62 research outputs found
Inclusive meson production in peripheral collisions of ultrarelativistic heavy ions
There exist several proposals to use Weizs\"{a}cker-Williams photons
generated by ultrarelativistic heavy ions to produce exotic particles in
fusion reactions. To estimate the background conditions for such
reactions we analyze various mechanisms of meson production in very peripheral
collisions of ultrarelativistic heavy ions at RHIC and LHC energies. Besides
fusion they include also electromagnetic interactions
and strong nucleon-nucleon interactions in grazing collisions. All these
processes are characterised by low multiplicities of produced particles.
and events are simulated by corresponding Monte Carlo codes,
RELDIS and FRITIOF. In each of these processes a certain fraction of pions is
produced close to the mid-rapidity region that gives a background for the
events. The possibility of selecting mesons produced in
fusion events via different cut procedures is
demonstrated.Comment: 27 pages with 4 eps-figures included, uses axodraw.sty Tab.2 and 3
correcte
Vortex dynamics and states of artificially layered superconducting films with correlated defects
Linear resistances and -characteristics have been measured over a wide
range in the parameter space of the mixed phase of multilayered a-TaGe/Ge
films. Three films with varying interlayer coupling and correlated defects
oriented at an angle from the film normal were investigated.
Experimental data were analyzed within vortex glass models and a second order
phase transition from a resistive vortex liquid to a pinned glass phase.
Various vortex phases including changes from three to two dimensional behavior
depending on anisotropy have been identified. Careful analysis of
-characteristics in the glass phases revealed a distinctive and
-dependence of the glass exponent . The vortex dynamics in the
Bose-glass phase does not follow the predicted behavior for excitations of
vortex kinks or loops.Comment: 16 pages, 10 figures, 3 table
Time to cancer treatment and reproductive outcomes after fertility preservation among adolescent and young adult women with cancer
Background: Fertility preservation (FP) may be underused after cancer diagnosis because of uncertainty around delays to cancer treatment and subsequent reproductive success. Methods: Women aged 15 to 39 years diagnosed with cancer between 2004 and 2015 were identified from the North Carolina Central Cancer Registry. Use of assisted reproductive technology (ART) after cancer diagnosis between 2004 and 2018 (including FP) was assessed through linkage to the Society for Assisted Reproductive Technology. Linear regression was used to examine time to cancer treatment among women who did (n = 95) or did not (n = 469) use FP. Modified Poisson regression was used to estimate risk ratios (RRs) and 95% CIs for pregnancy and birth based on timing of ART initiation relative to cancer treatment (n = 18 initiated before treatment for FP vs n = 26 initiated after treatment without FP). Results: The median time to cancer treatment was 9 to 33 days longer among women who used FP compared with women who did not, matched on clinical factors. Women who initiated ART before cancer treatment may be more likely to have a live birth given pregnancy compared with women who initiated ART after cancer treatment (age-adjusted RR, 1.47; 95% CI, 0.98-2.23), though this may be affected by the more frequent use of gestational carriers in the former group (47% vs 20% of transfer cycles, respectively). Conclusions: FP delayed gonadotoxic cancer treatment by up to 4.5 weeks, a delay that would not be expected to alter prognosis for many women. Further study of the use of gestational carriers in cancer populations is warranted to better understand its effect on reproductive outcomes
Strengthening Causal Inference in Exposomics Research: Application of Genetic Data and Methods
Advances in technologies to measure a broad set of exposures have led to a range of exposome research efforts. Yet, these efforts have insufficiently integrated methods that incorporate genetic data to strengthen causal inference, despite evidence that many exposome-associated phenotypes are heritable. OBJECTIVE: We demonstrate how integration of methods and study designs that incorporate genetic data can strengthen causal inference in exposomics research by helping address six challenges: reverse causation and unmeasured confounding, comprehensive examination of phenotypic effects, low efficiency, replication, multilevel data integration, and characterization of tissue-specific effects. Examples are drawn from studies of biomarkers and health behaviors, exposure domains where the causal inference methods we describe are most often applied. DISCUSSION: Technological, computational, and statistical advances in genotyping, imputation, and analysis, combined with broad data sharing and cross-study collaborations, offer multiple opportunities to strengthen causal inference in exposomics research. Full application of these opportunities will require an expanded understanding of genetic variants that predict exposome phenotypes as well as an appreciation that the utility of genetic variants for causal inference will vary by exposure and may depend on large sample sizes. However, several of these challenges can be addressed through international scientific collaborations that prioritize data sharing. Ultimately, we anticipate that efforts to better integrate methods that incorporate genetic data will extend the reach of exposomics research by helping address the challenges of comprehensively measuring the exposome and its health effects across studies, the life course, and in varied contexts and diverse populations
Crescimento e produção de pigmentos fotossintéticos em Achillea millefolium L. cultivada sob diferentes níveis de sombreamento e doses de nitrogênio
NATURAL REGENERATION STRATUM AS AN INDICATOR OF RESTORATION IN AREA OF ENVIRONMENTAL COMPENSATION FOR MINING LIMESTONE, MUNICIPALITY OF BARROSO, MG, BRAZIL
Utilização de métodos estatísticos multivariados na caracterização do mosaico sucessional em floresta semidecídual
Evaluation of the process of reabilitation of a stretch of Riparian forest in Itapemirim river watershed - ES
Este estudo foi realizado em uma área de floresta ciliar em processo de recuperação mediante reabilitação.A área de estudo está localizada na sub-bacia hidrográfica do rio Itapemirim, no Município de Alegre, ES, Brasil.A ocupação e uso do solo antes da revegetação eram de pastagem com Brachiaria sp. A revegetação da áreafoi feita em 1997, com espécies autóctones e alóctones arbóreas, em arranjo de distribuição aleatório, em umaárea de 1,2 ha. Para a realização dos estudos foram feitos inventários florestais nos períodos de 2004/2005e 2005/2006, sendo medidos os indivíduos de hábito arbustivo e arbóreo com circunferência à altura do peito(CAP) > 5 cm e suas alturas totais. As espécies encontradas na área foram identificadas e classificadas de acordocom seus grupos ecológicos, síndromes de dispersão e presença silvestre, sendo calculados os parâmetros florísticos,a estrutura vertical e a dinâmica estrutural desse povoamento. O objetivo do trabalho foi avaliar o desenvolvimentodo povoamento implantado para subsidiar práticas silviculturais quanto à seleção e implantação de espécies pararevegetação de áreas de floresta ciliar degradadas, em condições semelhantes. Os resultados demonstraram quefoi implantado um povoamento florestal com grande diversidade de espécies e a estratificação em classes dealtura foi à semelhança de povoamentos heterogêneos naturais. As espécies identificadas como edificadoras darevegetação da área estudada foram: Anadenanthera colubrina, Caesalpinia leyostachia, Acacia auriculiformis,Acacia mangium, Handroanthus serratifolius, Inga edulis, Joannesia princeps, Pterogyne nitens, Enterelobiumcontortisiliquum, Tabernaemontana hystrix e Anthocephalus indicus. A distribuição em classes de tamanho dacomunidade implantada ocorre em forma de "J" reverso, havendo a predominância de indivíduos pioneiros emtodas as classes de CAP. A dinâmica da estrutura horizontal apontou que, para o sucesso, continuidade e desenvolvimentoda recuperação da área, seja monitorada a regeneração natural em relação à sua presença e à eficiência dos fatoresbióticos e abióticos que nela interferem. A não observância de indivíduos arbustivos e arbóreos regenerados naturalmente,na classe de inclusão do estudo, indica a fragilidade inicial da área rumo à sustentabilidade do sistema.The study was realized in an area of riparian forest in process by means of rehabilitation. Thestudy area is located in Rio Itapemirim, in Alegre city, Brazil. The occupation and use of the soil beforethe recovery were of pasture with Brachiaria sp. The recovery of this area was in 1997, with autochthonousand allochthonous species, in casually distribution arrangement, in an area of 1,2 ha. For this studies wasrealized forest inventories in the periods of 2004/2005 and 2005/2006, being measured the arboreal individualswith circumference at breast height (CBH) and total heights. The species found in the area were identifiedand classified in this ecological groups, dispersion syndromes and wild presence, it forms calculated thefloristic parameters, the vertical structure and the structural dynamics of this plantation. The objective ofthis work went evaluate the development of the plantation implanted to subsidize practical silviculture withrelationship to the selection and plantation of species for the revegetation of degraded areas of riparianforest, in similar conditions. The results of the studies demonstrated that a forest plantation was implantedwith great diversity of species and the bedding in height classes it went to the likeness of natural heterogeneous.The species identified as builders of the plantation of the studied area were: Anadenanthera colubrina, Caesalpinia leyostachia, Acacia auriculiformis, Acacia mangium, Handroanthus serratifolius, Inga edulis, Joannesia princeps,Pterogyne nitens, Enterelobium contortisiliquum, Tabernaemontana hystrix, and Anthocephalus indicus . Theimplanted community's distribution diametric happens in reverse J shape having the pioneer individuals'predominance in all the classes of CBH. The dynamics of the horizontal structure points that for the success,continuity and development of the recovery of the area, the natural regeneration be monitored in relationto its presence and efficiency of the biotic factors and abiotic those interfere in the same. The not tree individualsobservance in natural regeneration, in the class of inclusion of the study, indicate the initial fragility of thearea heading for sustentabilidade of the system
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