20 research outputs found
Revisiting the phenomenology on the QCD color dipole picture
Using the QCD dipole picture of the hard BFKL Pomeron, we perform a 3
parameter fit analysis of the recent inclusive structure function experimental
measurements at small- and intermediate . As a byproduct, the
longitudinal structure function and the gluon distribution are predicted
without further adjustments. The data description is quite reasonable, being
timely a further study using resummed NLO BFKL kernels along the lines of
recent theoretical developments.Comment: Contribution to the ``International Workshop on Diffraction in
High-Energy Physics'' (DIFFRACTION 2004), Cala Gonone (Sardinia, Italy),
18-23 September 2004; 3 pages, LaTeX fil
On a two Pomeron description of the F_2 structure function
We perform a global fit to the inclusive structure function considering a QCD
inspired model describing the ep scattering. In lines of a two Pomeron
approach, the structure function F_2 has a hard piece given by the model and
the remaining soft contributions: the soft Pomeron and non-singlet content. We
have investigated several choices for the soft Pomeron and its implication in
the data description. In particular, we carefully estimated the relative role
of the hard and the soft contributions in a large span of x and Q^2.Comment: 14 pages, 3 figures. To be published in Eur. Phys. J.
Parametrization of prompt neutron yields from photofission fragments of actinide nuclei for the giant dipole resonance energy range
The dependence of prompt neutron yield on fragment mass ν(A) of photofission of actinide nuclei ²³²Th, ²³⁵U and ²³⁸U in the giant dipole resonance energy range has been parameterized. This allows us to describe the observed changes of saw-tooth behavior of neutron yield from the light and heavy fragments using few energy and nucleon composition dependent free parameters and to predict ν(A) for Pu isotopes.Выполнена параметризация зависимости выходов мгновенных нейтронов от массы осколков ν(A) фотоделения актинидных ядер ²³²Th, ²³⁵U и ²³⁸U для области энергий гигантского дипольного резонанса. Это позволяет описать наблюдаемые изменения пилообразного поведения выхода нейтронов из легкого и тяжелого осколков небольшим числом свободных параметров в зависимости от энергии и нуклонного состава и предсказать ν(A) для изотопов Pu .Виконана параметризацiя залежностi виходiв миттєвих нейтронiв вiд маси уламкiв ν(A) фотоподiлу актинiдних ядер ²³²Th, ²³⁵U і ²³⁸U для областi енергiй гiгантського дипольного резонансу. Це дозволяє описати спостережуванi змiни пилкоподiбної поведiнки виходiв нейтронiв з легкого i важкого уламкiв невеликим числом вiльних параметрiв у залежностi вiд енергiї та нуклонного складу, а також передбачити ν(A) для iзотопiв Pu
Product yields for the photofission of ²³⁹Pu with bremsstrahlung at 17.5 MeV boundary energy
The values of relative cumulative yields of 12 products (⁸⁵mKr, ⁹¹mY, ⁹²Sr, 97Zr, ⁹⁹Mo, ¹⁰⁵Ru, ¹³³I, ¹³⁴I, ¹³⁵I, ¹³⁸Cs, ¹³⁹Ba, ¹⁴²La, ¹⁴³Ce) of the ²³⁹Pu photofission was measured at a maximum bremsstrahlung energy of 17.5 MeV (average excitation energy ~ 12.03 MeV). ²³⁹Pu photofission reaction was stimulated on the electron accelerator of the Institute of Electron Physics NAS of Ukraine – M-30 microtron to simulate the spectra of bremsstrahlung’s photons, secondary electrons, and photoneutrons that hit the ²³⁹Pu target, the GEANT4 code was used. The input of accompanying nuclear reactions to the yield of ²³⁹Pu photofission products for the given experimental parameters was also evaluating. The obtained experimental data of the yields of products ²³⁹Pu photofission were compared with the program codes GEF and Talys1.9.5 simulations.Значення 12-ти відносних кумулятивних виходів продуктів (⁸⁵mKr, ⁹¹mY, ⁹²Sr, 97Zr, ⁹⁹Mo, ¹⁰⁵Ru, ¹³³I, ¹³⁴I, ¹³⁵I, ¹³⁸Cs, ¹³⁹Ba, ¹⁴²La, ¹⁴³Ce) фотоподілу ²³⁹Pu були виміряні при максимальній енергії гальмівного випромінювання 17,5 МеВ (середня енергія збудження ~ 12,03 МеВ). Стимуляція реакції фотоподілу ²³⁹Pu проводилася на прискорювачі електронів Інституту електронної фізики НАН України – мікротроні М-30. Для моделювання спектрів гальмівних фотонів, вторинних електронів і фотонейтронів, що попадали на мішень ²³⁹Pu, використовувався код GEANT4. Було проведено оцінку внеску супутніх ядерних реакцій у виходи продуктів фотоподілу ²³⁹Pu при заданих параметрах експерименту. Отримані експериментальні дані по виходах продуктів фотоподілу ²³⁹Pu порівнювалися з результатами симуляції кодами GEF і Talys1.9.5Значения 12-ти относительных кумулятивных выходов продуктов (⁸⁵mKr, ⁹¹mY, ⁹²Sr, 97Zr, ⁹⁹Mo, ¹⁰⁵Ru, ¹³³I, ¹³⁴I, ¹³⁵I, ¹³⁸Cs, ¹³⁹Ba, ¹⁴²La, ¹⁴³Ce) фотоделения ²³⁹Pu были измерены при максимальной энергии тормозного излучения 17,5 МэВ (средняя энергия возбуждения ~ 12,03 МэВ). Стимуляция реакции фотоделения ²³⁹Pu проводилась на ускорителе электронов Института электронной физики НАН Украины – микротроне М-30. Для моделирования спектров тормозных фотонов, вторичных электронов и фотонейтронов, попадающих на мишень ²³⁹Pu, использовался код GEANT4. Проведена оценка вклада сопутствующих ядерных реакций в выходы продуктов фотоделения ²³⁹Pu при заданных параметрах эксперимента. Полученные экспериментальные данные по выходам продуктов фотоделения ²³⁹Pu сравнивались с результатами симуляции кодами GEF и Talys1.9.5
Isotopic identification of photofissed nuclear materials in stainless steel containers using delayed gamma-rays
The results of isotope identification of nuclear materials (²³²Th, ²³⁵U, ²³⁸U, ²³⁹Pu) packed in hermetic stainless steel containers by their stimulated delayed gamma radiation are presented. The ratios of the values of the time dependences of the intensity of gamma radiation of the light and heavy product of their photofission were used for the analysis. Gamma radiation from photofission products ⁸⁹Rb (1031.9; 1248.1 keV) and ¹³⁸Cs (1009.8; 1436.8; 2218.0; 2639.6 keV) was used to differentiate nuclear materials. The photofission reaction the samples of nuclear materials was stimulated on an electron accelerator, an M-30 microtron, at maximum bremsstrahlung energy of 12.5 MeV. The possibility of carrying out isotopic identification of nuclear materials using 8 ratios of the yields of first members of decay chain of ⁸⁹Rb light fission product to correspondence values of ¹³⁸Cs heavy fission product has been demonstrated.Представлено результати ізотопної ідентифікації ядерних матеріалів (²³²Th, ²³⁵U, ²³⁸U, ²³⁹Pu), упакованих у герметичні контейнери з нержавіючої сталі, за їх стимульованим затриманим гамма-випромінюванням. Для аналізу використовувалося відношення значень часових залежностей інтенсивності гамма-випромінювання від легкого та важкого продуктів їхнього фотоподілу. Гамма-випромінювання продуктів фотоподілу ⁸⁹Rb (1031,9; 1248,1 кеВ) та ¹³⁸Cs (1009,8; 1436,8; 2218,0; 2639,6 кеВ) використовувалися для диференціації ядерних матеріалів. Стимуляція реакції фотоподілу зразків проводилася на електронному прискорювачі – мікротроні М-30 з максимальної енергії гальмівного випромінювання 12,5 МеВ. Продемонстровано можливість проведення ізотопної ідентифікації ядерних матеріалів за 8 відношеннями виходів перших членів ланцюжка легкого продукту ⁸⁹Rb до окремих значень важкого продукту ¹³⁸Cs
Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration
Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice
A multi‐omics approach identifies key regulatory pathways induced by long‐term zinc supplementation in human primary retinal pigment epithelium
In age-related macular degeneration (AMD), both systemic and local zinc levels decline.
Elevation of zinc in clinical studies delayed the progression to end-stage AMD. However, the molecular
pathways underpinning this beneficial effect are not yet identified. In this study, we used differentiated
primary human fetal retinal pigment epithelium (RPE) cultures and long-term zinc supplementation
to carry out a combined transcriptome, proteome and secretome analysis from three genetically
different human donors. After combining significant differences, we identified the complex molecular
networks using Database for Annotation, Visualization and Integrated Discovery (DAVID) and
Ingenuity Pathway Analysis (IPA). The cell cultures from the three donors showed extensive
pigmentation, development of microvilli and basal infoldings and responded to zinc supplementation
with an increase in transepithelial electrical resistance (TEER) (apical supplementation: 443.2 ± 79.3%,
basal supplementation: 424.9 ± 116.8%, compared to control: 317.5 ± 98.2%). Significant changes were
observed in the expression of 1044 genes, 151 cellular proteins and 124 secreted proteins. Gene set
enrichment analysis revealed changes in specific molecular pathways related to cell adhesion/polarity,
extracellular matrix organization, protein processing/transport, and oxidative stress response by zinc
and identified a key upstream regulator effect similar to that of TGFB1
Prevalence of Age-Related Macular Degeneration in Europe: The Past and the Future
Purpose Age-related macular degeneration (AMD) is a frequent, complex disorder in elderly of European ancestry. Risk profiles and treatment options have changed considerably over the years, which may have affected disease prevalence and outcome. We determined the prevalence of early and late AMD in Europe from 1990 to 2013 using the European Eye Epidemiology (E3) consortium, and made projections for the future. Design Meta-analysis of prevalence data. Participants A total of 42 080 individuals 40 years of age and older participating in 14 population-based cohorts from 10 countries in Europe. Methods AMD was diagnosed based on fundus photographs using the Rotterdam Classification. Prevalence of early and late AMD was calculated using random-effects meta-analysis stratified for age, birth cohort, gender, geographic region, and time period of the study. Best-corrected visual acuity (BCVA) was compared between late AMD subtypes; geographic atrophy (GA) and choroidal neovascularization (CNV). Main Outcome Measures Prevalence of early and late AMD, BCVA, and number of AMD cases. Results Prevalence of early AMD increased from 3.5% (95% confidence interval [CI] 2.1%–5.0%) in those aged 55–59 years to 17.6% (95%