3,383 research outputs found
Exploration of the postponing mechanism that delays carcinoma onset
The average age at onset of malignancies arising from epithelial tissues is between 40 and 70 years old even in familial cancers. Although it is believed that the accumulation of multiple genetic alterations is needed for cancer onset, we hypothesize--based on the diversity of ages at onset for most types of epithelial cancer--that there is a postponing mechanism inside the human body that significantly delays the process of carcinogenesis. The key molecules controlling the cancer onset, here called "postponers", are hypothesized to be functioning in the individuals carrying susceptibility genes. As a consequence, cancers occur in middle age or even old age, with several decades of cancer-free lifetime for the patient. Genome-wide association studies and genomic expression profiling are suggested to identify candidate postponers. Hypothetic gene expression patterns for identifying candidate postponers are illustrated. Animal models will be helpful to test whether the absence or presence of the postponer molecules can alter the onset age of spontaneous tumors. If this hypothesis is true, by amplification of the postponing mechanism we might be able to significantly delay the onset of tumors, so that individuals carrying cancer susceptibility traits could gain an additional significant period of cancer-free life. Moreover, destructive prophylactic surgeries, e.g., for women who have BRCA1/2 gene mutations, might be avoided
Exothermic isospin-violating dark matter after SuperCDMS and CDEX
We show that exothermic isospin-violating dark matter (IVDM) can make the
results of the latest CDMS-Si experiment consistent with recent null
experiments, such as XENON10, XENON100, LUX, CDEX, and SuperCDMS, whereas for
the CoGeNT experiment, a strong tension still persists. For CDMS-Si, separate
exothermic dark matter or isospin-violating dark matter cannot fully ameliorate
the tensions among these experiments; the tension disappears only if exothermic
scattering is combined with an isospin-violating effect of f_n/f_p=-0.7. For
such exothermic IVDM to exist, at least a new vector gauge boson (dark photon
or dark Z') that connects SM quarks to Majorana-type DM particles is required.Comment: 12 pages, 6 figure
Interacting heavy fermions in a disordered optical lattice
We have theoretically studied the effect of disorder on ultracold
alkaline-earth atoms governed by the Kondo lattice model in an optical lattice
via simplified double-well model and hybridization mean-field theory.
Disorder-induced narrowing and even complete closure of hybridization gap have
been predicted and the compressibility of the system has also been investigated
for metallic and Kondo insulator phases in the presence of the disordered
potential. To make connection to the experimental situation, we have
numerically solved the disordered Kondo lattice model with an external harmonic
trap and shown both the melting of Kondo insulator plateau and an
compressibility anomaly at low-density
Cyclotron Dynamics of a Kondo Singlet in a Spin-Orbit-Coupled Alkaline-Earth Atomic Gas
We propose a scheme to investigate the interplay between Kondo-exchange
interaction and quantum spin Hall effect with ultracold fermionic
alkaline-earth atoms trapped in two-dimensional optical lattices using
ultracold collision and laser-assisted tunneling. In the strong Kondo-coupling
regime, though the loop trajectory of the mobile atom disappears, collective
dynamics of an atom pair in two clock states can exhibit an unexpected
spin-dependent cyclotron orbit in a plaquette, realizing the quantum spin Hall
effect of the Kondo singlet. We demonstrate that the collective cyclotron
dynamics of the spin-zero Kondo singlet is governed by an effective
Harper-Hofstadter model in addition to second-order diagonal tunneling
Energy Efficiency Comparison of Hybrid Powertrain Systems for Fuel-Cell-Based Electric Vehicles
Fuel cell electric vehicles have great superiorities in endurance mileage, charging speed and climate tolerance compared to battery electric vehicles. However, a supercapacitor or battery bank is required to maintain a fast-dynamic response, which leads to several hybridization structures for fuel-cell-based electric vehicles due to the unique characteristics of each device, and their performances are also differing. The purpose of this paper is to provide a comprehensive comparison of hybrid powertrain systems for three types of powertrains: fuel cell/supercapacitor passive hybrid, fuel cell/supercapacitor semi-active hybrid, and fuel cell/battery semi-active hybrid. Each powertrain component model is developed from the real components wherever possible, and Honda FCX Clarity fuel cell vehicle is studied as the benchmark. The powertrain energy efficiency under Worldwide harmonized Light vehicles Test Cycle (WLTC) is analyzed and evaluated. The simulation results show that three powertrains have the same energy consumption, and fuel cell/supercapacitor passive hybrid powertrain increases the system efficiency by 2% and 4% in propulsion and regenerative braking, respectively. By contrast, the other two powertrain topologies have similar performance in terms of energy efficiency
Lifshitz Scaling Effects on Holographic Superconductors
Via numerical and analytical methods, the effects of the Lifshitz dynamical
exponent on holographic superconductors are studied in some detail,
including wave and wave models. Working in the probe limit, we find
that the behaviors of holographic models indeed depend on concrete value of
. We obtain the condensation and conductivity in both Lifshitz black hole
and soliton backgrounds with general . For both wave and wave models
in the black hole backgrounds, as increases, the phase transition becomes
more difficult and the growth of conductivity is suppressed. For the Lifshitz
soliton backgrounds, when increases (), the critical chemical
potential decreases in the wave cases but increases in the wave cases.
For wave models in both Lifshitz black hole and soliton backgrounds, the
anisotropy between the AC conductivity in different spatial directions is
suppressed when increases. The analytical results uphold the numerical
results.Comment: Typos corrected; Footnote added; References added; To be published in
Nuclear Physics
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