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1.
Phys Rev Lett ; 127(23): 235001, 2021 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-34936794

RESUMEN

Understanding how atoms interact with hot dense matter is essential for astrophysical and laboratory plasmas. Interactions in high-density plasmas broaden spectral lines, providing a rare window into interactions that govern, for example, radiation transport in stars. However, up to now, spectral line-shape theories employed at least one of three common approximations: second-order Taylor treatment of broadening operator, dipole-only interactions between atom and plasma, and classical treatment of perturbing electrons. In this Letter, we remove all three approximations simultaneously for the first time and test the importance for two applications: neutral hydrogen and highly ionized magnesium and oxygen. We found 15%-50% change in the spectral line widths, which are sufficient to impact applications including white-dwarf mass determination, stellar-opacity research, and laboratory plasma diagnostics.

2.
Phys Rev Lett ; 124(5): 055003, 2020 Feb 07.
Artículo en Inglés | MEDLINE | ID: mdl-32083926

RESUMEN

Accurate calculation of spectral line broadening is important for many hot, dense plasma applications. However, calculated line widths have significantly underestimated measured widths for Δn=0 lines of Li-like ions, which is known as the isolated-line problem. In this Letter, scrutinization of the line-width derivation reveals that the commonly used expression neglects a potentially important contribution from electron-capture. Line-width calculations including this process are performed with two independent codes, both of which removed the discrepancies at temperatures below 10 eV. The revised calculations also suggest the remaining discrepancy scales more strongly with electron temperature than the atomic number as was previously suggested.

3.
J Public Health (Oxf) ; 42(2): 416-422, 2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32052033

RESUMEN

BACKGROUND: This study assesses whether increased coverage of the measles, mumps and rubella (MMR) vaccination differs between areas where school nurses deliver catch-up MMR doses to adolescents in school settings, compared to signposting to general practice. METHODS: A retrospective cohort study was conducted using Child Health Information Services records within the NHS England South (South Central) commissioning boundary. The sample population included children born 1 September 2000-31 August 2001, in school year 9 during the 2014-15 academic year. RESULTS: The primary outcome findings show an increase in coverage of at least one dose of MMR by 1.6% (n = 334) in the cohort receiving catch-up MMR, compared to 0.2% (n = 12) in the cohort signposted to general practice. Over time, the difference in increase between the two cohorts was 1.4%, analysed using the chi-squared comparison of proportions test, providing strong evidence (P < 0.0001) that school nurse delivery of catch-up MMR is effective at increasing coverage. The findings also suggest that school nurse delivery of catch-up MMR may benefit Black, Asian and minority ethnic children and those from more deprived backgrounds. CONCLUSIONS: It is recommended that commissioners of school-aged immunization services incorporate the delivery of catch-up MMR doses in their contracts with school nurses.


Asunto(s)
Medicina General , Sarampión , Enfermeras y Enfermeros , Adolescente , Niño , Inglaterra , Humanos , Vacuna contra el Sarampión-Parotiditis-Rubéola , Estudios Retrospectivos , Instituciones Académicas
4.
Public Health ; 185: 261-263, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32693249

RESUMEN

BACKGROUND: There is emerging evidence about characteristics that may increase the risk of coronavirus disease 2019 (COVID-19) mortality, but they are highly correlated. METHODS: An ecological analysis was used to estimate associations between these variables and age-standardised COVID-19 mortality rates at the local authority level. RESULTS: Ethnicity, population density and overweight/obesity were all found to have strong independent associations with COVID-19 mortality, at the local authority level. DISCUSSION: This analysis provides some preliminary evidence about which variables are independently associated with COVID-19 mortality and suggests that others (deprivation and pollution) are not directly linked. It highlights the importance of multivariate analyses to understand the factors that increase vulnerability to COVID-19.


Asunto(s)
Infecciones por Coronavirus/mortalidad , Disparidades en el Estado de Salud , Neumonía Viral/mortalidad , Contaminación del Aire/efectos adversos , Contaminación del Aire/estadística & datos numéricos , COVID-19 , Inglaterra/epidemiología , Etnicidad/estadística & datos numéricos , Humanos , Mortalidad/tendencias , Análisis Multivariante , Obesidad/epidemiología , Pandemias , Densidad de Población , Factores de Riesgo , Factores Socioeconómicos
5.
Artículo en Inglés | MEDLINE | ID: mdl-32116394

RESUMEN

Analytic fits to the recommended electron-impact excitation and ionization cross sections for Be I are presented. The lowest 19 terms of configurations 2snl (n ≤ 4) and 2p 2 terms below the first ionization limit are considered. The fits are based on the accurate calculations with the convergent close coupling (CCC) method as well as the B-spline R-matrix (BSR) approach. The fitted cross sections provide rate coefficients that are believed to approximate the original data within 10% with very few exceptions. The oscillator strengths for the dipole-allowed transitions between all the considered states are calculated with the relativistic multi-configuration Dirac-Hartree-Fock (MCDHF) approach and compared with the CCC and BSR results. This comparison shows a very good agreement except for a handful of cases with likely strong cancellations.

6.
Public Health ; 170: 133-139, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31039467

RESUMEN

OBJECTIVE: Adolescents are at risk of developing detrimental health behaviours that will affect their adult health. The aim was to estimate prevalence of health risk behaviours (HRB), comparing young people (12-18 years old) in Wiltshire (UK) who are vulnerable (looked after children, special education needs and disabilities, young carers and military dependents) to those who are not vulnerable and assess whether these behaviours are associated with protective factors (e.g. friendship groups). STUDY DESIGN: Secondary analysis of cross-sectional survey data (n = 4129). METHODS: In total, 900 vulnerable young people were compared with 3229 non-vulnerable young people. Differences between the two groups were assessed using Chi-squared tests, and associations with possible protective factors were assessed using logistic regression (adjusting for confounding factors). RESULTS: Vulnerable young people have a higher prevalence of smoking tobacco (15% vs 9%, P < 0.001), using cannabis (7% vs 5%, P = 0.03) and self-harming (16% vs 9%, P < 0.001) monthly or more compared with the rest of the Wiltshire adolescent population. Whilst vulnerable young people have many shared protective factors with non-vulnerable young people, there are also differences between the two groups. CONCLUSIONS: There are shared protective factors across HRB that can build on the resilience of a young person, impacting their current and future health. Therefore, we should focus our attention on developing protective factors that promote health and well-being, not solely delivering specialist interventions targeted at specific risks. Further consideration should be given to identifying and promoting protective factors specifically for vulnerable people as they have higher levels of HRB and experience protective factors differently.


Asunto(s)
Disparidades en el Estado de Salud , Asunción de Riesgos , Adolescente , Niño , Estudios Transversales , Femenino , Humanos , Masculino , Prevalencia , Factores Protectores , Encuestas y Cuestionarios , Reino Unido/epidemiología , Poblaciones Vulnerables/psicología , Poblaciones Vulnerables/estadística & datos numéricos
7.
Phys Rev Lett ; 121(20): 203401, 2018 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-30500226

RESUMEN

Using classical arguments Wannier [Phys. Rev. 90, 817 (1953)PHRVAO0031-899X10.1103/PhysRev.90.817] proposed an electron-impact ionization cross section for neutral atoms to behave as E^{1.127}, where E is the excess energy above threshold. Using similar arguments Klar [J. Phys. B 14, 4165 (1981)JPAMA40022-370010.1088/0022-3700/14/21/027] obtained E^{2.65} to be the corresponding threshold law for positron impact. Recently, Babij et al. [Phys. Rev. Lett. 120, 113401 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.113401] measured near-threshold positron-impact breakup behavior to be similar to that expected for electrons. Using the convergent close-coupling method for the atomic hydrogen target, we examine cross sections at near-threshold energies for electron and positron impact. Contrary to the experiment, the calculated cross sections are found to behave differently for the two projectiles and consistently with the aforementioned threshold laws, despite the entirely quantum nature of these problems. For electron impact, the threshold behavior holds while the total electron spin asymmetry remains constant, whereas for positron scattering the threshold law holds for breakup while the positronium-formation component of the ionization cross section remains constant.

8.
Public Health ; 160: 62-69, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29751223

RESUMEN

OBJECTIVES: This article aims to describe the public health career experiences of international graduates of a Master of Science in Public Health (MSc PH) programme and to contribute to developing the evidence base on international public health workforce capacity development. STUDY DESIGN: A sequential mixed methods study was conducted between January 2017 and April 2017. METHODS: Ninety-seven international graduates of one UK university's MSc PH programme were invited to take part in an online survey followed by semistructured interviews, for respondents who consented to be interviewed. We computed the descriptive statistics of the quantitative data obtained, and qualitative data were thematically analysed. RESULTS: The response rate was 48.5%. Most respondents (63%) were employed by various agencies within 1 year after graduation. Others (15%) were at different stages of doctor of philosophy studies. Respondents reported enhanced roles after graduation in areas such as public health policy analysis (74%); planning, implementation and evaluation of public health interventions (74%); leadership roles (72%); and research (70%). The common perceived skills that were relevant to the respondents' present jobs were critical analysis (87%), multidisciplinary thinking (86%), demonstrating public health leadership skills (84%) and research (77%). Almost all respondents (90%) were confident in conducting research. Respondents recommended the provision of longer public health placement opportunities, elective courses on project management and advanced statistics, and 'internationalisation' of the programme's curriculum. CONCLUSIONS: The study has revealed the relevance of higher education in public health in developing the career prospects and skills of graduates. International graduates of this MSc PH programme were satisfied with the relevance and impact of the skills they acquired during their studies. The outcomes of this study can be used for curriculum reformation. Employers' perspectives of the capabilities of these graduates, however, need further consideration.


Asunto(s)
Movilidad Laboral , Educación de Postgrado , Empleo/estadística & datos numéricos , Personal Profesional Extranjero/psicología , Salud Pública/educación , Adulto , Curriculum , Femenino , Personal Profesional Extranjero/estadística & datos numéricos , Humanos , Masculino , Persona de Mediana Edad , Evaluación de Programas y Proyectos de Salud , Investigación Cualitativa , Autoeficacia , Encuestas y Cuestionarios , Reino Unido , Adulto Joven
9.
Phys Rev Lett ; 114(18): 183201, 2015 May 08.
Artículo en Inglés | MEDLINE | ID: mdl-26000999

RESUMEN

Utilizing the two-center convergent close-coupling method, we find a several order of magnitude enhancement in the formation of antihydrogen via antiproton scattering with positronium in an excited state over the ground state. The effect is greatest at the lowest energies considered, which encompass those achievable in experiment. This suggests a practical approach to creating neutral antimatter for testing its interaction with gravity and for spectroscopic measurements.

10.
Diabetologia ; 56(8): 1743-51, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23674172

RESUMEN

AIMS/HYPOTHESIS: HNF1A-MODY is a monogenic form of diabetes caused by mutations in the HNF1A gene. Here we identify, for the first time, HNF1A-MODY-associated microRNAs (miRNAs) that can be detected in the serum of HNF1A-MODY carriers. METHODS: An miRNA array was carried out in rat INS-1 insulinoma cells inducibly expressing the common human Pro291fsinsC-HNF1A frame shift mutation. Differentially expressed miRNAs were validated by quantitative real-time PCR. Expression of miRNAs in the serum of HNF1A-MODY carriers (n = 31), MODY-negative family members (n = 10) and individuals with type 2 diabetes mellitus (n = 17) was quantified by absolute real-time PCR analysis. RESULTS: Inducible expression of Pro291fsinsC-HNF1A in INS-1 cells caused a significant upregulation of three miRNAs (miR-103, miR-224, miR-292-3p). The differential expression of two miRNAs (miR-103 and miR-224) was validated in vitro. Strongly elevated levels of miR-103 and miR-224 could be detected in the serum of HNF1A-MODY carriers compared with MODY-negative family controls. Serum levels of miR-103 distinguished HNF1A-MODY carriers from HbA1c-matched individuals with type 2 diabetes mellitus. CONCLUSIONS/INTERPRETATION: Our study demonstrates that the pathophysiology of HNF1A-MODY is associated with the overexpression of miR-103 and miR-224. Furthermore, our study demonstrates that these miRNAs can be readily detected in the serum of HNF1A-MODY carriers.


Asunto(s)
Diabetes Mellitus Tipo 2/genética , Factor Nuclear 1-alfa del Hepatocito/genética , MicroARNs/genética , Animales , Mutación del Sistema de Lectura/genética , Insulinoma/genética , Ratas , Reacción en Cadena en Tiempo Real de la Polimerasa , Factor 1 de Transcripción de Linfocitos T/genética
11.
Phys Rev Lett ; 110(8): 083001, 2013 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-23473139

RESUMEN

The double photoionization of Mg has been studied experimentally and theoretically in a kinematic where the two photoelectrons equally share the excess energy. The observation of a symmetrized gerade amplitude, which strongly deviates from the Gaussian ansatz, is explained by a two-electron interference predicted theoretically, but never before observed experimentally. Similar to the Cooper minima in the single photoionization cross section, the effect finds its origin in the radial extent and oscillation of the target wave function.

12.
Phys Rev Lett ; 111(17): 173201, 2013 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-24206488

RESUMEN

Theoretical confirmation of the experimentally observed phenomenon [Knudsen et al., Phys. Rev. Lett. 105, 213201 (2010)] of target structure-induced suppression of the ionization cross section for low-energy antiproton-molecular hydrogen collisions is given. To this end a novel time-dependent convergent close-coupling approach to the scattering problem that accounts for all possible orientations of the molecular target, has been developed. The approach is applied to study single ionization of molecular hydrogen on the wide energy range from 1 keV to 2 MeV with a particular emphasis on low energies. Results for the orientation-averaged total single ionization cross section are compared with available experimental data and good agreement is found at low (<20 keV) and high (>90 keV) energies. A minor discrepancy is found within a small energy gap near the maximum of the cross section.

13.
Phys Rev Lett ; 111(1): 013003, 2013 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-23862999

RESUMEN

We investigate the single-photon double ionization of helium at photon energies of 440 and 800 eV. We observe doubly charged ions with close to zero momentum corresponding to electrons emitted back to back with equal energy. These slow ions are the unique fingerprint of an elusive quasifree photon double ionization mechanism predicted by Amusia et al. nearly four decades ago [J. Phys. B 8, 1248 (1975)]. It results from the nondipole part of the electromagnetic interaction. Our experimental data are supported by calculations performed using the convergent close-coupling and time-dependent close-coupling methods.

14.
Br J Cancer ; 107(6): 967-76, 2012 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-22892391

RESUMEN

BACKGROUND: Neuroblastoma remains a major cause of cancer-linked mortality in children. miR-204 has been used in microRNA expression signatures predictive of neuroblastoma patient survival. The aim of this study was to explore the independent association of miR-204 with survival in a neuroblastoma cohort, and to investigate the phenotypic effects mediated by miR-204 expression in neuroblastoma. METHODS: Neuroblastoma cell lines were transiently transfected with miR-204 mimics and assessed for cell viability using MTS assays. Apoptosis levels in cell lines were evaluated by FACS analysis of Annexin V-/propidium iodide-stained cells transfected with miR-204 mimics and treated with chemotherapy drug or vehicle control. Potential targets of miR-204 were validated using luciferase reporter assays. RESULTS: miR-204 expression in primary neuroblastoma tumours was predictive of patient event-free and overall survival, independent of established known risk factors. Ectopic miR-204 expression significantly increased sensitivity to cisplatin and etoposide in vitro. miR-204 direct targeting of the 3' UTR of BCL2 and NTRK2 (TrkB) was confirmed. CONCLUSION: miR-204 is a novel predictor of outcome in neuroblastoma, functioning, at least in part, through increasing sensitivity to cisplatin by direct targeting and downregulation of anti-apoptotic BCL2. miR-204 also targets full-length NTRK2, a potent oncogene involved with chemotherapy drug resistance in neuroblastoma.


Asunto(s)
Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Cisplatino/farmacología , Resistencia a Antineoplásicos , MicroARNs/farmacología , Neuroblastoma/tratamiento farmacológico , Neuroblastoma/genética , Proteínas Proto-Oncogénicas/efectos de los fármacos , Receptor trkB/efectos de los fármacos , Análisis de Varianza , Animales , Apoptosis/genética , Línea Celular Tumoral , Supervivencia Celular/genética , Modelos Animales de Enfermedad , Supervivencia sin Enfermedad , Regulación hacia Abajo/efectos de los fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Etopósido/farmacología , Regulación Neoplásica de la Expresión Génica , Humanos , Estimación de Kaplan-Meier , Glicoproteínas de Membrana/efectos de los fármacos , Glicoproteínas de Membrana/metabolismo , Ratones , Ratones Endogámicos , Ratones SCID , Neuroblastoma/mortalidad , Valor Predictivo de las Pruebas , Modelos de Riesgos Proporcionales , Proteínas Tirosina Quinasas/efectos de los fármacos , Proteínas Tirosina Quinasas/genética , Proteínas Tirosina Quinasas/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2 , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptor trkB/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia Arriba
15.
Acta Biomater ; 70: 84-97, 2018 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-29447961

RESUMEN

3D scaffold-based in vitro cell culturing is a recent technological advancement in cancer research bridging the gap between conventional 2D culture and in vivo tumours. The main challenge in treating neuroblastoma, a paediatric cancer of the sympathetic nervous system, is to combat tumour metastasis and resistance to multiple chemotherapeutic drugs. The aim of this study was to establish a physiologically relevant 3D neuroblastoma tissue-engineered system and explore its therapeutic relevance. Two neuroblastoma cell lines, chemotherapeutic sensitive Kelly and chemotherapeutic resistant KellyCis83 were cultured in a 3D in vitro model on two collagen-based scaffolds containing either glycosaminoglycan (Coll-GAG) or nanohydroxyapatite (Coll-nHA) and compared to 2D cell culture and an orthotopic murine model. Both neuroblastoma cell lines actively infiltrated the scaffolds and proliferated displaying >100-fold increased resistance to cisplatin treatment when compared to 2D cultures, exhibiting chemosensitivity similar to orthotopic xenograft in vivo models. This model demonstrated its applicability to validate miRNA-based gene delivery. The efficacy of liposomes bearing miRNA mimics uptake and gene knockdown was similar in both 2D and 3D in vitro culturing models highlighting the proof-of-principle for the applicability of 3D collagen-based scaffolds cell system for validation of miRNA function. Collectively, this data shows the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. While neuroblastoma is the specific disease being focused upon, the platform may have multi-functionality beyond this tumour type. STATEMENT OF SIGNIFICANCE: Traditional 2D cell cultures do not completely capture the 3D architecture of cells and extracellular matrix contributing to a gap in our understanding of mammalian biology at the tissue level and may explain some of the discrepancies between in vitro and in vivo results. Here, we demonstrated the successful development and characterisation of a physiologically relevant, scaffold-based 3D tissue-engineered neuroblastoma cell model, strongly supporting its value in the evaluation of chemotherapeutics, targeted therapies and investigation of neuroblastoma pathogenesis. The ability to test drugs in this reproducible and controllable tissue-engineered model system will help reduce the attrition rate of the drug development process and lead to more effective and tailored therapies. Importantly, such 3D cell models help to reduce and replace animals for pre-clinical research addressing the principles of the 3Rs.


Asunto(s)
Colágeno/química , Técnicas de Transferencia de Gen , Neuroblastoma , Andamios del Tejido/química , Ensayos Antitumor por Modelo de Xenoinjerto , Animales , Línea Celular Tumoral , Femenino , Xenoinjertos , Humanos , Ratones , Ratones Desnudos , Neuroblastoma/genética , Neuroblastoma/metabolismo , Neuroblastoma/patología , Neuroblastoma/terapia
16.
Intern Med J ; 37(9): 614-9, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17543004

RESUMEN

BACKGROUND: Studies have shown an association between electromagnetic fields and childhood leukaemia. The aim of this study was to determine whether there is an increased risk of lymphoproliferative disorders (LPD) or myeloproliferative disorders (MPD) associated with residence < or =300 m from high-voltage power lines. METHODS: Case-control study of 854 patients diagnosed with LPD or MPD (including leukaemia, lymphoma and related conditions) aged 0-94 years comprising all cases diagnosed in Tasmania between 1972 and 1980. Controls were individually matched for sex and approximate age at the time of diagnosis. RESULTS: Compared with those who had always lived >300 m from a power line, those who had ever lived within 50 m had an odds ratio (OR) of 2.06 (95% confidence interval 0.87-4.91) for developing LPD or MPD (based on 768 adult case-control pairs); those who had lived between 50 and 300 m had an OR of 1.30 (0.88-1.91). Adults who had lived within 300 m of a power line during the first 15 years of life had a threefold increase in risk (OR 3.23; 1.26-8.29); those who had lived within the same distance aged 0-5 years had a fivefold increase in risk (OR 4.74; 0.98-22.9). These associations were strengthened when analyses were repeated for 201 pairs with entirely Tasmanian residential histories. CONCLUSION: Although recognizing that this study has limitations, the results raise the possibility that prolonged residence close to high-voltage power lines, especially early in life, may increase the risk of the development of MPD and LPD later.


Asunto(s)
Suministros de Energía Eléctrica/efectos adversos , Campos Electromagnéticos/efectos adversos , Exposición a Riesgos Ambientales/efectos adversos , Trastornos Linfoproliferativos/epidemiología , Trastornos Mieloproliferativos/epidemiología , Adolescente , Adulto , Estudios de Casos y Controles , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Trastornos Linfoproliferativos/etiología , Trastornos Mieloproliferativos/etiología , Factores de Riesgo , Tasmania/epidemiología , Factores de Tiempo
17.
J R Army Med Corps ; 153(4): 244-50, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18619157

RESUMEN

AIM: To determine the number, status and nature of emergency department attendances to deployed field hospitals. POPULATION: All attendances to the emergency department (ED) of deployed field hospitals in support of Operation TELIC (Iraq) from initial entry war fighting to enduring operations. METHODS: Analysis of hand written and electronic registers ED attendance registers and validation with four other data sources. RESULTS: Validation of data held on OpEDAR against 4 other data sources shows that OpEDAR is accurate, but that accuracy can be further improved. 26,746 ED attendances recorded on OP TELIC from 19 March 2003 to 11 November 2006. 21,112 (78.9%) were UK military. Overall, 43.5% were admitted from ED. Attendances peaked during TELIC phases 2 (422.9 per 1,000 troops deployed), but have settled to around 200 per 1,000 troops deployed in the more recent phases. Ophthalmology rates peaked in TELIC 2 to 20.72 per 1,000 and have since reduced to a consistent 10 to 15 per 1,000. This suggests that preventative measures introduced for eye injury are incompletely effective or incompletely utilised. CONCLUSIONS: OpEDAR is a clinical tool to inform manning, equipment and training requirements for enduring and new operations, focused on the requirements of the emergency department. Multivariate quality control models applied in industry could be applied to OpEDAR to produce a dynamic epidemiological tool that identifies emerging case clusters and facilitates deployed commanders to take preventative action.


Asunto(s)
Servicios Médicos de Urgencia/estadística & datos numéricos , Métodos Epidemiológicos , Hospitales Militares/estadística & datos numéricos , Medicina Militar , Personal Militar , Unidades Móviles de Salud/estadística & datos numéricos , Recolección de Datos , Bases de Datos como Asunto , Humanos , Irak , Sistema de Registros , Reino Unido
18.
Nat Commun ; 8(1): 1544, 2017 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-29146898

RESUMEN

The interaction of antiprotons with low-energy positronium atoms is a fundamental three-body problem whose significance is its utility for formation of antihydrogen. Particular importance resides in understanding processes involving excited positronium states. Until recently such studies were performed using classical techniques. However, they become inapplicable in the low-energy domain. Here we report the results of comprehensive quantum calculations, which include initial excited positronium states with principal quantum numbers up to n i = 5. Contrary to expectation from earlier work, there are only muted increases in the cross-sections for antihydrogen formation for n i > 3. We interpret this in terms of quantum suppression of the reaction at higher angular momenta. Furthermore, the cross-sections for elastic scattering are around two orders of magnitude higher, which we attribute to the degeneracy of the positronium states. We outline some experimental consequences of our results.

19.
Phys Med ; 32(12): 1827-1832, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-27742255

RESUMEN

Stopping powers of H, He, H2, and H2O targets for antiprotons have been calculated using a convergent close-coupling method. For He and H2 targets electron-electron correlations are fully accounted for using a multiconfiguration approximation. Two-electron processes are included using an independent-event model. The water molecule is described using a neon-like structure model with a pseudo-spherical potential. Results are tabulated for the purpose of Monte Carlo simulations to model antiproton transport through matter for radiation therapy.


Asunto(s)
Método de Montecarlo , Protones , Radioterapia , Electrones , Helio , Hidrógeno , Factores de Tiempo , Agua
20.
Cancer Epidemiol Biomarkers Prev ; 9(9): 895-903, 2000 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-11008906

RESUMEN

Traditional methods of adjustment for multiple comparisons (e.g., Bonferroni adjustments) have fallen into disuse in epidemiological studies. However, alternative kinds of adjustment for data with multiple comparisons may sometimes be advisable. When a large number of comparisons are made, and when there is a high cost to investigating false positive leads, empirical or semi-Bayes adjustments may help in the selection of the most promising leads. Here we offer an example of such adjustments in a large surveillance data set of occupation and cancer in Nordic countries, in which we used empirical Bayes (EB) adjustments to evaluate standardized incidence ratios (SIRs) for cancer and occupation among craftsmen and laborers. For men, there were 642 SIRs, of which 138 (21%) had a P < 0.05 (13% positive with SIR > 1.0 and 8% negative with SIR < or = 1.0) when testing the null hypothesis of no cancer/occupation association; some of these were probably due to confounding by nonoccupational risk factors (e.g., smoking). After EB adjustments, there were 95 (15%) SIRs with P < 0.05 (10% positive and 5% negative). For women, there were 373 SIRs, of which 37 (10%) had P < 0.05 before adjustment (6% positive and 4% negative) and 13 (3%) had P < 0.05 after adjustment (2% positive and 1% negative). Several known associations were confirmed after EB adjustment (e.g., pleural cancer among plumbers, original SIR 3.2 (95% confidence interval, 2.5-4.1), adjusted SIR 2.0 (95% confidence interval, 1.6-2.4). EB can produce more accurate estimates of relative risk by shrinking imprecise outliers toward the mean, which may reduce the number of false positives otherwise flagged for further investigation. For example, liver cancer among chimney sweepers was reduced from an original SIR of 2.2 (range, 1.1-4.4) to an adjusted SIR of 1.1 (range, 0.9-1.4). A potentially important future application for EB is studies of gene-environment-disease interactions, in which hundreds of polymorphisms may be evaluated with dozens of environmental risk factors in large cohort studies, producing thousands of associations.


Asunto(s)
Teorema de Bayes , Neoplasias/epidemiología , Exposición Profesional/estadística & datos numéricos , Vigilancia de la Población/métodos , Análisis de Varianza , Carcinógenos , Femenino , Humanos , Incidencia , Masculino , Oportunidad Relativa , Medición de Riesgo , Países Escandinavos y Nórdicos/epidemiología , Clase Social
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