Rejuvenating silicon probes for acute neurophysiology.

Neurophysiological recording with a new probe often yields better signal quality than with a used probe. Why does the signal quality degrade after only a few experiments? Here, we considered silicon probes in which the contacts are densely packed, and each contact is coated with a conductive polymer that increases its surface area. We tested 12 Cambridge Neurotech silicon probes during 61 recording sessions from the brain of three marmosets. Out of the box, each probe arrived with an electrodeposited polymer coating on 64 gold contacts and an impedance of around 50 kΩ. With repeated use, the impedance increased and there was a corresponding decrease in the number of well-isolated neurons. Imaging of the probes suggested that the reduction in signal quality was due to a gradual loss of the polymer coating. To rejuvenate the probes, we first stripped the contacts, completely removing their polymer coating, and then recoated them in a solution of 10 mM 3,4-Ethylenedioxythiophene (EDOT) monomer with 11 mM Poly(sodium 4-styrenesulfonate) (PSS) using a current density of about 3 mA/cm2 for 30 s. This recoating process not only returned probe impedance to around 50 kΩ but also yielded significantly improved signal quality during neurophysiological recordings. Thus, insertion into the brain promoted the loss of the polymer that coated the contacts of the silicon probes. This led to degradation of signal quality, but recoating rejuvenated the probes.NEW & NOTEWORTHY With repeated use, a silicon probe's ability to isolate neurons degrades. As a result, the probe is often discarded after only a handful of uses. Here, we demonstrate a major source of this problem and then produce a solution to rejuvenate the probes.

The Ethics of Procedural Education Under Pandemic Conditions.

BACKGROUND: The COVID-19 pandemic significantly disrupted emergency medicine residents' education. Early in the pandemic, many facilities lacked adequate personal protective equipment (PPE), and intubation was considered particularly high risk for transmission to physicians, leading hospitals to limit the number of individuals present during the procedure. This posed difficulties for residents and academic faculty, as opportunities to perform endotracheal intubation during residency are limited, but patients with COVID-19 requiring intubation are unstable and have difficult airways. Case Scenario: When PPE is being rationed, who should be the one to perform an intubation on a patient with respiratory failure from severe COVID-19? DISCUSSION: We examined this case scenario using the ethical frameworks of bioethical principles and virtue ethics. Bioethical principles include justice, beneficence, nonmalfeasance, and autonomy, and virtue ethics emphasizes the provision of moral exemplars and opportunities to exercise practical wisdom. Arguments for an attending-only strategy include the role of the attending as a truly autonomous decision maker and the importance of providing residents with a moral exemplar. A resident-only strategy benefits a resident's future patients and provides opportunities for residents to exercise character. Strategies preserving the dyad of attending and resident maintain these advantages and mitigate some drawbacks, while intubation teams may provide the most parsimonious use of PPE, but may elide resident involvement. CONCLUSIONS: There exist compelling motivations for involving senior residents and attendings in high-risk intubations during the COVID-19 pandemic. A just strategy will preserve residents' role whenever possible, while maximizing supervision and providing alternative routes for intubation practice.

Gender differences in funding among grant recipients in emergency medicine: A multicenter analysis.

OBJECTIVE: To describe differences in funded grants between male and female faculty in two academic emergency departments. METHODS: This was a retrospective analysis of grant funding at two academic emergency departments from January 2012-September 2018. We queried the grants department databases at each institution and obtained records of all funded grants for emergency medicine (EM) faculty. We extracted the following information for each award: gender of the principal investigator (PI), PI academic rank, grant mechanism (government, institutional, industry, organizational), and percent effort. Differences by gender were compared using Chi-square or Fisher's exact test and Wilcoxon-rank sum. RESULTS: One-hundred and thirty grants were awarded to EM faculty at the two institutions during the study period. Of the funded grants, 35 (27%) of recipients were female. Among grant recipients, females held lower academic ranking than males (p-value < 0.001): Instructor (49% vs 51%), Assistant Professor (36% vs 64%), Associate Professor (9% vs 91%), and Professor (0% vs 100%), respectively. Organizational grants were dispersed equally between funded faculty, but females received a fewer government, industry, and institutional grants (p-value = 0.007). Female grant recipients were awarded a higher median percent of effort compared to males (14% [IQR: 3-51] vs 8% [IQR: 1-15], respectively, p-value = 0.023). CONCLUSION: In this multicenter analysis, gender discrepancies exist among funded grants of EM faculty. Male recipients had higher academic ranking than their female counterparts. Female recipients were less likely to have government, institutional, and industry grants but received a greater percent effort on funding that was awarded.

Kidney Transplantation in HIV-Positive Patients: A Single-Center, 16-Year Experience.

Hahnemann University Hospital has performed 120 kidney transplantations in human immunodeficiency virus (HIV)-positive individuals during the last 16 years. Our patient population represents ∼10% of the entire US population of HIV-positive kidney recipients. In our earlier years of HIV transplantation, we noted increased rejection rates, often leading to graft failure. We have established a multidisciplinary team and over the years have made substantial protocol modifications based on lessons learned. These modifications affected our approach to candidate evaluation, donor selection, perioperative immunosuppression, and posttransplantation monitoring and resulted in excellent posttransplantation outcomes, including 100% patient and graft survival at 1 year and patient and graft survival at 3 years of 100% and 96%, respectively. We present key clinical data, including a granular patient-level analysis of the associations of antiretroviral therapy regimens with long-term survival, cellular and antibody-mediated rejection rates, and the causes of allograft failures. In summary, we provide details on the evolution of our approach to HIV transplantation during the last 16 years, including strategies that may improve outcomes among HIV-positive kidney transplantation candidates throughout the United States.

The effect of transfer to adult transplant care on kidney function and immunosuppressant drug level variability in pediatric kidney transplant recipients.

Adolescent age at time of transplant has been recognized as a risk factor for renal allograft loss. Increased risk for graft failure may persist from adolescence to young adulthood. Transfer of care is hypothesized as a risk factor for non-adherence and graft loss. We explored whether kidney allograft function declined at an accelerated rate after transfer of care to adult transplant centers and whether coefficient of variation of tacrolimus (CV TAC) trough levels predicted allograft loss. Single-center, retrospective chart review was performed for pediatric kidney transplant recipients who received transplants between 1999 and 2011. Change in eGFR pre- and post-transfer was performed via a linear mixed-effects model. CV TAC was calculated in transplant recipients with TAC data pre- and post-transfer. t test was performed to determine the difference between means of CV TAC in subjects with and without allograft loss following transfer of care. Of the 138 subjects who transferred to adult care, 47 subjects with data pre- and post-transfer demonstrated a decrease in the rate of eGFR decline post-transfer from 8.0 mL/min/1.73 m2 per year to 2.1 mL/min/1.73 m2 per year, an ~80% decrease in eGFR decline post-transfer (P = 0.01). Twenty-four subjects had CV TAC data pre- and post-transfer of care. Pretransfer CV TAC for subjects with allograft loss post-transfer was significantly higher than in subjects without allograft loss (49% vs 26%, P < 0.05). Transfer of care was not independently associated with acceleration in eGFR decline. CV TAC may aid in identifying patients at risk for allograft loss post-transfer.

Lidar thermometry using two-line atomic fluorescence.

In this work, Scheimpflug lidar has been combined with the thermometric technique two-line atomic fluorescence, to carry out stand-off, spatially resolved temperature measurements. Indium atoms were seeded into a modified Perkin-Elmer-burner and two tunable single-mode diode lasers with their wavelengths tuned to 410.17 and 451.12 nm were used to excite the seeded atoms. The fluorescence signal was collected using both a line-scan detector and a two-dimensional intensified CCD camera. One-dimensional flame temperature profiles were measured at different heights above a porous-plug burner, located at a distance of 1.5 m from the lidar system. The technique was also used to demonstrate two-dimensional temperature measurements in the same flame. The accuracy of the measured temperature was found to be limited mainly by uncertainty in the spectral overlap between the laser emission and the indium atom absorption spectrum as well as uncertainty in laser power measurements. With the constraint that indium can be introduced into the measurement volume, it is anticipated that the developed measurement concept could constitute a valuable tool, allowing in situ spatially resolved thermometry in intractable industrial applications, sufferings from limited optical access, thus requiring remote single-optical-port sensing.

Spatial Mapping of Protein Adsorption on Mesoporous Silica Nanoparticles by Stochastic Optical Reconstruction Microscopy.

Exposure to biological fluid envelops a nanoparticle in layers of proteins and biomolecules, which has a profound impact on the nanoparticle's biological fate. Although the identities and amounts of the proteins in this "corona" have been thoroughly examined, the spatial arrangement of the proteins is unclear, a problem that is compounded on porous nanoparticles due to penetration of proteins within the porous network. To address this problem, we have developed a procedure based on information derived from stochastic optical reconstruction microscopy. We employed a mathematical model to reveal the penetration depth of several proteins within porous nanoparticles. Understanding protein penetration depth provides an explanation for the composition of the protein corona, aiding in the development of safe and effective particle-based therapies.

Association of tenofovir disoproxil fumarate with primary allograft survival in HIV-positive kidney transplant recipients.

BACKGROUND: Tenofovir disoproxil fumarate (TDF) is an antiretroviral agent frequently used to treat human immunodeficiency virus (HIV). There are concerns regarding its potential to cause acute kidney injury, chronic kidney disease, and proximal tubulopathy. Although TDF can effectively suppress HIV after kidney transplantation, it is unknown whether use of TDF-based antiretroviral therapy (ART) after kidney transplantation adversely affects allograft survival. METHODS: We examined 104 HIV+ kidney transplant (KT) recipients at our center between 2001 and 2014. We generated a propensity score for TDF treatment using recipient and donor characteristics. We then fit Cox proportional hazards models to investigate the association between TDF treatment and 3-year, death-censored primary allograft failure, adjusting for the propensity score and delayed graft function (DGF). RESULTS: Of the 104 HIV+ KT candidates who underwent transplantation during the study period, 23 (22%) were maintained on TDF-based ART at the time of transplantation, and 81 (78%) were on non-TDF-based ART. Median age of the cohort was 48 years; 87% were male; 88% were black; and median CD4 count at transplantation was 450 cells/mm3 . Median kidney donor risk index was 1.2. At 3 years post transplantation, primary allograft failure occurred in 26% of patients on TDF-based ART and in 28% of patients on non-TDF-based ART (P=.5). TDF treatment was not associated with primary allograft failure at 3 years post transplant after adjusting for DGF and a propensity score for TDF use (hazard ratio 2.12, 95% confidence interval 0.41-10.9). CONCLUSIONS: In a large single-center experience of HIV+ kidney transplantation, TDF use following kidney transplantation was not significantly associated with primary allograft failure. These results may help inform management for HIV+ KT recipients in need of TDF therapy for adequate viral suppression.

Cultural Competency Training in Emergency Medicine.

BACKGROUND: The Emergency Department is widely regarded as the epicenter of medical care for diverse and largely disparate types of patients. Physicians must be aware of the cultural diversity of their patient population to appropriately address their medical needs. A better understanding of residency preparedness in cultural competency can lead to better training opportunities and patient care. OBJECTIVE: The objective of this study was to assess residency and faculty exposure to formal cultural competency programs and assess future needs for diversity education. METHODS: A short survey was sent to all 168 Accreditation Council for Graduate Medical Education program directors through the Council of Emergency Medicine Residency Directors listserv. The survey included drop-down options in addition to open-ended input. Descriptive and bivariate analyses were used to analyze data. RESULTS: The response rate was 43.5% (73/168). Of the 68.5% (50/73) of residency programs that include cultural competency education, 90% (45/50) utilized structured didactics. Of these programs, 86.0% (43/50) included race and ethnicity education, whereas only 40.0% (20/50) included education on patients with limited English proficiency. Resident comfort with cultural competency was unmeasured by most programs (83.6%: 61/73). Of all respondents, 93.2% (68/73) were interested in a universal open-source cultural competency curriculum. CONCLUSIONS: The majority of the programs in our sample have formal resident didactics on cultural competency. Some faculty members also receive cultural competency training. There are gaps, however, in types of cultural competency training, and many programs have expressed interest in a universal open-source tool to improve cultural competency for Emergency Medicine residents.

MODFLOW as a Configurable Multi-Model Hydrologic Simulator.

MODFLOW 6 is the latest in a line of six "core" versions of MODFLOW released by the U.S. Geological Survey. The MODFLOW 6 architecture supports incorporation of additional hydrologic processes, in addition to groundwater flow, and allows interaction between processes. The architecture supports multiple model instances and multiple types of models within a single simulation, a flexible approach to formulating and solving the equations that represent hydrologic processes, and recent advances in interoperability, which allow MODFLOW to be accessed and controlled by external programs. The present version of MODFLOW 6 consolidates popular capabilities available in MODFLOW variants, such as the unstructured grid support in MODFLOW-USG, the Newton-Raphson formulation in MODFLOW-NWT, and the support for partitioned stress boundaries in MODFLOW-CDSS. The flexible multi-model capability allows users to configure MODFLOW 6 simulations to represent the local-grid refinement (LGR) capabilities available in MODFLOW-LGR, the multi-species transport capabilities in MT3DMS, and the coupled variable-density capabilities available in SEAWAT. This paper provides a new, holistic and integrated overview of simulation capabilities made possible by the MODFLOW 6 architecture, and describes how ongoing and future development can take advantage of the program architecture to integrate new capabilities in a way that is minimally invasive and automatically compatible with the existing MODFLOW 6 code.

Optical diagnostics of a gliding arc.

Dynamic processes in a gliding arc plasma generated between two diverging electrodes in ambient air driven by 31.25 kHz AC voltage were investigated using spatially and temporally resolved optical techniques. The life cycles of the gliding arc were tracked in fast movies using a high-speed camera with framing rates of tens to hundreds of kHz, showing details of ignition, motion, pulsation, short-cutting, and extinction of the plasma column. The ignition of a new discharge occurs before the extinction of the previous discharge. The developed, moving plasma column often short-cuts its current path triggered by Townsend breakdown between the two legs of the gliding arc. The emission from the plasma column is shown to pulsate at a frequency of 62.5 kHz, i.e., twice the frequency of the AC power supply. Optical emission spectra of the plasma radiation show the presence of excited N2, NO and OH radicals generated in the plasma and the dependence of their relative intensities on both the distance relative to the electrodes and the phase of the driving AC power. Planar laser-induced fluorescence of the ground-state OH radicals shows high intensity outside the plasma column rather than in the center suggesting that ground-state OH is not formed in the plasma column but in its vicinity.

Under-represented minorities in emergency medicine.

BACKGROUND: According to the Association of American Medical Colleges and the Institute of Medicine, promoting diversity in the health care workforce is a national priority. The under-representation of minorities in health care contributes significantly to the problem of health disparities currently facing racial and ethnic minority groups in the United States (US). Evidence shows that improved diversity among medical providers contributes to higher satisfaction for minority patients and better educational experiences for trainees. OBJECTIVE: Our aim was to describe the racial and ethnic composition of medical students, Emergency Medicine residents, and practicing Emergency Medicine Physicians as compared with other specialties and the US population. METHODS: A cross-sectional analysis of the most recent data available from the Association of American Medical Colleges and the US Census were used to determine the racial and ethnic distribution of the US population, medical students, residents, and practicing physicians. The Association of American Medical Colleges' definition of under-represented minorities (URMs) for the years studied included individuals of black, Latino, and Native-American race and ethnicity. Proportions with 95% confidence intervals were calculated. χ(2) analysis was used to compare groups. RESULTS: URMs comprised 30% of the total US population, yet only 6% of all practicing physicians and 9% of Emergency Physicians self-identified as URMs. By comparison, 15% of medical students, 17% of all residents, and 14% of Emergency Medicine residents were URMs (p < 0.0001). CONCLUSIONS: Emergency Medicine, like other specialties, lacks the racial and ethnic diversity seen in the US population. Efforts to improve diversity at the resident level are limited by the number of URM students in medical school, and should include steps aimed at addressing this issue.

Racial disparities in emergency medicine: Implementation of a novel educational module in the emergency medicine clerkship.

Objectives: Despite decades of literature recognizing racial disparities (RDs) in emergency medicine (EM), published curricula dedicated to addressing them are sparse. We present details of our novel RD curriculum for EM clerkships and its educational outcomes. Methods: We created a 30-min interactive didactic module on the topic designed for third- and fourth-year medical students enrolled in our EM clerkships. Through a modified Delphi process, education faculty and content experts in RD developed a 10-question multiple-choice test of knowledge on RD that the students completed immediately prior to and 2 weeks following the activity. Students also completed a Likert-style learner satisfaction survey. Median pre- and posttest scores were compared using a paired Wilcoxon signed-rank test and presented using medians and 95% confidence intervals (CIs). Satisfaction survey responses were dichotomized into favorable and neutral/not favorable. Results: For the 36 students who completed the module, the median pretest score was 40% (95% CI 36%-50%) and the posttest score was 70% (95% CI 60%-70%) with a p-value of <0.001. Thirty-five of the 36 students improved on the posttest with a mean increase of 24.2% (95% CI 20.2-28.2). The satisfaction survey also showed a positive response, with at least 83% of participants responding favorably to all statements (overall mean favorable response 93%, 95% CI 90%-96%).ConclusionsThis EM-based module on RD led to improvement in students' knowledge on the topic and positive reception by participants. This is a feasible option for educating students in EM on the topic of RD.

Race and Ethnicity and Primary Language in Emergency Department Triage.

Importance: Emergency department (ED) triage substantially affects how long patients wait for care but triage scoring relies on few objective criteria. Prior studies suggest that Black and Hispanic patients receive unequal triage scores, paralleled by disparities in the depth of physician evaluations. Objectives: To examine whether racial disparities in triage scores and physician evaluations are present across a multicenter network of academic and community hospitals and evaluate whether patients who do not speak English face similar disparities. Design, Setting, and Participants: This was a cross-sectional, multicenter study examining adults presenting between February 28, 2019, and January 1, 2023, across the Mass General Brigham Integrated Health Care System, encompassing 7 EDs: 2 urban academic hospitals and 5 community hospitals. Analysis included all patients presenting with 1 of 5 common chief symptoms. Exposures: Emergency department nurse-led triage and physician evaluation. Main Outcomes and Measures: Average Triage Emergency Severity Index [ESI] score and average visit work relative value units [wRVUs] were compared across symptoms and between individual minority racial and ethnic groups and White patients. Results: There were 249 829 visits (149 861 female [60%], American Indian or Alaska Native 0.2%, Asian 3.3%, Black 11.8%, Hispanic 18.8%, Native Hawaiian or Other Pacific Islander <0.1%, White 60.8%, and patients identifying as Other race or ethnicity 5.1%). Median age was 48 (IQR, 29-66) years. White patients had more acute ESI scores than Hispanic or Other patients across all symptoms (eg, chest pain: Hispanic, 2.68 [95% CI, 2.67-2.69]; White, 2.55 [95% CI, 2.55-2.56]; Other, 2.66 [95% CI, 2.64-2.68]; P < .001) and Black patients across most symptoms (nausea/vomiting: Black, 2.97 [95% CI, 2.96-2.99]; White: 2.90 [95% CI, 2.89-2.91]; P < .001). These differences were reversed for wRVUs (chest pain: Black, 4.32 [95% CI, 4.25-4.39]; Hispanic, 4.13 [95% CI, 4.08-4.18]; White 3.55 [95% CI, 3.52-3.58]; Other 3.96 [95% CI, 3.84-4.08]; P < .001). Similar patterns were seen for patients whose primary language was not English. Conclusions and Relevance: In this cross-sectional study, patients who identified as Black, Hispanic, and Other race and ethnicity were assigned less acute ESI scores than their White peers despite having received more involved physician workups, suggesting some degree of mistriage. Clinical decision support systems might reduce these disparities but would require careful calibration to avoid replicating bias.

Quantitative 3D imaging of scattering media using structured illumination and computed tomography.

An imaging technique capable of measuring the extinction coefficient in 3D is presented and demonstrated on various scattering media. The approach is able to suppress unwanted effects due to both multiple scattering and light extinction, which, in turbid situations, seriously hampers the performance of conventional imaging techniques. The main concept consists in illuminating the sample of interest with a light source that is spatially modulated in both the vertical and horizontal direction and to measure, using Structured Illumination, the correct transmission in 2D at several viewing angles. The sample is then reconstructed in 3D by means of a standard Computed Tomography algorithm. To create the adequate illumination, a novel "crossed" structured illumination approach is implemented. In this article, the accuracy and limitation of the method is first evaluated by probing several homogeneous milk solutions at various levels of turbidity. The unique possibility of visualizing an object hidden within such solutions is also demonstrated. Finally the method is applied on two different inhomogeneous scattering spray systems; one transient and one quasi-steady state.

Analysis of multiple scattering suppression using structured laser illumination planar imaging in scattering and fluorescing media.

The accuracy, precision and limitations of the imaging technique named Structured Laser Illumination Planar Imaging (SLIPI) have been investigated. SLIPI, which allows multiply scattered light to be diminished, has previously demonstrated improvements in image quality and contrast for spray imaging. In the current study the method is applied to a controlled confined environment consisting of a mixture of water and monodisperse polystyrene microspheres. Elastic scattering and fluorescence are studied and the results obtained when probing different particle concentrations and diameters conclusively show the advantages of SLIPI for imaging within moderately turbid media. Although the technique presents both good repeatability and agreement with the Beer-Lambert law, discrepancies in its performance were, however, discovered. Photons undergoing scattering without changing their incident trajectory cannot be discriminated and, owing to differences in scattering phase functions, probing larger particles reduces the suppression of multiply scattered light. However, in terms of visibility such behavior is beneficial as it allows denser media to be probed. It is further demonstrated that the suppression of diffuse light performs equally well regardless of whether photons propagate along the incident direction or towards the camera. In addition, this filtering process acts independently on the spatial distribution of the multiply scattered light but is limited by the finite dynamic range and unavoidable signal noise of the camera.

Management of stage I and II thymoma.

With a knowledgeable assessment of the clinical presentation and demographic and radiologic characteristics, most thymomas can be reliably identified preoperatively without the need for a biopsy. Surgery is the mainstay of treatment for stage I and II thymoma. The rate of complete resection is essentially 100% by open techniques, and recurrences are rare. A complete thymectomy via a sternotomy is the standard approach. Adjuvant radiotherapy after a complete resection does not appear to be of benefit. In the rare event of a recurrence, an aggressive approach should be taken with re-resection whenever possible.

Integrating Health Equity Content Into Health Professions Education.

Health equity is a common theme discussed in health professions schools, yet many educators are wary of addressing it. Avoidance of health equity content in health professions education leads to student frustration and missed opportunities to educate the next generation of health care professionals about sensitive yet important issues. Moreover, this gap in students' knowledge can negatively influence patients and perpetuate disparities.