Room-temperature strong coupling between CdSe nanoplatelets and a metal-DBR Fabry-Pérot cavity.

The generation of exciton-polaritons through strong light-matter interactions represents an emerging platform for exploring quantum phenomena. A significant challenge in colloidal nanocrystal-based polaritonic systems is the ability to operate at room temperature with high fidelity. Here, we demonstrate the generation of room-temperature exciton-polaritons through the coupling of CdSe nanoplatelets (NPLs) with a Fabry-Pérot optical cavity, leading to a Rabi splitting of 74.6 meV. Quantum-classical calculations accurately predict the complex dynamics between the many dark state excitons and the optically allowed polariton states, including the experimentally observed lower polariton photoluminescence emission, and the concentration of photoluminescence intensities at higher in-plane momenta as the cavity becomes more negatively detuned. The Rabi splitting measured at 5 K is similar to that at 300 K, validating the feasibility of the temperature-independent operation of this polaritonic system. Overall, these results show that CdSe NPLs are an excellent material to facilitate the development of room-temperature quantum technologies.

Efficient Hole Transfer from CdSe Quantum Dots Enabled by Oxygen-Deficient Polyoxovanadate-Alkoxide Clusters.

A limitation of the implementation of cadmium chalcogenide quantum dots (QDs) in charge transfer systems is the efficient removal of photogenerated holes. Rapid hole transfer has typically required the ex situ functionalization of hole acceptors with groups that can coordinate to the surface of the QD. In addition to being synthetically limiting, this strategy also necessitates a competitive binding equilibrium between the hole acceptor and native, solubilizing ligands on the nanocrystal. Here we show that the incorporation of oxygen vacancies into polyoxovanadate-alkoxide clusters improves hole transfer kinetics by promoting surface interactions between the metal oxide assembly and the QD. Investigating the reactivity of oxygen-deficient clusters with phosphonate-capped QDs reveals reversible complexation of the POV-alkoxide with a phosphonate ligand at the nanocrystal surface. These findings reveal a new method of facilitating QD-hole acceptor association that bypasses the restrictions of exchange interactions.

Localized Charge on Surfactant-Wrapped Single-Walled Carbon Nanotubes.

As-synthesized, semiconducting single-walled carbon nanotubes (SWCNTs) are nominally charge neutral. However, ionic surfactants that are commonly used to disperse SWCNTs in solution can lead to significantly charged aggregates adsorbed to the nanotube. Here, electrostatic force microscopy (EFM) was used to characterize the static-charge interactions between individual SWCNTs and the local environment. We report nonuniform spatial charge distributions with highly varying magnitudes ranging between ±15 e associated with surfactant coverage on long SWCNTs (>1.5 µm). EFM images acquired after resonant photoexcitation demonstrate charge carrier localization due to electrostatic interactions with charged surfactant aggregates. Charge densities as measured by EFM are used to estimate the depth of this electrostatically induced potential well, calculated to be on the order of hundreds of millielectronvolts, suggesting that surfactant charges heterogeneously covering SWCNTs provide traps for excitons potentially leading to their localization.

Optimization of ultraviolet Raman spectroscopy for trace explosive checkpoint screening.

Raman spectroscopy has long been considered a gold standard for optically based chemical identification, but has not been adopted in non-laboratory operational settings due to limited sensitivity and slow acquisition times. Ultraviolet (UV) Raman spectroscopy has the potential to address these challenges through the reduction of fluorescence from background materials and increased Raman scattering due to the shorter wavelength (relative to visible or near-infrared excitation) and resonant enhancement effects. However, the benefits of UV Raman must be evaluated against specific operational situations: the actual realized fluorescence reduction and Raman enhancement depend on the specific target materials, target morphology, and operational constraints. In this paper, the wavelength trade-space in UV Raman spectroscopy is evaluated for one specific application: checkpoint screening for trace explosive residues. The optimal UV wavelength is evaluated at 244, 266, and 355 nm for realistic trace explosive and explosive-related compound (ERC) residues on common checkpoint materials: we perform semi-empirical analysis that includes the UV penetration depth of common explosive and ERCs, realistic explosive and ERC residue particle sizes, and the fluorescence signal of common checkpoint materials. We find that while generally lower UV wavelength provides superior performance, the benefits may be significantly reduced depending on the specific explosive and substrate. Further, logistical requirements (size, weight, power, and cost) likely limit the adoption of optimal wavelengths. Graphical abstract.

Percutaneous renal artery intervention versus medical therapy in patients with renal artery stenosis: a meta-analysis.

AIMS: Patients with renal artery stenosis are treated with percutaneous intervention, but randomised studies are inconclusive. We aimed to compare renal percutaneous revascularisation versus medical therapy. METHODS AND RESULTS: A systematic search for randomised controlled studies yielded three studies comparing renal angioplasty and two studies comparing renal angioplasty with stenting versus medical therapy, respectively. Six sets of data were extracted focusing on systolic and diastolic blood pressure as well as serum creatinine at follow-up. The five trials included 1,030 patients with renal artery stenosis. There was a trend toward, but no significant improvement in, systolic blood pressure (weighted mean difference [WMD] -2.76 mmHg, 95% confidence interval (CI) -5.71 to 0.18; p=0.07), diastolic blood pressure, (WMD -1.18 mmHg, 95% CI -2.69 to 0.32; p=0.12), or serum creatinine (WMD -7.26 mmol/L, 95% CI -14.99 to 0.47; p=0.07) in the patients who underwent percutaneous intervention compared to the medical therapy group. All but one trial showed at least a moderate overall bias risk. CONCLUSIONS: We did not find a significant improvement in blood pressure or renal function in patients with renal artery stenosis treated with renal artery revascularisation compared to medical therapy alone. However, trial quality was a limitation.

The effect of device advisories on implantable cardioverter-defibrillator therapy.

Implantable cardioverter-defibrillators have been shown to improve survival by terminating life-threatening ventricular tachyarrhythmias. As the devices have become more complex, there has been an increase in the incidence of device and lead malfunction. The device manufacturers issue advisories and recalls to alert physicians of the potential for malfunction. When patients are faced with a recalled device or lead, the initial question is whether or not to replace it. A rational approach to evaluating these patients and the associated advisory can help gauge the competing risks of elective device removal or extraction versus keeping the device in place. It is important to keep in mind that the risks of replacing devices or extracting leads are not insignificant and may outweigh the risks of death from malfunction. Despite the increasing number of advisories and attention to device and lead failure, the overall reliability and efficacy of these devices for appropriate patients remains high. In general, patients should be counseled prior to implant of the potential for device and lead malfunction, and careful consideration must be employed when decisions are made to replace generators or extract leads.

Should recent defibrillator and lead advisories affect decisions to refer patients for implantable cardioverter-defibrillator therapy?

PURPOSE OF REVIEW: Implantable cardioverter-defibrillators (ICDs) have been shown to improve survival by terminating life-threatening ventricular arrhythmias. As ICDs have become more complex, there has been an increase in the incidence of device and lead malfunctions. Advisories and recalls are issued by device manufacturers to alert physicians to potential malfunction, but the management is typically left to the physician. We reviewed recent data on ICD and lead advisories, in addition to studies evaluating associated consequences, to determine whether advisories affect the benefit of device therapy and how best to manage device advisories. RECENT FINDINGS: Despite the increasing number of advisories and attention to device and lead failure, the overall reliability and efficacy of ICDs for appropriate patients remain high. Careful consideration must be employed when decisions are made to replace generators or extract leads, as these additional procedures can lead to more significant adverse complications compared with the advisory and potential for malfunction. SUMMARY: Patients continue to benefit from ICD implantation despite recent advisories for potential device and lead malfunction. The decision for ICD implantation should still be based on the patient's risk of experiencing a life-threatening arrhythmia. Patients should be counseled prior to implant of the potential for device and lead malfunction, and careful consideration must be employed in the setting of an advisory prior to replacing an affected device or lead.

Atherosclerotic renal artery stenosis: current therapy and future developments.

Atherosclerotic renal artery stenosis affects between 2 and 4 million people in the United States alone and likely has a higher prevalence than previously thought. Renal artery stenosis has been increasingly recognized in recent years, especially in patients with cardiovascular disease. It has been associated with hypertension, renal dysfunction, and sudden onset of pulmonary edema. Patients with symptomatic and hemodynamically significant renal artery stenosis are candidates for revascularization. Revascularization is most often accomplished by renal artery stenting, which has high success rates in terms of patency and low complication rates. An important element in managing patients with renal artery stenosis is selecting those patients who are most likely going to benefit from revascularization. This review article focuses on the clinical diagnosis, current treatment options, and future directions regarding treatment of patients with renal artery stenosis.

Clinical judgment versus decision analysis for managing device advisories.

INTRODUCTION: Implantable cardioverter-defibrillator (ICD) and pacemaker (PM) advisories may have a significant impact on patient management. Surveys of clinical practice have shown a great deal of variability in patient management after a device advisory. We compared our management of consecutive patients in a single large university practice with device advisories to the "best" patient management strategy predicted by a decision analysis model. METHODS: We performed a retrospective review of all patients who had implanted devices affected by an advisory at our medical center between March 2005 and May 2006 and compared our actual patient management strategy with that subsequently predicted by a decision analysis model. RESULTS: Over 14 months, 11 advisories from three different manufacturers affected 436 patients. Twelve patients (2.8%) were deceased and 39 patients (8.9%) were followed at outside facilities. Management of the 385 remaining patients varied based on type of malfunction or potential malfunction, manufacturer recommendations, device dependency, and patient or physician preferences. Management consisted of the following: 57 device replacements (15.2%), 44 devices reprogrammed or magnets issued (11.7%), and 268 patients underwent more frequent follow-up (71.3%). No major complications, related to device malfunction or device replacement, occurred among any patient affected with a device advisory. Concordance between the decision analysis model and our management strategy occurred in 57.1% of cases and 25 devices were replaced when it was not the preferred treatment strategy predicted by the decision model (43.9%, 37.3% when excluding devices replaced based on patient preference). The decision analysis favored replacement for all patients with PM dependency, but only for four patients with ICDs for secondary prevention. No devices were left implanted that the decision analysis model predicted should have been replaced. CONCLUSIONS: We found that despite a fairly conservative device replacement strategy for advisories, we still replaced more devices when it was not the preferred device management strategy predicted by a decision analysis model. This study demonstrates that even when risks and benefits are being considered by experienced clinicians, a formal decision analysis can help to develop a systematic evidence based approach and potentially avoid unnecessary procedures.

Benefit of primary prevention implantable cardioverter-defibrillators in the setting of chronic kidney disease: a decision model analysis.

INTRODUCTION: Primary prevention ICD trials have excluded patients with CKD. Comorbidities and lower life expectancy in patients with CKD make the benefit of primary prevention ICD implantation uncertain. METHODS: A decision analysis model was devised to evaluate the risks and benefits of implantable cardioverter-defibrillators (ICD) implantation in patients with chronic kidney disease (CKD) who meet current criteria for a primary prevention ICD. Published data capturing event rates, infection risks, and overall survival in CKD patients with and without ICDs were utilized. Variables included patient's age, GFR and stage of CKD, probability of sudden cardiac death (SCD), and device implantation mortality. RESULTS: The benefit of an ICD for primary prevention of SCD in patients with CKD depends primarily on the patient's age and stage of kidney disease. With stages 1 and 2 CKD, ICD implantation reduces mortality. However, in patients with more advanced stages of CKD, the benefit is less significant and age-dependent. This is attributed to patients with advanced CKD having a higher procedural risk and decreased life expectancy. With average procedural mortality, ICD implantation is favored at ages <80 for stage 3, ages <75 for stage 4, and ages <65 for stage 5. As procedural mortality rates increase, age thresholds for ICD implantation decrease. CONCLUSIONS: Our model shows that benefit from primary prevention ICD implantation is determined by the patient's age and stage of kidney disease. While there is limited impact with lower stages of CKD, careful consideration of ICD implantation is suggested for older patients with more advanced stages of kidney disease.

Gender disparity in the use of cardiac resynchronization therapy in the United States.

BACKGROUND: Although several studies have shown the effectiveness of cardiac resynchronization therapy (CRT) for advanced congestive heart failure (CHF), gender differences in utilization of CRT are not known. METHODS: We used the Healthcare Cost and Utilization Project (HCUP) to study national rates for admissions due to CHF along with procedures for initial CRT implantation, including both CRT-defibrillator (CRT-D) and CRT-pacemakers (CRT-P) during the years of 2002-2004. Chi-square tests were used for comparison between number of women and men. A P < 0.05 was considered significant. RESULT: Women had consistently higher rates of admission for CHF during each year (574,037 (54%) vs 482,005 (46%), 2002; 601,181 (54%) vs 517,202 (46%), 2003; and 580,913 (53%) vs 521,280 (47%), 2004). The number of initial CRT device implantations (both CRT-D and CRT-P) was significantly lower during each year for women compared to men (659 (25%) vs 1,931 (75%), 2002; 6,928 (26%) vs 19,646 (74%), 2003; and 11,286 (27%) vs 42,196 (73%), 2004; P < 0.01 for all). Both CRT-P and CRT-D were used less frequently in women compared to men; however, this difference was consistently less prominent during each year with CRT-P compared to CRT-D (301 (41%) CRT-P vs 358 (19%) CRT-D, 2002; 659 (39%) CRT-P vs 2,530 (28%) CRT-D, 2003; and 2,891 (39%) CRT-P vs 8,395 (24%) CRT-D, 2004; P < 0.05). CONCLUSION: Our data clearly demonstrate a significant gender disparity in utilization of CRT devices. Further studies are needed to find possible reasons behind this disparity.

Focus on management of pacemaker and ICD advisories, recalls, and alerts.

Because the number of implantable cardiac devices has dramatically increased, device alerts and advisories have become a part of routine clinical practice. When a physician is faced with the management of a patient with an implanted device that has been the subject of a recall or advisory, the major concern facing the clinician is how to manage the patient and whether the device needs to be replaced. A rational approach to evaluating patients with a device or lead that is the subject of a US Food and Drug Administration advisory requires evaluating the competing risks of elective device or lead replacement versus keeping the recalled device or lead in place. It is important to keep in mind that the risks of replacing devices are not insignificant and may outweigh the risks of death from device malfunction. Ultimately, this decision should be based on the estimated device (lead) malfunction rate, device (lead) dependency, and an individual center's procedural risk for complications from generator (lead) removal, and should also factor in patient preferences.

Management of recalled pacemakers and implantable cardioverter-defibrillators: a decision analysis model.

CONTEXT: Limited information exists to direct clinical management after an implantable device has been put under advisory. A better understanding of the risks and benefits of device replacement compared with continued clinical follow-up would be helpful to clinicians. OBJECTIVE: Using the tools of decision analysis, to determine the best management approach (immediate device replacement vs continued monitoring) in the setting of a device advisory. DESIGN: A decision model was constructed to evaluate the risks and benefits associated with immediate device replacement compared with continued monitoring. MAIN OUTCOME MEASURES: Variables considered included indications for device implantation, anticipated course following device failure, device failure rates from the advisory ranging from 0.0001% to 1.0% per year, and device replacement mortality rates ranging from 0.10% to 1.00% per procedure. Device replacement was preferred to continued follow-up when replacement led to greater patient survival. RESULTS: The decision to replace a recalled device depends primarily on the advisory's estimated device failure rate and the likely effects of device failure on mortality. Procedural mortality is an important secondary factor, while patient age and remaining generator life have the least influence on the decision. For pacemaker-dependent patients, advisory device failure rates exceeding 0.3% warrant device replacement in most situations. In patients with implantable cardioverter-defibrillators for primary or secondary prevention, a failure rate associated with an advisory of 3.0% is needed to favor replacement in most cases, decreasing to close to 1.0% as procedural mortality rates decrease to 0.1% or risk of fatal arrhythmias increase to near 20% per year. In cases of pacemaker implantation for non-life-threatening situations (eg, carotid sinus hypersensitivity), most device advisories do not warrant device replacement. CONCLUSIONS: The decision to replace a device under advisory is determined primarily by the incidence of device malfunction and the likely effects of device failure. This analysis provides a framework for managing recalled devices in the context of device, patient, and institutional characteristics.

Acute myocardial infarction and heart failure: role of apoptosis.

Apoptosis is a key pathologic feature in acute myocardial infarction and heart failure. Experimental animal studies have shown beneficial effects of inhibiting apoptosis. Understanding the mechanisms involved in the apoptotic cascade may be useful in better understanding of heart failure and its management. Not only in vivo detection of apoptosis may prove clinically useful in the diagnosis and risk stratification of patients with ischemic heart disease, but anti-apoptotic treatments (specific and non-specific) may be effective in the prevention and treatment of post-infarction remodelling and heart failure.