Increased COVID-19 mortality among immigrants compared with US-born individuals: a cross-sectional analysis of 2020 mortality data

OBJECTIVE

Multiple studies have shown that racially minoritized groups had disproportionate COVID-19 mortality relative to non-Hispanic White individuals. However, there is little known regarding mortality by immigrant status nationally in the United States, despite being another vulnerable population.

STUDY DESIGN

This was an observational cross-sectional study using mortality vital statistics system data to calculate proportionate mortality ratios (PMRs) and mortality rates due to COVID-19 as the underlying cause.

METHODS

Rates were compared by decedents' identified race, ethnicity (Hispanic vs non-Hispanic), and immigrant (immigrants vs US born) status. Asian race was further disaggregated into "Asian Indian," "Chinese," "Filipino," "Japanese," "Korean," and "Vietnamese."

RESULTS

Of the over 3.4 million people who died in 2020, 10.4% of all deaths were attributed to COVID-19 as the underlying cause (n = 351,530). More than double (18.9%, n = 81,815) the percentage of immigrants who died of COVID-19 compared with US-born decedents (9.1%, n = 269,715). PMRs due to COVID-19 were higher among immigrants compared with US-born individuals for non-Hispanic White, non-Hispanic Black, Hispanic, and most disaggregated Asian groups. Among disaggregated Asian immigrants, age- and sex-adjusted PMR due to COVID-19 ranged from 1.58 times greater mortality among Filipino immigrants (95% confidence interval [CI]: 1.53, 1.64) to 0.77 times greater mortality among Japanese immigrants (95% CI: 0.68, 0.86). Age-adjusted mortality rates were also higher among immigrant individuals compared with US-born people.

CONCLUSIONS

Immigrant individuals experienced greater mortality due to COVID-19 compared with their US-born counterparts. As COVID-19 becomes more endemic, greater clinical and public health efforts are needed to reduce disparities in mortality among immigrants compared with their US-born counterparts.

The persistence of emamectin benzoate in marine sediments with different organic matter regimes, temperature conditions, and antibiotic presence

The objectives of this 318-day study are to determine half-lives of the anti-sea lice medication emamectin benzoate (EMB) under conditions present in sediments at aquaculture sites and document the degradation of EMB into its main metabolite desmethyl emamectin benzoate (DES). Tested conditions include different matrix types (sand, mud), two temperatures (4, 10 degrees), organic matter presence (fish feed waste and feces), and the presence of oxytetracycline. We document a transformation ratio of EMB to DES of 0.16 to 4.4 % and show that the co-presence of oxytetracycline increases EMB calculated half-lives to values >6000 days for mud matrices. EMB incubated in high organic enrichment regimes was not observed to degrade at 4 degrees. Multivariate analyses show interactions between sediment conditions (matrix, temperature, organic matter [OM], oxytetracycline) influence EMB persistence and DES:EMB ratios. Ranges of EMB half-lives and information on metabolites can be used to anticipate potential effects on marine communities.

Teaching Trainees to be Effective Mentors: A Needs-Based Assessment in Radiation Oncology

PURPOSE/OBJECTIVE(S)

Mentorship plays a critical role in the training and career development of medical trainees. Teaching-the-teacher workshops for residents translate to higher long-term job satisfaction and improved patient communication skills. Further, near-peer mentorship has been associated with increased job satisfaction and patient care experience. Resident-as-mentors can add benefit to the mentorship networks of students, particularly in resource-limited environments, while benefiting residents' own mentorship relations and career satisfaction. We hypothesized that residents would desire to be a mentor, but would lack specific skills needed for effective mentoring of students in radiation oncology.

MATERIALS/METHODS

A multi-institution, cross-sectional study was conducted among residents in the Radiation Oncology Education Collaborative Study Group (ROECSG) Graduate Medical Education working group from 06/2022-10/2022. Participants completed the Mentorship Competency Assessment (MCA), a validated 26-item questionnaire, scored on a Likert scale from 0-7 (0: most unprepared with mentorship skill, 7: most prepared with mentorship skill). The primary endpoint was the average score in individual mentorship skills among participants. Kruskal-Wallis test assessed associations between total MCA score (range 0-182) and demographics.

RESULTS

A total of 36 of 39 participants (92% response rate) responded. A majority were male (58%), from a residency size >10 (75%), and P Gy-2/3 (52%). Most had no formal training in teaching (86%) or mentorship (89%). Many believed they would be a good mentor to students on a rotation (89%), but most felt they would benefit from a formal mentorship program (92%). From the MCA, the mentorship skills residents felt most unprepared for were: coordinating effectively with other mentors (3.4/7), helping mentees acquire resources (3.6/7), negotiating a path to professional independence with mentees (3.6/7), helping mentees network effectively (3.7/7), and working with mentees to set clear expectations of the mentoring relationship (3.9/7). The mentorship skills residents felt most prepared for were: acknowledging mentees' professional contributions (5.6/7), establishing a relationship based on trust (5.6/7), active listening (5.5/7), building mentees' confidence (4.9/7), and working effectively with mentees with personal backgrounds differing from one's own (4.8/7). Higher MCA scores were associated with former training in mentorship (p = 0.0143), and a trend for former training in teaching (p = 0.0525), but was not associated with sex (p = 0.5986), residency size (p = 0.1415), or P Gy-year (p = 0.9747).

CONCLUSION

Residents are interested in mentorship training and report unpreparedness in several important skills. Future work should focus on formal training and assessment of mentoring skills for residents.

Knowledge Based Planning Evolution: Multi-Criteria Optimization of Prostates. Is There Always a Better Model?

PURPOSE/OBJECTIVE(S)

The current paradigm of radiotherapy Knowledge Based Planning (KBP) utilizes dose volume relationships on previously treated plans and may be insensitive to clinician plan preferences. To improve KBP models, incorporation of plan quality metrics and optimization weightings can be achieved using Clinical Scoring Metrics (CSM) and Multi-Criteria Optimization (MCO) respectively. A combination of KBP, MCO and CSM may result in higher quality plan output with potential to improve all prospective clinical plans. This study assesses the benefit of MCO, using CSM, and its application in the evolution of the KBP model.

MATERIALS/METHODS

A retrospective Dose Volume Histogram (DVH) parameter review was undertaken for 40 intact prostate radiotherapy cases. Following analysis, these cases were used to develop the CSM system to reflect clinician preferences and departmental protocol. Hypofractionated plans containing simultaneous integrated boost (SIB) and urethral sparing were originally planned using a clinically approved KBP model (Model A). Model A was then refined using MCO, improving the 40 individual model plans to form Model B. A further 20 prostate patients, who were excluded from KBP development, were planned using both models to compare plan quality using the CSM system.

RESULTS

Using a single optimization, Model A resulted in a median plan score of 134.1 (92.4-151.5), compared to the median Model B score of 145.1 (114.5-175.1) out of a possible score of 200 points. A Wilcoxon rank sum test was conducted and found the model score difference was significant (p = 0.014). Organ At Risk (OAR) doses, including Rectum V30 Gy, were found to significantly (p = 0.019) decrease, with Model A resulting in a median of 22.1 Gy (9.3-39.0), compared to the Model B median of 16.3 Gy (6.8-35.7). PTV coverage metric V57 Gy, resulted in no significant differences (p = 0.47) with a median score of 98.4% (97.2% - 99.9%) and 98.4% (96.9% - 99.2%) for model A and B, respectively.

CONCLUSION

The application of MCO was used to influence and produce higher quality KBP models, as supported by a CSM system. OAR doses were found to significantly decrease, with no effect on target coverage. As a result, existing plan objectives were tightened through the utilization of KBP models, even with a single optimization resulting in higher scoring plans. The future development of this work may increase the efficiency of planning operations and allow the clinician to accurately anticipate planning goals for not only prostate, but all disease sites.

TEAMRO: TEAching Mentorship in Radiation Oncology, a Multicenter Prospective Phase 2 Intervention Study on Teaching Mentorship Skills to Residents Working with Medical Students

PURPOSE/OBJECTIVE(S)

While formal curriculum on resident teaching have been associated with improved career growth and sustained positive impact on patient care, mentorship skills are rarely taught in academic medicine. We hypothesized that a formalized resident mentorship curriculum coupled with a near-peer resident-medical student mentoring program would improve resident career growth.

MATERIALS/METHODS

A multi-institutional, prospective, phase 2 intervention study, approved by each participating center's institutional review board, was conducted from 4/2022-10/2022 among interested residents in the Radiation Oncology Education Collaborative Study Group Graduate Medical Education. Intervention included: 1) a 4-week mentorship curriculum (utilizing a Six Steps approach) composed of self-guided readings, didactic lecture, and 30-minute faculty check-in, and 2) a formalized 1:1 resident-medical student mentorship program during an existing radiation oncology sub-internship with weekly meetings. Resident participants completed the Mentorship Competency Assessment (MCA), a 26-item validated survey on mentorship skills in medicine scored from 0 (most unprepared) to 7 (most prepared) before and after the intervention. The primary endpoint was average change in MCA skill from pre- to post-intervention survey, with score ranges from -7 (a decrease in 7 points) to +7 (an increase of 7 points).

RESULTS

A total of 8 residents participated and all completed pre- and post-intervention surveys. Most residents were PGY-4/5 (75%), from programs with >10 residents (68%), and did not have prior training in teaching (88%) or mentorship (88%). Residents met students on average twice weekly (range 1-3) for an average of 2 hours a week (range 1-5). After the program, most residents felt confident in being a future mentor to students (100%), their overall well-being was positively impacted (63%), and their mentorship relationships were positively impacted (50%). All 26 mentorship skills increased on MCA after intervention (average +1.3/7 per skill). Skills that showed greatest improvement were helping mentees network effectively (+2.6/7), acquire resources (+2.1/7), negotiate a path to professional independence (+2.0/7), set career goals (+1.8/7), and balance work and personal life (+1.7/7). Skills that showed least improvement were establishing a relationship based on trust (+0.4/7), identifying and accommodating different communication styles (+0.6/7), providing constructive feedback (+0.7/7), and aligning mentor-mentee expectations (+0.8/7).

CONCLUSION

The formalized mentorship program improved mentorship skills among residents, translating to increased satisfaction in residents' own mentorship relations and overall well-being. Further studies are needed to assess the sustainability of these skills, as well as impact on career growth and satisfaction.

Metabolization of emamectin benzoate into desmethyl emamectin benzoate in spiked marine sediments

Emamectin benzoate (EMB) (4″deoxy- 4″-epi-methylaminoavermectin) is a pesticide developed to control pests on various crops, and in forestry. It is also used in salmon aquaculture to control sea lice infestations as an in-feed therapeutant. Little is known about EMB metabolites and potential associated toxicities in marine sediments. In this study, we used natural marine sediments (sand and mud) fortified at an EMB concentration of 60 ppb (wet weight). Results show an almost immediate transformation of EMB to Desmethyl EMB (DES) with no increased rates of metabolization when stored sediment samples were incubated for up to 16 h. The transformation ratio of EMB to DES represented between 0.16 and 0.39% of EMB; values are lower than what has been observed in fish tissue. Data suggest that DES is generated through both abiotic (tested after autoclaving marine sediments) and biological processes. Further work on freshly sampled marine sediments with EMB deposits, different organic regimes, and a detailed assessment of active bacterial communities are necessary to better evaluate the EMB to DES rate of transformation around aquaculture sites.

River Basin Export Reduction Optimization Support Tool; a tool to screen options for reducing nutrient loads while minimizing cost

Excess loading of nitrogen and phosphorus to river networks causes environmental harm, but reducing loads from large river basins is difficult and expensive. We develop a new tool, the River Basin Export Reduction Optimization Support Tool (RBEROST) to identify least-cost combinations of management practices that will reduce nutrient loading to target levels in downstream and mid-network waterbodies. We demonstrate the utility of the tool in a case study in the Upper Connecticut River basin in New England, USA. The total project cost of optimized lowest-cost plans ranged from $18.0 million to $41.0 million per year over 15 years depending on user specifications. Plans include both point source and non-point source management practices, and most costs are associated with urban stormwater practices. Adding a 2% margin of safety to loading targets improved estimated probability of success from 37.5% to 99%. The large spatial scale of RBEROST, and the consideration of both point and non-point source contributions of nutrients, makes it well suited as an initial screening tool in watershed planning.

P-580 Cumulative live birth rate of oocyte in-vitro maturation with a pre-maturation step in women with polycystic ovary syndrome or high antral follicle count

Study question

What is the cumulative live birth rate (CLBR) at 24 months of women undergoing oocyte in vitro maturation (IVM) a with pre-maturation step (CAPA-IVM)?

Summary answer

The CLBR at 24 months with CAPA-IVM was 38.2%.

What is known already

IVM with a pre-maturation step, known as capacitation IVM (CAPA-IVM) improves the competence of oocytes matured in-vitro by sustaining meiotic arrest to allow the synchronization of cytoplasmic and genetic maturation of the oocytes. Results from a randomized controlled trial showed that CAPA-IVM resulted in a live birth rate after the first transfer of 35.2% which was non-inferior to IVF. There is a lack of data on cumulative live birth following CAPA-IVM.

Study design, size, duration

A multi-center, retrospective study, performed at IVFMD, My Duc Hospital and IVFMD Phu Nhuan, My Duc Phu Nhuan Hospital from 1 January 2017 to 31 December 2019.

Participants/materials, setting, methods

All women with polycystic ovary syndrome (PCOS) or high antral follicle count (AFC) treated with a CAPA-IVM cycle were recruited to the study. All embryos were frozen at day 3. Cumulative live birth was difined as at least one live birth resulting from initiated CAPA-IVM cycle. If the women did not return for embryo transfer, outcomes were followed up until 24 months from aspiration day. Logistic regression was performed to assess which factors predicted CLBR.

Main results and the role of chance

Between 1 January 2019 and 31 December 2019, there were 374 eligible women included in the study, among them, 368 patients had embryos for transfer (98.4%) and six patients had no embryo for transfer (1.6%). A total of 496 frozen embryo transfer (FET) cycles from 368 patients were performed. Mean age and body max index (BMI) were 29.5±3.21 years and 22.3±3.09, respectively. The maturation rate was 63.2%. The median number of embryos was 4.0 [2.00; 6.00]. The cumulative clinical pregnancy rate was 60.4%, cumulative ongoing pregnancy rate was 51.6%. At 24 months after starting the treatment, the CLBR of CAPA-IVM was 38.2%. Multivariate analysis showed that patient age and number of metaphase II oocytes were the predictive factors for cumulative live birth after CAPA-IVM.

Limitations, reasons for caution

The study limitation derives from its retrospective nature. The generalizability of the study may be limited due to the single ethnicity group.

Wider implications of the findings

In patients with PCOS or high AFC, CAPA-IVM was viable and resulted in acceptable CLBR. CAPA-IVM may be the first-line treatment for women with PCOS or high AFC requiring assisted reproduction.

Trial registration number

not applicable

O-223 Latest development of IVM in assisted reproduction

Latest development of IVM in assisted reproduction

In vitro maturation (IVM) is an assisted reproductive technology involving collection of immature cumulus-oocyte complexes at the prophase I stage, which are then matured to the metaphase II stage in vitro. IVM has several advantages over IVF, including negligible risk of ovarian hyperstimulation syndrome, lower medication costs, and patient convenience.

Given that IVM can be done within a relatively short time frame without the need for ovarian stimulation, it is particularly useful for fertility preservation in patients with cancer who are unable to delay chemotherapy, or in women with breast cancer for whom exposure to elevated estradiol concentrations may accelerate their disease. The European Society of Human Reproduction and Embryology (ESHRE) Guideline on Female Fertility Preservation published in 2020 suggested IVM as a fertility preservation technique.

The Practice Committees of ASRM in 2021 published the document that presented an overview of published evidence supporting the conclusion that IVM should no longer be considered an experimental technique. The potential for wider clinical application of IVM was suggested. Patient populations particularly suited to the use of IVM include women with polycystic ovaries, have higher risk of ovarian hyperstimulation syndrome, and those requiring fertility preservation.

During the last two decades, IVM has been utilized for patients with PCOS to reduce the health risks associated with ovarian hyperstimulation syndrome, for fertility preservation, or just as an alternative, more user-friendly approach to ART.

The effectiveness of IVM relies on successful synchronization of meiotic and cytoplasmic maturation of oocytes. Efforts to improve the efficacy of IVM have included the use of new IVM culture systems, aimed at enhancing the competence of IVM oocytes. Recently, the use of oocyte prematuration (or pre-IVM) culture systems to prevent spontaneous in vitro maturation processes and maintain cumulus-oocyte gap junctional communication have been described in humans.

Over the last five years, a new biphasic IVM culture system has been developed to improve the efficacy of IVM. Recent promising data from this new IVM culture system, called capacitation (CAPA) IVM, showed promising results. CAPA-IVM involves successfully maturing oocytes from small 2–8 mm follicles with no hCG injected prior to oocyte retrieval. Recently, a large RCT compared the efficacy of CAPA IVM and conventional IVF/ICSI in women with PCO showed that CAPA (biphasic) IVM was non-inferior to IVF in term of live birth rate after the first embryo transfer.

One of the concerns regarding IVM is the health of babies after utilization of this procedure. Based on currently available data, IVM appears to be safe from a neonatal health and childhood development perspective.

There is still room for further development of more efficient IVM protocols (89). Recent knowledge about oocyte physiology and development can be translated into clinical practice to improve the efficacy of these protocols.

There are several reasons why all major modern ART centers should have IVM facilities and protocols available. These include the likelihood of wider application of IVM in the future, the requirement to manage indications where IVM is the only option (e.g. fertility preservation, GROS), the increasing need for more patient-friendly ART treatment, and the fact that IVM protocols are improving thanks to advances in knowledge on human follicular and oocyte development.

P–247 Application of deep learning for automated measurement of key morphological features of human zygotes for IVF

Study question

Can deep learning (DL) algorithms trained on time-lapse videos be used to detect and track the size and gender of pronuclei in developing human zygotes?

Summary answer

Our DL algorithm not only outperforms state-of-the-art models in detecting the pronuclei but can also accurately identify and track its gender and size over time.

What is known already

Recent researches have explored the use of DL to extract key morphological features of human embryos. Existing studies, however, focus either on blastocysts’ morphological measurements (Au et al. 2020) or on embryos’ general developmental stages classification (Gingold et al. 2018, Liu et al. 2019, Lau et al. 2019). So far, only one paper attempted to evaluate zygotes’ morphological components but stopped short of identifying the existence and location of their pronuclei (Leahy et al. 2020). We address this research gap by training a DL model that can detect, classify the gender, and quantify the size of zygotes’ pronuclei over time.

Study design, size, duration

A retrospective analysis using 91 fertilized oocytes from infertile patients undergoing IVF or ICSI treatment at Hanabusa Women’s Clinic between January 2011 and August 2019 was conducted. Each embryo was time-lapse monitored using Vitrolife which records an image every 15 minutes at 7 focal planes. For our study, we used videos of the first 1–2 days of the embryo from its 3 central focal planes, corresponding to 70–150 images per focal plane.

Participants/materials, setting, methods

All 273 timelapse videos were split into 30,387 grayscale still images at a 15-minute interval. Each image was checked and annotated by experienced embryologists where every pixel of the image was classified into 3 categories: male pronuclei, female pronuclei, and others. Images were converted into grayscale, resized into 500x500 pixels, and then fed into a neural network with the Mask R-CNN architecture and a ResNet101 backbone to produce a pronuclei instance segmentation model.

Main results and the role of chance

The 91 embryos were split into training (∼70% or 63 embryos) and validation (∼30% or 28 embryos). Our pronuclei model takes as input a single image and outputs a bounding box, mask, category, confidence score, and size measured in terms of pixel for each detected candidate. For prediction, we run the model on the 3 middle focal planes and merge candidates by using the one with the highest confidence score. We used the mean-average precision (mAP) score to evaluate our model’s ability to detect pronuclei and used the mean absolute percentage error (MAPE) between the actual size (as annotated by the embryologist) and the predicted one to check the model’s performance in tracking the pronuclei’s size.

The mAP for detecting pronuclei, regardless of its gender, achieved by our model was 0.698, higher than the 0.680 value reported in the Leahy et al. paper (2020). Breakdown by gender, our model’s mAP for male and female pronuclei are 0.734 and 0.661 respectively.

The overall MAPE for tracking pronuclei’s size is 21.8%. Breakdown by gender, our model’s MAPE for male and female pronuclei are 19.4% and 24.3% respectively.

Limitations, reasons for caution

Samples were collected from one clinic with videos recorded from one time-lapse system which can limit our results’ reproducibility. The accuracy of our DL model is also limited by the small number of embryos that we used.

Wider implications of the findings: Even with a limited training dataset, our results indicate that we can accurately detect and track the gender and the size of zygotes’ pronuclei using time-lapse videos. In future models, we will increase our training dataset as well as include other time-lapse systems to improve our models’ accuracy and reproducibility.

Trial registration number

Not applicable

Report on G4-Med, a Geant4 benchmarking system for medical physics applications developed by the Geant4 Medical Simulation Benchmarking Group

BACKGROUND

Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, micro- and nanodosimetry, imaging, radiation protection, and nuclear medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing.

AIMS

To respond to these needs, we developed G4-Med, a benchmarking and regression testing system of Geant4 for medical physics.

MATERIALS AND METHODS

G4-Med currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the prebuilt Geant4 physics lists are tested. The tests included in G4-Med are executed on the CERN computing infrastructure via the use of the geant-val web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes.

RESULTS

This paper describes the tests included in G4-Med and shows the results derived from the benchmarking of Geant4 10.5 against reference data.

DISCUSSION

Our results indicate that the Geant4 electromagnetic physics constructor G4EmStandardPhysics_option4 gives a good agreement with the reference data for all the tests. The QGSP_BIC_HP physics list provided an overall adequate description of the physics involved in hadron therapy, including proton and carbon ion therapy. New tests should be included in the next stage of the project to extend the benchmarking to other physical quantities and application scenarios of interest for medical physics.

CONCLUSION

The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.

Proceedings from the OMS Resurgence Conference for resuming clinical practice after COVID-19 in the USA

The COVID-19 pandemic has altered and reshaped the delivery of oral and maxillofacial surgery (OMS) over the past few months. As the USA gradually lifts restrictions and re-opens, surgeons must adjust accordingly. Therefore, the OMS Resurgence Conference: Safely Resuming Practice with a New Normal was organized for 11 May 2020 to gather and disseminate expert opinions and recommendations for OMSs to thoughtfully resume work with efficiency and safety. This manuscript offers a summary of the highlights from the conference discussion.

Pressure Tensor Elements Breaking the Frozen-In Law During Reconnection in Earth's Magnetotail

Aided by fully kinetic simulations, spacecraft observations of magnetic reconnection in Earth's magnetotail are analyzed. The structure of the electron diffusion region is in quantitative agreement with the numerical model. Of special interest, the spacecraft data reveal how reconnection is mediated by off-diagonal stress in the electron pressure tensor breaking the frozen-in law of the electron fluid.

Observations of Multiple Nuclear Reaction Histories and Fuel-Ion Species Dynamics in Shock-Driven Inertial Confinement Fusion Implosions

Fuel-ion species dynamics in hydrodynamiclike shock-driven DT^{3}He-filled inertial confinement fusion implosion is quantitatively assessed for the first time using simultaneously measured D^{3}He and DT reaction histories. These reaction histories are measured with the particle x-ray temporal diagnostic, which captures the relative timing between different nuclear burns with unprecedented precision (∼10  ps). The observed 50±10  ps earlier D^{3}He reaction history timing (relative to DT) cannot be explained by average-ion hydrodynamic simulations and is attributed to fuel-ion species separation between the D, T, and ^{3}He ions during shock convergence and rebound. At the onset of the shock burn, inferred ^{3}He/T fuel ratio in the burn region using the measured reaction histories is much higher as compared to the initial gas-filled ratio. As T and ^{3}He have the same mass but different charge, these results indicate that the charge-to-mass ratio plays an important role in driving fuel-ion species separation during strong shock propagation even for these hydrodynamiclike plasmas.

Electron Bulk Acceleration and Thermalization at Earth's Quasiperpendicular Bow Shock

Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

Orientation and Stability of Asymmetric Magnetic Reconnection X Line

The orientation and stability of the reconnection x line in asymmetric geometry is studied using three-dimensional (3-D) particle-in-cell simulations. We initiate reconnection at the center of a large simulation domain to minimize the boundary effect. The resulting x line has sufficient freedom to develop along an optimal orientation, and it remains laminar. Companion 2-D simulations indicate that this x line orientation maximizes the reconnection rate. The divergence of the nongyrotropic pressure tensor breaks the frozen-in condition, consistent with its 2-D counterpart. We then design 3-D simulations with one dimension being short to fix the x line orientation but long enough to allow the growth of the fastest growing oblique tearing modes. This numerical experiment suggests that reconnection tends to radiate secondary oblique tearing modes if it is externally (globally) forced to proceed along an orientation not favored by the local physics. The development of oblique structure easily leads to turbulence inside small periodic systems.

Cellular Plasticity-Targeted Therapy in Head and Neck Cancers

Head and neck cancer is one of the most frequent human malignancies worldwide, with a high rate of recurrence and metastasis. Head and neck squamous cell carcinoma (HNSCC) is cellularly and molecularly heterogeneous, with subsets of undifferentiated cancer cells exhibiting stem cell-like properties, called cancer stem cells (CSCs). Epithelial-mesenchymal transition, gene mutation, and epigenetic modification are associated with the formation of cellular plasticity of tumor cells in HNSCC, contributing to the acquisition of invasive, recurrent, and metastatic properties and therapeutic resistance. Tumor microenvironment (TME) plays a supportive role in the initiation, progression, and metastasis of head and neck cancer. Stromal fibroblasts, vasculature, immune cells, cytokines, and hypoxia constitute the main components of TME in HNSCC, which contributes not only to the acquisition of CSC properties but also to the recurrence and therapeutic resistance of the malignancies. In this review, we discuss the potential mechanisms underlying the development of cellular plasticity, especially the emergence of CSCs, in HNSCC. We also highlight recent studies implicating the complex interplays among TME components, plastic CSCs, tumorigenesis, recurrence, and therapeutic resistance of HNSCC. Finally, we summarize the treatment modalities of HNSCC and reinforce the novel concept of therapeutic targeting CSCs in HNSCC.

Spacecraft Observations of Oblique Electron Beams Breaking the Frozen-In Law During Asymmetric Reconnection

Fully kinetic simulations of asymmetric magnetic reconnection reveal the presence of magnetic-field-aligned beams of electrons flowing toward the topological magnetic x line. Within the ∼6d_{e} electron-diffusion region, the beams become oblique to the local magnetic field, providing a unique signature of the electron-diffusion region where the electron frozen-in law is broken. The numerical predictions are confirmed by in situ Magnetospheric Multiscale spacecraft observations during asymmetric reconnection at Earth's dayside magnetopause.

[Study of diagnostic value of natremia in a cohort of patients with hypercalcemia]

INTRODUCTION

Hypercalcemia is a common pathological condition in clinical practice. The two most common causes are primary hyperparathyroidism and cancer. SIADH is often encountered in cancer cases and is the most common cause of hyponatremia. The aim of this study is to evaluate serum sodium levels in a cohort of patients with hypercalcemia and consider its predictive value in determining the origin of this hypercalcemia.

MATERIALS AND METHODS

We performed a retrospective study on a series of 15.284 blood tests among adult patients with hypercalcemia. After selection, the study population had 151 patients. We studied mainly serum sodium and etiology of hypercalcemia in our population.

RESULTS

We observed a statistically significant association between the presence of hyponatremia and the neoplastic etiology of hypercalcemia. This association persisted after exclusion of patients under treatment with loop diuretics. Conversely, there was no association between hypernatremia and cancer-related hypercalcemia. Among 151 patients with hypercalcemia, 16 presented hyponatremia and 7 with hypernatremia. SIADH was the main cause of hyponatremia. We performed univariate and multivariate logistic regression showing the association between the presence of cancer and the presence of hyponatremia.

CONCLUSION

Our study shows that there is an association between the presence of hyponatremia and neoplastic origin of hypercalcemia. Besides, the association described between hyponatremia and cancer is not faulted by the presence of hypercalcemia, a potential cause of acquired nephrogenic diabetes insipidus.