MRI biomarker of muscle composition is associated with severity of pelvic organ prolapse.

BACKGROUND: The pathophysiology of pelvic organ prolapse is largely unknown. We hypothesized that reduced muscle mass on magnetic resonance defecography (MRD) is associated with increased pelvic floor laxity. The aim of this study was to compare the psoas and puborectalis muscle mass composition and cross-sectional area among patients with or without pelvic laxity. METHODS: An observational retrospective study was conducted on women > age 18 years old who had undergone MRD for pelvic floor complaints from January 2020 to December 2020 at Stanford Pelvic Health Center. Pelvic floor laxity, pelvic organ descent, and rectal prolapse were characterized by standard measurements on MRD and compared to the psoas (L4 level) and puborectalis muscle index (cross-sectional area adjusted by height) and relative fat fraction, quantified by utilizing a 2-point Dixon technique. Regression analysis was used to quantify the association between muscle characteristics and pelvic organ measurements. RESULTS: The psoas fat fraction was significantly elevated in patients with abnormally increased resting and strain H and M lines (p < 0.05) and increased with rising grades of Oxford rectal prolapse (p = 0.0001), uterovaginal descent (p = 0.001) and bladder descent (p = 0.0005). In multivariate regression analysis, adjusted for age and body mass index, the psoas fat fraction (not muscle index) was an independent risk factor for abnormal strain H and M line; odds ratio (95% confidence interval) of 17.8 (2-155.4) and 18.5 (1.3-258.3) respectively, and rising Oxford grade of rectal prolapse 153.9 (4.4-5383) and bladder descent 12.4 (1.5-106). Puborectalis fat fraction was increased by rising grades of Oxford rectal prolapse (p = 0.0002). CONCLUSIONS: Severity of pelvic organ prolapse appears to be associated with increasing psoas muscle fat fraction, a biomarker for reduced skeletal muscle mass. Future prospective research is needed to determine if sarcopenia may predict postsurgical outcomes after pelvic organ prolapse repair.

Potential role of fibroblast growth factor 21 in the deterioration of bone quality in impaired glucose tolerance.

PURPOSE: Findings on trabecular bone score (TBS), an index of bone quality, have been reported in prediabetes defined by impaired fasting glucose or HbA1c. Here, we assessed the bone mineral density (BMD) and TBS in prediabetes individuals with impaired glucose tolerance (IGT), and investigated the association of these bone parameters with serum levels of fibroblast growth factor 21 (FGF21), a hormone implicated in bone metabolism and with higher levels in IGT. METHODS: Chinese postmenopausal women aged 55-80 years, without diabetes, were recruited from the Hong Kong Cardiovascular Risk Factor Prevalence Study in 2016-2018. Normal glucose tolerance (NGT) was defined by fasting glucose < 5.6 mmol/L and 2-h plasma glucose (2hG) < 7.8 mmol/L, and IGT by 2hG 7.8-11 mmol/L. Serum levels of FGF21 and other bone metabolism regulators were measured. Insulin sensitivity was assessed by the Matsuda index. Independent determinants of TBS were evaluated using multivariable stepwise linear regression. RESULTS: 173 individuals with NGT and 73 with IGT were included. TBS was lower in those with IGT compared to those with NGT, while BMD was comparable. Individuals with IGT had significantly higher serum FGF21 levels, which in turn showed an independent inverse relationship with TBS, attenuated after inclusion of the Matsuda index. Serum FGF21 levels, however, did not correlate with BMD. CONCLUSION: Among Chinese postmenopausal women, bone quality was worse in IGT, despite comparable bone density. FGF21 levels showed a significant independent inverse relationship with TBS, partly attributed to insulin resistance. Whether FGF21 contributes to the impaired bone quality in IGT remains speculative.

Interobserver variability in the classification of childhood maculopapular cutaneous mastocytosis.

BACKGROUND: Maculopapular cutaneous mastocytosis (MPCM) in children is classified in two variants: (i) monomorphic variant, presenting with the small macules or papules typically seen in adult patients; and (ii) polymorphic variant with larger lesions of variable size and shape, typically seen in children. The definition of polymorphic and monomorphic variants is mostly intuitive, and a validation of this classification has not been done. OBJECTIVE: To study interobserver variability in the classification of MPCM in two groups of observers: mastocytosis experts and general dermatologists. MATERIALS AND METHODS: Nineteen cases of childhood MPCM were shown blindly, for classification as monomorphic or polymorphic type, to 10 independent observers (eight dermatologists, one allergist and one haematologist) from Europe and North America with a vast experience in the management of paediatric mastocytosis. Also, the same cases were shown on a screen to 129 general dermatologists attending a meeting; their votes were registered by remote controls. The interobserver variability kappa coefficient (with 95% confidence interval) was calculated to measure the reliability of the correlation. RESULTS: The value of kappa interobserver variability coefficient for the group of 10 experts (95% confidence interval) was 0.39 (0.18-0.63), which is considered as 'fair'. The value of kappa interobserver variability coefficient for the group of 129 general dermatologists (95% confidence interval) was 0.17 (0.06-0.39), which is considered as 'slight'. A complete agreement of all 10 experts was achieved in only four of 19 cases (21.1%) The most voted choice was concordant between the two groups in only 11 of the 19 cases. CONCLUSIONS: We failed to validate the classification system of childhood MPCM in monomorphic and polymorphic types. While the rate of agreement was low for mastocytosis experts, it was nearly the agreement expected by chance in general dermatologists.

Cytoreductive nephrectomy in metastatic renal cell carcinoma: outcome of patients treated with a multidisciplinary, algorithm-driven approach.

PURPOSE: Metastatic renal cell carcinoma (mRCC) represents a significant and rising burden of disease, with rapidly evolving treatment modalities. The role of cytoreductive nephrectomy (CN) is controversial in this setting. As such, London Cancer has pursued a multidisciplinary team (MDT) approach when assessing suitability for surgery. METHODS: A retrospective analysis of treatment-naive synchronous mRCC patients, managed via a renal-specialist MDT, was conducted between January 2015 and December 2018. An MDT selection algorithm for CN-using the International Metastatic Renal Cell Carcinoma Database Consortium score (IMDC), performance status and metastatic disease burden-was developed. RESULTS: 87 treatment-naive synchronous mRCC patients received either CN (n = 18), Systemic therapy (ST) alone (n = 43) or Best supportive care (BSC) (n = 26). Progression free survival (PFS) and overall survival (OS) were assessed. 51% and 39% were IMDC intermediate and poor risk. Median PFS was 28.6 months and 4.5 months in the CN group and ST alone group, respectively, Hazard Ratio for death was 3.63 [(95% CI 1.68-7.83) p < 0.05]. OS remains immature for the CN group, but a median OS of 12.8 months was observed in the ST group and 5.0 months for BSC. 1-year OS rate for CN, ST and BSC groups was 77.8%, 55.8% and 23.10%, respectively. CONCLUSION: These findings describe outcomes of an unselected series of patients treated via an MDT-driven, protocolised treatment pathway. MDT pathway-based decision making may improve patient selection for CN. Further research is needed to evaluate the role of CN amongst a growing landscape of treatment strategies, including immune checkpoint inhibitors and combination therapies. Multi-disciplinary team, pathway-based treatment strategy may improve patient selection for cytoreductive nephrectomy in patients with metastatic renal cell carcinoma.

A 5-year retrospective study of melioidosis cases treated in a district specialist hospital.

INTRODUCTION: Melioidosis is caused by Burkholderia pseudomallei, a gram-negative aerobic bacillus, found in the soil and surface water. Treating melioidosis has been a challenge in district hospitals due to high usage of broad spectrum antibiotics and prolonged hospitalisation. This study is to review the patients' demography, clinical presentations and microbiological data. METHODS: A 5-year retrospective study was carried out on patients admitted with culture positive for melioidosis from year 2013 to 2017 in Hospital Teluk Intan, Perak. RESULTS: There were a total of 46 confirmed cases of melioidosis. Majority of the patients were working in the agricultural and farming (28.6%), and factories (25.7%). Thirty-one patients had diabetes mellitus (71.1%). Presentations of patients with melioidosis included pneumonia (54.3%), skin and soft tissue infection (19.6%), deep abscesses (15.2%) and bone and joint infections (13%). An average of 5.8 days was needed to confirm the diagnosis of melioidosis via positive culture. However, only 39.4% of these patients were started on ceftazidime or carbapenem as the empirical therapy. The intensive care unit (ICU) admission rate for melioidosis was 46% and the mortality rate was 52%. Our microbial cultures showed good sensitivity towards cotrimoxazole (97.1%), ceftazidime (100%) and carbapenem (100%). CONCLUSION: Melioidosis carries high mortality rate, especially with lung involvement and bacteremia. Physicians should have high clinical suspicion for melioidosis cases to give appropriate antimelioidosis therapy early.

High-grade cervical intraepithelial neoplasia in human papillomavirus self-sampling of screening non-attenders.

BACKGROUND: Self-sampling for human papillomavirus (HPV) offered to women who do not participate in cervical cancer screening is an increasingly popular method to increase screening coverage. The rationale behind self-sampling is that unscreened women harbour a high proportion of undetected precancer lesions. Here, we compare the cervical intraepithelial neoplasia grade 2 or worse (⩾CIN2) detection rate between non-attenders who participated in self-sampling and women attending routine screening. METHODS: A total of 23 632 women who were qualified as non-attenders in the Copenhagen Region were invited for HPV-based self-sampling. Of these, 4824 women returned a self-sample, and HPV-positive women were referred for cytology and HPV co-testing as follow-up. The entire cohort and a reference cohort (3347 routinely screened women) were followed for histopathology confirmed ⩾CIN2. Odds ratio (OR) and the relative positive predictive value of ⩾CIN2 detection between the two populations were estimated. RESULTS: Women participating in self-sampling had a higher ⩾CIN2 detection than women undergoing routine cytology-based screening (OR=1.83, 95% CI: 1.21-2.77) and a similar detection as routinely screened women tested with cytology and HPV testing (OR=1.03, 95% CI: 0.75-1.40). The positive predictive value for ⩾CIN2 was higher in screening non-attenders than in routinely HPV- and cytology-screened screened women (36.5% vs 25.6%, respectively). CONCLUSIONS: Self-sampling offered to non-attenders showed higher detection rates for ⩾CIN2 than routine cytology-based screening, and similar detection rates as HPV and cytology co-testing. This reinforces the importance of self-sampling for screening non-attenders in organised cervical cancer screening.

Acceptability of high-resolution anoscopy for anal cancer screening in HIV-infected patients.

OBJECTIVES: HIV-infected individuals are at increased risk of anal cancer. Screening for anal cancer precursors using high-resolution anoscopy (HRA) may be clinically beneficial. In this study, we examined patient tolerability of this procedure. METHODS: The acceptability of HRA was evaluated among HIV-infected patients who completed a first-time HRA between July 2008 and December 2013 at Kaiser Permanente Northern California. We reviewed electronic medical records to identify lack of HRA acceptability, which was defined as receipt of HRA with sedation, dispensation of opioid analgaesia, and/or an urgent care visit following HRA, and to evaluate factors associated with patients not returning for a recommended repeat HRA (proxy for HRA acceptability). HRA acceptability was also assessed via a survey mailed to patients who completed HRA between January 2014 and August 2014. Logistic regression was used to model lack of acceptability of initial HRA and likelihood of not returning for a repeat HRA. RESULTS: Of 1857 HIV-infected patients, 94 were prescribed opioids and one had an urgent care visit. Lack of HRA acceptability was more likely in patients with pre-existing anal conditions [e.g. warts or fissure; adjusted odds ratio (aOR) 4.02; 95% confidence interval (CI) 2.4-6.7], those who had ever smoked (aOR 1.6; 95% CI 1.0-2.5) and women (aOR 5.3; 95% CI 1.6-17.5). Fifty per cent of patients returned for a repeat HRA, with younger patients less likely to return (per 10-year age interval, aOR 0.8; 95% CI 0.7-0.9). Of 48 survey respondents, 91.7% reported acceptable pain levels and all reported willingness to return for a repeat HRA. CONCLUSIONS: HRA was generally well tolerated and may be an acceptable screening approach for patients at high risk of anal cancer.

Observation of an Unusual Upward-Going Cosmic-Ray-like Event in the Third Flight of ANITA.

We report on an upward traveling, radio-detected cosmic-ray-like impulsive event with characteristics closely matching an extensive air shower. This event, observed in the third flight of the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload, is consistent with a similar event reported in a previous flight. These events could be produced by the atmospheric decay of an upward-propagating τ lepton produced by a ν_{τ} interaction, although their relatively steep arrival angles create tension with the standard model neutrino cross section. Each of the two events have a posteriori background estimates of ≲10^{-2} events. If these are generated by τ-lepton decay, then either the charged-current ν_{τ} cross section is suppressed at EeV energies, or the events arise at moments when the peak flux of a transient neutrino source was much larger than the typical expected cosmogenic background neutrinos.

Principles of haemophilia care: The Asia-Pacific perspective.

Optimal haemophilia care is best established and implemented through a well-coordinated plan guided by clearly defined principles and priorities. A document which enunciates those details is therefore important. A successful example of this approach is the definition of principles of haemophilia care (PHC) outlined by the European Association for Haemophilia and Associated Disorders (EAHAD) and also the World Federation of Hemophilia. A similar document applicable to the Asia-Pacific region must take into account not only the highly varied healthcare systems but also the tremendous socio-economic and cultural diversities which impact provision of such care. The Asia-Pacific Haemophilia Working Group (APHWG), representing the countries in this region, has prepared this perspective of the PHC. While endorsing the overall framework outlined by EAHAD, this APHWG document emphasizes regional priorities on education and training of healthcare personnel in the diagnosis and management of hereditary bleeding disorders. Central coordinating agencies with wide stakeholder input, networks of haemophilia treatment centres and national registries as well as robust processes for procurement and distribution of safe and effective clotting factor concentrates (CFCs), implementation of prophylaxis programmes and management of patients with inhibitors should also be developed. The implementation of these strategies should lead to establishment of good comprehensive care programmes. This document should also be an advocacy tool to lobby for improved care for people with haemophilia (PWH) in the region. We urge national healthcare policy makers to consider these principles and initiate strong and decisive action to reach these goals.

Outcome of day treatment for older adults with affective disorders: An observational pre-post design of two transdiagnostic approaches.

OBJECTIVE: First, to evaluate the outcome of 2 transdiagnostic day treatment programs. A 20-week psychotherapeutic day treatment (PDT) and an activating day treatment (ADT) program delivered in blocks of 4 weeks with a maximum of 24 weeks with respect to depression, anxiety, and hypochondriasis. Second, to explore the impact of cognitive impairment and personality pathology on treatment outcome. METHODS: The course of depression (Inventory of Depressive Symptoms), anxiety (Geriatric Anxiety Inventory), and hypochondriasis (Whitley Index) were evaluated by linear mixed models adjusted for age, sex, level of education, and alcohol usage among 49 patients (mean age 65 years, 67% females) receiving PDT and among 61 patients (mean age 67.1, 61% females) receiving ADT. Pre-post effect-sizes were expressed as Cohen's d. Subsequently, cognitive impairment (no, suspected, established) and personality pathology (DSM-IV criteria as well as the Big Five personality traits) were examined as potential moderators of treatment outcome. RESULTS: Among patients receiving PDT, large improvements were found for depression (d = 1.1) and anxiety (d = 1.2) but not for hypochondriasis (d = 0.0). Patients receiving ADT showed moderate treatment effects for depression (d = 0.6), anxiety (d = 0.6), as well as hypochondriasis (d = 0.6). Personality pathology moderates treatment outcome of neither PDT nor ADT. Cognitive impairment negatively interfered with the course of depressive symptoms among patients receiving PDT. CONCLUSIONS: Transdiagnostic day treatment is promising for older adults with affective disorders with high feasibility.

Does intranasal dexmedetomidine provide adequate plasma concentrations for sedation in children: a pharmacokinetic study.

BACKGROUND: Atomised intranasal dexmedetomidine administration is an attractive option when sedation is required for paediatric diagnostic procedures, as vascular access is not required. The risk of haemodynamic instability caused by dexmedetomidine necessitates better understanding of its pharmacokinetics in young children. To date, intranasal dexmedetomidine pharmacokinetics has only been studied in adults. METHODS: Eighteen paediatric patients received dexmedetomidine 1 or 2 µg kg-1 intranasally or 1 µg kg-1 i.v. Plasma concentrations were determined by liquid chromatography/mass spectrometry. Non-compartmental analysis provided estimates of Cmax and Tmax. Volume of distribution, clearance, and bioavailability were estimated by simultaneous population PK analysis of data after intranasal and i.v. administration. Dexmedetomidine plasma concentration-time profiles were evaluated by simulation for intranasal and i.v. administration. RESULTS: An average peak plasma concentration of 199 pg ml-1 was achieved 46 min after 1 µg kg-1 dosing and 355 pg ml-1 was achieved 47 min after 2 µg kg-1 dosing. A two-compartment pharmacokinetic model, with allometrically scaled parameters, adequately described the data. Typical bioavailability was 83.8% (95% confidence interval 69.5-98.1%). CONCLUSION: Mean arterial plasma concentrations of dexmedetomidine in infants and toddlers approached 100 pg ml-1, the low end reported for sedative efficacy, within 20 min of an atomised intranasal administration of 1 µg kg-1. Doubling the dose to 2 µg kg-1 reached this plasma concentration within 10 min and achieved almost twice the peak concentration. Peak plasma concentrations with both doses were reached within 47 min of intranasal administration, with an overall bioavailability of 84%.

Diagnostic criteria for temporomandibular disorders: Diagnostic accuracy for general dentistry procedure without mandatory commands regarding myalgia, arthralgia and headache attributed to temporomandibular disorder.

The clinical examination in diagnostic criteria for temporomandibular disorders (DC/TMD) is a strict procedure and comprises mandatory commands. However, learning and using these mandatory commands in general practice have proven to be difficult and their use of DC/TMD is minimal. To investigate whether reliability on a diagnostic level for DC/TMD diagnoses differs between examiners using the mandatory commands or not. Six examiners were divided into two groups: one using the mandatory commands in DC/TMD for the clinical examination and one who did not use the mandatory commands. A reliability assessment was performed twice, one occasion for each group of examiners. The assessment was performed according to the guidelines from the International Network for Orofacial Pain and Related Disorders Methodology. Each group of examiners thereby examined 16 subjects (11 TMD patients and 5 healthy individuals) each, and the diagnostic agreement (reliability) as compared to diagnoses derived by a reference standard examiner was calculated with Cohen' s kappa coefficient. The DC/TMD diagnoses myalgia, arthralgia and headache attributed to TMD were included in the reliability assessment. There was no significant difference regarding diagnostic agreement reliability between the examiners using or not using the mandatory DC/TMD commands. This study indicates that not using the mandatory commands in DC/TMD in general practice does not impair the diagnostic reliability regarding the diagnoses myalgia, arthralgia and headache attributed to TMD compared to including the commands.

Prevalence of Human Papillomavirus in Self-Taken Samples from Screening Nonattenders.

The Copenhagen Self-Sampling Initiative (CSi) has shown how human papillomavirus (HPV)-based self-sampling can be used to increase screening participation among 23,632 nonattenders in the Capital Region of Denmark. In this study, we describe HPV prevalence and genotype frequency in 4,824 self-samples as determined by three HPV assays (the CLART, Onclarity, and Hybrid Capture 2 [HC2] assays) and compare the results with those for physician-taken follow-up samples. The HPV self-sample findings were also compared to the findings for a reference population of 3,347 routinely screened women from the Horizon study, which had been undertaken in the same screening laboratory. Nonattenders had an HPV prevalence of 11.3% as determined by the CLART assay, which was lower than that for women from the Horizon study (18.5%). One-third of the CSi women who tested HPV positive by self-sampling tested HPV negative on the physician-taken follow-up sample. The CLART and Onclarity assays agreed on 64% (95% confidence interval [CI], 60 to 68%) of the HPV-positive self-taken samples. When the HC2 assay results were added into a three-way comparison, the level of agreement decreased to 27% (95% CI, 24 to 29%). Our findings suggest that further validation of HPV assays on self-taken samples is needed for optimal HPV detection and correct clinical management of HPV-positive women.

Episodic replacement of clotting factor concentrates does not prevent bleeding or musculoskeletal damage - the MUSFIH study.

PATIENTS AND METHODS: A longitudinal study was carried out in 255 children from 10 centres in nine developing countries over 5 years to assess the musculoskeletal outcome of children on episodic factor replacement. Outcome was documented by assessment of the annual joint bleeding rate (AJBR), WFH clinical and Pettersson radiological joint scores as well as the FISH score for activities. Of the 203 patients for whom data was available at the end of 5 years, 164 who had received only episodic treatment are included in this report. RESULTS: The median age at the beginning of the study was 10 years (IQR 7-12). The median clotting factor concentrate (CFC) usage was 662 IU kg-1 year-1 (IQ range: 280-1437). The median AJBR was 10 (IQ range: 5-17). The median AJBR was higher in the older children with the median being 5 for the 5 year old child, while it was 9 for the 10 year old and 11 for children older than 15. Given the episodic nature of the replacement therapy, those with a higher AJBR used significantly greater annual CFC doses (P < 0.001); The median change in WFH clinical score and Pettersson radiological score over the 5 years was 0.4/year for each, while the FISH deteriorated at a rate of 0.2/year with poor correlation of these changes with CFC dose. WFH and FISH scores were significantly worse in those with an AJBR of >3 per year (P = 0.001). The change in the Pettersson score was significantly more in those with an AJBR of >5 per year (P = 0.020). Significant changes in FISH scores were only noted after 10 years of age. CONCLUSION: Episodic CFC replacement over a large range of doses does not alter the natural course of bleeding in haemophilia or the musculoskeletal deterioration and should not be recommended as a long term option for treatment. Prophylaxis is the only way to preserve musculoskeletal function in haemophilia.

Objective severity does not capture the impact of rosacea, acne scarring and photoaging in patients seeking laser therapy.

BACKGROUND: Measures of quality of life (QOL) and patient satisfaction are of great importance in dermatology, as both impact upon treatment adherence and health outcomes. Patients' assessment of QOL often differs from their doctors' predictions and their assessments of skin disease severity do not correlate with patients' own perceptions. The development of laser technology has facilitated successful treatment of many skin conditions, but studies on patient satisfaction are lacking. OBJECTIVES: Our aim was to determine the extent of discordance between patient and dermatologist-assessed disease severity and assess the impact of acne scarring, rosacea and photoaging on QOL. Our secondary aim was to assess patient satisfaction with laser therapy. METHODS: A prospective study of patients undergoing laser treatment for acne scarring, rosacea and photoaging was conducted over 1 year at the Skin & Cancer Foundation Australia. Subjective disease severity was determined using a visual analogue scale (VAS). Two dermatologists determined objective severity using validated grading scales to score photographs. QOL impact was measured by Skindex-16, satisfaction was measured using an amended Comprehensive Satisfaction Questionnaire (PSQ-18). RESULTS: A total of 147 individuals sought laser therapy for acne scarring, rosacea and photoaging. Dermatologists' subjective disease severity correlated weakly with patient-reported severity. All conditions negatively impacted upon QOL. Patients with rosacea had the most symptomatic impact; acne scarring was associated with the greatest self-esteem and social functioning issues; photoaging patients were the least affected. There were significant correlations between subjective severity assessment and Skindex-16 scores. There was notable discordance between dermatologist's skin severity assessment and patient's self-reported QOL impact. CONCLUSION: Skin conditions can have a profound impact on patient QOL, which is affected by patients' perception of disease severity and not fully appreciated by dermatologists' own severity assessments. Laser therapy is associated with high patient satisfaction.

Development of an online, patient-centred decision aid for patients with oropharyngeal cancer in the transoral robotic surgery era.

BACKGROUND: Radiotherapy (rt) has been the standard treatment for early oropharyngeal cancer, achieving excellent outcomes, but with significant toxicities. Transoral robotic surgery (tors) has emerged as a promising alternative. A decision aid (da) can help to establish patient treatment preferences. METHODS: A da was developed and piloted in 40 healthy adult volunteers. Assuming equal oncologic outcomes of the treatments, participants indicated their preference. The treatment trade-off point was then established, and participant perceptions were elicited. RESULTS: More than 80% of participants initially selected tors for treatment, regardless of facilitator background. For all participants, the treatment trade-off point changed after an average 15% cure benefit. Treatment toxicities, duration, novelty, and perceptions all influenced treatment selection. All subjects valued the da. CONCLUSIONS: A da developed for early oropharyngeal cancer treatment holds promise in the era of shared decision-making. Assuming equal cure rates, tors was preferred over rt by healthy volunteers.

Accelerator Measurements of Magnetically Induced Radio Emission from Particle Cascades with Applications to Cosmic-Ray Air Showers.

For 50 years, cosmic-ray air showers have been detected by their radio emission. We present the first laboratory measurements that validate electrodynamics simulations used in air shower modeling. An experiment at SLAC provides a beam test of radio-frequency (rf) radiation from charged particle cascades in the presence of a magnetic field, a model system of a cosmic-ray air shower. This experiment provides a suite of controlled laboratory measurements to compare to particle-level simulations of rf emission, which are relied upon in ultrahigh-energy cosmic-ray air shower detection. We compare simulations to data for intensity, linearity with magnetic field, angular distribution, polarization, and spectral content. In particular, we confirm modern predictions that the magnetically induced emission in a dielectric forms a cone that peaks at the Cherenkov angle and show that the simulations reproduce the data within systematic uncertainties.

Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA.

We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.