Photonic and Nanomechanical Modes in Acoustoplasmonic Toroidal Nanopropellers.

Non-conventional resonances, both acoustic and photonic, are found in metallic particles with a toroidal nanopropeller geometry, which is generated by sweeping a three-lobed 2D shape along a spiral with twisting angle α. For both optical and acoustic cases, the spectral location of resonances experiences a red-shift as a function of α. We demonstrate that the optical case can be understood as a natural evolution of resonances as the spiral length of the toroidal nanopropeller increases with α, implying a huge helicity-dependent absorption cross-section. In the case of acoustic response, two red-shifting breathing modes are identified. Additionally, even a small α allows the appearance of new low-frequency resonances, whose spectral dispersion depends on a competition between the length of the generative spiral and the pitch of the toroidal nanopropeller.

Opponent control of behavior by dorsomedial striatal pathways depends on task demands and internal state.

A classic view of the striatum holds that activity in direct and indirect pathways oppositely modulates motor output. Whether this involves direct control of movement, or reflects a cognitive process underlying movement, remains unresolved. Here we find that strong, opponent control of behavior by the two pathways of the dorsomedial striatum depends on the cognitive requirements of a task. Furthermore, a latent state model (a hidden Markov model with generalized linear model observations) reveals that-even within a single task-the contribution of the two pathways to behavior is state dependent. Specifically, the two pathways have large contributions in one of two states associated with a strategy of evidence accumulation, compared to a state associated with a strategy of repeating previous choices. Thus, both the demands imposed by a task, as well as the internal state of mice when performing a task, determine whether dorsomedial striatum pathways provide strong and opponent control of behavior.

Hybridization of electronic states in quantum dots through photon emission.

The self-assembly of semiconductor quantum dots has opened up new opportunities in photonics. Quantum dots are usually described as 'artificial atoms', because electron and hole confinement gives rise to discrete energy levels. This picture can be justified from the shell structure observed as a quantum dot is filled either with excitons (bound electron-hole pairs) or with electrons. The discrete energy levels have been most spectacularly exploited in single photon sources that use a single quantum dot as emitter. At low temperatures, the artificial atom picture is strengthened by the long coherence times of excitons in quantum dots, motivating the application of quantum dots in quantum optics and quantum information processing. In this context, excitons in quantum dots have already been manipulated coherently. We show here that quantum dots can also possess electronic states that go far beyond the artificial atom model. These states are a coherent hybridization of localized quantum dot states and extended continuum states: they have no analogue in atomic physics. The states are generated by the emission of a photon from a quantum dot. We show how a new version of the Anderson model that describes interactions between localized and extended states can account for the observed hybridization.

Divergent projections of the prelimbic cortex bidirectionally regulate active avoidance.

The prefrontal cortex (PFC) integrates incoming information to guide our actions. When motivation for food-seeking competes with avoidance of danger, the PFC likely plays a role in selecting the optimal choice. In platform-mediated active avoidance, rats avoid a tone-signaled footshock by stepping onto a nearby platform, delaying access to sucrose pellets. This avoidance requires prelimbic (PL) PFC, basolateral amygdala (BLA), and ventral striatum (VS). We previously showed that inhibitory tone responses of PL neurons correlate with avoidability of shock (Diehl et al., 2018). Here, we optogenetically modulated PL terminals in VS and BLA to identify PL outputs regulating avoidance. Photoactivating PL-VS projections reduced avoidance, whereas photoactivating PL-BLA projections increased avoidance. Moreover, photosilencing PL-BLA or BLA-VS projections reduced avoidance, suggesting that VS receives opposing inputs from PL and BLA. Bidirectional modulation of avoidance by PL projections to VS and BLA enables the animal to make appropriate decisions when faced with competing drives.

Early readmission of low-risk patients after coronary surgery.

BACKGROUND: Early readmission after coronary artery bypass grafting (CABG) is an expensive adverse outcome. Although the perioperative experience of high-risk CABG patients has been studied extensively, little attention has been paid to low-risk CABG patients. The primary goal of this study was to identify the preoperative characteristics and to define risk predictors of readmission and preventive factors for readmission in low-risk isolated-CABG patients. METHODS: We identified 2157 patients who underwent CABG between January 2000 and December 2005 at Washington Hospital Center, Washington, DC, and defined as low risk patients who had a Parsonnet bedside risk score lower than the 25th percentile. Patients who were rehospitalized within 30 days after surgery were compared with those who were not rehospitalized during this period. RESULTS: The overall readmission rate for this study cohort was 6.3%. Compared with non-readmitted patients, early-readmitted patients were more likely to have diabetes mellitus (27.94% versus 20.88%, P = .05) and less likely to have hypertension (42.65% versus 51.36%, P = .05). Blood product transfusion (P < .01), postoperative length of intensive care unit stay (P = .01), and length of hospital stay (P = .05) were all significantly increased in the readmitted patients. The use of beta-blockers (P = .03) and angiotensin-converting enzyme inhibitors (P = .04) was significantly lower at discharge in this group of patients; however, multivariate regression analysis demonstrated diabetes (odds ratio, 1.59; 95% confidence interval, 1.08-2.42) to be the only independent predictor of early readmission. CONCLUSIONS: For low-risk CABG patients, diabetes mellitus is the risk predictor of early readmission. Early discharge was not associated with early readmission.

Isolated self-assembled InAs/InP(001) quantum wires obtained by controlling the growth front evolution.

In this work we explore the first stages of quantum wire (QWR) formation studying the evolution of the growth front for InAs coverages below the critical thickness, theta(c), determined by reflection high energy electron diffraction (RHEED). Our results obtained by in situ measurement of the accumulated stress evolution during InAs growth on InP(001) show that the relaxation process starts at a certain InAs coverage theta(R)theta(R) this ensemble of isolated nanostructures progressively evolves towards QWRs that cover the whole surface for theta = theta(c). These results allow for a better understanding of the self-assembling process of QWRs and enable the study of the individual properties of InAs/InP self-assembled single quantum wires.

Operative mortality after conventional versus coronary revascularization without cardiopulmonary bypass.

OBJECTIVE: Off-pump coronary artery bypass (CABG) is a safe revascularization option with comparable or superior results to the conventional on-pump CABG. However, comparative analysis of the type of surgical approach on the mortality rate is largely unknown. This study sought to investigate whether CABG without cardiopulmonary bypass (off-pump CABG) is associated with lower operative mortality than the conventional on-cardiopulmonary bypass (on-pump) approach. METHODS: From October 1998 to June 2001, off-pump CABG was performed on 2477 patients and on-pump CABG was performed on 3077 patients. The patients undergoing off-pump CABG were randomly matched to on-pump patients via propensity score. Seventy-four percent of the off-pump CABG patients were matched with on-pump patients via propensity scores. A logistic regression model was used to test the difference in the postoperative mortality rate between off-pump CABG and on-pump CABG, controlling the correlation between matched sets. A multiple logistic regression model predicting the risk of mortality adjusted by risk factors of mortality and operation type was computed. RESULTS: Results from the general estimating equation showed that patients who had on-pump CABG were 1.6 (95% confidence intervals (CI)=1.2-2.0, P<0.01) times more likely to die during the first 30 days after surgery than patients who had off-pump CABG. Independent predictors of 30-day mortality identified from the multiple logistic model included on-pump CABG (versus off-pump CABG), advanced age, female gender, carotid artery disease, chronic renal failure, depressed ejection fraction, reoperative CABG, preoperative intraaortic balloon counterpulsation, and recent myocardial infarction. CONCLUSION: Excellent clinical results and a lower operative mortality rate can be achieved with the off-pump CABG technique compared with the conventional on-pump approach.

Clinical outcomes of coronary revascularization without cardiopulmonary bypass.

OBJECTIVE: Coronary artery bypass without cardiopulmonary bypass (OPCAB) eliminates the complications related to cardiopulmonary bypass. However, the long-term outcomes of this procedure are largely unknown. METHODS: We sought to investigate the rates of late mortality, stroke, acute myocardial infarction, and target vessel reintervention after OPCAB in a consecutive series of 857 patients who underwent OPCAB between May 1987 and March 1999. RESULTS: Long-term follow-up was obtained for 86% of eligible patients. Actuarial and event-free survival was 89% and 76%, respectively, for a median follow-up period of 2.2 years (range, 0-13.3 years). Risk factors for late mortality were identified with Cox regression analysis. In the multivariate analysis, patient age >75 years (odds ratio, 1.1; 95% confidence interval, 1.0-1.1; P =.01) and an ejection fraction <35% (odds ratio, 2.7; 95% confidence interval, 1.2-6.2; P =.02) emerged as independent predictors of late mortality. CONCLUSION: OPCAB is associated with a low mortality and clinical event rate. Advanced age and depressed ejection fraction may increase mortality after OPCAB.

Comparison of frequency of atrial fibrillation after coronary artery bypass grafting in African Americans versus European Americans.

In the general population, African Americans experience atrial fibrillation (AF) less frequently than European Americans. This difference could also exist in the incidence of this arrhythmia after cardiac surgery, but this possibility has been insufficiently examined. To test the association of such an ethnic difference, we compared the incidence of postoperative AF in a consecutive series of 2,312 African Americans and 6,054 European Americans who underwent isolated coronary artery bypass grafting from July 2000 to June 2007. Raw differences between the cohorts in the incidence of new AF were adjusted to take into account the baseline differences. Postoperatively, new-onset AF developed in 504 (22%) of 2,312 African-American patients and in 1,838 (30%) of 6,054 European-American patients (p <0.01). After adjustment with logistic regression analysis for numerous baseline differences, African Americans remained less likely to develop AF (odds ratio 0.63, 95% confidence interval 0.55 to 0.72; p <0.001). Risk was also adjusted using propensity matching. In that analysis, 457 (22%) of 2,059 African-American patients had postoperative AF, as did 597 (29%) of 2,059 matched European-American patients (p <0.01). In conclusion, AF was significantly less common among African-American patients than among European-American patients after coronary artery bypass grafting.

Is cardiac surgery safe in extremely obese patients (body mass index 50 or greater)?

BACKGROUND: We investigated the impact of extreme obesity (body mass index [kg/m(2)] 50 or greater) on short-term clinical outcomes and report 1-year mortality. METHODS: Fifty-seven patients were found to have a body mass index of 50 or greater among 14,449 patients who underwent cardiac surgery between July 2000 and June 2007. Multivariable logistic regression analyses were used to assess the independent influence of extreme obesity on the major outcomes. RESULTS: Of the 57 patients, the mean age was 58 +/- 11 years, mean body mass index was 55.1, and 63% of the patients were women. Forty patients underwent elective surgery. Forty-one patients had isolated coronary artery bypass graft surgery. The overall operative mortality was 9%; the mortality was 5% in isolated coronary artery bypass graft surgery and 5% in elective surgery. Fifteen patients had nonelective isolated coronary artery bypass graft surgery, and 2 patients had emergent active endocarditis surgery. Off-pump coronary artery bypass graft surgery was performed on 23 patients (23 of 41, 54%). After adjusting for known preoperative and operative risk factors through a multivariate logistic model, extreme obesity did not emerge as a significant risk factor for operative mortality (odds ratio, 1.75; p = 0.47) and other adverse outcomes (p > 0.05) after elective surgery; however, extreme obesity was marginally associated with increased mortality (odds ratio, 2.69; p = 0.05) and was a risk predictor for longer intensive care unit stays (odds ratio, 2.43; p = 0.01) in overall surgery. The 1-year survival rate was 82.5%. CONCLUSIONS: Extreme obesity is not a contraindication to elective cardiac surgery. Studies stratifying the risk factors of mortality for nonelective surgery in extremely obese patients may be warranted.

Current practice and outcomes of off-pump multivessel coronary artery bypass.

Outcomes of off-pump multivessel coronary artery bypass were compared with those of the on-pump procedure. From July 2001 to June 2006, 3,637 patients with multivessel coronary disease underwent off-pump coronary artery bypass, and 3,586 patients had on-pump coronary artery bypass in our center. The rates of operative mortality, permanent stroke, renal failure and perioperative myocardial infarction were significantly lower in the off-pump group, and these patients required fewer blood transfusions, shorter durations of ventilatory support, and shorter hospital stays. However, the patients who underwent on-pump coronary artery bypass were considered more high-risk and tended to have more complex procedures.

Off-pump coronary artery bypass grafting improves in-hospital mortality in patients with dialysis-dependent renal failure.

OBJECTIVE: Patients with chronic dialysis-dependent end-stage renal disease are increasingly referred for coronary artery bypass grafting (CABG) and their early outcome is less favorable. Off-pump CABG (OPCAB) has achieved encouraging results in high-risk patients. Therefore, we designed this retrospective study to test the hypothesis that OPCAB reduced surgical risks in dialysis patients. METHODS: From January 2000 to December 2005, 294 dialysis-dependent patients received isolated CABG at the Washington Hospital Center. Among them, 168 underwent OPCAB (off-pump group), and 126, CABG with cardiopulmonary bypass (CPB) (on-pump group). The in-hospital outcomes were analyzed. RESULTS: The two groups were comparable in terms of preoperative characteristics. The Parsonnet's Bedside Score of the off-pump group was similar to that of the on-pump group (32.0 vs. 32.0, P=.57). The in-hospital mortality of the off-pump group was significantly lower than that of the on-pump group (5.4% vs. 11.9%, P=.04). Although the percentage of patients who received transfusions was similar, the on-pump group received more total transfusions. Logistic regression analysis revealed that use of CPB independently predicted in-hospital mortality [odds ratio (OR), 5.0; 95% confidence interval, 1.78-13.85; P<.01] and perioperative myocardial infarction (MI; OR, 5.1; 95% confidence interval, 1.18-22.40; P=.03). No significant difference in long-term survival at 4 years was absorbed between the two groups of hospital survivors. CONCLUSIONS: Our data suggest that OPCAB is a safe alternative to on-pump CABG in dialysis patients. Avoiding CPB resulted in less perioperative blood utilization, MI, and hospital mortality.

Cardiac surgery in renal transplant recipients: experience from Washington Hospital Center.

BACKGROUND: The number of renal transplant survivors requiring surgical treatment for cardiovascular diseases is increasing. A retrospective study was conducted to determine the outcomes of renal transplant recipients undergoing cardiac surgery. METHODS: Fifty-seven renal transplant recipients whose cardiac surgery was performed between 1987 and 2004, and whose allograft was functioning at the time of cardiac surgery, were identified. We analyzed postoperative mortality and morbidity as well as late mortality. RESULTS: Among 57 patients, 70.2% had hypertension, 54.4% diabetes, and 28.1% poor left ventricular function (ejection fraction < 0.35). Preoperative renal insufficiency (serum creatinine level > or = 3 mg/dL) was noted in 12.3% of the patients. Coronary artery disease was the dominant indication for the surgery. The median interval from renal transplant to cardiac surgery was 60 months. In-hospital mortality was 5.3%. All deaths were cardiac-related. Infectious complications occurred in 17.5% of the patients. Acute allograft failure requiring hemodialysis occurred in 28.6% of the patients with preoperative renal insufficiency, more frequent than those without preoperative renal insufficiency. Multivariable analysis identified preoperative renal insufficiency, mitral valve disease, and left ventricular dysfunction as independent predictors of in-hospital major adverse events (including death, infection, and renal failure). The 3-year survival was 71% after a median follow-up of 34 months. CONCLUSIONS: Infection control and renal protection should be stressed to ensure the safety of cardiac surgery in this patient group, while preoperative renal insufficiency, mitral valve disease, and left ventricular dysfunction are associated with early adverse outcomes. In the renal transplant recipients undergoing an isolated CABG, avoidance of cardiopulmonary bypass and use of arterial grafts might lead to better outcomes.