Outcomes Comparison of Robot-Assisted and Video-Assisted Thoracoscopic Cardiac Sympathetic Denervation.

OBJECTIVE: Cardiac sympathetic denervation (CSD) is a surgical antiadrenergic procedure that can reduce sustained ventricular tachyarrhythmia (VT). Video-assisted thoracoscopic surgery (VATS) is currently the standard approach used in CSD, and the practicality for robot-assisted thoracoscopic surgery (RATS) has yet to be investigated. METHODS: We conducted a single-center retrospective study of all adult patients (N = 67) who underwent CSD from 2015 to 2021. We compared short-term outcomes of those treated with RATS versus VATS thoracic sympathectomy. For patients with VT, we examined the effectiveness of a RATS approach in reducing implantable cardioverter defibrillator (ICD) shock burden. RESULTS: A total of 34 patients underwent RATS cardiac denervation, and 33 underwent VATS cardiac denervation. Those undergoing RATS denervation had a significantly shorter procedure duration with a median of 129 min (P = 0.008). Patients receiving the VATS approach were significantly more complicated by pneumothorax (P = 0.004) and overall complications (P = 0.01) when compared with the RATS approach. At 1 year after surgery, both groups had significant reductions in ICD shocks compared with before surgery, both decreasing from a median of 4 to 0 shocks (P < 0.001). In addition, at 1 year after surgery, the percentage of patients with persistent ICD shocks and the median of ICD shocks were similar between the groups. CONCLUSIONS: The RATS approach to cardiac denervation has similar 1-year follow-up outcomes in reducing recurrent VT as the VATS approach. However, patients undergoing RATS denervation experienced better perioperative outcomes. This shows promise for robotic CSD to be an effective and safe therapeutic option for patients with malignant arrhythmias.

Potential Role of Silencing Ribonucleic Acid for Esophageal Cancer Treatment.

INTRODUCTION: Esophageal cancer is an aggressive malignancy with high mortality. Optimal treatment of esophageal cancer remains an elusive goal. Ribonucleic acid (RNA) interference is a novel potential targeted approach to treat esophageal cancer. Targeting oncogenes that can alter critical cellular functions with silencing RNA molecules is a promising approach. The silencing of specific oncogenes in esophageal cancer cells in the experimental setting has been shown to decrease the expression of oncogenic proteins. This has resulted in cell apoptosis, reduction in cell proliferation, reduced invasion, migration, epithelial-mesenchymal transition, decrease in tumor angiogenesis and metastasis, and overcoming drug resistance. The Hedgehog (Hh) signaling pathway has been shown to be involved in esophageal adenocarcinoma formation in a reflux animal model. In addition to Hh, we will focus on other targets with clinical potential in the treatment of esophageal cancer. MATERIALS AND METHODS: We searched for articles published from 2005 to August 2020 that studied the siRNA effects on inhibiting esophageal cancer formation in experimental settings. We used combinations of the following terms for searching: "esophageal cancer," "RNA interference," "small interfering RNA," "siRNA," "silencing RNA," "Smoothened (Smo)," "Gli," "Bcl-2," "Bcl-XL," "Bcl-W,″ "Mcl-1," "Bfl-1," "STAT3,"and "Hypoxia inducible factor (HIF)". A total of 21 relevant articles were found. RESULTS AND CONCLUSIONS: Several proto-oncogenes/oncogenes including Hh pathway mediators, glioma-associated oncogene homolog 1 (Gli-1), Smoothened (Smo), and antiapoptotic Bcl-2 have potential as targets for silencing RNA in the treatment of esophageal cancer.

Effect of a combination of butorphanol and detomidine on endoscopic assessment of laryngeal function in Thoroughbred yearlings.

BACKGROUND: To the authors' knowledge, the effect of a combination of butorphanol tartrate and detomidine hydrochloride on the laryngeal function and symmetry of the arytenoid cartilages in young Thoroughbred horses has not been examined. Therefore, this study aimed to examine the effects of administration of butorphanol and detomidine on left-to-right rima glottidis ratio (L:R RGR), cross-sectional area of the rima glottidis (CSARG) and grade of laryngeal function of Thoroughbred yearlings examined endoscopically at rest. METHODS: Forty-six Thoroughbred yearlings underwent laryngeal video endoscopy, at rest, before and after sedation with butorphanol and detomidine. Three clinicians assigned grades of laryngeal function after reviewing the video recordings. The L:R RGR and CSARG were measured at the point of arytenoid cartilages' maximal abduction. Student's t-test was used to compare the L:R RGR and CSARG. Cohen's kappa (κ) was used to compare the intra- and interobserver agreements. Spearman's rank order was used to assess agreement between CSARG and grade of laryngeal function. RESULTS: Sedation had no effect on L:R RGR and CSARG. Mean intraobserver agreement of grade of laryngeal function of unsedated yearlings was 93.1%, and that of sedated yearlings was 92.9%. Mean interobserver agreement of grade of laryngeal function of unsedated yearlings was 92.8%, and that of sedated yearlings was 92.7%. Correlation between CSARG and laryngeal function grade was significant for both groups (p < 0.001). CONCLUSION: Sedating Thoroughbred yearlings with detomidine and butorphanol, before endoscopically examining the larynx, did not significantly affect the grade of laryngeal function.

There is an App for That: Mobile Technology Improves Complication Reporting and Resident Perception of Their Role in Patient Safety.

Morbidity and mortality (M&M) conferences are rooted within the culture of medicine. They serve a role in every training program and have been mandated by the Accreditation Council for Graduate Medical Education in surgical programs since 1983. Despite the patient safety improvements and educational benefits of these conferences, many adverse events are grossly under-reported. METHODS: We developed a web-based, Health Insurance Portability and Accountability Act-compliant, M&M reporting mobile application based on Research Electronic Data Capture. The list of possible complications was based on the American Board of Orthopaedic Surgery complications list for part II. The interface is accessible through all mobile platforms. All residents were encouraged to use the application for real-time reporting of complications. Using an unpaired T-test, we compared the reporting before and after the implementation of the mobile application. Residents were surveyed using the Agency for Healthcare Research and Quality Patient Safety Culture Survey before and after implementation to evaluate resident perception of the department's culture of safety. RESULTS: The application was launched in August 2017. All reported events were tallied from August 2016 through July 2019. Before the implementation of the application, there were 54 adverse events reported, with a mean of 4.0 per month. In the Post-App cohort, a total of 176 adverse events were reported in year 1, with a mean of 14.76 per month, and 236 adverse events were reported in year 2, with a mean of 19.66 per month. Residents were significantly more likely to feel that their input on patient safety was valued by attendings after the implementation of the app (p = 0.0243). CONCLUSIONS: An anonymous mobile reporting method for M&M significantly increased the reporting of both major and minor complications and improved resident perception of their role in patient safety efforts. This suggests that traditional methods of M&M reporting may grossly underestimate the complication rates which can negatively affect patient safety and quality improvement efforts and that reducing barriers to the reporting of complication may improve resident engagement in patient safety.

Fascia Iliaca Regional Anesthesia in Hip Fracture Patients Revisited: Which Fractures and Surgical Procedures Benefit Most?

OBJECTIVES: Perioperative fascia iliaca regional anesthesia (FIRA) decreases pain in hip fracture patients. The purpose of this study is to determine which hip fracture types and surgical procedures benefit most. DESIGN: Prospective observational study compared with a retrospective historical control. PATIENTS/PARTICIPANTS: Patients older than 60 years who received perioperative FIRA were compared with a historical cohort not receiving FIRA. SETTING: This study was conducted at a Level 1 trauma center. MAIN OUTCOME MEASUREMENTS: The primary outcome was morphine milliequivalents (MME) consumed during the index hospitalization. Fracture pattern-specific preoperative and postoperative MME consumption and surgical procedure-specific postoperative MME consumption was compared between the FIRA and non-FIRA groups. RESULTS: A total of 949 patients were included in this study, with 194 (20.4%) patients in the prospective protocol group. There were no baseline differences between cohorts. Preoperatively, only femoral neck fracture patients receiving FIRA used fewer MME (P < 0.001). Postoperatively, femoral neck fracture patients receiving FIRA used fewer MME on postoperative day (POD) 1 (P = 0.027) and intertrochanteric fracture patients used fewer MME on POD1 and POD2 (P = 0.013; P = 0.002). Cephalomedullary nail patients receiving FIRA used fewer MME on POD1 and POD2 (P = 0.004; P = 0.003). Hip arthroplasty patients receiving FIRA used fewer MME on POD1 (P = 0.037). Percutaneous pinning and sliding hip screw patients had no significant MME reduction from FIRA. CONCLUSIONS: Preoperatively, patients with femoral neck fractures benefit most from FIRA. Postoperatively, both patients with femoral neck fractures and intertrochanteric fractures benefit from FIRA. Patients undergoing cephalomedullary nail fixation or hip arthroplasty benefit most from FIRA postoperatively. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

A Comparison in Outcomes of Preoperative Single-shot versus Continuous Catheter Fascia Iliaca Regional Anesthesia in Geriatric Hip Fracture Patients.

BACKGROUND: Fascia iliaca nerve blocks relieve pain in geriatric hip fracture patients and can be administered via a single-shot or continuous catheter. We compared perioperative opioid consumption and pain scores between these two blocks. METHODS: We performed a prospective, observational cohort study, including geriatric hip fracture patients who received a preoperative block. We compared morphine milligram equivalent (MME) consumption and visual analog scale (VAS) pain scores between single-shot and continuous fascia iliaca blocks at multiple time points: preoperative and on postoperative (POD) day 0, 1, and 2. We compared the change in preoperative total and hourly opioid consumption before and after block placement within and between groups. Secondary outcomes included opioid related adverse events, length of stay, and readmission rates. RESULTS: 107 patients were analyzed, 66 received a single-shot and 41 a continuous block. No significant differences were found between both blocks at any time point for median MME consumption or pain scores. MME [IQR]: preoperative 20.5 [6.0,48.8] vs. 24.0 [8.8,48.0], p=0.95; POD0 6.0 [0.0,18.6] vs. 10.0 [0.0,14.0], p=0.52; POD1 12.0 [0.0,30.0] vs. 18.0 [5.0,24.0], p=0.69; POD2 6.0 [0.0,21.2] vs. 12.0 [0.0,24.0], p=0.54. VAS [IQR]: preoperative 4.0 [2.2,5.3] vs. 4.6 [3.2,5.3], p=0.34; POD0 1.3 [0.0,3.7] vs. 2.5 [0.0,3.6], p=0.73; POD1 2.9 [1.7,4.4] vs. 3.7 [1.5,4.7], p=0.59; POD2 2.4 [1.0,4.4] vs. 3.3 [1.9,4.2], p=0.18. Preoperative MME/hr significantly decreased after the block for both groups: 1.05 [0.0,2.2] to 0.0 [0.0,0.0], p < 0.001; 1.4 [0.6,3.1] to 0.0 [0.0,0.1], p < 0.001. The reduction in MME/hr between groups was not significantly different: 0.9 [0.0,1.9] vs. 1.4 [0.6,3.1], p = 0.067. We found no significant differences in secondary outcomes between groups. CONCLUSIONS: We report no differences in opioid use and pain scores between single-shot and continuous catheter fascia iliaca nerve blocks. Both blocks similarly reduce preoperative opioid consumption.

Time to Block: Early Regional Anesthesia Improves Pain Control in Geriatric Hip Fractures.

BACKGROUND: Fascia iliaca nerve blocks (FIBs) anesthetize the thigh and provide opioid-sparing analgesia for geriatric patients with hip fracture awaiting a surgical procedure. FIBs are recommended for preoperative pain management; yet, block administration is often delayed for hours after admission, and delays in pain management lead to worse outcomes. Our objective was to determine whether opioid consumption and pain following a hip fracture are affected by the time to block (TTB). We also examined length of stay and opioid-related adverse events. METHODS: This prospective cohort study included patients who were ≥60 years of age, presented with a hip fracture, and received a preoperative FIB from March 2017 to December 2017. Individualized care timelines, including the date and time of admission, block placement, and surgical procedure, were created to evaluate the effect that TTB and time to surgery (TTS) had on outcomes. Patterns among TTB, TTS, and morphine milligram equivalents (MME) were investigated using the Spearman rho correlation. For descriptive purposes, we divided patients into 2 groups based on the median TTB. Multivariable regression for preoperative MME and length of stay was performed to assess the effect of TTB. RESULTS: There were 107 patients, with a mean age of 83.3 years, who received a preoperative FIB. The median TTB was 8.5 hours. Seventy-two percent of preoperative MME consumption occurred before block placement (pre-block MME). A longer TTB was most strongly correlated with pre-block MME (rho = 0.54; p < 0.001), and TTS was not correlated. Patients with a faster TTB consumed fewer opioids preoperatively (12.0 compared with 33.1 MME; p = 0.015), had lower visual analog scale scores for pain on postoperative day 1 (2.8 compared with 3.5 points; p = 0.046), and were discharged earlier (4.0 compared with 5.5 days; p = 0.039). There were no differences in preoperative pain scores, postoperative opioid consumption, delirium, or opioid-related adverse events. Multivariate regression showed that every hour of delay in TTB was associated with a 2.8% increase in preoperative MME and a 1.0% increase in the length of stay. CONCLUSIONS: Faster TTB in geriatric patients with hip fracture may reduce opioid use, pain, and length of stay. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Subchondral lucencies of the proximal tibia in 17 horses.

OBJECTIVE: To describe subchondral lucencies (SCL) in the equine proximal tibia, several treatment options, and clinical outcomes. STUDY DESIGN: Retrospective study. ANIMALS: Seventeen horses with proximal tibial SCL. METHODS: Medical record and radiograph review. Follow-up was obtained via examination and radiography when possible and by telephone and race records when required. The median duration of follow-up was 20 months (range, 0-48). RESULTS: Proximal tibial SCL were associated with lameness in 14 of 17 horses. Subchondral lucencies were primary in 11 horses and secondary to an ipsilateral medial femoral condyle SCL in six horses. One foal with a primary SCL was euthanized because of osteomyelitis. Six horses ≤1 year old with primary SCL were managed with exercise restrictions only; SCL in three horses without lameness decreased in size, whereas three horses with lameness did not improve. One young horse treated with surgical debridement failed to improve and was euthanized. Lameness resolved in three horses with primary tibial SCL treated with screw fixation. Screw fixation of secondary SCL in five horses led to a reduction in SCL size and degree of lameness. CONCLUSION: Primary tibial SCL healed with rest in 3 non-lame young horses with small SCL, but was not successful in lame horses with larger SC. Radiographic size and associated lameness improved or resolved with screw fixation in primary and secondary proximal tibial SCL. CLINICAL SIGNIFICANCE: Primary tibial SCL that did not cause lameness healed with conservative management, but persistent primary and secondary tibial SCL required screw fixation to reduce lameness.

Stand-alone Anterior Lumbar Interbody, Transforaminal Lumbar Interbody, and Anterior/Posterior Fusion: Analysis of Fusion Outcomes and Costs.

Fusion outcomes and costs of stand-alone anterior lumbar interbody fusion (ALIF), transforaminal lumbar interbody fusion (TLIF) in association with posterior fusion, and anterior/posterior (A/P) fusion were compared using clinical, radiographic, and billing data. Adult patients with symptomatic 1- or 2-level degenerative disk disease in isolation or in association with a grade 1 or 2 degenerative or lytic spondylolisthesis and canal and/or foraminal stenosis who underwent elective stand-alone ALIF, TLIF, or A/P fusion were compared. The analysis focused primarily on fusion rates and costs and secondarily on radiographic and clinical parameters. One hundred six patients at least 2 years beyond surgery (ALIF, 53; TLIF, 17; A/P fusion, 36) were reviewed. Demographics were similar except for age, with the ALIF group being younger (mean, 37.8 years) than the other groups (TLIF, 53.1 years; A/P fusion, 48.2 years). There were no differences between the groups in fusion rates or outcomes as assessed by the Numeric Rating Scale. Compared with the other 2 groups, the ALIF group had a significantly shorter operative time, less blood loss, and a shorter stay (P<.0001). Evaluation of radiographic parameters revealed significant differences regarding disk angle (P<.001), disk height (P<.0001), and pelvic tilt (P=.001) favoring ALIF and A/P fusion over TLIF. Stand-alone ALIF should be considered in the management of patients with 1- or 2-level lumbar degenerative disk disease for which the pathology can be addressed adequately via this approach. [Orthopedics. 2018; 41(5):e655-e662.].

Allografts for Ligament Reconstruction: Where Are We Now?

The use of musculoskeletal allografts by orthopedic surgeons continues to rise. The process of procuring and sterilizing allografts is evolving with much consideration to limiting the spread of infectious diseases and preserving tissue integrity. Research involving the application of allografts, particularly for ligament repair, is quite active, necessitating an update for the practicing orthopedist. Avoiding donor site morbidities is one of the most commonly cited advantages of allografts over autografts. There is controversy amongst studies for allografts in terms of their biological incorporation and clinical outcomes compared to autografts. This article focuses on reviewing the most current literature and usage of allograft tissue for ligamentous reconstruction amongst orthopedic surgeons today. It includes an in-depth analysis of the current processing, handling, and safety standards employed today, in addition to the advantages and disadvantages of allograft use.

Short-term results of percutaneous treatment of acetabular fractures: functional outcomes, radiographic assessment and complications.

PURPOSE: Our purpose was to assess functional outcomes, radiographic characteristics and complications in patients who underwent fixation of acetabular fracture using percutaneous means only. METHODS: This was a retrospective cohort study of adult patients with an acetabular fracture admitted to a level 1 trauma centre and treated with closed reduction and percutaneous fixation. Nineteen patients were identified, and mechanism of injury, radiologic classification of fracture, complications and functional outcomes were analysed. Outcome measurements included Patient Reported Outcomes Measurement Information System (PROMIS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores, which are validated patient questionnaires assessing functional outcome. They are scored as a point range on a per-question basis, with a combined range possibility of 0-96 for WOMAC and 5-75 for PROMIS. RESULTS: Nineteen patients over a two year period were reviewed. Fracture displacement improved following surgery from a mean 7.3 mm (range 0-33 mm) to 2.6 mm (range 0-12 mm). Complications included one post-operative death from non-ST-segment elevation myocardial infarction, sciatic nerve injury, malpositioned screw and deep infection. There were no vascular injuries, pulmonary emboli or deep venous thromboses. Of the 19 patients eligible for the study, seven completed both PROMIS mobility and WOMAC osteoarthritis questionnaires at a mean follow-up of 572 days (1.57 years), with a range of 435-862 days. The average WOMAC score was 7.4 (range 0-30) and mean PROMIS score 66.4 (range 50-75). CONCLUSIONS: Functional outcomes in this study are comparable with other published studies and support percutaneous management of acetabular fractures as an effective alternative to open reduction and internal fixation.

Preliminary investigation of the treatment of equine medial femoral condylar subchondral cystic lesions with a transcondylar screw.

OBJECTIVE: To determine if medial femoral condylar (MFC) subchondral cystic lesions (SCL) causing lameness will demonstrate radiographic evidence of healing and lameness reduction after placement of a transcondylar screw in lag fashion. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 20) with lameness attributed to a MFC SCL. METHODS: A 4.5 mm screw was inserted in lag fashion across MFC SCL in horses with hindlimb lameness. Post-operative radiography and lameness examinations were performed at 30-60 day intervals after surgery for 120 days, and SCL radiographic area and lameness were graded. Treatment was considered successful if lameness was eliminated and the radiographic area of the SCL on a caudocranial projection decreased ≥ 50% by 120 days. RESULTS: Twenty-six limbs were treated. Nine horses (11 limbs) had autologous adjunctive biologics placed into the SCL. Lameness was reduced by 1-2 grades by 60 days after surgery in 18 horses and was eliminated in 15 horses by 120 days, at which time the SCL area had decreased ≥ 50% and work had resumed without lameness (mean follow-up, 12 months). Biologic therapies had no impact on treatment success. Treatment was less successful in horses >3 years of age. CONCLUSIONS: A MFC transcondylar screw decreases the area of a MFC SCL on craniocaudal radiographs and eliminates lameness in ∼ 75% of horses by 120 days. The simplicity and lack of specialized equipment required make this technique a useful option for the treatment of equine SCL causing lameness.

Aerobic fitness and intra-individual variability of neurocognition in preadolescent children.

This study examined behavioral and neuroelectric intra-individual variability (IIV) in preadolescent children during a task requiring variable amounts of cognitive control. The current study further examined whether IIV was moderated by aerobic fitness level. Participants performed a modified flanker task, comprised of congruent and incongruent arrays, within compatible and incompatible stimulus-response conditions. Results revealed that congruent, relative to incongruent, conditions were associated with less IIV of RT. Further, less IIV of RT, P3 amplitude, and P3 latency was observed for the compatible relative to the incompatible condition. Higher fitness was associated with shorter and less variable RT only for the incompatible condition, with no fitness-related differences observed for P3 variability. The findings suggest that conditions requiring greater cognitive control are associated with increased IIV, and that higher fitness may be associated with greater integrity of cognitive control systems during development.

From ERPs to academics.

Standardized tests have been used to forecast scholastic success of school-age children, and have been related to intelligence, working memory, and inhibition using neuropsychological tests. However, ERP correlates of standardized achievement have not been reported. Thus, the relationship between academic achievement and the P3 component was assessed in a sample of 105 children during performance on a Go/NoGo task. The Wide Range Achievement Test - 3rd edition was administered to assess aptitude in reading, spelling, and arithmetic. Regression analyses indicated an independent contribution of P3 amplitude to reading and arithmetic achievement beyond the variance accounted for by IQ and school grade. No such relationship was observed for spelling. These data suggest that the P3, which reflects attentional processes involved in stimulus evaluation and inhibitory control may be a biomarker for academic achievement during childhood.

Childhood aerobic fitness predicts cognitive performance one year later.

Aerobically fit children outperform less fit peers on cognitive control challenges that involve inhibition, cognitive flexibility, and working memory. The aim of this study was to determine whether, compared with less fit children, more fit 9- and 10-year-old pre-adolescents exhibit superior performance on a modified compatible and incompatible flanker task of cognitive control at the initial time of fitness testing and approximately one year later. We found that more fit children demonstrated increased flanker accuracy at both test sessions, coupled with a superior ability to flexibly allocate strategies during task conditions that required different amounts of cognitive control, relative to less fit children. More fit children also gained a speed benefit at follow-up testing. Structural MRI data were also collected to investigate the relationship between basal ganglia volume and task performance. Bilateral putamen volumes of the dorsal striatum and globus pallidus volumes predicted flanker performance at initial and follow-up testing one year later. The present findings suggest that childhood aerobic fitness and basal ganglia volumes relate to cognitive control at the time of fitness testing and may play a role in cognitive performance in the future. We hope that this research will encourage public health and educational changes that will promote a physically active lifestyle in children.

The top 10 challenges in extreme-scale visual analytics.

A team of scientists and researchers discusses the top 10 challenges in extreme-scale visual analytics (VA). The discussion covers applying VA technologies to both scientific and nonscientific data, evaluating the problems and challenges from both technical and social perspectives.

Racing and sales performance after unilateral or bilateral single transphyseal screw insertion for varus angular limb deformities of the carpus in 53 thoroughbreds.

OBJECTIVE: To evaluate the racing and sales performance of Thoroughbred horses with varus angular limb deformities of the carpus treated by unilateral or bilateral single transphyseal screw (STS) placement. STUDY DESIGN: Case series. ANIMALS: Thoroughbred horses (n=53). METHODS: Medical records (January 1, 2005-December 31, 2006) of yearling Thoroughbreds treated for carpal angular limb deformity by transphyseal screw insertion in the distal aspect of the radius were reviewed. Retrieved data were sex, surgery, and screw removal dates, surgical site, appearance, limb(s) affected, type of angular limb deformity, and degree of angular deviation measured by a goniometer. Racing and sales data were collected for analysis from an online racing site for all treated horses and their maternal siblings. RESULTS: No significant differences were identified between treated horses and their maternal siblings in yearling sale price, 2-year-olds in training sale price, percent starters, percent winners, and starts, earnings, and earnings/start made during the 2- and 3-year old years. CONCLUSIONS: No deleterious effects on sales or racing performance were identified after use of STS in the distal aspect of the radius of Thoroughbreds for the treatment of varus angular limb deformities of the carpus.

Cardiorespiratory fitness and the flexible modulation of cognitive control in preadolescent children.

The influence of cardiorespiratory fitness on the modulation of cognitive control was assessed in preadolescent children separated into higher- and lower-fit groups. Participants completed compatible and incompatible stimulus-response conditions of a modified flanker task, consisting of congruent and incongruent arrays, while ERPs and task performance were concurrently measured. Findings revealed decreased response accuracy for lower- relative to higher-fit participants with a selectively larger deficit in response to the incompatible stimulus-response condition, requiring the greatest amount of cognitive control. In contrast, higher-fit participants maintained response accuracy across stimulus-response compatibility conditions. Neuroelectric measures indicated that higher-fit, relative to lower-fit, participants exhibited global increases in P3 amplitude and shorter P3 latency, as well as greater modulation of P3 amplitude between the compatible and incompatible stimulus-response conditions. Similarly, higher-fit participants exhibited smaller error-related negativity (ERN) amplitudes in the compatible condition, and greater modulation of the ERN between the compatible and incompatible conditions, relative to lower-fit participants who exhibited large ERN amplitudes across both conditions. These findings suggest that lower-fit children may have more difficulty than higher-fit children in the flexible modulation of cognitive control processes to meet task demands.

A photo- and electrochemically-active porphyrin-fullerene dyad electropolymer.

A hole- and electron-conducting polymer has been prepared by electropolymerization of a porphyrin-fullerene monomer. The porphyrin units are linked by aminophenyl groups to form a linear chain in which the porphyrin is an integral part of the polymer backbone. The absorption spectrum of a film formed on indium-tin-oxide-coated glass resembles that of a model porphyrin-fullerene dyad, but with significant peak broadening. The film demonstrates a first oxidation potential of 0.75 V vs. SCE, corresponding to oxidation of the porphyrin polymer, and a first reduction potential of -0.63 V vs. SCE, corresponding to fullerene reduction. Time-resolved fluorescence studies show that the porphyrin first excited singlet state is strongly quenched by photoinduced electron transfer to fullerene. Transient absorption investigations reveal that excitation generates mobile charge carriers that recombine by both geminate and nongeminate pathways over a large range of time scales. Similar studies on a related polymer that lacks the fullerene component show complex, laser-intensity-dependent photoinduced electron transfer behavior. The properties of the porphyrin-fullerene electropolymer suggest that it may be useful in organic photovoltaic applications, wherein light absorption leads to charge separation within picoseconds in a "molecular heterojunction" with no requirement for exciton migration.