5,361 research outputs found
Could a light Higgs boson illuminate the dark sector?
The impact a new neutral light particle of spin 0, 1/2, 1, or 3/2 could have
on the tiny width of a light Higgs boson is systematically analyzed. To this
end, we include all the relevant effective interactions, whether renormalizable
or not, and review the possible signatures in the Higgs decay modes with
missing energy. This includes the fully invisible Higgs boson decay, as well as
modes with SM gauge boson or fermions in the final state. In many cases, simply
preventing these modes from being dominant suffices to set tight
model-independent constraints on the masses and couplings of the new light
states.Comment: 21 pages, 7 figures. Minor changes; to appear in Phys. Rev.
Formation of Globular Cluster Candidates in Merging Proto-galaxies at High Redshift: A View from the FIRE Cosmological Simulations
Using a state-of-the-art cosmological simulation of merging proto-galaxies at
high redshift from the FIRE project, with explicit treatments of star formation
and stellar feedback in the interstellar medium, we investigate the formation
of star clusters and examine one of the formation hypothesis of present-day
metal-poor globular clusters. We find that frequent mergers in high-redshift
proto-galaxies could provide a fertile environment to produce long-lasting
bound star clusters. The violent merger event disturbs the gravitational
potential and pushes a large gas mass of ~> 1e5-6 Msun collectively to high
density, at which point it rapidly turns into stars before stellar feedback can
stop star formation. The high dynamic range of the reported simulation is
critical in realizing such dense star-forming clouds with a small dynamical
timescale, t_ff <~ 3 Myr, shorter than most stellar feedback timescales. Our
simulation then allows us to trace how clusters could become virialized and
tightly-bound to survive for up to ~420 Myr till the end of the simulation.
Because the cluster's tightly-bound core was formed in one short burst, and the
nearby older stars originally grouped with the cluster tend to be
preferentially removed, at the end of the simulation the cluster has a small
age spread.Comment: 14 pages, 14 figures, Accepted for publication in the Monthly Notices
of the Royal Astronomical Society, High-resolution version of this article
also available at http://www.jihoonkim.org/index/research.html#g
How to Get the Most from Microarray Data: Advice from Reverse Genomics
Whole-genome profiling of gene expression is a powerful tool for identifying cancer-associated genes. Genes differentially expressed between normal and tumorous tissues are usually considered to be cancer associated. We recently demonstrated that the analysis of interindividual variation in gene expression can be useful for identifying cancer associated genes. The goal of this study was to identify the best microarray data–derived predictor of known cancer associated genes. We found that the traditional approach of identifying cancer genes—identifying differentially expressed genes—is not very efficient. The analysis of interindividual variation of gene expression in tumor samples identifies cancer-associated genes more effectively. The results were consistent across 4 major types of cancer: breast, colorectal, lung, and prostate. We used recently reported cancer-associated genes (2011–2012) for validation and found that novel cancer-associated genes can be best identified by elevated variance of the gene expression in tumor samples
Refractory lympho-epithelial carcinoma of the nasopharynx: a case report illustrating a protracted clinical course
Nasopharyngeal carcinoma is an uncommon cancer in North America. Its clinical course is typified by locally advanced disease at diagnosis and has a high propensity for both regional and distant spread. It is, therefore, typically treated with a combination of radiation and chemotherapy. This report describes our 10-year clinical and radiological findings in a 48-year-old Vietnamese male patient with locally-advanced T4N1M0 lympho-epithelial carcinoma of the nasopharynx. Despite a long remission period after his initial course of aggressive chemoradiation, his tumor recurred locally after 4 years. Thereafter, throughout a period of over 10 years, he has been treated with multiple courses of re-irradiation and three different trials of chemotherapy. He was ultimately provided with over 30 months of progression-free tumor control with the epidermal growth factor receptor (EGFR)-inhibitor cetuximab. This case illustrates the commonly protracted course of this disease and its responsiveness to multiple treatment modalities
Path-integral analysis of fluctuation theorems for general Langevin processes
We examine classical, transient fluctuation theorems within the unifying
framework of Langevin dynamics. We explicitly distinguish between the effects
of non-conservative forces that violate detailed balance, and non-autonomous
dynamics arising from the variation of an external parameter. When both these
sources of nonequilibrium behavior are present, there naturally arise two
distinct fluctuation theorems.Comment: 24 pages, one figur
Vacuum ultraviolet photoabsorption spectra of nitrile ices for their identification on Pluto
Icy bodies, such as Pluto, are known to harbor simple and complex molecules. The recent New Horizons flyby of Pluto has revealed a complex surface composed of bright and dark ice surfaces, indicating a rich chemistry based on nitrogen (N2), methane (CH4), and carbon monoxide (CO). Nitrile (CN) containing molecules such as acetonitrile (CH3CN), propionitrile (CH3CH2CN), butyronitrile (CH3CH2CH2CN), and isobutyronitrile ((CH3)2CHCN) are some of the nitrile molecules that are known to be synthesized by radiative processing of such simple ices. Through the provision of a spectral atlas for such compounds we propose that such nitriles may be identified from the ALICE payload on board New Horizons</i
Rapid Screening of Calcium Carbonate Precipitation in the Presence of Amino Acids: Kinetics, Structure, and Composition
Soluble additives are widely used to control crystallization, leading to a definition of properties including size, morphology, polymorph, and composition. However, because of the number of potential variables in these experiments, it is typically extremely difficult to identify reaction conditions—as defined by solution compositions, temperatures, and combinations of additives—that give the desired product. This article introduces a high-throughput methodology which addresses this challenge and enables the streamlined preparation and characterization of crystalline materials. Using calcium carbonate precipitated in the presence of selected amino acids as a model system, we use well plates as microvolume crystallizers, and an accurate liquid-handling pipetting workstation for sample preparation. Following changes in the solution turbidity using a plate reader delivers information about the reaction kinetics, while semiautomated scanning electron microscopy, powder X-ray diffraction, and Raman microscopy provide structural information about the library of crystalline products. Of particular interest for the CaCO3 system is the development of fluorescence-based protocols which rapidly evaluate the amounts of the additives occluded within the crystals. Together, these methods provide a strategy for efficiently screening a broad reaction space, where this can both accelerate the ability to generate crystalline materials with target properties and develop our understanding of additive-directed crystallization
Yttrium-90 microsphere induced gastrointestinal tract ulceration
© 2008 South et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
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