49 research outputs found
Theory of single-photon transport in a single-mode waveguide coupled to a cavity containing a two-level atom
The single-photon transport in a single-mode waveguide, coupled to a cavity
embedded with a two-leval atom is analyzed. The single-photon transmission and
reflection amplitudes, as well as the cavity and the atom excitation
amplitudes, are solved exactly via a real-space approach. It is shown that the
dissipation of the cavity and of the atom respectively affects distinctively on
the transport properties of the photons, and on the relative phase between the
excitation amplitudes of the cavity mode and the atom.Comment: 28 pages, 6 figures. Accepted by Physical Review A (2009
Robust Landmark-based Stent Tracking in X-ray Fluoroscopy
In clinical procedures of angioplasty (i.e., open clogged coronary arteries),
devices such as balloons and stents need to be placed and expanded in arteries
under the guidance of X-ray fluoroscopy. Due to the limitation of X-ray dose,
the resulting images are often noisy. To check the correct placement of these
devices, typically multiple motion-compensated frames are averaged to enhance
the view. Therefore, device tracking is a necessary procedure for this purpose.
Even though angioplasty devices are designed to have radiopaque markers for the
ease of tracking, current methods struggle to deliver satisfactory results due
to the small marker size and complex scenes in angioplasty. In this paper, we
propose an end-to-end deep learning framework for single stent tracking, which
consists of three hierarchical modules: U-Net based landmark detection, ResNet
based stent proposal and feature extraction, and graph convolutional neural
network (GCN) based stent tracking that temporally aggregates both spatial
information and appearance features. The experiments show that our method
performs significantly better in detection compared with the state-of-the-art
point-based tracking models. In addition, its fast inference speed satisfies
clinical requirements.Comment: Accepted by ECCV 202
Complete all-optical silica fiber isolator via stimulated Brillouin scattering
Abstract-This study demonstrates the theoretical operation of an all-optical silica fiber isolator using stimulated Brillouin scattering. Two pump sources that copropagate through a double-mode fiber generate acoustic waves through electrostriction. These acoustic waves then induce unidirectional interband optical transitions between a separate pair of signal sources. With 1 W of total input pump power, complete optical isolation is achieved with a silica rod waveguide of radius 0.67 m over a length of approximately 12 m, with pumps operating at a wavelength of 1.55 m and signals at 1.50 m
Simplified HIV Testing and Treatment in China: Analysis of Mortality Rates Before and After a Structural Intervention.
BackgroundMultistage stepwise HIV testing and treatment initiation procedures can result in lost opportunities to provide timely antiretroviral therapy (ART). Incomplete patient engagement along the continuum of HIV care translates into high levels of preventable mortality. We aimed to evaluate the ability of a simplified test and treat structural intervention to reduce mortality.Methods and findingsIn the "pre-intervention 2010" (from January 2010 to December 2010) and "pre-intervention 2011" (from January 2011 to December 2011) phases, patients who screened HIV-positive at health care facilities in Zhongshan and Pubei counties in Guangxi, China, followed the standard-of-care process. In the "post-intervention 2012" (from July 2012 to June 2013) and "post-intervention 2013" (from July 2013 to June 2014) phases, patients who screened HIV-positive at the same facilities were offered a simplified test and treat intervention, i.e., concurrent HIV confirmatory and CD4 testing and immediate initiation of ART, irrespective of CD4 count. Participants were followed for 6-18 mo until the end of their study phase period. Mortality rates in the pre-intervention and post-intervention phases were compared for all HIV cases and for treatment-eligible HIV cases. A total of 1,034 HIV-positive participants (281 and 339 in the two pre-intervention phases respectively, and 215 and 199 in the two post-intervention phases respectively) were enrolled. Following the structural intervention, receipt of baseline CD4 testing within 30 d of HIV confirmation increased from 67%/61% (pre-intervention 2010/pre-intervention 2011) to 98%/97% (post-intervention 2012/post-intervention 2013) (all p < 0.001 [i.e., for all comparisons between a pre- and post-intervention phase]), and the time from HIV confirmation to ART initiation decreased from 53 d (interquartile range [IQR] 27-141)/43 d (IQR 15-113) to 5 d (IQR 2-12)/5 d (IQR 2-13) (all p < 0.001). Initiation of ART increased from 27%/49% to 91%/89% among all cases (all p < 0.001) and from 39%/62% to 94%/90% among individuals with CD4 count ≤ 350 cells/mm3 or AIDS (all p < 0.001). Mortality decreased from 27%/27% to 10%/10% for all cases (all p < 0.001) and from 40%/35% to 13%/13% for cases with CD4 count ≤ 350 cells/mm3 or AIDS (all p < 0.001). The simplified test and treat intervention was significantly associated with decreased mortality rates compared to pre-intervention 2011 (adjusted hazard ratio [aHR] 0.385 [95% CI 0.239-0.620] and 0.380 [95% CI 0.233-0.618] for the two post-intervention phases, respectively, for all newly diagnosed HIV cases [both p < 0.001], and aHR 0.369 [95% CI 0.226-0.603] and 0.361 [95% CI 0.221-0.590] for newly diagnosed treatment-eligible HIV cases [both p < 0.001]). The unit cost of an additional patient receiving ART attributable to the intervention was US234.52.ConclusionsOur results demonstrate that the simplified HIV test and treat intervention promoted successful engagement in care and was associated with a 62% reduction in mortality. Our findings support the implementation of integrated HIV testing and immediate access to ART irrespective of CD4 count, in order to optimize the impact of ART
Ripk3 signaling regulates HSCs during stress and represses radiation-induced leukemia in mice
Receptor-interacting protein kinase 3 (Ripk3) is one of the critical mediators of inflammatory cytokine-stimulated signaling. Here we show that Ripk3 signaling selectively regulates both the number and the function of hematopoietic stem cells (HSCs) during stress conditions. Ripk3 signaling is not required for normal homeostatic hematopoiesis. However, in response to serial transplantation, inactivation of Ripk3 signaling prevents stress-induced HSC exhaustion and functional HSC attenuation, while in response to fractionated low doses of ionizing radiation (IR), inactivation of Ripk3 signaling accelerates leukemia/lymphoma development. In both situations, Ripk3 signaling is primarily stimulated by tumor necrosis factor-α. Activated Ripk3 signaling promotes the elimination of HSCs during serial transplantation and pre-leukemia stem cells (pre-LSCs) during fractionated IR by inducing Mlkl-dependent necroptosis. Activated Ripk3 signaling also attenuates HSC functioning and represses a pre-LSC-to-LSC transformation by promoting Mlkl-independent senescence. Furthermore, we demonstrate that Ripk3 signaling induces senescence in HSCs and pre-LSCs by attenuating ISR-mediated mitochondrial quality control
Roadmap on spatiotemporal light fields
Spatiotemporal sculpturing of light pulse with ultimately sophisticated
structures represents the holy grail of the human everlasting pursue of
ultrafast information transmission and processing as well as ultra-intense
energy concentration and extraction. It also holds the key to unlock new
extraordinary fundamental physical effects. Traditionally, spatiotemporal light
pulses are always treated as spatiotemporally separable wave packet as solution
of the Maxwell's equations. In the past decade, however, more generalized forms
of spatiotemporally nonseparable solution started to emerge with growing
importance for their striking physical effects. This roadmap intends to
highlight the recent advances in the creation and control of increasingly
complex spatiotemporally sculptured pulses, from spatiotemporally separable to
complex nonseparable states, with diverse geometric and topological structures,
presenting a bird's eye viewpoint on the zoology of spatiotemporal light fields
and the outlook of future trends and open challenges.Comment: This is the version of the article before peer review or editing, as
submitted by an author to Journal of Optics. IOP Publishing Ltd is not
responsible for any errors or omissions in this version of the manuscript or
any version derived from i