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Studies of galaxy surveys in the context of the cold dark matter paradigm have shown that the mass of the dark matter halo and the total stellar mass are coupled through a function that varies smoothly with mass. Their average ratio Mhalo/Mstars has a minimum of about 30 for galaxies with stellar masses near that of the Milky Way (approximately 5 × 1010 solar masses) and increases both towards lower masses and towards higher masses. The scatter in this relation is not well known; it is generally thought to be less than a factor of two for massive galaxies but much larger for dwarf galaxies. Here we report the radial velocities of ten luminous globular-cluster-like objects in the ultra-diffuse galaxy NGC1052-DF2, which has a stellar mass of approximately 2 × 108 solar masses. We infer that its velocity dispersion is less than 10.5 kilometres per second with 90 per cent confidence, and we determine from this that its total mass within a radius of 7.6 kiloparsecs is less than 3.4 × 108 solar masses. This implies that the ratio Mhalo/Mstars is of order unity (and consistent with zero), a factor of at least 400 lower than expected. NGC1052-DF2 demonstrates that dark matter is not always coupled with baryonic matter on galactic scales.
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BACKGROUND: Using information and communication technologies to seek, discuss, and share health-related information influences people's trust and knowledge of several health practices. However, we know little about the associations between individuals' information and communication technology use and their perceptions of trust and knowledge of clinical trials. Examining these associations may lead to the identification of target audiences and channels for developing effective educational interventions and campaigns about clinical trials. METHODS: In this study, we analyzed Health Information National Trends Survey data to document perceptions of clinical trial-related knowledge and trust that were recently added as questions in this annual national survey of US adults. We also examined correlates of these clinical trial perceptions that included sociodemographic factors and individuals' use of information and communication technologies to seek health information, discuss such information with their healthcare providers, and share the information in their network. RESULTS: More than 90% of participants had no or limited perceived knowledge about clinical trials. Knowledge was higher among those who seek or discuss health-related information online. Differences in perceived knowledge and trust emerged for some racial/ethnic subgroups and other demographic factors. Providers were considered the most trusted source of information (73.6%), followed by health organizations (19.4%) and social support (7.1%). Trust in health organizations compared to health providers was higher among those who used online resources to share health information online with others. Trust in social support was significantly higher among those who used information and communication technologies to communicate about health. CONCLUSION: Based on these findings, we recommend developing online resources about clinical trials to be distributed through social media. These resources should facilitate a dialogue and be targeted to several groups considering their information and communication technologies' use.
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Ensaios Clínicos como Assunto , Confiança , Adulto , Humanos , Comunicação , Comportamentos Relacionados com a Saúde , Inquéritos e Questionários , Tecnologia , Tecnologia da InformaçãoRESUMO
BACKGROUND: The Multicenter Selective Lymphadenectomy Trial-II (MSLT-II) revealed completion lymph node dissection (CLND) after positive sentinel lymph node biopsy (SLNB) did not improve melanoma-specific survival compared with surveillance. Given these findings and the morbidity associated with CLND, this study investigated trends in rates and predictors of CLND after MSLT-II. METHODS: Analysis of the National Cancer Database was performed for all patients aged ≥18 years with melanoma and a positive SLNB for 2012-2019. Rates of CLND before and after publication of MSLT-II were identified and logistic regression used to identify factors associated with CLND. RESULTS: Patients undergoing CLND declined from 55.9% pre-MSLT-II (n = 9725) to 19.5% post-MSLT-II (n = 9419) (odds ratio [OR] 0.32, 95% confidence interval [CI] 0.29-0.35). CLND was less likely in females (OR 0.83; 95% CI 0.78-0.89), older patients (vs. 18-39 yr; 40-64 yr OR 0.80, 95% CI 0.65-0.98; 65-79 yr OR 0.67, 95% CI 0.53-0.84; >80 yr OR 0.38, 95% CI 0.30-0.49), sicker patients (Deyo category ≥2 OR 0.85, 95% CI 0.73-0.99), thinner primary lesions (vs. 0.01-0.79 mm; 1.01-4.00 mm OR 1.16, 95% CI 1.01-1.33; ≥4.01 mm OR 1.31, 95% CI 1.08-1.59), patients from metro areas (Rural OR 1.31, 95% CI 1.00-1.70; Urban OR 1.15, 95% CI 1.03-1.29), and those treated at lower-volume centers (vs. lowest-volume; highest-volume OR 1.31, 95% CI 1.14-1.50; high-volume OR 1.40, 95% CI 1.24-1.57). CONCLUSIONS: MSLT-II has impacted clinical care; however, male gender, thicker lesions, rural/urban residence, younger age, fewer comorbidities, and treatment at higher-volume centers confer a greater likelihood of undergoing CLND. Further investigations should focus on whether these populations benefit from more aggressive surgical care.
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Melanoma , Linfonodo Sentinela , Neoplasias Cutâneas , Feminino , Humanos , Masculino , Estados Unidos/epidemiologia , Adolescente , Adulto , Melanoma/patologia , Excisão de Linfonodo , Biópsia de Linfonodo Sentinela , Bases de Dados Factuais , Probabilidade , Neoplasias Cutâneas/patologia , Linfonodo Sentinela/patologiaRESUMO
BACKGROUND: Rates of melanoma have increased dramatically in the United States over the past 25 years, and it has become among the most prevalent cancers for young adult women. Intentional skin tanning leads to a pattern of intense and intermittent UV radiation exposure that is associated with increased risk of melanoma. Frequent tanning is most common among young women and is linked to a variety of sociocultural pressures that negatively impact body image and drive appearance control behaviors. Unfortunately, there are no established interventions designed for frequent tanners. This intervention addresses this gap with unique content informed by body image and acceptance-based interventions. The intervention is delivered using Facebook secret groups, an approach designed to support behavior change and ensure scalability. OBJECTIVE: This study aims to describe the rationale and methodology of a randomized controlled trial of a melanoma prevention program targeting young women engaged in frequent indoor or outdoor UV tanning. METHODS: Participants are women aged 18-25 years who report high-risk tanning (ie, at least 10 indoor tanning sessions in the past 12 months or 10 outdoor sessions in the previous summer). After recruitment and screening, participants completed a baseline survey and were randomly assigned to receive the intervention or an attention-matched control condition. Both conditions were 8-week-long Facebook groups (approximately 25 members each) with daily posting of content. Follow-up surveys are administered at 3, 8, and 18 months after baseline. The primary trial outcome is the combined number of indoor and outdoor tanning sessions reported at the 8-month follow-up. Hypothesized intervention mediators are assessed at the 3-month follow-up. RESULTS: This project was funded by a National Cancer Institute award (R01 CA218068), and the trial procedures were approved by the University of Kentucky Institutional Review Board in February 2020. Trial recruitment and enrollment occurred in 6 waves of data collection, which started in February 2022 and closed in May 2023. The study is closed to enrollment but remains open for follow-ups, and this protocol report was prepared before data analyses. As of February 2024, all participants have completed the 8-month follow-up assessment, and data collection is scheduled to close by the end of 2024 after the collection of the 18-month follow-up. CONCLUSIONS: This trial will contribute unique knowledge to the field of skin cancer prevention, as no fully powered trials have examined the efficacy of an intervention designed for frequent indoor or outdoor tanning. The trial may also contribute evidence of the value in translating principles of body image and acceptance-based interventions into the field of skin cancer prevention and beyond. If successful, the use of the Facebook platform is intended to aid in dissemination as it provides a way to embed the intervention into individuals' everyday routines. TRIAL REGISTRATION: ClinicalTrials.gov NCT03441321; https://clinicaltrials.gov/study/NCT03441321. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/56562.
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Clinical trials are essential to modern medicine, but several barriers, including poor communication, hamper their successful completion. We examined the prevalence and correlates of invitation to participate in clinical trials among a nationally-representative sample of US adults using survey responses from the 2020 HINTS (Cycle 5). Analyses were conducted in 2021. Overall, 9% of respondents reported being invited to a clinical trial, a prevalence that is nearly half of previously reported rates in convenience samples recruited from health care settings. Compared to non-Hispanic Whites, Black respondents reported the higher prevalence of invitation (16.0%) whereas Asian respondents reported the lowest (2%). Prevalence of clinical trial invitation was significantly higher for the 65-74 age and the 75 + age groups. Prevalence of invitation was significantly higher among college graduates (12.0%) and lower for those residing in rural areas/small towns compared to metropolitan areas. Invitation was significantly higher among cancer patients/survivors (16.0%), patients with diabetes (11.7%) and with chronic lung disease (16.7%). Provider and patient factors there were associated with higher invitation rates included using web devices to communicate with providers or to aid health-related discussions, having a specific medical provider, and looking for health information online. This study establishes a population-based prevalence of clinical trial communication that can be monitored as health care providers/organizations increase their focus on enrollment activities. Targeted interventions to improve communication about clinical trials are needed to address socio-demographic disparities and are particularly important for Asian patients, patients with lower income, and those living in rural areas.