74 research outputs found
Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda + l^{+} l^{-} in the Light-cone Sum Rules
Within the Standard Model, we investigate the weak decays of and with the light-cone
sum rules approach. The higher twist distribution amplitudes of
baryon to the leading conformal spin are included in the sum rules for
transition form factors. Our results indicate that the higher twist
distribution amplitudes almost have no influences on the transition form
factors retaining the heavy quark spin symmetry, while such corrections can
result in significant impacts on the form factors breaking the heavy quark spin
symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of
baryon are also employed in the sum rules for a comparison, which can
give rise to the form factors approximately 5 times larger than that in terms
of conformal expansion. Utilizing the form factors calculated in LCSR, we then
perform a careful study on the decay rate, polarization asymmetry and
forward-backward asymmetry, with respect to the decays of , .Comment: 38 pages, 15 figures, some typos are corrected and more references
are adde
Familial thrombocytopenia due to a complex structural variant resulting in a WAC-ANKRD26 fusion transcript
Advances in genome sequencing have resulted in the identification of the causes for numerous rare diseases. However, many cases remain unsolved with standard molecular analyses. We describe a family presenting with a phenotype resembling inherited thrombocytopenia 2 (THC2). THC2 is generally caused by single nucleotide variants that prevent silencing of ANKRD26 expression during hematopoietic differentiation. Short-read whole-exome and genome sequencing approaches were unable to identify a causal variant in this family. Using long-read whole-genome sequencing, a large complex structural variant involving a paired-duplication inversion was identified. Through functional studies, we show that this structural variant results in a pathogenic gain-of-function WAC-ANKRD26 fusion transcript. Our findings illustrate how complex structural variants that may be missed by conventional genome sequencing approaches can cause human disease
Neuro4Neuro: A neural network approach for neural tract segmentation using large-scale population-based diffusion imaging
Subtle changes in white matter (WM) microstructure have been associated with
normal aging and neurodegeneration. To study these associations in more detail,
it is highly important that the WM tracts can be accurately and reproducibly
characterized from brain diffusion MRI. In addition, to enable analysis of WM
tracts in large datasets and in clinical practice it is essential to have
methodology that is fast and easy to apply. This work therefore presents a new
approach for WM tract segmentation: Neuro4Neuro, that is capable of direct
extraction of WM tracts from diffusion tensor images using convolutional neural
network (CNN). This 3D end-to-end method is trained to segment 25 WM tracts in
aging individuals from a large population-based study (N=9752, 1.5T MRI). The
proposed method showed good segmentation performance and high reproducibility,
i.e., a high spatial agreement (Cohen's kappa, k = 0.72 ~ 0.83) and a low
scan-rescan error in tract-specific diffusion measures (e.g., fractional
anisotropy: error = 1% ~ 5%). The reproducibility of the proposed method was
higher than that of a tractography-based segmentation algorithm, while being
orders of magnitude faster (0.5s to segment one tract). In addition, we showed
that the method successfully generalizes to diffusion scans from an external
dementia dataset (N=58, 3T MRI). In two proof-of-principle experiments, we
associated WM microstructure obtained using the proposed method with age in a
normal elderly population, and with disease subtypes in a dementia cohort. In
concordance with the literature, results showed a widespread reduction of
microstructural organization with aging and substantial group-wise
microstructure differences between dementia subtypes. In conclusion, we
presented a highly reproducible and fast method for WM tract segmentation that
has the potential of being used in large-scale studies and clinical practice.Comment: Preprint to be published in NeuroImag
Nonleptonic decays to , and other final states in Factorization
We consider nonleptonic Cabibbo--allowed decays in the
factorization approximation. We calculate nonleptonic decays of the type and relative to
and where we include among the
pseudoscalar states(P) and the vector states(V) the newly discovered
resonances, and . In the ratio of decays to
and relative to the decays to these states,
the poorly known decay constants of and cancel leading
to predictions that can shed light on the nature of these new states. In
general, we predict the decays to be larger than the corresponding
decays and in particular we find the branching ratio for can be between four to five times the branching ratio
for . This enhancement of branching
ratios follows primarily from the fact that more partial waves contribute in
decays than in decays. Our predictions are largely
independent of model calculations of hadronic inputs like form factors and
decay constants.Comment: 16 pages LaTe
Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology
notes: As the primary author, OâMalley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. âMacrobeâ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes â the dominant life form on the planet, both now and throughout evolutionary history â will transform some of the philosophy of biologyâs standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology â including biofilm formation, chemotaxis, quorum sensing and gene transfer â that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations
Integrated analysis of environmental and genetic influences on cord blood DNA methylation in new-borns
Epigenetic processes, including DNA methylation (DNAm), are among the mechanisms allowing integration of genetic and environmental factors to shape cellular function. While many studies have investigated either environmental or genetic contributions to DNAm, few have assessed their integrated effects. Here we examine the relative contributions of prenatal environmental factors and genotype on DNA methylation in neonatal blood at variably methylated regions (VMRs) in 4 independent cohorts (overall n = 2365). We use Akaikeâs information criterion to test which factors best explain variability of methylation in the cohort-specific VMRs: several prenatal environmental factors (E), genotypes in cis (G), or their additive (G + E) or interaction (GxE) effects. Genetic and environmental factors in combination best explain DNAm at the majority of VMRs. The CpGs best explained by either G, G + E or GxE are functionally distinct. The enrichment of genetic variants from GxE models in GWAS for complex disorders supports their importance for disease risk
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