A narrative synthesis of the effectiveness and acceptability of musculoskeletal first contact physiotherapy practitioner roles in primary care

BACKGROUND

Musculoskeletal (MSK) First Contact Practitioners (FCP), diagnostic clinicians with expertise in the assessment and management of undifferentiated MSK conditions in primary care have been widely employed in the United Kingdom since 2020. The role aims to bring specialist clinical knowledge to patients at the first point of contact and reduce the burden on existing primary care services. Since the national adoption of the role, little has been published to support the effectiveness or acceptability of the role. This narrative synthesis review aims to highlight and summarise the current body of evidence.

METHODOLOGY

An adapted systematic review was carried out to inform thematic reporting and narrative synthesis, under the sub-themes of clinical outcomes, patient satisfaction, acceptability and cost analysis.

RESULTS

Eight publications were included in the review, reporting improvements in clinical outcomes in patients seen by MSK FCP, patient satisfaction and general acceptability of the role. However, all data were collected from observational studies and qualitative sources, some of which were found to be of low methodological quality.

CONCLUSION

Although the review identified consistent positivity relating to effectiveness, satisfaction and acceptability across the reviewed publications, conclusions are limited due to the relatively recent introduction of the FCP role leading to limited availability of relevant publications.

Setup Uncertainty of Pediatric Brain Tumor Patients Receiving Proton Therapy: A Prospective Study

This study quantifies setup uncertainty in brain tumor patients who received image-guided proton therapy. Patients analyzed include 165 children, adolescents, and young adults (median age at radiotherapy: 9 years (range: 10 months to 24 years); 80 anesthetized and 85 awake) enrolled in a single-institution prospective study from 2020 to 2023. Cone-beam computed tomography (CBCT) was performed daily to calculate and correct manual setup errors, once per course after setup correction to measure residual errors, and weekly after treatments to assess intrafractional motion. Orthogonal radiographs were acquired consecutively with CBCT for paired comparisons of 40 patients. Translational and rotational errors were converted from 6 degrees of freedom to a scalar by a statistical approach that considers the distance from the target to the isocenter. The 95th percentile of setup uncertainty was reduced by daily CBCT from 10 mm (manual positioning) to 1-1.5 mm (after correction) and increased to 2 mm by the end of fractional treatment. A larger variation existed between the roll corrections reported by radiographs vs. CBCT than for pitch and yaw, while there was no statistically significant difference in translational variation. A quantile mixed regression model showed that the 95th percentile of intrafractional motion was 0.40 mm lower for anesthetized patients (p=0.0016). Considering additional uncertainty in radiation-imaging isocentricity, the commonly used total plan robustness of 3 mm against positional uncertainty would be appropriate for our study cohort.

Tipifarnib Potentiates the Antitumor Effects of PI3Kα Inhibition in PIK3CA- and HRAS-Dysregulated HNSCC via Convergent Inhibition of mTOR Activity

Outcomes for patients with recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) are poor, with median overall survival (OS) ranging from 6 to 18 months. For those who progress on standard-of-care (chemo)immunotherapy, treatment options are limited, necessitating the development of rational therapeutic strategies. Toward this end, we targeted the key HNSCC drivers PI3K-mTOR and HRAS via the combination of tipifarnib, a farnesyltransferase (FTase) inhibitor, and alpelisib, a PI3Kα inhibitor, in multiple molecularly defined subsets of HNSCC. Tipifarnib synergized with alpelisib at the level of mTOR in PI3Kα- or HRAS-dependent HNSCCs, leading to marked cytotoxicity in vitro and tumor regression in vivo. On the basis of these findings, the KURRENT-HN trial was launched to evaluate the effectiveness of this combination in PIK3CA-mutant/amplified and/or HRAS-overexpressing R/M HNSCC. Preliminary evidence supports the clinical activity of this molecular biomarker-driven combination therapy. Combined alpelisib and tipifarnib has potential to benefit >45% of patients with R/M HNSCC. By blocking feedback reactivation of mTORC1, tipifarnib may prevent adaptive resistance to additional targeted therapies, enhancing their clinical utility.

SIGNIFICANCE

The mechanistically designed, biomarker-matched strategy of combining alpelisib and tipifarnib is efficacious in PIK3CA- and HRAS-dysregulated head and neck squamous carcinoma and could improve outcomes for many patients with recurrent, metastatic disease. See related commentary by Lee et al., p. 3162.

Abstract 1815: AVA6000, a novel Precision medicine, targeted to the tumor microenvironment via Fibroblast Activation Protein (FAP) mediated cleavage

AVA6000 is a therapeutic product based on proprietary pre|CISION™ technology which incorporates a substrate that is sensitive to cleavage by FAP. The pre|CISION™ substrate can be utilized in a drug conjugate linker or to generate chemotherapy prodrugs that are only activated in the tumor microenvironment. AVA6000 consists of a doxorubicin molecule covalently bonded to a dipeptide (pyridine-4-carbonyl)-D-Ala-L-Pro), which is designed to be susceptible to hydrolysis by Fibroblast Activation Protein α (FAP) but is resistant to hydrolysis by both closely related and wider mammalian peptidases. FAP, a post-prolyl endopeptidase, is overexpressed on the surface of activated fibroblastic cells which are abundant in the supporting stroma of over 90% of malignant epithelial cancers, as well as in bone and soft tissue sarcoma. While FAP is also present both in normal tissues and as a soluble enzyme in plasma, levels are significantly lower than those present in malignant epithelial cancers. Consequently, AVA6000 has the potential to deliver doxorubicin directly to the tumor microenvironment, while exposing the patient to a lesser degree of doxorubicin-associated toxicities. The primary mechanism of action of doxorubicin is thought to involve stabilisation of a topoisomerase-II-DNA cleavable complex through non-specific DNA-intercalation. The non-specific DNA-intercalation causes a number of downstream effects, which may ultimately result in apoptotic cell death. Although doxorubicin has been one of the most effective and widely used chemotherapeutic agents for the treatment of various solid malignancies for over 40 years, its clinical utility is limited by dose-limiting toxicities, including myelosuppression and cardiotoxicity. The unique FAP specificity of the N-(pyridine-4-carbonyl)-D-Ala-L-Pro leaving group conjugated to doxorubicin in AVA6000 is supported by the absence of cleavage of the fluorogenic analogue, 3114-AMC, in FAP gene-knockout mice (Fap-/-). In vitro cytotoxicity assessments involving human tumor cell lines showed that AVA6000 was between 80-fold to 4,000-fold less cytotoxic compared to doxorubicin. In several in vivo efficacy studies in tumours with high FAP levels, AVA6000 significantly decreased tumor volume and increased survival in a dose-dependent manner. In a PDX model of osteosarcoma, AVA6000 significantly decreased tumor volume while doxorubicin had no significant effect. The efficacy and tolerability profile of AVA6000 strongly support its clinical development, and a Phase I trial in patients with locally advanced or metastatic selected solid tumours in underway.

Citation Format: Fiona McLaughlin, Sarah E. Poplawski, David G. Sanford, Andrew Saunders, Jack H. Lai, Matthew Vincent, William W. Bachovchin, Neil Bell. AVA6000, a novel Precision medicine, targeted to the tumor microenvironment via Fibroblast Activation Protein (FAP) mediated cleavage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1815.

A phase 1/2 trial to evaluate the safety and antitumor activity of tipifarnib and alpelisib for patients with PIK3CA-mutated/amplified and/or HRAS-overexpressing recurrent/metastatic head and neck squamous cell carcinoma

TPS6104

Background: Understanding connections between key cellular pathways is particularly important when selecting combinatorial cancer therapies. HRAS preferentially activates PI3K 5-fold more efficiently than KRAS, while KRAS is a more efficient activator of RAF (Yan et al. 1998). Further, mutant HRAS is insufficient for oncogenic transformation if it is unable to recruit PI3K in preclinical models (Gupta et al. 2007). Conversely, mutant PI3K requires RAS to drive tumor growth (Zhao and Vogt 2008). HRAS mutation/overexpression and PIK3CA mutations/amplifications account for up to 50% of head and neck squamous cell carcinoma (HNSCC). Recognition of these interdependencies was the basis for the evaluation of HNSCC PDX models which demonstrated additive or synergistic anti-tumor effects that confirmed the codependency of these pathways, thus providing robust rationale for investigating combined pathway inhibition in the clinic. The KURRENT trial is enrolling patients with HRAS and/or PIK3CA-dependent tumors who will receive combination treatment with tipifarnib (a potent and selective inhibitor of farnesyltransferase, a critical enzyme for HRAS activity) and alpelisib, a PI3K inhibitor. Methods: The KURRENT trial (KO-TIP-013, NCT04809233) is an ongoing multicenter, open-label, 2-cohort, phase 1/2 trial designed to evaluate the safety of the combination of tipifarnib and alpelisib, determine the recommended combination dose(s) regimen, and evaluate preliminary anti-tumor activity in patients with recurrent/metastatic (R/M) HNSCC whose tumors are dependent upon HRAS and/or PIK3CA signaling. The trial will enroll 40 HNSCC patients; 20 each into two biomarker defined cohorts (Cohort 1; PIK3CA; Cohort 2; HRAS). Participants must have documented treatment failure from at least one prior therapy in the R/M setting and have measurable disease by RECIST v1.1. At the starting dose level, participants will receive tipifarnib at 300 mg twice daily on days 1-7 and 15-21 and alpelisib 200 mg each morning continuously during a 28-day cycle. The trial will use an adaptive dose escalation design (based on a Bayesian logistic regression model) to characterize safety, tolerability, and clinical activity of the combination to identify the Optimal Biologically Active Dose (OBAD) while maintaining a dose limiting toxicity (DLT) rate < 33%. No formal interim analysis is planned as the model-based dose escalation process requires decisions based on real-time evaluation of aggregate toxicity and efficacy data. All observed/available data among each cohort will be evaluated before choosing the combination dose for a subsequent cohort. Enrollment into the PIK3CA cohort began in October 2021. Clinical trial information: NCT04809233.

The First Examination of Diagnostic Performance of Automated Measurement of the Callosal Angle in 1856 Elderly Patients and Volunteers Indicates That 12.4% of Exams Met the Criteria for Possible Normal Pressure Hydrocephalus

BACKGROUND AND PURPOSE

Many patients with dementia may have comorbid or misdiagnosed normal pressure hydrocephalus, a treatable neurologic disorder. The callosal angle is a validated biomarker for normal pressure hydrocephalus with 93% diagnostic accuracy. Our purpose was to develop and evaluate an algorithm for automatically computing callosal angles from MR images of the brain.

MATERIALS AND METHODS

This article reports the results of analyzing callosal angles from 1856 subjects with 5264 MR images from the Open Access Series of Imaging Studies and the Alzheimer's Disease Neuroimaging Initiative databases. Measurement variability was examined between 2 neuroradiologists (n = 50) and between manual and automatic measurements (n = 281); from differences in simulated head orientation; and from real-world changes in patients with multiple examinations (n = 906). We evaluated the effectiveness of the automatic callosal angle to differentiate normal pressure hydrocephalus from Alzheimer disease in a simulated cohort.

RESULTS

The algorithm identified that 12.4% of subjects from these carefully screened cohorts had callosal angles of <90°, a published threshold for possible normal pressure hydrocephalus. The intraclass correlation coefficient was 0.97 for agreement between neuroradiologists and 0.90 for agreement between manual and automatic measurement. The method was robust to different head orientations. The median coefficient of variation for repeat examinations was 4.2% (Q1 = 3.1%, Q3 = 5.8%). The simulated classification of normal pressure hydrocephalus versus Alzheimer using the automatic callosal angle had an accuracy, sensitivity, and specificity of 0.87 each.

CONCLUSIONS

In even the most pristine research databases, analyses of the callosal angle indicate that some patients may have normal pressure hydrocephalus. The automatic callosal angle measurement can rapidly and objectively screen for normal pressure hydrocephalus in patients who would otherwise be misdiagnosed.

Improved Neutron Lifetime Measurement with UCNτ

We report an improved measurement of the free neutron lifetime τ_{n} using the UCNτ apparatus at the Los Alamos Neutron Science Center. We count a total of approximately 38×10^{6} surviving ultracold neutrons (UCNs) after storing in UCNτ's magnetogravitational trap over two data acquisition campaigns in 2017 and 2018. We extract τ_{n} from three blinded, independent analyses by both pairing long and short storage time runs to find a set of replicate τ_{n} measurements and by performing a global likelihood fit to all data while self-consistently incorporating the β-decay lifetime. Both techniques achieve consistent results and find a value τ_{n}=877.75±0.28_{stat}+0.22/-0.16_{syst}  s. With this sensitivity, neutron lifetime experiments now directly address the impact of recent refinements in our understanding of the standard model for neutron decay.

Safety, Antitumor Activity, and T-cell Responses in a Dose-Ranging Phase I Trial of the Oncolytic Peptide LTX-315 in Patients with Solid Tumors

PURPOSE

LTX-315 is a first-in-class, 9-mer membranolytic peptide that has shown potent immunomodulatory properties in preclinical models. We conducted a phase I dose-escalating study of intratumoral LTX-315 administration in patients with advanced solid tumors.

PATIENTS AND METHODS

Thirty-nine patients were enrolled, receiving LTX-315 injections into accessible tumors. The primary objective was to assess the safety and tolerability of this approach, with antitumor and immunomodulatory activity as secondary objectives. Tumor biopsies were collected at baseline and posttreatment for analysis of immunologic parameters.

RESULTS

The most common treatment-related grade 1-2 adverse events were vascular disorders including transient hypotension (18 patients, 46%), flushing (11 patients, 28%), and injection site reactions in 38% of patients. The most common grade 3 LTX-315-related toxicities were hypersensitivity or anaphylaxis (4 patients, 10%). Analysis of immune endpoints in serial biopsies indicated that LTX-315 induces necrosis and CD8⁺ T-cell infiltration into the tumor microenvironment. Sequencing of the T-cell receptor repertoire in peripheral blood identified significant expansion of T-cell clones after treatment, of which 49% were present in available tumor biopsies after treatment, suggesting that they were tumor associated. Substantial volume reduction (≥30%) of injected tumors occurred in 29% of the patients, and 86% (12/14 biopsies) had an increase in intralesional CD8⁺ T cells posttreatment. No partial responses by immune-related response criteria were seen, but evidence of abscopal effect was demonstrated following treatment with LTX-315.

CONCLUSIONS

LTX-315 has an acceptable safety profile, is clinically active, induces changes in the tumor microenvironment and contributes to immune-mediated anticancer activity.

Abstract OT-09-05: A randomized, pre-surgical study to investigate the biological effects of AZD9833 doses in women with ER-positive HER2-negative primary breast cancer (SERENA-3)

Background AZD9833 is an orally bioavailable selective estrogen receptor (ER) antagonist and degrader (SERD) that has shown anti-tumor efficacy in a range of preclinical breast cancer models. SERENA-1, an ongoing first-in-human study assessing AZD9833 as a monotherapy and in combination with palbociclib, established dose-dependent tolerability in pre- and post-menopausal women at doses of 25-450 mg once daily (QD), with clinical benefit and target engagement at all dose levels. Two randomized, open-label Phase 2 trials are also ongoing in women with ER+ HER2- breast cancer. SERENA-2 compares the efficacy of AZD9833 with fulvestrant in post-menopausal women with advanced breast cancer following treatment with ≤1 endocrine therapy. SERENA-3 will examine the biological effects of different doses of AZD9833 in treatment-naïve women with primary breast cancer. Methods SERENA-3 is a randomized, open-label, parallel-group, pre-surgical study to investigate the biological effects of different doses of AZD9833 in ER+, HER2- primary breast cancer. Eligible patients will be post-menopausal (and potentially pre-menopausal) women awaiting curative-intent surgery for newly diagnosed, ER+ HER2- primary breast cancer. The study is designed in two stages. In Stage 1, 24 post-menopausal women will be randomized 1:1 to receive either 75 mg or 150 mg oral AZD9833 QD for 5-7 days, followed by a minimum 5-day pre-surgery washout period; Stage 2 gives provision for additional groups depending on emerging data from Stage 1. The primary objective of this study is to explore the effect of AZD9833 on ER expression in pre- and on-treatment tumor samples from women with primary breast cancer, as assessed by immunohistochemistry and H-score. Safety and tolerability will be assessed as secondary endpoints, along with the pharmacokinetic and pharmacodynamic effects of AZD9833 on other biomarkers. Blood will be collected at screening, on the day of biopsy and the day of surgery to assess circulating tumor DNA and exploratory biomarkers. Primary endpoint analysis will be performed on the pharmacodynamic analysis set. The study will be conducted in 20 centers across 3 countries. For more information please contact Professor John Robertson at: john.robertson@nottingham.ac.uk.

Citation Format: John FR Robertson, Iain Moppett, Juan Enrique Bargalló Rocha, Giorgi Dzagnidze, Joanna Harding, Teresa Klinowska, Richard Mather, Alastair Mathewson, Rhiannon Maudsley, Christopher J Morrow, Andrew Saunders, Andy Sykes, Li Zhang, Justin PO Lindemann. A randomized, pre-surgical study to investigate the biological effects of AZD9833 doses in women with ER-positive HER2-negative primary breast cancer (SERENA-3) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr OT-09-05.

Ultracold neutron properties of the Eljen-299-02D deuterated scintillator

In this paper, we report studies of the Fermi potential and loss per bounce of ultracold neutrons (UCNs) on a deuterated scintillator (Eljen-299-02D). These UCN properties of the scintillator enable its use in a wide variety of applications in fundamental neutron research.

Parent perceptions regarding literacy instruction for students with intellectual disability

BACKGROUND

Parents offer a unique perspective as they may view literacy instruction through the lens of its direct impact on their child's daily life. Further, they are likely to provide insight into the interactions between the perceived effectiveness of instruction and their expectations for their child's success. The purposes of the current investigation were to explore perceptions of parents of children with intellectual disability (ID) related to their child's literacy instruction in schools and understand parental expectations for their child's literacy performance.

METHODS

In the current investigation, we surveyed 211 parents of children with ID in one state within the USA to identify their perceptions related to their child's literacy outcomes and instruction. The survey instrument contained 25 items including 9 multiple-choice, 12 multiple-selection, 2 open-response and 2 rank order items.

RESULTS

Data indicated significant differences across grade bands related to the type of skills students engage in learning, the importance of specific literacy skills and the challenges or barriers for students to engage in literacy instruction. The overwhelming majority of parents reported their child learning to read as very important and believe there is a difference in life outcomes between children who can read written words and those who cannot. Parents of elementary school children report barriers of disruptive behaviour, the inability of children to remain seated and distractibility more so than parents of secondary students. Parents of high school students reported a lack of instructional time more often than parents of middle and elementary school.

CONCLUSIONS

While parents across grade bands reported the importance of literacy skills for students with ID and instruction in reading comprehension, listening comprehension and vocabulary, some differences were noted. Only half the parents reported an increased focus on literacy instruction, including on essential skills (e.g. decoding), in the earlier grades. Problem behaviour and motivation served as barriers to literacy for elementary students, and a lack of instructional time served as a barrier to writing for high school students.

Final results for the neutron -asymmetry parameter A0 from the UCNA experiment

The UCNA experiment was designed to measure the neutron β-asymmetry parameter A0 using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7 T magnetic field, and then directed to a 1 T solenoidal electron spectrometer, where the decay electrons were detected in electron detector packages located on the two ends of the spectrometer. A value for A0 was then extracted from the asymmetry in the numbers of counts in the two detector packages. We summarize all of the results from the UCNA experiment, obtained during run periods in 2007, 2008–2009, 2010, and 2011–2013, which ultimately culminated in a 0.67% precision result for A0.

Turning down the heat: An enhanced understanding of the relationship between urban vegetation and surface temperature at the city scale

Guiding urban planners on the cooling returns of different configurations of urban vegetation is important to protect urban dwellers from adverse heat impacts. To this end, we estimated statistical models that fused multi-temporal very fine spatial (20 cm) and vertical (1 mm) resolution imagery, that captures the complexity of urban vegetation, with remotely sensed temperature data to assess how urban vegetation configuration influences urban temperatures. Perth, Western Australia, was used as a case-study for this analysis. Panel regression models showed that within a location an increase in tree and shrub cover has a larger cooling effect than grass coverage. On average, holding all else equal, an approximate 1 km² increase in shrub (tree) cover within a location reduces surface temperatures by 12 °C (5 °C). We included a range of robustness checks for the observed relationships between urban vegetation type and temperature. Geographically weighted regression models showed spatial variation in the cooling effect of different vegetation types; this indicates that i) unobserved factors moderate temperature-vegetation relationships across urban landscapes, and ii) that urban vegetation type and temperature relationships are complex. Machine learning models (Random Forests) were used to further explore complex and non-linear relationships between different urban vegetation configurations and temperature. The Random Forests showed that vegetation type explained 31.84% of the out-of-bag variance in summer surface temperatures, that increased cover of large vegetation within a location increases cooling, and that different configurations of urban vegetation structure can lead to cooling gains. The models in this study were trained with vegetation data capturing local detail, multiple time-periods, and entire city coverage. Thus, these models illustrate the potential to develop locally-detailed and spatially explicit tools to guide planning of vegetation configuration to optimise cooling at local- and city-scales.

B, Broussard L, Clayton S, Currie S, Dees E, Ding X, Fellers D, Fox W, Fries E, Gonzalez F, Geltenbort P, Hickerson K, Hoffbauer M, Hoffman K, Holley A, Howard D, Ito T, Komives A, Liu C, M. M, Medina J, Morley D, Morris C, O'Connor T, Penttilä S, Ramsey J, Roberts A, Salvat D, Saunders A, Seestrom S, Sharapov E, Sjue S, Snow W, Sprow A, Vanderwerp J, Vogelaar B, P.L. W, Wang Z, Weaver H, Wexler J, Womack T, Young A, Zeck B. Status of the UCN experiment

The neutron is the simplest nuclear system that can be used to probe the structure of the weak interaction and search for physics beyond the standard model. Measurements of neutron lifetime and β-decay correlation coefficients with precisions of 0.02% and 0.1%, respectively, would allow for stringent constraints on new physics. The UCNτ experiment uses an asymmetric magneto-gravitational UCN trap with in situ counting of surviving neutrons to measure the neutron lifetime, τn = 877.7s (0.7s)stat (+0.4/−0.2s)sys. We discuss the recent result from UCNτ, the status of ongoing data collection and analysis, and the path toward a 0.25 s measurement of the neutron lifetime with UCNτ.

Search for neutron dark decay: n → χ + e+e−

In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e+e− pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel.

Search for the Neutron Decay n→X+γ, Where X is a Dark Matter Particle

Fornal and Grinstein recently proposed that the discrepancy between two different methods of neutron lifetime measurements, the beam and bottle methods, can be explained by a previously unobserved dark matter decay mode, n→X+γ. We perform a search for this decay mode over the allowed range of energies of the monoenergetic γ ray for X to be dark matter. A Compton-suppressed high-purity germanium detector is used to identify γ rays from neutron decay in a nickel-phosphorous-coated stainless-steel bottle. A combination of Monte Carlo and radioactive source calibrations is used to determine the absolute efficiency for detecting γ rays arising from the dark matter decay mode. We exclude the possibility of a sufficiently strong branch to explain the lifetime discrepancy with 97% confidence.

Measurement of the neutron lifetime using a magneto-gravitational trap and in situ detection

The precise value of the mean neutron lifetime, τ_n, plays an important role in nuclear and particle physics and cosmology. It is used to predict the ratio of protons to helium atoms in the primordial universe and to search for physics beyond the Standard Model of particle physics. We eliminated loss mechanisms present in previous trap experiments by levitating polarized ultracold neutrons above the surface of an asymmetric storage trap using a repulsive magnetic field gradient so that the stored neutrons do not interact with material trap walls. As a result of this approach and the use of an in situ neutron detector, the lifetime reported here [877.7 ± 0.7 (stat) +0.4/-0.2 (sys) seconds] does not require corrections larger than the quoted uncertainties.

Measurement of the neutron lifetime using a magneto-gravitational trap and in situ detection

The precise value of the mean neutron lifetime, τ_n, plays an important role in nuclear and particle physics and cosmology. It is used to predict the ratio of protons to helium atoms in the primordial universe and to search for physics beyond the Standard Model of particle physics. We eliminated loss mechanisms present in previous trap experiments by levitating polarized ultracold neutrons above the surface of an asymmetric storage trap using a repulsive magnetic field gradient so that the stored neutrons do not interact with material trap walls. As a result of this approach and the use of an in situ neutron detector, the lifetime reported here [877.7 ± 0.7 (stat) +0.4/-0.2 (sys) seconds] does not require corrections larger than the quoted uncertainties.