Age is a significant biomarker for the selection of neoadjuvant chemotherapy plus radiotherapy versus concurrent chemoradiotherapy in patients with advanced nasopharyngeal carcinoma.

BACKGROUND: The optimal timing of combined chemotherapy with radiotherapy for locally advanced nasopharyngeal carcinoma (LA-NPC) is undetermined. OBJECTIVE: This study aimed to compare the therapeutic efficacy of neoadjuvant chemotherapy (NACT) followed by radiotherapy (RT) and concurrent chemoradiotherapy (CCRT). METHODS: Five hundred and thirty-eight patients diagnosed with LA-NPC and treated with NACT + RT or CCRT alone were enrolled in the study. Restricted cubic spline regression (RCS) was used to determine the relationship between age and the hazard Ratio of death. A Kaplan-Meier analysis was performed to evaluate overall survival (OS) related to NACT + RT or CCRT alone. Cox proportional hazards models were used to adjust for potential confounding factors. RESULTS: Compared with the CCRT alone regimen, the NACT + RT regimen showed a significantly better OS rate with a 62% decreased risk of death in a subgroup of patients aged ⩾ 45 years (hazard ratio, HR: 0.38; 95% confidence interval, CI: 0.24-0.61). In patients aged < 45 years, the risk of death was significantly increased when NACT + RT was chosen compared with CCRT (HR: 4.10; 95% CI: 2.09-8.07). CONCLUSIONS: Age is a significant biomarker when selecting NACT + RT or CCRT alone in patients with locally advanced NPC.

Hybrid fiber-THz fronthaul supporting up to 16384-QAM-OFDM with the delta-sigma modulation.

With the progress of high-capacity radio access networks, ultra-dense small cells are rapidly being deployed in urban areas. As a result, the deployment of a large number of optical fibers in urban areas becomes a severe issue. In this Letter, we propose a hybrid fiber-terahertz (THz) mobile fronthaul system supporting flexible and high-order wireless signal transmission with the delta-sigma modulation. The photonic THz transmission is used as the seamless extension of fiber-based fronthaul in small cells. A 20-Gbit/s digital fiber-THz fronthaul system is experimentally demonstrated to validate the proposed scheme, with 10-km optical fiber transmission and 300-GHz wireless relay. Carrier aggregation of up to 10 40-MHz and 60-MHz 5G-new radio (5G-NR) channels at the radio carrier frequency of 3.9 GHz is reported. The design of quantization noise suppressed delta-sigma modulation enables the system to transmit orthogonal frequency division multiplexing (OFDM) modulation up to  16384 order quadrate amplitude modulation (QAM) mapping with the error vector magnitude (EVM) below 0.5%.

Effective-medium-cladded dielectric waveguides for terahertz waves.

Terahertz integrated platforms with high efficiency are crucial in a broad range of applications including terahertz communications, radar, imaging and sensing. One key enabling technology is wideband interconnection. This work proposes substrate-less all-dielectric waveguides defined by an effective medium with a subwavelength hole array. These self-supporting structures are built solely into a single silicon wafer to minimize significant absorption in metals and dielectrics at terahertz frequencies. In a stark contrast to photonic crystal waveguides, the guiding mechanism is not based on a photonic bandgap but total internal reflections The waveguides are discussed in the context of terahertz communications that imposes stringent demands on performance. Experimental results show that the realized waveguides can cover the entire 260-400 GHz with single dominant modes in both orthogonal polarizations and an average measured attenuation around 0.05 dB/cm. Limited by the measurement setup, the maximum error-free data rate up to 30 Gbit/s is experimentally achieved at 335 GHz on a 3-cm waveguide. We further demonstrate the transmission of uncompressed 4K-resolution video across this waveguide. This waveguide platform promises integration of diverse active and passive components. Thus, we can foresee it as a potential candidate for the future terahertz integrated circuits, in analogy to photonic integrated circuits at optical frequencies. The proposed concept can potentially benefit integrated optics at large.

Efficient mode converter to deep-subwavelength region with photonic-crystal waveguide platform for terahertz applications.

Metallic deep-subwavelength features can aid in integration of microscopic components or strong light-matter interaction with a low-loss dielectric waveguide platform. A mode converter or coupler is required to integrate the devices. However, there is a vast difference in the physical scale and modal distribution between the deep-subwavelength structures and the dielectric waveguide platform. Here, we employ a tapered-slot mode converter to facilitate the electromagnetic wave transition from a gap width smaller than 1/100 of a wavelength (λ) to a larger-scale mode that is amenable to a terahertz (THz) silicon photonic-crystal waveguide. The mode converter is metallic, and fabricated on top of indium phosphide substrate, leading to incongruity with the modal field distribution of the silicon photonic-crystal waveguide. To mitigate this, a sandwiched structure is developed to match the symmetry of the mode of photonic-crystal waveguide, thereby facilitating efficient transfer of energy. For a proof of concept, we integrate a resonant tunneling diode (< 2 µm) as a THz detector in a photonic-crystal waveguide platform in the 0.3-THz band (λ ∼ 1 mm). The coupling efficiency is close to unity (∼90%) with broadband operation (∼50 GHz) in experiments. Thereafter, we employ the developed integrated device as a receiver in a THz communication experiment. In this manner, we successfully achieve real-time error-free data transmission at 32 Gbit/s, and demonstrate wireless transmission of uncompressed 4K high-definition video.