2,710 research outputs found
Single Transverse Spin Asymmetries at Parton Level
Two factorization approaches have been proposed for single transverse spin
asymmetries. One is the collinear factorization, another is the
transverse-momentum-dependent factorization. They have been previously derived
in a formal way by using diagram expansion at hadron level. If the two
factorizations hold or can be proven, they should also hold when we replace
hadrons with parton states. We examine these two factorizations at parton level
with massless partons. It is nontrivial to generate these asymmetries at parton
level with massless partons because the asymmetries require helicity-flip and
nonzero absorptive parts in scattering amplitudes. By constructing suitable
parton states with massless partons we derive the two factorizations for the
asymmetry in Drell-Yan processes. It is found from our results that the
collinear factorization derived at parton level is not the same as that derived
at hadron level. Our results with massless partons confirm those derived with
single massive parton state in our previous works.Comment: shortened version to match published versio
Electronic properties of a quantum wire with arbitrary bending angle
The electron transmission and bound state properties of a quantum wire with a sharp bend at arbitrary angle are studied, extending results on the right angle sharp bend (the L¿shaped wire). These new results are compared to those of a similar structure, the circular bend wire. The possibility of using a bent wire to perform transistor action is also discussed
Revision of the Late Jurassic teleosaurid genus Machimosaurus (Crocodylomorpha, Thalattosuchia)
© 2014 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. The attached file is the published version of the article
Two-Copy Wavelength Conversion of an 80 Gbit/s Serial Data Signal Using Cross-Phase Modulation in a Silicon Nanowire and Detailed Pump-Probe Characterisation
Fully gapped topological surface states in BiSe films induced by a d-wave high-temperature superconductor
Topological insulators are a new class of materials, that exhibit robust
gapless surface states protected by time-reversal symmetry. The interplay
between such symmetry-protected topological surface states and symmetry-broken
states (e.g. superconductivity) provides a platform for exploring novel quantum
phenomena and new functionalities, such as 1D chiral or helical gapless
Majorana fermions, and Majorana zero modes which may find application in
fault-tolerant quantum computation. Inducing superconductivity on topological
surface states is a prerequisite for their experimental realization. Here by
growing high quality topological insulator BiSe films on a d-wave
superconductor BiSrCaCuO using molecular beam epitaxy,
we are able to induce high temperature superconductivity on the surface states
of BiSe films with a large pairing gap up to 15 meV. Interestingly,
distinct from the d-wave pairing of BiSrCaCuO, the
proximity-induced gap on the surface states is nearly isotropic and consistent
with predominant s-wave pairing as revealed by angle-resolved photoemission
spectroscopy. Our work could provide a critical step toward the realization of
the long sought-after Majorana zero modes.Comment: Nature Physics, DOI:10.1038/nphys274
Non-Equilibrium Field Dynamics of an Honest Holographic Superconductor
Most holographic models of superconducting systems neglect the effects of
dynamical boundary gauge fields during the process of spontaneous
symmetry-breaking. Usually a global symmetry gets broken. This yields a
superfluid, which then is gauged "weakly" afterwards. In this work we build
(and probe the dynamics of) a holographic model in which a local boundary
symmetry is spontaneously broken instead. We compute two-point functions of
dynamical non-Abelian gauge fields in the normal and in the broken phase, and
find non-trivial gapless modes. Our AdS3 gravity dual realizes a p-wave
superconductor in (1+1) dimensions. The ground state of this model also breaks
(1+1)-dimensional parity spontaneously, while the Hamiltonian is
parity-invariant. We discuss possible implications of our results for a wider
class of holographic liquids.Comment: 32 pages, 12 figures; v3: string theory derivation of setup added
(section 3.1), improved presentation, version accepted by JHEP; v2: paragraph
added to discussion, figure added, references added, typos correcte
Nanocavity-mediated Purcell enhancement of Er in TiO thin films grown via atomic layer deposition
The use of trivalent erbium (Er), typically embedded as an atomic
defect in the solid-state, has widespread adoption as a dopant in
telecommunications devices and shows promise as a spin-based quantum memory for
quantum communication. In particular, its natural telecom C-band optical
transition and spin-photon interface makes it an ideal candidate for
integration into existing optical fiber networks without the need for quantum
frequency conversion. However, successful scaling requires a host material with
few intrinsic nuclear spins, compatibility with semiconductor foundry
processes, and straightforward integration with silicon photonics. Here, we
present Er-doped titanium dioxide (TiO) thin film growth on silicon
substrates using a foundry-scalable atomic layer deposition process with a wide
range of doping control over the Er concentration. Even though the as-grown
films are amorphous, after oxygen annealing they exhibit relatively large
crystalline grains, and the embedded Er ions exhibit the characteristic optical
emission spectrum from anatase TiO. Critically, this growth and annealing
process maintains the low surface roughness required for nanophotonic
integration. Finally, we interface Er ensembles with high quality factor Si
nanophotonic cavities via evanescent coupling and demonstrate a large Purcell
enhancement (300) of their optical lifetime. Our findings demonstrate a
low-temperature, non-destructive, and substrate-independent process for
integrating Er-doped materials with silicon photonics. At high doping densities
this platform can enable integrated photonic components such as on-chip
amplifiers and lasers, while dilute concentrations can realize single ion
quantum memories.Comment: 5 figure
Winter hardiness of \u3ci\u3eMiscanthus\u3c/i\u3e (III): Genome‐wide association and genomic prediction for overwintering ability in \u3ci\u3eMiscanthus sinensis\u3c/i\u3e
Overwintering ability is an important selection criterion for Miscanthus breeding in temperate regions. Insufficient overwintering ability of the currently leading Miscanthus biomass cultivar, M. ×giganteus (M×g) ‘1993–1780’, in regions where average annual minimum temperatures are −26.1°C (USDA hardiness zone 5) or lower poses a pressing need to develop new cultivars with superior cold tolerance. To facilitate breeding of Miscanthus, this study characterized phenotypic and genetic variation of overwintering ability in an M. sinensis germplasm panel consisting of 564 accessions, evaluated in field trials at three locations in North America and two in Asia. Genome‐wide association (GWA) and genomic prediction analyses were performed. The Korea/N China M. sinensis genetic group is a valuable gene pool for cold tolerance. The Yangtze‐Qinling, Southern Japan, and Northern Japan genetic groups were also potential sources of cold tolerance. A total of 73 marker–trait associations were detected for overwintering ability. Estimated breeding value for overwintering ability based on these 73 markers could explain 55% of the variation for first winter overwintering ability among M. sinensis. Average genomic prediction ability for overwintering ability across 50 fivefold cross‐validations was high (~0.73) after accounting for population structure. Common genomic regions for overwintering ability were detected by GWA analyses and a previous parallel QTL mapping study using three interconnected biparental F1 populations. One QTL on Miscanthus LG 8 encompassed five GWA hits and a known cold‐responsive gene, COR47. The other overwintering ability QTL on Miscanthus LG 11 contained two GWA hits and three known cold stress‐related genes, carboxylesterase 13 (CEX13), WRKY2 transcription factor, and cold shock domain (CSDP1). Miscanthus accessions collected from high latitude locations with cold winters had higher rates of overwintering, and more alleles for overwintering, than accessions collected from southern locations with mild winters
Metastatic Tumor Evolution and Organoid Modeling Implicate TGFBR2 as a Cancer Driver in Diffuse Gastric Cancer
Background: Gastric cancer is the second-leading cause of global cancer deaths, with metastatic disease representing the primary cause of mortality. To identify candidate drivers involved in oncogenesis and tumor evolution, we conduct an extensive genome sequencing analysis of metastatic progression in a diffuse gastric cancer. This involves a comparison between a primary tumor from a hereditary diffuse gastric cancer syndrome proband and its recurrence as an ovarian metastasis.
Results: Both the primary tumor and ovarian metastasis have common biallelic loss-of-function of both the CDH1 and TP53 tumor suppressors, indicating a common genetic origin. While the primary tumor exhibits amplification of the Fibroblast growth factor receptor 2 (FGFR2) gene, the metastasis notably lacks FGFR2 amplification but rather possesses unique biallelic alterations of Transforming growth factor-beta receptor 2 (TGFBR2), indicating the divergent in vivo evolution of a TGFBR2-mutant metastatic clonal population in this patient. As TGFBR2 mutations have not previously been functionally validated in gastric cancer, we modeled the metastatic potential of TGFBR2 loss in a murine three-dimensional primary gastric organoid culture. The Tgfbr2 shRNA knockdown within Cdh1-/-; Tp53-/- organoids generates invasion in vitro and robust metastatic tumorigenicity in vivo, confirming Tgfbr2 metastasis suppressor activity.
Conclusions: We document the metastatic differentiation and genetic heterogeneity of diffuse gastric cancer and reveal the potential metastatic role of TGFBR2 loss-of-function. In support of this study, we apply a murine primary organoid culture method capable of recapitulating in vivo metastatic gastric cancer. Overall, we describe an integrated approach to identify and functionally validate putative cancer drivers involved in metastasi
Complex in vitro 3D models of digestive system tumors to advance precision medicine and drug testing: Progress, challenges, and trends
Digestive system cancers account for nearly half of all cancers around the world and have a high mortality rate. Cell culture and animal models represent cornerstones of digestive cancer research. However, their ability to en- able cancer precision medicine is limited. Cell culture models cannot retain the genetic and phenotypic heteroge- neity of tumors and lack tumor microenvironment (TME). Patient-derived xenograft mouse models are not suitable for immune-oncology research. While humanized mouse models are time- and cost-consuming. Suitable preclinical models, which can facilitate the understanding of mechanisms of tumor progression and develop new therapeutic strategies, are in high demand. This review article summarizes the recent progress on the establish- ment of TME by using tumor organoid models and microfluidic systems. The main challenges regarding the translation of organoid models from bench to bedside are discussed. The integration of organoids and a microflu- idic platform is the emerging trend in drug screening and precision medicine. A future prospective on this field is also provided.This study was supported by the National Natural Science Foundation of China (Grant No.82073148), the Guangdong Provincial Key Laboratory of Digestive Cancer Research (No. 2021B1212040006), the Sanming Project of Medicine in Shenzhen (SZSM201911010), the Shenzhen Key Medical Discipline Construction Fund (SZXK016), the Shenzhen Sustainable Project (KCXFZ202002011010593), and the Shenzhen-Hong Kong-Macau Technology Research Programme (Type C) (Grant No. SGDX2020110309260100)
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