We derive the Q2 dependence of the helicity amplitudes of the Roper resonance assuming that it is (1) a radially excited q 3 state, and (2) a q 3~ hybrid baryon. Our study shows that for a hybrid baryon assignment the magnitude of the transverse helicity amplitude decreases rapidly as Q 2 increases, and the longitudinal helicity amplitude vanishes. This behavior is quite different from the predictions of the q 3 quark potential model, which assumes a radially excited q 3 assignment. Comparison with data shows that the hybrid interpretation of the Roper resonance is favored. Future experiments at the Continuous Electron Beam Accelerator Facility should be able to clearly distinguish between these two possible assignments.PACS number(s1: 13.60. Rj, 12.40.Aa, 14.20.Gk Hybrid baryons are states presumably dominated by the state of three quarks oscillating against explicitly excited glue field configurations. We denote these states by q3G. Within the framework of QCD, such configurations are expected to exist in nature. However, because QCD is not well understood in the nonperturbative regime, little is known about the masses of hybrid states, and mass estimates have to rely on the use of models. Estimates within the bag-model approach [I] showed that the gluonic excitation energy should be about 550-700 MeV. This suggests that the masses of the lightest hybrid baryons could be as low as < 1500 MeV. Therefore, it is possible that some of the experimentally observed baryons are hybrid states rather than ordinary q 3 states. Recently, it has been suggested [2] that there should be a gluonic partner of the nucleon whose ratio of "proton" and "neutron" magnetic moments and photoproduction helicity amplitudes is -$. It is possible that the Roper resonance P I , ( 1440) and P33( 16001, which, in the quark model, are assigned to radial excitations of the nucleon and P j 3 ( 1232), respectively, are such hybrid states. The low mass of the Roper resonance as well as of the P33( 1600) are difficult to explain within the framework of the quark potential model [3]. Moreover, there are indications of the existence of P3,(1550) and P,,(1540) states, which are expected to exist as hybrid states. but have no place in the quark potential model.Three quark states and hybrid states may have the same quantum numbers; a study of the spectroscopic assignments will therefore not be sufficient to discriminate between the q and q 3~ states. However, because of their different internal structure (spatial wave function), as well as their different spin-flavor structure, studies of transition properties, especially of the photon transition amplitudes and the electromagnetic transition form factors, may prove very effective in distinguishing between these states. A hybrid state is excited in the spin-flavor space, and has an SU(6) spin-flavor wave function orthogonal to that of the nucleon, whereas the spin-flavor wave function of a radially excited state is identical to that of the nucleon. The difference between the spin-flavor excitation a...

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CRISPR-Cas9 is a powerful new tool for genome editing, but this technique creates mosaic mutations that affect the efficiency and precision of its ability to edit the genome. Reducing mosaic mutations is particularly important for gene therapy and precision genome editing. Although the mechanisms underlying the CRSIPR/Cas9-mediated mosaic mutations remain elusive, the prolonged expression and activity of Cas9 in embryos could contribute to mosaicism in DNA mutations. Here we report that tagging Cas9 with ubiquitin-proteasomal degradation signals can facilitate the degradation of Cas9 in non-human primate embryos. Using embryo-splitting approach, we found that shortening the half-life of Cas9 in fertilized zygotes reduces mosaic mutations and increases its ability to modify genomes in non-human primate embryos. Also, injection of modified Cas9 in one-cell embryos leads to live monkeys with the targeted gene modifications. Our findings suggest that modifying Cas9 activity can be an effective strategy to enhance precision genome editing.CRISPR-Cas9 combines the type II bacterial clustered, regularly interspaced, palindromic repeats (CRISPR)-associated (Cas) system and a single guide RNA (gRNA), which targets Cas9 to genomic regions complementary to the gRNA 1 . Double-stranded DNA breaks at the targeted locus are generated by Cas9 digestion and repaired by non-homologous end-joining (NHEJ) or homology-directed repair (HDR), resulting in indel mutations [2][3]

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Observations of precipitating trade wind cumuli show convective invigoration on the downwind side of their cold pools. The authors study convection and cold pools using a nested-Weather Research and Forecasting Model simulation of 19 January 2005-a day from the Rain in Cumulus over the Ocean experiment. The temperature and water vapor mixing ratio drops in simulated cold pools fall within the envelope of observed cases, and the wind enhancement matches observations more closely. Subcloud updrafts downwind and near the cold pool boundary are statistically compared to updrafts further from cold pools. Updrafts near cold pool outflows are moister than the other updrafts and are more likely to originate from overall moister regions. Cold pool-influenced updrafts tend to exceed the other updrafts in vertical velocity and are associated with more cloud liquid water. The strength of circulation within the cold pool boundary is unable to match that because of the low-level environmental wind shear, and the lifted updrafts advect faster than the environmental wind, thereby accessing the ambient environmental moisture converged by cold pool expansion. Cases with higher rain rates correspond to larger cloud cover through the shearing off of the upperlevel cloud, consistent with observations. This study suggests that it is the ability of cold pools to lift thermodynamically favorable air that is critical for secondary convection of trade wind cumuli.

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