109 research outputs found
Interpreting the dependence of mutation rates on age and time
Mutations can arise from the chance misincorporation of nucleotides during
DNA replication or from DNA lesions that are not repaired correctly. We
introduce a model that relates the source of mutations to their accumulation
with cell divisions, providing a framework for understanding how mutation rates
depend on sex, age and absolute time. We show that the accrual of mutations
should track cell divisions not only when mutations are replicative in origin
but also when they are non-replicative and repaired efficiently. One
implication is that the higher incidence of cancer in rapidly renewing tissues,
an observation ascribed to replication errors, could instead reflect exogenous
or endogenous mutagens. We further find that only mutations that arise from
inefficiently repaired lesions will accrue according to absolute time; thus, in
the absence of selection on mutation rates, the phylogenetic "molecular clock"
should not be expected to run steadily across species.Comment: 5 figures, 2 table
Analysis of post-merger integration of automobile firms
1 online resource (v, 31 p.)Includes abstract and appendix.Includes bibliographical references (p. 27-30).This paper’s objective is to determine whether merger announcements of world automobile companies would influence the stock price of acquired companies and whether the market reaction to merger announcement is good or bad. 24 acquired companies from the OTC market and 10 acquired companies come from the NYSE market are randomly chosen for this study. The time period is chosen from 1998 to 2012.The DJ (USA) index is used as market return in this paper.
The Market Return Model, the Average Abnormal Return Model and the Capital Asset Pricing Model (CAPM) will be used in this paper. In summary, this study is going to prove whether the merged world automobile firms would gain or loss after merger announcement
DUA-DA: Distillation-based Unbiased Alignment for Domain Adaptive Object Detection
Though feature-alignment based Domain Adaptive Object Detection (DAOD) have
achieved remarkable progress, they ignore the source bias issue, i.e. the
aligned features are more favorable towards the source domain, leading to a
sub-optimal adaptation. Furthermore, the presence of domain shift between the
source and target domains exacerbates the problem of inconsistent
classification and localization in general detection pipelines. To overcome
these challenges, we propose a novel Distillation-based Unbiased Alignment
(DUA) framework for DAOD, which can distill the source features towards a more
balanced position via a pre-trained teacher model during the training process,
alleviating the problem of source bias effectively. In addition, we design a
Target-Relevant Object Localization Network (TROLN), which can mine
target-related knowledge to produce two classification-free metrics (IoU and
centerness). Accordingly, we implement a Domain-aware Consistency Enhancing
(DCE) strategy that utilizes these two metrics to further refine classification
confidences, achieving a harmonization between classification and localization
in cross-domain scenarios. Extensive experiments have been conducted to
manifest the effectiveness of this method, which consistently improves the
strong baseline by large margins, outperforming existing alignment-based works.Comment: 10pages,5 figure
Distribution and Determinants of Correlation between PM2.5 and O3 in China Mainland: Dynamitic simil-Hu Lines
In recent years, China has made great efforts to control air pollution.
During the governance process, it is found that fine particulate matter (PM2.5)
and ozone (O3) change in the same trend among some areas and the opposite in
others, which brings some difficulties to take measures in a planned way.
Therefore, this study adopted multi-year and large-scale air quality data to
explore the distribution of correlation between PM2.5 and O3, and proposed a
concept called dynamic similar hu lines to replace the single fixed division in
the previous research. Furthermore, this study discussed the causes of
distribution patterns quantitatively with geographical detector and random
forest. The causes included natural factors and anthropogenic factors. And
these factors could be divided into three parts according to the
characteristics of spatial distribution: broadly changing with longitude,
changing with latitude, and having local characteristics. Overall, regions with
relatively more densely population, higher GDP, lower altitude, higher
humidity, higher atmospheric pressure, higher surface temperature, less
sunshine hours and more accumulated precipitation often corresponds to positive
correlation coefficient between PM2.5 and O3, no matter in which season. The
parts with opposite conditions that mentioned above are essentially negative
correlation coefficient. And what's more, humidity, global surface temperature,
air temperature and accumulated precipitation are four decisive factors to form
the distribution of correlation between PM2.5 and O3. In general, collaborative
governance of atmospheric pollutants should consider particular time and space
background and also be based on the local actual socio-economic situations,
geography and geomorphology, climate and meteorology and other comprehensive
factors.Comment: Our research group have decided to withdraw this preprin
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