Idaho National Lab Impedance Measurement Box High Voltage Coupling Circuit

Our project goal is to build a 300V [1] coupling circuit for the Idaho National Lab’s (INL) Impedance Measurement Box (IMB). The IMB is a device that determines the frequency spectrum of the internal impedance of a battery by measuring its impedance to various frequencies. The procedure involves the box outputting a sum of sines (SOS) signal into a battery, capturing its voltage response, and processing the voltage time record into an impedance spectrum. This allows the box to determine the internal impedance of the battery, which can be used to predict the battery’s life and other characteristics. [2] The IMB is currently built to measure batteries of up to 50V. Our goal is to design and construct a circuit that will allow the box to measure batteries of up to 300V. This will be done through the use of a coupling circuit and a state machine. The coupling circuit will operate by using a high voltage capacitor and resistors to protect the IMB and allow it to measure the battery without the source voltage ever exceeding 30V, which is the max the future IMB is designed to safely handl

Transient advanced mental impairment: An underappreciated morbidity after aortic surgery

AbstractObjectives: To determine the incidence, risk factors, and associated morbidity of transient advanced mental impairment (TAMI) after aortic surgery. Methods: We retrospectively studied the charts of 188 consecutive patients undergoing elective aortic reconstruction during a recent 6-year period at a university hospital. All patients were lucid on admission and nonintubated at the time of evaluation at least 2 days after operation. TAMI was defined as disorientation or confusion on 2 or more postoperative days. Preoperative, intraoperative, and postoperative clinical variables were examined statistically for associations with TAMI. Results: Fifty-three patients (28%) had development of TAMI 3.9 ± 2.8 days after operation. Stepwise logistic regression analysis selected the following independent predictors for TAMI: age >65 years (odds ratio [OR], 7.9; 95% confidence interval [CI], 2.7 to 23.7), American Society of Anesthesiology physical status classification >3 (OR, 2.8; 95% CI, 1.3 to 5.9), diabetes mellitus (OR, 3.4; 95% CI, 1.2 to 9.8), old myocardial infarction (OR, 2.4; 95% CI, 1.1 to 5.3), and hypertension (OR, 2.3; 95% CI, 1.0 to 5.3). Alcohol consumption was not significantly associated with TAMI. In the postoperative period, patients with TAMI were more likely to have hypoxia (P <.001), a need for reintubation (P <.001), pneumonia (P <.001), congestive heart failure (P =.003), and kidney failure (P =.05). In addition, patients with TAMI had a longer duration of endotracheal intubation (3.7 ± 7.8 vs 0.6 ± 1.2 days, P <.001), stay in the intensive care unit (8.9 ± 9 vs 3.9 ± 2 days, P <.001), and postoperative hospital stay (14.8 ± 11 vs 9.2 ± 5 days, P <.001) than patients without TAMI. Twenty (38%) patients with TAMI were discharged to intermediate-care facilities, compared with 11 (8%) patients without TAMI (P <.001). Postoperative variables conferring the largest relative risks for development of TAMI included oxygen saturation less than 92% (5.4), the need for reintubation (3.3), congestive heart failure (3.3), and pneumonia (3.2). TAMI, conversely, conferred the largest relative risks for development of postoperative congestive heart failure (15.3), the need for reintubation (9.3), pneumonia (7.1), and the need for ICU readmission (3.8). Conclusions: These data show that TAMI is prevalent among patients undergoing aortic reconstruction and is associated with dramatically increased morbidity and postoperative hospitalization rates. (J Vasc Surg 2002;35:376-81.

Do preoperative finger pressures predict early arterial steal in hemodialysis access patients? A prospective analysis

AbstractBackground: Hand ischemia resulting from arterial steal is a serious complication in patients undergoing hemodialysis access, but specific risk factors for steal remain in dispute. The purpose of this study was to determine whether plethysmographically derived finger pressures (FPs) or digital-brachial indices (DBIs) are predictive of symptomatic arterial steal. Methods: We prospectively studied 72 patients (37 men, 35 women; mean age, 57 ± 10 years) who were undergoing brachial artery-based hemodialysis access. All patients had complete pre- and postoperative hand examinations and FP determinations. Surgeons were blinded to preoperative FP results. Results: Prosthetic graft was used in 60 patients (6-mm polytetrafluoroethylene [PTFE] in 50, tapered PTFE in 10), and brachial-based arteriovenous fistulas were created in 12. Fourteen (19%) patients developed arterial steal symptoms. The mean preoperative FP was significantly lower in steal patients than in those without steal (131 ± 27 vs 151 ± 31 mm Hg, P < .03). Nine (64%) of the patients with steal had DBIs <1.0, compared to 18 (31%) of the patients without steal (P = .02). However, there was no absolute FP or DBI threshold below which steal was inevitable. The occurrence of steal was attributed to proximal arterial stenoses in seven, to distal arterial disease in five, and was unknown in two. When comparing the 14 patients who developed steal to the 58 who did not, we noted that a higher proportion of steal patients had coronary artery disease (57% vs 17%, P = .005). Steal was more likely to develop in patients with arteriovenous fistulas than in patients with prosthetic grafts (43% vs 14%, P = .009). There were no significant differences in demographic factors, atherosclerotic risks (diabetes, smoking, hypertension, dyslipidemia), prevalence of peripheral vascular disease, cerebrovascular disease, shunt location, tapered vs straight graft, or number of prior grafts placed. Conclusions: These data indicate that preoperative FPs are lower in patients who develop steal syndrome after hemodialysis access. Patients with preoperative DBIs <1.0 are more likely to develop steal, but there is no DBI threshold below which steal is inevitable. Steal is more likely in patients undergoing brachial-based arteriovenous fistulas than in those receiving prosthetic grafts. (J Vasc Surg 2002;36:351-6.

Polycomb recruitment attenuates retinoic acid-induced transcription of the bivalent NR2F1 gene

Polycomb proteins play key roles in mediating epigenetic modifications that occur during cell differentiation. The Polycomb repressive complex 2 (PRC2) mediates the tri-methylation of histone H3 lysine 27 (H3K27me3). In this study, we identify a distinguishing feature of two classes of PRC2 target genes, represented by the Nr2F1 (Coup-TF1) and the Hoxa5 gene, respectively. Both genes are transcriptionally activated by all-trans retinoic acid (RA) and display increased levels of the permissive H3K9/K14ac and tri-methylated histone H3 lysine 4 epigenetic marks in response to RA. However, while in response to RA the PRC2 and H3K27me3 marks are greatly decreased at the Hoxa5 promoter, these marks are initially increased at the Nr2F1 promoter. Functional depletion of the essential PRC2 protein Suz12 by short hairpin RNA (shRNA) technology enhanced the RA-associated transcription of Nr2F1, Nr2F2, Meis1, Sox9 and BMP2, but had no effect on the Hoxa5, Hoxa1, Cyp26a1, Cyp26b1 and RARβ2 transcript levels in wild-type embryonic stem cells. We propose that PRC2 recruitment attenuates the RA-associated transcriptional activation of a subset of genes. Such a mechanism would permit the fine-tuning of transcriptional networks during differentiation