Centerscope

Centerscope, formerly Scope, was published by the Boston University Medical Center "to communicate the concern of the Medical Center for the development and maintenance of improved health care in contemporary society.

Comparison of heavy-ion transport simulations: Collision integral with pions and Δ resonances in a box

We compare ten transport codes for a system confined in a box, aiming at improved handling of the production of $\Delta$ resonances and pions, which is indispensable for constraining high-density symmetry energy from observables such as the $\pi^-/\pi^+$ yield ratio in heavy-ion collisions. The system in a box is initialized with nucleons at saturation density and at 60 MeV temperature. The reactions $NN\leftrightarrow N\Delta$ and $\Delta\leftrightarrow N\pi$ are implemented, but the Pauli blocking and the mean-field potential are deactivated in the present comparison. Results are compared to those from the two reference cases of a chemically equilibrated ideal gas mixture and of the rate equation. In the results of the numbers of $\Delta$ and $\pi$, deviations from the reference values are observed in many codes, and they depend significantly on the size of the time step. These deviations are tied to different ways in ordering the sequence of collisions and decays, that take place in the same time step. Better agreements are seen in the reaction rates and the number ratios among the isospin species of $\Delta$ and $\pi$. These are, however, affected by the correlations, which are absent in the Boltzmann equation, but are induced by the way particle scatterings are treated in transport calculations. The uncertainty in the transport-code predictions of the $\pi^-/\pi^+$ ratio for the system initialized at n/p = 1.5, after letting the existing $\Delta$ resonances decay, is found to be within a few percent, which is sufficiently small so that it does not strongly impact constraining the high-density symmetry energy from heavy-ion collisions. Most of the sources of uncertainties have been understood, and individual codes may be further improved. This investigation will be extended in the future to heavy-ion collisions to ensure the problems identified here remain under control.Comment: 36 pages, 27 figures; a new Fig. 21 and revised results from some codes, achieving improved and consistent understandin

Comparison of heavy-ion transport simulations: Collision integral in a box

Simulations by transport codes are indispensable to extract valuable physical information from heavy-ion collisions. In order to understand the origins of discrepancies among different widely used transport codes, we compare 15 such codes under controlled conditions of a system confined to a box with periodic boundary, initialized with Fermi-Dirac distributions at saturation density and temperatures of either 0 or 5 MeV. In such calculations, one is able to check separately the different ingredients of a transport code. In this second publication of the code evaluation project, we only consider the two-body collision term; i.e., we perform cascade calculations. When the Pauli blocking is artificially suppressed, the collision rates are found to be consistent for most codes (to within 1 % or better) with analytical results, or completely controlled results of a basic cascade code. In orderto reach that goal, it was necessary to eliminate correlations within the same pair of colliding particles that can be present depending on the adopted collision prescription. In calculations with active Pauli blocking, the blocking probability was found to deviate from the expected reference values. The reason is found in substantial phase-space fluctuations and smearing tied to numerical algorithms and model assumptions in the representation of phase space. This results in the reduction of the blocking probability in most transport codes, so that the simulated system gradually evolves away from the Fermi-Dirac toward a Boltzmann distribution. Since the numerical fluctuations are weaker in the Boltzmann-Uehling-Uhlenbeck codes, the Fermi-Dirac statistics is maintained there for a longer time than in the quantum molecular dynamics codes. As a result of this investigation, we are able to make judgements about the most effective strategies in transport simulations for determining the collision probabilities and the Pauli blocking. Investigation in a similar vein of other ingredients in transport calculations, like the mean-field propagation or the production of nucleon resonances and mesons, will be discussed in the future publications

PC-1 Nucleoside Triphosphate Pyrophosphohydrolase Deficiency in Idiopathic Infantile Arterial Calcification

Inogranic pyrophosphate (PPi) inhibits hydroxyapatite deposition, and mice deficient in the PPi-generating nucleoside triphosphate pyrophosphohydrolase (NTPPPH) Plasma cell membrane glycoprotein-1 (PC-1) develop peri-articular and arterial calcification in early life. In idiopathic infantile arterial calcification (IIAC), hydroxyapatite deposition and smooth muscle cell (SMC) proliferation occur, sometimes associated with peri-articular calcification. Thus, we assessed PC-1 expression and PPi metabolism in a 25-month-old boy with IIAC and peri-articular calcifications. Plasma PC-1 was <1 ng/ml by enzyme-linked immunosorbent assay in the proband, but 10 to 30 ng/ml in unaffected family members and controls. PC-1 functioned to raise extracellular PPi in cultured aortic SMCs. However, PC-1 was sparse in temporal artery lesion SMCs in the proband, unlike the case for SMCs in atherosclerotic carotid artery lesions of unrelated adults. Proband plasma and explant-cultured dermal fibroblast NTPPPH and PPi were markedly decreased. The proband was heterozygous at the PC-1 locus, and sizes of PC-1 mRNA and polypeptide, and the PC-1 mRNA-coding region sequence were normal in proband fibroblasts. However, immunoreactive PC-1 protein was relatively sparse in proband fibroblasts. In conclusion, deficient extracellular PPi and a deficiency of PC-1 NTPPPH activity can be associated with human infantile arterial and peri-articular calcification, and may help explain the sharing of certain phenotypic features between some IIAC patients and PC-1-deficient mice

Advanced nodal stage predicts venous thromboembolism in patients with locally advanced non-small cell lung cancer

Objectives: Patients with non-small cell lung cancer (NSCLC) are known to be at high risk for venous thromboembolism (VTE), but previous studies have not specifically analyzed locally advanced disease. We performed a retrospective VTE risk analysis in a cohort of locally advanced NSCLC treated with definitive intent including radiation therapy. Materials and Methods: The cohort consisted of 629 patients with stage II-III NSCLC treated at a single institution from January 2003 to December 2012. All patients received treatment with curative intent, including radiation therapy. Fine and Gray’s competing-risks regression model, accounting for death and distant metastasis as competing risks, was used to identify significant predictors of VTE risk, and cumulative incidence estimates were generated using the competing-risks model. Results and Conclusion: At a median follow-up of 31 months, 127 patients developed a VTE, with 80% of events occurring in the first year after treatment initiation. 1-year and 3-year overall cumulative incidence estimates were 13.5% and 15.4%, respectively. On univariate analysis, stage IIIB and N3 nodal disease were associated with increased VTE risk. In the final multivariable model, N3 nodal disease was associated with increased VTE risk (Hazard ratio 1.64; 95% CI 1.06-2.54; p=0.027). In conclusion, patients with locally advanced NSCLC are at high risk for VTE, especially in the first year after treatment initiation, with a 1-year cumulative incidence of 13.5%. N3 nodal staging was associated with significantly higher VTE risk compared to N0-N2 staging

Effect of a baby-friendly workplace support intervention on exclusive breastfeeding in Kenya

Exclusive breastfeeding (EBF) during the first 6 months of life is crucial for optimizing child growth, development and survival, as well as the mother's wellbeing. Mother's employment may hinder optimal breastfeeding, especially in the first 6 months. We assessed the effectiveness of a baby-friendly workplace support intervention on EBF in Kenya. This pre-post intervention study was conducted between 2016 and 2018 on an agricultural farm in Kericho County. The intervention targeted pregnant/breastfeeding women residing on the farm and consisted of workplace support policies and programme interventions including providing breastfeeding flexi-time and breaks for breastfeeding mothers; day-care centres (crèches) for babies near the workplace and lactation centres with facilities for breast milk expression and storage at the crèches; creating awareness on available workplace support for breastfeeding policies; and home-based nutritional counselling for pregnant and breastfeeding women. EBF was measured through 24-h recall. The effect of the intervention on EBF was estimated using propensity score weighting. The study included 270 and 146 mother-child dyads in the nontreated (preintervention) group and treated (intervention) group, respectively. The prevalence of EBF was higher in the treated group (80.8%) than in the nontreated group (20.2%); corresponding to a fourfold increased probability of EBF [risk ratio (RR) 3.90; 95% confidence interval (CI) 2.95-5.15]. The effect of the intervention was stronger among children aged 3-5 months (RR 8.13; 95% CI 4.23-15.64) than among those aged &lt;3 months (RR 2.79; 95% CI 2.09-3.73). The baby-friendly workplace support intervention promoted EBF especially beyond 3 months in this setting.</p

Outcomes by Tumor Histology and KRAS Mutation Status After Lung Stereotactic Body Radiation Therapy for Early-Stage Non–Small-Cell Lung Cancer

BACKGROUND: We analyzed outcomes after lung stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung-carcinoma (NSCLC) by histology and KRAS genotype. PATIENTS AND METHODS: We included 75 patients with 79 peripheral tumors treated with SBRT (18 Gy × 3 or 10 to 12 Gy × 5) at our institution from 2009 to 2012. Genotyping for KRAS mutations was performed in 10 patients. Outcomes were analyzed by the Kaplan-Meier method/Cox regression, or cumulative incidence method/Fine-Gray analysis. RESULTS: The median patient age was 74 (range, 46 to 93) years, and Eastern Cooperative Oncology Group performance status was 0 to 1 in 63%. Tumor histology included adenocarcinoma (44%), squamous cell carcinoma (25%), and NSCLC (18%). Most tumors were T1a (54%). Seven patients had KRAS-mutant tumors (9%). With a median follow-up of 18.8 months among survivors, the 1-year estimate of overall survival was 88%, cancer-specific survival (CSS) 92%, primary tumor control 94%, and freedom from recurrence (FFR) 67%. In patients with KRAS-mutant tumors, there was a significantly lower tumor control (67% vs. 96%; P = .04), FFR (48% vs. 69%; P = .03), and CSS (75% vs. 93%; P = .05). On multivariable analysis, histology was not associated with outcomes, but KRAS mutation (hazard ratio, 10.3; 95% confidence interval, 2.3-45.6; P = .0022) was associated with decreased CSS after adjusting for age. CONCLUSION: In this SBRT series, histology was not associated with outcomes, but KRAS mutation was associated with lower FFR on univariable analysis and decreased CSS on multivariable analysis. Because of the small sample size, these hypothesis-generating results need to be studied in larger data sets

Perceptions towards management of acute malnutrition by community health volunteers in northern Kenya.

Child undernutrition is a persistent challenge in arid and semi-arid areas due to low and erratic rainfall, recurrent droughts and food insecurity. In these settings, caregivers face several challenges in accessing health services for sick and/or malnourished children, including long distances to health facilities, harsh terrain, and lack of money to pay for transportation costs to the health facilities, leading to low service coverage and sub-optimal treatment outcomes. To address these challenges and optimize treatment outcomes, the World Health Organization recommends utilizing community health volunteers (CHVs) to manage acute malnutrition in the community. This study explored the perceptions of community members regarding acute malnutrition treatment by CHVs in Turkana and Isiolo counties in Kenya. The study utilized a cross-sectional study design and included a purposive sample of caregivers of children, CHVs, officers who trained and supervised CHVs and community leaders in the intervention area. Focus group discussions and key informant interviews were used to explore perceptions towards the management of acute malnutrition by CHVs. Generally, caregivers and CHVs perceived the intervention to be beneficial as it readily addressed acute malnutrition treatment needs in the community. The intervention was perceived to be acceptable, effective, and easily accessible. The community health structure provided a platform for commodity supply and management and CHV support supervision. This was a major enabler in implementing the intervention. The intervention faced operational and systemic challenges that should be considered before scale-up

Comparing pion production in transport simulations of heavy-ion collisions at 270A MeV under controlled conditions

International audienceWithin the Transport Model Evaluation Project (TMEP), we present a detailed study of Sn+Sn collisions at 270A MeV, which are representative reactions used to study the equation of state at suprasaturation densities. We put particular emphasis on the production of pions and $\Delta$ resonances, which have been used as probes of the nuclear symmetry energy. In this study, we prescribe a common and rather simple physical model, and follow in detail the results of 4 Boltzmann-Uehling-Uhlenbeck (BUU) models and 6 quantum molecular dynamics (QMD) models. We find that the nucleonic evolution of the collision and the nucleonic observables in these codes do not completely converge, but that the differences among the codes can be understood as being due to several reasons: the basic differences between BUU and QMD models in the representation of the phase-space distributions, computational differences in the mean-field evaluation, and differences in the adopted strategies for the Pauli blocking in the collision integrals. For pionic observables, we find that a higher maximum density leads to an enhanced pion yield and a reduced $\pi^-/\pi^+$ yield ratio, while a more effective Pauli blocking generally leads to a slightly suppressed pion yield and an enhanced $\pi^-/\pi^+$ yield ratio, although differences in its implementations do not have a dominating role in the differences among the codes. We specifically investigate the effect of the Coulomb force, and find that it increases the total $\pi^-/\pi^+$ yield ratio but reduces the ratio at high pion energies. Using only the results of codes that strictly follow the homework specifications, we find a convergence of the codes in the final charged pion yield ratio to less than $15\%$, while the uncertainty is expected to be reduced to about $4\%$ if the same or similar ingredients are incorporated in each code