Direct Observations of the Ionizing Star in the UC HII Region G29.96-0.02: A Strong Constraint on the Stellar Birth Line for Massive Stars

We have observed the ultracompact HII region G29.96-0.02 in the near infrared J, H, and K bands and in the Br-gamma line. By comparison with radio observations, we determine that the extinction to the nebula is AK = 2.14 with a 3 sigma uncertainty of 0.25. We identify the ionizing star and determine its intrinsic K magnitude. The star does not have an infrared excess and so appears to be no longer accreting. The K magnitude and the bolometric luminosity allow us to place limits on the location of the ionizing star in the HR diagram. The 3 sigma upper limit on the effective temperature of the ionizing star is 42500 K. We favor a luminosity appropriate for star with a mass in excess of about 60 solar masses. The limit on the temperature and luminosity exclude stars on the ZAMS and stars within 10^6 yr of the ZAMS. Since the age of the UC HII region is estimated to be only about 10^5 yr, we suggest that this is direct evidence that the stellar birth line for massive stars at twice solar metallicity must be significantly redder than the ZAMS.Comment: 42 pages; LaTex; 11 Postscript figures; accepted for publication in Ap

Using Three-Dimensional Printed Models for Trainee Orbital Fracture Education

BACKGROUND: Three-dimensional printing is an underutilized technology in ophthalmology training; its use must be explored in complex educational scenarios. This study described a novel approach to trainee education of orbital fracture repair utilizing three-dimensional (3D) printed models as a teaching tool. METHODS: Ophthalmology residents and oculoplastic fellows from multiple training institutions underwent an educational session on orbital fractures, learning through four different models. Participants analyzed orbital fractures through computerized tomography (CT) imaging alone and then utilizing CT imaging with the aid of a 3D printed model. Participants completed a questionnaire assessing their understanding of the fracture pattern and surgical approach. After the training, participants were surveyed on the impact of the educational session. Components of the training were rated by participants on a 5-point Likert scale. RESULTS: A statistically significant difference (p \u3c .05) was found in participant confidence conceptualizing the anatomic boundaries of the fracture and planning the orbital fracture approach for repair of three out of four models on pre-test post-test analysis. On exit questionnaire, 84.3% of participants thought the models were a useful tool for surgical planning, 94.8% of participants thought the models were a useful tool for conceptualizing the anatomic boundaries of the fracture, 94.8% of participants thought the models were a useful tool for orbital fracture training, and 89.5% of participants thought the exercise was helpful. CONCLUSION: This study supports the value of 3D printed models of orbital fractures as an effective tool for ophthalmology trainee education to improve understanding and visualization of complex anatomical space and pathology. Given the limited opportunities trainees may have for hands-on orbital fracture practice, 3D printed models provide an accessible way to enhance training

Polyunsaturated fatty acid status and methylmercury exposure are not associated with leukocyte telomere length in mothers or their children in the Seychelles Child Development Study

Background: Leukocyte telomere length (TL) is associated with age-related diseases and early mortality, but there is a lack of data on the determinants of TL in early life. Evidence suggests that dietary intake ofmarine n-3 (v-3) polyunsaturated fatty acids (PUFAs) is protective of telomere attrition, yet the effect of methylmercury exposure, also found in fish, on TL is unknown. Objective: The aim of this study was to investigate the associations between prenatal PUFA status, methylmercury exposure, and TL in mothers and children in the SCDS (Seychelles Child Development Study), for whom fish consumption is high. Methods: Blood samples collected from 229 mothers (at 28 wk gestation and delivery) and children (at 5 y of age) in the SCDS first nutrition cohort were analyzed for PUFA concentrations. Prenatal mercury was measured in maternal hair collected at delivery. Postnatalmercury was alsomeasured in children's hair samples with the use of a cumulativemetric derived from values obtained at 3-5 y of age. Relative TL wasmeasured in blood obtained from mothers at delivery, in cord blood, and in children at 5 y of age by quantitative polymerase chain reaction. Linear regression models were used to investigate the associations between PUFA status, methylmercury exposure, and TL. Results: Neither prenatal PUFA status or methylmercury exposure was associated with TL of the mother or child or with TL attrition rate. However, a higher prenatal n-6:n-3 PUFA ratiowas significantly associated with longer TLs in the mothers (β = 0.001, P = 0.048). Child PUFA status andmethylmercury exposurewere not associated with child TL. However, higher family Hollingshead socioeconomic status (SES) scores at 9 mo of agewere significantly associatedwith longer TLs in cord blood (β = 0.005, P=0.03). Conclusions: We found no evidence that PUFA status or methylmercury exposure are determinants of TL in either the mother or child. However, our results support the hypothesis that family SES may be associated with child TL

Natural T cell–mediated protection against seasonal and pandemic Influenza: results of the Flu Watch cohort study

Rationale: A high proportion of influenza infections are asymptomatic. Animal and human challenge studies and observational studies suggest T cells protect against disease among those infected, but the impact of T-cell immunity at the population level is unknown. Objectives: To investigate whether naturally preexisting T-cell responses targeting highly conserved internal influenza proteins could provide cross-protective immunity against pandemic and seasonal influenza. Methods: We quantified influenza A(H3N2) virus–specific T cells in a population cohort during seasonal and pandemic periods between 2006 and 2010. Follow-up included paired serology, symptom reporting, and polymerase chain reaction (PCR) investigation of symptomatic cases. Measurements and Main Results: A total of 1,414 unvaccinated individuals had baseline T-cell measurements (1,703 participant observation sets). T-cell responses to A(H3N2) virus nucleoprotein (NP) dominated and strongly cross-reacted with A(H1N1)pdm09 NP (P < 0.001) in participants lacking antibody to A(H1N1)pdm09. Comparison of paired preseason and post-season sera (1,431 sets) showed 205 (14%) had evidence of infection based on fourfold influenza antibody titer rises. The presence of NP-specific T cells before exposure to virus correlated with less symptomatic, PCR-positive influenza A (overall adjusted odds ratio, 0.27; 95% confidence interval, 0.11–0.68; P = 0.005, during pandemic [P = 0.047] and seasonal [P = 0.049] periods). Protection was independent of baseline antibodies. Influenza-specific T-cell responses were detected in 43%, indicating a substantial population impact. Conclusions: Naturally occurring cross-protective T-cell immunity protects against symptomatic PCR-confirmed disease in those with evidence of infection and helps to explain why many infections do not cause symptoms. Vaccines stimulating T cells may provide important cross-protective immunity

Lower respiratory tract myeloid cells harbor SARS-CoV-2 and display an inflammatory phenotype

SARS-CoV-2 pneumonia may induce an aberrant immune response with brisk recruitment of myeloid cells into the airspaces. Although the clinical implications are unclear, others have suggested that infiltrating myeloid cells may contribute to morbidity and mortality during SARS-CoV-2 infection.1–3 However, few reports have characterized myeloid cells from the lower respiratory tract, which appears to be the primary site of viral-induced pathology, during severe SARS-CoV-2 pneumonia