Traumatic brain injury in elderly population: A global systematic review and meta-analysis of in-hospital mortality and risk factors among 2.22 million individuals.

BACKGROUND: Traumatic brain injury (TBI) among elderly individuals poses a significant global health concern due to the increasing ageing population. METHODS: We searched PubMed, Cochrane Library, and Embase from database inception to Feb 1, 2024. Studies performed in inpatient settings reporting in-hospital mortality of elderly people (≥60 years) with TBI and/or identifying risk factors predictive of such outcomes, were included. Data were extracted from published reports, in-hospital mortality as our main outcome was synthesized in the form of rates, and risk factors predicting in-hospital mortality was synthesized in the form of odds ratios. Subgroup analyses, meta-regression and dose-response meta-analysis were used in our analyses. FINDINGS: We included 105 studies covering 2217,964 patients from 30 countries/regions. The overall in-hospital mortality of elderly patients with TBI was 16 % (95 % CI 15 %-17 %) from 70 studies. In-hospital mortality was 5 % (95 % CI, 3 %-7 %), 18 % (95 % CI, 12 %-24 %), 65 % (95 % CI, 59 %-70 %) for mild, moderate and severe subgroups from 10, 7, and 23 studies, respectively. A decrease in in-hospital mortality over years was observed in overall (1981-2022) and in severe (1986-2022) elderly patients with TBI. Older age 1.69 (95 % CI, 1.58-1.82, P < 0.001), male gender 1.34 (95 % CI, 1.25-1.42, P < 0.001), clinical conditions including traffic-related cause of injury 1.22 (95 % CI, 1.02-1.45, P = 0.029), GCS moderate (GCS 9-12 compared to GCS 13-15) 4.33 (95 % CI, 3.13-5.99, P < 0.001), GCS severe (GCS 3-8 compared to GCS 13-15) 23.09 (95 % CI, 13.80-38.63, P < 0.001), abnormal pupillary light reflex 3.22 (95 % CI, 2.09-4.96, P < 0.001), hypotension after injury 2.88 (95 % CI, 1.06-7.81, P = 0.038), polytrauma 2.31 (95 % CI, 2.03-2.62, P < 0.001), surgical intervention 2.21 (95 % CI, 1.22-4.01, P = 0.009), pre-injury health conditions including pre-injury comorbidity 1.52 (95 % CI, 1.24-1.86, P = 0.0020), and pre-injury anti-thrombotic therapy 1.51 (95 % CI, 1.23-1.84, P < 0.001) were related to higher in-hospital mortality in elderly patients with TBI. Subgroup analyses according to multiple types of anti-thrombotic drugs with at least two included studies showed that anticoagulant therapy 1.70 (95 % CI, 1.04-2.76, P = 0.032), Warfarin 2.26 (95 % CI, 2.05-2.51, P < 0.001), DOACs 1.99 (95 % CI, 1.43-2.76, P < 0.001) were related to elevated mortality. Dose-response meta-analysis of age found an odds ratio of 1.029 (95 % CI, 1.024-1.034, P < 0.001) for every 1-year increase in age on in-hospital mortality. CONCLUSIONS: In the field of elderly patients with TBI, the overall in-hospital mortality and its temporal-spatial feature, the subgroup in-hospital mortalities according to injury severity, and dose-response meta-analysis of age were firstly comprehensively summarized. Substantial key risk factors, including the ones previously not elucidated, were identified. Our study is thus of help in underlining the importance of treating elderly TBI, providing useful information for healthcare providers, and initiating future management guidelines. This work underscores the necessity of integrating elderly TBI treatment and management into broader health strategies to address the challenges posed by the aging global population. REVIEW REGISTRATION: PROSPERO CRD42022323231.

Adiabatic weak coherent MHz linewidth O-band single-photon carrier for low erroneous phase decoding.

For weak coherent single-photon secure data communication among short-reach metropolitan intra-/inter-city networks at the O-band (1250-1350 nm), the commercially available semiconductor laser sources are emerging but still suffering from high single-mode-fiber (SMF) loss, broad linewidth, and unstable wavelength. To overcome such disadvantages for enabling the efficient phase-coding link with sufficient secure key rate, a specifically designed adiabatic package with active temperature-/current-feedback control is proposed for the paired O-band MHz-linewidth master-to-slave injection-locked DFBLDs and a polarization-maintaining 1-bit-delay interferometer is stabilized with using a passively adiabatic cell to achieve accurate differential phase decoding. Even though, the phonon-induced phase fluctuation still occurs at rising and falling edges of the decoded long-pattern secure data bits delivered from the slave DFBLD, which is mainly attributed to the intra-cavity heating under excessive free-carrier generation via the master DFBLD injection. To stabilize the differential-phase-shift (DPS) keying protocol, the phase-code distortion caused by over-injection-induced Auger heating is effectively suppressed by reducing the overly biased injection with precise master-injection-level control. The rising-/falling-edge damping distortion of the phase-shift-encoded secure bit-stream envelope is suppressed by appropriately decreasing the DC bias current and adjusting the AC encoding amplitude of the master DFBLD. Such operation reduces the incorrect π phase shift in the injection-locked slave DFBLD biased at optimized below-threshold DC offset, thus allowing single-photon DPS-keying data transmission over 15-km SMF with slightly increasing the single-photon bit-error ratio from <3% (0-km) to 6.2% (15-km).

[Effects of orthodontic treatment combined with bone level implant in repairing dentition defect].

PURPOSE: To analyze the effect of orthodontic treatment combined with bone level implant in repairing dentition defect. METHODS: The data of 88 patients with single dental implant in mandibular posterior region who were treated for dentition defect from January 2020 to January 2022 were retrospectively analyzed, including 44 patients with bone level implant repair(control group) and 44 patients with orthodontic treatment combined bone level implant repair (experimental group). The success rate of implant implantation, periodontal health status, masticatory function, implant stability, postoperative complications and implant satisfaction were compared between the two groups. Statistical analysis was performed with SPSS 18.0 software package. RESULTS: There was no significant difference in the success rate of implant implantation at 3 months and 6 months between the two groups(P＞0.05). The success rate of implant implantation at 12 months in the experimental group was significantly higher than that in the control group (P＜0.05). The gingival sulci bleeding index (SBI) and probing depth (PD) of the experimental group were significantly lower than those of the control group at 12 months after implantation (P＜0.05), and there was no significant different in bone absorption between the two groups at 12 months after implantation(P＞0.05). The EMG activities of masseter muscle and temporal muscle in the two groups were significantly higher than those before treatment(P＜0.05), and those of masseter muscle and temporal muscle in the experimental group were significantly higher than those in the control group (P＜0.05). The implant stability coefficient values of 6 months and 12 months in 2 groups were significantly higher than those of 3 months (P＜0.05), the implant stability coefficient values of 12 months in 2 groups were significantly higher than those of 6 months and 12 months in 2 groups (P＜0.05), and the implant stability coefficient values of 6 months and 12 months in the experimental group were significantly higher than those in the control group(P＜0.05). There was no significant difference in the total complication rate between the two groups (P＞0.05). The implant satisfaction of the experimental group was significantly higher than that of the control group (P＜0.05). CONCLUSIONS: Orthodontic treatment combined with bone level implants can improve the success rate of implantation and masticatory efficiency, enhance the periodontal health of implants, and increase the patients' satisfaction with implants.

Advancing high-performance visible light communication with long-wavelength InGaN-based micro-LEDs.

This study showcases a method for achieving high-performance yellow and red micro-LEDs through precise control of indium content within quantum wells. By employing a hybrid quantum well structure with our six core technologies, we can accomplish outstanding external quantum efficiency (EQE) and robust stripe bandwidth. The resulting 30 µm × 8 micro-LED arrays exhibit maximum EQE values of 11.56% and 5.47% for yellow and red variants, respectively. Notably, the yellow micro-LED arrays achieve data rates exceeding 1 Gbit/s for non-return-to-zero on-off keying (NRZ-OOK) format and 1.5 Gbit/s for orthogonal frequency-division multiplexing (OFDM) format. These findings underscore the significant potential of long-wavelength InGaN-based micro-LEDs, positioning them as highly promising candidates for both full-color microdisplays and visible light communication applications.

Myosin Va-dependent Transport of NMDA Receptors in Hippocampal Neurons.

N-methyl-D-aspartate receptor (NMDAR) trafficking is a key process in the regulation of synaptic efficacy and brain function. However, the molecular mechanism underlying the surface transport of NMDARs is largely unknown. Here we identified myosin Va (MyoVa) as the specific motor protein that traffics NMDARs in hippocampal neurons. We found that MyoVa associates with NMDARs through its cargo binding domain. This association was increased during NMDAR surface transport. Knockdown of MyoVa suppressed NMDAR transport. We further demonstrated that Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates NMDAR transport through its direct interaction with MyoVa. Furthermore, MyoVa employed Rab11 family-interacting protein 3 (Rab11/FIP3) as the adaptor proteins to couple themselves with NMDARs during their transport. Accordingly, the knockdown of FIP3 impairs hippocampal memory. Together, we conclude that in hippocampal neurons, MyoVa conducts active transport of NMDARs in a CaMKII-dependent manner.

Synthesis of Nano-Structured Ge as Transmissive or Reflective Saturable Absorber for Mode-Locked Fiber Laser.

Amorphous-Ge (α-Ge) or free-standing nanoparticles (NPs) synthesized via hydrogen-free plasma-enhanced chemical vapor deposition (PECVD) were applied as transmissive or reflective saturable absorbers, respectively, for starting up passively mode-locked erbium-doped fiber lasers (EDFLs). Under a threshold pumping power of 41 mW for mode-locking the EDFL, the transmissive α-Ge film could serve as a saturable absorber with a modulation depth of 52-58%, self-starting EDFL pulsation with a pulsewidth of approximately 700 fs. Under a high power of 155 mW, the pulsewidth of the EDFL mode-locked by the 15 s-grown α-Ge was suppressed to 290 fs, with a corresponding spectral linewidth of 8.95 nm due to the soliton compression induced by intra-cavity self-phase modulation. The Ge-NP-on-Au (Ge-NP/Au) films could also serve as a reflective-type saturable absorber to passively mode-lock the EDFL with a broadened pulsewidth of 3.7-3.9 ps under a high-gain operation with 250 mW pumping power. The reflection-type Ge-NP/Au film was an imperfect mode-locker, owing to their strong surface-scattered deflection in the near-infrared wavelength region. From the abovementioned results, both ultra-thin α-Ge film and free-standing Ge NP exhibit potential as transmissive and reflective saturable absorbers, respectively, for ultrafast fiber lasers.

Effect of intracranial pressure on photoplethysmographic waveform in different cerebral perfusion territories: A computational study.

Background: Intracranial photoplethysmography (PPG) signals can be measured from extracranial sites using wearable sensors and may enable long-term non-invasive monitoring of intracranial pressure (ICP). However, it is still unknown if ICP changes can lead to waveform changes in intracranial PPG signals. Aim: To investigate the effect of ICP changes on the waveform of intracranial PPG signals of different cerebral perfusion territories. Methods: Based on lump-parameter Windkessel models, we developed a computational model consisting three interactive parts: cardiocerebral artery network, ICP model, and PPG model. We simulated ICP and PPG signals of three perfusion territories [anterior, middle, and posterior cerebral arteries (ACA, MCA, and PCA), all left side] in three ages (20, 40, and 60 years) and four intracranial capacitance conditions (normal, 20% decrease, 50% decrease, and 75% decrease). We calculated following PPG waveform features: maximum, minimum, mean, amplitude, min-to-max time, pulsatility index (PI), resistive index (RI), and max-to-mean ratio (MMR). Results: The simulated mean ICPs in normal condition were in the normal range (8.87-11.35 mm Hg), with larger PPG fluctuations in older subject and ACA/PCA territories. When intracranial capacitance decreased, the mean ICP increased above normal threshold (>20 mm Hg), with significant decreases in maximum, minimum, and mean; a minor decrease in amplitude; and no consistent change in min-to-max time, PI, RI, or MMR (maximal relative difference less than 2%) for PPG signals of all perfusion territories. There were significant effects of age and territory on all waveform features except age on mean. Conclusion: ICP values could significantly change the value-relevant (maximum, minimum, and amplitude) waveform features of PPG signals measured from different cerebral perfusion territories, with negligible effect on shape-relevant features (min-to-max time, PI, RI, and MMR). Age and measurement site could also significantly influence intracranial PPG waveform.

Effect of radiative and nonradiative energy transfer processes of light-emitting diodes combined with quantum dots for visible light communication.

Though light-emitting diodes (LEDs) combined with various color conversion techniques have been widely explored for VLC (visible light communication), E-O (electro-optical) frequency responses of devices with quantum dots (QDs) embedded within the nanoholes have rarely been addressed. Here we propose LEDs with embedded photonic crystal (PhC) nanohole patterns and green light QDs for studying small-signal E-O frequency bandwidths and large signal on-off keying E-O responses. We observe that the E-O modulation quality of PhC LEDs with QDs is better than a conventional LED with QDs when the overall blue mixed with green light output signal is considered. However, the optical response of only QD converted green light shows a contradictory result. The slower E-O conversion response is attributed to multi-path green light generation from both radiative and nonradiative energy transfer processes for QDs coated on the PhC LEDs.

Coupling angle tolerance of the 850-nm single-mode VCSEL output collimated by lensed OM4-MMF or GI-SMF for a NRZ-OOK link.

By collimating the single-mode (SM) vertical-cavity surface-emitting laser (VCSEL) at 850 nm with either the OM4 multi-mode fiber (OM4-MMF) or the graded-index single-mode fiber (GI-SMF) with lensed end-face, the directly encoded non-return-to-zero on-off keying (NRZ-OOK) data transmission performance is characterized when tilting the coupling angle with respect to the surface normal of the SM-VCSEL. In comparison with the lensed OM4-MMF and lensed SMF coupling, the lensed OM4-MMF collimator shows a large coupling angle tolerance with the coupling efficiency only degraded by 5% when enlarging the tilted angle from 0° to 10°. In contrast, the lensed GI-SMF collimator attenuates the coupled SM-VCSEL output by more than 50% when tilting the coupling angle up to 10°. For the lensed OM4-MMF coupling, the receivable NRZ-OOK data rate in BtB and after 100-m OM4-MMF cases can achieve 50 Gbit/s with its corresponding BER degraded from 6.5 × 10-10 to 8.8 × 10-10 when enlarging its tilting angle ranged from 0° to 10°. By changing the collimator to the lensed SMF, the decoded BER significantly degrades from 5.8 × 10-5 to 1.2 × 10-1 when coupling and transmitting the NRZ-OOK data at 50 Gbit/s. Owing to the low coupling efficiency via the lensed SMF collimator, the error-free NRZ-OOK data rate under the lensed SMF coupling somewhat decreases to 35 Gbit/s in the BtB link and to 32 Gbit/s after the 100-m GI-SMF link with allowable coupling angle tilted from 0° to 4°. This work confirms the applicability of the lensed MMF or SMF collimator for coupling the SM-VCSEL output with a relatively large tolerance on the tilting angle with respect to the surface normal of the SM-VCSEL.

Trafficking of NMDA receptors is essential for hippocampal synaptic plasticity and memory consolidation.

NMDA receptor (NMDAR) plays a vital role in brain development and normal physiological functions. Surface trafficking of NMDAR contributes to the modulation of synaptic functions and information processing. However, it remains unclear whether NMDAR trafficking is independent of long-term potentiation (LTP) and whether it regulates behavior. Here, we report that LTP of AMPAR and NMDAR can occur concurrently and that NMDAR trafficking can regulate AMPAR trafficking and AMPAR-mediated LTP. By contrast, AMPAR trafficking does not impact NMDAR-mediated LTP. Using SAP97-interfering peptide and SAP97 knockin (KI) rat, we show that the effect is mediated by GluN2A-subunit-containing NMDARs. At the behavior level, impaired NMDAR trafficking results in deficits in consolidation, but not acquisition, of fear memory. Collectively, our results suggest the essential role of NMDAR trafficking in LTP and memory consolidation.

Low-Temperature PECVD Growth of Germanium for Mode-Locking of Er-Doped Fiber Laser.

A low-temperature plasma-enhanced chemical vapor deposition grown germanium (Ge) thin-film is employed as a nonlinear saturable absorber (SA). This Ge SA can passively mode-lock the erbium-doped fiber laser (EDFL) for soliton generation at a central wavelength of 1600 nm. The lift-off and transfer of the Ge film synthesized upon the SiO2/Si substrate are performed by buffered oxide etching and direct imprinting. The Ge film with a thickness of 200 nm exhibits its Raman peak at 297 cm-1, which both the nanocrystalline and polycrystalline Ge phases contribute to. In addition, the Ge thin-film is somewhat oxidized but still provides two primary crystal phases at the (111) and (311) orientations with corresponding diffraction ring radii of 0.317 and 0.173 nm, respectively. The nanocrystalline structure at (111) orientation with a corresponding d-spacing of 0.319 nm is also observed. The linear and nonlinear transmittances of the Ge thin-film are measured to show its self-amplitude modulation coefficient of 0.016. This is better than nano-scale charcoal and carbon-black SA particles for initiating the mode-locking at the first stage. After the Ge-based saturable absorber into the L-band EDFL system without using any polarized components, the narrowest pulsewidth and broadest linewidth of the soliton pulse are determined as 654.4 fs and 4.2 nm, respectively, with a corresponding time-bandwidth product of 0.32 under high pumping conditions.

Low-Power Photodetectors Based on PVA-Modified Reduced Graphene Oxide Hybrid Solutions.

Photodetectors based on reduced graphene oxide (rGO) have attracted much attention owing to their simple and low-cost fabrication process. However, the aggregation and defects of rGO flakes still limit the performance of rGO photodetectors. Controlling the composition of rGO has become a vital factor for its prospective applications. For example, the interconnection between rGO and polymers for modified morphologies of rGO films leads to an enhanced performance of devices. In this work, a practical approach to engineer surface uniformity and enhance the performance of a photodetector by modifying the rGO film with hydrophilic polymers poly(vinyl alcohol) (PVA) is reported. Compared with the rGO photodetector, the on/off ratio for the PVA/rGO photodetector shows 3.5 times improvement, and the detectivity shows 53% enhancement even when the photodetector is operated at a low bias of 0.3 V. This study provides an effective route to realize PVA/rGO photodetectors with a low-power operation which shows promising opportunities for the future development of green systems.

Beyond GHz optical frequency up-converted modulation of LEDs with integrated acousto-optic transducer.

Traditional visible light communication (VLC) via light-emitting diodes (LEDs) employs the on-off keying (OOK) modulation scheme. Even though optical frequency modulation has many advantages, it is hardly used for LED VLC because a high carrier frequency cannot be applied to the LED cavity due to the resistance-capacitance limit. Here, by monolithically integrating an LED with an integrated digital transducer, we experimentally demonstrate the intermixing of gigahertz surface acoustic waves and electrical data signals in the LED cavity at room temperature. An optical transmitter was realized by in situ frequency up-conversion of the data signals from an LED, which has the advantages of improving transmission performance by up-shifting the data spectrum away from low-frequency noise. Our proposed integrated acousto-optic transducer opens a new developing scheme on the frequency up-mixed data encoding of an LED beyond its inherent modulation bandwidth for future VLC.

NMDAR-dependent somatic potentiation of synaptic inputs is correlated with ß amyloid-mediated neuronal hyperactivity.

BACKGROUND: ß Amyloid (Aß)-mediated neuronal hyperactivity, a key feature of the early stage of Alzheimer's disease (AD), is recently proposed to be initiated by the suppression of glutamate reuptake. Nevertheless, the underlying mechanism by which the impaired glutamate reuptake causes neuronal hyperactivity remains unclear. Chronic suppression of the glutamate reuptake causes accumulation of ambient glutamate that could diffuse from synaptic sites at the dendrites to the soma to elevate the tonic activation of somatic N-methyl-D-aspartate receptors (NMDARs). However, less attention has been paid to the potential role of tonic activity change in extrasynaptic glutamate receptors (GluRs) located at the neuronal soma on generation of neuronal hyperactivity. METHODS: Whole-cell patch-clamp recordings were performed on CA1 pyramidal neurons in acute hippocampal slices exposed to TFB-threo-ß-benzyloxyaspartic acid (TBOA) or human Aß1-42 peptide oligomer. A series of dendritic patch-clamp recordings were made at different distances from the soma to identify the location of the changes in synaptic inputs. Moreover, single-channel recording in the cell-attached mode was performed to investigate the activity changes of single NMDARs at the soma. RESULTS: Blocking glutamate uptake with either TBOA or the human Aß1-42 peptide oligomer elicited potentiation of synaptic inputs in CA1 hippocampal neurons. Strikingly, this potentiation  specifically occurred at the soma, depending on the activation of somatic GluN2B-containing NMDARs (GluN2B-NMDARs) and accompanied by a substantial and persistent increment in the open probability of somatic NMDARs. Blocking the activity of GluN2B-NMDARs at the soma completely reversed both the TBOA-induced or the Aß1-42-induced somatic potentiation and neuronal hyperactivity. CONCLUSIONS: The somatic potentiation of synaptic inputs may represent a novel amplification mechanism that elevates cell excitability and thus contributes to neuronal hyperactivity initiated by impaired glutamate reuptake in AD.

Higher order mode supercontinuum generation in tantalum pentoxide (Ta2O5) channel waveguide.

We fabricated tantalum pentoxide (Ta2O5) channel waveguides and used them to experimentally demonstrate higher-order mode supercontinuum (SC) generation. The Ta2O5 waveguide has a high nonlinear refractive index which was in an order magnitude of 10-14 cm2/W and was designed to be anomalously dispersive at the pumping wavelength. To the best of our knowledge, this is the first time a higher-order mode femtosecond pump based broadband SC has been measured from a nonlinear waveguide using the phase-matching method. This enabled us to demonstrate a SC spectrum spanning from 842 to 1462 nm (at - 30 dB), which corresponds to 0.83 octaves, when using the TM10 waveguide mode. When using the TE10 mode, the SC bandwidth is slightly reduced for the same excitation peak power. In addition, we theoretically estimated and discussed the possibility of using the broadband higher-order modes emitted from the Ta2O5 waveguide for trapping nanoparticles. Hence, we believe that demonstrated Ta2O5 waveguide are a promising broadband light source for optical applications such as frequency metrology, Raman spectroscopy, molecular spectroscopy and optical coherence tomography.

Advanced Modulation Format of Probabilistic Shaping Bit Loading for 450-nm GaN Laser Diode based Visible Light Communication.

Visible light communication is an emerging high-speed optical wireless communication technology that can be a candidate to alleviate pressure on conventional radio frequency-based technology. In this paper, for the first time, the advanced modulation format of probabilistic shaping (PS) bit loading is investigated in a high data rate visible light communication system based on a 450-nm Gallium Nitride laser diode. The characteristic of the system is discussed and PS bit loading discrete multi-tone modulation helps to raise the spectral efficiency and improve the system performance. Higher entropy can be achieved in the same signal-to-noise ratio (SNR) and modulation bandwidth limitation, comparing to bit and power loading. With PS bit loading, an available information rate (AIR) of 10.23 Gbps is successfully achieved at the signal bandwidth of 1.5 GHz in a 1.2 m free space transmission with normalized generalized mutual information above 0.92. And higher AIR can be anticipated with an entropy-loading strategy that fixes the channel characteristic. Experimental results validate that a PS bit loading scheme has the potential to increase the system capacity.

Si-QD Synthesis for Visible Light Emission, Color Conversion, and Optical Switching.

This paper reviews the developing progress on the synthesis of the silicon quantum dots (Si-QDs) via the different methods including electrochemical porous Si, Si ion implantation, and plasma enhanced chemical vapor deposition (PECVD), and exploring their featured applications for light emitting diode (LED), color-converted phosphors, and waveguide switching devices. The characteristic parameters of Si-QD LED via different syntheses are summarized for discussion. At first, the photoluminescence spectra of Si-QD and accompanied defects are analyzed to distinguish from each other. Next, the synthesis of porous Si and the performances of porous Si LED reported from different previous works are compared in detail. Later on, the Si-QD implantation in silicide (SiX) dielectric films developed to solve the instability of porous Si and their electroluminescent performances are also summarized for realizing the effect of host matrix to increase the emission quantum efficiency. As the Si-ion implantation still generates numerous defects in host matrix owing to physical bombardment, the PECVD method has emerged as the main-stream methodology for synthesizing Si-QD in SiX semiconductor or dielectric layer. This method effectively suppresses the structural matrix imperfection so as to enhance the external quantum efficiency of the Si-QD LED. With mature synthesis technology, Si-QD has been comprehensively utilized not only for visible light emission but also for color conversion and optical switching applications in future academia and industry.

High-speed integrated micro-LED array for visible light communication.

In this Letter, we report high-speed integrated 14 µm in diameter micro-light-emitting diode (µLED) arrays with the parallel configuration, including ${2} \times {2}$2×2, ${2} \times {3}$2×3, ${2} \times {4}$2×4, and ${2} \times {5}$2×5 arrays. The small junction area of µLED (${\sim}{191}\;\unicode{x00B5}{\rm m}^2$∼191µm2) in each element facilitates the operation of higher injection current density up to ${13}\;{{\rm kA/cm}^2}$13kA/cm2, leading to the highest modulation bandwidth of 615 MHz. The optical power of ${2} \times {5}$2×5 array monotonically increases (${\sim}{10}$∼10 times higher) as the number of arrays increases (1 to 10), while retaining the fast modulation bandwidth. A clear eye diagram up to 1 Gbps without any equalizer further shows the capability of this high-speed transmitter for VLC. These results mean that tailoring the optical power of µLEDs in a parallel-biased integrated array can further enhance the data transmission rate without degradation of the modulation bandwidth.

Long-Lasting Somatic Modifications of Convergent Dendritic Inputs in Hippocampal Neurons.

Integrated neural inputs from different dendrites converge at the soma for action potential generation. However, it is unclear how the convergent dendritic inputs interact at the soma and whether they can be further modified there. We report here an entirely new plasticity rule in hippocampal neurons in which repetitive pairing of subthreshold excitatory inputs from proximal apical and basal dendrites at a precise interval induces persistent bidirectional modifications of the two dendritic inputs. Strikingly, the modification of the dendritic inputs specially occurs at soma in the absence of somatic action potential and requires activation of somatic N-methyl-D-aspartate receptors (NMDARs). Once induced, the somatic modification can also be observed in other unpaired dendritic inputs upon their arrival at the soma. We further reveal that the soma can employ an active mechanism to potentiate the dendritic inputs by promoting sustained activation of somatic NMDARs and subsequent down-regulating of the fast inactivating A-type potassium current (IA) at the soma. Thus, the input-timing-dependent somatic plasticity we uncovered here is in sharp contrast to conventional forms of synaptic plasticity that occur at the dendrites and is important to somatic action potential generation.

Cost-efficient half-duplex 10 Gbit/s all-optical indoor optical wireless communication enabled by a low-cost Fabry-Perot laser/photodetector.

To develop an indoor optical wireless communication (OWC) system, both the system complexity/cost and data rate need to be taken into consideration. In this Letter, a cost-efficient half-duplex OWC system for photonic home area network applications is proposed and experimentally demonstrated. A low-cost Fabry-Perot laser diode is proposed to be employed as both the downlink receiver (Rx) and uplink transmitter at the user side. Enabled by the Fabry-Perot transceiver, the indoor transmission of 10 Gbit/s four-level pulse-amplitude-modulation signal for both downlinks and uplinks is experimentally achieved over a 1.7 km single-mode fiber and 1.1 m free space. Moreover, the proposed scheme also enables us to operate an orthogonal frequency division multiplexing (OFDM) signal. The bit error rate levels of multi-gigabit OFDM data for both downlinks and uplinks over a 10 h measurements are all under a 7% forward error correction limit of 3.8×10-3, which indicates that the proposed system is robust and, thus, can provide a promising solution for high-speed low-cost home area OWC networks.