 6.37, and were highest for anxiety (3.59, 95% CI 3.07 to 4.21), depression (4.05, 95% CI 3.26 to 5.04), and suicidal thoughts (6.37, 95% CI 95% CI 3.95 to 10.7). In multivariable logistic regression, being of younger age, white or ‘other’ ethnicity, and graduating with a medical degree from the UK or Ireland had the strongest associations with burnout. Conclusions: High levels of burnout were observed in obstetricians and gynaecologists and particularly amongst trainees. Burnout was associated with both increased defensive medical practice and worse doctor wellbeing. These findings have implications for the wellbeing and retention of doctors as well as the quality of patient care, and may help to inform the content of future interventions aimed at preventing burnout and improving patient safety

Evaluation of clinical prediction models (part 3): calculating the sample size required for an external validation study

An external validation study evaluates the performance of a prediction model in new data, but many of these studies are too small to provide reliable answers. In the third article of their series on model evaluation, Riley and colleagues describe how to calculate the sample size required for external validation studies, and propose to avoid rules of thumb by tailoring calculations to the model and setting at hand

Minimum sample size for developing a multivariable prediction model using multinomial logistic regression.

AIMS: Multinomial logistic regression models allow one to predict the risk of a categorical outcome with > 2 categories. When developing such a model, researchers should ensure the number of participants (n) is appropriate relative to the number of events (Ek) and the number of predictor parameters (pk) for each category k. We propose three criteria to determine the minimum n required in light of existing criteria developed for binary outcomes. PROPOSED CRITERIA: The first criterion aims to minimise the model overfitting. The second aims to minimise the difference between the observed and adjusted R2 Nagelkerke. The third criterion aims to ensure the overall risk is estimated precisely. For criterion (i), we show the sample size must be based on the anticipated Cox-snell R2 of distinct 'one-to-one' logistic regression models corresponding to the sub-models of the multinomial logistic regression, rather than on the overall Cox-snell R2 of the multinomial logistic regression. EVALUATION OF CRITERIA: We tested the performance of the proposed criteria (i) through a simulation study and found that it resulted in the desired level of overfitting. Criterion (ii) and (iii) were natural extensions from previously proposed criteria for binary outcomes and did not require evaluation through simulation. SUMMARY: We illustrated how to implement the sample size criteria through a worked example considering the development of a multinomial risk prediction model for tumour type when presented with an ovarian mass. Code is provided for the simulation and worked example. We will embed our proposed criteria within the pmsampsize R library and Stata modules

Treatment of steroid-induced elevated intraocular pressure with anecortave acetate: a randomized clinical trial.

PURPOSE: The present study is the first randomized clinical trial designed to evaluate the intraocular pressure (IOP)-lowering effect of anecortave acetate (AA) administered at 3 doses (3, 15, or 30 mg) as an anterior juxtascleral depot (AJD) in patients experiencing elevated IOP due to corticosteroid therapy. METHODS: This was a double-masked, randomized, placebo-controlled, multicenter, parallel group trial. Eligible patients had an IOP of at least 24 mmHg and an IOP increase of at least 10 mmHg relative to their IOP before treatment with steroids. A target IOP was established for each patient at baseline. Patients were randomized to 1 of the 4 treatment groups: vehicle, 3 mg AA, 15 mg AA, or 30 mg AA. All patients then received a 0.5 mL AJD of the assigned treatment. Patients returned for scheduled examination visits at weeks 1, 2, 4, 6, months 3, 4, 5, and 6. IOP was measured at each visit as well as best corrected visual acuity (logMAR), ocular motility, eyelid responsiveness, slit lamp examination, and assessment of any adverse events. In addition, at baseline and at exit, a dilated fundus examination was carried out and the lens was examined using LOCS II criteria. RESULTS: Seventy patients were randomized to treatment. At week 4, eyes in the vehicle group showed a 3.4 mmHg (9.1%) decrease from baseline. Reductions for the 3 mg AA (3.1 mmHg, 10.7%) and the 30 mg AA groups (5.4 mmHg, 16.6%) were not significantly different than for vehicle control. However, IOP for the 15 mg AA group at week 4 was reduced 11.5 mmHg (31.3%) from baseline, which was statistically significant (P=0.0487). The mean time to treatment failure was 32.2, 38.9, 56.3, and 32.6 days for the vehicle, 3 mg AA, 15 mg AA, and 30 mg AA groups, respectively. Adverse events were assessed at each post-treatment visit. There were no serious adverse events that were determined to be related to the test article or its administration. CONCLUSIONS: AA can be of benefit to some patients requiring treatment with corticosteroids, but suffering from the side effect of elevated IOP